ARCHIVED REPORTS_XR0005244 - Laserfiche WebLink

Home Browse Search

Former Beacon Station No. 12474 January 17, 2006 Stockton California Quarterly Groundwater Monitoring/Remediation Status Repo oxygenate methyl-t-butyl ether (MTBE) by Environmental Protection Agency (EPA) Method 8260B. Groundwater Monitoring Results Depth-to-groundwater measurements were subtracted from the surveyed TOC elevations to calculate groundwater elevations. Groundwater elevation data, as summarized in Table 1, were used to construct the groundwater elevation contour map shown on Figure 2. The groundwater flow direction in the dispenser island area varied from northeastward to southeastward under a gradient of approximately 0.002. Groundwater analytical results are summarized in Table 1. Benzene concentration data were used to.construct an-isoconcentration.map.as.shown=on-Figure�3 Analytical-reports=are -- contained in Attachment C. Historical groundwater level and analytical data collected prior to 1998 are summarized in Tables 1 and 2 in Attachment D. Groundwater data indicate sizable reductions in analyte concentrations in source area wells MW-6, MW-12, VW-1 and VW-4 as a result of the implementation and continued operation of the VES and air sparge system. Vapor Extraction System Monitoring Construction for a vapor extraction system (VES) and an air sparging system was conducted in late 2004. The San Joaquin Valley Air Pollution Control District (APCD) issued a modified Authority to Construct permit in October 2004. Final equipment connections were made and final system preparations were conducted during first quarter 2005. Operation of • the VES was initiated on March 3, 2005. Final inspection of the VES was conducted by the APCD on May 19, 2005. Horizon submitted the Authority to Construct Inspection Report on June 21, 2005. The APCD issued Permit to Operate N-4941 on August 18, 2005. The location of the remediation system compound and underground piping is shown on Figure 4. The VES consists of a positive-displacement blower rated at 250 cubic feet per minute (cfm), a ThetmTech Vac 25 thermal/catalytic oxidizer and other associated equipment as shown on Figure 5. The VES is set up to extract vapors from vapor extraction wells VW-1 through VW-7. Soil vapor flow from each well is controlled by individual valves. The air sparging system consists of two 7.5 cfm compressors and other associated equipment as shown on Figure 5. The air sparge system is set up to sparge air to sparge well AS-1 and monitoring wells MW-2 and MW-12. Air sparging was initiated on June 27, 2005. Only one sparge compressor is in operation. The VES reporting period for this report _is S.eptember_27 to December 27, 2005. The VES operated for a total of approximately 62 days during this reporting period. Influent and effluent vapor samples were collected on October 10, November 4 and December 27, 20.05. Analytical reports are contained in Attachment C. Vapor extraction system data are summarized. in Table 2.. __Groundwater_-dissolved oxygen concentrations. and oxidation- reduction potential data are summarized in Table 3. •r 474gmr Q405 Project No. 1474.48 2 HORIZON ENVIRONMENTAL INC.