PB98-963142

                              EPA 541-R98-154

                              March 1999
EPA Superfund
      Explanation of Significant Difference
      for the Record of Decision:
      Refuse Hideaway Landfill
      Middleton,WI
      9/30/1998

-------
                                                                       SEP  30
                 EXPLANATION OF SIGNIFICANT DIFFERENCES
                       REFUSE HIDEAWAY LANDFILL SITE
                             MIDDLETON, WISCONSIN
                                 SEPTEMBER, 1998

INTRODUCTION

This Explanation of Significant Differences (ESD) is for the Refuse Hideaway Landfill
Superfund site in Middleton, Wisconsin.  This ESD is being issued pursuant to Section 117 of
the Comprehensive Environmental Response. Compensation and Liability Act, as amended, and
Section 40 CFR 300.435(c)(2)(i) of the National Contingency Plan by the United States
Environmental Protection Agency (U.S. EPA) in cooperation with the Wisconsin Department of
Natural Resources (WDNR). U.S. EPA is the lead agency for this site and WDNR is the support
agency.

This ESD describes and provides explanation of significant differences in the following
components of the remedy selected in the June 28. 1995 Record of Decision (ROD): "Alternative
F, Groundwater Extraction and Treatment with Reinjection to Enhance Natural Breakdown of
Contaminants." This ESD will be included in the Administrative Record for the site.  The
Administrative Record is available at the  information repositories identified at the end of this
document.

SITE BACKGROUND

Site Description

Refuse Hideaway Landfill was listed on the National Priorities List (NPL) by the U.S. EPA in
October 1992.  Refuse Hideaway Landfill (RHL) is located in the SW1/4, NW1/4, Section 8.
T7N. R8E. Town of Middleton,  Dane County. Wisconsin (See Figure 2-1, Site location map).
The 1.2 million cubic  yard landfill containing municipal, commercial and industrial waste is
located in the rural portion of the Town of Middleton. 2 miles west of the City of Middleton and
4 miles east of the Village of Cross Plains.  According to the 1990 census, there  are 3.628
persons living in the Town of Middleton.

RHL is located in the  easternmost section of the upper Black Earth Creek drainage basin. Land
use in the area surrounding the landfill is diverse. The landfill property itself, outside the fill
boundary, is currently being rented by the landfill owner to a sand and  gravel company as a
storage area  for truck and construction equipment. The north and west side of the landfill
property are  bounded  by a Christmas tree farm, while the remaining area surrounding RHL  is
predominantly agricultural with field corn and other dairy  support crops being the most common
output. A small wetland area is located southeast of the landfill.  Several residences are located
near the landfill. Most homes are located adjacent to County Highway 14 or in the Deer Run
Heights Subdivision to the southwest of the landfill.

Private water supply wells provide water for the residences and agricultural uses in the RHL

-------
area.  Approximately 53 homes are within 1 mile of the Site. Three private wells down gradient
of the landfill have had Volatile Organic Compounds (VOCs) detected in them. One of these
residences is currently vacant while two others have treatment systems in place to treat the
documented groundwater contamination.

Immediately surrounding the landfill, there appears to he a localized radial component of
groundwater How from the landfill. To the north of the landfill, groundwater at the water table
flows to the north, essentially against the  regional flow direction. The apparent radial flow
pattern emanating from the landfill to the north appears to he limited to the upper 50 feet of the
saturated strata. Groundwater flow at depth migrates to the southwest, consistent with the
documented regional flow pattern to the southwest.

Groundwater flow in the unconsolidated deposits to the south and east of the landfill is to the
south, while further off the Site to the south, the flow direction changes and merges with the
regional flow direction which trends  in a southwesterly direction. This southwesterly direction
of flow is also observed within the topographic ridges to the west and southwest of the landfill.

No endangered species are known  to be located in the vicinity of RHL.  There are no historic
landmarks that would be potentially affected by RHL.

