Congressional District # 02
CITY DISPOSAL CORP. LANDFILLEPA ID# WID980610646
Last Updated: November, 2011
Site DescriptionThe City Disposal Corporation Landfill (CDCL) site is located on approximately 38 acres of land in Dane County, Wisconsin. The landfill was opened in the mid-1960s and closed in 1977. During the years of the site's operation, the surrounding area was rural. With the growth of the Madison area, this is changing. Household wastes, industrial wastes, general construction wastes, and debris were disposed of at the site. Industrial wastes included, but were not limited to, discarded solvents from plastics manufacture, paint wastes, oily residues, etc. Total volume of wastes disposed of is approximately 700,000 cubic yards. Of the 12 cells which existed at the site for waste disposal, Cells 6 and 12 received largely industrial wastes. The site was placed on the National Priorities List (NPL) in 1984. In 1987 and 1988, various potentially responsible parties (PRPs) entered into an agreement with the United States Environmental Protection Agency (U.S. EPA) to conduct a remedial investigation and feasibility study (RI/FS). This effort was completed in 1992. The main groundwater contaminants associated with the site include: tetrahydrofuran (THF), 2- butanone, acetone, carbon tetrachloride, trichloroethene, and toluene.
Utilizing a Consent Decree, Waste Management of Wisconsin has taken technical lead in performing necessary remedial design, remedial construction, and day-to-day operation and maintenance of treatment facilities. U.S. EPA and Wisconsin DNR perform oversight of such activity, and review effluent quality reports and other maintenance records as generated by Waste Management of Wisconsin.
Threats and ContaminantsOnsite groundwater and soil are contaminated with volatile organic compounds (VOCs). Potential health threats to people include: drinking contaminated groundwater, accidentally ingesting contaminated soil, inhaling contaminated dust and air particles, and coming into direct contact with contaminated groundwater and soils. Grass Lake, a habitat for sandhill cranes and other wildlife, is located about 700 feet northeast of the site and could be subject to pollution from site runoff.
Cleanup ProgressIn September 1992, U.S. EPA signed a record of decision (ROD), calling for placement of a nonhazardous waste cover over the majority of the site, placement of a hazardous waste cover over Cells 6 and 12, landfill gas venting and treatment, and groundwater extraction and treatment along with appropriate monitoring. In March 1993, U.S. EPA issued a unilateral administrative order (UAO) which required that a remedial design and remedial action (RD/RA) be conducted. (Note - As of the summer of 2005, the UAO has been replaced by a Consent Decree which will now serve as the primary enforcement document covering site work).
The remedial work at the City Disposal Corporation Landfill site has proceeded in two distinct phases. It was reasoned that a reduction in infiltration of precipitation through the waste mass would help in simplifying groundwater control efforts. Hence, following remedial design approval by the agencies, installation of the landfill gas collection system and clay cap was performed from June through October 1995. Work on the collection system involved the excavation of trenches followed by the installation of piping. The cap included a two-foot thick clay cap over the entire landfill, a 40 mil high-density polyethylene geomembrane cap, a geonet/geotextile composite drainage layer over Cells 6 and 12, and an 18-inch cover soil and six-inch topsoil layer over the entire landfill. Attention shifted to groundwater control elements of the remedy. Since treatability tests, using site water samples, indicated nearly equal weight to treating groundwater by biological or physical-chemical means, U.S. EPA and the Wisconsin Department of Natural Resources (WDNR) worked with the potentially responsible party in devising a strategy that would promote the remedial action and help provide information to determine the most efficient and cost-effective means of permanent treatment.
In June 1997, U.S. EPA signed with WDNR's concurrence, an explanation of significant differences (ESD) which allows groundwater extraction and interim treatment at the nearby Madison Publicly Owned Treatment Works (POTW). Under most circumstances, water could not be hauled more than five days per week, and usually only daily, and about 8,000 to 10,000 gallons of contaminated groundwater could be transported daily. WDNR carefully reviewed the ability of the POTW to accept such groundwater for an interim period of about six months and concluded that the POTW could successfully treat the groundwater.
