United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R01-89/041
September 1989
&EPA
Superfund
Record of Decision
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50272-101
REPORT DOCUMENTATION 11. REPORTNO. .
PAGE EPA/ROD/R01-89/041
2.
3. Reclpienh Acce88lon No.
4. Title and Sublltle
SUPERFUND RECORD OF DECISIO~
Saco Tannery Waste Pits, ME
First Remedial Action - Final
7. Author(a)
5. Report Date
09/27/89
-
8.
8. Pwfonnlng Organlz8l1on Rept. No.
8. Perfonnlng Orgalnlz8l1on Heme and AcId....
10. ProjectlTa8klWork Unit No.
11. Contrect(C) or Grant(G) No.
(C)
(G)
12. ~orIng Organizetlon Heme and Addr...
U.S. Environmental Protection
401 M Street~ S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
Agency
800/000
14.
1 S. Supplementary Notea
16. Abetract (Umlt: 200 worda)
The Sa co Tannery Pits site is in Saco, Maine, approximately 15 miles southwest of
Portland, Maine. The 233-acre site is in a rural area which includes forests and
wetlands, and lies within the lOO-year floodplain of Stuart Brook. Between 1959 and the
early 1980s a leather tannery operator used the site to dispose of process wastes in two
2-acre lagoons and 53 smaller disposal pits. EPA and State investigations in the early
1980s led to a removal response action which included pumping liquids from three waste
pits and neutralizing the remaining sludge from the pits. This Record of Decision
addresses both source control and ground water remediation and identifies a contingency
plan in the event the State legislature fails to enact the necessary institutional
controls within two years. The primary contaminants of concern affecting the sediment,
sludge, ground water, and surface water are metals including arsenic, chromium, and
lead.
The selected remedial action is contingent upon the State enacting legislation within
two years designating the site as a permanent conservation area. The remedy includes
pumping and offsite treatment and discharge of water from waste pits and lagoons
followed by covering and revegetating waste pits, lagoons and associated wet areas;
compensation for six acres of lost wetlands; ground water and surface water monitoring
(See Attached Sheet)
17. Documenl AMly.l. L De.crlptors
Record of Decision - Sa co Tannery Waste Pits, ME
First Remedial Action - Final
Contaminated Media: sludge, sediment, gw, sw
Key Contaminants: metals (arsenic, chromium, lead)
b. Identiller8l0pen-Ended Terme
"
c. COSA TI Reid/Group
18. Avellabldty Stetement
18. Security CI..a (ThIs Repor1)
None
20. Secwlty CI..s (ThIs Page)
Nnnp
21. No. 01 Pagea
128
22. PrIce
,
(See ANSI-l39.18)
See Inatructiona on Reve-
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OPTIONAL FORM 272 BACK
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EPA/ROD/ROl-89/041
Sa co Tannery Waste Pits, ME
First Remedial Action
16.
Abstract (Continued)
, .
to determine whether contaminants exceed specified action levels which would require
further site evaluation; and implementation of institutional controls. If legislation
is not passed to restrict future use of the site, a contingency plan will be implemented
which includes excavating and solidifying soil and sludge from the waste pits and
lagoons with onsite disposal in a RCRA-permitted landfill, and ground water and surface
water monitoring. The estimated present worth cost for the selected remedial action
ranges from $9,211,600 to $10,551,400, which includes present worth O&M costs ranging
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\
".
ROD SUMMARY
SACO TANNERY WASTE PITS SITE
SACO, MAINE
SEPTEMBER 27, 1989
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Contents
I.
II.
A.
B.
C.
III.
IV.
V.
A.
B.
C.
D.
VI.
VII.
VIII.
A.
B.
IX.
A.
B.
x.
A.
B.
C.
XI.
A.
B.
C.
D.
E.
. .
Saco Tannery Waste Pits site
Record of Decision Summary
TABLE OF CONTENTS
Paqe Number
SITE NAME, LOCATION AND DESCRIPTION. . . . .
. . .
SITE HISTORY AND ENFORCEMENT ACTIVITIES. . . . . .
Response History Prior to Issuance of the first
Proposed Plan ..................
Issuance of the first Proposed Plan and the revised
Proposed Plan. . . . . . . . . . . . . . . . . . .
Enforcement History. . . . . . . . . . . . . . . .
COMMUNITY RELATIONS
. . .
. . . . . . . . . .
. . .
SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION
SITE CHARACTERISTICS. . . . . . . . . . . . . . .
Soil. . . . . . . . . . . . . . . . . . . . . . .
C;~OtlI1ciVia1:e~ . . . . . . . . . . . . . . . . . . . .
Surface Water and Sediments. . . . . . . . . . . .
Wetlands and Floodplains. . . . . . . . . . . .
SUMMARY OF SITE RISKS. . .
. . . .
. . .
. . . .
DOCUMENTATION OF SIGNIFICANT CHANGES
. . .
. . .
DEVELOPMENT AND SCREENING OF ALTERNATIVES. . . . . 15
Statutory Requirements/Response Objectives. .. 15
Technology and Alternative Development and screening 16
DESCRIPTION/SUMMARY OF THE DETAILED AND COMPARATIVE
ANALYSIS OF ALTERNATIVES. . . . . . . . . . . .
Source Control (SC) Alternatives Analyzed. . . .
Groundwater Alternatives (GW) Alternatives Analyzed
THE SELECT.ED REMEDY. . . . . . . . . . . . . . .
Description of the Selected Remedy. . . . . . .
Description of Remedial Components. . . . . . . .
Rationale for Selection. . . . . . . . . . . . . .
STATUTORY DETERMINATIONS ............ 48
The Selected Remedy is Protective of Human Health and
the Environment. . . . . . . . . . . . . . . . . . 49
The Selected Remedy Attains ARARs . . . . . . . .. 50
The Selected Remedial Action is Cost Effective 54
The Selected Remedy utilizes Permanent Solutions
and Alternative Treatment or Resource Technologies
to the Maximum Extent Practicable. . . . . . . .. 55
The Selected Remedy Does not Satisfy the
Preference for Treatment as a Principal Element. . 56
1
2
2
2
3
3
4
6
6
7
9
10
10
14
18
18
23
25
25
30
38
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XII.
XIII.
A.
B.
C.
XIV.
A.
B.
C.
D. .
E.
STATE ROLE !" ".
. . . .
. . . . .
. . . .
. . . . . .
56
THE ALTERNATE REMEDY. . . . . . . . . . . . . . .
Description of the Alternate Remedy. . . . . . . .
Description of Remedial Components. . . . . . . .
Rationale for Selection of an Alternate Remedy
57
57
58
62
STATUTORY DETERMINATIONS FOR ALTERNATE REMEDY. .. 63
The Alternate Remedy is Protective of Human Health and
the Environment. . . . . . . . . . . . . . . . .. 63
The Alternate Remedy Attains ARARs . . . . . . .. 64
The Alternate Remedial Action is Cost Effective.. 69
The Alternate Remedy Utilizes Permanent Solutions and
Alternative Treatment or Resource Technologies to the
Maximum Extent Practicable. . . . . . . . . . .. 69
The Selected Remedy Satisfies the Preference for
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sacoTannery Waste pits site
Record of Decision Summary
~ST OF FIGURES
Piqure Number
Paqe Number
.Figure 1 Site Location Map . . . . . . . . . . . . . . . . 1a
Figure 2 site Plan . . . . . . . . . . . . . . . . . . . . 1b
Figure 3 Floodplain Map . . . . . . . . . . . . . . . . . lOa
Figure 4 Waste pit Cover System . . . . . . . . . . . . . 31a
Figure 5 Lagoon 1 Cover System . . . . . . . . . . . . . . 31b
Figure 6 Lagoon 2 Cover System . . . . . . . . . . . . . . 31c
Figure 7 site Location Map - Residential Well Sampling Area 36a
Figure 8 Site Plan . . . . . . . . . . . . . . . . . . . . 47a
Figure 9 site Location Map - Residential Well Sampling Area 61a
LIST OF TABLES
Table Number
Paqe Number
Table 1 Frequency of Occurrence of Detected Compounds . . 11a
Table 2 Phase II Contaminants of Concern . . . . . . . . lIb
Table 3 Average and Maximum Concentrations for Phase II
Contaminants of Concern . . . . . . . . . . . . . 11c
Table 4 Phase I Risk Characterization . . . . . . . . . . lId
Table 5 Summary of Phase II Risk Characterization . . . . lIe
Table 6 Initial Remedial Alternative Screening Summary 18a
Table 7 Comparitive Summary of Alternatives . . . . . . . 18b
Table 8 Cost Estimate:Alternative SC-3A . . . . . . . . . 38a
Table 9 Chemical Specific ARARs . . . . . . . . . . . . . 50a
Table 10 Location Specific ARARs . . . . . . . . . . . . . 50b
Table 11 Action Specific.ARARs for Selected Remedy . . . . 50c
Table 12 Remedial Alternatives Cost Comparison . . ... . . 55a
Table 13 Chemical Specific ARARs . . . .... . . . . . . . . 65a
Table 14 Location Specific ARARs . . . . . . . . . . . . . 65b
Table 15 Action specific ARARs for Alternate Remedy . . .. - 65c
APPENDICES
Responsiveness Summary. . . . . . . . . . . . .
Administrative Record Index. . . . . . . . . . .
Technical Memos - Target Levels .........
State Concurrence Letter. . . . . . . . . . . . .
Appendix A
Appendix B
Appendix C
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'. "
DECLARATION FOR THE
RECORD OF DECISION
SITE NAME AND LOCATION
Saco Tannery Waste Pits site
Saco, Maine
STATEMENT OF PURPOSE
This Decision Document represents the selected remedial action
for the Saco Tannery Waste Pits site in Saco, Maine developed in
accordance with the Comprehensive Environmental Response,
Compensation and Liability Act of 1990 (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA),
and to the extent practicable, the National Contingency Plan
(NCP) 40 C.F.R. Part 300 et sea. (1985). The Regional
Administrator for Region I of the United States Environmental
Protection Agency has been delegated the authority to approve
this Record of Decision.
The remedial action chosen for the Saco Tannery Waste pits site
includes the selected remedy, and an alternate remedy which will
be effective in the event that the selected remedy cannot be
implemented. The state of Maine has concurred on the selected
and alternate remedy and has determined that these remedies are
consistent with applicable and relevant and appropriate Maine
laws and regulations. The State of Maine also agrees to
implement and enforce the institutional controls and land use
restriction components of the selected remedy and the alternate
remedy.
STATEMENT OF BASIS
This decision is based on the administrative record which was
developed in accordance with Section 113(k) of CERCLA. The
,attached index (Appendix B to the ROD) identifies the items which
~comprise the administrative record upon wh.ich the selection of
-the remedial action is based.
The Administrative Record is available for public review at the
Dyer Library at 371 Main Street in Saco, Maine and the EPA Region
I Waste Management Division Records Center at 90 Canal street in
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ASSESSMENT OF THE SITE
. .
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action
selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare and the environment.
DESCRIPl'ION OF THE SELECTED REMEDY
The selected remedy for the Saco Tannery Waste pits site
comprehensive remedy that combines both a source control
groundwater component. The selected remedy includes the
followi~g components:
is a
and
1. The contaminated sludge
will be contained by installing a
the threat of direct contact with
sludges.
in the waste pits and lagoons
cover system that will minimize
and ingestion of soils and
2. To assure that the soil cover is protected from future
destruction, and that future development of the Site is
prohibited, the Site is to be converted into a permanent state
conservation area pursuant to an act of the Maine state
legislature. This state statute requirement (i.e., legislatively
created institutional controls) is designed to provide a highly
effective means to limit the future uses of the site property.
3. To address the threat of future leaching of chromium
from the waste to the groundwater, a groundwater monitoring
network will be established to monitor for releases of chromium.
In the event chromium is detected in monitoring wells located on
site at levels in excess of the MCL for chromium (50 ppb), an
evaluation of the need for additional remedial action will be
conducted. In the event chromium is detected in monitoring wells
at or around the property boundary at levels in excess of ten
times the current MCL for chromium, or 500 ppb, a source area
treatment alternative-will be selected and implemented.
4. To address the groundwater contamination detected at
the Site, groundwater monitoring to determine the levels and
movement of arsenic and other contaminants will be also be
conduct~d. with-respect to arsenic, an Alternate Concentration
Limit '(ACL) for arsenic will be the relevant. and appropriate
standard for four on-site monitoring wells. The" relevant and
appropriate groundwater standards for all other site contaminants
will be the Safe Drinking Water Act Maximum Contaminant Levels
(MCLs). EPA will evaluate the need for additional remedial
action at the site in the event that groundwater monitoring
reveals any of the following conditions: site related
groundwater contaminants other than arsenic are detected in on-
site monitoring wells at levels greater than their MCLs; site
related groundwater contaminants, including arsenic, are detected
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'"
~~
..
',.'
.,,~:.
levels greater than their MCLs;ior arsenic levels in four
specific on-site monitoring wells exceed the ACLs established for
arsenic at those wells. . Furtheri evaluation of the Site will also
be conducted if contaminal"'!t concentrations above AWQC are
detected in on-site identifiable streams because of discharge of
site related groundwater contaminants into surface water.
DESCRIPI'ION OF THE ALTERNATE REMEDY
This Record of Decision includes an alternate plan in the
that the state statute required under the selected remedy
enacted. This alternate plan will also be implemented in
event that EPA finds that the necessary state statute is
inadequate. If an adequate state statute is not enacted and in
effect within two years from September 27, 1989, the execution
date of this ROD, the alternate cleanup plan for the site will
become effective.
event
is not
the
Under the alternate cleanup plan, the soils and sludges from the
waste pits and lagoons will be excavated and solidified, and the
solidified materials will be placed in a RCRA hazardous waste
landfill to be constructed on-site. In addition, groundwater
monitoring would be performed as an interim remedy.
DECLARATION CONCERNING THE SELECTED REMEDY
The selected remedy is protective of human health and the
environment, attains federal and state requirements that are
applicable or relevant and appropriate for this remedial action,
is cost-effective and utilizes permanent solutions and
alternative treatment technologies to the maximum extent
practicable. The remedy does not utilize treatment and thus does
not meet the preference for remedies that employ treatment as a
principal element.
Additionally, because the remedy would result in contaminants
remaining on-site, EPA will review the site at least once every
five years after the initiation of the remedial action. at the
Site to ensure that the remedial action continues to be
protective of human health and the environment.
DECLARATION CONCERNING THE ALTERNATE REMEDY.
The source control component of the alternate remedy is .
protective of human health and the environment, attains federal
and state requirements that are applicable or relevant and
appropriate for this remedial action, is cost-effective and
utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable. The remedy
utilizes treatment and thus meets the preference for remedies
that employ treatment as a principal element.
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ROD DECISION SUMMARY
I.
SITE NAME, LOCATION AND DESCRIPl'ION
The Saco Tannery Waste Pits site (the STWP site or the Site) is
located in the City of Saco, approximately 15 miles southwest of
.Portland, Maine. The 233-acre site is bordered by the Maine
Turnpike to the east, residential property along Hearn Road to
the west, the Saco-Scarborough town line to the north, and Flag
Pond Road to the south (see Figure 1).
Between 1959 and about the early 1980's, a leather tannery
operated the 233-acre STWP site as a disposal area for process
wastes. Wastes from the tanning process were reportedly disposed
in two lagoons, each roughly two acres in size, and 53 smaller
disposal pits (see Figure 2). The total surface area of
contamination is approximately 13 acres.
The majority of the Site is forested; unforested land consists of
disturbed areas, wetlands, and bedrock outcrops. Both manmade
and naturally occurring wetlands are found on site. Manmade
wetlands include the two large lagoons and many of the 53 waste
pits on site. A lOa-year floodplain is located within the
property boundaries, but neither the waste pits or lagoons are
located within the floodplain.
The site is located in a rural, residential area. There are
approximately 50 single family homes located within a half-mile
radius of the Site. Residential development is concentrated
along Jenkins and Hearn Roads (see Figure 1). The Maine Turnpike
is located on the eastern border of the Site, limiting
development in that direction. Residents who live near the site
obtain their water from private drinking wells, and rely on
groundwater,for their water supply. The groundwater aquifer in
the area of the Site is classified under federal standards as
IIB, suitable for public water supplies.
The site includes two surface water drainageways in the western
and northern portions of the Site. Both drainageways originate
in the swampy region west of Waste pits 7, 8, and 9 (see Figure
2). One drainage continues south as a swampy stream with poorly
defined channels to a culvert under Flag Pond Road. The second
drainage flows north and then east, in a well-defined channel, to
a confluence with a more northern tributary to form Stuart Brook.
Stuart Brook flows southeast through a culvert under the Maine
Turnpike.
A more complete description of the site can be found in section
2.0 of the Phase II Remedial Investigation Report and also in
section 1.1 of the Feasibility Study. A more complete
description of the wetlands and floodplains can be found in the
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The groundwater component of the alternate remedy is an interim' -
remedy. statutory requirements for the groundwate~ component of
the alternate remedy will be met when a final groundwater remedy
is selected. .
Additionally, because the alternate remedy would result in
contaminants remaining on-site, EPA will review the site at least
once every five years after the initiation of the remedial action
at the site to ensure that the remedial action continues to be
protective of human health and the environment.
~j;J7 j 7,
V Date
(C;r/ 7
?ud ;j ~A'
Regional Admini~trator,
Region I U.S.
Environmental Protection
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.u.DR.H',I.E 1..:<:,U10~ SITE LOCATION MAP
SACO TANNERY WASTE PITS SITE
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ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 2
II.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
A.
Response History Prior to Issuance of the first
proposed Plan
Investigations by the Maine Department of Environmental
Protection (DEP or the state) and the united states Environmental
Protection Agency (EPA or the Agency) in the early 1980's led to
the site being placed on the National Priorities List in
September 1983. From July through october 1983, EPA, in a
removal response action at the STWP site, remediated three acid
pits which posed an immediate and significant risk to human
health. EPA pumped the liquid from the pits, neutralized the
remaining sludge with lime, capped the pits, and erected a fence
around portions of the site property.
From 1985 to 1987 DEP, under a Cooperative Agreement with EPA,
conducted an initial Remedial Investigation (Phase I RI) to
determine (1) physical site conditions: (2) contamination
resulting from waste disposal at the site: and (3) health and/or
environmental risks associated with the wastes. EPA initiated a
Phase II RI and a Feasibility study in October 1987 to address
issues raised during the Phase I RI: to meet the requirements of
the superfund Amendments and Reauthorization Act of 1986 (SARA):
and to evaluate potential remedial alternatives for the site and
provide the information necessary to select a remedy.
A more detailed description of the site history can be found in
section 2.2 of the Phase II Remedial Investigation Report.
B.
Issuance of the first proposed Plan and the revised
proposed Plan
In July 1988, EPA released its first Proposed Plan to address
contamination at the STWP site. Following the issuance of. the
first proposed Plan;... DEp.indicated that it would not concur with
EPA"s preferred alternative. The DEP refused to concur 'with
EPA's preferred alternative, in part, for reasons of cost-
effectiveness. without DEP's concurrence, and absent DEP's
agreement to assist in paying for the costs of the cleanup, the
proposed cleanup plan could not be implemented. In view of DEP's
comments, EPA reassessed the remedial alternatives considered in
the FS and amended one of the source control alternatives
considered in the FS. This amended source control alternative
was described and evaluated in the FS Addendum, which was
released in June 1989. Additionally, in June 1989, EPA released
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" '.
ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 3
contained in the RI and FS.
In June 1989, EPA issued a revised Proposed Plan in which it
altered its original recommendations for remedial action at the
site. This Record of Decision adopts as the remediation plan for
.the Site the preferred alternative recommended in the revised
Proposed Plan.
C.
Enforcement History
On June 2, 1988, EPA notified three (3) parties who owned or
operated the facility, generated wastes that were shipped to the
facility, arranged for the disposal of wastes at the facility, or
transported wastes to the facility of their potential liability
with respect to the site. Negotiations have not commenced with
these potentially responsible parties regarding the settlement of
the PRPs' liability at the Site.
One of the PRPs submitted comments on both the first Proposed
Plan and the revised Proposed Plan. These comments and EPA's
responses are included in the Responsiveness Summary.
III.
COMMUNITY RELATIONS
Throughout the Site's history, community concern and involvement
has been moderate to high. EPA and DEP have kept the community
and other interested parties apprised of the Site activities
through informational meetings, fact sheets, press releases and
public meetings.
In '.the winter of 1984-85, DEP released ~ community relations plan
which outlined a program to address community concerns and keep
citizens informed about and involved in activities during
remedial activities.
ori May 8" 1985, DEP and EPA held an in~9rmational meeting at the
Dy~r Library located on. Main Street i~~aco to describe the plans
for ~he Remedial Investigation and Feasib~lity Study.
On May 14, 1986, DEP and EPA held an informational meeting at the
Dyer Library to present the findings of the investigations to
date.
On December 3, 1987, EPA and DEP held an informational meeting at
the Dyer Library to present the findings of the Phase I Remedial
Investigation, and to describe the plans for the Phase II
-------
ROD DECISION SUMMARY', .
SACO TANNERY WAsTE PITS SITE
Paqe 4
EPA published a notice and brief analysis of the
Plan in the Journal Tribune on July 26, 1988 and
available to the public at the Dyer Library. On
EPA made the administrative record available for
offices in Boston and at the Dyer Library.
first Proposed
made the plan
August 3, 1988,
review. at EPA's
'On August 2, 1988, EPA held an informational meeting at the Dyer
Library to discuss the results of the Remedial Investigations and
the cleanup alternatives presented in the Feasibility study and
to present the first Proposed Plan. Also during this meeting,
the Agency answered questions from the public. From August 3 to
August 24, 1988, the Agency held a three week public comment
period to accept public comment on the alternatives presented in
the Feasibility study and the first proposed Plan and on the
other documents which were a part of the administrative record
for the site. On August 16, 1988, the Agency held a public
hearing to accept any oral comments. A transcript of this
hearing and the comments and the Agency's response to comments
are included in the attached responsiveness summary.
EPA published a notice and brief analysis of the revised Proposed
Plan in the Journal Tribune on June 26, 1989 and made the plan
available to the public at the Dyer Library. On July 11, 1989,
EPA made an administrative record addendum available for public
review, along with the administrative record, at EPA's offices in
Boston and at the Dyer Library. On July 11, 1989, EPA held an
informational meeting at the First Parish Congregational Church
located on Beach street in Saco to review the results of the
Remedial Investigations and the cleanup alternatives presented in
the Feasibility Study and to present the Agency's revised
proposed Plan. Also during this meeting, the Agency answered
questions from the public. From July 12 to August 2, 1989, the
Agency held a three week public comment period to accept public
comment on the alternatives presented in the Feasibility study
and the revised Proposed Plan and on the other documents which
were a part of the administrative record and the administrative
record addendum for. the Site. On July 25, 1988, the Agency held
a public hearing to accept any oral comments. A transcript of
this hearing. and the comments and the Agency's response to
comments are included in the attached responsiveness summary.
IV.
SCOPE AND ROLE OF OPERABLE UNIT OR RESPONSE ACTION
The selected remedy was developed by combining both a source
control and groundwater component to obtain a comprehensive
approach for site remediation. In addition, an alternate
remedial plan was adopted for this site in the event that the
-------
ROD DECISION SUMMARY" ' .
SACO TANNERY WASTE PITS SITE
Page 5
remedy and the alternate remedy include the following components:
1. The contaminated'sludge
will be contained by installing a
the threat of direct contact with
sludges.
in the waste pits and lagoons
cover system that will minimize
and ingestion of soils and
2. To assure that the soil cover is protected from future
destruction, and that future development of the site is
prohibited, the Site is to be converted into a permanent state
conservation area pursuant to an act of the Maine State
legislature. This state statute requirement (i.e.,
legislatively-created institutional controls) is designed to
provide a highly effective means to limit the future uses of the
site property.
:3. To address the threat of future leaching of chromium
from the waste to the groundwater, a groundwater monitoring
network will be established to monitor for releases of chromium.
In the event chromium is detected in monitoring wells located on
site at levels in excess of the MCL for chromium (50 ppb), an
evaluation of the need for additional remedial action will be
conducted. In the event chromium is detected in monitoring wells
at or around the property boundary at levels in excess of ten
times the current MCL for chromium, or 500 ppb, a source area
treatment alternative will be selected and implemented.
4. To address the groundwater contamination detected at
the Site, groundwater monitoring to determine the levels and
movement of arsenic and other contaminants will be also be
conducted. with respect to arsenic, an Alternate Concentration
Limit (ACL) for arsenic will be the relevant and appropriate
standard for four on-site monitoring 'wells. The relevant and
appropriate groundwater standards for all other site contaminants
will be the Safe Drinking Water Act Maximum contaminant Levels
(MCLs). EPA will evaluate the need for additional remedial
" action at the site in the event that groundwater monitoring
. reveals any of the following conditions: site related
~ -!groundwater contaminants other than ~rsenic are detected in on-
s'ite monitoring wells at levels greater than their MCLs i site
related groundwater contaminants, including arsenic, are detected
in monitoring wells located at or around the site boundary at
levels greater than their MCLsi or arsenic levels in four
specific on-site monitoring wells exceed the ACLs established for
arsenic at those wells. Further evaluation of the Site will also
be conducted if contaminant concentrations above AWQC are
detected in on-site identifiable streams because of discharge of
-------
ROD DECISION s.UMHARy'. .
SACO TANNERY WASTE PITS SITE
Paqe 6
5. Finally, as indicated above, this Record of Decision
also includes an alternate plan in the event that the necessary
state statute, and regulations or agreements implementing the
,state statute, are not enacted or adopted. This alternate plan
will also be implemented in the event that EPA finds that the
, necessary state statute, regulations, or agreements are
inadequate. If an adequate state statute, and regulations or
agreements implementing the state statute, are not passed,
adopted, and in effect within two years from september 27, 1989,
the execution date of this ROD, the alternate cleanup plan for
the Site will become effective. Under the alternate cleanup
plan, the soils and sludges from the waste pits and lagoons will
be excavated and solidified, and the solidified materials will be
placed in a RCRA hazardous waste landfill to be constructed on-
site. The alternate remedy is discussed in section XIII.
v.
SITE CHARACTERISTICS
Section 1.0 of the Feasibility study contains an overview of the
?emedial Investigations. The significant findings of the
Remedial Investigations are summarized below.
A.
Soil
1.
Waste pits
The STWP site includes 53 waste pits ranging in size from
approximately 1,395 to 57,940 square feet. In general, waste pit
soils are characterized by high concentrations of chromium (on
the order of 10,000 ppm) and lead (on the order of 100 to 1,000
ppm), often accompanied by VOC and/or SVOC contamination. VOCs
were detected in 19 samples from waste pits, three of these
samples contained high VOC concentrations of greater than 100
ppm. SVOCs were detected in 40 samples from waste pits, seven of
these samples contained high SVOC concentrations greater than 100
ppm.
Soil cont~minant concentrations immediately adjacent to waste
pits are two to four orders of magnitude lower than those within
the waste pits, which indicates that the highly contaminated
soils are generally restricted to the waste pits.
vertically, soil contaminant concentrations decrease immediately
below or underneath the visibly contaminated waste sludge. The
most common contaminant detected below the sludge was chromium,
which was found in concentrations of 1,950 ppm and 3,660 ppm more
than two feet below the sludge in two waste pit borings.
-------
ROD DECISION SUMMARY.
SACO TANNERY WASTE PITS' SITE
Paqe 7
sludge were generally low, i.e., below 1,000 ppm. In samples
collected from below the sludge, VOCs and SVOCs either were not
detected, or were detected at very low levels.
