EPA/ROD/R05-95/294
1995
EPA Superfund
Record of Decision:
SAUK COUNTY LANDFILL
EPA ID: WID980610141
OU01
EXCELSIOR, WI
09/28/1995
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RECORD OF DECISION
REMEDIAL ACTION FOR THE GROUNDWATER OPERABLE UNIT
Site Name and Location
Sauk County Landfill
The Sauk County landfill is located in the Town of Excelsior, Sauk County,
Wisconsin (approximately 6 miles east of the City of Reedsburg and
approximately 9 miles west and north of the City of Baraboo) , SE 1/4 of
Section 15, Township 12 North, Range 5 East.
Statement of Basis and Purpose
This decision document represents the selected groundwater remedial action for
the Sauk County Landfill in the Town of Excelsior, Sauk County, Wisconsin,
developed in accordance with CERCLA, as amended by SARA, and to the extent
practicable, the National Contingency Plan. The attached Summary of Remedial
Alternatives identifies the information contained in the administrative record
for this site upon which the selection of the remedial action is based.
The selected groundwater remedy is Alternative A, the No-Action Alternative.
Under this alternative, monitoring of groundwater quality over time will take
place. The WDNR considers this a no further action ROD. Twelve (12) on-site
groundwater monitoring wells and six (6) off-site private water supply wells
will be sampled for volatile organic compounds (VOCs) on a semi-annual basis
to determine changes in groundwater quality with time. If the VOC
concentrations in the groundwater increase in violation of NR 140, Wis. Adm.
Code, then additional source control measures will be taken, including the
installation of a composite landfill cover. Details on the potential source
control actions are listed in the source control Record of Decision for this
site. This groundwater operable unit is the second of two operable units. The
record of decision for the first operable unit, source control, was issued in
March, 1994.
The principle threat of groundwater contaminants are met through the
previously installed source control measures, and the natural attenuation,
degradation and dilution of contaminants in groundwater.
This groundwater remedy is protective of human health and the environment,
complies with Federal and State requirements that are legally applicable or
relevant and appropriate requirements ("ARARs") for this action, and is cost
effective. Because this remedy will result in hazardous substances remaining
on-site, a review will be conducted to ensure that the remedy continues to
provide adequate protection of human health and the environment within 5 years
after the commencement of this remedial action.
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The remedy utilizes permanent solutions to the extent practicable. This remedy
does not satisfy the statutory preference for treatment as a principle element
of the remedy. Natural attenuation, degradation and dilution of groundwater
contaminants will take only slightly longer than an active treatment system
and will cost less.
A review of the remedy and groundwater quality will be conducted every five
years. This review shall concentrate on whether the standards in NR 140, Wis.
Adm. Code are being met.
9-
Meyer, SeereGcry Date
Wisconsin Department of Natural
Resources
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SUMMARY OF REMEDIAL ALTERNATIVES SELECTION
GROUNDWATER REMEDY
SAUK COUNTY LANDFILL
The following summarizes the information contained in the administrative
record for the Sauk County Landfill site. The selected groundwater remedy is
based upon the information contained in the site's administrative record.
I. SITE NAME, LOCATION AND DESCRIPTION
The Sauk County Landfill was listed on the National Priorities List (NPL) by
the U.S. Environmental Protection Agency (EPA) in October of 1989. This site
does not include the active Sauk County landfill which is located a few
hundred feet north of the closed Sauk County Landfill.
The Sauk County Landfill is located in the northeastern part of the county
between Reedsburg and Baraboo, south of Hwy 33. The landfill is 14 acres in
size and is part of a 320 acre parcel containing both the closed and active
landfills in the Southeast 1/4 of Section 15, Township 12 North, Range 5 East,
Town of Excelsior, Sauk County, Wisconsin. The location is depicted on Map 1.
The landfill and property boundary are fenced. Vehicle access is limited by a
gate across the road entering the landfill property.
The Sauk County landfill accepted municipal and industrial waste from Sauk
County between the years 1973 and 1983. The site was designed as a natural
attenuation landfill. This means it has no liner or leachate collection
system. It has a waste volume of about 750,000 cubic yards.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
Sauk County operated this landfill between 1973 and 1983. During operations,
the site accepted municipal, commercial and industrial wastes, including over
200,000 tons of foundry sand. The foundry sand was used primarily in berms on
the edge of the refuse. The site was closed in 1981 with a cover system
consisting of 2' of clay on the landfill surface, 1' of clay on the sidewalls
and 611 of topsoil over the entire site. The topsoil was vegetated. The site
has been maintained by Sauk County since closure.
