PB94-964420
EP A/RODIR08-94/087
December 1994
EP A Superfund
Record of Decision:
Lowry Landfill Superfund Site,
Arapahoe County, CO
3/10/1994
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Hazardous Waste Collection
Information Resource Center
US EPA Region 3
, Philadelphia, PA 19107
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United States Enviromental Protection Agency
Region VIll
999 18th Street - Suite 500
Denver, Colorado 80202-2466
Record of Decision
Lowry Landfill Superfund Site
Arapahoe County, Colorado
March 1994
Printed on Recycled Paper
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Contents
List of Acronyms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xvi
Gl~ of Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx.
1.0
2.0
Declaration for the Record of Decision ...................... 1-1
1.1 Site Name and Location. . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-1
1.2 Statement of Basis and Purpose. . . . . . . . . . . . . . . . . . . . . . .. 1-1
1.3 Assessment of the Site. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-1
1.4 Description of the Selected Remedy. . . . . . . . . . . . . . . . . . . .. 1-1
1.5 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-3
Site Sllmm~ry ...................................... 2-1
2.1 Site Name, Location, and Description. . . . . . . . . . . . . . . . . . .. 2-1
2.2 Area and Topography. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-1
2.3 Natural Resource Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.3.1 Evaluation of Threatened and Endangered Species. . . . .. 2-1
2.3.1.1 Ecological Setting. . . . . . . . . . . . . . . . . .. 2-1
2.3.1.2 Endangered Species. . . . . . . . . . . . . . . . .. 2-2
2.3.2 Evaluation of Wetland Areas ................... 2-3
2.3.2.1 Ecological Setting. . . . . . . . . . . . . . . . . .. 2-3
Cultural Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2-3
Adjacent Land Use ............................... 2-4
Distance to Nearby Populations. . . . . . . . . . . . . . . . . . . . . . " 2-4
Future Land Use and Populations. . . . . . . . . . . . . . . . . . . . .. 2-4
Location in a Floodplain. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
General Surface Water and Ground-Water Resources. . . . . . . . .. 2-6
2.9.1 Surface Water Resources. . . . . . . . . . . . . . . . . . . . .. 2-6
2.9.2 Ground-Water Resources. . . . . . . . . . . . . . . . . . . . .. 2-6
2.9.2.1 Residential Wells. . . . . . . . . . . . . . . . . . .. 2-6
2.9.2.2 Industrial Wells. . . . . . . . . . . . . . . . . . . .. 2-6
2.9.2.3 Municipal Wells. . . . . . . . . . . . . . . . . . .. 2-7
2.10 Surface and Subsurface Features. . . . . . . . . . . . . . . . . . . . . .. 2-7
2.10.1 Structures............................... 2-7
2.10.2 Roads.................................. 2-8
2.10.3 Fencing................................ 2-8
2.10.4 Pipelines and Utility Lines. . . . . . . . . . . . . . . . . . . .. 2-8
2.10.5 Surface Disposal Areas ... . . . . . . . . . . . . . . . . . . .. 2-8
2.10.6 Soil Borrow Areas . . . . . . . . . . . . . . . . . . . . . . . . .. 2-9
2.10.7 Surface Drainage and Sediments. . . . . . . . . . . . . . . .. 2-9
2.10.8 Subsurface Features. . . . . . . . . . . . . . . . . . . . . . . .. 2-9
2.10.8.1 Hydrogeologic Conceptual Model. . . . . . . . . .2-10
2.10.8.2 au 1: Shallow Ground-Water System. . . . . . .2-11
2.4
2.5
2.6
2.7
2.8
2.9
DENlOO14EC4.WPS
111
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Contents (continued)
3.0
4.0
5.0
6.0
Page
2.10.8.3 OU 6: Deep Ground-Water System. . . . . . . . 2-11
Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . . .. 3-1
3.1 Operational History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-1
3.2 History of Site Investigations. . . . . . . . . . . . . . . . . . . . . . . .. 3-2
3.2.1 Site Investigation Activities from 1964 to 1984 ........ 3-2
3.2.2 Preliminary Assessment, Hazard Ranking, and NPL
Listing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.2.3 Phase I RI: February 1985 to April 1986 ........... 3-3
3.2.4 ATSDR Determination. . . . . . . . . . . . . . . . . . . . . .. 3-3
3.2.5 Phase n RI: January 1987 to October 1989 .......... 3-3
3.3 History of CERCLA Enforcement. . . . . . . . . . . . . . . . . . . . .. 3-4
3.3.1 The 1988 Consent Order for OU 1 RIfFS and the 1989
Amended and Restated Consent Order for OU 6 RIfFS.. 3-4
3.3.2 The 1990 Administrative Order on Consent for OUs 2&3
RIfFS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.3.3 The 1991 Consent Order for OUs 4&5 RIfFS. . . . . . . .. 3-5
3.3.4 History of the 1984 Barrier Wall Consent Order, the
1986 Barrier Wall Consent Decree, the 1991 Surface
Removal Action, and the 1993 Modified Consent Decree. 3-6
History of the 1989 Drum Removal Action. . . . . . . . . .. 3-7
PRP Search ............................. 3- 7
Bankruptcy Settlements. . . . . . . . . . . . . . . . . . . . . .. 3-8
De Minimis Settlements. . . . . . . . . . . . . . . . . . . . . .. 3-8
3.3.5
3.3.6
3.3.7
3.3.8
High lights of Community Participation. . . . . . . . . . . . . . . . . . . . .. 4-1
4.1 Community Relations Plan . . . . . . . . . . . . . . . . . . . . . . . . . .. 4-1
4.2 Lowry Landfill Monitoring Committee. . . . . . . . . . . . . . . . . .. 4-1
4.3 Technical Advisory Group. . . . . . . . . . . . . . . . . . . . . . . . . .. 4-1
4.4 Outreach Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.5 Technical Assistance Grant. . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.6 Information Repositories. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Scope and Role of Operable Units. . . . . . . . . . . . . . . . . . . . . . . .. 5-1
Summary of Site Characteristics. . . . . . . . . . . . . . . . . . . . . . . . .. 6-1
6.1 Extent of Contamination in Affected Media. . . . . . . . . . . . . . .. 6-1
6.1.1 OUs 1&6: Shallow Ground Water and Subsurface Liquids,
and Deep Ground Water-Operable Units. . . . . . . . . .. 6-2
6.1.1.1 Sources of Contamination. . . . . . . . . . . . . .. 6-2
6.1.1.2 Nature and Extent of Contamination. . . . . . .. 6-2
DENlOO14EC4.WP5
iv
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Contents (continued)
DENlOO14EC4.WPS
6.2
Page
6.1.1.3 Concentrations of Contaminants. . . . . . . . . .. 6-4
6.1.1.4 Volume Estimates. . . . . . . . . . . . . . . . . .. 6-4
6.1.2 au 2: Landfill Solids. . . . . . . . . . . . . . . . . . . . . .. 6-5
6.1.2.1 Source of Contamination. . . . . . . . . . . . . .. 6-5
6.1.2.2 Nature and Extent of Contamination Within the
Landfill Mass. . . . . . . . . . . . . . . . . . . .. 6-5
6.1.2.3 Concentrations of Contaminants Within the
Landfill Mass. . . . . . . . . . . . . . . . . . . " 6-5
6.1.2.4 Nature and Extent of Contamination Within the
Former Tire Pile Area . . . . . . . . . . . . . . .. 6-6
6.1.2.5 Concentrations of Contaminants Within the
Former Tire Pile Area . . . . . . . . . . . . . . .. 6- 7
6.1.2.6 Volume Estimates. . . . . . . . . . . . . . . . . .. 6-7
6.1.3 au 3: Landfill Gas ........................ 6-7
6.1.3.1 Source of Contamination. . . . . . . . . . . . . .. 6-7
6.1.3.2 Nature and Extent of Contamination. . . . . . .. 6-7
6.1.3.3 Concentrations of Contaminants. . . . . . . . . .. 6-8
6.1.3.4 Volume Estimates. . . . . . . . . . . . . . . . . .. 6-9
6.1.4 au 4: Soil.......... . . . . . . . . . . . . . . . . . . .. 6-9
6.1.4.1 Source of Contamination. . . . . . . . . . . . . .. 6-9
6.1.4.2 Nature and Extent of Contamination. . . . . . .. 6-9
6.1.4.3 Concentrations of Contaminants. . . . . . . . . . . 6-10
6.1.4.4 Volume Estimates .................. .6-12
6.1.5 au 5: Surface Water. . . . . . . . . . . . . . . . . . . . . . . .6-12
6.1.5.1 Past Source of Contamination. . . . . . . . . . . . 6-12
6.1.5.2 Nature and Extent of Contamination. . . . . . . . 6-12
6.1.5.3 Concentrations of Contaminants. . . . . . . . . . .6-13
6.1.5 .4 Volume Estimates. . . . . . . . . . . . . . . . . . . 6-13
6.1.6 au 5: Sediments............ . . . . . . . . . . . . . .6-13
6.1. 6.1 Past Source of Contamination. . . . . . . . . . . . 6-13
6.1.6.2 Nature and Extent of Contamination. . . . . . . . 6-14
6.1.6.3 Concentrations of Contaminants. . . . . . . . . . . 6-14
6.1.6.4 Volume Estimates ...................6-15
Surface and Subsurface Pathways of Migration. . . . . . . . . . . . . . 6-15
6.2.1 Subsurface Liquids to Shallow Ground Water. . . . . . . . . 6-16
6.2.2 Subsurface Liquids and Shallow Ground Water to Surface
Water and Sediments. . . . . . . . . . . . . . . . . . . . . . .6-16
Volatiles from Subsurface Liquids to Landfill Gas ...... 6-17
Landfill Solids to Landfill Gas to Atmosphere. . . . . . . . . 6-17
Contaminated Surface Water to Shallow Ground Water. . . 6-18
Shallow Ground Water to Deep Ground Water. . . . . . . . . 6-18
6.2.3
6.2.4
6.2.5
6.2.6
v
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Contents (continued)
7.0
8.0
Page
Sllmmary of Site Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7-1
7.1 Human Health Risks. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7-2
7.1.1 Chemicals of Concern. . . . . . . . . . . . . . . . . . . . . . .. 7-2
7.1.2 Summary of Exposure Assessment. . . . . . . . . . . . . . .. 7-3
7.1.2.1 Current Exposure. . . . . . . . . . . . . . . . . . .. 7-3
7.1.2.2 Hypothetical Future Exposure ............ 7-3
7.1.2.3 Summary of Toxicity Assessment. . . . . . . . .. 7-7
7.1.2.4 Summary of Risk Characterization. . . . . . . .. 7-9
7.1.2.5 Uncertainty in the Risk Assessment. . . . . . . . . 7-15
7.1. 3 Summary of Lead Risks. . . . . . . . . . . . . . . . . . . . . . 7-15
7.1. 4 Summary of Radiological Risks. . . . . . . . . . . . . . . . . . 7-17
7.1.4.1 Contaminated Media and Exposure. . . . . . . . . 7-17
7.1.4.2 Summary of Toxicity Assessment. . . . . . . . . .7-18
7.1.4.3 Summary of Risk Characterization. . . . . . . . . 7-18
7.1.4.4 Uncertainties....................... 7-19
7.1.5 Summary of Environmental Risks. . .. . . . . . . . . . . . . .7-20
7.1.5.1 Ecological Setting. . . . . . . . . . . . . . . . . . .7-20
7.1.5.2 Ecological Chemicals of Concern. . . . . . . . . . 7-21
7.1.5.3 Exposure Assessment. . . . . . . . . . . . . . . . . 7-21
7.1.5.4 Ecological Effects Assessment. . . . . . . . . . . . 7-22
7.1.5.5 Uncertainties....................... 7-23
7.2 Baseline Risk Assessment Summary. . . . . . . . . . . . . . . . . . . . . 7-24
Description of Remedial Alternatives. . . . . . . . . . . . . . . . . . . . . . .. 8-1
8.1 Cost Estimating Procedures. . . . . . . . . . . . . . . . . . . . . . . . .. 8-2
8.1.1 Respondents' Cost Estimates. . . . . . . . . . . . . . . . . . .. 8-3
8.1.2 EPA's Revised Cost Estimates. . . . . . . . . . . . . . . . .. 8-3
Features Common to All Remedial Alternatives. . . . . . . . . . . . .. 8-3
Interim Remedial Measures. . . . . . . . . . . . . . . . . . . . . . . . .. 8-5
Description of Alternatives. . . . . . . . . . . . . . . . . . . . . . . . .. 8-6
8.4.1 Description of No Action Alternative for all
~~le Units. . . . . . . . . . . . . . . . . . . . . . . . . .. 8-6
8.4.2 OUs 1&6-Shallow Ground Water and Subsurface Liquids,
and Deep Ground Water. . . . . . . . . . . . . . . . . . . .. 8-6
8.4.2.1 Alternative GW-I-No Further Action. . . . . .. 8-7
8.4.2.2 Alternative GW-2-North Boundary (Downgradient)
Containment, Collection, and Treatment. . . . . 8-10
8.4.2.3 Alternative GW-3-North Boundary and Toe of
Landfill Containment, Collection, and
Treatment. . . . . . . . . . . . . . . . . . . . . . . 8-11
8.2
8.3
8.4
DENI OO14EC4. WP5
VI
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Contents (continued)
DEN 1001 4EC4.WPS
8.4.3
8.4.4
Page
8.4.2.4 Alternative GW-4-North Boundary, Toe of Landfill,
and Upgradient Containment, Collection and
Treatment, Plus Multilayered Cap in Landfill
Area . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-12
8.4.2.5 Alternative GW-5 - North Boundary, Toe of
Landfill and Lateral Containment, Collection
and Treatment. . . . . . . . . . . . . . . . . . . . . 8-14
8.4.2.6 Alternative GW-6- North Boundary and Toe of
Landfill Containment, Collection and
Treatment, and Waste-Pit Pumping. . . . . . . . 8-15
8.4.2.7 EPA's Preferred Alternative-Modified Alternative
GW-5-North Boundary, Toe of Landfill, and
Lateral Containment, Collection, and Treatment
plus Upgradient Containment, Collection, and/or
Diversion. . . . . . . . . . . . . . . . . . . . . . . . 8-17
OUs 2&3-Landfill Solids and Gas . . . . . . . . . . . . . . . . 8-18
8.4.3.1 Alternative LFS-2-No Further Action. . . . . . . 8-19
8.4.3.2 Alternative LFS-3 -Clay Cap '.'.."'.'.' 8-20
8.4.3.3 Alternative LFS-4-Drum Removal/Offsite
Disposal. . . . . . . . . . . . . . . . . . . . . . . . 8-21
8.4.3.4 Alternative LFS-6- Drum Removal/Low
Temperature Thermal Desorption/
Stabilization/Disposal ................ 8-22
8.4.3.5 Alternative LFS-7-Landfill Mass Regrading. . . 8-24
8.4.3.6 EPA's Preferred Alternative-Modified Alternative
LFS-4 - Drum Removal/Offsite Disposal/North
Face Cover. . . . . . . . . . . . . . . . . . . . . . 8-25
8.4.3.7 Alternative LFG-2-No Further Action. . . . . . 8-26
8.4.3.8 Alternative LFG-3 -Gas Collection/Enclosed
Flare .......................... 8-27
8.4.3.9 Alternative LFG-5 -Gas Collection with Heat
Recovery. . . . . . . . . . . . . . . . . . . . . . . . 8-29
8.4.3.10 EPA's Preferred Alternative-Modified Alternative
LFG-3 -Gas Collection/Enclosed Flare. . . . . 8-30
OUs 4&5 -Soils, Surface Water, and Sediments. . . . . . . . 8-31
8.4.4.1 EPA's Preferred Alternative-Alternative SOIL-l-
No Further Action. . . . . . . . . . . . . . . . . . 8-32
8.4.4.2 Alternative SOIL-2-Access Restrictions and Dust
Control. . . . . . . . . . . . . . . . . . . . . . . . . 8-33
8.4.4.3 Alternative SOIL-4a Excavation and Landfill
(on site) ........ . . . . . . . . . . . . . . . . . 8-34
Vll
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Contents (continued)
9.0
8.4.4.4
8.4.4.5
8.4.4.6
8.4.4.7
8.4.4.8
8.4.4.9
8.4.4.10
Page
Alternative SOIL-4b, Excavation and Landfill
(off site) . . . . . . . . . . . . . . . . . . . . . . . . . 8-37
EPA's Preferred Alternative-Alternative SW-l-
No Further Action. . . . . . . . . . . . . . . . . . 8-38
EPA's Preferred Alternative-Section 6 Sediments
Alternative SED6-1- No Further Action. . . . . 8-42
Section 6 Sediments Alternative SED6-2-Access
Restrictions. . . . . . . . . . . . . . . . . . . . . . 8-44
EPA's Preferred Alternative-Section 31 Sediments
Alternative SED31-1- No Further Action. . . . 8-45
Section 31 Sediments Alternative SED31-2-Access
Restrictions and Capping. . . . . . . . . . . . . . 8-46
Section 31 Sediments Alternative SED31-3-
Excavation and Landfill. . . . . . . . . . . . . . . 8-48
Summary of the Comparative Analysis of Alternatives. . . . . . . . . . .. 9-1
9.1 OU 1: Shallow Ground Water and Subsurface Liquids and OU 6:
Deep Ground Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9-2
9.1.1 Threshold Criteria. . . . . . . . . . . . . . . . . . . . . . . . .. 9-2
9.1.1.1 Overall Protection of Human Health and the
Environment. . . . . . . . . . . . . . . . . . . . .. 9-2
9.1.1.2 Compliance with ARARs .. . . . . . . . . . . . .. 9-5
9.1.2 Primary Balancing Criteria. . . . . . . . . . . . . . . . . . . .. 9-6
9.1.2.1 Long-Term Effectiveness and Permanence. . . .. 9-6
9.1.2.2 Reduction of Toxicity, Mobility, or Volume
Through Treatment. . . . . . . . . . . . . . . . .. 9-8
9 .1.2.3 Short-Term Effectiveness. . . . . . . . . . . . . .. 9-8
9.1.2.4 Implementability.................... 9-9
9.1.2.5 Cost............................ 9-10
9.1.3 Modifying Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . 9-12
9.1.3.1 State/Support Agency Acceptance
(August 1993) . . . . . . . . . . . . . . . . . . . . . 9-12
9.1.3.2 Community Acceptance. . . . . . . . . . . . . . . . 9-12
9.2 OU 2: Landfill Solids and OU 3: Landfill Gas ............. 9-13
9.2.1 Threshold Criteria. . . . . . . . . . . . . . . . . . . . . . . . . .9-13
9.2.1.1 Overall Protection of Human Health and the
Environment. . . . . . . . . . . . . . . . . . . . . . 9-13
9.2.1.2 Compliance with ARARs . . . . . . . . . . . . . . . 9-15
9.2.2 Primary Balancing Criteria. . . . . . . . . . . . . . . . . . . . .9-15
9.2.2.1 Long-Term Effectiveness and Permanence. . . . . 9-15
DENIOOI4EC4.WP5
vw
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Contents (continued)
9.2.3
9.3
OU 4:
9.3.1
9.3.2
9.3.3
Page
9.2.2.2 Reduction of Toxicity, Mobility, or Volume
Through Treatment. . . . . . . . . . . . . . . . . . 9-16
9.2.2.3 Short-Term Effectiveness. . . . . . . . . . . . . . . 9-17
9.2.2.4 Implementability.................... 9-17
9.2.2.5 Cost............................ 9-18
Modifying Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . 9-20
9.2.3.1 State/Support Agency Acceptance. . . . . . . . . . 9-20
9.2.3.2 Community Acceptance. . . . . . . . . . . . . . . . 9-20
Soil and OU 5: Surface Water and Sediments. . . . . . . . . . 9-21
Threshold Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . 9-21
9.3.1.1 Overall Protection of Human Health and the
Environment. . . . . . . . . . . . . . . . . . . . . . 9-21
9.3.1.2 Compliance with ARARs ... . . . . . . . . . . . . 9-22
Primary Balancing Criteria. . . . . . . . . . . . . . . . . . . . . 9-22
9.3.2.1 Long-Term Effectiveness and Permanence. . . . . 9-22
9.3.2.2 Reduction of Toxicity, Mobility, or Volume
Through Treatment. . . . . . . . . . . . . . . . . . 9-23
9.3.2.3 Short-Term Effectiveness. . . . . . . . . . . . . . . 9-24
9.3.2.4 Implementability.................... 9-24
9.3.2.5 Cost............................ 9-25
Modifying Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . 9-27
9.3.3.1 State/Support Agency Acceptance. . . . . . . . . . 9-27
9.3.3.2 Community Acceptance. . . . . . . . . . . . . . . . 9-27
10.0 Documentation of Significant Changes. . . . . . . . . . . . . . . . . . . . . . . 10-1
11.0 Selected Sitewide Remedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-1
11.1 General Components of the Selected Sitewide Remedy. . . . . . . . . 11-1
11.2 Remedy for Shallow Ground Water and Subsurface Liquids and
Deep Ground Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-3
11.2.1 Containment Components (Barrier Walls and Collection
Systems) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-5
11.2.1.1 Performance Standards and Points of
Compliance. . . . . . . . . . . . . . . . . . . . . . 11- 7
11.2.1.2 Contingency Measures. . . . . . . . . . . . . . . . . 11-8
11.2.2 Treatment Component. . . . . . . . . . . . . . . . . . . . . . . . 11-9
11.2.2.1 Performance Standards and Points of
Compliance. . . . . . . . . . . . . . . . . . . . . . 11-9
11.2.2.2 Contingency Measures. . . . . . . . . . . . . . . . 11-10
11.3 Remedy for Landfill Solids. . . . . . . . . . . . . . . . . . . . . . . . . 11-10
11.3.1 Performance Standards and Points of Compliance. . . . . . 11-11
DENlOO14EC4.WPS
IX
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Contents (continued)
Page
11.4 Remedy for Landfill Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-12
11.4.1 Performance Standards and Point of Compliance. . . . . . 11-13
11. 4.2 Contingency Measures. . . . . . . . . . . . . . . . . . . . . . 11-14
11.5 Remedy for Soils and Surface Water and Sediments. . . . . . . . . . 11-14
11.5.1 Performance Standards and Points of Compliance. . . . . . 11-15
11.5.2 Contingency Measures. . . . . . . . . . . . . . . . . . . . . . 11-16
11.6 Cost of the Selected Sitewide Remedy. . . . . . . . . . . . . . . . . . . 11-17
12.0 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-1
12.1 Protection of Human Health and the Environment. . . . . . . . . . . . 12-1
12.2 Compliance with ARARs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-3
12.3 Cost Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-4
12.3.1 Shallow Ground Water and Subsurface Liquids (aU 1) and
Deep Ground Water (aU 6) . . . . . . . . . . . . . . . . . . . 12-4
12.3.2 Landfill Solids (au 2) ....................... 12-4
12.3.3 Landfill Gas (au 3) . . . . . . . . . . . . . . . . . . . . . . . . . 12-5
12.3.4 Soil (au 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-5
12.3.5 Surface Water (aU 5) . . . . . . . . . . . . . . . . . . . . . . . . 12-6
12.3.6 Sediments (OU 5) .......................... 12-6
12.3.7 Selected Sitewide Remedy. . . . . . . . . . . . . . . . . . . . . 12-6
12.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies (or Resource Recovery Technologies) to the
Maximum Extent Practicable. . . . . . . . . . . . . . . . . . . . . . . . 12-7
12.4.1 Long-Term Effectiveness and Permanence. . . . . . . . . . . 12-7
12.4.2 Reduction of Toxicity, Mobility, or Volume Through
Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-9
12.4.3 Short-Term Effectiveness. . . . . . . . . . . . . . . . . . . . . . 12-9
12.4.4 Implementability.......................... 12-11
12.4.5 Cost.................................. 12-12
12.4.6 State Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . 12-13
12.4.7 Community Acceptance. . . . . . . . . . . . . . . . . . . . . . 12-13
12.5 Preference for Treatment as a Principal Element. . . . . . . . . . . . 12-14
13.0 Responsiveness SIImm9ry for Operable Units 1&6 ............... 13-1
13.1 Response to Oral Comments on the Proposed Plan for Operable
Units 1&6 Shallow Ground-Water and Subsurface Liquids and
Deep Ground-Water Operable Units Lowry Landfill Public Meeting
December 9, 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1
13.2 Response to Written Comments on the Proposed Plan for Operable
Units 1&6 Shallow Ground-Water and Subsurface Liquids and
Deep Ground-Water Operable Units August 1993 . . . . . . . . . . . 13-83
13.2.1 EPA's Response to Comments from Citizens Against Lowry
Landfill Richard Schelin, Chairman. . . . . . . . . . . . . 13-83
DENlOO14EC4.WPS
x
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Contents (continued)
13.2.2
13.2.3
13.2.4
13.2.5
13.2.6
13.2.7
13.2.8
13.2.9
13.2.10
Page
EPA's Response to Comments from City of Aurora. . . . 13-89
EP A's Response to Comments from Colorado Department
of Health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-96
EP A's Response to Comments from East Cherry Creek
Valley Water and Sanitation District. . . . . . . . . . . . . 13-97
EPA's Response to Comments from William G.
Kennedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-104
EPA's Response to Comments from the Lowry
Coalition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-11 0
EPA's Response to Comments from Robert Velton,
Pemex, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-111
EPA's Response to Comments from United States
Department of Interior, Fish and Wildlife Service. . .. 13-112
EPA's Response to Comments from Waste Management
of Colorado, Inc., Chemical Waste Management, Inc.,
and the City and County of Denver. . . . . . . . . . .. 13-113
EPA Response to comments from Wilbur A. Young. .. 13-124
14.0 Responsiveness Snmm;lry for OUs 2&3 and 4&5 . . . . . . . . . . . . . . . . 14-1
14.1 Response to Oral Comments Proposed Plan Public Meeting
Lowry Landfill Solids/Gas Operable Units (OUs 2&3) and
Soils/Surface Water and Sediments Operable Units (OUs 4&5)
September 21, 1993 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1
14.2 Response to Written Comments Proposed Plan Lowry Landfill
Solids/Gas Operable Units (OUs 2&3) and Soils/Surface
Water and Sediments Operable Units (OUs 4&5) . . . . . . . . . . . 14-13
14.2.1 Response to Written Comments
Hadden and Bonnie Robinson. . . . . . . . . . . . . . . . . 14-13
14.2.2 Response to Written Comments
Wilbur Young, November 1, 1993 Letter. . . . . . . . . . 14-15
14.2.3 Response to Written Comments
East Cherry Creek Valley Water and
Sanitation District (ECCV) . . . . . . . . . . . . . . . . . . . 14-17
14.2.4 Response to Written Comments
Wilbur Young, November 5, 1993 Letter. . . . . . . . . . 14-22
14.2.5 Response to Written Comments
City of Aurora. . . . . . . . . . . . . . . . . . . . . . . . . . 14-23
14.2.6 Response to Written Comments City and County of Denver
(Denver), Waste Management of Colorado, Inc. (WMC),
and Chemical Waste Management, Inc. (CWM) . . . . . . 14-24
15.0 Bibliography
DENlOO14EC4.WPS
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-1
Xl
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2-1
2-2
2-3
2-4
3-1
4-1
Tables
Page
Wildlife Species Observed Within or Near the Lowry Site. . . . . . . . . . . . 2-21
Plant Species Noted Within the Vicinity of the Lowry Site. . . . . . . . . . . . 2-22
Potentially Occurring Threatened and Endangered Species
Within or Around the Lowry Site. . . . . . . . . . . . . . . . . . . . . . . . . .2-24
Well Inventory Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-25
De Minimis Settlement, Consent Order Docket No. CERCLA VID-93-04
Effective August 28, 1992 and De Minimis Settlement Consent Order
Docket No. CERCLA VID-93-21 Effective June 2, 1993 ........... 3-11
Lowry Landfill Superfund Site Fact Sheets and Updates. . . . . . . . . . . .. 4-4
6-1 Summary of Chemical Concentration Data for Waste Pit Liquids Well
Points and Shallow Ground-Water Monitoring Wells in the Source Area .. 6-25
6-2 Summary of Chemical Concentration Data for Downgradient Weathered
Dawson Monitoring Wells Outside of the Source Area . . . . . . . . . . . . . 6-29
6-3 Summary of Chemical Concentration Data for Downgradient Unweathered
Dawson Monitoring Wells Outside the Source Area . . . . . . . . . . . . . . . 6-32
6-4 Summary of Chemical Concentration Data for Deep Ground-Water
Monitoring Wells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-35
6-5 Summary of Chemical Concentration Data for Upgradient Monitoring Wells
Outside the Source Area ............................... 6-37
6-6 Summary of Chemicals Detected in Unsaturated Solids Within the
Landfill Mass. . . . . . . . . . . . . . . . . . . . . . . . . . . ; . . . . . . . . . .6-39
6-7 Summary of Chemicals Detected in Unsaturated Solids Within the
Former Tire Pile Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-44
6-8 Methane Concentrations in Perimeter Gas Monitoring Wells. . . . . . . . . . . 6-49
6-9 Landfill Gas Data Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-50
6-10 Sewage Sludge ApplicationlLeachate Injection Area (Group 1) Soils
Data Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-51
6-11 Sewage Sludge Application (Group 2) Soils Data Summary. . . . . . . . . . . 6-53
6-12 Leachate Spraying Area (Group 3) Soils Data Summary. . . . . . . . . . . . . 6-54
6-13 Chemicals Detected in Surface Soil Samples in the Tire Pile Area . . . . . . . 6-55
6-14 Subsurface Soil Data Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-57
6-15 Surface Water Data Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-58
6-16 Summary of Chemicals Detected in Sediments in Section 6 ........... 6-59
7-1
7-2
Minimum/Maximum Concentrations of Contaminants of Concern. . . . . . . 7-26
Ground-Water Exposure Point Concentrations for the Hypothetical Future
Onsite Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-29
DEN 1 00 1 4EC4.WPS
Xll
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Tables (continued)
Page
7-3 Subsurface Soil and Landfill Gas Exposure Point Concentrations. . . . . . . . 7-31
7-4 Surface Soil Exposure Point Concentrations for the Hypothetical Future
Onsite Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-33
7-5 Surface Water and Sediment Exposure Point Concentrations for the
Hypothetical Future Onsite Residential Setting. . . . . . . . . . . . . . . . . . 7-35
7-6 RME Exposure Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-37
7-7 Toxicity Values for Chemicals with Carcinogenic Effects. . . . . . . . . . . . 7-39
7-8 Toxicity Values for Chemicals with Noncarcinogenic Effects. . . . . . . . . . 7-41
7-9 COCs Without Toxicity Values. . . . . . . . . . . . . . . . . . . . . . . . . . . .7-45
7-10 Summary of Quantified Site Risks Based on Hypothetical Future Onsite
Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-46
7-11 Comparison of Subsurface Soil Maximum Detected Concentrations to
Carcinogenic Risk-Specific Values and Noncarcinogenic Reference
Concentrations in the Future Onsite Residential Setting. . . . . . . . . . . . . 7-49
7-12 Comparison of Exposure Point Concentrations of Landfill Gas Within the
Landfill Mass to Carcinogenic Risk-Specific Values and Noncarcinogenic
Reference Concentrations in the Future Onsite Residential Setting. . . . . . 7-51
7-13 Comparison of Modeled Exposure Point Concentrations Assuming a Cracked
Slab to Carcinogenic Risk-Specific Values and Noncarcinogenic Reference
Concentrations in the Future Off site Residential Setting. . . . . . . . . . . . 7-52
7-14 Cumulative Total Risk for the Hypothetical Future On site Residential
Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-53
7-15 Default Parameters Used in UptakelBiokinetic Model. . . . . . . . . . . . . . . 7-54
7-16 Risk Assessment Radionuclides ............................ 7-55
7-17 Summary of Radiological Risk from Ingestion of Ground Water at the RME
Future Onsite Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . 7-56
7-18 Comparison of Maximum Detected Subsurface Soil Concentrations to
Carcinogenic Risk-Specific Values at the RME for the Future Onsite
Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-57
7-19 Summary of Radiological Risk from Exposure to Surficial Soil at the RME
Future Onsite Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . 7-58
7-20 Summary of Radiological Risk from Exposure to Sediments at the RME
Future Onsite Residential Setting. . . . . . . . . . . . . . . . . . . . . . . . . . 7-59
7-21 Summary of Radiological Risk at the RME Future Onsite Residential
Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-60
7-22 Potentially Occurring Threatened and Endangered Species Within or
Around the Lowry Site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-61
7-23 Constituents Eliminated on the Basis of Relative Toxicity. . . . . . . . . . . . 7-62
7-24 Maximum Detected Concentrations of Ecological Chemicals of Concern. . . 7-63
8-1
ARARs for OUs 1&6 ..................................8-50
DENlOO14EC4.WPS
xiii
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Tables (continued)
Page
8-2
8-3
ARARs for OUs 2&3 .................................. 8-59
ARARs for OUs 4&5 .................................. 8-67
11-1 Selected Sitewide Remedy ARARS ...................... . . . 11-22
11-2 Ground-Water Compliance Boundary Performance Standards
Sitewide Remedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-33
11-3 Ground-Water Point of Action Boundary Standards. . . . . . . . . . . . . . . 11-38
11-4 Surface Water Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-41
11-5 Air Quality Performance Standards Sitewide Remedy. . . . . . . . . . . . . . 11-46
11-6 Landfill Gas Point of Action Boundary Standards. . . . . . . . . . . . . . . . 11-49
11-7 Landfill Gas Compliance Boundary Performance Standards
Sitewide Remedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-50
11-8 Cost Estimate Summary Selected Sitewide Remedy. . . . . . . . . . . . . . . 11-51
13-1 Lowry Landfill, Arapahoe County, Colorado
Operable Units 1&6, Proposed Plan,
Effect of Discount Rate on Cost Estimates. . . . . . . . . . . . . . . . .. 13-121
14-1 Chemical Concentration Data Summary. . . . . . . . . . . . . . . . . . . . . . 14-49
DENl0014EC4.WPS
XlV
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1-1
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
3-1
6-1
6-2
6-3
6-4
6-5
6-6
7-1
Figures
Page
Lowry Landfill Combined Sitewide Remedy. . . . . . . . . . . . . . . . . . .. 1-5
The Lowry Site and DADS Facility Location. . . . . . . . . . . . . . . . . . . . 2-12
Current Zoning in the Vicinity of the Lowry Site. . . . . . . . . . . . . . . . . 2-13
Major Land Uses in the Vicinity of the Lowry Site. . . . . . . . . . . . . . . . 2-14
EXpected Future Land Use in the Vicinity of the Lowry Site. . . . . . . . . . 2-15
Ground-Water Supply Wells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-16
Cross-Section Through the Denver Basin ......................2-17
Drinking Water Supply Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . .2-18
Lowry Landfill Site Surface Features. . . . . . . . . . . . . . . . . . . . . . . . . 2-19
Schematic of Hydrogeologic Setting. . . . . . . . . . . . . . . . . . . . . . . . .2-20
Approximate Waste Pit, Tires, and Sludge Application Area Locations. . . . 3-10
Approximate Waste-Pit Locations (1965-1980) and Well Points Where
Non-Aqueous Phase Liquids were Observed. . . . . . . . . . . . . . . . . . . 6-19
Extent of Contaminated Shallow Ground Water. . . . . . . . . . . . . . . . . . 6-20
Extent of Contaminated Deep Ground Water. . . . . . . . . . . . . . . . . . . . 6-21
General Source and Extent of Contamination Within Unsaturated Solids Within
the Former Tire Pile Area .............................. 6-22
General Source and Extent of Contamination From Landfill Gases . . . . . . . 6-23
Potential Sources of Soil Contamination. . . . . . . . . . . . . . . . . . . . . . .6-24
Selection Criteria for the Chemicals of Potential Concern. . . . . . . . . . . . 7-25
11-1 Lowry Landfill Combined Sitewide Remedy. . . . . . . . . . . . . . . . . . . 11-19
11-2 Ground-Water Compliance Boundary and Ground-Water Action
Boundary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-20
11-3 Landfill Gas Compliance and Point of Action Boundaries. . . . . . . . . . . 11-21
..........................
13-106
13-107
13-1 Lowry Landfill OUs 2&3 Area
13-2 Lowry Landfill OUs 4&5 Area
..........................
DEN 1 001 4EC4.WP5
xv
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AAL
AOCs
APEN
ARARs
ASC
ATSDR
Aurora
AWQC
BNA
CAA
CALL
CCD
CDC
CDD/CDF
CDH
CDI
CDOW
CPDES
CERCLA
CPR
cfs
CIN
CHWA
CLP
CNAP
COC
COPC
COSA
CWA
CWM
CWP
DADS
Denver
DQOs
EA
EEICA
EPA
of
FEMA
FIT
FS
DENlOO14EC4.DEN
List of Acronyms
allowable ambient levels
Administrative Orders on Consent
Air Pollution Emission Notice
applicable or relevant and appropriate requirements
Additional Site Characterization
Agency for Toxic Substances and Disease Registry
City of Aurora
Ambient Water Quality Criteria
base-neutral acid
Clean Air Act
Citizens Against Lowry Landfill
City and County of Denver
Center for Disease Control
chlorinated dibenzo-p-dioxin and dibenzofurans
Colorado Department of Health
Chronic Daily Intake
Colorado Division of Wildlife
Colorado Pollution Discharge Elimination System
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
Code of Federal Regulations
cubic feet per second
Citizen's Information Network
Colorado Hazardous Waste Act
Contract Laboratory Program
Colorado Natural Areas Program
chemicals of concern
chemicals of potential concern
Colorado Occupational Health and Safety
Clean Water Act
Chemical Waste Management, Inc.
Conceptual Work Plan
Denver Arapahoe Disposal Site
City and County of Denver
data quality objectives
Ecological Assessment
Engineering Evaluation/Cost Analysis
United States Environmental Protection Agency
degrees Fahrenheit
Federal Emergency Management Agency
Field Investigation Team
feasibility study
xvi
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ft/ day
ft!/yr
FWPCA
GMP
GW
GWI'P
gpm
HEAST
HEW
III
HLA
HQ
HRS
HSWA
HVOC
IDE
IRIS
IRM
kg
I
LIDNAPLs
LFS
LFG
LLMC
LOAEL
Lowry Site
MCLG
MCL
p.g
p.glkg
Metro
mg/kg
mph
NAAQS
NC
NCP
ND
NESHAPs
NOAEL
NOV
NPL
NRC
NRHP
NSPS
O&M
DEN1OO14EC4.DEN
feet per day
cubic feet per year
Federal Water Pollution Control Act
gas monitoring probes
ground water
ground-water treatment plant
gallons per minute
Health Effects Assessment Summary Table
United States Department of Health, Education, and Welfare
Hazard Index
Harding Lawson Associates
Hazard Quotient
Hazard Ranking System
Hazardous and Solid Waste Amendments
hazardous volatile organic chemicals
Initial Data Evaluation
Integrated Risk Information System
interim remedial measure
kilograms
liter
low/dense non-aqueous phase liquids
landfill solids
landfill gas
Lowry Landfill Monitoring Committee
Lowest Observed Adverse Effect Level
Lowry Landfill Superfund Site
maximum contaminant level goal
maximum contaminant level
microgram
microgram per kilogram
Metro Wastewater Reclamation District
milligram per kilogram
miles per hour
National Ambient Air Quality Standards
not calculated
National Contingency Plan for Oil and Hazardous Substances Pollution
not detected
National Emissions Standards for Hazardous Pollutants
No Observed Adverse Effects Level
Notice of Violation
National Priorities List
Nuclear Regulatory Commission
National Register for Historic Places
New Source Performance Standards
operation and maintenance
XVll
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OSHA
OSWER
OUs
OU 1
OU2
OU3
OU4
OU5
OU6
PA
PAG
PAHs
PCBs
pCiIL
PEA
POA
POTW
ppb
ppm
PRPs
QAlQC
RA
RAO
RAGS
RCRA
RID
RI
RIlFS
RME
ROD
SAPI
SARA
scfm
scfltnlyr
SED
SF
SOW
SQL
SRU
STC
SVOC
SW
SWA
SWRA
TAG
DEN 1 OO14EC4.DEN
Occupational Safety and Health Administration
Office of Solid Waste and Emergency Response
openwle units
Shallow Ground Water and Subsurface Liquids Operable Unit
Landfill Solids Operable Unit
Landfill Gas Operable Unit
Soils Operable Unit
Surface Water and Sediments Operable Unit
Deep Ground Water Operable Unit
Preliminary Assessment
Policy Advisory Group
polynuclear aromatic hydrocarbons
polychlorinated biphenyls
picocuries per liter
Preliminary Endangerment Assessment
Point of Action
Publicly Owned Treatment Works
parts per billion
parts per million
potentially responsible parties
quality assurance/quality control
Risk Assessment
remedial action objectives
Risk Assessment Guidance for Superfund
Resource Conservation and Recovery Act of 1976
reference dose
remedial investigation
remedial investigation/feasibility study
reasonable maximum exposure
Record of Decision
Southeast Area Planning Initiative
Superfund Amendments and Reauthorization Act of 1986
standard cubic feet per minute
solid waste cubic feet per ton per year
sediment (abbreviation for sediment alternative number)
slope factors
Statement of Work
Sample Quantification limit
Site Review and Update
Storage Technology Corporation
semivolatile organic compounds
surface water
Solid Waste Act
Surface Water Removal Action
Technical Advisory Group
XVUl
-------
TAG
TBC
TCLP
TEF
TEL
USC
UCL
USFWS
USGS
VOC
WMC
WRIS
DENlOO14EC4.DEN
Technical Assistance Grant
to be considered
toxicity characteristic leaching procedure
Toxicity Equivalent Factors
threshold effects exposure units
United States Code
Upper Confidence Limit
United States Fish and Wildlife Service
United States Geological Survey
volatile organic compounds
Waste Management of Colorado, Inc.
Wildlife Resource Information System (CDOW)
XIX
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Glossary of Terms
Admini~tive Order: An agreement between EP A and one or more potentially respon-
sible parties whereby the potentially responsible party or parties agree to perform or pay
the cost of site investigations or cleanup.
Admini~tive Record: A file that is established and maintained by the lead agency and
contains all the documents used by EP A to make a decision on the selection of a remedial
action. The administrative record is available for public review and a copy is established
at or near the site, usually at one of the information repositories.
Alluvium: Sedimentary deposits from streams or rivers.
Applicable Requirements: Those cleanup standards, standards or control, and other
substantive requirements, criteria or limitations promulgated under federal environmental
or state environmental or facility siting laws that specifically address a hazardous
substance, pollutant, contaminant, remedial action, location, or other circumstance found
at a CERCLA site. Only those state standards that are identified by a state in a timely
manner and that are more stringent than federal requirements may be applicable.
Aquifer: A geologic formation, group of formations, or part of a formation capable of
yielding a significant amount of ground water to wells or springs.
Baseline Risk Assessment (Baseline RA): Evaluates the potential risks to human health
if nothing is done to remediate a site or eliminate the risks. The Baseline RA considers
current use and hypothetical future use of the site.
Capital Costs: The costs of items such as buildings, equipment, engineering, and
construction.
CERCLA: The Comprehensive Environmental Response, Compensation, and Liability
Act of 1980, as amended by the Superfund Amendments and Reauthorization Act of
1986.
Chemicals of Concern: The most prevalent and toxic site-related chemicals.
Co-Disposal: A technique used at the Lowry Site to dispose of wastes. Liquid industrial
wastes were deposited into unlined trenches or pits, and municipal refuse was added to
soak up the liquids.
Compliance Boundary: The boundary at the Lowry Site where chemical-specific
remediation levels and performance standards must be met.
DEN 1001 4EC4.WPS
xx
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Contingency Plans: Plans that detail the action to be taken in response to a remedy
component failure.
Deep Ground Water (Operable Unit 6): All ground water below the shallow ground
water (below the separation layer) to the top of the Pierre Shale, underlying the Laramie-
Fox Hills aquifer.
Enclosed Flare: A piece of equipment (a burner) used to bum landfill gas after
collection; the burner and flame are enclosed.
Excess Lifetime Cancer Risk: The incremental probability of an individual developing
cancer over a lifetime as a result of exposure to a potential carcinogen. A cancer risk of
1 x 10-' is one additional case of cancer (over background levels) per million people
gexposed (a one in a million chance of having cancer). The NCP specifies that 1 x 1~
is an acceptable risk level for multiple contaminants (NCP 300.430[e][2][i][A][2]). EPA
uses a 1 x 10"' to 1 x 10-' risk level as a "target range" within which to manage risk at
Superfund sites.
Exposure: Contact of a chemical with the outer boundary of a human (skin, nose,
mouth, skin punctures and lesions) (EPA 1992, Guidelines for Exposure Assessment;
Notice, EPA, Federal Register 57[104); 22888-22938, May 29, 1992).
Exposure Parameter: Factors such as body weight, breathing rate, or time/activity that
may be needed to quantify (calculate) human exposure to a contaminant.
Exposure Pathway: The course a chemical or physical agent takes from a source to a
receptor. An exposure pathway describes a unique mechanism by which an individual or
population is exposed to chemicals or physical agents at or originating from a site.
Exposure pathway includes a source or release from a source, an exposure point, and an
exposure route. If the exposure point differs from the source, the transport/exposure
medium (such as air) or media (in cases of intermedia transport, such as water to air) are
also included (EPA 1989, Risk Assessment Gu.idancefor Superfund, Vol/, Human Health
Evaluation Manual [pan A), Office of Emergency and Remedial Response,
EPA/540/l-89/002).
Exposure Point: A geographical location of potential contact between a receptor and a
chemical or physical agent, e.g., a child ingesting soil containing PCBs within the sewage
sludge application/leachate injection area (EPA, 1989, Risk Assessment Guidancefor
Superfund, Vol/, Human Health Evaluation Manual [Pan A), Office of Emergency and
Remedial Response, EPA/540/l-89/002).
Exposure Point Concentration: Concentration at the point where receptors may be
exposed.
DENlOO14EC4.WPS
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Exposure Route: The way a chemical or physical agent comes in contact with a
receptor, that is, ~alation, ingestion, dermal contact, e.g., inhalation by a hypothetical
future resident of vinyl chloride in landfill gas contained within a home onsite (EPA.
1989. Risk Assessme1ll Guidance/or SupeTjund. Vol I. Humon Health Evaluation Manual
[part A). Office 0/ Emergency and Remedial Response. EPA/540/1-89/(02).
Exposure Setting: A combination of potential land uses and exposure routes that
describes the ways by which a specific type of receptor can contact contaminants, that is,
residential setting, occupational setting, recreational setting.
Feasibility Study (FS): A study undertaken to develop and evaluate options for remedial
action. The FS emphasizes alternative analysis and is generally performed concurrently
and in an interactive fashion with the remedial investigation (RI), using data gathered
during the RI. The RI data are used to define the objectives of the response action, to
develop remedial action alternatives, and to undertake an initial screening and detailed
analysis of the alternatives. The term also refers to a report that describes the results of
the study.
Former Tire Pile Area: The approximately 3D-acre area in Section 6 of the Lowry Site
from which approximately 8 million old tires were removed.
Fund or Trust Fund: The Hazardous Substance Superfund established by Section 9507
of the Internal Revenue Code of 1986.
Ground Water: As defined by Section 101(12) of CERCLA, water in a saturated zone
or stratum beneath the surface of land or water.
Hazard Ranking System (HRS): The method used by EPA to evaluate the relative
potential of hazardous substance releases to cause health or safety problems, or ecological
or environmental damage.
Hydrogeologic: Relating to the science of hydrogeology, which studies the interactions
among ground water and geologic formations.
Intake: The measure of exposure expressed as the mass of a chemical that crosses an
outer boundary of a human or the chemical per unit body weight per unit time, i.e.,
milligrams of chemical per kilogram of body weight per day.
Institutional Controls: Rules, regulations, laws, or covenants that may be necessary to
assure the effectiveness of a cleanup alternative. Examples of institutional controls
include, but are not limited to, deed restrictions, zoning controls, and access restrictions.
Interim Remedial Measures: An early action taken to control a release or threatened
release of hazardous substances.
DENlOO14EC4.WPS
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Landf"ill Gas (Operable Unit 3): Gas generated at the Lowry Site resulting from
degradation of the landfill solids and chemical constituents volatilized from contaminant
sources such as waste pit liquids, leachate, ground water, surface water (including
unnamed creek and Pond 3; Pond 4 will be included if it is in existence), surface and
subsurface soils, and solids (saturated and unsaturated).
Landf"ill Solids (Operable Unit 2): For the solids media, "unsaturated" is defmed as
material, excluding saturated solids within the waste pits, that is above ground water
associated with the shallow ground water at the Lowry Site. The solids media include
materials located within the Section 6 area that has received or will receive solid wastes
and the area fonnerly covered with tires. Leachate is defined as the liquids generated
during consolidation and/or degradation of the landfill solids or through interaction of
water that percolates through the solids media. Leachate within the solids media is
included as part of the Landfill Solids OU media. The solids media also includes:
.
Unsaturated municipal solid waste (MSW) (e.g., household refuse).
.
Unsaturated industrial waste, including drums and their contents.
.
Buried and partially buried tires within the unsaturated zone.
.
Unsaturated solids contaminated by the migration of waste pit fluids or
leachate.
.
Unsaturated solids located within waste pits.
.
Publicly-owned treatment works (POTW) sludge and sludge from industrial
treatment plants disposed of in the landfill within the unsaturated zone.
.
Hospital wastes disposed of in the landfill within the unsaturated zone.
.
Unsaturated subsurface and surface soils within the Landfill Solids OU
area.
.
Unsaturated low-level radioactive wastes. These wastes were reportedly
disposed of in pits near the southeast corner of Section 6.
.
Zones of saturated solids located above the shallow ground water
(perched), excluding saturated solids within the waste pits.
Leachate: Contaminated liquids that result from the degradation of refuse or from water
percolating through refuse.
DENlOOI4EC4.WPS
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National Priorities List (NPL): The list, compiled by EPA pursuant to CERCLA
Section 105, of uncontrolled hazardous substance releases in the United States that are
priorities for long-term remedial evaluation and response.
Net Present Worth: An analysis of the current value of all costs. Net present worth is
calculated based on a 3O-year time period and a 5 % interest rate.
North Face: The north end of the former landfill that is sloped.
Onsite: The areal extent of contamination and all suitable areas in very close proximity
to the contamination necessary for implementation of the response action.
Operable Unit: A term used to describe certain portions of a Superfund site. An
operable unit may be established based on a particular type of contamination,
contaminated media (e.g., soils, water), source of contamination, and/or geographical
location.
Operation and Maintenance: Measures required to maintain the effectiveness of the
selected remedy.
Parts per billion (ppb)/parts per million (ppm): Units commonly used to express low
concentrations of contaminants. For example, I ounce of trichlorethylene (TCE) in
1 million ounces of water is 1 ppm; I ounce of TCE in I billion ounces of water is
1 ppb.
Point of Action Boundary: The boundary at the Lowry Site where specific performance
standards must be achieved. The purpose of the PDA boundary is to trigger early
remedial actions, so that contaminants do not migrate beyond the compliance boundary.
Potentially Responsible Party (PRP): An individual or company (such as owners, oper-
ators, transporters, or generators of hazardous waste) potentially responsible for, or con-
tributing to, the contamination problems at a Superfund site.
Proposed Plan: A document that summarizes EP A's preferred cleanup strategy, the
rationale for the preference, and alternatives presented in the detailed analysis of the
feasibility study. The Proposed Plan solicits public review and comment on all alterna-
tives under consideration.
Reasonable Maximum Exposure (RME): The RME is the highest exposure that is
reasonably expected to occur at a site. It is the product of a few upper-bound exposure
parameters with primarily average or typical exposure parameters so that the result
represents an exposure that is both protective and plausible, exposure point concentration
and exposure frequency and duration, that are a mix of distributions (averages, 95th
percentile, etc.) to reflect a 90th percentile.
DENlOO14EC4.WPS
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Receptor: Any organism (such as humans, terrestrials, wildlife, or aquatic) potentially
exposed to chemicals of concern.
Record of Decision (ROD): A public document that explains the remedial action plan
for a Superfund site or operable unit. A ROD serves three functions:
.
It certifies that the remedy selection process was carried out in accordance
with CERCLA and, to the extent practicable, with the NCP
.
It describes the technical parameters of the remedy, specifying the
treatment, engineering, and institutional components, as well as
remediation goals
.
It provides the public with a consolidated source of information about the
site and the chosen remedy, including the rationale behind the selection
.
The ROD also provides the framework for the transition into the next
phase of the remedial process, Remedial Design (RD)
Relevant and Appropriate Requirements: Those cleanup standards, standards of
control, and other substantive requirements, criteria or limitations promulgated under
federal environmental or state environmental or facility siting laws that, while not
'"applicable" to a hazardous substance, pollutant, contaminant, remedial action, location,
or other circumstance at a CERCLA site, address problems or situations sufficiently
similar to those encountered at the CERCLA site that their use is well suited to the
particular site. Only those state standards that are identified in a timely manner are more
stringent that federal requirements may be relevant and appropriate.
Remedial Action (RA) or Remedy: Those actions consistent with a permanent remedy
taken instead of, or in addition to, removal action in the event of release or threatened
release of a hazardous substance into the environment, to prevent or minimize the release
of hazardous substances so that they do not migrate to cause substantial danger to present
or future public health or welfare or the environment. The tenn includes, but is not
limited to, such actions at the location of the release as storage, confinement, perimeter
protection using dikes, trenches, or ditches, clay cover, neutralization, cleanup of
released hazardous substances and associated contaminated materials, recycling or reuse,
diversion, destruction, segregation of reactive wastes, dredging or excavations, repair or
replacement of leaking containers, collection of leachate and runoff, onsite treatment or
incineration, provision of alternative water supplies, any monitoring reasonably required
to assure that such actions protect the public health and welfare and the environment and,
where appropriate, post-removal site control activities.
Remedial Action Objectives (RAOs): Objectives developed by EPA at individual
Superfund sites that, in connection with chemical-specific remediation goals and
performance standards define acceptable levels of risk.
DENlOO14EC4.WPS
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Remedial Design (RD): The technical analysis and procedures which follow the
selection of remedy for a site and result in a detailed set of plans and specifications for
implementation of the remedial action.
Remedial Investigation (RI): A process undertaken to determine the nature and extent
of the problem presented by the release. The RI emphasizes data collection and site
characterization, and is generally performed concurrently and in an interactive fashion
with the feasibility study. The RI includes sampling and monitoring, as necessary, and
the gathering of sufficient information to determine the necessity for remedial action and
to support the risk assessment evaluation of remedial alternatives.
Resource Conservation and Recovery Act (RCRA): A FederaIlaw that requires safe
and secure procedures to be used in treating, transporting, storing and disposing of
hazardous wastes.
Respondent: Identifies the party entering into an Administrative Order on Consent
(AOC or Consent Order) with EPA.
Sediments (Operable Unit 5): Sediments in Sections 6 and 31 at the Lowry Site are
defined as unconsolidated deposits of particulates that originated from the weathering of
rocks and organic matter and were transported by water and deposited in drainage
pathways. If a particulate is not a sediment or a landfill solid as defined in OU 2, it is
defined as a soil.
Settling Defendant: Identifies the party entering into a Consent Decree with the
Department of Justice (DOl) and EPA.
Shallow Ground Water and Subsurface Liquids (Operable Unit 1):
.
Ground water within the alluvium and weathered bedrock in the upper
Dawson formation. Weathered bedrock is that portion of the Dawson
Formation, nearest to the ground surface, that has had an increase in its
ability to transmit ground water because of the action of the physical and
chemical processes. This portion of the Dawson Formation is more similar
to the overlying alluvial aquifer than the underlying unweathered Dawson
with respect to its ability to transmit ground water.
Waste Pit Liquids. Liquids that are within the waste pits.
.
.
Subsurface Leachate and Infiltration. Subsurface leachate is defined to be
all liquids that emanate from the waste pits, waste pit solids, and waste pit
refuse that are subsurface. Infiltration is water that enters into the ground
through the soil surface.
DEN 1 OO14EC4.WPS
XXVI
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.
Saturated subsurface solids, including:
Soils that are below the water table
Saturated waste pit solids
Saturated soils adjacent to waste pits
Saturated refuse below the shallow ground-water table
Soils (Operable Unit 4): Soils at the Lowry Site are defined as consolidated and
unconsolidated material consisting essentially of mineral and organic matter above the
water table.
Subtitle C: A program under RCRA that regulates the management of hazardous waste
from the time it is generated until its ultimate disposal.
Subtitle D: A program under RCRA that regulates the management of solid waste.
Superfund Amendments and Reauthorization Act of 1986 (SARA): Amendments to
CERCLA, enacted on October 17, 1986.
Surface Water (Operable Unit 5): At the Lowry Site, surface water originates from
precipitation, ground-water discharge or leachate seeps and occurs on the surface of the
site in drainage subbasins, including the unnamed creek.
Surface Water Removal Action (SWRA): A system at the Lowry Site that separates
normal precipitation in the unnamed creek from contaminated leachate that previously
surfaced in the creek bed. The contaminated leachate is collected in the system and sent
to the onsite treatment facility.
TU'e Monorill: An excavation used at the Lowry Site to contain tire shreds.
Toe of the Fonner Landrill: The northernmost edge of the fonner landfill.
Vertical Migration: The ability of media such as water, to move vertically upwards or
downwards through various subsurface strata.
DENlOO14EC4.WPS
xxvn
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Section 1.0
Declaration for the Record of Decision
-------
Section 1.0
Declaration for the Record of Decision
1.1 Site Name and Location
Lowry Landfill
Arapahoe County, Colorado
1.2 Statement of Basis and Purpose
This decision document presents the selected remedy for the Lowry Landfill Superfund
site (the Lowry Site), in Arapahoe County, Colorado, chosen in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), and, to the extent practicable, the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP). This decision is based on the administrative record
for this Site.
The State of Colorado concurs with the selected remedy.
1.3 Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the selected remedy in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare, or the environment.
1.4 Description of the Selected Remedy
The selected sitewide remedy is composed of selected alternatives for the six operable
units (OUs) identified at the Lowry Site. The sitewide remedy includes operation of
elements of the interim remedial measures at the Lowry Site and the Surface Water
Removal Action, which includes the ground-water barrier wall/treatment facility. All six
of the operable units identified at the Lowry Site (and described in this ROD) are
addressed in the selected sitewide remedy. The selected sitewide remedy addresses the
potential risks identified at the Site through containment, collection, and treatment. The
primary threats at the Lowry Site are posed by: landfill gas; waste-pit liquids; contami-
nated ground water; and buried drums, drum contents, and contaminated soils within the
former tire pile area.
Contaminated ground water will be addressed by containment, collection, and treatment,
utilizing an onsite treatment plant. Landfill gas will be addressed by containment,
DENlOOlS397.WP5
I-I
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collection, and treatment using enclosed flare technology. Contaminated seepage and
surface water are addressed through a drainage and underground collection system in the
unnamed creek area as part of the Surface Water Removal Action. The response action
identified for the former tire pile area will address principal threats (drums, drum
contents, and contaminated soils) through treatment and offsite disposal to reduce the tox-
icity, mobility, and volume of contaminants. Landfill mass solids and soils are low-level
threats at the Lowry Site and are addressed through containment.
Major components of the remedy (as shown in Figure 1-1) include:
DENlOOI5397.WP5
.
Continued operation of the existing ground-water barrier wall, collection
system, and ground-water treatment plant (the Surface Water Removal
Action [SWRA]). The existing ground-water treatment plant may be
upgraded to increase the capacity of the treatment system and to treat more
concentrated liquids from the toe of the landfill, or a new ground-water
treatment plant may be constructed to accomplish the same objectives.
.
Installation of a ground-water extraction system at the toe of the landfill
mass.
.
Construction and operation of underground barrier walls and ground-water
collection systems on the east and west sides of the Lowry Site.
.
Implementation of a ground-water monitoring program along the circumfer-
ence of the point of action (POA) boundary to detect future releases of
contaminants to the east, west, north, and south.
.
Construction and operation of an approximately 50-foot-deep upgradient
ground-water containment, collection, and diversion system along the
southern perimeter of the Lowry Site.
.
Annual treatment of approximately 6.4 million gallons of contaminated
ground water from the new barrier wall and collection systems and the
_existing barrier wall using either the existing ground-water treatment plant,
an upgraded treatment plant, or a new ground-water treatment plant.
.
Implementation of a long-term, sitewide ground-water monitoring program
to assess remedy compliance for the shallow ground-water system and
potential impacts to deep ground water.
.
Monitoring to detect future releases of contaminants to the ground water.
Should releases be detected, corrections to the containment systems would
be made with the potential for additional extraction wells and/or expansion
of the barrier system, and/or other technologies to restrict off site ground-
water migration.
1-2
-------
.
Excavation, removal, and treatment within the former tire pile area, of
surface and subsurface drums, contaminated soils, and waste pits.
.
Landfill gas collection using interior and perimeter collection systems and
an enclosed flare for treatment.
.
Installation of a perimeter gas monitoring system to detect potentiallandf1ll
gas migration. Should migration be detected, corrections to the system
would be made with the potential for installation of additional extraction
wells to restrict off site landfill gas migration.
.
Placement of an additional two (2) feet of cover on the north face of the
landfill mass.
.
Continued maintenance of the landfill mass cover.
.
Construction of wetlands to mitigate loss of wetlands areas from SWRA
construction activities within unnamed creek.
.
Surface-water monitoring to allow detection of future releases of contami-
nants to surface water.
.
Visual monitoring of actual and potential soil erosion.
.
Establishment of institutional controls to limit access to the Lowry Site,
prohibit such activities as construction on the Lowry Site, and prohibit the
use of water beneath the Lowry Site or in the immediate vicinity of the
Lowry Site. Offsite institutional controls shall serve as an additional
measure of protection to enhance the effectiveness of the selected remedy
and to act as preventative measures to preserve the implementability and
effectiveness of any of the selected remedy contingency measures that EP A
determines must be implemented at the Lowry Site.
.
A review of the selected remedy at the Lowry Site no less often than each
5 years after the initiation of the remedial action to assure continued
protection of human health and the environment.
1.5 Statutory Determinations
The selected sitewide remedy is protective of human health and the environment, com-
plies with Federal and State requirements that are legally applicable or relevant and
appropriate to the remedial action, and is cost effective. This remedy utilizes permanent
solutions and alternative treatment technologies to the maximum extent practicable.
Components of the selected sitewide remedy satisfy the statutory preference for remedies
DENlOOlS397.WPS
1-3
-------
that employ treatment that reduce toxicity, mobility, or volume as a principle element.
The size of the landfill mass and inaccessibility of the waste pits, located within and
underneath the landfill mass (exclusive of those in the former tire pile area), precludes a
remedy in which all contaminants could be excavated and effectively treated. Therefore,
consistent with the NCP and EP A guidance Conducting Remedial lnvestigations/
Feasibility Studies/or CERCLA Municipal Landfill Sites (EPA OSWER Directive
9355.3-11, February 1991), containment is selected to address the low-level threat from
the landfill mass and the primary threats from the waste pits within the landfill mass area.
Because treatment of these threats was not found to be practicable, this portion of the
selected sitewide remedy does not satisfy the statutory preference for treatment.
Principal threats (drums, drum contents, contaminated soils, and waste pits) in the former
tire pile area will be addressed through excavation, treatment, and disposal. Conse-
quently, this component of the remedy satisfies the statutory preference for treatment as a
principal element of the remedy.
Because this remedy will result in hazardous substances remaining on the Lowry Site
above health-based levels, a :review will be conducted no less often than each 5 years
after the initiation of the remedial action to assure that the remedy continues to provide
adequate protection of human health and the environment.
William P.~' ~ef:f::1:::!
U.S. Environmental Protection Agency, Region vm
9r-~L.-~
Thomas P. Looby, D. r, Office of Environment
State of Colorado Department of Health
7Pq/9~
March 10, 1 94
DENlOOlS397.WPS
1-4
-------
Gate
.t4DrllLlt4G ~REA
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c,\)?'?' Existin.g Ground-Water
Treatment Plant\ ....
. _£a_~Jt~_1L~~~:~JY~~~ '-
...
/
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AVENUE
Section 31
/
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/
\
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" lA!~
/
I I
I I r
I I I
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\ / Collection
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\ I at Toe 01
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" > . -, ~,
,,!)~:~~~~.": '~.: .
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: Collection and lor
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EAST QUINCY AVENUE
LEGEND:
---- Landfill Boundary (Fence Line)
Note: Lcx:ation of remedy .
components shown are approximate.
Figure 1-1
LOWRY LANDFILL COMBINED SITEWIDE
REMEDY
LOWRY RECORD OF DECISION
DEN Graphllowry ROD/166
1-5
-------
Section 2.0
Site Summary
-------
Section 2.0
Site Summary
2.1 Site Name, Location, and Description
The Lowry Landfill Superfund Site (the Lowry Site) is located in the western three-
quarters of Section 6, Township 5 South, Range 65 West in unincorporated Arapahoe
County, Colorado, approximately 15 miles southeast of the City and County of Denver
and 2 miles east of Aurora, near the intersection of East Quincy Avenue and Gun Club
Road; the street address is 3500 South Gun Club Road, Denver, Colorado. The Lowry
Site consists of 480 acres, and is a portion of the Denver Arapahoe Disposal Site
(DADS), owned by the City and County of Denver (Denver) and operated by Waste
Management of Colorado, Inc. (WMC). DADS consists of Sections 4, 6, and 9, Town-
ship 5 South, Range 65 West and Sections 31 and 32, Township 4 South, Range 65 West
(Figure 2-1).
2.2 Area and Topography
The Lowry Site consists of gentle slopes on the north half of the section and a topo-
graphic high on the south half of the section caused by past landfilling activities
(Figure 2-1).
2.3 Natural Resource Use
The Lowry Coalition conducted an evaluation of potentially protected resources as part of
the OUs 1&6 Remedial Investigation/Feasibility Study (RIfFS). The area for which the
evaluation was conducted includes the landfill located north of Quincy Avenue and east of
Gun Club Road, and all of Section 6, Range 65W, Township 5S, and the south half of
Section 31, Range 65, Township T4S. This area is referred to as the "project area" in
the following text.
2.3.1 Evaluation of Threatened and Endangered Species
2.3.1.1 Ecological Setting
The Lowry Site is located in gently rolling short-grass prairie characteristic of the Great
Plains physiographic province. The land is largely undisturbed native prairie, disturbed
weedy prairie, and areas of unirrigated small grain crops.
Habitats within the Lowry Site boundaries have been disturbed by past and ongoing land-
fill disposal activities. Aquatic habitats within the Lowry Site boundaries are limited and
lack the capacity to support fish. Habitats in Section 6, east of the Lowry Site, are
DEN 1001 S399.WPS
2-1
-------
primarily native prairie with an intermittent riparian corridor. Habitats on the south half
of Section 31, noIth of the Lowry Site, include stripped prairie, the Command Post,
fallow fields, native prairie, weeded, disturbed prairie, and a wetland along Murphy
Creek.
2.3.1.2 Endangered Species
Endangered species that may be present in the vicinity of the Lowry Site, specifically the
bald eagle, peregrine falcon, whooping crane, black-footed ferret, and Federal endan-
gered species candidates, are discussed in the following paragraphs. No specific
occurrences of listed candidate species have been recorded within 1 mile of the Lowry
Site.
Tables 2-1, 2-2, and 2-3 list the wildlife, plant, and threatened and endangered species,
respectively, observed or occurring on the Lowry Site or in the vicinity of the Lowry
Site.
The United States Fish and Wildlife Service (USFWS) lists the bald eagle (Haliaeetus
leucocephalus) as an endangered species in Colorado. Bald eagles are spring and autumn
migrants, but uncommon winter residents in the vicinity of the Lowry Site. However,
they are common winter residents in suitable nearby habitats. The Lowry Site and adja-
cent lands are not an important area for bald eagles. Individual eagles have been seen
irregularly in the vicinity of the Lowry Site, but these birds are generally flying through
the area. The USFWS is not aware of any recent bald eagle sightings. However, a
golden eagle nest has been identified at the intersection of Smoky Hill and Gun Club
Road.
The peregrine falcon (Falco peregrinus) is a Federal and Colorado endangered species.
The gently rolling prairie, on and around the Lowry Site, is not suitable peregrine falcon
habitat. There are no suitable nest sites closer than downtown Denver. Airspace in the
vicinity of the Lowry Site may be used by migrating peregrines; however, it is more
likely that migrants would follow the Front Range (18 miles to the west) for their spring
and autumn migrations. The Lowry Site vicinity does not offer any potentially suitable
habitat for the peregrine falcon.
Whooping cranes (Grus americana) are one of the rarest of all North American endan-
gered species. Colorado has historically been outside the normal range of the species,
except for stragglers migrating between breeding grounds in Canada and wintering
grounds in Texas. Habitats adjacent to, and in the vicinity of, the Lowry Site provide a
suboptimal crane habitat. There are no large wetlands or water bodies present to provide
the horizontal visibility required for secure roosting.
DENlOO1S399.WP5
2-2
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Black-footed ferrets (Mustela nigripes) have historically been associated with the range of
prairie dogs (Cynomys ludovicianus) throughout the Great Plains, semi-arid grasslands,
and mountain basins of North America. The Lowry Site and adjacent areas occur within
the general historic range of the black-footed ferret; however, no black-footed ferret
sightings have been confmned in Colorado in recent years.
Federal candidate species are sensitive wildlife species currently under consideration by
the USFWS for addition to the threatened and endangered species list.
2.3.2 Evaluation of Wetland Areas
The following evaluation includes a description of the ecological setting, wetland iden-
tification and mapping, and a description of the wetlands on or near the Lowry Site,
including a delineation of specific types of wetland vegetation along Murphy Creek in
Section 31 and the unnamed creek drainage in Section 6, and an estimate of acreages for
each wetland vegetation type.
2.3.2.1 ~cological Se~ng
The study area used for the wetlands evaluation is within the southern half of Section 31,
Township 4S, Range 65W, and Section 6, Township 5S, Range 65W. No natural perma-
nent surface-water source exists within the study area. The land is largely native prairie
and areas of dryland crops. Short-grass prairie and dryland crop-field also characterizes
much of the area to the north, south, and east of the Lowry Site.
The Lowry Site is drained by unnamed creek, which is an intermittent stream. Most
habitats within the Lowry Site have been disturbed by past landfilling or ongoing disposal
activities. The irregular topography of the Lowry Site produced by landfill grading
activities has created two small basins which collect water from precipitation events.
Wetlands plant species along the unnamed creek drainage in Section 6 include cattail
(Typha lanfolia and T. angustifolia), three-square (Scirpus americana), and fox-tail barley
(Hordeum jubatum).
During the construction of the SWRA, a total of 0.87 acre of wetlands was disturbed. As
part of the sitewide remedy, an equal amount of wetlands will be created in another
location near the Lowry Site.
2.4 Cultural Resources
During August 1989, an intensive survey of approximately 400 acres of the Lowry Site
was performed to identify and evaluate cultural resources for the National Register of
Historic Places (NRHP) by the Lowry Coalition. The work was conducted to comply
with requirements and responsibilities under the National Historic Preservation Act of
DENlOO15399.WPS
2-3
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1966, as amended, and its implementing regulations (36 CFR Part 800). No resources
were identified for inclusion in the NRHP.
2.5 Adjacent Land Use
Current zoning and land uses by Arapahoe County in the vicinity of the Lowry Site are
presented in Figures 2-2 and 2-3. No residences are located on site.
The areas immediately surrounding the Lowry Site are zoned for agricultural use and
mixed use. Much of the area surrounding the Lowry Site is undeveloped and used pri-
marily for cattle ranching and grazing. Some sections are used for production of dryland
(no irrigation) winter wheat. A few homes are scattered on these farms and ranches in
the areas around the Lowry Site. Two older homes are located roughly one-third and
two-thirds of a mile west of the Lowry Site on East Quincy Road.
2.6 Distance to Nearby Populations
A few subdivisions have been built in unincorporated areas near the Lowry Site. Dove
Hill is a small subdivision approximately I mile south of Section 6. The Trail Ridge,
Park View, and Parborough subdivisions are located a1?out 2 miles southwest.
The most intensive nearby urban and residential development is Within the corporate
limits of the City of Aurora, approximately 2 miles west and north of the Lowry Site.
Gun Club Estates and Thunderbird Estates are located 3 and 4 miles north of Section 6,
respectively.
A number of schools are located in the general vicinity of the Lowry Site. Eaglecrest
High School and Thunder Ridge Junior High, 2 miles to the southwest, are the closest
schools. Sunrise Elementary School is within approximately 3 miles of the Lowry Site;
other elementary schools are located in a 4- to 5-mile radius.
Overall, based on information provided by the Cherry Creek and the Aurora School
Districts, 11 elementary schools, 4 middle schools, and 2 high schools are located within
a 5-mile radius of the Lowry Site. Combined enrollment in these schools is about 13,824
students. Over the past 5 years, the net enrollment gain has been about 8.9 percent, or
1.8 percent per year.
2.7 Future Land Use and Populations
Located in the southeast quadrant of the Denver Metropolitan area, the Lowry Site faces
development pressure influenced by the economic growth of the City of Aurora and sur-
rounding area. The City of Aurora anticipates mixed land use for the area surrounding
DEN I 0015399.WP5
2-4
-------
the Lowry Site, as depicted in Figure 2-4. Mixed use includes industrial, commercial,
and residential development compatible with anticipated growth in the area.
The area directly south and west of the Lowry Site, as well as a mile to the north and
northwest, is zoned for office and industrial use. Under the terms of an ordinance issued
by the City of Aurora, new residences may be built as close as 0.5 mile to the south and
west of the Lowry Site, as shown in Figure 2-4. More residences may be constructed
1.5 miles directly north and 2 miles northeast. Residences, in addition to business facili-
ties, could also be developed in the mixed-use corridor along the eastern border.
Land use restrictions were imposed on the Lowry Site by former Denver Mayor Federico
Pefia in June, 1991. Executive Order No. 97 restricts use of the land, surface water, and
ground water on the Lowry Site. Specifically, the Executive Order prohibits:
.
Direct use or reuse of the surface water or alluvial ground water or ground
water in the Dawson and Denver aquifers on or underlying either Section 6
or Section 31 that could cause exposure of humans or animals to contami-
nants, provided that this restriction shall not interfere with treatment and
subsequent use or discharge of any such water.
.
Direct use or reuse of ground water in the Arapahoe and Laramie-Fox
Hills aquifers underlying Sections 6 and 31 for domestic, residential, or
municipal water supply purposes.
.
Water production or dewatering wells constructed on Sections 4, 9, and 32
without the express written consent of the Denver Mayor or his designee.
.
Agricultural development, residential development, commercial develop-
ment, day-care centers, preschool, schools, hospitals, nursing homes,
community recreational facilities, senior citizen centers, restaurants, hunt-
ing, or fishing on Sections 6 and 31.
.
Construction of a building or other structure on those portions of Sec-
tions 6 and 31 that have been used as a landf1ll.
2.8 Location in a Floodplain
Murphy Creek, an intermittent stream in a plains environment, flows north immediately
east of the Lowry Site. The lOO-year floodplain along Murphy Creek has been identified
and mapped for the Federal Emergency Management Agency (FEMA).
DENlOO15399.WP5
2-5
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2.9 General Surface Water and
Ground-Water Resources
2.9.1 Surface Water Resources
The Lowry Site is located within the Murphy Creek drainage system, which covers
approximately 7,800 acres. The unnamed creek and its tributaries in Section 6, and
Murphy Creek and its tributaries to the east and north of Section 6 are included in this
system. These streams generally flow north, and flow is ephemeral, usually in response
to storm events or snowmelt.
2.9.2 Ground-Water Resources
Sixty-one ground-water wells located within 2 miles to the west, south, and east of Sec-
tion 6 and within 3 miles to the north of Section 6 were identified in a ground-water well
inventory. Figure 2-5 shows the locations of the ground-water supply wells in the vici-
nity of the Lowry Site. Table 2-4 summarizes the number and uses of wells within the
well survey area, including wells that are no longer in use.
Although the main source of drinking water for the Denver metropolitan area comes as
surface water from mountain areas, a portion of the metropolitan area's drinking water
needs are met by ground water. The Arapahoe Aquifer yields the largest amount of
ground water and is a source of drinking water for many households in the metropolitan
area. The upper two aquifers, the Denver and the Dawson, serve residents near the
Lowry Site. The Laramie-Fox Hills aquifer is also used in the Denver area. Figure 2-6
is a cross-section of the Denver Basin showing the formations or aquifers beneath the
Lowry Site.
2.9.2.1 Residential Wells
Generally, residential wells in the area are used for potable water and livestock purposes.
Private wells are located in the northeast corner of Section 11, approximately 2 miles
north (downgradient) of the Lowry Site. Four of the residential wells that are closest to
the Lowry Site were sampled by EPA in 1986. No organics were detected, and all sam-
ples were below maximum contaminant levels (MCLs) for inorganics.
2.9.2.2 Industrial Wells
Onsite workers previously used water for industrial and sanitation purposes from a
925-foot deep well located north of the Lowry Site in Section 31 and screened in the
Arapahoe Aquifer. This well was recently abandoned and is no longer in use. A new
well in Section 6 (No. 43 on Figure 2-5) has been drilled and is used for industrial and
sanitation purposes. This new well was screened at a depth of 1,061 to 1,263 feet in the
Arapahoe Aquifer. Although no contaminants have been detected in these wells, com-
mercially bottled drinking water is supplied to workers.
DENlOOI5399.WP5
2-6
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On site workers also used water for industrial and sanitation uses from a well designated
by Denver as B-225 and referred to by the United States Geological Survey (USGS) as
6RDC. The water was not used for human consumption. The well was installed in the
southern portion of Section 6 in 1974 and is reportedly 150 feet deep. The exact loca-
tion, how long the well was in operation, and when and if it was abandoned are
unknown. This well may serve as a conduit for contaminant migration to the deeper
aquifers and is currently buried by approximately 100 feet of refuse.
It should be noted that in addition to well B-225, seven USGS wells were drilled as part
of a study conducted in mid to late 1970 to monitor for water quality and evaluate local
hydrological conditions. These wells were reportedly abandoned, however it is not possi-
ble to confum the abandonment because several of the wells have since been buried under
approximately 100 feet of municipal refuse.
2.9.2.3 Municipal Wells
The East Cherry Creek Valley Water & Sanitation District (ECCV) owns ground-water
rights in the vicinity of the Lowry Site. The ECCV serves unincorporated areas to the
west and southwest of Section 6, using a series of deep ground-water wells to supply
water for domestic uses. The ECCV regularly samples and tests these wells to measure
compliance with requirements of the Safe Drinking Water Act (SDW A). Analytes tested
under the SDW A include inorganics, organics, and primary anions and cations. Addi-
tionally, the ECCV also tests these samples for radionuclides.
City of Aurora residents are served by the municipal water system, which diverts water
from surface reservoirs.
Figure 2-7 shows the drinking water supply sources in the vicinity of the Lowry Site,
including the approximate locations of residential homes with private water wells, areas
serviced by the ECCV, and nonresidential structures with private water wells.
2.10 Surface and Subsurface Features
Site surface features identified and described on Figure 2-8 include structures, roads,
fence boundaries, pipelines and utility lines, surface disposal areas, soil borrow areas,
and other notable surface features.
2.10.1 Structures
Facilities within the northwest quarter of Section 6 are the WMC entrance road and gate,
the WMC scale house, and the WMC maintenance facility, which is surrounded by a
maintenance yard adjacent to the entrance road. Denver's existing ground-water treat-
ment plant and ground-water barrier wall are located approximately 0.5 mile east of Gun
Club Road and 300 feet north of Section 6.
DENlOOlS399.WPS
2-7
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The Command Post is located in the southeast portion of Section 31 in the southeast
corner of the section. The Command Post is the area where drummed wastes from site
investigations are stored and managed, and where trailers are located for the workers.
The Command Post contains a fenced drum storage facility, a decontamination pad, an
office trailer, a storage trailer, and a rock (or drill) core storage shed.
2.10.2 Roads
A paved road extends east from the main entrance along the north section line in Sec-
tion 6 and into Section 31 to Denver's existing ground-water treatment plant.
2.10.3 Fencing
The landfill area within Sections 6 and 31 is enclosed by fences. The north and east
boundaries of the landfIll in Section 31 and the east landfIll boundary in Section 6 are
enclosed by a 4-foot-high barbed-wire fence. The south and west boundaries of the
landfill in Section 6 and the west boundary of Section 31 are enclosed by a 6-foot-high
chain-link fence with a 2-foot-high barbed-wire top.
2.10.4 Pipelines and Utility Lines
Pipelines and utility lines exist primarily around the perimeter of the Lowry Site, as
shown on Figure 2-8. An underground natural gas pipeline and associated surface vents
and access roads trend north-south adjacent to a drainage ditch along the east boundary of
the Lowry Site.
2.10.5 Surface Disposal Areas
Currently, active municipal refuse disposal is occurring in the Phase I area of the new
landfill in the southwest portion of Section 31 (shown as current landf1lling area). The
active landfilling area changes as operations progress. An asbestos disposal area is
currently located in the northwest portion of Section 6, just southwest of WMC's
maintenance facility.
A closed asbestos disposal pit is located in the southeast portion of Section 6. The inac-
tive pit was excavated in the mid 1980s and was approximately 30 feet deep, 100 feet
wide, and 1,000 feet long. Asbestos was double bagged and containerized in drums that
were covered daily with soil. The pit is currently covered by approximately 60 feet of
municipal refuse.
Previous waste disposal practice on the surface of Section 6 consisted of sewage sludge
land application and leachate injection (northern part), leachate spraying (north-central
part), sewage sludge land application (east-central margin), and oil sludge land applica-
tion (southeast margin).
DENlOOI5399.WP5
2-8
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The tire piles that covered a large area in the center of Section 6 (approximately
45 acres) were shredded by an on site tire shredding facility which was operated by
WMC. The shredding project began in October 1989 and was completed by April 1992.
The tire shreds have been placed in a monofilliocated on the east side of the landfill in
east-central Section 6.
2.10.6 Soil Borrow Areas
The soil borrow area currently being used in Section 6 is located south-southeast of
WMC's maintenance facility (Figure 2-8). This area consists of approximately 30 acres.
All surficial soils in this area have been removed to a depth of approximately 15 feet.
Analysis of surficial soil samples taken from this area indicated that levels of
contaminants in the soils were comparable to background levels. EP A, in consultation
with CDH, has approved use of the soils as a daily and final cover for the former landfill
area. They are currently being used as daily cover for landfilling operations in
Section 31.
2.10.7 Surface Drainage and Sediments
EP A has divided surface drainage within the Lowry Site into six subbasins. The drainage
patterns are described in detail in the ODs 4&5 RI report.
2.10.8 Subsurface Features
The Lowry Site is located in the Denver Basin, a north-south trending structural depres-
sion that extends from Pueblo, Colorado, into Wyoming. The basin is asymmetric with a
gently dipping eastern flank bounded by the Great Plains and a very steep to overturned
western flank bounded by the Colorado Front Range. Five major bedrock formations are
regionally important as aquifers in the basin. In descending stratigraphic order, these
formations include the Dawson, Denver, Arapahoe, Laramie, and Fox Hills Formations.
Borings and wells drilled at the Lowry Site penetrate the Dawson, Denver, and Arapahoe
Formations.
A detailed description of the geology/hydrogeology is presented in the Final Rl Report for
OUs 1&6. The following are key features of the surficial deposits and Dawson and
Denver Formations:
.
Surficial sediments that overlie the Dawson Formation. These sedi-
ments consist of residual soil, colluvium, and alluvium. Residual soil is
produced by the in-place weathering of bedrock and colluvium. These
sediments are unconsolidated; poorly to moderately well sorted clays, silts,
sands; and some gravels that are Pleistocene to Holocene in age. The
alluvial deposits are estimated to be about 20 feet wide along the unnamed
creek and occur at depths of 5 to 18 feet.
I>El\IlOOlS399.VVPS
2-9
-------
.
The Dawson Formation unconformably overlies the Denver Formation
an.d is the uppermost bedrock of the basin. The Dawson Formation gene-
rally consists of 800 to 1,000 feet of arkosic conglomerates and sandstones
interbedded with lesser amounts of siltstones, shales, and locallignitic coal
beds. The sandstones are poorly cemented at the Lowry Site. The upper
portion of the Dawson Formation has been eroded, leaving the lower por-
tion of the Dawson exposed. Approximately 200 to 300 feet of the Lower
Dawson is present. The base of the Dawson Formation is generally con-
sidered to be the top of the first thick lignite bed; the formation occurs
approximately 310 feet below ground surface in the southern portion of
Section 6, and approximately 180 feet below ground surface in the central
portion of Section 31.
.
The Denver Formation is of late Cretaceous and Paleocene age and
unconformably underlies the Dawson Formation. The Denver Formation
consists of approximately 600 to 1,500 feet of interbedded claystones,
siltstones, fine-grained sandstones, minor conglomerates, and lignites. The
sandstone units are lenticular and discontinuous. The formation contains
an overall greater proportion of fine-grained sediments than either the
Arapahoe or the Dawson Formation.
.
The Arapahoe Formation, of late Cretaceous age, is a 400- to 700-foot-
thick sequence of interbedded conglomerates, sandstones, siltstones, and
shales that unconformably overlies the Laramie Formation. The Arapahoe
Formation is distinguished from the underlying Laramie Formation and
overlying Denver Formation by (1) the larger proportion of conglomerates
and sandstones with respect to shales, (2) the absence of significant carbo-
naceous beds, and (3) a generally lighter color. The Arapahoe Formation
contains a greater proportion of coarser-grained sediments and generally
lacks the coal beds found in the overlying Denver Formation. Coarser
sandstones and conglomerates characterize the lower 100 to 200 feet of the
formation, and the upper portion is generally finer grained and darker in
color. Limited information is available on the onsite Arapahoe Formation.
Well WW40, recently installed by WMC as a water supply, provides the
only onsite data regarding the Arapahoe Formation. This well encountered
the top of the formation at 1,004 feet below ground surface.
2.10.8.1 Hydrogeologic Conceptual Model
Available ground-water data from the Lowry Site monitoring programs were reviewed to
develop a hydrogeologic conceptual model that is described in the Final Rl Report for
OUs 1&6. The hydrogeologic conceptual model divides the water-bearing units beneath
the Lowry Site into a shallow and a deep ground-water system. The division is based on
the presence of a separation layer within the lower part of the Lower Dawson Formation.
The shallow ground-water system (OU 1) includes all ground water contained within the
DENlOOlS399.WPS
2-10
-------
alluvium and within the Dawson Fonnation above and including the separation layer.
The deep ground-water system (OU 6) consists of all ground water below the separation
layer. Figure 2-10 presents a schematic drawing of the conceptual model that depicts the
Dawson and Denver Aquifers.
2.10.8.2 OU 1: Shallow Ground-Water System
Ground-water flow in the shallow ground-water system occurs within the weathered and
unweathered Dawson Fonnation, the overlying alluvial deposits, the refuse, and waste-pit
solids.
Predominant ground-water flow direction in the unweathered Dawson is toward the north
with an estimated mean velocity of 0.03 ft/year. There are also components of flow to
the east and west. Recent compliance boundary sampling has detected contaminants in
Well U-510. This well is located on the. southern border of the Lowry Site and was
previously considered to be an upgradient well. Sampling results from this well confirm
that contamination has migrated to the south of the waste pit source area.
Additional monitoring wells were installed in Section 7 to evaluate ground-water contami-
nation and flow. Preliminary data show an eastern component of ground-water flow in
the weathered Dawson. These data will be incorporated with site data to further refIne
interpretations of ground-water flow south of the Lowry Site.
2.10.8.3 OU 6: Deep Ground-Water System
Deep ground water is defIned as the water-bearing zones below the Dawson Aquifer.
These strata include the lower portion of the Dawson Fonnation beneath the Lowry Site
and the underlying fonnations extending vertically through the Arapahoe Aquifer to the
base of the Laramie-Fox Hills Aquifer. Ground-water flow within the deep ground-water
system is predominantly lateral and to the north.
The Denver Aquifer extends from the base of the separation layer to the top of the
Arapahoe Aquifer. A laterally continuous lignite bed extends across the Lowry Site and
stratigraphically divides the Denver Aquifer into upper and lower zones.
The Arapahoe Aquifer beneath the Lowry Site extends from the base of the Denver
Aquifer to the top of the Laramie-Fox Hills Aquifer.
DENIOO I S399.WPS
2-11
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DEN Graphllowry ROD/100
2-12
Figure 2-1
THE LOWRY SITE AND
DADS FACILITY LOCATION
LOWRY RECORD OF DECISION
~ DADS
-------
A-1
A-1
Zoning Legend
A-1: Agricultural Usage with One Farm Unit
COvering at Least 20 Acres
RIA: ResidentiaVAgricultural Usage with One
Single Family Domestic Unit per 2.5 Acres
PCZD: Planned Community Zone District
o
,
1/2
M-1:
N:
Light Industrial District
No Use Status - Not Zoned Yet
Highway Service District
Scale in Miles
The locations shown are approximate.
RIE: ResidentiaVEstates Usage with One Single
Family Domestic Unit per 1.7 Acres
83: Community Business/Genera! Retail
UU: Mixed Use
B-3:
8-4:
Business and Community District
Planned Development Zone District
Heavy Industrial District
PD:
M-3:
R-1: Single Family Residential District - Low
Density (5.2 Dwelling UnitsfAcre)
R-2: Medium Density Multi-Family Residential
District Medium Density (14.5 Dwelling UnitsfAcre)
lIE]
F:
City 01 Aurora
Flood Zone
Figure 2-2
CURRENT ZONING IN
THE VICINITY OF THE
LOWRY SITE
LOWRY RECORD OF DECISION
DEN GraptVLowry ROD/101
2-13
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The locations shown are approximate.
Scale in M~es
DEN GraphlLowry ROD/102
Figure 2-3
MAJOR LAND USES IN THE
VICINITY OF THE LOWRY SITE
LOWRY RECORD OF DECISION
2-14
-------
SFD
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Scale in Miles
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-
Proposed E-470 Alignment
Figure 2-4
EXPECTED FUTURE LAND USE IN
THE VICINITY OF THE
LOWRY SITE
LOWRY RECORD OF DECISION
DEN Graphllowry ROD/103
2-15
-------
Legend
7 Section Number
3~ Well Identification Number (Well locations are approximate).
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Scale in Feet
The locations shown
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2-16
Figure 2-5
GROUND-WATER
SUPPLY WELLS
LOWRY RECORD OF DECISION
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LEGEND:
Dawson Formation
Denver Formation
Arapahoe Formation
Laramie Formation
Fox Hills Sandstone
West LOWRY East
LANDFILL Dawson Arkose
7000 7000
6000 6000
(j) 5000
Q) 5000
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4000 4000
Pierre Shale
3000 3000
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8000
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7000
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The locations shown are approximate.
DEN GraphILowry ROD/140
Figure 2-6
CROSS-SECTION THROUGH
THE DENVER BASIN
LOWRY RECORD OF DECISION
8000
7000
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- East Cherry Creek Valley Water & Sanitation District Service Area
A-5 Active Municipal Well Completed in Arapahoe Aquifer
L-5 Active Municipal Well Completed in Laramie Aquifer
Note: Water wells, homes and facility locations are approximate.
DEN Graph/Lowry ROD/143 2-18
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DRINKING WATER
SUPPLY SOURCES
LOWRY RECORD OF DECISION
-------
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Scalehouse
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Section 31
-'"''
CURRENT LANDFILLING AREA
EAST
HAMPDEN
AVENUE
Gate
Buried
~o
HigI Vdtage
Powerine
Inactive
Asbestos
Disposal
Pit
N
!
Notto Scale
LEGEND:
Landfill Boundary (Fence Line)
Fonner Landfill Boundary
The locations shown are approximate.
DEN GraptVLcwry ROD/166
2-19
Figure 2-8
LOWRY LANDFILL SITE SURFACE
FEATURES
LOWRY RECORD OF DECISION
-------
5860
5840
5820
5800
5780
5760
5740
Iii 5720
w
L1.
~ 5700
z
0
~ 5680
>
~ 5660
w
5640
N 5620
I
N
0 5600
5580
5560
5540
5520
5500
Shallow Ground-Water System
and Subsurface Liquids
Operable Unit No.1
Deep Ground-Water System
Operable Unit No.6
':L
o 500'
Vertical Exaggeration = 10x
Base of W
ealhered Da
wson Form "
Unweathered Dawson a Ion
Formation/Dawson Aquifer
Separation Layer
Lower Dawson Formation/Denver Aquifer
~'"'te
,
The locations shown are approximate,
DEN Graph/Lowry ROD/129
~
Upper Denver Formation
E
CD
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c:
CD
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5840
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5580
5560
5540
5520
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Figure 2-9
SCHEMATIC OF HYDROGEOLOGIC SETTING
LOWRY RECORD OF DECISION
-------
N
~
......
Table 2-1
Wildlife Species Observed Within or Near the Lowry Site
Mammals Birds Reptiles
Black-tailed Prairie Dog Ring-necked Pheasant Plains Garter Snake
(Cynomys ludovicianus) (Phasianus colchicus) (1hamnophis radix)
White-tailed Jackrabbit Mallard (Anas platyrhynchos) Gopher Snake
(Lepus townsedii) (Pituophis melanoleucus)
Coyote (Canis latrans) Green-winged Teal (Anas crecca) Short-horned lizard
(Phrynosoma douglasSI)
Pronghorn American Wigeon Prairie Rattlesnakes
(Antilocapra americana) (Anas Americana) (Crotalus viridis viridis)
Mule Deer (Odocoileus hemionus) Red-tailed Hawk (Buteo janaicensis)
White-tailed Deer Common Snipe (Capella gallinago)
(Odocoileus virginianus)
Great Horned Owl (Bubo virgonianus)
Black-billed Magpie
(Eremophila alpestris)
American Robin (Turdus migratorius)
Western Meadowlark
(Sturnella neglecta)
Starling (Sturn us vulgaris)
Vesper Sparrow (Poocetus gramineus)
Mourning Dove (Zenaida macrowa)
DENlOO15271.WP5/3
-------
IV
N
IV
Table 2-2
Plant Species Noted Within the Vicinity of the Lowry Site
Page 1 of 2
Grasses Riparian Wetlands Wet/Meadows
Needle-and- Thread Plains Cottonwood Sedges (Carex spp.) Mallow (Malva sp.)
(Stipa comata) (Populus sargentii)
Sand Grama Peach leaf Willow American Bulrush Western Ragweed
(Sporobolus cryptandrus) (Salix amygdaloides) (Scirpus americanus) (Ambrosia psilostachya)
Blue Grama Skunkbush Water Speedwell Fleabane (Erigeron sp.)
(Boute/oua gracilis) (Rhus trilobata) (Veronica anagallis-aqootica)
Buffalo Grass Alkal Muhly False Gromwell
(Buchloe dactyloides) (Muhlenbergia asperifolia) (Onosmadium moUe)
Sagebrush Common Spike-rush Curly Dock
(Artemisia frigida) (Eleocharis machrostachya) (Rumex crispus)
Common Rabbit Brush Licorice Cockel-lour
(Chysothamnus nauseosus) (Glycrrhiza lepidota) (Xanthium italicum)
Western Wheat Grass Broad-leaved Cattail Purple-flowered Ground
(Agropyron smith;;) (Typha latifolia) Cherry (Physalis lobata)
Bromes (Bromus spp.) Sandbar Willow
(Salix exigoo)
Three-awn Canadian Thistle
(Aristida longiseta) (Cirsium arvense)
Cushion Coryphanta Evening Primrose
(Coryphanta vivipara) (Oenothera strigosa)
Yucca (Yucca sp.) Horseweed
(Conyza canadensis)
Bull-thistle Foxtail Barley
(Cirsium vulgare) (Hordeum jubatum)
DEN1OO15271.WP5/1
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Table 2-2
Plant Species Noted Within the Vicinity of the Lowry Site
Page 2 of 2
Grasses Riparian Wetlands Wet/Meadows
Red Globe Mallow
(Sphaeralcea coceinea)
Blazing Star
(Liatris punetata)
Prairie Coneflower
(Ratibida colonmifera)
Scurfpea
(Psoralea tenuijlora)
N
I
N
\j.)
DENI0015271.WP5/2
-------
Table 2-3
. Potentially Occurring Threatened and Endangered
Species Within or Around the Lowry Site
Birds
Peregrine falcon Falco peregrinus
Bald Eagle Haliaeetus leucocephalus
Black tern. Chlidonia niger
Mountain plover- Charadrius montanus
White-faced ibis. Plegadis chihi
Baird's sparrow Ammodramus bairdii
Amphibians
Western boreal toad. Bufo boreas boreas
Insects
Regal fritillary butterflY- Speyeria idalia
Mammals
Preble's meadow jumping mouse Zapus hudsonius preblei
Swift fox. Vulpes velos
.Species that are candidates for official listing as threatened or
endangered species (Federal Register, Vol. 54, No.4, January 6,
1989; Vol 55, No. 35, February 21, 1990).
DENIOOIS272.WPS
2-24
-------
Table 2-4
Well Inventory Sllmm;lry Page 1 of 2
Well Aquifer
Use Numbers Designation Comments
Domestic/Livestock 5, 8, 10, 14, Denver, Some wells may be used for
15, 16, 18, Dawson, or only part of the year. Well
19, 21, 22, unknown Nos. 22 and 50 are not
25, 28, 31, currently used but future use
44, 45, 49, is possible. Use of Well
50, 51, 52, No. 59 is unknown but is
53, 54, 56, listed as domestic.
57, 58, 59,
60, 61
Windmill 4, 6, 7, 23, Denver, Primarily used for livestock.
42 Dawson, or
unknown
Industrial 1, 24 Denver Well No. 24 is closed.
Industrial 43 Arapahoe Well No. 43 replaced Well
No. 24.
Municipal 29, 32, 36 Arapahoe Owned by East Cherry
Creek Valley Water and
Sanitation District.
Municipal 33,37 Laramie-Fox Owned by East Cherry
Hills Creek Valley Water and
Sanitation District.
Municipal 34 Denver Owned by East Cherry
Creek Valley Water and
Sanitation District; however,
the well is currently not
used.
Municipal 35 Denver/Dawson Owned by East Cherry
Creek Valley Water and
Sanitation District; however,
the well is currently not
used.
Unknown 2, 26, 27, 30, Denver, Locations not verified.
38, 39, 40, Dawson, or
41, 55, unknown
3 unnumbered
wells
DENlOO15272.WPS
2-25
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I Table 2-4 Page 2 of 21
Well Inventory Summary
Well Aquifer
Use Numbers Designation Comments
Municipal permit NA Arapahoe Permit application by East
pending Cherry Creek Valley Water
and Sanitation District.
Municipal permit NA Laramie-Fox Permit application by East
pending Hills Cherry Creek Valley Water
and Sanitation District.
Not currently in use 3, 9, 11, 12, Denver, Well Nos. 46 and 47 are
13, 17, 20, Dawson, or located on property that is in
46, 47, 48 Arapahoe bankruptcy proceedings.
Well No. 48 is located in a
recreational area that is no
longer used.
I Notes: NA = Not applicable. I
DENlOO15272.WP5
2-26
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Section 3.0
Site History and Enforcement Activities
-------
Section 3.0
Site History and Enforcement Activities
3.1 Operational History
In the late 1930s, Denver purchased land southeast of its corporate limits for the purpose
of attracting an Anny Air Corps Technical School to Denver. In December 1937, the
Denver City Council conveyed title of the land, without cost, to the Federal government.
From about 1940 to 1962, the U.S. Air Force used the Lowry Site as a bombing range.
In 1962, Denver became aware that the Bombing Range (with certain exceptions for
missile launching complexes) had been declared a surplus property by the Federal govern-
ment. In 1964, the United States conveyed all or portions of the five sections of the
Lowry Bombing Range back to Denver by Quitclaim Deed, with the provision that the
land be used for public utility purposes; specifically, a landfill.
In February 1966, Denver began operation of a municipal solid waste landfill. Liquid
and solid municipal refuse and industrial wastes, including sewage sludge, were accepted
until 1980. These materials included hazardous substances, such as volatile organic
compounds and heavy metals, listed pursuant to 40 CFR Section 302.4.
From 1966 until 1980, approximately 138 million gallons of waste were disposed of at
the Lowry Site, primarily by using a disposal practice known as "co-disposal." Approxi-
mately 75 unlined waste pits or trenches were excavated to accommodate a mixture of
liquids, industrial waste, and municipal waste. In the southern half of Section 6, the pits
were filled about three-quarters full with liquid wastes and topped with 25 to 60 feet of
municipal refuse. The waste pits ranged in depth from approximately 15 to 30 feet,
length from 100 to 1,100 feet, and width from 50 to 150 feet. No measures are known
to have been implemented to prevent leachate or liquid waste seepage from the pits.
Consequently, over time, the liquid seeped out of the pits and mixed with the surrounding
refuse and ground water. In the north-central portion of Section 6, excavated pits were
filled with liquid wastes and municipal refuse, then covered with 2 to 5 feet of native soil
and piles of discarded tires. Over time, this liquid seeped out to ground water and to
surface water in unnamed creek. Approximately 8 million tires were stockpiled at the
Lowry Site in the 1970s.
In addition, land application of wastewater sludge began at the Lowry Site in 1969 and
continued into 1986. Approximately 160 acres along the northern and eastern boundaries
of Section 6 were utilized for land application of wastewater sludge. The wastewater
sludge was applied to the surface and then incorporated into the native soils. After 1980,
leachate collected in on site surface impoundments was injected in the same 160-acre area.
Figure 3-1 presents the waste pits, tires, and sludge application areas.
DENlOO1539C.WP5
3-1
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The -total volume of liquid wastes disposed of at the landfill is estimated to be
138 million gallons. This estimate was developed from the records kept by the landfill
and by the parties disposing of the wastes. The types of wastes disposed of at the Lowry
Site until 1980 include acid and alkaline sludges; asbestos; caustic liquids and solids;
brines, including plating wastes and other water-based sludges; laboratory wastes;
organics, including petroleum based oils, grease, chlorinated solvents, and sludges; waste
solvents, chemicals, and oil; biomedical wastes; low-level radioactive medical wastes;
pesticides and garden chemicals; water-soluble oils; sewage sludge; paint and varnish
waste, sludge and thinners; photographic chemicals and industrial solvents; construction
waste; municipal refuse; household hazardous waste; appliances; tires; livestock car-
casses; and metallic wastes.
Waste Management of Colorado, Inc. (WMC), operator of the landfill and a subsidiary of
Waste Management of North America, Inc., began landfill operations on July 30, 1980,
under a contract with Denver. At that time, waste disposal in Section 6 was restricted to
municipal refuse and at a later time, asbestos waste.
Municipal solid waste (MSW) disposal activities at the Section 6 (Figure 3-1) landfill unit
ceased in August of 1990. A minimum 4-foot thick soil cover (except for the north
slope) was completed over the landfill unit, which is now closed. One area of Section 6
west of the landfill continues to receive asbestos wastes, which is disposed of in sealed
containers. Asbestos disposal is regulated by the Colorado Department of Health (CDH).
In addition, Section 6 also contains 7.5 million shredded tires in a monofill to the north
of the landfill on the east side of the section, and construction wastes from the Surface
Water Removal Action (SWRA) were disposed immediately north of the landfill.
Section 31, located north of the Lowry Site, is currently being used for disposal of
MSW.
3.2 History of Site Investigations
3.2.1 Site Investigation Activities from 1964 to 1984
Preliminary site investigations at the Lowry Site began in the mid-1970s. Various parties
including United States Geological Survey (USGS), EPA, CDH, Denver, and WMC
performed site studies before 1984 when the Lowry Site was named a Superfund site
through listing on the NPL. These investigations included installation of ground-water
monitoring wells, surface-water and sediment sampling, air studies, soil gas monitoring,
and surface geophysical surveys.
DENIOO1539C.WPS
3-2
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3.2.2 Preliminary Assessment, Hazard Ranking, and NPL Listing
A preliminary assessment (PA) was conducted of the Lowry Site in June 1982 and a site
inspection (S1) was conducted in August 1982. The PAISI briefly identified contaminant
sources, pathways, receptors, and the existing use of the Lowry Site's surrounding envir-
onment. The results of the P AISI were used to apply the Hazard Ranking System (HRS)
to the Lowry Site. The HRS results in a cumulative score based on ground-water, sur-
face-water, and air risks. EPA has determined that a score of 28.5 or higher on the HRS
is required for a site to be eligible for the NPL. In August 1982, the Lowry Site was
given an HRS score of 21. In March 1983, the Lowry Site was reevaluated and assigned
a score of 49.35. After a quality analysis (QA) check, the score was revised to 48.36.
The Lowry Site was added to the NPL on September 21, 1984.
3.2.3 Phase I RI: February 1985 to April 1986
The first phase of the RI was conducted by EP A and included data collection and anal-
yses of site conditions to evaluate onsite and offsite geologic conditions, types and
concentrations of contaminants in all media, locations of buried waste pits, preliminary
characterization of site contaminants, and climatological conditions.
The field investigations conducted include geophysical investigations, soil vapor studies,
installation of monitoring wells, air monitoring and operation of an onsite meteorological
station, and ground-water, surface-water, soil, sediment, landfill solids, and landfIll gas
sampling.
The findings of these investigations are described in the Phase I RI report, dated
September 1986.
3.2.4 ATSDR Determination
In January 1987, the Agency for Toxic Substances and Disease Registry (A TSDR)
conducted an assessment of the public health threat attributed to ground-water
contamination and volatile organic compounds (VOCs) being released from the soil. The
1987 health assessment concluded that the Lowry Site was a potential public health
hazard.
3.2.5 Phase n RI: January 1987 to October 1989
The second phase of the RI was conducted by EP A and involved remedial planning,
preliminary assessment of data and risks, and an extensive sampling program. The inves-
tigations included installation of exploratory borings, well points, deep and shallow
ground-water wells, and refuse leachate wells; ground-water, refuse, surface-water,
waste-pit liquid, soil, and landfill solids sampling; water and liquid level monitoring;
limited air monitoring; and continued collection of meteorological data.
DEN 1001 S39C.WP5
3-3
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EPA issued a series of technical memoranda that constituted Phase n of the RI.
3.3 ffistory of CERCLA Enforcement
In 1988, EPA divided the Lowry Site into six OUs, or study areas. These were grouped
according to the contaminated media which they address: OUs 1&6 address shallow
ground water, subsurface liquids, and deep ground water; OUs 2&3 address landfill
solids and landfill gas; and OUs 4&5 address soils, surface water, and sediments. A
complete description of each operable unit may be found in the Glossary of this ROD.
In accordance with the requirements of CERCLA, as amended by SARA, EP A provided
the potentially responsible parties (PRPs) with the opportunity to perform the au RI/FSs
at the Lowry Site. Under the terms of negotiated Administrative Orders on Consent
(Consent Orders), groups of PRPs performed the aU-specific RI/FSs. The elements of
each au RIfFS are described in a Conceptual Work Plan (CWP), which is attached as an
Appendix to each Consent Order.
3.3.1 The 1988 Consent Order for OU 1 RIIFS and the 1989 Amended
and Restated Consent Order for OU 6 RIIFS
The purpose of the 1988 Consent Order (Docket No. CERCLA VIII-88-18) for the
Shallow Ground Water and Subsurface Liquids au (aU 1) was to establish requirements
for the au 1 RIfFS to be performed by the Lowry Coalition Respondents. The Lowry
Coalition Respondents included Adolph Coors Company, AMAX Research &
Development, Inc. (formerly known as AMAXfExtractive Research & Development,
Inc.), Asamera Oil (U.S.) Inc., Conoco Inc., Gates Rubber Company, Hewlett Packard
Company, Honeywell Inc., International Business Machines (IBM), City of Lakewood,
Littleton-Englewood Bi-City Wastewater Treatment Plant, Metro Wastewater Reclamation
District (formerly Metropolitan Denver Sewage Disposal District No.1), Sundstrand
Corporation, Syntex Chemicals, Inc., and S.W. Shattuck Chemical Company Inc. The
Consent Order was amended in December 1989 to include the Deep Ground Water au
(aU 6). The amended Consent Order is referred to as the Second Amended and Restated
Consent Order.
The OUs 1&6 RI report was completed in March 1992, and the FS report was completed
in October 1992.
In accordance with the terms of the Consent Order, the Respondents agreed to reimburse
the Superfund for all response costs incurred by EP A not inconsistent with the NCP
related to the Consent Order. For OUs 1 and 6, EPA has billed a total of $2,002,648.05
for cost recovery (including interest and stipulated penalties) and has collected
$1,300,189.58 through September 1993.
DENIOO1539C.WPS
3-4
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3.3.2 The 1990 Administrative Order on Consent for
OUs 2&3 RIIFS
The purpose of the 1990 Consent Order (Docket No. CERCLA VIII-90-1) for the
Landfill Solids (OU 2) and Landfill Gas (OU 3) OUs was to establish requirements for
the OUs 2&3 RIfFS to be performed by Respondents Chemical Waste Management, Inc.
(CWM), Waste Management of Colorado, Inc. (WMC), and Denver. The Consent Order
for these OUs was signed in January 1990.
The RI report was issued on January 7, 1993, and amended by EPA's comments (May 6,
1993). The FS report was issued on April 8, 1993, and amended by EPA's comments
dated May 6, 1993.
Under the terms of the Consent Order, the Respondents agreed to reimburse the United
States for all response costs incurred by the United States that are not inconsistent with
the NCP related to the Consent Order. Because of the special circumstances of the City
and County of Denver's municipal financing restrictions, the Respondents were granted
the option of partially reimbursing the United States for each billing until the final
accounting was submitted. Upon receipt of the final accounting, Respondents are to
reimburse the United States for all response costs, including those costs not previously
reimbursed and the associated accrued interest on those costs not previously reimbursed.
In accordance with the partial payment provisions, EPA has billed $1,463,016.09 and
collected $249,719.50 through September 1993.
3.3.3 The 1991 Consent Order for OUs 4&5 RIIFS
The purpose of the 1991 Consent Order (Docket No. CERCLA vm-91-04) for the Soils
(OU 4) and Surface Water and Sediments (OU 5) OUs was to establish requirements for
the OUs 4&5 RIfFS to be performed by Respondents Metro Wastewater Reclamation Dis-
trict (Metro) and Denver. The Consent Order for these OU s was signed in March 1991.
The RI report was issued on January 20, 1993, and amended by EPA's comments dated
February 17, 1993. The FS report was issued on April 16, 1993, and amended by
EPA's comments dated May 18, 1993.
Under the terms of the Consent Order, the Respondents agreed to reimburse the United
States for all response costs incurred by the United States not inconsistent with the NCP
related to the Consent Order. Because of the special circumstances of the City and
County of Denver's municipal financing restrictions, the Respondents were granted the
option of partially reimbursing the United States for each billing until the final accounting
was submitted. Upon receipt of the final accounting, Respondents are to reimburse the
United States for all response costs, including those costs not previously reimbursed and
the associated accrued interest on those costs not previously reimbursed. In accordance
DENlOOlS39C.WP5
3-5
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with the partial payment provisions, EP A has billed $486,331.50 and collected
$75,376.63 through September 1993.
3.3.4
ffistory of the 1984 Barrier Wall Consent Order, the 1986 Barrier
Wall Consent Decree, the 1991 Surface Water Removal Action,
and the 1993 Modified Consent Decree
In 1984, Respondent Denver entered into a Consent Order with EPA, for the design,
construction and operation of an interim remedial measure (IRM). This IRM consisted of
a ground-water control and treatment system, commonly referred to as the barrier wall
and ground-water treatment plant. The ground-water barrier wall was designed to mini-
mize the offsite migration of contaminated shallow ground water by collecting the
contaminated ground water at the barrier wall and pumping it to the ground-water
treatment plant.
In 1985, EP A alleged that Denver failed to fulfill certain conditions of the Consent Order
and to resolve these alleged violations, entered into a Consent Decree with Denver in
January 1986. In June 1986, EPA, CDH, and Denver began discussions regarding
implementation of the SWRA. The SWRA would be designed to enhance the existing
measures that prevent offsite migration of contaminants from the Lowry Site. In pursuit
of this goal, EPA issued an Engineering Evaluation/Cost Analysis (EE/CA) on May 19,
1988, which described and evaluated alternatives for the SWRA.
On October 25, 1990, EPA issued a Responsiveness Summary to provide a written
response to the public comments received on the EE/CA for the SWRA. EPA developed
and issued an Action Recommendation on November 13, 1990, which defines the basis
and scope of the SWRA. The requirements for the SWRA replaced those that had been
identified in the 1984 Consent Order and 1986 Consent Decree. The SWRA Consent
Order became effective on August 15, 1991.
Final design plans for upgrading the ground-water treatment plant and construction of a
collection system within unnamed creek were completed in June of 1992. Construction
of both the treatment plant additions and collection system was completed in November
of 1992. The upgraded treatment plant is referred to as the existing ground-water treat-
ment plant.
Under the terms of the Consent Order, the Respondents agreed to reimburse the United
States for all response costs incurred by the United States not inconsistent with the NCP
related to this Consent Order. The Consent Order for the Surface Water Removal Action
was attached to the Modified Consent Decree. By attaching the SWRA Consent Order to
the Modified Consent Decree, updated performance standards and compliance monitoring
requirements, specified for the SWRA, replaced those identified in the 1984 Consent
Order and 1986 Consent Decree. Although the SWRA Consent Order became effective
on August 15, 1991, the Barrier Wall Modified Consent Decree was not filed with the
DENlOO1539C.WPS
3-6
-------
U.S. District Court until July 13, 1993. On September 29, 1993, the Barrier Wall
Modified Consent Decree was signed and entered by United States District Court Chief
Judge Sherman Finesilver.
Because of the special circumstances of the Denver's municipal financing restrictions, the
Respondents were granted the option of partially reimbursing the United States for each
billing until the final accounting was submitted. Upon receipt of the final accounting,
Respondents are to reimburse the United States for all response costs, including those
costs not previously reimbursed and the associated accrued interest on those costs not
previously reimbursed. In accordance with the partial payment provisions, EP A has
billed $443,279.76 and collected $56,924.70 through September 1993.
3.3.5 ffistory of the 1989 Drum Removal Action
During a routine inspection of the drum storage area on February 9, 1989, EPA observed
that many of the drums were damaged. EP A initiated a drum removal action on
March 1, 1989, to allow EPA's Emergency Response Branch to stabilize the drums and
control the liquids. In conjunction with this removal action, EP A constructed two tem-
porary lined storage pads to contain the drums and to manage the liquids.
In 1990, EPA conducted Phase n of the Drum Removal Action in cooperation with
Denver. This removal action involved: bulking the less contaminated wastes and treat-
ing them in the ground-water treatment plant; re-packaging the highly contaminated
liquids and solids from the old drums; decontaminating and disposing the empty drums;
and decommissioning the temporary drum storage pad.
3.3.6 PRP Search
In accordance with Section 104(e) of CERCLA, as amended by SARA, EPA conducted a
search for the parties who generated, treated, stored, or disposed of materials at the
Lowry Site (including the owners and operators). This included obtaining information
from the parties pertaining to their ability to pay for or perform the cleanup of the Lowry
Site. In conjunction with the identification of PRPs at the Lowry Site, EP A:
.
Issued requests for information from parties who were known to have
involvement with the Lowry Site.
.
Issued General Notice letters in May 1988 to the 195 companies believed
to have generated, treated, stored, or disposed of hazardous waste at the
Lowry Site and the owners and operators of the landfIll.
.
Developed a Waste-In List to determine the volume and composition of
wastes that were generated or transported to the Lowry Site.
DENlOOlS39C.WP5
3-7
-------
.
Issued Special Notices to selected groups of PRPs to perform the OU
RIfFSs. EP A issued the following Special Notice letters to the PRPs at the
Lowry Site:
On June 24, 1988, EPA issued a Special Notice to 28 PRPs to
perform the OU 1 RIfFS. The majority of these PRPs joined
together to form a group known as the Lowry Coalition. (This
agreement was later amended in December 1989 to include the
OU 6 RIfFS.)
On June 30, 1989, EPA issued a Special Notice to Denver, WMC,
and CWM to perform the RIfFS for OUs 2&3.
On October 19, 1990, EPA issued a Special Notice to Denver and
Metro to perform the RIfFS for OU s 4&5.
3.3.7 Bankruptcy Settlements
The United States, on behalf of EPA, entered into bankruptcy settlement with Storage
Technology Corporation (STC) which was consummated in 1993. Under the STC settle-
ment, EPA recovered $3,304,672.89 in past response costs, and $4,957,009.33 in future
response costs incurred at the Lowry Site. In addition, EPA received payment of
$29,133.14 from the bankruptcy trustee for C.W. Silver.
3.3.8 De Minimis Settlements
This subsection discusses the CERCLA Section 122(g) de minimis settlements negotiated
with eligible de minimis parties. To qualify as a de minimis PRP:
.
The party's volumetric contribution must be 300,000 gallons of waste or
less.
.
The party's waste stream must not be significantly more toxic or of greater
hazardous effect than all other waste streams at the Lowry Site.
.
The settlor must have certified that the information provided in its
CERCLA Section 100(e) information request response was accurate and
complete.
.
At the time of the settlement, the settlor must not have been a party to any
other litigation pertaining to the Lowry Site against or challenging the
EPA.
DENlOO1539C.WP5
3-8
-------
In March 1993, EPA entered into a Consent Order (Docket No. CERCLA VIII-93-04)
with 22 of 144 eligible de minimis PRPs. Respondents entering into this de minimis
settlement are listed in Table 3-1. These settlors paid a total of $633,789.81 to the
Superfund Trust Fund.
In October 1993, EPA entered into a Consent Order (Docket No. CERCLA VIII-93-21)
with three Colorado state agencies and two Colorado state colleges. Respondents
entering into this settlement are listed in Table 3-1. These settlors paid a total of
$653,570.97 to the Superfund.
DENlOO1539C.WPS
3-9
-------
Area of Waste Pit Containing Liquids
Boundary of Area of Suspected
Liquid Waste Pits (Source Area)
Landfill Boundary (Fence Line)
Former Landfill Boundary
EAST
HAMPDEN
AVENUE
Active:; :
Asbestos . -.co: '- i
~~spcA :~ --T---"
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LEGEND:
.
----
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lire Pile
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EAST QUINCY AVENUE
The locations shown are approximate.
Section 31
--------.
Tire Shreds
MonofilJ
N
i
Na to Scale
Figure 3-1
APPROXIMATE WASTE PIT,
TIRES, AND SLUDGE APPLICATION AREA
LOCATIONS
LOWRY RECORD OF DECISION
3-10
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Table 3-1
De Minimis Settlement, Consent Order Docket No. CERCLA vm-93-04
Effective August 28, 1992
and De Minimis Settlement Consent Order Docket No. CERCLA vm-93-21
Effective June 2, 1993
Amount
Potentially Responsible Party ($)
Docket No. CERCLA VIll-93-04
Adams Arapahoe Joint District No. 281 $1,085.76
Allied Trades, Inc. (now known as Barnett Lumber Co.) 2,262.00
Asarco Inc. Globe Plant 20,358.00
AT&T Industries, Inc. 5,655.00
Burlington Northern Railroad 2,488.20
Camp Dresser & McKee, Inc. 8,991.45
City of Colorado Springs 1,950.98
Cobe Laboratories, Inc. 79,464.06
Lowenstein Theater/Denver Center for the Performing Arts 28.28
Marathon Oil Company 1,131.00
Martin Marietta Corporation - Denver Aerospace 94,975.73
National Wire and Stamping, Inc. 6,141.33
Pepsi-Cola Bottling Company 15,364.64
Samsonite Corporation 30,508.73
Smith Kline Beecham Corporation 6,220.50
U.S. Geological Survey National Water Quality Laboratory 61,271.93
U.S. Air Force 116,866.23
U.S. Defense Logistics Agency 24,259.95
U. S. EP A Region VIII Lab 1,413.75
U.S. Mint, Treasury Department 42,978.00
U.S. Veterans Administration Medical Center 106,133.04
ValleyLab, Inc. 4,241.25
Subtotal $633,789.81
Docket No. CERCLA VIll-93-21
Colorado Department of Agriculture $7,441.98
Colorado Department of Highways 175,203.21
Colorado School of Mines 46,246.59
Colorado Surplus Agency 369,316.74
Colorado State University (Environmental Health Services) 55,362.45
Subtotal $653,570.97
De Minimis Total $1,287,360.78
DENlOO1539C.WP5
3-11
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Section 4.0
Highlights of Community Participation
-------
Section 4.0
Highlights of Community Participation
EPA implemented a broad-based, comprehensive community involvement program to
keep the community informed about the Lowry Site, and to provide an opportunity for
citizens to participate in the Superfund process.
4.1 Community Relations Plan
A Community Relations Plan for the Lowry Site was first developed in 1984. The Com-
munity Relations Plan provided a basis for EPA's community involvement program at the
Lowry Site by identifying community interests and concerns, and outlining the commun-
ity relations activities to be conducted. In December 1987, EPA conducted interviews
with other agencies, community groups, and individuals as a first step in updating the
Community Relations Plan. A draft of the revised Community Relations Plan was issued
for public comment in March 1988. The plan was revised based on the comments
received and the Revised Community Relations Plan was issued in January 1989.
4.2 Lowry Landfill Monitoring Committee
EPA participated in the Lowry Landfill Monitoring Committee (LLMC), which was
established by the Governor of Colorado. This committee met on a quarterly basis for
several years. EP A provided information to the committee and offered to assist in dis-
tributing information to the public. The purpose of the committee was to provide a
channel of communication among industry representatives, private citizens, and the State
of Colorado. LLMC meetings were discontinued once all participants were satisfied with
the progress at the Lowry Site.
4.3 Technical Advisory Group
In July 1987, EPA organized the Technical Advisory Group (TAG), which was composed
of various regulatory agencies, local governmental entities, PRPs, and community organi-
zations interested in Lowry Site activities. The purpose of the TAG was to provide
PRPs, municipalities, regulatory agencies, special interest groups, and individuals with
the opportunity to participate in the Superfund process at the Lowry Site. Participants
exchanged ideas and points-of-view, and reviewed planning documents, technical memo-
randa, data, and other site-specific information.
TAG meetings were held on a monthly basis through the spring of 1993. TAG members
decided to discontinue the monthly meetings in April of 1993 since major activities at the
Lowry Site, including the RI/FSs for ODs 2&3 and ODs 4&5, had been recently
completed.
DENlOO1539D.WP5
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4.4 Outreach Program
In 1987, BPA began issuing periodic updates and fact sheets to the public, other regula-
tory agencies, local governmental entities, PRPs, and community groups (see Table 4.1).
These updates/fact sheets reported on the progress of Superfund activities at the Lowry
Site. Since that time, 12 updates and numerous fact sheets on specific topics have been
issued. These special topic fact sheets have included summaries of site-specific baseline
risk assessments and proposed plans for remediation of the Lowry Site.
In September 1991, an 18-minute video of the Lowry Site was produced by EPA and was
made available for use by the public. The video's purpose was to explain the basic his-
tory of the Lowry Site, the Superfund process, the status of the studies to date, and to
provide a tour of the entire site.
Volume 1 (OUs 1&6) of the Baseline Risk Assessment was issued for public comment in
February 1992. BPA received significant public comment on Volume 1 and amended the
document with a Response to Comments, dated August 20, 1993.
Volumes 2A and 2B (OUs 2&3 and OUs 4&5) of the Baseline Risk Assessment were
issued for public comment in December 1992. The final volume, Volume 2C (sitewide
issues, lead, and radionuclides), of the Baseline Risk Assessment was issued for public
comment in April of 1993. On July 2, 1993, BPA issued a Response to Comments docu-
ment for Volumes 2A, 2B, and 2C.
Issuance dates for the RI reports, FS reports, and proposed plans were as follows:
RI Reports FS Reports Proposed Plan
OUs 1&6 March 1992 October 1992 November 1992
OUs 2&3 May 1993 May 1993 September 1993
OUs 4&5 February 1993 May 1993 September 1993
A public comment period for the OUs 1&6 proposed plan was held from November 23,
1992 to March 1, 1993 and a public meeting was held on December 8, 1992 at
Eagl~rest ~igh School. The initial 30-day comment period was extended twice (30 days
each bme), m response to requests from the community.
For the OUs 2&3 and OUs 4&5 proposed plan, a public comment period was held from
September 1, 1993 to November 29, 1993 and a public meeting was held on
September ~1, 1993 at Eaglecr~st Hi~h School. The initial 30-day comment period was
extended twice (30 days each time), m response to requests from the community.
DENlOOI539D.WP5
4-2
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Comments which were received by EP A prior to the end of each of the public comment
periods, including those expressed orally at the public meetings, are addressed in the
Responsiveness Summary for OUs 1&6, and in the Responsiveness Summary for OUs
2&3 and 4&5, which are attached to this Record of Decision. This decision document
presents the selected remedial action for the Lowry Landfill Superfund Site in Arapahoe
County, Colorado, chosen in accordance with CERCLA, as amended by SARA and, to
the extent practicable, the NCP.