The Phase I and Phase II Remedial Investigations support the
following characterization of the waste pits:
*
The nature of the waste sludge found in the pits does
not differ significantly between waste pits, with the
exception of the three waste pits that were neutralized
and capped during EPA's 1983 removal action.
*
High levels of contamination are restricted to the
waste pit interiors. Concentrations of site
contaminants appear to return to background levels in
soils directly outside the waste pits. In two
locations on-site, however, contamination is not
restricted to the waste pit interiors. The western
berm of Waste pit 9 is incomplete and, as a result,
sediments have flowed from the pit and into an adjacent
wet swampy area. In addition, there is a seep area
outside the northern berm of Chromium Lagoon 2
containing contaminated sediments.
*
EP Toxicity analyses of waste samples indicate that
chromium has some potential to leach (particularly
under acidic conditions) from the waste to groundwater.
However, groundwater analyses indicate that chromium is
not migrating from the sludge under current conditions,
and has not migrated into the groundwater in the many
years since disposal began.
2.
Chromium Lagoons and Filled Areas
The STWP site includes two large chromium lagoons.
in the lagoons has two general characteristics:
contamination
*
The contamination found within the lagoons is similar
to that observed in the waste pits on~site. The
average thickness of sludge found in the lagoons is .
greater than the average thickness found in the waste
pits.
The filled area in the southern portion of Chromium
Lagoon 2 contains sludge, similar to that in the waste
pits, and solid waste in the form of leather hides and
strips not encountered elsewhere on-site.
*
B.
-------
ROD DECISION sUMMARy.. .
SACO TANNERY WASTE PITS SITE
Paqe 8
The Phase I and Phase II groundwater investigations support the
following characterization of groundwater conditions:
*
*.
1.
On-site groundwater conditions
Arsenic is the single groundwater contaminant present
on-site at concentrations greater than its MCL.
No definable source of arsenic was identified in the
wastes or soils on-site. Arsenic is not a
characteristic contaminant of tannery wastes, and
arsenic concentrations within the pits have not been
found to be significantly higher than those found
outside the pit areas. One sediment sample taken from
the seep area outside Chromium Lagoon 2 contained
sufficient arsenic to be initially considered as a
potential contaminant source to groundwater; however,
no arsenic contamination was detected in groundwater
from that area.
*
organic groundwater contaminants were detected on-site
at levels significantly below MCLs or health-based
groundwater standards. The source of these
contaminants appears to be the contaminated sludge
present in the waste pits and chromium lagoons.
*
Arsenic contamination and low levels of organic
contaminants were detected in groundwater monitoring
wells located in the overburden and shallow bedrock.
Neither arsenic or organic contamination was detected
in the three deep bedrock wells on site.
2.
Off-site groundwater conditions
*
Residential wells sampled in the Site vicinity did not
reveal any contaminant levels in excess of MCLs.
*
Under current conditions, there is no evidence of any
hydraulic connection between the residential wells and
the STWP site. Based on local and regional topography,
the regional groundwater movement in the Hearn Road
area is generally moving from the residential wells
eastward towards the on-site wetlands and streams. In
addition, groundwater movement demonstrated in the on-
site monitoring wells indicates upward flow and
discharge of groundwater to on-site surface water. The
hydrogeologic investigation indicates that the effects
-------
. ~ . '.
ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 9
not felt in on-site monitoring wells.
*
The hydrogeologic investigation indicates that under
existing conditions the arsenic and low levels of
organic contaminants detected in groundwater beneath
the site are not expected to be drawn into residential
wells in the Site vicinity. However, future
development in the site vicinity, resulting in
additional groundwater withdrawal, could affect
groundwater conditions and cause contaminant migration
off-site.
C.
Surface Water and Sediments
Surface water and sediments were sampled in the Phase I and Phase
II investigation programs. contamination was generally limited
to tne following areas:
*
As stated above, in two locations on-site,
contamination is not restricted to the waste pit
interiors. The western berm of Waste Pit 9 is
incomplete, providing a path for contaminated soil to
move into a wet swampy area as entrained sediment in
overland flow. In addition, there is a seep area
outside the northern berm of Chromium Lagoon 2
containing contaminated sediments.
*
Sediment in the wet swampy area west of Waste pit 9
contained high concentrations of chromium and lead.
Decreasing concentrations of chromium and lead in
sediment samples trace a path of contamination from the
back of Waste pit 9 to a location 1000 feet downstream
. in the surface water drainage leading to stuart Brook.
Surface water sampling in this drainage found chromium
and lead in concentrations exceeding the respective
AWQC stan9ards. Chromium levels of 31 and 21 ppb
exceed both the acute and chronic standards. Lead
concentrations at 5.6 ppb exceed the chronic standard.
These elevated concentrations appear to be caused by
overland flow over the contaminated wet area behind
Waste pit 9. Further downstream, levels of chromium
and lead attenuate to below background or undetectable
levels.
*
The seep area outside the northern berm of Chromium
Lagoon 2 contained the highest concentration of arsenic
detected on site. Chromium lagoon samples were not
analyzed for arsenic: however, contaminated materials
-------
. f
ROD DECISION SUMMARY'
SACO TANNERY WASTE PITS SITE
*
Paqe 10
and waste pit soils analyzed did not contain
significant arsenic. Thus, the specific source of
arsenic detected in the seep area is unknown.
Arsenic, at low levels, was detected in off-site stream
sediments collected from a location upstream of the
pits and lagoons (SED-103). The presence of arsenic at
locations upstream of the pits and lagoons indicates
that arsenic levels on-site cannot be attributed solely
to the Site.
*
standing water in the waste pits and lagoons, as
represented by a sample from Waste pit 33, contained
elevated concentrations of chromium, lead, and a
limited number of organic compounds.
A complete discussion of site contamination can be found in
section 7.0 of the Phase II Remedial Investigation Report.
D.
Wetlands and Floodplains
A Wetlands and Floodplains Assessment Report was prepared to
supplement the data contained in the RI and FS. The significant
findings are summarized below:
VI.
*
The STWP site includes portions of the 100-year
floodplain for stuart Brook (Figure 3). stuart Brook
is located on the north and northeast portions of the
site. The area of the 100-year floodplain is
approximately 30 acres. Neither the waste pits,
chromium lagoons, the Chromium Lagoon 2 seep area, or
the wet area behind Waste pit 9 are located within the
100-year floodplain. Chromium Lagoons 1 and 2 are
approximately 120 feet and 440 feet respectively from
the floodplain. The nearest waste pits are numbers 1
and 18 which are approximately 370 feet and 330 feet
respectively from the floodplain~
* .
Approximately 53 acres of the site: are covered by .
wetlands. These wetlands consist of approximately 47.
acres of naturally occurring wetlands and 5.85 acres of
manmade wetlands, which were created as a result of
human activities. The manmade wetlands include
Chromium Lagoons 1 and 2 and a number of the waste
pits.
SUMMARY OF SITE RISKS
-------
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-------
ROD-DECISION.SUMMARY,
SACO TANNERY WASTE PITS SITE
Paqe 11
site was performed in conjunction with the Phase I RI -Report.
The Phase I assessment was conducted to provide a risk
characterization of the current baseline conditions. section 9.1
of the Phase II RI Report 'summarizes the results of the Phase I
Baseline Risk Assessment.
Additionally, a Public Health Supplemental Risk Assessment was
conducted to evaluate risk to public health assuming future
residential use. This assessment was based on sampling data
generated during the Phase II RI. Section 9.0 of the Phase II RI
Report provides a detailed discussion of the Supplemental Risk
Assessment.
Table 1 summarizes the frequency of detection of all Phase II
contaminants at the STWP site by location and chemical group;
Table 2 lists the contaminants of concern for the Supplemental
Risk Assessment. Table 3 lists the average and maximum
concentrations for Phase II contaminants of concern. These
contaminants constitute a representative subset of the
contaminants identified on-site in both the Phase I and Phase II
RIs. contaminants of concern were selected to represent
potential on site hazards based on toxicity, level of
contamination, mobility, and persistence in the environment.
Potential human health effects associated with the contaminants
of concern in groundwater, soil, surface water, and sediment were
estimated quantitatively through the development of several
hypothetical exposure scenarios. Incremental lifetime cancer
risks and a measure of the potential for noncarcinogenic adverse
health effects were estimated for the various exposure scenarios.
Exposure scenarios were developed to reflect the potential for
exposure to hazardous substances based on the characteristic uses
and location of the site.
Table 4 summarizes the risk characterization for the Phase I
Baseline Risk Assessment. Table 5 presents a summary of the
Phase II risk characterization for future residential use.
=At'the STWP site, it is reasonable to assume that the site will
~be used for residential purposes in the future, if such use is
not precluded by the remedial actions. : Saco, like many areas of
southern Maine, is experiencing an increase in residential homes
and year-round residents. continued population growth in Saco
and southern Maine will increase the pressure for residential
development in the vicinity of the site.
The conclusions from the Phase I and Phase II Public Health Risk
Assessments are summarized below. (The carcinogenic risk
estimates are reported as either below the target range when
-------
TABLE 1
fREQUENCY Of OCCURRENCE Of DETECTED rnMPOUNDSa
SACO TANNERY WASTE PITS Sill
SACO. MAINE
Groundwater ~QU Sedim~nt ~urface W!!~er
Monitoring Well Uncontaminated Contaminated Uncontaminated Contaminated
Samples Soil/Waste Areas Areds Areas Areas
..-
- _.
.'i(,ANICS .
.--
,,,,,illiurn 3/32 68/68 6/6 6/6 3/6 0/2
r.- 1/32 18/68 0/6 1/6 0/6 0/2
j ...q-illnlony
Arsenic 11/32 52/68 5/6 1/6 0/6 0/2
Calcium 32/32 58/68 4/6 6/6 6/6 2/2
(iJdrnium 0/32 27/68 5/6 1/6 0/6 0/2
...-
Chromium 1/33 1121114 6/6 6/6 1/6 2/2
Copper 0/32 5 5/68 6/6 5/6 6/6 2/2
Iron 25/32 68/68 616 6/6 6/6 2/2
Lead 2/32 11 21114 6/6 6/6 3/6 1/2
Magnesium 27/32 68/68 4/16 1/6 3/6 1/2
Manganese 29/32 68/68 616 6/6 3/6 2/2
Mercury 1/32 18/68 1/6 2/6 0/6 0/2
~..
Nickel 3/32 42/68 4/6 1/6 0/6 0/2 '
.
Selenium 0/32 0/68 0/6 2/6 0/6 0/2
Silver 0/32 0/68 0/6 1/6 0/6 0/2
Sodium 31/32 3/68 0/6 1/6 6/6 1/2
Zinc 4/32 68/68 616 6/6 6/6 1/2
'1:J
Il>
f)q
ro
f-'
f-'
III
~
f-'
-------
TABLE 1 (continued)
FREQUENCY OF OCCURRENCE OF DETECTED COMPOUNDSa
SACO TANNERY WASTE PITS SITE
SACO, MAINE
-
Groundwater Soil ~ediment '. Surface Water
Monitoring Well Uncontaminated Contaminated Uncontaminated Contaminated
Samples SoillWaste Areas Areas Areas Areas
!
ORGANICS
2-Butanone 2/32 8/1 08 0/6 0/2 0/6 0/2
Toluene 1/32 ' 11/1 08 0/6 0/2 0/6 0/2
Chlorobenzene 7/32 9/108 0/6 0/2 0/6 1/2
Ethylbenzene 2/32 20/1 08 0/6 0/2 0/6 0/2
Diethylphthalate 0/32 1/108 0/6 0/2 0/6 0/2
Di-n-butyl phthalate 0/32 1/1 08 0/6 0/2 0/6 0/2
Di-n-octyl phthalate 1/32 0/108 0/6 0/2 0/6 0/2
1.1.1- Trichloroethane 0/32 1/1 08 0/6 0/2 0/6 0/2
Bis (2-ethylhexyl) 5/32 18/1 08 0/6 0/2 0/6 0/2
phthalate
Phenol 1/32 6/1 08 0/6 02 0/6 0/2
2.4,5- Trichlorophenol 0/32 3/108 0/6 0/2 0/6 0/2
2.4,6- Trichlorophenol 0/32 1/108 0/6 0/2 0/6 0/2
2-Methylphenol 2/32 0/108 0/6 0/2 0/6 0/2
4-Methylphenol 1/32 1 0/1 08 0/6 0/2 0/6 0/2 '
1,4-Dichlorobenzene 2/32 5/108 0/6 0/2 0/6 0/2
1.3-Dichlorobenzene 0/32 1/108 0/6 0/2 0/6 0/2
1.2- Dichlorobenzene 5/32 20/108 0/6 0/2 0/6 0/2
'l:J
P>
O"Q
ro
,......
,......
P>
.--..
-------
Groundwater ~oil Sediment . Surface Water
Monitoring Well Uncontaminated Contaminated Uncontaminated Contaminated
Samples Soil/Waste Areas Areas Areas Areas
ORGANICS
Naphthalene 1/32 8/1 08 0/6 0/2 0/6 0/2
1,2,4- Trichlorobenzene 0/32 2/108 0/6 0/2 0/6 0/2 ..
.
. ! r..1r:thyl naphthalene 0/32 4/108 0/6 0/2 0/6 0/2
~
Pentachlorophenol 0/32 4/1 08 0/6 0/2 0/6 0/2
4-Chloroaniline 0/32 1/108 0/6 0/2 0/6 0/2
lot lexanone 0/32 2/108 0/6 0/2 0/6 0/2
' ... ,.-...-.
. I 'o'lhyl-2-pentanone 0/32 3/108 0/6 0/2 0/6 0/2
--
:.;..: II Iylene chloride 0/32 1/108 0/6 0/2 0/6 0/2
Xylenes 0/32 26/108 0/6 0/2 0/6 0/2
! .-
n(.TICIDES
"
1!-1254 0/32 1/108 0/6 0/2 0/6 0/2
-
,.'<-DOE 0/32 1/1 08 0/6 0/2 0/6 0/2
I
~ ...
.1,4 -ODD 0/32 0/108 0/6 1/2 0/6 0/2
,
TABLE 1 (continued)
FREQUENCY OF OCCURRENCE OF DETECTED COMPOUNDSa
SA CO TANNERY WASTE PITS SITE
SACO. MAINE
'lJ
PJ
()Q
(i)
~
~
PJ
d
I.ilies do not include duplicates or blanks.
,......
w
-------
TAB
PHASE II CONA T AMINANTS OF CONCERN
SACO TANNERY WASTE PITS SITE
SACO, MAINE
I Groundwater ~oil Sediment . Surface Water
Monitoring Well Uncontaminated Contaminated Uncontaminated Contaminated
Samples Soil/Waste Areas Areas Areas Areas
(t,JORGANICS
I . dd""
::,,",ony X X
",
i ""f,enic X . X X X
Cadmium X X X
Chromium X X X X X
_. ... -
, X X X X X
; .d lese X X X X X
._-
I iVIEf(Ury X X X
1-"-
VOCs -..-
Chlorobenzene X X X
SVOCs
Bis (2-ethylhexyl) X X
phthalate
Phenol X ,
2,4,6- Trichlorphenol X
'\:I
OJ
0:1
ro
I-'
~
-------
TABLE 3
A VERAGE AND MAXIMUM CONCENTRA TION FOR
PHASE II CONTAMINANTS OF CONCERN
SACO TANNERY WASTE PITS SITE
SACO, MAINE
Groundwater SOlllSludqe ~Q!...l!.!ent ~urfa~_YVater
(ugll) (ug/g) Uncontaminated Areas Contaminated Areas Uncontaminted Areas Contaminated Areas
(ug/g) (ug/g) (ug/I) (ug/I)
Average MalCimum" Average MalClmuma Average MalClmuma Average MalClmuma Average MalCimuma Average MalClmuma
--
INORGANICS
Antimony 60 463 222 1050
ArseniC 168 79 8.9 33 125 31 224 1210
lddmlum 1/1 (est.) b 23 12 NE 65 118 55
Chromium III (est.) b 14500 57025 NE 69 12266 49903
( IHomlum VI (est.) b 667 2625 NE 3 565 2297 8 21 992 3270
i - ._,.,
I,~~~~ 3.4 25 175 1260 NE 31 2011 630 93 20
! I,,;,'flganele 2120 8270 NE 1700 NE 4740 555 3260 226 361
F-~i';;;Ury 1.1 13 NE 0.73 NE 5
VOCS
Chlorobenzene 15 ...,-r 180 5.8 - 130 11 20
.
I
.-
i SVOCs
---.
B,s (2-ethylhelCyl) phthalate 556 1500 NE 33
! f 1',(,f101 NE 120
.....--
I' . :-,Iorphenol 3 13
-
'1j
OJ
UQ
(D
I-'
I-'
n
,.1. -1 MalClmum wncentratlon did not contribute to a RealistIC Worst-case total car'
',i,I,,,nu. .ny sample including duplicates.
Total chromium, but not chromium VI, was measured 10 surface water. Since chromium VI, the more t01C1C form 01 lhromlum, IS more soluble In water than, hromlum IJI
.. 0
'!nlC fISk above 10- 7 nor to a RealistIC Worst-lase total Hazard IndelC above 1 0
.,
-------
TABLE 4
PHASE I RISK CHARACTERIZATION
CURRENT BASELINE CONDITIONS. TRESPASSER SCENARIO
SACO TANNERY WASTE PITS SITE
SACO, MAINE
CARCINOGENIC RISK NONCARCINOGENIC RISK
UPPER.BOUND EXCESS lifE TIME HAZARD INDEX
CANCER RISK CHEMICALS CONTRIBUTING MOSl CHEMICALS
EXPOSURE SCENARIO TO RISK CONTRIBUTING
RE AliS TIC MOST TO RISK
MOST PROBABLE REALISTIC MOS T PROBABLE
CASE . WORS T CASE CASE WORST CASE
Groundwater - Ingestion 7 h10"" 4 4.10.) Arsenic, (Cadmlum)b. b,s(2. 1 2 2.2 Lead. Cadmium
ethylhe.yl) phthalate
Soil. Dermal Absorption and 13.10.(, 2.4.10.) (Chromium VI)b 1.711 10.2 1.3 Lead
Ingestion
Sediments. Dermal Absorption 6.4.10.(, 5.6.10.6 Arsenic, (Cadmlum)b 40.10.6 10.10.2 -----....
SUI face Water. Ingestion .------ .-.---- ------...... 9.hI0.S 26.10.) a--,,-.._--
i
: '..e. Inhalation during 53x10.S B6.10.) (Chromium VI)b 36.10.1 7 h10' 1 Chromium III. lead
., ...IIIJtlon Activities
a
b
Assuming a dust concentration level of 50mg/m3.
Assuming cadmium and chromium are carcingoenoc by ingestion and dermal absorption. an assumption which IS not recognized by the EPA CAG
'U
III
OQ
CD
t-'
t-'
-------
TABLE 5
SUMMARY OF PHASE II RISK CHARACTERIZATION
FUTURE RESIDENTIAL USE
SACO TANNERY WASTE PITS SITE
SACO, MAINE
.
CARCINOGENIC RISK NONCARCINOGENIC RISK
UPPER-BOUND EXCESS LIFETIME HAZARD INDEX
CANCER RISK CHEMICALS CONTRIBUTING MOST CHEMICALS
EXPOSURE SCENARIO CONTRIBUTING
TO RISK
MOST PROBABLE REALISTIC MOST TO RISK.
MOST PROBABLE REALISTIC
CASE WORST CASE CASE WORST CASE
Groundwater. Ingestion 72E-4 3.11£-3 ArseniC. bis(2-ethylheKyl) phthalate 5.3EI 11.5 BEHP.lead.
Manganese
50il.Waste - Dermal Absorption II BE-1 1I.8P ArseniC 611E.1 104 Lead. Antimony.
and Ingestion Chromium VI (est)
Sediment {(ontaminanted) - 77E-6 69E-4 Arsenic 75£.1 37 Lead. Antimony.
Dermal AbsorptIon and Ingestion Chromium VI (est.)
Sediment (Uncontaminanted) - 42E.1 t7P Arsenic N£ 66E-1 .a__............
Dermal Absorption and Ingestion
Surface Water (Contaminated) - -----.... ------- --..........-.. 51[-1 II 7E1 ---...---...
Dermal Absorption
Surface Water (Uncontaminated). .........- ------- ....-........-.. 6.2E'" 99£-3 -------......
Dermal Absorption
NE a Not evaluated. Hazard Indell for realistic worst-case is less than 1.0; therefore. most-probable case will be even less.
>u
III
()Q
(I)
t-'
t-'
-------
ROD" DECISION SUMMARY -
SACO TANNERY WASTE PITS SITE
Paqe 12
between 10.7 and l0.~i or above the target range when the risks
are greater than 10 .)
*
An increased carcinogenic risk to public health above
the target range was seen for ingestion of groundwater
on-site from exposure to arsenic assuming future
residential use.
*
Assuming future residential use, given a realistic
worst case, noncarcinogenic risk from ingestion of
manganese, chlorobenzene, lead and bis(2-
ethylhexyl)phthalate detected in the groundwater had a
Hazard Index of 4.5. This exceeds the target Hazard
Index of 1.0. However, adverse systemic effects would
not be expected for this exceedance of the Hazard Index
because, when considering the effects of these
contaminants individually rather than as a group, the
individual contaminant levels are believed to lie
within the boundary of uncertainty which indicates no
noncarcinogenic risks. Under the most probable
scenario, the noncarcinogenic risk from ingestion of
these groundwater contaminants was less than the Hazard
Index of 1.0.
*
An increased carcinogenic risk to public health within
the target range was seen for dermal contact with and
ingestion of the soil/waste from exposure to arsenic
under future residential use. An increased
noncarcinogenic risk was seen under the realistic
worst-case scenario from dermal exposure to and
in~estion of lead, antimony, and estimated chromium
VI .
*
An increased carcinogenic risk to public health within
, For the compound chromium (Cr), the risk to public health
was evaluated for both Cr III and Cr VI. Cr III (trivalent
chromium) has: a very low human toxicity, whereas Cr VI
(hexavalent;chromium) has a much greater toxicity. -. Soil samples
were generally analyzed for total chromium (i.e. Cr III and Cr VI
combined), however, a limited number of samples were analyzed for
both total chromium and hexavalent chromium. The maximum
percentage of Cr VI found to be present in samples which were
analyzed for both total Cr and Cr VI was found to be 4.4 percent.
For purposes of the risk assessment, this value was then used to
compute an estimated concentration of potentially present Cr VI
in all soil samples. The estimated Cr VI concentration was then
subtracted from the total Cr concentration to obtain an estimated
-------
ROD" DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 13
the target range was seen for dermal contact with and
ingestion of sediment from contaminated areas from
exposure to arsenic under future residential use. An
increased noncarcinogenic risk from exposure to lead,
cadmium, and estimated chromium VI was seen under the
realistic worst-case scenario.
*
No increased carcinogenic or noncarcinogenic risk to
public health was seen from dermal contact with surface
water.
*
The Phase II air sampling results for VOCs at the waste
pit locations did not differ from the levels at the
background location near the Maine Turnpike. Based on
the EPA CAG value for benzene, the maximum levels of
benzene detected at both the background location and
the waste pit locations are at the 10-6 carcinogenic
risk for lifetime exposure. Although no chromium or
SVOCs were detected in the air, an increased health
risk was seen for remedial site workers using
conservative risk assumptions and estimating air
concentrations from soil levels. (Appropriate health
and safety measures will be used during remediation.)
Section 10.0 of the Phase II RI Report provides a detailed
discussion of the Ecological Risk Assessment performed for the
STWP site. The Ecological Risk Assessment identifies and
characterizes the environments that may be exposed to
contamination originating from the STWP site, and evaluates
risks to environments at the site based on ecotoxicity
information.
The conclusions of the Ecological Risk Assessment include the
following:
*
Communities of aquatic fauna are depressed in the areas
of high chromium concentrations found in the waste pits
,
and c,hrom~um lagoons.
..
,. .~.
*
Aquatic organisms appear to be at little 01: no risk
from environmental contamination at Stuart Brook.
*
Aquatic and terrestrial organisms that use the lagoons
and waste pits/wetlands for habitat and food are
probably at risk where sediment concentrations exceed
2,000 ppm chromium and surface water concentrations
exceed 11 ppb chromium.
Based on the public health and ecological risk assessment, actual
-------
ROD DECISION SUMMARY"
SACO TANNERY WASTE PITS SITE
Paqe 14
not addressed by implementing the response actions sele~ted in
this ROD, may present an imminent and substantial endangerment to
public health, welfare, or, the environment.
A summary of the risks posed by the STWP site can be found in
sections 1.3 and 1.4 of the Feasibility Study.
VII.
DOCUMENTATION OF SIGNIFICANT CHANGES
The first Proposed Plan for the Saco Tannery Waste pits site was
released for public comment in July 1988. The first Proposed
Plan identified Alternative SC-5 (excavation, solidification, and
landfilling) and GW-2 (groundwater monitoring) as the preferred
alternative. Due to the State's refusal to concur on the
proposed remedy, in part for reasons of cost-effectiveness, EPA
revised its proposed plan, as explained in section X.C.1. of this
ROD. .
The revised Proposed Plan for the STWP site was released for
public comment in June 1989. The revised Proposed Plan
identified Alternatives SC-3A and GW-2 (soil cover system,
legislatively-created institutional controls, and groundwater
monitoring) as the preferred alternative. In addition, the
revised Proposed Plan included an alternate remedy in the event
that the state legislature fails to enact the necessary
institutional controls. The alternate remedy in the revised
Proposed Plan is Alternative SC-5 and GW-2, the remedial
alternative recommended in EPA's first Proposed Plan.
EPA has made three significant changes to the revised Proposed
Plan. First, the revised Proposed Plan does not include target
cleanup levels for soils and sediments. This ROD include~ soil
and sediment target,"cleanup levels for lead, antimony, arsenic,
and chromium. The target level for chromium was provided in the
Remedial Investigation and was available to the public in the
Administrative Record, but the target levels for lead, antimony,
and arsenic werefihalized during the public comment period and
have not been previously available to the public. These'.,target
levels, as a whole', ,will be of practical significance at" only two
limited areas of the site. All of the waste pits and lagoons at
the site will be subject to remediation under both the selected
remedy and the alternate remedy. However, in two locations of
the site where contaminated sediments will be addressed, the
target levels will be used to delineate the extent of the area to
be covered with the soil cover system.
Second, the revised Proposed Plan indicates that under
Alternative SC-3A, a groundwater mor.itoring network would be
-------
ROD' DECISION" SUMMARY. '.
SACO TANNERY WASTE PITS SITE
Paqe 15
wastes begin to migrate from the sludge at significant -levels.
In this ROD, EPA has specified the details of the groundwater
monitoring program and selected contingencies for further actions
or evaluations at the Site. In particular, EPA has determined
that in the event that chromium is detected at levels in excess
of 500 ppm in monitoring wells located at or around the site
boundary, a further remedy that involves treatment of the wastes
at the site will be performed. The details concerning the
monitoring program and contingencies for future actions were
developed during the public comment period. These details do not
alter the projected cost of the selected alternative.
Finally, EPA has established Alternate Concentrations Limits
(ACLs) as the groundwater remediation standard for arsenic under
the selected remedy. Although ACLs were not discussed in the
revised Proposed Plan, EPA did indicate that groundwater
monitoring for arsenic would be performed. Subsequent to the
release of the revised Proposed Plan, EPA determined that the
standards for ACLs were met with respect to arsenic contamination
at the Site. The inclusion of ACLs in this ROD does not alter
the scope of the selected remedy, which will require groundwater
monitoring for arsenic.2
VIII.
