TC-3218
Public Review Draft
COMMENCEMENT BAY
NEARSHORE/TIDEFLATS
FEASIBILITY STUDY
Volume 1
DECEMBER 1988
PREPARED FOR:
WASHINGTON STATE DEPARTMENT OF ECOLOGY
AND U.S. ENVIRONMENTAL PROTECTION AGENCY
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TC 3218-10
Public Review Draft
COMMENCEMENT BAY NEARSHORE/TIDEFLATS FEASIBILITY STUDY
VOLUME 1
by
Tetra Tech, Inc.
for
Washington Department of Ecology
f and
U.S. Environmental Protection Agency
December 1988
Tetra Tech, Inc.
11820 Northup Way, Suite 100
Bellevue, Washington 98005
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CONTENTS
Paoe
LIST OF FIGURES xii
LIST OF TABLES xvii
1.0 INTRODUCTION 1-1
1.1 BACKGROUND 1-1
1.2 FEASIBILITY STUDY PURPOSE AND APPROACH 1-4
1.3 SITE BACKGROUND 1-6
1.3.1 Study Area Description 1-6
1.3.2 Site History 1-6
1.3.3 Natural Environment 1-8
1.3.4 Nature and Extent of Contamination 1-8
1.3.5 Identification of Problem Chemicals and
Problem Areas 1-11
1.4 FEASIBILITY STUDY REPORT OVERVIEW 1-16
2.0 TECHNICAL AND INSTITUTIONAL BASIS FOR REMEDIATION 2-1
2.1 FEASIBILITY STUDY TECHNICAL FRAMEWORK 2-1
2.1.1 Field Investigations 2-4
2.1.2 Development of Sediment Cleanup Goals 2-4
2.1.3 Response of Sediments to Source Control 2-5
2.1.4 Feasibility of Source Control 2-6
2.1.5 Identify and Screen Sediment Remedial Alternatives 2-6
2.1.6 Identification of Preferred Alternatives 2-8
2.1.7 Integrated Action Plan 2-8
2.2 IDENTIFICATION OF LONG-TERM CLEANUP GOALS 2-9
2.2.1 Background 2-9
2.2.2 Evaluation of Environmental Effects 2-10
2.2.3 Evaluation of Human Health Effects 2-32
2.2.4 Administrative Definition of the Long-term Goal 2-49
2.2.5 Review/Use of New Information 2-54
11
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2.3 USE OF THE LONG-TERM SEDIMENT CLEANUP GOAL 2-55
2.3.1 Defining the Extent of Areas of Concern 2-55
2.3.2 Defining Source Control Needs 2-56
2.3.3 Prioritizing Areas for Remedial Action 2-57
2.3.4 Identifying Sediments Requiring Remediation 2-57
2.3.5 Definition of a Reasonable Sediment Recovery Time 2-58
2.3.6 Sediment Volume Refinement Process 2-58
2.4 RELATIONSHIP BETWEEN THE FEASIBILITY STUDY AND EXISTING
REGULATORY PROGRAMS 2-65
2.4.1 Relationship Between the PSDDA Program and the
Commencement Bay Superfund Project 2-65
2.4.2 Relationship Between the PSWQA Management Plan
Elements and the Commencement Bay Superfund Project 2-68
2.4.3 Relationship Between PSEP and the Commencement Bay
Superfund Project 2-71
2.5 ROUTINE DREDGING WITHIN COMMENCEMENT BAY 2-72
2.5.1 Regulatory Requirements for Routine Dredging
Projects in Puget Sound 2-73
2.5.2 Regulatory Requirements for Routine Dredging
Projects in the High Priority Areas of
Commencement Bay 2-76
2.5.3 Relationship Between Routine Dredging and Sediment
Cleanup Actions 2-76
2.5.4 Conclusions 2-77
3.0 REMEDIAL TECHNOLOGIES FOR DEVELOPMENT OF AREA-WIDE SEDIMENT
REMEDIAL ALTERNATIVES 3-1
3.1 GENERAL RESPONSE ACTIONS FOR SEDIMENTS 3-2
3.1.1 No Action 3-2
3.1.2 Institutional Controls 3-4
3.1.3 In Situ Containment 3-4
3.1.4 Removal 3-4
3.1.5 Treatment 3-8
3.1.6 Disposal Options 3-19
3.1.7 Summary of Preliminary Screening of Sediment
Remedial Technologies 3-31
3,2 SOURCE CONTROLS 3-31
3.2.1 Groundwater 3-33
3.2.2 Surface Water 3.39
3.2.3 Soil 3.45
3.2.4 Air 3-48
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3.3 DEVELOPMENT OF SEDIMENT REMEDIAL ALTERNATIVES 3-50
3.3.1 No Action 3-51
3.3.2 Institutional Controls 3-51
3.3.3 Containment 3-52
3.3.4 Removal 3-52
3.3.5 Treatment 3-52
3.3.6 Disposal 3-55
3.4 IDENTIFICATION OF CANDIDATE REMEDIAL ALTERNATIVES 3-55
3.4.1 No Action 3-56
3.4.2 Institutional Controls 3-57
3.4.3 In Situ Capping 3-57
3.4.4 Removal/Confined Aquatic Disposal 3-58
3.4.5 Removal/Nearshore Disposal 3-59
3.4.6 Removal/Upland Disposal 3-61
3.4.7 Removal/Solidification/Upland Disposal 3-62
3.4.8 Removal/Incineration/Upland Disposal 3-63
3.4.9 Removal/Solvent Extraction/Upland Disposal 3-63
3.4.10 Removal/Land Treatment 3-64
4.0 DEVELOPMENT OF SEDIMENT REMEDIAL ACTION EVALUATION CRITERIA 4-1
4.1 EFFECTIVENESS CRITERIA 4-2
4.1.1 Short-Term Protectiveness 4-2
4.1.2 Timeliness 4-2
4.1.3 Long-Term Protectiveness 4-3
4.1.4 Reduction in Toxicity, Mobility, or Volume 4-4
4.2 IMPLEMENTABILITY CRITERIA 4-4
4.2.1 Technical Feasibility 4-4
4.2.2 Institutional Feasibility 4-5
4.2.3 Availability 4-22
4.3 COST CRITERIA 4-26
4.4 IDENTIFICATION OF PREFERRED ALTERNATIVES 4-27
4.4.1 Short-Term Protectiveness 4-28
4.4.2 Timeliness 4-29
4.4.3 Long-Term Protectiveness 4-29
4.4.4 Reduction in Contaminant Toxicity,
Mobility, or Volume 4-30
4.4.5 Technical Feasibility 4-30
4.4.6 Institutional Feasibility 4-31
4.4.7 Availability 4-31
4.4.8 Cost 4-32
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5.0 HEAD OF HYLEBOS WATERWAY , 5-1
5.1 WATERWAY DESCRIPTION 5-1
5.1.1 Nature and Extent of Contamination 5-2
5.1.2 Recent and Planned Dredging Projects 5-8
5.2 POTENTIAL SOURCES OF CONTAMINATION 5-8
5.2.1 Kaiser Aluminum 5-12
5.2.2 U.S. Gypsum 5-15
5.2.3 B&L Landfill 5-16
5.2.4 Pennwalt 5-17
5.2.5 General Metals, Inc. 5-22
5.2.6 Log Sorting Yards 5-23
5.2.7 Tacoma Boatbuilding Company 5-25
5.2.8 Storm Drains 5-26
5.2.9 Loading Summary 5-29
5.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 5-31
5.3.1 Feasibility of Source Control 5-31
5.3.2 Evaluation of the Potential Success of Source
Control 5-34
5.3.3 Source Control Summary 5-38
5.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 5-39
5.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 5-39
5.5.1 Assembly of Alternatives for Analysis 5-39
5.5.2 Evaluation of Candidate Alternatives 5-41
5.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 5-49
5.7 CONCLUSIONS 5-52
6.0 MOUTH OF HYLEBOS WATERWAY 6-1
6.1 WATERWAY DESCRIPTION 6-1
6.1.1 Nature and Extent of Contamination 6-3
6.1.2 Recent and Planned Dredging Projects 6-4
6.2 POTENTIAL SOURCES OF CONTAMINATION 6-7
6.2.1 Occidental Chemical Corporation 6-10
6.2.2 Loading Summary 6-13
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6.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 6-13
6.3.1 Feasibility of Source Control 6-14
6.3.2 Evaluation of the Potential Success of Source
Control 6-15
6.3.3 Source Control Summary 6-17
6.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 6-19
6.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 6-20
6.5.1 Assembly of Alternatives for Analysis 6-20
6.5.2 Evaluation of Candidate Alternatives 6-21
6.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 6-29
6.7 CONCLUSIONS 6-32
7.0 SITCUM WATERWAY 7-1
7.1 WATERWAY DESCRIPTION 7-1
7.1.1 Nature and Extent of Contamination 7-1
7.1.2 Recent and Planned Dredging Projects 7-3
7.2 POTENTIAL SOURCES OF CONTAMINATION 7-6
7.2.1 Port of Tacoma Terminal 7 Ore Unloading Facilities 7-8
7.2.2 Storm Drains 7-9
7.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 7-13
7.3.1 Feasibility of Source Control 7-14
7.3.2 Evaluation of the Potential Success of Source
Control 7-15
7.3.3 Source Control Summary 7-17
7.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 7-19
7.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 7-20
7.5.1 Assembly of Alternatives for Analysis 7-20
7.5.2 Evaluation of Candidate Alternatives 7-21
7.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 7-29
7.7 CONCLUSIONS 7-32
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8.0 ST. PAUL WATERWAY 8-1
8.1 WATERWAY DESCRIPTION 8-1
8.1.1 Nature and Extent of Contamination 8-3
8.1.2 Recent and Planned Dredging Projects 8-3
8.2 POTENTIAL SOURCES OF CONTAMINATION 8-6
8.2.1 Simpson Tacoma Kraft Pulp Mill 8-6
8.2.2 Storm Drains 8-11
8.2.3 Loading Summary 8-14
8.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 8-14
8.3.1 Feasibility of Source Control 8-15
8.3.2 Evaluation of the Potential Success of Source
Control 8-16
8.3.3 Source Control Summary 8-19
8.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 8-19
8.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 8-19
8.5.1 Assembly of Alternatives for Analysis 8-19
8.5.2 Evaluation of Candidate Alternatives 8-21
8.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 8-29
8.7 CONCLUSIONS 8-30
9.0 MIDDLE WATERWAY 9-1
9.1 WATERWAY DESCRIPTION 9-1
9.1.1 Nature and Extent of Contamination 9-1
9.1.2 Recent and Planned Dredging Projects 9-3
9.2 POTENTIAL SOURCES OF CONTAMINATION 9-6
9.2.1 Ship Repair Facilities 9-6
9.2.2 Storm Drains 9-9
9.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 9-11
9.3.1 Feasibility of Source Control 9-11
9.3.2 Evaluation of the Potential Success
of Source Control 9-13
9.3.3 Source Control Summary 9-16
9.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 9-16
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9.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 9-17
9.5.1 Assembly of Alternatives for Analysis 9-17
9.5.2 Evaluation of Candidate Alternatives 9-18
9.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 9-26
9.7 CONCLUSIONS 9-29
10.0 HEAD OF CITY WATERWAY 10-1
10.1 WATERWAY DESCRIPTION 10-1
10.1.1 Nature and Extent of Contamination 10-1
10.1.2 Recent and Planned Dredging Projects 10-5
10.2 POTENTIAL SOURCES OF CONTAMINATION 10-9
10.2.1 Storm Drains 10-11
10.2.2 Martinac Shipbuilding 10-20
10.2.3 Groundwater 10-21
10.2.4 American Plating 10-22
10.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 10-22
10.3.1 Feasibility of Source Control 10-23
10.3.2 Evaluation of the Potential Success of Source
Control 10-26
10.3.3 Source Control Summary 10-29
10.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 10-31
10.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 10-31
10.5.1 Assembly of Alternatives for Analysis 10-31
10.5.2 Evaluation of Alternatives 10-32
10.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 10-40
10.7 CONCLUSIONS 10-42
11.0 WHEELER-OSGOOD WATERWAY 11-1
11.1 WATERWAY DESCRIPTION 11-1
11.1.1 Nature and Extent of Contamination 11-1
11.1.2 Recent and Planned Dredging Projects 11-4
11.2 POTENTIAL SOURCES OF CONTAMINATION 11-4
vm
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11.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 11-10
11.3.1 Feasibility of Source Control 11-10
11.3.2 Evaluation of the Potential Success of Source
Control I*'11
11.3.3 Source Control Summary 11-13
11.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 11-15
11.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 11-15
11.5.1 Assembly of Alternatives for Analysis 11-15
11.5.2 Evaluation of Alternatives 11-16
11.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 11-25
11.7 CONCLUSIONS 11-26
12.0 MOUTH OF CITY WATERWAY 12-1
12.1 WATERWAY DESCRIPTION 12-1
12.1.1 Nature and Extent of Contamination 12-1
12.1.2 Recent and Planned Dredging Projects 12-3
12.2 POTENTIAL SOURCES OF CONTAMINATION 12-3
12.2.1 D Street Petroleum Storage Facilities 12-7
12.2.2 Storm Drains 12-10
12.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 12-10
12.3.1 Feasibility of Source Control 12-10
12.3.2 Evaluation of the Potential Success of Source
Control 12-11
12.3.3 Source Control Summary 12-14
12.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 12-14
12.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 12-15
12.5.1 Assembly of Alternatives for Analysis 12-15
12.5.2 Evaluation of Alternatives 12-16
12.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 12-20
12.7 CONCLUSIONS 12-21
IX
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13.0 RUSTON-PT. DEFIANCE SHORELINE 13-1
13.1 WATERWAY DESCRIPTION 13-1
13.1.1 Nature and Extent of Contamination 13-3
13.1.2 Recent and Planned Dredging Projects 13-7
13.2 POTENTIAL SOURCES OF CONTAMINATION 13-7
13.2.1 American Smelting and Refining Company 13-7
13.2.2 Loading Summary 13-14
13.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION 13-15
13.3.1 Feasibility of Source Control 13-15
13.3.2 Evaluation of the Potential Success of Source
Control 13-16
13.3.3 Source Control Summary 13-20
13.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION 13-21
13.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES 13-22
13.5.1 Assembly of Alternatives for Analysis 13-22
13.5.2 Evaluation of Alternatives 13-24
13.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE 13-32
13.7 CONCLUSIONS 13-34
14.0 SUMMARY OF PREFERRED ALTERNATIVES 14-1
14.1 PREFERRED ALTERNATIVES 14-1
14.1.1 Removal/Confined Aquatic Disposal 14-1
14.1.2 Removal/Nearshore Disposal 14-3
14.1.3 In Situ Capping 14-3
14.1.4 Institutional Controls 14-4
14.2 COST ANALYSIS 14-4
14.3 NATURAL SEDIMENT RECOVERY 14-11
14.4 HABITAT RESTORATION 14-11
14.4.1 Benthic Habitat in Problem Areas 14-14
14.4.2 Intertidal Habitat in Problem Areas 14-14
14.4.3 Benthic Habitat in Confined Aquatic Disposal Areas 14-14
14.4.4 Intertidal Habitat in Nearshore Disposal Areas 14-14
14.4.5 Habitats at or adjacent to Upland Disposal Sites 14-14
15.0 REFERENCES 15-1
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VOLUME 2 - APPENDICES
APPENDIX A. EVALUATION OF SEDIMENT RECOVERY
APPENDIX B. DETAILS OF DREDGING AND CAPPING TECHNOLOGIES
APPENDIX C. SPECIFICATIONS OF MAJOR ARARs AND TBCs
APPENDIX D. METHOD FOR ESTIMATING COSTS OF SEDIMENT REMEDIAL
ALTERNATIVES
APPENDIX E. SOURCE LOADING DATA
APPENDIX F. SAMPLING STATION LOCATIONS
APPENDIX G. FIELD SURVEY DATA REPORT - MAY 1986
xi
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FIGURES
Number Page
1-1 Commencement Bay Nearshore/Tideflats study area 1-7
1-2 Waterway segments defined during the remedial investigation
for the Commencement Bay study area 1-12
1-3 Relationship between problem areas identified during the
remedial investigation and those studied for the feasibility
study 1-17
2-1 Relationships among programs to identify and correct
sediment contamination problems in the Commencement Bay
N/T site 2-2
2-2 Measures of reliability (sensitivity and efficiency) 2-17
2-3 The AET approach to sediments tested for lead and
4-methylphenol concentrations and amphipod mortality
during bioassays 2-19
2-4 Hypothetical example of dose-resonse relationship
resulting from laboratory exposure to single chemicals
X and Y 2-22
2-5 Hypothetical example of toxic response resulting from
exposure to environmental samples of sediment contami-
nated with chemicals X and Y 2-23
2-6 Hypothetical example of AET calculation for chemical X
based on classification of significant and nonsignificant
responses for environmental samples contaminated with
both chemicals X and Y 2-24
2-7 Hypothetical dose-response relationships for a carcinogen
and a noncarcinogen 2-35
2-8 Graphical risk characterization for PCBs in seafood 2-42
2-9 Refinement of sediment cleanup volume estimates 2-60
2-10 Theoretical relationships among AET, long-term cleanup
goals, and short-term cleanup goals 2-62
3-1 Response action, technology types, and process options
for remediation of contaminated sediments 3-3
xii
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3-2 Confined aquatic disposal of contaminated dredged material 3-20
3-3 Confined nearshore disposal of contaminated dredged
material 3-23
3-4 Confined upland disposal (a) and components of a typical
diked upland disposal site (b) 3-24
3-5 Potential Commencement Bay disposal sites identified by
Phillips et al. (1985) 3-27
3-6 Potential sediment remedial technologies and process options
that are retained for further evaluation 3-32
3-7 Comparative pollutant removal of urban best management
practice (BMP) designs, as determined by Schueler (1987) 3-41
3-8 Dredge water chemical clarification facility 3-54
5-1 Head of Hylebos Waterway - existing industries and
businesses 5-3
5-2 Areal and depth distributions of arsenic in sediments at
the head of Hylebos Waterway, normalized to long-term
cleanup goal 5-5
5-3 Areal and depth distributions of HPAH in sediments at the
head of Hylebos Waterway, normalized to long-term cleanup
goal 5-6
5-4 Areal and depth distributions of PCBs in sediments at the
head of Hylebos Waterway, normalized to long-term cleanup
goal 5-7
5-5 NPDES-permitted and nonpermitted discharges to Hylebos
Waterway 5-11
5-6 Surface water drainage pathways to the head of Hylebos
Waterway 5-13
5-7 Drainage basin for Morningside Ditch 5-28
5-8 Sediments at the head of Hylebos Waterway not meeting
cleanup goals for indicator chemicals at present and 10 yr
after implementing feasible source control 5-37
6-1 Mouth of Hylebos Waterway - existing industries and
businesses 6-2
xm
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6-2 Area! and depth distributions of PCBs in sediments at the
mouth of Hylebos Waterway, normalized to long-term cleanup
goal 6~5
6-3 Areal and depth distributions of hexachlorobenzene in
sediments at the mouth of Hylebos Waterway, normalized to
long-term cleanup goal 6-6
6-4 NPDES-permitted and nonpermitted discharges to Hylebos
Waterway 6-8
6-5 Sediments at the mouth of Hylebos Waterway not meeting
cleanup goals for indicator chemicals at present and 10 yr
after implementing feasible source control 6-18
7-1 Sitcum Waterway - existing industries, businesses, and
discharges 7-2
7-2 Areal and depth distributions of copper in sediments of
Sitcum Waterway, normalized to long-term cleanup goal 7-4
7-3 Areal and depth distributions of arsenic in sediments of
Sitcum Waterway, normalized to long-term cleanup goal 7-5
7-4 Surface water drainage pathways to Sitcum Waterway 7-10
7-5 Sediments in Sitcum Waterway not meeting cleanup
goals at present and 10 yr after implementing feasible
source control 7-18
8-1 St. Paul Waterway - existing industries, businesses, and
discharges 8-2
8-2 Areal and depth distributions of 4-methylphenol in sediments
of St. Paul Waterway, normalized to long-term cleanup goal 8-4
8-3 Remedial actions at the Simpson Tacoma Kraft Company
facility 8-5
8-4 Proposed stormwater control areas at the Simpson Tacoma
Kraft Company facility 8-12
8-5 Surface water drainage pathways to St. Paul Waterway 8-13
8-6 Sediments in St. Paul Waterway not meeting cleanup goals
for indicator chemicals at present and 10 yr after imple-
menting feasible source control 8-18
9-1 Middle Waterway - existing industries, businesses, and
discharges 9-2
xiv
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9-2 Area! and depth distributions of mercury in sediments
of Middle Waterway, normalized to long-term cleanup goal 9-4
9-3 Areal and depth distributions of copper in sediments of
Middle Waterway, normalized to long-term cleanup goal 9-5
9-4 Surface water drainage pathways to Middle Waterway 9-10
9-5 Sediments in Middle Waterway not meeting cleanup goals
for indicator chemicals at present and 10 yr after imple-
menting feasible source control 9-15
10-1 Head of City Waterway - existing industries and businesses 10-2
10-2 Areal and depth distributions of HPAH in sediments at the
head of City Waterway, normalized to long-term cleanup
goal 10-4
10-3 Areal and depth distributions of cadmium in sediments at
the head of City Waterway, normalized to long-term cleanup
goal 10-6
10-4 Areal and depth distributions of lead in sediments at the
head of City Waterway, normalized to long-term cleanup goal 10-7
10-5 Areal and depth distributions of mercury in sediments at
the head of City Waterway, normalized to long-term cleanup
goal 10-8
10-6 Surface water drainage pathways to the head of City
Waterway 10-12
10-7 Drainage basins for City Waterway 10-13
10-8 Sediments at the head of City Waterway not meeting cleanup
goals for indicator chemicals at present and 10 yr after
implementing feasible source control 10-28
11-1 Wheeler-Osgood Waterway - existing businesses and
industries 11-2
11-2 Areal and depth distributions of HPAH in sediments of
Wheeler-Osgood Waterway, normalized to long-term cleanup
goal 11-3
11-3 Areal and depth distributions of zinc in sediments of
Wheeler-Osgood Waterway, normalized to long-term cleanup
goal 11-5
11-4 Surface water drainage pathways to Wheeler-Osgood Waterway 11-7
xv
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11-5 Sediments in Wheeler-Osgood Waterway not meeting cleanup
goals for indicator chemicals at present and 10 yr after
implementing feasible source control 11-14
12-1 Mouth of City Waterway - existing industries and businesses 12-2
12-2 Areal and depth distributions of HPAH in sediments at the
mouth of City Waterway, normalized to long-term cleanup
goal 12-4
12-3 Areal and depth distributions of mercury in sediments at
the mouth of City Waterway, normalized to long-term cleanup
goal 12-5
12-4 Surface water drainage pathways to the mouth of City
Waterway 12-6
12-5 Sediments at the mouth of City Waterway not meeting cleanup
goals for indicator chemicals at present and 10 yr after
implementing feasible source control 12-13
13-1 Ruston-Pt. Defiance Shoreline - existing industries,
businesses, and discharges 13-2
13-2 Areal and depth distributions of arsenic in sediments of
Ruston-Pt. Defiance Shoreline, normalized to long-term
cleanup goal 13-4
13-3 Areal and depth distributions of mercury in sediments of
Ruston-Pt. Defiance Shoreline, normalized to long-term
cleanup goal 13-5
13-4 Areal and depth distributions of LPAH in sediments of
Ruston-Pt. Defiance Shoreline, normalized to long-term
cleanup goal 13-6
13-5 Sediments along the Ruston-Pt. Defiance Shoreline not
meeting cleanup goals for indicator chemicals at present
and 10 yr after implementing feasible source control 13-19
14-1 Estimated remediation costs related to sediment volume for
preferred alternatives in each problem area 14-10
xvi
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TABLES
Number Page
1-1 Final ranking of problem areas in the Commencement Bay
remedial investigation 1-15
1-2 Revised designations for problem areas in the Commencement
Bay Nearshore/Tideflats site 1-19
2-1 Approaches evaluated for establishing sediment quality
values 2-13
2-2 Potential guideline concentrations for PCBs in fish tissue,
Commencement Bay N/T Feasibility Study 2-43
2-3 Predicted vs. observed PCB concentrations in fish tissue
from Commencement Bay 2-45
2-4 Sediment quality values that are expected to result in
background concentrations of PCBs in fish of Commencement
Bay 2-46
2-5 Average sediment PCB concentrations achieved with alter-
native cleanup levels 2-48
2-6 Cleanup goal options considered for Commencement Bay N/T
Feasibility Study 2-52
2-7 Biological disposal guidelines for alternative site
management conditions 2-75
3-1 Potential sites for contaminated dredged material disposal 3-28
4-1 Selected potential chemical-specific ARARs for problem
area chemicals 4-13
4-2 Selected potential chemical-specific TBCs 4-15
4-3 Selected potential location-specific ARARs for candidate
remedial alternatives 4-17
4-4 Selected potential action-specific ARARs for candidate
remedial alternatives 4-23
5-1 Head of Hylebos Waterway - source status 5-9
xvii
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5-2 Effectiveness of source control for head of Hylebos
Waterway 5~32
5-3 Head of Hylebos Waterway summary of sediment recovery
calculations 5-36
5-4 Remedial alternatives evaluation matrix for the head of
Hylebos Waterway problem area 5-42
5-5 Evaluation summary for head of Hylebos Waterway 5-44
6-1 Mouth of Hylebos Waterway - source status 6-9
6-2 Mouth of Hylebos Waterway summary of sediment recovery
calculations 6-16
6-3 Remedial alternatives evaluation matrix for the mouth of
Hylebos Waterway problem area 6-22
6-4 Evaluation summary for mouth of Hylebos Waterway 6-24
7-1 Sitcum Waterway - source status 7-7
7-2 Storm drains discharging into Sitcum Waterway 7-11
7-3 Sitcum Waterway summary of sediment recovery calculations 7-16
7-4 Remedial alternatives evaluation matrix for the Sitcum
Waterway problem area 7-22
7-5 Evaluation summary for Sitcum Waterway 7-24
8-1 St. Paul Waterway - source status 8-7
8-2 St. Paul Waterway summary of sediment recovery calculations 8-17
8-3 Remedial alternatives evaluation matrix for the St. Paul
Waterway problem area 8-22
8-4 Evaluation summary for St. Paul Waterway 8-24
9-1 Middle Waterway - source status 9-7
9-2 Middle Waterway summary of sediment recovery calculations 9-14
9-3 Remedial alternatives evaluation matrix for the Middle
Waterway problem area 9-19
9-4 Evaluation summary for Middle Waterway 9-21
10-1 Head of City Waterway - source status 10-10
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10-2 Commercial discharges to storm drains CN-237 and CS-237
identified during sewer utility business inspections 10-15
10-3 Commercial discharges to storm drain CI-230 identified
during sewer utility business inspections 10-18
10-4 Effectiveness of source control for head of City Waterway 10-24
10-5 Head of City Waterway summary of sediment recovery
calculations 10-27
10-6 Average percent reductions needed to achieve long-term
cleanup goal concentrations of indicator chemicals in
storm drain effluent particulate matter or sediments 10-30
10-7 Remedial alternatives evaluation matrix for the head of
City Waterway problem area 10-33
10-8 Evaluation summary for the head of City Waterway 10-35
11-1 Wheeler-Osgood Waterway - source status 11-6
11-2 Storm drains discharging into Wheeler-Osgood Waterway 11-9
11-3 Wheeler-Osgood Waterway summary of sediment recovery
calculations 11-12
11-4 Remedial alternatives evaluation matrix for the Wheeler-
Osgood Waterway problem area 11-17
11-5 Evaluation summary for Wheeler-Osgood Waterway 11-20
12-1 Mouth of City Waterway - source status 12-8
12-2 Mouth of City Waterway summary of sediment recovery
calculations 12-12
12-3 Remedial alternatives evaluation matrix for the mouth of
City Waterway problem area 12-17
12-4 Evaluation summary for mouth of City Waterway 12-19
13-1 Ruston-Pt. Defiance shoreline - source status 13-8
13-2 Ruston-Pt. Defiance shoreline summary of sediment recovery
calculations 13-18
13-3 Remedial alternatives evaluation matrix for the Ruston-
Pt. Defiance shoreline problem area 13-25
13-4 Evaluation summary for Ruston-Pt. Defiance shoreline 13-27
xix
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14-1 Alternatives evaluated for each problem area 14-2
14-2 Summary of remedial sediment surface areas and volumes 14-5
14-3 Cost summary for preferred alternatives 14-6
14-4 Sediment cleanup summary for Commencement Bay 14-7
14-5 Factors affecting cost estimates 14-8
14-6 Sediment recovery factors 14-12
14-7 Maximum enrichment ratios that are predicted to recover
to acceptable levels in a given time period 14-13
14-8 Estimated intertidal surface areas and volumes to be
disturbed by sediment remedial action 14-15
xx
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1.0 INTRODUCTION
This report documents the feasibility study (FS) prepared for the
waterways/shoreline portion of the Commencement Bay Nearshore/Tideflats
(N/T) Superfund site in Tacoma, Washington. The purpose of the FS was to
develop and evaluate the most appropriate remedial strategies for correcting
the human health and environmental impacts associated with contaminated
sediments in the Commencement Bay N/T site.
1.1 BACKGROUND
The feasibility study represents the end of the Superfund investigation
and evaluation phase. This phase began in October 1981, when Commencement
Bay was listed as the highest priority site for action in the State of
Washington on an interim priority list developed by the U.S. Environmental
Protection Agency (EPA) under the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA). The Commencement Bay site
was initially divided into four areas: deepwater, nearshore, tideflats
industrial, and the South Tacoma Channel. On a subsequent priority list
published on 30 December 1982, the nearshore and tideflats industrial areas
of Commencement Bay were designated as a discrete Superfund site, as was the
South Tacoma Channel. The deepwater area was eliminated as a priority site
because water quality studies indicated less severe contamination in that
area than was initially suspected. On 6 September 1983, the U.S. EPA
published and promulgated the first official National Priorities List (NPL)
of hazardous waste sites. This list included the Commencement Bay N/T site.
Earlier that year, on 13 April 1983, the U.S. EPA announced that an
agreement had been reached with the Washington Department of Ecology
(Ecology) to conduct a remedial investigation/feasibility study (RI/FS) of
the hazardous substance contamination in the N/T site. The RI/FS comprises
two distinct parts: metals contamination of the upland environment near the
American Smelting and Refining Company (ASARCO) smelter (the Ruston/Vashon
task), and chemical contamination and its effects in the marine environment
(waterways/shoreline tasks). This report addresses only the waterways/shore-
line tasks. References herein to Commencement Bay problem areas and reports
are also limited to the waterways/shoreline tasks of the Commencement Bay
Nearshore/Tideflats RI/FS.
Under the Superfund remedial program, long-term remedial response
actions are undertaken to stop or substantially reduce actual or threatened
releases of hazardous substances that are serious, but not immediately
life-threatening. A remedial response has two main phases: an RI/FS, and a
remedial design/remedial action (RD/RA) phase. During the RI/FS, conditions
at the site are studied, problems are characterized, and alternative methods
to clean up the site are evaluated. In the RD/RA phase, the recommended
cleanup strategy is refined via further sampling and testing, an approach is
designed and engineered, and final construction and cleanup are undertaken.
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Ecology was designated as the lead agency for the RI/FS. Ecology
contracted with Tetra Tech, Inc. to perform the RI and the FS. The RI phase
was initiated in 1983, and the final results were published in August 1985
(Tetra Tech 1985a,b). Results presented in the RI included identification
of nine high priority problem areas in the Commencement Bay N/T site,
identification of problem chemicals within the nine problem areas, and
identification of potential sources of the problem chemicals.
Following the completion of the RI, two approaches were developed to
address sediment contamination problems in Commencement Bay. First, Ecology
and EPA expanded ongoing source control efforts in the Commencement Bay
area. These expanded efforts focused on controlling or eliminating the
ongoing release of chemicals into the high priority problem areas. The
source control effort involved a number of programs, and individual actions
have been taken using the most appropriate program mechanism [e.g., enforce-
ment under the Clean Water Act (CWA), and the Resource Conservation and
Recovery Act (RCRA)]. Examples of source control actions undertaken in
Commencement Bay include the investigation and control of surface water
runoff from several log sorting yards in the area.
The second major effort that was initiated following the completion of
the RI was the FS. This effort includes the identification, evaluation, and
recommendation of corrective measures for each of the nine high priority
problem areas. The preferred alternatives recommended for each problem area
integrate source control and sediment remedial'actions, and include natural
recovery of sediments (i.e., degradation or burial of contaminated surface
sediments beneath clean material) as a component of the remedial alternative.
An Integrated Action Plan (IAP) was developed to integrate feasible
source controls and the results of the FS to correct sediment contamination
problems in Commencement Bay. The plan presents the required actions,
prioritizes those actions, and provides a schedule for their implementation
(PTI 1988a).
The purpose of this FS, led by Ecology under a cooperative agreement
with U.S. EPA, is to develop and evaluate the most appropriate remedial
strategies for correcting the documented biological and human health impacts
associated with contaminated sediments at'the Commencement Bay N/T site.
Completion and publication of this FS report is an important milestone in
the long-term response action being conducted at the site, because it
represents a transition from a study phase to an active cleanup phase.
This transition is highlighted by and dependent on one of the most
important opportunities for public participation in the Superfund process:
the public comment period. During the public comment period, the FS is made
available for review, and comments on cleanup alternatives, including the
agencies' proposed plan, are actively solicited. Following the public
comment period, the agencies will prepare a responsiveness summary describing
and responding to significant community comments on the proposed remedial
action and the other alternatives considered. Finally, based on both the
information developed in the FS and on the public comments discussed in the
responsiveness summary, the agencies will select a remedial action plan.
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This plan will be described in a Record of Decision (ROD) document. The
Commencement Bay ROD will be performance-based as a result of detailed site
investigations and area by area evaluations of remedial alternatives. A
performance-based ROD is more flexible than the usual technology-based ROD
that assumes certain remedial technologies will be used under a given set of
environmental circumstances. The flexibility of the performance-based ROD
is due to the potential to vary from the recommended alternative if future
technologies contribute to new alternatives that become preferred over
presently recommended alternatives. The ROD will be the blueprint for
continuation of the long-term remedial response action at the Commencement
Bay N/T site under the Superfund remedial program. Post-ROD activities will
be implemented according to the IAP (PTI 1988a) (Section 2.1.6).
The FS was conducted in accordance with CERCLA, as amended by the
Superfund Amendments and Reauthorization Act (SARA) of 1986. However, given
the large study area, the multiplicity of contaminant sources, and the
diversity of ongoing activities within the Commencement Bay N/T site, the
development of the FS and the plans for implementing the recommended
remedial strategies differ in many respects from the reports and implemen-
tation strategies at more traditional Superfund sites. Of particular
importance are the following distinctions:
• Correction of sediment contamination problems will be
accomplished through the implementation of these measures:
1) Source control measures to reduce or eliminate ongoing
releases of hazardous substances
2) Natural recovery through chemical degradation, deposition
of clean sediments, and diffusive loss to overlying
water
3) Institutional controls such as public warnings to reduce
potential human exposure
4) Routine dredging, which will result in the removal of
contaminated sediments and their subsequent disposal at
appropriate facilities (i.e., those designed for
sediments with a given level of contamination)
5) Sediment remedial actions (e.g., removal, capping,
treatment) for highly contaminated sediments.
• Correction of sediment contamination problems will be
implemented over a period of several years. In the short
term, regulatory efforts will focus on measures to reduce or
eliminate the ongoing release of contaminants. These
measures, in conjunction with natural processes such as
biodegradation and sedimentation, will reduce exposure to
contaminated sediments. During this initial timeframe, it
1-3
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is anticipated that routine dredging projects will continue
to occur. Regulatory requirements for dredging in high
priority areas are presented in Section 2.5.2. These
activities will have the net effect of removing some
contaminated sediments from the waterways. After source
control measures are implemented and monitoring is performed
to verify the effectiveness of such controls and natural
sediment recovery, actions to remediate areas of high
sediment contamination will be initiated. This remediation
will proceed in two phases: 1) detailed sediment sampling to
refine the estimates of areal extent of individual problem
areas and 2) implementation of the appropriate remedial
measures.
• Correction of sediment contamination problems will be
implemented by several agencies using a wide variety of
existing regulatory authorities. Wastewater discharges will
continue to be regulated under state and federal water
quality laws. Stormwater and industrial pretreatment
requirements will be implemented under federal, state, and
local laws and regulations. The Commencement Bay Action Team
will continue to oversee implementation of source control.
Routine dredging projects will continue to be regulated under
the federal Clean Water Act Section 404 program. Remediation
of highly contaminated sediments will be required under state
and federal Superfund laws.
• Correction of sediment contamination problems will be
implemented using a performance-based cleanup plan (perfor-
mance-based Record of Decision). Each completed cleanup will
be required to satisfy performance criteria (i.e., specific
cleanup levels). A performance-based cleanup provides
flexibility in selecting cleanup options because the specific
techniques to be used for each area will be defined during
the detailed engineering design phase. This approach
provides the flexibility to use the most appropriate
techniques available at the time cleanup occurs. Since
sediment cleanup (i.e., source control and sediment remedial
actions) may span 5 to 15 yr, new, and possibly more
effective, techniques may be available in the future.
Consequently, the preferred alternative 10 yr from now may
differ substantially from those identified in this report.
1.2 FEASIBILITY STUDY PURPOSE AND APPROACH
The purpose of the FS was to develop and evaluate the most appropriate
remedial strategies for correcting short- and long-term hazards associated
with contaminated sediments in the Commencement Bay N/T site. The remedi-
ation strategies, which were developed to protect human health and the
environment, are based upon an analysis of the actual and potential hazards
at the site. Each remedial strategy addresses source control/natural
sediment recovery, institutional controls, routine dredging, and sediment
1-4
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cleanup. This comprehensive approach is designed to ensure that long-term
solutions to the existing sediment problems are implemented in a timely and
cost-effective manner.
The feasibility of institutional controls and sediment cleanup actions
were evaluated using the standard Superfund evaluation approach. The
objective of this evaluation was to determine cleanup activities necessary
to meet the long-term goal (LTG) of sediments causing no adverse biological
impacts. Areas and volumes of contaminated sediments were estimated based
upon an analysis of sediment chemistry and observed biological effects, and
upon the predicted results of source controls and natural recovery processes.
Alternatives were developed and analyzed in accordance with the most recent
U.S. EPA (1988) guidance. The evaluation process involved consideration of
the effectiveness, implementability, and costs of various remedial alter-
natives.
The FS report does not contain a detailed engineering and cost
evaluation for individual source control measures. Many of the source
control actions identified herein are currently being implemented by local
industries in response to enhanced Ecology and U.S. EPA regulatory efforts
during the last several years. This enhanced effort began in the fall of
1985, when Ecology created the Commencement Bay Action Team. This Action
Team, based in Ecology's Southwest Regional Office, has utilized a multi-
programmatic approach to controlling sources. The four members of this
team have utilized permitting mechanisms, enforcement orders, consent orders
and decrees, or court action to control sources of toxic contaminants. Many
of the sites being handled by the Action Team were identified as high
priority sites in the RI (Tetra Tech 1985a,b). Regulatory actions have
resulted in the collection of additional data that have been incorporated
into the FS evaluations. Upon completion of the FS, source control actions
will continue to be handled under these existing regulatory programs.
The FS report provides an overall framework for performing detailed
evaluation of source control actions. Existing sediment contamination data
and current knowledge of source inputs were used to determine the levels of
source control required to maintain long-term sediment quality at acceptable
levels. These source control requirements were compared to the estimated
levels of source control achievable through the use of all known, available,
and reasonable technologies. The source control evaluation consists of the
following components:
• Identifying major sources
• Estimating source loadings
• . Examining the relationships between sources and sediment
contamination
• Estimating the degree of source control needed to allow
natural recovery of sediment contamination problems
• Identifying available control technologies
1-5
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• Estimating the degree of source control obtainable through
the implementation of all known, available, and reasonable
methods of treatment
• Recommending source control investigations and actions to
correct ongoing problems.
The preferred alternative for each problem area addresses both source
control and sediment remedial measures. The overall framework for implemen-
ting the preferred alternative is described in a separate document, the
"Commencement Bay Nearshore/Tideflats Integrated Action Plan" (PTI 1988a).
1.3 SITE BACKGROUND
1.3.1 Study Area Description
Commencement Bay covers approximately 9 mi2 in southern Puget Sound,
Washington (Figure 1-1). The bay opens to Puget Sound in the northwest,
with the City of Tacoma situated on the south and southeast shore. A number
of waterways and the Puyallup River adjoin Commencement Bay. The drainage
area for the Puyallup River is approximately 950 mi2.
The N/T Superfund site includes 10-12 mi2 of shallow water, shoreline,
and adjacent land. The Commencement Bay Nearshore is defined as the area
along the Ruston shoreline from the head of City Waterway to Pt. Defiance.
It includes all water with depths of less than 60 ft below mean lower low
water (MLLW). The maximum depth of the study area along the Ruston-
Pt. Defiance shoreline was increased to 200 ft when sediments with contami-
nant concentrations that exceeded cleanup goals were found at depths greater
than 200 ft. The 200 ft depth contour was selected because some dredging
techniques are capable of dredging to that depth. The Tideflats area
includes Hylebos, Blair, Sitcum, Milwaukee, St. Paul, Middle, Wheeler-Osgood,
and City Waterways; the Puyallup River upstream to the Interstate-5 bridge;
and the adjacent land areas. The landward boundary of the Tideflats is
defined by drainage pathways rather than political boundaries.
The land, water, and shorelines within the study area are owned by
various parties, including the State of Washington, the Port of Tacoma, the
City of Tacoma, Pierce County, the Puyallup Tribe of Indians, and numerous
private entities. Much of the publicly owned land is leased to private and
industrial enterprises. The names and locations of many of these enterprises
are presented in Chapters 5-13 of this report.
1.3.2 Site History
At the time of urban and industrial development in the late 1800s, the
south end of Commencement Bay was composed largely of tideflats formed by the
Puyallup River delta. Dredge and fill activities have significantly altered
the estuarine nature of the bay since the 1920s. Intertidal areas were
covered, and meandering streams and rivers were channelized. Numerous
industrial and commercial operations have located in the filled areas of the
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HJSTON-PONT
DEFIANCE SHORELINE
'*, Commencement
•
MOUTH OF HYLEBOS
WATERWAY
11111111 Commencement Bay
Nearshore/Tideflats
Study Area
Problem Areas Evaluated
lor Sediment Remediation
in the Feasibility Study
TACOMA
) mies WHEELER-OSQOOD
I kilometers WATERWAY ST. PAUL
2 WATERWAY
MOUTHOFCrTY
WATERWAY
HEADOFHYLEBOS
WATERWAY
Figure 1-1. Commencement Bay Nearshore/Tideflats study area.
1-7
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bay for purposes of shipbuilding, chemical production, ore smelting, oil
refining, food preserving, transportation, and other urban activities.
Since initial industrialization of the Commencement Bay area, hazardous
substances and waste materials have been released into the environment. As
a result of these various uses and releases of waste materials, the chemical
quality of the waters and sediments in many areas of Commencement Bay has
been altered. Contaminants found in the area include arsenic, lead, zinc,
cadmium, copper, mercury, and a variety of organic compounds [e.g.,
polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAH)].
Contaminants in the Commencement Bay area originate from both point and
nonpoint sources. Industrial surveys conducted by the Tacoma-Pierce County
Health Department and the Port of Tacoma indicate that there are more than
281 industrial activities in the Commencement Bay N/T area. Approximately
34 of these are National Pollutant Discharge Elimination System (NPDES)-
permitted dischargers, including two sewage treatment plants. Nonpoint
sources include two creeks; the Puyallup River; numerous storm drains,
seeps, and open channels; groundwater seepage; atmospheric deposition; and
spills. The Tacoma-Pierce County Health Department has identified approxi-
mately 480 point and nonpoint sources that empty into the Commencement Bay
N/T area (Rogers et al. 1983).
1.3.3 Natural Environment
Commencement Bay., like much of Puget Sound, supports important fishery
resources. Four salmonid species (i.e., chinook, coho, chum, and pink) and
steel head occupy Commencement Bay for part of their life cycle. These
anadromous species have critical estuarine migratory and rearing habitat
requirements. Adults pass through the bay enroute to their spawning
grounds, and juveniles reside in nearshore estuarine areas. Recreational and
commercial harvesting of these species occur in the bay. The Commencement
Bay area also supports extensive inshore marine fish resources. Flatfish,
including English sole, rock sole, flathead sole, c-o sole, sand sole,
starry flounder, and speckled sanddab, are most abundant within the
waterways. Rock sole, c-o sole, and several species of rockfish are most
abundant along the outer shoreline. Although there is an advisory against
the consumption of fish, shellfish, and crabs caught within the study area,
recreational harvesting of many of these species occurs primarily within
City Waterway and along the Ruston-Pt. Defiance shoreline.
1.3.4 Nature and Extent of Contamination
There is considerable variability in the types and concentrations of
chemical contaminants in Commencement Bay sediments. The primary objective
of the RI was to define the nature and extent of sediment contamination.
That investigation involved the compilation and evaluation of existing data
and an extensive field sampling effort to collect additional data. The
distribution of sediment contaminants is presented in the RI report (Tetra
Tech 1985a). The RI findings are summarized below and incorporated into
Chapters 5-13.
1-8
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Sediment Contamination--
Investigations of the nearshore waters of Commencement Bay have
demonstrated the existence of sediment contamination by toxic pollutants,
accumulation of some of these substances by biota, and possible pollution-
associated abnormalities in indigenous biota (Crecelius et al. 1975; Riley
et al. 1980, 1981; Mai ins et al. 1980, 1982; Gahler et al. 1982; Tetra Tech
1985a, 1988; Parametrix 1987). The highest concentrations of certain metals
(i.e., arsenic, copper, lead, and mercury) have been found in sediments in
the waterways, along the southwest shore, and near the ASARCO smelter.
Sediment contamination by persistent organic compounds (e.g., PCBs) was
detected in the heavily industrialized waterways (e.g., Hylebos Waterway)
and along the Ruston-Pt.Defiance Shoreline.
During the Commencement Bay N/T RI, four inorganic and six organic
contaminants were detected at concentrations 1,000 times as great as
reference conditions (i.e., those in sediments from nonindustrialized areas
of Puget Sound). Those concentrations were detected in samples from
stations located off the Ruston-Pt. Defiance Shoreline, Hylebos Waterway, and
St. Paul Waterway. Twenty-eight chemicals or chemical groups had concen-
trations 100-1,000 times as great as reference conditions. Contaminants of
concern include metals (e.g., arsenic, lead, mercury, zinc), PCBs, PAH, and
total organic carbon.
Sediment Toxicity--
A number of laboratory tests are available to evaluate the potential
toxicity of contaminated sediments to marine organisms. Many of these tests
are discussed in Chapter 2. The toxicity of Commencement Bay sediments was
initially studied using amphipod bioassays (Swartz et al. 1982a,b). The
waterways were found to contain toxic and nontoxic sediments with hetero-
genous spatial distributions. Sediments with the highest toxicity were
detected near docks, drains, and ditches associated with pollutant sources.
Higher toxicities were observed in intertidal sediments of the waterways
than in sediments from mid-channel and subtidal stations.
During the RI, sediment toxicity was tested using the amphipod and
oyster larvae bioassays. Sediments from 24 of the 52 stations tested had
statistically significant toxicities for one or both of the bioassays when
compared with the reference area (i.e., Carr Inlet). Sediments from 10 of
the stations were toxic in both bioassays. These stations were located in
Hylebos Waterway, City Waterway, St. Paul Waterway, and along the Ruston-
Pt. Defiance Shoreline. In some areas (e.g., Stations SP-14, RS-18, RS-19,
CI-11; see Appendix F for station locations), the sediments were toxic to
the extent that a 90 percent dilution was not sufficient to reduce amphipod
toxicities to reference levels.
Benthic Infauna--
Examination of the benthic community structure provides an in situ
measure of pollution impacts. In the Commencement Bay waterways, the
overall benthic community is regulated by the physical characteristics
1-9
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(e.g., grain size) of the sediment or by environmental stress that may be
associated with toxic contamination or sediment disturbance. However, the
overall high abundances of a mixed polychaete-mollusc assemblage indicate
that severe effects to benthic communities were localized. Areas having
depressed abundances of at least two major taxonomic groups included the
head and middle of Hylebos Waterway, St. Paul Waterway, the head of City
Waterway, Wheeler-Osgood Waterway, and the Ruston-Pt. Defiance Shoreline.
In Sitcum Waterway, single benthic depressions were found at two of three
stations.
Fish Histopathology--
Many recreationally and commercially important species live in contact
with the bottom sediments, resulting in a high potential for uptake of
sediment associated contaminants. The incidence of liver lesions is
greatest in fish from areas with the highest concentrations of sediment-
associated contaminants (Malins et al. 1980). The prevalence of abnor-
malities in organs of shrimp and crabs from Commencement Bay waterways was
particularly high compared with other areas in Puget Sound (Malins et al.
1980).
Histopathological analyses were conducted on the livers of English sole
during the RI. These analyses indicate that prevalences of liver abnormali-
ties such as preneoplastic nodules, megalocytic hepatosis, and nuclear
pleomorphism were significantly elevated compared to prevalences in the
reference area (i.e., Carr Inlet). In comparisons among the eight Commence-
ment Bay RI study areas, prevalences of preneoplastic nodules and nuclear
pleomorphism were significantly elevated only in Middle Waterway, and
prevalences of megalocytic hepatosis were significantly elevated in
Hylebos, Blair, Milwaukee, and Middle Waterways. The prevalence of fish
having one or more of the four hepatic lesions was significantly elevated
in Hylebos, Blair, Sitcum, Milwaukee, and Middle Waterways.
Bioaccumulation--
Concentrations of metals in English sole muscle tissue were relatively
homogeneous among study areas in the Commencement Bay N/T site. The maximum
average concentrations of most metals in fish were less than 2 times the
average reference concentrations. However, the concentrations of copper in
fish tissue were significantly elevated (3-9 times) in fish from Sitcum and
St. Paul Waterways and the Ruston-Pt. Defiance Shoreline. Concentrations of
lead and mercury were elevated in Dungeness crab muscle. Maximum concen-
trations of these metaTs were about 5 times the reference concentrations.
PCBs were detected in all fish and crabs sampled. Maximum concentrations of
PCBs in English sole, which were found in fish from Hylebos and City
Waterways, were about 10 times as great as those found in English sole
caught in the reference area, Carr Inlet.
Concerns exist over the potential human health impacts from the
consumption of local seafood. The Tacoma-Pierce County Health Department
issued a notice in January 1983 advising against the consumption of bottom
fish from Hylebos Waterway and against regular consumption of fish from the
1-10
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other waterways. A second advisory was issued in April 1985 which expanded
the advisory coverage to include the Ruston-Pt. Defiance Shoreline and Carr
Inlet. Data generated in 1984 showed that muscle tissue from English sole
collected at the reference stations in Carr Inlet had low concentrations of
contaminants (Tetra Tech 1985a). Because these data failed to show abnormal
contaminant concentrations, these data were considered suitable for use as
reference data.
1.3.5 Identification of Problem Chemicals and Problem Areas
Sediments in all parts of the N/T area contain concentrations of one or
more toxic contaminants that exceed levels commonly found in Puget Sound
reference areas. During the RI, a multistep decision-making process was
used to 1) define problem sediments and identify areas containing problem
sediments, 2) identify problem chemicals, and 3) prioritize problem areas
for remedial action evaluations. This process resulted in the identification
of 11 high priority problem areas (subsequently consolidated into 9 areas),
which are addressed in this FS report. The decision-making process is
summarized below.
Identification of Problem Areas--
To facilitate the identification of problem areas, the Commencement Bay
waterways and the Ruston-Pt. Defiance Shoreline were divided into 20 segments
based on apparent trends in sediment contamination (Figure 1-2). In order
to characterize each of these 20 segments, indices of contamination were
calculated for each environmental indicator (e.g., sediment contamination,
sediment toxicity, and biological effects). Elevation above reference (EAR)
indices were calculated as the ratio of the value of an indicator in a
particular Commencement .Bay segment to the value of that indicator in the
reference area. For example, the average concentration of arsenic in Sitcum
Waterway sediments (37 mg/kg) was 11 times as great as that in the reference
area, resulting in an EAR of 11.
Carr Inlet was selected as the primary reference area for the Commence-
ment RI/FS. The selection of Carr Inlet for reference values was based on
the proximity of the inlet to Commencement Bay, and the overall lack of
contamination at the reference stations. In addition to Carr Inlet,
uncontaminated stations in Blair Waterway provided reference data for
benthic infauna. Because the physical characteristics of the stations in
Blair Waterway were more similar to those in the problem waterways than to
those in Carr Inlet, Blair Waterway was a more appropriate reference area
for benthic infauna.
EAR values for five indicators (i.e., sediment chemistry, sediment
toxicity, benthic infauna, fish histopathology, and bioaccumulation) were
calculated for each segment. Significant elevations in any three of these
indicators resulted in a segment being designated as a problem area. Use of
this guideline resulted in the designation of problem areas in all Commence-
ment Bay N/T areas and segments.
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HYS6
HYS5
COMMENCEMENT
BAY
HYS4
HYS3
CIS3
CIS1
IOTY«
MMTEIMMV
Figure 1-2. Waterway segments defined during the remedial
investigation for the Commencement Bay study area.
-------
I
I—•
OJ
COMMENCEMENT
BAY
Figure 1-2. (Continued).
-------
Identification of Problem Chemicals--
Synoptic sediment chemistry, sediment toxicity, and benthic infaunal
data were used to predict the concentration of contaminants above which
biological effects would be expected. A sediment toxicity "apparent effects
threshold" (AET) is defined as the contaminant concentration above which
statistically significant toxicity would always be expected. A benthic AET
value is defined as the contaminant concentration above which statistically
significant benthic effects would always be expected. Both values measure
sediment quality as related to observed biological effects. Toxicity and
benthic AET values were defined for each contaminant of concern (i.e.,
chemicals that exceeded all reference conditions) in the N/T area (Tetra
Tech 1985a). The AET values were used to predict the occurrence of
biological effects at sampling stations with only sediment chemistry data
(i.e., sediment toxicity and/or benthic infaunal data were not collected).
Further discussion of AET is provided in Sections 2.2.2.
Problem chemicals within each problem area were assigned a priority on
the basis of two factors: correlation with observed biological effects and
number of stations where concentrations exceeded an AET. Priority 1
chemicals were detected at concentrations greater than an AET and the
spatial distributions of these chemicals corresponded to gradients of
observed toxicity or benthic effects. Priority 2 chemicals were detected at
concentrations greater than an AET at more than one station in a problem
area, but either showed no particular spatial relationship with gradients of
observed toxicity or benthic effects, or insufficient data were available to
evaluate their correspondence with concentration gradients. Priority 3
chemicals were detected at concentrations greater than an AET at only a
single station in a problem area. Chemicals detected at concentrations
below an AET at all stations were not considered problem chemicals.
Prioritization of Areas for Remedial Action Evaluations--
Final prioritization of problem areas for remedial action was determined
on the basis of three criteria:
• Environmental significance
• Spatial extent of contamination
• Confidence in source identification.
Each problem area received a score for each of the three criteria. The
possible scores ranged from 1 to 4, with 4 indicating the highest priority
for potential remedial action. The problem areas with the.highest scores
were determined to warrant evaluation of potential/sediment remedial
actions under Superfund guidelines. Eleven problem areas characterized by
high levels of sediment contamination were assigned the highest priority
during the RI. The final ranking of the problem areas is shown in Table 1-1.
Sediment remedial actions have been evaluated for these problem areas.
1-14
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TABLE 1-1. FINAL RANKING OF PROBLEM AREAS IN THE
COMMENCEMENT BAY REMEDIAL INVESTIGATION3
Segment
Containing
Problem Area"
Environmental
Significance
Confidence
Spatial of Source Total
Extent Identification Score
RSS2
SPS1
CIS1
HYS5
SIS1
HYS1
HYS2
4
4
4
4
4
3
3
3
4
4
4
4
4
3
3
12
11
11
11
11
11
CIS2
MDS1
RSS3
CIS3
HYS4
RSSla (RS-13)
BLS2
MIS1
RSSlb (RS-15)
HYS3
BLS1
HYS6
BLS3
BLS4
4
3
1
3
3
3
2
2
1
1
1
1
1
1
1
3
3
2
2
1
1
1
1
1
1
1
1
1
3
2
4
2
1
1
1
1
1
1
1
1
1
1
8
8
8
7
6
5
5
4
3
3
3
3
3
3
a The possible scores assigned to environmental significance, spatial
extent, and confidence of source identification ranged from 1 to 4. A 4
indicates the highest priority for potential remedial action.
i_
4
0 Problem areas did not always encompass an entire segment. Problem areas in
the segments indicated are listed in order of their total score of environ-
mental significance, spatial extent, and confidence of source identification.
c Identification of potential remedial technologies was conducted for
problem areas with a total score greater than 6 (Tetra Tech 1986b).
Reference: Tetra Tech (1985a).
1-15
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Areas not identified as high priority areas were characterized by less
severe environmental hazard as indicated by lower levels of contamination,
reduced toxicities, and limited biological effects; smaller areas of elevated
problem chemical concentrations (generally less than 10 ac, as compared to
eight of the high priority areas, which were found to have spatial extents
greater than 50 ac); and a limited number of identified sources. Further
discussion of the evaluation process is provided in Tetra Tech (1985a).
Following further investigation during the FS, the 11 problem areas were
recombined into 9 discrete areas of sediment contamination or areas where
contamination can be attributed to a single source or a group of sources
(Figure 1-3). The problem areas discussed in the RI as Hylebos Waterway
Segments 1 and 2 (referred to hereafter as the head of Hylebos Waterway)
have been combined, because the sediment contamination is contiguous and is
attributable, in many cases, to common sources. Part of Hylebos Waterway
Segment 4 was combined with Segment 5 (referred to hereafter as mouth of
Hylebos Waterway) for similar reasons. Segments 2 and 3 of the Ruston-Pt.
Defiance Shoreline (referred to hereafter as Ruston-Pt. Defiance Shoreline)
have also been combined because sediment contamination is attributable to a
single ultimate source (i.e., the ASARCO smelter). The revised designations
for problem areas are summarized in Table 1-2.
1.4 FEASIBILITY STUDY REPORT OVERVIEW
Chapter 2 of this FS provides the technical and institutional basis for
evaluating remediation requirements in Commencement Bay N/T. Section 2.1
provides a description of the technical framework that served as the basis
for the RI/FS process. Section 2.2 provides an indepth discussion of the
establishment of long-term cleanup goals, including goals based on both
environmental and human health risks. Section 2.3 describes how long-term
goals were used to estimate areas and volumes of sediment requiring
remediation. The relationship between the FS and existing regulatory
programs is addressed in Section 2.4. A discussion of future routine
dredging programs in Commencement Bay is provided in Section 2.5.
Potentially applicable technologies for the remediation of contaminated
media are presented and assembled into alternatives in Chapter 3. Both
sediment and source remediation technologies are addressed, with emphasis on
the former. Sediment remediation technologies are presented in Section 3.1.
Source control technologies for contaminated surface water, groundwater,
soil, and air are discussed in Section 3.2. In Sections 3.3 and 3.4, the
various technologies are assembled into sediment remedial alternatives and
the process options within each technology are described. Each alternative
represents a plausible combination of remedial actions for the Commencement
Bay N/T sediment remediation effort. As a whole, the set of alternatives
encompasses the range of general response actions and represents all viable
technologies and process options. Ten remedial alternatives appropriate to
one or more of the nine Commencement Bay N/T problem areas are identified.
The most appropriate alternative for each problem area was recommended from
the ten candidate alternatives.
1-16
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CUMMl MCI Ml. NT
HAY
Highest Priority Problem Sediments
Secondary Priority Problem Sediments
Potential Problem Sediments
(No Confirming Biological Data Available)
Potential Problem Sediments by Historical
Data Only
Chemicals Exceed Apparent Effects
Threshold
Chemicals Below Apparent Effects Threshold
X HYLEBOS
/ \ WATERWAY
Problem Areas Studied lor the Feasibility
Study
— i — - Areas Studied lor the Remedial Investigation
but not the Feasibility Study
WATERWAY
WAIEHWAT
CITV
WATERWAY
Figure 1-3. Relationship between problem areas identified
during the remedial investigation and those studied
for the feasibility study.
-------
i
>—>
CO
RUSTON
TACOMA
Highest Priority Problem Sediments
Secondary Priority Problem Sediments
Potential Problem Sediments
(No Confirming Biological Data Available)
Potential Problem Sediments by Historical
Data Only
Chemicals Exceed Apparent Effects
Threshold
Chemicals Below Apparent Effects Threshold
Problem Areas Studied lor the Feasibility
Study
— — - Areas Studied lor the Remedial Investigation
taut not the Feasibility Study
COMMENCEMENT
BAY
\
Figure 1-3. (Continued).
-------
TABLE 1-2. REVISED DESIGNATIONS FOR PROBLEM AREAS IN
THE COMMENCEMENT BAY NEARSHORE/TIDEFLATS SITE
Previous Designation*
Revised Designation
Hylebos Waterway Segments 1 and 2
(HYSI and HYS2)
Hylebos Waterway Segment 3 and
part of Segment 4 (HYS3 and HYS4)
Part of Hylebos Waterway Segment 4
and Hylebos Waterway Segment 5
(HYS4 and HYS5)
Hylebos Waterway Segment 6 (HYS6)
Blair Waterway Segments 1-4
(BLS1-BLS4)
Sitcum Waterway Segment 1 (SIS1)
Milwaukee Waterway Segment 1 (MIS1)
St. Paul Waterway Segment 1 (SPS1)
Middle Waterway Segment 1 (MDS1)
City Waterway Segment 1 (CIS1)
City Waterway Segment 2 (CIS2)
City Waterway Segment 3 (CIS3)
Ruston-Pt. Defiance Shoreline
Segment 1 (RSSla and RSSlb)
Ruston-Pt. Defiance Shoreline
Segments 2 and 3 (RSS2 and RSS3)
Head of Hylebos Waterway
Low Priority - Not included in FS
Mouth of Hylebos Waterway
Low Priority - Not included in FS
Low Priority - Not included in FS
Sitcum Waterway
Low Priority - Not included in FS
St. Paul Waterway
Middle Waterway
Head of City Waterway
Wheeler-Osgood Waterway
Mouth of City Waterway
Low Priority - Not included in FS
Ruston-Pt. Defiance Shoreline
a Tetra Tech (1985a).
1-19
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Chapter 4 introduces the framework for the detailed analysis of
sediment remedial alternatives. Effectiveness, implementability, and cost
criteria are defined in Sections 4.1, 4.2, and 4.3, respectively.
Section 4.4 presents the framework for identifying the preferred sediment
remedial alternative.
Chapters 5-13 describe the following information for nine high
priority problem areas in the study area:
• A description of the nature and extent of sediment contami-
nation
• An overview of the major sources, with emphasis on the status
of ongoing remedial activities
• An evaluation of the potential success of source control
• A detailed assessment of candidate sediment remedial
alternatives
• A discussion of the selection process and indication of the
recommended alternative
• Integration of source control and sediment remedial action
into an overall cleanup strategy.
Chapter 14 provides a summary discussion of the preferred alternatives
and the sources of uncertainty associated with the assessment procedures and
data used in the FS. References are listed in Chapter 15.
Detailed explanations of certain methods and approaches are presented in
Volume 2 (appendices). Appendix A presents details of the sediment recovery
model, SEDCAM. Appendix B provides detailed descriptions of dredging and
capping technologies. Appendix C provides a summary of specifications from
applicable or relevant and appropriate requirements (ARARs) used to evaluate
potential remedial activities. The method and assumptions used to estimate
costs of the various remedial alternatives are described in Appendix D.
Source loading data are summarized in Appendix E. Estimated rates of input
for each Priority 1 and Priority 2 chemical are presented by problem area,
retaining area designations of the RI (Tetra Tech 1985a). Appendix F is a
set of maps showing the locations of sediment sampling stations in the
subject study area. Appendix G presents the raw sediment data collected for
the FS. Sample collection and laboratory analysis methods are also included
in Appendix G.
The overall framework for implementing the preferred alternative for
each problem area is described in a separate document, the "Commencement Bay
Nearshore/Tideflats Integrated Action Plan" (PTI 1988a). These strategies
were formulated by integrating the proposed sediment remedial action with
recommended source control measures.
1-20
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2.0 TECHNICAL AND INSTITUTIONAL BASIS FOR REMEDIATION
Chapter 2 provides the technical and institutional basis for evaluating
remediation requirements in the Commencement Bay N/T area. Section 2.1
provides a description of the technical framework that served as the basis
for the RI/FS process. Section 2.2 provides a detailed discussion of the
development and use of long-term cleanup goals. Goals based on both
environmental and human health assessments are described. Section 2.3
describes how long-term goals were used to estimate areas and volumes of
sediment requiring remediation. The relationship between the FS and
existing regulatory programs is addressed in Section 2.4. A discussion of
future routine dredging programs in Commencement Bay is provided in
Section 2.5.
2.1 FEASIBILITY STUDY TECHNICAL FRAMEWORK
The Commencement Bay N/T Superfund program is a multistep program
involving a remedial investigation, a feasibility study, source control,
and an integrated action plan. The relationships among these programs are
shown in Figure 2-1.
The Commencement Bay RI was completed in August 1985. Its major
objectives were threefold:
• To identify problem sediments in the waterways and along the
Ruston-Pt. Defiance shoreline
• To identify the particular chemicals associated with those
problem sediments
• To identify potential sources of problem chemicals.
Based on the results of the RI, 11 high priority problem areas were
identified for potential remedial action. These areas were consolidated
into nine problem areas for the Commencement Bay FS evaluation. Although
source identification was somewhat limited by available data, a number of
ongoing sources of contamination were identified.
Following the completion of the RI, two approaches were developed to
address Commencement Bay problems. First, Ecology and U.S. EPA expanded
ongoing source control efforts in the Commencement Bay area. These expanded
efforts focus on controlling or eliminating the ongoing release of chemicals
into high priority problem areas. The source control effort involves a
number of programs, and individual actions have been taken using the most
appropriate program mechanism [e.g., enforcement under the Clean Water Act
(CWA) and the Resource Conservation and Recovery Act (RCRA)]. Examples of
source control actions undertaken in Commencement Bay include the investi-
2-1
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REMEDIAL INVESTIGATION
• Identify Problem Areas
• Identify Problem Chemicals
• Identify Contaminant Sources
FEASIBILITY STUDY
• Identify Remedial Technologies
1 Evaluate Remedial Alternatives
• Recommend Preferred
Alternatives
INTEGRATED ACTION PLAN
• Identify Needed Actions
• Prioritize Needed Actions
• Provide Schedule For
Implementation
Figure 2-1. Relationships among programs
sediment contamination problerr
Commencement Bay N/T site.
2-2
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gation and control of surface water runoff from several log sorting yards in
the area.
The second major effort initiated following the completion of the RI
was the FS. This effort includes the identification, evaluation, and
recommendation of corrective measures for each of the nine high priority
problem areas. The preferred alternatives recommended for each problem area
integrate source control and sediment remedial actions. Natural recovery of
sediments (i.e., degradation or burial of contaminated surface sediments
beneath clean material) is included as a component of the remedial alterna-
tive.
The feasibility of institutional controls and sediment cleanup actions
were evaluated using the standard Superfund evaluation approach. Areas and
volumes of contaminated sediments were estimated based upon an analysis of
sediment chemistry and observed biological effects, and upon the predicted
results of source controls and natural recovery processes. Alternatives
were developed and analyzed in accordance with the most recent U.S. EPA
(1988) guidance. The evaluation process involved consideration of the
effectiveness, implementability, and costs of various remedial alternatives.
This report does not contain detailed engineering and cost evaluations
for individual source control measures. Many of the source control actions
identified herein are currently being implemented by local industries in
response to enhanced Ecology and U.S. EPA regulatory efforts during the last
several years.^ Regulatory actions have resulted in the collection of
additional data that have been incorporated into the FS evaluations. Upon
completion of this FS, source control actions will continue to be handled
under these existing regulatory programs.
The technical approach used in the FS to assess remedial alternatives
for sediment problem areas includes the following components:
• Conduct field investigations to fill data gaps
• Develop sediment cleanup goals
• Develop an analytical approach to 1) establish the relation-
ship between source loading and sediment accumulation of
problem chemicals, and 2) evaluate natural recovery of
sediments following control of sources
• Estimate the feasibility of source control
• Identify and screen candidate sediment remedial alternatives
• Identify preferred alternatives
• Prepare an integrated action plan.
Components of the technical approach are discussed briefly in the following
sections.
2-3
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2.1.1 Field Investigations
The RI (Tetra Tech 1985a) revealed several major data gaps. During
the FS, several approaches were used to collect additional information.
Sediment core data were collected to help distinguish historical from
current sources and to estimate sedimentation rates. Sediment cores were
collected in May 1986 at 22 locations in the high priority problem areas.
Sediment coring locations are identified in Appendix F. These cores were
analyzed for chemical contaminants and 210-Pb. Chemical concentrations were
used to determine depth of contamination and to help define the chronology
of historical contamination in the problem areas. The 210-Pb data were
used to plot radioactive 210-Pb decay curves, which were then used to
estimate sedimentation rates for the selected areas. The summary data
report is included as Appendix G.
Supporting field investigations were conducted to provide additional
information on sources of contamination in the receiving environment.
Ecology's Water Quality Investigation Section investigated the following
four topics, with QA/QC support provided by Tetra Tech, Inc.:
• Potential sources of PCB contamination in Hylebos Waterway
(Stinson et al. 1987)
• Concentration of metals in ASARCO discharges and receiving
waters (Stinson and Norton 1987a)
• Contaminants in Wheeler-Osgood drains and sumps (Stinson and
Norton 1987b)
• 4-Methylphenol in marine sediments of Commencement Bay
(Norton et al. 1987).
Results have been incorporated into the evaluations of individual problem
areas (see Chapters 5-13).
2.1.2 Development of Sediment Cleanup Goals
Under Section 121 of CERCLA/SARA, U.S. EPA is required to select a
remedial action that "... attains a degree of cleanup . . . which assures
protection of human health and the environment . . . ." Protection of human
health and the environment is to be achieved at least in part, by compliance
with the "... appropriate standard, requirement, criteria, or limitation
for contaminants that will remain at the site . . . ." These legally
applicable or relevant and appropriate requirements (ARARs) include federal,
state, local, and tribal laws and regulations. Similar statutory requirements
are contained in the Washington State Model Toxics Control Act. Under state
law, Ecology is required to select those actions that will attain a degree
of cleanup that is protective of human health and the environment. As with
the federal law, remedial actions must, at a minimum, meet the substantive
requirements of other state and federal laws, regulations, and rules.
2-4
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Translating these general directives into specific requirements for the
Commencement Bay N/T project was complicated by the lack of definitive
standards, guidelines, or criteria for defining acceptable levels of
contaminants in marine sediments. The technical approach used to establish
sediment cleanup goals and requirements included the following components:
• Define an acceptable level of environmental and human health
protection
• Develop an approach for translating this conceptual definition
into an administrative framework
• Develop an approach for translating the long-term sediment
cleanup goal into site-specific cleanup requirements
• Define procedures for reviewing cleanup requirements and
incorporating new information to refine estimates of sediment
areas and volumes requiring remediation.
2.1.3 Response of Sediments to Source Control
Following source control, surface sediments will tend to recover (i.e.,
concentrations of contaminants and the composition of biological communities
will not differ statistically from those in similar uncontaminated areas)
naturally through, contaminant degradation, diffusive loss to overlying
water, and deposition of clean sediments. In certain circumstances, source
control and natural recovery of contaminated sediments may represent an
appropriate response to existing sediment contamination problems. Where it
can be shown that the deposit!onal environment and the existing level of
contamination would allow natural recovery, this option would allow gradual
recovery of the benthic community. This option would also minimize
possible adverse impacts associated with redistribution of contaminated
sediments during dredging operations, and would minimize the costs and
technical problems associated with the disposal of contaminated dredged
material. This option is consistent with the guidelines for sediment
cleanup decisions section of the Puget Sound Water Quality Authority's 1989
Management Plan (PSWQA 1988).
Areas of contamination that, following source control, would be
expected to return to acceptable levels in a reasonable timeframe were
predicted using a mathematical model (SEDCAM). Sediment recovery over 5-yr,
10-yr, and 25-yr timeframes were estimated as was long-term sediment
recovery. The technical approach developed to establish the relationship
between source control and sediment recovery includes the following com-
ponents:
• Establishing a mathematical relationship between source
loadings and the level of contamination in surface sediments
2-5
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• Characterizing the depth of the biologically active sediment
surface layer and the natural sedimentation rates in each of
the waterways and along the Ruston-Pt. Defiance Shoreline
using 210-Pb techniques
• Evaluating chemical-specific losses due to biodegradation
and diffusion across the sediment-water interface.
To apply this model, it was necessary to estimate the degree of source
control that is feasible for individual problem areas. Details of the
model and implicit assumptions are described in Appendix A and Tetra Tech
(1987a).
2.1.4 Feasibility of Source Control
Before sediment remedial alternatives can be implemented, it will be
necessary to control the sources of contamination. Potential sources of
contamination are identified and source control technologies are discussed
in the FS report. However, preferred source control alternatives are not
identified. Instead, estimates are provided for the degree of source
control that may be feasible in each problem area. These values were used
to calculate natural sediment recovery following implementation of source
controls.
Estimates of the degree of source control that is feasible for each
problem area were based on known or potential pathways of contamination and
the probable success of implementing all known, available, and reasonable
control technologies. Factors considered in the evaluation include the
number of sources and pathways, the resolution with which these sources and
pathways of contamination were defined, the frequency of contaminant
detection in source monitoring efforts, and average loading values (developed
as the product of observed concentrations and flow volumes).
The feasibility of source control was assumed to be highest for
chemicals with well-defined migration pathways to the problem area. A
maximum of 95 percent source control was assumed feasible for chemicals
discharged from a single source with a well-identified contaminant reservoir
and environmental pathway. A maximum of 80 percent source control was
assumed feasible for chemicals discharged from multiple well-identified
sources, or from a single source with multiple potential migration pathways.
A 70 percent source control level was assumed feasible for chemicals
associated with poorly defined or questionable sources. A 60 percent source
control level was assumed feasible for contaminants associated with storm
drain inputs where major point sources have not been identified in the
drainage basin, and for contaminants from poorly defined sources where it is
unclear whether inputs are ongoing or historical.
2.1.5 Identify and Screen Sediment Remedial Alternatives
Sediment remedial alternatives were developed through the following
steps:
2-6
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• Develop a thorough list of available remedial technologies
for the isolation, excavation, treatment, and disposal of
contaminated sediments
• Conduct an initial screening of available remedial technolo-
gies to identify candidate technologies that may be appropri-
ate for the project area
• Develop specific combinations of appropriate technologies to
define a range of complete sediment remedial alternatives
• Screen candidate sediment remedial alternatives for each
individual problem area to develop a discrete and concise set
of alternatives appropriate for that problem area.
Remedial technologies and corresponding process options were identified
within six response action categories: no action, institutional controls,
in situ containment, removal, treatment, and disposal. Through an initial
screening process, several technologies and many process options were
eliminated as not being appropriate at this time for Commencement Bay N/T
problem areas. The sediment remedial technologies and process options that
passed the initial screening were combined to form 10 remedial alternatives
within five general categories, as follows:
• No action
• Institutional controls
• In situ containment (capping)
• Removal and disposal
Removal/confined aquatic disposal
Removal/nearshore disposal
Removal/upland disposal
• Removal, treatment, and disposal
Removal/solidification/upland disposal
Removal/solvent extraction/upland disposal
Removal/incineration/upland disposal
Removal/Iand treatment.
These 10 alternatives were then evaluated to develop a specific set of
alternatives for each problem area.
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2.1.6 Identification of Preferred Alternatives
A detailed analysis of sediment remedial alternatives and identification
of preferred alternatives is the final stage of the FS process. Evaluation
criteria for the detailed analysis can be grouped into three general cate-
gories: effectiveness, implementability, and cost. For the Commencement
Bay N/T FS, there are four effectiveness criteria: short-term protectiveness;
timeliness; long-term protectiveness; and reduction in contaminant toxicity,
mobility, or volume. Three implementability criteria have been included:
technical feasibility, institutional feasibility, and availability of disposal
facilities. Cost criteria were divided into initial costs, and operation
and maintenance (O&M) costs. Initial costs include those for design, prepara-
tion of specifications, and construction. O&M costs include those for environ-
mental monitoring. A cost analysis was performed to estimate the initial
costs of each alternative and the present value of a 30-yr monitoring program.
A full analysis of effectiveness and implementability of each alternative
is presented in a narrative matrix for each problem area. Summary tables,
in which each alternative is rated high, moderate, or low in the seven major
evaluation criteria have also been prepared. Costs are shown in the latter
tables. Based on this evaluation, a preferred alternative was identified
and proposed for sediment remediation in each problem area.
The preferred alternatives will be evaluated during a public review
period. Following public review, correction of sediment contamination problems
will be implemented according to a performance-based Record of Decision (ROD).
The ROD will specify performance criteria (e.g., attainment of specific
cleanup criteria), but will not require that a specific technology be used
to conduct the cleanup. Since sediment cleanup (i.e., source control and
sediment remedial action) may span 5 to 10 yr, new and possibly more effective
techniques may become available after the ROD. In addition, smaller projects
(e.g., pier development or maintenance dredging) within problem areas are
anticipated prior to scheduled remedial action under Superfund. These smaller
projects would need to be conducted in a manner consistent with the performance
criteria specified in the ROD, but not necessarily according to the recommended
technology. This approach provides the flexibility to use the most appropriate
technology available at the time cleanup occurs as long as it can be shown,
during the detailed engineering phase of the project, that the technology
will be at least as effective in attaining the cleanup criteria as the tech-
nology recommended in the ROD. Post-ROD activities will be implemented
according to the Integrated Action Plan (PTI 1988a) (Section 2.1.6).
2.1.7 Integrated Action Plan
Development and implementation of preferred sediment remedial alterna-
tives must be coordinated with source control to maintain acceptable
sediment quality following remediation. Institutional requirements, source
control measures, and sediment remedial actions are incorporated in the
Commencement Bay Integrated Action Plan (IAP) (PTI 1988a) to identify,
prioritize, and integrate remedial activities. The overall objective of the
plan is to ensure that risks to human health and the environment are
eliminated in a timely and cost-effective manner.
2-8
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2.2 IDENTIFICATION OF LONG-TERM CLEANUP GOALS
2.2.1 Background
The purpose of Superfund actions is to protect human health and the
environment from hazards associated with the release or threatened release
of hazardous substances. A major issue in developing sediment cleanup goals
for the Commencement Bay N/T Superfund site is the determination of the
degree of protection that is necessary and appropriate.
Translating the guidance regarding ARARs provided under Section 121 of
the CERCLA/SARA (see Section 2.1.2) into specific requirements for the
Commencement Bay N/T project was complicated by the lack of definitive
standards, guidelines, or criteria for defining acceptable levels of
contaminants in marine sediments. However, the Puget Sound Water Quality
Authority Management (1989) Plan (PSWQA 1988) specified a number of goals
and policies that are applicable to the Commencement Bay area. For purposes
of defining sediment cleanup goals and requirements, two program elements
are of particular importance: Standards for Classifying Sediments Having
Adverse Effects (Element P-2), and Guidelines for Sediment Cleanup Decisions
(Element S-7).
Element P-2 requires Ecology to develop and adopt by regulation,
standards for identifying and designating sediments that have observable
acute or chronic adverse effects on biological resources or pose a signifi-
cant health risk to humans. The standards for defining "sediments that have
acute or chronic adverse effects" may use chemical, physical, or biological
tests, and shall clearly define pass/fail standards for any tests. Initial
standards may deal exclusively with biological effects, but shall be revised
to include human health concerns as this information becomes available. The
standards are to be used to limit discharges through the NPDES (Element P-7),
stormwater (Element SW-4), and nonpoint programs; to identify sites with
sediment contamination (Element S-8); and to limit the disposal of dredged
material (Element S-4). Element S-7 requires Ecology to develop guidelines
for deciding when to implement sediment remedial actions. The guidelines
should consider deadlines for making decisions, natural recovery of
sediments, procedures for determining priorities for action (including
consideration of costs), and trigger levels for defining sediments that
require expedited remedial action. Trigger levels may be higher than the
sediments-having-adverse-effects levels developed under Element P-2.
The sediment quality goal in Element P-2 (no acute or chronic adverse
effects on biological resources or significant health risk to humans) was
used to define the long-term sediment quality goal in Commencement Bay. As
in other parts of Puget Sound, this sediment cleanup goal is meant to
establish levels of sediment contamination that would be acceptable
throughout Commencement Bay. It is a long-term goal to be achieved through
numerous actions over a period of 10 to 15 yr. The long-term goal has not
been modified to take into consideration factors such as cost and technical
feasibility. Consequently, it serves as a yardstick for evaluating and
selecting the requirements for individual actions where these and other
factors are considered. The methods and factors associated with translating
2-9
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this goal into individual requirements will vary depending on the type of
action, statutory authorities, and site-specific considerations, as
discussed in Section 2.3.
There are a number of technical approaches for defining sediments that
meet the long-term cleanup goal. Available approaches have been divided
into the following two groups: 1) those concerned with environmental
effects (Section 2.2.2), and 2) those concerned with human health effects
(Section 2.2.3).
2.2.2 Evaluation of Environmental Effects
The sediments of Commencement Bay host a large diversity of benthic
organisms that may be directly influenced by sediment contaminants.
Sediment contaminants may result in acute or chronic impacts to those
organisms. In addition to potential impacts to benthic organisms, fish and
crabs that live in close association with the sediment and perhaps feed on
benthic organisms may be affected. Therefore, the evaluation of environ-
mental effects on resident biota provides a suitable basis for development
of long-term sediment quality goals. Approaches for development of long-
term goals based on environmental effects (i.e., benthic communities, and
sediment toxicity) are summarized below. The technical approach selected
for use in the FS (i.e., the AET), and the rationale for selecting it are
described in Section 2.2.2. Administrative procedures that will be used to
define the long-term goal are described in Section 2.2.4. This discussion
addresses chemical and biological testing requirements and interpretation
guidelines. Procedures for reviewing cleanup estimates and incorporating
new information to refine estimates of sediment areas and volumes requiring
remediation are described in Section 2.2.5.
Sediment Quality Goals - Review of Available Approaches--
Ideal ly, sediment quality values and sediment management decisions would
be supported by definitive cause-and-effect information relating specific
chemicals to biological effects in various aquatic organisms and to
quantifiable human health risks. However, to date, very little information
of this type is available, and it is unlikely that additional information
will be available in the near future. In the interim, in the interest of
protecting human health and the environment, regulatory agencies must
proceed with sediment management decisions based on the best information
available.
The ability to develop sediment cleanup goals for the Commencement Bay
N/T site was initially limited due to a lack of appropriate regulatory
standards or guidelines for evaluating the quality of the marine environ-
ment. The ability to assess sediment quality in a technically reliable and
legally defensible manner was considered a necessary component of a complete
plan for remedial action, and was required to make the following management
decisions:
2-10
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• Identify problem chemicals
• Establish a link between contaminated sediments and sources
• Provide a predictive tool for cases in which site-specific
biological testing results were not available
• Enable designation of problem areas within the site
• Provide a consistent basis on which to evaluate sediment
contamination and to separate acceptable from unacceptable
conditions
• Provide an environmental basis for triggering sediment
remedial action
• Provide a reference point for establishing a cleanup goal
• Evaluate the need for and success of source control.
In the past decade, several federal, regional, and state agencies have
developed numerical criteria or assessment methods for evaluating contami-
nation in sediments and dredged material. Most early efforts at developing
criteria were based on comparing chemical concentrations in contaminated
areas to those in reference areas, and did not directly consider biological
effects. More recently, approaches to evaluating sediment quality have
focused on determining relationships between sediment contaminant concentra-
tions and adverse biological impacts.
Various approaches were evaluated for possible use in guiding management
decisions under PSDDA (Tetra Tech 1986a). The conclusions of this indepen-
dent study have been reviewed in the context of the Commencement Bay N/T
project, and have also been reviewed for application in other Puget Sound
programs (Tetra Tech 1986a; Lyman et al. 1987; Battelle 1988; and Chapman,
in review). The following approaches were evaluated:
• Field-based approaches
Reference area
Field-collected sediment bioassay
Screening level concentration (SLC)
Sediment quality triad (Triad)
Apparent effects threshold (AET)
2-11
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• Laboratory/theoretically-based approaches
Water quality criteria/interstitial water
Equilibrium partitioning (sediment-water)
Equilibrium partitioning (sediment-biota)
Spiked sediment bioassay.
These approaches are briefly described in Table 2-1. Field-based
approaches rely on empirical chemical and/or biological measurements of
sediments to establish sediment quality values. Some of these approaches
are either purely chemical (reference area approach) or biological
(field-collected sediment bioassay approach) in nature. Other approaches
such as SLC, Triad, and AET correlate biological responses (e.g., field-
collected sediment bioassays, in situ biological effects observed in
organisms associated with sediments) and chemical concentrations measured in
sediments to develop sediment quality values. Laboratory/theoretically-based
approaches rely on extrapolation of water quality criteria to sediments,
models of environmental interactions (e.g., sediment-water equilibrium
partitioning) or extrapolation of laboratory cause-effect studies to develop
sediment quality values.
In the 1986 study, the water quality criteria, spiked bioassay, and
field bioassay approaches were not considered appropriate for further
consideration as stand-alone methods. Water quality criteria are integrated
into the sediment-water equilibrium partitioning approach. The field
bioassay approach was considered as part of the AET approach and could not
generate chemical-specific criteria in its simplest form. Sufficient data
were not available to evaluate the spiked bioassay approach. The remaining
five approaches were evaluated, using several management and technical
criteria (Tetra Tech 1986a). For the Commencement Bay N/T project, the
following criteria were used:
• Management considerations
Applicability to existing and anticipated sediment
management programs at the site
Feasibility of full implementation in the very near term
Environmental protectiveness (i.e., reliability in
predictions of adverse effects)
Regulatory defensibility (i.e., supporting weight of
evidence)
Cost of initial sediment quality value development
Cost of routine application as a regulatory tool
2-12
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TABLE 2-1. APPROACHES EVALUATED FOR
ESTABLISHING SEDIMENT QUALITY VALUES
Approach
Concept
Reference Area
Field Collected Sediment
Screening Level Concentra-
tion (SLC)
Sediment Quality Triad
(Triad)
Apparent Effects Threshold
(AET)
Water Quality Criteria/
Interstitial Water
Sediment quality values are based on chemical
concentrations in a pristine area or an area
with acceptably low levels of contamination.
Relationships between chemical concentrations
and biological responses are established by
exposing test organisms to field-collected
sediments with measured contaminant concentra-
tions.
The SLC approach estimates the sediment
concentration of a contaminant above which
less than 95 percent of the total enumerated
species of benthic infauna are present. SLC
values .are empirically derived from paired
field data for sediment chemistry and species-
specific benthic infaunal abundances.
The Triad approach consists of coincident
measurements of sediment contamination,
sediment toxicity, and benthic infauna
community structure. This approach is based
upon the observation that each component
complements and adds to the information
provided by the other two components in
assessments of pollution-induced environmental
degradation. the hypothesis underlying this
concept is that no individual component of the
triad can be used to predict the results of
the measurements of the other components.
An AET is the sediment concentration of a
contaminant above which statistically
significant biological effects (e.g., amphipod
mortality in bioassays, depressions in the
abundance of benthic infauna) would always be
expected. AETs are empirically derived from
paired field data for sediment chemistry and a
range of biological effects indicators.
Contaminant concentrations in
water are measured directly and
U.S. EPA water quality criteria.
interstitial
compared with
2-13
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TABLE 2-1. (Continued)
Equilibrium Partitioning
(Sediment-Water)
Equilibrium Partitioning
(Sediment-Biota)
Spiked Sediment Bioassay
A theoretical model is used to describe the
equilibrium partitioning of a contaminant
between sedimentary organic matter and
interstitial water. A sediment quality value
for a given contaminant is the organic carbon
normalized concentration that would correspond
to an interstitial water concentration
equivalent to the U.S. EPA water quality
criterion for the contaminant.
Acceptable contaminant body burdens for
benthic organisms are based on existing
regulatory limits. Sedimentary contaminant
concentrations that would correspond to these
body burdens under thermodynamic equilibrium
are established as sediment quality values.
Dose-response relationships are established by
exposing test organisms to sediments that
have been spiked with known amounts of
chemicals or mixtures of chemicals. Sediment
quality values are determined for sediment
bioassays in the manner that aqueous bioassays
were used to establish U.S. EPA water quality
criteria.
2-14
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• Technical considerations
Data requirements for initial sediment quality value
development and the current availability of data
Data requirements for routine application as a regulatory
tool
Ability to develop chemical-specific sediment quality
values
Ability to develop sediment quality values for a wide
range of chemicals (e.g., metals; nonionic organic
compounds; ionizable organic compounds)
Current availability of values for a wide range of
problem chemicals in Commencement Bay
Ability to incorporate influence of chemical mixtures in
sediments
Ability to incorporate a range of biological indicator
organisms
Ability to incorporate direct measurement of sediment
biological effects
Applicability of predictions to historical sediment
chemistry data
Ease and extent of field verification in Puget Sound.
Three approaches were identified as most promising in the Tetra
Tech (1986a) study and selected for further evaluation. They included the
SLC, AET, and sediment-water equilibrium partitioning approaches. These
remaining approaches were compared in a field verification test designed to
assess their ability to predict observed adverse impacts in actual environ-
mental samples collected from Puget Sound. Field verification using diverse
environmental samples was an important element of the evaluation of each
approach because none of the available approaches are fully capable of
addressing all concerns about interactive effects among chemicals and other
factors that may be important in field-contaminated sediments. Sediment
quality values were generated according to each approach, and were compared
to biological effects data developed for the sediment samples. The SLC
approach could not be adequately tested using the existing data, and was
subjected to a limited evaluation.
Specific measures of predictive reliability were developed to object-
ively assess the approaches to sediment quality value generation. The
measures focused on the binary (i.e., impacted vs. nonimpacted) predictions
of sediment quality values (if, for a given station, one or more chemicals
2-15
-------
exceeded their sediment quality values, then the station was predicted to
have impacts). The measures of reliability were defined as follows:
• Sensitivity in detecting environmental problems (i.e., are
all biologically impacted sediments identified by the
predictions of the chemical sediment criteria?)
• Efficiency in screening environmental problems (i.e., are
only biologically impacted sediments identified by the
predictions of the chemical sediment criteria?).
As a measure of reliability, sensitivity was defined as the proportion of
all stations exhibiting adverse biological effects that are correctly
predicted using sediment quality values. Efficiency was defined as a
proportion of all stations predicted to have adverse biological effects that
actually are impacted. The concepts of sensitivity and efficiency are
illustrated in Figure 2-2.
The sediment quality values developed according to the AET approach
were found to provide greater overall predictive reliability than those
derived by the equilibrium partitioning approach. For example, depending on
the biological indicator being tested, the AET approach correctly identified
between 54 and 94 percent of the field stations exhibiting biological
impacts (sensitivity), and had an efficiency of 33-100 percent. In
comparison, the equilibrium partitioning approach correctly predicted from
13 to 43 percent of the impacted stations (sensitivity), and had an
efficiency of 33-100 percent. A recent study of the AET approach using a
larger data set (PTI 1988c) demonstrated sensitivity similar to that
observed in 1986, but with generally higher efficiency (typically >60
percent).
The AET Approach--
Rationale for Selection of AET--Based on consideration of management
and technical criteria and on results of the verification exercise with
field-collected data, the AET approach has been selected and confirmed as
the preferred method for developing sediment quality goals in Commencement
Bay. At this time, the AET approach can be used to provide chemical-
specific sediment quality values for the greatest number and widest range of
chemicals of concern in Commencement Bay and throughout Puget Sound. AET
can also be developed for a range of biological indicators, including
laboratory-controlled bioassays and in situ benthic infaunal analyses (the
indicators for which data are available are discussed later in this
section). An additional advantage of using existing AET for the Commencement
Bay N/T FS is that RI data constitute a relatively large proportion of the
data set used to generate AET values. The AET approach has also been
selected for application in other Puget Sound regulatory programs, including
the PSWQA Plan, PSDDA, and PSEP (Section 2.4).
AET Development—An AET is defined as the sediment concentration of a
given chemical above which statistically significant (PO.05) biological
effects are always expected. In this section, the procedure for developing
2-16
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MEASURES OF RELIABILITY
SENSITIVITY = C/B x 100 = 5/8 x 100 = 63%
EFFICIENCY = C/A x 100 = 5/7 x 100 = 71%
FOR A GIVEN BIOLOGICAL INDICATOR:
A All stations predicted to be impacted
B All stations known to be impacted
C All stations correctly predicted to be impacted
Figure 2-2. Measures of reliability (sensitivity and efficiency).
2-17
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chemical-specific AET is described, and the AET concept is discussed as it
relates to the interpretation of chemical and biological data in field-
collected sediments. AET generation is a conceptually simple process that
incorporates some of the complexity of biological-chemical relationships in
the environment without relying upon assumptions about the mechanistic
(i.e., cause-and-effect) nature of these relationships. The concept of the
AET is presented in this section with little reference to specific chemicals
or specific biological tests, because the approach is not inherently limited
to specific subsets of these variables.
The focus of the AET approach is on identifying concentrations of
contaminants that are associated exclusively with sediments exhibiting
statistically significant biological effects relative to reference sediments.
As follows, the calculation of the AET for each chemical and biological
indicator is straightforward:
1) Collect "matched" chemical and biological effects data--
Conduct chemical and biological effects tests on subsamples
of the same field sample (to avoid unaccountable losses of
benthic organisms, benthic infaunal and chemical analyses are
conducted on separate samples collected concurrently at the
same location)
2) Identify "impacted" and "nonimpacted" stations—Statisti-
cally test the significance of adverse biological effects
relative to suitable reference conditions for each sediment
sample and biological indicator; suitable reference conditions
are established by sediments containing very low or undetec-
table concentrations of any toxic chemicals
3) Identify AET using only "nonimpacted" stations — For each
chemical, the AET can be identified for a given biological
indicator as the highest detected concentration among
sediment samples that does not exhibit a statistically
significant effect (if the chemical is undetected in all
nonimpacted samples, then no AET can be established for that
chemical and biological indicator)
4) Check for preliminary AET—Verify that statistically
significant biological effects are observed at a chemical
concentration higher than the AET; otherwise the AET is only
a preliminary estimate or may not exist
5) Repeat steps 1 through 4 for each biological indicator.
A pictorial representation of the AET approach for two chemicals is
presented in Figure 2-3 based on results for the amphipod toxicity bioassay.
Two subsets of the data from all sediments chemically analyzed and subjected
to an amphipod bioassay are represented by bars in the figure. The
following information is presented in Figure 2-3:
2-18
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LEAD
HU atUIMCMI lUAIlslll
.:..|::;~TT^ . s...:^:.:..i. .. _ . .
y^J'ti/^'/^/^/l/^Sp';////,
\ \
SP-15 SP-14
0 ppm
I , , , . i ,| , ,
10 100
t— POTENTIAL
EFFECT
THRESHOLD
. ...
OBbLRVtU
/ /' y» '* »
RS-19
700 ppm
i
| 1000
APPARENT
AMPHIPOD
TOXICITY
THRESHOLD
J
I!
RS-18J
I
I
6300 ppm
31 i-i
10,000
OBSERVED
LEVEL AT A
BIOLOGICAL
STATION
CONCENTRATION (mg/kg DW)
4-METHYLPHENOL
OH
(o)
NU ^tUIMtNl IUA1LJIY *•
• •• • • •«• • m* MI •«•• •*• • ••• • i
Y / / ' /////'!/' ' / ! / /' / ////'// ///' /// ''//' ' ' // / '/'/
t,--1 / ' ///y/, /// /y'/'^////^ / /y/>/»*»'^* ! / // //T x* ' ' / *'*f / * *
1 1 ' t
RS-19 RS-18 SP-15
1200 ppb
\
t!
SP-14 |
1
1
1
1
U10 100 1000 10,000 96,000
L 'I
*• POTENTIAL APPARENT MAXIMUM -J
EFFECT AMPHIPOD OBSERVED
THRESHOLD TOXICITY LEVEL AT A
THRESHOLD BIOLOGICAL
STATION
CONCENTRATION (ng/kg DW)
U = Undetected a\ detection limit shown
Figure 2-3. The AET approach to sediments tested for lead and
4-methylphenol concentrations and amphipod mortality
during bioassays.
2-19
-------
• Sediments that did not exhibit statistically significant
(P=0.05) amphipod toxicity relative to reference conditions
("nonimpacted" stations)
• Sediments that did exhibit statistically significant (P=0.05)
amphipod toxicity in bioassays relative to reference
conditions ("impacted" stations).
The horizontal axes in Figure 2-3 represent sediment concentrations of
chemicals (lead or 4-methylphenol) on a log scale. The AET is established
by the highest concentration at a station without observed biological
effects. For the toxicity bioassay under consideration, the AET for lead is
the highest lead concentration corresponding to sediments that did not
exhibit significant toxicity (the top bar for lead in Figure 2-3). Above
this AET for lead, significant amphipod toxicity was always observed in the
data set. The AET for 4-methylphenol was determined analogously.
Interpretation of the AET--An AET corresponds to the sediment concentra-
tion of a chemical above which all samples for a particular biological
indicator were observed to have adverse effects. Thus, the AET is based on
noncontradictory evidence of biological effects. Data are treated in this
manner to reduce the weight given to samples in which factors other than the
contaminant examined (e.g., other contaminants, environmental variables) may
be responsible for the biological effect.
Using Figure 2-3 as an example, sediment from Station SP-14 exhibited
severe toxicity, potentially related to a greater elevated level of
4-methylphenol (7,400 times reference levels). The same sediment from
Station SP-14 contained a relatively low concentration of lead that was well
below the AET for lead (Figure 2-3). Despite the toxic effects associated
with the sample, sediments from many other stations with higher lead
concentrations than SP-14 exhibited no statistically significant biological
effects. These results were interpreted to suggest that the effects at
Station SP-14 were potentially associated with 4-methylphenol (or a
substance with a similar environmental distribution), but were less likely
to be associated with lead.
A converse argument can be made for lead and 4-methyl phenol in
sediments from Station RS-18. In this manner, the AET approach helps to
identify measured chemicals that are potentially associated with observed
effects at each biologically impacted site and eliminates from consideration
chemicals that are less likely to be associated with effects (i.e., the
latter chemicals have been observed at higher concentrations at other sites
without associated biological effects). Based on the results for lead and
4-methylphenol, effects at two of the impacted sites shown in the figure may
be associated with elevated concentrations of 4-methylphenol, and effects at
three other sites may be associated with elevated concentrations of lead (or
similarly distributed contaminants).
These results illustrate that the occurrence of biologically impacted
stations at concentrations below the AET of a single chemical does not imply
that AET in general are not protective against biological effects, only that
2-20
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single chemicals may not account for all stations with biological effects.
By developing AET for multiple chemicals, a high percentage of all stations
with biological effects are accounted for with the AET approach, as has been
demonstrated in validation tests with large matched biological and chemical
data sets (Tetra Tech 1986a; PTI 1988b,c).
Dose-Response Relationships and AET--The AET concept is consistent with
empirical observations in the laboratory of dose-response relationships
between increasing concentrations of individual toxic chemicals and
increasing biological effects. A simple hypothetical example of such single-
chemical relationships is shown for chemicals X and Y in Figure 2-4. In the
example, data are shown for laboratory exposures of a test organism to
sediment containing only increasing concentrations of chemical X, and
independently, for exposures to sediment containing only increasing
concentrations of chemical Y. The magnitude of toxic response in the
example differs for the two chemicals, and occurs over two different
concentration ranges. It is assumed that at some level of response (e.g.,
>25 percent) the two different responses can be distinguished from reference
conditions (i.e., responses resulting from exposure to sediments containing
very low or undetectable concentrations of any toxic chemicals).
These single-chemical relationships cannot be proven in the field
because organisms are exposed to complex mixtures of chemicals in environ-
mental samples. In addition, unrelated discharges from different sources
can result in uncorrelated distributions of chemicals in environmental
samples. To demonstrate the potential effects of these distributions,
response data are shown in Figure 2-5 for random association of chemical X
and Y using the same concentration data as in Figure 2-4. The data have
been plotted according to increasing concentrations of chemical X, and the
same dose-response relationship observed independently for the two chemicals
in the laboratory has been assumed. The contributions of chemicals X and Y
to the toxic response shown for these simple mixtures is intended only for
illustration purposes to enable direct comparison to the relationships shown
in Figure 2-4; interactive effects are not considered in this example.
In Figure 2-5, a significant response relative to reference conditions
would result whenever elevated concentrations of either chemical X or
chemical Y occurred in a sample. Because of the random association of Y
with X in these samples, the significant responses would appear to occur
randomly over the lower concentration range of chemical X. The classifica-
tion of the responses shown in Figure 2-5 into significant and nonsignificant
groups (i.e., >25 percent response for either chemical) results in generation
of Figure 2-6.
Figure 2-6 represents the appearance of the environmental results when
ranked according to concentrations of chemical X using these data. Below
the AET for chemical X, significant toxicity is produced by elevated
concentrations of chemical Y, which is randomly associated with the
distribution of chemical X. Above the AET for chemical X, significant
toxicity is always produced by elevated concentrations of chemical X,
although in some samples, elevated concentrations of chemical Y also
contribute to the overall toxicity. The AET for chemical X corresponds
2-21
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ro
I
ro
ro
Bioassay Response
100
Chemical X
Chemical Y +
0
r
Significant Toxicity
Increasing X or Y >
Reference: PTI(1988c).
Figure 2-4. Hypothetical example of dose-response relationship resulting from laboratory
exposure to single chemicals X and Y.
-------
Bioassay Response
100
Chemical X
Chemical Y
ro
i
ro
u>
0
Significant Toxicity
Increasing X -
Reference: PTI(1988c).
Figure 2-5. Hypothetical example of toxic response resulting from exposure to environmental
samples of sediment contaminated with chemicals X and Y.
-------
ro
t
ro
Bioassay Response
100
Increasing X or Y
Significant Toxicity
No Toxicity
Bioassay Response
100
0
Increasing X
AET
1
OD O OOO O O
Increasing X >
NOTE: Figures 2-4 and 2-5 are shown for comparison; dashed line indicates level of significant toxicily.
Reference: PTI(1988c).
Figure 2-6. Hypothetical example of AET calculation for chemical X based on classification of
significant and nonsignificant responses for environmental samples contaminated
with both chemicals X and Y.
-------
conceptually, in this simple example, to the concentration in Figure 2-4 at
which a significant difference in response was observed in the laboratory for
chemical X.
In environmental samples that contain complex mixtures of chemicals, a
monotonic dose-response relationship such as in this simple two-chemical
example may not always apply. For example, a consistently increasing
biological response may not always occur at increasing concentrations of a
chemical above its AET. Such observations could indicate that the AET is
coincidental (i.e., that the observed toxicity in some or all samples above
the AET is unrelated to the presence of that chemical), or that changing
environmental factors in samples exceeding an AET obscure a monotonic dose-
response relationship. Such factors are discussed in the following section.
Influence of Environmental Factors on AET Interpretation—Although the
AET concept is simple, the generation of AET values based on environmental
data incorporates many complex biological-chemical interrelationships. For
example, the AET approach incorporates the net effects of the following
factors that may be important in field-collected sediments:
• Unmeasured chemicals and other unmeasured, potentially
adverse variables
• Interactive effects of chemicals (e.g., synergism, antagonism,
and additivity)
• Matrix effects and bioavailability [i.e., phase associations
between contaminants and sediments that affect bioavailability
of the contaminants, such as the incorporation of polycyclic
aromatic hydrocarbons (PAH) in soot particles].
The AET approach cannot distinguish and quantify the contributions of
unmeasured chemicals, interactive effects, or matrix effects in environmental
samples, but AET values may be influenced by these factors. To the extent
that the samples used to generate AET are representative of samples for
which AET are used to predict effects, the above environmental factors may
not detract from the predictive reliability of AET. Alternatively, the
infrequent occurrence of the above environmental factors in a data set used
to generate AET could detract from the predictive reliability of those AET
values. If confounding environmental factors render the AET approach
unreliable, this should be evident from validation tests in which biological
effects are predicted in environmental samples. Tests of AET values
generated from Puget Sound data (Tetra Tech 1986a; PTI 1988c) indicate that
the approach is relatively reliable in predicting biological effects despite
the potential uncertainties of confounding environmental factors.
Although the environmental factors discussed above can influence the
generation of field-based sediment quality values such as AET, they may also
influence the application of all sediment quality value approaches for the
prediction of adverse biological effects. For example, sediment quality
values based on laboratory sediment bioassays spiked with single chemicals
would not be susceptible to the effects of the environmental factors listed
2-25
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above. However, in applying such values to field-collected samples,
predictions of biological effects could be less successful to the extent
that interactive effects, unmeasured chemicals, and matrix effects occur in
the environment. The nature of the relationships between AET values and
confounding environmental factors is discussed in the remainder of this
section.
Unmeasured Toxic Chemicals and AET--In general, the effect of unmeasured
chemicals on the predictive success of the AET approach is a function of
the degree of covariance (i.e., similarity in environmental distribution) of
measured and unmeasured chemicals.
If an unmeasured chemical (or group of chemicals) varies consistently
in the environment with a measured chemical, then the AET established for
the measured contaminant will indirectly apply to, or result in the
management of, the unmeasured contaminant. In such cases, a measured
contaminant would act as a surrogate for an unmeasured contaminant (or group
of unmeasured contaminants). Because all potential contaminants cannot be
measured routinely, management strategies must rely to some extent on
"surrogate" chemicals.
If an unmeasured toxic chemical (or group of chemicals) does not always
covary with a measured chemical (e.g., if a certain industry releases an
unusual mixture of contaminants), then the effect should be mitigated if a
sufficiently large and diverse data set is used to establish AET. Use of a
data set comprising samples with diverse chemical assemblages and wide-
ranging chemical concentrations would decrease the likelihood that an
unrealistically low AET would be set. Because AET are set by the highest
concentration of a given chemical in samples without observed biological
effects, AET will not be affected by less contaminated samples in which
unmeasured contaminants cause biological effects.
If an unmeasured toxic chemical does not covary with any of the
measured chemicals, then it is unlikely that the AET (or any other chemical-
specific approach) could predict impacts at stations where the chemical is
inducing toxic effects. The frequency of occurrence of stations with
biological effects but no chemicals exceeding AET has been the subject of
extensive validation tests (Tetra Tech 1986a; PTI 1988c).
Interactive Effects and AET--AET uncertainty is increased by the
possibility of interactive effects; the increase in uncertainty is expected
to be less pronounced when large data sets collected from diverse areas are
used to generate AET. Additivity and synergism can produce a comparatively
low AET for a given chemical by causing impacts at concentrations that would
not cause impacts in the absence of these interactive effects. This would
effectively reduce the pool of nonimpacted stations used to generate AET.
This effect should be reduced if a diverse database is used such that
chemicals occur over a wide range of concentrations at stations where
additivity and synergism are not operative. For chemicals that covary
regularly in the environment (e.g., fluoranthene and pyrene), even a large,
diverse database will not reduce the effects of additivity and/or synergism
on AET generation. The resulting AET values for such chemicals may be
2-26
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reliable in predicting biological effects in environmental samples although
not representative of the toxicities of the chemicals acting independently.
Antagonism will produce comparatively high AET values if (and only if)
the AET is established at a station where antagonism occurs. A large,
diverse database could not rectify this elevation of AET if the station at
which antagonism occurred was the nonimpacted station with the highest
concentration (i.e., the station setting an AET). An AET set by a station
at which antagonism occurred would not be representative of the toxicity of
the chemical acting independently.
Empirical approaches such as the AET do not provide a means for
characterizing interactive effects. Only laboratory-spiked sediment
bioassays offer a systematic and reliable method for identifying and
quantifying additivity, synergism, and antagonism. A great deal of research
effort would be required to test the range of chemicals potentially
occurring in the environment (both individually and in combination), a
sufficiently wide range of organisms, an a wide range of sediment matrices
to establish criteria. In addition, the applicability of bioassays
conducted with laboratory-spiked sediments to environmentally-contaminated
sediments requires further testing.
Matrix Effects and Bioavailability—Geochemical associations of
contaminants with sediments that reduce bioavailability of those contaminants
would affect AET analogously to antagonistic effects (i.e., they would
increase AET relative to sediments in which this factor was not operative).
Sediment matrices observed in Commencement Bay that may reduce bioavailabil-
ity of certain contaminants include slag material (containing high concen-
trations of various metals and metalloids, such as copper and arsenic), and
coal or soot (which may contain high concentrations of largely unavailable
PAH, as opposed to oil or creosote, in which PAH would be expected to be far
more bioavailable). Many kinds of matrices may occur in the environment and
a large proportion may be difficult to classify based upon appearance or
routinely measured sediment variables. Hence, the use of matrix-specific
data sets to generate AET, although desirable, would be difficult to
implement. Data treatment guidelines to address the possibility of matrix
effects are discussed in PTI (1988c).
The AET Database--AET can be expected to be most predictive when
developed from a large database with wide ranges of chemical concentrations
and a wide diversity of measured contaminants. During the RI, AET were
generated for a combined measure of sediment toxicity (i.e., either amphipod
mortality or oyster larvae abnormality), and benthic infaunal depressions
(at phylum or class levels of taxonomic classification). These AET values
were based on data from 50-60 stations. In a more recent project for PSDDA
and PSEP, AET were generated with a larger database (190 samples, including
Commencement Bay data) for individual measures of toxicity (i.e., amphipod
mortality, oyster larvae abnormality, and Microtox bioluminescence bio-
assays), and benthic infaunal depressions (at phylum or class taxonomic
levels) (Tetra Tech 1986a). During the Eagle Harbor Preliminary Investiga-
tion (Tetra Tech 1986b), matched biological and chemical data from 10 Eagle
Harbor stations were added to the existing 190-sample Puget Sound database.
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Additional data sets from Elliott Bay, Everett Harbor, and associated
reference areas have most recently been incorporated into the AET database
(PTI 1988c). AET developed from this 334-sample data set were used to
establish sediment cleanup goals and to assess the feasibility of sediment
remedial actions in Commencement Bay. Detailed descriptions of data
treatment for this data set (including the statistical analyses used for
each biological indicator) are presented in PTI (1988b,c).
The following is an overview of the four biological tests used to
generate AET and their ecological relevance:
• Field Test: Benthic Macroinvertebrate Assemblages--
Overview: Apparent depressions in the abundances of indigenous
benthic infauna are in situ assessments of chronic and acute effects
of contaminated sediments. These tests generally involve the collection
of sediment samples using a bottom grab or box corer and the sieving of
the samples through a screen having a mesh size of 1.0 mm. The
organisms retained on the screen are collected, preserved using
formalin, and later identified and counted in the laboratory. The
kinds of species and numbers of individuals present at each station are
then evaluated to determine whether the overall benthic assemblage
appears to be altered. At each station, four to five replicate field
samples are generally collected and analyzed.
Ecological Relevance; The ecological relevance of alterations of
benthic macroinvertebrate assemblages generally is high. Because these
organisms live in close contact with bottom sediments and are relatively
stationary, they have one of the highest potentials for exposure to
sediment contaminants in marine and estuarine ecosystems. In addition,
benthic assemblages typically include organisms that are very sensitive
to chemical toxicity (e.g., amphipods). The high exposure potential and
inclusion of sensitive species make benthic organisms an excellent
indicator group. If sediment-associated adverse effects are not
detected in these organisms, then it is unlikely that they are present
in most other components of the ecosystem. The evaluation of major
taxonomic groups of benthic infauna (e.g., Crustacea, Mollusca,
Polychaeta) has been used to provide in situ measurements of chronic
and/or acute biological effects in sediments by making statistical
comparisons to reference areas in Puget Sound.
• Bioassay—Amphipod Mortality Test (Rhepoxvnius abronius)
Overview: The amphipod mortality bioassay is an indicator of
acute lethal toxicity in whole sediments. This bioassay involves a
lOrday exposure of adult organisms to a 2-cm layer of bedded (i.e,
settled) test sediment (Swartz et al. 1985, 1988). For each field
sample, 20 organisms are tested in each test chamber. The primary
endpoint is mortality.
Ecological Relevance; The test species, Rhepoxvnius abronius. is
a resident of Puget Sound and represents a group that forms an important
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component of the diet of numerous juvenile and adult fishes (Simenstad
et al. 1979; Wingert et al. 1979). As an amphipod, it is a member of a
pollution-sensitive group (Bellan-Santini 1980), although the adult
life stage typically used in sediment bioassays probably is not the
most sensitive stage in the organism's life cycle. The potential for
exposure of the test organisms to sediment contaminants is high because
they burrow into the sediment and feed upon material found naturally in
the sediment. The primary endpoint (i.e., mortality) has relatively
clear ecological meaning. That is, if adult organisms cannot survive
in an environment, it is likely that severe alterations of benthic
assemblages will be found.
• Bioassay—Oyster Larvae Abnormality Test (Crassostrea giqas)
Overview; The oyster larvae abnormality bioassay is an indicator
of acute sublethal toxicity in sediments elutriates. This bioassay
involves a 48-h exposure of embryos (2 h after fertilization) to 15 g
of bedded test sediment [Chapman and Morgan 1983; American Society for
Testing and Materials (ASTM) 1985]. For each field sample,
20,000-40,000 developing embryos are tested in each of five test
chambers. The primary endpoint is larval abnormality or failure to
develop to the fully shelled stage.
Ecological Relevance; The test species is a resident of Puget
Sound, although it was originally introduced from Japan (Kozloff 1983).
As a bivalve, it represents a group of organisms that supports
commercial and recreational fisheries in Puget Sound (i.e., clams,
mussels, oysters, and scallops) (PSWQA 1988). The life stages
evaluated (embryo and larva) represent two of the most sensitive stages
in the life cycle of the organism. The potential for exposure of the
test organisms to sediment contaminants is moderate because although
bedded sediments are present in each test chamber, bivalve embryos and
larvae reside primarily in the water column and therefore rarely are in
direct contact with bedded sediments. The primary endpoint (i.e.,
abnormality) has a relatively clear ecological meaning for the test
species and other species that rely primarily on larval recruitment to
colonize areas (i.e., species with relatively sedentary juvenile and
adult stages). That is, abnormal larvae are unlikely to survive and the
establishment of adult assemblages would thereby by prevented. The
ecological relevance of the test for motile organisms that can colonize
a contaminated area in the juvenile and adult stages is less certain,
because successful embryonic and larval development could occur in
areas removed from contamination.
• Bioassay—Microtox Saline Extract (Photobacterium phosphoreum)
Overview; The Microtox (or bacterial luminescence) bioassay is an
indicator of acute sublethal effects in sediment elutriates. This
bioassay involves a 15-min exposure of bacteria to a 500-uL aliquot of
saline extract from 13-26 g of test sediment (Bulich et al. 1981;
Beckman Instruments 1982; Williams et al. 1986). For each field
sample, a series of four dilutions is evaluated. Two replicate
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measurements are made for each dilution. Bioluminescence is measured
using an automated toxicity analyzer system with a temperature-regulated
photometer equipped with a photomultiplier. The primary endpoint,
decrease in luminescence, represents an indication of change in
cellular metabolic function (Hastings and Nealson 1977).
Ecological Relevance: The test species is a member of the
estuarine and marine pelagic communities (Holt 1977). As a bacterium,
it is representative of the group of organisms that forms the base of
detrital-based food webs (Steele 1974). That is, bacteria play a major
role in decomposing organic matter (i.e., detritus) and making it
available to higher organisms (e.g., benthic macroinvertebrates). The
potential for exposure of the test organisms to sediment contaminants
is limited by the fact that the bioassay is conducted on a saline
extract of the test sediment (i.e., sediment is not present in the test
chamber). The saline extraction will tend to remove only water-soluble
contaminants from the test sediment and therefore may not be represen-
tative of the full range of contaminants to which the organisms would
be exposed if they were in direct contact with the test sediment.
Although this test appears to be very sensitive to the influence of
chemical contaminants, it is unknown whether changes in metabolic
function have serious consequences for the organisms, or for the
ecological role of the bacteria. However, if this ecological role is
impeded, it could deprive certain higher organisms of their primary
food source and thereby alter the ability of these higher organisms to
survive.
Three other AET were also developed for the Commencement Bay N/T RI/FS.
They include a bioaccumulation AET for evaluation of PCB contamination in
relation to public health risk (Section 2.2.3) and two AET based on
additional biological indicators: depressions in abundances of six
individual benthic species, and fish histopathology.
Species-level benthic AET were found to be of similar magnitude to
higher-taxa benthic AET even though they were based on considerably less
data. For the purposes of this FS, the higher-taxa AET are preferred over
species-level AET for two reasons: 1) they are currently supported by a much
larger Puget Sound database than species-level AET, and 2) they represent a
more broadly based measure of benthic effects than do the six available spe-
cies-level AET. Because of limitations in available data, the species-level
AET were not used in developing cleanup goals for the FS.
Although fish histopathology AET were developed, they were not
considered appropriate for establishing cleanup goals in the Commencement
Bay N/T area for the following three reasons: 1) the available volume of
data were relatively limited, 2) the relationship between sediment contamin-
ation and fish exposure was uncertain because fish were not limited to
confined exposure to specific sediments, and 3) the relationship between the
chemicals of concern and the liver lesions was uncertain. Fish histo-
pathology AET may be worthy of further investigation as more data become
available.
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Summary Considerations—Taken as a whole, the AET approach provides a
powerful predictive tool for characterizing sediment quality at the
Commencement Bay N/T site. The AET approach and the AET values generated
from available Puget Sound data present advantages and limitations in their
application to the development of cleanup goals and remedial strategies.
The AET approach and existing AET offer the following advantages:
• Applicability to a wide range of chemicals (allowing for
application to a variety of sources present on the site)
• Applicability.to a wide range of biological effects indicators
(allowing for protection against a wide range of environmental
impacts)
• Reliance on objective statistical criteria to determine
adverse biological effects relative to Puget Sound reference
conditions (which enhances the technical defensibility of
AET over approaches that rely on professional judgment to
determine impacts)
• Supported by noncontradictory evidence of adverse biological
effects above the AET for a database comprising over 300
samples (including 287 amphipod bioassay stations, 201
benthic infauna stations, 56 oyster larvae bioassay stations,
and 50 Microtox bioassay stations)
• Extensive validation with field-collected sediment samples
(Tetra Tech 1986a; PTI 1988c), including 50-60 samples from
the Commencement Bay N/T RI
• Consistency with methods and approaches being used by other
Puget Sound sediment management programs.
The AET approach and the existing AET database also have the following
limitations or sources of uncertainty:
• Extensive data requirements (not a major disadvantage for the
Commencement Bay N/T RI/FS because AET have already been
developed in Puget Sound)
• Not supported by definitive cause-and-effect data (only the
spiked sediment bioassay approach is based on such data)
• AET have not been generated for a definitive indicator of
chronic effects (although benthic infauna AET may represent
chronic effects to some extent)
• Uncertainty can be increased by certain factors in field-
collected samples, most notably, interactive effects,
unmeasured toxic chemicals, and geochemical matrix effects
(discussed previously)
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• Uncertainty related to the probability of statistical
classification error (alpha or beta) (Tetra Tech 1986a; PTI
1988c)
• Uncertainty related to data distributions (in particular, the
magnitude of concentration gaps between the station setting
an AET and the adjacent impacted and nonimpacted stations)
(Tetra Tech 1986a).
Although the above sources of uncertainty are of concern, detailed validation
tests of AET with field-collected data (Tetra Tech 1986a; PTI 1988c)
indicate that the approach is relatively reliable in predicting biological
effects despite these potential uncertainties and confounding factors.
Based on validation tests with the existing Puget Sound database of over 300
samples, AET were from 86 to 96 percent reliable in predicting adverse
effects when they did occur and in not predicting effects when none were
observed (PTI 1988c).
Although the AET has shown a relatively high degree of reliability, it
must be recognized that the database will continue to be refined over time
as new information is made available. Thus, sediment management decision-
making process at the site includes an opportunity to evaluate the validity
of predicted effects by allowing, and in some cases requiring, direct
biological testing of field samples. These administrative considerations
are discussed in more detail in Sections 2.2.4 and 2.2.5.
2.2.3 Evaluation of Human Health Effects
Human exposure to contaminants in Commencement Bay sediments is
possible via a number of pathways. The pathway of greatest concern is the
ingestion of fish or shellfish contaminated by chemicals from the water or
sediments. Other potential exposure pathways include dermal absorption or
ingestion of chemicals as a result of direct contact with sediments,
ingestion or dermal absorption of contaminants in the water, and inhalation
of contaminants that volatilize from sediments or water.
Health risk assessments are designed to evaluate the nature, magnitude,
and probability of adverse impacts to human health resulting from these
types of exposure. The risk assessment process can be divided into four
major steps:
• Hazard identification
• Exposure assessment
• Dose-response assessment (often combined with hazard identifi-
cation)
• Risk characterization.
A baseline assessment of risks associated with the consumption of seafood
from Commencement Bay was performed as part of the remedial investigation
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(Versar 1985). The baseline evaluation is a risk assessment of the current
conditions and, as such, represents an evaluation of the "no action"
alternative. The results of this assessment are summarized in Sec-
tion 2.2.3.
The Versar (1985) report is limited to an evaluation of the health
risks associated with observed levels of contamination in fish tissue.
During the FS, two approaches for extrapolating from contaminant concentra-
tions in sediments to contaminant concentrations in fish tissue (and health
risks) were evaluated, as described in Section 2.2.3. These two approaches
can be used to estimate the level of risk reduction associated with various
proposed cleanup levels. Overall health risk conclusions are presented in
Section 2.2.3.
Baseline Public Health Assessment—
The public health assessment prepared by Versar (1985) was designed to
determine if there were significant health risks associated with the
consumption of contaminated seafood from the study area. This assessment
considered three types of exposure: consumption of fish muscle tissue,
consumption of fish livers, and consumption of crab muscle tissue.
Assessment methods, major study findings, and general conclusions are
summarized below.
Method—The risk assessment procedures used by Versar (1985) were
divided into three main tasks: exposure assessment, hazard assessment
(including hazard identification and dose-response assessment), and risk
characterization.
Exposure Assessment—The first step in the exposure evaluation was to
estimate the size of the exposed population (i.e., individuals consuming
fish or shellfish from Commencement Bay). Based on the results of a survey
conducted by the Tacoma-Pierce County Health Department (Pierce et al.
1981), it was estimated that there are 4,070 shore and boat anglers in the
Commencement Bay area. Assuming an average family size of 3.74 persons, an
estimated 15,200 persons consume fish or shellfish from Commencement Bay.
The second step in the exposure evaluation was to calculate the
quantity of fish consumed by the exposed population. Information in the
Tacoma-Pierce County Health Department catch-consumption survey was used to
estimate the frequency of fishing. That value was multiplied by the average
catch per trip of nonsalmonid fish intended for consumption. These
calculations indicate that a small proportion of the exposed population
(i.e., 30 of 15,220 or 0.2 percent) consumes fish at the highest estimated
rate of 1 Ib/day (454 g/day). These calculations also indicate that 82
percent of the exposed population consumes less than 1 Ib/mo (15 g/day) and
that more than half the population (57 percent) consumes Commencement Bay
fish at the lowest rate of 1 Ib/yr (1.2 g/day). Consumption of crabs was
assumed to follow a similar distribution.
Consumption of fish livers was considered a potential problem for a
small portion of the exposed population. However, no data were available on
' 2-33
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consumption rates. Therefore, it was assumed that all persons who eat fish
livers eat them from all the fish they catch. It was also assumed that the
liver mass was proportional to the liver-to-muscle ratio (12 percent) of
Commencement Bay fishes. Therefore, at the maximum estimated fish consump-
tion rate of 1 Ib/day, the corresponding maximum liver consumption rate
would be 0.12 Ib/day.
The final step in the exposure evaluation was to multiply the estimated
seafood consumption rates by the concentrations of contaminants in fish and
crab tissue, and divide this product by an assumed value for human body
weight. Tissue contaminant data for English sole fParoohrvs vetulus)
collected as part of the RI (Tetra Tech 1985a) were used for that analysis.
English sole was used as an indicator species for potential human exposure to
contaminants in nonsalmonid fishes for three reasons:
• They are more bioaccumulative than other species
• They are seasonal residents in areas where they are caught
• They may be representative of contaminant bioaccumulation
associated with the sediment environment at specific
locations in Commencement Bay.
Hazard Assessment—The dose-response variables for each contaminant were
reviewed in this stage of the risk assessment. A generalized illustration
of the role of these variables in dose-response relationships for carcinogens
and noncarcinogens is shown in Figure 2-7. The carcinogenic potency factor
[expressed in units of (mg/kg/day)"*] is typically determined by the upper
95 percent confidence limit of slope of the linearized multistage model
which expresses excess cancer risk as a function of dose. The model is
based on high to low dose extrapolation, and also assumes that there is no
threshold for the initiation of toxic effects. The reference dose (RfD,
expressed in units of mg/kg/day) is an estimated single daily chemical
intake rate that appears to be without risk if ingested over a lifetime. It
is usually based on the relationship between the dose of a noncarcinogen,
and the frequency of systemic toxic effects in experimental animals or
humans. It also assumes that a threshold exists for the initiation of toxic
effects. The threshold of observed effects is divided by an uncertainty
factor to derive an RfD that is protective of the most sensitive members of
the population. The general source for this information was the supporting
literature for standards and criteria, carcinogenic potency factors, and
RfD values.
Risk Characterization—Risk characterization is the process of
estimating the magnitude of potential adverse health effects under various
conditions defined in the exposure assessment. The risk characterization
integrates the information developed during the exposure and hazard
assessment to yield a characterization of potential health effects.
Potential risks associated with each carcinogenic chemical of concern in
various exposure media were estimated as the probability of excess cancer
using the equation:
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V)
CC
o
o
UJ
O
UJ
IT
U.
LOW-DOSE
REGION OF
CONCERN
SLOPE - POTENCY FACTOR
DOSE OF CARCINOGEN
LEGEND
OBSERVED DATA POINTS
% Chemical A
| Chemical B
MODELS
— — — Low Dose Extrapolation
^__ Models Fit Within
Observed Data Range
O
i
UJ
31-
a
UJ
oc
RfD
UF
Reference Dose
Uncertainty Factor
N O A E L No Observed Adverse
Effects Level
DOSE OF NONCARCINOGEN
Figure 2-7. Hypothetical dose-response relationships for a
carcinogen and a noncarcinogen.
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Rii = 1 - exp(-Pi
where:
RJJ = Risk associated with chemical i in medium j
Pi = Carcinogenic potency factor for chemical i (mg/kg/day)"1
D-JJ = Dose of chemical i in medium j (mg/kg/day).
Attributes of carcinogenic potency factors and methods of dose estimation
are as described above. Nonprobabilistic hazards associated with ingestion
of noncarcinogenic chemicals were expressed as a ratio:
where:
= Risk index for chemical i in medium j
= Dose of chemical i in medium j (mg/kg/day)
= Reference dose for chemical i (mg/kg/day)
Characteristics
above.
of the RfD and methods of dose estimation are described
Results of Public Health Assessment--
Fish Consumption—At the maximum consumption rate of 1 Ib/day
(454 g/day) of nonsalmonid fish from Commencement Bay, the estimated
individual lifetime cancer risks exceed 1 in 1 million for six carcinogens:
PCBs, arsenic, hexachlorobenzene, hexachlorobutadiene, bis(2-ethyl-
hexyl)phthalate, and tetrachloroethene. At a fish consumption rate of 1
Ib/mo (15 g/day), only PCBs and arsenic would exceed the 1 in 1 million
risk level. For a given consumption rate, estimated individual risks from
consuming Commencement Bay fish muscle tissue exceed those for consuming
Carr Inlet (reference area) fish for three of the above six compounds:
PCBs, bis(2-ethylhexyl)phthalate, and tetrachloroethene. For PCBs,
individual risks from consuming Commencement Bay fish are about 5 times as
high as the risks associated with consuming Carr Inlet fish. For arsenic,
estimated individual risks from consuming Commencement Bay fish and Carr
Inlet fish are similar.
Fish tissue concentrations and the associated risk for consuming
nonsalmonid fish varied among the Commencement Bay waterways. Fish consumed
from City and Hylebos Waterways represent the greatest individual risk from
PCB contamination. Risk associated with consumption of those fish was 10
times as high as that associated with fish from Carr Inlet.
Much of the shore fishing in Commencement Bay occurs on piers along the
Ruston-Pt. Defiance Shoreline. Therefore, contamination of fish in this
area is of special concern relative to possible public health impacts. The
available data indicate that individual risks for all chemicals in the Pt.
Defiance area are similar to those in the Carr Inlet reference area.
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Antimony., lead, and mercury were present in fish muscle tissue at
levels that would cause exposure to exceed the RfD values at the 1 Ib/day
consumption rate. Tissue concentrations of these chemicals were very similar
among project areas and at the Carr Inlet reference site. At the lower
consumption rate of 1 Ib/mo, however, estimated exposure does not exceed the
RfD values.
Twenty-one chemicals were detected in a nonsalmonid fish liver
composite sample from Commencement Bay, Four of the detected chemicals are
carcinogens: PCBs, hexachlorobenzene, hexachlorobutadiene, and arsenic. At
the maximum consumption rate of 0.12 Ib/day (56 g/day), consumption of PCBs
in fish liver would result in a predicted individual lifetime risk of
2 in 100. This risk is higher than the corresponding risk associated with
consumption of PCBs in fish muscle tissue (6 in 1,000) because of the much
higher PCB concentrations in fish livers. The predicted risk level for PCBs
in Commencement Bay fish livers is about 15 times as high as the correspond-
ing risk for fish livers from Carr Inlet.
Maximum estimated carcinogenic risks for hexachlorobenzene and
hexachlorobutadiene in fish liver were about the same as the corresponding
risks for fish muscle (i.e., 1 in 10,000 and 1 in 100,000). All other
estimated carcinogenic risks were much lower than these levels.
All calculated exposures for the noncarcinogens present in fish livers
from Commencement Bay were less than 10 percent of the corresponding average
daily intakes (ADIs). Therefore, even at the maximum consumption rate of
0.12 Ib/day, no human health effects attributable to these noncarcinogens
would be expected.
Of the chemicals detected in fish livers from Commencement Bay, PCBs
pose the greatest potential risk to public health. Although the maximum
estimated risk of 2 in 100 is associated with a high consumption rate, much
less frequent consumption of fish livers would still result in a substantial
predicted risk.
Crab Consumption—A risk assessment was also conducted for consumption
of crabs harvested in Commencement Bay. For PCBs and arsenic, the estimated
individual risks from eating crabs only were approximately the same as those
for eating fish. Risk associated with consumption of PCB-contaminated crabs
from Commencement Bay were 3 times as great as those associated with crabs
from Carr Inlet.
Calculated exposures from consumption of crab muscle at the maximum
rate of 1 Ib/day (454 g/day) exceeded the ADI for the following contaminants:
antimony, lead, silver, zinc, and mercury. ADIs were exceeded for crabs
from both Commencement Bay and Carr Inlet for these metals. For most of the
metals, the risk difference between Commencement Bay and Carr Inlet was
slight. By limiting consumption of crabs from either Commencement Bay or
Carr Inlet to 1 Ib/wk (65 g/day), all noncarcinogenic exposures would be
below the ADI.
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Relationship Between Sediment Contamination and Health Risks Associated With
Consumption of Contaminated Fish--
Fish in the Commencement Bay area come into contact with the sediments,
and bioaccumulation of contaminants occurs to varying degrees. To evaluate
the risk reductions associated with various remedial alternatives, contam-
inant concentrations in sediments must be extrapolated to concentrations in
edible tissues of fish and shellfish. The following two approaches were
used to evaluate this relationship:
• Apparent effects threshold approach
• Equilibrium partitioning approach.
Bioaccumulation Apparent Effects Threshold—The AET approach establishes
sediment quality values empirically by determining the sediment concentra-
tions of specific contaminants above which statistically significant
(P<0.05) elevations of contaminant concentrations in fish tissue relative to
a reference level of the contaminant are expected. (A detailed discussion
of the AET approach is described in Section 2.2.2). The advantages of this
approach are twofold: it is potentially applicable to a wide range of
contaminants, and the emphasis is on empirical field data rather than
theoretical predictions. Disadvantages include the large data requirements,
the' need to assume that fish are exposed to sediments within a known,
specified area, and the related assumption that increasing sediment
concentrations correspond to increasing tissue concentrations in field-
collected fish.
Method—More than 70 contaminants were detected in fish and crab tissue
during the RI (Tetra Tech 1985a). Bioaccumulation AET values were developed
for contaminants that satisfied the following criteria:
• Estimated health risks associated with long-term consumption
of seafood caught in Commencement Bay at a rate of 1 Ib/mo
(15 g/day) exceeded a cancer risk level of 10~° or the ADI
• Observed tissue concentrations exceeded tissue concentrations
from fish caught from Puget Sound reference areas (i.e., Carr
Inlet).
Of the 70 contaminants, observed concentrations of PCBs and arsenic
were associated with lifetime cancer risks of 10~° or greater at a consump-
tion rate of 1 Ib/mo. Because mean concentrations of arsenic in English
sole muscle tissue were greater in Carr Inlet than in all Commencement Bay
transects, it was considered inappropriate to establish an AET for arsenic
bioaccumulation. Therefore, only PCB data were used to establish a
bioaccumulation AET.
Significant bioaccumulation was determined by statistically comparing
pollutant concentrations in each Commencement Bay transect to concentrations
in Carr Inlet (i.e., reference area) transects. PCBs in English sole muscle
and sediments from 12 fish trawl transects in the Commencement Bay waterways
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(Tetra Tech 1985a) were used to generate bioaccumulation AET values for
PCBs. Fish trawl transects along open shorelines (i.e., Ruston Shoreline)
were not included in AET generation, because associations between sediment
and fish contaminant concentrations were assumed to be stronger for fish
collected in waterways. It was assumed that fish in waterways experienced a
more confined exposure to local sediment contamination than fish that were
collected along an open shoreline.
English sole muscle tissue data were evaluated for statistically
significant PCB bioaccumulation using the following steps:
/
• PCB bioaccumulation data were evaluated for normality with
the Kolmogorov-Smirnov (K-S) test (Sokal and Rohlf 1981; SPSS
1986). The data were not normally distributed (P<0.05), but
instead appeared to have a log-normal distribution.
• PCB bioaccumulation data were loglO-transformed and re-
evaluated for normality with the K-S test. The transformed
data were normally distributed (P<0.05).
• The mean and standard deviation of the loglO-transformed data
from each trawl were calculated.
• Results from each potentially impacted trawl were statis-
tically compared with Carr Inlet conditions using pairwise
analysis.
• An F-max test was used to test for homogeneity of variances
between each pair of mean values.
• If variances were homogeneous, then a t-test was used to
compare the two means.
• If variances were not homogeneous, then an approximate t-test
was used to compare means.
• Error rates for significance were adjusted for multiple
comparisons using Bonferroni's technique (Miller 1981). An
error rate of 0.004 (i.e., 0.05 divided by 12) was used for
each pairwise comparison.
Results—The bioaccumulation AET for PCBs was 140 ug/kg dry weight
sediment. However, due to the large uncertainty associated with using AET
values on a non-site-specific basis and because of limited volume of
available data with which to apply the AET approach, the bioaccumulation AET
was not used as the sole basis for establishing a sediment cleanup goal for
PCBs. However, it is useful for indicating a potential level of concern.
Equilibrium Partitioning--In the equilibrium partitioning (sediment-
biota) approach, the sediment concentrations associated with a selected
human health guideline for edible fish tissue are calculated by assuming that
chemical concentrations in sediment, interstitial water, surface water, and
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fish are in thermodynamic equilibrium (Battelle 1985a). Acceptable fish
tissue concentrations are based on existing regulatory limits (e.g., U.S.
FDA action limits or tolerances), site-specific risk calculations, or
background (reference area) concentrations. The sediment contaminant levels
that would correspond to these body burdens under thermodynamic equilibrium
are established as the sediment quality values.
This approach has been investigated by the U.S. EPA/Environmental
Research Laboratory-Narragansett, the U.S. Army Corps of Engineers, and
Battelle (1985 and 1988) as a tool for estimating bioaccumulation potential.
