~
I
United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPAIRODIR05-91 '1 89
June 1991
C of! /
?"B1z-1b4137
oEPA
Superfund
Record of Decision:
Dakhue Sanitary Landfill, MN
u . S. Environmental Protection Agency
Region III Hazardous Waste
Technical Information Center
841 Chestnut Street, 9th Floor
Philadelphia. PA 19107
HazardoUS Waste CoIIec;1ion
'"formation Resourc;e Center
US EPA RegIon 3
PhUQCIeIphta, PA 1910{ .
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, 50272.101
REPORT DOCUMENTATION 1'. REPORT NO.
PAGE EPA/ROD/R05-91/189
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So A8dpIenI'. ACC888Ion No.
4. 1118 end SubtI..
SUPERFUND RECORD OF DECISION
Dakhue Sanitary Landfill, MN
First Remedial Action
7. Aulhor(.)
5. Report De18
06/28/91
a.
.. PItrforming Organization R8pt. No.
t. ''''''onlllllg Orgelnlza1lon ...... end ~
10. Projoclf1'ulllWart& UnIt No.
11. Corm8cI(C) or GnnI(G) No.
(C)
(0)
1~ 8pon8ortng OrpnIzIIIon NIIm8 end Adch88
U.S. Environmental Protection
401. M Street, S.W.
Washington, D.C. 20460
1 So Type of Report . Pwttod Covered
Agency
800/000
14.
15. Supplem8nl8ry No..
1 a. Abetr.ct (Umlt: 200 _rd.)
The 80-acre Dakhue Sanitary Landfill site is an inactive sanitary waste municipal
landfill located in Hampton Township, Dakota County, Minnesota. Land use in the area
is agricultural and residential. The landfill overlies a sand and gravel surficial
aquifer that is not a drinking water source and that extends downgradient of the site.
However, 15 residential wells are located within 1 mile of the site, and a municipal
water supply well is located over 3 miles south of the site, all of which extract
ground water from a deeper aquifer. Investigations are ongoing to determine whether
the two aquifers are hydraulically connected. From 1971 to 1988, Dakhue Sanitary
Landfill, Inc., owned and operated the landfill and accepted mixed municipal and
commercial wastes, and small amounts of industrial waste. State investigations
conducted between 1983 and 1989 identified a variety of contaminants on site.
Investigations during the RI/FS identified VOCs, organics, and inorganics in the
surficial onsite aquifer, and it has been determined that the possible source of
contamination is related to the municipal, industrial, and commercial waste disposed
onsite in the landfill. Ongoing investigations are required to further define onsite
ground water contamination. As a result, the site will be remediated as two operable
(See Attached Page)
17. Docurn8nt An8Iy8I8 .. D88crtpt0..
Record of Decision - Dakhue Sanitary Landfill, MN
First Remedial Action
. Contaminated M~dia: soil, debris
Key Contaminants: organics (phenols), metals (arsenic, chromium, lead)
b. Id8ntHI8n/Op8n-EncI8d T-
c. COSA 11 Fl8ldlGroup
,I. Aniiabilty 9I8I8m8nt
, t. SeC\8ity CIa.. (Thl. Report)
None
20. SeC\8ity CI- (11118 Page)
Nnn~
21. No. of Page.
44
j
~ PrIce
(Sea ANSl-Z3I. t8
SH InalrUcli- on R.WtN
(Formerty NTlS-35)
Department of Collllll8rce
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EPA/ROD/R05-91/1B9
Dakhue Sanitary Landfill, MN
First Remedial Action
Abstract (Continued)
units (OUs). This ROD addresses the source of the contamination as OU1. A future ROD
will address ground water contamination and possible remediation of the downgradient
plume, as OU2. The primary contaminants of concern affecting the soil and debris are
organics including phenols; and metals including arsenic, chromium, and lead.
The selected remedial action for this site includes capping the site with a final cover
system consisting of a gas control layer, a barrier of low-permeability material, and a
drainage layer; revegetating the area; treating air emissions from gas vents; conducting
air and ground water monitoring; and installing a fence around the site perimeter. The
capital cost for this remedial action is $9,BOO,000, which includes an estimated annual
O&M cost of $54,000 for 2 years.
PERFORMANCE STANDARDS OR GOALS:
Not applicable.
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Record of Decision
Site Name and Location
Dakhue Sanitary Landfill Site
Hampton Township, Dakota County, Minnesota
Statanent of Basis and Support
This decision d.cx:::tm1ent presents the selected source control operable unit
remedial action for the Dakhue Sanitary Landfill Site, in Hampton Township,
Dakota County, Minnesota, developed in accordance with the Ccrnprehensive
Environrrental Response, Compensation, and Liability Act of 1980 (CERCIA), as
amended by the Superfund Amendrrents 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
based upon the contents of the administrative record for the Dakhue Sanitary
Landfill site. The attached index identifies the items which ccrnprise the
admini,strative record. The Minnesota Pollution Control Agency's decision is
baseq'in accordance with the Minnesota Environrrental Response and Liability Act
of 1983.
The state of Minnesota and the U.S. Environmental Protection Agency (USEPA),
each and independently, concur and adopt the selected rem:rly. The property
deed will be recorded as a hazardous waste site in confonnance with Minnesota
Statute.
Assessment of the site
Actual or threatened release of hazardous substances fran this site if not
addressed by irnplemanting the response action selected in this Record of
Decision (ROD), may present an imninent and substantial endangenrent to public
health, welfare, and the environment.
Description of the Selected Remedy
This operable unit is the first of two operable units for the site. The first
operable unit addresses the source of the contaI'nination by containing the
on-site wastes and contaminated soil. The function of this operable unit is to
provide a final cover for the Dakhue Sanitary Landfill which will prevent or
minimize ground water contamination and risks associated with exposure to the
contaminated materials. The remedy does not fully address the principal
threats at the site because it is not appropriate to address the ground water
contamination at this tinE. The second operable unit will address the ground
water contamination and possible rem=diation of the downgradient plume.
The major canponents of the selected remedy include:
*
Installing a security fence around the landfill site,
* Capping with a final cover system consisting of a gas control layer, a
barrier layer of low penreable material, and a drainage layer,
* Topsoil cover and vegetation,
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* Treatment options for air anissions fran gas vents will be considered after
construction of the final cover,
* Air and ground water m:mitoring to ensure the effectiveness of the raneclial
action will be implatented after construction of the final cover.
This action will require operation and maintenance activities to ensure
continued effectiveness of the raneclial al ternati ve. The action being taken is
consistent with Section 121 of CERcrA, as amended by SARA, 42 U.S.C. S 9621.
Declaration
The selected raredy is protective of human health and the environment, canplies
with Federal and State requirEments that are applicable or relevant and
appropriate, and is cost effective. This raredy utilizes pennanent solutions
. and alternative treatment technologies to the maximum extent practicable for
this site. However, because treatment of the principal threats fran the site
were not fmmd to be practicable, this raredy does not satisfy the statutory
prefe+ence for treatment as a principal elatent. The size of the landfill plus
the fact that there are no on-site hot spots that represent major sources of
contamination preclude a raredy in which contaminants could effectively be
excavated and treated.
Because this remedy will result in hazardous substances remaining on-site above
health-based levels, a review will be conducted within five years after
carmencement of raredial action to ensure that the remedy continues to provide
adequate protection of human health and the environment.
D>ted: :J:;e 2g ,~99/ ~ ~ f
I
Dated:
s
trator
JOY
Charles W. Williams
Carrnissioner
Minnesota Pollution Control Agency
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SUMMARY OF REMEDIAL ALTERNATIVE SELEcrION
Dakhue Sanitary Landfill
Hampton Township, Dakota County, Minnesota
1.
SITE NAME, LCX:ATION, AND DESCRIPTION
DJcation
The Dakhue Sanitary Landfill (DSLF) is located in Hampton Township,
Dakota County, Minnesota (figure 1), off of Hogan Avenue as shown in
Figure 2. The Dakhue Sanitary Landfill is approximately 30 miles south
of St. Paul, the state capital.
Site Description
The Dakhue Sanitary Landfill is located in southeastenl Dakota County,
within the Rochester Till Plain Physiography region of Minnesota. The
area of the landfill is associated with a topographic ridge trending
northwest-southeast across the site. 'lb the south of the landfill the
topographic ridge ends abruptly foDTIing a series of gullies which drain
into a dry creek bed. Farther to the east and south of the landfill the
terrain is relatively flat, cooq:>osed of open and cultivated fields.
The adjacent land is used primarily for agriculture with saTe residential
plots intennixed.
The Dakhue Sanitary Landfill is developed over a sand and gravel water
table aquifer which is present throughout the site and extends
downgradient of the site. Only the oottaTI 20 to 30 feet of the glacial
drift are saturated.
Based on well logs fran residential and irrigation wells in the area, and
on resistivity values fran the 1985 hydrogeologic investigation, Liesch
( 1985) concluded that there appears to be no hydraulic barrier between
the drift aquifer and the underlying Prairie du Chien aquifer. This lack
of hydraulic barrier is substantiated by the similar variations of ground
water elevations in wells MW-2 and BAL-1, ooth screened in the sand and
gravel aquifer, and Well MW-1 open hole in the Prairie du Chien aquifer
(Figure 3). Figure 3 was drawn using ground water elevations published
in the Evaluation Report (Liesch 1987).
Based on ground water elevations maasured in Wells MW-1, MW-2 and BAL-l,
Li~sch (1987) concluded that ground water flaws in a southeasterly to
southwesterly direction with a hydraulic gradient of 0.008 feet/foot.
