Ecosystem services consideration in the remediation process for contaminated sites.

In 2009, the U.S. Environmental Protection Agency's Science Advisory Board recommended activities to advance consideration of ecosystem services (ES) to enhance existing remediation and redevelopment processes in the U.S. This article examines advancements in the decade since, focusing on providing those involved in cleanup of contaminated sites a basic understanding of ES concepts and guidelines for considering ES at cleanup sites using a new, four-step transferable framework. Descriptions, including activities for site teams and case study applications of ES tools, are presented for each step: (1) identify site-specific ES; (2) quantify relevant ES; (3) examine how cleanup activities affect ES; and (4) identify, select, and implement solutions (e.g., Best Management Practices). The goal of this article is to provide site cleanup stakeholders, including project managers, contractors, and site responsible parties, with a stronger foundation and shared understanding to consider ES during the cleanup process for their given site. Anticipated outcomes include identifying ES benefits to inform management and tradeoff analyses, a reduction in unintended impacts on ES during site operations, and attention to developing a robust suite of ES relevant for site reuse.

Changes in contaminant mass discharge from DNAPL source mass depletion: evaluation at two field sites.

Changes in contaminant fluxes resulting from aggressive remediation of dense nonaqueous phase liquid (DNAPL) source zone were investigated at two sites, one at Hill Air Force Base (AFB), Utah, and the other at Ft. Lewis Military Reservation, Washington. Passive Flux Meters (PFM) and a variation of the Integral Pumping Test (IPT) were used to measure fluxes in ten wells installed along a transect down-gradient of the trichloroethylene (TCE) source zone, and perpendicular to the mean groundwater flow direction. At both sites, groundwater and contaminant fluxes were measured before and after the source-zone treatment. The measured contaminant fluxes (J; ML(-2)T(-1)) were integrated across the well transect to estimate contaminant mass discharge (M(D); MT(-1)) from the source zone. Estimated M(D) before source treatment, based on both PFM and IPT methods, were approximately 76 g/day for TCE at the Hill AFB site; and approximately 640 g/day for TCE, and approximately 206 g/day for cis-dichloroethylene (DCE) at the Ft. Lewis site. TCE flux measurements made 1 year after source treatment at the Hill AFB site decreased to approximately 5 g/day. On the other hand, increased fluxes of DCE, a degradation byproduct of TCE, in tests subsequent to remediation at the Hill AFB site suggest enhanced microbial degradation after surfactant flooding. At the Ft. Lewis site, TCE mass discharge rates subsequent to remediation decreased to approximately 3 g/day for TCE and approximately 3 g/day for DCE approximately 1.8 years after remediation. At both field sites, PFM and IPT approaches provided comparable results for contaminant mass discharge rates, and show significant reductions (>90%) in TCE mass discharge as a result of DNAPL mass depletion from the source zone.