The advantages of this approach are that 1) it has a well-developed
theoretical basis, 2) it utilizes available toxicological databases, and
3) it applies to a wide variety of sediment types (i.e., a wide range of
organic carbon content). Disadvantages are that 1) it is limited to
nonpolar, nonionic organic compounds, 2) it assumes multiphase equilibrium,
and 3) it assumes that individuals are exposed to sediments within a known,
specified area.
The equilibrium relationship used to establish sediment quality values
is based on:
Kibs = cib/cis
where:
Kibs = Partition coefficient between biota and sediment for chemical i
C-jb = Lipid normalized concentration of chemical i in biota (mg chemi-
cal/kg lipid)
Cis = Organic carbon normalized concentration of chemical i in sedi-
ments (mg chemical/kg organic carbon).
There are a number of assumptions inherent in the use of this approach:
1) Thermodynamic equilibrium exists among sediment, fish/shell-
fish, and interstitial water.
2) Hydrophobic pollutants associate predominantly with lipids in
all aquatic organisms, and the affinity of lipids for these
pollutants is equivalent for all organisms; similarly,
hydrophobic pollutants associate predominantly with organic
carbon in all sediments and the affinity of organic carbon
for these pollutants is equivalent in all sediments.
3) The equilibrium distribution of hydrophobic organic pollutants
between lipids and sedimentary organic carbon (i.e., the
partitioning coefficient) is constant regardless of the type
of organism or sediment and regardless of the specific
compound.
2-40
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Method—Sediment quality values for PCBs were established using a five-
step approach. Each step of the procedure is discussed below.
Step 1. Determine Acceptable Fish Tissue Concentrations—There are
three primary approaches available for defining acceptable concentrations of
contaminants in fish tissue: promulgated regulations or guidelines,
background (reference) concentrations, and risk assessments.
• Regulations/Guidelines: The FDA has stated that levels of
"no effect" or "allowable daily intake" cannot be established
for PCBs and therefore any potential exposures should be
reduced as low as possible. The FDA tolerance level for PCBs
in fish and shellfish is 2 mg/kg. This tolerance level is
applicable only to fish shipped in interstate commerce.
• Puget Sound Background Concentrations: The 2 mg/kg tolerance
level is substantially higher than the PCB concentrations
found in fish tissue from nonindustrial areas of Puget Sound.
"Background" levels in fish tissue range from 7 to 70 ug/kg
wet weight (Tetra Tech 1986a). The average PCB concentration
in Carr Inlet fish tissue was 36 ug/kg wet weight (Tetra Tech
1985a).
• Cancer Risk Levels: Fish tissue guidelines can also be
developed using standard risk assessment data and methods.
Tetra Tech (1988) has developed a graphical method for
characterizing health risks associated with a wide range of
chemical concentrations and consumption rates for a variety
of seafoods. For example, at a fish consumption rate of
12.3 g/day, a PCB concentration of 100 ug/kg (wet weight) is
associated with an excess lifetime cancer risk of approxi-
mately 10'4 (Figure 2-8).
For purposes of the FS evaluation, the mean Carr Inlet tissue concen-
tration (36 ug/kg) was selected as the guideline tissue concentration. This
level corresponds to an excess lifetime cancer risk of approximately
4 x 10"5. This is within the range of risks (10~4 to 10"') generally
considered acceptable in Superfund cleanups. Potential guideline concentra-
tions for PCBs in fish tissue are summarized in Table 2-2.
Step 2. Determine Sediment and Fish Characteristics—Two key environ-
mental factors and characteristics of fish and sediments that affect the
equilibrium partitioning between sediment, water, and fish are sediment
organic carbon content and fish lipid concentration. The organic content of
the sediments is one of the most important environmental variables in
predicting partitioning of organics such as PCBs between sediments and the
water column. In Commencement Bay, average organic carbon content varies
from 1.4 percent in Blair Waterway to 6.2 percent in Middle Waterway. Carr
Inlet sediments contain an average organic carbon content of 0.3 percent
(Tetra Tech 1985a).
2-41
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->
r\>
CONSUMPTION RATE (g/day)
1000 100 10 1 0.1 0.01 0.001
/
I I f I I I
0.000001 0.00001 0.0001 0.001 0.01 0.1
I I I
1 10 100
I I I
1000 10.000 100,000
CONCENTRATION (mg/kg wet weight)*
* 1 mg/kg wet weight = 1 ppm
a Four tablespoons per day
b 100 steaks per year
c 2 L per day at the U.S. EPA limit (0.005 mg/L)
PEANUT BUTTER
(AFLATOXIN B) a
CHARCOAL BROILED STEAK
(BENZO(A)PYRENE] b
DRINKING WATER
(TRICHLOROETHYLENE) c
Figure 2-8. Graphical risk characterization for PCBs in seafood.
-------
TABLE 2-2. POTENTIAL GUIDELINE CONCENTRATIONS FOR PCBs IN
FISH TISSUE, COMMENCEMENT BAY N/T FEASIBILITY STUDY
Concentration
Description (ug/kg)
U.S. FDA tolerance 2,000
10'4 risk level3 81
Background (Carr Inlet) 36
10"5 risk level 8
10'6 risk level 0.8
a Risk calculations were based on the following assumptions:
Carcinogenic potency factor = 7 (ug/kg/day)"^
Ingestion rate = 12.3 x 10'3 kg fish/day
Human body weight = 70 kg.
2-43
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Neutral compounds such as PCBs are distributed primarily in the lipids
of exposed organisms. A correlation between the lipid concentration and the
steady-state PCB concentration in the various tissue types has been shown by
several researchers. Because muscle tissue contains the lowest lipid
concentration, it can be expected to have lower PCB concentrations than the
other tissue types. In Commencement Bay, lipid concentrations in fish
muscle tissue ranged from 2.1 to 3.1 percent (mean = 2.6 percent) (Tetra
Tech 1985a).
Step 3. Define Equilibrium Relationships—There are several available
methods for predicting the partitioning of neutral chemicals between
sediment and fish. The equilibrium equation used in this evaluation was
developed by the U.S. Army Corps of Engineers (1987) Waterways Experiment
Station to predict the maximum bioaccumulation potential that could occur
from a given sediment contaminant level. The equation is as follows:
Ct = 1.72 x (Cs/fOC) x fl_
where:
Ct = Predicted fish tissue concentration (ug/kg wet weight)
Cs = Sediment contamination level (ug/kg dry weight)
fOC = Decimal fraction of the sediment organic carbon content (%)
fL = Decimal fraction of an organism's lipid content (%)
In essence, this equation states that the ratio of lipid-normalized
tissue concentration to organic carbon-normalized sediment concentration is
constant (i.e., 1.72). In order to check the utility of this method for the
Commencement Bay area, the above equation was used to predict the fish
tissue concentrations in each of the waterways. This predicted value was
then compared with the observed values. As shown in Table 2-3, the
predicted values ranged from 12 to 250 percent of the observed values.
Step 4. Calculate Range of Sediment Quality Values—Using the
equilibrium relationships developed by the U.S. Army Corps of Engineers, a
range of sediment quality values were calculated. These sediment quality
values represent sediment concentrations predicted to be in equilibrium with
background (Carr Inlet) fish tissue concentrations (36 ug/kg wet weight).
Sediment quality values were calculated for each waterway and the Ruston-
Pt. Defiance Shoreline based on the average sediment organic carbon content
for that particular area. An average fish lipid concentration of 2.6 percent
was used for all areas. Sediment quality values that are expected to result
in background PCB concentrations in fish from each waterway are identified
in Table 2-4.
Step 5. Determine Sediment Cleanup Goals—In order to evaluate various
sediment cleanup levels, sediment PCB concentrations representative of a
range of potential post-cleanup conditions were derived and used to
estimate long-term health risks associated with the consumption of PCB-
contaminated seafood. The method used to derive post-cleanup conditions was
based on considerations of available remedial technologies and potential
sediment action levels.
2-44
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TABLE 2-3. PREDICTED VS. OBSERVED PCB CONCENTRATIONS
IN FISH TISSUE FROM COMMENCEMENT BAY
Location
Hylebos Waterway
Blair Waterway
Sitcum Waterway
Milwaukee Waterway
St. Paul Waterway
Middle Waterway
City Waterway
Ruston-Pt. Defiance
Shoreline
Average
Predicted
PCB Concentration3
(ug/kg wet weight)
410
107
130
90
77
35
44
180
134
Observed
PCB Concentration1*
(ug/kg wet weight)
332
253
172
100
40
170
354
68
186
Predicted/
Observed
(%)
123
42
76
90
193
21
12
265
72
a Based on methods in U.S. Army Corps of Engineers (1987) and McFarland
(1984).
b From Tetra Tech (1985a).
2-45
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TABLE 2-4. SEDIMENT QUALITY VALUES THAT ARE EXPECTED TO RESULT IN
BACKGROUND CONCENTRATIONS OF PCBs IN FISH OF COMMENCEMENT BAY3
Concentration
Location (ug/kg dry weight)
Hylebos Waterway 30
Blair Waterway 11
Sitcum Waterway 15
Milwaukee Waterway 16
St. Paul Waterway 45
Middle Waterway 50
City Waterway 48
Ruston-Pt. Defiance 27
Shoreline
Commencement Bay 30
a Background concentration is 36 ug/kg wet weight, based on
samples of English sole from Carr Inlet (Tetra Tech 1985a).
2-46
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The primary remedial technologies considered appropriate to contaminated
sediments in the Commencement Bay area involve either removal or capping
with clean sediments. Both of these measures can be assumed to result in
essentially background conditions. Consequently, in estimating average post-
cleanup sediment concentrations, the general approach was to assume that all
sediments with concentrations greater than a potential action level are
removed and replaced by sediments with concentrations equal to Puget Sound
reference areas. For a given sediment action level, the resulting post-
cleanup concentration was assumed to be the geometric mean of sediments that
would be remediated because they exceeded the action level, and those
remaining sediments that would not be remediated because they were less than
the action level. In order to identify an acceptable post-cleanup level, a
reference concentration of 20 ug/kg dry weight was assumed, and seven
potential sediment action levels (i.e., 50, 100, 150, 200, 250, 500, and
1,000 ug/kg dry weight) were evaluated as described below.
Geometric mean values for various cleanup levels were calculated in a
systematic, iterative manner. All of the sediment concentrations within a
particular area were rank-ordered by PCB concentration. The rank order of
sediments represents the cleanup priorities for that area (i.e., sediments
with the highest observed PCB concentrations have the highest priority for
cleanup). Beginning with the maximum rank-ordered PCB concentration, a
range of possible post-cleanup concentrations was determined in the
following manner:
• First, PCB concentration of 20 ug/kg (Puget Sound reference)
was substituted for all of the observed values that exceeded
the highest potential action level of 1,000 ug/kg dry weight
• Second, an overall post-cleanup concentration was determined
by calculating a geometric mean for the entire data set using
the substituted values and the remaining unsubstituted values
• This process was repeated for each of the remaining potential
wet action levels (i.e., 50, 100, 150, 200, 250, and
500 ug/kg dry weight.
The geometric mean concentration at each step in this process represents the
average residual concentration in the entire waterway following the
removal/capping/treatment of sediments that exceeded the specified potential
action levels.
Results--Post-cleanup evaluations were performed for Hylebos Waterway,
which had the highest observed PCB levels, and for Commencement Bay as a
whole. Results of the Hylebos Waterway evaluations are summarized in
Table 2-5. The results for Commencement Bay as a whole are very similar to
those for Hylebos Waterway. Not unexpectedly, the mean post-cleanup sediment
concentrations are reduced as the stringency of the cleanup increases.
Based on available data, remediation of sediments exceeding a PCB concen-
tration of 150 ug/kg dry weight will reduce average sediment concentrations
in Hylebos Waterway to 30 ug/kg dry weight. At this sediment concentration,
2-47
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TABLE 2-5. AVERAGE SEDIMENT PCB CONCENTRATIONS
ACHIEVED WITH ALTERNATIVE CLEANUP LEVELS
Cleanup Level
(ug/kg
dry weight)
Mean
Residual
Sediment
Concentration
(ug/kg dry weight)
Mean
Predicted Fish
Concentration
(ug/kg wet weight)
Predicted Fish
Concentration
as a Percent
of Reference3
1,000
500
250
200
150
100
50
150
105
62
48
30
24
22
186
130
77
60
37
30
27
515
360
213
166
102
83
75
a Average reference concentration is 36 ug/kg wet weight based on fish in
Carr Inlet (Tetra Tech 1985a).
2-48
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the predicted PCB fish tissue concentrations (37 ug/kg wet weight) would be
essentially equivalent to those in Carr Inlet (36 ug/kg wet weight).
Similar results are expected for Commencement Bay as a whole.
Conclusions of Human Health Assessment--
The most significant human health risks from contaminated sediments in
Commencement Bay appear to be related to the elevated concentrations of PCBs
in sediment and fish tissue (Tetra Tech 1985a, Versar 1985). Sediment
concentrations range from 6 to 2,000 ug/kg dry weight, with a mean concen-
tration of 140 ug/kg. In most cases, these levels are significantly higher
than the sediment concentrations in Carr Inlet, where the average concen-
tration is 6 ug/kg dry weight. Average fish tissue concentrations vary from
waterway to waterway. The highest average values were found in fish from
City (354 ug/kg wet weight) and Hylebos Waterways (332 ug/kg wet weight).
These contamination levels are associated with excess lifetime cancer risks
of approximately 4.0 x 10 .
The AET and equilibrium partitioning approaches were used to develop
PCB sediment cleanup levels that address human health protection. The
bioaccumulation AET defines the sediment concentrations above which
statistically significant increases in fish tissue concentrations (relative
to Carr Inlet) would be predicted. The bioaccumulation AET for PCBs is
140 ug/kg dry weight.
Using the equilibrium partitioning approach, sediment concentration
levels predicted to be in equilibrium with fish tissue concentrations from
Carr Inlet were calculated. For purposes of the FS, PCB levels in Carr
Inlet fish tissue were considered to be representative of PCB levels in fish
tissue in Puget Sound reference areas. A sediment quality value of 30 ug/kg
was calculated using this approach. Remediation of sediments with concen-
trations greater than 150 ug/kg would result in average post-cleanup sediment
concentrations of approximately 30 ug/kg dry weight. Following implementa-
tion of source control measures and sediment remediation, average concentra-
tions of PCBs in surface sediments would be expected to be reduced further
by natural sedimentation and biodegradation.
Taken together, the two approaches provide a reasonable basis to
establish sediment cleanup levels. For the purpose of evaluating cleanup
alternatives in Commencement Bay, the proposed sediment cleanup level for
PCBs is 150 ug/kg dry weight. This sediment concentration is predicted to
result in fish tissue concentrations of PCBs that are similar to those in
fish from Carr Inlet.
2.2.4 Administrative Definition of the Lona-Term Goal
Achievement of the long-term goal for remediation of the nine
Commencement Bay N/T sediment problem areas requires a management plan that
utilizes the power of the AET approach while recognizing its limitations. A
two-step approach has been developed to help translate the long-term goal
from a conceptual definition into an administrative framework. It is
important to recognize that the AET database is being considered for
2-49
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application as a sediment management tool within a larger management
strateav for the site. Thus, its predictive power may help define the
extent of a particular problem area and streamline confirmatory sediment
sampling operations. However, this approach is fundamentally based on the
results of direct environmental sampling and subsequent chemical and
biological analysis that have been used to document the nine Commencement
Bay N/T problem areas described in the RI/FS. These results confirmed
significant environmental degradation in each of the problem areas, based on
a combination of chemical and biological analyses. The chemical analyses
indicated concentrations of contaminants that are hundreds to thousands of
times as great as those in reference areas. The biological testing
indicated significant impact to indigenous benthic species, bottom-feeding
fish, and shellfish. However, the spatial extent of the problem areas
requires considerable refinement, which can be effectively accomplished
through appropriate use of the AET database.
Management Approach--
The two-step management approach proposed for use at the Commencement
Bay N/T site continues to rely on a combination of chemical and biological
testing to assess sediment quality. In the first step, the long-term goals
are defined in terms of chemical-specific values derived from the AET
database. Numerical sediment quality values were established for each of
the 64 Commencement Bay N/T chemicals of concern, and existing sediment
chemical data from the site were evaluated to identify areas with chemical
concentrations that do not meet the long-term goal. This step allows the
problem areas to be defined in terms of spatial extent and volume, based on
chemistry, for the purpose of the FS. In addition, it will facilitate
future sampling required to better define each problem area prior to remedial
action, and to monitor the effectiveness of the cleanup after remedial
action. Another advantage of this approach is that sediment sampling oper-
ations based primarily on chemical analysis (related to the long-term goal)
may be more cost-effective and have a quicker return of data than biological
testing.
The second step in the Commencement Bay N/T sediment management
approach provides the flexibility to administratively define the long-term
goal in terms of chemical or biological testing. Because the AET database
is being used as a predictive tool, a degree of uncertainty is inherent in
chemical-specific sediment quality values defined by the AET approach.
Therefore, it may •• be appropriate to confirm predicted sediment toxicity
via direct biological testing in order to prevent the unnecessary remediation
of sediments within problem areas that are not accurately characterized by
the existing AET database. This is discussed in Section 2.4.
Long-Term Goals Based on Chemistry--
If the long term goal for the site is driven by a mandate requiring no
"acute or chronic adverse effects", as suggested in Section 2.2.1, then the
lowest AET value for a given chemical (LAET) may be an appropriate way to
administratively define that goal, provided all the tests are accepted as
sufficiently sensitive, reliable, and environmentally relevant.
2-50
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As part of the FS, the following three options were evaluated to define
contaminant concentrations that provide protection of human health and the
environment (described in PTI 1988c):
1) The lowest AET for a range of four biological indicators
(amphipod, oyster larvae, benthic infauna and Microtox)
2) The lowest AET for a range of three biological indicators
(amphipod, oyster larvae, and benthic infauna)
3) The lower of either the maximum AET value for three indicators
(amphipod, oyster larvae, and benthic infauna) or the lowest
severe effects AET for the same indicators. Severe effects in
biological tests are defined as >50 percent bioassay response
or benthic infaunal depressions in more than one major
taxonomic group.
In establishing a cleanup goal for PCBs, the bioaccumulation AET and
the equilibrium partitioning approach were also included among the indicators
considered. For Option 2, the EP value for PCBs (i.e., 150 ug/kg) was lower
than AET established by other biological indicators. Consequently, it was
used to define the long-term goal for PCBs. The sediment quality values
corresponding to each of the three options are provided in Table 2-6.
Option 2 was selected to define the long-term goal based on chemical -
specific sediment quality values for the Commencement Bay N/T site. The
biological indicators included in Option 2 are considered sufficiently
sensitive, reliable, and environmentally relevant to establish a cleanup
goal for the site that is protective of the environment. By including the
EP value for PCBs, Option 2 is also considered protective of human health,
and therefore consistent with CERCLA Section 121. The use of the lowest AET
for the three biological indicators (amphipod, oyster larvae, and benthic
infauna), which measure acute, and to a degree, chronic effects, is
protective of adverse biological effects in Puget Sound, and is therefore
consistent with the requirements contained in the Puget Sound Water Quality
Authority's 1989 Management Plan and Ecology's current efforts to fulfill
those requirements. By including the benthic infauna AET, Option 2 provides
some measure of protection against chronic effects in the environment. It
therefore provides the most appropriate administrative definition of the
long-term goal of the approaches currently available.
Option 1 was not selected for several reasons. First, the Microtox AET
was not considered as an appropriate component of the chemically based long-
term goals. Although there are a number of technical considerations
supporting the use of the Microtox bioassay in setting cleanup goals, several
considerations have caused agencies in a number of different programs to
limit its use as a stand-alone biological indicator of sediment toxicity.
The test is often perceived as overly sensitive when compared to tests using
higher organisms. It is also difficult to extrapolate the results of the
Microtox test to effects in marine microbial communities. Use of the
Microtox AET was also found to reduce the efficiency of defining impacted
sediments while providing only small improvements in sensitivity. Although
2-51
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TABLE 2-6. CLEANUP GOAL OPTIONS CONSIDERED FOR
COMMENCEMENT BAY N/T FEASIBILITY STUDY
(ug/kg dry weight for organics; mg/kg dry weight for metals)
Low molecular weight PAH
naphthalene
acenaphthylene
acenaphthene
fluorene
phenanthrene
anthracene
High molecular weight PAH
fluoranthene
pyrene
benz (a) anthracene
chrysene
benzofluoranthenes
benzo(a)pyrene
indeno(l,2,3-cld)pyrene
dibenzo (a, h) anthracene
benzo (g , h , i ) peryl ene
Total PCBs
Chlorinated organic compounds
1,3-dichlorobenzene
1,4-dichlorobenzene
1 , 2-di ch 1 orobenzene
1 ,2,4-trichlorobenzene
hexachlorobenzene (HCB)
Phthalates
dimethyl phthalate
diethyl phthalate
di-n-butyl phthalate
butyl benzyl phthalate
bis(2-ethylhexyl) phthalate
di-n-octyl phthalate
Pesticides
p,p'-DDE
p,p'-DDD
p.p'-DDT
Option 1
5,200a«e
2,100a.e
l,300c-d
500a'e
540afe
l,500a'e
960a'e
12,000e
l,700e
2,600e
l,300e
l,400e
3,200e
l,600a'e
600e
230a'e
670e
130e
>170a,c,d,e
110°. e
35e
31e
22C
71e
200C _,
1(400a,d,e
63e
1,3005
6,200d
9c
16C
34C
Option 2
5,200a J
2,100a.d
1,300°. d
500a
540a
l,500a
960a
17,000a
2,500a
3,300a
l,600a
2,800a
3,600a
l,600a
690a
230a
720a
150b
>170a,c,d
110C
50a«c
51d
22C
160a
200C
l,400a'd
900c'd
1,300°
6,200d
gc
16C
34C
Option 3
5,2009
2,1009
1,300°. d
5009
5409
2,3009
960a«e»9
30,0009
3,9009
4,3009
2,3009
2,8009
9,900C
3,600C
2,600C
970C
2,600C
l,500f
>170a,c,d,f,g,h
120a»d'f
63^ f
54a,c,f
230a.f
>l,400c.d'f«h
>l,200d.f.h
l,500h J
900C» d
l,300c-f
6,200C
gc,f
43d
34c,f
2-52
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TABLE 2-6. (Continued)
Phenols
phenol
2-methylphenol
4-methyl phenol
2, 4-dimethyl phenol
pentachlorophenol
Miscellaneous extractables
hexachlorobutadiene
dibenzofuran
benzyl alcohol
benzoic acid
N-nitrosodiphenylamine
Volatile organics
tetrachloroethene
ethyl benzene
total xylenes
Metals
antimony
arsenic
cadmium
copper
lead
mercury
nickel
silver
zinc
Option 1
420a
63a-d
670a'e
2ga,e
360d
llc
540a'e
57e
650a«c-e
28C
57C
10C
40C
150C
57C
5.1C
390a'e
450C
0.41e
>1401405«d
6.1d
410C
Option 3
l,200c»d'e'9.h
72c,f,h
1,2009
210c.h .
690c-f'h
270a
540a-e'9
1309
650f
130a'h
X-™ - -
37a«f
120a-f
200d.f u
700a'e«h
9.6a«e«h
l,300d.(!
660a.d
2.ic,d,h
>140c'd'f«h
6.1d
l,600a'e'f-9.n
a Oyster larvae bioassay AET.
b English sole muscle tissue bioaccumulation AET.
c Benthic infauna (higher taxa) AET.
d Amphipod bioassay AET.
e Microtox bioluminescence.
^ Severe benthic infauna AET.
9 Severe oyster larvae bioassay AET.
h Severe Amphipod bioassay AET.
i The criteria shown are set by the crustal abundance of nickel (based on
Turekian and Wedepohl 1961). The AET values for nickel were below crustal
abundance levels, and were thus considered inappropriate. Addition of data with
a wider range of nickel is needed.
J A detection limit value would be applied according to the procedure for
selecting target and alternative criteria; however, detection limit values are
not considered appropriate as a criterion.
2-53
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Microtox may be included as a component in Ecology's approach for inventory-
ing potential problem areas in the sound [Element S-8 of the Puget Sound
Water Quality Management Plan (PSWQA 1988)], it is unlikely to be included
as a factor in defining sediment remedial actions.
Option 3 was not selected because it was not considered environmentally
protective and is inconsistent with Ecology's efforts to develop Puget
Sound-wide sediment quality goals. It was used, however, to establish a
lower range of the areas and volumes of sediment requiring remediation.
These calculations are provided in Chapter 14.
For the purposes of the FS, cleanup goals and estimates of areas and
volumes not meeting those goals are based on sediment chemistry values.
During the remedial design phase, which precedes remedial actions, chemical
testing will be required and biological testing may or may not be required
to refine area and volume estimates and to verify the predictions based on
chemical AET values. Procedures for additional testing are presented in PTI
(1988a).
2.2.5 Review/Use of New Information
The technical approaches for evaluating the quality of marine sediments
have undergone rapid development during the last several years. It is
anticipated that continued research, evaluation of the various technical
approaches, and practical experience in their application may lead to future
modifications. In recognition of the evolving nature of the various
technical approaches, the Superfund process includes several provisions for
ensuring the timely incorporation of important new scientific evidence
during the cleanup phases of the project:
• Superfund Five-Year Reviews - Under SARA, U.S. EPA is
required to review remedial actions where hazardous substances
are left onsite at intervals of no less than 5 yr. These
reviews will provide the opportunity to incorporate additional
scientific information that becomes available during the
previous 5-yr interval.
• Remedial Design Testing - For each problem area, potentially
responsible parties (PRPs) will be required to perform
additional sediment sampling and analysis to refine the
estimates of the areal extent of contamination based on the
AET approach. The proposed refinement procedures are
described in Section 2.3.6 and PTI (1988a). The testing
procedures and data interpretations will incorporate new
scientific evidence as appropriate.
• Source Control Requirements - Many of the source control
measures being implemented under various water quality
programs are being implemented in a phased manner. This will
provide a great deal of flexibility to incorporate new
information on sediment quality values into future regulatory
decisions.
2-54
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2.3 USE OF THE LONG-TERM SEDIMENT CLEANUP GOAL
The long-term sediment cleanup goal defines a level of sediment contami-
nation that would be acceptable throughout Commencement Bay. As referenced
in Section 2.2.1, the long-term goal has not been modified to take into
account factors such as technical feasibility and cost. However, these and
other factors are often important considerations when translating the long-
term cleanup goals into individual requirements for sources of contami-
nation, routine navigation dredging projects, and sediment remedial actions.
In evaluating measures to correct sediment contamination problems in
Commencement Bay, the long-term sediment cleanup goal has been used as a
tool in making the following types of management decisions:
• Defining extent and relative priority of problem areas
• Defining source control needs
• Prioritizing areas for remedial action
• Identifying sediment areas requiring remediation.
These uses of the long-term goal are summarized in Sections 2.3.1-2.3.4.
Section 2.3.5 provides a definition of a reasonable sediment recovery time.
The remedial design procedures for refining estimates of sediment areas and
volumes requiring remediation are discussed in Section 2.3.6.
2.3.1 Defining the Extent of Areas of Concern
During the FS, the long-term cleanup goal was used to estimate the
extent of contamination in each problem area. This was accomplished by
first defining a set of "indicator chemicals" for each problem area.
Indicator chemicals represent a subset of all of the chemicals identified in
a particular area and were identified by first separating the problem
chemicals into groups that appeared to have a common source (or sources),
and then selecting the chemicals that were most representative of each
source group. These chemicals were selected on the basis of the following
three criteria: 1) they had the highest ratio of observed sediment
contamination to long-term cleanup goal (termed the enrichment ratio),
2) they were present at concentrations higher than the long-term goal over
the greatest area, and 3) they resist degradation.
The sediment areas of concern were estimated by mapping the enrichment
ratios for the indicator chemicals for all sampling stations in a problem
area. Boundaries for the surface area requiring remediation were drawn by
linear interpolation between sampling stations where sediment concentrations
exceeded the long-term goal and those where the sediment levels did not
exceed the goal. Depth of contamination, estimated from available sediment
profiles within the problem area, was slightly overestimated to account for
tolerances of the various dredging techniques and to be environmentally
protective. For each indicator chemical, area and depth data were used to
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calculate sediment volumes of concern. In problem areas with two or more
indicator chemicals, the separate volume estimates were integrated to obtain
a total problem area sediment volume. Maps showing the areas of concern are
included in Chapters 5-13.
The use of the long-term goal to define the extent of contamination in
a problem area should be distinguished from the process of identifying high
priority problem areas requiring remedial action evaluations. Criteria for
triggering an evaluation of sediment remedial action are described in
Section 1.3.5.
2.3.2 Defining Source Control Needs
The long-term goal was used to define acceptable levels of contamination
in ongoing discharges and to identify the need for additional source control
measures to protect sediment quality. The general approach involved the
following steps:
1) Estimating current discharge loadings for major sources
2) Estimating the percent source control required to reach the
long-term goal
3) Estimating the degree of source control achievable through
the implementation of all known, available, and reasonable
methods of treatment.
For the FS, contaminant concentrations from the three most contaminated
stations in a problem area were averaged to derive an estimate of the
current level of contamination in freshly deposited sediments. Two
assumptions were inherent in these estimates: 1) contaminants discharged by
sources are associated or become associated with particulate material that
accumulates primarily as sediments, and 2) source discharges are in steady-
state with sediment accumulation. The quantitative relationships between
long-term sediment cleanup goals and contaminant concentrations in the
effluent particulates were evaluated using a mathematical model (SEDCAM)
which incorporates site-specific and chemical-specific variables. Examples
of site-specific variables include suspended particle loadings of effluents,
sedimentation rate, and depth of the mixed layer in sediments near the
source. Examples of chemical-specific variables include particle affinity
and susceptibility to biodegradation.
Estimates on the degree of source control achievable through the use of
all known, available, and reasonable methods of treatment were based on a
general evaluation of sources, discharges, and pollution control tech-
nologies. These estimates will be refined as part of detailed engineering
and cost evaluations by owners and operators of individual facilities. In
evaluating and implementing individual source control actions, Ecology will
utilize a phased approach. First, sources will be required to install all
known, available, and reasonable methods of treatment. Source and sediment
monitoring will be performed to determine whether violations of the sediment
criteria are occurring. Based on this information, Ecology will then
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determine the need for either additional control measures or a "sediment
impact zone" (sediment dilution zone). This is consistent with the general
approach being developed by Ecology to fulfill the requirements of the Puget
Sound Water Quality Management Plan. Ecology and U.S. EPA will require that
final source control actions are consistent with the sediment remedial
action requirements specified in the Superfund Record of Decision for the
Commencement Bay N/T site.
2.3.3. Prioritizing Areas for Remedial Action
In developing the Commencement Bay N/T Integrated Action Plan (PTI
1988a), the long-term goal was one of several factors used to prioritize
sources and areas for further investigation, source control, or remedial
action. Relative rankings were based on three criteria: environmental
significance, effectiveness of source control, and status of action. For
source rankings, environmental significance for an individual source is
based on a consideration of contaminant types, magnitude and spatial extent
of sediment areas not meeting the long-term goal, and the relative contribu-
tion of each individual source to the sediment contamination. For area
rankings, environmental significance scores were based on an intercomparison
of spatial extent and persistence of sediments not meeting the long-term
goal. Spatial extent is defined as the area of surface sediments whose
contaminant concentrations exceed the long-term goal. Persistence is
defined as the relative proportion of contaminated sediments that is
expected to exceed the long-term goal 10 yr after a 70 percent source
control level is achieved.
2.3.4 Identifying Sediments Requiring Remediation
Under the proposed Commencement Bay approach, PRPs will be required to
remediate sediments in areas where contamination problems are not corrected
by source control and natural recovery, within a reasonable timeframe or
through navigational dredging. The long-term sediment cleanup goal is used
as the basis for determining when a sediment problem has been successfully
corrected.
The contaminant concentrations requiring remediation (i.e., removal,
capping, treatment) are higher than the long-term goal used to define the
areas of concern. The multipliers used to define those levels vary from
waterway to waterway and are a function of the types of sources, source
control effectiveness, waterway characteristics (e.g., sedimentation rates,
navigational dredging) and the length of time required for natural recovery.
The multipliers are chemical- and area-specific. They were calculated
using a mathematical model (SEDCAM). This model (described in Appendix A)
was used to estimate the highest level of sediment contamination that would
naturally recover within 5 yr, 10 yr, and 25 yr after the implementation of
source control measures. Natural recovery is defined to include reduction
in surface sediment concentrations due to sedimentation, diffusive loss to
overlying water, and biodegradation. Sediment concentrations that could
naturally recover were then used to estimate the sediment areas requiring
remediation.
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2.3.5 Definition of a Reasonable Sediment Recovery Time
The longer the recovery period following source control, the smaller
the area requiring remediation. The 10-yr timeframe was selected as a
"reasonable" recovery period based on the following factors:
1) Precedent - A 10-yr period is similar to legislatively
mandated timeframes under other environmental legislation.
For example, the 1972 Federal Water Pollution Control Act
stated it was a national goal to attain fishable and
swimmable waters by 1983.
2) Environmental Protection - CERCLA Section 121 requires that in
assessing remedial alternatives, the agencies must take into
account "... the potential threat to human health and the
environment associated with excavation, transportation, and
redisposal, and containment . . . ." The use of the 10-yr
recovery sediment volumes provides an optimal balance by
minimizing remediation-related adverse impacts while
protecting natural resources in Commencement Bay.
3) Monitoring Practicality - Additional monitoring will be
required to confirm modeling predictions. It is unlikely
that significant changes in contaminant concentrations would
be observed in timeframes of less than 10 yr.
4) Costs and Technical Feasibility - The. PSWQA 1987 and 1989
Management Plans direct Ecology to develop sediment remedial
action guidelines. Ecology is required to consider natural
recovery, cost, and technical feasibility in developing those
guidelines. Use of a 10-yr recovery period will enable
natural recovery of less contaminated areas, thereby reducing
volumes and associated costs.
2.3.6 Sediment Volume Refinement Process
Intensive sampling within individual problem areas was not performed as
part of the Commencement Bay N/T FS. The volume of contaminated sediments
requiring cleanup was estimated using available chemical and biological
data. Consequently, additional sampling will be required during the
remedial design/remedial action phases of the Superfund process to ensure
cost-effective and appropriate implementation of sediment remedial actions.
Data from the remedial design sampling will be used for the following
purposes:
• Refine estimates of the areal extent and depth of contami-
nation to be addressed by the remedial alternative
• Confirm predicted adverse biological impacts
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• Identify temporal changes in problem chemical concentrations
resulting from sedimentation and source control actions since
the RI/FS sampling phase. Documented changes will then be
used to refine predictions of the rate of problem area
recovery and to re-evaluate the need for the remedial
alternative
• Provide a baseline assessment to support subsequent monitoring
of the success of remedial action.
The steps in refining estimates of sediment cleanup volumes during
remedial design are shown in Figure 2-9. These steps may involve only
collection and evaluation of chemical data or a combination of chemical and
biological data. Following final determination of the cleanup volume, the
sediment remedial alternative will be implemented. Major changes in the
estimated sediment cleanup volume may require modification of the remedial
alternative.
Chemical Characterization--
Unless biological testing is included in remedial design site charac-
terization, a chemical sampling program for analysis of all identified
problem chemicals in the problem area is required. Guidance on chemical
sampling and analysis is provided in PTI (1988a). The results of this
sampling program will be used to establish the depth and area! extent of the
final cleanup volume. Long- and short-term cleanup goals serve as a basis
for the evaluation of chemical data. Long-term cleanup goals are used to
characterize the spatial extent of contaminated sediments, and short-term
cleanup goals are used to identify the volume of sediments subject to
remedial action (i.e., the cleanup volume). The cleanup volume is defined
horizontally and vertically by the location of the sample, at which
contamination consistently no longer exceeds any short-term cleanup goal for
any problem chemical in a given problem area. Short-term cleanup goals are
equivalent to the chemical concentrations in present-day sediments that will
attain the long-term cleanup goal after 10 yr of source control and natural
recovery. Long- and short-term cleanup goals for each problem area are
described in Chapters 5-13.
Biological Characterization--
Biological testing can be either optional or, in selected instances,
mandatory. A PRP has the option to conduct biological testing to refine
estimates of sediment cleanup volumes rather than accept the prediction of
biological effects based solely on chemical data. The option to appeal the
predictions of AET is provided in recognition that site-specific factors
could anomalously influence predictions of biological effects. The site-
specific results of biological tests will replace all predictions based on
chemical data. Because source control and natural recovery cannot be
incorporated into biological test results, the long-term cleanup goal (i.e.,
the biological effect represented by the lowest AET) will define the areal
extent of contamination when the biological testing option is exercised.
Remedial design results will not immediately be used to modify predictions
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Design Sampling Plan to
Refine Sediment Volume
l
Incorporate Biological Testing?
I
Yes
I
I
No
I
Design
Chemical/Biological
Sampling Program
to Refine Sediment
Cleanup Volume
TWO OPTIONS
Conduct all applicable
biological tests
Replace selected chemicals
with biological tests
Design Chemical
Sampling Program
to Refine Sediment
Cleanup Volume
ONE OPTION
- Test all priority
chemicals
Conduct Field Study
I
Reevaluate Cleanup Volume
Biological Test Results
and/or
Chemical Test Results
T
SUBJECT TO
AGENCY REVIEW
Has Sediment Volume Changed?
r
No
I
Yes
I
Reevaluate
Remedial Alternative
Implement Preferred
Remedial Alternative
Reference: PTI(1988a).
Figure 2-9. Refinement of sediment cleanup volume estimates.
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at other sites, but may be used to modify predictions in the future after
general review.
Guidance on biological sampling and analysis is provided in PTI (1988a)
for all conventional biological effects tests (i.e., amphipod mortality,
oyster larvae abnormality., benthic infauna depressions). Because the PCB
cleanup goal is developed from a human health risk assessment, standardized
biological tests do not apply. The option to appeal the PCB cleanup goal
can still be exercised by conducting laboratory tests that evaluate the PCB
content of fish exposed to contaminated sediment. Protocols for this type of
test have not yet been developed.
The option to focus on biological/bioaccumulation tests can be fully
exercised only in appealing the areal extent of the cleanup volume (and not
the cleanup depth), because benthic infauna analyses cannot be used to test
subsurface sediments. If the depth component of the cleanup volume is
appealed, bioassays must be performed in combination with chemical tests for
all priority chemicals. The results of the chemical tests must be compared
against cleanup goals established for benthic infauna analysis.
The PRP may elect to conduct some, but not all, of the biological tests
that apply to the problem area in question. As in the previous option,
benthic infauna analyses can be used only to test surface sediments.
Chemical cleanup goals are used to predict results for each biological
indicator that is not used in the testing program. The selection of
appropriate biological indicators for testing may depend on the relative
cost of biological and chemical analyses, as well as site-specific concerns
of the PRPs as to which biological predictions may be anomalous.
The strategy for selecting candidate biological tests that would be
incorporated into remedial testing for a given problem area would also
depend in the following factors:
• The problem chemical identified
• The relationship between AET for individual problem chemicals
or chemical classes (i.e., which biological effect is
associated with the lowest AET for a given chemical or
chemical class)
• The net effect of source control and natural recovery on the
relationship between short-term cleanup goals and the
biological effects represented by AET.
Alternative ways in which the short-term cleanup goals may relate to AET
[i.e., oyster (0), amphipod (A), and benthic infauna (B)] are illustrated in
Figure 2-10. The solid axis depicts differing relationships among AET
(Cases 1, 2, and 3). The AET with the lowest value is defined as the long-
term cleanup goal (e.g., B in Case 3). The dashed arrows depict how the
long-term cleanup goal may be adjusted to define the short-term cleanup
goal, depending on the degree of source control and the potential for
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c
o
U
C
o
u
in
O
CASE 1
B -
0(A)-
Test
A.O.B
Test
A.O
Test
A
CASE 2
A(0).
B -
A(0)
CASE 3
A(0)-
0(A)'
Test !
O.B.Ai
Test
O.B
Test
0
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B -
•IH PSDOA
A- Amphipod
B - Benthic Infsuna
O - Oyster Larvae
B-10y
O
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Reference: PTI (1988a).
Figure 2-10. Theoretical relationships among AET, long-term cleanup
goals, and short-term cleanup goals.
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natural recovery. The brackets indicate the types of biological tests that
would be appropriate to conduct over selected concentration ranges.
The optional biological testing program in the remedial design phase is
generally consistent with the intent of regional contaminated sediment
management programs, including PSDDA. Comparable tests and test protocols
are used, and site-specific biological information overrides predictions of
biological effects based on chemical data. Some specific differences among
regional programs in the interpretation of biological test results may exist
because of differing program goals (e.g., cleanup of nearshore sediments in
a multi-use environment vs. assessment of the suitability of potentially
contaminated material for disposal at a designated deepwater site).
Benthic infauna testing may be mandatory when any portion of the
cleanup volume is defined exclusively by benthic infauna AET (i.e., when the
benthic infauna AET is the lowest AET for one or more problem chemicals).
Benthic infauna testing is not a component of the PSDDA evaluation procedures
for dredged material. Because the PSDDA evaluation procedures do not
consider in situ benthic effects, it is theoretically possible that
sediments designated for remedial action also could be acceptable for
unconfined, open-water disposal. This situation occurs when the short-term
goal defined by the benthic infauna AET (which is modified for natural
recovery) is lower than the long-term goal defined by oyster larvae
abnormality or amphipod mortality. This is most likely to occur in problem
areas where the highest priority problem chemicals have benthic infauna
depressions as their lowest AET and where sedimentation rates are relatively
low. This possibility is illustrated as Case 3 in Figure 2-10.
Should the PRP choose to conduct biological testing, then the PRP must
use the following definitions of impacted station:
• 10-day amphipod mortality bioassay (Rhepoxvnius abronius) -
Impacted stations will be defined as stations where 1) the
test sample mortality is statistically significant (pairwise
alpha of 0.05) relative to the reference sample, and 2) the
test sample absolute mortality exceeds 25 percent. Results
will be classified as inconclusive if the standard deviation
is greater than 15 or if the statistical power of the test is
<0.6.
• Bivalve larvae abnormality bioassay (i.e., 4-day oyster
larvae or 2- to 4-day mussel larvae bioassays) - Impacted
stations will be defined as stations where 1) the test
sample absolute combined mortality/abnormality is statis-
tically significant (pairwise alpha of 0.05) relative to the
reference sample; 2) the test sample absolute, combined
mortality/abnormality is greater than 10 percent over
reference; and 3) the test sample absolute, combined
mortality/abnormality is greater than 20 percent over control.
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• Benthic infaunal abundance test (for surface sediments) -
Impacted stations will be defined as stations where 1) the
test sediment demonstrates a statistically significant effect
(pairwise alpha of 0.050) when compared to the reference
sediment sample; and 2) the test sediment demonstrates greater
than a 50 percent depression in the abundance of the major
taxa of Polychaeta, Mollusca, or Crustacea when compared to
the reference sediment sample.
• Laboratory exposure studies of PCB bioaccumulation in fish-
Because protocols to conduct these exposure studies have not
yet been developed, the criteria to define impacted stations
are unavailable.
Use of Additional Data to Define Areas of Concern--
Results of the additional chemical and biological testing will be used
to redefine areas of concern that exceed the long-term sediment quality goal
and will be evaluated using the following criteria:
• Areas of concern will be defined to include all sediments
where chemical contamination exceeds the long-term goal. The
chemical long-term goal is defined as the lowest AET
exclusive of Microtox (i.e., Option 2 in Section 2.2.4).
• Areas of concern will be defined to include all sediments
with demonstrated impacts on the benthic communities.
Impacted stations will be defined as described above.
• Areas of concern will be defined to include all sediments
with significant adverse effects in either the 10-day
amphipod mortality bioassay, or bivalve larvae abnormality
bioass-ay. Significant adverse effects will be defined as
described above.
Use of Additional Data to Define Sediment Cleanup Volumes--
Results from the additional chemical and biological testing will be
used to determine which sediments require remediation and will be evaluated
using the following interpretation criteria:
• Sediments containing chemical contamination concentrations
that exceed the long-term goal (adjusted for 10 yr recovery)
will require remediation.
• Sediments with demonstrated impacts on indigenous benthic
infauna will require remediation. Impacted stations will be
defined as described above.
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• Sediments with significant adverse effects in either of the
following laboratory bioassays: 10-day amphipod mortality
bioassay, or bivalve larvae abnormality bioassay. Significant
adverse effects will be defined as described above.
2.4 RELATIONSHIP BETWEEN THE FEASIBILITY STUDY AND EXISTING REGULATORY
PROGRAMS
Sediment contamination in the Commencement Bay N/T area is the result
of contaminant discharges from many different sources over an extended
period of time. These sources are regulated under a number of environmental
programs. Excavation, capping, and other treatment of the sediments are
also subject to a number of existing regulatory requirements. In both
cases, the applicable requirements vary with respect to source, activity,
location, contaminant type, and contaminant concentration.
These existing programs and requirements will provide the basic
regulatory framework for the reduction or elimination of ongoing releases of
toxic materials to the marine environment. For example, wastewater
discharges from industrial and municipal facilities have been, and will
continue to be regulated under the NPDES and state waste discharge permit
programs. Releases of hazardous substances have been and will continue to
be regulated under the state and federal hazardous waste management laws.
In most cases, discharge requirements will be similar to requirements for
comparable facilities in other parts of Puget Sound.
With respect to sediment remedial actions, greater reliance will be
placed on the CERCLA requirements and procedures. It is currently planned
that this type of remedial work will be performed by PRPs under conditions
specified in consent decrees. These negotiated agreements will be developed
in a phased approach according to priorities for action described in the
Integrated Action Plan (PTI 1988a). At a minimum, these types of corrective
measures will be performed in compliance with the substantive requirements
of existing environmental rules and regulations.
The approach being used for the Commencement Bay N/T FS is consistent
with and supportive of the major sediment quality management initiatives and
programs of the Puget Sound Dredged Disposal Analysis (PSDDA), the Puget
Sound Water Quality Authority (PSWQA), and the Puget Sound Estuary Program
(PSEP). Many of the proposed actions in Commencement Bay are dependent upon
the successful implementation of these programs. The relationships between
each of these major programs and the Commencement Bay N/T Superfund Project
are described below.
2.4.1 Relationship Between the PSDDA Program and the Commencement Bay
Superfund Pro.iect
The Puget Sound Dredged Disposal Analysis is a comprehensive interagency
effort to develop a process for making decisions regarding the unconfined
disposal of dredged material in deep waters in Puget Sound. It is a
cooperative effort undertaken by the U.S. Army Corps of Engineers, U.S. EPA,
the Washington Department of Natural Resources (DNR), and Ecology. The
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study, which began in April 1985, is a 4-yr effort being conducted in two
overlapping phases, each about 3 yr in length. Phase I covers central Puget
Sound, including the major urban centers of Tacoma, Seattle, and Everett.
Phase II, initiated in April 1986, covers north and south Puget Sound.
During the Superfund process, consistency with the PSDDA evaluation
procedures and decision guidelines has been identified as a major issue. In
the following sections, the similarities and distinctions between the two
approaches are described.
Program Objectives--
The main study objectives are to 1) identify acceptable public multiuser
unconfined, PSDDA open-water disposal sites; 2) define consistent and
objective procedures by which to determine the suitability of dredged
material for disposal at those sites; and 3). formulate site use management
plans that will ensure adequate controls and program accountability. In
contrast, the objective of the Superfund activities at the Commencement Bay
N/T site is to correct existing sediment contamination problems through
source control and sediment remedial actions.
Evaluation Procedures--
As part of the PSDDA effort, the Evaluation Procedures Work Group
(EPWG) was formed to develop a consistent decision-making framework for
evaluating dredged material and making a determination on whether the
material is acceptable for open-water disposal. The procedures developed by
this group include three tiers:
• Tier 1 - Assess existing sediment information
• Tier 2 - Conduct chemical testing if necessary
• Tier 3 - Conduct biological testing if necessary.
PSDDA and the Commencement Bay N/T FS process share two common elements:
• Use of chemical and biological testing data in the decision-
making process
• Use of the AET approach in defining sediment quality.
Use of Chemical and Biological Testing Data—The multistep PSDDA
evaluation process begins with the evaluation of existing information on
sediment contamination and sources of contamination. If there is reason to
believe that the sediments contain elevated concentrations of chemical
contaminants, then additional chemical testing of the sediments is required.
Results from this testing are used to identify sediments that are expected
to be of very high toxicity (above the PSDDA maximum level, ML) or very low
toxicity (below the PSDDA screening level, SL).
When sediment chemical concentrations fall between the SL and ML
concentrations, biological testing of the sediments is required. The
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required tests include the amphipod bioassay, the juvenile bivalve larvae
test, Microtox test, and a 30-day bioaccumulation test.
A similar approach is being proposed for use in the Commencement Bay
N/T FS. Initial estimates of cleanup areas and sediment volumes have been
based on chemical contamination. Additional chemical testing will be
required during the remedial design phase to refine sediment area and volume
estimates. PRPs will also have the option to perform additional biological
tests (including the amphipod bioassay, juvenile bivalve larvae test,
benthic infaunal analyses and/or bioaccumulation). These additional
biological tests will be used to confirm and refine sediment volume
estimates based on chemical test results.
Use of AET Values in Sediment Management Decisions—Both approaches
utilize chemical AET values in sediment management decisions. Under PSDDA,
the ML was defined as the highest AET generated from either the oyster
larvae, Microtox, amphipod, or benthic community tests. For sediments
having chemical concentrations that exceed ML concentrations, site-specific
biological testing is not required, because the material is generally
considered unacceptable for disposal at an unconfined, open water disposal
site. Dredging proponents, however, have the option of performing biological
testing to rebut this presumption.
In order to identify sediments that have very low toxicity potential,
and that are acceptable for disposal, the PSDDA screening levels were
established. In most instances, SLs were set at 10 percent of the ML
concentrations. If sediment contaminant levels are below all SL concentra-
tions, then site-specific biological testing is not required and sediments
are considered acceptable for disposal.
The Commencement Bay N/T FS cleanup goals have been established as the
lowest AET for a range of three indicators (amphipod, oyster larvae, benthic
infauna), and a measure of bioaccumulation potential. As described above
and in PTI (1988a), PRPs have the option of performing additional biological
testing during the Remedial Design phase. In general, cleanup goals fall in
between the SL and ML concentrations.
Decision-Making Guidelines--
In developing disposal guidelines, PSDDA considered seven possible site
conditions representing the relative severity of potential onsite effects at
the disposal site. Of these seven alternatives, three were evaluated in
detail: Site Condition I, representing "no adverse effects due to sediment
chemicals of concern;" Site Condition II, defined as "minor adverse
effects;" and Site Condition III, defined as "moderate adverse effects." In
laboratory terms, Site Condition I would allow "no significant sublethal,
chronic toxicity" of any kind within the site. Site Condition II would
allow "no significant acute toxicity" onsite. Site Condition III would
allow "no severe acute toxicity" onsite.
Site Condition II was chosen as the preferred management condition for
unconfined, open-water disposal at the central Puget Sound sites. Selection
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of Site Condition II was based on several factors: the relatively low
concentrations of chemicals of concern, the selection of nondispersive
sites, consistency with state water quality standards, cost-effectiveness,
and consistency with Clean Water Act Section 404(b)(l) guidelines.
In contrast to the PSDDA approach, the equivalent of the Site Condi-
tion I has been selected as the preferred condition for the Commencement Bay
N/T area. This decision was based on several factors: consistency with the
PSWQA Management Plan and the development of sound-wide sediment quality
goals, the critical nature of the shallow marine habitat in the Commencement
Bay area, and the fact that the PSDDA program was designed to address long-
and short-term problems associated with disposal of material from maintenance
dredging whereas sediment remediation in Commencement Bay is designed to
achieve long-term protection of public health and the environment.
2.4.2 Relationship Between the PSWQA Management Plan Elements and the
Commencement Bay Superfund Pro.iect
One of the PSWQA program goals is to ". . . reduce and ultimately
eliminate adverse effects on biological resources and humans from sediment
contamination throughout the Sound by reducing or eliminating discharges of
toxic contaminants and by capping-, treating, or removing contaminated
sediments . . . ." In order to achieve this goal, the 1989 PSWQA management
plan sets up a comprehensive sediment quality program. The following plan
requirements are of particular importance or relevance to the Commencement
Bay Nearshore/Tideflats FS:
• Ecology must develop standards for classifying sediments that
cause observable biological effects
• Ecology and local governments must expand efforts to assure
that ambient sediment standards will not be violated and
that sources of contaminants will be controlled
• Ecology must develop rules and sites for disposal of dredged
material
• Ecology must develop guidelines for determining when existing
sediments should be capped, excavated, or otherwise treated
• Ecology and U.S. EPA must expand the urban bay program to
provide for additional source control and consideration of
remedial actions for existing areas of high sediment
contamination.
Criteria for Classifying Sediments Having Adverse Effects (Plan Element P-2)--
Under Plan Element P-2, Ecology is required to develop and promulgate
sediment standards to identify and designate sediments that have "...
acute or chronic adverse effects on biological resources or pose a signifi-
cant health risk to humans . . ..." These standards are intended to be
sound-wide sediment quality goals and serve as the basis for preventing
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future contamination problems. Specifically, the standards will be used to
limit discharges through the NPDES and other source control programs, and to
identify sites with sediment contamination. In relation to goals established
for other programs, PSWQA (1989) noted that the standards for unconfined,
open-water disposal will probably be less stringent than those to be
developed under Element P-2 because PSDDA sites will be selected for minimal
impact, the sites will be monitored, and the effects of any contaminated
sediments will be mitigated by cleaner material also being disposed of at
the open-water sites. With respect to decisions on contaminated sediment
cleanup, PSWQA also noted that Ecology may determine it is not cost-effective
to cap, treat, or remove all sediments that do not meet the Element P-2
standards, and that higher trigger levels may need to be developed under the
remedial action guidelines.
In developing sediment cleanup goals for the Commencement Bay N/T site,
the sound-wide sediment goal was determined to be appropriate for regulating
ongoing discharges, preventing future contamination problems, and defining
cleanup areas and volumes. However, as envisioned by PSWQA, this sound-wide
goal may not be achievable in all areas under certain site-specific
conditions. If, for example, it can be shown that application of all known,
available, and reasonable technologies will not result in achievement of the
sound-wide goal at a particular site, then the remedial strategies may need
to be modified for that area.
Expand Programs to Reduce Contaminant Discharges from Industrial and
Municipal Point Sources (Plan Elements P-6, 7, 8, 14, and 20)--
A major goal of the PSWQA management program is to expand efforts to
reduce the amount of toxic pollutants released into Puget Sound by industrial
and municipal dischargers. The overall approach for achieving this goal is
1) to require that all waste discharge permits include appropriate limita-
tions on toxicants and other pollutants of concern, and 2) to devote
substantially increased resources to the inspection and enforcement of waste
discharge permits and the discovery and control of unpermitted discharges.
Preferred remedial alternatives for this FS were identified on the assumption
that such source controls would be implemented.
Develop Stormwater Management Programs (Plan Elements SW-1 through SW-4)--
The PSWQA Management Plan includes new initiatives to deal with
stormwater runoff. Similar measures are required under Section 405 of the
Clean Water Act Amendments of 1987. The major responsibilities for complying
with these new requirements rests with Ecology and local governments.
Ecology is required to prepare a series of technical manuals and
guidelines for local stormwater programs. In addition, the agency is
required to issue permits for industrial storm drains (by February 1991) and
municipal storm drains (by February 1993 for the Tacoma area). Local
governments, in turn, are required to begin stormwater program development by
December 1989, demonstrate substantial progress toward implementation by June
1991, file an NPDES permit application by February 1992, and comply with the
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permits by February 1996. The dates specified above are target dates and
are subject to change.
In the Commencement Bay N/T site, storm drains have been identified as
a significant source of contaminants in several waterways. The City of
Tacoma, the Tacoma-Pierce County Health Department, and Ecology have
developed an approach (Ecology 1986) for identifying and controlling sources
of contaminants to several storm drain systems. The continued implementation
and expansion of this program to fulfill statutory requirements will be a
critical ingredient in correcting sediment quality problems in the project
area.
Develop Confined Disposal Standards for Sediments (Plan Element S-4)--
Under Plan Element S-4, Ecology is required to develop and adopt
standards for reuse or disposal of dredged material containing concentrations
of contaminants that exceed those that are acceptable for disposal at PSDDA
sites. The standards will protect aquatic and terrestrial organisms,
including humans, from potential harm caused by contact with contaminated
sediments. The standards will be used by Ecology, shoreline jurisdictions,
and local health departments to evaluate permits for the use or disposal of
contaminated dredged material. The target date for adoption of the final
standards is July 1990.
The standards developed under Plan Element S-4 were not available for
use within the Commencement Bay N/T FS. However, the recommended remedial
alternatives are consistent with CERCLA/SARA gu.idance by providing cleanup
"which assures protection of human health and the environment." The
approach also appears to be consistent with PSWQA's intent. Remedial
alternatives for the disposal of contaminated sediments from each problem
area were evaluated according to several criteria, including protectiveness.
The recommended alternative for each area ensures a high level of protection
for environmental and human health. Long-term monitoring programs are
included within each remedial alternative to confirm the containment of
disposed sediment.
Develop Remedial Action Guidelines (Plan Element S-7)--
Under Plan Element S-7, Ecology is required to develop and adopt
guidelines for deciding when sediments that cause adverse effects should be
capped, excavated, or otherwise treated. In developing these guidelines,
PSWQA directed Ecology to consider natural recovery process, develop a
priority system, and identify trigger levels for identifying sediments
requiring expedited remedial action. PSWQA also provided some guidance on
the relationship between the sediment remedial action guidelines and the
sound-wide sediment criteria by noting that "... Ecology may determine that
it is not cost-effective to cap, treat, or remove all sediments in urban bays
that exceed the [sound-wide criteria] but may set higher (more contaminated)
trigger levels that would result in remedial actions . . . ."
Although these guidelines are not scheduled for completion until 1991,
the approach used in Commencement Bay N/T FS appears to be consistent with
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PSWQA's intent. First, the failure to meet the long-term sediment cleanup
goal in one or more areas has not automatically triggered proposals for
sediment remedial action. Instead, areas within the Commencement Bay N/T
project area were prioritized with respect to contaminant concentrations,
spatial extent of contamination, and confidence of source identification.
As discussed in Section 2.3.4, only the more highly contaminated areas were
considered for sediment remedial action. Although specific numerical
contamination levels were not established for defining which problem areas
were to be evaluated for sediment cleanup, the approach taken in defining
problem areas for remediation is consistent with the concept of a trigger
level for remedial action. In other less contaminated areas, source control
actions would be needed to ensure that these lower priority areas would
recover via natural processes within an acceptable timeframe.
Second, in evaluating sediment cleanup alternatives, the impact of
source control and natural sediment recovery processes were evaluated. As
reflected in Chapters 5-13 no additional sediment remediation is recommended
in those areas where source control and natural processes were sufficient to
correct problems in a reasonable timeframe.
2.4.3 Relationship Between PSEP and the Commencement Bay Superfund Pro.iect
The U.S. EPA Region X and Ecology, in cooperation with many other
agencies, have developed the Puget Sound Estuary Program. This is a
coordinated program designed to develop management information for Puget
Sound and to correct identified problems. PSEP tasks and studies that are
of particular importance to the Commencement Bay project include development
of sediment quality goals, and development of and support for the Urban Bay
Action Team approach.
Development of Sediment Quality Goals--
The PSEP has an ongoing project to develop sediment quality values for
use in Puget Sound. Phase I of the project was conducted in conjunction
with PSDDA. The following were three major objectives of Phase I:
• Compile and review existing chemical and biological data from
Puget Sound in order to identify statistical relationships
between sediment contaminant concentrations and empirically
determined biological effects
• Evaluate possible techniques for identifying numerical values
of chemical concentrations in sediments that are correlated
to biological effects
• Evaluate the appropriateness of using sediment quality values
in various regulatory applications.
The final report, titled "Development of Sediment Quality Values for Puget
Sound," (Tetra Tech 1986a) was completed in September 1986.
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The work performed during the Commencement Bay N/T RI laid much of the
foundation for the Phase I report. The expanded database, setliment quality
values, and additional evaluations included in the Phase I report were then
used in formulating long-term sediment cleanup goals for the FS.
Phase II of this effort was initiated in September 1987. Its primary
objective is to further test the reliability of the AET values. A final
study report was completed in September 1988 (PTI 1988c).
Urban Bays Toxics Control Program (Plan Element S-8)--
U.S. EPA and Ecology joined with other agencies and organizations in
1985 to develop and implement the Urban Bays Toxics Control Program. This
program is designed to identify known and suspected pollutant sources,
outline procedures to eliminate existing problems, and identify agencies
responsible for implementing corrective actions. The Urban Bays Toxics
Control Program was incorporated into the 1987 and 1989 PSWQA management
plans.
The primary responsibility for initiating and enforcing corrective
actions rests with the "action teams" led by Ecology. Other state and local
agencies also play key roles. The action team for a particular urban bay
area works to control or eliminate sources of toxic contaminants, utilizing
permitting mechanisms, enforcement orders, consent orders or decrees, or
court action. As sources of contaminants are controlled, attention is given
to possible remedial alternatives for areas that have contaminated sediments.
The Commencement Bay Action Team was formed in the fall of 1985. Of the
four members of the team, two work on contaminated sites and two work on
storm drains and permitted industries. In addition, existing hazardous
waste, solid waste, and water quality staff from Ecology and U.S. EPA are
used on specific projects. As of September 1987, the team had conducted 134
site inspections; assessed 7 penalties amounting to $94,000; issued 6
administrative orders; negotiated 1 memorandum of agreement, 7 consent
orders, and 2 consent decrees; and initiated permit actions at 9 sites
(Ecology 1987).
Many of the sites handled by the action team were identified as high
priority sites in the RI report (Tetra Tech 1985a), and regulatory actions
have resulted in the collection of additional data that have been incor-
porated into the FS evaluations. Specific regulatory actions have been
included in the Integrated Action Plan (PTI 1988a). The action team will
have a major role in implementing the final Integrated Action Plan.
2.5 ROUTINE DREDGING WITHIN COMMENCEMENT BAY
The Port of Tacoma is an active shipping center that receives ships
from all over the world. Total waterborne commerce through the Tacoma
harbor area has increased from 7.9 million short tons in 1975 to 15.8 short
tons in 1985. The Port of Tacoma projects that similar increases will occur
in the next 10 to 15 yr.
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Getting cargo on and off ships requires modern dock facilities with
adequate water depth. Construction of docks and maintenance of navigational
channels requires existing sediments to be excavated. Between 1970 and
1985, 2.95 million yd3 of material were dredged from Commencement Bay and
the immediate vicinity. PSDDA estimates that over 3.9 million ydj material
will be dredged from the Commencement Bay area during the next 15 yr.
When properly performed, these routine dredging activities will also
produce significant cleanup benefits by removing contaminated sediments.
Routine dredging within Commencement Bay thus represents an integral part of
the overall cleanup strategy.
During the last several years, the prospect of future Superfund cleanup
activities has inhibited the planning and implementation of routine dredging
projects. A major concern has been uncertainty regarding additional
regulatory requirements that apply to routine dredging projects in Commence-
ment Bay because it is a Superfund site.
The regulatory requirements and procedures for routine dredging
projects in Commencement Bay are discussed below. This discussion is
divided into three sections. First, the general regulatory requirements and
procedures for projects in Puget Sound are described in Section 2.5.1.
These procedures will be used for projects in the low priority Superfund
areas of Commencement Bay. These areas include Blair Waterway, Milwaukee
Waterway, the Puyallup River, and portions of the Ruston-Pt. Defiance
Shoreline. In Section 2.5.2, the procedures for projects within the nine
high priority areas are described. These involve the same basic procedures
and requirements as those for the rest of Puget Sound, with several modifica-
tions to address Superfund program concerns regarding the dilution of highly
contaminated sediments and the potential for increasing exposure to
contaminated sediments. In Section 2.5.3, the relationship between routine
dredging and sediment cleanup actions is summarized.
2.5.1 Regulatory Requirements for Routine Dredging Pro.iects in Puoet Sound
In Puget Sound, the excavation and disposal of sediments are regulated
under a number of local, state, and federal laws and regulations. At the
federal level, the Clean Water Act and the Rivers and Harbors Act of 1899
have several sections that control the dredging and disposal of sediments.
Section 404(a) of the former requires a federal permit for the discharge of
dredged or fill material into navigable waters. Guidelines for issuing
permits for discharges of dredged or fill material are specified in Parts
320 to 330 of Title 33 of the Code of Federal Regulations. This requirement
is administered by the U.S. Army Corps of Engineers. A permit is also
required under the Rivers and Harbors Act of 1899 for the "construction of
structures or the excavation or filling or other alteration or modification
of the bed or channel of the navigable waters of the U.S." In practice,
these two permit requirements are combined in the U.S. Army Corps of
Engineers permit process.
Under Clean Water Act Section 404(c), U.S. EPA can prohibit or withdraw
a permit upon determining that the discharge of dredged material will have an
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unacceptable adverse effect. In addition to U.S. EPA concurrence on the
U.S. Army Corps permit, the state must issue a water quality certification
for any project (e.g., dredging and dredged material disposal) that may cause
the violation of a state water quality standard. This certification is
granted or denied by Ecology. Details of the state's water quality
standards are found in WAC 173-201.
In administering these programs in central Puget Sound (including the
Commencement Bay area), the U.S. Army Corps of Engineers, U.S. EPA, and
Ecology utilize the testing and decision-making guidelines developed by
PSDDA. In 1988, PSDDA issued a Management Report and an Environmental
Impact Statement specifying procedures and criteria for evaluation of
dredged material and recommended locations and management procedures for
unconfined, open-water dredged material disposal sites in central Puget
Sound.
The PSDDA evaluation procedures include detailed guidelines for sediment
sampling, analysis, and data interpretation. Under these guidelines,
dredgers are required to collect sediment samples from the proposed dredging
area and perform a series of chemical and biological analyses. Based on
these data, the agencies determine whether the dredged material can be
disposed of at an unconfined, open-water disposal site.
Under the proposed Commencement Bay N/T cleanup strategy, projects in
the low priority Superfund areas would continue to be regulated under these
existing procedures and those developed to implement the Element S-4 tasks
of the PSWQA Management Plan. Key sampling and analysis requirements are
described in Phillips et al. (1988). Under those guidelines, a dredger is
required to estimate the volume of sediment for a project and the number of
"dredged material management units." A "dredged material management unit"
is defined as the smallest volume of dredged material for which a separate
disposal decision can be made. The size of a dredge management unit is
based on a consideration of dredge cut depth and potential for chemical
contamination.
In Commencement Bay, there is a relatively high level of concern with
respect to chemical contamination. Consequently, dredgers are usually
required by PSDDA to collect one sediment sample for every 4,000 yd-* of
surface sediments (0-4 ft cut depth) and subsurface sediments (defined as
deeper than 4 ft). Once the samples are collected, dredgers are required to
analyze all of the surface sediments. Subsurface samples are composited to
provide an analytical intensity of 1 sample analysis per 12,000 yd^.
Based on these test results, a determination is made on 1) whether the
dredged material can be disposed of at a PSDDA site and 2) the restrictions
(if any) on various dredging and disposal activities. In general, sediments
predicted to result in "no significant acute toxicity" or "minor adverse
effects on biological resources due to sediment chemicals" at the disposal
site are considered suitable for unconfined, open-water disposal. PSDDA
defines this level as "Site Condition II." The test interpretation
guidelines used to make project-specific disposal decisions are shown in
Table 2-7.
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TABLE 2-7. BIOLOGICAL DISPOSAL GUIDELINES FOR
ALTERNATIVE SITE MANAGEMENT CONDITIONS3
Site Condition I "No sublethal or acute toxicity" is defined as: no
one acute sediment toxicity bioassayb exhibiting a
statistically significant (P<0.05) response over
reference conditions and exceeding 20 percent
absolute mortality over control; water column
larval response does not exceed 0.01 of the LC50
after 4 h of mixing; and no bioaccumulation levels
exceeding a human health tissue guideline value.
Site Condition II No "significant acute toxicity" is defined as: no
two acute sediment toxicity bioassays exhibiting
the above conditions; and no one acute sediment
toxicity bioassay response greater than or equal
to 30 percent0 over reference conditions and
statistically significant with respect to reference
conditions; water column larval response does not
exceed 0.01 of the LC50 after 4 h of mixing; and no
bioaccumulation levels exceeding a human health
tissue guideline value.
Site Condition III No "severe acute toxicity" is defined as: no two
acute sediment toxicity bioassay responses greater
than or equal to 30 percent0 over reference and
statistically significant with respect to reference
conditions; no more than one acute sediment
toxicity bioassay response greater than or equal to
70 percent over reference and statistically signifi-
cant with respect to reference conditions; water
column larval response does not exceed 0.01 of the
LC50 after 4 h of mixing; and no bioaccumulation
levels exceeding human health tissue guideline
value.
a From Phillips et al. (1988).
b Biological tests that are used in the disposal guidelines are discussed in
Section II-6.
c Greater than 30 percent (absolute) over reference: e.g., if reference
mortality is 12 percent, test mortality cannot exceed 42 percent.
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2.5.2 Regulatory Requirements for Routine Dredging Pro.iects in the High
Priority Areas of Commencement Bay
Under the proposed Commencement Bay N/T cleanup strategy, routine
dredging projects within the nine high priority Superfund areas would
continue to be handled under the same regulatory process as projects in low
priority areas. Under the proposal, dredgers will need to obtain all
necessary permits and approvals from federal, state and local agencies. In
order to obtain the necessary permits and approvals, dredgers will be
required to satisfy the basic PSDDA testing and analysis requirements with
two modifications. These proposed modifications, which will minimize
inconsistencies between dredging projects and Superfund cleanup actions, are
described below.
Sediment Sampling and Analysis Requirements--
When conducting routine dredging in the high priority Superfund areas,
dredgers will be required to sample and analyze the top 1 ft and the next
3 ft of sediment. This modification will minimize the potential for diluting
highly contaminated surface with less contaminated underlying sediments.
Results for the top 1 ft would be evaluated separately from those for the
next 3 ft, using the PSDDA decision-making guidelines.
This modification is necessitated by the fact that the PSDDA sediment
sampling and analysis approach is based on the intentional presumption that
sediments would be acceptable (thus the sampling requirements allow for use
of routine dredging equipment, which has a vertical precision of +2 ft). In
contaminated areas such as parts of Commencement Bay, the PSDDA approach
may obscure the Superfund cleanup effort by "diluting" or mixing the problem
sediments with cleaner subsurface sediments. PSDDA acknowledged the
potential for this to occur and noted that a 1-ft cut depth and the use of
special dredging equipment may be more cost-effective (because a smaller
volume of material would be subject to confined disposal requirements) and
should be considered in cleanup areas.
Exposed Surface Guide!ines--
When conducting routine dredging within a high priority Superfund area,
the dredger will be required to sample and analyze the top 1 ft of the
newly exposed surface. If the test results demonstrate that the exposed
surface contaminant concentrations exceed those in the original surface
material, the dredger will be required to undertake additional measures to
assure that the exposed surface will have the same concentration as the
original surface or the PSDDA Maximum Level concentration, whichever is
lower.
2.5.3 Relationship Between Routine Dredging and Sediment Cleanup Actions
During the development of the FS, several interested parties expressed
concerns over the relationship between routine dredging projects and
sediment cleanup actions in high priority areas. Of particular concern was
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whether the Superfund program would require PRPs to remediate sediments that
are acceptable for disposal at a PSDDA site. These concerns are based in
part on the fact that the long-term sediment cleanup goal in Commencement
Bay is more stringent than the PSDDA guidelines. Consequently.- a portion of
the sediments within the Commencement Bay areas of concern are predicted to
be acceptable for disposal at a PSDDA site.
As a general policy, the Superfund program does not intend to require
PRPs to remediate sediments that could be taken to a PSDDA site. However,
because of the differences in exposure potential for Commencement Bay and
the PSDDA sites, there may be situations where PRPs will be required to
undertake sediment cleanup actions for sediments that pass the PSDDA
guidelines. Examples of such situations include the following: elevated
concentrations of PCBs or other contaminants that have a high potential for
bioaccumulation in a nearshore area, but demonstrate relatively low toxicity
in laboratory tests; elevated concentrations of contaminants that are highly
toxic to benthic communities but exhibit relatively low toxicity in
laboratory tests; highly contaminated surface sediments with relatively
clean underlying sediments; and elevated contaminant concentrations with low
sedimentation rates. Based on available sediment data, it does not appear
that problem sediments requiring remediation will pass the PSDDA guidelines.
If they do pass, dredged material removed as a result of a Superfund
enforcement action will need to be taken to a non-PSDDA site.
2.5.4 Conclusions
Under the proposed approach, routine dredging projects will continue to
be regulated under existing federal and state regulatory programs. The
primary basis for decisions on the disposal of dredged material will be the
PSDDA and Element S-4 procedures. However, for dredging projects within the
nine Commencement Bay problem areas, the PSDDA procedures would be modified
to incorporate a more precise sampling and analysis program. This modified
approach would require dredgers to separately sample and analyze sediments
from the top 1 ft and next 3 ft of sediment. These procedures will reduce
the potential for diluting the higher contamination levels present in the
surface sediments with underlying sediments containing low concentrations.
In addition, the top 1 ft of the eventual exposed surface (below the
overdepth) should be routinely analyzed. If the surface to be exposed
exceeds the contamination of the original surface, the dredger should
undertake additional measures to assure that the exposed surface will have
the same concentration as the original surface or the PSDDA maximum level,
which ever is lower.
Sediment cleanup actions will be handled under federal and state
Superfund programs. Potentially responsible parties will be required to
perform additional sediment testing to refine estimates of sediment volumes
and then perform sediment cleanup. Specific actions will, at a minimum,
comply with the PSDDA guidelines and Element S-4 requirements. In general,
Superfund cleanup actions will not be required for sediments which are found
to be acceptable for disposal at a PSDDA site. These cleanup actions will be
coordinated with routine dredging projects to ensure cost-effective cleanup
solutions.
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3.0 REMEDIAL TECHNOLOGIES FOR DEVELOPMENT OF
AREA-WIDE SEDIMENT REMEDIAL ALTERNATIVES
Technologies that are potentially applicable to the remediation of
contaminated media in the Commencement Bay N/T study area are evaluated in
this section. The results of this evaluation are used to select remedial
alternatives which are composed of institutional controls and remedial
technologies applicable to the cleanup of a contaminated site. Remedial
technologies are described in detail in the beginning of this section.
Sediment remedial alternatives are presented in the latter parts of the
section.
During the evaluation of remedial technologies, both source control and
sediment remedial technologies are evaluated, as control of contaminant
sources is an essential element of the overall approach to cleanup of
problem sediments. The purpose of the evaluation is to screen or eliminate
from further consideration technologies that are inappropriate based on
technical implementability, given the nature and extent of contamination and
physical characteristics at the site. Approaches to remediation fall into
six general categories: no action, institutional controls, containment,
removal, treatment, and disposal.
Consideration of no action is required by the NCR and provides a
baseline from which to evaluate the effects of responses that directly
address the cleanup or isolation of contaminated materials. Under the no-
action approach, potential contaminant sources would be subject only to the
regulatory controls that would have been initiated in the absence of the
RI/FS process (e.g., conventional NPDES permitting procedures). Institution-
al controls involve limiting the potential for public exposure to site
contaminants by such means as educational programs and site access re-
strictions. Under the institutional controls approach, contaminant sources
would be subject to regulatory controls addressing identified sediment
contamination problems that, while allowable under existing effluent
permitting and waste management programs, would not have been implemented in
the absence of the RI/FS (e.g., prohibitions in new or modified NPDES
permits against discharge of problem chemicals found in the sediments). In
the case of the Commencement Bay N/T area, the institutional controls
response action involves no cleanup of contaminated sediments.
The remaining approaches all involve aggressive contaminated sediment
control as a key element. Containment response actions involve in situ
sediment capping or lateral barriers to isolate contaminants from the
environment or to preclude the introduction of additional contamination into
sensitive areas. Removal response actions include dredging of contaminated
sediments prior to disposal or treatment and disposal. Treatment of
contaminated media is an element of response actions intended to significant-
ly reduce contaminant concentrations, mobility, and toxicity, and may be
applied either in situ or following removal operations. Disposal of
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sediments or treatment by-products is the final general category of
response. The containment, removal, treatment, and disposal approaches also
incorporate aggressive source control regulatory activities specifically
oriented toward the sediment remediation and subsequent maintenance of long-
term sediment quality in the Commencement Bay N/T study area.
Response actions may be used alone or in concert with one another.
Each general response action may comprise one or more technology type. For
example, treatment responses can involve physical, chemical, or biological
technologies. In addition, each technology type may represent one or more
specific process options.
Sediment remedial technologies are evaluated in Section 3.1 and
potential source remedial technologies are evaluated in Section 3.2.
Emphasis, however, is placed on the former. The goal of the evaluation is
to select applicable technology types and representative process options
suitable for the development of sediment remedial alternatives for the
Commencement Bay N/T site.
Area-wide remedial alternatives are presented for Commencement Bay
sediments that exceed target cleanup goal concentrations. The development
of alternatives is conducted in two steps. The first step is creation of
generic alternatives based on viable general response actions (Section 3.3).
The second step is creation of specific alternatives from the technology
types and process options that are most applicable to sediment remediation
in the Commencement Bay N/T study area (Section 3.4). According to the
intent of draft CERCLA/SARA guidance, the objective of a feasibility study
is to obtain a set of remedial alternatives representing all technology
types considered suitable for evaluation.
3.1 GENERAL RESPONSE ACTIONS FOR SEDIMENTS
Potential sediment remedial technologies and associated general
response actions are presented in Figure 3-1. Capping is the only technology
type considered for in situ containment of contaminated sediments. Although
dredging is essentially the only technology for removal of sediments,
several categories of dredging are discussed. The treatment response
action is divided into two categories: in situ and post-removal treatment.
Disposal technologies, implemented post-removal, are categorized as either
confined or unconfined.
3.1.1 No Action
The no action alternative provides a baseline against which other
sediment remedial alternatives can be compared. Under this alternative, the
problem area remains unchanged, and nothing is done to mitigate public
health and environmental risks. No source control measures are implemented
under this alternative beyond those required under existing regulatory
programs. Adverse biological and potential public health impacts continue
at preremediation levels.
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GENERAL
RESPONSE ACTION
TECHNOLOGY TYPES
PROCESS OPTIONS
Sediment | Clay/Sand/Gravel
Synthetic Membrane [ Sorfaents
Clamshell | Dragline [ Bucket Ladder [ Dipper |
Cutterhead ] Buckelwheel | Suction | Dustpan | Hopper
\ Mud Cat | Cleanup | Refresher | DREX | Waterless |
Backhoe Loader
IN SITU
TREATMENT
Solidification/Stabilization
POST-REMOVAL
Chemical Transformation
Biological Treatment
I Solidification/Stabilization]
Chemical Treatment
Biological Treatment
i Thermal Treatment
Physical Treatment
DISPOSAL
Unconfined
Confined
Grouts | Gels | Sealants | Sorbenls |
Oxidation Dehalogenation
Sorbents
Grouts
I
Gels
Vitrificaiion
Thermoplastic Processes | Pozzolanic Processes
Sealants
Oxidation/Reduction [ Dehalogenation | Hydrolysis | Photolysis
Neutralization | Ion Exchange | Precipitation
Composling
Land farming
Fixed Film
Suspended Growth
Rotary Kiln
Multiple Hearth
FluidizedBed Infrared
Misc.
Dewatering
Solvent Extraction
Filtration
Sorption | Solids Fractionation | Sedimentation
Open Wafer [
Aquatic I Nearshore Upland |
Figure 3-1. Response action, technology types, and process
options for remediation of contaminated sediments.
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3.1.2 Institutional Controls
Institutional controls involve nonstructural practices to reduce public
contact and possible health effects associated with contact with contaminated
materials. Institutional controls include use and access restrictions such
as identification and posting of "no fishing" areas. Hazard education and
public awareness programs can also be used as methods of institutional
control. Programs of this type have been shown to be quite successful, as
discussed in Section 3.2.2. Monitoring programs to identify trends of
contamination and improve the general understanding of the problem can also
be included in a broad definition of institutional controls.
3.1.3 In Situ Containment
In situ sediment containment strategies such as capping are designed to
isolate contaminated sediments without removing them. Typically, clean fill
material suitable for recolonization by benthic organisms is used to cover a
contaminated sediment zone. The cap is thick enough to preclude significant
contaminant migration by physical processes and bioturbation. Split-hulled
barges and hydraulic conveyance systems for slurried dredged material have
been used for in situ capping of sediments. This equipment was originally
developed for dredging operations involving unconfined aquatic disposal of
dredge spoils. Specialized equipment for placement of capping materials
with minimum turbidity (e.g., diffusers) has been developed (U.S. Army
Corps of Engineers 1986b). Descriptions of capping strategies, their
effectiveness, implementation considerations, and examples of field applica-
tions are presented in Appendix B.
Capping is retained as an appropriate remedial measure for contaminated
sediments in Commencement Bay, except where periodic dredging is required to
maintain channel depths or where the geomorphic surface is unstable because
of slumping or erosion. Potentially applicable capping options include the
use of uncontaminated dredge spoils, the use of clean fill from terrestrial
sources, and the use of low permeability additives in the capping material.
Such additives either react with or hydraulically isolate the sediments of
concern and further reduce the potential for contaminant migration.
3.1.4 Removal
A wide range of dredging technologies has been developed to address
different aspects of sediment removal. The following discussion summarizes
the findings of the U.S. Army Corps of Engineers report entitled Evaluation
of Alternative Dredging Methods and Equipment. Disposal Methods and Sites.
and Site Control and Treatment Practices for Contaminated Sediments (Phillips
et al. 1985), and integrates other pertinent literature.
Mechanical Dredges--
Mechanical dredges remove materials through the direct application of
mechanical force to dislodge and excavate bottom sediments. Types of
mechanical dredges include clamshell, dragline, bucket ladder, and dipper
dredges. Descriptions of these .dredges are presented in Appendix B. The
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clamshell dredge is considered the only mechanical dredge suitable for
removal of contaminated sediments (Phillips et al. 1985); resuspension and
loss of sediment due to mechanical disturbance is unacceptable with the
others.
Clamshell dredges are usually mounted on a barge and are available in
bucket capacities of 1 to 18 yd^. Production rates exceeding 600 yd-Vh are
possible with the large buckets. Dredged material is transferred to a
separate barge for transport to a treatment area or disposal site. Depending
on the production rate and the distance from the dredge site to the treatment
or disposal site, the use of two barges could permit nearly continuous
operations.
Clamshell dredges are capable of removing sediments at depths of
greater than 100 ft, which makes it a feasible dredging technique for all
problem areas in Commencement Bay. Depending on operator experience, depth
accuracies of 1-2 ft can usually be achieved. The equipment is highly
maneuverable and can operate effectively in confined areas or in debris-
laden sediments. A significant advantage of clamshell equipment is its
ability to maintain nearly in situ sediment densities. This feature results
in fewer dredge water management problems compared to hydraulic dredging
(see below) and, generally, less handling of material.
Conventional clamshell dredging resuspends approximately 2 percent of
the total sediment mass dredged (Tavolaro 1984), which is cause for concern
when the sediments are contaminated. The resuspended material is distributed
throughout the water column. A watertight clamshell concentrates resuspended
material near the sediment-water interface. However, watertight clamshells
produce dredged material with a significantly higher percentage of water than
conventional clamshells, which may increase the need for management of
contaminated dredge water.
Because the percentage of sediment resuspended by clamshell dredging is
only 2 percent or less, and since the majority of the contaminants in
Commencement Bay sediments are particle-bound, solubilization of contaminants
into the water column is not expected to be significant. Aside from the
obvious visual impacts associated with sediment resuspension, actual
environmental impacts must be evaluated on a case-by-case basis to determine
the degree to which sediment contaminants are released into the water
column. Operational steps that can be taken to reduce the extent of
sediment resuspension include controlling the drop speed, hoist speed, and
swing of the bucket; preventing the bucket from dragging along the bottom;
and preventing barge overflow. Additional measures such as cofferdams and
silt curtains may be necessary, however, to contain resuspended sediment
around the dredging area.
Cofferdams are installed when hydraulic isolation of an area of
contaminated sediment is desired. Typically, the use of cofferdams is
limited to locations with shallow water depths (typically under 10 ft). For
this reason, Wheeler-Osgood Waterway may be the only problem area where use
of a cofferdam is feasible. This waterway is relatively inactive and much
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of it is intertidal. Conversely, most waterways in Commencement Bay are at
least 25 ft deep with active shipping traffic.
Silt curtains installed around the dredging site will trap suspended
solids and debris generated during dredging. Silt curtains are usually
constructed of nylon-reinforced polyvinylchloride membranes in 90-ft
sections. The sections are joined together at the site to provide the
desired length. Silt curtains can be installed in several configurations,
depending on site-specific needs. Circular configurations would most likely
be necessary in Commencement Bay because the tidal influence reverses flow
in the waterways. Silt curtains normally do not extend below the surface by
more than 4-5 ft, but theoretically could be extended to greater depths.
Silt curtain effectiveness is considered questionable (Malek, J., 17 December
1987, personal communication) but should be evaluated further as a turbidity
control measure.
Both conventional and watertight bucket clamshell dredging are readily
implementable technologies and are retained for further evaluation for the
removal of contaminated Commencement Bay N/T sediments.
Hydraulic Dredges--
Hydraulic dredges are barge-mounted systems that employ diesel- or
electric-powered centrifugal pumps to remove and transport sediments in a
liquid slurry. The dredges may either be self-propelled or require towing
between dredging sites. Hydraulic dredges evaluated include the bucket-
wheel, suction, cutterhead, dustpan, and hopper models. Descriptions of
these dredges are presented in Appendix B.
Hydraulically dredged sediments are removed by suction. In all but the
most unconsolidated materials, suction must be preceded by some mechanical
action to dislodge the sediments. A suction head is mounted on an adjustable
ladder to facilitate depth control during the dredging operation. Hydraulic
dredge capacities are generally classified according to the diameter of the
discharge line: small dredges have 4- to 14-in diameter discharge lines,
medium dredges have 16- to 22-in diameter discharge lines, and large dredges
have 24- to 36-in diameter discharge lines. Production rates range from
70 to 1,875 yd3/h. Single-pass excavation depths range from 18 to 36 in.
Sediment slurries are pumped into bins or hoppers on the dredges, into
barges tethered alongside of the dredge, or through floating or pontoon-
supported discharge lines (pipelines) to a disposal or treatment site
(Phillips et al. 1985). For transport distances exceeding 2 mi, booster
pumps may be required. Other conditions (e.g., coarse sediments, small
dredges) may also necessitate the use of booster pumps.
Because sediment disturbance is confined to the bottom and because the
dredged material travels through the water column within an enclosed
pipeline, hydraulic dredging methods usually generate less turbidity at the
dredging site than mechanical methods. The degree of resuspension varies
with the type of hydraulic dredge, operational controls, and sediment
characteristics. The pipeline cutterhead dredge is reported to resuspend
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approximately 1 percent of the dredged sediment mass (Hayes 1985).
Specialized head adaptations are available to reduce resuspension of solids
(see following discussion). Improved operational controls can be implemented
to further reduce resuspension. Unlike mechanical dredges, hydraulic dredges
cannot remove large objects and debris (e.g., drums and scrap metal) from
waterways. Hydraulic dredges are typically more accurate than mechanical
dredges, with accuracies on the order of +0.5 ft.
Hydraulic dredges produce slurries of 10-20 percent solids by weight.
Nearshore or upland disposal of this material will require removal of solids
from the dredge water (e.g., by sedimentation) and possibly additional
treatment of that water. The need to remove additional suspended solids or
soluble contaminants must be assessed on a case-by-case basis.
The hydraulic dredges listed previously are not all appropriate for the
Commencement Bay N/T project. Only the cutterhead is retained for further
evaluation. The dustpan dredge is eliminated because it is most effective
for the removal of free-flowing granular sediments such as sand and gravel
in rivers, and tends to generate excess turbidity. Hopper dredges are
eliminated from further consideration because they cannot dredge sediments
from around piers, docks, or other structures—areas where some of the
highest concentrations of problem chemicals were observed in Commencement
Bay. Also, hopper dredges are not appropriate for the removal of con-
taminated sediments: the economically preferable mode of operation
involves overflow of the hopper, which would generate excessive suspended
solids. Likewise, the bucketwheel and suction dredges have been eliminated,
as discussed in Appendix B.
Specialized Design Dredges--
Variations of conventional hydraulic dredges have been developed during
the last few years in Japan, Europe, and the U.S. These variations have
been driven by the need for special applications, improved performance,
mitigation of negative environmental impacts, and economic advantages.
There are many specialized dredges on the market, in various stages of
development, that pump high solids, produce Tow turbidity, or both.
Specialized dredges include portable dredges (e.g., mud cat, mini dredge,
dragon) and specialized head adaptations (e.g., DREX, cleanup, refresher,
and waterless). Some models, such as the mud cat, have the characteristics
of being portable and using a special head adaption. Descriptions of the
mud cat and the specialized dredging heads are presented in Appendix B.
The availability of a specialized dredge depends primarily on whether
it is a foreign or domestic technology. If a specialized design is not
marketed domestically, its use may require a specific international,
government, or private agreement (Phillips et al. 1985). Production may be
restricted to a small number of units because of the limited application of
some designs. Availability of these specialized units is likely to be
unfavorable if the demand exceeds the current supply. Additionally, new and
emerging designs may be limited to a few test models. These factors
influence the availability of a special design and dictate the initial and
mobilization costs. However, technologies with limited availability should
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not be rejected on the basis of initial costs alone, since the overall
economic feasibility is determined by analysis of all costs, including
operation and maintenance of all equipment; transportation, treatment, and
disposal of dredged material; labor; and other project-related expenses.
Specialized dredges may prove to be economically competitive with conven-
tional methods as the initial costs are amortized.
As an example of this type of dredge, the mud cat is retained for
further evaluation of its specific application to shallow-water sites. The
availability of the cleanup and refresher dredging heads (designed by
Japanese firms) and the waterless dredge (designed by the American firm
Waterless Dredge Company) should be reevaluated prior to scheduled dredging.
Limited availability of these dredging heads may result in higher mobiliza-
tion and initial costs. Limited availability must be weighed against the
advantages in reduced sediment resuspension and maximized solids content of
dredged material.
Excavation--
Operating principles of backhoes and loaders are summarized in
Appendix B. Backhoes and loaders have limited application to the removal of
submerged contaminated sediments primarily because they generate substantial
amounts of suspended solids. This equipment may be useful for onshore
dredged material management but is not retained for further consideration for
sediment removal.
3.1.5 Treatment
In Situ Treatment--
Technologies potentially applicable to the in situ treatment of
sediments may be grouped into the following categories:
• Stabilization/solidification
• Chemical
• Biological.
Thermal and physical treatment technologies are not applicable to the in
situ treatment of contaminated sediments because they cannot be performed in
place for submerged sediments.
Stabilization and solidification technologies, which are detailed below
for possible application in the treatment of contaminated dredged material,
are unproven for in situ remediation of contaminated sediments underwater.
Sediments have been solidified to improve bearing capacity (Otsuki and Shima
1984), but the applicability of this technology to in situ contaminant
immobilization is relatively unexplored (Francingues 1985). It is possible
that an innovative solidification process could be developed for use in
conjunction with capping to substantially cut off dispersive pathways of
contaminant migration (e.g., via diffusion, bioturbation, or erosion
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processes). Therefore, solidification is retained as an innovative
technology within the context of in situ containment via capping.
Successful in situ chemical treatment of contaminated sediments has not
been documented. However, chemical treatment options have been studied for
in situ treatment applications. During initial screening of remedial
technologies for PCB-contaminated sediments in the upper Hudson River, ultra-
violet ozonation and chemical treatment (e.g., dechlorination) were con-
sidered, but rejected as unproven (NUS 1983). Dechlorination involving
reaction of potassium hydroxide and polyethylene glycols was fully evaluated
both for remnant sediments exposed when the river level dropped and for
dredged material. Reagents would need to be rototilled into the exposed
sediments and several applications might be necessary. This procedure would
have limited in situ application even with hydraulic isolation because of
the possible length of time required to reduce PCB levels adequately.
For submerged sediments, implementation of a chemical treatment process
is complicated by the presence of overlying water. In addition, sediments
contaminated with a complex set of pollutants would probably require more
than one treatment step, and the production of undesirable by-products would
be a distinct possibility. This is particularly relevant for the Commence-
ment Bay study area, where sediments are frequently contaminated with a
variety of organic and inorganic constituents. From the standpoint of
implementability, in situ chemical treatment of contaminated sediments is
impractical and is not retained for further evaluation.
No reports of enhanced in situ biological treatment of contaminated
sediments were found. For this reason, in situ bioreclamation is not
retained for further evaluation.
Post-Removal Treatment--
Technologies potentially applicable to the treatment of dredged
sediments are considered in this section. Post-removal treatment represents
an intermediate step between removal and disposal, and is intended to reduce
contaminant concentrations, mobility, or toxicity. Treatment technologies
discussed in this section fall within the following categories:
• Solidification/stabilization
• Chemical
• Biological
• Thermal
• Physical.
Post-removal management of sediments prior to disposal may require treatment
of the sediment slurry as a whole, treatment of dewatered sediment solids,
or treatment of the water removed from the sediment slurry.
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Solidification/Stabilization—Stabilization and solidification _ are
designed to improved waste handling characteristics, reduce contaminant
mobility, or alter the solubility or toxicity of waste constituents
(U.S. EPA 1986a). Specifically, stabilization involves the addition of
materials to reduce contaminant mobility in solid waste, primarily by
removing free water through hydration reactions. Handling characteristics
are generally improved by stabilization processes. Solidification processes
result in the consolidation of a solid waste into much greater aggregate
sizes, sometimes resulting in a monolithic block, which possess significantly
greater structural integrity. Solidification and stabilization are
effective in reducing the mobility or leaching potential of contaminants
that have a strong tendency to migrate from the original media with which
they are associated. As a result of insoluble hydroxide formation, metals
are particularly well suited to immobilization in cement or pozzolanic
(cement-like) systems. Particle-associated organic contaminants are
restricted from leaching through physical encapsulation, but little evidence
is available on the leaching potential of specific organic contaminants from
solidified or stabilized wastes (U.S. Army Corps of Engineers 1986a).
Stabilization and solidification are not mutually exclusive treatment
approaches, and several techniques utilize characteristics of both. The
main categories of stabilization and solidification technologies are as
follows:
• Sorption
• Lime-fly ash pozzolan processes
• Pozzolan-Portland cement processes
• Thermoplastic microencapsulation
• Vitrification.
Sorption—Sorption techniques can involve both absorptive and adsorptive
processes. Absorptive processes are used primarily to reduce the moisture
content of a waste material, thereby permitting the waste to be disposed of
as a solid. In contrast, adsorption involves the molecular adhesion of
contaminants to sorptive materials. The most common sorptive materials
include relatively inexpensive industrial waste products such as bottom ash,
fly ash, or kiln dust from the manufacture of cement and lime. Natural
materials that may be considered include clay minerals (e.g., zeolites and
bentonite). Activated carbon, alumina, and a host of synthetic materials
may be considered as well. Ideally the sorbent selected for a particular
use should be unreactive, npndegradable, and compatible with the waste
constituents. For dredged sediment disposal in an upland site, stabilization
by sorption, perhaps in conjunction with another process, might be con-
sidered. However, there are no reports of the use of sorption methods in
conjunction with contaminated dredged material disposal.
Fly Ash Pozzolan Processes--Lime-flv ash pozzolan treatment of hazardous
wastes involves mixing the waste with a pozzolanic fly ash (high silicic
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acid content) and hydrated lime. The resulting material is either packed in
molds for curing or placed in a landfill. It is an inexpensive solidifica-
tion process, but usually results in a material with greater leaching
potential than occurs with cement-based systems. Hazardous wastes treated
by this process often cannot be delisted. Applications of this technology
for dredged sediments have not been reported.
Pozzol an-Portl and Cement—Port 1 and cement can be blended with a
pozzolanic fly ash to yield a stronger concrete-like product. Actual
solidifying formulations can vary from those containing no pozzolanic
material to those containing additives such as solvents, surfactants,
emulsifiers, and clay minerals. These additives improve binding strength or
reduce the mobility of waste constituents in the porous product. The most
suitable formulation depends on waste chemical characteristics and the
reactivity of waste constituents with cementing agents. Cement-based
solidification and stabilization systems have not been field-demonstrated
for treatment of contaminated dredged material.
Thermopl astic Mi croencapsul at ion—Thermoplastic microencapsulation
involves the mixing of heated and dried wastes with a thermoplastic material
such as polyethylene, paraffin, or asphalt bitumen that cools to form a
solid mass suitable for landfill disposal. The technology is very expensive
to implement and has a considerable air pollution potential. The process is
generally reserved for wastes that are difficult to treat by any other
means. Thermoplastic microencapsulation has been successfully used for the
disposal of nuclear wastes and has been proposed for use in disposing of
certain industrial wastes such as arsenicals. There have been no attempts
to apply this technology to treatment of contaminated dredged material.
Vitrification—Vitrification is an energy-intensive process whereby
fusable components of a waste (silica, alumina) are melted under the
influence of an electrical current. When cooled, the treated material
becomes a solid glass-like mass, effectively immobilizing inorganic constit-
uents. Organic constituents tend to be pyrolyzed within the molten mass,
emerge above the surface as gas, and are oxidized during the high-temperature
process. Therefore, the potential for air emissions must be addressed when
considering vitrification. The technology was originally developed for the
solidification and immobilization of low-level radioactive metals contamina-
tion in soils. No contaminated dredged material applications have been
reported.
The use of stabilization and solidification technologies as a part of
contaminated dredged material remediation projects has not been reported in
the literature but has recently been explored in pilot studies. Prior to
implementation of stabilization or solidification processes, bench-scale
testing would be required to evaluate effectiveness in meeting remediation
objectives. Conceptually, however, either stabilization to reduce moisture
content or solidification to both reduce moisture content and immobilize
contaminants would be appropriate for consideration in conjunction with
post-removal sediment disposal operations. Formulations most appropriate
for consideration for the treatment of contaminated dredged material are
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sorption, lime-fly ash pozzolan, and Portland cement-pozzolan systems. In
addition, proprietary formulations could also be suitable.
The U.S. Army Corps of Engineers (1986a) tested sediments from Everett
Harbor, using cement, fly ash, lime/fly ash, and a proprietary additive,
Firmix. Arsenic and zinc were completely immobilized (U.S. Army Corps of
Engineers 1986a). Certain process formulations reduced the leaching of
cadmium, chromium, and lead by 93 percent. No information was obtained on
the Teachability of specific organic contaminants following treatment.
Pilot-scale solidification tests are underway as part of the New Bedford
Harbor feasibility study (Cullinane, J., 8 January 1988, personal communica-
tion) .
Various approaches have been considered for the implementation of
solidification/stabilization technologies in the treatment of contaminated
dredged material (Ludwig et al. 1985; Francingues 1985). All scenarios
involve a confined nearshore or upland disposal facility. Disposal of
solidified contaminated dredged material in a confined aquatic disposal site
has not been considered. Disposal of solidified coal ash and scrubber
sludge (by-products of coal combustion) in water has been conducted (New
York State Energy Research and Development Authority 1985). This waste has
a high metals content. In a study on treatment and disposal of this
material in water following solidification, the physical integrity of the
solidified mass remained intact and leaching rates were negligible to low
over the 3-yr study period. However, the high salt content (e.g., chloride,
magnesium) of marine sediments would be expected to extend the curing time
required for effective solidification/stabilization. The need to stage
sediments while curing takes place may preclude implementation of this
option for in-water disposal of solidified sediments when large volumes of
sediment are involved. Although it has not been attempted before, solidifi-
cation or stabilization agents could also be added to contaminated dredged
material on a barge, using specially designed portable mixing equipment
(Willet, J., 6 April 1988, personal communication). The slurry mixture
would be returned to the aquatic environment with a hydraulic pump following
the addition of solidification agents. The sediment return mechanism would
need to be carefully engineered to minimize disturbance and dissociation of
solidification agent and sediment. The stabilization/ solidification
process for marine sediments would require field testing before implementa-
tion. Therefore the treatment of contaminated dredged material using
stabilization/solidification technologies is considered here as an innovative
technology.
Chemical Treatment--
Chemical treatment options are considered here for potential application
in the remediation of contaminated dredged material. In general, chemical
treatment technologies are appropriate for aqueous and liquid chemical
wastes that are reasonably uniform in composition. Solid wastes are rarely
treated by chemical means. For complex wastes containing a variety of
contaminants, chemical approaches are generally less favorable than other
treatments in that incomplete reactions and the formation of by-products
often require that .multiple treatment steps be included. Applications of
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chemical treatment for contaminated soils are under development (U.S. EPA
1986c), but none have been reported for treatment of contaminated dredged
material (U.S. Army Corps of Engineers 1986c). The most appropriate context
in which to consider chemical treatment is during management of contaminated
dredge water generated during dewatering operations.
Water generated as a result of sediment dredging or dewatering (i.e., as
a part of post-removal sediment treatment) is likely to contain relatively
dilute concentrations of both organic and inorganic contaminants, and may
require treatment prior to discharge to a receiving water. The following
technologies are reviewed for their applicability to the treatment of dredge
water removed from contaminated dredged material:
• Hydrolysis
• Neutralization
• Photolysis
• Oxidation and reduction
• Precipitation
• Ion exchange.
Hydrolysis, neutralization, and photolysis are probably not applicable
to the problem chemicals in Commencement Bay sediments. Hydrolysis has been
used to destroy carbamate and organophosphorus pesticides, neither of which
is a contaminant of concern in Commencement Bay sediments. Neutralization
is used to adjust pH in highly acidic or alkaline waters, conditions not
associated with contaminated marine sediments in Commencement Bay. Photo-
lysis has been used to reduce concentrations of dioxins and other polychlori-
nated organic compounds. It is unlikely that concentrations of these
compounds are high enough in the problem sediments to require treatment.
Chemical oxidation has been used to detoxify cyanide and to treat
dilute aqueous wastes containing oxidizable organics. Organic compounds for
which oxidative treatment has been reported include aldehydes, mercaptans,
phenols, benzidine, unsaturated acids, and certain pesticides. Oxidation
has been used to pretreat recalcitrant compounds prior to biological
oxidation. The primary drawbacks of the technology are that incomplete
oxidation and by-product formation may not result in adequate detoxification
of the material. From an operational standpoint, the oxidants are very
hazardous and require great care in handling. Oxidation methods are
unlikely to be applicable to the treatment of contaminated dredge water.
Reduction techniques have been used to remove mercury and lead, and to
reduce hexavalent chromium. They are used primarily in the electroplating
and metal finishing industries. There have been no reported uses of
reduction technology for organic compounds.
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Chemical precipitation through the addition of a coagulating agent is a
technology suitable for consideration in eliminating metals from solution.
The technology is not applicable to the removal of organic compounds.
Chemical precipitation has been used to treat aqueous wastes containing zinc,
arsenic, copper, mercury, manganese, cadmium, trivalent chromium, lead, and
nickel. It is a commercially available technology and its use is widespread.
Precipitation methods are sensitive to changes in waste stream composition,
and formation of organometallic complexes can limit removal efficiency.
Chemical precipitation methods have usually been applied to contaminated
fresh water.
Ion exchange involves the replacement (exchange) of ions electro-
statically held to the surface of a solid with similarly charged ions in
solution. The solid medium, usually referred to as a resin, can be made
selective for ions of both positive and negative charge. Resins selective
for heavy metals (e.g. copper, lead, mercury) are available. The technology
is not applicable to the removal of neutral organic compounds from solution.
If dredge water must be treated for both metals and organics, two process
steps would be required.
Ion exchange is generally intended as a polishing step to reduce the
concentrations of ions from 1-100 ppm to a few ppb. Water produced during
the dredging of contaminated sediments from Commencement Bay is likely to
contain metals within or below this range of treatable concentrations. Feed
solutions for ion exchange systems must have low suspended solids concentra-
tions (less than 5 Nephelometer Turbidity Units), which could necessitate a
prefiltration step. The effects of high salinity on resin performance would
need to be evaluated. The potential for resin biofouling resulting from
biodegradable organic compounds in the feed must also be considered.
Chelating agents, both organic and inorganic, could severely reduce exchange
efficiency. An acidic solution requiring further treatment would be produced
as a result of resin regeneration. One possible regenerant treatment
strategy would include precipitation and filtration, with return of the
filtrate to the exchange system and disposal of the sludge. However,
because the high salinity would be expected to hinder resin performance, ion
exchange is not considered to be applicable for treatment of dredge water
from Commencement Bay.
Biological Treatment--
Biological treatment technologies can be applied to both dredge water
and dredged sediment. Biological wastewater treatment technologies are
appropriate for the removal of biodegradable organic compounds from waste-
water and are not intended for removal of metals. Even so, some metals are
removed by adsorption or incorporation into the suspended or fixed biomass
that eventually emerges in the sludge. Treatment for both categories of
contaminants will generally require more than one process step. Many
industrial wastes and the majority of municipal wastes are treated bio-
logically. Methods used for the treatment of these wastewaters are
applicable to many hazardous wastes and are finding acceptance as treatment
alternatives. Biological treatment techniques for dilute aqueous solutions
containing organic contaminants are reviewed in Section 3.2.1.
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The single biological treatment option potentially applicable to
contaminated sediments is land treatment. Land treatment is the controlled
application of a waste into the biologically active upper zone of a soil and
the maintenance of conditions optimal for microbiological activity. In
addition, the amount of waste applied to the soil is controlled so that the
cation exchange capacity of the soil (i.e., the capacity of the soil to im-
mobilize metals) is not exceeded. Generally the natural microflora is expec-
ted to acclimate to the amended soil conditions, but microbiological seeding
is sometimes considered. A fundamental objective of land treatment is to
avoid permanent or long-term contamination of the treatment soil so that it
may be considered for any potential use following the treatment period.
Land treatment of contaminated marine sediments has not been reported.
Problems associated with salinity may require mitigation prior to or
following application of the sediment. Land treatment is not suitable for
wastes containing recalcitrant compounds such as PCBs, and must be limited to
wastes for which degradation of hazardous constituents can be demonstrated.
Runoff and leaching of contaminants to groundwater must be considered during
facility design. The major drawback to land treatment as a sediment treat-
ment alternative is the potentially excessive land areas that would be
required to handle the large volumes of dredged sediments. However, because
land treatment provides a viable biological treatment option, it is retained
for further consideration.
Thermal Treatment--
Thermal treatment processes are designed to destroy combustible organic
wastes. They are also used to eliminate hazardous organic contaminants in
low concentrations from incombustible materials such as soils. The elimina-
tion of hazardous organic constituents from marine sediments by incineration
has not been reported but, in theory, is feasible. Thermal processes are
not suitable or economical for the treatment of water containing low
concentrations of organic constituents and are only discussed in conjunction
with treatment of dewatered sediments.
Incineration is the most common thermal treatment technology. The
conventional process options include liquid injection, multiple hearth,
fluidized bed, rotary kiln, and infrared incineration systems. Large, perma-
nent systems are capable of handling approximately 500 tons/day (Breuger, J.,
19 January 1988, personal communication). This process rate is approximately
equivalent to between 270 and 420 yd3/day, depending on total solids content
of the sediment. Emerging technologies include the following:
• Molten salt
• Wet air oxidation
• Plasma arc torch
• Pyrolysis
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• High temperature fluid wall
• Supercritical water
• Advanced electric reactor
• Vertical tube reactor.
In general, these emerging technologies are not suitable for consider-
ation as treatment options for contaminated marine sediments. Molten salt
incineration is intended primarily for the treatment of small quantities of
liquid and solid organic wastes with a low ash content, and has been
demonstrated to be highly effective for the destruction of chlorinated
hydrocarbons and some pesticides. Wet air oxidation is designed for the
treatment of concentrated aqueous organic wastes. Plasma arc systems are
still largely under development and are intended to treat small quantities
of liquid wastes at extremely high temperatures (>10,000° C). Pyrolysis
involves the heating of wastes in an oxygen-deficient atmosphere to degrade
wastes to a fixed carbon ash residue and a gas component. The objective of
the process is to convert waste material from a disposal problem to a
gaseous fuel source. Pyrolysis systems cannot handle wastes that have a
high sodium content. The high temperature fluid wall is well suited for the
treatment of contaminated soil, but the material must first be ground,
dried, and reduced to a free-flowing solid with a particle size of approxi-
mately 100 mesh. The technology is therefore impractical for the treatment
of large quantities of contaminated sediments. Supercritical water, advanced
electric reactors, and vertical tube reactors are also in the development
stage.
Liquid injection incineration is designed for the combustion of liquid
organic wastes such as PCBs, solvents, still and reactor bottoms, polymer
wastes, and pesticides. Wastes high in metals and moisture content are not
suitable for treatment using this process. The multiple hearth incinerator
is widely used to incinerate sewage sludge but is also capable of handling
all forms of combustible waste materials, including sludges, tars, solids,
liquids, and gases. It is not suitable, however, for the incineration of
materials with a high ash content such as soils and sediments.
Fluidized beds are typically used for the disposal of municipal
wastewater treatment plant sludge, oil refinery waste, and pulp and paper
mill waste. It is well suited for incineration of wastes with high ash and
moisture contents, and may be considered for the remediation of contaminated
dredged material.
The rotary kiln is an applicable incineration technology for the
treatment of sediments contaminated with organic materials. It is the most
versatile of the incineration technologies because it can handle wastes in
any physical form. Rotary kiln incineration is the method of choice for the
thermal treatment of mixed hazardous solid residues, is the most frequently
chosen system for commercial offsite operations, and has been used for the
destruction of hazardous organic constituents in soils. Mobile incineration
units are available for onsite destruction of hazardous materials.
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Infrared incineration systems use electric heating elements instead of
combustible fuels to bring waste material to combustion temperatures. Pilot
experience using this approach has demonstrated the applicability of infrared
systems to the remediation of sludge materials (Shirco Infared Systems, Inc.
1987). The following factors must be addressed in considering the selection
of incineration technologies to treat dredged sediments from the Commencement
Bay N/T study area:
• Effects of inorganic constituents on refraction material
• Sediment pretreatment requirements (e.g., dewatering)
• Temporary storage of dredged sediments prior to incineration
• Site selection (i.e., onsite or offsite) and associated
transportation costs
• Particulate emission controls to reduce metals releases
• Characterization of ash and determination of disposal method.
Physical Treatment--
Physical approaches to treatment of contaminated dredged material and
associated dredge water result in the isolation and in some cases the
concentration of contaminants in a waste stream. The two primary categories
of applicable physical treatment technologies are phase separation and
partitioning processes. Phase separation approaches include filtration,
sedimentation, and dewatering. Solids fractionation is also considered here
as a volume reduction step. Partitioning processes include solvent
extraction and sorption.
Fi1tration--FiItration is the process whereby relatively low concentra-
tions of suspended solids are removed from an aqueous stream by forcing the
liquid through a porous medium. Particulate matter is retained on the
medium. Filtration is unlikely to be necessary for management of contami-
nated dredge water unless a treatment sensitive to suspended solids concen-
trations (e.g., ion exchange, carbon adsorption) is required. Removal of
the majority of suspended material from dredge water is best accomplished by
sedimentation followed by chemical coagulation.
Sedimentation—Sedimentation is the removal of suspended particulate
matter from a slurry or aqueous suspension by gravity settling. In the
context of contaminated dredged material management and disposal, especially
following hydraulic dredging, sedimentation is likely to be an integral
component of the overall remediation scheme. The U.S. Army Corps of
Engineers has evaluated sedimentation followed by chemical coagulation, with
the sedimentation basin also serving as the ultimate confinement area
(Schroeder 1983). In this approach, removal of dredge water from con-
taminated dredged material deposited at a nearshore or upland site is
followed by capping and closure procedures.
3-17
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Solids Fractionation--Separation of granular material into particle
size fractions has potential for reducing the volume of contaminated solids
requiring treatment when the contaminants of concern are associated with a
discrete and separable fraction of the solid medium. Equipment for
industrial solids fractionation applications includes screens and sieves,
hydraulic and spiral classifiers, cyclones, and settling basins.
In general, particle fractionation schemes for the treatment of
contaminated dredged material are conceptual and site-specific in potential
applicability. The efficiency with which the contaminated fraction can be
separated from the relatively uncontaminated material is critical to the
success of the process. A pilot-scale demonstration of particle fraction-
ation has been attempted in the Netherlands (Cullinane, J., 18 November
1987, personal communication) to recover material suitable for construction
work. The sediment was incidentally contaminated. Contaminants were
concentrated in the fines but the coarse material still contained residual
contamination.
Solids fractionation is unlikely to be an appropriate technology for
reducing the large volume of contaminated material dredged from Commencement
Bay problem areas. Sediments in the area are typically fine-grained, which
limits the suitability of solids fractionation technology. Bench-scale
treatability tests and pilot demonstrations would be required before
implementation on a field scale could be considered.
Dewaterinq--Dewaterina reduces the moisture content of contaminated
dredged material beyond what can be accomplished by gravity settling in a
sedimentation basin. Numerous mechanical dewatering devices have been
developed for industrial applications but have not been widely applied to
dewater dredged material (Yoshino et al. 1985). For the dewatering of
contaminated dredged material intended for upland confinement, incorporation
of an underdrainage system into the sedimentation basin disposal facility is
probably the most suitable approach (U.S. Army Corps of Engineers 1986c).
The underdrainage system would operate by gravity or be vacuum-assisted.
Treatment of water obtained from the dewatering of contaminated dredged
material must be considered in the event that contaminant concentrations
exceed acceptable values.
Solvent Extraction—Solvent extraction to remove organic contaminants
is under consideration at the New Bedford CERCLA site and a Hudson River
project (Austin, D., 22 January 1988, personal communication). In both
cases, PCBs are the primary contaminants of concern. In both instances, the
levels of PCB contamination are several orders of magnitude higher than
those observed in the Commencement Bay problem area. The specific technology
being evaluated is the BEST™ process marketed by Resources Conservation
Company.
The process involves using a solvent such as triethylamine (TEA), which
has the unusual property of being completely miscible in water at approxi-
mately 50° F but immiscible at temperatures near 100° F. It has a low
boiling point and heat of vaporization, which is favorable from an energy
3-18
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standpoint. The solvent is mixed with solid waste at the lower temperature
to extract organic contaminants and water into the liquid phase. The liquid
is warmed to effect the phase transition whereupon aqueous and organic phases
are separated. Residual TEA is recovered from the treated solids in a
drying step. The aqueous phase has low contaminant concentrations and,
because TEA is not a regulated hazardous constituent, can generally be
discharged without further treatment. Evaporative concentration of the TEA
solution and recovery of the solvent completes the process. Alkaline
conditions in the process can lead to precipitation of metals as hydroxides,
which remain in the treated solids. If the metals concentrations are not of
concern, it is plausible to consider returning the treated solids to the
marine environment. System capacities of over 500 ton/day are believed to
be feasible (Austin, D., 22 January 1988, personal communication).
Sorption—Removal of organic contaminants from aqueous wastes by
granular activated carbon adsorption is a proven and effective technology.
For contaminated dredged material management and disposal, carbon adsorption
may be appropriate for the treatment of contaminated dredge water. Although
the technology is best suited to the removal of organic contaminants, metals
such as arsenic, antimony, and mercury can also be removed to some extent.
To prevent clogging, the suspended solids concentration needs to be reduced
to less than 50 mg/L by treatment such as filtration or sedimentation. A
carbon treatment system will be used to remove PCBs from contaminated dredge
water during pilot dredging studies scheduled for the New Bedford CERCLA site
(Cullinane, J., 8 January 1988, personal communication).
3.1.6 Disposal Options
Remedial alternatives that involve a dredging component necessarily
include disposal in an aquatic, nearshore, or upland environment. In all
three cases, the deposited material can be confined or unconfined. Uncon-
fined disposal is generally inappropriate for Commencement Bay sediments
requiring remediation because of environmental and human health concerns.
Unconfined disposal is conceivable, however, for treated dredged material.
The various confined disposal options that are potentially applicable to the
Commencement Bay study area are reviewed below. Details are described in
Phillips et al. (1985).
Confined Aquatic Disposal--
The variations of the confined aquatic disposal option are depicted in
Figure 3-2. The open-water mound involves no lateral confinement structures,
and is the least protective confined aquatic disposal alternative. Dredged
material is transported to a location above the disposal site and discharged
by a split-hulled barge or through a vertical pipeline diffuser. Clean cap
material is then placed on the mound, using either discharge method in order
to achieve an appropriate cap thickness. The U.S. Army Corps of Engineers
(1986b) has identified a thickness of approximately 3 ft as appropriate for
most contaminated dredged material. Lack of precision in obtaining an
adequate cap thickness may require significantly more material than
theoretically required. Contaminant loss is limited to diffusion through
3-19
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WATER SURFACE
DEPTH OF STORM
WAVE INFLUENCE
SOLUBLE
DIFFUSION
CONVECTION
CONVECTION
aiOTURBATION
SOLUBLE
OWFUSION
CONVECTION
••EXISTING
' BOTTOM
A. OPEN-WATER MOUND
C. SHALLOW-WATER CONFINED
u>
I
ro
o
60-500. FT
DEPTH OF STORM
WAVE INFLUENCE
SOLUBLE
DIFFUSION.
CONVECTION
8IOTURBATION
CONTAMINATED
SEDIMENTS
<^
J-FT CAP OF-
CLEAN SEDIMENTS
" NATURAL '6* "•
; E»CAVATED
DEPRESSION
SOLUBLE
DIFFUSION.
CONVECTION
UNDERWATER
DIKE • .
B. OPEN-WATER CONFINED
D. WATERWAY CONFINED
Reference: Phillips el al. (1985).
Figure 3-2. Confined aquatic disposal of contaminated dredged material.
-------
the cap as long as the cap thickness is sufficient to mitigate the effects
of bioturbation or mechanical disturbances.
The open-water confined option depicted in Figure 3-2 is more protec-
tive than the mound in that an artificial or natural depression in conjunc-
tion with diking provides lateral confinement. Disposal of contaminated
dredged material in an open-water confined aquatic facility is proposed for
the Everett Harbor Carrier Battle Group Homeport program. For that project,
it is proposed that contaminated sediment will be dredged using a clamshell,
transported to the disposal site in a split-hulled barge, and dumped.
Precision positioning equipment will be used to ensure that contaminated
dredged material is placed within the target disposal zone. The disposal
site is sloped and will have a containment dike constructed along the lower
boundary. Depth to the disposal site is approximately 250-350 ft. The cap
material will be hydraulically placed using a diffuser positioned at a depth
of 60 ft below the water surface.
Confined aquatic disposal of contaminated dredged material has been
implemented at several sites, including Long Island Sound, the New York
Bight, and Rotterdam Harbor (the Netherlands). The contaminants associated
with those sediments included primarily inorganics, petroleum hydrocarbons,
and PCBs. Although limited data on disposal site conditions and capping
material were collected prior to disposal, subsequent performance monitoring
indicates that confined aquatic disposal has been effective in isolating
contaminated sediments (U.S. Army Corps of Engineers 1988).
Shallow-water disposal sites as depicted in Figure 3-2 are within the
influence of storm waves but are below intertidal depths (-10 to -60 ft
MLLW). Structural considerations are the same as for open-water confinement,
except the cap is thicker to accommodate the energetics associated with the
shallower depths. The level of control over placement of dredged material,
berm, and cap materials is greater than for the open-water alternative.
Waterway confinement as presented in Figure 3-2 is a variation in
which a pit, excavated in a relatively shallow (15-50 ft) navigable waterway,
receives both contaminated dredged material and cap materials. The hydraulic
energy associated with the quiescent waterways in the Commencement Bay
problem area is lower than that in other shallow-water environments exposed
to more direct wave action. However, propeller wash and ship scour would be
expected to increase subsurface energy significantly in the shallow waterway
environment. The volumetric requirements for disposal must account for
placement of the entire volume of contaminated dredged material, with an
appropriate bulking factor applied. Depending on dredging and placement
techniques, bulking factors of up to 100 percent must be applied. The
development of a single, open excavation of that size is not practical
within a waterway primarily because of logistics, such as temporary storage
of a large quantity of contaminated dredged material following the initial
excavation. Instead, the confined aquatic disposal site would be configured
to contain the required volume in a series of smaller cells or possibly
parallel trenches. If possible, the disposal site should be located in an
area that will not be dredged. In waterways requiring periodic dredging,
the contaminated dredged material and cap would need to be placed deep enough
3-21
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to preclude damage from the dredging. This approach to confined aquatic
disposal has not been field-tested although it is being considered for the
New Bedford Harbor Project.
Confined Nearshore Disposal--
Design features specific to confined nearshore disposal sites are
illustrated in Figure 3-3. Nearshore disposal locations are within areas
subject to tidal fluctuations (U.S. Army Corps of Engineers 1986c). Dredged
material is added to the diked area until the final elevation is above the
high tide elevation, and a cap 3-6 ft thick is installed. Nearshore disposal
sites are normally used in conjunction with hydraulic dredges. However, at
the Pier 90/91 nearshore fill in Elliott Bay (Seattle, WA), mechanically
dredged sediment was deposited at the disposal site, using a split-hulled
barge.
Disposal of contaminated marine sediments has occurred in several
nearshore facilities throughout the country. Approximately 90,000 yd3 of
sediments contaminated with heavy metals, PAH compounds, and PCBs was
disposed of at the Elliott Bay Pier 90/91 site in 1986. Monitoring conducted
following disposal has revealed that the contaminated material has been
effectively confined. Although there appears to have been some mobilization
of inorganic contaminants, it is unclear if the material originated from
within the confinement structure or from the material used to construct the
dike and cover (Hotchkiss, D., 20 April 1988, personal communication).
Approximately 20 nearshore disposal sites have been constructed in the Great
Lakes to confine dredged materials deemed unsuitable for open-water disposal
(U.S. Army Corps of Engineers 1987). However, limited analyses of con-
taminated sediments were conducted prior to disposal in these facilities,
which compromises the assessment of facility performance.
Depending on placement, physicochemical conditions in nearshore
facilities can be similar to those observed in both confined aquatic and
confined upland disposal sites. Subtidal portions of the fill remain
saturated and anoxic, which can aid in maintaining constant physicochemical
conditions to reduce contaminant migration potential. This condition
minimizes the potential for migration of metal contaminants. The fill zone
above tidal influences eventually drains and becomes upland in nature.
Within the tidal zone, tidal pumping may increase the likelihood of
contaminant migration by contributing oxygen and providing a convectiye
component for dispersion. Depending on the site-specific geohydrologic
features, groundwater may influence the hydraulics within a nearshore fill
unless barriers and liners are incorporated. Contaminant releases are less
amenable to control than is possible with upland confinement. However,
dredging, transport, and disposal technologies use well-established
equipment and methods to aid in effective implementation with minimal public
health or environmental hazards.
Confined Upland Disposal--
Design features and environmental exposure pathways specific to confined
upland disposal are illustrated in Figure 3-4. Upland disposal involves the
3-22
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UPLAND
VOLATILIZATION PRECIPITATION
A
UNSATURATED^ DREDGED
SATURATED-^ MATERIAL
CONVECTION
VIA TIDAL
PUMPING
NEARSHORE DISPOSAL
Figure 3-3. Confined nearshore disposal of contaminated
dredged material.
3-23
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UPLAND DISPOSAL
VOLATILIZATION PRECIPITATION
EXISTING
UPLAND
b CROSS SECTION
INFLUENT
PONDING
DEPTH
. FREEBOARD
AREA FOR SEDIMENTATION
COARSE-GRAINED
DREDGED MATERIAL
AREA FOR FINE-GRAINED
DREDGED MATERIAL STORAGE
EFFLUENT
Figure 3-4. Confined upland disposal (a) and components of
a typical diked upland disposal site (b).
3-24
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placement of dredged material in environments that are not inundated by
tidal waters. Upland disposal sites are normally diked and capped to
confine the dredged solids while allowing the dredge water to be released.
Upland disposal sites are most often associated with hydraulically dredged
sediments pumped to the upland site via pipeline. The transport of
contaminated dredged material following dewatering to upland disposal sites
by truck is possible for relatively short distances. Transportation of
large quantities of contaminated dredged material over a longer distance or
through congested traffic areas could pose a potential environmental hazard
and is not economical.
Relative to other listed options, upland disposal poses the greatest
potential risk to groundwater supplies, but also allows for greater control
of contaminated wastes through design features, improved monitoring
capabilities, backup contaminant interception, and treatment facilities.
Prior to placement in a landfill, it is likely that both dewatering and
stabilization of contaminated sediment would be required. If the dredged
sediment were classified as a hazardous waste, which is unlikely, disposal of
untreated contaminated dredged material in a RCRA-approved landfill would be
necessary. Compliance with all applicable hazardous waste handling and
transport regulations would be required for sediment classified as hazardous
waste. Problem sediments that do not violate established standards and
criteria for hazardous waste classification would require handling in
accordance with other appropriate environmental statutes. Relatively more
flexibility and options are available for handling problem sediments not
classified as hazardous waste. Intermixing of hazardous with nonhazardous
sediments should be avoided to reduce the volume requiring special treatment
and the associated transportation costs.
Both new and existing landfill facilities could receive dredged,
dewatered, and stabilized sediments. The design of the facility would
depend on the characteristics and final classification of the fill material.
Appropriate technical considerations would have to include options for
control and possibly treatment of effluent from dewatering process.
New RCRA landfills are subject to especially stringent criteria
regarding design, management, and the nature of wastes that may be handled.
Important design requirements include the following:
• A liner system to prevent leachate migration beyond the waste
containment zone
• A leachate removal and collection system
• A stormwater run-on management system
• A stormwater runoff management system
• A groundwater monitoring system.
3-25
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Disposal Site Availability--
Potential sites identified by Phillips et al. (1985) for the disposal
of contaminated Commencement Bay sediments are shown in Figure 3-5. The
sites were identified in a preliminary effort to locate potential disposal
facilities. This effort was not directed toward compiling the definitive
list of all possible disposal sites in the area. Potential capacities, and
land ownership information for each site identified is listed in Table 3-1.
The following discussion is a review of each site, with emphasis on
availability for contaminated dredged material disposal.
Open-Water Sites—Three open-water disposal sites are shown in
Figure 3-5. The Washington Department of Natural Resources (WDNR) site has
been designated for unconfined disposal of dredged material since 1972 and
has regularly received material since that time. Closure of the WDNR site is
expected in June 1988.
The Puyallup River delta site, owned by the State of Washington until
1972, was designated for unconfined open-water disposal. The site is
characterized by sloping topography, which has led to slides of sediment
mass into deeper waters (Phillips et al. 1985). Capping would therefore be
inappropriate under these circumstances. It may be possible to conduct
confined aquatic disposal operations in the deeper waters near the edge of
the slide zone, where any further sliding activity would increase cap
thickness. However, disposal operations would occur in the path of salmonid
migration to and from the Puyallup River system. Additional studies need to
be conducted to clarify the technical and institutional feasibility of using
this site for disposal. Currently, the Puyallup River delta site must be
considered unavailable.
The Hylebos/Brown's Point location has no history of disposal activi-
ties. It is characterized as a natural horseshoe-shaped depression which
could be closed off on the fourth side bv creating a dike. Estimated
capacity of the depression is 2.5 million yd*. The depth of the site ranges
between 100 and 200 ft (Phillips et al. 1985). Because the site has
previously not been used for disposal purposes, the existing benthic
community is largely undisturbed. However, the water surface in the area
has been used extensively for log booming which may have impacted the
benthic community. Because this site contains sufficient capacity for a
large volume of material and appears to be topographically suited to capping
operations, this site is considered for confined aquatic disposal of
Commencement Bay problem area sediments. Hydrological, geotechnical, and
environmental investigations of the site would be required prior to use.
Although there are no sites that are considered immediately available,
the potential exists for designating an area in Commencement Bay as an open-
water confined aquatic disposal site. The waterway confined aquatic
disposal option is generally implementable and sites should be available in
the Commencement Bay waterways. Confined aquatic disposal out of the
waterways may be preferable to the in-waterway option because of the
possibility that the waterways will be deepened in the future to accommodate
large shipping vessels.
3-26
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COMMENCEMENT BAY
Figure 3:5. Potential Commencement Bay disposal sites
identified by Phillips et al. (1985).
-------
TABLE 3-1. POTENTIAL SITES FOR CONTAMINATED DREDGED MATERIAL DISPOSAL3
Site
Capacity
Ownership
OPEN-WATER DISPOSAL SITES
Puyallup River Delta Site
WDNR Disposal Site
Approximately 900 ft
in diameter with up
to 170 ft in depth
Approximately 900 ft
in diameter down to
500 ft in depth
Hylebos/Brown's Point Site 2.5M yd3
UPLAND SITES
Puyallup Mitigation Site
Port of Tacoma Site "D"
Puyallup River/Railroad
site
Port of Tacoma Site "E"
Hylebos Creek Site No. 1
Hylebos Creek Site No. 2
NEARSHORE SITE
Middle Waterway Site
Milwaukee Waterway Site
40 ac
l.OM yd3
60 ac
1.55M yd3
80 ac
3.3M yd3
71 ac ,
1.7M yd3
25 ac
0.45M yd3
20 ac
0.325M yd3
27 ac
0.65M yd3,
(0.39M yd3 wet,
0.26M yd3 dry)
30 ac
2.16M yd3
(0.29M yd3 wet,
1.87M yd3 dry)
State of Washington
State of Washington
State of Washington
Port of Tacoma
Port of Tacoma
Union Pacific Railroad
Port of Tacoma
City of Tacoma
Multiple ownership
Multiple ownership
Land users/owners
include:
Foss Towing
Paxport Mills
Union Pacific R.R.
St. Regis Paper Co.
and others
Waterway owned by
State of Washington
Port of Tacoma
3-28
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TABLE 3-1 (Continued)
Capacity
Ownership
Blair Waterway Slips
Blair Creek Dock Site
Hylebos Waterway No. 1
Outer slip: 0.892M yd3
(0.825M yd3 wet,
0.067M yd3 dry)
Middle slip: 8 ac
0.945M yd3
(0.868M yd3 wet,
0.077M yd3 dry)
Inner slip: 12 ac
0.60M yd3
(0.484M yd3 wet,
0.116M yd3 dry)
700 ft x 500 ft
0.2M yd3
(0.136M yd3 wet,
0.064M yd3 dry)
74 ac
1.274M yd3
(0.550M yd3 wet,
0.724M yd3 dry)
Reference: Phillips et al. (1985).
State of Washington
Port of Tacoma
Port of Tacoma
Port of Tacoma
Port of Tacoma
Hylebos Waterway No. 2
24 ac
0.30M yd3
(0.07M yd3 wet,
0.23M yd3 dry)
Sound Refining Co.
(owned by
Chrysen Corp.)
3-29
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Sites--Hv1ebos sites #1 and #2 are subtidal and intertidal
areas. Both are environmentally sensitive and would therefore be difficult
to develop in terms of both technical and regulatory considerations.
Extensive mitigation measures would be required to develop these sites.
Chrysen Corp., owner of Sound Refining which borders the Hylebos #2 site,
has expressed interest in filling the area to expand operations but has been
opposed by tribal groups and Ecology (Mori, R., 13 January 1988, personal
communication).
Two of the three slips in Blair Waterway initially identified as
potential disposal sites are no longer under consideration. The outer slip
has been used as a fish habitat mitigation site, and the inner slip has been
filled as part of a Terminal 3 expansion project (Carter, S., 11 January
1988, personal communication). The middle slip (Slip 1) originally
designated as a potential nearshore facility remains as a potential disposal
site. This slip covers an area of approximately 8 ac and has an average
elevation of approximately -37 ft MLLW (Phillips et al. 1985). The total
capacity of this facility as a disposal site has been estimated at
approximately 900,000 yd3-
The Port of Tacoma plans to fill Milwaukee Waterway with essentially
uncontaminated sediments from Blair Waterway in order to expand port-related
operations (Sacha, L., 16 November 1987, personal communication). It is
possible that Commencement Bay problem sediments would be acceptable for
disposal in Milwaukee Waterway if proposed future uses of the site were not
compromised.
Although Middle Waterway is not maintained for channel depth by the
U.S. Army Corps of Engineers, shoreline businesses use medium draft vessels
in the waterway. It is shallow along its entire length, with an average
elevation of -7 MLLW. Little information is available on the suitability of
any part of this waterway for disposal of contaminated dredged material.
The Port of Tacoma is assessing the suitability of the Blair graving
dock site as a disposal site for sediments dredged from Sitcum Waterway as
part of a pier extension project. The graving dock site is estimated to
have a volume of 100,000 yd3 (Sacha, L., 9 May 1988, personal communication).
This site is considered potentially available for disposal of dredged
materials.
The only potentially available nearshore disposal sites within the
Commencement Bay waterway system that can receive contaminated dredged
materials are Blair Waterway Slip 1, Milwaukee Waterway, and the Blair
graving dock. The Port of Tacoma is reluctant to accept contaminated
dredged material in Milwaukee Waterway. Additional evaluation is needed to
explore the feasibility of Middle Waterway as a nearshore site. Hylebos
sites #1 and #2 appear to be unacceptable for use as disposal sites because
of wetland habitat considerations.
Upland Sites—The Puyallup mitigation site is a wetland area that is
protected from development. Port of Tacoma Site D has been developed into a
3-30
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foreign trade zone and is therefore no longer eligible for consideration as
a disposal site. The only municipal landfill identified for disposal of
treated dredged material is the Coal Creek landfill in King County. However,
disposal at Coal Creek is not considered feasible because of the required
transport distance (approximately 50 mi), and traffic impacts associated
with hauling large volumes of material).
RCRA Facilities—Two RCRA landfills operate in U.S. EPA Region X. Chem-
Security Systems, Inc. (CSSI) operates a minimum technical standards
landfill under interim permit status at its Arlington, OR facility.
Envirosafe Services of Idaho operates a facility near Grandview, ID, which
is also under interim status. Neither firm currently has a stabilization
capability. Because the Commencement Bay problem area is subject to the
CERCLA regulatory framework, onsite stabilization could be performed prior
to shipment to either of these facilities. Offsite RCRA landfill ing should
be considered as a reserve option only, in keeping with Section 121(b) of
CERCLA, which discourages the offsite transport and disposal of untreated
hazardous substances or contaminated materials.
Transportation--
Several methods are available in Puget Sound to transport sediments from
the Commencement Bay study area. The most practical method will be dictated
by the dredging method and access to the disposal site. Sediments removed by
hydraulic dredge can most efficiently be transported by pipeline to a
nearshore, upland, or aquatic disposal site if-distances between the dredge
and disposal sites are only a few miles. Sediments removed by clamshell
dredge will have nearly in situ densities. Such sediments can be transported
by split-hulled barge to nearshore and aquatic disposal sites and by truck
to upland disposal sites.
3.1.7 Summary of Preliminary Screening of Sediment Remedial Technologies
General response actions, technology types, and process options that
passed preliminary screening are illustrated in Figure 3-6. All six
general response actions identified initially remain applicable to sediment
remediation in Commencement Bay. In situ solidification/stabilization
processes are considered to be at a conceptual level of development for the
treatment of contaminated sediments, and are therefore not explicitly
represented during the development of remedial alternatives. They are
instead retained as a possible process option to be used in conjunction with
in situ containment.
3.2 SOURCE CONTROLS
Contamination in Commencement Bay sediments is the result of industrial
activities, waste disposal practices, and surface water management practices.
Efforts to reduce or eliminate further introduction of contaminants from the
various sources is essential to the overall sediment remedial effort.
Remedial technologies potentially applicable to source control are presented
in this section. This discussion of source control technologies is not
comprehensive and is intended to provided guidance for future studies
3-31
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GENERAL
RESPONSE ACTION
TECHNOLOGY TYPES
PROCESS OPTIONS
Use Restriction
Access Restriction [
Monitoring |
Hazard Education Programs)
Capping
Mechanical Dredging I
Hydraulic Dredging ]-
—| Specially Dredging I
Sediment ] Clay/Sand/Gravel
c:fc*e*bfarw::;:|:l Sorbents
Clamshell
1 Cutterhead
£| Suction I
{Mud Cat I Cleanup I Refresher | DREX | Waterless |
IN SITU
TREATMENT
POST-REMOVAL
I Solidification/Stabilization I
Chemical Treatment |
| Biological Treatment \-
——j Thermal Treatment |-
—| PhysJcaJTreatment |
DISPOSAL
Unconfined
Confined
Sorbents
| Grouts | Gets { VJirfcaiioB
Poz^olanic Processes Sealants
ton Exchange
Preapilalion
ComposunQ
Landtarming
Rotary Kiln ['' Mu«»tft H»ytt>
FlukjizedBed | Infrared [ MteC>
DewatBring Solvent Extraction Filtration
Sorption
Solids Fracbonation
Sedimentation
Open Water
Aquatic | Nearshore | Upland
Remedial technology or process option
sllmlnated In preliminary screening.
