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GROUND ZERO ANALYSIS, INC. <br /> 1714 Main Street <br /> Escalon,California 95320 <br /> Telephone:(209)838-9888 <br /> Facsimile:(209)838-9883 RECEIVED <br /> ` July 14, 2011 <br /> JUL 19 2011 <br /> ENVIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> Mr. Nuel Henderson <br /> San Joaquin County Environmental Health Department <br /> 600 East Main Street <br /> �. Stockton, CA 95202 <br /> Subject: Remedial Progress Report—Second Quarter 2011 <br /> 1. 102 South Wilson Way, Stockton, Cali ornia(Figure 1) <br /> Dear Mr. Henderson: <br /> Ground Zero Analysis, Inc. (Ground Zero) has prepared this remedial progress report to <br /> summarize hydrogen peroxide injection activities conducted at the subject site during the second <br /> ` quarter of 2011. As proposed in the Workplan for Peroxide Injection Pilot Test, dated February <br /> 19, 2010, which was approved by the San Joaquin County Environmental Health Department <br /> ` (EHD) in correspondence dated May 11, 2010, site activities included monitoring groundwater <br /> elevations in all site wells, injecting hydrogen peroxide into select site wells and sampling select <br /> site wells. <br /> SITE ACTIVITIES <br /> Groundwater Monitoring <br /> A Ground Zero technician measured the depth to groundwater in all site wells May 16, 2011. <br /> The depth to groundwater was measured in monitoring wells MW 1 through W 17C and <br /> vapor wells V W 1 through V W6 and was then subtracted from each respective wellhead elevation <br /> to determine the groundwater elevation. Water levels at the site increased an average of 1.53 feet <br /> since last measured during the first quarter groundwater monitoring and sampling event in <br /> February 2011. The potentiometric surface was above the top of the screened intervals in <br /> IL monitoring wells MWl through MW13B, MW15B, MW15C, MW1613, MW17C and vapor <br /> wells VWI, VW3 and VW4. <br /> During this event, an upward vertical gradient component was present across much of the site. <br /> Wells screened deeper than 60 feet generally had higher potentiometric surface elevations than <br /> ` shallower wells in close proximity. An interpretive potentiometric surface map generated using <br /> the May 16, 2011, groundwater elevation data for the shallow groundwater monitoring wells is <br /> shown on Figure 2. A potentiometric surface map generated using groundwater elevation data <br /> ` from the deeper groundwater monitoring wells is shown on Figure 3. In both cases groundwater <br /> G:\GROONE)MROEK\REPORTSPermude Not Test\Repurts@QTR2011 Remedial Progress Repon.doc <br />