DEVELOPMENT AND SCREENING OF ALTERNATIVES
A.
Statutory Requirements/Response Objectives
Prior to the passage of the Superfund Amendments and
Reauthorization Act of 1986 (SARA), actions taken in response to
releases of hazardous substances were conducted in accordance
with CERCLA as enacted in 1980 and the revised National oil and
Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR
Part. 300, dated November 20, 1985. Although EPA proposed
revisions on December 21, 1988, to the NCP to reflect SARA, until
those proposed revisions are finalized, the procedures and
standards for respo~ding to releases of hazardous substances,
pollutants and contaminants shall be in accordance with Section
2 Several minor changes to the Revised Proposed Plan have
also been made, generally in response to comments made by the
State. These minor changes include: the use of a rock and
gravel layer in the soil cover at selected waste pits, rather
than at all waste pits; the installation of a fence surrounding
the soil cover system construction area, rather than surrounding
the entire Site; and the installation of monitoring wells at and
around the site property boundary and in the interior of the
Site, rather than along a perimeter line enveloping all of the
-------
ROD" DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 16
121 of CERCLA and to the maximum extent practicable, the current
NCP.
Under its legal authorities, EPA's primary responsibility at
Superfund sites is to undertake remedial actions that are
protective of human health and the environment. In addition,
.Section 121 of CERCLA establishes several other statutory
requirements and preferences, including: a requirement that EPA's
remedial action, when complete, must comply with applicable or
relevant and appropriate environmental standards established
under federal and state environmental laws unless a statutory
waiver is granted; a requirement that EPA select a remedial
action that is cost-effective and that utilizes permanent
solutions and alternative treatment technologies or resource
recovery technologies to the maximum extent practicable; and a
statutory preference for remedies that permanently and
significantly reduce the volume, toxicity or mobility of
hazardous wastes over remedies that do not achieve such results
through treatment. Response alternatives were developed to be
consistent with these Congressional mandates.
In the risk assessment and environmental assessment, several
potential exposure pathways were analyzed for risk and threats to
public health and the environment. Guidelines in the Superfund
Public Health Evaluation Manual (EPA, 1986) regarding the
development of risk analyses for remedial alternatives were used
to assist EPA in the development of response actions. As a
result of these assessments, the following remedial action
objectives were developed to mitigate existing and future threats
to public health and the environment:
*
Minimize exposure to contaminants or reduce
contaminants to levels that are protective of human
health and the environment.
*
Reduce the threat of future leaching of chromium or
reduce the levels of chromium in the sludge that could
leach into the groundwater in the future.
* .: Prevent ingestion of contaminated. groundwater.
*
Minimize exposure 'of wildlife to contaminated soil,
sediments, and standing water.
B.
Technology and Alternative Development and Screening
CERCLA, the NCP, and EPA guidance documents including, "Guidance
on Feasibility Studies Under CERCLA" dated June 1985, the
"Interim Guidance on Superfund.Selection of Remedy" [EPA Office
-------
ROD' DECISION SUMMARY',
SACO TANNERY WASTE PITS SITE
Paqe 17
9355.0-19 (December 24,1986), and t~e Interim Final ~Guidance
for Conducting Rls and FSs under CER-":LA," OSWER Directive No.
9355.3-01 (October 1988), ,set forth the process by which remedial
actions are evaluated and selected. In accordance with these
requirements and guidance documents, a range of treatment
alternatives were developed for the Site, a containment option
.involving little or no treatment, and a no-action alternative.
section 121(b) (1) of CERCLA presents several factors that at a
minimum EPA is required to consider in its assessment of
alternatives. In addition to these factors and the other
statutory directives of Section 121 of CERCLA, the evaluation and
selection process was guided by the EPA document "Additional
Interim Guidance for FY '87 Records of Decision" (OSWER Directive
9355.0-21) dated July 24, 1987. This document provides direction
on the consideration of SARA cleanup standards and sets forth
nine factors that EPA should consider in its evaluation and
selection of remedial actions. The nine factors are:
L
Overall Protection of Human Health and the Environment.
2.
Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs).
3.
Long-term Effectiveness and Permanence.
4.
Reduction of Toxicity, Mobility or Volume.
Short-term Effectiveness.
5.
6.
Implementability.
7.
Community Acceptance.
8.
state Acceptance.
9.
Cost.
Section 4.0 of the Feasibility Study identified, assessed and
screened technologies to. determine if the technology is an . .
acceptable engineering practice that could provide an
implementable, feasible and practicable remedy. These
technologies were combined into source control (SC) and
groundwater (GW) alternatives. section 5.0 in the Feasibility
Study presented the remedial alternatives developed by cOmbining
the technologies identified in the previous screening process in
the categories required by OSWER Directive No. 9355.0-19. The
purpose of the initial screening was to narrow the number of
potential remedial actions for-further detailed analysis while
-------
ROD-DECISION. SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 18
evaluated and screened in Section 6.0 of the Feasibility Study.
In summary, of the 13 source control and groundwater remedial
alternatives screened in $ection 6.0, 12 were retained for
detailed analysis. Table 6 identifies the 12 alternatives that
were retained through the screening process, as well as. those
that were eliminated from further consideration. After deciding
to reconsider the first Proposed Plan, EPA amended one of the
source control alternatives (Alternative SC-3) contained in the
FS by including additional safeguards to human health and the
environment. This amended source control alternative
(Alternative SC-3A) is described in the addendum to the FS.
IX.
DESCRIPrION/SUMMARY OF THE DETAILED AND COMPARATIVE
ANALYSIS OF ALTERNATIVES
This section presents a narrative summary and brief evaluation of
each 'alternative according to the evaluation criteria described
above. sections 7.0 (source control alternatives) and section
8.0 (groundwater alternatives) of the Feasibility Study contain
the detailed analyses' of each remedial alternative that passed
the initial screening in Section 6.0. The FS Addendum contains a
detailed analysis of Alternative SC-3A. See Table 7 for a
detailed tabular assessment of each alternative.
A.
Source Control (SC) Alternatives Analyzed
The source control alternatives analyzed for the site include a
minimal no action alternative (SC-1); institutional action (SC-
2); cover system (SC-3); cover system with monitoring network and
institutional controls (SC-3A); in-situ sOlidification/
stabilization (SC-4); excavation/solidification/on-site RCRA
landfill (SC-S); excavation/solidification/on-site disposal area
(SC-6); excavation/on-site RCRA landfill (SC-7); excavation/soil-
washing (SC-9); excavation/on-site incineration eSC-10).
SC-l
No Action
This alternative is developed for each Superfund site to
assess impacts on public health and the environment if no
measures are taken to remediate current site conditions, and
to serve as a comparison to other remedial alternatives
considered. No technical or institutional methods would be
used to reduce potential exposure. The no-action
alternative would be selected only if the site posed little
or no risk to public health and the environment. At the
Saco Tannery Waste pits site, the no-action alternative
would not provide adequate. protection of human health and
the environment.
-------
Page 18a
TABLE 6
INITIAL REMEDIAL ALTERNATIVE SCREENING SUMMARY
SACO TANNERY WASTE PITS SITE
SACO. MAINE
ALTERNATIVES ALTERNATIVES
ALTERNATIVE RETAINED FOR ELIMINATED IN
DETAilED INITIAL
ANALYSIS SCREENING
SC-' No Action SC-'
SC-2 Institutional Actions SC-2
SC-3. Cover System SC-3
SC-4 In-SItu Sol idi ficatlon SC-4
SC-5 Excavation/Solidification/On-site RCRA Landfill SC-5
SC-6 Excavation/Solidification/On-site Disposal Area 5C-6
SC-7 Excavation/On-site RCRA Landfill 5C-7
SC-8 Excavation/Solidification/Off-site RCRA Landfill 5C-8
SC-9 Excavation/Soil Washing SC-9
SC-lO Excavatlon/lnci neration SC-' 0
-..
GW-, No Action . GW-,
GW-2 Institutional Actions GW-2
GW-3 Pump and Treat by GW-3
-------
Page 18b (1)
COMPARATIVE
TABLE 7
SUMMARY OF SOURCE CONTROL REMEDIAL ALTERNATIVES.
SACO TANNERY WASTE PITS SITE
SACO, MAINE
LONG TERM REDUCTION OF
SHORT TERM EFFECTIVENESS MOB I LI TV, TOXICITY IMPLEMENT- COMPLIANCE OVERALL
I, 111l~TJ1I E FFECTI VENESS AND PERFORMANCE OR VOLUME lli!J.!! WITH ARARS PROTECTION
5C-I: No Action Fails to reduce Magnitude of risk No reduction In Five-year review Does not c~ly No protection to
potential for remains unchanged. mobility, necessary. with RCRA or Maine pub I ic health and..
direct contact. Potential for toxicity, or closurel post- the envi ronnent.
Site threats to contaminant volume cI osure ARAR I s
public health and leaching to ground
the envirorvnent water not
not addressed. addressed.
Remedial action
objectives not
achieved.
SC-2: Reduces direct Potential for No reduction In Fences readily Does not c~1 y Minimal protection
Institutional contact by contaminant mobil i ty, constructable. with RCRA or Maine to public health
Actions restricting site leaching to toxicity, or Legal services for closurel post- and the
access and through groundwater not volume. institutional cI osure ARARs. environnent
inst i tut ional addressed. controls required. provided by fence
controls. and institutional
Remedial action controls.
objectives not
-------
Pagp l8b (2)
LONG TERM
EFFECTIVENESS REDUCTION OF
SHORT TERM AND MOBILITY, TOXICITY IMPLEMENT- C(JIPLIANCE OVERALL
ALTERNATIVE EFFECTIVENESS PERFORMANCE OR VOLUME lli!.!!!. IIITH ARARS PROTECTION
SC-3: Cover System Reduces potential Potential for No reduct ion In Cover system Coopl ies with Risk from direct
for direct contaminant mobility, readi I y ARARs. contact controlled
contact. Limited leaching to toxicity, or constructable. by cover soils.
envi ronnental groundwater not volume of sludge. Services and cover Potential for
I""acts during addressed. Pl.q)ing ponded materials future groundwater
cover placement. Monitoring water reduces available. impacts not
Remedial action required to assess volume of Remedial work addressed.
objectives future groundwater contaminated approximately 1.5 Environmental
achieved in 1.5 i""acts. surface water. years. impacts from
years. Objectives ponded water In
to reduce threat pits/lagoons
or potential for reduced.
future leaching C~nsatory
not achieved. wettand area to be
constructed.
SC-3A: Cover Reduces potential Potential for No reduction In Cover system Coopli es wi th Risk from direct
System for direct contact contaminant mobilitv toxlcltv, readil y ARARs. contact controlled
and ingestion. leaching to ground or volume of constructable. by cover soils.
Limited water remains sludge. P~ing Services and cover Potential for
envi rormentsl Monitoring ponded water materials future groundwater
impacts during required to assess reduces volume of available. contamination
cover placement. future leaching. contaminated Remedial work addressed by
Remedial action Contingency plan surface water. approximately 1.7 contingency plan.
objectives exists to address years. Environmental
achieved in 1.7 potential future impacts form
years. Objectives contaminant ponded water in
to reduce migration. pits/lagoons
potential for Designation of reduced.
future leaching conservation area C~nsatory
addressed by minimizes wetland area to be
establishment of potential for constructed.
monitoring network disturbance of
and contingency cover or use of
-------
AL TERNA TI VE
SC-4: In-situ
Sol idificationl
Stabilization
SHORT TERM
EFFECTIVENESS
Reduces potential
for direct
contact. Addresses
potential for
future contaminant
leaching to
groundwater, but
solidified wastes
remain below water
table. Remedi al
action objectives
achieved in 1.5
years. I n- s itu
solidification is
not feasible for
sol id waste
contaminat ion.
LONG TERM
EFFECTIVENESS AND
PERFORMANCE
Potential for
contaminant
teaching reduced
by solidification
treatment. Putty-
tike sludge
hinders effective
in-situ mixing of
studge and
sotidification
reagents.
Moni toring
required to assess
future groundwater
iq>acts.
REDUCTION OF
MOBILITY ,
TOXICITY OR VOLUME
Contaminant
mobil i ty reduced
through
sol idification
PUq>ing ponded
water reduces
volume of
contaminated
surface water.
IMPLEMENT-
llili!.!
In-situ
solidification
services
avai lable.
Intimate mixing of
sludge with
reagents unlikely
given pasty nature
of sludge. Process
not compatible
with sol id waste
disposed in fill
area. Remedial
work approximately
1 to 2 years.
COMPLIANCE
III TH ARARS
Compl ies with
ARARs. .
Page l8b (3)
OVERAll
PROTECTION
Risk from direct
contact controlled
by cover soils
over sol idified
sludge. Risks to
workers associated
with sludge
handling during
in-situ treatment
addressed through
health and safety
protection.
Potential for
future groundwater
iq>acts reduced.
Envi ronmentat
impacts from
ponded water in
pits/lagoons
reduced.
Compensatory
wetland area to be
-------
AL TERNA TI VE
SC-s: Excavation/
Solidification
On-site RCRA
landfill
SHORT TERM
EFFECTIVENESS
Sludge excavation
reduces potential
for direct contact
and significantly
reduces potential
for future
leaching of
contaminants to
groundwater.
Considerable
remedial
construction
activities may
I~ct
envlronnental
habitats. Source
control objectives
achieved In three
to four years.
LONG TERM
EFFECTIVENESS AND
PERFORMANCE
Remedy reliable
since sludge
posing risk is
removed. Addresses
potential for
contaminant
leaching to
groundwater. RCRA
landf ill I s a
rel iable
technology with
little potential
for fai lure.
Leachate
collection systems
installed in
landfill. Batch
solidification
more effect I ve
than in-situ
mixing.
REDUCTION OF
MOBILITY, TOXICITY
OR VOLUME
Contaminant
mobi l I ty reduced
through
solidification
treatment and RCRA
landfill. P~ing
ponded water
reduces volume of
contaminated
surface water.
IMPlEMENT-
lli!.!.!!
Significant sludge
excavation and
landf ill
construction
necessary.
Solidification
well demonstrated
on sludge.
Services and
materials
available. Solid
waste would be
placed In
landfill. Remedial
work approximately
3 to 4 years.
COMPLIANCE
WITH ARARS
Complies with
ARARs.
Page 18h (4)
OVERALL
PROTECTION
Risk from direct
contact controlled
by excavation and
landfill 109. Risks.
to workers
associated with.
sludge excavation.
addressed through
heal th and safety:""
protection.
Potential for
future groundwater
IqJacts frOm
sludge eliminated..
Waste
consolidation and
treatment
achieved.
Envlronnental
iqJacts from
ponded water In
pits/lagoons
reduced.
Compensatory
wetland area to
-------
ALTERNATIVE
SC-6: Excavation /
Sol idiflcation/
On-Site Disposal
SHORT TERM
EFFECT IVENESS
Sludge excavation
reduces potential
for direct contact
and significantly
reduces potential
for future
leaching of
contaminants to
groundwater.
Considerable
remedial
construction
activities may
i~ct
envlronnental
habitats. Source
control objectives
achieved In 3 to 4
years.
lONG TERM
EFFECTIVENESS AND
PERFORMANCE
Remedy rei fable
since sludge
posing risk is
removed. Addresses
potential for
contaminant
leaching to
groundwater. Batch
solidification
more effective
than in-situ
mixing. Disposal
area does not
employ synthetic
liners or leachate
collection
systems. Disposal
area not as
protective as RCRA
landfill over the
long term.
REDUCTION OF
MOBiliTY, TOXICITY
OR VOLUME
Contaminant
mobil i ty reduced
through treatment.
Purping ponded
water reduces
volume of
contaminated
surface water.
IMPlEMENT-
lli.!:.l!!
Significant sludge
excavation and
disposal area
construction
necessary.
Sol idification
well demonstrated
on sludge.
Services and
materials
available. Sol id
waste would be
placed in disposal
area. Remedial
work approximately
3 to 4 years.
COMPLIANCE
YITH ARARS
Does nOt comply
with RCRA landfill
requirements.
Page l8b (5)
OVERAll
PROTECTION
Risk from direct
contact controlled
by excavation and
on-site disposal.
Risk to workers
associated with.
sludge excavation
addressed through
health and safety
protection.
Potential for
future groundwater
i~cts from
sludge reduced.
Yaste
consolidation and
treatment
achieved.
Envi ronmental
I~cts from
ponded water In
pits/lagoons
reduced.
C~nsatory
wetland area to be
-------
AL TERNATIVE
SCoT:
Excavation/On-Site
I'U!!\. landfill
SHORT TERM
EFFECTIVENESS
Sludge excavation
reduces potential
for direct contact
and significantly
reduces potential
for future
leaching of
contami nants to
groundwater.
Considerable
remedial
construction
activities may
i"""ct
envi ronmental
habitats. Source
control objectives
achieved In 3 to 4
years.
LONG TERM
EFFECTIVENESS AND
PERFORMANCE
Remedy rei iable
since sludge
posing risk Is
removed. Addresses
potential for
contaminant
leaching to
groundwater. RCRA
I andf ill Is a
reliable
technology,
however without
treatment of the
wastes, longterm
effectiveness
remains uncertain.
leachate
coltectlon systems
installed In
landf Ill. RCRA
landfllt design
must account for
longterm
sett I ement of
untreated sludge.
REDUCTION OF
MOBiliTY, TOXICITY
OR VOLUME
Contaminant
mobil i ty reduced
through RCRA
landf i II. P~lng
ponded water
reduces volume of
contaminated
surface water.
IMPLEMENT-
ABILITY
Significant sludge
eJtcavation and
hndf ill
construction
necessary.
Services and
materials
available.
landfill design
must account for
geotechnical
properties of
untreated sludge.
Solid waste would
be placed in
landfill. Remedial
work approJtimately
3 to 4 years.
C(J4PlIANCE
"ITH ARARS
Coa.,l ies with
ARARs.
Page l8b (6)
OVERAll
PROTECTION
Risk from direct
contact controlled
by eJtcavation and
landfilling. Risks
to workers
associ ated wi th .
sludge eJtcavation
addressed through
health and safety
protection.
Potential for
future groundwater
I"""cts from
sludge reduced.
"aste
consol idatlon
achieved.
Environmental
IlJ1)acts from
ponded water In
pits/lagoons
reduced.
Coq>ensatory
wetland area to be
-------
AL TERNATIVE
5C-8:
Excavation/
Sol idificatlon
Off-Site RCRA
landf i II [not
considered for
detailed analysis
in the feasibility
study)
SC-9: Excavation/
Soil Washing
SHORT TERM
EFFECTIVENESS
...---...
Sludge excavation
reduces potential
for direct contact
end significantly
reduces potential
for future
leaching of
contaminants to
groundwater.
Considerable
remedial
construct Ion
ectlvltles. May
i.ct
envirorrnental
habitats. Source
control objectives
achieved in more
than 5 years since
soil washing
technology
requires further
deve I opnent .
LONG TERM
EFFECTIVENESS AND
PERFORMANCE
---..-..---
Addresses
potential for
contaminant
leaching to
groundwater.
Reliability of
soil washing
technology
uncertein. o&M and
process control
requirements
difficult to
define.
REDUCTION OF
MOBILITY, TOXICITY
OR VOLUME
-...-----
Contaminant
mobility reduced
through
excavation. Soil
washing process
decreases
contaminant volume
but would generate
other contaminated
media requiring
treatment. Pumping
ponded water
reduces volume of
contaminated
surface water.
IMPLEMENT-
!!!ill!
Significant sludge
excavation
necessary. Soi I
washing process
not proven for
sludge matrix and
would requi re
extensive
deve I opment .
pilot-testing, and
special ists.
Process not
coopatible with
solid waste
disposed in fill
area. Remedial
work greater than
5 years.
COMPlI ANCE
WITH ARARS
--..-...........
Coop I I es wi th
ARARs.
Page 1 Bb
(7)
OVERAll
PROTECTION
Risk from direct
contact controlled
by excavation and
soil washing
treatment. Risks
to workers
associated with
sludge excavation
addressed through
health and safety
protection.
Envl ronmentel
impacts from
ponded water In
pits/lagoon
reduced.
Compensatory
wetland are to be
-------
AL TERNATIVE
5C-10
Excavation/On-Site
Incineration
SHORT TERM
E HECTI VENESS
Sludge eKcavatlon
reduces potential
for direct contact
and significantly
reduces potential
for future
leaching of
contaminants to
groundwater.
EKtensive remedial
construction
activities and
trial burn
necessary.
Emissions modeling
necessary. Source
control objectives
achieved In about
5 years.
LONG TERM
EFFECTIVENESS AND
PERFORMANCE
Remedy reliable
since sludge
posing risk Is
removed. Addresses
potential for
contaminant
leaching to
groundwater.
. Residual materials
likely to be
hazardous and
would require
appropriate
management.
Potential for
resource recovery
of chromiun, but
costs eKceed value
of recovered
material. Resource
recovery process
requires further
development.
REDUCTION OF
MOBILITY, TOKICITY
OR VOLUME
Incineration
reduces volume of
sludge and
destroys organic
constituents.
Contaminant
mobil ity and
tOKiclty may be
Increased and
residual material
would require
secondary waste
management.
Reduces volume of
contaminated
surface water.
IMPLEMENT-
lli!J.!!
Significant sludge
excavation
necessary.
Incineration
destroys organic
constituents but
does not treat
inorganics.
Incineration
equipment and
services currently
available.
Chromiun recovery
process requires
further
development.
Process compatible
with solid waste
disposed in fill
area. Remedial
work greater than
5 years.
COMPLIANCE
WITH ARAR5
Compl ies with
ARARs.
Page 1.8b (8)
OVERALL
PROTECTION
Risk from direct
contact controlled
by excavation.
Risks to workers
assoc i Bted with
sludge excavation"
and residual
material from
incineration
process addressed
through heal th and ,"
safety protect Ion. '
Potential for'
future'groundwater
Irrpacts from
sludge eliminated.
Environmental
IrrpactB from
ponded water In
pit/lagoons
reduced.
Compensatory
wetland area to be
-------
ALTERNATIVE
G\.I-1: No Action
GIJ-2:
Institutional
Actions
COMPARATIVE
SHORT TERM
EFFECTIVENESS
Remaining risk
from arsenic If
groundwater Is
ingested.
Reduces risk from
ingesting
groundwater
through
i nst itut I onal
controls. No
engineering
controls to
actively remedlate
aquifer.
SUMMARY OF GROUND WATER REMEDIAL ALTERNATIVES
SACO TANNERY WASTE PITS SITE
SACO, MAINE
lONG TERM
EFFECTIVENESS AND
PERFORMANCE
Magnitude of
residual risk
would decrease
. with time through
natural
attenuation
processes.
Groundwater
monitoring would
effectively track
contaminant
migration but not
remedlate site
conditions.
REDUCTI ON OF
MOBILITY, TOXICITY
OR VOLUME
No reduction in
mobility,
toltlclty, or
volume of waste
through pump-and-
treat system, but
natural
attenuation
reduces
contaminant
concentrations
with time.
No reduction In
mobill ty,
toltlclty, or
volume of waste
through pump-and-
treat system, but
natural
attenuat I on
reduces
contaminant
concentrations
with time.
IMPLEMENT-
lli.!J.!!
Five-year review
necessary. Future
groundwater
remedial actions
possible depending
on rate of natural
attenuation.
Groundwater
monitoring easy to
implement. Long-
term monitoring
services
available. Five-
year review
necessary. Future
groundwater
remedial actions
possible depending
on rate of natural
attenuation.
COMPLIANCE
WITH ARARS
MCL Compliance
attained at site
boundar i es. On-
site
concentrations of
arsenic eltceed
MCLs In four
monitoring well
samples.
MCL Compl lance
attained at site
boundaries. On-
site
concentrations or
arsenic uceed
MCLs in four
moni toring well
samples. ACL's
established under
the selected
remedy, and
attained in four
on-site monitoring
wells.
Page I8h (9)
OVERALL
PROTECTION
No protection to
public health and
the environment.
MCL achieved
through natural
attenuation over
more than 20-500
years. .
Protection to
public health and
the envl ronment
provided depending
on the
effectiveness of
Ins t itut i onal
controls and
groundwater
mani toring. MCL
achieved through
natural
attenuation over
more than 20-500
-------
ALTERNATIVE
G\I- 3: PIII'p and
Treat by
Precipitation/
Flocculation/
Clarification
SHORT TERM
EFFECTIVENESS
Reduces risk from
ingesting
groundwater
through active
aquifer ~ing.
PlII'ping time of
about 2 years
would be required
to reach MCL for
arsenic ~er
assuned
conditions.
LONG TERM
EFFECTIVENESS AND
PERFORMANCE
MCL for arsenic
would be achieved
aft~r ~ing, if
a ~ and treat
system could be
successful I y
designed.
Gr~water
monitoring would
verify
effectiveness of
extraction system.
REDUCTION OF
MOBILITY, TOXICITY
OR VOLUME
Groundwater
remediation by
active ~-and-
treat system
reduces
contaminant
mobil ity.
Precipitat ion/
flocculation/
clarification
scheme generates
sludge requiring
appropriate
di sposal.
IMPLEMENT-
!!WJl!
Extensive
extraction welt
network required
to ~
groundwater.
Piping system
would need to
prevent freezing
effccts.
Precipitation/floc
cuI at ion/
clarification
process readi I y
irrplementable.
Howcver, because
of the absence of
a defined source
area, a ~ and
treat system would
be difficult to
design and
irrplement. In
addition, the
presence of other
constituents
(iron, manganese)
signi f Icant! y
irrpacts chemical
doses and
treatment costs.
CIJ1PLIANCE
IIITH ARARS
Corrplies with
federal and state
ARARs for
grOU1dwater
protection.
Page 18b (10)
OVERALL
PROTECTION
Risk to hunan
health and the
environnent
reduced over a
period of 2 to 5
years depending 00
the success of
gr~water
extraction and
-------
ROD.DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 19-
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 7-3 in the
Feasibility study.
ESTIMATED TOTAL COST (Present Worth):
site reviews)
$57,000 (cost for 5 year
SC-2
Institutional Action
This alternative would consist of constructing a fence
around the site, posting warning signs, and restricting
access and future site use. This alternative would not
.provide adequate protection of human health and the
environment.
site
'A detailed tabular assessment of this alternative according
.to the evaluation criteria can be found on Table 7-5 in the
Feasibility Study.
ESTIMATED
ESTIMATED
ESTIMATED
ESTIMATED
TIME FOR CONSTRUCTION: 1 to 3 months
CAPITAL COST: $252,500
o & M COST (Present Worth): $303,000
TOTAL COST (Present Worth): $555,500
SC-3
Cover System
This alternative consists of covering the waste pits and
lagoons with soil. This alternative would reduce potential
risks to public health and the environment posed by
contacting or ingesting sludge. However, in comparison to
the selected remedy, it would not provide long-term
"effectiveness because it does not include strict, permanent
controls over future site development in the form of a
legislatively-created conservation area.. Additionally, this
alternative would not directly address the potential for
~ future. leaching of contaminants from the sludge into the
.. groundwater as provided in the selected remedy, which
- ~requires the establishment of a monitoring network to
monitor for releases of chromium and selection of a source
area treatment alternative in the event chromium is detected
to be leaching at significant levels.