Site History and Enforcement Activities

John Debeck. the owner and operator of the Refuse Hideaway Landfill, received a landfill license
from the  Wisconsin Department of Natural Resources (WDNR) in 1974 to operate a 23 acre
landfill. The main engineering requirement was that he maintain at least 10 feet of soil between
the waste and bedrock and that he daily cover the waste. Numerous violations of the daily cover
requirements are noted in the WDNR file of the site. The site was filled from south to north, but
was not operated in "phases"'. Therefore, the entire waste volume (approximately 1.2 million
cubic yards) was exposed to leaching by rain and snow melt throughout the operating history.
The landfill owner reported receiving a variety of commercial and industrial wastes including:
full barrels of glue and paint, barrels of ink and ink washes, spray paint booth by-products and
paint stripper sludge, and spill residue containing VOCs. In addition, large volumes of other
types of waste were received from local industries, businesses, and cities and towns in Dane
County were also disposed at the landfill.

John Debeck closed the landfill under court order in May.  1988. At that time, he covered the
landfill in accordance with NR 504.07, WI Adm. Code, and placed a 6 inch grading layer of
coarse soil over the waste, followed by 2  feet of clay soils.  Two and a half feet of general soils
were placed over the clay and 6 inches of topsoil. seeded and mulched, finished the cap.  The
final cover was completed in October, 1988.  In January. 1989. John DeBeck declared
bankruptcy and was unable to undertake additional remediation of the landfill or investigation of
the degree and extent of groundwater contamination.

-------
Therefore, in early 1989. the State of Wisconsin undertook the continued remediation and
investigation of the site, as well as all operation and maintenance activities. Costs for this work
were paid by the State of Wisconsin's Environmental Fund which are monies from a variety of
sources, including fees paid by the owners and operators of solid waste landfills, hazardous
substance generator fees, licensing fees for pesticide use and general tax revenues.

In Fall. 1989. the State began a number of actions designed to remediate the immediate problems
of: .

       1.  Methane gas and leachate migration from the landfill.
       2.  Private water supply contamination at three wells.
       3.  Groundwater contamination and possible contamination of additional private wells.

The following actions were taken:

1.      Installation of a gas and leachate extraction system in the landfill.

2.      Long-term operation and maintenance of the gas/leachate extraction system.

3.      Repair of the landfill cap.

4.      Methane gas monitoring at private homes.

5.      Point-of-entry (POE) water treatment systems installed in two private water supply uells.

6.      Testing of private water supplies within one mile of the landfill.

7.      Groundwater monitoring study.  In Summer. 1990. the State undertook an intensive
       groundwater investigation to determine the degree and extent of VOC contamination.
       Hydro-Search. Inc. of Brookfield, WI performed the  investigation. Twenty-seven
       groundwater  monitoring wells were installed. There were  30 existing monitoring wells
       at the Site, for a total of 57 monitoring wells in the study. (See Figure 3-4. total VOCs in
       groundwater, 1991) The  study evaluated the geology, the vertical and horizontal
       groundwater flow,  the average groundwater velocity in each geologic unit, the extent of
       aquifer contamination the direction of plume movement, preliminarily evaluated four
       remedial actions, and made recommendations on future work at the Site.  The study
       showed that the groundwater plume had the potential to contaminate groundwater 1 mile
       southwest of the landfill. In January, 1991. the State began monitoring private wells in
       the southern portion of Deer Run Heights.

8.     Numerical model simulation and assessment of contaminant plume migration.

9.     Testing for metals, semi-volatiles compounds, pesticides and PCBs.

-------
10.     Long term groundwater monitoring.

In 1991. the WDNR offered to enter into a contract with a group of PRPs to undertake a remedial
investigation and feasibility study (RI/FS) at RHL. After being unable to secure an agreement.
and after reviewing data from the site, the WDNR recommended to EPA that the site be included
on the National Priorities List (NPL). The site was listed on the NPL in October 1992. A
Cooperative Agreement was signed between U.S. EPA and WDNR in April 1993 allowing the
WDNR to act as lead agency in performing an PITS pursuant to s. 144.442. Wisconsin Statutes
(now renumbered as s. 292.31 Wisconsin Statutes) and CERCLA.  The RI/FS for this site was
financed by the federal Superfund program.  The WDNR secured a consultant. Hydro-Search.
Inc.. and the RI/FS officially began in October 1993.

The RI for RHL was completed in September 1994 and the FS was completed in February 1995.
The WDNR issued a Record of Decision (ROD) in June. 1995. The ROD selected Alternatives
B (Limited Action for Source Control). Alternative F (Groundwater Extraction and Treatment
with Reinjection to enhance In-Situ Bioremediation) and Alternative G (Supply Individual Water
Treatment Units) as the Final Remedy for the site.

