This spring, a series of environmental site assessments were performed for a property at 3344 Highway 149/Dodd Road (Eagan Office Warehouse) to investigate soil conditions, at the direction of the property owner.
Soil samples in each of the assessments returned lead results in excess of the commercial/industrial soil reference value (SRV) and residential SRV. SRVs are a screening tool that may be used to evaluate potential human health risks from soil exposure.
As a result, a response action plan was written by a third-party environmental consultant hired by the property owner in May 2020 detailing excavation work to be performed on the site. Based on the results of the remedial investigation, approximately 0.4 acres of soil to a depth of 6 inches was proposed for excavation. Excavation of the lead-impacted soils began in May 2020 and was completed in June 2020. In May 2020, the 3344 Highway 149/Dodd Road property entered into the MPCA’s voluntary cleanup program.
Gopher Resource is a manufacturing facility that produces refined alloys through the smelting and refining of spent lead-acid batteries and other lead bearing materials. Gopher Resource has an active Resource Conservation and Recovery Act (RCRA) Hazardous Waste Storage Facility Permit. A RCRA permit is a legally binding document that establishes the waste management activities a facility can conduct and the conditions under which it can conduct them and allows a facility to treat, store, or dispose of hazardous waste.
Emissions at the Gopher Resource facility, including lead emissions, are regulated under an air emissions permit, which is a legal document that describes the requirements that a facility must meet for federal and state air quality regulations. Any facility that emits air pollutants above certain levels is required to have an air permit.
A 1992 study by Dakota County evaluated soil near the Gopher Resource facility to determine if there were any historic impacts of lead to soil in the area. Four soil samples were collected from the Burr Oaks neighborhood northeast of the Gopher Resource facility. Lead values from these soil samples ranged from 58 milligrams per kilogram (mg/kg) to 210 mg/kg and were all below the lead residential/recreational soil reference value (SRV) of 300 mg/kg.
Because lead-impacted soils were found at the 3344 Highway 149/Dodd Road property above the residential/recreational SRVs in areas adjacent to the Burr Oaks neighborhood, Gopher Resource sampled residential soils in the neighborhood for lead. A work plan was developed by Gopher Resource and approved by the MPCA that detailed the work to be completed. Soil samples were collected in July 2020 from the residential properties that are directly adjacent to the 3344 Highway 149/Dodd Road property by a third-party environmental consultant hired by Gopher Resource.
A total of 113 samples from 13 residential properties were collected by the environmental consultant using a grid layout for sample collection. Four samples were collected from each grid and composited into one sample for laboratory analysis at Pace Analytical, an independent laboratory. If samples were not able to be collected on the proposed grid due to dense vegetation or pavement, additional sample grids were added to ensure each property would have samples collected from at least one grid row.
Lead levels in all samples collected were less than the residential/recreational soil reference value of 300 mg/kg. The concentrations ranged from 7.5 to 238 mg/kg and were typical of background levels in the Twin Cities metro. The results of this screening assessment were consistent with the 1992 study by Dakota County.
Because the lead level in soil in all of the samples was below the residential/recreational soil reference value of 300 mg/kg, no cleanup or excavation of soil is required.
For more information:
Minnesota Pollution Control Agency