United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R05-91/153
December 1990
Superfund
Record of Decision:
Oak Grove Sanitary Landfill,
MN
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50272-101
REPORT DOCUMENTATION i. REPORT MO. 2.
PAGE EPA/ROD/R05-91/153
4. Tide and Subtitle
SUPERFUND RECORD OF DECISION
Oak Grove Sanitary Landfill, MN
Second Remedial Action - Final
7. AuthOf(i)
9. Performing Organization Nam* and Addreu
12. Sponaoring Organization Nairn and Addreu
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
3. Recipient1 • Accmalon No.
5. Report Date
12/21/90
6.
8. Performing Organization Rept No.
10. Project/Taak/Work Unit No.
11. ContracqC) or Grarrt(G) No.
(C)
(G)
13. Type of Report & Period Covered
800/000
14.
15. Supplementary No tot
18. Abstract (Limit: 200 word*)
The 45-acre Oak Grove Sanitary Landfill is a former municipal and industrial solid
waste landfill in Oak Grove Township, Anoka County, Minnesota. Land consists of low
regions of uplands and sand dunes interspersed among numerous lakes and wetlands. The
nearby developed land use in the area is agricultural and residential. The site
overlies two aquifers, which are separated by a semi-confining layer. The deeper
aquifer provides regional potable water and supplies many area residential wells.
Landfill operations began in 1967 and continued until 1984, when the operating license
was suspended. An estimated 2.5 million cubic yards of waste is present in the
landfill including acidic oil sludge, paint and solvent waste, foundry sands and
sludge, inorganic acids, metal sludge, and chlorinated and unchlorinated organic
compounds from pesticide manufacturing. In addition, lime sludge was used as a cover
material on two thirds of the landfill. A 1988 Record of Decision (ROD) addressed the
sources of contamination by containing the onsite waste and contaminated soil with a
cover. EPA investigations in 1989 determined that the contaminated shallow aquifer
discharges directly to the surface water of the adjoining wetlands where ground water
contamination is being reduced by natural attenuation, and thus, limiting migration of
(See Attached Page)
MN
17. Document Analyaia a, Deacriplor*
Record of Decision - Oak Grove Sanitary Landfill,
Second Remedial Action - Final
Contaminated Medium: gw
Key Contaminants: VOCs (benzene, toluene, xylenes) and metals (arsenic)
b. Identiflera'Open-Ended Terma
c. COSATI Reid/Group
Availability Statement
18. Security Claaa (This Report)
None
20. Security Clau (Thia Page)
None
21. No. of Pages
64
22. Price
(See ANSI-Z39.18)
See Instructions on Revert*
OPT1OHAU TOHS1272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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EPA/ROD/R05-91/153
Oak Grove Sanitary Landfill, MN
Second Remedial Action - Final
stract (Continued)
contaminants to the surface water. This ROD addresses remediation of contaminated
shallow ground water, prevention of significant impacts on surface water from the
discharge of contaminated shallow ground water, and provides for continued use of the
deep aquifer as a drinking water supply. The primary contaminants of concern affecting
the ground water are VOCs including benzene, toluene, and xylenes; and metals including
arsenic.
The selected remedial action for this site includes long term monitoring of the shallow
and deep aquifers, surface water, and sediment at a frequency of three times per year for
the first year and semi-annually thereafter; natural attenuation of shallow ground water;
abandoning non-essential wells; and implementing institutional controls including ground
water use restrictions. The estimated present worth cost for this remedial action is
$800,000, which includes an annual O&M cost of $90,000 for the first year and $70,000 for
subsequent years.
PERFORMANCE STANDARDS OR GOALS: Sediment, ground water, and surface water monitoring
will assure that contaminant levels do not exceed SDWA MCLs, CWA AWQCs, and State surface
water quality standards.
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OAK GROVE SANITARY LANEFILL
DECLARATION FCR THE RECCED OF DECISION
SITE NAME AND LOCATION
Oak Grove Sanitary Landfill,
Oak Grove Township, Anoka County, Minnesota.
OF BASIS AND PURPOSE
This decision document represents the selected ground water
operable unit remedial action for the Oak Grove Sanitary Landfill
Site developed in accordance with the Conprehensive 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, consistent with the
National Oil and Hazardous Substances Pollution Contingency Plan
(40 CFR Part 300) . This decision is also in accordance with the
Minnesota Environmental Response and Liability Act of 1983.
The decision is based upon the contents of the administrative
record for the Oak Grove Sanitary Landfill site.
The State of Minnesota and the United States Environmental
Protection Agency (U.S. EPA) agree on the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action
selected in this Record of Decision (ROD) , may present a current
or potential threat to public health, welfare, or the
environment.
DESCRIPTION OF THE
This operable unit is the second of two operable units for the
site. The first operable unit addresses the source of
contamination by containing the on-site wastes and contaminated
soil with a cover. This p'-irticular cover system was documented
in a September 1988, ROD. The operable unit described in this
decision document addresses ground water contamination.
The remedy selected for ground water contamination includes
continued monitoring of both aquifers present at the site as well
as monitoring of surface water and sediments. The selected
remedy also incorporates institutional controls on the placement
of drinking water wells and natural attenuation of shallow
contaminated ground water. This remedy when used .in conjunction
with the final cover system, addresses the threat posed by
contaminated ground water by eliminating or reducing the risks
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posed by the site, through engineering controls.
The major corponents of the selected remedy include:
Long tern monitoring of the shallow and deep aquifers for
volatile organic conpounds, arsenic, barium, nickel, zinc,
pesticides, PCBs and nutrient parameters.- A minimum of
twelve wells will be monitored.
Long tern monitoring of surface waters for the same
constituents which are monitored for in ground water.
Surface water monitoring points will be established based
en a conductivity survey.
Long term monitoring of sediments for arsenic, barium and
nickel. Sediment sanple points will be located where
surface water sampling occurs.
Sediments, ground and surface waters will be sampled at a
frequency of three times per year for the first year and
semi -annually thereafter.
Institutional controls will be implemented and non-
essential wells would be abandoned.
Natural attenuation of shallow ground water.
This action will require operation and maintenance activities to
ensure continued effectiveness of the remedial alternative. The
action being taken is consistent with Section 121 of CERCLA as
amended by SARA, 42 U.S.C. Section 9621.
STATUTORY
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action and is cost-effective. This remedy utilizes
permanent solutions and considers alternative treatment (or
resource recovery) technologies to the maximum extent practicable
for this site.
The results of the Remedial Investigation and Feasibility Study
indicate that the toxicity, mobility and volume of contaminants
in the ground water are being addressed via natural attenuation.
Thus, treatment of ground water to permanently and significantly
reduce the toxicity, mobility and volume of contaminants was not
found to be necessary to protect human health and the
environment, or to be practical at the site at this time.
Because this remedy will result in hazardous substances remaining
on-site above health-based levels, a review will be conducted
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within five years after uoiiuiencement of remedial action to
ensure that the remedy cxartinues to provide adequate protection
of human health and the environment. If, however, the analytical
results generated as a result of monitoring' ground water indicate
the presence of contaminants above health based levels in the
deep aquifer before the five year review, this particular remedy
may be replaced by a treatment system. Additionally, if surface
water contaminant levels exceed State water quality standards
prior to the five year review, then a treatment system may
replace this remedy.
Date J
Valdas V. Adamkus /
Regional Administrator
U.S. EPA, Region//
-20-90
Date
Gerald L. Wille /
Oodniss ioner
Minnesota Pollution Control Agency
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PAGES DATE
270 90/10/00
591 90/10/00
337 90/10/00
66
14
15
90/10/16
90/10/00
90/10/00
165 90/11/28
90/12/00
ADMINISTRATIVE RECORD INDEX
OAK GROVE SANITARY LANDFILL
ANOKA COUNTY, MINNESOTA
TITLE
AUTHOR
Final MPCA,
Report Malcolm
Remedial Pirnie
Investigation
Appendices MPCA,
Remedial Malcolm
Investi- Pirnie
gation, Vol.
1 Of 2
Appendices MPCA,
Remedial Malcolm
Investi- Pirnie
gation, Vol.
2 Of 2
Final RI/ MPCA,
FS Reports Malcolm
for the Pirnie
Ground Water
Operable Unit,
Oak Grove
Sanitary Landfill
Proposed USEPA,
Plan for the MPCA
Ground Water
Operable Unit,
Oak Grove
Sanitary Landfill
Fact Sheet MPCA
for Oak
Grove Sanitary
Landfill
Ground Water
Transcript,
October 24,
1990, Public
Hearing
RECIPIENT
USEPA
DOCUMENT
TYPE NO
USEPA
Report/
Studies
Reports/ 2
Studies
USEPA
Reports/ 3
Studies
USEPA
Report/ 4
Studies
Public
Report
Public
Fact
Sheet
Court Public
Reporter
Responsive- MPCA
ness Summary
Public
Tran-
scripts
Report
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
Oak Grove Sanitary Landfill
Oak Grove Township, Anoka County, Minnesota
I SITE NAME. LOCATION AND DESCRIPTION
The Oak Grove Sanitary Landfill is located in Oak Grove Township,
Anoka County, Minnesota (figure 1) near the intersection of
Eidelweiss Street and County Road 22 (Viking Boulevard) as shown
in Figure 2. The site is approximately 38 miles northwest of St.
Paul.
The site encompasses approximately 104 acres, of which 45 have
been actively landfilled. The landfilled area of the site is
roughly rectangular in shape and extends to a maximum height of
approximately 50 feet above the grade elevation of the
surrounding areas. The topography of "the area immediately
surrounding the landfill is relatively level, with a maximum
relief of approximately 40 feet. The topography of the
surrounding area consists of low regions of uplands and sand
dunes interspersed among numerous lakes and wetlands. Elevations
vary from approximately 900 feet above mean sea level to
approximately 870 feet above mean sea level.
The site is located within the Cedar Creek watershed, an 85.9
square mile subwatershed of the Rum River drainage basin. Cedar
Creek, which at its nearest point is located approximately 3,000
feet south of the landfill, runs through the larger wetland
adjacent to the landfill and discharges to the Rum River
approximately two and a half miles southwest of the site.
Surface water runoff from the landfill drains generally southward
into the wetland.
The nearby developed land consists of agricultural and
residential property. The nearest residences include a home
within 300 feet along the western boundary and the residence and
facilities of the landfill owner along the northern boundary.
The total population estimated to reside within a four-mile
radius of the site is 9,821, while the total population estimated
to reside within a one-mile radius is 335. It is estimated that
well water is the drinking water supply for almost all of the
homes within the four-mile radius of the site. The remaining
residents are supplied by public or private utilities.
The site hydrogeology consists of 250 feet of sediments beneath
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the site which includes two aquifers separated by a semi-
.confining layer. The first aquifer is a shallow sand aquifer,
which ranges in thickness from 13.5 feet to 54 feet. Ground
water can be found at a depth ranging from 40 feet to near
surface in this particular aquifer. At the southern edge of the
landfill, the shallow sand aquifer is overlain by a peat deposit
and ground water is found within the peat. The shallow sand
aquifer is underlain by a layer of glacial till ranging in
thickness from 40 to 80 feet. This till has a lower hydraulic
conductivity than either of the two aquifers. Consequently, the
till acts as a semi-confining layer between the shallow sand
aquifer and the second aquifer which consists of an underlying
sand and gravel formation. This lower sand and gravel formation
is referred to as the valley train aquifer because it is
deposited within a bedrock valley. The valley train aquifer
extends to a depth of approximately 250 feet and is used
regionally for potable water that supplies many of the
residential wells in the area.
II SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Oak Grove Sanitary Landfill began operations in 1967 as an
open dump receiving mixed municipal and industrial solid waste.
A solid waste landfill permit was issued to the owner of the
site, Mr. Joseph Egan, in 1971 by the Minnesota Pollution Control
Agency (MPCA). In 1976, landfill operations were assumed by a
group of nine refuse haulers known as Northwest Disposal, Inc.
Landfilling operations ceased in January 1984, when the operating
license was suspended.
The landfill was filled from the center outwards in all
directions. It is estimated that currently there are at least
2.5 million cubic yards of waste in the landfill. Most of the
waste present in the landfill can be classified as commercial and
municipal solid waste. However, industrial solid and liquid
waste, some of which may be classified as hazardous, are also
present in the landfill. The wastes disposed of at the site are
believed to include at a minimum:
2,050 tons of acidic oil sludge;
1,225 tons of paint and solvent wastes;
unkown quantities of :
foundry sands and sludges,
inorganic acids,
metal sludges,
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chlorinated and unchlorinated organic compounds
from pesticide manufacturing,
cutting oils and lubricants,
cleaning solvents, and
inks.
The oil sludge was disposed of at the landfill between 1970 and
1975. It is believed that most of the oil sludge was placed in
what is currently the central portion of the landfill. The paint
and solvent wastes were landfilled during the same time period
and may have been placed in the same general area of the fill as
the oil sludge, however, the exact location of all these wastes
is unknown.
During the permitted operating period of the landfill, routine
inspections of the landfill were conducted at a frequency of two
or three times per month by the Anoka County Health Department
and also periodically by the MPCA. In 1983, Northwest Disposal,
Inc. submitted a permit application to expand the landfill. The
MPCA requested that additional soil and ground water data be
gathered for review of the application,-and the MPCA and the
Metropolitan Council also requested additional information be
gathered for preparation of an Environmental Impact Statement.
Stating that they were financially incapable of funding the
additional requested studies, Northwest Disposal did not further
pursue the proposed expansion permit and the landfill operating
permit was suspended in January 1984.
After disposal operations ceased at the landfill, Northwest
Disposal, Inc. requested permission from the MPCA to cover the
landfill with waste water treatment sludges (lime sludge)
generated by the St. Paul, Minnesota, Department of Public Works.
Permission was granted in March 1985 and the eastern two-thirds
of the landfill received the lime sludge. The calcium carbonate,
lime sludge was allowed to be used as a base material for the
final cover in an attempt to obtain proper closure of the site
under conditions of the permit. In November 1985 the MPCA
withdrew its permission to use the lime sludge when it was
discovered that the sludge was being stockpiled on top of the
landfill. Additionally, the lime sludge was not applied to the
landfill properly. As a result, water was ponding on the surface
of the landfill creating more environmental damage by generating
leachate and contaminated surface water run-off.
Previous investigations at the site included the first operable
unit study. The first operable unit addresses the source of the
contamination by containing the on-site wastes and contaminated
soil. The function of this operable unit is to provide a final
cover for the Oak Grove Sanitary Landfill which will prevent or
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minimize ground water contamination and risks associated with
exposure to the contaminated materials.
The United States Environmental Protection Agency (U.S. EPA) is
the lead agency with regards to enforcing the final remedy at
the site. Enforcement activities began with the issuance of
CERCLA 104(e) information request letters to numerous parties in
1986. Between 1986 and 1989 there was sporadic contact with a
small number of potentially responsible parties (PRPs) who were
connected with the site. In February 1989, U.S. EPA filed a lien
on the' property where the Oak Grove Sanitary Landfill is
situated. In May, 1939, a Final Demand of Payment of Site Costs
letter was sent to several PRPs. The purpose of the letter was
to recover costs incurred by the U.S. EPA for work performed at
the site. The letter was sent to fourteen PRPs most of whom were
past and current owner/operators and transporters. In the winter
and spring of 1990, additional CERCLA 104(e) information requests
were issued to a substantial number of individuals and companies.
U.S. EPA will next issue a Special Notice letter to the PRPs and
to other parties who may be potentially responsible at the site.
The purpose of this letter is to provide the PRPs with 90 days to
submit a good faith offer to U.S. EPA to implement remedial
action at the site. Failure on the part of the PRPs to negotiate
or submit a good faith offer to U.S. EPA can result in either a
CERCLA 107 enforcement action or a CERCLA 106 unilateral order.