Figure 3-6. Potential sediment remedial technologies and process
options that are retained for further evaluation.
3-32
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focusing on specific sources. Information for the technology discussions was
drawn from U.S. EPA (1984, 1985a,b, 1986a,b, 1987), Wilson et al. (1986),
Rich and Cherry (1987), and Schueler (1987). The four general sources
discussed here are groundwater, surface water, soil, and air.
3.2.1 Groundwater
Past hydrogeologic investigations in the Commencement Bay N/T study
area indicate that three distinct aquifers underlie the vicinity (AWARE
1981). Groundwater reportedly occurs under water table conditions in the
surficial aquifer, and under confined conditions in two deeper aquifers.
Previous studies suggest that the prevailing hydraulic head differential
tends to concentrate contaminants from surficial sources in the 25- to 50-ft
depth horizon. Downward migration of pollutants is prevented below this
elevation by upward pressures in the deeper zones (Walker Wells 1980b).
Upward and downward groundwater pressure-gradient effects have also been
attributed to the controlling influence of tidal fluctuations in Commencement
Bay. During low tides, Commencement Bay seawater exerts minimal back
pressure on the aquifer system, and water table gradients steepen toward the
bay and adjacent waterways. During high tides, the maximum back pressure is
exerted and the water table rises, forcing groundwater flow landward. The
surficial aquifer in the vicinity of the study area is regarded as brackish
with specific conductivity values ranging up to 19,400 umhos/cm.
Although the hydrogeologic characteristics of the area have not been
thoroughly characterized, some hydraulic variables of the shallow ground-
water in the study area have been measured. Flow velocities have been found
to range from 4.9 ft/day at low tide to 0.4 ft/day at high tide (Hart-
Crowser & Associates 1983). Hydraulic gradients have been measured in the
range of 0.001 to 0.011 ft/ft, with a general average of approximately 0.005
ft/ft (Hart-Crowser & Associates 1983). The specific yield of the surficial
aquifer has been calculated at 0.2, with a coefficient of permeability of
approximately 50 gal/day/ft2 (Walker Wells 1980b).
Institutional Controls--
Institutional controls are nonstructural measures to mitigate the
public health and environmental impacts associated with contaminated
groundwater in the Commencement Bay study area. Restrictions on access or
use of contaminated groundwater would be considered as institutional
controls. Institutional controls are also available for preventing the
contamination of surface water which would (see Section 3.2.2) affect the
potential for groundwater contamination.
Containment--
Containment technologies prevent uncontaminated groundwater and
infiltrating surface water from contacting contaminated areas (for a dis-
cussion of surface water diversions see Section 3.2.2). Lateral and
downgradient movement of a contaminated plume can also be restricted by
these technologies, which include caps, vertical barriers, horizontal
barriers, and gradient controls.
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Canninci--Surface sealing or capping is intended to prevent infiltration
of surface water. Infiltrating surface water may transport contaminants
into groundwater by mobilizing them from soil, buried sludges, slag, or
landfills. Paving is the most common surface sealing or capping method
currently used in the Commencement Bay area. Cement, clay, native soil, a
synthetic membrane, or a combination of these materials may be used.
Flexible synthetic liner materials currently in use consist of polyvinyl
chloride (PVC), chlorinated polyethylene, ethylene propylene rubber, butyl
rubber, neoprene, and elasticized polyolefin (U.S. EPA 1985d). The
effectiveness of a cap in reducing permeability varies, depending on cap
material and construction methods selected. Because the Commencement Bay
area is characterized by a relatively shallow water table, some type of
barrier may be required in combination with a cap to prevent contact of
groundwater with contaminated soils.
Surface caps are usually designed to conform to performance standards
of RCRA landfill closure requirements. These standards include minimum
liquid migration through the wastes, low cover-maintenance requirements,
effective site drainage, resistance to loss of structural integrity (e.g.,
from subsidence), chemical stability, and a permeability lower than or equal
to the underlying liner system or natural soils (U.S. EPA 1985d). Multi-
layered caps are often required to meet the above standards for performance.
Prior to capping, soils may also be treated with lime or nonhazardous ash to
provide cementing properties, optimize grain size distribution, and reduce
shrink/swell behavior.
Vertical Barriers—Vertical barriers are subsurface cutoff walls or
diversions that contain, capture, or redirect lateral groundwater flow in the
vicinity of a contaminated site (U.S. EPA 1985d). Slurry walls are the most
commonly used barriers, followed by sheet piling, and grout curtains.
Slurry walls provide a relatively inexpensive means of reducing or
redirecting groundwater flow in unconsolidated materials. The wall extends
vertically from the ground surface to an impervious zone below the con-
taminated aquifer. The most common slurry is a mixture of soil, bentonite,
and water. Slurry walls offer low installation costs, a wide range of
chemical compatibilities, and low permeabilities (U.S. EPA 1985d).
Soil/bentonite slurries may be incompatible with strong acids and bases,
strong salt solutions, and some organic chemicals, which may restrict its
use in the Commencement Bay area. This mixture also exhibits the highest
compressibility, and hence the least strength, and is restricted to sites
that can be graded to nearly level because of its relatively low viscosity
compared with other slurries. A cement/bentonite mixture, made up of
Portland cement, bentonite, and water, can also be used. This slurry sets
up into a semirigid solid and can accommodate variations in topography. The
cement/bentonite slurry is less elastic (stiffer) but more susceptible to
fracture and more permeable than the soil/bentonite mix. Cement/bentonite
mixtures are susceptible to attack by sulfates, strong acids and bases, and
highly ionic substances (U.S. EPA 1985d).
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Sheet piling can also be used to form a groundwater barrier. Because
of cost and unpredictable integrity, sheet piling is used primarily for
temporary dewatering or erosion protection. Sheet piles can be made of
wood, precast concrete, or steel. Steel is generally considered to be the
most effective in terms of efficiency and cost (U.S. EPA 1985d).
Grout curtains are formed around a zone of contamination by injecting a
grouting mixture into well borings. These borings are usually arranged in a
pattern of two or three adjacent rows in order to extend the curtain width.
The fluid is injected under pressure, filling voids within the subsurface
material, and reducing the hydraulic permeability of the material as it
hardens. Grout curtains should be extended to an impermeable layer for
maximum effectiveness. Compatibility of grouting material with the waste is
essential. Grout curtain technology is not applicable for very fine-grained
or permeable soil conditions, or for situations where heterogeneous geologic
conditions exist.
Horizontal Barriers—Horizontal barriers are constructed beneath zones
of contamination and are intended to control the vertical flow of con-
taminated groundwater, redirect uncontaminated groundwater, or lower the
water table within an isolated area. Two approaches to formation of
horizontal barriers are grout injection and block displacement. Both
methods are in the development stage (U.S. EPA 1987). Grout injection
consists of drilling a series of holes across a site and injecting grout at
the base of the borings to form a horizontal or curved barrier.
Block displacement is an extension of grout injection technology and
involves complete isolation of a large earthen mass or block of earth by
means of a subsurface physical barrier (U.S. EPA 1983a). The barrier system
comprises a vertical perimeter and a horizontal bottom barrier. The vertical
component is constructed using one of the conventional techniques described
above. The bottom barrier is initiated by creating horizontal notches at
the base of two or more injection borings followed by the pumping of a
slurry mixture into the injection zone. Injection of the slurry continues
under pressure, with propagation of the notches eventually resulting in a
single separation zone. As water drains from the perimeter and bottom
barriers, a low permeability cake or grout is formed, which effectively
isolates the block of earth from surrounding strata. Block displacement
technology is not fully developed.
Neither grout injection nor block displacement is suitable for
heterogeneous or unconsolidated conditions. For waste site remediation,
grouting technologies are most appropriate for sealing voids or fractures in
rock formations (U.S. EPA 1985d). No documented applications of bottom
sealing or bottom barrier techniques to hazardous waste sites have been
reported (U.S. EPA 1985d).
Gradient Control--Groundwater levels may be manipulated to redirect
subsurface flow by using various drain or well systems. In shallow aqui-
fers, subsurface collection trenches and drains immediately downgradient of
the contaminated groundwater can be used to route the contaminated flow
towards a predetermined collection point for subsequent remediation.
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Upgradient interception trenches can be used to capture and redirect
unaffected groundwater, thus reducing the volume of contaminated groundwater
requiring collection or treatment. Gravel drains, perforated pipe drains,
or dual media drains may be used, depending on site-specific conditions and
requirements.
Extraction wells, in combination with injection wells where hydraulic
conductivities are moderate, can also be used to alter gradients. Extrac-
tion and injection wells are often used in combination with subsurface
barriers to control groundwater movement by reducing or increasing flow.
Local hydrogeology should be thoroughly characterized before designing and
implementing controls involving extraction and injection wells. Special
design considerations are required for semiconfined aquifers, such as the
secondary aquifer in the Commencement Bay study area in which contamination
has been documented.
Collection--
Contaminated groundwater may be actively collected for subsequent
treatment by pumping, or passively collected in subsurface drains.
Groundwater Pumpinq--Groundwater pumping techniques described above for
gradient control may be used to collect groundwater for treatment and
disposal. Clean water injected under pressure may help flush contaminants
from the subsurface materials into the groundwater, in addition to directing
flow towards the extraction wells. This technology is limited by the
chemical and physical properties of the contaminants and the aquifer. The
types of wells used in groundwater monitoring and pumping systems include
well points, suction wells, injector wells, and deep wells. Caution must be
exercised to avoid saltwater intrusion into nonsaline groundwater systems in
the Commencement Bay vicinity.
Subsurface Drains—Subsurface drains can also be used to collect
groundwater. Contaminated groundwater can be collected downgradient for
treatment, or clean groundwater can be collected upgradient. Upgradient
drains and flow barriers can be used to divert flow away from the con-
taminated zone and the downgradient collection system to reduce treatment
volumes. Typically these drains are not feasible for collecting groundwater
at depths greater than 50 ft because of construction difficulties. In the
project area, drains are potentially applicable to problems at log sorting
yards (if shallow groundwater is determined to be contaminated) and waste
burial locations (if underlying groundwater is protected by an impermeable
layer). Subsurface drains are generally more cost-effective than other
groundwater collection methods (e.g., pumping) if contamination is confined
to the upper aquifer.
In Situ Treatment--
In situ treatment techniques are receiving increased attention for the
remediation of water table aquifer systems contaminated with organics (Wilson
et al. 1986). Biological treatment approaches are based on the stimulation
of indigenous microbial populations that are physiologically capable of
3-36
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degrading a variety of organic contaminants. Augmentation of natural
populations with genetically altered organisms or with bacteria that
selectively degrade target compounds remains unproven technologically.
Physical/chemical methods of in situ groundwater treatment have not been
demonstrated for remediation of contaminated aquifers. Approaches to bio-
logical in situ treatment typically include groundwater pumping, above-
surface treatment, nutrient and oxygen enrichment of treated water, and
reinjection to the contaminated aquifer.
Pumping in conjunction with physical barrier systems serve to control
and contain the contaminant plume. Above-surface treatment may include a
sequence of process steps to remove metals and volatile organics. Possible
process options are similar to those discussed for contaminated dredge water
in Section 3.1.5. Nutrients such as nitrogen and phosphorus may be added
to the treated water as needed. If air stripping is one of the treatment
steps, further oxygen enrichment is generally not needed. Otherwise, a
separate oxygenation step may be considered. This step can be accomplished
using either air or elemental oxygen, or through the addition of a dilute
stream of hydrogen peroxide. The prepared water is then channeled to an
infiltration zone for recharge of the contaminated aquifer. Direct injection
of air or oxygen into the aquifer may be considered as an alternative or
additional aeration measure.
Post-Removal Treatment--
Treatment is generally required for groundwater extracted by a col-
lection program. Numerous physical, biological, and chemical treatment
processes are available to remove contaminants from aqueous wastes. Many of
the methods are widely used in municipal and industrial waste treatment, and
their effectiveness and limitations are well known. Treatment methods
applicable to a surficial aquifer in the project area must include the
impacts of brackish water that may be present. Saline groundwater has been
successfully treated in the past. However, a complete chemical charac-
terization must be conducted to provide a thorough understanding of the
chemical matrix subject to treatment.
Biological Treatment—Technologies for the treatment of contaminated
groundwater using above-surface biological systems have been demonstrated
(Nyers, E., 11 November 1987, personal communication). However, most
conventional approaches using trickling filter, activated sludge, and
rotating biological contactor technology are not suitable for the special
requirements of groundwater treatment systems. These systems must be
designed to operate under variable feed conditions and at much lower
substrate concentrations than conventional systems are capable of handling.
Compounds that are readily biodegraded include alcohols, phenols, carbonyl
compounds, and a variety of petroleum hydrocarbons. Chlorinated compounds
are generally not suitable for biological treatment. High metals concen-
trations can adversely affect biological systems. At least one operational
system is treating contaminated groundwater with a total dissolved solids
concentration of 15,000 ppm, and seawater salinities of around 30,000 ppm
are not believed to present a problem for biological treatment (Nyers, E.,
11 November 1987, personal communication).
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Physical Treatment—Physical treatment involves the following methods
to remove contaminants: phase separation, sedimentation, coagulation and
flocculation, filtration, air or gas stripping, distillation, ultrafiltra-
tion, reverse osmosis, carbon adsorption, and resin adsorption. Phase
separation takes place in a settling tank where liquids of different
densities separate into discrete layers. Oil and other floating products
are collected by a skimmer for subsequent handling. Chemical additives may,
be used to enhance separation.
Sedimentation and settling processes involve the sinking of suspended
particulates, which may have adsorbed contaminants. For certain contami-
nants, addition of a chemical flocculating agent to the liquid enhances the
aggregation of suspended particles, which can then settle by gravity. This
method is used to separate suspended colloidal particles from a liquid. In
liquids below pH 7.5, arsenic, cadmium, and chromium can be removed by
precipitation processes (U.S. EPA 1986a). For organic compounds, which form
organometallic complexes (U.S. EPA 1985d), cyanide, and other ions interfere
with precipitation.
Filtration separates particles suspended in groundwater by forcing the
liquid through a porous filter medium. Trapped particles form a cake which
can be periodically removed as necessary, and the filter can be regenerated
by backwashing.
Ultrafiltration removes solutes with high molecular weights by using a
semi permeable membrane under a low pressure gradient. Reverse osmosis
involves filtering contaminated water through a semi permeable membrane at a
pressure greater than the osmotic pressure caused by the dissolved materials
in the water. Because membrane surfaces are susceptible to clogging,
influent suspended solids concentrations must be fairly low. Both are
emerging technologies (U.S. EPA 1987). Ultrafiltration will be adversely
affected by the salinity of the dredge water from Commencement Bay.
Air and gas stripping may also be effective in remediating groundwater
contaminated with volatile organic contaminants. Air stripping is frequently
accomplished in a packed tower system with an air blower. Generally,
components with Henry's Law constants of greater than 0.003 can be effec-
tively removed by air stripping. Stripping is often only partially
effective and may be followed by another treatment process such as carbon
adsorption (U.S. EPA 1985d). Carbon adsorption may also be used to remove
organics in the air stream prior to discharge.
Carbon adsorption methods can be used to remove many organic con-
taminants (e.g., chlorinated hydrocarbons, phenols, aromatics). Per unit
volume, activated carbon has a large surface area onto which contaminants
can be adsorbed. Compounds with low water solubility, high molecular
weight, low polarity, and low degree of ionization are most effectively
removed by carbon adsorption. Some heavy metals (e.g., arsenic and chromium)
and some inorganic species have shown good to excellent adsorption potential
(U.S. EPA 1985d). Although saline solutions have little effect on the
system, high concentrations of inorganic salts and certain pH ranges cause
3-38
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scaling. Suspended solids concentrations greater than 50 mg/kg and oil and
grease concentrations greater than 10 mg/kg cause clogging and should be
removed by other means prior to carbon treatment (U.S. EPA 1987). Spent
carbon can be regenerated thermally. To minimize the expense and volume of
carbon, this treatment method is often used as one of the last steps in a
treatment scheme.
Solvent extraction allows recovery of certain dissolved contaminants
from groundwater by utilizing an immiscible liquid for which the components
have a high affinity. Solvent extraction in most cases requires the use of
other treatment processes (e.g., distillation or air stripping) to effec-
tively remove residual impurities before discharge. Several stages of
solvent extraction would be necessary for treating organic contaminants at
the Commencement Bay site. Application of solvent extraction to treat
groundwater is costly and would require pilot studies.
Chemical Treatment—Potential chemical treatment technologies appro-
priate for post-removal groundwater remedial action are identical to those
discussed in conjunction with treatment of contaminated dredge water
(Section 3.1.5).
Preliminary Screening of Groundwater Remedial Technologies--
The following technologies appear to have the greatest applicability to
contaminated groundwater in the study area:
• Capping
• Certain vertical barriers
• Gradient controls (e.g., pumping, subsurface drains) both to
contain and to collect groundwater
• Post-removal treatment, particularly by carbon adsorption and
ion exchange.
In all cases, the local hydrogeology and the chemical and physical charac-
teristics of the contaminated groundwater must be thoroughly understood.
3.2.2 Surface Water
Surface water in the Commencement Bay watershed can be contaminated
from specific point sources such as facility operations and from areawide
sources such as urban runoff. Although the strategy for implementation will
differ between the two kinds of sources, the same remedial technologies will
apply.
Methods of controlling contaminants in urban runoff are often called
best management practices (BMPs). These BMPs include measures of insti-
tutional control, containment and diversion technologies, and collection
techniques. The effectiveness of various technologies is highly variable
and depends on a number of factors, including the nature and extent of
3-39
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contamination in runoff, the sources of contamination, local topographic
features, and design considerations. Schueler (1987) compared the effective-
ness of various urban BMP designs and developed the results presented in
Figure 3-7. As shown in the figure, the different designs range in
effectiveness from 0 to 100 percent. Some BMPs believed to be appropriate
for the Commencement Bay study area are discussed in the following sections.
Treatment technologies are also discussed.
Institutional Controls--
Institutional controls involve nonstructural practices to reduce the
level of contamination in surface water runoff that reaches the waterways of
Commencement Bay. Both quantity and quality may be controlled by the
following kinds of management practices:
• Maintenance of existing drainage systems (e.g., regular
cleaning of oil/water separators)
• Street sweeping
• Soil management (e.g., revegetation)
• Public education
• Land use regulations.
Maintenance of Drain System—Proper maintenance of existing drainage
systems features designed to reduce runoff quantity and control quality is a
requirement for continued system efficiency. For example, oil/water
separators are typically placed in storm drain systems in areas with high
vehicle use (e.g., parking lots, maintenance areas, car wash facilities) to
remove floating oil and grease from the runoff prior to discharge. These
systems must be cleaned regularly to prevent oil and grease from being
resuspended and discharged during subsequent runoff events. Oil/water
separators would be applicable to many of the industrial sites in the study
area. The City of Tacoma is currently requiring the installation of
oil/water separators in drainage systems for automobile dealers, car washes,
and automobile detailers. Discharge from the separators will be routed to
the sanitary sewer system.
Street Sweeping—Street sweeping is a common method of removing dirt and
debris from city streets. Street sweeping reduces the amount of sediments
washed off street surfaces by storm water and, in theory, decreases suspended
solids and associated contaminant loadings in stormwater runoff. However,
investigations have found that street sweeping is not an effective means of
controlling contaminant loading because sweepers preferentially remove the
large-grained particles rather than the smaller particles, which adsorb most
of the contaminants (U.S. EPA 1983b). Modified street cleaners have also
been tested in an effort to reduce respirable fugitive dust emissions.
Modified street cleaners showed substantially better performance than
regular mechanical street cleaners in removing small particle sizes.
However, for the smallest particle size measured (<125 urn), inconsistent
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BMP/design
EXTENDED DETENTION 'OHO
DESIGN 1
DESION 3
DESIGN 3
WET POND
DESIGN 4
DESIGN 5
OIIIQN «
INFILTRATION TRENCH
DESIGN T
DESIGN 1
DESIGN t
INFILTRATION iASIN
OWION T
OSSION «
DESIGN *
POROUS PAVEMENT
DESIGN 7
DESIGN S
DESIGN S
WATER QUALITY INLET
DESIGN 10
FILTER STRIP
DESIGN 11
DESIGN 12
QRASSED SWALE
DESIGN 13
DESIGN 14
Design
Design
Design
Design
Design
Ldsign
Design
Des ign
Des ign
Design
Design
Design
Design
Design
1:
2:
3:
4:
5:
6:
7:
8.
.
9:
10:
11:
12:
13:
14:
• 0
• 3
• 9
• 3
9 3
• *
• 3
• 3
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• 3
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3 9
• 9
• 9
O ®
0 0
• 3
O O
O (3
(3 O 3 ® MODERATE
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339® Nia"
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O O O ® LO*
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O O O ® LO*
O O O ® "»»
First-flush runoff voluae detained for 6-12 hours.
Runoff volume produced by 1.0 inch, detained 24 hours.
As in Design 2, but with shallow *arsh in bottooi stage.
Permanent pool equal
Permanent pool equal
Permanent pool equal
Facility exfiltrates
Faci 1 i ty exf i 1 erects
Facility exfiltrates
400 cubic feet wet s
20 foot wide turf st
100 foot wide forest
High slope swales, w
Low gradient swales
to 0.5 inch storage per inpervious acre.
to 2.5 (Vr); where Vr^mean stora runoff.
to 4.0 (Vr); approx. 2 weeks retention.
first-flush; 0.5 inch runoff /i«per . acre.
all runoff, up to the 2 year design stons.
orage per iopervious acre.
ip-
d strip, with level spreader.
th no check dams .
ith check dams .
KEY:
O
O
3
9
0 TO 20% REMOVAL
20 TO 40% REMOVAL
40 TO (0% REMOVAL
• 0 TO 10% REMOVAL
SO TO 100% REMOVAL
INSUFFICIENT
KNOWLEDGE
Figure 3-7. Comparative pollutant removal of urban best
management practice (BMP) designs, as determined
by Schueler(1987).
3-41
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results were obtained for all street cleaners. Therefore, the effectiveness
of the technology is questionable (Pitt and Bissonnette 1984). The City of
Tacoma operates a street cleaning program, but its effectiveness in con-
trolling contaminants in surface runoff has not been evaluated.
Soil Management — Proper management of surface soils is required to
prevent excessive dispersion of sediment and associated contaminants in
runoff. Establishment of vegetative cover on barren areas helps to reduce
soil erosion. Revegetation is also used to stabilize the surface of
hazardous waste disposal sites and commonly functions as the upper layer in
multilayer capping systems. Revegetation may not be feasible at sites
exhibiting high concentrations of phytotoxic chemicals or poor moisture and
soil conditions. Therefore, in many cases, revegetation is preceded by
other remedial activities such as waste removal, grading, terracing, and
fertilization.
The basic elements in designing a revegetation program for soil
management include the following points:
• Selection of a suitable plant species
• Preparation of soil to maintain growing conditions (e.g.,
stabilization, grading, mulching, neutralization, ferti-
lization)
• Determination of optimum time for planting
• Maintenance (i.e., irrigation, fertilization).
Public Education Programs—Public education programs can be effective
in reducing the contaminant loading resulting from the improper disposal of
waste oils, solvents, and other household hazardous materials. Public
inattention to safe disposal practices can be addressed through well-timed
press releases, public service announcements, utility bill inserts, in-
formational pamphlets distributed at the point of purchase of household
chemicals, and programs within the local communities and public school
system. The City of Bellevue reported that increased public awareness
significantly reduced the dumping of wastes in catch basins and improved
neighborhood control of pet wastes and litter (Finnemore 1982). State- and
city-sponsored programs to collect hazardous wastes from the public may also
be effective in reducing the source of contaminants to the city storm drain
system.
The City of Tacoma has instituted a public awareness and education
program as part of an agreement with Ecology. The program has been developed
by the Tacoma-Pierce County Health Department and is targeted specifically
towards the Commencement Bay area of Tacoma. The major elements of the
program are as follows:
• Informational meetings with chamber of commerce and civic
groups
3-42
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• Distribution of informational pamphlets on household hazardous
wastes as inserts to utility bills
• Provision of information and guidance to business as part of
the inspection program initiated by the city sewer utility
• Cartoon coloring books for children.
The program is currently budgeted for the duration of the city storm drain
program (summer 1988). In addition Tacoma-Pierce County Health Department
is sponsoring a city- and county-wide household hazardous waste collection
day. The first collection day occurred on 26 September 1987 and is expected
to continue as an annual event (Pierce, D., 14 August 1987, personal com-
munication) .
Land Use Regulation — Implementation and enforcement of the following
examples of land use regulations can reduce inputs to the storm drainage
system:
• Onsite collection and treatment of stormwater runoff at new
residential, commercial, and industrial developments
• Erosion and sedimentation controls at construction sites.
Containment--
Containment technologies for surface water are designed to prevent gener-
ation of contaminated runoff by diverting clean water away from contaminated
areas, controlling erosion of exposed waste piles, or both. Run-on can be
prevented by structurally routing drainage away from the waste source (i.e.,
via surface diversions). Erosion of contaminated waste piles can be controlled
by revegetating, capping, or reshaping the land surface in question.
Surface Diversion—Surface diversion process options include dikes,
berms, diversion channels, floodwalls, terraces, and grading.
Dikes and berms are well-compacted earth embankments constructed around
the perimeter or immediately upslope of waste disposal areas to prevent
surface runoff from contacting contaminated soil zones. In addition, these
structures are widely used to provide temporary isolation of wastes and
surface runoff during removal or treatment operations. Flood control dikes
are designed to prevent surface water inundation of contaminated soil zones
during flooding events and therefore tend to be much larger structures than
dikes intended for stormwater management. U.S. Soil Conservation Service
standards describe three classifications of flood control dikes, based on
the level of protection required (Ehrenfeld and Bass 1983).
Open channels are conventional drainage structures which can be used at
hazardous waste sites for the collection and eventual containment of contami-
nated surface water or for transfer of diverted clean water away from zones
of contamination. Channel stabilization may be required, depending on bed
slope and whether use as a waterway is intended. Channels with parabolic
3-43
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cross sections are preferred for use at hazardous waste sites because they
cause less erosion than alternative configurations.
Land surfaces can be reshaped through grading, terracing, and bench
construction to control surface runoff and reduce erosion. Grading is rela-
tively inexpensive and can be used to either promote or reduce surface
runoff, depending on site conditions. Regrading to cause an increase in
surface runoff is typically used to prevent infiltration and thereby control
groundwater contamination at landfills and waste disposal sites, and is used
in conjunction with surface sealing and capping techniques. Landfill and
waste disposal site surfaces are graded to increase the slope so that most
of the rainfall runs off the surface rather than infiltrating through the
waste materials.
Reduction of surface runoff by regrading the land surface is an
effective means of controlling soil loss in areas where there are steep
slopes that accelerate erosion. However, because there is little surface
relief in most of the tideflat areas, grading is probably unnecessary.
Terraces and benches generally serve the same function by reducing slope
length.
The primary application of grading in the Commencement Bay study area
is recontouring the land surface to route surface runoff away from con-
taminated areas and to direct runoff to collection and treatment systems.
For example, one facility has combined surface grading with berm and curb
construction to collect runoff from the property and route it to the
facility's wastewater treatment plant (Parametrix 1987).
Reveoetation—This technology is discussed above.
Surface Capping and Sealing—Surface capping and sealing isolate buried
waste materials to prevent surface water runoff and rainfall from contacting
them. Although capping is typically considered a groundwater control
technology, it also provides surface water control. Other surface water
controls such as ditches, dikes, and grading are commonly used in conjunction
with capping to collect rainwater drainage from the capped area.
Collection--
Surface water may be collected for treatment or disposal by using the
same routing mechanisms described for containment (e.g., dikes, berms,
diversions channels, grading).
Treatment--
Discussions presented above for the physical, chemical, and biological
treatment of contaminated dredge water and groundwater are applicable to the
treatment of contaminated surface water. A special consideration in the
case of surface water is that the volumes of contaminated water collected are
likely to be very small in comparison to the volumes that would be generated
during groundwater and dredge water remedial efforts. This suggests that
batch treatment systems would be appropriate for consideration.
3-44
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Data from a number of studies conducted on the effectiveness of
detention and retention basins for treatment of stormwater runoff indicate
that removals of up to 75 percent total suspended solids, 99 percent lead,
98 percent zinc, 60 percent copper, 55 percent cadmium, and 50 percent nickel
are achievable (McCuen 1980; Whipple and Hunter 1981; and Horner and
Wonacott 1985). Studies on the effectiveness of grassy swales for removal
of particulates and metal contaminants in storm water have revealed that
removals of over 90 percent for iron and lead, 75 percent for copper, and
84 percent for zinc (Miller 1987). Removal efficiencies varied with nature
and duration of storm event, basin design, antecedent weather conditions, and
other factors.
Preliminary Screening of Surface Water Remedial Technologies--
The following technologies appear to have the greatest applicability for
controlling contamination carried in surface water runoff:
• Institutional controls (e.g., drain maintenance, revegetation,
erosion control), primarily applicable to reduce contamination
from ongoing inputs not related to contaminant reservoirs
onsite
• Capping
• Surface diversion to prevent or collect runoff
• Treatment of collected runoff.
3.2.3 Soil
Soil acts as a sink for immobile contaminants and as a reservoir or
conduit for more mobile contaminants. Groundwater quality may be affected
by surface water percolating through contaminated soil in the unsaturated
zone. Surface water may also become contaminated via direct contact with
contaminated soil. For this reason, soil control technologies include many
of those described for groundwater and surface water. Removal options
(e.g., excavating contaminated soil), which were not generally discussed as
source control technologies for other media, are relevant for contaminated
soil. In situ treatment is also more applicable to soil than to other media.
Institutional Controls--
Restricting access to contaminated areas may reduce public health
risks caused by inhalation, ingestion, or dermal contact with soil particu-
lates. Access restriction alone, however, does not reduce the potential for
migration of contaminants into groundwater and eventually offsite via
surface water or groundwater. Remediation of contaminated soils can be
conducted under federal, state, and local regulatory statutes.
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Containment--
Containment technologies applicable to soil include caps, vertical
barriers, horizontal barriers, revegetation, and surface diversion tech-
niques. These technologies are described in Sections 3.2.1, and 3.2.2.
Removal--
The removal of contaminated soils from hazardous waste sites is
accomplished using conventional earth moving equipment such as backhoes,
front end loaders, and bulldozers. Excavation plans generally include
provisions to minimize the amount of soil removed. After cleanup levels are
established, removal operations are conducted in several steps, each of
which is followed by sampling and analysis to determine the levels of
remaining contamination and the need for further excavation.
In Situ Treatment--
In situ treatment methods are most suitable for spills and plume-type
contamination where the contaminants are homogeneous and evenly distributed.
Some of the techniques may be limited to shallow areas (e.g., less than 2 ft
deep) or those lying above the water table (U.S. EPA 1984). More than one
technique may be needed if there is a diverse mixture of contaminants.
Stabi 1 i zati on/Sol idifi cation—Stabilization reduces the solubility or
chemical reactivity of waste by changing its chemical state or by physical
entrapment (microencapsulation). Solidification converts the waste into an
easily handled solid with reduced hazards from volatilization, leaching, or
spillage. Both stabilization and solidification improve the containment of
contaminants in treated wastes. Combined processes are often referred to as
encapsulation or fixation. Stabilization and solidification are discussed
in Section 3.1.5 for treating contaminated dredged material. Among various
technologies, lime-fly ash processes and pozzolan-Portland cement systems
are probably most feasible and relatively inexpensive for large volumes of
contaminated soil. Pozzolan solidified wastes are less stable and less
durable than pozzolan-Portland cement composites. Leaching losses from the
pozzolan-waste materials have been considered to be relatively high compared
with those for pozzolan-Portland cement waste materials. A number of
materials such as sodium borate, calcium sulfate, potassium bichromate,
chlorides, and carbohydrates will interfere with the binding reaction and
prevent bonding of materials. Oil and grease can also physically interfere
with bonding by coating waste particles. Both processes are considered
potentially viable for soil treatment.
Physical Treatment—Physical treatment techniques include heating,
attenuation, and reduction of volatilization. In situ heating methods use
steam injection or radio frequency heating to destroy or remove organic
contaminants. Because of their early stage of development, use of these
technologies in the Commencement Bay study area is currently not feasible.
Attenuation techniques involve mixing clean soil or other material with
the contaminated soil to reduce contaminant concentrations. The level of
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volatile emissions can be reduced in situ by reducing pore volume or by
cooling the soil. These same in situ techniques can be used to retain the
volatile contaminants for subsequent treatment.
Chemical Treatment—In situ chemical treatment methods for contaminated
soils are developmental or conceptual and have not been fully demonstrated
for hazardous waste site remediation (U.S. EPA 1985d). The single in situ
method that shows promise is solution mining, also referred to as soil
flushing. This technique has been used extensively by the chemical
processing and mining industries but has had limited application in the
treatment of hazardous wastes (U.S. EPA 1987). Solution mining involves the
injection of a solvent or aqueous solution, containing complexing agents,
into the soil. Following passage through the zone of contamination, this
solution is then collected at wells. Pilot tests for the decontamination of
soils containing PCBs and dioxins using chemical treatment have been
conducted by the U.S. EPA.
Biological Treatment—In situ treatment of organic contaminants by
biological organisms may be enhanced in several ways (see also Section
3.2.1). Activity of naturally occurring organisms can be enhanced by
adjusting soil moisture, oxygen content, pH, or nutrient content. Addition
of organic amendments (e.g., supplemental carbon or other energy sources) may
stimulate treatment of some xenobiotic compounds (U.S. EPA 1984). Artificial
enrichment analogs (compounds chemically similar to the hazardous compounds
of interest) can result in co-metabolism of the hazardous compound. For
example, biphenyl has been successfully used to stimulate co-metabolism of
PCBs (U.S. EPA 1984). Addition of exogenous organisms that have acclimated
to the contaminated soil (e.g., via mutation or genetic engineering) can
result in improved treatment, if their growing conditions are optimized
(U.S. EPA 1984). The addition of enzymes obtained from organisms able to
degrade hazardous wastes theoretically should accelerate degradation.
Post-Removal Soil Treatment—
Technologies discussed in Section 3.1.5 for sediments are also appli-
cable to the treatment of soils. In particular, thermal treatment for the
removal of organics and solidification to immobilize metals are proven soil
remediation technologies. For soils containing biodegradable organic
compounds and low concentrations of metals, land treatment is a viable
alternative. Solvent extraction using the BEST™ process is also potentially
viable for treatment of contaminated soil.
Preliminary Screening of Soil Remedial Technologies—
The following technologies appear to have the greatest applicability to
contaminated soils in the study area:
• Capping
• Certain vertical barriers
• Surface diversion of run-on and runoff
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• In situ treatment for well-characterized shallow contamination
• Removal
• Certain post-removal treatments.
Many of the technologies are used only for specific waste types (e.g.,
inorganic compounds, metals), whereas other technologies are nonspecific in
their action. The nonspecific technologies can alter the soil matrix
detrimentally for other uses.
3.2.4 Air
Air pollution resulting from contaminated sites in the study area is
not considered a major problem relative to the other media, particularly
since the ASARCO smelter has ceased operation. Air pollutants reach surface
water and sediments of Commencement Bay in two ways: by settling directly
on the water, and by settling on the land and then washing into the water-
ways. Stack emissions in the problem area are regulated by federal, state,
and local regulations in conjunction with PSAPCA.
Contamination of the air can result from gaseous emissions and fugitive
emissions. Gaseous emissions result from the vaporization of liquids,
venting of entrained gases (e.g., from tanks), and biological and chemical
reactions with solid and liquid waste material. Fugitive emissions include
windblown dusts from waste piles or surface soil, reentrained particulates
distributed by vehicles, and dusts generated during waste excavation.
Technologies for controlling airborne contaminants are described below for
gaseous and fugitive emissions. Containment, collection, removal, and
treatment technologies are integrated, as applicable, in the following
descriptions.
Gaseous Emissions--
Two primary methods of reducing gaseous emissions include covering the
evaporative surface to minimize exposure to the air, and installing an
active gas collection system. Covers can be used for both liquid and solid
wastes. Synthetic .material, such as plastics, can be used. For liquid
wastes in lagoons or other detention basis, covers can be made by floating
spheres or immiscible liquids on the surface.
Active interior gas collection and recovery systems change pressure
gradients and gas migration paths within the waste mass by mechanical
methods (e.g., pumps, compressors, blowers) and collect the gases in
extraction wells or headers. The gas must be treated after recovery.
Example treatment methods include adsorption, afterburning, and condensation.
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The following technologies are particularly applicable to reduce
gaseous emissions from impoundments:
• Increasing freeboard depth in holding tank and storage ponds
• Minimizing the surface area (e.g., by using deeper impound-
ments with smaller surface dimensions)
• Locating the inflow and outflow pipes to minimize turbulence
• Reducing influent temperature to the ambient temperature in
the impoundment
• Installing wind fences around the impoundment
• Minimizing disturbance from operations such as dredging
• Adding bulking agents to tie up the liquids and thereby
reduce emissions.
Fugitive Emissions--
Methods to reduce fugitive emissions include spraying dust suppressant
chemicals or water, erecting wind fences, and modifying the waste pile.
Particulate materials can also be removed physically, by sweeping and
vacuuming. Dust suppressants include resins, bituminous materials, polymers,
and water. If water is used, spraying must be performed often, on the order
of every 2 h (U.S. EPA 1985c). Vegetation can be used as a dust suppressant.
Porous wind screens can be erected to deflect or slow wind to speeds below
the threshold velocity for migration of the material. Vegetation can also
serve the same function.
Waste piles may be modified in several ways to reduce fugitive
emissions:
• Aggregate of larger diameter (e.g., large gravel) can be
spread on the surface to armor it against wind action
• The surface can be compacted mechanically
• The surface can be covered with a sheet of impervious or
porous material
• The slope angle and orientation to the wind can be modified
mechanically to reduce wind effects.
In operations that move contaminated materials, techniques that
minimize dust generation should be used. For example, an auger feed system
can be used instead of a clamshell bucket hauling system.
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Preliminary Screening of Air Remediation Technologies--
Approximately 6,000 tons of toxic air contaminants were released in
1986 from Pierce County (Puget Sound Air Pollution Control Agency 1987).
Roughly 75 percent of this was generated by nonpoint sources. The degree to
which these pollutants are returned to the terrestrial environment by either
wet or dry deposition processes is uncertain, but is believed to be
negligible in comparison with other sources of contamination. A determina-
tion of the significance of public health problems related to these releases
is not within the scope of this document.
3.3 DEVELOPMENT OF SEDIMENT REMEDIAL ALTERNATIVES
As discussed previously, sediment remedial technologies may be grouped
into one of six viable general response actions: no action, institutional
controls, containment, removal, treatment, and disposal. Each general
response action consists of one or more technology types and associated
process options. Sediment remedial alternatives are developed to define the
possible approaches to sediment remediation based on those general response
actions. The simplest sediment remedial alternative is no action; the most
complex alternative involves removal, treatment, and disposal technologies.
Costs and the level of permanency generally increase in progressing from no
action to alternatives involving sediment dredging and treatment.
A primary drawback of all operations requiring removal of contaminated
sediments or capping with clean fill material is the temporary destruction
of existing benthic communities and associated impacts on fish rearing
habitats. Past habitat management has frequently focused on replacing lost
intertidal or shoreline areas through the use of single, large, offsite
habitat projects. Recent efforts in urban embayment projects stress the
importance of improving habitats in existing intertidal and shoreline areas
(Demming, T., 18 April 1988, personal communication). Mitigation projects in
such areas should provide substrates that facilitate rapid recolonization of
benthic communities (e.g., incorporating large-grained, rocky material at
moderate slopes to maximize productive surface area). In this report,
remedial alternatives involving dredging of shoreline and intertidal
habitats include replacement of intertidal sediments to preremediation
elevations.
A list of the general response actions and representative technology
types that passed screening relative to sediment remediation is presented
below. These technologies are considered to have the greatest potential for
timely and effective remediation of contaminated Commencement Bay sediments.
• No Action
Accept current status
• Institutional Controls
Use/access restriction
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Monitoring
Education
• In Situ Containment
Capping
• Removal
Mechanical dredge
Hydraulic dredge
Specialty dredge
• Treatment
Solidification/stabi1ization
Chemical treatment
Physical treatment
Thermal treatment
Biological treatment
• Disposal
Unconfined
Confined.
3.3.1 No Action
There are no activities or technologies associated with implementing a
no-action approach to sediment contamination. This general response action
involves only the continuation of ongoing non-CERCLA/SARA permitting and
regulatory efforts for the potential contaminant sources within the project
area.
3.3.2 Institutional Controls
The viable technology types associated with this general category of
response are access restrictions, monitoring, and education. The first type
of technology involves actions that restrict access to contaminated sediments
as a method of preventing direct exposure (e.g., swimming, diving) or
indirect exposure (e.g., consumption of contaminated seafood). Monitoring
technologies are incorporated to ensure that restrictions are adequate and
appropriate. Education programs are included to provide a forum for
dissemination of public information regarding potential hazards and updates
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on restricted areas. Aggressive regulatory source control measures
specifically designed to address the remediation of contaminated Commencement
Bay N/T sediments are an integral component of the institutional controls
response action.
3.3.3 Containment
For in situ containment of sediments, capping is the only viable
technology. For implementation of capping, use of uncontaminated dredged
material for the cap was assumed, although the use of a different medium
could be considered in a more detailed analysis. In situ solidification
coupled with capping may be effective but was not evaluated because
subaquatic solidification of sediments is not a developed technology (see
Section 3.1.3). Aggressive pursuit of source control measures to facilitate
the sediment remediation process is also inherent in this response action.
3.3.4 Removal
Hydraulic and mechanical dredging represent the two fundamental
approaches to sediment removal. The pipeline cutterhead dredge is the most
commonly used hydraulic dredge in the U.S. and the Pacific Northwest (U.S.
Army Corps of Engineers 1985). Several modifications for the removal of
contaminated sediments with hydraulic dredges have been developed to improve
production capabilities and reduce dredging sediment resuspension (Phillips
et al. 1985). Although the pipeline cutterhead dredge was selected to
represent hydraulic dredging, specialty hydraulic dredges identified in the
preliminary screening of dredging technologies may warrant consideration
during final design and equipment selection, especially for dredging in
confined spaces or around existing structures. Aggressive pursuit of source
controls (i.e., as in institutional controls) is inherent in the removal
response action.
The clamshell dredge is the only mechanical dredge retained from the
preliminary screening. Although use of a watertight bucket modification was
assumed for development of alternatives involving mechanical dredging, a
conventional clamshell should also be considered when selecting equipment.
3.3.5 Treatment
Several sediment treatment technologies were selected for further
evaluation. Of the possible stabilization/solidification process options,
only sorbent stabilization, pozzolan/cement systems, and proprietary
stabilizing materials passed the preliminary screening. Pozzolan/cement
systems were identified as the representative process option because they
are the most protective from the standpoint of contaminant immobilization,
particularly when the sediments contain particle-associated organic
constituents. In some cases, however, stabilization rather than solidifi-
cation may be adequate for the reduction of contaminant mobility, and will
generally be less expensive. Proprietary stabilizing formulations should
also be evaluated during treatability studies to select the most suitable
stabilizing material. Aggressive pursuit of source controls (i.e., as in
institutional controls) in inherent in the treatment response action.
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Within the category of physical treatment, three process options were
selected for further evaluation as components of one or more sediment
remedial alternatives: solvent extraction using the BEST™ process,
sedimentation to remove suspended solids from dredge water, and dewaterirm
to further reduce the moisture content of dredged material. The BESTm
solvent extraction process is potentially applicable to the removal of
hazardous organic contaminants (e.g., PCBs, PAH, chlorinated hydrocarbons,
phenols). The process essentially concentrates the organics in liquid form,
which may then be incinerated or disposed of at much less expense than the
dredged material itself.
Sedimentation is essential for nearshore and upland disposal of
hydraulically dredged sediments. Chemical flocculation to remove solids
remaining in suspension following primary solids removal was assumed to be
included in the sedimentation process option. In this case, chemical
flocculation would involve the addition of a liquid polymeric flocculent to
the effluent from the primary containment and sedimentation area at the weir
structure. This process is shown schematically in Figure 3-8.
Dewatering methods, both passive and mechanical, are an essential
feature of upland disposal options when landfill requirements must be met.
Mechanical dewatering is not evaluated further here, but should be considered
in a more detailed evaluation of alternatives involving upland disposal,
especially for small volumes of dredged material. In the development of
sediment remedial alternatives, passive dewatering in the form of underdrains
provided in upland confinement systems was assumed.
Three thermal treatment systems were retained for further evaluation
an explicit following preliminary screening: rotary kiln, fluidized bed,
and infrared incineration systems. Infrared incineration was selected as
the most representative thermal treatment. Mobile systems with high
capacities are available, and they have been demonstrated to be effective in
treating contaminated soils and sludge-like materials.
No chemical treatment process options were selected for evaluation as
an explicit part of sediment remedial alternatives, because none were
identified as feasible for the treatment of dredged material solids.
Nonetheless, treatment of dredge water by sedimentation followed by
flocculation may be necessary to meet water quality criteria. Management of
dredge water produced during hydraulic dredging was assumed to involve
chemically assisted sedimentation. Mechanical dredging was assumed to
result in minimal production of dredge water and negligible treatment costs.
The severity of dredge water contamination is determined by the physical and
chemical properties of the contaminants and the degree to which they are
partitioned among particulate, aqueous, and gaseous phases. Many of the
problem contaminants in Commencement Bay sediments have strong particle
affinities and may be substantially removed by the sedimentation process
alone. Elutriate testing of Commencement Bay dredged material will be
necessary during the design phase to determine the need for dredge water
treatment.
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POLYMER FEED
SYSTEM
DREDGE
PIPE
SECONDARY
CONTAINMENT
AREA
PRIMARY
CONTAINMENT
AREA
DISCHARGE
CULVERT
Reference: Phillips et al. (1985).
Figure 3-8. Dredge water chemical clarification facility.
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3.3.6 Disposal
Disposal technologies include both unconfined and confined process
options. Confined aquatic, nearshore, and upland disposal are confined
process options. These three confined disposal process options passed
preliminary screening. Confined aquatic disposal options include waterway,
shallow-water, and open-water techniques using dikes and caps to isolate con-
taminants. Nearshore disposal options involve dike and cap construction
methods for contaminant containment within an intertidal environment.
Upland disposal options incorporate underdrains, liners, dikes, and caps to
isolate contaminants and control contaminant migration.
For the Commencement Bay N/T FS, long-term cleanup goals were set
based on the lowest AET value of the three biological indicators (see
Section 1.3.5). PSDDA guidelines for unconfined, open-water disposal use
two levels of chemical concentrations for dredged material evaluation. The
screening level defines the concentrations below which no adverse effects
would be expected at the disposal site. Conversely, the maximum level is
used to identify material that would be unacceptable for unconfined, open-
water disposal. Sediments exhibiting concentrations between the screening
and maximum levels are subjected to biological evaluation to determine
disposal status, similar to the process for refinement of volumes for
Commencement Bay N/T sediment remediation. Generally the FS target cleanup
goals fall between the PSDDA screening and maximum levels. A portion.of the
Commencement Bay problem sediments may meet PSDDA open-water disposal
guidelines. However, because of the impracticality of separating sediments
within a problem area that meet open-water guidelines from those that do
not, and because of the institutional considerations regarding liability of
Commencement Bay problem sediments, unconfined open-water disposal is not
considered as part of any remedial alternative. Unconfined open-water
disposal may be a feasible option for treated sediments when the level of
contamination has been reduced to below target cleanup goals or it has been
demonstrated that the potential for adverse biological effects has been
eliminated.
3.4 IDENTIFICATION OF CANDIDATE REMEDIAL ALTERNATIVES
The six general response actions and sediment remedial technology types
identified above were combined to form the set of ten candidate sediment
remedial alternatives presented below:
• No action
• Institutional controls
• In situ capping
• Removal/confined aquatic disposal
• Removal/nearshore disposal
• Removal/upland disposal
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• Removal/solidification/upland disposal
• Removal/incineration/upland disposal
• Removal/solvent extraction/upland disposal
• Removal/Iand treatment.
Each alternative represents a plausible combination of remedial actions for
the Commencement Bay sediment remediation effort. As a whole, the set
encompasses the range of general response actions and represents all viable
sediment remedial action technologies and process options. Implicit in each
of the identified sediment remedial alternatives, except no-action, is the
aggressive pursuit of source control measures under all existing environ-
mental authorities to reduce contaminant inputs to sediments to the maximum
extent possible, using all known, available, and reasonable technologies.
The level of achievable contaminant source control must be considered in
evaluating alternatives to assess long-term remediation effectiveness and
the potential for recreating adverse biological effects. This aspect of the
sediment remediation effort is addressed for each specific problem area in
Chapters 5-13. Each alternative is defined in more detail below.
3.4.1 No Action
The no-action alternative supplies a baseline against which other
sediment remedial alternatives can be compared. Under the no-action
alternative, the site would be left unchanged, with no remediation of
sediment contamination. This alternative does nothing to mitigate the
public health and environmental risks associated with the site, but its
evaluation is required by the National Contingency Plan. Absence of any
additional source control under the provisions of CERCLA/SARA regulations is
an implicit element of this alternative. Potential impacts of the no-action
alternative include the following:
• Continued potential for human health effects associated with
consumption of contaminated fish and shellfish
• Continued high incidence of fish disease (e.g., liver lesions)
• Continued bioaccumulation of problem chemicals in the aquatic
food chain
• Continued depressions of the benthic communities (reducing the
value of contaminated areas as habitat for fishery resources)
• Continued acute and chronic toxicity associated with
sediments.
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3.4.2 Institutional Controls
Institutional controls include access restrictions, limitations on
recreational use of nearshore areas, issuance of public health advisories,
monitoring, and most importantly, aggressive regulatory control of contami-
nant sources specifically oriented toward remediation of sediment contami-
nation. Limitations on access and recreation (e.g., fishing, diving) reduce
human exposure and risk to public health, but do nothing to mitigate the
existing environmental impacts mentioned under the no-action alternative.
Some degree of long-term mitigation is expected as a result of reductions in
source loadings. The effects of source control on contaminant loadings and
on natural recovery of sediments is discussed for each problem area in
Chapters 5-13. Monitoring is included in this alternative to permit
identification of contaminant migration patterns and assess sediment
recovery associated with source control. Monitoring would be designed to
allow assessment of changes in risks to public health and the environment
before impacts are realized.
3.4.3 In Situ Capping
In situ capping involves containment and isolation of contaminated
sediments through placement of clean material on top of existing substrates.
Implementation of the in situ capping alternative can only be initiated
following implementation of adequate source control measures to ensure that
sediment recontamination does not occur. The capping material may be clean
dredged material or fill (e.g., sand). In addition, it may be feasible to
include additives (e.g., bentonite) to reduce hydraulic permeability of the
cap or sorbents to inhibit contaminant migration. In situ capping can
substantially reduce the risks of environmental exposure to sediment
contaminants.
Both mechanical and hydraulic dredging equipment can be used for in
situ capping operations. Cohesive, mechanically dredged material would be
placed by using a split-hulled barge. Hydraulically dredged material would
be placed by using a downpipe and diffuser. Depending on site topography,
diking may be necessary along a margin of the capped sediments to provide
lateral cap support.
In situ capping as a sediment remedial alternative has the advantage of
preserving the original physicochemical conditions of the problem sediments.
This limits the potential for metals mobilization, which can result from
bringing predominantly anaerobic sediments into an aerobic environment
during dredge and disposal operations. Furthermore, contaminant redistri-
bution from resuspension of sediments during dredging is avoided. Therefore,
in situ capping provides a highly protective alternative for isolation of
contaminated sediments. The in situ capping alternative can be readily
implemented, with no obstacles associated with disposal facility siting.
Performance monitoring of capping operations in the shallow environments
typical of the Commencement Bay N/T problems areas uses well-established
sampling and analytical methods. In addition, construction and engineering
controls for in situ capping and diking operations can be easily implemented
in the shallow-water environment.
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Capping is inappropriate for environments with a high potential for
ship scour, currents, or wave action because these disturbances can lead to
cap erosion. Currents in the contaminated Commencement Bay waterways are
primarily tidal in origin and result in generally quiescent flow conditions.
The region along the Ruston-Pt. Defiance Shoreline has currents of sufficient
strength to be considered nondepositional in nature (i.e., subject to
erosion). Maintenance dredging precludes the use of capping in areas
maintained for shipping (e.g., Hylebos, City, and Sitcum Waterways).
For the purposes of evaluating the capping alternative and estimating
costs, it was assumed that clean dredged material from the Puyallup River
would be used to construct the cap. Although in situ capping has been
successfully conducted with hydraulic dredging equipment, for costing
purposes it was assumed that the capping material would be dredged using a
clamshell to maintain cohesiveness, transported to the problem areas and
deposited hydraulically to create a cap with a minimum thickness of 3 ft.
Evaluation during design may dictate placement of additional capping
material to prevent failure due to erosion or diffusion of mobile con-
taminants. Additional cap thickness or barrier layers may also need to be
included to mitigate the effects of deep burrowing species on cap integrity.
3.4.4 Removal/Confined Aquatic Disposal
As with in situ capping, implementation of the confined aquatic
disposal alternative requires that aggressive source control measures be
enacted to prevent recontamination of remediated areas. Confined aquatic
disposal can also substantially reduce environmental exposure to sediment
contaminants. In this alternative, contaminated sediment would be dredged
from one location, confined at a different aquatic location, and capped.
The several confined aquatic disposal options described in Section 2.0
differ from one another based largely on depth and physical characteristics
of the disposal site. Hydraulic or mechanical dredging followed by hydraulic
or split-hulled barge placement techniques can be used to implement this
alternative.
Four confined aquatic disposal approaches were described in Section
3.1.6. Of these, the open-water and waterway approaches appear to be the
most suitable for sediment remediation in Commencement Bay. Shallow-water
disposal sites have not been identified. Such sites are considered to be
less protective because of the proximity to the water surface and potential
for wave-induced erosion of the containment structure. Open-water disposal
siting is also somewhat uncertain, but potential sites have been identified
in Commencement Bay (Phillips et al. 1985). As compared to the in situ
capping alternative, additional time would be required prior to implementa-
tion to allow for siting and development of an open-water facility.
Placement of contaminated dredged material in an open-water disposal facility
followed by capping would effectively minimize the potential for contaminant
migration in that nearly in situ physicochemical conditions would be
maintained. In addition, the low energy environment of the facility would
help ensure cap stability and effectiveness and further aid in reducing the
potential for leaching of contaminants to adjacent substrates as compared to
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nearshore and upland disposal options. Implementation of the confined
aquatic disposal alternative in an open-water site would be complicated by
the difficulties associated with accurate placement of dredged material at
depths exceeding 75 ft. Monitoring and general maintenance activities at an
open-water disposal site are also complex and generally more costly than for
more accessible sites (e.g., nearshore or upland).
The waterway confined aquatic disposal option is feasible and has the
advantage of retaining the contaminated sediments within CERCLA site
boundaries. As envisioned for a contaminated Commencement Bay waterway, the
waterway alternative would involve minimum transport of sediments with
confinement of the dredged material within the waterway itself. This
approach would entail dredging an area well below the zone of contamination,
depositing contaminated dredged material in the excavated pit, and capping
it with clean dredged material. (See discussion in Appendix B.) This
approach has the disadvantage of requiring placement of a significant amount
of dredged material (some possibly contaminated) out of the waterway because
of bulking. The process also entails placement of a thick cap in areas
where post-remediation maintenance dredging is likely to occur. This form
of confined aquatic disposal was not considered because of uncertainty
regarding required maintenance depths for larger vessels. To accommodate
the potential for future dredging to -50 ft MLLW in the Commencement Bay
N/T area, excavation of excessive amounts of sediment would be required to
ensure isolation of contaminated material. The waterway confinement option
would also require interruption of waterway traffic for implementation of
the cellular approach to dredged material excavation and placement.
Use of an open-water disposal site was assumed for this feasibility
study. A clamshell dredge would be used to maintain nearly in situ densities.
Also, by minimizing water entrainment, a clamshell dredge would result in
easier transport and fewer or less severe water quality impacts. Dredged
materials would be transported to the disposal site and placed directly with
a split-hulled barge to limit bulking and water column impacts. Cap
materials would subsequently be placed in the disposal site using a submerged
diffuser system to minimize water column turbidity and facilitate more
accurate placement of materials. Use of the diffuser system would eliminate
upper water column impacts by radially dispersing the material parallel to
and just above the bottom at low velocity (Phillips et al. 1985).
3.4.5 Removal/Nearshore Disposal
Dredging followed by confined disposal in the nearshore environment is
another possible alternative for sediment remediation at the Commencement
Bay N/T site. As with the previous alternatives, an effective remediation
program incorporating nearshore disposal can only be conducted following
successful control of ongoing contaminant sources to the sediments.
Generally, nearshore sites need to be diked before they can receive dredged
material. There are essentially no limitations in the selection of dredging
and transport equipment, although hydraulic dredging followed by pipeline
transport to the disposal facility is considered optimal (Phillips et al.
1985). All variations considered for the removal/nearshore disposal option
utilize industry standard equipment and methods that are generally available.
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Implementation of the alternative can also proceed rapidly as a result of
the availability of the Blair Waterway site. Hydraulic dredging confines
dredged material to a pipeline during transport, thereby minimizing exposure
potential and handling requirements. Systems for management and treatment
of dredge water can be readily incorporated into the facility design. The
distances between several of the problem areas and the proposed Blair
Waterway nearshore disposal site are extensive. Mechanical dredging with a
clamshell system would be used for implementing this alternative in problem
areas greater than 2 mi distant from the disposal site. For problem areas
within 2 mi, a hydraulic dredging system would be .possible. Logistical
problems may be encountered, however, in areas with heavy marine traffic.
Compared to confined aquatic disposal, confined nearshore disposal
permits a greater degree of control in both the design, construction, and
maintenance of the confinement system. In addition, it is easier to monitor
for contaminant migration through the perimeter dike of a nearshore facility
than a large subaquatic cap. Because of the relatively gentle surface water
conditions typical of the Commencement Bay area, appropriate dike construc-
tion would be expected to control wave erosion of the confining materials.
The primary environmental impact associated with implementation of this
alternative is loss of existing benthic habitat at both the dredge and
disposal sites. Because of the intertidal location of the disposal site and
the high value placed on intertidal habitat, this alternative would require
a habitat mitigation component. Also, the influence of tides and groundwater
on contaminant transport would be much greater for nearshore confinement
than for confined aquatic or upland disposal. In addition, altered redox
conditions may increase the mobility of metals, depending upon the level of
placement within the disposal site. To the maximum extent practical,
sediments containing predominantly inorganic contaminants would be placed
below the water table level in the confinement facility to minimize
contaminant mobility.
For the purpose of evaluating this alternative, it was assumed that the
nearshore disposal facility in Blair Waterway would be utilized. A cutter-
head hydraulic dredge and pipeline transport system would be used for
problem areas close to the nearshore facility (e.g., Sitcum Waterway).
Because of the low solids content of hydraulically dredged sediments (15-25
percent solids by volume), management of dredge water would be required. In
this case, dredge water would be clarified to remove suspended solids prior
to discharge to the marine environment. A chemical coagulant addition
system and secondary settling basin similar to that described by Schroeder
(1983) would be included as an element of this remedial alternative where
hydraulic dredging is proposed. For those problem areas greater than 2 mi
distant from the disposal site or where use of a pipeline system is
logistically infeasible, a clamshell dredge would be used to excavate and
place dredged material in the nearshore facility. This is a conservative
costing approach. It may also be feasible to leave an access point in the
outer containment dike at the disposal site to facilitate placement of
dredged material using a split-hulled barge. This approach would require
placement of a barrier across the dike to contain suspended sediments
during the remediation process. It would also require that placement of
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dredged material be done sequentially within a reasonable time-frame from
waterways where nearshore disposal is to be used.
A schematic depicting general features of a nearshore disposal facility
is presented in Figure 3-3. To accommodate a dredge water control system
using chemical flocculation, the secondary settling basin would resemble that
illustrated in Figure 3-8. Other assumed design features include fill
depth of 30 ft and a minimum cap thickness of 3 ft. Additional capping
material may be required to facilitate subsequent construction over the
confinement facility. The facility was assumed to be unlined.
3.4.6 Removal/Upland Disposal
Dredging followed by upland disposal would involve the transfer of
dredged material to a confinement facility that is not under tidal influence.
Sediment could be dredged either mechanically or hydraulically and trans-
ferred to the disposal site by truck, rail, or pipeline. As in the case of
nearshore disposal, the alternative can be implemented using standard
dredging and transport equipment that is generally used for similar
operations. Provisions would be required for the management of dredge water
and leachate generated during the dewatering process. Implementation of
sediment remedial efforts would be contingent upon the successful control
and regulation of contaminant sources to the problem area in question.
Upland disposal would provide for the greatest level of contaminant
control in the absence of treatment. Design features would include a liner
and cap. The liner system would include an underdrainage for dewatering the
fill material and for controlling leachate over the long term. The under-
drainage would be designed to operate as either a passive collection system
or a vacuum-assisted dewatering system.
The primary environmental impact of this remedial alternative would be
destruction of existing benthic life at the dredging site. As with all
alternatives that involve dredging, resuspension of contaminated sediment
would also be a concern. Destruction of habitat at the upland disposal site
is likely to be less significant than at a nearshore site. Implementation
of this alternative would also involve risks to area groundwater resources
in the event of contaminant migration from the confinement facility.
Transport of contaminated dredged material to the upland facility would also
pose additional worker and public exposure hazards in the event of a system
failure or spill. Disposal in an upland facility would result in significant
physicochemical changes in dredged material which could increase mobility of
the metal contaminants.
For the purpose of evaluating this alternative, it was assumed that an
upland disposal site would be developed within 3 mi of the problem area.
Compared to the in situ capping and nearshore disposal alternatives,
additional time would be required prior to implementation to allow for
siting and development of an upland disposal facility. Dredging would
be conducted using a pipeline cutterhead dredge and material would be
hydraulically transported to the disposal site. Clamshell dredging could
also be conducted with upland disposal as the ultimate destination, but the
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requirement for double handling of the contaminated material (i.e., removal
to barge and then transfer to truck or railcar) would be a distinct disad-
vantage. A schematic of an upland confinement facility is presented in
Figure 3-3. Dredge water clarification (e.g., using the secondary settling
basin and chemical clarification design shown in Figure 3-8) would be an
essential feature of the facility. It was assumed that the disposal facility
would be constructed to contain contaminated dredged material to a depth of
15 ft. A dual synthetic liner and passive underdrainage system would be
included to permit removal of percolating dredge water and allow for long-
term leachate collection. Dredged material would settle and ponded dredge
water would be removed. Passive collection of percolating water would
continue until the fill had consolidated to an extent that allowed capping
operations to commence. The upland landfill would be lined with 4 ft of
clay and have an underdrain system. The cap would be 2 ft thick and
composed of clay.
3.4.7 Removal/Solidification/Upland Disposal
Solidification, as an option for treatment of contaminated dredged
material following implementation of source control measures, is considered
below in conjunction with clamshell dredging and upland disposal. Solidifi-
cation can significantly reduce the mobility of problem chemicals by
chemically immobilizing metals and encapsulating the particle-associated
organic compounds. A significant increase in volume may result from this
treatment option.
Treatment by solidification could be conducted at either nearshore or
upland disposal sites. Either hydraulic or mechanical dredging equipment
could be used to remove the contaminated sediment. In the former case,
sedimentation to remove most of the dredge water would be required prior to
blending in the solidification agents. However, some moisture (approxi-
mately 50 percent) is required for the hydration reaction required as part of
some solidification processes (Long, D., 12 April 1988, personal communi-
cation). As discussed in Section 3.1.5, several solidification agents and
implementation scenarios are feasible for this treatment option, although
none have been field-tested with marine sediments.
For the evaluation of this alternative, contaminated sediments were
assumed to be mechanically dredged and transported to the upland site.
Clamshell dredging has the disadvantage of requiring double handling of the
contaminated dredged material. However, solidification of material with a
relatively high solids content can result in a 10-15 percent treatment cost
reduction because of reduced reagent requirements. Dredged material would be
staged in hoppers and fed by a screw conveyor system for solidification.
Mixing would be completed in a treatment facility with in-line mixing of
solidification agents. Discharge would be either directly to the confinement
facility or to a truck for transport to the facility. Curing times for the
process may be extended as a result of the salt (e.g., chloride, magnesium)
content of the dredged material.
Design features for the disposal facility would depend on the hazard
level of the solidified sediment. In developing this alternative, it was
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assumed that the treated material would not be a RCRA hazardous waste and
that the confinement facility could be designed to satisfy minimum functional
standards for landfills in accordance with state regulations (WAC 173-304).
The liner would be 4 ft thick and composed of clay to meet a maximum
permeability standard of 1 x 10"' cm/sec. An underdrainage system atop the
clay liner would remove dredge water. The facility would accommodate a
15-ft fill depth and be capped with 2 ft of clay to meet a permeability
standard of 1 x 10~° cm/sec. Although it may be possible to return solidi-
fied sediments to the problem area of origin, this option has not been
field-tested for marine sediment. Extended curing times based on the salt
content of dredged material would be expected to complicate the process for
large volumes of sediments.
3.4.8 Removal/Incineration/Upland Disposal
Incineration permanently eliminates organic contamination in sediments.
This alternative has limited application in the Commencement Bay N/T because
most problem areas are characterized by significant metals contamination,
and because marine sediments are characterized by very low Btu content,
making incineration extremely energy-intensive and less cost-effective. As
for the other alternatives, aggressive pursuit of source control measures
was assumed.
For this alternative, sediments were assumed to be mechanically
dredged, using a watertight clamshell bucket to minimize water content of
the dredged material, minimize water column partitioning of contaminants, and
maintain in situ sediment densities. Wastes low in moisture content are
preferred for incineration because costs increase significantly as the
amount of water that must be driven off increases. If hydraulic dredging
were selected, an additional process step to settle and recover the solids
from the dredge slurry would be necessary. Even with clamshell dredging,
some dewatering may prove to be cost-effective.
The dredged material would be transported to shore by barge and then to
an upland site for incineration. It is possible that an incinerator could
be located adjacent to the problem area and transport by truck could be
avoided. Analysis of the incinerated residue may reveal that the material
no longer requires special handling and confinement. Open-water disposal
may be a feasible option for disposal of incinerated contaminated dredged
material, but in this alternative, disposal in a minimum security landfill
was assumed for evaluation.
3.4.9 Removal/Solvent Extraction/Upland Disposal
For sediments containing primarily organic contaminants, solvent
extraction followed by incineration of the organic concentrate would be a
feasible alternative. Depending on the concentration of metals in the
problem sediments, all disposal options may be considered. This approach to
sediment remediation would result in permanent removal and destruction of
organic compounds. Source control would be necessary to prevent recontamina-
tion.
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For the purpose of evaluating this alternative, use of the BEST™
technology marketed by Resources Conservation Company (Bellevue, WA) was
assumed. This process takes advantage of the inverse immiscibility
properties of aliphatic amines to separate organics from aqueous slurries of
contaminated material and from organic sludges. Effluents from the process
would include wastewater, treated solids, and a concentrated waste organic
mixture. Depending on the quality of the wastewater, additional treatment
may be required. Solids retain a low residual concentration of extracting
solvent and, depending on metals content, may be returned to the removal
site for unconfined disposal, placed in a PSDDA open-water disposal site, or
landfilled in a secure facility. The extracting solvent, typically
triethylamine, is not a listed hazardous waste constituent, which simplifies
waste solids and wastewater disposal.
It was assumed that contaminated sediments would be dredged using a
clamshell, transported via barge, and offloaded using a clamshell to an
onshore treatment facility. The contaminated dredged material would be
treated, dried, and transported to an upland disposal facility. Because the
process effectively dewaters the solids, stabilization was considered
unnecessary.
3.4.10 Removal/Land Treatment
For sediments contaminated with biodegradable organic compounds, a land
treatment option may be considered. Land treatment involves the incorpora-
tion of waste into the surface zone of soil, followed by management of the
treatment area to optimize degradation by natural soil microorganisms.
Chemical and physical characteristics of the waste need to be evaluated to
determine the amount that can safely be loaded onto the soil without
adversely impacting groundwater. Soils possess substantial cation exchange
capacity, which can effectively immobilize metals. Therefore, wastes
containing metals can be land-treated, but careful consideration of the
assimilative capacity of the soil for metals is essential.
For evaluating this alternative, it was assumed that sources would be
controlled and that sediments would be removed using a clamshell to minimize
water content of the dredged material. After transport by barge and truck
to the land treatment facility, the sediment material would be distributed
and tilled into the upper 15-30 cm of soil. The land treatment facility
design would prevent stormwater run-on and allow collection and management
of runoff. Lysimeters and monitoring wells would be installed and
periodically sampled to aid in the detection of subsurface contaminant
migration.
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4.0 DEVELOPMENT OF SEDIMENT REMEDIAL ACTION EVALUATION CRITERIA
A detailed analysis of the 10 candidate sediment remedial alternatives
and recommendation of the preferred alternative for each problem area is the
final stage of the feasibility study process. This section presents the
criteria used to analyze the alternatives. A narrative evaluation matrix
has been included in the problem area-specific sections to provide a summary
of the key considerations for each candidate alternative relative to each
criterion.
Evaluation criteria for the detailed analysis can be grouped into three
general categories: effectiveness, implementability, and cost. For the
Commencement Bay Nearshore/Tideflats (N/T) Feasibility Study (FS), there are
four effectiveness criteria: short-term protectiveness; timeliness; long-
term protect!veness; and reduction in contaminant toxicity, mobility, or
volume. The three implementability criteria comprise technical feasibility,
institutional feasibility, and availability of both equipment and disposal
facilities. (Other types of implementability criteria, such as coordination
among agencies and public acceptance, are more appropriately evaluated
during the development of a Record of Decision and are not discussed in this
document.) Cost elements include design and specification preparation,
capital construction, intertidal habitat replacement, operation and
maintenance (O&M), and monitoring.
The criteria specified in this section are consistent with the require-
ments of CERCLA/SARA and NCR. Final guidance has not been provided by
U.S. EPA on the procedures for evaluating remedial alternatives at Superfund
sites. However, categories of' criteria specified in CERCLA guidance
documents (e.g., U.S. EPA 1985e) were modified on an interim basis by
U.S. EPA (1986d) and Porter (1987) to include new requirements under SARA
[e.g., compliance with all applicable or relevant and appropriate require-
ments (ARARs) and preference for permanent solutions or treatments]. In
addition, the draft guidance document for conducting feasibility studies in
accordance with CERCLA/SARA, including the preferred alternative selection
process (U.S. EPA 1988a), has been incorporated into this report.
Effectiveness, implementability, and cost criteria are defined in
Sections 4.1, 4.2, and 4.3, respectively. Section 4.2 is substantially
longer than the other sections, primarily because the set of ARARs discussed
under institutional feasibility is large and complex. Section 4.4 presents
the framework for identifying the preferred sediment remedial alternative.
By definition, this alternative must effectively meet the objectives of the
Commencement Bay N/T sediment remediation effort and the intent of recent
guidance to provide solutions that are consistent with ARARs. The selection
process is complicated by technical and institutional uncertainties and by
tradeoffs among alternatives. The evaluations presented are based on the
best available information. The relative significance of these uncertainties
affects the final standing of the various alternatives; this factor is
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considered in the evaluations. The tradeoffs that emerge in comparing the
alternatives are also considered in the selection process. The final
selection and implementation of the preferred alternative for each problem
area may be modified to reflect refinements of the existing technological or
chemical database.
4.1 EFFECTIVENESS CRITERIA
The purpose of this section is to identify and define four effectiveness
criteria: short-term protectiveness; timeliness; long-term protectiveness;
and reduction in contaminant toxicity, mobility, or volume.
4.1.1 Short-Term Protectiveness
Short-term protectiveness is the predicted ability of the candidate
sediment remedial alternative to minimize public health and environmental
risks caused by exposure to contaminants during the implementation phase.
The analysis identifies potential hazards associated with implementation and
corresponding control measures. The evaluation of candidate sediment
remedial alternatives based on short-term protectiveness includes the
following considerations:
• Community protection during implementation - Potential public
health risks due to implementing the alternative, including
additional hazards due to the action itself. This evaluation
includes a general assessment of potential hazards to public
health associated with excavation, transfer/transport,
treatment, and disposal of the contaminated sediments.
Potential routes of exposure and targets are also considered.
• Worker protection during implementation - Potential occupa-
tional hazards due to implementing the alternative, including
hazards associated with exposure of sediments during
excavation, transfer/transport, treatment, and disposal.
This evaluation includes both physical and chemical hazards
associated with each process option, the degree of specialized
safety training required for implementation, and an informal
assessment of the potential hazards posed by a major worker
exposure incident.
• Environmental protection during implementation - Nature and
magnitude of potential environmental impacts associated with
implementing the alternative. This evaluation includes
identification of the environment at risk and review of the
potential impacts associated with system failures during
implementation.
4.1.2 Timeliness
Timeliness refers to the estimated time required for the candidate
alternative to meet remedial objectives (i.e., to effect mitigation and
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achieve results based on observed biological effects). This evaluation
includes an assessment of the time required for the following activities:
• Implement source controls integral to success of the alter-
native
• Demonstrate feasibility of unproven technologies
• Modify existing technologies to site-specific conditions
• Develop treatment or disposal facilities not currently in
existence
• Implement sediment remediation, including treatment and
disposal as necessary.
4.1.3 Long-Term Protectiveness
Long-term protect!veness is the predicted ability of the candidate
sediment remedial alternative to minimize potential hazards in both the
problem areas and the ultimate disposal sites after the objectives of the
alternative have been met. Effectiveness of the engineering and institu-
tional controls available to manage risk (U.S. EPA 1988a) are especially
important. This analysis includes an assessment of hazards associated with
disposal of untreated waste, disposal of residuals resulting from treatment
options, and potential failure of the technical components (e.g., containment
structures, treatment systems). The evaluation of candidate sediment
remedial alternatives based on evaluation of long-term protectiveness
includes the following considerations:
• Long-term reliability of containment facilities - Success in
remediating the observed adverse environmental effects and
in providing a final solution for the isolation, treatment,
and disposal of contaminated sediments. The analysis
estimates the magnitude and nature of the hazards due to
potential failure of the protective components of the system,
identifies the components most susceptible to failure, and
assesses the engineering and institutional controls required
to ensure system reliability. Population and environment at
risk are identified.
• Protection of public health - Long-term ability to reduce
public health hazards associated with the contaminated
sediments. This evaluation includes an assessment of how the
subject alternative achieves protection over time, how site
hazards are reduced, and how treatment or disposal processes
impact long-term health hazards. This evaluation requires
estimates of the feasibility of source control.
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• Protection of the environment - Potential long-term environ-
mental impacts associated with implementation, based on
system reliability and associated long-term hazards. This
evaluation includes identification of the environment and
media at risk and the potential sensitivity of the environment
to system failures (including failure to perform to prescribed
specifications). This evaluation also requires an assessment
of the effectiveness of system performance monitoring.
4.1.4 Reduction in Toxicitv. Mobility, or Volume
This criterion addresses the statutory preference (U.S. EPA 1988b) for
treatment vs. isolation (i.e., prevention of exposure). This analysis
requires that volume be addressed separately from toxicity or mobility
because some of the treatment or removal process options can increase
volumes (e.g., solidification, hydraulic dredging). For problem areas
containing mixed wastes (e.g., organic and inorganic contaminants), the
portion of the waste subject to treatment is delineated. The reduction in
the threat posed by the contaminants may be achieved through destruction of
toxic contaminants (e.g., incineration), reduction of the total mass of
toxic contaminants (e.g., chemical oxidation), irreversible reduction in
contaminant mobility (e.g., solidification), or reduction of total volume of
contaminants (e.g., solvent extraction). The degree to which treatment
processes are irreversible, the type and quantity of residuals remaining
following treatment, and the methods for managing residuals are considered.
The evaluation under this criterion focuses on the treatment processes
used and the contaminants they have been developed to address. The
estimated efficiency of the treatment process is considered based on the
problem chemicals present. The percentage reduction in toxicity, mobility,
or volume can only be quantified following the completion of bench-scale
testing of problem sediments. SARA revisions to CERCLA and recent U.S. EPA
guidance further suggest development of alternatives that use permanent
solutions, and alternative treatment technologies or resource recovery tech-
nologies to the maximum extent practicable. Based on the nature and
concentration of the contaminants in the sediments of the nine problem
areas, recovery of reusable resources is not expected to be practical.
4.2 IMPLEMENTABILITY CRITERIA
The purpose of this section is to identify and define three general
implementability criteria: technical feasibility, institutional feasibility,
and availability.
4.2.1 Technical Feasibility
Technical feasibility is the ability of the candidate sediment remedial
alternative to be fully implemented based on site-specific chemical and
physical features as well as general construction and engineering con-
straints. The evaluation of technical feasibility focuses on implementation,
maintenance, and monitoring, and includes the following considerations:
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• Feasibility and reliability of process options - Feasibility
of constructing the necessary components of the remedial
alternatives, and reliability of the corresponding process
options. This evaluation includes a qualitative estimate of
hazards due to system failure at any point in the remediation
process, and may include an evaluation of the effectiveness
of contingency plans. The ability of a technology to meet
specified process efficiencies or performance goals is also
considered.
• Implementation of monitoring programs - Ability to track
performance in meeting the remedial objectives. This
evaluation involves estimating confidence in early detection
of problems and identifying potential exposures (public
health and environment) caused by inability to detect system
failures. This evaluation also requires a determination of
whether migration pathways are sufficiently well defined to
be monitored adequately.
• Implementation of O&M programs - Feasibility and time
required to implement an O&M program to ensure the maximum
reliability and performance of the system.
4.2.2 Institutional Feasibility
Institutional feasibility is the ability of the candidate sediment
remedial alternative to meet the intent of all applicable criteria, regula-
tions, and permitting requirements. The evaluation of the candidate sediment
remedial alternatives based on institutional feasibility includes the
following considerations:
• Approval of relevant agencies - Feasibility of obtaining
necessary agency approvals, including time and activities
required. Although CERCLA actions are exempt from permit
requirements under SARA, this evaluation addresses the need
for, and feasibility of, obtaining concurrence from appro-
priate agencies on whether the candidate alternative will
meet the substantive aspects of the permit requirements.
The compliance of the subject alternative with advisories and
guidance for similar projects in similar environmental
settings is also considered.
• Compliance with applicable or relevant and appropriate
requirements (ARARs) - Compliance of the subject alternative
with the regulatory framework governing activities related to
the problem area-specific environmental setting, protection of
public health, and implementation of the remedial action and
associated process options.
The following detailed discussion is provided to identify ARARs that
must be considered in evaluating the alternatives. Additional details on
ARARs are presented in Appendix C.
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Compliance with ARARs--
The purpose of this section is to identify ARARs in terms of their
importance in assessing candidate alternatives. ARARs are critical in the
selection of appropriate remedies and will influence the implementation of
remedial alternatives in individual problem areas. Because several actions
such as dredging, dredge water management, and dredged material disposal are
common to more than one candidate alternative, the discussion is organized by
functional activity rather than remedial alternative, as follows:
• No action
• Institutional controls
• Dredging
• Treatment of contaminated sediments
• Disposal of sediments and treatment residues.
Section 121 (d)(2)(A) of CERCLA as amended by SARA incorporates the
CERCLA compliance policy. According to this policy, remedial actions must
meet promulgated requirements, criteria, or limitations that are legally
applicable or relevant and appropriate. The policy further states that
other standards, criteria, advisories, and guidance that may be useful in
developing remedies are to be considered, but not according to the formal
evaluation process required for ARARs. ARARs of federal and state government
and Indian tribes must be considered during CERCLA remedial action.
Although local ordinances are not specified as ARARs, they are considered in
the selection of alternatives.
Porter (1987) differentiates between requirements that are legally
applicable, and requirements that are relevant and appropriate:
• Legally applicable requirements consist of substantive
environmental protection requirements (e.g., standards for
cleanup or control) promulgated under federal, state, or
tribal law that specifically address a hazardous substance,
pollutant, contaminant, remedial action, location, or other
circumstance at a CERCLA site (e.g., drinking water standards,
air emissions criteria, or state hazardous waste regulations
that would be applicable at the site even if it were not being
addressed under CERCLA)
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applicable requirements that their use is well suited to-
particular site (e.g., design requirements for RCRA landfill
may be considered relevant and appropriate for a disposa
operation at the site even though it is under CERCLA, nc
i - - - ____ \ - - & • t *j i
may be considered relevant and appropriate for a disposal
operation at the site even though it is under CERCLA, not
RCRA, jurisdiction).
For remedial actions within the CERCLA site boundary, ARARs must be met
unless the requirements are waived pursuant to Sections 121 (d)(4)(a-f) of
CERCLA for one of the following reasons:
• The remedial action selected is only part of a total remedial
action that will attain compliance with ARARs
• Compliance with ARARs will result in greater risk to human
health or the environment than other alternative actions
• Compliance with ARARs is technically impractical
• The action will attain the equivalent of an ARAR through an
analogous process
• For state requirements, the state has not consistently applied
the ARAR in similar circumstances
• For CERCLA Section 104 actions, compliance with ARARs will
jeopardize the availability of fund money for other sites
(i.e., fund balancing).
If components of a candidate remedial alternative fall under the
jurisdiction of a given ARAR, that ARAR is deemed applicable. Jurisdictional
requirements include the following:
• Substances covered
• Time period covered
• Types of facilities covered
• Persons covered
• Actions covered
• Areas covered.
A requirement may be relevant and appropriate even if it is not
legally applicable. In general, a requirement can be considered relevant and
appropriate if the situation at the CERCLA site is sufficiently similar to a
problem that the requirement is designed to address. This determination
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relies heavily on professional judgment. The following factors are used to
compare the site conditions to the requirement in question:
• Similarity of goals and objectives of the requirement and the
remedial alternative
•• Environmental media and substances regulated and targeted for
remediation
• Action or activity regulated and considered for remediation
• Type of physical location, structure, and facility regulated
and considered for remediation
• Resource use or potential use.
Given the complexities of the general response actions under consider-
ation for the Commencement Bay N/T site, classification of a specific
environmental statute as applicable or relevant and appropriate will be
established in the Record of Decision and further refined in the remedial
design phase. However, the following discussion provides a format for
evaluating legislation likely to be most important in selecting a preferred
remedial action for the site.
Federal, state, and local permits are not required for the portion of
any removal or remedial action conducted entirely onsite, or for work
performed under CERCLA Sections 104 and 106. However, substantive (but not
procedural or administrative) requirements of permit applications may be
legally applicable or relevant and appropriate for onsite actions. Offsite
actions do not require an analysis of ARAR compliance. However, the
transfer of hazardous or contaminated material offsite is allowed only if
there is a facility operating in compliance with RCRA, TSCA, or other
applicable state and federal requirements. The purpose of this offsite
policy (U.S. EPA 1988b) is to ensure that disposal facilities are technically
sound so that CERCLA wastes do not contribute to present or future environ-
mental problems.
ARARs can be classified as chemical-specific, location-specific, or
action-specific.
Chemical-specific ARARs are health-based or risk-based concentrations
or ranges of concentrations in environmental media for specific chemicals.
Examples of chemical-specific ARARs are federal water quality criteria, air
quality standards (federal and state), and maximum contaminant levels [MCLs,
or MCL goals (MCLG)] set by the Safe Drinking Water Act (SDWA). If a
chemical has more than one ARAR, the most stringent value should be used.
Location-specific ARARs may set restrictions on remedial activities
based on the characteristics of the environment in the vicinity of the site.
Examples of location-specific ARARs include the Coastal Zone Management Act
(CZMA), Executive Orders for floodplain and wetland protection, state land
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use laws and regulations, and regulations to protect sites of archaeological
and historical value.
Action-specific ARARs may set restrictions based directly on the nature
of a remedial alternative. Examples of action-specific ARARs are RCRA
design and monitoring requirements for closure and post-closure of disposal
sites, and Clean Water Act requirements for dredging and dredged material
disposal.
Factors To Be Considered --
The CERCLA compliance policy specifies that other nonpromulgated or
interim standards, advisories, and guidance that may be useful in developing
remedial action alternatives are to be considered (TBC). TBC factors for
the Commencement Bay N/T remedial effort may include federal and state
policies, guidelines, and advisories; local ordinances such as City of Tacoma
shoreline and land use plans; PSDDA guidelines for the handling and disposal
of dredged material; and carcinogenic potency factors and reference doses
established by U.S. EPA for use in developing criteria such as MCLs. TBCs
can also be classified as chemical-specific, action-specific, or location-
specific.
Classification of ARARs and TBCs--
The remainder of this section is organized by type of ARAR or TBC (i.e.,
chemical-, location-, or action-specific). For each ARAR or TBC type, a
selected list of potential ARARs or TBCs is developed; and for each ARAR, a
preliminary classification (i.e., applicable, or relevant and appropriate)
is assigned. This classification refers specifically to response actions
undertaken as part of sediment remedial actions at the site. An ARAR
analysis is not required for response actions undertaken as part of a source
control event berause the state will continue to regulate those activities
under non-CERCLA environmental laws and regulations. Compliance with ARARs
will be required for upland activities only if they are specifically related
to sediment remediation (e.g., treatment, transportation, dewatering, and
disposal of dredged material).
Potential Chemical-Specific ARARs--For dredging and dredged material
disposal, chemical-specific ARARs issued at the federal level that must be
evaluated include MCLs and MCLGs under SDWA, and ambient water quality
criteria under Section 303 or 304 of the Clean Water Act. MCLs are
enforceable drinking water standards developed for public drinking water
supplies. MCLs are based primarily on health considerations, with some
allowance for cost and feasibility. MCLGs are developed under SDWA as
chemical-specific health goals and are used to set MCLs. MCLGs are set at
levels where there are no known or anticipated health effects, and include a
safety margin. Federal ambient water quality criteria are based on
laboratory bioassays and are designed for the protection of aquatic life.
In addition, RCRA incinerator regulations include a process for
establishing chemical-specific emission limitations for principal organic
hazardous constituents (POHCs). U.S. EPA has also proposed regulations to
4-9
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limit emissions from boilers utilizing contaminated materials as feedstock.
Under Section 121 (d) of CERCLA, remedial actions require a level or
standard of control for hazardous substances, pollutants, or contaminants
which at least attains MCLGs or water quality criteria where such goals are
deemed to be relevant and appropriate.
Other potential federal ARARs include ambient air quality standards
specified by the Clean Air Act and standards specified by the federal Occupa-
tional Safety and Health Act (OSHA). The federal Clean Air Act specifies
standards for suspended particulates and a limited number of chemicals.
Under OSHA, the National Institute for Occupational Safety and Health
(NIOSH) develops permissible exposure limits (PELs) and other enforceable
worker exposure guidelines for selected hazardous chemicals.
At the state level, potential chemical-specific ARARs include require-
ments for new sources including Ecology's Toxic Air Guidelines. Requirements
have also been promulgated by the Washington Industrial Safety and Health
Act (WISHA) for workers exposed to hazardous chemicals. In addition,
Ecology, under a mandate from the Puget Sound Water Quality Authority
(PSWQA), has been tasked with establishing sediment quality criteria for
Puget Sound (element P-2 of PSQWA management plan). Draft interim sediment
standards addressing long-term goals for Puget Sound were issued in June
1988, with final standards expected in June 1989. Development of sediment
standards to be applied in various sediment-related programs (e.g.,
discharge permits, dredging and disposal operations, sediment remedial
activities) will be promulgated in a phased sequence according to the PSQWA
management plan. As these standards are promulgated, they will satisfy the
definition of ARARs. Other potential state ARARs include, state water
quality standards promulgated under Chapters 90 and 173 of the Washington
Administrative Code (WAC). These regulations establish water quality
criteria as well as discharge requirements. In addition, WAC Chapter 173-
303 implements Chapter 70.105 of the Revised Code of Washington (RCW), the
Hazardous Waste Management Act of 1976, and Subtitle C of Public Law 94-580
(RCRA) establishing Washington State Dangerous Waste Regulations. These
regulations designate wastes that are dangerous or extremely hazardous to
the public health and the environment and the requirements for handling,
transfer, and disposal of dangerous and extremely hazardous waste.
At the regional level, potential chemical-specific ARARs include
emissions standards of the Puget Sound Air Pollution Control Agency
(PSAPCA). PSAPCA has generally adopted and enforces federal clean air
standards (although in some cases, regional standards are more restrictive).
However, PSAPCA can and has developed chemical-specific standards on a case-
by-case basis.
Chemical-specific TBCs--Chemical-specific TBCs that are issued at the
federal level include carcinogenic potency factors (for carcinogens) and
reference doses (for noncarcinogens). Carcinogenic potency factors and
reference doses relate to site activities through the development of human
health risks based on various exposure pathways (e.g., consumption of
seafood or ingestion of groundwater). Chemical-specific limits derived from
exposure estimates may be considered. The U.S. Food and Drug Administration
4-10
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(FDA) has developed limited criteria for maximum concentrations of hazardous
compounds in fish tissue destined for interstate transportation and sale.
These criteria exist for PCBs (2.0 mg/kg) and mercury (1.0 mg/kg). Although
those criteria .are promulgated, they are included under the TBC category
because they are based on assumptions that are not specifically relevant and
appropriate to the site. More accurate public health risk assessment
information has been developed for the site (Versar, Inc. 1985). PSDDA
interim guidelines for the disposal of dredged material in Puget Sound are
also based on defining potential problem sediments as determined by
biological effects associated with observed chemical contamination (i.e,
the AET method). PSDDA interim disposal guidelines are not codified but
have been applied and are presently being considered for adoption for
standard use by regulatory agencies in Puget Sound.
Chemical Specific Legal Applicability or Relevance and Appropriateness--
Federal ambient water quality criteria are directly applicable to alterna-
tives involving dredging or the placement of dredged material or other
material in marine waters. Federal water quality criteria and state
sediment quality criteria apply (when promulgated) to the substances in
question (dredged material), persons covered (any person), and actions
covered (dredging). State sediment quality criteria and procedures have not
been codified but will satisfy the definition of ARARs upon promulgation.
Applicability of these ARARs does not depend on the time period covered or
the types of facilities involved. Federal water quality criteria are also
applicable to confinement alternatives because these alternatives involve the
disposal of uncontaminated material. Federal water quality criteria are
applicable to nearshore disposal alternatives insofar as there is a potential
for contaminants from the dredged material to reach the adjacent water (e.g.,
water quality criteria are appropriate for use during a post-remediation
monitoring plan).
OSHA and WISHA requirements are applicable insofar as workers may be
exposed to hazardous substances during the course of remediation. Federal
clean air standards and PSAPCA standards are applicable to the extent that
materials may be released to the atmosphere during remediation (e.g.,
volatilization of contaminants during nearshore and upland placement, or
release of contaminants during incineration). SDWA MCL and MCLGs may be
legally applicable to the alternatives involving onsite disposal either
upland or nearshore if it is determined that there is an aquifer for public
drinking water sources on the site.
SDWA MCL and MCLGs, and Clean Water Act federal water quality criteria
for drinking water are relevant and appropriate to remedial alternatives
involving the onsite placement of contaminated sediment nearshore or upland.
These ARARs are relevant and appropriate primarily because they regulate
groundwater concentrations of contaminants - a factor that will have to be
considered (e.g., via post-remediation monitoring) at upland and nearshore
dredged material disposal sites. MCL, MCLGs, and water quality criteria for
drinking water are relevant and appropriate for situations where groundwater
is or may be used for drinking water. Where a groundwater aquifer is not
used as a drinking water supply and is discharging to one of the waterways,
acute and chronic marine water quality criteria are relevant and appropriate.
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Major chemical-specific ARARs for contaminated sediment remedial
alternatives are listed in Table 4-1. Chemicals listed in Table 4-1 are
priority chemicals found in one or more problem areas.
Major chemical-specific TBCs for contaminated sediment remedial
alternatives are listed in Table 4-2. These TBCs are expected to be
promulgated in the near future and will be applicable to sediment remedial
activities at that time. Included in the table are the PSDDA screening
level concentrations (below which no unacceptable adverse effects would be
expected following disposal) and the PSDDA maximum level concentrations
(above which material would be expected to be unacceptable for unconfined,
open-water disposal) (U.S. Army Corps of Engineers 1988).
Potential Location-Specific ARARs--Location-specific ARARs at the
federal level that must be evaluated include the Coastal Zone Management
Act; Clean Water Act; Marine Protection, Research, and Sanctuaries Act
(MPRSA); and the Rivers and Harbors Appropriations Act. The CZMA established
a program whereby coastal states can receive assistance in developing their
own coastal zone management program. The State of Washington developed such
a program under the CZMA and the Shoreline Management Act (described below)
effectively superceding the CZMA. The most important provisions of the
Clean Water Act with respect to the site are Section 401 (state water
quality certification for federally permitted activities), Section 402
(establishes the NPDES program), and Section 404 (establishes a permitting
and permit review process for dredging and dredged material disposal). The
most important component of the MPRSA is its provisions, requirements, and
guidelines for ocean disposal of dredged materials. The Rivers and Harbors
Appropriation Act provides the U.S. Army Corps of Engineers authority to
regulate any activities that may interfere with navigation (e.g., dredging
and dredged material disposal).
At the state level, potential location-specific ARARs include the
Shoreline Management Act, Washington Department of Natural Resources (WDNR)
guidelines and procedures for leasing submerged lands, the Toxics Control
Act, the Department of Fisheries hydraulics permit requirements, and
Department of Game hydraulics permit requirements. Under the state Shoreline
Management Act, the City of Tacoma has prepared a Shoreline Master Program
to regulate land use and construction within the coastal zone. As trustee
over the submerged lands of the state, WDNR manages all dredged material
disposal sites via a submerged lands leasing program. The Puget Sound Water
Quality Authority is planning to develop sediment criteria to identify
potential problem areas in Puget Sound based on no-observable-adverse-
effects levels. When developed, those criteria would be applicable.
Location-Specific TBCs--At the regional and local levels, potential
location-specific TBCs are limited to 1) the requirements, procedures, and
guidelines for open-water disposal specified by PSDDA; and 2) land use
requirements specified by the City of Tacoma in its shoreline plan and land
use plan (for areas outside the coastal zone). PSDDA has developed
procedures for evaluating the suitability of dredged material for unconfined,
open-water disposal, and procedures, guidelines, and criteria for establish-
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TABLE 4-1. SELECTED POTENTIAL CHEMICAL-SPECIFIC ARARs
FOR PROBLEM AREA CHEMICALS
Chemical
Antimony
Arsenic
Cadmium
Copper
Lead
Mercury
Nickel
Zinc
SDWA
MCL
(mg/L)
__
0.05
0.01
--
0.05
0.002
--
--
Marine WQC
Acute/Chronic
(mg/L)
__
0.013
0.0093
0.0029
0.0056
2.5E-05
0.0071
0.058
SDWA
MCLG
(mg/L)
—
--
0.005
1.3
0.02
0.003
--
--
NIOSH3
PEL
(mg/m-3)
0.5
0.01
0.1
1.0
0.05U
0.05b
1
--
ACGIHa
TLV
(mg/m-3)
0.5b
0.002C
0.05a
^u..
0.05
1
--
Trichloroethene
Tetrachloroethene
Hexachlorobenzene
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
Hexachlorobutadiene
Pentachlorocyclopentane
isomer
HPAH
LPAH
Methylpyrenes
Methylphenanthrene
Dibenzothiophene
2-Methoxyphenol
Dibenzofuran
4-Methylphenol
Phenol
2-Methylphenol
1-Methyl, 2-(methylethyl)
benzene
Naphthalene
2-Methylnaphthalene
Biphenyl
Pentachlorophenol
Dibenzothiophene
Ethyl benzenes
Xylenes
Bi s(2-ethylhexyl)phthalate
Alkylated benzene isomer
Benzyl alcohol
N-nitrosodiphenylamine
Diterpenoid hydrocarbon
Retene
Butyl benzyl phthalate
Aniline
0.75
0.032e
5.8
3.4E-04
0.43
0.62
0.75
0.221
0.681
35
300(
75
19
50
1
0.5
435
20b
100b
19
10
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TABLE 4-1. (Continued)
SDWA Marine WQC SDWA NIOSHa ACGIHa
MCL Acute/Chronic MCLG PEL TLV
Chemical (mg/L) (mg/L) (mg/L) (mg/m3) (mg/m3)
Phthalate esters -- 0.034
PCBs -- 3.0E-05
Total organic carbon
Total volatile solids
Oil and grease
a 8-h time-weighted average unless otherwise indicated - units in mg/m3 of air.
b 10-h time-weighted average.
c 15-min ceiling.
d Ceiling value.
e Lowest observed effect level.
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TABLE 4-2. SELECTED POTENTIAL CHEMICAL-SPECIFIC TBCs
Chemical
Antimony
Arsenic
Cadmium
Copper
Lead
Mercury
Nickel
Zinc
Lindane
Total DDTs
Total PCBs
Dimethyl phthalate
Diethyl phthalate
Di-n-butyl phthalate
Butyl benzyl phthalate
Bis (2 ethyl hexyl) phthalate
Di-n-octyl phthalate
Phenol
2-Methyl phenol
4-Methyl phenol
2,4-Dimethylphenol
Pentachlorophenol
Benzoic acid
Benzyl alcohol
Hexachlorobutadiene
Dibenzofuran
N-nitrosodiphenylamine
Hexachloroethane
Total xylene
Ethylbenzene
Tetrachloroethene
Trichloroethene
LPAHa
HPAHa
1,3-Dichlorobenzene
1 , 4-Di chl orobenzene
1,2-Di chl orobenzene
1, 2, 4-Tri chl orobenzene
Hexachl orobenzene
PSDDA
Screening Level
(mg/kg)
2.6
70
0.96
80
70
0.21
28
160
0.005
0.007
0.130
0.160
0.097
1.40
0.470
1.90
68.0
0.120
0.006
0.120
0.01
0.140
0.216
0.010
0.029
0.054
0.022
1.40
0.012
0.004
0.014
0.160
0.610
1.80
0.170
0.026
0.005
0.006
0.023
PSDDA
Maximum Level
(mg/kg)
26
700
9.6
800
700
2.1
49
1,600
—
0.069
2.50
—
—
—
—
—
—
1.20
0.063
1.20
0.029
—
0.650
0.073
0.290
0.540
0.22
14.00
0.120
0.037
0.140
1.60
6.10
18.0
—
0.26
0.05
0.064
0.230
a Regulated for individual constituents only by state regulations,
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ing unconfined, open-water disposal sites. PSDDA guidelines for chemical
and biological evaluations of dredged material are given in Appendix C.
PSDDA is in the process of developing similar guidance for other disposal
options, including conventional land disposal, nearshore disposal, and
confined disposal.
Under the Shoreline Management Act, the City of Tacoma may issue a
shoreline substantial development permit for any project with a value in
excess of $2,500, including the designation of a dredged material disposal
site. Application of Tacoma land use regulations will vary with specific
land use designations in problem areas.
The offshore, nearshore, and upland (within 200 ft of ordinary high
water) disposal of dredged material, and any other remedial alternative
involving shoreline development (e.g., construction of dredged material
treatment facilities) is subject to the specifications and guidelines set
forth in the Tacoma shoreline and land use plans. Any such development
occurring offsite but still within the coastal zone and exceeding $2,500 in
value would be required to meet the substantive requirements of a Tacoma
shoreline substantial development permit. Activities occurring offsite are
subject to the substantive and administrative requirements of Tacoma land
use regulations.
Location-Specific Legal Applicability or Relevance and Appropriateness--
Based on the determining factors listed above, Sections 404 and 401 of the
Clean Water Act and Section 10 of the Rivers and Harbors Appropriations Act
(guidance provided in 40 CFR Part 230.10 and 33 CFR Parts 320-330) are
applicable to all remedial alternatives involving dredging and disposal of
dredged material in navigable waters. The CZMA is applicable to alternatives
involving the disposal of material or construction of treatment facilities
in the coastal zone.
MPRSA requirements for ocean disposal are relevant and appropriate to
remedial alternatives involving the open-water disposal of dredged or
capping material. The MPRSA establishes guidelines and requirements for
determining the suitability of materials for ocean disposal, siting ocean
disposal sites, and monitoring dumping activities therein.
Major location-specific ARARs for contaminated sediment remedial
alternatives are listed in Table 4-3.
Potential Action-Specific ARARs—Action-specific ARARs deal with
restrictions based directly on the nature of remedial alternatives. Section
121 of CERCLA specifies that actions incorporating treatment technologies to
permanently and significantly reduce volume, toxicity, or mobility are to be
preferred. Offsite transport and disposal of contaminated substances is
also discouraged (Public Law 99-499, 17 October 1986 Section 121(b) of
CERCLA).
The alternatives developed for the Commencement Bay N/T FS encompass a
wide range of response actions providing varying degrees of public health
and environmental protection. The no-action and institutional controls
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TABLE 4-3. SELECTED POTENTIAL LOCATION-SPECIFIC ARARs
FOR CANDIDATE REMEDIAL ALTERNATIVES
Location
Requirement3
Prerequisites
Citation
Within 100-year
floodplain
Within
plain
flood-
Within coastal
zone
Oceans or waters
of the United
States
Washington State
waters
Facility must be con- RCRA hazardous waste treat- 40 CFR 264.18(b)
structed, maintained, ment, storage, and disposal
and operated to pre-
vent washout
Action to avoid ad- Action will occur in low-
verse effects, mini- lands and flat areas ad-
mize potential harm, joining inland and coastal
restore and preserve waters
natural and benefi-
cial values
Conduct activity in
manner consistent
with Washington Shore-
line Management Act
Action to dispose of
dredged and fill ma-
terial requires a
permit
Disposal of dredged
material under permit
authority of the U.S.
Army Corps of Engi-
neers
Action affecting the
natural flow of water
requires
Activities affecting coast-
al zone, including shore-
lands, tidelands, and sub-
merged lands
Oceans
United
and waters
States
of the
Executive Order
11988; 40 CFR 6
Appendix A
Coastal Zone Man-
agement Act (16 USC
Section 1451)
Washington Shore-
line Management Act
Tacoma Shoreline
Management Plan
Clean Water Act
Section 404, 401,
40 CFR 125
Marine Protection
Resources and Sanc-
tuaries Act Section
103
Rivers and Harbors
Appropriations Act
Section 10
Department of Fish-
eries and Game
Hydraulics Permit
RCW 75-20.100,
WAC 220-110
Permits are not required under SARA.
4-17
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alternatives are included to provide a baseline for evaluation and to
examine an option for meeting the objectives of the remediation effort
without implementing sediment mitigation measures. The alternatives
involving in situ capping and removal/disposal without treatment were
developed to provide effective measures for long-term contaminant isolation.
The treatment alternatives were developed to examine innovative, permanent
solutions for contaminated sediment mitigation.
CERCLA requires that the following factors be considered in reviewing
alternative remedial actions:
• Long-term uncertainties associated with land disposal
• Goals, objectives, and requirements of the Solid Waste
Disposal Act
• Contaminant persistence, toxicity, mobility, and propensity
to bioaccumulate
• Potential for adverse effects from human exposure
• Long-term maintenance costs
• Potential for future remedial actions if the identified
action were to fail, and associated human and environmental
health threats.
For the Commencement Bay N/T remedial actions, these factors must be
reviewed in view of the high volume and relatively low concentrations of
contaminated sediments. U.S. EPA guidance suggests that for sites involving
these special circumstances, treatment technologies may not be practical and
that containment options may be more appropriate (U.S. EPA 1988a). For the
most part, contaminants in the study area have demonstrated high particle
affinity, relatively low solubility, and therefore, low mobility potential.
These factors aid in minimizing the uncertainty associated with confinement
of untreated sediments. The capping and removal/disposal alternatives do
not result in the degree of permanence provided by treatment or destruction
of contaminants. However, the protectiveness associated with effective
isolation of contaminated sediments can provide a long-term solution to
observed adverse biological and potential public health impacts.
Contaminant toxicity, mobility, persistence, and propensity to
bioaccumulate were considered in the selection of indicator chemicals. All
action-oriented remedial alternatives were selected for evaluation on the
basis of their ability to minimize or eliminate the potential for adverse
effects on the environment and human health from exposure to contaminated
sediments. The alternatives are also evaluated, in part, based on the
resources at risk in the event of system failures and the difficulty
involved in implementing corrective actions.
This section is organized according to the following categories of
actions involving contaminated sediments: no action; institutional controls;
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dredging; treatment .of dredged material; and placement, disposal, or
discharge of treated dredged material and water (e.g., from dewatering,
settling, and treatment), untreated dredged material, capping material, and
treatment residues (e.g., filter cakes from water treatment operations).
No Action—The "implementation" of this alternative would result in the
nonattainment of many ARARs, including the intent of CERCLA/SARA and the
National Contingency Plan. For example, the NCR requires that selected
remedies cost-effectively mitigate and minimize threats to and provide
adequate protection of public health and welfare and the environment [40 CFR
Part 300.68(i)]. Based on evidence presented in the RI and other documents,
the no-action alternative does not accomplish this goal. Other ARARs that
would not be satisfied by this alternative include criteria for groundwater
protection (e.g., MCLs) and possibly U.S. EPA ambient water quality
criteria.
Institutional Controls—Institutional controls minimize human health
risks from hazardous substances primarily via mechanisms that prevent access
to the substances. There are many types of possible institutional controls,
including site fencing, posting of health advisories, land use restrictions,
and bans for the consumption of contaminated biota or groundwater. Site
fencing may require boundary survey work and consideration of Tacoma land
use and permitting requirements. Posting of health advisories may require
close coordination with the Tacoma-Pierce County Health Department and
consideration of their regulations and guidelines. Because of the limited
effectiveness of institutional controls alone, this alternative will fail to
satisfy major ARARs, including the intent of CERCLA/SARA. However, it is
feasible and advisable to use selected institutional controls in conjunction
with other remedial alternatives.
Dredging Activities—Dredging technologies under consideration include
hydraulic cutterhead, specialized hydraulic dredge, watertight bucket
clamshell, and mud cat. Federal action-specific ARARs relating to dredging
include the Clean Water Act (Sections 404 and 401), Rivers and Harbors
Appropriations Act (Section 10), and MPRSA. There are no state ARARs that
specifically regulate dredging at this time. However, state water quality
requirements (under Section 401 of the Clean Water Act) may be considered
during dredging activity and may be considered an action-specific ARAR as
well as a location-specific ARAR. Water quality considerations may involve
the Washington Departments of Ecology, Natural Resources, Fisheries, and
Game. The Departments of Fisheries and Game must consider the substantive
requirements for a hydraulics permit for any project that may interfere with
the natural flow of surface water. ARARs that specifically regulate
dredging in the Commencement Bay N/T area are addressed in the City of Tacoma
Shoreline Management Plan.
The substantive requirements of the Clean Water Act (including state
water quality certification), and the Rivers and Harbors Appropriations Act
are legally applicable to dredging actions on an action-specific basis
because remedial dredging satisfies their jurisdictional requirements.
Limitations on times of the year when dredging may occur are further
specified by the Puyallup Indian Tribe and the Department of Fisheries as
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the designated trustees for commercial fisheries resources. In general,
dredging is not allowed between mid-March and June, or during the fall.
It is possible that the legal applicability, or relevance and ap-
propriateness of specific requirements of dredging ARARs may vary by
problem area and by dredging technology. For example, compliance with the
substantive provisions of Sections 404 and 401 of the Clean Water Act and
state water quality requirements will be necessary for all dredging
activities. However, specific restrictions may be imposed by some agencies
under certain conditions (e.g., required use of a silt curtain by the
Department of Fisheries or Game to avoid impacts to migrating anadromous
fish).
The MPRSA does not provide requirements or guidelines for the testing of
dredged material per se and is thus not a legally applicable ARAR. However,
general guidelines for the testing of material for ocean disposal may be
relevant and appropriate for remedial alternatives involving dredging.
Treatment Activities—Categories of treatment technologies under
consideration include solids separation, incineration, solidification, and
land treatment. There are a variety of alternative treatment methods
within each of these categories. The discussion of ARARs in this section
focuses only on the above four categories.
Most ARARs for contaminated sediment treatment relate to the release or
disposal of materials resulting from the treatment process. In addition,
there may be releases to the atmosphere (e.g., from incineration), ground-
water (e.g., from infiltration of effluent or leachate), and surface water
(discharge of effluent). There may also be the need to dispose of materials
such as filters contaminated during the treatment process (see next
subheading).
Potential federal ARARs for waste treatment are currently limited to
onsite incineration and land treatment. There are proposed standards for
thermal treatment other than incinerators; for chemical, physical, and
biological treatment other than tanks, surface impoundments, or land
treatment units; and for the control of volatile organic emissions from air
stripping operations. There are no potential state ARARs for specific
candidate treatment technologies.
Disposal--Action-specific ARARs that pertain to the disposal of
materials overlap somewhat with chemical-specific and location-specific
ARARs. ARARs for the open-water or nearshore disposal of dredged material
(treated or untreated) or capping material are analogous to location-specific
(and to some extent, chemical-specific) ARARs discussed above. ARARs for
the disposal of treated and untreated dredged material and capping material
depend to a significant degree on contaminant concentrations. For example,
some materials may not meet the PSDDA chemical-specific guidelines for open-
water disposal, requiring either treatment or confined disposal. Element S-4
of the PSWQA will establish standards for disposal of sediments classified
as having adverse effects in confined disposal facilities. These standards
will meet the definition of ARARs when promulgated.
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Current U.S. EPA policy requires that any untreated, contaminated
dredged materials taken offsite be disposed of at a facility that is in
compliance with RCRA or TSCA (PCB disposal) or other appropriate federal or
state requirements, depending on the contaminants of concern and their
concentrations. The requirements for handling and disposal of treated
dredged material will depend on chemical analyses conducted following
remediation.
Action-specific ARARs may also be invoked for the disposal of effluent
from treatment processes. It is very unlikely that an effluent will be
classified as a RCRA hazardous waste or a State of Washington dangerous or
extremely hazardous waste. However in such a case, the potential ARARs
discussed above would have to be evaluated. Depending on the results of
bench-scale treatability studies, treatment wastewater may be discharged to
surface water or a publicly owned treatment works (POTW) if applicable
effluent guidelines can be achieved. Potential federal ARARs for such
actions include requirements for testing and monitoring of Section 402 of
the Clean Water Act and requirements for the discharge of effluent to a
POTW. Potential state ARARs for the discharge of treatment wastewater
include the following (see Appendix C for regulatory citations):
• Water pollution control and discharge standards that require
treatment with known, available, and reasonable methods
• Regulations for the protection of upper aquifer zones that
require protection of water quality to the extent practical
• The state waste discharge program that regulates discharges of
wastewater to groundwater
• Water pollution control regulations that provide for the use
of water quality regulations at hazardous waste sites.
All of the action-specific ARARs discussed must be evaluated because their
jurisdictional requirements are met by the candidate remedial alternatives.
Action-Specific TBCs--Action-specific TBCs relating to the Commencement
Bay N/T remedial actions would include current PSDDA guidelines for the
testing of dredged material prior to removal and disposal. TBCs for the
disposal of treated and untreated dredged material and capping material
depend to a significant degree on contaminant concentrations. In addition,
construction of treatment facilities may require consideration of the City
of Tacoma's land use plan, building codes, and grading and drainage
ordinances. It is unlikely that disposal of untreated sediment will be
allowed at a local municipal solid waste landfill within Pierce County or a
PSDDA unconfined, open-water site because of liability issues associated
with CERCLA wastes. The action level triggering sediment remediation in
Commencement Bay is expected to be very close to the level of sediment
toxicity at which unconfined, openrwater disposal of dredged material is
prohibited under PSDDA guidelines.
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Major action-specific ARARs and TBCs for contaminated sediment remedial
alternatives are listed in Table 4-4.
Large portions of the Commencement Bay N/T site are within the
boundaries of the Puyallup Indian Reservation. Environmental regulations
promulgated by the Puyallup Tribal Government will therefore need to be
evaluated as potential ARARs. Although the tribe has not adopted any
specific environmental legislation to date, it is actively pursuing the
development of laws and programs to address the control of hazardous
substances and pollution sources within its jurisdiction. The degree of
tribal involvement and the tribe's authority to promulgate environmental
regulations will vary according to the provisions of those federal environ-
mental statutes which the tribe desires to administer, and the U.S. EPA
policies and programs providing for such authority. For example:
• The Clean Water Act provides that Indian tribes may qualify
to administer programs regulating point and nonpoint sources
of pollution, dredge and fill, and other programs. Formal
delegation of these programs follows a process of review and
approval by U.S. EPA defined in Section 319 of Clean Water
Act.
• Under the Safe Drinking Water Act, the tribe may qualify for
primary enforcement status pursuant to regulatory requirements
promulgated by U.S. EPA.
• Under CERCLA, the tribe may enter into a cooperative
agreement with U.S. EPA to undertake Superfund cleanup of any
NPL sites on the reservation.
• Although U.S. EPA has confirmed its regulatory jurisdiction
regarding RCRA-regulated facilities, it may work with the
tribe in the development and implementation of RCRA programs.
4.2.3 Availability
This evaluation criterion refers to the availability of the equipment
and specialized expertise required to perform the candidate alternative as
well as the availability of the necessary treatment, storage, or disposal
capacity. Current stage of development (i.e., of the various technologies)
and potential vs. current availability are also considered.
At present, the availability of upland disposal facilities within the
Commencement Bay N/T site is uncertain. As discussed in the preliminary
screening of alternatives (Chapter 2), several potential disposal sites
within the project boundaries have been identified. However, no upland
disposal sites have been established and approved for disposal of con-
taminated dredged material in the Commencement Bay N/T project area. It was
assumed for the evaluation, however, that an upland disposal facility could
be made available within the project area. It was also assumed that agency
approval, tribal acceptance, and public acceptance could be attained. This
assumption was made based on recent guidance for remediation of Superfund
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TABLE 4-4. SELECTED POTENTIAL ACTION-SPECIFIC ARARs
FOR CANDIDATE REMEDIAL ALTERNATIVES
Action
Requirement3
Prerequisites
Citation
Upland disposal
(closure) of
RCRA hazardous
waste
Upland disposal
(containment)
of RCRA hazar-
dous waste
Upland disposal
(post closure)
Upland disposal
(groundwater
protection)
Upland disposal
of extremely
hazardous waste
Upland disposal
of solid waste
or dangerous
waste
Removal of all contam- RCRA hazardous waste placed 40 CFR 264.11,
inated material at site, or movement of 40 CFR 264.228,
waste from one area to and 264.258,
another 40 CFR
264.228(a)(2), and
264.258(6),
40 CFR 264.310
52 FR 8712
Construction of new
landfill onsite
RCRA hazardous waste placed 40 CFR 264.301,
in new landfill 264.303, 264.304,
264.310, 264.314,
Design, maintenance, 268 Subpart D,
and operation require- 264.220, 264.221
ments
Monitoring require-
ments
RCRA hazardous waste
Groundwater monitoring RCRA hazardous waste
at RCRA disposal
facilities
General protection
requirements
Disposal in state-
approved facility
Disposal in an ap-
proved surface im-
poundment
State designates as ex-
tremely hazardous waste
(EHW)
Material must
sified as EHW
not be clas-
40 CFR 264.1
40 CFR 264.90-
264.101, 265.90-
265.94
WAC 173-303-081,
WAC 173-303-140
WAC 173-303-081,
WAC 173-303-650
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TABLE 4-4. (Continued)
Action
Requirement9
Prerequisites
Citation
Dredging and
open-water or
nearshore dis-
posal of dredged
material
Dredging in waters
the United States
requires a permit
of Waters of the United States
Clean Water Act
Section 404,- 40
125
CFR
Disposal
material
permit
of dredged
requires a
Dredging or aquatic
disposal of dredged
material requires
state water quality
certification
Hydraulics permit
Requirement for a
shoreline substantial
development permit
Guidelines and cri-
teria for testing
dredged material and
establishing disposal
sites
Confined disposal
standards (S-4)
Sediment quality Limitations on sedv
and sediment ment discharges
discharge (pro-
posed) standards
Interference with natural
water flow of Washington
state waters
Clean Water Act
Section 401, 40 CFR
125
RCW 75-20.100
WAC 220-110
Disposal site within Tacoma Tacoma Shoreline
city limits Master Program
Oceans of the United States Marine Protection
Resources and Sanc-
tuaries Act
Puget Sound
Puget Sound
Puget Sound Dredged
Disposal Analysis
(under development)
Marine and fresh waters of RCW 90.48 and 90.70
the State of Washington WAC 173-204
(pending)
Incineration of
dredged material
Requirements for
incineration of RCRA
hazardous waste
Requirements for in-
cinerators to achieve
local standards, new
source requirements
RCRA hazardous waste
40 CFR 264.340-
264.999, 265.270-
265.299
PSAPCA permit is-
suance
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TABLE 4-4. (Continued)
Location
Requirement3
Prerequisites
Citation
Direct discharge Requirements and cri-
of treatment teria including corn-
system effluent pliance with federal
WQC and BAT; NPDES
permit requirements
Direct discharge to waters 40 CFR 125.123(b),
of the United States 125.122,
125.123(d)(l),
125.124
Discharge to a
POTW
Land treatment
Treatment
Requirements for dis- Discharge to Tacoma POTWs
charges to POTWs
Tacoma Pretreatment
Program
Design, monitoring,
and treatment require-
ments
Proposed standards
for treatment other
than incineration and
land treatment
RCRA hazardous waste
RCRA hazardous waste
40 CFR 403.5, 40
CFR 264.71, 264.72
Tacoma POTW Pre-
treatment Program
40 CFR 264.271,
264.273, 264.276,
264.278, 264.281,
264.282, 264.283
50 FR 40726, 40 CFR
264, 40 CFR 268.10-
268.13, 42 U.S.C.
3004(d)(3),
3004(e)(3),
6924(d)(3),
6924(e)(3)
a Permits are not required under SARA.
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which emphasizes the need to identify solutions that minimize offsite
transport of contaminants (Porter 1987)-
The availability of a nearshore disposal facility within the Commence-
ment Bay N/T site has been enhanced by the recent emergence of Slip 1 in
Blair Waterway as a potential site. This facility has been designated for
filling by the Port of Tacoma, and has a capacity of approximately
900,000yd3. Once again, it was assumed that agency approval, tribal
acceptance, and public acceptance could be attained.
The potential for offsite disposal of untreated contaminated dredged
material has largely been dismissed because of inherent difficulties
associated with dewatering and transport of marine sediment, and the asso-
ciated costs of both transport and disposal. However, if treated sediment
is determined to meet state and federal criteria for designation as nonhazar-
dous waste, the material could feasibly be placed in a sanitary or demolition
landfill. Concentrated residues that may be generated by implementation of
one or more treatment alternatives will be dealt with in strict accordance
with state and federal regulations, including disposal at a RCRA-approved
facility, as appropriate.
4.3 COST CRITERIA
Order-of-magnitude costs were estimated for each combination of
remedial alternative and problem area. Costs were grouped into the following
categories:
• Construction and implementation - Costs for engineering
design, development of specifications, dredging, transporta-
tion, treatment, intertidal habitat replacement, and disposal.
• Operation and maintenance - O&M costs associated with all
post-disposal onsite activities, including monitoring.
Engineering site inspections of containment structures,
erosion control, drainage, repairs, and landscape upkeep are
all aspects of O&M. The latter category includes refertili-
zation, mowing, and general maintenance of site vegetation.
Monitoring activities are designed for both short- and long-term
surveillance of containment structure or cap performance. In practice,
activities should begin just prior to the disposal operation and remain
intense for the first year, tapering off over the course of an assumed 30-yr
program. In this manner, failure to initially contain sediment contam-
inants can be detected immediately. In addition, frequent monitoring after
completion of the remedial action allows an assessment of the rate and
extent of contaminant migration that can be expected to occur over the long
term. Assuming that initial monitoring efforts confirm predicted rates of
contaminant migration based on pre-implementation bench-scale tests and
modeling studies, it is reasonable to assume that the sampling frequency can
be reduced over time. The lack of contaminant releases within approximately
1 yr of sediment disposal indicates that the level of monitoring can be
reduced.
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Cost estimates for specific items within each category were normalized
to 1988, using an annual inflation rate of 6 percent. For yearly costs
associated with monitoring, operation, and maintenance, the present worth
was calculated using a 10 percent interest rate. A discussion of the
estimation method, assumptions, and information sources used is presented in
Appendix D (along with summary tables for each remedial alternative).
4.4 IDENTIFICATION OF PREFERRED ALTERNATIVES
Guidance for identifying a preferred remedial alternative for each of
the nine high priority problem areas in the Commencement Bay N/T study area
is provided in Section 121 of SARA, the NCR, and U.S. EPA guidance (Porter
1987; U.S. EPA 1988a). The SARA revisions to CERCLA mandate that the
remedial actions selected have the following characteristics:
• Are protective of human health and the environment
• Attain federal, tribal and state public health and environment
requirements
• Are cost-effective
• Use permanent solutions and alternative treatment or recovery
technologies to the maximum extent practicable.
Treatment is defined as those activities that permanently and significantly
reduce the toxicity, mobility, or volume of the hazardous substances.
Selection of permanent remedies that have not yet been implemented under
similar circumstances are authorized under the law. However, the preference
for selection of an alternative that eliminates the need for long-term
management (i.e., a permanent treatment) may not be practical in some
circumstances. Recent draft RI/FS guidance (U.S. EPA 1988a) indicates that
permanent treatment may not be reasonable in circumstances where site
conditions, limitations in technologies, and extreme costs may be controlling
factors. For example, sites with very large volumes of potentially low
concentration wastes, such as municipal landfills and mining sites, fall
into this category. Contaminated dredged materials from the Commencement
Bay N/T area may also fall into this category. It is further stated in SARA
that remedies requiring offsite transport of untreated contaminant materials
should be the least favored action where practicable treatment technologies
are available.
The following process was used to identify the preferred alternative in
each problem area. First, effectiveness and implementability of candidate
alternatives were summarized. Results are shown in Chapters 5-13 as
oversized narrative tables. Next, the candidate alternatives were compared
with one another. Results are shown as "evaluation summary" tables, with
ratings of high, moderate or low in the major evaluation criteria. The
rationale and method followed when assigning ratings are described below in
Sections 4.4.1-4.4.8. The preferred alternatives were identified from these
summary tables. This approach was developed to identify one preferred
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remedial alternative with the broadest applicability for each of the nine
Commencement Bay N/T problem areas, but the process is complicated by the
variable nature of both the contaminants and the environmental and opera-
tional features within the problem areas. For this reason, a brief review
and analysis was conducted to identify other alternatives that may be
suitable for sediments contaminated by a particular class of compounds
(e.g., inorganic contaminants) or located within a specific environmental
setting (e.g., intertidal areas). A discussion of this analysis is presented
for each problem area, following description of the preferred alternative.
4.4.1 Short-Term Protectiveness
Community, worker, and environmental protection during implementation
of the candidate alternative are evaluated under the short-term protective-
ness criterion.
A candidate alternative rates high for short-term protectiveness if
implementation is expected to pose only minimal risks to workers and the
community. Community exposure risks are expected to be low, as site controls
can be readily implemented for all alternatives to minimize potential
contact with contaminated dredged material. Worker exposure potential is
lowest for alternatives in which contaminated sediments are left in place.
Alternatives involving dredging increase worker exposure risks, but process
controls, available personal protective equipment, and the relatively low
level of hazard associated with contaminated dredged material contact could
preserve a high rating for this aspect of an alternative. Environmental
protection during implementation is highest when sensitive resource areas
are not damaged or destroyed by the alternative. Environmental controls
exist for most alternatives (e.g., silt curtains for dredging, emission
controls for incineration). However, short-term impacts are expected for
loss of habitat due to dredging, capping, or disposal operations.
Moderate ratings were assigned to candidate alternatives involving
effective remediation technologies with an increased potential for some
adverse impacts, but where engineering and safety controls are feasible. In
this case, a moderate to high risk of exposure to workers may be anticipated,
but safety controls are adequate to significantly reduce the exposure
potential. Process-related risks associated with treatment alternatives
prolong exposure potential, and therefore generally reduce the short-term
protectiveness rating. A moderate rating was also given to an effective
technology that poses moderate risk to a low sensitivity environment and
that involves risk control methods which are difficult or costly to
implement.
Candidate sediment remedial alternatives received low ratings if they
offer only minor overall benefits, with high probability of producing or
allowing significant environmental impacts, and where engineering and safety
controls are not feasible. This rating was also assigned to candidate
alternatives that pose a high risk to sensitive environments or populations,
with inadequate mitigative controls or monitoring capabilities.
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4.4.2 Timeliness
The comparison of the candidate alternatives for timeliness is based on
their ability to mitigate observed biological impacts rapidly without
compromising the integrity of the various process options. The time
required to obtain concurrence from the various state and federal agencies
on all components of the remediation system, including treatment, storage,
and disposal facilities was considered. In all cases, source control
measures were assumed to be implemented rapidly and effectively to facilitate
subsequent implementation of sediment remediation.
A high rating was assigned to alternatives that can be completed within
1-2 yr of implementation of adequate source controls. These alternatives
would have to rely on currently available equipment and facilities, with
minimal bench-scale or pilot testing required. Alternatives that produce
immediate environmental benefits were also rated high.
Moderate ratings were assigned to candidate alternatives that can be
implemented within 2-5 yr following implementation of adequate source
control. These alternatives would generally require some testing and
development of technologies because there has been little or no field
application to date. Alternatives that must be modified because the
sediments are of marine origin or that require lengthy review times for any
aspect of the technology were also rated moderate.
Low ratings for timeliness were assigned to candidate alternatives
that require greater than 5 yr to implement and complete. Included in this
category are alternatives that require substantial treatability testing,
that have low production rates, or where significant delays in development
may be expected (e.g., determination of treatment feasibility, siting of a
land treatment facility).
4.4.3 Long-Term Protectiveness
The comparison of candidate alternatives in terms of long-term protec-
tiveness is based on their effectiveness in permanently mitigating the
observed adverse biological impacts of sediment contaminants in the
Commencement Bay N/T project area. Reliability, long-term risks and
benefits, uncertainties remaining after implementation of the alternative,
environments or populations at risk, and the effectiveness of monitoring
following remediation were all considered. Included in the comparison of
long-term protectiveness are the criteria for reviewing future exposure
potentials, reliability, and public health and environmental protection.
The candidate alternatives that rate high afford a high degree of post-
remediation reliability and security and allow monitoring to be readily
implemented. System failures are detectable long before public health or
environmental impacts occur. High ratings were also assigned to facilities
that would cause minimal adverse impacts if any critical component failed,
and to alternatives that permanently reduce public health and environmental
risks.
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Moderate ratings were given to alternatives that present a higher
potential for future exposure, yet are readily monitored or amenable to
engineering controls. This rating also applies to alternatives that are
less reliable, yet present minimal risk of adverse impacts from system
failures. Moderate ratings were assigned to alternatives that remove or
isolate contaminants with minimal on- or offsite risks.
Low ratings for long-term protectiveness were assigned to alternatives
involving significant risks after remediation. For alternatives with a high
degree of uncertainty and where significant adverse public health or
environmental impacts would be expected from system failures, low ratings
were applied. Alternatives involving a high potential for future exposure,
great uncertainty concerning monitoring, or uncertainty concerning con-
taminant fate and transport also received a low rating.
4.4.4 Reduction in Contaminant Toxicitv. Mobility, or Volume
The comparison of candidate sediment remedial alternatives in terms of
reduction in toxicity, mobility, or volume focuses on the extent to which
an alternative results in the permanent destruction or detoxification of
sediment contaminants. The permanent treatment of waste contaminants
affords a higher level of overall effectiveness than does isolation (Porter
1987).
High ratings for reduction in contaminant toxicity, mobility, or
volume were assigned to alternatives that result in significant and irrever-
sible reductions with minimal residual material. High ratings were also
assigned to alternatives that may be less effective in reducing overall
residual mass yet generate residual materials that can be classified as
nonhazardous waste.
Moderate ratings are applicable to alternatives that provide some
degree of reduction in toxicity, mobility, or volume. This rating was
applied to alternatives incorporating treatment technologies that generate a
large volume of less mobile and toxic waste.
Low ratings apply to alternatives that lack a treatment element. All
capping and dredge/disposal alternatives rank low because they isolate
contaminated sediments without substantially affecting the contaminants
themselves, although mobility is physically limited.
4.4.5 Technical Feasibility
Technical feasibility is based on implementability and the reliability
of the process options that make up each alternative, as judged by past
performance in similar applications, the importance of long-term O&M to
success of the system, and the effectiveness of monitoring systems in
tracking performance.
High ratings for technical feasibility were applied to alternatives that
can be implemented with little bench- or pilot-scale testing and that
4-30
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incorporate highly reliable, proven procedures. High ratings are also
applicable to alternatives that require minimal O&M or where O&M procedures
are well established, effective, and easily implemented as part of the
ongoing performance of the treatment or isolation process. For those
alternatives where performance monitoring is focused and allows early
detection of system failures, high ratings were also given.
Moderate ratings for technical feasibility are applicable to alterna-
tives that appear to be technically feasible, yet require extensive testing
or development prior to implementation. Moderate ratings were also applied
to alternatives that require more extensive, routine maintenance using
proven procedures. Where monitoring requirements are more extensive but the
systems are estimated to be effective in detecting performance problems,
moderate ratings are also appropriate.
Low ratings for technical feasibility apply to alternatives that are
complex and difficult to implement or that involve technologies that are
significantly constrained by site conditions. Low ratings were given to
alternatives that require extensive O&M following remediation, and where
intensive O&M is critical to system success.
4.4.6 Institutional Feasibility
Institutional feasibility is based on the ability of alternatives to
adequately address all applicable or relevant and appropriate regulations
and other nonpromulgated agency guidelines, advisories, and policy that
require consideration. The comparison of alternatives includes an assessment
of the likelihood that ARARs can be met and that TBCs can be favorably
addressed.
High ratings for institutional feasibility were applied to alternatives
that comply with all ARARs as well as all relevant guidance and policy.
Alternatives that are flexible in terms of timing and that incorporate
components likely to be approved by the regulatory agencies were also rated
high.
Moderate ratings apply to alternatives that meet ARARs and meet the
intent of most relevant guidance. Moderate ratings also apply to alterna-
tives likely to receive agency acceptance, albeit through negotiations.
Low ratings apply to alternatives that do not comply with ARARs and
present problems with respect to agency policy and guidance that are probably
unresolvable.
4.4.7 Availability
Availability is based on the accessibility of necessary equipment,
specialized expertise, and disposal facilities. The highest ratings for
availability were assigned to alternatives that use existing and readily
accessible materials, facilities, and personnel. A high rating was also
applied to alternatives that can use existing facilities to accommodate
treated or altered contaminated sediments.
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Moderate ratings were applied to alternatives involving technologies
that are regarded as feasible but require adaptation to the site-specific
conditions. This rating applies to alternatives incorporating technologies
that require bench-scale or treatability testing to define design parameters.
This rating also applies to alternatives that rely on disposal facilities
that have been identified as part of previous studies in the Commencement
Bay area, but have not been formally approved or developed for use.
Low ratings were applied to alternatives that rely totally on unproven
technologies; on technologies that require personnel and equipment not
currently available in the project area; or on the use of disposal or
treatment facilities not currently available or planned, or that appear to
entail a high degree of uncertainty in their development.
4.4.8 Cost
The comparative evaluation of cost-effectiveness among alternatives can
only be conducted following the evaluation of the effectiveness and
implementability factors. This process allows the overall effectiveness of
each alternative to be assessed, based on the objectives for the Commencement
Bay N/T remediation program. These objectives include mitigation of observed
biological impacts and long-term protection of the environment and public
health. Cost comparisons are most appropriate after identification of
candidate alternatives that offer the best balance of predicted results. In
conducting a cost comparison of final candidates, consideration must be
given to the statutory goal of permanently and significantly reducing
contaminant toxicity, mobility, or volume, because alternatives that involve
feasible permanent solutions generally require additional capital funds for
implementation.
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5.0 HEAD OF HYLEBOS WATERWAY
Potential remedial actions are defined and evaluated in this section
for the head of Hylebos Waterway problem area. The waterway is described in
Section 5.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 5.2 provides an overview of contaminant
sources including site background, identification of known and potential
contaminant reservoirs, remedial activities, and current site status. The
effects of source control measures on sediment contaminant concentrations
are discussed in Section 5.3. Areas and volumes of sediments requiring
remediation are discussed in Section 5.4. The detailed evaluation of the
candidate sediment remedial alternatives chosen for the problem area and
indicator problem chemicals is provided in Section 5.5. The preferred
alternative is identified in Section 5.6. The rationale for its selection
is presented, and the relative merits and deficiencies of the remaining
alternatives are discussed. The discussion in Section 5.7 summarizes the
findings of the selection process and integrates required source control
with the preferred remedial alternative.
5.1 WATERWAY DESCRIPTION
Hylebos Waterway is designated as a navigational waterway with a
required maintenance depth of 30 ft below MLLW. The problem area designated
as the head of Hylebos Waterway extends roughly 1 mi from the head of the
waterway (which is approximately 16,500 ft from the mouth), to a point
approximately 11,000 ft from the mouth of the waterway. Both turning
basins in the waterway are located in this problem area. At their widest
points, the lower turning basin measures approximately 750 ft and the upper
turning basin measures approximately 1,000 ft. Subbottom profiling of
Hylebos Waterway showed that midchannel depths in the area average approxi-
mately 33 ft below MLLW, with depths varying across the channel bottom
between 30 and 40 ft below MLLW (Raven Systems and Research 1984). Depths
in the northwestern reaches of the head of Hylebos Waterway problem area
were fairly constant at 40 ft below MLLW. Sediments within the waterway are
typically silty sands with an average composition of 65 percent fine-grained
material (with a range of 44-78 percent) and an average clay content of
20 percent (Tetra Tech 1985b). The waterway has been characterized as
showing a reduction in sedimentation rates from the mouth to the head (Tetra
Tech 1987b).
Hylebos Waterway was formed by dredging the Puyallup River delta in the
early 1920s. Since that time, the southern shoreline of the waterway has
become heavily industrialized. Industrial development along the north shore
has not been as extensive as along the south shore, due principally to the
limited land area available between the waterway and the steep bluffs. An
5-1
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illustration of the waterway and the locations of nearby industries are
shown in Figure 5-1.
Dredging by the Port of Tacoma and the U.S. Army Corps of Engineers has
changed the shape and size of Hylebos Waterway. When it was created in the
1920s, it extended only to the point of what is now the lower turning basin,
near the northwestern end of the problem area, In the mid-1950s, the Port
of Tacoma extended the waterway approximately 3,800 ft (Tetra Tech 1986c).
Subsequent dredging by the U.S. Army Corps of Engineers widened the upper
reaches of the waterway and created the upper turning basin at the head of
the waterway (Dames & Moore 1982).
5.1.1 Nature and Extent of Contamination
An examination of sediment contamination data obtained during RI/FS
sampling efforts (Tetra Tech 1985a, 1985b, 1986c) and historical surveys has
revealed that sediments in the head of Hylebos Waterway contain elevated
concentrations of both organic and inorganic materials. PCBs, HPAH, arsenic,
and zinc were identified as Priority 1 contaminants in the waterway.
Priority 2 contaminants that have been detected in the waterway include
copper, antimony, lead, nickel, mercury, tetrachloroethene, and phenol. The
following compounds exceeded their AET value at only one station and are
therefore considered Priority 3 contaminants: methylpyrene, methylphenan-
threne, dibenzothiophene, ethylbenzene, xylene, chlorinated benzenes,
chlorinated butadienes, bis(2-ethylhexyl) phthalate, benzyl alcohol, and an
alkylated benzene isomer. Available data suggest that these contaminants
in the head of Hylebos Waterway have relatively high particle affinity with
a low volatility or solubility potential (Tetra Tech 1987c).
Fish in Hylebos Waterway had significant accumulations of PCBs, mercury,
and phthalates in muscle tissues and significantly elevated prevalences of
liver lesions (Tetra Tech 1985b).
