United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R10-88/014
July 1988
SEPA
Superfund
Record of Decision
Frontier Hard Chrome, WA
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30277-101
^REPORT DOCUMENTATION
PAGE
I. REPORT NO.
EPA/ROD/R10-85/014
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
Frontier Hard Chrome, WA
Remedial Action - Final
3. Recipient's Accession No.
S. Report Date
07/05/88
8. Performing Organization Rept. No.
9. Performing Organization Name and Address
10. Project/Task/Work Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/000
14.
IS. Supplementary Note*
16. Abstract (Umit: 200 words)
The Frontier Hard Chrome (FHC) site, covering approximately one-half acre, is located
in the City of Vancouver, Washington. The areal ground water is used as the drinking
water supply for.the City of Vancouver, which has two well fields within one mile of'the
site. Since 1955, the site.has primarily been .occupied by two companies engaged in the
chrome plating business. Pioneer Plating operated ,at the site from 1958 to 1970. The
site was then occupied by FHC until 1983. Presently, the facility is being used as a
rage and staging area for a neighboring business. During the operation of Pioneer
the initial operation of FHC, chromium plating wastes were discharged to the
sanitary sewer system. In 1975, the City of Vancouver determined that the chromium in
the wastewater from FHC was upsetting the operation of its new secondary treatment
system. FHC was directed by the City and the Washington Department of Ecology (Ecology)
to cease discharge, to the sewer system until a treatment system was installed to remove
the chromium waste. At that time, FHC began discharge of their untreated plating wastes
to a dry well behind the facility. In 1976, Ecology permitted FHC to discharge to the
dry well. Additionally, the permit contained a schedule for completion of a waste
treatment system. Between 1976 and 1981, several extensions of the permit and schedule
were granted, as the deadlines passed without compliance. In 1982, Ecology found FHC in
(See Attached Sheet)
17. Document Analysis a. Descriptors
Record of Decision
Frontier Hard Chrome, WA
First Remedial Action - Final
Contaminated Media: gw
Key.Contaminants: chromium
b. tdenttfiers/Open-Ended Terms
c. COSATI Field/Group
inability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
31
22. Price
(SeeANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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EPA/ROD/R10-85/014
fcntier Hard Chrome, WA
West Remedial Action - Final
16. ABSTRACT (continued)
violation of the Washington State Dangerous Waste Act for the illegal disposal of
hazardous wastes, and in 1983 ordered FHC to stop discharging to the dry well. As a
result, FHC also was required to prepare a plan for the investigation of the ground
water. FHC closed down all operations at the site. The company did not undertake the
investigation. In December 1987, EPA published a ROD for the site's first operable
unit, which addressed the soil contamination. This second and final operable unit
addresses chromium contaminated ground water.
The selected remedial action for this site includes: ground water pump and treatment
using selective media ion exchange to remove chromium, followed by carbon adsorption to
remove VOCs with discharge into the river or the city sanitary sewer; ground water
monitoring; and implementation of institutional controls to restrict ground water usage
and to control new well drilling. The estimated present worth cost for this remedy is
£3,800,000.
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RECORD OF DECISION
DECLARATION
SITE NAME AND LOCATION
Frontier Hard Chrome Site
Vancouver, Washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the
Frontier Hard Chrome site in Vancouver, Washington, developed in accordance
with the Comprehensive Environmental Response, Compensation, and Liability Act
of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization
Act of 1986 (SARA), and, to the extent practicable, the National Contingency
Plan. This decision is based on the administrative record for this site. The
attached index identifies the items which comprise the administrative record
upon which the selection of the remedial action is based.
The state of Washington has concurred verbally on the selected remedy.
DESCRIPTION OF THE REMEDY
This decision document, addressing contaminated groundwater, represents
the second of two operable units for the site. The selected remedy for this
operable unit is to pump and treat groundwater from the area of greatest
contamination and to prevent anyone from using contaminated groundwater until
concentrations are reduced to drinking water standards. The first operable
unit at this site covered stabilization of contaminated soils.
The major components of the selected remedy include the following:
A series of extraction wells to pump groundwater from the area of
greatest contamination (defined as levels of chromium greater than
50 ppm). •
A treatment system for removal of chromium and organic solvents from
the extracted groundwater to a level that would protect aquatic life
in the Columbia River or be accepted for discharge to the city
sanitary sewer.
Discharging the treated water into the Columbia River or into the
city of Vancouver sewer system. The Remedial Design will determine
which method is cost effective.
Developing regulatory controls to restrict the use of the groundwater
and to control the drilling of new wells in the plume of chromium
contamination.
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DECLARATION
The selected remedy is protective of human health and the environment,'
attains federal and state requirements that are applicable or relevant and
appropriate to this remedial action, and is cost effective. This remedy
satisfies the statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume as a principal element and utilizes
permanent solutions and alternative treatment (or resource recovery)
technologies to the maximum extent practicable.
Because this remedy will result in hazardous substances remaining on site
above health-based levels, a review will be conducted^ with in five years after
commencement of remedial action to ensure that the r&medy continues ttf provide
adequate protection of human health aiwr the envji'ronmei
Date
Robie G. RusseTT
Regional Administrator
U.S. Environmental Protection Agency
Region 10
\,
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3 •
Index
The administrative record upon which this Record of Decision (ROD) is based
contains the following items in addition to the index to the administrative
record for the first ROD for the site signed December 30, 1987.
