Construction Management at a Chromium-Impacted Residential Property

Client: State of Oregon

Location: Sherwood, Oregon

About the Site

A 40-acre tract of former pastureland was suspected to have been impacted by wastes from a nearby tannery that were used as a soil amendment. Beginning in the 1980s, the original site was subdivided into numerous smaller tax lots and redeveloped as low-density residential properties. Investigations of the site indicated that the soil was impacted by chromium at concentrations that posed a risk to the residents on the site. The state engaged MFA to cap one of the remaining tax lots with clean soil to prevent residents’ exposure.

Remediation Services 

MFA designed and provided construction oversight for a soil cap, which covered the impacted areas. Landscaped areas were also restored. This project was time-sensitive because the location of the major earthwork activities could be accessed only through a temporary access road. Approximately 374 tons of contaminated soil was excavated, transported off site, and disposed of at a permitted landfill. The area was restored to preconstruction conditions following completion of remedial activities.

The base of each excavation was surveyed to verify that the required excavation depth had been met. MFA reviewed post-excavation surveys and verified and approved the excavation depths prior to topsoil installation. Before placement of clean backfill, a high-visibility geotextile fabric was placed on the bottom of each excavation area.

Construction Reporting

MFA prepared daily construction progress reports that tracked daily activities, conditions, outstanding items, subcontractors, and on-site verbal communications. Daily reports were provided.

Project Outcomes

As MFA confirmed, construction conformed with the design, ensuring a smooth, transparent remediation process for the affected residents.