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California R�jonal Water Quality �,)ntrol Board <br /> Central Valley Region <br /> Winston H.Hickox Steven J.Butler,Acting Chair GrayDavis <br /> Secretary for Governor <br /> irnn <br /> Envmenra! Sacramento Main Office <br /> Pron iun Internet Address: http://www.swrcb.ca.gov/—rwgcb5 <br /> 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 <br /> 1 <br /> TO: Gordon L. Boggs FROM: Mark R. List <br /> UST Prograo Manager Engineering Geologist <br /> a <br /> DATE: 25 January 1999 SIGNATURE: <br /> SUBJECT: FILER VIEW FOR CLOSURE CONCURRENCE DETERMINATION, CITY OF <br /> STOCK ON FIRE STATION#7, 1767 WEST HAMMER LANE, STOCKTON, <br /> SANJ AQUINCOUNTY <br /> At the request of the San Joaquin County Environmental Health Division (SJCEHD), a file review was <br /> completed to determine if Regional Board staff concur with the SJCEHD determination of no further <br /> action required at this site. This information was obtained during my review of the Regional Board <br /> casefile, and during discussions with Ms. Margaret Lagorio of San Joaquin County. <br /> Background: <br /> On 9 March 1994, one 500-gallon diesel underground storage tank (UST) was removed from the site. A <br /> soil sample collected beneath the UST revealed elevated concentrations of total petroleum hydrocarbons <br /> as diesel (TPHd). In December 1996 four soil probe borings were advanced for soil and groundwater <br /> sampling. The analytical results of soil sampling reported TPHdiesel contamination from 13 to 16 feet <br /> below ground surface (bgs) beneath and near the former UST location. Low concentrations of <br /> ethylbenzene and total xylenes were also identified in the soil samples. The single grab groundwater <br /> sample contained 72 gg/L (ppb) TPHd, 0.6 gglToluene and 0.7 gg/L total xylenes. Benzene, <br /> ethylbenzene and MTBE were not detected above the laboratory reporting limits in the water sample. <br /> Based on calculations provided by Advanced Geo-Environmental, approximately 20 gallons of TPHd <br /> remain in soil to approximately 16 feet bgs near the former UST location. Additionally, low <br /> concentrations of TPHd are present in groundwater below the site. Groundwater surface elevation in the <br /> area has fluctuated between 25 and 40 feet bgs and no drinking water wells have been impacted. <br /> Summary: <br /> The soil below the Fire Station#7 site has been impacted with TPHd contamination. Additionally, low <br /> concentration of TPHd, toluene and total xylenes were identified in groundwater collected below the <br /> former UST location. TPHd contamination in soil is limited in vertical and lateral extent, and <br /> groundwater contamination is of very low concentration. Based on the information provided in the <br /> casefile and by San Joaquin County, concurrence with the no further action required decision appears <br /> warranted. <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />