During development of property once owned by a plant nursery, Town and Country Homes encountered large amounts of waste, including landscape materials, appliances, tires, construction and demolition debris, and auto parts.

Braun Intertec was retained to assess the extent of the debris, characterize it relative to potential contaminants and develop a response action plan. The site was immediately enrolled into the Minnesota Pollution Control Agency Voluntary Investigation and Cleanup Program (MPCA VICP), and Hennepin County solid waste personnel were notified of the situation.

Challenges

We began with a review of Minnesota Department of Agriculture files concerning a previous fire at the nursery in order to determine the types of pesticides that had been used and stored at the nursery. In addition, geophysical soil borings were reviewed to help determine the extent of the debris. Soil and groundwater samples were collected and analyzed.

Although low concentrations of several contaminants were identified at the site, the primary issue was one of how to cost-effectively dispose of over 30,000 cubic yards of waste-containing soils. County rules prohibited reusing the material onsite as fill or in berms. The material did not fully meet the definition of demolition debris and therefore could not be taken to a demolition landfill. Finally, costs of disposal at a sanitary landfill were very high.

Solutions

The problem was solved by passing the soils through a bar sieve to remove the majority of the debris. Larger items were removed manually prior to the sifting procedure. The waste was segregated into the following stockpiles for recycling and disposal: tires, metal, concrete and rock, wood, and other wastes such as plastic. The sifted soils were stockpiled pending analytical results, and confirmatory sampling was conducted at the base of the excavation.

Approval was given by the VIC Program and Hennepin County to move the sifted soils to an adjacent property that was owned and occupied by the nursery that had been responsible for the debris. The soils were placed beneath a parking lot and greenhouses during remodeling. A No Further Action determination was issued by the MPCA.