II.
SITE HIS'roRY
The Dakhue Sanitary Landfill is owned and was operated by Dakhue Sanitary
Landfill, Inc., a Minnesota corp:>ration. The landfill is located in
southern Dakota County approximately 3 miles north of Cannon Falls,
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III.
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Minnesota~ The location of the landfill is shown on Figure 1. Dakhue
Sanitary Landfill, Inc. purchased the property in 1971 for the purpose of
developing a sanitary landfill.
Prior to 1971, the land within the site boundaJ:y was primarily
undeveloped. On O::tober 1, 1971, the Minnesota Pollution Control Agency
(MPCA) issued a Solid Waste Disposal Facility pennit SW-50 (pe:rmit
number) for an 80-acre operation at the Dakhue site to Dakhue Sanitary
Landfill, Inc. As part of this pennit requiranent, Dakhue Sanitary
Landfill, Inc. installed two on-site rronitoring wells in O::tober 1971.
M::>nitoring Well MW-1 was installed upgradient, and M::>nitoring Well MW-2
was installed downgradient of the refuse area.
The landfill was initially open on a part-titre basis (three days a week)
until 1973, when the landfill extended its operation to six days a week.
Dakhue received an up::iated or amanded pennit fran the MPCA on July 25,
1983.
Dakhue Sanitary Landfill operated until May 31, 1988, at which titre waste
disposal activities ceased. Fran O::tober 1971 to May 1988, the landfill
was utilized for the disposal of mixed municipal and cam\E!rcial waste,
and small am::>unts of industrial waste.
In a letter dated July 22, 1988, representatives of the landfill owners
stated that Dakhue Sanitary Landfill, Inc. was financially unable to
undertake closure and postclosure activities necessary at the landfill.
On O::tober 11, 1988, DakhueSanitary Landfill, Inc. filed for Chapter 11
bankruptcy.
The facility was originally scored using the Hazardous Ranking Systen
(HRS) on Septanber 29, 1985. On June 23, 1987, the pennittee, signed a
Response Order by Consent with the MPCA. The HRS scoring package was
amanded on May 23, 1988, and in March 1989. The facility is currently
on the State's Pennanent List of Priorities and is on the U.S.
EnvirormEIltal Protection Agency's (EPA) National List of Priorities with
a score of 42.
Additional infonnation can be found in the Evaluation Report (Liesch,
1987).
SUMMARY OF SITE QIARACl'ERISTICS
RI activities were initiated at the Dakhue Sanitary Landfill in 1990 and
are currently ongoing. The activities and results obtained to date will
be briefly sumnarized in this section. However, it should be noted that
the data and hydrogeological results presented here are preliminary and
will be subjected to further refinanent during the migration managerent
operable unit RIfFS.
On-site rronitoring wells were sampled by the MPCA and analyzed for VO:::s
by the Minnesota Deparbrent of Health (MDH) between 1983 and 1989. The
results of the individual sampling events are presented in Table 1.
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Except for a one-time detection of trichloroethene (detected May 1987, at
1.5 mg/l), no VOCs were found in the upgradient well MW-1. Twenty-five
VOCs were detected in the downgradient wells (22 in MW-2 and 21 in
BAL-1). Chlorinated cayqx>unds were the primary class of VOCs detected.
Of these, chlorinated ethenes and ethanes were detected with the greatest
frequency and. at the highest concentration. The data suggest that the
chlorinated ethenes and ethanes are being degraded fran mre chlorinated
(e. g ., tetrachloroethane) to less chlorinated cayqx>unds
(e.g., 1,2-dichloroethane). Other classes of VOCs detected in the ground
water include arcmatic hydrocarbons (e. g ., benzene) and ether cayqx>unds.
Residential wells near the Dakhue Sanitary Landfill were sampled by MPCA
staff on several separate occasions. The samples were analyzed for
volatile organic cayqx>unds (VOCs) by the Minnesota Department of Health.
None of the residential wells samples' are known to be contaminated.
Extent of Contamination
Results fran the analyses of samples document the presence of a variety
of cayqx>unds. The 1IDst ccmron of these cayqx>unds are benzene, Jrethy lene
chloride, cis-trans 1,2, dichloroethene, ethyl ether, tetrahydrofuran and
trichloroethene. Further investigation is ongoing and is required in
order to characterize the extent and magnitude of the ground water
contamination at the Dakhue Sanitary Landfill site, especially in the
deeper aquifer. As described in section V, the migration managanent
operable unit will address this portion of the project.
Many organic and inorganic ccmpounds were detected. in ground water
samples collected during the RI conducted at the Dakhue Sanitary
Landfill. Tables 1 and 2 present on-site contaminant infonnation.
Residential Wells
A review of records indicated that there are 15 wells within
approximately 1 mile of the site. The nearest well (Dahlin) is
. approximately 1500 feet upgradient fran the site. The nearest
downgradient residential wells, Spillman and Callister, are approximately
1/2 mile southwest and southeast of the site, respectively. The nearest
municipal water supply wells are located over 3 miles south of the site.
These wells are south of the Cannon River which is believed to be south
of the regional ground water discharge for the site.
At this tinE, there is no identified contamination of water supply or
irrigation wells. The wells nearest to the site were last sampled for
volatile organic cayqx>unds by the MPCA in February 1991 and no
contamination was identified.
Source of Contamination
There is no discrete source of contamination other than mixed municipal
waste at the Dakhue Sanitary Landfill. Most of the waste present at the
landfill is household trash and gart:>age. A small quantity of industrial,
camercial waste was disposed of at this site.
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The chemicals detected at the site are consistent with sane of the waste
streams (e. g., paint, solvents) thought to have been disposed of in the
landfill.
IV.
SUMMARY OF RISKS
The infomation gathered in developing the conceptual site m::x:lel is
being used to rrake this preliminary assessment of public health and
envirornnental risks fran the Dakhue Sanitary Landfill site migration
control (ground water) operable unit.
For the PUrpose of this preliminary risk characterization, the only
exposure pathway preliminary assessed in a quanti tati ve manner is the
ingestion of ground water in a residential water supply setting. Risks
(carcinogenic and noncarcinogeniC) were assessed based on data from MW-2
and BAL-1. The highest detected contaminant concentrations detected in
ground water in either well were used in this preliminary assessment.
Twelve carcinogens were detected at the'site in the gI."Ound water. Table
3 presents for a residential use setting, the excess lifetime cancer risk
associated with ingestion of ~}f1d water. The excess lifetime cancer
risk was estimated to be 6 x 10 . Eleven of the carcinogens were -6
detected at concentrations associated with risks greater than 1 x 10
Table 4 cc:mpares estimated intakes of noncarcinogenic caopounds to
reference dose (RfD) values. No RfDs are exceeded by the estimated
intakes.
V. . SCOPE AND ROLE OF OPERABLE UNIT
Since further work is needed to canplete the RIfFS for the ground water
. contamination, which was started in CX::tober 1990, the USEPA and MPCA
agreed to divide the project into two operable units in order to
facilitate progress toward raIEdial action at this site. The two
operable units are for source control and. migration management. The
first operable unit will address the source of the contamination by
containing the on-site wastes and contaminated soils. The second
operable unit will involve further study of the ground water
contamination and will address raIEdiation of the downgradient
contaminant plune. The role of each operable unit will be further
explained below.
Source Control Operable Unit
The Dakhue Sanitary Landfill never received final cover when the landfill
was closed. MPCA and USEPA consider it expedient to procede with
contairnnent of waste as quickly as possible in order to prevent further
infiltration of precipitation and subsequent leachate generation.
Therefore, the MPCA, in conjunction with the USEPA, decided to proceed
with a Focused Feasibility Study (FFS) to deteD"lline what type of final
cover would be suitable for the site.
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Miqration Managarent Operable Unit
This operable unit is currently still in the Rem3dial Investigation
phase. The preliminary results of the RI indicate the presence of
contamination in the upper aquifer, but further work is necessary to
detennine the canpetency of the confining layer that lies between the
upper and lower aquifer, and to deteDnine if the lower aquifer is being
contaminated by the Dakhue Sanitary Landfill. Sare of the remaining
tasks to be perfo:cred include installation of additional m::mitoring
wells, perfOI:mance of a series of slug tests, collection and analysis of
additional water samples, and preparation of the final RI report. The FS
will be initiated after canpletion of these RI activities.
VI.
COMMUNITY RElATIONS
The source control alternatives evaluated in the FFS were presented to
the. interested carmunity in a manner consistent with CERCI.A Section
113(k) (2) (B) and Section 117, and EPA guidel°ines on conmunity relations,
at the conclusion of the FFS.
A public carment pericx:l. on the alternatives began on April 30, 1991, and
ended on May 30, 1991. The MPCA published a notice in the April 18,
1991, edition of the Cannon Falls Beacon, the local newspaper, and also
provided a news release to the paper. The notice included infonnation on
the availability of the FFS and Proposed Plan at the Cannon Falls Public
Library, the dates of the public cament period and public meeting, and a
description of the alternatives and the proposed alternatives. In
addition, on April 20, 1991, the MPCA mailed a copy of the notice and
news release, which explained in nore detail the proposed al ternati ve, to
persons on the Dakhue site mailing list. This mailing list includes
interested residents, township and county officials, elected officials,
and site owners and operators. The Cannon Falls Public Library served as
the infonnation repository for the ~strative Record, the FFS and the
Proposed Plan.
