Amended Record of Decision
(Enforcement Decision Document)
Remedial Alternative Selection
Western Processing Company, Inc.
Kent, Washington
DOCUMENTS REVIEWED
I am basing my decision primarily on the following documents
describing the analysis of the cost and effectiveness of remedial
alternatives for the Western Processing site.
Record of Decision and Summary of Remedial Alternative
Selection, dated September 25, 1985
Consent Decree
- Summary of Remedial Alternative Selection at the
Western Processing Company, Inc. site. Final Remedial
Action.
DESCRIPTION QJL SELECTED REMEDY
- Intensive soil and waste sampling on the Western
Processing property (Area I) and intensive soil sampling off
the property.
Selective excavation in Area I of highly contaminated
soils or non-soil materials ("specific wastes") before
groundwater pumping begins, with additional excavation
during and post-pumping if necessary. Off-site disposal of
excavated specific wastes. Exhume all buried containerized
wastes, with off-site disposal of all RCRA hazardous or
Ecology dangerous or extremely hazardous wastes. Excavate
or plug all utility and process lines in Area I.
After termination of groundwater pumping, cover Area I
with a RCRA consistent cap for closure of a land disposal
facility. Maintain cap for 30 years, unless period is
modified.
- Using the results of the soil sampling and analysis
program, eliminate direct contact threats in the non-Western
Processing property by excavation of all soils which exceed
the ADI level or the 1 x 10-5 excess cancer risk level or a
PCB concentration of 2 ppm, and by covering all remaining
surface soils with above background concentrations of any
contaminant. Maintain the covers for 30 years, unless the
period is modified for specific areas. Excavate utility
-------
lines leaving Area I and going towards Mill Creek, and
excavate or plug all other utility lines leaving Area I.
Clean utility manholes/vaults near the site. Dispose of
excavated material in Area I or in an approved off-site
disposal facility. Actions will be limited to those off-
property soils which may have been contaminated by Western
Processing. The lead contaminated house in Area 8 will be
decontaminated.
Construct and operate for a minimum of 5 to 7 years a
shallow groundwater extraction system which will achieve an
inward flow from the boundary of the currently contaminated
groundwater (except for a 50 foot setback along Mill Creek),
and which will permanently achieve Mill Creek performance
standards. Construct and operate for a minimum of 5 to 7
years a deeper groundwater extraction system which will,
while the extraction system is operating, provide for a
reversal of regional groundwater flow along the line of Mill
Creek or which will establish a hydraulic barrier to
regional groundwater flow along the line of Mill Creek.
Construct and operate an extraction system to permanently
reduce the concentration of trans 1,2-dichloroethylene in
the plume to less than 70 ppb. Construct, operate and
maintain or otherwise provide for a groundwater pre-
treatment plant. All extracted water leaving the site shall
comply with the requirements of Metro if discharged into the
sewer system or of Ecology if discharged into waters of the
state. Groundwater extracted from off-property areas may be
infiltrated onto Area I to assist in the leaching process.
- Construct, operate, and maintain a stormwater control
system.
- ^ Excavate contaminated Mill Creek and east drain
sediments which may have been affected by Western
Processing.
- Intensive monitoring of Mill Creek, the east drain,
groundwater and the groundwater extraction system
performance. Demonstrate compliance with the Mill Creek and
trans 1,2-dichloroethylene performance standards for 30
years from the termination of pumping, unless modified.
- Perform conditionally required actions if the
performance standards are not achieved, or if it appears
that more than 20 years of groundwater extraction will be
necessary^ These studies may require tests (bench-scale or
pilot scale) of potential remedial techniques.
DECLARATIONS
Consistent with the Comprehensive Environmental Response
-------
Compensation, and Liability Act of 1980 (CERCLA), and the
National Contingency Plan (40 CFR Part 300), I have determined
that the above Description of Selected Remedy at the Western
Processing site is a cost-effective remedy that provide adequate
protection of public health, welfare and the environment. The
State of Washington has been consulted and agrees with the
selected remedy. Settlements have been reached between the
governments (EPA and the State) and the responsible parties based
on the selected remedy.
I have also determined that the action being taken is a
cost-effective alternative when compared to the other remedial
options reviewed. In addition, the off-site transport, storage,
destruction, treatment, and secure disposal is more cost-
effective than other remedial actions, and is necessary to
protect public health, welfare or the environment. All off-site
disposal shall be in compliance with the policies stated in Jack
W. McGraw, Action Assistant Administrator, Office of Solid Waste
and Emergency Response's May 6, 1985 memorandum entitled
Procedures for Planning and Implementing Off-site Response
Actions,, and any amendments or supplements thereto.
