WORK PLANS - Laserfiche WebLink

Home Browse Search

January 10, 1996 - Page 2 PREVIOUS INVESTIGATIONS In February 1995, The MARK Group, Inc. (MARK) conducted a Phase I Environmental Site Assessment(ESA). The.ESA included a field reconnaissance of the site and adjacent properties, literature reviews regarding historical land-use and hydrogeology, interviews, and review of governmental environmental databases. Based on the results of the ESA, further environmental investigation was recommended (MARK, February 1995). In April 1995, MARK conducted a preliminary subsurface investigation which included the drilling of six exploratory borings. The six borings included one adjacent to the former waste oil tank, one at the location of the former hydraulic hoist, one at the location of the former pump island, one adjacent to the location of the former product lines, and two at the location of the former gasoline USTs. Total purgeable petroleum hydrocarbons calculated as gasoline (TPPH-g), and benzene, toluene, ethylbenzene, and xylenes (BTEX compounds) were detected at 3 feet below ground surface (bgs) within the former UST excavation backfill. TPPH-g and benzene were detected at concentrations of 170 parts per million (ppm) and 0.051 ppm, respectively. No TPPH-g or BTEX compounds were detected in any of the other samples collected (MARK, April 1995). Subsurface materials encountered during drilling included near-surface clayey fill and clayey fill with concrete debris within the former UST excavation backfill, and native soil consisting of clay. Groundwater was not encountered and based on regional information groundwater flow is estimated to be to the southwest at a depth in excess of 50 feet (MARK, April 1995). i PROPOSED SCOPE OF WORK The scope of work for this investigation has been proposed to confirm the presence and -evaluate the extent of gasoline hydrocarbons (if present) in soil and groundwater. { Prior to performing field work at the site,PACIFIC will prepare a Site-Specific Health and Safety Plan required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120). The Site-Specific Health and Safety Plan will be reviewed by the project manager,field staff and contractors prior to beginning field operations at the site. Applicable permits for well installation will be obtained from the San Joaquin County Department of Public Health Services,Environmental Health Division prior to drilling. The specific scope of work is discussed below: • Geophysical Survey. A geophysical survey, which will include the use of ground penetrating radar (GPR) and magnetometer 9200391A/WPLAN