U.S. EPA anticipates the issuance of these letters by February
1991.
Ill HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Remedial Investigation/Feasibility Study (RI/FS Report) and
the Proposed Plan for the Oak Grove Sanitary Landfill Site were
released to the public for comment on October 15, 1990. These
two documents were made available to the public in an information
repository maintained at the U.S. EPA Docket Room in Region V,
Chicago, Illinois. These documents were also maintained as part
of the administrative record at the following locations: Oak
Grove Township Hall located in Cedar, Minnesota; the St. Francis
Branch of the Anoka Public Library located in St. Francis,
Minnesota; and the Minnesota Pollution Control Agency located ir.
St. Paul, Minnesota.
The notice of availability for the RI/FS Report and the Propose:!
Plan was published in the October 11, 1990 edition of the Ano.Ma
County Union, the local newspaper. This notice also included a
news release which provided the dates of the public comment
period as well as the date of the public meeting. This news
release along with a fact sheet which described the preferred
alternative, was sent to all individuals on the Oak Grove site
mailing list. The mailing list includes interested residents,
township and county officials, elected officials, and site owner-
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and operators.
The public comment period originally began on October 15th and
ended on November 14, 1990. It was then extended till November
30, 1990. A response to the comments received during this period
as well as during the public meeting, is included in the
Responsiveness Summary, which is part of this Record of Decision.
This decision document represents the selected remedial action
for the Oak Grove Landfill site, in Anoka County, Minnesota,
chosen in accordance with CERCLA, as amended by SARA and, to the
extent practicable, the National Contingency Plan. The decision
for the site is based on the administrative record. A public
meeting was held on October 24, 1990 at the Andover Elementary
School. At this meeting, representatives from U.S. EPA, MPCA and
the Minnesota Department of Health answered questions about
problems at the site and the remedial alternatives under
consideration.
IV SCOPE AND ROLE OF OPERABLE UNIT WITHIN SITE STRATEGY
The remedy for the Oak Grove site has been divided into two units
or discrete actions, referred to as "operable units" (OU). They
are as follows:
OU One: Source control of contaminants from the
landfill.
OU Two: Remediation of contaminated ground water.
The first operable unit addressed the source control of
contaminants from the landfill by installing a final cover
system. A cover system will substantially reduce the amount of
surface water infiltration and hence leachate generation. By
installing a cover system U.S. EPA and MPCA intend that leachate
production will be decreased so ground and surface waters will no
longer be impacted by landfill contaminants contained within the
leachate.
The operable unit under consideration is Operable Unit Two:
Ground Water. The remedial action objectives for ground water
are two-fold. The first is to prevent significant impacts on
surface water from the discharge of contaminated shallow ground
water and to remediate the contaminated shallow ground water.
The Remedial Investigation (RI) report has determined that ground
water contained within the shallow aquifer discharges directly
into the surface water of the adjoining wetland. The ARARs for
the first objective are Maximum Contaminant Levels (MCLs) as
defined under U.S. EPA's Safe Drinking Water Act, MPCA surface
water quality standards for the Rum River watershed, and U.S.
EPA's Ambient Water Quality Criteria for Protection of Aquatic
Life (AWQCs). The second objective is to provide for continued
use of the deep valley train aquifer as a drinking water supply.
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The ARARs for the second objective are the MCLs. MPCA
Recommended Allowable Limits (RALs) were also considered in
determining the necessary clean up of the ground water at the
site.
Although ground water is the quantified pathway for contaminants
at the Oak Grove Sanitary Landfill, remedial action objectives
are defined for ground water and surface water. Each objective
is designed to meet the overall goal of protecting human health
and the environment. The alternatives under consideration
address ground water remediation. They are analyzed using U.S.
EPA's nine criteria, listed later in this document, for effective
Superfund action.
The remedial action for this second operable unit is consistent
with the action described in the September 1988 Record of
Decision (ROD). The September 1988 ROD addresses the source of
contamination by containing the on-site wastes and contaminated
soil with a capping system. This capping system when used in
conjunction with the ground water alternative selected in this
ROD, will comprise the final remedy for the site. Also, the
alternative selected will aid in the determination of the
effectiveness of the source control remedy. This is so because
the selected alternative involves the long-term monitoring of
sediments, surface and ground waters. Although remediation of
sediments was not the focus of this operable unit, results of tht_
RI/FS indicate that sediments may be impacted by the discharge of
ground water in the surface water at the site. Accordingly, the
selected alternative also includes long term monitoring of .
sediments to evaluate and refine any ecological risks posed by
such sediments.
V SUMMARY OF SITE CHARACTERISTICS
The U.S. EPA and the MPCA have determined that the Oak Grove
Sanitary Landfill contains hazardous substances and that the
potential exists for uncontrolled releases of these substances to
the environment. The primary route of contaminant migration fror.
the landfill appears to be ground water. The primary concern at
this site is the drinking water supply of private residences in
the vicinity of the landfill, all of which have private water
wells. Also of concern is the wetland bordering the southern
edge of the landfill, which may be an environmentally sensitive
receptor for the contaminants.
The site hydrogeology is defined by four types of deposits.
Three of these four ueposits comprise a shallow and deep aquifer
system, the remaining deposit acts as a semi-confining layer
between the two aquifer systems.
Across the southern portion of the site, peat deposits overlie a.
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outwash sand. The peat deposits are only a few feet thick and
are not laterally extensive across the entire site. The outwash
sand is present across the entire site and ranges in thickness
from 13.5 feet along the southern portion of the site to 54 feet
along the northern portion of the site. The outwash sand and
peat deposits comprise the first aquifer system, referred to as
the shallow sand aquifer. Ground water can be found at a depth
ranging from 40 feet to near surface in the outwash sand aquifer.
The outwash sand overlies a series of fine grain gray and red
till units ranging in thickness from 40 to 80 feet. This
material has a low hydraulic conductivity so it acts as a semi-
confining layer between the overlying shallow sand aquifer and
the underlying valley train deposits. The valley train deposits
are made up of sand and gravel. The valley train deposit was the
deepest unit investigated and it comprises the second, deep
aquifer system at the site. Local private well logs, all of
which are screened in this deep aquifer or lower, show this
aquifer to extend to a depth of at least 250 feet.
Figure 3 shows the locations of the monitoring wells used during
the RI. Figure 4 is a cross section from north to south across
the site illustrating the geology beneath the site.
The ground water flow beneath the site moves from a north to
south direction (Figure 5). There is a general downward,
vertical movement to ground water flow in the northern half of
the site and an upward, vertical movement to ground water once it
reaches the southern half of the site. Figure 6 illustrates the
vertical component of ground water as it moves from north to
south across the site. As can be seen, when ground water reaches
the southern half of the site, it discharges into the surface
water. This mechanism along with the semi-confining till layer,
inhibits the transport of contaminants from the shallow sand
aquifer to the deep valley train aquifer.
Based on the frequency of occurrence in both ground and surface
waters, concentrations, and health effects, the major
contaminants at the site are: arsenic, barium, benzene, 1,2-
dichloroethane, ethylbenzene, nickel, toluene, vinyl chloride,
and xylene. Virtually all of the contaminants are found only in
the shallow aquifer, along the southern side of the landfill.
The estimated dimensions for the shallow ground water plume are
20 feet deep, 1600 feet long and 200 feet wide. Estimates on the
volume range from 1 to 5 million gallons. Table 1 provides a
concise summary of all the contaminants detected at the Oak Grove
Site, the media they were detected in, the maximum value
detected, the frequency of detection, U.S. EPA's MCL and MPCA's
RAL for the contaminant.
The source of these contaminants appears to be the waste mass
contained in the landfill. All of these compounds except vinyl
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chloride are associated with petroleum based fuels and
lubricating oils, and are potentially present in a large volume
of oil sludge known to have been placed in the landfill. Vinyl
chloride is a degradation product of chlorinated ethanes such as
trichloroethene and dichloroethene which are wastes typically
found landfills. Vinyl chloride may also have been placed as a
waste in the landfill.
Contaminants were found in the surface water immediately south of
the landfill. The contaminants detected were chloroethane, 1,1-
dichloroethane, 1,2-dichloroethane, 1,2-dichloropropane, benzene,
ethylbenzene, xylenes, arsenic and barium, several of which are
major contaminants at the site. The levels at which these
contaminants were detected are below U.S. EPA AWQCs and MPCA
surface water quality standards. Leachate breakouts along the
southern slope of the landfill flow directly to the surface water
in the wetland. Shallow ground water also discharges to the
wetland, providing another source of contaminants to the
wetland's surface water and sediments. The high organic carbon
content of the peat adsorbing the organic contaminants and
volatilization of the organic contaminants appear to be effective
at limiting the migration of the contaminants. This is evidenced
by the limited size of the plume which extends approximately 400
feet from the toe of the landfill (Figure 7). This natural
attenuation process may also explain why contaminants found in
the surface water of the wetland are below MPCA surface water
quality standards and U.S. EPA (AWQCs). The MPCA surface water
quality standards for the site can be found in Table 2. The U.S.
EPA AWQCs can be found in Table 3. No contaminants appear to
have migrated to Cedar Creek located approximately 3000 feet fro-
the landfill.
Contaminants were found in the shallow sand aquifer immediately
downgradient and south of the landfill (Figure 8). Shallow
ground water contaminants include vinyl chloride, benzene,
ethylbenzene, toluene, xylene, 1,2-dichloroethane, arsenic,
barium and nickel. The following contaminants were detected at
levels which were at or above Federal and State drinking water
standards (MCLs & RALs): vinyl chloride, 1,2-dichloroethane,
benzene, arsenic and nickel. This shallow sand aquifer, however.
is not currently used for drinking water. The possibility exist-
that these contaminants may be present beneath the landfill ir.
the shallow aquifer, however, no wells have been installed
through the landfill to sample ground water underneath it. The
highest contaminant concentrations in the shallow aquifer were
found midway along the southern edge of the landfill. It is tr. :_
location where leachate seeps occur. These contaminant levels
may be the result of wastes which were placed in direct contact
with the water table.
Toluene, xylene, ethylbenzene, arsenic and barium were detectej
at low levels in the deep valley train aquifer. However, thes-.
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contaminants were found at levels one or more orders of magnitude
below Federal and State drinking water standards (MCLs and RALs).
Also, these contaminants were found in wells upgradient of the
landfill at concentrations similar to the concentrations found in
the wells downgradient of the landfill. Therefore, it has been
concluded that the low level contamination found in the deep
valley train aquifer is not attributable to the landfill.
The organic contaminants detected are all volatile organic
compounds (VOCs). These contaminants are volatilized to the
atmosphere via overland flow of surface water and discharge from
the shallow ground water aquifer to surface water. Once in the
atmosphere, VOCs are rapidly degraded by a combination of photo-
oxidation and hydrolysis. Organic compounds are not expected to
adsorb to soils. The peat, however, may adsorb some of the VOCs
due to its high organic carbon content.
Arsenic may be metabolized to organic arsenicals by a number of
organisms. This increases the mobility of arsenic compounds
and arsenic is recycled through the environment. The ultimate
fate of arsenic is probably the deep ocean, where it will be
persistent in the sediments.
Barium is extremely reactive, decomposes in water and readily
forms insoluble salts. Bioaccumulation is not a significant
process for barium.
Nickel is highly mobile in aquatic systems. Much of the nickel
entering the aquatic environment will be transported to the
oceans. Bioaccumulation is not a significant process for nickel.
VI SUMMARY OF SITE RISKS
Human Health Risk
The following contaminants were detected in the shallow aquifer:
vinyl chloride, chloroethane, 1,1-dichloroethane, 1,2-
dichloroethane, 1,2-dichloroethene, benzene, chlorobenzene,
ethylbenzene, r.oluene, trichloroethene and xylenes. A similar
complement of chemicals were detected in the surface water.
Surface water and ground water from the shallow aquifer are net
used for drinking water.
The contaminants detected in the valley train aquifer were
toluene, ethylbenzene, xylene, barium and arsenic. These
contaminants are present both upgradient and downgradient of the
site at similar concentrations which suggests that these
compounds may be "regional" or "background" contaminants. Grcur.j
water in the valley train aquifer is used for drinking water.
The human exposure pathways of concern at the Oak Grove Sanitar..
Landfill site are from ground water; exposure may occur from
drinking or non-drinking water use of the ground water. Expos-r-.
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from ingestion involves use of the ground water for drinking and
cooking; bathing may result in- skin contact; and inhalation
exposure to contaminants volatilized from the water may occur
during showering. The dermal and inhalation pathways are not
significant for the inorganics, as these contaminants are not
readily absorbed through the skin and are not volatile. Thus,
the ingestion pathway is considered for arsenic and barium only.
The monitoring data relevant for the human health risk assessment
are those values from wells screened in the deep valley train
aquifer. Consequently, the human health risk assessment was
determined using those contaminants which were detected in the
deep valley train aquifer (ethylbenzene, barium, toluene, xylene
and arsenic). This aquifer represents the potential potable
water supply. Since the pluiae from the landfill occurs only in
the shallow sand aquifer and there is an upward gradient causing
the shallow aquifer to discharge to surface water, and there is a
semi-confining layer between the two aquifers, there is no
pathway for contaminants in the shallow aquifer to reach the
potable water supply. Institutional controls already in place
will preclude the installation of any wells in the shallow
aquifer.
Arsenic is a carcinogen. Its carcinogenic effects were
determined using the exposure assumption of a 70 kg adult
drinking water from the deep valley train aquifer at a rate of
two liters per day, 365 days a year for a lifetime of 70 years.
The dermal route was calculated using a 70 kg adult showering 12
minutes a day, 365 days a year for 70 years.
Cancer potency factors (CPFs) have been developed by U.S. EPA's
Carcinogenic Assessment Group for estimating lifetime cancer
risks associated with exposure to potentially carcinogenic
chemicals. CPFs, which are expressed in units of mg/kg-day, are
multiplied by the estimated intake of a potential carcinogen, in
mg/kg-day, to provide an upper-bound estimate of the excess
lifetime cancer risk associated with exposure at that intake
level. The term "upper bound" reflects the conservative estimate
of the risks calculated from the CPF. Use of this approach makes
underestimation of the actual cancer risk highly unlikely.
Cancer potency factors are derived from the results of human
epidemiological studies or animal bioassays to which animal-tc-
human extrapolation and uncertainty factors have been applied.
Excess lifetime cancer risks are determined by multiplying the
intake level with the cancer potency factor. These risks are
probabilities that are generally expressed in scientific notation
(e.g. 10EE-6). An excess lifetime cancer risk of 1 X 10EE-6
indicates that, as a plausible upper bound, an individual has a
one in one million chance of developing cancer as a result of
site-related exposure to a carcinogen over a 70 year lifetime
under the specific exposure conditions at a site.
10
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The upper bound cancer risk due to the ingestion of ground water
from the valley train aquifer is 2- X 10EE-4, based on a maximum
arsenic value of 7.5 ppb. The MCL and RAL for arsenic, however,
is 50 ppb. The maximum value of arsenic detected is therefore an
order of magnitude less than the enforceable drinking water
standard.
Toluene, xylene, ethylbenzene and barium are not carcinogens but
can affect human health. The U.S. EPA has developed a standard
for measuring the potential for adverse health effects from
exposure to noncarcinogenic chemicals. This standard is called a
reference dose (RfDs). RfDs, which are expressed in units of
mg/kg-day, are estimates of lifetime daily exposure levels for
humans, including sensitive individuals. Estimated intakes of
chemicals from environmental media (e.g. the amount of a chemical
ingested from contaminated drinking water) can be compared to the
RfD. RfDs are derived from human epidemiological studies or
animal studies to which uncertainty factors have been applied
(e.g. to account for the use of animal data to predict effects on
humans). These uncertainty factors help ensure that the RfDs
will not underestimate the potential for adverse noncarcinogenic
effects to occur.