A public meeting was held on April 30, 1991, in the Cannon Falls Senior
High School. The attached Responsiveness Surrma:ry lists the ccmnents
received at the meeting and during the cament period, as well as the
MPCA's response to those carments.
VII.
DESCRIPI'ION OF ALTERNATIVES
The alternatives under consideration for source control were developed by
examining a number of possible raredi.al technologies, and canpliance of
these alternatives with applicable or relevant and appropriate
requi.rerrents (ARARs) of federal and state envirormental statutes.
Excavation of the landfill (with destruction of the wastes by
incineration and disposal of the residues off-site in a secure carmerc ial
landfill, or re-disposal on-site in a lined landfill) was eliminated in
the initial screening process. The criteria used for elimination of
excavation were short-tenn impacts on hmnan health due to air emissions
and excessive
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cost. Alternative cover systems for in-place closure of the landfilled
waste, were considered and evaluated in accordance with the requirements
of National Contingency Plan (NCP), 40 CFR Section 300.430.
The source control alternatives are:
Al ternati ve 1:
No Action
Alternative 2: Cover system satisfying Minnesota Rules for municipal
landfill closure with clay barrier layer.
Alternative 3: Cover system satisfying Minnesota Rules for municipal
landfill closure with two feet additional frost protection.
Alternative 4:
closure.
RCRA Subtitle C cover system for hazardous waste facility
All alternatives except "no action" would include capping the former
disposal area with varying layers and thicknesses of soil and! or
synthetic ma.terials which in canbination would cc:mprise a cover system
for the landfill. Each alternative cover system described below includes
a foundation layer overlying existing ma.terials to support the cover
system and a continuous coarse-grained soil layer in conjunction with gas
vents which will be utilized to control gas migration. The differences
in the alternative cover systems consist of varying thicknesses of cover
soil, the presence and thickness of a lateral drainage layer and the type
of barrier layer utilized to minimize percolation of surface water. The
cover systems would provide varying degrees of control of contaminant
migration into ground water and surface water by minimizing percolation
of rainfall and snow melt through the landfill contents. .
Al ternati ve 1:
No Action
Construction Cost:
None
Annual Operation and Maintenance (O&M) Costs:
None
Cc:mprehensive Envirornnental Response, Cc:mpensation, and Liability Act of
1980 (CERcrA) requires that the "no action" alternative be considered at
every site. Under this alternative, MPCA would fence the site to prevent
direct h\.mlaJ1 contact with landfilled wastes, but take no further action
to control the ability of contaminants to migrate.
Alternative 2: Cover system satisfying Minnesota Rules for municipal
landfill closure clay barrier.
Construction Cost:
Arumal O&M Costs:
$7,600,000
$ 53,000
Alternative 2 cover system consists of grading and soil fill to construct
a foundation layer with minimum 3 percent slopes, a gas control layer of
six inches of sand, a barrier layer of 24 inches of clay and a 24 inch
vegetated cover layer, including a six inch drainage layer.
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Alternative 3: Cover systan satisfying Minnesota Rules for municipal
landfill closure with two feet additional frost protection.
Construction Cost:
Annual O&M Costs:
$9,800,000
$ 54,000
Alternative 3 cover systan consists of grading and soil fill to construct
a foundation layer with miniIm.nn 3 percent slope, a gas control layer of
six inches of sand, a barrier layer of 24 inches of clay, a 12 inch sand
lateral drainage layer, and a 36-inch vegetated cover layer.
Alternative 4:
facility.
RCRA Subtitle C cover for closure of a hazardous waste
Construction Cost:
Annual O&M Costs:
$13,000,000
$ 54,000
Alternative 4 cover systan consists of grading and soil fill to construct
a foundation layer with miniIm.nn 3 percent slope, a gas control layer of
six inches of sand, a barrier layer of 30 mil thickness high density
polyethylene liner and 24 inches of clay, a 12-inch sand lateral drainage
layer and a 48-inch vegetated cover layer.
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The NCP and Section 121 of the Superfund Anendments and Reauthorization
Act. of 1986 (SARA) fom the regulatory basis for the nine evaluation
criteria utilized in deteIInining the appropriate ratEdial action at a
CERCIA site. Specifically, Section 121 of SARA requires that the
selected reredy is to be protective of human health and . the
envirornrent, cost-effective, and use pennanent solutions and alternative
treatment technologies or resource recovery technologies to the maximum
extent practicable. .
Alternatives were evaluated using current USEPA guidance, including
"Guidance for Conducting Remedial Investigations and Feasibility Studies
under CERCIA" OSWER Directive 9355.3-01, October 1988; "A G..1ide to
Selecting Superfund Remedial Action," OSWER Directive 9355.0-27FS, April
1990; and "Streamlining the RIfFS for CERCLA Municipal Landfill Sites,"
OSWER Directive 9355.11-11FS, September 1990. The nine evaluation
criteria, referenced in the first two guidance documants above, are as
follows:
* Long '!'em Effectiveness - The analysis under this criterion fcx:uses on
any residual risk remaining at the site after the canpletion of the
..ranediaJ. action. This analysis includes consideration of the degree
of threat posed by the hazardous. substances remaining at the site, the
adequacy of any controls (e.g., engineering or institutional control)
used to manage the hazardous substances at the site, and the
reliability of controls against possible failure.
* Reduction of Toxicity, Mobility, and Volmre - This evaluation
criterion addresses the statutory preference for selecting ranedial
actions that anploy treatnent technologies that pennanently and
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significantly reduce the toxicity, rrobility, and vohune of hazardous
substances asa principal element.
*
Short-TeD11. Effectiveness - This evaluation criterion addresses the
effects of the alternative during the construction and implanentation
phase until the ranedial response objectives are met. Under this
criterion alternatives are evaluated with respect to their effects on
human health and the environment during the implementation of t.he
ranedial action.
*
:rIDplanentability - The irnplanentability criterion addresses the
technical and administrative feasibility of implanenting an
alternative and the availability of various services and naterial .
required during its implanentation.
* Cost - The estimated capital, annual maintenance and rronitoring, and
present worth value costs are evaluated under this criterion. Present
worth costs are calculated using a ten percent discount rate over a 50
year period of operation. Cost estimate s1..ID11\aries of alternative
cover systans are given in Appendix B.
* Overall Protection of Human Health and the Environment - This
evaluation criterion draws on the results of the above evaluation
criteria to describe whether, and how, each alternative provides
protection of human health and the environment.
* Canpliance with ARARs - This evaluation criterion is used to deteD11.ine
whether each alternative will meet all of its federal and state ARARs
(as defined in CERCIA 121). The detailed analysis should s1..ID11\arize
which requirements are applicable or relevant and appropriate to an
al ternati ve and describe how the al ternati ve meets those requiranents.
When an ARM is not met, the detailed analysis should discuss whether
one of the six waivers allowed under CERCI.A may be appropriate.
*
Carmunity Acceptance - This criterion refers to the carmunity's
c
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Alternative 4 is most effective as it virtually eliminates leachate
production. Alternative 3 prcx:iuces less leachate quantities than
Al ternati ve 2. No action is not protective because contaminants will
continue to. leach into ground water and surface water at an unacceptably
high rate of transfer.
Ccmpliance with ARARs
Alternative 1, no action, does not ccmply with state and federal
:regulations for landfill closure. The remaining alternatives correspond
to applicable closure regulations as follows:
* Alternative 2,3,4, meet applicable state requiranents for closure of a
mixed municipal solid waste facility. RCRA Subtitle C regulations
are not applicable to Dakhue Sanitary Landfill because RCRA hazardous
wastes are not present. It is our professional judgment that based on
available research there is no characteristic RCRA hazardous waste in
the landfill.
* Alternative 4 neets ReM subtitle C requiranents for closure of a
hazardous waste facility. Subtitle C requiranents are much more
stringent and therefore, Alternative 4 significantly exceeds Mirmesota
requirements for mixed municipal landfills. Subtitle C regulations
are not considered or relevant and appropriate for this site, in
accordance with CERClA guidance, because there are low concentrations
of a hazardous constituents dispersed over a wide area. See CERClA
Canpliance With Other Laws Manual, Office of Emergency and RE!"!edial
Response, Interim Final EPA/540/G-89/006. August 1988, pp. 2-6,7.
All alternatives will likely canply with air quality ARARs and health
- based criteria for volatile organic emissions.
wng-Tenn Effectiveness and Pennanence
The magnitude of residual risk varies with the estimated volUITE of
leachate produced. The RCRA design Alternative 4 is the rrost effective
cover because leachate generation is virtually eliminated with initial
efficiencies approaching 100 pe:rcent.
The other alternatives have estimated initial efficiencies of 97.0
pe:rcent for alternative cover systE!1\ 3 and 96.8 pe:rcent for alternative
cover systE!1\ 2. The no action alternative would allow for continual and
unabated production of leachate. None of the alternative cover systens
will prevent future contaminant migration if water table fluctuations
should cause ground water to cane into contact with landfilled wastes.
It is very unlikely that waste would cane in contact with ground water at
this site because water table is so far beneath the waste.
The long-tenn adequacy of all land disposal cover systems is unknown.
Differential settling of the landfill wastes with subsequent detr.iIrental
effects on any cover systE!1\ installed should be expected.
-------
-10-
Surface erosion, burrowing animals, and vegetation nay all penetrate the
barriers resulting in a localized failure of the barrier. Alternative 2
is the mJst likely to fail by these mJdes due to the minimal thickness of
the cover soil protecting the barrier. Alternative 3 is less likety, and
Alternative 4 is least likely to be fully penetrated, but both
al ternati ves can be damaged. by these failure mJdes.
