Congressional District # 05
SOUTH MINNEAPOLIS RESIDENTIAL SOIL CONTAMINATIONEPA ID# MNN000509136
Last Updated: November, 2011
The South Minneapolis Residential Soil Contamination site is located in the city of Minneapolis, Hennepin County, Minnesota. The site covers an area of approximately 1,480 acres and soil sampling has been conducted at more than 3500 residential properties in an ethnically and economically diverse community. While the area is largely residential, it also encompasses commercial, industrial, and municipal properties.
The site is located in close proximity to a former pesticide manufacturing plant. The former plant property was leased and operated by Reade Manufacturing, which made arsenic and/or lead arsenate-based grasshopper pesticides from 1938 through 1963. From 1963 through 1968, U.S. Borax sub-leased the parcel and stored and shipped pesticide products during that time. It is believed that during plant operations, the powder-like arsenic trioxide was periodically blown by the wind off site into the surrounding neighborhoods and impacting the surface 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 Partners Lite Yard Site property has been investigated and was remediated by CMC Heartland Partners in 2004 and 2005 under the oversight of the Minnesota Department of Agriculture (MDA) and other state authorities. The property is now in re-use by a light industrial/commercial facility.
The site is being addressed through federal and state actions.
Threats and Contaminants
Residential soils at the site were contaminated by arsenic compounds. The primary health threat to the residents was caused by long-term accidental ingestion of the contaminated soil, such as by eating root vegetables which were grown in contaminated soil and not sufficiently washed or through children digging in soil during play and then eating with dirty hands. A small threat also existed through inhalation of the arsenic and absorption of the contamination through the skin. Everyone living in the area is serviced by municipal water; therefore, groundwater contamination does not present a current health threat. The state of Minnesota is addressing the potential long-term groundwater health threat through its cleanup programs.
In 1994, the Minnesota Department of Transportation (MDOT) investigated the Hiawatha Avenue corridor for road reconstruction and discovered elevated levels of arsenic on the eastern-most part of the former plant property. With oversight from the 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 found to be 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 and 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. EPA’s Removal Program established an arsenic removal action level of 95 ppm. In 2004, EPA sampled over 400 properties and completed excavation work at thirty properties which exceeded the removal action level. In 2005, EPA’s Remedial Program sampled surface soils at over 600 residential properties, 13 day care centers and four schools and excavated 95 properties which exceeded the removal action level.
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 have affected an area within a three-quarter mile radius of the property (3,578 residential properties). In 2006, EPA’s Remedial Program completed sampling at over 3500 residential properties (all of the properties that granted access to EPA) within this area.
Based on the final 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, 197 of those properties had removal work completed. The remaining 9 properties had unresolved access issues and were referred to EPA's remedial program for additional followup.
In 2007 EPA completed the Remedial Investigation IRI) which included the baseline human health risk assessment. It found that arsenic concentrations greater than 25 parts per million could pose an unacceptable risk to the residents, 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 three-quarter-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 one moved 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 unknowingly bringing in material with a high levels of arsenic on individual properties. Common fertilizers and pesticides contain such high levels of arsenic, as does coal ash and pressure treated lumber. The Agency therefore decided not to expand the sampling area and to limit cleanup work to properties within the 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 487 properties. In 2009 EPA received funding through the American Reinvestment and Recovery Act to fund the cleanup work at this site. EPA's contractors began work at the site in August 2009 and completed in September 2011. To clean up a property, workers dug up a foot of soil from grass and play areas. Within gardens and planting beds, they removed 18 inches of soil. No soil was removed from beneath buildings or paved areas. Soil samples were taken after a foot of contaminated soil had been removed. If those samples showed arsenic at levels above 95 mg/kg, workers kept digging until soil samples showed that remaining soils did not exceed 95 mg/kg. (Those most likely to come in contact with the deep soil are construction workers, and the risk assessment shows they will be safe even at levels higher than 95 mg/kg. Residents will also be safe from short-term exposure at these levels. EPA does not expect any long-term exposure to these levels.) Workers then filled the yard with clean dirt and restored the property. The contaminated soil was taken to permitted ed landfills in Minnesota.
By the end of construction for the site in September 2011, 472 properties had been excavated and restored during this final remedial phase of the cleanup, which represents 97% of the properties at which EPA believes cleanup is needed at the Site. Owners of the remaining 3% of properties either chose not to have the cleanup conducted or did not respond to EPA requests for access, which were made over a number of years and in multiple languages. Properties which had the cleanup conducted are available for unlimited use and unrestricted exposure. Property owners are required by City of Minneapolis Code of Ordinances Section 248.30(a)(5) to disclose to potential buyers environmental testing performed on the property by or under the direction of EPA or other governmental agencies. For properties where cleanup was needed, but for which access was not granted, the City of Minneapolis has assured that rental properties will not be issued. EPA expects these measures will encourage the property owners to perform the necessary cleanup, at their own expense, when they wish to sell the property or attain a rental permit. No additional remedial action is planned for this Site. Since hazardous substances remain at the site at some properties where access for cleanup was not granted, Five Year Reviews will be performed at the Site to evaluate the protectiveness of institutional controls.
Success StoryOverall at the Site, through both removal and remedial actions, about 665 residential properties were cleaned up and made safe for residents and the neighborhood, including gardening and children playing. This work involved several years of intensive community involvement, with preparations including materials in a variety of languages and contacts by a variety of means in order to meet the needs of this environmental justice community.
The residential area which makes up the South Minneapolis Residential Soil Cleanup site is an ethnically and economically diverse community. Public outreach materials have been prepared in multiple languages, including Somali, Vietnamese, Hmong, Spanish, and English. Spanish-speaking staff members have been an important part of EPA's communications effort with homeowners and translators for other languages were used as needed. The State of Minnestoa's Department of Agriculture and Department of Health, the City of Minneapolis, and a variety of community neighborhood groups assisted with outreach to the community and helped encourage residents to participate in the cleanup.
ContactsRemedial Project Manager, U.S. EPA
howard caine (firstname.lastname@example.org)
SOUTH MINNEAPOLIS RESIDENTIAL SOIL CONTAMINATION