If additional remedial actions are determined to be
necessary, a Record of Decision or Enforcement Decision Document
will be prepared for approval of the future remedial action.
Date Regional Administrated
-------
9/2/86
Summary of Remedial Alternative Selection at the
Western Processing Company, Inc. site,
Kent, Washington
Final Remedial Action
INTRODUCTION
The initial Record of Decision (ROD) for the Second Operable
Unit at the Western Processing Superfund Site in Kent, Washington
was signed by the Regional Administrator on September 25, 1985.
Since then, two major actions have occurred which affect the the
original ROD. First, the results from the Summer 1985
groundwater field work were received by EPA in October 1985 and
later summarized by CH2M Hill in a Supplemental Remedial
Investigation (SRI) report dated July 1986. Second, negotiations
with the potentially responsible parties (PRPs) concluded with
approximately 180 parties signing the Phase II consent decree.
The remedial action will now be undertaken by the consenting
defendants rather than the government, and will be a final
remedial action. Most of the September 1985 ROD is still
relevant and appropriate. The purpose of this amended summary
for the second operable unit is to document the changes the new
information and new circumstance have had on the selection of the
remedy. This amended ROD is essentially an Enforcement Decision
Document (EDD) as it is documenting the results of successful
negotiations.
In the months since the ROD was signed, a convention has
been established when identifying the Western Processing
Superfund site and its component areas. The word "property" or
"on-property" is used to describe the property owned by Western
Processing where business operations occurred, and is synonymous
with Area I. (See Figure 1.) (Area VII is also owned by Western
Processing, but was used for a residence.) The word "site" is
used to describe Area I and the areas designated by Roman
numerals in Figure 1 in proximity to Area I (but excluding Area
VI.) The boundaries of these numbered areas are considered
approximate and may change if soil contamination is detected
beyond the current boundaries. The word "off-property" is used
to describe the entire site except Area I. Also, the word
"governments" means EPA and the Washington Department of Ecology
(Ecology).
SITE LOCATION AND DESCRIPTION
This section is unchanged.
SITE HISTORY
This section is unchanged, except that the major events
described above have occurred in the past year. The PRPs have
-------
continued the stormwater collection and treatment on the Western
Processing property.
CURRENT SITE STATUS
The September 1985 ROD states that 13 additional groundwater
monitoring wells were drilled in July and August 1985 to the west
of the Western Processing property. These 13 wells plus 10
existing monitoring wells were sampled to determine whether the
1,2 trans-dichloroethylene detected in Well 35 had originated at
Western Processing. (See Figure 2.) Prior to this investigation,
EPA's consultants considered it unlikely that this contamination
had migrated to Well 35 from Area I because Mill Creek appeared
to act as a hydraulic barrier to near-surface groundwater flow.
Chemical data from the Supplemental Remedial Investigation
(SRI) sampling of these new and previously installed monitoring
wells indicate a plume of trans-l,2-dichloroethylene (and lesser
amounts of trichloroethene and tetrachloroethene) is emanating
from the vicinity of well 21 on the Western Processing property
and is migrating northwest both into and beneath the creek.
Contaminants have been detected as far west as well 35. The
maximum groundwater concentration of trans 1,2-dichloroethylene
detected in Well 35 has been 900 ppb. The area around Well 21 has
been determined to be the source. The maximum concentration in
Well 21 has been 380,000 ppb. The concentration decreases in the
downgradient direction. The next highest concentrations have
been found east of Mill Creek within the top 40 feet (area of
upward vertical migration into the creek). Only traces of
contaminants have been detected at depths below 80 feet on the
east side of Mill Creek.
There are two major transport mechanisms that could possibly
carry contaminants from near the surface in the vicinity of well
21 to the depths necessary for the contaminant to flow beneath
Mill Creek: (1) downward vertical groundwater flow or (2) pure
contaminant density flow. Because of the extremely steep
vertical descent of the contaminant and the general upward
groundwater gradient, the most probable mechanism is density
flow. Downgradient of the Well 45 cluster, the contaminant plume
has apparently migrated in a sand zone that underlies a clay/silt
layer at approximately 40 feet. This sand layer can be traced
laterally as far as well 42 at depths of approximately 40 to 80
feet, though contaminants have not been detected that far from
Area I.