The RfD for toluene is 3 X 10EE-1 mg/kg-day. Xylene's RfD is 2 X
10EE mg/kg-day. Ethylbenzene has an RfD of 1 X 10EE-1 mg/kg-day.
Barium's RfD is 5 X 10EE-2 mg/kg-day.
Potential concern for noncarcinogenic effects of a single
contaminant in a single medium is expressed as the hazard
quotient (HQ) or the ratio of the estimated intake derived from
the contaminant concentration in a given medium to the
contaminant's reference dose. By adding the HQs for all
contaminants within a medium or across all media to which a given.
population may reasonably be exposed, the Hazard Index (HI) can
be generated. The HI provides a useful reference point for
gauging the potential significance of multiple contaminant
exposures within a single medium or across media.
The combined noncancer HI of toluene, xylene, ethylbenzene and
barium is 0.069 with the effects of barium predominant. The HI
is below U.S. EPA's recommended level of 1.0, indicating no
adverse effects are anticipated.
Ecological Risk
The potential ecological risks are posed via contaminated ground
water from the shallow aquifer discharging into the surface water
of the wetland. The scope of work for this operable unit was to
assess remedies for ground water contamination. During the RI it
was determined that a direct hydrologic connection exists betwe-:-.-.
the ground water in the shallow aquifer and surface water in t."-.~
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wetland.
As stated earlier an estimated 1 to 5 million gallons of
contaminated ground water is contained in the shallow aquifer.
The dimensions of this plume are 20 feet deep, 1600 feet long and
200 feet wide. Because the shallow aquifer is not used for a
potable supply of water its impact to human health was not
assessed. Consequently, the carcinogenicity of the various
contaminants found in the shallow aquifer were not determined.
What was determined in the RI/FS was the ecological risk
presented by shallow ground water contaminants discharging into
the surface water of the wetland.
Results from the RI indicate that the ecological risk from
volatile organic compounds in the surface water is low due to the
volatility of the compounds, their low concentrations, and low
bioaccumulation potential. Surface water contaminant levels in
the vicinity of the site are significantly lower than the fresh
water criteria and chronic toxicity values established under
MPCA's surface water quality criteria and U.S. EPA's AWQCs.
Limited historical data exists on surface water analyses.
Consequently, it was difficult to thoroughly evaluate the
environmental risks associated with surface water. However, the
alternative selected for this site provides for the collection
and analysis of surface water and sediment to further refine this
ecological risk.
VTI DESCRIPTION OF ALTERNATIVES
The alternatives under consideration for ground water
contamination were developed by examining a number of possible
remedial technologies and compliance of these alternatives with
applicable or relevant and appropriate requirements (ARARs) of
federal and state environmental statutes.
The goals of the remedial action are two-fold. The first is to
prevent significant impacts on surface water from the discharge
of contaminated ground water from the shallow aquifer into the
wetland, as well as clean-up of the shallow aquifer by preventing
the generation of leachate from the landfill and by natural
attenuation. The ARARs for this goal are the Maximum Contaminant
Levels (MCLs) under U.S. EPA's Safe Drinking Water Act, the MPCA
surface water quality standards and U.S. EPA's AWQCs.
The second goal of the remedial action is to ensure continued use
of the deep valley train aquifer as a drinking water supply. The
ARARs for this goal are the Maximum Contaminants Levels (MCLs)
under U.S. EPA's Safe Drinking Water Act. The combined noncancer
hazard index is below U.S. EPA's recommended level of 1.0,
indicating that no adverse effects are anticipated from the
consumption of ground water from the deep valley train aquifer.
12
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Additionally, the highest concentration of arsenic found in a
downgradient well was 7.5 ppb. Arsenic is a known carcinogen and
has an MCL of 50 ppb. The RAL for arsenic is also 50 ppb.
A total of four alternatives were evaluated in detail for
remediating ground water. Each alternative was evaluated in
conjunction with the final cover system which was defined in the
September 1988, ROD. The alternatives analyzed are as follows:
Alternative 1: No action.
Alternative 2
Alternative 3
Alternative 4:
Long term monitoring of the shallow
sand aquifer, surface water and
sediments; institutional controls;
and natural attenuation.
Long term monitoring of the shallow
sand aquifer, deep valley train
aquifer, surface water and sediments;
institutional controls; and natural
attenuation.
Pump and treat the shallow sand
aquifer, plus long term monitoring of
the deep valley train aquifer, surface
water and sediments; institutional
controls; and natural attenuation.
ALTERNATIVE 1: NO ACTION.
Capital Cost: $0.
Annual Maintenance and Monitoring Cost:
Estimated Present Worth: $0.
$0.
The Superfund program requires that the "no action" alternative
be evaluated at every site to establish a baseline for
comparison. Under this alternative, no further action would be
taken to remediate or monitor ground water.
ALTERNATIVE 2: LONG TERM MONITORING OF SHALLOW SAND AQUIFER,
SURFACE WATER AND SEDIMENTS.
Capital Cost: $40,000.
Annual Maintenance and Monitoring Costs:
Estimated Present Worth: $700,000.
$80,000 for the first
year and $60,000 for
subsequent years.
The second alternative involves monitoring ground water quality
at selected wells in the shallow sand aquifer, monitoring surface
water quality, analysis of sediment samples, implementing
institutional controls concerning placement of drinking water
13
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wells, abandoning non-essential wells and natural attenuation of
shallow ground water to reduce concentrations of contaminants to
levels which satisfy ARARs. The institutional controls
referenced, are found under Minnesota Rule., Chapter 4725.
Chapter 4725 governs where drinking water wells can be placed.
It states that drinking water wells can not be located in an area
between a landfill and point of ground water discharge to a
surface water source and that drinking water wells can not be
placed where the possibility of intercepting leachate exists.
Another component of this alternative involves the monitoring of
existing wells and surface water for volatile organic compounds,
pesticides, PC3s, arsenic, barium, nickel, zinc and nutrient
parameters. Sediment samples would be analyzed for arsenic,
barium and nickel. A minimum of eight shallow wells would be
monitored. Surface water monitoring points would be established
based on a conductivity survey. Sediment samples would be
collected at the surface water monitoring points. The monitoring
program would consist of sampling sediments, ground and surface
waters at a frequency of three times per year for the first year
and semi-annually thereafter.
ALTERNATIVE 3: LONG TERM MONITORING OF SHALLOW SAND AQUIFER,
DEEP VALLEY TRAIN AQUIFER, SURFACE WATER AND SEDIMENTS.
Capitol Cost: $40,000.
Annual Maintenance and Monitoring Costs: $90,000 for the first
year and $70,000 for
subsequent years.
Estimated Present Worth: $300,000.
Alternative 3 adds long terra monitoring of the deep valley train
aquifer. Selected wells in the shallow and deep aquifers and
surface water will be monitored for volatile organic compounds,
arsenic, barium, nickel, zinc, pesticides, PCBs and nutrient
parameters. Sediments would be analyzed for arsenic, barium and
nickel. Chapter 4725 of Minnesota State Law concerning the
placement of drinking water wells, will be implemented and non-
essential wells will be abandoned. Natural attenuation would
continue to take place on the shallow ground water to reduce
concentrations of contaminants to levels which satisfy ARARs. A
minimum of twelve shallow and deep wells would be monitored.
Surface water monitoring points would be established based on a
conductivity survey. Sediment sample points would be located
where surface water sampling occurs. The monitoring prograr.
would consist of sampling sediments, ground and surface waters at
a frequency of three times per year for the first year and ser.i-
annually thereafter.
ALTERNATIVE 4: PUMP AND TREAT SHALLOW SAND AQUIFER; LONG TEE,V.
MONITORING OF VALLEY TRAIN AQUIFER, SURFACE WATER AND SEDIMENT:.
14
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Capitol Cost: $1,000,000.
Annual Maintenance and Monitoring Costs: $250,000.
Estimated Present Worth: $3,400,000.
Alternative 4 involves the installation of approximately eight
pumping wells spaced at 200 feet intervals. The composite
discharge would be approximately 100 gpm. Onsite treatment would
consist of oxidation of organics by an advanced oxidation process
and precipitation of inorganics with specialized polymers. Ion
exchange polishing may be required to remove barium and
beryllium. Sludge may require stabilization -prior to dewatering
and disposal in a landfill. Treated water would be discharged to
Cedar Creek. This evaluation also includes monitoring of the
deep valley train aquifer and surface water, sediments; State
Law, Chapter 4725 institutional controls and abandonment of non-
essential wells. The parameters to be monitored for in the deep
aquifer, surface water and sediments along with their frequency,
would be the same as those described in Alternative 3. A total
of four existing deep valley train aquifer wells would be
monitored. Surface water monitoring points would be based on a
conductivity survey. Sediment samples would be collected at
surface water monitoring points.
VIII SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The National Contingency Plan and Section 121 of the Superfund
Amendments and Reauthorization Act of 1986 (SARA) form the
regulatory basis for the nine evaluation criteria to be utilized
in determining the appropriate remedial action at a CERCLA site.
Specifically, Section 121 of SARA requires that the selected
remedy is to be protective of human health and the environment,
cost-effective, and use permanent solutions and alternative
treatment technologies or resource recovery technologies to the
maximum extent practicable.
The following is a summary of the nine evaluation criteria used
to evaluate remedial alternatives:
Overall Protection of Human Health and the Environment
addresses whether or not a remedy provides adequate
protection and describes how risks are eliminated,
reduced or controlled through treatment, engineering
controls, or institutional controls.
Compliance with ARARs addresses whether or not a remedy
will meet all of the applicable or relevant and appro-
priate requirements of other Federal and State environ-
mental statutes and/or provide grounds for invoking a
waiver.
Long-term Effectiveness and Permanence refers to the ability
of a remedy to maintain reliable protection of human healtr.
15
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and the' environment: over time once cleanup goals have been
met.
Reduction of Toxicity. Mobility, or Volume through Treatment
is the anticipated performance of the treatment technologies
that may be employed in a remedy.
Short-term Effectiveness refers to the speed with which the
remedy achieves protection, as well as the remedy's potent-
ial to create adverse impacts on human health and the envi-
ronment that' may result during the construction and imple-
mentation period.
Implementabilitv is the technical and administrate. feasi-
bility of a remedy, including the availability of materials
and services needed to implement the chosen solution.
Cost includes capital, operation and maintenance costs.
State Acceptance indicates whether, based on its review of
the Remedial Investigation, Feasibility Study and Proposed
Plan, the State concurs with, opposes, or has no comment on
the preferred alternative.
Community Acceptance indicates the public support of a give-
alternative. This criteria is discussed in the Responsive-
ness Summary.
Overall Protection of Human Health and the Environment
Alternative 1 may be protective of v.uman 3alth and the
environment because source control ^asur 3 are being implemented
under the 1988 ROD, natural attenuation i. reducing contaminants
in the shallow aquifer and contaminant levels in the valley train
aquifer and surface water are below applicable or relevant and
appropriate standards. .While the shallow aquifer is not a
current drinking water source, and the site geological
characteristics indicate contaminants will not migrate to the
deep aquifer, the deep aquifer is a drinking water source.
The long-term monitoring described in Alternatives 2 and 3 will
provide information on whether or not contaminant concentrations
in ground water in the valley train aquifer and surface water
continue to be within acceptable human health and environmental
standards. With a long-term monitoring alternative, contaminants
may continue tc migrate to surface waters and potentially
accumulate in tne adjacent wetlands. However, surface and ground
water quality will liXely improve in the long-term as leachate
generation is decrea: i due ~o the Construction of the final
cover system. These eachate seep are tr.e primary cause of
shallow ground water .ind surface water contamination.
Additionally, the wetland peat deposits act as a filter for the
16
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organic contaminants thereby reducing contamination in the
shallow aquifer via natural attenuation. The high organic carbon
content of the peat captures and absorbs the contaminants from
the shallow ground water as it discharges into the surface water
of the wetland. The inorganic contaminants, as determined in the
RI/FS, have a low potential for bio-accumulation in the wetlands.
Thus, contamination in the shallow aquifer is being reduced via
natural attenuation. As a result of this natural attentuation,
U.S. EPA and MPCA believe contaminants in the shallow aquifer
will be reduce to the levels required by MCLs in a timeframe
comparable to that which could be achieved through active
remediation. Long term monitoring of the shallow aquifer will
provide further information regarding the effectiveness of this
treatment.
Alternative 4 provides the maximum protection of the four
alternatives because contaminants are removed and treated.
Alternatives 2, 3, and 4 will also reduce risks through the
implementation of institutional controls. Specifically, those
which are found under-Minnesota Rule, Chapter 4725. Under this
provision, it is recommended that drinking water wells not be
located in an area between a landfill and point of ground water
discharge to a surface water source. Consequently, drinking
water wells can not be installed on the downgradient side of the
Oak Grove Sanitary Landfill within the shallow ground water
plume. Subpart 2 of Chapter 4725 also states that any well which
intercepts leachate from a landfill can not be used for potable
water. This institutional control ensures that the shallow
ground water contaminated by leachate from the Oak Grove Sanitary
Landfill can not be used for drinking water.
Compliance with ARARs
Section 121 (d) of Sara requires that remedial actions meet
legally applicable or relevant and appropriate requirements
(ARARs) of other environmental laws. These laws may include:
the Resource Conservation and Recovery Act (RCRA), the Clean
Water Act (CWA), the clean air act (CAA), the Safe Drinking Water
Act (SDWA), and any state law which has more stringent
requirements than the corresponding Federal law. "Legally
applicable" requirements are those cleanup standards, standards
of control, and other substantive environmental protection
requirements, criteria or limitations promulgated under Federal
or State law that specifically address a hazardous substance,
pollutant, contaminant, remedial action, location, or other
circumstances at a CERCLA site. "Relevant and appropriate"
requirements are those requirements that, while not legally
applicable to the remedial action, address problems or situations
sufficiently similar to those encountered at the site that their
use is well suited to the remedial action.
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Non-promulgated advisories or guidance documents issued by
federal or state governments do not have the status of ARARs;
however, where no applicable or relevant and appropriate
requirements exist, or for some reason may not be sufficiently
protective, non-promulgated advisories or guidance documents may
be considered in determining the necessary level of clean up for
protection of human health and the environment.
The selected alternative calls for long term monitoring and the
use of institutional controls. The following is a description of
the ARARs for the selected remedy and an explanation of how this
remedial action meets these requirements.
It is the policy of U.S. EPA to evaluate the appropriate
remediation of ground water based upon U.S. EPA's Ground Water
Protection Strategy. See 55 Fed. Reg. 8732, March 8, 1990. This
policy establishes different degrees of protection for ground
water based on their vulnerability, use and value. Pursuant to
the Ground Water Protection Strategy, the ground water located in
both the shallow and the valley train aquifers are classified as
Class I or Class II ground water. At this site, preliminary
remediation goals for Class I and II ground waters are set at
Maximum Contaminant Levels (MCLs) under the Federal Safe Drinking
Water Act.1
The Safe Drinking Water Act of 1974 (SDWA), as most recently
amended in 1986, requires the establishment of standards to
protect human health from contaminants in drinking water.
Maximum contaminant levels (MCLs) for specific contaminants have
been promulgated under the SDWA. [CERCLA §121(d)(2)(A)(i)
requires on-site CERCLA remedies to attain MCLs where they are
applicable or relevant and appropriate.] Pursuant to the Ground
Water Protection Strategy, MCLs are relevant and appropriate fcr
the shallow aquifer and the valley train aquifer at the site.