After reviewing groundwater quality data from this landfill, the WDNR
recommended to EPA that the site be included on the National Priorities List
(NPL). The site was listed on the NPL in 1989. In September, 1991, Sauk County
entered into a contract with WDNR to perform a remedial investigation and
feasibility study ("RI/FS") pursuant to s. 144.442, Wisconsin Statutes and the
Comprehensive Response, Compensation and Liability Act ("CERCLA"). Under terms
of the contract, Sauk County also agreed to complete a Source Control Operable
Unit. WDNR issued a source control record of decision (ROD) for this site in
March, 1994.
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SAUKCQUOTY LANDFILL
REEDSBURG
BARABQO
MADISON
SUE LOCATION MAP
REEDSBURG
SAUK COUNTY LANDFILL
BARABOO'
Not to Scan
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The RI was completed and submitted to WDNR on April 28, 1994. The FS for
groundwater remediation was submitted to WDNR on January 4, 1995.
Ill. HIGHLIGHTS OF THE COMMUNITY PARTICIPATION
An information repository has been established at the Reedsburg Public
Library, 345 Vine Street, Reedsburg, Wisconsin. The administrative record is
made available to the public at the Baraboo Public Library, 230 Fourth Street,
Baraboo, Wisconsin.
In September, 1992 WDNR issued a Superfund Fact Sheet which provided a summary
of the site history, explained the Superfund process and delineated the
approved RI work plan. On September 29, 1992 the WDNR and the Wisconsin
Department of Health and Social Services (WDHSS) held a public informational
meeting at 7:00 p.m. in the Rock Springs Community Center. The meeting was
held to discuss the landfill and to explain the RI field work which was about
to start. Approximately 30 residents attended the meeting.
Residents living near the landfill created the Evergreen Property Owners
Association. On November 11, 1992 the Property Owners Association organized a
meeting attended by WDNR, WDHSS and Simon Hydro-Search (consultant to Sauk
County) to answer questions from residents living near the landfill.
Approximately 100 persons attended this meeting.
In March, 1993 WDNR issued a Superfund Fact Sheet containing a summary of the
RI data up to that point in time. This tact sheet contained information on:
* groundwater quality in on-site monitoring wells
* groundwater quality at houses surrounding the landfill
* preliminary results from a vegetation survey designed to detect methane
stress, and
* a timeline for installing new monitoring wells at the site.
In May, 1993 the Evergreen Property owners Association was awarded a Technical
Assistance Grant from EPA. The purpose of the grant is to allow persons
affected by Superfund sites to retain their own technical staff to explain the
Superfund process and the data generated during the RI.
In September, 1993 the WDNR issued another Superfund Fact Sheet. This fact
sheet also contained a summary of the RI data.
The Proposed Plan for the source control operable unit was made available for
public comment on September 8, 1993. Notices announcing the availability of
the proposed plan were published in the Reedsburg Time Press and the Wisconsin
State Journal on September 2, 1993. A public meeting to explain the Proposed
Plan, and to receive public comments was held on September 21, 1993.
Approximately 40 persons attended the meeting. The public comment period was
held between September 8, and November 9, 1992. Comments received from the
public and WDNR's response to those comments are included in the source
control record of decision.
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WDNR issued a proposed plan for groundwater remediation in March, 1995. The
RI/FS and proposed plan were available for public comment in the
administrative record. The public comment period ran between March 3 and April
10, 1995. WDNR was available to hold a public meeting, but didn't receive any
requests to hold such meeting. WDNR didn't receive any comments during the
public comment period.
At the time the WDNR announced the proposed plan, the WDNR failed to place an
add in the newspaper. CERCLA requires that an add be placed in the newspaper
of record when a proposed plan has been issued. To comply with CERCLA, the
WDNR placed an add in the Baraboo News Republic on June 29, 1995. The add
announced the availability of the groundwater proposed plan and opened another
public comment period running between June 29 and August 1, 1995. The WDNR
didn't receive any public comments during this second public comment period.
The public participation requirements of s. 144.442(6)(f), Wisconsin Statutes,
and the community relations requirements in the National Contingency Plan
at 40 CFR s. 300.430(f)(3) have been met in this groundwater remedy
selection process.
IV. SCOPE OF THE GROUNDWATER REMEDY
The groundwater contaminants from this landfill is volatile organic compound
(VOC) contamination. Sauk County has been measuring VOCs at various monitoring
wells since the mid 1980's. Since that time, VOC concentrations have dropped
dramatically. Plots showing the VOC concentrations over time are included, in
the source control ROD. Should VOC concentrations continue decreasing at the
rate shown in the past several years, all contaminants should be below their
respective preventive action limits within the next couple of years.