ESTIMATED
ESTIMATED
ESTIMATED
ESTIMATED
TIME FOR CONSTRUCTION: 1 to
CAPITAL COST: $5,841,000
o & M COST (Present Worth):
TOTAL COST (Present Worth):
2 years
$188,500
-------
ROD' DECISION SUMMARY. '.
SACO TANNERY WASTE PITS SITE
Paqe 20
SC-3A
Cover System with Monitorinq Network and Institutional Controls
This alternative is the selected source control remedy and is
discussed in Section X, THE SELECTED REMEDY.
,SC-4
In-Situ Solidification/Stabilization
Contaminated sludge in each waste pit and lagoon would be
solidified using a backhoe or injection system to add
solidifying reagents. Solidified areas would then be
covered with soil to protect from freeze-thaw effects, and
revegetated. Excavation of sludge would not be required.
Based on field tests, EPA has serious reservations about how
,effectively and reliably the sludges at the site could be
,solidified in place. Given the pasty nature of the sludge,
intimate in-situ reagent mixing would be difficult.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 7-14 in the
Feasibility study.
ESTIMATED
ESTIMATED
ESTIMATED
ESTIMATED
TIME FOR CONSTRUCTION: 1 to
CAPITAL COST: $14,893,000
o & M COST (Present Worth):
TOTAL COST (Present Worth):
2 years
$188,SOO
$lS,081,SOO
sc-S
Excavation/Solidification/On-site RCRA Landfill
This alternative will be implemented in the event an
adequate'state statute, converting the site property into a
permanent conservation area, is not enacted within two years
from the date the ROD is signed. Refer to Section XIII for
a discussion of this alternative.
SC-6 "'.
Excavation/Solidification/On-site DisDosal
!~~-
,~ '-
This alternative is similar to SC-S, in that sludge would be
excavated and treated on site by solidification. However,
unlike SC-S, this alternative would not involve the
construction of a RCRA hazardous waste landfill. Treated
material would be consolidated and placed in a 9.S acre
disposal area on site. Fill material would be added to the
base of the disposal area to increase the vertical distance
between solidified material and the high water table. No
-------
ROD DECISION S~Y.
SACO TANNERY WASTE PITS SITE
Paqe 21
area would be capped with soils to enhance runoff 'and
minimize infiltration, but synthetic liners would not be
used.
This alternative would reduce risks to public health and the
environment from exposure to site contaminants. However,
this alternative would not attain ARARs. The relevant and
appropriate RCRA standards for landfills, which require two
or more liners and leachate collection systems, would not be
met.
In addition, this alternative could present future risks if
the solidification process proved to be inadequate over
time. There exists little information on the long-term
physical durability and chemical stability of
solidification/ stabilization. The fate of organic
chemicals in the sludge after solidification is uncertain,
:and without the additional protection against contaminants
leaching into the groundwater provided by the construction
. of the RCRA landfill, contaminants could potentially leach
into the groundwater over time. Finally, the cost of this
alternative is not substantially less than the cost of
Alternative SC-5, which was rejected by the State following
the issuance of the first Proposed Plan in part for reasons
of cost-effectiveness.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 7-21 in the
Feasibility study.
ESTIMATED
ESTIMATED
ESTIMATED
ESTIMATED
TIME FOR CONSTRUCTION: 3 to
CAPITAL COST: $26,946,000
o & M COST (Present Worth):
TOTAL COST (Present Worth):
4 years
$752,000
$27,698,000
SC-7
Excavation/On-Site RCRA Landfill
This alternative would involve excavating and disposing of
. sludge in an on-site RCRA hazardous ,waste landfill. . No
waste treatment would be performed prior to landfilling.
However, the landfill would include synthetic liners and
leachate collection systems to minimize potential
groundwater contamination. Because of the soft, pasty, low-
strength nature of the sludge, special landfilling
techniques or bulking agents may be required to provide
adequate stability of the landfill. Primary consolidation
and the leachate generated from the primary consolidation
would impact the construction schedules, construction
-------
ROD DECISION SUMMARY
SACO TANNERY' WASTE PITS' SITE
Paqe 22-
This alternative would reduce risks to public health and the
environment but would not provide the additional protection
offered by combining .landfilling with a treatment technology
such as solidification. The primary uncertainty a~sociated
with land disposal of the untreated waste material is the
long-term structural integrity of the RCRA cap. Finally,
the cost of this alternative is not substantially less than
the cost of Alternative SC-5, which was rejected by the
state following the issuance of the first Proposed Plan in
pa+t for reasons of cost-effectiveness.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 7-24 in the
Feasibility study.
ESTIMATED
ESTIMATED
ESTIMATED
ESTIMATED
TIME FOR CONSTRUCTION: 3 to
CAPITAL COST: $24,146,000
o & M COST (Present Worth):
TOTAL COST (Present Worth):
4 years
$4,903,000
$29,049,000
SC-9
Excavation/Soil-Washinq
This alternative would involve processing excavated soils
through a series of reaction chambers containing chemical
solvents to strip contaminants from the sludge. Aqueous
treatment systems would be required to treat and recycle the
washing fluids and the extracted contaminants. Chromium in
the sludge could potentially be concentrated for recovery
and recycling. Treated sludge would be backfilled on-site.
Alternative SC-9 provides treatment to extract contaminants
and offers potential for resource recovery of chromium.
However, the soil washing process is complex and would
require substantial waste handling and treatment of aqueous
residuals. Under ideal performance conditions, a reduction
in the volume of contaminated material would be achieved.
The soil-washing process has not been well demonstrated for
. sludge treatment such as the treatment required at this
site. In order to demonstrate the effectiveness of soil-
washing, extensive and costly development and testing prior
to full-scale implementation would be required.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 7-26 in the
Feasibility Study.
ESTIMATED TIME FOR CONSTRUCTION: 6 to 10 years
-------
ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 23
ESTIMATED 0 & M COST (Present Worth):
ESTIMATED TOTAL COST (Present Worth) :
$96,000
$107,548,000
SC-10
Excavation/On-site Incineration
Under this alternative, sludges would be excavated from the
pits and lagoons and transported to an on-site incinerator
for thermal treatment. The extremely high temperature in
the incinerator would destroy an estimated 99.99% of the
VOCs in the sludge. The exhaust gases from the facility's
combustion chambers would be passed through air pollution
control devices before being released into the atmosphere.
Residual ash material from the incineration operations would
require further management. The substantial quantity of
chromium in the ash could potentially be extracted using
acids in a controlled leaching process; this option offers
.'potential for resource recovery of the chromium.
Alternatively, the ash material could be solidified with
pozzolanic reagents and placed in an on-site RCRA landfill.
Incineration would be protective of public health and the
environment, and would reduce the volume of the waste.
However, contaminant mobility and toxicity may be increased
by the oxidation of chromium during thermal treatment. On-
site incineration services are available, but a chromium
recovery process would need to be developed. Attempts to
develop a chromium recovery process during the FS were
somewhat successful, but further process development would
be necessary to implement the technology for this site.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 7-33 in the
Feasibility study.
ESTIMATED TIME FOR CONSTRUCTION: 5 to
ESTIMATED CAPITAL COST: $92,822,000
ESTIMATED 0 & M COST (Present Worth):
ESTIMATED TOTAL COST (Present Worth):
7 years
$83,000
$92,905,000
B. ~
Groundwater (GW) Alternatives Analyzed
Groundwater alternatives address contaminants that have migrated
from the original source of contamination. At the STWP site,
there has been limited movement of contaminants from the waste
material contained in the waste pits and lagoons. Under current
conditions, on-site groundwater is not moving off site, but
discharging to the stream or wet area on the western portion of
the site. The groundwater alternatives evaluated for the site
-------
ROD, DECISION SUMMARY -
SACO TANNERY WASTE PITS SITE
Paqe 24-
extraction and treatment by precipitation/flocculation/-
clarification (GW-3).
GW-l
No Action
As with the no-action alternative for source control, the
no-action groundwater alternative is included to serve as a
basis for comparison with the other groundwater treatment
alternatives considered. The no-action alternative would be
selected only if the Site posed little or no risk to public
health and the environment.
The no-action groundwater alternative for the Saco Tannery
Waste Pits site would not be protective of public health and
the environment because on-site contaminant levels for
arsenic exceed health-based levels. Without adequate
.monitoring and institutional controls, or treatment, the no-
'action alternative would not reduce the risk posed by
ingestion of contaminated groundwater.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 8-11 in the
Feasibility Study.
ESTIMATED TOTAL COST (Present Worth):
site reviews)
$57,000 (cost for 5 year
GW-2
Groundwater Monitorinq and Institutional Action
This alternative is the selected groundwater remedy and is
discussed in section X, THE SELECTED REMEDY.
GW-3
Extraction 'and Treatment bv
PreciDitation/Flocculation/Clarification
, This alternative would involve installing extractio~ wells
to pump groundwater from contaminated areas to a
precipitation/flocculation/clarification unit. The treatment
process would remove arsenic from the water and the treated
water would be discharged to the stream on site. Sludge
produced from groundwater treatment would be thickened,
dewatered, and temporarily stored for off-site disposal.
This alternative would be protective of public health after
the contaminated groundwater is removed. However, several
potential problems with designing and implementing an
-------
ROD. DECISION SUMMARY.
SACO TANNERY. WASTE PITS SITE
Paqe 25'
of the diffuse nature of the arsenic concentration- in the
groundwater and the absence of a defined source. Since
extraction wells are likely to draw both clean and
contaminated groundwater, the influent to the
precipitation/flocculation/clarification unit may achieve
MCLs without treatment. Additionally, extraction of
groundwater may affect the hydrologic function of some of
the wetlands by altering groundwater recharge and discharge
characteristics. Such an alteration could be harmful to
aquatic and terrestrial fauna, destroying important food and
habitat resources. The extraction and treatment alternative
would reduce contaminant mobility, but generate sludge
requiring appropriate disposal.
A detailed tabular assessment of this alternative according
to the evaluation criteria can be found on Table 8-19 in the
,Feasibility Study.
ESTIMATED TIME FOR CONSTRUCTION: 2 to 10 years depending on
extraction system employed
ESTIMATED CAPITAL COST: $1,571,000
ESTIMATED 0 & M COST (Present Worth): $466,000 to $1,756,000
ESTIMATED TOTAL COST (Present Worth): $2 to $3.3 million
depending on the extraction system employed
x.
THE SELECTED REMEDY
The selected remedy includes both a source control (SC-3A) and a
groundwater component (GW-2) to achieve a comprehensive approach
for site remediation. Detailed conceptual discussions of the
source control and groundwater component can be found in the FS
Addendum and sections 8.3.2 of the Feasibility Study,
respectively.
For a discussion of the alternate remedy, see section XIII. The
alternate remedy will be effective if adequate legislation
converting the Site-property into a permanent conservation area
is not enacted within two years of signing of this Record of
Decision.
A.
Description of the Selected Remedy
1.
Source Control
a.
Remedial Action Objectives
The source control portion of the remedial action consists of
covering all of the waste pits and lagoons, the Chromium Lagoon 2
-------
ROD. DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 26
enacting legislatively-created institutional controls .to restrict
future use of the site. This approach is designed to minimize
exposure by human and environmental receptors to site
contaminants, which is one of the remedial action objectives
selected for the Site. In addition, the implementation. of a
groundwater monitoring program to monitor releases of chromium
from the sludge, along with a contingency for future action, is
-designed to address the remedial action objective of reducing the
threat that chromium will leach from the waste to the groundwater
in the future.
b.
Target Cleanup Levels
Results from the remedial investigation and risk assessments were
used to develop target cleanup levels for contaminated media.
Target cleanup -levels for chromium were first developed in the
remedial investigation. In the attached Technical Memos (see
Appendix C), target cleanup levels for chromium were subject to
further evaluation and target cleanup levels for lead, antimony,
and arsenic were developed. Preliminary target levels were
developed for contaminants of concern that showed carcinogenic
risk exceeding 10-7 or noncarcinogenic risk greater than a total
Hazard Index of 1.0. The Technical Memos also discuss the
methodology and assumptions used to develop the target levels.
For chromium, target levels were developed both for environmental
protection and protection of human health. The health based
target levels for chromium of 75,000 ppm (Cr III) and 375 ppm (Cr
VI) were developed. Assuming a maximum percentage of 4.4% Cr VI
to total Cr (see footnote number one), the corresponding total
chromium target level for Cr VI would be 8,523 ppm. The
environment based target level for total chromium of 2,000 ppm
was established through the Ecological Risk Assessment (Section
10.3 of th~ Phase II Remedial Investigation Rep~rt). The more
conservative environment based target level for total Cr (i.e.,
2,000 ppm) will be used as the target level to provide protection
of both human health and the environment.
. -
For lead, ~PA developed a health-based target ~~vel of 275 ppm.
The DEP (i'n consultation with t~e Maine Department of Human
Services '- 'DijS), requested a more stringent targe~ level of 125
ppm due to different assessments of lead toxicity. Specifically,
in contrast to EPA's assumptions, DHS assumed that the toxic
effects of lead do not require exposure for over a year's time
period to manifest themselves in some segments of the population.
EPA has set the target level for lead at 125 ppm as protective of
human health to satisfy the concerns of DEP and in consideration
of the relatively small cost increase associated with the more
stringent lead cleanup level.
-------
ROD" DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 27
The following are the cleanup target levels for sludge ~nd
sediment to be used for the Saco Tannery Waste pits site:
Lead:
Antimony:
Total Chromium:
Arsenic:
125 ppm
30 ppm
2,000 fpm
60 ppm
These target levels will be used to determine the extent of the
soil cover at the two areas of the Site where soil and sludge
contamination is not confined to the waste pits and lagoons.
c.
Areas requiring remediation
EPA has determined that all of the waste pits and lagoons at the
Site require remediation. This determination is based on a
review of sampling data, visual observations during field
activities, health and environment based target levels, and
contaminant transport considerations. In addition, EPA has
determined that the soil cover can be installed over each pit and
lagoon, generally without further sampling of contaminant
locations, because soil and sludge contamination appears confined
to the waste pits and lagoons. Further sampling, however, will
be necessary prior to installation of the soil cover in the areas
of sediment contamination found at the Site near Waste Pit 9 and
in the seep area near Chromium Lagoon 2.
Some of the information that EPA considered in deciding to
remediate all of the waste pits and lagoons, and to install the
soil cover over the waste pits and lagoons generally without
further sampling, is provided below:
*
The chemical and physical nature of sludge does not
differ among waste pits. Therefore, the remedial
3 The average concentration of arsenic in soil/waste at
the STWP site is 8.9 ppm. The maximum level of arsenic detected
in sediment outside of contaminated areas from surface water
drainages at the ~STWP site is 31 ppm. .Since the arsenic is not
associated with. the waste sludges and may be an artifact of
former pesticide use at the site or may be naturally occurring, a
concentration of 60 ppm, which falls within the carcinogenic risk
range of 10-4 to 10-5, will be used as the target level for
arsenic in contaminated sediment. In other words, EPA has
selected a target level for arsenic which does not pose an
unacceptable risk and which is close to background levels for
arsenic found at the site. Using this standard, EPA will not
-------
ROD DECISION SUMMARY,.
SACO TANNERY WASTE PITS SITE
Paqe 28
action should address contamination in all waste pits
or lagoons rather than particular waste pits.
*
Dense sludge layers generally ranging from two (2) to
six (6) feet exist in waste pits and lagoons.- Soil
contamination appears restricted to the highly
contaminated waste sludge. Significant contamination
was not detected below the waste sludge or outside
chromium lagoons and waste pits with sand berms.
*
contaminated sludge is likely to be relatively easy to
identify because it is generally limited to the
confines of waste pits and lagoons, and has not
migrated. The dense, black, pasty nature of the sludge
clearly distinguishes it from surrounding and
underlying native soils. It is anticipated that the
interface between contaminated sludge and clean soil is
distinct. It should therefore be technically feasible
to distinguish between contaminated sludge and clean
soil during installation of the cover system.
As stated above, two areas of the site will undergo further
investigation prior to installation of the cover system. Two on-
site locations contain elevated levels of contaminated sediment.
First, sediments collected from the wet area near Waste pit 9
contain significant concentrations of chromium and lead. As
stated in the Phase II RI report, Waste Pit 9 appears to be the
source of chromium and lead in the wet area west and north of the
pit. Using analytical data and field observations, this area of
contamination appears to be approximately 29,000 square feet. A
sampling program will be implemented to further delineate the
extent of area to be covered. This area will be covered to meet
the target levels established in preceding section.'
Second, a sediment sample taken from the seep area adjacent to
Chromium Lagoon 2 detected the highest arsenic concentration at
the Site. Before arsenic contaminated sediment is covered, the
Chromium Lagoon 2 seep area will be sampled to identify the
extent of arsenic contamination. This area will then be covered '.
to meet the target levels established in preceding section.
2;
Groundwater
4 It is anticipated that the elevated concentrations of
chromium and lead detected in surface water draining from this
area will attenuate once the source area has been covered. If
levels continue to exceed AWQC after the cover system has been
established, the need for additional remedial measures will be
-------
ROD DECISION SUMMARY', .
SACO TANNERY WASTE PITS SITE
Paqe 29
a.
Remedial Action Objectives
The groundwater portion of the remedial action involves
restricting the use of groundwater at the Site, and implementing
a water quality monitoring program to observe the distribution,
migration, and attenuation of contaminant concentrations over
time. Under the water quality monitoring program, further
evaluation of the site will be conducted if contaminants exceed
specified action levels. The groundwater portion of the remedial
action is designed to prevent ingestion of contaminated
groundwater. The only contaminant detected in on-site
groundwater at levels in excess of its MCL is arsenic.
Currently, on-site groundwater is not used as a drinking water
source. In addition, on-site groundwater contamination has not
moveq to off site residential well locations, and groundwater at
the Site is not affecting the quality of surface water as the
groundwater discharges to the surface. The institutional
controls, monitoring program, and contingency for further
evaluation of the Site will assure that the objective of
preventing ingestion of contaminated groundwater continues to be
maintained.
In addition, on-site groundwater contamination is expected to
dissipate as natural attenuation dilutes and disperses the
contaminants. However, the natural attenuation process may not
result in substantial reduction in contaminants for many years in
the future. Through the water quality monitoring program, EPA
will observe the distribution, migration, and reduction of
contaminant concentrations over time.
b.
Action Levels
Action levels have been established for use in the
groundwater/surface water monitoring program required by the
selected remedy. Exceedances of these action levels will result
in~further evaluation of the remedial action.
,First, Safe Drinking Water Act Maximum contaminants Levels (MCLs)
are relevant and appropriate groundwater standards at the site.
These standards will be used in monitoring the levels of
groundwater contaminants for all contaminants, other than
arsenic, for which a ACL has been established.
Second, with respect to arsenic, EPA is setting Alternate
Concentration Limits (ACLs). The ACLs for arsenic will be set at
the currently observed maximum arsenic levels detected in four
on-site monitoring wells, as follows: MW 103 (123 ppb), MW 114B
-------
ROD.DECISION,SUMMAR~
SACO TANNERY WASTE PITS,SITE
Paqe 30
arsenic in these four on-site wells will be monitored-to
determine whether the ACLs for arsenic continue to be met in the
future. Further, the levels of arsenic detected in monitoring
wells located at the site boundary will be monitored to assure
that arsenic at levels in excess of the MCL for arsenic. are not
migrating off-site. EPA has set ACLs for arsenic in four
monitoring wells at the STWP site in accordance with CERCLA ~121
~d) (2) (B) (ii), as discussed in section X.C.2.c of this ROD.
Third, with respect to surface water monitoring, EPA will monitor
on-site'streams to determine whether federal Ambient Water
Quality criteria (AWQC) are exceeded.
B.
Description of Remedial Components
site 'Preparation: site preparation will include clearing and,
grubbing to prepare the Site for remedial activities. See Figure
7-1 in the Feasibility Study for a conceptual site layout for
remediation. Before remedial construction begins on-site, a
fence will be installed around the construction area to deter
vandalism and minimize public exposures to construction
activities during remedial activities. Warning signs will be
posted along the fence and at the entrance gate. The current
lock at the entrance gate will be inspected to insure its
integrity and will be replaced if it is in deteriorating
condition. Roadways will be designed and constructed to minimize
environmental impact while providing adequate access for
construction equipment.
Remove Ponded Water from Pits and Lagoons and Treat at Off-site
Facilitv: Ponded water will be pumped from each waste pit and
lagoon and transported off site for treatment at a commercial
water treatment facility, or, alternatively, at a local POTW.
This process. will occur on a pit by pit basis as the pits are
covered.
Install Bio-intrusion Barriers: A geotextile fabric will be
installed to cover ~he waste sludges in the pits .and lagoons and
provide forra-stable surface for the placement of ,the rock,
gravel and.s~il layers. A one-foot thick rock anq a six to eight
(6 to 8) inch thick gravel layer may be installed 'to inhibit the
disturbance of the waste sludges by burrowing animals. During
remedial design the need for the rock and gravel layers will be
evaluated on a pit by pit basis. Burrowing animals will not
disturb wastes situated below the water table. Thus, an
evaluation of the need for a rock and gravel layer in a
particular pit will include consideration of the depth of the
water table and whether the installation of a groundwater
extraction and treatment system, in the future might affect the
-------
ROD DECISION SUMMARY"
SACO TANNERY WASTE PITS SITE
Page 31
rock and gravel layer will depend on whether the use of- an
alkaline rock layer throughout the cover system is determined to
be necessary during remedial design. The use of alkaline rocks
might affect the pH of groundwater percolating through the wastes
and possibly reduce the potential for chromium leaching. In any
event, if a rock layer is installed, rock sizes of five (5)
inches or greater will be used since the burrowing animals are
not likely to move objects greater than themselves.
Cover Waste pits and Laqoons: The cover system for each pit will
consist of a minimum of two (2) feet of till material (three [3]
feet of till material if rock and gravel layer is not
incorporated) and a minimum of 18 inches of a vegetative loam
material. Figure 4 illustrates a cover system cross section of a
typical pit. The till layer will likely consist of a variety of
silts, sands, and some clays. The amount of fines (ASTM D 422
Specification for sieve analysis) will be approximately 20 to 50
percent. This soil makeup will enable the material to hold some
moisture and help enhance growth in the overlying vegetative loam
material. The till material will also minimize the potential for
erosion. The vegetative loam cover (18 inches) will seek to re-
establish typical vegetation found in a wooded environment like
the STWP site. Standard unscreened loam will be used for the top
layer in the cover system. Both till and loam will be supplied
from an off-site source. However, whenever practicable, site
remediation activities requiring the excavation of soils will be
timed so that recovered on-site till and loam can be used as part
of the cover system. To promote runoff at each waste pit
location, the cover will be sloped no less than three (3)
percent. The thickness of the cover system must be adequate to
develop and maintain a higher elevation than the surrounding
ground surface, taking into account the expected consolidation of
sludges under the cover material. Prior to placement of the
, cover material, large vegetative growth (e.g., trees) will, be
removed from inner pit areas. This clearing will occur during
site preparation work. In addition, existing berms surrounding
the pits will be cut down if their present elevations exceed the
anticipated final cover system elevation. 'During remedial.
design, the use c~ one ,large cover for pit clusters instead of
multiple covers'will be evaluated where feasible to avoid
potential drainage and erosion problems between covers.
Chromium Lagoons 1 and 2 will be covered using these same
procedures. As with the pits, the need for the rock and gravel
layer in Chromium Lagoons 1 and 2 and the Chromium Lagoon 2 fill
area will be evaluated during design. Because the lagoons are
significantly larger and deeper than the pits, more cover
material will be necessary to fill and cover these areas. The
soil sys~em for both lagoons, as illustrated in Figures 5 and 6,
-------
EXCAVATE BERM AND PUSH
INTO PIT
18" LOAM
SLOPE ~ 3%
SLUDGE
-6"GRAVEL LAYER
Pap,e 31 n
PROPOSED COVER SYSTEM
SLOPE ~ 3%
,
~
'-NATIVE SOIL
WASTE PIT CROSS SECTION
NOT TO SCALE
WASTE PIT COVER SYSTEM
SACO TANNERY WASTE PITS SITE SACO, MAINE
~
\ EXISTING. GROUND
EXISTING BERM
-------
EXCAVATE BERM AND
PUSH INTO PIT
Paee ~ 1 h
SLOPE) 3%
18" LOAM
PROPOSED COVER SYSTEM
SLOPE ~ 3%
,
,'<
\
5' TILL
SLUDGE
NATIVE SOIL ~
I' ROCI< LAYER
EXCAVATED BERM MATERIAL
6" GRAVEl LAYER
LAGOON 1 CROSS SECTION
NOT TO SCALE
LAGOON 1 COVER SYSTEM
SACO TANNERY WASTE PITS SITE SACO, MAINE
r. ,
, ,"-
.. .""i.'-':;-
--.I
EXISTING GROUND
EXISTING BERM
FIGURE
-------
[
LAGOON PERIMETER
SOLID WASTE AREA
2' TILL
CHROMIU~ LAGOON 2
NOT TO SCALE
Page 31c
EXCAVATE BERM AND PUSH INTO PIT
010 .> 3~
'!> 0 IB-LOAM
7 ,
~ ".1:.",
-~~ .. " .. '10~:
. ~ ~ .
~ SOlID WASTE ~ 5'~ " ,: .
MATERIAL ---
SLUDGE --1 EXISTING GROUND
E~~'NG BERM . J ~XCAVATED IlERM MATER~AL
NATIVE SOIL LEXIST~:" COVER I ROCK LAYER
6 .. GRAVEL LAYER
LAGOON 2 CROSS SECTION A-AI
NOT TO SCALE
LAGOON 2 COVER SYSTEM
SACO TANNERY WASTE PITS SITE SACO, MAINE
FIGURE
-------
ROD DECISION SUMMARY"
SACO TANNERY WASTE PITS SITE
Paqe 32
one' and one-half [1.5] foot rock and gravel layer) and a minimum
of one and one-half (1.5) feet of vegetative loam. Cover
material will be graded and sloped (i.e., greater than or equal
to three [3] percent) to promote runoff. Existing berms will be
cut if their present elevations exceed the anticipated final
,cover system elevation.
The solid waste area located in the southwestern corner of
Chromium Lagoon 2 will be covered with two (2) feet of till
materia~ and 1.5 feet of loam (overlying the rock and gravel if
needed, and geotextile). Existing berms around the solid waste
area will not be moved or cut. The solid waste area will also be
graded and sloped (see Figure 6).
Coverinq Wet Area and Seep Sediments: An estimated 29,000
square foot (based on analytical data and field observations) wet
area near Waste Pit 9 contains contaminated sediments. To
prot~ct public health and the environment from potential
exposure, this area will be covered with approximately two (2)
feet of till and one and one-half (1.5) feet of vegetative loam
overlying the geotextile fabric or the rock and gravel layer.
Grading and sloping will be similar to the pit covering process.
Finally, the seep area along the outer perimeter of Chromium
Lagoon 2 (near the western berm) will be covered. This area
consists of surface leachate believed to be seeping from Chromium
Lagoon 2. The estimated 7,000 square foot seep area will be
covered with a one (1) foot layer of rock and six to eight (6 to
8) inches of gravel (if a rock and gravel layer is determined to
be necessary), two (2) feet of till, and one and one-half (1.5)
feet of vegetative loam. Following installation of the soil
cover, the seep area will be graded and sloped to promote runoff.
The exact extent of the wet area and seep sediments to be covered
will be determined during design. A sampling program will be
undertaken'to further delineate the area of' contamination. The
area will be covered to meet target levels established in section
X.A.1.b.
SurVey Final Cover Contours and Install-Permanent Markers: The
location of the final cover contours will be surveyed and,
permanent markers installed for easier location in the future.