Ti tie or Description
Ecology Recommendation
for Record of Decision
(Part 2) for Frontier
Hard Chrome
ROD Number Two for
Frontier Hard Chrome-
delegation briefing
Record of Decision
for Frontier Hard
Chrome-Soils/Source
Control
Synopsis of briefing
for local officials
City of Vancouver
comments on RI/FS
Transcript of Public
Hearing
Frontier Hard Chrome
Fact Sheet
Site Visit Frontier
Hard Chrome
Frontier Hard Chrome
Institutional Controls
FHC Institutional
Controls
FHC Institutional
Controls
Date
#Pqs Author
April 5, 1988 15 Mike Gallagher-
Ecology
Addressee
' Bob Kievit-EPA
Kevin Rochlin-EPA
Feb. 12, 1988
Charles Findley- Henry Longest-
EPA EPA Headquarters
Dec. 30, 1987 34 Robie Russell-EPA
Nov. 4, 1987 5
Nov. 5, 1987 2
Nov. 4, 1987 94
May, 1988 6
Feb. 23, 1988 5
April 20, 1988 2
Feb. 9, 1988 3
Feb. 9, 1988 3
Lynn Bernstein-
Ecology
John Ostrowski-
Vancouver
Teresa Rider-
Foster Rider
& Associates
Ecology
Gregory Thomas-
ATSDR
David Rountry-
Ecology
David Rountry-
Ecology
David Rountry-
Ecology
Davi d .Rountry-
Ecology
Carol Fleskes-
Ecology
John Ostrowski-
Vancouver
Tom Barton-
Southwest WA
Health District
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FHC Institutional March 28, 1988 2
Controls
Institutional Controls Feb. 16, 1988 2
Ground Water Standards
and Requirements
Change in Agency Lead
at the Frontier Hard
Chrome NPL Site
Sixteenth Remedy
Delegation Report,
Part 1
Proposal Plan comment
letter
Proposal Plan comment
letter
Proposal Plan comment
letter
Feb. 12, 1988 3
March 16, 1988 1
March 3, 1988 5
June 10, 1988 1
June 6, 1988 1
May 24, 1988 2
John Ostrowski-
Vancouver
David Rountry-
Ecology
Carol Fleskes-
Ecology
Otto Neth/
Walter Neth
J. Winston
Porter-EPA
James Pomajevich
Eric Trued
Walter Neth
David Roontry-
Ecology
Dick Wailer-
Ecology
John Littler-
Ecology
Carol Fleskes-
Ecology
Reg. Administrators
Regions 1-X
Mike GalLagher-
Ecology
Mike Gallagher-
Ecology
Mike Gallagher-
Ecology
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RECORD OF DECISION
SUMMARY
SITE LOCATION AND DESCRIPTION
The Frontier Hard Chrome (FHC) site is located in the southwestern part of
the state of Washington, in the city of Vancouver, Washington. FHC is in an
industrial area of the city directly across the Columbia River from the city
of Portland, Oregon (see Figure 1). The area is generally flat, extending
south, east, and west. About one quarter mile to the north, a ridge rises
steeply to where a large residential area starts.
The site is approximately one-half mile north of the Columbia River and
covers about one-half acre. The area is within a floodplain that has been
extensively filled. There is a topographical depression about one and
one-half acres in size adjacent to the east end of the FHC site. The
depression is generally five to twenty feet below the level of the FHC site
and represents a remnant of the old floodplain that has not been filled in.
The groundwater table Is within twenty feet of the ground surface and is
affected by the stage height of the river. The groundwater is used as the
drinking water supply for the city of Vancouver, which has two well fields
within one mile of the site (see Figure 2, 3).
SITE HISTORY AND ENFORCEMENT ACTIVITIES
In approximately 1955, the site was filled with hydraulic dredge material
and construction rubble. Since then the site has been primarily occupied by
two businesses, both engaged in the chrome plating business. Pioneer Plating
operated at the site from 1958 to 1970. The site was then occupied by FHC
until 1983. The property has been leased to various other businesses since
1983. Presently the facility is being used as a storage and staging area for
a neighboring business.
During the operation of Pioneer and the initial operation of FHC, chromium
plating wastes were discharged to the sanitary sewer system. In 1975, the
city of Vancouver determined that the chromium in the wastewater from FHC was
upsetting the operation of its new secondary treatment system. FHC was
directed by the city and the Washington Department of Ecology (Ecology) to
cease discharge to the sewer system until a treatment system was installed to
remove chromium from their waste. At that time, FHC began discharge of their
untreated plating wastes to a dry well behind the facility.
In 1986, Ecology gave FHC a wastewater disposal permit for discharge to
the dry well in 1976 by Ecology. The permit also contained a schedule for the
installation of a treatment system for their wastes. Between 1976 and 1981,
several extensions of the permit and schedule were granted, as the deadlines
were passed without compliance.
In 1982, Ecology found FHC in violation of the Washington State Dangerous
Waste Act for the illegal disposal of hazardous wastes. Ecology also
discovered that an industrial supply well about one quarter mile southwesfof
FHC was contaminated with chromium at more than twice the drinking water
standard. FHC's wastewater permit was again modified with a new compliance
date. FHC again did not comply, with the permit requirements for economic
reasons, and in December 1982, the FHC site was proposed for inclusion on the
National Priorities List under CERCLA or Superfund. The listing was finalized
in September 1983.
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In 1983, Ecology ordered FHC to stop discharge of chromium plating wastes
to the dry well. FHC was also required to prepare a plan for the
investigation of the groundwater. • FHC closed down all operations at the
site. The company has not undertaken the investigation.
In March 1983, EPA and Ecology signed a Cooperative Agreement which gave
Ecology the lead in investigating the FHC site under Superfund. Ecology began
that investigation in the fall of 1984. The Remedial Investigation (RI) led
to a Feasibility Study to determine the cost-effective remedial action for the
FHC site. The Feasibility Study (FS) was completed in October 1987.
In December 1987, EPA published a ROD for the first operable unit at the
site, which addressed the soil contamination. Design work for this operable
unit began in April 1988, with the collection of soil samples from several
locations on site to be used for bench scale testing.
In March 198B, the lead agency for the site was changed from Ecology to
EPA in accordance with the revised operating agreement between the two
agencies.
The regulatory and enforcement actions at the FHC site have centered
around the owners of the site which was purchased and developed into a chrome
plating business in the mid-1950s. Under Superfund, they are responsible
parties and are liable for the cleanup of the site. Past negotiations between
the responsible parties, EPA, and Ecology have not been productive. Since
1976, FHC has not complied fully with any agency orders. The site owners have
not indicated any willingness or financial capability to undertake needed
remedial actions at the site.
COMMUNITY RELATIONS .
There.have been two public meetings for the purposes of informing the
local population about the activities at the site and providing opportunities
to comment. The initial meeting was held in October 1984 at the commencement
of the RI. The second meeting was held on November 4, 1987, to discuss the
RI, the FS, and the proposed alternatives.
This sit= has resulted in the contamination of the drinking water aquifjer
utilized in this community. The present drinking water supply is not now
affected. However, the potential industrial and commercial development of the
area will be. The public interest at this site has been limited.
Attendance at the meetings has been sparse. The meetings were attended by
the responsible parties and by people directly associated with the operation
of FHC. Adjacent property owners were also in attendance at the meetings. A
transcript of the November public meeting was made, and a responsiveness
summary was prepared. People who commented at the November 1987 meeting
indicated that there is no need to take any action at all at the FHC site,
with the exception of constructing an impermeable cap over the dry well area.
Media interest in the site has been limited. The local media was in
attendance at the November 1987 meeting. Much of the media interest centered
around the cost of the work which has been conducted to date and the future-
cost.
