SOUTH MINNEAPOLIS RESIDENTIAL SOIL CONTAMINATION
On this page:
- What Is Being Done to Clean Up the Site?
- What Is the Current Site Status?
- EPA’s Involvement at the Site
- Sampling and Monitoring
- Operable Units (opens new page)
- Cleanup Progress (opens new page)
The CMC Heartland Partners Lite Yard site is at the northwest corner of Hiawatha Avenue and 28th Street on the eastern edge of the Phillips neighborhood. The company made and stored pesticides there from 1938 to 1968. High levels of arsenic were found in soil and ground water at the site in 1994, during a project to rebuild the Hiawatha Avenue corridor. State health and environmental officials determined the contamination came from the CMC Heartland Partners Lite Yard. In September 2007, EPA added the South Minneapolis Residential Soil Contamination Site to its National Priorities List. The cleanup’s final phase ran from 2009 to 2011. In this phase, ARRA funds helped EPA finish its work ahead of schedule and make the South Minneapolis area safer for residents.
For a decade, the wind blew arsenic contamination from a pesticide plant operating at the CMC Heartland Partners Lite Yard property into the historic Phillips, Longfellow and Powderhorn neighborhoods in south Minneapolis. People there didn't learn until the mid-1990s that their families might be at risk from the arsenic. State and federal government cooperation, and a boost from the American Recovery and Reinvestment Act, turned this diverse neighborhood into a cleaner, safer place. It is an ARRA success story.
It was the $20 million in ARRA funds that helped the U. S. Environmental Protection Agency complete the residential cleanup a year ahead of schedule. EPA used ARRA and other funds to clean up more than 600 properties with unsafe levels of arsenic. EPA removed over 50,000 tons of contaminated soil.
What Is Being Done to Clean Up the Site?
The site is being addressed through state and federal actions.
EPA is conducting the first five-year review of the site’s remedy and plans to complete it in 2014. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents.
What Is the Current Site Status?
Between 2004 and the fall of 2008, EPA conducted soil excavation and off-site disposal as part of a removal action at 196 properties with arsenic levels above the removal action level. The site’s long-term cleanup plan, selected by EPA in 2008, addressed about 500 more properties. While arsenic levels at these properties were not immediately dangerous, the levels present still posed a long-term health threat to the residents.
The cleanup’s final phase ran from 2009 to 2011. American Revitalization and Recovery Act (ARRA) funding helped EPA complete the residential cleanups a year ahead of schedule. EPA used ARRA and other funds to clean up more than 600 properties with unsafe levels of arsenic. EPA removed over 50,000 tons of contaminated soil.
EPA’s Involvement at the Site
The South Minneapolis Residential Soil Contamination ("South Minn") 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 contains commercial, industrial, and municipal properties.
The South Minn site is located in close proximity to a former pesticide manufacturing plant. The pesticide 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, which resulted in contaminated soils.
The pesticide plant property was owned by the Chicago, Milwaukee, St. Paul & Pacific Railway from the 1880s through 1985. After the railroad declared bankruptcy in 1985, the property was transfered to CMC Heartland Partners (CMC) in November 1993. On August 15, 2005, CMC sold the property to 2800 Hiawatha LLC. The CMC Heartland Partners Lite Yard site property has been investigated and it was cleaned up 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.
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 for the site that described public health hazards and contained recommendations to protect public 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 established an arsenic removal action level of 95 ppm for the neighborhoods. In 2004, EPA sampled over 400 properties and completed excavation work at thirty properties which exceeded the removal action level. In 2005, EPA sampled surface soils at over 600 residential properties, 13 day care centers, and four schools and excavated 95 properties that 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 completed sampling at over 3500 residential properties (all of the properties that had 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 EPAs remedial cleanup program for additional followup.
In 2007 EPA completed a Remedial Investigation (RI) at the South Minn site that 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 contamination from the plant site was 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 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 required 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 the site. EPAs contractors began work at the site in August 2009 and completed it 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 landfills in Minnesota.
By the end of the cleanup work in September 2011, 472 properties had been excavated and restored, which represents 97% of the properties at which EPA believes cleanup is needed. 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 property permits 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.
Sampling and Monitoring
During cleanup, a site can be divided into a number of distinct areas depending on its complexity. These areas, called operable units (OUs), may address geographic areas, specific problems, or areas where a specific action is required. Examples of typical operable units include construction of a groundwater pump and treatment system or construction of a cap over a landfill.