Additional markers will be located at various locations on-site.
These markers will include warning language to provide notice to
the public that hazardous substances are buried below the soil
cover.
Re-establish Veqetation at Covered and Disturbed Areas: A
variety of seeding and planting procedures may be used t~ re-
-------
ROD DECISION' SUMMARY' '. .
SACO TANNERY WASTE PITS SITE
Paqe 33
cover system is installed. Vegetative loam cover soils would
support several types of vegetation. Presently, wetlands and
upland areas at the site provide habitats that can support
diverse wildlife populations. Given the size of the Site and its
heavily forested nature, it is likely that much of the Site will
revegetate itself over a period of several years after
remediation. A meadow grass such as crown vetch or reed canary
grass will be applied to begin the revegetation process.
However, seeds and nuts from present plant species will gradually
re-establish natural vegetation in covered areas. In addition to
the covered areas, stockpiling areas, equipment storage areas,
and vehicle turnaround areas will be revegetated following
remediation to prevent further erosion and restore natural
habitats.
Create Compensatorv Wetlands Area On-Site: A minimum of about
5.85 acres of wetlands may be lost as a result of source control
remedial activities at the Site. Additional areas may also be
lost during site preparation work or during clearing for
pit/lagoon access. Given the levels of contaminated wastes
disposed of at the Site, there is no practicable alternative to
covering the waste pits and lagoons that would have a lesser
impact on the wetlands. Unavoidable impacts on the wetland areas
would be mitigated to the maximum extent possible using silt
curtains, hay bales and check dams. In order to compensate for
wetlands lost, wetlands of equal or higher value will be
recreated, to the extent required by the federal and state
wetlands ARARs. In siting and developing compensatory wetlands,
EPA will consider potential effects on groundwater flow or
adverse impacts on other aspects of the remedial actions. In
order to re-create wetlands of equal or higher value, the
functional attributes of the wetlands presently on site will be
further evalua~ed during remedial design. The Baseline Wetlands
Assessment and the Ecological Risk Assessment provide some of the
necessary ~nformation to evaluate the functional attributes of
the STWP wetlands.. Further evaluation is required concerning the
following functiona~ attributes of the wetlands: hydrologic
functions, water quality functions, habitat functions, ecosystem
functions, and', socioeconomic functions. A yearly Operation and
maintenance program to be developed during remedial~design will
be required for several years after construction of wetland
areas. Additionally, a monitoring program to be developed during
remedial design will be required to evaluate the wetland sediment
and water quality and the success of the wetland in meeting the
hydrological, biological and cultural functions necessary for the
STWP site. section 7.2.3 of the Feasibility Study includes a
discussion on establishing compensatory wetlands.
Post-Closure Maintenance: Post-closure maintenance will be
-------
ROD'DECISION- SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 34
to perform additional work or repairs on covered areas., For at
least the first five years following the installation of the
cover system, post-closur~ maintenance inspections will occur
twice a year. Maintenance activities may be required if cover
soils have been disturbed by burrowing animals or "off-road"
vehicles driven over the Site. Repairs may also be necessary to
support erosion control or to revegetate base areas. Additional
cover soils may be applied and graded during post-closure
maintenance.
Land Use Restrictions: The Site property will be designated as a
permanent state conservation area pursuant to an act of the Maine
state legislature. Under the state law, development of the site
for residential or commercial purposes will be permanently
prohibited. Excavations which penetrate the cover system
described above will be prohibited. The use of on-site
groundwater as drinking water and the installation of drinking
wate~ wells on-site will also be prohibited. State law, or state
regulations or agreements implementing the state law, will also
include provisions for future maintenance of the site property by
state officials, for the enforcement of the law by state
officials, and for the maintenance of permanent markers to
provide notice to the public of the location of the covered waste
pits and lagoons. In addition to a state law restricting the
: ~ture uses of the Site, deed restrictions will be instituted to
~~ovide additional assurance that the future development of the
Site will be permanently prohibited.
The State will enact the necessary law, including regulations or
agreements implementing the law, within two years of September
27, 1989, which is the execution date of this ROD by the Acting
Regional Administrator of U.S. EPA Region I. If the necessary
law, and regulations or agreements are not enacted, and in
effect, within two years of September 27, 1989, i.e., on
September 27, 1991, the alternate remedy described in Section
XIII of this ROD will be effective and will be implemented.
Similarly, if EPA determines that the necessary state law,
regulations, or agr~ements as enacted and in effect on September
27, 1991 are inadequate, the alternate remedy described in
s~ction XIII of. this ROD will be effective and will Qe~
implemented. 5
Performance of the remedial action will begin prior to september
27, 1991 if the necessary state law, regulations, and agreements
5 Although a state law converting the site into a
conservation area was recently passed, EPA is currently reviewing
the adequacy of the law. A copy of the state law is contained in
-------
ROD DECISION SUMMARY"
SACO TANNERY WASTE PITS SITE
Paqe 35
are in effect and deemed adequate prior to that date, and other
considerations do not del~y performance.
Desiqn and Install Monitoring Network: Monitoring wells will be
sited at and around the property boundary (including but not
.limited to MW 4 A,B) as well as within the interior of the Site.
Perform Monitorinq of Groundwater/Surface Water: The
groundwater/surface water monitoring program to be implemented at
the site will have five objectives and components.
1. Monitoring will be performed to detect releases of
chromium from the wastes to the groundwater. To monitor for
releases of chromium, groundwater quality samples will be
collected from the property boundary wells, and from selected
wells within the property boundary, and analyzed for chromium on
a qu&rterly basis.
2. Monitoring will be performed in four on-site monitoring
wells to assure that the ACLs for arsenic continue to be attained
in these wells. As stated above, the ACLS for arsenic will be
set at the currently observed maximum arsenic levels detected in
four on-site monitoring wells as follows, MW 103(123 ppb), MW
114(77 ppb), MW 111B (64 ppb), and MW 101 (70 ppb). These wells
will be sampled quarterly to assure that the ACL set in each of
these wells continues to be attained. In addition, a monitoring
program will be developed and implemented to confirm continuation
of conditions supporting an ACL demonstration, in accordance with
CERCLA ~121(d) (2) (B) (ii). This monitoring program may include an
evaluation of the seasonal variability in contaminant
concentrations, the geochemical conditions that may affect the
mobility of arsenic, and determination of arsenic speciation.
3. Monitoring will be performed in wells sited at and
around the property boundary and within the interior of the site
to monitor the levels, distribution, and migration of arsenic,
and other selected target compounds. To monitor the levels and
movement of these contaminants, selected monitoring wells will be
sampled quarterly for selected target compounds6 (including but
not limited to arsenic, lead, manganese, chlorobenzene and bis[2-
ethylhexyl]phthalate), and annually for Target Compound List
6 The selected target compounds to be monitored in the
groundwater will include the contaminants of concern identified
for groundwater at the STWP site. contaminants of concern were
selected based on toxicity, level of contamination, mobility, and
persistence in the environment. For groundwater these are:
arsenic, lead, manganese, chlorobenzene, and bis(2-ethylhexyl)
-------
ROD DECISION SUMMARY..
SACO TANNERY WASTE PITS SITE
Paqe 36
metals, VOCs and SVOCs. .
4. Surface water monitoring in on-site streams will be
performed. Surface water and sediment samples will be collected
from selected on-site stream locations twice a year, during low
and high flow seasons, and analyzed for selected target compounds
. (including but not limited to arsenic, chromium, lead, manganese,
chlorobenzene and bis[2-ethyl-hexyl]phthalate) .
5. Monitoring will also be performed in off-site
residential wells. A residential well sampling program will be
instituted with the objective of collecting periodic samples for
Target Compound List metals, VOCs and SVOCs from existing and new
residential wells in use along Hearn and Flag Pond Roads within
the area shown on Figure 7. Additionally, if new residential
wells are installed along Hearn and Flag Pond Roads, water-level
data will be collected to monitor for possible changes in on-site
groundwater flow patterns (as it affects contaminant
distribution). The water level monitoring program will be
. accomplished through the periodic use of continuous recorders on
selected monitoring wells during seasonal low water periods.
The sampling and monitoring programs presented above will be
conducted for at least three years beyond the completion of
construction phase of the remedial action. At that time, the
frequency and list of analytes monitored in the groundwater and
surface water will be evaluated and possibly reduced, in
accordance with relevant and appropriate RCRA groundwater
monitoring standards. Subsequent to the initial reassessment,
the duration and scope of monitoring activities will be
reassessed periodically based on sampling results and observed
trends. At a minimum these reassessments will occur during each
five-year site review described below. If the water level
monitoring program is instituted, ~nd residential well use is
subsequently reduced below current usage, the water level
monitoring program would be reevaluated and possibly
discontinued. Similarly, the residential well sampling program
will be reevaluated. and modified based on reductions of
residential well use.
. .prior to and during design and implementation of the selected or
alternate remedy, groundwater monitoring of selected monitoring
wells and residential wells located near the site will begin to
ensure that the current situation remains stable.
continqencies for Future Actions: An evaluation of the need for
an additional remedial action at the site will be performed in
-------
Page 36;
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-------
ROC" CECISION- SUMMARY. --
SACO TANNERY WASTE PITS SITE
Paqe 37
following action level exceedances7:
1. Further evaluatiQn of the site will be conducted if
concentrations of chromium and other contaminants, other than
arsenic, are detected at levels above MCLs in any of the
monitoring wells.
2. Further evaluation of the site will be conducted if
concentrations of arsenic are detected above the established ACLs
set for arsenic in MW 103, MW 114B, MW 111B, and MW 101, or if
conditions no longer support an ACL demonstration in accordance
with CERCLA ~121 (d) (2) (B) (ii) .
3. Further evaluation of the Site will be conducted if
concentrations of arsenic are detected above the MCLs for arsenic
in any of the wells sited at or around the property boundary.
,4. Further evaluation of the site will be conducted ~f
contaminant concentrations above AWQC are detected in on-site
identifiable streams because of discharge of site related
groundwater contaminants into surface water.
Curing any future evaluation of the Site, the need for a
groundwater extraction and treatment system, an alternate
drinking water supply, or other remedy will be reevaluated.
evaluation will account, to the extent feasible, for natural
seasonal fluctuations in groundwater quality affecting the
contaminant concentrations and for increases in contaminant
concentrations attributable to the short term impacts of
construction activities.
This
or
7 EPA will determine whether sampling results establish an
exceedance of any groundwater/surface water action level,in
accordance with the applicable or relevant and appropriate
standards for the site. For any contaminant for which no MCL,
ACL or AWQC exists, monitoring results shall be compared to
health-based levels"and interpreted in accordance with the EPA's
Supplemental Risk Assessment Guidance for the Superfund~Program
(June 1989) ("Risk ~ssessment Guidance"), or any relevant
guidances which may become effective in the future. The current
EPA Risk Assessment Guidance provides, in relevant part that:
When the [Hazard Index] exceeds one [1.0] for either a
single compound or several compounds exhibiting similar
toxic endpoints, then further discussion is needed
considering the nature of the relevant toxicity endpoint,
the quality of the toxicological database, and the magnitude
of the uncertainty factor used in the derivation of the
-------
ROD-DECISION SUKHAR~ .
SACO TANNERY WASTE PITS SITE
Paqe 38
In addition, if, in the future, based on the results of this
water quality monitoring, .levels of chromium at 500 ppb (i.e.,
levels ten times in excess of the MCL for chromium of 50 ppb) are
detected in any of the wells sited at or around the property
boundary, a source control remedial alternative that uses
~reatment technologies will be performed at the Site.
Conduct Five-Year site Review: Because this alternative would
result in contaminants remaining on-site, EPA will review the
Site at' least once every five years after the initiation of the
remedial action at the site to assure that the remedial action
continues to be protective of human health and the environment.
This review will be consistent with the CERCLA standards
applicable for five-year site reviews in effect at the time of
the review. If justified by the five-year review, remedial
actions, such as installation of a groundwater extraction and
trea~ment system, installation of an alternate water supply, or
treatment of the sludge may be evaluated, required, recommended
and/or implemented. EPA will also evaluate the risks posed by
the Site at the completion of the remedial action (i.e., before
the site is proposed for deletion from the NPL).
ESTIMATED
ESTIMATED
number of
ESTIMATED
depending
ESTIMATED
million
TIME FOR CONSTRUCTION: 1
CAPITAL COST: $6.6 to 6.8
wells
O&M COST (Present Worth):
on the number of wells
TOTAL COST (As presented in
to 2 years
million depending on the
$2.5 to 3.8 million
Table 8):
$9.2 to 10.6
[These costs represent the combined costs of Alternative SC-3A
and. GW-2.]
C.
Rationale for Selection
The rationale for choosing the selected alternative is based on
the assessment of e4ch criteria listed in the evaluation of
alternatives section of this document. In accordance with
section 121 of CERCLA, to be considered as a candidate for
selection in the ROD, the. alternative must have been found to be
protective of human health and the environment and able to attain
ARARs unless a waiver is invoked. In assessing the alternatives
that met these statutory requirements, EPA focused on the other
evaluation criteria, including, short term effectiveness, long-
term effectiveness, implementability, use of treatment to
permanently reduce the mobility, toxicity and volume, and cost.
EPA also considered nontechnical factors that affect the
implementability of a remedy, such as state and community
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Page 38a
. .
TABLE 8
COST ESTIMATE: ALTERNATIVE SC-3A
COVER SYSTEM WITH INSTITUTIONAL CONTROLS
SA CO TANNERY WASTE PITS SITE
SACO, MAINE
OPTION': EIGHT ADDITIONAL MONITORING WEllS
ACTIVITY £QiI TOTALS
I. CAPITAL COSTS
A. INITIATE LEGISLATION FOR
CONSERVATION AREA DESIGNATION
B. SITE PREPARATION (INCLUDING
SITE FENCE) $479,000
C. REMOVAL AND OFF-SITE TREA TMENT
OF PONDED WATER $363,000
D. INSTALLATION OF GEOTEXTILE $123,700
E. INSTALLATION OF ROCK & GRAVEL
FOR BIO-BARRIER $569,300
F. COVERING PITS, CHROMIUM LAGOONS
1 AND 2, AND WET AREA NEAR WASTE
PIT9 $1,440,800
G. INSTALL MONITORING WELLS $46,000
H. REVEGET ATE ALL COVERED AREAS AND
ADDITIONAL DISTURBED AREAS $26,500
I. WETLANDS RESTORATION $1,222,000
SUBTOTAL OF ITEMS A - I $4,270,300
J. HEALTH & SAFETY (@ 10%)
LEVEL D PROTECTION $427,000
K. LEGAL, ADMINISTRA TlON,
PERMITTING (@ 5%) $213,500
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Page 38a (.
, ~ . '.
TABLE 8 (Continued)
05T ESTIMATE: ALTERNATIVE SC-3A
COVER SYSTEM WITH INSTITUTIONAL CONTROLS
SA CO TANNERY WASTE PITS SITE
. SACO, MAINE
OPTION 1 (Continued)
ACTIVITY
COST
TOTALS
M.
SERVICES DURING CONSTRUCTION (@ 5%)
$213,500
SUBTOTAL OF ITEMS J - M
$1,281,000
SUBTOTAL
$5,551,300
CONTINGENCY (@ 20 %)
$1,110,300
TOTAL CAPITAL
$6,661,600
II. ANNUAL OPERATING COST (2-YEAR PERIOD DURING REMEDIAL ACTION)
A. SECURITY $5,1 OO/Y R
PRESENT WORTH OF ANNUAL OPERATING COSTS 59,500
III. POST-CLOSURE ANNUAL COSTS
A. ANNUAL INSPECTIONS (30 YEARS) $7,600/YR
B. MISCELLANEOUS LAND
SURFACE CARE (30 YEARS) $1 ,000/YR
C. SAMPLING & ANALYSIS
(QUARTERL Y, YEARS 0-2) $266,800/YR
(SEMI-ANNUALL Y, YEARS 2-30) $133,400/YR
PRESENT WORTH OF POST-CLOSURE ANNUAL COST 52,483.500
IV. FIVE-YEAR REVIEW (FOR 30 YEARS) $20,400/REVI EW
PRESENT WORTH OF FIVE- VEAR REVIEW 557.000
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Page 38a (
. . TABLE 8 (Continued)
. .!. '.COST ESTIMATE: ALTERNATIVE SC.3A
COVER SYSTEM WITH INSTITUTIONAL CONTROLS
SA CO TANNERY WASTE PITS SITE
SACO. MAINE
OPTION 2: SIXTEEN ADDITIONAL MONITORING WEllS
(REFER TO OPTION 1 FOR BREAKDOWN OF ACTIVITIES)
ACTIVITY TOTALS
I. TOTAL CAPITAL COSTS $6,725,600
II. ANNUAL OPERATING COSTS (PRESENT WORTH) $9,500
III. POST-CLOSURE ANNUAL COSTS (PRESENT WORTH) $3,154,700
IV. fiIVE-YEAR REVIEW COSTS (PRESENT WORTH) $57,000
NET PRESENT WORTH OF Al TERNA TlVE (OPTION 2) 59,946.800
OPTION 3: TWENTY-FOUR ADDITIONAL MONITORING WEllS
(REFER TO OPTION 1 FOR BREAKDOWN OF ACTIVITIES)
ACTIVITY TOTALS
I. TOTAL CAPITAL COSTS $6,792,600
II. ANNUAL OPERATING COSTS (PRESENT WORTH) $9,500
III. POST.CLOSURE ANNUAL 'COSTS (PRESENT WORTH) $3,692,300
IV. FIVE-YEAR REVIEW COSTS (PRESENT WORTH) $57,000
NET PRESENT WORTH OF ALTERNATIVE (OPTION 3) 510.551.400
-------
" '.
ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 39
statutory preferences of CERCLA, EPA selected the remedial
approach for this Site.
1.
Source Control
The range of source control alternatives considered for detailed
analysis at the STWP site included no action alternatives (SC-l
and SC-2) , alternatives that involved covering the soils and
sludges (SC-3 and SC-3A), alternatives that involved treatment of
the wastes (SC-4, SC-S, SC-6, and SC-7) , and alternatives that
involved resource recovery (SC-g and SC-IO). Of these
alternatives, two (SC-3A and SC-S) best satisfied EPA's remedial
selection criteria.
Initially, in the first Proposed Plan issued for the Site, EPA
proposed SC-S as the preferred alternative for the site. Under
Alte~native SC-S, described in Section XIII, the soils and
sludges from the waste pits and lagoons would be excavated,
consolidated, and solidified, and the solidified material would
be placed in a RCRA hazardous waste landfill to be constructed
on-site. Due to the large volume of wastes disposed of at the
Site, the excavation, treatment, and landfilling of the wastes
required by Alternative SC-S would be expensive. Alternative SC-
S has an estimated present worth cost of $33.8 million.
Following the issuance of the first Proposed Plan, DEP refused to
concur with the preferred alternative. DEP's stated objections
to the preferred alternative included its cost effectiveness in
addition to certain technical concerns.8 Because the STWP site
is a fund-lead site, the preferred alternative could not be
implemented without DEP's concurrence and its agreement to assist
in paying for the costs of the remedial action.
In view of DEP's comments, EPA reassessed the alternatives
considered in the Feasibility Study. Specifically, EPA amended
the cover alternative (SC-3) so that it included several
additional protective measures. The amended cover alternative
(SC-3A) involves the covering of soils and sludges with several
feet of layered soil and other materials. ' For additional
protection, SC-3A also requires the implementation of a
groundwater monitoring system, a contingency for treatment in the
event that significant levels of chromium migrate from the waste
in the future, and the enactment of a state law which will
convert the site into a state conservation area. Alternative SC-
3A was analyzed in detail in an addendum to the Feasibility
Study. The present worth cost of SC-3A is approximately $10
8 For a discuSS7.-1 of DEP's technical concerns, see the
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ROD DECISION S~~
SACO TANNERY WASTE. P. ~'S SITE
Paqe 40
miliion, substantially less than the cost of Alternative SC-5.
D
Alternative SC-3A, with ~ts additional safeguards, is protective
of human health and the environment. Assuming that chromium will
.not leach into the groundwater and migrate off-site in the
future, EPA concludes that this alternative is as protective of
human health and the environment as the originally proposed
. alternative, SC-5. Large volumes of waste were disposed of at
the STWP site in two waste lagoons and 53 disposal pits.
Disposal occurred during a period of about twenty years or more.
The surface area of the contamination is approximately 13 acres.
Significantly, although there was a large volume of wastes
disposed of at the Site over a long period of time, contamination
originating from the tannery wastes is mainly confined to the
waste pits and lagoons. Groundwater analyses indicate that
chromium is not migrating from the sludge under current
cond~tions, and has not migrated from the wastes in the many
years since disposal began. Other contaminants associated with
the sludge have been detected in the groundwater in low levels,
which further indicates the limited movement of the waste
material found at the site. Based on the absence of evidence of
significant levels of migration of the wastes, the installation
of a soil cover system over the pits and lagoons will effectively
protect human health and the environment.9
In addition, to address concerns that chromium may begin to
migrate from the soils and sludges in the future, Alternative SC-
3A includes a groundwater monitoring program and a contingency
for further evaluation and treatment in the event that
significant levels of chromium migrate from the wastes in the
future. These measures are designed to detect chromium migration
and, if necessary, take corrective action. These measures will
provide protection in the event of chromium migration over the
long-term and thus assure the long-term effectiveness of the
remedy. The rationale for ~he action levels set for the
contingencies for future action are provided in Subsection 2,
concerning groundwa~er, below.
The implem~ntation of the source control alternative also
requires the enactment of legislatively-created institutional
controls, i~e.., the enactment of a state law converting the site
property into a state conservation area. The use of
legislatively-created institutional controls is central to the
protectiveness and effectiveness of the selected remedy. By
9 In discussing the contamination detected at the Site
which originated from the tannery wastes, EPA notes that the
arsenic detected in on-site groundwater is not believed to be
-------
ROD DECISION SUMMARY,.
SACO TANNERY WASTE PITS SITE
Paqe 41
converting the Site into a conservation area under state law, the
selected remedy assures that the soil cover system will not be
disturbed or destroyed, and that it will be adequately
maintained.
It should be noted that EPA does not ordinarily consider the use
.of institutional controls to restrict use or access to a site as
an adequate substitute for active response measures. Alternative
SC-3A, which requires the installation of a soil cover system,
does not use institutional controls as a substitute for active
response measures. Nevertheless, EPA believes that the
significant reliance on institutional controls at this site is
only appropriate because special circumstances are present.
First, EPA has selected an alternative that relies significantly
on institutional controls because the State refused to concur on
the ~ore costly alternative, SC-5. Without the State's
concurrence, and its agreement to assist in paying for the
remedial action, Alternative SC-5, which uses treatment
technologies, could not be implemented.
Second, by requiring the passage of a state law, in addition to
the use of deed restrictions, ~he institutional controls used at
this Site will be the most effective possible. EPA believes that
the enactment of a state law to restrict future uses of the Site,
and to assure future maintenance of the soil cover, provides
greater protection than other institutional controls. A
conservation area operated by public officials under state law
will provide a rigorously enforced, highly reliable institutional
control.
, ,
Third, the STWP site is particularly suited for conversion into a
conservation area. The entire site consists of 233 acres of
land, which is mostly forested. The 233 acres are located
adjacent to a rural, residential area which is not densely
populated at this time. In addition, the site contains 53 acres
of wetlands, and is-therefore suited to land use restrictions
which will prohibit the future development of the site. All of
these geographic qonsiderations indicate that legislatively-
created institutional controls will be effective in providing
. future protection to the soil cover system.10
to..
other source control alternatives considered for the STWP site
are less acceptable than the selected source control remedy for
the following reasons. Alternative SC-l and SC-2, the no-action
10 During the five year reviews of the Site, EPA will
evaluate whether the institutional controls enacted at the site
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ROD DECISION SUMMARY' .
SACO TANNERY WASTE PITS SITE
Paqe 42
alternatives, did not address risks from exposure pathways' and
are therefore not protective of human health and the environment.
Alternative SC-3, the cover system, was not selected because it
did not include legislatively-created institutional controls to
prohibit future uses of the Site. This alternative also did not
include a monitoring system to detect releases of chromium or a
contingency for further evaluation and treatment. Alternative
'SC-4, involving in-situ solidification, was rejected, even though
it used treatment technologies, because of implementability
problems. Alternative SC-S is the alternate remedy that will be
implemented if an adequate state statute is not enacted within
two years from the date that the ROD is signed. Alternatives SC-
6 and SC-7, involving excavation and disposal of wastes in an on-
site disposal area or landfill, were perceived to be too costly
to gain State acceptance and not as effective in the long-term as
the selected remedy. Alternatives with a present worth cost in
excess of $90 million (Alternatives SC-9 and SC-IO) were rejected
due to implementability problems.
The State concurs with the selected source control remedy and
agrees to assist in paying for the remedial action. . The public
comments received during the public comment period also indicate
that the public generally concurs with or does not oppose the
selected source control remedy.
2.
Groundwater
The components of the source control and groundwater portions of
the selected remedy overlap in certain respects. Like the source
control alternative, the groundwater monitoring component of the
selected remedy is designed to detect increasing contaminant
concentrations on-site, contaminant migration off-site, and to
build in a contingency for future actions at the Site if
necessary.
In particular, the selected groundwater remedy includes a
groundwater monitoring program to detect possible future releases
of contaminants from the wastes. Further, the selected remedy
also'includes specific monitoring requirements with respect to
chromium, which has the known potential. to leach from the wastes,
and ,with respect to arsenic, which is present at the Site at
,levels in excess of its MCL. Overall, the groundwater portion of
the selected remedy represents the best remedial groundwater
alternative for the Site, in comparison to the no action
groundwater alternative and the pump and treat groundwater
alternative under consideration.
a.
Rationale for the creation of a monitoring network
to detect contaminant migration from the waste to
the groundwater'
-------
ROD' DECISION SUMMARY! "
SACO TANNERY WASTE PITS SITE
Paqe 43
The investigations of the STWP site demonstrate that contaminants
detected in the soils and ,sludges have not migrated to the
groundwater at the Site. In fact, arsenic is the only
groundwater contaminant present at the site at levels in excess
of its MCL, and arsenic is not believed to be associated with the
tannery wastes disposed of at the Site." To address concerns
that contaminants might begin to migrate from the wastes in the
future, a groundwater monitoring program was selected for the
site.
The groundwater monitoring program will provide an early warning
of contaminant levels changes at the Site. Groundwater standards
for all contaminants except arsenic are currently met at the
Site, and the monitoring program will demonstrate whether these
standards continue to be met in the future. In the event that
contaminants, other than arsenic, are detected in any of the
monitoring wells at levels in excess of their MCLs further
evaluation of the Site will be performed and the need for an
additional groundwater remedy will be assessed.
EPA believes that this monitoring program, with a contingency
plan for future evaluation, is protective of human health and the
environment. The monitoring program will provide an effective
means to detect possible future contaminant migration at the
Site. The contingencies for further evaluation based on
exceedances of the action levels assure that additional steps
will be taken at the site if necessary in the future. These
contingency plans provide sufficient time to perform additional
remedial actions at the Site because site contaminants are not
expected to migrate through the groundwater at a rapid rate.
This portion of the groundwater remedy is not designed to reduce
the'mobility, toxicity, or volume of contaminants. Instead, the
groundwater monitoring network serves to detect any contaminant
migration from the wastes to the groundwater, increasing
contaminant concentrations on-site, or off-site migration of
contamination.
b.