While the SRI study showed that the trans - 1,2
dichloroethylene in well 35 most likely did originate at the
Western Processing property, other, key aspects of the generalized
hydraulic conceptual model were' confirmed. The capture depth
effect of Mill Creek was confirmed to extend to approximately
this same sand layer at approximately 40 feet (upward flow
-------
gradients), followed by a level of predominantly horizontal flow,
then, at the below 60 feet level, downward hydraulic flow.
Groundwater flow directions are to the northwest.
The other sections of the Current Site Status section are
unchanged.
ENFORCEMENT
Negotiations with the potentially responsible parties (PRPs)
concluded in May 1986 with approximately twenty PRPs signing a
stipulation. This stipulation gave EPA sufficient moneys (when
combined with previously committed State moneys) to have the
Corps of Engineers conclude negotiations for a Corps supervised
remedial design contract, while also giving the PRPs additional
time to decide whether they wish to sign the consent decree. The
remedial design contract was not initiated when, on July 2, 1986,
over 120 PRPs submitted their signatures to the governments. By
the end of July over 180 PRPs had signed the consent decree.
(These 180 consenting defendants are not necessarily the same
PRPs that signed the Phase I consent decree.) The governments
may sue a number of the non-settling PRPs for all remaining
relief.
COMMUNITY RELATIONS
Community relations activities have continued since the
September 1985 ROD, primarily thru informal briefings and phone
updates. The proposed Fund-financed remedy and the dioxin
detoxification (a Phase I consent decree issue) were the subjects
of Kent City Council briefings. No new major issues have been
raised. The lawsuit between a neighboring property owner and a
number of PRPs is still underway.
The public comment on this amended ROD and summary will run
simultaneously with the Department of Justice comment period on
the consent decree. The governments' responses to the issues
raised will be submitted to the court, as well as being available
to the public.
RECOMMENDED ALTERNATIVE
The recommended alternative is the remedy which has been
negotiated with consenting defendants. This remedy is described
primarily in Appendix B of the Phase II Consent Decree (consent
decree.) Appendix B is entitled "Scope of Work for Addressing
Soil and Groundwater Contamination at and Emanating from the
Western Processing site."
For the most part, the consent decree remedy is either
identical to, or substantially the same as, the alternative
selected in the original September 1985 ROD. (See Table 1.)
-------
The differences between the remedy in the consent decree and the
September 1985 ROD fall into 3 classes:
1. The actions had been foreseen as part of the remedy
outlined in the ROD, but were expected to occur after the first 5
to 7 years of remedial action. (The September 1985 ROD selected
an interim remedy.) These "Future Actions" included a RCRA
compliant cap, long-term O&M, and long-term groundwater and
surface water monitoring. The future actions are now part of the
selected remedy in the consent decree.
2. The original purpose of the remedy in the
September 1985 ROD is still achieved, but the schedule or phasing
or approach is different. In some of these situations, the
selected remedy in the consent decree is more specific where the
ROD was more general. These changes alone would generally not
have required the September 1985 ROD to be amended. Examples of
these include the on-property soil excavation and the allowable
concentrations in Mill Creek; and
3. Further actions were to be planned if they became
necessary because of new regional groundwater data. Because the
new information confirmed regional groundwater contamination by
trans 1,2, dichloroethylene, remedial actions and possible still
further future actions have been added to remedy this situation.
Therefore, the following components are proposed for the
remedial action. These include most of the elements of the
September 1985 ROD.
- Intensive soil and waste sampling on Area I and
intensive soil sampling off the property.
- Selective excavation in Area I of highly contaminated
soils or non-soil materials ("specific waste") before
groundwater pumping begins, with additional excavation
during and post-pumping if necessary. Off-site disposal of
excavated specific wastes. Exhume all buried containerized
wastes, with off-site disposal of all RCRA hazardous or
Ecology dangerous or extremely hazardous wastes. Excavate
or plug all utility and process lines in Area I.
After termination of groundwater pumping, cover Area I
with a RCRA consistent cap for closure of a land disposal
facility. Maintain cap for 30 years, unless period is
modified.
- Using the results of the soil sampling and analysis
program, eliminate direct contact threats in the non-Western
Processing property by excavation of all soils which exceed
the ADI level or the 1 x 10-5 excess cancer risk level or a
PCB concentration of 2 ppm, and by covering all remaining
surface soils with above background concentrations of any
contaminant. Maintain the covers for 30 years, unless the
period is modified for specific areas. Excavate utility
-------
lines leaving Area I and going towards Mill Creek, and
excavate or plug all other utility lines leaving Area I.
