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HENNEPIN COUNTY
MINNEAPOLIS
Congressional District # 05
SOUTH MINNEAPOLIS RESIDENTIAL SOIL CONTAMINATION
EPA ID# MNN000509136Last Updated: November, 2008
Site Description
The South Minneapolis Residential Soil Contamination Site is located in Minneapolis, Hennepin County, Minnesota. The site encompasses an area of approximately 1,480 acres and has included over 3500 residential properties. While the site is largely residential it encompasses commercial, industrial and municipal properties. The site is located in close proximity to a former pesticide manufacturing plant property. The site is located in an Environmental Justice community. The former plant property was leased and operated by Reade Manufacturing, a generator of arsenic and/or lead arsenate-based grasshopper pesticide from 1938 through 1963. From 1963 through 1968, U.S. Borax sub-leased the parcel and stored and shipped product during that time. It is believed that during plant operations, the powder-like arsenic trioxide was blown off-site into the surrounding neighborhoods, impacting the soils. The former plant property was owned by the Chicago, Milwaukee, St. Paul & Pacific Railway from the 1880's through 1985. The Railway declared bankruptcy in 1985 and as a result the property was transfered to CMC Heartland Partners (CMC) on November 8, 1993. On August 15, 2005 2800 Hiawatha LLC bought the former plant property from CMC. The CMC Heartland Site property has been investigated and was remediated by CMC Heartland Partners in 2004 and 2005 under the States authorities. The property is now a light industrial/commercial warehouse facility.
Site Responsibility
The site is being addressed through federal and state actions.
Threats and Contaminants
Soils at the site are contaminated by arsenic compounds. The primary threat is to the residents through accidental ingestion of the contaminated soil. Low level threats exist through eating garden vegetables grown in the contaminated soil. Much lower threats exist through inhalation of the arsenic and absorption of the contamination through the skin. Everyone living in the area is serviced by municipal water so groundwater is not a current threat. The State of Minnesota is addressing the long-term groundwater threats through their cleanup programs.
Cleanup Progress
In 1994, the Minnesota Department of Transportation (MDOT) investigated the Hiawatha Avenue corridor for reconstruction, including the eastern-most part of the former plant property. MDOT discovered elevated levels of arsenic. With oversight from the Minnesota Department of Agriculture’s (MDA’s) Agricultural Voluntary Investigation and Cleanup (AgVIC) Program, several organizations, including MDOT, completed investigations of the surrounding area for arsenic contamination. In 1995, CMC Heartland Partners, completed soil investigations on its property, through the AgVIC Program. Arsenic levels in the surface soil were as high as 5200 parts per million (ppm). By 1996, the operator of the former plant property (an asphalt company) had covered much of the property with one to two feet of clean fill and crushed bituminous asphalt.
The Agency for Toxic Substances and Disease Registry (ATSDR) in conjunction with the Minnesota Department of Health (MDH) issued two Health Consultations in 1999 and 2001 which described public health hazards and recommendations to protect the public’s health. Risks were identified concerning arsenic in the soil that the public could come in contact with. Additionally, the Health Consultations expressed concern about the possibility of highly-contaminated dust being windblown off of the former plant property, affecting residences in the Phillips Neighborhood located just to the northwest of the property. The arsenic concentration ATSDR and MDH considered being an acute exposure was 110 ppm.
In 2001 and 2003, MDA and MDH performed limited soil investigations in residential yards. One hundred sixty-seven properties were sampled showing arsenic levels as high as 635 ppm. Ten properties had arsenic concentrations considered to be at or above the acute exposure level.