Rationale for the requirements under the
, monitoring program with respect to chromium
With respect to chromium, EPA has determined that chromium has
the potential to leach from the waste to the groundwater.
Although there is no evidence that chromium has leached from the
wastes at the Site, the groundwater monitoring program includes a
" The portion of the groundwater remedy which involves
groundwater monitoring for arsenic is discussed in Section
-------
ROQ DECISION SUMMARY"
SACO TANNERY WASTE PITS SITE
Paqe 44
commitment to treat soils and sludges located at the site in the
future under certain circumstances.
The MCL level for chromium is 50 ppb. Like the contingency for
further actions with respect to other contaminants detected at
the Site, if chromium is detected in any of the monitoring wells
at levels in excess of 50 ppb (the MCL), further evaluation of
"the site will be performed. This groundwater response will aim
to assure that exceedances of MCLs for chromium are addressed and
that groundwater standards continued to be attained. Based on
such further evaluation, it may be possible to remedy chromium
exceedances through such measures as a groundwater pump and treat
system.
However, if chromium is detected in any monitoring wells situated
at and around the site boundary at levels above 500 ppb, wastes
at the Site will be treated following evaluation of treatment-
based remedial alternatives. EPA considers the 500 ppb action
level, ten times the current MCL level for chromium, to be
sufficiently significant to trigger implementation of a source
control alternative that uses treatment. The type of treatment
alternative that would be performed if this contingency developed
is not specified at this time because treatment choices should be
based on the best available technology the time that wastes at
the site undergo treatment.
EPA believes the monitoring program will provide an effective
means to detect chromium migration from the wastes to the
groundwater. The contingency for treatment of chromium also
provides assurance that, at certain levels, wastes at the site
will undergo treatment. Because chromium migration is not
expected to occur at a rapid rate, there would be sufficient time
to treat the wastes at the site if necessary. EPA believes that
it "will be feasible to excavate wastes at the Site even after
installation of the soil cover system for two reasons. First,
the wastes at the site are visibly distinguishable from the clean
soils located next to the waste pits and lagoons. Second, the
use of a geotextile-fabric prior to installation of the soil
cover and waste pit and lagoon markers will assist in identifying
the buried wastes. "
c.
Rationale for the selection of groundwater
monitoring with respect to arsenic.
4
The selected groundwater alternative is also designed to address
arsenic contamination detected on-site through groundwater
monitoring. Given current site conditions, the conversion of the
Site into a conservation area with the prohibition of groundwater
use, and the establishment of Alternate Concentration Limits at
the site, groundwater monitoring of arsenic levels satisfies
-------
ROD. DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 45
EPA's remedial selection criteria.
In comparing the available groundwater alternatives, EPA
considered the following site characteristics.
Arsenic was the only contaminant detected in monitoring well
samples at concentrations greater than its MCL. Arsenic was
detected in 11 of 32 monitoring wells at concentrations greater
than the Contract Required Detection Limit (CRDL) of 10 ppb.
Only four shallow monitoring wells in till contained arsenic at
concentrations greater than the MCL of 50 ppb. However, other
monitoring wells in equally close proximity to the pits or
lagoons have not shown arsenic levels exceeding MCLs. None of
the 34 residential wells sampled from the surrounding area
outside the site boundaries contained arsenic at levels above the
CRDL.
.
Arsenic has been detected in stream sediments (16 ppm at station
SED-103) in off-site stream sediments at a location upstream of
the pits and lagoons. This indicates there are sources of
arsenic in the area other than the waste disposal activities on-
site. These sources may include naturally occurring arsenic, or
the use of agricultural pesticides containing arsenic. Portions
of the site and abutting areas to the west have been or are
currently being farmed. On-site soils considered to be
unaffected by the disposal of tanning wastes indicated background
concentrations of arsenic at approximately 14 ppm. Arsenic
concentrations in the pits and lagoons are quite variable and are
not significantly above background, and arsenic is generally not
associated with tannery wastes.
Based on these data, EPA believes that arsenic concentrations in
groundwater above MCLs are localized in certain portions of the
Site and.have no definable source area (s). Thes.e localized
plumes may represent arsenic mobilized by changes in the
geochemical environment due to the interaction of tannery waste
materials and nativ~ groundwater or aquifer materials. Transport
distances of arsenic above MCLs are expected to be. short with
mechanisms of attenuation reducing concentrations below MCLs at
or before the plumes reach the on-site streams.
As discussed in Section 5.4.2.3 of the Phase II RI Report, data
indicate that site groundwater, including the four monitoring
well locations with arsenic MCL exceedances, discharges on-site
into three surface water bodies: Stuart Brook, an unnamed
tributary to Stuart Brook, and an unnamed tributary to Cascade
Brook. No arsenic was detected in surface water samples from
these streams. Three stream sediment samples contained arsenic
greater than the site soil background level of 14 ppm in
-------
ROD DECISION SUMMARY
SACO TANNERY WASTEtPITS SITE
Paqe 4~
ARARs exist for this sediment contamination. These lev~ls are
within the carcinogenic risk range of 10-4 (290 ppm) and 10-5 (29
ppm). These levels are most probably the result of arsenic
adsorbed on soil particles migrating with overland flow from the
seep area located near the northern berm of Chromium Lagoon 2,
"rather than from subsurface migration through the groundwater.
Further migration from the seep will be prevented by the source
" control remedy.
The hydrogeologic investigations indicate that the effects of
residential well pumping in the Site vicinity are not felt in on-
site monitoring wells. Groundwater off-site currently meets all
MCLs. Therefore, arsenic concentrations on-site do not impact
off-site drinking water receptors.
Site conditions as a whole suggest that active restoration of the
groundwater is not practicable, given the absence of a defined
sour~e area, the diffuse nature of the contamination, and the
localization of the contamination in random areas of the Site.
For these reasons, it would be difficult to design a pump and
"treat system that would effectively treat the arsenic
contamination detected at the site.
In addition to the site characteristics, EPA has considered the
unusual nature of the institutional controls at the Site in
selecting the groundwater remedy. Under the state law converting
the Site into a conservation area, the use of the groundwater at
the Site for drinking water purposes will be prohibited. EPA
believes that the legislatively-created institutional controls to
be used at the Site will be effective in permanently prohibiting
future groundwater use and that groundwater monitoring,
therefore, will provide a protective groundwater alternative.
Finally, the groundwater remedy will meet ARARs because EPA is
invoking the provisions of CERCLA ~121(d) (2) (B) (ii), which allow
the Agency to supplant MCLs for arsenic with Alternate
Concentration Limits (ACLs) because certain statutory criteria
are satisfied. CERCLA ~121{d) (2) (B) (ii) provides for ACLs in
lieu of MCLs where three conditions in the statute are met, as
follows:
Q
(l) There are known or projected points of entry of such
groundwater into surface water;
(2) On the basis of measurements or projections, there is or will
be no statistically significant increase of such constituents
from such groundwater into such surface water at the point of
entry or at any point where there is reason to believe
-------
ROD.DECISION SUMMARY -
SACO TANNERY WASTE PITS SITE
Paqe 47-
(3) The remedial action includes enforceable measures -that will
preclude human exposure to the contaminated groundwater at any
point between the facility boundary and all known and projected
points of entry of such groundwater into surface water then the
assumed point of exposure may be at such known and projected
points of entry.
EPA believes that the conditions for setting ACLs are met at this
site. First, points of entry of groundwater into surface water
are located at discharge zone(s) which contain the on-site
streams. of Stuart Brook, an unnamed tributary to Stuart Brook, or
an unnamed tributary to Cascade Brook. (See Figure 8) Although
there has been no known regular human use of these streams, these
streams serve as a potential point of exposure for humans or
animals to arsenic if transported via groundwater.
The second requirement of CERCLA ~121(d) (2) (B) (ii) is satisfied
because, to date, no arsenic has been detected in the stream
surface water. As stated above, transport distances of arsenic
above MCLs are expected to be short with mechanisms of
attenuation reducing concentrations below MCLs at or before the
plumes reach the on-site streams.
Finally, the remedial action includes enforceable institutional
controls that will preclude human exposure to contaminated
groundwater. The conversion of the site property into a
conservation area under state law, and the use of deed
restrictions, will preclude the use of on-site groundwater for
drinking water. In addition, at the STWP site, the point of
exposure will be set at the on-site streams and along the
property boundary for the Site. The point of exposure is a
location where environmental or human receptors are expected to
be exposed to groundwater or surface water. Exposure to
groundwater/surface water at the point of exposure cannot result
in an endangerment to human health or the environment. At the
STWP site, 'no arsenic has been detected in surface water from on-
site streams. Monitoring of the surface water will be conducted
in the future. Further, along the site boundary, arsenic has not
been detected in groundwater at levels in excess of the MCL.
Groundwater monitoring along the site boundary will be conducted
to assure that exceedances of the MCL for arsenic are not
detected at the site boundary in the future.
Based on the above findings, EPA is setting as ACLs for arsenic
the currently observed maximum arsenic levels detected in four
on-site monitoring wells. The point of compliance of ACLs will
be the well locations where ACLs will be monitored. Future
monitoring will be performed to assure that ACL levels continue
to be met in these four wells and to assure that the requirements
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Page 47"
.Lo."'- ... -~.
"'L..------If'L_-,..-
"
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ROD DECISION SUMMARY,
SACO TANNERY WASTE PITS SITE
Paqe 48
will serve to trigger evaluations of whether future remedial
actions will be necessary. Other triggers for this decision are
described in section X.B,'Continqencies for Future Actions, of
this ROD.
In sum, groundwater monitoring for arsenic will satisfy the
"requirements of CERCLA, because it will be protective of human
health and the environment, comply with ARARs, and provide an
effective means to detect changes in the levels of arsenic
contamination on-site. Alternative Concentration Limits (ACLs)
have been established at the Site for arsenic, and for no other
site contaminants. Although the selected groundwater remedy does
not use treatment technologies, EPA has determined the pumping
and treating the groundwater would present design and
implementation problems.
d.
Comparison to other groundwater alternatives.
In comparison to the other groundwater remedies considered for
the Site, the selected groundwater monitoring alternative
represents the best remedial alternative for groundwater at the
Site. The no action alternative (GW-l) is not protective of
human health and the environment because it would not reduce the
risk posed by ingestion of contaminated on-site groundwater. The
pump and treat alternative (GW-3) does not provide a practicable
solution because the source of the arsenic contamination is not
known and an effective pump and treatment system would be
difficult to design.
The State has concurred with this portion of the groundwater
portion of the selected remedy. Several members of the public
expressed support for the installation of a water line to provide
protection from possible future contaminant migration. The
provision of a water line is not appropriate, however, because
groundwater from the site is not at this time impacting the water
quality of off-site' residential wells.
XI.
STATUTORY DETERMINATIONS
The remedial action selected for implementation at the Saco
Tannery Waste pits Site is consistent with CERCLA and, to the
extent practicable, the NCP. The selected remedy is protective
of human health and the environment, attains ARARs, and is cost
effective. The selected remedy does not, however, satisfy the
statutory preference for treatment which reduces the mobility,
toxicity, or volume of waste as a principal element.
Nevertheless, given the State's refusal to concur on the first
-------
ROD DECISION S'QMMARY '. .
SACO TANNERY WASTE PITS SITE
Paqe 49
to the maximum extent practicable.
statutory determinations regarding the alternate remedy are
provided in Section XIV.
A.
The Selected Remedy is Protective of Human Health and
the Environment
From the risk assessment, EPA concluded that if the Site were
used for residential purposes, there would be an increased risk
to human health posed by contact with and ingestion of
contaminated soils and sludges. EPA also concluded that if
groundwater were to be used as a source of drinking water, it
would pose a threat to human health. Environmental receptors
that use the waste pits and lagoons for habitat and food are also
at risk due to site contaminants. The selected remedy
specifically addresses all of these risks. In addition, the
selected remedy addresses the risk that chromium might begin to
leach from the wastes to the groundwater at some future time.
Because the soils and sludges at the Site will be covered by
several feet of till and loam materials, the remedy will
eliminate the risk posed by contact with or ingestion of
contaminants found in the waste pits and lagoons. Bio-intrusion
barriers, consisting of a layer of rock and gravel, will be used
where necessary to prevent burrowing animals from coming into
contact with the contaminated soils. By installing the cover
system, environmental receptors will be inhibited from using the
waste pits and lagoons for habitat and food. The use of a soil
cover system, consisting of several feet of different layers of
soil and other materials will provide effective, long-term
protection to the public and environmental receptors from contact
with or ingestion of contaminated soils.
Monitoring of the groundwater for chromium, with a contingency
for further evaluation and treatment of the soils if necessary,
reduces the threat 6f harm posed by the pdssible migration of
chromium in the future. By implementing a groundwater monitoring
>system to detect releases of chromium," any future migration- of
chromium from the waste into the groundwater should be detected.
Moreover, the establishment of a contingency for treatment of the
wastes in the event that significant levels of chromium migrate
from the waste in the future provides further protection to human
health and the environment.
The risk of future exposure to contaminated soils due to
destruction of the cover system will be eliminated through the
use of legislatively-created institutional controls by which the
site property will be converted into a state conservation area.
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ROD DECISION' SUMMARY"
SACO TANNERY WASTE PITS SITE
Paqe 50
system will also be properly maintained and protected.
With respect to the groundwater located at the Site, under the
state law converting the site property into a conservation area,
the future use of on-site groundwater for drinking water purposes
will be prohibited. Risks from ingestion of on-site groundwater
will be reduced or eliminated through the use of the
legislatively-created institutional controls, the groundwater
monitoring program, and the contingency for further evaluation of
the site in the event that current levels of on-site arsenic and
other contaminants increase in the future, or begin to move off-
site.
In sum, EPA finds that the selected remedy will be fully
protective of human health and the environment because it
effectively addresses all of the risks posed by the site.
. B.
The Selected Remedy Attains ARARs
This remedy will attain all applicable or relevant and
appropriate federal and state requirements that apply to the
site. Federal environmental laws that are applicable or relevant
and appropriate to the selected remedial action at the Saco
Tannery Waste Pits site include the:
Resource Conservation and Recovery Act (RCRA)
Clean Water Act (CWA)
Clean Air Act (CAA)
occupational Safety and Health Administration
u.S. Fish and wildlife Coordination Act
(OSHA)
State environmental laws that are applicable or relevant and
appropriate to the selected remedial action at the site include:
Maine
Maine
Maine
Maine
Maine
Maine
Hazardous Waste Management Rules
Solid Waste Management Rule: Landfill Disposal
Ambient Air Quality Standards
Freshwater Wetlands Act
Standards for Classification of Minor Drainages
Standards for Classification of Groundwater
Facilities
Table 9 and Table 10 list the chemical specific and location
specific ARARs, respectively, and discuss how they were
considered in the development and evaluation of remedial
alternatives. Table 11 lists the action specific ARARs, presents
a brief synopsis of the requirements, and outlines the action
which will be taken to attain the ARARs.
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Page
SOa (1
TABLE 9 --
CHEMICAL~SPECIFIC ARARS
REQUIREMENT
REQUIREMENT SYNOPSIS/CONSIDERATION
Safe Drinking Water
Act Regulations
establishing Maximum
Contaminant Levels
(MCLs), 40 C.F.R.
Part 141, Subpart B
Maine Drinking Water
Rules, C.M.R. 10-
l44A, Chapter 231,
Section 7
Maine RUles-Relating
to Testing of
Private Water
Systems for
Potentially
Hazardous .
Contaminants, C.M.R.
10-144A, Chapter 233
Maine Standards for
Classification of
Fresh Surface
Waters, 38 M.R.S.A.
These regulations establish contaminant
concentration levels in public drinking
water. With respect to the selected
remedy, these regulations will be
relevant and appropriate for all
contaminants, with the exception of
arsenic for which ACLs have been
established. The MCL for arsenic will,
however, be relevant and appropriate at
the point of exposure in on-site streams
and in monitoring wells at and around
the site boundary. with respect to the
alternative remedy, the groundwater
remedy is an interim remedy only, and
these regulations will be relevant and
appropriate for all contaminants.
These regulations establish contaminant
concentration levels in public drinking
water. With respect to the selected
remedy, these regulations will not be
remedy, these regulations will not be
ARARs on-site because a state statute
will prohibit the use of groundwater at
the Site for drinking water purposes.
With respect to the alternate remedy,
the groundwater remedy is an interim
remedy only, and these regulations will
be relevant and appropriate.
These regulations establish maximum
exposure guidelines for numerous
inorganic and organic compounds in
water. With respect to the selected
remedy, these regulations will not be
ARARs on-site because a state statute
will prohibit the use of groundwater at
the Site for drinking water purposes.
with respect to the alternate remedy,
the groundwater remedy is an interim
remedy only, and these regulations will
be relevant and appropriate.
Stuart Brook is a Class B water, as
Class B is defined under this applicable
-------
~ 465
Maine standards for
Classification of
Groundwater, 38
M.R.S.A. ~~ 465c &
470
To Be Considered
Federal Ambient
Water Quality
crit~ria (AWQC)
o
. ~ . '.
Page.50a (2
The groundwater at the site is
classified as GW-A, as GW-A is defined
under this applicable law.
AWQC are health and environment based
criteria developed for carcinogens and
non-carcinogens. AWQC will be
considered in monitoring on-site
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. ,~. ' .
Page SOb (
TABLE 10 - LOCATION SPECIFIC ARARS
REQUIREMENT
REQUIREMENT SYNOPSIS/CONSIDERATION
Discharge of Dredged
and Fill Materials
Regulations, 40
C.F.R. ~ 230,
promulgated under
Section'404 of the
Clean Water Act
U.S. Fish and
WildJ,ife
Coordination Act, 16
U.S.C. ~ 661
Wetlands Executive
Order, (E.O. 11990),
and EPA regulation
40 C.F.R. Part 6
Executive Order
11988 and EPA
regulation 40 C.F.R.
Part 6
Maine Freshwater
Wetlands Act, 38
M.R.S.A., Chapter 3,
~g 405-410
Maine Hazardous
Waste Management
R~:~s, 38 M.R.S.A. ~
l.:~t 5 eq. ,
c ~:-s 800-802,
Under this applicable requirement, no
activity that adversely affects a
wetland shall be permitted if a
practicable alternative with lesser
effects is available. At the Saco
Tannery Waste Pits site, there is no
practicable alternative having lesser
effects other that filling or excavating
the waste pits and lagoons.
EPA had complied with this applicable
law by consulting with the U.S. Fish and
Wildlife Service concerning the effect
of the remedial action on the wetland
area.
The Wetlands Executive Order and this
EPA regulation are applicable and were
weighed in the evaluation of remedial
alternatives. During the remedial
action, steps will be taken to minimize
the adverse affects upon the wetlands
and destroyed wetlands will be re-
created.
The floodplains Management Executive
Order and this EPA regulation are
applicable and were weighed in the
evaluation of remedial alternatives.
During the performance of the selected
or alternate remedy, steps will be taken
to minimize any adverse impacts on the
floodplains. The impact on the
floodplain is expected to be minimal
because the waste pits and lagoons do
not lie within the floodplain.
These relevant and appropriate standards
regulating activities in the vicinity of
a wetland will be met.
These relevant and appropriate
regulations outline general requirements
for the construction of hazardous waste
facilities in Maine, including
-------
, ,
850, 851, 853-857
Maine Standards for
Classification of
,Minor Drainages, 38
M.R.S.A., Chapter 3,
~ 468
Maine Alteration of
Rivers, Streams, and
Brooks, 38 M.R.S.A.
~ 425 et sea.
Maine Water
Pollution Control
Law: . Solid Waste
Disposal Area:
Location, 38
M.R.S.A., Chapter 3,
Article 2, ~ 421
Maine Standards for
Classification of
Groundwater, 38
M.R.S.A., Chapter 3,
~ 470
Maine site Location
Act, 38 M.R.S.A.
Chapter 3, ~~ 481-
490 .
Maine Solid Waste
Management Rules:
Landfill Disposal
Facilities, 38
M.R.S.A., ~ 1301 et
~, Chapters 400-
406
v
Page SOb (
a hazardous waste facility in a wetland
or near a floodplain. The remedial
action will comply with appropriate
portions of these regulations.
These applicable regulations which
prohibit the degradation of a Class B
water will be met with respect to stuart
Brook.
EPA will comply with these applicable
regulations which prohibit interference
with the flow or quality of stuart
Brook.
These regulations state that no boundary
of a solid waste disposal area shall lie
closer than 300 feet to any classified
body of surface water. The alternate
remedy will comply with these applicable
regulations. Because the selected
remedy does not involve the construction
of a solid waste disposal area, these
regulations are not applicable or
relevant and appropriate to the selected
remedy.
These applicable regulations which
prohibit the degradation of onsite
groundwater will be met.
These applicable regulations which
prohibit adverse impacts on certain
natural resources will be met.
These relevant and appropriate
regulations concerning the placements of
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. .~ . . .
TABLE 11
Page SOc (
ACTION-SP~CIFIC ARARS FOR SELECTED REMEa~
REQUIREMENT
REQUIREMENT SYNOPSIS/CONSIDERATION
RCRA General
Facility Standards,
40 C.F.R. 99 264.10-
264.18
RCRA Preparedness
and Prevention, 40
C.F.R. 99 264.30-
264.37
RCRA' Contingency
Plan and Emergency
Procedures, 40
C.F.R. 99 264.50-
254.56
RCRA Closure
Regulations,
Landfills, 40
9 264.310
C.F.R.
RCRA Groundwater
Protection
standards, 40 C.F.R.
Part 264, Subpart F
RCRA Closure and
Post-Closure, 40
C.F.R. 99 264.110-
264.120, and 264.310
and Part 264,
Subpart F
These relevant and appropriate
regulations concern general waste
analysis, site security, and training.
Substantive portions of these
regulations will be met.
These relevant and appropriate
regulations outline the requirements for
safety equipment and spill control.
Substantive portions of these
regulations will be met.
These relevant and appropriate
regulations require the development and
implementation of a contingency plan in
the event of fire, explosion, or release
of hazardous waste constituents.
Substantive portions of these
regulations will be met.
The cover system will be designed and
constructed to meet these relevant and
appropriate regulations. Requirements
related to permeability and minimization
of migration are relevant but not
appropriate at this Site because all of
the waste pits and lagoons are located
in a high water -table area, which would
limit the effectiveness of an
impermeable cover.
The groundwater monitoring program will
comply with these relevant and
appropriate regulations.
These regulations are relevant and
appropriate after installation of the
soil cover. These regulations include
provisions for development of a post-
closure plan, maintenance, and
-------
National Ambient Air
Quality standards
(NAAQS) for PM10, 40
C.F.R. ~ 50.6-50.7,
promulgated pursuant
to the Clean Air Act
National Ambient Air
.Quality standards
(NAAQS) for lead, 40
C.F.R. ~ 50.12,
promulgated pursuant
to the 'Clean Air Act
Executive Order
11988 and EPA
regulation 40 C.F.R.
Part 6
Executive Order
11990 and EPA
Regulation 40 C.F.R.
Part 6
OSHA General
Industry Standards,
29 C.F.R. Part 1910
OSHA Safety and
Health Standards for
Federal Service .
Contracts, 29 C.F.R.
Part 1926
OSHA Recordkeeping,
Reporting, and
Related Regulations,
29 C.F.R. Part 1904
~
Page SOc (
These regulations outline the maximum
primary and secondary' 24-hour - .
concentrations for particulate matter.
This regulation is applicable during
construction of the remedial action.
This regulation establishes ambient
quality standards for lead. This
regulation is applicable during
construction of the remedial action.
air
The Floodplains Management Executive
Order and this EPA regulation are
applicable and were weighed in the
evaluation of remedial alternatives.
During the installation of the soil
cover system steps will be taken to
minimize any adverse impacts on the
floodplains. The impact on the
floodplain is expected to be minimal.
The Wetlands Executive Order and this
EPA regulation are applicable and were
weighed in the evaluation of remedial
alternatives. During the remedial
action, steps will be taken to minimize
the adverse affects upon the wetlands
and destroyed wetlands will be re-
created.
These applicable regulations contain
safety and health standards that will be
met during all remedial activities.
These applicable regulations contain
safety standards that will be met during
all remedial activities.
Substantive portions of these applicable
regulations, concerning employer
recordkeeping and reporting regulations,
will be met during all remedial
-------
, ~. '.
Pretreatment
Regulations for
Indirect Discharges
to POTWs, 40 C.F.R.
Part 403
Discharge of Dredged
and Fill Materials
Regulations, 40
C.F.R. ~ 230,
promulgated under
section '404 of the
Clean Water Act
u.s. Fish and
WildJ,ife
Coordination Act, 16
U.S.C. ~ 661
Maine Hazardous Waste
Management Rules,
38 M.R.S.A. ~ 1301
et sea., Chapters
800-802, 850, 851 &
853-857
Maine Solid Waste
Management Rules:
Landfill Disposal
Facilities, 38
M.R.S.A. ~ 1301 et
~, Chapter 401
Maine Ambient Air
Quality. Standards,
38 '" M . R . S . A. ,
~.5-S4,
Chapter 110
Maine Freshwater
Wetlands Act,
38 M.R.S.A.,
Chapter 3,
~~ 405-410
Page SOc (
These regulations control the discharge
of pollutants into POTWs. If standing
water from the waste pits is discharged
to a POTW, these regulations will be
applicable and the remedy will comply
through pretreatment.
This regulation applies to the use of
fill material in wetlands. The selected
remedy will comply with this regulation
because there is no practicable
alternative to filling the waste pits
and lagoons, because steps will be taken
to minimize adverse impacts during
remediation, and because new wetlands
will be recreated onsite.
EPA has complied with this applicable
law by consulting with the u.s. Fish and
Wildlife Service concerning the effect
of the remedial action on the wetland
area.
These relevant and appropriate
regulations outline general requirements
for the construction of hazardous
waste facilities in Maine.
The soil cover system will be installed
in compliance with appropriate
portions of these regulations.
The soil cover system will be
comply with these relevant and
appropriate standards for
landfill disposal facilities.
The applicable ambient air
quality standards will
not be exceeded during the
performance of the on-site
construction work.
These relevant and appropriate
standards regulating activities
in the vicinity of a wetland
-------
Maine Standards. for
Classification of Minor
Dra"inages, 38
M.R.S.A., Chapter 3,
S 468
Maine Standards for
Classification of
Groundwater, 38
M.R.S.A., Chapter 3,
SS 465-C and 470
Maine Alteration of
Rivers, Streams, and
Brooks, 38 K.R.S.A.,
Chapter 3, S 425 et
~.
(.)
(
Page SOc (
These applicable regulations
which prohibit the degradation
of a Class B water - -
will be met with respect to
S.tuart Brook.
These applicable regulations
which will prohibit the degradation
of on-site groundwater
will be met.
These applicable regulations which will
prohibit interference with the flow or
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Ron DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 51-
1.
Action-specific ARARs
The source control portion of the selected remedy will involve
covering the waste pits and lagoons with a soil cover system,
prohibiting the future development of the Site under state law,
and monitoring the groundwater to detect releases of chromium
from the contaminated soils and sludges. The groundwater portion
'of the remedy will involve restricting the future use of on-site
groundwater for drinking water purposes and monitoring the levels
of groundwater contamination found on the Site.
a.
Federal
The Resource Conservation and Recovery Act (RCRA) governs the
transportation, storage, treatment and disposal of hazardous
wastes. In general, RCRA will not be an applicable requirement
at the Saco Tannery Waste Pits site, but will be relevant and
appropriate.