Frost action can damage the barrier layer and reduce i ts effectiveness.
Al ternati ve 2 has the greatest potential for frost damage because the
barrier layer is above the frost line which is approximately 36 inches
beneath the surface in the Cannon Falls, Minnesota area. It is
therefore, likely that this alternative would require mJre naintenance
and repair work than the other cap designs. Al ternati ve 3 mitigates
frost damage by using enough cover soil to place the barrier layer
beneath the frost line. Al ternati ve 4 has the least chance of being
affected by frost penetration as the four feet of cover soil places the
baI:rier layer well below the frost line.
Reduction of Toxicity, Mobility, or Volume
l>bne of the alternatives include treatment technologies.
Short-TeDn Effectiveness
Minimal differences exist aITDng alternatives with respect to the
short-teDn effectiveness criterion. Minimal risks to the public are
likely under all alternatives because in-place wastes will not be
substantially disturbed. The construction will generate significant
. truck traffic to deliver required fill naterial. Alternative 4 will
generate the greatest traffic volune, Alternative 2 will generate the
least.
WOrkers nay be exposed to air anissions of volatile organic canpounds and
methane during site grading and placarent of initial layers. However,
all cover systems share these activities. Air mJnitoring and possible
respiratory protection will be required.
All alternatives have similar estinates of 1 to 2 years for design and
construction depending on the allowed bid period, approval to proceed by
the Agencies, and size of the contractor awarded the project. The
required time for construction of Alternatives 2 or 3 is likely to be
less than for Alternative 4.
Implarentability
All cover systems are technically feasible, and materials and required
services are readily available in the St. Paul area. Alternative 4 cap
design would be mJre difficult to construct because of the FML (Flexible
Membrane Layer) layer. Caupetitive bidding by qualified contractors is
expected for all alternatives with a number of national nanbrane liner
manufacturers expected to bid as the manufacturer and installer of
SYnthetic nanbrane.
-------
-11-
All cover systat1S are administratively feasible, with miniroal
requi.ranents for MPCA approvals or permits because no off-site actions
are included.
Cost
All cost estimates are sensitive to unit costs for soil, topsoil, and
clay fill. Alternatives which require greater quantities of fill, such
as 3 and 4 are m:>re sensitive to costs than Alternative 2 which requires
lesser quanti ties. Al ternati ve 2 is the lowest cost cover systan.
Alternative 3 is m:>re costly, and Alternative 4 has the greatest capital
costs.
State Acceptance
The state of Minnesota supp:>rts the preferred al ternati ves.
Ccmnunity Acceptance
Ccmnunity acceptance of the preferred alternatives has been evaluated
and is described in the Resp:>nsiveness Surrmary.
IX.
SELECl'ED ALTERNATIVE
Based on current infm:mation, the USEPA and MPCA select Alternative 3
(Figure 4) as the m:>st appropriate alternative for the final cover at the
Dakhue Sanitary Landfill. Alternative 3 provides the best balance of
tradeoffs with respect to the nine evaluation criteria for selecting a
remedial action alternative. Alternatives 2,3, and 4 are protective of
htnnan health and the enviroIlllEnt, and canply with ARARs. None of the
alternatives utilize treatment because treatment is not considered
practicable for this operable unit. Alternative 3 is the rrost
cost-effective. Alternative 3 provides adequate long te:rm effectiveness
because of frost protection, whereaS Alternative 2 is questionable in
that regard. Alternative 4 also provides adequate long te:rm protection,
however, Alternative 3 is substantially less expensive and provides.
adequate long te.nn protection as well.
x.
STATUroRY DETERMINATIONS
A.
Protection of Human Health and the Envirornnent
The selected remedy will reduce the generation of leachate by
infiltration, thereby reducing the release and subsequent hann or
p:>tential ha:rm to public health, welfare and the enviroIlllEnt. A
release of contaminants has been ciocunented in the surficial aqui fer
at toxicologically significant concentrations. Although the surf.i.cial
aquifer is w1likely to be used as a drinking water source, migration
of contaminants fran the surficial aquifer into the deeper aquifer is
p:>ssible. The selected remedy will decrease the likelihood for
degradation of the deeper aquifer which is currently used for
individual p:>table water supplies in the vicinity of the site and is
capable of yielding larger quantities of water for camercial and
public uses where necessaIy.
-------
-12-
Additional RI activities are necessary to determine if the deeper
aquifer is contaminated or if it is vulnerable to contamination. The
selected ranedy will not address the release of contaminants via
lateral IOOVement of ground water through source material at the
down gradient side of the fill area nor the continued production of
1eachatethrough infiltration subsequent to p1acenent of the cover.
This release as well as an appropriate ranedy for the deeper aquifer
will be addressed through another FS and ROD after the RI activities
are ccmpleted.
B.
Attairnnent of Applicable or Relevant and Appropriate Requirements
(ARARs )
Canpliance with ARARs
SARA requires that remedial actions meet legally applicable or .
relevant and appropriate requirements of other envirornnental laws.
These laws may include but are not limited to: the Toxic Substances
Control Act, the Safe Drinking Water Act, the Clean Air Act, the Clean
Water Act, the Solid Waste Disposal Act (RCRA), and any state law
which has stricter require!m:mts than the corresponding federal law.
Applicable requirements are cleanup standards, standards of control,
and other substantive envirornnental protection requirements, criteria
or limitations pranulgated under federal or state law that
specifically address a hazardous substance, pollutant, contaminant,
remedial action, location or other circumstance at a site. A
requirement is "applicable" if the remedial action or circumstances at
the site satisfy all of the jurisdictional prerequisites of the
requirement. .
Relevant and appropriate requirements are cleanup standards, standards
of control, and other envirornnental protection requirements, cr iter ia
or limitations prcmulgated under federal or state law that, while not
legally "applicable" to a hazardous substance, pollutant, contaminant,
remedial action, location or other circumstance at at site, address
problems or situations sufficiently similar to those encountered at
the site that their use is well suited to that site.
"A requirement that is judged to be relevant and appropriate must be
canplied with to the sane degree as if it were applicable. However,
there is nore discretion in this detennination: it is possible for
only part of a requirarent to be considered relevant and appropriate,
the rest being dismissed if judged not to be relevant and appropriate
in a given case" (Interim Guidance on Canpliance with Applicable or
Relevant and Appropriate Requirements, 52 FR 32496, August 27, 1987).
Landfill Closure Requirements
The RCRA regulations which govern Hazardous Waste Treatment, Storage
and Disposal facilities (40 CPR Parts 264 and 265) apply to landfill
facilities that received hazardous waste after Novanber 19, 1980. It
has not been documented, at present, that any hazardous waste was
disposed of at Dakhue Sanitary Landfill following Novanber 19, 1980.
-------
-13-
The RCRA, Subtitle C requirements for hazardous waste landfill closure
are not applicable at this site.
Dakhue Sanitary Landfill was a sanitary landfill which received a
small docUITented quantity of hazardous waste which is dispersed
throughout a large volume on non-hazardous Il'aterial. The presently
docUITented proportion of hazardous waste is based on records received
fran Dakota County files. The USEPA does not regard RCRA Subtitle C
regulations as relevant or appropriate for a large sanitary landfill
where small quantities of hazardous substances have been disposed of
aIrong a much larger volume of ordinary solid waste. "
The Minnesota regulation governing municipal landfill closure,
[7035.2815, Subp. 6.(3)] are applicable, to closure of the Dakhue
Landfill. This regulation reflects RCRA Subtitle D landfill closure
requirements for solid waste landfills. While rec:QgTlizing the
applicability of this regulation to the landfill, at this site, it is
not deemed protective. As discussed earlier, this type of cover
alternative is highly susceptible to frost and sL-uctural danage.
Moreover, sane hazardous waste, albeit a small quantity, has been
documented to exist in the landfill. . Thus, the USEPA is canpelled to
increase the protectiveness afforded by the cover, required by
Minnesota and RCRA Subtitle D, and believes it is obtained by
Al ternati ve 3.
C.
Cost Effectiveness
The selected remedy will be consistent with the overall site strategy
for restoring the ground water and soils to acceptable cleanup levels.
The selected .Lt2I~ is the least expensive of the alternatives which
meet site cleanup goals.
D.
Utilization of Pennanent Solutions and Al ternati ve Treatment
Technologies or Resource Recovery Technologies to the Maximum Extent
Practicable/Preference for Treatment
IX.
The selected ramdy meets that statutory requiranent to utilize
pennanent solutions and treatment technologies to the maximum extent
practicable. Treatmant of the landfill contents was not considered
practicable because of its large size, low concentration of hazardous
constituents and the fact that there are no hot spots that represent
Il'ajor sources of contamination. Another operable unit, for the
migration management portion of this project, will address possible
remadi.ation of the ground water and will consider treatment as a
principal elatent of the overall site strategy.
~ntation of Siqnificant Changes
The Proposed Plan for this Dakhue Sanitary Landfill Site was released for
public carment in April 1991. The Proposed Plan identified Alternative 3,
a solid waste cover with additional cover soil to guard against frost
damage, as the preferred alternative. EPA and MPCA reviewed all written
and verbal carments during the public carment period. Upon review of
these Catmants, it was deteD11ined that no significant changes to the
remedy, as it was originally identified in the Proposed Plan, were
necessary.
-------
: .:-._0 ..;.....---
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Residential Well-
() Groundwater Monitoring
Location and MSG Unique
Well Number I f Available
FIGURE 2
RESIDENTIAL WELL LOCA TIONS
Dakhue Sanitary Landfill
-------
I'
~ .