Historically, the following publications have reported on the progress of Superfund-
related activities at the Lowry Site: The Denver Post; the Rocky Mountain News; Up the
Creek; Westword; the Denver Business Journal; Aurora Daily Sentinel; Community
Accent; the Wall Street Journal; Colorado Daily; the Financial Times of Canada; the
Littleton Independent; Littleton Report; Englewood Sentinel; the Salt Lake Tribune;
Superfund Week; Colorado Association of Commerce and Industry; the Colorado
Statesman; Wastetech News; and the Boulder Daily Camera.
4.5 Technical Assistance Grant
SARA provides that technical assistance grants may be awarded to groups who may be
affected by a Superfund site. The purpose of these grants is to foster informed public
involvement in decisions related to a site by providing funds for a particular group to hire
independent technical advisors.
In September 1989, a Technical Assistance Grant was awarded to the Citizens Against
Lowry Landfill (CALL). This grant was used to fund reviews and analyses by technical
experts.
4.6 Information Repositories
Since 1987, Lowry Site documents and reports have been maintained in two information
repositories (libraries). These repositories are accessible to the public and are at the
following locations:
.
EP A Superfund Records Center
999 18th Street
5th Floor North Terrace
Denver, Colorado 80202
(303) 293-1807
.
Aurora Central Public Library
14949 East Alameda
Aurora, Colorado 80002
(303) 340-2290
The EP A Superfund Records Center contains the complete Administrative Record. The
Aurora Central Public Library houses pertinent documents that may be of interest to the
public.
DENlOOlS39D.WP5
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Table 4-1
Lowry Landf"III Superfund Site
Fact Sheets and Updates Page 1 of 2
Date Docmnent Contents
January 1985 Lowry Landfill Fact Sheet Activities to be carried out during the RIIFS.
June 1987 Superfund Program Fact Sheet Covered results of the Phase I RIIFS and planned
Update, Lowry Landfill RIIFS activities for the Phase IT RIIFS.
Phase IT
May 1988 Superfund Fact Sheet, Lowry Addressed an Engineering Evaluation/Cost
Landfill Site, Contaminated Analysis (EE/CA) for the Surface Water Removal
Surface Water Action (SWRA), announced a public comment
period during May and June, and announced a
public meeting on May 26, 1988.
June 1988 Lowry Landfill Information Reviewed the Lowry Site and the six Operable
Update No.1 Units (OUs) that divided the Lowry Site for
Phase IT activities.
October 1988 EP A Superfund Program, Update Reviewed RIfFS activities, the Lowry Coalition,
No.2, Lowry Landfill Superfund and radioactivity at the Lowry Site.
Site
July 27, 1989 Lowry Landfill Superfund Site, Reviewed the results of the PEA.
Preliminary Endangerment
Assessment
January 1990 Lowry Landfill Information Reviewed RIfFS activities and presented the
Update No.3 cleanup schedule.
May 1990 Lowry Landfill Information Further reviewed the Lowry Site, the OUs, and
Update No.4 the cleanup schedule.
Septemberl990 Lowry Landfill Information Revised the cleanup schedule, presented the de
Update No.5 minimis settlement, and reviewed RIIFS activities.
January 1991 Lowry Landfill Information Reviewed RI/FS activities and asbestos disposal.
Update No.6
April 1991 Lowry Landfill Information Continued the review of RI/FS activities.
Update No.7
June 1991 Lowry Landfill Information Continued the review of RIIFS activities.
Update No.8
September 1991 Lowry Landfill Information Announced the video, a risk assessment
Update No.9 workshop, and updated RIIFS activities.
August 1991 Surface Water Removal Action The construction schedule and engineering of the
Fact Sheet SWRA were discussed.
April 1992 Draft Baseline Risk Assessment Explained the baseline risk assessment process and
for ShaUow Ground Water and the findings for OUs 1/6.
Subsurface Liquids
June 1992 Lowry Landfill Information Updated RIIFS activities and revised the cleanup
Update No. 10 schedule.
July 1992 Surface Water Removal Action Announced a meeting to discuss final design
Notice of Public Meeting plans.
DENlOOlS276.WPSIl
4-4
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Table 4-1
Lowry Landfill Superfund Site
Fact Sheets and Updates Page 2 of 2
Date Docmnent Contents
November 1992 Lowry Landfill Information Reviewed the status of the OUs and featured a
Update No. 11 summary of the Draft Phase III FS Report for
OUs 1/6.
November 1992 Proposed Plan for Operable Units Reviewed and analyzed the final remedies
1 and 6: Shallow Ground Water proposed for OUs 1/6.
and Subsurface Liquids and Deep
GroundWater
November 1992 Notice of Public Comment Period The public comment period was extended twice; it
Extension for the Proposed Plan ended on March 1, 1993.
for Operable Units 1 and 6
December 1992 Draft Baseline Risk Assessment Reviewed the findings of the baseline risk
for Landfill Solids, Landfill Gas, assessment for OUs 2/3 and 4/5.
Soils, and Surface Water and
Sediment Operable Units
April 1993 Lowry Landfill Information Updated the cleanup schedule, the status of the
Update No. 12 OUs, and other activities.
August 1993 Proposed Plan for OUs 2/3 and Reviewed and analyzed the final remedies
4/5 proposed for OUs 2, 3, 4, and 5.
September 1993 Notice of Public Comment Period The public comment period was extended twice; it
Extension of the Proposed Plan ended on November 29, 1993.
for Operable Units 2, 3, 4, and 5
DENlOO1S276.WPS/2
4-5
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Section 5.0
Scope and Role of Operable Units
-------
Section 5.0
Scope and Role of Operable Units
The NCP recommends the use of operable units (OUs) in situations in which early actions
are necessary to achieve quick risk reduction; when phased analysis is necessary for the
size or complexity of the site; or to expedite completion of total site cleanup. An au
may be a discrete action that comprises an incremental step toward comprehensively
addressing site problems.
The Lowry Site was divided into six OUs based on the complexity of the contamination
problems and the size of the site. At the Lowry Site, OUs were established for each of
the environmental media as follows: au I-Shallow Ground Water and Subsurface
Liquids; au 2-Landfill Solids; au 3-Landfill Gas; au 4-Soils; au 5-Surface
Water and Sediments; and au 6-Deep Ground Water. To facilitate effective implemen-
tation of the RIfFS activities, the OUs were grouped and studied as follows: OUs 1&6,
OUs 2&3, and OUs 4&5.
The primary threats to human health and the environment posed by the Lowry Site
consist of exposure to and contamination by landfill gas, waste-pit liquids, drums, ground
water, and contaminated seepage in the former unnamed creek drainage. Other threats
arise from contaminated landfill solids, soils, sediments, and ground water. This ROD
summarizes the alternatives considered for all threats and presents the final selected
sitewide remedy to address these threats. The overall cleanup strategy at the Lowry Site
is to reduce current or future exposure to: landfill gas; waste-pit liquids; seepage in the
unnamed creek drainage; and contaminated ground water. Landfill gas, seepage, and
ground water will be contained, collected, and treated. Drums, drum contents, and
contaminated soils in the former tire pile area will be excavated, treated, and disposed of
offsite in a permitted disposal facility.
The selected sitewide remedy is an integration of interim remedial measures and remedies
for all the OUs and comprehensively addresses all contaminated media at the Lowry Site.
As discussed in the site history section of this ROD, EPA has previously selected interim
remedial measures to address the seepage in the unnamed creek and the migration of con-
taminated ground water in the alluvium underlying the unnamed creek drainage. The
migration of contaminated ground water in the alluvium has been addressed through the
construction and operation of the ground-water barrier wall and treatment plant. Primary
threats from organic and inorganic contaminated seepage in unnamed creek have been
addressed through implementation of the SWRA, which included an upgrade of the exist-
ing ground-water treatment plant.
The interim remedial measures have been integrated into and are key elements in the
selected sitewide remedy. Other key elements of the selected sitewide remedy include: a
gas collection and treatment system to address the primary threat of landfill gas and gas
migration offsite; barrier walls to contain and treat waste-pit liquids and contaminated
DEN 1 OOIS39F.WPS
5-1
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ground water; excavation, treatment, and disposal of contaminated solids within the for-
mer tire pile area; containment of landf1l1 solids through maintenance of the existing
cover and by the addition of 2 feet of cover on the north face of the landfill; and contain-
ment of soils by maintaining vegetative covers. This selected sitewide remedy will
achieve the sitewide cleanup strategy and partially satisfies the preference for treatment as
a principal element.
DENlOO1539F.WP5
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Section 6.0
Summary of Site Characteristics
-------
Section 6.0
Summary of Site Characteristics
This section provides an overview of the Lowry Site's contamination, including the
source, nature and extent, concentrations, and volume of contamination. In addition,
potential surface and subsurface pathways for contaminant migration are summarized.
Actual routes of exposure and exposure pathways are discussed in Section 7.0. A general
overview of the Lowry Site is presented in Section 2.0.
6.1 Extent of Contamination in Affected Media
The contaminant source discussions are presented by each OU, unless otherwise noted.
The primary sources of contamination at the Lowry Site have been identified as subsur-
face liquids, waste pits, landfill solids, sewage sludge, injected leachate from Pond 3
(eliminated during implementation of the SWRA), sprayed leachate, and landfill gas.
Between 1964 and 1980, Lowry Landfill accepted solid and liquid municipal and indus-
trial wastes including hazardous substances. Prior to 1976, trenches would first be filled
with liquid waste, and then backfilled with solid waste. This method was known as co-
disposal. Once filled with waste, a trench would then be covered with soil from the
Lowry Site. In approximately 1976, this co-disposal technique was reversed with solid
waste first being placed in the trench. Following compaction of the solid waste, the
trench would be filled with liquid waste. Once the trench was full, it was covered with
soils from the Lowry Site. The reason for the change in method was to promote more
immediate absorption of the liquids into the solid waste, and to minimize potential fire
hazards created by the open trenches of liquid. The co-disposal waste pits are located in
Section 6 within the western two-thirds of the landfilled area and former tire pile area
(Figure 6-1).
In addition to the co-disposal and sanitary landfilling techniques, other waste disposal
procedures employed at the Lowry Site included sewage sludge land application and
leachate land application (leachate injection) on the northern and north-central portions of
Section 6, respectively.
Over time, some of the contaminated liquid originally placed into the pits has seeped out
of the pits and has mixed with the surrounding solid wastes, ground water, and surface
water.
DENlOO153Al.WP5
6-1
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6.1~1 OUs 1&6: Shallow Ground-Water and Subsurface
Liquids, and Deep Ground-Water Operable Units
6.1.1.1 Sources 0/ Contamination
Waste pits and landfill solids within and underneath the landfill mass (source area) are the
primary sources of ground-water contamination at the Lowry Site. Although media
interactions among ground water, soils, surface water, and sediments were studied, the
focus of the following discussion is the interaction among ground water, waste pits, and
landfill solids.
6.1.1.2 Nature and Extent 0/ Contamination
The hydrogeologic setting underneath the Lowry Site is described in Section 2.0, and in
the RI report. There are two major ground-water systems: shallow ground water (which
includes the subsurface liquids); and deep ground water. Hydrogeologic studies have
shown that the majority of the ground water under the Lowry Site flows laterally to the
north. A less significant vertical gradient is present within and between aquifers; it
predominantly flows in a downward direction. Vertical gradients generally decrease from
south to north and with depth at the Lowry Site.
A variety of contaminants, including organic chemicals and trace metals, have been
detected in the shallow ground water directly beneath the Lowry Site. There are several
residential wells approximately 2 miles downgradient of the Lowry Site that have been
investigated for possible contamination from the ground water at the Lowry Site. To
date, there has been no evidence of contamination in these wells.
Data from ground-water monitoring wells and waste-pit liquid well Points were grouped
together on the basis of hydrogeology, derived from the Lowry Coalition well groupings,
as follows: shallow ground-water monitoring wells and waste-pit liquid well points in the
source area; ground-water monitoring wells completed in the weathered Dawson Aquifer
outside the source area; ground-water monitoring wells completed in the unweathered
Dawson Aquifer outside the source area; deep ground-water monitoring wells; and
upgradient ground-water monitoring wells outside the source area.
The estimated areal extent of contamination is based on data from existing monitoring
wells. Certain portions of the Lowry Site (such as the northwest comer of the Lowry
Site, which is outside of the waste pits source area) lack sufficient numbers of wells for
an exact determination of the horizontal and vertical extent of contamination. The extent
of contamination in these areas will be further refined during the remedial design.
6.1.1.2.1 Waste-Pit liquid Within the Source Area. The waste pits and associated
liquids contain the highest average concentrations of nonhalogenated VOCs (volatile
organic compounds), and SVOCs (semivolatile OCs; base/neutral and acid), metals, and
radionuclides, as compared to other contaminated ground waters at the Lowry Site.
D~1001S3Al.~
6-2
-------
Toxicity Characteristic Leaching Procedure (TCLP) analyses were performed on waste-pit
liquids and waste solids. The liquid analyses were performed by filtering the liquid
samples and analyzing the filtered materials. Several VOCs, SVOCs, and one pesticide
and metal were detected at or above regulatory levels in the extract from these samples.
Based on RCRA toxicity characteristic testing, waste-pit solids and liquids are hazardous.
Analytical results from waste-pit liquid samples indicate a high degree of spatial variabi-
lity across the Lowry Site. On the basis of field observations and liquid-level measure-
ments recorded during sampling, immiscible phase liquids have been identified in 10 of
the approximately 70 waste pits. These phases included both light nonaqueous phase
liquids (LNAPLs) and dense nonaqueous phase liquids (DNAPLs). The amount and type
of nonaqueous phase liquids (NAPLs) present varied considerably between well points,
and in some cases between measurements in the same well point. Figure 6-1 shows the
waste-pit well points that contained either LNAPLs or DNAPLs.
The mobile-phase NAPL contamination extent appears to coincide with the horizontal
extent of the waste pits (Figure 6-1) and to the vertical extent of the weathered system.
6.1.1.2.2 Saturated Refuse Within the Source Area. Saturated refuse samples were
collected from three borings within the source area. VOCs, semivolatiles, and metals
were detected. Compared to the waste-pit liquid, waste pit solids, and source area
shallow ground-water analytical results, the saturated refuse (saturated solids outside of
the waste pits) samples contained similar contaminants at similar or lower concentrations.
6.1.1.2.3 Shallow Ground Water in the Weathered System within the Source Area.
VOCs were the most prevalent organic compounds present in the ground water in the
weathered system. The SVOCs, pesticides/PCBs, and additional organic compounds
were also present in samples from ground water in the weathered system inside the
source area. Results of sample analyses indicated that radionuclides, trace metals, and
inorganics were frequently present in samples collected from monitoring wells at levels
that exceeded Lowry Landfill upgradient values.
In general, similar compounds were detected in samples from waste-pit liquid and ground
water in the weathered system. Concentrations of parameters present in samples from
waste-pit liquid generally exceeded concentrations of the same parameters present in
samples from ground water in the weathered system. The extent of horizontal contamina-
tion coincides with the boundaries of the weathered system within the source area as
shown in Figure 6-2. The vertical extent of contamination extends to the base of the
weathered system throughout the source area. The base of the unweathered system is
estimated to be 30 to 50 feet below the ground surface.
6.1.1.2.4 Shallow Ground-Water Upgradient of the Source Area. Parameters detected
in samples from the upgradient ground-water monitoring wells (B519, B520, MWOO3,
MWOO4, MWOO5, MW22, U509, and U51O) include organics, trace metals, and
radionuclides. The organics present in samples from upgradient monitoring wells are
common laboratory contaminants, and the concentrations are most likely indicative of
DENlOOlS3Al.WPS
6-3
-------
laboratory artifacts. However, one perimeter upgradient monitoring well, U-510, has
confirmed organic contamination, indicating contaminant migration toward the southern
boundary of the Lowry Site. Recent sampling of Well U-51O revealed seven organic and
eight inorganic compounds. This well is screened from 48 to 58 feet below ground
surface.
6.1.1.2.5 Shallow Ground Water in the WeIlJhered and Unweathered Systems Outside
01 the Source Area. Contamination detected in the weathered system outside of the
source area and unweathered Dawson include VOCs, SVOCs, radionuclides, and trace
metals. The lateral extent of contamination (Figure 6-2) appears to be generally confined
to three areas. The areas are located near (1) unnamed creek (Well AI16A), (2) the
existing banier wall (Wells B214, GW1074, A115, GWl144, GWI06A, B307, and
U701), and (3) east of the Command Post (Well MW23). Maximum contamination was
detected in Well B712, which is located at the toe of the landfill mass, approximately 100
yards to the east of unnamed creek.
6.1.1.2.6 Deep Ground Water. The deep ground-water system includes the water-
bearing zones beneath the Dawson Aquifer, which includes the upper and lower Denver
aquifers. Contaminants within the deep ground-water monitoring wells include organics,
dissolved NAPL compounds, radionuclides, and trace metals. Several deep monitoring
wells were installed at the Lowry Site. Results from these wells indicate that the extent
of impacted deep ground water is limited to Wells B504 and C702Q2, shown in
Figure 6-3. These wells are screened at 105 to 125 feet, and 162 to 172 feet below
ground surface, respectively. The average concentration of organics in deep ground
water is substantially lower compared to the average concentrations of organics in shal-
low ground water. The presence of contaminants in monitoring well C702Q2 was
generally not confirmed between sampling events.
Computer modeling results indicate that, in the absence of any remedial action, it would
take approximately 200 years for contamination from the source area to reach the lignite
layer. The areal extent of contamination in deep ground water is provided in Figure 6-3.
6.1.1.3 Concentrations of Contaminants
Tables 6-1 through 6-5 present the chemical concentration data summary for each hydro-
geologic grouping.
6.1.1.4 Volume Estimates
The total volume of potentially contaminated ground water at the Lowry Site was esti-
mated as follows:
6.1.1.4.1 Shallow Ground Water. The volume of potentially contaminated shallow
ground water is estimated to be in the range of 900 million to 2 billion gallons. A broad
range is observed because of differing methods of estimating the volume of contaminated
DENlOO153A1.WPS
6-4
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shallow ground water. Twelve million gallons of the ground water are considered to be
in the saturated alluvium.
6.1.1.4.2 Deep Ground Water. The volume of potentially impacted deep ground water
is estimated to be in the range of 93 million to 1.2 billion gallons.
6.1.1.4.3 Saturated Refuse. The volume of liquid within saturated refuse was estimated
to be approximately 14 million gallons.
6.1.1.4.4 Waste-Pit Liquid. The current volume of liquid within the saturated waste pits
is estimated to be approximately 95 million gallons.
6.1.2 OU 2: Landfill Solids
The following includes discussions of landfill solids OU media in both the landfill mass
and the former tire pile area.
6.1.2.1 Source 01 Contamination
The primary sources of contamination of the landfill solids in both the landfill mass and
the former tire pile area are the waste-pit liquids and the municipal refuse.
6.1.2.2 Nature and Extent 01 Contamination Within the Landfill Mass
The nature of contamination within the landfIll mass includes volatile and semivolatile
organics, metals, pesticides, PCBs, and radionuclides. The extent of landfill solids is
shown in Figure 6-4. The former landfIll occupies approximately 195 acres and is esti-
mated to average 80 to 100 feet in thickness. The areal extent of the landfill is shown in
Figure 6-1.
6.1.2.3 Concentrations 01 Contaminants Within the Landfill Mass
The detection frequencies of the following VOCs exceeded 10 percent: 1,1-dichloroe-
thane; 1,1, I-trichloroethane; 1,2-dichloroethane; 2-butanone; 4-methyl-2-pentanone;
acetone; chloroform; methylene chloride; tetrachloroethylene; and trichloroethylene. The
data generally show the highest concentration of VOCs to be associated with unsaturated
solids samples from within or below suspended waste pits, thereby reflecting the impacts
of residual waste-pit liquid contamination. Concentrations of VOCs are usually lowest in
post-1980 samples. No samples exceeded established standards for TCLP VOCs.
Phthalates were the most commonly detected SVOC. There is no apparent areal
distribution trend (for example, similar ranges of concentrations from areas with
suspended liquid waste pits as with areas with saturated waste pits, medical waste, or no
waste pits). There is however, a general vertical trend with the highest phthalate
concentrations found in the post-1980 solids. In general, phthalate concentrations
DEN1OO1S3Al.WP5
6-5
-------
decreased with depth. Phthalates are common plasticizer chemicals and the noted trend
may, therefore, reflect the increased use of plastics and plastic containers over time.
Phenol was detected at the highest frequency. As with the phthalate, there is no apparent
areal distribution trend for phenol; however, there does not appear to be a general
decrease in phenol concentrations with depth. A number of polyaromatic hydrocarbons
(PARs) were also detected.
PCBs and pesticides were also detected in some of the samples. There are no distinct
areal or vertical distribution trends for any of the metals. The concentrations of the more
toxic metals (such as arsenic, cadmium, chromium, and mercury) are generally below
50 mg/kg with the exception of lead, which had a maximum detection of 1,410 mg/kg.
No samples exceeded established standards for TCLP metals. For radionuclides, the
values measured are generally low and within the background concentrations established
for soils as part of the ODs 4&5 RI.
Table 6-6 presents a summary of chemicals detected in unsaturated solids within the
landfill mass and their concentrations.
6.1.2.4 NaJure and Extent of Contamination Within the Fonner Tire Pile
Area
The former tire pile area, occupying approximately 54 acres, is located immediately north
of the main landfill mass and is shown in Figure 6-4. The measured depth to ground
water in this area generally ranges from approximately 2 to 11 feet. The tires that were
formerly stockpiled in the area have been shredded and placed into a monofill cell by
WMC under contract to Denver. As part of the SWRA effort, an engineered collection
system and cover were placed in the unnamed creek drainage. Waste pit disposal
operations occurred in three general areas within the tire pile area.
A geophysical investigation consisting of an electromagnetic survey was performed in
conjunction with confmnatory trenching to estimate the number of buried drums in the
former tile pile area of the Lowry Landfill. Nine confmnatory trenches were excavated
in areas identified as anomalies by the geophysical investigation. Twelve corroded drums
were encountered in four of the six anomalous areas. Data from the trenching efforts
suggest that there may be as many as 1,350 buried drums. Appendix E of the feasibility
study for ODs 2&3 estimates that approximately 19 percent (257 drums) of the total
estimate of buried drums may contain liquids. Based on treatability study results, the
feasibility study also suggested that, on the average, approximately 5 gallons of liquid
may be present in each of the estimated 257 liquid-filled drums; this provides the basis
for an estimated yield of a total liquid volume of no less than 1,300 gallons of liquid
waste.
DEN I OOI53A1.WP5
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6.1.2.5 Concentrations of Contaminants Within the Former Tire Pile Area
Organic chemicals including volatile organics, semi-volatile organics, pesticides, PCBs,
and inorganics including metals and cyanide were detected in subsurface solid samples in
the former tire pile area. A summary of these chemicals appears in Table 6-7. The
unsaturated solids are a source that contributes to ground-water contamination.
6.1.2.6 Volume Estimates
Landfill solids volumes were calculated for pre-1980 solids (co-disposal practices were
ceased on August 11, 1980), post-1980 solids, and total solids. Both the total saturated
solids and total unsaturated solids volumes were calculated for the landfill mass. Esti-
mated landfill solids volumes are as follows:
.
Volume of pre-1980 Solids-3.2 x 10<' yd3g
Volume of post-1980 Solids-8.9 x 106 yd3
Total Volume of Solids-1.2 x 107 yd3
Volume of Saturated Solids-2.2 x lOS yd3
Volume of Unsaturated Solids-1.2 x 107 yd3
.
.
.
.
These calculations show that about 74 percent of the total solids at the Lowry Site were
disposed of after 1980, and approximately 98 percent of the total solids volume is
unsaturated.
6.1.3 OU 3: Landfill Gas
6.1.3.1 Source of Contamination
The primary sources of contaminants in the landfill gas are subsurface liquids, saturated
and unsaturated landfill solids, and leachate.
6.1.3.2 Nature and Extent of Contamination
As with other municipal solid waste landfills, methane gas and other gases are generated
at the Lowry Site from the degradation of solids and chemical constituents present in the
landfill mass. RI data were used to characterize the nature and extent of methane and
other gases generated at the Lowry Site. Following the completion of the low permeabi-
lity landfill cap in 1992, methane gas excursions outside the landfill perimeter have been
observed on a regular basis at Wells GMP-3, GMP-6A, GMP-7, and GMP-9. Figure 6-5
shows the general source and extent of contamination.
Ambient air was sampled during the Phase I, Phase II, and ASC monitoring programs.
No evidence of site-related contaminants was found in the ambient air data.
DENIOOIS3Al.WP5
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6.1.3.3 Concentrations of Contaminants
Frequently detected chemicals in landfill gas include 1,1, I-trichloroethane, 1, I-dichloro-
ethane, carbon disulfide, chloroethane, methylene chloride, tetrachloroethylene, trichlor-
ethylene, methane, and vinyl chloride. These compounds were detected most frequently
in both waste-pit gas samples and samples from refuse located above waste pits. Concen-
trations of the VOCs generally decreased with distance from the waste pits. The decrease
in concentrations is attributed to the dilution of the volatiles carried within the methane
generated from the refuse. Concentrations of contaminants in samples collected at the ,
refuse surface, in areas with underlying waste pits, were approximately 1.5 to 10 times
lower than concentrations in samples taken directly above the refuse/waste-pit interface.
Concentrations of contaminants in samples collected at the refuse surface in areas without
underlying waste pits were approximately 1 to 8 times lower than concentrations in sam-
ples taken from the same zone in areas with underlying waste pits.
Gas concentrations detected within the former tire pile area are considerably higher than
those detected outside the landfill mass. For example, benzene was detected at a maxi-
mum concentration of 18,000 p.g/m3 within the former tire pile area and 500 p.g/m3
outside the landfill mass; vinyl chloride was detected at a maximum concentration of
680,000 p.g/m3 within the former tire pile area, and 7,000 p.g/m3 outside the landfill
mass.
Headspace samples taken with Summa canisters from monitoring wells in the waste pits
provide an .indication of the amount of chemicals volatilizing from the ground water.
Chemicals detected in greater than 50 percent of the samples include 1,2-dichloroethy-
lene, benzene, chloroethane, ethylbenzene, toluene, xylene, and vinyl chloride. These
data provide information on the mixture and amount of chemicals emitted from ground
water and those that contribute to landfill gas volumes.
Volatile organics were also collected in gas samples taken outside the landfill mass but
within the Lowry Site boundary. Soil gas samples taken from outside the landfill mass
indicate the presence of five chemicals: 1,1, I-trichloroethane, benzene, ethylbenzene,
toluene, and xylene. The compounds detected in these samples were also detected in gas
samples taken from within the landfill mass or from gas probes adjacent to the landfill.
Of the nine locations from which samples were analyzed, three samples showed
consistent and positive detects-two on the north, and one on the southwest side of the
landfill. Chloroform was the most frequently detected chemical (7 out of 10 samples) in
the remaining gas monitoring wells. All other chemicals were detected in two or less
samples.
Combustible gas was first detected in perimeter gas monitoring wells in August 1991.
Four out of 13 probes (GMP-3, GMP-6A, GMP-7 and GMP-9) were found to contain
measurable levels of combustible gas. Since August 1991, the frequency of monitoring
has been increased to a monthly basis and the same four gas wells have continued to
show detectable levels of combustible gas, although the percent of detected methane
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varies from month to month. Table 6-8 summarizes the methane data obtained from the
perimeter gas monitoring wells.
Table 6-9 presents the summary data for all the landfill gas samples.
6.1.3.4 Volume Estimates
In 1987, WMC conducted a gas recovery study for the Lowry Landfill and estimated gas
generation rates were shown to be approximately 170 standard cubic feet per ton of solid
waste per year (scf/tn/yr). The Lowry Site contains approximately 5 million tons of
solids. Therefore, the gas generation rate is estimated to be 1,600 standard cubic feet per
minute (scfm). This generation rate is an "estimated maximum" and is expected to
decrease with time.
6.1.4 OU 4: Soil
6.1.4.1 Source of Contamination
Four distinct areas of the Lowry Site (not including the landfill mass) were used for
waste disposal (Figure 6-6) and contribute to surface soil contamination. The areas are
distinct either because of the type of waste disposed or the method of disposal. These
areas are identified as: the sewage sludge application/leachate injection area; the sewage
sludge application area; the leachate spraying area; and the former tire pile area.
Figure 6-6 depicts the approximate boundaries of each area.
6.1.4.2 Nature and Extent of Contamination
For the purposes of this discussion, surface soil is defined as zero to 12 inches in depth.
Subsurface soil is defined as soil from a depth of 1 to 10 feet.
6.1.4.2.1 Sewage Sludge ApplicaJion/LeachoJe Injection Area. This area is
approximately 200 acres in size and is in the northern portion of Section 6. Of the areas
in which surface soils were sampled, this area exhibited the greatest number of organic
chemicals detected. Thirty-eight organic chemicals were detected, although 68 percent of
these were detected only once or twice. PCB-1260 was detected in eight samples within
this area. This is the only area of the soils media in which PCB-1260 was detected in
more than one sample. Although 2,3,7,8- TCDD was not detected in samples from this
area, nine other more highly chlorinated dioxins and furan isomers were detected in one
sample out of two analyzed for these compounds.
Eighteen inorganic constituents were detected, with one constituent, selenium, detected
only once in 11 samples. The inorganic chemicals that were detected were distributed
throughout the area. The highest concentrations of inorganic constituents were detected
in two adjacent sample locations near the. unnamed creek channel. Eighteen samples
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were analyzed for radionuclides and four naturally-occurring isotopes were detected in the
majority of ~ese samples.
6.1.4.2.2 Sewage Sludge Application Area. This area is comprised of approximately
40 acres. Nine organic chemicals were detected in surface soil in this area. Five of
these chemicals-benzoic acid, chloroform, 4,4'-DDD, di-n-octylphthalate, and toluene-
were detected only once with methylene chloride and phenol detected twice. Only
4-chloroaniline and bis(2-ethylhexyl)phthalate were consistently detected in samples from
this area. Background inorganic constituents, except selenium and thallium (no positive
detections), were detected consistently throughout the area. No samples were analyzed
for radionuclides from this area.
6.1.4.2.3 Leachate Spraying Area. The leachate spraying area occupies an area of
approximately 4 acres. Three organic chemicals, benzene, bis(2-ethylhexyl)phthalate,
and methylene chloride were each detected once out of the seven samples in surface soil
taken from this area. Chloroform was detected in one of two samples. Cyanide,
selenium, silver, and thallium were not detected above the detection limit, and mercury
was detected once. All other typical inorganic constituents were detected consistently in
samples from this area. Radionuclides were detected in the two samples taken.
6.1.4.2.4 Former Tire Pile Area. The former tire pile area occupies an area of
approximately 54 acres. Thirty-four organic chemicals were positively detected in
samples from this area. The following pesticides were detected in more than one sample:
alpha chlordane, DDT, dieldrin, endrin aldehyde, gamma chlordane, and methoxychlor.
Alpha chlordane in more than half of the sample locations and nine P AHs were detected
at one sample location along unnamed creek. Twelve inorganic constituents were
detected at sample locations throughout the former tire pile area. Mercury was detected
in two samples, selenium in one sample, and cadmium, cyanide, silver, and thallium
were not detected over the detection limit in this area. Soil samples were not analyzed
for radionuclides.
6.1.4.2.5 Subsurface Soil. Organic chemicals, including VOCs, pesticides and PCBs
were detected infrequently in subsurface soil. The following organic chemicals were
detected at a frequency greater than 10 percent: 2-butanone, 4-chloroaniline, acetone,
methylene chloride, bis(2-ethylhexyl)phthalate, DDT, endrin, and PCB-1260. Subsurface
samples from the sewage sludge application area, leachate spraying area, and tire pile
area were analyzed for radionuclides. Eight radionuclides, including plutonium-239,
potassium-40, strontium-90, thorium-228, -230, and -232, uranium-234, and uranium-2-
38, were detected at a frequency of 100 percent. Lead-21O was detected at a frequency
of 75 percent.
6.1.4.3 Concentrations 01 Contaminants
The following summaries are based on an evaluation of data collected from the zero to
12-inch soil horizon and the subsurface soil interval of 1 to 10 feet.
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6.1.4.3.1 Sewage Sludge Application/Leachate Injection Area. The minimum and
maximum detected and the mean concentrations of organic chemicals detected in surface
soil samples taken from this area are presented in Table 6-10. The mean was calculated
by using one-half the detection limit as a place holder for samples without a value above
the detection limit. Compared to the other areas identified under au 4, this area
displayed the maximum concentrations of organics. Specifically, the following three
chemicals detected at concentrations exceeding 1,000 J.'g/kg: 4-chloroaniline,
bis(2-ethylhexyl)phthalate, and PCB-1260.
Summary data for inorganic constituents are also presented in Table 6-10. Maximum
concentrations of inorganics for the Lowry Site, excluding manganese and aluminum,
were detected within this area.
6.1.4.3.2 Sewage Sludge Application Area. Summary data for organic chemicals in
surface soil samples are presented in Table 6-11. The most frequently detected
chemicals, 4-chloroaniline and bis(2-ethylhexyl)phthalate had maximum concentrations of
about 500 J.'g/kg. Table 6-11 also presents inorganic summary data. The maximum
concentration of manganese for the Lowry Site was detected in this area.
6.1.4.3.3 Leachate Spraying Area. Summary data for organic chemicals in surface soil
samples from the leachate spraying area are presented in Table 6-12. There were four
organic chemicals that were each detected only once. The maximum concentration of
these chemicals was less than 25 Ilg/kg. The exception was bis(2-ethylhexyl)phthalate,
with a maximum concentration of 215 Ilg/kg. Table 6-12 also presents inorganic
summary data. Concentrations of inorganic constituents are generally lower than those
detected in other areas.
6.1.4.3.4 Former Tire Pile Area. For this area, the minimum, maximum, and the mean
concentrations of detected organic chemicals in surface soil samples are presented in
Table 6-13. Although six pesticides were present in more than one sample, none were
detected at concentrations greater than 2 Ilg/kg. Table 6-13 also presents inorganic
summary data. The maximum concentration of aluminum for the Lowry Site was
detected in the former tire pile area.
6.1.4.3.5 Subsurface Soil. The data summary for subsurface soil, presented in
Table 6-14, does not distinguish between areas. All subsurface soil samples were
grouped because of the limited number of samples and detected constituents. No
consistent distribution of organic chemical concentrations could be determined with
available sample data. In general, inorganic constituent concentrations decrease with
increasing depth. In the sewage sludge application area, zinc, lead, cadmium, nickel, and
chromium exhibited lower concentrations in subsurface soil than in the zero to 12-inch
horizon. In the leachate spraying area, concentrations of inorganics remained relatively
unchanged throughout the soil profile. The maximum concentration of arsenic,
18,000 JLg/kg, was detected in the leachate spraying area at the 4.5- to 6-foot interval.
Two radionuclides, thorium-228 and potassium-40, were detected in background samples.
DEN1OOI53AI.WP5
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Reported on site concentrations for these radionuclides are comparable to the background
concentrations.
6.1.4.4 Volume Estimates
For purposes of estimating the volume of soil in au 4, an aerial extent of approximately
103 acres (excluding the former tire pile area) and an average excavation depth of 15 feet
was assumed. This depth was based on the detection of arsenic at 18,000 p.g/kg at 6 feet
below ground surface and the depth of the current borrow area. The total volume of soil
in au 4 is estimated as approximately 2.5 million cubic yards.
6.1.5 OU 5: Surface Water
The SWRA, implemented in 1992, eliminated the off site migration of contaminated seep-
age from unnamed creek. The SWRA collects the unnamed creek base flow in a subsur-
face drain and maintains flows that are in contact with the ground-water table until the
ground water is captured at the barrier wall. At the barrier wall, the base flows are
pumped to the existing ground-water treatment plant. The existing ground-water
treatment plant was recently upgraded to treat larger quantities and a more expansive list
of contaminants. A soil cap was placed within the on site unnamed creek channel as well.
6.1.5.1 Past Source of Contamination
Seeps have historically been observed in locations along the banks of the unnamed creek
near the center of Section 6. The sources of these seeps are believed to be the waste
pits, ground-water discharge, and seepage from the toe of the landfill. The seeps contri-
buted to perennial contaminated surface water flows in the unnamed creek. Prior to the
SWRA, surface water would flow into the area previously occupied by Pond 3, which
was located along the unnamed creek upstream of the barrier wall. Previously, water
that collected in Pond 3 would infiltrate through the bottom of the pond and into the
subsurface (upgradient of the barrier wall); it was then collected for treatment. During
periods of high precipitation, Pond 3 would overflow; this caused contaminated runoff to
flow within the offsite portion of the unnamed creek channel.
6.1.5.2 Nature and Extent of Contamination
Prior to implementation of the SWRA, numerous sampling events detected at least
20 organic chemicals in surface water in unnamed creek - from the toe of the landfill to
the area previously occupied by Pond 3. Within the unnamed creek drainage, between
the area previously occupied by Pond 3 and the confluence of Murphy Creek, the
detection of organic chemicals was infrequent and generally not reproducible because of
dilution and low perennial flow. Inorganic constituents follow the same concentration
pattern as organics; twice the number of inorganic constituents were detected (with a
frequency over 50 percent) in Section 6 than beyond the area previously occupied by
Pond 3.
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6.1.5.3 Concentrations of Contaminants
The highest concentrations of organic chemicals that were detected in unnamed creek
prior to implementation of the SWRA were found in samples collected in the surface
drainage between the toe of the landfill and the area previously occupied by Pond 3.
Significantly lower concentrations were detected in samples downstream of the area previ-
ously occupied by Pond 3. Historical data are summarized in Table 6-15 according to the
geographic location of the samples:
.
Toe of the landfill to the area previously occupied by Pond 3 (Group 1);
.
Downstream of the area previously occupied by Pond 3 to the confluence
of unnamed creek with Murphy Creek (Group 2); and
.
Beyond the confluence with Murphy Creek to Section 30 (Group 3).
Generally, concentrations of inorganic constituents were also highest in unnamed creek
between the toe of the landfill and the area previously occupied by Pond 3. These histor-
ical data are also summarized in Table 6-15.
6.1.5.4 Volume Estimates
Through implementation of the SWRA, measurable quantities of surface-water flow
within unnamed creek have been eliminated. The SWRA collection system is designed to
collect ground-water flow of up to 13 gallons per minute (gpm). Although the volume of
ground-water flow into the collection system is not known, the treatment plant has report-
edly processed approximately three million gallons in a 9-month period.
6.1.6 OU 5: Sediments
Implementation of the SWRA eliminates the offsite transport of surface water and sus-
pended sediments in unnamed creek. As part of the SWRA, a soil cap was constructed in
the on site unnamed creek channel (see Figure 11-2 for approximate location of the
collection system soil cap). Contaminated sediments within unnamed creek are currently
covered by the SWRA soil cap.
6.1.6.1 Past Source of Contamination
The potential sources of sediment contamination in the unnamed creek were discussed in
Subsection 6.1.5.1. Sediments within the unnamed creek in Section 6 are now covered by
the SWRA soil cap.
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6.1.6.2 Nature and Extent of Contamination
Prior to the implementation of the SWRA, at least 15 organic chemicals were detected in
sediments within the onsite unnamed creek channel. Few organic chemicals were
detected in sediments downstream of the area previously occupied by Pond 3.
Inorganic constituents were detected above background levels throughout the creek chan-
nel as well as beyond the confluence of unnamed creek and Murphy Creek.
6.1.6.3 Concentrations of Contaminants
The concentrations of sediment contaminants are discussed separately for Section 6 sedi-
ments and Section 31 sediments.
6.1.6.3.1 Section 6. Prior to implementation of the SWRA, elevated concentrations of
organic chemicals were detected in the sediments of unnamed creek. Specifically, these
chemicals were found in samples collected from the portion of the creek channel that is
within the former tire pile area. For example, 1,1, I-trichloroethane, toluene, and total
xylenes were detected at maximum concentrations greater than 100 mg/kg. Significantly
lower organic concentrations were detected upstream of this area, in the general vicinity
of the toe of the landfill. All sediments in Section 6 were covered as part of the SWRA.
Elevated concentrations of barium, chromium, and lead were detected in sediment sam-
ples from within 'the creek channel in the former tire pile area, in close proximity to the
waste pits on the east side of the former creek. Historical data for sediments in Section 6
are summarized in Table 6-16.
6.1.6.3.2 Section 31. Samples collected downstream of the barrier wall in Section 31
exhibited inconsistent detections of organic chemicals. The area downstream of
Section 31 can be divided into two smaller geographical segments to more easily discuss
contaminants detected:
.
From Section 31 to confluence with Murphy Creek; and
.
From the confluence with Murphy Creek to Section 31 northern boundary
line.
Fifteen organic chemicals were detected in the segment from Section 31 to the confluence
with Murphy Creek. Eleven of these chemicals were detected only once. Of those
chemicals detected more than once, bis(2-ethylhexyl)phthalate had the highest detection
frequency at 50 percent. PCBs, toluene, and acetone had detection frequencies between
30 and 40 percent. With the exception of 2,4-dinitrophenol (detected once out of 11
samples), which was detected at 2.7 mg/kg, maximum concentrations of these organic
compounds were below one mg/kg.
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Five organic compounds were detected in the segment from the confluence with Murphy
Creek to the northern boundary of Section 31. Three of these were detected only once.
Bis(ethylhexyl)phthalate and octochlorodibenzodioxin were detected more than once (three
and two detections, respectively). The maximum concentrations of these organic
compounds was 0.3 mg/kg for di-n-butylphthalate which is at the detection limit. The
maximum concentration of octochlorodibenzodioxin was 0.00012 mg/kg.
Seventeen inorganic constituents (out of 19 analyzed for) were detected within the
segment from Section 31 to the confluence with Murphy Creek. Two, cyanide and tin,
were detected only once. The remaining fifteen compounds had detection frequencies
greater than 40 percent. Two inorganic chemicals not detected in these sediment samples
were antimony and silver. Average concentrations of most inorganic constituents were
approximately the same as those calculated for Section 6. However, average
concentrations of barium, chromium, mercury, and lead were 1/2 to an order of
magnitude lower than those calculated for Section 6.
Eighteen inorganic constituents (out of 19 analyzed for) were in the segment from the
confluence with Murphy Creek to the northern boundary of Section 31. Four
constituents, silver, iron, antimony, and tin were detected only once. The remaining
constituents had detection frequencies between 20 and 88 percent. Cadmium was not
detected in a single sediment sample from within this segment. Average concentrations
of most inorganic constituents were approximately the same as those calculated for
Section 6. However, average concentrations of arsenic, barium, chromium, manganese,
mercury, and lead were 1/2 to an order of magnitude lower than those concentrations
calculated for Section 6.
6.1.6.4 Volume Estimates
According to the au s 4&5 feasibility study, the SWRA soil cap covers an area of
approximately 320,000 square feet in size. This estimate includes the areas previously
occupied by Ponds 3 and 4 (pond 4 was previously located directly west of the existing
treatment plant). The volume of contaminated sediments that were left in place and
covered by SWRA soil cap was not estimated. The volume of sediments in the unnamed
creek segment of Section 31 is estimated to be 23,700 cubic yards.
6.2 Surface and Subsurface Pathways of Migration
Conceptual models were developed for each au and were designed to detail potential
contaminant sources, potential routes of migration, and contaminant fate and transport.
The models focused the RI/FS site characterization activities and formed the basis of the
pathways identified in the baseline risk assessment(s).
The sources of contamination at the Lowry Site include subsurface liquids, waste pits,
landfill solids, sewage sludge, injected surface water from Ponds 2 and 3, sprayed surface
DEN1OO1S3Al.WPS
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water from Pond 2, and landfill gas. These sources have released, and will continue to
release, con~nants to environmental media. The environmental media may then act as
secondary sources for distributing contamination throughout the environment and to
human and environmental receptors.
Sampling of these media was conducted during the pre-Phase I, the Phase I and Phase n
RI, and the OUs 1&6, 2&3, and 4&5 Additional Site Characterization (ASC) efforts to
assess media interactions and their potential as secondary sources of contamination.
Interactions were evaluated as part of each OU RI Report. However, only the significant
pathways of migration are discussed here. Significant pathways have been chosen based
on their contribution to site risk.
The significant pathways of migration include subsurface liquids to shallow ground water,
subsurface liquids and shallow ground water to surface water and sediments, volatiles
from subsurface liquids to landfill gas, landfill solids to landf1l1 gas to the atmosphere,
leachate from landfill solids to shallow ground water, contaminated surface water to
shallow ground water, and shallow ground water to deep ground water.
6.2.1 Subsurface Liquids to Shallow Ground Water
Contaminants from the waste pits have migrated into both the weathered Dawson shallow
ground-water system and the unweathered Dawson formation. Migration primarily
occurs in a horizontal direction. In certain areas of the Lowry Site, waste pits and shal-
low ground water have no hydraulic separation. As a result, the waste-pit liquids and
shallow ground water have co-mingled.
Although contaminants in the waste-pit liquids are similar to contaminants in the shallow
ground water, individual comparisons of analytical results between waste pit well points
and adjacent shallow ground-water monitoring wells indicate variable trends. The differ-
ences in contaminant occurrence and concentrations between the well points and adjacent
monitoring wells could result from one or more of the following conditions: variability
in geology; lack of contaminant migration, or variability in the rate, volume, and pattern
of contaminant migration from the waste pits; location of a waste pit in relation to the
water table; the influence of other waste pits on the monitoring wells; the presence and
possible migration of multiple liquid phases in the waste pits; or contaminant migration
from the waste pit along pathways not encountered by the adjacent monitoring wells.
6.2.2
Subsurface Liquids and Shallow
Ground Water to Surface Water and
Sediments
Data collected during Phase I and Phase n investigations confirmed that the shallow
ground-water and subsurface liquids located within or just below the landf1l1 mass flowed
to the north and discharged to the unnamed creek. Available data also support the con-
clusion that the shallow ground-water and subsurface liquids in the former tire pile area
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were discharged to the surface water through seeps located along the banks of unnamed
creek. These ground-water discharges contributed to the base flow within unnamed
creek. For the area north of the fonner tire piles, available data support the conclusion
that the shallow ground-water system was recharged through surface water infiltration.
Subsurface sand channels have also been identified at the Lowry Site. These sand chan-
nels promote enhanced subsurface fluid flow and provide another mechanism for subsur-
face liquids to intermingle with shallow ground water.
The majority of the organic compounds which were detected in the shallow ground water
and subsurface liquids were also detected in surface water, and at a similar frequency of
detection. A similar correlation was observed between au 1 and sediments, although
au 1 contaminants were typically detected less frequently in sediments. Concentrations
of organics detected in shallow ground water (aU 1) were typically higher than in either
the surface water or the sediments.
Based on the correlation between contaminant levels in sediments and their location with
respect to waste pits, contaminants from the waste pits have migrated through the ground
water and discharged via seeps to surface water in the unnamed creek.
Although analytical results indicate that ground-water discharge to the unnamed creek has
historically impacted surface water and sediments onsite, implementation of the SWRA
has isolated these media and prevents offsite migration of contaminated surface water.
6.2.3 Volatiles from Subsurface
Liquids to Landfill Gas
Analyses have shown that both the waste pit and refuse gas samples contained similar
organic compounds. Because these two types of samples were collected at various eleva-
tions above the waste pits, the results indicate that: (1) within the refuse, waste-pit
vapors and waste-pit gases are highly mobile and widely dispersed in the subsurface;
and/or (2) that the refuse serves as a source for gas generation.
Similar types of volatile organic compounds are seen in the landf1l1 gas and source area
shallow ground water, and substantiate that there are interactions between the media.
6.2.4 Landfill Solids to Landfill Gas to Atmosphere
Significant pathways of migration between the landftll solids, landfill gas, and the atmo-
sphere are as follows:
.
Gas produced within the landfill mass migrates primarily by advective flow
toward the landf1l1 perimeter and into the atmosphere.
DENlOOI53Al.WPS
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.
The highest contaminant concentrations and the greatest number of contam-
inants at the perimeter tend to occur closest to the landfill margin.
.
The composition and concentrations of VOCs detected in perimeter areas
are consistent with gas compositions within the landfill mass.
.
Soil gas VOC concentrations in the former tire pile area are consistent with
VOC concentrations within the waste pits; gas contamination by VOCs in
the former tire pile area is characterized by localized sources.
6.2.5 Contaminated Surface Water
to Shallow Ground Water
Seepage within unnamed creek transported contaminants to the sediments and surface
water. The potential contribution of contamination from sediments and surface water to
the shallow ground water depends on the amount of precipitation runoff and recharge that
occurred within unnamed creek.
Prior to implementation of the SWRA, surface water was observed to infiltrate into the
subsurface through the bed of unnamed creek. A comparison of surface water data (from
the area previously occupied by Pond 3) to ground-water data (from wells located along
the unnamed creek north of the fonner tire pile area) indicates recharge from contamin-
ated surface water potentially impacted ground water in the former tire pile area. Com-
parisons indicate, however, that other sources, including subsurface liquids, have also had
a significant impact on ground-water quality in this area. Completion of the SWRA
eliminated potential recharge to the shallow ground-water system underlying unnamed
creek.
6.2.6 Shallow Ground Water to Deep Ground Water
Hydraulic gradient data indicate that downward vertical gradients exist between the
shallow and deep ground water. Chemical analyses from the deep ground water indicate
the presence of low levels of organic contamination near Wells B504 and C702Q2. A
potential exists for contaminated shallow ground water to migrate to the deep ground
water.
DENlOOI53A1.WPS
6-18
-------
LEGEND:
Area of Waste Pit Containing Liquids
Bound!!.ry of Area of Suspected
Liquid Waste Pits (Source Area)
Landfill Boundary (Fence Line)
Former Landfill Boundary
Well Points with NAPLs Observed
EAST
HAMPDEN
AVENUE
'.'''''''>~,<~~'~''
Active .-.
Asbestos'-
Disposal ~
P~ ;";:
";.<;:.
:f):
#;.
.
----
...---..-......
.
., ,
!!
rt;
't< I
;k.
;t: ,
.:>: !
--I
''';:; I
~!
;.:" I
.<; ----,
Barrier Wall
-"""'_"H''''__'--'''- . m.."_~ ,-.--.- ..,,- . "
."..,
..
Existing Ground-Water Treatment Plant
Section 31
...~..J ~'
-~l
!
------ - - - - - --------~.
\~A
':~
\~
\~
..,~
'.n
:m
.",
.,,:-
,.WMC
Maintenance
Facility
Section 6
. ----'-
!
~--
"
>-.
l.'\
J /.1
" J
, (
J
) I
J I
,il
I
/ /
/1 I
.~ .
'.\. ..J
./ .
i
j'/ Tire Shreds
Monotill
,
~
, 1
I
I
k
~;
: .~----_...
1
,
, ;
, .-
j {
, ,
; ~
i i
'"
--
"" I
..---r""''''" ,
. ( ,;,
"""'--",,, .-------.........,"" - / : \
/------ \,
': .
!: ,/ .1 ~ \_'~.~_..~..",,-"<\../ .,...,
!~ ~
,':.' ( . I ~ ~ )
. \ :t //
ii \ /
:, , -. /
\\, ..... ,
\ " I
"'. . I
\. \ - .
\" \ r-'
'::~~.\ -.... I "".. \
'~~.~ ~ ---' ---
':::;.:::- - - - ./ 'i OF REFUSE
"':':'::::::,:.:}~,~.=.:.:::.::::-:.:.=.=-_..~~~~':~-='-'~'=~'~.=.~~.= - - J
Not to Scale
.;:.'?
.,
~
~
N
~
'., '"
. ',-,~.~ ;'-"< ",'-~'-'
'" ,:" ,,..' .? --'
EAST QUINCY AVENUE
The locations shown are approximate.
DEN Graohllowrv Ron/171
6-19
Figure 6-1
APPROXIMATE WASTE-PIT LOCATIONS
1965-1980 AND WELL POINTS WHERE
NON-AQUEOUS PHASE LIQUIDS WERE
OBSERVED
LOWRY RECORD OF DECISION
-------
EAST
HAMPDEN
AVENUE
Gate
Active
Asbestos
Disposal
Pit
l N\)r\LLlNG AREA
o~Ni LA ,-
C\)?<' r
_nn.._....................""""'''.''.''''.''...'''')
j
j
.I
Section 31
...-...--. .-...---..---.
o
<
o
a:
CD
::>
....
u
z
::>
c:s
\e>
;co
'a>
,J"'"
"i
;,.. 11'
i.,)
~ /'
J )
i1 I
) ,
.I I
.I,
:, "
i \
",,\_/
V Tire Shreds
~; --
I I i
:. J:
--
~ "" ,
\ , .../"'l
\ ,.r ,\
I: (~I-.~I ~~.;~--~///-\ i
II: II~ :
HI -2 ,
n , - I
H \ .:t /
~i \ --A /'
;\ \ ., I
\\ \ I
\" \ I
\", \
~ I
';" \ ,..-
\""~ -- ' ',dB ~
';;;',~ -- .
;;;""~ I .1
""~'" ...... - -- .-. - ..... -- -' : :
'X:', : .
'::~~., "\ OF REFUSE j 1
"':'~~~:'::r,;:'=':::'=::::=::::",,"~~\ .---~~.=~.~-='~-~= -=: -_J
Inactive
Asbestos
Disposal
Pit
... :
N
1
Not to Scale
EAST QUINCY AVENUE
LEGEND:
.. Area 01 Waste Pit Containing Uquids
- - - Boundary 01 Area 01 Suspected
Uquid Waste Pits (Source Area)
-u- Landfill Boundary (Fence Une)
- Approximate Extent 01 Shallow Ground Water Contamination
The locations shown are approximate.
DEN GraphILowry ROD/172
6-20
Figure 6-2
EXTENT OF CONTAMINATED SHALLOW
GROUND WATER
LOWRY RECORD OF DECISION
-------
(~ ~ f>.NDfILLlNG A.REA. J
::::; : C\}~~€.~i L ..- /'
:r : ( /
~iii ~ l. ! / /' 8arr..~ WaJl
:;;; : '.............--..---.-.-.....-./ li*r' ~ .....,.......
HA~ApSriEN ;~:: ~ Existing Ground-Water Treatment Plant"""""'.. \ , /',..... ,.....'"
-,~:~~:*,~:,,,w',~~-=T=:-=--=--=_:::_-=~:--'" " """" 31
'.': : ~~ :: '\<,-H~"'''H ---,---------
~ I i ~i E~~- =2\'~ =~:"6 I
ill J
i:i~:~ C702Q1 j
=~ 1 i
p; i; ! GW110A !
0: i?j B504 i / ~~~~
~I ., -- 'I rI !
ED ;;;;;; .~ .:~ \.: '. .'/''''''f'.... i \ !
:::>:;:;;; . \\_~
~:~~::: H \ /.1 Il i j
Z :;;;;; ~ i ;.:;..-.-....-..-.::: / \ \ { ;
~.~:~:: u / ~ "- ./', !
: I { I ~ \/~"'-""-,<---'_/ \!
II / . I ~ \ j
n, ~ 1 ~j
Ii ~ -, 1 II
n \ ;: /1 ! :
E; \ /:1
:1 \ -I I ~:
\\ \ ' H
,-, - :,
\... " ~)j
'~"'" \ ".. "\ f :
'\;;:.>..\. -- I ',tII!!!I!II \ \ !
'''::.;;:' ~ I""""'" : ~
.':;~..."""" -- - -- - -- -- -' ~ I
,~ i J
'<-;;"" "'\ OF REFUSE ;' 'I
-'"'''' \..\v.\ -""""''''''''''- .,.'
""'::."r:.:.=:::-=-::~..::::.:..:.;.;...:.:::::::~_..... -----==--='.. --~
;=;:::
.:.:.'
~:~:~:
i
I
':;:;:;:::~~~~r':-:':':':':':':':':';':':':':';':':':'[[[
EAST QUINCY AVENUE
[[[
LEGEND:
I11III Area 01 Waste Pit Containing Liquids
aou/Jdary 01 Area of Suspected
liquid Waste Pits (Source Area)
-------
EAST
HAMPDEN
AVENUE
AdioJe
Asbestos
Disposal
Pit
Existing Ground-Water Treatment Plant
.. ~fi~t.:.w~._u_u_u_-- ;~~
"~j' i '~.~~""~ Mai~~enance \~
; ~ r: FaCility ',c.
- \~
::'\,",-~-".J' :i
J-"" \1,,'
- '
"-
(
I
I
/
1"/
r
I
1/1
I
I I ", 'II
1-" V
.--/
.....~..._, ...~ .",..-,.-
! _...._-_..~
, ,
i
~~
~
~~
,7";
'd~.
$
~
'f
~
"-...----.'
"
"
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~,
'~
~~
y~
. . ,..,.'.
, '- .'O:;;:'-::,'~:,,"';~/;:'¥~'..~. ~ ~"'", '. """'~.'<' ';"
EAST QUINCY AVENUE
LEGEND:
_u- Landfill Boundary (Fence line)
Extent 01 Unsaturated Solids Contamination
~
Approximate Extent 01 Contamination within
the Former Tire Pile Area
The locations shown are approximate.
DEN GraphfLovvry ROD/173
Barrier Wall
-
Section 31
Section 6
,-
i
: ,Tire Shreds
I / Monofill
:/
/1
I
"
Closed
Landfill Area
N
!
Not to Scale
..\\ OF REFUSE
\.\\'t.
,
,
,
-------------------
. -.-".~," ;,q ;-.' -,.t'
-.-, ;y;,n,~~"":'; ,', ...~'}:;,~"t"
6-22
Figure 6-4
GENERAL SOURCE AND EXTENT OF
CONTAMINATION WITHIN UNSATURATED
SOLIDS WITHIN THE FORMER TIRE PILE AREA
LOWRY RECORD OF DECISION
-------
,
,
I
,
,
~\\ OF REFUSE I
o GMP~ :
--------II----------------_-J
NOf\\.L\NG AREA /
C\)~~~N\ Lr-. i .--.---...,
Barner Wall
"__'_~--'''-'----''~'''~-'''_'_H''''_''H''''
.. 'M ..~ ,.-
EAST
HAMPDEN
AVENUE
Gate.
~'
~ '.'__._-
AdNe ~ J', :
Asbestos j!' - - -,
Disposal ~ I" - .
Pit ~GMP-2 I
I! ;
, '
i '-----.'
o
o
I
o
,
I
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,
I
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1 .... ./ .....
~ I! ""
., 1 ' 1
II,! 1
'i/; 1
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i; 1
l' 1
i' 1
,j 1
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/ 1
j. I
. . \. I
'.....::... .' '
.. '~..:.' I
-I
"
. GMP-4A
./
.-.
"
Closed Landfill Area
-
}
"'I";
"'':?:''A~{..'''~ ~.~.£...",.,..".-<,; ."--. ._~
Section 31
,
,
I
,
I
,
,
I
,
,
I
,
,
I
.: GMP-12
I
/
,
" Tlfe Shreds
/ MonofiD
/ :
I
,
,
I
,
,
I
,
,
I
., GMP-11
,-
!
i
,
,
.! GMP-10
,
I
,
,
I
,
,
I
,
,
I
N
t
., , - '~" "(', ~"*~ .'.
.' .'-', ~.M'''~~~_'." ~ :'.' T."':":"..-'"
NOTm SCALE
-I
-------
I':J:
~! .
~! .'
EAST ~j i
HAMPDEN ~,c,
I" ,
AVENUE ik.-.' ..
, ...i~'::::.;..."~"~"'''9''.,r~'1' .'¥/o
;~ !
~1
~,/:1
Gale
Active
Asbestos
Disposal
P~
:::I"
...JI
~'~.':
'"
:::I ,.
~":
~.
I
I
~
~J
II
~.
LEGEND:
DFILLING AREA ./
\'li LAN ,---------',
CU?-?-~ !
~;;'g GrouOd-Wa,.,T,eatmeo' p'ant--'~--:-~
0i' .~;,', ,-', , \;:\ Command Post
rj .. ''Q".- ' !
:.::,', Tire Pile ::',:. "" " "" "'"
""""""""lI11i'~t~~~~~~~~~
...,
.'~~~'-~'.-.. .~. -.-..~..__. ...~.~.~_..~..
1:
,;
"
"
"
':
.:
if
,;
.;
\ i
\~....
\\
"'"'''''' i I
'~'<.,.- \ OF REFUSE ."J
"-':'~:'~':r;~':::::':.::::.:::.:,::=.;~..._:~\ .".~~='~'~'='~'~'='~.~'=- -. J
, . .
Sewage Sludg8 Applicatiorit
Leachate Injection Area ..
'-~.~._..._..
Leachate
Spraying
Area
, .-
, ,
I;
i;
, :
. :
.-.-...-...~. '-~~n._-."-"'.
--'
Closed
Landfill
Area
,.-./"(. - ;, ~f':>~.!"'Y""":-,:,,, e.,. t'J. h
, -:~...,:;1',:,:~~:,,~~;~,"';~:)
,-;' .:~;; I.--';:,~;;'~U:""'-;'~.tf<-;...v:.(.~::-:-
-------
Table ~J
SaIJuDIIry ofCaemlcal Cooc:eatration Data for
Waste Pit UqDids WeD Points and Shallow GI'OUIId-Water
MODItoriD& Wells III the Soarc:e Area
P82eJ of4
Freqaency
of Mlnlmam (c) MaDmIDD (c)
No. of No. of Detects (b) Detected Detected Averace (d)
<'heIIIIeIII Name (a) A....- Detects (%) Concentration Concentration Detect
Orpnics (pgI1)
1,1,1- Tric:hloroctbaae 141 58 41 3.00000o 2768511.3 101.41
1,1,2,2- TcIrac:hloroetba 140 1 1 66.00000o 66 18
1,1,2- Tric:hloroctbaae 141 3 2 3.00000o 104.1 16.71
1,I-Dic:hloroelbaDe 140 76 54 2.00000o 1051621.6 219.44
1,I-Dic:hlorocdryleae 140 49 35 0.800000 140000 41.75
1,2,3,4,6,7,8-Heptacblordibemop-Dioxin 39 29 74 0.000050 0.928 0.0013
1,2,3,4,6,7,8-HeptadJlorodibcmofuraD 39 25 64 0.000020 0.142 0.0001
1,2,3,4,7,8,9-HepladJlorodi~Dioxin 39 19 49 0.000003 0.0167 0.000041
1,2,3,4,7,8,9-HepladJlorodibeuzofuran 39 13 33 0.000020 0.0167 0.000032
1,2,3,4,7,8-HexadJlorodi~Dioxin 39 13 33 0.000007 0.0082 0.000016
1,2,3,4,7,8-HexadJlorodibeuzofuran 39 22 56 0.000003 0.0172 0.000032
1,2,3,6,7,8-Hexac:hlorodi~Dioxin 39 25 64 0.000010 0.0486 0.0001
1,2,3,6,7,8-Hexac:hlorodibeuzofuran 39 13 33 0.000003 0.0048 0.000013
1,2,3,7,8,9-Hexac:hlorodibeuzofiuaD 39 3 8 0.000008 0.00022 0.000009
1,2,3,7,8-PcoIac:hlorodibeozo.p-Dioxin 39 9 23 0.000004 0.0026 0.000010
1,2,3,7,8-PcoIac:h1orodibeuzofuran 39 8 21 0.000009 0.0013 0.000009
1,2,4- Tric:hlorobcmenc 120 5 4 8500000 1663.3 13.13
1,2-Dic:hlorobcnzene 120 18 15 4.00000o 180 13.52
1,2-Dic:hloroelbaDe 141 77 55 3.000000 1800000 221.56
1,2-Dic:hloroctbcne (TOtal) 141 51 36 1.00000o 160000 61.10
I,2-Dic:blocOfnOJ4ut 141 11 8 1.00000o 268.2 16.31
1,4-Dic:hlorobenzene 120 21 18 2.00000o 321.1 15.08
2,3,4,6,7,8-HexadJlorodibeuzofuran 39 12 31 0.000010 0.0034 0.000014
3,4,7,8-PcoIac:h1orodibe 39 11 28 0.000007 . 0.0019 0.00001l
3,7,8- Tetrac:hlorodibeazodioxin 41 10 24 0.000005 0.0011 0.000007
3,7,8- Tetrac:hlorodibeuzofuran 41 29 71 0.000002 0.0014 0.000030
4,5-T 25 5 20 2.300000 90 2.45
,,4,5-TP 27 8 30 1.00000o 48.5 3.36
4,5- Tric:hloropbenol 97 1 1 18.00000o 18 59
4,~ Tric:hloropbeuol 99 2 2 13.000000 15 16.50
4-D 26 3 12 46.000000 2450 13.55
4-Dic:b1oropbenoI 99 8 8 22.000000 164 21.70
~4-DimeIhyIpbeooI 98 28 29 9.000000 3900 47.11
~4-DinitropbeooI 85 1 1 500.00000o 500 47
~ButaIIone (MEK) 127 47 37 17.000000 230000 383.85
-ch101'0111\phtb
-------
Table 6-1
Sammary of CbemkaI Couc:eatratioa Data for
Waste PIt Uqalds WeD Points IIIId ShaDow GI'OIIDd-Water
MoDitoriD& Wells iD the Source Area
PIIB 2 of
FrellDeDCY
of MiDimum (c) Mulmam (c)
No. of No. of Detects (b) Detected Deteded Averace(d)
CIemkaI Name (a) os. Detects (%) Couc:eatration Conc:eatratlon Detect
(2.Propanooe) 140 68 49 4.00000o 2984870 1041.47
Aldicarb 22 1 5 60.000000 60 2.
Aldicarb Sulfoxide 22 1 5 23.00000o 23 2.1
Alpha Chlordane 71 3 4 0.380000 1.2 0.19
Alpha-BHC 102 3 3 0.150000 0.71 0.07
AniliDe 20 3 15 21.000000 41 57.31
e 116 1 1 3.400000 3.4 14
140 97 69 1.00000o 974172.9 131.S3
Beozo(a)ADthnceDe 116 1 1 83.800000 83.8 13
Beazoic hid 76 24 32 15.600000 30200 315.42
Beazyl Alcobol 96 8 8 7.200000 1930 30.40
bis(2-Cbloroetbyl)Etbcr 115 1 1 3.00000o 3 15
bis(2-EtbyIbexyI)Pbtba1ate 117 27 23 1.00000o 21500 43.17
. c:bIorometbane 141 1 1 3.00000o 3 13
Bromoform 140 1 1 13.00000o 13 17
1phtha1a1e 116 6 5 18.100000 1010.3 16.71
Carbaryl 23 5 22 2.00000o 97 3.34
..... Ie 30 2 7 7.00000o 12 15.43
.
23 3 13 6.00000o 640 3.13
Carbon Disulfide 141 14 10 15.00000o 14180.2 46.66
Carbon TeIracbloride 141 6 4 14.600000 26000 21.91
Cblorobeazcoe 141 19 13 2.000000 5200 18.29
139 25 18 2.00000o 257.1 36.54
Cbloroform 141 20 14 0.600000 56000 26.06
Cbloromethane 141 3 2 2.00000o 18 20.91
116 2 2 20.200000 72 12.76
:is-l,3-Dic:blO{opj....-e 141 1 1 5.000000 5 16
DeIta-BHC 102 1 1 0.030000 0.03 0.060
[)i..N-ButyIpbthaIat.e 116 11 9 2.000000 266.6 13.93
IDi-N-OctyIpbtbalate 116 4 3 5.700000 1205.8 14.78
118 1 1 4.00000o 4 12
IDibromocb101~ue 141 1 1 7.00000o 7 16
IDicamba 26 6 23 0.800000 250 2.46
Dieldrin 102 3 3 0.140000 1.3 0.13
Didhylpbtbalate 101 12 12 6.800000 340 19.06
Eudosulfan n 102 1 1 0.640000 0.64 0.12
Eodrin 102 3 3 0.060000 1.1 0.13
Eodrin Aldehyde 11 2 18 1.00000o 2.98 0.17
Eodrin Ketone 101 3 3 0.760000 1.78 0.14
141 71 50 3.00000o 3514995 107.22
EtbyIeoe Glycol 26 1 4 650000.00000o 650000 2,OOC
Etbyleoedibromide 24 3 13 0.120000 0.28 0.02
Fluonmtbeoe 117 3 3 25.900000 200 13.18
117 7 6 2.00000o 241.4 13.14
Gamma Chlordaoc 71 1 1 0.620000 0.62 0.71
Gamma-BHC (Lindane) 102 4 4 0.025000 1.02 0.07
Heptac:blor 101 2 2 0.470000 1.5 0.07
DEN05S.xLS
6-26
-------
Table 6-1
Summary ofCbemical CoacentratiOD Data for
Waste PIt Uqalds WeD PoIDts and SbaDow Ground-Water
MooitorinE Welb In the Soarc:e Area
P8j!e30f4
Freqaeocy
of Minimum (c) Muimum (c)
No. 01 No. of Deted3 (b) Detected Detected Avel'll&e (d)
CIIeIakaI Name (a) "'-'-- Detects ("Ie) Conc:entratioD CODc:entratioD Detect
Heptaddor Epoxide 102 2 2 0.240000 0.94 0.06
HeptacbloroclibeazodioxiDs 22 3 14 0.090000 0.23 0.0023
HeptaddmKb"bemofilraDs 68 33 49 0.000061 0.784 0.00054
IkxadIlmKbDeazoclioxiDs 78 21 27 0.000020 0.098 0.00017
Hex:acblmKb"bemofilraDs 82 23 28 0.000006 0.195 0.00016
118 12 10 3.00000o 1376340 23.25
MCPA 24 1 4 650.000000 650 400
Methoxychlor 102 2 2 0.120000 14 0.36
MetbyI- Cblaride 140 56 40 3.00000o 440000 107.37
N-NitrosodipbeayIa 117 6 5 10.00000o 5972 17.84
Naphtbal- 127 53 42 2.00000o 109622 31.66
OctacbloroclibeazoclioxiDs (Total) 61 36 59 0.000021 14.93 0.01
ibcazofiIrans (Total) 61 29 48 0.000154 1.16 0.00071
PCB-1242 (Aroclor 1242) 107 1 1 19.350000 19.35 1.2
PCB-126O (Aroclor 1260) 108 5 5 15.00000o 493 1.39
PeatacblmKbDeazoclioxiDs (Total) 75 13 17 0.000009 0.0301 0.000036
Peutacbloroclibeozofiaraus (Total) 77 24 31 0.000005 0.0657 0.000091
Peutacbloropheuol 95 8 8 4.00000o 4125 81.11
117 15 13 4.200000 1690 22.26
~l 102 38 37 3.00000o 29000 60.92
~ 117 5 4 36.300000 230 14.30
~ 140 4 3 17.000000 28101.4 20.10
rrelracbloroclaDeazociioxin (Dioxin) 77 17 22 0.000002 0.0064 0.000021
Tdraddoroclibem.otUnm (Dioxin) 89 24 27 0.000008 0.0107 0.000060
Tdraddoroetbylcae 141 51 36 0.900000 341360.5 84.61
Tolucae 140 97 69 0.900000 10938360 627.65
Total HeptacblorocIibeP-Dioxin 40 29 73 0.000050 1.73 0.0019
Total XyIaIcs 141 88 62 5.000000 2279915.6 436.11
Trm&-I,3-Dicblo. "1""1""'" 141 2 1 2.200000 3 14.86
Tric:b1oroeIhyIe 141 78 55 4.00000o 772347.3 110.16
V"myt Cbloride 141 48 34 2.600000 1800 54.23
lnorpnks (pgII)
113 83 73 3.500000 310000 3099.21
109 10 9 4.066400 1170 30.53
ArscIIic 105 77 73 2.200000 1550 68.08
Barium 114 109 96 13.900000 16600 410.70
Beryllium 114 12 11 0.870000 12 3.02
~ 44 35 80 80.702200 34700 1504.12
~um 114 45 39 2.500000 517 16.51
(Total) 114 52 46 0.712900 1660 24.99
Cobalt 114 71 62 5.400000 328 30.40
Copper 113 52 46 4.700000 1550 82.07
CyaaicIe 109 26 24 5.300000 6910 37.26
Fenous Iron 21 21 100 200.00000o 1720000 58535.20
f1uoricle 50 34 68 160.000000 1760000 3496.15
Lead 92 45 49 1.00000o 506 36.61
114 113 99 182.00000o 69600 2952.23
DEN055.xLS
6-27
-------
Table 6-1
Sammary olCbemic:al Conceotration Data lor
. Waste Pit liquids WeD Poiats aDd SbaIIow Gromtd-Water
Monltorln: WeDs in the Soun:e Area P8I!e4of'
Frequency
01 MiDimma (c:) Muimum (c:)
No. 01 No. 01 Detects (b) Detected Detected Averqe (II)
0IemiaII Name (a) A_-- Detects (%) CODCeDtration Concentration Detect
Mercury 114 25 22 0.210000 3.3 0.20
Nickel 114 85 75 13.00000o 2000 161.01
Selcoium 102 45 44 1.800000 6540 82.88
iIver 107 19 18 0.660000 78 7.20
Thallium 76 16 21 0.342100 763 29.75
in 9 1 11 200.00000o 200 68
Vaoadium 114 44 39 1.800000 760 74.03
Unc 114 79 69 4.600000 28800 247.26
RadiODuclides (pall)
.. 228 67 2 3 5.000000 80.7 II
IAmericium-241 39 I 3 2.00000o 2000000 79
IAmericium-241 (Alpha) 7 I 14 0.100000 1500000 7.9
Bismutb-214 79 41 52 1.060000 200 13.54
Prium-143 6 6 100 25.00000o 92 43.81
136 59 I 2 1.500000 15 3.7
Cesium-137 68 3 4 l.S00000 19 2.52
~-57 59 I 2 l.S00000 5 2.2
~-60 67 2 3 l.S00000 22 2.49
~124 59 I 2 2.000000 300 12
iIrou-59 67 I I 2.500000 32 3.1
!Lcad-210 2 I 50 3.000000 11 5.7
iLcad-212 20 9 45 3.250000 47 10.55
!Lcad-212-Sismudl 48 10 21 2.500000 108 5.24
iLcad-214 79 39 49 0.904000 . 202.5 16.36
lNeodyuium-147 59 I 2 15.00000o 150 29
rtutonium-239 42 19 45 0.020000 25 0.47
Potassium-4O 89 51 57 25.00000o 1930 153.49
226 12 6 50 0.350000 75.4 2.85
Sodium-22 59 I 2 l.SOOOOO 4 1.9
StrouIium-90 58 6 10 0.000002 4.5 0.44
ThaIlium-208 67 5 7 4.500000 650 7.14
I'horium-228 63 10 16 1.00000o 105 4.70
230 13 10 77 0.040000 75 1.99
I'horium-232 51 25 49 0.035000 146 1.08
ritium 57 45 79 25.00000o 7500 601.39
Uranium-234 13 11 85 0.100000 49 4.02
235 38 4 11 10.00000o 25 17.60
238 45 32 71 0.050000 426.7 2.96
Natural 9 6 67 1.200000 150 5.68
Zircooium-95 60 I 2 2.500000 8 3.8
lNotes:
a. Only c:bemica1s detected at least ooce in the source area well grouping are presented.
b. M~ of c:al~: (number ofsampl~ with detec:tcd CODC:eIItraliooslnumber of samples within this well grouping)
c. MinimumIMaximum detected cooc:eatration values (oaly two figures are significant).
~ Geometric mean of tile median COIICCII1r.diom &om all wells in this well grouping including 1/2 the detection limit for IJODodetects (oaly two figures are
Source: Appeudix A, Baseline Risk Assessment (EPA, 1992). JI
DEN055Ja.S
6-28
-------
Table 6-2
SammaJ:y of Chemic8I CoaceotnUioo Data for
Dowugradieot Weathered DaWSOD MoaitoriDg Wells
Outside of the Soun:e Area
P82e 1 of3
Frequeocy (b)
of MiDimum (c) Maximum (c)
No. of No. of Detects Detected Detected Average (d)
CbemicaI Name (a) . Detects (~) CooceatratiOD CoDCeDtration Detect
Orgaaics ~)
1,1 ,1-Tric:hloroethane 33 16 48 2.80 5300.00 26.27
1,1,2- Tric:hloroelhaDe 33 4 12 3.90 13.00 3.92
1,I-Dic:h1oroethanc 33 14 42 2.50 770.00 14.77
1,I-Dic:hloroethylene 33 12 36 16.00 750.00 13.05
1,2,3,4,6,7,8-Heptac:h1onlibeozc>-p-Dioxin 13 2 15 0.000010 0.000290 0.0000087
1,2,3,4,6,7,8-Heptac:hloroclibenzofuran 13 1 8 0.000002 0.000002 0.0000021
1,2,3,4,7,8,9-Heptac:hl~Dioxin 13 1 8 0.000030 0.000030 0.0000029
i,2,3,4,7,8,9-Heptac:hlorodibeozofuran 13 1 8 0.000008 0.000008 0.0000032
1,2,3,4,7,8-Hexac:hlorodibeozo-p-Dioxin 13 1 8 0.000020 0.000020 0.000002S
1,2,3,4,7,8-Hexac:hlorodibeozofuran 13 1 8 0.000001 0.000001 0.0000018
1,2,3,6,7,8-Hexac:h1orodibeozo-p-Dioxin 13 1 8 0.000020 0.000020 0.0000023
1,2,4- Tric:hlorobeazene 26 1 4 1.30 1.30 5.5
1,2-Dic:hloroethane 33 10 30 5.00 200.00 6.33
1,2-Dic:hloroethene (Total) 33 12 36 5.80 610.00 10.61
1,2-Dic:bloropropane 33 7 21 2.10 75.00 4.92
1,4-Dic:h10r0beazene 26 1 4 10.00 10.00 6.4
2,3,4,6,7,8-Hexac:hlorodibeozofuran 13 2 15 0.000004 0.000004 0.000003
2,3,7,8- Teuac:hlorodibeozofuran 13 2 15 0.000004 0.000007 0.000002
',4-D 11 1 9 1.50 1.50 1.3
2,4-Dic:hlorophenol 24 1 4 5.70 5.70 5.6
2,4-Dimclhylphenol 24 1 4 13.00 13.00 6.0
'-Butanooe (MEK) 26 4 15 2.30 12.00 5.57
2-Hexanone 33 1 3 3.50 3.50 6.6
-Mdhylphenol 24 1 4 8.00 8.00 5.8
...Bromophenyl-Phenyldher 26 1 4 10.00 10.00 6.4
I-Mdhyl-2-PentaDOne (MIBK) 33 1 3 8.70 8.70 7.1
t-Mdhylphenol 24 1 4 13.00 13.00 6.0
i-N'droaDiIine 26 1 4 50.00 50.00 32
~enaphthene 26 1 4 2.00 2.00 5.7
iAc:etone (2-Propanone) 33 6 18 9.80 180.00 11.72
~dic:arb Sulfoxide 11 1 9 1.00 1.00 0.56
33 4 12 5.20 44.00 4.08
Beozo(G,H,I)Perylene 26 1 4 10.00 10.00 6.4
Beuzoic: Ac:id 19 3 16 2.00 9.10 19.60
bis(2-EthylhexyI)PhthaJat.e 2S 3 12 1.00 5.60 5.29
Bromodic:hlorometbane 33 1 3 3.00 3.00 3.5
Bromoform 33 1 3 17.00 17.00 3.9
Carbon Disulfide 33 3 9 10.00 12.00 4.76
Chloroform 33 8 24 2.60 21.00 4.36
Delta-BHC 20 1 5 0.01 0.01 0.02
Di-N-Butylphthalat.e 26 1 4 2.00 2.00 5.7
Dibromoc:hloromethaae 33 1 3 7.00 7.00 3.7
Didhylphlhalat.e 26 1 4 2.00 2.00 5.7
9 1 11 0.10 0.10 0.82
~ylbellUne 33 1 3 38.00 38.00 3.5
DEN056.XLS
6-29
-------
Table 6-2
Summary of Chemical COllC8ltralioo Data for
Dowugradieat Weathered Dawsoa MODitoriag WeDs
Outside of the Source Area
Pue 2 of3
F'reqaeDcy (b)
of MiDimam (c) Maximum (c)
No. of No. of Detects Detected Detected Avenge (eI)
f"heonirAl Name (8) -. Detects (%) CouceDtratioD CoDCeDtraliOD Detect
HeptachlorodibellZOfuraos 13 1 8 0.000004 0.000004 0.0000026
Hexacb1orodibcozodioxiDs 13 3 23 O.(X)()() 1 0.00019 0.()()()(J()6
HexachlorodibeDZOfuraos 13 1 8 0.000003 0.000003 0.0000023
Methylene Chloride 33 12 36 1.60 110.00 6.29
N-Nitroso-Di-N-Propy1amine 26 1 4 0.86 0.86 5.3
OctachlorodibcozodioxiDs (Total) 13 1 8 0.00007 0.00007 0.000030
OctachlorodibeDZOfuraos (Total) 13 1 8 0.000004 0.000004 0.0000053
PeDtachloroclibeDzodioxiDs (Total) 14 1 7 0.00003 0.00003 0.0000041
PelltachlorodibeDZOfuraos (Total) 13 1 8 0.000002 0.000002 0.0000019
Phenol 24 2 8 2.10 3.80 5.86
Pyrme 26 1 4 2.10 2.10 5.7
TelrachlorodibeJlzodioxin (Dioxin) 13 1 8 0.000006 0.000006
Tetrachloroetby1euc 33 14 42 2.00 790.00 12.15
Toluene 33 4 12 1.00 4.00 3.22
l'otal HeptachlorodibeuzcrP-Dioxin 13 1 8 0.0005 0.0005 0.0000079
otal Xyl- 33 3 9 14.00 360.00 6.00
richloroethy1euc 33 14 42 3.00 400.00 10.20
V'myJ Chloride 33 J 3 6.80 6.80 6.2
IDorgauia (,IgJl)
AIumiDum 29 6 21 7.90 507.00 57.51
I\JWmony 29 3 10 0.80 1.60 9.01
IU8enic 29 11 38 3.90 55.20 5.22
Barium 29 19 66 10.72 236.00 36.68
Boron 11 10 91 42.06 661.00 238.54
:::bromium (Total) 29 12 41 0.25 19.07 2.15
~ 28 8 29 0.76 78.00 5.19
~ 28 8 29 1.61 42.21 5.75
fluoride 12 1 8 600.00 600.00 350
~ 29 4 14 0.80 8.00 2.41
28 18 64 8.64 23800.00 72.52
Mercury 29 2 7 0.20 0.48 0.14
Nickel 28 15 54 0.95 138.00 11.16
Selenium 27 11 41 5.00 414.00 10.61
Silver 29 1 3 0.90 0.90 2.6
IbaJJium 26 8 31 0.30 1.60 3.06
Tm 16 1 6 50.00 50.00 20
VUlldium 29 2 7 1.91 24.00 8.16
ZiDc 28 22 79 2.10 250.00 20.98
IlAdinnoclides (pCiJI)
y-l25 13 1 8 3.50 10.00 5.1
AnIimony-l26 13 1 8 3.00 15.00 4.9
BismuIh-214 13 4 31 3.50 32.70 6.7
Cerium-139 13 1 8 1.50 5.00 2.2
Chromium-51 13 1 8 15.00 40.00 2.4
Europium-152 13 1 8 4.00 10.00 5.6
Europium-lS5 13 1 8 4.50 10.00 6.8
DEN0S6XLS
6-30
-------
Table 6-2
Sammuy of Chemical CooceatralioD Data for
DowogradieDt Weathered Dawsoo Mouitoriog WeDs
Outside of the Sourc:e Area
Pue 3 of3
Frequeacy (b)
of MiDDoum (c) Maximum (c)
No. of No. of Detects Detected Detected Average (d)
Chemical Name (8) ~L Detects (1Ji,) Cooceatraoon Concentration Detect
~odiDe-132 13 1 8 10.00 15000.00 100
odiDe-133 6 1 17 10000.00 100000o.00 100,000
[ron-59 13 1 8 3.00 10.00 4.7
140 13 2 15 3.00 20.00 6.05
ILead~212-Bismuth 13 3 23 3.00 17.80 5.20
ILead-214 13 3 23 5.00 24.80 10.13
Mercury-203 13 1 8 1.50 4.00 2.4
t'lepllmium-239 12 1 8 150.00 600000o.00 3,100
Plutonium-239 13 1 8 0.03 0.45 0.15
Potassium-40 13 1 8 25.00 100.00 39
Radium-224 13 4 31 30.00 100.00 49.69
Ruthenium-l06 13 1 8 10.00 40.00 18
Scandium46 13 1 8 2.00 6.00 2.9
ilver-l10 13 1 8 1.50 6.00 2.4
~um-22 13 2 15 1.50 5.00 2.13
troDIium-85 13 1 8 1.50 5.00 2.6
troDlium-90 13 1 8 0.10 2.00 0.34
ecbnetium-96 13 2 15 5.00 1500.00 41.44
1hallium-208 13 1 8 5.00 16.80 6.4
~orium-228 13 1 8 3.00 15.70 4.9
~orium-230 11 2 18 0.04 5.20 0.12
lThorium-232 13 2 15 0.03 0.15 0.06
~m-ll3 13 1 8 1.00 3.00 1.7
II'rilium 13 4 31 20.00 350.00 68.41
~ranium-234 13 11 85 0.20 21.00 2.15
~ranium-235 13 2 15 10.00 40.00 17.43
Uranium-238 13 8 62 0.05 17.00 1.18
Xeuon-131M 13 1 8 100.00 1000.00 260
Xeuon-133 13 1 8 25.00 1500.00 82
ZiDc.{i5 13 2 15 3.00 10.00 4.55
Zireouium-95 13 1 8 3.00 6.00 4.3
Notes:
. Only chemicals detected at least oncc in thc sourcc area wcn grouping are presented.
o. Method of calculation: (number of samples with detected conccntratioDSInumber of samples within this well grouping)
. MinimumlMaximum detected concentration values (only two figures are significant).
. Geometric mean ofthc median concentrations from all wclls in this well grouping including 1/2 the detection limit for non-detects (only two figures
are significant).
DEN056.XLS
6-31
-------
Table ..3
Summary of Chemical Couceatratioo Data for
Dowogradieat Unweathered Dawson MODitoriug Wells
Outside the Source Area
P82e 1 of 3
Frequency (b)
of MiDimum (e) Maximum (e)
No. of No. of Detects Det.eded Det.eded Average (eI)
Chemical Name (a) Analyses Detects ($) CoaeeatratiOD Coaeeatration Detect
Orgauics (pgII)
1,1,1- TrichloroerhaDe 101 8 8 3.00 77.00 3.30
1,I-Dichloroethane 102 7 7 2.00 35.00 2.72
1,I-Dichloroethylene 102 5 5 1.00 5.00 2.45
1,2,3,4,6,7,8-Heptachlordibenzo-p-Dioxin 14 2 14 0.00001 0.00006 0.000007
1,2,3,4,7,8-Hexachlorodibenzofuran 14 1 7 0.000003 0.000003 0.0000019
1,2,3,6,7,8-HexachlorodibeDzofuran 14 1 7 0.00001 0.00001 0.0000019
1,2,3,7,8,9-HexachlorodibeDZOfuran 14 2 14 0.00001 0.00001 0.000003
1,2-Dichloroetbane 102 6 6 5.00 459.00 3.14
~,3,4,6,7,8-HexachlorodibeDzofuran 14 2 14 0.00001 0.00001 0.000003
~,3, 7,8-TetrachlorodibeDZOfuran 14 1 7 0.00001 0.00001 0.0000019
~,4,5-T 12 1 8 0.30 0.30 0.30
~-Butanone (MEK) 72 3 4 1.10 7.90 4.85
~-Hexanone 102 3 3 1.30 5.00 4.65
!4-Methyl-2-Pentanone (MIBK) 102 2 2 1.60 2.00 4.59
~cetone (2-Propanone) 102 24 24 3.00 140.00 11.31
~DZene 102 1 1 11.00 11.00 2.7
bis(2-EdlylhexyI)Phlhalate 93 8 9 1.00 33.00 4.08
Chloroform 102 4 4 0.30 5.00 2.31
Di-N-Butylphtha1ate 93 3 3 4.00 4.80 4.67
HeptachlorodibeDZOfurans 14 1 7 0.00001 0.00001 0.0000026
HexachlorodibeDZOfurans 15 1 7 0.00001 0.00001 0.0000024
Methylene Chloride 102 13 13 0.90 640.00 2.72
PentachlorodibeDZOfurans (l'otal) 14 1 7 0.00002 0.00002 0.0000034
Phenol 93 2 2 3.40 6.00 5.26
Propoxur 14 1 7 2.00 2.00 0.65
TetrachlorodibeDZOfuran (Dioxin) 14 1 7 0.000004 0.000004 0.0000024
Tetrachloroethylene 102 4 4 1.00 31.00 2.78
Toluene 102 9 9 1.00 3.00 1.96
Total Heptachlorodibenzo-P-Dioxin 14 1 7 0.0001 0.0001 0.0000074
Trichloroethylene 102 2 2 8.00 8.00 2.62
Inorganics (pgII)
Aluminum 89 2S 28 2.40 4900.00 62.31
Antimony 81 6 7 0.61 164.00 11.70
Arsenic 84 9 11 1.75 20.90 1.77
Barium 89 72 81 8.90 545.00 33.19
Beryllium 89 2 2 1.10 1.20 0.68
Boron 33 27 82 26.50 843.00 147.90
Cadmium 89 2 2 2.80 5.60 1.92
Chromium (l'otal) 89 16 18 0.43 34.00 3.22
Cobalt 89 10 11 0.56 4.90 1.51
Copper 89 16 18 1.40 47.00 6.21
iCYanide 80 5 6 10.00 180.00 UO
iFIuoride 31 18 58 140.00 1750.00 352.64
~d 73 13 18 0.88 12.00 1.66
Manganese 89 85 96 1.80 603.00 121.99
Mercury 89 9 10 0.26 2.00 0.19
DENOS7.XLS
6-32
-------
Table 6-3
Summary of Chtmical CODCeDtration Data for
Downgradieat Unweathered Dawsou Monitoring Wells
Outside the Source Area
Pue2 of 3
Frequeocy (b)
of Minimum (c) Maximum (c)
No. of No. or Detects Detected Detected Average (d)
Chemical Name (a) _L Detects ("AI) CODCeotratioD CODCeDtration Detect
INickel 89 17 19 1.40 40.00 6.97
!Selenium 86 13 15 1.90 188.00 2.77
Isilver 83 7 8 3.40 14.00 2.74
lJ'hallium 82 13 16 0.25 1.30 1.18
trm 17 1 6 102.00 102.00 11
lVanadium 89 6 7 1.41 26.00 4.04
Izinc 89 46 52 3.50 200.00 15.57
RadioDuclides (pCiII)
Americium-241 (Alpha) 10 2 20 0.04 200000o.00 10.1
Antimony-l22 29 4 14 0.15 800.00 19
Antimony-l25 29 1 3 4.00 10.00 5.1
Arsenic-76 27 1 4 0.01 800000o.00 1,3OC
Barium-14O 29 1 3 3.50 30.00 8.5
Bismuth-214 35 11 31 3.00 92.00 8.4
Cadmium-I 00 29 1 3 30.00 150.00 54
Cerium.139 29 1 3 1.50 5.00 2.3
Cerium.143 3 3 100 35.00 50.00 41.21
r'erium-l44 35 1 3 10.00 460.00 27
Cesium-134 35 1 3 1.50 60.00 3.7
Cesium-137 35 1 3 1.50 20.30 2.8
Chromium-51 29 1 3 10.00 60.00 20
OOalt-57 29 1 3 1.50 5.00 2.3
Cobalt-60 35 2 6 1.50 17.00 2.8
odiDe-l24 29 1 3 0.50 200.00 2.8
odiDe-131 29 1 3 1.00 30.00 16
odiDe-132 29 1 3 0.25 300.00 15
_L m-14O 29 3 10 1.00 20.00 3.7
1J..ead-212 7 4 57 8.49 25.00 14.38
!Lead-212-Bismuth 28 1 4 2.50 15.90 4.3
!Lead-214 35 11 31 5.00 89.50 13.07
IPIutonium-239 29 6 21 0.03 45.00 0.2
lPotassium.40 35 2 6 25.00 163.00 54
IRadium.226 7 3 43 0.20 30.00 1.2
IRadium-228 29 1 3 5.00 25.00 10
lRubidium.83 29 1 3 2.50 10.00 4.0
iRuthenium-l06 35 1 3 10.00 87.50 23
Scaudium.46 29 1 3 1.50 7.00 2.8
Silver-ll 0 29 1 3 1.50 6.00 2.5
Strontium-90 29 2 7 0.15 1.90 0.43
Thallium-208 35 1 3 4.50 15.00 7.6
Thorium.228 30 . 2 7 2.50 10.00 4.0
Thorium-230 16 5 31 0.05 6.30 0.20
Thorium.232 29 12 41 0.02 17.00 0.30
Thorium-234 29 1 3 25.00 100.00 49
Tritium 30 3 10 15.00 1000.00 50
UI'8Dium-234 21 15 71 0.10 3.80 0.6
Iurauium-235 31 4 13 0.10 40.00 15
DEN057.XLS
6-33
-------
Table 6-3 -
Summary of Che.miI;aI Couceotration Data for
Dowagradieat Unweathered Dawson MoaitoriDg WeDs
Outside the Source Area
Pue 3 or 3
Freqaeacy (b)
of Mmimum (c) Maximum (c)
No. of No. of Detects Detected Detected Average (d)
Chemical Name (a) ... _L - Detects (%) Coaceatratioo CoDCeDtration Detect
Vranium-238 33 12 36 0.02 190.00 03
Uranium-Natural 6 4 67 0.15 2.35 1.00
Yttrium-88 29 2 7 1.50 5.00 2.1
Zinc-65 35 1 3 2.50 27.00 5.4
Notes:
a. Only chemicals detected at least once in the source area wen grouping are presented.
b. Method of calculation: (number of samples with detected concentrations/number of samples within this well grouping)
c. MinimumlMaximum detected concentration values (only two figures are significant).
d. Geometric mean of the median concentrations from all wens in this wen grouping including 1121he detection limit for non-detects (only two figures
are significant).
DEN057.XLS
6-34
-------
Table 6-4
Summary ofn-n;.-"I CoaceatraDon Data for Deep Ground-Water MonitoriDg WeDs
Pa2e 1 of 2
Frequeacy (b)
of Minimum (c) Maximum (c)
No. of No. of Detects Detected Detected Average (d)
Chemical Name (a) ".._L - Detects (%) COOCeutratiOD Concentration Detect
Orgaoics (pgII)
1,1,1- TrichloroelbaDc 44 11 25 3.00 23000.00 4.76
1,1,2-TrichloroelbaDc 44 1 2 2.00 2.00 2.4
1,I-DichloroelbaDc 44 10 23 86.00 1900.00 4.43
1,I-Dichloroelhylene 44 9 20 54.00 560.00 4.26
1,2,3,4,6,7,8-Heptachlorodibcnzofuran 5 1 20 0.00008 0.00008 0.000011
1,2,3,4,7,8-Hexacblorodibcnzofuran 5 1 20 0.00003 0.00003 0.0000061
1,2,3,6,7,8-Hexachlorodibcnzofuran 5 1 20 0.00002 0.00002 0.0000049
1,2-Dicbloroelhene (Total) 45 1 2 7.00 7.00 2.8
1,2-Dichloropropane 44 1 2 2.00 2.00 2.4
,3,4,6,7,8-Hexacblorodibcnzofuran 5 1 20 0.00002 0.00002 0.0000053
~Methyl-2-Pentanone (MIBK) 44 3 7 10.00 600.00 5.51
Acetone (2-Propanone) 44 9 20 5.30 1100.00 16.68
Aluminum 37 15 41 7.29 30100.00 116.49
Benzene 44 3 7 2.00 47.00 3.48
is(2-Ethylhexyl)Phtha1ate 34 6 18 3.00 30.00 6.35
Boron 12 11 92 39.10 602.00 157.60
Carbon Disulfide 44 1 2 24.00 24.00 3.2
Chloroform 44 1 2 2.00 2.00 2.4
Di-N-Butylphthalate 34 3 9 2.40 6.00 4.70
Di-N-<>Ctylphthalate 34 1 3 18.00 18.00 6.2
Elhylbenzene 44 1 2 22.00 22.00 3.2
fleptacblorodihenzofurans 5 1 20 0.000110 0.000110 0.000014
flexachlorodihenzodioxins 5 1 20 0.000005 0.000005 0.0000042
flexachlorodibcnzofurans 5 1 20 0.000090 0.000090 0.0000088
37 29 78 1.80 9100.00 34.50
!Methoxychlor 30 1 3 0.11 0.11 0.19
!Methylene Chloride 44 6 14 2.90 13000.00 3.53
!Naphthalene 34 1 3 2.80 2.80 4.7
joctachlorodibcnzodioxiDs (Total) 5 2 40 0.00004 0.00010 0.00005
I<>ctacblorodibcnzofurans (Total) 5 1 20 0.00008 0.00008 0.000035
lPeDlachlorodibcnzofurans (Total) 5 1 20 0.00003 0.00003 0.0000048
jPhenol 34 1 3 2.40 2.40 5.0
trell'achlorodibcnzofuran (Dioxin) 5 1 20 0.00003 0.00003 0.0000028
trell'achloroethylene 44 11 25 2.90 5000.00 5.01
troluene 44 12 27 1.80 1200.00 5.17
trotal Heptachlorodibcnzo-P-Dioxin 5 1 20 0.00002 0.00002 0.000014
trotal Xylenes 44 8 18 15.00 750.00 3.94
Trichloroethylene 44 4 9 9.00 290.00 3.65
lnorg&Dics (pgII)
Arsenic 33 4 12 1.70 30.00 1.93
Barium 37 32 86 28.00 1050.00 61.28
Beryllium 37 1 3 1.20 1.20 0.96
Chromium (Total) 37 5 14 0.48 60.00 3.89
Cobalt 37 2 5 7.30 35.00 7.75
Copper 37 4 11 7.40 72.00 6.36
!Cyanide 36 1 3 25.70 25.70 5.8
lFIuoride 17 14 82 350.00 970.00 631.30
DEN058Ja.s
6-35
-------
I Table 6-4 ~2~']
Summary ofCbemical Couceotratiou Data for Deep Gromad-Water Moaitoriog WeDs
Frequeacy (b) Maximmn (c)
of Minimum (c) I
No. of No. of Detects Detected Detected Average (d)
CbemicaI Name (a) AnaIvses Detects (%) CoDCeDtration ConceDtration Detect
Lead 32 6 19 1.10 26.00 1.75
Mercury 37 4 11 0.13 1.70 0.20
Nickel 37 3 8 2.20 162.00 13.81
Selenium 30 2 7 1.80 2.90 1.36
Thallium 31 2 6 0.33 0.91 1.38
Vanadium 37 5 14 1.90 90.00 5.41
7inc 37 22 59 3.80 275.00 17.13
RadioDuc~ (pCiIl)
Americium-241 10 2 20 0.31 1500000.00 160.69
Americium-241 (Alpha) 5 1 20 0.21 1500000.00 140
Arsenic-76 8 1 13 4.50 3500000.00 180
Barium-133 10 1 10 1.50 5.00 2.3
Bismuth-214 14 9 64 4.50 141.00 21.74
Cadmium-l09 12 2 17 40.00 430.00 64.45
lcerium-143 2 2 100 18.00 51.00 30.30
1Jron-59 14 1 7 3.00 26.75 6.6
ILead-212 6 3 50 3.25 31.00 11.11
ILead-212-Bismuth 8 1 13 3.50 6.00 4.3
ILead-214 14 8 57 5.00 148.00 28.13
~eodynium-147 10 1 10 15.00 100.00 36
PIutonium-239 12 3 25 0.03 0.60 0.1 ~
Radium-226 4 4 100 0.60 0.80 0.71 ~
"
Rubidium-83 10 1 10 3.00 6.00 4.1
Thallium-208 14 1 7 4.85 17.00 6.6:
Thorium-22S 12 1 8 0.25 4.50 2.5
Thorium-230 8 5 63 0.04 16.00 0.80
Thorium-232 12 3 25 0.03 1.70 0.22
~1D-1l3 10 1 10 1.50 3.00 I.9,
Iuranium-234 8 4 50 0.10 2.20 0.38
Iuranium-235 12 2 17 8.30 20.00 16.30
Iuranium-238 12 5 42 0.03 23.50 0.25
Uranium-Natural 4 1 25 0.10 1.50 0.7
1!..eoon-131M 10 2 20 75.00 400.00 166.32
7irconium-89 10 1 10 2.00 500.00 17
NOleS:
. Only chemicals detected at least once in the source area well grouping are presented.
~. Method of calculation: (number of samples with detected concentrations/number of samples within this well grouping)
. MinimumIMaximum detected concentration values (only two figures are significant).
d. Geometric mean of the median concemratioDS from all wells in this well grouping including 1/2 the detection limit for non-detects (only two figures
are significant.)
DEN058.XLS
6-36
-------
Table ()'5
Sammary of CheIIIicaI CODCeDtratioD. Data for Upgradieat MODitoriDg We& Outside of the Source Area
P82e 1 of 2
Frequmcy (b)
of Minimum (c) Maximum (c)
No. of No. of Detects Detected Detected Average (d)
Chemical Name (a) Detects ('Ii) Couceotration CODCeutrabon Detect
Organics (pgII)
1,1 , I-Trichloroethane 33 4 12 4.00 5.00 3.33
1,I-Dichloroethylene 33 1 3 1.00 1.00 2.10
,3,4,6,7,8-Hexachlorodibenzofuran 4 1 25 0.000004 0.000004 0.0000045
-Butanone (MEK) 24 1 4 7.50 7.50 5.30
!4-Methyl-2-Pentanone (MIBK) 33 1 3 14.00 14.00 5.90
iAcetone (2-Propanone) 33 7 21 1.00 13.00 6.96
Beuzoic Acid 26 1 4 4.60 4.60 21.00
. bis(2-Ethylhe)C)'I)Phthalate 28 2 7 8.00 84.00 8.65
Di-N-Butylphthalate 28 3 11 3.60 14.00 6.70
Di-N-<>Ctylphthalate 28 1 4 8.00 8.00 61.00
exachlorodibenzofurans 4 1 25 0.000004 0.000004 0.0000045
; N ethylene Chloride 33 11 33 1.60 24.00 7.68
. Ictachlorodibenzodioxins (Total) 4 1 25 0.00012 0.00012 0.00004
! Octachlorodibenzofurans (Total) 4 1 25 0.00002 0.00002 0.000013
Phenol 28 2 7 2.20 2.20 4.27
Tetrachloroethylene 33 5 15 1.60 6.00 2.98
;Toluene 33 6 18 1.10 4.00 2.20
,Trichloroethylene 33 1 3 1.00 1.00 2.10
! lnorganics (pgJI)
.Aluminum 46 19 41 15.13 24600.00 176.41
.Amimony 45 6 13 3.07 770.00 4.15
.!\rsenic 42 8 19 1.10 6.00 8.64
8ariwn 46 27 59 8.01 188.00 22.36
Ikryllium 45 3 7 0.30 1.10 0.67
iknon 13 5 38 14.40 210.00 107.36
i::admium 46 2 4 2.20 3.40 2.08
:hromium (Total) 46 6 13 3.40 210.00 6.17
:obalt 46 6 13 2.10 27.90 1.85
=opper 46 10 22 3.90 90.90 10.87
Cyanide 41 1 2 5.00 5.00 3.00
iluoride 2 1 50 670.00 670.00 230.00
.ad 42 4 10 4.00 34.60 1.90
,w.ganese 46 38 83 5.90 958.00 28.39
,fercury 46 4 9 0.31 1.00 0.29
1ickel 46 6 13 20.50 61.00 15.90
elenium 38 25 66 1.30 372.00 36.10
.ilver 46 2 4 3.30 3.50 2.19
ranadium 46 5 11 1.30 65.00 9.18
;me 46 27 59 3.60 655000.00 66.37
Radionudides (pCi/l)
Unerlcium-241 (Alpha) 2 1 50 0.10 1.30 0.40
:isnwtb-214 15 5 33 3.50 74.00 8.42
ead-212 4 1 25 2.75 30.00 9.30
ead-214 15 3 20 5.00 55.00 12.60
lutonium-239 4 1 25 0.05 0.59 0.10
otassium-40 5 1 20 25.00 200.00 52.00
adium-226 3 1 33 0.50 50.00 11.00
horium-232 4 2 50 0.02 12.00 0.34
DEN060JeLS
6-37
-------
Summary of Chemical Coaceatratioa Data for Upgradieat MoaitoriDg Wells Outside of the Soun:e Area Pue2 of 2
Freqaeacy (h)
of MiDimDlD (c) MaximDlD (e)
No. of No. of Detects Detected Detected Avenge (d)
ChemicaI Name (a) _L Detects (CJf,) COJICeatraDon CoJICeotration Detect
Uranium-234 2 2 100 0.60 2.20 1.15
Uranium-235 5 1 20 12.50 20.00 16.00
Iuranium-238 4 2 50 0.04 5.20 0.74
IUranium-NalUral 2 1 50 1.50 19.00 5.30
!Notes:
ja. Ouly chemicals detected at least ouce in the source area well grouping are presented.
~. Method of calculation: (number of samples with detected conceDlrationslnumber of samples within this well grouping)
Ie. MinimumIMaxinwm detected c:oncenIration values (only two figures are significant).
lei. Geometric mean of the median COncentratiODS from all wells in this well grouping including 1/2 the detection limit for non-detects (only two figures are signifiCUlt).
DEN060.xz.s
6-38
-------
9'
~
\0
Table 6-6
Summary of Chemicals Detected in Unsaturated Solids Within the Landfill Mass Page 1 of S
Frequency of
Parameter Name No. of Analyses No. or Detects Minimum Detect Maximum Detect Average Detect Detects (%)
Organics (pg/kg)
1,l-Dichloroethane 19 2 8 950 480 11
1,1,1- Trichloroethane 19 2 2 24,000 12,000 11
1,2-Dichlorobenzene 18 1 800 800 800 5.6
t ,2-Dichloroethane 19 6 3 510 220 32
1,2,4- Trichlorobenzene 18 1 11,000 11,000 11,000 5.6
1,3-Dichlorobenzene 18 1 1,300 1,300 1,300 5.6
1,4-Dichlorobenzene 18 3 540 1,900 1,300 17
2-Butanone (MEK) 18 10 6.0 3,100 610 56
2-Hexanone 19 1 85 85 85 5.3
2-Methylnaphthalene 18 6 290 5,900 2,500 33
2-Methylphenol 18 1 2,000 2,000 2,000 5.6
4-Chloroaniline 18 1 680 680 680 5.6
4-Methylphenol 18 5 180 8,000 3,100 28
4-Methyl-2-pentanone (MIBK) 19 4 25 330 120 21
4,4'-DDD 19 5 1.9 400 150 26
4,4'-DDE 19 9 0.52 87 22 47
4,4'-DDT 19 6 1.1 1,700 290 32
Acenaphthene 18 1 220 220 220 5.6
Acetone (2-propanone) 19 11 no 8,200 1,700 58
Aldrin 19 4 1.1 3.2 1.7 21
Alpha Chlordane 19 6 1.9 390 11 32
AIpha-BHC 19 2 1.3 2.0 1.7 11
Benzene 19 4 2.0 16 8.0 21
Beta-BHC 19 3 4.1 17 9.2 16
DENlOO14EB3.WPS
-------
~
Table 6-6
Swnmary of Chemicals Detected in Unsaturated Solids Within the Landfill Mass Page 2 of S
Frequency of
Parameter Name No. of Analyses No. of Detects Minimwn Detect Maximum Detect Average Detect Detects (%)
Organics (pg/kg) (Continued)
Bis(2-ethylhexyl)phthalate 17 13 640 52,000 18,100 76
Butylbenzylphthalate 18 10 190 37,000 9,700 56
Carbon disulfide 19 1 2.0 2.0 2.0 5.3
Chlorobenzene 19 1 2.0 2.0 2.0 5.3
Chloroform 19 3 3.0 300 110 16
Delta-BHC 19 2 0.50 14 7.3 11
Dibenzofuran 18 1 140 140 140 5.6
Dieldrin 19 8 0.50 21 4.9 42
Diethylphthalate 18 7 100 8,200 2,200 39
Dimethylphthalate 18 1 510 510 510 5.6
Di-n-butylphthalate 18 12 280 19,000 4,700 67
Di-n-octylphlhalate 18 4 450 9,000 6,100 22
Endosulfan sulfate 19 6 0.19 640 110 32
Endosulfan II 19 5 0.25 790 160 26
Endosulfan I 19 5 0.36 6.2 2.5 26
Endrin ketone 19 4 0.90 95 28 21
Endrin 19 9 0.49 38 9.6 47
Endrin aldehyde 17 8 0.44 370 52 46
Ethylbenzene 19 12 4.0 5,300 580 63
Fluoranthene 18 1 500 500 500 5.6
Gamma chlordane 19 8 0.57 18 5.3 42
Gamma-BHC (Lindane) 19 3 1.5 13 5.7 16
Heptachlor 19 4 0.60 10 3.3 21
DEN1OO14EB3.WPS
-------
t
~
Table 6-6
Summary of Chemicals Detected in Unsaturated Solids Within the Landfill Mass Page 3 of 5
Frequency of
Parameter Name No. of Analyses No. of Detects Minimum Detect Maximum Detect Average Detect Detects (%)
Organia (1IK/kg) (Continued)
Methoxychlor 19 5 0.41 36 14 26
Methylene chloride 18 12 13 13,000 1,300 67
N -nitroso-di-n-propylamine 18 1 23,000 23,000 23,000 5.6
N-nitrosodiphenylamine 18 3 800 1,500 1,100 17
Naphthalene 18 6 76 3,100 1,200 33
PCB-1260 (Aroclor 1260) 19 2 230 54,000 27,000 11
Pentachlorophenol 18 3 480 3,200 2,200 17
Phenanthrene 18 3 450 1,300 910 17
Phenol 18 11 120 7,000 2,400 61
Pyrene 18 1 560 560 560 5.7
Styrene 19 6 3.0 120 52 32
Tetrachloroethylene 19 9 6.0 4,800 650 47
Toluene 19 14 5.0 530,000 43,000 74
Total xylenes 19 14 7.0 61,000 8,500 74
Trichloroethylene 19 5 8.0 3,000 690 26
Inorganics (mg/kg)
Aluminum 17 14 118 25,000 6,200 82
Arsenic 18 10 1.4 7.3 3.8 56
Barium 17 14 6.8 355 120 82
Beryllium 18 9 0.31 1.1 0.59 50
Cadmium 18 3 1.2 15.3 6.3 17
Chromium (Total) 17 13 2.7 46.7 17 76
Cobalt 18 10 4.3 10 6.9 56
Copper 17 14 3.6 2,500 230 82
DEN1OO14EB3.WP5
-------
~
Table 6-6
Swiunary of Chemicals Detected in Unsaturated Solids Within the Landfill Mass Page 4 of.!
Frequency of
Parameter Name No. of Analyses No. of Detects Minimum Detect Maximum Detect Average Detect Detects (%)
Inorganics (mg/kg) (Continued)
Fluorene 18 1 260 260 260 5.6
Lead 17 14 0.77 1,400 150 82
Manganese 17 14 51 940 420 82
Mercury 18 5 0.22 0.87 0.49 28
Nickel 18 11 4.1 45 16 61
Selenium 18 1 1.6 1.6 1.6 5.6
Silver 18 1 4.1 4.1 4.1 5.6
Vanadium 17 11 5.2 65 19 64
Zinc 17 14 18 3,800 540 82
Radionudides - pCi/g
Alpha (Gross) 13 10 0 34 13 77
Americium-241 (Alpha) 13 10 0 1.6 0.20 77
Beta (Gross) 13 10 0.18 43 20 77
Bismuth-214 13 6 0.97 3.4 1.5 46
Iodine-131 13 10 0 42 8.1 77
Iron-59 13 2 0.34 10 5.2 15
Lead-21 0 13 10 0.18 2.1 1.2 77
Lead-214 11 5 0.92 1.2 1.1 45
Phosphorus-32 13 1 5.0 5.0 5.0 7.7
Plutonium-239 13 10 0 2.0 0.33 77
Potassium-40 13 7 11 26 19 54
Radium-226 13 10 0.01 2.4 0.98 77
Radium-228 13 10 0 2.0 0.94 77
Strontium-90 13 10 0 0.30 0.13 77
DEN10014EB3:WP5
-------
Table 6-'
Summary of Chemicals Detected in Unsaturated Solids Within the Landfill Mass Page 5 of 5
Frequency of
Parameter Name No. of Analyses No. of Detects Minimwn Detect Maxbnwn Detect Average Detect Detects (~)
Radionuclides-pCi/g (Continued)
Thorium-228 13 10 0 2.2 0.67 77
Thorium-232 13 10 0 1.4 0.65 77
Uranium-234 13 10 0 1.9 0.91 77
Uranium-235 13 10 0 0.1 0.01 77
Uranium-238 13 10 0 1.5 0.64 77
Source: CDM, 1993.
t
t.U
DENl0014EB3.WP5
-------
0\
I
t
Table 6-7
Summary of Chemicals Detected in Unsaturated Solids
Within the Fonner Tire Pile Area Page 1 of S
Frequency of Minimum Maximum
Parameter Name No. of Analyses No. of Detects Detects Detect Detect Average Detect
Organics ("g/kg)
1, I-Dichlorethane 15 1 6.7 1,200 1,200 1,200 .
1,1,1- Trichlorethane 15 2 13 3.9 1,700 840
1,1,2,2- Tetrachlorethane 9 1 11 5,000 5,000 5,000
1,2-Dichlorethane 15 I 6.7 3,900 3,900 3,900
1,2-Dichlorethene (total) 13 2 15 3,900 34,000 19,000
1,2-Dichloropropane 15 1 6.7 11,000 11,000 11,000
1,2,3,4,6,7,8-Heptachlordibenzo-p-dioxin 3 3 100 0.68 1.3 1.0
1,2,3,4,6,7,8-HeptachlordibenzofUran 3 3 100 0.13 0.28 0.18
1,2,3,4,7,8-HexachlordibenzofUran 3 3 100 0.0060 0.12 0.045
1,2,3,4,7,8-Hexachlorodibenzo-p-dioxin 3 1 33 0.0080 0.0080 0.0080
1,2,3,4,7,8,9- Heptachlordibenzo-p-dioxin 3 2 67 0.0030 0.020 0.012
1,2,3,4,7,8,9-HeptachlorodibenzofUran 3 3 100 0.0020 0.28 0.12
1,2,3,6,7,8-Hexachlorodibenzo-p-dioxin 3 3 100 0.030 0.070 0.040
1,2,3,6,7,8-HexachlorodibenzofUran 3 3 100 0.0020 0.050 0.020
1,2,3,7,8-Pentachlorodibenzo-p-dioxin 3 1 33 0.0050 0.0050 0.0050
1,2,3,7,8-Pentachlorodibenzofuran 3 3 100 0.0010 0.15 0.057
1,2,3,7,8,9-Hexachlorodibenzofuran 3 1 33 0.040 0.040 0.040
2-Butanone (MEK) 11 1 9.1 2,200 2,200 2,200
2-Hexanone 15 1 6.7 6,900 6,900 6,900
2-Methylnaphthalene 15 2 13 11,000 70,000 40,000
2,3,4,6,7,8-lIexachlordibenzofuran 3 1 33 0.020 0.020 0.02
2,3,4,7,8-Pentachlorodibenzofuran 3 3 100 0.0040 0.060 0.02
2,3,7,8-Tetrachlordibenzofuran 3 3 100 0.0080 0.17 0.066
DEN10014EB4.WPS
-------
x
U1
Table 6-7
Summary of Chemicals Detected in Unsaturated Solids
Within the Fonner Tire Pile Area Page 2 of S
Frequency of Minimum Maximum
Parameter Name No. of Analyses No. of Detects Detects Detect Detect Average Detect
Organics (ltg/kg) (Continued)
3,3' -Dichlorobenzidine 14 1 7.1 420 420 420
4-Methyl-2-pentanone (MIBK) 15 3 20 2.7 54,000 22,000
4,4'-DDE 15 3 20 96 25,000 9,000
4,4'-DDT 15 2 13 30 63 47
Acetone (2-propanone) 15 6 40 24 360,000 78,000
Aldrin 15 2 13 3.7 55 29
Alpha chlordane 13 1 7.7 0.16 0.16 0.16
Benzene 15 3 20 1.0 5,500 2,600
Beta-BHC 15 1 6.7 6.0 6.0 6.0
Bis(2-ethylhexyl)phthalate 15 8 53 49 35,000 9,100
Butylbenzylphthalate 14 1 7.1 48 48 48
Chlorobenzene 15 2 13 2,800 16,000 9,300
Delta-BHC 15 1 6.7 8.0 8.0 8.0
Di-n-octylphthalate 14 1 7.1 43 43 43
Dieldrin 15 I 6.7 9.5 9.5 9.5
Ethylbenzene 15 3 20 900 170,000 80,000
Gamma chlordane 13 1 7.7 51 51 51
Heptachlor 15 1 6.7 83 83 83
Heptachlorodibenzofurans 3 3 100 0.74 1.3 0.94
Hexachlorodibenzofurans 3 3 100 0.12 0.44 0.23
HXCDD (Dioxin) 3 3 100 0.08 0.43 0.20
Methoxychlor 15 1 6.7 0.61 0.61 0.61
DENlOO14EB4.WP5
-------
~
Table 6.7
Summary of Chemicals Detected in Unsaturated Solids
Within the Former Tire Pile Area Page 3 of S
Frequency of Minimwn Maximwn
Parameter Name No. of Analyses No. or Deteds Detects Detect Detect Average Detect
Organics (,.g/kg) (Continued)
Methylene chloride 15 2 13 7.0 9,600 4,800 .
Naphthalene 14 1 7.1 8,600 8,600 8,000
Octachlorodibenzodioxins (Total) 3 3 100 5.6 12 9.0
Octachlorodibenzofurans (Total) 3 3 100 1.10 2.1 1.5
PCB-I016 (Arc1or 1016) 15 1 6.7 950 950 950
PCB-1254 (Aroclor 1254) 15 1 6.7 1,000 1,000 1,000
Pentachlorodibenzodioxins (Total) 3 2 67 0.0010 0.0040 0.0030
Pentachlorodibenzofurans (Total) 3 3 100 0.010 0.83 0.30
Phenanthrene 15 3 20 43 17,000 6,600
Phenol 15 1 6.7 47,000 47,000 47,000
Tetrachlorethylene 15 3 20 1.9 83,000 28,000
Tetrachlorodibenzofuran (dioxin) 3 3 100 0.020 1.0 0.38
Toluene 15 3 13 120,000 790,000 460,000
Total Heptachlorodibenzo-p-dioxin 3 3 100 1.9 2.1 2.0
Total Xylenes 15 3 20 2,600 2,500,000 1,000,000
Trichlorethylene 15 2 13 11,000 41,000 26,000
Inorganics (mg/kg)
Aluminum 16 13 81 9,200 21,000 15,000
Antimony 8 2 25 1.0 30 16
Arsenic 13 8 62 0.86 18 7.3
Barium 16 16 100 24 1,200 270
Beryllium 16 14 88 0.10 2.1 1.1
Boron 3 2 67 9.8 10 7.4
DEN 100 14EB4.WPS
-------
;
Table 6-7
Summary of Chemicals Detected in Unsaturated Solids
Within the Fonner Tire Pile Area Page 4 of S
Frequency of Minimum Maximum
Parameter Name No. of Analyses No. of Detects Detects Detect Detect Average Detect
Inorganics (mg/kg) (Continued)
Cadmium 16 9 56 0.09 3.3 1.4
Chromium (Total) 16 16 100 6.6 240 32
Cobalt 16 16 100 4.1 15 8.7
Copper 16 16 100 13 40 22
Cyanide 13 2 15 0.94 1.6 1.3
Lead 16 15 94 8.3 250 35
Manganese 13 10 77 120 1,100 560
Mercury 16 4 25 0.070 20 5.0
Nickel 16 14 88 9.0 40 13
Silver 16 2 13 0.253 16 8.1
Thallium 16 3 19 0.030 0.22 0.15
Vanadium 16 16 100 12 170 44
Zinc 16 16 100 40 110 65
Radionuclides - pCi/g
Actinium-228 3 3 100 0.77 NR 1.1
Alpha (Gross) 9 8 89 9.4 29 18
Americium-241 (Alpha) 9 6 67 0 1.5 0.27
Beta (Gross) 9 9 100 9.8 64 37
Bismuth-214 9 5 56 0.69 2.7 1.5
Fluorene 15 1 6.7 22,000 22,000 22,000
Iodine-131 8 5 63 0 1.0 0.20
Lead-210 6 4 67 1.2 1.8 1.6
Lead-212-bismuth 3 1 33 0.27 0.27 0.27
-------
~
Table 6-7
Summary of Chemicals Detected in Unsaturated Solids
Within the Fonner Tire Pile Area Page 5 of 5
Frequency of Minimum Maximum
Parameter Name No. of Analyses No. of Deteds Detects Detect Detect Average Detect
Radionuciides-pCi/g (Continued)
Lead-214 9 9 100 0.33 2.9 1.4
Plutonium-239 9 8 89 0 0.40 0.12
Potassium-40 9 9 100 4.8 36 22
Radium-228 (Beta) 3 3 100 0.26 1.3 0.92
Radium-226 6 6 100 1.2 2.9 1.8
Radium-228 9 9 100 0.2 3.0 1.4
Strontium-90 9 6 67 0 0.20 0.030
Thallium-208 3 3 100 0.40 1.2 0.85
Thorium-228 9 9 100 0.27 2.2 1.4
Thorium-230 6 6 100 1.2 2.1 1.6
Thorium-232 9 9 100 0.15 1.7 1.1
Tritium 3 1 33 0.27 0.27 0.27
Uranium-234 9 9 100 0.12 2.9 1.1
Uranium-235 (Alpha) 3 1 33 0.05 0.053 0.050
Uranium-235 9 6 67 0 0.10 0.020
Uranium-238 9 9 100 0.07 I.S 0.89
NR = Not reported.
DEN10014EB4.'NPS
-------
Table 6-8
MdhaDe ConCOlltratioll8 in Perimeter G... Monitoring Wells
Methouae CoDCOlltrations ("Ii by Volume)"
G... Probe 8/91 9/91 10/91 11/91 11/91 1/92 2/92 3/92 4/92 5/92 6/92 7/92 8/92
GMP-l 0 NR 0 0 - 0 0 0.8 0 0 0 0 0
GMP-2 0 0 0 0 - 0 0 0 0 0 0 0 0
GMP-3 0.6 5 0 0.9 - 1.0 0 6 0.8 1.8 7 2.2 55
GMP-4A 0 0 0 0 - 0 0 0 0 0 0 0 0
GMP-5A 0 0 0 0 - 0 0 0 0 0 0 0 0
GMP-6A 30 4 0 0 - 1.5 44 SO 47 45 36 38 49
GMP-7 10 16 0.3 10 - 19 7.5 30 16 25 16 13 22
GMP-8 0 0 0 0 - 0 0 0 0 0 0.4 0 0
GMP-9 0.7 30 0 1.6 - 25 0.2 0.2 1.1 0.3 0.2 0.1 0
GMP-I0 0 0 0 0 - 0 0 0 0 0 0 0 0
GMP-ll 0 NR 0 0 - 0 0 0 0 0 0 0 0
GMP.12 0 NR 0 0 - 0 0 0 0 0 0 0 0
GMP-13 0 NR 0 0 - 0 0 0 0 0 0 0 0
GMP-I09 0 NR NR 0 - 0 0 0 0 0 0 0 0
GMP-ll0 0 NR NR 0 - 0 0 0 0 0 0 0 0
MdbaDe CoDCOIItratioDB ("Ii by Volume)"
G- Probe 9/92 10/92 11/92 12/92 1/93 2/93 3/93 4/93 5/93 6/93 7/93 8193 9/93
GMP-l 0 0 0 0 0 0 0.8 0 0 0 0 0 0
GMP-2 0 0 0 0 0 0.2 0 0 0 0 0 0 0
GMP-3 0.8 0.8 0.8 0 0 0.2 0 1.0 0.2 2.6 0.7 0.1 0
GMP-4A 0 0 0 0 0 0 0 0 0 0 0 0 0
GMP-5A 0 0 0 0 0 0 0 0 0 0 0 0 0
GMP-6A 15 30 30 1.8 0.3 3 0.2 45 24 35 1 35 32
GMP-7 1.7 20 15 7 14 0.2 10 0 4.4 30 10 25 0
GMP-8 0 0 0 0 0 0.2 0 0 0 0 0 0 1.3
GMP-9 6 0 0 0 0 0.2 0.1 14 0.6 20 2.5 0.1 0
GMP-10 0 0 0 0 0 0 0 0 0 0 0 0 0
GMP-ll 0 0 0 0 0 0.1 0 0 0 0 0 0 0
GMP-12 0 0 0 0 0 0 0 0 0 0 0 0 0
GMP-13 0 0 0 0 0 0 0 0 0 0 0 0 0
GMP-I09 0 0 0 0 0 0 0 0 0 0 0 0 0
GMP-ll0 0 0 0 0 0 0 0 0 0 0 0 0 0
"Re8diap IIIka1 wilh . direct reading iDstrumaIt.
