Transforming Contaminated Ground in the Lillie Redevelopment Project

Challenge

As the site of a former gas station and newspaper publisher, the Lillie Redevelopment project in North St. Paul, Minnesota, requires careful attention to identifying and cleaning up contaminants within and around the former building, before redeveloping it into a commercial property. Before demolition, asbestos removal is mandatory, and appropriate disposal of petroleum-affected groundwater and soil is crucial. Alongside these challenges, the project faces further hurdles posed by geotechnical conditions; in addition to dealing with uncontrolled fill soil, the native soil at the site proved unsuitable for construction purposes due to its structural limitations.

The City views the redevelopment as a key component in revitalizing the downtown area, making it necessary to address the underutilized buildings in that vicinity.

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Solution

TJL Development hired SEH to provide multi-disciplined services to support the redevelopment of the contaminated brownfield site for use as an 82-unit apartment complex. 

SEH completed various environmental assessments and surveys following American Society for Testing Materials International (ASTM) and Minnesota Pollution Control Agency (MPCA) requirements for the Lillie Redevelopment project. These assessments include a Phase I ESA, a Phase II ESA, soil vapor investigations, and asbestos and hazardous building materials surveys. SEH also conducted a geotechnical assessment and prepared a Response Action Plan (RAP) for the project and closely coordinated response actions with geotechnical recommendations.  

The SEH team proposed using rammed aggregate piers on-site instead of removing and replacing unsuitable soils to manage the softer native soils, which were also contaminated. This approach will significantly reduce landfilling and dewatering costs.  

To protect the safety of future residents and workers, a vapor mitigation system also had to be established as a precautionary measure to prevent the infiltration of petroleum vapors into the new building.

To offset the cleanup costs and on behalf of the City, SEH applied for and received $422,020 in grants from the Minnesota Department of Employment and Economic Development (DEED), the Metropolitan Council, and Ramsey County. In addition, SEH applied for a DEED Redevelopment Grant to cover the expenses of infrastructure, demolition, and geotechnical soil correction, receiving over $169,000.  

Additionally, SEH obtained a No Association Determination and secured RAP approval on behalf of TJL Development from the MPCA Voluntary Investigation and Cleanup and Petroleum Brownfields Programs.  

Construction is set to begin in the Summer of 2023, and upon completion, the project will introduce 82 new housing units and generate an estimated increase of $279,000 in property taxes.