DESCRIPTION OF SIGNIFICANT DIFFERENCES AND BASIS FOR THE
DIFFERENCE

This ESD documents a significant difference in the selected remedy. The June 28. 1995 ROD
required groundwater extraction and treatment of the most highly contaminated groundwater
(greater than 200 ppb total volatile organic compounds (VOCs)). treatment of groundwater to
discharge standards and injection of the treated water into the aquifer upgradient of the landfill to
stimulate in-situ biodegradation of the degradable components of the contamination. Sampling
conducted in early 1998 as  part of Remedial Design demonstrated that groundwater
contamination has decreased below the  1995 ROD action level of 200 ppb total VOCs (See
Figure 3-5, total VOCs in groundwater, 1998). Therefore, this ESD documents that U.S.  EPA. in
consultation with the WDNR. has determined, based on the 1998 groundwater data, that it is not
necessary to implement the groundwater extraction and treatment component of the selected
remedy. At the time that the  1995 ROD was issued groundwater levels underneath the landfill
exceeded 700 ppb total VOCs (see Figure 3-5 of the February 3. 1995 Feasibility Study (FS)
Report).  In 1998. groundwater contaminant levels under the landfill are less than 200 ppb total
VOCs (See Figure 3-5 in this ESD). This significant decrease of total VOCs in groundwater
over a short period of time  indicates that groundwater should meet the remedial action objective
of NR 140 PALs within a reasonable period of time if source control measures continue to be
operated and maintained. The groundwater remedial action objective, as stated on page 29 of the
 1995  ROD. to "attain the Wisconsin NR 140 Preventative Action Levels (PALs) for all
groundwater impacted by the RHL at and beyond the landfill boundary." is not being modified
by this ESD.  Monitoring of groundwater and continued operation and maintenance of the
landfill cap and gas/leachate extraction systems in conjunction with five year reviews will
continue until the groundwater remedial action objectives are attained.

-------
The other key provisions of the June 28. 1995 ROD that will remain the same are:

•      Alternative B, Source Control Limited Action. Add deed restrictions/zoning and
       perimeter signs to the site. Maintain the existing soil cap and operate and maintain the
       existing gas/leachate collection system.  Continue to monitor 21 groundwater monitoring
       wells and 12 private homes for VOCs.

•      Alternative G, Supply Individual Water Treatment Units. This is a contingent option if
       the area of groundwater contamination moves and additional homes become
       contaminated. Point-of-entry (POE) treatment units would be installed at homes that
       become contaminated or are imminently threatened with contamination.  Currently. POE
       systems are successfully treating water at two homes downgradient of the landfill.

The Remedial Design (RD) phase began on April 8. 1997 when U.S. EPA entered into an
Administrative Order on Consent (AOC) for RD with forty-two (42) Potentially Responsible
Parties (PRPs). The AOC requires the PRPs to conduct Pre-Design Studies and then Remedial
Design. The Pre-Design Studies were completed in July 1998 and consisted of:  (1) sampling of
51 groundwater monitoring wells for VOCs; (2) sampling leachate extraction wells, 13 gas
extraction wells, and 11 gas probes on the landfill; (3) sampling of 12 groundwater monitoring
wells for natural attenuation parameters; and (4) an evaluation of the integrity of the new Schultz
well.

The groundwater samples collected in February and March  1998 were analyzed  in accordance
with the EPA-approved Quality Assurance Project Plan (QAPP) procedures established for
analytical work at this site. .The results of groundwater sampling showed that none of the wells
contained total VOCs at concentrations above 200 ppb (See Figure 3-5, total VOCs in
groundwater, 1998). The highest total VOC concentration was found in well P-21D at 178 ppb.
Therefore, the concentrations of total VOCs in groundwater are below the action level of 200 ppb
total VOCs set in the June 28, 1995 ROD that would have triggered groundwater extraction and
treatment. In other words,  because the  1995 ROD called for installation of groundwater recovery
wells in order to remediate groundwater contaminated above 200 ppb total VOCs, and because
groundwater is no longer contaminated above this level, no groundwater extraction and treatment
is currently required by the 1995 ROD.

