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Stantec
<br /> Report of Findings for the Waterfront Towers Separate Phase Hydrocarbon Investigation
<br /> and Unocal Extraction Well Pilot Study
<br /> • Waterfront Towers Parking Lot
<br /> March 4, 2011
<br /> activities. Results from the pilot testing were used to design and implement remedial system
<br /> upgrades to better optimize contaminant mass removal from soil and groundwater beneath the
<br /> L&M OU. Remedial system upgrade installation activities were completed during 2Q07.
<br /> Beginning on September 1, 2006, SPH was periodically extracted from a select group of L&M
<br /> OU monitoring wells which have had consistent measurable SPH thickness over recent
<br /> quarters. Extraction is performed on groundwater wells MW-4, MW-10, MW-17, MW-19, MW-
<br /> 40, MW-43, MW-47, MW-48, MW-49, and MW-52. SPH levels were monitored for four weeks
<br /> following the initial 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 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/Dual-Phase Augmentation Report was submitted on June 25, 2008.
<br /> On June 21, 2007, MW-6 on the MOU was destroyed and abandoned under the supervision of
<br /> Golden State Environmental due to excavation and construction activities.
<br /> From July 28 through September 26, 2008, five B-zone groundwater monitoring wells (MW-56
<br /> through MW-60), seven C-zone groundwater monitoring wells (MW-61 through MW-67), and
<br /> seven D-zone groundwater monitoring wells (MW-68 through MW-74) were installed. Results
<br /> were summarized in Stantec's Additional Deep Groundwater Zone Assessment Report, dated
<br /> January 26, 2009.
<br /> In November 2008, T&R, on behalf of the SRDA, abandoned wells MW-8, MW-10, MW-11,
<br /> MW-39, MW-40, MW-41, and MW-53 due to excavation activities on the UOU. These wells
<br /> 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 UOU
<br /> adjacent to the L&M OU. Treadwell and Rollo submitted their report of findings entitled
<br /> Removal Action Completion Report Unocal Operable Unit on Area 2A to the CRWQCB-CVR on
<br /> August 5, 2009. A groundwater collection trench, extending north-south, was left along in the
<br /> 2.8
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