Note:
NR = No reading 18kCD.
- = No data c:oUec:ttd.
DENlOOlS3AF.WPS
6-49
-------
I Table 6-9 !
LandfiD Gas Data Summary
MiDimum Maximum
Total Detection Detectioa Reported
Parameter Name Observation Frequeacy (,IgIm3) (pgJaf)
1,1 , I-Trichloroethane 58 60 38 270,000
1,1 ,2-TrichloroethaDe 59 2.0 300 300
1,l-Dichloroethane 59 59 300 770,000
1, l-Dichloroethylene 38 50 170 18,000
1 ,2-Dichloroethaue 38 16 110 68,000
1 ,2-Dichloroethylene (I'otal) 21 43 75 61,000
1 ,2-Dichloropropane 59 5.0 1,000 12,000
2-ButaDOne 62 24 1.0 38,000
4-Methyl-2-PeDfanOne 62 5.0 2,000 49,000
Acetone 61 41 43 85,000
BeDzene 61 57 10 190,000
Bromomethane 59 3.0 62 230
CaJbon disulfide 59 44 22 160,000
CaJbon tetrachloride 62 2.0 86 86
Chlorobeozene 59 5.0 170 3,000
Chloroethaue 59 56 21 780,000
Chloroform 59 20 19 4,000
Chloromethane 59 2.0 4,000 4,000
Elhylbeozene 61 56 30 80,000
Methylene chloride 62 63 42 840,000
Styrene 59 3.0 150 19,000
Tetrachloroethylene 59 64 14 160,000
Toluene 61 79 19 1,400,000
Total Xylenes 60 58 17 120,000
Trans-I ,2-dichloroethylene 38 55 71 110,000
Trichloroethylene 59 53 64 24,000
V"myl Acetate 62 2.0 98,000 98,000
V"myl Chloride 58 57 77 680,000
cis-I ,2-Dichloroethylene 21 33 300 670,000
DENl001527B.WPS
6-50
-------
Table 6-10
Sewage Sludge ApplicationlLeacbate Injection Area (Group 1) Soils Data Summary
Pa2e 1 of2
Detection Minimum Maximum Calculated (a)
Total Frequency Detected Reported Mean
Constituent Observation (%) " -
Ol"2anics
1, 1, I-Trichloroethane 15 20 0.5 3.0 0.9
2-Butanone 2 100 1.0 1.0 1.0
4,4'-DDE 11 9 0.90 3.7 1.2
4-Chloroaniline 27 48 44 2,000 380
4-Nitropbenol 1 100 530 530 530
Acetone 18 17 5.0 140 30
Benzene 29 10 0.50 16 2.7
Benzo(a)pyrene 1 100 52 52 52
Benzo(b )fluoranthene 3 100 33 120 75
Benzo(k)fluoranthene 1 100 72 72 72
aenzoic acid 2 100 60 76 68
beta-BHC 15 20 0.90 5.1 1.7
~ezno(g,b,i)perylene 1 100 64 64 64
~is(2-ethylbexyl)pbthalate 30 67 35 2,200 380
ButvIbenzvlpbthalate 12 17 100 390 200
CaIbon disulfide 18 17 2.5 25 5.0
Chloroform 21 29 0.50 2.0 0.80
Chrysene 1 100 110 110 110
IIdi-n-Butylphthalate 8 88 27 110 60
Dieldrin 15 13 1.6 12 2.9
Fluoranthene 3 67 25 98 58
-Chlordane 11 9 1.6 6.6 2
[eptachlor 14 7 1.5 3.6 1.7
eptachlor epoxide 3 33 1.6 3.2 2.1
I- eptachlorodibenzodioxins 2 50 0.020 1.1 0.60
eptachlorodibenzofurans (Total) 2 50 0.010 0.16 0.090
HexachlorodibeDZOdioxins (Total) 2 50 0.010 0.030 0.020
Hexachlorodibenzofurans (Total) 2 50 0.010 0.020 0.010
Indeno( 1,2,3-a1)pyrene 1 100 52 52 52
Methylene chloride 30 67 1.3 150 35
Octachlorodibenzodioxins (Total) 2 100 0.490 7.2 3.9
K>ctachlorodibenzofurans (Total) 2 50 0.010 0.090 0.050
PCB-126O 24 33 30 7600 520
PentachlorodibeDZOdioxins 2 50 0.010 0.050 0.030
Pentachlorophenol 1 100 150 150 150
Phenanthrene 1 100 41 41 41
Phenol 3 67 39 80 57
Pyrene 4 75 25 91 55
Toluene 29 21 0.50 11 2.3
Inorganics
Aluminum 16 100 13,000,000 17,000,000 15,000,000
Arsenic 16 100 5,600 14,000 8,100
lJ3arium 16 100 210,000 1,200,000 400,000
!Beryllium 16 75 500 13,000 1,700
Cadmium 16 100 1,900 13,000 3,900
DEN061.XLS
6-51
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Table 6-10
Sewage Sludge ApplicationlLeachate Injection Area (Group 1) Soils Data Summary
Paee 2 of2
Detection Minimum I Maximum Calculated (a)
Total Frequency Detected Reported Mean
Constituent Obsen'ation (<
-------
Table 6-11
Sewaj e SIud2e Application Area (Group 2) Soils Data Summarv
Detection Minimum Maximum Calculated (a)
Total Frequency Detected Reported Mean
Constituent Observation (%) - - -
Or!!anics
,4'-DDD 8 13 2.2 38 12
4-Chloroaniline 8 63 55 520 200
Benzoic acid 1 100 210 210 210
bis(2-ethylhexyl)phthalate 8 63 93 510 240
Chloroform 3 33 0.50 3.0 1.3
di-n...()ctylphthalate 1 100 190 190 190
Methylene chloride 8 25 1.7 30 15
!Phenol 2 100 61 76 69
Toluene 8 13 0.5 3.0 2.3
InOl"2anics
Aluminum 6 100 11,000,000 20,000,000 16,000,000
~nic 6 83 1,300 7,300 5,100
aarlum 6 100 140,000 240,000 210,000
!Beryllium 6 83 550 1,500 1,100
Cadmium 6 100 1,400 3,000 2,300
Chromium (total) 6 100 23,000 62,000 45,000
Cobalt 6 100 8,800 12,000 10,000
Copper 6 100 33,000 83,000 60,000
Cyanide 6 33 300 1,800 650
:ad 6 100 44,000 81,000 63,000
ese 6 100 400,000 2,700,000 830,000
ercury 6 50 50 500 225
Nickel 6 100 22,000 30,000 26,000
Vanadium 6 100 31,000 39,000 36,000
~inc 6 100 77,000 160,000 120,000
ja. Arithmetic mean using one-baIf the detection limit for non-detects. I
6-53
DEN062.XLS
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Table 6-12
Leachate Spravin2 Area (Group 3) Soils Data Summary
Detection Minimum Maximum Calculated (a)
'
Total Frequency Detected Reported Mean
Obsenration (%) , -
Constituent
Ol1!anics
Benzene 7 14 0.5 3.0 2.4
l>is(2-ethylhexyl)phthalate 7 14 46 215 180
Chloroform 2 50 0.5 2.0 1.3
Methylene chloride 7 14 6.0 25 12
Inol"!:uics
Aluminum 5 100 10,000,000 17,000,000 15,000,000
Arsenic 5 100 6,400 12,000 9,000
Barium 5 100 170,000 260,000 230,000
Beryllium 5 60 550 1,200 900
Cadmium 5 100 980 1,500 1,300
Chromium (total) 5 100 13,000 17,000 15,000
Cobalt 5 100 7,900 9,000 8,400
Copper 5 100 17,000 21,000 19,000
Lead 5 100 26,000 36,000 34,000
ManJ!:anese 5 100 370,000 640,000 460,000
Mercury 5 20 50 200 80
~ickel 5 100 12,000 16,000 15,000
Vanadium 5 100 25,000 34,000 30,000
Zinc 5 100 44,000 62,000 55,000
a. Arithmetic mean usm2 one-half the detection limit for non-detects.
DEN063.XLS
6-54
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~
V\
Table 6-13
Chemicals Detected in Surface SOU Samples
in the Tire Pile Area
Page 1 of 2
Detection Frequency Total Number of Maximum
Within the Tire Pile Area Samples CoUected in Concentration Minimum Detected Calculated Mean
Chemical (%) Tire PUe Area (pg/kg) (pg/kg) (pg/kg)
Organics
1,1,1,- Trichloroethane 11 9 5 5 NC
2-Methylnaphthalene 11 9 4,600 4,600 NC
Alpha chlordane 56 9 0.25 0.07 NC
Acenaphthene 11 9 770 770 NC
Acetone 11 9 31 31 NC
Aldrin 11 9 0.75 0.75 NC
Anthracene 11 9 260 260 NC
Benzo(a)anthracene 11 9 1,100 1,100 NC
Benzo(a)pyrene 11 9 840 840 NC
Benzo(b)fluoranthene 11 9 740 740 NC
Alpha-BUC 11 9 0.96 0.96 NC
Beta-BUC 11 9 0.58 0.58 NC
Delta-BUC 11 9 2 2 NC
Gamma-BUC 11 9 8.7 8.7 NC
Benzo(k)fluoranthene 11 9 740 740 NC
bis(2-Ethylhexyl)phthalate 22 9 2,400 85 NC
Chrysene II 9 2,000 2,000 NC
4,4'-DDE II 9 2.1 2.1 NC
4,4'-DDT 22 9 0.58 0.32 NC
Dieldrin 22 9 0.24 0.08 NC
Endrin aldehyde 22 9 0.54 0.41 NC
Endosulfan I II 9 2.2 2.2 NC
Endosulfan II 11 9 0.24 0.24 NC
Fluoranthene 11 9 900 900 NC
Fluorene II 9 930 930 NC
Gamma chlordane 22 9 1.9 0.11 NC
DENlOOIS27C.WPS
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~
0\
Table 6-13
Chemicals I>et«ted in Surface SOU Samples
in the Tire Pile Area
Page 2 of 2
I>et«tIoo Frequency Total Number of Maximum
Within the Tire Pile Area Samples Collected in Concentration MInimum I>et«ted Calculated Mean
Chemical (%) Tire Pile Area (pg/kg) (pg/kg) (pg/kg)
Organics (Continued)
Heptachlor 11 9 1.8 1.8 NC
Heptachlor epoxide 11 9 2.4 2.4 NC
Methoxychlor 22 9 1.4 0.5 NC
Naphthalene 11 9 890 890 NC
Phenanthrene 11 9 2,700 2,700 NC
PCB-1260 (Aroclor 1260) 11 9 100 100 NC
Tetrachloroethylene 11 9 18 18 NC
Pyrene 11 9 5,500 5,500 NC
Inorganics
Aluminum 100 8 25,100,000 7,860,000 21,000,000
Arsenic 100 8 5,250 1,400 3,000
Barium 100 8 331,000 124,000 220,000
Beryllium 100 8 1,300 720 1,100
Chromium 100 8 35,200 8,800 19,000
Cobalt 100 8 11 ,500 5,000 9,000
Copper 100 8 46,700 13,400 25,500
Lead 100 8 36,500 7,300 19,000
Manganese 100 8 1,880,000 206,000 830,000
Mercury 25 8 130 46 73
Nickel 100 8 20,500 7,100 14,000
Selenium 14 7 1,000 455 555
Vanadium 100 8 68,300 19,400 44,000
Zinc 100 8 95,500, 44,500, 74,000
.
INC = Not calculated. I
DEN 1.001. S27c.'WP5
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Table 6-14
Subsurface Soil Data Summarv
Detection Minimum Maximum Calculated
Total Frequency Detected Reported Mean
ConstitueDt ObservatiOD (%) (111!1k2) (....11<9) (111!1k2)
Or!!aoics
1,2-Dichloroctbanc 27 7.0 42 130 NC
1,1,1- Trichloroctbanc 61 20 3.9 3.9 NC
I2-ButaDoDc 16 12 44 120 NC
,4'-DDD 58 3.0 0.26 1.2 NC
,4'-DDE 58 20 0.11 0.11 NC
,4'-DDT 26 15 0.34 30 NC
-auoruaoilinc 60 13 53 2500 NC
Mcthvl-2"'1)C11W1ODc 45 4.0 27 170 NC
>cetoDc 45 20 15 160 NC
IldriD 26 8.0 0.15 3.7 NC
CDZCDC 59 20 1.0 1.0 NC
uoraothcnc 34 3.0 52 52 NC
leozoic acid 46 7.0 81 210 NC
)Ct.a-BHC 58 3.0 1.1 6.0 NC
)js(2-eth thalatc 60 47 41 1,800 NC
thalatc 60 8.0 48 170 NC
:bIOI'Oform 61 10 20 4.0 NC
i-n-Butvluhtbalatc 60 5.0 45 110 NC
li-<>ctvlDbthalatc 60 20 43 43 NC
'cldriD 58 20 9.5 9.5 NC
DdriD 26 12 0.11 0.15 NC
DdriD ketone 26 4.0 0.21 0.21 NC
uorantbcoc 34 3.0 69 69 NC
- Chlordane 56 20 0.13 0.13 NC
_-BHC llindaDe) 26 4.0 0.11 0.11 NC
IIMcthvlcoc chloridc 67 41 1.2 120 NC
CB-1260 28 11 270 2,100 NC
bCDaDthrcoc 34 3.0 46 46 NC
bCDol 34 9.0 40 95 NC
~ 34 3.0 75 75 NC
ctracbIoroctbcoc 27 4.0 1.9 1.9 NC
01- 59 5.0 1.0 4.0 NC
Inol'l!anics
l\IumiDum 51 100 6400 25,000,000 NC
IotimODY 11 9.0 30 30,000 NC
\rscoic 51 86 0.86 18,000 NC
arium 51 100 43 1,200,000 NC
c:rvllium 50 76 0.78 21,000 NC
admiUID 51 69 0.82 3,900 NC
bromium (total) 51 96 6.6 83,000 NC
:Iba1t 51 100 5.8 17,000 NC
DIIDCI' 51 100 13 97,000 NC
:yauidc 51 12 0.52 2,400 NC
:ad 51 100 8.3 100,000 NC
47 100 120 1,800,000 NC
[cmJrY 51 43 0.10 1,100 NC
lekcl 51 92 7.7 29,000 NC
i\vcr 39 8.0 23 16,000 NC
auadium 51 96 20 85,000 NC
~ 51 100 43 180,000 NC
RadioDUciides
Lcad-210 (pCI/Jt) 4 75 1.2 1.8 1.5
lutoaiUID-239 3 100 0.10 0.40 0.20
0Wsium-40 20 100 16 27 19
loatiUID-9O 1 100 0.20 0.20 0.20
iIoriUID-228 4 100 0.80 22 1.4
iIoriUID-230 4 100 1.3 21 1.7
232 20 100 0.70 1.7 1.3
raniUID-234 4 100 0.90 29 1.7
raniUID-238 4 100 0.70 1.5 1.2
C '"' DOt calculated.
6-57
DEN064.XLS
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z:
00
Table 6-15
Surface Water Data Summarv
GrouD 1 GrouD 1 Group J
Detection Minimum Maximum Calculated Minimum Maximum Calculated Minimum Maximum Cah:ulated
Total Frequency Detected Reported Mean Detected Reported Mean Detected Reported Mean
Constituent Observation (%) (J1g1kg) (J1g1kg) (J1g1kg) (J1g1kg) (J1g1kg) (J1g1kg) (J1g1kg) (J1g1kg) (J1g1kg)
Ore;anics
I ,2-Dichloroethene 12 75 2.5 730 400 -- --
1,1,1- Trichloroethane 60 62 0.80 31,000 4,400 2.5 0.80 6.3 2.8
1,1,2- Trichloroethane 51 4.0 2.0 3.0 2.5 0.5 --
2-Butanone 46 59 2.1 51,000 12,000 4 4.9 4.5 3.1 52 9.1
Acetone 59 61 4.1 240,000 27,000 3.5 220 58 3.0 16 6.5
di-n-Butylphthalate 55 11 3.9 3.9 4.0 0.80 10 5.3 3.9 3.9 3.9
Methvlene chloride 60 53 0.80 7,700 970 1.3 4.5 2.8 0.60 39 5.1
IOCDD (total) 2 50 0 0.04 0.020 -- --
IPCDD (total) 2 0 0 0.01 0 -- --
iPYrene 55 7.0 10 10 10 - --
Styrene 1 100 -- -- 1.2 1.2 1.2
Inorl!anics
Aluminum 66 80 13 260,000 15,000 62 7,200 1,700 32 6,500 1,200
Arsenic 59 58 4.2 42 19 0.55 6.0 4.0 4.0 5.0 4.9
Barium 65 86 54 1,500 300 50 110 80 50 290 170
lSoron 2 100 120 240 180 -- --
Chromium (total) 65 32 1.2 200 19 2.5 7.5 5.0 1.5 15 4.0
Copper 65 32 1.3 660 34 5.0 25 11 1.0 13 4.7
~anide 62 50 2.5 62 14 5.0 10 7.0 2.5 250 26
luoride 2 50 300 660 480 -- --
vtan2anese 68 99 46 38,000 12,000 9.4 1,200 380 6.9 4,000 600
Mercury 58 33 0.050 1.5 0.46 0.10 2.7 0.60 0.10 3.6 0.6
Nickel 65 55 2.5 250 110 6.0 29 18 3.0 36 13
Selenium 11 64 -- -- 2.0 23 9.1
Vanadium 65 42 0.50 630 50 2.5 21 11 1.0 19 8.5
line 65 80 1.5 1,300 81 1.7 90 36 5.3 230 64
I.. = Not analyzed for or not reported. I
DEN02S .XLS
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Table 6-16
Summary or Chemicals Detected in Sedimeots in SectiOD 6
Page 1 of2
Total Number or Number or DetectioD MiDimum Maximum
Parameter Name Observations Detects NOD Detects Frequency Viglmg) Viglmg)
Orgaoics
1,1 , I-Trichloroethane 15 10 5 67 3.35 110,000.00
1,1,2-Trich1oroethane 12 1 11 8 2.50 18.00
1,I-Dichloroetlwae 15 9 6 60 1.00 3,400.00
1,I-Dechloroethylene 15 6 9 40 2.00 1,800.00
1,2-Dichloroetlwae 4 2 2 50 2.00 6.00
1,2-Dichlorobenzene 15 3 12 20 100.00 900.00
1 ,2-Dichloroethyiene (Total) 7 4 3 57 3.00 570.00
1,2-Dichloropropane 13 3 10 23 2.50 270.00
2,4-Dinitropheool 10 0 10 0 800.00 1,200.00
2,4-Dimethylpheool 5 5 0 100 69.00 310.00
2-ButaooDe 5 5 0 100 33.00 15,000.00
2-Chloropheool 1 I 0 100 50.00 50.00
2-Methyluaphthalene 15 5 10 33 54.00 24,000.00
2-Methylpheool 10 6 4 60 98.00 470.00
3,3 '-Dichlorobenzidine 1 1 0 100 70.00 70.00
4-Methyl-2-peotanone 14 1 13 7 5.00 570.00
4-Methylpheool 4 2 2 50 165.00 390.00
Aceuaphthene 15 1 14 7 165.00 2,400.00
Acetooe 15 4 11 27 4.05 8,400.00
Aniline 1 I 0 100 330.00 330.00
Anthraceoe 15 2 13 13 59.00 1,200.00
Benzo(a)aDlhraceoe 15 2 13 13 87.00 2,400.00
BeDZO(b)f1uorantheoe 15 1 14 7 165.00 3,400.00
BeDZeDe 15 4 11 27 3.35 6,100.00
Gamma-BHC ~) 15 1 14 7 4.00 300.00
Benzo(k)f1uonnthene 15 1 14 7 165.00 3,400.00
bis(2-Erhylhexy1)phthalate 15 9 6 60 120.00 95,000.00
Chlorobenzene 14 1 13 7 2.50 710.00
Carbon disulfide 12 1 11 8 2.50 9.10
Chloroform 8 0 8 0 1.50 3.50
Chryseoe 15 2 13 13 86.00 3,200.00
DibellZONran 15 1 14 7 165.00 1,400.00
Di-n-butylphthalare 15 2 13 13 145.00 2,700.00
2,4-Dichloropheool 15 9 6 60 170.00 2,700.00
4,4'-DDT 14 1 13 7 8.00 280.00
Dieldrin 14 1 13 7 8.00 280.00
Di-o-octylphthalate 15 0 15 0 165.00 3,750.00
ErhylbeDZeDe 15 8 7 53 1.00 95,000.00
Fluonmthene 15 4 11 27 69.00 7,700.00
Methyleoe chloride 14 1 13 7 4.95 710.00
Naphthaleoe 15 7 8 47 81.00 14,000.00
N-Nitrosodiphenylamioe 1 I 0 100 75.00 75.00
Phenaodueoe 15 5 10 33 62.00 6,200.00
DEN10014EB9.WP5
6-59
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I Table 6-16 _2~21
Summary of Chemicals Detected in Sediments in Section 6
.
Total Number of Number of Detection MiDimum Maximum
Parameter Name Observations Detects NOD Detects Frequeacy (pg/mg) (pg/mg)
PCB-I260 (Aroclor 1260) 13 3 10 23 105.00 2,400.00
Tetrachloroethylene 15 9 6 60 3.00 48,000.00
Phenol 1 I 0 100 130.00 130.00
Pyrene 15 6 9 40 50.00 5,500.00
trans-l,2-Dichloroethylene 8 6 2 75 3.35 3,100.00
Trichloroethylene 15 9 6 60 3.35 41,000.00
Toluene 15 11 4 73 3.35 280,000.00
Total Xylenes 15 11 4 73 3.35 580,000.00
V'myl chloride 12 4 8 33 2.00 57.00
IDorgaaics
Silver 12 I 11 8 800.00 3,300.00
Alumimam 13 12 1 92 6,070,000.00 22,300,000.00
Arsenic 10 7 3 70 3,550.00 21,000.00
Barium 14 12 2 86 147,000.00 859,000.00
Beryllium 9 1 8 11 355.00 1,800.00
Cadmium 9 3 6 33 650.00 2,600.00
Cyanide 14 2 12 14 145.00 1,910.00
Cobah 11 9 2 82 5,600.00 18,000.00
Chromium (Total) 14 12 2 86 3,700.00 420,000.00
Copper 14 12 2 86 11,000 159,000.00
Fluorene 15 1 14 7 165.00 1,800.00
Mercury 14 5 9 36 50.00 1,900.00
Manganese 9 7 2 78 476,000.00 1,860,000.00
Nickel 14 11 3 79 9,100.00 22,000.00
Lead 12 10 2 83 5,500.00 2,950,000.00
Antimony 1 1 0 100 29,000.00 29,000.00
Tm I 1 0 100 13,000.00 13,000.00
Vanadium 14 12 2 86 24,500.00 71,000.00
Zinc 14 12 2 86 36,000.00 535,000.00
DEN10014EB9.WP5
6-60
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Section 7.0
Summary of Site Risks
-------
Section 7.0
Summary of Site Risks
Baseline risk assessments (baseline RAs) were conducted for each environmental medium
at the Lowry Site to evaluate the potential for adverse health and environmental effects
caused by actual or potential releases of and exposure to site-related chemicals under
current and hypothetical future conditions. A baseline risk assessment evaluates what
types of risks could be present now and in the future if a site is not remediated or cleaned
up. Under the baseline RA scenarios, EPA would not restrict the use of the Lowry Site
and its resources and would take no action to prevent exposure of people or the
environment to contaminants (the No-Action Alternative). This no-action scenario is used
to assess the need for remedial action, to provide a basis for determining cleanup levels,
and for comparing potential health effects of various remedial alternatives.
The baseline risk assessment for the Lowry Site consists of three volumes and will here-
after be referred to as the Baseline RA. A separate assessment was conducted for each
group of OUs and for lead and radionuclides, as follows:
.
Volume 1: OUs 1&6, which include shallow ground water and subsurface
liquids and deep ground water.
.
Volumes 2A and 2B: OUs 2&3, which include landfill solids and landfill
gas and OUs 4&5, which include soils, surface water and sediments.
.
Volume 2C: sitewide issues relating to lead and radionuclides, and the
relative risk contribution by media.
The Baseline RA for the Lowry Site assumed the following conditions:
DENlOOI53C6.WPS
.
No further remedial actions would be implemented to address hazardous
substances at the site.
.
Interim remedial measures would be discontinued. Existing structures,
such as fences and the ground-water barrier wall, would not be maintained
and would eventually deteriorate. The Surface Water Removal Action
(SWRA) would also not be maintained and would eventually deteriorate.
.
Existing physical structures would not be maintained and would eventually
deteriorate.
.
Hypothetical future use of the Lowry Site would not be restricted and any
type of land use could occur, including agricultural, industrial,
recreational, or residential.
7-1
-------
The results of the Baseline RA will be presented according to each medium and design-
ated au. The site risks presented by lead and radionuclides are presented separately.
Key terms are defined in the ROD glossary.
7.1 Human Health Risks
A baseline risk assessment provides the basis for taking action and indicates the exposure
pathways that need to be addressed by the remedial action. It serves as the baseline,
indicating what risks could exist if no action were taken. This section of the ROD
reports the results of the Baseline RA conducted for the Lowry Site.
Results are presented for each of the four basic components of the risk assessment:
identification of chemicals of concern; exposure assessment; toxicity assessment; and risk
characterization.
7.1.1 Chemicals of Concern
The chemicals of concern (COCs) for each OU were selected from all available Lowry
Site data. Three primary criteria were used to select COCs:
.
Comparing the chemical concentration to background levels to determine if
the concentration in each sample was greater than the concentration
expected under natural background conditions.
.
Determining if the detection frequency of a chemical in a medium was
greater than 10 percent.
.
Toxicity-concentration screening to identify those chemicals, by media, that
may contribute up to 99 percent of the risk.
Figure 7-1 presents the screening steps and selection criteria.
Table 7-1 presents the COCs selected for each medium and the minimum and maximum
detected values for each. Forty-six chemicals were retained as COCs for the OUs 1&6
baseline risk assessment. Thirteen chemicals were selected as COCs for OU 3 and all
49 chemicals detected in subsurface soils were retained as COCs for OU 2. Thirty-six
chemicals in surface water, 33 chemicals in sediments, and 23 chemicals in surface soil
were retained as COCs for OU s 4&5. Radionuclides were detectecI in all media except
landfill gas (no analyses were conducted for radionuclides in landfill gas) but they are not
included in the COC counts above. Separate risk assessments for lead and radionuclides
w~re conducted and are summarized in subsequent subsections (7.1.3, Summary of Lead
Risks; 7.1.4, Summary of Radiological Risks).
DENlOOlS3C6.WP5
7-2
-------
7.1.2 Summary of Exposure Assessment
The exposure assessment identifies:
.
Receptors (people) who could potentially be exposed to media containing
COCs by looking at land use, both onsite and offsite (media may have
migrated from the site) under current and hypothetical future conditions
e.
Pathways of exposure (such as ingestion, inhalation, dermal contact)
e
Geographic locations where exposure could occur (exposure point)
e
How much exposure could occur (exposure point concentrations, fre-
quency, and duration of exposure, the amount of media contacted)
7.1.2.1 Cu"ent Exposure
Currently, the Lowry Site is zoned as agricultural and is only used for asbestos disposal.
Figure 2-2 depicts major current land uses in the vicinity of the Lowry Site.
Currently, employees of WMC are onsite during the work week. There are no on site
residences and offsite receptors include farm residents near the Lowry Site, agricultural
workers, and persons that may use the surrounding farmlands for recreation.
Under current conditions, no onsite or offsite exposures occur. WMC workers are sub-
ject to Federal and State regulations prescribing worker protection requirements to control
exposure and, therefore, potential exposure pathways are not complete. Current offsite
exposures do not occur because COCs have not been detected in media beyond the
Section 6 boundaries to the south, east, and west, nor beyond Section 31 to the north.
7.1.2.2 Hypothetical Future Exposure
Development pressure for the area around the Lowry Site is influenced by projected
population growth within Arapahoe County, economic growth of the City of Aurora, and
the construction of the E-470 Beltway and interchanges. The U.S. Census Bureau proj-
ects a 50 percent increase in the population of Arapahoe County within the next 20 years.
The City of Aurora anticipates mixed use for the area surrounding the Lowry Site, ,
including industrial, commercial and residential. Following completion of the E-470
Beltway construction, it is expected that traffic will increase in the area. It may be
assumed that increases in traffic may lead to increases in new businesses and eventually
new residential development.
Given the potential for population growth and future land uses, three types of potentially
exposed populations were identified: residential; commercial/industrial; and recreational.
DENlOO153C6.WPS
7-3
-------
Hypotheticalfuture exposure settings were developed by integrating popula~ons ?ote~-
tially exposed.with the pathways through which exposure could occur. Settings Identified
include:
.
HypotheticaljUture onsite and offsite residential (adults and children):
Ingestion of ground water
Incidental ingestion of surface soil, subsurface soils brought to the
surface from excavation, sediment, and surface water
Inhalation of volatiles from surface water and sediment
Inhalation of suspended soil and/or dry sediments as particulates
Inhalation of landfill gas emissions
Dermal contact with surface soil, subsurface soil, surface water,
sediment, and landfill gas
Encountering concentrated levels of methane
.
HypotheticaljUture onsite commercial/industrial (worker):
Ingestion of ground water
Incidental ingestion of surface soil and subsurface soil
Inhalation of suspended surface soil as particulates
Inhalation of landfill gas emissions
Dermal contact with surface soil, subsurface soil, and landfill gas
Encountering concentrated levels of methane
.
HypotheticaljUture on site and offsite recreational:
Incidental ingestion of surface soil, surface water, and sediment
Inhalation of suspended soil and/or dry sediment as particulates
Inhalation of landfill gas emissions
Inhalation of volatiles from surface water and sediment
Dermal contact with surface soil, surface water, sediment, and
landfill gas
The baseline risk assessments for the Lowry Site quantified exposure by estimating the
highest exposure that could reasonably occur, the reasonable maximum exposure (RME),
and for some media, the typical exposure-approximating conditions that are most likely to
occur to provide a range of potential exposures. The RME is designed to be a
conservative estimate of exposure that is within the range of possible exposures, but is
higher than typical exposures. Exposure point concentrations and exposure parameter
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values are selected so the total exposure represents the upper 90th percentile estimate of
possible exposures.
Exposure point concentrations were estimated from monitoring data, either directly or
indirectly using simple models. In either case, monitoring data for each medium were
summarized. Statistics used for the summary of each environmental medium vary
because of the nature of the sample collection method (random or non-random), the dis-
tribution of the data in each medium, the variation in detection limits between various
sampling events, and the number of values reported at the detection limit. For ground
water, to control the bias introduced by multiple detection levels spanning several orders
of magnitude, the median of the positively detected values (nondetects were ignored)
from each well was used to generate a geometric mean and a 95th percentile upper confi-
dence limit (95th DCL) on the geometric mean of the median for a specific grouping of
wells (for example, waste-pit well points and shallow ground-water wells within the
source area). If a well had no positive detects for a particular contaminant, one-half of
the lowest detection limit was used to represent the median value.
For all other media, the data were log-transformed, and an arithmetic mean and a
95th DCL of the mean were calculated. A value of one-half the sample quantitation limit
was used in the calculations for all nondetects.
Direct use of monitoring data utilized either the 95th DCL on the appropriate statistical
parameter (mean or median) or the maximum concentration detected if the 95th DCL was
greater than the maximum concentration detected in estimating the exposure point concen-
tration for the RME. When typical exposure conditions were evaluated, average concen-
trations were used as the exposure point concentrations. Models used to estimate the
exposure point concentration at a location where monitoring data were not available used
the 95th DCL or maximum value as an input parameter for RME conditions and the
average concentrations for typical conditions. A basic assumption of the risk assessments
is that no physical, chemical, or biological processes reduce the chemical concentration
over time, and therefore, exposure point concentrations are constant for the duration of
exposure.
Exposure point concentrations for chemicals in ground water were developed for one
onsite and seven offsite locations for different aquifers using various pumping rates
(domestic at 15 gpm and municipal at greater than 200 gpm). Of these eight locations,
the highest concentrations were obtained with the direct use of monitoring data from
shallow ground-water wells in the weathered Dawson aquifer and waste-pit liquid well
points within the source area (the landfill mass). These concentrations, presented in
Table 7-2, were used to evaluate RME conditions for thefuture onsite residential setting.
The maximum detected concentration of chemicals in subsurface soil (see Table 7-1) were
used as the exposure point concentrations for the future onsite residential setting and the
future onsite worker setting. The assumption was made that subsurface soils could be
excavated to 10 feet, spread over the surface, and regraded.
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Human exposure to landfill gas in afuture onsite residence was evaluated at two distinct
locations onsite that corresponded to the origin of the gas: the landfill mass area with
exposure to refuse gas; and the tire pile area with exposure to soil gas.
The assumption was made that subsurface gas would be transported into a home through
a combination of convective and diffusive transport mechanisms. Exposure point concen-
trations inside an onsite residence were obtained by direct use of subsurface gas concen-
trations assuming equilibrium between the home and the subsurface gas and through
modeling which varied the parameters governing gas migration. The highest concentra-
tions were obtained with direct use of subsurface refuse gas data. These exposure point
concentrations are reported in Table 7-3 and were used to evaluate RME conditions for
the future on site residential setting.
Inhalation of landfill gas was evaluated for the future offsite residential setting by estimat-
ing exposure point concentrations along the southwest perimeter of the Lowry Site. This
location was selected because gas migration has occurred about 200 feet beyond the
landfill mass in this area. Four different modeling scenarios were evaluated; the highest
concentrations resulted from assuming a residence had a cracked structural slab. These
were used as the exposure point concentrations for RME conditions in the future offsite
residential settings and are reported in Table 7-3.
Exposure point concentrations for chemicals in surface soil were developed for four
distinct areas on site according to the chemical distribution. The chemical distributions
corresponded with past on site disposal activities. The four areas consist of:
.
The sewage sludge application/leachate injection area (Group 1)
The sewage sludge application area (Group 2)
The leachate spraying area (Group 3)
The tire pile area (Group 4)
.
.
.
It was assumed that future use at the Lowry Site could occur in each of the four areas.
Exposure point concentrations used for RME conditions for the future onsite residential
setting are reported in Table 7-4 for each area. The exposure point concentrations for
Group 4 include only inorganic constituents. Data on organic constituents were evaluated
separately for the Baseline RA. Exposure point concentrations for dust arising from these
four distinct locations were derived with the use of an analytical mass-load model. Dust
concentrations are also reported in Table 7-4.
Surface water data were grouped according to geographic location and creek flow for the
derivation of exposure point concentrations. Three groups were formed:
.
Group 1 included data taken within the unnamed creek, from the toe of the
landfill to the area previously occupied by Pond 3.
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.
Group 2 included samples taken in Section 31, from the area previously
occupied by Pond 3 to the confluence of unnamed creek and Murphy
Creek.
.
Group 3 included samples taken in Section 31 and 30, from the confluence
of unnamed creek and Murphy Creek to the southern portion of Section 30.
It was assumed future onsite residents would use the unnamed creek for recreational
purposes, from the toe of the landfill to the area previously occupied by Pond 3
(Group 1). For this group, exposure point concentrations used for RME conditions and
the future onsite residential setting are reported in Table 7-5. Similar procedures were
employed for the sediment data groupings and are reported in Table 7-5.
Exposure parameters used for the future on site residential RME were obtained from risk
assessment guidance and were not adjusted to account for site-specific conditions.
Typical exposure parameters approximated the 50th percentile of the parameter distribu-
tion and were then adjusted to account for local and regional conditions, such as:
.
Number of days children would be expected to play out-of-doors consider-
ing school schedules and weather conditions
.
Number of days when soil is expected to be frozen, which would limit
ingestion and dust generation
.
Number of days when precipitation exceeds 0.01 inch and dust generation
would be suppressed
Table 7-6 presents RME parameter values for pathways quantified for the future residen-
tial, commercial/industrial, and recreational settings. Absorption of chemicals through
dermal contact was not specifically quantified in any exposure setting because of the
uncertainties associated with this pathway.
Combining exposure parameters for each exposure route for a medium (for example, soil
ingestion) with exposure point concentrations for each chemical in that medium results in
the calculation of a chronic daily intake (CDI) of each chemical for the exposure route
for a medium.
7.1.2.3 Summary of Toxicity Assessment
Chemical contaminants may be divided into two groups according to their effects on
human health. Contaminants may have carcinogenic effects or noncarcinogenic/systemic
effects. Exposure to some of the chemicals detected at the Lowry Site could potentially
result in both types of effects.
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Carcinogenic effects result in or are suspected to result in, the development of cancer.
EP A assumes .a non-threshold mechanism for carcinogens; that is, any amount of expo-
sure to a carcinogenic chemical poses a potential for generating a carcinogenic response
in the exposed organism. EPA has developed a carcino~en-~lassification sy~tem using
weight-of-evidence to classify the likelihood that a chemIcal IS a human carcmogen.
Chemicals are classified by EP A as:
A
Human carcinogen
Bl
Probable human carcinogen; limited human data are available
B2
Probable human carcinogen; sufficient evidence in animals and inadequate
or no evidence in humans
C
Possible human carcinogen
D
Not classifiable as to human carcinogenicity
E
Evidence of noncarcinogenicity for humans
Noncarcinogenic or systemic effects include a variety of toxicological end points and may
include effects on specific organs or systems, such as the kidney, liver, lungs, etc. EPA
believes that thresholds exist for noncarcinogenic effects.
Slope factors (SFs) have been developed by EPA's Carcinogenic Assessment Group for
estimating excess lifetime cancer risks associated with exposure to potentially carcino-
genic cacs. SFs, which are expressed in units of (mg/kg-day)-l, are multiplied by the
estimated intake of a potential carcinogen, in mg/kg-day, to provide an upper-bound
estimate of the excess lifetime cancer risk associated with exposure at the intake level.
The term "upper bound" reflects the conservative estimate of the risks calculated from the
SF. Use of this approach makes underestimation of the actual cancer risk highly
unlikely. Slope factors are derived from the results of human epidemiological studies or
chronic animal bioassays to which animal-to-human extrapolation and uncertainty factors
have been applied (for example, to account for the use of animal data to predict effects
on humans).
Reference doses (RIDs) have been developed by EPA for indicating the potential for
adverse health effects from exposure to cacs exhibiting noncarcinogenic effects. RIDs,
which are expressed in units of mg/kg-day, are estimated threshold levels for daily
exposure above which exposure is considered unsafe for humans, including sensitive
individuals. Estimated intakes of cacs from environmental media (for example, the
amount of a cac ingested from contaminated drinking water) can be compared to the
RID. RIDs are derived from human epidemiological studies or animal studies to which
uncertainty factors have been applied (for example, to account for the use of animal data
to predict effects on humans).
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Toxicity values for COCs are presented in Table 7-7 for carcinogenic effects and in
Table 7-8 for noncarcinogenic effects.
As suggested by the EPA Risk Assessment Forum, the Toxicity Equivalence Factor
(TEF) approach was used for estimating risk from the dioxin-furan congeners without
SFs. Currently, a SF is available for only 2,3,7 ,8-tetrachlorodibenzo-p-dioxin
(2,3,7,8-TCDD). Where a specific congener was not given in the analytical data (that is,
total hexachlorodibenzo-p-dioxins rather than a specific one such as 2,3,7,8-hexachloro-
dibenzo-p-dioxin), the corresponding 2,3,7 ,8-congener TEF was used.
The chromium toxicity values presented in Tables 7-7 and 7-8 are for hexavalent chro-
mium. In the absence of species-specific data, all chromium detected was assumed to be
hexavalent chromium.
Slope factors and RIDs are specific to the route of exposure, for example, oral SFs are
used to evaluate risk through ingestion of a carcinogenic COCo Oral SFs and RIDs are
not available for all COCs identified at the Lowry Site. Table 7-9 identifies the chemi-
cals, by medium, for which toxicity values were not available.
Lead, listed on Table 7-9, does not have an EPA-developed toxicity value for the inges-
tion or inhalation pathways. The toxic effects of lead exposure are correlated with blood
lead levels rather than a daily intake. EPA has developed a model, the Uptake/Biokinetic
Model (U/BK, version 0.5), to assess the potential effects of lead exposure in the most
sensitive population, children ages I to 6 years. The use of the model and results are
discussed separately in Section 7.1.3, Summary of Lead Risks.
Radionuclides, also listed on Table 7-9, were evaluated separately from other chemical
contaminants and are discussed in Section 7.1.4, Summary of Radiological Risks.
7.1.2.4 Summary of Risk Characterization
For carcinogens, risks are estimated as the incremental probability of an individual devel-
oping cancer over a life-time as a result of exposure to the carcinogen. Excess lifetime
cancer risk is calculated from the following equation:
Risk = CD! x SF
where:
Risk = A unitless probability of an individual developing cancer (for example,
one chance in 10,000 or 1 X 10-4)
CD! = Chronic daily intake averaged over 70 years (mg/kg-day)
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SF
= Slope factor (mg/kg-day)"l
Risks are probabilities that are generally expressed in exponential form (1 x 104). An
excess lifetime cancer risk of I x 10-6 indicates that as a reasonable maximum estimate,
an individual has a one-in-I million additional chance of developing cancer as a result of
site-related exposure to a carcinogen over a 70-year lifetime under specific exposure
conditions at the Lowry Site.
EPA uses the general I x 104 to I X 10-6 risk range as a "target range" within which
the EP A strives to manage risks as part of a Superfund cleanup. Although waste
management strategies achieving reductions in site risks anywhere within the risk range
may be deemed acceptable by the EP A risk manager, EP A has expressed a preference for
cleanups achieving the more protective end of the range (for example, I x lQ-6).
Furthermore, although EPA generally uses I x 104 in making risk management
decisions, the upper boundary of the risk range is not a discrete line at I x 104. A
specific risk estimate less than I X 104 may be considered unacceptable based on site-
specific conditions, including any remaining uncertainties about the nature and extent of
contamination and associated risks.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level
over a specified time period (for example, a lifetime) with a reference dose (RID) derived
for a similar exposure period. The ratio of exposure to toxicity is called a hazard
quotient (HQ).
The HQ is calculated as follows:
CDI
Noncancer HQ = -
RID
where:
CDI = Chronic daily intake averaged over the exposure period (mg/kg-day)
RID = Reference dose (mg/kg-day)
The CDI and RID are expressed in the same units and represent the same exposure
period (that is, chronic, subchronic or short-term).
If the CDI (exposure) is greater than the Rfd, the HQ will be greater than one. An HQ
greater than one indicates the potential for an adverse noncarcinogenic health effect from
exposure to the chemical.
A Hazard Index (HI) is generated by adding the HQs for all COCs that affect the same
target organ o~ system. (for e~ample, the liver or respiratory system) within a medium or
across all medIa to which a gIven population may reasonably be exposed. If the HI for
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each toxic end point exceeds one, the potential for an adverse noncarcinogenic health
effect from exposure to the medium is indicated.
To evaluate the potential for adverse effects from exposure to subsurface soil and landftll
gas, the baseline risk assessment used risk-specific values as a screening tool. A risk-
specific value is a concentration that will result in a 1 X ID-6 excess lifetime cancer risk
for carcinogenic effects. A reference concentration is a concentration that will result in a
hazard quotient of one for noncarcinogenic effects. Both risk-specific values and refer-
ence concentrations are calculated with the same media-specific intake parameters devel-
oped for the Lowry Site. Risk-specific values and reference concentrations were then
compared to the exposure point concentrations calculated for subsurface soil and landfill
gas.
The following discussion of OU groups presents the risks associated primarily with the
on site exposure scenario. In general, the onsite exposure scenario results in the greatest
or most significant estimates of risks.
7.1.2.4.1 OUs 1&6: Shallow Ground Water, Subsurface Liquids, and Deep Ground
Water. The highest excess lifetime cancer risk from ingesting water from a well within
the source area, for afuture on site resident adult using RME conditions, is 1 X 10-2.
Three COCs (arsenic at 23 percent; benzo(a)anthracene at 24 percent; and vinyl chloride
at 22 percent) are responsible for about 70 percent of the total risk estimate. With
6 years of exposure, the HI for noncarcinogenic effects through ingestion could be as
high as 47 for an adult and 46 for a child. Five COCs exceed their reference dose and
contribute to the total HI. Table 7-10 presents the excess lifetime cancer risk and non-
cancer HQ for the COCs with the greatest contribution to risk in subsurface liquids.
7.1.2.4.2 OU 2: Landfill Solids. (Landfdl solids are evaluated as subsurface soil 1
to 10 feet below ground surface). The potential for adverse effects of landfill solids
was evaluated on a screening level basis only. Concentrations of four chemicals exceed
their carcinogenic risk-specific values for the ingestion or inhalation pathway in ajuture
onsite residential setting. Concentrations of arsenic, beryllium and PCB-1260, in
subsurface soil, exceed their risk-specific values for the ingestion pathway.
Concentrations of arsenic, beryllium, and chromium (hexavalent), in subsurface soil,
exceed their risk-specific values for the inhalation pathway. The chemical concentrations
that exceed risk-specific values were detected through the Lowry Site and at many were
co-located. The term co-Iocated is explained as follows. Forty-four separate samples
had concentrations of arsenic that exceeded its risk-specific value for ingestion of soil and
inhalation of dust. Thirty-six separate samples had concentrations of beryllium that
exceeded its risk-specific value for ingestion of soil and inhalation of dust.
Concentrations of arsenic and beryllium were co-located in 30 samples. Only one sample
location contained concentrations of all four chemicals that exceeded their risk-specific
values. At selected sample locations, exposure to these chemicals in subsurface soil
would result in an excess lifetime cancer risk greater than 1 x 10"5 for each individual
chemical.
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None of the COCs evaluated in this manner exceed their noncarcinogenic reference
concentration. for ingestion or inhalation. Table 7-11 presents the comparison of
subsurface soil concentrations to risk-specific values calculated at a 1 x 10-6 risk and to
reference concentrations.
Concentrations of two chemicals exceed their carcinogenic risk-specific values for the
ingestion or inhalation pathway in afuture onsite occupational setting. The concentration
of PCBs in one sample exceeds its risk-specific value for the ingestion pathway. The
concentration of chromium in 37 samples exceed its risk-specific value for the inhalation
pathway. Concentrations of PCBs and chromium are co-located at one sample location.
None of the COCs evaluated in this manner exceed their noncarcinogenic reference
concentration for ingestion or inhalation in an occupational setting.
7.1.2.4.3 OU 3: Landf"ill Gas. The potential for adverse effects of landfill gas was
evaluated on a screening level basis only. For the RMEfuture on site residential setting,
exposure point concentrations of all carcinogenic VOCs from within the landfill mass
exceed their carcinogenic risk-specific values for the inhalation pathway. Furthermore,
exposure to these chemicals through inhalation could result in an excess lifetime cancer
risk of one in one, due to the measured concentrations of vinyl chloride within the
landfill mass. A cancer risk of one in one is exceedingly high. Concentrations of five
VOCs with noncarcinogenic effects from within the landfill mass exceed their
noncarcinogenic reference concentrations for inhalation (the HQ for each chemical is
greater than one). Table 7-12 presents the comparison of exposure point concentrations
of refuse gas within the landfill mass to risk-specific values and reference concentrations.
Methane is present within the landfill mass at concentrations above the lower explosive
limit. Methane has been detected above the lower explosive limit outside of the landfill
mass, but not offsite. It therefore presents an explosion hazard under a prescribed set of
conditions (Le., concentrations between 5 and 15 percent by volume and the presence of
a spark source).
Modeled concentrations of 1, I-dichloroethene and vinyl chloride, within a future offsite
residence with a cracked structural slab, exceed their carcinogenic risk-specific values for
the inhalation pathway. Exposure to these chemicals through inhalation would result in
an excess lifetime cancer risk greater than 1 X 1 Q-6 for each individual chemical.
Modeled concentrations of noncarcinogenic VOCs do not exceed their noncarcinogenic
reference concentrations for inhalation. Table 7-13 presents the comparison of exposure
point concentrations modeled from 95th UCL concentrations to risk-specific values and
reference concentrations.
7.1.2.4.4 OU 4: Soil. The highest excess lifetime cancer risk, 4 X 10-5 (summation of
cancer risks from arsenic, beryllium, 2,3,7,8-TCDD, and PCB-1260), was estimated for
afuture onsite resident child ingesting surface soil from the sewage sludge application!
leachate injection area (Group 1, see Figure 6-6). Arsenic contributes 53 percent and
beryllium contributes 28 percent to the cancer risk estimate for Group 1, regardless of the
DENlOOIS3C6.WPS
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age of the receptor soils. Using the same receptor and exposure settings, all remaining
soil groups (2 through 4) had estimated risks equal to or less than those calculated for
Group 1 (Group 2 risk was estimated as 4 x 10-5; Group 3 as 3 x 10-5; and Group 4 as
1 x 10-5; the inclusion of organic data in risk estimates for Group 4 would increase the
risk to 4 x 10-5). The pathway total HI for a future on site resident child ingesting and
inhaling soil from Group 2 is slightly higher at 1.2.
The estimated risks for an adult receptor are similar; ingestion of surface soil from
Group 1 soil results in an estimated risk of 2 x 10-5; 2 X 10-5 for Group 2 soil; 1 x 10-5
for Group 3 soil; and 6 x 10-6 for Group 4 soil. The total pathway risk from ingestion
of soil over a period of 30 years as an on site resident (child and adult) is 6 x 10-5 for
Group 1 soil; 6 x 10-5 for Group 2 soil; 4 x 10-5 for Group 3 soil; and 2 x 10-5 for
Group 4 soil (without the inclusion of organic data).
The estimated excess lifetime cancer risk from inhalation of dust arising from the soil in
Group 1 was 8 x 10-5 for an adult. Estimated cancer risks for a child for all remaining
soil groups were less than those calculated for Group 1. The future on site resident adult
had the highest estimated risks through inhalation of dust arising from the remaining soil
groups (2 through 4), although less than those calculated from Group 1 soil (Group 2 risk
was estimated as 8 x 10-6; Group 3 as 3 x 10-6; and Group 4 as 4 x 10-6). The total
pathway risk from inhalation of dust arising from Group 1 soil is 2 x 10-5 (adult of
1 x 10-5 plus the child of 8 x IQ-6, for a total of 1.8 or 2 x 10-5). Chromium (assumed
to be in the carcinogenic hexavalent form), is the primary contributor to the risk estimate
for inhalation of dust. Table 7-10 presents the excess lifetime cancer risk for the COCs,
within soil from the sewage sludge application/leachate injection area (Group 1), that
contribute to the greatest risk estimates for the future onsite residential setting.
For the scenario in which a future onsite resident child ingests surface soil from the
Group 1 soil, the pathway total HI for noncarcinogenic effects equals 1. The pathway
total III for a future on site resident child ingesting and inhaling soil from Group 2 soil is
slightly higher at 1.2. Other HIs for the ingestion and/or inhalation pathways using
different soil groups or children or adult receptors are below one. Table 7-10 presents
the noncancer HQs for adults and children using for COCs in Group 1 surface soil that
have the greatest contribution to risk in the future on site adult residential setting.
7.1.2.4.5 OU 5: Surface Water and Sediments. Using the on site portion of unnamed
creek for recreational purposes, a child in the future on site residential setting could expe-
rience an excess lifetime cancer risk of 8 x 1
-------
The HI for noncarcinogenic effects was 2 for the fuJure onsite resident child ingesting
acetone and trans-l,2-dichloroethene (each contributes 30 percent of the total HI) in
surface water and 0.4 for ingesting antimony and arsenic (75 percent contribution) in
sediments from recreational use on the onsite section of the unnamed creek. Table 7-10
also presents the noncancer HQ for each cac quantified in surface water and sediments
for exposure to a child in the future onsite residential setting. Table 7-10 also
summarizes the potential maximum cumulative excess lifetime cancer risk for the future
onsite resident.
Exposure to offsite surface water (Group 2 and 3) in a recreational setting resulted in
estimated risks less than 10-6. Exposure to offsite sediments assumed that sediments had
spread beyond the creek banks during periods of high flow. Therefore, sediment data
were used in a residential setting. Childhood exposure to off site sediments (Group 2) in
a residential setting resulted in an estimated risk of 7 x 10"5 from ingestion of arsenic
and dioxins and 4 x 10-6 from inhalation of chromium (IV) and arsenic. Ingestion of
arsenic, manganese, and vanadium by a child in a residential setting resulted in a pathway
HI for noncancer effects of 1. However, these chemicals affect different target organs.
An In should be calculated for each target organ which would result in an HI less than 1
for each target organ.
Childhood exposure to offsite sediments (Group 3) in a residential setting resulted in an
estimated risk of 2 x 10-5 from ingestion of arsenic and beryllium and 6 x 10-6 from
inhalation of chromium (IV) and arsenic. Ingestion of antimony, arsenic, and chromium
by a child in a residential setting results in an In for noncancer effects of 2. Antimony
had an HQ of 1, while the remaining chemicals each had HQ significantly below 1.
Antimony was detected once in one analysis. The uncertainty of the resulting In from
the contribution of antimony is high.
For Sections 30/31 sediments (offsite), a child could experience an excess cancer risk of
2 x 10-5 from ingestion (at RME) of sediments primarily from arsenic and beryllium.
For noncancer effects, the In of 2 is based on the ingestion of antimony and arsenic.
Table 7-14 summarizes the total risk for the future on site residential setting for all
pathways quantified. Cancer risks from all pathways quantified are added together to
obtain a cumulative risk for the exposure setting. The cancer risks presented represent
RME conditions, the full 30-year exposure duration (child and adult) and the highest
exposure point concentrations estimated for each onsite media. Noncancer HIs are added
together to obtain a cumulative risk for each receptor (adult or child) within a pathway.
Adult and child HI's are not additive. Landfill solids and landf1l1 gas are not included in
this summary table because risk from exposure to these media were evaluated on a
screening level basis only and were not quantified.
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7.1.2.5 Uncertainty in the Risk Assessment
Several significant sources of uncertainty impacted the baseline risk assessments. These
have been described in detail in the Baseline RA. To summarize, the major sources of
uncertainty and their effect on the risk assessments include:
.
Use of data from investigations spanning 8 years. The resulting data
base contained a wide variation in sample quantitation limits (SQLs) and a
large number of nondetects. This adds uncertainty to the selection of
COCs and could overestimate or underestimate exposure point
concentrations.
.
The prediction of human activities that lead to contact with media and
exposure to chemicals is highly uncertain. Assumptions used to estimate
RME conditions may lead to an overestimation of risk.
.
Simplifying assumptions used to estimate exposure point concentrations
may result in an overestimation of exposure. For example, it was
assumed that: contaminant concentrations remain constant over time; all
dust originates from soil contaminated at the 95th DCL concentration; and
equilibration occurs between subsurface refuse gas concentrations and
concentrations inside a home constructed on the landfill.
.
Toxicity data and the assumptions made in using toxicity values (for
example, all chromium was assumed to be present in the hexavalent form,
and bioavailability was assumed to be 100 percent) could result in an
overestimation of risk. On the other hand, the unavailability of toxicity
values for all COCs could result in an underestimation of risk.
.
Risk and doses within an exposure route are assumed to be additive
when, in fact, synergisms and antagonisms occur. This could act to
overestimate or underestimate risk.
.
The prediction of risks associated with the dermal exposure pathway is
difficult since mechanisms to quantify the contribution of dermal absorption
are not well established and considerable uncertainty surround estimates of
dermal exposure and risk. As a result, the uncertainty associated with the
dermal route of exposure necessitates excluding the dermal contribution
from the other routes of exposure.
7.1.3 Summary of Lead Risks
Exposure to lead cannot be evaluated through the same methodology used in the baseline
risk assessments. Toxicity values cannot be determined because research has not identi-
fied a threshold below which no adverse health effects occur. Therefore reference doses,
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for evaluating the potential for noncancer effects, cannot be developed. Lea~ is also.
thought to be. carcinogenic through prolonged low dose exposure; however, Its noncarcm-
ogenic effects on infants and children are more serious because they are manifested in a
shorter time period than the onset of cancer.
Toxic effects of lead exposure are correlated with blood lead levels, and therefore, blood
lead levels have been determined to be an appropriate benchmark for exposure. The
Uptake/Biokinetic Model (U/BK, version 0.5) developed by EPA, allows the estimation
of blood lead levels in infants and children (zero to 7 years of age) from exposure to lead
in environmental media. This model was used to evaluate the potential for adverse health
effects in infants and children exposed (current and potential future) to lead in environ-
mental media at the Lowry Site by estimating the percent of children that would have a
blood lead level greater than the "level of concern" of 10 p.g/dl established by the EPA
and Centers for Disease Control (CDC).
Lead was detected in ground water, soil, surface water, and sediments at the Lowry Site.
The summary statistics for lead in each medium have been presented in Tables 7-2
through 7-5. Potential receptors and exposure pathways and, therefore, possible exposure
settings, have also been described in Volume 2C of the Baseline RA. The most
conservative setting involving children to 7 years in age is the future on site residential
setting. Because the U/BK model is specific to children, only the following pathways
were considered in this evaluation:
.
Ingestion of ground water
Incidental ingestion of surface soil and subsurface soil from an excavation
Ingestion of indoor dust derived from outdoor soil
Inhalation of suspended soil as particulates
.
.
.
Incidental ingestion of surface water and sediments from the unnamed creek were not
included in this evaluation because it was assumed that a child under the age of 7 would
not leave the house to play in the creek. Dermal exposure was not evaluated because
percutaneous absorption is not considered a significant route of exposure for inorganic
forms of lead.
Exposure point concentrations of each medium were taken from the sitewide Baseline
RA. The future on site residential setting evaluates ground water using data from shallow
ground-water wells in the weathered Dawson aquifer and waste-pit liquid well points
within the source area (Table 7-2); soil from the sewage sludge application/leachate
injection area (Table 7-4); and dust derived from soil in this area (also Table 7-4). The
U/BK model default intake parameters reflect the central tendency of each parameter for
the e~pos~ popula~on of zero to 7-year-olds. Table 7-15 presents the default parameters
used m this evaluatIon. The U/BK model includes ingestion of lead in the diet and in
lead-based paint. Lead-based paint was not included in the evaluation for the Lowry Site
because of the assumption of new residential development. New developments do not
contain lead-based paint. The U/BK model can be effectively employed without
DENlOO153C6.WP5
7-16
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including ingestion of paint. Ingestion of lead in the diet was included using default
intake and exposure point concentrations.
The D/BK model results in a frequency distribution that displays the probability density
corresponding to the estimated mean blood lead level concentration for a given exposure
setting. For the future on site residential setting, 6 percent of the children ages zero to
7 years were estimated to have blood lead levels above 10 JLg/dl. Uptake of lead from
ground water had the greatest contribution to total lead uptake.
7.1.4 Summary of Radiological Risks
A radiological risk assessment was prepared separately from the assessment of chemical
risk from the Lowry Site. Refer to Volume 2C of the Baseline RA for details on the
assessment for radionuclides. While much of the data needed for a radiological risk
assessment is similar to that required for a chemical risk assessment, the procedures used
to characterize the radionuclide contaminants and estimate exposure are different.
7.1.4.1 Contaminated Media and Exposure
As previously stated, radionuclides were detected in all media except landfill gas. With
the exception of gross alpha and gross beta, characterization of radionuclides in gas was
not conducted. Because specific isotopes were not identified, exposure to radionuclides
in landfill gas was not quantitatively evaluated in this ROD.
The following steps were used to select the radionuclides in each media to be carried
through the risk assessment: an evaluation of the detection frequency; a comparison to
background concentrations; a determination of parent radionuc1ides; and an elimination of
radionuclides with short half-lives.
Table 7-16 lists the risk assessment radionuclides detected in each medium.
Potential receptors and exposure pathways, and therefore, possible exposure settings were
described in the sitewide Baseline RA for chemical contaminants. Further, it was
assumed that all future offsite settings would result in lower exposures than future on site
exposures. Consequently, future offsite exposures were not evaluated for radionuclide
exposure.
Dermal contact with radionuclides was not included as an exposure pathway because
percutaneous absorption is not considered a significant route of exposure for radio-
nuclides. Therefore, dermal exposure was not evaluated in this Baseline RA.
However, radionuclides, unlike chemicals, can have deleterious effects on humans with-
out being taken into, or brought in contact with, the body. This is because high energy
beta particles and photons from radionuclides in contaminated air, water, or soil can
travel long distances with only minimum attenuation in these media before depositing
DEN 1 00 1 53C6.WPS
7-17
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their energy in human tissue. Therefore, external radiation exposure was included as an
exposure pat1tway for evaluation in this Baseline RA.
7.1.4.2 Summary of Toxicity Assessment
EPA classifies all radionuclides as human carcinogens (Group A) based on their property
of emitting ionizing radiation and the extensive weight of evidence provided by epidemio-
logical studies of radiogenic cancers in humans. EP A generally evaluates potential
human health risks based on radiotoxicity, considering only the carcinogenic effects of
radionuclides. One exception to this is uranium, which is a kidney toxin as well as a
carcinogen. Given that kidney toxicity may occur prior to the onset of cancer from
exposure to uranium concentrations in drinking water, EPA has developed a reference
dose for chronic oral exposure to uranium.
7.1.4.3 Summary of Risk Characterization
Residential ingestion of ground water at the RME from a future onsite domestic well
within the source area could result in an excess lifetime cancer risk of 5 x 1 Q4 from
radionuclides. Three radionuclides are responsible for the majority of the risk:
radium-226 contributes a risk of 1.9 x 104 (31 percent); lead-210 contributes a risk of
1.5 x 104 (25 percent); and potassium-40 contributes a risk of 1.1 x lQ4 (18 percent).
Radium-226, lead-21O, and potassium-40 are naturally occurring radionuclides and both
radium-226 and potassium-40 were detected in upgradient (background) ground-water
samples (lead-21O data are not available). Concentrations of the two radionuclides in
upgradient wells results in a total risk of 2 x lQ4 with radium-226 contributing a risk of
1.3 x 104 (86 percent) and potassium-40 contributing a risk of 2.2 x 10-5 (14 percent).
Risks from ingestion of radionuclides in upgradient ground water (for example, water
with background or naturally-occurring concentrations) are approximately equivalent to
those onsite. Table 7-17 presents a summary of radiological risks onsite and upgradient
(or offsite).
The HQ resulting from ingestion of uranium at the RME, for a future onsite resident
child, was estimated as 2.3 and as 1.0 for an adult. These HQ values indicate the poten-
tial for an adverse noncarcinogenic health effect. The HQs for children or adults ingest-
ing uranium in upgradient (or offsite) wells was estimated to be below I (0.4 and 0.2,
respectively).
The concentrations of four radionuclides in subsurface soil exceed their carcinogenic risk-
specific values for the ingestion, inhalation, and external exposure pathways in the future
onsite residential setting. The maximum concentrations of potassium-40, lead-21O,
thorium-228, and uranium-238 in subsurface soil exceed their risk-specific values, which
were derived for soil ingestion, particulate inhalation, and external exposure assuming
subsurface soil was excavated and spread on the surface. Exposure to these radionuclides
in subsurface soil would result in an excess lifetime cancer risk greater than 1 x 10-6 for
DENlOOlS3C6.WP5
7-18
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each individual radionuclide. Maximum concentrations of potassium-40 and thorium-228
in background subsurface soil also exceed their resPeCtive carcinogenic risk-specific
values. Table 7-18 presents the comparison of on site and background concentrations to
risk-sPeCific values corresponding to a 10-6 cancer risk.
An excess lifetime cancer risk of 4 x 10-7 was estimated for the future onsite residential
setting from ingesting surface soil from the sewage sludge application/leachate injection
area (Group 1). Inhalation of soil suspended as dust from this area resulted in a 7 x 10"7
excess lifetime cancer risk estimate. External exposure to these soils resulted in an esti-
mated risk of 4 x 1Q4 from radium-226 (97 percent of the total risk estimate). How-
ever, since radium-226 is a naturally occurring element, the background risk was also
estimated. The excess lifetime cancer risk from external exposure to background concen-
trations of radium-226 is 5 x 10-4; and is basically the same risk that was calculated for
on site external exposure. If radium-226 is not considered in estimating the risk from
external exposure to surface soil in the sewage sludge application/leachate injection area,
the risk drops to 1 x 10"5. Table 7-19 presents a summary of on site and background
radiological risk from exposure to surface soil.
Although external exposure from contact with surface water is possible, only incidental
ingestion of surface water was evaluated quantitatively. Two surface water sampling
points were available for radionuclide analysis; one onsite and one offsite. The assump-
tion was made that the concentrations of radionuclides at the two sampling points were
representative of all surface water and, therefore, could be used as exposure point con-
centrations for thefuture on site residential setting. Ingestion of surface water by afuture
onsite resident child (ages 7 to 18 years) using the unnamed creek for recreation could
result in an excess lifetime cancer risk of 2 x 10-7.
For the future on site residential setting, the only exposure to sediments for children or
adults that results in an excess lifetime cancer risk greater than 1 x 1 Q-6, is external
exposure. Radium-226, potassium-40, and thorium-228 contribute to 98 percent of the
estimated risk of 1 x 10"3. As all three radionuc1ides are naturally occurring, the excess
lifetime cancer risk of background concentrations was also calculated. The background
risk from external exposure was estimated as 9 x 10-4, indicating that on site and back-
ground risks are approximately equal. Table 7-20 presents a summary of the onsite and
background radiological risk.
Table 7-21 presents a summary of radiological risk from all exposure pathways. Total
radiological risk estimated for background and on site concentrations is the same,
2 x 10-3. Radionuclides present in media on site do not appear to present an increased
risk over background, using exposure conditions outlined in this assessment.
7.1.4.4 Uncertainties
Uncertainties in the data include the lack of a rigorous evaluation of data useability, due
to the lack of laboratory documentation and the limited quantity of radionuclides data
DENlOOlS3C6.WPS
7-19
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available. The representativeness of the data is questionable and affects the estimation of
external dose and the risk from external exposure. External exposure assumes a uniform
distribution of radionuclides in the environmental medium of interest. Uniformity in
distribution is difficult to determine with limited data.
Shielding was not accounted for in the estimation of external exposure. Shielding can
reduce the exposure by a factor of 0.5, thereby reducing the risk from exposure. The
toxicological data base is limited for low-level environmental exposures; most available
data on risk are from high-dose radiation exposures (such as survivors of the atomic
bomb). Extrapolation to low-dose environmental exposures is subject to much scientific
debate. Consequently, the degree of conservatism introduced into estimates of risk from
incomplete toxicological data cannot be estimated.
7.1.5 Summary of Environmental Risks
The Lowry Site ecological assessment (EA) consisted of:
.
An ecological site description
.
Identification of ecological chemicals of concern (ECOCs)
.
Identification of the actual and potential ecological receptors
.
Characterization of ecological exposure pathways
.
Identification of ECOC exposure levels considered to have no observable
adverse effects from literature references
.
Comparison of potential exposure levels to receptors with exposure levels
considered to have no observable adverse effects
.
A qualitative description of uncertainty
The ecological assessment, included in Volume 2B of the Baseline RA, focused on poten-
tial effects on terrestrial wildlife from ingestion of contaminated media.
7.1.5.1 Ecological Setting
The ecological setting of the Lowry Site has been described in other sections of this
~ocument. A list of threatened and endangered species that could be present in the vicin-
Ity of the Lowry Site is provided as Table 7-22. None of these species have been
observed at the site and it is unlikely that these species would be found onsite. However,
the area surrounding the Lowry Site could provide a habitat for these species, and there-
fore, they were considered potential ecological receptors.
DENlOOI53C6.WP5
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7.1.5.2 Ecological Chemicals of Concern
The EA was based on data collected during the Rls for OUs 2&3 and 4&5. Only data
from surface soil (zero to 1 foot), surface water, and sediment were used in the assess-
ment. Landfill gas was not addressed because of a lack of literature information on the
toxicity of gas to ecological receptors. Landfill solids were not addressed because it was
assumed that the most significant exposures for terrestrial organisms would result from
the upper 1 foot of the soil column. Because of the transient nature of terrestrial recep-
tors, it was assumed that potential receptors would have access to the entire site. There-
fore, data were summarized by media.
Chemicals detected in surface soil, surface water, and sediments were initially screened
on the basis of comparisons with background concentrations, frequency of detection, and
relative toxicity for use in the EA. The first two screening steps follow the procedure
outlined in the Baseline RA. The relative toxicity screening step eliminates inorganic
constituents that are commonly found in the environment, act as macronutrients to living
organisms, and/or are relatively nontoxic to environmental receptors. Table 7-23 lists the
constituents eliminated from each medium because of their relative nontoxicity.
Table 7-24 lists the COCs evaluated in each medium and their maximum detected
concentration.
7.1.5.3 Exposure Assessment
No aquatic organisms were observed within the limited aquatic habitat onsite, therefore,
aquatic organisms were not considered potential receptors to environmental contamina-
tion. Terrestrial wildlife are considered potential receptors as they can use the Lowry
Site as habitat and become exposed to site-related contamination through daily activities.
Other potential receptors include terrestrial and riparian vegetation growing in contami-
nated media.
Exposure pathways for terrestrial wildlife may include:
.
Foraging and ingestion of vegetation or invertebrates contaminated through
biomagnification or bioaccumulation
.
Ingestion of vegetation, which may result in the incidental ingestion of
surface soil and the inhalation of surface soil as dust or volatile constituents
in surface soil
.
Ingestion of surface water and inhalation of volatile constituents volatilizing
from surface water
.
Incidental ingestion of sediments while drinking or searching for food in
the unnamed creek
DENIOOIS3C6.WP5
7-21
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Dermal contact with soil, surface water, and sediment while burrowing or
grooming
Terrestrial wildlife currently use the Lowry Site and could continue to use the site in the
future, regardless of planned land use. Therefore, this EA roc~sed on direct ex~osures
(ingestion of media) to terrestrial wildlife. Because the habitat In the area OCCUpied by
the former landfill is highly disturbed and of relatively poor quality, exposures resulting
from biomagnification and bioaccumulation of contaminants were considered minor and
therefore, not addressed. Other exposure routes affecting terrestrial wildlife including
inhalation and dermal contact and effects to vegetation were also not addressed because of
the lack of quantitative literature values for quantifying exposure.
.
7.1.5.4 Ecological Effects Assessment
The potential for adverse effects to terrestrial wildlife was assessed through comparison
of potential intake through ingestion with an appropriate toxicity value. Toxicity values
were obtained from the literature for all COCs in each media evaluated. The lowest
observable adverse effect level (LOAEL), no observable adverse effect level (NOAEL),
and the lethal dose that kills half of the population exposed (LDso) were obtained from
toxicological investigations using laboratory or wild animal species. Data related to
chronic oral exposure studies (gavage, drinking water, or diet) were used preferentially to
data derived from intraperitoneal or intramuscular studies. Inhalation toxicity data were
not included. Toxicity data are media- and species-specific and were not available for all
COCs.
LOAELs were used in comparison to doses received from ingestion of soil and sediment
for small mammals. Each constituent-specific LOAEL was divided by an uncertainty
factor to adjust the value to account for the uncertainty involved with data comparisons.
Small mammal soil ingestion rates, in mg soil/kg body weight/day, were available in the
literature. Small mammals ingest soil during feeding, grooming, and burrowing activities
whereas no data are available for soil ingestion in larger animals. Species specific (rats,
mice, or rabbits) soil ingestion rates were multiplied by the maximum constituent concen-
tration in surface soil or sediments. The adjusted LOAEL was then compared to the dose
received through ingestion (using the species on which the LOAEL was developed). If
the dose received exceeded the adjusted LOAEL, an adverse effect to ecological health
may exist and further evaluation of ecological exposure would be appropriate.
For surface water, the preferred toxicity value is the NOAEL. If an NOAEL was not
available, a LOAEL was used and then an LDso. Water criteria were calculated using
drinking water ingestion rates for laboratory animals to represent rates for small
mammals in the wild. This will result in conservative criteria because most small
mammals in the wild do not consume water on a regular basis. The NOAEL (or other
toxicity value) was divided by both water intake rate for an appropriate species and an
uncertainty factor to estimate a water concentration (termed water criteria) associated with
the no adverse effects. The water criteria were then compared to the maximum detected
DENlOOlS3C6.WP5
7-22
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concentration of the constituent. If the maximum concentration detected in surface water
exceeded the water criteria, the potential for adverse effects to terrestrial receptors using
surface water within the Lowry Site may be present.
For surface soil, the ingestion of aluminum, barium, cadmium, cobalt, iron, and octo-
chlorodibenzodioxins exceeded their respective adjusted LOAEL value. In addition,
because of the lack of toxicological information for acetone and ammonia, as they pertain
to environmental receptors, these two chemicals could not be evaluated.
For sediments, ingestion of aluminum, barium, cobalt, iron, lead, and heptachloro-
dibenzo-p-dioxin exceeded their respective adjusted LOAEL value. Due to the lack of
toxicological information for acetone, ammonia, aniline, and benzene, these chemicals
could not be evaluated for their effects on environmental receptors.
For surface water, maximum concentrations of aluminum, antimony, barium, cobalt,
iron, mercury, vanadium, benzene, 2-butanone, 1,2-dichloroethene (trans and total),
2,4-dichlorophenol, methylene chloride, 2-methylnaphthalene, 2-methyl phenol, 4-methyl-
phenol, 4-methyl-2-pentanone, octochlorodibenzodioxins, phenol, tetrachloroethene,
trichloroethene, toluene, and vinyl chloride exceeded calculated water criteria.
On the basis of comparisons in this assessment, maximum detected concentrations of
select inorganic and organic chemicals in surface soil, surface water, and sediments may
result in adverse effects to terrestrial wildlife.
7.1.5.5 Uncertainties
The EA has a high level of uncertainty as a result of the many assumptions made and
issues addressed. The following assumptions contribute to the uncertainty:
.
All soil and sediment consumed was from a contaminated source.
All water ingested was from onsite contaminated surface water.
The maximum detected concentration of each constituent in each medium
represents the potential exposure concentration.
.
.
These assumptions act to overestimate intake, since terrestrial species are mobile and
have access to multiple sources of food and drinking water. Not all terrestrial species
would be contaminated at the maximum concentration, and not all would ingest food and
water from the Lowry Site.
The assumption was made that all chemicals in each media were 100 percent bioavail-
able, which overestimates the true dose received. For example, chemicals bound to soil
may not be readily digested and may pass through the gastrointestinal system; or, chemi-
cals ingested may be metabolized and rendered nontoxic.
DENIOOlS3C6.WPS
7-23
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In addition, chemical interactions were not addressed. The true toxicity of an environ-
mental mediqm cannot be known unless synergistic and/or antagonistic effects can be
determined. The total hazard of each media has not been addressed because comparisons
made in the EA were on a constituent-by-constituent basis.
Soil and sediment consumption and water ingestion were estimated using laboratory ani-
mals to represent small mammals. This may overestimate intake and the potential hazard
since correlations between standard lab animals and actual receptor species are not
known. Uncertainty factors were applied to account for this. However, there is no
means to measure the magnitude of uncertainty involved.
The EA only quantified the ingestion route. Other routes, such as inhalation and dermal
contact, may have a significant impact for small mammals that burrow in the ground.
The potential hazard to small mammals may therefore have been underestimated.
7.2 Baseline Risk Assessment Summary
Actual or threatened releases of hazardous substances from the Lowry Site, if not
addressed by implementing the response action selected in this ROD, may present an
imminent and substantial endangerment to public health, welfare, or the environment.
The most significant risks are summarized in Subsection 7.1.2.4.
DENIOOI53C6.WP5
7-24
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Preliminary List of
Chemicals of Potential -. Exceeds Background
Concern Concentrations
~
No
Will not be
Considered
as a COPC
-J t
I No
tV
VI
Is Detection
Frequency> 10"10
Ves
Is Toxici!y
~ Concentrallon
Screen >99%
Ves
No
Is Distribution
Indicative of Localized Ves
)I Contamination?
DEN Graph/Lowry ROD/154
or
Are Detective Limits Ves
Excessively High
or
Is there Historical
Confirmation
or
Does it Exceed
an ARAR?
or
Is it Difficult
to Treat
or
iN'
Is it 'A' Rated
caT:'"
Is it a Developmental
Toxicant?
+ No
Does the Maximum
Concentration Exceed
ARARs?
Ves
~
Evaluate as a
RA CO PC
Do Detect Limits Exceed
Health - Based Criteria
Ves
Yes
J
)I
Discuss Qualitatively as
a CO PC in an Appendix
No
Will not be Considered
as a CO PC
Yes
Evaluate Quantitatively
as a Hot Spot
in an Appendix and
Discuss In Uncertainty
Yes
Yes
Ves
Ves
Are there Media
Specific Concerns?
. Persistance
. Bioaccumulate/Bioavailable
. Solubility
. Volatility
Ives
lN'
Discuss Qualitatively as
a CO PC in an Appendix
Figure 7-1
SELECTION CRITERIA FOR THE CHEMICALS OF
POTENTIAL CONCERN
LOWRY RECORD OF DECISION
-------
I Table 7-1 Page 1 Of3!
MinimumlMaximum CouceotraDons of Coof..min..nts of CODCel'D
OUs 116 OUs 2/3 OUs 4/5
Subsurface Subsurface Landfill Surface Surface
Liquids Soil Gas Soil Water Sediment
Chemical (,IgIL) (JIg/kg) (,IgIm3) (JIg/kg) (pgIL) (pgIkg)
0rgaDics
1,l-Dichloroethane 2/1,100,000 3oomO,OOO 1/150,000
1,l-Dichloroethene 0.8/14,000 170/18,000 6.4/5,000 2/1,800
1,2-Dichloroethane 3/1,800,000 42/30 110/68,000
1,2-Dichloroelhene 1/160,000 2/730
1,4-Dichlorobenzene
1,1,1- Trichloroethane 3.9/3.9 38/270,000 4/31,000 6,110,000
1,I,2-Trichloroethane 3/100
1,2,4- Trichlorobeozene 8.5/1,700
1,1 ,2,2-Tetrachloroethane 66/66
2,4-Dichlorophenol 22/160 26/190 170/2,700
2,4-Dimethylphenol 14/920
2,4-Dinitrophenol 500/500
2,3,7,8-TCDD 5 x 1(1/ O.02Il~ 0.04/0.04" 0.1/5.6"
1.1 x 10-'
2-Butanone (MEK) 17/230,000 44/120 1/38,000 1/1 3.1151,000 33/15,000
2-Ch10r0phenol 8/8
2-Hexanone 49/270 4n,400
2-MelhylDaphthalene 3/44,000 4.7/10 54/24,000
2-Melhylphenol 87/4,100
4,4'-DDD 0.26/1.2
4,4'-DDE 0.1110.11
4,4'-DDT 0.34130
4-Ch1oroaniline 53/2,500
4-Melhylphenol 380/6,600
4-Melhyl-2-pentanone 4/960,000 2.7/170 3.7/27,000
Acetone 4/3,000,000 15/160 3/240,000
Aldrin 0.1513.7
AniliDe 330/330
Benzene 1/970,000 1/1 10/190,000 1.5/180 2/6,100
Benzo(a)anthracene 84/84
Benzo(b)tluoranthene 52/52
Beozoic acid 81/210
Benzyl alcohol 7.2/1,900
beta-BHC 1.1/6
bis(2-chloroethyl)elher 3/3
bis(2-Ethylhexyl)phlhalate 1/22,000 46/2,200 49/95,000
Butylbenzylphlhalale 48/170
Carbazole 7/12
Carbon disulfide 22/160,000 912S
Carbon tetrachloride 15/26,000
DENI0015364.WPS
7-26
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I Table 7-1 Page 2 of31
MiDimumlMaximum Coaceotratious of Contaminants of CODCeJ'l1
OUs 1/6 OUs 2/3 OUs 4/5
Subsurface Subsurface Landfill Surface Surface
Liquids Soil Gas Soil Water Sedimeot
Chemical (pg/L) (,&g/kg) (,&gIm1) (,&g/kg) (,£gIL) (,&g/kg)
Orgaoics (cootiDued)
Chloroethanc 2/260
Chloroform 0.6156,000 214 1914,000 113
di-n-Butylphthalate 45/110
di-n-Octylphthalate 5.7/1,200 43143
Dioenzofuran 2.0 x 10"1
1.4 x 10-'
Dieldrin 9.519.5
Endrin 0.1110.15
Endrin ketone 0.2110.21
Ethylbenzene 1.11340 4/95,000
Ethylene dibromide 0.1210.28
FIuo1'llD1hene 261200 69/69 69n,7oo
gamma Chlordane 0.13/0.13
gamma-SHC 0.1110.11
Methylene chloride 3/440,000 1.21120 421840,000 In,7OO
Napththalene 2.0/110,000
PCB-I260 270/2,100 200n,6OO 17012,400
Pentachlorophenol 4/4,100
Phenanthrene 4.211,700 46/46 6216,200
Phenol 40/95 73/4,100
Pyrene 75n5
Tetrachloroethylene 0.91340,000 1.911.9 0.7/2,300 3/48,000
Toluene 0.9/11,000,000 1/4 19/1,400,000 2111 1128,000 3/280,000
T1'8IIS-l,2-Dichloroethene 5.7/56,000
traDs-l ,3-Dechloropropane 2.213.0
Trichloroethylene 4n,7oo,000 0.6/2,500
Vmyl chloride 2.611,800 77/680,000 27/9,600 2157
Xylenes 171120,000 1.3/9,700 41580,000
IDOrgauics (Metals)
Aluminum 6,40012.5 x 10' 7,900/2.8 x l
-------
Table 7-1
MiDimum/Maximum CoacentnUioDs or C~nt"min"nts or CODCeI'D Page 3 or3
OUS 116 OUs 1/3 OUs 4/5
Subsurface Subsurface Landfill Surface Surface
Liquids Soil Gas Soil Water SedilDeat
CbemicaI (,IgIL) (,IgIkg) (JIgIm2) (JIgIkg) (,!gIL) (JIgIkg)
IDorg8llics (Metals) (coDtiDned)
Cyanide 0.5212,400 0.9/4,900 81250 0.29/2,300
Fluoride 0.66/660
Lead 1/510 8.3/100,000 7.3/150,000 5/290 6.7/2,950,000
Manganese 180nO,OOO 120/1,800,000 200/2,700,000 6.9/38,000 380/1,900,000
Mercury 0.1/1,100 0.13/1,000 0.1/1,900
Nickel 13/2,000 7.7/29,000 7.1/130,000 2.8/42,000
Silver 2.3/16,000 3.1/9,800
Thallium 0.34n60
Vanadium 20/85,000 19/140,000 1.21630 12nt,000
Zinc: 43/180,000 44/340,000 13/540,000
RadioDDclides
RadiolWClides I NA NA I NA NA NA
DEN 1 0015364.WP5
7-28
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DENlOO14EFC.WP5
Table 7-2
Ground-Water Exposure Point
Concentrations for the
Hypothetical Future
Onsite Residential Setting
Page 1 of 2
Onsite-Source Area Wells
9S UCL of Geometric
Mean of the Median
Chemical (pgll)
1,1-Dichloroethane 520
1,1-Dichloroethene 83
1,2-Dichloroethane 590
1,2-Dichloroethene 140
1,4-Dichlorobenzene 21
1,1,2- Trichloroethane 29
1,2,4- Trichlorobenzene 18
1,1,2,2-Tetrachloroethane 31
2,4-Dichlorophenol 31
2,4-Dinitrophenol 220
2,3,7,8-TCDD 0.00053
2-Butanone (MEK) 980
2-chlorophenol 8
2-Hexanone 45
2-MethyInaphthalene 58
4-Methyl-2-pentanone 520
Acetone 2,800
Benzene 270
Benzo(a)anthraceoe 17
Benzyl alcohol 53
bis(2-<:hloroethyl)ether 3m
bis(2-ethylhexyl)phthalate 82
Carbazole 12
Carbon tetrachloride 40
Chloroethane 62
Chloroform 49
di-n-Octylphthalate 22
Dibenz.ofuran 4
Ethylene dibromide 49
Fluoranthene 18
Methylene chloride 270
Naphthalene 56
7-29
-------
DENlOO14EFC.WPS
Table 7-2
Ground-Water Exposure Point
Concentrations for the
Hypothetical Future
Onsite Residential Setting
Page 2 of 2
Onsite.Source Area Wells
9S VCL of Geometric
Mean of the Median
Chemical (pgll)
Organics
Pentachlorophenol 130
Phenanthrene 36
Tetrachloroethylene 190
Toluene 1,600
trans-l,3-Dichloropropene 3m
Trichloroethylene 250
Vinyl chloride 99
Inorganics (Metals)
Arsenic 110
Chromium (IV) 40
Cobalt 45
Lead 61
Manganese 4,300
Nickel 230
Thallium 61
Note: An "m" after the value indicates it is the maximum
concentration detected rather than a 95 UCL of the geometric
mean of the median.
7-30
-------
Table 7-3
Subsurface Soil and Landfill Gas Exposure Point Concentrations
Page 1 of 2
Landf"ill Gas OfTsite
Subsurface Soil RME Landf"all Gas Onsite Modeled RME
Concentration RME Concentration Concentration
Chemical (mglkg) (pg/uf) (pg/m3)
Organics
1, 1-Dichloroethane 129,571 m
1, 1-Dichloroethene 8,669 1.17
1,2-Dichloroethane 130m 1,498 m
1,1 , I-Trichloroethane 3.9m 37,061 3.65
2-Butanone (MEK) 120m 38,282 m
4,4, '-DDD 1.2m
4,4'-DDE 0.11 m
4,4'-DDT 30m
4-Chloroaniline 2,500 m
4-Methyl-2-pentanone 170m
Acetone 160m
Aldrin 3.7 m
Benzene 1m 12,541
Benzo(b )fluoranthene 52m
Benzoic acid 210m
Beta-BHC 6m
bis(2-Ethylhexyl)phthalate 1,800 m
Butylbenzylphthalate 170m
Carbon disulfide 22,066
Chloroform 4m 1,217 m
di-n-Butylphthalate 110m
di-n-Octylphthalate 43 m
Dieldrin 9.5m
Endrin 0.15m
Endrin ketone 0.21 m
Ethylbenz.ene 4,133
Fluoranthene 690m
gamma Chlordane 0.13 m
Note: An RmR after the value indicates it is the maximum concentration detected rather than a 95 percent
UCL.
DENlOO14EFD.WPSIl
7-31
-------
Table 7-3
Subsurface Soil and Landiill Gas Exposure Point Concentrations
Page 2 of2
Landiill Gas Off site
Subsurface Soil RME Landf"ill Gas Onsite Modeled RME
Concentration RME Concentration Concentration
Chemical (mglkg) (JIg/IIi') (JIg/m~
Organics (continued)
gamma-BHC 0.11 m
Methylene chloride 120m 441,718 m
PCB-I260 2,100 m
Phenanthrene 46m
Phenol 95m
Pyrene 75m
Tetrachloroethylene 1.9 m 22.26
Toluene 4m 90,486
Vinyl chloride 438,037 m 0.16
Xylenes 4,997 30.71
Inorganics (Metals)
Aluminum 25,000,000 m
Antimony 30,000 m
Arsenic 18,000 m
Barium 1,200,000 m
Beryllium 2,100 m
Cadmium 3,900 m
Chromium (total) 89,000 m
Cobalt 17,000 m
Copper 97,000 m
Cyanide 2,400 m
Lead 100,000 m
Manganese 18,000,000 m
Mercury 1,100 m
Nickel 29,000 m
Silver 16,000 m
Vanadium 85,000 m
Zinc 180,000 m
Note: An wmw after the value indicates it is the maximum concentration detected rather than a 95 percent
UCL.
DENlOO14EFD.WP5/2
7-32
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Table 7-4
Surface Son Exposure Point Coocentrations for the Page 1 of2
Hypothetical Future Onsite Residential Setting
Group 10 Group 2' Group 3" Group 4d
95 VCL 95 VCL 9S VCL 9S VCL 9S VCL 9S VCL 9S VCL 9S VCL
of the Mean of the Mean of the Mean of the Mean of the Mean of the Mean of the Mean of the Mean
SOU Modeled Dust Soil Modeled Dust Soil Modeled Dust Soil Modeled Dust
Coocentration Concentration Concentration Concentration Coocentration Concentration Concentration Concentration
Chemical (pglkg) (pg/m3) (pglkg) (pg/m3) (pglkg) (pg/m3) (pglkg) (pg/m')
2,3,7,8-TCDD 0.057 e 0.OOOOOOOO9 0.11 e 0.OOOOOOOO28
2-Bulanone 1m 0.00000oo25
bis(2-ethylhexy1)Phthalate 586.63 0.000015 424 0.000011 215 m 0.0000054
Carbon disulfide 6.53 0.000000 16
Chlorofonn 1.05 0.OOOOOOOO26 3m 0.00000oo75 2m 0.00000oo5
PCB. 1260 633.86 0.000016
Toluene 3.84 0.00000oo98 3m 0.00000oo75
Aluminum 16,000,000 NC 19,000,000 NC 170,000,000 NC 25,000,000 NC
Arsenic 9,200 0.00023 7,300 0.00018 12,000 0.0003 4,800 0.00012
Barium 510,000 0.013 240,000 0.006 260,000 0.0064 330,000 0.0078
Beryllium 2,300 0.000057 1,500 0.000038 1,200 0.00003 1,200 0.00003
Cadmium 5,000 0.00012 3,000 0.000075 1,500 0.000038
Chromium (tolal) 1,600 0.0021 62,000 0.0016 16,000 0.00041 27,000 0.00066
Cobalt 21,000 NC 11 ,000 NC 8,900 NC 11,000 NC
Copper 110,000 NC 83,000 NC 21,000 NC 36,000 NC
Cyanide 85,000 0.000039 1,800 0.000045
'Group 1 consists of data from the sewage sludge application/leachate injection area.
"Group 2 consists of data from the sewage sludge application area.
"Group 3 consists of data from the leachate spraying area.
dQroup 4 consists of data from the tire pile area.
"2,3,7,8 TCDD equivalents.
Notes: NC = Indicates a dust concentration was not calculated.
The notation Om" next to the concentration indicates a maximum value used for the RME. All other values reported are 95 VCL of the mean.
Blanks indicate chemical was not detected in the soil goruping.
DEN 1 ooI4EFE.WP5
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Table 7-4
Surface SOU Exposure Point Concentrations for the
Hypothetical Future Onslte Residential Setting Page 2 of2
Group I" Group 2' Group 3' Group 4'
95 VCL 115VCL !IS VCL 95 VCL !IS VCL 95 VCL !IS VCL 95 VCL
of the Mean of the Mean of the Mean of the Mean of the Mean of the Mean of the Mean of the M.ean
Soli Modeled Dust Soli Modeled Dust Soli Modeled Dust Soli Modeled Dust
Concentration Concentration Concentration Concentration Concentration Concentration Cooceotration Cooceotration
Chemical (pg/kg) (pg/mJ) (pg/kg) (pg/mJ) (pg/kg) (pg/mJ) (pg/kg) (pg/mJ)
Lead 670,000 0.0024 80,000 0.002 35,000 0.00086 30,000 0.00075
Mangancse 97,000 0.017 2,300,000 0.057 580,000 0.015 1,900,000 0.045
Mcrcury 880 0.000022 500 0.000013 200 0.000005 100 0.0000026
Nickel 42,000 0.0011 29,000 0.00072 16,000 0.0004 19,000 0.00048
Silvcr 9,400 0.00023 5,000 0.00013
Vanadium 6,3000 0.0016 39,000 0.00097 34,000 0.00084 62 0.0016
Zinc 200,000 0.005 160,000 0.0039 62,000 0.0016 87,000 0.0022
"Group 1 consists of data from the sewage sludge application/lcachatc injection area.
bGroup 2 consists of data from the sewage sludge application area.
"Group 3 consists of data from the Icachate spraying area.
'Group 4 consists of data from the tire pile area.
'2,3,7,8 TCDD equivalents.
Notes: NC = Indicates a dust concentration was not calculated.
Tbe notation "m" next to the concentration indicates a maximum value used for the RME. All other values reported are 95 VCL of the mean.
Blanks indicate chcmical was not detected in the soil goruping.
DEN1.0014E.FE.VYPS
-------
Table 7 -S
Swface Water and Sediment Exposure Point
Concentrations for the Hypothetical
Future Onsite Residential Setting Page 1 of 2
9S UCL of the Mean 9S UCL of the Mean
Swface Waur Sedimentb
Concentration Concentration
Chemical (pg/l) (pglkg)
Organics
1, I-Dichloroethane 15,000
1, I-Dichloroethene 5,000 1,800
1,2-Dichloroethene 730
1,1 , I-Trichloroethane 31,000 110,000
2,4-Dichlorophenol 170 710
2,4-Dimethylphenol 920
2-Butanone 51,000 15,000
2-Hexanone 7,400
2-Methylnaphthalene 9.0 2,100
2-Methylphenol 2,700
2,3,7,8-TCDDc 0.0033
4-Methylphenol 6,600
4-Methyl-2-pentanone 27,000
Acetone 240,000
Aniline 330
Benzene 180 4,700
bis(2-ethylhexyl)phthalate 11,000
Ethylbenzene 340 95,000
Fluoranthene 940
Methylene chloride 7,700
PCB-I260 550
Phenanthrene 0.74 910
Phenol 4,100
Tetrachloroethene 2,300 48,000
Toluene 28,000 280,000
trans-l,2-Dichloroethene 56,000
Trichloroethene 2,500
.Surface water data in unnamed creek from the toe of the landfill to Pond 3 in Section 6.
1>Sediment data in unnamed creek from the toe of the landfill to Pond 3 in Section 6.
Note: The notation "m- next to the concentration indicates a maximum value used for the RME. All
other values reported are 95 UCL of the mean.
DEN 1 001 4EFF.WP5/1
7-35
-------
Table 7-5
Surface Water and Sediment Exposure Point
Concentrations for the Hypothetical
Future Onsite Residential Setting Page 2 of2
95 UCL of the Mean 95 UCL of the Mean
Surface Water" Sedimenf'
Concentration Concentration
Chemical (pg/l) (pg/kg)
Organics (continued)
Vinyl chloride 9,600 19
Xylenes 9,700 580,000
Inorganics (Metals)
Aluminum 110,000 15,000,000
Antimony 40 29,000
Arsenic 24 21,000
Barium 420 430,000
Beryllium 980
Cadmium 2,400
Chromium (total) 33 59,000
Cobalt 51 12,000
Copper 43 46,000
Cyanide 20 650
Fluoride 660
Lead 59 700,000
Manganese 24,000 1,100,000
Mercury 1,000
Nickel 17,000
Vanadium 120 44,000
Zinc 130,000
.Surface water data in unnamed creek from the toe of the landfill to Pond 3 in Section 6.
"Sediment data in unnamed creek from the toe of the landfill to Pond 3 in Section 6.
Note: The notation "mW next to the concentration indicates a maximum value used for the RME. All
other values reported are 95 UCL of the mean.
DENlOOI4EFF.WP512
7-36
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Table 7-6
RME Exposure Paramecen Page I orl
Exposure Inlak. Exposure Exposure Body
Scenario Expo5ure Roule Age' Rale Volts R.renD
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Table 7-6
RME Exposure Parameters Page 1 oU
Exposure Intake Exposure Exposure Body
Scenario Exposure Roule Age' Rate Val.. Rele......e Freq1H!DCY Val.. Commeob Rele......e Duradon Unib Rele......e Welghl Val.. Rele......e
(Receplor in Seclion J I) c: 1-6 100 .."/day OSWU' 60 ~ayolyr 4 dayolwk. at 11 wk.olyr (Iummer) + SS 6 yean OSWU' IS kg OSWU'
1 dlyolwk al 6 wb/yr (",ring/'all)
Ambienl air Inhalalion A: 19-70 10 ~/day OSWER' 60 dayolyr 4 dayolwk. al 11 wk.olyr (Iummer) + SS JO yeaR RAOS' 70 kg EPA VIII'
(Oa.eou. emillion.) 1 dayolwk at 6 wkolyr (opringlrall)
c: 1-18 14 m'/day IPOD' 60 daYl/yr 4 dayolwk. at 11 wb/yr (Iummar) + ss IS yea... EPA VIII' JJ kg IPOD'
1 dayolwk. al 6 wb/yr (opringlrall)
'A = adult and C CI child.
"The re.idential expo.ure value w.. con.idered applicable 10 Ibe corresponding Recrealional or Occupalional..nlng.
~ellonable upperbound value bllcd on .c:onacrYative8 activity and -averago. inhal,don nln.
"'aluel ara average a' three age group I defined by IPOD .. followo:
Im'ldol} A- Body Iapolur.
Inhllallon ktlt Wtlahl Durw.Uon
A...r...w J!!!!IL. Mu:lmurn J!IL ...ImL
I" S , 14 4
5-11 10 12 29 1
~ 12 2! II 1
A~Np""lu& II 14 n 6
Reference Cilcd:
EFH = USEPA 1989. Expo.ure Faclora Handbook. Final Report.
EPA VIII = EPA Region VIR Draft Inlake Allumpliona.
IPOD = Clemenl Alloelale.. Inc. 1988. Mullipalbway Heallb Rilk AI....meni Inpul P.rame\era Ouldance Documen\.
OSWER = USEPA 1991. Hum.n Heallb Ev.lu'lion Manu.I, Supplemenlal Ouid.nce; Sland.rd Default Expoluro Faclora.
RAOS = USEPA 1989. Rilk "...lmenI8uldance for Superfund, Human h..11b ev.luaUon manual. P.rt".
S5 = Expolure v.lue. are b..ed on .ite.specific condilion. .nd pro'e..ionaljudgmenl. Seelext 'or full explanation.
EPA. 1986 = Draft Superfund Expo.ure A..e..menl Manual, Rgudlng dull .uppro..ion when precipilation exceed. 0.01 Inch.
D£NI0014FOO.WP5
-------
Table 7-7
Toxicity Values for Chemicals with Can:iaogeoic Effects" Page 1 of2
OraJ IDbalation
U.s. EPA Cancer sr sr
Chemical n.-;f;r..tion (mgIkg-day).1 Ref' (mgIkg-day)"1 Ref'
Organics
1, l-Dichloroethane C IRIS 1217/89
1, l-Dichloroethylenc C 0.6 IRIS 1/1/91 0.175 IRIS 1/1/91
1,2-Dichloroethane B2 0.091 IRIS 1/1/91 0.091 IRIS 1/1/91
1,1,2- Trichloroethane C 0.057 IRIS 1/1/91
1,1 ,2,2-Tetrachloroethane C 0.2 IRIS 1/1/91
2,3,7,8-TCDD B2 156,000 HEAST 1/91 150,000 HEAST 1/92
150,000" HEAST 1/92 (oral)
2-Methylphenol C IRIS 8/1/91
4,4'-DDD 0.24
4,4'-DDE 0.034
4,4'-DDT B2 0.3395 IRIS 1/1/91 0.34 IRIS 1/1/91
Aldrin 17 17.15
Aniline B2 0.0057 IRIS 6/1/89
Benzene A 0.029 IRIS 1/1/91 0.029 IRIS 1/1/91
BeDZO(a)aDlhracene B2 11.5 HEAST 1/91
Benzo(b )tIuoranthene 7.3
Beta-BHC 1.8 1.855
bis(2-chloroethy1)ether B2 1.1 BEAST 1/91
bis(2-ethylhexyl)phthalate B2 0.014 IRIS 5/1/90
IRIS 8/1/914
Carbon tetrachloride B2 0.13 IRIS 1/1/91
Chloroform B2 00061 IRIS 1/1/91 0.0805 IRIS 1/1/91
Dieldrin 16 16.1
Ethylene dibromide B2 8585 IRIS 1/1/91
Gamma-BHC 1.3
Methyleoe chloride B2 0.0075 IRIS 9/1/90 0.00165 IRIS 1/1/90
PCB-1260 B2 7.7 IRIS 1/9/90
Pentachlorophenol B2 0.12 IRIS 3/1/91
Tetrachloroethylene B2 0.051 IRIS 6/1/90 0.00182 HEAST 1/91
HEAST 1/914
trans-l ,3-Dichloropropeoe B2 IRIS 1/1/91
Trichloroethylene B2 0.011 IRIS 6/1/90 0.006 HEAST 1/91
Vmyl chloride A 1.9 HEAST 1/91 0.3 BEAST 1/92
'Only those chemicals classified as an A, BI, B2, or C carcinogen are listed on this table.
"sF = Slope factor.
"Ref = Reference, citation and date of toxicity value.
'Value and date used for OUs 2&3 and 4&5 if different than that used for OUs 1&6.
DEN10014F01.WP5/1
7-39
-------
Table 7-7
Toxicity Values for Chemicals with Carcinogeaic Effects" Page 2 012
Oral Iahalation
v.s. EPA CaDcer sr sr
Chemical CJ.....a&-..tion (mg/kg-day)"1 ReI" (mglkg-day).1 Ref"
Inorganics (Metals)
Arsenic A 1.75 IR.IS 9/1/91 15.05 IRIS 1/13/88
Beryllium 82 4.3 IRIS 1/1/91 8.4 IRIS 1/1/91
Cadmium 81 (mhalation) 6.3 IRIS 1/1/91
Chromium (IV) A (mhalation) IR.IS 3/1/91 42 IRIS 3/1/91
Lead 82 IRIS 5/1/91
'Only those chemicals classified as an A. 81, 82, or C carcinogen are listed on this table.
'SF = Slope factor.
"Ref = Reference, citation and date of toxicity value.
4Value and date used for OUs 2&3 and 4&5 if different than that used for OUs 1&6.
DEN10014F01.WP512
7-40
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-
Table 7-8 Page 1 of 4
Toxicity Values for Chemicals with Noncarcinogenic Effects"
Oral Inhalation
Reference Reference
Dose (RID) Confidencel Dose (RID) Confidence!
Chemical (mg/kg/day) UIM Fadon~ Health Effects Reference" (mg/kg/day) UIM Facton~ Health Effects Reference.
Organics
I, I-Dichloroethane 0.1 --/100/- None obselVed HEAST 1/92 0.143 -/1000/- Kidney damage HEAST 1/92
I,I-Dichloroethylene 0.009 M/looo/l Hepatic lesions IRIS 1/1/91
1 ,2-Dichloroethene 0.02 Ulooo/l Liver lesions IRIS 1/1189
0.009" -/1000'/-- HEAST 1/9~
1,1, I-Trichloroethane 0.09 -/1000/- Hepatotoxicity HEAST 1/92 0.286 -/1000/- Hepatotoxicity HEAST 1/92
1,1,2- Trichloroethane 0.004 MI I 0001 I IRIS 1/1/91
1 ,2,4-Trichlorobenzene 0.0013 --/1000/- HEAST 8/1/90
2,4-Dichlorophenol 0.003 Uloo/l Decreased delayed IRIS 8/1/89
hyper-sensitivity
2,4-Dimethylphenol 0.02 U3000/l Lethargy, heme IRIS 11/1/90
2,4-Dinitrophenol 0.002 Ulooo/l IRIS 3/1/90
2-Butanone (MEK) O.OS. -/1000/-. IRIS 8/1191 0.286 Ul000/3 Decreased fetal IRIS 7/1/9
birth weight
2-Chlorophenol O.OOS 1/1 000/1 IRIS 811/89
2-Methylphenol O.OS M/I 0001 1 Decreased body IRIS 9/1/90
weight, neurotoxicity
4,4'-DDT O.OOOS M/loo/l Liver lesions IRIS 9130187
4-Chloroaniline 0.004
4-Methylphenol O.OS --/1000/- DeclUsed body HEAST 1/92
weight, neurotoxicity
4-Methyl-2-pentanone O.OS --/1000/- Liver and kidney HEAST 1/92 0.0229 -/1000/- Liver and kidney HEAST 1/92
effects
"Only those chemicals with an RID or a pending Rt-D are listed on this table.
"Confidence is the level of confidence in the RID and is given aa L for low, M for medium, snd H for high. UIM is the uncertainty and modifying factors used to derived the RID,
the uncertainty factor is the middle value and the modifying factor is the last value given.
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Table 7-8
Toxicity Values for Chemicals with Noncarcinogenic Effect&" Page 2 of 4
Oral Inhalation
Reference Reference
Dose (RID) Confidence/ Dose (RID) Confidence!
Chemical (maika/day) UIM Facton' Health Effects Referenclf (mglka/day) UIM Facton' Health Effects Reference.
Ol'(lanics (continued)
Acetone 0.1 UlOOO/1 Neurotoxicity, IRIS 12/1190
increased liver and
kidney weight
Aldrin 0.00003
Aniline 0.()00286 U3OOO/l Spleen toxicity IRIS 1111191
Benzene
Benzoic acid 4
bis(2-ethylhexl)phthalate 0.02 M/looo/l Increased liver IRIS 5/1191
Butylbenzyl phthalate 0.2
Carbon disulfide 0.1 Mil 0011 Fetal toxicity, IRIS 9/1190
malfonnations
Carbon tetrachloride 0.0007 M/looo/l IRIS 1/1/91
Chlorofonn 0.01 M/looo/l IRIS 111191
Di-n-butylphthalate 0.1
Dieldrin 0.00005
Endrin 0.0003 M/IOO/1 Mild liver lesions, IRIS 411191
occasional contusions
Gamma-BHC 0.0003
Methylene chloride 0.06 Mil 0011 Liver toxicity IRIS 311188
Naphthalene 0.004 -/10000/-- - IRIS 12/1/90
Pentachlorophenol 0.03 M/IOO/1 - IRIS 311190
Phenol 0.6 Ul00/l Decreased fetal IRIS 2/1/90
'Only those chemicals with an RID or a pending Rt-D are listed on this table.
bConfidence ia the level of confidence in the RID and Is given as L for low, M for medium, and H for high. UIM is the uncertainty and modifying factors used to derived the RID,
the uncertainty factor is the middle value and the modifying factor ia the l88t value given.
"Ref = Reference, citation and date oftoxicity value.
4Value and date used for OUa 2/3 and 4/5 if different than that used for OUa 116.
"No toxicity value was used for OUs 2/3 and 4/5.
I'RID is pending.
DEN1001.4F02.:VVPS
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Table 7-8
Toxicity Values lor Chemicals with NODClI1'Clnogeoic Effects" Page 3 of 4
Oral lohalation
Reference Reference
Dose (RID) Conlldencel Dose (RID) Conlldeucel
Chemical (malka/day) VIM Factors~ Health Effects Referenclf (mglkg/day) VIM Factors~ Health Effects Reference"
Ol'lanics (continued)
Pyrene 0.03
Tetrachloroethylene 0.01 Mil 0001 1 Hepatotoxicity, weight IRIS 6/1/90
gain
Toluene 0.2 MIl 00011 Changes in liver and IRIS 8/1190 0.114 -/300/- Neurological HEAST 1/92
kidney weight effects
trans-l,2-Dichloroethene 0.02 Ulooo/l -- IRIS 1/1189
trans-l,3-Dichloropropene 0.0003 Ul0000/l -- IRIS 111/91
Trichloroethylene --
Xylenes 2 M/lOO/1 HS peractivity, IRIS 9/30/87
decreased body weight
Inol'lanics (Metals)
Antimony 0.0004 UlOOO/1 Decreased longevity, IRIS 8/1/89
increased blood
cholesterol
Arsenic 0.0003 M/3/1 Hyperpigmentation, IRIS 9/1/9
vascular complications
Barium 0.07 M/3/1 Increased blood IRIS 8/1/90 0.000143 -/1000/- Fetotoxicity
pressure
Beryllium 0.005 UlOOIl None observed IRIS 9/1190
Cadmium 0.0005 H/I0/1 Proteinuria IRIS 10/1/89
Chromium (IV) 0.005 U5OO/1 None observed IRIS 3/1/88
"Only those chemicals with an RID or a pending Rt-D are listed on this table.
'Confidence is the level of confidence in the RID and is given as L for low, M for medium, and H for high. UIM is the uncertainty and modifying factors used to derived the RID,
the uncertainty factor is the middle value and the modifying factor is the last value given.
"Ref - Reference, citation and date of toxicity value.
dValue and dale used for OUs 2/3 and 4/5 if different than that used for OUs 116.
"No toxicity value was used for OUs 2/3 and 4/5.
raID is pending.
DEN10014F02.WP5
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Table 7.8
Toxicity Values for Chemkals with Noncarclnogeoic Effecb" Page 4 of 4
Oral Inhalation
Reference Reference
Dose (RID) Confidence! Dose (RID) Confidence!
Chemical (mglka/day) VIM Facton' Health Effects Reference' (mglkglday) VIM Facton' Health Effects Reference'
lDorganics (MetaJs) (continued)
Cyanide 0.02 MIl 0015 Weight loss, thyroid IRIS 3/1191
effects, myelin
degeneration
Manganese 0.14 MllIl CNS effects IRIS 12/1190 0.00014 Ml300/3 Increased IRIS 1211190
prevalence of
respiratory
symptoms,
psychomotor
disturbances
Mercury 0.0003 --/1000/- Kidney effects HEAST 1191 0.0000857 -1301- Neurotoxicity
Nickel 0.02 -/300/- Decreased body wightl HEAST 1192
organ weight ,
Silver 0.005 U3/1 Argyria IRIS 12/1191
Thallium 0.00007 -/3000/- - HEAST 1191
Vanadium 0.007 -1100/- None observed HEAST 1192
Zinc 0.2 -110/- Anemia HEAST 9/30/87
'Only those chemicals with an RID or a pending Rt-D are listed on this table.
'Confidence is the level of confidence in the RID and is given 89 L for low, M for medium, and H for high. UIM is the uncertainty and moditying factors used to derived the RID,
the uncertainty factor is the middle value and the modi tying factor is the last value given.
-------
",~.
I Table 7-9 I
coes Without Toxicity Values
OUs 1/6 OUs213 OUs 4/5
Subsurface Subsurface Landfill Surface Surface
Chemical LiquicJs& Soil Gas Soil Water Sediment
Organics
1, I-Dichloroethane X X X
1 ,4-Dichlorobenzene X
2-Hexanone X X
2-Methylnaphthalene X X X
Benzyl alcohol X
Carbazole X
Chloroethane X
di-n-octylphthalate X X
Dibenzofunm X
Endrin ketone X
Phenanthrene X X X
Inorganics (Metals)
Aluminum X X X X
Cobalt X X X X X
Copper X X X X
Fluoride X
Lead X X X X X
'Subsurface liquids consist of shallow ground water, waste-pit liquids, and deep ground water.
Note: An X indicates the medium the chemical was detected in.
l0014F03.DEN/l
7-45
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Table 7-10
Sununary of Quantified Site Risks Based on Hypothetical Future Onsite Residential Setting Page 1 of 3
Reasonable Maximum Exposure
Excess Lifetime Noncancer Hazard
Exposure Pathways" Chemicals of Concern Cancer Risk Quotient
Organics
Ingestion of subsurface liquids as a drinking water sourceb Benzo( a)anthracene 2 X 1003 NA
Arsenic 2 X 1003 10
Vinyl chloride 2 X 10.3 NA
2,3,7,8-TCDDc 1 X 1003 NA
1.2-Dichloroethane 6 X 1
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Table 7-10 Page 3 of 3
Summary of Quantified Site Risks Based on Hypothetical Future Onsite Residential Setting
Reasonable Maximwn Exposure
Excess Lifetime Noncaneer Hazard
Exposure Pathways" Chemicals of Concern Cancer Risk Quotient
Organics (continued)
Surface Water Ingestion as a Child I ,I ,I-trichloroethane NC 0.075
Manganese NC 0.05
Pathway Totald 8 x 10'" 2
Inorganics (Metals)
Sediment Ingestion as a Child Arsenic 7 x 10-6 0.15
Antimony NC 0.16
Chromium NC 0.03
Manganese NC 0.03
Pathway Totald 9 x 10-6 0.4
Maximwn Cwnulative Total 2 x 10.2 49
"Exposure pathways presented are for adults using reasonable maximum exposures (RMEs).
bSubsurface liquids consist of shal10w ground-water, waste-pit liquids, and deep ground water from source area wells.
cDioxin equivalents.
dNot al1 COCs that contribute to the total risk are listed, therefore, sum of risk (or HQs) for listed chemicals will not equal the total.
°Using Group I exposure point concentrations.
"Dust arising form Group I surface soit.
'As hexavalent chromium.
NC = Not carcinogenic through this pathway.
NA = Not applicable.
DENlOO1 4F04.WPS
-------
t
...,J
Table 7-10
Summary of Quantified Site Risks Based on Hypothetical Future Onsite Residential Setting Page 2 of 3
Reasonable Maximum Exposure
Excess Lifetime Noncancer Hazard
Exposure PathwayS- Chemicals of Concern Cancer Risk Quotient
Organics (continued)
Surface Soil Ingestion- 2,3,7,8-TCDD 4 X l~ NA
PCB-1260 2 X l~ NA
Chromium NC 0.02
Pathway Totald 2 X 10-& 0.1
Particulate Inhalatioa Chromium' 1 X 10" NA
Manganese NC 0.04
Barium NC 0.02
Pathway Totald 1 X 10-& 0.06
Surface Water Ingestion as a Child Vinyl chloride 7 X 10-' NA
l,l-Dichloroethene 1 X 10.4 0.12
2,3,7,8-1rCDDc 2 X 10" NA
trans-l ,2- Dichloroethene NC 0.61
Acetone NC 0.52
4-Methyl-2-pentanone NC 0.12
.Exposure pathways presented are for adults using reasonable maximum exposures (RMEs).
bSubsurface liquids consist of shallow ground-water, waste-pit liquids, and deep ground water from source area wells.
cDioxin equivalents.
dNot all COCs that contribute to the total risk are listed, therefore, sum of risk (or HQs) for listed chemicals will not equal the total.
-Using Group 1 exposure point concentrations.
fJ)ust arising form Group 1 surface soil.
CAs hexavalent chromium.
NC = Not carcinogenic through this pathway.
NA = Not applicable.
DBN1001.4F04."NPS
-------
Table '-11
Comparison of Subsurface Soil Maximum Detected Concentrations
to Carcinogenic Risk-SpeclilC Values and Noncarcinogenic
Reference Concentrations in the Future Onsite Residential Setting Page 1 of 2
Reasonable Maximum Exposure'
Maximum Risk-SpeclilC Exceeds Reference Exceeds
Det«ted V alueb Risk-SpeclilC Concentrationb Reference
Chemical Concentration (pgIkg) Value? (pgIkg) Concentration?
1,1,1- Trichloroethane 3.9 NA - 7,029,702 No
1,2-Dichloroethane 130 6,986 No NA -
2-Butanone 6,700 NA - 31,923 ,383 ,879 No
4,4'-DDD 1.2 2,654 No NA -
4,4'-DDE 0.11 1,873 No NA -
4,4'-DDT 30 1,870 No 39,063 No
4-Chloroaniline 2,500 NA - 312,500 No
4-Methyl-2-pentanone 540 NA - 3,900,284 No
Acetone 15,000 NA - 7,821,500 No
Aldrin 3.7 37 No 2,344 No
Aluminum 24,700,000 NA - NA -
Antimony 30,000 NA - 31,250 No
Arsenic 18,000 358 Yes 23,438 No
Barium 1,190,000 NA - 4,073,201 No
Benzene 1 21,922 No NA -
Benzo(b )fl.uoranthene 52 87 No NA -
Benzoic acid 210 NA - 312,500,000 No
Beryllium 2,100 148 Yes 390,625 No
Beta-BHC 6 353 No NA -
Butylbenzylphthalate 170 NA - 15,625,000 No
Cadmium 3,900 53,990 No 39,063 No
Chloroform 4 101,899 No 781,250 No
Chromium (Total) 83,000 8,098 Yes 390,625 No
Cobalt 17,000 NA - NA -
Copper 97,000 NA - NA -
Cyanide 2,400 NA - 1,562,500 No
Di-n-butylphthalate 110 NA - 7,812,500 No
Di-n-octylphthalate 62 NA - NA No
Dieldrin 9.5 40 No 3,906 No
Endrin 0.15 NA - 23,438 No
Endrin Ketone 0.21 NA - NA -
"Reasonable maximum exposure parameters and maximum detected concentrations.
bRisk-specific values and reference concentrations assume ingestion of soil and inhalation of airborne
contaminants adsorbed to dust.
Note; NA = No toxicity values with which to calculate a value.
- = Not applicable.
DEN 1001 4FOS.WPS/I
7-49
-------
Table 7-11
Comparison of Subsurface Soil Maximum Detected Concentrations
to Carcinogenic Risk-SpecifIC Values and Noncarcinogenic
Reference ConcentratioDS in the Future Oosite Residential Setting Page 2 of 2
Reasonable Maxhnum Exposur~
Maximum Risk-SpecifIC Exceeds Reference Exceeds
Detected Valueb Risk-SpecifIC Cooceotrationb Reference
ChenUcal Concentration (pgIkg) Value? (pgIkg) Concentration?
Fluoranthene 69 NA - 3,125,000 No
Gamma chlordane 0.13 NA - NA -
Gamma-BHC (Lindane) 0.11 490 No 23,438 No
Lead 101,000 NA - NA -
Manganese 1,770,000 NA - 4,847,016 No
Mercury 1,100 NA - 23,380 No
Methylene chloride 120 84,891 No 4,687,500 No
Nickel 29,000 NA - 1,562,500 No
PCB-I260 (Aroclor 1260) 2,100 83 Yes NA -
Phenanthrene 46 NA - NA -
Phenol 9S NA - 46,875,000 No
Pyrene 7S NA - 2,343,750 No
Silver 16,000 NA - 390,625 No
Tetrachloroethene 1.9 12,488 No 781,250 No
Toluene 4 NA - 15,605,904 No
Vanadium 85,000 NA - 546,875 No
Zinc 179,000 NA - 15,625,000 No
bis(2-Ethylhexyl) phthalate 1,800 45,496 No 1,562,500 No
"Reasonable maximum exposure parameters and maximum detected concentrations.
bRisk-specific values and reference concentrations assume ingestion of soil and inhalation of airborne
contaminants adsorbed to dust.
Note: NA = No toxicity values with which to calculate a value.
- = Not applicable.
DENlOO14F05.WP5n
7-50
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Table 7-12
Com~n of Exposure Point Concentrations of Landfill Gas Within
the Landfill Mass to Carcinogenic Risk-SpeeulC Values and Noncarcinogenic
Reference Concentrations in the Future Onsae Residential Setting i
Reasonable Maximum Expossure"
95 UCL Gas Risk-Specif"1C Exceeds Reference Exceeds
Concentration Value Risk-Specif"1C Concentration Reference
Chemical (pgIm3) (pgIm3) Value? (pgIm3) Concentration?
1,1, I-Trichloroethane 3.7 x 1Q4 NA - 1,043 Yes
1,1-Dichloroethane 1.3 x 105 (M) NA - 521 Yes
1,1-Dichloroethcne 8.7 x 103 0.05 Yes NA -
1,2-Dichloroethane 1.5 x 103 (M) 0.09 Yes NA -
2-Butanone 3.8 x 1Q4 (M) NA - 1,043 Yes
Benzene 1.3 x 1Q4 0.29 Yes NA -
CaJbon disulfide 2.2 x 1Q4 NA - NA -
Chlorofonn 1.2 x 103 (M) 0.11 Yes NA -
Ethylbcnzcne 4.1 x 103 NA - 1,043 Yes
Methylene chloride 4.4 x 105 (M) 5.18 Yes NA -
Toluene 9.0 x 1Q4 NA - 417 Yes
Xylenes 5.0 x 103 NA - NA -
Vinyl chloride 4.4 x 105 0.03 Yes NA -
&RME uses reasonable maximum exposure parameters and 95 UCL concentrations.
Notes: (M) = Maximum concentration used; 95 UCL exceeds maximum concentration.
NA = NO..inha1ation toxicity value with which to calculate a value.
lOO14F03.DENI2
7-51
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Table 7-13
Comparison' of Modeled Exposure Point Concentrations Assmning a Cracked Slab to Carcinogenic
Risk-Specific Values and Noncarcinogenic Reference Concentrations in the Future Offsite
Residential Setting
Reasonable Maximmn Exposure"
Modeled Gas Risk-Specific Exceeds Reference Exceeds
Concentration Value Risk-Speclfic Concentration Reference
Chemical (pg/m3) (p.g/m3) Value? (pg/m3) Concentration?
1,1, I-Trichloroethane 3.6 NA - 1,043 No
1,I-Dichloroethene 1.2 0.05 Yes NA -
Vinyl chloride 31.0 0.03 Yes NA -
8RME uses reasonable maximum exposure parameters and 95 UCL modeled gas concentrations.
Notes:
NA = No inhalation toxicity values with which to calculate a value.
- = Not applicable.
l0014F03.DENI3
7-52
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Table 7-14
Cmnulative Total Risk for the
Hypothetical Future Onsite Residential Setting
R.easonable Maximum Exposure
Exposure MedialExposure Excess Lifetime
Pathway Cancer Risk Noncancer m
Ground Water
Ingestion 1 X 1002 47
Surface Soil
Ingestion 2 X 10.5 0.1
Inhalation 1 X 1005 0.06
Surface Water
Ingestion 8 X 10"' 2
Sediments
Ingestion 9 X 1()'6 0.4
Cmnulative Total 2 X 10"2 49
lOO14F03.DEN/4
7-53
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Table 7-15
Default Parameters Used in UptakelBiokinetic Model
Dust/Soil
Time Spent Ventilation Dietary Lead Water Ingestion
Age Group Outdoors Rate Uptake Comumption Rate
(yrs) (hr/day) (m3/day) (pg/day) (L/day) (mg/day)
0.5 - 1 1.0 2.0 5.88 0.20 100
1 -2 2.0 3.0 5.92 0.50 100
2-3 3.0 5.0 6.79 0.52 100
3-4 4.0 5.0 6.57 0.53 100
4-5 4.0 5.0 6.36 0.55 100
5-6 4.0 7.0 6.75 0.58 100
6-7 4.0 7.0 7.48 0.59 100
Notes: Additional assumptions used for all age groups:
(1) Indoor air concentration of Pb = 30 percent of outdoor air concentration of Pb.
(2) Lung absorption: 32 percent of inhaled Pb is absorbed by respiratory tract.
(3) Nonlinear gastrointestinal tract absorption method was used for all model runs.
(4) Fraction of household dust derived from soil = 0.28 JLgPb/g dust per JLgPb/g soil.
(5) Concentration of Pb in indoor dust derived from air = 100 JLgPb/g dust per JLgPb/g
au.
(6) Pb in indoor dust derived from soil and airborne particulates only.
(7) Percent of soil/dust that is soil = 45 percent.
(8) Mother's blood Pb level at birth of child = 7.50 JLg/dL.
% = Percent
hr/day = hour(s) per day
rri31 day = cubic meter(s) per day
JLg/dL = microgram(s) per deciliter
Llday = liter(s) per day
Pb = Lead
yr(s) = year(s)
mg/day = milligram(s) per day
p.g/day = microgram(s) per day
l0014F03.DEN/S
7-54
-------
Table 7-16
Risk Assessment Radionuclides
OUs 1/6 OUs 2/3 OUs 4/5
Subsurface Subsurface Landfill Surface Surface
Radionuclide Liquids' Soil Gas Soil Water Sediment
Americium-241 X
Cadmium-1OO X
Cesium-137 X X
Europium-159 X
Lead-210 X X
Plutonium-239 X X X
Potassium-40 X X X X
Radium-226 X X X
Strontium-90 X X X
Thorium-228 X X X
Thorium-230 X X
Thorium-232 X X X X
Tritium X X
Uranium-234 X X X X X
Uranium-235 X X X X
Uranium-238 X X X X X
lOO14F03.DEN/6
7-55
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Table 7-17
Summary of Radiological Risk from Ingestion of Ground Water at the RME
Future Omite Residential Setting
9S UCL Concentration Excess Cancer Risk
Onsite" Upgradient
Radionuclide (pCi/L) (pCi/L) Onsite Upgradient
Potassium-40 462 97 1.1 X 10"" 2.2 X 10-5
Lead-210 11M NA 1.5 X 10"" -
Radium-226 75 50 (M) 1.9 X 10"" 1.3 X 10""
Uranium-234 49 (M) 2.2 (M) 1.6 X 10-5 7.4 X 10-7
Uranium-235 18 (M) 20 (M) 6.0 X 1~ 6.6 X 10-6
Uranium-238 73 (M) 5.2 (M) 4.3 X 10-5 3.1 X 1~
Total S X 10" 2 X 10"
.Shallow ground-water wells and waste pit liquids well point within the source area.