Minnesota Rules Chapter 7035.2815, Subpart 4 similarly provide
ground water protection standards at solid waste treatment,
storage and disposal facilities. These standards, called
intervention limits (ILs), are not applicable because the
landfill was filled prior to the effective date of the ILs.
While ILs are relevant because they pertain to landfills, they
For purposes of this Record of Decision, U.S. EPA and
MPCA have not found it necessary to determine whether
the shallow aquifer may be considered. Class III group.::
water due to the presence of contaminants not related
to the landfill. In the event that the remedial
measures authorized for this site do not achieve SWDA
levels, U.S. EPA and MPCA will reconsider this classi-
fication to determine whether furhter remedial acticr.
is required.
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are not appropriate because they were set at such levels as only
those landfills designed in accordance with recent regulations
and technology can meet.
The Minnesota Department of Health has established health based
criteria for contaminants in drinking water referred to as
Recommended Allowable Limits (RALs). These RALs are not ARARs
because they are not promulgated; however these criteria have
been considered, and U.S. EPA and MPCA have determined that all
of the alternatives satisfy the RALs.
Regarding surface waters, the Federal Clean Water Act (CWA), 33
U.S.C. Sections 1251, et seq.. as amended, requires USEPA to
establish water quality criteria (AWQC) for bodies of water based
on effects of pollutants on human health and aquatic life and on
the potential or designated uses of the waters. Federal AWQC are
non-enforceable guidelines used by States to set water quality
standards for surface waters, as required under Section 303 of
the CWA. AWQC may be relevant and appropriate to cleanup of
surface and ground water at CERCLA sites. See CERCLA Section
121(d)(2)(B)(i).
CERCLA remedial actions involving surface bodies of water must
also ensure that applicable state water quality standards are
met. Minnesota has existing surface water quality standards for
the Rum River watershed. See MN Rules, Chapter 7050. The
existing water quality standards are applicable.
The selected remedy will satisfy all ARARs and will be protective
of human health and the environment. Ground water in the valley
train aquifer and surface water meet or exceed ARARs.
Contaminant levels in the shallow aquifer do not currently
satisfy ARARs, however, construction of the landfill cap, in
conjunction with natural attenuation will reduce contaminants to
concentrations consistent with ARARs within a timeframe
comparable to that which could be achieved through active
remediation. Additionally, the selected remedy is in compliance
with 40 CFR Part 6, which concerns protection of wetlands. In
keeping with Part 6, the selected remedy will avoid adverse
impacts associated with the destruction or loss of the wetlands
^nd will not support new construction in the wetlands.
Alternatives 1, 2 and 3 meet MPCA surface water quality standards
for the Rum River watershed. Long-term monitoring will provide a
direct indication that remedial action criteria are achieved.
Alternative 4 meets MPCA surface water quality standards,
although construction requirements may require a waiver of
wetlands regulations.
All the alternatives proposed for the Oak Grove Sanitary Landf::.
site meet or exceed ARARs.
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Long-term Effectiveness and Permanence
Alternatives l, 2 and 3 do not increase the magnitude of residual
human health risk because human contact is minimized by site
access controls included under the cover system operable unit. A
cover will also reduce the likelihood of leachate seeps
occurring. These leachate seeps are the primary cause of shallow
ground water and surface water contamination. Contaminants
present in the shallow ground water and surface water do not
appear to be migrating into the deep valley train aquifer. Water
quality will likely improve in the long-term as a result of a
final cover system. Long-term monitoring alternatives (2 & 3)
will determine the need for additional future actions.
Alternative 4 is effective because organic contaminants are
removed from ground water and destroyed. Inorganic compounds are
removed and the -resultant sludge is taken to a permitted facility
for long-term management.
Reduction of Toxicity, Mobility and Volume
Alternative 4 provides reduction of toxicity, mobility and volume
of site contaminants. Organic compounds are destroyed. The
toxicity and mobility of inorganic compounds are reduced by
chemical and physical processes during treatment.
Alternatives 1, 2 and 3 allow a limited reduction of contaminant
toxicity and mobility due to the natural adsorption and
degradation occurring in the wetlands. An organic system exists
at the site which appears to be reducing the volume and toxicity
of the contaminants via natural attenuation. Specifically, the
peat deposits found in the wetland act as a filter. The high
organic carbon content of the peat filters and absorbs organic
contaminants from the shallow ground water as it discharges into
the surface water of the wetland. Also, additional treatment
occurs as organic compounds volatilize once they enter the
surfaco water.
U.S. EPA's and MPCA's reliance on natural attenuation does not
imply thet the ground water will not be cleaned up. Instead
biodegradction, dispersion, dilution and adsorption will
effectively reduce contaminants in the ground water to a
protective levtjl in a timeframe comparable to that which could be
achieved through active restoration. Additionally, institutional
controls will be used at the site to ensure that ground water is
not used before levels protective of human health and the
environment are reached.
In addition to the natural attenuation process occurring at the
site and the institutional controls, the final cover system will
reduce the volume and mobility of leachate produced. The
monitoring of surface water and the shallow sand aquifer will
20
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confirm or negate the effectiveness of the final cover system.
Short-term Effectiveness
Alternatives 1, 2 and 3 are likely effective in the short-term
because site access is controlled under the cover system operable
unit. Specifically, a fence will be installed as part of the
final cover system. Minimal risk to workers and the public will
result from monitoring activities. Short-term impacts on worker
health and safety are possible under Alternative 4 because
treatment plant workers are required to handle caustic chemicals
and inorganic treatment sludges.
Implementafcility
Alternatives 1, 2 and 3 are implementable because ground water
will be' monitored using existing wells. Surface water monitoring
stations will be established using a conductivity survey.
Alternative 4, however, will be difficult to implement without
destroying portions or the wetland by pumping.
Cost
The present worth cost range of the alternatives are as follows:
Alternative 4: $3,400,000
Alternative 3: $800.000
Alternative 2: $700,000
Alternative 1: $0
State Acceptance
U.S. EPA and MPCA agree on the preferred alternative. Both
Agencies have been involved in the technical review of the
Remedial Investigation Report, Feasibility Study (RI/FS) and the
development of the Proposed Plan and the ROD.
Community Acceptance
Community acceptance is assessed in the attached Responsiveness
Summary. The Responsiveness Summary provides a thorough review
of the public comments received on the RI/FS and Proposed Plan,
and U.S. EPA's and MPCA's responses to the comments received.
TY SFT.FCTED REMEDY
The U.S. EPA and MPCA each independently select Alternative 3 as
the most appropriate alternative for ground water remediation at
the Oak Grove Sanitary Landfill site. Alternative 3 involves
the long-term monitoring of the shallow sand aquifer, the deep
valley train aquifer, surface water and sediments; institutional
controls concerning the placement of wells drinking water wells:
21
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and natural attenuation.
Alternative 3 is implementable and provides a direct indication
that surface water quality standards are being met. Additionally,
Alternative 3 monitors both aquifers to ensure that continued use
of the deep valley train aquifer as a potable water supply may
continue.
Finally, the natural filtering process of ground and surface
waters by on-site peat deposits provides a mechanism for
satisfying ARARs for the shallow aquifer and substantially
reducing risk via treatment. Institutional controls regarding
placement of drinking water wells are in place at the site which
provides an additional reduction of risk to human health.
The combination of Alternative 3 and the final cover described in
the September 1988 ROD, would provide a substantial risk
reduction through containment of wastes and contaminated soils.
The risk assessment has concluded that potential human health
risks could occur via the ground water ingestion pathway. Ground
water from the deep valley train aquifer is used for drinking
water. However, no contaminants were found in the deep valley
train aquifer which exceeded U.S. EPA's MCLs or MPCA's RALs
contaminants from ground water in the shallow aquifer are being
treated via natural attenuation. The potential ecological risks
are posed via contaminated, shallow ground water discharging into
the adjacent surface water. Compounds found in surface water
near the site are significantly lower than the fresh water
criteria and chronic toxicity values established under the State
of Minnesota's Surface Water Quality Criteria. Monitoring of
sediments, surface and ground waters will assure that these
remediation goals are not being exceeded.
The monitoring system described in Alternative 3 will also
determine the effectiveness of the selected cover system in
protecting ground and surface water quality at the site as well
as monitor the effectiveness of the natural attenuation process.
Alternative 3 will establish a data base of sediment, ground and
surface water analytical results which would be used in the five
year review of the final covor remedy. Also, if future
analytical results reveal contaminants exceeding health based
levels in the deep aquifer or if surface water contaminant
levels exceed State water quality standards then this long-term
monitoring remedy may be replaced by a treatment system. This
replacement of remedies may occur prior to the five year review.
With regards to cost, Alternative 3 provides the best overall
effectiveness proportional to its costs. Alternative 3 has an
estimated present worth of $800,000. The initial capitol cost is
$40,000 with annual operational and maintenance costs being
$90,000 for the first year and $70,000 for subsequent years.
22
-------
Therefore, the selected alternative is believed to provide the
best balance of trade-offs among the alternatives with respect to
the nine evaluation criteria. Based on the information available
at this time, U.S. EPA and MPCA believe the selected alternative
would be protective of human health and the environment, would
comply with ARARs, would be cost effective, and would utilize
permanent solutions when used in conjunction with the final cover
system defined in the September 1988 ROD.
X STATUTORY DETERMINATIONS
Protection of Human Health and the Environment
The selected remedy is protective of human health as there is
little opportunity for contact with contaminated shallow ground
water. Ground water in the shallow sand aquifer is not used for
potable water, and U.S. EPA and MPCA believe that ground water in
the shallow aquifer will be effectively remediated via natural
attenuation and construction of the landfill cap. Ground water
in the deep valley train aquifer, however, is used for potable
water. No contaminants were found in the deep valley train
aquifer which exceeded U.S. EPA MCLs or MPCA RALs. The results
of the RI/FS indicated that contamination from the shallow
aquifer does not enter into the lower, deep valley train aquifer.
This condition exists due to an upward gradient present in the
shallow aquifer system.
The preferred alternative, Alternative 3, will ensure that ground
water in the deep valley train aquifer can continue to be used as
a potable watef supply. Monitoring results from the deep valley
train aquifer, will also be used to develop a data base of ground
water quality at the site. This data base will be used in the
five year evaluation of the final cover system as well as to
determine if a treatment remedy needs to be implemented prior to
the five year review.
Contaminated ground water from the shallow sand aquifer
discharges into the adjacent surface water. Compounds found in
the surface water are lower than U.S. EPA AWQCs and MPCA surface
water quality criteria. Alternative 3 is protective of the
environment because long-term monitoring of the surface water and
sediments will assure that Federal and State surface water
quality standards aren't being exceeded and bio-accumulation of
compounds in the sediments isn't occurring. Analytical results
from this monitoring will also be used in the five year
evaluation of the final cover system and in the determination of
whether or not to implement a treatment system prior to the five
year review. No unacceptable short term risks or cross media
impacts will be caused by implementation of the selected remedy.
Attainment of Applicable or Relevant and Appropriate Requirements
23
-------
Alternative 3 meets all applicable and relevant and appropriate
requirements (ARARs) of Federal and more stringent State
environmental laws. The pertinent ARARs for this remedial actio.
are the MCLs established under the Federal Safe Drinking Water
Act; surface water quality standards under Minnesota Rules,
Chapter 7050; and Federal Ambient Water Quality Criteria for
Protection of Aquatic Life (AWQCs). The Land Disposal
Restrictions of RCRA do not apply to this remedial action because
no RCRA hazardous wastes are being generated as a result of this
remedy.
The deep valley train aquifer is a source of potable water. The
shallow sand aquifer is not used for drinking water. The
objective of the remedial action is to allow continued use of the
deep valley train aquifer as a drinking water source. Any
contaminant found in this lower aquifer must be at a level which
is lower than or equal to those values established under the U.S.
EPA's Safe Drinking Water Act. Compounds found in the deep
valley train aquifer are below these standards.
Ground water contained in the shallow sand aquifer, discharges
into the surface water downgradient from the site. Contaminants
found in the surface water are below the fresh water criteria and
chronic toxicity values established under Chapter 7050 Minnesota
Rules as well as below those levels recommended in the Federal
AWQCs.
Cost Effectiveness
The selected remedy is cost-effective because it has been
determined to provide overall effectiveness proportional to its
costs, the net present worth value being $800,000. The selected
remedy is the second most expensive alternative; however, it is
the most consistent with the overall site strategy for
remediating ground and surface waters.
Utilization of Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the Maximur.
Extent Practicable
U.S. EPA and the State of Minnesota believe the selected remedy
when used in conjunction with the final cover system described in
the September 1988 ROD, represents the maximum extent to which
permanent solutions can be utilized in a cost-effective manner
for the final remedy at the Oak Grove Sanitary Landfill site. cf
the alternatives that are protective of human health and the
environment and comply with ARARs, U.S. EPA and the State have
determined that the selected remedy provides the best balance cf
tradeoffs in terms of long-term effectiveness and permanence,
reduction of toxicity, mobility or volume, short-term
24
-------
effectiveness, implementability , cost, also considering the
statutory preference for treatment as a principal element and
considering State and community acceptance.
on the results of the RI/FS, a pump and treat ground water
extraction system is not warranted at this time. Ground water in
the deep valley train aquifer is not contaminated to the extent
that it can not be used' as a potable water supply. Ground water
in the shallow sand aquifer is not used for drinking water and
discharges into the adjacent surface water. Contaminants found
in the surface water are below enforceable levels. If future
analytical results indicate the presence of contaminants above
health based levels in the deep aquifer, this particular remedy
may be replaced by a treatment system. Additionally, if
contaminant levels in the surface water increase to a level above
State water quality standards or U.S. EPA AWQCs then this remedy
may require a treatment system.
The selected alternative is therefore considered to be the most
appropriate solution to ground water contamination at the site
because it provides the best trade-offs with respect to the nine
criteria and represents .the maximum extent to which permanent
solutions and treatment are practicable.
Preference for Treatment as a Principal Element
Based on the results of the RI/FS, artificial treatment of ground
water to permanently and significantly reduce toxicity, mobility,
or volume of contaminants was not found to be necessary to
protect human health and the environment, or to be practicable at
the site at this time. However, if future analytical results
indicate the degradation of surface and potable ground water to
levels which are not protective of human health or the
environment, then this remedy may have to be modified to include
a treatment system.
XI DOCUMENTATION OF SIGNIFICANT CHANGES
No significant changes have been made since the publication of
the Feasibility Study or Proposed Plan.
25
-------
OAK GROVE
LANDFILL
N
NOT TO SCALE
ief: IT Corp. 19S7b.
MALCOLM
PIRNIE
GENERAL SITE LOCATION MAP
OAK GROVE SANITARY LANDFILL Rl
-------
7?* . f -
J •*-»;•:
/£ -
Ref: Cedar, Minnesota USGS 7.5 Minute
(Topographic) Quadrangle
N
2?
2000
SCALE IN FEET
4000
MAU3OLM
PIRNIE
SITE LOCATION MAP
OAK GROVE SANITARY UVNDFILL Rl
-------
' iV,-'i
j^HaE&y \"i. I
MW 306
MW 606
MW 401
IRNI
SOIL BORING AND MONITORING WELL LOCATIONS
fT CORPORATION AND MALCOLM PIRNIE. INC. REMEDIAL INVESTIGATIONS
OAK GROVE SANfTARY LANDFILL Rl
-------
c
AW-504
(uw.jruo dom 010 S4 n\
UJ
C '
AV-1,03
OUTUASM
COARSE RED TILL
f/fi/f /?£O r/LL
VALLKY TRAIN
IStND t CBIkVCI.I
««*/f»M
4>ll«»
-------
REGIONAL SHALLOW GROUND WATER FLOW
OAK GROVE SANITARY LANDFILL Rl
FIGURE 5
-------
NORTH
SOUTH
MW-504
z
o ...