Preventive action limits (PALs) are the clean up standards for contaminants in
groundwater. PALs are listed in NR 140, Wis. Adm. Code.
Since groundwater quality is improving, active groundwater remedial actions
are not considered necessary for this site. The No Action alternative includes
a groundwater monitoring plan that was approved as part of the source control
remedy. Under the plan, twelve (12) on-site monitoring wells and six (6)
off-site private water supply wells will be monitored for VOCs. Sampling of
the wells will take place in April and October of each year. After five (5)
years of sampling results are available, the data will be analyzed to
determine whether or not there is compliance with NR 140, Wis. Adm. Code, and
compliance with terms set forth in the source control ROD.
V. SUMMARY OF SITE CHARACTERISTICS
A. Topography
The Sauk County landfill is located along the eastern margin of the
unglaciated area. Topography in the site vicinity is gently sloping to
somewhat hilly. The landfill is located in an east-west trending valley
bounded to the north and south by sandstone bedrock ridges. Elevations on the
ridges are approximately 1200 feet above mean sea level. The valley is gently
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sloping to the west with elevations near the fill ranging from 1010 to 960
msl.
B. Geology/Hydrogeology
The geology near the landfill consists of approximately 50 feet of
unconsolidated material, primarily sand with some silt and gravel layers
present. The color of the sand is predominantly brownish yellow. Below the
unconsolidated material three different bedrock units were identified.
The top of the bedrock is a poorly lithified weathered sandstone. This is the
Mazomanie Formation. It is medium grained and brown to yellow in color, it
ranges in thickness from approximately 40' east of the landfill to only 5' at
the western edge of the County property.
The next bedrock unit is the Lone Rock Formation. This unit consists of
siltstone, shale and very fine grained sandstone. It ranges in thickness from
30' to over 50'. This unit acts as a semi-confining unit between the sandstone
units above and below.
Below the Lone Rock Formation is the Wonewoc Formation. It is a medium grained
sandstone that is brown, reddish brown to yellow in color. The entire
thickness of the Wonewoc was not penetrated by monitoring wells, but it is at
least 65' thick near the landfill. The Wonewoc Formation acts as a water
supply aquifer for homes located to the west of the landfill.
Within the unconsolidated deposits, shallow groundwater at or near the water
table flows west, southwest towards the Baraboo River. This upper flow system
has an average horizontal gradient of 0.015 ft/ft west of the landfill. Near
the base of the unconsolidated deposits and within the weathered sandstone
(Mazomanie Fm) groundwater also flows west, southwest with a horizontal
gradient ranging from 0.010 to 0.013 ft/ft. These groundwater flow directions
are a result of the natural slope of the upper bedrock surface.
Directly beneath the siltstone and shale semi-confining layer (Lone Rock Fm) ,
groundwater flows southeast with a gradient of 0.006 to 0.007 ft/ft. Deeper
within the Wonewoc Formation groundwater flows to the east. This is consistent
with the regional flow towards the Wisconsin River. The horizontal gradient in
the deeper Wonewoc is approximately 0.0012 ft/ft.
All vertical gradients were downward and ranged from 0.02 to 0.76 ft/ft. The
highest vertical gradient was noted to the east of the landfill where the
semi-confining layer is thickest. Thickness of the confining layer as well as
the lithology and competence of the Lone Rock Formation are likely to affect
vertical gradients.
C. Groundwater Contamination
Based upon data collected as part of the RI, a total of 18 volatile organic
compounds (VOCs) were detected in groundwater monitoring wells. The most
common VOCs detected are 1,1-DCA which was found in 13 wells and 1,1,1-TCA
which was found in 8 wells. Of the 18 VOCs detected, only two exceeded
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enforcement standards found in NR 140, Wis. Adm. Code, during sampling events
in 1993. Tetrachloroethylene (PCE) and vinyl chloride were detected in
concentrations attaining or exceeding enforcement standards. Five additional
VOCS [1,2-dichloropropane, 1,2-dichloroethane, 1,1-dichloroethane, benzene,
cis 1,2-dichloroethene] exceeded NR 140, Wis. Adm. Code preventive action
limits. Table 1, 2, 3 and 4 from the qualitative risk assessment list the
concentrations of the groundwater contaminants and compares them to
groundwater quality standards.