(M) = Maximum concentration used as 95 UCL exceeds maximum concentrations or insufficient data
to calculate a 95 UCL.
NA = Not available.
lOO14F03.DENn
7-56
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Table 7-18
Comparison of Maximmn Detected Subsurface Soil Concentrations
to Carcinogenic Risk-Specific Values at the RME for the Future Onsite Residential Setting
Reasonable Maximum Exposure
Onsite Background
Risk- Maximmn Exceeds Maximum Exceeds
Specific Detected Risk- Detected Risk-
Value- Concentration Specific Concentration Specific
Radionudide (pCi/g) (pCi/g) Value? (pCi/g) Value?
Potassium-40 0.064 27 Yes 21 Yes
Lead-210 0.79 1.8 Yes NA -
Plutonium-239 1.6 0.4 No NA -
Strontium-90 14.6 0.2 No NA -
Thorium-230 5.6 2.1 No NA -
Thorium-232 5.9 1.7 No NA -
Thorium-228 0.0062 2.2 Yes 2.2 Yes
Uranium-234 5.9 2.9 No NA -
Uranium-238 0.73 1.5 Yes NA -
aRisk-specific values account for internal (ingestion and inhalation) and external exposure and
correspond to a 10-6 excess cancer risk.
NA = Not available.
lOO14F03.DEN/8
7-57
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....J
~
00
Table 7-19
Summary of Radiological Risk from Exposure to Surficial Soif
at the RME Future Onsite Residential Setting
95 VCL Concentration Pathway Specific Exc~ Cancer Risk
Ingestion Inhalation External .
Onsite Background
Radionuclide (pCi/g) (pCi/g) Onsite Background Onsite Background Onsite Background
Cesium-137 0.17 0.23 5.9 x 10.9 8.3 X 10.9 1. 7 X 10"11 2.3 X 10.11 9.7 X 10-6 1.3 X 10-5
Radium-226 2.3 2.8 3.4 x 10.1 4.2 X 10-1 3.6 X 10.8 4.4 X 10.8 3.9 X 10-4 4.8 X 10-4
Uranium-234 1.6 1.2 3.2 x 10-8 2.4 X 10-8 2.2 X 10-1 1.6 X 10-7 1.4 X 10.9 1.0 X 10.9
Uranium-235 0.25 0.3 5.1 x 10-9 6.0 X 10.9 3.3 X 10-8 3.9 X 10.8 1.7 X 10-6 2.1 X 10.(\
Uranium-238 1.6 1.3 5.6 x 10.8 4.6 X 10.8 4.4 X 10.7 3.5 X 10.7 1.7 X 10.(\ 1.3 X 10-6
Total 4 x 10.1 S X 10" 7 X 10" 6 X 10-' 4 x 10-4 S X 10-4
.Surface soil from the sewage sludge based application/leachate injection area (Group 1 soils).
DEN1.001.4F06.v.7PS/1.
-------
-..J
I
VI
\0
Table 7-20
Summary of Radiological Risk from Exposure to Sedimenfs8
at the RME Future Onsite Residential Setting
9S VCL Concentration Pathway Specific Excess Cancer Risk
Ingestion Inhalation External
Onsite Background
Radionuclide (pCi/g) (pCi/g) Onsite Background Onsite Background Onsite Background
Europium-154 0.20 NA 7.6 x 10-10 -- 1.5 X 10-10 -- 2.4 X 10-5 --
Potassium-40 23.0 19.0 3.2 x 10.7 2.7 X 10-7 9.3 X 10-10 7.7 X 10.10 3.6 X 10-4 3.0 X 10-4
Radium-226 2.7 2.1 4.0 x 10-7 3.2 X 10.7 4.2 X 10-8 3.4 X 10.8 4.6 X 10-4 3.7 X 10-4
Thorium-232 1.3 NA 2.0 x 10-8 -- 2.0 X 10-1 -- 9.9 >< 10.10 --
Thorium-228 1.6 1.3 1.1 x 10-7 9.2 X 10-8 6.6 >< 10-1 5.4 X 10.7 2.6 >< 10-4 2.1 X 10-4
Uranium-234 1.5 1.8 3.0 x 10.8 3.6 X 10.8 2.0 X 10-7 2.5 X 10-7 1.3 X 10-9 1.6 X 10-9
Uranium-235 0.077 0.30 1.6 x 10-9 6.0 X 10-9 1.0 X 10-8 3.9 X 10.8 5.3 X 10-1 2.1 X 10-6
Uranium-238 1.5 1.2 5.3 x 10.8 4.2 X 10.8 4.1 X 10.7 3.3 X 10-1 1.6 X 10.6 1. 2 >< 10.6
Total 9 x 10.7 8 X 10.7 2 X 10-<1 1 X 10-<1 1 X 10-3 9 >< 10"
'Sediments from eight sample locations.
DENlOO14F06.WPS/2
-------
Table 7-21
Summary of Radiological Risk at the RME
Future Onsite Residential Setting
Excess Cancer Risk
Exposure Media Exposure Pathway Onsite Background
Ground Water Ingestion 5 x 1()"4 2 x 104
Surface Soil Ingestion 4 x 10-7 5 X 1007
Inhalation 7 x 10-7 6 X 10.7
External 4 x 1()"4 5 x 104
Surface Water Ingestion 2 x 10..7 NA
Sediments Ingestion 9 x 1007 8 X 10-7
Inhalation 2 x 1()"6 1 x 1()"6
External 1 x 10-3 9 x 104
Total Exposure 2 x 10"3 2 X 10-3
}OO}4F03.DEN/9
7-fIJ
-------
Table 7-22
Potentially Occurring Threatened and Endangered
Species Within or Around the Lowry Site
Birds
Peregrine falcon Falco peregrinus
Bald Eagle Haliaeetus leucocephalus
Black tern' Chlidonia niger
Mountain plover" Charadrius man/anus
White-faced ibis" Plegodis chihi
Baird's sparrow" Ammodramus bairdii
Whooping crane Grus americana
Long-billed curlew Numenius omericanus
Ferruginous hawk Buteo regalis
Amphibiam
Western boreal toad' Bufo boreas boreas
Imeds
Regal fritillary butterfly" Speyeria idD.lia
JItfAmm~ls
Preble's meadow jumping mouse Zapus hudsonius preblei
Swift fox' Vulpes velos
Black-footed ferret
Mustela nigripes
Vegetation
Diluvium lady's tressesb Spiranthes diluvialis
Colorado butterfly plant" Gaura neome:xicana ssp, Coloradensis
'Species that are candidates for official listing as threatened or endangered species (Federal
Register, Vol. 54, No.4, January 6, 1989; Vol 55, No. 35, February 21, 1990).
bJisted by USFWS as Category 2, under review for protective status, Final Remedial
Investigation Report for the Shallow Ground Water and Subsurface Liquids and Deep
Groundwater Operable Units, Lowry Landfill, Vol. VI of VDI. Lowry Coalition, Boulder, CO).
"Listed by USFWS as Category 1, under review for protective status with sufficient information
to support proposing to list the taxa as Threatened and Endangered.
lOO14F03.DEN/lO
7-61
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lOOI4F03.DEN/II
Table 7-23
Comtituents Eliminated on the Basis of Relative Toxicity
Comtituent Surface Soil Surface Water Sediments
Bromide X
Calcium X X X
Chloride X X X
Magnesium X X X
Nitrate X X X
Nitrite X
Nitrogen X
Phosphorous X X X
Potassium X X
Sodium X X X
Sulfate X
Sulfur X X X
7-62
-------
Table 7-24
Maxim1D11 Detected Concentrations of
Ecological Chemicals of Concern Page 1 of 2
Surface Soil Surface Water Sediment
Chemical (mg/mg soil) (pgll) (mg/mg sediment)
Organics
1, I-Dichloroethane 15,000 0.0000034
1,I-Dichloroethene 5,000
1 ,2-Dicbloroethene (total) 730 0.00000057
1,1, I-Trichloroethane 31,000 0.00011
2,4-Dichlorophenol 400 0.0000027
2,4-Dimethylphenol 920 0.0000038
2-Butanone 0.OOOOOOOO65 51,000 o. ()()()() 15
2-Hexanone 10,000
2-Methylnaphthalene 400 0.000024
2-Methylphenol 0.0000038
4-Chloroaniline 0.0000025
4-Methylphenol 66,000
4-Methyl-2-pentanone 27,000
Acetone 0.00000014 240,000 0.0000084
Aniline 0.00000033
Benzene 5,000 0.00000061
Benzoic acid 6,300
bis(2-ethylhexyl)phthalate 0.0000022 0.000095
Carbon disulfide 0.00000OO25
Chloroform 0.OOOOOOOO35
di-n-Butylphthalate 0.0000020 4,000 0.0000027
Ethylbenzene 5,000 0.000095
Fluoranthene 0.0000077
Heptachloroodibenzofurans 0.OOOOOOOOO30
Heptachlorodibenzo-p-dioxins 0.OOOOOOOO29 0.OOOOOOOO56
Hexachlorodibenzodioxins 0.OOOOOOOOO30 0.OOOOOOOOO70
Hexachlorodibenzofurans 0.OOOOOOOOO10
Methylene chloride 0.00000015 77,000
Naphthalene 400 0.000014
octochlorodiben.zodioxins 0.00000oo14 0.040 0.OOOOOOOOO60
Octochlorodibenzofurans 0.OOOOOOOOO20
PCB-l260 0.0000076 0.0000024
Pentachlorodibenzodioxins 0.OOOOOOOOO10
I Note: Blanks indicate chemical not of concern in the medium. I
DENlOO14F07.WP5/1
7-63
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Table 7-24
Maximmn Detected Concentrations of
Ecological Chemicals of Concern Page 2 of 2
Surface Soil Surface Water Sediment
Chemical (mg/mg soil) (pgll) (mg/mg sediment)
Organics (continued)
Phenanthrene 0.0000062
Phenol 4,100
Pyrene 0.0000055
Toluene 0.00000oo11 28,000 0.00028
Tetrachloroethene 2,300 0.000048
trans-l,2-Dichloroethene 56,000 0.0000031
Trichloroethene 5,000 O. ()()()()41
Vinyl chloride 9,600 0.0000012
Xylenes 9,700 0.00058
Inorganics (Metals)
Aluminum 0.027 260,000 0.032
Ammonia 0.0000032 25,000 O.OOOOSI
Antimony 150 0.000032
Arsenic o. {)()()() 14 42 0.000021
Barium 0.0016 1,500 0.00086
Beryllium 130,000 0.0000027
Boron 240
Cadmium O. {)()()() 13 0.0000042
Chromium (total) o. ()()() 13 210 0.00042
Cobalt O. ()()() 12 210 0.000018
Copper 0.00015 660 0.00016
Cyanide 0.0000049 250 0.0000023
Iron 0.039 360,000 0.042
Lead 0.00015 290 0.0030
Magnesium 38,000 0.0019
Mercury 0.0000010 3.6 0.0000019
Nickel o. ()()() 13 250 O. ()()()()42
Silver 0.0000098
Tin O. {)()()() 14 250 0.000018
Vanadium 0.00014 620 0.000071
Zinc 0.35 1,300 0.00054
I Note: Blanks indicate chemical not of concern in the medium. .
I
DENlOO14F07.WPSI2
7-64
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Section 8.0
Description of Remedial Altneratives
-------
Section 8.0
Description of Remedial Alternatives
Feasibility Studies (PSs) were conducted to develop and evaluate remedial alternatives for
ground water, subsurface liquids, landfill solids and gas, soils, surface water, and
sediments at the Lowry Site. Several alternatives were assembled from the applicable
remedial technology process options and were screened for their effectiveness,
implementability and cost. The alternatives passing this screening were then evaluated in
further detail based on the nine criteria required by the NCP. This section provides a
description of each alternative that was retained for the detailed screening analyses in the
FSs. The alternatives consider no action and no further action, as required by the NCP,
to provide a point of comparison for other alternatives.
The descriptions of alternatives in this section follow the groupings of OU s by media:
shallow ground water and subsurface liquids (OU 1) and deep ground water (OU 6);
landfill solids (OU 2) and landfill gas (OU 3); and soils (OU 4), surface water, and
sediments (OU 5).
The descriptions of alternatives include the following components:
.
Treatment components
Treatment technologies that will be used;
Type and volume of waste to be treated;
Process sizing; and
Primary treatment levels.
.
Containment or storage components
Type of storage;
Type of closure that will be implemented;
Type and quantity of waste to be stored; and
Quantity of untreated waste and treatment residuals to be disposed
off site or managed onsite in a containment system and the degree of
hazard remaining in such waste.
.
General components and cost
Contaminated media addressed (and their physical location at the
Lowry Site);
Risk reduction (including initial risk);
Whether treatability testing has been or will be conducted;
Implementation requirements;
Institutional controls;
DENlOO153AA.WP5
8-1
-------
Residual levels;
Assumptions, limitations, uncertainties;
Estimated implementation time frame; and
Estimated capital, operation and maintenance (O&M), and present
worth costs.
.
Major ARARs, risk-based levels, and TBCs being met/utilized for the
specific components of the alternatives
How specific components of each alternative will comply with the
major ARARs and why the standard is applicable, or relevant and
appropriate.
In addition, for ground-water remedial alternatives, the following ground-water
components are addressed, as appropriate:
.
.
Ground-water classification;
Performance standards;
Estimated restoration timeframe; and
Area of attainment.
.
.
8.1 Cost Estimating Procedures
Alternatives were evaluated in terms of capital costs, annual or operation and
maintenance (O&M) costs, and present worth costs. Capital costs include the sum of the
direct capital costs (materials, equipment, labor, land purchases) and indirect capital costs
(engineering, licenses, or permits). Annual costs include the cost for labor, O&M,
materials, energy, equipment replacement, disposal, and sampling to operate the
treatment facilities. Present worth costs include capital costs and O&M costs calculated
over a 3O-year period.
The present worth analysis is used to evaluate expenditures that would occur over an
assumed 3D-year operation period by discounting all future costs to a common base year.
This allows the cost of remedial action alternatives to be compared on the basis of a
single figure representing the amount of money that, if invested in the base year and
disbursed as scheduled, would be sufficient to cover the costs associated with the
remedial alternative over its planned life.
Additional assumptions used in cost estimation include: a real discount rate of
five percent (the difference between the nominal discount rate and inflation is
five percent); and a constant value based on 1993 rates for materials expenses and
, ,
services.
DENlOO153AA.WP5
8-2
-------
The accuracy of costs is subject to substantial variation since details about the specific
design of each alternative (such as design details, the bidding climate, changes during
construction and operation, interest rates, labor and equipment rates, tax effects, and
other similar items) will not be lmown until the time of actual implementation of the
remedies.
Remedial Design efforts may also reveal that it is possible to reduce the original project
cost estimates. Reductions in the estimated costs could be the result of value engineering
conducted during Remedial Design. Through the value engineering process,
modifications could be made to the functional specifications of the remedy to optimize
performance and minimize costs. These changes would fall within the definition of "non-
significant modifications," as defmed by EP A's guidance for preparing Superfund
decision documents. For example, it may be determined that a reduction in costs could
be effected by non-significant changes to type, quantity, and/or cost of materials,
equipment, facilities, services, and supplies used to implement the remedy. It should be
noted that this type of design variance may have a noticeable impact on the estimated cost
of the remedy, but will not affect the remedy's ability to comply with the performance
standards.
8.1.1 Respondents' Cost Estimates
Standard cost data from the following sources were used in the OU RI/FSs prepared by
the various Respondents: EP A guidance, construction industry guidance, remedial action
contractors, vendors, and treatability studies. While the Respondents used these sources
to develop their cost data, each group of Respondents used varying approaches and
assumptions in developing the costs. As a result, the cost estimates were not directly
comparable across RI/FSs. EP A has revised the cost estimates as described below.
8.1.2 EPA's Revised Cost Estimates
Present worth cost calculations, as they appear in the ROD, differ slightly from those
presented in the feasibility studies for all OU s. In order to allow for the consistent
comparison of costs for the various alternatives, EP A recalculated the costs using a single
set of assumptions. The following factors were standardized for all alternatives: interest
rates and inflation rates.
8.2 Features Common to All Remedial Alternatives
All remedial alternatives, except for the No Action Alternative, have the following
common features:
.
Institutional Controls- Institutional controls are nonengineering methods
by which Federal, State, local governments, or private parties can prevent
or limit access to or use of a site. Institutional controls for the Lowry Site
DENIOOIS3AA.WPS
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.
DENlOOI53AA.WP5
shall include, but not be limited to, deed notices and restrictions that run
with the land; on site-access restrictions including, but not limited to,
fencing and warning signs; zoning controls; and well restrictions.
Executive Order No. 97, as issued by City and County of Denver Mayor
Federico Pefia, currently provides some measure of control. Institutional
controls at the Lowry Site must prohibit all activities and uses that EP A
determines would interfere or be incompatible with, or that would in any
way reduce or impair the effectiveness or protectiveness of, the sitewide
remedy. These shall include, but not be limited to, prohibitions on all
ground-water well construction and use not necessary for implementation
and monitoring of the selected remedy; prohibitions on access; and
prohibitions on activities and land use not connected with design,
construction, and implementation and monitoring of the selected sitewide
remedy. Offsite institutional controls shall serve as an additional measure
of protection to enhance the effectiveness of the selected remedy and to act
as preventative measures to preserve the implementability and effectiveness
of any of the selected remedy contingency measures. Offsite institutional
controls shall include, but not be limited to, deed notices and restrictions,
zoning controls, and well restrictions. These controls must prohibit all
offsite activities in the vicinity of the Lowry Site that would interfere or be
incompatible with, or that would in any way reduce or impair the
effectiveness or protectiveness of, the selected sitewide remedy.
All on site and offsite institutional controls shall be adequately administered,
maintained, and enforced.
The owner and operator of the Lowry Site shall be responsible for access
restrictions, warning signs, and fences.
Performance and Compliance Monitoring-To ensure that the
performance standards are met for all components of the selected remedy
for as long as contamination remains onsite, a long-term monitoring
program shall be designed and implemented during the RD/RA and shall
continue throughout the implementation of the selected sitewide remedy.
The monitoring program shall assess compliance with the remediation
levels in the ground-water system, monitor effluent chemical concentrations
from the treatment plant, evaluate the horizontal and vertical migration of
contamination, monitor the erosion of soils and sediments and monitor the
,
migration of landfill gases. Details of the monitoring program shall be
determined by EPA, in consultation with CDH, during the RD. The
monitoring program shall include, at a minimum, the following: analytical
p~e~rs and methods; indicator parameters; monitoring locations;
momtonng frequency and duration; sampling methods; well installation,
mainte~ance and aban~onment procedures; statistical methods for
evaluatIng data; reporting methods and procedures for tracking and
maintaining sample records; and QA methods, including data validation
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methods. The FSs estimated that approximately 60 to 100 ground-water
monitoring wells will be sampled semi-annually. Landfill gas shall be
monitored quarterly, or more frequently if migration is detected, using
approximately 40 to 60 monitoring wells. The ground-water monitoring
component of the selected sitewide remedy includes an early-warning
monitoring component; this will allow for a timely remedial response in the
event that EP A determines that additional remedial actions are necessary.
Soil and sediment erosion shall be monitored on a monthly basis using
three surface-water samplers installed in drainages. The actual details of
the monitoring program are subject to revisions and refinement during RD.
.
Five-Year Review-As specified in Section 121(c) of CERCLA, as
amended by SARA, and Section 300.430(t)(4)(ii) of the NCP, EPA will
review the sitewide remedy no less often than each 5 years after the
initiation of the remedial action to assure that human health and the
environment are being protected by the implemented remedy (this review
will ensure that the remedy is operating and functioning as designed and
that institutional controls are in place and are protective). An additional
purpose for the review is to evaluate whether the performance standards
specified in this ROD remain protective of human health and the
environment. EP A will continue the reviews until no hazardous
substances, pollutants, or contaminants remain at the Lowry Site above
levels that allow for unrestricted use and unlimited exposure.
8.3 Interim Remedial Measures
The following interim remedial measures, as described in Section 3.0 of this ROD, have
already been constructed and are operational at the Lowry Site. These measures shall
continue to operate in accordance with the existing design and operations criteria unless
EP A determines that modifications are needed:
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.
Ground-Water Barrier Wall-The ground-water barrier wall system shall
continue to be operated in accordance with the existing design and
operations program. The existing barrier wall consists of a 3Q-foot-deep,
I,OOO-foot-long compacted clay wall with a central collection sump. The
base of the barrier wall is anchored to the top of the unweathered bedrock
(Dawson formation).
.
Surface Water Removal Action (SWRA)-The Surface Water Removal
Action shall be continued and the collection system along unnamed creek
shall be maintained.
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.
Existing Ground-Water Treatment Plant (GWTP)-The existing ground-
water treatment plant shall be upgraded and maintained on the basis of
SWRA design criteria.
8.4 Description of Alternatives
8.4.1 Description of No Action Alternative
for all Operable Units
Evaluation of the No Action Alternative is required under CERCLA (as amended by
SARA) and is used as a baseline against which other alternatives are evaluated. Under
this alternative, no remedial action would be undertaken to treat, contain, or remove
contaminated media at the Lowry Site. All interim remedial measures currently being
taken at the Lowry Site would be discontinued. The SWRA collection system, existing
GWTP, and barrier wall would no longer function and would be allowed to deteriorate.
The landfill cap and existing fencing would be allowed to degrade and become
nonfunctional. Landfill gas and ground-water monitoring would also cease and no action
would be taken to prevent migration of contaminants offsite. No institutional or
operational controls would be implemented to restrict access to the Lowry Site or to
restrict exposure to contaminants.
There would be no reduction in the volume, toxicity, or mobility of the contaminants.
The overall volume of contaminated water could increase from infiltration. Monitoring
would not be a component of this alternative.
There would be no treatment or containment components associated with this alternative.
Under the No Action Alternative, all waste would be left in place and there would be no
reduction in risk. The remedial action objectives (RAOs) would not be met for this
alternative because contaminants would migrate offsite, and protection of human health
and the environment would not be achieved.
Because the interim remedial measures would be discontinued chemical- location- and
, , ,
action-specific would not be met.
The total 3O-year present worth cost of this alternative is $0 with no capital costs and no
annual O&M costs. The No Action Alternative would be immediately implementable.
8.4.2
OUs 1&6-ShaUow Ground Water
and Subsurface Liquids, and
Deep Ground Water
The following remedial alternatives were evaluated in detail during the FS for OUs 1&6:
.
Alternative GW-I-No Further Action'
,
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.
Alternative GW-2-North Boundary (Downgradient) Containment,
Collection, and Treatment;
.
Alternative GW-3-North Boundary and Toe of Landfill Containment,
Collection, and Treatment;
.
Alternative GW -4 - North Boundary, Toe of Landfill and Upgradient
Containment, Collection, and Treatment, Plus Multilayered Cap in Landfill
Area;
.
Alternative GW-5-North Boundary, Toe of Landfill and Lateral
Containment, Collection, and Treatment; and
.
Alternative GW-6-North Boundary and Toe of Landfill Containment.
In addition, EP A added the following alternative to the list of alternatives to be evaluated:
.
Modified Alternative GW-5 (North Boundary, Toe of Landfill and Lateral
Containment, Collection and Treatment, and Southern Containment,
Collection, and Diversion).
The alternatives for OUs 1&6 are described below. Major ARARs are identified for each
alternative. Additional ARARs for ODs 1&6 alternatives are presented in Table 8-1.
8.4.2.1 Alternative GW-1- No Further Action
The No Further Action Alternative (GW-I) would entail the continued implementation of
the existing interim remedial and monitoring measures at the Lowry Site. Under this
alternative, the following activities and components would be maintained:
DENlOO153AA.WP5
.
The existing ground-water barrier wall/collection system and treatment
facility would remain intact and functional. The existing ground-water
barrier system consists of a I,DOO-foot-long drain backed by a 30-foot-deep
compacted clay barrier.
.
The SWRA, which includes a collection system and an upgrade to the
treatment facility, would remain intact and functional.
.
The landfill cover would be maintained, and landfill gas monitoring would
continue.
.
Existing ground-water monitoring would continue.
.
Surface-water and ground-water restrictions that are currently in place
would continue.
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.
Existing on site and offsite institutional controls would be enforced.
Treatment components associated with this alternative include removal of contaminants in
ground water by air stripping and carbon adsorption. The existing treatment plant has an
optional aerobic biological treatment unit available if phenols and ketones are detected in
the early-warning monitoring well. Spent carbon is regenerated offsite and treated
ground water is injected into the shallow subsurface beyond the barrier wall. It is
estimated that 3.7 million gallons of ground water would be treated annually, resulting in
approximately 60 pounds per year of contaminants being removed. The SWRA
performance standards have been updated in this ROD to comply with current
requirements. Although the existing plant capacity is 30 gpm, the plant is currently
operating at about 15 gpm. The restoration time frame would be more than 30 years and
because wastes would be left in place, treatment would continue in perpetuity.
The barrier wall intercepts the northward migration of contaminants flowing through the
alluvium of unnamed creek as well as the seepage collected in the SWRA collection
system. The SWRA collection system keeps the waste-pit seepage separated from precip-
itation runoff, thus preventing contaminated water from migrating offsite during storm
events. The landfill cover minimizes production of leachate and limits migration into the
underlying Dawson Aquifer.
The remedy is primarily containment-based; therefore, wastes would be left in place.
The Baseline Risk Assessment for OUs 1&6 indicated that there are no current exposure
pathways to ground water. However, if onsite residents used ground water as a drinking
water source in the future, the estimated cancer risk would be lxl0"2. Onsite risks would
remain and would be controlled through the use of institutional controls. Estimated risk
for a residential setting using a hypothetical future offsite drinking water well in the
direction of regional ground-water flow could be 2xl0-5 within 30 years. This risk could
increase to lxl0"3 after 150 years of contaminant migration. Under the No Further
Action alternative, offsite migration of contaminants toward the north would be
prevented. It is assumed that contaminant migration toward the west, east, and south
would be controlled through monitoring and implementation of contingency measures.
However, the exact nature of these measures has not been identified or costed out. In the
absence of these contingency measures, contaminant migration toward the west, east, and
south would continue, and offsite risks would not be eliminated.
Treatability studies were performed during the ground-water treatment plant design, and
formed the basis for the original treatment train. Additional treatability studies were
conducted prior to the implementation of the SWRA. Based on these additional studies,
the treatment plant was upgraded to address a wider range of contaminants. Treatment
residuals from this alterative consist of spent carbon (4,000 pounds/month), which is
regenerated offsite approximately every 10 weeks. Other treatment residuals may include
solids from bag filters and, in the future, sludge from the biotreatment unit. The
alternative assumes that future treatment plant upgrades as described and mandated by the
SWRA would be adequate to treat all chemicals that may be present in the contaminated
ground water. The No Further Action Alternative would use current technologies.
DENlOO153AA.WPS
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The following major ARARs have been identified for this alternative:
DENlOOlS3AA.WPS
.
Colorado Water Quality Control Act (S CCR 1002-8), Colorado Basic
Standards for Ground Water, Classifications and Water Quality
Standards for Ground Water: These regulations establish standards for
both classified and unclassified ground water. The standards are applicable
because ground water (within confined, unconfined, and alluvial aquifers)
near the Lowry Site and ground water (within unconfined and alluvial
aquifers) within the Lowry Site have been classified for domestic- and
agricultural-quality use. Ground water within confined aquifers of the
Lowry Site is not classified. However, regulatory standards that are
pertinent to classified ground water also apply to unclassified ground water
for the protection of offsite beneficial uses of the ground water. Under this
alternative, ground water would be treated to meet these standards and then
discharged to the shallow ground-water system. This alternative would
comply with the requirements specified under these ARARs.
.
Safe Drinking Water Act, National Primary Drinking Water
Regulations (40 CFR Part 141) and the Colorado Primary Drinking
Water Regulations (S CCR 1003-1): These regulations establish health-
and treatment-based standards for public drinking water systems. These
regulations would be relevant and appropriate because the shallow and deep
ground water in the vicinity of the Lowry Site is being used or may be
used in the future as a source of water for a public water system or private
supply wells. Under this alternative, treated ground water from the
treatment plant would be injected into the shallow ground-water system.
This alternative would comply with the requirements specified under these
ARARs.
.
Safe Drinking Water Act, and National Secondary Drinking Water
Regulations (40 CFR Part 143): These regulations establish welfare-
based standards for public water supply systems and have been adopted by
the State of Colorado under the basic standards for ground water. The
regulations would be relevant and appropriate because the shallow and deep
ground water in the vicinity of the Lowry Site is being used or may be
used in the future as a source of water for a public water system or private
supply wells. Under this alternative, ground water would be treated to
meet these standards and then discharged to the shallow ground-water
system. This alternative would comply with the requirements identified
under these regulations.
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (S CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations are applicable because the treatment
plant is a source of air emissions. These regulations would be met for the
air stripper/carbon-polishing treatment process.
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This 3lternative includes contingency measures to ensure that RAOs and ARARs would
be met at the compliance boundary.
The total 3D-year present worth of this alternative is $31,970,000, with capital costs of
$4 300 000 and annual O&M costs of $1,800,000. The implementation time is
, , ,
immediate.
8.4.2.2 Alternative GW-2 - North Boundary (Downgradient)
Containment, Collection, and Treatment
Under Alternative GW-2, all existing interim remedial measures identified in the No
Further Action Alternative (GW-l) would continue. Additionally, a 2,2oo-foot ground-
water barrier wall and collection system (referred to as an extraction trench in the
Proposed Plan for OUs 1&6) would be constructed along the northern boundary of
Section 6. The barrier wall would be an extension of the existing barrier wall or a
separate barrier wall adjacent to the existing barrier wall. The effectiveness of the
existing barrier wall in capturing the northward migration of the contaminated ground
water would be evaluated to determine the necessary barrier wall configuration.
Contaminated ground water, collected from the new extraction trench and/or the existing
barrier wall, would be treated using the existing ground-water treatment plant.
The barrier wall would be constructed so that it would be anchored into the separation
layer, which in this area averages about 65 feet in depth. Four ground-water collection
sumps would be located along the collection system and connected to a header pipeline to
the existing ground-water treatment plant.
Since the barrier wall and collection system would capture additional ground water,
approximately 6.3 million gallons per year of contaminated ground water would be
treated, and would result in the removal of approximately 100 pounds per year of
contaminants. The restoration time frame would be more than 30 years, and since waste
would be left in place, treatment would continue in perpetuity.
This alternative is primarily containment-based; therefore, waste would remain in place.
Onsite risks would remain at unacceptable levels and would be controlled through
institutional controls. Offsite migration of contaminants toward the north would be
prevented. It is assumed that contaminant migration toward the west east and south
, ,
would be controlled through monitoring and implementation of contingency measures.
However, the exact nature of these measures has not been identified or costed out. In the
absence of these contingency measures, contaminant migration toward the west, east, and
south would continue, and offsite risks would not be eliminated.
Treatability testing has been performed in conjunction with the design of the existing
ground-water treatment plant and the SWRA. This alternative assumes that the existing
ground-water treatment plant would be adequate to treat all contaminants in ground-water
DENlOO153AA.WP5
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and waste-pit liquids. The alternative is considered implementable since proven
technologies are being proposed.
Major ARARs for this alternative are the same as the ARARs identified for the No
Further Action alternative (GW-l) and would be met by this alternative using similar
methods.
This alternative includes contingency measures to ensure that RAOs and ARARs would
be met at the compliance boundary.
The total 30-year present worth cost of this alternative is $39,010,000, with capital costs
of $9,800,000, and annual O&M costs of $1,900,000. The estimated implementation
time is 2 years.
8.4.2.3 Alternative GW-3 - North Boundary and Toe of
LandfiU Containment, CoUeetion, and Treatment
Under Alternative GW-3, all existing interim remedial measures identified in the No
Further Action Alternative (GW-l) would continue. The ground-water barrier wall and
collection system on the northern boundary of Section 6, as identified in
Alternative GW-2, would also be constructed. In addition, the other containment
components discussed for Alternative GW-2 would apply as well. For Alternative GW-3,
an additional ground-water extraction system, to extract highly contaminated ground
water, would be constructed near the toe of the landfill mass. This system would be
approximately 300 feet long and 50 feet deep, and would be constructed approximately
200 feet north of the downgradient edge of the landfill (termed "toe of the landfill").
The extraction system would consist of a subsurface drain, a line of extraction wells, or
horizontally drilled wells. For the comparative analysis of alternatives, it was assumed
that the ground-water extraction system would consist of 15 wells, 50 feet deep, and
20 feet apart. Ground water would be pumped to the surface and piped to the existing or
a new ground-water treatment facility for highly contaminated liquids.
The costs for a new ground-water treatment plant have been incorporated into this
alternative. The need for an additional ground-water treatment plant would be evaluated
during Remedial Design. A new ground-water treatment plant would need to be designed
and constructed unless it could be demonstrated through pilot-scale testing that the
existing ground-water plant could effectively treat the more highly contaminated ground
water to the performance standards.
The treatment technologies used for this alternative are part of the conceptual treatment
model presented in the FS for ODs 1&6 and include: gravity phase separation for
NAPLs; lime soda softening for metals, radionuclides, hardness, and solids; biological
treatment (pAcrn-) to remove organic compounds, BOD, COD, ammonia, and nitrate;
and granular-activated carbon to remove volatile organics in offgas streams.
DENIOOIS3AA.WP5
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The extraction system at the toe of the landfIll is expected to capture approximately
3.9 million gallons of contaminated ground water annually. The total annual amount of
ground water to be treated from the toe of the landfIll and the northern boundary would
be approximately 6.3 million gallons. Approximately 700 pounds per year of
contaminants would be removed and treated. Although the existing ground-water
treatment capacity is 30 gpm, the ground-water treatment plant is currently operating at
almost 15 gpm. If an additional ground-water treatment plant were required, it is
expected that it would be sized for 20 gpm. The restoration time frame would be more
than 30 years, and because waste would be left in place, treatment would continue in
perpetuity.
The remedy is containment based; therefore waste would be left in place. On site risks
would remain, and would be controlled through institutional controls. Offsite migration
of contaminants toward the north would be prevented. It is assumed that contaminant
migration toward the west, east, and south would be controlled through monitoring and
implementation of contingency measures. However, the exact nature of these measures
has not been identified or costed out. In the absence of these contingency measures,
contaminant migration toward the west, east, and south would continue, and off site risks
would not be eliminated.
The treatment technologies, tested during OUs 1&6 treatability study stages 1 through 3,
were selected on the basis of demonstrated effectiveness for removal. Residuals would
include spent vapor-phase granular activated carbon, solids from lime-soda softening, and
P AC'f"M solids. Carbon would be regenerated offsite and reused. Other solids (550 tons
of lime-softening and 430 tons of sludge produced annually from the biological treatment)
would be disposed in accordance with ARARs. The alternative would be implementable
since proven technologies are being proposed.
Major ARARs for this alternative are the same as the ARARs identified for the No
Further Action alternative (GW-I) and would be met by this alternative using similar
methods.
This alternative includes contingency measures to ensure that RAOs and ARARs would
be met at the compliance boundary.
The total 3O-year present worth cost of this alternative is $61,420,000 with capital costs
of $15,300,000, and annual O&M costs of $3,000,000. The estimated implementation
time is 3 years.
8.4.2.4
Alte17Ultive GW-4 - North Boundary, Toe of Landfill,
and Upgradient Containment, Collection and Treatment,
Plus Multilayered Cap in Landfill Area
Under Alternative GW-4, all provisions identified in Alternative GW-3 would be con-
structed, except the extraction system at the toe of the landfill would be 100 feet deep
DENlOO153AA.WPS
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rather than 50. All existing interim remedial measures identified in the No Further
Action alternative (GW-1) would continue. Containment components would include all
those described in Alternatives GW-2 and GW-3.
In addition, a 50-foot-deep containment, collection, and diversion system would be
constructed upgradient of (south of) the landfill mass. This ground-water extraction
system (3,600-foot-Iong) would be located upgradient of the source area, approximately
50 feet deep (keyed to the unweathered Dawson aquifer).
Also, a multilayer cap would be placed over the existing landfill cover and over the waste
pits in the fonner tire pile area. The multi-layered RCRA cap would cover 220 acres of
the Site, including the landfill and waste pits, and the northern pits near the fonner tire
pile area. Components of the cap would include a minimum of three feet compacted
native clay soil, flexible membrane cap (60-mil) constructed of high density polyethylene,
filler fabric to protect the drainage layer, and soil cover capable of supporting vegetation.
A RCRA Subtitle C landfill closure would be implemented.
Treatment components are the same as those described for Alternative GW-3.
Approximately 6.8 million gallons per year of contaminated ground water would be
treated, resulting in removal of approximately 700 pounds per year of contaminants. The
existing treatment capacity is 30 gpm. It is currently operating at almost 15 gpm. If an
additional treatment plant were required, it is expected that it would be sized at 20 gpm.
The upgradient system is expected to intercept 0.5 million gallons per year of clean
water, thereby reducing the volume of clean ground water mixed with contaminated
ground water. The restoration time frame would be 30+ years and because waste would
be left in place, treatment would continue in perpetuity.
The costs for a new treatment plant have been incorporated into this alternative. The
need for an additional treatment plant would be evaluated during Remedial Design. A
new treatment plant would need to be designed and constructed unless it could be
demonstrated through pilot-scale testing that the existing plant could effectively treat the
more highly contaminated ground water to the perfonnance standards.
This alternative is containment-based; therefore, waste would remain in place. Onsite
risks would remain, and would be controlled through institutional controls. Offsite
migration of contaminants toward the north and south would be prevented. It is assumed
that contaminant migration toward the west and east would be controlled through
monitoring and implementation of contingency measures. However, the exact nature of
these measures has not been identified or costed out. In the absence of these contingency
measures, contaminant migration toward the west and east would continue, and offsite
risks would not be eliminated.
The treatment technologies, tested during DUs 1&6 treatability study stages 1 through 3,
were selected on the basis of demonstrated effectiveness for removal. Residuals would
include spent vapor-phase granular activated carbon, solids from lime-soda softening, and
DENIOOI53AA.WPS
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PAC'J'"I solids. Spent carbon (approximately 4,000 pounds per mon~) would be
regenerated offsite. Other solids would be disposed in acc~rdance ,,:th ARARs. The
alternative would be implementable since proven technOlOgIes are bemg proposed.
Major ARARs for this alternative are the same as the ARARs identified in GW-1 and
would be met by this alternative using similar methods.
This alternative includes contingency measures to ensure that RAOs and ARARs would
be met at the compliance boundary.
The total 30-year present worth cost of this alternative is $113,300,000, with capital costs
of $64,100,000 and annual O&M costs of $3,200,000. The estimated implementation
time is 3 years.
8.4.2.5 Alternative GW-5 - North Boundary, Toe 01 Landfill,
and Lateral Containment, Collection and Treatment
Under Alternative GW-5, all existing interim remedial measures identified in the No
Further Action Alternative (GW-1) would continue. The ground-water collection system
would be constructed at the toe of the former landfill, as with Alternative GW-3.
Treatment components are also the same as those described for Alternative GW-3.
In addition, this alternative would provide for lateral containment of ground water on the
eastern and western boundaries of the Lowry Site through underground barrier walls and
collection systems. The lateral containment would consist of a barrier wall and collection
system measuring approximately 2,000 feet in length along the eastern boundary and
1,000 feet in length along the southwest portion of the compliance boundary.
Ground water would be intercepted annually in the amount of 6.3 million gallons.
Approximately 700 pounds of contaminants would be removed by the treatment system.
Although the existing treatment capacity is 30 gpm, it is currently operating at almost
15 gpm. If an additional treatment plant were required, it is expected that it would be
sized at 20 gpm. The restoration time frame would be 30+ years and because wastes
would be left in place, treatment would continue in perpetuity.
The costs for a new treatment plant have been incorporated into this alternative. The
need for an additional treatment plant would be evaluated during Remedial Design. A
new treatment plant would need to be designed and constructed unless it could be
demonstrated through pilot-scale testing that the existing plant could effectively treat the
more highly contaminated ground water to the performance standards.
The remedy is containment based; therefore, waste would be left in place. Onsite risks
would remain, and would be controlled through institutional controls. Offsite migration
of contaminants toward the north, west, and east would be prevented. It is assumed that
contaminant migration toward the south would be controlled through monitoring and
DENlOO153AA.WPS
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implementation of contingency measures. However, the exact nature of these measures
has not been identified or costed out. In the absence of these contingency measures,
contaminant migration toward the south would continue, and offsite risks would not be
eliminated.
Treatment technologies, tested during OUs 1&6 treatability study stages 1 through 3,
were selected on the basis of demonstrated effectiveness for removal. Treatment
residuals include spent vapor-phase granular activated carbon, solids from lime-soda
softening, and PAC'f"M solids. Spent carbon (approximately 4,000 pounds per month)
would be regenerated offsite. Other solids would be disposed in accordance with
ARARs. This alternative would be implementable because proven technologies are
proposed.
Major ARARs for this alternative are the same as the ARARs identified for GW-l and
would be met by this alternative using similar methods.
This alternative includes contingency measures to ensure that RAOs and ARARs would
be met at the compliance boundary.
The total 3O-year present worth cost of this alternative is $68,820,000, with capital costs
of $17,700,000 and annual O&M costs of $3,000,000. The estimated implementation
time is 3 years.
8.4.2.6
Alternative GW-6 - North Boundary and Toe of
Landfill Containment, Collection and Treatment,
and Waste-Pit Pumping
Under Alternative GW-6, all existing interim remedial measures identified in the No
Further Action Alternative (GW-l) would continue. Ground-water collection systems as
described in Alternative GW-3 would be constructed at the toe of the landfill mass. This
alternative includes the same containment components as identified for Alternatives GW-2
and GW-3. In addition, waste-pit pumping wells would be installed, liquids would be
extracted from waste pits, and the liquids would be treated.
Treatment components are the same as those described for Alternative GW-3. Treatment
technologies would include: gravity-phase separation for NAPLs; lime soda softening for
metals, radionuclides, hardness, and solids; biological treatment (pAC'f"M) to remove
organic compounds, BOD, COD, ammonia, and nitrate; and granular activated carbon to
remove volatile organics in offgas streams. Treatment residuals would be disposed in
accordance with ARARs.
Approximately 52 waste-pit extraction wells (one for each waste pit) would be installed
and pumped at 0.04 gpm per well, totaling about two gpm for all wells or 1.1 million
gallons per year. A total of 7.4 million gallons of ground water and waste-pit liquids
would be treated. Contaminant removal is estimated to total about 1,800 pounds per
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year. Although the existing treatment capacity is 30 gpm, .it is ~u,!ently operating. at
almost 15 gpm. If an additional treatment plant were requIred, 1t 1S expected that 1t
would be sized at 20 gpm. The restoration time frame would be 30+ years and because
wastes would be left in place, treatment would continue in perpetuity.
The costs for a new treatment plant have been incorporated into this alternative. The
need for an additional treatment plant would be evaluated during Remedial Design. A
new treatment plant would need to be designed and constructed unless it could be
demonstrated that the existing plant could effectively treat the more highly contaminated
ground water to the performance standards.
Although the remedy is primarily containment-based and waste would be left in place,
waste-pit extraction wells would remove approximately 1.1 million gallons per year.
On site risks would remain, and would be controlled through institutional controls.
Offsite migration of contaminants toward the north would be prevented. It is assumed
that contaminant migration toward the west, east, and south would be controlled through
monitoring and implementation of contingency measures. However, the exact nature of
these measures has not been identified or costed out. In the absence of these contingency
measures, contaminant migration toward the west, east, and south would continue, and
offsite risks would not be eliminated.
Treatment technologies, tested during ODs 1&6 treatability study stages 1 through 3,
were selected on the basis of demonstrated effectiveness for removal. Residuals from
gravity-phase separation, lime-soda softening, and biological treatment would be
thickened and dewatered. The dewatered solids are not expected to demonstrate RCRA-
toxicity characteristics and would therefore be disposed in a Subtitle D-equivalent landfill.
Spent granular activated carbon would be regenerated offsite. Residuals would include
spent vapor-phase granular activated carbon, solids from lime-soda softening, and
PAC-rnr solids. Spent carbon (approximately 4,000 pounds per month) would be
regenerated offsite. Other solids would be disposed in accordance with ARARs. This
alternative assumes sustained pumping from waste pits could be achieved. The imple-
mentability of this alternative could be affected by the technical feasibility of drilling and
installing extraction waste-pit well points.
Major ARARs for this alternative are the same as the ARARs identified for GW -1 and
would be met by this alternative using similar methods.
This alternative includes contingency measures to ensure that RAOs and ARARs would
be met at the compliance boundary.
The total 30-year present worth cost of this alternative is $72,570,000 with capital costs
~f $2?,3oo,000 and annual O&M costs of $3,400,000. The estimated implementation
time 1S 3 years.
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8.4.2.7
EPA's Prefe"ed Alternative - Modified Alternative GW-5 - North
Boundary, Toe of Landfill, and Lateral Containment,
Collection, and Treatment plus Upgradient
Containment, Collection, and/or Diversion
This alternative is similar to Alternative GW-5, but has been modified by the addition of
an upgradient containment/collection and/or diversion system. Modified
Alternative GW-5 would use barrier walls as the type of containment, collection, and
diversion system. Due to the presence of subsurface sand lenses at the Site, barrier walls
would be the most effective method to isolate site contaminants and restrict offsite
migration of contaminated ground water. This alternative would contain and treat onsite
shallow ground water. Modified Alternative GW-5 would include construction of
underground barrier walls and collection systems to the east, west, north, and south of
the Lowry Site and installation of a ground-water extraction system at the toe of the
landfill.
Collected liquids would be treated in the existing ground-water treatment facility, an
upgraded facility, or a new ground-water treatment facility, if required. Operation of the
existing ground-water barrier wall would continue. This alternative also includes
additional measures to address the potential for offsite migration of contaminated ground
water at the northern boundary. These measures include construction of a separate
barrier wall adjacent to the existing barrier wall, or construction of an extension to the
existing barrier wall.
Treatment components would be the same as those described for Alternative GW-3. The
following treatment technologies are part of the conceptual treatment model presented in
the FS for OUs 1&6: gravity phase separation for NAPLs; lime soda softening for
metals, radionuclides, hardness, and solids; biological treatment (pACT"') to remove
organic compounds, BOD, COD, ammonia, and nitrate; and granular activated carbon to
remove volatile organics in offgas streams. Treatment residuals would be disposed in
accordance with ARARs.
Approximately 6.3 million gallons of ground water would be intercepted on an annual
basis. Contaminant removal is estimated to total about 700 pounds per year. Although
the existing treatment capacity is 30 gpm, it is currently operating at almost 15 gpm. If
an additional treatment plant were required, it is expected that it would be sized at
20 gpm. The restoration time frame would be 30 + years and because waste would be
left in place, treatment would continue in perpetuity.
The costs for a new treatment plant have been incorporated into this alternative. The
need for an additional treatment plant would be evaluated during Remedial Design. A
new treatment plant would need to be designed and constructed unless it could be
demonstrated through pilot-scale testing that the existing plant could effectively treat the
more highly contaminated ground water to the performance standards.
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This alternative would effectively isolate onsite contaminated ground water from the
offsite ground-water systems through containment on the southern, eastern, western, and
northern boundaries. In addition, containment, collection, and treatment at the toe of the
landfill mass would extract highly contaminated liquids closer to the source.
While this alternative does include a limited treatment component, the remedy would be
primarily containment-based; therefore, waste would remain onsite. Because Modified
Alterl1ative-GW-5 would effectively restrict offsite migration of contaminated ground
water, this alternative would prevent offsite migration of contaminants and would
eliminate offsite risks. Onsite risks would remain, and would be controlled through
institutional controls.
Treatment technologies, tested during the OUs 1&6 treatability study stages 1 through 3,
were selected on the basis of demonstrated effectiveness for removal. Residuals would
include spent vapor-phase granular activated carbon, solids from lime-soda softening, and
P AC'f"K solids. Spent Carbon would be regenerated offsite and other solids would be
disposed in accordance with ARARs. This alternative would use current technology and
therefore would be implementable.
Major ARARs for this alternative are the same as the ARARs identified for GW -1 and
would be met by this alternative using similar methods.
RAOs relating to offsite migration would be met without the use of contingency
measures.
The total 3O-year present worth cost of this alternative is $65,030,000, with capital costs
of $19,000,000 and annual O&M costs of $2,400,000. The estimated implementation
time is 3 years.
8.4.3 OUs 2&3-Landfill Solids and Gas
The following alternatives were evaluated as part of the FS for OU s 2 and 3:
.
Landfill Solids (OU 2)
Alternative LFS-2 (No Further Action);
Alternative LFS-3 (Clay Cap);
Alternative LFS-4 (Drum Removal and Off site Disposal);
Alternative LFS-6 (Drum Removal/Low Temperature Thermal
Desorption/Stabilization/Disposal); and
Alternative LFS-7 (Landfill Mass Regrading).
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.
Landfill Gas (OU 3)
Alternative LFG-2 (No Further Action);
Alternative LFG-3 (Gas Collection/Enclosed Flare); and
Alternative LFG-5 (Gas Collection with Heat Recovery).
In addition, EP A added the following two alternatives to the list of alternatives to be
evaluated for consideration:
.
Modified Alternative LFS-4 (Drum RemovallOffsite Disposal/North Face
Cover); and
.
Modified Alternative LFG-3 (Gas Collection/Enclosed Flare).
These modified alternatives were discussed in the Proposed Plan for OUs 2&3, 4&5, and
the sitewide remedy.
Major ARARs for each alternative are identified below. Additional ARARs for OU s 2&3
alternatives are presented in Table 8-2.
8.4.3.1 Alternative LFS-2 - No Further Action
Under Alternative LFS-2, the No Further Action Alternative for landfill solids, no
additional remedial action would be undertaken to treat, contain, or remove contaminated
landfill solids within the landfill mass and the former tire pile area. Existing sitewide
operational measures pertinent to landfill solids such as cover maintenance, site access
restrictions and security, and interim remedial measures would continue to be operated
and maintained. Under these measures:
.
The landfill in Section 6 would remain closed and the existing landfill
cover would be maintained;
.
The existing soil cover in the former tire pile area would be maintained;
and
.
Existing institutional controls and onsite access restrictions including
fencing and warning signs, and land use restrictions including well drilling
restrictions would be enforced.
There are no treatment components associated with this alternative.
Containment of the landfill mass solids would be achieved by proper maintenance of the
existing cover on the landfill. Approximately 12 million cubic yards of landfill solids
would be contained.
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Because there are currently no residential or recreational uses at the Lowry Site, there is
no current risk from ingestion, inhalation, or skin adsorption of landfill solids. The
Baseline Risk Assessment indicated that if no remedial actions were taken, and if people
lived or worked (without protective regulations) on the Lowry Site, the excess cancer risk
could be I x 10-5 from ingestion or inhalation of contaminants.
There would be no reduction of toxicity, mobility or volume under the No Further Action
Alternative. By maintaining the existing landfill cover, risks from exposure to the solids
would be minimized.
The following major ARARs have been identified for this alternative:
Criteria for Classification of Solid Waste Disposal Facilities and
Practices (40 CFR Part 257): This requirement establishes criteria for
use in determining which solid waste disposal facilities and practices pose a
reasonable probability of adverse effects on health or the environment.
This requirement would be relevant and appropriate to maintenance of the
landfill cover and would be met through proper maintenance of the cap.
.
.
Regulations Concerning Municipal Solid Waste Landrills (40 CFR
Part 258): This requirement establishes the design and operational criteria
for solid waste landfills. The operational criteria would applicable to
closure and would be met through proper maintenance of the cap.
.
Colorado Solid Wastes Disposal Sites and Facilities Act (6 CCR
1007-2): This requirement establishes standards for municipal solid waste
disposal facilities. This requirement would be applicable to maintenance of
the landfill cap and would be met through proper maintenance of the cap.
The total 30-year present worth cost of this alternative is $7,260,000, with capital costs
of $36,000 and annual O&M costs of $470,000. The No Further Action
Alternative could be implemented immediately.
8.4.3.2 Alternative LFS-3 - Clay Cap
Under Alternative LFS-3, all existing interim measures identified in the No Further
Action Alternative would continue. In addition to the existing soil cover for the landfill
mass, a clay cap would be placed in the former tire pile area over areas where drums and
waste pits have been identified. This cap would provide an additional physical barrier
that would reduce the potential for contact with contaminated solids and reduce infiltra-
tion, thus reducing additional ground-water contamination. The drums at or near the
surface (approximately 10 drums) would be removed for offsite disposal at a Subtitle C
landfill. Additionally, approximately 600 tires from the unnamed creek area would be
removed and placed against the north toe of the landfill mass area. This alternative
would be simple to implement because it involves common earthwork.
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There would be no treatment components associated with this alternative.
The containment component of this alternative would be the placement of a 24-inch clay
cap in the former tire pile area (approximately 1.9 acres) where several metal anomalies
and drums have been identified. The area would be revegetated after the cap was placed.
Containment of the landfill mass solids would also be achieved by proper maintenance of
the existing cover on the landfill.
Although waste would be left in place (approximately 12 million cubic yards of solids),
risks would be reduced because the potential for exposure to the contaminated solids in
the landfill mass and the former tire pile area would be decreased due to the cap. No
treatability testing was conducted during the RIfFS that relates specifically to this
alternative.
Maintenance of the existing landfill mass cover would be performed in compliance with
RCRA Subtitle D regulations. The former tire pile area clay cap would meet pertinent
criteria for RCRA Subtitle D landfills. The drums at or near the surface would be
removed offsite for disposal. These drums would be transporte« and disposed of at a
RCRA Subtitle C facility which complies with the Superfund Offsite Policy.
The major ARARs for this alternative would be the same as those identified for Alterna-
tive LFS-2 and would be met by this alternative using similar methods.
The total 30-year present worth cost of this alternative is $6,970,000, with capital costs
of $670,000 and annual O&M costs of $410,000. The estimated time to implement
Alternative LFS-3 would be 1 year.
8.4.3.3 Alternative LFS-4 - Drum Removal/Offsite Disposal
Under Alternative LFS-4, all existing interim measures identified in the No Further
Action Alternative would continue. The alternative consists of continued maintenance of
the existing cover on the landfill mass; surface and subsurface drum removal from the
former tire pile area (approximately 1,350 drums); offsite treatment and disposal of
drums, drum contents, and contaminated soils from near the drums at an offsite RCRA
Subtitle C facility. The excavated areas would be backfilled and revegetated.
Liquids in drums (estimated at 1,300 gallons) removed would be transported to an offsite
RCRA Subtitle C facility for incineration and ash stabilization. Treatment by incineration
is expected to result in a 99.99 percent reduction in contaminants.
Containment of the landfill mass solids would be achieved by proper maintenance of the
existing cover on the landfill.
This alternative would result in the removal of approximately 1,350 drums and
contaminated material surrounding drums in the former tire pile area. All solids in the
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landfill mass (approximately 12 million cubic yards) would be left in place. Risks in the
former tire pile area from the unsaturated solids would be reduced by excavation and
offsite treatment and disposal of these materials. Risks posed by the landfill mass would
be reduced by decreasing the potential for exposure to the solids through maintenance of
the cover.
This remedy would be implementable because it utilizes conventional equipment,
construction techniques, and established treatment and disposal facilities. Institutional
controls such as access controls and land use restrictions would be required to limit
access to the Lowry Site.
Because solids in the landfill mass would not be treated or moved, residual levels would
be the same as the initial levels; solids in the former tire pile area would be excavated,
treated, and disposed to achieve the performance standards. This alternative assumes that
solids in the former tire pile area would only be excavated down to the depth of ground
water.
The major ARARs for this alternative would be the same as those for Alternative LFS-2
and would be met by this alternative using similar methods.
The total 3O-year present worth cost of this alternative is $8,700,000, with capital costs
of $2,400,000 and annual O&M costs of $410,000. The estimated time to implement
Alternative LFS-4 would be 6 months.
8.4.3.4 Alternative LFS-6 - Drum Removal/Low TemperaJure
Thermal Desorption/Stabilization/Disposal
Under Alternative LFS-6, all existing interim measures identified in the No Further
Action Alternative would continue. In addition, this alternative would consist of contin-
ued maintenance of the existing cover on the landfill mass area; surface and subsurface
drum removal from the former tire pile area (approximately 1,350 drums); offsite treat-
ment and disposal of the drums and drum contents; treatment of approximately
4,200 cubic yards of contaminated soil through desorption, stabilization, fixation and
onsite disposal, and reclamation of the former tire pile area.
Containment of the landfill mass solids would be achieved by proper maintenance of the
existing cover on the landfill.
All solid~ in the landfill mass (approximately 12 million cubic yards) would be left in
place. Risks posed by the landfill mass would be reduced by reducing the potential for
e~posure to the solids through maintenance of the cover. Risks posed by the former tire
pile area would be reduced by removing and treating the contaminated soil to the
performance standards.
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Results of treatability tests conducted during the RIfFS indicated that low temperature
thermal desorption would meet cleanup levels. This alternative would be implementable
because it would utilize conventional equipment and construction techniques, and
established treatment and disposal facilities. Institutional controls such as access
restrictions and land use restrictions would be required. This alternative might be
difficult to implement if soils were encountered with different contaminants than those
encountered for the treatability study. This alternative assumes that the soils used in the
treatability study would be sufficiently similar to those in the former tire pile area to
allow treatment levels to be met.
Because solids in the landfill mass would not be treated or moved, residual levels would
be the same as the initial levels; solids in the former tire pile area would be excavated
down to the depth of ground water to meet the performance standards.
Maintenance of the existing landfill mass cover would be performed in compliance with
RCRA Subtitle D regulations. Overpacked drums and bulk liquids would be transported
to an off site RCRA Subtitle C facility for incineration and ash stabilization.
Approximately 4,200 cubic yards of contaminated soil would be excavated and treated
through low temperature thermal desorption to separate volatile and semivolatile organic
compounds from soils. The treatment would be followed by stabilization of the soils to
minimize leaching of inorganic compounds from the soils. The stabilization would result
in an increase in volume to 6,000 cubic yards. The soils would be TCLP-tested and, if
they were not found to be RCRA characteristic wastes, would be disposed in an onsite
RCRA Subtitle D disposal cell.
Waste residuals produced by low temperature thermal desorption treatment technologies
would include condensate and treated soils. The condensate would be transported to an
offsite RCRA Subtitle C facility for incineration, and the treated soils would be stabilized
and disposed onsite. Vented gas produced through the operation of the low temperature
thermal system would meet standards outlined in the Clean Air Act, and the Colorado Air
Quality Act/Colorado Air Pollution Regulations.
The thermal desorption unit would be an existing unit on a trailer; retention time in the
treatment unit would be 1 to 5 hours.
The major ARARs identified for Alternative LFS-2 also apply to this alternative and.
would be met by this alternative using similar methods. In addition, the following major
ARARs have been identified:
.
Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities (40 CFR Part 264 and 6 CCR 1007-3
Part 264): This requirement establishes standards for the design and
operation of hazardous waste facilities and closure and post-closure care.
This requirement would be applicable if solids (including the soils) are
identified as a RCRA hazardous waste and relevant and appropriate if
solids are sufficiently similar to RCRA hazardous waste. In either event,
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.
the low temperature thermal desorption unit would be constructed and
operated to comply with these requirements.
Land Disposal Restrictions (40 CFR Part 268 and 6 CCR 1007-3
Part 268): This requirement establishes prohibitions on land disposal
unless treatment standards are met. If soils were determined to be a
hazardous waste, these restrictions would be applicable for disposal of the
soils following treatment. The soils would meet these requirements before
disposal.
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (5 CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations are applicable because the low
temperature thermal desorption system is a source of air emissions and
would be met for the low temperature thermal treatment process.
The total 3G-year present worth cost of this alternative is $11,500,000 with capital costs
of $5,200,000 and annual O&M costs of $410,000. The estimated time to implement
Alternative LFS-6 would be 1 year.
8.4.3.5 Alternative LFS-7-Landfill Mass Regrading
Under Alternative LFS-7, all existing interim measures identified in the No Further
Action Alternative would continue. In addition, under this alternative all existing waste-
pit liquid, gas, and ground-water monitoring wells would be abandoned. The soil cover
in the former tire pile area would be maintained. The top layers of the existing landfill
mass cover would be stripped and the clay stored temporarily. The landfill mass in
Section 6 would be regraded by placing approximately 1.2 million cubic yards of
additional municipal solid waste on top of the existing landfill and then the clay cover
would be placed. An additional 2-foot clay layer would be placed on the north face of
the landfill mass to minimize infiltration and erosion.
There are no treatment components associated with this alternative. Containment of the
landfill mass solids would be achieved by proper maintenance of the new cover on the
landfill. All waste would be left in place (approximately 12 million yards).
No treatability testing was conducted during the RIfFS that relates specifically to this
alternative. This alternative is implementable because it would utilize conventional
equipment and construction techniques, and established disposal facilities. Institutional
controls such as access restrictions and land use restrictions would be required.
Maintenance of the new landfill cover would continue.
The following major ARARs have been identified for this alternative:
DENlOO153AA.WPS
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.
Criteria for Classification of Solid Waste Disposal Facilities and
Practices (40 CFR Part 257) and Regulations Concerning Municipal
Solid Waste Landfills (40 CFR Part 258): These requirements establish
design and operational criteria for all new municipal solid waste landfills.
These requirements would be applicable to future landfIlling actions at the
Lowry Site. As proposed, this alternative would not meet these
requirements because it would not include the necessary liner and leachate
collection system.
.
Colorado Solid Wastes Disposal Sites and Facilities Act (6 CCR
1007-2): This requirement establishes standards for municipal solid waste
disposal facilities. This requirement would be applicable to future
landfilling actions at the Lowry Site. As proposed, this alternative would
not meet this requirement because the regulation requires that new
municipal solid waste disposal facilities be constructed with engineering
liners and leachate collection systems on a stable sub-base. This
alternative does not include these components.
The total 30-year present worth cost of this alternative is $5,380,000, with capital costs
of $0 and annual O&M costs of $350,000. The estimated time to implement
Alternative LFS-7 would be 9 months.
8.4.3.6 EPA's Prefe"ed Alternative-Modified Alternative LFS-4-
Drum Removal/Offsite Disposal/North Face Cover
Under Modified Alternative LFS-4, all existing interim measures identified in the No
Further Action Alternative would continue. Alternative LFS-4 was modified to increase
the volume of soils excavated, treated, and disposed offsite by including excavation of
contaminated materials associated with unsaturated waste pits in the former tire pile area.
Excavation would include waste-pit solids and surrounding contaminated soil and would
reduce contamination sources and thus, reduce adverse risks.
This alternative consists of continued maintenance of the existing soil cover on the
landfill mass; excavation of approximately 10 surface and 1,350 subsurface drums,
contaminated soils associated with the drums to a depth of 15 feet, and excavation of
approximately 15,000 cubic yards of contaminated materials associated with waste pits to
a depth of three feet beneath the bottom of each pit within the former tire pile area;
offsite treatment and disposal of drums, drum contents, and contaminated soils; and
reclamation of the former tire pile area.
This alternative also modifies Alternative LFS-4 to include an additional two feet of soil
cover on the north slope of the landfill mass. This additional cover would further reduce
risk from landfill solids by decreasing the potential for contact with contamination from
landfill solids and by minimizing infIltration and erosion.
DENlOOlS3AA.WPS
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Liquids in drums removed (estimated at 1,300 gallons) would be transported to an off site
RCRA Subtitle C facility for incineration and ash stabilization. Treatment would be
expected to result in a 99.99 percent reduction of contaminants.
Containment of the landfill mass solids would be achieved by proper maintenance of the
existing cover on the landfill. Landfill solids in the landfill mass would remain in place.
Approximately 15,000 cubic yards of contaminated material would be removed from the
former tire pile area.
Risks would be reduced because of the diminished potential for exposure to contaminated
solids. Risks in the former tire pile area from the unsaturated solids would be eliminated
by excavation of these materials.
This alternative is implementable because it would utilize conventional equipment and
construction techniques, and established treatment and disposal facilities. Institutional
controls such as access restrictions and land use restrictions would be required.
Because solids in the landfill mass would not be treated or moved, residual levels would
be the same as the initial levels; solids in the former tire pile area would be excavated to
the performance standards and treated and disposed offsite.
The major ARARs identified for this alternative are the same as those identified for
Alternative LFS-2 and would be met by this alternative using similar methods.
The total 3O-year present worth cost of this alternative is $13,460,000 with capital costs
of $8,600,000 and annual O&M costs of $316,000. The estimated time to implement
Modified Alternative LFS-4 Alternative would be 1 year.
8.4.3.7 AlternaJive LFG-2 - No Further Action
Under LFG-2, the No Further Action Alternative for landfill gas, no additional remedial
action would be undertaken to treat, contain, or remove landfill gas. The perimeter gas
monitoring program at existing gas probes would be continued. Existing sitewide opera-
tional measures such as cover maintenance, site access restrictions and security, and
interim remedial measures would continue to be maintained.
There are no treatment or containment components associated with this alternative.
There would be no reduction of toxicity, mobility, or volume. This alternative would not
be protective of human health and the environment because it would not prevent gas
migration from occurring.
The Baseline Risk Assessment indicated that if people lived on the Lowry Site, there
would be a probability that 100% of the population would contract cancer from exposure
to vinyl chloride and other contaminants in landfill gas. In addition, there would be risks
DENlOOIS3AA.WPS
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of injury due to explosion and adverse health effects to individuals exposed to landfill gas
on or offsite.
The following major ARARs have been identified for this alternative:
.
Criteria for Classification of Solid Waste Disposal Facilities and
Practices (40 CFR Part 257) and Regulations Concerning Municipal
Solid Waste Landf"ills (40 CFR Part 258): These requirements establish
design and operational criteria for all new municipal solid waste landfills.
These requirements are relevant and appropriate because the Lowry Site
operated as a landfill and accepted municipal solid waste. These
requirements might not be met because landfill gas might migrate offsite
above the regulated limits in the future.
.
Colorado Solid Wastes Disposal Sites and Facilities Act (6 CCR
1007-2): This requirement establishes standards for municipal solid waste
disposal facilities. This requirement would be applicable to the closed
landfill at the Lowry Site. The requirement might not be met because
landfill gas might migrate offsite above the regulated limits in the future.
The total 30-year present worth cost of this alternative is $943,000, with capital costs of
$36,000 and annual O&M costs of $59,000. The No Further Action Alternative could be
implemented immediately.
8.4.3.8 Alternative LFG-3 - Gas Collection/Enclosed Flare
Alternative LFG-3 for Landfill Gas involves the placement of gas collection wells in the
interior and at the perimeter of the former landfill area and treatment of the gas by an
enclosed flare. It also incorporates all elements of Alternative LFG-2. The main objec-
tive of this gas collection system is to prevent lateral migration of gas offsite. This
alternative would be implemented in stages. The staged approach would be to add gas
collection wells, as necessary, to control gas migration.
.
Stage 1 would involve constructing approximately seven perimeter
collection wells and two interior collection wells.
.
Stage 2 would be implemented if gas monitoring indicates that gas is
migrating beyond the perimeter of the landfill mass. Stage 2 would add
approximately 14 perimeter collection wells.
.
Stage 3 would add approximately 26 gas extraction wells in the interior if
Stages 1 and 2 did not prevent gas migration at the perimeter.
To supplement the existing gas monitoring network, additional gas monitoring probes
would be installed along the perimeter of the Lowry Site to improve the gas monitoring
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system (approximately 26 probes would be added to the existing 17 probes). The gas
monitoring probes would be analyzed for methane and VOCs. The levels of methane and
VOCs would be compared to performance standards to determine if the extraction system
was effective in preventing offsite gas migration and if Stages 2 and 3 were necessary.
All existing gas, waste-pit liquid, and ground-water monitoring wells within the landfill
mass would be abandoned to eliminate the potential for vertical gas migration from the
wells.
The collected gas would be treated at approximately 750 standard cubic feet per minute
(sefm) per day using an enclosed flare with an 8-foot-diarneter stack approximately
40 feet high. It is estimated that treatment would result in approximately 98 percent
destruction of VOCs. Condensate collected in the gas collection system would be treated
in the existing ground-water treatment system.
Approximately 15 tons per year of VOCs would be treated using Stage 1 only and
approximately 40 tons per year of VOCs would be treated using Stage 2. Treatability
testing was conducted as part of the FS. This alternative would be implementable
because the system would use established and reliable technologies. Institutional controls
such as access restrictions and land use restrictions would be required. Residuallevels
would achieve performance standards because extraction would continue until the
standards were met. This alternative assumes that methane would continue to be
generated in quantities sufficient to operate the flare.
The potential for adverse offsite risk (health and explosion) would be significantly
reduced through the collection and treatment of gas.
The following major ARARs have been identified for this alternative:
DENIOOIS3AA.WPS
.
Clean Air Act [including NAAQS (40 CFR Part 50), NESHAPS (40
CFR Part 61), and NSPS (40 CFR Part 60)): These requirements
establish emissions standards for air pollutants. NAAQS would be
applicable, and NESHAPS and NSPS would be relevant and appropriate
because gas would be flared under this alternative. These requirements
would be met at the compliance boundary.
.
Colorado Air Quality Control Act/Colorado Air Pollution Regulations
(5 CCR 1001): These regulations establish standards for air emissions
from stationary sources. These regulations would be applicable during
construction and operations activities, and would be met by this alternative.
.
Regulations Concerning Municipal Solid Waste Landf"ills (40 CFR
Part 258): This requirement establishes design and operational criteria for
all new municipal solid waste landfills. This requirement would be
relevant and appropriate because the Lowry Site operated as a landfill and
accepted municipal solid waste. The regulations include controls for
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explosive gas. The requirement would be met because landfIll gas would
be prevented from migrating offsite.
Proposed Standards of Performance for New Stationary Sources and
Guidelines for Control of Existing Sources-Municipal Solid Waste
Landfills (40 CFR Part 60, Subpart WWW): This requirement
establishes performance standards for new stationary sources. This
requirement would be a to-be-considered (TBC) regulation because the
standards are proposed. Landfill gas would be collected and flared, and
would meet these proposed standards.
The total 3O-year present worth cost of Stage 1 of Alternative LFG-3 is $7,970,000, with
capital costs of $3,200,000 and annual O&M costs of $310,000. The estimated time to
implement Stage 1 of the LFG-3 Alternative would be 6 months.
.
The total 3O-year present worth cost of Stage 2 Alternative of LFG-3 is $8,830,000, with
capital costs of $3,600,000 and annual O&M costs of $335,000. These costs include the
costs for implementation of Stage 1. The estimated time to implement Stage 2 of the
LFG-3 Alternative would be 6 months.
The total 3O-year present worth cost of Stage 3 Alternative of LFG-3 is $12,930,000 with
capital costs of $5,200,000 and annual O&M costs of $503,000. These costs include the
costs for implementation of Stages 1 and 2. The estimated time to implement Stage 3 of
the LFG-3 Alternative would be 6 months.
8.4.3.9 Alternative LFG-5 -Gas Collection with Heal Recovery
Alternative LFG-5, for Landfill Gas, includes all of the components of Alterna-
tive LFG-3. This alternative would add a heat recovery system which would utilize heat
from the enclosed flare for onsite use. At this time, a practical and economical use for
this heat, such as heating offices or maintenance facilities, has not been identified.
Approximately 15 tons per year of VOCs would be treated using Stage 1 only and
approximately 40 tons per year of VOCs would be treated using Stage 2.
The major ARARs identified for this alternative are the same as those identified for
Alternative LFG-3 and would be met by this alternative using similar methods.
The total 30-year present worth cost of Stage 1 of Alternative LFG-5 is $8,510,000, with
capital costs of $3,700,000 and annual O&M costs of $313,000. The estimated time to
implement Stage 1 of the LFG-5 Alternative would be 6 months.
The total 3O-year present worth cost of Stage 2 of Alternative LFG-5 is $9,330,000, with
capital costs of $4,100,000 and annual O&M costs of $340,000. These costs include the
costs for implementation of Stage 1. The estimated time to implement Stage 2 of the
LFG-5 Alternative would be 6 months.
DENlOO153AA.WPS
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The total 3D-year present worth cost of Stage 3 of Alternative LFG-5 is $13,510,000,
with capital costs of $5,700,000 and annual O&M costs of $508.,000. ~ese c~sts
include the costs for implementation of Stages I and 2. The estimated time to Implement
Stage 3 of the LFG-5 Alternative would be 6 months.
8.4.3.10 EPA's Prefe"ed Alternative-Modified Alternative LFG-3-
Gas Collection/Enclosed Flare
EPA's preferred alternative, Modified Alternative LFG-3 for Landfill Gas, includes
Stages I and 2 of Alternative LFG-3, to be implemented simultaneously. By combining
these stages, the potential for gas migration would be decreased, minimizing exposure
and thus reducing risks.
Rather than immediately removing existing wells as in Alternative LFG-3, EPA would
evaluate existing gas, waste-pit liquid, and ground-water monitoring wells within the
landfill for future use. Wells that are no longer effective would be abandoned.
Approximately 21 perimeter collection wells and two interior collection wells would be
installed to intercept migrating gas, and the gas would be treated with an enclosed flare.
Approximately 26 additional gas monitoring wells would be installed along the perimeter
of the Lowry Site to improve the perimeter gas monitoring system (17 gas monitoring
wells currently exist onsite). If EPA determines that the combined Stages I and 2 efforts
are unsuccessful in preventing migration or meeting performance standards, Stage 3
would be activated and would involve installation of approximately 26 interior collection
wells.
Approximately 40 tons per year of VOCs would be treated using Stage 2. The gas would
be treated at a rate of approximately 2,000 scfm per day using an enclosed flare with an
8-foot-diameter stack approximately 40 feet in height. Condensate collected in the gas
collection system would be treated in the existing ground-water treatment system. It is
estimated that treatment would achieve approximately 98 percent destruction of VOCs.
There would be no containment components associated with this alternative.
Treatability testing was performed during the FS and showed that cleanup levels can be
met. This alternative would be implementable because the systems would use established
and reliable technologies. Institutional controls including access restrictions and land use
restrictions would be required. Residual levels would achieve performance standards
because extraction would continue until the standards were met. This alternative assumes
that methane would continue to be generated in quantities sufficient to operate the flare.
The major ARARs identified for this alternative are the same as those identified for
Alternative LFG-3 and would be met by this alternative using similar methods.
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The total 3O-year present worth cost of EPA's preferred alternative, Modified
Alternative LFG-3, is $8,430,000 with capital costs of $3,200,000 and annual O&M
costs of $340,000. The estimated time to implement Modified Alternative LFG-3 would
be 6 months. If Stage 3 were required, it is estimated that capital costs would increase
by $1,575,000. O&M costs would require an additional $168,000 per year and the total
present worth would increase by $4,160,000.
8.4.4 OUs 4&5-Soils, Surface Water, and Sediments
The following alternatives were evaluated in detail during the FS for OUs 4&5, and were
described in the Proposed Plan for OUs 2&3 and 4&5, issued in August 1993:
.
Soils (OU 4)
Alternative SOIL-I, No Further Action;
Alternative SOIL-2, Access Restrictions and Dust Controls;
Alternative SOIL-4a, Option 1, Excavation (as needed) and Landfill
(onsite);
Alternative SOIL-4a, Option 2, Excavation (one time) and Landfill
(onsite);
Alternative SOIL-4b Option 1, Excavation (as needed) and Landfill
(offsite); and
Alternative SOIL-4b Option 2, Excavation (one time) and Landfill
(offsite).
.
Surface Water (OU 5)
No Further Action.
.
Section 6 Sediments (OU 5)
Alternative SED6-1, No Further Action; and
Alternative SED6-2, Access Restrictions.
.
Section 31 Sediments (OU 5)
Alternative SED31-1, No Further Action;
Alternative SED31-2, Access Restrictions and Capping; and
Alternative SED31-3, Excavation and Landfill.
These alternatives are described in the following paragraphs. Major ARARs are
identified for each alternative. Additional ARARs for OU s 4&5 alternatives are
presented in Table 8-3.
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8.4.4.1 EPA's Preferred Alternative-Alternative SOIL-I-No Further
Action
Under Alternative SOIL-1, the No Further Action Alternative for soil, no additional
remedial action would be undertaken to treat, contain, or remove contaminated soil.
Contaminated soil consists of approximately 2.5 million cubic yards contaminated with
low levels of arsenic, beryllium, polychlorinated biphenyls, and dioxins/furans.
This alternative would include maintenance of the SWRA, including the barrier wall, and
existing institutional controls; perfonnance and compliance monitoring associated with the
collection system and treatment facility; and continued operation of the SWRA. The
landfill in Section 6 would remain closed and the existing landfill mass cover would be
maintained. The existing soil cover in the fonner tire pile area would be maintained.
Existing Lowry Site access and land use restrictions would continue; fencing and
vegetative cover would be maintained. Visual. monitoring of the soil areas would be
carried out to identify areas of erosion. Periodic monitoring of the surface water runoff
would be conducted to determine if any contamination is migrating offsite. One
automated surface water runoff sampler would be installed in the Section 31 drainage to
monitor the runoff.
There would be no treatment components associated with this alternative. There would
be a continuation of existing institutional controls including site fencing, signage, access
and land use restrictions.
All of the soil (approximately 2.5 million cubic yards) would be left untreated on site.
Contaminated soil spans approximately 103 acres in the northern half of Section 6. The
area is divided into two portions, one east of the unnamed creek and the other west of the
unnamed creek. Because the soil would not be treated or removed under this alternative,
the residual contaminant levels would be the same as the initial levels.
The Baseline Risk Assessment calculated a combined maximum excess cancer risk of
3 x 10-5 for a future resident adult and a future resident child from the ingestion and
inhalation of soil contaminated with arsenic, beryllium, polychlorinated biphenyls, and
dioxins/furans within the sewage sludge application/leachate injection area (Group 1).
The Baseline Risk Assessment estimated that the cancer risks posed to human health and
the environment by soil at the Lowry Site were within EP A's acceptable risk range. A
noncancer III greater than 1 was estimated for a future resident child that ingests and
inhales soil from the sewage sludge application/leachate injection area (Group 1) or the
sewage sludge application area (Group 2). Although there would be no reduction in
toxicity, mobility or volume through treatment, the No Further Action Alternative would
be protective of human health and the environment because estimated cancer risk is
wi~ ~e acceptable range and noncancer risk would be controlled by land use
restrictions.
DENlOO153AA.WPS
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No treatability testing was performed during the RIfFS for soil because the alternatives
considered are proven technologies. This alternative would be fully implementable. The
automated surface water sampler would be installed within the first year.
The following major ARARs have been identified for this alternative:
.
Colorado Air Quality Control Act/Colorado Air Pollution Regulations
(S CCR 1001): These regulations establish standards for air emissions
from stationary sources. These regulations would be applicable during
maintenance activities for the vegetated soil cover and would be met by
this alternative.
The RAOs would be achieved for this alternative through institutional controls which
would reduce the disturbance of and exposure to the soil.
The total 3O-year present worth cost of this alternative is $390,000 with capital costs of
$22,000 and annual O&M costs of $24,000. The estimated time to implement the No
Further Action alternative would be less than 1 year.
8.4.4.2 Alternative SOIL-2 - Access Restrictions and Dust Control
Alternative SOIL-2 would include installation of 13,200 linear feet of 6-foot-high chain
link fence topped with three strands of barbed wire to restrict access to the Site.
In addition, the elements of Alternative SOIL-I, the No Further Action alternative would
be included.
As a dust control and prevention measure, approximately 103 acres of the soil would be
regraded, covered with six inches of topsoil, and vegetated with seed and mulch as a dust
control and erosion prevention measure. Additionally, during revegetation and fence
installation activities, water spraying would be used to minimize generation of fugitive
dust. Existing site access and land use restrictions regarding use of the site surface,
surface water, and ground water would be continued.
Visual monitoring of the soil and vegetative cover would be performed on a monthly
basis. Annual monitoring of the surface water runoff would be carried out to evaluate
potential for contaminant migration. One automated surface water runoff sampler would
be installed in the Section 31 drainage to monitor the runoff.
There would be no treatment components associated with this alternative.
This alternative would contain the soil via placement of the topsoil and vegetative cover.
The potential for chemical migration through air-borne particulates and runoff erosion
would be reduced because of the topsoil and vegetative cover over the soil. All of the
soil (approximately 2.5 million cubic yards) would be left untreated onsite; but since the
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soil would be covered, the risks from inhalation and ingestion of soil would be
eliminated. .
The Baseline Risk Assessment estimated that the cancer risks posed to human health and
the environment by soil at the Lowry Site were within EPA's acceptable risk range. The
noncancer HI greater than 1 was estimated for a future resident child that ingests and
inhales onsite soil. Under this alternative since the soil would be covered, the risks from
inhalation and ingestion of soil would be eliminated.
Because the soil would not be treated under this alternative, the residual contaminant
levels would be the same as the initial levels. However, exposure pathways would be
incomplete and risk would not be present.
No treatability testing was performed for soil, because the alternatives considered are
proven technologies. This alternative would be implementable because it uses proven
methods of remediation. The automated surface water sampler would be installed within
the first year.
The following major ARARs have been identified for this alternative:
.
Colorado Air Quality Control Act/Colorado Air Pollution Regulations
(5 CCR 1001): These regulations establish standards for air emissions
from stationary sources. These regulations would be applicable during
construction and operations activities and would be met by this alternative.
Although fence installation, soil grading and vegetation activities might increase the
potential for short-term exposure and habitat disturbance, the RAOs would be achieved
for this alternative through a reduced potential for long-term exposure to the soil.
Toxicity, mobility, and volume of the contaminants would not be reduced by this
alternative.
The total 30-year present worth cost of this alternative is $2,080,000 with capital costs of
$1,400,000 and annual O&M costs of $44,000. The estimated time to implement
Alternative SOIL-2 would be 1 year.
8.4.4.3 Alternative SOIL-4a Excavation and Landfill (onsite)
Alternative SOIL-4a for soil would include excavation of approximately 2.5 million cubic
yards of contaminated soil to a depth of 15 feet. The excavated soils would then be used
as a daily cover in the on site landfilling operations. In addition, the elements of the
Alternative SOIL-I, No-Further Action, would be included.
Contaminated soil consists of approximately 2.5 million cubic yards contaminated with
low levels of arsenic, beryllium, polychlorinated biphenyls, and dioxins/furans. The soil
DENIOOIS3AA.WPS
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spans approximately 103 acres in the northern half of Section 6. The area is divided into
two portions, one east of the unnamed creek and the other west of the unnamed creek.
There are two options for excavation:
.
Option I-Excavate soil on an as needed basis for daily landfill cover; or
.
Option 2 - Excavate soil at one time and stockpile material for use as daily
cover in landfill.
RCRA Subtitle D landfill cells would be constructed on Section 6 in which the excavated
soil would be used as the daily cover. The new landfill would receive municipal solid
waste. Excavation of the soil would be to a depth of 15 feet. The areal extent of the
excavation would be 103 acres. Dust suppression techniques would be used to minimize
fugitive dust.
Land use restrictions that are currently in place regarding use of the site surface, surface
water, and ground water would be continued.
Annual monitoring of the surface water runoff would be carried out to evaluate potential
for contaminant migration. One automated surface water runoff sampler would be
installed in the Section 31 drainage to monitor the runoff. Installation of the sampler
would be achieved within the first year.
Construction of additional landfill cells would be in compliance with the RCRA
Subtitle D requirements. Landfill design would promote surface drainage, minimize
erosion of the cover and reduce the potential for precipitation permeation and leachate
generation. Disposal of soil, in the form of daily cover over the municipal solid waste,
would result in the containment of the contaminants in the soil within the landfill.
There are no treatment components associated with this alternative.
All of the soil (approximately 2.5 million cubic yards) would be left untreated onsite.
Because the soil would not be treated or moved off site under this alternative, the residual
contaminant levels would be the same as the initial levels. However, because the soils
would be used as daily cover, exposure pathways would be incomplete.
The Baseline Risk Assessment estimated that the cancer risks posed to human health and
the environment by soil at the Lowry Site were found to be already within EPA's
acceptable risk range. Under this alternative, the long-term risk from the ingestion and
inhalation of soil would be eliminated because of the containment of the soil; however,
there would be an increased potential for short-term risk from dust generation during
excavation, stockpiling, and handling of the soil.
No treatability testing was carried out for soil, because the alternatives considered are
proven technologies. Construction of the additional landfill cells and complete utilization
DENlOO153AA.WPS
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of the excavated soil would be expected to take 10 years. In Option 2, onsite stockpiling
would be .difficult to implement because of limited area available in Section 6, as well as
the potential interference with the daily landfilling activities.
Existing institutional controls would continue under this alternative.
The following major ARARs have been identified for this alternative:
.
Regulations Concerning Municipal Solid Waste Landiills (40 CFR
Part 258): This requirement establishes design and operational criteria for
all new municipal solid waste landfills and would be applicable because
new landfill cells would be constructed. This standard would be met
through proper design and operation of the landfill cells.
.
Regulations Pertaining to Solid Waste Disposal Sites and Facilities
(6 CCR 1007-2, Section 1): This requirement establishes standards for
new solid waste disposal facilities. Standards for design, construction and
operation of landfill cells would be applicable because new landfill cells
would be constructed and soils would be landfilled. These standards would
be met through proper design of the landfill cells.
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (5 CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations would be applicable during
construction and operations activities, and would be met by this alternative.
Although soil excavation, stockpiling and movement activities would increase the
potential for short-term exposure and habitat disturbance, the RAOs would be achieved
for this alternative through a reduced potential for long-term exposure to the soil.
Neither toxicity nor volume of the contaminants would be reduced by this alternative.
Mobility would be significantly reduced because of the use of the soil as a daily cover in
a RCRA Subtitle D landfill.
The total 30-year present worth cost for Option I of this alternative is $490,000 with
capital costs of $43,000 and annual O&M costs of $29,000. The estimated time to
implement Option 1 of Alternative SOIL-4a would be 10 years, at which point all
contaminated soil would have been used as daily cover.
Th~ total 30-year present worth cost for Option 2 of this alternative is $3,280,000 with
capital costs of $2,800,000 and annual O&M costs of $31,000. The estimated time to
implement Option 2 of Alternative SOIL-4a would be 10 years, at which point all
stockpiled soil would have been used as daily cover.
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8.4.4.4 Alternative SOIL-4b, Excavation and Landfill (offsite)
Alternative SOIL-4b for soil includes excavation of approximately 2.5 million cubic yards
of contaminated soil to a depth of 15 feet. In addition, all elements of Alterna-
tive SOIL-I, No-Further Action would be included in this alternative. The contaminated
soil spans approximately 103 acres in the northern half of Section 6. The area is divided
into two portions, one east of the unnamed creek and the other west of the unnamed
creek. Under this alternative, excavated soil would be transported to the Section 31
RCRA Subtitle D landfill to be used as daily cover.
There are two options for excavation:
.
Option I-Excavate soil for daily landfill cover on an as needed basis; or
.
Option 2 - Excavate soil at one time and stockpile material for use in the
landfill.
The areal extent of the excavation would be 103 acres. Dust suppression techniques
would be used to minimize fugitive dust. Under Option 2, the soil stockpile would be
vegetated to minimize contaminant migration, since the soil might be stockpiled up to
10 years.
Land use restrictions that are currently in place regarding use of the site surface, surface
water, and ground water would be continued. Annual monitoring of the surface water
runoff would be carried out to evaluate potential for contaminant migration. One
automated surface water runoff sampler would be installed in the Section 31 drainage to
monitor the runoff.
There would be no treatment components associated with this alternative.
Under Option 1, the soil would be used as a daily cover in the offsite landfilling opera-
tions in Section 31, on an as needed basis. Under Option 2, excavated soil would require
intermediate stockpiling for the one-time excavation of all soil and would later be used as
daily cover in the offsite landfilling operations in Section 31. Dust control measures
would be applied to the stockpile in the latter case.
All of the soil (approximately 2.5 million cubic yards) would be removed from the Lowry
Site and transported to Section 31 for use as daily cover. The existing contamination
would be eliminated because the soil would be excavated and moved offsite.
The Baseline Risk Assessment estimated that the cancer risks posed to human health and
the environment by soil at the Lowry Site were found to be already within EP A's
acceptable risk range. Under this alternative, the long-term risk from ingestion and
inhalation of soil would be eliminated; however, there would be a potential for short-term
risk from dust generation during excavation, stockpiling and additional handling of the
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soil. No treatability testing was carried out for soil, because the alternatives considered
are proven technologies.
Construction of the additional landfill cells as well as complete utilization of the
excavated soil would be expected to take 10 years. Installation of the automated surface
water sampler would be achieved within the first year. Existing institutional controls
would continue under this alternative.
The following major ARARs have been identified for this alternative:
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (S CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations would be applicable during
construction and operations activities, and would be met by this alternative.
Although soil excavation and transport to Section 31 would increase the potential for
short-term exposure and habitat disturbance, the RAOs would be achieved for this
alternative through a reduced potential for long-term exposure to the soil.
The total 30-year present worth cost for Option 1 of this alternative is $1,880,000 with
capital costs of $1,200,000 and annual O&M costs of $44,000. The estimated time to
implement Option 1 of Alternative SOIL-4b would be 10 years, at which point all
contaminated soil would have been used as daily cover.
The total 30-year present worth cost for Option 2 of this alternative is $4,800,000 with
capital costs of $4,000,000 and annual O&M costs of $52,000. The estimated time to
implement Option 2 of Alternative SOIL-4b would be 10 years, at which point all
excavated soil would have been used as daily cover.
8.4.4.5 EPA's Prefe"ed Altemative- Alternative SW-I-No Further
Action
Alternatives for surface water were previously evaluated under the Surface Water
Removal Action Engineering Evaluation and Cost Analysis. During the RIfFS process,
the SWRA was evaluated for incorporation into the overall selected remedy. This
evaluation included an assessment of the effectiveness, implementability, and cost of the
SWRA, as well as the statutory considerations in CERCLA Section 121(b)(1). Upon the
initial screening of the alternatives, it was determined that the SWRA met the evaluation
criteria and should therefore be retained for detailed analysis as the No Further Action
alternative.
This alternative includes the O&M of the barrier wall; the SWRA, including both the
c:ollection system and upgrades to the GWTP; and the enforcement of the existing institu-
tIonal controls, such as fencing and signage, and restrictions on land uses, site access,
well drilling, and residential development. Additional measures would include construc-
DENlOOlS3AA.WPS
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tion of wetlands in accordance with the SWRA Consent Order and implementation of a
long-term monitoring program.
The ground-water barrier system and GWTP is an interim remedial measure implemented
pursuant to Consent Order, EPA Docket No. CERCLA VllI-83.{)6 (signed January 10,
1984) and is designed to reduce the northern offsite migration of contaminated ground
water via the unnamed creek alluvium and weathered bedrock. The barrier wall consists
of a 1,OOO-foot-long drain backed by a 30-foot-deep compacted clay barrier located
immediately north of the Section 6 northern boundary. The drain and barrier function as
a subsurface collection system. Water collected in this system is pumped to the GWTP
to treat volatile and semivolatile organic compounds. The treated effluent is released via
an injection trench into the alluvium of unnamed creek north of the barrier wall. The
GWTP was modified as part of the SWRA and may be further upgraded, based on pilot-
scale testing, to remove iron, manganese, vanadium, or other contaminants, if these are
detected above performance standards. These upgrades could include biological treatment
or ion exchange.
The SWRA interim remedial measure includes a seepage collection system in the
Section 6 portion of the unnamed creek drainageway, closure of Ponds 3 and 4, and
modification of the existing GWTP. The SWRA was completed in 1992 and is currently
operational.
The SWRA collection system consists of a subsurface drainage system wrapped in
geotextile that was constructed within the unnamed creek channel in Section 6. The
collection system is designed to keep the contaminated alluvial flows separate from the
uncontaminated surface water runoff. The system collects the alluvial flows and directs
them toward the barrier wall. The drainage system and the Section 6 sediments located
within unnamed creek have been covered by a compacted, fine-grained soil layer, which
has been graded into a broad, gently sloping drainage swale. This relatively low
permeability soil layer keeps the precipitation primarily as surface runoff and prevents it
from contacting the covered sediments or entering the drainage system. The
uncontaminated surface water flows over the collection system and eventually empties
into Murphy Creek via the unnamed creek segment in Section 31.
Placement of a compacted 4-foot soil cover over the landfill mass in Section 6 was
initiated in 1987. The landfill mass cover was completed in 1992, vegetated, and graded
to provide control of surface water runoff. The cover efficiently drains precipitation-
derived runoff from the landfill, thereby significantly reducing the potential for
infiltration of the runoff into the landfill mass.
Under the preferred alternative, annual monitoring of the surface water runoff into the
unnamed creek drainage would be conducted to evaluate the potential for contaminant
migration, although the exposure pathway to the Section 6 sediments has been eliminated
as a result of the soil cover over the SWRA collection system. An automated surface
water runoff sampler would be installed in the drainage in Section 6 for the purpose of
monitoring offsite contaminant migration.
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Before the SWRA was implemented, the natural storm water runoff and any underground
seepage in the unnamed creek basin in Section 6 constituted the contamina~ media.
The contaminated surface water medium, as it existed before the construction of the
SWRA collection system, has been eliminated. The SWRA collection system effectively
limits the contaminated seepage as an underground flow, and keeps it from mixing with
surface water. The SWRA collection system also isolates the sediments from the surface
water and provides a control on the sediment contamination migration. The SWRA
collection system covers an area of approximately 4.8 acres.
The treatment of water in the upgraded treatment plant includes aerobic biodegradation
treatment to reduce the biological oxygen demand (BOD). Although the system is not
specifically designed to remove particular organic compounds, significant degradation of
phenols, ketones and other biodegradable organic compounds is expected in the system.
The biodegradation system would be incorporated in the overall treatment train only if
EPA determines that phenols and ketones are anticipated based on the early warning
monitoring data from the access well. If iron, manganese, and vanadium are detected in
the early warning monitoring system in quantities above the performance standards, they
would be precipitated from the water by addition of potassium permanganate. The metals
precipitation module has not been incoIJ>9rated into the GWTP at the present time.
Next, the water is air-stripped to remove volatile organic compounds. The off-gases
from the stripper are then passed through a vapor-phase activated carbon bed to adsorb
stripped organics. Clean off-gas is vented to the atmosphere.
Stripper bottoms or residuals may contain organics that are not biodegradable or strip-
pable to any significant extent; therefore, the stripper effluent is passed through a bed of
liquid-phase carbon to adsorb these organics. The effluent from the liquid-phase carbon
polishing step must meet the performance standards for injection downgradient of the
barrier wall.
The chemical composition of the influent to the treatment plant is assumed to be
compounds detected in the seepage water, ground water, and in waste-pit liquids. These
chemicals consist of volatile and semivolatile organics, iron, manganese, and vanadium.
Existing data from the treatment plant show removal efficiencies of 95 percent or greater.
Based on these measurements, approximately 80 pounds of contaminants would be
removed annually (assuming operation at 13 gpm).
The treatment plant has been designed for a combined seepage/ground water inflow of
30 gallons per minute (gpm) with flexibility to handle flows from 10 to 50 gpm. The
treatment process has been designed with flexibility to handle a wide range of chemicals
and concentrations that might need to be treated in the future.
The SWRA has been designed and constructed to collect and treat contaminated seep-
age an.d ground water for at least 30 years. It is anticipated that this system will be in
o~ration ~ long as there is contaminated seepage and/or ground water. If used,
bIodegradation and permanganate oxidation treatment would produce treatment residuals
DENlOOlS3AA.WPS
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or sludge which would be periodically dewatered, and drummed. The sludge would be
tested to determine the disposal options. If the sludge tests to be hazardous, it would be
disposed of in a RCRA Subtitle C facility; otherwise, it would be disposed of in the
Section 31 landfill.
Based on historic data from surface water in the unnamed creek onsite, risks were esti-
mated as 8 x 104 for ingestion by a child in the future on site residential setting. The
SWRA collection system has eliminated the initial risk from the surface water because
contaminated surface water does not exist anymore. Contaminated underground
seepage is treated in the GWTP to meet the SWRA ARARs. Thus, the risk from surface
water has been eliminated and would continue to be eliminated with this approach.
Treatability testing was performed to aid in the design of the original GWTP, modifica-
tion to the GWTP for the SWRA, and to test the compatibility of SWRA collection
system materials with the contaminated seepage.
Except for the automated runoff sampler and construction of new wetlands, there are no
initial measures to implement in this alternative because the SWRA has already been
implemented and is currently operational. The sampler would be installed within the first
year. A location and schedule for constructing the new wetlands would be determined by
EP A during the design phase.
Land use restrictions regarding use of the site surface, surface water, and ground water
would be continued. The GWTP effluent would meet the ARARs for the SWRA as
updated in this ROD; therefore, the residual levels would comply with performance
standards.
The following major ARARs were identified for this alternative:
DENlOOIS3AA.WPS
.
Colorado Water Quality Control Act (S CCR 1002-8), Colorado Basic
Standards for Ground Water, Classifications and Water Quality
Standards for Ground Water: These regulations establish standards for
both classified and unclassified ground water. The standards would be
applicable because ground water (within non-alluvial and alluvial aquifers)
near the Lowry Site and ground water (within alluvial aquifers) within the
Lowry Site have been classified for domestic and agricultural use-quality.
Under this alternative, ground water would be treated to meet these
standards and then discharged to the shallow ground-water system.
.
Safe Drinking Water Act, National Primary Drinking Water
Regulations (40 CFR Part 141) and the Colorado Primary Drinking
Water Regulations (S CCR 1003-1): These regulations would be relevant
and appropriate because the shallow and deep ground water in the vicinity
of the Lowry Site is being used or may be used in the future as a source of
water for a public water system or private supply wells. Under this
alternative, treated ground water from the treatment plant would be
8-41
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injected into the shallow ground-water system in compliance with these
. requirements.
.
Safe Drinking Water Act, National Secondary Drinking Water
Regulations (40 CFR Part 143): These regulations establish welfare-
based standards for public water supply systems and have been adopted by
the State of Colorado under the basic standards for ground water. The
regulations would be relevant and appropriate because the shallow and deep
ground water in the vicinity of the Lowry Site is being used or may be
used in the future as a source of water for a public water system or private
supply wells. Under this alternative, ground water would be treated to
meet these standards and then discharged to the shallow ground-water
system in compliance with these requirements.
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (5 CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations are applicable for treatment plant
operations and would be met by this alternative.
.
Executive Order 11990, Protection of Wetlands would be applicable
because wetlands have been identified at the Lowry Site and were
destroyed as part of construction of the SWRA. New wetlands would be
constructed under this alternative to mitigate the loss of wetlands, thus
meeting the requirements of this Executive Order.
Excavated sediments would be transported off site for disposal in accordance with EPA's
Offsite Policy (40 CFR Section 300.4(0).
The total 3D-year present worth cost of this alternative is $12,190,000 with capital costs
of $41,000 and annual O&M costs of $790,000. The estimated time to implement the No
Further Action alternative is 1 year.
The SWRA, GWTP and landfill cover remedies were developed and implemented earlier,
independent of the alternatives developed for OUs 4&5. Therefore, the capital expen-
ditures associated with these remedies are not considered part of the surface water
alternatives developed in conjunction with the sitewide remedy and presented here.
However, because the upgrade and O&M of these facilities are consistent with the
sitewide remedial strategy, their costs are included in the No Further Action alternative.
8.4.4.6 EPA's Prefen-ed Alternative-Section 6 Sediments
Alternative SED6-1- No Further Action
The major feature of Alternative SED6-1, the No Further Action alternative for Section 6
sediments, is the SWRA as described in Alternative SW -1.
DEN 1 00 1 53AA.WPS
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Although the exposure pathway to the Section 6 sediments has been eliminated as a result
of the soil cover over the SWRA collection system, annual monitoring of the surface
water runoff into the unnamed creek drainage would be conducted to evaluate the
potential for contaminant migration. For the purpose of monitoring offsite contaminant
migration, one automated surface water runoff sampler would be installed in the drainage
in Section 6 to monitor runoff.
Before implementation of the SWRA, sediments in the approximately 2,8QO-foot-Iong
portion of the unnamed creek in Section 6 constituted the contaminated media. However,
during the construction of the SWRA collection system, a polypropylene geotextile
blanket and a 2-foot-thick low-permeability soil cap were placed over the sediments. As
a result, the sediments are no longer exposed.
There would be no treatment components associated with this alternative.
The containment component for the Section 6 sediments includes a geotextile and a low-
permeability soil cap in order to keep the surface water runoff from contacting the sedi-
ments or mixing with the contaminated leachate from the landfill mass. The type of
storage utilized by this alternative is in-place containment under geotextile and soil cap.
The areal extent of the sediments is conservatively estimated at 320,000 square feet. The
volume of the sediments is unknown.
Based on the historic data on sediments, a maximum excess cancer risk of 9 x 10-6 was
calculated for ingestion of sediments by a child. By covering the sediments with a gee-
textile and a soil cap, the risk has been eliminated. Geotechnical properties of the sedi-
ments were determined during the design of the SWRA collection system. No other
treatability studies were carried out for the sediments. Existing institutional controls,
including site fencing, signage, site access, and land use restrictions would be continued
under this alternative. Because the sediments would not be treated under this alternative,
the residual levels would be the same as the initial levels. However, exposure pathways
would be incomplete.
There are no major action-, location-, or chemical-specific ARARs identified for this
alternative.
The RAOs would be achieved for this alternative through elimination of exposure to the
sediments. Neither toxicity nor volume of the contaminants would be reduced by this
alternative. The potential for mobilization of the contaminants would still exist, since the
underground seepage would flow through the sediments. However, the seepage would be
treated in the GWTP to meet the performance standards.
The total 3O-year present worth cost of this alternative is $250,000 with capital costs of
$16,000 and annual O&M costs of $350,000. Except for the automated runoff sampler,
there would be no initial measures to implement in this alternative. The sampler would
be installed within the first year.
DENlOOI53AA.WP5
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8.4.4.7 Section 6 Sediments Alternative SED6-2-Access Restrictions
Alternative SED6-2 for Section 6 sediments would include the installation of
6 145 linear feet of 6-foot-high chain link fence topped with three strands of barbed wire
a.:.ound the unnamed creek to restrict access to the SWRA collection system cover over
the sediments. The SWRA collection system would also be an integral part of the
alternative as described in Alternative SW -1.
Although the exposure pathway to the Section 6 sediments has been eliminated as a result
of the soil cover over the SWRA collection system, annual monitoring of the surface
water runoff into the unnamed creek drainage would be conducted to evaluate the
potential for contaminant migration. For the purpose of monitoring offsite contaminant
migration, one automated surface water runoff sampler would be installed in the drainage
in Section 6 to monitor runoff.
The SWRA cover would be inspected after each significant rainfall or runoff. Surface
water runoff would be monitored annually so that EP A could determine whether
contaminants were migrating offsite.
Contaminated media include sediments in the approximately 2,800-foot-Iong portion of
the unnamed creek in Section 6. During the construction of the SWRA collection system,
a polypropylene geotextile blanket and a 2-foot-thick low permeability soil cap were
placed over the sediments. As a result, the sediments are no longer exposed.
There would be no treatment components associated with this alternative.
The containment component for the Section 6 sediments would include a geotextile and a
low permeability soil cap in order to keep surface water runoff from contacting
contaminated sediments or mixing with the contaminated leachate from the landfill mass.
Additionally, the fence around the Section 6 area would further restrict access and
potential exposure to the sediments. The fence would cover an area conservatively
estimated at 320,000 square feet. The exact area and volume of the sediments are
unknown. The type of storage utilized by this alternative would be in-place containment
under geotextile and soil cap.
Based on the historic data on sediments, a maximum excess cancer risk of 9 X 10-6 was
calculated for ingestion of sediments by a child. By covering the sediments with a geo-
textile and a soil cap, the risk has been eliminated. Geotechnical properties of the
sediments were determined during the design of the SWRA collection system to evaluate
the use of sediments as a daily cover in the landfill. The sediments were deemed unsuit-
abl~ for use as a daily cover. No other treatability studies were carried out for the
sedIments. E~~ting institutional controls including site fencing, signage, site access, and
land use restrictions would be continued under this alternative. The additional fencing of
6,145 feet around the unnamed creek would further restrict access to the sediment area.
DENlOOIS3AA.WPS
8-44
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The residual levels would be the same as the initial levels, since the sediments would not
be treated under this alternative. In any event, exposure pathways would be incomplete.
The following major ARARs have been identified for this alternative:
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (5 CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations would be applicable during
construction activities and would be met by this alternative.
The RAOs would be achieved for this alternative through elimination of exposure to the
sediments. Neither toxicity nor volume of the contaminants would be reduced by this
alternative. The potential for mobilization of the contaminants would still exist, since the
underground seepage would flow through the sediments. However, the seepage would be
treated in the GWTP to performance standards.
The total 30-year present worth of this alternative is $450,000 with capital costs of
$93,000 and annual O&M costs of $23,000. The estimated time to implement Alterna-
tive SED6-2 would be 1 year. Except for the automated runoff sampler and the fence,
there are no initial measures to implement in this alternative. The sampler and the fence
would be installed within the first year.
8.4.4.8 EP A's Prefe"ed Alternative - Section 31 Sediments
Alternative SED31-1-No Further Action
Alternative SED31-1, The No Further Action alternative, would include continuation of
the existing site fencing, signage, site access, and land use restrictions. The contami-
nated media are the sediments in the approximately 2,660-foot-Iong portion of the
unnamed creek in Section 31, from the southern boundary of Section 31 up to the conflu-
ence with Murphy Creek.
Annual monitoring of the surface water runoff into the unnamed creek drainage would be
conducted to evaluate the potential for contaminant migration. For the purpose of
monitoring off site contaminant migration, one automated surface water runoff sampler
would be installed in the drainage in Section 31.
There would be no treatment or containment components associated with this alternative.
Approximately 23,700 cubic yards of the untreated sediments would be left in place under
this alternative. The risk would remain unchanged, since no treatment or containment of
the sediments would be involved.
DENlOO153AA.WPS
8-45
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The Baseline Risk Assessment assumed the SWRA was no longer operational and future
residences were built in Section 31. An excess cancer risk of 7 x 10-s was calculated for
ingestion of sediments by a chil~. The ri~k wo~ld not be red~ced by this alte~a~v~.
However the risks associated WIth potential sedIment contammant exposures IS Within the
, .
acceptable excess cancer risk range. A noncancer HI greater than 1 was estimated for a
future resident child that ingests and inhales sediments from this portion of Section 31.
The three chemicals that contribute to this HI have different target organs; therefore, the
III would be below 1 if the chemical-specific target organ was considered. In addition,
land use restrictions would prevent residential development on this Section. Thus, the No
Further Action alternative for Section 31 would be protective of human health and the
environment.
No treatability testing was conducted during the RIfFS for the sediments, because the
alternatives considered are proven technologies. The residual levels would be the same
as the initial levels, because the sediments would not be treated under this alternative.
There are no action-, location-, or chemical-specific ARARs identified for this
alternative.
The RAOs would be achieved for this alternative through the existing restrictions on
access and land uses. Sediments would remain in place, but would be of concern only
for a residential exposure (resident in Section 31). Toxicity, volume and mobility of the
contaminants would not be reduced by this alternative.
The total 3D-year present worth of this alternative is $300,000 with capital costs of
$22,000 and annual O&M costs of $18,000. The estimated time to implement Alterna-
tive SED31-1 would be 1 year.
8.4.4.9 Section 31 Sediments Alternative SED31-2 - Access Restrictions
and Capping
Alternative SED 31-2 for Section 31 Sediments would include a cap over the sediments,
and approximately 5,400 linear feet of fence around the unnamed creek to restrict access
to the sediments. Sediments in the approximately 2,660-foot long portion of the unnamed
creek in Section 31, from the southern boundary of Section 31 up to the confluence of
Murphy Creek constitute the contaminated media.
The cap would consist of approximately 10,800 square yards of a single layer of synthetic
~er (60-mil high-density polyethylene) over the unnamed creek drainageway in Sec-
ti~n 31, overlain. with a 6-inch layer of gravel (approximately 1,700 cubic yards) and a
9-~ch layer of nprap (approximately 2,500 cubic yards). A total of 1.47 acres of the
drainageway wo~l~ be capped. Grading operations before the placement of the liner
would create fugItive dust. The dust would be suppressed with water sprays.
DENl00153AA.WPS
8-46
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Grading might require removal of some sediments. These sediments would be character-
ized to determine if they could be disposed of in a RCRA Subtitle D landfill. Capping of
the sediments would claim approximately 1.27 acres of wetlands. New wetlands would
be created in the Murphy Creek drainage or in an offsite area appropriate for wetland
development. Approximately 5,400 linear feet of 6-foot-high chain link fence topped
with three strands of barbed wire would be installed to restrict access to the sediments
along the unnamed creek segment in Section 31 up to the confluence with Murphy Creek.
The alternative would also include maintenance of the cap, wetlands, new site fencing,
signage, site access, and land use restrictions.
Annual monitoring of the surface water runoff into the unnamed creek drainage would be
conducted to evaluate the potential for contaminant migration, although the exposure
pathway to the Section 31 sediments would have been eliminated as a result of the cap
over the sediments. For the purpose of monitoring off site contaminant migration, one
automated surface water runoff sampler would be installed in the drainage in Section 31
to monitor runoff.
There would be no treatment components associated with this alternative.
The Section 31 sediments would be contained and covered with a liner in order to keep
the surface water runoff from contacting the sediments. Additionally, the fence around
the sediment area would restrict access to the sediments. Approximately 23,700 cubic
yards of the untreated sediments would be left in place under this alternative. The risk
prior to and following containment would remain unchanged, since no treatment of the
sediments would be involved. Because the sediments would be covered, the exposure
pathway would be incomplete. The long-term risks would be essentially eliminated due
to capping of the sediments and access restrictions. However, there would be a potential
for the short-term risk from fugitive dust generated during the installation of the fence
and the cap. Treatability testing was not conducted during the RIfFS for the sediments,
because the alternatives considered are proven technologies.
The initial measures to implement in this alternative are the new chain link fence, syn-
thetic liner and gravel and riprap, creation of new wetlands, and the automated runoff
sampler.
The following major ARARs have been identified for this alternative:
.
Colorado Air Quality Act/Colorado Air Pollution Regulations (5 CCR
1001): These regulations establish standards for air emissions from
stationary sources. These regulations would be applicable during
construction activities and would be met by this alternative.
.
Executive Order 11990, Protection of Wetlands: This requirement
would be applicable to protection of designated wetlands. Wetlands have
been identified at the Lowry Site and would be destroyed in capping the
sediments. New wetlands would be constructed under this alternative to
DENlOOlS3AA.WP5
8-47
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mitigate the loss of wetlands. Creation of new wetlands would comply
with the requirements of this Executive Order.
.
Clean Water Act (40 CFR Part 230): This requirement establishes
standards for construction activities affecting waters of the United States.
This Act is applicable because this alternative would involve disturbance of
potential wetlands and placement of a cap in the unnamed creek. Any
substantive permit requirements would have to be met.
The RAOs would be achieved for this alternative through a reduced potential for long-
term exposure to the sediments due to the Cap over the sediments as well as fencing off
of the area.
Grading, potential removal of some sediments, and installation of the new fence would
create a potential for occupational (short-term) exposure and habitat disturbance. Neither
toxicity nor volume of the contaminants would be reduced by this alternative. The
potential for mobilization of the contaminants would be greatly reduced due to the
isolation of sediments from the surface water runoff.
The total 30-year present worth of this alternative is $1,215,000 with capital costs of
$400,000 and annual O&M costs of $53,000. The estimated time to implement Alterna-
tive SED31-2 would be 1 year.
8.4.4.10 Section 31 Sediments Alternaiive SED31-3-Excavation and
Landfill
Alternative SED31-3 would include excavation and landfilling of 23,700 cubic yards of
the Section 31 sediments. The excavation would be carried out in the unnamed creek
drainage in Section 31 up to the confluence with Murphy creek (approximately
2,660 feet) at an average width of 24 feet and down to the depth of the water table
(average 10 feet). The sediments would be landfilled in the existing Section 31 landfill,
which complies with the current RCRA Subtitle D requirements. An area of
approximately 1.47 acres, and a volume of 23,700 cubic yards are calculated for the
sediments.
Disposal in a RCRA Subtitle C landfill is not anticipated based on the available contami-
nant and concentration information for the sediments. However the sediments would be
,
tested for RCRA hazard characteristics prior to disposal. If determined necessary by
EP A, excavated sediments would be transported offsite for disposal in accordance with
EPA's Offsite Policy (40 CPR Section 300.400). Following excavation, the area would
be backfilled with clean soil, compacted, graded and vegetated.
Excavation of the sediments would claim approximately 1.27 acres of wetlands. New
wetlands would be created in the Murphy Creek drainage or in an off site area appropriate
for wetland development.
DENlOO153AA.WPS
8-48
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The existing institutional controls such as fencing, signage, site access and land use
restrictions would be maintained under this alternative.
Annual monitoring of the surface water runoff into Murphy Creek would be conducted to
evaluate the potential for contaminant migration, although the Section 31 sediments would
have been excavated and landfilled. For the purpose of monitoring offsite contaminant
migration, one automated surface water runoff sampler would be installed in the drainage
in Section 31.
There would be no treatment components of this alternative.
Excavation and land filling of the sediments would result in the containment of the con-
taminants in the RCRA Subtitle D facility in Section 31. The excavated material would
be disposed of as solid waste rather than being used as a daily cover material because the
sediments are not expected to be of a quality appropriate for use as daily cover.
Approximately 23,700 cubic yards of sediments would be excavated and landfilled in the
RCRA Subtitle D facility in Section 31. No sediments would be left in place; therefore,
risk would be eliminated.
The Baseline Risk Assessment estimated a maximum excess cancer risk of 7 x 10-5 from
ingestion of sediments by a child in a residential setting. All long-term risk (cancer and
noncancer) would be essentially eliminated due to excavation and landfi1ling of the
sediments. A short-term risk would be created from fugitive dust generation during the
excavation and materials handling activities. Treatability testing was not conducted
during the RIfFS for the sediments because the alternatives considered are proven
technologies. Excavation and land filling of the sediments would be completed in three to
6 months. Installation of the automated surface water sampler would be achieved within
the first year. There would be no residua1levels remaining from removal of the
sediments.
Major ARARs for this alternative are the same as for Alternative SED31-2 and would be
met by this alternative using similar methods.
Although excavation and transport of the sediments to the active landfill area in
Section 31 would create a potential for occupational (short-term) exposure and habitat
disturbance, the RAOs would be achieved for this alternative through elimination of
potential for long-term exposure to the sediments. Neither toxicity nor volume of the
contaminants would be reduced by this alternative. The potential for mobilization of the
contaminants would be significantly reduced due to the disposal in a RCRA Subtitle D
landfill.
The total 30-year present worth of this alternative is $1,235,000 with capital costs of
$620,000 and annual O&M costs of $40,000. The estimated time to implement Alterna-
tive SED31-3 would be 1 year.
DEN 1 OO153AA.WPS
8-49
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Page 1 or~
Table 8-1
ARARs for OUs 1&6
.
DescripCion Evaluation
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Safe Drinking Water Ad
Establishes health-based standards for These regulations are relevant and appropriate be<:ause the
public drinking water systems (MCLs). shallow and deep ground water in the vicinity of the Lowry
Site is being used or may be used in the future as a source
of water for a public water system or private supply wells.
Treated ground water from the treatment plant would be
injected into the shallow ground-water system. The
standards are pertinent to treatment plant effluent at the
point of injection as well as within the ground water at the
compliance boundary.
Establishes drinking water quality goals Non-zero MCLGs are relevant and appropriate since
set at levels of no known or anticipated shallow and deep ground water in the vicinity of the Lowry
adverse health effects, with an adequate Site is being used or may be used as a source of water for a
margin of safety (MCLGs). public water system or private supply wells.
Federal Water PoDution Control Ad (amended by the Clean Water Ad)
Establishes toxic pollutant effluent Relevant and appropriate for treatment plant effluent
standards for six groups of toxic because compound groups were detected in waste pit liquids
pollutants from manufacturers, and unnamed creek and Murphy Creek discharges to the
formulators, and applicators who South Platte River, which is a navigable water.
develop or use these compounds and
discharge to navigable waters.
Solid Waste Disposal Ad-RCRA Subtitle C
Sets ground-water protection standards The State of Colorado operates an approved delegated
for land disposal units. program for this portion of RCRA. See requirements under
Colorado Hazardous Waste Act. Relevant and appropriate
because the landfill operates like a hazardous waste
management unit.
....:.:..:.::.:...y[[[~~~Y$~I~;'::~jj~#.ffit:!:::;::::::::;:::::.!;::::::::::::!:::::!:;:j':::::::!::::!:!!:::::::;:::::::::::::!::!j:::::::::::::;::t::::::;::::::::::i::::::::!::::;:
Colorado Bazardons Waste Ad
Citation
.::6?tf\ft?:. ..
.....
..
. ..
...
40 CFR Part 141
Subpart B
40 CFR Part 141
Subpart F
40 CFR Part 129
Toxic Pollutant Effluent
Standards
40 CFR Part 264
Subpart F
6 CCR 1007-3 Part 264.94
Colorado Rules and
Regulations Pertaining to
Hazardous Waste-Ground
Water Protection Standard
Establishes concentration levels for 14
chemicals in ground water.
The concentration limits are relevant and appropriate to
ground water at the compliance boundary for ground water
and treatment plant effluent.
Colorado Water Quality CoDtroI Ad
Establishes specific limitations on point Relevant and appropriate for discharge from treatment plant.
source discharges of wastewaters into
state waters and from specified industry
sources, specifies sampling and
analytical requirements.
Establishes health-based standards for
public water systems.
5 CCR 1002-3
Regulation on Effluent
Limitation
5 CCR 1003-1
Colorado Primary Drinking
Water Regulations
These regulations are relevant and appropriate because the
shallow and deep ground water in the vicinity of the Lowry
Site is being used or may be used in the future as a source
of water for a public water system or private supply wells.
-------
Page 2 orsl
Table 8-1
ARARs for OUs 1&6
Citation
Description Evaluation
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:"""':"':""':',':':':"':':':':':'::"':':'-:"'"'.:.;.;.'.;.'.'.','.:.:.:.'.:.:-:.',',,',',
Establishes a system for classifying These regulations establish standards for both classified and
ground water and sets water quality unc1assified ground water. The standards are applicable
standards for such c1assifications. because ground water (within non-alluvial and alluvial
aquifers) near the Lowry Site and ground water (within
alluvial aquifers) within the Lowry Site have been classified
for domestic and agricultural use-quality. Ground water
would be treated to meet these standards and then
discharged to the shallow ground-water system.
Murphy Creek and the unnamed creek are classified and
regulated as tributaries of the South Platte River Basin
(Stream Segment 16). Segment 16 is classified as
Recreation Class 2, Warm Water Aquatic Life Class 2, and
Agricultural Supply. Because of this c1assification,
statewide interim organic pollutant standards for aquatic life
segments (Section 3.1.11 and Table C) are applicable to the
remedy. If surface-water discharge results from injection of
the treated water, surface water standards will be established
based on the most stringent surface water ARAR.
Murphy Creek and the unnamed creek are classified and
regulated as tributaries of the South Platte River Basin
(Stream Segment 16). Segment 16 is classified as
Recreation Class 2, Warm Water Aquatic Life Class 2, and
Agricultural Supply. Based on the regulations, numeric
standards for protection of these three c1assified uses are
applicable. Chemical-specific standards established for
Stream Segment 16 are applicable to the remedy. If
surface-water discharge results from injection of the treated
water, surface water standards will be established based on
the most stringent surface water ARAR.
Colorado Air Quality AdJ Air PoDutioo Regulations
Establishes standards for emissions of These regulations are applicable because air emissions will
particulates, smoke, carbon monoxide, occur at the ground-water treatment plant and due to
and sulfur oxides. constnJction activities. These regulations would be met for
the air stripper/carbon polishing treatment process and
during constnJction. Regulations for opacity and offsite
transport of visible fugitive emissions are applicable and
must be auained during constnJction activities resulting in
disturbance of 5 acres or more in attainment areas or one
acre in nonauainment areas. The Lowry Site is in an
auainment area for sulfur oxides and lead and in a
nonattainmentarea for PM 10, ozone, and carbon
monoxide.
5 CCR 1002-8
Section 3.11.0
Colorado Basic Standards
for Ground Water
and Section 3.12.0
C1assifications and Water
Quality Standards for
Ground Water
5 CCR 1002-8
Section 3.1.0
Basic Standards and
Methodologies for Surface
Water
Establishes basic standards and a
system for classifying surface waters of
the State, assigning standards, and
granting temporary variances for the
standard.
5 CCR 1002-8
Section 3.2.0
Classifications and Numeric
Standards
Used in conjunction with Basic
Standards and Methodologies Section
3.1.0. South Platte River Standards
(Section 3 .8) establish numeric
standards for the South Plane River
Basin based on use classifications for
stream segments.
5 CCR 1001-3
Regulation No.1
5 CCR 1001-4
Regulation No.2
Sets limits on odorous air contaminants
and particulates.
These regulations are applicable because air emissions will
occur at the site during all activities. Activities regulated
include activities such as soil movement or treatment plant
air emissions. These regulations would be met for all
activities including the air stripper/carbon polishing
treatment process and movement of soil for construction of
barrier walls.
8-51
DEN10015382.WP5
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Table 8-1
ARARs for OUs 1&6
Page 3 ofS
Citation Description Evaluation
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-::;:::::-:.::':::.:. . ..:::.:::::::::
5 CCR 1001-10 Sets emission control requirements for These regulations are applicable because air emissions occur
Regulation No.8 hazardous air pollutants. at the treatment plant. These regulations would be met for
the air stripper/carbon polishing treatment process. The
lead standards are applicable because they are ambient
standards that apply to all sources. The beryllium
provisions set out emission limitations for stationary sources
that are applicable for all sources. The hydrogen sulfide
standards are applicable to any actions emitting hydrogen
sulfide. The mercury standards are applicable if wastewater
treatment plant sludge is dried or incinerated.
Establishes ambient standards for SO., These regulations are applicable because air emissions OCcur
TSP, N<>V CO, ozone, and PM 10. at the treatment plant. These regulations would be met
because these parameters are not expected to be present. If
these parameters are detected above the regulated levels,
action will be taken to correct the problem.
!f:::::::::!::::::::"::':::::":":i:?::::::::::::.:).......::::::m:i':':::::::::?:!:::::I::::::::~#.S$~~~:!!~8¥~~~?!::::::,::::::::::::':::::::':i::::::::::::::::j::::::!:::j:::::::':::!:::,::i:!!:!,I::"!!!:::::):i'::::!:::::(:
SoJid Waste Dtiposal Act-RCRA Subtitle C Regulations
Establishes hea1th-based air standards. TBCs. These standards were used to design the SWRA
when considering air pollution controls for the water
treatment plant. The plant will continue to meet these
standards.
5 CCR 1001-14
Ambient Standards
MassachuseUs
Allowable Ambient Levels
(AALs) and Threshold
Effects Exposure Limits
(I'ELs)
40 CFR Part 260-261
Identification and Listing of
Hazardous Waste
40 CFR Part 262
Standards Applicable to
Generators of Hazardous
Waste
40 CFR Part 264 Subparts
B, C, and D
Standards for Owners and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
DEN10015382.WP5
Defines those solid wastes that are
subject to regulation as hazardous
Wastes under 40 CFR Parts 262-265
and Pans 124, 270, 271.
Establishes standards for RCRA
generators.
Establishes minimum standards that
define the acceptable management of
hazardous waste for owners and
operators of facilities which treat,
store, or dispose of hazardous waste.
The State of Colorado has an approved delegated program
for this portion of RCRA. The regulations are applicable
for purposes of determining whether any of the materials
being treated or disposed are hazardous wastes. Materials
may also be compared to the waste listings to determine
whether any of the materials are sufficiently similar such
that RCRA regulations are relevant and appropriate.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment plant residuals, and waste generated during
construction activities for the barrier walls. Therefore,
waste generated must meet these standards which include
testing per 40 CFR Part 261, temporary tanks or containers,
inspection and leak detection, and accumulation time. The
State of Colorado has an approved, delegated program
under RCRA.
Because remediation activities constitute treatment and
storage activities (ground-water treatment plant and residuals
management), and because the water to be treated is
sufficiently similar to RCRA hazardous waste such that use
of the requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment component of the remedy (mcluding residuals
management). Thus, treatment of the ground water must
meet these standards, which include waste analysis, site
security, eJDCIgency control and response equipment,
personnel training, contingency planning and
implementation.