An additional public notice and comment period took place in May and June
1983, to present information and receive comment on the modified alternative
dealing with groundwater contamination (the subject of this ROD). An
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7
opportunity for a public hearing has given; however, no one from the public
requested one. Three comments were received on the proposed plan for
groundwater cleanup. One comment indicated support for the proposed plan, and
one indicated no objection to the plan. The third comment was from the site
owner, who indicated that the only remedial action needed is to construct a
building over the highly contaminated area and to blacktop over the remainder
of the site. Further information on these comments can be found in the
Responsiveness Summary.
Several meetings were held with local officials throughout the project for
the purposes of keeping them up to date on site activities and to receive
feedback from them. The city of Vancouver has indicated its support of the
action to be taken at the site.
GROUNDHATER CONTROL OPERABLE UNIT
EPA and Ecology have divided the work at the site into two different
phases called operable units. The second operable unit is the subject of this
ROD, which addresses contaminated groundwater. The first operable unit was
the subject of a ROD signed by EPA on December 30, 1987, which addressed
contaminated soils. That ROD calls for removing soils to a depth of 15 to 20
feet, mainly around the dry well on site, and chemically treating it to bind
chromium and other heavy metals to the soil. The treated soil will be
replaced, and the whole area will be covered with a relatively impermeable cap
to minimize the amount of precipitation entering the soil. Soil stabilization
is intended to prevent human contact with the contaminants, to prevent the
contaminants from leaking into the groundwater, from being carried to off-site
soils or to surface waters through rainfall or snowmelt events, and to prevent
the creation of air contamination from windblown dust. Additional details can
be found in the December 30, 1987, ROD.
The second operable unit will remove most of the chromium already in the
groundwater. The remaining chromium will be flushed slowly from the
groundwater through natural processes. The groundwater will be monitored, and
the use of groundwater will be controlled until the chromium levels meet
drinking water standards.
Together the work in both operable units will provide a wide range of _*
environmental protection by first eliminating the source of contamination,
which is in the soils, and then cleaning up contaminated groundwater.
SITE CHARACTERISTICS
This section will describe the results for the groundwater portion of the
RI conducted on the site. Soil contamination was addressed in a previous ROD
dated December 30, 1987.
The RI determined that there are three zones to the groundwater in the
area (see Figure 4). The upper, called the Level A zone, is a sand and gravel
layer beginning about 20 feet below the ground surface. It is about 10 to 15
feet thick and sits upon a confining layer of clay. The clay layer is
generally less than five feet in thickness and is not continuous throughout'
the area. Movement of groundwater in the Level A zone is approximately 0.5
feet per day to the south-southwest toward the Columbia River.
The next groundwater layer, called the Level B zone, is also made up of
sands and gravel but was found to be more permeable than the Level A zone.
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8
The Level 8 zone extends from ac :-ut 35 feet below the ground surface down -to
about 80 to 100 feet below the ground surface. The groundwater velocity in
this layer is about 2.25 feet per day to the south-southwest toward the
Columbia River. Hydraulic connection exists between the Level A and B zones,
but there are no distinct vertical gradients.
The lowest groundwater layer is called the Troutdale Formation which
begins about 100 feet below the ground surface in this area. The Troutdale is
interconnected with the Level B zone.
Aquifer pump tests performed in the Level A and B zones during the RI
indicate that the groundwater in the area can produce large quantities of
water with little drawdown.
The investigation found a plume of chromium-contaminated groundwater
extending from the site to the Columbia River about 1/2 mile to the south.
The contaminated plume is currently about 3000 feet long and 1500 feet wide.
The source of the plume is the highly contaminated soil around the on-site. dry
well. The dry well, which extends into the clay layer situated on the top of
the Level A groundwater zone, was used to dispose of untreated process
wastewaters until FHC closed in 1983.
The Level A zone was found to contain concentrations of chromium up to 300
parts per million (ppm), which is 6000 times the drinking water standard of
0.05 ppm (see Figure 5 for chromium concentrations in the Level A zone). The
highest concentration of chromium found in the Level B zone was 1 ppm (see
Figure 6 for chromium concentration in the Level B zone). Low and
inconsistent levels of lead and nickel were.found in the Level A zone ;;i the
area of the dry well. Most groundwater analyses did not detect any nickel or
lead and only two out of about 100 samples contained levels of lead above the
drinking water standard. These two metals are not believed to be a factor at
the site. Based upon the data available, the Troutdale Formation is not
believed to be impacted by the contamination. Since the Troutdale Formation
is interconnected with the Level B zone, the potential exists for the upper
portion of the Troutdale Formation to be affected in the future.
Although the chromium contamination in the groundwater has spread to the
Columbia River 1/2 mile away, most of it is located, in a highly concentrated '
plume in the vicinity of the dry well. About 65 to 70% of the total chromjum
in the groundwater is located in an oval-shaped plume within the Level A zone
that is about 300 feet long and 150 feet wide and contains total chromium
levels from 50 to 300 ppm. The chromium outside this hot spot diffuses
rapidly, although the levels 1/2 mile away are still above drinking water
standards.
The city of Vancouver has two municipal supply well fields drawing water
from groundwater zones interconnected with the contaminated zones. One well
field is about one mile to the east and contains six supply wells drawing
water from about 85 feet below the ground surface. The other well field is
about one mile to the north and contains five supply wells drawing water from
about 200 feet below the ground surface. There is also an irrigation supply
well about 1000 feet to the east, which draws water from about 105 feet below
ground surface. However, the investigation found that these wells were not
affected by the contamination from the FHC site. The RI also confirmed that
the wells were not in the direction of groundwater flow from the FHC site and
likely would not likely be contaminated in the future. The only wells
affected have been two industrial water supply wells used by FMC Corporation
about 1/4 mile southwest of the site. The wells, which draw water from 30 to
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95 feet, were found to contain 0.12 ppm chromium, which is about two times' the
drinking water standard. The" wells have not been used since 1983, when the
faci-1 i ty shut down.
The RI indicated that even with soil stabilization, groundwater will
remain contaminated for over 300 years if no groundwater remedial action is
taken. Groundwater in the area is a very important resource. Groundwater
and
:ies
an
increased need for groundwater.
