WORK PLANS - Laserfiche WebLink

Home Browse Search

_ ENVIRONMENTAL HEALTH DEPARTMENT f P U SAN JOAQUIN COUNTY y Donna K Hcran, R .&H.S . Unit Supervisors y r Durc to? 304 East Wcbcr Avemie, Third Floor Cul Bnigmmn, RE.x s Laurie A. Cotulla, R.C.H.S, Stockton , California 95202-2708 Mike Huggins, R . E Hs. , R.D .I . vrogram Manager Telephone : (209) 468-3420 Douglas w, Wilson, R E H.S . _I i) Foa Margaret Lagorio, R.E.H. S . Fax : (209) 464-0138 Robert McCletion , R.E. H.s . Website: www. sjgov.org/ehd/ .teff Carrue.sco, R.E.H.S. 1 'j DAVID GUARDINO AND PAT GUARDINO JUN 2 7 2006 _ GUARDINO AND CRAWFORD CONSTRUCTION 517 W FREMONT ST STOCKTON CA 95201 u ; RP.: GUARDINO AND CRA WF'ORD ' � %/j//� SI'TE CODE: 1112 517 W Fremont St. Stockton CA 95201 w _1 San Joaquin County Environmental Health Department (EHD) has reviewed I iowM Quarter Monitoring Repor22005 dated April 12, 2006 prepared by your consultant, Advanced GeoRnvironmental, Inc. (AGF.) . the groundwater contamination plume has remained centered around monitoring well N1W-1 located approximately 7 feet south of the tank excavation and near the piping trench. The recent analytical results of MW- 1 groundwater E I samples were 32,000 micrograms per liter (ug/1) total petroleum hydrocarbons as gasoline f (IPH-g) and 8,600 ug/I benzene. The only otherwell with contamination detected was MW-2 at 7.7 ug/1 benzene and "non detect" for '01-1 g. The remaining six monitoring wells, 1AW-3 to NIW- 8, were all "non-detect" fur all analytes including 'ITH-g, aromatic hydrocarbons, 5 oxygenates, and 1,2-dichlotoethane and 1 ,2-dibromoethane. The highest contaminant concentrations in N1W-I were recorded in November 2000 at 120,000 ug/I TPH-g and 18,000 ug/1 benzene. The concentrations rose again in September 2005 to E_ 8$00 ug/I TPH-g and 40,000 ug/1 benzene (the highest for benzene) . Historical groundwater low elevation was approximately 55 feet below surface grade (bsg,) in 1978 accotding to San Joaquin County Flood Control lines of Fqual Depth to Groundwater in JSpring 1978. Groundwater flow direction was toward the notthwest in the past, but has shifted toward the east and northeast the last few qunrteds. ( i { Results of historical quarterly samplings of the monitoring wells since July 1999 indicate the cote of the groundwater plume to be in the immediate area of MW-1 . One lateral edge of - the plume extends to approximately NAV-2 where the concentrations have declined significantly since 1999. Results of deep grab groundwater samples collected by cone- penetrometer testing boring CPTI at 33, 55, and 80 feet below surface grade (bsg) in October 2004 were "non -detect" for all analytes. The groundwater plume appears to be defined both laterally and vertically. The bottom of the tank excavation in June 1989 was approximately 13.5 feet bsg, and 4.5 feet bsg in the piping and dispenser area. Although neither odor not discoloration was noted in the three soil samples (2 tank pit and I piping samples);, the analytical results of soil sample #2 (south) were 68 kg/mg TPI 1-g, and from soil sample #3 (piping) the results were I i