The Union Flats site was formerly used for numerous industrial operations, including the Northwestern Blaugas Company, a manufacturer of compressed/liquefied oil gas and purified phenols through extraction from wood tar. Redevelopment activities for the Site included demolition of the existing Site structures and improvements and construction of a four-story apartment complex, including underground parking, with approximately 217 units of affordable housing and associated interior and exterior common amenity spaces.
Braun Intertec completed environmental assessment activities of three contiguous parcels approximately 3.37 acres in size, including multiple rounds of subsurface investigations to identify, characterize and delineate the extent of petroleum and non-petroleum soil, groundwater and soil vapor impacts. Investigation activities also included identification and quantification of asbestos-containing materials (ACM) and other hazardous materials in the former buildings prior to demolition.
Our environmental consulting professionals developed a response action plan and construction contingency plan (RAP/CCP), and plans/specifications to address the identified soil, groundwater and soil vapor impacts. Response actions included the removal of approximately 34,000 tons of contaminated soil and the installation of a sub-slab vapor intrusion mitigation system for the new apartment complex. In addition, we prepared specifications for the abatement of ACM and the removal of hazardous materials from the former buildings.
As part of the project, Braun Intertec assisted the developer with obtaining regulatory liability assurances and approvals from the Minnesota Pollution Control Agency (MPCA) Voluntary Investigation and Cleanup (VIC) and Petroleum Brownfields Programs. In addition, we prepared applications for environmental cleanup grants from several funding sources and assisted with grant management.
Challenges and Solutions:
- Obtaining sufficient grant funding to help offset the significant environmental remediation costs.
- Excavation of contaminated fill soil during winter/frozen soil conditions.
- 发现埋入地下的混凝土罐拱顶containing several thousand gallons of petroleum and phenol impacted liquid, sludge and debris.
- Remediation included pumping out the liquid and sludge, removal and disposal of the debris, cleaning and disposal of the tank from the vault and segregation/disposal of the stained/impacted concrete vault floor and walls.
If you have any questions about this project or environmental considerations for affordable housing development, please contact us.