Page 30 - Trihydro Sustainability Report

Use of in-situ bioremediation and solar-powered pumping system to treat a

former municipal solid waste site

NORTHEAST NEBRASKA

In 2015, Trihydro assumed responsibility for implementation and effectiveness monitoring of corrective
actions at a closed landfill site in Nebraska. This high-profile project site is a former municipal solid
waste site, and both groundwater and soil are impacted. The existing corrective action system consisted
of groundwater pump-and-treat, in-situ aerobic bioremediation, and periodic in-situ chemical oxidant
injection. Remediation activities at this site are further complicated by the site’s remoteness, leading to a
lack of utility access to power and sewer: any pumped groundwater was being transported by truck to an
offsite disposal facility.

After a thorough review of the existing corrective action system, Trihydro executed a new corrective action
plan which excluded groundwater pump-and-treat. The new plan instead included in-situ bioremediation
using emulsified vegetable oil (EVO) in the source area and air sparging in the downgradient dissolved
plume area. Much of the existing infrastructure was retained, including solar powered pumps used in the
previous groundwater pump-and-treat system.

Preliminary results indicate that EVO injections have been positively affecting chlorinated compound
concentrations. Additionally, the change to a solar powered in-situ system from the previous solar
pumping and off-site disposal system resulted in 200 fewer truck trips from the site each year, resulting in
the elimination of about 6,000 miles of truck traffic annually.

26 HEALTHY ENVIRONMENT