Arsenic, HPAH, and PCBs were selected as indicator chemicals for the
head of Hylebos Waterway. Surface sediment enrichment ratios (i.e., ratio
of observed concentration to long-term cleanup goal) for these three con-
taminants were higher over a greater area than for other identified problem
chemicals. These contaminants were also selected as indicators on the basis
that they represent contaminant loading to the waterway from potential
sources of contamination including Kaiser Ditch, Pennwalt, log sorting
yards, Hylebos Creek, Kaiser Aluminum, Tacoma Boatbuilding Company, General
Metals, and storm drains (see Section 5.2).
Concentrations of arsenic exceeding the long-term cleanup goal of
57 mg/kg were observed in the southeastern-most reaches of the problem area
within the upper turning basin, between the two turning basins, and in the
northwestern-most areas in the vicinity of the lower turning basin. The
available data indicate that a major source of arsenic exists near the head.
Concentrations of HPAH exceeding the long-term cleanup goal of
17,000 ug/kg cover the entire central portion of the problem area, primarily
in the area between the two turning basins. Concentrations peaked in the
5-2
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Figure 51 Head ol Mylobos Waierway • Existing induslnos .uui
busiitessos
-------
center of the problem area and decreased towards both the head and mouth.
The high HPAH concentrations appear to be associated with an accumulation of
HPAH-contaminated organic material in the sediment (Tetra Tech 1985a).
Concentrations of PCBs exceeding the long-term cleanup goal of 150 ug/kg
cover a large percentage of the problem area with high levels noted in the
two turning basins and the south shoreline. PCB concentrations were highly
variable in Hylebos Waterway sediments. A relatively patchy distribution
remained after concentrations were normalized to sediment organic carbon
content, suggesting that this contaminant does not come from the major
carbon sources in the waterway (e.g., Kaiser Ditch, silt from the Puyallup
River) but from multiple local, and possibly historic, sources (Tetra Tech
1985a). PCB concentrations peaked approximately 12,000 ft from the mouth of
the waterway, in the vicinity of the Pennwalt Chemical Corporation facility.
Dredging in that vicinity by Pennwalt is believed to have influenced the
observed surficial sediment distribution of PCBs (Tetra Tech 1985b).
Concentrations observed in sediments following dredging were similar to
those found in deeper layers of undisturbed portions of the waterway.
Area! and depth distributions of arsenic, HPAH, and PCBs are shown in
Figures 5-2, 5-3, and 5-4, respectively. Concentrations in the figures are
normalized to long-term cleanup goals, such that values above 1.0 define
problem sediments. The cleanup goal for arsenic was set by the AET for
benthic infaunal abundance depression. The cleanup goal for HPAH was
determined by the AET for the oyster larvae bioassay. The cleanup goal for
PCBs is based on data for bioaccumulation of the contaminant in English sole
muscle tissue.
Included in Figures 5-2, 5-3, and 5-4 are contaminant depth profiles
based on core samples from the head of Hylebos Waterway. Arsenic concen-
trations were either variable with depth or displayed surface minima,
suggesting that metals loading is recent but may be decreasing (Tetra Tech
1985a, 1987c). The possibility that there is a significant groundwater
source of arsenic to the waterway complicates the interpretation of sediment
profile data. Depth profiles suggest that arsenic contamination exceeds the
cleanup goal to a depth of approximately 1.0 yd.
Although the sediment profiles indicate that HPAH concentrations-vary
somewhat with depth, for the waterway as a whole greater concentrations of
HPAH were observed in subsurface horizons (Tetra Tech 1985a). A conservative
estimate based on depth profiles suggest that HPAH contamination exceeding
the cleanup goal can be expected to a depth of approximately 0.5 yd.
Deep cores collected during the RI indicate that historical discharges
of PCBs were greater than current discharges. Resolution of the depth
profiles obtained during the FS sampling was constrained by analytical
limitations (e.g., chlorinated interferences). Although the results were
somewhat inconclusive, surface minima were observed for the station at the
head of the waterway, suggesting that loading has decreased. The profile
collected adjacent to the Pennwalt Chemical Corporation (near the 1982
dredging operation site) showed variable concentrations of PCBs with depth.
5-4
-------
ARSENIC (mg/kg)
0 20 40 (0 tO 100 170 140 160
I I I I ,1 I '1 I I I, I I I I I -
t 2
RATIO TO CLEANUP GOAL
HY-93
MLAN LOWEH LOW WAI til
A FEASIBIITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
• SEDIMENT SURVEYS CONDUCTED
IN 1984
V SEDIMENT SURVEYS CONDUCTED
BEFORE 1964 (1979 1961)
TT^TJ SEDIMENT CONCENTRATIONS
^iiiiJ EXCEED TARGET CLEANUP GOAL
900
lee)
HY-91
HY-93
Figure 5-2. Areal and depth distributions of arsenic in sediments at the head of Hylebos Waterway,
normalized lo long-term cleanup goal.
-------
HY-93
MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1981)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
HPAH (|ig/kg)
0 1.0 2.0 0.3
RATIO TO CLEANUP GOAL
0.5-
1.0-
1.5-
2.0 J
• HY-91
- HY-93
Figure 5-3. Areal and depth distributions of HPAH in sediments at the head of Hylebos Waterway,
normalized to long-term cleanup goal.
-------
0 1 000 2 OOO 3 OOO 4 000
I t
01 10 20
RATIO TO CLEANUP COAL
MEAN LOWEH LOW WAI EH
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (197&1981)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
900
leel
motor*
300
Figure 5-4. Areal and depth distributions of PCBs in sediments at the head of Hylebos Waterway,
normalized to long-term cleanup goal.
-------
Depth profiles suggest that PCB contamination exceeding the long-term
cleanup goal can be expected to a depth of approximately 0.5 yd.
5.1.2 Recent and Planned Dredging Pro.iects
General Metals dredged 2,000 yd^ of sediment from the head of Hylebos
Waterway in October 1988 (Vail, R., 9 November 1988, personal communication).
The sediment was deposited on General Metals property. The company has a
10-12 yr permit to dredge in the head of Hylebos Waterway every other year.
The volume of material to be dredged is unspecified in the permit.
Weyerhaeuser and Pennwalt have requested dredging permits from the
U.S. Army Corps of Engineers. Weyerhaeuser intends to begin work in 1988 or
early 1989 (Sinclair, J., 9 November 1987, personal communication). Pennwalt
wants to install bulkheads and fill (U.S. Army Corps of Engineers, 27 October
1987, personal communication).
Businesses and industries that responded when queried about future
dredging plans are itemized below.
• Weyerhaeuser has not planned any major dredging projects. In
1988 or early 1989, the company needs to repair the ramp for
removing logs. Approximately 40 yd-* of material will need to
be removed before the concrete can be poured (McLain, D.,
22 October 1967, personal communication). Disposal of this
material is currently planned for a local landfill.
• Glacier Sand and Gravel knew of no planned dredging projects
in the head of Hylebos Waterway, but expected that dredging
would be necessary sometime within 10 yr (Johnson, J.,
22 October 1987, personal communication).
• Streich Brothers, Inc., U.S. Gypsum, Murray Pacific Yard #1,
McFarland Cascade, Hylebos Boat Haven, and Manke Lumber have
not planned any dredging projects (Rain, T., 22 October 1987,
personal communication; Anonymous, 22 October 1987a, personal
communication; Miller, L.( 22 October 1987, personal communi-
cation; Snap, C., 22 October 1987, personal communication;
Norlund, Mrs., 22 October 1987, personal communication;
Goeoze, D., 22 October 1987, personal communication).
The Port of Tacoma has not identified any areas within the head of
Hylebos Waterway that require dredging (White, M., 28 August 1987, personal
communication). However, the Port of Tacoma and the U.S. Army Corps of
Engineers have suggested that navigational channels in the Commencement Bay
area may be deepened in the future to accommodate vessels with deeper
drafts.
5.2 POTENTIAL SOURCES OF CONTAMINATION
This section provides an overview of the sources of contamination to
the sediments in the head of Hylebos Waterway (Table 5-1) and a summary of
5-8
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TABLE 5-1. HEAD OF HYLEBOS WATERWAY - SOURCE STATUS3
("hpinic.al /Group
l'( Ms
Arspnir
/ i nr
liMd
Ant Imony
Nil krl
MCI < in y
III'AII
Mplhylpyrenes
tn
1 Mpl hy Iphenanthrene
Itilipn/ol hiophene
Ipl rar hloroplhpnp
1 1 hy Mirn/rnp
Xy loops
Chlorinated ben/enes
fhlorinalPd huladipnes
I'hcnol
His(2 plhylhpnyl )phthalate
Allyl.llrd lirn/cne 1 some'
Urn/ y 1 all nho 1
Chemical
Segment 1
--
1
1
2
1
3 (HY-15.
IIY 16, IIVI7)
3 (IIY-17)
3 (IIY 17)
3 (IIY-17)
2
--
J (IIY 16,
HY 17)
Priority1"
Segment 2
1
2
2
2
2
2
2
2
3 (HY-22)
3 (IIY 22)
3 (HY-22)
2
3 (HY-22)
3 (HY-22)
3 (HY-22.
HY 01)
3 (HY 22)
3 (HY 22)
Sources
Unknown
General Metals
Kaiser Ditch
Pennwalt outfal 1
Storm drains
Log sort yards
llylebos Creek
Kaiser Aluminum,
Kaiser Ditch
Ubiquitous oi 1
spills
Pennwalt out (all
Pennwalt ground -
water infiltration
Kaiser Ditch
fast Channel Ditch
Unknown
c
Unknown
Source ID
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Potential
Yes
Potential
Yes
Yes
No
c
No
Source Loading
No
No
Yes
Yes
Yes
Yes
Yes
Insufficient data
No
Yes
No
Insufficient data
Insufficient data
No
No
c
Source Status
Hi slorical
Ongoing
Ongo i ng
Ongoing
Ongoing
Ongoing
Ongoing
Historical, runoff from
disposal onsile
Ongoing, sporadic
Ongoing, past disposal
practices
Ongoing, past disposal
practices
Ongo i ng
Ongoing
Historical
c
c
Sediment Profile Irenils
Surface minimum
Surface minimum, or
variable
Variable
Undetected at al 1 depth
horl/ons
Surface minimum
c
c
c
a Sourrp informal ion and sediment information blocks apply to all chemicals In the
l ivc group, not to individual chemicals only.
'' I in I'riniily 1 ihi>mic
-------
available loading information for the contaminants of concern. Log sorting
yards [Wasser/Winters, Louisiana Pacific, Weyerhaeuser, Cascade Timber
Yard #2, and 3009 Taylor Way (sometimes called Dunlap Towing)] occupy nearly
all of the southern and eastern shorelines in the upper portion of the
waterway (see Figure 5-1). Pennwalt Chemical Corporation is located on the
south shore of the waterway east of Lincoln Avenue, and was one of the first
industries established in the area producing chlorine and inorganic
compounds for local pulp and paper industries.
Two smelting industries were established along the upper part of the
waterway in the early 1940s. Ohio Ferro Alloys, located on the south side
of Taylor Avenue about 13,500 ft from the mouth of the waterway, was built
in 1942. Ohio Ferro Alloys produced chrome, silica, and ferrosilicate.
After the plant closed in 1972, the Port of Tacoma bought the property, which
has recently been used as a log sorting yard. The second smelting company,
Kalumite Inc./Olive Company, opened in 1941-42 on the site now owned by
Kaiser Aluminum and Chemical Company. Kaiser took over operation of the
plant in 1949.
Other facilities located adjacent to the problem area include Tacoma
Boatbuilding Company, Glacier Sand and Gravel, Jones Chemical, Petroleum
Reclaiming, and General Metals (see Figure 5-1). Permitted discharges to
the problem area include General Metals (State permit No. 5006), Pennwalt
Chemical Corporation (NPDES permit No. WA0003115), Glacier Sand and Gravel
(NPDES permit No. WA003402), and Tacoma Boatbuilding Company (State permit
No. WA003710-9) (Figure 5-5). Nonpermitted discharges to the problem area
include an 8-in concrete pipe, Hylebos Creek, Kaiser Ditch, Morningside
Ditch, East Channel Ditch, Pennwalt East Seep, Pennwalt West Seep, the
Pennwalt east stormwater drain, a 6-in concrete pipe, a Pennwalt discharge
pipe, and groundwater seeps along the south bank. There are approximately
20 additional surface water discharges to the head of Hylebos Waterway.
As indicated in Table 5-1, the inorganic contaminants present represent
a group of chemicals with numerous ongoing sources including Kaiser Ditch,
Pennwalt, several log sorting yards, Hylebos Creek, and storm drains.
Tacoma Boatbuilding Company has also been indicated as a source of inorganic
contaminants to the problem area based on a recent site inspection (Ecology
and Environment 1987). Much of the metals contamination at the head of
Hylebos Waterway may ultimately be derived from ASARCO waste material.
ASARCO slag is a constituent of the ballast used at the log sorting yards.
In addition, Hylebos Creek has been identified as a source of metals that may
originate from upstream landfills that received baghouse dust from the
smelter. Wet scrubber sludges from Kaiser Aluminum have been identified as
a source of HPAH. Oil spills are also a potential source of PAH and
associated organic chemicals (i.e., methylpyrenes, methylphenanthrene, and
dibenzothiophene). No major sources of PCBs were identified in the problem
area during the RI sampling effort. However, high concentrations of PCBs
were subsequently observed in several catch basins at General Metals
(Stinson et al. 1987).
5-10
-------
Relerence: Telra Tech (1965b).
meters
1000
Figure 5-5. NPDES-permitted and nonpermitted discharges to Hylebos Waterway.
-------
.5.2.1 Kaiser Aluminum
Site Background--
Kaiser Aluminum and Chemical Corporation operates an aluminum pro-
duction plant on a 96-ac site near the head of Hylebos Waterway. Production
capacity is approximately 80,000 ton/yr, roughly half of which is fabricated
into aluminum rod at the plant. The facility was built in 1942 by the
Defense Plant Department, and operated by 01 in Inc. until 1946. Kaiser
Aluminum acquired the property in 1946 and continued operations until 1958,
when economic conditions led to cessation of production. Production resumed
in 1964 and has continued to the present day.
In the early 1950s, Kaiser Aluminum installed a wet scrubber system to
reduce air emissions. The system generated a wastewater containing aluminum,
reduction cell bath materials, carbon, and condensed pitch volatiles
(Hanneman 1984). Wastewater was discharged to a series of settling (sludge)
ponds for removal of suspended solids. Clarified water was recycled or
discharged. Generation of wet scrubber sludge ceased in 1974, when a dry
scrubber system was installed. In 1983, analysis of wet scrubber sludge
revealed HPAH concentrations of up to 5 percent (Stanley, R., 27 June 1983,
personal communication; Landau Associates 1984). On the basis of HPAH
content and results of bioassay tests, Ecology characterized the sludges as
"extremely hazardous wastes in accordance with WAC 173-303." High concentra-
tions of HPAH were also found in Kaiser Ditch (discharge 52 in Figure 5-6),
which drained the sludge ponds. These results, in conjunction with the
finding that waterway sediments near the Kaiser Ditch outfall contained
elevated concentrations of HPAH, led to identification of Kaiser as a
potential source of HPAH contamination to Hylebos Waterway (Tetra Tech
1985a).
Atmospheric emissions of PAH from Kaiser Aluminum were also identified
as a possible source of contamination to Hylebos Waterway. These PAH could
enter the waterway as direct deposition, or as runoff via Kaiser Ditch from
areas receiving direct deposition (Tetra Tech 1985a). HPAH emissions from
production pot rooms have been quantified and found to be significant
(Nord, T.L., 1 November 1983, personal communication; Fenske, F=, 25 April
1985, personal communication). However, a link between atmospheric HPAH
emissions and increased concentrations of HPAH in Hylebos Waterway has not
been established.
Contaminant Source Identification--
Approximately 65,000 yd^ (88,000 tons wet weight) of wet scrubber
sludge deposits rest on the western side of the property. The sludge
management area consists of three contiguous unlined surface impoundments
covering approximately 11 ac. This area is the primary source of available
HPAH on Kaiser Aluminum property. The potential for wet or dry deposition
of HPAH from atmospheric emissions has not been evaluated.
In late 1986, a 3,000-gal spill of PCB-contaminated transformer oil
occurred at the Kaiser Aluminum facility. PCBs in the oil were measured at
5-12
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Figure 5-6. Surlace water drainage pathways lo the head of
Hylobos Waterway. •-
-------
17 mg/kg. After the spill, contaminated soil was removed and disposed of at
the Arlington, OR hazardous waste disposal facility- Groundwater in the
vicinity of the spill was collected with the aid of trenches, and treated
using an oil/water separator. This water was discharged to the City of
Tacoma wastewater treatment plant under a temporary permit.
Recent and Planned Remedial Activities--
In April 1983, Ecology issued Kaiser Aluminum an order to determine the
nature and extent of sludge deposits on plant property, and the nature and
extent of sludge contamination in surface and groundwater. In 1984, Kaiser
Aluminum installed silt curtains adjacent to the Kaiser Ditch to keep
sludges out of the ditch. Also in 1984, 1,400 yd3 of soil contaminated with
HPAH was removed from adjacent properties and consolidated on the Kaiser
Aluminum site (Davies, D., 15 May 1988, personal communication). In June
1985, following completion of the characterization study, Ecology issued a
new order requiring Kaiser Aluminum to undertake a groundwater monitoring
and testing program, and establish a sludge management plan. The groundwater
monitoring program (Landau Associates 1987) was completed and a plan for
onsite management of the sludge was proposed. Conducted by Landau Associates
(1987), the groundwater monitoring program included a hydrogeological
characterization of the site and 2 yr of monitoring (eight quarterly
sampling events between August 1985 and May 1987). Water samples collected
from wells placed around the sludge deposits contained very low (<10 ug/kg)
concentrations of total HPAH, indicating that subsurface migration of HPAH
is negligible. However, the thin-layer chr9matography analytical method
used is considered to be only semi-quantitative. The proposed sludge
management plan involves consolidating sludge from the three impoundments
into one enclosure, capping it and monitoring the groundwater. The sludge
management closure plan was submitted to Ecology in September 1987.
Negotiation of a consent decree (under Chapter 70.105B RCW or the Model
Toxics Control Act) between Ecology and Kaiser Aluminum for remediation of
the wet scrubber sludge disposal area is scheduled to resume in early 1989.
Kaiser Aluminum has also installed a tide gate at the mouth of Kaiser
Ditch and re-routed its NPDES-permitted discharge of process wastewater.
The tide gate prevents the waterway from backing up into Kaiser Ditch and
carrying away additional sediments. Process water,, which had been channeled
through the sludge ponds, is now routed to Blair Waterway. The NPDES permit
requires monitoring' for pH, fluoride, total suspended solids, oil and
grease, and benzo(a)pyrene as an indicator of HPAH. No benzo(a)pyrene has
been detected in the effluent (Fenske, F., 4 May 1988, personal communi-
cation) .
Air emission monitoring for HPAH has been ongoing at the plant and
Ecology is in the process of determining whether additional controls need to
be implemented (Fenske, F., 28 September 1987, personal communication).
5-14
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5.2.2 U.S. Gypsum
Site Background—
A landfill site formerly owned by U.S. Gypsum was identified during the
RI as a potential source of arsenic in Hylebos Waterway. The landfill was
situated on 2.6 ac between Route 99 and Interstate 5 west of Milton. Hylebos
Creek (see Figure 5-6) runs along the southeastern edge of the site for
250 ft and discharges into Hylebos Waterway less than 2 mi downstream.
The landfill was used intensively between 1971 and 1973, and became
inactive in 1979. Approximately 17,000 yd3 of waste was placed in the
landfill, including paper, asphalt-coated paper, shot, and off-specification
mineral fiber. Approximately 10 percent of the waste was in the form of
baghouse dust produced during the manufacture of mineral fiber and was rich
in arsenic (21.7 percent by weight). Other metals of concern in the
baghouse dust are lead (6.4 percent), zinc (2.8 percent), and copper
(1.0 percent). The shot and off-specification mineral fiber contained much
less arsenic than the baghouse dust (Dames & Moore 1983).
Contaminant Source Identification--
The U.S. Gypsum landfill was unlined and depths of waste fill ranged
from 1 to 13 ft. The fill was generally sloped towards Hylebos Creek at the
southeastern portion of the site. No barriers existed on the slope between
the creek and the landfill area, suggesting that surface water runoff could
have traveled directly to the creek. A drainage ditch between Interstate 5
and the east boundary of the landfill collected runoff from the highway and
the north end of the landfill. Sampled waste from the southern portion of
the site, which contained most of the baghouse dust, was analyzed for
EP toxicity. Only arsenic concentrations exceeded the EP maximum contaminant
level of 5.0 mg/L. A single sampling of Hylebos Creek water above and below
the landfill site indicated that there was very little contamination of the
creek water from the site (Dames & Moore 1983). Concentrations of arsenic,
lead, zinc, and copper remained below the primary drinking water standards.
A similar effort by Johnson and Norton (1985b) during both low water and high
water stream conditions indicated that the site was not a major contributor
of arsenic to the creek, and that the arsenic loading potential from the east
side drainage ditch was low. However, arsenic concentrations in stream
sediment samples obtained by Johnson and Norton (1985b) were higher down-
stream of the landfill than upstream of the landfill during both wet and dry
seasons. This pattern was not observed for other metals.
Groundwater beneath the site appears to have been contaminated by
landfill leachate. Between August 1982 and June 1983, groundwater was
sampled from wells positioned on or near the site and samples were analyzed
for metals (Dames & Moore 1983). Arsenic concentrations exceeded the
primary drinking water standard of 0.05 mg/L in eight of the nine monitoring
wells at the site. In the two wells that continued to be monitored for
10 mo after site cleanup (see below), arsenic concentrations ranged from
3.0 to 9.4 mg/L. Zinc and copper concentrations consistently remained below
the primary standards of 5 and 1 mg/L, respectively. Lead concentrations
5-15
-------
generally remained below the primary drinking water standard of 0.05 mg/L
but in a few instances were higher, in one case by almost a factor of 10.
Recent and Planned Remedial Activities--
Fill and underlying contaminated soil were removed from the U.S. Gypsum
landfill site in the fall of 1984. Excavation was discontinued once the
EP toxicity concentration of arsenic in soil dropped below the target level
of 0.5 mg/kg established by Ecology (U.S. Gypsum Company, no date; Reale, D.,
14 September 1987, personal communication). Groundwater monitoring has
continued since that time in two wells located near the southeastern
boundary of the site along Hylebos Creek. Between 6 March and 6 July 1986,
arsenic concentrations in groundwater from groundwater wells at the landfill
consistently remained below 0.5 mg/L, which is Ecology's preliminary target
cleanup criterion (Reale, D., 14 September 1987, personal communication).
No post-cleanup data are available on arsenic concentrations in Hylebos
Creek downstream of the site. The landfill site has recently been developed
into a parking lot. As a result of the remedial action it is unlikely that
the U.S. Gypsum landfill site poses a long-term threat of continuing arsenic
input to Hylebos Creek.
5.2.3 B&L Landfill
Site Background--
A landfill owned by B&L Trucking is located near the Surprise Lake
Drain west of Milton. The fill covers approximately 17.3 ac and consists
primarily of soil and wood wastes scraped from the surface of log sorting
yards on the Tacoma tideflats (Johnson and Norton 1985b). Fill operations
at the site began in 1978 and continued through 1980, at which time the
Tacoma-Pierce County Health Department prohibited further placement of fill
(Pierce, D., 18 March 1986, personal communication). The department
approved placement of fill in low uncontoured areas at the site, but
apparently there was very little disposal activity during 1981-1982
(Pierce, D., 18 March 1986, personal communication). By the middle of 1984,
B&L had installed screening equipment at the site, and expected to recycle
the bark wastes into a usable product (Carr, J., 11 July 1984, personal
communication). In 1985, studies implicating the landfill as a source of
metals contamination prompted the owner to cap a substantial portion of the
landfill with clean fill material in an attempt to reduce leachate production
(Burdorff 1985). More than half of the fill area was capped (Carr, J.,
6 January 1987, personal communication). By approximately the middle of
1985, a court order resulted in the cessation of all fill activities (Olczak
1987).
Contaminated leachate from the B&L landfill could reach Hylebos
Waterway by entering the Surprise Lake drainage, which empties into Hylebos
Creek.
5-16
-------
Contaminant Source Identification--
The B&L landfill consists primarily of soil and wood wastes from log
sorting yards in the Tacoma tideflats. Metal-laden ASARCO slag used as
ballast at the log sorting yards was also collected with the solid and wood
waste for disposal at the landfill. It also contains some shredded auto-
mobile wastes. More than half of the landfill is capped with an unknown
amount of clean fill.
Recent and Planned Remedial Activities--
The only remedial actions at the site to date are cessation of disposal
activities and capping. Ecology believes that this cap is inadequate and
plans additional action. A unilateral order from Ecology in April 1987
instructed the owner to implement a remedial investigation and Feasibility
Study (FS) (Reale, D., 17 September 1987, personal communication). The
Ecology order was subsequently appealed to the Pollution Control Hearing
Board. Ecology cancelled the order due to the inability of the owner to
comply and the intent of Ecology to notify an expanded list of potentially
liable persons to request immediate site stabilization, full investigation,
and remediation under Chapter 70.105B RCW. Following a site inspection in
September 1987, Ecology oversaw preparation of a site stabilization plan
(focused FS) to control contaminated leachate. Ecology is currently
negotiating with several PRPs to perform a RI/FS. It is anticipated that a
RI/FS will begin in late 1988.
5.2.4 Pennwalt
Site Background--
Pennwalt Corporation's Tacoma plant, which began operations in 1929, is
located at 2901 Taylor Way an<3 borders the southern shore of Hylebos
Waterway. Chemicals currently produced at the facility are chlorine, sodium
hydroxide, sodium chlorate, chlor (a bleaching agent), and hydrochloric
acid. Chlorine and sodium hydroxide are produced via the electrolysis of
salt brine. During the Commencement Bay Nearshore/Tideflats (N/T) RI and
subsequent source evaluation refinement (Tetra Tech 1985a, 1986c), the
Tacoma plant was identified as a potential source of chlorinated ethenes,
arsenic, lead, copper, zinc, and nickel.
Chlorinated ethenes and other chlorinated hydrocarbons historically
were generated as by-products of chlorine production, primarily as a con-
sequence of using linseed oil-impregnated graphite anodes (AWARE 1981).
Passage of product gas through cooling towers resulted in the condensation
of water and chlorinated hydrocarbon by-products. This condensate was
deposited in onsite- evaporation ponds known as the Taylor Lake Waste
Treatment and Disposal Area. In 1975, titanium anodes replaced the graphite
anodes, resulting in significantly reduced production of chlorinated
hydrocarbon by-products (High, 0., no date, personal communication). In
1981, .the discharge of cooling tower condensate into the Taylor Lake
evaporation ponds was discontinued. The waste stream is now passed through
a chlorine stripper and discharged to Hylebos Waterway through the NPDES-
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permitted main outfall. Measurable concentrations of chlorinated ethenes
were not detected in the single analysis of that effluent after the cooling
tower condensate had been routed to the main outfall (Yake, B., 9 March
1982, personal communication).
Intertidal sediments along the Pennwalt waterfront contained the
highest levels of arsenic measured in Hylebos Waterway during the RI (Tetra
Tech 1985a). Arsenic discharges from the Pennwalt site stem from past
production of the pesticide sodium arsenite (tradename Penite) and disposal
of corresponding waste sludges. The pesticide was produced between 1939 and
1974 at the Tacoma plant. Waste sludges were land-filled pnsite between the
chlorine production facility and the Taylor Lake evaporation ponds. Before
1981, three outfalls discharging surface water runoff to Hylebos Waterway
were contributing a substantial portion of total arsenic input (Tetra Tech
1985a). After completion of a site hydrogeology study by AWARE (1981),
Pennwalt disconnected these outfalls and rerouted the surface runoff to the
main outfall. From 1981 to early 1986, arsenic loading from the main outfall
was estimated to be between 3 and 5 Ib/day (Hart-Crowser & Associates 1986).
Pennwalt's NPDES permit was revised in 1986 to require reduction of arsenic
discharges in the main outfall. Since that time, Hart-Crowser & Associates
(1986) have reported that arsenic discharges from the permitted outfall have
been virtually eliminated. However, arsenic is not included as a monitoring
variable under the NPDES permit for the outfall, and measured arsenic
concentrations in the discharge have not been provided for Ecology to
substantiate.
• Elevated concentrations of copper, lead, zinc, nickel, and mercury in
sediments adjacent to Pennwalt coupled with loading data associated with the
main outfall implicated Pennwalt as an important source of these metals
(Tetra Tech 1985a, 1986c).
Contaminant Source Identification--
Contaminant reservoirs onsite consist of various ponds, moats, and
pits. Site descriptions presented below are based primarily on information
from an AWARE (1981) report, and information from Ecology personnel, except
where indicated.
The Chlorate Pond has been inactive since 1979. It contains approxi-
mately 780 yd-5 of sludge. The constituent of primary concern is hexavalent
chromium, which is included as dichromate in the sodium chlorate product as
a corrosion inhibitor.
Taylor Lake intermittently received sludges from brine settling tanks.
The sludges consist primarily of calcium carbonate and magnesium hydroxide.
There was no standing water in Taylor Lake during the AWARE (1981) study.
The lake is currently inactive.
The West Taylor Lake extension is contiguous with the larger Taylor
Lake. The extension received wastewater containing chlorinated organics
during 1974 and 1975. In December 1975, the extension became inactive,
although it continues to contain brine muds deposited in Taylor Lake. The
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remaining waste deposits in the extension consist of 760 yd3 of sludge.
This area is currently inactive.
Until 1985, the 0.3-ac Asbestos Pond received wash water containing
participate asbestos. The two cells of the pond contain a total of
approximately 900 yd-^ of sludge. One of the cells contained approximately
70,000 gal of supernatant at the time of the AWARE (1981) study.
In 1975, the Cell Room Pond, a 0.8-ac disposal site, began receiving
chlorine-rich wastewater from chlor-caustic production. The pond is an
act'ive holding area to permit dissipation of residual chlorine. It has
also received some brine muds from Taylor Lake. Samples of both supernatant
and sludges from the Cell Room Pond were reported as being nonhazardous
(AWARE 1981). However, the sampling procedure used may have resulted in an
inaccurate waste designation (Michelena, T., 4 May 1988, personal communi-
cation) .
The Taylor Lake Moat, also known as the Taylor Lake Waste Treatment and
Disposal Area, encircled most of the above areas, and was closed by
Pennwalt in 1981. Sludge from the moat was moved to the southern corner of
Taylor Lake (Hart-Crowser & Associates 1987a). While active, the moat
collected leachate from the pond system. Collected leachate was recycled
back to the ponds. Liquid and solid samples collected from the moat before
it closed were reported as nonhazardous (AWARE 1981). However, questionable
sampling procedures may have resulted in an inaccurate waste designation
(Michelena, T., 4 May 1988, personal communication).
EP toxicity arsenic concentrations in all samples from the Taylor Lake
area obtained during the AWARE (1981) study were below 0.05 mg/L, indicating
that this area was probably not an existing source of arsenic contamination
to Hylebos Waterway.
The Wypenn Pond, located near the southwest corner of the Pennwalt
site, is less than 0.1 ac in surface area and was constructed in 1970. It
received discharge from a nearby oil skimmer and basement water from the Ag
Chem Building. In addition, the pond received discharge from laboratory
sinks, presumably from the Ag Chem Building. The site is now closed and
apparently has been graded and landscaped. Supernatant and sludge samples
collected before closure were reported as being nonhazardous (AWARE 1981).
EP toxicity arsenic concentrations in the sludge and supernatant were
1.7 and 2.5 mg/L, respectively.
Waggoner's Wallow is a 0.36-ac moat system in the salt storage area.
It was constructed in 1969 as a holding area for absorber liquid. Waste
streams from the sodium hypochlorite production facility are currently
discharged to Waggoner's Wallow (Hart-Crowser & Associates 1987b). The moat
generally consists of sludges, with little standing water. .Sludge sampled
from the moat was nonhazardous (AWARE 1981).
The Ag Chem waste pits are inactive. The Ag Chem waste pits received
drums and bottles of various chemicals and solvents used during pesticide
research. The pits were covered with soil and planted with grass. Soil
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samples collected from the Ag Chem waste pits were nonhazardous, but
resulted in EP toxicity arsenic concentrations of up to 1.2 mg/L (AWARE
1981). However the procedure used for sample collection from the Ag Chem
waste pits may also have resulted in an inaccurate waste designation
(Michelena, T., 4 May 1988, personal communication).
The Penite waste disposal area consisted of three ponds and one burial
pit. Waste deposited at the site included sodium arsenite (i.e., Penite)
sludges, pipes containing Penite sludge, drums of various plant wastes, and
drums of Ag Chem wastes. Two soil samples collected from the Penite waste
disposal site exceeded EP toxicity arsenic concentration limits (52 and
300 mg/L) and were therefore considered hazardous (AWARE 1981).
The Pennwalt Tacoma facility's 1985 NPDES permit contains maximum daily
average discharge limits for copper, lead, nickel, total chlorine, total
suspended solids, pH, and flow. The facility has repeatedly violated pH and
copper limits specified in this permit (White, M., 9 May 1988, personal
communication). The NPOES permit does not require Pennwalt to monitor for
arsenic. However, the permit does require Pennwalt to determine the source
of arsenic in the wastewater discharge, and to implement measures for
mitigating or eliminating the source. Hart-Crowser & Associates (1986)
reported that measures taken to reduce arsenic contamination in the
wastewater were successful. As indicated, Ecology has not received data to
support this assertion (White, M., 9 May 1988, personal communication).
Additional elements of the NPDES permit are as follows:
• Only noncontact cooling water may be discharged from the
sodium chlorate facility. Cooling water must periodically be
monitored for chromium content to verify the integrity of the
cooling system.
• No discharge is permitted to Hylebos Waterway from the
Asbestos Pond, Taylor Lake, Waggoner's Wallow, Cell Room
Pond, or Wypenn Pond.
• No discharge of asbestos to the waterway is permitted.
• Process wastewaters from hydrochloric acid production may be
discharged through the outfall, but must not cause an ex-
ceedance of the NPDES effluent limits.
According to Hart-Crowser & Associates (1986), the dominant input of
arsenic to Hylebos Waterway from the Pennwalt Tacoma plant is via ground-
water. Groundwater data generated by Kennedy/Jenks/Chilton (1987a) to
evaluate arsenic mitigation alternatives indicate that the source of
arsenic to the contaminated uppermost aquifer beneath the site is the former
Penite waste disposal area. Maximum arsenic concentrations in groundwater
(greater than 1,000 mg/L) were observed in the vicinity of the former Penite
disposal area and emanating in a northeasterly direction. A groundwater
concentration gradient between 100 and 1,000 mg/L was observed surrounding
the plume maximum (Kennedy/Jenks/Chilton 1987a). The outer bound of the
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groundwater plume was defined by an arsenic concentration of 1.0 mg/L and
intersected the bank of Hylebos Waterway along approximately an 800-ft
distance. Samples from wells installed near the plant boundary had arsenic
concentrations typical of background levels (0.017-0.3 mg/L). Data collected
in 1986 from the intermediate aquifer directly beneath the center of the
plume revealed arsenic concentrations ranging from less than 0.2 to 1.2 mg/L
(Hart-Crowser & Associates 1986), suggesting that the aquitard below the
uppermost aquifer confines arsenic migration (Kennedy/Jenks/Chilton 1987a).
The site characterization report and final engineering evaluation work plan
for the groundwater arsenic mitigation program are currently under review by
Ecology (Reale, D., 18 May 1988, personal communication).
The arsenic soil sampling program in the former Penite waste disposal
area was completed in 1987 (Kennedy/Jenks/Chilton 1987b). This project
was conducted concurrently with the uppermost aquifer arsenic character-
ization in an effort to provide a comprehensive assessment of site con-
ditions. Arsenic concentrations greater than 10,000 mg/kg and as high as
190,000 mg/kg were found within a layer 2-7 ft below the ground surface.
Leachate testing conducted on the highly contaminated soils produced high
levels of arsenic in leachate. These data suggest that arsenic in soil at
the facility can be dissolved in the groundwater (Kennedy/Jenks/Chilton
1987b).
Groundwater is probably the only existing source of chlorinated hydro-
carbons from the Pennwalt site, since wastes containing these contaminants
are no longer produced in significant quantity. In April 1984, bank seepage
samples collected by Johnson (23 July 1984, personal communication) along
Pennwalt property contained 110 ug/L hexachloroethane, 120 ug/L chloroform,
and 340 ug/L tetrachloroethene.
Recent and Planned Remedial Activities—
Pennwalt is currently under a consent decree issued by Ecology in July
1987. Terms of the decree require Pennwalt to implement a comprehensive
site characterization by late 1988. The essential elements of the study
involve sampling, with organic and inorganic analysis of groundwater, surface
impoundments, surface water runoff, Wypenn Pond area soils, and Penite
areas. A consent decree issued in August 1986 in response to a suIfuric
acid spill at the facility requires that an operations and maintenance plan
be developed for all pipes carrying fluids.
The groundwater and Penite area soil sampling portion of the site
characterization completed in 1987 was designed to evaluate and recommend
actions to mitigate the impact of arsenic contamination in the uppermost
aquifer. Pennwalt recommended placement of a slurry wall to contain
groundwater arsenic contamination in conjunction with placement of a low
permeability cap. To provide an inward hydraulic gradient within the
confinement system, approximately 94,000 gal of groundwater will be
extracted and transported for offsite disposal at a RCRA compliant facility
(Kennedy/Jenks/Chilton 1987a).
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Under the surface impoundment program, samples will be collected from
the Chlorate Pond, Asbestos Pond, Taylor Lake, Cell Room Pond, Taylor Lake
Moat, and Waggoner's Wallow. Except for dissolved metals, the same analyses
conducted on groundwater samples will also be conducted on surface impound-
ment samples. Surface water runoff will be sampled and analyzed during the
surface water quality program. All samples will be analyzed for pH, volatile
organics, and total metals. In the Wypenn Pond area study, impoundment
usage history will be further characterized, and soils in the area will be
analyzed for PAH.
5.2.5 General Metals. Inc.
Site Background--
General Metals of Tacoma, Inc. is an active scrap metal recycling firm
located along Hylebos Waterway at 1902 Marine View Drive. The facility
prepares scrap ferrous metals from automobiles, railroad cars, and locomo-
tives for shipment overseas. Clear evidence linking contamination of
Hylebos Waterway to General Metals was not presented during the RI (Tetra
Tech 1985a). Nevertheless, the high concentrations of metals in the
waterway coupled with the nature of past and current operations at the site
led to General Metals being considered a possible source of metals. General
Metals is also considered a potential source of PCBs to the waterway based
on the presence of the contaminant in several catch basins onsite (Stinson
et al. 1987).
Contaminant Source Identification--
Contaminant sources at General Metals include buried brine sludges, fill
material covering them, PCB-contaminated soil, and possibly hydrocarbon-
contaminated soil.
Between 1972 and 1977, when a portion of the property was owned by
Occidental Chemical Corporation, a portion of the site was used for disposal
of approximately 13,000 tons of process sludge. The brine sludges making up
this waste resulted from the sodium chloride purification process and
contained small amounts of chlorinated hydrocarbons, heavy metals, and
asbestos (Feller and Monahan 1981). When General Metals assumed ownership
of the property, ASARCO slag, ground car interiors, dredge spoils from
Hylebos Waterway, and pit run material were deposited over the area used by
Occidental for waste disposal. This cover is believed to be at least 4 ft
thick.
For an undetermined period of time, transformers containing PCBs were
stored on the grounds at General Metals. Limited testing initiated by
Ecology demonstrated the presence of PCBs in soil and surface water runoff
from the site. PCB levels of 21 ppm and above have been detected in
sediments collected from four catch basins (Stinson et al. 1987). Ground-
water quality at the site has not been characterized.
Oils and lubricants generated during the metals reclamation process are
handled and stored at General Metals. Petroleum products are generated from
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the scraping of locomotives and automobiles, and from maintenance of the
machine shop and equipment. Improper handling of these waste petroleum
products has led to various incidences of contamination. The extent of the
problem and potential for contamination of the waterway remains uncharac-
terized.
Recent and Planned Remedial Activities--
In 1987 and 1988, Ecology conducted three site inspections at General
Metals: an inspection to determine the nature of the PCB problem, a Class II
hazardous waste and water quality inspection, and a TSCA hazardous materials
inspection related to the PCB problem. The firm is under an administrative
order and penalty, issued by Ecology in August 1987, to remove the inactive
PCB-containing transformers from the site and to submit a work plan for
complete site characterization. The liquid contents of the transformers have
since been removed and the cases decontaminated (Morrison, S., 29 September
1987, personal communication). The work plan for the RI/FS was submitted in
March 1988. The administrative order also requires that the firm initiate
site stabilization activities. These actions will focus on monitoring and
modifying the site drainage system (Morrison, S., 4 May 1988, personal
communication).
5.2.6 Log Sorting Yards
Site Background--
More than half of the log sorting yards in the Commencement Bay N/T
area (i.e., 7 of 12) discharge to Hylebos Waterway. Log sorting yards
occupy nearly all of the southern shoreline of upper Hylebos Waterway and
several areas throughout the middle portion of the waterway. Of the seven
yards discharging to Hylebos Waterway. Cascade Timber Yard #2, 3009 Taylor
Way (Dunlap Towing), and Wasser/Winters are currently inactive. The
Wasser/Winters site has been inactive for nearly 2 yr (Stefan, F.,
18 June 1987, personal communication). It is likely that some of the sites
will no longer be used as log sorting yards.
The log sorting yards were identified as sources of arsenic, copper,
lead, and zinc (Tetra Tech 1985a, 1986c; Sweet-Edwards & Associates
et ai. 1987). In addition, antimony, cadmium, and nickel have been found in
surface runoff from the yards (Norton and Johnson 1985a). The log sorting
yards were initially implicated as sources on the basis of the relationship
between metals in the ASARCO slag used as ballast in the yards and sediment
concentrations of those metals in the waterway. Subsequent analyses of
samples of surface runoff from the sites confirmed the presence of the
contaminants in runoff (Norton and Johnson 1985a).
Contaminant Source Identification--
The primary reservoir of contaminants at the log sorting yards is the
ASARCO slag used as ballast. Analyses of ASARCO slag revealed the following
ranges of concentrations (Tetra Tech 1985a, 1986c): 7,300-9,000 mg/kg
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arsenic, 5,000 mg/kg copper, 5,000 mg/kg lead, and 18,000 mg/kg zinc. Slag
was used primarily between 1975 and 1980.
The pathways for contaminants to reach the waterway are direct surface
runoff; surface water runoff to creeks or ditches that drain into the
waterway; and groundwater discharges to the waterway, creeks, or ditches.
Wood chips and sawdust scraped from the surfaces of the yards are also
contaminated with scraped and pulverized slag.
Recent and Planned Remedial Activities-
No remedial activities at the log sorting yards have occurred to date
(Morrison, S., 4 May 1988, personal communication). Investigative activities
are currently being conducted at the following four sites:
• Wasser/Winters - The Wasser/Winters log sorting yard is the
subject of a consent order between the Port of Tacoma and
Ecology. A work plan and a preliminary site characteriz-
ation/interim remediation FS (Sweet-Edwards & Associates et
al. 1987) has been completed. The U.S. EPA Field Investiga-
tion Team has installed several groundwater wells and
collected groundwater data. A proposal submitted by the Port
of Tacoma in August 1987 to mitigate contamination problems
associated with soils, slag, and wood waste was rejected by
Ecology. In January 1988, the Port of Tacoma agreed to
prepare an amended proposal for an alternative form of site
remediation for mitigation of both surface and groundwater
contamination (Stefan, F., 21 January 1988, personal
communication). Investigations expected to begin in May
1988 include groundwater and surface water monitoring.
• 3009 Taylor Way (Dunlap Towing) - A consent decree between
Pennwalt and Ecology was formalized, and the first quarterly
report completed in October 1987. Wet-weather sampling was
scheduled for completion between November 1987 and January
1988, and a focused FS submitted in March 1988 is under
Ecology review. The site RI work plan was approved with
revisions by Ecology in December 1987. Initiation of RI
activities has begun (Reale, D., 4 May 1988, personal
communication).
• Cascade Timber Yard #2 - A consent order was issued in
spring 1987, but Cascade Timber refused further negotiation.
A site inspection was completed by the U.S. EPA Field
Investigation Team in March 1987.
• Louisiana Pacific - Surface water drainage field studies were
completed in 1987 under an administrative order issued by
Ecology. A groundwater investigation work plan was submitted
in November 1987. In March 1988, the administrative order
was amended to include this groundwater investigation. A FS
work plan was received by Ecology in January 1988. Ecology
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plans to negotiate with Louisiana Pacific to amend the
administrative order again to include the FS (Reale, D.,
4 May 1988, personal communication).
5.2.7 Tacoma Boatbuilding Company
Site Background--
Tacoma Boatbuilding Company has operated a general ship construction
facility on Hylebos Waterway since 1969. Fill material was used in
developing the property for its current use. However, no ASARCO slag was
reportedly used (Ecology and Environment 1987).
Tacoma Boatbuilding Company is involved in new ship construction
although approximately 5 percent of the work has included refurbishing older
craft. Waste-producing operations include sandblasting, painting, and metal
cleaning. A metal slag (believed to be a copper smelting by-product) is
used for sandblasting. Sandblasting is currently performed in an enclosed
building. Historically, sandblasting was performed near the covered
bulkhead area (Ecology and Environment 1987).
Contaminant Source Identification--
A site inspection was conducted by Ecology and Environment in January
1987. Sandblast grit, soil, and sediment from a drainage ditch and storm
drain were sampled and analyzed for the variables included on U.S. EPA's
Target Compound List. However, data for pesticides, PCBs, and acid/base/neu-
trals were rejected during a quality assurance review. Therefore, only
volatile organic compounds and metals values were reported.
Sandblast grit from two locations had elevated concentrations of arsenic
(particularly older grit), copper, and zinc. Neither sample exhibited
concentrations that exceeded the EP toxicity regulatory limits specified in
WAC Chapter 173-303.
Two composite sediment samples were collected from a drainage ditch on
the west side of the property adjacent to the General Metals facility. This
ditch receives runoff from a limited portion of the Tacoma Boatbuilding
Company property as well as an undetermined amount from General Metals. In
both cases, arsenic, copper, and zinc concentrations were elevated over the
long-term cleanup goals of 57, 390, and 410 mg/kg, respectively. For a given
metal, concentrations in the two samples were quite different, indicating
spatial variability of metals concentrations in the ditch. In general,
metals concentrations in composite soil samples collected at several
locations across the site were similar to background samples collected
(Ecology and Environment 1987).
Metals concentrations in sediment from a storm drain (HY-36) that
discharges from the Tacoma Boatbuilding Company to Hylebos Waterway were
greater than corresponding long-term cleanup goals. Enrichment ratios were
1.6 (estimated) for arsenic, 7 for copper, and 23 for zinc. Concentrations
of copper, lead, and zinc in a surface water sample from HY-36 did not meet
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marine chronic ambient water quality criteria. Concentrations of copper and
zinc also exceeded marine acute ambient water quality criteria. Arsenic was
also detected in this discharge.
Recent and Planned Remedial Action--
Ecology is currently involved in a shipyard pollution prevention
education program. The program includes workshops to inform shipyard
owners of best management practices and NPDES application procedures.
Although shipyards in the Commencement Bay area are not currently permitted
under the NPDES program, Ecology plans to write permits for all shipyard
facilities. These activities are tentatively scheduled for 1989. Permit
requirements will include provisions to prevent sandblast grit and other
materials from entering the waterways, as well as monitoring requirements
for oil and grease, turbidity, and metals.
5.2.8 Storm Drains
The major storm drains discharging into the head of Hylebos Waterway
(see Figure 5-6) are the Pennwalt Chemical storm drains (HY-708, HY-056),
Kaiser Ditch (HK-052), East Channel Ditch (HY-054), and Morningside Ditch
(HY-028). Runoff from the Pennwalt site is discussed in Section 5.2.4.
The Kaiser, East Channel and Morningside Ditches are discussed below.
Kaiser Ditch--
Process wastewater from Kaiser Aluminum was historically discharged
indirectly to Kaiser Ditch until about 1985. Stormwater runoff is the only
source of flow to the ditch now. Kaiser Ditch receives runoff from the
Kaiser Aluminum facility, Cascade Timber Yard #2, Weyerhaeuser log sorting
yard (paved), and 3009 Taylor Way (Dunlap Towing) log sorting yard (Tetra
Tech 1985b). Kaiser Aluminum appears to be the largest single source of
HPAH to the Hylebos Waterway via the Kaiser Ditch (Tetra Tech 1985a).
East Channel Ditch--
The East Channel Ditch was originally installed on an easement through
the Pennwalt property to provide surface drainage for the Ohio Ferro Alloys
property (now Port of Tacoma property - Murray Pacific log sorting yard)
located on the south side of Taylor Way. This area (approximately 30 ac)
currently drains to Kaiser Ditch (HK-052).
The East Channel Ditch (HY-054) currently drains approximately 15 ac
comprising the portion of the Pennwalt property located east of the Taylor
Lake and Cell Room Pond areas, and the western boundary of the 3009 Taylor
Way log sorting yard area (Figure 5-6). The 3009 Taylor Way log sorting
yard, is presently inactive. It is likely that Pennwalt Chemical will fill
in the East Channel Ditch in the near future (High, 0., 17 August 1987,
personal communication).
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The City of Tacoma has widened Taylor Avenue and installed curbs,
gutters, and storm drains to collect road surface runoff. Runoff from the
section of Taylor Avenue opposite the Pennwalt property has been rerouted
from the East Channel to the Kaiser Ditch system (Baughman, P., 17 May 1988,
personal communication). There was some concern that excavation of a ditch
for the storm drain system would intercept the groundwater contaminant plume
from beneath the Pennwalt property and cause disposal problems. The city
investigated groundwater conditions along the proposed storm drain route to
determine if contaminated groundwater in the area would be a problem. Prior
to initiating construction activities, a waste containment site was con-
structed as a contingency if construction monitoring revealed subsurface
contamination. Slightly elevated organic vapor readings were noted in the
Pennwalt vicinity on one occasion and some excavation materials were
temporarily held in the containment facility. In addition to the temporary
containment site, several interception trenches and dams were constructed to
prevent groundwater intrusion into the construction area.
In the past, the East Channel Ditch also received leachate from the
Taylor Lake drainage moat on the Pennwalt property via an 8-in PVC pipe
(HY-055). (See Section 5.2.4 for description of wastes contained within the
area surrounded by the moat.) The moat was closed and covered in 1981 by
Pennwalt (AWARE 1981). Little data are available to characterize contaminant
loadings from the leachate in the storm runoff ditch. A single sediment
sample collected from the runoff ditch leading to the East Channel Ditch
exhibited a pH of 9.5 and arsenic concentration (EP toxicity) of 4.0 mg/L
(AWARE 1981). Discharge of leachate from Pennwalt to the East Channel Ditch
was stopped in 198i when the moat was closed and the PVC pipe was plugged.
Runoff from the Petroleum Reclaiming property may also have discharged
to the East Channel Ditch in the past. Petroleum Reclaiming recycles waste
oils for use as industrial burner fuel through dehydration and solids
removal. The site was regraded about 5.5 yr ago to direct surface water
runoff to a pit onsite, from which it is recycled through the plant
(Richland, D., 17 August 1987, personal communication). Trucks are unloaded
directly over the pit to reduce spill hazards.
Morningside Ditch--
The Morningside Ditch (HM-028) serves approximately 600 ac located on
the north side of Marine View Drive. The drainage basin includes part of
East Tacoma, extending north from Marine View Drive to about SW 347th Street
(Figure 5-7). Discharge from the ditch is composed of surface water runoff
and discharges from the Woodworth gravel washing operations (Young, R.,
19 August 1987, personal communication). There are no NPDES-permitted
industrial discharges in the basin. Annual runoff in the drainage basin is
estimated at about 400 ac-ft/yr (0.6 ft-Vsec) based on average rainfall of
37 in and a runoff coefficient of 0.2 (Viessmann et al. 1977). Land use
distribution is approximately 50 percent residential use, 40 percent
undeveloped (tree covered), and 10 percent industrial use. The Woodworth
gravel pit and associated facilities constitutes the majority of the
industrial land in the basin.
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NORTHEAS,T;|TACef
TACOMA
Figure 5-7. Drainage basin for Morningside Ditch
5-28
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5.2.9 Loading Summary
Summary loading tables for the Priority 1 and 2 contaminants of
concern for the head of Hylebos Waterway (i.e., arsenic, copper, lead,
mercury, nickel, zinc, tetrachloroethane, PCBs, and phenol) are provided in
Appendix E. Post-RI loading data for the following discharges are included
in Appendix E:
• Wasser/Winters log sorting yard drainage ditches HY-724-01,
HY-724-02, and HY-043 (Sweet-Edwards & Associates et al.
1987)
• Pennwalt groundwater loading (Hart-Crowser & Associates 1986).
Recent groundwater loading information regarding the Pennwalt Chemical
Corporation (Kennedy/Jenks/Chilton 1987a) and data from recent investigations
at several of the log sorting yards (Ecology and Environment 1987; CH2M HILL
1987; and ERT 1987) have not been included in Appendix E. The following is
a summary of available loading information for the contaminants of concern
by contaminant source.
Pennwalt Chemical Corporation—Pennwalt's NPDES permit contains maximum
daily average discharge limits for copper, lead, and nickel of 1.5, 0.45,
and 0.86 kg/day, respectively. As mentioned previously, the copper limita-
tion has been violated on several occasions. Kennedy/Jenks/Chilton (1987a)
reported a groundwater loading of arsenic to the waterway of 52 Ib/day.
This is considerably higher than the loading presented in Hart-Crowser &
Associates (1986), since the aquifer parameters used to calculate the
discharge have been refined.
For the Wasser/Winters log sorting yard, Ecology (Norton, D., 10 Novem-
ber 1987, personal communication) estimated that loading of total arsenic
from groundwater is approximately 1-12 percent as great as the annual
average surface water loading (Norton and Johnson 1985a; see also Appen-
dix E). Groundwater input was estimated from contaminant concentrations
reported by Ecology and Environment (1987) and a flow rate calculated from
the aquifer parameters reported by Ecology and Environment (1987). Surface
water loading reported by Sweet-Edwards & Associates et al. (1987) for the
same site is 6.4 Ib total arsenic (5.1 Ib dissolved), based on a 25-h storm
in which 1.4 in of precipitation was recorded. That value is similar to the
surface water loading of 4.4 Ib/day total arsenic reported by Norton and
Johnson (1985a) for storm conditions.
For the Louisiana Pacific site, a surface water loading of 0.17 Ib/day
total arsenic (with 81 percent soluble) was reported in CH2M HILL (1987).
This estimate was based on data obtained from six sampling events and
represents a weighted average of storm and non-storm flow. Arsenic loadings
measured during two storm events by Norton and Johnson (1985a) averaqed
0.74 Ib/day.
A dry-weather surface water loading of 0.016 Ib/day total arsenic was
reported for the 3009 Taylor Way site based on one sampling event (ERT
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1987). This value is much lower than that presented in Norton and Johnson
(1985a) where an average daily surface water loading of 0.49 Ib/day total
arsenic was reported. However, this value represents a weighted average of
storm and nonstorm loadings.
Kaiser Ditch—The average concentration of arsenic in effluent from the
Kaiser Ditch based on 10 measurements is 41 ug/L (see Appendix E) which ,is
well above average urban runoff concentration (residential and highway) for
arsenic reported by Metro (Stuart et al. 1988). The calculated average
surface water loading of arsenic to the head of Hylebos Waterway reported in
Appendix E is 0.65 Ib/day based on eight observations. No information is
available for loadings of PCBs or HPAH from Kaiser Ditch to the head of
Hylebos Waterway.
Ecology collected sediment from the Kaiser Ditch June 1987. Results
from this study (Norton, D.f 15 April 1988, personal communication) indicate
that arsenic in the sediment is elevated somewhat (1.8 times) over the
cleanup goal of 57 mg/kg. HPAH and PCBs were measured at concentrations of
6 and 3.3 times the long-term cleanup goals of 17,000 ug/kg and 150 ug/kg,
respectively. The comparison of drainage ditch sediment with cleanup goals
assumes no mixing of sediment with cleaner material from other sources.
Such comparisons provide a worst-case analysis of the impact of drainage
ditch discharge on waterway sediment quality.
East Channel Ditch—The concentrations of metals in effluent from the
East Channel Ditch reported in Appendix E are among the highest measured in
sources to the head of Hylebos Waterway. The average concentration of
arsenic in effluent from the East Channel Ditch is 14,740 ug/L (see
Appendix E) which is well above average urban runoff concentration (resi-
dential and highway) for arsenic reported by Metro (Stuart et al. 1988).
The average calculated loading to the head of Hylebos Waterway reported in
Appendix E is 0.68 Ib/day based on six measurements.
Morninoside Ditch—Average concentrations of metals in effluent from
Morningside Ditch are similar to those reported for urban runoff (residential
and highway) by Metro (Stuart et al. 1988). The average calculated arsenic
loading reported in Appendix E is 0.0045 Ib/day (seven measurements).
Ecology collected sediment from Morningside Ditch in June 1987.
Results from this study (Norton, D., 15 April 1988, personal communication)
indicate that sediment arsenic concentrations are 5.5 times as great as the
long-term cleanup goal of 57 mg/kg. Measured HPAH concentrations were well
below the corresponding long-term cleanup goal, indicating that Morningside
Ditch is not a significant source of this class of compounds. Measured PCB
concentrations were 6.3 times as great as the 150 ug/kg long-term cleanup
goal. By ignoring mixing with cleaner sediment from other sources, such
comparisons provide a worst-case analysis of the impact of drainage ditch
sediment or waterway sediment quality.
5-30
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5.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the effects of source control and natural
recovery processes were evaluated based on contaminant concentrations in the
sediment and assumptions regarding the relationship between sources and
sediment contamination. Included within the evaluation was an estimate of
the degree of source control needed to maintain acceptable sediment quality
over the long term.
5.3.1 Feasibility of Source Control
In this section, sources of contamination are summarized; available
control technologies are identified; and contaminant reductions technically
achievable through the use of all known, available, and reasonable tech-
nologies are estimated.
Seven major potential problem sources have been identified at the head
of Hylebos Waterway: Kaiser Aluminum and Chemical Corporation's plant
(PAH); Pennwalt Chemical Corporation's plant (various chemicals); General
Metals of Tacoma, Inc.'s scrap metal recycling operation (metals and
potentially PCBs); seven log sorting yards (metals); the East Channel,
Morningside, and Kaiser ditches (various chemicals); the landfill operated
by B&L Trucking (metals); and Tacoma Boatbuilding Company (metals). Three
of the log sorting yards and B&L landfill have ceased operations (no
additional controls are recommended for the U.S. Gypsum facility). Source
controls have been implemented or may be required for the following
mechanisms of contaminant discharge:
• Process effluents (Pennwalt)
• Storm drains and ditches (Kaiser, East Channel, and Morning-
side Ditches)
• Surface water runoff (Kaiser sludge deposits, Pennwalt, log
sorting yards, General Metals, Tacoma Boatbuilding Company)
• Groundwater seeps and infiltration (Kaiser sludge deposits,
Pennwalt, log sorting yards, General Metals, B&L landfill
leachate)
• Air emissions (Kaiser facility; the need for air emission
controls has not been established and is not considered here).
The level of source control assumed to be feasible for the major sources is
noted in Table 5-2.
5-31
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TABLE 5-2. EFFECTIVENESS OF SOURCE CONTROL FOR HEAD OF HYLEBOS WATERWAV
Problem Area
Frequency of Detection*
1%)
As HPAH PCB
Estimated Average
Annual Discharge
(10b gal/yr)
Average Load3
db/day)
Estimated Source
Control
Rationale for Percent Source Control
Kaiser Aluminum
Process water
Surface water
(HK-052)
90
33
212-361°
30
U.S. Gypsum
Landfill
I B&L Landfill
Co
ro
Surface water 100
Groundwater 100
Pennwalt
Process water 100
(HY-058)
0.2
10
Unknown
Groundwater
96
4,700
339
Unknown
0.65 As
<0.15 HPAH
HPAH-90
As-90
Unknown
90
4.6-5.4 mg/Ld
0.15-38 mg/Le
90
90
3.9
0.6-11
529
95
95
Wet scubber sludges identified as main HPAH source.
Surface runoff from plant area has been relocated around sludge
areas to minimize contact. Sludge management plan involves
consolidating sludge into one impoundment with an impermeable
layer, and monitoring groundwater
Tide gate installed at mouth of Kaiser Ditch.
NPDES-permitted discharge routed through settling basin prior
to discharge to Kaiser Ditch.
Surface water controls assumed to be implemented at log sorting
yards in HK-052 basin to reduce As loading.
Landfill inactive since 1979.
Fill and underlying contaminated soils excavated to level where
EP toxicity concentration for As dropped below target level
of 0.5 mg/kg.
Site paved and is now a parking lot.
Landfill inactive since 1985, partial capping of fill completed
(1985-1987).
Ecology is pursuing site cleanup under the State Superfund Law
(70:1058). Eleven-month RI/FS will begin in December 1988.
Ecology is hiring a contractor to prepare a site stabilization plan
to control contaminated leachate. Plan to control groundwater
contamination assumed to be implemented.
Source of As discharge for plant outfall was identified and miti-
gated by Pennwalt in 1986.
Pennwalt predicts reduction in As loading from 52 Ib/day to
0.1 Ib/day as a result of recommended As mitigation plan,
which involves construction of a groundwater containment
barrier, surface capping, and groundwater monitoring.'
Storm drains 100 HY-709:
(HY-056, HY-708. 50
HY-709)
70
8.6 As As-80 Surface runoff from plant area routed through plant treatment
system (pH neutralization) in 1981.
As loading to waterway decreased by 75-95 percent.
-------
I ABLE 5-2. (Continued)
Frequency of Detection3
Problem Area As HPAH PCB
Estimated Average
Annual Discharge
(10b gal/yr)
Average Load
(Ib/day)
Estimated Source
Control
Rationale for Percent Source Control
General metals
Unknown HY-34 drain
sediments (ug/kg)
11-31.000
#2-21,000
#3-23,000
#4-21,000
70 Inactive PCB transformers removed in September 1987 under admini-
strative order.
Work plan for RI/FS study expected to be completed by February 1988.
Remediation of site assumed.
Log sorting yards
Surface water 100
Groundwater 78
tn
I
U>
Co Storm drains
HY-054, HM-028 100
90
Unknown
140
5.9
Cascade #2;
Wasser/Winter:
0.018-
0.22 mg/Ld
0.7
90 Four of five log sorting yards in basin are currently inactive.
remaining yard (Weyerhaeuser) is paved. Implementation of
surface water controls was assumed.
80 Same as above. Implementation of groundwater controls was assumed.
90 Loading is primarily from HY-054 which drains portion of Dunlap
Towing log sorting yard (currently inactive). Consent Decree has
been formalized. Focused FS is under Ecology review. Implemen-
tation of surface water controls was assumed.
Hylebos Creek
(HC-000)
67
5,900
2.4
60 Available data indicate that elevated As concentrations caused by
leachate from B&L landfill, U.S. Gypsum landfill in upper basin,
and log sorting yards in lower basin. Remediation of these
three sources was assumed.
Removal of contaminated streambed sediments found downstream of
landfills was assumed.*"
Other storm
drains
100
120
HY-043+HY-055: 60
1.0
Drains HY-043 and HY-055 serve portions of log sorting yards.
Construction of surface water controls at log sort yards was
assumed.
Control of other As sources (slag-related) in basin was not
assumed.
* Tetra Tech (1987c).
" +=Documented historical contamination. Not quantifiable.
c Davies, D., 10 June 1988, personal communication.
d Johnson and Norton (1985b).
e Ecology & Environment (1987).
' Hart-Crowser & Associates (1986).
9 Kennedy/Jenks/Chilton (1987a).
h Stinson et al. (1987).
-------
Technologies for reducing contaminants in process effluents include
primary and secondary wastewater treatment, outfall relocation, and in-plant
contaminant reduction through process changes or product substitution.
Available technologies for controlling migration of contaminants via
groundwater are summarized in Section 3.2.1. General categories include
removal or treatment of the contaminant source, containment (e.g., slurry
walls), collection, in situ treatment, and post-removal treatment.
Available technologies for controlling surface water runoff are
summarized in Section 3.2.2. These technologies include methods for
retaining runoff onsite (e.g., berms, channels, grading, sumps), revegetation
or capping to reduce erosion of waste materials, and removal or treatment of
contaminated material.
Methods for treating storm water after collection in a drainage system
also exist. Sedimentation basins and vegetation channels (or grassy
swales) have been shown to effectively remove contamination associated with
particulate matter. Removals of up to 75 percent and 99 percent for total
suspended solids and lead, respectively have been reported for detention
basins (Horner and Wonacott 1985; Finnemore and Lynard 1982). Removals of
90 percent for lead, copper, and zinc and 80 percent for total suspended
solids have been achieved using grassy swales (Horner and Wonacott 1985;
Miller 1987). Water containing both particle-bound and soluble metals can
be treated by conventional coagulation. Effectiveness varies depending on
water characteristics (speciation is particularly important for arsenic).
However, removals of 80-95 percent are attainable for arsenic (James M.
Montgomery, Consulting Engineers, Inc. 1985).
Conclusion--
Implementation of appropriate measures to control contaminant inputs
to the head of Hylebos Waterway via process wastewater, surface water, and
groundwater should result in significant reductions in contaminant dischar-
ges. Given the contaminant types, multiplicity of sources, and available
control technologies, it is estimated that implementation of all known,
available, and reasonable control technologies will reduce contaminant
loadings by up to 70, 80, and 90 percent for the indicator chemicals PCBs,
arsenic, and HPAH, respectively. The relatively higher percentage of source
control assumed feasible for HPAH results from the presence of fewer HPAH
sources. Sources of PCBs have not been fully identified, and a lower degree
of source control (70 percent) is assumed feasible.
5.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals PCBs, arsenic, and HPAH. Results are
reported in full in (Tetra Tech 1987a). A summary of those results is
presented in this section.
5-34
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The depositional environment at the head of Hylebos Waterway can be
reasonably well-characterized by a sedimentation rate of 990 mg/cm^/yr
(0.77 cm/yr) and a mixing depth of 10 cm. Losses due to biodegradation and
diffusion for the indicator chemicals were determined to be negligible. Two
timeframes for sediment recovery were considered: a reasonable timeframe
(defined as 10 yr) and the long term.
Source loadings for all three indicator chemicals in the head of Hylebos
Waterway are assumed to be in steady-state with sediment accumulation for the
purpose of establishing the relationship between source control and sediment
recovery. This assumption is environmentally protective in that sediment
profiles suggest a trend toward decreasing contaminant loading. Results of
the sediment recovery evaluation are summarized in Table 5-3.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times are predicted to
be 35 yr for PCBs, 19 yr for arsenic, and 10 yr for HPAH. These predictions
are based on the highest concentrations of the indicator chemicals measured
in the problem area. Sediment recovery in the 10-yr timeframe is predicted
to be possible only for HPAH under conditions of complete source elimination.
Sediment recovery is not predicted to be possible in the 10-yr timeframe for
PCBs or arsenic. Minimal reductions in sediment concentrations are predicted
unless sources are controlled.
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source control
is expected to reduce source inputs by 70 percent for PCBs, 80 percent for
arsenic, and 90 percent for HPAH. With this level of source control as an
input value, the model predicts that sediments with enrichment ratios of
1.6 for PCBs (i.e., PCB concentrations of 240 ug/kg dry weight), 1.7 for
arsenic (i.e., arsenic concentrations of 97 mg/kg dry weight), and 1.9 for
HPAH (i.e., HPAH concentrations of 32,130 ug/kg dry weight) will recover to
the long-term cleanup goal within 10 yr (Table 5-3). These estimates are
based on the average of the three highest concentrations measured in the
problem area for each indicator chemical. The surface area of sediments not
expected to recover to long-term cleanup goals is shown in Figure 5-8. For
comparison, sediments currently exceeding long-term cleanup goals for
indicator chemicals are also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that 89 percent of the PCBs, 70 percent of the
arsenic, and 47 percent of the HPAH inputs must be eliminated to maintain
acceptable contaminant concentrations in freshly deposited sediments
(Table 5-3). These estimates are based on the average of the three highest
sediment concentrations measured for each indicator chemical in the problem
area.
5-35
-------
TABLE 5-3. HEAD OF HYLEBOS WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
PCBs Arsenic HPAH
Station with Hiahest Concentration
Station identification
Concentration3
Enrichment ratio''
Recovery time if sources are
eliminated (yr)
Percent source control required
to achieve 10-yr recovery
Percent source control required
to achieve long-term recovery
Averaae of Three Hiahest Stations
Concentration3
Enrichment ratio"
Percent source control required
to achieve long-term recovery
10-Yr Recovery
Percent source control assumed
feasible
Highest concentration recovering
in 10 yra
Highest enrichment ratio of sediment
recovering in 10 yr
HY-22
2,000
13.3
35
NPc
93
1,340
8.9
89
70
240
1.6
HI
203
3.6
19
NPc
72
190
3.3
70
80
97
1.7
HY-16
34,280
2.0
10
100
50
31,855
1.9
47
90
32,130
1.9
a Concentrations in ug/kg dry weight for organics, mg/kg dry weight for
metals.
" Enrichment ratio is the ratio of observed concentration to cleanup goal.
c NP = Not possible.
5-36
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AT PRESENT
in
i
to
IN10YR
Head of Hylebos Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA(yd2)
VOLUME (yd3)
IN 10 YR
DEPTH (yd)
AREA(yd2)
VOLUME (yd3)
1
381,000
381,000
1
217,000
217,000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
PCB(AET=150ng/kg)
HPAH (AET = 17,000 ng/kg)
ARSENIC (AET = 57 mg/kg)
Figure 5-8. Sediments at the head of Hylebos Waterway not meeting cleanup goals for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
These values are presented for comparative purposes; the actual
percent reduction in source loading is subject to the uncertainty inherent
in the predictive model. These ranges may represent upper limit estimates
of source control requirements, since the assumptions incorporated into the
model are considered to be environmentally protective. This may be
particularly true for PCBs since the sources appear to be largely historic.
For comparison with source control estimates derived using the
mathematical model, the required percent reductions of indicator chemicals in
sediment from the Kaiser and Morningside Ditches were calculated. Kaiser
Ditch sediment data indicate that reduction of 84, 16, and 72 percent would
be required for PCBs, arsenic, and HPAH, respectively to maintain adequate
sediment quality. For sediment from Morningside Ditch, reductions of 75, 85,
and 0 percent would be required. This comparison is conservative and assumes
no mixing of incoming sediments with cleaner material from other sediment
sources.
5.3.3 Source Control Summary
The major identified known or potential sources of problem chemicals to
the head of Hylebos Waterway include Pennwalt Chemical Corporation, General
Metals, Inc., log sorting yards, storm drains/ditches, Kaiser Aluminum, and
Tacoma Boatbuilding Company. If these sources are completely eliminated,
then it is predicted that sediment concentrations of the indicator chemicals
in the surface mixed layer will decline to the long-term cleanup goal of
150 ug/kg for PCBs in approximately 35 yr, to 57 mg/kg for arsenic in 19 yr,
and to 17,000 ug/kg for HPAH in approximately 10 yr. Sediment remedial
action will therefore be required to mitigate the observed and potential
adverse biological effects associated with sediment contamination within a
reasonable timeframe.
Prior to initiating sediment remedial actions, additional source
control measures will be needed to ensure that acceptable sediment quality
is maintained. The estimated percent reduction required for long-term
maintenance is 89 percent for PCBs, 70 percent for arsenic, and 47 percent
for HPAH, based on the average of the three highest observed concentrations
for the three indicator chemicals. Implementation of all known, available,
and reasonable control technologies are expected to provide approximately
70, 80, and 90 percent reductions in PCBs, arsenic, and HPAH, respectively.
Comparison of required reductions to maintain acceptable sediment quality
with estimated feasible levels of source control suggests that acceptable
sediment quality can be maintained for arsenic and HPAH (see Table 5-3).
However, the percent source control required to maintain acceptable levels
of PCBs in sediments is approximately 20 percent greater than that estimated
to be feasible. The former estimate was based on the three stations
exhibiting the highest levels of contamination in the waterway, specifically
in the vicinity of the Pennwalt facility. Using an average of all PCB
concentrations exceeding the long-term cleanup goal of 150 ug/kg in the
problem area, the required source reduction would-be reduced to approximately
70 percent. This provides an illustration of the uncertainty related to the
estimates of required source control based on measured sediment concen-
trations and confirms that the approach taken is environmentally protective.
5-38
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5.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with PCBs, arsenic, and HPAH
concentrations exceeding long-term cleanup goals is approximately 381,000 ydj
(see Figure 5-8). This volume was estimated by multiplying the area! extent
of sediment exceeding the long-term cleanup goal (381,000 ydO by 1.0 yd,
the estimated depth of contamination (see contaminant sediment profiles in
Figures 5-2, 5-3, and 5-4). The estimated thickness of contamination is
only an approximation; few sediment profiles were taken and the vertical
resolution of those profiles was poor at the depth of the contaminated
horizon. For the volume calculations, depths were slightly overestimated.
This conservative approach was taken to reflect the fact that depth to the
contaminated horizon cannot be accurately dredged, to account for dredge
techniques tolerances, and to account for uncertainties in sediment quality
at locations between sediment profile sampling stations.
The total volume of sediments with PCBs, arsenic, and HPAH chemical
concentrations that are expected to exceed long-term cleanup goals 10 yr
following implementation of all known, available, and reasonable control
technologies is approximately 217,000 yd3. This volume was estimated by
multiplying the areal extent of sediment contamination with enrichment
ratios greater than 1.6 for PCBs, 1.7 for arsenic, and 1.9 for HPAH (see
Table 5-3) by the estimated 1.0 yd depth of contamination. Remedial
alternatives were evaluated using 217,000 yd3 as the volume of sediment
requiring remediation.
5.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
5.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion, this set of alternatives is
evaluated to determine the suitability of each alternative for the remedi-
ation of contaminated sediments in the head of Hylebos Waterway. Remedial
measures address contaminated sediments that are predicted to exceed cleanup
goals 10 yr after implementing feasible source controls and allowing natural
recovery processes to occur. The objective of this evaluation is to
identify the alternative considered preferable to all others based on
CERCLA/SARA criteria of effectiveness, implementability, and cost using
available data.
The first step in this process is to assess the applicability of each
alternative to remediation of contaminated sediments in the head of Hylebos
Waterway. Site-specific characteristics that must be considered in such an
assessment include the nature and extent of contamination; the environmental
setting; and site physical properties such as waterway usage, bathymetry..
and water flow conditions. Alternatives that are determined to be appro-
priate for the waterway can then be evaluated based on the criteria discussed
in Chapter 4.
5-39
-------
Selection of remedial alternatives for this problem area is complicated
by the presence of a complex contaminant matrix comprised of both organic
and inorganic contaminants. The Pennwalt facility has been identified as a
source of inorganic contaminants (primarily arsenic) and HPAH to the
waterway. Kaiser Aluminum has been identified as a major source of HPAH to
the problem area. The General Metals facility has been associated with
possible PCBs and metals inputs. The log sorting yards have been identified
as another source of inorganic contaminants to the sediments. The storm
drains and ditches that discharge to the waterway have been identified as
sources of HPAH, metals, and PCBs (see Section 5.2). Areal distributions
for all three indicators are presented in Figure 5-8 to indicate the degree
to which contaminant groups overlap based on long-term cleanup goals and
estimated 10-yr sediment recovery.
The relatively high organic content of sediments in the head of Hylebos
Waterway, in conjunction with extensive PCBs and HPAH contamination, suggests
that treatment processes for organics might be technically feasible. The
solvent extraction process is expected to be highly effective in removing
PCBs and HPAH from problem area sediments. In addition, this process has
been shown to be effective in precipitating inorganic contaminants from
wastes in a nonleachable form (Austin, D., 22 January 1988, personal
communication). Incineration of the organic contaminants should also
provide an effective treatment system for the organic problem chemicals
present. The presence of metals at concentrations ranging as high as
3,500 mg/kg (a zinc value derived from a station near the head of the
waterway) may require that additional engineering controls for particulate
emissions be incorporated as part of the incineration process.
The land treatment alternative has been eliminated from consideration
based on the large volume of sediment requiring remediation and uncertainties
regarding the effectiveness of the process for materials containing PCBs in
a complex organic matrix. Solidification alone is also unlikely to be
successful because of the high concentrations of total organic carbon
(greater than 10 percent throughout the central portions of the problem
area) and other organic contaminants, and is therefore not evaluated.
The need for periodic dredging to maintain channel depth precludes the
use of in situ capping within the channel boundaries. The potential that
future dredging, will be needed to deepen the waterway for deeper draft
vessels would also compromise the effectiveness of a cap in the adjacent
shoreline areas.
Evaluation of the no-action alternative is required by the NCP to
provide a baseline against which other remedial alternatives can be
compared. The institutional controls alternative, which is intended to
protect the public from exposure to contaminated sediments without implemen-
ting sediment mitigation, provides a second baseline for comparison. The
three nontreatment dredging and disposal alternatives are applicable to
remediation of contaminated sediments in the head of Hylebos Waterway. The
5-40
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following seven sediment remedial alternatives are evaluated in this section
for the cleanup of the head of Hylebos Waterway:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solvent extraction/upland disposal
• Clamshell dredging/incineration/upland disposal.
5.5.2 Evaluation of Candidate Alternatives
The three primary evaluation criteria are effectiveness, implement-
ability, and cost. A narrative matrix summarizing the assessment of each
alternative based on effectiveness and implementability is presented in
Table 5-4. A comparative evaluation of alternatives based on ratings of
high, moderate, and low in the seven subcategories of evaluation criteria is
presented in Table 5-5. As discussed in Chapter 4, for effectiveness these
subcategories are short-term protectiveness; timeliness; long-term protec-
tiveness; and reduction in toxicity, mobility, or volume. The implemen-
tability subcategories are technical feasibility, institutional feasibility,
and availability. Capital and O&M costs are also presented in Table 5-5.
Remedial costs are shown for two sediment cleanup scenarios. The "long-term
cleanup goal cost" presented refers to the costs associated with remediation
of all sediments with concentrations currently exceeding the long-term
cleanup goal. The "long-term cleanup goal 10-yr recovery cost" refers to the
costs associated with remediation of sediments that are expected to exceed
the cleanup goal 10 yr after implementing source controls and allowing
natural recovery to occur (i.e., the volume requiring remediation described
at the end of Section 5.4).
Short-Term Protectiveness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
biological and potential public health impacts would continue with the
contaminated sediments remaining in place. Source control measures initiated
is part of the institutional controls would tend to reduce sediment
•>ntamination with time, but adverse impacts would persist in the interim.
The clamshell dredging/nearshore disposal alternative is rated moderate
short-term protectiveness primarily because nearshore intertidal habitat
d be lost in siting the disposal facility. While the loss of habitat
v,o nearshore site development in Commencement Bay may be mitigated by
"ing habitat enhancement in a nearby area, the availability of sites
5-41
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EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
LONG-TERM PROTECTIVENESS
(CONTAMINANT
1 MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 5-4. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE HEAD OF HYLEBOS WATERWAY PROBLEM AREA
NO ACTION
NA
NA
Original contamination remains.
Source inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative is ranked
seventh overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food species remains.
Original contamination remains.
Source Inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxicity and contam-
inant mobilty are expected to
remain at current levels or
increase as a result of continued
source inputs. Contaminated
sediment volume increases as
a result of continued source
inputs.
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
There are no elements of Insti-
tutional control measures that
have the potential to cause
harm during implementation.
Source control is implemented
and would reduce sediment
contamination with time, but
adverse impacts would persist
in the interim.
Access restrictions and mon-
itoring efforts can be implemented
quickly. Partial sediment
recovery is achieved naturally,
but significant contaminant levels
persist. Natural recovery ranges
from 10 to 36 years. This
alternative is ranked sixth over-
all for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Removal with dredge
and disposal with downpipe ami
diffuser minimizes handling re-
quirements. Workers wear pro-
tective gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment is resuspended during
dredging operations. Short-term
benthic habitat impacts at the
disposal site.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
Waterway shipping needs delay
project completion. This alter-
native is ranked second over-
all for timeliness.
The long-term reliability of the
cap to prevent contaminant re-
exposure in the absence of
physical disruption is good.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota. Protection is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment.
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in
situ conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremediaSon
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM to a barge offshore during
dredging and disposal. Public
access to dredge and disposal
sites is restricted. Public ex-
posure potential is low.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Workers wear pro-
tective gear.
Existing contaminated habitat
Is destroyed. Nearshore inter-
tidal habitat is lost. Contami-
nated sediment is resuspended
Dredge water can be managed
to prevent release of soluble
contaminants.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment and methods are available.
Disposal siting issues should no
cause any delays. This alterna-
tive is ranked first for timeliness
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM.
Varying physicochemical con-
ditions in the fill may increase
potential for contaminant migra-
tion over CAD.
The confinement system reduces
the potential for environmental
exposure to contaminated sedi-
ment. The potential for contami-
nant migration into marine envir-
onment may increase over CAD.
Physicochemical changes could
be minimized by placing sedi-
ments below low tide elevation.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. Altered
conditions resulting from
dredge/disposal operations
may increase mobility of metals.
Volume of contaminated sedi-
ments is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM Is confined to a pipeline
during transport. Public access
to dredge and disposal sites is
restricted. Exposure from COM
spills or mishandling is possible
but overall potential is low.
Hydraulic dredging confines
COM to a pipeline during trans-
port Dredge water contamina-
tion may increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment is resuspended during
dredging operations. Dredge
water can be managed to pre-
vent release of soluble contami-
nants.
Approvals and construction are
estimated to require a minimum
of 1 to 2 years. Equipment and
methods used require no devel-
opment period. Pre-implementa-
tion testing is not expected to
be extensive. This alternative
is ranked third overall for time-
liness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM. Al-
though the potential for ground-
water contamination exists, it is
minimal. Upland disposal facil-
ities are more secure than near-
shore facilities.
Upland disposal is secure, with
minimal potential for environ-
mental impact if property de-
signed. Potential for ground-
water contamination exists.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may increase due to resuspen-
sion of sediment
CLAMSHELL DREDGE/
SOLVENT EXTRACTION
UPLAND DISPOSAL
Public access to dredge, treat-
ment and disposal sites is re-
stricted. Extended duration of
treatment operations may resul
in moderate exposure potential
Additional COM handling asso-
ciated with treating dredged
material Increases worker risk
significantly over dredge/dis-
posal options. Workers wear
protective gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment is resuspended during
dredging operations.
Bench and pilot scale tasting
are required for the solvent ex-
traction process. Full scale
equipment is available. Remed-
iation could be accomplished
within 2 to 3 years. This alter-
native is ranked fourth overall
for timeliness.
Treated COM may be used as
inert construction material or
disposed of at a municipal or
demolition solid waste landfill.
Testing required to determine
disposition of treatment resid-
uals. Treatment effectively
destroys or contains contami-
nants.
Harmful organic contaminants
are removed from COM. Perma-
nent treatment for organic con-
taminants is effected and in-
organic contaminants are iso-
lated by incineration of concen-
trated organic residue and in-
organic solidification.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal. Residual
inorganic contaminants are
solidified.
Harmful contaminants are re-
moved from COM. Concen-
trated organic contaminants are
disposed of by RCRA- approved
treatment or disposal. Toxicity
and mobility considerations are
eliminated by extraction followed
by incineration or solidification.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment and disposal sites is re-
stricted. Extended duration of
treatment operations may result
In moderate exposure potential.
Incineration of COM Is accom-
plished over an extended period
of time requiring temporary
storage thereby Increasing ex-
posure risks. Additional treat-
ment process Increases
hazards. Workers wear pro-
tective gear.
Existing contaminated habitat
Js destroyed by dredging. Sedi-
ment is resuspended during
dredging operations. Process
controls are required to reduce
potential air emissions.
Substantial COM testing and
Incinerator installation time are
required before a thermal treat-
ment can be implemented. Re-
mediation could be accomplish-
ed within 2 to 3 years. This al-
ternative is ranked fifth overall
for timeliness.
Treated COM may be used as
inert construction material or
disposed of at a municipal solid
waste landfill. Testing required
to determine disposition of treat-
ment residuals. Treatment
effectively destroys or contains
contaminants.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals is effectively treated by
encapsulation.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous.
COM containing low levels of
Inorganic contaminants may be
rendered nonhazardous.
5-42
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IMPLEMENTABILITY
TECHNICAL FEASIBILITY
INSTITUTIONAL FEASIBILTY
1 AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 5-4. (CONTINUED)
NO ACTION
Implementation ot this alterna-
tive is feasible and reliable.
No monitoring over and above
programs established under
ottier authorities is implemented.
There are no O 4 M requirements
associated with the no action
alternative.
This alternative is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet trie intent of CERCLA/
SARA and NCP because of on-
going impacts.
All materials and procedures are
available.
INSTITUTIONAL
CONTROLS
Source control and institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily implemented.
Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
Some O & M is associated with
monitoring, maintenance of
warning signs, and issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels in sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
impacts. State requirements
for source control are achieved.
Coordination with TPCHD for
health advisories for seafood
consumption is required.
All materials and procedures are
available to implement institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment
is reliable. Placement of dredge
and capping materials difficult,
although feasible. Inherent dif-
ficulty in placing dredge and
capping materials at depths of
100 ft or greater.
Confinement reduces monitoring
requirements in comparison to
Institutional controls. Sediment
monitoring schemes can be
readily implemented.
O & M requirements are minimal.
Some O & M is associated with
monitoring for contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desirable
than if COM is treated. '
i
WISHA/OSHA worker protection
is required. Substantive as-
pects of CWA and shoreline
management programs must be
addressed.
Equipment and methods to im-
plement alternative are readily
available. Waterway CAD site
is considered available. Availa-
bility of open water CAD sites is
uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring compared with CAD.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for faci-
lity siting is uncertain but is as-
sumed feasible. However, dis-
posal of untreated COM is con-
sidered less desirable than if
COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been identified
and Is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
is reliable. Upland confinement
technologies are well developed.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring over CAD. Installa-
tion of monitoring systems is
routine aspect of facility siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Coordination is required for
establishing discharge criteria
for dredge water maintenance.
However, disposal of untreated
CDM is considered less desir-
able than if CDM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLVENT EXTRACTION/
UPLAND DISPOSAL
Although still in the development
stages, sludges, soils, and sedi-
ments have successfully been
treated using this technology.
Monitoring Is required only to
evaluate the reestabllshment
of benthlc communities. Moni-
toring programs can be readily
Implemented.
No O & M costs are Incurred at
the conclusion of CDM treat-
ment. System maintenance is
Intensive during implementation.
Approvals depend largely on re-
sults of pilot testing for extrac-
tion and solidification and the
nature of treatment residuals.
WISHA/OSHA worker protection
required. Section 404 oermit is
required. Alternative complies
with U.S. EPA's policies for on-
site disposal and permanent re-
duction in contaminant mobility.
Requires RCRA permit for dis-
posal of concentrated organic
waste.
Process equipment is available
in developmental stages. Dis-
posal site availability is not a
primary concern because of re-
duction in hazardous nature of
material.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Incineration systems capable of
handling CDM have been de-
veloped, but no applications in-
volving CDM have been report-
ed. Effects of salt and moisture
content must be evaluated.
Disposal site monitoring is not
required if treated CDM Is deter-
mined to be nonhazardous. Air
quality monitoring Is intensive
during Implementation.
No O & M costs are Incurred at
the conclusion of CDM treat-
ment System maintenance is
intensive during implementation.
Approvals for incinerator opera-
tion depend on pilot testing and
ability to meet air quality stan-
dards.
WISHA/OSHA worker protection
required. Section 404 permit is
required. Alternative complies
with U.S. EPA's policies for on-
site disposal and permanent re-
duction in contaminant toxicity
and mobility. Requires compli-
ance with PSAPCA standards.
Incineration equipment can be
installed onsite for CDM re-
mediation efforts. Applicable
incinerators exist Disposal site
availability is not a concern be-
cause of reduction in hazardous
nature of material.
5-43
-------
TABLE 5-5. EVALUATION SUMMARY FOR HEAD OF HYLEBOS WATERWAY
No Action
Short-Term
Protectiveness Low
Timeliness Low
Long-Term
Protectiveness Low
Reduction in Toxicity,
Mobility, or Volume Low
Technical Feasibility High
Institutional
1 Feasibility Low
"** Availability High
Long-Term Cleanup
Goal Cost3
Capital
O&M
Total
Long-Tertn Cleanup
Goal with 10-yr
Recovery Cost
Capital
O&M
Total
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
2,325
2,331
6
2,325
2,331
Clamshell/
CAD
High
Moderate
High
Low
Moderate
Moderate
Moderate
3,016
481
3,497
1.731
376
2,107
Clamshell/
Nearshore
Disposal
Moderate
High
Moderate
Low
High
Moderate
High
9,350
558
9,908
5.338
421
5.759
Hydraulic/
Upland
Disposal
High
Moderate
Moderate
Low
High
Moderate
Moderate
16,685
823
17,508
9,503
572
10,075
Clamshell/
Extraction/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
80,533
787
81,320
45,880
551
46.431
Clamshell/
Incinerate/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
183,060
787
183,847
104,275
551
104,826
a All costs are in $1,000.
-------
with potential for habitat enhancement is limited. The confinement of
contaminated dredged material to a barge offshore during dredging and
disposal and the availability of means for adequately protecting both the
public and workers during implementation aids in minimizing human health
hazards. Alternatives involving treatment also received moderate ratings for
short-term protectiveness because all involve additional dredged material
handling, longer implementation periods, and increased air emissions, which
potentially increase worker and public exposure.
The clamshell dredging/confined aquatic disposal and hydraulic
dredging/upland disposal alternatives are rated high for short-term
protectiveness because worker and public exposure potentials are minimized,
and because the habitats that are compromised for disposal are of relatively
low sensitivity. The confinement of contaminated dredged material in the
subaquatic environment at a designated disposal site outside the waterway,
using a mechanical dredge for removal and a downpipe and diffuser for
disposal, minimizes handling requirements. Hydraulic dredging with upland
disposal confines contaminated dredged material to a pipeline system through-
out implementation, thereby reducing exposure potentials. If contaminated
dredged material is determined to be unacceptable for disposal at an
existing solid waste landfill, use of a previously unaffected site may be
required. Although this would result in short-term impacts in the upland
environment, the tradeoff of improved waterway habitat and marine produc-
tivity may offset them.
Timeliness--
Because an extensive amount of time is necessary for sediments to
recover naturally, both the no-action and institutional controls alter-
natives are rated low. Source control measures instituted as part of the
institutional controls would tend to reduce contamination with time but
adverse impacts would persist in the interim. Natural recovery times for
the three indicator compounds range from 10 to 35 yr (see Section 5.3.2) if
sources are completely eliminated.
Moderate ratings have been applied to the clamshell dredging/confined
aquatic disposal, hydraulic dredging/upland disposal, clamshell dredging/sol-
vent extraction/upland disposal, and clamshell dredging/incineration/upland
disposal options. For dredging options that involve siting of unused and
undeveloped upland or confined aquatic disposal facilities, approvals and
construction are estimated to require a minimum of 1-2 yr. The equipment
and methods used require no development period, and pre-implementation
testing is not expected to be extensive. Treatment processes may require
additional time for bench-scale testing, pilot burns, and equipment
development or modification. Facility siting and technology development
could be conducted concurrently, however. Once approval is obtained,
treatment of contaminated sediments in the head of Hylebos Waterway will
require a period of approximately 2-3 yr, assuming maximum treatment rates
of 500 yd3/day.
The clamshell dredging/nearshore disposal option is rated high for
timeliness because this alternative can be implemented rapidly with available
5-45
-------
technologies and expertise. Major site development would be required (e.g.,
diking) but can be completed in a relatively short timeframe. Necessary
equipment and methods are readily available, and disposal siting issues are
not likely to delay implementation.
Long-Term Protectiveness--
The comparative evaluations for long-term protectiveness resulted in
low ratings for the no-action and institutional controls alternatives
because the timeframe for natural recovery is long. For the institutional
controls alternative, the potential for exposure to contaminated sediments
would remain, albeit at declining levels following implementation of source
reductions, and the observed adverse biological impacts would continue.
Moderate ratings are assigned for clamshell dredging/nearshore disposal
and hydraulic dredging/upland disposal alternatives because of potential
physicochemical changes due to placing metal-contaminated dredged material
in these disposal facilities. These changes, primarily from new redox
conditions, would tend to increase the migration potential of the metal
contaminants. Leachate testing on dredged sediments indicates that leach-
ability of organic compounds is enhanced under aerobic vs. anaerobic
conditions (U.S. Army Corps of Engineers 1986c). Contaminated dredged
material testing should provide the necessary data on the magnitude of these
impacts. In a nearshore site, physicochemical .changes could be minimized by
placing sediments below the low tide water elevation. Although the
structural reliability of the nearshore facilities is regarded as good, the
nearshore environment is dynamic in nature as a result of wave action and
tidal influences. In addition, the fish mitigation area in the outer Blair
Waterway slip adjacent to,the proposed disposal facility would be regarded
as a sensitive area. The upland disposal facility would be generally
regarded as a more secure option because of improved engineering controls
during construction, but there is potential for impacts on groundwater
resources.
The clamshell dredging/confined aquatic disposal, clamshell dredging/
solvent extraction/upland disposal, and clamshell dredging/incinera-
tion/upland disposal alternatives are rated high for long-term protective-
ness. Placement of material in a confined, quiescent, subaquatic environment
would provide a high degree of isolation, with little potential for exposure
to an environment sensitive to the contaminated dredged material. In
addition, confinement under these circumstances would maintain physicochemi-
cal conditions comparable to in situ conditions, further reducing contaminant
migration potential. The effectiveness of contaminant removal by solvent
extraction and contaminant destruction by incineration substantially
increases the long-term protectiveness of these alternatives over nontreat-
ment dredge and disposal alternatives.
Reduction in Toxicity, Mobility, or Volume-
Low ratings have been assigned to all alternatives under this criterion,
except those involving treatment, which were rated high. Although the
confined aquatic, upland, and nearshore disposal alternatives would isolate
5-46
-------
contaminated dredged material from the surrounding environment, the chemistry
of the material would remain unaltered. For nearshore and upland disposal
alternatives, the mobilization potential for untreated contaminated dredged
material may actually increase with changes in redox potentials. Without
treatment, the toxicity of contaminated sediments would remain at prereme-
diation levels. Contaminated sediment volumes would not be reduced, and may
actually increase with the hydraulic dredging option because the material
would be suspended in an aqueous slurry.
Solvent extraction of contaminated dredged material prior to disposal
would effectively remove organic contaminants, thereby reducing mobilization
potential permanently and significantly for the bulk of the sediments.
Through isolation of contaminants in the extraction residue, this process
would also reduce the volume of contaminants substantially, as compared with
nontreatment alternatives. Because the available data suggest that the
inorganic contaminants are not present at high concentration, the process
may also be relatively effective in extracting these compounds. Performance
tests during bench-scale testing of the extraction process would be expected
to provide sufficient data to substantiate or invalidate these conclusions.
The fate of the residual material and particulates collected during the
incineration process would be contingent upon the results of characterization
analyses. The inorganic contaminant content of the material will largely
determine disposal requirements.
Technical Feasibility--
Clamshell dredging/confined aquatic disposal, clamshell dredging/solvent
extraction/upland disposal, and clamshell dredging/incineration/upland
disposal alternatives have been assigned a moderate rating for technical
feasibility. This rating was applied to the treatment alternatives because
of the need to conduct bench-scale testing and pilot burns prior to
implementation. Technologies for the large-scale treatment of contaminated
dredged material are conceptual at this point, although the methods appear to
be feasible. A moderate rating was also applied to the clamshell dredg-
ing/confined aquatic disposal option. Placement of dredge and capping
materials at depths of approximately 100 ft would be difficult, although
feasible. Considerable effort and resources may be required to monitor the
effectiveness and accuracy of dredging, disposal, and capping operations.
High ratings have been assigned to all other alternatives because the
equipment, technologies, and expertise required for implementation have been
developed and are readily accessible. The technologies constituting these
alternatives have been demonstrated to be reliable and effective elsewhere
for similar operations.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods (e.g., sediment cores, monitoring wells) are
applied for all alternatives. The intensity of the monitoring effort, which
varies with uncertainty about long-term reliability, does not influence the
feasibility of implementation.
5-47
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Institutional Feasibility--
The no-action and institutional controls alternatives have been
assigned low ratings for institutional feasibility because compliance with
CERCLA/SARA mandates would not be not achieved. Requirements for long-term
protection of public health and the environment would not be met by either
alternative.
Moderate ratings have been assigned to the remaining five alternatives
because of potential difficulty in obtaining agency approvals for disposal
sites or implementation of treatment technologies. Although several
potential confined aquatic and upland disposal sites have been identified in
the project area, significant uncertainty remains with the actual construc-
tion and development of the sites. It was assumed that the Blair Waterway
nearshore facility would be available for use. Although excavation and
disposal of untreated, contaminated sediment is discouraged under Section 121
of SARA, properly implemented confinement should meet requirements for
public health and environmental protectiveness. Agency approvals are
assumed to be contingent upon a bench-scale demonstration of the effective-
ness of each alternative in meeting established performance goals (e.g.,
treatability of dredge water, removal of contaminants through extraction).
Availability--
Candidate sediment remedial alternatives that can be implemented using
existing equipment, expertise, and disposal or treatment facilities are
rated high for availability. Because the no-action and institutional
controls alternatives can be implemented immediately, they received a high
rating. A nearshore disposal site was assumed to be available, allowing
rapid implementation of the clamshell dredging/nearshore disposal alterna-
tive. Thus, this alternative also received a high rating for availability.
Remedial alternatives involving dredging with confined aquatic or upland
disposal are rated moderate because of the uncertainty associated with
disposal site availability. Candidate alternatives were developed by
assuming that confined aquatic and upland sites will be available. However,
no sites for contaminated sediments are currently approved for use and no
sites are currently under construction. Depending on the final characteri-
zation of sediments, upland disposal in an existing municipal or demolition
landfill may also be feasible. For costing purposes, development of a RCRA-
equivalent upland site was assumed. A moderate rating has also been
assigned to the alternatives involving treatment because of the same
uncertainties regarding disposal site availability. However, testing
conducted as a part of the bench-scale treatability and performance
evaluation for the treatment processes should confirm that the resulting
product is nonhazardous and appropriate for a standard solid waste management
facility. For costing purposes, disposal in a standard solid waste
management facility was assumed.
5-48
-------
Cost--
Capital costs increase with increasing complexity (i.e., from no action
to the treatment options). This increase reflects the need to site and
construct disposal facilities, develop treatment technologies, and implement
alternatives requiring extensive contaminated dredged material or dredge
water handling. Costs for hydraulic dredging/upland disposal are ap-
proximately 75 percent higher than those for clamshell dredging/nearshore
disposal, primarily because of underdrain and bottom liner installation,
dredge water clarification, and use of two pipeline boosters to facilitate
contaminated dredged material transport to the upland site. The cost of
conducting the treatment alternatives increases as a result of material
costs for the processes, and associated labor costs for material handling and
transport. Incineration costs are high because of the low Btu content of
the sediment and resulting increase in fuel consumption. Dredge water
clarification management costs are also incurred for these options.
A major component of O&M costs is the monitoring requirements associated
with each alternative. The highest monitoring costs are associated with
alternatives involving the greatest degree of uncertainty for long-term
protectiveness (e.g., institutional controls) or where extensive monitoring
programs are required to ensure long-term performance (e.g., confined
aquatic disposal). Costs for monitoring of the confined aquatic disposal
facility are significantly higher because of the need to collect sediment
core samples at multiple stations, with each core being sectioned to provide
an appropriate degree of depth resolution to monitor migration. Nearshore
and upland disposal options, on the other hand, use monitoring well networks
requiring only the collection of a single groundwater sample from each well
to assess contaminant migration.
It was also assumed that the monitoring program will include analyses
for all contaminants of concern (i.e., those exceeding long-term cleanup
goals) in the waterway. This approach is conservative and could be modified
to reflect use of key chemicals to track performance. Monitoring costs
associated with the solidification alternative are significantly lower
because the process results in lower contaminant migration potential.
5.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the seven candidate sediment
remedial alternatives proposed for the head of Hylebos Waterway, clamshell
dredging with nearshore disposal has been recommended as the preferred
alternative for sediment remediation. Because sediment remediation will be
implemented according to a performance-based ROD, the specific technologies
identified in this alternative (i.e., clamshell dredging, nearshore
disposal) may not be the technologies eventually used to conduct the
cleanup. New and possibly more effective technologies available at the time
remedial activities are initiated may replace the alternative that is
currently preferred. However, any new technologies must meet or exceed the
performance criteria (e.g., attainment of specific cleanup criteria)
specified in the ROD. The nearshore disposal alternative is currently
preferred for the following reasons:
5-49
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• The alternative protects public health and the environment by
effectively isolating contaminated sediments in an engineered
disposal facility
• The alternative is consistent with existing plans to fill the
Blair Waterway Slip 1 proposed nearshore fill site
• The nature of the organic contaminants (high molecular
weight, low solubility, and low partitioning potential) is
such that placement below the saturated zone should minimize
migration potential
• The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 401 and 404 of the Clean Water Act,
and other applicable environmental requirements
• Performance monitoring can be accomplished effectively and
implemented readily
• The estimated 217,000-yd^ volume of contaminated sediments is
compatible with the capacity of the proposed nearshore
facility
• Although the cost of this alternative is approximately
$4.3 million less than that of the upland disposal alterna-
tive, it is expected to provide an equivalent degree of public
health and environmental protection
• Although this option is approximately $4 million more than
the confined aquatic disposal option, largely due to the cost
of acquiring nearshore property in the project area, the
additional expenditure is justified since the action can be
implemented more quickly in an available facility that
offers appropriate confinement conditions for the contaminants
of concern.
This alternative is rated high for timeliness, technical feasibility,
and availability because available equipment, resources, and disposal
facilities would be used. The alternative can be implemented quickly with
reliable equipment that has proven effective in past similar operations.
The alternative is rated moderate for short-term protectiveness because
of the loss of intertidal habitat at the disposal site and during dredging
operations in the waterway. This disadvantage can be offset through
incorporation of a habitat replacement project in the remedial process and
replacement of intertidal sediments in the waterway on a one-to-one basis.
The goal of habitat replacement is addressed in part by removal of con-
taminated sediments from the waterway itself and subsequent reestablishment
of that marine habitat. The alternative is also rated moderate for long-
term protectiveness because contaminated sediments would be placed in an
environment subject to wave and tidal influences. In addition, there is
5-50
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potential for long-term impacts to the adjacent fish mitigation area in the
outer slip of Blair Waterway. Contaminants in the head of Hylebos Waterway
have demonstrated relatively high particle affinities (Tetra Tech 1987c),
which would serve to improve long-term containment reliability. Hart-
Crowser & Associates (1985) concluded that monitoring of contaminant
mobility from nearshore disposal sites could be effectively accomplished
with monitoring wells in containment berms for early detection of contaminant
movement. Long-term protectiveness could also be improved with the placement
of slurry walls within the berm (Phillips et al. 1985); however, this
measure has not been included in the cost estimate for this alternative. As
indicated in Table 5-4, this alternative provides a cost-effective means of
sediment mitigation.
Although some sediment resuspension is inherent in dredging operations,
silt curtains and other available engineering controls would be expected to
minimize adverse impacts associated with redistribution of contaminated
dredged material. The effect of dredging on water quality can be predicted
by using data from bench-scale tests to estimate contaminant partitioning to
the water column. Because this alternative can be implemented over a
relatively short timeframe, seasonal restrictions on dredging operations to
protect migrating anadromous fish are not expected to pose a problem.
Dredging activities within this area are consistent with the Tacoma Shoreline
Management Plan and Sections 404 and 401 of the Clean Water Act. Close
coordination with appropriate federal, state, and local regulatory personnel
will be required prior to undertaking remedial actions.
During the remedial design phase, additional sampling will be required
to refine the area requiring remediation. If as a result of.this additional
sampling it is determined that total levels of contamination exceed the
minimum levels established to define dangerous waste, then additional
remedial alternatives that are applicable to the disposal of dangerous waste
will have to be considered for those sediments that qualify as dangerous
waste.
The confined aquatic disposal alternative was not selected because the
volume of material is compatible with the available nearshore disposal site.
The nearshore alternative can be implemented more quickly, while providing
a degree of protection that is appropriate for the contaminants of concern.
Solvent extraction/upland disposal and incineration/upland disposal
were not selected as preferred alternatives since the timeframe for remedial
action would be lengthened. Implementation would require bench-scale and
possibly pilot-scale testing and pilot burns. In addition, treatment itself
would take a considerable period of time, given available equipment and the
large volume of contaminated sediment. Removal (extraction) or destruction
(incineration) of contaminants due to the treatment processes is expected to
increase long-term protectiveness compared with nearshore disposal. However,
performance monitoring associated with the nearshore disposal facility would
allow early detection of movement to the surrounding environment. The
approximately $41 and $99 million greater cost for the extraction and
incineration options, respectively, also favor the nearshore disposal
5-51
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alternative for the large volume of contaminated sediments at moderate
levels of contamination.
Hydraulic dredging with upland disposal was not selected because of
uncertain disposal site availability and the high cost of siting and
developing a facility to appropriate technical standards for disposal of
untreated contaminated dredged material in an upland environment. This
alternative is feasible from both a technical and institutional standpoint.
The risk of system failures for disposal in the upland environment (e.g.,
groundwater risks) along with the high costs and disposal siting uncertain-
ties compromises its desirability.
No-action and institutional controls alternatives are ranked high for
technical feasibility, availability, and capital expenditures. However, the
failure to mitigate environmental and potential public health impacts far
outweighs these advantages.
5.7 CONCLUSIONS
The head of Hylebos Waterway was identified as a problem area because
of the elevated concentrations of both inorganic and organic contaminants in
the sediment. PCBs, arsenic, and HPAH were selected as indicator chemicals
to assess source control requirements, evaluate sediment recovery, and
estimate the area and volume to be remediated. In this problem area,
sediments with concentrations currently exceeding long-term cleanup goals
cover an area of approximately 381,000 yds and a volume of 381,000 yd3.
Some of the sediment is predicted to recover within 10 yr following imple-
mentation of all known, available, and reasonable source control measures,
thereby reducing the contaminated sediment volume by 164,000 yd-*. The
total volume of sediment requiring remediation is, therefore, reduced to
217,000 yd3-
The primary identified and potential sources of problem chemicals to the
head of Hylebos Waterway include the following:
• Process effluents from Pennwalt Chemical
• Drainage ditches including Kaiser Ditch, East Channel Ditch,
and Morningside Ditch
• Surface water runoff from Pennwalt Chemical (potential), log
sorting yards, General Metals, Kaiser Aluminum, and Tacoma
Boatbuilding Company
• Groundwater seeps and infiltration from Pennwalt Chemical,
log sorting yards, General Metals (potential), B&L Landfill,
and Kaiser (potential).
Source control measures required to correct these problems and ensure
the long-term success of sediment cleanup in the problem area include the
following actions:
5-52
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• Reduce the amount of metals in process effluent from Pennwalt
Chemical
• Reduce contaminant concentrations of metals, hydrocarbons,
and PCBs in the discharge from the ditches
• Reduce contamination in surface water discharging to the
waterway
• Reduce groundwater contamination discharges to the waterway
• Implement best management practices at the Tacoma Boatbuilding
Company facility
• Confirm that all sources of problem chemicals have been
identified and controlled
• Monitor sediments regularly to confirm sediment recovery
predictions and assess the adequacy of source control
measures.
It should be possible to control sources sufficiently to maintain
acceptable long-term sediment quality. This determination was made by
comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. The level of source control required for PCBs was estimated to
be approximately 89 percent compared to a technically feasible level of
approximately 70 percent. Additional evaluations to further delineate PCB
sources and refine these estimates will be required as part of the source
control measures described above. Source control requirements were developed
through application of the sediment recovery model for the indicator
chemicals PCBs, arsenic, and HPAH. The assumptions used in determining
source control requirements were environmentally protective. It is an-
ticipated that more detailed loading data will demonstrate that sources can
be controlled to the extent necessary to maintain acceptable sediment
quality. If the potentially responsible parties demonstrate that implemen-
tation of all known, available, and reasonable control technologies will not
provide sufficient reduction in contaminant loadings, then area requiring
sediment remediation may be re-evaluated.
For sediment areas not predicted to recover within 10 yr of implementa-
tion of source controls, clamshell dredging/nearshore disposal was recom-
mended as the preferred alternative. The selection was made following a
detailed evaluation of viable alternatives encompassing a wide range of
general response actions. Because sediment remediation will be implemented
according to a performance-based ROD, the alternative eventually implemented
may differ from the currently preferred alternative. The preferred
alternative meets the objective of providing protection for both human
health and the environment by effectively isolating contaminated sediments
in an engineered disposal facility where performance monitoring can be
readily implemented. Disposal sites for nearshore confinement are available
at this time. Use of material from the head of Hylebos Waterway in a
5-53
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nearshore disposal facility is compatible with the Port of Tacoma's
industrial development plans, minimizing the impacts of using another
facility. Concerns regarding potential contaminant migration to an adjacent
fish mitigation area will be addressed through the ongoing monitoring
program to detect potential problems in sufficient time to implement
corrective measures, if necessary. Nearshore disposal has been demonstrated
to be effective in isolating contaminated sediments (U.S. Army Corps of
Engineers 1988). The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 404 and 401 of the Clean Water Act, and other
applicable environmental requirements.
As indicated in Table 5-5, clamshell dredging/nearshore disposal
provides a cost-effective means of sediment mitigation. The estimated
capital cost to implement this alternative is $5,338,000. The present worth
of 30 yr of environmental monitoring and other O&M at the disposal site is
estimated to be $421,000. These costs include long-term monitoring of
sediment recovery areas to verify that source control and natural sediment
recovery have corrected the contamination problems in the recovery areas.
The total estimated present worth of the preferred alternative is $5,759,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control
• Limited information on disposal site availability and
associated costs.
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
5-54
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?ost-7ffecativ°eS' Utllize the most Protective solutions practicable, and
are
5-55
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6.0 MOUTH OF HYLEBOS WATERWAY
Potential remedial actions are defined and evaluated in this section
for the mouth of Hylebos Waterway problem area. The waterway is described in
Section 6.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 6.2 provides an overview of contaminant
sources, including site background, identification of apparent contaminant
sources, remedial activities, and current site status. The effects of
source control measures on sediment contamination levels are discussed in
Section 6.3. Areas and volumes of sediment requiring remediation are
provided in Section 6.4. The detailed evaluation of the sediment remedial
alternatives chosen for the problem area and indicator problem chemicals is
provided in Section 6.5. The preferred alternative is identified in
Section 6.6. The rationale for its selection is presented, and the relative
merits and deficiencies of the remaining alternatives are discussed. The
discussion in Section 6.7 summarizes the findings of the selection process
and integrates the required source control with the selected remedial
alternative.
6.1 WATERWAY DESCRIPTION
Hylebos Waterway is designated as a navigational waterway with a
required maintenance depth of 30 ft below MLLW. An illustration of the
waterway and the locations of nearby industries and businesses is presented
in Figure 6-1. The problem area designated as the mouth of Hylebos Waterway
extends from the mouth of the waterway to approximately 7,200 ft from the
mouth. Ttie width of the main channel measures between 600 and 1,000 ft in
this problem area, with a large intertidal area west of East llth Street
extending another 800 ft to the north. Recent subbottom profiling of
Hylebos Waterway in this area showed that mid-channel depths average between
approximately 37 and 44 ft below MLLW, with depths across the channel bottom
varying between 28 ft below MLLW at the south bank to 36 ft below MLLW at
mid-channel (Raven Systems and Research 1984). Total sediment accumulation
was estimated to be between 1 and 4 ft, with a pronounced 4-ft accumulation
along the south side of the waterway, adjacent to Occidental Chemical
Corporation. Sediments within Hylebos Waterway are typically silty sand
with an average composition of 64 percent fine-grained material (range of
44-78 percent) and 20 percent clay (Tetra Tech 1985b). Sedimentation rates
diminish from the mouth to the head (Tetra Tech 1987b).
Hylebos Waterway was formed by dredging the Puyallup River delta in the
early 1920s. Since that time, the southern shoreline of the waterway has
become heavily industrialized. Industrial development along the north
6-1
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I SOUND RFFMNG.NC
2 CASCADE TWBERYARDJ1
3 BUFFEIENWOOOWOHKWGCO
4 HYDHO SYSIEMS ENGMEERMG
UODUIECH MARINE. NC,
5 KNAPPBOATBUILDHG
B HARBOR SERVICE
HVLEBOS UARMA
HYLEBOS BOAT HAVEN
7 JONESCHCMCAL
> GENERAL METALS. NC
i TACOMA8OAIBUI.OMG
10 MANKE LUMBER
I 11 MARWE.METAL MFG.
12 JONESGOOOELLCORP
13 MAIIIJI METALS
MAIiME SUPPLY
14 SIHllCHBROTKEFtS. NC.
15 REPUBLIC SUPPLYCO
PEDERSONO1
16 WASSER WINTERS
17 LOUISIANA PACIf 1C
18 GLACIER SAND I GRAVEL
l» KAISER ALUMHUMl CHEMICAL
20 BONNEVltE POWER ADUH
21 CITY OF TACOMA SUBSTATION
22 PORTAC.NC
23 WEYERHAEUSER
24 DUNLAPTOWNG
29 CASCADE TMBER YARD K
26 PETROLEUM RECIAMNG SERVICE. MC
27 PENNWALT CHEMICAL CORP
28 PENNWALT AGCHEM DIV
2« FH1DSPROOUCIS.INC
BIINE TRANSPORT
30 KtlCHHOIUCIIEMCAL
31 Rf.CHHOLDCHEMCAL
32 PUGE F CHEMCAL CO.
33 WESTERN TURNMG
34 SUPERLONPIPE
35 AOLEKPHESS
36 ACCURATE PACKAGING. WC
HAUSERMAN E DUCAIORS DIV
TACOMABOAICO
37 PACriC PAPER PHODUCIG
3» SIANDAROMECHANCAL.tlC
3B UNICO ENGNE ERMG
40 CHEMICAL PROCESSORS
41 BRAZIER LUMBER
42 Cl TY OF IACOMA FIRE STATION
43 P O CORP
44 MISC COMMERCIAL BUSINESSES
49 US GYPSUM
4ft MURRAY PACIFIC YARD tl
47 BUFFELENWOODWORKMGCO
48 CENEX FEED PLANT
« NORD1UNDBOATCO. NC
50 HAL STEEL LOCOMOTIVES
51 BHAZKR LUMBER
52 CITYOFTACOMA
S3 NAVAI RISLHVLMAINriFWINING (ACUITY
54 NAVAlANDMAIWECORI>SKLSERVECtNltl<
M 1ACOMABOAIBUIDNGCO
56 PR) NORTHWEST. NC
V TOIEMOCEANInAIIRfXPfffSSIIOIII
SB OCCIOlNIALCHEUCAl COUP
W PORT OF TACOMA NDUSIHIA1 YAI»
60 MCCMABOATBUHDMGCO
61 COMMTrNCCMENT BAYCORFtlOMED
ro
l«s Property boundaries are approximate
baaed on aerial pbcloo>aphs and drive
by inspections
Figure 6-1.
Mouth of Hylebos Waterway - Existing industries
and businesses.
-------
shore has not been as extensive as that along the south shore, due princi-
pally to the limited land area available between the waterway and the steep
bluffs.
Dredging by the Port of Tacoma and the U.S. Army Corps of Engineers has
changed the shape and size of Hylebos Waterway. When created in the 1920s,
the waterway extended only to the point of what is now the lower turning
basin. In the mid-1950s, the Port of Tacoma extended the waterway approxi-
mately 3,800 ft (Tetra Tech 1986c). Subsequent dredging by the U.S. Army
Corps of Engineers widened the upper reaches of the waterway and created the
upper turning basin at the head of the waterway (Dames & Moore 1982).
6.1.1 Nature and Extent of Contamination
An examination of sediment contamination data obtained during both the
RI/FS sampling efforts (Tetra Tech 1985a, 1985b, 1986c) and historical
surveys has revealed that the mouth of Hylebos Waterway contains elevated
concentrations of organic materials. PCBs were identified as a Priority 1
contaminant in the waterway. Priority 2 contaminants that have been
identified in the mouth of Hylebos Waterway include hexachlorobenzene,
trichloroethene, tetrachloroethene, 1,2-dichlorobenzene, 1,3-dichlorobenzene,
hexachlorobutadiene, a pentachlorocyclopentane isomer, and lead. The
following organic and inorganic compounds exceeded their corresponding AET
values at only one station sampled, and are therefore considered Priority 3
contaminants: HPAH, LPAH, methylphenanthrene, methylpyrene, biphenyl,
phenol, benzyl alcohol, copper, and zinc.
The area of concern in the mouth of Hylebos Waterway has been defined
as the entire deep water portion of the problem area (Tetra Tech 1985b).
Although cross-channel sampling was limited, existing data showed sediments
from the southern side of the waterway to be more contaminated than those
from the middle or north side. Selected chlorinated compounds from sediments
along the south shore were present in the highest concentrations observed
throughout Commencement Bay.
PCBs and hexachlorobenzene were selected as indicator chemicals for the
mouth of Hylebos Waterway. Surface sediment enrichment ratios (i.e., ratio
of observed concentration to long-term cleanup goal) for these two con-
taminants were higher over a greater area than for other identified problem
chemicals. These contaminants were also selected because they represent
surface runoff and contaminant loading to the waterway from Occidental
Chemical Corporation (see Section 6.2.1).
The highest concentrations of PCBs in the mouth of Hylebos Waterway
were restricted to the southern shore of the waterway. PCB concentrations
dropped abruptly with increasing distance from the south shoreline (Tetra
Tech 1985a), suggesting that the source of PCB contamination is or was along
the southern shore of the waterway.
Concentrations of chlorinated benzene compounds were highest approxi-
mately 4,000 ft from the mouth of the waterway. Decreasing concentrations
with distance from this area suggest the presence of a source in that
6-3
-------
immediate vicinity (Tetra Tech 1985a). There was no apparent cross-waterway
contamination gradient in the problem area. Review of data collected during
the RI for the spatial distributions of chlorinated hydrocarbons led to the
conclusion that the chlorinated benzenes and chlorinated butadienes were
derived from a common source.
Areal and depth distributions of PCBs and hexachlorobenzene in the mouth
of Hylebos Waterway are shown in Figures 6-2 and 6-3, respectively.
Concentrations are normalized to cleanup goals, which are 150 ug/kg for PCBs
and 22 ug/kg for hexachlorobenzene. Values above 1.0 define problem
sediments. The cleanup goal for PCBs was set by data for bioaccumulation of
the contaminant in English sole muscle tissue. The cleanup goal for
hexachlorobenzene was set by the benthic infauna AET.
Included in Figures 6-2 and 6-3 are contaminant depth profiles for
core samples collected as part of the FS. Although surface minima were
noted for PCBs in the problem area, recent investigations (Stinson et al.
1987) suggest that there are ongoing sources of this contaminant. Of the
four core samples collected during the RI, three showed an increase of
chlorinated hydrocarbons with depth. Subsurface infiltration of contaminated
groundwater at permeable horizons has been suggested for the increases
(Tetra Tech 1985a). Remediation to a depth of 2 yd was assumed based on
available core data.
6.1.2 Recent and Planned Dredging Pro.iects
The most recent dredging in the mouth of Hylebos Waterway was confined
to three small areas in the vicinity of the llth Street Bridge. Since 1972,
the only dredging in the waterway has been performed by specific industries
along the waterfront (Tetra Tech 1985a).
The Puyallup Indians have applied for a permit to excavate an upland
area adjacent to a highly productive and heavily used intertidal fish
rearing habitat at the mouth of Hylebos Waterway. The excavated material
will be relocated to an existing spit to the west, thereby increasing the
intertidal area behind the spit. The new spit elevation will be 14 ft above
MLLW, and the existing intertidal area will increase by 35-40 percent. A
total of 10,800 yd3 of sediment will be placed in the new spit (U.S. Army
Corps of Engineers, 10 November 1988, personal communication). Businesses
and industries that responded when queried about future dredging plans are
itemized below:
• Occidental Chemical Corporation does not plan to dredge at the
mouth of Hylebos site in the near future, but will probably
apply for a dredging permit within 3-5 yr (Hartman, R.,
22 October 1987, personal communication).
6-4
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MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984(1979-1981)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
PCBs UNDETECTED
•o
>.
? 1.0H
Q.
LU
Q
1.5-
2.0-^
PCS
0 400 800 1200 1600 2000
01 5 10
RATIO TO CLEANUP GOAL
0-1
0.5-
\ a
\
Open symbols designate
d0t0cbon limits of
undet«ct«d samples.
HY-96
Figure 6-2. Areal and depth distributions of PCBs in sediments
at the mouth of Hylebos Waterway, normalized to
long-term cleanup goal.
6-5
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MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
HEXACHLOROBENZENE (|ig/kg)
0 200 400 600 MO 1.000 1.200
1 ' '| ' 'I ' ' I1 ' t ' I '
0 10 20 30 40 SO
RATIO TO CLEANUP GOAL
0.5-
1.0-
ul
o
1.5-
2.0 J
HY-90
Figure 6-3. Areal and depth distributions of hexachlorobenzene in
sediments at the mouth of Hylebos Waterway, normalized
to long-term cleanup goal.
b-o
-------
• Tacoma Boatbuilding Company does not foresee any need to
dredge because silt buildup (which is periodically checked)
is slow in their channel. The company last dredged approxi-
mately 10 yr ago. The company plans to build a dock at its
leased Port of Tacoma site. Although this construction will
require dredging, a permit has not yet been requested
(Brady, B., 22 October 1987, personal communication).
• Totem Ocean Trailer Express, and the Naval and Marine Corps
Reserve Center do not plan any dredging projects in the
foreseeable future (Bimick, B., 22 October 1987, personal
communication; Kuzek, Lt., 22 October 1987, personal
communication).
The U.S. Army Corps of Engineers has not received any recent requests for
dredging permits. However, the Port of Tacoma and the U.S. Army Corps of
Engineers have suggested that navigational channels in the Commencement Bay
area may be deepened in the future to accommodate large vessels with deeper
drafts.
6.2 POTENTIAL SOURCES OF CONTAMINATION
This section provides an overview of the sources of contamination to
the sediments in the mouth of Hylebos Waterway and a summary of available
loading information for the contaminants of concern. Because the north
shore of Hylebos Waterway is primarily steep bluffs, industrial development
has not been as extensive as that along the south shore (see Figure 6-1).
In this area of the waterway, there are no industries along the north shore.
Much of the intertidal area is used for log storage and marina facilities
(Tetra Tech 1986c).
Occidental Chemical Corporation (formerly Hooker Chemical and Plastics
Corporation) was among the first industries established along Hylebos
Waterway. The facility began operations in the 1920s to provide chlorine
for pulp and paper industries. Occidental also operated an organic solvents
plant between 1947 and 1973. Occidental Chemical is one of the five NPDES-
permitted facilities located along Hylebos Waterway (Figure 6-4), and the
only permitted discharge to this problem area. The facility's main outfall
(HY-707) is classified as a major industrial discharge under the NPDES
program (Permit #WA0037265). Nonperntitted discharges associated with
Occidental include seven steel pipes (HY-085), two groundwater seeps
(HY-083), and the groundwater beneath the facility. There are numerous other
nonpermitted surface water discharges to the problem area (Figure 6-4).
Other industrial facilities located along the banks of the mouth of Hylebos
Waterway include Tacoma Boatbuilding Company, PRI Northwest, Inc., and the
Port of Tacoma industrial yard.
Table 6-1 provides a summary of problem chemicals and source status
information for the area. The high concentrations of chlorinated hydro-
carbons in the sediments of the mouth of Hylebos Waterway have been
attributed to the Occidental Chemical Corporation, based on their proximity
to the problem area, known use of problem chemicals, and presence of soil
6-7
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CT1
I
00
Reference: TetraTech(1985b).
meters
1000
Figure 6-4. NPDES-permitted and nonpermitted dischargeslo Hylebos Waterway.
-------
TABLE 6-1. MOUTH OF HYLEBOS WATERWAY - SOURCE STATUS3
Chemical /Group
peris
Irichloroethene
letrachloropthene
llexachloroben/ene
1 ,2 Dichlorobenzene
1,3 Dichlorobenzene
llexachlorohutadiene
Pent achlorocyclopentane
i somnr
III' AH
LPAH
Mnlhyl phpnanl hrene
Methyl pyrene
Riphenyl
load
Copper
/inc
Phriiol
Hpn/yl .ilcohol
Chemical
Priority''
1
2
2
2
2
2
2
2
3 (MY 02)
3 (IIY-02)
3 (IIY 36)
3 (HY-36)
3 (HY-36)
2
3
3
3 (HY-36)
3 (IIY-41)
Sources
Occidental Seep H\
Locomotive yards
Occidental surface
water runoff
Occidental ground-
water infiltration
Ubiquitous oi 1 spi 1 Is
Occidental
Storm drains
Historical
Unknown
Source ID
Yes
Yes
Yes
Yes
Potential
Yes
Yes
No
No
Source Loading
Insufficient data
Nn
Source loading
calculations for
Cl ethenes,
Cl-benzenes,
Cl-butadienes
No
No
Yes
Yes
No
No
Source Status
UnknoMn
Ongoing
Solvent plant operations
terminated in 1973;
surface runoff and ground
water are ongoing sources
Direct discharge of chlor-
inated hydrocarbons
associated with chlorine
prediction has decreased
Sporadic, ongoing
Ongoing
Ongoing
NA
NA
Sediment Profile Trends
Variable; data limitations
Surface and subsurface
maxima
Variable
Variable; lead has surface
minimum
c
c
en
I
UD
8 Source information and sediment information blocks apply to all chemicals in the
respective group, not to individual chemicals only.
1* Tor Priority 3 chemicals, the station exceeding AE1 is noted in parentheses.
c Not evaluated for this study.
-------
and groundwater contamination at the facility (Tetra Tech 1985b). This
facility has also been identified as a potential source of PCBs based on
sediment samples collected adjacent to one of the groundwater seeps below the
former Occidental solvents plant (Stinson et al. 1987). Although the
locomotive yards have been identified as a potential source of PCBs to
Hylebos Waterway, this facility is located well outside of the problem area.
In addition, the sample exhibiting significant PCB concentrations was
collected from a waste oil channel with no apparent route by which the
material could enter Hylebos Waterway (Stinson et al. 1987).
6.2.1 Occidental Chemical Corporation
The Occidental Chemical Corporation chemical production facility is
situated on Hylebos Waterway between East llth Street and Commencement Bay.
The 33-ac site is bordered by Alexander Avenue on the southwest and by
Hylebos Waterway on the northwest. The facility operated as the Hooker
Chemicals and Plastics Corporation from the initiation of operations in 1929
until the 1980s, when the name of the operation was changed to the current
title.
Chlorine and sodium hydroxide have been manufactured by electrolysis
ever since the plant opened. Production continues today. The facility also
contains an ammonia plant and a muriatic acid plant. Industrial solvents
were manufactured at the site from 1947 to 1973. In 1973, the solvent
production equipment was dismantled and removed from the property (Walker
Wells 1980a). Wastes generated during the active period of solvent
production (1947-1973) were reportedly either discharged to Hylebos Waterway,
disposed of at a deep-water disposal site within Commencement Bay, or buried
onsite in unlined lagoons or pits (Boys, P. and J. Sceva, 3 July 1979,
personal communication). From approximately mid-1972 until the solvents
plant closed in 1973, solid wastes were removed for offsite disposal at
several upland sites in the Commencement Bay vicinity. From 1929 to 1969 or
1970, effluents from the chlorine production operations were discharged
directly to Hylebos Waterway through the main plant effluent (Boys, P. and
J. Sceva, 3 July 1979, personal communication). Since that time, chlorinated
organic compounds generated by the chlorine purification unit have been
disposed of by offsite incineration. The effluent from the chlorine
stripper continues to be discharged to Hylebos Waterway along with the total
plant effluent.
As indicated previously, Occidental Chemical Corporation has also been
identified as a potential source of PCB contamination to the waterway, based
on sediment data in the vicinity of the groundwater seeps adjacent to the
facility. However, soil testing conducted on the site has not produced any
significant positive results (Robb, S., 9 May 1988, personal communication).
In addition, groundwater beneath the site did not exhibit PCB contamination.
A sample from an offsite well adjacent to the Occidental facility had a low,
but measurable PCB concentration (Massimino, C., 13 May 1988, personal
communication). The company does have electrical transformers on the site.
Occidental Chemical was identified as a source of problem chemicals
found in the sediments of Hylebos Waterway based on its proximity to the
6-10
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problem area, its documented use of problem chemicals, and measurements of
pollutant concentrations in groundwater and effluent. Occidental Chemical
is the only confirmed source of chlorinated hydrocarbons (chlorinated
ethenes, butadienes, and benzenes) and mercury to the mouth of Hylebos
Waterway.
Identification of Contaminant Sources Onsite--
Current discharges associated with Occidental Chemical Corporation
include the main plant outfall (HY-707), surface drain (HY-085), groundwater
seeps (HY-083), and the groundwater beneath the plant site. Of these four
confirmed sources of contaminants to Hylebos Waterway, it has been estimated
that groundwater currently contributes the majority of the loadings,
followed by the main plant outfall (Appendix E, Table E-10). In addition,
subsurface soils in the vicinity of past onsite disposal areas contain
significant quantities of chlorinated organic compounds, largely beneath
areas of the site that have been excavated and then paved.
Groundwater contamination at the site has resulted primarily from the
past onsite disposal of solvent plant wastes containing 3,000-4,000 mg/L of
chlorinated organic compounds (Tetra Tech 1986c). These compounds included,
but were not limited to, methylene chloride, chloroform, trichloroethylene,
perch!oroethylene, tetrachloroethane, hexachlorobutadiene, and various
chlorinated ethenes. Chlorinated organic concentrations approaching
700 mg/L have been detected in groundwater at the site. The groundwater
plume at the Occidental Chemical site is currently estimated to cover the
western half of the site, with the major zone of contamination in the 25- to
50-ft depth zone. However, contamination was observed to a depth of 115 ft
in the vicinity of the former solvents plant. Walker Wells (1980a) estimated
that 19,000-35,000 Ib of chlorinated organic contaminants were contained in
the saturated zone beneath the facility. Total chlorinated organics loading
to the waterway as a result of groundwater discharge has been estimated to
range from approximately 5.5 to 12 Ib/day (Walker Wells 1980a). Recent
monitoring data indicates that the chlorinated organic content of groundwater
beneath the facility has not declined appreciably since the monitoring
effort began (Stoner, M., 26 April 1988, personal communication).
Chlorinated organic contaminants have also been identified in the
unsaturated zone beneath the Occidental Chemical site. In 1980, 10,725 Ib of
chlorinated organics were estimated to be present in this zone (Walker Wells
1980a). Although subsurface soil containing greater than 150 mg/kg chlori-
nated organic contaminants has since been removed, residual contaminants in
the unsaturated zone could percolate to the surficial aquifer beneath the
site and eventually migrate to Hylebos Waterway (Ecology 1986).
Surface water runoff represents an additional potential source of
contamination to the adjacent waterway. The documented releases of con-
taminated surface water from the Occidental Chemical Corporation (HY-085,
see Appendix E) have been associated with relatively small flows
(700 gal/day). However, there is potential for shallow contaminated
groundwater to infiltrate storm sewer lines and subsequently enter Hylebos
Waterway. Because the most highly contaminated soil has been removed and
6-11
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most of the site paved, surface water runoff does not appear to be a
significant contaminant transport mechanism to Hylebos Waterway (Robb, S.,
7 October 1987, personal communication). However, additional investigation
is necessary to confirm this conclusion.
Recent and Planned Remedial Activities--
A number of remedial measures have already been undertaken by Occidental
Chemical and a number of others are planned. These measures included soil
excavation, groundwater remediation, process controls, and runoff controls.
These measures are being undertaken pursuant to the stipulations of the RCRA
Part B permit application and the Continuing Releases portion of the
application for the site (Stoner, M., 26 April 1988, personal communication).
It is anticipated that the approved RCRA Part B permit will be issued in the
fall of 1988 (PTI 1988a).
As indicated previously, contamination of Hylebos Waterway via ground-
water occurs largely from onsite disposal of solvent plant wastes in unlined
lagoons and pits. In response to an Ecology order, Occidental Chemical
Corporation removed 1,585 yd^ of soil exceeding 150 mg/kg chlorinated
organics and paved remaining subsurface areas containing at least 15 mg/kg
(Ecology 1986). Approximately 87 percent (9,368 Ib) of the estimated
10,725-lb reservoir of chlorinated hydrocarbons was removed by this action.
Based on data submitted to U.S. EPA by Occidental Chemical (Stoner, M.,
26 April 1988, personal communication), significant improvement in ground-
water quality has not been observed since contaminated soils were removed.
Runoff from the paved areas has been routed to the facility's main outfall.
Occidental Chemical Corporation has recently proposed a groundwater
pumping, collection, and treatment program. Proposed treatment technologies
include air stripping, carbon adsorption, steam stripping, and air stripping
backed by carbon (Hartman, R., 1 May 1987, personal communication). Initial
groundwater analyses have indicated that air stripping is not a viable
option because of air quality emission limitations. Steam stripping has
been tentatively identified by Occidental Chemical as the technology of
choice (Hartman, R., 1 May 1987, personal communication). Additional design
data are required for final selection of the groundwater treatment tech-
nology -
In-plant modifications have also been undertaken to minimize the
discharge of chlorinated organics to Hylebos Waterway through the main plant
outfall. The chlorine steam stripper is the only in-plant wastestream
discharged through the main outfall that contacts toxic chlorinated com-
pounds. A taller chlorine stripping tower has been installed and steam
temperatures are now regulated at the top of the tower instead of the
bottom. Chlorinated hydrocarbon concentrations in the stripper effluent
have been reduced by approximately 95 percent (0.2 vs. 5.2 Ib/day). These
changes represent the best control available for graphite anode diaphragm
cell technology, and hence the lowest achievable level of residual chlor-
inated hydrocarbon content (Scholes, D., 9 October 1985, personal communi-
cation). Other upgrades to in-plant operations and waste handling practices
have also significantly reduced direct discharges to the waterway.
6-12
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Occidental Chemical Corporation has been developing plans to dredge
Hylebos Waterway in the vicinity of their dock. Sampling plans for the
dredging were reviewed and approved by Ecology on 5 December 1984, and
sediments were sampled by a contractor to Occidental Chemical on 10 December
1984 under Ecology supervision. Additional sampling is planned. However,
as of this writing, no additional sampling or dredging has been accomplished
(Hartman, R., 8 July 1988, personal communication). Previous sediment
samples analyzed in 1983 showed high concentrations of chlorinated organic
compounds.
6.2.2 Loading Summary
Where possible, source contaminant loading calculations have been
updated to include data collected since the completion of the Remedial
Investigation (Tetra Tech 1985a, 1986c). Summary loading tables for the
Priority 1 and 2 contaminants of concern for the mouth of Hylebos Waterway
(i.e., lead, PCBs, chlorinated ethenes, chlorinated benzenes, chlorinated
butadienes, and pentachlorocyclopentane isomer) are provided in Appendix E.
The only discharge to the mouth of Hylebos Waterway for which post-RI
loading data are available is Occidental Chemical's main outfall HY-707
(Hartman R., 30 June 1987, personal communication).
Data from Occidental Chemical's main outfall (HY-707) have been
collected primarily for two sampling periods, one in 1979 and the second in
1986. Data for seven inorganic compounds and the chlorinated hydrocarbons
reveal a significant decrease in loadings to the waterway over that period.
Loading rates dropped between 40 percent (zinc) and 99 percent (arsenic and
nickel). From the limited data available for the chlorinated organic
compounds, similar loading reductions have been realized (80 percent for
chlorinated butadienes and 95 percent for chlorinated benzene). Available
flow data indicate that the main outfall accounts for greater than 95 percent
of the measured inputs to the problem area.
The seven steel pipes that constitute HY-085 were found to discharge
less than 0.003 Ib/day of the six inorganic and three organic variables
measured at various times between 1980 and 1984 (one or two sampling events
for each variable measured). The two groundwater seeps present in the
vicinity of Occidental Chemical (HY-083) also revealed detectable levels of
four inorganic compounds and chlorinated ethenes during sampling in 1984.