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905
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-------
PROPOSED FINAL SURFACE GOOD VEGETATION
VEGETATIVE
LAYER
, \
TOP SOIL O.
COVER SOIL 2.
DRAINAGE LAYER 1.0
BARRIER LAYER
LOW PERMEABILITY MATERIAL 2.
(2 X 10.6 em/see)
GAS CONTROL LAYER O.
FOUNDATION LAYER 2.
REFUSE 0-
ft
5f1
5ft
Oft
5f1
Oft
50.0 f1
ALTERNATE COVER SYSTEM 3
DAKHUE SANITARY LANDFILL
-
FIGURE 4
/
,.
-------
TABLE i
SUmtARY OF GROUNDWATER QUAL I TY DATA
DAKHUE SANITARY LANDFILL SITE
On.Slle Downaradient We II s Oil-Site Downaradient Wells
t.fi/. Z BAL. I We II 2A We II 3A Well 4A
Chemical . 6/83 7/85a l.Lli a 5/87 4/89 7/85~/85a 5/87 4/89 J..!1ilL 10/89 .LQL1L
Benzene O. 5 4. I 2.8 I. 9 6 2
Carbon Tet rachlor ide 1.1 1.6
Ch I or obenzene 6 5. I ~6 27
Chloroethane 2
Chlorolorm I. I 2. 5 2 1.8 3. 2 0.3
Cyc lohnane I. 7
I. 4.Dichlorobenzene I
I, I.Dichloroelhane I. 3 4. 7 4. 8 4.6 6 8 7. 7 9 8 40 2. 8
1,l.Dlchloroethene O. 9 1.5
i, 2-Dichloroethane 6. 3 0.5 I. I
cis-I.2 Dichloroethene 2. 4 21 30 23 15 14 16 6. 5 5 I 1.5
trans. I, 2 Dlchloroethene O. 9 0.8 I. I 8.6
I, 2-Dichloropropane I I. I 0.4 6. 9 O. 3
Olethyl e I her 47
Et hy I e 1 her 24 150 130 ] 4 30
Methylene chloride 16 20 25 23 4 59 61 55 25 I. 7
Tetrahydrofuran 10 110
Toluene. 8. 4 7 3
1,l.l.Trlchloroethane 2. 6 4.2 8. 4 2.2 I 34 31 50 3.3 O. 9 3. I
1,1. 2.Tr Ichloroethane 0.5 O. 7 2
Trlchloroethene 7.6 10 17 9. 6 5 4 IS 20 19 60 I. 3
1,1,2. 2.Tetrachloroelhene 170 160 160 45 21 210 190 180 93 3. 9 10
Trlchlorol luoromelhane 1.9 3 5. 7 2. 5 I 16 21 21 22 O. 6 2. 5
1,1, 2.Trlchlorotrl.
lIuoroethane 4 3
Xylenes 1.6 I. 5 8. 9
Vinyl chlor Ide
All unitspg/L. :Two sets 01 analysis per formed by Minnesota Departmenl 01 Health.
. Peak detected but not quantified.
-------
TABLE 2
CONVENTIONAL POLLUTANTS
DAKHUE SANITARY LANDFILL SITE
Parameter Un i Is Averagea Averagea BAL. I (7/84) BAL. I (10/85)
Concenlralion MW.I Concenlrat ion MW.2
COD mg/L 14 63 37. 5 < l. 0
N i tr a Ie ° N It r 0 R en mR/L I. 2 1 <1.0 < l. 0
Chlor ides mg/L S. 1 25 3 36 11
pt; un i IS 8. 9 7. 1 6. 5 7
Ammonia mg/L '1.2 o. 98 . I. 73 o. 73
Su I f a I e maiL 14 86 320 27
TSS mg/L 22 550 439
TDS mQ/L 54 561 2250
Calcium mg/L (7, 1) (240) (250)
Magnesium maiL (2.4) (50) (58)
Pota3sium maiL (I. 0) (I. 0) (2.0)
Sodium mQ/L (3. 3) (6. 5) (11)
Cyanide maiL .004
Arsenic ~R/L ( < l. 0) 2.7(1.0) ( I. 0) . .
Cadmi um /Jg/L (D. 25) 29 «0. 15) «0. 15)
Chromium ~Q/L «2.0) I J «2.0) «2. 0)
Copper ~g/L (<10.0) 790(20) (<10 0)
I r on ~g/L (.065) 77000(3.9) «0 03) (0 lO)
Lead ~g/L «5.0) 950«5.0) «5.0)
ManHnese ~R/L (<10.0) 760(<10) (<10.0)
Mercury ~g/L «0.2) o. 60( <0.20) «0.2)
Nickel ~a/L 56
Zinc /Jg/L (<10.0) 81000(1220) (<10.0)
Phenol ~Q/L 56
Bar i um ~a/L 120
o.
Selenium ~g/L < 1. 0
NOTE:
() =1'iltered
aAverage concentrat ion from !ample! taken between July 1980 and October 1985.
2319168/T-RIFS.TAB/KHL
-------
TABLE 3
PRELIMINARY RISK ASSESSMENT
EXCESS LIFETIME CANCER RISK - WATER INGESTION
DAKHUE SANITARY LANDFILL SITE
Chemi ca I U. S. EPA Slope Factor Sourcel Highe3t EHe33
Carcinogen (kg-day/mg) Detected Lifetime
Classi [ication Concentrat ion Cancer
~g/L Risk
Benzene A 0 029 IRIS 7 6E-06
Carbon tetrachloride B2 O. 13 IRIS 1.6 6E-06
Chloroform B2 0.0061 IRIS 3. 2 6E-07
1. 4.0ichlorobenzene B2 O. 024 HEAST 21 IE - OS
1.I-Oichloroethane B2 0.091 HEAST 40 1 E .04
1.2.Dichloroethane B2 0.091 I R IS 63 2E.05
1.I.Dichloroethene C O. 6 IRIS 1. 5 3E-05
1.2-0ichloropropane B2 O. 068 HEAST 6. 9 IE-OS
Methylene chloride B2 0.0075 IRIS 61 IE. OS
Tetrachloroethene B2 O. OS I HEAST 210 3E.04
1.1. 2-Trichloroethane C O. OS 7 IRIS 19 3E-05
Trichloroethane B2 0.011 IRIS 60 2E.05
Sum 0 f R i s k s 6£.04
I Exposure Assump t ions I
Exposure Se t t i ng Residential
Daily Water Intake (L/day) 2
Body Weiaht (ka) 70
Number of dap/year exposed 365
Numb er 0 I year3 exposed 70
Averaging time: II let iml (yr3) 70
Li let ime average wat er intake (L/kg body O. 029
weight per day)
ISource3 01 RIDs:
IRIS. Integratld Ri3k I n lor ma t I on S 13 t em. U. S. EPA 1990.
HEAST . Health Ellect3 A33e33ment Summary Table3. U. S. EPA 1989.
2319168/T-RIFS.TAB/KML
-------
TABLE 4
PRELIMINARY RISK ASSESSMENT
NONCARCINOGENIC HEALTH RISK EVALUATION - WATER INGESTION
DAKHUE SANITARY LANDFILL SITE
Chemical Reference sourcel Concent rat i on Oa i I Y Hazard
Oose (RfO) Ilg/L Inlake Quo tie n t
mg/kg.day (0 I) Ol/RIO
mg/kg-day
Carbon tetrachloride 0 0007 IRIS 1.6 0.00005 0.066
Chlorobenzene 0.03 HEAST 27 . O. OOOg 0.026
Chloroform 0.01 I R I S 3. 2 0.0001 0.009
1.\.Oichloroelhane O. 009 I R I S 40 O. 0011 O. 127
1. I.Dichloroethene O. 009 IRIS 1. 5 O. 00004 0.005
Methylene chloride O. 06 I R I S 61 0.0017 O. 029
Toluene O. 3 I R I S 8. 4 O. 0002 0.001
\,1. 2. 2.Tetrachloroethene 0.0 l IRIS 210 o. 0060 0.600
1.1.1.Trichloroethane 0.09 IRIS 50 0.0014 0.016
1.1. 2-Trichloroethane 0.004 IRIS 19 0.0005 O. 136
Xylenes 2 IRIS 8.9 O. 0003 0.0001
Hazard Index (Sum of Ol/RID) 1. 013
I EXDosure Assumptions \
Exposure Set t i ng Residential
Receptor Adu I t
Water Intake (L/day) 2
80d'y We i ah t (ka) 70
ISources of RIDs:
I R IS, Integrated Risk Information System. U. S. EPA 1990.
HEAST - Health Eflects Assessment Summary Tables. U. S. EPA 1989.