___ — .___._ __ ___^_. _ _ ^
taken. Groundwater in the area is a very important resource. Groundwater
currently provides nearly all domestic water supplies and most industrial
municipal supplies, as the aquifers in the area can produce large quantiti
of water with little drawdown. Future growth in the area will result in a
The RI has also found that both the Level A and B zones at the site are
contaminated with organic solvents including tetrachloroethylene,
trichloroethylene and 1,1,1 trichloroethane. The solvents were found in
groundwater at concentrations generally less than 0.06 ppm, but also as high
as the following:
Drinking
Contaminant Level A zone Level B zone Hater Standards
Tetrachloroethylene 6.32 ppm 0.07 ppm —
Trichloroethylene 0.09 ppm 0.02 ppm 0.005 ppm
1,1,1 Trichloroethane 0.41 ppm 0.06 ppm 0.2 ppm
The RI did not determine the source or extent of this contamination, but the
highest levels were found In a monitoring well to the north of the dry well
(upgradlent) and In the Level A zone.
Th.e Columbia River itself was not sampled, but the groundwater discharge to the
river was modeled. The model showed that no measurable increase of chromium would
be detected in the river from the impact of the contaminated groundwater.
SUMMARY OF SITE RISKS
An endangerment assessment was conducted as part of the FS to evaluate the risk
to public health posed by the site and to assist in determining the proper level of
remedial response. The endangerment assessment examines the particular hazardous
substances at the site, the amounts of the substances which are found, the routes
of exposure or how people would encounter those substances, and the level s...of those
substances which are known to cause harm. The determination of this level of risk
provides an additional basis for the selection of remedial action.
Chromium is the hazardous substance of primary concern at the FHC site. It was
found in concentrations up to 300 ppm, which is 6000 times the drinking water
standard. Chromium is present in two forms, trivalent chromium and hexavalent
chromium. Of the two, hexavalent is the more hazardous. Most of the chromium
found in the groundwater on site is in the hexavalent form. Also, organic
solvents, primarily tetra and trichloroethylene and 1,1,1 trichloroethane, were
found in the groundwater at levels above health standards. Tetrachloroethylene is
classified as a probable human carcinogen and trichloroethylene is classified as a
potential human carcinogen. The chances of contracting cancer from drinking water
contaminated with the highest level of tetrachloroethylene found on site is
estimated at one in 100 over a lifetime of exposure. If no groundwater cleanup
action is taken, concentrations of chromium are expected to stay above the'drinking
water standard for about 300 years.
Nater supplies currently used in the area include two city of Vancouver
municipal supply wells about one mile to the north and one mile to the east of rhe
site and an irrigation well about 1000 feet to the east. These wells were sampled
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10
and found not to be affected by the site. Groundwater modeling done in the FS
indicates very little chance of the contamination spreading to these existing
wells, as they are not in line with the direction the contaminated plume is
spreading. However, any future well developed within or near the existing plume
contaminated groundwater would be severely impacted.
Observed : 'oundwater monitoring results for chromium show levels that present a
substantial and imminent endangerment to the public if drinking water resources
were developed in the area of the existing and predicted plume to the south of the
site. There is also concern over using groundwater from the highly contaminated
plume for irrigation or industrial purposes because of health effects from direct
human contact, accidental ingestion of contaminated soils, or indirect contact
through breathing contaminated water vapor.
Future water needs in the area are dependent on growth of the Vancouver area.
Although it is impossible to forecast growth over a 300 year period, it is very
probable that Vancouver and its environs will grow over this period. Future growth
in the Vancouver area will result in increased water demand for industrial,
commercial, agricultural, and domestic purposes. Groundwater currently provides
nearly all domestic water supplies, most industrial and municipal supplies, and
more than half the irrigation supplies in Clark County. Groundwater supplies near
the Columbia River are particularly Important, as large volumes of water are
available at relatively shallow depths. The groundwater aquifer 1n the area of the
site is very productive as evidenced by pump tests conducted during the RI and by
the two municipal well fields within one mile of the site. To leave a large area
of this aquifer contaminated with levels of chromium above health standards for 300
years represents an unacceptable future risk to public health.
As the contaminated plume of groundwater ultimately flows to the Columbia
River, the possible impact on aquatic life in the river was investigated in the
FS. The concentrations of chromium in the groundwater immediately adjacent to the
Columbia River were predicted using a groundwater flow simulation model. With no
groundwater cleanup, the level of chromium at receptors along the river was
predicted to rarely exceed the chronic aquatic toxicity standards for hexavalent
chromium at 0.011 ppm. This is due to dilution of the contaminated plume which
occurs as groundwater migrates to and enters the river.
DESCRIPTION OF ALTERNATIVES .
The alternatives evaluated for this ROD specifically address the hazards
associated with contaminated groundwater at the site. A ROD evaluating
alternatives addressing soils and building contamination was issued on December 30,
1987.
The basic remedial alternatives developed and evaluated in the FS are:
1. No action - groundwater contamination will be monitored only.
2. Extraction and treatment of all contaminated groundwater until the aquifer
meets drinking water standards. This alternative would involve
construction of a series of groundwater extraction wells (approximately 21
wells) and construction of a treatment plant to remove the contaminants
from the extracted groundwater. The system would extract and trea-t about
18 million gallons & day for about 15 years. A pipeline and pumping ^
system would be constructed to transport and dispose of treated water intM
the Columbia River. The extracted groundwater would be treated to a level
that is protective of aquatic life in the Columbia River (.011 mg/1
hexavalent chromium).
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11
3. Extraction and treatment of contaminated groundwater in the Level A zone
only until the upper portion of the aquifer meets drinking water
standards. This alternative was developed because the Level A zone is
much more contaminated than the Level B zone, the volume of water to be
treated is much less than in the Level B zone, and the water in the Level
A zone is closer to the ground surface than is the Level B and thus more
accessible to the public. This alternative involves construction of a
series of groundwater extraction wells (approximately 15 wells) and
construction of a treatment plant to remove the contaminants from the
extracted groundwater. This system would extract and treat about 1.1
million gallons a day for about 15 years. A pipeline and pumping system
would be constructed to transport and dispose of treated water to the
Columbia River. The extracted groundwater will be treated to a level
protective of aquatic life in the river (.011 mg/1 hexavalent chromium).
EPA and Ecology developed an additional alternative subsequent to the
completion of the FS. This alternative was evaluated along with the previous three
mentioned. This alternative includes the following:
4. Extraction and treatment of the highly contaminated plume of groundwater
(or hot spot) around the dry well. Levels of total chromium in this hot
spot contain from 50 to 300 ppm or more of chromium and represent
approximately 65 to 70 percent of the total chromium contamination in the
aquifer. This area is about 300 feet long and 150 feet wide and extends
out from the dry well in a southerly direction. Treatment of this hot
spot will continue until chromium concentrations are reduced to 10 ppm.