Loading rates ranged from less than 0.0002 Ib/day for the chlorinated
ethenes to 0.012 Ib/day for zinc.
6.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the effects of source control and natural
recovery processes were evaluated. This evaluation was based on contaminant
6-13
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concentrations in the sediments, and assumptions regarding the relationship
between sources and sediment contamination. Included within the evaluation
was an estimate of the degree of source control needed to maintain acceptable
sediment quality over the long term.
6.3.1 Feasibility of Source Control
In this section, known sources of contamination are summarized,
available control technologies are identified, and contaminant reductions
technically achievable through the use of all known, available, and
reasonable technologies are estimated. The identified source of several
problem chemicals in the mouth of Hylebos Waterway (e.g., chlorinated
ethenes, chlorinated butadienes, chlorinated benzenes, and metals) is the
Occidental Chemical site.
The Occidental Chemical facility has been associated with elevated
concentrations of problem chemicals in adjacent sediments. Process
effluents, runoff, and groundwater seepage are suspected as three of the
primary ongoing or historical sources of contaminants to the waterway.
Some remedial actions and best management practices have already been
implemented at the facility: soil highly contaminated with chlorinated
organic compounds has been excavated and disposed of offsite, soil in areas
with lower concentrations of chlorinated organic compounds has been paved
to minimize infiltration and leaching, and process modifications have
substantially reduced contaminant discharges via the main plant effluent.
Groundwater beneath the facility remains as the major potential contaminant
source to the waterway. Additional groundwater quality and hydrogeological
data being collected under the RCRA Continuing Releases Program will aid in
defining the preferred technologies for the collection and treatment of
contaminated groundwater.
Available technologies for mitigating groundwater contamination include
various means of collecting and treating contaminants, gradient controls to
contain or divert groundwater flow, and in situ biological treatment
methods. As indicated previously, Occidental Chemical has proposed a pump
and treat program that may include steam stripping as the method of choice
for removal of chlorinated organic contaminants.
Available technologies for controlling surface water runoff include
removal of contaminant sources within the drainage basin, methods for
retaining runoff onsite (e.g., berms, channels, grading sumps), and revegeta-
tion or paving to reduce erosion of waste materials (see Section 3.2.2).
Identification of control technologies for further reducing effluent
concentrations of problem chemicals through operation or in-plant modifica-
tion are beyond the scope of this document.
Based on the nature of the contaminants, the source pathways that have
been identified, and available control technologies, it is estimated that
implementation of all known, available, and reasonable (i.e., feasible)
technologies will reduce source inputs of chlorinated hydrocarbon con-
taminants by approximately 95 percent. The sources and pathways of PCB
6-14
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contamination to the waterway are less clearly defined. Although Ecology
has determined that sediments adjacent to the groundwater seeps were
contaminated with PCBs (Stinson et al. 1987), they have not been detected in
groundwater beneath the facility (Stoner, M.( 28 April 1988, personal
communication). They have been detected, however, at concentrations less
than 2 ug/L in a well on adjacent Port of Tacoma property. For the purposes
of evaluating the effects of source controls, it is estimated that implemen-
tation of all known, available, and reasonable technologies will reduce
source inputs of PCBs by approximately 60 percent. This estimate is based on
the lack of available information regarding specific PCB contaminant sources
and pathways of migration.
Conclusion--
For the mouth of Hylebos Waterway problem area, the estimated maximum
feasible level of source control for the two indicator chemicals is assumed
to be 95 percent for hexachlorobenzene and 60 percent for PCBs. These
estimates reflect both the assumed effectiveness of planned remedial
measures (including best management practices) for the control of chlorinated
hydrocarbons as well as uncertainty regarding PCB sources and migration
pathways to the waterway. More precise source control estimates require
improved definition of the sources of PCBs, which is beyond the scope of this
document.
6.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals PCBs and hexachlorobenzene. Results are
reported in full in Tetra Tech (1987a). A summary of those results is
presented in this section.
The depositional environment at the mouth of Hylebos Waterway can be
reasonably well characterized by a sedimentation rate of 2,500 mg/cm^/yr
(1.77 cm/yr) and a mixing depth of 10 cm. Two indicator chemicals (hexa-
chlorobenzene and PCBs) were used to evaluate the effect of source control
and the degree of source control required for sediment recovery. Losses due
to biodegradation and diffusion were determined to be negligible for these
chemicals. Two timeframes for sediment recovery were considered: a
reasonable timeframe (defined as 10 yr) and the long term. Source loadings
of both indicator chemicals at the mouth of Hylebos Waterway were assumed to
be in steady-state with sediment accumulation. Results of the sediment
recovery evaluation are summarized in Table 6-2.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times are predicted to
be 11 yr for PCBs and 24 yr for hexachlorobenzene. These predictions are
based on the highest concentrations of the indicator chemicals measured in
the problem area. Therefore, sediment recovery in the 10-yr timeframe is not
6-15
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TABLE 6-2. MOUTH OF HYLEBOS WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
PCBs Hexachlorobenzene
Station with Highest Concentration
Station identification HY-42 HY-96
Concentration (ug/kg dry weight) 1,100 1,000
Enrichment ratio3 7.3 45.4
Recovery time if sources are
eliminated (yr) 11 24
Percent source control required
to achieve 10-yr recovery NP& NPb
Percent source control required
to achieve long-term recovery 86 98
Average of Three Highest Stations
Concentration (ug/kg dry weight) 1,050 590
Enrichment ratio3 7.0 26.8
Percent source control required
to achieve long-term recovery 86 96
10-Yr Recovery
Percent source control assumed
feasible 60 95
Highest concentration recovering
in 10 yr (ug/kg dry weight) 300 101
Highest enrichment ratio of sediment
recovering in 10 yr 2.0 4.6
3 Enrichment ratio is the ratio of observed concentration to cleanup goal
b NP = Not possible.
6-16
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predicted to be possible. Minimal reductions in sediment concentrations are
predicted unless sources are controlled.
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source controls
is expected to reduce source inputs by 60 percent for PCBs and and by
95 percent for hexachlorobenzene. With this level of source control as an
input value, the model predicts that sediments with an enrichment ratio of
2.0 for PCBs (i.e., PCB concentrations of 300 ug/kg dry weight) and 4.6 for
hexachlorobenzene (i.e., hexachlorobenzene concentrations of 101 ug/kg dry
weight) will recover to the long-term cleanup goal within 10 yr (Table 6-2).
The surface area of sediments not recovering to the long-term cleanup goal
within 10 yr is shown in Figure 6-5. For comparison, sediments currently
exceeding cleanup goals for indicator chemicals are also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that 86 percent of the PCBs and 96 percent of the
hexachlorobenzene inputs must be eliminated to maintain acceptable con-
taminant concentrations in freshly deposited sediments (Table 6-2). These
estimates are based on the average of the three highest enrichment ratios
measured for the indicator chemicals in the problem area.
These values are presented for comparative purposes; the actual percent
reduction required in source loading is subject to the uncertainty inherent
in the assumptions required to apply the predictive model. These ranges may
represent upper limit estimates of source control requirements since the
assumptions incorporated into the model are considered to be environmentally
protective.
6.3.3 Source Control Summary
The major identified source of hexachlorobenzene to the mouth of
Hylebos Waterway is the Occidental Chemical Corporation. The source of PCBs
to the mouth of Hylebos Waterway is currently undefined and is potentially
historic. If the sources of PCBs and hexachlorobenzene are completely
eliminated, then it is predicted that sediment concentrations in the surface
mixed layer of the indicator chemical PCBs will decline to the long-term
cleanup goal of 150 ug/kg in approximately 11 yr, while those of hexachloro-
benzene (with a long-term cleanup goal of 22 ug/kg) will require 24 yr.
Sediment remedial action will therefore be required to mitigate the observed
and potential adverse biological effects associated with sediment conta-
mination within a reasonable timeframe.
Substantial levels of source control will also be required to maintain
acceptable sediment concentrations of hexachlorobenzene and PCBs even with
sediment cleanup. The estimated percent reduction required for long-term
maintenance is 86 percent for PCBs and 96 percent for hexachlorobenzene,
based on the average of the three highest observed sediment concentrations
for both indicator chemicals.
6-17
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00
Mouth of Hylebos Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA (yd 2)
VOLUME (yd3)
IN 10 YR
DEPTH (yd)
AREA (yd 2)
VOLUME (yd3)
2
393,000
786,000
2
115,000
230,000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
PCBs(AET=150ng/kg)
HEXACHLOROBENZENE (AET
Figure 6-5. Sediments at the mouth of Hylebos Waterway not meeting cleanup goals for
indicator chemicals at present and 10 yr after implementing feasible source control.
-------
With 95 percent source control assumed to be feasible (i.e., known,
available, and reasonable) for hexachlorobenzene, it should be possible to
maintain acceptable sediment quality for chlorinated hydrocarbon inputs
following sediment remediation. Whether or not maintaining sediment
quality is possible will be a function of the accuracy of the estimated
percent reduction of hexachlorobenzene required for long-term maintenance.
Furthermore, any groundwater infiltration to the sediments that may be
occurring must be effectively controlled through the groundwater pumping and
treatment program. Because the sources of PCB in the problem area are
undefined, only 60 percent source control was assumed feasible. Data from
the RI (Tetra Tech 1985a) and this study suggest a historical source,
because surface minima were present in the core samples. The estimated
percent reduction required to maintain acceptable sediment quality for PCBs
has been estimated to be approximately 86 percent, well above the 60 percent
feasible level used to evaluate sediment recovery with the model. If
implementation of all known, available, and reasonable control technologies
fails to achieve the necessary level of source control required to maintain
sediment quality, then re-evaluation of the area requiring remediation based
on PCB contamination may be required. However, if further testing determines
that the sources of PCBs to this problem area are historic, then maintenance
of the cleanup goal (150 ug/kg) in sediments would be feasible.
6.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with PCB or hexachlorobenzene
concentrations exceeding long-term cleanup goals is approximately 786,000 yd3
(see Figure 6-5). This volume was estimated by multiplying the area! extent
of sediment exceeding the long-term cleanup goal (393,000 yd2) by the
estimated 2-yd depth of contamination (see contaminant sediment profiles in
Figures 6-2 and 6-3). The estimated thickness of contamination is only an
approximation because few sediment profiles were collected and the vertical
resolution of these profiles was poor at the depth of the contaminated
horizon. For the volume calculations, depths were slightly overestimated.
This conservative approach was taken to reflect the fact that depth to the
contaminated horizon cannot be accurately dredged, to account for dredge
technique tolerances, and to account for uncertainties in sediment quality
at locations between the sediment profile sampling stations. This approach
also accounts for the possibility that the depth of the contaminated horizon
may vary significantly throughout the problem area, either as a result of
past disposal practices or groundwater inputs to the sediments.
The total estimated volume of sediments with PCB or hexachlorobenzene
concentrations that are expected to exceed long-term cleanup goals 10 yr
following implementation of feasible levels of source control is 230,000 yd^.
This volume was estimated by multiplying the areal extent of sediment
contamination with enrichment ratio greater than 2.0 for PCBs and 4.6 for
hexachlorobenzene (see Table 6-2), an area of 115,000 yd2, by the estimated
2-yd depth of contamination. These volumes are also approximations,
accounting for uncertainties in sediment profile resolution and dredging
tolerances. The quantity of sediment used in evaluating the remedial
alternatives (i.e., to identify the preferred alternative) was 230,000 yd^.
6-19
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This volume of sediment will require remediation at the mouth of Hylebos
Waterway.
6.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
6.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion, this set of alternatives is
evaluated to determine the suitability of each alternative for the remedia-
tion of contaminated sediments in the mouth of Hylebos Waterway. Remedial
measures address contaminated sediments that are predicted to exceed cleanup
goals 10 yr after implementing feasible source controls and allowing natural
recovery processes to occur. Remedial efforts in this problem area are
complicated by the uncertainties regarding the extent of contamination with
depth for the chlorinated organic compounds. In the event that the depth of
contamination is determined to be excessive (e.g., greater than 2 times
current estimates), criteria regarding disposal site availability and
appropriate dredging technologies may warrant re-evaluation. The objective
of this evaluation is to identify the alternative considered preferable to
all others based on CERCLA/SARA criteria of effectiveness, implementability,
and cost, using available data.
The first step in this process is to assess the applicability of each
alternative to remediation of contaminated sediments in the mouth of Hylebos
Waterway. Site-specific characteristics that must be considered in such an
assessment include the nature and extent of contamination; the environmental
settings; and site physical properties such as waterway usage, bathymetry,
and water flow conditions. Alternatives that are determined to be
appropriate for the waterway can then be evaluated based on the criteria
discussed in Chapter 4.
To aid in evaluating contamination in the mouth of Hylebos Waterway, the
organic indicator chemicals PCB and hexachlorobenzene were selected to
represent sediment contamination in this problem area. Occidental Chemical
has been identified as the primary source of hexachlorobenzene contamination
to the waterway (see Table 6-1). The source of PCB contamination is
currently undefined and may be historic. Areal distributions for both
indicators are presented in Figure 6-5 to indicate the degree to which
contaminant groups overlap based on long-term cleanup goals and estimated
10-yr sediment recovery.
The extensive PCB and hexachlorobenzene contamination in the mouth of
Hylebos Waterway suggests that a treatment process for organics is an
appropriate component of remedial action. Data from the RI studies (Tetra
Tech 1985a) indicated a trend of decreasing inorganic contamination levels
from the head to the mouth of the waterway. Concentrations of copper and
zinc decreased by approximately 75 percent from the head to the mouth of the
waterway, with a similar though less dramatic pattern for lead. The
presence of relatively low concentrations of inorganic contaminants in the
mouth of Hylebos Waterway is not expected to limit the effectiveness of the
6-20
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organic treatment processes. The solvent extraction process is expected to
be highly effective in removing the PCBs and chlorinated hydrocarbons
predominant in the problem area. Incineration of the organic contaminants
should also be effective.
The land treatment alternative has been eliminated from consideration
based on the low particle affinities exhibited by the contaminants and the
enhanced potential for leaching and migration from the treatment facility.
Similarly, the solidification process is unlikely to be effective in
encapsulating the relatively mobile, Teachable chlorinated hydrocarbons, and
is therefore not evaluated.
The need for periodic dredging to maintain channel depth precludes the
use of in situ capping within the channel boundaries. The potential for
subsequent deepening of the channel to facilitate deeper draft vessels in
the future could also compromise the integrity of a cap in the adjacent
shoreline areas. Therefore, the in situ capping alternative is dropped from
further consideration.
Evaluation of the no-action alternative is required by the NCR to
provide a baseline against which other remedial alternatives can be
compared. The institutional controls alternative, which is intended to
protect the public from exposure to contaminated sediments without imple-
menting sediment mitigation, provides a second baseline for comparison. The
three nontreatment dredging and disposal alternatives are applicable to
remediation of contaminated sediments in the mouth of Hylebos Waterway.
The following seven sediment remedial alternatives are evaluated in
this section for the cleanup of the mouth of Hylebos Waterway:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solvent extraction/upland disposal
• Clamshell dredging/incineration/upland disposal
6.5.2 Evaluation of Candidate Alternatives
The three primary categories of evaluation criteria are effectiveness,
implementability, and cost. A narrative matrix summarizing the assessment
of each alternative based on effectiveness and implementability is presented
in Table 6-3. A comparative evaluation of alternatives is presented in
Table 6-4 based on ratings of high, moderate, and low in seven subcategories
of evaluation criteria. As discussed in Chapter 4, for effectiveness these
6-21
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| EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
ERM PROTECTIVENESS
H
O
0
CONTAMINANT
MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,"
MOBILITY, AND
VOLUME
TABLE 6-3. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE MOUTH OF HYLEBOS WATERWAY PROBLEM AREA
NO ACTION
NA
NA
Original contamination remains.
Source Inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er In the absence of source con-
trol. This alternative is ranked
seventh overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment to xi city and contam-
inant mobilty are expected to
remain at current levels or
Increase as a result of continued
source inputs. Contaminated
sediment volume increases as
a result of continued source
Inputs.
INSTITUTIONAL
CONTROLS
There are no elements of Insti-
tutional control measures that
have the potential to cause
harm during implementation.
There are no elements of insti-
tutional control measures that
nave the potential to cause
harm during implementation.
Source control Is Implemented
and would reduce sediment con-
tamination with time, but adverse
Impacts would persist In the in-
terim.
Access restrictions and moni-
toring efforts can be implement-
ed quickly. Partial sediment re-
covery is achieved naturally, but
significant contaminant levels
persist. Sediment recovery is
improbable within 10 years. This
alternative is ranked sixth over-
all for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxlcity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Removal with dredge
and disposal with downpipe and
diffuser minimizes handling re-
quirements. Workers wear pro-
tective gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment Is
resuspended during dredging
operations. Impacts associated
with disposal of the moderately
soluble chlorinated compounds
are minimized by use of the
clamshell dredge.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
Disposal siting and facility con-
struction may delay project com-
pletion. This alternative is rank-
ed second overall for timeliness.
The long-term reliability of the
cap to prevent contaminant fa-
exposure in a quiescent, sub-
aquatic environment Is consi-
dered good.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota. Protection Is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in
situ conditions.
The toxitify of contaminated^
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM to a barge offshore during
dredging and disposal. Public
access to dredge and disposal
sites is restricted. Public expo-
sure potential is low.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Workers wear pro-
tective gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Nearshore Intertidal habitat
Is tost Contaminated sediment
Is resuspended. Dredge water
can be managed to prevent re-
lease of soluble contaminants.
Dredge and disposal operations
could be accomplished quickly.
Pre-lmplementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment and methods are available.
This alternative is ranked first
for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM.
Varying physicochemical con-
ditions In the fill may Increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment. The
potential for contaminant migra-
tion into marine environment
may increase over CAD. Adja-
cent fish mitigation site is sen-
sitive area. Nearshore site Is
dynamic in nature.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. Altered
condition's resulting from
dredge/disposal operations
may increase mobility of metals.
Volume of contaminated sedi-
ments is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM is confined to a pipeline
during transport Public access
to dredge and disposal sites is
restricted. Exposure from COM
spills or mishandling Is possible.
but overall potential is low.
Hydraulic dredging confines
COM to a pipeline during trans-
port Dredge water contamina-
tion may Increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment Is
resuspended during dredging
operations. Dredge water can
be managed to prevent release
of soluble contaminants.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked third
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM. Al-
though the potential for ground-
water contamination exists, it is
minimal. Migration of chlorinated
hydrocarbons could significant-
ly impact groundwater re-
sources.
Upland disposal is secure, with
negligible potential for environ-
mental Impact if property de-
signed. Potential for ground-
water contamination exists.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may increase due to resuspen-
sion of sediment
CLAMSHELL DREDGE/
SOLVENT EXTRACTION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment, and disposal sites is re-
stricted. Extended duration of
treatment operations may result
In moderate exposure potential.
Additional COM handling asso-
ciated with treatment Increases
worker risk over dredge/disposal
options. Much longer implemen-
tation period. Workers wear pro-
tective gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations.
Bench and pilot scale testing
are required. Full scale equip-
ment Is available. Remediation
could be accomplished within
2 to 3 years. This alternative is
ranked fourth overall for timeli-
ness.
Treated COM low in metals can
be used as inert construction
material or disposed of at a
standard solid waste landfill.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal Perma-
nent treatment for organic con-
taminants is effected
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal Residual
contamination is reduced below
harmful levels.
Effectively destroys or isolates
the predominant organic contami-
nants. Concentrated contami-
nants are disposed of by RCRA-
approved treatment or disposal.
Toxicity and mobility considera-
tions are eliminated. Volume of
contaminated material Is sub-
stantially reduced.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment, and disposal sites Is re-
stricted. Extended duration of
treatment operations may result
In moderate exposure potential.
Additional COM handling assoc-
iated with treatment Increases
worker risk over dredge/disposal-
options. Incineration of COM Is
accomplished over an extended
period of time requiring tempor-
ary storage thereby Increasing
exposure risks. Workers wear
protective gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Sediment Is resuspended
during dredging operations.
Process controls are required
to reduce potential air emis-
sions.
Substantial COM testing and
incinerator installation time are
required before a thermal treat-
ment scheme can be imple-
mented. Remediation could be
accomplished within 2 to 3
years. This alternative is rank-
ed fifth overall for timeliness.
Treated COM low in metals can
be used as inert construction
material or disposed of at a
standard solid waste landfill.
COM containing low levels of
Inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing resdiual
metals may have leaching poten-
tial.
COM containing low levels of in-
organic contaminants may be
rendered nonhazardous. Incin-
eration Is expected to destroy
the organic contaminants.
Treated COM containing residual
metals may have leaching poten-
tial. Volume of contaminated ma-
terial is substantially reduced.
6-22
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| IMPLEMENTABILITY
TECHNICAL FEASIBILITY
INSTITUTIONAL FEASIBILTY
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 6-3.
NO ACTION
Implementation of this alterna-
tive Is feasible and reliable.
No monitoring over and above
programs established under
other authorities Is Implemented.
There are no O 4 M requirements
associated with the no action
alternative.
This alternative is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels in sedimenis are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the intent of CERCLA/
SARA and NCR because of on-
going Impacts.
All materials and procedures are
available.
(CONTINUED)
INSTITUTIONAL
CONTROLS
Source control and institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily Implemented.
Adequate coverage of problem
area would require an extensive
program.
O ft M requirements are minimal.
Some O & M Is associated with
monitoring, maintenance of
warning signs, and issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels In sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
Impacts. State requirements
for source control are achieved.
Coordination with TPCHD for
health advisories for seafood
consumption is required.
All materials and procedures are
available to implement institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment
is reliable. Placement of dredge
and capping materials difficult,
although feasible. Inherent diffi-
culty In placing dredge and cap-
ping materials at depths of 100 ft
or greater.
Confinement reduces monitoring
requirements in comparison to
Institutional controls. Sediment
monitoring schemes can be
readily implemented.
O & M requirements are minimal.
Some O & M is associated with
monitoring for contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Availability of open
water CAD sites is uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
Is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Moni-
toring Implementabillty is en-
hanced compared with CAD.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facil-
ity siting are assumed feasible.
However, disposal of untreated
COM is considered less desir-
able than If COM Is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be ad-
dressed. Alternative complies
with U.S. EPA's onslte disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been iden-
tified and Is currently available.
*
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
Is reliable. Secure upland con-
finement technology is well de-
veloped.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring over CAD. Installa-
tion of monitoring systems is
routine aspect of facility siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Coordination is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
COM Is considered less desir-
able than If COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currency available.
CLAMSHELL DREDGE/
SOLVENT EXTRACTION/
UPLAND DISPOSAL
Although still In the develop-
mental stages, sludges, sons.
and sediments have success-
fully been treated using thfs
technology.
Monitoring Is required only to
evaluate the reestabllshment
of benthic communities. Moni-
toring programs can be readily
Implemented.
No O a M costs are Incurred at
the conclusion of COM treat-
ment System maintenance Is
intensive during implementation.
Approvals depend largely on re-
sults of pilot testing and the na-
ture of treatment residuals.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be ad-
dressed. Complies with policies
for permanent reduction in con-
taminant mobility. Requires
RCRA permit for disposal of con-
centrated organic waste.
Process equipment available.
Disposal site availability is not a
primary concern because of re-
duction in hazardous nature of
material.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Incineration systems capable of
handling COM have been de-
veloped, but no applications In- '
voMng COM have been report-
ed. Effects of salt and moisture
content must be evaluated.
Disposal site monitoring Is not
required if treated COM Is deter-
mined to be nonhazardous. Air
quality monitoring Is Intensive
during Implementation.
No O & M costs are Incurred at
the conclusion of COM treat-
ment System maintenance Is
Intensive during implementation.
Approvals for incinerator opera-
tion depend on pilot testing and
ability to meet air quality stan-
dards.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be ad-
dressed. Complies with policies
for permanent reduction in con-
taminant toxicity and mobility.
Requires compliance with
PSAPCA standards.
Incineration equipment can be
installed onslte for COM re-
mediation efforts. Applicable
incinerators exist. Disposal site
availability Is not a concern be-
cause of reduction In hazardous
nature of material.
6-23
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TABLE 6-4. EVALUATION SUMMARY FOR MOUTH OF HYLEBOS WATERWAY
No Action
Short-Term
Protect iveness Low
Timeliness Low
Long-Term
Protecti veness Low
Reduction in
Toxicity, Mobility,
or Vol ume Low
Technical
Feasibility High
Institutional
Feasibility Low
Availability High
Long-Term Cleanup
Goal Cost3
Capital
O&M
Total
Long-Term Cleanup Goal
with 10-yr
Recovery Cost3
Capital
O&M
Total
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
1,986
1,992
6
1,223
1,229
Clamshell/
CAD
Moderate
Moderate
High
Low
Moderate
Moderate
Moderate
6,457
738
7,195
1,773
289
2.062
Clamshell/
Nearshore
Disposal
Moderate
High
Moderate
Low
High
Moderate
High
19,524
898
20,422
5,597
336
5,933
Hydraul ic/
Upland
Oi sposal
Moderate
Moderate
Moderate
Low
High
Moderate
Moderate
34,688
1,410
36,098
10,013
475
10,488
Clamshell/
Extraction/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
166,372
1,334
167,706
48,568
453
49.021
Cl amshel 1 /
Incinerate/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
377,885
1,334
379,219
110,461
453
110.914
All costs are in $1,000.
6-24
-------
subcategories are short-term protectiveness; timeliness; long-term protec-
tiveness; and reduction in toxicity, mobility, or volume. For implementa-
bility the subcategories are technical feasibility, institutional feasi-
bility, and availability.- Capital and O&M costs are also presented in
Table 6-4. Remedial costs are shown for two sediment cleanup scenarios. The
long-term cleanup*goal and cost presented refers to the costs associated
with remediation of all sediments currently exceeding'the long-term cleanup
goal. The long-term cleanup goal 10-yr recovery cost shown refers to the
costs associated with remediation of sediments that would be expected to
exceed the cleanup goal 10 yr after implementing source controls and
allowing natural recovery to occur.
Short-Term Protect!veness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
biological and potential public health impacts would continue with the
contaminated sediments remaining in place. Source control measures initiated
as part of the institutional controls would tend to reduce sediment
contamination with time, but adverse impacts would persist in the interim.'
r •
«, All other alternatives received a moderate rating. . The clamshell
dredging/nearshore disposal alternative is rated moderate for short-term
protectiveness primarily because nearshore intertidal habitat would be lost
in siting the disposal facility. While the loss of habitat due to nearshore
site development in Commencement Bay may be mitigated by requiring habitat
enhancement in' a nearby area, the availability of sites with potential for
habitat enhancement is limited. The confinement of contaminated dredged
material to a barge offshore during dredging and disposal, and the availabi-
lity of means for adequately protecting workers during implementation
assures a low level of,human health hazards. The confined aquatic disposal
option .is also rated moderate for this criterion because of potential water
quality"impacts associated with disposal of the moderately soluble chlorin-"
ated hydrocarbons compounds present. Use of the clamshell dredge to
maintain in situ densities followed by deposition of a cohesive mass of
sediment'with the split-hulled barge should aid in minimizing this potential.
The hydraulic dredge/upland disposal alternative is also rated as moderate
in this subcategory because of the potential for solubilizing the chlorinated
hydrocarbons in the dredge slurry. Alternatives involving treatment
received moderate ratings for short-term protectiveness because all involve
additional dredged material handling, longer implementation periods, and
increased • air emissions, which potentially increase worker and public
exposure.
Timeliness--
The no-action and institutional controls alternatives received low
ratings for timeliness. With no action, sediments would remain unacceptably
contaminated, source inputs would continue, and natural sediment recovery
would be unlikely. Source inputs would be controlled under the institutional
controls alternative but, as discussed in Section 6.3.2, sediment recovery
6-25-
-------
based on the indicator contaminants PCBs and hexachlorobenzene is improbable
within 10 yr.
Moderate ratings were assigned to all other alternatives except
clamshell dredging/nearshore disposal. Approvals and construction of upland
or open water confined aquatic disposal sites are estimated to require a
minimum of 1-2 yr. Equipment and methods used require no development
period, and pre-implementation testing is not expected to be extensive.
These factors indicate that the upland and confined aquatic disposal
alternatives can be accomplished in a shorter period of time than if
treatment is involved. The solvent extraction and incineration alternatives
are likely to require a period of extensive testing before being accepted
for implementation. Once approval is obtained, treatment of the contaminated
sediments in the mouth of Hylebos Waterway to long-term goals will require a
period of approximately 2-3 yr, assuming maximum treatment rates of
420 yd3/day (see Section 3.1.5).
The clamshell dredging/nearshore disposal alternative is rated high for
timeliness. Pre-implementation testing and modeling may be necessary to
evaluate potential partitioning to the water column of the contaminants
associated with these sediments. However, such testing is not expected to
require an extensive period of time. Equipment and methods are readily
available, and disposal siting issues are not likely to delay implementation.
Long-Term Protectiveness--
The evaluation for long-term protectiveness resulted in low ratings for
the no-action and institutional controls alternatives because the timeframe
for sediment recovery is extensive. For the latter alternative, the
potential for exposure to contaminated sediments remains, albeit at declining
levels following implementation of source controls. The observed adverse
biological impacts would continue.
Moderate ratings were assigned to the clamshell dredging/nearshore and
hydraulic dredging/upland disposal alternatives because of the relatively
high potential for migration of the chlorinated hydrocarbon compounds. In
addition, the impacts of the chlorinated organics on groundwater resources
in the upland environment would be significant if the contaminants migrated
from the confinement facility. Although the structural reliability of the
nearshore facilities is regarded as good, the nearshore environment is
dynamic in nature (i.e., from wave action and tidal influences). Release of
the soluble organic contaminants from the disposal site could result in
significant environmental damage, given the proximity of a fish habitat
mitigation area (located in the outer slip of Blair Waterway) to the
potential disposal area.
Both alternatives involving treatment received high ratings primarily
because the treatment processes would result in the effective removal or
destruction of organic contaminants. For both alternatives, the treated
solids could be confined in a minimum standards municipal landfill, assuming
that the material is determined to be nonhazardous. The small volume of
concentrated hazardous residue resulting from the solvent extraction process
6-26
-------
would be incinerated and the material collected from participate collection
systems during incineration would require disposal in an RCRA-approved
facility. The confined aquatic disposal alternative is also rated high for
long-term protect!veness. Isolation of contaminated material in the
quiescent, subaquatic environment would provide a high degree of protection,
with little potential for exposure of sensitive environments to contaminated
sediments. Confinement under nearly in situ conditions would maintain the
physicochemical conditions of contaminated sediments, thereby minimizing
potential contaminant migration.
Reduction in Toxicity, Mobility, or Volume--
Low ratings were assigned to all alternatives under this criterion,
except those involving treatment. Although confined aquatic disposal,
upland, and nearshore disposal alternatives isolate contaminated sediments
from the surrounding environment, the chemistry and toxicity of the material
itself would remain largely unaltered. Without treatment, the toxicity of
contaminated sediments would remain at preremediation levels. Contaminated
sediment volumes would not be reduced, and may actually increase with the
hydraulic dredging option because the material would be suspended in an
aqueous slurry.
Alternatives involving the solvent extraction and incineration treatment
processes would effectively destroy or isolate the predominant organic
contaminants, and therefore received high ratings. The solvent extraction
process would change the chemical status of the metals by providing the
alkaline conditions necessary for insoluble hydroxide formation. Incinera-
tion is expected to destroy the organic contaminants.
Technical Feasibility--
The two alternatives involving treatment received moderate ratings for
technical feasibility because the treatment processes have never been
applied to sediment remediation. All processes are believed to be suitable
for application to the organic contaminants, but lack of experience and
demonstrated performance in the use of these processes for treatment of
contaminated dredged material warrants caution. Extensive bench-scale
testing is likely to be required before treatment via solvent extraction or
incineration could be implemented. The difficulty inherent in placing
dredge and capping materials at depths of 100 ft or greater requires that a
moderate rating be assigned to the confined aquatic disposal alternative, as
well.
High ratings are warranted for the remaining alternatives because the
equipment, technologies, and expertise required for implementation have been
developed and are readily accessible. The technologies constituting these
alternatives have been demonstrated to be reliable and effective in the past
for similar operations.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
6-27
-------
feasible, and similar methods are applied for all alternatives. The
intensity of the monitoring effort, which varies with uncertainty about
long-term reliability, does not influence the feasibility of implementation.
Institutional Feasibility--
The no-action and institutional controls alternatives were assigned low
ratings for institutional feasibility because compliance with CERCLA/SARA
mandates would not be achieved. Requirements for long-term protection of
public health and the environment would not be met by either alternative.
Moderate ratings were assigned to the remaining alternatives because of
potential difficulty in obtaining agency approvals for siting and development
of disposal sites or for implementation of treatment technologies. Although
several potential confined aquatic and upland disposal sites have been
identified in the project area, significant uncertainty remains with the
actual construction and development of the sites. Although excavation and
disposal of untreated, contaminated sediment is discouraged under Section
121 of SARA, properly implemented confinement should meet requirements for
public health and environmental protect!veness. Agency approvals are
assumed to be contingent upon a bench-scale demonstration of effectiveness.
Availability--
Sediment remedial alternatives that can be implemented using existing
equipment, expertise, and disposal or treatment facilities received high
ratings for availability. The no-action and institutional controls
alternatives can be implemented using available equipment and expertise, and
received a high rating for this criterion. It was assumed that the Blair
Waterway Slip 1 would be available as a nearshore disposal site, making the
clamshell dredge/nearshore disposal alternative readily implementable.
Remedial alternatives that involve confined aquatic disposal or upland
disposal of untreated sediments are rated moderate because of the uncertainty
associated with disposal site availability. Candidate alternatives were
developed by assuming that confined aquatic and upland sites would be
available. However, no sites for contaminated sediments are currently
approved for use and no sites are currently under construction. For costing
purposes, development of a RCRA-equivalent upland site within the project
boundaries was assumed. Depending on the final characterization of
sediments, upland disposal in an existing municipal or demolition landfill
may also be feasible. A moderate rating has also been assigned to the two
dredging/treatment/upland disposal alternatives, in part because of the same
uncertainties regarding disposal site availability and because of uncertain-
ties regarding equipment availability. However, testing conducted as a part
of the bench-scale treatability and performance evaluation for the treatment
processes should confirm that the products are nonhazardous and suitable for
a standard solid waste management facility. For costing purposes, it was
assumed that all but the small volume of extraction residue and incineration
fly ash would be disposed of in a standard solid waste management facility
in the project area.
6-28
-------
Cost--
Capital costs increase with increasing complexity (i.e., from no action
to the treatment options). This increase reflects the need to site and
construct disposal facilities, develop treatment technologies, and implement
alternatives requiring extensive contaminated dredged material or dredge
water handling. Costs for hydraulic dredging/upland disposal are signi-
ficantly higher than those for clamshell dredging/nearshore disposal,
primarily because of underdrain and bottom liner installation, dredge water
clarification, and use of two pipeline boosters to facilitate dredged
material transport to the upland site. The cost of conducting the extraction
and incineration treatment alternatives increases as a result of material
costs for the process, siting and construction of treatment facilities, and
labor costs for material handling and transport. Dewatering and dredge
water management costs are also incurred for the incineration option.
A major component of O&M costs is the monitoring requirements associated
with each alternative. The highest monitoring costs are associated with
alternatives involving the greatest degree of uncertainty for long-term
protectiveness (e.g., institutional controls) or where extensive monitoring
programs are required to ensure long-term performance (e.g., confined
aquatic disposal). Estimated costs for monitoring of the confined aquatic
disposal facility are also significantly higher because of the need to
collect sediment core samples at multiple stations, with each core being
sectioned to provide an appropriate degree of depth resolution. Nearshore
and upland disposal options, on the other hand, use monitoring well networks
requiring only the collection of a single groundwater sample from each well
to assess containment migration.
It was also assumed that the monitoring program will include analyses
for all problem chemicals (i.e., those exceeding long-term cleanup goals)
identified in the mouth of the waterway. This approach is conservative and
could be modified to reflect use of key chemicals to track performance.
Monitoring costs associated with the treatment alternatives are significantly
lower because the processes result in lower contaminant migration potential.
All unit costs and assumptions are presented in Appendix D.
6.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the seven candidate sediment
remedial alternatives for the mouth of Hylebos Waterway, clamshell dredging
with confined aquatic disposal has been recommended as the preferred
alternative for sediment remediation. Because sediment remediation will be
implemented according to a performance-based ROD, the specific technologies
identified in this alternative (i.e., clamshell dredging, confined aquatic
disposal) may not be the technologies eventually used to conduct the
cleanup. New and possibly more effective technologies available at the time
remedial activities are initiated may replace the alternative that is
currently preferred. However, any new technologies must meet or exceed the
performance criteria (e.g., attainment of specific cleanup criteria)
specified in the ROD. The confined aquatic disposal alternative is
currently preferred for the following reasons:
6-29
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• The alternative protects human health and the environment by
effectively isolating contaminated sediments at near in situ
conditions in a quiescent, subaquatic environment
• Confined aquatic disposal is technically feasible and has
been demonstrated to be effective in isolating contaminated
sediments
• The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 401 and 404 of the Clean Water Act,
and other applicable environmental requirements
• Performance monitoring can be accomplished effectively and
implemented readily
• The volume of contaminated sediment requiring remediation
(approximately 230,000 yd3) is compatible with the available
capacity of the tentatively identified confined aquatic
disposal facilities within the Commencement Bay area
• The potential mobility of the relatively soluble organic
contaminants can be minimized with mechanical dredging and
split-hulled barge disposal techniques and capping in the
subaquatic environment
• Potentially mobile chlorinated hydrocarbons, if placed in the
nearshore environment, could be subject to leaching, which in
turn could affect the sensitive fish habitat mitigation area
adjacent to the proposed nearshore fill area in Blair Waterway
• The costs of developing an upland facility that is protective
of groundwater resources are not warranted considering the
levels of contamination and high bulk of sediments in the
mouth of Hylebos Waterway
• Costs are $3.9 million less than those of the nearshore
disposal alternative and over $8 million less than the
hydraulic dredge/upland disposal alternative.
Clamshell dredging with confined aquatic disposal is rated high for
long-term protectiveness and moderate for all other criteria, except
reduction in toxicity, mobility, or volume, for which it is rated low.
Implementation can be coordinated with similar sediment remediation
activities in City Waterway, Wheeler-Osgood Waterway, and the Ruston-
Pt. Defiance Shoreline. This alternative can be implemented within
approximately 1-2 yr with available equipment that has proven effective in
past similar operations. Implementation of the confined aquatic disposal
alternative is contingent upon the siting and development of an open-water
disposal site. This alternative is also cost-effective (see Table 6-4).
6-30
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Leachate tests conducted on PCB-contaminated sediments in Indiana
Harbor (U.S. Army Corps of Engineers 1987) revealed that contaminant release
from compression settling was considerably lower than that from elutriate
testing. Those findings suggest that mechanical dredging and bulk placement
of contaminated sediments into the confinement facility would minimize
release at the disposal site. The investigators also cited the need to
modify the clamshell dredge by enclosing the clamshell bucket to minimize
sediment resuspension.
Performance monitoring associated with the development of the confined
aquatic disposal facility would be expected to provide sufficient warning of
contaminant migration. Corrective actions (e.g., cap and berm repairs)
could be implemented before adverse effects occur.
Although some sediment resuspension is inherent in dredging operations,
silt curtains, clamshell bucket modifications, and other available engineer-
ing controls would be expected to minimize adverse impacts associated with
redistribution. The impacts of dredging on water quality criteria can be
predicted by using data from bench-scale tests to estimate chlorinated
hydrocarbon contaminant partitioning to the water column. Some interstitial
water loss during lift through the water column and in potential dewatering
during transport would be expected. However, compared to hydraulic dredging,
reduced disturbance and the absence of a slurry should result in less
opportunity for contaminants to go into solution (Phillips et al. 1985).
(PCB contaminants are expected to exhibit a higher particle affinity.)
Production rates of clamshell dredges vary significantly depending on the
nature of sediments and size of the bucket. However, based on the estimated
230,000 yd^ of sediment requiring remediation, this alternative can be
implemented in a reasonable timeframe. Seasonal restrictions on dredging
operations to protect migrating anadromous fish are not expected to pose a
problem. Dredging activities within this area are consistent with the
Tacoma Shoreline Management Plan and Sections 404 and 401 of the Clean Water
Act. Close coordination with appropriate federal, state, and local regula-
tory personnel will be required prior to undertaking remedial actions.
The nearshore disposal alternative was not selected because the volume
of material is more compatible with confined aquatic disposal. The Blair
Waterway Slip 1 nearshore fill area is not large enough to accommodate all
contaminated sediments in the Commencement Bay Nearshore/Tideflats (N/T)
area, nor is it appropriate for the contaminants in all sediments. Although
confined aquatic disposal cannot be implemented as quickly as nearshore
disposal at an available site, it offers a similar degree of protection at a
lower cost.
The two alternatives for treatment of organic contaminants in the mouth
of Hylebos Waterway are also feasible. Implementation of the solvent
extraction alternative would require bench-scale and possibly pilot-scale
testing of contaminated sediments. Implementation of the thermal treatment
alternative would require test burns to establish destruction efficiency.
In addition, potential air quality impacts would need to be addressed. The
low Btu value of the sediments should necessitate use of an energy-intensive
process. This factor is largely responsible for the extremely high cost
6-31
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associated with implementing the thermal treatment alternative (greater
than $110 million).
Although the treatment options would result in destruction of organics,
confined aquatic disposal of sediments should offer sufficient long-term
protection, given the concentrations in the problem area. The cost
associated with the two treatment options evaluated are approximately
24 (solvent extraction) and 54 (incineration) times as great as that of the
confined aquatic disposal alternative. The additional expense associated
with the performance achieved by implementing the treatment options does not
appear warranted.
The hydraulic dredging/upland disposal option was not chosen as the
preferred alternative because of uncertain disposal site availability and
the policy bias against landfilling untreated contaminated materials.
Although this alternative is feasible from both a technical and institutional
standpoint, the risks of system failures for a disposal site in the upland
environment (e.g., groundwater risks) compromise the desirability of this
alternative.
The no-action and institutional controls alternatives were not selected
since their implementation would not meet long-term cleanup goals.
6.7 CONCLUSIONS
The mouth of Hylebos Waterway was identified as a problem area because
of the elevated concentrations of organic and inorganic contaminants in
sediments. PCBs and hexachlorobenzene were selected as indicator chemicals
to assess source control requirements, evaluate sediment recovery, and
estimate the area and volume to be remediated. In this problem area,
sediments with concentrations currently exceeding long-term cleanup goals
cover an area of approximately 393,000 yds with a volume of 786,000 yd3.
Some of this sediment is expected to recover within 10 yr following
implementation of all known, available, and reasonable source control
measures, thereby reducing the contaminated sediment volume by 556,000 yd3.
The total volume of sediment requiring remediation is, therefore, reduced to
230,000 yd3.
The primary identified source of problem chemicals to the mouth of
Hylebos Waterway is the Occidental Chemical Corporation facility. Source
control measures required to correct the identified problems at the facility
and ensure the long-term success of sediment cleanup in the problem area
include the following actions:
• Reduce the amount of chlorinated hydrocarbons that are
present in the groundwater and that discharge to the waterway
• Continue monitoring the outfall at the Occidental Chemical
main plant, and implement additional control technologies, if
necessary
6-32
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• Conduct additional source investigations to identify any
ongoing sources of PCB contaminants in the area, and initiate
additional source control measures as necessary
• Confirm that all significant sources of problem chemicals
have been identified and controlled
• Implement regular sediment monitoring to confirm sediment
recovery predictions, and address the adequacy of source
control measures.
It should be possible to control sources sufficiently to maintain
acceptable long-term sediment quality. This determination was made by
comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. However, the level of source control required for PCBs was
estimated to be approximately 86 percent compared to the technically
feasible level of approximately 60 percent. The estimated source control
required for hexachlorobenzene was similar to levels considered to be
technically achievable. Additional evaluations to refine these estimates
will be required as part of the source control measures described above.
Source control requirements were developed through application of the
sediment recovery model for the indicator chemicals PCBs and hexachloro-
benzene. The assumptions used in determining source control requirements
were environmentally protective. It is anticipated that more detailed
loading data will demonstrate that sources can be controlled to the extent
necessary to maintain acceptable sediment quality. If the potentially
responsible parties demonstrate that implementation of all known, available,
and reasonable control technologies will not provide sufficient reduction in
contaminant loadings, then the area requiring sediment remediation may be re-
evaluated.
Clamshell dredging/confined aquatic disposal was recommended as the
preferred alternative for remediation of sediments not expected to recover
within 10 yr following implementation of all known, available, and reasonable
source control measures. The selection was made following a detailed
evaluation of viable alternatives encompassing a wide range of general
response actions. Because sediment remediation will be implemented
according to a performance-based ROD, the alternative eventually implemented
may differ from the currently preferred alternative. The preferred
alternative meets the objective of providing protection for both human
health and the environment by effectively isolating contaminated sediments
at near in situ conditions in a quiescent, subaquatic environment. Confined
aquatic disposal has been demonstrated to be effective in isolating
contaminated sediments (U.S. Army Corps of Engineers 1988). The alternative
is consistent with the Tacoma Shoreline Management Plan, Sections 404 and
401 of the Clean Water Act, and other applicable environmental requirements.
As indicated in Table 6-4, clamshell dredging/confined aquatic disposal
provides a cost-effective means of sediment mitigation. The estimated cost
to implement this alternative for sediment that exceeds long-term goals
following 10 yr of recovery is $1,773,000. The present worth of 30 yr of
6-33
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environmental monitoring and other O&M at the disposal site is estimated to
be $289,000. These costs include long-term monitoring of sediment recovery
areas to verify that source control and natural sediment recovery have
corrected the contamination problems in the recovery areas. The total
estimated present worth of preferred alternative is $2,062,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control
Limited information
associated costs.
on disposal site availability and
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• ' Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures
• Final selection of a disposal site.
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
and regulations, utilize the most protective solutions practicable, and are
cost-effective.
6-34
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7.0 SITCUM WATERWAY
Potential remedial actions are defined and evaluated in this section
for the Sitcum Waterway problem area. The waterway is described in
Section 7.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 7.2 provides an overview of contaminant
sources, including site background, identification of known and potential
contaminant reservoirs, remedial activities, and current site status. The
effects of source control measures on sediment contaminant concentrations
are discussed in Section 7.3. Area and volume of sediments requiring
remediation are discussed in Section 7.4. The detailed evaluation of
candidate sediment remedial alternatives chosen for the problem area and
indicator problem chemicals is provided in Section 7.5. The preferred
alternative is identified in Section 7.6. The rationale for its selection
is presented, and the relative merits and deficiencies of the remaining
alternatives are discussed. The discussion in Section 7.7 summarizes the
findings of the selection process and integrates required source control
with the preferred remedial alternative.
7.1 WATERWAY DESCRIPTION
Sitcum Waterway is a deep navigational waterway with a required
maintenance depth of 35-40 ft below MLLW. An illustration of the waterway
and the locations of storm drain outfalls and nearby industries is presented
in Figure 7-1. It is not known when Sitcum Waterway was first created from
the tideflats of the Puyallup River. Photographs dating back to 1923 show
the waterway to be approximately twice its current width. A series of
dredge and fill projects conducted since 1946 have shaped Sitcum Waterway
into its present configuration (Tetra Tech 1986c). Material dredged from the
waterway for maintenance was used to fill the north shore of the original
channel, on which the Port of Tacoma Terminal 7 is presently located. The
Port of Tacoma owns all of the property .surrounding Sitcum Waterway, which is
currently used for storage, shipping, and receiving facilities (Tetra Tech
1986c). Additional detail on land use activities is presented in Sec-
tion 7.2.
7.1.1 Nature and Extent of Contamination
An examination of sediment contaminant data obtained during RI/FS
sampling efforts (Tetra Tech 1985a, 1985b, 1986c) and historical surveys has
revealed that the waterway contains elevated concentrations of both organic
and inorganic chemicals. No Priority 1 contaminants were identified for the
waterway. However, arsenic, copper, lead, and zinc were identified as
Priority 2 contaminants. The following organic compounds exceeded their
corresponding AET value at only one station sampled and are therefore
considered Priority 3 contaminants: low molecular weight polynuclear
7-1
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SI-165
1 PORT OF TACOMA TERMINAL 7
2 WORLD TRADE CENTER
3 IANCO. INC.
TACOMA-PORT ANGELES
ALTO FREIGHT. NC.
COLE SCREENPRNT NC.
SHORTTSAW&KNFE
KAMAN BEARNG & SUPPLY
HERTZ EOUFMENT RENTAL
BARNACLE BITS TAVERN
BARTHEL CHEMICAL CONSTRUCTION CO.
TRANSCON
McKENZEFUaCO.
TACOMA FIRE DEPT. #12
FASTCO INC.
DRURYCO.
SATURN CO.
TRADE NDUSTRES
PARGAS OF TACOMA
SOUND BATTERY
PUGET SOUND NATIONAL BANK
GEORGIA PACFC
(RELOCATED N FEDERAL WAY)
LUNDGREN DEALERS SUPPLY tC.
7 MANN-RUSSELL ELECTRONICS
8 CONCRETETECHNCLOGY
9 GENERAL HARDWAFO
10 PACFC STORAGE. NC
11 UOUOAR PRODUCTS
12 TACOMA MARINE SERVICES
13 RHEEMMFG.CO.
14 PORTOFTACOMA
(CASCADE TMBER • LOG SORTMG YARD)
15 PLATT ELECTRO CO.
TIMCO, NC.
LANDSCAPE BARK
JONES-WASH. STEVEDORING
ERDAH.TRUCKNG
16 NORTVfWESTWRE&ROPEEQUf'MENT
17 BENNETT STAMPNG AND TOO. CO.
18 PUREXCORP.
NPDESWA0001589
19 RYDERPEFREGHTTERMNAL
X NuLFEFERTUZER
21 GEORGK-PACFCRESMS
NPDESWA0038601
22 CERTAN-TEED PRODUCTS CORP.
23 WOODLAM.NC.
24 NuLFEFERTUZER
25 ALLED CHEMICAL CORP.
26 KAISER ALLUMNUM WAREHOUSE
27 NORECOREPLASTCS.NC.
28 SHAU&eUJSONCO.
29 BROWN&HALEY
X PORTOFTACOMA
(LEASED TO SEALAND)
Reference: Taooma-Pierce County Health
Department (1984,1966).
Notes: Property boundaries are approximate
based on aerial photographs and drive-
by inspections.
meters
300
Figure 7-1. Sitcum Waterway - Existing industries, businesses, and
discharges.
7-2
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aromatic hydrocarbons (LPAH), high molecular weight polynuclear aromatic
hydrocarbons (HPAH), an alkylated benzene isomer, a diterpenoid hydrocarbon,
and N-nitrosodiphenylamine.
Concentrations of copper, zinc, lead, and arsenic were found to be
elevated along the entire length of the waterway with especially high
concentrations of the first three metals near the head (northeast corner,
Tetra Tech 1985a) and along the northeast embankment. No clear trends in the
spatial distribution of metal contaminants were observed and past dredging
activity did not appear to account for the erratic distribution.
Copper and arsenic were selected as indicator chemicals for Sitcum
Waterway. Surface sediment enrichment ratios (i.e., ratio of observed
concentration to long-term cleanup goal) for these two contaminants were
higher over a greater area than those for either of the other two metals.
These contaminants were also selected as indicators on the basis that they
represent contaminant loading to the waterway from ore spillage and storm
drains (see Section 7.2.1).
Areal and depth distributions of copper and arsenic in Sitcum Waterway
are presented in Figures 7-2 and 7-3, respectively. Levels of contamination
indicated in the figures are normalized to cleanup goals (i.e., presented as
enrichment ratios), which are 390 mg/kg for copper and 57 mg/kg for arsenic.
Problem sediments are defined by values greater than 1.0. The cleanup goal
for copper was set by the AET value derived for oyster larva bioassay, and
the cleanup goal for arsenic was set by the AET value derived for benthic
infaunal abundance depression. In addition, exceedances of amphipod and
benthic AET for two Priority 3 organic compounds were noted at Station SI-12
(see Appendix F for location).
Included in Figures 7-2 and 7-3 are contaminant depth profiles obtained
from two core samples. Subsurface maxima were observed for both copper and
arsenic, indicating that inputs were historically greater than are observed
currently. Data from core SI-91, which was obtained from the heavily
contaminated northeast corner of the waterway, illustrate that contamina-
tion with depth is extensive. For the purpose of estimating the volume of
sediment exceeding copper and arsenic cleanup goals, remediation to a depth
of 1 yd was assumed (see SI-91 profile).
7.1.2 Recent and Planned Dredging Pro.iects
The Port of Tacgma has requested a dredging permit for removal of
approximately 2,000 yd3 of material (U.S. Army Corps of Engineers, 27 October
1987, personal communication). The majority of this material lies along the
southern side of the channel approximately midway up the waterway. These
dredging plans were initially developed based on complaints from pilots.
However, the complaints have ceased recently and the proposed shoal
dredging plans have been put on hold (White, M., 15 April 1988, personal
communication).
The Port of Tacoma has also formulated plans for conducting two pier
extension projects in Sitcum Waterway. One of those projects is slated for
7-3
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COPPER (mg/kg)
§ § §
o 8 I I 8 5
11 I L
0123
RATIO TO CLEANUP OOAL
SI-91
• SI-92
MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1084 (1979-1981)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
SI-91
Figure 7-2. Areal and depth distributions of copper in sediments of
Sitcum Waterway, normalized to long-term cleanup goal.
7-4
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ARSENIC (mg/kg)
0 50 100 150 200 250 300 350 400
0123456"
RATIO TO CLEANUP GOAL
MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
SI-91
Figure 7-3. Areal and depth distributions of arsenic in sediments of
Sitcum Waterway, normalized to long-term cleanup goal.
7-5
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Pier 7d at the port's ore unloading facility on the north side of the
waterway. The volume of material to be dredged is unclear at this time,
but is estimated to be from 40,000 to 100,000 yd-3 (Sacha, L., 16 November
1988, personal communication). This project entails extending the existing
pier at the mouth of the waterway (north shore) approximately 250 ft toward
the bay, parallel to the existing shoreline (White, M.( 15 April 1988,
personal communication). This project is tentatively scheduled for 1989,
and no permits had been applied for the work as of November 1988. Based on
available information, the project does not appear to impact the sediment
problem area defined for the waterway.
The second pier extension project involves a 400-ft pier extension
along the south side near the mouth of the waterway. This project will
require dredging of approximately 40,000 yd3 of sediment. The project is
scheduled for 1989 and all permit approvals except those from the U.S. Army
Corps of Engineers have been received. The south side pier extension
project also includes a habitat replacement component, in which the southwest
corner at the head of the waterway will be filled with clean sediment to
create new intertidal habitat. The surface area of this new habitat will be
approximately 50 percent of that removed for the pier extension. Two storm
drain outfalls discharging in the location of the proposed new habitat will
be extended underneath the mitigation area. Both the pier and the habitat
replacement components of the pier extension project will disturb sediments
defined as contaminated in this report.
7.2 POTENTIAL SOURCES OF CONTAMINATION
All land surrounding Sitcum Waterway is owned by the Port of Tacoma.
The south shore is leased to Sea-Land for storage, shipping, and receiving
facilities. An office building at the head of the waterway has housed the
Port of Tacoma executive offices since 1982. The Port of Tacoma's Terminal 7
occupies the north waterfront, with facilities for container handling and
bulk unloading of alumina, lead, copper, and zinc. Ore unloading facilities
are leased to Kaiser Aluminum (Carter, S.( 22 September 1987, personal
communication). Former occupants of the waterfront property include lumber
and wood products industries, railroad yards, and oil storage facilities.
As shown in Figure 7-1, a large, high-density industrial/commercial
area lies southeast of the waterway. Stormwater runoff from this area
discharges to Sitcum Waterway via storm drain SI-172. Several other storm
drains service the waterway [e.g., SI-717 (Terminal 7), SI-176 (Sea-Land)].
Emergency overflow from a sanitary sewer pump station also discharges via
SI-176.
Table 7-1 provides a summary of problem chemical and source status
information for the area. The high concentrations of metals at the head of
the waterway have been attributed primarily to storm drains, particularly
storm drain SI-172. The Port of Tacoma ore unloading facility has also been
identified as a major contaminant source associated with the inorganic
contaminants in the sediments of Sitcum Waterway. When input of metals as
estimated from source loading data is compared to that as estimated from
sediment concentrations, the values are within 1 order of magnitude,
7-6
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TABLE 7-1. SITCUM WATERWAY - SOURCE STATUS3
Chemical /Group
Copper
Lead
Zinc
Arsenic
LPAH
HPAH
Oibenzofuran
N-n1trosod1phenylamine
Dlterpenold hydrocarbon
Alky la ted benzene i sorter
Chemical
Priority1*
2
2
2
2
3 (EPA Sta. 3)
3 (EPA Sta. 3)
3 (SI-14)
3 (SI-12)
3 (SI-12)
3 (SI-11)
Sources
Port of Tacoma
ore docks
Storm drains
Past oil spills
Fire at Tacoma
Boat (1970s)
Unknown
Unknown
Storm drains
Source ID
Yes
Yes
Potential
Potential
No
No
Potential
Source Loading
No
Yes
SI-172 and SI-176 accounted
for approximately 65% of
copper, lead, and zinc
and approximately 95X of
arsenic
No
No
Inadequate data
No
No
Source Status
Ongoing
Ongoing
Historical
Historical
Historical
Historical
Unknown
Sediment Profile Trends
Slight surface minima
Variable
Surface minimum
c
c
a Source information and sediment Information blocks apply to all chemicals in the
respective group, not to individual chemicals only.
b For Priority 3 chemicals, the station exceeding AET 1s noted In parentheses.
c Not evaluated for this study.
-------
indicating that no important data gaps exist in accounting for the major
sources of metals to the waterway (Tetra Tech 1985b). The elevated
concentrations of LPAH, HPAH, and dibenzofuran that were observed have
tentatively been attributed to historical sources (i.e., past oil spills and
a fire at Tacoma Boat in the 1970s) (Tetra Tech 1985a).
7^.2.1 Port of Tacoma Terminal 7 Ore Unloading Facilities
The Port of Tacoma Terminal 7 ore unloading facilities are located
along the entire north shore of Sitcum Waterway. Four berths are available
for mooring freighters along a 2,700-ft pier.
Ore unloading is a small part of the Terminal 7 freight handling
operations. Alumina shipments arrive approximately once per month and repre-
sent 65 percent of all the ore handled. Alumina itself contains zinc,
copper, and lead at concentrations between 1 and 10 mg/kg (Norton and
Johnson 1985b). Lead ore concentrate represents 20 percent and ores of
copper and zinc combined represent the remaining 15 percent of the volume of
ores handled at Terminal 7 (Carter, S., 25 September 1987, personal communi-
cation). Between 1973 and 1983, alumina passed through the Terminal 7
facilities at an average yearly rate of 520,000 mt/yr.
Alumina handled at Terminal 7 is transferred from shipboard to a closed
hopper in a 25-yd^ bucket sealed to minimize ore loss. A closed conveyor
system carries the ore to two storage domes with a combined capacity of
136,000 mt. (The domes were built in 1966 and 1968.) Other ore types are
loaded in 3- or 6.5-yd^ buckets directly into open rail cars for shipment
offsite. Ore spillage can occur during the unloading process but is more
likely to be a problem with ores other than alumina because of the special
sealed bucket used for unloading this material. In the past, spilled ore
was recovered to the extent that was practical and the remaining material
was washed into the waterway (Norton and Johnson 1985b).
Terminal 7 ore unloading facilities were identified as sources of
metals based on the proximity of the facilities to the observed contamination
and on the documented use and handling practices of the compounds of concern.
Identification of Contaminant Sources Onsite--
Contaminant sources onsite include the ore materials that are unloaded
at the facility and surfaces where spilled ore may have accumulated. These
sources have the potential to contaminate stormwater runoff which enters the
waterway through storm drains. Storm drains serving the area are described
in Section 7.2.2.
Loading Data--
Loading data for the drain under Terminal 7 (i.e., SI-717) are available
for a single storm event (on 26 June 1984). Measured loadings for arsenic,
copper, lead, and zinc are presented in Appendix E, Tables E-14 through E-17.
7-8
-------
Recent and Planned Remedial Activities--
The practice of washing residual spilled ore into the waterway has been
curtailed. Spilled ore is currently collected in a sweeper truck. The re-
claimed material is transferred into drums for sale to smelters (Carter, S.,
25 September 1987, personal communication). The use of a closed conveyor
and a transfer bucket equipped with a special seal was also instituted
recently. The seal apparently reduces alumina spillage significantly. The
Terminal 7 facility has also instituted an ongoing monitoring program to
ensure that spilled ore is cleaned from the dock area (Morrison, S.,
22 January 1988, personal communication).
7.2.2 Storm Drains
Sixteen storm drains discharge directly into Sitcum Waterway
(Figure 7-4). Eight serve the Port of Tacoma's Terminal 7 property (SI-167,
SI-168, SI-169, SI-170, SI-171, SI-717, SI-719, and SI-824), two serve the
office area at the head of the waterway (SI-716-01 and SI-716-02), and three
serve the Sea-Land container terminal (SI-176, SI-718-01, and SI-718-02).
Three other storm drains entering the head of Sitcum Waterway (SI-733,
SI-175, and SI-172) drain the commercial and industrial areas on the south
side of llth Street. SI-172 is the largest storm drain in Sitcum Waterway,
serving approximately 170 ac (40 percent of the total area draining to the
waterway).
Drainage areas and estimated annual stormwater discharges from the
drains in Sitcum Waterway are summarized in Table 7-2. Runoff estimates are
based on an average annual precipitation of 37 in (Norton and Johnson 1985a)
and on runoff coefficients determined for each drainage basin. The Sea-Land
and Port of Tacoma properties located north of llth Street are almost
entirely covered with impermeable surfaces (e.g., pavement and buildings).
A runoff coefficient of 0.95 was used to calculate the annual stormwater
discharges from drains serving these areas (Viessman et al. 1977). The area
south of llth Street is a combination of paved industrial properties and
unpaved, undeveloped areas. Runoff coefficients used for the three storm
drains serving this area, SI-733, SI-175, and SI-172, were 0.4, 0.4, and 0.6,
respectively.
Several industries also discharge noncontact cooling or process
wastewater to the Sitcum Waterway storm sewer system. NPDES permit-holders
for such discharges include Georgia Pacific Resins (No. 21 in Figure 7-1),
Pabco Roofing Products (formerly Certain-Teed Products Corporation, No. 22
in Figure 7-1), Purex Corporation (No. 18 in Figure 7-1), and Allied
Chemical Corporation (No. 25 in Figure 7-1).
Storm Drain SI-172--
Data collected during a single storm event indicate that SI-172 is the
largest source of storm drain metals loading to Sitcum Waterway. Norton and
Johnson (1985b) found that discharge from SI-172 accounted for about
80 percent of the flow (8 ft3/sec) into the waterway on the day of the storm
and sampling event (26 June 1984). Extrapolating these data to a daily
7-9
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^BvwrEHWAV
-------
TABLE 7-2. STORM DRAINS DISCHARGING
INTO SITCUM WATERWAY
Drain
SI-719
SI-167
SI-168
SI -824
SI-169
SI-717
SI-170
SI-171
SI-172
SI-716-01
SI-716-02
SI-175
SI-733
SI-176
SI-718-01
SI-718-02
Basin Area
(ac)
5
7
30
15
30
Unknown
Unknown
Unknown
170
Unknown
Unknown
30
60
40
Unknown
Unknown
Estimated Annual
Stormwater Runoff
(ac-ft/yr)
15
20
90
40
90
--
--
--
300
--
--
40
80
120
—
--
7-11
-------
loading rate during this event suggests that SI-172 accounted for
80-90 percent of the copper (7.6 Ib/day), lead (8.6 Ib/day), and zinc load
(24 Ib/day), and for 98 percent of the arsenic load (5.1 Ib/day) to Sitcum
Waterway. This finding is based on samples collected from 10 storm drains
(SI-172, SI-716-02, SI-716-01, SI-175, SI-176, SI-718-02, SI-718-01, SI-719,
SI-167, and SI-717) on 26 June 1984. Although metals concentrations in
several of the other nine storm drains sampled on 26 June 1984 (e.g., SI-176,
SI-719, SI-717, and SI-718-02) were similar to those measured in SI-172, the
total loading was small because there was little flow in these drains.
Class I inspections are scheduled for the spring of 1988 for most of the
businesses contributing to SI-172 (Morrison, S., 22 January 1988, personal
communication).
The City of Tacoma Sewer Utilities Department began an effluent testing
program in October 1986. Storm drain SI-172, three drains in City Waterway,
and one drain in Wheeler-Osgood Waterway are included in the program.
Available data (Getchell, C., 12 October 1987, 18 December 1987, and
8 February 1988, personal communication) indicate that particulate matter in
this storm drain is contaminated. Metals concentrations in particulate
matter from drain SI-172 consistently exceeded sediment cleanup goals for
copper, lead, and zinc. In two of the four sampling periods for which dry
weather data are available, the arsenic cleanup goal was also exceeded.
.Comparison of storm drain sediment quality with remedial action cleanup
goals provides a worst-case analysis: mixing with cleaner sediments from
other sources is not considered.
Dames & Moore (1982) identified the following potential historical
sources of contaminants in the SI-172 drainage basin:
• Rheen Manufacturing Company, located at 1702 Port of Tacoma
Road, was reported as having possibly discharged paint wastes
to the SI-172 drainage system for a period of approximately
10 yr prior to 1982
• Woodlam, Inc., manufacturer of laminated products located at
1476 Thorne Road, was reported to have discharged phenol glues
out the back door of this facility.
Other Storm Drains--
Sediments collected recently by Ecology (Norton, D., 15 April 1988,
personal communication) from storm drains SI-168, SI-169, and SI-733 were
analyzed for priority pollutants. Arsenic, copper, lead, and zinc
concentrations in sediments from drains SI-168 and SI-169 were greater than
the long-term cleanup goals for these constituents. Lead and zinc concentra-
tions in sediments from drain SI-733 also exceeded the cleanup goals.
The Milwaukee Railroad yards located in the SI-175 and SI-176 drainage
basins are also potential historical contaminant sources. Milwaukee
Railroad operated lines along Milwaukee Way on both the north and south
sides of E. llth Street. During the late 1950s, unspecified residual
materials from railroad cars were dumped on the ground in the railroad yard
7-12
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on the south side of E. llth Street and have accumulated on surficial soils
(Dames & Moore 1982). Although Dames & Moore (1982) report that surface
water runoff from the area entered Milwaukee Waterway, the Tacoma Pierce
County Health Department (1983) drainage map indicates that surface water
runoff from this area discharges into Sitcum Waterway via SI-175 or the
newly installed (1984) SI-733. Numerous spills have also occurred in this
area. Spills were generally not cleaned up and materials were allowed to
seep into the ground (Dames & Moore 1982).
Numerous solid and liquid spills occurred at the Milwaukee Railroad
yard located on the north side of E. llth Street along the west bank of
Sitcum Waterway (Dames & Moore 1982). Contaminants present in the spilled
materials accumulated in the surficial soils and may have been transported
to the waterway in stormwater runoff. This area is currently leased from
the Port of Tacoma by Sea-Land for use as a container terminal. Because the
area is completely paved, it is probably not an ongoing source of stormwater
contamination. However, it may contribute contaminants to Sitcum Waterway
via tidal flushing of contaminated groundwater. In addition, ASARCO slag
was used as riprap along the west bank of Sitcum Waterway in the area.
Loading Summary--
Summary loading tables for the Priority 2 contaminants of concern for
Sitcum Waterway (i.e., arsenic, copper, lead, and zinc) are provided in
Appendix E exclusive of data from the City of Tacoma storm drain monitoring
program. For the contaminants of concern, measured loadings (nine observa-
tions) range over 2 orders of magnitude. Additional data, not reported in
the loading tables, from two dry-weather sampling events are also wide-
ranging. Loading estimates based on these latter data sets are as follows:
undetected and 0.2 Ib/day for arsenic, 2.63 and 10.2 Ib/day for copper, 0.2
and 4.9 Ib/day for lead, and 4.7 and 33 Ib/day for zinc (Odell, C.,
20 April 1988, personal communication). With the possible exception of
SI-176 for arsenic and SI-172 for arsenic, copper, and zinc, average
inorganic contaminant concentrations derived from limited storm drain
discharge data for the waterway are similar to those derived from the
National Urban Runoff Program by Schueler (1987) and to those from Metro
(Stuart et al. 1988).
7.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the effects of source control and natural
recovery processes were evaluated. This evaluation was based on the levels
of contamination in sediment and assumptions regarding the relationship
between sources and sediment contamination. Included within the evaluation
was an estimate of the degree of source control needed to maintain acceptable
levels of sediment contaminants over the long term.
7-13
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7.3.1 Feasibility of Source Control
The two main sources of metals discharge are ore spillage (at the Port
of Tacoma Terminal 7 ore unloading facility) and surface water runoff (from
16 storm drains that convey storm water directly into Sitcum Waterway).
Terminal 7 Ore Unloading Facilities—
The Port of Tacoma ore unloading facilities (including storm drains
SI-168 and SI-169) have been associated with elevated concentrations of
inorganic contaminants in adjacent sediments. Ore spillage and discharge of
contaminants entrained in stormwater runoff are suspected as two of the
primary ongoing or historical sources of metals to the waterway.
Three best management practices have already been implemented at the
facility: collection of spilled ore via a sweeper truck, implementation of
a monitoring program to ensure that spilled ore is removed from the dock
area, and use of a bucket equipped with special seals and a closed conveyer.
Given the types of contaminants, source pathways, and available control
technologies, it is estimated that implementation of all known, available,
and reasonable (i.e., feasible) technologies will reduce source inputs by
80 percent.
Storm Drains--
Storm drain SI-172 has been identified as the biggest contributor of
metals to Sitcum Waterway via storm drains (Tetra Tech 1985a). The City of
Tacoma is presently testing effluent from the drain under its storm drain
monitoring program. Several of the storm drains discharging into Sitcum
Waterway (particularly SI-168 and SI-169) have also been identified as
sources of metals.
Available technologies for controlling surface water runoff to storm
drains are summarized in Section 3.2.2. These technologies include methods
for retaining runoff onsite (e.g., berms, channels, grading, sumps),
revegetation or capping of waste materials, and waste removal or treatment.
Treatment methods for stormwater after collection in a drainage system
also exist. Sedimentation basins and vegetation channels (or grassy swales)
have been shown to remove contamination associated with particulate matter.
Removals of up to 75 percent for total suspended solids and 99 percent for
lead have been reported for detention basins (Finnemore and Lynard 1982;
Homer and Wonacott 1985). Removals of 90 percent for lead, copper, and
zinc and 80 percent for total suspended solids have been achieved using
grassy swales (Horner and Wonacott 1985; Miller 1987).
Given the contaminant types, multiplicity of sources, and available
control technologies, it is estimated that implementation of all known,
available, and reasonable technologies will reduce contaminant inputs from
storm water by up to 80 percent.
7-14
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Conclusion--
For the waterway, the estimated maximum feasible level of source
control for the two indicator chemicals is assumed to be 80 percent for
copper and 80 percent for arsenic. These estimates reflect both the assumed
effectiveness of implementing best management practices for the Terminal 7
ore handling operations as well as uncertainty regarding the relative
importance of storm drain inputs and source control technologies. More
precise source control estimates require improved definition of the sources
of copper and arsenic, which is beyond the scope of this document.
7.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals copper and arsenic. Results are
reported in full in Tetra Tech (1987a). A summary of those results is
presented here.
The depositional variables in Sitcum Waterway were estimated from
measurements taken in adjacent waterways. A sedimentation rate of
2,400 mg/cm2/yr (1.65 cm/yr) and a mixing depth of 10 cm were selected for
modeling sedimentation in Sitcum Waterway. Two indicator chemicals (copper
and arsenic) were used to evaluate the effect of source control and the
degree of source control required for sediment recovery. Losses due to
biodegradation and diffusion were determined to be negligible for these
indicator chemicals. Source loadings of both indicator chemicals in Sitcum
Waterway were assumed to be in steady-state with sediment accumulation. This
assumption is environmentally protective in that sediment profiles suggest a
recent decrease in inorganic contaminant loading (Tetra Tech 1987a). Two
timeframes for sediment recovery were considered: a reasonable timeframe
(defined as 10 yr) and the long term. Results of the sediment recovery
evaluation are summarized in Table 7-3.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times are predicted to
be 17 yr for copper and 13 yr for arsenic. Therefore, sediment recovery in
the 10-yr timeframe is not predicted to be possible under conditions of
complete source elimination for either copper or arsenic. These predictions
are based on the highest concentrations of the indicator chemicals measured
in the problem area. Minimal reductions in sediment concentrations are
predicted unless sources are controlled.
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source control
is expected to reduce source inputs by 80 percent for both arsenic and
copper. With this level of source control as an input value, the model
predicts that sediments with an enrichment ratio of 2.9 (i.e., copper
7-15
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TABLE 7-3. SITCUM WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
Copper Arsenic
Station with Highest Concentration
Station identification 3a SI-04
Concentration (mg/kg dry weight) 2,100 472
Enrichment ratio'' 5.4 8.3
Recovery time if sources are
eliminated (yr) 17 13
Percent source control required
to achieve 10-yr recovery NPC NPC
Percent source control required
to achieve long-term recovery 79 88
Average of Three Highest Stations
Concentration (mg/kg dry weight) 1,490 400
Enrichment ratiob 3.8 7.0
Percent source control required
to achieve long-term recovery 70 86
IQ-Yr Recovery
Percent source control assumed
feasible 80 80
Highest concentration recovering
in 10 yr (mg/kg dry weight) 1,131 165
Highest enrichment ratio of sediment
recovering in 10 yr 2.9 2.9
a On the basis of more recent information observed at nearby stations, the
enrichment ratio of 23 observed at Station 1-9 in 1981 is not believed to
be representative of current conditions.
b Enrichment ratio is the ratio of observed concentration to target cleanup
goal.
c NP = Not possible.
7-16
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concentrations of 1,131 mg/kg dry weight, arsenic concentration of 165 mg/kg
dry weight) will recover to the long-term cleanup goal within 10 yr (see
Table 7-3). The surface area of sediments not recovering to the cleanup goal
within 10 yr is shown in Figure 7-5. For comparison, sediments currently
exceeding long-term cleanup goals for the indicator chemicals are also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that 70 percent of the copper and 86 percent of the
arsenic inputs must be eliminated to maintain acceptable contaminant
concentrations in freshly deposited sediments (see Table 7-3). These
estimates are based on the average of the three highest enrichment ratios.
These values are presented for comparative purposes; the actual percent
reduction required in source loading is subject to the uncertainty inherent
in the assumptions of the predictive model. These ranges probably represent
upper limit estimates of source control requirements since the assumptions
incorporated into the model are considered to be environmentally protective.
For comparison with source control estimates derived by using the
mathematical model, the percent reductions necessary to meet long-term
cleanup goals were calculated for particulate matter from SI-172. Based on
six measurements by the City of Tacoma (Getchell, C., 12 October 1987,
18 December 1987, 8 February 1988, and 19 August 1988, personal communica-
tions), average reductions of 67 percent for arsenic and 73 percent for
copper would be needed to achieve sediment cleanup goals in particulate
matter from storm drain SI-172 effluent. Based on one measurement of
sediments (Norton, D., 15 April 1988, personal communication), reduction of
54 percent would be required to achieve the arsenic cleanup goal and
reduction of 96 percent would be required to achieve the copper cleanup goal
in both storm drains SI-168 and SI-169. As a measure of relative priority
for source control, drain SI-172 supplies 38 percent of the estimated annual
stormwater runoff flow to Sitcum Waterway, while SI-168 and SI-169 each
supply approximately 11 percent (see Table 7-2).
7.3.3 Source Control Summary
The major sources of metals to Sitcum Waterway are the Port of Tacoma
Terminal 7 ore unloading facilities and several area storm drains. If these
sources are completely eliminated, it is predicted that sediment concentra-
tions in the surface mixed layer of the indicator chemical copper will
decline to the long-term cleanup goal of 390 mg/kg in 17 yr and that those of
arsenic will decline to the long-term cleanup goal of 57 mg/kg in 13 yr.
Sediment remedial action will therefore be required to mitigate the observed
and potential adverse biological effects associated with sediment contamina-
tion.
Substantial levels of source control will also be required to maintain
acceptable sediment concentrations of the indicator chemicals even with
sediment cleanup. The estimated percent reduction required for long-term
maintenance is 70 for copper and 86 for arsenic.
7-17
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IN10YR
00
Sltcum Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA(yd2)
VOLUME (yd3)
IN 10 YR
DEPTH (yd)
AREA (yd 2)
VOLUME (yd3)
1
167,000
167,000
1
66,000
66.000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
ARSENIC (AET = 57 mg/kg)
COPPER (AET = 390 mg/kg)
BIOLOGICAL EFFECTS OBSERVED
FOR NON-INDICATOR COMPOUNDS
Figure 7-5. Sediments in Sitcum Waterway not meeting cleanup goals for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
The implementation of all known available and reasonable control
technologies is expected to provide approximately a 80 percent reduction in
contaminant loading to the waterway. This level of source control appears
feasible for maintaining the cleanup goal for copper. The 6 percent
difference between the percent source control assumed feasible for arsenic
(80 percent), and the percent source control required to achieve long-term
recovery for arsenic (86 percent) may be insignificant given the uncertain-
ties in estimates of feasible source control and conservative assumptions
built into the model. If implementation of all known, available, and
reasonable control technologies fails to achieve the necessary level of
source control required to maintain sediment quality, then re-evaluation of
the area requiring remediation based on arsenic concentrations may be
required.
7.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with copper or arsenic concen-
trations exceeding long-term cleanup goals is approximately 167,000 yd3 (see
Figure 7-5). This volume was estimated by multiplying the areal extent of
sediment exceeding the cleanup goal (167,000 yd2) by the estimated 1-yd
depth of contamination (see contaminant sediment profiles in Figures 7-2 and
7-3. The estimated thickness of contamination is only an approximation; few
sediment profiles were collected and the vertical resolution of these
profiles was poor at the depth of the contaminated horizon. For the volume
calculations, depths were slightly overestimated. This conservative
approach was taken to account for dredge technique tolerances and to account
for uncertainties in sediment quality at locations between the sediment
profile sampling stations.
The total estimated volume of sediments with copper or arsenic concen-
trations that is still expected to exceed long-term cleanup goals 10 yr
following implementation of feasible levels of source control is 66,000 yd3.
This volume was estimated by multiplying the areal extent of sediment
contamination with enrichment ratios greater than 2.9 (see Table 7-3), an
area of 66,000 yds by the estimated 1-yd depth of contamination. These
volumes are also approximations, accounting for uncertainties in sediment
profile resolution and dredging tolerances.
In addition to chemical concentrations that exceed long-term cleanup
goals for indicator chemicals, biological effects were observed at one
station (SI-12; see Appendix F) as a result of elevated concentrations of the
nonindicator compounds (see Figure 7-5)- The volume of sediment exceeding
long-term cleanup goals for these compounds is estimated as 10,000 yd3.
Sediment concentrations in these sediments are expected to recover to
acceptable levels within approximately 10 yr.
The quantity of sediment used in evaluating the remedial alternatives
(i.e., to identify the preferred alternative) was determined by adding the
following values:
• The volume of all sediments currently exceeding the long-term
cleanup goal within the waterway (i.e., 157,000 yd3)
7-19
-------
• The volume of sediment in the vicinity of the station where
biological effects were observed for nonindicator compounds
(approximately 10,000 yd3)-
For Sitcum Waterway, the volume of sediment requiring remediation is
therefore 167,000 yd"3.
7.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
7.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion, each alternative is evaluated to
determine its suitability for the remediation of contaminated sediments in
Sitcum Waterway. The objective of this evaluation is to identify the
alternative considered preferable to all others based on CERCLA/SARA
criteria of effectiveness, implementability, and cost.
The first step in this process is to assess the applicability of each
alternative in the waterway. Site-specific characteristics that must be
considered include the nature and extent of contamination, the environmental
setting, and site physical properties such as waterway usage, bathymetry,
and water flow conditions. Alternatives that are determined to be appro-
priate for the waterway can then be evaluated based on the criteria discussed
in Chapter 4.
The indicator chemicals arsenic and copper were selected to represent
the two primary sources of contamination to the waterway: storm drains and
the Terminal 7 ore unloading facilities (see Table 7-1). Areal distributions
for both indicators are presented in Figure 7-5 to indicate the degree to
which contaminant groups overlap based on long-term cleanup goals and
estimated 10-yr sediment recovery. The U.S. Army Corps of Engineers is
required to maintain water depths in Sitcum Waterway for shipping. For the
first 1,000 ft of waterway extending from the head towards the mouth, the
required channel depth is 35 ft below MLLW. For the remaining length of the
waterway, the minimum channel depth is 40 ft below MLLW. The channel width
along the entire length of the waterway is 300 ft.
Four alternatives are dropped from consideration for Sitcum Waterway.
The need for periodic dredging to maintain channel depth precludes placement
of a cap on existing sediments within channel boundaries. The bottom
surfaces along sloping embankments outside the channel lines and adjacent to
the channel where maintenance dredging will occur are also inappropriate for
capping technologies where long-term isolation of sediments must be ensured.
Therefore, the in situ capping alternative is dropped from further consider-
ation in Sitcum Waterway. Alternatives involving treatment of organic
contaminants are inappropriate because the sediments are contaminated with
predominantly inorganic contaminants. Therefore, the solvent extraction,
incineration, and land treatment alternatives are also dropped from further
consideration.
7-20
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The remaining six candidate sediment remedial alternatives for Sitcum
Waterway are listed below:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic disposal
• Hydraulic dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solidification/upland disposal.
These candidate alternatives are described in detail in Chapter 3.
Because of the close proximity of the problem area to the proposed nearshore
disposal site in Blair Waterway, the dredging and nearshore disposal option
has been defined to include a hydraulic dredging system for sediment removal,
transport, and disposal.
Evaluation of the no-action alternative is required by the NCR to
provide a baseline against which other remedial alternatives can be
compared. The institutional controls alternative, which is intended to
protect the public from exposure to contaminated sediments without imple-
menting sediment mitigation, provides a second baseline for comparison. The
three nontreatment dredging and disposal alternatives are applicable to
remediation of sediment contamination in Sitcum Waterway. Solidification is
retained as an appropriate treatment technology because it is primarily used
to treat materials contaminated with inorganics. This treatment technology
may also be effective in immobilizing the Priority 3 organic contaminants,
which are assumed to have a high particle affinity.
7.5.2 Evaluation of Candidate Alternatives
The three primary categories of evaluation criteria are effectiveness,
implementability, and cost. A narrative matrix summarizing the assessment
of each alternative based on effectiveness and implementability is presented
in Table 7-4. A comparative evaluation of alternatives is presented in
Table 7-5, based on ratings of high, moderate, and low in seven subcategories
of evaluation criteria. As discussed in Chapter 4, the effectiveness
subcategories are short-term protectiveness; timeliness; long-term protec-
tiveness; and reduction in toxicity, mobility, or volume. The implement-
ability subcategories are technical feasibility, institutional feasibility,
and availability. Capital and O&M costs for each alternative are also
presented in Table 7-5.
Short-Term Protectiveness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
7-21
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EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
I/ENESS
ERM PROTECT!1
H
6
Z
o
[CONTAMINANT
MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION *
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 7-4. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE SITCUM WATERWAY PROBLEM AREA
NO ACTION
NA
NA
Original contamination remains.
Source inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative Is ranked
sixth overall for timeliness.
COM containment is not an
aspect of tfiis alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxicity and contam-
inant mobtlty are expected to
remain at current levels or
increase as a result of continued
source inputs. Contaminated
sediment volume increases as
a result of continued source
Inputs.
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
Source control is implemented
and would reduce sediment con-
tamination with time, but adverse
impacts would persist in the in-
terim.
Access restrictions and monitor-
ing efforts can be implemented
quickly. Partial sediment re-
covery is achieved naturally, but
significant contaminant levels
persist. Natural recovery time
ranges from 1 0 to 1 2 yrs. This
alternative is ranked fifth overall
for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a .
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity Is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Removal with dredge
and disposal with downplpe and
diffuser minimizes handling re-
quirements. Workers wear pro-
tective gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment is resuspended during
dredging operations. Benthic
habitat is impacted at the dis-
posal site. Habitat has a lower
sensitivity level than nearshore.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
Disposal siting and facility con-
struction could delay imple-
mentation. This alternative is
ranked second overall for time-
liness.
Trie long-term reliability of the
cap to prevent contaminant re-
exposure in a quiescent, sub-
aquatic environment is consid-
ered acceptable.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota.' Protection is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment.
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in
situ conditions. _
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
HYDRAULIC DREDGE/
NEARSHORE DISPOSAL
Hydraulic dredging confines
COM u> a pipeline during trans-
port. Public access to dredge
and disposal sites is restricted.
Public exposure potential is low.
Hydraulic dredging confines
COM to a pipeline during trans-
port Dredge water contamina-
tion may Increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed. Nearshore inter-
tidal habitat is lost. Contami-
nated sediment is resuspended.
Dredge water can be managed
to prevent release of soluble
contaminants.
Dredge and disposal operations
could be accomplished quickly.
This alternative can be imple-
mented rapidly with available
technologies and expertise.
Disposal site identified. This
alternative is ranked first for
timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM.
Varying physicochemical con-
ditions in the fill may increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment. The
potential for contaminant migra-
tion into marine environment may
increase over CAD. Adjacent
fish mitigation site is sensitive
area.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. Altered
conditions resulting from hy-
draulic dredge operations may
increase mobility of metals.
Volume of contaminated sedi-
ments is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM is confined to a pipeline
during transport Public access
to dredge and disposal sites Is
restricted. Exposure from COM
spills or mishandling is possible,
but overall potential is low.
Hydraulic dredging confines
COM ID a pipeline during trans-
port. Dredge water contamina-
tion may Increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment Is resuspended during
dredging operations. Dredge
water can be managed to pre-
vent release of soluble contami-
nants. Habitat has a lower sen-
sitivity level than nearshore.
Dredge and disposal operations
could be accomplished within
approximately 1 to 2 years.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked third
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM. Al-
though the potential for ground-
water contamination exists, it is
minimal. Upland disposal facili-
ties are more secure than near-
shore facilities.
Upland disposal is secure, with
negligible potential for environ-
mental impact if properly de-
signed. Potential for ground-
water contamination exists.
The toxicity of COM in the con-
finement zone remains at prere-
mediation levels. The potential
for migration of metals is greater
for upland disposal than for CAD
or nearshore disposal. Volume
of contaminated sediments Is
not reduced and may Increase
with hydraulic dredge operations.
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Public access to dredge treat-
ment and disposal sites is re-
stricted. Exposure from COM
spills or mishandling is possible,
but overall potential is tow.
Additional CDM handling asso-
ciated with treatment increases
worker risk over dredge/disposal
options. Workers wear protec-
tive gear. Increased potential
for worker exposure due to
direct handling of COM.
Existing contaminated habitat
Is destroyed. Contaminated
sediment is resuspended during
dredging operations.
Substantial CDM testing and
equipment development are
required before a solidification
scheme can be implemented.
This alternative is ranked fourth
overall for timeliness.
Long-term reliability of solidifica-
tion treatment processes for
CDM are believed to be ade-
quate. However, data from
which to confirm long-term relia-
bility are limited. Upland dis-
posal facilities are structurally
reliable.
Solidification is a more protec-
tive solution than dredge/dis-
posal alternatives. The poten-
tial for public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Solidification Is a more protec-
tive solution than dredge/dis-
posal alternatives. The poten-
tial for public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Contaminants are physically
contained, thereby reducing
toxicity and the potential for
contaminant migration com-
pared with non-treatment alter-
natives. Metals and organics
are encapsulated.
7-22
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| IMPLEMENTABILITY |
TECHNICAL FEASIBILITY
INSTITUTIONAL FEASIBILTY
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION,
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIfcS
COMPLIANCE
WITH ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 7-4. (CONTINUED)
NO ACTION
Implementation of mis alterna-
tive Is feasible and reliable.
No monitoring over and above
programs established under
other authorities Is Implemented.
There are no O 4 M requirements
associated with the no action
alternative.
This alternative is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the intent of CERCUV
SARA and NCP because of on-
going impacts.
All materials and procedures are
available.
INSTITUTIONAL
CONTROLS
Source control and Institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily implemented.
Adequate coverage of problem
area would require an extensive
program.
O A M requirements are minimal.
Some O A M Is associated with
monitoring, maintenance of
warning signs, and Issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels in sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
Impacts. State requirements
for source control are achieved.
Coordination with TPCHD for
health advisories for seafood
consumption is required.
All materials and procedures are
available to implement institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment
Is reliable. Placement of dredge
and capping materials difficult,
although feasible. Inherent diffi-
culty in placing dredge and cap-
ping materials at depths of 100 ft
or greater.
Confinement reduces monitoring
requirements in comparison to
institutional controls. Sediment
monitoring schemes can be
readily implemented.
O & M requirements are minimal.
Some O & M Is associated with
monitoring for contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desirable
than if COM Is treated.
WISHA/OSHA worker protection
is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Waterway CAD site
is considered available. Availa-
bility of open water CAD sites is
uncertain.
HYDRAULIC DREDGE/
NEARSHORE DISPOSAL
Hydraulic dredging equipment
is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Instal-
lation of monitoring systems is
routine aspect of facility siting.
O & M requirements consist of
inspections, groundsKeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for faci-
lity siting is uncertain but is as-
sumed feasible. However, dis-
posal of untreated COM is con-
sidered less desirable than if
COM is treated.
WISHA/OSHA worker protection
required. Alternative complies
with U.S. EPA's onsite disposal
policy. Substantive aspects of
CWA, hydraulics, and shoreline
management programs must be
addressed. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been identified
and Is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
is reliable. Secure upland con-
finement technology is well de-
veloped.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes and
liners. Improved confinement
enhances monitoring over CAD.
Installation of monitoring sys-
tems is routine aspect of facility
siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Coordination is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Alternative complies
with U.S. EPA's onsite disposal
policy. Substantive aspects of
CWA, hydraulics, and shoreline
management programs must be
addressed. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Solidification technologies (or
treating COM on a large scale
are conceptual. Implementation
is considered feasible, but reli-
ability is unknown. Bench-scale
testing prior to implementation is
necessary.
Monitoring requirements for so-
lidified material are low in com-
parison with dredge and dispos-
al alternatives. Monitoring can
be readily implemented.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment. System mainten-
ance is intensive during Imple-
mentation.
Disposal requirements are less
stnngent for treated dredge ma-
terial, enhancing approval feasi-
bility. However, bench scale
testing is required to demon-
strate effectiveness of solidifi-
cation.
WISHA/OSHA worker protection
required. Alternative complies
with U.S. EPA's policies for on-
site disposal and permanent re-
duction in contaminant mobility.
May require that substantive
aspects of CWA and shoreline
management programs be ad-
dressed.
Disposal site availability is un-
certain but feasible. Solidifica-
tion equipment and methods for
large-scale COM disposal are
currently unavailable.
7-23
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TABLE 7-5. EVALUATION SUMMARY FOR SITCUM WATERWAY
Short-Term Protectiveness
Timeliness
Long-Term Protectiveness
Reduction in Toxicity,
Mobility, or Volume
Technical Feasibility
Institutional Feasibility
"-« Availability
rsj
•f* Long-Term Cleanup
Goal Cost3
Capital
0 6 M
Total
Long-Term Cleanup
Goal with 10-yr
Recovery Cost3-"
Capital
0 & M
Total
No Action
Low
Low
Low
Low
High
Low
High
—
—
—
—
—
— —
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
1,989
1,995
6
865
871
Cl amshel 1 /
CAD
High
Moderate
High
Low
Moderate
Moderate
Moderate
1,327
309
1,636
544
125
669
Hydraulic/
Nearshore
Di sposal
Moderate
High
Moderate
Low
High
Moderate
High
4,073
343
4,416
1,612
139
1.751
Hydraulic/
Upland
Disposal
High
Moderate
Moderate
Low
High
Moderate
Moderate
7,301
459
7,760
2,887
185
3,072
Cl amshel 1 /
Solidify/
Upland
Di sposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
11,084
443
11,527
4,400
178
4,578
a All costs are in $1,000.
** Includes sediment for which biological effects were obseved for non-indicator compounds.
-------
biological and potential public health impacts would continue as the
contaminated sediments remained in place. Source control measures initiated
as part of the institutional controls would result in reduced sediment
contamination with time, but adverse effects would persist in the interim.
The alternative requiring hydraulic dredging/nearshore disposal is
rated moderate under this criterion because nearshore habitat would be lost
in developing the disposal facility. The clamshell dredging/solidifi-
cation/upland disposal alternative is also rated moderate because of the
increased potential for worker exposures due to direct contact during
solidification-related handling of contaminated dredged material. The
potential hazard due to exposure during the treatment process is not
expected to be major because of the nature and concentration of contaminants.
In spite of the increased exposure potential, the moderate rating is
appropriate because adequate worker health and safety controls are available.
The confined aquatic disposal and hydraulic dredging/upland disposal
alternatives are rated high for short-term protectiveness because worker and
public exposure potentials are minimized, and because the habitats that are
compromised for disposal are of lower sensitivity than nearshore habitats.
The confinement of contaminated dredged material in the subaquatic environ-
ment at a designated disposal site outside the waterway, using a mechanical
dredge for removal and a split-hulled barge for disposal, minimizes handling
requirements. Hydraulic dredging with upland disposal confines contaminated
dredged material to a pipeline system throughout implementation, thereby
reducing exposure potentials.
For the solidification alternative, if contaminated dredged material is
determined to be unacceptable for disposal at an existing solid waste
landfill, use of a previously unaffected site may be required. Although
this would result in short-term impacts in the upland environment, the
tradeoff of improved waterway habitat and marine productivity may offset the
impacts of placing inorganic contaminants in an upland environment at
concentrations that may not pose a significant environmental threat at the
disposal site.
Timeliness--
Because an extensive amount of time is necessary for sediments to
recover naturally, both the no-action and institutional controls alter-
natives are rated low. Natural recovery times for the two indicator
compounds range from 13 to 17 yr (see Section 7.3).
Moderate ratings have been applied to the clamshell dredging/confined
aquatic disposal, hydraulic dredging/upland disposal, and clamshell
dredging/solidification/upland disposal options. For dredging options that
involve siting of unused and undeveloped upland or confined aquatic disposal
facilities, approvals and construction are estimated to require 1-2 yr.
Solidification may require additional time for bench-scale testing, equipment
development, or modification and actual treatment of sediments. However,
facility siting and technology development could be conducted concurrently.
Once approval is obtained, treatment of contaminated sediments using
7-25
-------
solidification to target goals would require a period of approximately
1-2 yr, assuming a maximum treatment rate of 1,000 yd3/day.
The hydraulic dredging/nearshore disposal option is rated high for
timeliness because this alternative can be implemented rapidly with available
technologies and expertise. Major site development would be required (e.g.,
diking) but can be completed in a relatively short timeframe.
Long-Term Protectiveness--
The comparative evaluations for long-term protectiveness resulted in
low ratings for the no-action and institutional controls alternatives
because the timeframe for natural recovery is long. For the institutional
controls alternative, the potential for exposure to contaminated sediments
remains, albeit at declining levels following implementation of source
reductions, and the observed adverse biological impacts continue.
Moderate ratings are assigned for hydraulic dredging/nearshore disposal
and hydraulic dredging/upland disposal alternatives because of potential
physicochemical changes due to placing contaminated dredged material in these
disposal facilities. These chanqes, primarily from new conditions affecting
reduction and oxidation (redox) reactions, would tend to increase the
migration potential of the contaminants. Contaminated dredged material
testing should provide the necessary data on the magnitude of these impacts.
In a nearshore site, physicochemical changes could be minimized by placing
sediments below the low tide water elevation. Although the structural
reliability of the nearshore facilities is regarded as good, the nearshore
environment is dynamic in nature as a result of wave action and tidal
influences. In addition, the fish mitigation area in the outer Blair
Waterway slip adjacent to the proposed disposal facility is regarded as a
sensitive area. The upland disposal facility would be generally regarded as
a more secure option because of improved engineering controls during
construction, but the potential for impacts on area groundwater resources
partially offsets the improvement in long-term security.
Both the clamshell dredging/confined aquatic disposal and the clamshell
dredging/solidification/upland disposal alternatives are rated high for long-
term protectiveness. Placement of material in a confined, quiescent,
subaquatic environment provides a high degree of isolation, with little
potential for exposure to an environment sensitive to the contaminated
dredged material. In addition, confinement under these circumstances
maintains physicochemical conditions comparable to in situ conditions,
further reducing contaminant migration potential. The high degree of
immobilization provided by solidification of primarily inorganic contaminants
substantially increases the long-term protectiveness of this alternative
over dredge and disposal alternatives.
Reductions in Toxicity, Mobility, or Volume--
Low ratings have been assigned to all alternatives under this criterion,
except the clamshell dredging/solidification/upland disposal option which
was rated high. None of the other five alternatives involves treatment of
7-26
-------
contaminated sediments. Although the confined aquatic, upland, and nearshore
disposal alternatives isolate contaminated dredged material from the
surrounding environment, the chemistry of the material remains unaltered.
For nearshore and upland disposal alternatives, the mobilization potential
for untreated contaminated dredged material may actually increase with
changes in redox potentials. Without treatment, the toxicity of contaminated
sediments remains at preremediation levels. Contaminated sediment volumes
are not reduced, and may actually increase with hydraulic dredging options
because of suspension of the material in an aqueous slurry.
Solidification of contaminated dredged material prior to disposal
effectively encapsulates inorganic contaminants, thereby reducing mobiliza-
tion potential permanently and significantly. Through isolation in the
solidified matrix, this process also reduces the effective toxicity of
contaminants as compared with nontreatment alternatives. Because the
available data suggest that the organic contaminants present have a high
particle affinity, the process may also be relatively effective in encap-
sulating these compounds. Elutriate tests during bench-scale testing of
solidified contaminated dredged material will provide sufficient data to
substantiate or invalidate these conclusions.
Technical Feasibility--
Clamshell dredging/solidification/upland disposal has been assigned a
moderate rating for technical feasibility because of the need to conduct
bench-scale testing prior to implementation. Solidification technologies
for the treatment of contaminated dredged material on a large scale are
conceptual at this point, although the method appears to be feasible
(Cullinane, J., 18 November 1987, personal communication). A moderate
rating is also applied to the clamshell dredging/confined aquatic disposal
option. Placement of dredge and capping materials at depths of approximately
100 ft is difficult, although feasible. Considerable effort and resources
may be required to monitor the effectiveness and accuracy of dredging,
disposal, and capping operations.
High ratings have been assigned to all other alternatives because the
equipment, technologies, and expertise required for implementation have been
developed and are readily accessible. The technologies constituting these
alternati-ves have been demonstrated to be reliable and effective elsewhere
for similar operations.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods (e.g., sediment cores, monitoring wells) are
applied for all alternatives. The intensity of the monitoring effort, which
varies with uncertainty about long-term reliability, does not influence the
feasibility of implementation.
7-27
-------
Institutional Feasibility--
The no-action and institutional controls alternatives have been
assigned low ratings for institutional feasibility because compliance with
CERCLA/SARA mandates will not be achieved. Requirements for long-term
protection of public health and the environment are not met by either
alternative.
Moderate ratings have been assigned to the remaining four alternatives
because of potential difficulty in obtaining agency approvals for disposal
sites or implementation of treatment technologies.
Although several potential confined aquatic and upland disposal sites
have been identified in the project area, significant uncertainty remains
with the actual construction and development of the sites. It was assumed
that the Blair Waterway nearshore facility would be available for use.
Although excavation and disposal of untreated, contaminated sediment is
discouraged under Section 121 of SARA, properly implemented confinement
should meet requirements for public health and environmental protectiveness.
Agency approvals are assumed to be contingent upon a bench-scale demon-
stration of the effectiveness of each alternative in meeting established
performance goals (e.g., treatability of dredge water, immobilization of
contaminants through solidification).
Availability--
Candidate sediment remedial alternatives that can be implemented using
existing equipment, expertise, and disposal or treatment facilities are
rated high for availability. Because the no-action and institutional
controls alternatives can be implemented immediately, they received a high
rating. A nearshore disposal site was assumed to be available, allowing
rapid implementation of the hydraulic dredging/nearshore disposal alterna-
tive. Thus, this alternative also received a high rating for availability.
Remedial alternatives involving dredging with confined aquatic or upland
disposal are rated moderate because of the uncertainty associated with
disposal site availability. Candidate alternatives were developed by
assuming that confined aquatic and upland sites will be available. However,
no sites for contaminated sediments are currently approved for use and no
sites are currently under construction. Depending on the final characteri-
zation of sediments, upland disposal in an existing municipal or demolition
landfill may also be feasible. For costing purposes, development of a RCRA-
equivalent upland site was assumed. A moderate rating has also been
assigned to the clamshell dredging/solidification/upland disposal alternative
because of the same uncertainties regarding disposal site availability.
However, leachate tests conducted as a part of the bench-scale treatability
and performance evaluation for the solidification process should confirm that
the product is nonhazardous and suitable for a standard solid waste
management facility. For costing purposes, disposal in a standard solid
waste management facility was assumed.
7-28
-------
Cost--
Capital costs increase with increasing complexity (i.e., from no action
to the treatment option). This increase reflects the need to site and
construct disposal facilities, develop treatment technologies, and implement
alternatives requiring extensive contaminated dredged material or dredge
water handling. Costs for hydraulic dredging/upland disposal are sig-
nificantly higher than those for hydraulic dredging/nearshore disposal,
primarily due to underdrain and bottom liner installation, and use of two
pipeline boosters to facilitate contaminated dredged material transport to
the upland site. The cost of conducting the solidification alternative
increases as a result of material costs for the process, and associated
labor costs for material handling and transport. Dredge water clarification
management costs are also incurred for this option.
A major component of O&M costs is the monitoring requirements associated
with each alternative. The highest monitoring costs are associated with
alternatives involving the greatest degree of uncertainty for long-term
protectiveness (e.g., institutional controls), or where extensive monitoring
programs are required to ensure long-term performance (e.g., confined
aquatic disposal). Costs for monitoring of the confined aquatic disposal
facility are significantly higher because of the need to collect sediment
core samples at multiple stations, with each core being sectioned to provide
an appropriate degree of depth resolution to monitor migration. Nearshore
and upland disposal options, on the other hand, use monitoring well networks
requiring only the collection of a single groundwater sample from each well
to assess contaminant migration.
It is also assumed that the monitoring program will include analyses
for all contaminants of concern (i.e., those exceeding AET values) in the
waterway. This approach is conservative and could be modified to reflect
use of key chemicals to track performance. Monitoring costs associated with
the solidification alternative are significantly lower because the process
results in lower contaminant migration potential.
7.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the six candidate sediment remedial
alternatives proposed for Sitcum Waterway, hydraulic dredging with nearshore
disposal has been recommended as the preferred alternative for sediment
remediation. Because sediment remediation will be implemented according to
a performance-based ROD, the specific technologies identified in this
alternative (i.e., hydraulic dredging, nearshore disposal) may not be the
technologies eventually used to conduct the cleanup. New and possibly more
effective technologies available at the time remedial activities are
initiated may replace the alternative that is currently preferred. However,
any new technologies must meet or exceed the performance criteria (e.g.,
attainment of specific cleanup criteria) specified in the ROD. The
nearshore disposal alternative is currently preferred for the following
reasons:
7-29
-------
• The alternative protects public health and the environment by
effectively isolating contaminated sediments in an engineered
disposal facility
• The alternative is consistent with existing plans to fill the
Blair Waterway Slip 1 proposed nearshore fill site
• The nature of the contaminants is such that placement below
the saturated zone should minimize migration potential
• The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 401 and 404 of the Clean Water Act,
and other applicable environmental requirements
• Performance monitoring can be accomplished effectively and
implemented readily
• The estimated 66,000-yd^ volume of contaminated sediments is
compatible with the capacity of the proposed nearshore
facility
• The cost of this alternative is over $1 million less than
that of the upland disposal alternative, and it is expected
to provide an equivalent degree of public health and
environmental protection
• Although this option is approximately $1 million more than
the confined aquatic disposal option, largely due to the cost
of acquiring nearshore property in the project area, the
additional expenditure is justified since the action can be
implemented more quickly in an available facility that
offers appropriate confinement conditions for the contaminants
of concern.
The nearshore disposal alternative is rated high for timeliness,
technical feasibility, and availability because available equipment,
resources, and disposal facilities are used. The alternative can be
implemented quickly with reliable equipment that has proven effective in
past similar operations.
The alternative is rated moderate for short-term protectiveness because
of the loss of intertidal habitat. This disadvantage can be offset through
incorporation of a habitat replacement project in the remedial process.
This goal is addressed in part with the improvements realized by removing
contaminated sediments from the waterway itself and subsequent reestablish-
ment of that marine habitat. The alternative is rated moderate for long-
term protectiveness because contaminated sediments are placed in an
environment subject to wave and tidal influences. In addition, there is
potential for long-term impacts to the adjacent fish mitigation area in the
outer slip. However, contaminants in Sitcum Waterway have demonstrated
relatively high particle affinities (Tetra Tech 1987c), which would serve to
improve long-term containment reliability. Hart-Crowser & Associates (1985)
7-30
-------
concluded that monitoring of contaminant mobility from nearshore disposal
sites could be effectively accomplished with monitoring wells in containment
berms for early detection of contaminant movement. Long-term protectiveness
could also be improved with the placement of slurry walls within the berm
(Phillips et al. 1985); however, this measure has not been included in the
cost estimate. As indicated in Table 7-5, this alternative also provides a
cost-effective means of sediment mitigation. '
Although some sediment resuspension is inherent in dredging operations,
silt curtains and other available engineering controls would be expected to
minimize adverse impacts associated with contaminated dredged material
redistribution. The effect of dredging on water quality can be predicted by
using data from bench-scale tests to estimate contaminant partitioning to
the water column. Because this alternative can be implemented over a
relatively short timeframe, seasonal restrictions on dredging operations to
protect migrating anadromous fish are not expected to pose a problem.
Dredging activities within this area are consistent with the Tacoma Shoreline
Management Plan and Sections 404 and 401 of the Clean Water Act. Close
coordination with appropriate federal, state, and local regulatory personnel
will be required prior to undertaking remedial actions.
The confined aquatic disposal alternative was not selected because the
volume of material is compatible with the available nearshore disposal site.
The nearshore alternative can be implemented more quickly, while providing
a degree of protection that is appropriate for the contaminants of concern.
Solidification/upland disposal was not selected as the preferred
alternative since the timeframe for remedial action would be lengthened.
Implementation would require bench-scale and possibly pilot-scale testing.
In addition, treatment itself would take a considerable period of time,
given available equipment and the large volume of contaminated sediment.
Decreased mobility of contaminants due to the stabilization is not expected
to significantly increase long-term protectiveness compared with nearshore
disposal, if the sediments are maintained in a reduced environment.
Performance monitoring associated with the nearshore disposal facility would
allow early detection of movement to the surrounding environment. The nearly
$3 million greater cost for solidification/upland disposal also favors the
nearshore disposal alternative.
Hydraulic dredging with upland disposal was not selected because of
uncertain disposal site availability and the cost of siting and developing a
facility to RCRA standards for disposal of untreated contaminated dredged
material in an upland environment. The cost associated with this alternative
is approximately $1 million more than that for the nearshore disposal
alternative. Although this alternative is feasible from both a technical
and institutional standpoint, the risk of system failures in the upland
environment (e.g., groundwater risks) compromises its desirability.
No-action and institutional controls alternatives are ranked high for
technical feasibility, availability, and capital expenditures. However, the
failure to mitigate environmental and potential public health impacts far
outweighs these advantages.
7-31
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7.7 CONCLUSIONS
Sitcum Waterway was identified as a problem area because of the
elevated concentrations of the inorganic contaminants in sediment. Copper
and arsenic were selected as indicator chemicals to assess source control
requirements, evaluate sediment recovery, and estimate the area and volume
of sediment to be remediated. In addition to these indicator chemicals,
biological effects were also observed in Sitcum Waterway as a result of
elevated concentrations of nonindicator compounds. The volume of sediment
exceeding long-term cleanup goals for these compounds is estimated at
10,000 ycP. In this problem area, sediments with concentrations currently
exceeding long-term cleanup goals cover an area of approximately 167,000 yds
and a volume of 167,000 ycP. Some of this sediment is predicted to recover
within 10 yr following implementation of all known, available, and reasonable
source control measures, thereby reducing the contaminated sediment volume
by 101,000 yd^. The total volume of sediment requiring remediation is,
therefore, reduced to 66,000 yd^.
The primary identified and potential sources of problem chemicals to
Sitcum Waterway include the following:
• Terminal 7 ore unloading facilities
• Storm drains.
Source control measures required to correct these problems and ensure
the long-term success of sediment cleanup in the problem area include the
following actions:
• Reduce inputs of metal contaminants to the waterway from the
Terminal 7 facility via stormwater runoff and ore spillage
• Reduce the amount of metals and other contaminants to the
waterway from storm drain SI-172
• Investigate sources of contamination in other storm drains
and initiate appropriate source control measures to reduce
ongoing discharges
• Confirm that all significant sources of problem chemicals
have been identified and controlled
• Perform ongoing monitoring to evaluate the effectiveness of
best management practices at the ore unloading facilities.
It should be possible to control sources sufficiently to maintain
acceptable long-term sediment quality. This determination was made by
comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. Source control requirements were developed through application
of the sediment recovery model for the indicator chemicals arsenic and
7-32
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copper. If the potentially responsible parties demonstrate that implementa-
tion of all known, available, and reasonable control technologies will not
provide sufficient reduction in contaminant loadings, then the area
requiring sediment remediation may be re-evaluated.
Hydraulic dredging with nearshore disposal was recommended as the
preferred alternative for remediation of sediments that are not predicted to
recover within 10 yr of implementation of source controls. The selection
was made following a detailed evaluation of viable alternatives encompassing
a wide range of general response actions. Because sediment remediation will
be implemented according to a performance-based ROD, the alternative
eventually implemented may differ from the currently preferred alternative.
The preferred alternative meets the objective of providing protection for
both human health and the environment by effectively isolating contaminated
sediments at near in situ conditions in an engineered disposal facility
where performance monitoring can be readily implemented. Disposal sites for
nearshore confinement are available at this time. Use of material from
Sitcum Waterway in a nearshore facility is compatible with the Port of
Tacoma's industrial development plans, minimizing the impacts of using
another facility. Concerns regarding potential contaminant migration to an
adjacent fish mitigation area will be addressed through the placement of
contaminated material in a saturated environment and the ongoing monitoring
program to detect potential problems in sufficient time to implement
corrective measures. Nearshore disposal has been demonstrated to be
effective in isolating contaminated sediments (U.S. Army Corps of Engineers
1988). The alternative is consistent with the Tacoma Shoreline Management
Plan, Sections 404 and 401 of the Clean Water Act, and other applicable
environmental requirements.
As indicated in Table 7-5, hydraulic dredging with nearshore disposal
provides a cost-effective means of sediment mitigation. The estimated cost
to implement this alternative is $1,612,000. Environmental monitoring and
other O&M costs at the disposal site have a present worth of $139,000 for a
period of 30 yr. These costs include long-term monitoring of sediment
recovery areas to verify that source control and natural sediment recovery
have corrected the contamination problems in the recovery areas. The total
present worth cost of the preferred alternative is $1,751,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control.
7-33
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In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures.
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
and regulations, utilize the most protective solutions practicable, and are
cost-effective.
7-34
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8.0 ST. PAUL WATERWAY
Potential remedial actions are defined and evaluated in this section
for the St. Paul Waterway problem area. The waterway is described in
Section 8.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 8.2 provides an overview of contaminant
sources, including site background, identification of known and potential
contaminant reservoirs, remedial activities, and current site status. The
effects of source controls on sediment remediation are discussed in
Section 8.3. Areas and volumes of sediment requiring remediation are
discussed in Section 8.4. The detailed evaluation of the candidate sediment
remedial alternatives chosen for the problem area and indicator problem
chemicals is provided in Section 8.5. The preferred alternative is
identified in Section 8.6. The rationale for its selection is presented,
and the relative merits and deficiencies of the remaining alternatives are
discussed. The discussion in Section 8.7 summarizes the findings of the
selection process and integrates source control recommendations with the
preferred sediment remedial alternative.
8.1 WATERWAY DESCRIPTION
St. Paul Waterway is located between the Puyallup River to the north
and Middle Waterway to the south (Figure 8-1). St. Paul Waterway was
created in stages from 1920 to the early 1930s (Dames & Moore 1982). Early
charts indicate that the inner portion at the waterway was used for log
rafts and booms and was navigable to shallow draft boats. This part of the
waterway remained intertidal and was apparently never dredged (Tetra Tech
1985a). In the early 1960s, the head of the waterway was filled to create
the current configuration, which is about half its former size. Fill
material is believed to have come from the U.S. Army Corps of Engineers
dredging of the Puyallup River and may have included slash and sawdust from
forest products industries in the area (Dames & Moore 1982).
St. Paul Waterway is approximately 2,000 ft long. Its width ranges
from 400 ft at the head to 600 ft at the mouth (Tetra Tech 1985b). The
depth of St. Paul Waterway increases from the head toward the mouth with
fairly steep channel sides and mid-channel depths ranging from less than
10 ft below MLLW at the head to greater than 30 ft below MLLW at the mouth
(Raven Systems and Research 1984).
St. Paul Waterway is not a designated navigation channel. Sediments
within St. Paul Waterway are typically 50 percent fine-grained material,
with a clay content of nearly 10 percent (Tetra Tech 1985a). Total organic
carbon values for sediments in the waterway range from 1.5 to 16 percent.
Contaminants identified in the waterway are primarily organic compounds that
are relatively soluble and have low particle affinity (Tetra Tech 1987c).
8-1
-------
1 SIMPSON TACOMA KRAFT
2 SIMPSON TACOMA KRAFT (STUD Mil)
3 CHAMPION INTERNATIONAL (SAW MILL)
4 MORSE INDUSTRIAL SUPPLY
5 PAXPORT MILLS
6 WELLWOOD
Reference: Tacoma-Pierce County Health
Department (1984,1966).
Notes: Property boundaries are approximate
based on aerial photographs and drive-
by inspections.
meters
150
Figure 8-1. St. Paul Waterway - Existing industries, businesses,
and discharges.
8-2
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8.1.1 Nature and Extent of Contamination
Analysis of data collected during the RI and FS in conjunction with
historical data has revealed that St. Paul Waterway contains elevated concen-
trations of organic contaminants (Tetra Tech 1985a, 1986c). 4-Methylphenol
was identified as a Priority 1 contaminant in the waterway (see Section 1.3.5
for definitions of priority 1, 2, and 3 compounds). Priority 2 contaminants
that have been detected in the waterway include phenol, 2-methoxyphenol, and
1-methy1-2-(methylethyl) benzene. The following compounds exceeded their
corresponding AET values at only one station and are therefore considered
Priority 3 contaminants: naphthalene, 2-methylnaphthalene, biphenyl,
retene, diterpenoid hydrocarbons, nickel, total organic carbon, and total
volatile solids.
The primary goal of sediment remediation in St. Paul Waterway is the
isolation or removal of organic compounds observed at elevated concentrations
near the mouth of the waterway. 4-Methylphenol was selected as the organic
indicator compound. This compound is widespread in the problem area and is
expected to persist in the sediments.
Estimated area! and depth distributions of 4-methylphenol are shown in
Figure 8-2. Concentrations of 4-methylphenol exceeding the long-term cleanup
goal of 670 ug/kg extend over the entire mouth of the waterway. This
cleanup goal was set by the AET values derived for depressions in infaunal
abundance and the oyster larvae bioassay. The values shown in Figure 8-2
that are below 1.0 represent clean sediments based on the concentration of
4-methylphenol at the station, while the above 1.0 define problem sediments.
Depth profiles obtained from the two core stations suggest that 4-methylphe-
nol contamination exceeds the cleanup goal to a depth of approximately 2 yd,
with the highest concentrations occurring in the northeast corner of the
mouth of the waterway and declining toward the head.
8.1.2 Recent and Planned Dredging Projects
The Simpson Tacoma Kraft Company recently dredged approximately
6,500 yd-* of contaminated sediments in compliance with NPDES permit con-
ditions requiring relocation of the plant's outfall (SP-189 on Figure 8-1;
see Figure 8-3 for location of new outfall). The new outfall has been
placed at a depth of 70 ft below MLLW, and the first 220 ft are buried
beneath the sediment surface. Burial was required to provide stable support
for the pipe, to protect the pipe from wave action, and to address regulatory
concerns (Parametrix 1987). Contaminated dredged material, removed from the
path of the outfall by using a watertight clamshell, was placed in a
depression 16 ft below MLLW near the old outfall (see Figure 8-3). These
measures were completed in December 1987.
A second dredging project was performed for the barge unloading Di'er
near the northeast corner of the waterway. Approximately 1,000 yd^ of
sediment were dredged from the toe of the slope at the base of the pier in
February 1988. This material was placed in a second depression at 16 ft
below MLLW close to the first disposal site (see Figure 8-3). The depression
8-3
-------
4-METHYPHENOL (ng/kg)
o 9
5fi
5 o
I 1 1 I f 1 II I 1 I 1 1 1 I 1 I I I i 1
0 5 to 15 20 25 30
RATIO TO CLEANUP QOAL
— SP-91
-« SP-92
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDMENT SURVEYS CONDUCTED
IN 1984
SEDMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)*
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
Figure 8-2. Area) and depth distributions of 4-methylphenol in
sediments of St. Paul Waterway, normalized to long-term
cleanup goal.
8-4
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HABITAT
00
I
en
ENHANCEMENT \ S%¥.
\ SSi:
\ ::>x
\ SS&v.-..
SEQUENCE OF ACTIONS
Outfall Dredging (± 3,000 yd3)
Place Dredged Material in Depression
Outfall Preloading and Installation
Remove Old Outfall. Operate New Outfall
Chip Barge Dredging (± 3,000 yd3)
Race Dredged Material in Depression
Remove Old Pier and Other Piles
Construct Berm (± 12,000 yd3)
Place Sediment Cap*
Habitat Enhancement Over Cap*
Chip Containment
Stormwater Control and Treatment
9 and 10 Puyalkjp River Sediments
(± 200-300,000 yd3)
SHORELINE CONTOUR FILL
BERM (INITIAL PART OF CAP)
DREDGE AREA
REMEDIAL ACTION BOUNDARY
SEDIMENT REMEDIATION
Reference: Parametrix (1987)
Figure 8-3. Remedial actions at the Simpson Tacoma Kraft Company facility.
-------
was capped with clean fill from the Steilacoom Quarry. In the summer of
1988, the entire area was then capped 2-3 ft deep with approximately
238,000 yd3 of clean fill from the Puyallup River (Ficklin, J., 9 November
1988, personal communication).
8.2 POTENTIAL SOURCES OF CONTAMINATION
This section provides an overview of the sources of contamination to
the sediments in St. Paul Waterway and a summary of available loading
information for 4-methy1 phenol. Table 8-1 provides a summary of problem
chemicals and source status information for the problem area based on
information derived from the RI studies (Tetra Tech 1985b, 1986c). The major
source of contaminants that has been identified is the Simpson Tacoma Kraft
pulp mill. Surface sediment concentrations of nearly all problem chemicals
were greatest at Station SP-14, located immediately adjacent to the Simpson
outfall (SP-189). Storm drains discharging to the waterway are also
discussed in the section.
8.2.1 Simpson Tacoma Kraft Pulp Mill
Site Background--
The Simpson Tacoma Kraft Company occupies the peninsula between St. Paul
Waterway and the Puyallup River. Activities at the site date from 1889,
when the St. Paul and Tacoma Lumber Company began operations. The original
mill was constructed south of llth Street where a sawmill is currently
located. In 1940, the St. Regis Company purchased waterfront land from the
St. Paul and Tacoma Lumber Company and expanded its operation to the mouth
of the waterway. In 1959, St. Regis acquired the St. Paul and Tacoma Lumber
company. The pulp mill, located at the mouth of the waterway, and the
facilities surrounding St. Paul Waterway were purchased from St. Regis
Company by Champion International in 1984. The pulp mill was subsequently
purchased by Simpson Tacoma Kraft Company in August 1985 (Parametrix 1987).
To simplify discussion, contaminants from the area presently occupied by the
Simpson Tacoma Kraft pulp mill are described as associated with Simpson
operations, although Simpson only recently purchased the facility and some
of the data or reports cited predate the change in ownership.
Simpson Tacoma Kraft Company, as its name suggests, operates a pulp and
paper mill using the kraft process. Kraft pulping involves the use of
sodium hydroxide and sodium sulfide to delignify wood chips so that the
cellulose fibers can be separated. The mill produces unbleached Kraft
linerboard, unbleached Kraft paper, bleached paper, and bleached market pulp.
Prior to 1970, untreated plant effluent was discharged to the Puyallup
River. In late 1970, primary clarification was initiated and the outfall was
moved to its current location (SP-189). The mill began secondary treatment
of its wastewater in approximately 1975 (Fenske, F., 1 May 1987, personal
communication), using a UNOX activated sludge process. Sludge is dewatered
and burned in a hog fuel boiler at the mill. All sewers at the mill are
routed to the treatment facility, although not all wastewater from the
various mill processes pass through all stages of the treatment facility
8-6
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TABLE 8-1. ST. PAUL WATERWAY - SOURCE STATUS3
Chemical /Group
4-Methyl phenol
Phenol
2-Methoxyphenol
1 -Methyl -2-(methyl ethyl )-
benzene
Naphthalene
2-Methy 1 naphthal ene
Biphenyl
lotal organic carbon
Total volati le sol ids
Nickel
Oo 1 ilerpenoid hydrocarbons
1 Retene
Chemical
Priority1*
1
2
2
2
3
3 (SP-14)
3 (SP-14)
3 (SP-14)
3 (SP-14)
3 (SP-14)
3 (SP-14)
3 (SP-16)
Sources
Simpson Tacoma Kraft
(SP-189)
Puyallup River
Simpson Tacoma Kraft
Source ID Source Loading Source Status
Yes Source loadings Ongoing
available for
naphthalene only
Potential c c
Potential c c
Sediment Profile Trends
Variable
c
c
a Source information and sediment information blocks apply to all chemicals in the
respective group, not to individual chemicals only.
b For Priority 3 chemicals, the station exceeding AET is noted in parentheses.
c Not evaluated for this study.
-------
(Fenske, F., 1 May 1987, personal communication). Wastewaters with low
solids content (e.g., bleach plant wastewater, pump seal water) are routed
directly to the secondary treatment process to reduce the hydraulic loading
on the primary clarifiers. Limited information is available on the removal
efficiencies for various contaminants through the mill's treatment system.
Loading data for a 4-methylphenol are available from NPDES-permit monitoring
data, but there are few data points (see Appendix E, Table E-18).
During the RI (Tetra Tech 1985a) and subsequent work (Tetra Tech 1985b,
1986c), contaminants of concern found in the sediments of St. Paul Waterway
were determined to have originated from the mill. The mill is identified as
a source based on proximity to the problem area in St. Paul Waterway,
documented use of problem chemicals in mill processes, reduced concentrations
of contaminants in sediments with distance from the mill outfall, and the
presence of problem chemicals typically found in pulp mill effluents.
The mill has been identified as the major source of suspended organic
matter (Tetra Tech 1985a) and is the only identified source of phenol to
St. Paul Waterway (Tetra Tech 1986c). The mill is also an identified source
of chloroform, copper, and naphthalene. The mill effluent was implicated as
a source of 4-methylphenol based on the spatial distribution of 4-methyl-
phenol in sediments adjacent to the outfall and on the possibility that
4-methylphenol is a degradation product of 2-methylphenol, a compound often
found in pulp mill effluents (Tetra Tech 1985a). Subsequent analyses of the
effluent verified the presence of 4-methylphenol, the only St. Paul Waterway
sediment contaminant identified as Priority 1 in the RI (Tetra Tech 1985a).
Parametrix (1986) verified the presence of chlorinated phenolic compounds,
phthalate compounds, chloroform, copper, and zinc in the effluent.
Identification of Contaminant Reservoirs Onsite--
The primary source of contaminants to the St. Paul Waterway area
sediments from the mill site appears to be effluent from the wastewater
treatment facility (SP-189). Additional contaminant reservoirs or alter-
native pathways to the sediments have not been well characterized. There
are two storm drains on the mill site and two storm drains at the head of
St. Paul Waterway. Contaminant loadings from these drains have not been
quantified. At the time of this study, insufficient information was
available to characterize the relative importance of groundwater infiltration
and surface runoff as potential sources of sediment contamination.
Recent and Planned Remedial Activities--
Simpson recently proposed a comprehensive remedial action and habitat
restoration project in response to NPDES permitting requirements (Permit
No. WA-000085-0). The following actions are included in that project:
• Relocate the secondary treatment outfall
• CAD contaminated sediments and restore nearshore habitat
8-8
-------
• Control contaminant sources
• Monitor the effectiveness of implemented project measures.
The environmental studies and engineering plans for the proposed
outfall relocation, remedial action, and habitat restoration have been
reviewed and approved by Ecology.
Outfall Relocation—The Simpson permit requires relocation of the
existing secondary treatment outfall (SP-189), which has been the primary
source of sediment contamination in the area near the northeastern corner of
the site (see Figure 8-3).
Installation of the new outfall system was completed in March 1988. The
system is designed to provide a minimum design dilution ratio of 55:1 at a
discharge depth of 70 ft below MLLW. However, with variations determined by
tide stage, discharge rate, and other factors (Parametrix 1987) more common
initial dilution ratios of 70:1 are expected. The new 48-in outfall pipe
extends 920 ft offshore and terminates in a 180-ft long diffuser with
30 ports.
Sediment Remediation and Habitat Restoration—Simpson is planning to
cap contaminated sediments in the vicinity of the old plant outfall
(SP-189), eliminating exposure of biota and the water column to existing
contamination. A submerged berm will be constructed to ensure containment
of contaminated sediments, including dredged material from the outfall
realignment and pier projects. Cap material (clean fill from the Puyallup
River) will be placed over the contaminated sediments through a downpipe
diffuser for controlled discharge. The depth of the cap will range from
4 to 12 ft. An additional 4-8 ft of sand and silt from the Puyallup River
will be added to raise the sediment surface to intertidal or very shallow
subtidal depths, thus providing intertidal habitat with sediment character-
istics like those originally found in the area. The vicinity of the old
outfall will be filled to above the highest tidal level (18 ft above MLLW)
to provide maximum isolation and confinement of contaminated sediments
(Parametrix 1987). This fill element will allow surface water control in the
primary clarifier and hog fuel storage areas. The 0.6 ac of shallow-water
shoreline to be converted to terrestrial land will be covered by an
impervious surface, surrounded by a peripheral berm, and served by a runoff
collection system. This phase of the project is scheduled for completion in
August 1988.
Source Control (In-Piant)--Simpson has also initiated a contaminant
source control effort to reduce contaminant concentrations in discharges to
Commencement Bay to environmentally acceptable levels. The source control
program consists of the following four elements:
• Reduce levels of harmful impurities in purchased chemicals or
raw materials
• Treat runoff from plant processing areas
8-9
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• Contain woody debris and wood chip feedstocks
• Make process modifications to reduce the ultimate discharge of
harmful contaminants.
Although not named as priority chemicals for St. Paul Waterway during
the RI, copper, chloroform, and chlorine had been identified by Simpson and
Ecology as chemicals of potential concern.
Releases of chloroform, copper, and 4-methylphenol in plant discharge
have declined since the program began (Parametrix 1987). Modifications to
the mill's bleach plant are proposed over the next 2 yr to reduce chlor-
inated organics discharge in plant effluent. Copper loadings have been
reduced as a result of Simpson placing more stringent specifications on the
composition of Vanillin Black Liquor, a process material supplied by the
Monsanto Company. In October 1985, Simpson established a maximum acceptable
copper concentration of 60 mg/L for purchased Vanillin Black Liquor. In
March 1986, Simpson lowered the maximum allowable concentration to 10 mg/L.
According to Parametrix (1987), the annual input of copper from Vanillin
Black Liquor to the effluent has been reduced by greater than 99 percent
since 1985. Simpson has noted that additional minor contributions of copper
to this region of Commencement Bay originate from City of Tacoma water, the
Puyallup River, copper intrinsic in wood, and copper leached from process
pipes.
Copper concentration in the effluent is currently measured daily
(Fenske, F=, 1 May 1987, personal communication). Average total and
dissolved copper concentrations in secondary effluent samples are 51 ug/L
(n=275) and 26 ug/L (n=144), respectively. The average background copper
concentration in Commencement Bay is 8 ug/L. With the predicted dilution of
55:1, the copper concentration in the zone of initial dilution will be
approximately 8.3 ug/L. Both the acute and chronic marine water quality
criteria for copper are 2.9 ug/L. Simpson intends to conduct a rigorous
monitoring program at the zone of initial dilution to evaluate actual
dilution.
Discharge of 4-methylphenol from Simpson has reportedly decreased since
1986 (Parametrix 1987). Liquid salt cake (Na2S04J from Northwest Petro-
chemical was apparently a major source of phenolic compounds in the
effluent. Purchases of salt cake from Northwest Petrochemical were halted
in the fall of 1986. Future purchases of salt cake will be contingent upon
strict control of concentrations of phenols and other chemicals (e.g.,
cymenes). Parametrix (1987) estimated the annual contributions (ton/yr) of
nine contaminants (including phenol) contained in the liquid salt cake,
presumably to demonstrate that discontinuing use of this material would
result in a large decrease in the discharge of the contaminants. However,
neither the data from which the annual contributions were derived, nor the
reasoning behind the assumptions used to calculate the annual contribution
are provided in Parametrix (1987). In addition, contributions are attributed
to "total phenolics", and the individual contributions of discrete compounds
(e.g., 4-methylphenol) are not presented.
8-10
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Acute and chronic bioassays of effluent were conducted in winter and
spring of 1987. Results of the 96-h acute static bioassays on juvenile
rainbow trout (Salmo aardneri) using 100 percent effluent showed 80-100 per-
cent survival. In Ceriodaphnia chronic bioassays conducted on two samples
of effluent, the lowest-observed-effect concentration varied from 10 to
100 percent.
Stormwater Runoff Controls--Stormwater controls (i.e., paving, grading,
berms, and sumps) are being installed to collect and transport runoff from
the plant site to the secondary treatment facility (Ficklin, J., 2 July
1987, personal communication). When the remedial program was initiated,
runoff from the following areas discharged directly to the waterways
(Figure 8-4):
• Primary clarifier and hog fuel storage area discharged
directly to Commencement Bay
• Mill area adjacent to the Puyallup River discharged directly
to Puyallup River
• Paper mill parking area and roof drains discharged to
St. Paul Waterway (SP-269)
• Secondary treatment plant and parking area discharged to the
Puyallup River via a sump.
During 1987, a portion of the site along the Puyallup River was paved
and stormwater control facilities were installed. Under the remedial action
plan (Parametrix 1987), this project will be extended to the remainder of the
Simpson property along the Puyallup River (see Figure 8-3). In addition,
areas around the primary clarifier and the hog fuel storage area will be
filled and paved. Storm drains will be installed to collect and transport
runoff to the treatment facility. Existing storm drains (SP-269 and SP-819)
in the paper mill parking area will also be routed via a sump to the mill
treatment system. Construction of stormwater control facilities is
scheduled for completion in 1988.
Containment of Woody Materials—Construction of a new chip barge
unloading facility to eliminate spillage during unloading from barges was
completed during summer 1987. The chip storage piles were isolated from the
bay by a paved, bermed, and fenced roadway. To contain the fine, readily
suspended chip material, the area along the conveyor system adjacent to
St. Paul Waterway was also paved, bermed, and fenced. In addition, water
sprayers and conveyor belt brushes were added to minimize the resuspension
potential of the fine material during conveyance.
8.2.2 Storm Drains
Three storm drains currently discharge to St. Paul Waterway: SP-269,
SP-268-01, and SP-268-02 (Figure 8-5). Storm drain SP-269 collects surface
runoff from the parking area and roof drains at the Simpson paper mill and
was discussed in the previous section.
8-11
-------
00
I
•—I
ro
EXISTING
OUTFALL
(PRIMARY.
SECONDARY
TREATMENT)
PRIMARY
CLARIFIER
FORMER
OUTFALL
(UNTREATED)
180
,CAppEO)
BERMED.TO
TREATMENT PUYALLUP RIVER
PLANT
OUTFALL
AREA WHERE RUNOFF
WILL BE COLLECTED AND
ROUTED TO TREATMENT
PLANT;
RUNOFF COLLECTED
W SUMP, DISCHARGED
TO PUYALLUP RIVER
Reference: Parametrix (1987);
Ftahten, J. (2 July 1987,
personal communication).
Figure 8-4. Proposed stormwater control areas at the Simpson Tacoma Kraft Company facility.
-------
CD
»—•
OJ
LEGEND
100 200 300
IMIIII SURFACE DRAW
19 ^— OUTFALL AND DRAW NUMBER
—*• FLOW DIRECTION
Reference: Irotn Tacoma-Pierce County HeaHh Department (1963).
Figure 8-5. Surface water drainage pathways to St. Paul Waterway.
-------
The two remaining storm drains serve the area between the head of
St. Paul Waterway and East llth Street. Storm drain SP-268-01 serves
approximately 35 ac comprising the Commencement Bay Company log storage
facility and stud mill. In the past, SP-268-01 also drained a portion of
the old St. Regis property (approximately 25 ac) located on the south side
of llth Street. This latter area currently drains to Middle Waterway via
MD-200.
Discharge from SP-268-01 consists of stormwater runoff and noncontact
cooling water. The Commencement Bay Company currently discharges between
90,000 and 100,000 gal/day (0.14-0.15 ft3/sec) of cooling water to SP-268-01
(Corey, G., 6 August 1987, personal communication). The surface runoff
component of the discharge is estimated at roughly 60 ac-ft/yr (0.08 ft-Vsec)
based on an annual rainfall of 37 in (Norton and Johnson 1985a) and runoff
coefficient of 0.5 (Viessman et al. 1977). The Commencement Bay Company
plans to eliminate the discharge of cooling water to SP-268-01 by routing
flows to the Simpson secondary treatment plant. When the rerouting is
complete, the discharge from SP-268-01 will consist entirely of surface
water runoff.
Storm drain SP-268-02 drains the area to the west of the SP-268-01
drainage basin. However, the basin boundaries and contributing area are not
known.
Loading data for the contaminants of concern [i.e., phenol, 4-methyl-
phenol, 2-methoxyphenol, and 1-methyl-2-(methylethyl)benzene] in St. Paul
Waterway are not available for SP-268-01 and SP-268-02. However, estimates
derived from available sediment data suggests that these drains are not
currently contributing significant concentrations of problem chemicals to
St. Paul Waterway sediments. Existing data indicate that both storm drains
may be a source of solids loading to the waterway (Tetra Tech 1986c). Land
use in the drainage basins of both drains has historically been associated
with the forest products industry (i.e., sawmills and log storage yards).
In addition to wood wastes, surface runoff from the basins may have been
contaminated by glue because historically glue residues were commonly
disposed of on sawdust piles.
8.2.3 Loading Summary
There are very few loading data for discharges into St. Paul Waterway.
Source contaminant loading calculations presented in Appendix E, Table E-18,
and where possible have been updated to include data collected since the
completion of the Remedial Investigation (Tetra Tech 1985a, 1986c). Post-RI
loading data are available for the Simpson main outfall SP-189 (Parametrix
1987) and have been incorporated into the appendix.
8.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
8-14
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This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the effects of source control and natural
recovery processes were evaluated. This evaluation was based on the
sediment contaminant concentrations and assumptions regarding the relation-
ship between sources and sediment contamination. Included within the
evaluation was an estimate of the degree of source control needed to correct
existing sediment contamination problems over the long term.
8.3.1 Feasibility of Source Control
The main source associated with sediment contamination in St. Paul
Waterway is process effluents from the Simpson Tacoma Kraft Company pulp
mill.
The Simpson NPDES outfall (SP-189) was identified as a major source of
4-methylphenol and other chemicals (Tetra Tech 1985a). Available tech-
nologies for reducing process effluents (see Chapter 3) include primary and
secondary wastewater treatment outfall relocation, and in-plant contaminant
reduction through process changes and product substitution.
