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S E C O R 10
<br /> • property, and locating pipelines that were anticipated beneath West Weber Avenue and the
<br /> Waterfront Towers parking lot and beneath former Edison Avenue near the eastern entrance to
<br /> the Delta View Apartments. The work plan also proposed the installation of horizontal soil vapor
<br /> extraction (SVE) wells to extract petroleum hydrocarbons from soil beneath five apartment
<br /> buildings to the south, west and northwest of the DPE remedial well field, and connection of
<br /> those wells to the DPE system. The RWQCB approved the April 15, 2004 work plan and the
<br /> June 14, 2004 letter addressing RWQCB comments to the work plan (Response to
<br /> CRWQCB-CVR Letter Dated May 14, 2004) in electronic correspondence dated June 21, 2004.
<br /> SECOR completed pipeline abandonment/removal activities during the fourth quarter 2004, and
<br /> the installation and connection of horizontal SVE wells to the DPE system during the first
<br /> quarter 2005. Pipelines discovered during the December 2003 investigation, as well as
<br /> additional pipelines discovered during pipeline abandonment/removal activities, were removed
<br /> from the undeveloped portion of the L&M OU, soil was excavated to approximately 10 feet bgs,
<br /> a 500-gallon steel UST was removed, and old well was properly abandoned, and pipelines
<br /> trending off the undeveloped portion of the L&M OU were rinsed and filled with cement.
<br /> Approximately 300 gallons of product/water mixture were removed from three pipelines and
<br /> approximately 350 gallons of product was pumped out of the UST. Horizontal SVE wells were
<br /> installed beneath the bottom of the excavation and the bottom was lined with a high density
<br /> polyethylene (HDPE) liner. Additionally, six horizontal SVE wells were installed beneath five
<br /> apartment buildings in the Delta View Apartment complex. Analytical results of soil samples
<br /> collected at the bottom of the excavations indicated maximum concentrations of TPHd, TPHo,
<br /> TPHg, benzene, Methyl tertiary Butyl Ether (MtBE), and Tertiary Butyl Ether (TBA) of 12,000
<br /> milligrams per kilogram (mg/kg) (EX-3-13-J-10'), 2,200 mg/kg (EX-2-B-D-10' and EX-3-B-D-10'),
<br /> • 5,400 mg/kg (EX-2-B-B-10'), 0.60 mg/kg (EX-3-B-J-10'), 0.0056 mg/kg (EX-3-B-G-10'), and 0.87
<br /> mg/kg (PLG-3-C-10'), respectively. Soil samples collected from the sidewalls of the excavations
<br /> contained TPHd, TPHo, TPHg, benzene, and TBA at maximum concentrations of 25,000 mg/kg
<br /> (EX-2-W-A-5'), 1,700 mg/kg (EX-3-W-A-5' and EX-3-W-A-8'), 2,400 mg/kg (EX-4-NE-8'), 0.060
<br /> mg/kg (EX-3-W-A-5'), and 0.82 mg/kg (EX-1-W-B-5'), respectively. MtBE was not detected at
<br /> or above laboratory method reporting limits (MRLs) in the sidewall samples. Interim results of
<br /> the investigation are presented in SECOR's Interim Pipeline Removal and Abandonment and
<br /> Soil Excavation Report, dated December 22, 2004. Final results and a work plan for additional
<br /> pipeline removal in the Waterfront Towers parking lot are presented in SECOR's Pipeline
<br /> Removal, Abandonment, Soil Excavation, On-Site Horizontal SVE Well Installation, and
<br /> Horizontal SVE Well Installation Beneath Delta View Apartments Report and Work Plan for
<br /> Pipeline Removal, Abandonment, and Soil Excavation in Waterfront Towers Parking Lot dated
<br /> February 10, 2005.
<br /> Additional assessment activities were conducted at the Site in May 2004 to investigate the
<br /> vertical extent of petroleum hydrocarbons in the vicinity of the Site. SECOR advanced one
<br /> deep soil boring (SB-7) to a depth of approximately 140 feet bgs in the vicinity of well MW-17,
<br /> installed shallow off-site well MW-45, and installed deep off-site wells MW-40 through MW-44
<br /> and MW-46. Three groundwater samples were collected at 117, 128, and 139 feet bgs using a
<br /> HydropunchTM sampling device in soil boring SB-7. Laboratory analysis of groundwater from
<br /> S13-7 indicated maximum concentrations of TPHd, TPHo, TPHg, benzene, MtBE, and TBA of
<br /> 8,300 micrograms per liter (ug/L; 139 feet bgs), 3,200 ug/L (139 feet bgs), 1,800 ug/L (117 feet
<br /> bgs), 200 ug/L (117 feet bgs), 4.5 ug/L (117 feet bgs), and 100 ug/L (117 and 128 feet bgs),
<br /> respectively. Two deep zone wells, MW-40 and MW-43, contained measurable SPH. Results
<br /> are summarized in SECOR's report entitled Additional Assessment Report and Work Plan for
<br /> • Additional Deep Groundwater Zone Assessment dated July 29, 2004.
<br /> 1 Q08QSSRQRSRQMR.F1nal.doc 5 April 30,2008
<br /> 77TW.26397.42.1307
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