Passive Soil Vapor Extraction - GSI Environmental Inc.

SRNL-STI-2009-00571Rev. 14.0 TECHNOLOGY PERFORMANCEThe performance of PSVE at several sites is summarized in the following section. In allcases, conditions at these sites were judged suitable for application of PSVE, either as astand-alone measure or following (or in conjunction with) ASVE. Performance wasassessed using most of the measures outlined in Section 5 of this document(concentration reductions, mass removal. etc.). Note that while the majority of the datais from applications using barometric pumping, a site where assisted PSVE using aMicroBlower device is also included.4.1 Metallurgical Laboratory (Metlab)4.1.1 Site DescriptionThe Metallurgical Laboratory (MetLab) waste unit is located at the Savannah River Site(SRS), within the A/M areas. PCE and TCE were the primary solvents used at the site, withhistoric releases leading to vadose zone soil impacts and the development of a soil gasplume. Nineteen vadose zone wells were installed across the source area of the Metlab in1996 and BaroBall TM devices were installed at the surface of each well casing to permitpassive soil vapor extraction via natural barometric pressure changes. Monitoring of wellvapor concentrations (PCE and TCE) began in June 1998 and continues to present day.Site characteristics that contributed to the selection of PSVE:• Vadose zone source is well-defined and present in deep, lithologically isolated strata• Need for cost-effective, low-maintenance treatment that protects the groundwater4.1.2 Results/Performance MetricsPerformance data for the Metlab is available through June 2005 (Riha, 2005b) and includestemporal concentration trends, mass removal rates, plume size, and cumulative massremoval, as summarized in Table 4.1.26 Enhanced Attenuation TechnologiesPassive Soil Vapor Extraction