A number of these technologies have been implemented by Simpson Tacoma
Kraft and its predecessors. Primary and secondary wastewater treatment
systems were installed in 1963-64 and 1977, respectively. In March 1988,
Simpson completed construction of an extended outfall and diffuser system.
This system is expected to effectively eliminate the discharge of suspended
solids from the plant. Discharge at the -70 ft MLLW elevation with the
diffuser system and resultant minimum dilution of 55:1 are expected to
prevent flocculation and settling of suspended solids and dissolved
constituents in the plant effluent (Parametrix 1987). Moving the outfall to
an offshore site is also expected to minimize effluent transport toward the
shoreline (Parametrix 1987). Finally, the pulp mill has been effective in
minimizing the production of process contaminants and removing contaminants
from purchased chemicals (Parametrix 1987).
Continued operation of existing pollution measures and implementation
of additional in-plant controls is expected to result in a significant
reduction in contaminant discharges. Given the contaminant types, multi-
plicity of sources, and available control technologies, it is estimated that
implementation of all known, available, and reasonable control technologies
will reduce contaminant loading due to process effluent by up to 95 percent
(the maximum assumed feasible).
Because major contaminant sources or pathways other than the effluent
have not been positively identified or quantified and Simpson has implemented
or has planned control measures for sources such as runoff, no other source
controls are recommended at the pulp mill. Monitoring should be undertaken
to assess the effectiveness of the implemented source control measures and
to assess whether additional source control measures should be taken to
prevent further contamination of Commencement Bay and St. Paul Waterway.
8-15
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fl.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemical 4-methy1 phenol. Results are reported in
full in Tetra Tech (1987a). A summary of those results is presented in this
section.
The depositional parameters in St. Paul Waterway were estimated from
the overall depositional patterns observed for Commencement Bay. A sedimen-
tation rate of 1,000 mg/cm2/yr (0.70 cm/yr) and a mixing depth of 10 cm were
selected. This sedimentation rate is supported by the location of the
problem area seaward of the main waterway channel and an estimated reduction
in sediment loading with the relocation at the Simpson outfall. A single
indicator chemical, 4-methylphenol, was used to evaluate the effect of
source control and the degree of source control required for sediment
recovery. Two timeframes for sediment recovery were considered: a
reasonable timeframe (defined as 10 yr) and the long term. A decay constant
of 0.693 (i.e., a half-life of 1 yr) was used to illustrate the effect of
potential diffusive or biodegradative losses on sediment recovery (Tetra
Tech 1987a). However, the possibility of in situ production of 4-methyl-
phenol indicates that a more conservative assumption of no significant loss
may be more appropriate. Source loading of 4-methylphenol is assumed to be
in steady-state with sediment accumulation for the purposes of establishing
the relationship between source control and sediment recovery. This
assumption is conservative based on the extensive source control measures
that have been implemented or planned. Results of the source control
evaluation are summarized in Table 8-2.
Effects of Complete Source Elimination--
If sources are completely eliminated, a recovery time of 70 yr is
predicted for sediments contaminated with 4-methylphenol. Sediment recovery
is not possible in a reasonable timeframe (i.e., 10 yr), and sediment
remedial actions will be required.
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source control
is expected to reduce source inputs of 4-methylphenol by 95 percent. At
this .level of source control, the model predicts that sediments with an
enrichment ratio of 1.9 or less (i.e., 1,270 ug/kg or less of 4-methylphenol)
will recover to the long-term cleanup goal within 10 yr (Table 8-2). The
surface area of sediment not recovering to the cleanup goal within 10 yr is
shown in Figure 8-6. For comparison, sediments currently exceeding long-
term cleanup goals for indicator chemicals are also shown.
8-16
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TABLE 8-2. ST. PAUL WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemical
4-Methylphenol
Station with Highest Concentration
Station identification SP-14
Concentration (ug/kg dry weight) 96,000
Enrichment ratio3 143
Recovery time if sources are
eliminated (yr) 70
Percent source control required
to achieve 10-yr recovery NP"
Percent source control required
to achieve long-term recovery 99
Average of Three Highest Stations
Concentration (ug/kg dry weight) 38,900
Enrichment ratio3 58
Percent source control required
to achieve long-term recovery 98
10-Yr Recovery
Percent source control assumed
feasible 95
Highest concentration recovering
in 10 yr (ug/kg dry weight) 1,270
Highest enrichment ratio of sediment
recovering in 10 yr 1.9
a Enrichment ratio is the ratio of observed concentration to cleanup goal
b NP = Not possible.
8-17
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00
I
1-^
00
St. Paul Waterway
Indicator Chemical
AT PRESENT
DEPTH (yd)
AREA (yd 2)
VOLUME (yd 3)
IN 10 YR
DEPTH (yd)
AREA (yd 2)
VOLUME (yd 3)
2
118,000
236.000
2
87,000
174,000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)*
4-METHYLPHENOL (AET = 670 ng/kg)
* No data available.
Figure 8-6. Sediments in St. Paul Waterway not meeting cleanup goals for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that virtually all of the 4-methylphenol input must
be eliminated to maintain acceptable contaminant concentration in freshly
deposited sediments. However, the actual percent reduction required in
source loading is subject to the considerable uncertainty inherent in the
assumptions of the predictive model.
8.3.3 Source Control Summary
The major source of 4-methylphenol to St. Paul Waterway is believed to
be the Simpson Tacoma Kraft Mill effluent. If this source is completely
eliminated it is predicted that sediment concentrations of the chemical will
not decline to the long-term cleanup goal of 670 ug/kg until 70 yr have
passed. Sediment remedial action will therefore be required to attain
quality goals within a reasonable timeframe. The source control measures
that have been, or will be, implemented are expected to be effective in
maintaining adequate sediment quality following remediation. Ongoing
monitoring following the implementation of remedial actions will provide the
data necessary to confirm this assumption. The 3 percent difference between
required and achievable levels of control (see Table 8-2) is not expected to
be significant in light of the uncertainties inherent in the sediment
recovery model.
8.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with 4-methylphenol concentra-
tions exceeding the long-term cleanup goal is 236,000 yd^ (see Figure 8-6).
This volume was estimated by multiplying the areal extent of sediment
exceeding the cleanup goal (118,000 yd2) and the estimated 2-yd depth of
contamination (see sediment contaminant profiles in Figure 8-2). The
estimated thickness of contamination is only an approximation; few sediment
profiles were collected and the vertical resolution of these profiles was
poor at the depth of the contaminated horizon. For the volume calculations,
depths were overestimated. This approach was taken to reflect the fact that
depth to the contaminated horizon cannot be accurate dredged, to account for
dredge technique tolerances, and to account for uncertainties in sediment
quality at locations between the sediment profile sampling stations.
The estimated volume of sediment requiring remediation is 174,000 yd^,
based on the volume of sediment that is expected to exceed the 4-methylphenol
long-term cleanup goal 10 yr after implementing feasible levels of source
control. This value was calculated as the product of the area of sediment
with an enrichment ratio greater than 1.9 (87,000 yd2; see Table 8-2) and
the depth of contamination (2 yd; see Figure 8-2).
8.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
8.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
8-19
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remediation. In the following discussion, this set of alternatives is
evaluated to determine the suitability of each for the remediation of
contaminated sediments in St. Paul Waterway. The objective of this evalua-
tion is to identify the alternative considered preferable to all others
based on CERCLA/SARA criteria of effectiveness, implementability, and cost.
The first step in this process is to assess of the applicability of
each alternative to remediation of contaminated sediments in St. Paul
Waterway. Site-specific characteristics that must be considered in such an
assessment include the nature and extent of contamination; the environmental
setting; the location of potential disposal areas; and the site's physical
properties including waterway usage, bathymetry, and water flow conditions.
Alternatives that are determined to be appropriate for the waterway can then
be evaluated based on the criteria discussed in Chapter 4.
The indicator chemical 4-methylphenol was selected to represent inputs
from the primary sources of contamination to the waterway: the Simpson
Tacoma Kraft pulp mill and associated storm drains. Area! distribution of
the indicator chemical is presented in Figure 8-6 based on long-term cleanup
goals and estimated 10-yr sediment recovery. Sediment recovery estimates
indicate that a reduction of approximately 25 percent could be achieved in
10-yr with 95 percent control of sources.
The predominance of organic contamination in St. Paul Waterway sediments
indicate that a treatment process for organics is appropriate. The presence
of metals at a total concentration of less than 500 mg/kg would not be
expected to limit the applicability of solvent extraction, thermal treatment,
or land treatment. Alternatives incorporating these treatment processes are
evaluated for St. Paul Waterway. Solidification, however, is unlikely to be
successful because of the high concentrations of total organic carbon and
organic contaminants, and is therefore not evaluated.
It is assumed that the requirement to maintain navigational access to
the Puyallup River and Sitcum Waterway could preclude the use of a hydraulic
pipeline for nearshore disposal at the Blair Waterway disposal site.
Therefore, clamshell dredging has been chosen for evaluation in conjunction
with the nearshore disposal alternative.
Nine of the 10 sediment remedial alternatives are evaluated below for
the cleanup of St. Paul Waterway:
• No action
• Institutional controls
• In situ capping
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
8-20
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• Clamshell dredging/solvent extraction/upland disposal
• Clamshell dredging/incineration/upland disposal
• Clamshell dredging/land treatment.
8.5.2 Evaluation of Candidate Alternatives
The three primary evaluation criteria are effectiveness, implement-
ability, and cost. A narrative matrix assessing each alternative based on
effectiveness and implementability is presented in Table 8-3. A comparative
evaluation of alternatives based on ratings of high, moderate, and low in
the various subcategories of evaluation criteria is presented in Table 8-4.
These subcategories are short-term protectiveness; timeliness; long-term
protectiveness; reduction in toxicity, mobility, or volume; technical
feasibility; institutional feasibility; availability; capital costs; and O&M
costs. Remedial costs are shown for sediments currently exceeding long-term
cleanup goal concentrations and for sediments that would still exceed the
cleanup goal concentrations 10 yr after implementing feasible source
controls (i.e., 10-yr recovery costs).
Short-Term Protectiveness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
biological and potential public health impacts continue if the contaminated
sediments remain in place unaltered. Source control measures initiated as
part of the institutional controls would result in reduced sediment
contamination with time, but adverse impacts would persist in the interim.
The clamshell dredging/land treatment alternative is also rated low for this
criterion; 4-methylphenol has a relatively high solubility [2.5 g/100 ml of
water at 50° C (Windholz et al. 1983)] which enhances its potential for
migration from the treatment site.
The clamshell dredging/nearshore disposal alternative is rated moderate
for short-term protectiveness primarily because nearshore intertidal habitat
could be lost in siting the disposal facility. The clamshell dredging/con-
fined aquatic disposal and hydraulic dredging/upland disposal options also
are assigned a moderate rating. The potential for enhanced partitioning to
the water column during hydraulic dredging or subaquatic disposal of
sediments containing a relatively soluble compound with low particle
affinity (Tetra Tech 1987c) may result in water column and environmental
impacts and contaminant redistribution during dredging. Alternatives
involving treatment (except land treatment) received moderate ratings for
short-term protectiveness because all involve additional dredged material
handling, longer implementation periods, and increased air emissions which
increase potential worker exposure. The hazards inherent in the solvent
extraction and incineration treatment processes themselves are also con-
siderable. The use of a watertight clamshell dredge for excavation may
enhance protectiveness during implementation. However, the potential
material handling hazards would tend to moderate any improvement that may be
8-21
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EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
ERM PROTECTIVENESS
H
6
o
_i
(CONTAMINANT
MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 8-3. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE ST. PAUL WATERWAY PROBLEM AREA
NO ACTION
MA
NA
Original contamination remains.
Source Inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative is ranked
ninth overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food spedes remains.
Original contamination remains.
Source Inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxidty and contam-
inant mobllty are expected to
remain at current levels or
increase as a result of continued
source inputs. Contaminated
sediment volume Increases as
a result of continued source
Inputs.
: INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
Source control is Implemented
and would reduce sediment con-
tamination with time, but ad-
verse Impacts would persist In
the interim.
Access restrictions and mon-
itoring efforts can be implement-
ed quickly. Partial sediment
recovery Is achieved naturally,
but significant contaminant
levels persist. This alternative
is ranked eighth overall for
timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source Inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source Input reductions
and sediment recovery. Con-
taminant moblity is unaffected.
IN SITU
CAPPING
Community exposure is not a
concern In the implementation
of this alternative. COM expo-
sure and handling are minimal.
Workers are not exposed to
contaminated sediments.
Contaminant redistribution is
minimized. Existing contami-
nated habitat Is destroyed and
replaced with clean material.
Rapid recolonization Is expect-
ed.
In situ capping can be implement
ed quickly. Pre-implementation
testing and modeling may be nee
essary, but minimal time is re-
quired. Equipment is available
and disposal siting issues should
not delay implementation. This
alternative is ranked first for
timeliness.
The long-term reliability of the
cap to prevent contaminant re-
exposure In the absence of
physical disruption is consi-
dered good.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating contami-
nated sediments from the over-
lying biota. Protection Is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM Is maintained at in
situ conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremedlation
levels.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure Is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM In-
creases exposure potential
moderately over hydraulic dredg-
ing. Removal with dredge and
disposal with downpipe and dif-
fuser minimizes handling require-
ments. Workers wear protective
gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment with
low particle affinity is resus-
pended during dredging opera-
tions. Benthic habitat Is impact-
ed at the disposal site.
Equipment and methods used
require no development period.
Pre-implementation testing Is
not expected to be extensive.
This alternative is ranked t
third overall for timeliness. "
The long-term reliability of the
cap to prevent contaminant re-
exposure in a quiescent, sub-
aquatic environment is consi-
dered acceptable.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating contami-
nated sediments from the over-
lying biota. Protection is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment.
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at In
situ conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM to a barge offshore during
transport. Public access to
dredge and disposal sites is re-
stricted. Public exposure po-
tential is low.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Workers wear pro-
tective gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Nearshore intertidal habitat
Is lost Contaminated sediment
Is resuspended.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment is available and disposal sit-
ing issues are not likely to delay
implementation. This alternative
is ranked second for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM.
Varying physicochemlcal con-
ditions In the fill may Increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment The
potential for contaminant migra-
tion into marine environment
may Increase over CAD. Adja-
cent fish mitigation site is sen-
sitive area. Nearshore site Is
dynamic In nature.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. Altered
conditions resulting from
dredge/disposal operations
may increase mobility of metals.
Volume of contaminated sedi-
ments is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM Is confined to a pipeline
during transport Public access
to dredge and disposal sites Is
restricted. Exposure from COM
spills or mishandling is possible,
but overall potential Is low.
Hydraulic dredging confines
COM to a pipeline during trans-
port Dredge water contamina-
tion may Increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment with
low particle affinity Is resus-
pended during dredging opera-
tions. Dredge water can be
managed to prevent release of
soluble contaminants.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked fourth
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating COM. Al-
though the potential for ground-
water contamination exists, It is
minimal. Upland disposal facili-
ties are more secure than near-
shore facilities.
Upland disposal Is secure, with
negligible potential for environ-
mental impact if property de-
signed. Potential for ground-
water contamination exists.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals Is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may increase due to resuspen-
sion of sediment
CLAMSHELL DREDGE/
SOLVENT EXTRACTION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment and disposal sites is re-
stricted. Extended duration of
treatment operations may result
in moderate exposure potential.
Additional COM handling asso-
ciated with treatment Increases
worker risk over dredge/disposal
options. Workers wear protec-
tive gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations.
Bench and pilot scale testing
are required. Full scale equip-
ment is available. Once ap-
proval is obtained, treatment
should be possible within 2
years. This alternative is rank-
ed fifth overall for timeliness.
Treated COM low in, metals can
be used as inert construction
material or disposed of at a
standard solid waste landfill.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal. Perma-
nent treatment for organic con-
taminants is effected.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal. Residual
contamination is reduced below
harmful levels.
Harmful contaminants are re-
moved from COM. Concen-
trated contaminants are dis-
posed of by RCRA- approved
treatment or disposal. Toxicity
and mobility considerations are
eliminated. Volume of contami-
nated material Is substantially
reduced.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment, and disposal sites is re-
stricted. Extended duration of
treatment operations may result
In moderate exposure potential.
Incineration of COM is accom-
plished over an extended period
of time thereby Increasing ex- "
posure risks. Workers wear pro-
tective gear.
Existing contaminated habitat
is destroyed by dredging but re-
covers rapidly. Sediment Is re-
suspended during dredging op-
erations. Process controls are
required to reduce potential air
emissions.
Substantial COM testing and
incinerator installation time is
required before a thermal treat-
ment scheme can be imple-
mented. Once approval is ob-
tained, treatment should be pos-
sible within 2 years. This alter-
native is ranked sixth overall for
timeliness.
Treated COM low in metals can
be used as inert construction
material or disposed of at a
standard solid waste landfill.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial. Volume of contaminated ma-
terial is substantially reduced.
CLAMSHELL DREDGE/
LAND TREATMENT
Public access to dredge and dis-
posal sites is restricted, dam-
shell dredging, land transport,
and extended duration of treat-
ment operations in open environ-
ment raise exposure risks.
Land treatment of COM Is ac-
complished over an extended
period of time thereby increas-
ing worker exposure. COM Is
tilled Into the treatment soil.
Exposure potential decreases
with time as degradation occurs.
Existing contaminated habitat
Is destroyed by dredging but re-
covers rapidly. Sediment is re-
suspended during dredging op-
erations. Contaminant has re-
latively high solubility which en-
hances its potential for migra-
tion from the treatment site.
Substantial testing would be re-
quired on the degradabillty of
contaminants and to determine
optimal operating conditions.
Treatment would probably require
a demonstration project, a long
treatment period, and a closure
phase. This alternative is ranked
seventh overall for timeliness.
Liner, run-on, and runoff controls
reliable. Potential system failure
becomes less critical with time,
as treatment progresses.
There is potential for public
health impacts as a result of
contaminant migration from
treatment facility. COM Is not
confined.
Design features of land treat-
ment system preclude contami-
nant migration to groundwater or
surface water. Control of vola-
tile emissions is limited.
Treatment of degradable organic
compounds eliminates this
component of COM toxicity.
Metals are not treated. Mobility
of metals may be enhanced by
aerobic soil conditions.
8-22
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| IMPLEMENTABILITY |
TECHNICAL FEASIBILITY
INSTITUTIONAL FEASIBILTY
1 AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH ARABS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 8-3. (CONTINUED)
NO ACTION
Implementation of this alterna-
tive Is feasible and reliable.
No monitoring over and above •,
programs established under
other authorities is implemented.;
There are no O & M requirements
associated with the no action
alternative.
This alternative is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels In sediments are ex-
ceeded. No permit requirements
exist This alternative fails to
meet the intent of CERCLA/
SARA and NCP because of on-
going impacts.
All materials and procedures are
available.
INSTITUTIONAL
CONTROLS
Source control and Institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be identified.
Sediment monitoring schemes
can be readily Implemented.
Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
Some O a M is associated with
monitoring, maintenance of
warning signs, and Issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels In sedimens are ex-
ceeded. This alternative fails to
meet Intent of CERCUVSARA
and NCP because of ongoing
impacts. State requirements
for source control are achieved.
Coordination with TPCHD for
health advisories for seafood
consumption Is required.
All materials and procedures are
available to implement Institu-
tional controls.
IN srru
CAPPING
Clamshell dredges and diffuser
pipes are conventional and reli-
able equipment In situ capping
Is a demonstrated technology.
Confinement reduces monitoring
requirements In comparison to
institutional controls. Sediment
monitoring schemes can be
readily Implemented.
O & M requirements are minimal.
Some O & M is associated with
monitoring for contaminant mi-
gration and cap Integrity.
Approvals from federal, state,
and local agencies are feasible.
WISHA/OSHA worker protection
is required. Substantive as-
pects of CWA and shoreline
management programs must
be addressed. This alternative
complies with U.S. EPA's on-
site disposal policy.
Equipment and methods to im-
plement this alternative are
readily available.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment
is reliable. Placement of dredge
and capping materials difficult,
although feasible. Inherent diffi-
culty In placing dredge and cap-
ping materials at depths of 100 ft
or greater.
Confinement reduces monitoring
requirements In comparison to
Institutional controls. Sediment
monitoring schemes can be
readily Implemented.
O & M requirements are minimal.
Some O & M is associated with
monitoring for contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM Is treated.
WISHA/OSHA worker protection
Is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Availability of open
water CAD sites is uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
Is reliable. Nearshore confine-
• ment of COM has been success-
fully accomplished.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes. Moni-
toring Imptementability Is en-
hanced compared with CAD.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facil-
ity siting are assumed feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been iden-
tified and is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
Is reliable. Secure upland con-
finement technology Is well de-
veloped.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring over CAD. Installa-
tion of monitoring systems Is
routine aspect of facility siting.
O a M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Coordination Is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to Im-
plement alternative are readily
available. Potential upland dis-
posal sites have been Identified
but none are currently available.
CLAMSHELL DREDGE/
SOLVENT EXTRACTION
UPLAND DISPOSAL
Although still In the develop-
mental stages, sludges, soils,
and sediments have success-
fully been treated using this
technology. Extensive bench-
and pilot-scale testing are likely
to be required.
Monitoring Is required only to
evaluate the reestabllshment
of benthic communities. Moni-
toring programs can be readily
Implemented.
No O A M costs are Incurred at
the conclusion of COM treat-
ment System maintenance Is
intensive during Implementation.
Approvals depend largely on re-
sults of pilot testing and the na-
ture of treatment residuals.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Complies with policies for
permanent reduction In contami-
nant mobility. Requires RCRA
permit for disposal of concen-
trated organic waste.
Process equipment available.
Disposal site availability Is not a
arimary concern because of re-
duction in hazardous nature of
material.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Incineration systems capable o
handling COM have been de*
vetoped, but no applications In-
volving COM have been report-
ed. Effects of salt and moisture
content must be evaluated. Ex-
tensive bench- and pilot-scale
testing are likely to be required.
Disposal site monitoring is not
required If treated COM Is deter-
mined to be nonhazardous. Air
quality monitoring Is intensive
during Implementation.
No O a M costs are Incurred at
the conclusion of COM treat-
ment System maintenance Is
Intensive during implementation.
Approvals for Incinerator opera-
tion depend on pilot testing and
ability to meet air quality stan-
dards.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Complies with policies for
permanent reduction In contami-
nant toxicity and mobility. Re-
quires compliance with PSAPCA
standards.
Incineration equipment can be
installed onsite for COM re-
mediation efforts. Applicable
Incinerators exist Disposal site
availability is not a concern be-
cause of reduction in hazardous
nature of material.
CLAMSHELL DREDGE/
LAND TREATMENT
Land treatment Is a demon-
strated technology for materials
contaminated with degradaWe
organic compounds. Extensive
bench- and pilot-scale testing
are likely to be required.
Monitoring programs can be
readily Implemented. Extensive
monitoring Is required during
active treatment period, with
less required during dosunt.
O a M consists of maintaining
monitoring equipment optimal
soil conditions, tilling equipment
and groundskeeping. Site In-
spections are required.
Treatment facility siting and
operation require extensive
agency review prior to approval.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's policy for toxicity
reduction and onsfte disposal.
Availability of land treatment
site Is uncertain.
8-23
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TABLE 8-4. EVALUATION SUMMARY FOR ST. PAUL WATERWAY
No Action
Short -Term
Protect iveness Low
Timeliness Low
Long-Term
Protect iveness Low
Reduction in Toxicity,
Mobility, or Volume Low
Technical Feasibility High
oo
• Institutional
52 Feasibility Low
Availability High
Long-Term Cleanup
Goal Cost8
Capital
O&M
Total
Long-Term Cleanup
Goal with 10- vr
Recovery Cost
Capital
O&M
Total
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
1.142
1.148
6
876
882
In Situ
Capping
High
High
High
Low
High
Moderate
High
909
1.317
2.226
672
1.282
1.954
Clamshell/
CAD
Moderate
Moderate
High
Low
Moderate
Moderate
Moderate
1.825
293
2,118
1,341
218
1.559
Clamshell/
Nearshore
Disposal
Moderate
High
Moderate
Low
High
Moderate
High
5.749
311
6.060
4.234
231
4.465
Hydraulic/
Upland
Di sposal
Moderate
Moderate
Moderate
Low
High
Moderate
Moderate
10,281
475
10,756
7,568
352
7,920
Clamshell/
Extraction/
Upland
Di sposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
49,841
453
50,294
36.742
335
37.077
Clamshell/
Incinerate/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
113.348
453
113.801
83,566
335
83,901
Clamshell/
Land
Treatment
Low
Low
Moderate
Moderate
Moderate
Moderate
Low
8.295
294
8.589
6.154
222
6.376
a All costs are in $1.000.
-------
realized by reduced sediment resuspension. Studies conducted by Parametrix
(1987) as part of the Simpson Tacoma Kraft remedial action effort have also
suggested the possibility that hydrogen sulfide is present in the predomi-
nantly anaerobic sediments in the problem area. This factor may result in
an air quality problem when staging materials for the treatment alternatives.
The in situ capping alternative rated high for short-term protective-
ness. With in situ capping the contaminated sediments are left in place,
which eliminates the potential for public or worker exposure. Contaminant
redistribution is also minimized.
Timeliness--
The no-action, institutional controls, and land treatment alternatives
received low ratings for timeliness. With no action, sediments remain
unacceptably contaminated, source inputs continue, and natural sediment
recovery is unlikely. Source inputs are controlled under the institutional
controls alternative but as discussed in Section 8.3.2, sediment recovery
based on the indicator contaminant 4-methylphenol is estimated to be
improbable within 10 years. Land treatment would probably require a
demonstration project, a relatively long treatment period, and a closure
phase. Approval and siting considerations are likely to adversely affect
the timeliness of this alternative.
Moderate ratings are assigned to all treatment alternatives, except land
treatment, and to the dredge alternatives involving upland and confined
aquatic disposal. Approval, siting, and development of upland or confined
aquatic disposal sites is estimated to require a minimum of 1-2 yr to
complete. However, equipment and methods used require no development
period, and pre-implementation testing is not expected to be extensive.
These conditions suggest that the upland and confined aquatic disposal
alternatives can be accomplished in a much shorter period of time if
treatment is not involved. The solvent extraction and incineration alter-
natives are likely to require a period of extensive testing before being
accepted. However, once approval is obtained, treatment of the contaminated
sediments in St. Paul Waterway should be possible within approximately 2 yr,
assuming maximum treatment rates of 420 yd-Vday (see Section 3.1.5).
The capping and nearshore disposal alternatives are rated high for
timeliness. Pre-implementation testing and modeling may be necessary to
evaluate potential releases caused by dredging and contaminant migration
through the cap, but such testing is not expected to require an extensive
period of time. Equipment and methods are readily available, and disposal
siting issues are less likely to delay implementation than for alternatives
involving upland and confined aquatic disposal.
Long-Term Protect!veness--
The evaluation for long-term protectiveness results in low ratings for
the no-action and institutional controls alternatives because the timeframe
for sediment recovery is long. For the latter alternative, the potential
for exposure to contaminated sediments remains, albeit at declining levels
8-25
-------
following implementation of source reductions. The observed adverse
biological impacts continue.
Moderate ratings are assigned to the clamshell dredging/nearshore and
hydraulic dredging/upland disposal alternatives based on the relatively high
solubility and migration potential of 4-methylphenol. Physicochemical
changes may also affect the migration potential of 4-methy1 phenol. However,
these effects would not be as significant as those for inorganic materials
and can be minimized by placing contaminated dredged material below the MLLW
level. Dredged material testing should provide the necessary data on the
magnitude of these impacts. Although the structural reliability of the
nearshore facilities is regarded as good, the nearshore environment is
dynamic in nature (i.e., from wave action and tidal influences). Even
though the upland disposal facility is generally regarded as a more secure
option because of improved engineering controls during construction, the
potential for impacts on area groundwater resources offsets the improvement
in long-term security. Although the alternative involving land treatment
should be effective in degrading this organic contaminant, a moderate rating
was assigned to reflect the potential for contaminant migration. In
addition, the Oil and Hazardous Materials/Technical Assistance Data System
(OHMTADS) indicates that 4-methylphenol exhibits significant toxicity
potential in both freshwater and marine environments.
Because the solvent extraction and incineration alternatives are
expected to be highly effective in treating 4-methylphenol contamination
based on the physicochemical properties of the compound, a high rating for
long-tern) protectiveness was assigned. The treated solids could be confined
in a standard landfill, assuming that the material is considered non-
hazardous. Both the in situ capping and confined aquatic disposal alter-
natives are also rated high for long-term protectiveness. Isolation of
contaminated material in the subaquatic environment provides a high degree
of protection, with little potential that sensitive environments will be
exposed to sediment contaminants. Currents and wave energy are thought to be
low in the problem area based on the presence of a sandbar from the Puyallup
River delta in the vicinity of the contaminated sediments and the presence
of high percentages of fine-grained material (Parametrix 1987). Relocation
of the NPDES outfall is expected to result in increased deposition of
Puyallup River sediments. In addition, confinement under in situ conditions
aids in maintaining the physicochemical conditions of the contaminated
sediments, thereby minimizing potential contaminant migration.
Reduction in Toxicity, Mobility, or Volume--
Low ratings have been assigned to all alternatives under this criterion,
except those involving treatment. Although capping, confined aquatic
disposal, upland, and nearshore disposal alternatives isolate contaminated
sediments from the surrounding environment, the chemistry and toxicity of
the material itself would remain largely unaltered. For nearshore and
upland disposal alternatives, the mobilization potential for untreated
dredged material may actually be increased by physicochemical changes.
Without treatment, the toxicity of contaminated sediments would remain at
preremediation levels. Contaminated sediment volumes would not be reduced,
8-26
-------
and, with hydraulic dredging options, may actually increase because of
suspension of the material in an aqueous slurry.
The land treatment alternative received a moderate rating for this
criterion based on the potential for leaching or migration of contaminants
from the treatment facility. Although run-on and runoff controls would be
incorporated, 4-methylphenol is soluble and its potential toxicity would
cause significant hazards if the compound migrated off-site.
Alternatives involving extraction and incineration would effectively
remove or destroy organic contaminants and therefore received high ratings.
These treatment systems should produce an effective reduction in the toxicity
and mobility of sediments through the removal (solvent extraction) or
destruction (incineration) processes. The solvent extraction process also
concentrates contaminants into a small volume of residual material. Bench-
scale testing of treatment residuals should provide data to substantiate or
invalidate these conclusions.
Technical Feasibility--
Alternatives involving treatment received only moderate ratings for the
criterion of technical feasibility because the treatment processes have never
been applied to sediment remediation. All processes are believed to be
suitable for this application, but lack of experience and demonstrated
performance in the use of these processes for treatment of contaminated
dredged material warrants caution. Extensive bench- and pilot-scale testing
are likely to be required before the technical feasibility of treatment via
solvent extraction, incineration, or land treatment could be assured. A
moderate rating was also assigned to the option for dredging with confined
aquatic disposal at an open-water site. Placement of dredge and capping
materials at depths of approximately 100 ft is difficult, although feasible.
Considerable effort and resources may be required to monitor the effective-
ness and accuracy of dredging, disposal, and capping operations.
High ratings are warranted for the remaining alternatives because the
equipment, technologies, and expertise required for implementation have been
developed and are readily accessible. The technologies constituting these
alternatives have been demonstrated to be reliable and effective elsewhere
for similar operations.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods are applied for all alternatives. The
intensity of the monitoring effort, which varies with uncertainty about
long-term reliability, does not influence the feasibility of implementation.
Institutional Feasibility--
The no-action and institutional controls alternatives were assigned low
ratings for institutional feasibility because compliance with CERCLA/SARA
8-27
-------
mandates would not be achieved. Requirements for long-term protection of
public health and the environment would not be met by either alternative.
Moderate ratings were assigned to the remaining alternatives because of
potential difficulty obtaining agency approvals for disposal sites or
implementation of treatment technologies. Although several potential
confined aquatic and upland disposal sites have been identified in the
project area, significant uncertainty remains with the actual construction
and development of the sites. In addition, excavation and disposal of
untreated contaminated sediment is discouraged by recent RI/FS guidance
documents (U.S. EPA 1988b). Agency approvals or granting of permits is
assumed to be contingent upon a bench-scale demonstration of effectiveness
in meeting established performance goals.
Availability--
Sediment remedial alternatives that can be implemented using existing
equipment, expertise, and disposal or treatment facilities are rated high
for availability. Because of the nature of the no-action and institutional
controls alternatives, equipment and siting availability are not obstacles
to implementation. Disposal site availability is not an obstacle to
implementation of the in situ capping alternative because the disposal site
is the contaminated site. The nearshore disposal alternative received a high
rating because it was assumed that the Blair Waterway site would be
available.
Remedial alternatives with upland or confined aquatic disposal are
rated moderate because of the uncertainty associated with disposal site
availability. Candidate alternatives were developed by assuming that sites
identified in a U.S. Army Corps of Engineers survey (Phillips et al. 1985)
will be available. However, no sites are currently approved for use and no
sites are currently under construction. Equipment availability is not
expected to preclude implementation of either the solvent extraction or
incineration alternatives.
The availability of a land treatment site suitable for the remediation
of contaminated dredged material is even less certain than that for
conventional nearshore and upland disposal sites. Therefore, land treatment
received a low rating for the availability criterion.
Costs--
Capital costs increase with increasing complexity (i.e., from no action
to the treatment options). This increase reflects the need to site and
construct disposal facilities, develop treatment technologies, and implement
alternatives requiring extensive contaminated dredged material or dredge
water handling. Costs for hydraulic dredging/upland disposal are sig-
nificantly higher than those for clamshell dredging/nearshore disposal,
primarily due to underdrain and bottom liner installation, dredge water
clarification, and use of two pipeline boosters to facilitate contaminated
dredged material transport to the upland site. The cost of the extraction
alternative increases because of materials for the process, and labor for
8-28-
-------
material handling and transport. Clarification and dredge water management
costs are also incurred for this option.
A major component of O&M costs is the monitoring requirements associated
with each alternative. The highest monitoring costs are associated with
alternatives involving the greatest degree of uncertainty for long-term
protectiveness (e.g., institutional controls), or where extensive monitoring
programs are required to ensure long-term performance (e.g., in situ
capping, confined aquatic disposal). Costs for monitoring of in situ
capping and the confined aquatic disposal facility are significantly higher
because of the need to collect sediment core samples at multiple stations,
with each core being sectioned to provide adequate depth resolution.
Nearshore and upland disposal options, on the other hand, use monitoring
well networks requiring the collection of only a single groundwater sample
at each well to assess containment migration.
It is also assumed that the monitoring program will include analyses
for all contaminants of concern (exceeding AET values) in the waterway.
This approach is conservative and could be modified to reflect use of key
chemicals to track performance. Monitoring costs associated with the
treatment alternatives are significantly lower because the process results
in lower contaminant migration potential.
8.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the preceding evaluation of nine candidate remedial alterna-
tives for St. Paul Waterway, in situ capping has been recommended as the
preferred alternative for sediment remediation. Because sediment remediation
will be implemented according to a performance-based ROD, the specific
technologies identified in this alternative (i.e., in situ capping) may not
be the technologies eventually used to conduct the cleanup. New and
possibly more effective technologies available at the time remedial
activities are initiated may replace the alternative that is currently
preferred. However, any new technologies must meet or exceed the performance
criteria (e.g., attainment of specific cleanup criteria) specified in the
ROD. Because the waterway is shallow and is not designated for use in
commercial shipping, in situ capping would provide a high degree of protec-
tiveness and may also improve valuable nearshore habitat. By preserving the
physicochemical conditions of the contaminated sediments and not disturbing
material, this alternative would result in lowered potential for migration
or redistribution of the relatively soluble contaminant 4-methylphenol,
compared with alternatives involving dredging. The weak particle affinities
exhibited by the organic contaminants may enhance migration potential during
dredging as well. Bench-scale sediment column studies should be conducted
to quantify contaminant mobilization potential and provide a basis for deter-
mining cap thickness. Capping contaminated sediments in St. Paul Waterway
is expected to provide reliable long-term protection of both public health
and the environment. The alternative may also serve to enhance the estuarine
habitat in the area. The alternative can be readily implemented with
available equipment, which has been used for in situ capping and as an
element of confined aquatic disposal. Monitoring to evaluate long-term
performance of the cap would not pose technical difficulties. With a total
8-29
-------
estimated cost of approximately $2.0 million (including initial costs and
the present worth of a 30-yr monitoring and O&M program), in situ capping
also appears to be cost-effective.
In situ capping rates high for all evaluation criteria except institu-
tional feasibility (moderate) and reduction in toxicity, mobility, or volume
(low). No other alternative received as many high ratings as in situ
capping.
In comparison to confined aquatic, nearshore, and upland dredging and
disposal alternatives, in situ capping eliminates exposure risks that
accompany dredging of contaminated materials. From a contaminant mobility
standpoint, the maintenance of in situ conditions is preferable to the
physicochemical changes that can occur in nearshore and upland environ-
ments. In situ capping also eliminates the potential for excessive
partitioning of contaminants to the water column as a result of sediment
disturbance. The uncertainties associated with upland and confined aquatic
disposal site availability and the bias against landfilling of untreated
CERCLA/SARA waste lower the overall ratings of these dredge/disposal
alternatives. The possibility of gaining nearshore habitat as a result of
capping compares favorably with potential losses of nearshore habitat
arising from implementation of a nearshore disposal alternative.
Treatment-based remedial alternatives were not considered preferable to
capping because they would take longer to implement and cost $4.4 million to
$82 million more to implement. If treatability testing revealed that
incinerated or solvent-extracted solid residues were nonhazardous, these
treatment alternatives would provide a better long-term protectiveness and
greater reductions in toxicity and mobility. However, in situ capping can
likely provide adequate protectiveness cost-effectively.
The no-action and institutional controls alternatives were not selected
because their implementation would not meet long-term cleanup goals.
8.7 CONCLUSIONS
St. Paul Waterway was identified as a problem area because of the
elevated concentrations of several organic contaminants in sediments. The
compound 4-methylphenol was selected as the indicator chemical to assess
source control requirements, evaluate sediment recovery, and estimate the
area and volume to be remediated. In this problem area, sediments with
concentrations currently exceeding long-term cleanup goals cover an area of
approximately 118,000 yd2, and a volume of 236,000 yd3. Of the total
sediment area currently exceeding cleanup goals, 31,000 yd2 is expected to
recover within 10 yr following implementation of all known, available, and
reasonable source control measures, thereby reducing the contaminated
sediment volume by 62,000 yd3. The total volume of sediment requiring
remediation is, therefore, reduced to 174,000 yd3.
The primary identified source of problem chemicals to St. Paul Waterway
is the Simpson Tacoma Kraft facility. Source control measures required to
8-30
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correct the identified problems, and ensure the long-term success of sediment
cleanup in the problem area include the following actions:
• Control problem chemicals in process effluents (primarily
phenolics)
• Confirm that all sources of problem chemicals have been
identified and controlled
• Monitor sediments regularly to confirm sediment recovery
predictions and assess the adequacy of source control
measures.
Several source control measures have already
relocation of the process effluent outfall.
been implemented, including
The maximum achievable degree of source control assumed for this FS is
95 percent, yet the model predicts that 98 percent reduction of 4-methyl-
phenol is required to maintain acceptable sediment quality over time. The
difference between these two values is not expected to be significant, given
the uncertainties and protective assumptions built into the model. Thus, it
appears possible to control sources sufficiently to maintain acceptable
long-term sediment quality following sediment remediation. This determi-
nation was made by comparing the level of source control required to
maintain acceptable sediment quality with the level of source control
estimated to be technically achievable. Source control requirements were
developed through application of the sediment recovery model for the
indicator chemical 4-methylphenol.
In situ capping was recommended as the preferred alternative for
remediation of sediments not expected to recover within 10 yr following
implementation of all known, available, and reasonable source control
measures. The selection was made following a detailed evaluation of viable
alternatives encompassing a wide range of general response actions. Because
sediment remediation will be implemented according to a performance-based
ROD, the alternative eventually implemented may differ from the currently
preferred alternative. The preferred alternative meets the objective of
providing protection for both human health and the environment by effectively
isolating contaminated sediments at in situ conditions. In situ capping
minimizes the potential for redistribution or solubilization of the organic
contaminants. The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 404 and 401 of the Clean Water Act, and other
applicable environmental requirements.
The findings of a remedial action study (Parametrix et al. 1987) for
St. Paul Waterway are in general agreement with those presented in this FS.
The boundaries of the area for sediment remediation presented in the remedial
action study are also similar to those identified in this FS. In addition,
the remedial action proposed in the remedial action study (i.e., capping) is
the same as the preferred alternative identified in this FS. Capping of
sediments was accomplished through an Ecology Consent Decree in August 1988.
8-31
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Monitoring in the sediment remedial area and at the Simpson Tacoma
Kraft outfall will be required to verify the effectiveness of remedial
measures. The area exceeding long-term cleanup goals is proposed for
inclusion in the post-remediation confirmation study to confirm proper
placement of the cap. This approach differs from the area generally
designated for the post-remediation confirmation study (i.e., the area
exceeding long-term goals with 10 yr recovery), but is considered environ-
mentally protective. If monitoring demonstrates that remedial actions have
not been effective, then additional source control or sediment remedial
measures may be required. As indicated in Table 8-4, in situ capping
provides a cost-effective means of sediment mitigation. The estimated cost
to implement this alternative is $672,000. Environmental monitoring and
other O&M costs at the disposal site have an estimated present worth of
$1,282,000 for a period of 30 yr. These costs include long-term monitoring
of the capping and sediment recovery areas to verify that source control and
natural sediment recovery have corrected the contamination problems in the
recovery areas. The total present worth cost of preferred alternative is
$1,954,000.
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
and regulations and remedial actions proposed by the potentially responsible
parties, utilize the most protective solutions practicable, and are cost-
effective.
8-32
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9.0 MIDDLE WATERWAY
Potential remedial actions are defined and evaluated in this section
for the Middle Waterway problem area. The waterway is described in Sec-
tion 9.1. This description includes a discussion of the physical features
of the waterway, the nature and extent of contamination observed during the
RI/FS field surveys, and a discussion of anticipated or proposed dredging
activities. Section 9.2 provides an overview of contaminant sources,
including site background, identification of known and potential contaminant
reservoirs, remedial activities, and current site status. The effects of
source controls on sediment remediation are discussed in Section 9.3. Areas
and volumes of sediments requiring remediation are defined in Section 9.4.
The detailed evaluation of the candidate sediment remedial alternatives
chosen for the problem area and indicator problem chemicals is provided in
Section 9.5. The preferred alternative is identified in Section 9.6. The
rationale for its selection is presented, and the relative merits and
deficiencies of the remaining alternatives are discussed. The discussion in
Section 9.7 summarizes the findings of the selection process and integrates
source control recommendations with the proposed sediment remedial alterna-
tive.
9.1 WATERWAY DESCRIPTION
The mouth of Middle Waterway is used as a navigational waterway for
commercial purposes. Water depths in Middle Waterway range from 0 ft below
MLLW at the head to 25 ft below MLLW at the mouth. An illustration of the
waterway and the locations of storm drain outfalls and nearby industries are
presented in Figure 9-1. Middle Waterway was created from the tideflats of
the Puyallup River prior to 1923 (Tetra Tech 1986c). Unlike the other
waterways in the project area, much of Middle Waterway remains intertidal
(approximately the upper half). With minor exceptions, the waterway remains
unchanged from its original configuration at approximately 3,500 ft long and
350 ft wide. The waterway sediments contain organic carbon concentrations
ranging from less than 1 to approximately 7 percent, with fine-grained
sediments ranging from 24 to 73 percent. The waterway has also been
characterized as having a low deposition rate and relatively shallow mixed
layer (Tetra Tech 1987a). The intertidal areas at the head of the waterway
exhibit increased erosion and transport associated with tidal and wave
energy activities.
9.1.1 Nature and Extent of Contamination
An examination of sediment contaminant data obtained during RI/FS
sampling efforts (Tetra Tech 1985a, 1985b, 1986c) and historical surveys has
revealed that the waterway contains elevated concentrations of both inorganic
and organic materials. No Priority 1 contaminants were identified for the
waterway. However, copper and mercury were identified as Priority 2
contaminants. The following inorganic and organic compounds exceeded their
9-1
-------
1 SIMPSON TACOMA KRAFT (STUD MILL)
2 MORSE INDUSTRIAL SUPPLY
3 PAXPORT MILLS
4 WELLWOOD
5 WASHINGTON BELT & DRIVE
6 WESTERN MACHINE
7 PACIRC YACHT BASIN
8 FIRE STATION
9 POWER SUBSTATION
10 COAST CRAFT
11 FOSS AND LAUNCH TUG
12 MARINE INDUSTRIES NORTHWEST
13 FOSS/DILLINGHAM
14 COOKS MARINE SPECIALTIES
15 PUGET SOUND PLYWOOD
16 SOUND BILT
17 D-STREET PETROLEUM FACILITIES
(MULTIPLE OWNERS)
* GROUNDWATER SEEPS
Reference: Tacoma-Pierce County Health
Department (1984.1986).
Notes: Property boundaries are approximate
based on aerial photographs and drive-
by inspections.
meters
150
Figure 9-1. Middle Waterway - Existing industries, businesses, and
discharges.
9-2
-------
corresponding AET value at only one station sampled and are therefore
considered Priority 3 contaminants: arsenic, zinc, lead, LPAH, HPAH, diter-
penoid hydrocarbons, dibenzothiophene, 4-methylphenol, methylpyrene,
dichlorobenzene, phenol, and pentachlorophenol.
The primary goal of sediment remediation in Middle Waterway is the
isolation or removal of metal contaminants. Data on the spatial gradients
of contaminants are limited as a result of sampling station distribution.
However, inorganic contaminant concentrations were found to be greatest near
the mouth of the waterway and decreased toward the head. No clear gradients
existed for most organic compounds identified. Contaminants in the waterway
demonstrate a high particle affinity. The Priority 3 contaminants arsenic,
zinc, methylpyrene, and diterpenoid hydrocarbons exceeded AET values only
when normalized to percent fine-grained sediments (Tetra Tech 1985a).
Copper and mercury were selected as indicator chemicals for Middle
Waterway. Surface sediment enrichment ratios (i.e., ratio of observed
concentration to target cleanup goal) for these two contaminants were higher
over a greater area than for the Priority 3 contaminants. These contaminants
were also selected as indicator chemicals because they are resistant to
degradation. Copper and mercury contamination have been attributed to the
same sources, primarily ship repair facilities (see Section 9.2.1). Areal
and depth distributions of mercury and copper are shown in Figures 9-2 and
9-3, respectively. Levels of contamination indicated on the figures are
normalized to cleanup goals, which are 390 mg/kg for copper and 0.59 mg/kg
for mercury. The cleanup goal for copper was determined by the AET value
for benthic infaunal abundance depression, and that for mercury was set by
the AET for the oyster larvae bioassay. Problem sediments are defined as
those with enrichment ratios greater than 1.0 (i.e., ratio of observed
concentration to cleanup goal is greater than 1.0).
Included in Figures 9-2 and 9-3 are contaminant depth profiles obtained
from two core samples. A subsurface maximum was observed for copper in core
MD-92, indicating that inputs were historically greater than are currently
observed. However, a surface maximum was observed for mercury indicating
that input has increased recently. Cores MD-91 and MD-92 were obtained from
the heavily contaminated mouth of the waterway and illustrate that contami-
nation is extensive in the shallow sediments. Remediation to a depth of
0.5 yd was assumed based on data from these cores.
9.1.2 Recent and Planned Dredging Pro.iects
The most recent dredging activity within the waterway occurred in 1982,
when Paxport Mills (No. 3 in Figure 9-1) reset a seawall and filled an area
on the east side of the waterway to provide additional storage for hogged
fuel. Approval of the project by the U.S. Army Corps of Engineers and
Ecology was contingent upon development of a salmon enhancement area near
the mouth of the waterway and adjacent to Paxport Mills. The enhancement
component was designed to replace intertidal area lost when the additional
hogged fuel storage area was built. In 1972 and again in 1978, maintenance
dredging was performed to deepen the channel near Puget Sound Plywood.
9-3
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MEAN LOWER LOW WATER
MD-92
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDIMENT SURVEYS CONDUCTED
IN 1964
SEDIMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1961)
1 SEDIMENT CONCENTRATIONS
ill EXCEED TARGET CLEANUP GOAL
MERCURY (m0/kg)
0 0.4 O.t 1.2 1.6 2.0 2.4 2.8
| i i M ' I ' ' I ' ' I ' '
01234
RATIO TO CLEANUP GOAL
0.6
0.8-
1.0-
1.2-1
MD-91
MD-92
Figure 9-2. Areal and depth distributions of mercury in sediments of
Middle Waterway, normalized to long-term cleanup goal.
9-4
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MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1961)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
0 1 2
RATIO TO CLEANUP GOAL
Figure 9-3. Areal and depth distributions of copper in sediments of
Middle Waterway, normalized to long-term cleanup goal.
9-5
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The U.S. Army Corps of Engineers has not recently received any appli-
cations for dredging permits in Middle Waterway. Neither the four major
businesses that responded to telephone queries about future dredging plans
(i.e., Paxport Mills, Foss Launch and Tug, Puget Sound Plywood, and Marine
Industries Northwest), nor the Port of Tacoma have planned for future
dredging operations in Middle Waterway (Griggs, Mr., 22 October 1987,
personal communication; Hoke, D.( 22 October 1987, personal communication;
Chamblin, D., 22 October 1987, personal communication; Slater, D., 22 October
1987, personal communication).
9.2 POTENTIAL SOURCES OF CONTAMINATION
This section provides an overview of the sources of contamination to
the sediments in Middle Waterway and a summary of available loading infor-
mation for the contaminants of concern. Table 9-1 provides a summary of
problem chemicals and source status, based on information from the RI and
earlier FS studies (Tetra Tech 1985b, 1986c; Appendix G). Elevated metal
concentrations at the mouth of the waterway with decreasing values toward
the head suggest a major source near the mouth. Maritime industries
located on the western shore are suspected, based on their proximity to the
problem sediments and their use of metal-containing products. Storm drain
inputs have also been suggested as a potential source of inorganic contami-
nants, based on a limited data set in which copper and mercury were detected
from a single drain that was sampled on three occasions. As indicated
previously, the spatial distribution of elevated concentrations of problem
organic compounds was limited and no apparent gradients existed. In
addition, data obtained during the RI/FS process suggests that it is
unlikely that there are major ongoing sources of problem organic chemicals
in the waterway (Tetra Tech 1985a). Tide and wave energy of the intertidal
environment near the head enhance sediment erosion and transport from that
area, and make the source identification process more difficult (Tetra
Tech 1987a).
9,2.1 Ship Repair Facilities
Site Background--
Shipbuilding and ship repair have been the primary land uses along the
western shoreline of Middle Waterway since the early 1900s. Although little
site-specific information is available on past operations, sandblasting,
painting, and metal-cleaning operations are the primary sources of metals
contamination at most shipyards. Prior to about 1980, ASARCO slag was used
exclusively by local ship repair facilities for sandblasting operations, and
spent sandblasting grit was commonly disposed of directly in the nearest
waterway. Typical metals concentrations in ASARCO slag have been reported as
9,000 mg/kg arsenic, 5,000 mg/kg copper, 5,000 mg/kg lead, and 18,000 mg/kg
zinc (Norton and Johnson 1984; typical mercury concentrations in slag were
not reported). After 1980, use of ASARCO slag was discontinued, replaced by
other abrasives such as Tuf-Kut. The City of Tacoma analyzed clean samples
of Tuf-Kut and reported concentrations of 20 mg/kg arsenic, 2,280 mg/kg
copper, 3 mg/kg lead, and 753 mg/kg zinc (Getchell, C., 23 December 1986b,
personal communication).
9-6
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TABLE 9-1. MIDDLE WATERWAY - SOURCE STATUS3
Chemical /Group
Mercury
Copper
Arsenic
Zinc
Lead
4-Methyl phenol
y3 Phenol
• Pentachlorophenol
Oibenzothiophene
HPAH
LPAH
Methyl pyrene
Oichlorobenzene
Diterpenoid hydrocarbons
Chemical
Priority1*
2
2
3 (MO-13)
3 (MD-19)
3 (MD-12)
3 (MO-13)
3 (MD-11)
3 (MD-11)
3 (MD-11)
3 (MD-11)
3 (MD-11)
3 (MD-12)
3 (MD-11)
3 (MD-12)
Sources Source ID Source Loading Source Status
Maritime industries Potential No Ongoing
(Cooks Marine
Specialties, Foss
Tug, Marine Indus-
tries NW)
Spillover from Potential No Ongoing
Simpson (St. Paul)
Wood products Indus- Potential No Ongoing
tries (Simpson Tacoma
Kraft, Coast Kraft)
Ubiquitous oil spills Potential No Sporadic, ongoing
Unknown No No c
c c c c
Sediment Profile Trends
Mercury has surface maxima.
Al 1 other metal s have
surface minima
Surface minimum
Variable
c
c
a Source information and sediment Information blocks apply to all chemicals in the
respective group, not to Individual chemicals only.
b For Priority 3 chemicals, the station exceeding AET Is noted in parentheses.
c Not evaluated for this study.
-------
Metals are used as antifoulant additives and constitute 2-60 percent by
volume of commercial marine paints (Muehling 1987). Mercury compounds were
often used prior to 1975, when cuprous oxide replaced mercury as the
primary antifoulant (Muehling 1987). Organotins are generally used in
conjunction with copper to increase the service life of the antifoulant
paint and are used exclusively on aluminum hulled boats because of the
corrosivity of cuprous oxide. The typical composition is 7-8 Ib cuprous
oxide and 1.5 Ib organotin per gallon of paint.
Onsite Operations--
Maritime business along the western shore of the waterway include Foss
Launch and Tug, Marine Industries Northwest, and Cooks Marine Specialties.
Foss Launch and Tug operated a ship repair facility on Middle Waterway from
about 1910 to the mid-1960s. Foss currently maintains only a customer
service and tugboat dispatch office on its property at 225 East F Street.
After ceasing ship repair activities in the mid-19601s, Foss leased most of
its property along the western edge of Middle Waterway to Peterson Boat.
Peterson Boat operated a shipbuilding and repair facility at this site
until 1978. After Peterson shut down, Foss leased the property to Marine
Industries Northwest and Cooks Marine Specialties. Marine Industries
Northwest has operated a ship repair facility at 313 East F Street since
1981. Operations at Cooks Marine Specialties, located at 223 East F Street,
include steel and aluminum work, and electrical and hydraulic repair on
marine vessels. Some shipbuilding is also conducted at the site.
Little is known about Peterson Boat. However, Dames & Moore (1982)
reported that the company had used ASARCO slag for sandblasting grit.
Sandblasting at Marine Industries Northwest is conducted onsite by a
subcontractor. After an inspection of the facility, Ecology reported that
sandblast material was entering Middle Waterway from the Marine Industries
Northwest property (Tracy 1983). There is no record of whether this problem
has been corrected. Cooks Marine Specialties currently uses Tuf-Kut
sandblasting grit, but reported that they originally used ASARCO slag
(Cook, S., 16 October 1987, personal communication). After a December 1986
inspection of the Cooks facility, Ecology reported that sandblast grit was
improperly disposed of along the shoreline adjacent to the boat ramp and in
an open area in the dock. Ecology informed Cooks owners that spent sandblast
material must be collected and disposed of at a permitted facility
(Swigert, M., 23 December 1986, personal communication). Depending on the
size of the vessel, sandblasting at Cooks is currently conducted either in a
contained area or out over the water (Cook, S., 16 October 1987, personal
communication). Smaller vessels that can be hauled out of the water are
sandblasted on the marine railway where spent grit can be collected and
removed. However, larger vessels must be sandblasted in the water. In
those cases, Cooks reports that an apron is placed alongside the boat so
that most spent grit can be captured and collected. Cooks currently stores
spent sandblast grit in sacks onsite until shipment to a landfill for
disposal.
9-8
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Recent and Planned Remedial Activities--
Ecology is currently involved in a shipyard pollution prevention
education program. The program includes workshops to inform shipyard owners
of best management practices and NPDES application procedures. Although
shipyards in the Commencement Bay area are not currently permitted under the
NPDES program, Ecology plans to write permits for all shipyard facilities.
These activities are tentatively scheduled for 1989. Permit requirements
will include provisions to prevent sandblast grit and other materials from
entering the waterways, as well as monitoring requirements for oil, grease,
turbidity, and metals. Cooks Marine Specialties was inspected by Ecology in
February 1988 and is currently going through the permitting process. Marine
Industries Northwest has not yet been inspected as part of the NPDES program.
Loading Summary--
The primary routes of contamination from shipbuilding and ship repair
activities include release of stored sandblasting material; deposition of
spent grit; and spills, overspray, and drift of paint. Quantified loading
data for these inputs from the maritime industries along Middle Waterway are
not available.
9.2.2 Storm Drains
Approximately 15 storm drains discharge into Middle Waterway
(Figure 9-4). The largest of these storm drains, MD-200, has been identified
as a probable source of many of the problem organic chemicals in Middle
Waterway (i.e., pentachlorophenol, dechlorinated benzenes, and PAH) (Tetra
Tech 1985a). MD-200 drains an area of approximately 80 ac and discharges
into the head of Middle Waterway. The drainage basin includes land on the
north and south sides of East llth Street between Portland Avenue and
St. Paul Avenue. Annual stormwater runoff from the basin is estimated at
150 ac-ft/yr (0.2 ft-Vsec) based on average annual precipitation of 37 in
(Norton and Johnson 1985a) and a runoff coefficient of 0.6 (Clark et al.
1977).
There are no NPDES-pernritted discharges in the MD-200 drainage basin.
Discharge from MD-200 consists primarily of stormwater runoff. The Tacoma-
Pierce County Health Department discovered a sanitary connection to MD-200
from Nicholson Engineering and has notified the company to reroute sewage to
the sanitary sewer system (Young, R., 19 August 1987, personal communica-
tion) .
Land use in the MD-200 drainage basin is entirely commercial and
industrial. Businesses currently operating in the basin include Simpson
Tacoma Kraft, Morse Industrial Supply, Washington Belt and Drive Systems,
Western Machinery, Ball Brass Company, Inc., Nicholson Engineering, and
Pacific Yacht Basin (see Figure 9-1). However, the wood products industry
was historically the primary industry in the basin. A lumber mill has
operated in the basin south of East llth Street since 1889. As recently as
1985, a sawmill, stud mill distributor, and log storage area were active in
the southern portion of the basin. Champion International currently owns the
9-9
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UD
I
I—•
O
LEGEND
HBB "0*0
Illllll SURFACE DRAW
19 ^- OUTFAU. AMD CHAM NUhBER
—»• n OH onec t ON
Reference. Irom Taoonie Pwroe Couny Heafth Department (19831
Figure 9-4. Surface water drainage pathways to Middle
Waterway.
-------
property around the mill, but the facility has been closed since about 1985
(Scott, E., 31 August 1987, personal communication).
Source contaminant loading calculations have been updated to include
data collected since the completion of the RI (Tetra Tech 1985a, 1986c).
Summary loading tables for the Priority 2 contaminants of concern for Middle
Waterway (i.e., copper and mercury) are provided in Appendix E. No new data
were available for any of the discharges in Middle Waterway. Storm drain
MD-200 was sampled on three occasions between April and May 1984. Analyses
for copper were conducted on two occasions, with detection once at a
concentration of 30 ug/L. The average copper concentration of average urban
runoff reported for National Urban Runoff Program study was 47 ug/L (Schueler
1987). Analyses for mercury were conducted on all three occasions. The
compound was detected once at 0.21 ug/L. Ecology sampled sediments from
MD-200 in June 1987. Of the priority pollutant metals analyzed, contaminant
concentrations were less than cleanup goals with the exception of zinc.
Zinc was detected at 410 mg/kg (enrichment ratio of 1.0) (Norton, D.,
15 April 1988, personal communication). Other analytes included a variety of
organic compounds.
9.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the effects of source control and natural
recovery processes were evaluated. This evaluation was based on the levels
of contamination in the sediment and assumptions regarding the relationship
between sources and sediment contamination. Included within the evaluation
was an estimate of the degree of source control needed to correct existing
sediment contamination problems over the long term.
9.3.1 Feasibility of Source Control
The main sources of metals to Middle Waterway are surface water runoff
from shipbuilding and repair facilities, spillage or related disposal
practices from the shipbuilding and repair facilities, and surface water
runoff from storm drains.
Maritime Industries--
Marine Industries Northwest and Cooks Marine Specialties are two active
shipyards currently associated with problem metals in the sediments of
Middle Waterway. Improper handling of paints, feedstocks, and wastes
related to sandblasting and painting operations are the primary sources or
past sources of contaminant input to the waterway. Marine Industries
Northwest and Cooks Marine Specialties are currently located on property
that was previously occupied by Foss Launch and Tug, and Peterson Boat.
9-11
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Marine Industries Northwest and Cooks Marine Specialties are currently
involved in the shipyard pollution education program initiated by Ecology.
The program is designed to inform the maritime industries of best management
practices to minimize contaminant discharges. Following the education
program, NPDES permits will be issued to the facilities to ensure that
appropriate best management practices are implemented and that effectiveness
is documented by monitoring. Among the practices to be considered for
implementation at the facilities are routine cleaning of the operations
areas, appropriate chemical storage, use of containment structures to
minimize dispersion of dust and wastes generated during operations,
constraints on bilge and ballast water discharge, and explicit limitations
on oil or hazardous material discharges to the waterway. Implementation of
best management practices is scheduled to take place over the next several
months (PTI 1988a). Given the types of contaminants, source pathways, and
available control technologies, it is estimated that implementation of all
known, available, and reasonable (i.e., feasible) technologies will reduce
source inputs by 70 percent.
Storm Drains--
Storm drain MD-200, the largest drain discharging to Middle Waterway,
has been associated with problem organic chemicals in the waterway.
However, sediment collected adjacent to MD-200 was not contaminated over
cleanup goals. The relative importance of this drain and others in
contributing to the Middle Waterway sediment problem is poorly understood at
this time because of the lack of available data on storm drain discharge
characteristics.
Available technologies for controlling surface water runoff quantity and
quality include removal of contaminant sources within the drainage basin,
onsite retention of runoff (e.g., berms, channels, grading, sumps), and
revegetation or paving to reduce erosion of waste materials (see
Section 3.2.2). In sedimentation basin or other studies, removals of over
99 percent have been achieved for lead. Removal efficiencies for other
metals (e.g., copper and zinc) are lower.
Given the contaminant types, available data regarding sources, and
available control technologies, it is estimated that implementation of all
known, available, and reasonable technologies will reduce contaminant inputs
from storm water by up to 70 percent.
Condusion--
For the waterway, the estimated feasible level of source control is
assumed to be 70 percent for both mercury and copper. These estimates
reflect the uncertainty regarding the specific sources and pathways of
contamination to the waterway, and the sediment transport mechanisms
responsible for contaminant distribution. The relative importance of storm
drain inputs is uncertain at this time. These values take into consideration
the assumed effectiveness of implementing improved material and waste
handling practices at the maritime facilities and implementation of best
management practices for both industries and the storm drains. More
9-12
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precise source control estimates require improved definition of the sources
of mercury and copper, which is beyond the scope of this document.
9.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals mercury and copper. Results are
reported in full in Tetra Tech (1987a). A summary of those results is
presented in this section.
The depositional environment in Middle Waterway was determined from
excess 210-Pb profiles collected at two stations. A sedimentation rate of
430 mg/cm2/yr (0.27 cm/yr) and a mixing depth of 10 cm were considered
representative of the mouth of the problem area where the majority of the
contaminated sediments are located. The sedimentation rate represents the
average of two values that deviate 47 percent from the mean. Two timeframes
were considered for natural recovery of sediments: a reasonable timeframe
(defined as 10 yr) and the long term. Losses due to biodegradation and
diffusion were determined to be negligible for these chemicals. The source
loading of copper is assumed to be in steady-state with sediment accumula-
tion. Sediment profiles indicate that mercury loading may be increasing.
For the purpose of this evaluation, it was assumed that the current
concentration of mercury (in freshly deposited sediments) is 2 times that
measured in the surface mixed layer. That is, if sources continue uncon-
trolled, the sediment concentration of mercury would eventually double
before reaching steady-state with loading rates. Results of the sediment
recovery evaluation are summarized in Table 9-2.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times are predicted as
71 yr for mercury and 9 yr for copper. These estimates are based on the
highest concentrations of indicator chemicals measured in the waterways.
Therefore, sediment recovery to the long-term cleanup goal for mercury in
the 10-yr timeframe is not predicted to be possible, while sediment recovery
for copper should be possible. Minimal reductions in sediment concentra-
tions of copper are predicted unless sources are controlled. Sediment
concentrations of mercury may increase if current inputs continue unabated.
Effect of Implementing Feasible Source Control--
As described in Section 9.3.1, implementation of all known, available,
and reasonable source control is expected to reduce source inputs by
70 percent for both copper and mercury. With this level of source control as
an input value, the model predicts that sediments with an enrichment of
ratio of 1.2 (i.e., copper concentrations of 468 mg/kg dry weight, mercury
concentrations of 0.70 mg/kg dry weight) will recover to the long-term
cleanup goal within 10 yr (Table 9-2). The surface area of sediments not
recovering to the cleanup goal within 10 yr is shown in Figure 9-5. For
9-13
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TABLE 9-2. MIDDLE WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
Copper Mercury
Station with Highest Concentration
Station identification MD-13 MD-13
Concentration (mg/kg dry weight) 554 3.4
Enrichment ratio3 1.4 5.8
Recovery time if sources are
eliminated (yr) 9 71
Percent source control required
to achieve 10-yr recovery NPb NPb
Percent source control required
to achieve long-term recovery 30 83
Average of Three Highest Stations
Concentration (mg/kg dry weight) 507 2.8
Enrichment ratio3 1.3 4.8
Percent source control required
to achieve long-term recovery 23 79
10-Yr Recovery
Percent source control assumed
feasible 70 70
Highest concentration recovering
in 10 yr (mg/kg dry weight) 468 0.70
Highest enrichment ratio of sediment
recovering in 10 yr 1.2 1.2
a Enrichment ratio is the ratio of observed concentration to cleanup goal
b NP = Not possible.
9-14
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AT PRESENT
IN10YR
Middle Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA (yd2)
VOLUME (yd3)
IN 10 YR
DEPTH (yd)
AREA(yd2)
VOLUME (yd3)
0.5
126,000
63.000
0.5
114,000
57,000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
COPPER (AET = 390 mg/kg)
MERCURY (AET = 0.59 mg/kg)
Figure 9-5. Sediments in Middle Waterway not meeting cleanup goafs for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
comparison, sediments currently exceeding long-term cleanup goals for
indicator chemicals are also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that 23 percent of copper and 79 percent of the
mercury inputs to the waterway must be eliminated to maintain acceptable
contaminant concentrations in freshly deposited sediments (see Table 9-2).
These estimates are based on the average of the three highest enrichment
ratios.
These values are presented for comparative purposes; the actual percent
reduction required in source loading is subject to the uncertainty inherent
in the assumptions of the predictive model. These ranges probably represent
upper limit estimates of source control requirements since the assumptions
incorporated into the model are considered to be environmentally protective.
9.3.3 Source Control Summary
Sediment recovery in a reasonable timeframe (10 yr) to long-term cleanup
goals of 390 mg/kg for copper and 0.59 mg/kg for mercury is not possible,
even with complete abatement of contaminant inputs. Consequently, sediment
remedial action will be required to mitigate the contamination problems in
the waterway.
Prior to initiating sediment remedial actions, source control measures
will be required to ensure that acceptable sediment quality is maintained
following remediation. Recommended source control measures include the
following:
• Implementation of best management practices at Marine
Industries Northwest and Cooks Marine Specialties to control
surface water runoff and material or waste spillage
• Storm drain monitoring and implementation of control measures
if unacceptable concentrations are found in storm drain
sediments or runoff.
As part of these actions, a more complete characterization of each
source will be required in order to determine the precise level of source
control required to maintain adequate sediment quality and to determine the
most feasible methods of achieving source control goals.
9.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with mercury and copper
concentrations exceeding long-term cleanup goals is approximately 63,000 yd^
(see Figure 9-5). This volume was estimated by multiplying the areal extent
of sediment exceeding the cleanup goal (126,000 yd2) by the estimated 0.5 yd
depth of contamination (see sediment contaminant profiles Figures 9-2
and 9-3). The estimated thickness of contamination is only an approximation;
few sediment profiles were collected and the vertical resolution of these
9-16
-------
profiles was poor at the depth of the contaminated horizon. For the volume
calculations, depths were slightly overestimated. This conservative
approach was taken to reflect the fact that depth to the contaminated
horizon cannot be accurately dredged, to account for dredge technique
tolerances, and to account for uncertainties in sediment quality at locations
between the sediment profile sampling stations.
The total estimated volume of sediments with copper or mercury
concentrations that is still expected to exceed long-term cleanup goals
10 yr following implementation of feasible levels of source control is
57,000 yd3. This volume was estimated by multiplying the areal extent
of sediment contamination with enrichment ratios greater than 1.2 (see
Table 9-2), an area of 114,000 yd2, by the estimated 0.5 yd depth of
contamination. These volumes are also approximations accounting for
uncertainties in sediment profile resolution and dredging tolerances. For
Middle Waterway, this is the volume of sediment that would require reme-
diation.
9.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
9.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion each alternative is evaluated to
determine its suitability for the remediation of contaminated sediments in
Middle Waterway. The objective of this evaluation is to identify the
alternative considered preferable to all others based on CERCLA/SARA
criteria of effectiveness, implementability, and cost.
The first step in this process is to assess the applicability of each
alternative to remediation of contaminated sediments in Middle Waterway.
Site-specific characteristics that must be considered in the assessment
include the nature and extent of contamination, the environmental setting,
the location of potential disposal sites, and site physical properties
including waterway usage, bathymetry, and water flow conditions. Alterna-
tives that are determined to be appropriate for the waterway can then be
evaluated based on the criteria discussed in Chapter 4.
Mercury and copper were selected as indicator chemicals to represent
the two primary sources of contamination to the waterway: ship repair
facilities and storm drains (see Table 9-1). Areal distributions for both
indicators are presented in Figure 9-5 to indicate the degree to which
contaminant groups overlap based on long-term cleanup goals.
Four alternatives have been dropped from consideration for Middle
Waterway. The need for periodic dredging to maintain channel depth at the
mouth of the waterway precludes the use of a cap in that area. The
intertidal areas of Middle Waterway have demonstrated the potential for
increased erosion and sediment transport (Tetra Tech 1987b). Therefore,
placement of a cap over this large intertidal area is not expected to be
effective. Therefore, the in situ capping alternative is dropped from
9-17
-------
further consideration. Alternatives involving treatment of organic
contaminants are inappropriate because the sediments are contaminated with
inorganic materials. Therefore, the solvent extraction, incineration, and
land treatment alternatives are not evaluated for this problem area.
It is assumed that the requirements to maintain navigational access to
the Puyallup River and Sitcum Waterway could preclude the use of a hydraulic
pipeline for nearshore disposal at the Blair Waterway disposal site.
Therefore, clamshell dredgirig has been chosen for evaluation in conjunction
with the nearshore disposal alternative.
Six candidate sediment remedial alternatives are listed below for the
cleanup of Middle Waterway:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solidification/upland disposal.
Evaluation of the no-action alternative is required by the NCR, to
provide a baseline against which other remedial alternatives can be
compared. The .institutional controls alternative, which is intended to
protect the public from direct or indirect exposure to contaminated
sediments without implementation of sediment mitigation, provides a second
baseline for comparison. The three nontreatment dredging and disposal
alternatives are all applicable to remediation of contaminated sediments in
Middle Waterway. Solidification- is primarily used to treat materials
contaminated with inorganics. This treatment technology may also be
effective in immobilizing the Priority 3 organic contaminants requiring
remediation that have demonstrated a high particle affinity in this problem
area.
9.5.2 Evaluation of Candidate Alternatives
The three primary categories of evaluation criteria are effectiveness,
implementability, and cost. A narrative matrix summarizing the assessment
of each alternative based on effectiveness and implementability is presented
in Table 9-3. A comparative evaluation of alternatives is presented in
Table 9-4 based on ratings of high, moderate, and-low in seven subcategories
of evaluation criteria. As discussed in Chapter 4, these subcategories are
short-term protectiveness; timeliness; long-term protectiveness; reduction
in toxicity, mobility, or volume; technical feasibility; institutional
feasibility; and availability. Capital and O&M costs for each alternative
are also presented in Table 9-4. Remedial costs are shown for sediments
currently exceeding long-term cleanup goal concentrations and for sediments
9-18
-------
EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
ERM PROTECTIVENESS
H
0
0
[CONTAMINANT
MIGRATION
COMMUNITY
PROTECTION
DURING1
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING'
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING *
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY^
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 9-3. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE MIDDLE WATERWAY PROBLEM AREA
NO ACTION
NA
NA
Original contamination remains.
Source Inputs continue. Ad-
verse biological impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative is ranked
sixth overall (or timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food spedes remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or Increases.
Sediment toxicity and contam-
inant mobilty are expected to
remain at current levels or
increase as a result of continued
source inputs. Contaminated
sediment volume increases as
a result of continued source
Inputs.
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during Implementation.
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during Implementation.
Source control Is implemented
and would reduce sediment con-
tamination with time, but ad-
verse impacts would persist in
the interim.
Access restrictions and mon-
itoring efforts can be imple-
mented quickly. Partial sedi-
ment recovery is achieved nat-
urally, but significant contami-
nant levels persist. This alter-
native is ranked fifth overall for
timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic dredg-
ing. Removal with dredge and
disposal with downplpe and dif-
fuser minimizes handling require-
ments. Workers wear protective
gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations. Benthic habitat Is
impacted at the disposal site.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
Disposal siting and facility con-
struction could delay implemen-
tation. This alternative is rank-
ed second overall for timeliness.
i
The long-term reliability of the
cap to prevent contaminant re-
exposure in a quiescent, sub-
aquatic environment is consi-
dered acceptable.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating contami-
nated sediments from the over-
lying biota. Protection Is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is reduced
by maintaining COM at in situ
conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM ID a barge offshore during
transport. Public access to
dredge and disposal sites Is re-
stricted. Public exposure po-
tential Is low.
Clamshell dredging of COM in-
creases exposure potential mod-
erately over hydraulic dredging.
Workers wear protective gear,
as necessary.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Nearshore intertidal habitat
Is lost Contaminated sediment
Is resuspended.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment is available. Disposal site
development should not delay
Implementation. This alternative
Is ranked first for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating CDM.
Varying physlcochemical con-
ditions in the fill may increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment. The
potential for contaminant migra-
tion into marine environment may
increase over CAD. Adjacent
fish mitigation site is sensitive
area.
The toxicity of CDM in the con-
finement zone remains at prere-
mediation levels. Altered condi-
tions resulting from dredge/dis-
posal operations may increase
mobility of metals. Contaminat-
ed sediment volumes may in-
crease due to ^suspension of
sediment.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
CDM is confined to a pipeline
during transport Public access
to dredge and disposal sites is
restricted. Exposure from CDM
spills or mishandling is possible,
but overall potential is low.
Hydraulic dredging confines
CDM to a pipeline during trans-
port. Dredge water contamina-
tion may increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment is resuspended during
dredging operations. Dredge
water can be managed ID pre-
vent release of soluble contami-
nants.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked third
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating CDM. Al-
though the potential for ground-
water contamination exists, it is
minimal. Upland disposal facili-
ties are more secure than near-
shore facilities.
Upland disposal Is secure, with
negligible potential for environ-
mental impact if property de-
signed. Potential for ground-
water contamination exists.
The toxicity of CDM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Volume of contaminated sedi-
ments is not reduced.
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Public access to dredge treat-
ment and disposal sites is re-
stricted. Exposure from CDM
spills or mishandling is possible,
but overall potential is low.
Additional CDM handling asso-
ciated with treatment increases
worker risk over dredge/disposal
options. Workers wear protec-
tive gear. Increased potential
for worker exposure due to dir-
ect handling of CDM.
Existing contaminated habitat
is destroyed. Contaminated
sediment is resuspended during
dredging operations.
Equipment development will be
required before a solidification
scheme can be implemented.
Remediation could be accom-
plished in approximately 2 years.
Extensive bench- and pilot-scale
testing are likely to be required.
This alternative is ranked fourth
overall for timeliness.
Long term reliability of solidifica-
tion treatment processes for
CDM are believed to be ade-
quate. However, data from
whicti to confirm long-term relia-
bility are limited. Upland dispos-
al facilities are structurally reli-
able.
Solid fication is a more protec-
tive solution than dredge/dis-
posa alternatives. The poten-
tial for public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Solidification Is a more protec-
tive solution than dredge/dis-
posa alternatives. The poten-
tial for public exposure is slgnl-
ficant.y reduced as a result of
contaminant immobilization.
Contaminants are physically
contained, thereby reducing
toxicity and the potential for
contaminant migration com-
pared with non-treatment alter-
natives. Metals and organics
are encapsulated.
9-19
-------
IMPLEMENTABILITY
TECHNICAL FEASIBILITY
INSTITUTIONAL FEASIBILTY
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE .
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 9-3. (CONTINUED)
NO ACTION
Implementation of this alterna-
tive is feasible and reliable.
No monitoring over and above
programs established under
other authorities Is Implemented.
There are no O & M requirements
associated with the no action
alternative.
This alternative Is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the intent of CERCUA/
SARA and NCP because of on-
going impacts.
All materials and procedures are
available.
INSTITUTIONAL
CONTROLS
Source control and institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily implemented.
Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
Some O & M is associated with
monitoring, maintenance of
warning signs, and issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels in sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
Impacts. State requirements
for source control are achieved.
Coordination with TPCHD tor
health advisories for seafood
consumption is required.
All materials and procedures are
available to implement Institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment
is reliable. Placement of dredge
and capping materials difficult,
but feasible. Inherent difficulty
in placing dredge and capping
materials at depths of 1 00 ft or
greater.
Confinement reduces monitoring
requirements in comparison to
institutional controls. Sediment
monitoring schemes can be
readily implemented.
O & M requirements are minimal.
Some O & M is associated with
monitoring for contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
Approvals for facility siting are
uncertain but assumed feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to Im-
plement alternative are readily
available. Availability of open
water CAD sites is uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
is reliable. Nearshore confine-'
mem of COM has been success-
fully accomplished.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Instal-
lation of monitoring systems is
routine aspect of facility siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facil-
ity siting are assumed feasible.
However, disposal of untreated
COM is considered less desirable
than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to Im-
plement alternative are readily
available. A potential nearshore
disposal site has been iden-
tified and Is currently available.
HYDRAULIC DREDGE7
UPLAND DISPOSAL
Hydraulic dredging equipment
is reliable. Secure upland con-
finement technology is well de-
veloped.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes and
liners. Improved confinement
enhances monitoring over CAD.
Installation of monitoring sys-
tems is routine aspect of facility
siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state.
and local agencies are feasible.
Coordination is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Solidification technologies for
treating COM on a large scale
are conceptual. Implementation
Is considered feasible, but reli-
ability is unknown. Bench-scale
testing prior to implementation is
necessary.
Monitoring requirements for so-
lidified material are low in com-
parison with dredge and dispos-
al alternatives. Monitoring can
be readily Implemented.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment. System mainten-
ance Is Intensive during imple-
mentation.
Disposal requirements are less
stringent for treated dredge ma-
terial enhancing approval feasi-
bility. However, bench scale
testing Is required to demon-
strate effectiveness of solidifi-
cation.
WISHA/OSHA worker protection
required. Alternative complies
with U.S. ERA'S policies for on-
site disposal and permanent re-
duction in contaminant mobility.
May require that shoreline man-
agement aspects be addressed.
Disposal site availability is un-
certain but feasible. Solidifica-
tion equipment and methods for
large scale COM disposal are
currently unavailable.
9-20
-------
TABLE 9-4. EVALUATION SUMMARY FOR MIDDLE WATERWAY
ro
Short -Term Protect iveness
Timeliness
Long-Term Protect iveness
Reduction in Toxicity,
Mobility, or Volume
Technical Feasibility
Institutional Feasibility
Availability
Long- Term Cleanup
Goal Costs*
Capital
O&M
Total
Long- Term Cleanup
Goal with 10-yr
Recovery Costs"
Capital
O&M
Total
No Action
Low
Low
Low
Low
High
Low
High
—
--
—
—
—
—
t
Institutional
Control s
Low
Low
Low
Low
High
Low
High
6
1.274
1.280
6
1,183
1,189
Clamshell/
CAD
High
Moderate
High
Low
Moderate
Moderate
Moderate
519
195
714
461
179
640
Clamshell/
Nearshore
Di sposal
Moderate
High
Moderate
Low
High
Moderate
High
1.566
180
1.746
1,409
165
1,574
Hydraulic/
Upland
Di sposal
High
Moderate
Moderate
Low
High
Moderate
Moderate
2.754
224
2,978
2,481
205
2.686
Clamshell/
Solidify/
Upland
Di sposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
4.199
218
4.417
3,791
199
3,990
All costs are in $1,000.
-------
that would still exceed the cleanup goal concentrations 10 yr after
implementing all known, available, and reasonable source controls and
allowing natural sediment recovery to occur (i.e., 10-yr recover costs).
Short-Term Protect!veness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
biological and potential public health impacts continue with the contaminated
sediments remaining in place. Source control measures initiated as part of
the institutional controls would tend to reduce sediment contamination with
time but adverse impacts would persist in the interim. It is predicted that
even with complete source elimination, reduction in sediment concentrations
to acceptable levels could require over 70 yr for mercury (see Table 9-2).
The alternative requiring clamshell dredging and nearshore disposal is
rated moderate under this criterion because nearshore habitat would be lost
in siting the disposal facility. For example, use of the Blair Waterway
Slip 1 site would result in the loss of up to 16 ac of nearshore marine
habitat. While the loss of habitat due to nearshore site development in
Commencement Bay may be mitigated by requiring habitat enhancement in a
nearby area, the availability of sites with potential for habitat enhancement
is limited. The clamshell dredging/solidification/upland disposal alterna-
tive is also rated moderate because of the increased potential for worker
exposures due to solidification-related handling of contaminated dredged
material. In spite of the increased exposure potential, the moderate rating
is appropriate because adequate worker health and safety controls are
available.
The clamshell dredging/confined aquatic disposal and hydraulic
dredging/upland disposal alternatives are rated high for short-term
protectiveness because worker and public exposure potentials are minimized.
Hydraulic dredging confines contaminated dredged material to a pipeline
system throughout implementation, thereby reducing exposure potentials.
Although upland disposal requires use of an upland area, the tradeoff is
considered to be acceptable because the habitats that are selected for
disposal are generally of low sensitivity (U.S. Army Corps of Engineers
1988). Similarly, development of an open-water confined aquatic disposal
site entails short-term impacts to the benthic community at the site.
However, re-establishment of the area is expected to occur rapidly following
capping. The placement of contaminated dredged material in the subaquatic
environment with a split-hulled barge minimizes handling requirements. The
potential also exists for adverse water quality impacts due to dredging of
contaminated material. However, Middle Waterway sediments are characterized
by predominantly inorganic materials with high particle affinity and little
potential for partitioning to the water column.
Timeliness--
Because an extensive amount of time is necessary for sediments to
recover naturally from mercury contamination, both the no-action and
institutional controls alternatives are rated low. Recovery times for all
9-22
-------
sources of the indicator compounds would range from 9 yr to 71 yr (see
Section 9.3.2).
Moderate ratings have been applied to the clamshell dredging/confined
aquatic disposal, hydraulic dredging/upland disposal, and clamshell
dredging/solidification/upland disposal options. For dredging options that
involve siting of upland or open-water confined disposal facilities,
approvals and construction are estimated to require a minimum of 1-2 yr.
Solidification may require extra time for bench-scale testing and equipment
development or modification, although facility siting and technology
development could be conducted concurrently.
The clamshell dredging/nearshore disposal option is rated high for
timeliness because this alternative can be implemented immediately with
available technologies, expertise, and facilities.
Long-Term Protectiveness--
The comparative evaluation for long-term protectiveness resulted in
low ratings for the no-action and institutional controls alternatives
because the timeframe for natural recovery is long. For the institutional
controls alternative, the potential for exposure to contaminated sediments
remains, albeit at declining levels following implementation of source
reductions. The uncertainty associated with identifying the source of
mercury contamination further compromises the protectiveness rating for
institutional controls. The observed adverse biological impacts would also
continue.
Moderate ratings were assigned for clamshell dredging/nearshore
disposal and hydraulic dredging/upland disposal alternatives because of
potential physicochemical changes resulting from the placement of con-
taminated dredged material in these disposal facilities. These changes,
primarily from new redox conditions, would tend to increase the migration
potential of the contaminants. However, contaminated dredged material
testing should provide the necessary data on the magnitude of these impacts.
For the nearshore disposal option, these impacts could be reduced by
ensuring that Middle Waterway dredged materials are placed below the
saturated zone in the confinement facility. Although the structural
reliability of the nearshore facilities is regarded as good, the nearshore
environment is dynamic in nature as a result of wave action and tidal
influences. The nearshore disposal alternative also introduces the potential
for impacts to the adjacent fish mitigation area in the outer Blair Waterway
slip. Proper site development and monitoring should minimize the potential
for impacting this area. Even though an upland disposal facility is
generally regarded as a more secure option because of improved engineering
controls during construction, the potential for impacts on area groundwater
resources partially offsets the improvement, in long-term security.
The confined aquatic disposal option is rated high for this criterion
because placement of material in a confined, quiescent, subaquatic environ-
ment provides a high degree of isolation, with little potential for exposure
to sensitive environment. Once the cap is in place, maintaining its
9-23
-------
integrity against erosion and bioturbation will be sufficient to retain
sediment-bound contaminants (Phillips et al. 1985). Maintaining the reduced
conditions in the subaquatic environment also aids in minimizing the
migration potential of inorganic contaminants.
The clamshell dredging/solidification/upland disposal alternative is
also rated high for long-term protectiveness. The high degree of immobili-
zation provided by solidification of primarily inorganic contaminants
substantially increases the long-term protectiveness of this alternative
over dredge and disposal alternatives. In addition, the lower priority
organic contaminants that have been identified exhibit a high degree of
particle affinity, enhancing immobilization due to particle encapsulation.
Reduction in Toxicity, Mobility, or Volume--
Low ratings have been assigned to all alternatives under this criterion,
except the clamshell dredging/solidification/upland disposal option which
was rated high. None of the other five alternatives involves treatment for
contaminated sediments. Although the confined aquatic, upland, and nearshore
disposal alternatives isolate contaminated dredged material from the
surrounding environment, the chemistry of the material remains unaltered.
For nearshore (depending on placement in the confinement facility) and
upland disposal alternatives, the mobilization potential for untreated
contaminated dredged material may actually increase with changes in redox
potentials. Without treatment, the toxicity of contaminated sediments
remains at preremediation levels. Contaminated sediment volumes are not
reduced, and may actually increase in the short-term with hydraulic dredging
options because material would be suspended in an aqueous slurry.
Solidification of contaminated dredged material prior to disposal
effectively encapsulates inorganic contaminants, thereby reducing mobiliza-
tion potential permanently and significantly. Through isolation in the
solidified matrix, this process also reduces the effective toxicity of
contaminants as compared with nontreatment alternatives. Because the
available data suggest that the organic contaminants present have a high
particle affinity, the process may also be relatively effective in encapsula-
ting these materials. Elutriate tests during bench-scale testing of
solidified contaminated dredged material will provide sufficient data to
assess immobilization of contaminants.
Technical Feasibility--
The alternative involving solidification is assigned a moderate rating
for technical feasibility because of the need for bench-scale testing prior
to implementation. In addition, solidification technologies for the
treatment of contaminated dredged material on a large scale are conceptual
at this point, although the method appears to be feasible (Cullinane, J.,
18 November 1987, personal communication). The difficulty inherent in
placing dredge and capping materials at depths of over 100 ft requires that
a moderate rating be assigned to the confined aquatic disposal alternative,
as well.
9-24
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High ratings are warranted for all other alternatives because the
equipment, technologies, and expertise required for implementation have been
developed and are readily accessible. The technologies constituting these
alternatives have been demonstrated to be reliable and effective elsewhere
for similar operations.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods are applied for all alternatives. The
intensity of the monitoring effort, which varies with uncertainty about
long-term reliability, does not influence the feasibility of implementation.
Institutional Feasibility—
The no-action and institutional controls alternatives .have been
assigned low ratings for institutional feasibility because compliance with
CERCLA/SARA mandates would not be achieved. Requirements for long-term
protection of public health and the environment would not be met by either
alternative.
Moderate ratings are assigned to the remaining four alternatives
because of potential difficulty in obtaining agency approvals for disposal
sites or implementation of treatment technologies.
Although several potential confined aquatic and upland disposal sites
have been identified in the project area, significant uncertainty remains
with the actual construction and development of the sites. The Blair
Waterway nearshore facility is considered to be available. Although
excavation and disposal of untreated, contaminated sediment is discouraged
under Section 121 of SARA, properly implemented confinement should satisfy
the primary requirement for public health and environmental protectiveness.
Agency approvals are assumed to be contingent upon a bench-scale demon-
stration of the effectiveness of each alternative in meeting established
performance goals (e.g., treatability of dredge water and immobilization of
contaminants through solidification).
Availability--
Candidate sediment remedial alternatives that can be implemented
using existing equipment, expertise, and disposal or treatment facilities
are rated high for availability. The no-action and institutional controls
alternatives can be implemented immediately, and equipment and siting
availability are not obstacles to implementation. The clamshell dredging/
nearshore disposal alternative is rated high because a disposal site is
considered to be available at this time.
Remedial alternatives involving dredging with confined aquatic or upland
disposal are rated moderate because of the uncertainty associated with
disposal site availability. Candidate alternatives were developed by
assuming that open-water confined aquatic and upland sites will be available.
However, no sites have been identified for use and no sites are currently
9-25
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under construction. Depending on the final characterization of sediments,
upland disposal in an existing municipal or demolition landfill may also be
feasible. However, no sites are currently available for use in the project
area or adjacent vicinity. A moderate rating has also been assigned to the
dredging/solidification/upland disposal alternative because of the same
uncertainties regarding disposal site availability. However, leachate tests
conducted as a part of the bench-scale treatability and performance evalua-
tion for the solidification process should be adequate to determine whether
the treated product is acceptable for placement in a standard solid waste
management facility.
Cost--
The comparative evaluation of costs (see Table 9-4) reveals a trend of
increasing capital cost with increasing complexity (i.e., from no action to
the treatment option). This increase reflects the need to site and construct
disposal facilities, develop treatment technologies, and implement alter-
natives requiring extensive contaminated dredged material or dredge water
handling. Costs for hydraulic dredging/upland disposal are significantly
higher than those for clamshell dredging/nearshore disposal, primarily
because of underdrain and bottom liner installation, additional dredge water
clarification, and use of two pipeline boosters to facilitate contaminated
dredged material transport to the upland site. The cost of conducting the
solidification alternative increases as a result of material costs for the
process, and associated labor costs for material handling and transport.
Clarification and dredge water management costs are also incurred for this
option.
A major component of O&M costs is the monitoring requirements associated
with each alternative. The highest monitoring costs are associated with
alternatives involving the greatest degree of uncertainty for long-term
protectiveness (e.g., institutional controls), or where extensive monitoring
programs are required to ensure long-term performance (e.g., confined
aquatic disposal). Costs for monitoring of the confined aquatic disposal
facility are significantly higher because of the need to collect sediment
core samples at multiple stations, with each core being sectioned to provide
an appropriate degree of depth resolution. Nearshore and upland disposal
options, on the other hand, use monitoring well networks requiring only the
collection of a single groundwater sample from each well to assess con-
taminant migration.
It is also assumed that the monitoring program will include analyses
for all contaminants of concern (i.e., those exceeding long-term cleanup
goals) in the waterway. This approach is conservative and could be modified
to reflect use of key chemicals to track performance. Monitoring costs
associated with the solidification alternative are significantly lower
because the process results in lower contaminant migration potential.
9.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the six sediment remedial alter-
natives proposed for Middle Waterway, clamshell dredging with nearshore
9-26
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disposal has been recommended as the preferred alternative for sediment
remediation. Because sediment remediation will be implemented according to
a performance-based ROD, the specific technologies identified in this
alternative (i.e., clamshell dredging, nearshore disposal) may not be the
technologies eventually used to conduct the cleanup. New and possibly more
effective technologies available at the time remedial activities are
initiated may replace the alternative that is currently preferred. However,
any new technologies must meet or exceed the performance criteria (e.g.,
attainment of specific cleanup criteria) specified in the ROD. The
nearshore disposal alternative is currently preferred for the following
reasons:
• The alternative protects public health and the environment by
effectively isolating contaminated sediments in an engineered
disposal facility
• The alternative is consistent with existing plans to fill the
Blair Waterway Slip 1 proposed nearshore fill site
• The nature of the contaminants is such that placement below
the saturated zone should minimize migration potential
• The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 401 and 404 of the Clean Water Act,
and other applicable environmental requirements
• Performance monitoring can be accomplished effectively and
implemented readily
• The estimated 57,000-yd-^ volume of contaminated sediments is
compatible with the capacity of the proposed nearshore
facility
• Although the cost of this alternative is approximately
$1 million less than that of the upland disposal alternative,
it is expected to provide an equivalent degree of public
health and environmental protection
• Although this option is approximately $1 million more than
the confined aquatic disposal option, largely due to the cost
of acquiring nearshore property in the project area, the
additional expenditure is justified since the action can be
implemented more quickly in an available facility that
offers appropriate confinement conditions for the contaminants
of concern.
The nearshore alternative is rated high for timeliness, technical
feasibility, and availability because available equipment, resources, and
disposal facilities are used. The alternative can be implemented quickly
with reliable equipment that has proven effective in past similar operations.
This alternative is also consistent with the Port of Tacoma's plans to fill
Blair Waterway Slip 1 to create additional land space. The volume of
9-27
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contaminated dredged material requiring remediation is compatible with the
capacity of the potential nearshore disposal facility.
The alternative is rated moderate for short-term protectiveness because
of the loss of intertidal habitat. This disadvantage can be offset through
incorporation of a habitat replacement project in the remedial process. The
goal of habitat enhancement is addressed in part by removing contaminated
sediments from the waterway. One-to-one replacement of excavated intertidal
sediments with clean fill material has been incorporated into the cost
calculations. The nature and placement of the clean intertidal materials
can be designed to maximize habitat quality and recolonization potential.
The alternative is also rated moderate for long-term protectiveness
because contaminated sediments are placed in an environment subject to wave
and tidal influences, and because of the proximity of the adjacent fish
mitigation area in the outer slip. Contaminants in Middle Waterway have
demonstrated relatively high particle affinities (Tetra Tech 1987c), which
would serve to improve long-term containment reliability. Hart-Crowser &
Associates (1985) concluded that monitoring of contaminant mobility from
nearshore disposal sites could be effectively accomplished with monitoring
wells in containment berms for early detection of contaminant movement.
Monitoring and corrective measures (in the event of system failures) would
be more easily implemented in the nearshore facility than in a confined
aquatic disposal site (which also received similar ratings). Long-term
protectiveness could be enhanced with the placement of slurry walls within
the berm (Phillips et al. 1985); however this measure has not been included
in the cost estimate. As indicated in Table 9-4, the nearshore disposal
alternative also provides a cost-effective means of sediment mitigation.
This alternative is approximately $1 million less than the hydraulic
dredging/upland disposal alternative, and less than 50 percent of the cost
for the treatment option.
Although some sediment resuspension is inherent in dredging operations,
silt curtains and other available engineering controls would be expected to
minimize adverse impacts associated with contaminated dredged material
redistribution. Potential impacts on water quality can be predicted by
using data from bench-scale tests to estimate contaminant partitioning to
the water column. Because this alternative can be implemented over a
relatively short timeframe, seasonal restrictions on dredging operations to
protect migrating anadromous fish are not expected to pose a problem. For
dredging contaminated sediments in the shallow and intertidal areas of the
waterway, tidal stage will need to be accommodated. Dredging activities
within this area are consistent with the Tacoma Shoreline Management Plan
and Sections 404 and 401 of the Clean Water Act. Close coordination with
appropriate federal, state, and local regulatory personnel will be required
prior to undertaking remedial actions.
Of the remaining alternatives, solidification of the inorganic contami-
nants prominent in Middle Waterway is also feasible. Solidification and
upland disposal was not selected as the preferred alternative because of
uncertainties regarding availability of a disposal site, the reliability
and effectiveness of solidifying marine sediments, and high costs. These
9-28
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uncertainties and high costs are partially offset by the potential added
degree of long-term protectiveness afforded by treating contaminated dredged
material. The costs of implementing the treatment alternative are
approximately $2.4 million more than the nearshore disposal alternative.
With maximum enrichment ratios of 5.8 for mercury (mercury concentration of
3.4 mg/kg) and 2.2 for copper (subsurface concentration at MD-92 of
870 mg/kg), this additional expenditure does not appear to be warranted. If
this option were considered, bench-scale testing of Middle Waterway
contaminated dredged material would be warranted to more accurately define
process effectiveness and treatment costs.
Hydraulic dredging with upland disposal was not selected because of
uncertain disposal site availability and the bias against landfilling of
untreated contaminated dredged material. Although this alternative is
feasible from both a technical and institutional standpoint, the risk of
system failures in the upland environment (e.g., groundwater risks) com-
promises its desirability.
The confined aquatic disposal alternative was not selected because the
volume of material is compatible with the available nearshore disposal site.
The nearshore alternative can be implemented more quickly, while providing
a degree of protection that is appropriate for the contaminants of concern.
Assuming that a confined aquatic disposal site becomes available, this
option would also serve to effectively isolate dredged material. However,
the close proximity of the Blair Waterway nearshore facility and availability
of capacity below the water line where near in situ physicochemical
conditions could be maintained for inorganic contaminants make nearshore
disposal preferable. The close proximity of the Blair Waterway disposal
site to the Middle Waterway problem area (approximately 1.5 mi) may also
warrant review of the use of a hydraulic dredge for excavation and disposal
during remedial design studies. Clamshell dredging and barge transport were
selected in this case because of logistical uncertainties regarding the need
to cross navigational waterways and the Puyallup River.
No-action and institutional controls alternatives are ranked high for
technical feasibility, availability, and capital expenditures. However, the
failure to mitigate environmental and potential public impacts far outweighs
these advantages.
9.7 CONCLUSIONS
Middle Waterway was identified as a problem area because of the
elevated concentrations of both inorganic and organic contaminants in
sediments. Mercury and copper were selected as indicator chemicals to
assess source control requirements, evaluate sediment recovery, and estimated
the area and volume to be remediated. In this problem area, sediments with
concentrations currently exceeding long-term cleanup goals cover an area of
approximately 126,000 yd2, and a volume of 63,000 yd3. Of the total sediment
area currently exceeding cleanup goals, 12,000 yd2 is predicted to recover
within 10 yr following implementation of all known, available, and reasonable
source control measures, thereby reducing the contaminated sediment volume
9-29
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by 6,000 yd3. The total volume of sediment requiring remediation is,
therefore, reduced to 57,000 yd^.
The primary identified and potential sources of problem chemicals to
Middle Waterway include the following:
• Marine Industries Northwest
• Cooks Marine Specialties.
Source control measures required to correct these problems and ensure
the long-term success of sediment cleanup in the problem area include the
following actions:
• Implement best management practices at Marine Industries
Northwest and Cooks Marine Specialties
• Confirm that all significant sources of problem chemicals
have been identified and controlled
• Routinely monitor sediment to confirm sediment recovery
predictions and assess the adequacy of source control
measures.
In general, it should be possible to control sources sufficiently to
maintain acceptable long-term sediment quality. This determination was made
by comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. However, the level of source control required for mercury was
estimated to be approximately 79 percent, compared to a technically feasible
level of approximately 70 percent. Additional evaluations to refine these
estimates will be required as part of the source control measures described
above. Source control requirements were developed through application of the
sediment recovery model for the indicator chemicals copper and mercury. The
assumptions used in determining source control requirements were environ-
mentally protective. It is anticipated that more detailed loading data will
demonstrate that sources can be controlled to the extent necessary to
maintain acceptable sediment quality. If the potentially responsible
parties demonstrate that implementation of all known, available, and
reasonable control technologies will not provide sufficient reduction in
contaminant loadings, then the area requiring sediment remediation may be re-
evaluated.
Clamshell dredging with nearshore disposal was recommended as the
preferred alternative for the remediation of sediments not expected to
recover within 10 yr following implementation of all known, available, and
reasonable source control measures. The selection was made following a
detailed evaluation of viable alternatives encompassing a wide range of
general response actions. Because sediment remediation will be implemented
according to a performance-based ROD, the alternative eventually implemented
may differ from the currently preferred alternative. The preferred
alternative meets the objective of providing protection for both human
9-30
-------
health and the environment by effectively isolating contaminated sediments
in an engineered disposal facility where performance monitoring can be
readily implemented. Disposal sites for nearshore confinement are available
at this time. Use of material from Middle Waterway in a nearshore disposal
facility is compatible with the Port of Tacoma's industrial development
plans, minimizing the impacts of using another facility. Concerns regarding
potential contaminant migration to an adjacent fish mitigation area will be
addressed through the placement of contaminated material in a saturated
environment and the ongoing monitoring program to detect potential problems
in sufficient time to implement corrective measures. Nearshore disposal has
been demonstrated to be effective in isolating contaminated sediments
(U.S. Army Corps of Engineers 1988). The alternative is consistent with the
Tacoma Shoreline Management Plan, Sections 404 and 401 of the Clean Water
Act, and other applicable environmental requirements.
As indicated in Table 9-4, clamshell dredging with nearshore disposal
provides a cost-effective means of sediment mitigation. The estimated cost
to implement this alternative is $1,409,000. Environmental monitoring and
other O&M costs at the disposal site have a present worth of $165,000 for a
period of 30 yr. These costs include long-term monitoring of sediment
recovery areas to verify that source control and natural sediment recovery
have corrected the contamination problems in the recovery areas. The total
present worth cost of the preferred alternative is $1,574,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control.
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures.
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
9-31
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The proposed remedial measures are consistent with other environmental laws
and regulations, utilize the most protective solutions practicable, and are
cost-effective.
9-32
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10.0 HEAD OF CITY WATERWAY
Potential remedial actions are defined and evaluated in this section
for the head of City Waterway problem area. The waterway is described in
Section 10.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 10.2 provides an overview of contaminant
sources, including site background, identification of known and potential
contaminant reservoirs, remedial activities, and current site status. The
effects of source control measures on sediment contaminant concentrations
are discussed in Section 10.3. Areas and volumes of sediments requiring
remediation are discussed in Section 10.4. The detailed evaluation of the
candidate sediment remedial alternatives chosen for the problem area and
indicator problem chemicals is provided in Section 10.5. The preferred
alternative is identified in Section 10.6. The rationale for its selection
is presented, and the relative merits and deficiencies of the remaining
alternatives are discussed. The discussion in Section 10.7 summarizes the
findings of the selection process and integrates required source control
with the preferred remedial alternative.
10.1 WATERWAY DESCRIPTION
The problem area designated as the head of City Waterway extends from
the head of the waterway to the llth Street Bridge, approximately 3,500 ft
from the mouth. An illustration of the waterway and nearby industries is
presented in Figure 10-1. This portion of the waterway is approximately
4,500 ft in length and varies in width between 460 and 600 ft, with very
irregular shorelines (Tetra Tech 1985a). City Waterway is a designated
navigational channel. Subbottom profiling in the head of City Waterway
indicated mid-channel depths ranging from less than 10 ft below MLLW in the
southern end to approximately 30 ft below MLLW at the llth Street Bridge
(Raven Systems and Research 1984).
Significant sediment accumulation occurs in City Waterway primarily as
a result of storm sewer discharges. Sediment accumulation is estimated to
be greater than 10 ft deep at the head of the waterway and decreases to
approximately 3 ft underneath the llth Street Bridge. Sediments within City
Waterway are typically 64 percent fine-grained material, with an average clay
content of 18 percent. These sediments are described as anoxic with a very
high organic content (nearly 9 percent). Between 1905 and 1948, the waterway
was dredged every 3 to 12 yr. City Waterway has not been dredged by the
U.S. Army Corps of Engineers since 1948.
10.1.1 Nature and Extent of Contamination
An examination of sediment contamination data obtained during both the
RI/FS sampling efforts (Tetra Tech 1985a, 1985b, 1986c) and historical
10-1
-------
1 PUGET SOUND PLYWOOD
2 -D- STREET PETROLEUM FACILITIES
3 -D" STREET PETROLEUM FACILITIES (MULTIPLE OWNERS',
4 COAST CRAFT
5 PICK COUNDRY
6 GERRISH BEARING
7 OLYMPIC CHEMICAL
8 GLOBE MACHINE
9 PUGET SOUND HEAT TREATING
10 MARINE IRON WORKS
11 WOOOWORTH S COMPANY
12 WESTERN DRY KILN
13 WESTERN STEEL FABRICATORS
14 OLD ST. REGIS DOOR MILL (CLOSED)
15 KLEEN BLAST
16 NORTHWEST CONTAINER
17 RAINIER PLYWOOD
18 MARTINAC SHIPBUILDING
19 CHEVRON
20 HYGRADE FOODS
21 TAR PITS SITE (MULTIPLE OWNERS)
22 WEST COAST GROCERY
23 PACIFIC STORAGE
24 MARINA FACILITIES
25 EMERALD PRODUCTS
26 PICKERING INDUSTRIES
27 UNION PACIFIC & BURLINGTON NORTHERN RAILROADS
28 PICKS COVE BOAT SALES AND REPAIRS
PCKS COVE MARINA
29 AMERCAN PLATING
30 INDUSTRIAL RUBBER SUPPLY
31 TOTEM MARINE
32 COAST IRON MFG.
33 MSA SALTWATER BOATS
34 CUSTOM MACHINE MFG.
35 WESTERN FISH
36 OLD TACOMA LIGHT
37 COLONIAL FRUIT & PRODUCE
38 J.D.ENGLISH STEEL CO.
39 JOHNNY'S SEAFOOD
40 CASCADE DRYWALL
41 SCOFIELD, TRU-MIX, N. PACIFIC PLYWOOD (CLOSED)
42 PACIFIC COAST OIL
43 CITY WATERWAY MARINA
44 J.H. GALBRAITH CO.
45 HARMON FURNITURE
46 TACOMA SPUR SITE
Reference: Tacoma-Pierce County Health
Department (1984,1966).
Notes: Property boundaries are approximate
baaed on aerial photographs and drive-
by inspections.
46
Figure 10-1. Head of City Waterway - Existing industries and
businesses.
10-2
-------
surveys revealed that the waterway contains concentrations of both organic
and inorganic materials that are harmful to benthic organisms. The contami-
nants that were observed had a high particle affinity (Tetra Tech 1987c).
Priority 1 contaminants include total organic carbon, zinc, lead, and
mercury. Priority 2 contaminants include grease and oil, LPAH, HPAH,
phenol, cadmium, nickel, 2-methylphenol, 4-methy1 phenol, bis(2-ethylhexyl)-
phthalate, and butyl benzyl phthalate. The following organic contaminants
exceeding their AET value at only one station sampled and are therefore
considered Priority 3 contaminants: 1-4-dichlorobenzene, N-nitrosodiphenyl-
amine, aniline, and benzyl alcohol.
Concentrations of total organic carbon and grease and oil were greater
in the surface sediments of City Waterway than at any other location in the
entire Commencement Bay N/T study area. Concentrations were highest at the
head of the waterway, indicating that adjacent storm drains (CN-237 and
CS-237) are a significant source. Untreated sewage and food waste products
were historically discharged to the waterway from these storm drains,
contributing major quantities of waste material to the sediments. The
concentration profile of total organic carbon collected at the head of City
Waterway displayed fairly constant levels to a depth of 200 cm, indicating
that elimination of sewage discharges to the storm drain has not resulted in
significant decreases in the surface sediment concentrations. Total organic
carbon concentrations in surficial sediments decreased from the head of the
waterway to the mouth (Tetra Tech 1985a).
HPAH was selected as an indicator chemical at the head of City Waterway
to represent hydrocarbon contamination attributed to multiple potential
sources (see Section 10.2). Areal and depth distributions of HPAH are
illustrated in Figure 10-2. Concentrations of HPAH were below the long-term
cleanup goal of 17,000 ug/kg at all stations except one. The sediment core
profile shown in Figure 10-2 indicates that HPAH was present to depths of
about 1 yd.
Zinc was identified as an indicator chemical for the head of City
Waterway in the Commencement Bay RI. However, the AET used to determine
enrichment ratios for zinc increased substantially (i.e., from 260 to
410 mg/kg) when the AET values were revised (PTI 1988). The increase in the
AET value resulted in fewer stations exceeding long-term goals, hence the
usefulness of zinc as an indicator of chemical contamination diminished.
Cadmium is used as a replacement for zinc. The cadmium AET decreased (i.e.,
from 5.9 to 5.1 mg/kg) when the AET values were revised. Correspondingly,
over 50 percent of the stations that have data for cadmium exceeded long-term
goals. The distribution of cadmium in the head of City Waterway suggests
that it is an appropriate indicator of chemical contamination.
Surface sediment concentrations of the metals zinc, copper, and lead
were observed to increase toward the head of City Waterway suggesting a
source near that area. The metals mercury, cadmium, and nickel did not
exhibit a similar spatial distribution (Tetra Tech 1985a, 1986c). Lead was
selected as an inorganic indicator contaminant to represent sources near the
head of the waterway. Mercury and cadmium were selected to represent
inorganic contaminants with more erratic distribution. Areal and depth
10-3
-------
HPAH (tig/kg)
0 2.000 4.000 6.000
0 0.1 02 0.3 0.4
RATIO TO CLEANUP GOAL
0.2
0.4
a
u
a
0.8-
1.0-
1.2-1
CI-91
MEAN LOWER LOW WATER
FEAS4BLITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDMENT SURVEYS CONDUCTED
IN 1984
SEDMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
CI-91
Figurel 0-2. Area! and depth distributions of HPAH in sediments at the
head of City Waterway, normalized to long-term cleanup
goal.
10-4
-------
distributions of cadmium are illustrated in Figure 10-3. Cadmium concentra-
tions in excess of the 5.1 rag/kg long-term cleanup goal were greatest in the
lower and central portions of the problem area. The sediment core sample
collected near the head of the waterway shows a subsurface maximum for
cadmium, indicating that the accumulation of cadmium is due to historic
sources. Cadmium concentrations exceeding long-term cleanup goals were
observed at depths exceeding 2 yd. Areal and depth distributions of lead
are illustrated in Figure 10-4. Elevated concentrations of lead were
observed throughout the problem area, with surficial sediment concentra-
tions exceeding the 450 mg/kg long-term cleanup goal. The sediment core
profile collected near the head of the waterway revealed fairly constant
concentrations of lead exceeding cleanup goals to a depth of 2 yd. Areal
and depth distributions of mercury are shown in Figure 10-5. Surficial
sediment concentrations of mercury were highest in the central portion of
the problem area with patchy areas exceeding the long-term cleanup goal of
0.59 mg/kg observed both in the center of the problem area and near the
llth Street Bridge. The sediment core profile collected near the head of the
waterway revealed a surface minimum, with elevated subsurface values to a
depth of 2 yd.
Few sources have been identified for the numerous other high, priority
problem chemicals found in sediments at the head of City Waterway. The
sediment profile of 2-methylphenol displayed a surface concentration
maximum, indicating that inputs may be increasing. However, the sediment
profile for 4-methylphenol displayed a surface concentration minimum,
suggesting recent decreases in input. Other problem organic compounds
exhibited limited spatial distribution, and elevations over AET were not
excessive (Tetra Tech 1987c).
10.1.2 Recent and Planned Dredging Pro.iects
Two enterprises at the head of City Waterway have requested dredging
permits from the U.S. Army Corps of Engineers: the Port of Tacoma and City
Marina, Inc. The Port of Tacoma recently constructed a pier and access ramp,
and installed floats on property adjacent to the Dock Street businesses;
however, no dredging was actually conducted as part of this work. City
Marina plans to install floats, drive piles, and place riprap and backfill
adjacent to their property at the head of the waterway.
Businesses and industries that responded when queried about future
dredging plans are itemized below:
• City Waterway Marina dredged less than 40 yd^ in summer 1987,
(Norsen, 2 November 1987, personal communication). The
company had a U.S. Army Corps of Engineers permit to build an
over-water restaurant. Although this construction could
involve some dredging, it is not likely that any significant
dredging would be involved.
10-5
-------
CADMIUM (mg/ka)
0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.010.011.0
0.1-
0.2-
0.4-
0.6-
0.8-
1.0-
|1.2-
f 1.4-
S1.6H
1.8-
2.0-
2.2-
2.4-
2.6-
2.8-
RATKD TO CLEANUP GOAL
CI-91
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEGMENT SURVEYS CONDUCTED
IN 1964
SEDWENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1961)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
CI-91
Figure 10-3. Areal and depth distributions of cadmium in sediments at the
head of City Waterway, normalized to long-term cleanup
goal.
10-6
-------
LEAD (mg/kg)
0 SOO 1,000
0 -
0.2-
0.4-
0.6-
0.8-
1'°-
1.2-
1.4-
1.6-
1.8
2.0-
2.2
2.4
1.500
1 2 3
RATIO TO CLEANUP GOAL
CI-91
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEWMENT
PROFILE SURVEYS (1966)
SEGMENT SURVEYS CONDUCTED
IN 1964
SEDMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1981)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP OOAi.
CI-91
Figure 10-4. Area! and depth distributions of lead in sediments at the
head of City Waterway, normalized to long-term cleanup
goal.
10-7
-------
MERCURY (mg/kg)
0 04 OS 1.2 16 20 2.4
0-
0.2
0.4
•a
>>
0.6
o.
Ul
o
0.8-
1.0-
1.2 J
01234
RATIO TO CLEANUP GOAL
CI-91
MEAN LOWER LOW WATER
FEASIBLFTY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEGMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
SEGMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
CI-91
Figure 10-5. Areal and depth distributions of mercury in sediments at the
head of City Waterway, normalized to long-term cleanup
goal.
10-8
-------
• Martinac Shipbuilding is considering a dredging project in
City Waterway within the next year (Gerrard, K.( 9 November
1988, personal communication). The project would involve
dredging approximately 4-5 ft deep in an area approximately
50 ft x 300 ft (2,780 yd3).
• City Marina, Inc. added some riprap in front of its building
along the waterway in summer 1987, but no material was
dredged (Anonymous, 28 October 1987, personal communication).
• Industrial Rubber Supply, Western Steel Fabricators, Harmon
Furniture, J.D. English Steel Company, Puget Sound Plywood,
and Totem Marina do not plan any dredging projects
(Elmore, D., 22 October 1987, personal communication;
Anonymous, 27 October 1987b, personal communication;
Whitman, M., 27 October 1987, personal communication;
Saylor, B., 27 October 1987, personal communication;
Chamblin, D., 22 October 1987, personal communication;
Anonymous, 27 October 1987a, personal communication).
10.2 POTENTIAL SOURCES OF CONTAMINATION
Sources of contamination at the head of City Waterway probably date
back to the late nineteenth century. Industries along the waterfront in the
1890s and early 1900s included 10-15 warehouses and dock storage facilities,
at least 7 lumber mills, 2 foundries, several food processing and storage
companies, and 2 electric companies. Existing industries (see Figure 10-1)
that were present prior to 1920 include Harmon Furniture, Fick Foundry,
Northern Fish Products (now Ocean Fish), and Union Oil of California
(Ruckelshaus 1985).
Much of the western shore of the waterway is currently occupied by
marinas and storage facilities. North Pacific Plywood, located on the
western shore since at least 1960, recently moved to Graham, Washington.
Harmon Furniture, George Scofield Company, two seafood processors, and a
wholesale produce distributor remain on the west side. Major reconstruction
on the west side of the waterway is occurring with the building of a new
15th Street bridge across the waterway (Tetra Tech 1985a).
American Plating is located near the head of the waterway along its
eastern shore. The firm has been present at this location (with other names
and owners) since about 1955. Marinas front the eastern shoreline of the
waterway as far north as 15th Street. Burlington Northern and Union Pacific
Railroad yards and several large grocery warehousing facilities are on the
east side of D Street near the head of the waterway. Martinac Shipbuilding,
north of 15th Street, has been at this location since 1925 Tetra Tech
1985a).
Table 10-1 provides a summary of problem chemical and source status
information for the area. Storm drains and the Martinac Shipbuilding
operation are the largest potential sources of metals contamination in the
head of City Waterway. Storm drains have also been shown to contribute
10-9
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TABLE 10-1. HEAD OF CITY WATERWAY - SOURCE STATUS3
Chemical/Group
Total organic carbon
Grease and oil
LPAH
HPAH
Phenol
Zinc
Copper
Lead
t— '
O
i Mercury
Q Cadmium
Nickel
1 ,4-Oichlorobenzene
2 Methyl phenol
4 Methyl phenol
Bis(2-ethylhexyl)phthalate
Butyl benzyl phthalate
N-nitrosodiphenylamine
Aniline
Benzyl alcohol
Chemical
Priority1*
1
2
2
2
2
1
2
1
1
2
2
3
2
2
2
2
3
3 (CI-01)
3 (CI-11)
Sources
Storm drains, mainly
CN-237 and CS-237
Chevron
Storm drains
Ubiquitous oil spills
Harina fires ,
TMOBI Spur eo*l
gasification
Storm drains
Hartinac Shipbuilding
American Plating
Tacoma Spur coal
gasification
Storm drains
American Plating
Unknown
Storm drains
Union Pacific Rail-
road (glue wastes)
N. Pacific Plywood
Tacoma Spur
Storm drains
Storm drain
Ship bilges
Unknown
Storm drains, head
of City Waterway
Storm drains, head
of City Waterway
Source ID
Yes
Potential
Yes
Potential
Potential
Potential
Yes
Potential
Potential
Potential
Yes
Potential
Potential
Potential
Potential
Potential
Potential
Potential
Potential
No
Potential
Potential
Source Loading
Yes
No
Yes
No
No
No
Yes
No
No
No
Yes
No
Insufficient data
No
No
No
No
Insufficient data
No
No
No
No
Source Status
Ongoing
Ongoing
Ongoing
Ongoing, sporadic
Historical
Ongoing
Ongoing
Ongoing
Closed 1985
Ongoing
Ongoing
Closed 1985
Unknown
Ongoing
Closed 1985
Ongoing
Ongoing
Ongoing
Ongoing, sporadic
Ongoing
Ongoing
Ongoing
Sediment Profile Trends
Fairly constant over surface
200 cm
HPAH fairly constant over
surface 200 cm. LPAH has near-
surface maximum
Fairly constant over surface
20 cm. Lead has surface
minimum
Mercury and cadmium
have surface minimum
2 -Methyl phenol has surface
maximum. 4-Methyl phenol has
surface minimum
c
c
c
c
a Source information and sediment information blocks apply to all chemicals in the
respective group, not to individual chemicals only.
b For Priority 3 chemicals, the station exceeding AET is noted in parentheses.
c Not evaluated for this study.
-------
significant quantities of HPAH. In addition, groundwater seepage is a
source of HPAH, and the American Plating site is a potential source of
cadmium and other metals.
10.2.1 Storm Drains
Approximately 45 storm drains discharge into the head of City Waterway
(Figure 10-6). The drainage basin includes most of the downtown Tacoma
business district, the Nalley Valley area, portions of south Tacoma, and
portions of the tideflats between City Waterway and the Puyallup River. Six
of the storm drains have been identified as significant contaminant sources:
CN-237, CS-237, CI-225, CI-230, CI-243, CI-245. Storm drain CI-235 is also
a known source of metals contamination.
Where data are available, storm drain loading calculations for the
nearsnore/tideflats area have been updated to include data collected since
the completion of the Remedial Investigation (Tetra Tech 1985a, 1986c).
However, City of Tacoma data collected as part of the storm drain monitoring
program have not been included. Summary loading tables for the Priority 1
and 2 contaminants of concern for the head of City Waterway (i.e., cadmium,
copper, lead, mercury, nickel, zinc, LPAH, HPAH, phenol, 2-methylphenol,
4-methylphenol, bis(2-ethylhexyl)phthalate, and butyl benzyl phthalate) are
provided in Appendix E, Tables E-20 through E-34.
Storm Drains CN-237 and CS-237--
The Nalley Valley drain (CN-237) is the largest storm drain in the
basin, serving approximately 2,800 ac south and east of the head of City
Waterway (Figures 10-6 and 10-7). Commercial and industrial development is
primarily concentrated around the Interstate-5 and South Tacoma Way corridors
in the center of the drainage basin. The northern and southern portions of
the basin are mainly residential. Nalleys and Atlas Foundry both have NPDES
discharge permits to discharge to this storm drain.
The south Tacoma drain (CS-237) serves approximately 2,200 ac directly
south of the head of City Waterway. The south Tacoma drainage basin is
about 10 blocks wide, extending from the head of the waterway (South 23rd
Street) south to about South 85th Street in south Tacoma. Land use in the
basin is primarily residential. Most of the industrial and commercial
activity is concentrated in the northern portion of the drainage basin near
the Interstate-5 corridor. Together, storm drains CN-237 and CS-237 account
for approximately 85 percent of the flow from the six major storm drain
sources identified above.
The City of Tacoma sewer utility has been conducting inspections at
businesses operating in the Nalley Valley and south Tacoma drainage basins
to identify potential industrial or sanitary connections to the storm drain
systems. Few problems have been found because most industries in the area
discharge process wastewater to the sanitary sewer system, and because the
storm and sanitary sewer systems were separated in the late 1960s. The
most common storm drain problem found during the inspections involves the
discharge of wash water from vehicle and engine wash operations (i.e.,
10-11
-------
o
I—•
ro
T??o
II SURFACE DRAW
10^— OUTFALL AND DRAW Nl»»EH
•- FLOW DIRECTION
SEE FIGURE 1O-7 FOR DRAMAOE Bf.SH
Ral«r«fioe. Irom TBOo*na-PI0rc« Courfy H«allh Depwlment (1983)
Figure 10-6. Surface water drainage pathways to the head of
City Waterway.
-------
COMMENCEMENT
TACOMA J^
5;ife^: U
BUSINESSES WITH DRAINAGE PROBLEMS
(IDENTIFIED DURING SEWER UTILITY INSPECTIONS)
Figure 10-7. Drainage basins (or City Waterway
10-13
-------
automobile dealers, car washes, and automobile detailers) to the city storm
drains. A few sanitary connections were found in an unsewered section along
South Tacoma Way. Discharges of industrial process water to storm drain
catch basins were identified at two businesses (Robinson, R., 25 August
1987, personal communication). Specific problems identified during the
business inspections are summarized in Table 10-2.
Tetra Tech (1985a) identified the Nalley Valley and south Tacoma storm
drains as historical sources of contamination in City Waterway. Both drains
functioned as sewer outfalls until the late 1960s, when the city rerouted
sanitary and industrial wastes from City Waterway to the central wastewater
treatment plant. Although not all cross-connections were corrected at the
time, the Tacoma sewer utility believes that most were eliminated by 1979,
when a new interceptor was installed.
As part of its storm drain monitoring program, the City of Tacoma has
been monitoring effluent from CN-237 and CS-237 since October 1986. Data
from four sampling periods are available (Getchell, C., 12 October 1987,
18 December 1987, 8 February 1988, 19 August 1988, personal communications).
Analyses of particulate matter in effluent from these storm drains have
shown lead concentrations to exceed long-term goals (450 mg/kg) in approxi-
mately half of the samples. Cadmium did not exceed long-term goals
(5.1 mg/kg) in any samples from CS-237, but did exceed long-term goals in
four of seven samples from CN-237. Although not an indicator chemical,
nickel was measured at concentrations over the long-term goal of 140 mg/kg
in six of seven samples of particulate matter from both CN-237 and CS-237.
HPAH concentrations in particulate matter were over the long-term goal of
17,000 ug/kg in one of seven samples collected from drain CS-237 and four of
seven samples from CN-237. The comparison of storm drain particulate matter
with long-term goals assumes no mixing of sediments with cleaner material
from other sources. Such comparisons provide a worst-case analysis of the
impact of storm drain discharge on the waterway.
Individual loading calculations in Appendix E for the problem chemicals
vary over 2 orders of magnitude among sampling events. Recent data obtained
from two dry-weather sampling events by the City of Tacoma confirm this
variability (Getchell, C., 18 December 1987 and 8 February 1988, personal
communications). Loading estimates for CS-237, based on these data for
whole water samples, are 3.5 and 0.89 Ib/day for lead, and 1.3 Ib/day and
not measurable for cadmium. Loading estimates for CN-237, based on the same
data set, are 8.7 Ib/day and not measurable for lead, and 0.2 Ib/day and not
measurable for cadmium (Odell, C., 20 April 1988, personal communication).
In general, loadings for indicator chemicals presented in Appendix E are
similar to those expected due to typical urban runoff reported by Metro
(Stuart et al. 1988). However, in samples collected by the City of Tacoma
since Appendix E was prepared, cadmium concentrations were greater than those
expected in typical urban runoff in three out of seven samples for CS-237 and
five out of seven samples for CN-237.
10-14
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TABLE 10-2. COMMERCIAL DISCHARGES TO STORM DRAINS CN-237 AND CS-237
IDENTIFIED DURING SEWER UTILITY BUSINESS INSPECTIONS
Industry Name
Type of Discharge to Storm Drain
Action Taken
CN-237:
Top Auto
Cammarano Brothers
Western Furnace
Rollins Truck Leas-
ing
Star Rental, Inc.
Smitty's Fleet
Service
City of Tacoma,
Shops 2 and 3
Alpac Corp.
Big Toys
Tacoma News Tribune
TAM Engineering
38th Street Shell
Station
Inadequate sumps to control oil
and grease in discharge from
floor drains
Truck washing area
Vehicle wash area
Vehicle wash area
Equipment wash area
Vehicle wash area
Caustic rinse water from
parts cleaning operations
Floor drains from engine
repair area
Vehicle wash area
Overflow from wood-staining
operations
Vehicle maintenance and washing
area
Old oil/water separator inade-
quate to control discharge from
yard area
Floor drains
Lease terminated.
Letter sent to company.
Oil/water separator installed and
connected to sanitary sewer.
Plans for oil/water separator and
connection to sanitary sewer
approved. Installation by 10/1/87.
Oil/water separator installed and
connected to sanitary sewer.
Installed wash pad, oil/water sepa-
rator, connected to sanitary sewer.
Facilities will not be used until
controls installed.
Plans and specifications for oil/
water separator approved. Construc-
tion scheduled for 9/87.
Closed recycle system installed.
Discharge to city storm drain elimi-
nated.
Connected to sanitary sewer.
TAM has hired consultant to design
new control system.
Station closed. Property to be
sold. Owner notified of illegal
drain.
10-15
-------
TABLE 10-2. (Continued)
Industry Name
Type of Discharge to Storm Drain
Action Taken
Star Ice & Fuel
Personal Touch Car
Detailing
Improper handling of oily prod- Oily wastes near drain have been
ucts--oil has been entering .cleaned up (5/11/87).
storm drain
Vehicle wash area
Nalley's Fine Foods Brine water overflow
Solar Manufacturing Lavatory
Peake, Inc.
CS-237:
Tacoma Plastics
Old-Fashioned Car
Prep
Eagle Paper Box Co.
Floor drain
Oil in floor drain
Engine wash/degrease area
Storm drain catch basin near
chemical storage area
Wash water temporarily discharged
onto ground away from storm drain.
Overflows will be routed to sanitary
sewer, operational controls until
piping installed. DOE writing
NPDES permit for cooling water
discharge; city writing pretreatment
permit.
Building is empty and posted "No
Occupancy" until illegal connection
removed.
Letter sent to company requiring
correction.
Oily wastes near storm drain cleaned
up (5/11/87),
Owner is degreasing engines at
another acceptable location until
connection to sanitary sewer is
completed.
Company's spill plan under review
by sewer utility.
References: Robinson, R., 10 August 1987 and 31 August 1987, personal communications.
10-16
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Storm Drains CI-225 and CI-230--
Storm drains CI-225 and CI-230 serve portions of the downtown Tacoma
business and residential areas. CI-225 drains the 10-ac commercial area
bounded by Dock Street, Pacific Street, 7th Street, and 12th Street (see
Figures 10-6 and 10-7). Annual runoff from the basin is estimated at
20 ac-ft/yr (0.03 ft3/sec) based on average rainfall of 37 in/yr and a
runoff coefficient . of 0.7. Discharge consists entirely of stormwater
runoff. The Tacoma-Pierce County Health Department has reported flows of
3-15 gal/min (0.007-0.03 ft3/sec) in CI-225 (Hanowell, R-, 16 June 1987,
personal communication). CI-225 currently receives runoff from part of the
Tacoma Spur highway project. Ecology has received several reports of a
white, milky-colored discharge from CI-225 that was caused by discharges of
latex from the construction area (Morrison, S., 9 June 1987, personal
communication). Discharges of latex, used as a whitener in the concrete mix
for the road surface, from the construction project have occurred periodical-
ly during construction.
CI-230 serves about 530 ac consisting of a large part of the downtown
Tacoma business district and a portion of the residential section of Tacoma
west of the business district (see Figure 10-7). Annual discharge from
CI-230 is estimated at 900 ac-ft/yr (1.2 ft3/sec), using a runoff coefficient
of 0.6.
During its inspections, the Tacoma sewer utility discovered only five
businesses that discharged wastewater to CI-230. All discharges consisted
of wash water from vehicle and engine washing operations (Table 10-3) and
have ^since been rerouted to the sanitary sewer system. The downtown
business district contributes cooling water discharges from office and
computer air conditioning equipment, possibly containing algicides and
corrosion control chemicals. It is not known how many facilities discharge
to the city storm drains. However, the Tacoma sewer utility believes that
most facilities discharge to the sanitary sewer system (Robinson, R.,
25 August 1987, personal communication).
Dames & Moore (1982) report that Burlington Northern operated a
railroad car washing facility in the CI-230 drainage basin. In the past,
residues that were washed out of the cars, including grains, solvents,
chemicals, and oils, were dumped onsite and were probably transported to City
Waterway in stormwater runoff.
The City of Tacoma has been monitoring effluent from CI-230 since
October 1986. Analyses of particulate matter from CI-230 have shown lead
and mercury concentrations to be consistently over the long-term goals.
Cadmium exceeded long-term goals in over 50 percent of the samples.
Although not indicator chemicals, zinc, copper and nickel were also
consistently measured over the cleanup goals of 410, 390 and >140 mg/kg,
respectively. HPAH and LPAH concentrations in particulate matter were over
the long-term cleanup goals in all seven samples collected (Getchell, C.,
12 October 1987, 18 December 1987, 8 February 1988, 19 August 1988, personal
communications).
10-17
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TABLE 10-3. COMMERCIAL DISCHARGES TO STORM DRAIN CI-230 IDENTIFIED DURING
SEWER UTILITY BUSINESS INSPECTIONS
Industry Name
Type of Discharge to Storm Drain
Action Taken
Downtown Auto Detail
L.H. Bates Vocational
School
Pierce County Fleet
Service
Budget Rent-A-Car
Rely On Automotive
Auto- and engine-washing waste-
water
Rinse tank for small engines
Vehicle washing area
Vehicle washing area
Vehicle washing/repair area
Improvements to drainage sump and
effluent has been rerouted to sani-
tary sewer system.
Training operation has moved to a
new facility with state-of-the-art
equipment.
Discharge rerouted to sanitary
system
Discharge rerouted to sanitary
system.
Business is relocating.
Reference: Robinson, R., 10 August and 31 August 1987, personal communications.
10-18
-------
Individual loading calculations (see Appendix E) for the problem
chemicals vary greatly among sampling events. Recent data obtained from two
dry-weather sampling events by the City of Tacoma for CI-230 confirm this
variability (Getchell, C., 18 December 1987 and 8 February 1988, personal
communications). Loading estimates for CI-230 based on these data are
1.5 and 65 Ib/day for zinc, 0.8 and 4.7 Ib/day for lead, and not measurable
for mercury (Odell, C., 20 April 1988, personal communication). The lead
loading of 4.7 Ib/day is much higher than estimates reported in Appendix E
based on four previously collected samples. The 65 Ib/day zinc loading is
also higher than previous estimates reported in Appendix E. The City of
Tacoma loading estimates should be qualified since city staff experienced
difficulty in obtaining flow measurements (Odell, C., 20 April 1988,
personal communication).
Loading estimates for CI-225 and CI-230 presented in Appendix E are
not, in general, elevated over average urban runoff (residential, commercial,
and highway) reported by Metro (Stuart et al. 1988) for the indicator metals
(cadmium, lead, and mercury).
Storm Drains CI-243 and CI-245--
Storm drains CI-243 and CI-245 serve drainage basins located in the
southeast corner of City Waterway (Figure 10-6). CI-243 drains approximately
90 ac of the Union Pacific and Burlington Northern Railroad yards. Annual
runoff from the basin is estimated at 110 ac-ft/yr (0.2 ft^/sec) based on
average rainfall of 37 in/yr and a runoff coefficient of 0.4. CI-245 drains
an area of approximately 50 ac, which includes the railroad yards, the
Emerald Products property, and part of the Pacific Cold Storage property.
Runoff from the CI-245 basin is estimated at 110 ac-ft/yr (0.2 ft3/sec)
based on a runoff coefficient of 0.7.
Ecology collected sediment samples from both CI-243 and CI-245 in
June 1987. Data from this study were reported by Norton (15 April 1988,
personal communication). Of the indicator metals measured in sediments from
CI-243, only mercury concentrations exceeded the long-term cleanup goal.
Sediment from this storm drain also had a concentration of HPAH over the
long-term cleanup goal. In sediment samples from CI-245, concentrations of
all three metal indicator chemicals exceeded the long-term cleanup goals.
No HPAH contaminants were measured in the sediment from this storm drain.
As indicated in Appendix E, very few loading estimates are available
from drains CI-243 and CI-245 for the indicator chemicals cadmium and lead.
No mercury data are available from either storm drain. No loading estimates
are available for HPAH from CI-243 and only one estimate is available from
CI-245.
Storm Drain CI-235--
Ecology also collected sediment samples CI-235. This drain was
included because the drainage basin includes the area around the new Tacoma
Spur freeway system (SR-705), which is the former location of a coal
gasification facility. Waste products from the coal gasification process
10-19
-------
were removed as part of the freeway construction. Discharge to this storm
drain consists entirely of stormwater runoff. Measured concentrations of
all indicator metals and HPAH in storm drain sediment exceeded the long-term
goals (Norton, D., 15 April 1988, personal communication).
10.2.2 Martinac Shipbuilding
Site Background--
Martinac Shipbuilding has operated a shipbuilding facility at 401 East
15th Street on City Waterway since 1924. Martinac is involved primarily in
the design and construction of large commercial vessels, although some ship
repair work is also conducted.
The Martinac facility is considered a potential source of arsenic,
copper, and zinc because the concentrations of these metals in sediments
offshore of the facility were 2-10 times as great as those elsewhere in City
Waterway (Norton and Johnson 1984). The offshore sediment sample that
exhibited the highest metals concentrations was composed of 95 percent sand
and appeared to be sandblasting material.
Identification of Contaminant Reservoirs Onsite--
The operations associated with metals contamination at the Martinac
facility include sandblasting and painting. Sandblasting is primarily used
to clean welds (Martinac, Jr., 11 November 1987, personal communication).
Sandblasting for ship repair and paint removal is a relatively minor part of
the current operations because Martinac is involved primarily with new con-
struction that utilizes preprinted steel requiring no sandblasting. Contami-
nation associated with sandblasting may be more heavily related to past oper-
ations and waste disposal practices. Ecology inspected the Martinac facility
in summer of 1986 and reported that spent sandblast grit had accumulated along
the intertidal areas (Backous B., 22 October 1987, personal communication).
Martinac currently uses Tuf-Kut blasting sand. Waste blasting material
found on the beach at the Martinac facility contained 213 mg/kg arsenic,
2,120 mg/kg copper, 125 mg/kg lead, and 1,690 mg/kg zinc (Getchell, C.,
23 December 1986a, personal communication). However, in the past, many of
the shipyards in the Commencement Bay area used ASARCO slag as sandblast
grit. Typical metals content of ASARCO slag is 9,000 mg/kg arsenic,
5,000 mg/kg copper, 5,000 mg/kg lead, and 18,000 mg/kg zinc (Norton and
Johnson 1984).
The primary routes of contamination from paint and painting activities
include spills, overspray, drift, and removal during sandblasting operations.