MW !>03
PEAT
EOUIPOTENTIAL UNE
GROUND WATER
FljOW LINE
Notes: Equ*r«i»"tlii Una held vtktes pretamcd In (Mt. MSL.
Dm from Round 3 (Novwntwr. 1989) Mmp«ng even!
HORIZONTAL SCAIE
0 100 ?00 400 left
t^"^^»»»«^^""^™^**^
MAIOXM
PIRNIE
GENERALIZED HYDROGEOLOGIC CROSS-SECTION
OAK GROVE SANITARY LANDFILL Rl
FIGURE 6
-------
=r:^C^.: S-L_.'' ^N^;i=5r^S!
APPROXIMATE EXTENT OF
SURFACE WATER CONTAMINATION
V i
APPRCX1MA TE P'lCPEFirr BOUNDARY
,M y/t
SCALE
400
-N-
800 feet
PIRNIE
APPROXIMATE EXTENT OF
SURFACE WATER CONTAMINATION
OAK GPOVE SANITARY LANDFILL Rl
Z 7
-------
^ s
APPROXIMATE EXTENT OF: )
GROUND WATER CONTAMINATION
APPRO JOJUA rr PFKIPt -RTY BOUNDAfl Y
SCALE
200 400
800 feet
-N-
P1RNIE
APPROXIMATE EXTENT OF
GROUND WATER CONTAMINATION
OAK GROVE SANITARY LANDFILL Rl
FIGl-RE ?
-------
TABLE 1
SUMMARY OF CONTAMINANT OCCURRENCE
OAK GROVE SANITARY LANDFILL Rl
FREQUENCY OF DETECTION
COMPOUND ^ROUND-
WATER
I
Vinyi Chlorida
C.*iioro»in«n«
1 ,2-Oichloro«Ui«n«
B«nz»n«
Ac«y1t>»ni»n«
M«triyi«n« Cnlorid*
To4u«n«
Xy1«n«»
A/Mnic
3/39
10/75
«/73
14/75
1/7-5
19/75
40/75
23/75
27/75
43/76
SURFACE
WATER
0/4
4/11
2/11
1/11
2/11
1/11
7/11
1/11
1/11
4/11
SS3IMEN7
OM
via
one
one
16/14
via
V4/ie
ana
:na
12/18
SOILS
NA
0/21
0/21
0/21
11/21
1/21
a/21
3/21
2/21
11/12
MAXIMUM
VALUE
DETECTED
12 ug/L
NO
NO
NA
ffio ug/L
170 ug/U
140LKJ/T.
NO
a.S ug/L
23u«n.
NO
NO
20 ug/L
24 ug/L
NO
NO
31 ug/L
1500 ug/L
la.OOOug/Vg
12OOugAg
CZugA.
25 ug^.
110 ug/kg
23 ug/Vg
25ugA.
110 ug/L
MO ug/kg
37 ugAg
54 ug/L
45 ug/L
440ugAg
110 ugAg
10* ug/L
Kug/L
lOOOugAg
21 ug/Vg
212ugA.
10 ug/L
4.1 mgAg
19 mg/Vg
RAJ."
(ugrt)
0.15
NA
3.«
7
700
080
48
2420
400
SO
MCL'
(ug/i)
^ {
NA
5
5 '
NA
700.,pi
NA
ZOOCHpl
IO.OOnm*n4«4 AII
-------
TABLE 1
SUMMARY OF CONTAMINANT OCCURRENCE
OAK GROVE SANITARY LANDFILL Rl
COMPOUND
Barium
Nickel
-
i . 1 -Oicnkxo«m«n«
TouJ 1 ,2-Oichioro»th»n«i
Trtn»-1 ,2-Oichloro«(n«n«
Chloroform
Bromodichlorom«tnan«
1 _2-Oichloro(xop«n«
Tricolor o»tnyl»n«
4-»..«my1-2-P»nUAon»
FREQUENCY OF DETECTION
GROUND-
WATER
50/T5
one
13/75
7/38
4/36.
0/75
0/75
2/75
3/75
0/75
SJVACE
w, -TEH
5/11
3/7
3/16
1/10
1/16
0/16
0/16
1/16
2/16
1/16
SEDIMENT
10/16
an 2
0/11
0/11
0/11
1/11
0/11
0/11
0/11
3/16
SOILS
1/12
12/12
0/21
X*
0/21
1/21
2/21
1/21
0/21
0/21
0/21
MAXIMUM
VALUE
DETECTED
3S30ug/L
l740ug/L
118 mg/kg
74 mg/kg
223ug/L
fl6ug/L
2.5 ing/kg
50 mg/kg
7ugVI
65ug/1
ND
NO
21 ug/l
2ug/l
NO
NO
6.7ug/
I2ug/1
NO
13mg/kg
NO
NO
SmgAg
78 mg/kg
NO
NO
NO
6 mg/kg
lug/1
5ug/l
NO
NO
1 ug/l
3^ug^
NO
NO
NO
160 ug/l
fleOmgAg
NO
RAL"
(ug/1)
15OO
ISO
• 10
70
57
140
6.6
31
350
MCL- |
(ugyi) ;
10OC
I
NA '
|
100 \p) ,
1
1
5
5
NOTES:
NA • Not Available
NO • No) Dotoctod
*MCL • USEPA Maximum Contaminant Lcvwl in drinking wal*r; (p) • propped.
"RAJ. • MinnvtoU R«comm«nd«d Allowable L*v«l In drinking wral*f.
Pag* 2 of 4
-------
TABLE 1
SUMMARY OF CONTAMINANT OCCURRENCE
OAK GROVE SANITARY LANDFILL RI
COMPOUND
•CMofOO«ru»n«
Acrcx«in
2-M«Uly1pn«no4
4~M«cnyipn«norf
B*»uo»e Acid
DuOiyi Ptim*i«t«
Bi*2-««Tiy«no<
8i««2-Chloro«,1y<) £iji*r
N-Nitro«odiph«oyl«min«
FREQUENCY OF DETECTION
GROUNO-
WATEfl
Si75
2/75
0/36
IfM
1/38
2/M
ana
1/M
Q/3fl
ana
SURFACE
WATER
0/19
a/16
a/7
1/7
1/7
a/7
a/7
a/7
0/7
0/7
SEDIMENT
oni
oni
1/12
*nz
an:
tnz
trt2
2AI2
1H2
2TI2
SOILS
0/21
0/71
NA
^ ,^-
NA
NA
NA
NA
NA
NA
NA
UAXJUUU
VALUE
DETECTED
8.1 ug/1
NO
NO
NO
13u?/1
ND
NO
NO
ND
NO
7>0 mo/kg
NA
OOugyl
44 UQ/I
13000 mo/Vg
NA
23.5 ug^
Mug/1
7200 mgAg
NA
24ug/1
NO
560 mgAg
NA
ZJug/l
NO
1300 mgAg
NA
41 ug/l
NO
2000 mgAg
NA
NO
NO
450 mgAg
NA
NO
NO
110 mgAg
NA
RAL"
(ug/T)
300
40
280
0.3
70
MCL-
(ug^)
\
NOTES.
NA • Not Av»il«Dl«
ND - Not 0«l*C1*d
*UCL • USEPA Utximum Contamirvcnt L«v»( In dnnking w«i«r (p) •
"RAL • Minn««ou R«comm«no«d AtlowcOl* L«v«4 in dnnkjng »«l«f
P>g« 3 o( 4
-------
TABLE 1
SUMMARY OF CONTAMINANT OCCURRENCE
OAK GROVE SANITARY LANDFILL Rl
COMPOUND
Di-f*-Ocry1 Pnmalaia
Chromium
Cooper
Lead
M»reury
Vanadium
Zinc
S«l»nium
Beryllium
FREQUENCY OF DETECTION
GROUND-
WATER
1/36
7/36
s/36
o/36
o/36
0/36
11/30
1/38
4/3e
SURFACE
WATER
0/7
7/7
0/7
2/7
1/7
1/7
5/7
0/7
0/7
SEDIMENT
0/12
11/12
«m
12/12
6/12
2/12
12/12
0/12
0/12
SOILS
NA
12/12
12/12
*,--•'"'
11/12
1/12
10/12
12/12
0/12
0/12
UAXJUUU
VALUE
DETECTED
13ug/l
NO
NO
NA
25 u^
72 uo/1
4BlflAfl
18 mgAg
e4ug/1
NO
10 mo/kg
244 mg/kg
NO
11 uo/1
6.1 mgAg
7.3 mg/Vg
NO
O^uo/l
0.02 mg/kg
0.02 mg/kg
NO
43ug/l
8.6 mg/kg
23 mgAg
47 ugfl
43ug/1
72 mg/kg
29 mgAg
fiug/l
NO
NO
NO
•.Suo/1
NO
NO
NO
RAL"
(Ufl/t)
120
1300
20
1.1
4f
MCf
(uo/T)
50
1300(p)
50
2
10
NOTES:
NA > Not Av«jl4bl«
NO -Not 0«t«ct*d
*MCL • USEPA Maximum Conuunirvant L*v»( In drinking wal*r. (p) • propo«ad.
"RAL • Uinn«tou R«comm«nd«d Allow«b<« L»v»t In drinking ««l«f.
Pig* 4 o( 4
-------
$ee Iboi/eixr
f JiK-rflnTlifiK?
lk'i(*blor (C)
IP-pi *'h lor f^poxidc 1C)
tK.-x*.-ltloroliOfueo« (C)
J iitdune (C)
rtcltiyJrrrf di lor ids (C)
far^rh ioo
.^.ninthrene
1'riVchlorJn.ifr* btphenyls (C)
I I . ? ?-l*tr*t Kvoi8o« (fj
\ 1 . 7 .'i letr> ' 'hylrne (C,
•-•; utif
umrs
uo/ 1
T;/*
uo/ 1
L^/l
lc«rf
hiph
tA/nn/ci
U(J/1
i»9/l
ui
Ufl/1
ug/l
ug/l
ug/l
"9/1
ug/l
UJ/1
uq/'l
un/l
ug/l
u^/ 1
ug/l
U5/I
U9/I
uii/ 1
uo/ 1
IM)/1
) t^/l
ug/l
CHRONIC
SIAMIARO
40
230
5.2
WO
.
.
i -
125
70
1.61
11
n. «
S.6
0.0069
213
5
1
155
12
0.89
0.029
114
558
5-9
0.00029
10
224
0.0*1
0.0017
190
O.«tt03li
2.1
30
0.15
0.016
68
4.S
0.00019
0.00046
0.00022
O.Ott
156 1
O.DP
2.1
0.0000^9
1)
6.9
Ii S\J\ I 1
AOfTE
STANDARD
-
I7ZO
45
10000
-
-
-
2145
720
110.4
32
53.9
?06
4.9
4132
40
8.7
341
81
2281
1.6
8974
5800
3500
?.4
Mb
4471
0.17
1.1
90100
2.5
1650
0.56
0.18
3717
3S6
0.52
0.5*
il.fl
1-tfOO
0.12
jr>
44^. p
2
??5)
657
t i i
ono
STAMDAAD
-
IOO(3B}
-
-
6.5 (2f)
8.5 (4A)
1000 (4A)
PAJtAJCTfft
{.l.2-IrtciilorDtittiyl«nc (C)
»myl chloride (C)
total
KITS
ug/l
ug/l
UQ/I
uy/l
u.j/1
CM ROM If
STANUAII>
2C3
120
2
7.6
166
AfttlE
SIAMCAF
5256
13976
203
2fll4
"•'•" Ivisod on <'i h.irilness of 1
one ii|)St ru.un ol>st.>rv;it ion
(C) c.'irc inoi;i-nii t hnnic:.il
mj;/l froiu
i r pi i nr
o.OOll
II. b
-------
TAIILE 3
SELECTED CrTEMlCAl-SFECIFIC POTENTIAL APPLICABLE OR RELEVAHT AWD APrROITUATE (vEdJIRrMKNTr, ./
PotanUal ARAR»
CNA Water Quality Criteria
for Protection of Oman H«allh
CWA Aofclant Water Quillty Criteria for
Prol»cllcwi of Aquatic LI f• c/
For Us* In S|>«<-1«1
Ci rcunat ap^ «s _
It-
It
*
c:
3
(/I
H
CD
CO
00
o
z
Acenapthene
Ac enaphthy lane
Ac role In
Acrylonltrlle
Aldrln
Anthracene
Antimony and Compound*
Axaenlc and Compound*
Araenic (V) and Caopound*
Areenlc (III) and Coopound*
Hater and PI ah Conjunct I <
Pi ah Irvftaatlon . Cbly
(08/1) (s»/l)
3 2x10-01 7.8x10-01
J.flxlO-OJ 6.1x10-0*
7.4x10-08 7.9x10-08
1.3x10-01 43
2.2x10-06 1.8x10-03
an Prearwater
Acuta/Chronlc
6.8ilO-02V2 1x10-02*
1 W2.6*
3.0x10-03
9.0/1.6
0.8*/4.8aclO-02>
0.3/O.J
Marine
Acuta/Chronlc SPWA/M~L (V)
(Oft/1) (o*/l) J/
0
3
5
1
2
6
9*/0 7«
0«10-01*
5ilO-02*
3ilO-03
3-/1. 3x10-02
9x10-02/3.6x10-02
*
4-
4-
Aabeatoa
Barlun and Cc«opounda
Bani(a)anthraean«
B«n<(c)acrldlD«
Banian*
Bantldlna
Ban«o(a)p7r«n«
B«n(o(b) fluorantban*
B«nto(ghi (perflari*
B*nso(k)fLooranthana
B«ryIlium «nd Coopounda
Rli(2-chloroatrn;l)athar
Rl«(2 rhlorolaoproprl )»t.h«r
» I ... I, I .-I ..n«(lir 1 l«lli«i
6.6x10-04
1.2x10-04
4.0x10-02
5.3x10-04
5.1*/0.?•
25*
6.8x10-06
1.2alO-04
0.1«/J.3x10-03*
-------
TABU-: }
STLKTH) CHEMICAL-SPECIFIC POTEXTIAL APPLICABLE CD RELEVAKT AHD AFFUnHUATE REOUIRtHKHTS
Pur U«« In S[)«cl»l
folantUI
4
*
4
C
a .
m
oo
Chaalcal HMM
CatxaltaB and Coopound*
Carbon TatrachLorlda
QilonJana
Chlorlnatad B«n*«n»*
ChlorlD«t»d M«ptitbkl«n««
Qiloroallyl Eth*r*
Chlorobvnt •>• (Mono)
Qi lorodl brOBOB«tho>«
Chloroform
2-Chloropti«nol
Oiromlim III «nd Couponed*
Oircmim VI Bid Compound!