8-52
-------
Citatioa
~fi\j~j~\~j[~\j\\\jrf~~~fj1~t~rr[~~~[~\\~~~ff\~jr~1\V~:
40 CFR Pan 264
Subpart F
Table S-l
ARARs for OUs 1&6
Description
:::::::::::::::::::::::::::::::::ItA~~~~~:::~8f~~::~~~:::::.... ...::;:/))/ ...:.. ... ..:/i
Sets ground-water protection standards The State of Colorado operates an approved delegated
for land disposal units. program for this portion of RCRA. See the requirements
under Part 264.94 of the Colorado Hazardous Waste Act.
Relevant and appropriate to ground water under the site
because the landfill operates like a solid waste management
unit. Therefore, ground-water programs must meet these
standards, which include a monitoring and response
program that includes detection monitoring to identify the
presence of hazardous constituents in ground water;
compliance monitoring to determine whether the agency-
specified ground-water protection standard is being met at
the identified compliance point; and corrective action that
prevents hazardous constituents &om exceeding the
established concentration limits beyond the point of
compliance.
Because ground-water treatment constitutes treatment of a
waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is wen suited to the
situation, the requirement is relevant and appropriate to the
ground-water treatment component of the remedy.
Therefore, closure and post-closure care for this treatment
system must meet these standards which include removal of
waste, waste residues, contaminated system components,
and contaminated subsoils; or closure with wastes and/or
contamination in place with containment systems and post-
closure care to include ground-water monitoring and
inspection and maintenance on containments and monitoring
systems.
Because ground-water treatment includes storage in
containers of a waste that is sufficiently similar to RCRA
hazardous waste such that use of the requirement is wen
suited to the situation, the requirement is relevant and
appropriate to the ground-water treatment component of the
remedy. Therefore, container storage at the ground-water
treatment plant must meet these standards, which include
maintaining wastes in containers that are in good condition
and compatible with the wastes they contain, providing a
containment system, managing ignitable and reactive Wastes
away &om the property line, keeping incompabole wastes in
separate containers and containment systems, and at closure
removing an wastes and decontaminating structures and
equipment.
Because ground-water treatment includes storage in tanks of
a waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is wen suited to the
situation, the requirement is relevant and appropriate to the
ground-water treatment component of the remedy.
Therefore, tank storage at the ground-water treatment plant
must meet these standards, which include secondary
containment; spill and overflow controls; removal &om
service if there is a leak, spill, or the tank is unfit for use;
and at closure have an wastes removed and also remove or
decontaminate waste residues, containment system, soils,
structures, and equipment.
40 CFR Part 264 Subpart G Closure and post-closure care.
40 CFR Pan 264
Subpart I
40 CFR Pan 264
Subpart J
DENlOO15382.WP5
Sets operating and performance
standards for container storage of
hazardous waste.
Sets operating and performance
standards for tank storage of hazardous
waste.
8-53
Page 4 0(8
Evaluation
-------
Page 5 or~
Table 8-1
ARARs for OUs 1&6
.
Description EvaluatiOD
. . ..':......;~r:~:.~~;J~~~~~if~~:~;:f:~~!l*i~~;~~~!:~}!:~:~!!!~~@!I::~::r!!~~~!:i;~~:t!!:!!:!~r::!:!i!:~!j!t!;!!::;:!:!i!ij!::!!!i!!!!!!!::!::!i:!:~:!::::::i:
Sets standards for mixing and treatment Because the ground-water treatment plant will mix and treat
of contalJliDated soils or the mixing and potentiaDy incompatible, reactive, or ignitable wastes which
treatment of potentially incompatible, may be similar to hazardous wastes, the requirement is
reactive, or ignitable hazardous wastes. relevant and appropriate to the ground-water treatment
plant. Therefore, the wastes must be analyzed to determine
compatibility, reactivity, and ignitability before treatment in
the treatment plant.
Because residuals from the ground-water barrier waDs
construction and residuals from the ground-water treatment
plant operations will be land disposed, the requirement is
applicable. The materials must be tested to determine if
they are a characteristic hazardous waste (per 40 CFR. Part
262) and then must meet treatment requirements for land
disposal as required in the standards if they are hazardous
waste for which a treatment standard has been established.
For land disposal of residuals, ocher than soils, which are
DOt characteristic hazardous wastes, these requirements are
relevant and appropriate because the residuals are
sufficiently similar to listed hazardous waste such that use of
the requirements is weD suited to the situation.
FedenI Water PoIhdion Control Act (amended by the C1ean Water Ad)
Establishes requirements for Because stormwater discharges will occur from any
stormwater discharges related to treatment process areas constructed (such as the ground-
industrial activity. Stormwater runoff, water treatment plant), this requirement is applicable to
snow melt runoff, and surface runoff stormwater discharges. Therefore, stormwater discharges
and drainage associated with industrial must meet these standards which include sampliDg, analysis,
activity from remedial actions which and treatment requirements. Implementation and
discharge to surface waters shaD be enforcement has been delegated to the State of Colorado,
conducted in compliance with RCRA, see the Colorado Water Quality Control Act.
FWQC, CW A technology-based stan-
dards, Colorado surface water quality
standards, monitoring requirements,
and best management practices.
Establishes radionuclide concentration
limits for liquid effiuents from facilities
that extract and process uranium,
radium, and vanadium ores.
Citation
<.:::::::: -':':':';',':':',";'
""""'....{::::::::';:::{::;::::::;"';"
.....
..
40 CFR. 265.17
40 CFR. Part 268
Land Disposal Restrictions
Establishes prohibitions on land
disposal unless treatment standards are
met or a "DO migration exemption" is
granted.
40 CFR. Part 122
NPDES Stormwater
Regulations
40 CFR., Part 440
Effiuent Guidelines and
Standards for Ore Mining
and Dressing Point Source
Categories
Because the effiuent from the ground-water treatment plant
could have radionuclides sufficiently similar to those
regulated such that the requirement is weD suited to the
situation, the requirement is releVant and appropriate to the
ground-water treatment plant effluent. Therefore,
contingencies have been made for the early detection of
radionuclides and for a treatment process to be added to
treat radionuclides at the ground-water treatment plant.
Clean Air Ad
40 CFR. Part 61
National Emission
Standards for Hazardous
Air Pollutants (NESHAPs)
Establishes emission standards for
hazardous air poDutants from specific
sources.
Because the ground-water treatment plant has an air stripper
that is a source of air emissions, and this source is
sufficiently similar to source types in the regulations such
that use of the requirement is weD suited to the situation,
the requirement is relevant and appropriate to the ground-
water treatment plant. Therefore, the air stripper must meet
these standards which include treatment levels for arseoic,
beryllium, benzene, vinyl chloride and radionuclide
emissions.
DEN 1001 5382.WP5
8-54
-------
Table 8-1
ARARs for OUs 1&6
Page 6 of8
Citation DescripCion Evaluation
::::~::::::~:::::::n:~:~:~:::::::::~::::r:~~~:m:::::::::::::::::::~::f::~~:::~:i~::~~:~:~:::::~~~~:::~~~$~.fi~7f~#I.;;(~~~?:::~::::::::::::}::::: ....... .....: .:....: :......... .....:.
Safe Drinking Water Act
Establishes staDdards for construction Applicable to injection of water from treatment plant. The
and operation of injection wells. requirements include constructing, operating, and
Provides for protection of underground maintaining a well in a manner that does not result in
sources of drinking water. contamination of an underground source of drinking water
at levels that violate MCLs or otherwise affect the health of
persoos. These requirements will be met by ensuring the
effluent from the ground-water treatment plant meets
staDdards that are protective of human health (based on
MCLs and risk-based concentrations).
40 CFR. Parts 144-147
Underground Injection
Control Regulations
::I:::::::::::::::~:::::t:~:r::::::::::::::::::::::::r:::::::I:::;:::::\\:~~~~::::::::::::::::::~:~::::rI::::~::~:::~::::::~e~:::~R~~::::/~::::::::::~:i:::::::::::::~:::u:::~)::;:
Colorado Hazardous Waste Act
6 CCR 1007-3 Part 260-261 Defines those solid wastes subject to
Identification and Listing of hazardous waste regulations.
Hazardous Waste
6 CCR 1007-3 Part 262
Standards Applicable to
Generators of Hazardous
Waste
6 CCR 1007-3 Part 264
Subparts B, C, and D
Standards for Owners and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
6 CCR 1007-3 Part 264
Subpart F
DENIOOIS382.WPS
Establishes staDdards for RCRA
generators.
Establishes minimum staDdards that
define the acceptable management of
hazardous waste for owners and
operators of facilities which treat,
store, or dispose of hazardous waste.
Sets ground-water protection standards
for land disposal units.
8-55
':-:':':':"',':';';',.
....
.:.:.:.:.:.;.:.:.:.:.;,:.:.:
.....
.....
:-:-:':':':':',
......
The State of Colorado has an approved delegated program
for this portion of RCRA. Applicable to determining
whether subslanCes are hazardous wastes under RCRA.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment plant residuals and waste generated during
construction of the barrier walls. Therefore, waste
generated must meet these standards which include testing
per 40 CFR. Part 261, temporary tanks or containers,
inspection and leak detection, offsite shipping procedures,
and accumu1ation time. The State of Colorado has an
approved, delegated program under RCRA.
Because remediation activities constitute treatment and
storage activities (ground-water treatment plant and residuals
management), and because the water to be treated is
sufficiently similar to RCRA hazardous waste such that use
of the requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment component of the remedy (mcluding residuals
management). Thus, treatment of the ground water must
meet these staDdards, which include waste analysis, site
security, emergency control and response equipment,
personnel training, contingency planning and
implementation.
The State of Colorado operates an approved delegated
program for this portion of RCRA. See the requirements
under Part 264.94 of the Colorado Hazardous Waste Act.
Relevant and appropriate to ground water under the site
because the landfill operates like a solid Waste management
unit. Therefore, ground-water programs must meet these
standards, which include a monitoring and response
program that includes detection monitoring to identify the
presence of hazardous constituents in ground water;
compliance monitoring to determine whether the agency-
specified ground-water protection standard is being met at
the identified compliance point; and corrective action that
prevents hazardous constituents from exceeding the
established concentration limits beyond the point of
compliance.
-------
Citation
...
.....
.....
. . ... . ..:..:/:~:~:~:~~~:~:r::::~? ... . . .. . ...
......
6 CCR 1007-3 Part 264
Subpart G
6 CCR 1007-3 Part 264
Subpart I
6 CCR 1007-3 Part 264
Subpart J
6 CCR 1007-3 Part 265.17
DEN10015382.WP5
I
Table 8-1
ARARs for OUs 1&6
Page 7 o~
Description
..::!!!!!=:!::!!:!~~~~::~'::'::$i;f~:)~~~j!!=}:::::!=j==!!:!:=:j:=j=:!::::!=::::!j::!!::!'!!I:!!:?!:!::::'::!:!!:!!!:::!!':!::i:!:i:,I?i:::::::!'::!:=:::
Because ground-water treatment constitutes treatment of a
waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is well suited to the
situation, the requirement is relevant and appropriate to the
ground-water treatment component of the remedy.
Therefore, closure and post-closure care for these treatment
system must meet these standards which include removal of
waste, waste residues, contaminated system components,
and contaminated subsoils; or closure with wastes and/or
contamination in place with containment systems and post-
closure care to include ground-water monitoring and
inspection and mainteD8IICe on containments and monitoring
systems.
Because ground-water treatment includes storage in
containers of a waste that is sufficiently similar to RCRA
hazardous waste such that use of the requirement is weD
suited to the situation, the requirement is relevant and
appropriate to the ground-water treatment component of the
remedy. Therefore, container storage at the ground-water
treatment plant must meet these standards, which include
maintaining Wastes in containers that are in good condition
and compatible with the wastes they contain, providing a
containment system, managing ignitable and reactive wastes
away from the property line, keeping incompatible wastes in
separate containers and containment systems, and at closure
removing all wastes and decontaminating structures and
equipment.
Because ground-water treatment includes storage in tanks of
a waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is well suited to the
situation, the requirement is relevant and appropriate to the
ground-water treatment component of the remedy.
Therefore, tank storage at the ground-water treatment plant
must meet these standards, which include secondary
containment, spill and overflow controls, removal from
service if there is a leak, spill, or the tank is unfit for use,
and at closure have all wastes removed and also remove or
decontaminate waste residues, containment system, soils,
structures, and equipment.
Because the ground-water treatment plant will mix and treat
potentially incompatible, reactive, or ignitable wastes which
may be similar to hazardous wastes, the requirement is
relevant and appropriate to the ground-water treatment
plant. Therefore, the wastes must be analyzed to determine
compatibility, reactivity, and ignitability before treatment in
the treatment plant.
...
Closure and post-closure care.
Sets operating and performance
standards for container storage of
hazardous waste.
Sets operating and performance
standards for tank storage of hazardous
waste.
Sets standards for mixing and treatment
of contaminated soils or the mixing and
treatment of potentially incompatible,
reactive, or ignitable hazardous wastes.
Evaluation
8-56
-------
Table 8-1
ARARs for OUs 1&6 Page 8 of8
Citation Description Evaluation
6 CCR. 1007-3 Part 268 Establishes prohibitions on land Because the constnlction residuals from the ground-water
Land Disposal Restrictions disposal unless treatment standards are barrier walls will be land disposed, the requirement is
met or a "DO migration exemption" is applicable. The materials must be tested to determine if
granted. they arc a characteristic hazardous waste (per 6 CCR. 1007-
3 Part 262) and then must meet treatment requirements for
land disposal as required in the standards if they are
hazardous waste for which a treatment standard has been
established. For land disposal of residuals, other than soils,
which are DOt characteristic hazardous wastes, these
requirements are relevant and appropriate because the
residuals are sufficiently similar to listed hazardous waste
such that use of the requirements is well suited to the
situation.
Colorado Air Quality Ad] Air Pollution Regu1atioDS
5 CCR. 1001-5 Requires filing of Air Pollution These regulations are applicable because air emissions will
Regulation No.3 Emission Notice (APEN) including occur at the treatment plant. The air stripper/carbon
estimation of emission rates. polishing treatment process must meet any substantive
provisions of these requirements.
5 CCR. 1001-8 Establishes standards for new stationary These regulations are applicable because air emissions will
Regulation No.6 sources including incinerators. Sets occur at the treatment plant. The air stripper/carbon
discharge and performance rates and polishing treatment process must meet these requirements
opacity requirements. which include discharge and performance rates and opacity
requirements.
5 CCR. 1001-9 Establishes standards for disposal or These regulations are applicable because air emissions will
Section n.C.2, Section V spillage ofVOCs. occur at the treatment plant. The air stripper/carbon
Regulation No.7 polishing treatment process must meet these requirements
which include controls representing reasonably available
control technology (RAC'I).
Colorado Noise Abatement Statute
Colorado Revised Statute Provides limits for noise based on time Applicable for all construction activities associated with the
Section 25-12-103 periods and ZODCS. remedy.
Water WeD Pump InstaBatioa Coatractors Ad
2 CCR. 402-4 Establishes standards for installation of Applicable because wells will be installed.
water wells and pumping equipment.
Well ConstructioniAbaadomnent Requinmeots
2 CCR. 402-2 Well construction/abandonment Applicable for new wells and abandonment of existing
State of Colorado Division requirements weDs. Additional requirements may be added to ensure that
of Water Resources, 1988, a migration pathway is DOt created.
as revised-Colorado State
Engineers Office
!!!!!!::!:!i!::i!i!::'!!!!!!!!!i:i!{(i'!!:::j'!@::@i!:jj!!:::':::::t:j'!i!:!!!:!:!!::!j!!'!!:!:j:!:jjj!!!::!j!::@:::::!:!!'!!j!:::~~!j:~e~~~~i:;tll:j!:j!:::j:!:!:j:::':'!!:!!!:!!t!!j::!,::::!:::i::::j':::::::!'!::!!'!:!:!:jjjj:!!!!j!!::'::j::!;i::'j':!!::!::'!!:::!!!:!:j:::::!:::(:
Federal Water Pollution Control Ad (Clean Water Act)
40 CFR Part 230 Discharge of dredged or till material For areas of the site that have designated wetlands, a permit
into wetlands prohibited without a will not be required pursuant to Section 121(c) of
permit. CERCLA, but the substantive requirements of Part 230 will
be applicable if wetlands that have been identified at the
Lowry Site are dredged or tilled during implementation of
the remedial activity.
Certifiaation of Federal Licenses and Permits
5 CCR. 1002-18 Discharge of dredge and till material For areas of the site that have designated wetlands, a permit
into wetlands prohibited without a State will not be required pursuant to Section 121 (c) of
certification. CERCLA, but the substantive requirements will be
applicable if wetlands that have been identified at the Lowry
Site are dredged or tilled during implementation of the
remedial activity.
DEN10015382.WPS
8-57
-------
CitatioD.
",':':.'
',"';',
:.:::::,:;:.::::.;.::::
:-..:-.,:.:.',",','.'.:
;':':';';',',',',','"
P"
.....
....
... ..
.. .
. .
5 CCR 1001-3
Regulation No.1
5 CCR 10014
Regulation No.2
5 CCR 1001-10
Regulation No.8
40 CFR. Part 241
Guidelines for the Land
Disposal of Solid Wastes
40 CFR Part 257
Criteria for Classification of
Solid Waste Disposal Facili-
ties & Practices
[)~10015386.VVP5
Table 8-2
ARARs for OUs 2&3
Page 1 017
Evaluation
Description
"""':",,:::!:!:::':!":::::~~S~!~!i~:':::~~fi!!!i!:!::!!!!!'ii!::::i:!::!:!i'i'i':::i:::':::ii:i:i:!:!!::,:!!:!::!':::/::::!:;:':::!:::!i:i::!iii':::['::!i': [;::!:::::J:::::!:'i:j:!::!::::!
Colorado Air Quality AdJ Air PoDution Regulations
Establishes standards for emissions of These regulations are applicable because air emissions will
particulates, smoke, caroon monoxide, occur at the gas treatment system and due to COnstruction
and sulfur oxides. activities. These regulations would be met for the gas
Oaring system and during construction. Regulations for
opacity and offsite transport of visible fugitive emissions are
applicable and must be attained during construction activi-
ties resulting in disturbance of 5 acres or more in attainment
areas or one acre in nonattainment areas. The LoWl)' Site is
in an attainment area for sulfur oxides and lead and in a
nonaUainmentarea for PM 10, ozone, and caroon
monoxide.
These regulations are applicable because air emissions will
occur at the site during all activities. Activities regulated
include activities such as soil movement. These regulations
would be met for all activities including the excavation of
soil in the former tire pile area, and movement of soil for
construction of the gas coUection and treatment system.
These regulations are applicable because air emissions will
occur at the gas treatment system. These regulations would
be met for the gas flare. The lead standards are applicable
because they are ambient standards that apply to all sources.
The beryllium provisions set out emission limitations for
stationary sources that are applicable for all sources. The
hydrogen sulfide standards are applicable to any actions
emitting hydrogen sulfide. The mercury standards are
applicable if wastewater treatment plant sludge is dried or
incinerated.
. .
n..
:::i:::J!/:':::!::/:}:!:::,!:(i::':"=:(:,i':':fJ:!::i::::!:f[i':i:::::::::::::i:!:::::':![:i:::::~@~~:::~*!~!:':}?!=if"!:!""'!::}'):!:'ii!!:U:;::::::m:![:i}!!:::'::t:i'j!!!::j:::i::'!::,i!:::::!:f'::ii'!!//!i:!:::::
Solid Waste ~ Ad-RCRA Subtitle D Requiremeats
Establishes minimum levels of perfor- Because the Lowry Site is a landfiU and because decomposi-
mance required of any solid waste land tion gases have been detected, this requirement is weU
disposal site operation. suited to the situation and is relevant and appropriate to the
Part 241.20S-2(b) states "decomposi- gas coUection and treatment system. Therefore, the gas
tion gases should not be allowed to coUection and treatment must meet these standards, which
concentrate in a manner that will pose include maintaining methane below explosive limits.
an explosion or toxicity hazard. .
Establishes criteria for use in determin-
ing wbich solid waste disposal facilities
and practices pose a reasonable proba-
bility of adverse effects on health or
the environment and thereby constitute
prohibited open dumps.
Sets limits on odorous air contaminants
and particu1ates.
Sets emission control requirements for
hazardous air poUutants.
8-58
Applicable for existing MSW landtills. The Section 6
MSW landtill is a closed landtil1. Landtill cover
requirements are relevant and appropriate.
-------
Page 2 of71
Table 8-2
ARARs for OUs 2&3
Description EvaluatioD
i::!:::::::::::;:;!:!!:::;:::r:::::r::;!::::::::::::::\....... .....:....::...:.:.:r.::::~~.::~~~::~:eF~~:~~~~::...".. . .. .... ....................
,... ..''', . ",.,.......
Establishes design and operational Explosive gas requirements (part 258.23) are relevant and
criteria for all new municipal solid appropriate since waste was not received after October 9,
waste landfills or expansions of exist- 1993, but the use of the requirement is well suited to the
ing facilities. The requirements vary situation. Therefore, methane monitoring within onsite
depending on the time frame that the structures and at the facility property boundary is required.
land disposal unit is used. Includes Landfill cover requirements are relevant and appropriate
closure and post closure care. since waste was not received after October 9, 1991, but the
. If the landfill slopped receiving use of the requirement is well suited to the situation.
waste prior to 10/9/91 it is not Therefore, landfill cover maintenance is required.
regulated
. If the landfill slopped receiving
waste prior to 10/9/93 the facility
must comply with tina1 cover
requirements
. If the landfill receives waste on or
after 10/9/93 the facility must
comply with all requirements of
40 CFR 258
Solid Waste Disposal Act-RCRA Subtitle C Regnlations
Defines those solid wastes that are The State of Colorado has an approved delegated program
subject to regulation as hazardous for this portion ofRCRA. The regulations are applicable
wastes under 40 CFR Parts 262-265 for purposes of determining whether any of the materials
and Parts 124, 270,271. being treated or disposed are hazardous wastes. Materials
may also be compared to the waste listings to determine
whether any of the materials are sufficiently similar such
that RCRA regulations are relevant and appropriate.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requirement is well suited to the situation, the
requirement is relevant and appropriate to solids excavated
from the former tire pile area, gas that is collected and
treated, and waste generated during construction activities
for the gas extraction system. Therefore, waste generated
must meet these standards which include testing per 40 CFR
Part 261, temporary tanks or containers, inspection and leak
detection, and accumulation time. The State of Colorado
has an approved, delegated program under RCRA.
Because remediation activities constitute treatment and
storage activities (gas treatment and residuals management),
and because the gas to be treated is sufficiently similar to
RCRA hazardous waste such that use of the requirement is
well suited to the situation, the requirement is relevant and
appropriate to the gas treatment component of the remedy
(mcluding residuals management). Thus, flaring of the gas
must meet these standards, which include waste analysis,
site security, emergency control and response equipment,
personnel training, contingency planning and
implementation.
Citation
40 CFR Part 258
Regulations Concerning
Municipal Solid Waste
Landfills
40 CFR Part 260-261
Identification and Listing of
Hazardous Waste
40 CFR Part 262
Standards Applicable to
Generators of Hazardous
Waste
Establishes standards for RCRA
generators.
40 CFR Part 264 Subparts
B, C, and D
Standards for Owners and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
Establishes minimum standards that
define the acceptable management of
hazardous waste for owners and opera-
tors of facilities which treat, store, or
dispose of hazardous waste.
8-59
I>El\IlOOI5386.VVPS
-------
Citation
Table 8-2
ARARs for OUs 2&3
Page 3 Of~
40 CFR Part 264 Subpart G Closure and post-<:losure care.
.
Desuiptioa Evaluation
"'::\ffii:) (j"::;:':{":::,:.,';:,::,:::;::;:::,:, :,},:,::;:,;:{:~,':~,:~:,:, :::\;::::~::~7f~";;'~~::;::;jj;.';:j:::;;:::.;.:;:.';"j::;;;r;;:;;;;;;;::;::;':;:;i;:;:::;:;,;::';:;;;:;;J;:;;;:::;;;;;;!:;:;';::'::':Il;
:r::i:;;r~;::;::::::::.. . .. .
Because gas treatment constitutes treatment of a waste that
is sufficiently similar to RCRA hazardous waste such that
use of the requirement is well suited to the situation, the
requirement is relevant and appropriate to the gas treatment
components of the remedy. Therefore, closure and post-
closure care for this treatment system must meet these
standards which include removal of waste, waste residues,
contaminated system components, and contaminated sub-
soils; or closure with wastes and/or contamination in place
with containment systems and post-<:losure care to include
ground-water monitoring and inspection and maintenance on
containments and monitoring systems.
Because gas treatment constitutes thenna! treatment, and
because the gas to be treated is sufficiently similar to RCRA
hazardous waste such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the gas flaring component of the remedy.
Thus, flaring of the gas must meet these standards, which
include emissions standards and operating constraints as
needed to ensure emissions standards are met.
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar to RCRA hazardous waste such that the use of the
requirement is well suited to the situation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include standards for process vents
and test methods and procedures.
Because gas flaring constitutes thermal treatment and
because the gas to be treated is sufficiently similar to RCRA
hazardous waste such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the gas treatment component of the remedy.
Therefore, the gas treatment system must meet these stan-
dards, which include general operating requirements, waste
analysis, monitoring and inspection, and closure.
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar to RCRA hazardous waste such that the use of the
requirement is well suited to the situation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include standards for process vents
and test methods and procedures.
40 CFR Part 264 Subpart 0
40 CFR Part 264
Subpart AA
40 CFR 26S Subpart P
Interim Standards for
Owners and Operators of
Hazardous Waste
Treatment, Storage, and
Disposal Facilities
40 CFR Part 26S Subpart
AA
DEN 1 OOlS386.WPS
Sets standards for destruction and
removal efficiency, HCl emissions, and
particulate emissions from incinerators
or thermal treatment.
Sets operation and performance stan-
dards for air emissions from process
vents.
Standards for thermal treatment.
Sets operating and performance stan-
dards for air emissions from process
vents.
8-60
-------
Citation
Table S-2
ARABs for OUs 2&3
page40f71
...
Establishes a concentration limit for
over 200 regulated constituents in soil,
regardless of waste type, which must
be met before land disposal.
Federal Water PoBution CoutroI Ad (ameoded by the Clean Water Ad)
Establishes requirements for storm- Because stormwater discharges will occur from the landfill
water discharges related to industrial and from any treatment process areas collSlrUcted (such as
activity. Stormwater runoff, snow melt the gas treatment system), this requirement is applicable to
runoff, and surface runoff and drainage stormwater discharges. Therefore, stormwater discharges
associated with industrial activity from must meet these standards which include sampling, analysis,
remedial actions which discharge to and treatment requirements. Implementation and enforce-
surface waters shall be conducted in ment has been delegated to the State of Colorado, see the
comp\iancewith RCRA, FWQC, CWA Colorado Water Quality Control Act.
technology-based standards, Colorado
surface water quality standards, moni-
toring requirements, and best manage-
ment practices.
Description Evaluation
::::::::r:::::f::::::::::::::::f::::::::r::::::::::::::::'j::::::f::,:,.:.:.::.:i.':.::.:.':.::.::.:.::::':t:;;::i~~~:::~:$!~~J4~g:::::J::::::::::::::::':::::::,):::::::::::.. ......:... ....
. . . . . . . . . . . .. ................ ........" .. . .
40 CFR. Part 268 Establishes prohibitions on land dis- Because the solids excavation in the former tire pile area
Land Disposal Restrictions posal unless treatment standards are and residuals from the gas extraction system collSlrUction
met or a "no migration exemption" is and residuals from the gas extraction system operations will
granted. be land disposed, the requirement is applicable. The mate-
rials must be tested to determine if they are a characteristic
hazardous waste (per 40 CFR. Part 262) and then must meet
treatment requirements for land disposal as required in the
standards if they are hazardous waste for which a treatment
standard has been established. For land disposal of
residuals, other than soils, which are not characteristic
hazardous wastes, these requirements are relevant and
appropriate because the residuals are sufficiently similar to
1isted hazardous waste such that use of the requirements is
well suited 10 the situation.
TBC for soil and sediments because it is a proposed regula-
tion. Excavated soils from the tire pile area must meet
these requirements.
58 FR. 48091 (9/14/93)
40 CFR. Part 268
Universal Treatment
Standards
40 CFR Part 122
NPDES Stormwater
Regulations
40 CFR Part 60
New Source Performance
Standards
40 CFR. Part 61
National Emission
Standards for Hazardous
Air Pollutants (NESHAPs)
Clean Air Ad
Establishes performance standards for
new stationary sources of air pollut-
ants.
Establishes emission standards for
hazardous air pollutants from specific
sources.
Relevant and appropriate for gas treatment. Proposed NSPS
for municipal solid waste facilities (Subpart WWW) is a
TBC (56 FR. 24468 [5130/9ID.
Because the gas treatment system will have a flare, this
source is sufficiently similar to source types in the regula-
tions such that use of the requirement is well suited 10 the
situation, the requirement is relevant and appropriate to the
gas treatment system. Therefore, the gas flare must meet
these standards which include treatment levels for arsenic,
beryllium, benzene, vinyl chloride and radionuclide
emissions.
:?:ji':"::j::'::'::::::':::::::i::;:;::j::::::::)::::',::i?'?i:::::';:::::::::::::j::@:,;:j::;t::'f:,:::::::f:::f:':.:::'::::::~$,@~:~*~;:::,::::::::::j::j::::::::f:::::::::::::::i:::i':.;j:::j::::::;::'U::::ji::::::::::,:::U:::
Colorado Solid Wastes ~posaI Sites and Facilities Ad
6 CCR 1007-2 Section 1
Regulations Pertaining to
Solids Waste Disposal Sites
and Facilities
DENlOO15386.WPS
Establishes standards for new solid
waste disposal facilities and defines
those solid wastes.
8-61
.... ......' .....
..."........ ..
;.:-:.:-:.::.;.;.:.:.;.:.:.:.:.:.;
........".......
... """'"''
Explosive gas requirements and landtill cover requirements
are relevant and appropriate because waste was not received
after October 9, 1993, but the use of the requirement is well
suited to the situation so the requirement is relevant and
appropriate 10 the existing landfill mass. Therefore, the gas
concentrations need 10 be maintained below the explosive
limits and maintenance of the landfill cover is required.
-------
Page S or~
Table 8-2
ARARs for OUs 2&3
Evaluation
Description
{::",,:\//::::!:'::,;:::!:::::n::\:::::::::,,:,:;;:::::::/:::::::~~~:::_:::::'::$t.~::::~i::::::::::!!;:!::iI!';:::::I;:::':::;':::n::;::':':::;';::::::::"::;::::':;:::::::::::;:::!!!'::::;:':::'::::::!!:':::}::'::
.. .... ... .........
6 CCR 1007-2 Section 2.3 Establishes minimum standards for These requirements are applicable for the landfill gas col-
landfill gas collection and treatment lection and treatmeDt system and include monitoring
systems. ~uirements in structures and at the landfill boundary,
notification of gas excursions, and remediation activities if
explosive gas limits are exceeded.
Substantive requirements are applicable to the gas extraction
system and landfill cover. Requirements include maintain-
ing the cover for 30 years, ground-water monitoring,
descnlling uses of land during post closure care, and certifi-
cation at the completion of post closure care.
Colorado HazardODS Waste Act
Defines those solid wastes subject to The State of Colorado has an approved delegated program
hazardous waste regulations. for this portion of RCRA. Applicable to determining whe-
ther substances are hazardous wastes under RCRA.
Citation
Post closure maintenance and care.
6 CCR 1007-2 Sections 2.6
and 3.6
6 CCR 1007-3 Part 260-261
Identification and Listing of
Hazardous Waste
6 CCR 1007-3 Part 262
Standards Applicable to
Generators of Hazardous
Waste
Establishes standards for RCRA
generators.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requiremeDt is well suited to the situation, the
~uiremeDt is relevaDt and appropriate to the solids exca-
vated from the former tire pile area, gas that is treated, and
waste generated during construction of the gas extraction
system. Therefore, waste generated must meet these
standards which include testing per 40 CFR. Part 261, tem-
porary tanks or containers, inspection and leak detection,
offsite shipping procedures, and accumulation time. The
State of Colorado has an approved, delegated program
under RCRA.
Because remediation activities constitute treatment and
storage activities (gas treatment and residuals management),
and because the gas to be treated is sufficiently similar to
RCRA hazardous waste such that use of the requirement is
well suited to the situation, the requiremeDt is relevant and
appropriate to the gas treatment components of the remedy
(mcluding residuals managemeDt). Thus, flaring of the gas
must meet these standards, which include waste analysis,
site security, emergency coDtroI and response equipment,
personnel training, coDtingency planning and
implementation.
Because gas treatment constitutes treatmeDt of a waste that
is sufficiently similar to RCRA hazardous waste such that
use of the requirement is well suited to the situation, the
~uirement is relevaDt and appropriate to the gas treatment
components of the remedy. Therefore, closure and post-
closure care for this treatment system must meet these
standards which include removal of waste, waste residues,
contaminated system components, and contaminated sub-
soils; or closure with wastes and/or contamination in place
with contammeDt systems and post-closure care to include
ground-water monitoring and inspection and maintenance on
containments and monitoring systems.
6 CCR 1007-3 Part 264
Subparts S, C, and D
Standards for Owntrs and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
Establishes minimum standards that
define the acceptable management of
hazardous waste for owners and opera-
tors of facilities which treat, store, or
dispose of hazardous waste.
6 CCR 1007-3 Part 264
Subpart G
Closure and post-closure care.
I>~IOOI5386.VVP5
8-62
-------
Table S-2
ARARs for OUs 2&3
Page 6 of 7
Evaluation
Citation Descriptioo
:,:::~'~:i:'~::i:ii~~:'::::ii::~~:::i~~~:'::::::'::~~:::',::~::::::::::/:::::::::::::::::::::::;~::t:'i:~:::::::::::i:::::::::::.~~Ki:::~R~~~:(~Mi::'::::::,::::::U::::::::::{\::,:::))):::............. .. ........
6 CCR 1007-3 Part 264 Sets standards for destruction and Because gas treatment constibJtes thermal treatment, and
Subpart 0 removal efficiency, Bel emissions and because the gas to be treated is sufficiently similar to RCRA
SlaDdards for Owners and particulate matter in excess of the hazardous waste such that use of the requirement is well
OperalOrs of Hazardous stated standard. suited 10 the situation, the requirement is relevant and
Waste TSD Facilities appropriate to the gas flaring component of the remedy.
Thus, flaring of the gas must meet these standards, which
include standards for process vents and test methods and
procedures.
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar 10 RCRA hazardous waste such that the use of the
requirement is well suited 10 the sibJation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include general operating require-
ments, waste analysis, monilOring and inspections, and
closure.
Because gas flaring constibJtes thermal treatment and
because the gas to be treated is sufficiently similar 10 RCRA
hazardous waste such that use of the requirement is well
suited 10 the situation, the requirement is relevant and
appropriate to the gas treatment component of the remedy.
Therefore, the gas treatment system must meet these sIaD-
dards, which include standards for process vents and test
methods and procedures.
Because the gas treatment has process vents from thermal
treatment and because the gas 10 be treated is sufficiently
similar 10 RCRA hazardous waste such that the use of the
requirement is well suited 10 the situation, the requirement
is relevant and appropriate 10 the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include general operating require-
ments, waste analysis, monilOring and inspections, and
closure.
6 CCR 1007-3 Part 264
Subpart AA
Sets operating and performance sIaD-
dards for air emissions from process
vents.
6 CCR 1007-3 Part 265
Subpart P
Standards for thermal treatment.
6 CCR 1007-3 Part 265
Subpart AA
Sets operation and performance stan-
dards for air emissions from process
vents.
6 CCR 1007-3 Part 268
Land Disposal Restrictions
Establishes prohibitions on land dis-
posal unless treatment standards are
met or a "DO migration exemption" is
granted.
Because the solids excavation in the former tire pile area
and constnlction residuals from the ground-water barrier
walls and gas extraction system will be land disposed, the
requirement is applicable. The materials must be tested 10
determine if they are a characteristic hazardous Waste (per 6
CCR 1007-3 Part 262) and then must meet treatment
requirements for land disposal as required in the standards if
they are hazardous waste for which a treatment standard has
been established. For land disposal of residuals, other than
soils, which are not characteristic hazardous wastes, these
requirements are relevant and appropriate because the
residuals are sufficiently similar 10 listed hazardous waste
such that use of the requirements is well suited 10 the
situation.
Colorado Air Quality As:tJ Air PoDution ReguJatioas
Requires tiling of Air Pollution Emis- These regulations are applicable because air emissions will
sion Notice (APEN) including estima- occur at the gas treatment system. The gas flaring process
tion of emission rates. must meet any substantive provisions of these requirements.
Establishes slaDdards for new stationary These regulations are applicable because air emissions will
sources including incineralOrs. Sets occur at the gas treatment system. The gas flaring process
discharge and performance rates and must meet these requirements which include discharge and
opacity requirements. performance rates and opacity requirements.
5 CCR 1001-5
Regulation No.3
5 CCR 1001-8
kegulation No.6
8-63
DEN 1 001 S386.WP5
-------
Citation
p"
. ...
. ......
'"
5 CCR 1001-9
Section D.C.2, Section V
Regulation No.7
Colorado Revised Statute
Section 25-12-103
2 CCR 402-4
2 CCR 402-2
State of Colorado Division
of Water Resources, 1988,
as revised -Colorado State
Engineers Office
Page 7 Of~
.......
Table 8-2
ARARs for OUs 2&:3
Description Evaluation
,:':"%:~~~~"~7'$t~?(~~~~):':;,;;:;::!:;::!:8:;':;:':;:;:":;;:;:i::(::;;:j[[[I
These regulations are applicable because air emissions will
occur at the gas treatment system. The gas f1ariug process
must meet these requirements which include controls repre-
senting reasonably available control technology (RAC'I).
Colorado Noise Abatemeat Statute
Provides limits for noise based on time Applicable for all construction activities associated with the
periods and zones. remedy.
Water Well Pump JustAnAfinQ Contractors Act
Establishes standards for installation of Applicable because weDs will be installed.
water weDs and pumping equipment.
Well ComtructiooI AbaDdoDDIeat Requiremeots
WeD construction/abandonment Applicable for new weDs and abandonment of existing
requirements weDs. Additional requirements may be added to ensure that
a migration pathway is not created.
Establishes standards for disposal or
spillage of VOCs.
t~~ijjtf~~I~j~j~~r:rtr~:~;:i:~:~:::::~:~(\ft:{j(1~~~~;f~if~tt~tj\:~:/~~~~;;i~~~~~[~j~~~~#~i;~2F~4~~!~;ij;:!~~~:~;i i/t~~~:~:~:\:::~.;~~~:~~:~~:: ...."'" '~::~:j~~t;~:::::;:f{\i~:t~ti}i~)i:[:~
Federal Water Pollutioa Control Ad (Clean Water Ad)
Discharge of dredged or till material For areas of the site that have designated wetlands, a permit
into wetlands prohibited without a will DOt be required pursuant to Section 121 (c) of
permit. CERCLA, but the substantive requirements of Part 230 will
be applicable if wetlands that have been identified at the
Lowry Site are dredged or tilled during implementation of
the remedial activity.
",i,iii, ,,:: ::""",',',,::',',"::::::,:,':::::: "'" "'" 'iiiii"" ,:::::;:~~~~$~~':~;2$~~::;::j::;j;::;::::;,;!::::::;::::;::::j:::::;t::::::::::::::::j:j);:;::::::::;::::;i;;j::;i:i;::;::i:::::II
Certification or Federal Liceoses aad Permits
Discharge of dredge and till material For areas of the site that have designated wetlands, a permit
into wetlands prohibited without a State will not be required pursuant to Section 121 (c) of
certification. CERCLA, but the substantive requirements will be applica-
ble if wetlands that have been identified at the Lowry Site
are dredged or filled during implementation of the remedial
-------
Table 8-3
ARARs for OVs 4&5
Citation Description
:;:;;:;;::;;::;;:;;:'r::::::;{::::::::::!:,:::::::::::::::,::::::':':::::'::::'::::::j::::::)::::::::::::j:::!:::::::::~~~~'~#~~~~~~.);:: .:)::::...........
Safe DriDkiDg Water Art
Establishes health-based standards for These regulations are relevant and appropriate because the
public d~ water systems (MCLs). shallow aDd deep ground water in the vicinity of the Lowry
Site is being used or may be used in the future as a source
of water for a public water system or private supply wells.
Treated ground water from the treatment plant would be
~ected into the shallow ground-water system. The
standards are pertinent to treatment plant effluent at the
point of injection as well as within the ground water at the
compliance boundary.
Establishes drinking water quality goals Non-zero MCLGs are relevant and appropriate since shal-
set at levels of no known or anticipated low and deep ground water in the vicinity of the Lowry Site
adverse health effects, with an adequate is being used or may be used as a source of water for a
margin of safety (MCLGs). public water system or private supply wells.
Federal Water PoDution CoDtroI Art (ameoded by the Clean Water Art)
Establishes toxic pollutant effluent Relevant aDd appropriate for treatment plant effluent
standards for six groups of toxic pollut- because compound groups were detected in waste pit liquids
ants from manufac1Urers, formulators, aDd unnamed creek and Murphy Creek discharges to the
and applicators who develop or use South Platte River, which is a navigable water.
these compounds and discharge to
navigable waters.
:::::::::::::::::::::...... .......:.:.):::::::::::::::::::';::j:i::i::::::)"::"'::'H~~~~~:~+~t¥./
Colorado Hazardous Waste Art
40 CFR Part 141
Subpart B
40 CFR Part 141
Subpart F
40 CFR Part 129
Toxic Pollutant Effluent
Standards
6 CCR 1007-3 Part 264.94
Colorado Rules and
Regulations Pertaining to
Hazardous Waste-Ground
Water Protection Standard
5 CCR 1002-3
Regulation on Effluent
Limitation
5 CCR 1003-1
Colorado Primary Drinking
Water Regulations
5 CCR 1002-8
Section 3.11.0
Colorado Basic Standards
for Ground Water
aDd Section 3.12.0 Classifi-
cations aDd Water Quality
Standards for Ground Water
DEN10015389.WP5
Establishes concentration levels for 14
chemicals in ground water.
Page 1 of8
Evaluation
....
',,',','
..
.....
. .
. .
... ..
..
....
.....
...
The concentration limits are relevant and appropriate to
treatment plant effluent.
Colorado Water Quality Control Art
Establishes specific limitations on point
source discharges of wastewaters into
state waters aDd from specified industry
sources, specifies sampling aDd analyti-
cal requirements.
Establishes health-based standards for
public water systems.
Establishes a syslem for classifying
ground water aDd sets water quality
standards for such c1assifications.
Relevant and appropriate for discharge from treatment plant.
These regulations are relevant aDd appropriate because the
shallow aDd deep ground water in the vicinity of the Lowry
Site is being used or may be used in the future as a source
of water for a public water system or private supply wells.
Treated ground water from the treatment plant would be
injected into the shallow ground-water system.
These regulations establish standards for both classified and
unclassified ground water. The standards are applicable
because ground water (within non-alluvial and alluvial
aquifers) near the Lowry Site and ground water (within
alluvial aquifers) within the Lowry Site have been classified
for domestic and agricultural use-quality. Ground water
would be treated to meet these standards and then
discharged to the shallow ground-water system.
8-65
-------
Citation
:~::;~~ft~~??f?fIfI~tt!!t!~~~~~r!{:
. .
5 CCR 1002-8
Section 3.1.0
Basic Standards and
~e~odol~esforSunBce
Water
5 CCR 1002-8
Section 3.2.0
Classifications and Numeric
Standards
5 CCR 1001-3
Regulation No. I
5 CCR 1001-4
Regulation No.2
5 CCR 1001-10
Regulation No.8
5 CCR 1001-14
Ambient Standards
DENlOOI5389.WP5
Table 8-3
ARARs for OUs 4&S
Page 2 ors
DescripDOD Evaluation
\(i::::::~:::f::::).:.::::::::~~~..{:~~:~~:!!~~~~;'@j:!!:::::~::~~:::~~i:::::::ft::::~:~:::::::::::~:::::~:::!~::::::::~!t!:~:::!!!:t!!:::!t::!:::j:::::~::::::::~!:::~~d;j
... ,
Establishes basic standards and a ~urphy Creek and the wmamed creek are classified and
system for classifying surface waters of regulated as tributaries of the South Platte River Basin
the State, assigning standards, and (Stream Segment 16). Segment 16 is classified as Recre-
granting temporary variances for the ation Class 2, Warm Water Aquatic Life Class 2, and Agri-
standard. cultural Supply. Beuuse of this classification, statewide
interim organic ponutant standards for aquatic life segmeDls
(Section 3.1.11 and Table C) are applicable to the remedy.
If surface-water discharge results from injection of ~e
treated water, surface water standards will be established
based on ~e most stringent surface water ARAR.
~urphy Creek and the wmamed creek are classified and
regulated as tn"butaries of the South Platte River Basin
(Stream Segment 16). Segment 16 is classified as Recre-
ation Class 2, Warm Water Aquatic Life Class 2, and Agri-
cultural Supply. Based on the regulations, numeric stan-
dards for proleCtion of these three classified uses are appli-
cable. Cbemical-specific standards established for Stream
Segment 16 are applicable to the remedy. If sunBce-water
discharge results from injection of the treated water, surface
water standards will be established based on the most SIrin-
gent surface water ARAR.
Colorado Air Quality .Ad} Air PoDutiOD Regulations
Establishes standards for emissioDS of These regulatiODS are applicable because air emissions will
particulates, smoke, carbon monoxide, occur at the grouad-watertreatment plant. These regula-
and sulfur oxides. tiODS would be met for the air stripper/carboD polishing
treatment process. RegulatioDS for opacity and offsite trans-
port of vist"ble fugitive emissioDS are applicable and must be
attained duriog construction activities resuJtiag in dislur-
bauce of 5 acres or more in attainment areas or one acre in
noaattamment areas. The Lowry Site is in an attainment
area for sulfur oxides and lead and in a noaattaiament area
for PM 10, ozone, and carbon monoxide.
Sets limits on odorous air CODtamiDaots These regulatioDS are applicable because air emissions will
and particulates. occur at the site during all activities. Activities regulaled
include activities such as treatment plant air emissions.
These regulatiODS would be met for all activities iDcluding
the air stripper/carbon polishing treatment process.
Sets emission control requirements for These regulatioDS are applicable because air emissions occur
hazardous air ponutants. at the treatment plant. These regulations would be met for
the air stripper/carbon polishing treatment process. The
lead standards are applicable because they are ambient
standards that apply to all sources. The beryllium provi-
sioDS set out emission limitatiODS for stationary sources that
are applicable for all sources. The hydrogen sulfide stan-
dards are applicable to any actioDS emiuiag hydrogen sul-
fide. The mercury standards are applicable if wastewater
treatment plant sludge is dried or incinerated.
Establishes ambient standards for S~, These regulatioDS are applicable because air emissioDS occur
TSP, N~ CO, ozone, and PM 10. at the treatment plant. These regulations would be met
because these parameters are not expected to be present. If
these parameters are detected above the regu1aled levels,
action will be taken to correct the problem.
Used in conjunction with Basic Stan-
dards and ~e~odologies Section 3.1.0.
South Platte River Standards (Section
3.8) establish numeric standards for the
South Platte River Basin based on use
classificatioDS for stream segments.
8-66
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Table 8-3
ARARs for OUs 4&S
Page 3 of8
Citation Description Evaluation
:;:::::::::I:::::::::t::::::::I:::::=:::=::::::::::::::::::@::::::::::::';::::::=:':::=:::::::::::::::::::::J;~~~!:~~ik¥it~::=~B~~::~~~i:::i:::):{.:::.:..:=\<:::::/)\H:....""
Massachusetts Establishes health-based air standards. TBCs. These standards were used to design the SWRA
Allowable Ambient Levels when considering air pollution controls for the water treat-
(AALs) and Threshold ment plant. The plant will continue to meet these standards.
Effects Exposure Limits
(I'ELs)
~f!~~~~~~!j~jt~~~tf~~~~~~i~~~~r~[~!~~~~~~~~t~~J~r~f!~fij[~:j1~ftr~~~~~$~~I~!~~~!~~~tt~~~r~f~~~~~fj~;:;~;~;~~~;~;;;~;~;:;;::::::;:::::::. "',':...::" . .. :.:...::}::;!:~:::::~:~;:'. . ".',",.:"" .....
Solid Waste Disposal Act- RCRA Subtitle C Regulations
Defines those solid wastes that are The State of Colorado has an approved delegated program
subject to regulation as hazardous for this portion of RCRA. The regulations are applicable
wastes under 40 CFR Parts 262-265 for purposes of determining whether any of the materials
and Parts 124, 270, 271. being treated or disposed are hazardous wastes. Materials
may also be compared to the waste listings to determine
whether any of the materials are sufficiently similar such
that RCRA regulations are relevant and appropriate.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment plant residuals. Therefore, waste generated must
meet these standards which include testing per 40 CFR Part
261, temporary tanks or containers, inspection and leak
detection, and accumu1ation time. The State of Colorado
has an approved, delegated program under RCRA.
Because remediation activities constitute treatment and
storage activities (ground-water treatment plant and residuals
management), and because the water to be treated is
sufficiently similar to RCRA hazardous waste such that use
of the requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment component of the remedy (including residuals
management). Thus, ~tment of the groundwater must
meet these standards, which include waste analysis, site
security, emergency control and response equipment, per-
sonnel training, contingency planning and implementation.
Because ground-water treatment constitutes treatment of a
waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is well suited to the situa-
tion, the requirement is relevant and appropriate to the
ground-water treatment component of the remedy. There-
fore, closure and post~losure care for this treatment system
must meet these standards which include removal of waste,
waste residues, contaminated system components, and
contaminated subsoils; or closure with wastes and/or con-
tamination in place with containment systems and post-
closure care to include ground-water monitoring and inspec-
tion and maintenance on containments and monitoring
systems.
[[["
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40 CFR Part 260-261
Identification and Usting of
Hazardous Waste
40 CFR Part 262
Standards Applicable to
Generators of Hazardous
Waste
40 CFR Part 264 Subparts
B, C, and D
Standards for Owners and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
Establishes standards for RCRA
generators.
Establishes minimum standards that
define the acceptable management of
hazardous waste for owners and opera-
tors of facilities which treat, store, or
dispose of hazardous waste.
-------
Citation
.",',',', -"""'''''''''''''''''''',. ::;:::;;:;:::::;=;:::::;;::?
:[;i~iiii;ij~~iiif;ijiii~~i~~~iU::Ht:t:::;::::::::: ....
40 CFR Part 264
Subpart I
40 CFR Part 264
Subpart J
40 CFR 265.17
40 CFR Part 268
Land DisposaI Restrictions
40 CFR, Part 2301231
Guidelines for Specification
of Disposal Sites for
Dredged or Fill Materials
DEN1OOI5389.WP5
Table 8-3
ARARs for OUs 4&5
Description Evaluation
..... ..:.Aiii:~~.... :::.$~~:ii~::::::::rF;~~alY~~~i:!:!::::i!!i!:.!!!::i!:!i:!i!:!:!::i!i!i!:'i:i::!::?!:;!!!!!:!'ii!:'i:!:!ii,:,i!i:!!i!:::!ii:::':'!}:i!!i!:!,!i!'!
...'"
Sets operating and performance stan- Because ground-water treatment includes SIOrage in contain-
dards for container SIOrage of hazard- ers of a waste that is sufficieD1ly similar to RCRA hazard.
ous waste. ous waste such that use of the requirement is well suited to
the situation, the requirement is relevant and appropriate to
the ground-water treatment component of the remedy.
Therefore, container storage at the ground-water treatment
plant must meet these standards, which include maintaining
wastes in containers that are in good condition and compati-
ble with the wastes they contain, providing a containment
system, managing ignitable and reactive wastes away from
the property line, keeping incompatible wastes in separate
containers and containment systems, and at closure remov-
ing aU wastes and decontaminating structures and
equipment.
Because ground-water treatment includes SIOrage in tanks of
a waste that is sufficiently similar to RCRA hazardous waslc
such that use of the requirement is well suited to the situa-
tion, the requirement is relevant and appropriate to the
ground-water treatment component of the remedy. There-
fore, tank storage at the ground-water treatment plant must
meet these standards, which include secondary containment;
spill and overflow controls; removal from service if there is
a leak, spill, or the tank is unfit for use; and at closure have
aU wastes removed and also remove or decontaminate waslc
residues, containment system, soils, structures, and
equipment.
Because the ground-water treatment plant will mix and !!eat
potentially incompatible, reactive, or ignitable wastes which
may be similar to hazardous wastes, the requirement is
relevant and appropriate to the ground-water treatment
plant. Therefore, the wastes must be analyzed to determine
compatibility, reactivity, and ignitability before treatment in
the treatment plant.
Because the residuals from the ground-water treatment plant
operations will be land disposed, the requirement is
applicable. The materials must be tested to determine if
they are a characteristic hazardous waste (per 40 CFR Part
262) and then must meet treatment requirements for land
disposal as required in the standards if they are hazardous
waste for which a treatment standard bas been established.
For land disposal of residuals, other than soils, which are
not characteristic hazardous wastes, these requirements are
relevant and appropriate because the residuals are
sufficiently similar to listed hazardous waste such that use of
the requirements is well suited to the situation.
Federal Water PoDntion CODtroI Ad (amended by tbe Cleaa Water Ad)
The discharge of dredged or fill Wetlands were destroyed during construction of the SWRA
material into the waters of the U.S. is and must be mitigated during implementation of the selected
prohibited without a permit. remedy by constructing new wetlands.
....
Sets operating and performance stan-
dards for tank SIOrage of hazardous
waste.
Sets standards for mixing and treatment
of contaminated soils or the mixing and
treatment of poteatially incompatible,
reactive, or ignitable hazardous wastes.
Establishes prohibitions on land
disposal unless treatment standards are
met or a "DO migration exemption" is
granted.
8-68
Page 4 of8
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Table 8-3
ARARs for OUs 4&S
pagesofsl
Citation Descriptioo Evaluation
,.. .... ..."'" ...........
::::::::::::~::::::::::::~:::::::::::::::::I::t::::::::::::::::::::::::::::::::::::::::::::::::~::::::::::::::}?::J~~~iti./~Bf.~r~M~~f)::::::::::.::::::::::::;':::::()::::',::<:':<::=::;::;:;:::::
40 CFR., Part 440 Establishes radioDUclide concentration Because the effluent from the ground-water treatment plant
Effluent Guidelines and limits for liquid effluents from facilities could have radionuclides sufficieDlly similar to those
Standards for Ore Mining that extract and process uranium, regulated such that the requirement is well suited to the
and Dressing Point Source radium, and vanadium ores. situation, the requirement is relevant and appropriate to the
Categories ground-water treatment plant effluent. Therefore,
contingencies have been made for the early detection of
radionuclides and for a treatment process to be added to
treat radioDUclides at the ground-water treatment plant.
Clean Air Act
40 CFR. Part 61
National Emission
Standards for Hazardous
Air Pollutants (NESHAPs)
40 CFR. Parts 144-147
Underground Injection
Control Regulations
Establishes emission SWldards for
hazardous air pollutants from specific
sources.
Because the ground-water treatment plant has an air stripper
that is a source of air emissions, and this source is
sufficieDlly similar to source types in the regulations such
that use of the requirement is well suited to the situation,
the requirement is relevant and appropriate to the ground-
water treatment plant. Therefore, the air stripper must meet
these standards which include treatment levels for arsenic,
beryllium, benzene, vinyl chloride and radionuclide
emissions.
Safe DriDking Water Act
Establishes standards for construction Applicable to ~ection of water from treatment plant. The
and operation of injection wells. requirements include constructing, operating, and
Provides for protection of underground maintaining a well in a manner that does not result in
sources of drinking water. contamination of an underground source of drinking water
at levels that violate MCLs or otherwise affect the health of
persons. These requirements will be met by ensuring the
effluent from the groundwater treatment plant meets
SWldards that are protective of human health (based on
MCLs and risk-based concentrations).
. '"''''''''''''''
..............".. -
..... ........... ...
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.".,..,.....,........,....... ....... ,... .... . .
::r::::::m::f:(::}(:j::;:::j::~:::f~:::::::~:::::::::::::::I:::~~~*~::::
Colorado Hazardous Waste Act
..... .
..
~i(\t~t::::... ,':',',': ;.:':::::.. .:~:::~:~:~r:f~:~?:::r~;
............
6 CCR. 1007-3 Part 260-261 Defines those solid wastes subject to
Identification and listing of hazardous waste regulations.
Hazardous Waste
6 CCR.l007-3 Part 262
Standards Applicable to
Geuerators of Hazardous
Waste
DEN10015389.WPS
Establishes standards for RCRA
geuerators.
The State of Colorado has an approved delegated program
for this portion of RCRA. Applicable to determining
whether substances are hazardous wastes under RCRA.
Because remediation activities will generate waste that will
be sufficieDlly similar to RCRA hazardous waste such that
use of this requirement is weD suited to the situation, the
requirement is relevant and appropriate to the ground-water
treatment plant residuals. Therefore, waste generated must
meet these SWldards which include testing per 40 CFR. Part
261, temporary tanks or containers, inspection and leak
detection, offsite shipping procedures, and accumulation
time. The State of Colorado has an approved, delegated
program under RCRA.
8-69
-------
Table 8-3
ARARs for OUs 4&5
Page hfS
I
Description
..:::.......iiiii:'::ii~~I¥9t#':~::,:::$i;~(!::ii(~@riii::::ii:i:i:::r:::i:::::::::::::i:::::::i::i:::::i::::i:::!::::::i:i~i:::!::::::::::!::!!:::::::!::::::i!i::ii:::::i:::::::::::;:::':
Establishes miDimum standards that Because remediation activities constitute treatmem and
define the acceptable management of storage activities (ground-water treatmem plaDt and residuals
hazardous waste for owners and managemem), and because the water to be treated is
operators of facilities which treat, sufficiently similar to RCRA hazardous waste such that use
store, or dispose of hazardous waste. of the requiremem is well suited to the situation, the
requirement is relevaDt and appropriate to the ground-water
treatmeDt componem of the remedy (mcluding residuals
management). Thus, treatment of the groundwater must
meet these standards, which include waste analysis, site
security, emergency control and response equipment,
personnel training, contingency planning and
implementation.
Because ground-water treatment constitutes treatmem of a
waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is well suited to the
situation, the requiremem is relevaDt and appropriate to the
ground-water treatment componem of the remedy.
Therefore, closure and post
-------
Page dl
Table 8-3
ARABs for OUs 4&S
Citation Description
:::r:::::::::,::'::,:::::::::::::::::U:::::::::::::U':::':'::::::::':::::::::::::::::::::::::::::::::::::I':':':::~~~"~7~~:'::(~~~"':)}\:::...... .'H:\:,)':::,:;:,):///......:::;:::::::
6 CCR. 1007-3 Part 265.17 Sets standards for mixing and treatment Because the ground-water treatment plant will mix and treat
of contaminated soils or the mixing and potentially incompatible, reactive, or ignitable wastes which
treatment of potentially incompatible, may be similar to hazardous wastes, the requirement is
reactive, or ignitable hazardous wastes. relevant and appropriate to the ground-water treatment
plant. Therefore, the wastes must be analyzed to determine
compatibility, reactivity, and ignitability before treatment in
the treatment plant.
Because the residuals from the ground-water treatment plant
will be land disposed, the requirement is applicable. The
materials must be tested to determine if they are a
characteristic hazardous waste (per 6 CCR. 1007-3 Part 262)
and then must meet treatment requirements for land disposal
a8 required in the standards if they are hazardous waste for
which a treatment standard has been established. For land
disposal of residuals, other than soils, which are not
characteristic hazardous wastes, these requirements are
relevant and appropriate because the residuals are
sufficiently similar to listed hazardous waste such that use of
the requirements is well suited to the situation.
Colorado Air Quality Ad} Air PoDution Regulations
Requires filing of Air Pollution These regulations are applicable because air emissions will
Emission Notice (APEN) including occur at the treatment plant. The air stripper/carbon
estimation of emission rates. polishing treatment process must meet any substantive
provisions of these requirements.
These regulations are applicable because air emissions will
occur at the treatment plant. The air stripper/carbon
polishing treatment process must meet these requirements
which include discharge and performance rates and opacity
requirements.
These regulations are applicable because air emissions will
occur at the treatment plant. The air stripper/carbon
polishing treatment process must meet these requirements
which include controls representing reasonably available
control technology (RACI).
Colorado Noise Abatement Statute
Provides limits for noise based on time Applicable for all construction activities associated with the
periods and zones. remedy.
:':!::i!:::!::::,:::!::::::::::!!t:::::::::,:t,,::m:::@:,:!:::::!i:::!::::::::::::::i::;::::I'j::::::::::U!:::::::::~#f$@['~'::~*~~~D,:::::::::{::::"::::::::::,::::::::: t::::::f:::':::::::::U::::::::'::::::::::::::::U':'::!::.::U::::::::::::::::
Execntive Order 11990, Protection of Wetlands
40 CFR. Part 6, Appendix A Action to avoid adverse effects, Applicable because wetlands have been identified and
minimize potential harm, and preserve destroyed at the Lowry Site during the SWRA. New
and enhance wetlands, to the extent wet1ands will be constructed as part of the remedy.
poasible. Requires action to minimize
the destruction, loas,or degradation of
wetlands.
Evaluation
6 CCR. 1007-3 Part 268
Land Disposal Restrictions
Establishes prohibitions on land
disposal unless treatment standards are
met or a "no migration exemption" is
granted.
5 CCR. 1001-5
Regulation No.3
5 CCR. 1001-8
Regulation No.6
Establishes standards for new stationary
sources including incinerators. Sets
discharge and performance rates and
opacity requirements.
5 CCR. 1001-9
Section II.C.2, Section V
Regulation No.7
Establishes standards for disposal or
spillage of VOCs.
Colorado Revised Statute
Section 25-12-103
Federal Water PoDution CoDtnII Act (Clean Water Act)
Discharge of dredged or 611 material For areas of the site that have designated wetlands, a permit
into wetlands prohibited without a will DOt be required pursuant to Section 121 (c) of
permit. CERCLA, but the substantive requirements of Part 230 will
be applicable if wetlands that have been identified at the
Lowry Site are dredged or filled during implementation of
the remedial activity.
40 CFR. Part 230
8-71
DENIOOIS389.WP5
-------
Citation
..... .
.. ......-..
....
... ..
5 CCR 1002-18
DEN10015389.WP5
....
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. "',','".
.......
. .
Table 8-3
ARARs for OUs 4&S
Page 8 o~
Description Eva1uatioo
"..""'.. '::::i:::::';:::::::~~~~~~Ii$:::~m$@~:::::::!::U\i!n::n:i::;:;(!:::::::!:::::i!'i!!:::::,!::::::!!:::::!::::!!':::i!i)::::::::::)i!::::{::::::)::;:::::it::;:::::
Certificatioo of Federal Liceases and Permits
Discharge of dredge and till material
into wetlands prohibited without a State
certification.
8-72
For areas of the site that have designated wetlands, a pel'lllit
will not be required pul'SUllDt to Section 121(c) of
CERCLA, but the substantive requirements will be
applicable if wetlands that have been identified at the Lowry
Site are dredged or tilled during implementation of the
remedial activity.
-------
Section 9.0
Summary of the Comparative Analysis of Alternatives
-------
Section 9.0
Summary of the Comparative Analysis of Alternatives
This section compares the remedial alternatives described in Section 8.0. The compara-
tive analysis provides the basis for determining which alternative presents the best balance
between the EPA's nine evaluation criteria listed below. The first two cleanup evaluation
criteria are considered threshold criteria that must be met by the selected remedial action.
The five primary balancing criteria are balanced to achieve the best overall solution.
The final two modifying criteria that are considered in remedy selection are State accep-
tance and community acceptance.
.
.
6.
DENlOOI53AB.WP5
Threshold Criteria
1.
Overall Protection of Human Health and the Environment
addresses whether a remedy provides adequate protection and
describes how risks posed through each pathway are eliminated,
reduced, or controlled.
2.
Compliance with Applicable or Relevant and Appropriate
Requirements addresses whether a remedy will meet all Federal
and State environmental laws and/or provide grounds for a waiver.
Primary Balancing Criteria
3.
Long-Term Effectiveness and Permanence refers to the ability of
a remedy to provide reliable protection of human health and the
environment over time.
4.
Reduction of Toxicity, Mobility, or Volume Through Treatment
refers to the preference for a remedy that reduces health hazards of
contaminants, the movement of contaminants, or the quantity of
contaminants at the Lowry Site through treatment.
5.
Short- Term Effectiveness addresses the period of time needed to
complete the remedy, and any adverse effects to human health and
the environment that may be caused during the construction and
implementation of the remedy.
hnplementability refers to the technical and administrative feasi-
bility of an alternative or a remedy. This includes the availability
of materials and services needed to carry out a remedy. It also
includes coordination of Federal, State, and local government
efforts.
9-1
-------
7.
Cost evaluates the estimated capital, operation, and maintenance
(O&M) costs of each alternative in comparison to other equally
protective alternatives.
.
Modifying Criteria
8.
State Acceptance indicates whether the State agrees with, opposes,
or has no comment on the preferred alternative.
9.
Community Acceptance includes determining which components of
the alternatives interested persons in the community support, have
reservations about, or oppose.
The strengths and weaknesses of the alternatives were weighed to identify the alternative
providing the best balance among the nine evaluation criteria. The comparative analysis
of alternatives for OUs 1&6, 2&3, and 4&5 is provided in the following discussion.
9.1 OU 1: Shallow Ground Water and
Subsurface Liquids and
OU 6: Deep Ground Water
9.1.1 Threshold Criteria
9.1.1.1 Overall Protection of Human Health and the Environment
The NCP requires that all alternatives be assessed to determine whether they can
adequately protect human health and the environment, in both the short- and long-term,
from unacceptable risks posed by hazardous substances, pollutants, or contaminants
present at the site by eliminating, reducing, or controlling exposures to such hazardous
substances, pollutants, or contaminants. Overall protection of human health and the
environment draws on the assessments of other evaluation criteria, especially long-term
effectiveness and permanence, short-term effectiveness, and compliance with ARARs.
All of the alternatives would be protective of human health and the environment, with the
exception of the No Action alternative. The No Action alternative would not be
protective because contamination above ARARs and other performance standards would
migrate offsite and downward into the major water supply aquifers. Therefore, the No
Action alternative will not be considered further in this evaluation.
All other alternatives would be protective because they would: prevent migration of
contaminants above performance standards beyond the compliance boundary through
containment and collection and/or through monitoring and implementation of
contingencies; meet ARARs; prevent exposure to contaminants within the compliance
boundary through the use of institutional controls; monitor for vertical migration of
DENlOO153AB.WP5
9-2
-------
contaminants and implement contingencies to contain such vertical migration; monitor the
effectiveness of remedial measures.
The following analysis is structured such that the alternatives are discussed in order of
relative protectiveness. The comparison of alternatives shows that for overall
protectiveness, Modified Alternative Groundwater No.5 (GW-5) (the North Boundary,
Toe of Landfill and Lateral Barrier Walls Collection and Treatment System, plus
Upgradient Containment Collection and Treatment alternative) is superior to all other
alternatives. This is because it is the only alternative which does not rely on
contingencies to prevent lateral migration of contaminated ground water from the Lowry
Site. Instead, Modified Alternative GW-5 includes barrier walls and collection systems
on all boundaries of the Lowry Site. All other alternatives rely to one degree or another
on monitoring at the boundaries and would require further action if monitoring revealed
offsite migration of contaminants above performance standards.
This distinction between Modified Alternative GW-5 and the other alternatives is
important because contaminants have been detected at the western and southern portions
of the Lowry Site near the compliance boundary, and ground-water modeling performed
for the risk assessment and feasibility studies indicates that offsite migration will occur.
By requiring the immediate design and installation of barrier walls on the eastern,
western and southern boundaries, and upgrading of the existing barrier wall or
construction of an additional barrier wall on the northern boundary of the Lowry Site,
Modified Alternative GW-5 provides the greatest assurance that performance standards
will be achieved at the compliance boundary.
Like Modified Alternative GW-5, Alternative GW-5 (the North Boundary, Toe of
Landfill plus Lateral Containment, Collection and Treatment alternative) includes
containment systems on the eastern and western boundaries. However, Alternative GW-5
lacks Modified Alternative GW-5's upgradient containment feature on the southern
boundary of the Lowry Site and would require further action if monitoring revealed
migration of contaminants at the southern boundary.
Modified Alternative GW-5's upgradient system would result in the following benefits to
human health and the environment:
.
Prevention of migration of contaminants southward from the landfill mass
resulting from localized ground-water flow to the south. As noted above,
contaminants have been detected near the southern compliance boundary.
Local southward flow could be caused by mounding from the landfill,
unidentified sand stringers/sand channels, and other geologic
heterogeneities, chemical diffusion, dispersion, and possible unidentified
localized seasonal changes in ground-water flow direction.
.
Reduction of ground-water inflow from the south entering the contaminated
Site. This would reduce the volume of clean water that is mixed with
contaminated water and thereby reduce the ground-water treatment cost.
DENl00lS3AB.WPS
9-3
-------
Like Modified Alternative GW-5, Alternative GW-4 (the North Boundary, Toe of
Landfill,.Upgradient Containment, Collection, and Treatment, plus ~ultilayer Cap.
alternative) includes installation of the upgradient ground-water contamment, collection,
and diversion system. However, Alternative GW-4 lacks the barrier walls on the eastern
and western boundaries and would require further action if monitoring revealed migration
of contaminants at the eastern and western compliance boundaries.
Unlike Modified Alternative GW-5, Alternative GW-4 requires installation of a multilayer
cap. However, the existing clay cap is effective in preventing infiltration from
precipitation into the landfill mass and waste-pit liquids. Modeling results show that
placement of the multilayer cap in Alternative GW-4 would not reduce the infiltration rate
any more than the current clay cap. Therefore, the multilayer cap in Alternative GW-4
would not provide any additional protection of human health and the environment than
the existing clay cap.
Unlike the other alternatives, Alternative GW-6 (the North Boundary and Toe of Landfill
Containment, Collection and Treatment plus Waste-Pit Pumping alternative) includes
pumping and treatment of waste pit liquids. However, only a small portion of the waste
pit liquids could be extracted and the waste pit liquids would continue to act as a source
for ground water contamination. Alternative GW-6 does not include containment systems
on the eastern, western, and southern boundaries, and thus, is not considered to be as
protective as the alternatives which include such systems.
Like Alternatives GW-4, GW-5, GW-6 and Modified Alternative GW-5, Alternative GW-
3 (the North Boundary and Toe of Landf1l1 Containment, Collection, and Treatment
alternative) includes a toe of the landfill collection system. This system provides an
additional measure of protectiveness over alternatives which don't include the system by
preventing the most highly contaminated liquids from migrating northward and further
degrading ground water between the landfill mass and the northern compliance boundary.
This system is an extra safety measure which, among other things, would limit the
negative impacts if there were ever a breakthrough of contaminated ground water at the
northern barrier wall. Alternative GW-3 does not include containment systems on the
eastern, western, and southern boundaries, and thus, is not considered to be as protective
as the alternatives which include such systems.
Like Modified Alternative GW-5 and some of the other alternatives, Alternative GW-2
(the North Boundary Containment Collection and Treatment alternative) would extend the
existing barrier wall on the northern boundary or build a new longer barrier wall adjacent
to the existing one. This feature would provide an additional measure of protectiveness
over Alternative GW-I (the No Further Action alternative) by providing greater assurance
that contaminants would be captured at the northern compliance boundary and would not
move around the edges of the barrier wall. Neither Alternative GW-2 nor Alternative
GW-I include containment systems on the eastern, western, and southern boundaries or
toe of the landfill collection. Thus, they are not considered to be as protective as the
alternatives which include such systems.
DENlOOI53AB.WP5
9-4
-------
9.1.1.2 Compliance with ARARs
Applicable requirements are those cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated under Federal or State law
that specifically address a hazardous substance, pollutant, contaminant, remedial action,
or location at a CERCLA site. Relevant and appropriate requirements are similar
requirements that, while not applicable, clearly address problems or situations sufficiently
similar to those encountered at a CERCLA site such that their use is well suited to the
particular site.
The alternatives were assessed to determine whether they would attain applicable or
relevant and appropriate requirements under Federal environmental laws and State envi-
ronmental or facility siting laws or provide grounds for invoking an ARARs waiver.
The ARARs for OUs 1&6 alternatives are discussed in Section 8.0.
All of the alternatives would meet ARARs. Modified Alternative GW-5 and Alternative
GW-5 are the only alternatives that would include control of lateral migration as a princi-
pal component to achieve compliance with ARARs at the eastern and western compliance
boundaries. These alternatives would also be superior in meeting the intent of the closure
provisions for RCRA hazardous waste landfills, which are considered relevant and appro-
priate at the Lowry Site.
The conclusion that each alternative can meet the ARARs is based on treatability study
results. Contingencies would be implemented if performance data showed that the
selected remedy was not achieving ARARs. Contingencies would include any or all of
the following:
.
If, during implementation or operation of the ground-water remedy, it was
determined that contaminant levels exceeded the performance standards at
the point of action boundary, the remedy would be re-evaluated and
modifications made to prevent contaminant migration beyond the
compliance boundary. Modifications might include any or all of the
following, at EPA's discretion:
Alternating pumping at wells to eliminate stagnation points
Pulse pumping to allow aquifer equilibration and to allow adsorbed
contaminants to partition into ground water
Installation of extraction wells to facilitate containment of the
contaminant plume and to address possible vertical migration of
contaminants and alternate pumping at these wells to eliminate
ground water stagnation points
DENlOO153AB.WP5
9-5
-------
To ensure that performance standards would continue to be maintained, the
aquifer would be monitored at appropriate locations and frequencies, as
determined by EPA.
.
If it were determined by EPA, on the basis of the system performance
data, that contaminants had migrated vertically downward to the lignite
layer, contingency measures would be implemented to ensure that the
beneficial use of the underlying aquifer would not be impaired. The
following measures involving long-term management might be required, at
EPA's discretion, for an indefinite period of time, as a modification of the
existing system:
Additional engineering controls such as underground barriers, or
long-term gradient control provided by low level pumping, as con-
tainment measures
Continued monitoring of specified wells
Periodic re-evaluation of remedial technologies for ground-water
restoration
Additional institutional controls on water extraction and use
.
Contingencies for the SWRA, which are relevant to the operation of the
GWTP, were developed as part of the SWRA design and are discussed in
Subsection 11.5.2. These contingencies would be reviewed during the
selected remedy design and, if necessary, modified or upgraded.
Contingency plans would be developed in detail during the RD. These plans would
address measures to be taken if ARARs are not met.
9.1.2 Primary Balancing Criteria
9.1.2.1 Long-Term Effectiveness and Permanence
The alternatives were assessed for the long-term effectiveness and permanence they
afford, along with the degree of certainty that the alternative would prove successful.
Factors that were considered include the following:
DENlOOlS3AB.WP5
1.
The magnitude of residual risk remaining from untreated waste or treat-
ment residuals remaining at the conclusion of the remedial activities; and
2.
The adequacy and reliability of controls such as containment systems and
institutional controls that are necessary to manage untreated waste and
treatment residuals.
9-6
-------
All of the alternatives would offer long-term effectiveness and permanence and address
the movement of contaminants to the north (the primary migration pathway) through
treatment of ground water collected at the existing barrier wall system. However,
Modified Alternative GW-5 would best address long-term effectiveness and permanence
through up-front construction of containment and collection systems on all sides of the
Lowry Site.
Modified Alternative GW-5 and Alternative GW-5 are the only alternatives that would
immediately prevent potential offsite migration of contaminants to the east and west. In
addition, Modified Alternative GW-5 and Alternative GW-5 provide additional long-term
effectiveness and permanence above Alternatives GW-l, 2, 3, and 4, because they extract
waste from the east and west sides of the landfill mass.
Alternative GW-6 would extract more subsurface liquids from the landfill; however,
because only a small fraction of the waste pits would be extracted, the waste pit liquids
would still act as a continual source for ground-water contamination. Therefore,
Alternative GW-6, although better at extraction, would not offer any significant additional
long-term effectiveness and permanence over Modified Alternative GW-5 or Alternative
GW-5.
Like Alternatives GW-5 and GW-6 and Modified Alternative GW-5, Alternatives GW-3
and GW-4 would reduce risk through treatment of the highly contaminated ground water
collected at the toe of the landfill. Collection of the contaminated ground water at the toe
of the landfill would capture contamination closer to the source and avoid further
contamination of the aquifer downgradient of the landfill mass.
Alternative GW-4 and Modified Alternative GW-5 offer upgradient containment,
collection, and diversion, which reduces the inflow of clean water mixing with
contaminated water and also prevents southern offsite migration. Alternative GW-4 adds
a multilayer cap, but this has not been shown to be any more effective in inhibiting
infiltration of surface water into the Lowry Site than the existing clay cap.
Alternatives GW-l (the No Further Action alternative) and GW-2 (the North Boundary
Containment, Collection, and Treatment alternative) would be the least effective
alternatives because they rely on contingency measures for eastern, western, and southern
compliance boundary exceedances and would not capture and treat contamination as close
to the source area as the remaining alternatives which use toe of the landfill ground-water
extraction and treatment. Modified Alternative GW-5 is the only alternative that fully
contains migration to the north, east, west, and south, as well as effectively reduces the
long-term potential for contaminated ground-water migration.
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9.1.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
The degree to which alternatives employ recycling or treatment to reduce toxicity, mobil-
ity, or volume was assessed, including how treatment wou~d be u~ed to address the.
principal threats posed by the site. Factors that were considered mclude the folloWIng:
1.
The treatment or recycling processes the alternatives employ and materials
they will treat;
2.
The amount of hazardous substances, pollutants, or contaminants that will
be destroyed, treated, or recycled;
3.
The degree of expected reduction in toxicity, mobility, or volume of the
waste from treatment or recycling and the specification of which reduc-
tion(s) are occurring;
4.
The degree to which the treatment is irreversible;
5.
The type and quantity of residuals that will remain following treatment,
considering the persistence, toxicity, mobility, and propensity to
bioaccumulate of such hazardous substances and their constituents; and
6.
The degree to which treatment reduces the inherent hazards posed by prin-
cipal threats at the site.
All of the alternatives would reduce the toxicity, mobility, or volume of contaminated
ground water migrating to the north through extraction and treatment at the existing
barrier wall. The alternative that would best achieve this criterion is Alternative GW-6,
because it includes extraction and treatment of waste-pit liquids and extraction and
treatment of highly contaminated ground water in the alluvium at the toe of the landfill.
Alternatives GW-3, GW-4, GW-5, and Modified Alternative GW-5 would be next best at
reducing toxicity, mobility, or volume through treatment, because they would provide for
extraction of highly contaminated ground water in the alluvium at the toe of the landfill.
Alternative GW-l (the No Further Action alternative) and Alternative GW-2 (the North
Boundary Containment, Collection, and Treatment alternative) have the least reduction of
mobility, toxicity, or volume through treatment because contamination is allowed to
migrate beyond the toe of the landfIll until it is captured at the northern site boundary.
9.1.2.3 Short-Term Effectiveness
The NCP considers the following four features as components of short-term effectiveness:
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Short-term risks to the community during implementation
Potential impacts to workers during implementation
.
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.
Potential environmental impacts during remediation
Time until protection is achieved
.
All of the alternatives would have reasonable short-term effectiveness. Alternative GW-l
(the No Further Action alternative) and Alternative GW-2 (the North Boundary
Containment, Collection, and Treatment alternative) would have no adverse short-term
effects. The remaining Alternatives, GW-3, GW-4, GW-5, Modified Alternative GW-5,
and GW-6, would include a ground-water extraction system at the toe of the landfill for
highly contaminated ground water. During construction of this system, construction
workers would be exposed to higher risks from the potential presence of volatile organic
compounds in the soil. However, these risks are not anticipated to be significant during
the 3-year design and construction period.
With the exception of measures that may be required during construction of the trench at
the toe of the landfill, the use of unusual or special construction techniques is not
anticipated. It has been demonstrated that workers at the Lowry Site can be adequately
protected during construction through routine application of accepted Occupational Safety
and Health Administration (OSHA) health and safety practices. The majority of the
construction would not require special health protective measures.
None of the alternatives would pose short-term risks to the community during
implementation or cause adverse environmental impacts during remediation.
While potential impacts to workers might be greater with Modified Alternative GW-5
than with Alternatives GW-I and GW-2, Modified Alternative GW-5 would achieve
overall protection in a shorter time frame than these alternatives because containment
systems would be immediately designed and installed on the eastern, western, and
southern sides of the Lowry Site. Thus, from an overall perspective, Modified
Alternative GW-5 is as effective in the short-term as Alternatives GW-l and GW-2.
Likewise, Alternatives GW-5 and GW-4, which both include lateral containment on the
west and east or the south, offer advantages over Alternatives GW-l and GW-2 in terms
of the amount of time required until protection is achieved.
9.1.2.4 Implementability
The ease or difficulty of implementing the alternatives was assessed by considering the
following types of factors:
1.
Technical feasibility, including technical difficulties and unknowns associ-
ated with the construction and operation of a technology, the reliability of
the technology, ease of undertaking additional remedial actions, and the
ability to monitor the effectiveness of the remedy.
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2.
Administrative feasibility, including activities needed to coordinate with
other offices and agencies and the ability and time required to obtain any
necessary approvals and permits from other agencies (for offsite actions);
Availability of services and materials, including the availability of adequate
off-site treatment, storage capacity, and disposal capacity and services; the
availability of necessary equipment and specialists, and provisions to
ensure any necessary additional resources; the availability of services and
materials; and availability of prospective technologies.
3.
All of the alternatives are considered to be administratively and technically implement-
able. In addition, the services and materials required to implement all of the alternatives
would be readily available. Alternative GW-1 (the No Further Action alternative) and
Alternative GW-2 (the North Boundary Containment, Collection, and Treatment alterna-
tive) would be the easiest to implement. Alternatives GW-3, GW-5, and Modified
Alternative GW-5 would all use current technology and would be the next easiest to
implement.
The construction of containment barrier walls that act to collect or divert are considered
routine construction and can be performed by local contractors. The effectiveness of the
ground-water treatment system is proven by the success of the existing treatment facility
located onsite.
Alternative GW-4 (the North Boundary, Toe of Landfill, Upgradient and Multilayer Cap
alternative) and Alternative GW-6 (the North Boundary, Toe of Landfill Containment,
and Waste-Pit Pumping alternative) are considered to be the least implementable
alternatives. This is because Alternative GW-4 proposes 100-foot-deep extraction
trenches that may be difficult to construct, and Alternative GW-6 includes drilling
52 waste-pit extraction wells that may be difficult to drill through landfill refuse.
9.1.2.5 Cost
The types of costs that were assessed include the following:
1.
2.
3.
Capital costs, including both direct and indirect costs;
Annual operation and maintenance costs; and
Net present value of capital and O&M costs.
A description of cost estimating procedures is provided in Section 8.1.
The No Further Action alternative would be the least costly, while Alternative GW-4
(North Boundary, Toe of Landfill, Upgradient Containment Collection and Treatment
~lus. Multilayer Cap alternative) would be the most costly. 'Modified Alternative GW-5 is
sIgmficantly less expensive than Alternative GW-6 and is more expensive than Alternative
GW-3. Modified Alternative GW-5 is comparable in costs to Alternative GW-5, but
DEN! OO153AB. WP5
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includes physical barriers and an additional upgradient ground-water collection,
containment, and diversion system. Modified Alternative GW-5 is more expensive than
Alternatives GW-l and GW-2 because Alternatives GW-l and GW-2 do not immediately
address offsite contaminant migration to the eastern, western, and southern site
boundaries.
Costs for ODs 1&6 alternatives are ranked below from least to most expensive based on
the following present worth estimates:
.
Alternative GW-l: No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$4,300,000
$1,800,000
$31,970,000
.
Alternative GW-2: North Boundary
(Downgradient) Containment, Collection,
and Treatment
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$9,800,000
$1,900,000
$39,010,000
.
Alternative GW-3: North Boundary and
Toe of Landfill Containment, Collection,
and Treatment
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$15,300,000
$3,000,000
$61,420,000
.
Alternative GW-5: North Boundary,
Toe of LandfIll, and Lateral Containment,
Collection, and Treatment
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$17,700,000
$3,000,000
$63,820,000
.
Modified Alternative GW-5: North
Boundary, Toe of Landfill, and Lateral
Containment, Collection and Treatment
plus Upgradient Containment, Collection,
and Diversion
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$19,000,000
$2,400,000
$65,030,000
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.
Alternative GW -6: North Boundary and
Toe of Landfill Containment, Collection
and Treatment, and Waste Pit Pumping
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$20,300,000
$3,400,000
$72,570,000
.
Alternative GW-4: North Boundary,
Toe of Landfill, and Upgradient
Containment, Collection and Treatment,
plus Multilayered Cap in Landfill Area
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$64,100,000
$3,200,000
$113,300,000
It should be noted that the cost figures for alternatives which rely on contingency
measures to address potential contaminant migration to the east, west, and/or south (all
alternatives other than Modified Alternative GW-5) do not include cost figures for such
contingency measures. If such contingency measures had to be initiated, the costs could
increase significantly for those alternatives.
9.1.3 Modifying Criteria
9.1.3.1 State/Support Agency
Acceptance (August 1993)
The State of Colorado concurs with the EP A on the selection of Modified Alterna-
tive GW-5 for ODs 1&6. The State of Colorado also concurs with the selected ARARs.
9.1.3.2 Community Acceptance
Community input on the alternatives for remedial action for ODs 1&6 was solicited by
BPA and CDH during the public comment period for the ODs 1&6 Proposed Plan from
November 23, 1992 to March 2, 1993. Comments from the public were supportive of
the preferred remedy. Several of the commenters recommended that EP A consider addi-
tional efforts to pump waste pits and several commenters were opposed to any use of
offsite institutional controls as a substitute for cleanup actions or which would prohibit
use of the surrounding lands. Responses to community comments are found in the
Responsiveness Summary for ODs 1&6 in Section 13.0 of this ROD. The PRPs were
generally supportive of the selected remedy. One set of PRPs was in favor of the
upgradient containment, collection and diversion system, while the other set of PRPs
asked for additional justification on the upgradient system. Responses to PRP comments
are found in the Responsiveness Summary for ODs 1&6 in Section 13.0 of this ROD.
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9.2 OU 2: Landfill Solids and
OU 3: Landfill Gas
9.2.1 Threshold Criteria
9.2.1.1 Overall Protection of Human Health and the Environment
Under the No Action alternative, Landfill Solids Alternative 1 (LFS-l), all of the
potential risks to human health and the environment associated with the landfill solids and
gas would remain. These include the excess risk of getting cancer from exposure to gas
migrating offsite, risks associated with the potential buildup and explosion of methane
gas, and risks associated with potential exposure to contaminated drums at or near the
land surface in the former tire pile area.
In addition, the existing clay cap would deteriorate without maintenance, which could
lead to inf1ltration of surface water into the landfill mass and a resultant increase in the
potential for migration of contaminants. EPA has determined that these risks are
unacceptable. Because the No Action alternative is not protective for either landfill solids
or landfill gas, it will not be considered further in this evaluation.
9.2.1.1.1 Landfill Solids (LFS). All of the alternatives would be protective of human
health and the environment because they would prevent exposure to contaminants in
landfill solids. This would be accomplished through the use of various combinations of
cover over, and excavation and treatment of, landfill solids, in conjunction with
institutional controls.
Modified Alternative LFS-4 (the Drum Removal/Offsite Disposal/North Face Cover
alternative) would be the most protective of human health and the environment. This is
because Modified Alternative LFS-4 requires the removal of the greatest volume of
contaminated materials in the former tire pile area, thereby providing the greatest risk
reduction and overall protection of human health and the environment. Moreover, Modi-
fied Alternative LFS-4 would provide additional protection by including an additional
2 feet of soil cover on the north slope of the former landfill. This cover would further
reduce potential exposure from landfill solids, thus reducing risks to human health and
the environment.
Alternative LFS-6 (the Drum Removal/Low-Temperature Thermal Desorption/
Stabilization and Disposal alternative) would be the second most protective of human
health and the environment because this alternative requires the removal and treatment of
the second greatest volume of contaminated materials (approximately 1,350 drums and
4,200 cubic yards of contaminated soil) in the former tire pile area. Like Modified
Alternative LFS-4, Alternative LFS-6 would include reclamation of excavated areas and
maintenance of soil cover in the former tire pile area. The existing cap over the landfill
mass would be maintained. However, this alternative does not include the additional 2
feet of soil cover on the north slope of the landfill.
DEN 1 001 53AB.WPS
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Alternative LFS-4 (the Drum Removal/Offsite Disposal alternative) would be the third
most protective of human health and the environment because this alternative requires the
removal and treatment of the third greatest volume of contaminated materials
(approximately 1,350 drums and contaminat~ soils adjacent. to t~e drums) in the former
tire pile area. Thus, risks would be reduced In the former tire pIle area, but not as much
as Alternative LFS-6 and Modified Alternative LFS-4. Alternative LFS-4 would include
the same cover elements as Alternative LFS-6 in the former tire pile area and the landfill
mass.
Alternative LFS-3 (Clay Cap alternative) would be slightly less protective than
Alternative LFS-4 because it would remove a lesser volume of contaminated materials
(approximately ten drums) in the former tire pile area and would not result in treatment
of those materials (instead they would be disposed of at an offsite RCRA Subtitle C
facility.) However, Alternative LFS-3 would include a clay cap in the former tire pile
area rather than a soil cover. This would provide a more substantial physical barrier to
contaminated landfIll solids in this area and thus reduce the potential for exposure.
The No Further Action (LFS-2) and Landfill Regrading (LFS-7) alternatives are consid-
ered to be least protective of human health and the environment because neither
alternative requires removal or treatment of contaminated materials. Alternative LFS-7
would include an additional 2 feet of clay on the north face of the landfill mass after
landfilling was completed.
9.2.1.1.2 lAndfiU Gas (LPG). Alternatives LFG-3, LFG-5, and Modified Alternative
LFG-3 would each be protective of human health and the environment. These
alternatives would ensure protectiveness by extracting gas from the landfill, thereby
preventing gas migration beyond the Lowry Site boundaries, and treating the gas.
Potentially dangerous buildups of methane would be prevented and migrating VOCs
would be captured and treated.
Modified Alternative LFG-3 (Gas Collection/Enclosed Flare) is the most protective of
human health and the environment. This is because Modified Alternative LFG-3 provides
greater short- and long-term risk reduction than other alternatives involving gas collection
because of the initial installation of a more comprehensive extraction system (Stage 1 and
Stage 2). Alternatives LFG-3 (Stage 1) and LFG-5 (Stage 1) would provide initial gas
extraction in localized areas in the western and southwestern portions of the landfill mass.
If gas continued to migrate from the landfill mass, Stage 2 of these alternatives would be
implemented.
Stage 2 includes the addition of gas extraction wells around the perimeter of the landfill
~ass. If Stage 2 of Alternative LFG-3 and Stage 2 of Alternative LFG-5 were
Implemented, Alternatives LFG-3 and LFG-5 would be as protective of human health and
the environment as Modified Alternative LFG-3. The No Further Action alternative
(LFG-2) would not be protective of human health and the environment because it would
not prevent gas migration from occurring.
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9.2.1.2 Compliance with ARARs
The ARARs for OUs 2&3 alternatives are discussed in Section 8.0.
9.2.1.2.1 Landfill Solids. All alternatives would meet ARARs except Alternative LFS-7
(Landfill Regrading). Alternative LFS-7 would not meet RCRA Subtitle D Solid Waste
Disposal Regulations (40 CFR Parts 257 and 258) and Regulations Pertaining to Solid
Waste Disposal Sites and Facilities (6CCR 1007-2) because standards for design and
construction would not be met.
9.2.1.2.2 Landfill Gas. All alternatives except the No Further Action alternative would
meet ARARs. The No Further Action alternative would not meet RCRA Solid Waste
Disposal Regulations (40 CFR Parts 241) because gas would migrate offsite above the
regulated limits.
9.2.2 Primary Balancing Criteria
9.2.2.1 Long-Term Effectiveness and Permanence
9.2.2.1.1 Landfill Solids. Modified Alternative LFS-4 would provide the greatest long-
term effectiveness and permanence because the former tire pile area would be excavated
and the largest volume of contaminated material would be removed relative to the remain-
ing alternatives. This would permanently remove contaminated material from the Lowry
Site. In addition, Modified Alternative LFS-4 would provide 2 feet of additional cover
on the north face of the landfill mass, thus providing greater containment and long-term
effectiveness and permanence in the landfill area.
Alternatives LFS-3, LFS-4, and LFS-6 would each provide a lesser level of effectiveness
in the landfill mass and the former tire pile area because these alternatives would remove
a smaller volume of contaminated material from the former tire pile area and would not
provide 2 feet of additional cover on the north face of the landfill mass. The alternatives
that would least meet this criterion are the No Further Action alternative (LFS-2) and
Alternative LFS-7 (Landfill Regrading) because they would remove no contaminated
material from the former tire pile area. Alternative LFS-7 would provide an additional 2
feet of cover on the north face of the landfill mass.
9.2.2.1.2 Landfill Gas. Modified Alternative LFG-3 would provide the greatest long-
term effectiveness and permanence because it would provide a more extensive gas
extraction system throughout the landfill mass, and it would be less dependent on gas
monitoring activities than other alternatives.
Alternatives LFG-3 and LFG-5 would be as effective in the long-term as Modified Alter-
native LFG-3 if Stage 2 of Alternative LFG-3 and Stage 2 of Alternative LFG-5 were
implemented. The No Further Action alternative (LFG-2) does not remove and treat gas
DENlOO153AB.WPS
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from the landfill and is therefore considered the least effective alternative. Over time,
gas wou.ld migrate offsite and pose a risk to human health and the environment.
9.2.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
9.2.2.2.1 Landfill Solids. Modified Alternative LFS-4 (the Drum RemovallOffsite
Disposal/North Face Cover alternative) would require excavation and treatment of the
greatest volume of contaminated solid material, and would thus provide the greatest
reduction of toxicity, mobility, and volume of contaminants through treatment. The
toxicity, mobility, and volume of liquids in drums would be reduced through incineration
and the mobility of other excavated materials would be reduced through stabilization.
Alternative LFS-6 (the Drum Removal/Low-Temperature Thermal Desorption/
Stabilization/Disposal alternative) requires the excavation and treatment of the next
greatest volume of contaminated solid material and would thus provide the next greatest
reduction of toxicity, mobility, and volume of contaminants through treatment. This
alternative would incinerate the same volume of liquids from drums as Modified
Alternative LFS-4, but would treat a lesser volume of soils (4,200 cubic yards versus
15,000 cubic yards.) Treatment for the soils would consist of low temperature thermal
desorption.
Alternative LFS-4 (the Drum Removal/Offsite Disposal/North Face Cover alternative)
would provide the next greatest reduction in toxicity, mobility, and volume through
excavation and offsite treatment. The same volume of liquids in drums would be
incinerated, but a lesser volume of soils would be treated than with either Modified
Alternative LFS-4 or Alternative LFS-6.
Alternative LFS-3 (Clay Cap alternative), Alternative LFS-2 (No Further Action
alternative), and Alternative LFS-7 (Landfill Regrading alternative) would provide no
reduction of toxicity, mobility, or volume through treatment.
9.2.2.2.2 Landfill Gas. Modified Alternative LFG-3 would provide a greater reduction
of toxicity, mobility, and volume through treatment than other alternatives by extracting
and treating more gas from the eastern, western, and southern portions of the landfill
mass than the remaining alternatives. Alternatives LFG-3 (Stage 1) and LFG-5 (Stage 1)
would provide for the next greatest reduction in toxicity, mobility, and volume through
the treatment of landfill gas in the western and southwestern portions of the landfill mass.
Alternatives LFG-3 and LFG-5 would provide the same reductions of toxicity, mobility,
or volu~e through treatment as Modified Alternative LFG-3 if Stage 2 of
Alternative LFG-3 and Stage 2 of Alternative LFG-5 were implemented. Alternative
LFG-2 (No Further Action) would provide no reduction in toxicity, mobility, or volume
through treatment.
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9.2.2.3 Short-Term Effectiveness
9.2.2.3.1 Landfill Solids. The No Further Action alternative (LFS-2) would provide the
greatest short-term effectiveness because it poses no adverse short-term effects to
workers, the community, or the environment. Construction and implementation risks
associated with placing the additional 2 feet of cover on the north face in Modified
Alternative LFS-4 and regrading in Alternative LFS- 7 would be similar to typical landfill
grading activities. These portions of the alternatives are considered to have a high level
of short-term effectiveness because they have very few adverse effects. There would be a
limited potential for construction workers or the community to be exposed to volatile
organic compounds through the excavation activities associated with Alternatives LFS-3,
LFS-4, and LFS-6, and for the general public to be exposed during offsite transport of
the excavated materials. Modified Alternative LFS-4 would pose a slightly higher risk to
construction workers because of the more extensive level of excavation and thus is
considered to have slightly less short-term effectiveness.
9.2.2.3.2 Landfill Gas. Modified Alternative LFG-3 and Alternative LFG-3 (Stage 1)
would be most effective in the short-term. These alternatives would achieve
protectiveness in a short time frame and would pose minimal short-term risks to workers,
the community, or the environment during construction. Modified Alternative LFG-5
(Stage 1) would be slightly less effective in the short-term because it would pose slightly
greater risks to workers during the installation and operation of heat recovery equipment.
Although the No Further Action alternative (LFG-2) would pose no adverse short-tenn
risks to workers, the community, or the environment from construction activities (because
there would be none), this alternative would not eliminate potential short-term risks from
gas buildup and migration.
9.2.2.4 Implementability
9.2.2.4.1 Landfill Solids. All of the Landfill Solids alternatives are considered rela-
tively equal in terms of technical and administrative implementability. This is because all
alternatives would use proven technologies that have been successfully implemented at
many other sites. Alternatives LFS-4 and LFS-6 would include the excavation of drums,
drum contents, and contaminated soils using readily available construction equipment.
Modified Alternative LFS-4 would consist of excavation as described in
Alternatives LFS-4 and LFS-6, and would also include excavation of waste pits within the
unsaturated zone. This type of excavation is considered routine construction, could be
conducted by local contractors, and has been implemented at other Superfund sites.
Construction of the north face cover in Modified Alternative LFS-4 and regrading in
Alternative LFS-7 would involve routine landfill construction procedures, and cover
material is readily available onsite.
9.2.2.4.2 Landfill Gas. All of the Landfill Gas Alternatives would be technically and
administratively implementable. Next to Alternative LFG-2, Modified Alternative LFG-3
is considered to be the most implementable alternative because this alternative would use
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proven technology, and the construction of gas extraction wells would be a routine
activity t;hat could be conducted by many local contractors. In addition, constructing
Stages 1 and 2 extraction wells together in Modified Alternative LFG- 3 would be easier
to implement than constructing them separately in Alternative LFG-3 (Stage 2) and
Alternative LFG-5 (Stage 2) since there would be only one mobilization expense and less
monitoring to determine rates and directions of gas migration.
Alternative LFG-5, which includes heat recovery, would be the most technically difficult
to implement because heat recovery from an enclosed flare is not commonly practiced.
9.2.2.5 Cost
9.2.2.5.1 Landfill Solids. Modified Alternative LFS-4 (the Drum RemovallOffsite
Disposal alternative) and Alternative LFS-6 (the Drum Removal/Low-Temperature
Thermal Desorption/Stabilization/Disposal alternative) have the highest present-worth
costs. However, Modified Alternative LFS-4 would remove a larger volume of
contaminated material than Alternatives LFS-4 or LFS-6. In addition, Modified
Alternative LFS-4 includes the cover on the northern slope of the landfill mass.
Alternative LFS-4 (the Drum Removal/Offsite Disposal alternative) is the next most
costly alternative, followed by Alternative LFS-2 (the No Further Action alternative),
Alternative LFS-3 (the Clay Cap alternative), and Alternative LFS-7 (the Landfill Mass
Regrading alternative). The costs for each of the landfill solids alternatives are listed
below:
.
Alternative LFS-7: Landfill Mass
Regrading
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$0
$350,000
$5,380,000
.
Alternative LFS-3: Clay Cap
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth
$670,000
$410,000
$6,970,000
.
Alternative LFS-2: No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$36,000
$470,000
$7,260,000
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.
Alternative LFS-4: Drum Removal!
Offsite Disposal
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$2,400,000
$410,000
$8,700,000
.
Alternative LFS-6: Drum RemovailLow
Temperature Thermal Desorption!
Stabil izationlDisposai
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$5,200,000
$410,000
$11,500,000
.
Modified Alternative LFS-4: Drum
Removal!Offsite Disposal!North Face Cover
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$8,600,000
$316,000
$13,460,000
9.2.2.5.2 Landfill Gas. The estimated present-worth costs for Modified Alterna-
tive LFG-3 are slightly greater than present-worth estimates for Alternative LFG-3
(Stage 1). These are the least costly alternatives that meet the threshold criteria.
Alternative LFG-5 would be the next most costly based on present worth estimates. It is
slightly less than Alternative LFG-3 (Stages 1 & 2). The most expensive alternative is
Stage 3 of Alternative LFG-3. The present-worth costs for the OU3 alternatives are
ranked below. These costs also include estimated capital and O&M costs.
.
Alternative LFG-2: No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$36,000
$59,000
$943,000
.
Alternative LFG-3: Gas Collection!
Enclosed Flare (Stage 1)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$3,200,000
$310,000
$7,970,000
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.
Modified Alternative LFG-3: Gas
ColiectionlEnclosed Flare
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$3,200,000
$340,000
$8,430,000
.
Alternative LFG-5: Gas Collection
with Heat Recovery (Stage 1)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$3,700,000
$313,000
$8,510,000
.
Alternative LFG-3: Gas Collection!
Enclosed Flare (Stages 1 and 2)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$3,600,000
$340,000
$8,830,000
.
Alternative LFG-3: Gas Collection!
Enclosed Flare (Stages 1, 2, and 3)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$5,200,000
$503,000
$12,930,000
The above-referenced cost breakdowns suggest that capital costs for Modified Alternative
LFG-3 are similar to capital costs for Alternative LFG-3, Stage 1. Although Modified
Alternative LFG-3 involves an additional stage of well construction (Stage 2) compared to
Alternative LFG-3, Stage 1, it does not include costs associated with a well abandonment
program. Estimated capital costs for Stage 2 construction are approximately equal to
estimated costs for the well abandonment program. Consequently, Modified Alternative
LFG-3 and Alternative LFG-3, Stage 1 have similar capital costs.
9.2.3 Modifying Criteria
9.2.3.1 State/Support Agency Acceptance
The State of Colorado concurs with EP A on the selection of Modified Alternative LFS-4
and Modified Alternative LFG- 3 for OU s 2&3.
9.2.3.2 Community Acceptance
Community input on the alternatives for remedial action for OUs 2&3 were solicited by
EPA and CDH during the public comment period from September 1, 1993 to
DEN) OO153AB. WPS
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November 29, 1993. Comments received from the community were strongly supportive
of the excavation and treatment of contaminated solids in the former tire pile area. The
community was also generally supportive of the simultaneous implementation of the
Stage 1 and 2 gas extraction measures as a means of controlling gas migration offsite.
However, one commenter encouraged EP A to consider the focus of the gas extraction to
be extraction and removal rather than control of offsite gas migration. The commenter
felt that the additional installation of Stage 3 would yield a significant increase in the
annual volume of contaminants removed for a relatively small incremental increase in the
overall cost. The community was also adamantly opposed to the addition of 1.2 million
cubic yards of municipal solid waste over the former waste pits (Alternative LFS-7,
Landfill Regrading). Com mentors were very supportive of EPA's proposal to reject this
alternative.
Comments from the PRPs opposed EPA's preferred alternative and proposed a remedy
consisting of land acquisition and land use restrictions 0.5 mile around the perimeter of
the Lowry Site, the enhancement of the landfill cover through the addition of 1.2 million
cubic yards of municipal solid waste, and the installation of Stage 1 of the gas extraction
system. The PRPs comments also focused on the short-term effectiveness of the
excavation in the former tire pile area and the potential exposure to workers during the
excavation.
Responses to the community and the PRP comments are found in the Responsiveness
Summary for OUs 2&3 in Section 14.0 of this ROD.
9.3 OU 4: Soil and
OU 5: Surface Water and Sediments
9.3.1 Threshold Criteria
9.3.1.1 Overall Protection 0/ Human Health and the Environment
9.3.1.1.1 OU 4: Soils. All of the alternatives for soils are protective of human health
and the environment. This is because the risks to human health and the environment
posed by soil at the Lowry Site are estimated to be minimal and in the range of back-
ground risks. Background risks were found to already be within EP A's acceptable risk
range. The No Further Action alternative (SOIL-I) would be the most protective because
it would not entail any disturbance of soils, thereby minimizing the potential for
exposure. The remaining alternatives (SOIL-2, SOIL-4a, and SOIL-4b) would involve
soil disturbance during construction or excavation which could potentially uncover
material of greater risk. Moveover, the disturbance of the soil would result in an
exposure pathway to construction workers.
9.3.1.1.2 OU 5: Surface Water. The No Further Action alternative (SW-l) is protec-
tive of human health and the environment because the Surface Water Removal Action
DENIOO153AB.WP5
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(SWRA) isolates and treats, to protective levels, contaminated seepage that previously
existed as surface water flow in the unnamed creek. No other alternatives were evaluated
for surface water because the SWRA can be fully integrated into the sitewide remedy.
9.3.1.1.3 OU 5: Sediments. All alternatives considered for sediments in both Sec-
tions 6 and 31 would be protective of human health and the environment.
Sediments in Section 6 have already been covered by a geotextile and low-permeability
soil cap as part of the SWRA. Therefore, there is no exposure to Section 6 sediments
and no current or future risk to human health and the environment. Alternative SED6-2
would be slightly more protective of human health and the environment because the
exposure pathway posed by sediments in Section 6 would be further limited through a
physical barrier (fence).
For Section 31 sediments, the Baseline Risk Assessment found that risks associated with
potential sediment contaminant exposures were within the acceptable excess cancer risk
range. Therefore, Alternative SED3l-1 (the No Further Action alternative) would be
protective of human health and environment. Alternatives SED31-2 and SED3l-3 are
considered to be the most protective because they would eliminate exposure, although
there would be an increased potential for short-term exposure to sediments from the
disturbance of sediments.
9.3.1.2 Compliance with ARARs
The ARARs for ODs 4&5 alternatives are discussed in Section 8.0.
9.3.1.2.1 OU 4: Soils. All alternatives would meet ARARs. The requirements primar-
ily deal with landfilling and maintenance actions and would be met by following the
requirements of the regulations.
9.3.1.2.2 OU 5: Surface Water. The only alternative evaluated, No Further Action,
would meet ARARs.
9.3.1.2.3 OU 5: Sediments. All alternatives for both Section 6 and Section 31 sedi-
ments would meet ARARs. The ARARs primarily deal with construction, excavation,
and landfilling actions and would be met by satisfying the requirements of each
regulation.
9.3.2 Primary Balancing Criteria
9.3.2.1 Long-Tenn Effectiveness and Pennanence
9.3.2.1.1 ?U 4: Soils. Alternatives SOIL-4a, and SOIL-4b (Excavation and Landfill)
would ~roVlde the greatest long-term effectiveness and permanence because these
alternatives would require excavation and landfilling of contaminated materials.
DEN 1001 S3AB.WP5
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Alternative SOIL-2 (Access Restrictions and Dust Control) would provide the next
greatest long-term effectiveness and permanence because the soil would be covered by
vegetation and exposure to the soil would be further restricted by a fence. The No
Further Action alternative would provide the next level of long-term effectiveness and
permanence through institutional controls. The risks associated with the No Further
Action alternative are within EPA's acceptable risk range. Therefore, the No Further
Action alternative would offer acceptable long-term effectiveness and permanence.
9.3.2.1.2 OU 5: Surface Water. The SWRA has been constructed, has operated
reliably, and has met performance standards. The SWRA has been designed for long-
term operation and will be monitored and maintained such that it continues to achieve
performance standards. Thus, the SWRA will provide long-term effectiveness and
permanence.
9.3.2.1.3 OU 5: Sediments. In Section 6, the sediments have already been covered as
part of the SWRA. Alternative SED6-2 (Access Restrictions) would provide the greatest
long-term effectiveness and permanence by fencing the cover over the sediments to
restrict access and by maintaining the cover. Alternative SED6-l (No Further Action)
would provide nearly as great long-term effectiveness and permanence through continued
maintenance of the cover.
Alternative SED3l-3 (the Excavation and Landfill alternative) would provide the greatest
long-term effectiveness and permanence through removal and landfilling of the sediments.
Alternative SED3l-2 (the Access Restriction/Capping alternative) would provide the next
level of long-term effectiveness and permanence by minimizing the exposure to the
sediments through physical barriers (a cap and fence). Alternative SED31-l (No Further
Action) would provide acceptable long-term effectiveness and permanence because the
risks associated with the sediments are within EPA's acceptable risk range.
9.3.2.2 Reduction of Toxicity, Mobility, or Volume Through Treatment
9.3.2.2.1 OU 4: Soils. None of the soils alternatives involve treatment. Therefore,
these alternatives would not result in a reduction of toxicity, mobility, or volume through
treatment.
9.3.2.2.2 OU 5: Surface Water. Under the No Further Action alternative, the SWRA
would reduce the volume of contaminants through collection and treatment of the alluvial
seepage. In the absence of the SWRA, this seepage would have become contaminated
surface water by emerging in the unnamed creek drainage. There would be no apparent
reduction in the toxicity or mobility of the contaminants since the treatment would not
induce any changes in the chemical forms; however, the contaminants would be
immobilized/adsorbed using granular activated carbon during treatment.
9.3.2.2.3 OU 5: Sediments. None of the sediments alternatives for Section 6 or 31
would involve treatment. Therefore, these alternatives would not result in a reduction of
DENl00lS3AB.WP5
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toxiCity, mobility, or volume through treatment. However, the mobility of the
contaminants would be reduced in Alternatives SED3l-2 and SED3l-3 through
engineering controls.
9.3.2.3 Short-Term Effectiveness
9.3.2.3.1 OU 4: Soils. The No Further Action alternative (SOIL-I) would not involve
soil disturbance and, therefore, would provide maximum short-term protection to workers
and the community. The risk from soils are already within EPA's acceptable risk range
and therefore the time until protection is achieved is immediate.
Alternative SOIL-2 would provide the next greatest short-term protection to workers, the
environment, and the community because it involves only access restrictions and dust
control activities.
Alternatives SOIL-4a and SOIL-4b would involve disturbance in the short-term through
excavation of soils. This would result in a potential for exposure to workers and
disturbance of existing habitats.
9.3.2.3.2 OU 5: Suiface Water. Construction and startup of SWRA facilities have
been completed and were conducted in a manner without accidents or adverse environ-
mental impacts. Therefore, the SWRA satisfies the short-term effectiveness criterion.
9.3.2.3.3 OU 5: Sediments. Alternatives SED6-l (No Further Action) and SED31-1
(No Further Action) provide the greatest short-term effectiveness for workers, the
community, and the environment because these alternatives require no disturbance of
sediments. Alternative SED6-2 requires installation of fencing, which would involve
minimal exposure to workers and habitat disturbance. Alternatives SED31-2 and SED31-
3 would involve sediment disturbance through capping and/or excavation activities.
Therefore, these alternatives would be the least effective in providing short-term
protection.
9.3.2.4 Implementability
9.3.2.4.1 OU 4: Soils. All alternatives are considered to be technically and administra-
tively implementable. Alternatives SOIL-2, SOIL-4a (Option 1), SOIL-4b (Option 1),
and the No Further Action alternative would be equally implementable. Option 2 of
Alternatives SOIL-4a and SOIL-4b would be harder to implement because of technical
difficulties associated with the one-time excavation of approximately 2.5 million cubic
yards of soil, uncertainties about availability of land for stockpiling, and difficulties
associated with maintenance of the stockpile.
9.3.2.4.2 OU 5: Suiface Water. The SWRA has been constructed and is operational,
and is therefore implementable.
DENlOOI53AB.WP5
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9.3.2.4.3 OU 5: Sediments. Implementation of Alternative SED6-1 (No Further Action
alternative) and Alternative SED6-2 (Access Restrictions) would be technically feasible
because of the availability of materials for access control and for fugitive dust and noise
control. Except for additional fencing, Alternative SED6-2 (Access Restrictions) is
already an integral part of the SWRA.
Alternative SED31-1 (No Further Action) and Alternative SED3l-2 (Access Restrictions
and Capping) would both be technically implementable. Alternative SED31-3
(Excavation and Landfill) would also be implementable; however, some seasonal delays
could be encountered when implementing this alternative because of a potential need for
wetlands construction.
9.3.2.5 Cost
9.3.2.5.1 OU 4: Soils. Excavation alternatives generally have the highest present-worth
costs. Alternative SOIL-4b (Option 2) is the most expensive because of the magnitude of
excavation, materials movement, and offsite stockpiling. The No Further Action
alternative and Alternative SOIL-4a (Option 1) would be the least expensive alternatives.
Present-worth costs for OU 4 are ranked below. These costs include estimated capital
and O&M costs.
.
Alternative SOIL-I: No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$22,000
$24,000
$390,000
.
Alternative SOIL-4a, Option 1:
Excavation (as-needed) and Landfill
(onsite)
Capital Costs:
Annual O&M Costs:
Total (3D-year Present Worth):
$43,000
$29,000
$490,000
.
Alternative SOIL 4b, Option 1:
Excavation (as-needed) and Landfill
(off site)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$1,200,000
$44,000
$1,880,000
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.
Alternative SOIL-2: Access Restrictions
and Dust Control
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$1,400,000
$44,000
$2,080,000
.
Alternative SOIL 4a, Option 2:
Excavation (one-time) and Landfill
(onsite)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$2,800,000
$31,000
$3,280,000
.
Alternative SOIL 4b, Option 2:
Excavation (one-time) and Landfill
(offsite)
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$4,000,000
$52,000
$4,800,000
9.3.2.5.2 OU 5: Surface Water. Capital costs for construction of the SWRA have
already been incurred and are not included in the cost estimate. Other costs associated
with the No Further Action alternative (SW -1) would include O&M for the SWRA and
the construction of wetlands. These costs are as follows:
.
Alternative SW-l, No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$41,000
$790,000
$12,190,000
9.3.2.5.3 OU 5: Sediments. Access Restrictions/Capping (Alternative SED31-2) and
Excavation and Landf1l1 (Alternative SED3l-3) would be the most costly alternatives.
The No Further Action alternatives (SED6-1 and SED31-1) would be the least expensive
alternatives. Present-worth costs for sediments alternatives are ranked below. These
costs include estimated capital and O&M costs.
.
Section 6 Sediments Alternative
SED6-1: No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$16,000
$15,000
$250,000
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.
Section 6 Sediments Alternative
SED6-2: Access Restrictions
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$93,000
$23,000
$450,000
.
Section 31 Sediments Alternative
SED31-1: No Further Action
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$22,000
$18,000
$300,000
.
Section 31 Sediments Alternative
SED31-2: Access Restrictions and Capping
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$400,000
$53,000
$1,215,000
.
Section 31 Sediments Alternative
SED31-3: Excavation and Landfill
Capital Costs:
Annual O&M Costs:
Total (30-year Present Worth):
$620,000
$40,000
$1,235,000
9.3.3 Modifying Criteria
9.3.3.1 State/Support Agency Acceptance
The State of Colorado concurs with the EP A on the selection of the No Further Action
alternative for OUs 4&5.
9.3.3.2 Community Acceptance
Community input on the alternatives for remedial action for au s 4&5 was solicited by
EPA and CDH during the public comment period from September 1, 1993, to
November 29, 1993. Comments received from the community and the PRPs indicate no
opposition to the preferred alternative for each media under OUs 4&5. Responses to
community comments are found in the Responsiveness Summary in this ROD.
DENlOO153AB.WPS
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Section 10.0
Documentation of Significant Changes
-------
Section 10.0
Documentation of Significant Changes
Two separate Proposed Plans were published by EP A and released for the Lowry Site.
One Proposed Plan was for the Shallow Ground Water and Subsurface Liquids/Deep
Ground Water Operable Units (OUs 1&6), and that document was released for public
comment in November 1992. The second Proposed Plan for the Landfill Solids/Gas
Operable Units and for the Soils/Surface Water and Sediments Operable Units (OUs 2&3
and 4&5) was released for public comment in August 1993. The second Proposed Plan
also included a description of the proposed sitewide remedy that addressed all six OUs.
The Proposed Plan for OUs 1&6 identified Modified Alternative GW-5 (the North
Boundary/Toe of Landfill/Lateral and Upgradient Containment, Collection, and Treat-
ment alternative) as the preferred alternative for ground-water and subsurface liquids
remediation. EP A reviewed all written and verbal comments submitted during the public
comment period, and issued a preliminary response in August 1993.
The OUs 2&3 and 4&5 Proposed Plan identified Modified Alternative LFS-4 (the Drum
Removal/Offsite Disposal/North Face Cover alternative) as the preferred alternative for
landfill solids and Modified Alternative LFG-3 (the Gas Collection/Enclosed Flare
alternative) as the preferred alternative for landfill gas. For soils, surface water, and
sediments, the OUs 2&3 and 4&5 Proposed Plan identified the No Further Action
alternative as the preferred alternative. The OU s 2&3 and 4&5 Proposed Plan also
described how all of the preferred alternatives would be integrated into a sitewide
remedy. The sitewide remedy is the combination of the preferred alternatives for each
OU.
There are no significant changes from the proposed plans. However, the present worth
cost calculations, as they appear in the ROD, differ slightly from those presented in the
proposed plans. In order to allow for the consistent comparison of costs for the various
alternatives, EPA recalculated the costs using a single set of assumptions. The following
factors were standardized for all components of the selected sitewide remedy: indirect
costs; capital costs contingencies; interest rates; and inflation rates.
DENlOO153AC.WP5
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Section 11.0
Selected Sitewide Remedy
-------
Section 11.0
Selected Sitewide Remedy
After considering CERCLA's statutory requirements, the detailed analysis of the
alternatives using the nine criteria, and public comments, EPA, in consultation with
CDH, has determined that the most appropriate sitewide remedy for the Lowry Site
includes the following OU components, described in greater detail in Subsections 11.2
through 11.5 of this ROD:
.
OUs 1&6-Shallow Ground Water and Subsurface Liquids and Deep
Ground Water-Modified Alternative GW-5 (the North Boundary, Toe of
Landfill, and Lateral [Eastern and Western] Containment, Collection and
Treatment plus Upgradient Containment, Collection and Diversion
alternative).
.
OU 2- Landiill Solids- Modified Alternative LFS-4 (the Drum Removal!
Off site Disposal/North Face Cover alternative).
.
OU 3- Landiill Gas-Modified Alternative LFG-3 (the Gas Collection/
Enclosed Flare alternative).
.
OU 4&S-Soils, Surface Water, and Sediments-No Further Action
alternative.
The selected sitewide remedy also includes the general components described in
Subsection 11.1 of this ROD. The selected sitewide remedy addresses all contaminated
media at the Lowry Site and provides the best balance of tradeoffs among the nine
criteria. EP A has also determined that the selected sitewide remedy is protective of
human health and the environment. Although the selected sitewide remedy includes
containment elements, the selected sitewide remedy also includes significant collection
and treatment elements. Figure 11-1 is a graphical representation of the selected sitewide
remedy. Table 11-1 presents the ARARs for the selected sitewide remedy. Additional
performance standards for the selected remedy are described in the following subsections.
11.1 General Components of the
Selected Sitewide Remedy
The selected sitewide remedy includes the following general components:
Institutional Controls- Institutional controls are nonengineering methods
by which Federal, State, local governments, or private parties can prevent
or limit access to or use of a site. Institutional controls for the Lowry Site
shall include, but not be limited to, deed notices and restrictions that run
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11-1
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DENlOO153AD.WP5
with the land; on site access restrictions including, but not limited to,
fencing and warning signs; zoning controls; and well restrictions.
Executive Order No. 97, as issued by City and County of Denver Mayor
Federico Peiia, currently provides some measure of control. Institutional
controls at the Lowry Site must prohibit all activities and uses that EP A
determines would interfere or be incompatible with, or that would in any
way reduce or impair the effectiveness or protectiveness of, the sitewide
remedy. These shall include, but are not limited to, prohibitions on all
ground-water well construction and use not necessary for implementation
and monitoring of the selected remedy; prohibitions on access; and
prohibitions on activities and land use not connected with design,
construction, and implementation and monitoring of the selected sitewide
remedy.
Offsite institutional controls shall serve as an additional measure of
protection to enhance the effectiveness of the selected remedy and to act as
preventative measures to preserve the implementability and effectiveness of
any of the selected remedy contingency measures. Offsite institutional
controls shall include, but not be limited to, deed notices and restrictions,
zoning controls, and well restrictions. These controls must prohibit all
offsite activities in the vicinity of the Lowry Site that would interfere or be
incompatible with, or that would in any way reduce or impair the
effectiveness or protectiveness of, the selected sitewide remedy.
All onsite and off site institutional controls shall be adequately administered,
maintained, and enforced.
The owner and operator of the Lowry Site shall be responsible for access
restrictions, warning signs, and fences.
.
Performance and Compliance Monitoring-To ensure that the
performance standards are met for all components of the selected remedy
for as long as contamination remains onsite, a long-term monitoring
program shall be designed and implemented during the RD/RA and shall
continue throughout the implementation of the selected sitewide remedy.
The monitoring program shall assess compliance with the remediation
levels in the ground-water system, monitor effluent chemical concentrations
from the treatment plant, evaluate the horizontal and vertical migration of
contamination, monitor the erosion of soils and sediments and monitor the
,
migration of landfIll gases. Details of the monitoring program shall be
determined by EPA, in consultation with CDH, during the RD. The
monitoring program shall include, at a minimum, the following: analytical
parameters and methods; indicator parameters; monitoring locations;
mo~toring frequency and duration; sampling methods; well installation,
mamtenance and abandonment procedures; statistical methods for
evaluating data; reporting methods and procedures for tracking and
11-2
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maintaining sample records; and QA methods, including data validation
methods. It is estimated that approximately 60 to 100 ground-water
monitoring wells will be sampled semi-annually. Landfill gas shall be
monitored quarterly, or more frequently if migration is detected, using
approximately 40 to 60 monitoring wells. The ground-water monitoring
component of the selected sitewide remedy includes an early-warning
monitoring component; this will allow for a timely remedial response in the
event that EP A determines that additional remedial actions are necessary.
Soil and sediment erosion shall be monitored on a monthly basis using
three surface-water samplers installed in drainages. The actual details of
the monitoring program are subject to revisions and refinement during RD.
.
Five--Year Review-As specified in Section 121(c) of CERCLA, as
amended by SARA, and Section 300.430(f)(4)(ii) of the NCP, EPA will
review the sitewide remedy no less often than each 5 years after the
initiation of the remedial action to assure that human health and the
environment are being protected by the implemented remedy (this review
will ensure that the remedy is operating and functioning as designed and
that institutional controls are in place and are protective). An additional
purpose for the review is to evaluate whether the performance standards
specified in this ROD remain protective of human health and the
environment. EP A will continue the reviews until no hazardous
substances, pollutants, or contaminants remain at the Lowry Site above
levels that allow for unrestricted use and unlimited exposure.
11.2 Remedy for Shallow Ground Water
and Subsurface Liquids and Deep Ground Water
The selected remedy for shallow ground water and subsurface liquids and deep ground
water (ground-water remedy) shall contain, collect, and treat contaminated shallow
ground water at the Lowry Site. This shall be achieved through the construction and
operation of barrier walls, collection and diversion systems, and a treatment system to be
upgraded as necessary, and continued operation of the existing barrier wall and collection
system, thereby reducing the mobility of potential contamination from the main source
and reducing the level of toxicity and volume of contamination. Specifically, the ground-
water remedy shall include the following containment and treatment components:
DENIOOIS3AD.WP5
.
Evaluation of the effectiveness of, and upgrading as necessary, the barrier
wall system at the northern boundary of the Lowry Site to restrict offsite
migration of contaminated ground water.
.
Installation and operation of a ground-water extraction system at the toe of
the former landfill. This ground water will be pumped to the ground-water
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treatment plant. The treatment plant will be upgraded as necessary to meet
performance standards, as described below.
.
Construction and operation of underground barrier walls and ground-water
collection systems on the west and east sides of the Lowry Site.
.
Construction and operation of an approximately 50-foot-deep upgradient
ground-water containment, collection, and diversion system along the
southern perimeter of the Lowry Site.
.
