ARCHIVED REPORTS XR0006513 - Laserfiche WebLink

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8.0) VICINITY WATER SUPPLY WELLS The search of vicinity water wells performed by Western Geo-Engineers in 1998 identified no ' domestic or municipal water wells screened in this shallow aquifer within 900' of the site The closest water supply well screened in this aquifer is the J S Green, domestic supply well, located approximately 950' southeast of the site Please see Appendix A, Vicinity Wells, description and map ' 9.0) VAPOR EXTRACTION SYSTEM AND AIR SPARGING EFFECTIVENESS The vapor extraction system continued to work through the months of March, April, May and ' June, 1998 Shut downs occurred for quarterly monitoring (March 10 and 11, 1998) and for blower repair(April 13 through May 29, 1 998) The system operated a total of 18952 7 hours (790 days as of July 2, 1998) Vapor extraction total removed hydrocarbons, as gasoline using ' activated carbon as a control was 223 pounds and direct venting to atmosphere of 11 pound Previous vapor extraction removals were controlled by Thermal Oxidation and removed 74,849 pounds of gasoline range hydrocarbons ' Totals of gasolme range hydrocarbons removed by the vapor extraction system are as follows Thermal Oxidation destruction 74,849 pounds Carbon Adsorption 223 pounds Vent to atmosphere 11 pounds ' Total Removal 75,083ounds or approximately 12 013 gallons P PP Y � b Weekly bioventing of MW8 through MW 12 has been conducted by Lawrence Tank Testing Currently the groundwater is too high, no slotted casing is exposed above groundwater at MW12 to conduct bioventing As of June 22, 1998 the 2 hour once a week bioventing of MW7 and MW8 has removed a calculated S 38 pounds of gasoline range hydrocarbons and a total of 506 pounds of hydrocarbons as gasoline and CO? The average flow rate was 50 8 cfm, with a vapor stream consisting of TPH-g of 0 02 mg/1- and CO CO2 at 0 5% MW2 and MW13 are also used for airsparging comm n inns ( e c bon October 9, 1997) It is anticipated that sparging of these wells will introduce and make oxygen available for biodegradation of the down gradient wells MW8 and MW 12 Dissolved petroleum mass removal rates were effective during VES and sparging operations in that time period from 1990 to 1994 Petroleum mass removal attenuated significantly during 1994 in all tested wells Petroleum mass removal continued at significantly decreased rates from 1994 to 1998 Soil confirmation testing described in Section 4 0 of tins report fiirther supports that the SVE has 20