Under 40 C.F.R. 9261.4 (b) (6), wastes that fail the EP Toxicity
test due to the presence of chromium, or because they are listed
due to the presence of chromium, and which are not hazardous for
any other reason (i.e., they do not fail the EP characteristic
for any constituent but chromium, do not fail for any other
characteristic, or are not listed for any other reason), are not
considered hazardous wastes under RCRA, provided that:
(A) The chromium in the waste is exclusively (or nearly
exclusively) trivalent chromium; and
(B) The waste is generated from an industrial process which uses
trivalent chromium exclusively (or nearly exclusively) and the
process does not generate hexavalent chromium; and
(C) The waste is typically and frequently managed in non-
oxidizing environments.
EPA has determined that the provisions of 40 C.F.R. ~ 261.4
.(b)(6) (known as the tannery waste exclusion) are satisfied and
',that no listed or characteristic wast€s are found at the Site.12
For this reason, RCRA will not be applicable. Specific
provisions of RCRA will be relevant and appropriate because they
address and provide technical guidance for the same kinds of
12 EP Toxicity tests were performed during the
investigation of the site on arsenic, barium, chromium, lead,
mercury, and selenium found at the Site. Chromium was the only
one of these contaminants found at the site that failed the EP
-------
ROD. DECISION SUMMARY.
SACO TANNERY. WASTE PITS SITE
Paqe 52-
actions as those that will be taken at the STWP site. - -
u
EPA will comply with the substantive provisions of RCRA
regulations governing: Standards for Owners and Operators of
Hazardous Waste Treatment, storage and Disposal Facilities,
General Facility Standards (40 C.F.R. ~~ 264.10-264.18);
Preparedness and Prevention (40 C.F.R. ~9 264.30-264.37;
'contingency Plan and Emergency Procedures (40 C.F.R. ~~ 264.50-
264.56); Releases From Solid Waste Management Units (groundwater
protection) (40 C.F.R. ~~ 264.90-264.101); and Closure and Post-
Closure - Landfills (40 C.F.R ~~ 264.110-264.120 & 264.310, and
Part 264, subpart F).
In accordance with RCRA closure regulations, the selected remedy
will.meet the requirements that the final cover (1) functions
with minimum maintenance; (2) promotes drainage and minimizes
erosion or abrasion of the final cover; and (3) accommodates
settling and subsistence so that the integr~ty of the cover is
maintained. Requirements related to the long-term minimization
of migration of liquids and permeability will not be appropriate
because waste materials within the disposal pits and lagoons lie
below the high water table and impermeable covers therefore will
not provide a successful means of preventing liquids from
percolating through the wastes.
The Hazardous and Solid Waste Amendments to RCRA (HSWA) land
disposal restrictions (LDR) are not applicable or relevant and
appropriate to the selected remedy because the selected remedy
does not involve placement of the wastes.
with respect to standing water to be pumped from the waste pits
and that may be directed to a POTW, EPA will comply with
applicable regulations under the Clean Water Act concerning
Pretreatment Standards for POTW Discharge (40 C.F.R. Part 403).
Regulations under the occupational Safety and Health Act (OSHA)
apply to the performance of the remedial action as it involves
workers at the site~ EPA will comply with OSHA regulations
. including the General Industry Standards (29 C.F.R. Part 1910);
safety and Health Standards (29 C.F.R. Part 1926); and the
substantive provisions of the Record Keeping, Reporting and
Related Regulations (29 C.F.R. Part 1904).
During the performance of the remedy, EPA will also comply with
the Clean Air Act and the National Ambient Air Quality Standards
(NAAQS) for PM\O (40 C.F.R. ~~ 50.6-50.7) and lead (40 C.F.R. ~
50.12). Fugit~ve dust emissions caused by site activities will
not exceed these ambient air quality standards.
-------
ROD'DECISION. SUMMAR~
SACO TANNERY WASTE PITS SITE
Paqe 53
provided in the subsection 3 below, concerning locatio~ specific
ARARs.
b.
State
The selected remedy will also attain action-specific Maine ARARs,
including the Maine Hazardous Waste Management Rules (38 M.R.S.A.
~ 1301 et sea., Chapters 800-802, 850, 851, & 853-857) (only
appropriate portions of these regulations will be met); Maine
Solid Waste Management Rules: Landfill Disposal Facilities (38
M.R.S.A'. ~ 1301 et sea., Chapter 401); Maine Ambient Air Quality
Standards (38 M.R.S.A. ~ 584, Chapter 110); Maine Freshwater
Wetlands Act (38 M.R.S.A. Chapter 3, ~~ 405-410); Maine Standards
for Classification of Minor Drainages (38 M.R.S.A. Chapter 3, ~
468); and Maine Standards for Classification of Groundwater (38
M.R.S.A. Chapter 3, ~ 465-C and 470).
'2.
Chemical-Specific ARARs
In determining which contaminants at the site required
remediation, EPA considered both Federal ARARs and potential
State ARARs.
ARARs for groundwater contaminants at the STWP site, with the
exception of arsenic, are the Maximum contaminant Levels (MCLs)
promulgated under the Safe Drinking Water Act (40 C.F.R. ~
141.11-141.16). Maximum Contaminant Levels are applicable only
at the tap and not to an aquifer directly. Because, however, the
groundwater at the STWP site is classified as Class lIB under the
EPA groundwater protection strategy and must be considered a
possible source of drinking water, the Federal MCLs are relevant
and appropriate in setting cleanup levels. As indicated earlier,
Alternative Concentrations Levels (ACLs) have also been
. established for arsenic in four on-site monitoring wells, in
accordance with CERCLA ~121(d) (2) (B) (ii). The selected
groundwater remedy will meet the standards set by MCLs and, with
respect to arsenic, ACLs.
.
Although the state of Maine's MCLs '(10-144A C.M.R. Chapter 231)
and Maximum Exposure Guidelines (MEGs) (10-144A C.M.R. Chapter
233) are potential ARARs for the groundwater, the State of Maine
has determined that these standards are not applicable or
relevant and appropriate to the performance of the selected
alternative. Maine classifies all groundwater in the state as a
minimum Class GW-A, suitable for drinking water. However, at the
STWP site, state law will prohibit the use of on-site groundwater
for drinking water purposes. For this reason, the State of Maine
has determined that State MCLs and MEGs are not appropriate
remediation standards.
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ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
. " .
Paqe 54..
Federal Ambient Water Quality Criteria (AWQC) are health and
environmental based criteria developed for carcinogens and non-
carcinogens. AWQC will be considered in monitoring on-site
streams.
3.
Location-Specific ARARS
I ~
.During the remedial action, EPA will install a soil cover system
over the waste pits and lagoons. The two waste lagoons and a
number of the waste pits have formed manmade wetlands. Because
there is no practicable alternative, these manmade wetlands will
be destroyed during remediation. The remedial action will comply
with section 404 of the Clean Water Act and with standards set by
Maine requirements, including Maine Freshwater Wetlands Act (38
M.R.S.A. chapter 3, section 405-410) and the Maine Hazardous
Waste Management Rules (38 M.R.S..A. ~ 1301 et sea., Chapters
800-802, 850, 851, 853-857), governing actions that take place in
a we~land. The remedial action will also comply with the
Wetlands Executive Order (E.O. 11990) and the Fish and Wildlife
Coordination Act (16 U.S.C. ~ 661). Following installation of
the soil cover system, EPA will create compensatory wetlands to
the extent required by federal and state wetlands ARARs to
reestablish wetlands that will be lost during remediation.
The remedial action will also comply with the Floodplain
Management Executive Order (E.O. 11988) and EPA regulation 40
C.F.R. Part 6, which implements the Executive Order. Although
approximately 30 acres of the site lie within a lOO-year
floodplain, none of the waste pits, lagoons, and contaminated
sediment areas lie within the floodplain. Thus, the soil cover
system will not be installed within the floodplain.
Nevertheless, during the performance of the remedial action,
steps will be taken to minimize any adverse impacts on the
floodplains.
The remedial action will also comply with Maine standards for
Classification of Minor Drainages (38 M.R.S.A. Chapter 3, ~ 468)
and Maine Alteration of Rivers, Streams, and Brooks (38 M.R.S.A.
Chapter 3, .~ 425 et sea.), which will prohibit the degradation of
stuart Brook, and Maine Standards for Classification of
Groundwater (38 M.R.S.A. Chapter 3, ~ 470), which will prohibit
the degradation of on-site groundwater. Finally, the remedial
action will comply with the Maine site Location Law (38 M.R.S.A.
Chapter 3, section 481-490), which prohibits adverse impacts on
certain natural resources.
..-
C.
The Selected Remedial Action is Cost Effective
'-'
Of those remedial alternatives that are protective and attain
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ROD DECISION SUMMARY! .
SACO TANNERY WASTE PITS SITE
Paqe 55
The estimated total present worth cost of the source control and
groundwater components of ~he selected remedy is $10 million.
The estimated capital costs are $6.6 to $6.8 million, depending
on the number of wells used, and the estimated cost of operations
and maintenance is $2.5 to $3.8 million, depending on the number
of wells used.
In comparison to the other alternatives considered for the Site,
the cost of the selected remedy is less than the cost of the
treatment-based alternatives considered and less than the cost of
those remedies that involved resource recovery. Leaving aside
SC-5, the alternate remedy, the treatment-based alternatives, SC-
4, SC-6, and SC-7, have a range of estimated present worth costs
between $15 million and $29 million. Each of these alternatives
was rejected in part due to technical, implementation, or long-
term effectiveness considerations. Alternatives SC-9 and SC-10,
whicn involve resource recovery, have estimated present worth
costs of $107 million and $93 million respectively. These costly
alternatives also used uncertain technologies and required a
considerable amount of further testing prior to implementation.
In comparison to the alternate remedy, which includes Alternative
SC-5 and Alternative GW-2, the selected remedy is substantially
less expensive. The estimated present worth cost of Alternative
SC-5 is $33.8 million and the estimated present worth cost of
Alternative GW-2 is $321,000. In spite of the differences in
cost between the selected remedy and the alternate remedy, they
each provide a similar degree of protection to human health and
the environment assuming that contaminants do not migrate from
the wastes in the future.
Finally, the groundwater monitoring program to be implemented
under the selected remedy will be less costly than the pump and
treat groundwater alternative (GW-3). In addition, EPA has
determined that the pump and treat alternative presents several
potential design an9 implementation problems.
Table.12 provides a summary of present worth costs for the source
control and groundwater alternatives respectively.
D.
The Selected Remedy utilizes Permanent Solutions and
Alternative Treatment or Resource Recovery Technologies
to the Maximum Extent Practicable
Given the State's refusal to concur with the first Proposed Plan,
the selected remedy utilizes permanent solutions to the maximum
extent possible.
-------
I'rt r, e-' ~: I
c
c
TABLE 12
REMEDIAL ALTERNATIVES C0~. COMPARISON
SACO TANNERY WASTE PITS SITE
SACO. MAINE
CAPITAL POST-CLOSURE FIVE-YEAR-
REMEDIAL ALTERNATIVE COSTS ANNUAL OPERATING COSTS ANNUAL COST REVIEW COSTS TOTAL COST
($) (PRESENT WORTH $) (PRESENT WORTH $) (PRESE NT (PRESENT WORTH $)
WORTH $)
~-1: No action 0 0 0 57,000 57,000
:-2: Imtitutional Action 252.500 246,000 0 57,000 555,500
5,841,000 ' 9,500 122,000 57,000
=- 3: Cover System 6,029,500
:-3A: Cover System with 6,661,600 9,500 2,488,500 - 3,692,300 57,000 9,211,600-10,551,400
Institutional Controls
:-4: In.Situ Solidification 14,893,000 9,500 122,000 57,000 15,081,500
-,.".
. 5 l ;:(avation c:,otidification, 32,892,000 426,000 407,000 57,000 33,782,000
Un-Site RCI), Landfill . -
-.
:-b: f.xcavation, Solidification, 26,946,000 146,000 549,000 57,000 27,698,000
On- Site Disposal Area
-...-.-
:-7: Excavation, On-Site RCRA 24,146,000 4,434,000 412,000 57,000 29,049,000
Landfill
:-9: Soil Washing 107,452,000 39,000 0 57,000 107,548,000
~-10: Excavation, On-Site 92,822,000 26,000 0 57,000 92,905,000
IlicinNation
. ........
";1-,. I'JoAction 0 0 0 57,000 57,000
-....~ .
N-!.: Institutional Action 38,200' GW-2A1Site-Wide Monitoring: 0 I
I
1,345,000 57,000 GW-2A: 1,440,200
GW-2B/Chemical Specific GW-2B: 321,200
Monitoring: 226,000
--
,lid Treat by 1,571,000 2 Years Pumping: 409,000 0 2 Years Pumping: 2,037,000
I.-tipitation, 5 Years Pumping: 952,000 57,000 5 Years Pumping: 2,580,00.0
Flocculation, 10 Years Pumping: 1,699,000 10 Yea~s Pumping: 3,327,000:
(Iarification
:
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ROD DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 56- ,
EPA proposed in the first Proposed Plan, SC-5. Alternative SC-5
involves the excavation; solidification, and disposal 'of
solidified wastes in an on-site RCRA landfill. Alternative SC-5
thus provides for a perma~ent disposition of the wastes at the
Site without site-wide land use restrictions or an extensive
groundwater monitoring network. Without DEP's concurrence, and
its agreement to assist in paying for the costs of the cleanup,
,Alternative SC-5 could not be implemented. EPA therefore
reconsidered and revised its preferred alternative and issued a
revised Proposed Plan. Because alternative SC-5 could not be
implemented without DEP's concurrence, EPA believes that the
selected remedy utilizes, to the maximum extent possible, a
permanent solution.
EPA's selected remedy does not utilize an alternative treatment
technology.
E.
The Selected Remedy Does not Satisfy the
Preference for Treatment as a Principal Element
The selected remedy does not include treatment and thus does not
satisfy the preference for treatment. Treatment-based
alternatives were rejected because of DEP's refusal to concur
with the proposed alternative SC-5, because other treatment based
alternatives were perceived to be too costly to gain state
acceptance, or because components of certain treatment-based
alternatives were technically impractical. The rejection of
these treatment-based alternatives is discussed in Section X.C.l.
XII.
STATE ROLE
The Maine Department of Environmental Protection has reviewed the
various alternatives and has indicated its support for the
selected remedy and for the alternate remedy (Alternative SC-5).
The State has also reviewed the Phase II Remedial Investigation,
Risk Assessment, Feasibility Study, FS Addendum, and Wetlands and
Floodplains Assessm~nt Report to determine if the selected remedy
is in compliance with applicable or relevant and appropriate
State environmental laws and regulations ." On the basis of these
analyses, the State of Maine concurs with the selected remedy and
the alternate remedy for the Saco Tannery Waste Pits site, and
agrees to implement and enforce the institutional controls and
land use restrictions components of the selected remedy and the
alternate remedy. The State of Maine also certifies that the
selected remedy and the alternate remedy for the Saco Tannery
Waste Pits site comply with all applicable or relevant and
appropriate State environmental laws and regulations. A copy of
-------
ROD DECISION SUMMARY -
SACO TANNERY WASTE!PITS SITE
Paqe 57
*
*
*
XIII.
THE ALTERNATE REMEDY
As indicated earlier, this Record of Decision includes an
alternate remedy. This alternate remedy will become effective in
the event that the state does not enact an adequate state law
converting the Site into a state conservation area, or adequate
regulations or agreements implementing the state law, within two
years from the date on which this ROD is signed on September 27,
1989. If an adequate law, and adequate regulations or
agreements, are not enacted, and in effect, within two years of
September 27, 1989, i.e., on September 27, 1991, the alternate
remedy will be effective and will be implemented.
This-alternate remedy includes both a source control (SC-5) and a
groundwater component (GW-2). A detailed conceptual discussion
of the source control and groundwater component can be found in
Sections 7.2.5 and 8.3.2 respectively of the Feasibility Study.
A.
Description of the Alternate Remedy
1.
Remedial Action Objectives
The remedial
identical to
remedy. For
Section X.A.
action objectives for the alternate remedy are
the remedial action objectives for the selected
a discussion these remedial action objectives, see
2.
Target Cleanup Levels, Areas Requiring
Remediation, and Action Levels
The target cleanup levels, and areas requiring remediation, for
sludge and sediment for the alternate remedy are identical to the
target cleanup levels, and areas requiring remediation, for
sludge and sediment-for the selected remedy. The alternate
~,remedy would involve excavating all waste pits and lagoons to the
,jnterface between the visibly contaminated sludge layer and the
clean soil. Further sampling, prior to excavation of the wastes,
would only be required in the wet area near Waste pit 9 and the
seep area adjacent to Chromium Lagoon 2, in order to determine
the area of wastes requiring remediation.
Action levels for groundwater remediation have not been
established because the groundwater monitoring provided under the
alternate remedy is intended to be an interim remedy only.
Further action will be taken with respect to groundwater
-------
ROD. DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 58-
selected and performed at a future time.
B.
Description of Remedial Components
site Preparation: site preparation will include clearing and
grubbing to prepare the site for remedial activities. See Figure
7-8 in the Feasibility Study for a conceptual site layout for
"remediation. Before remedial construction begins on-site, a
fence will be installed around the construction area to deter
vandalism and minimize public exposures to construction
activities during remedial activities. Warning signs will be
posted along the fence and at the entrance gate. The current
lock at the entrance gate will be inspected to insure its
integrity and will be replaced if it is in deteriorating
condition. Roadways will be designed and constructed to minimize
environmental impact while providing adequate access for
construction equipment.
.
Remove Ponded Water from Pits and Laqoons and Treat at Off-site
Facilitv: Ponded water will be pumped from each waste pit and
lagoon and transported off site for treatment at a commercial
water treatment facility, or, alternatively, at a local POTW.
This process will occur on a pit by pit basis as the pits are
excavated.
Excavate contaminated Material: contaminated material from
designated areas (pits, lagoons, solid waste area, wet area, and
Chromium Lagoon 2 seep area) will be excavated and transported to
treatment units with equipment such as backhoes, bulldozers,
front-end loaders, and dump-trucks. To minimize odor problems,
excavated materials will not be stockpiled at the Site and will
undergo treatment immediately following excavation. Solid waste
and sludge disposed in the Chromium Lagoon 2 fill area will be
separated by a screening mechanism. After separation, sludge and
soils will be treated and solid waste material will be shredded.
and disposed of in the on-site landfill.
-J
Solidify contaminated Material: As the contaminated material is
excavate~, it will be mechanically mixed with solidification/
stabilization reagents in a plant mixing unit. " Processing
equipment will be either a mobile processing plant or a semi-
stationary plant. Based on the results of the solidification/
stabilization treatability studies conducted at the STWP site,
preliminary mix proportions of about 30-percent fly ash, 10-
percent high calcium quick lime are recommended. The exact
proportions and recommended sequence of field mixing procedures
will be established by means of an extensive sludge sampling and
laboratory/field testing program during remedial design. Test
protocol during site remediation may include regular analysis of
fly ash for inorganic constituents. Additional strength
-------
ROD"DECISIO~ SUMMARy.
SACO TANNERY WASTE PITS SITE
Paqe 59"
development and leachate tests will also be conducted-on the 25-
percent cement kiln dust mix to determine whether this mix should
be further considered for use in final remediation of the site.
The goal is to use a mixture that meets compressive strength
requirements while minimizing the possibility of contaminant
migration. The TCLP test and various strength tests are likely
candidates as performance specifications. Treatability test
.information is summarized in section 7.2.4.1 of the Feasibility
Study.
Place Solidified Material in an On-site RCRA Landfill:
Solidified material and shredded solid waste will be placed in a
landfill constructed on site. A conceptual discussion of the
landfill design, construction, and operations is contained on
pages 7-86 through 7-100 of the Feasibility Study. Detailed
design criteria for the landfill will be developed during
remedial design to allow for the use of the most current
materials and procedures appropriate for the specific conditions
at the Site. The proposed conceptual landfill design, as
presented in the FS, will comply with RCRA Landfill Requirements
(40 C.F.R. Part 264, Subpart N) for hazardous waste landfills and
will include a gravity fed leachate collection system.
Backfill and Re-Establish Veqetation in pits. Chromium Laqoon 2
and Wet Area: Existing pits and Chromium Lagoon 2 may be
restored as wetlands. Alternatively, empty pits and lagoons will
be filled with common-borrow soil material. soil material would
be filled to a level that would promote runoff. The wet area
behind Waste pit 9 would be filled to existing grade. The
backfilling task would occur after waste has been excavated from
each specific area; backfilling and revegetating would be
performed while landfill and treatment operations are taking
place.
Create Compensatory Wetlands Area On-site: Following the
landfilling of the solidified wastes, wetlands of equal or higher
value will be recreated to the extent required by federal and
state wetlands ARARs. Given the levels of contaminated wastes
disposed of at the Site, there is no practicable alternative to
excavating the waste pits and lagoons that would have a lesser
impact on the wetlands. Restoration of wetlands in the area of
the existing pits and lagoons may be a more favorable approach
than creating a new area for wetland restoration. In siting and
developing compensatory wetlands, EPA will consider potential
effects on groundwater flow or adverse impacts on other aspects
of the remedial actions. In order to re-create wetlands of equal
or higher value, the functional attributes of the wetlands
presently on site will be further evaluated during remedial
design. The Baseline Wetlands Assessment and the Ecological Risk
Assessment provide some of the. necessary information to evaluate
-------
ROD DECISION SUMMAR~ .
SACO TANNERY WASTE PITS SITE
Paqe 60
o
the functional attributes of the STWP wetlands. Further
evaluation is required concerning the following functional
attributes of the wetland~: hydrologic functions, water quality
functions, habitat functions, ecosystem functions, and
socioeconomic functions. A yearly operation and maintenance
program to be developed during remedial design will be required
.for several years after construction of wetland areas.
Additionally, a monitoring program to be developed during
remedial design will be required to evaluate the wetland sediment
and water quality and the success of the wetland in meeting the
hydroldgical, biological, and cultural functions necessary for
the STWP site. section 7.2.3 of the Feasibility Study includes a
discussion on establishing compensatory wetlands.
Post-Closure Monitorinq and Maintenance of Landfill: Post-
closure monitoring and maintenance will be conducted in
acco~dance with RCRA post-closure regulations (40 C.F.R. Part
264, . Subpart G). The facility will be operated in accordance
with substantive portion of the RCRA General Facility Standards
(40 C.F.R. Part 264, Subpart B). Post-closure activities will
include: leachate collection, maintenance of the landfill cap,
and overall inspections.
A monitoring program will be developed to evaluate the
effectiveness of the landfill. The groundwater monitoring system
will be developed and maintained to comply with the requirements
of 40 C.F.R. Part 264, Subpart F.
Land Use and Groundwater Use Restrictions: Institutional
controls such as deed restrictions and/or local ordinances will
be implemented or enacted to restrict activities which may
destroy the protectiveness of the cap and to prohibit the use of
on-site groundwater as drinking water.
The duration and scope of institutional controls prohibiting the
use of on-site groundwater as drinking water will be reassessed
periodically based on sampling results and observed trends. At a
minimum this reassessment will occur during each five-year site
review described below.
Interim Groundwater Remedv - Perform Environmental Monitorinq on
Groundwater/Surface Water: A water quality monitoring program
will be implemented to track contaminant distribution, migration
and attenuation over time.
~
To monitor the levels and movement of arsenic and other selected
target compounds, monitoring wells will be sampled quarterly for
selected target compounds (including bu~ not limited to arsenic,
lead, manganese, chlorobenzene.and bis(2-ethyl-hexyl]phthalate).
-------
Page 61a
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-------
ROD DECISION SUMMARY
SACO TANNERY WASTE : PITS SITE
Paqe 6-1
selected locations in on-site streams twice a year, during low
and high flow seasons, and analyzed for selected target compounds
(including but not limited to arsenic, chromium, lead, manganese,
chlorobenzene and bis[2-ethyl-hexyl]phthalate) .
"A residential well sampling program will be instituted with the
objective of collecting periodic samples for selected target
compounds from existing and new residential wells in use along
Hearn and Flag Pond Roads within the area shown on Figure 9.
Additipnally, if new residential wells are installed along Hearn
and Flag Pond Roads, water-level data will be collected to
monitor for possible changes in on-site groundwater flow patterns
(as it affects contaminant distribution). The water level
monitoring program will be accomplished through the periodic use
of continuous recorders on selected monitoring wells during
seasonal low water periods.
The sampling and monitoring programs presented above will be
conducted for at least three years beyond the completion of
construction phase of the remedial action. At that time, the
frequency and list of analytes monitored in the groundwater and
surface water will be reassessed. If the water level monitoring
program is instituted, and residential well use is subsequently
reduced below current usage, the water level monitoring program
would be reevaluated and possibly discontinued. Similarly, the
residential well sampling program will be reevaluated and
modified based on reductions of residential well use.
Conduct Five-Year site Review: Because this alternative would
result in contaminants remaining on-site, EPA will review the
site at least once every five years after the initiation of the
remedial action at the site to assure that the remedial action
continues to be protective of human health and the environment.
This review will be consistent with the CERCLA standards"
applicable for five-year site reviews in effect at the time of
the review. If justified by the five-year review, remedial
actions, such as installation of a groundwater extraction and
treatment system or installation of an alternate water supply may
be evaluated, required, recommended and/or "implemented. EPA will
also evaluate the risks posed by the site at the completion of
the remedial action (i.e., before the site is proposed for
deletion from the NPL).
ESTIMATED TIME FOR CONSTRUCTION: 3 to 4 years
ESTIMATED CAPITAL COST: SC-5 - $32,892,000, GW-2 - $38,200
ESTIMATED 0 & M COST (Present Worth): SC-5 - $890,000
GW-2 - $283,000
SC-5 - $33,782,000
GW-2 - $321,200
c
-------
o
u
~
ROD. DECISION SUMMARY
SACO TANNERY WASTE PITS SITE
Paqe 62-
Table 7-18 and Table 8-13 in the FS provide cost breakdowns for
SC-5 and GW-2 respectively.
C.
Rationale for Selection of an Alternate Remedy
The rationale for choosing the alternate remedy is based on the
assessment of each criteria listed in the evaluation of
alternatives section of this document, and also described in
section X.C, concerning the selected remedy. Based on an
assessment of the evaluation criteria, and the statutory
preferences of CERCLA, EPA selected an alternate remedy for the
site in addition to the selected remedy.
The alternate remedy involves excavating and solidifying the
sludge from the waste pits and lagoons, consolidating and
disposing of the solidified material in a RCRA hazardous waste
landfill to be constructed on site, and monitoring the
groundwater at the site. Except for minor changes in its
description, this alternative is identical to the preferred
alternative that was recommended for the site by EPA in the first
Proposed Plan, issued in July 1988. After the State refused to
concur with this remedial alternative, EPA adopted the selected
remedy for the remediation of the site.
Under the selected remedy, the State of Maine is required to
enact a state law permanently converting the site property into a
state conservation area, and to adopt regulations or enter into
agreements with EPA implementing the state law. If an adequate
state law, and adequate regulations or agreements, are not
enacted or adopted, and in effect, within two years from the date
that the ROD is signed, the alternate remedy will become
effective. Thus, if the selected remedy cannot be implemented,
the alternate remedy will become effective.
The alternate remedy is protective of human health and the
environment, will attain federal and state applicable or relevant
and appropriate public health and environmental requirements, and
uses treatment technologies and..permanent solutions to the
maximum extent practicable.
