Technical Integrity / Collaboration / Exceptional Results
Projects

Sediment Remediation and Stormwater Source Control

At a former DDT manufacturing facility located within the Portland Harbor Superfund site on the Willamette River, Integral scientists and engineers have implemented source control measures (SCMs) in preparation for sediment remediation as part of ongoing assessment and cleanup. Integral staff completed a stormwater SCM-focused feasibility study and conceptual site model, and also identified and evaluated stormwater SCM alternatives.  Integral staff also helped negotiate National Pollutant Discharge Elimination System (NPDES) requirements with the Oregon Department of Environmental Quality (DEQ).

Integral staff completed the stormwater SCMs design, including key design elements: temporary capping for erosion control, decommissioning of existing stormwater facilities, rerouting of stormwater through new surface conveyances, and stormwater treatment utilizing a stormwater detention basin and sand filter. In addition to the design, Integral prepared a design bid package, assisted the Client with contractor selection, and provided construction quality assurance.

Integral’s design required tackling unique challenges, including the client’s desire to use only passive treatment technologies, agency requirements to treat DDT to previously unproven treatment levels (i.e., parts per trillion concentrations), and DEQ’s requirement to effectively manage and treat stormwater flows up to 13,000 gpm.  Five years of performance monitoring results have demonstrated that the stormwater SCMs are effective in reducing DDT concentrations in stormwater (>99 percent reduction); DDT was not detected in stormwater effluent discharge during the past water year.

In 2016, Integral received an engineering excellence award from the American Council of Engineering Companies for this stormwater source control project.  DEQ has also commended the collaborative effort; a video on DEQ’s web site features the successful work on the stormwater SCMs.

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