Design and construction of a new ground-water treatment plant unless it
can be demonstrated through pilot-scale testing during the RD that the
existing ground-water treatment plant can effectively treat the more highly
contaminated ground water to the performance standards.
.
Annual interception and treatment of approximately 6.4 million gallons of
contaminated ground water from the barrier walls and collection systems.
.
Implementation of a long-term ground-water monitoring program for
assessing compliance with performance standards and protectiveness of the
remedy for the shallow ground-water system and potential impacts on deep
ground water.
.
Implementation of a contingency measure (see Subsection 11.2.1.2) if
contaminant migration (including NAPLs movement) into deep ground
water occurs in the future. EP A's decision regarding the contingency
measure will be based on an evaluation of monitoring data and comparison
with performance standards as described in Table 11-2.
The ground-water remedy also includes components of the selected remedies for ODs
2&3 and ODs 4&5. Applicable components include:
DEN! OO153AD.WPS
.
Maintenance of the existing cover on the landfill mass (described in
Subsection 11.3).
.
As modified by this ROD, continued operation of the Surface Water
Removal Action (SWRA), including the upgraded treatment plant and
collection system within unnamed creek. The Surface Water Removal
Action also includes continued operation, maintenance, and monitoring of
the existing ground-water barrier wall at the northern boundary of the
Lowry Site. Transition from the SWRA performance standards to the
ground-water remedy performance standards is described in Subsection
11.2.2.1.
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The ground-water remedy shall achieve the Remedial Action Objectives (RAOs) for the
protection of human health and the environment. The RAOs for the ground-water
remedy are:
.
Prevention of exposure to humans and the environment (through ingestion,
inhalation, or dermal absorption) from liquids (either ground water or
waste-pit liquids) containing contaminants in excess of the performance
standards
.
Prevention of migration of contaminants beyond the compliance boundary
in excess of the performance standards
.
Prevention of horizontal migration of dissolved ground-water contaminants
off site and to surface waters
.
Prevention of vertical migration of dissolved ground-water contaminants
beyond the lignite layer
.
Prevention of movement of nonaqueous phase liquids (NAPLs) beyond the
compliance boundary and minimization of movement of NAPLs
.
Minimization of inf1ltration and leachate production in the waste-pit source
area
11.2.1 Containment Components (Barrier Walls and Collection Systems)
The containment components of the ground-water remedy shall effectively isolate the
contamination at the Lowry Site from the surrounding areas by controlling horizontal
migration of contaminated ground water through the construction of containment and
diversion systems. The construction and operation of these systems shall comply fully
with all ARARs as described in Table 11-1. The requirements of the Colorado
Hazardous Waste Act and Land Disposal Restrictions of the Solid Waste Act shall be met
through testing and proper disposal if RCRA hazardous waste, hazardous waste
sufficiently similar to RCRA hazardous waste, or solid waste is generated during
construction. Air emissions shall be monitored to ensure compliance with the Colorado
Air Quality ActJ Air Pollution Regulations. All monitoring wells shall be constructed and
abandoned according to the requirements of the Well Construction and Abandonment
Procedures of the State Engineer's Office to ensure that a migration pathway is not
created.
The following discussion provides a detailed description of each containment component.
Figure 11-1 illustrates the approximate locations and relative length of each containment
component.
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11-5
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Northern Boundary. Containment shall be accomplished using the existing barrier wall,
elongating the existing barrier wall, or constructing a barrier wall immediately upgradient
or downgradient of the existing barrier wall that may be deeper and longer than the
existing barrier wall. The effectiveness of the existing barrier wall and the need for a
modified barrier wall or new barrier wall shall be evaluated during the RD. EP A shall
determine whether a modified or new barrier wall is needed, based on an evaluation of
whether the existing system is able to meet performance standards. The protectiveness of
this component of the selected remedy shall be ensured on the northern boundary by the
implementation of monitoring systems at the compliance boundary and at the Point of
Action boundary (installation of an early warning monitoring well network).
Toe of the Landiill. A ground-water extraction system shall be installed and operated at
the toe of the landfill to capture contaminated shallow ground water migrating from the
landfill mass at the Lowry Site and prevent further contamination of the aquifer
downgradient of the landfill mass. The dimensions of the subsurface drain shall be such
that the drain will intercept and collect the contaminated ground water within the shallow
ground-water system at the toe of the landfill mass. Approximate dimensions are 300
feet long and 50 feet deep, but actual dimensions shall be determined by EP A, in
consultation with CDH, during RD.
Eastern and Western Boundaries. Underground barrier walls and ground-water
collection systems shall be constructed and operated on the east and west sides of the
Lowry Site so as to prevent potential offsite migration of contaminated shallow ground
water. The dimensions of the systems shall be such that the collection systems will
intercept and collect the contaminated ground water within the sand channels within the
shallow ground-water aquifer. Approximate dimensions are 2,000 feet long by 50 feet
deep on the eastern boundary and 1,000 feet long by 50 feet deep on the western
boundary. Actual dimensions shall be determined by EP A, in consultation with CDH,
during RD. The protectiveness of these components of the selected remedy shall be
ensured on the eastern and western boundaries by the implementation of monitoring
systems at the compliance boundary and at the Point of Action boundary (installation of
an early warning monitoring well network).
Southern Perimeter. An approximately 50-foot-deep upgradient ground-water
containment, collection, and diversion system (barrier wall) shall be constructed and
operated along the southern perimeter of the Lowry Site so as to prevent offsite
contaminant migration to the south and recharge of ground water from the south. The
barrier wall shall be installed in the saturated portion of the weathered zone. The
approximate dimensions of the barrier wall are 1,500 feet long, 50 feet deep, and 3 feet
wide. Upgradient extraction wells shall also be installed to collect uncontaminated
upgradient ground water for diversion around the Lowry Site. The actual dimensions of
the barrier wall system and configuration of the uprgradient extraction wells shall be
determined by EPA, in consultation with CDH, during RD. The protectiveness of this
~mponent of the selected remedy shall be ensured on the southern boundary by the
Implementation of monitoring systems at the compliance boundary and at the Point of
Action boundary (installation of an early warning monitoring well network).
DENlOOlS3AD.WPS
11-6
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11.2.1.1 Perfonnance Standards and Points of Compliance
The containment components of the ground-water remedy shall meet the performance
standards, which are presented in Tables 11-1 and 11-2. Table 11-1 includes all ARARs
for the selected remedy, including the ground-water portion of the remedy. Table 11-2
presents chemical-specific numeric standards for the ground-water remedy, some of
which are based on ARARs. Table 11-2 performance standards shall be met at the
ground-water compliance boundary.
The compliance boundary is depicted in Figure 11-2. The compliance boundary for
vertical ground-water migration is the lignite layer. The ground water within the
compliance boundary is not expected to be restored to meet the performance standards
because the sitewide remedy consists of containment and the source areas will remain in
place.
In locating the point of compliance for ground-water performance standards, EP A has
determined that performance standards shall be attained at and beyond the edge of the
waste management area when waste is left in place. At the Lowry Site, the plume of
ground-water contamination is caused by releases from several distinct sources that are in
close geographical proximity. In addition to the delineated locations of the waste pits and
landfill mass, historical evidence indicates that the northwestern, northern, northeastern,
and eastern areas of the Lowry Site received waste via sludge application, leachate
injection, and leachate spraying. Consequently, the most feasible and effective ground-
water cleanup strategy is to draw the point of compliance to encompass the sources of
release and thereby address ground-water contamination as a whole. In establishing the
ground-water compliance boundary, EP A considered the proximity of the sources, the
technical practicability of ground-water remediation, the vulnerability of the ground water
and its possible uses, and the likelihood of exposure.
The selected ground-water remedy also includes a Point of Action (POA) boundary
(Figure 11-2). Table 11-3 identifies numeric standards for the POA boundary which are
based on the Colorado Basic Standards for Ground Water [5 CCR-l002-8 (3. 11.5c)].
The POA boundary encompasses the highly concentrated waste-pit liquids and ground
water within the main source area and unnamed creek. Ground-water monitoring shall be
conducted at the POA boundary and additional measures, as described in the next section,
shall be taken if Table 11-3 standards are exceeded at the POA boundary. The POA
boundary has been established to provide sufficient warning such that response actions
can be taken to prevent violation of performance standards at the compliance boundary.
The physica1lsurveyed location of the compliance boundary and the POA boundary shall
be determined by EP A during RD.
To ensure compliance of the ground-water containment components with the RAOs and
performance standards, the barrier walls and collection systems shall be monitored. The
monitoring systems shall consist of wells upgradient, downgradient, and adjacent to the
barrier walls. The well placement shall be such that the hydraulic gradient information
DENlOOlS3AD.WP5
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from the wells demonstrates the containment systems' effectiveness. Additionally,
contaminant concentrations shall be measured to determine whether the containment
systems capture the ground water and prevent contamination downgradient and adjacent
to the systems. Details of the monitoring program shall be determined by EPA, in
consultation with CDH, during the RD.
11.2.1.2 Contingency Measures
If, during implementation or operation of the ground-water remedy, contaminant levels
exceed the performance standards at the POA or compliance boundaries, appropriate
measures shall be taken to prevent and remediate contaminant migration beyond the
compliance boundary. Such measures may include but are not limited to any or all of the
following, subject to approval by EPA:
.
Alternating pumping at wells to eliminate stagnation points
.
Pulse pumping to allow aquifer equilibration and to allow adsorbed
contaminants to partition into ground water
.
Installation of additional extraction wells to facilitate containment of the
contaminant plume, to address possible vertical migration of contaminants,
and if necessary to remediate the ground water to performance standards.
To ensure that performance standards continue to be met and maintained, the aquifer
shall be monitored at appropriate locations and frequencies, as determined by EP A.
If EP A determines, on the basis of monitoring data, that contaminants have migrated
vertically downward to the lignite layer, contingency measures shall be implemented to
ensure that performance standards are achieved and maintained and to ensure that the
beneficial use of the underlying aquifer is not impaired. Contingency measures may
include any or all of the following, at EPA's discretion, for an indefinite period of time,
as a modification of the existing system:
.
Additional engineering controls such as underground barriers, or long-term
gradient control provided by low level pumping, as containment measures
Continued monitoring of specified wells
.
.
Periodic re-evaluation of remedial technologies for ground-water
restoration
.
Additional institutional controls on water extraction and use
DENIOOIS3AD.WPS
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11.2.2 Treatment Component
The ground-water remedy shall treat approximately 6.4 million gallons of contaminated
ground water annually, collected from the new and existing collection systems and barrier
walls. A new on site treatment plant shall be designed and constructed unless it can be
demonstrated through pilot-testing that the existing plant can be upgraded to effectively
treat the more highly contaminated ground water from the toe of the landfill to
performance standards. Based on treatability studies of the influent from the toe of the
landfill conducted during the OUs 1&6 RI, the following treatment technologies have
been determined to be effective in treating highly contaminated ground water and may be
used to treat the contaminated ground water collected from the Lowry Site: gravity-phase
separation for nonaqueous phase liquids (NAPLs); lime soda softening for metals,
radionuclides, hardness, and solids; and biological treatment (pACT) to remove organic
compounds, BOD, COD, ammonia, and nitrate. Treatment technologies shall be
evaluated further during RD; actual selection of treatment technologies shall be subject to
EP A approval, in consultation with CDH.
Air emissions from the treatment plant shall be treated using vapor-phase activated carbon
and monitored to ensure that performance standards, including the Colorado Air Quality
ActJAir Pollution Regulations are met. During construction and operation, noise levels
will be monitored to ensure that the Colorado Noise Abatement Statute will be met.
11.2.2.1 Performance Standards and Points of Compliance
The ground-water treatment plant shall meet water and air quality performance standards
presented in Tables 11-2 and 11-5 of this ROD, respectively, no later than 60 days after
the startup of a new or upgraded ground-water treatment plant, or no later than 60 days
after a determination by EP A that the existing treatment plant may be used without an
upgrade. These performance standards shall supersede the performance standards
identified in the SWRA Consent Order. However, until that time, the performance
standards identified in the SWRA Consent Order shall remain in effect. The point of
compliance for the ground-water treatment plant effluent shall be existing Port 13 of the
treatment pIant or its equivalent in the upgraded or new treatment plant.
Table 11-4 identifies performance standards for surface water. While a surface water
discharge from the ground-water treatment plant is not anticipated, there is a possibility
that the ground-water injection trench could malfunction and allow water to surface. Any
such surface water discharge shall meet the performance standards in Table 11-4.
Construction, operation, and maintenance of the ground-water treatment plant shall
comply with the performance standards (ARARs) specified in Table 11-1.
Residuals from the treatment process will include spent vapor-phase granular activated
carbon, solids from lime-soda softening, and PACJ'fM solids. Spent carbon shall be
transported and regenerated off site in accordance with the performance standards
DENlOO153AD.WP5
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(ARARs) identified in Table 11-1 and in compliance with EPA's off site policy. Other
residuals spall be transported and disposed in accordance with the performance standards
(ARARs) identified in Table 11-1 and EPA's offsite policy.
Monitoring pursuant to a plan approved by EPA shall be conducted to ensure that
performance standards are met.
11.2.2.2 Contingency Measures
The treatability studies conducted during the ODs 1&6 RI indicated that there may be
difficulty in achieving the performance standards for certain metals and methylene
chloride and other similar organics. If performance standards for metals cannot be met
by the existing ground-water treatment plant, additional metal treatment processes shall be
installed to ensure compliance with the performance standards. Additionally, if
performance standards for any organics, including, but not limited to, methylene
chloride, cannot be met by the treatment plant, additional treatment technologies shall be
installed to ensure compliance with the performance standards.
11.3 Remedy for Landfill Solids
The selected remedy for landfill solids is containment for the landfill mass and removal
of accessible solids in the former tire pile area and shall be achieved through the
following activities:
.
Maintenance of the existing cover on the landfill mass
.
Placement of an additional 2-foot cover on the north face of the landfill
mass
.
Excavation, removal, and treatment, within the former tire pile area, of
surface and subsurface drums, contaminated soils, and waste pits and
reclamation of the former tire pile area
The solids remedy shall achieve the following landfill solids RAOs:
.
Protection of human health and the environment from direct contact or
ingestion of landfill solids or soils intermingled with landfill solids
containing contaminants
.
Protection of humans from inhalation of volatilized contaminants from
landfill solids or soils intermingled with landfill solids, and inhalation of
contaminated airborne particulate matter from soils or landfill solids that
exceed performance standards
DENlOO153AD.WP5
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.
Minimization of the production and migration of leachate, from landfill
solids or soils intermingled with landfill solids, to the saturated zone and
ground water
.
Minimization of the migration of soils intermingled with solids, caused by
erosion or entrainment by wind or water
.
Prevention of offsite migration of landfill solids and soils intermingled with
solids into other media
.
Protection of human health and the environment from direct contact with or
ingestion of leachate that exceeds the performance standards for shallow
ground water and subsurface liquids
.
Prevention of offsite migration of leachate or infiltration into other media
Maintenance of the existing cover on the landfill mass and the addition of a 2-foot cover
on the north face of the landfill mass shall reduce risk by minimizing (1) the potential for
contact with contamination from landfill solids, and (2) infiltration, thus reducing
additional ground-water contamination. Details of operation and maintenance measures
for the existing cover and the new north face cover shall be refined during RD and shall
be subject to EP A approval, in consultation with CDH.
11.3.1 Performance Standards and Points of Compliance
Excavation activities in the former tire pile area shall remove surface and subsurface
drums, associated free liquids, and other visible contamination to the extent practicable.
This shall include excavation of contaminated materials and soils in waste pits in the
former tire pile area. It is estimated there are approximately 10 surface and 1,350 buried
drums containing approximately 1,300 gallons of liquid waste, and that there are
approximately 15,000 cubic yards of contaminated soil and debris in the area. The actual
numbers may be different. "Visible" contamination shall include stained or discolored
materials such as soil, construction debris, woody materials, and refuse; excavation "to
the extent practicable" shall include the removal of visible contamination until
undisturbed, competent, native bedrock is encountered. These terms, as well as the
overall areal extent of contamination and approach to excavation within the former tire
pile area, will be further defined by EPA, in consultation with CDH, during RD.
Contaminated materials in the former tire pile area shall be excavated and characterized
for offsite treatment and disposal to meet RCRA Subtitle C and D requirements of the
Solid Waste Disposal Act and the Colorado Hazardous Waste Act. In addition,
maintenance of the landfi.ll cap shall comply with the above ARARs. Liquids shall be
treated offsite at a RCRA Subtitle C facility using incineration and ash stabilization, or
other treatment method capable of similar performance approved by EPA, in consultation
with CDH. It is anticipated that solids and soils shall be treated using stabilization before
DENlOOlS3AD.WP5
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disposal, but actual treatment methods shall be determined by EP A, in consultation with
CDH, during RD.
The excavations shall be backfilled with clean soils. To meet the existing grade, a 2-foot-
thick layer of clay soil shall be placed on top of the excavated areas as a cap. The
purpose of the cap shall be to minimize infiltration. The clay shall be placed in lifts not
exceeding 6 inches and compacted to a minimum of 95 percent relative density according
to Standard Proctor (ASTM D698). A minimum 6-inch top soil layer shall be placed on
top of the cap and shall be vegetated with a dryland pasture mix similar to that used on
the main landfill mass to stabilize the cap surface and minimize soil and wind erosion.
The remedy for landfill solids shall comply with all other performance standards
(ARARs) identified in Table 11-1.
11.4 Remedy for Landfill Gas
The selected remedy for landfill gas shall contain, collect, and treat landfill gas to prevent
offsite migration of, and explosion due to, landfill gas. Containment, collection, and
treatment of landfill gas shall be achieved through the construction and installation of
perimeter and interior gas extraction wells and treatment of the gas using an enclosed
flare. Specifically, the selected remedy shall include the following components:
.
Installation of gas collection and monitoring wells on the western, eastern,
and southern perimeter and in the interior of the former landfill
.
Treatment of landfill gas using an enclosed flare
The landfill gas remedy shall achieve the following RAOs for landfill gas:
.
Protection of human health from inhalation of landfill gases in excess of
the performance standards
.
Protection of human health and the environment from explosion hazards
associated with landfill gases
.
Prevention of offsite migration of landfill gas or migration to other media
The installation of gas collection wells on the western, eastern, and southern boundaries,
and in the interior of the former landfill, shall control gas migration. Approximately
21 perimeter collection wells and two interior collection wells shall be installed to
intercept migrating gas. The gas shall be treated at a rate of approximately 2,000 sefm
per day using an enclosed flare with an 8-foot-diameter stack approximately 40 feet in
height. Condensate collected in the gas collection system shall be treated in the ground-
water treatment plant. The actual number and location of wells, rate of treatment, and
DENlOO153AD.WP5
11-12
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size of the enclosed flare, may change as a result of RD, subject to EPA approval, in
consultation with CDH.
Approximately 26 gas monitoring probes shall also be installed along the perimeter of the
Lowry Site to improve the perimeter gas monitoring system. The actual number may
change as a result of RD, subject to EPA approval, in consultation with CDH. Samples
collected from the gas monitoring probes shall be analyzed for methane and VOCs, which
shall act as indicators for the effectiveness of the collection system. EP A will evaluate
existing gas, waste-pit liquid, and ground-water monitoring wells within the former
landfill for the potential for vertical migration of gas from these wells. Wells that are
likely to cause vertical migration of gas shall be properly plugged and abandoned. The
requirements of the Well Construction and Abandonment Procedures of the State
Engineer's Office shall be met during any installation or abandonment of wells.
The selected remedy for landfill gas shall comply fully with all pertinent ARARs as
described in Table 11-1. The requirements of RCRA Subtitles C and D, the Clean Air
Act, and the Colorado Air Quality Act/Colorado Air Pollution Regulations shall be met
through the use of an enclosed flare. (The enclosed flare is not considered a "totally
enclosed treatment facility" for purposes of RCRA's use/reuse exemption.) The
requirements of the Colorado Hazardous Waste Act shall be met through proper disposal
if RCRA hazardous wastes or wastes sufficiently similar to hazardous wastes are
generated during the installation of gas monitoring or extraction wells.
11.4.1 Performance Standards and Point of Compliance
The landfill gas remedy shall meet the performance standards presented in Tables 11-1
and 11-7. Table 11-1 includes all ARARs for the selected remedy, including the landfill
gas portion of the remedy. Table 11-7 presents chemical-specific numeric standards for
the landfill gas remedy, some of which are based on ARARs. Table 11-7 performance
standards shall be met at the landfill gas compliance boundary, which is depicted in
Figure 11-3.
The landfill gas remedy also includes a Point of Action (POA) boundary (Figure 11-3).
The POA boundary for landfill gas borders the toe of the landfill mass. Table 11-6
identifies numeric standards for the POA boundary which are based on a concentration
which corresponds to a 1 x 1
-------
Flare emissions shall be measured at the enclosed flare stack and shall attain Table 11-7
performance standards. The flare shall meet the New Source Performance Standards (40
CPR Section 60.18); compliance shall be determined by testing for volatile organic
compounds using procedures approved by EP A.
The physical/surveyed location of the POA boundary and compliance boundary is
preliminary and shall be refmed during the RD and subject to EP A approval.
11.4.2 Contingency Measures
If Table 11-6 standards are exceeded at the POA boundary, or if Table 11- 7 performance
standards are exceeded at the compliance boundary, contingency measures shall be
implemented which may, at EPA's discretion, include the implementation of increased
extraction rates and/or the installation of approximately 26 additional extraction wells
within the landfill (Stage 3). The additional extraction wells would increase the total
amount of gas extracted, thereby reducing landfill gas pressures. In addition, EPA may,
at its discretion, require implementation of other technologies to further control landfill
gas migration. Use of these other treatment technologies and operation and maintenance
parameters shall be subject to EP A approval, in consultation with CDH.
11.5 Remedy for Soils and
Surface Water and Sediments
The selected remedy for soils, surface water, and sediments is No Further Action.
Specifically, the selected remedy for soils, surface water, and sediments includes the
following components:
.
Continued maintenance of the existing cover on the landfill mass
.
Continued maintenance of other covered areas, including the unnamed
creek drainage, vegetated areas, and the former tire pile area (after it is
reclaimed), including visual monitoring for soil and sediment erosion
.
As modified by this ROD, continued operation and maintenance of the
SWRA and all its components, as set forth in the Consent Order (Docket
No. CERCLA VII-91-12) and Modified Consent Decree (Civil Action 84-
F-1507), including the existing ground-water barrier wall
.
Mitigation of 0.87 acres of wetlands loss through construction of 0.87
acres of new wetlands
.
Periodic monitoring of surface water runoff
DENlOO153AD.WPS
11-14
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The selected remedy for soils, surface water, and sediments shall achieve the following
RAOs for soils, surface water, and sediments:
.
Protection of human health and the environment from direct contact or
ingestion of soils, surface water, and sediments containing contaminants
that exceed the performance standards
.
Protection of human health from inhalation of volatilized contaminants
from the soils, surface water, or sediments; and inhalation of contaminated
aUborne particulate matter from soils or sediments that exceeds
performance standards
.
Minimization of the production and migration of contaminated surface
water to the saturated zone and ground water
.
Minimization of the migration of soils and sediments by erosion or
entrainment by wind or water
.
Minimization of migration of contaminated surface water offsite and into
other media
11.5.1 Performance Standards and Points of Compliance
The selected remedy for soils, surface water, and sediments shall comply fully with the
performance standards (ARARs) described in Table 11-1.
The selected remedy shall include the continued operation and maintenance of the SWRA.
The components of the SWRA include a seepage collection system in the Section 6
segment of unnamed creek, a soil cover over the seepage collection system, the closure
of Ponds 3 and 4, and the upgraded treatment plant. The SWRA is currently being
operated and maintained in accordance with the requirements of the Final SWRA
Performance and Compliance Monitoring Plan, dated June 1992. The SWRA shall
continue to be operated and maintained in accordance with such plan unless otherwise
required by this ROD or by EP A. EP A may require modifications to the plan to ensure
that the requirements of this ROD are met.
The ground-water treatment plant shall meet water and air quality performance standards
presented in Tables 11-2 and 11-5 of this ROD, respectively, no later than 60 days after
the startup of a new or upgraded ground-water treatment plant, or no later than 60 days
after a determination by EP A that the existing treatment plant may be used without an
upgrade. These perfonnance standards shall supersede the perfonnance standards
identified in the SWRA Consent Order. However, until that time, the perfonnance
standards identified in the SWRA Consent Order shall remain in effect. The point of
compliance for the ground-water treatment plant effluent shall be existing Port 13 of the
treatment plant or its equivalent in the upgraded or new treatment plant.
DENlOO1S3AD.WPS
11-15
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The selected remedy for surface water and sediments shall also include the construction
of 0.87 acres of wetlands to replace those destroyed during installation of the SWRA.
The comPosition of the vegetation of the created wetlands shall be equal to the types and
percentages that were destroyed by the SWRA. The mitigation of wetlands shall fully
comply with the Executive Order on Protection of Wetlands.
Mitigation shall consist of in-kind replacement of destroyed wetlands, except for the mud
flats, which shall be replaced by vegetated wetlands. To account for mud flats
replacement, the area of each of the three identified species shall be increased in
proportion to the ratio of species extent to total extent of vegetated wetlands. As such,
based on 1:1 replacement, 0.31 acres of Cattail Marsh, 0.01 acres of Three-Square
Marsh, and 0.55 acres of Foxtail Barley Meadow shall be created.
The constructed wetlands shall be created in a location unaffected by Section 6 landfill
closure, the SWRA, current Section 31 landfill operations, or future Section 31 landfill
operations. Wetlands mitigation may occur offsite at a location more conducive to habitat
enhancement. The final location of created wetlands shall be specified during the RD and
shall be subject to EPA approval, in consultation with CDH.
Wetlands mitigation, which is conducted offsite and in connection with CERCLA
activities, shall be regulated by EPA. EPA shall provide the necessary coordination
among pertinent regulatory agencies such as the U.S. Army Corps of Engineers, U.S.
Division of Fish and Wildlife, and Colorado Department of Health.
A 5-year maintenance program shall be started on the date that construction of the created
wetlands is completed. This program shall establish successional trends and overall
viability of the created wetlands. Four aspects shall be monitored: surface water,
ground water, soils, and vegetation. The first year of monitoring shall determine if
corrective actions are necessary and the approximate acreage in which the wetlands
community has been established. Monitoring during years 2 through 5 shall document
functional equivalency.
Annual monitoring of the surface water runoff into the unnamed creek drainage basin
shall be conducted to evaluate the incidence of and potential for contaminant migration.
Potential or actual migration shall be evaluated with the installation of approximately
three automated surface water samplers. These samplers shall be installed on the western
edge of the former landfill mass, in the unnamed creek drainage, and near the confluence
of unnamed creek and Murphy Creek in Section 31. The specific parameters for annual
monitoring shall be evaluated during RD and shall be subject to EP A approval.
11.5.2 Contingency Measures
Contingencies for the SWRA were developed as part of the SWRA design effort (the
SWRA Contingency Plan dated May 1992; the Final SWRA Performance and
Compliance Monitoring Plan dated June 1992; and the Final O&M Manual dated June
DENlOOlS3AD.WP5
11-16
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1993), are included as part of the selected remedy, and shall be implemented if
(1) chemicals incompatible with treatment processes are detected in the treatment plant
influent; (2) a collection system, barrier wall, and/or injection trench malfunctions or is
inadequate to meet performance standards; (3) noncompliance with performance standards
occurs; (4) surface ponding of seepage water occurs; or (5) new seeps develop above the
engineered drain system. These contingency measures may be modified by EPA during
RD to ensure the requirements of this ROD are met.
11.6 Cost of the
Selected Sitewide Remedy
The selected sitewide remedy was evaluated for cost in terms of capital costs, annual or
operation and maintenance costs (O&M), and present worth cost. Capital costs include
the sum of the direct capital costs (materials, equipment, labor, land purchases) and
indirect capital costs (engineering, licenses, or permits). Annual costs include the cost
for labor, operation and maintenance, materials, energy, equipment replacement and
disposal, and sampling to operate the treatment facilities. Present worth costs include
capital costs and O&M costs calculated over a 30-year period. Table 11-8 summarizes
the capital, annual operations and maintenance, and present worth costs for the selected
sitewide remedy.
EP A integrated the OU s into a sitewide remedy to eliminate the duplication of costs
between different OUs. In addition, EPA incorporated modifications to the alternatives
in the selected sitewide remedy. The direct capital costs were revised to reflect the
integration of the OUs and modifications to the alternatives.
The present worth analysis is used to evaluate expenditures that would occur over an
assumed 30-year operation period by discounting all future costs to a common base year.
This allows the cost of remedial action alternatives to be compared on the basis of a
single figure representing the amount of money that, if invested in the base year and
disbursed as scheduled, would be sufficient to cover all costs associated with the remedial
action over its planned life.
Remedial design efforts may reveal that it is possible to reduce the original project cost
estimates. Reductions in the estimated costs could be the result of value engineering
conducted during the remedial design. Through the value engineering process,
modifications could be made to functional specifications of the remedy to optimize
performance and minimize costs. These changes would fall within the definition of
"non-significant modifications," as defmed by EP A guidance for preparing Superfund
decision documents.
For example, it may be determined that a reduction in costs could be effected by
non-significant changes to the type, quantity and/or cost of materials, equipment,
facilities, services, or supplies used to implement the remedy. It should be noted that this
DENlOOlS3AD.WPS
11-17
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type of design variance may have a noticeable impact on the estimated cost of the
remedy, but will not affect the remedy's ability to comply with perfonnance standards.
DENIOOIS3AD.WPS
11-18
-------
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ii' Closed ." :
:" , Landfill Area .1 !
\ ~ \ ." :
, " .1 '
" \ \ , !
\ \ " ,
\ . ~ 'I '
'.\ ~ , 'I
\. , 10 '
". " 'I;
"'.', :"I!
'""" ' .. . '
".,.... 'J"j
'-....,~,:.... LIMIT OF REFUSE ,':
'..... -.......;.. - - - - - - - - - - - - - - - - - - - - - - - - .-.."",. J
"''''-.J I~~~.~-!..~~~~~~,!~~~~~:---
N
i
Asbestos
Disposal
Area
Not to Scale
EAST QUINCY AVENUE
LEGEND:
---- Landfill Boundary (Fence Line)
-"- Ground-water Compliance Boundary
. - - - - Ground-water Action Boundary
Approximate Extent of Closed Landfill Area
The locations shown are approximate.
11-20
. Figure 11-2
GROUND-WATER COMPLIANCE BOUNDARY
AND GROUND-WATER ACTION BOUNDARY
LOWRY RECORD OF DECISION
DEN Graph/Lowry ROD/176
-------
C\}?-?-E~i \.,..~OF\\.LlNG ~~EA ----/ '
, ,"""""""" . Ba~~r Wall
, ../ 4r~'"
HA~ApS~EN Existing Ground-Water Treatment Plant " '-',
AVENUE '.- "',.,..:..-.-.- "-
,.._",-,_.~, ... '-"':t.,.-:~". .. ~[ /~ Co~mandPost '-:
Gate. ..'~ ~ f' t. --- .~I
M~.1 - ~ ~~ ..-h......" WMC ""~ .! GMP~13--
, ff ",:.~{r ~ Maintenance "~~ Section 6 I
pMP.10 ;j dMf-tio 1- Facility ';~ '
, '" r C'> I
I .~"a; ,
i ,-- '" '~!
, I
I .
~ ' !
r I GMP.2: -! GMP-12
i ,. Proposed Gas Point. !
~ ,~........ of -Compliance I Tire Shreds
~ I. " -,.., Boundary /, Monofill
i ii', / !
i: \: /!l !
I: ~. ---.... I
I. . ~ --:
: : ' ."0 ,
,: \ . ,'."./ "\' "
I: " , " . , ,
1 "'.. " ".' ~ " --. .... .
I: "._~. - . ..... : .." .. .. , I
1.~GMP-3 ",.....-.....,....' ! '~, .. --.. .' GMp.11
i i :...:_~.~-~..~.~_._... .,.' .' ..,/ !
- i i !
i i .! GMp.10
i .. GMP-4A !
d i i !
i ~ Closed Landfill Area !
, : I
\ \ I'
\ .. '
\... GMP-5A ( ~MP.9
"""" [ -,
-'<:... GMP-6A \ i
.~~.............. ~ OF REFUSE ) ,i
......... 0._. GMP.7 \..\\t.\ ~..-_.--,...................._-......-.,.
.-...~~-:=-=:-~::...._--.- GM~!-____J
Landfill Source Area
Landfill Gas Compliance Boundary
Point of Action Boundary
Asbestos
Disposal ~
Area
LEGEND:
----
.----
DEN GraplVlowry ROD/180
"
i:
Section 31
a'
N
!
~
'~f., rr;""';-"
NOTTO SCAlE
, :- -. .;~:"'':' .;.../,l:"",.i;'~'::'~:, ;;,~'':';::''':'\'<"-"~/~ 'k:!. ,,' -,'" "
'/ " ,,>.'~#><-~. ,
, ',', ,~,. ~
EAST QUINCY AVENUE
- Gas Monitoring Probe
The locations shown are approximate.
11-21
Figure 11-3
LANDFILL GAS COMPLIANCE AND
POINT OF ACTION BOUNDARIES
LOWRY RECORD OF DECISION
-------
Table 11-1
Selected Sitewide Remedy AltARs
Desc:riptioa Evaluation
. {j/iii://... ...........::::::::~~r~m!~~r!.I:;::!::::;;':::;:;;::::::::;;::;::::::!:::.:;:::'::::::::::::r::::;:':::::':::::!::::;!;I::::::;!:::::::::I;:':;::;::":;::!;;I:.::::.
Safe DriDkiDg Water Act
Establishes health-based standards for These regulations are relevant and appropriate becaU&e the
public drinking water systems (MCLs). shallow and deep ground water in the vicinity of the Lowry
Site is being used or may be used in the future as a source
of water for a public water system or private supply weDs.
Treated ground water from the treatment plant would be
injected into the shallow ground-water system. The
standards are pertinent to treatment plant effluent at the
point of injection as well as within the ground water at the
compliance boundary.
Establishes drinking water quality goals Non-zero MCLGs are relevant and appropriate since
set at levels of no known or anticipated shallow and deep ground water in the vicinity of the Lowry
adverse health effects, with an adequate Site is being used or may be used as a source of water for a
margin of safety (MCLGs). public water system or private supply wells.
Federal Water PoDution Control Ad (amended by the Clean Water Ad)
Establishes toxic pollutant effluent Relevant and appropriate for treatment plant effluent
standards for six groups of toxic because compound groups were detected in waste pit liquids
pollutants from manufacturers, and unnamed creek and Murphy Creek discharges to the
formulators, and applicators who South Platte River, which is a navigable water.
develop or use these compounds and
discharge to navigable waters.
Soid Waste Disposal Ad-RCRA Subtitle C
CitatiOD
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................
. . . . . . . . . . . . .
..... ........
'p'
",','..
. . . . . . .
',',',',
..
40 CFR Part 141
Subpart B
40 CFR Part 141
Subpart F
40 CFR Part 129
Toxic Pollutant Effluent
Standards
Page 1 Of~
Sets ground water protection standards The State of Colorado operates an approved delegated
for land disposal units. program for this portion of RCRA. See requirements under
Colorado Hazardous Waste Act. Relevant and appropriate
because the landfill operates like a hazardous waste
management unit.
""""........::::::..:;:::::::.:;::'::::'::":::,::.::::':~~~~f:~~~!l#.::~*~:':':}:.:::::::!;'.:::;:.::::';';:::':::;::=':::::::;...::::::::.:;::::..n:.;::':'::::'::::::::::::::;':!::::'::::::::.:::I::
Colorado Hazardous Waste Act
40 CFR Part 264
Subpart F
... ..... ...",
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6 CCR 1007-3 Part 264.94
Colorado Rules and
Regulations Pertaining to
Hazardous Waste-Ground
Water Protection Standard
5 CCR 1002-3
Regulation on Effluent
Limitation
5 CCR 1003-1
Colorado Primary Drinking
Water Regulations
DEN10015377 .WP5
Establishes concentration levels for 14
chemicals in ground water.
The concentration limits are relevant and appropriate to
ground water at the compliance boundary for ground water
and treatment plant effluent.
Colorado Water Quality CODtroI Ad
Establishes specific limitations on point Relevant and appropriate for discharge from treatment plant.
source discharges of wastewaters into
state waters and from specified industry
sources, specifies sampling and
analytical requirements.
Establishes health-based standards for
public water systems.
These regulations are relevant and appropriate because the
shallow and deep ground water in the vicinity of the Lowry
Site is being used or may be used in the future as a source
of water for a public water system or private supply wells.
Treated ground water from the treatment plant would be
injected into the shallow ground-water system.
11-22
-------
CitatiOD
\!\;~~~1~;~t~jr~~~~\~rjj1j~1\j~~)~;fr~r~~~j{~~~l~~~~~~~~~!~l~~~i)f~~~~\i:~;:f~~I~[:~~~~~~~~':
s CCR 1002-8
Section 3.11.0
Colorado Basic Standards
for Ground Water
and Section 3.12.0
Classifications and Water
Quality Standards for
Ground Water
S CCR 1002-8
Section 3.1.0
Basic Standards and
Methodologies for Surface
Water
S CCR 1002-8
Section 3.2.0
Classifications and Numeric
Standards
S CCR 1001-3
Regulation No.1
5 CCR 1001-4
Regulation No.2
DENlOOI5377.WPS
Table 11-1
Selected Sitewide Remedy ARARs
Descripbou
Hri:i:~'~~:~+i~~~(X~~~:>:\f::
These regulations establish standards for both classified and
unclassified ground water. The standards are applicable
because ground water (within non-alluvial and alluvial
aquifers) near the Lowry Site and ground water (within
alluvial aquifers) within the Lowry Site have been classified
for domestic and agricultural use-quality. Ground water
would be treated to meet these standards and then
discharged to the shallow ground-water system.
Murphy Creek and the unnamed creek are classified and
regulated as tributaries of the South Plane River Basin
(Stream Segment 16). Segment 16 is classified as
Recreation Class 2, Warm Water Aquatic Life Class 2, and
Agricultural Supply. Because of this classification,
statewide interim organic pollutant standards for aquatic life
segments (Section 3 .1.11 and Table C) are applicable to the
remedy. If surface-water discharge results from injection of
the treated water, surface water standards will be established
based on the most stringent surface water MAR.
Murphy Creek and the unnamed creek are classified and
regulated as tn"butaries of the South Plane River Basin
(Stream Segment 16). Segment 16 is classified as
Recreation Class 2, Warm Water Aquatic Life Class 2, and
Agricultural Supply. Based on the regulations, numeric
standards for protection of these three classified uses are
applicable. Cbemic:al-specific standards established for
Stream Segment 16 are applicable to the remedy. If
surface-water discharge results from injection of the treated
water, surface water standards will be established based on
the most stringent surface water ARAR.
Colorado .Air Qua6ty AdJ Air PoDution RegulatiOllS
Establishes a system for classifying
ground water and sets water quality
standards for such classifications.
Establishes basic standards and a
system for classifying surface waters of
the State, assigning standards, and
granting temporary variances for the
standard.
Used in conjunction with Basic
Standards and Methodologies Section
3.1.0. South Platte River Standards
(Section 3.8) establish numeric
standards for the South Platte River
Basin based on use classifications for
stream segments.
Establishes standards for emissions of
particulates, smoke, carbon monoxide,
and sulfur oxides.
Sets limits on odorous air c:ontaminants
and partic:uJates.
11-23
Page 2 of111
Evaluation
....
;:::::;:::::;:;;::;:;=:;:::;:::;:;:;::::::.::::::::
. ..... ...
.. ...
.....
......
. ...
.............
..
These regulations are applicable because air emissions will
occur at the ground water treatment plant, the gas treatment
system, and due to construction activities. These
regulations would be met for the air stripper/carbon
polishing treatment process, gas flaring system, and during
construction. Regulations for opacity and offsite transport
of visible fugitive emissions are applicable and must be
attained during constrUc:tion activities resulting in
disturbance of 5 acres or more in auainment areas or one
acre in nonauainment areas. The Lowry Site is in an
attainment area for sulfur oxides and lead and in a
nooattainmentarea for PM 10, ozone, and carbon
monoxide.
These regulations are applicable because air emissions will
occur at the site during all activities. Activities regulated
include activities such as soil movement or treatment plant
air emissions. These regulations would be met for all
activities including the air stripper/carbon polisbiog
treatment process, excavation of soil in the former tire pile
area, and movement of soil for construction of barrier walls
and gas collection and treatment system.
-------
Citation
n'" .
... ....... .....
............"'"''
..............,....... ...
............' ........
............""""'"
............. ............
.............'..',"'" .....
... . . ......
5 CCR 1001-10
Regulation No.8
5 CCR 1001-14
Ambient Standards
Table 11-1
Selected Sitewide Remedy ARARs
Description Evaluation
~::~~~~t~:::_4~:~::~@~t:~::~::::::::::~:::~:~:::~:~~:::::::~::::::::I::::::~:::::::::::!U::::.~:::~:!:::::r:::::!!;!!:::!!!:I:::!~!::
.....
'-".." ...
Sets emission control requirements for
hazardous air pollutants.
Establishes ambient standards for S01'
TSP, NOv CO, ozone, and PM 10.
Page 3 0111
These regulations are applicable because air emissions will
occur at the treatment plant and at the gas treatment sySlem.
These regulations would be met for the air stripper/carbon
polishing treatment process and for the gas flare. The lead
standards are applicable because they are ambient standards
that apply to aU sources. The beryllium provisions set out
emission limitations for stationary sources that are
applicable for aU sources. The hydrogen sulfide standards
are applicable to any actions emitting hydrogen sulfide.
The mercury standards are applicable if wastewater
treatment plant sludge is dried or incinerated.
These regulations are applicable because air emissions occur
at the treatment plant. These regulations would be met
because these parameters are not expected to be present. If
these parameters are detected above the regulated levels,
action will be taken to correct the problem.
TBCs. These standards were used to design the SWRA
when considering air pollution controls for the water
treatment plant. The plant will continue to meet these
standards.
Massachusetts
Allowable Ambient Levels
(AALs) and Threshold
Effects Exposure Limits
(TELs)
i(\'::::":~:{r\))}??:.::?~)~:))t)H... .. .. .. .. .......... .. ...H..... .!:.:.::.::.::.~...::.:.:.:....'....:.:.D.:.:is.........~.:::.:..:.:.~...r..:IC.... :.:.::.::.~......:.....:.:..:.: H. ..::.:.f-.;.;.;}1......:.~.:..:aer...:.:..:.::.:.. :.:aJ.::.::.:.:.:.::~.:~.::.:.::'.::.::.:~.::.::.::.::.::.:~.:~.::.}.:.::.~:.~:.:~. '.:.....:.:......... ::::~:@~:?::t~:::m:::~::::::~::~:::{:t}gtt
..........: ','.',:.:.:.;.;.;.:.:.:.:.:.:.:.:.:.:.:.'.:.:.:...:.:.::.:.;.:.;.:,:.;,;,;.:.; ........,',','.'.'.',',','.',',',',',',',',',',',',',',',',',',...,',',','.'..,',','
Solid Waste ~posal Ad - RCRA Subtitle D Requiremeats
Establishes minimum levels of Because the Lowry Site is a landfill and because
perfol'l1\lUlCe required of any solid decomposition gases have been detected, this requirement is
waste land disposal site operation. well suited to the situation and is relevant and appropriate 10
Part 241.20S-2(b) states the gas coDection and treatment system. Therefore, the gas
"decomposition gases should not be collection and treatment must meet these standards, which
allowed to concentrate in a manner that include mAintllinil\g methane below explosive limits.
will pose an explosion or toxicity
hazard. .
40 CFR Part 241
GuideliDes for the Land
Disposal of Solid Wastes
40 CFR Part 257
Criteria for Classification of
Solid Waste Disposal
Facilities & Practices
40 CFR Part 258
Regulations Concerning
Municipal Solid Waste
Landfills
DEN1 001 5377 .WP5
Establishes health-based air standards.
Establishes criteria for use in
determining which solid waste disposal
facilities and practices pose a
reasonable probability of adverse
effects on health or the environment
and thereby constiblte prohibited open
dumps.
Establishes design and operational
criteria for all DeW municipal solid
waste landfills or expansions of
existing facilities. The requirements
vary depending on the time frame that
the land disposal unit is used. Includes
closure and post closure care.
. If the landfill stopped receiving waste
prior to 10/9/91 it is not regulated
. If the landfill stopped receiving waste
prior to 10/9/93 the facility must
comply with final cover requirements
. If the landfill receives waste on or
after 10/9/93 the facility must comply
with all requirements of 40 CFR 258
Applicable for existing MSW landfills. The Section 6
MSW landfill is a closed landfill. Landfill cover
requirements are relevant and appropriate.
Explosive gas requirements (Part 258.23) are relevant and
appropriate since waste was not received after October 9,
1993, but the use of the requirement is well suited to the
situation. Therefore, methane monitoring within onsite
strucblres and at the facility property boundary is required.
Landfill cover requirements are relevant and appropriate
since waste was not received after October 9, 1991, but the
use of the requirement is weD suited to the situation.
Therefore, landfill cover maintenance is required.
11-24
-------
Citation
~j~~~fi)r~[~~\\fr~~[~1~~~[1~~j~)~j~j~f!~}fj~~~~~~~fi~i~~~i)~jj~~}~~~~~())
40 CFR Part 260-261
Identification and Listing of
Hazardous Waste
40 CFR Part 262
Standards Applicable to
Genera'tors of Hazardous
Waste
40 CFR Part 264 Subparts
B, C, and D
Standards for Owners and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
40 CFR Part 264
Subpart F
DEN1OOI5377.WPS
Table 11-1
Selected Sitewide RemMy ARARs
Description I
::::::::::::H::::~lf.$~~~8~~~:::(~::::::::f:
So6d Waste ~posaI Ad-RCRA Subtitle C Regulations
Defines those solid wastes that are
subject to regulation as hazardous
wastes under 40 CFR Parts 262-265
and Parts 124, 270, 271.
Establishes standards for RCRA
generators.
Establishes minimum standards that
define the acceptable management of
hazardous waste for owners and
operators of facilities which treat,
store, or dispose of hazardous waste.
Sets ground-water protection standards
for land disposal units.
Page 4 oUI
Evaluation
....
.........
......
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.....
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. ..
.........
. . . . . . . .
.... ..
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.. .
. .
The State of Colorado has an approved delegated program
for this portion ofRCRA. The regulations are applicable
for purposes of determining whether any of the materials
being treated or disposed are hazardous wastes. Materials
may also be compared to the waste listings to determine
whether any of the materials are sufficiently similar such
that RCRA regulations are relevant and appropriate.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground water
treatment plant residuals, solids excavated from the former
tire pile area, gas that is collected and treated, and waste
generated during construction activities for the barrier walls
or the gas extraction system. Therefore, waste generated
must meet these standards which include testing per 40 CFR
Part 261, temporary tanks or containers, inspection and leak
detection, and accumulation time. The State of Colorado
has an approved, delegated program under RCRA.
Because remediation activities constitute treatment and
storage activities (ground water treatment plant, gas
treatment, and residuals management), and because the gas
and water to be treated is sufficiently similar to RCRA
hazardous waste such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the ground water treatment and gas treatment
components of the remedy (!Dcluding residuals
management). Thus, flaring of the gas and treatment of the
groundwater must meet these standards, which include
waste analysis, site security, emergency control and
response equipment, personnel training, contingency
planning and implementation.
The State of Colorado operates an approved delegated
program for this portion of RCRA. See the requirements
under Part 264.94 of the Colorado Hazardous Waste Act.
Relevant and appropriate to ground water under the site
because the landfill operates like a solid waste management
unit. Therefore, ground water programs must meet these
standards, which include a monitoring and response
program that includes detection monitoring to identify the
presence of hazardous constituents in ground water;
complianc:e monitoring to determine whether the agency-
specified ground water protection standard is being met at
the identified complianc:e point; and corrective action that
prevents hazardous constituents from exceeding the
established concentration limits beyond the point of
complianc:e.
11-25
-------
Table 11-1
Selected Sitewide Remedy ARARs
Description Eva1uatioa
.............. ...... ......... ;:"::::H:::::::::::::::U::::::::::::::J~f~~%Y#.9~~~*'~~:::~g:::::'::::::::::::::::::::::::::::':!":::::!::::::!:::::::!!{':!:!:::::'::!::!:!;::::!::::"::::'::::::!':!:::::::::!i'::!::::!:
40 CFR Part 264 Subpart G Closure and post-<:losure care. Because ground water treatment and gas treatment coostitute
treatment of a waste that is sufficiently similar 10 RCRA
hazardous waste such that use of the requirement is weD
suited 10 the situation, the requirement is relevant and
appropriate 10 the ground water treatment and gas treatment
components of the remedy. Therefore, closure and post-
closure care for these treatment systems must meet these
standards which include removal of waste, waste residues,
contaminated system components, and conbmina~.d
subsoils; or closure with wastes and/or contamination in
place with containment systems and post-<:losure care 10
include ground water moniloring and iospection and
maintenance on containments and moniloring systems.
Because ground water treatment includes storage in
containers of a waste that is sufficiently similar 10 RCRA
hazardous waste such that use of the requirement is weD
suited 10 the situation, the requirement is relevant and
appropriate 10 the ground water treatment component of the
remedy. Therefore, container storage at the ground water
treatment plant must meet these standards, which include
maintaining wastes in containers that are in good condition
and compatible with the wastes they contain, providing a
containment system, managing ignitable and reactive wastes
away from the property line, keeping incompatible wastes in
separate containers and containment systems, and at closure
removing all wastes and decontaminating structures and
equipment.
Because ground water treatment includes storage in taoks of
a waste that is sufficiently similar 10 RCRA hazardous waste
such that use of the requirement is well suited 10 the
situation, the requirement is relevant and appropriate 10 the
ground water treatment component of the remedy.
Therefore, tank storage at the ground water treatment plant
must meet these standards, which include secondary
containment; spill and overflow controls; removal from
service if there is a leak, spill, or the tank is UDfit for use;
and at closure have all wastes removed and also remove or
decontaminate waste residues, containment system, soils,
structures, and equipment.
Because gas treatment constitutes thermal treatment, and
because the gas to be treated is sufficiently similar 10 RCRA
hazardous waste such that use of the requirement is weD
suited to the situation, the requirement is relevant and
appropriate 10 the gas flaring component of the remedy.
Thus, flaring of the gas must meet these standards, which
include emissions standards and operating constraints as
needed to ensure emissions standards arc met.
Citation
40 CFR Part 264
Subpart I
40 CFR Part 264
Subpart J
40 CFR Part 264 Subpart 0
DEN 1001 5377.WPS
Sets operating and performance
standards for container storage of
hazardous waste.
Sets operating and performance
standards for tank storage of hazardous
waste.
Sets standards for destruction and
removal efficiency, HCl emissions, and
particulate emissions from incineralors
or thermal treatment.
PageS Of~
11-26
-------
Table 11-1
Selected Sitewide Remedy ARARs
Description
:::::::ii'i:Ii:::i:ji:::::=::':::::::'j::=j::::::jim:::@:(:=:=:::.:::::(.:::Uj=:::::::\~~~~~::~H~~~(~~~
Citation
40 CFR Part 264
Subpart AA
40 CFR 265 Subpart P
Interim Standards for
Owners and Operators of
Hazardous Waste
Treatment, Storage, and
Disposal Facilities
40 CFR Part 265 Subpart
AA
40 CFR 265.17
40 CFR Part 268
l.aDd Disposal RestrictioDS
58 FR 48091 (9/14/93)
40 CFR Part 268
Universal Treatment
Standards
DENlOOlS371.WP5
Sets operation and performance
SIaDdards for air emissions from
process vents.
Standards for thennal treatment.
Sets operating and performance
standards for air emissions from
process vents.
Sets standards for mixing and treatment
of contaminated soils or the mixing and
treatment of potentially incompatible,
reactive, or ignitable hazardous wastes.
Establishes prohibitions on land
disposal unless treatment standards are
met or a "DO migration exemption" is
granted.
Establishes a concentration limit for
over 200 regulated constitUents in soil,
regardless of waste type, which must
be met before land disposal.
11-27
Page 6 or 111
Evaluation
", ........,,'.
." .............
.." "......"."
"',"",,,,,,,,,
"'Hu"',''''''
.......," .
.....
......
.....
. ..
... ..
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar to RCRA hazardous waste such that the use of the
requirement is well suited to the sitUation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include standards for process vents
and test methods and procedures.
Because gas f1aring constitUtes thermal treatment and
because the gas to be treated is sufficiently similar to RCRA
hazardous waste such that use of the requirement is well
suited to the sitUation. the requirement is relevant and
appropriate to the gas treatment component of the remedy.
Therefore, the gas treatment system must meet these
standards, which include general operating requirements,
waste analysis, monitoring and inspection, and closure.
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar to RCRA hazardous waste such that the use of the
requirement is well suited to the sitUation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include standards for process vents
and test methods and procedures.
Because the ground water treatment plant will mix and treat
potentially incompatible, reactive, or ignitable wastes which
may be similar to hazardous wastes, the requirement is
relevant and appropriate to the ground water treatment
plant. Therefore, the wastes must be analyzed to determine
compatibility, reactivity, and ignitability before treatment in
the treatment plant.
Because the solids excavation in the former tire pile area
and residuals from the ground water barrier walls and gas
extraction system construction and residuals from the
ground water treatment plant and gas extraction system
operations will be land disposed, the requirement is
applicable. The materials must be tested to determine if
they are a characteristic hazardous waste (per 40 CFR Part
262) and then must meet treatment requirements for land
disposal as required in the standards if they are hazardous
waste for which a treatment standard has been established.
For land disposal of residuals, other than soils, which are
not characteristic hazardous wastes, these requirements are
relevant and appropriate because the residuals are
sufficiently similar to listed hazardous waste such that use of
the requirements is well suited to the sitUation.
TBC for soil and sediments because it is a proposed
regulation. Excavated soils from the tire pile area must
meet these requirements.
-------
Table 11-1
Selected Sitewide Remedy ARARs Page 7 of 11
Citatioa DescripCion Evaluation
:::::::::::=:::=:::=::!:::::::::=:::::.:::=::::::::!:!::::::=!::H::::::::::::::!!!:::=:::::'::!:::~~i[~::=~H~~~~::~~:~~~~r)!:J::=::::::::::::::!::::::!::::::::::'!!!=:::::!=::::::::!!:!:::::M::::::=:I::!::!:::::::!':::::::f'I:::
Federal Water PoDntioa Coatrol Act (ameaded by the Clean Water Ad)
40 CFR Part 122 Establishes requiremems for Because stormwater discharges will occur from the landfill
NPDES Stormwater stormwater discharges related to and from any treatment process areas coDSInICted (such as
Regulations industrial activity. Stormwater IUDOff, the ground water treatment plant and the gas treatment
snow melt IUDOff, and surface IUDOff system), this requirement is applicable to stormwater
and drainage associated wilh industrial dischazges. Therefore, SIOrmwater discharges must meet
activity from remedial actions which these standards which include sampling, analysis, and
discharge to surface waters shall be treatment requirements. Implementation and enforcement
conducted in compliance with RCRA, has been delegated to the State of Colorado, see the
FWQC, CW A 1echnology-based stan- Colorado Water Quality Control Act.
dards, Colorado surface water quality
standards, monitoring requirements,
and best management practices.
40 CFR, Part 2301231 The discharge of dredged or fill Wetlands were destroyed during construction of the SWRA
Guidelines for Specification material into the waters of the U.S. is and must be mitigated during implementation of the selected
of Disposal Sites for prohibited without a permit. remedy by constructing new wetlands.
Dredged or Fill Materials
40 CFR, Part 440 Establishes radionuclide concentration Because the effluent from the ground water treatment plant
Effluent Guidelines and limits for liquid effluems from facilities could have radionuclides sufficiently similar to those
Standards for Ore Mining that extract and process uranium, regulated such that the requirement is well suited to the
and Dressing Point Source radium, and vanadium ores. situation, the requirement is relevant and appropriate to the
Categories ground water treatment plant effluent. Therefore,
contingencies have been made for the early detection of
radionuclides and for a treatment process to be added to
treat radionuclides at the ground water treatment plant.
Clean Air Act
40 CFR Part 60 Establishes performance standards for Relevant and appropriate for gas treatment. Proposed NSPS
New Source Performance DeW stationary sources of air for municipal solid waste facilities (Subpart WWW) is a
Standards pollutants. TBC (56 FR 24468 [SI30/91D.
40 CFR Part 61 Establishes emission standards for Because the ground water treatment plant has an air stripper
National Emission hazardous air pollutants from specific that is a source of air emissions and the gas treatment
Standards for Hazardous sources. system will have a flare, these two sources are sufficiently
Air Pollutants (NESHAPs) similar to source types in the regulations such that use of
the requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground water
treatment plant and the gas treatment system. Therefore,
the air stripper and gas flare must meet these standards
which include treatment levels for arsenic, beryllium, ben-
zene, vinyl chloride and radionuclide emissions.
Safe Driaking Water Ad
40 CFR Parts 144-147 Establishes standards for construction Applicable to injection of water from treatment plant. The
Underground Injection and operation of injection wells. requiremems include ConstIUCting, operating, and
Control Regulations Provides for protection of undeIgl'OUnd maintaining a well in a III8IIDCl' that does not result in
sources of drinking water. contamination of an undeJgl'OUDd source of drinking water
at levels that violate MCLs or otherwise affect the health of
persons. These requirements will be met by ensuring the
effluent from the groundwater treatment plant meets
standards that are protective of human health (based on
MCLs and risk-based concentrations).
DEN1OO1S377.WPS
11-28
-------
Table 11-1
Selected Sitewide Remedy ARARs
Description
::::.::.:::.r.r.::..:::.:::.:..:::::::::::::::::::::::::r::{:(:{:::;:;\:?....::... .....jf::::::::::::::::t::::~~........:.:).~.'...'..".:..H:$&.'....'.~:r::::::::::\:::::=f}::::::::::::H::(;::;::::::}:::::::::;::::::;::::;::>.::::..
. ... ..... ..... ...... . .
Colorado Solid Wastes Di1;posaI Sites and Facilities Act
Establishes standards for new solid Explosive gas requirements and landfill cover requirements
waste disposal facilities and defines are relevant and appropriate because waste was not received
those solid wastes. after October 9, 1993, but the use of the requirement is well
suited to the situation so the requirement is relevant and
appropriate to the existing landfill mass. Therefore, the gas
concentrations need to be maintained below the explosive
limits and maintenance of the landfill cover is required.
These requirements are applicable for the landfill gas
collection and treatment system and include monitoring
requirements in SUUctures and at the landfill boundary,
notification of gas excursions, and remediation activities if
explosive gas limits are exceeded.
Subslantive requirements are applicable to the gas extraction
system and landfill cover. Requirements include
maintaining the cover for 30 years, ground water
monitoring, describing uses of land during post closure
care, and certification at the completion of post closure
care.
Citation
6 CCR 1007-2 Section I
Regulations Pertaining to
Solids Waste Disposal Sites
and Facilities
6 CCR 1007-2 Section 2.3
6 CCR 1007-2 Sections 2.6
and 3.6
Establishes minimum standards for
landfill gas collection and treatment
systems.
Post closure maintenance and care.
Page 8 of 111
Evaluation
Colorado Hazardous Waste Ad
6 CCR 1007-3 Part 260-261 Defines those solid wastes subject to
Identification and Listing of hazardous waste regulations.
Hazardous Waste
6 CCR 1007-3 Part 262
Standards Applicable to
Generators of Hazardous
Waste
6 CCR 1007-3 Part 264
Subparts B, C, and D
Standards for Owuers and
Operators of Hazardous
Waste Treatment, Storage,
and Disposal Facilities
DENlooIS377.WP5
Establishes standards for RCRA
generators.
Establishes minimum standards that
define the acceptable management of
hazardous waste for owners and
operators of facilities which treat,
store, or dispose of hazardous waste.
11-29
The State of Colorado has an approved delegated program
for this portion of RCRA. Applicable to determining
whether substances are hazardous wastes under RCRA.
Because remediation activities will generate waste that will
be sufficiently similar to RCRA hazardous waste such that
use of this requirement is well suited to the situation, the
requirement is relevant and appropriate to the ground water
treatment plant residuals, solids excavated from the former
tire pile area, gas that is treated, and waste generated during
consuuction of the barrier walls or gas extraction system.
Therefore, waste generated must meet these standards which
include testing per 40 CFR Part 261, temporary tanks or
containers, inspection and leak detection, offsite shipping
procedures, and accumulation time. The State of Colorado
has an approved, delegated program under RCRA.
Because remediation activities coustitute treatment and
storage activities (ground water treatment plant, gas
treatment. and residuals management), and because the gas
and water to be treated is sufficiently similar to RCRA
hazardous waste such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the ground water treatment and gas treatment
components of the remedy (mcluding residuals
management). Thus, flaring of the gas and treatment of the
groundwater must meet these standards, which include
waste analysis, site security, emergency control and
response equipment. personnel training, contingency
planning and implementation.
-------
Table 11-1
Selected Sitewide Remedy ARARs
Description
::~t~:::::::::~:::::::::::::::::::~%~~~~#::~ffi:~!!:(~~Fi!:t::::::~::!::!:i:::::;::i:::i:::!!!::r;::i:::i::;::::!:=:::!;!!!:!!!i!!::!!;:;:i!::!!::i!:;!!iti::!!::!=::!!!;!J!i!
Sets ground-water protection standards The State of Colorado operates an approved delegaled
for land disposal units. program for this portion of RCRA. See the requirements
under Part 264.94 of the Colorado Hazardous Waste Act.
Relevant and appropriate to ground water under the site
because the landfill operates like a solid waste management
UM. Therefore, ground water programs must meet these
standards, which include a monitoring and respoose
program that includes detection monitoring to identify the
presence of hazardous cODStituents in ground water;
compliance monitoring to determine whether the agency-
specified ground water protection standard is beiDg met at
the identified compliance point; and correc:tive action that
prevents hazardous constituents from exceediDg the
established concentration limits beyond the point of
compliance.
Because ground water treatment and gas treatment coDStilUte
treatment of a waste that is sufficiently similar to R.CRA
hazardous waste such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the ground water treatment and gas treatment
components of the remedy. Therefore, closure and post-
closure care for these treatment systems must meet these
standards which include removal of waste, waste residues,
contaminated system components, and contaminaled
subsoils; or closure with wastes and/or contamination in
place with containment systems and post-closure care to
include ground water monitoring and inspection and
maintenance on containments and monitoring systems.
Because ground water treatment includes storage in
containers of a waste that is sufficiently similar to RCRA
hazardous waste such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the ground water treatment component of the
remedy. Therefore, container storage at the ground water
treatment plant must meet these standards, which include
maintaining wastes in containers that are in good condition
and compatible with the wastes they contain, providing a
containment system, managing ignitable and reactive wastes
away from the property line, keeping incompatible wastes in
separate containers and containment systems, and at closure
removing all wastes and decontaminating structures and
equipment.
Because ground water treatment includes storage in taDks of
a waste that is sufficiently similar to RCRA hazardous waste
such that use of the requirement is wen suited to the
situation, the requirement is relevant and appropriate to the
ground water treatment component of the remedy.
Therefore, tank storage at the ground water treatment plant
must meet these standards, which include secondary
containment. spill and overflow controls, removal from
service if there is a leak, spill, or the tank is untit for use,
and at closure have all wastes removed and also remove or
decontaminate waste residues, containment system, soils,
structures, and equipment.
Citation
.. """.. ,.....'
. . . . . . .. ..... ..... "'"
......"...... -......',-.
""""""",,"...... -,...
......"......... ...... '"'' ....
"''''''''''''..-..... ....
""""""'"''''''''''''''
.............................
.............................
"""''''''''....'".'.....'
"'''''''''''''.. ..............
"""''''''''''... ..........
................... ..
6 CCR 1007-3 Part 264
Subpart F
6 CCR 1007-3 Part 264
Subpart G
6 CCR 1007-3 Part 264
Subpart I
6 CCR 1007-3 Part 264
Subpart 1
DEN100IS377.WP5
I
Closure and post-closure care.
Sets operating and performance
standards for container storage of
hazardous waste.
Sets operating and performance
standards for tank storage of hazardous
waste.
Page!) or~
Evaluation
11-30
-------
Citation
~f~t~}(~j~~~~j~~~~j\~~jj~~~~1j~1~~~~~i!~~~~~f~\;~~~f1~~iiii~~~~::::'.. : ~ ~:.
6 CCR 1007-3 Part 264
Subpart 0
StandaIds for Owners and
Operators of Hazardous
Wast/= TSD Facilities
6 CCR 1007-3 Part 264
Subpart AA
6 CCR 1007-3 Part 265
Subpart P
6 CCR 1007-3 Part 265
Subpart AA
6 CCR 1007-3 Part 265.17
6 CCR 1007-3 Part 268
Land Disposal Restrictions
5 CCR 1001-5
Regulation No.3
DEN10015377 .WP5
Table 11-1
Selected Sitewide Remedy ARARs
DescriptiOD
:~*-~~~:~B~#~~:(~~~f...... ...........................
......,
Sets standards for destruction and
removal efficiency, Hel emissions and
particulate matter in excess of the
stated standard.
Sets operating and performance
standards for air emissions from
process vents.
Staodards for thermal treatment.
Sets operation and performance
standards for air emissions from
process vents.
Page 10 of 111
Evaluation
..
. ..
...
Because gas treatment constitutes thermal treatment, and
because the gas to be treated is sufficiently similar to RCRA
hazardous wast/= such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the gas flaring component of the remedy.
Thus, flaring of the gas must meet these standards, which
include standards for process vents and test methods and
procedures.
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar to RCRA hazardous waste such that the use of the
requirement is well suited to the situation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include general operating
requirements, waste analysis, monitoring and inspections,
and closure.
Because gas flaring constitutes thermal treatment and
because the gas to be treated is sufficiently similar to RCRA
hazardous wast/= such that use of the requirement is well
suited to the situation, the requirement is relevant and
appropriate to the gas treatment component of the remedy.
Therefore, the gas treatment system must meet these
standards, which include standards for process vents and
test methods and procedures.
Because the gas treatment has process vents from thermal
treatment and because the gas to be treated is sufficiently
similar to RCRA hazardous waste such that the use of the
requirement is well suited to the situation, the requirement
is relevant and appropriate to the gas flaring component of
the remedy. Thus, the gas treatment system must meet
these standards, which include general operating
requirements, waste analysis, monitoring and inspections,
and closure.
Because the ground water treatment plant will mix and treat
potentially incompatible, reactive, or ignitable wastes which
may be similar to hazardous wastes, the requirement is
relevant and appropriate to the ground water treatment
plant. Therefore, the wastes must be analyzed to determine
compatibility, reactivity, and ignitability before treatment in
the treatment plant.
Because the solids excavation in the former tire pile area
and constnlction residuals from the ground water barrier
walls and gas extraction system will be land disposed, the
requirement is applicable so the materials must be tested to
determine if they are a characteristic hazardous waste (per 6
CCR 1007-3 Part 262) and then must meet treatment
requirements for land disposal as required in the standards if
they are hazardous waste for which a treatment standard has
been established.
Colorado Air Quality AdJ Air PoBution Regulations
Requires filing of Air Pollution These regulations are applicable because air emissions will
Emission Notice (APEN) including occur at the treatment plant and at the gas treatment system.
estimation of emission rates. The air stripper/caroon polishing treatment process and the
gas flaring process must meet any substantive provisions of
these requirements.
Sets standards for mixing and treatment
of contaminated soils or the mixing and
treatment of potentially incompatible,
reactive, or ignitable hazardous wastes.
Establishes prohibitions on land
disposal unless treatment standards are
met or a "DO migration exemption" is
granted.
11-31
-------
.. .... ..::..::...:,f;::::::::::::::'::::;:::::::::'::::::::::::::::::~~~~~:::~$t.1~rm;:::::::::::;::':::::::?'::::;;:::::::::::::m;;,::::::::'::::::::::::::::J::::::::,::::J,::t:::m:::::::;::t::::::;
Executive Order 11990, Protection of WetIaDds
40 CFR. Part 6, Appendix A Action to avoid adverse effects, Applicable because wetlands have been identified and
minimize potential harm, and preserve destroyed at the Lowry Site during the SWRA. New
and eDhance wetlands, to the extent wetlands will be constructed as part of the remedy.
possible. Requires action to minimize
the destruction, loss,or degradation of
wetlands.
Federal Water Pollution Control Ad (CIeaa Water Ad)
Discharge of dredged or till material For areas of the site that have desiguated wetlands, a permit
into wetlands prohibited without a will not be required pursuant to Section 121 (c) of
permit. CERCLA, but the subSlaJUive requirements of Part 230 will
be applicable if wetlands that have been identified at the
Lowry Site are dredged or tilled during implementation of
the remedial activity.
::\:::::~oD4~i(~,~ffi$.~f¥.::::::::::::::::::::::::::::::::;:;;::;;:::::'::;::::Ut[[[I:::;I;;:::;:;:::;:;::;::::::::;I';
Certification of Federal Liceuses and Permits
Discharge of dredge and till material For areas of the site that have designated wetlands, a permit
into wetlands prohibited without a State will not be required pursuant to Section 121(c) of
certification. CERCLA, but the substantive requirements will be
applicable if wetlands that have been idelllified at the Lowry
Site are dredged or tilled during implementation of the
remedial activity.
Citation
............... ..
. . . . . . . . . . . .. .."
',,',',',',',',',"',',',',',,','
. ...
... .....
...
,'..
. .
........
5 CCR 1001-8
Regulation No.6
5 CCR 1001-9
Section n.C.2, Section V
Regulation No.7
Colorado Revised Statute
Section 25-12-103
2 CCR 402-4
2 CCR 402-2
State of Colorado Division
of Water Resources, 1988,
as revised-Colorado State
Eugineers Office
.....
40 CFR Part 230
Page 11 of ~
Table 11-1
Sdected Sitewide Remedy AltARs
.
DescriptioD Evaluation
..... .... .... .i:~~~:~R$t#!~:::~~)::::::,:::::'m::::::'[[['{;::::::'::::::::::::::I::;:::::::
Establishes standards for new stationary These regulations are applicable because air emissioDS will
sources including incinerators. Sets occur at the treatment p1aDt and at the gas treatment system.
discharge and performance rates and The air stripper/carbon polishing treatment process and the
opacity requirements. gas tJariDg process must meet these requirements which
include discharge and performance rates and opacity
requirements.
These regulations are applicable because air emissioDS will
occur at the treatment p1aDt and at the gas treatment system.
The air stripper/caIbon polishing treatment process and the
gas tJariDg process must meet these requirements which
include controls represellliDg reasonably available cODlroI
technology (RAC'I).
Colorado Noise Abatemeat Statute
Provides limits for noise based on time Applicable for all construction activities associated with the
periods and zones. remedy.
Water Well Pump IDst..n..tinn Contractors Ad:
Establishes standards for installation of Applicable because wells will be installed.
water wells and pumping equipment.
WeD ConstractionIAbaDdomaeat Requiremeots
Establishes standards for disposal or
spillage of VOCs.
Well construction/abandonment
requirements
Applicable for new wells and abandonment of existing
wells. Additional requirements may be added to ensure that
a migration pathway is DOt created.
: :.:.' ~,~.~,~,~,:. ~,:,~,~..; :.: :.' :.' ~.:.' ~.:.' ~.~.~.~.:.' =.' ;.' =.'. :. :.,: =.:.:,.: ~.~.~.:.:.'.': :.'.:.;.:.~ :.: :. ~.f =.' :.' ~:: . . . . . . . .. . . . . . .. """
-------
Table 11-2
Ground-Water CompliaDce IIouDdaI)' Perfol'llUUlCe Staodards
Sitewide Remedy Page 1 of5
PerfOI'lll8DCe Standard
Chemical (pgJl) Basis
0rpDics
1, l-Dichloroethanc - -
1,I-Dichloroethylene 0.068 B
1,2-Dichloroethylene(cis) 70 D
1,2-Dichlorethylene(trans) 100 D
1 ,1, I-Trichloroethane 200 D
1,1,2- Trichloroetbane 0.32 B
1,1,2,2- Tetrachlorctbane 0.089 B
1,2-Dibromo-3-cbloropropanc 0.2 D
1,2-DichlorobeDzene 600 D
1,2-Dichloroethanc 0.2 B
1,2-Dichloropropane 0.56 D
1,2-Diphcnylhydrazinc 0.05 D
1,2,4- TrichlorobcDZCUC 20 C
1,2,4,5- TetrachlorOOeDZCne 2 D
1,3-DichlorobeDzene 620 D
1,4-DichlorobeDzene 75 A
2-Butanone 780 C
2-cblorophenol 0.1 A
2-Hexanouc - -
2-Mcthy1naphthalcne 0.0031 A
(total PAHs)
2,3,7,8-TCDD (dioxin equivalcncc) .00000022 A
2,4-D(dichlorophcnoxyaceticacid) 70 D
2,4-Dichlorophcnol 21 A
2,4-Dinitrophenol 14 A
2,4,5 TP(trlchlorophenoxypropionic acid) 10 D
2,4,6- Trichlorophenol 2 D
4-McthyJ-2-pcntanone 780 C
Acetone 1,600 C
Alachlor 2.0 D
Aldicarb 3.0 D
Aldicarb Sulfone 2.0 D
Aldicarb Sulfoxidc 4.0 D
Aldrin 0.002 D
Atrazine 3.0 D
Benzene 0.62 B
Bcozidine 0.0002 D
Notes: A = ARARfI'BC.
B = Carcinogcnic (1 x 1~ target risk for adult.
C = Noncarcinogenic target concentration for child.
D = Colorado Basic Standards for Grouod Water for chcmicals that are DOt
COCs.
- = No information availablc.
DENlOO15381.WP5
11-33
-------
I Table 11-2 -,0151
G1'OIIIId-Water CompliaDce Boaadary Ped'OI"llUUlCe Standards
SiteMde Remedy
Ped'OI"llUUlCe Standard
CbEmicaI CJqy1) Basis
BeDZO(a)anrhracene 0.0031 (total PARs) A
BeDZO(a)pyrene (PAR) 0.2 D
Benzyl Alcohol - -
Bi.s('2-chloroethyl)ether 0.016 B
Bi.s('2-elbylhexyl)phlbalate 6.1 B
Bromodichloromethane 0.3 D
Bromoform 4.0 D
Carbazole - -
Carbofuran 36 D
Carbon tetrachloride 0.026 B
Chlordane 0.004 D
Chlorobenzene 100 D
Chloroethane - -
Chloroform 0.19 A
Chlorophenol 1 D
Dalapon 200 D
DDT Metabolite (DDE) 0.1 D
DDT 0.1 D
Di(2-ethylhexy1)adipate 400 D
Di(2-ethylhexyl)phlbalate 6 D
Di-n-Octylphlbalate - -
Dibenzofuran - -
Dibromochloromethane 14 D
DichlolOmethane 5 D
Dieldrin 0.002 D
Dinoseb 7 D
Diquat 20 D
Elhylbenzene 680 D
EudcIhall 100 D
Eudrin 0.2 D
Eudrin Aldehyde 0.2 D
Elhylenedibromide 0.05 A
Fluoranlbene 188 A
Glyphosate 700 D
Heptachlor 0.008 D
Heptachlor F¥oxide 0.09 D
Hexachlorobem:ene 1 D
Hexachlorobutadiene 1 D
Notes: A = ARARITBC.
B = Carcinogenic (1 x 1 (4) target risk for adult.
C = Noncarcinogenic target conceutration for child.
D = Colorado Basic Standards for Ground Water for chemicals that are not
COCs.
- = No information available.
DENl00lS381.WP5
11-34
-------
I Table 11-2 ..... 3 of51
Ground-Water Compliaace Bomadaly Periormaoce Standards
Sitewide Remedy
Perfol'JD8llCe Staadard
Chemical (pgII) Basis
Hexachlorocyclohexane, Alpha 0.2 D
Hexachlorocyclohexane, Gamma 0.004 D
(lindane)
Hexachlorocyclopentadiene 50 D
Isophorone 1,050 D
Malathion 2,500 D*
Methoxychlor 40 D
Methylene chloride 0.19 A
Monohydric phenol 1 D
Naphthalene - -
Nitrobenzene 3.5 D
Oxamyl (vydate) 200 D
PCBs 0.005 D
Pentachlorobe1lZene 6 D
Pentachlorophenol 0.71 B
Phenauthrene 0.0031 A
(total PAHs)
Phenol 1 D
Picloram 500 D
Simazine 4 D
Styrene 100 D
Tetrachloroethylene 1.5 B
Toluene 1,000 A
Toxaphene 0.03 D
Trans-l,3-dichloropropene 3.4 C
Trichloroethylene 2.6 B
Vmyl chloride 0.037 B
Xylenes (total) 10,000 D
IDorgaDics aod Mi
-------
I Table 11-2 .....".1
GI'OIIDd-Water CompliaDce Boaadary PerfonDaDCe StaDdards
Sitewide Remedy
PerfonDaDCe StaDdard
Chemical (,agII) Dais
Cobalt 50 A
Coliform (total) per 100 ml
-------
Table 11-2
GI'OIII1d-Water CompliaDce Boundary Penormauce Standards
Sitewide Remedy PageS 0'5
Performauce Standard
Chemical (,&gII) Basis
Tritium 880 pCiIl B
Tritium 20,000 pCiIl D
Uranium-234 3.0 pCiIl B
Urauium-235 20 pCiIl C
Urauium-238 5.2 pCiIl C
Xylenes (total) 10,000 D
Noees: A = ARAR/I'BC.
B = Carcinogenic (1 x 10"') target risk for adult.
C = NODCarcinogenic target concentration for child.
D = Colorado Basic Standards for Ground Water for chemicals that are not
COCs.
- = No information available.
DEN1OO15381.WPS
11-37
-------
Table 11-3
Ground-Water Point of Action Boundary Standards
Page 1 of 3
Basic Standards for
Ground Water
Parameter Name /l.2IL
1,1, I-Trichloroethane 200
1,1,2-Trichloroethane 3
1,1- Dichloroethylene 7
1,2,4,5-Tetr.achlorobenzene 2
1,2,4- Trichlorobenzene 70
1,2- Dibromo- 3-chloropropane 0.2
1,2-Dichlorobenzene 600
1,2- Dichloroethane 0.4
1,2-Dichloroethylene (cis) 70
1,2-Dichloroethylene (trans) 100
1,2-Dichloropropane 0.56
1,2-DiphenyLhydrazine 0.05
1,3- Dichlorobenzene 620
1,4- Dichlorobenzene 75
2,4,6- Trichlorophenol 2
2,4- Dichlorophenol 21
2,4-Dinitrophenol 14
Alachlor 2.0
Aldicarb 3.0
Aldicarb sulfone 2.0
Aldicarb sulfoxide 4.0
Aldrin 0.002
Atrazine 3.0
Benzene 5.0
Benzidine 0.0002
Benzo(a)pyrene (P AH) 0.2
Bis(2-chloroethvl)ether 0.03
Bromodichloromethane (HM) 0.3
Bromoform (HM) 4.0
Carbofuran 36
Carbon Tetrachloride 0.3
Chlordane 0.03
Chlorobenzene 100
Chloroform (HM) 6.0
DEN068.XLS
11-38
-------
Table 11-3
Ground- Water Point of Action Boundary Standards
Page 2 of 3
Basic Standards for
Ground Water
Parameter Name p.e/L
Dalapon 200
DDT 0.1
DDT Metabolite (DDE) 0.1
Di(2-ethylexyl)adipate 400
Di(2-ethylhexyl)phthalate 6
Dibromochloromethane (HM) 14
Dichloromethane 5
Dichlorophenoxyacetic Acid (2,4- D) 70
Dieldrin 0.002
Dinoseb 7
Dioxin (2,3,7,8-TCDD) 2.2xlO -7
DiQuat 20
Endothall 100
Endrin 2.0
Endrin Aldehyde 0.2
Ethylbenzene 680.0
Ethylene Dibromide 0.05
Glyphosate 700
Heptachlor 0.008
Heptachlor Epoxide 0.09
Hexachlorobenzene 1
Hexachlorobutadiene 1.0
Hexachlorocyclohexane, Alpha 0.006
Hexachlorocyclohexane, Gamma (Lindane) 0.2
Hexachlorocyclopentadiene 50
Isophorone 1050
Methoxychlor 40
Nitrobenzene 3.5
Oxamyl (vydate) 200
PCBs 0.005
Pentachlorobenzene 6
Pentachlorophenol 1.0
Picloram 500
Simazine 4
DEN068.XLs
11-39
-------
Table 11-3
Ground-Water Point of Action Boundary Standards
Page 3 of3
Basic Standards for
Ground Water
Parameter Name 1Lf!!L
Styrene 100
Tetrachloroethylene 5.0
Toluene 1000
Toxaphene 0.03
Trichloroethylene 5
Trichlorophenoxypropionic Acid (2,4,5- TP) 50
Vinyl Chloride 2
Xylenes (total) 10,000
Notes: The Standard is based on Colorado Basic Standards for Ground Water-
Statewide Standards (Table A).
DEN068.XLS
11-40
-------
-
-
J,..
-
Table 11-4
Surface Water Standards
Basic Standards and Methodologies for Surface Water
Site-Specific Standards for Use Classification
Recreation Class 2, Aquatic Life Wann Water Class 2. A2ricultural Pue 1 of 5
Agricultural Water Supply
Standard Segments Aquatic Life Aquatic Life PQL
("elL) (1!21L) (Acute) (Chronic) ("21L)
Of2anics
AcenaDhthene -- -- 1,700 520 10
Acrolein -- -- 68 21 10
Acrylonitrile -- -- 7,500 2,600 5
Aldicarb -- 10 -- -- 10
Aldrin -- 0.002 1.5 -- 0.1
Benzene -- 1 5,300 -- 1.0
Benzidine -- 0.0002 2,500 -- 10
Beryllium 100 (30 day) 0.007 -- -- --
BHC Hexachlorocyclohexane -- -- 100 -- 0.05
Bromodichlonnethane (HM) -- 0.3 -- -- 1.0
Bromoform (HM) -- 4 -- -- 1.0
Carbofuran -- 36 -- -- --
Carbon Tetrachloride -- 0.3 35,200 -- 1.0
Chlorobenzene -- 100 -- -- 1.0
Chlordane -- 0.03 1.2 0.0043 1.0
Chloroethvl Ether lbis-2-) -- 0.03 -- -- 10
Chloroform (HM) -- 6 28,900 1240 1.0
Chloro-4 Methvl-3 Phenol -- -- 30 -- 50
2-ChloroDhenol -- -- 4,380 2000 50
Chlorohvrifos -- -- 0.083 0.041 0.1
DOT -- 0.1 0.55 0.001 0.1
DOT Metabolite (DOE) -- 0.1 1,050 -- 0.1
DDT Metabolite-iDDD) -- -- 0.6 -- 0.1
Demeton -- -- -- 0.1 1.0
Dibromochloromethane (HM) -- 14 -- -- 1.0
1,2-Dichlorobenzene -- 620 -- -- 1.0
1,3-Dichlorobenzene -- 620 -- -- 1.0
1,4-Dichlorobenzene -- 75 -- -- 1.0
DEN067.XLS
-------
......
......
b
Table 11-4
Surface Water Standards
Basic Standards and Methodologies for Surface Water
Site-Specific Standards for Use Classification
Recreation Class 2, Aquatic Life Wann Water Class 2, A2ricultural Paae 2 of S .
Agricultural Water Supply
Standard Segments Aquatic Life Aquatic Life PQL
(,C2/L) (p2iL) (Acute) (Chronic) (te2/L)
1,2-Dichloroethane -- 0.4 118,000 20,000 1.0
1,I-Dichlorethylene -- 7 -- -- 1.0
1,2-cis-Dichlorethylene -- 70 -- -- 1.0
1,2-trans-Dichlorethylene -- 100 -- -- 1.0
2,4-Dichlorophenol -- 21 2,020 365 50
Dichlorophenoxyacetic Acid (2,4-D) -- 70 -- -- 2.02
1,4- Dichlorobenzene -- 75 -- -- 1.0
1,2-Dichloroethane -- 0.4 118,000 20,000 1.0
1,I-Dichlorethylene -- 7 -- -- 1.0
1,2-cis-Dichlorethylene -- 70 -- -- 1.0
1,2-trans-Dichlorethylene -- 100 -- -- 1.0
12,4-Dichlorophenol -- 21 2,020 365 50
Dichlorophenoxyacetic Acid (2,4-D) -- 70 -- -- 2.02
1 ,2- Dichloropropane -- 0.56 23000 5700 1.0
1,3-Dichloropropylene -- -- 6,060 244 1.0
Dieldrin -- 0.002 1.3 0.0019 0.1
2,4-Dimethylphenol -- -- 2,120 -- 50
2,4-Dinitrophenol -- 14 -- -- 50
2,6-Dinitrotoluene -- -- 330 230 10
Dioxin (2,3,7,8-TCDD) -- 2.2 x 10 -7 0.01 0.00001 0.02
1,2-Diphenylhydrazine -- 0.05 270 --
Endosulfan -- -- 0.22 0.056 0.1
Endrin -- 0.2 0.09 0.0023 0.1
Endrin Aldehyde -- 0.2 -- -- 0.1
Ethvlbenzene -- 680 32,000 -- 1.0
Fluoranthene (P AH) -- -- 3,980 -- 10
Guthion -- -- -- 0.01 1.5
,IHeDtachlor -- 0.008 0.26 0.0038 0.05
I\Heptachlor Epoxide I -- 0.09 0.26 0.0038 0.05
- - --- - - - ~ -- ----
-------
Table 11-4
Surface Water Standards
Basic Standards and Methodologies for Surface Water
Site-Specific Standards for Use Classification
Recreation Class 2. Aquatic Life Wann Water Class 2. A2ricultural
.....
.....
~
I.IJ
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocvclohexane, Alpha
Hexachlorocvclohexane, Gamma (Lindane)
Hexachloroethane
Hexachlorocvclonentadiene
Indeno(l,2,3-cd)nvrene (P AH)
Isophorone
Malathion
Methoxychlor
Mirex
Naphthalene (PAH)
Nitrobenzene
Parathion
PCBs
Pentachlorobenzene
Pentachloroohenol
Phenol
1,2,4,5- Tetrachlorobenzene
1,1,2,2-Tetrachlorethane
Tetrachloroethylene
Toluene
Toxanhene
1,1,1- Trichloretbane
1 , 1,2- Tricblorethane
(frichlorethYlene
2,4,6-Trichloroobenol
frrichlorophenoxypropionic Acid (2,4,5- TP)
Vinyl Chloride
DEN067.XLS
Agricultural
Standard
(U2/L)
--
Water Supply
Segments
(U2/L)
6
1.0
0.006
0.2
0.080
540
5
Aquatic Life
(Acute)
Aquatic Life
(Chronic)
--
--
90
0.0039
1.0
980
7
--
9.3
--
--
--
--
--
--
--
--
--
--
--
--
1050
--
117,000
--
0.1
0.03
0.001
620
--
--
--
40
--
--
--
--
--
2,300
27,000
0.065
2.0
0.013
0.014
--
--
3.5
--
--
--
--
0.005
6
200
5.7
2,560
--
--
--
9
10,200
--
--
--
--
2
--
--
--
2,400
840
--
--
--
5.0
1000
0.03
200
3
5
2.0
50
2
--
5,280
17,500
0.73
--
--
0.0002
--
--
--
--
9,400
45,000
--
--
21,900
970
--
--
--
--
--
--
--
--
--
--
n
PlU!e 3 of 5
PQL
(U2/L)
10
10
0.05
0.05
10
10
10
10
0.2
0.5
0.1
10
10
1.0
10
50
50
10
1.0
1.0
1.0
5.0
1.0
1.0
1.0
50
0.5
2
-------
-
-
t
Table 11-4
Surface Water Standards
Basic Standards and Methodologies for Surface Water
Site-Specific Standards for Use Classification
Recreation Class 2, Aquatic Life Wann Water Class 2. Aericultural Paae 4 of 5 .
Agricultural Water Supply
Standard Segments Aquatic Life Aquatic Life PQL
("elL) ("elL) (Acute) (Chronic) ("elL)
Inoreanics
Antimony -- 14 -- --
Aluminum -- -- 750 87
Ammonia (un-ionized as N) -- 500 site specific 60--100
Arsenic 100 (30 day) 50 360 150
Asbestos, fibers/l -- 30000 -- --
Barium -- 1,000 -- --
Boron 750 (30 day) -- -- -- --
Cadmium 10 (30 day) 10 (l day) hardness dep. hardness dep. --
Chloride -- 250,000 -- --
chromium (hexavalent) 100 (30 day) 50 (l day) 16 11
Chromium (trivalent) 100 (30 day) 50 (l day) hardness dep. hardness dep.
Copper 200 (30 day) 1,000 (30 day) hardness dep. hardness dep.
Cyanide (free) 200 (l day) 200 (l day) -- --
Dissolved Oxygen 3000 3,000 -- --
Fecal Coliform -- 2,000/loomi -- --
Fluoride -- 2,000 -- --
Iron -- 300 (30 day) a -- 1,000 (tot ree)
Lead 100 (30 day) SO (1 day) hardness dep hardness dep
Manganese 200 (30 day) 50 (dis)(30 day) -- 1,000
Mercury -- 2.0 (l day) 2.4 0.1
Nickel 200 (30 day) -- hardness dep. hardness del>.
Nitrate as N 100,000 10,000 (l day) -- --
Nitrite as N (N02-N) 10,000 1,000 (1 day) -- --
PH -- 5.0--9.0 -- --
Selenium 20 (30 day) 10 (1 day) 135 17
Silver -- 50 hardness dep. hardness dep.
Sulfide as H2S -- 50 -- --
-------
--
Table 11-4
Surface Water Standards
Basic Standards and Methodologies for Surface Water
Site-Specific Standards for Use Classification
Recreation Class 2. Aquatic Life Wann Water Class 2. Aflricultural Paee S of S
Agricultural Water Supply
Standard Segments Aquatic Life Aquatic Life PQL
(1A2/L) (Ufl/L) (Acute) (Chronic) (Ufl/L)
Sulfate -- 250,000 -- --
Thallium -- -- -- 15
Uranium -- -- hardness den. hardness dep.
Zinc 2,000 (30 day) 5,000 (30dav) hardness dep. hardness den.
Radionuclides
Cesium 134, pCill -- 80b -- -- --
Plutonium 238,239, and 240, nCi/1 -- 15h -- --
Radium 226 and 228, pCi/1 -- 5b -- --
Strontium 90, pCi/1 -- 8b -- --
Thorium 230 and 232 pCi/1 -- 60b -- --
ITritium, pCi/1 -- 20,OOOb -- --
......
......
~
UI
DEN067.XLS
-------
Table 11-5
Air Quality Performance Standards
Sitewide Remedy Page 1 of3
Concentration
(p.g/m3)
Annual 24-Bour
Average Average
Chemical /Element (AAL) (TEL) Other Source
Organics
1, 1, I-Trichloroethane 1038.37 1038.37 - Massachusetts Guidance
1,1,2- Trichloroethane 0.06 14.84 - Massachusetts Guidance
1,I-Dichloroethane - - 521 Noncarcinogenic Risk
1,1,2,2- Tetrachloroethane 0.02 18.67 - Massachusetts Guidance
1,2,4 Trichlorobenzene - - 11 Based on RfC
1,2-Dichloroethylene (total) 107.81 215.62 - Massachusetts Guidance
1,I-Dichloroethylene - - 0.049 Carcinogenic Risk
1,2-Dichlorobenzene (ortho) 81. 74 81.74 - Massachusetts Guidance
1,2-Dichloroethane 0.04 11.01 - Massachusetts Guidance
1,2-Dichloroethylene 107.81 215.62 - Massachusetts Guidance
1,2-Dichloropropane 0.05 94.23 - Massachusetts Guidance
1,4-Dichlorobenzene 0.18 122.61 - Massachusetts Guidance
2,3,7,8-TCDD (dioxin - - -
equivalence)
2,4-Dichlorophenol - - -
2,4-Dimethylphenol - - -
2,4-Dinitrophenol - - -
2-Butanone - - -
2-chlorophenol - - -
2-Hexanone 10.88 10.88 - Massachusetts Guidance
2-Methylphenol - - -
2-MethyInaphthalene 14.25" 14.25" - Massachusetts Guidance
4,4-DDT - - 0.0103 Based on Slope factor
4-Methylphenol - - -
4-Methyl-2-pentanone - - -
Acetone 160.54 160.54 - Massachusetts Guidance
Acrylonitrile 0.01 1.18 - Massachusetts Guidance
Aniline 0.14 2.07 - Massachusetts Guidance
Benzene 0.12 1.74 - Massachusetts Guidance
Benzo(a)anthracene - - -
Benzyl alcohol - - -
Bis(2-chloroethyl)ether - - -
j"V alue is for sum of naphthalene and 2-methyl naphthalene. ]
DENIOOIS369.WPS
11-46
-------
Table 11-5
Air Quality Performance Standards
Sitewide Remedy Page 2 of 3
Concentration
(pg/m3)
Annual 24-Hour
Average Average
ChemicailElement (AAL) (TEL) Other Source
Bis(2-ethylhexyl)phthalate - - -
Carbazole - - -
Carbon disulfide 0.27 0.27 - Massachusetts Guidance
Carbon tetrachloride 0.07 85.52 - Massachusetts Guidance
Chlorobenzene 6.26 93.88 - Massachusetts Guidance
Chloroethane 358.78 717.55 - Massachusetts Guidance
Chloroform 0.04 132.76 - Massachusetts Guidance
Chloromethane (methyl - - 0.56 Based on Slope Factor
chloride)
Dibenzofuran - - -
Dieldrin - - 0.000219 Based on Slope Factor
Di-n-Octylphthalate - - -
Ethylbenzene 118.04 118.04 - Massachusetts Guidance
Ethylenedibromide - - -
Fluoranthene - - -
Gamma BHC (lindane) 0.003 0.14 - Massachusetts Guidance
Heptachlor 0.001 0.14 - Massachusetts Guidance
Methylene chloride 0.24 9.45 - Massachusetts Guidance
Naphthalene 14.25" 14.25" - Massachusetts Guidance
NDMA - - 0.0001 Based on Slope Factor
PCBs 0.0005 0.003 - Massachusetts Guidance
Pentachlorophenol 0.01 0.01 - Massachusetts Guidance
Phenanthrene - - -
Phenol 52.33 52.33 - Massachusetts Guidance
Styrene 1.75 115.81 - Massachusetts Guidance
Tetrachloroethylene 0.02 922.18 - Massachusetts Guidance
Toluene 10.24 10.24 - Massachusetts Guidance
trans-l,3-Dichloropropene - - -
Trichloroethylene 0.61 36.52 - Massachusetts Guidance
Vinyl chloride - - 0.028 Carcinogenic Risk
Xylenes (total) 11.8 11.8 - Massachusetts Guidance
~Va1ue is for sum of naphthalene and 2-methyl naphthalene. I
DENl00lS369.~
11-47
-------
Table 11-5
Air Quality Performance Standards
Sitewide Remedy Page 3 00
Concentration
(pg/Df)
Annual 24-Bour
Average Average
ChemicalJElement (AAL) (TEL) Other Source
Inorganics
Ammonia 4.73 4.73 - Massachusetts Guidance
Arsenic - - 0.0007 Based on Slope Factor
Barium - - 0.5 Based on Unit Risk
Beryllium 0.0004 0.001 - Massachusetts Guidance
Cadmium 0.001 0.003 - Massachusetts Guidance
Chromium - - 0.000085 Based on Slope Factor
Lead 0.07 0.14 - Massachusetts Guidance
Manganese - - 1 Based on RfC
Mercury - - 0.3 Based on Unit Risk
Nickel 0.18 0.27 - Massachusetts Guidance
Selenium 0.54 0.54 - Massachusetts Guidance
Vanadium 0.27 0.27 - Massachusetts Guidance
.Value is for sum of naphthalene and 2-methyl naphthalene.
DENlOOlS369.WPS
11-48
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Table 11-6
Landiill Gas Point of Action Boundary
Standards
Chemical Standard-
(pg/m3)
1,I-Dichloreothylene 4.9
1,2- Dichloroethane 9.4
Benzene 29
Chloroform 11
Methylene chloride 520
Vinyl chloride 2.8
.Standard based on 1 Q4 excess cancer risk.
DENlOOlS369.VVPS
11-49
-------
Table 11-7
Landiill Gas Compliance Boundary Performance Standards
Sitewide Remedy
Chemical Performance Standard Basis
-------
-
-
I
VI
-
- Table 11-8
Cost Estimate Summary
Selected Sitewide Remedy
(1) (2) (3) = (I) + (2)
Annual Present Worth O&M Present Worth
OU Remedial Actions/Components Capital O&M (1=5%, n=30 years) Total
2/3 Gas Collection/Flare
Stage 1 (minus abandonment of wells) (630 sefm) $1,543,000 $237,000 $3,643,000 $5,186,000
Stage 2 (630 sefm) 226,000 21,000 323,000 549,000
Drum Removal (includes cover maintenance) 4,054,000 243,000 3,736,000 7,790,000
North Slope Cover 736,000 0 0 736,000
Indirects @ 80% Capital & 30% O&M 5,247,000 150,000 2,306,000 7,553,000
Subtotals 11,806,000 651,000 10,008,000 21,814,000
4/5 Section 6 Soil Monitoring 16,000 18,000 277,000 293,000
Surface Water Removal Action 41,000 789,000 12,129,000 12,170,000
Section 6 Sediment Monitoring 16,000 15,000 231,000 247,000
Section 31 Sediment Monitoring 16,000 15,000 231,000 247,000
Indirects @ 80% Capital & 30% O&M 11,000 251,000 3,858,000 3,929,000
Subtotals 160,000 1,088,000 16,726,000 16,886,000
116 Slurry Walls 2,841,000 83,000 1,276,000 4,117,000
Extraction Wells and Piezometers 261,000 11,000 169,000 430,000
Mobilization 100,000 0 0 100,000
Treatment System (20 gpm) 4,357,000 618,000 9,500,000 13,857,000
On site Subtitle D Landfill 966,000 218,000 3,351,000 4,317,000
Reinjection Trench 60,000 10,000 154,000 214,000
Long-term GW Monitoring 508,000 840,000 12,913,000 13,421,000
Infrastracture 278,000 30,000 461,000 739,000
Well Abandonment 97,000 0 0 97,000
Command Post Demolition 700,000 0 0 700,000
Decommissioning 375,000 0 0 375,000
Indirects @ 80% Capital & 30% O&M 8,434,000 543,000 8,347,000 16,781,000
Subtotals 18,977,000 2,353,000 36,171,000 55,148,000
Totals $31,000,000 $4,100,000 $63,000,000 $94,000,000
Note: Indirects include a 25 percent for contingency on capital costs and a 20 percent for contingency on O&M costs.
DENI0015049.WP5
-------
Section 12.0
Statutory Determinations
-------
Section 12.0
Statutory Determinations
Under CERCLA Section 121, EPA must select remedies at Superfund sites that are
protective of human health and the environment. CERCLA Section 121 specifies that
when complete, the selected remedial action for a site must comply with applicable or
relevant and appropriate environmental standards established under federal and state
environmental laws unless a statutory waiver is justified. The selected remedy must also
be cost effective and utilize permanent solutions and alternative treatment technologies or
resource recovery technologies to the maximum extent practicable. Finally, CERCLA
Section 121 includes a preference for remedies that employ treatment that permanently
and significantly reduce the volume, toxicity, or mobility of hazardous wastes as their
principal element.
12.1 Protection of Human
Health and the Environment
The following discussion describes how the risks posed through each pathway will be
eliminated, reduced, or controlled by the components of the selected sitewide remedy and
in doing so protect both human health and the environment. The selected remedy
protects human health and the environment by achieving performance standards that will
reduce the risk levels for individual contaminants at the Lowry Site to 1 x 1~, and
cumulative risk for all exposures and contaminants to between 1 x 104 and 1 x 10~.
The selected remedy protects human health through: containment of contaminated ground
water and collection and treatment of that ground water in an upgraded or new onsite
treatment facility; maintenance of a complete cover over the landfill mass and the
addition of cover material on the north face of the landfill; containment and collection of
landfill gases, treatment and destruction of those gases in an enclosed flare, and treatment
of gas condensate in the onsite treatment facility; excavation, treatment, and offsite
disposal of drums and associated contamination in the former tire pile area; construction
and operation of an adequate ground water/liquids treatment facility onsite; re-engineering
of the drainage in unnamed creek to intercept and contain contaminated seepage and
eliminate the release of contamination into sediments and surface water; implementation
of a comprehensive monitoring program for all media; and, establishment of institutional
controls to limit access, prohibit onsite construction, prohibit use of water beneath the
Lowry Site, and prohibit all incompatible offsite land uses and activities.
The selected remedy is protective of the environment because it addresses all concerns
identified by the ecological risk assessment for surface water, sediments, and surficial
soils. Environmental risks posed by contaminated surface water and sediments in
Section 6 are addressed by remedial actions, while surface water and sediments in
Section 31 are addressed through limiting exposure and continued monitoring.
DENlOO153AE.WPS
12-1
-------
The landfill gas collection and treatment systems will minimize landfill gas migration into
the offsite subsurface environment, thus reducing the mobility and volume of toxic
substances through their treatment. The selected sitewide remedy will also remove
contaminants from the gas through operation of an enclosed flare. The selected remedy
eliminates the risk of fire or explosion from the accumulation of methane by reducing
methane concentrations to less than 5 percent of the lower explosive limit at the boundary
of the landfill mass. These reductions will also minimize the potential threat of inhalation
of contaminants in landfill gas by future receptors.
According to the Baseline Risk Assessment, the estimated concentration of each
carcinogenic contaminant in landfill gas within a potential future onsite residence would
exceed a 1 x 1 ~ cancer risk level for each carcinogenic contaminant. This also would
be true for a hypothetical future offsite (200 feet west) residence if the structural slab of
the residence were cracked and gas diffused in. Installation of the gas collection and
flare systems will reduce the offsite risk of cancer from these pathways. Collection of
landfill gas will also reduce the potential for gas to contaminate ground water.
The ground-water barrier walls and collection systems will minimize the potential for any
future offsite migration of contaminated ground water. The upgradient containment,
collection and diversion system will also inhibit offsite ground water from flowing into
the Lowry Site's subsurface environment.
Containment and treatment of contaminated ground water will, over time, reduce the
contaminant concentration in ground water on site. Shallow ground water beneath the
Lowry Site is not currently used. Deep ground water beneath the Lowry Site is used for
industrial supply. Shallow and deep ground water downgradient of the Lowry Site is of
domestic- and agricultura1-quality and is used by nearby residents and farmers. The
baseline cancer risk associated with the potential future ingestion of onsite shallow ground
water within the waste-pit source area is estimated as 1 x 10"2. The baseline noncancer
hazard index is estimated as 47 for this potential future pathway. These risks are
expected to decrease over time as existing ground water within the shallow aquifer is
treated and flow through the Lowry Site is reduced. Residual risk after implementation
of the selected remedy cannot be quantitatively estimated.
Operation of the SWRA will eliminate the potential future threat of exposure from direct
contact and incidental ingestion of contaminated surface water and sediments. The
baseline cancer risks associated with the potential future ingestion of onsite surface water
and sediments (as they existed before the SWRA) are estimated as 8 x 104 and 9 x lQ-6,
respectively. The baseline noncancer hazard index for ingestion of surface water is
estimated as 2, and the baseline noncancer hazard index for the ingestion of sediments is
below 1. Baseline cancer and noncancer risks have been reduced to acceptable levels as
a result of the SWRA. The hydraulic connection between ground water and surface
water within the unnamed creek has been eliminated and thus, surface water is no longer
contaminated above performance standards. Sediments within unnamed creek have been
covered as a result of the SWRA, and thus, potential exposure to Section 6 sediments has
been eliminated. These measures will be operated and maintained as part of the selected
DENlOOI53AE.WPS
12-2
-------
remedy. Institutional controls and access restrictions will eliminate the potential for
exposure to surface water and contaminated sediments in Section 31. Monitoring will
provide a mechanism to detect contaminant migration.
Excavation of contaminated solids from the former tire pile area will eliminate the poten-
tial for future direct contact, incidental ingestion, and inhalation. The baseline
carcinogenic risks estimated for a hypothetical future onsite resident within the former
tire pile area are 2 x 10-5 for ingestion and inhalation (inorganics and organic chemicals).
These risks will be eliminated with excavation of the contaminated solids. In addition,
excavation of contaminated solids will eliminate them as a potential source of further
ground-water contamination.
Cap improvements on the north slope and containment of the landfill mass will eliminate
the possible exposure of receptors to physical and chemical hazards associated with con-
taminated solids and landfill waste. In addition, the north slope cover will prevent
infiltration of precipitation and thus reduce the potential for leachate generation.
Institutional controls will prohibit future land uses that are incompatible with or that could
inhibit or impair the effectiveness of the on- and potential future offsite remedial actions.
Monitoring of ground water, gas, the SWRA, soil, sediments, ground-water treatment
plant effluent, and surface water will assure that there is early warning of any failure of
the selected sitewide remedy. These requirements include, but are not limited to: perfor-
mance and compliance monitoring of the existing ground-water barrier wall, injection
trench, SWRA collection system, and existing ground-water treatment facility; soil and
sediment erosion monitoring; surface water runoff monitoring; monitoring of gas migra-
tion; and ground-water monitoring for detection of potential vertical and/or horizontal
contaminant migration.
There will be no unacceptable short-term risks or cross-media impacts. Short-term effec-
tiveness is discussed in detail in Section 12.4.3. Cross-media impacts were evaluated in
terms of contaminant transfer to air, soil, ground water, surface water, and gas.
12.2 Compliance with ARARs
Under Section 121(d)(I) of CERCLA, remedial actions must attain standards, require-
ments, limitations, or criteria that are "applicable or relevant and appropriate" under the
circumstances of the release at a site. All ARARs would be met upon completion of the
selected site wide remedy at the Lowry Site.
The selected sitewide remedy of additional capping, excavation of contaminated solids in
the former tire pile area, ground-water containment and treatment, active landfill gas
collection and treatment, operation and maintenance of the SWRA, and institutional
controls will comply with all Federal and State applicable or relevant and appropriate
chemical-, action-, and location-specific requirements (ARARs). Federal and State
statutes and regulations pertinent to the selected remedy are discussed in Section 11.0.
DENlOOlS3AE.WP5
12-3
-------
The specific ARARs and TBCs for the selected sitewide remedy are presented in
Table 11-).
12.3 Cost Effectiveness
EP A has detennined that the selected sitewide remedy will provide overall effectiveness
proportional to its costs and is, therefore, cost effective. In order to make this determi-
nation, EPA compared the costs of components of the selected remedy to the alternatives
evaluated during the FSs, as described below. A description of cost estimating
procedures is provided in Subsection 8.1.
12.3.1 Shallow Ground Water and Subsurface
Liquids (OU 1) and Deep Ground Water (OU 6)
For ground water alternatives (OUs 1&6), Section 9.0 of this ROD provides the capital
costs, annual operation and maintenance costs, and the present worth of each alternative.
The selected ground-water remedy, Modified Alternative GW-5 (the North Boundary and
Toe of Landfill and Lateral Barrier Wall, Collection and Treatment System, Plus
Upgradient Containment, Collection and Treatment alternative), is comparable in cost to
Alternatives GW-3 (the North Boundary, Toe of Landfill Containment, Collection and
Treatment alternative), GW-5 (The North Boundary, Toe of Landfill, Lateral Contain-
ment, Collection and Treatment alternative), and GW-6 (the North Boundary, Toe of
Landfill, and Waste-Pit Pumping alternative), but will be more effective than these alter-
natives at preventing offsite migration of contaminants. Unlike these other alternatives,
the selected ground-water remedy includes the immediate design and construction of
containment and collection systems on all sides of the Lowry Site.
Alternative GW-6 results in a slightly greater reduction of volume of contaminants than
the selected remedy; however, this alternative would not eliminate the source and the
potential for off site migration of contaminants would still exist. Thus, the additional cost
of this alternative would not be warranted.
The selected ground-water remedy is more expensive than Alternatives GW -1 (the No
Further Action alternative) and GW-2 (the North Boundary Containment alternative), but
it is also more effective at containing and treating contaminants than these alternatives.
Alternative GW -4 (the North Boundary, Upgradient Containment Plus Multilayered Cap
alternative) is more expensive than the selected remedy, but would be less effective
because it would not include lateral containment.
12.3.2 Landfill Solids (OU 2)
Section 9.0 of this ROD provides capital costs, annual operation and maintenance costs,
and present worth costs for Landfill Solids (OU 2). Although the selected landfill solids
remedy, Modified LFS-4 (the Drum RemovallOffsite Disposal/North Face Cover
DENlOOlS3AE.WPS
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alternative), is the most expensive of the alternatives evaluated, it offers greater long-term
effectiveness and permanence and a significantly greater reduction of toxicity, mobility,
or volume through treatment than any of the other alternatives. This is because the
selected remedy will excavate, treat, and dispose offsite a much larger volume of
contaminated solids from the former tire pile area than any of the other alternatives. The
effectiveness of the selected remedy is also greater because it includes 2 feet of additional
cover on the north slope of the landfIll mass, which will reduce the potential for exposure
to landfill solids and for infiltration of water into the landfill mass.
12.3.3 LandrdI Gas (OU 3)
Section 9.0 of this ROD provides cost information for remedial alternatives evaluated for
Landfill Gas (aU 3). The selected landfill gas remedy, Modified LFG-3 (the Gas
Collection/Enclosed Flare alternative), is slightly more expensive than Stage 1 of
Alternative LFG-3 (the Gas Collection/Enclosed Flare alternative) and slightly less
expensive than Stage 1 of Alternative LFG-5 (Gas Collection/Enclosed Flare and Heat
Recovery), but includes significantly more extraction wells than either alternative, and
thus, will be more effective at preventing offsite migration of landfill gas and dangerous
buildup of gases onsite. The selected remedy will also result in a greater reduction of
toxicity, mobility, and volume of contaminants through treatment.
Stage 2 of Alternative LFG-3 would be as effective and offer the same reduction in
toxicity, mobility, and volume through treatment as the selected remedy, but would be
more expensive because it would involve the immediate abandonment of existing wells
and would involve remobilization for Stage 2 construction.
Stage 2 of Alternative LFG-5 would be as effective and offer the same reduction in
toxicity, mobility, and volume through treatment as the selected remedy, but would be
more expensive because it would involve: installation of heat recovery equipment; the
immediate abandonment of existing wells; and would involve remobilization for Stage 2
construction. Alternative LFG-5 would offer the benefit of heat recovery, but an
economical use for the heat has not been identified.
The selected remedy is more expensive than Alternative LFG-2 (the No Further Action
alternative), but Alternative LFG-2 will not prevent the migration of landfill gas offsite or
reduce the toxicity, mobility, or volume of contaminants through treatment. Alternative
LFG-2 is not an effective remedy.
12.3.4 Soil (OD 4)
For soil (aU 4), Section 9.0 of this ROD summarizes cost data for each alternative. The
selected remedial alternative for soil, Alternative SOIL-l (No Further Action), is the least
costly option. The remaining alternatives are more expensive without providing
significant additional short-term or long-term effectiveness. Contaminant concentrations
in soils are already at protective levels, and therefore, excavation or dust control provide
DENIOOIS3AE.WPS
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no added benefit. None of the alternatives reduces toxicity, mobility, or volume through
treatment, because no alternative involves treatment.
U.3.S Surface Water (OU S)
For surface water (OU 5), the SWRA was evaluated for its effectiveness and integration
into the sitewide remedy. Because the SWRA was deemed effective in eliminating
surface water exposures at the Lowry Site and could be fully integrated into the sitewide
remedy, it was the only alternative retained. The design life of the SWRA was
investigated to ensure full integration with the components of the sitewide remedy. The
costs for the SWRA are provided below:
Alternative SW-l, No Further Action
Capital Costs - $41,000
Annual O&M Costs-$790,000
Present Worth -$12, 100,000
U.3.6 Sediments (OU S)
For sediments that are part of OU 5, the remedial alternatives are discussed by location,
in either Section 6 or Section 31. For Section 6 sediments, Section 9.3 of this ROD
summarizes costs for each alternative. The selected remedy, SED6-1 (the No Further
Action alternative), is the least expensive alternative, will be virtually as effective as
Alternative SED6-2 in the long term, and will be as or more effective than Alternative
SED6-2 in the short term because no construction is required. Neither alternative
includes treatment.
For Section 31 sediments (OU 5), Section 9.3 of this ROD summarizes costs for each
alternative. The selected remedial alternative for Section 31 sediments, Alternative
SED31-1 (No Further Action), is the least costly option. The remaining alternatives are
more expensive without providing additional short-term or long-term effectiveness.
Contaminant concentrations in sediments are already at protective levels, and therefore,
capping, excavation, or access restrictions provide no added benefit. None of the
alternatives reduces toxicity, mobility, or volume through treatment, because no
alternative involves treatment.
U.3.7 Selected Sitewide Remedy
The net present-worth value for the selected sitewide remedy is $94,000,000 (see Table
11-8 for equated cost summaries for the selected sitewide remedy). Because there are no
significant cross-media impacts, and since each of the selected components has been
demonstrated to be cost effective, the sum of the components is also cost effective.
Therefore, EP A has determined that the sitewide remedy is cost effective in accordance
with Sections 300.430(f)(I)(i)(B) and 300.430(f)(I)(ii)(D) of the NCP.
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12.4 Utilization of Permanent Solutions and
Alternative Treatment Technologies (or Resource Recovery
Technologies) to the Maximum Extent Practicable
EP A has determined that the selected sitewide remedy utilizes permanent solutions and
alternative treatment technologies, or resource recovery technologies, to the maximum
extent practicable because it uses state-of-the-art treatment technologies for landfill gas
and ground water. In addition, the removal, treatment, and disposal of wastes in the
former tire pile area will achieve a permanent solution for those wastes. Although the
selected sitewide remedy is in large part a containment remedy, the remedy offers the
best balance of tradeoffs among the five primary balancing criteria and further use of
treatment as evaluated in the RlIFSs is not practicable. State and community acceptance
were also considered in making this determination.
Since the selected sitewide remedy is in large part a containment-based remedy, it is
consistent with Directive No. 9355.0-49FS Presumptive Remedy for CERCLA Municipal
Landfill Sites; however, every effort has been made to treat the landfill gas and ground
water within the containment system. The selected remedy will ensure the containment
of ground water on the northern, eastern, western, and southern boundaries, and will
collect ground water for treatment at each of these locations. In addition, ground water
will be collected for treatment at the toe of the landfill. Gas will be collected at the
eastern, western, and southern boundaries of the landfill mass and within the landfill
mass and treated. In addition, the removal and offsite treatment of accessible waste
within the former tire pile area (the principal threat in the former tire pile area) is
consistent with the statutory requirement.
Of the alternatives that meet EPA's two threshold criteria of overall protection of human
health and the environment and compliance with ARARs, EP A has determined that the
selected sitewide remedy best balances the tradeoffs of the alternatives as they relate to:
long-tenn effectiveness and permanence; reduction in toxicity, mobility, or volume
achieved through treatment; short-term effectiveness; implementability; and cost.
The following discussion of tradeoffs among alternatives is based on a comparison to the
five primary balancing criteria listed above, and the two modifying criteria of State and
community acceptance.
12.4.1 Long-Term Effectiveness and Permanence
Ground Water
Of the alternatives evaluated, the selected ground-water remedy would offer the greatest
long-tenn effectiveness and permanence because it addresses the movement of
contaminants from all sides of the Lowry Site. The selected remedy will immediately
prevent potential offsite migration of contaminants to the south, east, and west, using
barrier walls and collection systems. Barrier walls are a permanent form of containment
and have been proven effective over the long term at the Lowry Site. The selected
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ground-water remedy also includes treatment of contaminated ground water and is the
only alteplative that fully contains and collects contaminants migrating to the north, east,
west, and south. In addition, the selected remedy will provide for collection of contami-
nated ground water at the toe of the landfill mass. Contamination will be captured closer
to the source, thereby avoiding further contamination of the aquifer downgradient of the
landfill mass. The selected remedy effectively reduces the long-term potential for
contaminated ground-water migration.
Landf"Ill Solids
The selected remedy would provide the greatest long-term effectiveness and permanence
because portions of the former tire pile area will be excavated and the largest volume of
contaminated material will be removed relative to the remaining alternatives. This
remedy will permanently remove contaminated material from the Lowry Site. In
addition, the selected remedy will provide 2 feet of additional cover on the north face of
the landfill mass, thus providing greater containment and long-term effectiveness and
permanence in the landfill area than the other alternatives.
Landf"ill Gas
The selected remedy will provide the greatest long-term effectiveness and permanence
because it will provide a more extensive gas extraction system throughout the landfill
mass, and will be less dependent on gas monitoring activities than other alternatives.
Soils
The selected remedy will provide long-term effectiveness and permanence through
institutional controls. The risks associated with the soils are within EPA's acceptable risk
range. Therefore, the selected remedy would offer acceptable long-term effectiveness
and permanence.
Surface Water
The SWRA has been constructed, has operated reliably, and has met performance
standards. The SWRA has been designed for long-term operation and will be monitored
and maintained such that it continues to achieve performance standards. Thus, the
SWRA will achieve long-term effectiveness and permanence.
Sediments
In Section 6, the sediments have already been covered as part of the SWRA. The
selected remedy will provide long-term effectiveness and permanence through continued
maintenance of the cover. The selected remedy for Section 31 sediments
would provide acceptable long-term effectiveness and permanence because the risks
associated with the sediments are within EPA's acceptable risk range.
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12.4.2 Reduction of Toxicity, Mobility,
or Volume Through Treatment
Ground Water
The selected remedy will provide substantial reduction of toxicity, mobility, and volume
through treatment by extracting highly contaminated ground water from the alluvium at
the toe of the fonner landfill. In addition, the selected remedy will provide for extraction
and treatment of contaminated ground water from the northern, eastern, western, and
southern boundaries of the Lowry Site. Because it would extract and treat waste-pit
liquids, Alternative GW -6 would be the only alternative which would treat a greater
volume of material than the selected remedy. However, Alternative GW-6 does not
compare favorably to the selected remedy with respect to other criteria.
LandiUI Solids
The selected remedy will provide the greatest level of excavation and treatment of
contaminated solid material, thereby providing the most effective reduction of toxicity,
mobility, and volume through treatment.
Landf"ill Gas
The selected remedy will provide the greatest reduction of toxicity, mobility, and volume
by extracting and treating more gas from the eastern, western, and southern portions of
the landfill mass than any of the other alternatives.
Soils and Sediments
None of the alternatives, including the soils and sediments selected remedies, result in a
reduction of toxicity, mobility, or volume through treatment.
Surface Water
Under the selected remedy, the SWRA would reduce the volume of contaminants through
collection and treatment of contaminated alluvial seepage.
12.4.3 Short-Term Effectiveness
Ground Water
All of the alternatives would have reasonable short-term effectiveness. The selected
remedy would include a ground-water extraction system, at the toe of the landfill, for
collection of highly contaminated ground water. During construction of this system,
workers and the community would potentially be exposed to higher risks from the
presence of volatile organic compounds in the soil. However, these risks are not
DENlOO153AE.WPS
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anticipated to be significant during the 3-year design and construction period.
It has also been demonstrated that workers at the Lowry Site, as well as the community,
can be adequately protected during construction through the routine application of
accepted health and safety practices. The selected remedy will achieve overall protection
in a shorter time frame than any other alternative because containment systems would be
immediately designed and installed on the eastern, western, and southern sides of the
Lowry Site.
Landiill Solids
The selected remedy is not the best alternative considered under this criterion. The No
Further Action alternative (LFS-2) would have the greatest short-term effectiveness
because it would pose no adverse short-term effects to workers, the community, or the
environment and would take the least amount of time until protection was achieved.
However, potential short-term risks to construction workers associated with excavation of
contaminated materials from the former tire pile area can and will be controlled through
the use of appropriate health and safety measures.
Landiill Gas
The selected remedy poses minimal short-term risks in connection with the required
construction activities. These risks would apply primarily to onsite workers during
construction. Protectiveness will be achieved after construction is complete. Alternative
LFG-2 (the No Further Action alternative) would pose no adverse short-term risks to
workers because there would be no construction activities, but this alternative would not
eliminate potential short-term risks from gas buildup and migration, and thus, would not
be effective in the short-term.
Soils
The selected remedy would not involve soil disturbance and, therefore, would provide
maximum short-term protection to workers, the environment, and the community. The
risk from soils are already within EP A's acceptable risk range and therefore the time
until protection is achieved is immediate.
Surface Water
Construction and startup of SWRA facilities have been completed and were conducted in
a manner without accidents or adverse environmental impacts. Therefore, the SWRA
satisfies the short-term effectiveness criterion.
Sediments
The selected remedies for sediments in Section 6 and Section 31 provide the greatest
short-term effectiveness for workers, the community, and the environment because these
DENlOOIS3AE.WP5
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alternatives require no disturbance of sediments. The risks from sediments in Section 6
have been addressed through construction of the SWRA and the risks from sediments in
Section 31 are within EP A's acceptable risk range. Therefore, the selected remedies
achieve protection immediately.
12.4.4 Implementability
Ground Water
The selected remedy is considered to be administratively and technically implementable.
The services and materials required to implement this remedy are readily available and
use current technologies. Construction of containment barrier walls is considered routine
and can be performed by local contractors. The effectiveness of the ground-water
treatment system has been proven by the success of the existing onsite treatment facility.
Alternatives GW-4 and GW-6 would be more difficult to implement than the selected
remedy because Alternative GW-4 would include lOO-foot deep extraction trenches that
might be difficult to construct, and Alternative GW -6 would include drilling 52 waste-pit
extraction wells that might be difficult to drill through landfill refuse.
Landiill Solids
Like the ground-water selected remedy, the landfill solids selected remedy is considered
to be administratively and technically implementable. The services and materials
required to implement this remedy are readily available and use current technologies.
The selected remedy will include excavation of drums, drum contents, and contaminated
soils using readily available construction equipment. This type of excavation is
considered routine construction, could be conducted by local contractors, and has been
implemented at other Superfund sites. Construction of the north face cover would
involve routine landfill construction procedures, and cover material is readily available
onsite.
Landf"ill Gas
The selected remedy is technically and administratively implementable. The selected
remedy will use current proven technology, and the construction of gas extraction wells
would be a routine activity that could be conducted by local contractors. In the long
term, the selected remedy would be more easily implemented than Alternatives LFG-3
and LFG-5 because construction activities would be limited to one mobilization event.
Soils and Sediments
All of the alternatives, including the selected remedies for soils and sediments, are
considered to be technically and administratively implementable.
DENlOOlS3AE.WPS
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Surface Water
The SwRA has been constructed and is operational, and has therefore been demonstrated
to be implementable.
12.4.5 Cost
Ground Water
While the selected remedy is not the least costly of the alternatives considered, it has
significant advantages over less costly alternatives. In particular, unlike those alternatives
which are significantly less expensive (Alternatives GW-l and GW-2), the selected
remedy includes the immediate design and installation of permanent containment and
collection systems on all boundaries of the Lowry Site to prevent off site migration of
contaminants. It would thus offer greater long-term effectiveness and permanence. The
selected remedy also includes toe of the landfill collection and treatment and will thus
provide greater reduction in toxicity, mobility, and volume through treatment than
Alternatives GW-l or GW-2.
Other alternatives which are only slightly less expensive than the selected remedy
(Alternatives GW-3 and GW-5) would also not include containment and collection
systems on all boundaries of the Lowry Site. The same is true of more expensive
alternatives (Alternative GW-4 and GW-6.) The addition of a multilayer cap in
Alternative GW -4 would not provide any significant advantages over the existing cap over
the landfill mass. Alternative GW-6's extraction and treatment of waste-pit liquids would
only be able to extract a small percentage of waste-pit liquids, and thus, the source of
ground-water contamination would remain.
Landiill Solids
The selected remedy is the most costly of the alternatives evaluated, but it is considered
to offer significant advantages over the other alternatives with reSPect to reduction of
toxicity, mobility, and volume through treatment and long-term effectiveness and
permanence because it would remove and treat the greatest volume of contaminated
materials in the former tire pile area, including accessible waste pits which are considered
hot spots, and would place an additional two feet of cover on the north face of the landfill
mass.
Landiill Gas
The selected remedy is more costly than the No Further Action alternative, but the No
Further Action alternative would not be effective in either the long or the short-term and
would not achieve a reduction in toxicity, mobility, or volume through treatment. The
selected remedy is only slightly more costly than Alternative LFG-3, Stage 1, but will
include the installation of a more extensive array of extraction wells around and within
the landfill and thus offers significant advantages with respect to long-term effectiveness
DENIOOIS3AE.WP5
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and permanence and reduction of toxicity, mobility, or volume through treatment. Other
landfill gas alternatives which are more expensive than the selected remedy offer no
advantages over the selected remedy.
