WORK PLANS_2006-2007 - Laserfiche WebLink

Home Browse Search

LFR Inc. extraction well network, installed in the area of the Site downgradient from Lincoln Center (wells GWE-18 through GWE-33). • Phase IV implemented in 2007: Operation air sparging followed by the blending of ozone in the air stream only after PCE concentrations have decreased to "acceptable" levels in the Historical Source Area. This system comprises 59 sparging wells (wells AS-1 through AS-59). As discussed in LFR's "NPDES Report for the Annual Period January 1 through December 31, 2006 Groundwater Extraction and Treatment System (WDR Order No. R5-2005-0144; NPDES Permit No. CA0084255)," dated January 30, 2007 (LFR 2007a), the GWETS continues to effectively mitigate downgradient migration of Hazardous Substances in both A- and B-groundwater zones at Lincoln Center since its installation. The GWETS is also removing a significant mass of volatile organic compounds (VOCs), thereby meeting the objective of the Phase I and III IRAs. During the 2006 reporting year, the GWETS processed approximately 76 million gallons of groundwater. The mass of PCE extracted by the GWETS during 2006 was 262 pounds. A total of 4,362 pounds of PCE has been removed from groundwater to date. Charts showing historical GWETS system performance, including flow rates, volumes, and PCE mass removal, are presented in the aforementioned report. As also discussed in the report, the Phase II SVETS IRA is effective in reducing concentrations of Hazardous Substances in vadose-zone soils beneath Lincoln Center. Through 2006, the SVE system also effectively removed a significant VOC mass of approximately 7,613 pounds of PCE from the soil vapor. Starting in late 2006 and finishing in early 2007, LFR constructed an air and ozone sparging system in accordance with the Phase IV IRA Detailed Plan. The system was started up in May 2007. Preliminary results show that the system is operating effectively; the system removes approximately 2 to 10 pounds of Hazardous Substances per day. Construction and startup of the Phase IV IRA will be documented in an upcoming report. 1.2 Proposed Phase V IRA Objectives As documented in LFR's "Results of Focused Membrane Interface Probe Investigation in the Vicinity of the Bank of Stockton, Lincoln Center, Stockton, California," dated March 29, 2007 ("the 2006 Bank of Stockton Investigation Report"; LFR 2007b), total Hazardous Substances, consisting primarily of PCE, were detected within groundwater in excess of 1,000 micrograms per liter (µg/1) in the vicinity of the Bank of Stockton. An isoconcentration contour map of total Hazardous Substances in A-zone groundwater is presented as Figure 3. As shown on this figure, the core of the A-zone plume downgradient from the eastern property boundary of Lincoln Center, consisting of Hazardous Substances in excess of 1,000 µg/1, is relatively narrow (approximately 350 feet wide), mirrors the extent of a sand channel identified in the 2006 investigation, and extends beneath the Bank of Stockton (see cross section B-B' presented on Figure 8). In addition, the highest concentrations of Hazardous Substances exist along a relatively Page 2 wp�PhV IRA-Sep07-Final-06750.dm:lfr