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Stantec
<br /> L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2010 SITE STATUS,
<br /> REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT
<br /> Introduction
<br /> January 31, 2011
<br /> Beginning on September 1, 2006 SPH is periodically extracted from a select group of L&M OU
<br /> monitoring wells that have had consistent SPH thickness over recent quarters. Extraction is
<br /> performed on groundwater wells MW-4, MW-10, MW-17, MW-19, MW-40, MW-43, MW-47,
<br /> MW-48, MW-49, and MW-52. SPH levels were monitored for four weeks following the initial
<br /> extraction event.
<br /> In September 2006, SECOR, along with Entact Environmental Services, commenced pipeline
<br /> abandonment and removal activities at 525 West Weber Avenue in the Waterfront Towers
<br /> Parking facility in accordance with Stantec's Pipeline Removal, Abandonment, Soil Excavation,
<br /> On-Site Horizontal SVE Well Installation, and Horizontal SVE Well Installation Beneath Delta
<br /> View Apartments Report and Work Plan for Pipeline Removal, Abandonment, and Soil
<br /> Excavation in Waterfront Towers Parking Lot dated February 10, 2005. A report entitled
<br /> Pipeline Removal, Abandonment, Soil Excavation, and Parking Lot Reconstruction summarizing
<br /> remedial activities and parking lot restoration at the Waterfront Towers Parking facility was
<br /> submitted on June 25, 2008.
<br /> On May 31, 2007, optimization of the DPE/SVE system, in accordance with SECOR's Work
<br /> Plan for Additional DPE Feasibility Testing and Expanded Remedial System Installation, dated
<br /> January 4, 2006, was completed and permitted to operate by the City of Stockton. A soil vapor
<br /> extraction system start-up and dual phase augmentation report was submitted on June 25,
<br /> 2008.
<br /> On June 21, 2007, well MW-6 on the MOU was destroyed and abandoned on behalf of the
<br /> SRDA and under the supervision of Golden State Environmental due to planned excavation and
<br /> construction activities.
<br /> From July 28 through September 26, 2008, additional assessment activities were conducted at
<br /> the Site. Five B-zone groundwater monitoring wells (MW-56 through MW-60), seven C-zone
<br /> groundwater monitoring wells (MW-61 through MW-67), and seven D-zone groundwater
<br /> monitoring wells (MW-68 through MW-74) were installed. Results were summarized in Stantec's
<br /> Additional Deep Groundwater Zone Assessment Report dated January 26, 2009.
<br /> In November 2008, Treadwell and Rollo (T&R) on behalf of the SRDA abandoned monitoring
<br /> wells MW-8, MW-10, MW-11, MW-39, MW-40, MW-41, and MW-53 due to excavation activities
<br /> on the UOU. These wells have yet to be reinstalled at the site.
<br /> In January 2009, T&R, on behalf of the SRDA, concluded their excavation activities on the
<br /> Unocal Operable Unit adjacent to the L&M OU. Treadwell and Rollo submitted their report of
<br /> findings entitled Removal Action Completion Report Unocal Operable Unit on Area 2A to the
<br /> RWQCB-CVR on August 5, 2009. A groundwater collection trench, extending north-south, was
<br /> left in the substrata approximately 15 feet bgs and along the eastern boundary of the excavation
<br /> which paralleled the major pipeline removed during the investigation.
<br /> I:\Tidewater\TW Stockton(Parcel 2A-0415)\Reports\QMR\2010\4010-Annual\4Q10 and Annual OSSRQRSRQMR Stockton_FINAL.doc 1.8
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