Soils and Sediments
The selected remedy for soils and sediments is the least costly of the alternatives
considered and will also be effective in both the short and the long-term. None of the
alternatives considered included treatment.
Surface Water
The selected remedy was the only alternative considered.
12.4.6 State Acceptance
The State of Colorado concurs with the selected remedy for the Lowry Site and concurs
with the selected ARARs.
12.4.7 Community Acceptance
Based on comments to the Proposed Plan for OUs 1&6, the community and the PRPs
support the selected remedy. The community has reservations about leaving the bulk of
waste-pit liquids in place; however, it is technically infeasible to remove the waste-pit
liquids. Comments received from the community on the Proposed Plan for au s 2&3 and
4&5 were strongly supportive of the excavation and treatment of contaminated solids in
the former tire pile area. The community was also generally supportive of the simult-
aneous implementation of Stage 1 and Stage 2 gas extraction as a means of controlling
offsite landfill gas migration. However, one commenter encouraged EPA to consider the
focus of the gas extraction to be extraction and removal rather than control of offsite
landfill gas migration. The commenter felt that the additional installation of Stage 3
would yield a significant increase in the annual volume of contaminants removed for a
relatively small incremental increase in the overall cost. The community was also ada-
mantly opposed to the addition of 1.2 million cubic yards of municipal solid waste over
the former waste pits. Commenters were very supportive of EP A's decision to reject this
alternative.
Comments from the PRPs opposed EP A's preferred alternative for landfill gas and land-
fill solids and proposed a remedy consisting of land acquisition and land use restrictions
of 0.5 miles around the perimeter of the Lowry Site, enhancement of the landfill cover
through the addition of 1.2 million cubic yards of municipal solid waste, and the
installation of only Stage 1 of the gas extraction system. The PRPs' comments also
focused on the short-term effectiveness of the excavation in the former tire pile area and
the potential exposure to workers during the excavation.
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12.5 Preference for Treatment
as a Principal Element
The selected sitewide remedy includes: treatment of contaminated ground water collected
from the northern, western, eastern, and southern boundaries of the Lowry Site;
treatment of contaminated ground water collected from the toe of the landfill mass;
treatment of landfill gas collected from the perimeter of the landfill mass; and excavation
and offsite treatment of "hot spots" from the former tire pile area. The hot spots in the
former tire pile area constitute a principal threat at the Lowry Site. Also, the SWRA
utilizes treatment to control the principal threat of contaminated seepage. The statutory
preference for remedies that employ treatment as a principal element is thus at least
partially satisfied by the selected sitewide remedy.
The statutory preference for treatment will not be met for the landfill mass and associated
waste pits. Treatment is not practicable for the following reasons:
.
The large volume of waste within the landfill mass.
.
The lack of discrete, accessible hot spots that represent major sources of
contamination.
.
The impracticability of excavating and treating the entire volume of waste.
.
The prohibitive cost. Preliminary estimates during early FS studies indi-
cated that costs would be in excess of $4.5 billion.
It should be noted that the selection of a remedy based in large measure on containment
for the Lowry Site with excavation of accessible hot spots is consistent with the NCP and
EPA's guidance regarding presumptive remedies for CERCLA municipal landfill sites.
Because this remedy will result in hazardous substances remaining on the Lowry Site
above health-based levels, a review will be conducted at least every 5 years after com-
mencement of remedial action to ensure that the remedy continues to provide adequate
protection of human health and the environment.
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Section 13.0
Responsiveness Summary for Operable Units 1 & 6
-------
Section 13.0
Responsiveness Summary for Operable Units 1 & 6
This section presents the oral and written responses to comments from EP A to
individuals, concerned citizen groups, and public entities who have commented on the
Proposed Plan for au s 1 & 6. Comments are presented in italics; their responses in
plain text. Each individual or public group's comments and responses are presented as
individual subsections.
13.1 Response to
Oral Comments on the
Proposed Plan for Operable Units 1 & 6
Shallow Ground-Water and Subsurface Liquids
and
Deep Ground-Water Operable Units
Lowry Landfill Public Meeting
December 9, 1992
The following subsection is a legal transcript of the comments and responses recorded
during the public meeting held in December 1992.
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1
1
2
3
4
5
6
7
8
PUBLIC MEETING
9
LOWRY LANDFILL SUPERFUND SITE
10
Proposed Plan for Operable Unites 1 & 6:
Shallow Groundwater and Subsurface Liquids
and Deep Groundwater
11
14
December 9, 1992
7:15 p.m.
Eaglecrest High School
5100 S. Picadilly street
Aurora, Colorado
12
13
15
16
17
18
19
20
21
22
23
24
25
PAMELA MEADE COURT REPORTERS
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2
~
MARC HERMAN:
I'd like to welcome everyone
2
to the proposed planning meeting for Lowry shallow
3
groundwater and subsurface liquids and deep groundwater
4
operable units.
The purpose of the meeting is to present
5
to you, the public, EPA's preferred alternative for
remediating the groundwater operable units at Lowry
6
7
Landfill.
8
I'd like to start, first of all, by
9
providing some introductions.
My name is Marc Herman,
~o
and I am a remedial project manager on the Lowry Landfill
Superfund site Project -- not a supreme commander of
~1.
~2
allied forces.
~3
We have Robert Duprey, the director of the
~4
Hazardous Waste Management Division; Barry Levene, Chief
~5
of the North Dakota/Colorado Section of the superfund
~6
Remedial Branch; Gwen Hooten, Remedial Project Manager
~7
for the Lowry Landfill Operable Units 1. and 6; Jesse
Goldfarb, Assistant Regional Counsel; Rob Henneke,
~8
~9
Community Relations Coordinator; and representing in this
corner the State of Colorado, Colorado Department of
20
21.
Health, Angus Campbell, state Project Coordinator for
Lowry Landfill Superfund Site, Joe Vranka; State Project
22
23
Officer; Jane Mitchell, Toxicologist, Colorado Department
of Health; and Bob True, Community Relations Specialist.
24
25
We also have some other folks without
PAMELA MEADE COURT REPORTERS
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3
1
whose participation this would not be possible.
Representing EPA's technical contractor CH2M Hill, Phil
2
3
Burke, and operating the slide projector: and Andrea
Garcia, Community Relations Coordinator: and representing
4
5
the Lowry Coalition, Paul Rosasco.
6
I have a few announcements to make before
7
we get into the presentation. The last day for written
8
comments is December 30, 1992.
However, we have received
9
a request to extend the public comment period and it will
10
be extended to January 30, 1993.
11
Everyone on the mailing list will receive
12
a notice and both major newspapers in the Denver
13
metropolitan area will receive notices that they will
publish announcing the extension for the public comment
14
15
period.
16
I would request that you hold all
17
questions or comments until the end when we have a
18
designated question and answer period.
19
Can everyone hear me okay?
I would ask
20
that all commentors when you get up to ask a question or
make a comment, that you identify yourself and also
21
22
identify your affiliation.
I would ask that you please limit your
23
24
questions or comments to five minutes, and if you have
25
more than one question or comment, perhaps you could make
PAMELA MEADE COURT REPORTERS
(303) 494-2141
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4
1
tbe initial one and give someone else a chance and then
2
follow that.
3
I would remind you if you do not want to
4
make verbal comments, you can make the comments in
5
writing, and I would remind everyone that all pertinent
6
documents that were used for making this decision are
7
available for review at the Aurora Public Library and EPA
8
Superfund Records Center.
9
with that, I would like to introduce Anqus
campbell who will provide you -- oh, I'll go over the
10
11
outline first.
We've already done the introduction.
12
Angus is going to provide a history of the site.
Gwen
13
will handle the summary of site studies, and she will
14
discuss the evaluation of cleanup alternatives, and then
15
we'll talk about public comments and open up the meeting
16
to questions and answers.
17
Angus, go ahead.
18
Good evening.
I'm here
ANGUS: CAMPBELL:
19
to talk a little bit about the location and history of
20
the Lowry Landfill and some of the actions that have
taken place to date.
21
22
The landfill is located here (indicating)
23
It's
at the corner of Gun Club Road and Quincy Avenue.
24
about 15 miles to the southeast of downtown (Denver).
is about two miles east of the city of Aurora city
It
25
PAMELA MEADE COURT REPORTERS
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5
1
limits.
It's northwest of the Arapahoe Race Track and
2
northwest of the Aurora Resevoir, which is just off the
3
map here (indicating).
4
Communities in the area, there is Murphy
5
Creek Ranch two miles to the north, and Dove Hill which
6
is two miles to the south.
Eaglecrest High School is
7
about 2-1/2 miles to the southwest.
The proposed E-470
8
alignment goes, depending on which proposal you look at,
either east or west of the site.
9
10
A little more detail on the site is here,
11
again, Gun Club Road and East Quincy Avenue to the south
12
(indicating) .
The site consists -- well, the site is
13
actually part of the Denver Arapahoe Disposal Site, which
is five sections of land that was deeded to the City and
14
15
County of Denver for waste disposal practices.
I'll go
16
into that a little more later.
The Superfund site is on
17
Section 6 area (indicating).
Section 31 is the current landfill.
If
18
19 you go down Gun Club Road, that's where you see all the
20 trash. The waste pits are in the south here
21 (indicating). Unnamed Creek is a small stream in the
22 middle of the site. The tire fill area is here
23
(indicating).
24
The command post where a lot of the
activities for the Superfund studies are headed out of is
25
PAMELA MEADE COURT REPORTERS
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6
1
here (indicating), the groundwater barrier wall and the
treatment plant (indicating).
2
3
Here is a slide showing the site prior to
4
landfilling (indicating).
This is from ~956.
Here we
5
can see a good footprint of the Unnamed Creek drainage
6
system.
The actual site, again here is Gun Club Road and
7
Quincy here to the south, and you see the section line
8
here for section 6.
This is Unnamed Creek here
9
(indicating).
This is Murphy Creek, which is the major
~o
tributary that Unnamed Creek flows into.
~~
History of the Site.
Again, as I
12
indicated, the landfill area was part of the Lowry
~3
bombing range during World War II.
In 1964 that land was
14
deeded to the City and County of Denver for waste
~5
disposal practices.
Those practices went from '66 to
16
~980, and the practices were known as codisposal, which
17
was the acceptable method at the time for disposing
liquid industrial waste along with municipal solid waste.
18
19
EPA has calculated 142 million gallons of
liquid waste was disposed of into unlined trenches.
20
21
We'll have some pictures of those later.
Again, this is
22
called codisposal.
23
since 1980,
That practice ended in 1980.
24
the landfill was used for municipal solid waste only.
EPA listed the site on the NPL, National Priorities List,
25
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which is a list of the most dangerous hazardous waste
2
sites in the nation, and that's where the Superfund Site
3
funds come from.
4
In 1984 the first work began on site with
5
the negotiations on work for the groundwater barrier wall
6
and groundwater treatment facility.
In '84, '85 the EPA
7
began Phase I and II remedial investigations of the
8
site.
9
In 1988 the EPA under SARA divided the
10
site up into six operable units.
Those are Operable
11
Units 1 and 6 is what we're here for tonight, the shallow
12 groundwater surface liquids and deep groundwaters. That
13 work was conducted by the Lowry Coalition for the lUfFS
14 process. Operable Units 2 and 3 are being conducted by
15
the City and County of Denver, Waste Management of
16
Colorado and Chemical Waste Management.
operable Units 4
17
and 5, again the work is being conducted for the City and
County of Denver and Metro Waste Water Reclamation
18
19
District.
20
In December 1988 under the new Operable
21
Unit Plan, the EPA and CDR negotiated an agreement for
22
In 1989 -- we'll see later there is a
Operable Unit 1.
23
lot of tires disposed of at the site.
Denver contracted
24
with Waste Management of Colorado to shread 6 to 7
25
million tir~s on site.
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1.
In September of '89, the negotiations and
2
agreement to perform Operable units 2 and 3 and also au
No.1, and there was an administrative amendment to
3
4
include OU6 in December of that year.
In August of 1.990 section 6, the old
5
6
landfill, was closed to municipal solid waste land-
7
filling, and the cap was subsequently put on the site.
8
And in March 1.991., OUs 4 and 5 were negotiated, and in
9
August of that year, the Surface Water Removal Action was
10
negotiated.
In October of that year, the design for the
1.1.
Surface Water Removal Action began.
Tire shredding was completed 1.6 months
1.2
1.3
less than the contracted period, in April of this year,
and Surface Water Removal Action construction began in
1.4
1.5
August and, as you can see, was completed in November.
1.6
As we are here tonight the RI/FS for Operable units 1 and
6 was completed also last month.
1.7
1.8
There is a series of slides showing sort
1.9
of the progression of the landfill and waste pit
20
construction and filling.
This is the site in 1.965
21.
(indicating).
fairly long.
Some of these waste pits get rather large,
You can see a few waste pits.
They're
22
23
800 feet long and up to 300 feet wide and 30 feet deep in
spots.
24
25
This slide is from August of 1.969, and you
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can see additional waste pits being constructed.
Some
2
are up in the northern part.
3
And in '72, again, you can.see some rather
4
large features here, which are all waste disposal pits
5
for codisposal.
6
In 1977 we began to see tires being
7
disposed of here.
As you'll see later those are now
8
gone, and still we have the waste pits being constructed
9
and filled into the south into the tire area.
10
This is a picture of what codisposal is
11
and why it is listed as a Superfund site.
We have drums
12
of liquid waste disposed of in unlined pits.
These drums
13
of liquid waste were disposed of in these unlined pits.
Drums prior to 1966 were not punctured according to the
14
15
state records, and they were just disposed of in the
16
pits.
Post-1966 they were punctured and drained.
17 Also they came in tanker trucks and opened
18 up the valves of the tankers and let them go into the
19 ground into these unlined pits. And, again, here we can
20
see the tire piles here (indicating) and all the landfill
21 and waste pit areas here, and this is how it was done.
22 This is a good picture of what codisposal
23 is. Again, we have a pit here, 30 feet deep, fairly
24
large, about two-thirds full of liquid.
It was backed up
25
-- trucks and waste haulers backed up and just dumped
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their solid wastes into the liquid waste.
2
The theory behind it was that the solid
waste would act as an absorbent and sop up -- similar to
3
4
what a sponge does -- sop up the liquids.
Just to give
5
you an idea, 77 pits have been identified on site, and 53
6
of those pits have known liquid in them.
7
To give you a scope of what these are,
8
generally a Superfund site would be one of these pits,
and here we have 50 of them, if it was elsewhere in the
9
10
nation.
11
Contents of the waste pits, again it's 142
million gallons, give or take a few, of industrial and
12
13
municipal liquid and solid waste, including sewage
14
sludge, metal plating wastes, petroleum derived products
15
and waste products, pesticides, industrial solvents.
16
These unlined pits over time leaked, and
17
to address that shallow contamination, several interim
18
remedial actions were put in place.
We have the
19
underground barrier wall -- I'll show you a slide of that
later -- the groundwater treatment facility, the Surface
20
21
Water Removal Action, and other actions, the shredding of
the tires on site that allowed for access to the other
22
23
RI/FS activities.
24
Here's a cross-section of the existing
25
groundwater barrier wall (indicating).
It was built,
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1
again, in 1984. It's about 960 feet long, 30 feet wide
2
and 35 feet deep, and that's made of compacted clay, and
on the upgrading side is a French drain or gravel drain
3
4
that -- there is a pump in it which collects the
5
contaminated groundwater and pumps it to the treatment
6
plant.
7
Here's a picture of the treatment plant --
8
or what it used to look like (indicating).
It's been
9
updated tremendously since then.
The process used for
10
treating the contaminated groundwater is essentially
11
filtration, air-stripping -- this is the old airstripper
12
(indicating), a carbon unit, which takes up a lot of the
13
volatile and semivolatile organic compounds, and then
14
that clean water which meets standard is injected
15
downqradient of the barrier wall in what is known as the
16
injection trench.
I believe the volume is on the order
17
of 10 gallons a minute on the average.
18
Here's a picture of the Unnamed Creek as
19
it used to look several years ago.
Again we have
20
contaminated seepage and groundwater flowing to the
21
Here are tire piles.
This was the problem that
north.
22
the Surface Water Removal Action was trying to address.
What happened is that when it would rain, precipitation
23
24
would go into this Unnamed Creek and flow offsite, this
25
contaminated surface water.
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The Surface Water Removal Action is here
2
in green (indicating) and essentially is a drainage
blanket that collects the contaminated seepage and keeps
3
4
it separate from the rain water and precipitation.
Again, we have a cartoon of the waste pits, the old tire
5
6
pile areas and command post and groundwater treatment
facilities here.
7
8
Tire piles.
This is an old slide of what
9
the tire piles used to look like.
I believe it was 35
10
acres were shredded over a period of 16 months, I
11
believe, and they are put into -- this is the shredding
12
operation -- put into a monofill of 3 acres.
The size of
13
shreds are about 2 inches square, thereabouts.
14
This is a lined monofill and contains
15
nothing but tire shreds.
These shreds have been used as
16
some of the drainage material for the Surface Water
17
Removal Action.
In addition the Colorado Department of
18
Highways has used it as a low density fill over some
ironically other landfills they're building a highway
19
20
over, and in addition about 20 percent of the shreds have
ended up as a fuel supplement used in cement kilns.
21
22
And with that I'll allow Gwen to discuss
23
OUs 1 and 6.
24
GWEN HOOTEN:
I'm not as loud as Angus.
25
I'll have to use a microphone.
I'd like to extend a
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special welcome to our students in the back.
We're glad
2
to see you here.
3
As part of the site summary, Angus has
4
discussed with you the first portion.
What I'd like to
5
do is place special emphasis on what we're here to
6
discuss tonight which is DUs 1 and 6.
7
About 1989 we looked into -- previous to
8
that we were doing an EPA fund project, which means that
9
we financed the studies.
Between 1989 and 1990, we moved
10
into what we refer to as an enforcement, which means that
11
the potentially responsible parties, or otherwise known
12
as the polluters, paid for the expense of the studies.
13
These studies, which we will refer to as
14
additional site characterization, the treatability
15
studies and feasibility studies, were done simultaneously
16
so that the work could be completed expeditiously.
17
We are at the end of the feasibility
18
study, and we're here tonight to discuss the proposed
19
In addition to that, we have other studies going
plan.
20
on simultaneously.
We have DUs 2 and 3 on which the
21
remedial investigation feasibility studies are being
22
We expect that to be completed -- well, it
It has been accelerated up until April or
conducted.
23
was August.
24
May of this year.
In addition we have DUs 4 and 5.
We
25
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expect that to be completed in March of '93.
We're
2
looking at proposed plans coming out shortly after those
3
feasibility studies are completed, and then we expect to
write a site-wide Record of Decision.
4
5
As far as the results of the studies, what
we found is that the groundwater predominantly flows to
6
7
the north.
However, there is a component to the east and
8
to the west.
9
This right here (indicating) is a
10
cross-section of the site, and what we're showing here is
11
what our definition of shallow groundwater is versus deep
12
groundwater.
What we have here is -- this is south and
13
this is north, and this is the groundwater containment
14
system that Angus campbell talked about, and we have
15
refuse to the south, here we have alluvial soils and more
16
refuse with lesser waste pits to the north.
17
Operable Unit 1, which is shallow
18
groundwater, is defined by the weathered and unweathered
19
This right here is termed as the separation
Dawson.
20
layer, and below that is considered the deep
21
groundwater.
50 the deep groundwater includes the lower
22
Dawson, the Denver and all other aquifers underneath
there.
23
24
For the horizontal extent of
25
contamination, what we found is that the waste pits seep
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out into the groundwater surrounding them and the extent
2
of the contamination really flows around where the
majority of the waste pits are, and, again, the flow is
3
4
to the north so we see a migration pathway.
For the vertical extent of contamination,
5
6
primarily that is driven into the deep groundwater by a
7
well that we refer to as B-504.
We've also placed C-702
8
in here because we do have one hit of benzene.
9
With this what we wanted to demonstrate to
10
you is what the extent of contamination is thus far.
11
This well is located about 150 feet from surface.
This
12
one here is about 170 feet.
Again, there is the barrier
13
wall (indicating).
14
What we believe is of most concern to you
15
and to us is the protection of human health and the
16
environment.
In order to determine that, we have to
17
determine what the risk is.
We believe that this graphic
18
demonstrates that.
19
First of all, we have to have a
20
contaminant source.
By the sampling that we've done, we
21
know we have contaminants out there.
Then you have to
22 have a transport, a point of exposure, a way that that
23 exposure has a route to a receptor, and then what you are
24 drinking or inhaling or touching has to have a toxicity
25
value.
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We have to have all of these components
2
before we can say there is risk.
A baseline risk
3
assessment is a study that describes the potential risks
4
posed to human health if nothing is done to remediate the
risk.
5
6
Angus Campbell has talked to you about the
7
interim remedial actions that we've had done in coopera-
tion with the PRPs to ensure that the contaminants have
8
9
not migrated off site.
10
If we were to do a baseline risk
11
assessment, we would allow those to deteriorate.
We
12
would essentially walk away from the site.
Then we're
13
trying to determine what the risk is to those remaininq
if we were to walk away from the site.
14
15
So for the results of our groundwater, we
16
supplied to you an aerial photo of the site.
This riqht
17
here is Section 6 (indicating).
As you can see, there is
18
little to no development at this present time around the
19
site.
Therefore, we do not believe there is a receptor,
20
so there is no current risk.
21
Right here is one of the nearest
~2
developments, as well as Murphy Ranch, and then also Dove
23
Hill.
24
What we're finding is that if you built a
residence on the site and you did drink water there, you
25
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would have a 1 in 100 chance of getting cancer above what
2
you are normally exposed to, and this graphic shows that
3
you would then be a receptor.
4
Now, we'll go into the evaluation of the
5
cleanup alternative itself.
In order to do this, we
6 ended up having to look at very many technologies that
7 would address the type of contaminants that we found.
8 Since we found volatiles, semi-volatiles, metals,
9
pesticides, we looked at a number of different ways to
10
treat them.
We then screened those into treatment
11
options and set up treatment trains to do the complexity
12
of the contaminants that we found.
13
We further honed those down to remedial
14
action alternatives.
I should tell you right now at this
15
point in the presentation that the remedial action
16
alternatives that we looked at are primarily containment:
17
that is because the Lowry Landfill is about 400 acres.
A
18
large portion of that has been landfilled.
We have about
19
70 to 100 foot of depth of refuge.
20
We at one time did consider taking 85
percent of the landfill and incinerating it, excavating
21
22
the refuge and then incinerating.
The cost of doing that
23
particular remediation ran to $4.5 billion, and that is
the estimate that most of you probably read in the
24
25
papers.
We have discounted that remedy for
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prq.cticability.
2
80 today what we'll be discussing is all
3
the alternatives as well as the EPA preferred
4
alternative.
5
In order to evaluate these alternatives,
6
we looked at what we refer to as nine criteria.
The last
7
two criteria, state acceptance and community acceptance,
8
will not be determined until after the comment period for
9
the proposed plan.
Based upon the comments that you
10
supply to us, we will be able to gauge community
11
acceptance of the alternatives.
The first two criteria are ones that have
12
13
to be met for all the alternatives before we are able to
14
select one.
These are overall protection of human health
15
and environment in compliance with applicable or relevant
and appropriate requirements.
16
17
The next five are referred to as balancing
18
criteria.
In this we have the short-term effectiveness,
19
which may be the risks that we may expose workers to
during the implementation of the remedy: the long-term
20
21
effectiveness and permanence, the ability we're able to
reduce the risk irreversibly: reduction of toxicity
22
23
mobility and volume through treatment: the
implementability: and then finally the cost.
24
25
Now, again, our baseline risk assessment
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1
is based upon no action, we walk away from the site.
If
2
we were to do that, what we found is that there would be
contaminants moving off site to the north, and there
3
4
would be the component to both the east and the west.
5
We also looked at the vertical movement of
6
contaminated groundwater in 200 years.
These migration
7
pathways are primarily coming from the feasibility study,
a groundwater model that we completed.
8
9
In this, if the barrier wall was allowed
10
to deteriorate, we would see groundwater migrating to the
11
north.
In addition, we would see some migration
12
vertically.
13
In Alternative 1, we had referred to this
14
one as the no further action alternative, meaning that we
allow the interim remedial measures we had taken
15
16
previously to be the remedy.
This is the existing
17
groundwater barrier wall and the associated treatment
18
plant, the Surface Water Removal Action.
19
In addition to that, we would incorporate
20
Waste Management's soil cover, which is a 4-foot clay,
21
which is 2 feet above and beyond what the Colorado
Department of Health regulations for landfill closures
22
23
requires, and then we would monitor to ensure the
24
contaminants did not leave the site.
25
50 these are the common features.
In
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aqdition to that, there would be a contingency plan for
2
vertical migration.
We wouldn't allow the model solely
3
to be our prediction of whether or not contamiriants would
4
migrate vertically.
We would monitor to ensure that it
5
did not reach the lignite bed.
6
Alternative 2, we have again the common
7
features, the barrier wall, Surface Water Removal Action,
8
the landfill cover, and in addition to that, we would put
9
a 2,200-foot groundwater extraction trench.
This would
10
be at a cost of $36 million.
11
Alternative No.3 would again have the
12
common components, but in addition to this we would put
13
what we refer to as a toe drain, a groundwater extraction
14
system that would be closer to the majority of the waste
15
pits on the south side.
With this we are assuming that
16
the groundwater -- and have studies that demonstrate this
17
-- is more contaminated than the groundwater that flows
18
to this wall.
So, therefore, we would be constructinq a
19
new plant that would take care of the contaminants.
20
Alternative No.4 has again the common
elements with a toe drain and an up-gradient containment
21
22
collection and/or diversion water that would divert clean
water from the south away from the site so it would not
23
24
mix with the contaminated water.
This barrier wall would
25
be at a depth of approximately 100 feet and is included
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1
in this cost.
2
In addition to that we would put a multi-
3
layer cap to increase -- decrease the infiltration.
This
4
overall cost is $101 million.
5
Alternative 5, we have the common
6
components, a toe drain, again with its associated
7
treatment plant, and we have a barrier wall to take care
8
of those components of flow on both the east and the
9
west. This would be at a cost of $59 million.
10
And our final alternative is Alternative
11
It has the common components again, a toe drain, and
6.
12
then here we would place extraction wells.
The graphic
13
shows it as symmetrical, but we would try to put these
14
extraction wells in the waste pits that we believe were
15
This would be done at a cost of $66 million.
pumpable.
16
After looking at these alternatives, the
EPA determined that Alternative 5 was one that we wished
17
18
to modify.
Alternative 5 is one of the only alternatives
19
that does take care of the east and west components of
20
groundwater flow.
50 the way that we modified is that we
21
22
looked at adding a barrier wall to the south so that we
23
could divert clean groundwater from the south away and
24
thereby reduce the volume that would have to be treated.
25
This is the alternative that we are introducing to you as
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our preferred alternative.
2
The reason that we're recommending this is
3
because it meets all of the EPA cleanup criteria.
It
4
provides control of off-site migration to both the east
5
and the west.
It reduces toxicity, mobility, and volume
6
of the contaminated water through collection, treatment,
7
and diversion.
Water is collected at both the north, at
8
the toe of this landfill, and also on the east and west.
9
In addition, it would be diverted from the south, thereby
reducing the overall volume.
10
11
We believe it's more protective of the
12
human health and environment through long-term
13
effectiveness and permanence.
Once we do treat it, we
14
believe there is a permanent reduction of risk.
In
15
addition to that, we believe we are taking care of the
16
east and west groundwater flow patterns.
We know that it's using proven technology
17
18
that is implementable and that it can be easily
19
And the cost is relatively similar to or
constructed.
20
less than other alternatives.
21
In addition to the criteria, we also
22
looked at CERCLA statutory requirements.
We felt that we
23
are meeting our preference for treatment, that
we are reducing the volume and the toxicity and the
24
25
mobility of the constituents.
We also believe that we
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are treating and that we have not looked at the least
2
favorable alternative, which is to take the contaminants
3
off site.
4
We also believe that we are using a
5
permanent solution on the east and west as opposed to
6
allowing it to migrate there and then doing something.
7
With this, Marc Herman is going to be our
8
moderator for the questions and answers, and I'm going to
9
go ahead and turn it over to him.
10
After the public comment
MARC HERMAN:
11
period and responding to comments to this proposed plan,
12
the EPA, in consultation with the Colodado Department of
Health and in cooperation with potential responsible
13
14
parties, will be conducting remedial investigation
15
studies and will finalize feasibility studies for both
the landfill solids and gas operable units and for the
16
17
soils and surface water and sediment operable units, and
18
we will then issue proposed plans for OU's 2 and 3 and 4
19
and 5, and finally we will issue a site-wide Record of
Decision that will take into account all public comments
20
21
from all the proposed plans.
22
FOllowing a record of decision, remedial
23
design negotiations will begin and hopefully conclude in
our lifetimes, and we will hopefully then be able to
24
25
design -- actually design the final remedies for the site
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clean-up and get around to constructing those remedies.
2
For your written comments, you are
3
requested to send those comments to Gwen at the address
on the screen, u.s. Environmental Protection Agency, Mail
4
5
8 HWM-SR, that stands for Hazardous Waste Management
Superfund Remedial, 999 - 18th Street, Suite 2500,
6
7
Denver, Coiorado 80202-2466.
Again, I would request that when you have
8
9
a question or comment, please identify yourself and your
affiliation and to limit your comment or question to five
10
11
minutes, please.
12
SPEAKER:
I'm a high school teacher in
13
Littleton.
I have students who are kind of interested in
14
this whole public process.
You mentioned the possibility of vertical
15
16
migration further down than might be expected for these
17
barriers.
What sort of contingency plans do you have for
18
that vertical migration?
19
The question is:
What are
MARC HERMAN:
20
the contingency plans for potential vertical migration of
contaminated groundwater?
21
22
What we have is a
GWEN HOOTEN:
23
groundwater model that was performed, and we looked at
24
periods up to 200 years.
And what our groundwater model
25
shows -- which we don't consider the groundwater model
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the answer but it's a relative answer -- it showed that
2
we have vertical migration but it does not reach the
3
lignite bed, which is approximately 350 feet below the
4
surface.
So we do have a vertical migration component.
5
We will monitor and assess some actions to
6
be taken should we see vertical migration to that lignite
7
bed, but at this time we feel fairly confident that the
8
migration is fairly slow, and we're hoping that we can
take care of contamination while it's in the shallower
9
10
part of the aquifer.
11
MARC HERMAN:
We forgot to point out that
12
along the wall are cartoons of all the alternatives that
13
were evaluated in case you want to take a look at them a
14
little closer.
15
SPEAKER:
I'm from Thunderbird Home
16
Association across the street at Gunclub Road and
17
We're on wells there.
Alameda.
18
How far north have your test sites gone
19
and how deep?
We draw on wells anywhere from 700 to 1000
20
feet in that area.
21
Your question is:
How far
MARC HERMAN:
22 north has the groundwater contamination been identified
23 or how far have our studies gone?
24 SPEAKER: I've seen you test wells around
25 your area. But how far north have the test wells gone?
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26
1
GWEN HOOTEN:
Perhaps we misled you a
2
little bit.
Our baseline risk assessment is based upon
3
the interim remedial measures not working~
What we found
4
is that we have tested all the wells in the local area,
including the area that you're talking about, and we have
5
6
not found contamination to the north.
7
Phil, did you want to say anything more
8
about that?
9
PHIL BURRE:
In 1985 we conducted tests of
10
selected holes in the north area there, and there was no
11
contamination found in any of those wells.
To date, no
12
groundwater contamination has migrated past the barrier
13
wall that you saw, the red line.
14
SPEAKER:
I realize the groundwater -- and
15
we're talking about the aquifer which is, I think, a
16
little faster flowing.
I know in '85 one well was
17
tested because his water was getting funny looking and
18
brown.
Nobody ever contacted any of the homeowners
19
associations.
Has anything been done since '85?
20
Since '85 numerous wells have
PHIL BURKE:
21
been sampled on the site to the north.
We have been
22
monitoring those wells for almost eight years now, deep
wells and shallow wells both, and to date there is no
23
24
contamination migration on site.
Even though your home-
25
owner wells to the north haven't been sampled, plenty of
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1
wells have on site, both shallow and deep.
2
SPEAKER:
If you want a sample, you can
3
use mine.
4
SPEAKER:
Rick Shalene associated with
5
Lowry Landfill.
6
Gwen, can you give us some detail of what
7
sort of actions you might request under this alternative
if, in fact, you find some contamination in your
8
9
monitoring down the road?
10
Well, Rick, we're talking
GWEN HOOTEN:
11
horizontal contamination, and we believe ~ternative 5,
12
our modified 5, takes care of any migration to both the
13
east and west today if it was implemented.
If you're talking about a vertical
14
15
migration, then we would have to institute some actions,
16
and right now we don't know what those actions will be.
17
But if I was to speculate, I would say that we would
probably use extraction of the contaminants, if they
18
19
started to get down near that lignite bed.
20
The alternative doesn't go into
SPEAKER:
21
any of that detail.
22
We were at one time
GWEN HOOTEN:
No.
23
looking at horizontal wells placed at lOO-foot spacings
throughout the length of the landfill, and what we're
24
25
finding on Lowry is that we have what is termed as dense
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1
aqueous phased liquids.
We don't believe that we will have much
2
3
success in pulling those out, and we also believe that
the vertical migration will be somewhat limited due to
4
5
the tight formation.
6
So with those in mind, we have not come up
7
with a vertical migration remedy.
We would look to try
8
to do as much as we can using the horizontal collection
9
of groundwater and hope that that does it.
10
SPEAKER:
Do you have any financial
11
contingency in this plan should you detect contamination
in some of the monitoring wells?
12
13
GWEN HOOTEN:
Although the cost estimates
14
you saw did not have amounts -- and, Paul, I'll need you
15
on this one.
The estimates that you saw tonight do not
16
have a financial amount for the vertical contingency
17
plan.
However, we will be writing it into our Record of
18
Decision, and we will hold the potentially responsible
responsible for any migration to that lignite
19 parties
20 bed.
21
22 Paul?
23
Is there anything you want to add to that,
PAUL ROSASCO:
We did a lot of analysis,
24
and because, as Gwen indicated, we have very low
25
permeability, we have very low rates of flow.
The
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1
estimate was it was going to take over 300 years for it
2
to get to the first unit that we could pump the water
3
out.
Coal type bed about 8 feet
That's the lignite bed.
4
thick down about 300, 350 feet.
5
When you look at what it would cost 300
6
years from now to build a system and you bring it back to
7
today's dollars and say, "Okay, let's put some money in
8
for financial insurance," it's a minimal amount of money.
9
It takes very little money to, say, put in 50 extraction
10
wells 350 years from now.
11
So we did analyze that and look at that
12
from a financial impact, but the estimates say it's going
13
to take 300 to 600 years for the groundwater to reach
that depth, and that's the first level at which we could
14
15
pump any of the liquids out.
16
My name is Bob Falcon.
I'm an
SPEAKER:
17
officer in a recycling company and also I'm an engineer.
I'm not sure I like at all any sort of containment, much
less the modified containment, because I think all you're
18
19
20
going to be doing is delaying the problem, and you're
21
feeding the public possibly being assured that you're
going to be properly monitoring for 200 years.
22
23
I have noticed that the EPA has funded
24
grants and research into soil washing, and it seems to me
25
that at least some portion of the surface, say, 10 feet
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1
tG 30 feet, could be soiled washed and at least some of
2
the organics taken out and disposed of properly by the
same technology that made them in the first place.
3
4
And so that's -- my first question is:
5
Have you done anything with soil washing, and if so, does
6
it apply to the Lowry site as part of -- at least part of
the modified plan?
7
8
Also under your modified plan, what is
9
your intention for the use of the surface for, say, the
10
next 200 years?
Would you make it a park or wildlife
11
refuge, or is it just to sit there as a great big
containment facility waiting for whatever might or might
12
13
not happen?
14
Have you considered purchase of the
surrounding land to make it part of an overall use, and
15
16
are the polluters paying for whatever these millions of
17
dollars are?
Who pays for these modified plans?
18
MARC HERMAN:
Those are all excellent
19
questions.
First of all, let me remind you that this
20
proposed plan is for the shallow groundwater subsurface
21
liquids and deep groundwater operable units.
I don't
22
know that specifically soil washing is being investigated
under the other operable units, but that -- it is being
23
24
investigated under the soil surface water and sediment's
25
operable units along with other technologies, and there
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1
are also technologies being looked at, potentially
digging up some of the contaminated soil in the landfill
:2
3
solids operable units remedies possibilities.
4
So those are being investigated and a
similar sort of meeting will be held to propose to you
5
6
what we think are reasonable alternatives for those
7
environmental media.
8
SPEAKER:
So they could retroactively
9
apply for this plan?
10
MARC HERMAN:
There are six environmental
11
media broken up into six operable units, and what we
12
strived to do is to take alternatives from each of the
13
operable units and have them blend together to be one
14
cohesive remedy for the site.
So in addition to controlling and treating
15
16
groundwater, we will be looking at treating or digging up
17
whatever soils and sediments there are, and we will be
18
looking at landfill gas and landfill solids in terms of
19
what technologies are available and meet the nine
20
criteria to clean up the site.
You asked about land use, and we could
21
22
spend an entire evening talking about land use, but I
23
will tell you there is a Southeast Area Planning
Initiative going on right now, and that is a group of
24
25
local governmental entities that have been meeting now
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1
fQr a while -- about four months.
We're talking about
2
the City of Aurora and Arapahoe County and City and
3
county of Denver and many other landowners, large
landowners, both state and local within the area.
4
5
And what they're doing is, they're making
a plan for land use for that entire eastern portion of
6
7
the Denver Metro area, and Lowry Landfill Superfund site
8
is one part of that.
So the possible land uses and land
9
use restrictions for the area are being investigated
10
right now.
And EPA intends to incorporate the
11
recommendations and decisions of the Southeast Area
12
Planning Initiative group into our final proposed
13
site-wide remedy-
14
And then there was another question.
15
Cost.
Who's paying?
SPEAKER:
16
MARC HERMAN:
That's an excellent
17
question, and that's what I wanted to emphasize.
The
18
remedial investigation and feasibility studies that are
going on are being paid by private entities, potentially
19
20
responsible parties, who have been identified as being
responsible for either transporting or generating the
21
22
waste or operating the site, and they perform the studies
under the watchful eye of the EPA and the Colorado
23
24
Department of Health.
25
Do those who are paying the cost
SPEAKER:
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1
weigh into the decision for anyone of these plans?
Do
2
they have input to say, "Well, we like 3~ million better
than we like 6~ million?
3
4
In that respect they are the
MARC HERMAN:
5
public just like you are.
They are allowed to provide
6
their comments to the proposed plans.
7
So how much comment was in the
SPEAKER:
8
choice?
9
MARC HERMAN:
We'll find out.
We're in
10
the public comment period right now.
And that will be public information.
EPA
11
12
will collect all the comments, either from a private
13
company or an individual, and we will summarize the
14
comments, respond to them, and provide those to everyone
15
who is interested.
16
I was just wondering if
SPEAKER:
17
Alternative 5, how long would it take to complete the
18
whole process?
19
That's a good question.
The
MARC HERMAN:
20
question is:
How long would it take to implement this
21
proposed remedy?
22
We're talking about
GWEN HOOTEN:
23
approximately three years to implement.
That includes
24
But let me talk to you a little about the
design time.
25
process.
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1
Once the EPA writes a Record of Decision,
2
then we enter into negotiations for the remedial design
3
and the remedial action of that Record of Decision.
That
4
normally can take about six months to do that.
Then after that the PRPs, or those that
5
6
signed up to do the remedial design and remedial action,
we have an estimate that it will take approximately three
7
8
years to complete the design and start implementation of
the action itself.
9
10
SPEAKER:
I'm from Littleton High School
11
and I was wondering -- you stated that one of the nine
12
criteria was short-term, and I was wondering what that
13
risk would be to the workers in Alternative 51
14
We were cueing our
GWEN HOOTEN:
15
toxicologists down here to see if they wanted to
16
respond.
17
But we believe that OSHA will protect the
18
workers from any short-term effects.
OSHA has
19
regulations that talk about protection levels that the
20
workers must be in -- masks so they don't inhale, suits
so they don't have any dermal contact, those kind of
21
22
thinqs.
23
We believe they can be protected during
construction if they comply with the OSHA standards.
24
25
Rebecca wild of Lowry Landfill.
SPEAKER:
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1
What about the people off site, the people who live and
work around the Lowry Landfill during th.e cleanup
2
3
proceedings and decontamination?
4
The question is:
What sort
MARC HERMAN:
5
of health risks are posed in the short-term to
individuals or the public living off site away from the
6
7
cleanup activities?
8
GWEN HOOTEN:
We, again, believe that the
9
-- any disturbance of the soil, any inhalation factors,
10
the dermal factors will be pretty much confined to the
11
site construction.
We're not looking at any kind of
12
alternative or the components of the remedy that we
13
believe would enhance either the inhalation exposure or
14
the dermal exposure for anybody off site.
15
You mentioned a
SPEAKER:
Mary Lake.
16
4-foot clay cover for the landfill mass.
I've been here
17
since '77 and was part of CALL when it began.
My
18
question is:
How much clay was protecting when it broke
19
open one summer where it rained and it was dry and rained
20
and it was dry, and it broke open and it smelled to high
21
heaven allover this area.
Was there 4 foot of clay
22
then?
23
When was it?
That was
ANGUS CAMPBELL:
24
early '80?
25
SPEAKER:
I can't tell you the year.
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1
ANGUS CAMPBELL:
There was 1-foot cover
2
over the landfill at that time.
If it was prior to 1980,
3
they would have daily cover, so it was less than that 1
foot. So the answer is no, there was not that 4-foot
4
5
cover as there is on site now.
6
SPEAKER:
You started breaking into this.
7
We get a day like today when we have high pollution and
8
high winds.
Who is going to tell the people living in
9
the near subdivisions that what they're breathing is
10
okay?
Who's going to monitor that?
OSHA is not.
11
ANGUS CAMPBELL:
The State Health
12
Department Air Program will be monitoring.
They will
13
have to have a monitoring plan that will be part of the
14
remedy to ensure that the standards that are in place for
15
the metro area are met at the site boundary.
16
Where would those testing
SPEAKER:
17
stations be?
18
They will probably be at
ANGUS CAMPBELL:
19
the corners of the landfill mass and at the construction
20
site too, because they have to have monitoring -- air
monitoring on site for health and safety purposes.
21
22
So there will be probably two stages of
monitoring, the worker monitoring and ambient air
23
24
montoring.
25
We have some experts in the
MARC HERMAN:
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1
crowd who can corroborate.
As part of the Surface Water
2
Removal Action, construction of the collection system in
3
Unnamed Creek, the entities, Waste Management of
4
colorado, who constructed the collection system, took
great pains to make sure there was monitoring programs
5
6
both around the construction and on the boundaries of the
7
landfill site to do what you're asking, to monitor
8
potential impacts-- or a potential impact on air
9
contamination.
10
So that's sort of like a small glimpse of
11
what we may look at down the line in the larger scheme of
12
things.
13
Rick?
14
SPEAKER:
What kind of standards are we
15
looking at for that type of monitoring?
What are the
16
existing standards that have to be met?
17
ANGUS CAMPBELL:
The process will be that
18
we will go through and look at the contaminants of
19
concern that have been identified in the risk assessment
20
They will use the state standards
and to set standards.
21
and go through a state standard setting procedure on a
site by site basis.
22
23
This will emulate a state permitting
24
issue.
It won't get a State permit just because it's a
25
Superfund site, but it will have to meet all the
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1
requirements.
And if I'm in charge, then I will make
2
sure that will happen.
3
MARC HERMAN:
You want to know specific
4
air regulations?
5
SPEAKER:
Yeah.
6
ANGUS CAMPBELL:
It will be Regulation 7
7
and 8 and 3.
8
SPEAKER:
The reason I'm asking, it's been
9
some time since I looked, but the last time I looked at
10
the Colorado standards, they were pretty lax and almost
11
nonexistent.
12
ANGUS CAMPBELL:
I don't know when the
13
last time was you looked at it, but with the new Clean
14
Air Act that was passed in Congress last fall, I believe,
15
all those will come down to the State as well.
16
The Denver area is fairly stringent in
17
what they allow to be permitted from a stationary source,
18
and that's what the landfill will be.
19
Well, with regard to
SPEAKER:
20
particulates.
What about volatiles?
21
ANGUS CAMPBELL:
The State of
22
Massachusetts has set ambient air limits that will be
23
used for our initial evaluation for safe levels at the
24
site boundary.
25
The nonattainment area has been extended
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1
over the metropolitan area.
That means that there is no
2
allowable release of volatile or organic compounds within
that nonattainment area.
3
4
If you care to know more, feel free to
give me a call, and I can help you when I have the
5
6
appropriate documents in front of me, or I can direct you
7
to somebody who has a little more expertise in our air
8 program.
9
10 liability.
SPEAKER:
My question now is regarding
Can you name specifically by name who are the
11
polluters who paid for the studies?
12
Remedial investigation
MARC HERMAN:
13
studies?
14
In other words, who gave
SPEAKER:
Yes.
15
the EPA money?
Do they still have the liability when the
16
EPA is done here, or does the Colorado Department of
17
Health have the liability if the monitoring system goes
18
Where is the liability located for 200 years?
awry?
19
I'm going to ask some of the
GWEN HOOTEN:
20
coalition members to help me out here.
But the folks
21
that are paying for the studies for the shallow
groundwater and the deep groundwater were at one time 14
22
23
I'm going to attempt to name the 14
Adolph Coors, Conoco, Syntex Chemical, Gates
companies.
24
companies:
25 Rubber Company, Littleton/Englewood Bi-City Treatment
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Plant, the City of Lakewood, Metro Waste Water
Reclamation District, IBM, Shattock, Honeywell and
2
3
Sunstrand and Hewlett Packard -- and we got Amax.
4
Is that ~4?
And Asamera oil.
5
Is that ~4?
6
7 escaped?
8
9 answer.
SPEAKER:
The City and County of Denver
GWEN HOOTEN:
No.
Let me complete the
That was for the study on the shallow
10
groundwater and deep water that you're seeing and we're
11
discussing tonight.
In addition to that, we have four
12
other operable units being studied under two different
13
orders.
14
Under the OU' s 2 and 3 order, we have City
15
and County of Denver, Waste Management of Colorado, and
16
Chemical Waste Management, and they are paying for that
17
study.
18
Then for the last two operable units,
Operable Units 4 and 5, we have again the City and county
19
20
of Denver and Metro Waste Water Reclamation District
21
financing those studies.
22
Now at the end of this process, we have
23
identified over 275 potentially responsible parties.
considers their liability joint and severable, so we
EPA
24
25
could bill anyone of those 275 parties for the total
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1
bill.
So they're all liable.
2
SPEAKER:
If the plan is approved and
3
implemented, they still retain liability?
4
MARC HERMAN:
Correct.
5
I was just going to say if anybody was
6
wondering why we call it a toe drain, it's because it's
7
at the base or the foot of the landfill mass, and what do
8
you have at the end of a foot -- toes.
In this case just
9
one.
10
SPEAKER:
Could you explain a little bit
11
more exactly what a toe drain is?
12
MARC HERMAN:
It will be a -- well, you
13
guys did the work on it.
Paul, do you want to explain
14
this one?
15
The question is exactly what is a toe
16
drain or what is a groundwater collection drain?
17
PAUL ROSASCO:
It will either be a series
18
of extraction wells will be installed at close spacing at
19
the foot of the landfill, at the toe, to collect all of
20
the water that otherwise would flow out into the creek or
21
north through the site, or it might be a trench that is
dug and filled with a pipe and gravel and a pump that's
22
23
put into that to pump the water out of the trench.
24
Either one of the those options were
25
looked at and considered valid for future construction.
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SPEAKER:
What if it gets clogged up like
2
the barrier wall in the past?
3
PAUL ROSASCO:
I'm not aware that the
4
barrier wall got clogged up, but the wall itself.
That
5
may have been some issues involving the treatment plant.
6
SPEAKER:
But the internal --
7
PAUL ROSASCO:
The wells would have to be
8
replaced, and that was included in the cost of the
remedy, the cost for either rehabilitating the wells
9
10
using standard well techniques to remove iron or actually
11
replace the wells.
But those costs were included in the
12
remedy.
The same with the drain, come in and
13
rehabilitate it, remove iron or replace portions of it.
14
I'm Ellen Fulton, a senior at
SPEAKER:
15
Littleton High School.
After your plan is implemented,
16
would any of the three of you feel safe buying a home
there and raising a family next to the site?
17
18
Excellent question.
I'm
MARC HERMAN:
19
going to let Gwen answer that.
20
I live about two miles to
GWEN HOOTEN:
21
the west of the site, and I do have a family and I'm
trying to raise her.
22
23
I'm saying
SPEAKER:
This i$ for Angus.
24
this with a smile on my face, but 10 or 11 years ago
Chemical Waste, the County; everybody, called this a
25
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1
sanitary landfill, harmless.
codisposal?
When did it become a
2
3
I think since it began.
ANGUS CAMPBELL:
4
A sanitary landfill refers to the covering of trash on a
5
periodic basis.
And it may not have been daily, however,
6
it was covered up unlike an open dump.
It was prior to a
7
sanitary landfill, you had a dump and you go out there in
8
the back 40.
9
SPEAKER:
This was referred to at the
10
Governor's Monitoring Committee meetings, and every
11
meeting I attended it was always the sanitary landfill.
12
I notice in actuality you were calling it --
13
ANGUS CAMPBELL:
Codisposal.
14
SPEAKER:
It was never called that.
15
ANGUS CAMPBELL:
Codisposal was the
16
process employed.
sanitary landfill.
It was a process employed at the
17
Does that help?
18
That helps.
SPEAKER:
19
I have concerns with the
SPEAKER:
20
environment.
I'm wondering with the environment in 100
21
years who is to say you're going to be around to clean it
22
This project seems to be incomplete, if you
up again?
23
have to do more work in 300 years on it.
Do you see what
24
I'm saying?
25
The question
MARC HERMAN:
Yes, I do.
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is:
Are any of us going to be around 300 years or
2
whatever from now to make sure that the remedy is
3
implemented properly?
4
I know I won't be around.
5
GWEN HOOTEN:
That is a good question, and
6
that's the reason that we think Modified 5 is the best
7
one, because it takes care of the east and west
8
components now even though from a modeling effort we
9
don't believe it's contaminated -- the contaminants have
10
not migrated that far.
11
As far as the vertical contaminants, we
12
have discussed with you the technical and practicability
we have today, but the EPA as a general practice will
13
14
revisit Superfund sites every five years.
In that
15
five-year review, we go through all the standards that
are looked at, we look for any changes in the state of
16
17
the art on the sampling techniques, and we look for any
changes in the techniques we have available for
18
19
clean-up.
20
So even though we don't have the
21
technology today, perhaps we will have it in the future.
But we don't have the answers today.
22
23
I want to just point out and
MARC HERMAN:
24
remind everybody while the private companies or the
municipalities that are involved in this project bear the
25
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1
burden of liability, as everybody might suspect, it
eventually gets passed on to either the consumer or the
2
3
taxpayer.
So we all share in the liability eventually.
4
You didn't answer my question of
SPEAKER:
5
the role of the Colorado Department of Health.
You
6
monitor every five years, but the Department of Health at
7
least has some control or jurisdiction over that site on
8
a daily basis for the next 300 years, if the State is
9
here.
10
MARC HERMAN:
On a daily basis?
11
Isn't the Colorado Department of
SPEAKER:
12
Health ultimately responsible for the safety and health
13
of the citizens, and, therefore, ultimately responsible
14
for the control of this site?
15
MARC HERMAN:
That's why --
16
So when you're gone and come
SPEAKER:
17
back in five years and test, during that time doesn't the
18
Department of Health do something?
19
MARC HERMAN:
That's why they're a partner
20
with the EPA on this site, but I'll let Angus answer.
21
What is their role?
SPEAKER:
22
What is our role?
In the
ANGUS CAMPBELL:
23
Now, on the site
Superfund we are management assistants.
24
itself it has to comply with State solid waste rules and
regulations as well as with the air pollution rules and
25
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regulations as I mentioned earlier.
It will be an ongoing process.
We have
2
3
standards that have to be met at the site, and we will
4
ensure that those are met by the owner and operator.
5
PHIL BURKE:
It probably should be made
6
clear that the testing isn't every five years.
In fact,
7
the testing may be many times in a single year.
It's
8
every five years that the EPA comes back and evaluates
the site as a whole, but all throughout the remediation
9
10
the site is tested and monitored.
11
We won't make a decision and
MARC HERMAN:
12
walk away and come back in five years.
13
My question is:
How much,
SPEAKER:
14
approximately, of the waste do you plan to treat?
15
GWEN HOOTEN:
And we have Paul Rosasco
16
here to answer that question.
17
Modified Alternative 5
PAUL ROSASCO:
18
treats approximately 7 -- it will take out, our estimate
19
was, 700 pounds of the actual chemicals on an annual
20
basis over the life of the remedy.
It takes out a lot of
21
groundwater but the actual concentration in the
22
groundwater is very low.
It's on the order of parts per
23
million.
So you treat a lot of groundwater to get a
24
pound out, but we will take about 700 pounds of the
chemicals out a year.
25
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SPEAKER:
What's the rate?
2
PAUL ROSASCO:
The flow rates for the
3
system were -- we have approximately 12 gallons a minute
currently on the existing groundwater barrier treatment
4
5
system.
There is an additional several gallons a minute
6
from the approximately 10 gallons from the landfill toe
7
drain and approximately there is an adjustment of a few
8
gallons per minute on the east and west, so the total
9
flow estimated is 20 gallons a minute we would be taking
10
out of the site.
11
SPEAKER:
What's the total amount that is
12
being taken out, how many gallons?
13
It's 20 gallons a minute.
PAUL ROSASCO:
14
How many in the entire landfill?
SPEAKER:
15
Several hundred million
PAUL ROSASCO:
16
gallons in the landfill.
17
What is the regional flow across
SPEAKER:
18
the landfill in terms of gallons?
19
PAUL ROSASCO: The regional flow across the
20
site is approximately -- essentially the 20 gallons a
21
minute. We're taking out everything that would flow to
the north of the site that would have the. contamination,
22
23
collecting all of that.
24
MARC HERMAN:
I don't know how many of
25
those 142 million gallons is waste.
I understand each
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1
gallon has a different part per million, but the bottom
line is how many of the 142 million gallons of waste are
2
3
actually going to be clean?
4
GWEN HOOTEN:
If we're treating 20 gallons
5
a minute on an eight-hour-a-day basis -- I'll speculate
6
on eight.
Paul is telling me that we want to get into 24
7
hours a day.
Okay, let's go with 24 hours.
If we're going to treat 20 gallons per
8
9
minute, 60 minutes in an hour, 24 hours a day, 365 days a
10
year, whatever that number comes out with is the amount
11
of gallons that we're going to treat in a year.
expect to be out there at a minimum of 30 years.
Our
We
12
13
cost estimates have all the estimates based upon 30
14
years.
15
So I don't have a number for you.
We
16
could punch it out real quick and find out what it would
17
be.
Does that answer your question?
18
It clarifies it at least.
SPEAKER:
19
Your question was with
ANGUS CAMPBELL:
20
regards to the liquids disposed of in the waste pits.
Those liquids are in the waste pits and are seeping into
21
22
the groundwater, so you're having a dramatic increase in
23
Does that help
the volume of water that's contaminated.
24
too?
25
And this diluted contaminated groundwater
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is what is being collected and treated.
2
I don't know if this is
SPEAKER:
3
answered.
What is the stuff that's been treated?
Where
4
does it go?
5
Good question.
Right now
MARC HERMAN:
6
contaminated groundwater is treated at the City and
7
county of Denver's water treatment plant which is on site
8
and all the contaminants are removed, and the water is
9
discharged back into the ground north of the treatment
10
plant and north of Lowry Landfill.
11
What will be the stuff that's
SPEAKER:
12
used to decontaminate?
Is that waste too?
13
The carbon absorption units
MARC HERMAN:
14 that Angus Campbell talked about collects the
15 contaminants. They can be taken and cleaned. They never
16 go away is the problem. We just move it from one place
17 to another presumably. The carbon units can be thermally
18 regenerated. The contaminants are burned off.
19 SPEAKER: My name is Eric Knight, and I go
20 to Littleton High School. I was wondering why has this
21
been discussed recently rather than years or months ago,
22
if it's such a threat to the community?
23
MARC HERMAN:
It has been.
There are
24
people here in the crowd who remember back in the late
25
'70s.
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SPEAKER:
I'd like to tell you that we
2
have a number of people here tonight who have been
3
working on this issue for almost 13 years.
4
MARC HERMAN:
It's a great question.
Let
5
me mention to you that we have copies of proposed plans,
6
and we have copies of progress updates down in the front
to keep abreast of what's going on with the progess, and
7
8
you can get on the mailing list, and we'll mail you all
the updates and the proposed plans that we issue so you
9
10
can keep more informed on this.
11
SPEAKER:
Two-part question.
I'm Terry
12
Horn with the citizens for the Responsible Development of
13
Has the E-470 Authority asked for your input
E-470.
14
environmentally on which would be the better route for
the routes they have out there; and No. 2, is the EPA in
agreement with the E-470 Authority that there should be
no need for an environmental impact statement to be
15
16
17
18
produced along this area, a couple hundred feet of your
landfill east or west?
19
20
Well, first of all, I think
MARC HERMAN:
21
that -- Carol, can you help out?
Is part of the
22
southeast area issue part of the E-470 been involved?
23
CAROL MCLENNAN:
We haven't gotten
24
specific comments from the Authority in response to that
question. The Authority certainly has access to all the
25
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1
information, and I'm sure they will be commenting.
2
GWEN HOOTEN:
The Environmental Protection
3
Agency does not advise government groups as to their land
4
plan.
What we try and do is protect human health and the
5
environment on Superfund sites.
So we would not be in
6 the position to instruct the E-470 Authority.
7 However, they have contacted both EPA and
8 the Colorado Department of Health. They have been
9
interested in what is happening on section 6, the
10
Superfund site.
11
Does that help answer your question?
12
SPEAKER:
Yes.
Thank you.
13
I was just wondering, on TV you
SPEAKER:
14
see other states bring in waste to this landfill, or are
15
we the only ones in Colorado.
Is this like a major
16
landfill or whatever -- or that's what I heard.
17
This was a regional landfill
HARC HERMAN:
18
when it was in operation during the periods '66 to '80.
19
You may be thinking of
ANGUS CAMPBELL:
20
the Highway 36 Hazardous Waste Landfill out of Last
Chance. That's a regionwide Subtitle C landfill.
21
22
MARC HERMAN:
Under the Resource
23
Conservation Recovery Act, which is a different law that
24
EPA administers, that law applies to active hazardous
25
The Comprehensive Environmental Response
waste sites.
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compensation and Liability Act, CERCLA, or Superfund,
2
takes care of abandoned or old hazardous waste sites.
3
SPEAKER:
This would be a basic political
4
question.
You mentioned all the companies that were
5
paying for some of the studies that were done, and I
assume paying the salaries for some of the people who did
6
7
these studies and came up with this particular plan.
8
It also seemed like in today's paper or
9
the other day's paper there was an article on the total
cost and who pays for it, and they had listed again
10
11
Hewlett Packard, Honeywell, Gates, Adolf Coors,
Littleton/Englewood Treatment, et cetera.
12
13
I guess my question is:
If that's the
14
bill, 120 million, they paid their portion, are they then
finished with this deal, their responsibility?
15
16
ANGUS CAMPBELL:
I gave that quote to the
17
paper.
The reporter asked me what was a ballpark figure.
18
I went through the analysis that the groundwater is
probably the most expensive remedy at the site, and I
19
20
said, "Well, go ahead and just double it.
It's probably
21
in the ballpark."
That's where that came from.
22
Now, with respect to the rest of that,
I'll have to let Gwen answer that.
23
24
GWEN HOOTEN:
We haven't publically
25
released an overall ballpark figure so that's why the
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facts are misquoted in the paper as EPA saying that.
2
It's a headline.
SPEAKER:
3
Yes, I'm aware of that.
GWEN HOOTEN:
4
As far as your question -- and I'm going
5
to repeat it back to you so I heard it right.
You're
6
saying that politically are the potentially responsible
parties paying for both the RI/FS and the remedial design
7
8
and the remedial action, and did I hear also perhaps our
9
oversite cost -- the EPA and the Colorado Department of
10
Health?
11
SPEAKER:
Is there a political motivation
12 to choosing this solution -- perhaps of its cost and ease
13 of implementation? And once it's done, does it get those
14 organizations who are paying for it off the hook?
15
Well, Superfund liability,
GWEN HOOTEN:
16
as many of the PRPs can attest to, it's very difficult to
17
Even when we implement the remedy of
get off the hook.
18
which the PRPs would pay for, our five-year reviews
19
really extend their liability to anything that we would
find.
20
21
So their liability is pretty much until
22
the site is delisted or until the site is removed from
23
the National Priorities List and we no longer feel that
24
there is a risk.
25
I think the second part of your question
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-- was there a second part?
The political motivation for
2
picking one alternative over another?
3
SPEAKER:
I'm trying to see if there
Yes.
4
is a tie-in between the groups who paid for the studies,
the groups that will have to pay for the clean-up, and
5
6
perhaps the people paying the salaries of the people
7
coming for the five-year review?
8
GWEN HOOTEN:
We are going to invite our
9
divisional director to answer this question.
10
BOB DUPREY:
I'm not political.
Let me
11
try to answer that.
I think it's a good question.
12
Because since some of the responsible parties produced
13
the technical work, what I'm hearing is then who
influenced us on selecting a particular remedy because we
14
15
have less trouble with the cost and so on.
16
And the answer is no, in my view, that we
17
were looking for -- and, frankly, I think some of the
18
larger responsible parties are looking for -- as
19
permanent a solution as they can get.
Because they don't
20
want to come back and face the continuing liability that
21
remains there if other costs or problems arise in the
22
future.
It's like they would like to pay their costs and
23 get out.
24 So in our view we picked the one that was
25 actually towards the higher end of the cost range with
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1
additional measures of protection.
Even where it didn't
2
show much migration, we decided to go ahead with some
3
measures to fully contain the site to not allow moisture
4
to get into it as much as we could prevent moisture from
5
getting in and to draw down the water and contamination
6
level as much as we can with the treatment system and the
7
draw-down system that has been proposed.
8
So if we could have done more than that
9
and if people have ideas how to increase the
10
effectiveness of that, we certainly welcome that.
We
11
haven't made a final decision.
This is a proposed plan,
12
so we want to take more comment where we can be more
13
effective and more permanent on the answer.
14
On the liability question, I want to
15
answer that a little bit because there is major
16
litigation currently going on on this issue in Federal
17
District Court before Judge Finesilver, and the very
issue you've raised is the subject of that lawsuit; that
18
19
is, who will pay what share of these costs ultimately.
I believe that ultimately this will either
20
21
get decided in the course of that litigation or through
22
settlement talks that are taking place among the
23
different parties.
24
The assurance I can give you is that the
25
Federal Government and the State Government are looking
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1
to. have all the costs paid by the responsible parties and
all the continuing costs that might occur be paid by the
2
3
responsible parties.
4
SPEAKER:
First of all, who owns this part
5
of the land that we're talking about?
Second, the liable
6
companies, what are they doing with their current waste?
7
They must be recycling or putting it into a standard
8
center to have it looked after.
And, third, the large
9
companies are playing politics because they have been
10
dumping their stuff allover the United States and half
11
the time around the world.
They don't want the other
12
sites found, so they're going to comply to bury this and
13
hide instead of looking into technical recycling to clean
14
the mess up that they caused.
15
MARC HERMAN:
To answer your first
16
question, ownership of the land, the City and County of
17
Denver owns the land.
The answer to your second
18
question, where does the hazardous waste that was dumped
19
into Lowry Landfill go or similar sort of waste go now,
and they go to authorized hazardous waste disposal sites.
20
21
I'm
SPEAKER:
I have just two comments.
22
Chuck Barrett, a private consultant.
23
Number one, a question about the
If everYthing that was dumped out at this
24
liability.
25
site was done according to the rules and regulations at
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the time, the cost associated with the dumping of the
2
waste at that time, and the Federal Government came back
3
in hindsight and said, "You did something wrong in
4
today's standards from 20 years ago."
50 I foresee the federal regulations will
5
6
always say that if they have to come back and clean up
the site 20 years from now, the potentially responsible
7
8
parties will be the ones to talk with, but ultimately it
9
will be the taxpayers and consumers that are going to pay
10
for it.
If you buy Coors beer, they will roll the cost
11
of that onto it.
12
Your observation is a lie.
SPEAKER:
13
The other issue is that I think
SPEAKER:
14
there was a question whether they were actually cleaning
15
up this 142 million gallons, and my understanding is
you're not cleaning up any of the 142 million gallons
16
17
except that which seeps into the rain water that falls on
18
the site and comes down to the collection basin.
And the
19
reason why you'll be there for several hundred years is
20
the fact that the amount that will be dissolved in any
21
given time is a relatively minute amount.
50 if you take your 20 gallons a minute
22
23
and multiple it out by the hours per year by the 30 years
24
and you come up with a number in excess of 142 million,
25
but you still have got some of the contamination still
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entrenched in the soil.
2
MARC HERMAN:
Actually the liquid
3
hazardous waste has comingled with the groundwater on
4
site and that's under the ground, and the purpose of this
5
proposed plan is to collect that contaminated
6
groundwater.
There is an action going on right now
7
that's designed to effectively -- while we study the
site, to effectively collect the contaminated groundwater
8
9
and to treat it.
10
And that's also the purpose -- to address
11
your question of rain water, that's the purpose of the
landfill cap, to prevent more moisture from entering the
12
13
site and seeping down and mixing with the hazardous
14
waste.
15
SPEAKER:
After your proposed plan, your
16
No.5 -- in 1984 you said we were the most hazardous
17
site.
After your plan, where will we be be on this
18
scale.
19
We were not the most but
MARC HERMAN:
20
one of the many.
That's a good question.
Is that a
21
political question?
Maybe Bob will answer that.
22
BOB DUPREY:
Well, it's one of the 1200
23
some -- 1250 or something like that on the National
24
Priorities List sites across the nation.
There is some
25
15 of those here in Colorado.
We didn't give it a
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relative priority, and I can't remember quite where it
2
is.
I think somewhere in the middle.
3
Basically we will go through a process
4
after we have done at least one of the five-year reviews
5
to see how effective this remedy is after it's been
6
selected to ultimately delist it from that priorities
list if the dangers are adequately taken care of.
7
8
There is a process that's gone through to
9
actually remove it from the priorities list.
That
10
doesn't mean that the work won't continue to go on.
All
11
that still will be mandated what we'll put into effect
12
and that will be a court ordered remedy.
It's required
13
to be entered before a Federal District Court, and it
14
will be enforceable then and the Federal District Court
15
will have continuing jurisdiction over that.
16
SPEAKER:
How does your plan solve your
17
need -- toxic waste?
18
Are you talking about the
GWEN HOOTEN:
19
nine criteria?
How does our plan solve the environmental
20
issue of cleaning up the site?
We believe that our remedy is a
21
22
containment remedy, but we are also collecting and
23
treating groundwater as both the existing barrier wall,
24
the toe drain, and the east and west components.
50 we
25
believe that we are treating groundwater and that we are
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reducing the overall risk.
But we don't have a time frame when there
2
3
will be no risk.
We
We don't know when that will"be.
4
expect to be out there a long time treating the waste.
5
MARC HERMAN:
Do you mean how will that
6
accomplish our goal, the EPA mission, to protect human
health and the environment?
7
8
GWEN HOOTEN:
Did we answer your
9
question?
10
SPEAKER:
I guess.
11
SPEAKER:
I'm a student.
I was wondering,
12
all this stuff is fine and good, but what are you going
to do with the other landfills to keep this problem from
13
14
happening again?
How do we make it so we don't have to
15
clean it up?
16
BOB DUPREY:
It covers other programs
17
other than the Superfund programs.
That is the most
18
important question, I think, because we don't know how to
19
fully solve this problem.
If we knew how to do it in a
20
way in which we could get rid all of what was put in
21
there and the haphazardous way it was done.
It's mixed
22
in with soils and garbage.
We can't extract effectively
23
all those contaminants in a way that's quick and
efficient and cost effective.
24
25
Back in 1980 Congress authorized what is
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1
called the Resource Conservation and Recovery Act.
Rules
2
were put in effect that would not allow practices to take
3
place, and since that date those practices have not taken
4
place.
5
There was an attempt out at this very
6
landfill to put in a hazardous waste site during that
7
period and it was done early without all the safeguards.
And, frankly, through the action of Paul, I remember the
8
9
activity, they had that stopped and we made Chemical
10
Waste Management remove that soil and send all that waste
11
out of this area.
It was all sent to approved facilities
12
that met the standards.
13
Those facilities now require, first of
14
all, that the waste be treated to meet certain treatment
15
standards and also requires that no liquid waste be put
16
in the ground.
And there
It has to be all solidified.
17
are liners required, a double lined system, where you
18
have leach checks which monitor those constantly.
If you
19
have a problem, to correct it.
20
So we have in place today, and have for a
21
number of years, requirements that prevent this kind of
22
situation from happening again.
If it happens, it
23
happens because it's an illegal practice.
We go in and
24
use our enforcement authority to correct it.
25
MARC HERMAN:
I just want to mention again
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tQat Gwen and I and Angus are very interested in hearing
anybody's concerns and comments, and if you don't get
2
3
your questions answered tonight, I want to volunteer our
4
phone numbers.
Please feel free to call us and ask us
5
questions.
We can provide you with information.
6
Angus' phone number is 692-2385.
Gwen's
7
phone number is 293-1533.
And my phone number is
8
293-1625.
9
SPEAKER:
I'm wondering about the
10
environment and the animals, like the animals around the
11
landfill.
On this paper here there is two landfills
12
probably not three miles apart from each other.
Is this
13
pushing the animals away from there?
14
Part of our duty is to
MARC HERMAN:
15
protect human health and the environment.
Included in
16
the environment are the wildlife.
And as part of the
17
feasibility studies and the remedial investigations for
Superfund sites, we look not only at the threats to human
18
19
health, but we also look at the impact to vegetation and
also wildlife.
20
21
So I guess what I'm recommending is that
if you would like to, you could probably get more detail
22
23
on how we address the issues of wildlife or the
24
environment in some of the documents we produced.
25
You can get those, again, at the Aurora
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Public Library or the EPA Superfund Center..
2
We do have our toxicologist
GWEN HOOTEN:
3
here from CH2M Hill, Beth Hudson, and as part of the
4
studies for the operable units, we have done an
5
ecological study.
6
Beth, if you would come up and discuss a
7
little bit the results of that.
8
BETH HUDSON:
As part of the risk
9
assessment for Operable Units 4, 5, and 2 and 3, that's
10
the surface water sediment, surface soils, landfill gas,
and landfill solids, EPA looked at the aquatic and
11
12
terrestial habitat at the facility within Section 6,
13
looked for evidence for the presence of threatened or
14
endangered species, also looked at information about the
15
indigenous wildlife in the area, for example, the
16
prong-horned mule deer, some of the smaller animals,
17
mice.
Also it looked at some of the vegetation patterns.
18
The ecological risk assessments are quite
19
a bit different than human health in that it's a new
20
science and that it's very difficult to quantify the
21
impacts in terms of risk to those receptors.
The overall
22
ecological assessment indicates that there could be
23
adverse impacts to receptors impacted by surface water
24
sediment and surface soil.
But beyond identifying the
25
chemicals that could cause impact, it's difficult to
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ch~acterize exactly what those impacts are.
I hope that answers your question.
2
3
SPEAKER:
summarizing all the various
4
alternatives that exist on site land and use restrictions
5
that will continue, can you tell us what those
6
restrictions are and what the EPA and the state foresee
7
happening during the clean-up period and after, off site?
8
GWEN HOOTEN:
The existing institutional
9
controls that we are talking about are -- the landfill is
an operating landfill, and as such they have restricted
10
11
access through the use of fences, and they have a gate
12
that is monitored for any access.
50 that's one form of
13
institutional control.
14
In addition to that, the Mayor of Denver
15
has an Executive Order No. 97 that restricts the land use
16
of Section 6.
17
We will look towards the Southeast Plan
18
Initiative Group to tell us any additional institutional
19
controls that they may institute.
But those are the ones
20
we're referring to in our document.
21
So you don't foresee any active
SPEAKER:
22
land use, industrial use, or anything like that on that
site in the future?
23
24
GWEN HOOTEN:
Not in the near future.
25
When we did our baseline risk assessment, we did assume
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that a residence will be built on the site.
So we have
2
not defined what future or just how soon that will
3
happen.
4
But our risk assessment is based upon a
5
residence, but we don't expect any residences to be built
6
during the term that it's going to be cleaned up.
7
ANGUS CAMPBELL:
I would like to add
8
something just as an example.
In any institutional
9
controls measure taken on any Superfund site, permanance
10
is something that we evaluate very strongly -- how that
11
control is in place and how permanent is that control.
12
And when you're talking land use plans, over time those
13
change.
14
Could I add to also since
BOB DUPREY:
15
this was also a garbage landfill, the idea of actually
putting residents there or structures is not advisable
16
17
because the gases will build up from the decomposition of
18
the garbage, and as a general rule there will be
permanent restrictions I believe that Aurora, Denver will
19
20
want to see in terms of actually having structures on a
21
garbage landfill.
That's not from the hazardous waste.
22
That's from the ordinary paper and solid wastes in
23
there.
24
So from a practical standpoint, we are
25
going to look and see some very strong restrictions on
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development on the site itself, and those will need to be
built into the final decision and become enforceable but
2
3
will be there for the future so people won't --" they
won't forget over time this is there and they
4
5
accidentally build on top, which in the past where people
have done it in other places, it has created major
6
7
problems.
8
SPEAKER:
I was wondering after the
9
contaminants are extracted from the groundwater, where
10 will they be
11 made?
12
13 removed from
disposed of and what provisions will be
MR. HERMAN:
If the contaminants are
14
the groundwater through use of carbon
absorption units, the granulated carbon pulls the
15
contaminants out.
I indicated earlier that the carbon
16
can be thermally regenerated and burn the contaminants
17
off.
18
In other cases the contaminants, if
19
they're accumulated, will have to be disposed of in
20
compliance with the Resource Conservation and Recovery
21 Act, which is the set of laws and regulations that
22 dictate how hazardous wastes currently can be disposed of
23 properly.
24
I can clear that a little bit
BOB DUPREY:
25
There are companies in the United states -- there
more.
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are several of them, one is Calgon, who have as part of
2
their business the destruction of these chemicals that
3
are collected in their activated carbon cells -- just one
of the companies.
4
5
But whoever is selected ultimately to do
6
this work, and that's yet to be done, we will make sure
7
that there is a process to monitor where that collected
8
waste goes, how it's disposed of, and to ensure it's not
9
released at a future date back into the environment.
10
That will be a part of this process.
11
But the best method in my view is
12
activated carbon, because there you're going to get
13
destruction of the chemical, and that carbon can then be.
14
brought back to the site and reused over and over again.
15
So that has special advantage.
It really
16
depends on the particular technique.
Sometimes you end
17
up with a bunch of sludge so that you have no other
choice but to go back to another landfill with that.
In
18
19
that instance it has to be an approved hazardous waste
20
facility that is properly designed and monitored.
21
In burning those taxies off of
SPEAKER:
22
the carbon, when you release that into the air, does that
impact the environment?
23
24
BOB DUPREY:
That's not the way it works.
25
It has an extremely high performance efficiency and only
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vo!atiles are collected in an activated carbon system.
2
Those are combustible.
It's done at very high
3
temperatures and under strict conditions.
4
The air standards that apply to that are
5
very strict so only a tiny, tiny amount of what was
6
originally in there could possibly be released back into
7
the environment.
8
SPEAI
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1
it would be that additional chance of contracting cancer.
2
The national overall average
MARC HERMAN:
3
for anybody to contract cancer is one in four.
So Gwen
4
was saying above and beyond the national average.
5
SPEAKER :
But to drink it for whatever
6
period -- not just a cup of water.
7
GWEN HOOTEN:
This is based upon on a lot
8
of assumptions, the body weight of the person, how much
9
they're drinking a day, how many days in a year they're
10
drinking it, how many years they're drinking it.
11
It's based upon a lot of assumptions, and
12
EPA makes what we determine as a reasonable maximum
13
So we look at the upper limits of all those to
exposure.
14
determine what the risk would be.
So we feel it's fairly
15
conservative.
16
SPEAKER:
What would that risk decrease to
17
after this project is finished?
What would be the
18
difference?
19
GWEN HOOTEN:
We would try for that risk
20
Whether or not that's technically
to go down to zero.
21
practical, we're saying right now that we can't achieve
22
that at this time.
That's why it's a containment type
23
remedy.
24
I would like to add one
BOB DUPREY:
25
There are three or four questions that I'm
thing.
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sensing you're not really getting clear.
2
On the first point, I've been here in the
3
area since 1979, and I've been involved with the site,
particularly early on, very extensively with some of the
4
5
difficult problems.
But one of the things that was done
6
quite early was to put in that barrier wall and treatment
7
system on flow to the north.
And since that time there
8
has been no detection of any off-site contamination from
9
this site, and we've gone a long time, approximately a
10
decade, now.
11
And part of the reason it's taken so long
12
to get to this point where we decided some of the
13
ultimate things to do is because we made a commitment to
14
Aurora and a number of people to look at as much
treatment as we could do at this site and not simply just
15
16
putting a cap on.
We tried to put in as much as we can.
17
But also because there were a lot of
18
unanswered questions.
There has been an enormous amount
19
of studies and monitoring, and that's taken a lot of
time, but what it does give us is a great deal of
20
21
assurance that there is no off-site movement of
22
contamination, and that under this remedy there will be
no off-site movement of contamination.
23
24
And if we're wrong -- and I think some of
the best minds in the state are working on this from the
25
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companies involved as well as from the governmental
agencies and the consultants that are here -- we'll have
2
3
to go back and fix that.
4
And if you have some ideas -- as I say,
5
this meeting in large part is to try and find out if
6
there is something that's been missed.
And if there is
7
something we can improve on and how we can do that, what
8
further things could be done?
9
We're very open to changes.
This isn't
10
the answer.
We are required by law to respond to the
11
public's input and the technical input we receive.
So if
12
there are things we can do better, let us know and we'll
13
try to do them.
14
You indicated" the three-year
SPEAKER:
15
period for implementation of the plan.
Is that three
16
years from the beginning of construction or end of
17
construction and actually in operation?
18
That's a great question.
MARC HERMAN:
19
That was the period for
PAUL ROSASCO:
20
doing all the design and the actual construction of the
21
50 it would be fully operable at that point,
remedy.
22
including initial testing and shake down and so forth.
23
SPEAKER:
Are you saying that the EPA or
24
the hazardous waste technology does not exist to pump one
25
or more of the existing ponds of what's in there now and
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take it to a hazardous waste site and have it processed
2
of these 142 million gallons?
Does that not exist?
3
GWEN HOOTEN:
I'm going to let Paul follow
4
up on my answer.
5
In short, we're not saying that.
We're
6
saying that anything is pumpable.
I mean if we apply as
7
many dollars as possible, anYthing is possible for
8
pumpability.
But we're not convinced that we'll be able
9
to pullout all the contaminants.
The dense aqueous
10
phased liquids we do believe will probably still be
11
confined to that area.
12
We're saying that given the pumping rates
13
that we have experienced at that landfill due to its
14
tight formation, that we will gain as much by having it
15
gradually migrate to these points of collection as we
would gain from spending money to pump it.
16
17
Paul, is there anYthing you want to add to
18
that?
19
Earlier on in the process
PAUL ROSASCO:
20
we looked at alternatives that would try to accomplish
21
exactly what you're asking.
One of them looked at an
22
alternative where we had 800 wells out there pumping.
It
23
still took 200 years to get even a significant amount of
24
the contamination out of the site, because we put in a
25
number of wells into these pits to try and pump the
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liquids, and we only get very, very small amounts.
2
If you think back to the photos that they
3
showed, we had all kinds of materials, a lot of sludges
4
in there with the wells you just can't get a lot of
liquid out of there.
5
6
The pond and groundwaters down
SPEAKER:
7
below and the big ion exchange column, once you get all
8
the way down to the bottom, it may be benzene or thiozene
9
or some aromatic, which then you process.
But in each
10
strata there may be PCBs or something else that you're
11
just keeping.
You're using the ground as just a great
12
big ion exchange.
13
We did tests to try and
PAUL ROSASCO:
14
look and see if we could get to different fractions, if
15
there were fractions present.
We tried all of those
16
things.
We set treatment plants out at the site to do
17
exactly what you're asking.
We still cannot get a lot of
18
liquid out of the site.
The garbage did absorb a lot.
19
The soils are very tight.
And what we get out is. not
20
It's mixed with leaching from the
those separate cases.
21
refuse and other things, so we have to treat all of
22
that.
23
We looked at biological treatment systems
24
that totally destroy the chemicals, totally break them
25
down, running them on site and still we were looking at
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hund~eds of years to even make a dent in this.
2
So that's why we made the conclusion to
3
look at these types of remedies.
SPEAKER: The 142 million gallons doesn't
4
5
exist except in a mix, soil mix and garbage?
6
BOB DUPREY:
I think some of your
7
questions are some of the same ones I asked and went to
8
this analysis of all these alternatives.
If you look at
9
Alternative 6 over here on the wall, you see all the well
10
points.
That's one of the ones that was to do part of
11
what you're talking about, even though there were others
12
that were more extensive.
13
The difference in the amount pulled out
14
was inconsequential in my view.
But the other point that
15
was persuasive to me, and it's one if you have some ideas
16
which you think we should sift through, was those well
17
points are all going to create potential vents to the
18
atmosphere.
And what was said way back in '79, '80 and
19
'81 when we had some problems with the odorous nature of
20
this material, it's vile, because I smelled it too.
I
21
remember it well.
22
We were concerned that this would create a
23
pathway to the air that might create more problems than
this small amount of additional treatment that we would
24
25
get out of it versus the toe system that would be put
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in.
2
But it is a complex technical question.
We were seeking exactly what you're stati~g we ought to
3
4
do, and we just simply felt that remedy was not as good
as the other one and would offer some additional risk.
5
6
SPEAKER:
Thank goodness you didn't try
7
pond creek.
8
BOB DUPREY:
I'm familiar with that too.
9
SPEAKER:
You had mentioned some
10
radioactivity material, right, on the 142 million
11
gallons?
12
We are finding some
GWEN HOOTEN:
Yes.
13
radionuclides out there.
For the most part we believe
14
that they're naturally occurring.
We have not looked at
15
the radionuclides specifically because we're looking at
16
all media.
17
We plan to release a risk assessment for
18
the radionuclides' portion.
19
SPEAKER :
But that can't be cleaned up by
20
carbon?
21
In the treatability studies
GWEN HOOTEN:
22
that were conducted, we didn't really have that many
23
radionuclides.
There wasn't that much in the residue.
24
50 the treatment studies didn't bear out some of the
25
sampling that we found.
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SPEAKER:
What will go downstream of the
2
pond could be found anywhere in Colorado or anywhere in
the world by parts per million?
3
4
GWEN HOOTEN:
Yes, that's what we're
5
finding.
6
SPEAKER:
On your map you have the
7
groundwater extraction trench.
What is that exactly?
I
8
know what your toe barrier is because I've seen that.
9
MARC HERMAN:
The barrier wall?
10
SPEAKER:
What is that extraction
Yes.
11
trench?
12
MARC HERMAN:
The barrier wall is like an
13
underground dam.
14
SPEAKER:
I know what that is.
On some of
15
your maps you have the new wall which is quite large.
16
PAUL ROSASCO:
If you remember the slide
17
that Angus showed that showed what the groundwater
18
barrier wall looks like.
There is a gravel drain on one
19
side and clay.
The extraction trench would be either the
20
gravel portion or be a series of wells running along that
alignment to collect the liquids.
21
22
I thought the concern with
SPEAKER:
23
putting that along the south end was that by digging the
trench you create a pathway for more water to come in
24
25
really than you would be taking out.
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When did the decision -- how did that come
2
about that you decided to add that to Alternative 5?
3
The barrier wall on the
MARC HERMAN:
4
south?
5
SPEAKER:
Yes.
6
GWEN HOOTEN:
Charlie, I'm unaware of what
7
you're talking about.
8
SPEAKER:
If you look at 5, you don't have
9
an intercept.
If you try
I heard where the concern was.
10 to dig down on the south end, because the soil was so
11 tight and there was very little seepage coming in that
12 you could break that up and actually allow additional
13 seepage to come in by putting in that kind of a facility.
14
GWEN HOOTEN:
Perhaps you're talking about
15
the toe drain.
16
SPEAKER:
That's why it wasn't included in
17
the original 5 I thought.
18
PAUL ROSASCO:
Charlie, I think there was
19
a discussion earlier on about the toe drain being a lot
20
deeper and a lot more extensive.
And what that was, when
21
we looked at the chemical data, we would be taking a lot
22
of clean water at depth and with this other water than we
23
would be taking out in the process.
What we do is make the gradient, that is
24
25
the pressure that's driving the groundwater, make it
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st~onger to drive it down deeper.
2
So we decid~d not to build the deeper
3
drain at the landfill but to build the shallower one so
4
we did not aggravate the problem.
5
BOB DUPREY:
One of the concerns I had was
6
to try to prevent as much moisture from getting into the
system as possible and then drain it as much as possible
7
8
over time so you draw down the level and you take away
9
the drainage for any vertical movement.
Even though it was a small flow in, we
10
11
thought with a modified, not the original, plan that
12
would actually create that conduit that we're talking
13
about.
We could divert some water, and that any water
14
that could be diverted out of the system would in the
15
long term, over hundreds of years, be a benefit.
That
16
was the reason for the addition.
17
If there are other concerns that -- or
18
problems created here where we shouldn't do that,
obviously we reduce the cost somewhat, and it would be
19
20
that much easier to implement.
That's something we would
21
want to know from the community-
The intent was to create as much as
22
23
possible the situation where the cell out there would be
contained fully on all sides, and that the drainage site
24
25
would be a full collection treatment.
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What were the comparisons of
SPEAKER:
2
contaminated radionuclides to uncontaminated ground
3
during construction and the rupturing of any of these
wells having more seepage in the water?
4
5
I'm going to answer your
GWEN HOOTEN:
6
second question first.
There is always the potential for
7
a well to become environmentally unsound for some reason.
8
It could be the seasonal changes or what-not.
And we
9
would look during the operation and maintenance to ensure
10
the soundness of all the wells.
That is something we
11
would look at.
12
And once we found that a well was possibly
13
environmentally unsound or that it was causing cross
14
contamination, we would abandon the well.
15
with respect to your first question which
had to do with radionuclides, would you repeat that.
16
17
If you were to take a sample of
SPEAKER:
18
the radionuclides in the contaminated ground and compare
19
that to uncontaminated ground off site, what would the
20
comparison be?
21
We're findir.g that the
GWEN HOOTEN:
22
comparison would be quite similar, that the radionuclides
23
that we're experiencing on site are comparable to the
24
background radionuclides.
25
There was some question as to whether or
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not we had transuranic radionuclides, which is man-made
2
nuclides, and we're finding for the most part that the
3
data that we've collected is inconclusive, and we really
cannot say whether it's there or it's not there.
4
5
SPEAKER:
One of the questions that I do
6
recall coming up when we were discussing the containment
7
system concerns whether or not there was actually space
to install without getting into private land.
8
9
Could you elaborate on the proposed
10
location of the barrier wall.
11
The alternatives where there
GWEN HOOTEN:
12
was some practicability problem was Alternative 4.
south barrier wall was at a depth of 100 feet.
That
13
14
Alternative 5 the barrier wall is at a depth of 50 feet.
15
We believe it's totally impracticable.
We
16
don't believe there is the need to access land that's not
17
presently owned by the City and County of Denver to
implement that.
18
19
Any other questions?
This
MARC HERMAN:
20
is not the only opportunity.
before.
I think I mentioned it
21
22
Just a wrap-up.
We do have
GWEN HOOTEN:
23
extra copies of the proposed plan.
If you wish to be a
24
part of our mailing list, we ask that you come down and
25
sign up with us.
We will be issuing in both The Denver
PAMELA MEADE COURT REPORTERS
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Post and the Rocky Mountain News the notification that
the comment period has been extended.
2
3
If there are no other questions we can
4
answer tonight, then we'll formally close this meeting.
Thank you to the teacher at Littleton.
5
6
Your students had excellent questions.
7
(The hearing was concluded at the hour of
8
9:30 p.m.)
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
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13.2 Response to
Written Comments on the
Proposed Plan for Operable Units 1 & 6
Shallow Ground-Water and Subsurface Liquids
and
Deep Ground-Water Operable Units
August 1993
13.2.1
EPA's Response to Comments from
Citizens Against Lowry Landfill
Richard Schelin, Chairman
Comment
None of the proposed alternatives meets the legal requirements in the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) because the
alternatives fail to treat any meaningful percentage of the 142 million gallons of
hazardous waste dwnped in Section 6 of the landfill. The alternatives are indefinite
containment strategies, TWt cleanup strategies.
Response
Section 121(a) of CERCLA mandates that EPA select appropriate remedial actions that
are in accordance with Section 121 and, to the extent practicable, the National
Contingency Plan (NCP), and which provide for cost-effective response. Each of the
remedial alternatives described in the Proposed Plan for Operable Units (OUs) 1 & 6
meets these legal requirements. Consistent with Section 300.430(a)(iii)(C) of the NCP,
in developing appropriate remedial alternatives for the Site, EP A considered a
combination of methods to achieve protection of human health and the environment.
EP A considered the expectation described in the NCP that in appropriate site situations,
treatment of the principal threats posed by a site (with priority placed on treating waste
that is liquid, highly toxic or highly mobile) will be combined with engineering controls
and institutional controls, as appropriate, for treatment residuals and untreated waste. In
addition, EPA also considered the expectation described in the NCP that engineering
controls, such as containment, will be used for waste that poses a relatively low long-
term threat or where treatment is impracticable. Containment was chosen at the Lowry
Site because of the low level offsite risks and because it is impracticable to remove the
waste. The NCP recognizes that containment should be used to remediate waste present
in low levels, waste that is technically infeasible to treat, and large volumes of waste.
Treatment of contaminated ground water is a principal component of EPA's selected
remedy for OUs 1 & 6. Treatment of ground water beyond that included in that remedy
would be impracticable, given the prohibitively high costs and adverse short-term effects
to onsite workers associated with such treatment.
DENIOOIS3A4.WPS
13-83
-------
The selected remedy for OUs 1 & 6 is expected to immediately treat 23,652,000 gallons
of water per year extracted from the Shallow Ground Water and Subsurface Liquids at
the Site. The selected remedy components for OUs 2 & 3 and 4 & 5 include, in part,
treatment to address Landfill Solids and Gas, Surface Water and Sediments at the Site.
Comment
EPA should establish a new-technologies escrow fund of $75 millionfor ultimate cleanup
of the Site. The interest-bearing escrow fund would be available on a competitive basis
to vendors of technologies that detoxify the hazardous waste in Section 6. Payments
would be based on the number of gallons of chemicals of concern (COC) that are
removed.
Potentially responsible parties (PRPs) would be required to place in escrow $75 million
in an interest bearing account. At each 5-year review interval, EPA would issue a
Request for Proposals for vendors to apply new technologies to treat the remaining
millions of gallons of hazardous waste at Section 6. Pursuant to a public process, EPA
would review the proposals to identify the proposal(s) that results in the greatest
treatment of hazardous waste at the lowest cost. Any qualifying proposal would have to
meet community protection standards and be subject to bonding to assure performance.
The winning vendor would be paid according to the number of gallons (or pounds) 01
hazardous waste treated. EPA's administrative costs would be strictly limited to
5 percent of the amountpaid the vendor. Funds not paid to the vendor would remain in
the escrow account to be available at the next review in 5 years. EP A would have to
assure all interested vendors access to the Site and preclude the Site owner/operator from
barring competition, as Waste Management has tried to do during the Remedial
Investigation/Feasibility Study (RI/FS).
Response
CALL's proposal raises a number of legal and policy concerns, including the fact that it
does not specify a remedy which can be evaluated against the NCP criteria for remedy
selection.
EPA has determined that the selected remedy for OUs 1 & 6 will be protective of human
health and the environment, and will use the 5-year review process under Section 121(c)
of CERCLA to ensure that the selected remedy remains so protective. If the Agency
determines during a 5-year review that the remedy is no longer protective, it may review
new technologies and evaluate whether they are appropriate for implementation at the
Site.
DENlOOlS3A4.WP5
13-84
-------
Comment
/fEPA abandons the cleanup objective at the Lowry Site, the agency will send a clear
signal to all PRPs that the most effective method of avoiding cleanup of a Supeifund site
is to make it inaccessible by burying it under tons of municipal solid waste.
Response
EPA has not abandoned the cleanup objective at the Lowry Site. The primary remedial
action objectives for OUs 1 and 6 are the following:
.
Prevent human exposure (through ingestion, inhalation, and dermal
absorption) to liquids containing contaminants in excess of the remediation
goal
.
Prevent migration of contaminants that would result in ground-water
concentrations in excess of the remediation goal
The selected remedy for OUs 1 & 6 meets these objectives. As discussed above, the
NCP recognizes that containment should be used to remediate waste present in low
levels, waste that is technically infeasible to treat, and large volumes of waste. In
addition, EP A guidance on Conducting Remedial Investigations/Feasibility Studies for
CERCLA Municipal LandfIll Sites recognizes that "[c]ontainment has been identified as
the most likely response action at these sites because (1) CERCLA municipal landfills are
primarily composed of municipal, and to a lesser extent hazardous wastes; therefore, they
often pose a low-level threat rather than a principal threat; and (2) the volume and
heterogeneity of waste within CERCLA municipal landfills will often make treatment
impractical. "
Comment
The alternatives give insufficient attention to the maximum extraction and treatment of
hazardous constituents at the landfill because approximately 96 percent of the hazardous
material in the waste pits will remain after 30 years of treatment.
Response
Although EPA does not agree with the specific analysis presented, the Agency does agree
that a large portion of wastes will remain in the waste pits. The FS evaluated waste pit
pumping and treatment and found that a significant reduction in volume cannot be
achieved because of residual contamination. Because removal of wastes from the waste
pits is technically infeasible and not cost-effective, EPA did not include waste pit
pumping as a component of the selected sitewide remedy. Excavation and disposal of the
contents of the shallow waste pits in the former tile pile area is, however, part of the
selected remedy for OUs 2 & 3.
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Comment
In the near term, EPA should assume full development of all lands up to the boundaries
of Sections 6 and 31. In the long term, EPA should assume full development of all lantis,
including Sections 6 and 31. The buffer zone ordinance adopted by the City of Aurora
was intended to protect citizens from the dangers from the landfill prior to and during
cleanup. In convoluted logic, the PRPs argUf!, however, that they should not have to
conduct extensive cleanup at the Site because EPA should assume institutional controls to
prevent use of Sections 6 and 31 and adjacent land and related ground water now and in
perpetuity .
CALL urges EPA to assume no institutional controls and ultimate full use of Sections 6
and 31 and order a cleanup accordingly.
Response
The risk assessment was based on ultimate residential use of both Sections 6 and 31.
However, the lack of technologies to detoxify the waste pits has lead EP A to consider
containment-based remedial alternatives with onsite institutional controls. EPA has
determined that the selected remedy for OUs I & 6 is the most appropriate and
technically feasible remedy to address Shallow Ground Water and Subsurface Liquids at
the Site. During the 5-year review, if EPA finds the remedy is not protective, EPA may
review new technologies and evaluate if they are appropriate for implementation at the
Site.
Offsite institutional controls will serve as an additional measure of protection to enhance
the effectiveness of the selected remedy and to act as preventative measures to preserve
the implementability and effectiveness of any of the selected remedy contingency
measures.
Comment
By limiting the remedial alternatives to containment strategies and not advancing options
involving significant cleanup, EPA is rewarding PRPs for systematically making cleanup
of a Supeifund site more expensive and difficult. It is unconscionable that PRPs woulil
now be able to claim cleaning up Section 6 is too costly after one such PRP consciously
and systematically piled years worth of trash on the Site after the Site was placed on the
National Priorities List (NPL). This type of chicanery for private profit at the expense of
the public interest cannot be tolerated. EPA's sanctioning of this behavior by PRPs will
send a signal to PRPs at other sites that it is profitable to make cleaning up their Super-
fund sites as costly as possible, because EP A will let them off the hook. By sanctioning
such behavior, EPA will emasculate the central feature of CERCLA, which is that the
polluter must pay.
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Response
EPA does not believe that it is rewarding PRPs, who will ultimately pay the costs of
cleanup, for piling trash on the Site over the years. The Lowry Site was permitted as a
landfill for municipal and industrial disposal prior to becoming a Superfund site. In
1984, when the Site was placed on the NPL, the Site already had a significant amount of
municipal waste as well as industrial waste. The Lowry Landfill was the prime recipient
of municipal waste from the Denver metropolitan area. Rather than close the landf1l1
without a viable alternative municipal landfill, a decision was made to continue landfilling
operations until another facility could be opened.
Comment
CAIL proposes that EP A adopt an innovative strategy for the long-term cleanup of the
Lowry Landfill, which will also send a signal to PRPs that they cannot escape cleanup
responsibilities. The strategy involves tWo elements:
1.
Adopt and implement modified Alternative 5, which will contain the hazar-
dous waste on Section 6, bUt only treat a small portion of the 142 million
gallons of hazardous waste in the ground.
2.
Place $75 million in an interest-bearing escrow account for applying new
technologies to treat the millions of gallons of hazardous waste remaining
at the Site after implementation of EPA 's preferred alternative.
To meet the requirements of CERCLA, waste at sites on the NPL is to be treated, not
merely contained. All the alternatives being considered by EPA now amount to contain-
ment strategies. None of the strategies treats a significant amount of the waste at the
Site. The PRPs and EPA are apparently convinced that current technologies are
insufficient to meet the treatment requirements of CERCLA.
Response
EPA acknowledges support of the preferred remedial alternative for ODs 1 & 6 as
expressed in the Proposed Plan. EPA disagrees with the statement that "[t]o meet the
requirements of CERCLA, waste at sites on the NPL is to be treated, not merely
contained." (See response to CALL's first and second comments.)
Comment
Under CERCLA, EPA is required to review cleanup sites no less often than every 5 years.
However, CALL is unaware of any circumstances where EPA has conducted the required
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review and taken additional cleanup action following that review. Failure to take addi-
tional actiQn may be for a number of reasons:
.
Few sites have reached the 5-year review period
No new cleanup technologies have become available prior to the review
It is too difficult to acquire money to institute new cleanup actions
Bureaucratic inertia, which seeks to close the door on sites that the agency
says it has cleaned up
.
.
.
CALL's proposal would overcome these problems while instilling competition in a cleanup
process characterized by a lack of competition. Competition will necessitate developing
an aggressive program that will implement new technology and, ultimately, lower costs.
The program will be applicable to the Lowry Landfill and similar sites.
Response
EP A agrees with the fIrst two bullets, but disagrees with the remaining items. PRPs are
liable for the costs of new cleanup actions. Furthermore, EPA does not "close the door"
on any site so long as any wastes remain there.
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13.2.2 EP A's Response to Comments
from City of Aurora
Comment
Remove the element of the Plan that suggests that Aurora will maintain indefinitely its
cu"ent restrictions on land and water development in the City around the Supeifund site.
The City Council enacted the ordinances as temporary protection at a time when it was
not known if contamination had migrated off the Site or if the potential for exposure
would be heightened during the Site investigation and stabilization.
Institutional controls should not be used as a substitute for cleanup actions, and site con-
taminants should be controlled so as to avoid ojfsite impacts.
Since the site stUdies have confirmed that contaminants are currently contained onsite and
that it is technically and economically feasible to prevent migration beyond the
compliance boundaries, we do not see the need for ojfsite institutional controls as a
component of the ground-water remedy.
Response
The Proposed Plan cites Aurora's ordinance as an example of an existing institutional
control. The risk assessment recognizes that existing institutional controls may be
withdrawn or repealed. The selected sitewide remedy is a containment-based remedy.
Therefore, permanent, enforceable, onsite institutional controls are required. Offsite
institutional controls will serve as an additional measure of protection to enhance the
effectiveness of the selected remedy and to act as preventative measures to preserve the
implementability and effectiveness of any of the selected remedy contingency measures.
Comment
Provide additional information on the efficacy and cost-effectiveness of the upgradient
system to control the flow of ground water into the Site. Would the system reverse the
ground-water gradient to the south?
Response
The upgradient system proposed to control the flow of ground water into the Site will
intercept clean ground water flowing from the south into the Site. The purpose of the
system is also to prevent contaminant migration to the south, so that a hydraulic gradient
reversal to the south will not occur.
The additional cost associated with the upgradient system is anticipated to be approxi-
mately $2 million. This cost will be offset by the benefits derived from the upgradient
system. The following benefits have been identified:
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.
Enhanced isolation of site contaminants.
.
Prevention of offsite contamination migration, which may occur through
the unidentified sand stringers/sand channels and other geologic
heterogeneities.
.
Mitigation of contaminant migration on the south that may result from
localized ground-water flow to the south, chemical diffusion, dispersion, or
possible unidentified, localized seasonal changes in ground-water flow
direction.
.
Prevention of most clean ground water from entering the contaminated site,
thus reducing the treatment cost.
Comment
The EP A should make a commitment to funher evaluate the pumpability of selected waste
pits. Specifically, would it be possible to pump any of the waste pits downgradient of the
toe drain or funher nonh where the pits are relatively close to the surface? Such actions
could contribute to overall reduction of toxicity at the Site and could reduce long-term
problems, panicularly as they relate to significant venical contaminant migration.
Aurora requests this additional assessment infunherance of Superfund's directive to
choose permanent reduction of volume, toxicity, or mobility of wastes wherever
practicable.
Response
EPA evaluated this option in the FS. EPA also evaluated the option of excavating and
removing the shallow pits downgradient of the toe drain. Excavation and disposal of the
contents of shallow waste pits in the former tire pile area is part of the selected remedy
for OUs 2 & 3.
Comment
The following policy guidelines were adopted by Aurora City Coun.cil May 18, 1992, to
guide EPA and the panies conductin.g the site investigation in their development of the
following potential remedies:
Development Rights
1.
The site remedy shall not preclude either private development or the exercise of
water use rights around the Lowry Superfund site.
2.
The Record of Decision (ROD) shall not allow for migration of hazardous wastes
beyond the Superfund site boundaries as defined during the remedial investigation.
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Land Use Planning Around the Landfill
1.
Remediation options shall not presume that local government institutional controls
(e.g., the City of Aurora's i-mile perimeter development restriction) will be used
in lieu of cleanup actions.
2.
Cleanup strategies identified by EPA should conform to duly adopted and
approved local land use plans and programs of the City of Aurora and Arapahoe
County.
Cleanup Implementation
1.
The site remedy shall meet the CERCLA criteria of reducing contaminant toxicity,
mobility, and volume through treatment,' providing effectiveness over the long
term; and permanence.
2.
Reaching an ROD within the shortest reasonable time should be the priority of all
parties with an interest in the Site. Considerations regarding the apportionment of
liability must not be allowed to interfere with the process of identifying the site
remedy. EPA should take whatever action is necessary to implement the selected
remedy once the ROD is issued.
Funding
1.
Funds collected through the de minimis settlement process should be immediately
and solely dedicated to Lowry Superfund site cleanup actions. Cleanup actions
are those that involve treatment of the contaminants. They specifically exclude
transaction and administrative costs, including EPA oversight activities.
2.
Additional technical resources beyond the Technical Assistance Grant awarded to
Citizens Against Lowry Landfill should be made available to assist the community
in understanding and reviewing the cleanup alternatives being proposed for the
Site.
The above guidelines will be used by the Aurora Task Force as community standards
against which to evaluate proposed EPA cleanup alternatives.
Response
EPA acknowledges the policy guidelines adopted by Aurora City Council on May 18,
1992. EPA believes that the selected remedy for OUs 1 & 6 will meet the guidelines
described under Development Rights, Land Use Planning Around the Landf1ll, and Item 1
under the Cleanup Implementation criteria. With respect to Item 2 under Cleanup
Implementation, EP A believes that selecting a remedy within the shortest reasonable time
is a priority and will ensure that the selected remedy is implemented as soon as possible
after the ROD is issued. With respect to Item 1 under funding, the funds collected
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through the De Minimis settlement have been dedicated to the Fund to reimburse EPA's
past costs. ,
A Technical Assistance Grant (TAG), once issued, can be increased to a cap of $100,000
upon petition to EPA. In accordance with CERCLA Section 117(e), only one TAG is
issued per site. There are no other existing funding mechanisms for this type of assis-
tance. However, the current community relations program provides for two-way com-
munication between EPA and the members of the community. EPA has imparted to the
community considerable information regarding the Superfund process and the Site. To
date, EP A has committed funds, personnel, and other resources to assist the community
in understanding the cleanup alternatives for the Site.
Comment
We wish to point out two inaccuracies in the FS report and Proposed Plan with respect to
Aurora's ordinances and land use planning efforts.
The first relates to references in both documents that Aurora's ordinances 87-165 and
87-166 currently prohibit development of structUres within 1 mile of the Site and well
development within 1/2 mile of the Site. This is not true. Aurora's code does not
prohibit development within the referenced area because the property within a mile 01 the
Superfund site is not within Aurora's municipal boundaries. Property within a I-mile
radius of Section 6 is in unincorporated Arapahoe County, which does not expressly
prohibit development in the vicinity.
EPA is aware that the Aurora City Council enacted its two ordinances restricting develop-
ment with City limits around the Superfund site because of technical uncertainty aboUt the
potential for ojfsite health risks. The Council stated that they would reevaluate the
restrictions at such time as significant new data became available. With the near
completion of the site investigation and baseline risk assessment, the City Council has
begun to evaluate the continuing need for the ordinances. The Council will assess
whether the technical data support reducing or removing the restrictions.
The second inaccuracy is on page 7-5 of the Final Draft Feasibility Study, which states in
a discussion of the Southeast Area Planning Initiative that the joint planning task force
has recommended that a nonresidential or open space buffer of at least 1/2 mile remain
around the landfill. While the concept of buffers around the Superfund site has been dis-
cussed by the taskforce, no specific recommendation has been made by the group, which
is strictly advisory to the Aurora City Council and Arapahoe County Board of County
Commissioners.
The Lowry Landfill Environs element of the Southeast Area Planning Initiative was under-
taken by Arapahoe County and Aurora, with participation by the City and County 01
Denver, to provide EP A a conceptual land use plan for the Superfund site and
immediately surrounding area to facilitate the evaluation of site remedies. As an invited
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participant in the planning effort, EPA will receive prompt notice of any land use
decision.s that are made by the jurisdiction.s.
Response
EPA appreciates the information provided. As described in the ROD, offsite institutional
controls will serve as an additional measure of protection to enhance the effectiveness of
the selected remedy and to act as preventative measures to preserve the implementability
and effectiveness of any of the selected remedy contingency measures.
Comment
We believe it is critical that the selected remedy rely first on physical barriers to contain
the site wastes, and that the performance of these physical containment systems be
evaluated by a comprehen.sive and carefully designed monitoring program.
Because of the potential for contaminants to migrate to the east and west of the source
area, the proposed physical barrier systems along these boundaries should both be
installed immediately. The City particularly urges EPA to resist any efforts to delay the
installation of the western boundary system, since development activity to the west of the
site has been steadily increasing.
Response
The selected remedy for OUs I & 6 includes lateral containment on the eastern and
western portions of the Site. EP A considers containment to be the key concept that may
be implemented by several specific technologies. EP A has determined that physical
barriers (such as installing a barrier wall) are more protective of human health and the
environment because of the existence of sand lenses at the Site.
Comment
To the extent possible, contaminants should be kept from spreading beyond the
compliance boundaries, even if the concentrations of those contaminants would meet
cu"ent Applicable or Relevant and Appropriate Requirements (ARARs). EPA may avoid
the need for upgrading the cleanup plan in the future by con.servatively setting
remediation goals and remedial action objectives close to background levels now.
Response
The threshold criteria for selection of a remedy is protection of human health and the
environment and attainment of ARARs. The NCP states that the acceptable site risk
range for human health is 10-4 to lO-6 for Superfund sites. EPA does not agree that
cleanup should be to background levels for this Site. Based on the nine criteria and the
risk range specified in the NCP, EP A cannot justify cleaning up to background levels for
all contaminants at Lowry.
DENlOO153A4. WP5
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Comment
Long-term maintenance of the suiface water removal action, the landfill cap, and the
existing monitoring system is essential to a successful remedy. Also, since the majority 01
the ground-water contaminants will probably remain untreated in Section 6 indefinitely,
the institutional controls outlined in Denver's Executive Order 97 will need to be enforced
to prevent potential exposure on the Site.
Response
EP A agrees with this comment. As to Executive Order 97, EP A agrees that it will need
to be enforced and that additional restrictions on the use of the Site will need to be
implemented.
Comment
An effective containment and collection system, as described in Alternative 5, will be used
to control further horizontal migration of contaminants in the shallow ground-water
system. However, we strongly concur with EPA that, in addition, an effective long-term
monitoring system must be developed to confirm aquifer characteristics and ground-water
migration over time. References in the FS to uncharacterized heterogeneities, such as
high permeability sands or fractUres and uncertainties in site data, underscore the
importance of an adequate monitoring system, particularly to assess vertical migration.
We understand that the conceptual model will be used only for planning and not for
management purposes, and we fully support this decision.
Response
EP A agrees with this comment.
Comment
If the conceptual site model is accurate, contaminant migration to the compliance boun-
daries is not expected to occur until after the 3D-year estimated life of the cleanup reme-
dies. At that time, there will likely be far more development around the Superfund site
than there is today. This raises concerns for Aurora, despite EPA and PRP assurances
that because of Superfund-mandated 5-year reviews, remedial activities at the Site will
continue as long as they are necessary. It is critical that EPA accurately estimates
cleanup costs and contingencies and is diligent in efforts to legally secure these resources
at the time the remedy is negotiated. Any number of circumstances at the Site could
significantly increase futUre risks. Unforeseen operation and maintenance problems, for
example, could compromise the effectiveness of the remedy if there is a funding shortfall
at the critical period.
Significant funds have already been paid to both EPA and Waste Management through the
settlement process at the Site. A small portion of these funds dedicated now could grow
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to a substantial resource to finance future contingencies. The City requests that EPA
investigate this and other potential options for ensuring that we are not faced with a
shortage of funds to properly manage the Site at a time in the fillure when it may be most
needed.
Response
EP A agrees that ground-water containment and treatment will continue in perpetuity since
wastes will remain on the Site. EP A will seek to obtain financial assurance from any
PRPs performing the remedy to ensure continued O&M of the remedy.
Section 107 of CERCLA provides EP A with the mechanism to obtain cleanup funding in
the event that the PRP performing the RD/RA is no longer viable.
Comment
South Barrier System - We have some questions regarding the relative benefit of the pro-
posed barrier and/or diversion system upgradient of the Site along the southern
compliance boundary. Is there any potential for the barrier to cause a reversal of the
ground-water gradient to the south? Could the existence of the barrier impede potentially
beneficial downgradient flushing of the contaminants? Before endorsing installation of an
upgradient barrier, the City requests that EPA provide additional information on the
effectiveness of the concept. We raise this question particularly in light of the conclusion
that migraticn of ground water onto the Site from the south is responsible for only a very
small portion of the total annual infiltration.
Response
The relative benefits of the upgradient system were discussed previously (see response to
City of Aurora's second comment). Migration of ground water onto the Site from the
south is responsible for only a small portion of the total annual infiltration and would not
result in beneficial flushing. However, intercepting this flow is one of the secondary
benefits of the upgradient system. The primary benefit is isolating and preventing site
contaminant migration to the south, as discussed earlier.
The Activity Report for Oversight of Compliance Boundary Sampling, dated May 1993,
shows exceedances of the Preliminary Remediation Goals (pRGs) to the south or the
upgradient portion of the Site. In addition, the Ground-Water Use Evaluation (Lowry
Coalition, Draft Addenda 2 and 3 to the Ground-Water Well Inventory Technical
Memorandum, dated July 24 and October 25, 1991, describes the effects of an operating
municipal or industrial well in Section 7. The modeling results show that a reversal in
the gradient flow will be induced by pumping. The function of the barrier wall will be to
prevent contaminants from flowing with the reversed gradient and migrating offsite.
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13.2.3 EP A's Response to Comments
from Colorado Department of Health
Comment
The proposed point of compliance does not meet certain ARARs and to be considered
(TBC) values. The state would be willing to consider a waiver of the Resource Conserva-
tion and Recovery Act (RCRA) ARAR if sufficient justification exists, and pursuant to the
basic standards for ground-water requirements, if two points of compliance are
established. The first boundary would be called a Point of Action (POA) and would be
set at the current extent of contamination. The second boundary would be called a Point
of Compliance and would be set at the property boundary as shown in the Proposed Plan.
The purpose of the POA boundary would be to trigger corrective measures to address
migrating contamination beyond the areal extent of the existing plume. This will allow
for additional time to correct a problem before offsite migration. The POA need only be
set as a concept at this time, with the actual identification of the POA boundary to be
made when sampling takes place during remedial design of the selected remedy.
Response
EP A has included POA and compliance boundaries in the ROD for the Site. Monitoring
at the POA allows contamination to be addressed (via the planning and implementation of
appropriate response actions) before it reaches the compliance boundary, thus preventing
exceedances of performance standards at the compliance boundary.
Consistent with the NCP, the compliance boundary has been established at the edge of
the waste management area because the waste has been left in place. In this context, the
waste management area encompasses the following waste management units: waste pits,
sewage sludge application areas; leachate injection areas; command post; subsurface
barrier wall and treatment facility; and leachate sprayback areas. In establishing the
compliance boundary, EP A considered the proximity of the sources, the technical
practicability of ground-water remediation, the vulnerability of the ground water and its
possible uses, and the likelihood of exposure. Under this approach, there will be no need
to waive the ARARs because ARARs will be met.
The actual surveyed location of the POA and compliance boundaries will be determined
by EP A during RD.
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13.2.4
Comment
EP A's Response to Comments from
East Cherry Creek Valley Water
and Sanitation District
The East Cherry Creek Valley Water and Sanitation District (the District) was established
in 1962, before Denver's acquisition of Section 6 from the Army. The District presently
serves over 5,000 accounts including homes, schools, churches, and commercial
properties. Presently comprising a population of over 15,000, the District is poised to
grow within its service area to serve as many as 90,000 people. Ground water in the
Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers is the primary source of
water for the District and will continue to be a vital component of the District's water
supply as it develops. Through its irrigation returnjlow recapture programs, the District
is also using water from the shallow alluvial aquifer systems within its boundaries.
Considering its reliance on ground-water resources, the District cannot tolerate any
migration of hazardous waste off of the Lowry Landfill me. We have reviewed EPA's
recommended alternative for remediation of the ground-water OUs on the basis of this
standard.
The District believes very strongly that an immediate and active approach to cleaning up
and containing the wastes is crucial to the protection of its water supplies. It further
believes that the remediation program should include, at a minimum, the construction of
the perimeter barriers and collection facilities as depicted in the recommended
alternative. Although it generally supports the concepts outlined in the recommended
alternative, the District remains concerned with the effectiveness of the cleanup and the
impact it may have. Specifically, the District has the following general concerns:
DENlOOI53A4.WP5
1.
It is opposed to using any ojfsite institutional controls which will in any
way reduce, or restrict our access to ground water within the service area
of the District.
2.
It believes that it is critically important that the monitoring program devel-
oped be designed and operated in a fashion that will allow for the effective
identification of any vertical migration of the plume, or migration of the
contamination off of the Site.
3.
There is currently no quantification of the impact the dewatering and
cleanup would have on the District's water supplies. The District requests
that such an analysis be undertaken, and that a means for replacing water
impacted by the cleanup be developed.
4.
It is concerned that the cleanup, as presented, may allow contamination to
move beyond the western site boundary and onto the District. It under-
stands the well system will be in place to help mitigate offsite contamina-
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tion. However, if these wells are not operated until PRG (Preliminary
Remediation Goals) levels of contamination arrive at the boundary, consid-
erable contamination may migrate onto the District. It strongly
recommends that the "trigger" level for starting the operation of the west-
side containment well system be set at some agreed upon background level
rather than the PRGs. The water it currently delivers to customers is weU
within mandatory Safe Drinking Water Act (SDWA) standards, and it does
not want a portion of its water supply to deteriorate to a marginal level of
acceptance.
5.
It requests that some additional effort be made to reduce toxicity onsite
through the pumping of selected waste pits.
Our detailed comments are incorporated in the following document. Please include this
cover letter into the formal record with, and as part of, our comments.
Response
EPA notes that the cover letter is included as part of the District's comments. All have
been placed into the Administrative Record for the Site. EPA has responded to the five
general concerns in the District's detailed comments below. The selected remedy for
ODs 1 & 6 is, in part, a containment remedy that will halt offsite migration of
contamination.
Comment
Institutional Controls-The District is strongly opposed to incorporating arry offsite
institutional controls that would in any way restrict its access to, or use of water within
its boundaries.
The District does not have surplus water to attribute to a "buffer zone." All water within
its boundaries is committed in the District's water supply planning to meet .future
demands. It cannot donate water to the cleanup effort either to provide an additional
margin of safety in the event that the ground-water modeling is inaccurate, or to facilitate
the operation of the ground-water collection system. The proposal does not include any
detailed analysis of what impact ojfsite institutional controls would have on District
adjudicated water rights and/or nondecreed water within its boundaries.
Response
As described in the ROD, offsite institutional controls shall serve as an additional
measure of protection to enhance the effectiveness of the selected remedy and to act as
preventative measures to preserve the implementability and effectiveness of any of the
selected remedy contingency measures. Offsite institutional controls shall include, but
not be limited to, deed notices and restrictions, zoning controls, and well restrictions.
These controls must prohibit all offsite activities in the vicinity of the Lowry Site that
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would interfere or be incompatible with, or that would in any way reduce or impair the
effectiveness or protectiveness of, the selected sitewide remedy.
Comment
Ground- Water Modeling - What is the potential for future impacts to the deep aquifers
beneath and adjacent to the Site if this plan is implemented? At the Aurora Ordinance
Review Meeting on February 21, 1993, representatives of the City of Denver concluded
that the deep aquifers, including the Arapahoe Aquifer, may not be protected and may
become contaminated if nearby wells are allowed to pump. This is fully contrary to our
understanding of the conclusions reached by EPA and the Coalition. We request that the
modeling be reviewed and rerun, if appropriate, to resolve these questions.
Response
To address concerns that dissolved contaminants may migrate vertically downward under
pumping conditions, EP A completed several scenario runs for potential receptors in the
Denver and Arapahoe Formations using the FS model. The purpose of the simulations
was to evaluate the impact of pumping near the Site on the Denver and Arapahoe
aquifers. The simulations considered municipal wells pumping in a dewatered aquifer
that reached water table conditions because of an assumed high level of ground-water
development. These are conservative conditions because the existing confining conditions
within the Denver and Arapahoe aquifers help reduce the rate of downward migration.
Under water table conditions, the hydraulic head in the aquifer is lower than the head
under confined conditions, resulting in an increase in the downward hydraulic gradient,
which promotes downward vertical contaminant migration. This scenario simulates
greater pumping than the total consumptive use currently allowed by the Denver Basin
Rules. The results of the simulations indicated that no detectable dissolved contamination
was predicted to reach the Denver or the Arapahoe Formations within the 200-year
simulation period. It should be noted that to date, EP A has no reliable mechanism to
predict migration of dense nonaqueous phase liquids. However, EPA will implement a
vertical migration contingency plan to monitor and remediate, if necessary, migration of
dense nonaqueous phase liquids.
Comment
Ground-Water Monitoring- What are the primary components of the monitoring system
and how will they be designed? Since the modeling suggests that there will be little
vertical migration of contaminants, engineered facilities to control vertical flow were
abandoned in favor of monitoring of the deep ground-water system. This places a great
deal of importance on the placement and design of the monitOring facilities. It is
particularly important to the District that deep aquifer monitoring facilities be effective,
and yet constructed in a manner to assure that the wells themselves will not, in the future
provide a preferential pathway for contaminant migration vertically downward.
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Response
The design and placement of the monitoring well network will occur during RD.
However, EPA understands the District's concern that the monitoring wells should not
provide a conduit for vertical migration. Monitoring wells that must be drilled through
waste disposal areas will be installed with appropriate precautions. EP A would welcome
any additional information and/or comments from the District pertaining to well
monitoring and design.
Comment
Is there a vertical compliance boundary? Clearly, if cOnlamination was identified offsite
in excess of ARAR standards, some sort of remedial activity would be dictated. However,
it is not clear what actions would be taken if monitoring confirmed that the plumes were
migrating vertically downward inlO clean ground-water systems within the area of the
compliance boundary.
Response
The top of the lignite layer is selected as a vertical compliance boundary and response
action will be taken if contaminants migrate to this layer. The response action to be
taken will be determined by the magnitude and speed of the migration event, the
contaminants involved, contaminant concentration, and other physical parameters.
Comment
Who will be responsible for the Site in the long term (30+ years); and specifically, where
is this responsibility described?
Response
Pursuant to Section 107 of CERCLA, the PRPs remain liable for all response costs
associated with the Site, regardless of when incurred. Response costs were estimated for
the 3D-year present worth to provide a basis for comparing remedial alternatives. The
3D-year period was not intended to signify the length of the remedial action. Under the
selected remedy for OUs 1 & 6, the collection and treatment of contaminated ground
water will continue in perpetuity. EPA, through the 5-year review process, will assure
that human health and the environment are being protected by the remedial action
selected for the Site.
Comment
What impact will the perimeter collection systems have on water availability and water
rights, and how will these impacts be mitigated? We have seen no analysis of how the
proposed dewatering systems might impact water beneath adjacenl parcels within the Dis-
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trict, and how replacement water might be made available to the District to compensate
for any adverse impacts.
Response
The impact that the cleanup would have on the District's water rights is negligible for the
following reasons:
.
The remedial activities include extraction of contaminated ground water at
the Site, ground-water treatment, and reinjection of the treated ground
water at the Site; therefore, what is extracted from the ground water will
be returned. This results in a net balance of zero; therefore, the amount of
available ground water has not changed.
.
The cleanup effort will target the Dawson Formation, which is not a major
water producer in the area.
Comment
Ground- Water Quality - It is not clear exactly where the compliance boundary is currently
proposed to lie. We would like better definition of this boundary.
Response
The proposed compliance boundary as shown in Figure 3 of the Proposed Plan is a
conceptual boundary. Conceptually, the boundary consists of a southern boundary at East
Quincy A venue; a western boundary at Gun Club Road; an eastern boundary at the
current fence running north/south in Section 6; and a northern boundary that is an
extension of East Hampden Avenue with the exception of protrusions into Section 31 to
encompass the barrier wall and command post. The actual surveyed location of the
compliance boundary will be determined by EPA during RD.
Comment
Will the concentration of contaminants within plumes inside the compliance boundary be
allowed to increase from current levels as long as compliance is attained at the
boundaries?
Response
The concentration of contaminants could theoretically increase inside the compliance
boundary. However, performance standards, including ARARs, must be met at and
beyond the compliance boundary. Monitoring will be required within the plume of
contaminated water, but action will not be taken unless contamination above the standards
described in Section 11 of this ROD crosses the PDA boundary.
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Comment
Will contaminants be allowed to spread beyond the compliance boundary as long as
ARARs and PRGs are met? For example, if the PRG for lead is set at 50 micrograms per
liter (Table 2.1 in the FS), and the natural background lead is less than 5 micrograms
per liter, will lead contamination be allowed to spread beyond the compliance boundary
as long as it does not exceed 50 micrograms per liter? Although this is a concern with
regard to all parameters, lead is a particularly good example. While the maximum
contaminant level (MCL) for lead remains at 50 parts per billion (Ppb), the new EPA
notification and treatment level for lead in drinking water lies at only 15 ppb. We
recommend bringing the PRG for lead into conformance with the new EPA lead-copper
rule.
Response
The threshold criteria for selection of a remedy is protection of human health and the
environment and attainment of ARARs. The NCP states that the acceptable risk range
for human health is 10-4 to 10-6 for Superfund sites. Based on the nine criteria and the
risk range specified in the NCP, EP A cannot justify cleaning up to background levels for
all contaminants at Lowry.
Performance standards listed in the ROD, including ARARs and TBC values, use the
most current information available at the time the ROD is issued.