Clean utility manholes/vaults near the site. Dispose
excavated material in Area I or in an approved off-site
disposal facility. Actions will be limited to those off-
property soils which may have been contaminated by Western
Processing. The lead contaminated house in Area 8 will be
decontaminated.
- Construct and operate for a minimum of 5 to 7 years a
shallow groundwater extraction system which will achieve an
inward flow from the boundaries of the area depicted in
Figure 3, and which will permanently achieve Mill Creek
performance standards. Construct and operate for a minimum
of 5 to 7 years a deeper groundwater extraction system which
will, while the extraction system is operating, provide for
a reversal of regional groundwater flow along the line of
Mill Creek or which will establish a hydraulic barrier to
regional groundwater flow along the line of Mill Creek.
Construct and operate an extraction system to permanently
reduce the concentration of trans 1,2 dichloroethylene in
the plume to less than 70 ppb. Construct, operate and
maintain or otherwise provide for a groundwater pre-
treatmeht plant. All extracted water leaving the site shall
comply with the requirements of Metro if discharged into the
sewer system or of Ecology if discharged into waters of the
state. Groundw.ater extracted from off-property areas may be
infiltrated onto Area I to assist in the leaching process.
- Construct, operate, and maintain a stormwater control
system.
- Excavate contaminated Mill Creek and east drain
sediments which may have been affected by Western
Processing.
- Monitor intensively Mill Creek, the east drain,
groundwater and the groundwater extraction system
performance. Demonstrate compliance with the Mill Creek and
trans 1,2-dichloroethylene performance standards for 30
years from the termination of pumping, unless modified.
Perform conditionally required actions if the
performance standards are not achieved, or if it appears
that more than 20 years of groundwater extraction will be
necessary. These studies may require tests (bench-scale or
pilot scale) of potential remedial techniques.
Where the proposed actions are different from the September
1985 ROD, the proposed actions should be considered additional
alternatives to those alternatives previously evaluated in the
Feasibility Study and the 1985 ROD.
-------
This remedy is designed to be a final operable unit.
However, additional actions may be necessary under certain
circumstances. First, if the selected remedy is unsuccessful in
meeting the performance standards, new or different technologies,
such as in-situ soil stabilization, may be considered and
addressed in an additional amended ROD after the consenting
defendants request Government approval of such treatments.
Second, remedies of deep (regional) groundwater contamination
discovered by the monitoring well network (with exception of the
trans 1,2 dichloroethylene involving Well 35) is not covered by
the remedial actions. However, it is also not included in the
releases being given to the consenting defendants. The consent
decree specifically states that the consenting defendants and the
governments shall enter negotiations if any plume suspected as
originating at Western Processing is found west of Mill Creek.
A further discussion of the recommended alternative follows.
Where the recommended alternative is identical to or similar to
the September 1985 ROD, no discussion is repeated in this
document. Where the recommended alternative is different than
the alternative in the September 1985 ROD, an explanation is
given. The change may be justified by significant new
information, consideration of cost-effectiveness; adequate
protection of public health, welfare, and the environment; or
compliance with other applicable or relevant environmental
standards.
On-prooerty (Area H Soils
The recommended alternative for Area I soils is identical
to the alternative in the September 1985 ROD except for:
Dspecific waste excavation criteria and timing; 2) containerized
waste disposal; and 3) RCRA compliant cap and maintenance.
The September 1985 ROD stated that the results of a testing
and sampling program would define the selective excavation of
highly contaminated (non-containerized) soil and non-soil
material. The purpose of the excavation was to reduce the source
strength, but no criteria was specified. The cost-estimate was
based on excavating and disposing off-site 10,650 cubic yards,
but the ROD went on to say that the quantity (and thus the cost)
could not be accurately determined until the sampling is
completed.
The proposed remedy continues to base the selection of the
material to be excavated on the results of an Area I soil and
waste sampling and analysis program. The primary difference is
that the consent decree specifies the criteria which should be
used to select the most troublesome source material. The
criteria include 1) the contaminants may not be cost-effectively
removed by in-situ leaching and which could, by their presence,
-------
prevent compliance with the Mill Creek water quality performance
standards; or 2) the contaminants may, because of their location
or physical or chemical properties, migrate beyond the
hydrogeologic boundary of Mill Creek; or 3) the material may
adversely affect the stability of a cap over Area I. The
secondary difference is that the consenting defendants are
required to remove 10,000 cubic yards prior to pumping. The
Governments may require additional excavation at any time if
compliance with Mill Creek standards or the stability of the cap
is at risk.