This is the concentration at which groundwater chromium concentrations are
expected to equilibrate after pumping groundwater from extraction wells
within"the zone of high contamination levels.
This alternative involves construction of a system of wells to extract
contaminated groundwater from within the hot spot (about 7 wells) and a
treatment plant to remove contamination c-:-m the extracted groundwater.
The system would extract and treat appro nately 300,000 gallons a day for
a period of 2 to 5 years. The treated groundwater would then be
discharged either to the'City of Vancouver sanitary sewer where it would
be processed through a secondary sewage treatment plant and then
discharged to the Columbia River or directly to the Columbia River through
. a pipeline and pumping system. The extracted water will be treated to a
level that is protective of aquatic life in the Columbia River or to a
level that meets the City of Vancouver's pretreatment requirements
depending on the location of discharge. If it is pumped directly to the
river, a half-mile pipeline, and pumping system would be constructed from
the site to the River. Very little pipeline construction would be needed
if the treated water were discharged to the Vancouver sewage system as the
site is already served by the sewer system.
The alternative also consists of implementing institutional controls that
will prevent anyone from drilling wells into or near the area of the
contaminated plume of groundwater without the approval of EPA or Ecology
until chromium levels reach drinking water standards. This groundwater
control area is shown on Figure 1.
Various wastewater treatment technologies were considered and evaluated "against
agency criteria. The treatment technologies considered for the removal of chromium
from groundwater follow:
1. Ion e
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12
3. Carbon adsorption
4. Precipitation and sedimentation
5. Reverse osmosi s
6. Filtration
7. Distillation
The treatment technologies considered for removal of solvents from groundwater were
1. Carbon adsorption
2. Air or steam stripping
3. Ozonation
4. Distillation
Selective media ion exchange for chromium removal and carbon adsorption for
solvent removal were chosen as being able to best meet agency criteria for the
groundwater treatment alternatives considered for this site. A detailed review and
evaluation of these treatment technologies are presented in the FS.
Various options for disposal of treated groundwater were also considered and
evaluated against agency criteria. These options include:.
1. Discharge into the city of Vancouver's sanitary sewer
2. Construction of and discharge to a pumping system and pipeline to the
Columbia River
3. Reinject into the aquifer
Reinjection into the aquifer was eliminated because of technical difficulties
in injecting the treated water back into the aquifer and because of the potential
to unintentionally spread the zone of contamination. The city of Vancouver and
Ecology have indicated their opposition to reinjection of the treated water into
the aquifer.
Discharge into the city of Vancouver sewer system was eliminated.for basic
alternatives two and three, because the sewer system could not handle their large
flows. Discharge into the Vancouver sewer system is a viable option for
alternative four.
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
Four basic alternatives were compared and evaluated according to the following
criteria:
1. Overall protection of human health and the environment;
2. Cost;
3. Compliance with applicable or relevant and appropriate requirements;
4. Long-term effectiveness and permanence;
5. Short-term effectiveness;
6. Reduction of toxicity, mobility, or volume of hazardous substances;
7. Implementabi1ity;
8. State acceptance; and
9. Community acceptance
Table 1 on pages 14 and 15 compares the strengths and weaknesses of eacti
alternative with respect to the nine criteria.
As indicated in Table 1, state and local government officials expressed the
opinion that the alternatives which cleaned up the aquifer in the shortest
ti'tieframes (alternatives #2 and #3) are not worth the additional expense. For"
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13
Fund-financed remedial actions, CERCLA/SARA requires the state to pay ten percent
of the costs. Additionally, the law requires EPA to consider public and state
comments. Thus, comments received from the public and state and local officials
and the state's unwillingness to fund more costly remedies weighed heavily in EPA's
decision-making process.
After evaluating the four alternatives according to the above nine criteria,
EPA has determined that alternative number four, treatment of the hot spot,
represents the best balance among the evaluation criteria.
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14
Summary of Remedial Alternatives
Alternative
Description
Cost
(present worth)
Protection of
Public Health
and the
Envi ronment
ARARs
No Action
No further action
monitoring only.
$238,000
Leaves a large
area of a
productive aquifer
contaminated with
chromium levels
above health
standards for
about 300 years.
No attempt to meet
regulations.
Treat Level A & B
Treats Level A & B
groundwater zones to
drinking water standards
Essentially removes all
chromium In groundwater.
about $93 million
Restores the aquifer to
drinking water standards
In about 15 years.
Meets ARARs In 15 years.
Treat Level A
Treats only the Level A
groundwater zone to
drinking water standards
$13 million
Restores the upper
zone of the aquifer to
drinking water standards
in about 15 years and
restores the lower zone
in about 40 years.
Meets ARARs in 15 years
for Level A zone and 40
years for Level B zone.
Treat Hot Spot
Treats only the
highly contaminated
hot spot around the
dry wel1 (chromium
levels above 50 ppm)
$3.8 million
Removes most of the
chromium in
groundwater by
treating the hot
spot. Restores
lower zone to
drinking water
standards in 40 years
and upper zone in 100
years.
(Meets ARARs in 40
years for Level B
zone and 100 years for
Level A zone.
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15
A) ternative
Short-term
effecti veness
Long-term
effectiveness
and performance
Reduction of
toxici ty,
mobility, and
persistence
No Action
Not effective.
Does nothing.
Large section of
aquifer not
usable for next
300 years.
Al1 chromium In
groundwater
slowly discharges
to the river over
U;e next 300 years,
Does
this
nothing
regard.
In
Treat Level A & B
Restores the entire aquifer
to drinking water standards
In shortest time possible -
15 years.
Best alternative - entire
aquifer restored In 15
years. Reduces chrome load.
Reduces chromium load to
Columbia River by almost
100%.
Removes essentially all
contaminants within 15
years.
All treatment options
may recycle the chromium
Into a useful product.
The removed solvents will
be handled according to
RCRA requirements.
Treat Level A
Restores upper portion of
aquifer to drinking water
standards in shortest
time possible - 15 years.
Lower portion of aquifer
will not be restored for
about 40 years.
Second best alternative -
upper portion of aquifer
restored in 15 years.
Reduces chromium load to
Columbia River by almost
80%.
Removes essentially all
contaminants from the
Level A zone within
15 years.
Treat Hot Spot
Removes most of the
chromium in the
groundwater:
eliminates the highly
contaminated hot spot
in 2 to 5 years.
Lower aquifer wi11 not
be restored for 40
years and upper
aquifer for 100 years.