Metals are used as additives in many biofpuling paints and constitute
2-60 percent by volume of commercial marine paints (Muehling 1987). Prior to
1975, various mercury compounds were often used as antifoul ants. However,
after 1975, cuprous oxide replaced mercury as the primary antifoul ant
(Muehling 1987). Organotins are generally used in conjunction with copper
to increase the service life of the antifoulant paint and are used exclusive-
ly on aluminum hulled boats because of the corrosivity of cuprous oxide.
10-20
-------
The typical composition is 7-8 1b cuprous oxide and 1.5 Ib organotin per
gallon of paint.
Recent and Planned Remedial Activities--
Ecology is currently involved in a shipyard pollution education
program. The program includes workshops to inform shipyard owners of best
management practices and NPDES permit application procedures. Although
shipyards in the Commencement Bay area are not currently permitted under the
NPDES program, Ecology plans to write permits for all shipyard facilities.
Permit requirements will include best management practices to prevent
sandblast grit and other materials from entering the waterways, as well as
monitoring requirements for oil, grease, turbidity, and metals.
Martinac currently conducts most sandblasting activities onshore away
from the water in a covered area protected from the wind to prevent sand-
blasting grit from entering City Waterway (Martinac Jr., 11 November 1987,
personal communication). Spent sandblast material is collected, temporarily
stored onsite, and periodically removed by a contractor. During their 1986
inspection, Ecology reported that Martinac had instituted suitable contain-
ment procedures for dockside sandblasting, including installation of a boom
and visqueen curtain around the vessel to collect spent sandblast material
(Backous B., 22 October 1987, personal communication).
Most painting operations are completed before the vessel is put in the
water. Painting is conducted in an enclosed paint shop for smaller jobs and
inside construction buildings for larger projects (Martinac Jr., 11 November
1987, personal communication). For large outside painting projects, nearby
catch basins are covered with plastic to prevent spilled material from
entering the waterway via the storm drain system. Dockside painting, when
required, is applied with rollers rather than sprayers to eliminate overspray
problems (Stoltenberg, S., 11 November 1987, personal communication).
10.2.3 Groundwater
Hart-Crowser & Associates (1984) reported that groundwater was
contaminated in the vicinity of the Tacoma Spur highway project (SR-705) at
the former location of a coal gasification plant. This facility was located
between 21st and 24th Streets and A and Dock Streets. Groundwater adjacent
to City Waterway near the head was contaminated with PAH and other one-ring
compounds (e.g., benzene, toluene). Hart-Crowser & Associates (1984)
indicated that other sources, in addition to waste from the coal gasifica-
tion, were potentially contributing to this contamination. Other potential
contributors include an abandoned gasoline station at Puyallup and A Streets,
an equipment storage yard, a coal- and wood-powered electricity generating
plant, and petroleum product and storage tanks.
As part of constructing SR-705, the Washington Department of Transpor-
tation removed 4,500 tons of PAH-contaminated soil to a hazardous waste
disposal facility in Arlington, Oregon. In addition, approximately 13,000
tons of soil contaminated with PAH to a lesser degree were placed in three
concrete vaults near Interstate-5. A groundwater monitoring program is being
10-21
-------
implemented in the area where waste was removed to assess impacts of the
removal action on groundwater contamination levels.
10.2.4 American Plating
Site Background--
Between 1955 and January 1986 metal electroplating operations were
conducted at 2110 East D Street near the head of City Waterway. Activities
took place under the names Puget Sound Plating, Seymour Electroplating, and
in 1975, American Plating. Metals used in American Plating's operations
included cadmium, copper, nickel, and zinc, which are identified as contami-
nants of concern in City Waterway (Tetra Tech 1985a, 1986c). Chromium was
also used.
Prior to 1978, American Plating had an NPDES permit to discharge
process wastewaters directly into City Waterway. Information in Ecology
files indicates that there were numerous permit violations (Tetra Tech
1985a). Permitted discharges were discontinued when, subsequent to 1978,
American Plating was connected to the Tacoma sewer utility sanitary sewer
lines. According to Ecology files, plating wastes have been spilled on the
site at least 10 times since 1979. For example, on 6 October 1981 an unknown
volume of waste containing 4 mg/L zinc was spilled on the property. On
6 December 1984 the company reported a spill of zinc-contaminated material
into the waterway. The volume of this waste spill was not estimated.
Chemicals and other hazardous materials associated with the plating
processes remained even though operations ceased in 1975. Under the
direction of Ecology these hazardous materials have been removed. However,
contaminated soils and groundwater may continue to contribute metals to the
waterway.
Identification of Contaminant Reservoirs Onsite--
The primary known metals reservoir onsite is contaminated surface soil.
(Groundwater quality has not been evaluated.) Contaminants in the soil may
be transported to the waterway via overland runoff or, if infiltrating
runoff leaches metals from the soil into groundwater, via groundwater.
Recent and Planned Remedial Activities--
The cleanup of process-related hazardous materials on the site and
preliminary soil tests were conducted under the framework of a Consent Order
from Ecology. A soil and groundwater investigation is being conducted at
the site to define the magnitude and extent of contamination.
10.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
10-22
-------
available for source control, and source control measures that have been
implemented to date. Second, the potential success of source control was
evaluated. This evaluation was based on levels of contamination in sediments
and assumptions regarding the relationship between sources and sediment
contamination. Included within the evaluation was an estimate of the degree
of source control needed to maintain acceptable levels of sediment contami-
nants over the long term.
10.3.1 Feasibility of Source Control
Four major kinds of sources of contamination have been identified for
the head of City Waterway: storm drains (metals, HPAH), the Martinac
shipbuilding facility (metals), groundwater seepage (HPAH), and American
Plating (metals). Of the roughly 45 storm drains that discharge to head of
City Waterway, drains CS-237, CN-237, CI-230, CI-225, CI-243, and CI-245
appear to be the major sources of problem chemicals to the waterway. The RI
also identified historical sources of HPAH (Tetra Tech 1985a). Source
controls have been implemented or may be required for the following
mechanisms of contaminant discharge:
• Improper drain connections (storm drains)
• Occasional direct spills (ship discharges)
• Groundwater transport of contaminants (movement through
buried wastes)
• Surface runoff (including storm drains from Martinac
Shipbuilding, American Plating).
The level of source control assumed to be feasible for each of the potential
major sources is presented in Table 10-4.
Storm Drains--
Several storm drains discharging to head of City Waterway have been
identified as ongoing sources of metal contaminants and PAH to the waterway.
Storm drains CS-237, CN-237, CI-230, CI-225, CI-243, and CI-245 appear to
be the major conduits through which problem chemicals enter the waterway.
Available technologies for controlling surface water runoff to storm
drains are summarized in Section 3.2.2. The technologies include methods
for retaining runoff onsite (e.g., berms, channels, grading, sumps),
revegetation or capping to reduce erosion of waste materials, and waste
removal or treatment.
Treatment methods for stormwater after collection in a drainage system
also exist. Sedimentation basins and vegetation channels (or grassy swales)
have been shown to remove contamination associated with particulate matter.
Removals of up to 75 percent for total suspended solids and 99 percent for
lead have been reported for detention basins (Finnemore and Lynard 1982;
Homer and Wonacott 1985). Removals of 90 percent for lead, copper, and
10-23
-------
TABLE 10-4. EFFECTIVENESS OF SOURCE CONTROL FOR HEAD OF CITY WATERWAY
Source
Storm Drains
CN-237, CS-237
CI-225, CI-230,
CI-243, CI-245
Other Storm
Drains
t-*
0
ro Martinac
*• Shipbuilding
Frequency of Detection
in Effluent* (%)
HPAH Cd Pb Hg
86
40 44
45
- N/Ab
75
70
100
N/Ab
14
43
(CI-248)
50
N/Ab
Estimated Average
Annual Discharge
(Mgal/yr)
2,250
1.140
150
Unknown
Feasible Source
Average Load Control Assumed
(Ib/day) (%)
Pb=2.2 50
Hg=0.0015
Cd=0.004
Pb=0.38 50
Hg=0.008
Cd=0.0016
HPAH=<0.002
Pb=0.008
Hg=9.2xlO"b 50
Cd=0.0017
(In offshore sedi- 95
ments)
ni i A * *»no /I
Rationale for Percent Source Control
Business inspections conducted in basins by City of Tacoma
did not identify any major discharges.
Assumed nonpoint source pollution reduced by 50 percent as
result of implementation of best management practices
(BMPs) and public education program instituted by Tacoma-
Pierce County Health Department (TPCHD).
Same as above.
Assumed nonpoint source pollution reduced by 50 percent as
result of implementation of BMPs and public education
program instituted by TPCHD.
Contamination appears to be caused by historical sandblasting
operations and waste handling practices. .
Pb=244-382 mg/kg
Hg=0.035-0.4 mg/kg
Cd=1.02-2.04 mg/kg
Groundwater
American Plating
,N/A°
~ N/Ab N/Ab N/Ab
Unknown Unknown
Unknown (In offshore sedi-
ments)
Pb=737-817 mg/kg
Hg=0.23-0.35 mg/kg
Cd=1.53-5.61 mg/kg
50
90
Current activities primarily involve new construction, with
minimal sandblasting.
Ongoing sandblasting and painting operations have been
modified. Facility will be permitted under NPDES program.
Groundwater seepage is probably a source of HPAH. Soil
cleanup has been performed to reduce groundwater
contamination.
No longer in operation, facility demolished, tank plating
solutions removed.
Site cleanup expected under Ecology Consent Order.
a Indicator chemicals for head of City of Waterway are high molecular weight polynuclear aromatic hydrocarbons (HPAH), cadmium (Cd), lead (Pb), and mercury (Hg).
provided in Appendix E; does not include data from City of Tacoma monitoring program.
Data
N/A = Probable source, frequency data not available.
-------
zinc and 80 percent for total suspended solids have been achieved using
grassy swales (Homer and Wonacott 1985; Miller 1987).
Contaminant reductions of 50 percent in the storm drains surrounding
head of City Waterway are assumed to be achievable through implementation of
all known, available, and reasonable technologies.
Martinac Shipbuilding--
Martinac Shipbuilding has been associated with elevated concentrations
of metal contaminants in adjacent sediments. Sandblasting grit and anti-
fouling paints are the suspected sources of metals to the Waterway from
operations at Martinac. However, much of the contamination in the vicinity
of Martinac Shipbuilding appears to be associated with historical sand-
blasting activities. More recently, sandblasting has been curtailed and
practices have been revised to limit contamination of the waterway. It is
assumed that implementation of these practices will reduce contaminant
loading from this source by 95 percent.
Groundwater--
Groundwater contamination in the area near the head of City Waterway on
the west side has been shown to be contaminated with PAH among other
organic compounds. Available technologies for controlling the migration of
contaminants via groundwater are summarized in Section 3.2.1. General
categories of technologies include removal of contaminant source, containment
(e.g., slurry walls), collection, in situ treatment, and post-removal
treatment. Approximately 17,500 tons of contaminated soil has already been
removed by the Washington Department of Transportation. It is assumed that
through implementation of measures such as this, contaminant reductions in
groundwater seepage can be reduced by 50 percent.
American Plating--
American Plating has been identified as a potential source of metals to
City Waterway (Tetra Tech 1985a). Ongoing contamination of the waterway
from American Plating may occur via surface water runoff, groundwater flow,
or both. Available technologies for controlling surface water runoff are
summarized in Section 3.2.2. Technologies for control of contamination in
surface water include methods for retaining runoff onsite (e.g., berms,
channels, grading, sumps), revegetation or capping to reduce erosion of
waste materials, and waste removal or treatment. General categories of
technologies for contaminant control in groundwater include removal of
contaminant source, (e.g., slurry walls), collection, in situ treatment, and
post-removal treatment. Cleanup of process-related hazardous materials on
the site under a Consent Order from Ecology is expected to result in a
90 percent reduction in contamination from this source.
Conclusions—
Implementation of these measures should result in a significant
reduction in contaminant discharges. Given the contaminant types, multi-
10-25
-------
plicity of sources, lack of defined sources in some cases (e.g., storm
drains and groundwater contamination near the head of the waterway), and
available control technologies, it is estimated that implementation of all
known, available, and reasonable control technologies will reduce contaminant
loadings by 60 percent for both the indicator metals (cadmium, lead, and
mercury) and HPAH.
10.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals. Results are reported in full in Tetra
Tech (1987a). A summary of those results is presented in this section.
The depositional environment in the head of City Waterway varies
throughout the problem area. A sedimentation rate of 600 mg/cm2/yr
(0.43 cm/yr) and a mixing depth of 10 cm were selected to represent the
depositional environment. Four indicator chemicals (HPAH, cadmium, lead, and
mercury) were used to evaluate the effect of source control and the degree
of source control required for sediment recovery. Two timeframes were
considered: a reasonable timeframe (defined as 10 yr) and the long term.
Losses due to biodegradation and diffusion were determined to be negligible
for these chemicals. Source loadings for all indicator chemicals were
assumed to be in steady-state with sediment accumulation. Results of the
sediment recovery evaluation are summarized in Table 10-5.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times are predicted to
be 2 yr for HPAH, 13 yr for cadmium, 14 yr for lead, and 24 yr for mercury.
Only for HPAH is sediment recovery predicted to be possible in a reasonable
timeframe (i.e., 10 yr). These predictions are based on the highest
concentrations of indicator chemicals measured in the problem area. Because
the source loadings of all indicator chemicals at the head of City Waterway
are assumed to be in steady-state with sediment accumulation, reductions in
sediment concentrations are not predicted unless sources are controlled.
Effect of Implementing Feasible Source Controls--
Implementation of all known, available, and reasonable source control
is expected to reduce source inputs by 60 percent for all indicator
chemicals. With this level of source control, as an input value, the model
predicts that sediments with an enrichment ratio (ratio of the observed
concentration to the cleanup goal) of 1.3 (i.e., concentrations of
21,400 ug/kg for HPAH, 6.6 mg/kg for cadmium, 585 mg/kg for lead, and
0.74 mg/kg for mercury) will recover within 10 yr. The surface area of
sediments not recovering to cleanup goals within 10 yr is shown in
Figure 10-8. For comparison, sediments currently exceeding long-term goals
for the indicator chemicals are also shown.
10-26
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TABLE 10-5. HEAD OF CITY WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Station with Hiahest Concentration
Station identification
Concentration3
Enrichment ratio''
Recovery time if sources are
eliminated (yr)
Percent source control required
to achieve 10-yr recovery
Percent source control required
to achieve long-term recovery
Averaae of Three Hiahest Stations
Concentration3
Enrichment ratio''
HPAH
CI-01
18,660
1.1
2
25
9
17,800
1.0
Indicator
Cadmium
Cll
8.2
1.6
13
NPC
38
7.6
1.5
Chemicals
Lead
CI-91
820
1.8
14
NPc
45
800
1.8
Mercury
CI-13
1.5
2.5
24
NPC
61
0.91
1.5
Percent source control required
to achieve long-term recovery 4 33 44 35
10-Yr Recovery
Percent source control assumed
feasible 60 60 60 60
Highest concentration recovering
in 10 yra 21,400 6.6 585 0.74
Highest enrichment ratio of sediment
recovering in 10 yr 1.3 1.3 1.3 1.3
a Concentrations in ug/kg dry weight for organics, mg/kg dry weight for
metals.
b Enrichment ratio is the ratio of observed concentration to cleanup goal.
c NP = Not possible.
10-27
-------
AT PRESENT
oo
IN10YR
CITY
Head of City Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA(yd2)
VOLUME (yd3 )
IN 10 YR
DEPTH (yd)
AREA (yd 2)
VOLUME (yd3 )
25
230,000
575.000
2.5
171,000
426,000
CZ3
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
HPAH (AET = 17,000 |ig/kg)
MERCURY (AET = 0.59 mg/kg)
CADMIUM (AET = 5.1 mg/kg)
LEAD (AET = 450 mg/kg)
Figure 10-8. Sediments at the head of City Waterway not meeting cleanup goals for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
Source Control Required to Maintain Acceptable Contamination Levels--
As presented in Table 10-5, the percent source control needed to
maintain acceptable contaminant concentrations in freshly deposited sediment
is 4 for HPAH, 33 for cadmium, 44 for lead, and 35 for mercury. These
estimates are based on an average of the three highest sediment concentra-
tions for each indicator chemical measured in the head of City Waterway
problem area. These values are presented for comparative purposes; the
actual percent reduction required in source loading is subject to the
uncertainty inherent in the assumptions of the predictive model. These
values probably represent upper limit estimates of source control require-
ments since the assumptions incorporated into the model are considered to be
environmentally protective.
Percent reductions needed to achieve cleanup goal concentrations of
indicator chemicals in storm drain particulate matter are presented in
Table 10-6. Average values reported for drains CS-237, CN-237, and CI-230
are based on seven samples each collected by the City of Tacoma
(Getchell, C., 12 October 1987, 18 December 1987, 8 February 1988, 19 August
1988, personal communications). The percent reductions needed to achieve
long-term goal concentrations of indicator chemicals in sediments in storm
drains CI-235, CI-243, and CI-245 are based on sediment data reported by
Ecology (Norton, D., 15 April 1988, personal communication).
10.3.3 Source Control Summary
The four most important sources of problem chemicals to the head of
City Waterway are as follows:
• Storm drains (HPAH, metals)
• Martinac Shipbuilding (metals)
• Groundwater seeps (HPAH)
• American Plating (metals).
If these sources are completely eliminated (100 percent source control), it
is predicted that sediment contaminant concentrations in the surface mixed
layer will decline to the HPAH long-term goal of 17,000 ug/kg in 2 yr, the
cadmium long-term goal of 5.1 mg/kg in 13 yr, the lead long-term goal of
450 mg/kg in 14 yr, and the mercury long-term cleanup goal of 0.59 mg/kg in
24 yr. Consequently, sediment remedial action will be required to mitigate
the observed and potential adverse biological effects ,within a reasonable
timeframe.
Prior to initiating sediment remedial actions, additional source
control measures will be needed to ensure that acceptable sediment quality
is maintained. Estimates of the percent reductions required to maintain
acceptable concentrations in freshly deposited sediment are 4 for HPAH,
33 for cadmium, 44 for lead, and 35 for mercury (see Table 10-5).
10-29
-------
TABLE 10-6. AVERAGE PERCENT REDUCTIONS NEEDED TO ACHIEVE
LONG-TERM CLEANUP GOAL CONCENTRATIONS OF INDICATOR CHEMICALS
IN STORM DRAIN EFFLUENT PARTICULATE MATTER OR SEDIMENTS
CS-2373
CN-2373
CI-2303
CI-2355
CI-243b
CI-245b
HPAH
(%)
32
83
90
51
32
0
Indicator
Cadmi urn
(%)
0
44
31
0
0
58
Chemical
Lead
(%)
0
5
58
0
0
43
Mercury
(%)
0
56
50
65
51
73
a Effluent particulate matter; average of seven samples reported by City of
Tacoma (Getchell, C., 12 October 1987, 18 December 1987, 8 February 1988,
19 August 1988, personal communications).
b Sediments; data from Ecology (Norton, D., 15 April 1988, personal
communication).
10-30
-------
Implementation of all known, available, and reasonable control
technologies is expected to provide an approximately 60 percent reduction
of contaminant loadings to the waterway. Therefore, it appears that by
implementing feasible levels of source control, long-term goals for all of
the indicator chemicals can be maintained.
10.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with HPAH, cadmium, lead, or
mercury concentrations currently exceeding long-term cleanup goals is ap-
proximately 575,000 yd3 (see Figure 10-8). This volume was estimated by
multiplying the areal extent of sediment exceeding the long-term cleanup
goal (230,000 yd2) by the estimated 2.5-yd depth of contamination (see
contaminant sediment profiles in Figures 10-2 through 10-5). The estimated
thickness of contamination is only an approximation since only one sediment
profile was collected in this problem area.
The total estimated volume of sediments with HPAH, cadmium, lead, or
mercury concentrations that is expected to exceed long-term cleanup goals
10 yr following implementation of feasible levels of source control is
426,000 yd3. This volume was estimated by multiplying the areal extent of
sediment contamination with enrichment ratios greater than 1.3 (see
Table 10-5), an area of 171,000 yd2, by the estimated 2.5-yd depth of
contamination. These volumes are also approximations, accounting for
uncertainties in sediment profile resolution and dredging tolerances.
The quantity of sediment used in evaluating the remedial alternatives
(i.e., to identify the preferred alternative) was 426,000 yd3. This is also
the volume of sediment requiring remediation for the head of City Waterway.
10.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
10.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion, this set of alternatives is
evaluated to determine the suitability of each alternative for the remedia-
tion of contaminated sediments in the head of City Waterway. Remedial
measures address 426,000 yd3 of contaminated sediments. The objective of
this evaluation is to identify the alternative considered preferable to all
others based on CERCLA/SARA criteria of effectiveness, implementability, and
cost.
The first step in this process is to assess of the applicability of
each alternative in the waterway. Site-specific characteristics that must be
considered in such an assessment include the nature and extent of contamina-
tion; the environmental setting; the location of potential disposal sites;
and the site's physical properties such as waterway usage, bathymetry, and
water flow conditions. Alternatives determined to be appropriate for the
waterway can then be evaluated based on the criteria presented in Chapter 4.
10-31
-------
The indicator chemicals HPAH, cadmium, lead, and mercury were selected
to represent the primary potential sources of contamination to the waterway:
storm drains, Martinac Shipbuilding, groundwater infiltration, and American
Plating (see Table 10-1). Area! distributions for all four indicators are
presented in Figure 10-8 to indicate the degree to which contaminant groups
overlap based on long-term cleanup goals and estimated 10-yr sediment
recovery.
It is assumed that the requirement to maintain navigational access to
the Puyallup River and Sitcum Waterway could preclude the use of a hydraulic
pipeline for nearshore disposal at the Blair Waterway disposal site.
Therefore, clamshell dredging has been chosen for evaluation in conjunction
with the nearshore disposal alternative.
Four of the ten candidate alternatives have been eliminated for the
head of City Waterway. Because total concentrations of metals are generally
greater than 2,000 mg/kg, solvent extraction, thermal treatment> and land
treatment are not applicable. In situ capping is eliminated because of the
need to maintain a navigation channel in City Waterway. The following six
candidate alternatives are evaluated for head of City Waterway:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solidification/upland disposal.
These candidate alternatives are described in detail in Chapter 3. Evalu-
ation of the no-action alternative is required by the NCP to provide a
baseline against which other remedial alternatives can be compared. The
institutional controls alternative, which is intended to protect the public
from exposure to contaminated sediments without implementing sediment
mitigation, provides a second baseline for comparison. The three nontreat-
ment dredging and disposal alternatives remain applicable to remediation of
sediment contamination in the head of City Waterway. Solidification is
retained as an appropriate treatment technology because it is primarily used
to treat materials contaminated with inorganics.
10.5.2 Evaluation of Alternatives
The three primary evaluation criteria are effectiveness, implement-
ability, and cost. A narrative matrix summarizing the assessment of each
alternative based on effectiveness and implementability is presented in
Table 10-7. A comparative evaluation of alternatives based on ratings of
high, moderate, and low in the various subcategories of evaluation criteria
is presented in Table 10-8. For effectiveness, the subcategories are short-
10-32
-------
EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
ERM PROTECTIVENESS
LONG-T
1 CONTAMINANT
| MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION '
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 10-7.
NO ACTION
MA
NA
Original contamination remains.
Source inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative is ranked
sixth overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingeston of contaminated
food species remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxicity and contam-
inant mobilty are expected to
remain at current levels or
Increase as a result of continued
source Inputs. Contaminated
sediment volume increases as
a result of continued source
inputs.
REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE HEAD OF CITY WATERWAY PROBLEM AREA
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during Implementation.
Source control is implemented
and would reduce sediment con-
tamination with time, but adverse
Impacts would persist in the in-
terim. However, an equivalent
volume of clean sediment will be
added to restore the habitat
Access restrictions and mon-
itoring efforts can be imple-
mented quickly. Partial sedi-
ment recovery is achieved nat-
urally, but significant contami-
nant levels persist. Sediment
recovery is improbable within
10 years. This alternative is
ranked fifth overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure is negli-
gible. COM Is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation Is
restricted.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic dredg
ing. Removal with dredge and
disposal with downpipe and dif-
fuser minimizes handling require-
ments. Workers wear protective
gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations. Benthic habitat is
impacted at the disposal site.
Equipment and methods used
require no development period.
Pre-implementation testing Is
not expected to be extensive.
Disposal siting and facility con-
struction may delay project com-
pletion. This alternative is rank-
ed second overall for timeliness.
The long-term reliability of the
cap to prevent contaminant re-
exposure in a quiescent, sub-
aquatic environment is consi-
dered acceptable.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota. Protection Is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment.
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in
situ conditions. •
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM lo a barge offshore during
transport. Public access ID
dredge and disposal sites Is re-
stricted. Public exposure po-
tential is low.
Clamshell dredging of COM in-
creases exposure potential •
moderately over hydraulic
dredging. Workers wear pro-
tective gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Nearshore intertidal habitat
is lost Contaminated sediment
Is resuspended.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment and methods are available.
This alternative is ranked first
for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating COM.
Variable physicochemlcal con-
ditions in the fill increase poten-
tial for contaminant migration
over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment The
potential for contaminant migra-
tion into marine environment
may increase over CAD. Adja-
cent fish mitigation site is sen-
sitive area.
The toxirity of COM in the con-
finement zone remains at pre-
remediation levels. Altered
conditions resulting from
dredge/disposal operations
may increase mobility of metals.
Volume of contaminated sedi-
ments Is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM Is confined to a pipeline
during transport Public access
to dredge and disposal sites Is
restricted. Exposure from COM
spills or mishandling is possible,
but overall potential is low.
Hydraulic dredging confines
COM to a pipeline during trans-
port. Dredge water contamina-
tion may increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment Is
resuspended during dredging
operations. Dredge water can
be managed to prevent release
of soluble contaminants.
Equipment and methods used
require no development period.
Pre-implementation testing Is
not expected to be extensive.
Disposal siting and facility con-
struction delay implementation.
This alternative is ranked third
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating CDM. Al-
though the potential for ground-
water contamination exists, it is
minimal. Upland disposal facili-
ties are more secure than near-
shore facilities.
Upland disposal is secure, with
negligible potential for environ-
mental impact if property de-
signed. Potential for ground-
water contamination exists.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may Increase due to resuspen-
slon of sediment
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Publ c access to dredge treat-
ment and disposal sites is re-
stricted. Exposure from CDM
spills or mishandling Is possible,
but overall potential Is low.
Additional CDM handling asso-
ciated with treatment Increases
worker risk over dredge/disposal
options. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations.
Substantial CDM testing and
equipment development are
required before a solidification
scheme can be implemented.
Extensive bench- and pilot-
scale testing are likely to be
required. This alternative Is
ranked fourth overall for timeli-
ness.
Long-term reliability of solidifica-
tion treatment processes for
CDM are believed to be ade-
quate. However, data from
which to confirm tang-term relia-
bility are limited. Upland dispos-
al facilities are structurally reli-
able
Solidification is a more protec-
tive solution than dredge/dis-
posal alternatives. The poten-
tial for public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Solidification Is a more protec-
tive solution than dredge/dis-
posal alternatives. The poten-
tial lor public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Contaminants are physically
con ained, thereby reducing
toxidty and the potential for
contaminant migration com-
pared with non-treatment alter-
natives. Metals and organics
are encapsulated.
10-33
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| IMPLEMENTABILITY
fc
_i
TECHNICAL FEASIBI
INSTITUTIONAL FEASIBILTY
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH CHEMICAL-
AND LOCATION-
SPECIFIC ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 10-7.
NO ACTION
Implementation of mis alterna-
tive Is feasible and reliable.
No monitoring over and above
programs established under
other authorities are Imple-
mented.
There are no O & M requirements
associated with the no action
alternative.
Approval Is denied as a result of
agency commitments to mitigate
observed biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the intent of CE RCLA/
SARA and NCR because of on-
going impacts.
All materials and procedures are
available.
(CONTINUED)
INSTITUTIONAL
CONTROLS
Source control and Institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily Implemented.
Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
Some O ft M is associated with
monitoring, maintenance of
warning signs, and Issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels in sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
Impacts. State requirements
for source control are achieved.
Coordination with TPCHD tor
health advisories for seafood
consumption is required.
All materials and procedures are
available to implement Institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment is
reliable. Placement of dredge
and capping materials difficult
although feasible. Inherent diffi-
culty In placing dredge and cap-
ping materials at depths of 100 ft
or greater.
Confinement reduces monitoring
requirements In comparison to
Institutional controls. Sediment
monitoring schemes can be
readily Implemented.
O & M requirements are minimal.
Some O & M Is associated with
monitoring for contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM Is treated.
WISHA/OSHA worker protection
is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Waterway CAD site
is considered available. Availa-
bility of open water CAD sites is
uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Moni-
toring Imptementabillty is en-
hanced compared with CAD.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facil-
ity siting are assumed feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been iden-
tified and is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
Is reliable. Secure upland con-
finement technology is well de-
veloped.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring over CAD. Installa-
tion of monitoring systems Is
routine aspect of facility siting.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Coordination is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Solidification technologies for
treating COM on a large scale
are conceptual. Implementation
Is considered feasible, but reli-
ability Is unknown.
Monitoring requirements for so-
lidified material are low In com-
parison with dredge and dispos-
al aTernatives. Monitoring can
be readily Implemented.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment System mainten-
ance Is Intensive during Imple-
mentation.
Disposal requirements are less
stringent for treated dredge ma-
terial, enhancing approval feasi-
bility. However, bench scale
testing Is required to demon-
strate effectiveness of solidifi-
cation.
WISHA/OSHA worker protection
requred. Alternative complies
with U.S. EPA's policies for on-
site disposal and permanent re-
duction in contaminant mobility.
May require that substantive
aspects of CWA and shoreline
management programs be ad-
dressed.
Disposal site availability Is un-
certain but feasible. Solidifica-
tion equipment and methods for
large scale COM disposal are
currently unavailable.
10-34
-------
TABLE 10-8. EVALUATION SUMMARY FOR THE HEAD OF CITY WATERWAY
O
I
No Action
Short-Term
Protecti veness Low
Timeliness Low
Long-Term
Protect! veness Low
Reduction in Toxicity,
Mobility, or Volume Low
Technical Feasibility High
Institutional
Feasibility Low
Availability High
Long-Term Cleanup
Goal Costa
Capital
08.M
Total
Long-Term Cleanup Goal
with 10-yr Recovery
Cost*-6
Capital
O&M
Total
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
2,325
2,331
6
2,101
2.107
Clamshell/
CAO
High
Moderate
High
Low
Moderate
Moderate
Moderate
4,526
604
5,130
3,372
485
3,857
Clamshell/
Nearshore
Disposal
Moderate
Moderate
Moderate
Low
High
Moderate
Moderate
14,086
721
14,807
10,454
572
11,026
Hydraul ic/
Upland
Disposal
Moderate
Moderate
Moderate
Low
High
Moderate
Moderate
25,171
1,121
26,292
18,658
869
19,527
Clamshel I/
Solidify/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
38,121
1,066
39,187
28.260
828
29,088
a All costs are in $1,000.
** Includes sediment for which biological effects were observed for non-indicator compounds.
-------
term protectiveness; timeliness; long-term protectiveness; and reduction in
toxicity, mobility, or volume. For implementability, the subcategories are
technical feasibility, institutional feasibility, and availability. Costs
include capital costs and O&M costs. Remedial costs are shown for sediments
currently exceeding long-term cleanup goal concentrations.
Short-Term Protectiveness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
biological and potential public health impacts continue with the contaminated
sediments remaining in place. Source control measures initiated as part of
the institutional controls would result in reduced sediment contamination
with time but adverse impacts would persist in the interim. It is predicted
that, even with complete source elimination, reduction in sediment concentra-
tions to acceptable levels could require 14 yr for mercury (see Table 10-5).
Except for clamshell dredging/confined aquatic disposal, other alterna-
tives involving dredging are rated moderate for short-term protectiveness.
Removal of contaminated sediments is expected to create short-term dis-
turbance to intertidal habitat along the shores of the waterway. However,
an equivalent volume of clean sediment will be added to restore the habitat.
The clamshell dredging/nearshore disposal alternative is rated moderate for
short-term protectiveness primarily because some direct worker exposure is
expected during dredging operations. However, worker exposure can be
minimized through the use of protective clothing and other safety-related
gear. The alternatives involving treatment received moderate ratings for
short-term protectiveness because all involve dredged material handling and
long implementation periods, which increase potential worker exposure.
Clamshell dredging/confined aquatic disposal is rated high for short-
term protectiveness. Handling requirements are low, worker and public
exposure can be minimized through the use of safety gears, and adverse
effects to the benthic community at the disposal site are expected to be
short-lived, with re-establishment occurring quickly once the site is capped.
Timeliness--
The no-action and institutional controls alternatives received low
ratings for timeliness. With no action, sediments remain unacceptably
contaminated, source inputs continue, and natural sediment recovery is
unlikely. Source inputs are controlled under the institutional controls
alternative but, as discussed in Section 10.3.2, sediment recovery based on
the indicator contaminants cadmium, lead, and mercury is estimated to be
improbable within 10 yr.
Moderate ratings were assigned to all other alternatives. The Blair
Waterway Slip 1 nearshore disposal site would not be large enough to
accommodate sediment from the head of City Waterway plus sediment from
other problem areas. Therefore, an additional nearshore disposal site would
need to be identified. Likewise, upland or confined aquatic disposal sites
10-36
-------
will also need to be identified. Approval and construction of nearshore,
upland, or confined aquatic disposal sites is estimated to require 1-2 yr.
Long-Term Protectiveness--
The evaluation for long-term protect!veness resulted in low ratings for
the no-action and institutional controls alternatives because the timeframe
for sediment recovery is long. For the latter alternative, the potential
for exposure to contaminated sediments remains, albeit at declining levels
following implementation of source reductions. The observed adverse
biological impacts continue and the potential for impacts through the food
chain remains.
Moderate ratings were assigned to the clamshell dredging/nearshore
disposal and hydraulic dredging/upland disposal alternatives because of the
physicochemical changes that would occur when dredged material is placed in
these disposal facilities. These changes, primarily from new redox
conditions, would tend to increase the migration potential of the inorganic
contaminants. In nearshore facilities, these physicochemical changes can be
minimized by placing sediments below the low tide elevation. Dredged
material testing should provide the necessary data on the magnitude of these
impacts. Although the structural reliability of nearshore facilities is
regarded as good, the nearshore environment is dynamic in nature (i.e., from
wave action and tidal influences). Even though the upland disposal facility
is generally regarded as a more secure option because of improved engineering
controls during construction, there is potential for impacts on groundwater.
The alternative involving solidification received a high rating
primarily because the treatment processes would result in long-term isolation
of the inorganic contaminants. Confined aquatic disposal was also rated
high for long-term protection. Isolation of contaminated material in the
subaquatic environment provides a high degree of protection, with little
potential that sensitive environments will be exposed to sediment con-
taminants. In addition, confined aquatic disposal would maintain physico-
chemical conditions of the contaminated sediments, thereby minimizing
potential contaminant migration.
Reduction in Toxicity, Mobility, or Volume--
Low ratings were assigned to all alternatives under this criterion,
except for solidification. Although, the confined aquatic disposal, upland,
and nearshore disposal alternatives isolate contaminated sediments from the
surrounding environment, the chemistry and toxicity of the material itself
would remain largely unaltered. For nearshore and upland disposal alterna-
tives, the mobilization potential for untreated dredged material may
actually increase with changes in redox potential. Without treatment, the
toxicity of contaminated sediments would remain at preremediation levels.
Contaminated sediment volumes would not be reduced, and may actually
increase with hydraulic dredging options because of suspension of the
material in an aqueous slurry.
10-37
-------
Clamshell dredging with solidification and upland disposal is rated high
for reduction in toxicity, mobility, and volume because inorganic con-
taminants would be immobilized.
Technical Feasibility--
A moderate rating was applied to the option for dredging and confined
aquatic disposal of contaminated sediments at an open-water disposal site,
primarily because placement of dredged and capping materials at depths of
approximately 100 ft would be difficult, although feasible. A moderate
rating was also applied to the alternative involving solidification,
primarily because of the need for bench-scale testing prior to implementa-
tion. Solidification technologies for the treatment of contaminated
dredged material on a large scale are conceptual at this point, although the
method appears to be feasible (Cullinane, J., 18 November 1987, personal
communication).
High ratings were applied to the no-action and institutional controls
alternatives because they can be implemented immediately. High ratings
were also applied to the clamshell dredging/nearshore disposal and hydraulic
dredging/upland disposal alternatives, which can be implemented with readily
available equipment using well established methods.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods are applied for all alternatives. The
intensity of the monitoring effort, which varies with uncertainty about
long-term reliability, does not influence the feasibility of implementation.
Institutional Feasibility--
The no-action and institutional controls alternatives were assigned low
ratings for institutional feasibility because compliance with CERCLA/SARA
mandates would not be achieved. Requirements for long-term protection of
public health and the environment would not be met by either alternative.
Moderate ratings were assigned to the remaining alternatives because of
potential difficulty in obtaining agency approvals for disposal sites or
implementation of treatment technologies. Although several potential
confined aquatic and upland disposal sites have been identified in the
project area, significant uncertainty remains with the actual construction
and development of the sites. The Blair Waterway Slip 1 was assumed to be
available as a nearshore facility, but remains undeveloped and in any case,
would not be large enough to accommodate all sediments from this problem
area and those from other areas. Although excavation and disposal of
untreated, contaminated sediment is discouraged under Section 121 of SARA,
properly implemented confinement should meet requirements for public health
and environmental protectiveness. For the two upland disposal alternatives,
agency approvals are assumed to be contingent upon bench-scale demon-
strations of ability to meet established performance goals (e.g., treat-
10-38
-------
ability of dredge water and immobilization of contaminants through solidifi-
cation) .
Availability--
The no-action and institutional controls alternatives are rated high
for availability. Because of the nature of the no-action and institutional
controls alternatives, equipment and siting availability are not obstacles
to implementation.
Remedial alternatives that include confined aquatic, nearshore, and
upland disposal are rated moderate because of the uncertainty associated
with disposal site availability. Candidate alternatives were developed by
assuming that confined aquatic and upland sites will be available. However,
no sites are currently approved for use and no sites are currently under
construction. Although the Blair Waterway Slip 1 site is assumed to be
available as a nearshore disposal facility, volumes from the head of City
Waterway may exceed its capacity if sediments from other areas are to be
accepted.
Cost--
Capital costs increase with increasing complexity (i.e., from the no-
action to the treatment alternatives). This increase reflects the need to
site and construct disposal facilities, develop treatment technologies, and
implement alternatives requiring extensive contaminated dredged material or
dredge water handling. Costs for hydraulic dredging/upland disposal are sig-
nificantly higher than those for clamshell dredging with either nearshore or
confined aquatic disposal, primarily due to underdrain and bottom liner
installation, dredge water clarification, and use of two pipeline boosters
to facilitate contaminated dredged material transport to the upland site.
The cost of conducting solidification increases as a result of material
costs for the processes, and associated labor costs for material handling
and transport. Dredge water clarification management costs are also
incurred for this alternative. The high cost of site acquisition makes the
cost of nearshore disposal higher than the cost of confined aquatic disposal.
An important component of O&M costs is the monitoring requirements
associated with each alternative. The highest monitoring costs are
associated with alternatives involving the greatest degree of uncertainty
for long-term protectiveness (e.g., institutional controls), or where
extensive monitoring programs are required to ensure long-term performance
(e.g., confined aquatic disposal). Monitoring costs for confined aquatic
disposal are significantly higher than for other options because of the need
to collect sediment core samples at multiple stations, with each core being
sectioned to provide an appropriate degree of depth resolution. Nearshore
and upland disposal options, on the other hand, use monitoring well networks
requiring only the collection of a groundwater sample from each well to
assess contaminant migration.
It is also assumed that the monitoring program will include analyses
for all contaminants of concern (i.e., those exceeding AET values) in the
10-39
-------
waterway. This approach is conservative and could be modified to reflect
use of key chemicals to track performance. Monitoring costs associated with
the treatment alternatives are significantly lower than for other alterna-
tives because the treatment processes reduce the potential for contaminant
migration.
10.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the six sediment remedial alterna-
tives proposed for head of City Waterway, clamshell dredging with confined
aquatic disposal has been recommended as the preferred alternative for
sediment remediation. Because sediment remediation will be implemented
according to a performance-based ROD, the specific technologies identified
in this alternative (i.e., clamshell dredging, confined aquatic disposal)
may not be the technologies eventually used to conduct the cleanup. New and
possibly more effective technologies available at the time remedial activi-
ties are initiated may replace the alternative that is currently preferred.
However, any new technologies must meet or exceed the performance criteria
(e.g., attainment of specific cleanup criteria) specified in the ROD. The
confined aquatic disposal alternative is currently preferred for the
following reasons:
• The alternative protects human health and the environment by
effectively isolating contaminated sediments at near in situ
conditions in a quiescent, subaquatic environment
• Confined aquatic disposal is technically feasible and has
been demonstrated to be effective in isolating contaminated
sediments
• The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 401 and 404 of the Clean Water Act,
and other applicable environmental requirements
• Performance monitoring can be accomplished effectively and
implemented readily
• The volume of contaminated sediment requiring remediation
(approximately 426,000 yd3) is compatible with the available
capacity of the tentatively identified confined aquatic
disposal facilities within the Commencement Bay area
• The sediments in this problem area have high organic carbon
concentrations; placement of these sediments in an oxidizing
environment (present in areas of the nearshore facility above
the water table) would tend to result in acidic conditions,
which in turn could lead to mobilization of metals (U.S. Army
Corps of Engineers 1985)
10-40
-------
• Contaminant concentrations in the sediments are only
moderately elevated over those acceptable for open-water
disposal (PSDDA guidelines); severe water quality impacts due
to dredging and disposal of sediments in water are not
anticipated
• The costs of developing an upland facility that is protective
of groundwater resources are not warranted considering the
levels of contamination and high bulk of sediments in the
mouth of Hylebos Waterway
• Costs are $7 million less than those of the nearshore
disposal alternative and $16 million less than those of the
upland disposal alternative.
Clamshell dredging with confined aquatic disposal is rated high for
long-term protect!veness and moderate for all other criteria, except
reduction in toxicity, mobility, or volume, for which it is rated low.
Implementation of this alternative can be coordinated with similar sediment
remediation activities in Wheeler-Osgood Waterway, and the mouth of Hylebos
Waterway. The alternative is ranked as moderate for short-term protective-
ness because of the potential worker safety hazards and disturbance of
intertidal habitat along the shores of the waterway. This latter dis-
advantage can be offset in the long term through incorporation of a habitat
replacement project in the remedial process. Habitat enhancement is
addressed in part by removing contaminated sediments from the waterway
itself and replacing them with clean sediment. As indicated in Table 10-8,
this alternative also provides a cost-effective means of sediment remedia-
tion.
Although some sediment resuspension is inherent in dredging operations,
silt curtains and other available engineering controls would be expected to
minimize adverse impacts associated with contaminated dredged material
redistribution. Potential impacts on water quality criteria can be predicted
by using data from bench-scale tests to estimate contaminant partitioning to
the water column. Once a disposal site is selected, this alternative can be
implemented over a relatively short timeframe, and seasonal restrictions on
dredging operations to protect migrating anadromous fish are not expected to
pose a problem. Dredging activities within this area are consistent with
the Tacoma Shoreline Management Plan and Sections 404 and 401 of the Clean
Water Act.. Close coordination with appropriate federal, state, and local
regulatory personnel will be required prior to undertaking remedial actions.
The nearshore disposal alternative was not selected because the volume
of material is more compatible with confined aquatic disposal. The Blair
Waterway Slip 1 disposal area is not large enough to accommodate all
contaminated sediments in the Commencement Bay N/T area, nor is it appro-
priate for the contaminants in all sediments. Although confined aquatic
disposal cannot be implemented as quickly as nearshore disposal at an
available site, it offers a similar degree of protection at a lower cost.
10-41
-------
The hydraulic dredging/upland disposal alternative is more costly than
both the confined aquatic and nearshore disposal options, and does not
provide any appreciable benefits over these options. Upland disposal is
therefore not preferred. The solidification/upland disposal alternative was
not selected since the timeframe required for remedial action would be
lengthened. Implementation of this alternative would require bench-scale
and possibly pilot scale testing prior to implementation. In addition,
treatment itself would take a considerable amount of time, given available
treatment equipment and the large volume of contaminated sediments.
Decreased mobility of contaminants due to treatment by stabilization is not
expected to significantly increase long-term protectiveness compared with
confined aquatic disposal. Performance monitoring associated with confined
aquatic disposal would allow early detection of contaminant movement to the
surrounding environment, and corrective actions can be implemented before
adverse effects occur. The solidification/upland disposal alternative has a
cost of over 7 times as great than the confined aquatic disposal alternative.
Expenditure of this additional money does not appear warranted based on the
above discussion.
No-action and institutional controls alternatives are ranked high for
technical feasibility, availability, and capital expenditures. However, the
failure to mitigate environmental and potential public impacts far outweighs
these advantages.
10.7 CONCLUSIONS
The head of City Waterway was identified as a problem area because of
the elevated concentrations of several organic and inorganic contaminants.
HPAH, cadmium, lead, and mercury were selected as indicator chemicals to
assess source control requirements, evaluate sediment recovery, and estimate
the area and volume of sediment to be remediated. In this problem area,
sediments with indicator chemical concentrations currently exceeding long-
term cleanup goals cover an area of approximately 230,000 yd2, with a volume
of 575,000 yd-*- Of the total sediment area currently exceeding long-term
cleanup goals, 59,000 yd2 is predicted to recover within 10 yr following
implementation of known, available, and reasonable source control measures,
thereby reducing the contaminated sediment volume by 149,000 yd3. The total
volume of sediment requiring remediation is, therefore, reduced to
426,000 yd3.
The primary current and historic sources of problem chemicals to the
head of City Waterway include the following:
• Storm drains, particularly drains CN-237, CS-237, CI-225,
CI-230, CI-243, and CI-245
• Martinac Shipbuilding
• Groundwater seepage
• American Plating.
10-42
-------
Source control measures required to correct these problems and ensure
the long-term success of sediment cleanup in the problem area include the
following recent and proposed actions:
• Reduce the amount of metals and hydrocarbons in storm drain
discharge
• Conduct additional source identification to identify sources
of groundwater contamination, and implement control tech-
nologies if necessary
• Conduct additional investigation of the American Plating
facility and implement control technologies if necessary
• Confirm that all significant sources of problem chemicals
have been identified and controlled
• Implement regular sediment monitoring to confirm sediment
recovery predictions and assess the adequacy of source
control measures.
In general, it should be possible to control sources sufficiently to
maintain acceptable long-term sediment quality. This determination was made
by comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. Source control requirements were developed through application
of the sediment recovery model for the indicator chemicals HPAH, cadmium,
lead, and mercury. If the potentially responsible parties demonstrate that
implementation of all known, available, and reasonable control technologies
will not provide sufficient reduction in contaminant loadings, then the area
requiring sediment remediation may be re-evaluated.
Clamshell dredging with confined aquatic disposal was recommended as the
preferred alternative for remediation of sediments not expected to recover
within 10 yr following implementation of all known, available, and reasonable
source control measures. The selection was made following a detailed
evaluation of viable alternatives encompassing a wide range of general
response actions. Because sediment remediation will be implemented
according to a performance-based ROD, the alternative eventually implemented
may differ from the currently preferred alternative. The preferred
alternative meets the objective of providing protection for both human
health and the environment by effectively isolating contaminated sediments
at near in situ conditions in a quiescent, subaquatic environment. Confined
aquatic disposal has been demonstrated to be effective in isolating
contaminated sediments (U.S. Army Corps of Engineers 1988). The alternative
is consistent with the Tacoma Shoreline Management Plan, Sections 404 and
401 of the Clean Water Act, and other applicable environmental requirements.
As indicated in Table 10-8, clamshell dredging with confined aquatic
disposal provides a cost-effective means of sediment remediation. The
estimated cost to implement this alternative is $3,372,000. Environmental
monitoring and other O&M costs at the disposal site have a present worth of
10-43
-------
$485,000 for a period of 30 yr. These costs include long-term monitoring
of sediment recovery areas to verify that source control and natural
sediment recovery have corrected the contamination problems in the recovery
areas. The total present worth cost of the preferred alternative is
$3,857,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control
Limited information
associated costs.
on disposal site availability and
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures
• Final selection of a disposal site.
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
and regulations, utilize permanent solutions to the maximum extent prac-
ticable, and are cost-effective.
10-44
-------
11.0 WHEELER-OSGOOD WATERWAY
Potential remedial actions are defined and evaluated in this section
for the Wheeler-Osgood Waterway problem area. The waterway is described in
Section 11.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 11.2 provides an overview of contaminant
sources, including site background, identification of known and potential
contaminant reservoirs, remedial activities, and current site status. The
effects of source control measures on sediment contamination are discussed
in Section 11.3. Areas and volumes of sediments requiring remediation are
discussed in Section 11.4. The detailed evaluation of the candidate
sediment remedial alternatives chosen for the problem area and indicator
problem chemicals is provided in Section 11.5. The preferred alternative is
identified in Section 11.6. The rationale for its selection is presented,
and the relative merits and deficiencies of the remaining alternatives are
discussed. The discussion in Section 11.7 summarizes the findings of the
selection process and integrates required source control with the preferred
remedial alternative.
11.1 WATERWAY DESCRIPTION
Wheeler-Osgood Waterway branches off of City Waterway approximately
midway along its eastern side (Figure 11-1). Formed prior to 1894 from the
old western channel of the Puyallup River (Tetra Tech 1986c), the waterway
is ringed by abandoned buildings, warehouses, and several small industries.
Wheeler-Osgood Waterway is privately owned and is not regarded as a
navigable channel. Water depths in the waterway are generally less than
10 ft, and width ranges from approximately 65 ft at the head to approximately
100 ft at the mouth, where the channel intersects City Waterway.
11.1.1 Nature and Extent of Contamination
Analysis of data collected during the RI/FS in conjunction with
historical data has revealed extensive organic and inorganic contamination
in Wheeler-Osgood Waterway (Tetra Tech 1985a, 1986c). The highest levels of
organic enrichment found within Commencement Bay Nearshore/Tideflats (N/S)
area sediments were observed here. Total organic carbon concentrations of
10-18 percent were detected, and TOC was identified as a Priority 2 contami-
nant in the waterway (Tetra Tech 1986c). Other organic contaminants, all of
which were classified as Priority 2, include LPAH, HPAH, biphenyl, phenol,
4-methy1 phenol, 1,2-dichlorobenzene, and N-nitrosodiphenylamine. HPAH was
selected as an indicator of hydrocarbon contamination originating from
several potential nonpoint sources (see Section 11.2). Estimated areal and
depth distributions of HPAH are illustrated in Figure 11-2. Elevated
concentrations of HPAH were observed throughout the central portion of the
waterway, and surficial HPAH contamination exceeded the long-term cleanup
11-1
-------
1 PUGET SOUND PLYWOOD
2 -0" STREET PETROLEUM FACILITIES
3 -D" STREET PETROLEUM FACILITIES .MULTIPLE OWNERS!
4 COAST CRAFT
5 PICK FOUNDRY
6 GERRISH BEARING
7 OLYMPIC CHEMICAL
8 GLOBE MACHINE
9 PUGET SOUND HEAT TREATING.
10 MARINE IRON WORKS
11 WOODWORTH & COMPANY
12 WESTERN DRY KILN
13 WESTERN STEEL FABRICATORS
14 OLD ST. REGIS DOOR MILL (CLOSED)
15 KLEEN BLAST
16 NORTHWEST CONTAINER
17 RAINIER PLYWOOD
18 MARTINAC SHIPBUILDING
19 CHEVRON
20 HYGRADE FOODS
21 TAR PITS SITE (MULTIPLE OWNERS)
22 WEST COAST GROCERY
23 PACIFIC STORAGE
24 MARINA FACILITIES
25 EMERALD PRODUCTS
26 PICKERING INDUSTRIES
27 UNION PACIFIC & BURLINGTON NORTHERN RAILROADS
28 PCKS COVE BOAT SALES AND REPAIRS
PICKS COVE MARINA
29 AMERICAN PLATING
30 INDUSTRIAL RUBBER SUPPLY
31 TOTEM MARINE
32 COAST IRON MFG.
33 MSA SALTWATER BOATS
34 CUSTOM MACHINE MFG.
35 WESTERN FISH
36 OLD TACOMA LIGHT
37 COLONIAL FRUIT » PRODUCE
38 J.D.ENGLISH STEEL CO.
39 JOHNNY'S SEAFOOD
40 CASCADE DRYWALL
41 SCOFIELD. TRU-MIX, N. PACIFIC PLYWOOD (CLOSED)
42 PACIFIC COAST OIL
43 CITY WATERWAY MARINA
44 J.H. GALBRAITH CO.
45 HARMON FURNITURE
46 TACOMA SPUR SITE
Reference: Tacoma-Pierce County Health
Department (1984,1966).
Notes: Property boundaries are approximate
baaed on aerial photographs and drive-
by inspections.
46
Figure 11-1.
Wheeler-Osgood Waterway - Existing businesses
and industries.
11-2
-------
HPAH (ng/kg)
§ § § § § § § § § § §
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
RATIO TO CLEANUP GOAL
0.2-
0.4 H
0.6-
&
3
0.8-
1.0-
1.2
I—CW-92
CW-91-
-. CW-91
- CW-92
MEAN LOWER LOW WATER
FEAStBLITY STUDY SEDIMENT
PROFILE SURVEYS (1906)
SEDWENT SURVEYS CONDUCTED
IN 1964
SEDMENT SURVEYS CONDUCTED
BEFORE 1864 (1979-1081)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
WHEELER- °4
OSGOOD
Figure 11 -2. Areal and depth distributions of HPAH in sediments
of Wheeler-Osgood Waterway, normalized to long-term
cleanup goal.
11-3
-------
goal of 17,000 ug/kg at two stations in the waterway. The sediment core
profiles shown in Figure 11-2 indicate that high concentrations of HPAH were
present to depths of approximately 0.5 yd. The fact that contamination was
detected at depth in two cores separated by a considerable distance within
the problem area suggests that the subsurface contamination is not localized.
Zinc, copper, lead, and cadmium were also observed at high concen-
trations in Wheeler-Osgood Waterway (Tetra Tech 1985a, 1986c). Metals
evaluated during the RI were relatively uniformly distributed throughout the
waterway (Tetra Tech 1985a) and all were identified as Priority 2 contami-
nants. Total metals concentrations based on the sum of maximum observed
concentrations for lead, zinc, and copper were less than 2,000 mg/kg in the
waterway. Zinc was selected as an indicator of metals contamination.
Estimated areal and depth distributions of zinc are shown in Figure 11-3.
Concentrations of zinc exceeding the cleanup goal of 410 mg/kg extend over
the eastern two-thirds of the problem area. Depth profiles obtained from
the two core sampling stations suggest that metals contamination exceeds the
cleanup goal to depths of approximately 0.5 yd, with the highest concentra-
tions occurring at the head of the waterway and declining towards the mouth.
11.1.2 Recent and Planned Dredging Pro.iects
The U.S. Army Corps of Engineers has not recently received any appli-
cations for dredging permits in Wheeler-Osgood Waterway, nor does the Port
of Tacoma have any existing dredging plans.
11.2 POTENTIAL SOURCES OF CONTAMINATION
This section provides an overview of the sources of contamination to
the sediments of Wheeler-Osgood Waterway and a summary of available loading
information for the contaminants of concern. The only potential source of
contaminants that has been identified is storm drain runoff (Table 11-1).
The Wheel er-Osgood drain (CW-254) is the largest storm drain discharging
into Wheeler-Osgopd Waterway (Figure 11-4). It drains an area of approxi-
mately 80 ac adjacent to the head of Wheeler Osgood Waterway. Annual
runoff from the CW-254 drainage basin is estimated at 160 ac-ft/yr
(0.2 ft3/sec), based on an average rainfall of 37 in (Norton and Johnson
1985a) and a runoff coefficient of 0.7. Industries currently active in the
drainage basin include Hyqrade Foods, Rainier Plywood, Kleen Blast, Northwest
Container, and Chevron (see Nos. 20, 17, 15, 16, and 19, respectively in
Figure 11-1). Discharge from CW-254 consists of stormwater runoff and
noncontact cooling water from Hygrade Foods, the only NPDES-permitted
industry in the basin.
Hygrade Foods is allowed to discharge a maximum of 190,000 gal/day
(0.3 ft'/sec) of noncontact cooling water to drain CW-254. The permit
requires monitoring of total oil and grease and pH. During a site inspection
of Hygrade Foods in October 1987, Ecology staff observed minor problems and
found that the facility's drainage characterization was inadequate.
11-4
-------
ZINC (mg/kg)
0 200 400 600 BOO 1000
0 1 2
RATIO TO CLEANUP GOAL
0.2-
0 4-
0.6-
UJ
Q
0.8-
1.0-
1.2-1
CW-92
CW-91 1
CW-»1
CW-92
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEQUENT
PROFILE SURVEYS (1966)
SEGMENT SURVEYS CONDUCTED
IN 1964
SEGMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1961)
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
300
WHEELER
OSGOOD
Figure 11 -3. Area! and depth distributions of zinc in sediments
of Wheeler-Osgood Waterway, normalized to long-term
cleanup goal.
11-5
-------
TABLE 11-1. WHEELER-OSGOOD WATERWAY - SOURCE STATUS3
Chemical /Group
Total organic carbon
Total volatile solids
Grease and oil
LPAH
HPAH
Biphenyl
Phenol
Zinc
^ Copper
i Lead
<* Cadmium
1 , 2-Di chl orobenzene
4 Methyl phenol
N-nitrosodlphenylamine
Chemical
Pr1or1tyb
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Sources
Storm drains, mainly
at head of Wheel er-
Osgood
Chevron
Storm drains
Ubiquitous oil spills
Marina fires
Storm drains
Unknown
Carstens Packing
House and Hygrade
Food
TacoM Tar Pitt
Unknown
Source ID
Yes
Potential
Yes
Potential
Potential
Yes
No
Potential
Potential
Potential
No
Source Loading
Yes
No
Yes
No
No
Yes
No
No
No
No
No
Source Status
Ongoing
Ongoing
Ongoing
Ongoing, sporadic
Historical
Ongoing
Unknown
Historical
Historical
Ongoing
Sediment Profile Trends
No clear trend
Variable; general surface minima
Fairly constant over surface
15 cm. Slight surface minima
for lead at one station
Pronounced surface minimum
Surface minimum
Surface maxima
a Source Information and sediment information blocks apply to all chemicals In the
respective group, not to individual chemicals only.
b For Priority 3 chemicals, the station exceeding AET is noted in parentheses.
-------
HHi ROW
IMIIII SURF«CEOfVUN
19^ OUIFMlANOOnWINIMER
—•- R.owo«ECTicm
«»»
SEE noont 10 7 FOB DHAHAGE BASM
n*l*f*nc« horn laconu Pvfa Counlr H«aWi D«p«1rn«n41196J)
Figure 11-4. Surface water drainage pathways to Wheeler-Osgood
Waterway.
-------
Reissuance of the facility's permit was delayed until these deficiencies
could be corrected (Morrison, S.( 22 January 1988, personal communication).
In the past, storm drain CW-254 received untreated industrial wastes
from Carsten's Packing Company. A slaughterhouse and meat packing plant,
Carsten's was bought by Hygrade Foods in about 1960. The direct discharge
of process wastes to CW-254 was discontinued around 1970, when Hygrade began
discharging wastes to the city sanitary sewer system. However, because of
unidentified cross-connections between the process effluent and the cooling
water/storm drain system, some discharge of process waste to CW-254 continued
until at least the mid-1970s (Tetra Tech 1985a).
Historical loading of contaminants into storm drain CW-254 may also
have occurred from the Chevron property. Dames & Moore (1982) reported the
occurrence of numerous spills onsite, noting that the historical method of
dispersing oil was to dig holes in the sand and allow seepage into underlying
soils. These waste materials were probably picked up in area drains and
discharged to the waterway via CW-254.
Other storm drains discharging into Wheeler-Osgood Waterway are
relatively minor, functioning primarily as roof and parking lot drains from
adjacent property (Figure 11-4). Descriptions of these storm drains are
provided in Table 11-2.
Ecology recently conducted a survey of storm drains in Wheeler-Osgood
Waterway (Stinson and Norton 1987c). Grab samples were collected from 4 of
the 11 drains in the waterway (i.e., CW-252, CW-254, CW-257, and CW-261)
during a single rainfall event of 0.15 in. The remainino storm drains could
not be sampled because of negligible flows. At 0.4 ft-Vsec, the Wheeler-
Osgood drain (CW-254) accounted for more than 95 percent of the total storm
drain flow measured during the sampling event. Flow in the other three
drains ranged from 0.001 fwsec to 0.006 ft-Vsec. Contaminants frequently
detected in the storm drain discharges include metals (arsenic, copper,
lead, and zinc), pentachlorophenol, PAH, and phthalates. Phenol, 2-methyl-
phenol, and 4-methylphenol were detected only in drain CW-261.
In October 1986, the City of Tacoma began monitoring effluent quarterly
from several drains in the tideflats area, including CW-254. Copper
concentrations in particulate matter from CW-254 effluent have consistently
been greater than the long-term sediment cleanup goals in the three data sets
currently available. Cadmium, lead, nickel, mercury, zinc, LPAH and HPAH
concentrations were greater than the long-term cleanup goals in most samples
collected (Getchell, C., 12 October -1987, 18 December 1987, 8 February
1988, and 19 August 1988, personal communications). The comparison of storm
drain particulate matter with cleanup goals assumes no mixing of sediments
with cleaner material from other sources, and provides a worst-case analysis
of the impact of storm drain discharge on sediment quality in the waterway.
The available data indicate that CW-254 is the major source of metals
loadings from surface runoff to Wheeler-Osgood Waterway. However, the
relatively large loadings are primarily a function of flow. Metals
concentrations observed in CW-254 discharges were consistently lower than
11-8
-------
TABLE 11-2. STORM DRAINS DISCHARGING
INTO WHEELER-OSGOOD WATERWAY
Drain
Number Description Use
250 18-in open channel Stormwater runoff from roof drain and
paved area at JD English Steel
18-in concrete pipe Runoff from parking lot at JD English
steel
251 24-in concrete pipe Unknown
252 6-in PVC pipe Runoff from parking lot at Cascade
Drywall, Inc.
253 6-in concrete pipe Runoff from parking lot at General Beer
Distributors
254 30-in corrugated steel Largest drain in waterway. Serves area
between Portland Avenue and the head of
Wheeler-Osgood Waterway. Also receives
NPDES-permitted noncontact cooling water
discharge from Hygrade Foods.
255 2-in iron pipe No longer operational
256 6-in concrete pipe Major drain for yard area
4-in iron pipe
12-in concrete
257 18-in concrete pipe Unknown
258 Series of pipes Roof drains for Waddles Company building
259 12-in concrete pipe Unknown
260 8-in concrete pipe Runoff from paved area at Western Steel
Fabricators
261 12-in steel pipe Unknown
Reference: Hanowell, R., 9 April 1986, personal communication.
11-9
-------
the concentrations measured in other storm drain discharges to Wheeler-
Osgood Waterway. Metals concentrations in all storm drains sampled were
generally within the range typical of urban runoff, suggesting that metals
may originate from nonpoint sources rather than a specific contaminant
source.
Sources of HPAH to Wheeler-Osgood Waterway are not as well defined.
HPAH concentrations in particulate matter from CW-254 was measured above the
long-term cleanup goal of 17,000 ug/kg in five of six samples collected.
under the City of Tacoma's storm drain sampling program (Getchell, C.,
12 October 1987, 18 December 1987, 8 February 1988, and 19 August 1988,
personal communications). However, sediment samples from around this drain
did not reveal concentrations above the cleanup goal. Data for HPAH from
cores collected during the RI (Tetra Tech 1985a) and this study indicate
that contaminant concentrations generally increased with depth. This depth
distribution suggests that the major sources of HPAH are probably historic.
Summary loading tables for Priority 2 contaminants of concern for
Wheeler-Osgood Waterway (i.e., cadmium, copper, lead, zinc, LPAH, HPAH,
phenol, biphenyl, 1,2 dichlorobenzene, 4-methylphenol, and N-nitrosodi-
phenylamine) are provided in Appendix E. These tables reflect post-RI
(Tetra Tech 1985a, 1986c) loading data for the following drains: CW-252,
CW-254, CW-257, and CW-261 (Stinson and Norton 1987c). However, the
information provided in Appendix E does not include recent data from the
City of Tacoma storm drain monitoring program. (Flows were not measured for
storm drain CW-254 in that study.)
11.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the potential success of source control was
evaluated. This evaluation was based on contaminant concentrations and
assumptions regarding the relationship between sources and sediment
contamination. Included within the evaluation was an estimate of the degree
of source control needed to correct existing sediment contamination problems
over the long term.
11.3.1 Feasibility of Source Control
Stormwater runoff from the Wheeler-Osgood drain (CW-254) and 10 smaller
storm drains is the primary source of contamination in Wheeler-Osgood
Waterway. Storm drain CW-254 has been identified as the major source of
metals. It is one of five major storm drains included in the storm drain
monitoring program being implemented by the City of Tacoma. The sources of
HPAH appear to be largely historical, although HPAH is present in particulate
matter from CW-254 effluent.
11-10
-------
Available technologies for controlling surface water runoff are
summarized in Section 3.2.2, including methods for retaining runoff onsite
(e.g., berms, channels, grading, sumps) and revegetation or paving to reduce
erosion. Contaminated storm water can also be treated during or after
collection in a drainage system. For example, sedimentation basins,
vegetation channels, and grassy swales can significantly reduce concentra-
tions of particulate matter and their associated contaminants.
Implementation of these measures should result in a significant
reduction in contaminant discharges. Given the contaminant types, nonpoint
nature of sources, and available control technologies, it is estimated that
implementation of all known, available, and reasonable control technologies
will reduce contaminant loadings by up to 70 percent. This level of source
control is assumed to be feasible for both indicator chemicals (zinc and
HPAH). This estimate is based on the assumption that control of contaminants
entering or discharging from Wheeler-Osgood drain (CW-254) could be
implemented.
11.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals noted above. Complete results are
reported in Tetra Tech (1987a). A summary of those results is presented in
this section.
The depositional environment in Wheeler-Osgood Waterway has not been
well characterized. A sedimentation rate of 375 mg/cnr/yr (0.31 cm/yr) and
a mixing depth of 10 cm were considered representative of this problem area.
The sedimentation rate was estimated from a 210-Pb profile collected from
the waterway. Losses due to biodegradatipn and diffusion were determined to
be negligible for these chemicals. Two indicator chemicals (i.e., HPAH and
zinc) were used to evaluate the effect of source control and the degree of
source control required for sediment recovery. Two timeframes were
considered: a reasonable timeframe (defined as 10 yr) and the long term.
The source loadings of indicator chemicals in Wheeler-Osgood Waterway are
assumed to be in steady-state with sediment accumulation. Results of the
source control evaluation are summarized in Table 11-3.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times at the locations
with the highest concentrations are predicted to be 51 yr for HPAH and 23 yr
for zinc. These estimates are based on the highest zinc and HPAH concentra-
tions measured in Wheeler-Osgood Waterway sediments. Sediment recovery is
not predicted in a reasonable timeframe (i.e., 10 yr).
11-11
-------
TABLE 11-3. WHEELER-OSGOOD WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
Zinc HPAH
Station with Highest Concentration
Station identification CW-91 CI
Concentration3 773 81,700
Enrichment ratio** 1.9 4.8
Recovery time if sources are
eliminated (yr) 23 51
Percent source control required
to achieve 10-yr recovery NPC NPC
Percent source control required
to achieve long-term recovery 47 79
Average of Three Highest Stations
Concentration3 677 36,850
Enrichment ratiob 1.7 2.2
Percent source control required
to achieve long-term recovery 39 54
10-Yr Recovery
Percent source control assumed
feasible 70 70
Highest concentration recovering
in 10 yra 492 20,900
Highest enrichment ratio of sediment
recovering in 10 yr 1.2 1.2
a Concentrations in ug/kg dry weight for organics, mg/kg dry weight for
metals.
b Enrichment ratio is the ratio of observed concentration to cleanup goal.
c NP = Not possible.
11-12
-------
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source control
is expected to reduce source input by 70 percent for HPAH and zinc. With
this level of source control as an input value, the model predicts that
sediments with an enrichment ratio of 1.2 or lower for both zinc and HPAH
will recover within 10 yr (see Table 11-3). An enrichment ratio of 1.2 cor-
responds to a sediment concentration of 492 mg/kg for zinc and 20,900 ug/kg
for HPAH. The surface area of sediments not recovering to the long-term
cleanup goal within 10 yr is shown in Figure 11-5. For comparison, sediments
currently exceeding long-term cleanup goals for the indicator chemicals are
also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that 39 percent of the zinc and 54 percent of the
HPAH inputs must be eliminated to maintain acceptable contaminant concentra-
tions in freshly deposited sediments (see Table 11-3). These estimates are
based on the average of the three highest enrichment ratios for the indicator
chemicals. These values are presented for comparative purposes; the actual
percent reduction required in source loading is subject to considerable
uncertainty in the assumptions of the predictive model. These ranges
probably represent upper limit estimates of source control requirements
since the assumptions incorporated into the model are considered to be
environmentally protective.
Based on four measurements by the City of Tacoma (Getchell, C.,
12 October 1987, 18 December 1987, 8 February 1988, personal communications),
average reductions of 67 percent for zinc and 79 percent for HPAH would be
necessary to achieve the cleanup goals in particulate matter from storm
drain CW-254. Data on particulate matter composition are not available for
the other storm drains in Wheeler-Osgood Waterway. However, storm drain
CW-254 appears to be the major source of contaminants to the waterway.
11.3.3 Source Control Summary
The major ongoing sources of metals and HPAH to Wheeler-Osgood Waterway
are storm drains. From available data, it appears that, of the storm drains
discharging to the waterway. CW-254 is the major source of contaminants. If
contaminant loadings are completely eliminated (100 percent source control),
then it is predicted that sediment concentrations of zinc in the surface
mixed layer will decline to the long-term cleanup goal of 410 mg/kg in 23 yr
and that concentrations of HPAH will decline to the long-term cleanup goal of
17,000 ug/kg in 51 yr. Sediment remedial action will therefore be required
to mitigate the observed and potential adverse biological effects within a
reasonable timeframe.
Substantial levels of source control will also be required to ensure
that acceptable sediment quality is maintained after sediment cleanup. The
estimated percent reduction in source loadings required for long-term
maintenance is 39 percent for zinc and 54 percent for HPAH. Limited data
obtained by the City of Tacoma indicate that for storm drain CW-254 average
11-13
-------
AT PRESENT
IN10YR
Wheeler-Osgood Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA (yd2)
VOLUME (yd3 )
IN10YR
DEPTH (yd)
AREA (yd2)
VOLUME (yd3 )
05
22,000
11.000
0.5
22,000
11,000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
HPAH (AET = 17,000 (ig/kg)
ZINC (AET = 410 mg/kg)
Figure 11 -5. Sediments in Wheeler-Osgood Waterway not meeting cleanup goals for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
reductions of 67 percent for zinc and 79 percent for HPAH would be necessary
to reduce particulate matter concentrations to sediment long-term cleanup
goal levels.
Implementation of all known, available, and reasonable control technolo-
gies is expected to provide approximately a 70 percent reduction in
contaminant loading to the waterway. Therefore, it appears that by
implementing feasible levels of source control sediment cleanup goals can be
maintained following sediment remedial action in Wheeler-Osgood Waterway.
11.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with zinc or HPAH concentrations
exceeding long-term cleanup goals is approximately 11,000 yd3 (see
Figure 11-5). This volume was estimated by multiplying the area! extent of
sediment exceeding the cleanup goal (22,000 yd2) by the estimated 0.5-yd
depth of contamination (see contaminant sediment profiles in Figures 11-2
and 11-3). The estimated thickness of contamination is only an approxima-
tion, since only two sediment profiles were collected.
The total estimated volume of sediments with zinc or HPAH concentrations
that are still expected to exceed long-term cleanup goals 10 yr foil owing
implementation of feasible levels of source control is 11,000 yd3. This
volume was estimated by multiplying the areal extent (i.e., 22,000 yd2) of
sediment contamination with enrichment ratios greater than 1.2 (see
Table 11-3) by the estimated 0.5-yd depth of contamination. This quantity of
sediment (11,000 yd3) was used to evaluate alternatives and to identify the
preferred alternatives.
11.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
11.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion, this set of alternatives is
evaluated to determine the suitability of each alternative for the remedia-
tion of contaminated sediments in Wheeler-Osgood Waterway. Remedial
measures address the 11,000 yd3 of contaminated sediments that are expected
to exceed long-term cleanup goals in 10 yr. The objective of this evaluation
is to identify the alternative considered preferable to all others based on
CERCLA/SARA criteria of effectiveness, implementability, and cost.
An assessment of the applicability of each alternative to remediation
of contaminated sediments in Wheeler-Osgood Waterway is required. Site-
specific characteristics that must be considered in such an assessment
include the nature and extent of contamination; the environmental setting;
the location of potential disposal sites; and site physical properties such
as waterway usage, bathymetry, and water flow conditions. Alternatives that
are determined to be appropriate for the waterway can then be evaluated
based on the criteria presented in Chapter 4.
11-15
-------
The indicator chemicals HPAH and zinc were selected to represent inputs
from the storm drains, which are the primary source of contamination to the
waterway (see Table 11-1). Areal distributions for both indicators are
presented in Figure 11-5 to indicate the degree to which contaminant groups
overlap based on long-term cleanup goals and estimated 10-yr sediment
recovery. The high organic matter content of Wheeler-Osgood Waterway
sediments in conjunction with the extensive HPAH contamination suggest that
a treatment process for organics could be an appropriate component of
remedial action. Total concentrations of metals in the waterway, which are
generally less than 2,000 mg/kg, are not expected to limit the applicability
of solvent extraction, thermal treatment, or land treatment. The alterna-
tives incorporating these treatment processes are evaluated for Wheeler-
Osgood Waterway. Solidification is less likely to be successful because of
the high concentrations of total organic carbon and other organic con-
taminants, and is therefore not evaluated.
It is assumed that the requirements to maintain navigational access to
the Puyallup River and Sitcum Waterway could preclude the use of a hydraulic
pipeline for nearshore disposal at the Blair Waterway disposal site.
Therefore, clamshell dredging has been chosen for evaluation in conjunction
with the nearshore disposal alternative.
Nine of the ten sediment remedial alternatives are evaluated below for
the cleanup of Wheeler-Osgood Waterway:
• No action
• Institutional controls
• In situ capping
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solvent extraction/upland disposal
• Clamshell dredging/incineration/upland disposal
• Clamshell dredging/land treatment.
These candidate alternatives are described in detail in Chapter 3.
11.5.2 Evaluation of Alternatives
The three primary evaluation criteria are effectiveness, implement-
ability, and cost. A narrative matrix summarizing the assessment of each
alternative based on effectiveness and implementability is presented in
Table 11-4. A comparative evaluation of alternatives based on ratings of
11-16
-------
| EFFECTIVENESS 1
SHORT-TERM PROTECTIVENESS 1
TIMELINESS
LONG-TERM PROTECTIVENESS
(CONTAMINANT
MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY. AND
VOLUME
TABLE 11-4.
NO ACTION
NA
NA
Original contamination remains.
Source inputs continue. Ad-
verse biological impacts con-
tinue.
Sediments are unlikely to recov-
er In the absence of source con-
trol. This alternative is ranked
ninth overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxicity and contam-
inant mobilty are expected to
remain at current levels or
Increase as a result of continued
source Inputs. Contaminated
sediment volume Increases as
a result of continued source
Inputs.
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
, There are no elements of insti-
* tutional control measures that
have the potential to cause
harm during implementation.
Source control is Implemented
and would reduce sediment con-
tamination with time, but adverse
impacts would persist in the in-
terim.
Access restrictions and moni-
toring efforts can be Implement-
ed quickly. Partial sediment re-
covery is achieved naturally,
but significant contaminant
levels persist This alternative
is ranked eighth overall for
timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via Ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity is unaffected.
REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE WHEELER-OSGOOD WATERWAY PROBLEM AREA
IN SITU
CAPPING
Community exposure is not a
concern in the implementation
of this alternative. COM expo-
sure and handling are minimal.
contaminated sediments.
Contaminant redistribution is
minimized. Existing contami-
nated habitat Is destroyed and
replaced with clean material.
Rapid recolonization is expected
In situ capping can be Implement-
ed quickly. Pre-implementation
testing and modeling may be nec-
essary, but minimal time is requir-
ed. Equipment is available. Dis-
posal site development should
not delay implementation. This
alternative is ranked first for
timeliness.
The long-term reliability of ttie
cap to prevent contaminant re-
exposure in the absence of
physical disruption Is consider-
ed good.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota. Protection is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment.
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in
situ conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure Is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic dredg-
ing. Removal with dredge and
disposal with downpipe and dif-
fuser minimizes handling require-
ments. Workers wear protective
gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment with
low particle affinity is resus-
pended during dredging opera-
tions. Benthic habitat is impact-
ed at the disposal site.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked
third overall for timeliness.
The long-term reliability of Ihe
cap to prevent contaminant re-
exposure in a quiescent, sub-
aquatic environment is consi-
dered acceptable.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota. Protection is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in
situ conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM to a barge offshore during
transport. Public access to
dredge and disposal sites is re-
stricted. Public exposure po-
tential is low.
creases exposure potential
moderately over hydraulic
dredging. Workers wear pro-
tective gear.
Existing contaminated habitat
Is destroyed but recovers* rapid-
ly. Nearshore intertidal habitat
is lost. Contaminated sediment
is resuspended.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment is available. Disposal site
development should not delay
implementation. This alternative
is ranked second for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by Isolating COM.
Varying physicochemical con-
ditions In the fill may increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment. The
potential for contaminant migra-
tion into marine environment
may Increase over CAD. Adja-
cent fish mitigation site is sen-
sitive area. Nearshore site is
dynamic in nature.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. Altered
conditions resulting from
dredge/disposal operations
may increase mobility of metals.
Volume of contaminated sedi-
ments Is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM is confined to a pipeline
during transport. Public access
to dredge and disposal sites Is
restricted. Exposure from COM
spills or mishandling is possible
but overall potential is tow.
COM to a pipeline during trans-
port. Dredge water contamina-
tion may 'increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed but recovers rapid-
ly. Contaminated sediment with
low particle affinity is resus-
pended during dredging opera-
tions. Dredge water can be
managed to prevent release of
soluble contaminants.
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked fourth
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Oike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM. Al-
though the potential for ground-
water contamination exists, It is
minimal. Upland disposal facili-
ties are more secure than near-
shore facilities.
Upland disposal is secure, with
negligible potential for environ-
mental impact if properly de-
signed. Potential for shallow
groundwater contamination
exists.
The toxicity of COM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may increase due to resuspen-
sion of sediment.
CLAMSHELL DREDGE/
SOLVENT EXTRACTION
UPLAND DISPOSAL
Public access to dredge, treat-
ment, and disposal sites Is re-
stricted. Extended duration of
treatment operations may resul
In moderate exposure potential.
Additional COM handling asso-
ciated with treatment Increases
worker risk over dredge/disposal
options. Workers wear protec-
tive gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations.
Bench and pilot scale testing
are required. Full scale equip-
ment is available. Once approv-
al is obtained, treatment should
be possible within 2 years. This
alternative is ranked fifth over-
all for timeliness.
Treated COM low in metals can
be used as inert construction
material or disposed of at a
standard solid waste landfill.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA approved
treatment or disposal. Perma-
nent treatment for organic con-
taminants Is effected.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA approved
treatment or disposal. Residual
contamination is reduced below
harmful levels.
Harmful contaminants are re-
moved from COM. Concen-
trated contaminan s are dis-
posed of by RCRA approved
treatment or disposal. Toxicity
and mobility considerations are
eliminated. Volume of contami-
nated material Is substantially
reduced.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment, and disposal sites is re-
stricted. Extended duration of
treatment operations may resul
in moderate exposure potential
pllshed over an extended period
of time thereby increasing ex-
posure risks. Workers wear pro
tecttve gear.
Existing contaminated habitat
is destroyed by dredging but re-
covers rapidly. Sediment is re-
suspended during dredging op-
erations. Process controls are
required to reduce potential air
emissions.
Substantial COM testing and
incinerator installation time is
required before a thermal treat-
ment scheme can be imple-
mented. Once approval is ob-
tained, treatment should be pos-
sible within 2 years. This alter-
native is ranked sixth overall for
timeliness.
Treated COM low in metals can
be used as inert construction
material or disposed of at a
standard solid waste landfill.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals may have leaching poten-
tial. Volume of contaminated ma-
terial Is substantially reduced.
CLAMSHELL DREDGE/
LAND TREATMENT
Public access to dredge and dis-
posal sites is restricted. Clam-
shell dredging, land transport,
and extended duration of treat-
ment operations In open environ-
ment raise exposure risks.
Land treatment of COM Is ac-
complished over an extended
period of time. COM is tilled Into
the treatment soil. Exposure
potential decreases with time as
degradation occurs.
Existing contaminated habitat
is destroyed by dredging but re-
covers rapidly. Sediment Is re-
suspended during dredging op-
erations. Dredge water manage-
ment needs are minimal. Contam
inant has relatively high solubil-
ity which enhances its potential
for migration from treatment site.
Substantial testing would be re-
quired to insure that contaminants
can be degraded and to determine
optimal operating conditions.
Treatment would probably require
a demonstration project, a long
treatment period, and a closure
phase. This alternative is ranked
seventh overall for timeliness.
Liner, run-on, and runoff controls
reliable. Potential system failure
becomes less critical with time,
as treatment progresses.
There is potential for public
health impacts as a result of
contaminant migration from
treatment facility. COM is not
confined.
Design features of land treat-
ment system preclude contami-
nant migration to groundwater or
surface water. Control of vola-
tile emissions is limited.
Treatment of degradable organic
compounds eliminates this
component of COM toxlcrty.
Metals are not treated. Mobility
of metals may be enhanced by
aerobic soil conditions.
11-17
-------
| IMPLEMENTABILITY |
TECHNICAL FEASIBILITY
INSTITUTIONAL FEASIBILTY
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 11-4. (CONTINUED)
NO ACTION
Implementation of this alterna-
tive is feasible and reliable.
No monitoring over and above
programs established under
other authorities Is Implemented.
There are no O 4 M requirements
associated with the no action
alternative.
This alternative Is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the Intent of CERCLA/
SARA and NCP because of on-
going Impacts.
All materials and procedures are
available.
* INSTITUTIONAL
CONTROLS
*
Source control and Institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be identified.
Sediment monitoring schemes
can be readily Implemented.
'Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
.Some O & M Is associated with
monitoring, maintenance of
warning signs, and Issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels in sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
impacts. State requirements
" for source control are achieved.
Coordination with TPCHD tor
health advisories for seafood •
consumption is required.
All materials and procedures are
available to implement institu-
tional controls.
IN SITU
CAPPING
Clamshell dredges and diffuser
pipes are conventional and reli-
able equipment. In situ capping
Is a demonstrated technology.
Confinement reduces monitoring
requirements in comparison to
Institutional controls. Sediment
monitoring schemes can be
readily Implemented.
O & M requirements are minimal.
Some O & M is associated with
monitoring for contaminant mi-
gration and cap Integrity.
Approvals from federal, state,
and local agencies are feasible.
WISHA/OSHA worker protection
is required. Substantive as-
pects of CWA and shoreline
management programs must be
addressed. This alternative
compiles with U.S. EPA's onsite
disposal policy.
Equipment and methods to Im-
plement this alternative are
readily available.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment
Is reliable. Placement of dredge
and capping materials difficult,
but feasible. Inherent difficulty
in placing dredge and capping
materials at depths of 100 ft or
greater.
Confinement reduces monitoring
requirements In comparison to
institutional controls. Sediment
monitoring schemes can be
readily Implemented.
O & M requirements are minimal.
Some O & M Is associated with
monitoring for contaminant mi-
gration and cap Integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Availability of open
water CAD sites is uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Moni-
toring Implementability Is en-
hanced compared with CAD.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facil-
ity siting are assumed feasible.
However, disposal of untreated
COM Is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been iden-
tified and is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
Is reliable. Secure upland con-
finement technology Is well de-
veloped.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring over CAD. Installa-
tion of monitoring systems Is
routine aspect of facility siting.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Coordination is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
COM is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
piles with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLVENT EXTRACTION
UPLAND DISPOSAL
Although still In the develop-
mental stages, sludges, soils,
and sediments have success-
fully been treated using this
technology. Extensive bench-
arid pilot-scale testing are likely
to be required.
Monitoring Is required only to
evaluate the reestablishmem
of benthlc communities. Moni-
toring programs can be readily
implemented.
No O & M costs are Incurred at
the conclusion of COM treat-
ment. System maintenance is
Intensive during implementation.
Approvals depend largely on re-
sults of pilot testing and the na-
ture of treatment residuals.
WISHA/OSHA wortier protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Complies with policies for
permanent reduction in contami-
nant mobility. Requires RCRA
permit for disposal of concen-
trated organic waste.
Process equipment available.
Disposal site availability is not a
primary concern because of re-
duction in hazardous nature of
material.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Incineration systems capable of
handling COM have been de- -
veloped, but no applications in-
volving COM have been report-
ed. Effects of salt and moisture
content must be evaluated. Ex-
tensive bench- and pilot-scale
testing are likely to be required.
Disposal site monitoring Is not
required if treated COM is deter-
mined to be nonhazardous. Air
quality monitoring is intensive
during implementation.
No O & M costs are incurred at
the conclusion of COM treat-
ment System maintenance Is
intensive during implementation.
Approvals for incinerator opera-
tion depend on pilot testing and
ability to meet air quality stan-
dards.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Complies with policies for
permanent reduction in contami-
nant toxitity and mobility. Re-
quires compliance with PSAPCA
standards.
Incineration equipment can be
installed onsite for COM re-
mediation efforts. Applicable
incinerators exist Disposal site
availability is not a concern be-
cause of reduction In hazardous
nature of material.
CLAMSHELL DREDGE/
LAND TREATMENT
Land treatment is a demon-
strated technology for materials
contaminated with degradable
organic compounds. Extensive
bench- and pilot-scale testing
are nkely to be required.
Monitoring programs can be
readily Implemented. Extensive
monitoring is required during
active treatment period, with
less required during closure.
O & M consists of maintaining
monitoring equipment, optimal
soil conditions, tilling equipment,
and groundskeeping. Site in-
spections are required.
Treatment facility siting and
operation require extensive
agency review prior to approval.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's policy for toxldty
reduction and onsite disposal.
Availability of land treatment
site Is uncertain.
11-18
-------
high, moderate, and low in the various subcategories of evaluation criteria
is presented in Table 11-5. For effectiveness, the subcategories are short-
term protectiveness; timeliness; long-term protectiveness; and reduction in
toxicity, mobility, or volume. For implementability, the subcategories are
technical feasibility, institutional feasibility, availability, capital
costs, and O&M costs. Remedial costs are shown for sediments currently
exceeding long-term cleanup goal concentrations and also for sediments that
would still exceed the cleanup goal concentrations 10 yr after implementing
feasible source controls (i.e., 10-yr recovery costs).
Short-Term Protectiveness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no action and institutional controls because the adverse
biological and potential public health impacts continue with the contaminated
sediments remaining in place. Source control measures initiated as part of
the institutional controls would result in reduced sediment contamination
with time but adverse impacts would persist in the interim. It is predicted
that, even with complete source elimination, reduction in sediment concentra-
tions to acceptable levels will require 23 yr for zinc and 51 yr for HPAH
(see Table 11-3).
With the exception of clamshell dredging/confined aquatic disposal and
hydraulic dredging/upland disposal, other alternatives involving sediment
remediation are rated moderate. With in situ capping the contaminated
sediments are left in place, which eliminates the potential for direct
public or worker exposure; however, some intertidal habitat could be lost.
The clamshell dredging/nearshore disposal alternative is rated moderate for
short-term protectiveness primarily because some direct worker exposure is
expected during dredging operations. Alternatives involving treatment
received moderate ratings from short-term protectiveness because, as
compared with nontreatment alternatives, all involve more dredged material
handling, longer implementation periods and increased air emissions, which
increase potential worker exposure. The risks inherent to the solvent
extraction and incineration treatment processes themselves are also
considered.
The clamshell dredging/confined aquatic disposal and hydraulic
dredging/upland disposal alternatives are rated high for short-term
protectiveness. For clamshell dredging/confined aquatic disposal, handling
requirements are low, worker and public exposure can be minimized through
the use of safety gear, and adverse effects to the benthic community at the
disposal site are expected to be short-lived, with re-establishment
occurring quickly once the site is capped. Upland disposal involves the use
of land generally considered to be a less valuable resource than the
intertidal areas which would be used for nearshore disposal.
Timeliness--
The no-action, institutional controls, and land treatment alternatives
received low ratings for timeliness. With no action, sediments remain
unacceptably contaminated, source inputs continue, and natural sediment
11-19
-------
TABLE 11-5. EVALUATION SUMMARY FOR WHEELER-OSGOOD WATERWAY
No Action
Short-Term
Protectiveness Low
Timeliness .Low
Long-Term
Protectiveness Low
Reduction in Toxicity,
Mobility, or Volume Low
Technical Feasibility High
Institutional
Feasibility Low
Availability' High
Long-Term Cleanup
Goal Cost*
. Capital
O&M
Total
Long-Term Cleanup
Goal with 10-yr
Recovery Cost*
Capital
O&M
•Total
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
283
289
6
283
289
' In Situ
Capping
Moderate
High
Moderate
Low
High
Moderate
High
144
252
396
144
252
396
Clamshell/
CAD
High
Moderate
High
Low
Moderate
Moderate
Moderate
139
,31
170
139
31
170,
Clamshell/
Nearshore
Disposal
Moderate
High
Moderate
Low
High
Moderate
High
321
31
352
321
31
352
Hydraulic/
Upland
Di sposal
High
Moderate
Moderate
Low,
High
Moderate
Moderate
504
39
543
504
-39
543
Clamshell/
Extraction/
Upland
Disposal
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
2,377
38
2,415
2,377
38
2,415
Clamshell/
Incinerate/
Upland
Disposal
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
5,337
, 38
5,375
5,377
38
5,375
Cl amshel 1 /
1 Land
Treatment
Moderate
Low
Moderate
Moderate
Moderate
Low
Low
606
86
692
606
86
692
All costs are in $1,000.
-------
recovery is unlikely. Source inputs are controlled under the institutional
controls alternative but as discussed in Section 11.3.2, sediment recovery
based on the indicator contaminants zinc and HPAH is estimated to be
improbable within 10 yr. Land treatment would probably require a demonstra-
tion project, a relatively long treatment period, and a closure phase.
Approval and siting considerations are likely to adversely affect the
timeliness of this alternative.
Moderate ratings were assigned to the remaining treatment alternatives
and to the dredge alternatives involving upland and confined aquatic
disposal. Approvals and construction of upland or confined aquatic disposal
sites is estimated to require 1-2 yr. Equipment and methods used require no
development period, and pre-implementation testing is not expected to be
extensive. These conditions suggest that the upland disposal alternatives
can be accomplished in a much shorter period of time than if treatment is
involved. The solvent extraction and incineration alternatives are likely
to require a period of extensive testing before being accepted. However,
once approval is obtained, treatment of the contaminated sediments in
Wheeler-Osgood Waterway should be possible within less than 1 yr, assuming
maximum treatment rates of 420 yd3/day (see Section 3.1.5).
The in situ capping and nearshore disposal alternatives are rated high
for timeliness. Pre-implementation testing and modeling may be necessary to
evaluate the potential for contaminant releases resulting from dredging and
from contaminant migration through the cap, but such testing is not expected
to require an extensive period of time. Equipment and methods are readily
available, and nearshore disposal siting issues are less likely to delay
implementation than for alternatives involving upland and confined aquatic
disposal.
Long-Term Protectiveness--
The evaluation for long-term protectiveness resulted in low ratings for
the no-action and institutional controls alternatives because the timeframe
for sediment recovery is long. For the latter alternative, the potential
for exposure to contaminated sediments remains, albeit at declining levels
following implementation of source reductions. The observed adverse
biological impacts continue and the potential for impacts through the food
chain remains.
In situ capping received a moderate rating for long-term protectiveness
because it could result in a long-term reduction in intertidal habitat.
Moderate ratings have been assigned to the clamshell dredging/nearshore and
hydraulic dredging/upland disposal alternatives because of the physico-
chemical changes that would occur when dredged material is placed in these
disposal facilities. These changes, primarily from new redox conditions,
would tend to increase the migration potential of the inorganic contaminants.
However, dredged material testing should provide the necessary data on the
magnitude of these impacts. These physicochemical changes can be minimized
in a nearshore facility by placement of sediments below the low tide
elevation. Although the structural reliability of the nearshore facilities
is regarded as good, the nearshore environment is dynamic in nature (i.e.,
11-21
-------
from wave action and tidal influences). Even though the upland disposal
facility is generally regarded as a more secure option because of improved
engineering controls during construction, there is potential for impacts on
groundwater resources.
Alternatives involving treatment all received moderate ratings primarily
because the treatment processes would result in the destruction of organic
but not inorganic contaminants. In the solvent extraction and incineration
alternatives, the treated solids would be confined in a standard landfill,
assuming that the material is considered nonhazardous. In the case of land
treatment, metals would be immobilized in the soil.
Confined aquatic disposal is rated high for long-term protection.
Isolation of contaminated material in the subaquatic environment provides a
high degree of protection, with little potential for exposure of sensitive
environments to sediment contaminants. In addition, confinement under in
situ conditions maintains physicochenrical conditions of the contaminated
sediments, thereby minimizing potential migration of metal contaminants.
Reduction in Toxicity, Mobility, or Volume--
Low ratings have been assigned to all alternatives under this criterion,
except the three involving treatment. Although capping, confined aquatic
disposal, upland, and nearshore disposal alternatives isolate contaminated
sediments from the surrounding environment, the chemistry and toxicity of
the material itself would remain largely unaltered. For nearshore and
upland disposal alternatives, the mobilization potential for untreated
dredged material may actually increase with changes in redox potential.
Without treatment, the toxicity of contaminated sediments would remain at
preremediation levels. Contaminated sediment volumes would not be reduced,
and may actually increase with hydraulic dredging options because the
material would be suspended in an aqueous slurry.
Alternatives involving treatment would destroy organic contaminants,
but remain ineffective for the treatment of metal contaminants. Therefore,
treatment alternatives received moderate ratings. The solvent extraction
process would change the chemical status of the metals by providing the
alkaline conditions necessary for formation of insoluble hydroxides. As
long as the pH of the solid residue remained approximately neutral or
alkaline, the mobility of the metals would remain reduced. Incineration may
increase the mobility of metals in the treated solids. In land treatment,
the cation exchange capacity of the soil would immobilize metals, but the
potential for long-term leaching of the metals would remain.
Technical Feasibility--
Alternatives involving treatment received moderate ratings for the
criterion of technical feasibility because the treatment processes have never
been applied to sediment remediation. All processes are believed to be
suitable for this application, but lack of experience and demonstrated
performance in the use of these processes for treatment of contaminated
dredged material warrants caution. Extensive bench- and pilot-scale testing
11-22
-------
are likely to be required before treatment via solvent extraction, incinera-
tion, or land treatment could be implemented. A moderate rating has also
been applied to the clamshell dredging/confined aquatic disposal option.
Placement of dredged and capping materials at depths of approximately 100 ft
is difficult, although feasible. Considerable effort and resources may be
required to monitor the effectiveness and accuracy of dredging, disposal,
and capping operations.
High ratings are warranted for alternatives not involving treatment
(except confined aquatic disposal) because the equipment, technologies, and
expertise required for implementation have been developed and are readily
accessible. The technologies constituting these alternatives have been
demonstrated to be reliable and effective in the past for similar operations.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods are applied for all alternatives. The
intensity of the monitoring effort, which varies with-uncertainty about
long-term reliability, does not influence the feasibility of implementation.
Institutional Feasibility--
The no-action and institutional controls alternatives were assigned low
ratings for institutional feasibility because compliance with CERCLA/SARA
mandates would not be achieved. Requirements for long-term protection of
public health and the environment would not be met by either alternative.
The land treatment alternative also received a low rating because of the
difficulty associated with siting the facility and fulfilling permitting
requirements.
Moderate ratings were assigned to the remaining alternatives because of
potential difficulty in obtaining agency approvals for disposal sites or
implementation of treatment technologies. Although several potential
confined aquatic and upland disposal sites have been identified in the
project area, significant uncertainty remains with the actual construction
and development of the sites. It is assumed that Blair Waterway Slip 1 can
be used as a nearshore facility, although the site remains undeveloped at
this time. Although excavation and disposal of untreated, contaminated
sediment is discouraged under Section 121 of SARA, properly implemented
confinement should meet requirements for public health and environmental
protectiveness. Agency approvals are assumed to be contingent upon a bench-
scale demonstration of effectiveness of the alternative in meeting esta-
blished performance goals (e.g., treatability of dredge water).
Availability— . .. -
Sediment remedial alternatives that can be implemented using existing
equipment, expertise, and disposal or treatment facilities were ratedrhigh
for availability. The no-action, institutional controls, in situ capping,
and nearshore disposal alternatives can be readily implemented. Because of
the nature of the no-action and institutional controls alternatives,
11-23
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equipment and siting availability are not obstacles to implementation.
Disposal site availability is not an obstacle to implementation of the
capping alternative since capping would be performed on sediments in place.
The nearshore disposal alternative was rated high because of the availability
of Blair Waterway Slip 1 as a disposal site.
Remedial alternatives that include confined aquatic and upland disposal
were rated moderate because of the uncertainty associated with disposal site
availability. Candidate alternatives were developed by assuming that
confined aquatic and upland sites will be available. However, no sites are
currently approved for use and no sites are currently under construction.
The sediment treatment alternatives, which include solvent extraction and
incineration, were rated moderate for availability since some degree of
difficulty in obtaining necessary equipment is expected. In addition, a
location for disposal of treatment residuals will be needed.
The availability of a land treatment site suitable for the treatment of
contaminated dredged material was considered as being more uncertain than for
confined aquatic or upland disposal sites. This uncertainty is primarily
due to the large land area requirements associated with land treatment.
Therefore, land treatment received a low rating for the availability
criterion.
Cost--
Capital costs increase with increasing complexity (i.e., from no action
to the treatment alternatives). This increase reflects the need to site and
construct disposal facilities, develop treatment technologies, and implement
alternatives requiring extensive contaminated dredged material or dredge
water handling. Costs for hydraulic dredging/upland disposal are signifi-
cantly higher than those for clamshell dredging with either nearshore or
confined aquatic disposal, primarily due to underdrain and bottom liner
installation, dredge water clarification, and use of two pipeline boosters
to facilitate contaminated dredged material transport to the upland site.
The cost of conducting the treatment alternatives increases as a result of
material costs for the processes, and associated labor costs for material
handling and transport. Dredge water clarification management costs are
also incurred for those alternatives. A major element in the land treatment
cost is land acquisition.
An important component of O&M costs is the monitoring requirements
associated with each alternative. The highest monitoring costs are
associated with alternatives involving the greatest degree of uncertainty
for long-term protect!veness (e.g., institutional controls), or where
extensive monitoring programs are required to ensure long-term performance
(e.g., confined aquatic disposal). Monitoring costs for confined aquatic
disposal are significantly higher than for other options because of the need
to collect sediment core samples at multiple stations, with each core being
sectioned to provide an appropriate degree of depth resolution. Nearshore
and upland disposal options, on the other hand, use monitoring well networks
requiring only the collection of a single groundwater sample from each well
to assess contaminant migration.
11-24
-------
It is also assumed that the monitoring program will include analyses
for all contaminants of concern (i.e., those exceeding long-term cleanup
goals) in the waterway. This approach is conservative and could be modified
to reflect use of key chemicals to track performance. Monitoring costs
associated with the treatment alternatives are significantly lower than for
other alternatives because the treatment processes reduce the potential for
contaminant migration.
11.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the nine sediment remedial
alternatives proposed for Wheeler-Osgood Waterway, clamshell dredging with
confined aquatic disposal has been recommended as the preferred alternative
for sediment remediation. Because sediment remediation will be implemented
according to a performance-based ROD, the specific technologies identified
in this alternative (i.e., clamshell dredging, confined aquatic disposal)
may not be the technologies eventually used to conduct the cleanup. New and
possibly more effective technologies available at the time remedial
activities are initiated may replace the alternative that is currently
preferred. However, any new technologies must meet or exceed the performance
criteria (e.g., attainment of specific cleanup criteria) specified in the
ROD. This currently preferred alternative offers a high degree of long-term
protection of public health and the environment in that it isolates
contaminated dredged material at a remote site well below tidal influence.
Implementation can be coordinated with similar sediment remediation
activities in the head of City Waterway. The confined aquatic disposal
alternative was recommended for these problem areas for the reasons
provided in Section 10.6. The alternative is ranked as moderate for short-
term protectiveness because intertidal habitat will be disturbed. This
disadvantage can be offset in the long term by incorporating a habitat
replacement project in the remedial process. This goal is addressed in part
by removing contaminated sediments from the waterway and replacing them with
clean sediment. As indicated in Table 11-5, this alternative provides a
cost-effective means of sediment remediation. The total costs of the
confined aquatic disposal alternative ($170,000) are approximately 50 percent
of the nearshore disposal alternative, which has the next lowest cost.
Although some sediment resuspension is inherent in dredging operations,
silt curtains and other available engineering controls would be expected to
minimize adverse impacts associated with contaminated dredged material
redistribution. Potential impacts on water quality can be predicted by
using data from bench-scale tests to estimate contaminant partitioning to
the water column. Once a disposal site is selected, this alternative can be
implemented over a relatively short timeframe. Seasonal restrictions on
dredging operations to protect migrating anadromous fish are not expected to
pose a problem. Dredging activities within this problem area are consistent
with the Tacoma Shoreline Management Plan and Sections 404 and 401 of the
Clean Water Act. Close coordination with appropriate federal, state, and
local regulatory personnel will be required prior to undertaking remedial
actions.
11-25
-------
Of the remaining alternatives, clamshell dredging with nearshore
disposal in Blair Waterway Slip 1 is feasible, as are the treatment alterna-
tives. However, nearshore disposal would not take advantage of the same
procedures as those used for the preferred alternative in the head of City
Waterway (i.e., dredging with confined aquatic disposal). The treatment
options are considered too costly, given the limited amount of additional
protection they would provide. In situ capping has been eliminated because
of the shallow depths and potential destruction of nearshore habitat.
No-action and institutional controls alternatives are rated high for
technical feasibility, availability, and capital expenditures. However, the
failure to mitigate environmental and potential public impacts far outweighs
these advantages.
11.7 CONCLUSIONS
Wheeler-Osgood Waterway was identified as a problem area because of the
elevated concentrations of several inorganic and organic compounds. HPAH
and zinc were selected as indicator chemicals to assess source control
requirements, evaluate sediment recovery, and estimated the area and volume
to be remediated. In this problem area, sediments with concentrations
currently exceeding long-term cleanup goals cover an area of approximately
22,000 yd2, and a volume of 11,000 yd3. Of the total sediment area currently
exceeding cleanup goals, none is predicted to recover within 10 yr following
implementation of all known, available, and reasonable source control
measures. The total volume of sediment requiring remediation is, therefore
11,000 yd3.
The primary identified sources of problem chemicals to the Wheeler-
Osgood Waterway are storm drains. Source control measures required to
correct these problems and ensure the long-term success of sediment cleanup
in the problem area include the following actions:
• Control problem chemicals (metals and hydrocarbons) discharg-
ing to the waterway through storm drains
• Confirm that all sources of problem chemicals have been
identified and controlled
• Conduct routine sediment monitoring to confirm sediment
recovery predictions and successful implementation of source
control measures.
It should be possible to control sources sufficiently to maintain
acceptable long-term sediment quality. This determination was made by
comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. Source control requirements were developed through application
of the sediment recovery model for the indicator chemicals HPAH and zinc.
If the potentially responsible parties demonstrate that implementation of
all known, available, and reasonable control technologies will not provide
11-26
-------
sufficient reduction in contaminant loadings, then the area requiring
sediment remediation may be re-evaluated.
Clamshell dredging with confined aquatic disposal was recommended as the
preferred alternative for remediation of sediments not expected to recover
within 10 yr following implementation of all known, available, and reasonable
source control measures. The selection was made following a detailed
evaluation of viable alternatives encompassing a wide range of general
response actions. Because sediment remediation will be implemented
according to a performance-based ROD, the alternative eventually implemented
may differ from the currently preferred alternative. The preferred
alternative meets the objective of providing protection for both human
health and the environment by effectively isolating contaminated sediments
at near in situ conditions in a quiescent, subaquatic environment. Confined
aquatic disposal has been demonstrated to be effective in isolating
contaminated sediments (U.S. Army Corps of Engineers 1988). The alternative
is consistent with the Tacoma Shoreline Management Plan, Sections 404 and
401 of the Clean Water Act, and other applicable environmental requirements.
As indicated in Table 11-5, clamshell dredging with confined aquatic
disposal provides a cost-effective means of sediment mitigation. The
estimated cost to implement this alternative is $139,000. Environmental
monitoring and other O&M costs at the disposal site have a present worth of
$31,000 for a period of 30 yr. These costs include long-term monitoring of
sediment recovery areas to verify that source control and natural sediment
recovery have corrected the contamination problems in the recovery areas.
The total present worth cost of preferred alternative is $170,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control
• Limited information on disposal site availability and
associated costs.
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
11-27
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• Monitoring of sources and sediments to verify the effective-
ness of source control measures
• Final selection of a disposal site.
Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
and regulations, utilize the most protective solutions to the maximum extent
practicable, and are cost-effective.
11-28
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12.0 MOUTH OF CITY WATERWAY
Potential remedial actions are defined and evaluated in this section
for the mouth of City Waterway problem area. The waterway is described in
Section 12.1. This description includes a discussion of the physical
features of the waterway, the nature and extent of contamination observed
during the RI/FS field surveys, and a discussion of anticipated or proposed
dredging activities. Section 12.2 provides an overview of contaminant
sources including site background, identification of known and potential
contaminant reservoirs, remedial activities, and current site status. The
effects of source control measures on sediment contaminant concentrations
are discussed in Section 12.3. Area and volume of sediments requiring
remediation are discussed in Section 12.4. The detailed evaluation of the
candidate sediment remedial alternatives chosen for the problem area and
indicator problem chemicals is provided in Section 12.5. The preferred
alternative is identified in Section 12.6. The rationale for its selection
is presented, and the relative merits and deficiencies of the remaining
alternatives are discussed. The discussion in Section 12.7 summarizes the
findings of the selection process and integrates required source control
with the preferred remedial alternative.
12.1 WATERWAY DESCRIPTION
The problem area designated as the mouth of City Waterway extends from
the mouth at the confluence with Commencement Bay to the llth Street Bridge,
approximately 3,500 ft from the mouth. City Waterway is a designated
navigational channel that was first bulwarked against erosion and dredged to
accommodate ship traffic in approximately 1890 (Tetra Tech 1986c). The
waterway was most recently dredged by the U.S. Army Corps of Engineers in
1948. An illustration of the waterway and the locations of nearby industries
is presented in Figure 12-1. This portion of the waterway is approximately
3,500 ft long and 750 ft wide. Totem Marina extends nearly 300 ft into the
waterway on the west side, which greatly reduces the actual navigable
portion (Tetra Tech 1985b). The depth of this portion of the waterway
increases from the llth Street Bridge to the mouth. Subbottom profiling of
this area showed mid-channel depths ranging from 30 ft below MLLW at the
bridge to 35 ft below MLLW at the mouth (Raven Systems and Research 1984).
Profiling revealed that sediment accumulation in the navigation channel
ranges in depth from 1 to 4 ft, with a cross section near the bridge showing
a fairly uniform soft sediment layer 2-3 ft thick (Tetra Tech 1985b).
Sediments within the waterway are typically 64 percent fine-grained material
(range of 28-83 percent) with an average clay content of 18 percent.
12.1.1 Nature and Extent of Contamination
An examination of sediment contamination data obtained during the RI/FS
sampling efforts (Tetra Tech 1985a,b, 1986c) and historical data has
revealed that sediments in the mouth of City Waterway contain concentrations
12-1
-------
1 PUGET SOUND PLYWOOD
2 -D-STREET PETROLEUM FACILITIES
3 "D' STREET PETROLEUM FACILITIES (MULTIPLE OWNERS)
4 COAST CRAFT \
5 PICK FOUNDRY
6 GERRISH BEARING
7 OLYMPIC CHEMICAL
8 GLOBE MACHINE
9 PUGET SOUND HEAT TREATING
10 MARINE IRON WORKS
11 WOODWORTH & COMPANY
12 WESTERN DRY KILN
13 WESTERN STEEL FABRICATORS
14 OLD ST REGIS DOOR MILL (CLOSED)
15 KLEEN BLAST
16 NORTHWEST CONTAINER
17 RAINIER PLYWOOD
18 MARTINAC SHIPBUILDING
19 CHEVRON
20 HYGRADE FOODS
21 TAR PITS SITE (MULTIPLE OWNERS)
22 WEST COAST GROCERY
23 PACIFIC STORAGE
24 MARINA FACILITIES
25 EMERALD PRODUCTS
26 PICKERING INDUSTRIES
27 UNION PACIFIC 4 BURLINGTON NORTHERN RAILROADS
28 PICKS COVE BOAT SALES AND REPAIRS
PCKS COVE MARINA
29 AMERICAN PLATING
30 INDUSTRIAL RUBBER SUPPLY
31 TOTEM MARINE
32 COAST IRON MFG.
33 MSA SALTWATER BOATS
34 CUSTOM MACHINE MFG.
35 WESTERN FISH
36 OLD TACOMA LIGHT
37 COLONIAL FRUIT & PRODUCE
38 J.D.ENGLISH STEEL CO.
39 JOHNNY'S SEAFOOD
40 CASCADE DRYWALL
41 SCOFIELD. TRU-MIX, N. PACIFIC PLYWOOD (CLOSED)
42 PACIFIC COAST OIL
43 CITY WATERWAY MARINA
44 J H GALBRAITH CO.
45 HARMON FURNITURE
46 TACOMA SPUR SITE
Reference: Taooma-Pierce County Health
Department (1984, 1966).
Notes: Property boundaries are approximate
based on aerial photographs and drive-
by inspections.
27
46
30
meters
200
Figure 12-1. Mouth of City Waterway - Existing industries and
businesses.
12-2
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of organic contaminants that are harmful to benthic organisms. No Priority 1
contaminants were identified in the waterway. However, LPAH and HPAH were
identified as Priority 2 contaminants. The following organic and inorganic
compounds exceeded their corresponding AET value at only one station sampled
and are therefore considered Priority 3 contaminants: dibenzothiophene,
phenol, biphenyl, zinc, mercury, and PCBs.
HPAH has been selected as an indicator chemical at the mouth of City
Waterway to represent numerous potential hydrocarbon contamination sources.
The Priority 3 contaminant mercury was selected as an indicator representa-
tive of the erratically distributed inorganic compounds in the problem area.
The areal and depth distributions of HPAH are illustrated in
Figure 12-2. HPAH concentrations exceeded the long-term cleanup goal of
17,000 ug/kg at only two stations. The sediment core profile for HPAH did
not fall within the area determined to exceed cleanup goals, but was
adjacent to a small problem area (Figure 12-2). A trend of erratic vertical
distribution in the upper 0.8 yd was observed with a subsurface maximum
apparent.
The areal and depth distributions of mercury are illustrated in
Figure 12-3. The mercury concentration exceeded the cleanup goal of
0.59 mg/kg at only one surface sampling station, where a concentration of
0.60 mg/kg was observed. As shown in Figure 12-3, the concentration of
mercury exceeded the cleanup goal at an adjacent station by a factor of more
than 3 at a depth of 0.5 yd. Mercury concentrations appeared to fluctuate
randomly in mid-channel stations (Tetra Tech 1986c). Data derived from the
sediment core profile revealed a definite surface minimum suggesting that
inputs have decreased over time. Based on the mercury core profile,
contamination was assumed to extend to a depth of 1 yd.
12.1.2 Recent and Planned Dredging Pro.iects
The U.S. Army Corps of Engineers has not recently received any appli-
cation for dredging permits. The Port of Tacoma does not plan to dredge in
the mouth of City Waterway.
12.2 POTENTIAL SOURCES OF CONTAMINATION
Several businesses and industries surround the mouth of City Waterway.
Fick Foundry, present as early as 1920; Globe Machine; Olympic Chemical;
and the D Street petroleum facilities are located along the east bank.
Portions of the D Street tank farms have been present since the 1920s.
Totem Marina occupies most of the west bank. The most significant potential
sources of contamination to the head of City Waterway are the D Street
petroleum storage facilities. Approximately 22 storm drains that discharge
into the problem area are also potential sources of contamination
(Figure 12-4). Contaminants may also enter the mouth of the waterway from
sources in the head of the waterway and Wheeler-Osgood Waterway, which are
discussed in Sections 10.2 and 11.2, respectively. Irregular spills from
marinas along the west bank of the waterway are considered a less important
12-3
-------
HPAH
2.000 4 000
6.000
8.000
0-
0.2-
0.4 -
0.6-
0.8-
| 1.0
X 1.2-
0.
g 1.4
1.6
1.8-
2.0-
2.2-
2.4-
0 0.1 02 0.3 0.4
RATIO TO CLEANUP GOAL
CI-92
MOUTH OF CITY
CI-92
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDMENT SURVEYS CONDUCTED
IN 1964
SEDMENT SURVEYS CONDUCTED
BEFORE 1964 (1978-1981)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
Figure 12-2. Area! and depth distributions of HPAH in sediments
at the mouth of City Waterway, normalized to long-term
cleanup goal.
12-4
-------
MERCURY (mo/kg)
0 0.4 08 12 It 2.0 2.4
I ' ' I ' ' I ' ' 'I ' ' 'l
01234
RATIO TO CLEANUP GOAL
0.2-
0.4-
0.8-
1.0-
1.2 J
CI-92
MOUTH OF CITY
CI-92
MEAN LOWER LOW WATER
FEASBLITY STUDY SEDIMENT
PROFILE SURVEYS (19865
SEDMENT SURVEYS CONDUCTED
IN 1984
SEDMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
Figure 12-3. Area! and depth distributions of mercury in sediments
at the mouth of City Waterway, normalized to long-term
cleanup goal.
12-5
-------
ro
f
!•»- OUTFWlANODfUMNUtOER
—— FlOWOCflECTIOM
CP «»•
* SEE FIQUfC 10 7 FOR ORUMOE BASM
H»l«f«no» from Taoonw Ptorc* CotfMy H«tftti D«fMrtm«n« II9B3)
Figure 124 Surface water drainage pathways to the mouth
of City Waterway.
-------
source of contamination. Table 12-1 provides a summary of problem chemical
and source status information for the head of City Waterway.
12.2.1 D Street Petroleum Storage Facilities
Site Background--
The D Street petroleum storage facilities are located along the
northeastern shore of City Waterway. Bulk petroleum storage and distribution
facilities are located in this area, including a subsurface pipeline owned by
Olympic Pipeline Company. Currently, storage tanks used by Union Oil, Mobil
Oil, and Shell Oil are located at the site. Globe Machine, located in the
immediate vicinity, is not engaged in petroleum operations. Portions of the
storage facilities have been present at the site since the 1920s.
The petroleum products managed at the D Street facilities include fuel
oil, diesel fuel, leaded gasoline, and unleaded gasoline. Product leakage and
spills have led to contamination of groundwater, and free product continues
to be found in monitoring wells onsite (Johnson and Norton 1985a; Hart-
Crowser & Associates 1987a). Intermittent seepage of petroleum product along
the City Waterway embankment adjacent to the site has been observed for the
past 17 yr. Product and contaminated groundwater removed from wells onsite
contain one-, two-, and three-ring aromatic compounds, including alkylated
derivatives. Low concentrations of phenol and cresols have also been
detected (Johnson and Norton 1985a).
Identification of Contaminant Reservoirs Onsite--
Petroleum product from accidental spills and pipeline leakage percolates
through the soil and accumulates on the water table (Hart-Crowser
& Associates 1987a). The hydraulic gradient in the aquifer slopes toward the
waterways on both sides of the peninsula on which the tank farms are
situated. Thus free product and product constituents that have been
partitioned into groundwater eventually migrate to the waterways. The
groundwater flow rate in the contaminated aquifer has been estimated at
1-15 ft/yr (Hart-Crowser & Associates 1987a). Because surface soils at the
site are contaminated with petroleum product, stormwater runoff is another
potential pathway of contamination to the mouth of City Waterway.
Johnson and Norton (1985a) sampled water from two wells on the D Street
site and determined that the major contaminants were the single-ring
aromatics benzene, ethylbenzene, toluene, and total xylenes at concentrations
ranging from 1 to 30 mg/L. Naphthalene, 2-methylnaphthalene, and phenan-
threne were found in the well water but the higher molecular weight PAH were
noticeably absent even with the low detection limits (1-5 ug/L) achieved in
the analysis. Phenol and cresols were detected at concentrations below
1 mg/L. Overlying free product sampled from one of the wells contained
appreciable quantities of the single-ring aromatics found in the underlying
water. Phenanthrene was not detected in the free product at a detection
limit of 200 mg/L.
12-7
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TABLE 12-1. MOUTH OF CITY WATERWAY - SOURCE STATUS3
Chemical /Group
LPAII
IIPAH
Di benzothiophene
Phenol
Biphenyl
Zinc
Meri.ury
PCBs
Chemical
Priorityb
2
2
3 (CI-20)
3 (CI-20)
3 (CI-20)
3 (CI-05)
3 (CI-20)
3 (historical )
Sources
0 St. petro. facility
Storm drains
Ubiquitous oil spills
Marina fires
Storm drains
Unknown
Source ID
Potential
Yes
Potential
Potential
Yes
No
Source Loading
No
Yes
No
No
Yes
No
Source Status
Ongoing
Ongoing
Ongoing, sporadic
Historical
Ongoing
Historical
Sediment Profile Trends
Erratic; no clear trend
Fairly constant over upper
50 cm. Mercury has surface
minimum.
Surface minimum
ro
00
a Source information and sediment information blocks apply to all chemicals in the
respective group, not to individual chemicals only.
For Priority 3 chemicals, the station exceeding AET is noted in parentheses.
-------
In sediment samples removed from City Waterway adjacent to the site,
the single-ring aromatics were not detected, but appreciable concentrations
of unsubstituted high molecular weight PAH were found. Absence of the
single-ring aromatics in the sediments is not surprising in view of their
volatility and susceptibility to microbiological degradation. That the PAH
in the sediments were generally unsubstituted suggests that the source of
the PAH is not a fossil fuel but is derived from combustion. Thus despite
unequivocal visual evidence that petroleum product from the D Street
facilities is present along the City Waterway embankment, there is little
evidence of a linkage between contaminants of concern at the mouth of the
Waterway, namely PAH, and constituents of free product and contaminated
groundwater underneath the site.
Recent and Planned Remedial Activities--
Efforts to recover lost product have been made by facility owners.
Mobil Oil is reportedly still operating, at least intermittently, an inter-
ceptor drain installed in 1970-71 along its property next to City Waterway.
In 1984, Shell Oil installed a recovery system on property now owned by Globe
Machine and Manufacturing Company. Shell reportedly has also pumped free
product from individual onsite wells. In 1985, Mobil Oil installed a recovery
well and has successfully recovered product from it.
Despite these measures, Hart-Crowser & Associates (1987a) report that
the extent and thickness of free product on the groundwater table has been
increasing over the years. Without additional control measures or more
effective use of existing recovery systems, the seepage of petroleum product
into City Waterway may be expected to continue.
The following litigative considerations apply to the D Street petroleum
storage operations:
• Globe Machine and Manufacturing, which purchased property
from Shell Oil, initiated legal action against a group of oil
companies for petroleum product contamination beneath its
property (Reale, D., 17 September 1987, personal communica-
tion) .
• A consent order has been initiated by Ecology to prepare a
work plan for remedial action at the site. The plan should
include additional subsurface product analyses and possibly
some offshore sediment analyses. Most of the firms Ecology
expects to participate in the consent order have expressed
their willingness to do so (Reale, D., 17 September 1987,
personal communication).
• A group of oil companies at the site engaged in a cooperative
effort to install a trench recovery system affecting the
subsurface region near the Globe Machine property. Product
is currently being extracted from this trench system
(Reale, D., 17 May 1988, personal communication).
12-9
-------
12.2.2 Storm Drains
Of the storm drains that discharge into the mouth of the waterway,
storm drain CI-214 is probably one of the most important sources of contamin-
ation. Storm drain CI-214 drains approximately 8 ac, and, based on seven
observations, has an estimated average discharge of 3 gal/min (Comstock, A.,
29 April 1988, personal communication). Runoff pathways to this storm
drain are not well defined. However, it is known that Coast Craft discharges
boiler blowdown to this drain. In addition, this drain receives runoff from
portions of the Unocal and Mobil Oil facilities. Elevated pH levels have
been measured in this discharge and oil sheens have been noted (Young, R.,
17 May 1988, personal communication; Comstock 1988).
Ecology collected a sediment sample from this storm drain in June 1987
(Norton, D., 15 April 1988, personal communication). Measured concentrations
of both indicator chemicals, HPAH and mercury, were greater than long-term
cleanup goals. Measured lead, zinc, and LPAH concentrations were also
greater than long-term cleanup goals.
No loading information is available for storm drain CI-214.
12.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of sources, the technologies
available for source control, and source control measures that have been
implemented to date. Second, the effects of source control and natural
recovery processes were evaluated. This evaluation was based on contaminant
concentrations and assumptions regarding the relationship between sources
and sediment contamination. Included within the evaluation was an estimate
of the degree of source control needed to correct existing sediment
contamination problems over the long term.
12.3.1 Feasibility of Source Control
The D Street petroleum storage facilities, storm drains, and to a
lesser extent, marinas are potential sources of hydrocarbons. Source
controls have been implemented or may be required for the following mechan-
isms of contaminant discharge:
• Surface runoff (storm drains)
• Groundwater seeps and infiltration
• Irregular direct spills (marinas).
Available technologies for controlling surface water runoff are
summarized in Section 3.2.2. These technologies incorporate methods of
retaining runoff onsite (e.g., berms, channels, grading, sumps), revegetating
or paving of waste materials to reduce erosion, and waste removal. Pump and
12-10
-------
treat methods, in combination with slurry walls or other diversion and
barrier techniques, are assumed feasible for control of groundwater contami-
nation. Site inspections and best management practices are feasible
controls for discharge of contaminants from marinas.
Implementation of source control measures, including best management
practices at the D Street oil facilities, is expected to result in a
significant reduction in contaminant discharges. It is estimated that
implementation of all known, available, and reasonable control technologies
will reduce contaminant loadings by up to 70 percent. This level of source
control is assumed to be feasible for both indicator chemicals (HPAH and
mercury).
12.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for HPAH and mercury. Results are reported in full in Tetra Tech
(1987a). A summary of those results is presented in this section.
The depositional environment near the mouth of City Waterway was char-
acterized by a sedimentation rate of 950 mg/cm2/yr (0.67 cm/yr) and a mixing
depth of 10 cm. The sedimentation rate was determined from 210-Pb methods
evaluated for the sediment core sample collected at Station CI-92. Two
indicator chemicals, HPAH and mercury, were used to evaluate the effect of
source control and the degree of source control required for sediment
recovery. Neither of these chemicals is expected to display losses due to
biodegradation or diffusion. Two timeframes were considered: a reasonable
timeframe (defined as 10 yr) and the long term. Results of the source
control evaluation are summarized in Table 12-2.
Effect of Complete Source Elimination--
Contaminant concentrations in surface sediments are currently near
long-term cleanup goals. If sources of contamination are not controlled,
contamination in surface sediments is expected to remain at levels near
long-term cleanup goals in the worst locations, and below long-term cleanup
goals elsewhere. If sources are completely eliminated surface sediment
concentrations throughout the area are expected to decline to less than
cleanup goals within only a few years.
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source control
is expected to reduce source input by 70 percent for HPAH and mercury. With
this, level of source control as an input value, the model predicts that
sediments with an enrichment ratio of 1.5 or lower for both HPAH and mercury
will recover within 10 yr (see Table 12-2). An enrichment ratio of
1.5 corresponds to a sediment concentration of 25,800 ug/kg for HPAH and
0.90 mg/kg for mercury. As shown in Figure 12-5, all surface sediments are
12-11
-------
TABLE 12-2. MOUTH OF THE CITY WATERWAY
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
HPAH Mercury
Station with Highest Concentration
Station identification CI-21 CI-05
Concentration3 19,180 0.60
Enrichment ratio*' 1.1 1.0
Recovery time if sources are
eliminated (yr) 2 0
Percent source control required
to achieve 10-yr recovery 23 3
Percent source control required
to achieve long-term recovery 12 2
10-Yr Recovery
Percent source control assumed
feasible 70 70
Highest concentration recovering
in 10 yra 25,800 0.90
Highest enrichment ratio of sediment
recovering in 10 yr 1.5 1.5
a Concentrations in ug/kg dry weight for organics, mg/kg dry weight for
metals.
b Enrichment ratio is the ratio of observed concentration to cleanup goal.
12-12
-------
INJ
i
CO
MOUTH OF CITY
IN10YR
Mouth of City Waterway
Indicator Chemicals
AT PRESENT
DEPTH (yd)
AREA (yd 2)
VOLUME (yd3)
IN 10 YR
DEPTH (yd)
AREA (yd 2)
VOLUME (yd3 )
1
27,000
27,000
1
0
0
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
HPAH (AET = 17,000 (ig/kg)
BIOLOGICAL EFFECTS OBSERVED
FOR NON-INDICATOR COMPOUNDS
Figure 12-5. Sediments at the mouth of City Waterway not meeting cleanup goals for indicator
chemicals at present and 10 yr after implementing feasible source control.
-------
expected to recover in 10 yr. For comparison, sediments currently exceeding
long-term cleanup goals for the indicator chemicals are also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that a 12 percent reduction in sources of HPAH is
required to maintain acceptable contaminant concentrations in freshly
deposited sediments (see Table 12-2). Only 2 percent source control is
required to achieve long-term recovery of sediments contaminated with
mercury. The actual percent reduction required in source loading is subject
to the considerable uncertainty inherent in the assumptions of the predictive
model.
As a comparison to source control requirements predicted using the
model discussed above, the reductions required to achieve cleanup goals in
storm drain sediment were calculated. On the basis of the sample collected
in June 1987 in storm drain CI-214 (Norton, D., 15 April 1988, personal
communication), sediment contaminant reductions of 55 percent would be
required for HPAH and 70 percent for mercury to achieve long-term cleanup
goals. Comparison of storm drain sediment with long-term cleanup goals
assumes no mixing of sediments with cleaner material from other sources.
Such comparisons provide a worst-case analysis of the impact of storm drain
discharge on the waterway.
12.3.3 Source Control Summary
The major apparent sources of contamination to the mouth of City
Waterway are the D Street petroleum facilities. If these sources are
completely eliminated (100 percent source control), it is predicted that
sediment concentrations of the indicator chemical HPAH in the surface mixed
layer will decline to the long-term cleanup goal of 17,000 ug/kg in only
2 yr. Surface concentrations of mercury are already at or below the long-
term cleanup goal of 0.59 mg/kg.
If sediment remedial actions are undertaken, only minimal levels of
source control will be required to maintain acceptable concentrations of the
indicator chemicals. The estimated percent reduction required for HPAH is
12 percent, and a 2 percent reduction is indicated for mercury. Additional
source control may be required to maintain sediment quality immediately
adjacent to the D Street petroleum facilities. However, very little
sediment chemistry data are currently available in this area to confirm this
statement. With 70 percent source control assumed feasible for both
indicator chemicals for the problem area as a whole, it appears possible
that acceptable sediment quality could be maintained following sediment
remedial action in the mouth of City Waterway.
12.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with HPAH concentrations
exceeding long-term cleanup goals is approximately 27,000 yd3 (see
Figure 12-5). This volume was estimated by multiplying the approximate areal
extent of sediment exceeding the cleanup goal (27,000 yd2) by the estimated
12-14 '
-------
1-yd depth of contamination. The estimated thickness of contamination is
only an approximation; only one sediment profile was collected and the
vertical resolution of the profile was poor at the depth of the contaminated
horizon.
In addition to chemical concentrations that exceed long-term cleanup
goals for indicator chemicals, biological effects were observed at one
station as where concentration of nonindicator compounds were very high (see
Figure 12-5). The volume of sediment exceeding long-term cleanup goals for
these compounds is estimated as 10,000 yd-*. With implementation of feasible
source controls, sediment concentrations in these sediments are expected to
recover to acceptable levels within 10 yr.
Ten years after implementation of feasible source controls, sediment
concentrations of indicator chemicals are expected to be at or below long-
term cleanup goals. Therefore, the volume of sediments requiring remediation
is estimated to be zero.
12.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
12.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. Although no areas of sediment contamination in the mouth of
City Waterway were identified for remediation, some areas do exceed long-
term cleanup goals. Further refinement of areas of contamination may
identify areas for remediation; therefore, an evaluation of alternatives was
performed. Areas exceeding long-term goals serve as a basis for the
evaluation. The objective of this evaluation is to identify the alternative
considered preferable to all others based on CERCLA/SARA criteria of
effectiveness, implementability, and cost.
The first step in this process is to assess of the applicability of
each alternative to remediation of contaminated sediments in the mouth of
City Waterway. Site-specific characteristics that must be considered in
such an assessment include the nature and extent of contamination; the
environmental setting; the location of potential disposal sites; and site
physical properties such as waterway usage, bathymetry, and water flow
conditions. Alternatives that are determined to be appropriate for the
waterway can then be evaluated based on the criteria presented in Chapter 4.
The indicator chemicals HPAH and mercury were selected to represent
the primary sources of contamination to the waterway (see Table 12-1).
Areal distributions for both indicators are presented in Figure 12-5. The
HPAH contamination in the mouth of City Waterway suggests that a treatment
process for organics could be an appropriate component of remedial action.
Total concentrations of metals in the waterway, which are generally less
than 2,000 mg/kg, are not expected to limit the applicability of solvent
extraction or thermal treatment. The alternatives incorporating these
treatment processes are therefore evaluated for the mouth of City Waterway.
12-15
-------
Evaluation of the no-action alternative is required by the NCP to
provide a baseline against which other remedial alternatives can be
compared. The institutional controls alternative, which is intended to
protect the public from exposure to contaminated sediments without imple-
mentation of sediment mitigation, provides a second baseline for comparison.
The three nontreatment dredging and disposal alternatives are applicable to
remediation of sediment contamination in mouth of City Waterway.
Three alternatives were eliminated from consideration for this problem
area: in situ capping, dredging with solidification and upland disposal,
and dredging with land treatment. In situ capping is eliminated because of
the need to maintain a navigation channel in the waterway. Solidification
and upland disposal is not considered because the low levels of contamination
do not warrant the additional expense over upland disposal without solidifi-
cation. Land treatment is considered to be an appropriate remedial
technology for sediments with high organic concentrations. However, land
treatment is eliminated from consideration for this problem area because the
sediments do not contain sufficient quantities of total organic carbon to
warrant the use of this technology.
It is assumed that the requirements to maintain navigational access to
the Puyallup River and Sitcum Waterway could preclude the use of a hydraulic
pipeline for nearshore disposal at the Blair Waterway disposal site.
Therefore, clamshell dredging has been chosen for evaluation in conjunction
with the nearshore disposal alternative.
The following seven sediment remedial alternatives are retained for
evaluation for the cleanup in mouth of City Waterway:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solvent extraction/upland disposal
• Clamshell dredging/incineration/upland disposal.
12.5.2 Evaluation of Alternatives
The three primary evaluation criteria are effectiveness, implement-
ability, and cost. A narrative matrix summarizing the assessment of each
alternative based on effectiveness and implementability is presented in
Table 12-3. A comparative evaluation of alternatives based on ratings of
high, moderate, and low in the various subcategories of evaluation criteria
is presented in Table 12-4. For effectiveness, the subcategories are short-
12-16
-------
EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
VENESS
ERM PROTECT!
H-
6
o
_i
(CONTAMINANT
1 MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 12-3. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE MOUTH OF CITY WATERWAY PROBLEM AREA
NO ACTION
NA
NA
Original contamination remains.
Source Inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative is ranked
seventh overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingesSon of contaminated
food species remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxicity and contam-
inant mobilty are expected to
remain at current levels or
Increase as a result of continued
source inputs. Contaminated
sediment volume Increases as
a result of continued source
Inputs.
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during Implementation.
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
Source control is Implemented
and would reduce sediment con-
tamination within a reasonable
time frame. Minor adverse im-
pacts would persist in the In-
terim.
Access restrictions and moni-
toring efforts can be implement-
ed quickly. Complete sediment
recovery is achieved naturally
and contaminant levels decline
to less than cleanup goats within
a few years. This alternative is
ranked first overall for timeli-
ness.
COM containment is not an
aspect of this alternative.
Trie potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains temporari-
ly, but at a reduced level as a
result of consumer warnings
and source controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline relatively quick-
ly as a result of sediment recov-
ery and source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity Is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Community exposure is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM In-
creases exposure potential
moderately over hydraulic
dredging. Removal with dredge
and disposal with downpipe and
diffuser minimizes handling re-
quirements. Workers wear pro-
tective gear.
Existing contaminated habitat
Is destroyed. Contaminated
sediment is resuspended during
dredging operations. Short-term
benthic habitat Impacts at the
disposal site.
Equipment and methods used j
require no development period!
Pre-implementation testing is !
not expected to be extensive. |
Waterway shipping needs delay
project completion. Tfils alter-
native is ranked third overall
for timeliness.
The long-term reliability of the
cap to prevent contaminant re-
exposure in the absence of
physical disruption is consi- ,
dered good.
(
i
i
The confinement system pre- ,
dudes public exposure to con-
taminants by isolating contami-
nated sediments from the over-
lying biota. Protection Is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment.
Thickness of overlying cap pre-
vents exposure of burrowing
organisms. Potential for con-
taminant migration is low be-
cause COM is maintained at in'
situ conditions.
The toxicity of contaminated
sediments in the confinement
zone remains at preremedlation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM to a barge offshore during
dredging and disposal. Public
access to dredge and disposal
sites is restricted. Public ex-
posure potential is low.
Clamshell dredging of COM in-
creases exposure potential
moderately over hydraulic
dredging. Workers wear pro-
tective gear.
H
Existing contaminated habitat
Is destroyed. Nearshore Inter-
tidal habitat is lost Contami-
nated sediment Is resuspended.
Dredge water can be managed
to prevent release of soluble
contaminants.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment is available and disposal
siting Issues should not delay
implementation. This alternative
is ranked second for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM.
Varying physicochemical con-
ditions in the fill may Increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment. The
potential for contaminant migra-
tion into marine environment
may increase over CAD. Physi-
cochemical changes could be
minimized by placing sediments
below the low tide elevation.
The toxicity of COM in the con-
finement zone remains at pre-
remedlation levels. Altered
conditions resulting from
dredge/disposal operations
may increase mobility of metals.
Volume of contaminated sedi-
ments is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
COM Is confined to a pipeline
during transport Public access
to dredge and disposal sites Is
restricted. Exposure from COM
spills or mishandling is possible,
but overall potential is low.
Hydraulic dredging confines
COM to a pipeline during trans-
port Dredge water contamina-
tion may Increase exposure
potential. Workers wear protec-
tive gear.
Existing contaminated habitat
is destroyed. Contaminated
sediment Is resuspended during
dredging operations. Dredge
water can be managed to pre-
vent release of soluble contami-
nants.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative Is ranked fourth
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating COM. Al-
though the potential for ground-
water contamination exists, it is
minimal. Upland disposal facil-
ities are more secure than near-
shore facilities.
Upland disposal is secure, with
negligible potential for environ-
mental impact if property de-
signed. Potential for ground-
water contamination exists.
The toxicity of COM in the con-
finement zone remains at pre-
remedlatton levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may Increase due to resuspen-
sion of sediment
CLAMSHELL DREDGE/
SOLVENT EXTRACTION
UPLAND DISPOSAL
Public access to dredge, treat-
ment and disposal sites is re-
stricted. Extended duration of
treatment operations may result
In moderate exposure potential.