The September 1985 ROD assumes that all exhumed drums and
other containerized materials would be disposed off-site in an
approved facility. The proposed remedy will require off-site
disposal of all RCRA hazardous wastes and Ecology dangerous or
extremely hazardous wastes. However, if the exhumed
containerized material is not hazardous, the material may be
replaced into Area I under the clean cover and eventual RCRA cap.
All of the above changes are consistent with the original
purpose of the Area I excavation. However, these changes will
the remedy more cost-effective while maintaining the same public
health and environmental protections as the original remedy.
The third change is the addition of a cap consistent, with
the criteria in the RCRA regulations for closure of a land
disposal facility (landfill) in effect at the time of entry of
the consent decree. The September 1985 ROD envisioned site
close-out to include such a cap. Also, compliance with other
environmental laws and standards require that such a cap be
placed over Area I as some hazardous wastes will be left on site.
The 1985 Feasibility Study estimated that the cost of the cap
would be approximately $2,900,000. The cap maintenance
provisions are also consistent with RCRA.
Off-Property Soils and Issues
The recommended alternative for the off-property soils is
identical to the alternative in the September 1985 ROD except the
period of maintenance for the cover is specified. Both
alternatives require that soils contaminated with above
background concentrations of contaminants which may have come
from Western Processing activities be covered. This cover may be
soil or asphalt but must have a permeability less than or equal
to the permeability of the subsoil. The September 1985 ROD
acknowledges that the cover will have to be maintained for a
minimum of 30 years, but the selected remedy covered by that ROD
covered only the first 5 years. The consent decree requires the
consenting defendants provide foj: the maintenance of the cover
for a period of 30 years. This requirement may be modified for
specific off-property areas if, for example, the property owner
develops or paves a parcel for his own benefit or use.
-------
The other proposed off-property actions for direct contact
hazards (cleaning the lead contaminated house in Area 8 and
inspection and cleaning utility vaults) are also unchanged from
the September 1985 ROD.
Selection of Disposal Facility
The proposed alternative is virtually identical with the
September 1985 ROD. Both alternatives involve both Area I and
off-site disposal. Government approval for the use of any
particular off-site facility will still be based on the
requirements specified in the Hay 6, 1985 memorandum entitled
"Procedures for Planning and Implementing Off-Site Response
Actions" from Jack W. McGraw, EPA Acting Assistant Administrator
for Solid Waste and Emergency Response, or any amendments or
supplements. If, however, government approved facilities in
Region 10 are unavailable, a variety of steps must be taken by
the consenting defendants, including consideration of temporary
storage and consideration of government approved disposal
facilities in Regions 8 and 9. If all these options are out of
the question, the consenting defendants and the government will
negotiate to develop an acceptable alternative. The alternatives
to be considered would include treatment and destruction. If the
selected remedial action is anything other than disposal at a
government approved hazardous waste facility, a public comment
period and an amended ROD may be necessary.
Shallow Groundwater
The shallow groundwater proposed actions in the consent
decree are largely similar to the selected actions in the
September 1985 ROD. To ensure that there will be no degradation
of the shallow groundwater beyond the currently contaminated
zone, the consenting defendants will be required, throughout the
pumping period, to achieve a shallow groundwater flow inward from
the boundaries of the contaminated zone. (See Figure 3.)
Compliance with this performance standard will be monitored by
checking the water levels in new and existing monitoring wells.
An exception has been added for a 50 foot set-back from Mill
Creek to avoid drying up the creek. This change is more cost-
effective and protective of the environment.
Mill Creek performance standards (see below) must also be met
during and after pumping. A demonstration that the Mill Creek
performance standards will be met on a permanent basis after
ceasing pumping is the key criteria for determining when the
shallow groundwater pumping may terminate. This criteria for
determining when groundwater extraction may cease is consistent
with the September 1985 ROD. The September 1985 ROD included a
period of five years of pumping, to be followed by a major
reassessment of this activity. The consent decree's minimum
-------
pumping period of 5 to 7 years will provide a large degree of
improvement in the shallow groundwater quality , particularly in
the more mobile organics.
The selected remedy in the September 1985 ROD allowed low
capital cost in-situ chemical leaching techniques to be used
after monitoring the site to ensure that adequate gradient
control had been established and after sufficient laboratory
scale testing. These techniques may also be applied by the
consenting defendants under the consent decree after they
specifically ask for and receive the governments' permission.
The consenting defendants may also ask for permission to apply
other techniques which may become more feasible in the future,
such as in situ solidification, but a more detailed review,
including public comment and an amended ROD, would be necessary
prior to the governments' approval.
