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i1995 . Ground water gradient shows a relatively flat flow to the <br /> east, with a high mound at MW3 (probable residual high in ground <br /> water caused from the vapor extraction at this well) <br /> MW-8 BIO-VENTING OXYGEN TRANSFER <br /> On October 26, 1994 , a bio-venting source test was performed on <br /> MW-8 The purpose of this test was to evaluate the benefit of <br /> Performing a once a week evacuation of the well to enhance oxygen <br /> transfer and remove residual CO2 <br /> Presently the vapor extraction system at Former Regal Station <br /> 603 , PTO # N-1090-1-0, is only having only limited effect on the <br /> leading edge of the dissolved gasoline range plume that has <br /> traveled east from the site, across Pacific Avenue Two sources <br /> tests, of two hours each, were conducted on MW8 The well is <br /> near the leading edge of the plume and results indicate that a <br /> two hour vacuum extraction once a week will help control the <br /> migration of the plume and will enhance biodegradation by <br /> removing CO2 and enhancing oxygen transfer while limiting <br /> hydrocarbon removal to less than 0 1 pound per week Mr Mark <br /> Schonhoff of San Joaquin Valley Unified Air Pollution Control <br /> District, evaluating this source test as it pertains to air <br /> quality conditions in the Stockton area and has allowed Wickland <br /> to perform the weekly two hour venting of this well . <br /> The venting of MW8 commenced on Janaury 25, 1995 and lasted a <br /> duration of two hours The average flow rate calculated during <br /> this time was 49 cfm with a vapor stream composed of 0 . 13 mg/L as <br /> gasoline, 0 . 001 mg/L benzene and 311 carbon dioxide The weekly <br /> two hour venting of MW8 again occurred on February 1 and 8, 1995 <br /> Flow rate calculations showed similar rates of 53 and 52 cfm <br /> respectively. The vapor stream on February 1 contained 0 . 14 mg/L <br /> gasoline range hydrocarbons, 0 001 mg/L benzene and 3 . 3o CO2 <br /> The sample bag (tedlar) broke during the February 8th test <br /> therefore, no analysis of the vapor stream was conducted <br /> The above results show that the weekly two hour venting of MW8, <br /> is removing excess carbon dioxide and allowing oxygen transfer to <br /> occur A calculated 0 05 pounds of gasoline range hydrocarbons <br /> in being removed from MW8 weekly, see Table 4 and Appendix - <br /> Field Notes <br /> MW8 VENTING PROCEDURES <br /> We are using LTT vacuum trucks to pull an estimated 11 feet of <br /> water vacuum on MW8, for 2 hours weekly and exhaust directly to <br /> atmosphere This vacuum generates a flow rate of approximately <br /> 52 cfm. <br /> COLLECTING SAMPLES <br /> The sample is obtained from a sample port located, prior to the <br /> vacuum pump from a sample port on the flow meter orifice Sterile <br /> Poly tubing was used to attach a one liter tedlar bag, fitted <br /> PAGE 2 <br />