Case Study: Puget Sound Park Uses Tech Combo for Cleanup
With combined chemical and biological treatment, formerly contaminated land is added to Bremerton’s Evergreen Park in Washington.
Using a combination of in-situ chemical oxidation and enhanced bioremediation technologies developed by Regenesis of San Clemente, Calif., Washington-based environmental firm Parametrix Inc. completed the final cleanup of a 1.4-acre brownfield site that is slated to become part of Evergreen Park.
David Dinkuhn, P.E., Parametrix’ project manager, described the remediation process as “a solid success.” Noting that this approach was “significantly less expensive than typical dig and haul,” Dinkuhn said. “The site is now positioned for development as a park as we enter the long-term monitoring phase.”
The Evergreen Park Expansion, which earned the Puget Sound Regional Council’s Vision 2020 award for the city of Bremerton, will anchor the northern end of the planned Bremerton Park to Park Loop Trail, designed to connect the downtown Harborside District and Kitsap Transit bus/ferry terminal with local neighborhoods.
The 1.4-acre waterfront site served as a bulk petroleum tank farm from the end of World War II until the structures were taken down in 1988, leaving creosote pilings and concrete debris in the aquatic near-shore habitat as well as gasoline, diesel, and oil contamination in soil, groundwater, and marine sediments. Chevron Corporation, the site owner, operated a soil vapor extraction system that removed approximately 195,000 pounds of hydrocarbons (floating product and soil contamination) from the site between 1990 and 1994 but later sampling showed high concentrations of contaminant still present throughout the site.
A total of 3,870 cubic yards of contaminated soil was located within a smear zone at 8 to 14 feet below ground surface,” Dinkuhn explained. “Identifying the best remedial technology was difficult due to the high concentrations of [total petroleum hydrocarbons as gasoline] (5,100 mg/kg) and [total petroleum hydrocarbons as diesel] (6,900 mg/kg) and the site’s sensitive bayside location. The approach we selected, which proved very successful, was to reduce the soil contaminant mass in-place."
The contractor, Doyle & Lang LLC of Beaverton, Mich., completed the job in 13 working days, including both the initial treatment and retreatment of 5,000 square feet required to bring the entire site to the required cleanup level of 75 percent reduction of pre-treatment concentration levels. The team treated the site with a combined application of RegenOx® and ORC Advanced® products.
In the park, restored beach areas will be accessible by strollers, walkers, and kayakers, with trails for walking and biking. The new park area will also feature a multi-use, elevated amphitheater for public, private, arts, music, education, and community events.