Additional COM handling asso-
ciated with treating dredged
material Increases worker risk
significantly over dredge/dis-
posal options. Workers wear
protective gear.
Existing contaminated habitat
Is destroyed. Contaminated
sediment is resuspended during
dredging operations.
Bench- and pilot-scale testing
are required for the solvent ex-
traction process. Full scale
equipment Is available. This al-
ternative Is ranked fifth over-
all for timeliness.
Treated COM may be used as
inert construction material or
disposed of at a standard solid
waste landfill. Treatment ef-
fectively destroys or contains
contaminants.
Harmful organic contaminants
are removed from COM. Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal. Perma-
nent treatment for organic con-
taminants Is effected and In-
organic contaminants are Iso-
lated.
Harmful organic contaminants
are removed from COM Con-
centrated contaminants are dis-
posed of by RCRA- approved
treatment or disposal. Residual
inorganic contaminants are en-
capsulated.
Harmful contaminants are re-
moved from COM. Concen-
trated organic contaminants are
disposed of by RCRA- approved
treatment or disposal. Toxicity
and mobility considerations are
eliminated by extraction or solid-
ification.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Public access to dredge, treat-
ment and disposal sites is re-
stricted. Extended duration of
treatment operations may result
in moderate exposure potential.
Incineration of COM Is accom-
plished over an extended period
of time thereby Increasing ex-
posure risks. Additional treat-
ment process increases haz-
ards. Workers wear protec-
tive gear.
Existing contaminated habitat
Is destroyed by dredging. Sedi-
ment is resuspended during
dredging operations. Process
controls are required to reduce
potential air emissions.
Substantial COM testing and
incinerator Installation time Is
required before a thermal treat-
ment and solidification scheme
can be implemented. This alter-
native Is ranked sixth overall for
timeliness.
Treated COM may be used as
Inert construction material or
disposed of at a standard solid
waste landfill. Treatment ef-
fectively destroys or contains
contaminants.
COM containing low levels of
Inorganic contaminants may be
rendered nonhazardous. Treat-
ed COM containing residual
metals Is effectively treated by
encapsulation.
COM containing low levels of
inorganic contaminants may be
rendered nonhazardous.
COM containing low levels of
Inorganic contaminants may be
rendered nonhazardous.
12-17
-------
IMPLEMENTABILITY
TECHNICAL FEASIBILITY
L FEASIBILTY
INSTITUTIONA
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH CHEMICAL -
AND LOCATION-
SPECIFIC ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 12-3. (CONTINUED)
NO ACTION
Implementation of this alterna-
tive is feasible and reliable.
No monitoring over and above
programs established under
other authorises is implemented.
There are no O & M requirements
associated with the no action
alternative.
Approval is denied as a result of
agency commitments to mitigate
observed biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the intent of CERCLA/
SARA and NCP because of on-
going impacts.
All materials and procedures are
available.
INSTITUTIONAL
CONTROLS
Source control and institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily implemented.
Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
Some O & M is associated with
monitoring, maintenance of
warning signs, and Issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
Sediments are expected to re-
cover fully, thus meeting the In-
tent of CERCLA/SARA and the
NCP. Coordination with TPCHD
for health advisories for seafood
consumption Is required during
the recovery period.
All materials and procedures are
available to implement institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
DISPOSAL
Clamshell dredging equipment is
reliable. Placement of dredge
and capping materials, difficult,
but feasible. Inherent difficulty
In placing dredge and capping
materials at depths of 100 ft or
greater.
Confinement reduces monitoring
requirements in comparison to
institutional controls. Sediment
monitoring schemes can be
readily implemented. ,
O & M requirements are minimal.
Some O & M is associated with
monitoring (or contaminant mi-
gration and cap integrity.
Approvals from federal, state,
and local agencies are feasible.
However, disposal of untreated
COM is considered less desirable
than if COM is treated.
WISHA/OSHA worker protection
is required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Waterway CAD site
is considered available. Availa-
bility of open water CAD sites is
uncertain.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
Is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring compared with CAD.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facili-
ty siting are uncertain but are
assumed feasible. However, dis-
posal of untreated COM is con-
sidered less desirable than If
CDM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been identified
and is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Hydraulic dredging equipment
Is reliable. Secure upland con-
finement technology is well de-
veloped.
Monitoring can be readily imple-
mented to detect contaminant
migration through dikes. Im-
proved confinement enhances
monitoring over CAD. Installa-
tion of monitoring systems is
routine aspect of facility siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment.
Approvals from federal, state,
and local agencies are feasible.
Coordination is required for es-
tablishing discharge criteria for
dredge water maintenance.
However, disposal of untreated
CDM Is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy. Water quality cri-
teria apply to dredge water.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLVENT EXTRACTION/
UPLAND DISPOSAL
Sludges, soils, and sediments
have successfully been treated
using this technology. Solidifi-
cation Is effective treatment
for inorganics after organlcs
removal.
Monitoring is required only to
evaluate the reestabllshment
of benthic communities. Moni-
toring programs can be readily
Implemented.
No O & M costs are incurred at
the conclusion of CDM treat-
ment System maintenance Is
Intensive during implementation.
Approvals depend largely on re-
sults of pilot testing for extrac-
tion and solidification and the
nature of treatment residuals.
WISHA/OSHA worXer protection
required. Section 404 permit is
required. Alternative complies
with U.S. EPA's policies for on-
site disposal and permanent re-
duction in contaminant mobility.
Requires RCRA permit tor dis-
posal of concentrated organic
waste.
Process equipment available.
Disposal site availability is not a
primary concern because of re-
duction in hazardous nature of
material.
CLAMSHELL DREDGE/
INCINERATION/
UPLAND DISPOSAL
Incineration systems capable of
handling CDM have been de-
veloped, but no applications in"
volving CDM have been report-
ed. Effects of salt and moisture
content must be evaluated.
Solidification after organlcs re-
moval Is effective.
Disposal site monitoring Is not
required If treated CDM Is deter-
mined to be nonhazardous. Air
quality monitoring Is Intensive
during Implementation.
No O & M costs are Incurred at
the conclusion of CDM treat-
ment System maintenance Is
Intensive during implementation.
Approvals for Incinerator opera-
tion depend on pilot testing and
ability to meet air quality stan-
dards. Pilot testing for solidifi-
cation is required.
WISHA/OSHA worker protection
required. Section 404 permit is
required. Alternative complies
with U.S. EPA's policies for on-
site disposal and permanent re-
duction in contaminant toxicity
and mobility. Requires compli-
ance with PSAPCA standards.
Incineration equipment can be
installed onsite for CDM re-
mediation efforts. Applicable
incinerators exist. Disposal site
availability Is not a concern be-
cause of reduction in hazardous
nature of material.
12-18
-------
TABLE 12-4. EVALUATION SUMMARY FOR MOUTH OF CITY WATERWAY
r\>
i
Short-Term Protect iveness
Timeliness
Long-Terra Protectiveness
Reduction in Toxicity,
Mobility, or Volume
Technical Feasibility
Institutional Feasibility
Availability
Long-Terra Cleanup
Goal Costs*
Capital
O&M
Total
Long-Term Cleanup
Goal with 10-yr
Recovery Costs'
Capital"
o&ir.
Total b
No Action
Low
Low
Low
Low
High
Low
High
—
—
—
_„
— •
—
Institutional
Control s
Moderate
High
Moderate
Low
High
High
High
6
345
351
6
345
351
Clamshell/
CAD
High
Moderate
High
Low
Moderate
Moderate
Moderate
233
53
286
NA
NA
NA
Clamshell/
Nearshore
Di sposal
Moderate
Moderate
Moderate
Low
High
Moderate
High
682
51
733
NA
NA
NA
Hydraulic/
upland
Di sposal
High
Moderate
Moderate
Low
High
Moderate
Moderate
1.174
70
1.244
NA
NA
NA
Clamshell/
Extraction/
Upland
Di sposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
5.726
67
5.793
NA
NA
NA
Clamshell/
Incinerate/
Upl and
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
Moderate
12,992
67
13.059
NA
NA
NA
8 All costs are in $1.000.
" Implementing institutional controls will effectively eliminate the need for sediment remediation. Therefore, O&M costs were not evaluated for
the other alternatives.
-------
terni protect!veness; timeliness; long-term protectiveness; and reduction in
toxicity, mobility, or volume. For implementability, the subcategories are
technical feasibility, institutional feasibility, availability, capital
costs, and O&M costs. Remedial costs are shown only for sediments currently
exceeding long-term cleanup goal concentrations, since no sediments would
still exceed the cleanup goal concentrations 10 yr after implementing
feasible source controls (i.e., 10-yr recovery costs).
The evaluation of alternatives is similar to that presented in
Section 11.5.2 for Wheeler-Osgood Waterway, except that under institutional
controls, the problem area recovers in 2 yr, so the effectiveness criteria
and implementability receive a high ranking. In situ capping and land
treatment alternatives were not deemed appropriate and therefore not
considered for the mouth of City Waterway. The estimated volume of sediment
exceeding long-term goals in the mouth of City Waterway (27,000 yd3) is on
the same order of magnitude as that for Wheeler-Osgood Waterway (11,000 yd3).
The indicator chemicals are also similar: HPAH and mercury for mouth of
City Waterway, as compared with HPAH and zinc for Wheeler-Osgood Waterway.
The reader is referred to Section 11.5.2 for a review of the considerations
involved in the evaluation process. The evaluation summary table is
explained in detail and each low, moderate, and high rating is discussed.
12.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Institutional controls are recommended as the preferred alternative for
the mouth of City Waterway. Contaminant concentrations in the mouth of City
Waterway are less than those concentrations predicted to recover to the long-
term cleanup goals within 10 yr (in fact, the model indicates full recovery
within 2 yr). Therefore, institutional controls provide a cost-effective
and environmentally protective remedial alternative. Monitoring will
determine the effectiveness of institutional controls. If monitoring
results suggest that institutional controls are not effectively lowering
contaminant concentrations, then clamshell dredging with confined aquatic
disposal would be the currently preferred remedial alternative. Because
sediment remediation will be implemented according to a performance-based
ROD, the specific technologies identified in this latter alternative (i.e.,
clamshell dredging, confined aquatic disposal) may not be the technologies
eventually used to conduct the cleanup. New and possibly more effective
technologies available at the time remedial activities are initiated may
replace the alternative that is currently preferred. However, any new
technologies must meet or exceed the performance criteria (e.g., attainment
of specific cleanup criteria) specified in the ROD. Clamshell dredging with
confined aquatic disposal is rated high for short- and long-term protective-
ness and moderate for all other criteria except reduction in toxicity,
mobility, or volume, for which it is rated low. Implementation can be
coordinated with similar sediment remediation activities in the head of
City and Wheeler-Osgood Waterway. The confined aquatic disposal alternative
was recommended for these problem areas for the reasons provided in
Section 10.6. As indicated in Table 12-4, this alternative provides a cost-
effective means of sediment remediation, based on remediation costs for
sediments exceeding long-term goals.
12-20
-------
Although some sediment resuspension is inherent in dredging operations,
silt curtains and other available engineering controls would be expected to
minimize adverse impacts associated with redistribution of contaminated
dredged material. Potential impacts on water quality can be predicted by
using data from bench-scale tests to estimate contaminant partitioning to
the water column. Once a disposal site is selected, this alternative can be
implemented over a relatively short timeframe. Seasonal restrictions on
dredging operations to protect migrating anadromous fish are not expected to
pose a problem. Dredging activities within this problem area are consistent
with the Tacoma Shoreline Management Plan and Sections 404 and 401 of the
Clean Water Act. Close coordination with appropriate federal, state, and
local regulatory personnel will be required prior to undertaking remedial
actions.
Of the remaining alternatives, clamshell dredging with nearshore
disposal in Blair Waterway Slip 1 is feasible, as are the treatment alterna-
tives. However, nearshore disposal would be less protective than confined
aquatic disposal and would fail to take advantage of the remedial activities
that are expected to occur in the head of City Waterway (i.e., dredging with
confined aquatic disposal). The treatment options are considered too
costly, given the limited amount of additional protection they would
provide. The upland disposal alternatives would add considerable costs to
the sediment remediation effort with few additional benefits.
The no-action alternative is rated high for technical feasibility,
availability, and capital expenditures. However, the failure to mitigate
environmental and potential public impacts far outweighs these advantages.
12.7 CONCLUSIONS
The mouth of City Waterway was identified as a problem area because of
the elevated concentrations of PAH and several other organic and inorganic
chemicals. HPAH and mercury were selected as indicator chemicals to assess
source control requirements, evaluate sediment recovery, and estimate the
area and volume to be remediated. In this problem area, sediments with
concentrations currently exceeding long-term cleanup goals cover an area of
approximately 27,000 yd2, and a volume of 27,000 yd3. This volume of
material includes an estimated 10,000 yd3 of sediment in the navigation
channel which demonstrated biological effects for nonindicator compounds.
The entire area exceeding long-term cleanup goals is predicted to recover
within 10 yr following implementation of known, available, and reasonable
source control measures. The total volume of sediment requiring remediation
is therefore reduced to zero.
The primary identified sources of problem chemicals to this problem
area are the D Street petroleum storage facilities and the storm drains that
service these facilities. Source control measures required to correct these
problems and ensure the long-term success of sediment cleanup in the problem
area include capping and removal of contaminated materials, and other
methods for controlling contamination in surface runoff. Best management
practices for controlling spillage during handling of petroleum products are
also appropriate.
12-21
-------
It should be possible to control sources sufficiently to maintain
acceptable long-term sediment quality. This determination was made by
comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable. Source control requirements were developed through application
of the sediment recovery model for the indicator chemicals HPAH and mercury.
If monitoring confirms that sediment remediation is not required, then
institutional controls (implementation) are proposed as the preferred
alternative. If, however, additional refinement of the contaminated area
identifies areas of sediment remediation, clamshell dredging with confined
aquatic disposal would be the preferred remedial alternative. This
alternative will take advantage of procedures and equipment being used to
remediate sediment in the head of the waterway. The identification of these
alternatives was made following a detailed evaluation of viable alternatives
encompassing a wide range of general response actions. Because sediment
remediation will be implemented according to a performance-based ROD, the
alternative eventually implemented may differ from the currently preferred
alternative. The preferred alternatives meet the objective of providing
protection for both human health and the environment by effectively
isolating contaminated sediments at near in situ conditions in a quiescent,
subaquatic environment. Confined aquatic disposal has been demonstrated to
be effective in isolating contaminated sediments (U.S. Army Corps of
Engineers 1988). Either alternative would be consistent with the Tacoma
Shoreline Management Plan, Sections 404 and 401 of the Clean Water Act, and
other applicable environmental requirements.
The estimated cost (present worth) of implementing a monitoring program
is $351,000. This program would be used to verify that source control and
natural sediment recovery have corrected the contamination problems.
Implementation of source control measures are not included in the cost
analysis.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediments
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control
• Limited information on disposal site availability and
associated costs.
12-22
-------
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the implementation of source
controls:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures.
Implementation of institutional controls is expected to be protective
of human health and the environment and to provide a long-term solution to
the sediment contamination problems in the area. The
measures are consistent with other environmental
utilize the most protective solutions to the maximum extent practicable, and
are cost-effective.
proposed remedial
laws and regulations,
12-23
-------
13.0 RUSTON-PT. DEFIANCE SHORELINE
Potential remedial actions are defined and evaluated in this section
for the Ruston-Pt. Defiance Shoreline Waterway problem area. The problem
area is described in Section 13.1. This description includes a discussion
of the physical features of the waterway, the nature and extent of contami-
nation observed during the RI/FS field surveys, and a discussion of
anticipated or proposed dredging activities. Section 13.2 provides an
overview of contaminant sources, including site background, identification of
known and potential contaminant reservoirs, remedial activities, and current
site status. The effects of source control measures on sediment contamina-
tion levels are discussed in Section 13.3. Area and volume of sediments
requiring remediation are discussed in Section 13.4. The detailed evaluation
of the candidate sediment remedial alternatives chosen for the problem area
and indicator problem chemicals is provided in Section 13.5. The preferred
alternative is identified in Section 13.6. The rationale for its selection
is presented, and the relative merits and deficiencies of the remaining
alternatives are discussed. The discussion in Section 13.7 summarizes the
findings of the selection process and integrates required source control
with the preferred remedial alternative.
13.1 WATERWAY DESCRIPTION
The Ruston-Pt. Defiance Shoreline problem area extends along the
southwest shore of Commencement Bay from the Pt. Defiance Zoo and Aquarium
to the mouth of City Waterway. An illustration of the shoreline and the
locations of storm drain outfalls and nearby industries are presented in
Figure 13-1. The Tacoma Smelter, which began smelting lead in 1889, is also
located along the shoreline. It was modified for copper smelting in about
1906, after it was purchased by ASARCO. The southwest shoreline is fairly
steep and forested, with residential housing and small commercial establish-
ments located along the shore and on the bluff. The waterfront of the
Ruston-Pt. -Defiance Shoreline has been modified as a result of dredge and
fill operations. The peninsula enclosing the Tacoma Yacht Basin was formed
by placement of copper smelting slag, issued under permits from 1917 to
1962. Slag was also used to build up the shoreline on which much of the
ASARCO plant in now located. Between 55,000 and 90,000 yd3 of slag near the
Tacoma Yacht Basin was removed and replaced with riprap to stabilize
shoreline embankments.
The subbottom profiling that was performed as part of the Commencement
Bay Nearshore/Tideflats (N/T) RI did not extend through the problem area off
Pt. Defiance (Raven Systems and Research 1984). Sediments along the Ruston-
Pt. Defiance Shoreline are typically sands, averaging less than 20 percent
fine-grained material and having a clay content of 5 percent (Tetra Tech
1985b). A large percentage of the gravel and coarse sand found off the
ASARCO facility and slag fill areas appeared to be slag particles, based on
13-1
-------
~RS-102
RS-101
RS-004
RS-020
RS-021
RS-022
RS-028
RS-032
RS-033
1 POINT DEFIANCE FERRY TERMINAL
2 TACOMA YACHT CLUB
3 POINT DEFIANCE PARK
4 AMERICAN SMELTING &
RERNINGCO. (ASARCO)
NPDESWA 0000647
5 TACOMA NORTH SEWAGE
TREATMENT PLANT
NPDESWA0037214
6 TACOMA FIRE STATION #5 PIER
7 CONTINENTAL GRAIN CO. &
TACOMA ELEVATOR WHARF
RS-049-
RS-050
Reference: Taooma-Pierce County Health
Department (1984, 1966).
Notes: Property boundaries are approximate
based on aerial photographs and drive-
by inspections.
meters
1500
Figure13-1. Ruston-R. Defiance Shoreline - Existing industries,
businesses, and discharges.
13-2
-------
visual observations made during the development of the ASARCO interim RI
report (Parametrix et al. 1988).
13.1.1 Nature and Extent of Contamination
An examination of sediment contaminant data obtained during both RI/FS
sampling efforts (Tetra Tech 1985a, 1985b, 1986c) and historical surveys has
revealed that the problem area contains concentrations of both organic and
inorganic materials that are harmful to benthic organisms. Priority 1
contaminants that have been identified include arsenic, mercury, and LPAH.
The following Priority 2 contaminants have also been identified: cadmium,
nickel, copper, lead, zinc, antimony, HPAH, dibenzofuran, PCBs, and phthalate
esters. The following organic compounds exceeded their corresponding AET
values at only one station sampled and are therefore considered Priority 3
contaminants: biphenyl, dibenzothiophene, methylphenanthrene, methylpyrene,
4-methylphenol, 2-methylphenol, N-nitrosodiphenylamine, and an alkylated
benzene isomer. Generally, these contaminants exhibit high particle
affinity and low solubility (Tetra Tech 1987c).
Arsenic and mercury were selected as inorganic indicator chemicals for
the Ruston-Pt Defiance Shoreline problem area. Estimated area! and depth
distributions of arsenic are shown in Figure 13-2 and those for mercury are
shown in Figure 13-3. Contaminated sediments located in water depths
exceeding 200 ft were not included in the problem area because dredging
cannot occur at greater depths. The highest concentrations of arsenic and
mercury were found at sampling stations located near the main outfalls of
ASARCO (Tetra Tech 1986c). Surficial arsenic concentrations equalled or
exceeded the long-term cleanup goal of 57 mg/kg at all stations in the
problem area. Surficial mercury concentrations reached or exceeded the long-
term cleanup goal of 0.59 mg/kg at all but two sampling stations in the
problem area. Levels of contamination in the figures are normalized to
these cleanup goals. Problem sediments were defined by values of those
indicator chemicals greater than 1.0 at stations in less than 200 ft of
water. The cleanup goal for arsenic was set by the AET derived for benthic
infaunal abundance depression and the cleanup goal for mercury was set by
the oyster larvae bioassay.
Based on its presence in sediments at concentrations well above the
long-term cleanup goal, LPAH was also selected as an indicator compound for
the Ruston-Pt. Defiance Shoreline problem area. This cleanup goal was
determined by the oyster larvae bioassay. Concentrations of LPAH exceeding
the cleanup goal of 5,200 ug/kg were observed near the ASARCO docks and off
several storm drains southeast of the facility (Figure 13-4). Levels of
contamination in the figure are normalized to the long-term cleanup goal.
All sediment profiles of metals measured during the RI and FS displayed
a concentration maximum at or very near the surface. Sediment profiles of
LPAH concentrations demonstrate weak surface maxima. Remediation to a depth
of 0.5 yd was assumed based on core profiles form stations RS-91, RS-92,
RS-93, and RS-94.
13-3
-------
5.1
v
ARSENIC (mg/kg)
I I I I ! I-
0 40 80 120 ISO ' 200
RATIO TO CLEANUP GOAL
0.3V
06-
a
ui
O
0.8-
1.0-
1.2-1
* R3-91
• RS-92
— RS-93
• RS-94
Contours in ft
RS-9V
MEAN LOWER LOW WATER
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1984
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
SEDIMENT SURVEYS CONDUCTED
IN 1987
SEDIMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
Figure 13-2. Areal and depth distributions of arsenic in sediments
of Ruston-R. Defiance Shoreline, normalized to long-term
cleanup goal.
13-4
-------
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDMENT SURVEYS CONDUCTED
IN 1964
SEDMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1981)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
RS-94
Rs-93
MERCURY (mg/kg)
01 2345*78 » 10
0 2 4 6 8 10 12 14 16
RATIO TO CLEANUP GOAL
• RS-91
• RS-92
— — RS-93
RS-94
Figure 13-3. Areal and depth distributions of mercury in sediments
of Rusfon-Pt. Defiance Shoreline, normalized to long-term
cleanup goal.
13-5
-------
MEAN LOWER LOW WATER
FEASIBLITY STUDY SEDIMENT
PROFILE SURVEYS (1966)
SEDWENT SURVEYS CONDUCTED
IN 1964
SEDMENT SURVEYS CONDUCTED
BEFORE 1964 (1979-1961)
SEDMENT CONCENTRATIONS
EXCEED TARGET CLEANUP GOAL
LPAH Gig/kg)
0 |SOO 1000 1500
0 0.1 0.2 0.3
„ , RATIO TO CLEANUP GOAL
0.2-
04-
a.
IU
Q
0.8-
1.0-
--• RS-92
— RS-94
Contours in ft
0 1000
0.03
RS-92
Figure 13-4. Areal and depth distributions of LPAH in sediments
of Ruston-R. Defiance Shoreline, normalized to long-term
cleanup goal.
13-6
-------
13.1.2 Recent and Planned Dredging Pro-jert«;
The Tacoma Metropolitan Park District is currently dredging 180 yd3 of
concrete, rubble, sand, and silt from the beach adjacent to Ruston Way, south
of the ASARCO facility. Dredged material, to be disposed of on the nearby
uplands, will be replaced with 196 ydj of sand along the Ruston-Pt. Defiance
Shoreline (Heany, K., 27 October 1987, personal communication; U.S. Army
Corps of Engineers, 27 October 1987, personal communication).
Of the establishments along the shoreline, the Tacoma Yacht Bastn and
the Continental Grain Company responded when queried about future dredging
projects. Neither business plans any dredging operations in the foreseeable
future (Anonymous, 22 October 1987b, personal communication; Aylor, M.,
22 October 1987, personal communication).
13.2 POTENTIAL SOURCES OF CONTAMINATION
The ASARCO smelter began operations in the area in 1889 and continued
metal refining until 1978. Copper smelting at the site ceased in 1985 and
the arsenic trioxide plant was shut down in 1986. Other facilities currently
operating in the area include the Pt. Defiance Ferry Terminal Slip, Tacoma
Yacht Basin, City of Tacoma Fire Station No. 5 Pier, Continental Grain
Company, Tacoma Elevator Wharf, and Tacoma North Sewage Treatment Plant (see
Figure 13-1).
The Ruston-Pt. Defiance Shoreline study area was the location of the
original Tacoma settlement in the late 1800s and the site of the Tacoma
Mill, the first lumber mill on Commencement Bay, which began operation in
1869. Other industries that had been located on the Ruston-Pt. Defiance
Shoreline include eight lumber companies, two grain elevators, a lime
company, a boat building operation, a fuel company, a cold storage company,
and railroad freight warehouses.
Table 13-1 provides a summary of problem chemical and source status
information for the area. The high concentrations of metals have been
attributed largely to the three main ASARCO outfalls and the historical use
of slag as fill material and riprap. The elevated concentrations of LPAH
have been tentatively attributed to fuel oil spills, fuel combustion, and
stack emissions.
13.2.1 American Smelting and Refining Company
The ASARCO primary copper smelter is located along the Ruston-Pt. Defi-
ance Shoreline along the southwestern shore of the Commencement Bay N/T
study area. The site is owned by the American Smelting and Refining
Company, Inc., a New Jersey corporation. ASARCO, Inc. owns approximately
97 ac within the adjacent municipalities of Ruston and Tacoma. Of this,
approximately 67 ac are occupied by the smelter facility; the remainder
comprises parking areas and adjacent undeveloped property. Land use in the
vicinity of the site is primarily urban residential, with recreational and
commercial land uses nearby (Parametrix et al. 1986).
13-7
-------
TABLE 13-1. RUSTON-PT. DEFIANCE SHORELINE - SOURCE STATUS3
Chemical /Group
Mprcury
Arsenic
Cadmium
Nickel
Copper
Lead
Zinc
Antimony
1 PAH
IIPAII
I)iben7ofuran
Diphenyl
,_. Dihon/olhiophene
to Mplhylphenanlhrene
Op Molhylpyrene
1 Mrthylphenol
2 Mplhylphenol
PCRs
Phlhalate pstprs
Alkylaled hen/ene isomer
Rr-tonp
N ni irosoriiphenylamine
Chemical
Segment 2
I
1
2
2
2
2
2
2
1
2
2
3 (RS-18)
3 (RS 18)
3 (RS-18)
3 (RS 18)
3 (RS-16)
3 (RS 18)
2
2
3 (RS 16)
3 (none)
3 (RS-18)
Priority11
Segment 3
2
2
2
2
2
2
2
__
--
—
—
—
—
--
—
--
—
—
—
2
Sources
ASARCO Storm
Drains RS-003,
-004, -005
ASARCO slag
Groundwater from
ASARCO
ASARCO fuel
storage tanks,
oil , oi 1 spil Is
Fuel combustion,
emissions
Storm drains
Wood wastes
ASARCO facilities
No
c
c
c
Source ID
Yes
Potential
Potential
Potential
Potential
Potential
Potential
Potential
No
c
c
c
Source Loading
>90% of metals
load from
RS-004, RS-005
No
No
No
No
Yes
c
No
No
c
c
c
Source Status
ASARCO closed in
1986
Ongoing source
Historical source
Ongoing source
c
c
c
c
c
c
c
c
c
Sediment Profile Trends
Surface or near surface
maxima
Weak surface maxima
Variable, no significant
trend
Surface, subsurface maxima
a Source information and sediment information blocks apply to all chemicals in the
respective group, not to individual chemicals only.
b For Priority 3 chemicals, the station exceeding AET is noted in parentheses.
r- Not evaluated for this study.
-------
A lead smelting facility under the ownership of the Tacoma Smelter
Company established operations at the site in 1889. Copper production
commenced in 1902 and the smelter was purchased by the American Smelting and
Refining Company in 1905. The facility continued lead and copper smelting
operations until 1911, when lead smelting was discontinued in favor of
copper smelting. The ASARCO facility continued to operate as a primary
copper smelter until operations ceased permanently on 24 March 1985 (EPA
Docket No. 1086-04-24-106). The facility continued to operate the arsenic
production plant through January 1986 (Parametrix et al. 1986).
The ASARCO copper smelter generally operated around the clock, 7 days a
week, from approximately 1912 until the facility ceased operations in 1985.
Production averaged approximately 70,000 tons of anode copper per year.
By-products of the copper smelting process have included sulfuric acid,
liquid sulfur dioxide, arsenic trioxide, and arsenic metal (Parametrix et al.
1986). A molten slag was also created. Slag was deposited on the ground
and at the edge of Commencement Bay as fill material or sold for use as
sandblasting grit, riprap, fill material, road ballast, and ornamental rock
(Parametrix et al. 1986). In addition, the dust collected by the electro-
static precipitators and the baghouse used in the emission control operations
was used in the onsite production of marketable arsenic trioxide. Sulfur
dioxide was also generated by the converter operations onsite in sufficient
concentration and quantity to permit extraction in the onsite chemical
plants.
Emission control programs and associated operational modifications were
incorporated at the ASARCO site in 1970 (Parametrix et al. 1986). The
emissions of primary concern from the facility have been sulfur dioxide and
particulate matter containing inorganic arsenic. The principle sources of
these contaminants have been the 562-ft main stack and a variety of low-level
sources, principally the converter-reverberatory building. Closure of the
copper smelting and arsenic production facilities have reportedly reduced
emissions from approximately 59 ton/yr to fugitive dust emissions (U.S. EPA
1986d). Air quality enforcement proceedings date back to 1968, with the
adoption of Regulation I by PSAPCA governing both ambient air and emissions
standards for sulfur dioxide. Concern over arsenic emissions arose in 1972
when the Washington Department of Social and Health Services requested that
PSAPCA adopt proposed arsenic standards. A series of environmental studies
on emissions from the facility was initiated by U.S. EPA near ASARCO early
the following year (Parametrix et al. 1986). These studies indicate that
significant concentrations of heavy metals were present in local grazing
areas, surrounding soil, house dust, and fugitive emissions from site
equipment. In 1979, the Washington State Supreme Court ordered that an
environmental impact statement was required before any variance from air
emission standards could be granted to the facility. After completion of
the studies, ASARCO was granted a variance from sulfur dioxide emission
standards, but was subject to full compliance by 1987 and ordered to
continuously monitor and report ambient arsenic concentrations (Parametrix
et al. 1986).
Prior to plant shutdown, surface water had been sampled at the ASARCO
site primarily in response to accidental spills of material. Three outfalls
13-9
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at the facility have been regularly monitored as part of their NPDES permits
since 1975 (Parametrix et al. 1986). Loadings of arsenic, copper, cadmium,
lead, and zinc were generally observed to decrease from 1979 to 1984 (the
last full year of operation), with total metal loadings in 1984 estimated at
22,049 Ib. Additional sampling since closure indicates that metals loadings
to the bay have decreased by approximately 2 orders of magnitude (Norton and
Stinson 1987). Discharges are currently limited to stormwater runoff and
groundwater percolation through the site.
Parametrix et al. (1986, 1988) have compiled hydrogeologic information
regarding conditions in the vicinity of the ASARCO facility. Many of the
existing smelter facilities are located on reclaimed tideflats at the base
of the Commencement Bay sea cliffs. These tidelands were reclaimed by
placement of fill materials consisting of wood waste, debris, and smelter
slag. Groundwater formations beneath the site have been divided into three
units: the water-bearing materials within the fill beneath the site and two
additional aquifers in the underlying formations. Groundwater flow beneath
the site is primarily toward Commencement Bay (Parametrix et al. 1986,
1988). Recharge reportedly occurs via precipitation infiltration and
upgradient flow from the various aquifer formations. Tides influence the
shallow aquifer within the fill unit at the site.
During the RI (Tetra Tech 1985a) and subsequent studies (Tetra Tech
1985b, 1986c; Parametrix et al. 1988), the ASARCO site was identified as a
major source of heavy metal contaminants found along the Ruston-Pt. Defiance
Shoreline study area. Identification of the smelter site as a source of
inorganic contaminants was based on its proximity to the problem area,
measurement of identified contaminants in discharges from the site, and
documented presence of heavy metal contaminants in the production process.
Contamination of sediments with organic compounds near ASARCO is likely the
result of historical activities including spills, leakage from storage
tanks, and stack emissions (Tetra Tech 1986c). Oil was subsequently
encountered at two locations within the slag fill at ASARCO during borehole
drilling (Parametrix et al. 1988), supporting the theory that these organic
contaminants have originated from the site.
Identification of Contaminant Reservoirs Onsite--
The three major discharges associated with the ASARCO facility are the
NPDES-permitted plant outfalls to Commencement Bay (RS-003, RS-004, and
RS-005). Other historical practices that may have contributed to the
observed contamination in Commencement Bay cannot be definitely identified
because of the age of the facility and the relatively short history of
regulated emissions and discharges. Past Ecology inspections have consis-
tently failed to trace drainage lines from various buildings to their
ultimate discharge point, despite dye testing and consultations with plant
personnel (Tetra Tech 1985b).
Although there are currently no smelting or refining activities at
ASARCO, the three major outfalls continue to discharge water contaminated
with metals, presumably storm water and shallow groundwater (Tetra Tech
1986c). Recent demolition activities contributed to surface water runoff
13-10
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from scrap steel washing operations and dust suppression efforts. These
outfalls also carry runoff originating as groundwater seeps in the area of
the plant stack (Hart-Crowser & Associates 1986).
Prior to 1976, when discharge of noncontact cooling water was discon-
tinued, contact and noncontact cooling waters were mixed and discharged
through the outfalls (Tetra Tech 1985b). Typically, the south outfall
(RS-005) contained the highest metal concentrations. The flow from this
discharge was composed of saltwater noncontact cooling water from the acid
plant, springs, surface runoff from the property, and freshwater inputs from
cooling water use. The middle outfall (RS-004) drained the primary smelting
areas, the arsenic storage areas, and the copper anode pond where contact
cooling waters were recirculated. This outfall also served as a surface
stormwater runoff ditch. The north outfall (RS-003) drained the old
refinery areas and the laboratory. It has been suggested that drainage from
the arsenic kitchens was also discharged indirectly through this outfall
(Tetra Tech 1985b). During plant operations, discharge rates ranged from a
high of 3-4 MGD from RS-005 to an estimated 1 MGD from RS-003. A City of
Ruston storm drain (RS-002) north of ASARCO discharges runoff from the oil
tank storage areas and powerhouses.
The overall influence of surface soil contamination as a potential
pollutant source may have increased because of site stabilization efforts
underway at the site. Plant demolition activities are expected to greatly
increase the surface area of exposed soils at the site, resulting in a
proportionate increase in potential contaminant transport via surface water
and air.
Contaminants may also be migrating from the site via groundwater
discharge to Commencement Bay. Groundwater samples collected by Ecology in
1985 revealed arsenic, cadmium, and lead concentrations that exceeded primary
drinking water standards (Tetra Tech 1985b).
Inorganic contaminants present in groundwater beneath the ASARCO site
may have originated from slag deposited onsite during the years of active
operation. During the early years of operation, molten slag was deposited
directly into seawater. Dikes were subsequently constructed at the site and
molten slag was dumped behind them. A number of the plant's current
facilities now stand on land created by these activities. Slag depth has
been estimated to extend to 10-12 m below sea level at the seaward edge of
the property (Tetra Tech 1985b). Physical decomposition of slag by wave
action may contribute to contamination of adjacent marine sediments.
Other major routes for release of contaminants were air emissions from
the main stack and dust from process operations. In a permit granted by
PSAPCA, limitations were established for total particulates, sulfur oxides,
and arsenic emissions. The facility was also required to monitor and report
lead and mercury emissions to PSAPCA on a monthly basis (Tetra Tech 1985b).
U.S. EPA has estimated that about 34 Ib/h of arsenic may have been released
via fugitive arsenic process dust emissions, with most of the arsenic coming
from process gases in the converter operation of the plant (Tetra Tech
1985b). Chemical analysis of emissions from the main ASARCO stack during
13-11
-------
operations indicate that participate matter comprised 46 percent arsenic and
7 percent lead. The investigation also identified zinc, copper, cadmium,
chromium, and mercury in the particulate matter emanating from the stack
(Parametrix et al. 1986).
Although smelting operations are no longer being conducted on the site,
fugitive dust emissions could result from current site stabilization and
demolition activities and from resuspension of contaminated surface soils by
wind. In addition, the facility has incinerated arsenic-contaminated wood
waste generated by the demolition activities in one of the former con-
verters.
Recent and Planned Remedial Activities--
The closure of the ASARCO primary copper smelting facility in 1985 and
the shutdown of arsenic production operations in 1986 has reduced air
emissions due to process operations and greatly reduced other discharges
from the site. An Administrative Order on Consent signed by ASARCO, Inc.
and the U.S. EPA in September 1986 provided the framework for completion of
additional remedial activities (U.S. EPA 1986d).
On 10 September 1986, ASARCO and U.S EPA entered the order, in which
ASARCO agreed to undertake a series of demolition efforts to reduce potential
pollutant discharges and conduct an RI/FS at its Tacoma smelter. Phase I
sampling for the RI included collection of samples from the following
matrices: surface soil, subsurface soil, surface water, groundwater, and
marine sediment samples. Phase II will include biological sampling.
Preliminary results from groundwater, surface soil, subsurface soil, and
marine sediment samples have been presented in an interim report (Parametrix
et al. 1988). Data presented in the interim report had not been reviewed
according to all of the quality assurance/quality control (QA/QC) protocols
specified in the RI sampling and analysis plans. However, it is not
anticipated that the final QA/QC review will result in altered conclusions
from Phase I sampling (Parametrix et al. 1988).
ASARCO
Based on the results of the interim RI report, surface soils at the
nonr\CO site are a potential source of contamination for offsite migration.
Arsenic concentrations of up to 262,250 mg/kg and mercury concentrations of
up to 695 ug/kg were observed (Parametrix et al. 1988). Subsurface soil
contained arsenic and mercury concentrations of up to 2,640 mg/kg and
1.9 ug/kg, respectively (Parametrix et al. 1988). Average contaminant
concentrations for the various soil types present at the facility and for
the various particle size distributions are not presented. Measured
groundwater concentrations of arsenic, cadmium, chromium, and lead reported
on a preliminary basis by Parametrix et al. (1988) (i.e., a full quality
assurance evaluation had not been performed) were higher than maximum
contaminant levels of the Safe Drinking Water Act. Of 14 measurements
reported, the arsenic MCL of 0.05 mg/L was exceeded 10 times (highest
measured arsenic concentration = 27.5 mg/L). The cadmium MCL of 0.01 mg/L
was exceeded three times (highest measured concentration = 0.34 mg/L). The
chromium MCL, assumed to be 0.05 mg/L, was exceeded twice (highest measured
13-12
-------
/onnnntr^Jon = °'24 m9/L)' and the lead MCL of °-05 mg/L was exceeded once
(0.09 ug/L).
Results of surface water sampling and the assessment of surface soils
covering slag deposits at the ASARCO facility were incomplete, and not
included in the interim report (Parametrix et al. 1988).
The site stabilization effort was designed to remove many of the
structural components that have been in contact either directly or indirectly
with process materials. These process materials include flue dust, which
may contain inorganic arsenic. Prior to the initiation of demolition
activities, ASARCO agreed to perform the following actions:
• Remove dust from as many structures and areas as possible by
standard process methods followed by power vacuum cleaning
• Remove all asbestos-containing materials from the structures
slated for demolition
• Clean up portions of the brick flue leading to the main stack
that had collapsed during earlier maintenance operations
• Remove reusable equipment and disconnect utilities (Parametrix
et al. 1986).
Dust was suppressed during the demolition with high-pressure water-
fogging nozzles. Ambient arsenic concentrations were monitored daily at six
stations in the vicinity of the facility and one station on Vashon Island.
On several occasions, the 2.0 ug/nH ambient arsenic concentration was
exceeded at the south ore dock sampling station adjacent to Commencement
Bay. In three cases, the elevated arsenic levels were attributed to
preparation of arsenic-contaminated wood for incineration in the converter
system. Dust suppression efforts were subsequently enhanced in the wood
preparation area and no further exceedances were recorded. Arsenic levels
in excess of the criterion were also noted during the early phases of the
operation as a result of arsenic trioxide loading operations conducted by
ASARCO concurrently with the demolition (White, R., 20 July 1987, personal
communication).
The site stabilization effort resulted in removal of the two main brick
flues and pneumatic conveyor system, the plate treaters, the pipe treater,
and eight process and storage buildings. In addition, approximately
375 truckloads of scrap steel were sent for resmelting at a local metal
production facility; approximately 750 truckloads of concrete, dirt, and
brick debris were processed for disposal at a CERCLA-approved hazardous waste
disposal facility; and approximately 1,000 tons of wood were incinerated in
the site converter system following completion of acceptable emission
testing.
Visually contaminated surface soils were removed. Where possible,
soils overlying concrete foundations were also removed. Surface water
management during the demolition and site stabilization made use of the
13-13
-------
existing collection and treatment facilities. Water from the operations
flows by gravity to one of two collection points, from which it is pumped to
the No. 1 refinery building and then through a heat exchanger to a series
of lead-lined evaporation tanks. Solids are periodically removed from the
tanks by rinsing and filtration. Following evaporation with electric
heaters, the resulting wet residue is transported to ASARCO's East Helena
(Montana) plant for recovery of metals.
Surface water runoff controls implemented subsequent to the stabiliza-
tion effort include cleaning the existing drainage conduits and attempting
to revegetate the stack area and adjacent hillside by standard hydroseeding
techniques. The existing concrete pads are expected to aid in reducing
groundwater recharge and leachate generation by precipitation. The integrity
of several of the pads has been compromised, however, by the use of heavy
equipment.
At present, all phases of the initial site stabilization have been
completed in accordance with the Administrative Order on Consent. Additional
structures may be removed, and negotiations for further activities are in
progress. An amendment to the Consent Order has also been negotiated
between ASARCO and U.S. EPA to disassemble the sulfur dioxide and acid
plants on the south end of the facility and sell them to a prospective
industrial buyer (Rose, K., 19 January 1988, personal communication).
The biological studies to be conducted as a part of the Phase II RI
sampling will correlate the observed contaminant concentrations and sediment
types to area-specific variations within the biological community.
Particular attention will be paid to the effects on the biological in-
dicators of sediments containing a high percentage of weathered slag. The
ASARCO RI is currently scheduled for completion in January 1989, with
completion of the FS and submittal of the document for public review in May
1989.
13.2.2 Loading Summary
Summary loading tables are provided in Appendix E for eight inorganic
contaminants plus LPAH, HPAH, phthalates, and PCBs. Discharges along the
Ruston-Pt. Defiance Shoreline problem area for which post-RI loading data are
available include: ASARCO north outfall RS-003, ASARCO middle outfall
RS-004, and ASARCO south outfall RS-005 (ASARCO 1987; Norton and Stinson
1987). The loading tables incorporate these 1987 data.
Data for the inorganic contaminants (except mercury) are presented for
the three main ASARCO outfalls along with drains RS-022, the Tacoma North
Wastewater Treatment Plant Outfall, and RS-040 (a 48-in concrete storm drain
pipe). Mercury data and data on the organic contaminants of concern are
provided for RS-022 and RS-040.
Average loading estimates for arsenic from the three main ASARCO
outfalls for the active periods of operation at the facility range from
0.31 Ib/day (RS-003) to 400 Ib/day (RS-005). Average arsenic loadings
decreased to approximately 0.2 Ib/day at RS-005 following plant shutdown.
13-14
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Average loading rates for copper followed a similar trend, with values
?™ini9u/i /nr)(orxperiod of °Peration ranging from 1.2 Ib/day (RS-003) to
120 Ib/day (RS-005). Average copper loadings decreased to 0.14 Ib/day at
RS-005 following plant shutdown (no data were available for RS-003).
Average concentrations of antimony, cadmium, lead, and zinc in
discharges from the ASARCO middle and south outfalls (RS-004 and RS-005)
were greater than corresponding averages from the Nationwide Urban Runoff
Program study (U.S. EPA 19835), but were within 1 order of magnitude of those
values. Inorganic contaminant concentrations measured in discharges RS-022
and RS-040 were well within the range of values noted in the study (U.S. EPA
19835).
PCBs were not detected in discharges RS-022 and RS-040 during the two
sampling events recorded. Phthalate loading rates from discharge RS-022
ranged from 0.04 to 1.8 Ib/day [bis(2-ethylhexyl)phthalate and butyl benzyl
phthalate, respectively]. The phthalate compounds were not detected in
discharge RS-040. LPAH and HPAH loading rates from discharge RS-022 ranged
from 0.52 to 1.16 Ib/day.
13.3 EFFECT OF SOURCE CONTROL ON SEDIMENT REMEDIATION
A twofold evaluation of source control has been performed. First, the
degree of source control technically achievable (or feasible) through the
use of all known, available, and reasonable technologies was estimated.
This estimate is based on the current knowledge of the source of contamina-
tion, the technologies available for source control, and source control
measures that have been implemented to date. Second, the potential success
of source control was evaluated. This evaluation was based on the levels of
contamination in the sediment and assumptions regarding the relationship
between the source and sediment contamination. Included within the
evaluation was an estimate of the degree of source control needed to
maintain acceptable sediment contaminant concentrations problems over the
long term.
13.3.1 Feasibility of Source Control
The primary identified sources of contaminant discharge to the Ruston-
Pt. Defiance Shoreline problem area are runoff and groundwater inputs from
the ASARCO smelter facility. Outfall monitoring data along with the results
of the ASARCO interim RI report (Parametrix et al. 1988) indicate that
surface water runoff, surface soil, and groundwater beneath the facility are
potential ongoing sources of contamination to the adjacent sediments.
Additional data from the comprehensive surface water runoff monitoring
program conducted as part of ASARCO RI process are pending.
Available technologies for controlling quantity and quality of surface
water runoff from the ASARCO site include removal or hydraulic isolation of
contaminant sources within the drainage basin (e.g., excavation, capping),
methods for retaining runoff onsite (e.g., berms, channels, grading, sumps),
and revegetation to reduce erosion of waste materials (see Section 3.2.2).
13-15
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Treatment methods for stormwater after collection in a drainage system
also exist. Sedimentation basins and vegetation channels (or grassy swales)
have been shown to remove contamination associated with participate matter.
Removals of up to 75 percent for total suspended solids and 99 percent for
lead have been reported for detention basins (Finnemore and Lynard 1982;
Homer and Wonacott 1985). Removals of 90 percent for lead, copper, and zinc
and 80 percent for total suspended solids have been achieved using grassy
swales (Horner and Wonacott 1985; Miller 1987).
Recent efforts on the part of ASARCO to revegetate the areas of the
site exposed by the site stabilization effort have met with limited success,
possibly because of extremely dry conditions that prevailed during the
incubation period following the hydroseeding effort. Continued revegetation
efforts under more favorable conditions may be warranted to stabilize
surface soils prior to initiating remedial actions.
Pump and treat methods are feasible for control of groundwater contami-
nation. Several existing acceptable treatment technologies are available
for the identified inorganic groundwater contaminants. However, placement
of subsurface barriers to enhance groundwater isolation or diversion to
minimize fluxes to the adjacent sediments would be complicated by the
presence of slag throughout the area adjacent to the bay.
Given the contaminant types, confidence in the identification of the
source of contamination, and available control technologies, it is estimated
that implementation of all known, available, and reasonable technologies
will reduce contaminant inputs to the problem area by 95 percent.
Conclusion--
For the problem area, the estimated maximum level of source control for
the three indicator chemicals is 95 percent. This estimate is based on
cessation of ASARCO operations and ongoing site stabilization efforts. The
RI/FS process currently underway at the facility should adequately define
contaminant sources, migration pathways, and mitigation technologies. LPAH
contamination tentatively attributed to past fuel spills during off-loading
and storage should be eliminated as a result of closure operations. More
precise source control estimates require source-specific information
regarding arsenic and mercury inputs, which is beyond the scope of this
document.
13.3.2 Evaluation of the Potential Success of Source Control
The relationship between source loading and sediment concentration of
problem chemicals was evaluated by using a mathematical model. (Details of
the model are presented in Appendix A.) The physical and chemical processes
of sedimentation, mixing, and decay were quantified and the model was
applied for the indicator chemicals arsenic, mercury, and LPAH. Results are
reported in full in Tetra Tech (1987a). A summary of those results is
presented in this section.
13-16
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The depositional environment along the Ruston-Pt. Defiance Shoreline
was poorly characterized because of unacceptable excess 210-Pb data, lack of
available dredging records, and lack of sediment core discontinuities.
Sediment accumulation rates in this area are probably highly variable based
on the observed grain size distribution. Accumulation rates appear to
decrease along the shoreline toward Pt. Defiance because of strong longshore
currents. This decrease is reflected in the presence of increasingly coarse
sediments toward Pt. Defiance (Tetra Tech 1987a; Parametrix et al. 1988).
The presence of silt in the surface sediments at Stations RS-91, RS-92, and
RS-94, which are located along the shoreline adjacent to the ASARCO facility,
suggest that particle deposition is enhanced by shoreline structures. It
can be assumed that the deposition of naturally derived particulate material
is quite low in the problem area. A sedimentation rate of <200 mg/cm^/yr
(<0.12 cm/yr) and a mixing depth of 10 cm were selected as representative of
this problem area. Three indicator chemicals (LPAH, arsenic, and mercury)
were used to evaluate the effect of source control and the degree of source
control required for sediment recovery. Losses due to biodegradation and
diffusion were determined to be negligible for these chemicals. Two
timeframes were considered: a reasonable timeframe (defined as 10 yr) and
the long term. All three indicator chemicals along the Ruston-Pt. Defiance
Shoreline were assumed to be in steady-state with sediment accumulation.
This assumption is environmentally protective in that the recent shutdown of
the ASARCO plant would be expected to result in a decrease in contaminant
loading. However, termination of activities in 1986 would not be expected
to be reflected in metal profiles collected the same year. Results of the
sediment recovery evaluation are summarized in Table 13-2.
Effect of Complete Source Elimination--
If sources are completely eliminated, recovery times are predicted to
be 379 yr for arsenic, 377 yr for mercury, and 112 yr for LPAH. Recovery in
the 10-yr timeframe will thus require sediment remedial action.
Effect of Implementing Feasible Source Control--
Implementation of all known, available, and reasonable source controls
is expected to reduce source inputs by 95 percent for the indicator
contaminants arsenic, mercury, and LPAH. With this level of source control
as an input value, the model predicts that sediments with an enrichment
ratio of 1.1 (i.e., arsenic concentrations of 63 mg/kg dry weight, mercury
concentrations of 0.66 mg/kg dry weight, and LPAH concentrations of
5,800 ug/kg dry weight) will recover to the long-term cleanup goal within
10 yr (see Table 13-2). The surface area of sediments not recovering to the
cleanup goal within 10 yr is shown in Figure 13-5. For comparison, sediments
currently exceeding long-term cleanup goals for the indicator chemicals are
also shown.
Source Control Required to Maintain Acceptable Sediment Quality--
The model predicts that 99 percent of the arsenic, 97 percent of the
mercury, and 52 percent of the LPAH inputs must be eliminated to maintain
acceptable contaminant concentrations in freshly deposited sediments (see
13-17
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TABLE 13-2. RUSTON - PT. DEFIANCE SHORELINE
SUMMARY OF SEDIMENT RECOVERY CALCULATIONS
Indicator Chemicals
Arsenic Mercury LPAH
Station with Hiahest Concentration
Station identification
Concentration3
Enrichment ratiob
Recovery time if sources are
eliminated (yr)
Percent source control required
to achieve 10-yr recovery
Percent source control required
to achieve long-term recovery
Averaae of Three Hiahest Stations
Concentration3
Enrichment ratiob
Percent source control required
to achieve long-term recovery
10-Yr Recovery
Percent source control assumed
feasible
Highest concentration recovering
in 10 yr3
Highest enrichment ratio of sediment
recovering in 10 yr
RS-17
12,200
214
379
NPc
99
10,300
181
99
95
63
1.1
RS-18
52
88
377
NPc
98
32.7
33
97
95
0.66
1.1
RS-18
20,190
3.9
112
NPC
74
10,900
2.1
52
95
5,800
1.1
a Concentrations in ug/kg dry weight for organics, mg/kg dry weight for
metals.
b Enrichment ratio is the ratio of observed concentration to cleanup goal.
c NP = Not possible.
13-18
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Ruston-Pt. Defiance
Indicator Chemicals
Contours in ft
AT PRESENT
DEPTH (yd)
AREA(yd2)
VOLUME (yd3 )
IN10YR
DEPTH (yd)
AREA(yd2)
\ VOLUME (yd3)
i i
0.5
1,176,000
588,000
0.5
1,150,000
575,000
FEASIBILITY STUDY SEDIMENT
PROFILE SURVEYS (1986)
SEDIMENT SURVEYS CONDUCTED
IN 1084
SEDIMENT SURVEYS CONDUCTED
BEFORE 1984 (1979-1981)
SEDIMENT SURVEYS CONDUCTED
IN 1987
LPAH (AET = 5,200 ng/kg)
MERCURY (AET = 0.59 mg/kg)
ARSENIC (AET = 57 mg/kg)
Figure 13-5. Sediments along the Ruston-Pt. Defiance Shoreline not meeting cleanup goals for
indicator chemicals at present and 10 yr after implementing feasible source control.
-------
Table 13-2). These estimates are based on the average of the three highest
enrichment ratios measured for the indictor chemicals in the problem area.
These values are presented for comparative purposes; the actual percent
reduction in source loading is subject to the uncertainty inherent in the
assumptions of the predictive model. These ranges probably represent upper
limit estimates of source control requirements since the assumptions
incorporated into the model are considered to be environmentally protective.
13.3.3 Source Control Summary
The major identified source of arsenic and mercury to the Ruston-
Pt. Defiance Shoreline is the ASARCO facility. The source of LPAH is not
clearly defined and may be historic. If the sources of these indicator
chemicals are completely eliminated, it is predicted that sediment concen-
trations in the surface mixed layer will not recover to long-term cleanup
goals for over 100 yr for LPAH (long-term cleanup goal of 5,200 ug/kg).
Recovery and would require approximately 380 yr each for arsenic and mercury
(long-term cleanup goals of 57 mg/kg and 0.59 mg/kg, respectively). Sediment
remedial action will therefore be required to mitigate the observed and
potential adverse biological effects associated with sediment contamination
within a reasonable timeframe.
Substantial levels of source control will also be required to maintain
acceptable sediment concentrations of arsenic and mercury, even with sediment
cleanup. The estimated percent reduction required for long-term maintenance
is 99 percent for arsenic and 97 percent for mercury, based on the three
highest observed concentrations for these two indicator chemicals. The
estimated percent reduction required for long-term sediment maintenance for
the indictor chemical LPAH is considerably lower at 52 percent. Based on
September 1987 NPDES permit monitoring data collected by ASARCO, arsenic
loading rates have been reduced by approximately 99 percent since the
facility shut down. Average loading rates for the south outfall (RS-055)
from November 1975 to September 1982 were 400 Ib/day arsenic (range
7.4-2,300), while average loadings in September 1987 were 0.22 Ib/day (range
0.02-0.89). A similar reduction was noted for RS-004, the ASARCO middle
outfall, with loadings over the same time period dropping from 78 Ib/day to
0.79 Ib/day.
With 95 percent source control assumed to be feasible (i.e., known,
available, and reasonable) for the three indicator chemicals in the Ruston-
Pt. Defiance problem area, it appears that acceptable sediment quality can
be readily maintained for LPAH. The level of source control required to
maintain adequate sediment quality is very high for arsenic and mercury
because enrichment ratios are great for those compounds, especially in the
vicinity of the ASARCO outfalls. The assumed feasible level of source
control (95 percent), the highest for this FS, reflects remaining uncertain-
ties in identifying that all contaminant sources and uncertainties regarding
implementation and effectiveness of mitigative actions. Thorough site
characterization of the ASARCO facility to identify all contaminant sources
and migration pathways along with selection and proper implementation of
effective site remedial measures may, in fact, provide the necessary level
13-20
-------
adequate sed^ent quality following sediment
13.4 AREAS AND VOLUMES OF SEDIMENT REQUIRING REMEDIATION
The total estimated volume of sediment with arsenic, mercury, and LPAH
concentrations exceeding long-term cleanup goals is approximately 588,000 yd-*
(see Figure 13-5). This volume was estimated by multiplying the areal
extent of sediment exceeding the cleanup goal (1,176,000 yd^\ by the
estimated 0.5-yd depth of contamination (see contaminant sediment profiles
in Figures 13-2, 13-3, and 13-4). Estimates of the areal extent of
sediments exceeding long-term cleanup goals are subject to considerable
uncertainty because the seaward extent of sampling stations during the RI/FS
sampling was extremely limited. Outer limits of contamination were linearly
interpolated from enrichment ratios for existing sampling stations.
However, the contaminated areas presented agree well with the preliminary
findings of the ASARCO RI for marine sediment surface sampling. In the
interim RI report, Parametrix et al. (1988) reviewed data from over
100 surface sediment sampling stations. Their estimated surface area of
arsenic concentrations exceeding the long-term cleanup goal was slightly
greater and included an area northwest of the ASARCO facility (seaward from
the peninsula formed northeast of the yacht basin) where the outer (seaward)
limit of contamination could not be defined. The bottom off the Ruston-
Pt. Defiance Shoreline in this area is very steep and even samples at depths
greater than 200 ft were contaminated above the target cleanup goal area.
These stations are not, however, included in the problem area because
sediments deeper than 200 ft cannot be dredged. This area was also
characterized as containing a relatively high percentage of slag particles.
For volume calculations, depths were slightly overestimated. This
conservative approach was taken to reflect the fact that depth to the
contaminated horizon cannot be accurately dredged, to account for dredge
technique tolerances, and to account for uncertainties in sediment quality
at locations between sediment profile sampling stations.
The total estimated volume of sediments with arsenic, mercury, or LPAH
concentrations that are still expected to exceed long-term cleanup goals
10 yr .following implementation of feasible levels of source control is
575,000 yd3. This volume was estimated by multiplying the areal extent of
sediment contamination with enrichment ratios greater than 1.1 (see
Table 13-2), an area of 1,150,000 yd2, by the estimated 0.5-yd depth of
contamination. This volume includes sediments containing a high percentage
of slag particles. In the event that the biological evaluation conducted as
part of the facility's RI effort demonstrates that this material is
biologically inert, further sediment volume refinement may be warranted.
This volume is also an approximation, accounting for uncertainties in
sediment profile resolution and dredging tolerances. For the Ruston-
Pt. Defiance Shoreline problem area, this is the volume of sediment requiring
remediation.
13-21
-------
13.5 DETAILED EVALUATION OF SEDIMENT REMEDIAL ALTERNATIVES
13.5.1 Assembly of Alternatives for Analysis
The 10 sediment remedial alternatives identified in Chapter 3 broadly
encompass the general approaches and technology types available for sediment
remediation. In the following discussion, each alternative is evaluated to
determine its suitability for the remediation of contaminated sediments in
the Ruston-Pt. Defiance Shoreline problem area. The objective of this
evaluation is to identify the alternative considered preferable to all
others based on CERCLA/SARA criteria of effectiveness, implementability, and
cost.
The first step in this process is to assess the applicability of each
alternative in the problem area. Site-specific characteristics that must be
considered in such an assessment include the nature and extent of contamina-
tion; the environmental setting; and site physical properties, including
shoreline usage, bathymetry, and water flow conditions. Alternatives that
are determined to be appropriate for the waterway can then be evaluated based
on the criteria discussed in Chapter 4.
The indicator chemicals arsenic, mercury, and LPAH were selected to
represent the primary source of contamination to the problem area: the
ASARCO smelter. Areal distributions for all three indicators are presented
in Figure 13-5 to indicate the degree to which contaminant groups overlap
based on long-term cleanup goals and estimated 10-yr sediment recovery.
Sediment remedial alternatives selected for the Ruston-Pt. Defiance
Shoreline have been selected based on the prevalence of inorganic contamina-
tion. Alternatives developed specifically to treat organic contaminants
(i.e., solvent extraction, incineration, and land treatment) have been
eliminated from consideration based on limited potential effectiveness. The
solidification treatment alternative is a proven technology for the
encapsulation and immobilization of inorganic contaminants and is retained
for detailed evaluation.
Of the nontreatment alternatives, in situ capping has been eliminated
from further consideration based on the steep bathymetric gradients present
in the problem area. Gradients range from approximately 5 percent in the
nearshore areas off the ASARCO facility to up to 30 percent off the slag
fill area seaward of the yacht basin. The effectiveness of in situ capping
could also be compromised by the uncertainty regarding the depositional
environment of the Ruston-Pt. Defiance Shoreline area (see Section 13.3.2),
and the depth of contamination observed (documented to depths of over
200 ft).
The nature of the contamination in the problem area also requires
modification of the disposal options for the nontreatment dredging alterna-
tives. Data obtained during both the Commencement Bay N/T RI/FS effort and
the ASARCO RI indicate that extremely high levels of inorganic contamination
are present off the ASARCO facility in the vicinity of the three main
outfalls and off the slag fill area adjacent to the yacht basin (Tetra Tech
13-22
-------
1985a; Parametrix et al. 1988). Commencement Bay N/T RI data revealed
arsenic concentrations of up to 12,000 rag/kg (enrichment ratio of approxi-
mately 210) with several values over 8,500 mg/kg (enrichment ratio of
approximately 150). The ASARCO interim RI report revealed a significant
surface area near the facility and seaward of the yacht basin slag fill area
for an undefined distance with arsenic values exceeding 3,000 mg/kg
(enrichment ratios exceeding 50).
Based on dredged material leachate studies conducted as part of the
Puget Sound Region Homeporting Project, U.S. Army Corps of Engineers (1986c)
concluded that mobility of metals and organic contaminants is low under
anaerobic conditions, teachability of arsenic, however, was greater under
anaerobic conditions than under aerobic conditions. Approximately 7 percent
of the total sediment arsenic leached in sequential aerobic leaching tests.
Although the presence of weathered slag in the sediments off the Ruston-
Pt. Defiance Shoreline may reduce the percent arsenic available for leaching,
based on past investigations (Crecelius 1986) an added measure of protec-
tiveness is warranted at the highest observed concentrations.
Because of the high arsenic concentrations, the increased potential for
water column impacts during dredged material placement, and the increased
potential for migration of arsenic from a subaquatic (anaerobic) disposal
site, the confined aquatic disposal option has been modified to include
upland disposal for sediments containing greater than 3,000 mg/kg arsenic.
Based on data in the ASARCO interim RI report (Parametrix et al. 1988),
20 percent of the total volume identified as requiring remediation
(575,000 yd3) is assumed to require upland disposal. It has further been
assumed that an upland disposal facility for this material could be sited and
developed within the ASARCO property to facilitate implementation of this
alternative. The disposal facility may be developed in conjunction with
other remedial actions for the ASARCO site.
The alternatives involving dredging with nearshore and upland disposal
are also retained for further evaluation. Although some modifications to
the dredging techniques may be required due to bathymetric and depth
considerations (e.g., pneuma pump system for hydraulic dredging), these
options are technically feasible for the problem area.
It is assumed that the requirements to maintain navigational access to
the Puyallup River and Sitcum Waterway could preclude the use of a hydraulic
pipeline for nearshore disposal at the Blair Waterway disposal site.
Therefore, clamshell dredging has been chosen for evaluation in conjunction
with the nearshore disposal alternative.
Evaluation of the no-action alternative is required by the NCP to
provide a baseline against which other remedial alternatives can be
compared. The institutional controls alternative, intended to protect the
public from direct or indirect exposure to contaminated sediments without
implementing sediment mitigation, provides a second baseline for comparison.
13-23
-------
The following six sediment remedial alternatives are evaluated for the
cleanup of the Ruston-Pt. Defiance Shoreline problem area:
• No action
• Institutional controls
• Clamshell dredging/confined aquatic and upland disposal
• Clamshell dredging/nearshore disposal
• Hydraulic dredging/upland disposal
• Clamshell dredging/solidification/upland disposal.
13.5.2 Evaluation of Alternatives
The three primary evaluation criteria are effectiveness, implement-
ability, and cost. A narrative matrix summarizing the assessment of each
alternative based on effectiveness and implementability is presented in
Table 13-3. The alternatives for the confined aquatic and upland disposal
options are evaluated separately in the narrative matrix. A comparative
evaluation of alternatives based on ratings of high, moderate, and low in
the various subcategories of evaluation criteria is presented in Table 13-4.
For effectiveness, the subcategories are short-term protectiveness; timeli-
ness; long-term protectiveness; and reduction in toxicity, mobility, or
volume. For implementability, the subcategories are technical feasibility,
institutional feasibility, availability, capital costs, and O&M costs.
Remedial costs are shown for sediments currently exceeding long-term cleanup
goal concentrations and also for sediments that would still exceed the
cleanup goal concentrations 10 yr after implementing feasible source
controls (ie., 10-yr recovery costs).
Short-Term Protectiveness--
The comparative evaluation for short-term protectiveness resulted in
low ratings for no-action and institutional controls because the adverse
biological and potential public health impacts continue with the contaminated
sediments remaining in place. Source control measures initiated to date and
additional measures initiated as part of the institutional controls would
tend to reduce sediment contamination with time, but adverse impacts would
persist for an extensive period during sediment recovery.
The alternative requiring clamshell dredging/nearshore disposal is
rated moderate under this criterion because nearshore habitat would be lost
in siting the disposal facility and because direct worker exposure would be
expected during dredging operations. The clamshell dredging/confined
aquatic/upland disposal alternative is rated moderate under this criterion.
Although placement of the highly contaminated sediments in an upland disposal
facility should help minimize water column impacts associated with subaquatic
disposal, water column impacts may occur as a result of sediment removal.
The confined aquatic/upland disposal alternative also involves the potential
13-24
-------
EFFECTIVENESS
SHORT-TERM PROTECTIVENESS
TIMELINESS
VENESS
ERM PROTECT!
K
6
0
[CONTAMINANT
MIGRATION
COMMUNITY
PROTECTION
DURING
IMPLEMENTA-
TION
WORKER
PROTECTION
DURING
IMPLEMENTA-
TION
ENVIRONMENTAL
PROTECTION
DURING
IMPLEMENTA-
TION
TIMELINESS
LONG-TERM
RELIABILITY OF
CONTAINMENT
FACILITY
PROTECTION OF
PUBLIC HEALTH
PROTECTION OF
ENVIRONMENT
REDUCTION IN
TOXICITY,
MOBILITY, AND
VOLUME
TABLE 13-3. REMEDIAL ALTERNATIVES EVALUATION MATRIX FOR THE RUSTON - PT. DEFIANCE SHORELINE PROBLEM AREA
NO ACTION
NA
NA
Original contamination remains.
Source inputs continue. Ad-
verse biological Impacts con-
tinue.
Sediments are unlikely to recov-
er in the absence of source con-
trol. This alternative is ranked
sixth overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains.
Original contamination remains.
Source inputs continue.
Exposure potential remains at
existing levels or increases.
Sediment toxicity and contam-
inant mobilty are expected to
remain at current levels or
increase as a result of continued
source Inputs. Contaminated
sediment volume Increases as
a result of continued source
Inputs.
INSTITUTIONAL
CONTROLS
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during implementation.
There are no elements of insti-
tutional control measures that
have the potential to cause
harm during Implementation.
Source control Is implemented
and would reduce sediment con-
tamination with time, but adverse
impacts would persist in the in-
terim.
Access restrictions and moni-
toring efforts can be implement-
ed quickly. Partial sediment re-
covery is achieved naturally,
but significant contaminant
levels persist. This alternative is
ranked fifth overall for timeliness.
COM containment is not an
aspect of this alternative.
The potential for exposure to
harmful sediment contaminants
via ingestion of contaminated
food species remains, albeit at
a reduced level as a result of
consumer warnings and source
controls.
Original contamination remains.
Source inputs are controlled.
Adverse biological effects con-
tinue but decline slowly as a
result of sediment recovery and
source control.
Sediment toxicity is expected
to decline slowly with time as a
result of source input reductions
and sediment recovery. Con-
taminant moblity Is unaffected.
CLAMSHELL DREDGE/
CONFINED AQUATIC
AND UPLAND DISPOSAL
Community exposure is negli-
gible. COM is retained offshore
during dredge and disposal
operations. Public access to
area undergoing remediation is
restricted.
Clamshell dredging of COM in-
creases exposure potential mod-
erately over hydraulic dredging.
Removal with dredge and dispos-
al with downpipe and diffuser min-
, Imizes handling requirements.
COM handling during transport to
upland site Increases worker risk
Workers wear protective gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment Is re-
suspended during dredging op-
erations. Benthic habitat Is im-
pacted at the disposal site.
Disposal siting and facility con-
struction may delay project im-
plementation. This alternative
is ranked third overall for timeli-
ness instead of second due to
upland disposal requirements.
The long-term reliability of cap to
prevent contaminant reexposure
in a quiescent, sub-aquatic ertvir
onment Is considered good. Up-
land confinement facilities were
considered structurally reliable.
Dike and cap repairs can be read
ily accomplished. Underdrain
and liner cannot be repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating contami-
nated sediments from the public
and the biota adjacent to the
CAD site. Protection is ade-
quate.
The confinement system pre-
cludes environmental exposure
to contaminated sediment Po-
tential for contaminant migration
is reduced by maintaining COM
at in situ conditions at CAD site.
Potential for groundwater con-
tamination exists at upland site.
The toxicity of contaminated
sediments in the confinement
zone remains at preremediation
levels.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging confines
COM to a barge offshore during
transport Public access to
dredge and disposal sites is re-
stricted. Public exposure po-
tential Is tow.
Clamshell dredging of COM in-
creases exposure potential mod-
erately over hydraulic dredging.
Workers wear protective gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Nearshore intertidal habitat
Is lost Contaminated sediment
Is resuspended.
Dredge and disposal operations
could be accomplished quickly.
Pre-implementation testing and
modeling may be necessary, but
minimal time is required. Equip-
ment is available. Disposal sit-
ing issues should not delay im-
plementation. This alternative is
ranked first for timeliness.
Nearshore confinement facilities
are structurally reliable. Dike
and cap repairs can be readily
accomplished.
The confinement system pre-
cludes public exposure to con-
taminants by isolating CDM.
Varying physicochemical con-
ditions in the fill may increase
potential for contaminant migra-
tion over CAD.
The confinement system pre-
cludes environmental exposure
to contaminated sediment. The
potential for contaminant migra-
tion into marine environment
may increase over CAD. Adja-
cent fish mitigation site is sen-
sitive area.
The toxicity of CDM in the con-
finement zone remains at pre-
remediation levels. Altered
conditions resulting from
dredge/disposal operations
may Increase mobility of metals.
Volume of contaminated sedi-
ments Is not reduced.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
CDM is confined to a pipeline
during transport. Public access
to dredge and disposal sites Is
restricted. Exposure from CDM
spills or mishandling is possible,
but overall potential Is low.
Hydraulic dredging confines
CDM .to a pipeline during trans-
port Dredge water contamina-
tion may increase exposure po-
tential. Workers wear protective
gear.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment is
resuspended during dredging
operations. Dredge water can
be managed to prevent release
of soluble contaminants.
Equipment and methods used
require no development period.
Pre-implementation testing is
not expected to be extensive.
This alternative is ranked second
overall for timeliness.
Upland confinement facilities
are considered structurally
reliable. Dike and cap repairs
can be readily accomplished.
Underdrain or liner cannot be
repaired.
The confinement system pre-
cludes public exposure to con-
taminants by isolating CDM. Al-
though the potential for ground-
water contamination exists, It is
minimal. Upland disposal facili-
ties are more secure than near-
shore facilities.
Upland disposal is secure, with
negligible potential for environ-
mental impact if properly de-
signed. Potential for ground-
water contamination exists.
The toxicity of CDM in the con-
finement zone remains at pre-
remediation levels. The poten-
tial for migration of metals is
greater for upland disposal than
for CAD or nearshore disposal.
Contaminated sediment volumes
may Increase due to resuspen-
ston of sediment
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Public access to dredge treat-
ment and disposal sites Is re-
stricted. Exposure from CDM
spills or mishandling Is possible,
but overall potential is low.
Additional CDM handling asso-
ciated with treatment Increases
worker risk over dredge/disposal
options. Workers wear protec-
tive gear. Increased potential
for worker exposure due to di-
rect handling of CDM.
Existing contaminated habitat
Is destroyed but recovers rapid-
ly. Contaminated sediment Is
resuspended during dredging
operations.
Substantial CDM testing and
equipment development are
reouired before a solidification
scheme can be Implemented.
This alternative Is ranked fourth
overall for timeliness.
Long-term reliability of solidifica-
tion treatment processes for
CDM are believed to be ade-
quate. However, data from
which to confirm long-term relia-
bility are limited. Upland dispos-
al facilities are structurally reli-
able.
Solidification is a more protec-
tive solution than dredge/dis-
posal alternatives. The poten-
tial for public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Solidification Is a more protec-
tive solution than dredge/dis-
posal alternatives. The poten-
tial for public exposure is signi-
ficantly reduced as a result of
contaminant immobilization.
Contaminants are physically
contained, thereby reducing
toxicity and the potential for
contaminant migration com-
pared with non-treatment alter-
natives. Metals and organics
are encapsulated.
13-25
-------
IMPLEMENTABILITY
TECHNICAL FEASIBILITY
L FEASIBILTY
INSTITUTIONA
AVAILABILITY
FEASIBILITY AND
RELIABILITY OF
REMEDIAL
ACTION
PROCESS
OPTIONS
IMPLEMENTATION
OF MONITORING
PROGRAMS
IMPLEMENTATION
OF OPERATING
AND MAINTE-
NANCE
PROGRAMS
APPROVAL OF
RELEVANT
AGENCIES
COMPLIANCE
WITH ARARS
AND GUIDELINES
AVAILABILITY OF
SITES, EQUIP-
MENT, AND
METHODS
TABLE 13-3. (CONTINUED)
NO ACTION
Implementation of this alterna-
tive is feasible and reliable.
No monitoring over and above
programs established under
other authorities Is implemented.
There are no O & M requirements
associated with the no action
alternative.
This alternative Is expected to
be unacceptable to resource
agencies as a result of agency
commitments to mitigate ob-
served biological effects.
AET levels in sediments are ex-
ceeded. No permit requirements
exist. This alternative fails to
meet the Intent of CERCLA/
SARA and NCP because of on-
going Impacts.
All materials and procedures are
available.
INSTITUTIONAL
CONTROLS
Source control and Institutional
control measures are feasible
and reliable. Source control
reliability assumes all sources
can be Identified.
Sediment monitoring schemes
can be readily Implemented.
Adequate coverage of problem
area would require an extensive
program.
O & M requirements are minimal.
Some O & M Is associated with
monitoring, maintenance of
warning signs, and Issuance of
ongoing health advisories.
Requirements for agency appro-
vals are minimal and are ex-
pected to be readily obtainable.
AET levels in sediments are ex-
ceeded. This alternative fails to
meet intent of CERCLA/SARA
and NCP because of ongoing
impacts. State requirements
for source control are achieved.
Coordination with TPCHD for
health advisories for seafood
consumption is required.
All materials and procedures are
available to implement institu-
tional controls.
CLAMSHELL DREDGE/
CONFINED AQUATIC
AND UPLAND DISPOSAL
Clamshell dredging equipment
Is reliable. Placement of dredge
and capping materials difficult,
but feasible. Inherent-difficulty
In placing dredge and capping
materials at depths of 1 00 ft or
greater. Secure upland confine-
ment technology Is wen develop-
ed.
Confinement reduces monitoring
requirements In comparison to
institutional controls. Sediment
monitoring schemes can be
readily Implemented.
O & M requirements consist of
Inspections, groundskeeping,
and maintenance of monitoring
equipment at the upland facility.
Some O & M Is associated with
monitoring for contaminant mi-
gration and cap integrity at the
CAD site.
Approvals from federal, state,
and local agencies are feasible.
Approvals for facility siting are
uncertain but assumed feasible.
(However, disposal of untreated
COM is considered less desir-
able than If COM Is treated.
WISHA/OSHA worker protection
Is required.' Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed.
Equipment and methods to im-
plement alternative are readily
available. Availability of open
water CAD sites Is uncertain.
Potential upland disposal sites
have been Identified but none
are currently available.
CLAMSHELL DREDGE/
NEARSHORE DISPOSAL
Clamshell dredging equipment
is reliable. Nearshore confine-
ment of COM has been success-
fully accomplished.
Monitoring' can be readily Imple-
mented to detect contaminant
migration through dikes. Instal-
lation of monitoring systems Is
routine aspect of facility siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state,
and local agencies are feasible.
Availability of approvals for facil-
ity siting are assumed feasible.
However, disposal of untreated
COM is considered less desir-
able than if COM Is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA and shoreline manage-
ment programs must be address-
ed. Alternative complies with
U.S. EPA's onsite disposal
policy.
Equipment and methods to im-
plement alternative are readily
available. A potential nearshore
disposal site has been identified
and is currently available.
HYDRAULIC DREDGE/
UPLAND DISPOSAL
Clamshell dredging equipment
Is reliable. Secure upland con-
finement technology is well de-
veloped.
Monitoring can be readily Imple-
mented to detect contaminant
migration through dikes and
liners. Improved confinement
enhances monitoring over CAD.
Installation of monitoring sys-
tems Is routine aspect of facility
siting.
O & M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment
Approvals from federal, state.
and local agencies are feasible.
However, disposal of untreated
COM Is considered less desir-
able than if COM is treated.
WISHA/OSHA worker protection
required. Substantive aspects
of CWA, hydraulics, and shore-
line management programs must
be addressed. Alternative com-
plies with U.S. EPA's onsite dis-
posal policy.
Equipment and methods to im-
plement alternative are readily
available. Potential upland dis-
posal sites have been identified
but none are currently available.
CLAMSHELL DREDGE/
SOLIDIFICATION/
UPLAND DISPOSAL
Solidification technologies for
treating COM on a large scale
are conceptual. Implementation
is considered feasible, but reli-
ability is unknown. Bench-scale
testing prior to Implementation Is
necessary.
Monitoring requirements for so-
lidified material are low In com-
parison with dredge and dispos-
al alternatives. Monitoring can
be readily implemented.
O a M requirements consist of
inspections, groundskeeping,
and maintenance of monitoring
equipment System mainten-
ance is intensive during Imple-
mentation.
Disposal requirements are less
stringent for treated dredge ma-
terial, enhancing approval feasi-
bility However, bench scale
testing is required to demon-
strate effectiveness of solidifi-
cation.
WISHA/OSHA worker protection
required. Alternative compiles
with U.S. EPA's policies for on-
site disposal and permanent re-
duction In contaminant mobility.
May require that shoreline man-
agement aspects be addressed.
Disposal site availability Is un-
certain but feasible. Solidifica-
tion equipment and methods for
arge- scale COM disposal are
currently unavailable.
13-26
-------
TABLE 13-4. EVALUATION SUMMARY FOR RUSTON-PT. DEFIANCE SHORELINE
GO
I
ro
No Action
Short-Term
Protect! veness Low
Timeliness Low
Long-Term
Protect iveness Low
Reduction in Toxicity,
Nobility, or Volume Low
Technical Feasibility High
Institutional
Feasibility Low
Availability High
Long-Term Cleanup
Goal Cost*
Capital
O&M
Total
Long-Term Cleanup Goal
with 10-yr Recovery
Cost3
Capital
O&M
Total
Institutional
Controls
Low
Low
Low
Low
High
Low
High
6
2.869
2.875
6
2.869
2.875
Clamshell/
CAD/
Upland
Disposal
Moderate
Moderate
High
Low
Moderate
Moderate
Moderate
9,523
718
10,241
9.316
707
10.023
Clamshell/
Nearshore
Disposal
Moderate
Moderate
Moderate
Low
Moderate
Moderate
Moderate
14.585
790
15.375
14.266
779
15.045
Hydraulic/
Upland
Disposal
•High
Moderate
Moderate
Low
Moderate
Moderate
High
25.921
1,199
27.120
25,351
1,179
26,530
Cl amshel 1 /
Solidify/
Upland
Disposal
Moderate
Moderate
High
High
Moderate
Moderate
High
39,164
1.143
40,307
38.301
1,124
39,425
a All costs are in $1.000.
-------
for worker exposure. The clamshell dredging/solidification/upland disposal
alternative is also rated moderate because of the increased potential for
worker exposure, as compared with nontreatment alternatives, due to
solidification-related contaminated dredged material handling, longer
implementation periods, and increased air emissions. In spite of the
increased exposure potential, the moderate rating is appropriate because
adequate worker health and safety controls are available.
The hydraulic dredging/upland disposal alternative is rated high for
short-term protectiveness because worker and public exposure potentials
would be minimized by containment of all dredged materials within a pipeline
system. In addition, the habitats that would be compromised for disposal
are of relatively lower sensitivity.
Timeliness--
Because an excessive amount of time is necessary for sediments to
recover naturally, both the no-action and institutional controls alter-
natives are rated low for this criterion. Natural recovery times for all the
indicator compounds would require in excess of 100 yr, even with complete
elimination of contaminant sources (see Section 13.3).
Moderate ratings have been applied to all the remaining alternatives.
For dredging options that involve siting of upland or confined aquatic
disposal facilities, approvals and construction are estimated to require a
minimum of 1-2 yr. Because of the large volume of sediment requiring
remediation, the clamshell/dredging/nearshore disposal option is also rated
as moderate under this criterion. Placement of this material in the Blair
Waterway site would consume well over half its available capacity. The
equipment and methods used to carry out these alternatives require no
development period, and pre-implementation testing is not expected to be
extensive. These factors indicate that the dredge and disposal alternatives
can be implemented in a shorter period of time than if treatment is
involved. Solidification is likely to require extra time for bench-scale
testing and equipment development or modification, although facility siting
and technology development could be conducted concurrently. Treatment of
contaminated sediments in the Ruston-Pt. Defiance Shoreline problem area
would require a minimum of 480 working days even at the maximum production
rate of 1,000 yd3/day.
Long-Term Protect!veness--
The comparative evaluation for long-term protectiveness resulted in
low ratings for the no-action and institutional controls alternatives
because the timeframe for natural recovery is excessive. For the institu-
tional controls alternative, the potential for exposure of resident biota to
contaminated sediments would remain, albeit at declining levels following
implementation of source reductions. The observed adverse biological
impacts would continue.
Moderate ratings were assigned for the nontreatment dredging and
disposal alternatives, including nearshore and upland disposal only, because
13-28
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of potential physicochemical changes due to placing contaminated dredged
material in these disposal facilities. These changes, primarily from new
redox conditions, would tend to alter the migration potential of the
contaminants. Contaminated dredged material testing should provide the
necessary data on the magnitude of these impacts. Based on dredged material
testing, placement in the nearshore facility could be designed to minimize
migration potential by utilizing the appropriate physicochemical environment
(e.g., placement below the low tide level). Although the structural
reliability of the nearshore facilities is regarded as good, the nearshore
environment is dynamic in nature as a result of wave action and tidal
influences. Even though the upland disposal facility is generally regarded
as a more secure option because of improved engineering controls during
construction, there is potential for impacts on groundwater.
The solidification and confined aquatic/upland disposal alternatives
are rated high for long-term protection. Placing material in a confined,
subaquatic environment generally provides a high degree of isolation, with
little potential for exposure to an environment sensitive to the contaminated
dredged material. Although there is uncertainty about potential contaminant
partitioning and groundwater protection for the upland disposal site, these
concerns can be addressed through implementation of adequate engineering
controls during construction and an adequate monitoring program. In
addition, shallow groundwater quality beneath the ASARCO site (assumed to
be the upland disposal site) has already been compromised by past disposal
and operational practices. The high degree of immobilization provided by
solidification of inorganic contaminants substantially increases the long-
term protectiveness of this alternative over dredge and disposal alterna-
tives. However, it should be noted that a maximum grain size of 1 mm has
been suggested for effective encapsulation of contaminants (Long, D., 3 May
1988, personal communication). The deeper areas off the slag fill area
adjacent to the yacht basin have been characterized as containing relatively
coarse sand and slag particles (Parametrix et al. 1988).
Reduction in Toxicity, Mobility, or Volume--
Low ratings have been assigned to all alternatives under this criterion,
except the clamshell dredging/solidification/upland disposal option, which
is rated high. None of the other five alternatives involves treatment of
contaminated sediments. Although the confined aquatic/upland, nearshore,
and upland disposal alternatives isolate contaminated dredged material from
the surrounding environment, the chemistry of the material remains unaltered.
For nearshore and upland disposal alternatives, the mobilization potential
for untreated contaminated dredged material may actually increase with
changes in physicochemical conditions. Without treatment, the toxicity of
contaminated sediments remains at preremediation levels. Contaminated
sediment volumes are not reduced, and may actually increase with hydraulic
dredging options because of suspension of the material in an aqueous slurry.
Solidification of contaminated dredged material prior to disposal
effectively encapsulates inorganic contaminants, thereby reducing mobiliza-
tion potential permanently and significantly. Through isolation in .the
solidified matrix, this process also reduces the effective toxicity of
13-29
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contaminants as compared with nontreatment alternatives. Because the
available data suggest that the organic contaminants present have a high
particle affinity, the process may also be relatively effective in encapsu-
lating these materials. Elutriate tests during bench-scale testing of
solidified contaminated dredged material would be expected to provide data
with which to substantiate or invalidate these conclusions.
Technical Feasibility--
All alternatives except no action and institutional controls are rated
moderate under this criterion. Although feasible, implementation of
dredging alternatives to depths of well over 100 ft in an extremely steep
bathymetric setting is expected to be difficult. The variations in sediment
nature and grain size documented in the interim RI report (Parametrix et al.
1988) may also compromise the effectiveness of the dredging efforts.
Solidification is assigned a moderate rating for technical feasibility
because of the need to conduct bench-scale testing prior to implementation.
Solidification technologies for the treatment of contaminated dredged
material on a large scale are conceptual at this point, although the method
appears to be feasible (Cullinane, J., 18 November 1987, personal communica-
tion) .
High ratings are warranted for the no-action and institutional controls
alternatives because the equipment, technologies, and expertise required for
effective implementation have been developed and are readily accessible.
Although monitoring requirements for the alternatives are considered in
the evaluation process, these requirements are not weighted heavily in the
ratings. Monitoring techniques are well established and technologically
feasible, and similar methods are applied for all alternatives. The
intensity of the monitoring effort, which varies with uncertainty about
long-term reliability, does not influence the feasibility of implementation.
Institutional Feasibility--
The no-action and institutional controls alternatives have been
assigned low ratings for institutional feasibility because compliance with
CERCLA/SARA mandates would not be achieved. Requirements for long-term
protection of public health and the environment would not be met by either
alternative.
Moderate ratings are assigned to the four alternatives requiring
dredging, excavation, or treatment because of potential difficulty in
obtaining agency approvals for disposal sites, or implementation of treatment
technologies. Prior to implementation of the solidification option,
extensive performance testing will probably be required to demonstrate
effectiveness. Agency approvals for this option are expected to require
significant coordination for disposal siting and review for performance
evaluation.
Although several potential nearshore and upland disposal sites have
been identified in the project area, significant uncertainty remains with
13-30
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the actual construction and development of the sites. Although the Blair
Waterway nearshore facility is expected to be available, the large volume of
sediment requiring remediation in this problem area would be expected to
reduce the likelihood of using that site. Although excavation and disposal
of untreated, contaminated sediment is discouraged under Section 121 of
SARA, properly implemented confinement should meet requirements for public
health and environmental protectiveness. Agency approvals are assumed to be
contingent upon a bench-scale demonstration of the effectiveness of each
alternative in meeting established performance goals (e.g., treatability of
dredge water and immobilization of contaminants through solidification).
Availability--
Candidate sediment remedial alternatives that can be implemented using
existing equipment, expertise, and disposal or treatment facilities are
rated high for availability. Because the no-action and institutional
controls alternatives can be readily implemented immediately, they received
a high rating.
Remedial alternatives involving dredging with confined aquatic/upland
and nearshore disposal have been rated moderate because of the uncertainty
associated with disposal site availability. Candidate alternatives were
developed by assuming that a confined aquatic site would be available. The
previously identified potential confined aquatic disposal sites (Phillips
et al. 1985) have sufficient capacity for confinement of the approximately
380,000 yd^ of sediment with arsenic contamination levels below 3,000 mg/kg
(e.g., the Brown's Point site capacity has been estimated at up to
2,000,000 yd^). However, no sites are currently approved for use and no
sites are currently under construction. As indicated previously, the large
volume of sediment requiring remediation significantly diminishes the
likelihood of using the Blair Waterway or other identified potential
nearshore disposal sites.
Alternatives involving upland disposal only have been rated high for
this criterion, based on the assumption that a site could be developed on
the ASARCO property. The feasibility of this option would be enhanced if
disposal site development were coordinated with other site remedial actions.
Cost--
Capital costs increase with increasing complexity (i.e., from no action
to the treatment option). This increase reflects the need to site and
construct disposal facilities, develop treatment technologies, and implement
alternatives requiring extensive contaminated dredged material or dredge
water handling. Costs for conducting the hydraulic dredging/upland disposal
option are significantly elevated over the clamshell dredging/nearshore
disposal option primarily as a result of the additional costs required for
underdrain and bottom liner installation, dredge water clarification, and
use of pipeline boosters to facilitate contaminated dredged material
transport to the upland site. The cost of conducting the solidification
alternative increases as a result of material costs for the process, and
13-31
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associated labor costs for material handling and transport. Dredge water
management costs are also incurred for this option.
A major component of O&M costs is the monitoring requirements associated
with each alternative. The highest monitoring costs are associated with
alternatives involving the greatest degree of uncertainty for long-term
protectiveness (e.g., institutional controls), or where extensive monitoring
programs are required to ensure long-term performance (e.g., confined
aquatic disposal). Costs for monitoring of the alternative including
confined aquatic disposal is significantly higher because of the need to
collect sediment core samples at multiple stations, with each core being
sectioned to provide an appropriate degree of depth resolution to monitor
migration. Nearshore and upland disposal options, on the other hand, use
monitoring well networks requiring only the collection of a single ground-
water sample at each well to assess contaminant migration.
It is also assumed that the monitoring program will include analyses
for all contaminants of concern (i.e., those exceeding long-term cleanup
goals) in the problem area. This approach is conservative and could be
modified to reflect use of key chemicals to track performance. Monitoring
costs associated with the solidification alternative are significantly lower
based on the degree of reduction in contaminant migration potential achieved
by the process.
13.6 PREFERRED SEDIMENT REMEDIAL ALTERNATIVE
Based on the detailed evaluation of the six candidate sediment remedial
alternatives proposed for the Ruston-Pt. Defiance Shoreline, clamshell
dredging with upland disposal of the most highly contaminated material and
confined aquatic disposal of the remaining material has been recommended as
the preferred alternative. Should dredging be designated for areas with
water depths exceeding 100 ft, then use of a bucketwheel dredge is recom-
mended. Because sediment remediation will be implemented according to a
performance-based ROD, the specific technologies identified in this
alternative (i.e., clamshell dredging, upland disposal, confined aquatic
disposal) may not be the technologies eventually used to conduct the
cleanup. New and possibly more effective technologies available at the time
remedial activities are initiated may replace the alternative that is
currently preferred. However, any new technologies must meet or exceed the
performance criteria (e.g., attainment of specific cleanup criteria)
specified in the ROD. This alternative was selected for the following
reasons:
• The alternative protects human health by effectively isolating
contaminated sediments either in an engineered upland
facility or a quiescent subaquatic environment
• Both disposal methods are technically feasible and have been
demonstrated to be effective in isolating contaminated
material
13-32
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• The alternative is consistent with state dangerous waste
regulations that may preclude confined aquatic disposal of
sediments whose arsenic concentrations exceed 3,000 mg/kg (dry
weight)
• The alternative is consistent with the Tacoma Shoreline
Management Plan, Sections 401 and 404 of the Clean Water Act,
and other-applicable environmental regulations
• The volume of contaminated sediment to be disposed of at a
confined aquatic site (approximately 80 percent of the total
volume, or 460,000 yd-*) is compatible with the tentatively
identified disposal facilities; the remaining material
(approximately 20 percent of the total volume, or 115,000 yd^)
could possibly be disposed of at an upland facility at the
ASARCO site
• The costs of developing an upland facility that is secure
and protective of groundwater are justified by the high
concentrations of arsenic in the most highly contaminated
sediments
• Estimated costs for this alternative are approximately
$5 million less than those for the nearshore alternative and
$16 million less than use of upland disposal as the sole
disposal method.
Although this alternative is rated as moderate for most evaluation
criteria, it provides a cost-effective means of addressing sediment
remediation for a large volume of dredged material in a complex environmental
setting. Approximately 575,000 yd^ of sediment will need to be removed and
disposed of for a cost of approximately $9,316,000. The present worth of
30 yr of environmental monitoring and O&M at the disposal sites is estimated
to be $707,000. Therefore, the total estimated present worth of this
alternative is $10,023,000.
The elevations above long-term cleanup goals in this problem area were
among the highest observed in the study area over the largest sediment
surface area. These extremely high contaminant levels warrant the added
degree of protectiveness afforded by the engineering controls of a RCRA-
equivalent upland disposal facility. If elutriate testing of contaminated
dredged material indicates that contaminant partitioning is relatively low,
it may be possible to upgrade ratings for both short- and long-term
protectiveness.
Although some sediment resuspension is inherent in dredging operations,
silt curtains, dredge system modifications, and other engineering controls
would be expected to minimize adverse impacts associated with redistribution
of contaminated dredged material. Dredging within this problem area is
consistent with the Tacoma Shoreline Management Plan. Close coordination
with appropriate federal, state, and local regulatory personnel will be
required prior to undertaking remedial actions.
13-33
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The nearshore disposal alternative was not selected because the volume
of material is more compatible with confined aquatic disposal. The Blair
Waterway Slip 1 disposal area is not large enough to accommodate all
contaminated sediments in the Commencement Bay N/T area, nor ys it appro-
priate for the contaminants in all sediments. Although confined aquatic
disposal cannot be implemented as quickly as nearshore disposal at an
available site, it offers a similar degree of protection at a lower cost.
Solidification/upland disposal was not selected as the preferred
alternative since the timeframe for remedial action would be lengthened
(approximately doubled) and implementation costs would be approximately
4 times as great as those of the preferred alternative. Implementation
would require bench-scale and possibly pilot-scale testing. In addition,
treatment itself would take a considerable period of time (approximately
4 yr), given available equipment and the large volume of contaminated
sediment. Decreased mobility of contaminants due to the stabilization is
not expected to significantly increase long-term protect!veness compared
with selective disposal in the confined aquatic and upland sites.
It is expected that confined aquatic disposal of less-contaminated
sediment coupled with upland disposal of more contaminated sediment will
provide a nearly equivalent level of protection compared with the upland
disposal alternative. In addition, the cost of the latter alternative is
approximately $16 million greater than that of the preferred alternative.
No-action and institutional controls alternatives are ranked high for
technical feasibility, availability, and capital expenditures. However, the
failure to mitigate environmental and potential public health impacts far
outweighs these advantages.
13.7 CONCLUSIONS
The Ruston-Pt. Defiance Shoreline was identified as a problem area
because of the elevated concentrations of inorganic and organic contaminants
in sediments. Arsenic, mercury, and LPAH were selected as indicator
chemicals to assess source control requirements, evaluate sediment recovery,
and estimate the area and volume to be remediated. In this problem area,
sediments with concentrations currently exceeding long-term cleanup goals
cover an area of approximately 1,176,000 yd2, and a volume of 588,000 yd3.
Of the total sediment area currently exceeding cleanup goals, 26,000 yd2 is
predicted to recover within 10 yr following implementation of all known,
available, and reasonable source control measures, thereby reducing the
contaminated sediment volume by approximately 13,000 yd3. The total volume
of sediment requiring remediation is, therefore, reduced to 575,000 yd3-
The primary identified source of problem chemicals to the Ruston-
Pt. Defiance Shoreline is the ASARCO smelter facility. Source control
measures required to correct the identified problems at the facility and
ensure the long-term success of sediment cleanup in the problem area include
the following actions:
13-34
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• Reduce the amount of inorganic contaminants that are present
in the groundwater and that discharge to the waterway
• Continue monitoring at the ASARCO facility outfalls and
implement additional control technologies, if necessary
• Implement surface water runoff and erosion control tech-
nologies to minimize discharges originating from highly
contaminated surface soils identified in the RI
• Conduct additional source investigations to confirm that all
significant sources of problem chemicals have been identified
and controlled
• Implement regular sediment monitoring to confirm sediment
recovery predictions and successful implementation of source
control measures.
It should be possible to control sources sufficiently to maintain
acceptable long-term sediment quality. This determination was made by
comparing the level of source control required to maintain acceptable
sediment quality with the level of source control estimated to be technically
achievable and observed since the shutdown of the smelter. Additional
evaluations to refine these estimates will be required as part of the source
control measures described above. Source control requirements were developed
through application of the sediment recovery model for the indicator
chemicals arsenic, mercury, and HPAH. The assumptions used in determining
source control requirements were environmentally protective. It is
anticipated that more detailed loading data will demonstrate that sources
can be controlled to the extent necessary to maintain acceptable sediment
quality. If the potentially responsible parties demonstrate that implementa-
tion of all known, available, and reasonable control technologies will not
provide sufficient reduction in contaminant loadings, then the area
requiring sediment remediation may be re-evaluated.
Clamshell dredging/confined aquatic/upland disposal was recommended as
the preferred alternative for remediation of sediments not expected to
recover within 10 yr following implementation of all known, available, and
reasonable source control measures. The selection was made following a
detailed evaluation of viable alternatives encompassing a wide range of
general response actions. Because sediment remediation will be implemented
according to a performance-based ROD, the alternative eventually implemented
may differ from the currently preferred alternative. The preferred
alternative meets the objective of providing protection for both human
health and the environment by effectively isolating contaminated sediments
in either an engineered RCRA-equivalent upland facility or at near in situ
conditions in a quiescent, subaquatic environment. Upland disposal of
contaminated wastes has been used extensively throughout the county.
Confined aquatic disposal has been demonstrated to be effective in isolating
contaminated sediments (U.S. Army Corps of Engineers 1988). The high levels
of inorganic contaminant concentrations in sediment in this area appear to
warrant the additional protectiveness afforded by an upland disposal
13-35
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facility. The effects of those high level contaminants (containing a high
percentage of slag particles) is currently being evaluated as part of the
ASARCO RI/FS process through extensive biological and chemical testing. In
the event that these evaluations reveal that the inorganic contaminants are
tightly bound in the slag paniculate matrix, re-evaluation of the need for
a RCRA-equivalent upland disposal facility to meet established performance
goals may be required. The alternative is consistent with the Tacoma
Shoreline Management Plan, Sections 404 and 401 of the Clean Water Act, and
other applicable environmental requirements.
As indicated in Table 13-4, clamshell dredging/confined aquatic/upland
disposal provides a cost-effective means of sediment mitigation for the
large volume of sediment in this problem area. The estimated cost to
implement this alternative is $9,316,000. Environmental monitoring and
other O&M costs at the disposal site have a present worth of $707,000 for a
period of 30 yr. These costs include long-term monitoring of sediment
recovery areas to verify that source control and natural sediment recovery
have corrected the contamination problems in the recovery areas. The total
present worth cost of the preferred alternative is $10,023,000.
Although the best available data were used to evaluate alternatives,
several limitations in the available information complicated the evaluation
process. The following factors contributed to uncertainty:
• Limited data on spatial distribution of contaminants, used to
estimate the area and depth of contaminated sediment
• Limited information with which to develop and calibrate the
model used to evaluate the relationships between source
control and sediment contamination
• Limited information on the ongoing releases of contaminants
and required source control
Limited information
associated costs.
on disposal site availability and
In order to reduce the uncertainty associated with these factors, the
following activities should be performed during the remedial design stage or
addressed in the ASARCO facility RI/FS process:
• Additional sediment monitoring to refine the area and depth of
sediment contamination
• Further source investigations
• Monitoring of sources and sediments to verify the effective-
ness of source control measures
• Final selection of a disposal site.
13-36
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Implementation of source control followed by sediment remediation is
expected to be protective of human health and the environment and to provide
a long-term solution to the sediment contamination problems in the area.
The proposed remedial measures are consistent with other environmental laws
and regulations, utilize the most protective solutions practicable, and are
cost-effective.
13-37
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14.0 SUMMARY OF PREFERRED ALTERNATIVES
Ten candidate alternatives were defined for sediment remedial action
in the Commencement Bay Nearshore/Tideflats study area. Detailed evaluations
of applicable alternatives were performed for each of nine problem areas,
using the most recent U.S. EPA guidance for feasibility studies. Evaluation
criteria were grouped in three general categories: effect .eness, implemen-
tability, and cost. On the basis of this analysis, preferred alternatives
were identified for each problem area. These preferred alternatives are
reviewed in Section 14.1. Factors affecting estimated costs and predicted
recovery of sediment quality are discussed in Sections 14.2 and 14.3,
respectively. Restoration of habitat disturbed by the recommended remedial
activities is addressed in the final subsection.
14.1 PREFERRED ALTERNATIVES
The alternatives that were evaluated for each waterway are identified
in Table 14-1. The preferred alternative selected for each problem area is
also identified. Four categories of preferred alternative were selected:
removal with confined aquatic disposal, removal with nearshore disposal, in
situ capping, and institutional controls.
14.1.1 Removal/Confined Aquatic Disposal
Removal with confined aquatic disposal is recommended as the preferred
alternative for the mouth of Hylebos Waterway, the head of City Waterway,
Wheeler-Osgood Waterway, and the Ruston-Pt. Defiance Shoreline. In all
cases except Ruston-Pt. Defiance, clamshell dredging is recommended, with
confined disposal at a site beyond the immediate problem area. Much of the
sediment requiring remediation in the Ruston-Pt. Defiance area is located at
water depths that exceed the clamshell dredge's working depth of 100 ft. If
removal of sediments from water depths greater than 100 ft is considered,
then use of a bucketwheel dredge might be appropriate. A floating carrier
bucketwheel dredge can be used in water depths greater than 300 ft. In-
waterway confined aquatic disposal is believed to be too restrictive of
future dredging activities in both Hylebos and City Waterways. For
practical and technical considerations, local confined aquatic disposal is
also not recommended in either Wheeler-Osgood Waterway or along the Ruston-
Pt. Defiance Shoreline. It is recommended that contaminated sediments in
Wheeler-Osgood Waterway be removed and replaced with clean sediments to
preserve intertidal habitat in the waterway.
Removal with a clamshell dredged and disposal in a confined offshore
site offers a high degree of protection for both public health and the
environment. Contaminated dredged material will be isolated in an area well
below tidal influence. The long-term reliability of the alternative is
expected to be good, and performance monitoring can be effectively imple-
mented. The dredging and disposal can be implemented in a reasonable
14-1
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TABLE 14-1. ALTERNATIVES EVALUATED FOR EACH PROBLEM AREA
ro
Waterway
Head of Hylebos
Mouth of Hylebos
Sitcum
St. Paul
Middle
Head of City
Wheel er-Osgood
Mouth of City
Ruston-Pt. Defiance
Shorel i ne
No
Action
X
X
X
X
X
X
X
X
X
Institu-
tional
Controls
X
X
X
X
X
X
X
Xa
X
Dredge/
Conf i ned
In Situ Aquatic
Capping Disposal
X
Xa
X
Xa X
X
xa
X Xa
X
xa.c
Dredge/
Nearshore
Disposal
Xa
X
xa
X
xa
X
X
X
X
Hydraul i c
Dredge/
Upland
Di sposal
X
X
X
X
X
X
X
X
X
Clamshell
Cl amshel 1 Dredge/
Dredge/ Solvent
Solidification/ Extraction/
Upland Disposal Upland Disposal
Xb
X
X
X
X
X
X
xb
X
Clamshell
Dredge/
Incineration/
Upland Disposal
Xb
X
X
X
xb
Clamshell
Dredge/
Land
Treatment
X
X
a Preferred alternative.
b Treatment options are combined with solidification for inorganic contaminants to provide a complete alternative to remediation.
c In this case, most dredged sediments would be placed at a confined aquatic disposal site. The most highly contaminated sediments (i.e.. >3,000 mg/kg arsenic),
however, would be taken to an upland disposal facility meeting RCRA standards.
-------
time-frame with available equipment that has proven effective in past similar
operations. It is also cost-effective.
14.1.2 Removal/Nearshore Disposal
Removal with nearshore disposal is recommended as the preferred
alternative for contaminated dredged material in head of Hylebos, Sitcum,
and Middle Waterways. The probable nearshore disposal site is Slip 1 of
Blair Waterway. Clamshell dredging is recommended for the head of Hylebos
and Middle Waterways. Because of the distance between these waterways and
the disposal site, it will be necessary to barge the material to Slip 1.
Clamshell dredging will provide minimal water entrainment and minimal
dispersion of contaminated dredged particles. Hydraulic dredging will
probably be appropriate for Sitcum Waterway because of its proximity to the
disposal site, and dredged material can be pumped directly to the proposed
site. Proper use of silt curtains and a diffuser would limit dispersion of
contaminated dredged particles. Should hydraulic dredging prove to be
impractical during final remedial design, the use of a clamshell dredge
would be acceptable.
This alternative is generally cost-effective and offers a sufficient
degree of long-term protection to public health and the environment to
warrant selection. With disposal below low water and placement of a clean
cap, nearshore disposal would provide an alternative with long-term
reliability. Performance monitoring can be implemented easily and effec-
tively. Also, this alternative can be implemented in a timely manner with
available equipment that has proven effective in the past.
14.1.3 In Situ Capping
In situ capping is recommended as the preferred alternative for
St. Paul Waterway. Because the waterway is shallow and is not designated for
use in commercial shipping, in situ capping would provide a high degree of
protectiveness and may also improve valuable nearshore habitat. By pre-
serving the physicochemical conditions of the contaminated sediments and not
disturbing material, this alternative would result in lowered potential for
migration or redistribution of contaminants compared with alternatives
involving dredging. The weak particle affinities exhibited by the organic
contaminants, however, may facilitate migration potential. Bench-scale
sediment column studies could be conducted to more quantitatively evaluate
contaminant mobilization potential and provide a basis for determining cap
thickness. Capping contaminated sediments in St. Paul Waterway is expected
to provide reliable long-term protection of both public health and the
environment. The alternative can be readily implemented with available
equipment, which has been used as an element of confined aquatic disposal
for other problem areas. Monitoring to evaluate long-term performance of
the cap would not pose technical difficulties. In situ capping also appears
to be cost-effective.
14-3
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14.1.4 Institutional Controls
Institutional controls are recommended as the preferred alternative for
the Mouth of City Waterway. Contaminant concentrations in the Mouth of City
Waterway are less than those concentrations predicted to recover to long-
term cleanup goals within 10 yr. Therefore, institutional controls provide
a cost-effective and environmentally protective remedial alternative.
Monitoring will determine the effectiveness of institutional controls. If
monitoring results suggest that institutional controls are not effectively
lowering contaminant concentrations, a re-evaluation of remedial alternatives
would be warranted.
14.2 COST ANALYSIS
Sediment areas, volumes, and costs of preferred alternatives have been
estimated for long-term cleanup goals, for long-term cleanup goals with
10 yr of natural recovery, and for cleanup to maximum AET levels (Tables 14-2
and 14-3). As shown in Table 14-4, the estimated total volume of sediments
currently exceeding long-term cleanup goals in the nine problem areas is
approximately 2.8 million yd3. If sediments recovering within 10 yr are
excluded the cleanup volume is reduced approximately 36 percent to
1.8 million yd3. The most highly contaminated sediments (i.e., those ex-
ceeding the maximum AET) are estimated to have a volume of 0.7 million yd3.
The total cleanup costs for the entire Nearshore/Tideflats (N/T) site are
estimated to range from $11.3 million (maximum AET levels) to $41.2 million
(long-term cleanup goals).
There is some degree of uncertainty associated with several of the
factors that determine implementation costs. Some of these factors are
identified and discussed in Table 14-5. The first four factors in
Table 14-5 involve uncertainties in surface areas and volumes for cleanup.
Implementation costs for each feasible alternative in each problem area were
estimated for cleanup to both long-term cleanup goals and long-term cleanup
goals with 10-yr recovery. For the preferred alternative, implementation
costs were also estimated for maximum AET level surface areas and volumes.
The possible implications of uncertainties of various cost evaluation factors
(e.g., unit costs for dredging, treatment, and transport; disposal facility
siting and construction; long-term monitoring) can be better understood by
reviewing the detailed cost tables presented in Appendix D.
Additional testing will be required to better define the area and
volume of sediment requiring remediation. At a minimum,, potentially
responsible parties will be required to define the extent and depth of
contamination through additional sediment sampling and either chemical
testing or testing for biological effects. A formal process for defining
cleanup volumes is presented in the Integrated Action Plan for Commencement
Bay (PTI 1988a).
The estimated costs of the preferred alternatives for all nine problem
areas are plotted in Figure 14-1. The plots include initial costs, the
present value of O&M costs, and total estimated costs. Costs are plotted
as a function of volume of contamination for each of the three cleanup
14-4
-------
TABLE 14-2. SUMMARY OF REMEDIAL SEDIMENT SURFACE AREAS AND VOLUMES3
Long-Term Cleanup Goal^
Waterway Area Volume
Head of Hylebos
Mouth of Hylebos
Sitcum
St. Paul
Middle
Head of City
Wheel er-Osgood
Mouth of City
Ruston-Pt. Defiance
Shoreline
TOTAL
381
393
167d
118
126
230
22
27d
1,176
2,640
381
786
167d
236
63
575
11
27d
588
2,834
Long-Term Cleanup Goal
Plus 10-vr Recoverv
Area
217
115
66d
87
114
171
22
0
1,150
1,942
Volume
217
230
66d
174
57
426
11
0
575
1,756
Maximum AETC
Area Volume
9
33
20
90
47
42
1
0
618
860
9
66
20
180
24
104
1
0
309
713
a Areas are reported in units of 1,000 yd2. Volumes are reported in units of
1,000 yd3.
b Sediments with indicator chemical concentrations currently greater than long-term
cleanup goals.
c Sediments with indicator chemical concentrations currently greater than the lower of
either the highest AET or the lowest "severe effects" AET.
d Includes sediment for which biological effects were observed for nonindicator com-
pounds.
14-5
-------
TABLE 14-3. COST SUMMARY FOR PREFERRED ALTERNATIVES
(IN MILLIONS OF DOLLARS)
Waterway
Head of Hylebos
Mouth of Hylebos
Sitcum
St. Paul
Middle
Head of City
Wheel er-Osgood
Mouth of City
Ruston-Pt. Defiance
Shorel i ne
TOTAL
Lonq-Tenn
Preferred Alternative Initial
Clamshell dredge/nearshore
disposal
Clamshell dredge/confined
aquatic disposal
Hydraulic dredge/nearshore
disposal
In situ capping
Cl amshel 1 dredge/nearshore
dl sposal
Cl amshel 1 dredge/con f i ned
aquatic disposal
Cl amshel 1 dredge/conf i ned
aquatic disposal
Institutional controls
Clamshell dredge/upland/confined
aquatic disposal
9.3
6.5
4.1
0.9
1.5
4.5
0.1
0.1
9.5
36.5
Cleanup Goal3
O&M Total
0.6
0.7
0.3
1.3
0.2
0.6
0.0
0.3
0.7
4.7
9.9
7.2
4.4
2.2
1.7
5.1
0.1
0.4
10.2
41.2
Long-Term Cleanup Goal
with 10-Yr Recovery
Initial O&M Total
5.3
1.8
1.6
0.7
1.4
3.3
0.1
0.1
9.3
23.6
0.4
0.3
0.1
1.3
0.2
0.5
0.0
0.3
0.7
3.8
5
2
1,
2.
1.
3.
0.
0,
10.
27.
.7
.1
.7
.0
.6
,8
.1
,4
,0
.4
Maximum AETb
Initial O&M Total
0.1
0.5
0.7
0.7
0.6
0.8
0.1
0.1
5.0
8.6
0.0
0.1
0.1
1.3
0.1
0.1
0.0
0.3
0.5
2.7
0.1
0.6
0.8
2.0
0.7
0.9
0.1
0.4
5.5
11.3
a Sediments with indicator chemical concentrations currently greater than long-term cleanup goals.
b Sediments with indicator chemical concentrations currently greater than the lower of either the highest AET or the lowest "severe
effects" AET.
-------
TABLE 14-4. SEDIMENT CLEANUP SUMMARY FOR COMMENCEMENT BAY
Long-Term Long-Term
Cleanup Cleanup Goal with Maximum
Goala 10-yr Recovery AETb
Total sediment surface area
(million yd2)
Total sediment volume
2.6
2.8
1.9
1.8
0.9
0.7
(million yd3)
Total cost of preferred alternatives
in all nine problem areas (million $)
Initial 36.5 23.6 8.6
Operation and maintenance 4.7 3.8 2.7
Total 41.2 27.4 11.3
a Sediments with indicator chemical concentrations currently greater than
long-term cleanup goals.
b Sediments with indicator chemical concentrations currently greater than
the lower of either the highest AET or the lowest "severe effects" AET.
14-7
-------
TABLE 14-5. FACTORS AFFECTING COST ESTIMATES
Factor
Discussion
Areal extent of contam-
inated sediment
Depth of contamination
Extent of dredging
Cleanup goals
Selection of a preferred
alternative
Cost evaluation factors
Areas of contamination are based on limited
spatial coverage of chemical data. Better
definition of the extent of contamination
could cause costs to increase or decrease.
On the basis of limited available sediment
profile data, a uniform cleanup depth has been
estimated for each problem area. With
improved depth resolution, it may be possible
to identify variable cleanup depths over a
problem area to reduce volumes and costs.
During the remedial design it may be necessary
to define dredging boundaries exceeding the
irregular boundaries that now define the areas
of contamination (e.g., dredging is ordinarily
performed for rectangular cells). This factor
could cause costs to increase.
Changing cleanup volumes based on additional
biological testing during the appeals process
could cause costs to increase or decrease.
Selection of a different preferred alternative
for any problem area would affect the cost.
The preferred alternative could change based
on new technologies, technological improve-
ments, refinement of analytical data, or
improved areal and depth resolution. For each
problem area, the costs of all alternatives
are provided in the FS.
A variety of cost factors are used in the cost
estimation process. For example, the present
value of O&M costs was estimated with a
10 percent discount rate, as prescribed by
U.S. EPA FS guidelines. With a 5 percent
discount rate, the present value of O&M costs
would be about 40 percent greater. Another
factor is the contingency on total costs, for
which 20 percent was used. A greater
contingency factor would increase the total
cost estimates.
14-8
-------
TABLE 14-5. (Continued)
Recovery time calculations The costs that incorporate natural sediment
recovery are directly affected by the factors
that go into the recovery analysis. Two
important factors in the sediment recovery
calculations are the recovery time (e.g.,
10 yr) and percent source control assumed
feasible. Increasing the allowable recovery
time or the estimated feasible level of source
control would tend to reduce cleanup volumes.
Decreasing these factors would tend to
increase cleanup volumes.
14-9
-------
ONS
COS
ONS
10
8
6
4
2
0
2.P
1.5
Head of Hylebos Waterway
Mouth of Hylebos Waterway
Sltcum Waterway
0 50 100 150 200 250 300 350 400
St. Paul Waterway
COST
o
O in
170 180 190 200 210 220 230 240
COST (MILLIONS)
oooeo
O '— M
-------
levels. The highest cos.ts are associated with cleanup to an enrichment
ration of 1.0 (i.e., long-term cleanup goals). These plots can be used to
estimate cleanup costs for volumes or cleanup goals within the range
established for each problem area.
14.3 NATURAL SEDIMENT RECOVERY
The recovery of surface sediments through natural sedimentation has
been evaluated to define areas that will return to acceptable levels of
contamination over a 10-yr time period following implementation of known
available and reasonable source controls. The methods used to evaluate
sediment recovery are provided in Appendix A. Several key factors in the
analysis are presented in Table 14-6. In addition to the factors shown in
Table 14-6, 10 cm was assumed to best represent the average depth of the
mixed layer throughout the Commencement Bay N/T study area.
The calculated enrichment ratio in surface sediments that will recover
in 10 yr is provided in Table 14-6 for each indicator chemical in each
problem area. The recovery calculations suggest that surface sediments with
these enrichment ratios or less will return to enrichment ratios of 1.0 or
less within 10 yr. The effects of source control and the recovery period on
the results are illustrated in Table 14-7. This table can be used to define
areas of recovery within periods of 5, 10, or 25 yr for a range of source
control from 0 to 100 percent. The table should be consulted if it is later
determined that the feasible levels of source control presented in this
document are either too high or too low.
A sensitivity analysis was performed to evaluate the effect of changing
the depth of the mixed layer used in the recovery calculations. The value
of 20 cm was used in the sensitivity analysis, representing the maximum
value of all mixed layer measurements. Increasing the mixing depth from
10 to 20 cm has the same effect as reducing the sedimentation rate used by
50 percent. The 10-yr enrichment ratios would be reduced by either
increasing the mixing depth or decreasing the sedimentation rates. For
example, with 70 percent source control assumed, the 10-yr enrichment ratio
at the mouth of City Waterway would be reduced from 1.52 to about 1.25 by
increasing the mixing depth from 10 cm to 20 cm. Likewise, with 80 percent
source control assumed, the 10-yr enrichment ratio in Sitcum Waterway would
be reduced from 2.91 to 1.78 by such a change. These changes would cause
the 10-yr cleanup volumes to increase. Nevertheless, the 10-cm mixing depth
is believed to be appropriate given the data available.
14.4 HABITAT RESTORATION
Habitat will be disturbed both in areas that are subject to sediment
remediation and in disposal areas. In all, five categories of habitat could
be disturbed:
• Benthic habitat in problem areas
• Intertidal habitat in problem areas
14-11
-------
TABLE 14-6. SEDIMENT RECOVERY FACTORS
Estimated
Sedimentation
Rate Indicator
Problem Area (cm/yr) Chemical
Head of Hylebos 0.77
Mouth of Hylebos 1.77
Sitcum 1.65
St. Paul 0.70
Middle 0.27
Head of City 0.43
Wheel er-Osgood 0.31
Mouth of City 0.67
Ruston-Pt. <0.12
Defiance Shoreline
PCBs
Arsenic
HPAH
PCBs
Hexachloro-
benzene
Copper
Arsenic
4-Methyl phenol
Mercury
Copper
HPAH
Cadmium
Lead
Mercury
HPAH
Zinc
HPAH
Mercury
Arsenic
Mercury
LPAH
Long-Term
Cleanup
Goal9
150
57
17,000
150
22
390
57
670
0.59
390
17,000
5.1
450
0.59
17,000
410
17,000
0.59
57
0.59
5,200
Percent
Source
Control
Assumed1*
70
80
90
60
95
80
80
95
70
70
60
60
60
60
70
70
70
70
95
95
95
10-yr
Enrichment
Ratio0
1.6
1.7
1.9
2.0
4.6
2.9
2.9
1.9
1.2
1.2
1.3
1.3
1.3
1.3
1.2
1.2
1.5
1.5
1.1
1.1
1.1
a Concentration, expressed as ug/kg dry weight for organics and mg/kg dry
weight for metals.
b Average source control level assumed to be attainable within a problem
area.
c Maximum enrichment ratio in surface sediment that will recover (i.e.,
return to 1.0) in 10 yr.
14-12
-------
TABLE 14-7. MAXIMUM ENRICHMENT RATIOS THAT ARE PREDICTED
TO RECOVER TO ACCEPTABLE LEVELS IN A GIVEN TIME PERIOD
Percent
Source
Control
Recovery Period
5 yr 10 yr 25 yr
Head of Hvlebos Waterway
0
10
20
30
40
50
60
70
80
85
90
95
100
0
10
20
30
40
50
60
70
80
85
90
95
100
1.00
1.03
1.07
1.10
1.14
1.18
1.23
1.28
1.33
1.36
1.39
1.42
1.45
St.
1.00
1.03
1.06
1.10
1.14
1.18
1.22
1.27
1.32
1.34
1.37
1.40
1.43
1.00
1.06
1.12
1.19
1.26
1.35
1.46
1.58
1.72
1.80
1.89
1.98
2.09
1.00
1.09
1.20
1.34
1.51
1.73
2.02
2.44
3.07
3.52
4.13
5.00
6.34
5 yr
Recovery Period
10 yr 25 yr
Mouth of Hvlebas
1.00
1.06
1.13
1.21
1.30
1.41
1.53
1.68
1.87
1.97
2.09
2.23
2.38
Paul Waterway
1.00
1.05
1.11
1.18
1.26
1.34
1.44
1.56
1.69
1.77
1.85
1.94
2.04
1.00
1.09
1.20
1.33
1.50
1.71
2.00
2.40
2.99
3.42
3.99
4.78
5.96
1.00
1.01
1.03
1.04
1.05
1.07
1.08
1.09
1.11
1.12
1.13
1.13
1.14
1.00
1.09
1.20
1.33
1.49
1.70
1.98
2.36
2.93
3.34
3.87
4.60
5.68
Waterway
1.00
1.11
1.25
1.42
1.65
1.97
2.45
3.24
4.75
6.21
8.95
16.03
76.73
Middle Waterway
1.00
1.02
1.05
1.07
1.10
1.13
1.16
1.19
1.23
1.25
1.26
1.28
1.30
1.00
1.05
1.11
1.17
1.24
1.32
1.41
1.51
1.63
1.70
1.77
1.85
1.93
Recovery Period
5 yr 10 yr 25 yr
Sitcum Waterway
1.00
1.06
1.13
1.21
1.30
1.40
1.53
1.67
1.85
1.96
2.08
2.21
2.36
Head
1.00
1.02
1.04
1.06
1.08
1.11
1.13
1.16
1.18
1.20
1.21
1.22
1.24
1.00
1.09
1.20
1.33
1.49
1.69
1.97
2.35
2.91
3.30
3.82
4.52
5.55
of Citv
1.00
1.04
1.07
1.12
1.16
1.21
1.26
1.32
1.39
1.42
1.46
1.50
1.54
1.00
1.11
1.25
1.42
1.65
1.97
2.45
3.23
4.74
6.18
8.90
15.85
72.65
Waterway
1.00
1.07
1.15
1.25
1.36
1.49
1.65
1.85
2.11
2.27
2.45
2.66
2.92
Wheeler-Osaood Waterway
Mouth of Citv Waterway
Ruston-Pt. Defiance
0
10
20
30
40
50
60
70
80
85
90
95
100
1.00
1.01
1.03
1.05
1.06
1.08
1.09
1.11
1.13
1.14
1.15
1.16
1.17
1.00
1.03
1.06
1.09
1.12
1.15
1.19
1.23
1.27
1.29
1.32
1.34
1.36
1.00
1.06
1.12
1.19
1.28
1.37
1.48
1.61
1.76
1.85
1.94
2.05
2.17
1.00
1.03
1.06
1.09
1.13
1.17
1.21
1.25
1.29
1.32
1.34
1.37
1.40
1.00
1.05
1.11
1.17
1.24
1.32
1.41
1.52
1.64
1.71
1.78
1.86
1.95
1.00
1.09
1.19
1.32
1.48
1.68
1.95
2.32
2.86
3.23
3.72
4.38
5.33
1.00
1.01
1.01
1.02
1.02
1.03
1.04
1.04
1.05
1.05
1.06
1.06
1.06
1.00
1.01
1.02
1.04
1.05
1.06
1.07
1.09
1.10
1.11
1.12
1.12
1.13
1.00
1.03
1.06
1.09
1.12
1.15
1.19
1.23
1.27
1.29
1.31
1.34
1.36
14-13
-------
• Benthic habitat in confined aquatic disposal areas
• Intertidal habitat in nearshore disposal areas
• Habitats at or adjacent to upland disposal areas.
14.4.1 Benthic Habitat in Problem Areas
Contaminated habitat in problem areas will be disturbed over the short
term. However, over the long term, sediment remediation is designed to
restore benthic habitat to precontamination conditions. The abundance of
benthic organisms should ultimately be similar to their abundance in similar
uncontaminated sites.
14.4.2 Intertidal Habitat in Problem Areas
Some intertidal habitat is likely to be disturbed in each problem area.
Estimates of surface areas and associated sediment volumes that could be
disturbed by remediation efforts for each of the three cleanup levels are
shown in Table 14-8. For dredging alternatives, these habitats will be
restored through replacement with clean fill. Replacement costs have been
included in the remedial cost estimates. In St. Paul Waterway, the
intertidal habitat at the mouth of the waterway may actually be enhanced by
capping activities. Although in all cases habitat will be disturbed over
the short term, the long-term goal of the sediment remediation effort is to
create an improved habitat.
14.4.3 Benthic Habitat in Confined Aquatic Disposal Areas
Benthic communities will be displaced by placement of contaminated
dredged material. However, by capping with clean material, benthic organisms
should be able to return to abundances at or near predisturbance levels.
14.4.4 Intertidal Habitat in Nearshore Disposal Areas
Slip 1 of Blair Waterway is not considered to be an intertidal habitat.
Therefore, through the exclusive use of this site for nearshore disposal,
intertidal habitat should not be affected.
14.4.5 Habitats at or Ad.iacent to Upland Disposal Sites
The only problem area requiring an upland disposal site is the Ruston-
Pt. Defiance Shoreline. Of the sediment requiring remediation, 20 percent
(115,000 yd-*) will require upland disposal. It was assumed that a location
within the ASARCO property could be identified. This property has been in
industrial land use for decades, and development of an upland disposal site
is not expected to cause loss of important upland habitat.
Should an alternative other than the one recommended in this report be
selected as the preferred alternative, it is possible that some upland
habitats would be disturbed. Through proper siting and design this
disturbance could be limited to minimal short-term effects.
14-14
-------
TABLE 14-8. ESTIMATED INTERTIDAL SURFACE AREAS AND VOLUMES
TO BE DISTURBED BY SEDIMENT REMEDIAL ACTION3
Long-Term .
Cleanup Goal
Waterway
Head of Hylebos
Mouth of Hylebos
Sitcum
St. Paul
Middle
Head of City
Wheel er-Osgood
Mouth of City
Ruston-Pt. Defiance
Shore! ine
TOTAL
Area
16
90
0
5
10
5
17
0
32
175
Volume
12
181
0
10
5
13
9
0
16
246
Long-Term Cleanup Goal
Plus 10-vr Recoverv
Area
9
0
0
1
2
5
17
0
32
66
Volume
7
0
0
2
1
13
9
0
16
48
c
Maximum AET
Area
0
0
0
1
1
2
1
0
32
37
Volume
0
0
0
2
1
6
1
0
16
26
a Areas are reported in units of 1,000 yd^. Volumes are reported in units of
1,000 yd3.
b Sediments with indicator chemical concentrations currently greater than long-term
cleanup goals.
c Sediments with indicator chemical concentrations currently greater than the lower of
either the highest AET or the lowest "severe effects" AET.
14-15
-------
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Ecology, Olympia, WA. 37 pp.
Conner, J. 18 November 1987. Personal Communication (phone by Mr. Merv
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Corey, G. 6 August 1987. Personal Communication (phone by Ms. Beth
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Cull inane, J. 18 November 1987. Personal Communication (phone by Mr. Merv
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Davies, D. 2 May 1988. Personal Communication (phone by Ms. Megan White,
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Davies, D. 15 May 1988. Personal Communication (phone by Ms. Megan White,
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Davies, D. 10 June 1988. Personal Communication (phone message to
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Demming, T. 18 April 1988. Personal Communication (phone by Mr. Jerry
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Ecology and Environment. 1987- Site inspection report for Commencement Bay
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El more, D. 22 October 1987. Personal Communication (phone by Ms. Maureen
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ERT. 1987. An interim report focused feasibility study on 3009 Taylor Way,
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history, amounts, update on chlorinated organics. Washington Department of
Ecology, Olympia, WA.
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Olympia, WA.
Fenske, F. 1 May 1987. Personal Communication (phone by Mr. David
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Fenske, F. 4 May 1988. Personal Communication (phone by Ms. Megan White,
Washington Department of Ecology). Washington Department of Ecology,
Olympia, WA.
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Ficklin, J. 2 July 1987. Personal Communication (phone by Ms. Beth
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Ficklin, J. 9 November 1988. Personal Communication (phone by Ms. M. Sue
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Kraft Company, Tacoma, WA.
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practices. Journal of Environmental Engineering Division, Proceedings of
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Gahler, A.R., J.M. Cummins, J.N. Blazevich, R.H. Rieck, R.L. Arp,
C.E. Gangmark, S.V.W. Pope, and S. Filip. 1982. Chemical contaminants in
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EPA-910/9-82-093. U.S. Environmental Protection Agency Region X, Seattle,
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Gerrard, K. 28 October 1987. Personal Communication (phone by Ms. Maureen
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Getchell, C. 23 December 1986a. Personal Communication (interdepartmental
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of Tacoma, Tacoma, WA.
Getchell, C. 23 December 1986b. Personal Communication (interdepartmental
communication to Mr. Ron Robinson, Public Works Department, Tacoma, WA,
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Tacoma, Tacoma, WA.
Getchell, C. 12 October 1987. Personal Communication (interdepartmental
communication to Mr. Chandler Odell, Supervisor, Source Control, regarding
analytical results of dry-weather storm outfall sampling, May-July 1987).
Supervisor, Wastewater Laboratory, Sewer Utility Division, City of Tacoma,
Tacoma, WA. 15 pp.
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Getchell, C. 18 December 1987. Personal Communication (interdepartmental
communication to Mr. Chandler Odell, Supervisor, Source Control, regarding
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October 1987). Supervisor, Wastewater Laboratory, Sewer Utility Division,
City of Tacoma, Tacoma, WA. 15 pp.
Getchell, C. 8 February 1988. Personal Communication (interdepartmental
communication to Mr. Chandler Odell, Supervisor, Source Control, regarding
analytical results of wet- and dry-weather storm outfall sampling, November-
January 1988). Supervisor, Wastewater Laboratory, Sewer Utility Division,
City of Tacoma, Tacoma, WA. 15 pp.
Getchell, C. 19 August 1988. Personal Communication (interdepartmental
communication to Mr. Chandler Odell, Supervisor, Source Control, regarding
analytical results of wet-weather and dry-weather storm outfall sampling,
February-April 1988). Wastewater Treatment Plant Assistant Manager,
Technical Services, City of Tacoma, Tacoma, WA. 15 pp.
Goeoze, D. 22 October 1987. Personal Communication (phone by Ms. Maureen
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Hahlbrock, U. 1983. Bucket wheel excavators in the marine-environment.
Terra et Aga 25:10-21.
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Hart-Crowser & Associates. 1983. Groundwater evaluation. Phase II Report.
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15-6
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Hart-Crowser & Associates. 1985. Hydraulic and contaminant modeling,
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Hart-Crowser & Associates. 1987a. Current situation report on City
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Hartman, R.W. 1 May 1987. Personal Communication (letter to
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Hartman, R.W. 30 June 1987. Personal Communication (letter to Mr. Dave
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Hartman, R.W. 22 October 1987. Personal Communication (phone by Ms. Maureen
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Hartman, R.W. 8 July 1988. Personal Communication (phone by Dr. William
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Hastings, J.W., and K.H. Nealson. 1977- Bacterial bioluminescence. Annu.
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High, 0. No date. Personal Communication (phone by JRB Associates staff,
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Hillus, L. 4 February 1988. Personal Communication (phone by Mr. Merv
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Hoke, D. 22 October 1987. Personal Communication (phone by Ms. Maureen A.
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Holt, J.G. 1977. The shorter Sergey's manual of determinative bacteriology.
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Homer, R.R., and S.R. Wonacott. 1985. Performance evaluation of a
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Hotchkiss, D. 20 April. 1988. Personal Communication (phone by Ms. Megan
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Spattlp WA
James M. Montgomery, Consulting Engineers, Inc. 1985. Water treatment
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Johnson, A. 23 July 1984. Personal Communication (internal memorandum to
Mr. Frank Monahan, Washington Department of Ecology, regarding results of
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Olympia, WA.
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Project 5 (Part 3) for the Commencement Bay Nearshore/Tideflats Remedial
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Washington Department of Ecology, Olympia, WA.
Johnson, A., and D. Norton. 1985b. Metals concentrations in water,
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Johnson, J. 22 October 1987. Personal Communication (phone by Ms. Maureen
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Kennedy/Jenks/Chilton. 1987a. Engineering evaluation of uppermost aquifer,
arsenic migration alternatives. Final Report. Prepared for Pennwalt
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the former Penite Waste Disposal Area, Pennwalt Inorganic Chemicals
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Kozloff, E.N. 1983. Seashore life of the northern Pacific coast. Uni-
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Kuzek, Lt. 22 October 1987. Personal Communication (phone by Ms. Maureen
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Landau Associates. 1984. Report of sampling and testing Hylebos Waterway,
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Landau Associates. 1987. Final groundwater monitoring report, Kaiser wet
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Long, D. 12 April 1988. Personal Communication (phone by Mr. Jerry
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Long, D. 3 May 1988. Personal Communication (phone by Mr. Jerry Portele).
Chem-Fix Technologies, Ventura, CA.
Ludwig, D.D., J.H. Sherrard, and J.M. Betteker. 1985. Implementation
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Virginia Polytechnic Institute and State University, Blacksburg, VA.
Lyman, W.J., A.E. Glazer, J.H. Ong, and S.F. Coons. 1987. An overview of
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Standards, Monitoring and Data Support Division, Washington, DC. Arthur D.
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Malek, J. 17 December 1987. Personal Communication (phone by Mr. Merv
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Chemical contaminants and biological abnormalities in central and southern
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Malins, D.C., B.B. McCain, D.W. Brown, A.K, Sparks, and H.O. Hodgins. 1982.
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Martinac, J.( Jr. 11 November 1987. Personal Communication (phone by
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Massimino, C. 13 May 1988. Personal Communication (phone by Ms. Megan
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McCuen, R.H. 1980. Water quality trap efficiency of storm water management
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McLain, D. 22 October 1987. Personal Communication (phone by Ms. Maureen
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Michelena, T. 4 May 1988. Personal Communication (phone by Ms. Megan
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Mori, R. 13 January 1988. Personal Communication (phone by Mr. Merv
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Morris, J. 18 November 1987. Personal Communication (phone by Mr. Merv
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Morrison, S. 9 June 1987. Personal Communication (phone by Ms. Beth
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Morrison, S. 29 September 1987. Personal Communication (phone by Mr. Merv
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Morrison, S. 4 May 1988. Personal Communication (phone by Ms. Megan White,
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Ecology, Olympia, WA.
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Muehling, B. 1987. Market profile of marine paints. U.S. Environmental
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New York State Energy Research and Development Authority. 1985. Prepared
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Norlund, Mrs. 22 October 1987. Personal Communication (phone by Ms. Maureen
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Norsen. 2 November 1987. Personal Communication (phone by Ms. Maureen A.
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Norton, D. 10 November 1987. Personal Communication (handout at Washington
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Norton, D. 15 April 1988. Personal Communication (memo to Mr. Scott
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Norton, D., and A. Johnson. 1985a. Assessment of log sort yards as metals
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Washington Department of Ecology, Olympia, WA.
Norton, D., and A. Johnson. 1985b. Sources of sediment contamination in
Sitcum Waterway, with emphasis on ores unloaded at Terminal 7. Completion
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Washington Department of Ecology, Olympia, WA.
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Norton, D., and M. Stinson. 1987. Metals concentrations in ASARCO
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Norton, D., M. Stinson, and W. Yake. 1987. Investigation of 4-methylphenol
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NUS. 1983. Feasibility study - Hudson River PCB site, New York. EPA Work
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Nyers, E. 11 November 1987. Personal Communication (phone by Mr. Merv
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Olczak, M. 1987. Preliminary assessment of B&L woodwaste fill. Prepared
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Parametrix. 1986. Tacoma Kraft pulp mill outfall improvements predesign.
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Parametrix, Hart-Crowser & Associates, and TRC Environmental Consultants.
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77 pp.
Parametrix, Hart-Crowser & Associates, and TRC Environmental Consultants.
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Parametrix, Hart-Crowser & Associates, and TRC Environmental Consultants.
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Pemberton, G.S., M.J. Risk, and D.E. Buckley. 1976. Supershrimp: deep
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Puget Sound Water Quality Authority. 1987. Puget Sound water quality
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Raven Systems and Research. 1984. Commencement Bay, Washington Near-
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