A total of 18 private wells surrounding the landfill have been tested for
VOCs. A home located approximately 3000 feet west-southwest of the landfill
has detected VOCs. 1,1-dichloroethane (1,1-DCA) has been detected on two
occasions and 1,1,1-trichloroethane (1,1,1-TCA) has been detected three times.
These samples were taken in 1992, 1993 and 1994. In all three sampling events,
the concentrations of these two compounds were far below their respective
drinking water standards. A second home had detections of 1,1-DCA and
1,1,1-TCA the first time it was sampled. These detections were also far below
the drinking water standards. Subsequent sampling of the well has failed to
detect any VOCS. None of the other 16 wells tested have had VOCs detected.
The groundwater monitoring plan approved under the source control remedy, and
included as part of the No Action alternative for groundwater remediation will
effectively monitor changes in groundwater quality with time.
D. Landfill Gas
Three of the gas probes and one well located within the waste had landfill gas
samples collected and analyzed for VOCs. Nineteen VOCs were detected with the
highest concentration of total VOCs occurring in the gas probe on the east
side of the landfill. The VOCs with the highest concentration (at any sampling
point) are methyl ethyl ketone, toluene, vinyl chloride, total xylenes and
1,1-DCA.
In addition, the gas probes, two wells screened within the waste, and a
background location were measured for methane, oxygen and carbon dioxide. The
background sample was not a soil gas sample, but was an ambient air sample
near the access gate to the landfill. It can only be used for comparative
purposes. All methane measurements except the background location and the gas
probe on the southern edge of the landfill indicated explosive concentrations
of methane.
The source control ROD required a landfill gas extraction and treatment
system. This system was installed during the winter of 1994-1995. Fifteen gas
wells collect gas generated within the waste and route it to a flare for
combustion.
VI. SUMMARY OF SITE RISKS
A qualitative risk assessment was completed for the Sauk County landfill
Superfund site. The purpose of the assessment was to identify human health
hazards posed by environmental contamination from the site. The qualitative
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risk assessment evaluates current as well as future potential exposures to
site related contamination. Sample results from the remedial investigation
were used to evaluate all environmental pathways with potential human exposure
routes.
The reasons that a qualitative, rather than a quantitative, risk assessment
was completed include:
* state standards for air and water quality are protective of human health
and the environment
* the remedy must comply with state standards
* EPA guidance documents state that exceedances of state standards,
whether or not the site represents an unacceptable risk, are a cause for
action at Superfund municipal landfill sites.
The groundwater, surface soil/sediment, and air pathways were evaluated as
possible exposure routes for contaminants. The groundwater data came from on-
site monitoring wells and off-site private water supply wells. No surface
water bodies are present on the site. The sediment samples were collected from
areas where runoff water, when present, would settle out and deposit sediment.
Soil gas samples and one ambient air sample were collected and used in the
evaluation of the air pathway.
A copy of the qualitative assessment is found in the administrative record.
Presented below is a brief summary of the assessment and it's conclusions.
Groundwater Pathway
The following compounds were identified as contaminants of concern:
benzene barium benzoic acid
chrysene iron diethylphthalate
tetrachloroethylene manganese 2,4-dimethyl phenol
vinyl chloride
1,1-dichloroethylene
The compounds listed in the first column represent probable carcinogens. The
qualitative health assessment concludes that persons who drink groundwater
every day, over a lifetime, with the highest concentration of these
contaminants detected in on-site monitoring wells are at an increased risk of
getting cancer. This does not represent a present use scenario since the wells
containing these concentrations are on Sauk County property and this water is
not being used for water supply purposes. This represents a possible, though
not probable, future use scenario. The future use scenario is not probable
since Chapter NR 812, Wis. Adm. Code pertaining to private water supplies
requires a minimum setback distance of 1200 feet from landfills.
The compounds listed in the second and third columns are not carcinogens, but
were evaluated for non-carcinogenic health effects. The qualitative risk
assessment concludes that there are no adverse health effects associated with
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exposure to these compounds at the highest concentrations detected in on-site
groundwater monitoring wells.
Two additional compounds were detected in monitoring of private wells around
the landfill. 1,1,1-trichloroethane and 1,1-dichloroethane were detected in
two private wells. The concentrations detected are far below the drinking
water standards for these compounds. The qualitative risk assessment concludes
that there are no adverse health effects expected from exposure to these
compounds in the private wells.