The decrease of total VOC concentrations in groundwater is likely the result of several processes:
source control  measures consisting of leachate extraction and gas extraction from the landfill are
removing significant mass  of VOC contamination from the landfill and thus reducing the mass of
VOCs entering groundwater; and to a lesser degree natural degradation, dilution and dispersion
of VOC contamination  in groundwater.  Analysis of natural attenuation parameters indicate that
conditions appropriate for degradation of PCE and TCE are present within and probably beneath
the landfill. Conditions appropriate for degradation of DCE and vinyl chloride are present in the
groundwater around and downgradient of the landfill. These contaminants (PCE, TCE, DCE and
vinyl chloride) constitute the majority of the VOC contamination in groundwater.

-------
U.S. EPA in consultation with WDNR has determined, based on the 1998 groundwater data, that
it is not necessary to implement the groundwater extraction and treatment component of the
selected remedy. The groundwater plume appears to be stable and thus does not pose any
additional threat to human health or the environment. Five year reviews of the site will be
conducted until the groundwater remedial action objectives are achieved.

COST

The 1995 ROD estimated that the cost of groundwater extraction and treatment with reinjection
would be $2.737.000.  Because groundwater sampling in 1998 indicates there is no groundwater
exceeding the 1995  ROD action level of 200 ppb total VOCs these costs will not need to be
incurred at this time.

SUPPORT AGENCY COMMENTS

The WDNR has indicated their concurrence with this ESD.

AFFIRMATION OF STATUTORY DETERMINATIONS

The modified remedy continues to satisfy statutory requirements. Considering the new
information that has been developed and the change that has been made to the selected remedy.
U.S. EPA and WDNR believe that the remedy remains protective of human health and the
environment, complies with Federal and State requirements that are applicable or relevant and
nppropriate to this remedial action, and is cost effective.  In addition this revised remedy utilizes
permanent solutions and alternative treatment (or resources recovery) technologies to the
maximum extent practicable for this site.

PUBLIC PARTICIPATION ACTIVITIES

U.S. EPA and WDNR held a meeting on February 23, 1995 to announce the completion of
Remedial Investigation and Feasibility Study activities and explain the ROD components for
final remedial action at the site. Copies of the June 28. 1995 ROD and other site related
documents including this ESD are available at the information repositories mentioned below:

Middleton Public Library
7425 Hubbard Avenue
Middleton, Wisconsin

U.S. EPA
Records Center, 7th floor Metcalf Building
77 W. Jackson Blvd.
Chicago. IL 60604

-------
                                        •^•SITE LOCATION

BASE MAP DEVELOPED FROM THE
MIODLETON. WISCONSIN 7.5  MINUTE
U.S.G.S. TOPOGRAPHIC QUADRANGLE MAP,
DATED 1983.
        QUADRANGLE LOCATION
SCALE IN FEET
         RJR
                       Drnm By
                                         8TTE LOCATION
         Doug J. Bach
7/20/98
                                         PREDESIGN AND ADDITIONAL STUDIES
                                         REFUSE HIDEAWAY LANDFILL
                                         MIDDLETON. WISCONSIN

-------
I
i;

I
                    f
                                                                                                                                                                   UEQBffi
                    REFUSE HIDEAWAY LANDFILL
                    PROPERTY BOUNDARY
                                                                                                                                                                   ._— .  FILL LIMITS
                                                                                                                                                                            MONITORING WELL LOCAHOM.
                                                                                                                                                                            NUMBER. AND TOTAL VOC
                                                                                                                                                                            CONCENTRATION RESULTS
                                                                                                                                                                            (ufl/0
                                                                                                                                                                            yoNiroRiNc WELL LOCATION
                                                                                                                                                                            AND NUMBER (NOT SAMPLED

                                                                                                                                                                            PRIVATE WELL LOCATION
                                                                                                                                                                            AND NUMBER (NOT SAMPLED
                                                                                                                                                                            »NEW SCHULTZ WELL
                                                                                                                                                                            LOCATION
               3-y
                                                                                                                                                                            STAFF GAGE LOCAHON
                                                                                                                                                                            AND NUMBER
                                                                                                                                                                            RAILROAD
                                                                                                                                                                            WETLANDS
                                                                                                                                                                            CREEK OR INTERMITTENT
                                                                                                                                                                            STREAM
                                                                                                                                                              	   	10— ISO-CONCENTRATION
                                                                                                                                                                            CONTOUR (CONTOUR
                                                                                                                                                                            INTERVAL-  VARIES. DASHED
                                                                                                                                                                            WHERE INFERRED)

                                                                                                                                                                            >SOO uflA

                                                                                                                                                                            200  - SOO ug/L

                                                                                                                                                                            100-200 ug/L

                                                                                                                                                                            50 - 100 ug/L

                                                                                                                                                                            10 - SO uj/L
                                                                                                                                        north
                                                                                                                                           1000
                                                                                                                                SCALE IN FEET
9000
(KOB

1.  BASE MAP OCVELOPED FROM MARCH
   1B01 EXISTING CONOmONS PLAN
   F0« REFUSE HIDCAWAY LANDHLU
   PREPARED BY HYDRO-SEARCH.
   INC.. DATED JUNE 20. 199*.

