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NPL Site Narrative for Madison Metropolitan Sewerage District
MADISON METROPOLITAN SEWERAGE DISTRICT LAGOONS
Blooming Grove, Wisconsin
Federal Register Notice: February 21, 1990Conditions at proposal (June 24, 1988): The Madison Metropolitan Sewerage District (MMSD) Lagoons cover 135 acres in Blooming Grove, Dane County, Wisconsin. The City of Madison Water Utility has been depositing sludge from its Nine Springs Sewer Treatment Plant in the two lagoons since 1942. In 1970, a dike broke, releasing liquids from the lagoons into an old effluent channel that runs north to Nine Springs Creek, which empties into the Yahara River; a large number of fish were killed. A second dike broke in 1973.
In December 1982, MMSD detected PCBs -- as high as 138 parts per million (ppm) in some samples -- in the lagoons, which contain almost 50,000 dry tons of PCB-contaminated sludge. The lagoons are in a lowland area bordered on two sides by 1,000 acres of wetland. Subsurface deposits are permeable. Thus, contaminants in the lagoon have the potential to move into ground water. An estimated 94,000 people obtain drinking water from municipal wells within 3 miles of the site. Madison City Well #5 is 1,000 feet to the west of the lagoons.
Status (February 21, 1990): MMSD is monitoring all dikes for stability in accordance with its permit under the Wisconsin Pollutant Discharge Elimination System. No signs of dike failure have been detected to date.
MMSD is managing the sludge based on PCB levels. Sludge below 50 ppm is spread on agricultural lands during the growing season. Sludge above 50 ppm remains in place; monitoring indicates PCB levels are dropping slightly. MMSD is conducting tests through the University of Wisconsin to determine the fate of PCBs in the soil when sludge with 50 ppm or more of PCBs is spread on agricultural land. The Wisconsin Department of Natural Resources and EPA review test data as they become available.
For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737.