Removing 203,000 Tons of Contaminated Soil for a Major Interchange


The project area for the Highway 7 and Louisiana Interchange had a long history of heavy industrial and railroad-related activities that dated as far back as the early 1900s. Thorough environmental work, with coordination among multiple stakeholders, was necessary to make sure the project was in compliance.


The SEH environmental team conducted Phase I and II ESAs as well as environmental construction monitoring. SEH identified two Superfund Sites and a federal and state vapor intrusion investigation area during the Phase I ESA. The Phase II identified naphthalene, PAHs, petroleum compounds, calcium hydroxide, and metals as contaminants of concern for the project. SEH environmental staff worked closely with the design team to incorporate construction elements that addressed environmental concerns and helped determine staging requirements for soil and groundwater handling options. SEH worked with the MPCA and EPA to receive an approved Response Action Plan that detailed the proper procedures for handling contaminated soil and groundwater during construction. Construction monitoring was completed during all earthwork activities in 2013 through 2015 including the disposal of 203,000 tons of soil. SEH was the environmental liaison between the City, MnDOT, MPCA and EPA Region V throughout the project. Liability assurances were obtained for interested parties and, when the project was finished, no further action was required by the regulatory agencies.

Highway 7 and Louisiana Interchange

St. Louis Park, Minn.

City of St. Louis Park


  • Phase I ESA
  • Phase II ESA
  • Response Action Plan and Construction Contingency Plan
  • Project Manual Specifications for environmental work
  • Construction monitoring
  • Air monitoring and sampling
  • Construction dewatering treatment system monitoring
  • Soil screening
  • Soil disposal tracking
  • Confirmation soil sampling
  • General site activity documentation