ARCHIVED REPORTS_XR0005707 CASE 2

Home Browse Search

URS Mr Mike Infurna Page 4 San Joaquin County Environmental Health Department ARCO 6020 September 29, 2003 On August 1,2003,top of casing elevations and lateral positions for the newly installed wells were surveyed to mean sea level by Morrow Surveying of West Sacramento, California Survey data are included as Attachment F Soil and Wastewater Disposal Soil cuttings and wastewater generated during the drilling activities were placed in labeled 55-gallon Department of Transportation(DOT)-approved steel drums and stored on site,pending disposal A composite soil sample was collected from the soil cuttings and submitted to the Sequoia Analytical Laboratory in Petaluma California, for analysis of TPHg, BTEX, and total lead under an accelerated 48-hour turnaround time The soil was hauled by Dillard Environmental Services to Forward Landfill in Manteca, California, ' where it was disposed of as non-hazardous waste Stockpiled soil laboratory analytical reports are included as Attachment G Soil and water disposal documentation is included as Attachment H Subsurface Conditions Soils encountered during drilling indicate the presence of silty sand and poorly graded sand with minor silts from ground surface to approximately 56 feet A 4-foot clay layer was encountered between 56 and 60 feet bgs m MW-13D A deeper silty sand layer was encountered between 60 and 70 feet bgs at this location A geologic cross-section of the site is presented as Figure 3 Soil boring logs are included in Attachment C Groundwater was encountered in sandy silt at approximately 25 feet bgs in the borings and stabilized at approximately 23 feet bgs in the monitoring wells During the third quarter 2003 groundwater monitoring j event conducted on July 28, 2003, depth to groundwater at the site ranged from 21 30 to 23 70 feet bgs Groundwater flow was to the north at an average gradient of 0 003 feet per foot (ft/ft), consistent with previous monitoring events (Table 1) A groundwater elevation contour map for third quarterly data is presented on Figure 4 Soil Analytical Data TPHg, BTEX, and fuel oxygenates were not detected at or above reporting limits in any of the eleven soil samples collected at from the three soil borings,with the exception of MtBE reported at 0 016 milligrams per kilogram (mg/kg) in the sample collected at 25 feet bgs from MW-13D MtBE was not reported in the samples collected at 20 feet and 45 feet in this boring Soil analytical data are presented in Tables 2 and 3 Laboratory analytical reports and chain-of-custody documentation are included in Attachment G K%WprocessU5 SP ARC010602012003 Assessment16020 Assessment&SCM 2003 doc