Coppar and CooipoxKid*
Cr«nld»«
DOT
01 butyl Fhthalct*
Dlcblorob«n«o**
1 . 2-DlchLorob«ru«Q»
1. 3-DlchLorob«ni«t>«
1 . »-Dlchlorob«n««i«
3.3' -Dlchlorob«ntldln«
1 . 2 Dlchloro«th«n» (EDC)
1>I chloro«Uijl»n»«
CM* H*t«r Quality Criteria
for Frot«otloti of IKiun Baaltb
H«t«r and f0-0)
4.4ilO-0; 4.8x10-07
l.t.10-0* l.talO-02
170 3431
3.0x10-02
2x10-01
2.4x10-06 2.4xlO-OS
3) 134
4x10-01 2.4
1x10-04 2*10-05
9.4x10-04 2 4x10-01
3.1ilO-0) l.»ilO-01
CHA Ajrf>l«nt Watar Quality
Protactloo of Aquatl
Praabvatar
Aovita/Chronlo
(•*/!)
l.»i!0-03»/l. U10-03*
J.i«10»01
2.4x10-03/4.3x10-04
2. JxlO-01«/J. 0x10-02*
!.»•
2.3x10^02*
a.axiotoivi.2*
4.3V2.0*
1.7V0.2+
1 4x10-02/1.1x10-02
1.8xlO-02»/l.ZxlO-02«
2. 2-X10-02/J. 2x10-03
1.1x10-01/1.0x10-04
1.W7. 6x10-01*
l.lxlO»02«/2 OxlO*Ol«
l.lxlOiOl*
Criteria fur
c Llfa c/
Harlna
Acuta/CKrunlc SlMA/M:i. Goal
(««/l> (««/!) ii/
4 3x10-02/9.1x10-02
5 0«10»01 0
9. OxlO-OJ/4. 0x10-06
1 4»10-01*/1 2x10-01*
7 lilO-03«
1 0x10*01
1. I/). 0x10-02
2.9x10-03/2.9x10-03
1.0x10-03/1.0x10-01
1 3x10-04/1.0x10-06
1 9«
7.5x10-01
1 lx!0«02« 0
2 2t02«
I
-------
TABI.K 3
SELECTED CHEMICAL-SPEC me PtrmrriAi. AFTLICAHLI CB RELEVANT AJTD APranniiATE REQUIREMENTS •/
Pot«ntt«l ARAIU b/
For U«» In S|»cl«l
Cj rctyoj^ aaicta
CM* H«t«r Quality Criteria
for frot*ctlOD of BIXMO B«*lth
CMA A^>l«ot W«t«r Quality Crlt.rl. for
Protection of Aquatic Life c/
*
*
*
£
9
C/l
H
vO
00
00
o
*
*
4
Mat»r •>
fl«h In***
<•»/!>
Pith Ccanaxpt-lc
Only
(••/I)
Ti ««l»i«l «i
Acut«A3iranlc
(•m/i)
Harln*
Acut*/Chrcnlc
«nol
3.4 - Dl chlorop*>«nol
2,3-Dlchlonrpti«Dol
2.4-Dlchljoroptnoaiyac.tlc Acid (2.4-D)
1.3-Dlchtorouiup«mi«
Dlaldrln
Dl«thylptiUMUt«
Bli(2-«Lhylh«yl)ptiUt«Ut* (DEBT)
Dl cUby Inl troiadn*
7.1
2 , * -Dl«*tb7lpti«ool
* . 4-Dinl tro-o-cr*«ol
2.»-Dlnltro|)ti«ool
1 . 2-D1 p*i«Btylhriin-OV2 3ilO-Oh
4 3ilO 01*
4 OilO 02V1 6ilO-02«
;. OilO 0.1
7 DilO-03
I'ny.o 3 of 7
-------
TAHI.K 3
CHEMICAL -SPECIFIC POTEHTIAL APPLICABLE CH RELCVANT AND APIVOFRIATE
Ti a,/
APA«« b/
*
*
*
AUGUST
CD
>— •
vO
CD
CD
o
3
*
*
*
.
Chemical Hesx
Beptecblot
Baiachlorobetiiene
Hai ace loro butadiene
leoma-BDCH (Undue)
Technical-Boca
Beiechlort>cyclopentadle«e
loll.!^!^"1'
laophorone
LeeJ end Coxqpound* (Inorganic)
Mercury and Coe^xjunda (ALkyl)
Heicury end Campouadt (loortetilo)
MeLhorychlor
Methyl Chloride
2-Methyl-4-chloroc*Mool
CHA Water Quality Criteria
for Protection of Biaun Bealth
Water end Plih Conauc^>tloa
flab loteatlon Oily
(««/l) («,/!)
2.8x10-07 2.TI10-07
7.2x10-07 7.4x10-07
4.3x10-04 3x10-02
• .2x10-06 3.1x10-0)
1.2x10-0) 4.1x10-0)
2.1x10-01
l.*x!0-03 6.74x10-03
3x10-02
1.4x10-04 1.3x10-04
1x10-01
CMA Aofcleot Water Quality
Protection of Aquatic
Preahoater
Acute/Chrunlc
(«*/!)
3.2x10-04/3.8x10-06
•.0x10-02/9. 3x10-03*
7. OxlO-03*/). 2x10-03*
9. BxlO-01*/). 4x10-01*
1.17x10*02*
6.0x10-02/3.2x10-03*
2.4x10-03/1.2x10-0)
1.4x10-03/1.2x10-0)
0.3x10-04*
Criteria fur
Ufa c/
hUclna
Acula/air..ilc SIMA/MIL Goal
(««/l) (=»/!) d/
).3slO-0)/3.6ilO-06
3 2ilO-02«
7.0x10-03*
9.4x10-01*
1.2x10*01*
0.1/3.6x10-03
2.14x10-03/2.3x10-03
2.1x10-03/2.3x10-03
0.3UO-04*
I-6-ohloropbeool
3 - Muooch Lo roptt eno 1
4-HoooohLoroptieDoL
Mlckel «nd CceqiouvcU
Nitrate (•• H)
HI trobeniene
HI trophenol*
1. 3x10-10
10
20
txlO-01
!.«»/!.4x10-01*
2.7x10*01*
2.3xlO-01*/l.SxlO-01*
7.3x10-02/8.3x10-03
6.6
4.8*
f 7
-------
TAMI
SELECTED CHDflCAL-SPECIFIC POTEHTIAL APFLICABLE CR RELEVANT AITD APPROPRIATE R^QUIRmENTS •/
Fci U.« In Special
Potential AKARa b/
CHA Hater Quality
Criteria
for Protection of BiaMD Bealtb
*
*
*
AUGUST 8,
£
GO
CD
O
*
*
*
Oia»lcal »aaM>
Ultra* eailnee)
D-mtroeodlphanylaaUne
II - •) 1 tr oe opyr ro 1 1 dl na
Par* Olchorobenxena
PanLachlorlnated Ethane*
Pent ec h loropheno 1
Rianol
Pbtbalata Eatera
PolychLorloataxI Blphenyl* (PCBa)
Bedlonuclldee. Oroaa alpha activity
Badlua 226 end 228
SelaoJua) and Coxqxnxoda
Silver and Coxepouoda
2.3.7,8-TO» (Oioxlo)
Tetrachlorioatad Etbanea
1 . 2, 4 . 3-Tatr achlorobanicne
1, 1,2.2-Tetxachloroethana
TetrecrUoroathanea
Te tr ac hi oroa Uiy 1 an a
2. 3. 4. 6-Tatrachlorophanol
Thai Ilia and Conpotanda
Hater and
Plah Io(eatloa
(a«/l)
4.9x10-03
1.6x10-03
7.4x10-02
1
3.3
7.9x10-08
1.0x10-02
3.0x10-02
3.8x10-02
1.7x10-04
8x10-04
1.3x10-02
Pith Con*ixti>tion
Cxi IT
(«W/l)
1.6x10-02
9.2x10-02
8.3x10-02
7.9x10-08
13 pCl/1
3 pCl/1
1.0x10-02
3.0x10-02
8 pCl/1
4.8x10-02
1.1x10-02
8.9x10-03
4.8x10-02
CVU An*> lent Miter Quality Criteria for
Protection of Aquatic Life c/
Prethvatat Marine
Acute/Chronic Acute/Chronic SPHA/MM. Goal
<«*/!> (o*/l> (a.8/1) d/
3.8* 3.3il«H03*
7.2*/l.l* 3 9xlO-01*/2. 8x10-01*
2.0x10-02/1.3x10-02 1.3x10-02/7.9x10-03
1.0x10*01/2.3 58
9. 4xlO-01*/3. 0x10-03* 2 . 9*/3. 4x 10-03*
2. 0x10-03/1. 4ilO-03 1.0x10-02/3,0x10-03
2.6x10-01/3.3x10-02 4. 1x10-01/3.4x10-02
4. U10-03*/!. 2x10-04 2.3x10-03
<1. Ox 10-03*/< 1.0x10-08
9.3*
2.4* 9.0*
9.3*
3. 2*/8. 4x10-01* 1.0xl&*01*/4. 3x10-01*
4.4x10-01
1.4V4. 0x10-02* 2 1x10-03*
PHRO 5 of 7
-------
TAIUJ-: 3
SElJtCTTD CHEMICAL-SPECIFIC POTDTTIAL APPLICABLE OR RZLEVAJTr AMD APPROPRIATE RtOUlHttlOiTb «/
For Uae In Si>*cl>l
b/
CWA Hater Quality Criteria
for Protection of HiMn Health
CWA Aafclent Water Quality Crlt.il. fur
Protection of Aquatic Life c/
Trlchlorcoonofluor
2,«.J Trlchloropbeool 2.«
2.4.»-Trlchlorophenol 1.2x10-0)
2, «, J-TrlchloroTifrenrujpauploolo Aold
TrlhaloxMthanea (Total) b
Tritium
Vinyl Chloride 2x10-0)
Zlno and Caapotxoda
3.1x10-0)
S. 3x10-01
». 7x10-01*
Chemical Hane
Toluene
Toxaphene
Trlbroooae thane (Brne»ifor»)
Tr Ichlor lotted Ethenea
1.1. 1-Trlchloroethaoe
1. 1.2-Trlchloroethana
Tr Ichloroethylene
Water and
Plah Infection
14
7.1x10-07
4x10-04
2.7x10-0)
Flah CooauBplloo
Ctaly
420
7.3x10-07
1000
4.2x10-02
• .1x10-02
Freebvater
Acu te /Ctit on 1 o
1.7x10*01*
7.3x10-04/2.0x10-07
t.4«
4.1xlO«01«/2. lx!0«01*
Harln*
Acute/QiruUc S[MA/>CL Goal
4.3*/1.0*
2. U10 0*/ZllO-0/
3.1x10*01* 2.0x10-01
2.0* 0
1.3x10-01/1.1x10-01 *.exlO-02/a.(xlO-02
a/ Additional cheaUoal-cpeclflo re^lreatent^ Mill b« added laDt Ale Quality Criteria) after aoalyal* of additional atatutei.
t/ Mien Uro or avra vmLue* oootllot. the lomrnx value |enexally abould be oaed.
t/ Federal water quality criteria (rMQC) are Dot le««lL7 aaforoeabU •teadarda. but are potentially relevant and appropriate to CZBCLA actloaa. CZBCLA
lUKdHZXBHI) requlrea conalderatlon of four factor* «*en determlalni «4v.thar FWQC axe relevant and appropriate: 1) the dealinatled or potential uae of the
• urf«ce or iroxndvater. 2) the envlronnantal atedla affected. 3) the purpoeea for Mhlch auch criteria were developed. ai>d *) the lateat Infonnatlon available.
-------
TAIM.K 3
d/ For »at»r thet la to be need for drinking, the KTLe eet under the SWA ere generally the applicable or relevent end appropriate alanclard A «iai,,ianl fm
drlrUIng water o»r» •trln«ant then «n hCL ouy b« n*»d*d In >p«cl*l c IrcutnaLanc ••. tuch a* "t>»r» nulllpl* canL»mlnanL» In ground «nLer or anjlLlplt poUi«nyo .if
•rpotur* pr««»nl »rt.r«ordln«ry rl*k(. In ••ttlng • l»v»l mor« (Lrlngtnt then Lh* rCL In *uch c«i»«, • > I t«-|p*c 1 f Ic determination •lion Id he mede by
considering MCLG». the Agency'e policy on the uee of eppropriele rl«k ren«ee for cerclnogene (10-4 to 10-7 Individual lifetime risk), leveln of qiiaiiti fleet lm:
end other pertinent guideline*. Prior coniultetlon with Beedquertere 1* encouraged In euch c«»ei
• Low««t Obeerved Effect Level.
» Herdneei dependent crlterle (100 •»/! ueed); refer to epeclflc criteria document* for equetione to calculate criteria hojad on oUiar water hardnaae valuaa
Sourcee: U.S. EPA. Superfund fubllc Health t^eluetlon Manuel. EPA 3«0/J-fl6/060 (OSWER Directive 9285.4-1) October 1986 end U.S. EPA. Quality Criteria for
Water 1984. EPA 440/3-84-001. htay 1986 ;,- 7 of 7
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Responsiveness Summary
for the
Oak Grove Sanitary Landfill Superfund Site
Oak Grove Township, Anoka County, Minnesota
This community responsiveness summary has been developed to document community
involvement and concerns during the Remedial Investigation/Feasibility Study and
proposed plan phases of the Oak Grove Sanitary Landfill Superfund Site process and to
respond to comments received during the public comment period. Also included as an
attachment is a summary of the community relations activities conducted by the Minnesota
Pollution Control Agency (MPCA) during the Superfund project at the Oak Grove Sanitary
Landfill Site.
OVERVIEW
Based on the findings of the remedial investigation and feasibility study, the U.S.
Environmental Protection Agency (U.S. EPA) and the MPCA recommended long-term
monitoring of the shallow aquifer, deep (Valley Train) aquifer, surface water and sediments
at the Oak Grove Sanitary Landfill. This proposed plan, designed to address ground water
contamination at Oak Grove Sanitary Landfill, received conditional approval from the
majority of those who commented during the public meeting, initial 30-day comment
period, and 15-day extension of the comment period.
The proposed plan was acceptable to most local residents if:
The U.S. EPA and the MPCA perform additional testing on the wetlands adjoining
the landfill to find out how the wetland may act as a biological treatment system for
some of the chemicals found in the ground water, to determine the possible effects
of contamination on the wetland and its inhabitants; and to find out more about the
surface water movement in the wetland.
The U.S. EPA and MPCA install a system to pump and treat the contaminated
ground water if it affects the Valley Train aquifer used by the surrounding
community for drinking water.
The cap proposed for controlling Jie source of the contamination works effectively
in combination with long-term monitoring of the landfill.
Several individuals commenting during the public meeting held October 24, 1990 preferred
immediate installation of a pump-and-treat system for ground water remediation.
Generally, however, members of the public were willing to wait and see if the combined
capping and monitoring remedies and the biological treatment provided by the wetland are
sufficient to prevent public health and environmental impacts associated with the landfill.
The majority of comments forcefully opposed the use of land adjoining the Oak Grove
Sanitary LandfiD (called "Site D" by Anoka County and the Metropolitan Council, the
responsible governmental units) as the location of a new landfill. Residents cited the Oak
Grove Sanitary Landfill's contamination problems and the delays and expense of
remediation as reasons for their opposition to use of Site D for a new facility. This
strongly felt local issue dominated much of the public discussion on the proposed plan.
-------
BACKGROUND ON COMMUNITY INVOLVEMENT
A high level of community interest in the Oak Grove site has existed during the time the
landfill was operating and continued during the closure of the landfill and throughout the
Superfund project. The site is in a residential area, with no surrounding businesses
affected by the Superfund process or activities. The primary focus of residents' concerns
is ground water contamination and its potential effect on nearby residential wells. The
community seems most concerned with potential health effects and environmental quality,
although a few people had concerns about residential property values.
Other concerns have arisen more recently about the site and its potential impacts. Anoka
County and the Metropolitan Council have undertaken a process to locate a site for a new
landfill, and one prospective site, Site D, is a property adjoining the Oak Grove site. The
property is owned by the current owners and former operators of the Oak Grove landfill.
These circumstances have fccussed attention on the Oak Grove site and its ground water
contamination problems.
Stronger general environmental concerns (about potential impacts on the wetlands, Cedar
Creek and the Rum River) may be attributable to several factors including new residential
development in the Andover/ Northern Anoka County area; activity by a new environmental
group, the Rum River Conservation Coalition; increased environmental education in the
schools; activity at other state and federal Superfund sites in the area; and increased
environmental awareness resulting from Earth Day 1990.
The MPCA has served as the lead agency on community relations activities. In November
1985, residents were provided with information on plans for the project through a news
release, fact sheet and public meeting. A second public meeting was held and fact sheet
provided in December 1986, following approval of the work plan and start of field work.
Letters to update interested persons on the progress of the ground water investigation were
mailed to those on the mailing list in February and June 1988. These letters also included
information on the MPCA's decision to conduct a source control feasibility study and the
purpose of the study. A public meeting on the source control operable unit was held
September 14,1988 halfway through the public comment period of September 2 - 23,
1988. Fact sheets were distributed at the meeting and made available at the township hall.
Information on the proposed plan for the ground water operable unit was provided through
an October 11,1990 news release sent to all local and metropolitan media outlets, a fact
sheet describing the proposed plan sent to the current mailing list, a display ad in the
Anoka County Union, and phone calls to several residents and local officials who had
expressed interest in landfill activities. In addition, local residents hand-delivered flyers in
the neighborhood surrounding the landfill.
SUMMARY OF PUBLIC COMMENTS AND LEAD AGENCY RESPONSE
Investigation of the Site
1. Comment: Not enough investigation has been done of surface water
in Cedar Creek.
During the Remedial Investigation, monitoring wells were installed around the landfill to
help the MPCA and the U.S. EPA to define the "plume" or extent of the contamination.
Two areas in the wetland, where the ground water discharges, were also sampled. Results
from these investigations support the MPCA's and U.S. EPA's belief that the contaminants
have not affected Cedar Creek. However, the MPCA and the U.S. EPA plan further
-------
sampling of surface water and sediments in the wetland. These results should provide the
two agencies with more information about potential impacts on Cedar Creek.
2. Comment: Not enough investigation has been done of reports of
barrels being dumped into the landfill. The MPCA/U.S. EPA should dig
into the landfill to locate any barrels buried there.
The MPCA and the U.S. EPA have reviewed large numbers of records about and slides of
the Oak Grove Sanitary Landfill. Although the two agencies believe industrial wastes were
disposed of at the site, they do not believe drummed wastes remain at the landfill. In
addition, testing on the surface of the landfill at 100 foot intervals revealed no "hot spots,"
or high levels of organic vapors. These "hot spots" indicate more hazardous or drummed
wastes.
There are several reasons why the MPCA and U.S. EPA do not dig into the landfill or plan
to remove any of the wastes buried there. The landfill's contents cannot be removed to
another location because transferring wastes does not reduce their toxiciry, mobility or
volume and increases the risk of public exposure to the wastes. Drilling holes into the
landfill wastes may pose an explosion hazard if sparks from the drilling equipment ignite
methane gases. The safest way to handle the wastes is to contain them by capping and to
provide a venting system for methane gases.
3. Comment: Insufficient investigation has been done of possible
impacts of the landfill on wildlife in the area.
The MPCA and the U.S. EPA plan further sampling of surface water and sediments in the
wetlands. This should give the two agencies a better idea about what contaminants from
the landfill may be affecting area wildlife.
4 . Comment: The MPCA/U.S. EPA should investigate seepage
(leachate) coming from the sides of the landfill.
The seepage from the landfill's sides (called leachate) results from the wastes being
inadequately covered and the landfill possibly being improperly sloped to provide good
drainage of rainwater and snowmelt The landfill cap will solve this leachate problem.
5. Comment: There is not enough information about what is happening
in the wetland and how chemicals are being "treated" there.
The MPCA and the U.S. EPA need more information about the wetland md how natural
treatment of contaminants is taking place. The two agencies will perform inore surface
water and sediment tests to gather additional information about the wetland.
6. Comment: The extent of the surface water contamination in the
wetland may not be the same as the extent of the ground water
contamination. More work needs to be done to determine the flow of
chemicals in the surface water.
The MPCA and the U.S. EPA agree with this comment. The two agencies will perform
more surface water and sediment testing in the wetland to gather more information about
the surface water.
7. Comment: Low levels of volatile organic compounds (VOCs) were
detected in wells upgradient (upstream in the ground water flow) from the
-------
landfill. The MPCA and the U.S. EPA should investigate the source of
these VOCs.
The levels of VOCs found in the upgradient wells were very low compared with the
Minnesota Department of Health's Recommended Allowable Limits. Given this fact, the
MPCA and U.S. EPA believe that continued monitoring of these wells seems most
appropriate. If VOC levels increase in these upgradient wells, the MPCA would have to
investigate further, but this investigation would not involve the Oak Grove Sanitary
Landfill.
8 . Comment: The MPCA and the U.S. EPA should make sure that no
residents in the area are using the shallow aquifer for drinking water.
The MPCA and U.S. EPA have discovered no shallow drinking water
wells in the area and do not believe that the shallow aquifer is
a drinking water source. Additionally, institutional controls
which are part of the selected remedy will prohibit any wells
from being located in the shallow aquifer.
9. Comment: Analyses of 1982 - 1983 water samples from a monitoring
well in the wetland near the southern boundary of the landfill showed very
high VOC levels. The MPCA should explain why VOC levels from 1986 -
1990 (taken from newer monitoring wells) are so much lower and why
older monitoring wells are not still sampled.
The original high concentration of VOCs may have arisen from active seeps that flushed
through the wetland system and volatilized (went up in the air). The MPCA and the U.S.
EPA feel that the 1986 -1990 tests reflect the current situation at the landfill, and it is this
data the two agencies arc using to make decisions about the site. However, wetland
investigation will continue. The old monitoring wells are not considered reliable and will
be abandoned by the MPCA and U.S. EPA.
10. Comment: The Water Quality Division of the MPCA has suggested
that further information be gathered on surface water quality and impacts of
contamination. This should be done.
The MPCA and the U.S. EPA agree and will obtain additional data about the surface water
11. Comment: The Feasibility Study said that the technical feasibility of
a ground water pump-and-treatment system would be "questionable' when
it would only present some technical difficulties. It also said that the
community's acceptance of a ground water pump out system would be
"unknown" when it is likely that it would be acceptable to the commun:ty.
The MPCA and the U.S. EPA agree with these comments, however, this does not affect
the MPCA's or U.S. EPA's preferred remedy. The pump-and-treat system would drain
the wetland and be costly to implement, but its main drawback is that this environmental
degradation and cost may not be necessary to address the contamination problems. The
two agencies believe the most prudent choice is to monitor long-term to see if natural
processes continue to work on the contaminants.
12. Comment: The landfill cap should have a leachate collection system
to collect leachate at the toe of the landfill.
-------
The Landfill cap should reduce or eliminate the production of leachaie. The MPCA and
U.S. EPA believe that a leachate collection system will not be needed if the design and the
construction of the cap arc properly completed.
13. Comment: A drain tile should be considered instead of a pumping
system along the south boundary of the wetland. This would minimize
water removal from the wetland.
If the additional work on surface water and the wetlands or the long-term monitoring
indicate that a ground water collection and treatment system is needed, this alternative will
be considered along with many others.
14. Comment: There is no certainty that the ground water remedy and
the cap will actually reduce or eliminate contaminated ground water.
The long-term monitoring plan proposed by the MPCA and the U.S. EPA will help the two
agencies determine how successful the cap is in reducing ground water contamination. If
the remedy does not reduce or eliminate ground water contamination, the MPCA and the
U.S. EPA will re-open the site for further action, such as a pump-and-treat system for
ground water. Federal Superfund sites where hazardous substances, pollutants, or
contaminants are left in place are re-evaluated every five years, so that reviews of the
remedy's effectiveness will take place long into the future.
15. Comment: It is not clear from the Remedial Investigation and
Feasibility Study reports that shallow and deep ground water does
discharge to the wetland.
Shallow ground water does discharge to the surface water in the wetland, according to all
the data collected by the MPCA and the U.S. EPA. Ground water contained within the
lower portion of the deep aquifer does not discharge to the wetland, but also does not
contain contaminants at any level of concern.
16. Comment: There is no proof that there is a restraining layer between
the aquifers that will prevent contamination of the deep (drinking water)
aquifer.
Hydraulic conductivity is a measurement of how easily water can move through a material.
The hydraulic conductivity of the restraining layer is lower than the overlying sand or
underlying sand. This indicates that groun-i water has difficulty moving from the overlying
sand through the till and into the underlying sand. Additionally, sample results indicate that
contaminants found in the shallow aquifer are not present in the lower aquifer. This
indicates the presence of a physical barrier between the two aquifer systems. In addition to
the physical barrier, a hydraulic barrier in the form of an upward movement of ground
water from the lower aquifer to the upper aquifer protects the lower aquifer from
contamination.
17. Comment: Increasing development in the community may lead to
increased drawdown in the lower aquifer. This may change the ground
water dynamics (the flow from lower to upper aquifer) and begin to draw
water from the more contaminated shallow aquifer downward.
The long-term monitoring proposed will be able to determine if water movement changes at
the site in response to development. If future test results indicate any increase in the
-------
contaminant levels in the lower aquifer, both the MPCA and the U.S. EPA can change the
remedy and install a system to treat the ground water.
18. Comment: There may be negative environmental effects from heat
production in the landfill as the garbage degrades.
The MPCA and the U.S. EPA do not believe that heat from the degradation of the landfill
wastes will have any adverse environmental impacts.
Remedy Preference
19. Comment: A pump-and-treat system with reinjection of treated
ground water is the best remedy for the ground water contamination.
A system for pumping and treating the contaminated ground water would be significantly
more expensive than a long-term monitoring program, may not provide more protection for
the public and the environment, and may adversely affect the wetland, Reinjection of
treated ground water is not currently permitted under Minnesota law except in special cases.
In one of these cases, ground water is being reinjected into a calcareous fen (a rare and
unique natural environment) to preserve it, with only limited success. It is the MPCA's
and U.S. EPA's belief that a pump-and-treat system should only be used if the capping
system is not effective in reducing or eliminating ground water contamination.
20. Comment: A pump-and-treat system is-the best remedy for the
ground water contamination.
Sec response above.
MPCA/U.S. EPA Process and Public Information Efforts
21. Comment: The community is concerned about who is going to
monitor the work done at the landfill to make sure it is done properly. This
is especially an issue if potentially responsible parties take over the cleanup
process.
Technical teams from the MPCA and the U.S. EPA must review and approve all work
plans, reports, and engineering plans for the Oak Grove Sanitary Landfill. These technical
teams include the project manager, hydrogeologist, and engineer familiar with landfills.
The MPCA and/or the U.S. EPA oversee consultants employed by the agencies or the
potentially responsible parties in exactly the same way. Through this oversight process,
both the MPCA and U.S. EPA can assure that the cleanup meets all state and federal
standards and accomplishes the cleanup goals.
22. Comment: There have been many delays in addressing the landfill's
problems, and these delays have made the situation and the risk to the
community worse.
Superfund investigation and cleanup activities are complex and time-consuming, and there
have been delays in completing the investigations to date. Among the delays that have
slowed completion of the project are: greater review times for documents because two
levels of review are involved; staff changes at both the MPCA and the U.S. EPA; changing
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consultants at one point in the investigation; and inability to gain site access on two
occasions.
However, the average length of tune from the beginning of the Remedial Investigation to
the completion of Remedial Action is 5 1/2 to 6 1/2 years for federal Superfund sites. The
Remedial Investigation at Oak Grove1 Sanitary Landfill began in 1985, so the length of time
to complete the work is not unusual for Superfund sites. The MPCA and U.S. EPA do not
believe this delay has increased any health or environmental risk to the community.
23. Comment: The MPCA/U.S. EPA have not provided enough public
information about the chemicals found in the ground water or their potential
health effects.
The fact sheet on the site mailed to residents on October 11 and available at the public
meeting contained brief overviews of health risk information. The Remedial Investigation
and Feasibility Report available at the Oak Grove Township Hall and the public library
contained additional data. However, the MPCA and the U.S. EPA did not feel that these
two resources provided enough information to residents. A fact sheet, prepared by the
MPCA and the Minnesota Department of Health, addressed health issues more specifically.
This fact sheet was sent to interested parties and responsible parties on November 15,1990
along with notice of extension of the public comment period,
24. Comment: Not enough general information has been given to
residents, and many affected people did not know about the public meeting.
The MPCA and U.S. EPA provided notice of the public meeting in a variety of ways,
including: a display ad in the Anoka County Union; a news release (used to prepare a
large article about the site and the proposed meeting in the Anoka County Union) to
newspapers and radio stations in the area; a mailing of the fact sheet to all interested parties
who attended the previous public meeting in 1988; and calls to specific officials interested
in the site. Residents also received nonce from the Oak Grove Townshi- Board, and
several residents delivered flyers to households. The MPCA and the U EPA will
improve the accuracy of the current mailing list for future public notice.
25. Comment: The efforts of Oak Grove Township to get information to
the residents was greatly appreciated.
The MPCA and the U.S. EPA also appreciate the assistance of the Oak Grove Township
Board in getting information to residents.
26. Comment: The public meeting should have been held in the Oak
Grove Township Hall.
Three factors prevented the MPCA and U.S. EPA from using the Oak Grove Township
Hall for the public meeting: the hall was too small for the number of people expected to
attend the meeting; the previous MPCA information officer assigned to the site
recommended that the meeting be held in a different location; and the meeting moderator
suggested t^r Andover Community School. The MPCA and U.S. EPA will make sure that
future meetings are located as close to the site as possible.
27. Comment: The public comment period should be placed at the end of
a public meeting, after the question-and-answer session.
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In any future meetings, the MPCA and the U.S. EPA will place the formal comment period
at the end of the meeting, after the question-and-answer period.
28. Comment: Anoka County staff were not sufficiently informed about
the public meeting or about the Remedial Investigation/Feasibility Study
results.
Ajioka County has received notices and investigation reports about the site throughout the
history of the project Anoka County's Solid Waste Officer received notice of the proposed
plan meeting, but did not receive a copy of the proposed plan or the final Remedial
Investigation/Feasibility Study reports. These reports were sent to the Anoka County Solid
Waste Officer, and, at his request, the public comment period was extended to allow
sufficient time for Anoka County's review and comments.
Liability Issues
29. Comment: The potentially responsible parties should pay 100
percent of the costs of investigation and cleanup.
Both the state and federal Superfund programs are based on a "polluter pays" philosophy.
The federal Superfund program has covered the costs of investigation and cleanup to date,
but these costs will be recovered later from potentially responsible parties. The U.S.
EPA, working with the U.S. Department of Justice, has been identifying additional
generators of industrial wastes disposed of at the Oak Grove Sanitary Landfill. Some of
these generators have expressed a willingness to cooperate with the two agencies and to
assume cleanup responsibilities.
30. Comment: The community is concerned about who will pay for
future problems if the remedy doesn't work.
The potentially responsible parties who have been identified or who will be identified in the
future are liable for all the cleanup costs at the site that result from their activities. If the
proposed cap and ground water monitoring do not remedy the problem, the MPCA and the
U.S. EPA can always go back to the potentially responsible parties to do more work.
31. Comment: The community is unsure about whether the MPCA or
U.S. EPA will be able to recover costs from potentially responsible parties.
Both the MPCA and the U.S. EPA will attempt to recover costs from potentially
responsible parties, and both agencies have about 75 - 80 percent success rate in recovering
costs from potentially responsible parties.
Health Issues
31. Comment: One community member living near the site believed that
her spouse's esophageal cancer might be attributable to contaminants on the
site.