From September to December 1997, the potentially responsible party installed extraction pumps, electrical hookup, piping, tanks, etc. Monitoring results were compiled and temporary offsite hauling of collected groundwater began in early 1998. Basically, the degree of change in contaminant levels had provided the potentially responsible party with information necessary to make a commitment to a permanent treatment system at the City Disposal Corporation Landfill. Using information derived from the interim remedial groundwater action, design for the permanent onsite treatment system was completed in 1999, and construction of the system had begun. Construction continued in spring 2000 when the fixed-film bioreactor system came on line. Discharge is first routed to a wetland area, and subsequently to a swale to Badfish Creek. Effluent limits were assigned by WDNR. Monitoring will check on effluent quality and aquifer response.
The U.S. EPA signed a construction completion report for the site in June 2000, and an open-house tour was conducted for interested citizens. The site is now in the operation and maintenance stage. Since groundwater treatment operations began, very good removal efficiency has usually been achieved for primary contaminants of concern, such as THF (95 to 99 percent ) prior to discharge. Initially, there were two to three very short-term episodes of process upset due to high/low water level alarm malfunction, but they were quickly repaired. After about 1.5 years of operations, organic strength of influent groundwater to be treated began a significant and steady rise. Accordingly, in August 2002 the groundwater treatment system was retrofitted, by converting an equalization to a second bioreactor tank. Since this change, discharge has again been achieving effluent limitations.
The WDNR prepared the first and second Five-Year Reviews for the CDCL site. The first CDCL Five-Year Review Report was signed by U.S. EPA on February 25, 2000. During the first five-year review, some groundwater quality trends at the site did not show progress consistent with goals established in the 1992 ROD. A second Five-Year Review Report was signed for the CDCL site by U.S. EPA on February 23, 2005. The primary technical finding during the second five-year review was that site remedies as executed continue to be protective of human health and the environment. However, there was room for improvement regarding the volume of groundwater which the site treatment system was capable of handling. The second Five Year Review also found that for a significant proportion of the time, the contaminated groundwater treatment system was operating within prescribed effluent limits. However, the significant organic strength of the influent groundwater generated by the extraction wells was such that extraction pumping rates had to be throttled back. During that time, a reduction of potential extraction volume/throughput was of concern to the agencies for two reasons: (a) the time to achieve eventual site groundwater remedial goals was extended. From the data compiled at that time, EPA and WDNR could not determine an overall groundwater data trend indicating progress toward groundwater remediation goals; and (b) there was a risk that the reduced pumping rate would fail to adequately capture the plume of contaminated groundwater, such that future off-site migration could be a possibility.
In November 2005, technical consultants for Waste Management of Wisconsin, Inc., the current owner and a former operator of the site preforming site cleanup with oversight from U.S. EPA and WDNR conducted pilot studies to dose contaminated groundwater "in-situ" with oxidizing agents prior to the water being pumped into the bioreactor treatment system. Results were evaluated to see if scale-up of this technique would be appropriate, in an effort to improve groundwater treatment efficiency. Initial results with the oxidizing agents were encouraging during early 2006. A report describing pilot work highlights was submitted in 2006. U.S. EPA and WDNR evaluated this report and determined that the scale-up was warranted.
On February 23, 2010, the third Five-Year Review Report was prepared and signed by U.S. EPA on February 23, 2010. The third Five-Year Review found that the remedy remains protective of human health and the environment in the short-term, and groundwater monitoring results showed significant progress towards health-based standards. The remedy is expected to be protective in the long-term when groundwater cleanup goals are achieved and instituional controls (ICs) are determined to be effective in the long-term. EPA is currently reviewing an IC Study-Plan to determine if ICs are functioning as intended.
ContactsRemedial Project Manager, U.S. EPA
Karen Mason-Smith (firstname.lastname@example.org)
Community Involvement Coordinator, U.S. EPA
AliasesCITY DISPOSAL CORP LDFL
CITY DSPL SAN LDFL
CITY DISPOSAL CORP LANDFILL