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<br /> ENSR International
<br /> 10411 Old Placerville Road
<br /> FEB 1 9 2004 Suite 210
<br /> February 17, 2004 Sacramento,CA 95827 2508
<br /> ENVIRlIiI Mti�i t,LHLTH (916)362 7100
<br /> PERMIT/SERVICES FAX (916)362-8100
<br /> ' www ensr cam
<br /> Mr James L Barton
<br /> California Regional Water Quality Control Board
<br /> ' Central Valley Region
<br /> 11020 Sun Center Drive, Suite 200
<br /> ' Rancho Cordova, CA 95670-6114
<br /> RE Updated Site Conceptual Model, Monitoring and Remediation Status Report
<br /> ' Fourth Quarter 2004, Former Unocal Facility # 5098
<br /> 5400 and 5606 Pacific Avenue, Stockton, CA
<br /> Dear Mr Barton
<br /> ENSR Corporation (ENSR) has been authorized by Union Oil Company of California (Unocal) to
<br /> ' prepare an updated Site Conceptual Model (SCM) and Fourth Quarter 2003 Monitoring and
<br /> Remediation Report for the subject site The former site facilities were located at the former
<br /> Montgomery Ward, LLC (Wards) site located at 5400 Pacific Avenue and the former Union Oil it
<br /> Company of California (Unocal) site located at 5606 Pacific Avenue, Stockton, California
<br /> (Figure 1) Groundwater monitoring was conducted pursuant to requirements of Cleanup and
<br /> Abatement Order No 5-00-707, issued to Wards, Unocal, Surry California Limited Partnership,
<br /> and Stone Brothers and Associated General Partnership on September 8, 2000, by the
<br /> California Regional Water Quality Control Board, Central Valley Region (RWQCB)
<br /> (Section 1 1 5) The locations of former and current site features are illustrated on Figure 2
<br /> The work was performed in accordance with the field methods and procedures included in
<br /> ' Attachment A
<br /> Groundwater Level Measurements
<br /> ' Depth to groundwater measurements were recorded in wells MW-1 through MW-10, MW-10A,
<br /> MW-11 through MW-14, MW-14A, MW-15, MW-17, MW-18, MW-18D, MW-19S,
<br /> ' MW-19D, MW-21 S, MW-21D, MW-22S, MW-22D, MW-23S, MW-23D, MW-24S, MW-24D,
<br /> MW-25S, MW-25D, MW-27, and AS-26 on December 16, 2003 and MW-16 on
<br /> December 29, 2003 Tabular results of recent depth to water (DTW) measurements are
<br /> summarized in Table 1.
<br /> Groundwater measurements recorded on December 16, 2003 from wells MW-10A, MW-14A,
<br /> MW-18, MW-19S, MW-21S, MW-22S, and MW-25S screened in Unit A were used to construct
<br /> ' the groundwater elevation contour map included as Figure 3 On December 16, 2003, the
<br /> groundwater flow direction for Unit A was generally southeast, with an average hydraulic gradient
<br /> of approximately 0 005
<br /> Groundwater measurements recorded on December 16, 2003 from wells MW-1 through MW-7,
<br /> MW-9 through MW-15, MW-17, MW-18D, MWA 9D, MW-21 D, MW-22D, MW-25D, MW-27, AS-26
<br /> screened in Unit B were used to construct the groundwater elevation contour map included as
<br /> J\Projects1069401293-50981Ftnall4th Qtr'03-QMR RSR doc
<br /> ' 35 Years of Excellence in Environmental Services
<br />
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