It is very difficult to determine what causes cancer, especially since so many lifestyle
factors (such as smoking and occupational exposure to chemicals) have been implicated in
cancer cases. Health risk assessments performed at Superfund sites, however, have
commonly looked at how the chemicals reach the person (pathways), how much of the
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chemical the person is exposed to, how long the exposure has been, and how carcinogenic
the chemical is.
Residents living near the Oak Grove Sanitary Landfill can be affected by the chemicals only
through ground water and surface water. The primary pathway of exposure would be
through drinking contaminated water. Repeated testing of water samples from residential
wells in the area has shown no chemicals in levels above the Minnesota Department of
Health's Recommended Allowable Limits for drinking water, and in most cases no
detectable chemicals. Therefore, it is extremely unlikely that the contaminants detected in
the landfill have made their way to residents or have caused cancer.
32. Comment: Insufficient residential well testing has been done near
the site.
Results of numerous tests on shallow and deep ground water have indicated that no
contamination is migrating off-site to nearby residential wells. Deep aquifer wells installed
200 feet downgradicnt from the edge of the landfill do not show any signs of ground water
contamination. There has been sampling conducted at a number of residences near the
landfill, none of which showed contamination.
33. Comment: Residents are concerned about children playing in Cedar
Creek.
The results of surface water testing conducted during the Remedial Investigation do not
show any surface water contamination that would be expected to migrate to Cedar Creek.
It is the MPCA's and U.S. EPA's belief that there are no contaminants migrating from the
landfill to Cedar Creek.
34. Comment: The site should be fenced to protect children and
household pets from coming in contact with the landfill.
Because the landfill is located in a sparsely populated area and is mostly covered in lime
sludge, the MPCA and the U.S. EPA have not believed that fencing the site is necessary.
The site will be fenced after the landfill cap is completed, primarily to protect the integrity
of the cap.
Capping Issues
35. Comment: Capping systems have not been very successful in
preventing methane gas buildup.
Some capping systems are not designed to capture and direct methane gas and, as a result,
vnethane gas buildup can be a problem. The capping system selected for the Oak Grove
Sanitary Landfill, however, is designed with a layer which captures and directs methane
gas so that buildup won't occur.
36. Comment: The community is concerned that the weight of the cap
will press wastes out of the landfill.
When the cap was designed, factors such as the final weight of the cap and the equipment
used to install'the cap were considered. These factors, alor.; with the type and quantity of
wastes present at the landfill, were evaluated so that a cover :ould be designed which bes:
keeps waste materials in place.
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37. Comment: The community wants to know if landfill cover and
monitoring systems have been successfully used at other sites.
Landfill coven, combined with ground water monitoring systems, exist at several sites in
Minnesota and have been found to successfully reduce ground water contamination
resulting from landfill wastes.
38. Comment: The residents are concerned about the possibility of
methane gas buildup in the landfill.
See answer to Comment #35.
Site D. Future Landfill Siting
37. Comment: The residents in the area are opposed to siting a new
landfill near the Oak Grove Sanitary Landfill. (Majority of residents at the public
meeting)
Neither the MPCA or the U.S. EPA is the responsible governmental unit deciding on the
possible siting of a new landfill in Anoka County. Anoka County officials have been
provided information about the Oak Grove Sanitary Landfill investigation. A copy of the
public meeting transcript will be provided to Anoka County officials and will be available at
the information repository at the Oak Grove Township Hall.
Potentially Responsible Party Comments
38. Comment: The MPCA and U.S. EPA are failing to work with
potentially responsible parties interested in cleaning up the site.
The MPCA has had a long history of attempting to work with the owners and former
operators of the Oak Grove Sanitary Landfill, both before the closing of the facility and
afterward. Among the landmarks in the MPCA's enforcement history are:
August 1971, Joseph Egan received a permit to operate the landfill.
May 1976, the MPCA Citizens Board voted unanimously to revoke the permit.
The decision was stayed in District Court in September 1976.
In October 1977, the Board approved a stipulation agreeement between Anoka
County, the MPCA, Northwest Disposal Inc. and Joseph Egan which gave consent by the
County and the potentially responsible parties to revocation of the permit.
" The landfill closed in December 1983.
North .vest Disposal ceased ground water monitoring at the landfill in January 1984.
Both Northwcit Disposal and Joseph Egan were requested to continue monitoring by the
MPCA, but neither party responded.
In August 1984, the MPCA Citizens Board issued a Request for Response Action
(a RFRA or enforcement order) to Joseph Egan, Northwest Disposal, and the Egan Family
Trust This gave the potentially responsible parties named the opportunity to indicate
willingness to negotiate a Consent Order, or binding legal agreement, until September 11,
1984 and to negotiate with the MPCA until November 10,1984. Although negotiations
took place, there was no agreement.
In November 1984, the MPCA Board issued a Determination of Inadequate
Reponse for the Oak Grove Sanitary Landfill. This determination allowed the MPCA to
negotiate an agreement with the U.S. EPA to use federal Supcrfund money on the site.
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No funds have been spent by the potentially responsible parties on the Remedial
Investigations or Feasibility Studies conducted so far. Recently, a group of generators
who are also considered potentially responsible parties have formed a steering committee to
work with the iMPCA and the U.S. EPA. Discussions have taken place between U.S. EPA
and this steering committee. A consulting firm representing this group of potentially
responsible parties has commented, for the most part favorably, on the MPCA's and U.S.
EPA's proposed remedy for ground water at the site.
39. Comment: The MPCA and U.S. EPA are implying that tax dollars
are being used to clean up the site.
The fact sheets and news releases prepared by the MPCA and the U.S. EPA have
mentioned that federal Supcrfund dollars are being used to investigate and clean up the Oak
Grove Sanitary Landfill. The federal Superfund monies are collected as a tax on hazardous
waste generators and from potentially responsible party reimbursements. This information
has not been included in the two agencies' information efforts. Future information will
discuss the source of federal Superfund dollars.
40. Comment: A representative of the steering committee of potentially
responsible parties concurs with the MPCA's and U.S. EPA's proposed
plan.
One group of potentially responsible parties has indicated it agrees with the agencies'
findings and intend to work with the MPCA and U.S. EPA on the cleanup.
41. Comment: The October 24, 1990 meeting intentionally misled the
community about the potential threat of the landfill to surface water and
residential wells.
The Oak Grove Sanitary Landfill does pose a threat to public health and the environment.
The shallow ground water at the site is highly contaminated with VOCs; the deep ground
water, which is used for drinking water, is at risk of becoming contaminated; the potential
impacts on the wetland and its inhabitants still needs to be investigated. It is also true that
the MPCA and the U.S. EPA have not found any residential well contamination or off-site
impacts from the landfill. These are the facts which were presented at the public meeting. It
is the policy of the MPCA and the U.S. EPA that the public has a right to know about all
potential environmental threats to their community.
42. Comment: The MPCA intentionally misled the public into believing
that contaminants had migrated to Cedar Creek.
Before the public meeting, the MPCA and U.S. EPA distributed a fact sheet and a news
release about the proposed plan for ground water. The news release contained an error,
indicating that surface wate: impacts had been detected in Cedar Creek, The fact sheet
contained cost figures on the alternative remedies that were lower than actual cost estimates.
At the October 24, 1990 meeting, the Public Information Officer who prepared these
materials apologized to the 175 - 200 members of the community who had received these
materials, including members of the local news media. This apology and corrections are
clearly noted in the transcript of the meeting. The presentation contained complete and
accurate information. The MPCA and the U.S. EPA apologize for the errors in the public
information handouts, but feel that accusations made by potentially responsible parties thai
impacts of the landfill have been exaggerated with an intent to confuse or panic the public
are completely without merit.
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43. Comment: The MPCA said at the public meeting that caps such as
the one proposed can be found at other landfills in the state. One group of
potentially responsible parties feels that this is misleading, as a cover
exactly like the one proposed for Oak Grove Sanitary Landfill has not been
built at any other facility in Minnesota.
The standard procedure for managing landfills in Minnesota is to provide a cover or cap for
the landfill and a ground water monitoring system. Many sites in Minnesota have caps,
and these caps were built under the state of Minnesota's old solid waste rules which were
not as protective as the current rules. The new solid waste rules went into effect in 1988,
and the Oak Grove Sanitary Landfill must be constructed under these rules.
If the owners and operators of the landfill had closed the facility properly in 1983, when
the landfill ceased operation, they could have built a less protective capping system at a
lower cost under the old rules. Because they chose not to address the landfill's problems at
that time, the potentially responsible parties will now have to build the more protective
cover in compliance with the new rules. Other facilities which have caps similar to the one
proposed for Oak Grove include the Anoka County Sanitary Landfill, Kandiohi County
Landfill, Olmsted County Landfill, Maple Landfill, Moonlight Rock Landfill, and Potlatch-
Goquet Landfill.
44. Comment: The MPCA has continued to "harass individuals over a
site that... is not now a threat and ... will not be a threat in the future/'
The MPCA and the U.S. EPA should let the potentially responsible parties
address the landfill's problems.
The Oak Grove Sanitary Landfill is a potential threat to public health and the environment.
Although it has not been found to have contaminated drinking water suppb'es, that potential
exists. The landfill has clearly contaminated the shallow aquifer. The statement that the
site is harmless and will continue to be so has no basis in fact
The MPCA and the U.S. EPA have addressed the Oak Grove Sanitary Landfill under
federal and state rules and regulations. The MPCA's initial request to the owners and
operators of the landfill was that they investigate and address the landfill's problems.
These potentially responsible parties chose not to work cooperatively with the MPCA and
the U.S. EPA, as is their right under the law. A lien has been filed by the U.S. Department
of Justice on the landfill property in an attempt to assure some cost recovery, and this
action was taken in compliance with all applicable laws and with due process for the landfill
owners and operators. The charge that the MPCA or the U.S. EPA have harassed the
owners and operators is without merit.
45. Comment: The November 1990 fact sheet on health issues related to
the Oak Grove Sanitary Landfill described the health assessment prepared
by the Agency for Toxic Substances Disease Registry in concert with the
Minnesota Department of Health. The health assessment covers physical
hazards, such as broken glass and crumbling buildings. The fact sheet
misled the public, because there are no buildings on the landfill site proper.
The description of the health assessment contained in the fact sheet used broken glass and
crumbling buildings as general examples of physical hazards and not specific features of
the Oak Grove Sanitary Landfill.
46. Comment: The MPCA should have allowed the potentially
responsible parties to do their own Remedial Investigation/Feasibility
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Study (RI/FS) instead of placing the site on the federal and state Superfund
lists*.
The potentially responsible parties at the Oak Grove Sanitary Landfill had many
opportunities to negotiate with the MPCA and to perform an RI/FS and cleanup actions. In
fact, most landfills in Minnesota are being addressed by responsible parties (in many cases,
county and city governments) working cooperatively with the MPCA. The potentially
responsible parties chose not to participate in 1984. The site was proposed for the state and
federal Superfund list because it posed a potential threat to drinking water supplies and
because no potentially responsible parry was willing to adequately investigate and
undertake a remedy for the site. Recently, a steering committee of potentially responsible
parties has indicated willingness to work cooperatively with me two agencies.
47. Comment: The MPCA and the U.S. EPA are requesting too many
samples too frequently in the long-term monitoring plan.
The MPCA and the U.S. EPA are proposing a long-term monitoring plan that is consistent
with the two agencies' goal: to acquire enough data to know if any changes occur in levels
of contaminants. The number of samples required will provide the MPCA and the U.S.
EPA with a sufficient data base and will also show seasonal variations.
48. Comment: The MPCA and the U.S. EPA are requesting sampling for
pesticides and polychlorinated biphenyls (PCBs) and these tests are not
necessary.
The MPCA and the U.S. EPA are requiring data on pesticides and PCBs because the
MPCA Water Quality Division staff had some concerns about these chemicals in ground
and surface water based on the Remedial Investigation. After the two agencies have
obtained sufficient data about pesticides and PCBs, and if no problems are indicated, the
two agencies may not test for pesticides and PCBs in the future.
0
49. Comment: The MPCA and the U.S. EPA have underestimated the
cost of the long-term monitoring plan and the plan to abandon monitoring
wells at the site.
The MPCA and U.S. EPA's consultant, Malcolm Pirnie, has provided cost estimates based
on the company's experience with similar sites. The cost of the long-term monitoring plan
are only estimated, and it is likely that the re/d cost will be different than the estimate
provided. It may be more or less.
REMAINING CONCERNS
There are several outstanding concerns that will be addressed by the MPCA and the U.S.
EPA through the Remedial Design and Remedial Action phases of the Oak Grove Sanitary
Landfill cleanup process:
1. The MPCA and the U.S. EPA have insufficient information about how the
contaminants found at the landfill affect the wetland. The MPCA and U.S. EPA will
sample surface water and sediments in the wetland to determine how natural processes are
breaking down the contaminants, how contaminants migrate in surface water, and what
potential effects contaminants could have on the wildlife in the area.
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2. Pursuant to enforcing institutional controls, the MPCA and
U.S. EPA may need to do a more through search to make sure that
no residents in the area of the landfill are using the shallow
aquifer for drinking water.
3. The MPCA and the U.S. EPA will continue testing residential wells as well as
long-term monitoring stations to ensure that contaminants are not affecting drinking water
or increasing. After the cap and methane venting system are complete, the long-term
monitoring will continue for 30 years to ensure that the cleanup remedy is effective in
reducing or eliminating ground water contamination.
4. The MPCA and the U.S. EPA will develop a more accurate mailing list and provide
regular information about the site to area residents. Any future public information efforts
will be coordinated with the Oak Grove Township Board and Anoka County.
5. As U.S. EPA enforcement efforts continue and potentially responsible parties are
identified, the MPCA and the U.S. EPA will provide information to interested residents,
local officials, local news media, and potentially responsible parties.
6. The MPCA will forward a transcript of the public meeting held on October 24,
1990 to the Oak Grove Township Board and St. Francis Public Library for public review.
A copy will also be forwarded to Anoka County so that the comments on Site D can be
considered by the responsible governmental unit
7. The MPCA and U.S. EPA will respond to any additional requests for information
about the site.
ATTACHMENT A
Community Relations Activities Conducted at the Oak Grove Sanitary
Landfill
The MPCA has conducted the following community relations activities for the Oak Grove
Sanitary Landfill:
November 1985 Public meeting to describe project; fact sheet.
December 1985 Community relations interviews; information repository
established at the Oak Grove Township Hall.
Spring 1985 Community Relations Plan completed.
Noven.ber 17, 1986 News release announcing beginning of field work.
December 3, 1986 . Public meeting, fact sheet on work plan.
February 1988 Update letter to mailing list about separation of source and
ground water operable units.
June 1988 Update letter to mailing list
August 30, 1988 News release announcing source control proposed plan,
public meeting.
September 2, 1988 Ad published in Anoka County Union; documents
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September 14, 1988
September 23, 1988
October 10 -15, 1990
October 24, 1990
November?, 1990
November 15, 1990
November 30, 1990
placed in information repository.
Public meeting, fact sheet provided on source control
proposed plan; comments accepted from the public.
Public comment period ended; responsiveness summary
written and attached to Record of Decision.
News release, fact sheet sent to local media, mailing list on
proposed plan for ground water operable unit; ad in Anoka
County Union published to announce meeting; reports
delivered to Oak Grove Township Hall and St. Francis
Branch of the Anoka Public Library.
Public meeting held on ground water operable unit,
approximately 175 interested parties attended.
Request received to extend the public comment period.
Comment period is extended to November 30; paid ad placed
in Star/Tribune November 18, Anoka County Union
on November 23; fact sheets and announcements sent to
all interested parties on mailing list; Anoka County Solid
Waste Officer, attorney for potentially responsible parties,
resident associated with the Egan Family verbally informed
of extension of comment period.
Comment period ended; responsiveness summary prepared.
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