2319168/T-RIFS.TAB/KML
-------
'fABLE 5
PRELIMINARY RISK ASSESSMENT
NONCARCINOGENIC HEALTH RISK EVALUATION - WATER INGESTION
DAKHUE SANITARY LANDFILL SITE
Chemical Reference Sourcel Concentrat ion 0 a i I Y Haz a r d
Dose (RID) ~g/L Inlake Quotient
mg/kg.day (D I) DJ/RID
mg/kg.day
Carbon tetrachloride 0.0007 I R IS 1.6 o. 00005 o. 066
Chlorobenzene o. 03 HEAST 27 o. 0008 o. 026
Chloroform 0.01 IRIS 3. 2 0.0001 0.009
1,I.Dichloroethane o. 009 IRIS 40 O. 0011 o. 127
I.l.Oichloroethene O. 009 IRIS I. 5 o. 00004 O. 005
Methylene chloride o. 06 I R' S 61 0.0017 o. 029
Toluene o. 3 I R I S 8. 4 O. 0002 0.001
1,1. 2, 2.Tetrachloroethene o. 01 I R I S 210 O. 0060 0 600
1.1.1.Trichloroethane O. 09 IRIS 50 O.OOH 0 016
1.1. 2.Trichloroeth.ne O. 004 IRIS 19 0.0005 o. ! 36
Xylene3 2 IRIS 8. 9 0.0003 O. 0001
Hazard Indu (Sum of Df/RfD) I. 013
I Exp03ure Assumption3 I
Exposure Se t t i ng Residential
Receptor Adu It
Water Intake (L/day) 2
Body WeiQht IkQ) 70
ISource3 01 R 103:
I R IS. Integrated Ri3k In 1 a rma t ion S1$ t em. u. S. EPA 1990.
HEAST . Health Effects Assessment Surrmary Tab I es. u. S. EPA 1989.
2319168/T-RIFS.TAB/KML
-------
TABLE 6
Di\mJE ~ IAN[FllL
~1~
AI.1I'ERNATIVE 1 - NO AcrION
description: the No Action alternative consists of leavin; the present COIJer
in place an:l fencin; the site to Eilirize :fut1Jre access.
Asse.sSInent:
overall Protection of Human health aro the Environment
* Not protective of the environment. ecntami.nants will continue to
leach into gra.m::1 water aro surface water.
* Potential tut:ure iIIpact on existin; receptors.
* Definite:i.11"pact to human health if future residential develcprent take
place d~client of site.
Compliance with ARARs:
* roes not CCIt1ply with state or Federal lardfill closure regulations.
Lo~-Term Effectiveness: .
* wastes remain on-site.
* Present larxifill COIJer is inadequate to prevent contaminant transp:)rt
to groun:1 water.
* Future impacts on grourrl water quality are likely.
Reduction of Toxicity, Mobility, or Volurre:
* Not applicable because no treatment is involved.
short-Term Effectiveness:
* Not awlicable because ,no remedial construction is .included.
Implernentabili ty:
* Technical feasibility not awlicable because no remedial construction
is .included.
* Not administratively feasible. No action inconsistent with state arrl
federal larxifill closure guidelines.
* Availability of services aro materials not awlicable because no
remedial construction is .included.
Cost :
*
*
Capital COst: $ 0
Annual Maintenance aro 1-bnitorin; Cost: $ 0
state Ac:ceptance:
* Not applicable because this is a State-lead site.
eamnunity Ac:ceptance:
* No action is likely to be ~.
-------
TABLE 7
J:ll\FBJE ~ IANIFllL
~ 2 ANALYSIS
ALTERNATIVE 2 - MINNESCJrA mI.ES FOR INTERIM KJNICIPAL IANDFilL WITH ClAY
BARRll:R lAYER
Description: '!he Alternative 2 cover system consists of gradin:3' an:j soil fill
to constJ:Uct a falrdation layer with mi.ninJ..Im 3 percent slq:e, a gas control
layer of 6 inches of san::l, a barrier layer of 24 :in::hes of clay, an:j a 24 inch
vegetated CXNer layer, ioclu::iin; a 6 inch drainage layer.
Assessment:
'Overall Protection of Hurran Health an:j the Envirornnent
* Protective. Allows ~ 3.2 percent of surface precipitation to
infiltrate the larrlfill. Sane lea.c:hin:3" of contaminants into grourrl
water an:j surface water.
OJrrpliance with ARARs:
* Carplies with State closure regulations for a municipal solid waste
facility.
* Canplies with ARAR of at least 90% rejection or contairnrent of surface
precipitation.
Lon;J-Term Effectiveness:
* wastes remain on-site.
* caver system allows percolation of 3.2 percent of surface
precipitation.
* '!he lOn;J-tenn adequacy of lan:j disposal is ~.
* M:inina1 potential for barrier layer failure due to differential
settlin; of larrlfill contents.
* '!he minimal thickness. (24") of the cover soil makes the clay barrier
susceptible to damage by bw:'rg.¥in; animals, shallow to deep rooted
vegetation an:j erosion, with a subsequent decrease in effectiveness
an:j possible increase in O&M.
* Very susceptible to frost damage an:j significant decrease in
effectiveness.
* lack of drainage can destroy vegetation increasin; percolation arrl
lead1a.te prcx:hlction (lower effectiveness) .
* lack of drainage can increase slcpe instability of the CXNer soil.
Reduction of Toxicity, Mobility, or Volume:
* Not ~licable because no treatment. is involved
Short-Term Effectiveness:
* Minimal risk to the CCItIItUJIlity durin; cover system construction.
* Potential risk to v.'Orkers durin; construction due to emissions of
volatile organic carpourx:1s or methane. Requires air m:>nitorin; arrl
possible respiratory protection.
* Possible envirornnental impacts due to particulate emissions.
Requires dust control durin; remedial construction.
* :En:3"ineerin; arrl construction will require 1 to 2 years. Protection
-------
. , .
against infiltration will be achieved :imnediate.ly, althaJgh the effect
on grc.urrl water quality will not be d:::served until a later time when
pera:>lation of previous infiltration is c:arplete.
Implementabili ty:
* Technically feasible.
constIuction .
* Administratively feasible. Requires agercy coordination to assess the
afPI'opriateness of a m.micipal waste closure action.
* Services an:i mterials are available.
Minimal technical problems durirq design am.
Cost :
*
*
capital Cost: $7,600,000
Annual Maintenance an:i !wbnitorirq Cost: $53,000
State A£;x::eptance:
* Not applicable because this is a State-lead site.
COmmunity A£;x::eptance:
* All containment alternatives may be opposed.
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TABLE 8
J:WlBJE ~ .!:AND?IIL
~ 3 ANAUSIS
ALTERNATIvE 2 - MINNESOrA mr.rn FOR ACTIVE MJNICIPAL lANDFILL, CIM BARRIER
IAYER
DescriptiO!}: '!he Alternative 3 CCNer system CXJnSists of grad.in; arrl soil fill
to construct a fa.tn:1ation layer with m.inim.nn 3 percent slcpe, a gas control
layer of 6 inches of sarrl, a barrier layer of 24 inches of clay, a 12 inch
sarrl lateral drainage layer, and an 36 inch vegetated CCNer layer.
As~c::T'n€'J1t :
OVerall Protection of Hunan Health arrl the Environment
* Protective allCMS aro.rt 3.0 percent of surface precipitation to
infiltrate lan:lfill. Sare leach:iJ-q of contaminants into grourrl water
arrl surface water.
Caripliance with ARARs:
* Carplies with State closure regulations for a nu.micipal solid waste
facility.
Lo~-Tenn Effectiveness:
* wastes remain on-site.
* Cover system allCMS percolation of 3.0 percent of surface
precipitation. .
* 'Ihe lo~-te.nn adeq:uacy of larrl disposal is unknown.
* Mini.ma1 potential for barrier layer failure <;iue to differential
settl~ of lan:lfill contents. .
* J3urr0w~ animals arrl vegetation can distu:rb ~ thickness of
barrier withCRlt significant reduction in effectiveness arrl a likely
reduction in O&M costs. /
* Lateral drainage layer arrl thickness of cover above layer barrier
minimizes potential frost damage.
Reduction of Toxicity, Mcbility, or Voltnne:
* Not applicable because no treatment is involved.
Short..JI'eIm Effectiveness:
* Mi.nima1 risk to the CCITU'!UJ11.i ty dur~ o::Ner system constzuction.
* Potential risk to workers dur~ constzuction due to emissions of
volatile organic cx:rrpourrls or n-ethane. Requires air monitor~ and
possible respiratory. protection.
* Possible erwiIonmental i!rpacts due to particulate emissions. Requires
dust control dur~ remedial constzuction.
* En;Jineer~ and construction will require 1 to 2 years. Protection
against infiltration will be achieved immediately, although the effect
on groon:i water quality will not be observed \D1til a later tine when
percolation of previ"'-lS infiltration is cc:atplete.
Implerentabili ty:
. * Technically feasible. Mini1ra.1 technical problems durin;J design and
-------
*
construction.
Administratively feasible. Requires agency COOrdination to n~=<;s the
awropriateness of a m.micipal waste closure action.
Sel:vices arrl materials are available.
*
Cost:
*
*
Capital Cost: $9,800,000
Annual K3.intenan::e arrl ?-bni tori.n; Cost: $54, 000
State Acx::ept:.ance:
* Not awlicable because this is a State-lead site.
Ccmrnuni ty Acx::ept:.ance:
* All contaiment al ternati yes may be CJf"POSed.
-------
TABLE 9
mm:m SANITARY' IANI:FIIL
~ 4 NW::iSIS
AI.:I'ERNATIVE 4 - RrnA OJVER SYSTEM FDR HAZARIX:US WASTE CLC6URE
Description: '!he Alternative 4 caver system CX){1Sists of grad.in; an::l soil fill
to construct a foordation layer with m:inimJm 3 percent slq:>e, a gas control
layer of 6 inches of san::l, a barrier layer of 30 mil thickness high densib.l
p:>lyethylene liner an::l 24 i.rd1es of clay, a 12 inch san::l lateral drainage
layer, an::i a 48 inch vegetated caver layer.
Assessment:
. .
oVerall Protection of Human Health an::i the Enviroranent
* Protective. Virtually eli:m.ir.ates leachate generation due to
infiltration of precipitation.