Through the use of excavation, solidification, and placement in a
RCRA landfill, the source control component of the alternate
remedy will permanently and significantly reduce the mobility of
hazardous contaminants at the site. EPA believes that excavation
of the wastes at the site can be performed safely and
effectively. There is little potential for discharge of
contaminants from the wastes to the groundwater during
excavation, and during performance of the alternate remedy in
-------
ROD. DECISIO~ SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 63-
has been used at Superfund sites and other hazardous waste sites
across the country with sludges similar to those found at the
STWP site. Treatability studies performed on sludge from the
Site during the FS demonstrate that solidification is a feasible
alternative and that it can successfully reduce the potential of
chromium to leach from the wastes. Additional protection is
provided by this alternative due to the placement of solidified
wastes in a RCRA landfill. The use of a RCRA landfill will
minimize freeze-thaw and precipitation effects, as well as
collect leachate. The combination of excavation, solidification
and landfilling provided under this remedy will provide
effective, technically feasible, long-term protection to human
health and the environment.
Finally, with respect to groundwater, the groundwater component
of the alternate remedy will be an interim remedy only, and
groundwater conditions will be re-evaluated during the first five
year 'review of the Site.13
Although the State initially rejected this remedy when it was
presented in the first Proposed Plan for the Site, the state has
concurred with the use of this remedy as an alternate to the
selected remedy. No public comments were received during the
second public comment period concerning the alternate remedy.
X~.
STATUTORY DETERMINATIONS FOR ALTERNATE REMEDY
A.
The Alternate Remedy is Protective of Human Health and
the Environment
The site risks, as described earlier, include: an increased risk
to human health posed by contact with and ingestion of
contaminated soils and sludges, an increased risk to human health
posed by ingestion of on-site drinking water, an increased risk
to environmental receptors posed by exposure to site
contaminants, and a risk to human health and the environment
posed by the potential for chromium to leach from the waste to
the groundwater at some future time. The alternate remedy
addresses all of these risks.
13 Because the land use restrictions prohibiting use of the
groundwater at the site for drinking water under the alternate
remedy do not depend on the passage of a state statute, and are
not as effective as the land use restrictions provided under the
selected remedy, EPA will perform an interim remedy for
groundwater at this time and re-evaluate the groundwater portion
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ROD. DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 64-
Under the alternate remedy, the soils and sludges will be
excavated, solidified, and contained in a RCRA landfill to be
constructed on-site. By this action, the contaminants contained
in the two waste lagoons and 53 disposal pits will be
qonsolidated in one area of the Site and contained within a
secure landfill. Thus, the alternate remedy will effectively
eliminate the risk posed by contact with or ingestion of
'contaminants found in the waste pits and lagoons.
The consolidation, treatment, and containment of the wastes in an
on-sit~ landfill will also significantly reduce the threat of
harm posed by the possible migration of contaminants from the
wastes in the future. The use of treatment technologies to
solidify the waste will reduce the threat that hazardous
substances will be able to migrate from the solidified waste.
Even in the event that contaminants should begin to migrate from
the solidified waste, the use of a double liner barrier in the
RCRA'landfill will prevent the release of contaminants from the
landfill itself.
Groundwater monitoring will effectively monitor changes in
groundwater conditions. In addition, the use of institutional
controls at the site will prohibit the use of on-site groundwater
for drinking water purposes. Given that groundwater
contamination is limited on-site, and that the future use of the
on-site groundwater will be prohibited, the alternate remedy will
provide adequate protection to human health and the environment.
As an interim remedy, the groundwater component of the alternate
remedy will be reassessed during the first five-year review of
the site. .
Finally, with respect to the performance of the alternate remedy,
it. should be noted that continuous ambient air monitoring will be
conducted near waste pits and site boundaries during remediation
to evaluate the effect of the remedial action on air quality in
the vicinity of the site and the residential area near the site.
In addition, workers on site will use the necessary health and
safety protection fOr dermal contact and inhalation.
B.
The
Alternate Remedy Attains ARARs
'.
This remedy will attain all applicable or relevant and
appropriate federal requirements that apply to the site. Federal
environmental laws from that are applicable or relevant and
appropriate to the alternative remedial action at the Saco
Tannery Waste pits site include the:
'"
Resource conservation and Recovery Act (RCRA)
Clean Water Act (CWA)
-------
ROD-DECISION SUMMAR~
SACO TANNERY WASTE PITS SITE
Paqe 65
Occupational Safety and Health Administration (OSHA)
u.S. Fish and Wildlife Coordination Act
State environmental laws that are applicable or relevant and
appropriate to the alternative remedial action at the Site
include:
Maine
Maine
Maine
Maine
Maine
Maine
Maine
Hazardous Waste Management Rules
Solid Waste Management Rule: Landfill
Ambient Air Quality Standards
Freshwater Wetlands Act
Standards for Classification of
Standards for Classification of
Hexavalent Chromium Particulate
Disposal Facilities
Minor Drainages
Groundwater
Emissions standard
Table 13 and Table 14 list the chemical specific and location
specific ARARs, respectively, and discuss how they were
considered in the development and evaluation of remedial
alternatives. Table 15 lists the action specific ARARs, presents
a brief synopsis of the requirements, and outline the action
which will be taken to attain the ARARs.
A brief narrative summary of the ARARs for the alternate remedy
follows.
1.
Action-specific ARARs
The source control portion of the alternate remedy will involve
excavating the wastes from all of the waste pits and lagoons,
solidifying these wastes, and placing the solidified material in
a RCRA landfill which will be constructed on-site. The
groundwater portion of the alternate remedy will involve
prohibiting the future use of on-site groundwater for drinking
and monitorinathe levels of arsenic and other contaminants found
in on-site.gr~undwater. The institutional controls used to
restrict the future use of on-site groundwater will consist of
deed restrictions a~d/or local ordinances.
a.
Federal
The Resource Conservation and Recovery Act (RCRA) governs the
transportation, storage, treatment and disposal of hazardous
wastes. In general, RCRA will not be an applicable requirement
at the Saco Tannery Waste pits site, but will be relevant and
appropriate.
Under 40 C.F.R. ~ 261.4 (b) (6), wastes that fail the EP Toxicity
test due to the presence of chromium, or because they are listed
due to the presence of chromium, and which are not hazardous for
-------
Page 65a (
TABLE 13 --
CijEMICAL'--SPECIFIC ARARS
.. ',.
REQUIREMENT
REQUIREMENT SYNOPSIS/CONSIDERATION
u
(j
Safe Drinking Water
Act Regulations
establishing Maximum
'contaminant Levels
(MCLs), 40 C.F.R.
Part 141, Subpart B
Maine Drinking Water
Rules, C.M.R. 10-
l44A, Chapter 231,
Section 7
Maine Rules Relating
to Testing of
Private Water
Systems for
Potentially
Hazardous:
contaminants, C.M.R.
10-144A, Chapter 233
~
<;
Maine Standards for
Classification of
Fresh Surface
Waters, 38 M.R.S.A.
These regulations establish contaminant
concentration levels in public drinking
water. With respect to the selected
remedy, these regulations will be
relevant and appropriate for all
contaminants, with the exception of
arsenic for which ACLs have been
established. The MCL for arsenic will,
however, be relevant and appropriate at
the point of exposure in on-site streams
and in monitoring wells at and around
the site boundary. With respect to the
alternative remedy, the groundwater
remedy is an interim remedy only, and
these regulations will be relevant and
appropriate for all contaminants.
These regulations establish contaminant
concentration levels in public drinking
water. With respect to the selected
remedy, these regulations will not be
remedy, these regulations will not be
ARARs on-site because a state statute
will prohibit the use of groundwater at
the site for drinking water purposes.
With respect to the alternate remedy,
the groundwater remedy is an interim
remedy only, and these regulations will
be relevant and appropriate.
These regulations establish maximum
exposure guidelines for numerous
inorganic and organic compounds in
water. WIth respect to the selected
remedy, these regulations will not be
ARARs on-site because a state statute
will prohibit the use of groundwater at
the site for drinking water purposes.
With respect to the alternate remedy,
the groundwater remedy is an interim
remedy only, and these regulations will
be relevant and appropriate.
stuart Brook is a Class B water, as
Class B is defined under this applicable
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~ 4"65
Maine standards for
Classification of
Groundwater, 38
M.R.S.A. ~~ 465c &
470
To Be Considered
Federal Ambient
Water Quality
Criteria (AWQC)
Page 65a (
The groundwater at the site t~
classified as GW-A, as GW-A is defined
under this applicable law.
AWQC are health and environment based
criteria developed for carcinogens and
non-carcinogens. AWQC will be
considered in monitoring on-site
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Page 65b (
. . ~. '.
TABLE 14 - LOCATION SPECIFIC ARARS
REQUIREMENT
REQUIREMENT SYNOPSIS/CONSIDERATION
,~
o
Discharge of Dredged
~nd Fill Materials
Regulations, 40
C.F.R. ~ 230,
promulgated under
Section' 404 of the
Clean Water Act
U.S. Fish and
Wildlife
Coordination
U.S.C. ~ 661
Act, 16
Wetlands Executive
Order, (E.O. 11990),
and EPA regulation
40 C.F.R. Part 6
Executive Order
11988 and EPA
regulation 40 C.F.R.
Part 6
',)
Maine Freshwater
Wetlands Act, 38
M.R.S.A., Chapter 3,
~~ 405-410
-G
Maine Hazardous
Waste Management
Rules, 38 M.R.S.A. ~
1301 et seq.,
Chapters 800-802,
Under this applicable requirement, no
activity that adversely affects a
wetland shall be permitted if a
practicable alternative with lesser
effects is available. At the Saco
Tannery Waste Pits site, there is no
practicable alternative having lesser
effects other that filling or excavating
the waste pits and lagoons.
EPA had complied with this applicable
law by consulting with the U.S. Fish and
Wildlife Service concerning the effect
of the remedial action on the wetland
area.
The Wetlands Executive Order and this
EPA regulation are applicable and were
weighed in the evaluation of remedial
alternatives. During the remedial
action, steps will be taken to minimize
the adverse affects upon the wetlands
and destroyed wetlands will be re-
created.
The floodplains Management Executive
Order and this EPA regulation are
applicable and were weighed in the
evaluation of remedial alternatives.
During the performance of the selected
or alternate remedy, steps will be taken
to minimize any adverse impacts on the
floodplains. The impact on the
'. floodplain is expected to be minimal.
because the waste pits and lagoons.do
not lie within the floodplain.
These relevant and appropriate standards
regulating activities in the vicinity of
a wetland will be met.
These relevant and appropriate
regulations outline general requirements
fer the constr;~~ion of hazardous waste
fa~~lities i~ :ne, including
-------
. .~. ' .
850, 851, 853-857
Maine Standards for
Classification of
Minor Drainages, 38
. M.R.S.A., Chapter 3,
~ 468
Maine Alteration of
Rivers~ Streams, and
Brooks, 38 M.R.S.A.
~ 425 et sea.
Maine Water
Pollution Control
Law: . Solid Waste
Disposal Area;
Location, 38
M.R.S.A., Chapter 3,
Article 2, ~ 421
Maine Standards for
Classification of
Groundwater, 38
M.R.S.A., Chapter 3,
~ 470
Maine Site Location
Act, 38 M.R.S.A.
Chapter 3, ~~ 481-
490
..
Maine Solid Waste
Management Rules:
Landfill Disposal
Facilities, 38
M.R.S.A., ~ 1301 et
~, Chapters 400-
406
Page 65b I
a hazardous waste facility in a wetland
or near a floodplain. The remedial
action will comply with appropriate
portions of these regulations.
These applicable regulations which
prohibit the degradation of a Class B
water will be met with respect to Stuart
Brook.
EPA will comply with these applicable
regulations which prohibit interference
with the flow or quality of Stuart
Brook.
These regulations state that no boundary
of a solid waste disposal area shall lie
closer than 300 feet to any classified
body of surface water. The alternate
remedy will comply with these applicable
regulations. Because the selected
remedy does not involve the construction
of a solid waste disposal area, these
regulations are not applicable or
relevant and appropriate to the selected
remedy.
These applicable regulations which
prohibit the degradation of onsite
groundwater will be met.
These applicable regulations which
prohibit adverse impacts on certain
natural resources will be met.
These relevant and appropriate
regulations concerning the placements of
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, ,f, '.
Page 65c (
ACTION-SPECIFIC ARARS FOR ALTERNATE REMEDY
TABLE 15 --
REQUIREMENT SYNOPSIS/CONSIDERATION
~
REQUIREMENT
u
RCRA General
Facility Standards,
'40 C.F.R. ~~ 264.10-
264.18
RCRA Preparedness
and Prevention, 40
C.F.R. ~~ 264.30-
264.37
RCRA.Contingency
Plan 'and Emergency
Procedures, 40
C.F.R. ~~ 264.50-
254.56
RCRA Groundwater
Protection
Standards, 40 C.F.R.
Part 264, Subpart F
RCRA Closure and
Post-Closure -
Landfills, 40 C.F.R.
Part 264, Subparts
F, G, & N
National Ambient Air
Quality Standards
(NAAQS) for PM10, 40
C.F.R. ~ 50.6-50.7,
promulgated pursuant
to the Clean Air Act
v
National Ambient Air
Quality Standards
(NAAQS) for lead, 40
C.F.R. ~ 50.12,
promulgated pursuant
to the Clean Air Act
-
Executive Order
11990 and EPA
These relevant and appropriate
regulations concern general waste
analysis, site security, and training.
Substantive portions of these
regulations will be met.
These relevant and appropriate
regulations outline the requirements for
safety equipment and spill control.
Substantive portions of these
regulations will be met.
These relevant and appropriate
regulations require the development and
implementation of a contingency plan in
the event of fire, explosion, or release
of hazardous waste constituents.
Substantive portions of these
regulations will be met.
The groundwater monitoring program will
comply with these relevant and
appropriate regulations.
These regulations are relevant and
appropriate to the construction and
maintenance of the RCRA landfill. These
regulations include provisions for
development of a post-closure plan,
maintenance, and groundwater monitoring.
--
These regulations outline the maximum
primary and secondary 24-hour ,
concentrations for particulate matter.
This regulation is applicable during
construction of the remedial action.
This regulation establishes ambient air
quality standards for lead. This
regulation is applicable during
construction of the remedial action.
The Wetlands Executive Order and this
-------
regulation 40 C.,F.R. 'd '
Part 6
Executive Order
11988 and EPA
regulation 40 C.F.R.
Part 6
OSHA General
Industry Standards,
29 C.F.R. Part 1910
OSHA Safety and
Health Standards for
Federal Service
Contracts, 29 C.F.R.
Part 1926
OSHA Recordkeeping,
Reporting, and
Related Regulations,
29 C.F.R. Part 1904
Pretreatment
Regulations for
Indirect Discharges
to POTWs, 40 C.F.R.
Part 403
Discharge of Dredged
and Fill Materials
Regulations, 40
C.F.R. ~ 230,
promulgated under
section 404 of the
Clean Water Act
u.S. Fish and
wildlife
Coordination Act, 16
U.S.C. ~ 661
Page 65c (
weighed in the evaluation of remedial
alternatives. During the remedial,
action, steps will be taken to minimize
the adverse affects upon the wetlands
and destroyed wetlands will be re-
created.
The Floodplains Management Executive
Order and this EPA regulation are
applicable. During the performance of
the remedial action, steps will be taken
to minimize any adverse impacts on the
floodplains. The impact on the
floodplain is expected to be minimal
because the waste pits and lagoons are
not located in the floodplain.
These applicable regulations contain
safety and health standards that will be
met during all remedial activities.
These applicable regulations contain
safety standards that will be met during
all remedial activities.
Substantive portions of these applicable
regulations, concerning employer
recordkeeping and reporting regulations,
will be met during all remedial
activities.
These regulations control the discharge
of pollutants into POTWs. If standing
water from the waste pits is discharged
to a POTW, these regulations will be
applicable and the remedy will comply
through pretreatment.
This regulation applies to the use of
fill material in wetlands. ,The selected
remedy will comply with this regulation
because there is no practicable
alternative to filling the waste pits
and lagoons, because steps will be taken
to minimize adverse impacts during
remediation, and because new wetlands
will be recreated onsite.
EPA has complied with this applicable
law by consulting with the u.S. Fish and
wildlife Service conce:r-ning the e:fect
-------
Maine Hazardous
Waste Management
Rules, 38 M.R.S.A. ~
1301 et seq.,
Chapters 800-802,
850, 851 & 853-857
Maine Solid Waste
Management Rules:
Landfill Disposal
Facilities, 38
M.R.S.A. ~ 1301 et
~, Chapter 401
Maine Ambient Air
Quality Standards,
38 M.R.S.A., ~ 584,
Chapter 110
Maine Freshwater
Wetlands Act, 38
M.R.S.A., Chapter 3,
~ ~ 405-410
Maine Standards for
Classification of
Minor Drainages, 38
M.R.S.A., Chapter 3,
S 468
Maine Standards for
Classification of
Groundwater, 38
M.R~S.A., Chapter 3,
~ 465-C and 470
Maine Hexavalent
Chromium Particulate
Emissions Standards,
38 M.R.S.A. SS 585,
585-A, Chapter 135
Page 65c (
. .
area.
These relevant and appropriate
regulations outline general requirements
for the construction of hazardous waste
f'acilities in Maine. The performance of
the alternate remedy will comply with
appropriate portions of these
regulations.
The alternate remedy will comply with
these relevant and appropriate standards
for landfill disposal facilities.
The applicable ambient air quality
standards will not be exceeded during
the performance of the on-site
construction work.
These relevant and appropriate standards
regulating activities in the vicinity of
a wetland will be met.
These applicable regulations which
prohibit the degradation of a Class B
water will be met with respect to Stuart
Brook. .
These applicable regulations which will
prohibit the degradation of on-site
groundwater will be met.
During the remedial action, chromium
emissions will not exceed the levels
established in these relevant and
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ROD DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 66
for any constituent but chromium, do not fail for any-other
characteristic, or are not listed for any other reason), are not
considered hazardous wastes under RCRA, provided that:
(A) The chromium in the waste is exclusively (or nearly
exclusively) trivalent chromium; and
(B) The waste is generated from an industrial process which uses
trivalent chromium exclusively (or nearly exclusively) and the
process does not generate hexavalent chromium; and
(C) The waste is typically and frequently managed in non-
oxidizing environments.
EPA has determined that the provisions of 40 C.F.R. ~ 261.4
(b) (6) (known as the tannery waste exclusion) are satisfied and
that no listed or characteristic wastes are found at the Site.'4
For this reason, RCRA will not be applicable. Specific
provisions of RCRA will be relevant and appropriate because they
address and provide technical guidance for the same kinds of
actions as those that will be taken at the STWP site.
EPA will comply with the substantive provisions of RCRA
regulations governing: Standards for Owners and Operators of
Hazardous Waste Treatment, Storage and Disposal Facilities,
General Facility Standards (40 C.F.R. ~~ 264.10-264.18);
Preparedness and Prevention {40 C.F.R. ~~ 264.30-264.37;
Contingency Plan and Emergency Procedures (40 C.F.R. ~~ 264.50-
264.56); Releases From Solid Waste Management Units (groundwater
protection) (40 C.F.R. ~~ 264.90-264.101); and Closure and Post-
Closure - Landfills (40 C.F.R Subparts F, G and N).
By contrast, EPA has determined the LDR regulations will not be
relevant and appropriate because the justification for exempting
tannery wastes from. the definition of hazardous wastes under RCRA
also justifies a determination that the LDR regulations are not
relevant and appropriate at the STWP site. See 45 Federal
Register 72035 - 72039 (October, 1980) (indicating that the
. trivalent chromium found in tannery wastes is less mobile and
less toxic than hexavalent chromium).
With respect to standing water from that will be pumped from the
waste pits and that may be directed to a POTW, EPA will comply
with applicable regulated under the Clean Water Act concerning
14 EP Toxicity tests were performed during the investigation
of the site on arsenic, barium, chromium, lead, mercury, and
selenium found at the site. Chromium was the only one of these
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ROD'DECISION SUMMAR~
. '.
SACO TANNERY WASTE PITS SITE
Paqe 67
Pretreatment Standards for POTW Discharge (40 C.F.R. Part 403) .
Regulations under the Occ~pational Safety and Health Act (OSHA)
apply to the performance of the remedial action as it involves
workers at the site. EPA will comply with OSHA regulations
including the General Industry Standards (29 C.F.R. Part 1910):
Safety and Health Standards (29 C.F.R. Part 1926): and the
substantive provisions of the Record Keeping, Reporting and
Related Regulations (29 C.F.R. Part 1904).
During the performance of the remedy, EPA will also comply with
the Clean Air Act and the National Ambient Air Quality Standards
(NAAQS) for PM 10 (40 C.F.R. ~~ 50.6-50.7) and lead (40 C.F.R. ~
50.12). Fugitive dust emissions cause by site activities will
not exceed ambient air quality standards.
A discussion of the ARARs concerning wetlands and floodplains is
provided in subsection 3, below, concerning location specific
ARARs.
b.
State
The selected remedy will also attain action-specific Maine ARARs,
including the Maine Hazardous Waste Management Rules (38 M.R.S.A.
~ 1301 et seq., Chapters 800-802, 850, 851, & 853-857) (only
appropriate portions of these regulations will be met): Maine
Solid Waste Management Rules: Landfill Disposal Facilities (38
M.R.S.A. ~ 1301 et seq., Chapter 401): Maine Ambient Air Quality
Standards (38 M.R.S.A. ~ 584, Chapter 110); Maine Freshwater
Wetlands Act (38 M.R.S.A. Chapter 3, ~ 404-410); Maine Standards
for Classification of Minor Drainages (38 M.R.S.A. Chapter 3, ~
468); Maine Standards for Classification of Groundwater (38
M.R.S.A. Chapter 3, ~ 470); and Maine Hexavalent Chromium
Particulate Emissions Standard (38 M.R.S.A. ~ 585, 585-A, Chapter
135) .
2.
chemical-Specific ARARs
In determine which contaminants at the site required remediation"
EPA considered both Federal and State ARARs.
ARARs for the groundwater contaminants at the STWP site include
the Maximum contaminant Levels (MCLs) promulgated under the Safe
Drinking Water Act (40 C.F.R. ~ 141.11-141.16) and the State of
Maine's MCLs (10-144A C.M.R. Chapter 231) and Maximum Exposure
Guidelines (MEGs) (10-144A C.M.R. Chapter 233). Both the MCLs
and MEGs are legally applicable only at the tap and not to an
aquifer directly. Because, however, the groundwater aquifer at
the STWP site is classified as Class IIB under the EPA
-------
ROD- DECISION SUHMAR¥ ,
SACO TANNERY WASTE PITS SITE
Paqe 68
'-,
it must be considered a possible source of drinking water.
this reason, MCLs and MEGs are relevant and appropriate in
setting cleanup levels.
For
Because the groundwater remedy selected at the Site is an interim
remedy, rather than a final remedy, it is not necessary to attain
.groundwater ARARs at this time. At the time that the final
groundwater remedy is performed, EPA will determine whether the
MCLs and MEGs continue to be ARARs at the Site, whether ACLs
should be set, or whether a waiver of groundwater ARARs should be
granted'.
Federal Ambient Water Quality criteria (AWQC) are health and
environmental based criteria developed for carcinogens and non-
carcinogens. AWQC will be considered in monitoring on-site
streams.
3.
Location-Specific ARAR
Under the alternate remedy, all of the waste pits and lagoons
will be excavated. The two waste lagoons and many of the waste
pits lie within manmade wetland areas. These manmade wetlands
will be destroyed during the performance of this remedy. The
remedial action will comply with section 404 of the Clean Water
Act and with standards set by Maine requirements, including Maine
Freshwater Wetlands Act (38 M.R.S.A. Chapter 3, section 405-410)
and the Maine Hazardous Waste Management Rules (38 M.R.S.A. ~
1301 et seq., Chapters 800-802, 850, 851, 853-857), which govern
actions that take place in a wetland. The remedial action will
also comply with the Wetlands Executive Order (E.O. 11990) and
the Fish and Wildlife Coordination Act (16 U.S.C. ~ 661).
Following landfilling of the solidified wastes, EPA will create
compensatory wetlands to the extent required by federal and state
wetlands ARARs to reestablish wetlands that will be lost. during
remediation.
7
The remedial action will also comply with the Maine Water
Pollution Control Law: Solid Waste Disposal Areas~ Location (38
M.R.S.A., Chapter 3, article 2, section ~21). Under these
applicable regulations no boundary of a solid waste disposal area
shall lie closer than 300 feet to any classified body of surface
water. The design and construction of the landfill will be
performed in compliance with these regulations.
The remedial action will also comply with the Floodplain
Management Executive Order (E.O. 11988) and EPA regulation 40
C.F.R. Part 6, which implements the Executive Order. Although
approximately 30 acres of the Site lie within a 100-year
floodplain, none of the waste pits, lagoons, and contaminated
sediment areas lie within the floodplain. In 2c~ition, the RCRA
-------
ROD DECISION SUMMARY.
SACO TANNERY WASTE PITS SITE
Paqe 69. .
landfill to be constructed on-site will not be located within a
floodplain. Nevertheless, during construction activities, steps
will be taken to minimize any adverse impacts on the floodplains.
The remedial action will also comply with Maine Standards for
Classification of Minor Drainages (38 M.R.S.A. Chapter 3, ~ 468)
and Maine Alteration of Rivers, Streams, and Brooks (38 M.R.S.A.
Chapter 3, ~ 425 et sea.), which will prohibit the degradation of
stuart Brook, and Maine Standards for Classification of
Groundwater (38 M.R.S.A. Chapter 3, ~ 470), which will prohibit
the degradation of on-site groundwater. Finally, the remedial
action will comply with the Maine site Location Law (38 M.R.S.A.
Chapter 3, Section 481-490), which prohibits adverse impacts on
certain natural resources.
.C.
The Alternate Remedial Action is Cost Effective
The alternate remedial action is cost effective. Although the
cost. of the alternate remedy is substantially more than the cost
of the selected remedy, the alternate remedy will only become
effective in the event that the selected remedy cannot be
implemented, i.e., in the event that the State does not enact an
adequate state law converting the site property into a
conservation area within two years from the date that this ROD is
signed. In comparison to the cost of the other alternatives
considered at the site, and discussed in Section XI.C.,
Alternative SC-5 is more expensive than the cover alternative
(SC-3) and the other treatment and/or consolidation alternatives
(SC-4, SC-6, and SC-7). Nevertheless, SC-5 is also more
protective or technically feasible than any of these other
remedial alternatives. Finally, Alternative SC-5 is
substantially less expensive than the resource recovery
alternatives (SC-9 and SC-10) considered for the site.
D.
The Alternate Remedy utilizes Permanent Solutions and
Alternative Treatment or Resource Recovery Technologies
to the Maximum Extent Practicable
The alternate remedy utilizes permanent solutions and alternative
treatment technologies to the maximum extent practicable. The
alternate remedy will permanently address contamination contained
in the waste pits and lagoons. Excavated wastes will be
solidified and disposed of in a RCRA landfill to be constructed
on-site. The combination of excavation, treatment, and
landfilling in a RCRA landfill will provide a high degree of
permanence and protection against the threat of possible future
contaminant migration. In addition, the alternate remedy uses a
solidification process, which is an alternative treatment
-------
'--,
,
u
:j
ROD DECISION SUMMARY
. "
SACO TANNERY WASTE PITS SITE
Paae 70
The Alternate Remedy satisfies the Preference for
Treatment as a Principal Element
The alternate remedy includes treatment and thus satisfies the
preference for treatment. Under the alternate remedy, excavated
wastes will be solidified, or treated, prior to disposal in an
,on-site RCRA landfill. Treatment is a principal element of the
remediation.
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