In 2004, MDA issued a Proposed Plan for Cleanup at the former plant property and requested assistance from EPA’s Removal Program to address the residential arsenic contamination. At the former plant Property, 62,000 cubic yards of soil were removed and sent to a landfill in Minnesota. The EPA’s Removal Program established an arsenic removal action number of 95 ppm. From May through October 2004, EPA sampled over 400 properties. Thirty properties exceeded the removal action number. By spring of 2005, EPA completed excavation work at those thirty properties. In August 2005, EPA’s Remedial Program sampled surface soils at over 600 residential properties, as well as at thirteen day care centers and four schools. Thirty-one more properties exceeded the removal action number. Twenty-four property cleanups were completed by November 2005. By winter 2006, EPA’s Removal Program had completed excavation and restoration at 95 residential properties.
In 2005, in an effort to identify areas for additional sampling, EPA ran an air dispersion model that estimated that arsenic contamination from the former plant property could potentially affect an area within a three-quarter mile radius of the property (3,578 residential properties). This area has been the study area for the site. In 2006, EPA’s Remedial Program completed sampling at over 3500 residential properties (all of the properties that granted access to EPA).
Based on the current data set within the established site boundary, a total of 206 properties had arsenic levels that exceeded the removal action number and required excavation and restoration. By the end of 2008, 196 of those properties had removal work completed. The remaining 10 properties have unresolved access issues and will be handled under the final Remedial Action cleanup plan for the site.
In November 2007 EPA completed the Remedial Investigation which included the baseline human health risk assessment. It found that arsenic concentrations greater than 25 parts per million would pose an unacceptable risk to the residents. The risk is primarily from accidental ingestion of contaminated soil. The risk assessment also determined that an acceptable preliminary remediation goal for arsenic would be between 16 parts per million (background arsenic concentrations for the area) and 25 parts per million.
Based on the RI sampling data EPA concluded that wind blown contamination from the former plant site may have contributed to the arsenic levels in the soil, but, only at very low levels within the 3/4 mile radius study area. The high levels of arsenic scattered throughout the study area, particularly at the outer edges of the sampling area, are not indicative of wind blown contamination being the sole contributor to arsenic levels in the area. If windblown from the plant site were the sole contributor, then a pattern of decreasing concentrations would be seen as you move away from the plant site. Decreasing patterns were seen in a few directions at some levels. However, the pattern of high levels scattered throughout the sampling area, or in some cases increasing concentrations, is more indicative of people also applying or bringing in material with high levels of arsenic on individual properties. Common fertilizers and pesticides contain such high levels of arsenic, as can coal ash, and pressure treated lumber. The Agency will therefore not expand the sampling area and will limit future cleanup work to properties within the current sampling area.
A Record of Decision for the site was signed on September 5, 2008. The final cleanup plan requires removing soil from residential yards with arsenic levels exceeding 25 mg/kg; approximately 512 properties. Workers will dig up a foot of soil from grass and play areas. Within gardens and planting beds, they will remove 18 inches. No soil will be removed where there are buildings or paved areas. Before cleanup begins, workers will do a survey so the yard can be restored – as much as practical – to the condition it was in before the cleanup. Soil samples will be taken after a foot of contaminated soil has been removed. If those samples show arsenic at levels above 95 mg/kg, workers will keep digging (to a maximum depth of 10 feet) until soil samples show that remaining soils do not exceed 95 mg/kg. Workers will then fill the yard with clean dirt and restore the property. Those most likely to come in contact with the deep soil are construction workers, and the risk assessment shows they would be safe even at levels higher than 95 mg/kg. Residents would also be safe from short-term exposure. EPA does not expect any long-term exposure to these levels. If complete excavation is not possible EPA would seek to have some form of legal notice or restriction placed on the property to prevent or control digging into any remaining contaminated soil.
EPA expects to complete the Remedial Design in early 2009. If funding is available, the final cleanups could begin in the summer of 2009. It is estimated to take approximately $20,000,000 and may take up to 2 1/2 to 3 years to, complete all of the cleanups.
Contacts
Remedial Project Manager, U.S. EPAtimothy prendiville (prendiville.timothy@epa.gov)
(312) 886-5122
Aliases
CMC HEARTLANDSOUTH MINNEAPOLIS RESIDENTIAL SOIL CONTAMINATION