Comment
Will there be provisions for alteration of the PRGs in the future as SDWA regulations
become more comprehensive and stringent?
Response
CERCLA mandates EP A review of the remedy no less often than every 5 years as long
as any wastes remain at the Site, allowing the remedy to be modified if it is not
protective of human health and the environment.
Comment
Will any ojfsite ground-water degradation be allowed to occur before pumping from the
barrier system is initiated? The EPA monitoring, as well as the District's own
monitoring, indicate that the ground water underlying the District has not yet been
impacted by the Lowry facility. The District's wells produce water containing some
natural mineralization, but no organic or other induced contaminants. The District feels
very strongly that the contaminant plume should be contained on Section 6, and should
not be allowed to migrate off the Site onto the District at any levels. The District feels
this is particularly important since the recommended alternative is not an effective
cleanup proposal, but is in truth a containment program. The District recommends that a
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"trigger" level for starting the operation of the containment well system on the west
boundary be set at some agreed upon background level rather than the PRGs. The water
the District currently delivers to customers is well within mandatory SDWA standards,
and the District does not want a portion of its water supply to deteriorate to a marginal
level of acceptance.
Response
Offsite migration of contaminated ground water, as measured by the performance
standards, including ARARs, will not be allowed to occur beyond the compliance
boundary. Monitoring at the POA will allow quick response action to ensure that
contaminants above performance standards, including ARARs, are not allowed to migrate
beyond the compliance boundary.
Based on the nine criteria and the risk range specified in the NCP, EP A cannot justify
cleaning up to background levels for all contaminants at Lowry.
Comment
Removal of Waste-Can any of the pits be effectively pumped to help reduce the volume
of waste on the Site? The recommended alternative removes only relatively small
amounts of waste from the Site. Instead, it relies upon containing the Site throughout the
foreseeable future. If it appears that the pits as a whole cannot be effectively pumped,
the District would like to know if there are select pits that could be pumped efficiently to
help reduce the overall toxicity of the Site and diminish the long-term threat to the ground
water.
Response
EPA evaluated the effectiveness of waste pit pumping and found that only a small portion
of wastes can be removed through pumping. Residual contamination of liquids that are
sorbed onto various waste materials will provide a continuous source of ground-water
contamination. Excavation and disposal of the contents of shallow waste pits in the
former tire pile area is part of the selected remedy for ODs 2 & 3.
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13.2.5 EPA's Response to Comments
from William G. Kennedy
Comment
Page 8, Table 1 of the Proposed Planfor OUs 1 & 6, last column-shows costs of Alter-
native 5 to be $59 million and Modified Alternative 5 to be $61 million. Page 6 shows
costs of Alternative 5 and Modified Alternative 5 to be $17,680,000 and $21,100,000
respectively. What is the reason for this discrepancy?
Response
The $17,680,000 for Alternative 5 and $21,100,000 for Modified Alternative 5 represent
the funds needed to design and construct the components of the project in a period of
3 years. These costs are referred to as the capital costs. In addition to the capital costs,
EPA has estimated the cost to operate and maintain the project, typically referred to as
O&M costs. The present worth is the amount of money you would need to have today,
assuming that this money would collect 5 percent interest per year, to construct and
operate the remedy for 30 years. The $59 million for Alternative 5 and $61 million for
Modified Alternative represent the 3D-year present worth values for both capital and
O&M costs.
Comment
Present worth cost figures are estimaled for all alternatives, but no mention is made of
the interest rate used to amortize present worth over 30 years. There is no indication
that the cost figures are estimates.
Response
EP A assumed a 5-percent discount rate. The FS report provides detailed information on
cost estimates. EP A agrees that the costs are estimates. The accuracy of the estimate is
subject to substantial variation since very little detail is known about the specific design
of each alternative. Typically, the cost estimates are expected to be no more accurate
than -30 percent to +50 percent.
Comment
Figures 1, 2, and 3 indicate a "current landfilling area" in Section 36 to the north, just
outside the compliance boundary of the Proposed Plan. Is this an imminent future Super-
fund site?
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Response
No. Superfund was established to provide funding and enforcement authority for past
hazardous waste activities. The current landfill area in Section 31 deals with solid, not
hazardous waste and is permitted under Colorado Hazardous Waste Management
Regulations (CHWMR), which is a "cradle-to-grave" regulatory program for active
landfilling facilities.
Comment
The Proposed Plan mentions OUs 2, 3, 4, and 5, but does not delineate their location on
Figures 1, 3, or 4. Perhaps the above-mentioned "current landfill area" is actually
OU 2, 3, 4, or 5. Could the Proposed Plan be edited to clarify this confusion?
Response
Operable Units (OUs) 2, 3, 4, and 5 refer to media addressed at the Lowry Landfill
Superfund Site located in Section 6. The OUs refer to the following media:
.
Landfill Solids, OU 2
Landfill Gas, OU 3
Soils, OU 4
Surface Water and Sediments, OU 5
.
.
.
Their location is shown in the attached figures. The current landfill area is located in
Section 31, immediately north of Section 6.
Comment
The word "Permanence" in conjunction with Long-Term Effectiveness appearing at the
top of page 8 is defined on page 9 as "...the ability of a remedy to provide reliable
protection of human health and environment over time." The phrase "over time" is
meaningless. Could the word "permanence" appearing in the Proposed Plan be
quantified in number of years?
Response
The phrase "over time" was used because EPA is required to determine the magnitude of
residual risk remaining at the Lowry Landfill site after the remedy is implemented and to
determine the adequacy and reliability of the remedial measures and on site institutional
controls to manage remaining wastes. In this way, the long-term effectiveness and
permanence of the selected remedy can be demonstrated over time.
The word "permanence" cannot be quantified in years because the selected remedy is a
containment type of remedy. Since wastes will remain on the Site, containment and
treatment will continue in perpetuity.
DENlOO153A4.WP5
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Comment
Page 10, Short-Term Effectiveness. The text that follows this heading addresses risk to
construction workers, 3-year construction period, and special health protective measures.
This text has no bearing on the word "Effectiveness" and vice versa. This is a
nonsequitur. If Short-Term Effectiveness were changed to "Short-Term Adverse Effects, "
readers would be less confused. Could either the heading or the text be changed to make
sense (in English)?
Response
The NCP defines short-term effectiveness as the short-term impacts of the alternatives.
EPA agrees that the short-term effectiveness is measured by the magnitude of the short-
term adverse effects of implementing a remedy.
Comment
Short- Term Adverse Effects that may be unavoidable during construction in.clude
increased dust, noise, traffic, and perturban.ce of toxic leachate. Does EPA intend to
address these adverse effects to human health and environment in the final Proposed
Plan?
Response
Dust, noise, and traffic will be addressed in the final design of the remedy. Other short-
term adverse effects will be covered by the Occupational Safety and Health Act, which
addresses hazardous exposures in the work place, and the Emergency Planning and
Community Right-to-Know Act, which addresses unanticipated environmental releases.
Comment
Page 9, Implementability. The Proposed Plan does not acknowledge the differential
dumping by the PRPs, that large companies were the major contributors, and that
lawsuits are likely to be the greatest obstruction to implementability.
Response
The items listed in the comment relate to cost recovery. Selection of the remedy and cost
recovery are two distinct phases of the Superfund process. In general, EP A addresses
cost recovery issues after the remedy is selected.
Comment
Please regard these comments as honest inquiry and not as criticism. Everyone at EPA
that I talked to on the telephone, relative to Lowry or any other environmental concerns,
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have been outstandingly courteous, helpful, and prompt. Despite comments herein,
please count me as one in favor of the Proposed Plan as written.
Response
EP A acknowledges support of the selected remedy for au s 1 & 6 as expressed in the
Proposed Plan.
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13.2.6 EP A's Response to Comments
from the Lowry Coalition
Comment
The Lowry Coalition agrees that Alternative 5, as modified, meets the criteria that EPA
must consider in evaluating remedial actions at CERCLA sites, and, in particular, meets
ARARs and achieves overall protection of human health and the environment. The Lowry
Coalition supports EPA's Proposed Plan.
Response
EPA acknowledges support of the preferred remedial alternative for OUs I & 6 as
expressed in the Proposed Plan.
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13.2.7 EPA's Response to Comments
from Robert Velton, Pemex, Inc.
Comment
My proposal for a Proposed Plan modification and/or Revision of Closure Plan for the
Sussquehanna Hazardous Waste Site in Pueblo, Colorado, should be reviewed because it
has some different approaches, some technical data, and some private sector thinking that
may interest you at the Lowry site.
Response
The alternative methodology proposed for the Sussquehanna site is recycling. Based on
Table 1 of your proposal, you have concluded that no reasonable alternative to contain-
ment exists for the Lowry Landfill site. Containment is part of the selected remedy for
OUs 1 & 6. Your entire proposal is being retained as part of the Administrative Record
for those au s.
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13.2.8
EP A's Response to Comments from
United States Department of
Interior, Fish and Wildlife Service
Comment
The u.s. Fish and Wildlife Service (USFWS) wishes to convey its concern for potential
adverse impacts to natural resources by encouraging EPA to conduct an ecological risk
assessment for GUs 1 & 6 if one has not already been completed. Decisions for interim
actions and final remedy should be based on valid ecological risk assessments. We also
encourage EPA to consider the Endangered Species Act, Fish and Wildlife Coordination
Act, Migratory Bird Treaty Act, and the Bald Eagle Protection Act in planning for interim
actions and final remedies.
Response
EP A prepared an ecological risk assessment as part of the Baseline Risk Assessment for
Lowry ODs 2 & 3 and 4 & 5. Other ecological evaluations appear in the Preliminary
Endangerment AssessmenJ and the Remedial Investigation Report for the Shallow Ground-
Water and Subsurface Liquids and Deep Ground-Water Operable Units. The Lowry
Coalition conducted an Evaluation of Potentially Protected Resources for the Lowry
Landfill site and adjacent areas. This evaluation included an evaluation of threatened and
endangered species. The Lowry Coalition also conducted an investigation of the
distribution of wetlands in the area. This evaluation includes a description and mapping
of wetlands and a qualitative delineation of specific wetlands vegetation.
A list of the potentially endangered and threatened species thought to occur in the area of
the Lowry Landfill site is included in the Baseline Risk Assessment for ODs 2 & 3 and 4
& 5. Among the species listed, there are several species of raptor and terrestrial carni-
vore that may be subject to bioaccumulation processes. These species include the
Peregrine Falcon, the Bald Eagle, and the Swift Fox. While none of these species have
been observed at the Lowry Landfill Site, the USFWS considers the area a possible
habitat for these organisms.
The Lowry Coalition identified several endangered species that may be present in the
vicinity of the Lowry Landfill site, including the Bald Eagle, Peregrine Falcon, Whoop-
ing Crane, and Black-footed Ferret. Threatened species that may be present include the
Ferruginous Hawk, Mountain Plover, Long-billed Curlew, Preble's Jumping Mouse,
Swift Fox, Colorado Butterfly Plant, and Diluvium Lady's Tresses.
EP A will use information from the ecological risk assessments in making decisions for
the final remedy for the Lowry Landfill site.
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13.2.9
EP A's Response to Comments
from Waste Management of
Colorado, Inc., Chemical
Waste Management, Inc., and
the City and County of Denver
Comment
In geMral, Waste Management of Colorado, Inc., Chemical Waste Management, Inc.,
and the City and County of Denver (WMC/CWM/Denver) agree with the remedial
alternative that EPA has selected for the shallow and deep ground-water and subsurface
liquids OUs. The concept of containing and treating ground-water contamination at
Lowry is supported by WMC/CWM/Denver based upon:
1.
The significant short-term health risk that would be posed by removing all
contaminated materials at the Site, its technical impracticability, and cost/
beMfit;
2.
The proven inability at the Site to remove all of the contaminated liquids
from the landfill mass and underlying and surrounding subsurface by pump-
ing and treating du~ to low permeability; and
3.
EPA's Baseline Risk Assessment, which showed that ground water at Lowry
poses no current health risk, and only future risk if a number of very
conservative assumptions are made about the hydrogeology of the area,
and future land and water use.
Response
EPA acknowledges support of the preferred remedial alternative for OUs I & 6 as
expressed in the Proposed Plan.
Comment
In describing the practice of co-disposal, EPA states on page 3 of the Proposed Plan that
"it was thought that the municipal refuse would act as an absorbent for the liquid
wastes." While not 100 percent effective, municipal refuse did, in fact, absorb or retain
much of the industrial liquid disposed of at the Site. This is evidenced by the presence of
"perched" waste pits in the western portion of the Site, the presence of 95 million gallons
of contaminated liquids still within waste pits, 14 million gallons of contaminated liquids
in saturated refuse, and the proven increase in contaminant levels within the unsaturated
refuse within the ZOM formerly containing waste pits.
DENlOO153A4. WP5
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Response
EP A discussed the procedure of co-disposal in the Proposed Plan to describe what was an
accepted disposal practice in the past. This practice is no longer acceptable. EP A agrees
that the refuse acts as an absorbent for the liquid industrial waste, but notes that refuse
does nothing to address contamination from that waste. Unfortunately, a large volume of
waste pit liquids migrated beyond the boundary of the pits and as a result, has
contaminated every media at the Site.
In addition, it is also the presence of the refuse that makes liquid recovery difficult, if not
impossible, and not cost-effective. EPA disagrees that waste pits in the western portion
of the Site are "perched." The Lowry Coalition for OUs 1 & 6, dated March 1992,
concluded that the waste pits are in direct hydraulic connection with ground water. EPA
agrees with this conclusion.
Comment
EPA states on page 4 of the Proposed Plan that "the COCs identified in OUs 1 & 6 are
the result of liquids from the buried waste pits and leachate from the buried refuse. "
There is absolutely no evidence that refuse at the Site contributed to contamination 01
media in OUs I & 6, nor is there any evidence that any liquids were generated or
infiltrated through municipal waste at Lowry.
Response
There is evidence that refuse may have contributed and could continue to contribute to
contamination of media in OUs 1 & 6. As stated in the draft RI report for OUs 2 & 3,
up to 2,700 cubic feet of water per year could be percolating through the landfill. On the
basis of the results of the column leachate study, the flux from the landfill mass based on
this flow is estimated at 34,980 mg/day of toluene. These estimates are based on the
current condition where the landfill has a clay cap covering it. In the past, before the cap
was placed, even more liquid would have percolated through the landfill.
There is also evidence that liquids were generated, or infiltrated, through municipal waste
at the Lowry Landfill site since small quantities of leachate have been noted to exist
within the unsaturated landfill mass during site investigations.
Comment
In the first bullet in the discussion of the Baseline Risk Assessment, EPA discusses futUre
onsite residents and future use of onsite ground water. Denver, as owner of the Site,
regards future onsite residents or residential ground-water use as extremely unlikely. In
1991, Denver's mayor issued Executive Order No. 97, which placed restrictions on the
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use of land, suiface water, and ground water at the Site. These restrictions included the
following:
.
No direct use or reuse shall be made of the ground water in the Denver or
Dawson aquifers underlying the Site that could cause exposure of humans
or animals to contaminants in said water.
.
No direct use or reuse shall be made of ground water in the Arapahoe and
Laramie-Fox Hills aquifers underlying the Site for domestic, residential, or
municipal water supply purposes.
.
The Site shall not be used for agricultUre, residential development, or com-
mercial development.
Executive Order No. 97 officially states the policy of Denver regarding use of its
property. This policy has been followed since the adoption of the executive order by both
the Pefia and Webb administralions. In view of the identified health risks at the Site and
Denver's commitment as a governmental entity to the protection of human health and the
environment, this policy is not expected to change.
To further address concerns over the permanence of these controls, Denver Mayor Webb
recently committed to formalizing these controls such that they were permanently enforce-
able by a responsible third party. Denver has recently proposed language to EPA and
CDH for a declaration of covenants to run with the land. In the proposed covenants,
EPA and CDH, as well as Denver, have enforcement aUthority to restrict land and
ground-water use at the Site.
Response
Denver appears to be suggesting that EP A should not have used a residential-use scenario
in the Baseline Risk Assessment because of Executive Order No. 97. It is EPA's policy
not to consider institutional controls when conducting Baseline Risk Assessments.
Furthermore, EP A has made a risk management decision to retain the residential scenario
when evaluating remedial alternatives because there is residential development in the area
and the ground water will potentially be used for residential consumption. For this and
other reasons, EP A has determined that it is reasonable to assume that the Site could be
used for residential purposes in the future.
As stated in the risk assessment for OUs 1 & 6, Executive Orders may be overturned by
this or any future administration, and therefore do not qualify as permanent enforceable
institutional controls. EPA acknowledges Denver's recent proposal for covenants to run
with the land and agrees that this type of institutional control may meet some of EPA's
concerns about permanent enforceability. As described in the ROD, offsite institutional
controls shall serve as an additional measure of protection to enhance the effectiveness of
the selected remedy and to act as preventative measures to preserve the implementability
and effectiveness of any of the selected remedy contingency measures. Offsite
DENIOO153A4.WP5
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institutional controls shall include, but not be limited to, deed notices and restrictions,
zoning controls, and well restrictions. These controls must prohibit all offsite activities
in the vicinity of the Lowry Site that would interfere or be incompatible with, or that
would in any way reduce or impair the effectiveness or protectiveness of, the selected
sitewide remedy.
Comment
In the second bullet discussing the Baseline Risk Assessment, it should be noted that con-
taminants in offsite ground water posing an unacceptable health risk are not anticipated
for at least 50 years.
Response
The 50-year estimate is solely an estimate. Given the uncertainty associated with
numerical models, EP A believes is prudent to assume a wide margin of error with respect
to numerical predictions.
Comment
EPA, on page 4, states that "Executive Order No. 97, as issued by the City and County
of Denver, would be enforced." Who does EPA anticipate will enforce these land-use
restrictions? Have these enforcement costs been included in the total remedial costs?
Response
Since Executive Order No. 97 was written and signed by the Mayor of Denver, EPA
expects that Denver would use its enforcement authorities to ensure that the components
of the Order are fol1owed. Furthermore, the land is owned by Denver. Enforcement
costs for implementing this Executive Order have not been included in the cost of
remedy. EP A does not know if the City of Denver has an enforcement budget to enforce
this Executive Order.
Comment
EPA should explain the discrepancies betWeen its Modified Alternative No.5 described in
the Proposed Plan, and Alternative No.5 as described in the OUs 1 & 6 FS.
In the FS, east and west boundary conJainment is composed of 1 DO-foot-deep wells, while
in the Proposed Plan, east and west containment is composed of 5O-foot-deep wells 07
collection systems. Also, the extent of the southern portion of the west boundary system
is dissimilar.
EPA should clarify if the Lowry Coalition's assumptions about the use of wells is included
in Modified Alternative No.5. If not, and the lateral control systems consist of barrier
walls, collection trenches, or other engineering control, then the costs quoted for the
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lateral control systems are not correct. At a minimum, if EPA intends to delay the
decision about the proper engineering control until remedial design, then a sensitivity
analysis of cost impacts of differing designs would be appropriate.
EPA apparently has used the Lowry Coalition's present value cost estimate for Alternative
No.5 as the basis for its present cost for Modified Alternative No.5. It is important to
note that Alternative No.5, as priced in the OUs 1 & 6 FS, had lateral control systems
that solely consisted of wells that are monitOred over time, with no money ever allocaled
for electricity, well maintenance or replacement, or treatment of the collected ground
water. WMC/CWM/Denver support the idea of monitoring the east and west boundaries
for contamination, without implementing remedial action prior to arrival of contaminants,
particularly given the OUs I & 6 ground-water modeling results, showing that
contamination is not expected at the east or west boundary for at least 50 years. Any
premature pumping of these systems may exacerbate the potential for lateral ground-water
contamination.
Response
EPA has modified Alternative 5 from the FS and has renamed it Modified Alternative 5.
The modifications consist of an additional upgradient containment/collection and/or
diversion system on the southern boundary of Section 6 of the Lowry Landfill Superfund
Site.
In Appendix C of the FS Report dated October 1992, the Lowry Coalition provided cost
estimates for depths of 50, 65, and 100 feet for extraction trenches. EPA has determined
that 50-foot depths will fulfill the functions of the barrier wall and/or collection system,
in that the weathered Dawson is believed to be the primary pathway of contaminant
migration. The weathered Dawson"s depth does not exceed 50 feet.
EP A modified the southern portion of the western boundary to be closer to the source
area and thus captures the migration of contamination closer to the source.
EPA used the assumptions outlined in Table 5.14 in the FS Report dated October 1992.
EPA developed a cost estimate for Modified Alternative 5 based upon a 50-foot depth
barrier wall and the same length as shown in Figure 5.51 in the FS Report. EP A
requires that cost estimates for the final FS should be in the range of + 50 percent/
-30 percent range. The Modified Alternative 5 has been completed within this range.
Table 5.14 of the FS Report shows costs for electrical power, well replacement, well
maintenance and well cleaning with acid. Tables C3 and C5 show start-up costs and
operation and maintenance costs for the treatment plant. Based upon the January 1993
Compliance Boundary Sampling event, there is confirmed contamination in B301A and
B216A at the western boundary of the Site. Therefore contaminants have migrated to the
compliance boundary and rem~iation is required. EPA agrees that if extraction wells
were used, pumping could cause lateral contaminant migration. This supports the
selection of barrier walls over extraction wells.
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Comment
EPA should explain why the southern boundary in the Proposed Plan is designed to a
50-foot depth, while in HLA's response to EPA comments on the FS, the southern boun-
dary is designed to a 60-foot depth.
Response
See response to the above comment.
Comment
EPA should explain the technical basis for the upgradient containment, collection, and/or
diversion system. The design and cost for the system described in the Proposed Plan is
dissimilar to that contained in the Responsiveness Summary to EP A comments on the draft
FS report.
Response
The upgradient system proposed to control the flow of ground water into the Site is
conceptualized to intercept clean ground water flowing from the south into the Site. It is
anticipated that the system will be composed of a barrier wall and an extraction system.
A barrier wall will limit the impact of the extraction system on the ground-water
hydraulic gradients inside the Site.
The additional cost associated with the upgradient system is anticipated to be approxi-
mately $2 million. This cost will be offset by the benefits derived from the upgradient
system. The following benefits have been identified:
.
Enhanced isolation of site contaminants. January 1993 sample results
along the southern boundary confirmed contamination that exceeds the
preliminary remediation goals.
.
Prevention of offsite contamination migration, which may occur through
the unidentified sand stringers/sand channels and other geologic
heterogeneities.
.
Mitigation of contaminant migration on the south, resulting from localized
ground-water flow to the south, chemical diffusion, dispersion, or possible
unidentified, localized seasonal changes in ground-water flow direction.
.
Prevention of most clean ground water from entering the contaminated site,
thus reducing the treatment cost associated with other onsite collection
systems.
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Modified Alternative 5 costs are different from those for Alternative 7B in the
responsiveness summary because Modified Alternative 5's cost estimate was developed by
EPA.
Comment
EPA should state that the present value costs calculated for the preferred alternative are
greatly influenced by the financial assumptions made. EPA has assumed in its costing, as
did the OUs 1 & 6 FS documents upon which EPA relies, a "real interest rate" of
5 percent over the next 30+ years (real interest meaning the difference between the
discount rate and inflation).
EPA should carefully consider the aggressiveness of its financial estimates. It is unlikely
that one could invest monies today and earn, after taxes, a 5 percent greater return than
inflation. This point is readily apparent today, when inflation is running at approximately
4 percent per annum. EPA's financial assumptions would mean that one would have to
generate a 9 percent return on investment, after taxes. If a PRP were paying 38 percent
taxes, then EPA's financial assumptions would be that a PRP would have to make about a
14.5 percent pretax return on investment. Given that commercial paper in today's market
is yielding only approximately 3.5 percent, EPA's aggressive financial assumptions must
be questioned.
Response
EPA agrees that the present worth analysis is influenced by the assumed discount rate and
timing of expenditures. However, the purpose of the present worth analysis is to
compare the alternatives on a relative basis, not to determine the total PRGs cost of any
remedy with a high degree of accuracy. The accuracy of the estimate for each individual
remedy is subject to substantial variation since little detail is known about the specific
design of each alternative. Typically, such "order-of-magnitude" estimates are expected
to be no more accurate than roughly -30 to +50 percent.
In reviewing this comment, EP A performed an approximate check to assess whether or
not the chosen present worth discount rate would affect the relative ranking of the
alternatives on a cost basis. The method was only an approximation and used the fol-
lowing procedure:
1.
Capital costs, annual O&M costs, and implementation times were taken
from the Proposed Plan.
2.
Capital costs were assumed to occur in two or three equal amounts at the
end of each of two or three implementation years as given in the Proposed
Plan. For example, for Alternative 2 (capital cost = $9,819,000; time to
implement = 2 years), an expenditure of $4,905,500 was assumed at the
end of year 1 and year 2.
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3.
O&M costs were assumed to occur at the end of each of 30 years succeed-
ing the final year of implementation. For example, for Alternative 2 an
expenditure of $1,816,000 was assumed to occur for 30 years, beginning at
the end of year 3.
4.
The present worth of the capital and O&M expenses were calculated at the
beginning of year 1, then summed.
The results are presented in the attached table.
Since the flows for capital costs projected by the PRPs' consultants, HLA, were more
detailed than the simple equal annual amounts used in the above procedure, the calculated
present worth for 5-percent discount rates are not identical. However, they are all within
8 percent, which is well within the expected accuracy of the estimates.
A comparison of the calculated present worth for each discount rate shows that, in all
cases, the relative ranking of the alternative costs remains the same.
The selection of a discount rate for present worth analysis is not intended to predict
future interest rates, tax effects, or other financial factors. A present worth analysis is
simply a technique to permit relative comparison of options on a cost basis. The actual
cost of the selected remedy may vary depending on many factors, including design
details, bidding climate, changes during construction and operation, interest rates, labor
and equipment rates, inflation, tax effects, and similar items that neither EPA nor the
PRPs can control.
Comment
The OUs 1 & 6 FS cost estimates are only for a duration of 30 years. It is highly
unlikely that remedial action at the Site will terminate in 30 years. As EPA stated in its
comments on the OUs 1 & 6 draft FS report, "the ground-water model indicates that
dissolved contaminants will increase risks up to 800 years." EPA should address the
length of the remedial action necessary, and state its long-term impact upon the cost.
Response
The treatment of contaminated ground water is likely to continue in perpetuity. The
impact to the cost can be estimated using the same O&M and discount rate for the length
of time desired. The Lowry Coalition has provided tables in Appendix H of the FS
Phase 3 Report that describe how the present worth costs are derived. The PRP would
need to invest less than $5,000 today to be able to fund $107,000 of O&M 63 years from
now using a 5 percent discount rate. The amount needed to be invested today for O&M
needed 800 years from today is negligible.
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......
v.>
I
......
IV
......
Table 13-1
Lowry Landfill, Arapahoe County, CO, Operable Units 1 and 6, Proposed Plan, Effect of Discount Rate on Cost Estimates
PWin Present Worth of Capital + O&M Costs ($000)
Time to Proposed Discount Rate (percent/annum)
Implement Plan
Alternative (yrs) ($000) 2 4 S 6 8 10 12 14
No Action 0 0 0 0 0 0 0 0 0 0
1 0 31,000 45,976 36,706 33,220 30,301 25,748 22,423 19,932 18,021
2 2 36,000 49,959 39,284 35,314 32,008 26,881 23,152 20,357 18,203
3 3 56,000 77,916 60,188 53,653 48,237 39,898 33,883 29,409 25,984
4 3 101,000 129,512 108,969 101,205 94,652 84,260 76,420 70,296 65,362
5 3 59,000 80,859 62,872 56,232 50,725 42,231 36,088 31,505 27,985
Modified 5 3 61,000 85,074 66,712 59,921 54,281 45,562 39,235 34,495 30,840
6 3 66,000 91,181 70,988 63,533 57,347 47,803 40,898 35,744 31,782
PW = Present worth costs
O&M = Operation and maintenance
DENI00153CB.WP5
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Cominent
EPA's preferred alternative requires constructing collection systems at the east and west
boundaries. The design life of these collection systems using extraction wells is assumed
to be 4 years in the FS. If contamination requiring remediation is not anticipated at the
east and west boundaries for at least 50 years, the extraction wells will need to be
replaced 12.5 times before they are needed. Construction of the collection systems at this
time is certainly not cost-effective.
Response
The FS assumes 25 percent of the wells would be replaced every 4 years, therefore the
design life of anyone well could be as little as 4 years and as much as 16 years. Most
current wells at the Site are about 10 years old and do not require abandonment and
replacement. Based upon the January 1993 Compliance Boundary Sampling event, there
is confinned contamination in B301 A and B216A at the western boundary of the Site.
Therefore containments have migrated to the compliance boundary and remediation is
required.
Comment
EPA's preferred alternative shows a new ground-water treatment facility, the purpose of
which is to treat high-concentration fluids extracted from the ground-water collection sys-
tem at the northern toe of the existing Section 6 landfill mass. While treatment of fluids
from this extraction system will be necessary, it may be possible to adequately treat these
fluids at the existing upgraded treatment plant, or to modify the plant. EPA should not
require a new treatment plant, but rather should allow the need for a new treatment plant
versus the existing plant (or modification thereof) to be fully evaluated during remedial
design.
Response
The selected sitewide remedy must meet the performance standards, including ARARs.
Whether this is achievable via modification of the existing plant, or whether a new plant
must be constructed, will be determined by EPA during RD.
Comment
EPA has chosen modified Alternative No.5, in part, because of its increased reduction of
contaminants over other alternatives. However, modified Alternative No.5 represents a
doubling of the 3D-year present worth costs over the No Further Action Alternative. The
cost/benefit of this doubling should be weighted against the fact that nearly 80 percent of
the contaminants of concern will remain in the subsurface after 30 years (calculated by
multiplying the mean concentration of COC in the weathered system, as reported in the
OUs 1 & 6 final RI report, by the volume of contaminated ground water, then dividing by
the anticipated rate of COC removal rate of 700 pounds per year).
DENIOOIS3A4.WPS
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Response
EPA's selection of Modified Alternative No.5 shows EPA's commitment to prevent
migration offsite while simultaneously treating to the maximum extent practicable and still
be cost-effective.
Comment
In its Responsiveness Summary on the draft FS report, HLA indicated that the south
boundary system will intercept about 21,000 gallons of ground water per year. HLA also
calculated in the R1 report that the Site contains in excess of 900 million gallons of con-
taminated liquids. Preventing 0.002 percent of the conlamino.ted ground-water volume to
flow into the Site seems insignificant when compared to the total volume of contaminated
ground water at the Site. EPA should provide a cost/benefit analysis of the southern
barrier.
Response
EPA believes that the estimated 21,000 gallons of ground water per year expected to be
intercepted by the south boundary system will constitute substantially more than
0.002 percent of the contaminated water at the Site since the 900 million gallons of
contaminated liquids will not all be extracted within a year. As discussed earlier, south
boundary water interception is one of many benefits of the south boundary system.
The benefits derived from tJoe upgradient system at an additional estimated cost of
$2 million are as follows:
.
Enhanced isolation of site contaminants. January 1993 sample results
along the southern boundary confinned contamination that exceeds the
preliminary remediation goals.
.
Prevention of offsite contamination migration, which may occur through
the unidentified sand stringers/sand channels and other geologic hetero-
geneities.
.
Mitigation of contaminant migration on the south, resulting from localized
ground-water flow to the south, chemical diffusion, dispersion, or possible
unidentified, localized seasonal changes in ground-water flow direction.
.
Prevention of most clean ground water from entering the contaminated site,
thus reducing the treatment cost associated with other onsite collection
systems.
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13.2.10 EP A Response to Comments from
Wilbur A. Young
Comment
The commentor expressed a concern over the PRPs' commitment to protecting the
environment.
Response
Many PRPs at the Lowry site have been responsive in answering questions regarding the
types and amount of waste materials deposited at the Lowry Site in their 104(e)
responses. In addition, certain PRPs have performed RI/FSs at the Site, and have
implemented interim remedial measures such as the installation of the barrier wall and
construction of a ground-water treatment facility to stop northward migration of
contaminants.
Comment
The commentor also expressed a concern over the potential risks to human health and the
environment posed by the Site.
Response
A risk assessment was performed to assess potential human health problems, and an
ecological risk assessment was conducted to assess potential adverse effects on wildlife
and plants. The cleanup strategy is protective of human health and the environment.
The remedial investigation describes the fate and transport of chemicals at the Site,
including degradation products. The risk assessment, which is based on results of the
Remedial Investigation, addressed both cancer risks and adverse chronic health effects
from chemicals at the Lowry Site.
Comment
The commentor expressed concern over the PRPs 7 commitment to environmental regula-
tions and laws.
Response
See response to fIrst comment, above.
Comment
The commentor was concerned aboul individuals coming forth to provide the government
additional information about dumping at Lowry.
DENlOOI53A4.WP5
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Response
EPA has received information, both official (as in the 104(e) responses) and unofficial
(such as anonymous reports of dumping).
Comment
The commentor stated that Modified Altema.r.ive 5 is the best altemaJive based on cost.
Response
EPA acknowledges support of the preferred remedial alternative for OUs I & 6 as
expressed in the Proposed Plan.
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Section 14.0
Responsiveness Summary for Operable Units 2 & 3 and 4 & 5
-------
Section 14.0
Responsiveness Summary for Operable Units 2&3 and 4&5
This section presents the oral and written responses to comments from EPA to
individuals, concerned citizen groups, and public entities who have commented on the
Proposed Plan for ODs 2, 3, 4, and 5. Comments are expressed in italics; their
responses in plain text.
14.1 Response to Oral Comments
Proposed Plan Public Meeting
Lowry Landrill Solids/Gas Operable Units (OUs 2&3) and
Soils/Surface Water and Sediments
Operable Units (OUs 4&5)
September 21, 1993
The following is a summary of citizens' comments received at the September 21, 1993
Proposed Plan Public Meeting for ODs 2, 3, 4, and 5. The responses given at the public
meeting are also listed, and in some circumstances have been expanded for a more
detailed explanation.
1.
Comment
How much of the capital costs for cleanup have already been incurred for such items as
the Suiface Water Removal Action?
Response
The costs of the interim measures including the Surface Water Removal Action, the
ground-water barrier wall and treatment facility, and the tire shredding operation, have
already been expended and are not included in the total capital costs for the various
remedial alternatives.
The approximate cost of the Surface Water Removal Action was 1.5 million dollars. The
approximate cost of the shredding operation was 2.3 million dollars.
2.
Comment
Who is in charge of maintenance for theftrst 30 years and what happens after 30 years?
Does EPA walk away?
DENlOO153C7.WP5
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Response
Maintenance of the site for the fIrst thirty years, and thereafter, is the responsibility of
the Potentially Responsible Parties (pRPs) that sign up to implement the remedies under
the supervision of EP A and the Colorado Department of Health. EP A often uses a
standard period of 30 years to estimate operation and maintenance costs, so that
comparisons can be made between alternatives and between all Superfund sites. For
Lowry Landfill, the lifespan of the sitewide remedy may very well exceed 30 years.
3.
Comment
Why aren't all the responsible parnes being held accountable for the cost of paying for
cleanup at Lowry? Who will pay for the cleanup?
Response
Under Section 107 of the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980, as amended (CERCLA), current owners and operators, past
owners or operators, transporters and/or generators are liable for cleanup costs incurred
by the United States or a State at a Superfund site. EP A considers each of these
Potentially Responsible Parties (pRPs) to be jointly and severally liable for the costs of
cleanup at the Lowry Landfill site.
The City and County of Denver (Denver), Waste Management of Colorado, Inc. (WMC),
and Chemical Waste Management, Inc. (CWM) have negotiated private settlement
agreements with many of the other PRPs at the site. Although the terms of those
settlements have not yet been made available to EP A, Denver and WMC/CWM have
indicated that they intend to perform the cleanup of the site and use monies collected
under the private settlement agreements to reimburse the United States for past and future
response costs incurred at the site.
4.
Comment
How much of an excavational alternative was considered? Does the excavation
alternative include all six operable units? The reason it wasn't financially viable in part
was because Waste Management put six years of trash on top of the Supeifund site?
Response
Excavation of the Lowry Landfill was evaluated in a Technical Memorandum,
Preliminary Identification of Remedial Alternatives, dated April 15, 1988. At that time,
it was determined that it was not fmancially viable or practical to excavate the entire site.
In addition to ground-water treatment, the excavation alternative included excavating the
entire site, incinerating the solids and soils onsite, and disposing of the incinerated ash
offsite. Estimated total capital and operation and maintenance costs for the excavation
DENIOOI53C7.WP5
14-2
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alternative would exceed $4.5 billion. Additionally, the volume of ash would be on the
order of 40 percent of the incinerated material. Disposal of the ash would take over
19 years with a dump truck full of ash leaving every half hour, every day of the year.
Onsite worker exposure to hazardous materials was also determined to be a high safety
risk. The excavation analysis that was performed applies to the entire site, and therefore
to all six operable units in combination.
The proposed excavation for the former tire pile area does not address all six operable
units; it only addresses a portion of operable unit 2 (landfill solids).
The additional trash placed on the landfill from the time that it became a Superfund site
(September 1984) to the last time trash was placed on the site (August 1990) was taken
into consideration during EPA's evaluation of cleanup proposals. EPA does not endorse
the proposal to place an additional 1.2 million cubic yards of municipal solid waste on the
Lowry Site, as has been proposed by Waste Management of Colorado, Inc.
5.
Comment
How does the ground-water treatment system work?
Response
Contaminated ground water is collected at the barrier wall and pumped to the on site
treatment facility. At this facility, ground water is first processed through an airstripper.
As the contaminated ground water passes through the airstripper, contaminants volatilize
(turn into a gaseous phase) and are removed from the water. These volatilized
contaminants are then collected on granular activated carbon. The liquid that flows out
of the airstripper is sent through a series of granular activated carbon units for additional
treatment. The treated water is injected into the shallow ground-water system
downgradient of the barrier wall.
If the collected ground water is observed to exceed concentrations above federal and state
standards, a contingency plan for ground-water treatment will be implemented. The
contingency plan includes a bioreactor and an ion exchange unit to remove ketones and
metals/radionuclides, respectively, from the collected ground water.
6.
Comment
Will new wetlands be constructed?
Response
During the Remedial Investigation for Operable Units 1 and 6, wetlands were identified
in the former Unnamed Creek drainage. As a result of the construction of the Surface
Water Removal Action, these wetlands were eliminated. New wetland habitats
DENlOOlS3C7.WP5
14-3
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(0.87 acres) will be constructed to replace the wetlands that were lost. The final location
of the wetl311ds will be specified during the Remedial Design phase.
7.
Comment
What types of contaminants were found in the water?
Response
For this response, it is assumed that the commentor was referring to ground water at the
site. A list of chemicals found in ground water, and their reported concentrations in the
ground water at the site, is provided in Table 14-1.
8.
Comment
Would vitrification be a viable cleanup alternative for the Lowry Site?
Response
No. Vitrification is a process in which electric probes are inserted into contaminated
soils. The targeted material is electrified to the point that it melts and then solidifies as a
"glass," rendering the contaminants immobile. Because of the presence of methane and
other gases in the Lowry Landfill, the electric current used in the vitrification process
could result in explosions or fires. Also, the composition of the landfill mass varies
significantly (trash, garbage, liquids, etc.) and makes it unsuitable for heating, melting,
and solidification.
9.
Comment
In the cancer risk assessment for sediments, it appears that the risk is higher north in
Murphy Creek than in Section 6. Why?
Response
First, it should be noted that the area identified as "north in Murphy Creek" is in fact
within Section 31. Two factors contribute to the higher future risk estimates identified
for the sediments in Section 31. First, the land use scenarios employed for Section 6
were different than for Section 31. To assess the potential risks, a combined residential!
recreational scenario was used for Section 31, while a recreational only scenario was used
for Section 6. This approach was based on the assumption that there would likely be
restrictions on residential land use for Section 6.
For Section 31 sediments, ingestion and inhalation exposures were calculated for both
future offsite residents (children and adults) and offsite recreational users. Risk
assessment calculations for the sediments in Section 6 were estimated based on ingestion
DENIOOIS3C7.WPS
14-4
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exposures to future onsite recreational users (children and adults) only. In estimating
potential health risks, exposure periods and contact times are typically higher for
residential scenarios than for recreational scenarios. Consequently, calculated health risks
may be expected to be higher for calculations in which a residential scenario is used.
Second, the contaminants identified in Section 6 sediments differed, in some cases, from
those identified in Section 31 sediments. The contaminants that contributed the highest
proportion of the estimated risk (from ingestion) for Section 6 sediments included arsenic,
beryllium, and antimony. For Section 31 sediments, the contaminants that contributed
the greatest proportion of estimated risk (from ingestion and inhalation) included arsenic,
dioxins, chromium, beryllium, manganese, and vanadium. Several of the contaminants in
Section 31 sediments possess relatively greater chronic toxicity characteristics than those
contaminants found in Section 6 sediments. As a result, the calculations resulted in a
higher relative risk estimate. The observed concentrations, and resulting risk
calculations, were similar to those for background (naturally occurring) sample
concentrations.
10.
Comment
Are any of the pollutants in the landfill recyclable, like the methane?
Response
Heat recovery from flaring of methane gas in the landfill was analyzed in the Feasibility
Study for OUs 2&3. However, it was determined that since the landfill is physically
distanced from any potential heat users, it would not be financially viable to extract the
gas at this time. Additionally, there are individual contaminants such as vinyl chloride in
the methane which would have to be removed before the methane could be used for
beneficial purposes. At this time, no other pollutants in the landfill are believed to be
recyclable.
11.
Comment
It seems that a combination of land use restrictions/acquisitions and excavation of the
landfill in the areas where it would be effective, would be the best possible solUtion.
Response
The comment is noted by EPA. While EPA's preference is to implement a cleanup
approach that does not rely on offsite institutional controls such as land use restrictions,
restricting landuse around the site would add an extra measure of protection to the
general public.
DENlOOI53C7.WPS
14-5
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12.
Comment
What is done with the asbestos?
Response
Asbestos is disposed of in the asbestos pit, which is located in the northwest portion of
Section 6. Asbestos must enter the landfill in sealed containers or double bags, and is
buried and covered on a daily basis. This asbestos disposal operation is regulated by the
Colorado Department of Health.
13.
Comment
What are the costs in addition to the $ 97 million?
Response
The Present Worth Cost estimate of $97,510,000 is for design, construction, and
implementation of the Selected Sitewide Remedy. In performing calculations for
engineering cost estimates, factors of -30 percent and +50 percent are typically included
to account for unforeseen aspects of a project. Therefore the total cost of cleanup may
range from $68,257,000 to $146,265,000.
The additional costs that have been incurred in connection with the site are approximately
$60 to $70 million (this range represents a further refinement from that which was
provided at the public meeting). These costs include, but are not limited to: EPA past
costs (including Phase I & IT studies, the Baseline Risk Assessment, oversight); and costs
incurred by potentially responsible parties (pRPs) during implementation of interim
remedial measures and the remedial investigations and feasibility studies. In many cases,
because PRPs were not legally required to supply EPA with records of their
expenditures, costs incurred by those parties could only be estimated.
14.
Comment
What are the discount rates and inflation rates used to determine the present worth on the
cleanup costs?
Response
The real net discount rate used for cost estimating purposes is 5 percent. This rate
assumes the difference between the discount rate and inflation is 5 percent. This is the
standard rate recommended by EP A for estimating present worth remediation costs.
DENlOOlS3C7.WPS
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15.
Comment
Who was the largest polluter at the Lowry Site?
Response
The Adolph Coors Company is estimated to have disposed of the largest volume of
waste, approximately 32 million gallons. The Lowry Landfill Waste-In List (dated
April 17, 1992), which is a listing of generators, transporters, owners, and operators for
the Lowry Landfill Superfund Site, may be obtained from the EP A Superfund Records
Center.
16.
Comment
What happens at the 5-year review? Has EPA ever ordered additional remediation at a
site as a result of the 5-year review?
Response
CERCLA Section 121(c) mandates that EPA review remedial actions which result in any
hazardous substances, pollutants, or contaminants remaining at a Superfund site, no less
often that each five years after the initiation of the remedial action. This requirement
assures that human health and the environment are being protected by the remedial action
being implemented. EP A will continue the reviews until no hazardous substances,
pollutants, or contaminants remain at the Lowry Site above the remediation levels that
allow for unrestricted use and unlimited exposure. Since protectiveness at the Lowry Site
will be assured through containment and onsite institutional controls, the review will
focus on the effectiveness of these measures. In addition, because the sitewide remedy
contains a long-term remedial action, the review will also evaluate the effectiveness and
performance of the technologies used in the remedy. The review will examine
information such as monitoring data, applicable or relevant and appropriate
requirements, remediation levels, and new information or considerations relevant to an
assessment of protectiveness.
To date, there have been two 5-year reviews conducted for sites in EP A Region VIII:
Chemical Sales Company Superfund Site; and Rose Park Sludge Pit Superfund Site. Both
of these reviews concluded that human health and the environment are being protected by
the remedial actions being implemented. However one of the reviews recommended that
additional institutional controls, in the form of deed restrictions, be implemented.
DENlOOlS3C7. WPS
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For further information on 5-year reviews conducted in other EP A regions, please
contact:
DENlOOlS3C7.WP5
Mr. Hugo Fleischman, 5203-6
u.s. Environmental Protection Agency
Office of Emergency and Remedial Response
Hazardous Site Control Division
401 M Street, SW
Washington, D.C. 20460
(703) 603-8769
14-8
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Response to Specific Oral Comments from
The City and County of Denver (Denver),
Waste Management of Colorado, Inc. (WMC), and
Chemical Waste Management, Inc. (CWM)
Landfill Solids
1.
Comment
The Feasibility Study (FS) fully evaluated waste pit removal and did not recommend it
because of health and safety concerns. Specifically, this remedy would create potential
for high level risk to workers during excavation and removal of those materials.
Response
The Feasibility Study (FS) for the landfill solids operable unit (OU2) did not identify
health and safety concerns as a major issue for waste pit removal. The FS for OU2 did
discuss short-term effectiveness for worker protection. The FS also presented air
modeling results, which were used to quantify worst-case potential and actual risk
scenarios. These scenarios modeled volatile organic compound (VOC) releases resulting
from excavation work in the former tire pile area. Under the assumption that all of the
emissions were pure vinyl chloride and that a worker was exposed continually without
protective wear, the lifetime excess cancer risk was estimated to be 2 x 10-5. This value
is within the acceptable cancer risk range established for Superfund sites.
For further discussion on this issue, the reader is referred to the response to Written
Comment 20 from Denver/WMC/CWM.
2.
Comment
The only existing exposure pathways are through direct contact. The direct contact at
this time is precluded because these materials are separated from the suiface by an
engineered drainage system.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
23 from Denver/WMC/CWM.
3.
Comment
Any hopes of recovering drums of liquids to be shipped offsite and of finding perched
liquids in old waste pits are probably misplaced.
DENlOOlS3C7.WPS
14-9
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Response
For a discussion on this issue, the reader is referred to the response to Written Comment
21 from DenverlWMC/CWM.
4.
Comment
A remedy to collect and treat any releases from these drums and waste pits is now in
place and has been operating for the last 10 years.
Response
To the extent that the commentor was referring to the barrier wall and treatment plant, it
must first be noted that these facilities have been in operation for less than ten years. It
is true that the these facilities, combined with the Surface Water Removal Action
collection system, are intended to prevent offsite migration of contaminated ground
water. These systems by themselves do not provide the degree of protection that is
afforded by addressing source areas or that is warranted by the site risks. The intent of
the preferred alternative for OU2 is to eliminate or reduce the source of the
contamination by excavating drums, drum contents, and contaminated soils.
For further discussion on this issue, the reader is referred to the response to Written
Comment 22 from DenverlWMC/CWM.
5.
Comment
WMC/Denver are concerned during construction about the potential for a significant
ground water recharge event from ponding that may occur during excavation that would
carry any contaminants that might be found down into ground water.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
24 from Denver/WMC/CWM.
6.
Comment
WMC/Denver are concerned that this selected remedy does not comply with EPA's
Landfill Guidance.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
25 from Denver/WMC/CWM.
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7.
Comment
The capping alternative fully complies with all laws and guidance and would create no
short-term or long-term health risk. The FS recommended improving the cover over the
landfill by adding more municipal solid waste (MSW) to increase the slope of the cover.
The additional solid waste will add a very small increment of mass to the waste now in
place.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
33 from Denver/WMC/CWM.
In addition, the community and local governmental entities oppose Alternative 7 for OU2.
Community acceptance is one of the nine evaluation criteria to be evaluated in the
alternative selection process.
The proposed volume of additional MSW (1.2 million cubic yards) represents
approximately 10 percent of the waste in place. To the extent that the landfill cap
requires repairs, there are a variety of other engineering options that will be evaluated
during RD, for example, to minimize any existing surface drainage problems.
Landfill Gas
8.
Comment
WMC/Denver strongly believe the staged approach is the most protective of human health
and the environment.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
34 from Denver/WMC/CWM.
9.
Comment
Denver/WMC/CWM are concerned aboUt the specificity in the Proposed Plan for OUs 2,
3, 4, and 5 (i.e., number of wells).
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Response
For a discussion on this issue, the reader is referred to the response to Written Comment
35 from Denver/WMC/CWM.
10.
Comment
WMC/Denver believe that tire preferred alternmive for OU3 would cause undue delay in
tire collection and treatment of gas at tire site.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
34 from Denver/WMC/CWM.
11.
Comment
The Proposed Plan for OUs 2, 3, 4, and 5 unnecessarily modifies Landfill Gas
Alternative 3, as presented in tire FS for OU3.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
34 from Denver/WMC/CWM.
12.
Comment
The Proposed Plan for OUs 2, 3, 4, and 5 unfairly compares tire preferred alternative for
OU3 to Stage 1 of tire Landfill Gas Alternative 3, as presented in the FS for OU3.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
34 from Denver/WMC/CWM.
13.
Comment
The Landfill Gas Alternative 3 and proposed permanent land use restrictions provide a
superior remedy.
Response
For a discussion on this issue, the reader is referred to the response to Written Comment
36 from Denver/WMC/CWM.
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14.2 Response to Written Comments
Proposed Plan
Lowry Landfill Solids/Gas Operable Units (OUs 2&3)
and Soils/Surface Water and Sediments Operable Units (OUs 4&5)
The following comments were offered in relation to the Proposed Plan for Operable Units
(OUs) 2&3 and 4&5. EPA has taken into consideration that the comments may pertain
equally or in greater degree to the selected remedy or to the Proposed Plan for OUs 1&6,
although the comments were not specifically offered in connection with the Proposed Plan
for OUs 1&6.
14.2.1
Response to Written Comments
Hadden and Bonnie Robinson
1.
Comment
The commentors expressed concern that the contents of the Lowry LandfiZZ are unknown.
Response
Characterization of the waste types disposed at Lowry Landfill was performed during the
remedial investigations of all six operable units. These investigations included the
evaluation of landfill operator and other waste disposal records, as well as the
performance of field studies. Over 2,000 samples of ground and surface water, soils, air,
and gas were collected and analyzed. The lists of the chemicals detected at the site may
be found in the remedial investigation reports for each of the operable units.
In general, the types of wastes disposed of at the Lowry Site prior to 1980 include such
materials as acid and alkaline sludges, caustics, brines, oils, greases, solvents, laboratory
wastes, construction debris, and municipal solid waste. Although it is true that a landfill
such as Lowry can contain substances not yet identified, the cleanup plan is designed to
keep all contaminants onsite.
2.
Comment
The commentors would lilre the Lowry Site to be cleaned up soon.
Response
EPA supports the commmenters' recommendation for expeditious cleanup. EPA has
recognized for several years the slow pace of Superfund cleanups and has taken actions to
expedite the process, including early actions to achieve stabilization of immediate
problems.
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Initial efforts to clean up the Lowry Site began in 1983 with the construction of the
ground-water barrier wall and treatment plant. These facilities prevent offsite migration
of contaminated shallow ground water within the alluvium of unnamed creek. Most
recently, contaminated seeps in unnamed creek were removed through the construction of
the Surface Water Removal Action (SWRA) collection system. The selection of the
cleanup remedy for the Lowry site has now been completed by the issuance of this
Record of Decision (ROD). Following the ROD, Remedial Design (RD) activities for the
overall sitewide remedy may proceed. It is anticipated that design of the cleanup will
begin in the summer of 1994 and that construction of the remedy may commence as early
as the fall of 1995.
3.
Comment
The commentors would like to see legislation that would prohibit expensive hazards like
the Lowry Site from ever occurring again.
Response
In 1976, Congress enacted the Resource Conservation and Recovery Act (RCRA). This
law became effective in 1980 and requires hazardous waste to be treated, stored, and
disposed of in such a manner as to minimize the present and future threat to human
health and the environment. Hazardous waste disposal was discontinued at the Lowry
Site in response to this law. RCRA was significantly amended by the Hazardous and
Solid Waste Amendments of 1984 (HSWA). To date, there are over 500,000 companies
and individuals that must comply with RCRA. If the RCRA program is effectively
implemented, there should be no new Lowry Landfill-type problems.
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14.2.2
Response to Written Comments
Wilbur Young, November 1, 1993 Letter
1.
Comment
The commentor is concerned that the responsible parties lUlve not been held liable for the
cleanup of the Lowry Site.
Response
Under Section 107 of the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980, as amended (CERCLA), current owners and operators, past
owners or operators, transporters and/or generators are liable for cleanup costs incurred
by the United States or a State at a Superfund site. EP A considers each of these
Potentially Responsible Parties (pRPs) to be jointly and severally liable for the costs of
cleanup at the Lowry Site. For a more detailed discussion of cost recovery efforts
involving liable parties, please see the Record of Decision.
The City and County of Denver (Denver), Waste Management of Colorado, Inc. (WMC),
and Chemical Waste Management, Inc. (CWM) have indicated that they intend to
perform the cleanup of the site and use monies collected under private settlement
agreements to reimburse the United States for past and future response costs incurred at
the Lowry Site.
2.
Comment
The commentor is concerned that too much time has been spent on stUdies and that action
needs to be taken soon.
Response
EP A acknowledges that the studies have taken a considerable amount of time to complete.
Initial site studies began in the early 1980s and were completed in early 1993. Studies at
the Lowry Site have involved the collection of over 2,000 samples of environmental
media. Adequate characterization of the nature and extent of contamination is an
essential step in a process that concludes with selection of the most appropriate cleanup
approach. Initial actions have been implemented, concurrent with these characterization
activities, to prevent offsite releases.
3.
Comment
The commentor expressed the belief that complete excavation and disposal should be
considered.
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Response
Excavation of the Lowry Site was evaluated in 1988 and it was determined that it was not
financially viable or practical to excavate the entire site. The costs for excavation,
incineration, and ash disposal were estimated to exceed $4.5 billion. Additionally, the
volume of ash would be about 40 percent of the incinerated material. Disposal of the ash
would take over 19 years with a dump truck full of ash leaving every half hour, every
day of the year (refer to Final Draft Technical Memorandum, Preliminary Identification
of Remedial Alternatives, Lowry Landfill Phase II RIfFS).
4.
Comment
The commentor expressed the belief that the problems should first be stopped at the
Lowry Site, then studied.
Response
The most immediate threats to human health and the environment at the Lowry Site have
already been addressed through implementation of interim cleanup actions. These interim
cleanup actions are described in the proposed plans and ROD. Such actions allow EP A
to address the more immediate dangers that might affect human health and the
environment while studies are being performed.
5.
Comment
The commentor would like to see that the best possible plan is achieved for the taxpayers.
Response
To obtain the best possible plan, EP A uses the following nine evaluation criteria: overall
protection of human health and the environment; compliance with applicable or relevant
and appropriate requirements (ARARs); long-term effectiveness and permanence;
reduction of toxicity, mobility, or volume through treatment; short-term effectiveness;
cost; implementability; state acceptance; and community acceptance.
The selected remedy will protect human health and the environment, meet ARARs, and
offers the best balance of tradeoffs among all nine evaluation criteria. This includes the
cost-effectiveness criterion because the selected sitewide remedy provides long-term
effectiveness and permanence through: collection/treatment of landfill gas; removal/
treatment of contaminated material from the former tire pile area; and containment,
collection, and treatment of contaminated ground water.
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14.2.3
Response to Written Comments
East Cherry Creek Valley Water and
Sanitation District (ECCV)
1.
Comment
The commentor believes that there are interactions between media, and that cleanup
actions for the landfill solids and gas can have a positive impact on ground-water quality.
Furthermore, the commentor stated that gas migration from the Lowry Site has the
potential of impacting ojJsite wells, pipelines, pump stations, and other infrastructures
owned and maintained by the ECCV.
Response
EP A agrees that interactions may occur between different contaminated media at the
Lowry Site and that cleanup actions for one medium may improve the quality of other
media. Prevention of off site gas migration will eliminate the potential contamination of
offsite subsurface soils and may reduce the potential adverse impacts to ground water. In
addition, the removal and treatment of an estimated 80,000 pounds of volatile organic
compounds (VOCs) per year through the gas extraction/treatment system will further
benefit the ground-water system through contaminant source reduction.
The uncontrolled migration of gas has the potential to impact infrastructures in the
vicinity of the Lowry Site. Modified Alternative 3 (Gas Collection/Enclosure Flare) was
specifically selected to address this problem through containment, collection, and
treatment. This alternative will prevent the offsite migration of gas.
2.
Comment
Although the commentor would prefer to see more of the contaminated landfill solids
treated and/or removed, the commentor understands the difficulties in accessing much of
this material. The commentor feels that the removal of the accessible drums and
contaminated soils in the tire pile area will significantly assist in achieving the National
Contingency Plan (NCP) cleanup criteria that call for long-term effectiveness of the
measures taken, and for reduction of toxicity and volume of waste. The commentor
ardently supports this component of the proposed plan.
Response
EPA acknowledges ECCV's support for the OU2 (landfill solids) selected remedy. The
selected remedy achieves long-term effectiveness and permanence, as stated. The
selected remedy is also consistent with EP A's Guidance for Conducting Remedial
Investigatiom/Feasibility Studies for CERCLA Municipal Landfill Sites. This guidance
recognizes that containment is generally the most appropriate response action because of
the large volume and heterogeneity of the waste typically found within a landfill mass.
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This guidance also supports "hot-spot" removal where wastes are accessible, to achieve a
decrease in. the risk posed to human health or the environment.
3.
Comment
The commentor is opposed to adding municipal solid waste on top of the former landfill
as a means of drainage control.
Response
EPA and CDH agree that municipal solid waste (MSW) should not be added to the
former landfill mass. CDH considers the former landfill to be closed and adding
additional MSW to a closed MSW landfill would not be consistent with the intent of the
new Subtitle D requirements. In addition, there are other engineering options that would
be equally effective in ensuring acceptable drainage control and that would not also add
additional solid waste mass to the Site.
4.
Comment
The commentor noted that Waste Management of Colorado, Inc. (WMC) and the City and
County of Denver (Denver) are currently in the process of optioning, or purchasing, all
of the land and water rights within a 1/2 mile buffer around the Lowry Site. The
commentor asked that EP A conduct an evalUation of the impact of this type of
institutional control (land acquisition) since it may be undertaken as part of a potential
cleanup strategy by WMC and Denver.
Response
At the public meeting on September 21, 1993, and in written comments on the proposed
plan for OUs 2, 3, 4, and 5, Denver and WMC indicated that they are considering the
purchase of property surrounding the Lowry Site. However, EP A has not been included
in any negotiations regarding options or purchase of land and water rights by Denver and
WMC. Offsite land use restrictions will provide an additional measure of protection
against exposure of human populations to contamination, would be important in the future
if additional measures are determined to be necessary under a contingency plan, and may
be necessary to ensure the integrity of the remedy.
5.
Comment
The commentor believes that no contamination should be allowed to migrate ojfsite.
Furthermore, the commentor believes that ojfsite standards should include the non-
degradation of the ground water and soil, rather than allowing contamination to migrate
ojfsite until Applicable or Relevant and Appropriate Requirements (ARARs) are reached.
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Response
The selected sitewide remedy is designed to prevent the offsite migration of contaminants
and thus offsite aquifer degradation. The selected sitewide remedy must ensure that
ARARs and other risk-based cleanup levels are achieved at the compliance boundaries.
CERCLA does not require clean up to zero levels or to below background concentrations
where MCLs and other ARARs provide numerical cleanup concentrations that are based
on acceptable risk. However, each component of the selected sitewide remedy includes
contingency measures to address offsite migration of contaminants.
In selecting a remedy, there are two threshold criteria: protection of human health and
the environment; and attainment of ARARs. EP A has set the acceptable risk range for
cancer incidents at Superfund sites at 1 x 10-4 (1 in 10,(00) to 1 x lQ-6 (1 in
1,000,(00).
However, at the Lowry Site, there may be cumulative risks posed by the potential
additivity of multiple contaminants or multiple pathways of exposure. Therefore,
circumstances at the Lowry Site require that the 1 x lQ-6 risk level be applied for
evaluating individual contaminants to ensure that the cumulative risk does not exceed
1 x lQ4, thereby ensuring the protectiveness of the remedy.
6.
Comment
The commentor asked what actions will be taken if chemical standards for ground water
change at some future date, and if the contamination spreads beyond the current site
boundaries.
Response
Chemical cleanup standards, or ARARs, are "frozen" at the time of the ROD. If new
information is obtained or if a regulation changes such that EP A determines the remedy is
no longer protective, the ROD would be amended to incorporate the new standard.
The performance standards will be re-evaluated at a minimum of every 5 years to ensure
that the remedy remains protective of human health and the environment. However, if at
any time contamination is detected above the ARARs (and other performance standards)
selected in the Record of Decision, appropriate action will be taken to achieve the ARAR
and to prevent the spread of contamination.
Appropriate action would include implementation of contingency measures that are
included in the selected sitewide remedy. These contingency measures would not only
prevent further contamination from occurring, but would also treat the contamination
until ARARs and risk-based concentration limits are achieved and maintained at and
beyond the Compliance Boundaries.
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Offsite institutional controls would further facilitate implementation of additional
measures if.standards change in the future or if contingency plans must be implemented.
7.
Comment
The commentor believes that the creation of a 1/2-mile buffer will allow the spread of
low-level contamination.
Response
EPA agrees that creation of a 1/2-mile "buffer zone", as proposed by Denver and WMC/
CWM, without the treatment and containment components of the selected sitewide
remedy, would allow offsite migration of contaminants to occur prior to initiation of
active measures to address the contamination problems.
On the other hand, EPA's selected sitewide remedy is designed to prevent offsite
contaminant migration and will not allow the spread of low-level contamination. The
selected remedy does not rely on offsite land acquisition and does not place primary
reliance on other offsite institutional controls to accomplish its objectives. While the
selected remedy is not dependent on offsite institutional controls as a primary element,
off site land use restrictions will provide an additional measure of protection and would
allow for contingency plans to be implemented should they become necessary.
Performance standards will not be exceeded beyond the ground-water compliance
boundary .
See responses to Comments 4, 5, and 6 for additional information. Also see responses to
Comments 2 and 5 through 11 under Denver and WMC/CWM.
8.
Comment
The commentor believes that the extraction component of the gas extraction system is
significant, and that the focus of OU3 should not be placed strictly on the control of gas
but also on the extraction of contaminants and removal of wastes through the gas
extraction system. By adding Stage 3 now, the commentor feels that for an additional
5 percent increase in the cost of sitewide remedy there would be a significant increase in
the annual volume of contaminants removed at the Lowry Site. The commentor believes
this is a good return on a relatively small increase in cleanup costs.
Response
For the selected remedy, Stage 3 is considered to be a contingency measure. EPA agrees
that Stage 3 (interior well network) gas extraction would remove more volatile organic
compounds (VOCs). However, at this time, it is not considered necessary for achieving
the performance standards. Stage 3 will be implemented if the perimeter gas extraction
system (Stage 2) does not meet the performance standards.
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BPA's overall objectives for Operable Unit 3 (landfIll gas) are to:
.
Prevent offsite migration of landfill gas; and
.
Protect human health and the environment from inhalation of landfill gas
and explosion hazards;
The selected remedy will achieve these objectives because it contains, collects, and treats
a significant amount of landfill gas. Also, the selected sitewide remedy is consistent with
EPA's Guidancefor Conducting Remedial Investigations/Feasibility Studies for CERCLA
Municipal Landfill Sites.
9.
Comment
The commentor supports the implementation of contaminant removal activities through the
removal of drums and contaminated soil in the former tire pile area.
Response
EP A acknowledges the support for the removal, treatment, and disposal of drums, drum
contents, and contaminated soils.
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14.2.4
Response to Written Comments
Wilbur Young, November 5, 1993 Letter
1.
Comment
The commentor asked whether reverse osmosis technology could be used as a treatment
technology at the Lowry Site, and if it might be less expensive.
Response
Reverse osmosis has been used in many applications for removing contaminants from
liquids, including ground water and industrial wastes. In general, reverse osmosis is
most effective for removing inorganic materials including metals, and least effective for
removing organic contaminants such as pesticides and industrial chemicals. In fact, there
are some organic chemicals that are capable of destroying reverse osmosis membranes.
It is for this reason that reverse osmosis was not chosen as a possible cleanup alternative
for the Lowry Site. In addition to the incompatibility of organic chemicals with
membrane material, reverse osmosis is subject to two additional disadvantages. First,
capital and operating costs are typically higher for reverse osmosis systems than for other
technologies. Second, reverse osmosis produces a leftover or "dirty water" stream that
must be properly disposed of. This stream contains all of the contaminants that do not
pass through the membrane and will be 25 to 50 percent of the original untreated volume.
Reverse osmosis does not result in a resin or other solid waste that may be disposed of or
processed for reclaiming.
2.
Comment
The commentor believes the general health of society would improve and industry would
benefit from cleaning up waterways.
Response
The selected sitewide remedy, which includes the Surface Water Removal Action, will
be protective of human health and the environment. All aspects of the sitewide remedy
will be monitored for effectiveness to ensure that cleanup standards are met.
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14.2.5
Response to Written Comments
City of Aurora
1.
Comment
The commentor endorses EPA's Proposed Plan for OUs 2, 3, 4, and 5 and accepts the
need for a containment-based remedy. The commentor supports the proposal to
concurrently install Stages 1 and 2 of the gas collection system, and endorses the plan to
excavate the buried drums, unsaturated waste pits, and contaminated soils in the former
tire pile area. The commentor feels that these aspects of the sitewide remedy are a
reasonable attempt to address long term risk by reducing the source of contamination.
The commentor is opposed to additional municipal solid waste being placed over the
former disposal areas in Section 6. Finally 1 the commentor is in favor of retaining for
continued use, any monitoring wells that may have future utility.
Response
EP A acknowledges the commentor's support of the selected remedies for landfill solids
and gas. EPA and CDH agree that additional municipal solid waste should not be added
to the former landfill mass. A more complete discussion of the proposal by Denver and
WMC/CWM and EPA's analysis may be found in the response to Comments 12 and 33
for Denver and WMC/CWM.
EP A also agrees that many of the monitoring wells may have future utility and may be
necessary to monitor the effectiveness of the sitewide remedy. These wells will not be
abandoned without a detailed evaluation of their potential use.
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14.2.6
Response to Written Comments
. City and County of Denver (Denver)
Waste Management of Colorado, Inc. (WMC)
Chemical Waste Management, Inc. (CWM)
The following comments were offered in relation to the Proposed Plan for Operable Units
(ODs) 2&3 and 4&5. EPA has taken into consideration that the comments may pertain
equally or in greater degree to the selected sitewide remedy or to the Proposed Plan for
ODs 1&6, although the comments were not specifically offered in connection with the
Proposed Plan for OUs 1&6.
On- and OfTsite Land Use and Access Controls
1.
Comment
The commentors asserted that the comments represent the collective views of over 140
generator, transporter, operator, and owner potentially responsible parties (PRPs) at the
Lowry Site.
Response
Due to the lack of documentation regarding the private settlements between PRPs, EP A is
unable to verify the accuracy of this statement. Nevertheless, EP A has given the
comments due consideration.
2.
Comment
The commentors stated that through or on behalf of the Lowry Landfill Superfunil
Trusts,l the commentors are prepared to acquire property anil water rights su"ounding
Section 6 of the Lowry Site, to at least 1/2 mile of the Lowry Site, and to then place
permanent land and ground-water use and access controls on these properties in order to
augment the protectiveness of the remedy. (Also refer to similar comments submitted by
the commentors, as documented in the summary of oral comments submitted by the
commentors during a meeting with EPA, held on October 22, 1993,' and oral comments
by the same commentors, as presented in the Transcript of the Public Meeting on
OUs 2&3 and 4&5, held on September 21, 1993.)
In the ojJsite areas, the commentors proposed controls that would restrict grounil-water
use in the Dawson and Denver aquifers for remediation purposes only. Residential and
'EPA believes that these Trusts are privately established instruments holding funds generated through settlement of third party
contribution suits initiated by Denver and WMC/CWM against other potentially responsible parties at the Site. The tnlsts are not
controlled by, or connected in any way, with the Federal government, and EP A has no independent knowledge concerning the
provisions of the trust agreements.
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municipal uses of ground water from these aquifers, in these areas, would be prohibited.
Additionally, the commentors stated that their proposed controls would not prohibit
ground water use in offsite areas in the Arapahoe and Laramie-Fox Hills aquifers.
Response
First, as the commentors acknowledge, some institutional controls have already been
established for Section 6 of the Lowry Site. These include Executive Order No. 97,
issued by former Denver Mayor Federico Pena. Executive Order No. 97 places certain
restrictions on development of the property, use of the ground water and surface water
onsite, and excavation or well drilling onsite.
The selected sitewide remedy shall include, at a minimum, those controls contained in
Executive Order No. 97. The selected sitewide remedy includes institutional controls to
prohibit future land use developments that would allow unacceptable human exposure to
landfill solids, gas, or ground water. At a minimum, the institutional controls include a
prohibition on land use that would damage the landfill cap and a prohibition against
installation of ground-water supply wells on the Lowry Site or in the immediate vicinity
of the Lowry Site. These institutional controls will be effective indefinitely.
Institutional controls required by the selected sitewide remedy are at least as broad and as
stringent as those established by Executive Order No. 97. EP A agrees with the
commentor that such onsite institutional controls must be adopted in the form of either
restrictive covenants or restrictive easements, which would be duly recorded instruments
attached to or included in the chain of title for the Sections 6 and 31 parcels presently
owned by Denver. These institutional controls would run with the land.
EP A, as evidenced by the selected sitewide remedy, also agrees with the com mentors that
such restrictive covenants or easements will be made enforceable by EP A or a neutral
party other than EPA. EPA, in consultation with the Colorado Department of Health
(CDH), will make the necessary determinations as to which land use and access controls
are appropriate.
EPA is adopting the commentors' proposal that land use and access control measures be
instituted in the areas immediately surrounding the Lowry Site. EP A agrees that the
selected sitewide remedy should contain offsite institutional controls to enhance the
protectiveness of the remedy, to allow expeditious and effective actions should
contingency plans be invoked or risk-based performance standards change, and to ensure
continued effectiveness of onsite controls. The size of the area to be addressed by the
offsite controls should be based on the expected area needed to meet these criteria.
EP A agrees with the com mentors that controls on construction of new residences
immediately adjacent to the Lowry Site, restrictions on access to areas adjacent to the
Lowry Site, and limitations on ground-water well construction and operation near the
Lowry Site are appropriate types of controls. In addition, it is clear that the likelihood of
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such controls being included in the chain of title would be enhanced if the land is owned
by parties, such as Denver and WMC/CWM, willing to impose the suggested restrictions.
3.
Comment
The commentors stated that they fully support the prefe"ed alternatives presented in the
Proposed Plan for the soils, swface water, and sediments OUs at the Lowry Site, but
indicated that this endorsement was conditioned on EPA's adoption of the commentors'
proposal to institute and rely on on- and ojfsite land use and access controls.
Response
EPA acknowledges the conditional support for its preferred alternative(s) for OUs 4&5.
As the commentors point out, the selected remedy includes active response measures to
separate clean surface water from potentially contaminated ground water and to collect
and treat contaminated ground water prior to its leaving the Lowry Site. The selected
remedy also includes as a minimal level the onsite institutional (land use and access)
controls described by the commentors, as well as offsite controls.
4.
Comment
The commentors indicated they believed that EPA's prefe"ed alternatives for OUs 2&3
ignore the studies and engineering evaluations done at the Lowry Site during the
Remedial Investigation/Feasibility Studies (RI/FSs). The commentors recommend that
EPA re-evaluate its determination of the prefe"ed alternative for OUs 2&3 and select tYre
remedial actions recommended by Denver and WMC/~ in the FSfor OUs 2&3.
Response
EPA recognizes that, based on the information presented in the RI/FSs for OUs 2&3,
Denver and WMC/CWM recommended different remedial alternatives in the FS than
those identified by EPA as the preferred alternatives in the Proposed Plan. However,
EP A carefully evaluated the information in the RI/FSs in identifying the preferred
alternatives for OUs 2&3 and fully evaluated the proposed remedies recommended by
Denver and WMC/CWM in the FS for those OUs. EPA has determined that its selected
remedies for these OU s represent the best balance of the nine evaluation criteria and are
more protective, in both the short and long term, of human health and the environment.
5.
Comment
The commentors propose that EP A rely on the land use controls proposed by Denver in
the draft Declaratory Statement of Covenants running with the land submitted with
Theresa Donahue's January 21, 1993 letter to Mr. Robert Duprey. Those proposed
controls would apply to Sections 6 (l'ownship 5 South, Range 65 West) and 31 (I'ownship
4 South, Range 65 West) that are part of the Lowry Site. The commentors proposed that
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either the State, EPA, or an independent Colorado non-profit organization be authorized
to enforce such covenants.
Response
EPA agrees that controls such as the covenants that run with the land, as proposed in
Denver's January 21, 1993 letter, should be adopted for the Lowry Site. The selected
sitewide remedy incorporates such controls as a minimum level of control for land and
ground-water use and on site excavation activities. However, EPA believes that the draft
covenants, as presented in Denver's January 21, 1993, letter, must be more definitive
concerning the restrictions on further landfIlling at the Lowry Site. The covenants must
be consistent with the selected sitewide remedy and must not allow additional disposal of
solid waste in the former landfill area, but also in disallowing other incompatible uses or
activities.
The covenants must permit additional ground-water well installation and operation, as
may be necessary, to monitor and remediate the aquifers beneath the Lowry Site.
However, the covenants must also provide restrictions on such wells for purposes related
to human or other uses. Finally, while EPA has not determined the appropriate
enforcement mechanism for such covenants, the selected sitewide remedy provides that
proper and adequate enforcement of such covenants must be assured. EPA, in
consultation with the State, will determine whether the instrument, in this instance the
covenants that run with the land, effectively provides for the controls included in the
selected sitewide remedy.
6.
Comment
The commentors 11lIlke several arguments in support of their proposal that the sitewide
remedy should include the above-described offsite land use restrictions. First, the
commentors assen that "although EPA guidance uniformLy indicates that residential use
scenarios are inappropriate, " EPA has identified the residential development scenario as
the basis for the primary site risks both on- and ojfsite. The commentors maintain that
their proposed controls will address that risk by controlling and limiting land development
on- and ojfsite and by assuring that development inconsistent with the selected sitewide
remedy does not occur. The commentors propose that the land will be maintained as
"open space" through the deed restrictions and covenants that run with the land.
Response
EP A disagrees with the commentors regarding the use of the residential development
scenario in assessing risk at the Lowry Site. The baseline risk assessment is not the
proper place to take institutional controls into account (55 FR 55 8710). EPA guidance
entitled Risk Assessment Guidance for Supeifund, Volume I Human Health Evaluation
Manual (pan A), Interim Final provides that a residential use scenario be employed in
the risk assessment process when available information suggests that future residential
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land use seems possible. In the case of the Lowry Site, ground water in the area is
currently used, and is expected to be used in the future, as a source of drinking water.
Furthermore, the Lowry Site is currently located near residential areas. Consequently,
future residential land use is a reasonable possibility.
Moreover, EP A has identified other risks at the site upon which remedial action is based.
Thus, EP A's selection of remedial action at the Lowry Site is not based solely on the
residential use scenario, but on a variety of risks identified at the Lowry Site.
The commentors proposal runs counter to EP A's procedures for assessing risk at a
Superfund site. As provided in EPA guidance and the NCP (55 FR 8709), one specific
objective of the risk assessment is to provide an analysis of baseline risk (Le., the risks
that exist if no remediation or institutional controls are applied to a site). In other words,
a baseline risk assessment is to be performed as if no institutional controls exist in the on-
or offsite areas. The com mentors ' proposal would require that EP A consider the
existence of institutional controls prior to, and as a presumption for, development of the
baseline risk assessment. EP A has determined that the procedures set forth in the NCP
and in EP A guidance produce the most reliable estimates of baseline risks at a site.
In essence, the com mentors ' proposal would require that EP A base its risk assessment on
institutional measures that are not yet in existence and were not in existence at the time
the risk assessment was performed. The approach suggested requires that EP A revise its
definition of baseline risks which is intended to represent the risks at a site in the absence
of any controls or active remedial measures. Such an approach does not provide a
framework to accurately assess site risks because it requires that EPA speculate on the
breadth and stringency of the proposed controls and project their effectiveness.
Finally, while the selected sitewide remedy imposes a complete prohibition on residential
development at the Lowry Site, EP A does not believe that its selected sitewide remedy
would necessarily require the offsite areas to be used as open space and that it is
premature to make such a determination. The remedy requires that offsite controls be
established to allow the unimpeded implementation of contingency plans should they
become necessary and to ensure the integrity and effectiveness of engineering controls.
Although EP A considers community acceptance in selecting a remedy, EP A received no
other comments urging that the areas surrounding the Lowry Site be maintained as open
space.
7.
Comment
The commentors state that the proposed restrictions will control and limit construction
and use of ground-water wells on- and offsite. The commentors also state that the
proposed restrictions will allow for monitoring at offsite locations. The commentors
further suggest that the proposed offsite restrictions will allow, as necessary, the
construction of containment measures.
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Response
EPA does agree that offsite ground-water well construction and extraction, particularly
high capacity wells, must be prohibited to the extent these wells interfere with or
diminish the protectiveness or effectiveness of the selected sitewide remedy. EP A also
agrees that it would be desirable to ensure in perpetuity that no wells will be constructed,
close to the Lowry Site, in aquifers that could potentially affect the movement of
contaminants off site, or adversely affect the engineered components of the selected
sitewide remedy. However, EP A does not agree that institutional controls such as those
proposed by the commentors are the only means to accomplish these goals in offsite
areas.
EP A does not believe that direct and blanket prohibitions on offsite ground-water wells
must be incorporated in the selected sitewide remedy at the present time. EP A has not
made a determination that all offsite well construction will necessarily affect the
movement of contaminants off site or adversely affect the engineered components of the
selected sitewide remedy. Based on present information on the potential effects of such
wells, EP A believes that this determination is best made on a case-by-case basis as
applications for such wells are made.
EPA disagrees that there is presently very little evidence that contaminants at the Lowry
Site could move offsite. In fact, recent monitoring data has shown evidence of
contaminants in ground-water wells at the western and southern boundaries of the Lowry
Site. EPA expects that such contamination, if confmned, will be fully addressed by
installation of the barrier wall and collection systems at the western and southern
perimeters of the Lowry Site.
Nevertheless, the presence of detectable contamination in these areas underscores the
need for engineered containment structures and systems in those areas. EP A has included
such containment systems in the selected sitewide remedy. Thus, EPA does not agree
that imposing institutional controls that merely prohibit future ground-water extraction is
the most prudent way to address the contamination presently detected at the landfill
perimeter.
The selected sitewide remedy includes monitoring of the containment systems to ensure
the sitewide remedy is effective. EP A agrees with the com mentors that monitoring in
offsite locations may be necessary in the future to verify that contaminants are not
moving offsite, to ensure the effectiveness of the barrier wall containment systems, or to
monitor actual offsite contaminant migration in case it does occur. However, EP A
disagrees that ownership by Denver and WMCICWM is necessary to implement
monitoring activities.
Finally, EP A agrees that offsite institutional controls are necessary at this time because
they would allow for future construction of additional containment systems. EP A's
selected sitewide remedy includes engineered containment components, such as the
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barrier walls at the south, west, and north perimeters of the Lowry Site, the cap, and the
ground water pump and treatment system. The selected sitewide remedy also includes
contingency measures that would address the failure of constructed barrier walls and
other containment features and any resulting offsite movement of contamination. Even
though such failure is not expected to occur, EP A would consider the need to locate
additional containment structures and systems in offsite areas. Offsite institutional
controls will facilitate and protect these aspects of the selected remedy. EP A does not
favor a remedy that would include the acquisition of land surrounding the Lowry Site for
the purpose of constructing containment structures farther out from the present extent of
the Lowry Site.
8.
Comment
The commentors state that the proposed restrictions will control and limit access to the
Lowry Site and adjacent areas.
Response
EP A agrees with, and the selected sitewide remedy includes, restrictions on access to
on site areas. The selected sitewide remedy does not include access restrictions to off site
areas. EP A does not believe controls on access to offsite areas is necessary at this time
to ensure protectiveness of the remedy. However, such controls may become necessary
if additional containment or monitoring systems are constructed in offsite areas due to
implementation of contingency plans that are part of the selected sitewide remedy, or in
the case of remedy failure.
9.
Comment
The commentors state that while appropriate zoning and well construction and land use
restrictions are possible with the cooperation 0/ local governments that have jurisdiction,
cooperative efforts have not borne fruit to date. The commentors recommend that land
and water right acquisition are the only reliable means 0/ ensuring that only compatible
uses are made 0/ land adjacent to the Lowry Site.
Response
EPA disagrees that the only reliable means of ensuring compatible offsite land use is
through the commentors' purchase of the land. First, no determination of what uses are
compatible has yet been made, nor has the selected sitewide remedy, including its
engineered active components, yet been constructed.
EP A agrees in general that some forms of institutional controls, land ownership and water
rights acquisition can enhance the reliability of institutional controls. However, as
discussed above, land ownership is not essential for adequate implementation of necessary
controls. Further, because of the inherent unreliability and impermanence of all
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institutional controls in comparison to engineered and/or active treatment remedial
actions, reliance on offsite institutional controls as a major remedial component is not
consistent with EP A's remedy selection requirements. EP A disagrees with the
com mentors that purchase of surrounding land and imposition of the suggested controls
will "eliminateh future risks. EPA's selected sitewide remedy places more emphasis
overall on active remedial measures. EP A believes that this approach is the best means
to manage and eliminate unacceptable risks posed by the Lowry Site. Offsite controls are
only necessary to support the integrity of the remedy by ensuring that onsite engineering
controlsremain effective; such controls are also required to effectively implement future
monitoring systems and to allow the expeditious implementation of contingency plans.
EPA does not believe that voluntary cooperative efforts to secure desirable land use
restrictions have been exhausted. The efforts of the Joint Southeast Area Planning
Initiative are ongoing. It is EP A's understanding that local governments with jurisdiction
over the areas adjacent to the Lowry Site have the same mandate as does Denver to
protect the health and welfare of their citizens. EPA expects that the presence of a
Superfund site, and the inherent risks presented by the contamination at the Lowry Site,
as well as the remedial measures that are and will be implemented, will be considered by
such local governments in future zoning and planning decisions. EP A believes that the
local governments share the concern that the Lowry Site remain safe.
10.
Comment
The commentors state that they believe their proposed remedy, including on- and offiite
ground-water, land use, and access controls, combined with the active aspects of the
remedial alternatives recommended by Denver and WMC/cm\1 in the FSfor OUs 2&3,
provide a remedy that is a better balance of the nine CERCLA evaluation criteria, and
specifically, is more protective than, the preferred alternatives as presented in the
Proposed Plans for all of the OUs.
Response
EP A disagrees that the suggested onsite and additional offsite land use and access controls
in combination with the response action alternatives recommended by Denver and WMC/
CWM in the FS for OUs 2&3 would represent a better balance of the nine CERCLA
remedy selection criteria, or that such a combination would be more protective than the
remedy selected by EP A. The Proposed Plan for OU s 2&3 and 4&5 highlights the
comparative analysis of remedial alternatives presented in the FS for OUs 2&3. The
active remedial measures included in the selected remedy, such as the barrier walls,
drums and contaminated soils removal, and gas collection/treatment make the selected
remedy more protective and more able to meet ARARs than the alternative recommended
by Denver and WMC/CWM in the FS.
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11.
Comment
The commentors propose that offsite land use and access controls be instituted in addition
to those presented by EPA in its preferred alternative for Section 6 at the Lowry Site, and
not in lieu of active response measures.
Response
EP A agrees that institutional controls should not be selected as a remedial component in
lieu of active response measures (55 FR 8846). In addition however, EPA believes that
the commentors' proposed remedy does in fact significantly reduce the active engineering
response measures from those included in EP A's selected sitewide remedy.
EP A can not determine at this time whether the long-term risks to human health would be
reduced to any degree if the commentors' proposed remedy were implemented and
believes that they could actually increase. EP A believes that the approach suggested by
the commentors, that is, reliance on institutional controls and the existence of a
monitoring or buffer zone, could ultimately lead to a situation similar to that existing
presently at the site (with potential residential development immediately adjacent to the
Lowry Site), but with a greatly expanded area of contamination.
Also, the remedy proposed by the com mentors has less assurance of meeting ARARs than
EPA's selected sitewide remedy, in particular for offsite areas. The selected sitewide
remedy includes barrier walls constructed at the waste management area boundary.
These barrier walls are designed and intended to prevent any off site migration of
contaminants. Any "breakthrough" will be immediately addressed by the contingency
measures included in the selected sitewide remedy. ARARs for the surrounding ground
water will thus be achieved. In the com mentors ' proposed remedy, action to install
barrier walls will be delayed until after "breakthrough" to offsite areas has occurred. If
barrier walls are constructed in the surrounding land and not at the waste management
area boundary, ARARs will be exceeded in those areas. ARARs must be met at all areas
outside the waste management area boundary when waste is left in place (55 FR 8753).
Detailed Comments on the Proposed Plan
12.
Comment
The commentors stated that Section 6 is not closed to municipal solid waste disposal.
Response
EP A and CDH disagree that the landfill in Section 6 is not closed. In accordance with
the Regulations Pertaining to Solid Waste Disposal Sites and Facilities (6CCRlOO7-2) and
40 CPR Part 258-Criteria for Municipal Solid Waste Landfills, the Solid Waste
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Section of the Hazardous Materials and Waste Management Division, Colorado
Department of Health, considers the former solid waste management unit in Section 6 to
be closed to municipal solid waste disposal.
Furthermore, adding waste to a Superfund site contradicts EPA's preference for a
reduction in waste volume. The addition of a significant quantity of municipal solid
waste to the existing landfill mass would also inhibit implementation of remedial activities
that might be deemed necessary in the future.
13.
Comment
The commentors stated that the dates of operation, provided in the OUs 2, 3, 4, and 5
Proposed Plan, for the barrier wall and the Ground Water Treatment Plant are incorrect.
The commentors noted that the barrier wall has been in operation since June 1984 and
that the Ground Water Treatment Plant has operated since October 1984.
Response
Information available to EP A suggests that the barrier wall was completed in the summer
of 1984. EPA disagrees that the treatment plant began operations in October 1984.
Based on the existing record, it is EP A's determination that the first interim remedial
measure (combined operation of both the barrier wall and treatment plant) began in 1985.
14.
Comment
The commentors stated that to be consistent with the No Further Action alternatives for
the soils, surface water, and sediments operable units (OUs 4&5), the No Action and No
Further Action alternatives for landfill solids and gas, as well as alternatives 3 and 7 for
landfill solids, should also have a "high level of compliance" with the short-term
effectiveness criterion.
Response
The com mentors are correct in noting that the No Action and No Further Action
alternatives for the landfill solids and gas operable units (OUs 2&3) should be identified
as having a high level of compliance with the short-term effectiveness criterion.
EPA disagrees that Landfill Solids (OU2) Alternatives 3 and 7 would have a high level of
compliance with the short-term effectiveness criterion. Landfill Solids Alternative 3
(Clay Cap) and Alternative 7 (Landfill Mass Regrading) would not have a high level of
compliance with the short-term effectiveness criterion for the following reasons. Both
alternatives involve disturbance of soils, which could precipitate impacts on workers or
pose risks to the community, during remedial action implementation. For example,
Alternative 3 includes placement of a clay cap over portions of the former tire pile area,
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and Alternative 7 includes removing the top layers of the existing landf1l1 mass cover and
regrading additional municipal solid waste on top of the landfill mass.
15.
Comment
The commentors noted that the description for the preferred alternative for OUs 1&6
should be consistent throughout the Proposed Plan for OUs 2&3 and 4&5.
Response
EP A agrees that the description of this alternative should be consistent throughout the
Proposed Plan for au s 2&3 and 4&5. The selected sitewide remedy includes
underground barrier walls and collection systems, and an upgradient containment,
collection, and diversion system.
16.
Comment
The commentors stated that there is no evidence that an upgraded ground-water treatment
facility will be necessary.
Response
EPA does not agree with the commentors' statement. The OUs 1&6 Feasibility Study
(FS) concluded that a second treatment plant or a modification to the existing ground-
water treatment plant may be necessary to treat highly contaminated ground water
collected at the base of the northern slope of the landfill mass. The sitewide remedy
must meet all performance standards and ARARs. During remedial design, the existing
treatment plant will be evaluated to determine whether or not it is capable of treating:
higher volumes of contaminated ground water; higher contaminant concentrations in the
ground water; contaminants present at the site but not currently found within the
treatment plant influent. If it is determined that the existing plant is not able to meet
performance standards, the plant will be upgraded accordingly.
17.
Comment
The commentors asked for an explanation of the difference between the costs in the
OUs 1&6 Proposed Plan and those summarized for OUs 1 &6 in the Proposed Plan for
OUs 2&3 and 4&5. In addition, the commentors asked EPA to provide costs for the
preferred alternatives to explain the differences between those alternatives and the
recommended FS alternatives.
Response
The costs for the OUs 1&6 alternatives in the OUs 1&6 Proposed Plan included costs that
had already been incurred; specifically the capital costs associated with the SWRA. For
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the OUs 2&3 and 4&5 Proposed Plan, EPA chose to exclude the capital costs previously
inCUlTed through implementation of the SWRA. Where components of the different OU
alternatives overlapped, EP A removed the duplicated cost estimates. This included, for
example, deletion of the SWRA operating and maintenance (O&M) costs from the cost
estimate for the prefelTed alternative for OUs 1&6. O&M costs for the SWRA are
accounted for in the cost estimate for the prefelTed alternative for OUs 4&5. Also, the
costs associated with the OUs 1&6 prefelTed alternative, as presented in the OUs 2&3
and 4&5 Proposed Plan, include estimates for underground barrier walls and associated
well extraction systems.
The cost estimates for each pair of OUs (1&6, 2&3, and 4&5) were developed using
slightly different cost-estimating methodologies. This is due to the fact that a separate
feasibility study was prepared for each set of OUs. Each study estimated indirect costs
by assuming different percentages of direct costs.
Indirect capital costs include items that are incidental to direct capital costs such as
engineering and design, legal fees, permitting requirements, EPA review and oversight,
and a contingency for unexpected costs. Indirect O&M costs represent the estimated
costs for administrating the O&M work and a contingency for unexpected costs. For the
prefelTed alternatives, indirect capital costs ranged from 70 to 80 percent of direct capital
costs, while O&M indirect costs ranged from 17 to 30 percent of O&M direct costs. To
maintain consistency, EP A used the same percentages (80 percent for capital costs and
30 percent for O&M costs) for each OU.
18.
Comment
The commenlors are concerned that the use of specific numbers in the Proposed Plan will
constrain the Remedial Design effort.
Response
EPA disagrees that the Remedial Design will be constrained. EPA's-focus is to ensure
that the performance standards, specified in the selected remedy, are achieved.
The Proposed Plan for OU s 2&3 and 4&5 provides estimates of such quantities as
volume of material to be excavated and number of wells to be installed. Approximation
is appropriate at this stage of the process and is necessary for cost estimating purposes.
EP A acknowledges that it may be necessary to review these estimates during the remedial
design. However, both the excavation and well-installation components are included as
key components of the selected remedy and both activities must be implemented such that
the performance standards specified in the selected remedy are achieved and maintained.
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19.
Comment
The commenJors stated that the Proposed Plan fails to incorporate existing remedy
elements and those proposed for OUs 1&6. As an example, the commentors suggested
that the existing ground-water treatment plant does not appear to have been factored inJO
the prefe"ed alternative for landfill solids. The commenJors also stated that the costs of
certain IRMs do not appear to be factored into the selected alternatives.
Response
EP A disagrees that the Proposed Plan fails to incorporate existing or proposed remedy
elements. The Proposed Plan for OUs 2&3 and 4&5 incorporates both existing remedial
elements and the preferred alternative for OUs 1&6. In fact, the existing interim
remedial measures (IRMs) and the preferred alternative for OUs 1&6 are an integral part
of the selected sitewide remedy and are discussed in the Proposed Plan for OU s 2&3 and
4&5.
The benefits and treatment aspects of existing IRMs and the preferred alternative for
OUs 1&6 were not specifically mentioned in the separate analyses of each alternative for
each operable unit. However, the remedial benefits, treatment, and costs of existing
IRMs and the preferred alternative for OUs 1&6 were factored into the sitewide remedy
discussion and comparative analysis.
The existing ground-water treatment plant and barrier wall address contaminated ground
water that is flowing from the landfill mass and the former tire pile area. While the
treatment plant and barrier wall do not provide for source reduction, the preferred
alternative for landfill solids does. The preference for removal of accessible hot spots is
consistent with EP A's guidance Conducting Remedial Investigations/Feasibility Studies for
CERCLA Municipal Landfill Sites.
20.
Comment
The commenJors stated that excavation in the former tire pile area could create short-term
exposure to workers as well as become a risk to the public during offsite transportation.
Response
The Proposed Plan for OU s 2&3 and 4&5 acknowledges that excavation in the fonner
tire pile area may create short-term exposure risks for workers. EPA recognizes that
offsite transport of wastes has the potential to create short-term exposure risks for the
general public.
The Feasibility Study (FS) for OU s 2&3 notes that it is anticipated that an increase in
organic emissions, and possibly inorganic emissions, would be incurred as a result of
excavation of the buried drums and contaminated soils. Emissions would be controlled
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using appropriate dust suppression methods that may include the use of water, foam, or
cover materials such as PVC sheeting. The FS also evaluated the worst-case potential
risks from increases of VOCs, as a result of excavation activities in the former tire pile
area. Modelling results indicated that if a worker were continually exposed without
protective equipment, the lifetime cancer risk would be 2 X 10-5. This calculation is
based on conservative assumptions. Even with these assumptions, the potential risk is
within EPA's acceptable range of 1 x lQ4 to 1 x 1~. Using more realistic assumptions
(such as the use of protective equipment), the risks would be much lower than lxl
-------
the average, about five gallons of liquid may be present in each of the estimated 257
liquid-filled drums. This would yield a tota1liquid volume of no less than 1,300 gallons
of waste. Estimates show that a significant amount of source material may be removed
through limited excavation of the hot spots in the former tire pile area.
The contaminant sources discussed in the Proposed Plan for OUs 2&3 and 4&5 include
contaminated solids and liquid-filled drums that provide a source of contamination to
other media such as ground water. The intent of the preferred alternative for OU2 is to
remove higher concentration contaminated solids that are accessible. The excavation will
include not only drums, but also contaminated soils and other material surrounding the
drums.
22.
Comment
The commentors stated that liquids leached from the former tire pile area will be captured
at the barrier wall and through the SWRA, indicating that additional measures will not be
necessary in the former tire pile area.
Response
EP A does not agree that additional measures will not be necessary in the former tire pile
area. The SWRA collection system and barrier wall intercept some of the contaminated
liquids which have migrated laterally from waste pits within the former tire pile area.
These liquids are treated at the existing ground-water treatment facility. It is undesirable
to allow perpetual seepage out of the waste pits in the former tire pile area. Elimination
of this source of contamination, through excavation, reduces the potential for additional
contamination of ground water. The excavation option has the following advantages:
.
It further reduces a principle source of risk to human health and the
environment;
.
It removes accessible hot spots;
.
It complements the source-control component (for the landfill mass) of
the preferred alternative for OU2; and
.
It complies with the statutory requirements of CERCLA.
23.
Comment
The commentors believe that the risks are minimal in the former tire pile area and claim
that the drums, soils, and waste pits are separated from the surface by an engineered
drainage system. The commentors also stated that land use and access controls would
eliminate public exposure to subsurface solids.
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Response
Contaminated solids in the former tire pile area, within the SWRA collection system
boundary, are separated from the surface by an engineered drainage system. The
remainder of the former tire pile area does not have an engineered drainage system.
Institutional controls such as access and land use restrictions will be implemented but
only to supplement, and not replace, such engineering controls as excavation of the
contaminated solids.
24.
Comment
The C017l1Tl£ntors are concerned that excavation of the former tire pile area will involve
the potential for ground-water recharge in disturbed areas.
Response
EP A believes that ground-water recharge can be prevented or limited through the
following means:
.
Excavation can be sequenced to minimize the open excavation areas;
.
Engineering controls (such as berms) can be used to divert ponded
water;
.
The time period that the excavation area is kept open can be limited;
and
.
Storm water that may accumulate in the excavation area can be removed
and treated onsite.
25.
Comment
It is the commentors' opinion that removal of the drums, soils, and waste pits in the
former tire pile area is not consistent with EPA guidance Presumptive Remedy for
CERCLA Municipal Landfill Sites, OSWER Directive 9355.D-49FS, September 1993. The
commentors identify four questions to be answered in evaluating the reasonableness of
excavation as a cleanup alternative. The first question is whether or not evidence exists
to indicate the presence and location of waste. The commentors stated that there is no
evidence of intact drums or perched waste.
Response
EP A disagrees that the removal of the drums, soils, and waste pits is not consistent with
EPA guidance. The proposed excavation, removal, treatment, and disposal of drums,
drum contents, contaminated soils, and contaminated debris fully complies with EPA's
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guidance entitled Presumptive Remedy for CERCLA Municipal Landfill Sites [OSWER
Directive 9355.0-49FS, September 1993]. This guidance indicates that the primary
response action objectives for municipal landfill sites should include preventing direct
contact with contaminated solids and minimizing contaminant infiltration to ground water.
The preferred alternative for OU2 fulfills this requirement and is based on a
determination that: evidence exists to indicate the presence and approximate location of
waste; the hot spot is known to be a principal threat waste; the waste is in a discrete,
accessible area of the site; and the hot spot is known to be large enough that its
remediation will reduce the threat posed by the overall site but small enough that it is
reasonable to consider removal.
EPA's first response addresses the commentors' belief that there is no evidence of intact
drums or perched waste. Sufficient evidence exists to indicate the presence and
approximate location of waste in the former tire pile area. This evidence includes: aerial
photographs; results from soil gas surveys, borings, and waste pit well points;
geophysical studies; test pits analyses; and visual observation of contaminated liquid seeps
in the former unnamed creek. Specifically, the Feasibility Study, Volume 2, Lowry
Landfill: Landfill Solids and Landfill Gas Operable Units (OUs 2&3), Rem£dial
Investigation and Feasibility Study, Arapalwe County, Colorado estimates that, at a
minimum, approximately 257 buried drums may contain liquids and that there may be, at
a minimum, 1,300 gallons of liquid waste in these drums. Thus, substantial evidence
exists that perched liquids are present in the former tire pile area.
26.
Comment
The second question posed by the commentors is whether or not the hot spot is known to
be a principal threat waste. The commentors stated that the wastes are not unique.
Response
The concept of a principal threat waste is to be applied on a site-specific basis when
characterizing source material. A Guide to Principal Threat and Low Level Threat
Wastes [OSWER Directive 9380.3-06FS, November 1991] defines source material as
material that includes or contains hazardous substances, pollutants or contaminants that
act as a reservoir for migration of contamination to ground water, or acts as a source for
direct exposure. Source materials may include drummed wastes, contaminated soil and
debris, or dense non-aqueous phase liquids (DNAPLs).
As established in the NCP [40 CFR 3oo.430(a)(I)(iii)], EPA expects, at a minimum, to:
1.
Use treatment to address the principal threats posed by a site, wherever
practicable. The EP A guidance document entitled A Guide to Principal
Threat and Low Level Threat Wastes [OSWER Directive 9380.3-06FS,
November 1991], states that principal threat wastes are those source
materials considered to be highly toxic or highly mobile that cannot be
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reliably contained or would present a significant risk to human health or
the environment should exposure occur.
2.
Use engineering controls, such as containment, for wastes that pose a
relatively low long-term threat or where treatment is impracticable.
3.
Use a combination of methods to achieve protection of human health and
the environment. Treatment of principal threats will be combined with
engineering controls and institutional controls for treatment residuals and
untreated waste.
The source materials discussed in the Proposed Plan for au s 2&3 and 4&5 include, at a
minimum, contaminated soil and debris and drummed waste that provide a continuous
source of contamination to the ground water. These source materials would present a
significant risk to human health or the environment if exposure were to occur and
comprise the hot spots identified in the former tire pile area at the Lowry Site. The hot
spots are principal threat wastes and are in a discrete, accessible area of the site.
For additional discussion concerning documented evidence of buried liquid-filled drums in
the former tire pile area, please see the response to Comment 21.
27.
Comment
The third question posed by the commentors is whether or not the waste is in a discrete
accessible part of the landfill. The commentors stated that the drums are not easily
accessible.
Response
EPA disagrees that the wastes are not easily accessible. The hot spots that are targeted
for excavation and treatment are located in an area that is physically separate from the
main body of the landfill mass. EP A guidance does in fact suggest that it would be
difficult to excavate and/or treat a landfill mass, but allows for circumstances in which
source materials are located in separate or discrete and accessible areas.
The contaminated material to be excavated and treated is located in a discrete, accessible
area, separate from the landfill mass. The waste is accessible through conventional
excavation and construction techniques. The proposed construction process is provided in
detail in Subsection 4.2.1.4 of the DUs 2&3 Feasibility Study. While many of the drums
to be recovered may be deteriorated and construction debris over the waste pits may add
some level of complexity to the excavation, neither of these issues are believed to be
significant, and both can be addressed through proven technology.
DENlOOlS3C7.WPS
14-41
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The com mentors may also refer to the response to Comment 21 for additional discussion
of a similar ~xcavation project conducted at the Denver-Arapahoe Chemical Waste
Processing Facility adjacent to the Lowry Site.
28.
Comment
The fourth question posed by the commentors is whether or not the hot spot is large
enough to reduce risk but small enough to consider removal. The commentors stated that
the area is not large enough to reduce the threat posed by the overall site.
Response
EPA disagrees that the area(s) to be excavated are not large enough. The preferred
alternative for OU2 is a combination of excavation in the former tire pile area and
containment of wastes within the landfill mass. These components of the sitewide
remedy would be implemented simultaneously.
In evaluating overall site risk reduction, EP A believes it is appropriate to separately
consider the containment portion (southern portion of the Lowry Site) and the non-
containment portion (northern portion including the former tire pile area of the Lowry
Site). In doing so, risks from principal threats within the main landfill mass are
effectively contained in the southern portion of the Lowry Site. Principal threats in the
former tire pile area would be significantly addressed through excavation. Excavation in
the former tire pile area is large enough to significantly reduce the majority of risk in the
former tire pile area and is small enough that it is reasonable and practical to consider.
29.
Comment
The commentors stated that the preferred alternative for landfill solids does not meet the
requirements of the NCP. The commentors also claimed that the prefe"ed alternative is
not cost effective and EPA's Proposed Plan did not evaluate long-term effectiveness,
treatment, and short-term effectiveness. Finally, the commentors stated that EPA's
Proposed Plan focused on ojJsite treatment, did not consider existing onsite treatment,
and short-term risks to onsite workers were hardly mentioned.
Response
The preferred alternative does meet the requirements of the NCP. EP A, in consultation
with CDH, performed a detailed analysis of all the alternatives, including Modified
Alternative 4 (Drum RemovallOffsite Disposal/North Face Cover). This analysis
consisted of two parts: an assessment of individual alternatives against each of the nine
evaluation criteria; and a comparative analysis that focused upon the relative performance
of each alternative against the nine criteria.
DENlOO153C7.WP5
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With regard to the preferred alternative and the requirements of the NCP, the results of
EPA's detailed analysis demonstrate that Modified Alternative 4 (Drum Removal/Offsite
Disposal/North Face Cover) offers: the greatest protection of human health and the
environment by removing contamination in the former tire pile area; the greatest long-
term effectiveness and permanence through removal of contaminated material; and the
greatest reduction of toxicity, mobility, and volume of contaminated solids through
treatment.
The analysis also affirmed that the preferred alternative: is comprised of proven
technologies; is implementable; complies with applicable or relevant and appropriate
requirements; is fully supported by the State of Colorado; and has a high degree of
acceptability to the community.
The com mentors are correct in noting that cost effectiveness is determined by evaluating
the following items: long-term effectiveness and permanence; reduction of toxicity,
mobility, or volume through treatment; and short-term effectiveness. Modified
Alternative 4 (Drum Removal/Offsite Disposal/North Face Cover) is cost effective for the
reasons discussed below.
EP A disagrees that it did not consider, or that it gave less than due consideration to, the
following criteria: long-term effectiveness; short-term effectiveness; and onsite
treatment. First, EPA considered that Modified Alternative 4 (Drum Removal/Offsite
Disposal/North Face Cover) provides long-term effectiveness and permanence through
removal of contaminated drums, debris, and soils from the former tire pile area. There
is a high degree of certainty that this alternative will prove successful and implementation
of this alternative eliminates the need to consider either the magnitude of residual risk
remaining from untreated waste or the adequacy and reliability of controls such as
containment systems to manage the untreated waste.
Second, EP A considered that Modified Alternative 4 (Drum Removal/Offsite Disposal/
North Face Cover) does in fact address treatment of drum contents and contaminated
soils. This alternative provides for a significant reduction in toxicity, mobility, and
volume of drum contents and contaminated soils through excavation and treatment at an
offsite facility. Treatment would include, at a minimum, incineration and ash
stabilization.
Third, the following potential short-term impacts of Modified Alternative 4 (Drum
Removal/Offsite Disposal/North Face Cover) were also evaluated: short-term risks that
might be posed to the community during implementation of the alternative; potential
impacts on workers during remedial action and the effectiveness and reliability of
protective measures; potential environmental impacts of the remedial action and the
effectiveness and reliability of mitigative measures during implementation; and time until
protection is achieved.
Excavation projects, similar in nature to the preferred alternative, have been successfully
and safely implemented both on site and offsite with minimal short-term risks. On site
DEN I OOIS3C7.WPS
14-43
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excavation of soils and potentially contaminated material was performed as part of the
construction of the Surface Water Removal Action collection system within Unnamed
Creek. Drum excavation and removal activities were also successfully completed in
Section 32, in connection with the corrective action at the Denver-Arapahoe Chemical
Waste Processing Facility.
Experience from these projects indicates that implementation of the preferred alternative
would pose minimal short-term risk to the community. Furthermore, the preferred
alternative can be implemented using effective and reliable protective measures for the
cleanup workers. Also, mitigative measures employed during the implementation of the
above-referenced excavation projects have proven to be effective in minimizing adverse
impacts to the environment during remedial action.
In responding to the commentors' suggestions that EPA only focused on offsite treatment
and that existing onsite treatment was not considered, the following points can be made.
First, of the seven alternatives evaluated for remediation of the landfill solids, two
alternatives involve no excavation, one alternative involves excavation and disposal either
on- or offsite, three alternatives involve excavation and offsite treatment and disposal,
and one alternative includes excavation and both on site and offsite treatment and disposal.
Second, regarding the commentors' suggestion that the existing ground-water collection
and treatment systems were not considered during the comparative evaluation of the
alternatives for the landfill solids, please see the responses to Comment 19 and Comment
22.
30.
Comment
The commentors are opposed to excavation in the former tire pile area for the following
reasons: ground water treatment is already in place; there is a potential risk to onsite
workers; long distance transport of excavated materials would be necessary; there would
be congressional disapproval for offsite transport; and excavation in the former tire pile
area does not meet the short-term effectiveness criteria.
Response
EPA acknowledges that a ground-water collection/treatment system is in place and is
designed to capture dissolved contaminants in the ground water. However, source
reduction through excavation in the former tire pile area will address a principal threat at
the Lowry Site (see the response to Comment 22). The potential risks to onsite workers
and associated with offsite disposal are discussed in Comments 19 and 20.
31.
Comment
The commentors believe that Modified Alternative 4 (Drum Removal/Ojfsite Disposal/
North Face Cover) is not cost-effective and is not eligible for selection as the remedy.
DENlOO153C7.WP5
14-44
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Response
Please see the response to Comment 29 and the Record of Decision for a discussion of
the cost-effectiveness of Modified Alternative 4 (Drum Removal/Offsite Disposal/North
Face Cover).
32.
Comment
The commentors noted that the Feasibility Study for OUs 2&3 contained an alternative
that included the following components: the placement of additional cover materials over
those areas of the former tire pile area that potentially contain drums and waste; and
permanent land use and access controls on the property. The commentors also provided
an analysis of this alternative within the context of the nine evaluation criteria.
Response
In preparing the Proposed Plan for ODs 2&3 and 4&5, EPA evaluated the alternative
cited by the commentors. The results of EPA's comparative analysis indicated that other
alternatives more fully complied with the nine evaluation criteria.
33.
Comment
The commentors stated that the existing cap on the fOrrnf!r landfill should be enhanced
and regraded using municipal solid waste.
Response
EP A disagrees that the existing cap needs to be enhanced by the means suggested by the
commentor. The com mentors ' proposed approach is part of Landfill Solids Alternative 7,
which was evaluated as part of the FS for ODs 2&3. EPA performed a comparative
analysis of this alternative in accordance with the nine evaluation criteria established in
the NCP. Justification for not selecting this alternative may be found in the Record of
Decision. The regulatory history of the Section 6 municipal solid waste (MSW) landfIll,
and its relationship to EPA's and CDH's analysis of Landfill Solids Alternative 7, is
discussed below.
CWM initially submitted a closure plan to CDH for the Section 6 MSW landfill in
November 1980. The Closure Plan was approved for the complete filling of Section 6
(from Quincy Avenue to Hampden Avenue) to a maximum fmal cover altitude of
5,862.5 feet. This plan was modified in 1985 to accommodate Superfund activities;
however, the modification only stopped the northward growth of the MSW landfill while
the fmal altitude remained the same. On August 3, 1990, WMC ceased MSW landfilling
in Section 6 and began to utilize the engineered MSW landfill that was constructed in
Section 31 of the Denver/Arapahoe Disposal Site (DADS) facility. WMC submitted the
Quality Assurance report for the final cover of the Section 6 MSW landfIll of the DADS
DENlOOlS3C7.WP5
14-45
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facility in 1992. The report stated that the fmal cover installed over the MSW landfill in
Section 6 me.t all minimum engineering requirements specified in the regulations under
which the Section 6 MSW landfill had operated.
EP A, in consultation with CDH, has determined that ARARs regarding the LandfIll
Solids Alternative include the requirements specified in the State of Colorado's
Regulations Pertaining to Solid Waste Disposal Sites and Facilities (6CCR1007-2) (SW A)
and the Federal regulations titled Solid Waste Disposal Facility Criteria (4OCFR Part 258)
(Subtitle D).
In addition, RCRA Subtitle D regulations, 40 CFR Part 258.2, define an existing
municipal solid waste landfill (MSWLF) unit to be a MSW landfill that received MSW as
of October 9, 1993. The Section 6 MSWLF unit did not receive MSW as of that date.
Thus the MSW landfIll in Section 6 is not an existing unit. All units not existing are
considered to be closed. Based on this determination, Landfill Solids Alternative 7 could
only attain ARARs if Alternative 7 could meet criteria specified in the SW A. Section 3
of the SW A requires that all new MSW units be constructed with engineering liners and
leachate collection systems on a stable sub-base. Consequently, EP A and CDH do not
believe that Alternative 7, as proposed, could meet these requirements. This conclusion
conflicts with the results of the initial ARARs evaluation, which was presented in the
Proposed Plan for OUs 2&3 and 4&5. As presented in the proposed plan, EPA and
CDH initially concluded that the Landfill Solids Alternative 7 would comply with
ARARs. However, based on the additional analysis presented above, Landfill Solids
Alternative 7 would not comply with ARARs.
The com mentors assert that the additional cover proposed for installation to the closed
MSW landfill in Section 6 will meet the new Subtitle D requirements by increasing the
slope of the final cover to a steeper grade. This type of approach to closed MSW
landfills is not within the intent of the State and Federal Subtitle D requirements.
EPA and CDH consider the solid waste management unit within Section 6 to be closed to
additional MSW disposal.
In addition, the placement of an additional 1.2 million cubic yards of MSW onto the
existing landfill mass would serve to further limit access in the event that, in the future, it
was determined that excavation was necessary.
34.
Comment
The commentors disagree with the simultaneous installation of the first tWo stages of the
gas collection system. The commentors also believe that the Proposed Plan for OUs 2&3
and 4&5 has been manipulated to improperly compare Modified Alternative 3 (Gas
Collection/Enclosed Flare) to Stage 1 of Alternative 3 (Gas Collection/Enclosed Flare).
DENlOOI53C7.WP5
14-46
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Response
EP A disagrees that the simultaneous installation of the first two stages of the gas
collection system is unjustified. The preferred alternative for landfill gas, Modified
Alternative 3 (Gas Collection/Enclosed Flare), includes a phased installation of gas
collection wells in the landfill mass. The first phase is a combined source reduction and
perimeter gas collection system (Stages 1 and 2 in the ODs 2&3 Feasibility Study).
Installing the perimeter gas collection component is warranted for the following reasons:
.
Shallow subsurface geologic uncertainties at the perimeter of the landfIll
mass indicate that targeting the few known areas of gas migration (as is
proposed under Stage 1) may not comprehensively address all pathways
for migration (monitoring points at some locations are as far as a 1/4
mile apart).
.
The cost difference in targeting a few areas (Stage 1-$8.4 million)
versus the entire perimeter (Stages 1 and 2-$9.2 million) is minimal
when compared to the increased level of protection.
.
By installing the perimeter gas collection system, there will be less
reliance on monitoring and significant removal and treatment of
contaminants.
.
The level of protectiveness achieved by combined Stages I and 2 is
higher than for Stage 1 only.
.
Perimeter gas collection systems have proven effective at other landfills
in Colorado.
Installing a full-perimeter gas collection system would not delay the start of remedial
action as implied by the commentors.
EPA does not agree that the Proposed Plan for ODs 2&3 and 4&5 improperly
manipulated the comparative analysis of Modified Alternative 3 (Gas Collection/Enclosed
Flare) and Stage 1 of Alternative 3 (Gas Collection/Enclosed Flare). EPA's analysis is
justified because the comparison between the two alternatives was made based on the
implementation of engineered technology without contingencies. EP A believes it has
fairly evaluated these two alternatives in the Record of Decision.
35.
Comment
The commentors believe that the specificity contained in the Proposed Plan for OUs 2&3
and 4&5 (i.e., the exact number 01 collection and monitoring wells) cannot be justified
and should be evalumed during the remedial design phase.
DENlOOI53C7.WPS
14-47
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Response
A detailed technical justification for the estimated number of collection and monitoring
wells identified in the alternatives may be found in the Feasibility Study for GUs 2&3.
As mentioned in the response to Comment 18, the Proposed Plan for GUs 2&3 and 4&5
must, for conceptual and cost estimating purposes, provide estimates of such quantities as
the number of wells to be installed. EPA aclrnowledges that it may be necessary to
review and revise these estimates during the remedial design. However, the specific
numbers must be sufficient to fully meet all performance standards identified in the
selected sitewide remedy.
Comparison of Remedies in the Proposed Plan
with those in the Feasibility Study in
Combination with Land Use and Access Controls
36.
Comment
The commentors summarize the analysis 01 alternatives, as presented in the Feasibility
Study for OUs 2&3 (Denver/WMC/CWM, April 1993), and supplement this analysis with
an additional discussion of possible onsite and ojfsite institutional controls.
Response
This comment serves as a summary of the set of specific comments received from the
commentors. Therefore, the reader is asked to review the Responsiveness Summary for
individual responses.
DENlOO153C7.WP5
14-48
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.....
~
~
Table 14-1
Chemical Concentration Data Summary Page 1 or5.
95th Percentile Upper Confidence Limit on the Geometric Mean of the Median Well Concentrations
(pgtl)
SbaIlow Ground-water Monitoring Ground-water Monitoring Ground-water Monitoring Deep Ground- Upgradieot Ground-
Wells Completed in Weathered Wells Completed in Wells Completed in water water Monitoring
Dawson and Waste Pit Llqnlds Well Weathered Dawson AquiFer Unweathered Dawson AquiFer Monitoring Wells Outside the
Chemical Name Point5 Within the Source Area Out5ide or the Source Area Outside or the Source Area Wells Source Area
I. I. I-Trichloroethane 250 120 4.3 15 4.3
1.1,2,2- Tetrachloroethane 31 NO NO NO NO
1.1,2- Trichloroethane 29 5.9 NO 2.6 NO
1,1-0ichloroethane 520 47 3.2 13 NO
1,1-0ichloroethylene 83 41 2.7 11 2.9
1,2,4-Trichlorobenzene 18 7.3 NO NO NO
1.2-0ichlorobenzcnc 18 NO NO NO NO
1.2-0ichloroethanc 590 13 4.3 NO NO
1,2-0ichloroethcne (total) 140 31 NO 3.5 NO
1,2-Dichloropropane 29 8.7 NO 2.6 NO
cis-I.3-0ichloropropenc 27 NO NO NO NO
trans-l,3-dichloropropene 26 NO NO NO NO
1.4-0ichlorobenzene 21 7.9 NO NO NO
2,3,7.8-TCOO (dioxin)' 0.00053 0.000020 0.000024 0.0002 NO
2,4,5-T 3.9 NO 0.27 NO NO
2,4,5-TP 5.3 NO NO NO NO
2.4,5-Trichlorophenol 90 NO NO NO NO
2,4.6-Trichlorophenol 24 NO NO NO NO
2,4-0 23 1.4 NO NO NO
2.4-0ichlorophenol 31 6.4 NO NO NO
2.4-0imethylphenol 80 7.1 NO NO NO
2.4-0initrophenol 220 NO NO NO NO
2-Butanone (MEK) 980 7.1 5.5 NO 6.1
2-Chloronaphthalene 18 NO NO NO NO
2-Chlorophenol 25 NO NO NO NO
2-Hexanone 45 9.8 5.1 NO NO
2-Methylnaphthalene 58 NO NO NO NO
OEN100153BO.WP5
-------
I-"
~
I
VI
o
Table 14-1
Chemical Conceotration Data Summary Page :z or 5
95th Perceotile Upper Confidence Limit on the Geometric Mean or the Median Well Conceotrations
(pgII)
Shallow Ground-water Monitoring Ground-water Monitoring Ground-water Monitoring Deep Ground- Upgradient Ground-
Wells Completed In Weathered Wells Completed In Wells Completed in water water Monitoring
Dawson and Waste Pit Liquids Well Weathered Dawson Aquifer Unweathered Dawson Aquifer Monitoring Wells Outsille the
Chemical Name Points Within the Source Area Outside or the Source Area Outside or the Source Area Wells Source Area
2-Methylphenol 54 6.6 NO NO NO
4,4'-000 0.19 NO NO NO NO
4,4'-00£ 0.17 NO NO NO NO
4,4'-00T 0.18 NO NO NO NO
4-Bromophenyl-phenylether NO 7.9 NO NO NO
4-Methyl-2-pentanone(MmK) 520 10 5.1 6.6 8.4
4-Methylphenol 140 7.1 NO NO NO
4-Nilroaniline NO 40 NO NO NO
Acenaphthene 17 7.3 NO NO NO
Acetone (2-propanone) 2,800 23 16 35 10
Aldicarn 4 NO NO NO NO
Aldicalb sulfoxide 3 0.71 NO NO NO
Alpha chlordane 0.28 NO NO NO NO
Alpha-BHC 0.10 NO NO NO NO
Aluminum 5,200 97 120 340 560
Aniline 94 NO NO NO NO
Anthracene 21 NO NO NO NO
Antimony 52 18 20 3.5 10
Arsenic 110 9.5 2.6 NO 15
Barium 620 53 44 87 48
Benzene 270 6.7 3.0 5.6 NO
Benzo(a)anthracene 17 NO NO NO NO
Benzo{g,h,i)perylene NO 7.9 NO NO NO
Benzoic acid 820 35 NO NO 41
Benzyl alcohol 53 NO NO NO NO
Beryllium 5 NO 0.97 1.7 1.3
bis(2-chloroethyl)ether 22 NO ND ND 7.1
-------
......
~
I
VI
......
Table 14-1
Chemical Concentration Data Summary Page 3 or 5
95th Percentile Upper Confidence Limit on the Geometric Mean or the Median Well Concentrations
(pall)
Shallow Ground-water Monitoring Ground-water Monitoring Ground-water Monitoring Deep Ground- Upgradieot Ground-
Wells Completed In Weathered Wells Completed In Wells Completed In water water Monitoring
Dawson and Waste Pit Liquids Well Weathered Dawson Aquirer Unweathered Dawson Aquifer Monitoring Wells Outside the
Chemical Name Points Within the Source Area Outside or the Source Area Outside or the Source Area Wells Source Area
bis(2-elhylhexyl)phlhalate 82 7.3 5.4 9.3 23
Boron 2,700 400 220 310 130
Bromodichloromelhane 22 5.1 ND ND ND
Bromoform 30 6.1 ND ND ND
Butylbenzylphthalate 25 ND ND ND ND
Cadmium 27 ND 2.2 ND 2.6
Carbaryl 5 ND ND ND NO
Carbazole 20 NO ND NO NO
Carbofuran 5 NO ND NO NO
Carbon disulfide 87 7.4 NO 5.1 NO
Carbon tetrachloride 40 NO ND ND NO
Chlorobenzene 32 NO ND NO NO
Chloroethane 62 NO ND NO NO
Chloroform 49 6.6 2.7 2.6 NO
Chloromethane 36 NO NO NO NO
Chromium (total) 40 3.5 5.0 12 13
Chrysene 17 NO NO NO ND
Cobalt 45 11 2.0 20 4.7
Copper 120 10 9.5 15 20
Cyanide 75 NO 13 8.7 3.6
Delta-BHC 0 0.026 NO NO NO
DI-n-butylphthalate 20 7.3 5.7 5.5 10
DI-n-octylphlhalate 22 NO NO 8.3 7.8
Dibenzofuran 15 NO NO ND ND
Dibromochloromethane 27 5.5 NO NO NO
Dicamba 4 NO NO NO NO
Dieldrin 0.19 NO ND ND ND
DEN100153BO.WP5
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..-
~
u-
V,)
Table 14-1
Chemkal CODCwtration Data Summary Page 5 of 5
95th Pen:wtile Upper Confidence Limit on the Geometric Mean of the Median Well CODCwtratioDS
(pgll)
SbaIIow Ground-water Monitoring Ground-water Monitoring Ground-water Monitoring Deep Ground. Upgradleot Ground-
Wells Completed In Weathered Wells Completed In Wells Completed In water water Monitoring
Dawson and Waste Pit Liquids Well Weathered Dawson Aquifer Unweathered Dawson Aquifer Monitoring Wells Outsid.e the
Chemical Name Points Within the Soun:e Area Outside of the Soun:e Area Outside of the Soun:e Area Wells Source Area
Nickel 230 25 9.5 33 30
PCB-I 242 (Aroclor 1242) 2.03 ND ND ND ND
PCB-1248 (Aroclor 1248) ND ND ND ND ND
PCB-1260 (Aroclor 1260) 2.3 ND ND ND ND
Pentachlorophenol 130 ND ND ND ND
Phenanthrene 36 ND ND ND ND
Phenol 120 7.3 5.7 6.2 6.9
Propoxur ND ND 0.92 ND ND
Pyrene 20 7.3 ND ND ND
Selenium 170 29 5.1 2.4 100
Silver II 3.5 3.8 ND 2.8
Styrene 38 ND ND ND ND
Tetrachloroethylene 190 37 3.4 18 3.5
Thallium 61 6.5 1.6 2.8 ND
Tin 480 40 28 ND ND
Toluene 1,600 4.9 2.3 13 2.6
Total xylenes 930 15 ND 9.2 ND
Trichloroethylene 250 27 2.9 7.4 2.9
Vanadium 130 15 6.1 15 26
Vinyl chloride 99 8.5 ND ND ND
Zinc 410 37 24 40 110
Note: ND = Not detected.
"2,3,7 ,S-Dimon equivalent concentration.
-------
Section 15.0
Bibliography
-------
Section 15.0
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DEN 100 1 54FA.WP5
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