Ccirpliance with ARARs:
* Carrpliance with RrnA closure regulations an::i design guidance documents
for a hazardous waste Cl:Ner system.
IDn:J-Term Effectiveness:
* Wastes remain on-site.
* CcNer system virtually eli:m.ir.ates percolation of surface
precipitation, initial efficiency of 99.6 percent.
* . 'Ihe lOn:J-tenTl adequacy of lan::l d.i..sFOSa1 is unknown.
* synthetic membrane an::l lateral drainage layer minimizes
to the clay barrier.
* MiniIna1. potential for Cl:Ner system failure.
frost dalrage
Reduction of Toxicity, Mobility, or Volume:
* Not applicable because 00 treatment is involved.
Short-Term Effectiveness:
* MiniIna1. risk to the cannnmi ty during caver system construction.
* Potential risk to workers during construction due to emissions of
volatile organic carpounis or methane. Requires air ItDni toring an::l
possible respiratory protection.
* Possible environmental impacts due to particulate emissions. Requires
dust control durirg remedial construction.
* ~ineering ani construction will require 1 to 2 years. Protection
against infiltration will be achieved immediately, although the effect
on groon:i water quality will not be observed tmtil a later t:i1ne when
percolation of previcus infiltration is c::arplete.
Implementabili ty:
* Technically feasible. Mi.nima1 ted1nical prd:>lems ciurirg design an::l
construction, although ItDre diffio..1J.t than other CCNer designs.
* Administratively feasible. Requires agency coordination to assess the
awropriateness of a hazardous waste closure action.
* Services an::l materials are available. High costs for clay t.ranst:ort
may cause bentonite/soil mixture to be a cost-effective alternative.
-------
O:st:
*
*
Capital O:st: $13,000,000
AnrnJal Haintenance arrl l-bnitor~ O:st: $54,000
StateAcoeptance: .
* Not awlicable because this is a State-lead site.
Cormmmity Acoeptance:
* All contairunent alternatives may be ~, J:ut possible lesser
q:p::si tion due to the secon:i barrier layer provide:i.
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APPENDIX B
-------
********** DRAFT **********
OPERATION AND MAINTENANCE COST DEVELOPMENT
SITE NAME: DAKHUE SANITARY LANDFILL
REGION: 05
OPERABLE UNIT: DAKHUE SANITARY LANDFILL - SOU
ESTIMATED START: EARLY FY 1992
. RUN BY: TED SMITH
INDIVIDUAL TECHNOLOGY COSTS
PHONE NUMBER: 312-353-6571
---------------------------
SCENARIO: . ALTERNATIVE 4. RCRA CAP
SITE ACCESS RESTRICTIONS
MULTILAYERED RCRA CAP
SUBTOTAL
SITE COSTS
----------
SITE PREPARATION
GENERAL CONDITIONS
------------------
INSURANCE AND PERMIT RENEWAL
SUBTOTAL
INDIRECT COSTS
--------------
ADMINISTRATION
CONTINGENCIES
TOTAL 0 & M DAKHUE SANITARY LANDFILL - SOU
'0
TOTAL SITE 0 & M COST
DATE:
TIME:
11/21/90
16:25:44
o
36,000
36,000
o
5,400
41,000
6,200
6,200
53,000
53,000
-------
********** DRAFT **********
CAPITAL COST DEVELOPMENT
SITE NAME: DAKHuE SANITARY LANDFILL
REGION: 05
OPERABLE UNIT: DAKHUE SANITARY LANDFILL - SOU
ESTIMATED START: EARLy FY 1992
RUN BY: TED., SMITH
INDIVIDUAL TECHNOLOGY COSTS
PHONE NUMBER: 312-353-6571
---------------------------
SCENARIO: ALTERNATIVE 4. RCRA CAP
.SITE ACCESS RESTRICTIONS
MULT I LAYERED RCRA CAP
SUBTOTAL
SITE COSTS
----------
SITE PREPARATION
SITE ADMINISTRATION
GENERAL CONDITIONS
------------------
START-UP COSTS
CONSTRUCTION SUBTOTAL
BID CONTINGENCIES
SCOPE CONTINGENCIES
CONSTRUCTION TOTAL
PERMITTING AND LEGAL COSTS
SERVICES DURING CONSTRUCTION
TOTAL CAPITAL DA~ SANITARY LANDFILL - SOU
TOTAL SITE CAPITAL COST
DATE:
TIME:
11/21/90
16:25:27 ,
95,000
8,100.000
8,200,000
o
750.000
o
9,000,000
1,800.000
1.200,000
12,000,000
410,000 '
820.000
13.000.000
13.000,000
-------
********** DRAFT **********
OPERATION AND MAINTENANCE COST DEVELOPMENT
SITE NAME: DAKHUE SANITARY LANDFILL
REGION: 05
OPERABLE UNIT: DAKHUE SANITARY LANDFILL - SOU
ESTIMATED START: EARLY FY 1992
RUN BY: TED SMITH
INDIVIDUAL TECHNOLOGY COSTS
PHONE NUMBER: 312-353-6571
---------------------------
SCENARIO: ALTERNATIVE 3. "D+" CAP
MULTI LAYERED RCRA CAP
SITE ACCESS RESTRICTIONS
SUBTOTAL
SITE COSTS
----------
SITE PREPARATION
GENERAL CONDITIONS
------------------
INSURANCE AND PERMIT RENEWAL
SUBTOTAL
INDIRECT COSTS
--------------
ADMINISTRATION
CONT1NGENCIES
TOTAL 0 & M DAKHUE SANITARY LANDFILL - SOU
TOTAL SITE 0 & M COST
DATE:
TIME:
-
11/21/90
16:28:27
36,000
o
.36 ,000
o
5,400
41,000
6.200
6.200
53,000
53.000
-------
********** DRAFT **********
CAPITAL COST DEVELOPMENT
SITE NAME: DAYJIDE SANITARY LANDFILL
REGION: 05
OPERABLE UNIT: DAKHUE SANITARY LANDFILL - SOU
ESTIMATED START: EARLY FY 1992
RUN BY: TED SMITH
INDIVIDUAL TECHNOLOGY COSTS
PHONE NUMBER: 312-353-6571
---------------------------
SCENARIO: ALTERNATIVE 3, "D+" CAP
MULTILAYERED RCRA CAP
SITE ACCESS RESTRICTIONS
SUBTOTAL
SITE COSTS
----------
SITE PREPARATION
SITE ADMINISTRATION
GENERAL CONDITIONS
------------------
START-UP COSTS'
CONSTRUCTION SUBTOTAL
BID CONTINGENCIES
SCOPE CONTINGENCIES'
CONSTRUCTION TOTAL
PERMITTING AND LEGAL COSTS
SERVICES DURING CONSTRUCTION
TOTAL CAPITAL D~KHUE SANITARY LANDFILL - SOU
TOTAL SITE CAPITAL COST
DATE:
TItlE:
11/21/90
16:27:49
6,000,000
95,000
6,100,000
o
620,000
o
6,700,000
1,300,000
860,000
8,900,000
300,000
610,000
9.800,000
9,800,000
-------
********** DRAFT **********
OPERATION AND MAINTENANCE COST DEVELOPMENT
SITE NAME: DAKHUE SANITARY LANDFILL
REGION: 05
OPERAB1E UNIT: DAKHUE SANITARY LANDFILL - SOU
ESTIMATED START: EARLY FY 1992
RUN BY: TED SMITH
INDIVIDUAL TECHNOLOGY COSTS
PHONE NUMBER: 312-353-6571
---------------------------
SCENARIO: ALTERNATIVE 2. CLAY CAP
SITE ACCESS RESTRICTIONS
MULTILAYERED RCRA CAP
SUBTOTAL
SITE COSTS
----------
SITE PREPARATION
GENERAL CONDITIONS
------------------
INSURANCE AND PERMIT RENEWAL
SUBTOTAL
INDIRECT COSTS
--------------
ADMINISTRATION
CONTINGENCIES
TOTAL 0 & M DAKHUE SANITARY LANDFILL - SOU
-.
TOTAL SITE 0 & M COST
-
DATE:
TIME:
11/21/90
16:23:00
o
36,000
36,000
o
5.400
41, 000
6.200
6,200
53,000
53,000
i
f
!
-------
********** DRAFT **********
CAPITAL COST DEVELOPMENT
SITE NAME: DAKHUE SANITARY LANDFILL
REGION: 05
OPERABLE UNIT: DAKHUE SANITARY LANDFILL - SOU
ESTIMATED START: EARLY FY 1992
RUN BY: TED SMITH
INDIVIDUAL TECHNOLOGY COSTS
PHONE NUMBER: 312-353-6571
---------------------------
SCENARIO: ALTERNATIVE 2. CLAY CAP
SITE ACCESS RESTRICTIONS
MULT I LAYERED RCRA CAP
SUBTOTAL
SITE COSTS
----------
SITE PREPARATION
SITE ADMINISTRATION
GENERAL CONDITIONS
------------------
START-UP COSTS
CONSTRUCTION SUBTOTAL
BID CONTINGENCIES
SCOPE CONTINGENCIES
CONSTRUCTION TOTAL
PERMITTING AND LEGAL COSTS
SERVICES DURING CONSTRUCTION
TOTAL CAPITAL DAKHUE SANITARY LANDFILL - SOU
TOTAL SITE CAPITAL COST
DATE:
TIME:
11/21/90
16:21:56
95.000
4.500,000
4,600,000
o
570,000
o
5,200,000
1, 000 t 000
660,000
6,900,000
230.000
460,000
7,600.000
7,600,000
-------
'.
