ARCHIVED REPORTS_SEPARATE PHASE HYDROCARBON INVESTIGATION UNOCAL EXTRACTION WELL PILOT STUDY 2011

Home Browse Search

Stantec Report of Findings for the Waterfront Towers Separate Phase Hydrocarbon Investigation and Unocal Extraction Well Pilot Study Waterfront Towers Parking Lot March 4, 2011 2004. The DPE system was temporarily deactivated on August 3, 2004, during the removal and abandonment of former pipelines found near the remediation system compound. To accommodate the excavation of the abandoned former pipelines and surrounding petroleum hydrocarbon-impacted soil, the remediation system conveyance lines and nearby sewer and water lines were also dismantled. Concurrently during the installation of the DPE system, SECOR submitted their Work Plan For Pipeline Abandonment, Removal, and Soil Vapor Extraction Well Installation, dated April 15, 2004. This report outlined a plan for abandoning or removing the steel pipelines that were discovered during the December 2003 underground utility search on the Parcel 2A property, and locating pipelines that were anticipated beneath West Weber Avenue and the Waterfront Towers parking lot and beneath former Edison Avenue near the eastern entrance to the Delta View Apartments. The work plan also proposed the installation of horizontal soil vapor extraction (SVE) wells to extract petroleum hydrocarbons from soil beneath five apartment buildings to the south, west, and northwest of the DPE remedial well field, and connection of those wells to the DPE system. The CRWQCB-CVR approved the April 15, 2004 work plan and the June 14, 2004 letter addressing CRWQCB-CVR comments to the work plan (Response to CRWQCB-CVR Letter Dated May 14, 2004) in electronic correspondence dated June 21, 2004. SECOR completed pipeline abandonment/removal activities during the fourth quarter 2004 (4Q04), and the installation and connection of horizontal SVE wells to the DPE system during the 1Q05. Pipelines discovered during the December 2003 investigation, as well as additional pipelines discovered during pipeline abandonment/removal activities, were removed from the undeveloped portion of the L&M OU, soil was excavated to approximately ten feet bgs, a 500-gallon steel UST was removed, an old unknown well was properly abandoned, and pipelines trending off the undeveloped portion of the L&M OU were rinsed and filled with cement. Approximately 300 gallons of product/water mixture were removed from three pipelines and approximately 350 gallons of product was pumped out of the UST. Horizontal SVE wells were installed beneath the bottom of the excavation and the bottom was lined with a high density polyethylene liner. Additionally, six horizontal SVE wells were installed beneath five apartment buildings in the Delta View Apartment complex. Final results and a work plan for additional pipeline removal in the Waterfront Towers parking lot are presented in SECOR's Pipeline Removal, Abandonment, Soil Excavation, On-Site Horizontal SVE Well Installation, and Horizontal SVE Well Installation Beneath Delta View Apartments Report and Work Plan for Pipeline Removal, Abandonment, and Soil Excavation in Waterfront Towers Parking Lot, dated February 10, 2005. Additional assessment activities were conducted at the Site in May 2004 to investigate the vertical extent of petroleum hydrocarbons in the vicinity of the Site. SECOR advanced one deep soil boring (SB-7) to a depth of approximately 140 feet bgs in the vicinity of well MW-17, installed shallow off-site well MW-45, and installed deep off-site wells MW-40 through MW-44 and MW-46. Three groundwater samples were collected at 117, 128, and 139 feet bgs using a 2.6