Surface Soil and Sediment Pathway
Because there are no surface water bodies at the site, the surface soil and
sediment data were evaluated together. The following compounds were identified
as contaminants of concern for surface soils:
arsenic beryllium polyaromatic hydrocarbons (PAHs)
lead manganese
Arsenic and beryllium are probable carcinogens. The concentrations of these
metals in surface soils are at concentrations that could cause an increased
risk of cancer if they were ingested at a rate of 100 mg/day for a lifetime.
This exposure is only appropriate for assessing exposures in urban areas or in
residential yards. Because the location of the surface soil contamination is
in a rural area that has restricted access, no increased cancer risk would be
expected from incidental exposures to the highest concentrations of arsenic
and beryllium.
PAHs were detected in samples of surface soils on-site. PAHs are created from
the incomplete combustion of fossil fuels. They are often associated with
vehicle emissions and/or oil and grease spills. Individual PAHs are rarely
identified in the absence of others. The health effects of the individual PAHs
may not be exactly alike. However, the coincident detection of a number of
these compounds makes it difficult to isolate health effects for individual
PAHs. For this reason the toxicity of these PAHs is evaluated as a group.
There are over one hundred different PAH compounds. Long term exposure to some
PAH compounds has been shown to cause cancer in humans exposed through
inhalation and dermal absorption. These PAHs were detected in soils at
concentrations that could cause an increased cancer risk if they were ingested
at a rate of 100 mg/day for a lifetime. This exposure scenario is only
appropriate for assessing surface soil exposures in urban areas or residential
yards. Because the location of the surface soil contamination is in a rural
area with restricted access, no increased cancer risk would be expected from
incidental exposures to the highest concentrations of PAHs at the site.
Arsenic, beryllium, lead and manganese were also evaluated for noncarcinogenic
health effects. Exposure to the highest concentrations of these compounds
detected in the surface soil samples is not expected to cause adverse health
effects.
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Air Pathway
Gas samples collected as part of the investigation were primarily soil gas and
not ambient air. Samples of soil gas are not indicative of ambient air quality.
It is expected that concentrations in ambient air would be considerably less
than those detected in soil gas. Because the data collected were for soil gas
and not for ambient air, the qualitative risk assessment does not include
estimates of potential exposure concentrations. The following compounds were
identified as contaminants of concern for the air pathway:
benzene
1,1-dichloroethylene
methylene chloride
tetrachloroethylene
vinyl chloride
f reon
acetone
methyl ethyl ketone
toluene
xylene
1,2-dichloroethylene
Those compounds listed in the first column are probable carcinogens and were
detected in soil gas at concentrations above that considered to pose a health
concern in ambient air. However, it is assumed that concentrations in the
ambient air would be considerably less than the concentrations detected in
soil gas.
Compounds listed in the second column were evaluated for non-carcinogenic
health effects. The highest concentration of these compounds detected in soil
gas were below levels that would be expected to cause adverse health effects.
In addition to carcinogenic and non-carcinogenic health effects, landfill gas
also represents another hazard. Methane generated by decomposing refuse, when
mixed with oxygen in the right concentration, is an explosion hazard. Soil gas
probes around the landfill detected methane at high enough concentrations to
represent an explosion and fire hazard.
To control the methane and other landfill gases listed above, the source
control remedy has an active gas collection and treatment system. The gas is
collected through a series of wells and piping. The gas is then routed to a
flare where it is destroyed by controlled combustion. The gas extraction
system was installed in late 1994.
VII. Description of the Remedial Alternatives
A. Groundwater Remedial Action Objectives
Remedial action objectives were developed for this site to provide short and
long term protection of human health and the environment, and to meet
applicable or relevant and appropriate requirements (ARARs). The site specific
groundwater remedial objectives for this landfill are to:
* Prevent migration of impacted groundwater in violation of NR 140, Wis.
Adm. Code
* Restore groundwater quality to standards in NR 140, Wis. Adm. Code
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B. Development of Alternatives
The remedial alternatives were assembled from applicable remedial technology
options. The alternatives surviving the initial screening were evaluated and
compared with respect to the nine criteria set forth in the National
Contingency Plan ("NCP")- In addition to the remedial action alternatives, the
NCP requires that a no-action alternative also be considered for the site. The
no action alternative serves primarily as a point of comparison for the other
alternatives.