2.  DATA USED FOR ISO-CONCEVTRAT10M
   MAP FROM JANUARY 1881
   SAMPLING EPISODE.  IF NO
   JANUARY  EPISODE OCCURRED.
   THE  EARLIEST SAMPLING  TIME IN
   1991  WAS USED.

3.  WHERE WELL  NESTS OCCUR. THE
   WELL WITH THE HIGHEST TOTAL
   VOC  CONCENTRATION WAS USED
   FOR  PLOTTING.
                                             FlUUT»a-4

-------
i S
A:>     .'   J
                                                                                                                                                             UEOCHD
                5 '••
                                                                                                       °>          VK»
                                                                                               	   _%'	.7/(.- _ji
                                                                                                      *r^~Tfr\~"'
                                                                                                                                                                      REFUSE  HIDEAWAY LANDFILL
                                                                                                                                                                      PROPERTY BOUNDARY
                                                                                                                                                              -- — -.  flu. UUITS
                                                                                                                                                                      MONITORING WtU LOCATION.
                                                                                                                                                                      NUMBER. AND TOTAL VOC
                                                                                                                                                                      CONCENTRATION  RESULTS
                                                                                                                                                                      SMONITORINC WELL LOCATION
                                                                                                                                                                      AND NUMBER (NOT SAMPLED

                                                                                                                                                              :'W-V-  PRIVATE WELL LOCATION
                                                                                                                                                                  *  AND NUMBER (NOT SAMPLED

                                                                                                                                                                  £.  NEW SCHULTZ WEU
                                                                                                                                                                  !*  LOCATION  AND TOTAL VOC
                                                                                                                                                                      CONCENTRATION  RESULT
                                                                                                                                                                 S'V  STAFF CAGE LOCATION
                                                                                                                                                                   7" AND NUMBER
                                                                                                                                                       RAILROAD

                                                                                                                                                       WETLANDS

                                                                                                                                                    _ CREEK OR INTERMITTENT
                                                                                                                                                       STREAM

                                                                                                                                              	10— ISO-CONCENTRATION
                                                                                                                                                       CONTOUR (CONTOUR
                                                                                                                                                       INTERVAL  VARIES  DASHED
                                                                                                                                                       WHERE INFERRED)

                                                                                                                                                 H   >IOO u»A - <200 ufl/L

                                                                                                                                                J||   SO -  100 ug/L

                                                                                                                                                 •   10-90 u«/L
                                                                                                                    north
                                                                                                             0          1000        2000
                                                                                                                           SCALE IN FEET
                                                                                                                                                            MQTM

                                                                                                                                                               BASE IMP DEVELOPED FROM MARCH
                                                                                                                                                               1MI EXISTING CONDITIONS  PLAN
                                                                                                                                                               FOR REFUSE HIDEAWAY LANDFILL.
                                                                                                                                                               PREPARED BY HYDRO-SEARCH.
                                                                                                                                                               INC.. DATED JUNE 20. 1994.

                                                                                                                                                            2.  DATA USED FOR ISO-CONCENTRATION
                                                                                                                                                               MAP FROM FEBRUARY AND MARCH
                                                                                                                                                               1998.   DATA WAS BLANK CORRECTED
                                                                                                                                                               BUT.  THE VALIDATION PROCESS WAS
                                                                                                                                                               NOT COMPLETED AT  THE TIME OF
                                                                                                                                                               ISO-CONCENTRATION MAP
                                                                                                                                                               COMPLETION.

                                                                                                                                                            3.  WHERE  WELL NESTS  OCCUR.  THE
                                                                                                                                                               WELL WITH THE HIGHEST TOTAL
                                                                                                                                                               VOC CONCENTRATION WAS USED
                                                                                                                                                               FOR PLOTTING.

-------