Regional Groundwater
The September 1985 ROD stated that additional remedial
activities may be required to complete the site response if
contamination from Western Processing is found in the regional
aquifer. The proposed alternative addresses regional groundwater
contamination in 4 ways: 1) clean-up of the only known plume; 2)
reverse regional groundwater flow along approximately 1800 feet
of Mill Creek, or establish an hydraulic barrier to regional
groundwater flow along the same line; 3) extensive regional
groundwater monitoring; and 4) groundwater use restrictions.
The consent decree requires that the concentration of trans
1,2-dichloroethylene be reduced to below 70 ppb throughout the
plume prior to termination of the groundwater extraction system
for this portion of the clean-up. The proposed Recommended
Maximum Concentration Limit in drinking water (50 FR 4688,
November 13, 1985) for trans 1,2-dichloroethylene is 70 ppb.
While no one is currently using or drinking this groundwater,
this proposed drinking water criteria is the relevant environment
standard. This level of clean-up is to be achieved by source
removal from Area I during the specific waste removal and by
installing wells specifically placed and designed to extract the
trans 1,2-dichloroethylene already beyond the boundary of Area I.
The requirement to reverse groundwater flow at a depth of 40
to 70 feet at approximately Mill Creek, or to establish an
hydraulic barrier to the regional groundwater flow at
approximately the same location, will insure that no new regional
groundwater plumes will escape from Area I and pass under Mill
Creek. In addition, the extraction wells in the regional
groundwater may provide for earlier and easier detection of any
plume which has bypassed the creek and the existing monitoring
net. These steps are necessary to protect the groundwater for
future use. They are also cost-effective as it is less expensive
-------
to clean-up a smaller area of groundwater contamination than to
clean-up a large plume. The groundwater flow reversal would
probably be achieved by placing extraction wells screened at the
50 to 70 foot depth within Areas I and IX. The hydraulic barrier
would be achieved by placing extraction wells very near the
creek, including the west side of the creek.
The consent decree also does not give the consenting
defendants any release of liability for regional groundwater
contamination except for their clean-up of the only known plume.
If further regional groundwater contamination is ever detected,
all PRPs may be held liable and required to remedy the situation
and/or repay the governments' costs.
Discharge of Extracted Groundwater
The cost estimates in the September 1985 ROD assumes that
all extracted groundwater would be pre-treated and discharged to
the Metro sewer and treatment system. This is still the most
likely disposal option for all groundwater extracted from Area I
or any other highly contaminated area. The proposed alternative
expands the disposal options for the uncontaminated or only
slightly contaminated groundwater which may be extracted as part
of the regional or even shallow off-property groundwater
extraction system. These additional options are discharge into
a surface water body in compliance with the requirements of
Ecology pursuant to the NPDES system, or infiltration into Area I
to assist the leaching process. These alternatives were raised
when it was realized that the quantity of water that may be
produced from the newly required regional groundwater actions may
exceed the capacity of the local sewer system. These changes are
consistent with applicable and relevant environmental standards
and criteria. For uncontaminated or slightly contaminated water,
these alternatives may be more cost-effective than discharge to
Metro. Infiltration of stormwater into Area I prior to cap
placement to aid the leaching program was the recommended
stormwater alternative in the September 1985 ROD. Infiltration
of groundwater prior to cap placement to also aid the leaching
program is a extension of the same idea.
Creek
The objectives for remedial action in Mill Creek are still
the objectives in the September 1985 ROD. The objectives will
still be met by groundwater control, shallow groundwater quality
improvement (from specific waste excavation, leaching,- and
groundwater extraction), and sediment excavation.
As a result of negotiations, .numerical performance standards
for water quality in Mill Creek were developed. (Table 2.) These
numerical performance standards are consistent with the approach
described in the September 1985 ROD. The calculation of the
-------
maximum allowable downstream concentration for each pollutant
considers both the ambient water quality criteria for aquatic
organisms and the upstream (background) concentration. As
Ecology's long-term goals of improving upstream water quality are
achieved, the consenting defendants will be required to meet more
rigorous Mill Creek performance standards.
As in the September 1985 ROD, the shallow groundwater
concentrations which will allow these Mill Creek performance
standards to be permanently achieved will require over 99% of the
available (mobile) zinc and and a high percentage of the
available (mobile) cadmium to be removed from the site.
The recommended alternative still includes the Mill Creek
and east drain sediment testing and excavation program. The
minimum reach which will be tested has been slightly shortened at
the downstream end, but will still include 300 feet downstream of
the east drain discharge into Mill Creek.