,
",
,'......
RESPONSIVENESS SUMMARY
Source-Control Feasibility Study,
Dakhue Landfill
This community responsiveness summary has been developed to document
community involvement and concerns during the source-control operable
unit phase of the project and to respond to public comments received during
the public comment period. Section vn in the Record of Decision is a
summary of the community relations activities conducted by the Minnesota
Pollution Control Agency (MPCA) since the Remedial Investigation and
Feasibility Study was funded under a cooperative agreement with the U.S. .
Environmental Protection Agency (EPA).
A. OVERVIEW
The recommended alternative for a cover at the Dakhue site was announced
to the community through a legal notice in the local newspaper of record and
a fact sheet mailed to all interested parties. The recommended alternative
consists of a three-percent slope, a gas control layer, a two-foot barrier layer of
clay, a sand drainage layer, and a top cover of four feet of soil and vegetation.
A number of public comments were received during the public meeting on
the feasibility study; no other comments were received during the comment
period. The MPCA's response to those comments is contained in a later
section of this responsiveness summary. The summary consists of the
following sections:
. Background of Community Involvement
. Summary of Comments Received and Agency Responses
. Remedial Design/Remedial Action Concerns
B. BACKGROUND OF COMMUNITY INVOLVEMENT
As detailed in the Community Relations Plan for this site, community feeling
was strongest during the time the landfill was still operating, due to concerns
with heavy truck traffic, improper daily cover, and blowing litter. Since the
ground-water contamination problem was discovered, residents near the
landfill have been concerned about the possibility of contamination spreading
to their wells; the MPCA will continue to address those concerns during the
course of the Remedial Investigation for the ground-water migration
operable unit.
-------
",1
The MPCA is the community relations lead for this project, and has
conducted all activities to this point. In April of 1991, residents were mailed
an invitation to a public meeting to discuss the feasibility study and proposed
plan, along with a fact sheet describing the alternatives. The meeting and
proposed plan, with public comment period, were noticed officially in the
local newspaper of record. The public meeting was held on April 30, 1991.
This commenced a 30-day public comment period, which closed May 30.1991.
Fact sheets were also available at the meeting.
C. SUMMARY OF COMMENTS RECEIVED AND MPCA RESPONSES
Comments received during the public comment period on the Source
Control Feasibility Study and Proposed Plan are summarized below:
Comment: Citizen expressed concern about whether there will be sufficient
monitoring for methane (odors and health risks), and asked if the MPCA had
considered flaring off methane.
MPCA response: Methane is an odorless, non-toxic gas. The risk from
methane is that it is explosive in confined spaces (such as basements) at
concentrations of 5% methane by volume. Methane is a typical byproduct of
decomposition in landfills. The methane generated in the Dakhue landfill
will be passively vented through the gas-control layer to the atmosphere.
Treatment options for air emissions from gas vents ~uilt into the cover will
be considered after construction of the final cover. The site will be inspected
on an annual basis, including monitoring to determine if ambient methane
concentrations call for treatment. Flaring would be one of the options
considered.
Comment: A resident asked if the site would be restored to visually
acceptable standards after construction.
MPCA response: The final design of the landfill surface will be determined
during remedial design. Contour slopes on the landfill will be greater than 3
percent on the fill area and less than 20 percent on the side slopes. The
landfill surface will be seeded wi th shallow-rooting perennial grasses. The
final disposition of on-site fill "borrow" areas will be determined during site
design. Every effort will be made to restore the site to a visually acceptable
standard. .
Comment: A resident read a four-page statement containing a number of
concerns about the landfill and the remediation project. Some of them relate
to the remedial investigation currently underway as part of the ground-water
migration operable unit; they are not addressed here, because they are not
-------
relevant to source control. Those comments that are relevant to source
control are summarized below. The statement:
./
- expressed a strong desire that the wastes in the landfill be excavated and
removed entirely.
MPCA response: This alternative was addressed in the initial screenh1.g of
possible alternatives in the feasibility study. Unless there is evidence of
hazardous materials in known, discreet locations in a landfill, exhumation of
the contents is impracticable. There is no such evidence at the Da~\1Ue
landfill. If wastes were to be excavated, they would need to be disposed of
either on-site or off-site. Both options were eliminated because their
estimated costs of $300 million did not meet"the cost effectiveness criteria.
- alleged that wastes are in contact with the water table, thereby making a
cover system irrelevant for purposes of source control.
MPCA response: The MPCA has no evidence to support this allegation.
Current data indicates the water table beneath the landfill site is at least 65 feet
below the estimated bottom of the waste-filled portion of the landfill. Prior to
1971 the land within the site boundary was primarily undeveloped, and the
MPCA has found no records of quarrying or other activities that would have
resulted in a hole deep enough to have allowed direct contact with the water
table.
- alleged that significant amounts of industrial waste have been disposed
of at the the site and that the MPCA has not sufficiently investigated waste
composition in the landfill to determine if it contains significant quantities of
hazardous wastes.
MPCA response: The MPCA is aware that some industrial wastes were
deposited at the site. However, the majority of the waste carne from mixed
municipal sources. The MPCA sent 280 letters to potentially responsible
parties requiring them to provide information about disposal at the landfill.
The responses indicate that the wastes contributed by most companies could
not be categorized as hazardous wastes. .
- expressed concern that the MPCA will not conduct an adequate search
for potentially responsible parties and that no one will be held accountable for
the ground-water contamination.
MPCA response: The MPCA currently is conducting a search for potentially
responsible parties (PRPs) using many information sources, including landfill
records, MPCA co-disposal and hazardous waste disclosure records, hazardous
waste enforcement files, Dakota County co-disposal records, and interviews
with the landfill operator, employees, refuse haulers, and neighbors. In
-------
~..-
addition, the Yellow Pages were used to determine additional businesses in
the geographical area that may have hauled wastes to the landfill. By law,
both the state and federal Superfund programs must attempt to recover costs
from responsible parties. This process is moving forward concurrently with
cleanup efforts.
- alleged that ground water testing has been "sporadic, infrequent, limited
in parameters, and so unscientific as to render it almost meaningless, with no
residential well testing in the past 18 months."
MPCA response: The ground water sampling conducted in relation to this
site has focused on volatile organic compounds (VOCs). VOCs are a class of
chemicals that are common constituents of household and industrial
products. VOCs are better indicators of more general ground-water pollution
than previously used parameters such as chloride, nitrate, etc. This list of
parameters was compiled by the Minnesota Department of Health (MDH) as
representative of potential contamination that might be expected to occur at a
landfill, based on a 1986 MPCA study of 61 landfills across the state. Ground
water sampling at the Dakhue landfill analyzes for a total of 68 VOCs.
On February 4, 1991, seven residential wells adjacent to the landfill, including
the commenter's, were sampled for water-quality analysis. Results were
mailed to all parties involved on March 22. Previously, residential wells
were sampled in May, October, July, and December of 1989. The May samples,
collected by Dakota County, were analyzed by Minnesota Valley Testing
Laboratories (MVTL). The October and December rounds were collected by
Dakota County and analyzed by MDH. The July round was collected by the
MPCA and analyzed by MDH. Only the May round detected any VOCs. The
quality assurance/quality control data for this sampling round was not
available for review, and the MPCA suspects lab contamination as the cause
of VOC detection. This sampling is extremely sensitive and vulnerable to lab
contamination, and interpretation of results must be substantiated by
continued testing. The results of the four most recent rounds of sampling
indicate that residential wells adjacent to the site have not been impacted
thus far by the landfill. .
- raises the issue of compensating landowners on whose property
monitoring wells have been installed.
MPCA response: Minnesota Statutes Chapter 115B (the state Superfund law)
authorizes the MPCA to enter upon any property, public or private, for the
purpose of taking any action authorized by the statute, including obtaining
information, conducting surveys or investigations, and taking removal or
remedial actions. The MPCA is not authorized to pay compensation to
property owners for remedial investigation and does not budget for such
compensation.
-------
",.
. ,l
D. REMEDIAL DESIGN /REMEDIAL ACTION CONCERNS
Residents have voiced several additional concerns during the source-control
feasibil~ty study that should be kept in mind during design and construction.
These concerns include: .
1. Making sure that the site is restored to an aesthetically acceptable standard,
particularly in the case of any large borrow pits that may result from filling
and grading.
2. That any further erosion of the landfill surface and sides, with resulting
siltation onto neighboring fields, be permanently prevented.
3. That' access to the site be tightly and permanently restricted to prevent
illegal dumping from occurring on the site. Nearby residents have
complained of dumping occurring during the period of the feasibility study,
and the gate that had been installed across the site access road has been
smashed on at .least one occasion.
-------
Administrative Record for the Dakhue Sanitary Landfill
1.
Dakhue Sanitary Landfill Evaluation Report, November 1987, Bruce A. Liesch
Associates Inc.
2.
Remedial Investigation/Feasibility Study W:>rk Plan for the Migration Control
Operable Unit, Approved Septenber 1990, Barr Engineering Canpany.
3.
Focused Feasibility Study for the Source Control Operable Unit, Approved
March 1991, MPCAIEPA.
.4.
5.
Proposed Plan for the Source Control Operable Unit, April 1991, MPCA.
Preliminary Health Assessment for the Dakhue Sanitary Landfill Prepared by
the Minnesota Health Department for Agency for 'Ibxic Substances and Disease
Registry, June 1991.
6.
Record of Decision for the Source Control Operable Unit, Approved June 1991,
MPCAIEPA.
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