C. Groundwater Alternatives
Alternative A - No Action
Alternative B - Pump and Treat Contaminated Groundwater
A complete description of the various alternatives is provided in the Focused
Feasibility Study for groundwater. A brief narrative description of each
alternative is provided below:
Alternative A: No Action
The No Action alternative is developed to act as a baseline to compare all
other alternatives against. This alternative consists of continued monitoring
of groundwater at both on-site monitoring wells and off-site private water
supply wells. All of the groundwater monitoring wells, and the private water
supply wells are considered points of compliance with respect to NR 140. The
groundwater quality data collected from the wells will be evaluated after the
monitoring plan has been in effect for 5 years. The evaluation will review
compliance with NR 140.
Alternative B: Pump and Treat Contaminated Groundwater
Under the pump and treat alternative, five (5) groundwater extraction wells
would be installed at various locations downgradient (west) of the landfill.
The wells would have a cumulative pumping rate of 50 gallons per minute. The
extracted water would be treated and then discharged to an intermittent
stream. All of the groundwater monitoring wells, and the private water supply
wells are considered points of compliance with respect to NR 140. The
groundwater quality data collected from the wells will be evaluated after the
monitoring plan has been in effect for 5 years. The evaluation will review
compliance with NR 140.
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
A. Introduction
U.S. EPA has established in the NCP nine criteria that consider health
impacts, technical and cost considerations to determine the most appropriate
remedial alternative. The criteria are designed to select a remedy that will
be protective of human health and the environment, attain ARARs, utilize
permanent solutions and treatment technologies to the maximum extent
practicable, and be cost effective. The relative performance of each of the
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remedial alternatives listed above has been evaluated using the nine criteria
set forth in the NCP at 40 CFR 300.430(e)(9)(iii) as the basis of comparison.
These nine criteria are summarized as follows:
THRESHOLD CRITERIA - The selected remedy must meet the threshold criteria.
1. Overall Protection of Human Health and the Environment
A remedy must provide adequate protection and describe how risks are
eliminated, reduced or controlled through treatment, engineering
controls or institutional controls.
2. Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs)
A remedy must meet all applicable or relevant and appropriate
requirements of federal/state laws. If not, a waiver may apply.
PRIMARY BALANCING CRITERIA are used to compare the effectiveness of the
remedies.
3. Long-term Effectiveness and Permanence
Once clean up goals have been met, this refers to expected residual risk
and the ability of a remedy to maintain reliable protection of human
health and the environment over time.
4. Reduction of Toxicity, Mobility or Volume Through Treatment
The purpose of this criteria is to anticipate the performance of the
treatment technologies that may be employed.
5. Short-term Effectiveness
This refers to the potential adverse impacts on human health and the
environment during the construction and implementation period.
6. Implementability
This criteria requires consideration of the technical and administrative
feasibility of a remedy, including whether needed services and materials
are available.
7. Cost
Capital, operation and maintenance, and 30 year present worth costs are
addressed.
MODIFYING CRITERIA deal with support agency and community response to the
alternatives.
8. State Acceptance
After review of the Focused Feasibility Study and the Proposed Plan,
support agency's concurrence or objections are taken into consideration.
9. Community Acceptance
This criteria summarizes the public's response to the alternative
remedies after the public comment period. The comments from the public
are addressed in the Responsiveness Summary attached to this ROD.
B. Evaluation of the Remedial Alternatives for Groundwater
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1. Threshold Criteria
The threshold criteria are CERCLA statutory requirements that must be
satisfied by any alternative in order for it to be eligible for selection as a
CERCLA-quality remedy. These two criteria are discussed below:
a. Overall Protection of Human Health and the Environment
Alternative A - Groundwater concentrations of VOCs have shown a decreasing
trend over the past several years. If the trend continues, all VOCs should
achieve compliance with standards in NR 140, Wis. Adm. Code and Ch. 160
Stats., within the next couple of years. Drinking water standards for VOCs are
only exceeded at wells within 150 feet of the landfill. This water is not
currently used for drinking water purposes, nor is it likely to be used for
drinking water purposes in the future.
Monitoring of the on-site wells and select off-site private water supply wells
will ensure protection of human health and the environment. This alternative
complies with this threshold criterion.
Alternative B - This alternative would capture contaminated water located near
the landfill, keeping it from spreading any further downgradient. The captured
water would be treated to remove contaminants, and then discharged. This
alternative complies with this threshold criterion.
b. Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs)
Alternative A - Chapter 160, Stats., and NR 140, Wis. Adm. Code contains
groundwater quality standards, and sets forth actions that may be required to
be taken when groundwater standards are exceeded. One such action, a source
control action, has already been implemented at this landfill. Groundwater
quality is showing an improving trend. Required actions within NR 140 also
include implementation of groundwater monitoring. This alternative complies
with applicable or relevant and appropriate requirements because it appears
that the source control action that has already been implemented will bring
the site into compliance with NR 140 groundwater quality standards within a
reasonable period of time.