Stormwater controls
The recommended stormwater remedial actions are unchanged.
Monitoring
The recommended monitoring program is unchanged. The
consenting defendants are required to continue the extensive
monitoring program for at least 30 years from the cessation of
pumping to demonstrate full compliance with the consent decree.
Land and Groundwater Use Restrictions
The consent decree requires the consenting defendants to use
their best efforts to place groundwater, and, in the case of Area
I, land use restrictions in the county property records. The
September 1985 ROD foresaw the need for such restrictions. The
land use restriction on Area I follows the wording in the RCRA
regulations at 40 CFR 264.120 and 264.117(c) and states that
post-remedial action land use is restricted such that use of the
property must never be allowed to disturb the integrity of the
final cover, or any other component of any containment system, or
the function of the monitoring system.
The groundwater use restrictions will also be placed in the
county property records. The groundwater restrictions will
ensure that there will be no threats to public health from any
contaminated groundwater.
-------
Community Relations
Proposed community relations activities are unchanged from
the September 1986 ROD. The governments will maintain the lead
for the community relations activities, but the consent decree
outlines activities where the consenting defendants and their
contractors will cooperate with the governments' activities.
Other Issues
Floodplain protection is unchanged from the September 1985
ROD.
Costs
No cost breakdowns are available. The consenting defendants
have estimated that the cost of the remedy is approximately
$40,000,000. This cost estimate is consistent with the cost
estimates in the September 1986 ROD.
CONSISTENCY WITH OTHER ENVIRONMENTAL LAWS
The list of federal and state applicable and relevant
environmental standards, criteria, guidance, and advisories are
unchanged from the September 1985 ROD.
The recommended alternative is currently considered a final
remedy. However, as summarized under Future Actions, items which
are currently unknown may require future evaluation and actions.
Aspects of the recommended alternative which are consistent
with the applicable and relevant portions of RCRA regulations
include:
- A cap over Area I designed to be consistent with RCRA
regulations for closure of a land disposal facility, and
maintenance of this cap.
The off-site soil cover design and maintenance
- Groundwater monitoring
Land and groundwater use restrictions in Area I and
other areas
The recommended alternative is still consistent with the
Assistant Administrator's application of RCRA to the Crystal
Chemical CERCLA site. The federal Water Quality Criteria for
aquatic organisms are still used to set Hill Creek performance
standards, but a factor has been added to reflect the variable
quality of the upstream (background) water quality. The
performance standard for the trans 1,2-dichloroethylene is
-------
consistent with the RMCL proposed under the Safe Drinking Water
Act. All other elements are consistent with the statements in
the September 1985 ROD.
Ecology has been an active participant in the negotiations
and supports the remedy described in the consent decree and this
amended ROD summary.
OPERATION AND MAINTENANCE (O&M)
The O&M activities required to ensure effectiveness of the
remedy include:
Operation of the groundwater extraction and treatment
systems as long as necessary
Maintenance of the RCRA cap, off property covers, and the
stormwater control system for 30 years
Long-term monitoring of the shallow and deep groundwater and
Mill Creek, including 30 years of monitoring after
termination of groundwater extraction
All O&M activities will be the responsibility of the
consenting dependents.
SCHEDULE
- Soil and waste sampling program
stipulation filed August 15, 1986
- Soil and waste sampling September to November
1986
- Consent decree lodged September 1986
- Detailed work plans received
from the consenting defendant's
contractor February 1987
- Start construction Spring-Summer 1987
- Start groundwater extraction 1988
FUTURE ACTIONS
No future actions are presently expected. However as
discussed above, mechanisms are in place for initiating new or
revised actions if they are necessary. Areas were additional
actions may be necessary include: '
- Regional groundwater if another plume is detected.
-------
New technologies for soil stabilization or treatment
that may arise as a result of conditionally required
actions, application of the McGraw policy, or at the request
of the consenting dependents.
-------
FIGURE 1
-------
RAILROAD
=±tt
~\
±t±
-HH
-H+-
FENCE LINE—^
^
WESTERN PROCESSING
SITE
JITC
VACANT HOUSES
MW-53
MW-54@S)@MW-52 \DW-34 S.D.
MW-47-
MW-48®|xU§'UW-45
T) MW-46
r^
s*
MV
MW-50
MW-5I®S)®MW-49V
SOUTH 196lh SI.
