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Cleanup of High-Profile Legacy Contamination at CDOT Headquarters to Facilitate Redevelopment

CDOT, Kentro Group, and ARCADIS – Denver, CO

Cleanup of High-Profile Legacy Contamination Set to Revitalize Former CDOT Headquarters Through Private-Public Partnership 

Through a unique private-public partnership between the Colorado Department of Transportation (CDOT) and private developer Kentro Group (Kentro), Weaver Consultants Group’s (WCG) Remediation Services team was retained to provide turnkey remediation, future site planning design, and regulatory interaction and management associated with revitalization of CDOT’s former headquarters facility into a mixed-use development in a highly desirable area near the center of Denver, CO.

The former CDOT headquarters facility was a multipurpose complex housing administrative office and a Material Testing Laboratory (MTL) for analyzing chemicals, soil, foundations, paint, cement, asphalt, and concrete. The MTL operated from the late 1950s to 2018, resulting in soil and groundwater impacts containing 1,1,1-Trichloroethane (1,1,1-TCA), Trichloroethene (TCE), Methylene Chloride (DCM), 1,4-Dioxane, and petroleum distillates on-site, and areas originally extending over 1-mile downgradient. In 1993, on behalf of CDOT, under a State of Colorado Corrective Action Order on Consent, soil, groundwater, surface water, and Indoor Air (IA) environmental investigation activities were completed. Remedial activities were implemented in 1994. WCG’s management of this project was one of the first IA-focused investigations and remediation programs, leading to the development of the Johnson-Ettinger IA model.

Because of WCG’s multiple award-winning brownfield development experiences working with national developers to create unique revitalization solutions for environmentally impaired US properties and its reputation of partnering with regulatory stakeholders, CDOT engaged WCG to facilitate the successful transaction of the property. Under an accelerated timeline, WCG teamed with CDOT and Kentro to optimize the planned design and develop a synergistic remedial program focused on facilitating future redevelopment. Key actions included:

  • Meeting with key stakeholders to understand respective goals/challenges and present alternative concepts, limitations, and approaches required to maintain the desired value proposition.
  • Developing and negotiating a unique regulatory solution to expedite regulatory closure (3-months) of 80+% of the property to support funding the transaction through traditional financing.
  • Developing and implementing a synergistic in-situ remediation program that supports and aligns with the property development plan schedule. This plan included locating a park and required stormwater management infrastructure within the remediation area in addition to institutional controls to address potential vapor migration in nearby structures.

Based on investigation findings and successful negotiations with the Colorado Department of Public Health and Environment, WCG obtained No Further Action approvals in 2018 on behalf of CDOT. Most of the property was approved to facilitate the stakeholder’s vision of creating a center that re-energizes this section of Southwest Denver and establishes a place where community members live, shop, eat, and entertain. The new development at the former CDOT facility is projected to include over 800 residential units, of which 150 will be affordable, and provide 200 permanent jobs through 150,000-sq.-ft of commercial space. In 2019, property buildings were raised, and hydraulically fractured wells were installed to target and expedite remediation of recalcitrant contamination in fractured bedrock to meet the redevelopment timeline. Subsequent monitoring of the in-situ remediation program has demonstrated continued success in reducing contaminant mass, terminating offsite remediation and IA monitoring and mitigation, and further reducing the remedial timeline through ongoing optimization and efficiency.