Alternative B - A remedial action to renovate or restore groundwater quality
is a potentially required action listed in NR 140 when a groundwater quality
standard is exceeded. Pumping and treating the groundwater is considered an
action to renovate or restore groundwater quality.
The federal Safe Drinking Water Act (40 CFR, Part 142) is the federal ARAR
which lists federal drinking water standards. Groundwater quality standards
listed in ch. 160, Stats., and NR 140, Wis. Adm. Code are at least as
stringent as those standards listed in the Safe Drinking Water Act. This
alternative complies with applicable or relevant and appropriate requirements.
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2. Primary Balancing Criteria
Alternatives which satisfy the two threshold criteria are then evaluated
according to the five primary balancing criteria.
a. Long-term Effectiveness and Permanence
Alternative A - This alternative offers long term protection of human health
and the environment because groundwater monitoring will continue indefinitely.
A decision on changing the monitoring would be made once groundwater data
clearly indicate compliance with NR 140 standards.
Alternative B - This alternative offers long term effectiveness since
capturing and treating the contamination will remove contaminants from the
groundwater.
b. Reduction in Toxicity, Mobility or Volume Through Treatment
Alternative A - The selected remedy doesn't include active treatment of the
groundwater contamination. However, groundwater monitoring data indicate that
VOC concentrations are decreasing. The cause of this decrease is attenuation,
dispersion, degradation and dilution. These processes, acting together with
the source control action already taken at the site, will likely cause
groundwater VOC concentrations to decrease within a reasonable period of time
to a point at which VOC concentrations will comply with standards found in NR
140.
Alternative B - Pumping and treating the groundwater would actively reduce the
mobility and volume of contamination through treatment. Compliance with NR 140
standards may be achieved more quickly than under Alternative A.
c. Short-term Effectiveness
Alternative A - There would be no short term adverse effects by implementing
this alternative, namely because it is already in place. A groundwater
monitoring plan was approved as part of the source control remedy.
Alternative B - This alternative would have only minor short term adverse
impacts. Installation of a pump and treat system would require construction of
a well and treatment facility. Any mechanical construction has physical risks
associated with it. However, these risks can be minimized by using standard
engineering and construction practices, and by using a contractor familiar
with this construction.
d. Implementability
Alternative A - This alternative has already been implemented. A groundwater
monitoring plan was approved as part of the source control remedy and has been
implemented since the fall of 1994.
Alternative B - This alternative is easily implemented. Groundwater extraction
and treatment systems have been used for many years. There are
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many consulting firms and contractors available with the skill to properly
design and build this remedy.
e. Costs
Alternative A
Capital Costs - $0.00
Annual Costs - $25,000
Net Present Worth - $344,000
Alternative B
Capital Costs - $261,000
Annual Costs - $87,000
Net Present Worth - $1,458,000
3. Modifying Criteria
a. State Acceptance
The WDNR is the lead agency on this case and authors this ROD.
b. Community Acceptance
No comments were received from the public during the public comment period.
c. Summary
Both of the alternatives meet the threshold, balancing and modifying criteria.
The difference between the two is one of complexity and cost. Groundwater VOC
concentrations have been decreasing for the past several years. The original
landfill cap appears to have substantially reduced the amount of contamination
leaving the landfill. The cap was improved as part of the source control
remedy. This should further decrease the contamination leaving the landfill.
Given that groundwater quality is improving at an acceptable rate, there isn't
any need for a groundwater pump and treat remedial system. With the decreasing
trend in VOC concentrations groundwater standards should be achieved sometime
in the next couple of years. The pump and treat remedy may only decrease this
by a year or less. The marginal benefits of time gained by implementing a pump
and treat system aren't warranted when compared to the cost of implementing
such a system.
CONCLUSIONS OF LAW
Alternative A will protect human health and the environment by monitoring
changes in groundwater quality with time, will comply with all legally
applicable, or relevant and appropriate requirements for this final
groundwater remedy, and will be cost effective.
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A. Protection of Human Health and the Environment
The selected remedy provides protection of human health and the environment by
monitoring changes in groundwater quality over time.
B. Attainment of ARARs
The selected remedy complies with NR 140, Wis. Adm. Code by monitoring changes
in water quality after a source control remedy has been implemented.
