CMC Heartland Lite Yard Site
History and Cleanup
The CMC Heartland Lite Yard Site (CMC Site) is located in Minneapolis, Minnesota at the northwest intersection of Hiawatha Avenue and 28th Street South. Records show that Reade Manufacturing Company (Reade), an arsenical pesticide manufacturer, had leased and operated on the CMC Site for nearly twenty-five years from 1938 to 1963. The CMC Site was used for processing technical arsenic, a white powder, into sodium arsenate, a liquid, that was used as a general biocide along railroad lines. Lead arsenate may also have been produced at the CMC Site. US Borax sub-leased the CMC Site from 1963 to 1968, and manufactured, stored and shipped arsenic based pesticides for a portion of that period. Soil contamination was discovered in 1994 during reconstruction of the Hiawatha Avenue corridor.
Cleanup at the CMC Site began in the fall of 2004 and was completed in 2005. Soil was removed from a central hot spot on the site where the underlying soil was contaminated to a depth of about 25 feet. Additional soil was removed from shallower depths throughout the CMC Site to ensure that the top four feet of soil was not contaminated once the CMC Site had been re-developed.
Approximately 62,000 cubic yards of contaminated soil and debris were excavated from the CMC Site. For comparison, a typical dump truck can hold between 10 to 14 cubic yards of soil. The excavated soil and debris were disposed of at an industrial landfill in Minnesota and additional soil, contaminated with mercury (300 cubic yards), was disposed of at a landfill in Wisconsin.
For complete details please view the CMC Heartland Lite Yard Site web page.
South Minneapolis Residential Soil Contamination Site
Initial Residential Soil Sampling and Removal Actions
The Agency for Toxic Substances and Disease Registry (ATSDR), in conjunction with the Minnesota Department of Health (MDH), provided two Health Consultations dated April 8, 1999 and May 17, 2001 to the Minnesota Department of Agriculture (MDA). These Health Consultations expressed a concern about the possibility of highly contaminated dust being windblown off the CMC Site during historical site operations and noted that sampling had not been conducted in the residential area located adjacent to and northwest of the site.
In June 2001, the MDA and the MDH conducted a limited soil investigation in the residential yards west and northwest of the CMC Site to determine if elevated levels of arsenic were present. A follow-up investigation, using U.S. Environmental Protection Agency (EPA) data quality objectives, was conducted in September 2003. The results of these studies indicated that approximately 15 percent of the properties near the CMC site may have elevated levels of arsenic that could pose a health risk to children if ingested.
In January 2004, the MDA asked the EPA to review the data from the 2001 and 2003 MDA and MDH studies. In response to the studies, the EPA sampled over 400 residential properties and completed excavation work at 30 properties which exceeded the acute arsenic soil cleanup goal of 95 milligrams per kilogram, or parts per million, (ppm), of arsenic in soil. In 2005, the EPA sampled surface soils at over 600 residential properties, 13-day care centers, and four schools and excavated soil at 96 properties that exceeded the acute arsenic soil cleanup goal.
The EPA also completed an air dispersion computer model in 2005, which determined that arsenic contamination, from historic operations at the CMC Site, could have affected an area within a three-quarter mile radius of the property, potentially affecting 3,578 residential properties. This area would become known as the South Minneapolis Residential Soil Contamination Site (SMRSCS). In 2006, the EPA completed sampling at over 3500 residential properties. The EPA identified 206 properties that exceeded the acute arsenic soil cleanup goal of 95 ppm and by the end of 2008, 197 of those properties had been remediated. The remaining nine properties had unresolved access issues and were referred to EPA’s remedial cleanup program for follow-up.
Cleanup under EPA’s National Priority List
In September 2007 the EPA added the SMRSCS to the National Priority List of Superfund sites and completed a Remedial Investigation that included a baseline human health risk assessment. The assessment found that arsenic concentrations greater than 25 ppm could pose an unacceptable risk to residents, primarily from accidental ingestion of contaminated soil.
On September 5, 2008, a Record of Decision for the SMRSCS was signed and the final cleanup plan was approved. This plan required the removal of soil from residential yards where the arsenic levels in surface soil exceeded 25 ppm; this included approximately 487 properties. The EPA received funding for the cleanups through the American Reinvestment and Recovery Act. The EPA’s contractors began work in August 2009 and completed the cleanups on all properties where access was granted in September 2011. During this period 472 properties were excavated and restored. By 2021 all properties requiring sampling and/or remediation had granted access to the EPA and all necessary work was completed.
Cleanup of affected properties involved removing a foot of soil from grass and play areas and18 inches of soil in gardens and planting beds. If arsenic concentrations exceeded 95 ppm below the initial excavation, further excavation was completed until concentrations in remaining soil were below 95 ppm. Soil was not removed from beneath buildings or paved areas. Excavated properties were backfilled with clean soil and were either seeded or planted with sod. The excavated soil was disposed of in permitted landfills in Minnesota.
Soil Sampling Results
To receive soil sampling results for your residential property please contact:
U. S. Environmental Protection Agency (EPA)
Remedial Project Manager
Minnesota Department of Health (MDH)
MDA and MDH Resources