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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 /> simultaneously from the test wells by applying a high vacuum to a drop tube that was lowered
<br /> below the water table within each test well. Results of DPE feasibility testing indicated the
<br /> following: (1) an effective radius of influence of at least 36 feet to the west of 2AMW-14; and (2)
<br /> the removal of an estimated 212.3 lbs (34.2 gallons) of TPHg from soil vapor, and approximately
<br /> 0.29 lbs (0.05 gallons) of TPHg, 17.56 lbs (2.46 gallons) of TPHd, and 8.29 lbs (1.13 gallons) of
<br /> TPHo from groundwater. Results are summarized in SECOR's report entitled Results of
<br /> Additional DPE Feasibility Testing, dated May 23, 2003.
<br /> Between March 10 and April 9, 2003, 12 shallow zone groundwater monitoring wells (MW-18
<br /> through MW-23, MW-25, MW-28, MW-30, MW-31, MW-33, and MW-34), eight deep zone
<br /> groundwater monitoring wells (MW-16, MW-17, MW-24, MW-26, MW-27, MW-29, MW-32, and
<br /> MW-35) were installed, and seven soil borings (SB-1 through SB-6 and MW-16A) were
<br /> advanced at the Site. Results are summarized in SECOR's Additional Assessment Report,
<br /> dated May 30, 2003.
<br /> Between October and December 2003, five additional DPE wells (DPE-8 through DPE-12) were
<br /> installed and a DPE remediation system was installed at the Site. The DPE system is
<br /> connected to wells DPE-1 through DPE-12. Additionally, a Non-aqueous Extraction Technique
<br /> (NETTM) SPH removal system was installed to include well 2AMW-14. System installation
<br /> activities are summarized in SECOR's DPE Well and System Installation Report, dated
<br /> December 5, 2003.
<br /> On December 17, 18, and 22, 2003, exploratory excavations were conducted at the Site to
<br /> locate underground utilities including former product pipelines. Steel pipelines were discovered
<br /> at the Site at 14 locations. Results are summarized in SECOR's Revised Underground Utility
<br /> Search Report, dated March 5, 2004.
<br /> In January 2004, SECOR completed construction of the DPE system. Electrical power and
<br /> natural gas services were established by Pacific Gas and Electric (PG&E) on March 4, 2004.
<br /> Under the conditions of the initial air permit for the DPE system issued by the San Joaquin
<br /> Valley Air Pollution Control District (SJVAPCD) in April 2003, which covered the first six months
<br /> of system operation utilizing propane as a fuel source, startup of the DPE system was
<br /> performed and initial groundwater and air influent and effluent samples were collected on March
<br /> 18, 2004. SECOR submitted a request to the SJVAPCD for modifying the existing air permit,
<br /> which included the operation of the DPE system using natural gas rather than propane, and
<br /> extension of the life of the permit to cover five years of operation. SJVAPCD required that the
<br /> revised permit be resubmitted for public review over a 30-day period, which ended on July 15,
<br /> 2004. Throughout the duration of the review period, the SJVAPCD did not authorize the
<br /> operation of the DPE system under the existing permit due to minor detections of polyaromatic
<br /> hydrocarbons (PAHs) in the effluent sample collected on March 22, 2004. Since no public
<br /> 0 comments were received by July 15, 2004, the SJVAPCD issued the revised air permit on July
<br /> 20, 2004. Initial start-up and shake-down of the DPE system was performed on August 2 and 3,
<br /> 2.5
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