After receiving an Environmental Protection Agency (EPA) Brownfields Assessment Grant for an area adjacent to its downtown core, the City of Casper began the process of returning its Old Yellowstone District into a destination for work and play

Since receiving an Environmental Protection Agency (EPA) Brownfields Assessment Grant in 2016, the City of Casper has been redeveloping the Old Yellowstone District, an area adjacent to the heart of downtown consisting of abandoned and blighted properties as well as underutilized commercial and industrial sites, with some contaminated by decades of industrial use.

Trihydro was selected as the environmental consultant to implement and administer the City of Casper’s EPA Brownfields Grant. First, Trihydro assisted the City of Casper in prioritizing properties in the Old Yellowstone District for assessment. Then, before starting work, Trihydro drafted the required Quality Assurance Project Plan and Sampling and Analysis Plan and received approval from EPA. Trihydro hosted a variety of collaborative public engagements, including open house sessions (click here for a link to the public flyer) and one-on-one meetings with property owners.

During grant implementation, Trihydro conducted 17 Phase I Environmental Site Assessments (ESAs) and 10 Phase II ESAs on a diverse portfolio of commercial and industrial properties, including a former railyard, historical service stations, an old ice factory, and a paint and auto body shop. Technical challenges included impacts associated with a large former refinery adjacent to the investigation area and a comingled perchloroethylene (PCE) plume adjacent to and within the Old Yellowstone District.

Additionally, Trihydro conducted a Phase I ESA for the State of Wyoming on five parcels containing a total of nine buildings, each scheduled for demolition to clear the property for the construction of a new state office building. Phase I ESA results indicated that the buildings likely contained asbestos-containing material (ACM). As part of a Phase II ESA, Trihydro inspected the buildings and identified ACM for abatement. The Phase II ESA also included a vapor intrusion study to determine if existing groundwater impacts on the property would cause indoor air quality concerns for the future office building. In addition, Trihydro collected radon measurements from soil gas to determine if radon concentrations would be predicted to exceed EPA action levels. The Phase II ESA vapor intrusion and radon assessment results helped the State of Wyoming select an adequate vapor intrusion barrier for the 110,000-square-foot office building.

Altogether, the project team assessed 34 acres within the grant period and under the grant budget (click here for a link to a local news story). Phase I ESAs conducted under the grant assisted in the sale of three commercial properties in the Old Yellowstone District, helping previously unused properties re-enter the tax base and revitalizing the area for community use. After completing Phase I and II ESAs on over 9 acres, the State of Wyoming completed the construction of the Thyra Thomson State Office Building in 2021. The office building is located in the heart of the Old Yellowstone District and will serve as an anchor for redevelopment in the area.

"Trihydro is one of the best consultants we have had the opportunity to work with. Very professional and thorough…and their public outreach marketing materials are outstanding.” – Craig Collins, City Planner, City of Casper

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