Upper portion of
aquifer meets drinking
water standard in 100
years and lower aquifer
meet standards in 40
years. Reduces
chromium load to the
Columbia River by
65-70%.
Removes about 70% of
the contaminants in
the Level A zone
within 2 to 5 years.
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16
Alterna^
Technical
feasibi1i ty
and implement-
abi1i ty
State
acceptance
Communi ty
acceptance
No Action
The state has
recommended
that treatment
of the hot
spot be done.
Comments 'at the
public hearing In
November 1987
indicate that no
action is needed.
Treat Level A & B
All actions Involve the
same technology which
Is proven and easi1y
Implemented.
The state has Indicated that
these two treatment options
are too costly to Implement.
Other than the site owners,
former operators, a few
neighboring businesses, and
officials from the city of
Vancouver and Clark County,
only two comments were
received from the community.
The site owners and former
operators have Indicated no
action Is needed. The city
of Vancouver and Clark County
have Indicated that cleanup
of the hot spot should be
done. One comment from the
community Indicated support
of the proposed alternative,
and one Indicated no
objections to the proposed
alternative.
Treat Level A
Treat Hot Spot
The state has
recommended this
alternative to EPA,
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17
THE SELECTED REMEDY
The selected remedy will use a series of groundwater extraction wells to
pump groundwater from the most contaminated area of the Level A zone, the area
around the dry well. This area is about 300 feet by 150 feet and contains
chromium levels above 50 ppm (see Figure 7). The water will be treated using
selective media ion exchange to remove the chromium. As the water passes
through a column of resin beads, the chromium chemically beads and is removed
from the water. This process yields a stream of treated water and a waste
stream of chromium and spent resin. The chromium is then removed from the
resin and and may be recycled for use in the chrome plating industry. The
process is called selective media ion exchange because chromium is selectively
removed from the water. Ion exchange is often used for metal removal and is a
proven, highly effective technology. Selective media ion exchange is a more
sophisticated form of this technology.
The water will be further treated using carbon adsorption to remove the
organic solvents that were found in the groundwater. Carbon adsorption refers
to a treatment process that uses carbon particles to absorb contaminants from
a liquid. Adsorption is a natural process in which molecules.of a gas or
liquid are attracted to and are held at the surface of a solid. The organics
concentration will be reduced to a level that 1s protective of aquatic life in
the Columbia River or to a level that Is specified by the city of Vancouver's
sanitary sewer pretreatment program, depending on the discharge location. The
details of this treatment process will be further defined when the source and
extent of the organic solvent contamination is identified in the Remedial
Design phase of the project.
The extracted groundwater will be treated to a level that would protect
aquatic life in the Columbia River (0.011 mg/1 hexavalent chromium) or to a
level acceptable for discharge to the Vancouver sanitary sewer system,
depending on which is cost effective. The specific method of treated water
disposal will be determined during design. A direct discharge to the Columbia
River will necessitate construction of a pipeline and pumping system from the
site to the Columbia about 1/2 mile away. Discharge to the Vancouver sanitary
sewer system will require a much shorter pipeline, as the site is served by
the sanitary sewer system. The treatment system will operate until the
concentration of chromium in the extracted -groundwater falls below 10 mg/1
after the extraction pumps are shut down for a period, allowing the
groundwater system to stabilize. This is estimated to take from two to five
years. After the treatment is completed, natural flushing action of the
aquifer will slowly remove the remaining chromium contamination, and the
groundwater will be monitored until chromium concentrations meet drinking
water standards. This is estimated to take about 40 years for the Level B
groundwater zone and about 100 years for the Level A groundwater zone.
EPA, Ecology, the city of Vancouver, and Clark County will jointly develop
institutional controls that will restrict the use of groundwater in and around
the contaminated plume of groundwater. The area where groundwater use will be
restricted is shown in Figure 1 and is described as the area south of
Fifth Street to the Columbia River, bounded by Reserve Avenue to the west and
Grove Avenue to the east. These corvrols will be designed to last until
chromium levels reach drinking water standards.
As discussed in the "Summary of Site Risks," the main risk at the site is
development of new wells in and around the contaminated plume of groundwater.
It is likely that there will be increased need for groundwater from chis area
sometime in the future. Although the selected remedy will not clean up
groundwater as quickly as the more costly alternatives, it will eliminate the
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18
highly contaminated hot spot within a few years, thereby lessening the risk to
anyone exposed to the contaminated groundwater despite the institutional
controls that will be put into effect. The selected remedy will also
substantially reduce the time required to cleanse the aquifer to drinking
water standards, thereby lessening the dependency on long-term institutional
controls to protect public health.
STATUTORY DETERMINATIONS
The selected remedy will provide adequate protection for human health and
the environment through the combination of treatment and institutional
controls. The remedy will remove an estimated 65 to 70 percent of the
chromium in groundwater by cleaning up the area of highest contamination.
Institutional controls will prevent use of the contaminated groundwater until
contaminant levels reach drinking water standards. The groundwater extraction
and treatment system will not pose any unacceptable short-term risks.
Contaminants removed from the groundwater will not be transferred to any other
media, such as surface water or the air.
The selected remedy will attain all Applicable or Relevant and Appropriate
Requirements (ARARs) of the federal and state environmental and public health
laws and regulations. The laws and regulations of concern include the
following:
Safe Drinking Water Act (SDWA) (42 U.S.C. 300); Primary Drinking
Water Standards (40 CFR 141).
The selected remedy prevents exposing the public to drinking water which
exceeds the Maximum Contaminant Levels. These levels are 0.05 mg/1 for
hexavalent chromium; 0.005 mg/1 for trichloroethylene; and 0.2 mg/1 for 1,1,1
trichloroethane.
[This requirement is relevant and appropriate.]
Clean Water Act (33 U.S.C. 1251); National Pollution Discharge
Elimination System (40 CFR 122), NPDES Permit Program (WAC 173-220),
State Waste Discharge Permit Program (WAC 173-216).
The sel-ected remedy treats the extracted water before discharge to the
Columbia River or to the Vancouver sanitary sewer system and will meet all
substantive requirements of the NPDES program. If treated water is discharged
to the Columbia, it will meet EPA Water Quality Criteria for the protection of
freshwater aquatic life. If it is discharged to the. Vancouver sanitary sewer
system, the treated water will meet or exceed the city's pretreatment
requi rements.
[This requirement is applicable.]
State of Washington Water Well Construction Act (RCRW 18.104);
Minimum Standards for Construction and Maintenance of Water Wells
(WAC 173-160).
The requirements govern the design of extraction and monitoring wells.
[This requirement is applicable.]