Monitoring groundwater is one of the potentially required actions listed in
Table 5 of NR 140, Wis. Adm. Code. Contaminant concentrations in groundwater
have been decreasing at an acceptable rate for the past several years. Natural
attenuation, degradation and dilution are likely causing this improvement in
water quality. Should this trend continue, all contaminants should be below
their respective preventive actions limits within the next 2-3 years.
C. Cost Effectiveness
The selected remedy provides for overall cost effectiveness. Groundwater
quality is improving as a result of the effectiveness of the landfill cap in
reducing infiltration into the waste, and the natural processes of
degradation, attenuation and dilution in retarding contaminant movement within
the groundwater. Since groundwater quality is improving at a reasonable rate,
an active and more expensive groundwater remedy of pump and treat isn't
necessary. Monitoring of the groundwater quality is the most cost effective
remedy.
D. Utilization of Permanent Solutions and Alternative Treatment Technologies
Groundwater monitoring is neither a permanent solution nor an alternative
treatment technology. The source control remedy included capping the landfill
and it is a permanent solution.
E. Preference for Treatment as a Principal Element
Due to the improving groundwater quality, active groundwater treatment
measures aren't necessary.
THE SELECTED REMEDY
Based on an evaluation of the alternatives, the Wisconsin Department of
Natural Resources believes that Alternative A, the selected remedy, will be
protective of human health and the environment, comply with ARARs, be cost
effective, and will use permanent solutions to the maximum extent practicable.
The selected groundwater remedy for the site includes the following:
* continued monitoring of the groundwater at 12 on-site groundwater
monitoring wells and 6 off-site private wells
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This monitoring was required as part of the source control record of decision
and has already been implemented. A groundwater monitoring plan approved by
WDNR was started in the fall of 1994. The approved plan requires the
monitoring of VOCs and water levels, and also requires that an analysis of the
data take place every five years to determine whether the groundwater is in
compliance with NR 140, Wis. Adm. code. This report will be submitted to WDNR
for review. The water quality data from each of the wells in the monitoring
program will be used to determine compliance with NR 140.
The WDNR has determined that the selected remedy, Alternative A, will achieve
the groundwater remedial action objectives for this site.
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RESPONSIVENESS SUMMARY
The Department of Natural Resources originally issued the proposed plan for
groundwater between March 3, 1995 and April 10, 1995. At that time a fact
sheet announcing the proposed plan was sent to all persons living near the
site, politicians, news media and all other who have shown an interest in this
site. The Department didn't receive any comments from the public during this
time frame.
At the time of announcing the proposed plan, the Department failed to place an
add in the newspaper indicating the availability of a proposed plan. This
newspaper add is a CERCLA requirement. To comply with CERCLA, the Department
placed an add in the Baraboo News Republic announcing the proposed plan for
groundwater. The add was placed on June 29, 1995 and the public comment period
ran between June 29 and August 1, 1995. The Department didn't receive any
public comments.
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UNITED STATES ENVIRONMENTAL PROTECTTON
REGION 5
77 WEST JACKSON BOULEVARD
CHICAGO, H. 6Q6Q4-35SQ
flEPi.V td THE »rVtNT:-D!H OF
Mr., George E. Meyer
Secretary
Wisconsin Department of Natural Resources
101 South Webster Street
Madison, Wisconsin 53707
RE: Sauk County Landfill Superfund Site
Dear Mr. Meyer:
The United States Environmental Protection Agency (U.S. EPA) hereby
concurs with the no action remedy in the groundwater Record of
Decision.(ROD) completed by the Wisconsin Department of Natural
Resources (WDNR) for the Sauk County Landfill Superfund Site. This
concurrence is in accordance with 40 CFR Section 300.515 (e) (2) (i) and
(ii). The no action remedy does include continued monitoring of the
groundwater at on-site groundwater monitoring wells and off-site
private yells.
U.S. EPA understands that this ROD identifies the final remedy and/or
decision for the site. The 1994 source control ROD included
regrading of the landfill cap and installation of a gas collection
system to control the source of groundwater contamination. Since
groundwater data collected by Sauk County since the 1980's,
demonstrates a significant decrease in volatile organic compounds
(VOCs) overtime, U.S. EPA concurs with WDNR's determination that an
active groundwater treatment is not necessary at the site. U.S. EPA
understands that the long term monitoring of the groundwater will be
evaluated after five years to determine the remedy's compliance with
the laws and the terms set forth in the 1994 source control ROD.
U.S. EPA congratulates the State of Wisconsin for completing the
successful remediation of Sauk County Landfill by using a common
sense approach and an expedited timeframe.
Valdaa V.
Regional AdminstraLar
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