^
1
1
INDUSTRIAL PARK
LEGEND: ' (
0 SluNo.
9> Wellt Inttilltd end Sampled During Summer 1985
O Exiiting Welli Sampled During Auguit 1985
G
& Exiiting Well Abandoned
OMW-35
>
T>
C
CM
f.
Scale: 0
200
100
F10ur*2
-------
Area of Inward Shallow
Groundwater Flow
50 ft. Buffer
from Mill Creek
FIGURE 3
-------
TABLE 1
MAIN ELEMENTS QF THE CONSENT DECREE SELECTED REMEDY
Similar Different
to from
September 1985 September 1985
ROD ROD
General Requirements
Health and Safety Plan
Quality control/quality
assurance plan for samples
and analysis
Selection of Off-site disposal
facility
Floodplain protection
Area I stormwater system
Area J. Soils
Non-destructive subsurface
geophysical survey
Soil/waste sampling and
analysis program
Excavate containerized wastes
Excavate specific wastes
Excavate and dispose off-site
all PCB's over 50 ppm
Plug or excavate utilities
Control stormwater runoff
Clean fill for a work surface
RCRA cap and maintenance
Off-Property Soils and Issues
Soil sampling and analysis
program
Non-destructive geophysical
survey
Excavate hots spots over ADI
or over 10-5 excess cancer
risk or PCB's over 2 ppm if
contamination may have been
from Western Processing
Cover soils with concentrations
over background if contamina-
tion may have been from
Western Processing
Always required
Always required
X
X
X
X
X
X
X
X
X
X
X
X (2)*
X (2)
X (1)
-------
Non-extremely hazardous waste
may be brought onto Area I X
and placed under the cap
Maintain cover X (1)
Clean the house in Area VIII X
Test and clean live utilities X
Groundwater and Mill Creek
Specific Actions
Shallow groundwater extraction
from the contaminated X (2)
on and off-property areas
Regional groundwater extraction
wells for trans-1,2 dichloro-
ethylene extraction, and to X (3)
reverse the flow or to esta-
blish a hydaulic barrier
Discharge groundwater to:
Metro X
Surface water X (2)
Area I infiltration X (2)
Minimum 5-7 years of pumping X (2)
In-situ enhanced leaching X
Monitoring programs X
30 year post-pumping compliance
period X (1)
Groundwater use restrictions X (1)
Excavate and restore Mill Creek
and the east drain X (2)
Performance Criteria to Cease Pumping
Achieve Mill Creek performance
standards for aquatic organisms X (2)
Reduce trans 1,2-dichloroethylene
to 70 ppb throughout the plume X (3)
Other Issues
On-going Community Relations
Activities X
Deed/title restrictions X (1)
-------
* (1) The actions had been foreseen as part of the remedy in
the September 1985 ROD, but were planned to occur after the first
5 to 7 years of remedial action which were covered by that ROD.
(2) The concepts and final criteria or protection are
similar to the selected remedy in the September 1985 ROD, but the
approach or phasing is different.
(3) Because regional groundwater contamination by trans 1,2
dichloroethelene from Western Processing has been confirmed, new
elements are being added to the selected remedy.
-------
TABLE 2.
MILL CREEK PERFORMANCE STANDARDS
Consent Decree, Appendix B
Section IV. D. 4. Allowable Concentrations in Mill Creek
a. If the concentration of a Mill Creek indicator
chemical or other priority pollutant at the upstream (background)
monitoring point in Mill Creek is less than two-thirds of the
applicable upstream Federal Ambient Water Quality Criterion for
Aquatic Organisms (Water Quality Criterion), the maximum
allowable concentration at the downstream compliance point shall
be the downstream Water Quality Criterion.
b. If a Water Quality Criterion is not achievable
because the upstream (background) concentration of a chemical is
near or above the Water Quality Criterion, the maximum allowable
concentration at the downstream compliance point shall be the
level described below:
(i) If the concentration of a Mill Creek
indicator chemical or other priority pollutant at the upstream
(background) monitoring point in Mill Creek is at or above two-
thirds of the upstream Water Quality Criterion, the maximum
allowable concentration at the downstream compliance point shall
be no more than the background concentration plus fifty percent
of the background concentration; or
(ii) If the concentration of a Mill Creek
indicator chemical or other priority pollutant at the upstream
(background) monitoring point in Mill Creek is at or above the
upstream Water Quality Criterion, the maximum allowable
concentration at the downstream compliance point shall be no
greater than background plus eighty percent of the upstream WAter
Quality Criterion.
The applicable Water Quality Criteria shall be those final
criteria published in the Federal Register as of the date of
entry of this Consent Decree.
------- |