Resource Conservation and Recovery Act (RCRA) (42 U.S.C. 6901); RCRA
regulations (40 CFR 261 to 280); Washington State Dangerous Waste
regulations (WAC 173-303) .
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19
The spent activated carbon used in the treatment process will be handled
in accordance with all substantive requirements of the above.
[This requirement i-s relevant and appropriate.]
The selected remedy affords overall effectiveness in protecting human
health and the environment proportional to its cost. The remedy will remove
an estimated 65 to 70 percent of the chromium in the groundwater and prevent
use of the contaminated groundwater until safe levels are reached through
natural flushing. The selected remedy has an estimated present worth cost of
$3.8 million, compared to $13 million for the alternative that reduces the
chromium concentrations to -drinking water standards throughout the Level A
zone, and $93 million for the alternative that reduces chromium concentrations
to drinking water standards in both the Level A and B zones. The alternatives
that reduce chromium concentrations to drinking water standards within either
the Level A or Level A and B zones will shorten the estimated time until the
groundwater meets drinking water standards; however, in light of public and
state and local government comments and the need for the state to provide a
ten percent cost share for the remedi?.! action, EPA has determined that these
remedies do not represent the best balance among the CERCLA/SARA cleanup
criteria. The alternative that consists of no groundwater treatment
represents unacceptable future public risks, does not meet CERCLA/SARA
requirements, and thus Its costs cannot be compared to these other
alternatives.
The selected remedy utilizes permanent solutions and alternative treatment
or resource recovery technologies to the maximum extent practicable. The
remedy removes an estimated 65 to 70 percent of the chromium in the
groundwater and recycles it into chromic acid which can then be used in the
plating industry. Although some chromium contamination will remain in the
groundwater, it is determined that the cost and amount of time needed to
extract the remaining chromium are not necessary to adequately protect public
health and the environment and meet CERCLA/SARA cleanup criteria. During the
two public comment periods, no one expressed a view that more chromium should
be removed from the groundwater. However, the city of Vancouver indicated
that the chromium hot spot in the groundwater should be cleaned up. The state
of Washington and the city of Vancouver indicated that they could not support
an alternative that removed all chromium from either the Level A or Level A
and B zones because of the high cost.
The selected remedy satisfies the statutory preference for remedies
employing treatment that permanently and significantly reduces toxicity,
mobility, or volume of hazardous substances.
Because this remedy will result in hazardous substances remaining on-site
above health-based levels, a review will be conducted within five years after
commencement of remedial actitm -to ensure that the remedy continues to provide
adequate protection for human health and the environment. This review will
include a look at the contaminated plume of groundwater through a groundwater
monitoring network to ascertain whether the plume is moving as predicted. It
will also include a review of land use around the site, changes in need for
water from the aquifer and the effectiveness of institutional controls used to
prohibit use of contaminated groundwaters. If the review shows the need for
additional action to protect human health or the environment, the ROD will be
revised as necessary.
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^- WASHINGTON ' ;:j:;-'"
""—'OREGON ~"~rj
l
COL? CLUB <
Approx. Scale: ^''- 2000'
Vicinity Map
Location Map
Frontier Hard Chrome
Darrves & Moore
-------
Vancouver
*/ Well Sl»lion * I
E. Mill Plain Olvd
E. Evergreen Blvd.
PROJECT SHE
LOCATION
O •
Washington School
lor the Deaf Well
Pearson Alrporl
Vancouver
Well Station H 4
0 1000 Feet
Frontier Hard Chrome Site Location
-------
Angola! Molals
Cox Cable
Dltcherge Line* to Sump
•nd Dry Well (1976-1083)
Frontier
Hard ChronM
Rlchvdion
Malal Work!
C«e»ldy I
I— Mlo. ,-J
^Olacharge Line
(1976-7)
Suipected Chromic Acid
Dltcharg* Line (Dales Unknown)
ISO
Seal* In F«rl
Known/Suspected Wastewater
Discharge Points
Frontier Hard Chrome
Dames & Moore
Job No 7927-OOJ
Figure 1-2
-------
Level A Monitoring Well
Level B Monitoring Well
0 1
5 -
10 -
15'-
o
a
«j
r 20
. 3
CO
•a
c
o 25
t_
O
2
t- 40 -
45 -
50 -
55 -I
.Ground Surface
VAOOSE ZONE: Fill
.Aquifer Water Level
Localized Perched
Ground Water
Low Permeabilty Lens: SHty Sandy Gravel
UPPER ZONE
ALLUVIAL AQUIFER
LQWER AQUITARD
Moderate to High Permeability: Sandy Gravels
•Localized
f Aquitards
LOWER ZONE
ALLUVIAL AQUIFER
-------
V i
v --7 /
/./
* g*»-r*
"7
/-...,.. . /
ysy. /
f f I
A7 '
\ ' A
\
/ST..
WBS-3B Wall Designation
/r{. 0-19 ' Total Chromium Concentration (ppm)
0.071/0.062 Duplicate Sample
0.5 Inferred Concentration Contour (ppm)
NO Not Detected
< 0.005 Below Detection Limit
Inorganic Water Analysis
Level A Monitoring Wells Total Chromium
Frontier Hard Chrome
• Dames & Moore
Pi
-------
yjol......
c-y
/ o., ... / -..-•«
/
*r
/
V— /^
WSS-3B we» Designation
-^•°'19 Total Chromium Concentration (ppm)
0.071/0.062 Duplicate Sample
°'S Inferred Concentration Contour (ppm)
NO Not Detected
< 0.005 Below Detection Limit
Inorganic Water Analysi
Level B Monitoring Wells Total Chromiur
Frontier Hard Chn
Dames &
Pi
-------
0 1JlKsents approximate location of groundwater
"^ wells
XjjX
01
1-1
3
W
•r-1
u.
150
Sctto In Foot
-------
Frontier Hard Chrome Site
Responsiveness Summary
Overview
This responsiveness summary discusses issues raised by the public
regarding contaminated groundwater at the site. The selected remedy is to
pump and treat groundwater from the area of greatest chromium contamination
and to prevent anyone from using contaminated groundwater until concentrations
are reduced to drinking water standards. A Record of Decision (ROD),
including a responsiveness summary addressing contaminated soils, was issued
on December 30, 1987.
A review of both responsiveness summaries will give a more complete
picture of public sentiment concerning the site. The majority of public
comments indicate a belief that no groundwater cleanup is necessary. Comments
received from local officials indicate that they support a partial groundwater
cleanup.
