ARCHIVED REPORTS XR0007668 - Laserfiche WebLink

Home Browse Search

Firestone Service Center 400 North El Dorado, Stockton, California February 2, 1994 Sod Remediation Plan — 2072.01 Page 1 of 6 1 .0 SITE DESCRIPTION AND HISTORY 4 Ryan-Murphy, Inc has prepared and submitted a Site Assessment Report, dated February 2, 1994, for the subject site located at 400 North EI Dorado Street, Stockton, California A Site Vicinity Diagram is shown on Figure 1 . The assessment report provides a summary of events occurring prior to October 13, 1993, and the complete results of assessment activities performed on October 13 and 14, 1993 Data pertinent to the discussion of remediation alternatives is summarized herein Prior to initiation of site assessment activities, tanks 4 and 5 were removed and soil borings were installed Subsequently, overexcavation was performed and samples of the pit walls and floor were collected and analyzed The east pit wall was not overexcavated due to the proximity of the budding foundation Samples collected from the overexcavation pit walls and floor, at approximately 11- and 13-feet below grade respectively, exhibited total petroleum hydrocarbon (TPH-gas) concentrations of 1000- to 1800-mg/kg The east wall sample, collected at the time of tank removal, had a TPH- gas concentration of 2200-mg/kg These concentrations exceed the established action level for TPH-Gas of 100-mg/kg Based on the results from the overexcavation sample analyses, the October 1993 assessment was performed to delineate the extent of petroleum contaminated soil remaining in place The assessment report presents data from soil borings and well installation completed October 13 and 14, 1993 Based on the reported laboratory analytical results, the lateral and vertical extent of petroleum hydrocarbon contamination has been identified However, the report describes field observations and photoionization detector (PID) readings which indicate the presence of volatile hydrocarbons in the soil at 13- to 28-feet below grade A 4-inch diameter well was completed for potential use as a vapor extraction well The well was screened from 18- to 28-feet The subsurface soil at the site consists of approximately 15-feet (from the surface) of silt with varying amounts of clay and fine sand, a layer of clean, fine to medium grained sand from 15- to 20-feet, followed by 15-feet of sandy to clayey silt The overexcavated pit i area was backfilled with pea gravel from full depth (13 ft ) to the surface Evidence of ■ groundwater was not encountered to a depth of 35-feet in the October 1993 soil borings and 41 .5-feet in borings completed September 1991 It is estimated that groundwater is at a depth of 50-feet or greater in this area Groundwater depth was estimated based on information provided by the California Department of Water Resources, Central Districts 1990 publication H►stoncal Groundwater Levels In San Joaquin County and the San Joaquin County, Flood Control and Water Conservation Groundwater Report, Spring 1993 Refer to the subject report for further information concerning site activities, site lithology, monitoring, and analytical results RYAMMIJRMY, INCORPORATM FAvkoamentnl Construction Management Los Angela