SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

GROUND ZERO ANALYSIS, INC. 1714 Main Street Escalon, California 95320-1927 Telephone: (209)838-9888 Facsimile: (209) 838-9883RE" VE® ler November 11,2004 NOV 1 !i 1004 EPV1.b;)igbRW flEAUN ' MICEs Ms.Lori Duncan San Joaquin County Public Health Services Environmental Health Division 304 East Weber Avenue,Third Floor Stockton,CA 95202 Subject: Gabbard Property, 640 N.El Dorado Street, Stockton,California Dear Ms.Duncan: Ground Zero Analysis, Inc. (Ground Zero) is writing on behalf of Gene Gabbard, Inc. in response to your letter dated October 26, 2004 regarding the subject site. Your letter included comments on the March 16, 2004 investigation summary report and the August 18, 2004 groundwater monitoring report, summarizes a project meeting held at the San Joaquin County Environmental Health Department (SJC/EHD) office, and requests a workplan to continue the investigation of the vertical and lateral extent of subsurface contamination at the site. Ground Zero has the following responses: Comments on March 16,2004 Groundwater Monitoring Well Installation Report As indicated in your letter, Ground Zero's workplan for investigation included drilling three pilot borings to a depth of approximately 50 feet below ground surface (bgs) to determine lithology beneath the site and to sample groundwater in each boring from both the first water-bearing zone and from the bottom of each boring. Your letter indicates that the workplan was not carried out,because water samples were not collected at the bottom of borings S139 and SB 11. Ground Zero would like to clarify that the workplan was indeed carried out. Each boring was advanced to 50 feet bgs, and a groundwater sampling device was deployed at the bottom of each boring. Ground Zero made every effort to collect the groundwater samples pursuant to the workplan, but soil formation at the 50-foot bgs level did not yield groundwater. Subsurface conditions dictated the outcome of the investigation,not disregard for the workplan. Comments on September 29,2004 Project Meeting As indicated in your letter,Ground Zero presented an analysis of the distribution of dissolved PCE in shallow groundwater beneath the site, which suggested that an off-site source of PCE exists. Ground Zero discussed the likelihood that the Unifirst Corporation industrial laundry facility located approximately 1 block north of the subject site is the most likely source of the PCE contamination, given the location and flow direction of the city sewer beneath El Dorado Street. The Unifirst site was the location of a dry cleaner from the 1920s through 2002. It is widely recognized that contamination originating from dry cleaning facilities can enter the environment through leaking sewers. G:\GROUNDZE\GABBARD\wmspon\ehd—offsite.DOC