Background on Community Involvement and Concern
The public interest at the site has been limited. There have been two
public.meetings about the site. One was held In October 1984, at the start of
the Remedial Investigation (RI), and one was held in November 1987, at the
completion of the Remedial Investigation/Feasibility Study (RI/FS). The
meetings were attended mostly by the site owners, former operators of Frontier
Hard Chrome (FHC), and adjacent property owners.
The site owners and former operators have expressed the view that no
groundwater cleanup is needed, since no one is currently using water from the
contaminated plume. The adjacent property owners were concerned about the
effects of the contamination on their businesses and about whether the
proposed cleanup actions will interfere with their businesses.
Meetings with local officials have taken place periodically. The last two
meetings held were in November 1987 and April 1988. Local officials have
expressed their displeasure over the length of time the investigations have
taken, but have generally expressed support for the proposed plans.
The following public concerns have been raised:
Question: What will be the disposition of the FHC property?
Agency Response: The on-site soil stabilization project will take
approximately two years to complete, and the groundwater pump and treat
proj.ect will take from two to five years to complete. Site activity will be
restricted to cleanup activities during this period. After the cleanup is
completed, land use will be restricted to those activities that will not
disturb the stabilized soils. Some examples of activities that may disturb
the stabilized soils are heavy loadings or underground structures. The
restrictions will be developed during the design phase of the project.
Additionally, monitoring wells on the site will have to be maintained until
groundwater meets drinking water standards, which is estimated to take
approximately 100 years. The monitoring wells will not cause a significant
restriction in the use of the site.
-------
Question: What will be done to ensure that no one is exposed to the
contamination left on site when the cleanup is concluded?
Agency Response: The stabilized soil will be covered with a relatively
impermeable cap to prohibit human contact with the soils. Future site
activities will be limited to those activities that will not disturb the
stabi1ized soiIs.
Institutional controls will prohibit anyone from constructing a
groundwater well in or near the contaminated plume. The main control will be
the city of Vancouver plumbing code, which requires any new construction to
have the approval of the local health department for the building's water
system. The health department will not approve a building for occupancy if it
plans to obtain groundwater from the zone in or near the contaminated plume.
This zone is described as the area'south of Fifth Street to the
Columbia River, bounded by Reserve Avenue to the west and Grove Avenue to the
east. Additionally, the U.S. Environmental Protection Agency (EPA) will
conduct a review every five years after cleanup has been completed to ensure
that the remedy continues to provide adequate protection for human health and
the environment.
Question: What effects will the contamination have on the Columbia River
before, during, and after cleanup?
Agency Response: Modeling done during the RI Indicates that there will be no
measurable increase of chromium in the Columbia River either before or after
the cleanup. If treated wastewater is discharsed directly to the Columbia
River during the cleanup, this water will meet standards designed to protect
freshwater aquatic life.
In summary, the contamination is not expected to have a measurable impact
on the Columbia River.
Question: What about adjacent properties? Will they be safe to use?
Agency Response: As long as the owners of adjacent properties do not attempt
to extract and use groundwater from their properties, they should be safe to
use. There may be temporary impacts on one or two adjacent businesses during
the soil stabilization project or during the construction of groundwater
extraction wells, but the possibility or extent of those impacts are not yet
known and will be investigated during the design phase of the project.
EPA will try to avoid or at least limit any impacts on adjacent
properties. There may be a need to place groundwater monitoring wells on
adjacent properties, but the impact of a monitoring well should be very
1imi ted.
Question: Are there any other health concerns citizens should be aware of?
Agency Response: The main concern at the FHC site is the possible contact
with or use of contaminated groundwater. Even with the cleanup of the hot-
spot centered around the dry well, groundwater will remain contaminated with
chromium above drinking water standards for about 100 years in the upper zone
and about 40 years in the lower zone. The groundwater will not be safe to use
for that period of time.
-------
Summary of Public Comments and Agency Responses
A public notice and comment period took, place in May and June of 1988 to
present information and to receive comments on the proposed plan for
groundwater cleanup. An opportunity for a public meeting was given; however,
no one from the public requested one. During this time, three written
comments were received on the proposed plan for groundwater cleanup. One
comment indicated support for the proposed plan. The second comment, from the
owner of property located above the contaminated plume about 1/4 mile from the
FHC site, indicated no objection to the proposed plan. The owner of the FHC
site indicated that the only action needed is to construct a building over the
heavily contaminated area and to blacktop the remainder of the site. He also
indicated that the dry well could possibly be backflushed and the contaminated
water discharged directly to the Columbia River through a storm sewer.
Agency Response: Construction of a building and placing b-lacktop over the
contaminated area would place a barrier between the public and the
contaminated soils. However, the highly contaminated soils around the dry
well would continue to release chromium to the groundwater and cause further
contamination of the aquifer. This groundwater would remain contaminated and
would be unsuitable for drinking, irrigation and other domestic uses for
hundreds of years. Groundwater In this area Is an extremely important
resource.
Groundwater currently provides nearly all domestic water supplies, most
Industrial and municipal supplies, and more than half the irrigation supplies
in Clark'County. Groundwater supplies near the Columbia River are
particularly important, as large volumes of water are available at relatively
shallow depths. Although there are no existing wells being used in the
contaminated plume, future growth in the Vancouver area will create the need
to develop additional groundwater resources. Although the amount of growth
over the next few hundred years is impossible to predict, it is reasonable to
assume that Vancouver will grow and additional groundwater resources ^ill be
needed.
The selected remedy was chosen to limit the spread of contamination,
remove the majority of the contamination while most of it is still
concentrated in a hot spot around the dry well, and reduce the time it will
take the aquifer to naturally cleanse itself.
The groundwater in the area of the dry well is highly contaminated and
contains chromium that is almost 30,000 times the water quality standard for
the protection of freshwater aquatic life. This contaminated water could
cause significant harm to aquatic life if discharged directly to the Columbia
River. According to federal and state law, dilution of contaminated water
cannot be used as a substitute for treatment. Even if dilution was allowed to
substitute for treatment, it would take 30,000 gallons of clean water to
dilute one gallon of contaminated water down to a level that would be
protective of aquatic life in the river. Any contaminated groundwater that is
extracted must be treated before disposing it.
Additionally, there are no storm sewers available to discharge to in the
area. The city of Vancouver had preliminarily planned to construct storm
sewers and dispose of the collected water in dry wells in the area. However,
the contamination of groundwater in the area has prohibited the construction
of dry wells, as the dry-wells would create the opportunity to exacerbate•the
existing contamination problem by spreading the chromium-contaminated plume
even further.
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