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05/03/1999 09 51 7078382323 GALLARDO AND ASSOC PAGE 16 Page 12 Limited Soft and G rouadwater Report-05/24/99 western pat&S r Site to ed No 024,98 14,0 CONCLUSIONS 1Based on the accumulated site history data,the current luted sowgroundwata investigation,and results Gallardo&Associates concludes the followmg- results collected rom the�3ve exploratory soil borings (B-.1 through 8--5) • Soil sampling f indicate deal the soil located beneath the properly at soil boring locadorus B-1, B-2, and B-4 has been i"Wacted by moderate concentrations of TPH-g, TP1 d, and T'Pli lr. a flue Verdcal extent of the impacted soil appears to end at approximately 34 h feet bgs at ' ging¢2, and appmadmately 29 51 feet bgs at borwg B-4. However, vertical definition was not defined at boring,6141• The impacted soil extended below the 40-foot maximum depth of the investigation as defined in the approved workplan. • The hortzvntal cadent of the a»ipacted soil appears to be restricted to the area surrowuding the 20,000-gallon iIST' No impacted soil was detected beneath soil boring B located within the former diesel and gasoline UST's candy. • The hwhest concentrations of impacted soil appear to be centered beneath borings B-1 (TPH-d at 30,000 ppm and T,Pff k at 18,000 ppm) and B-2 (TpH-d at ,13,000 ppm and T1PH--kat 11,000 ppm)at an approximate depth of 29 %feet bgs. lin addition' analytical results colleccdeded from soil boring 8-4 indaate that concentrations Q,f'T PH d at 1,800 ppm and TPff k at 1,700 ppm exists at art WroxinWe depth of 14 '/2 feet bg& The depth to the true water table was not encountered during this investigation;however, a shallow perched water zone was detected at an approximate depth of 29 Y2 feet bgs • The shaliow groundwater (perched) detected at soil boring B-4 has been impacted by concentrations TPH 4 TPH k, TFH g,andBTS awever, this shallow groundwater body was only detected in soil boring B-4. The extent of impact to this POMIbly perched groundwater could not be deterrnuned during this limited investigation. l • The direction of groundwater,f Lor►'could not be detern ned during this invesdgation. ' 11.0 g,ECOMMENUATIONS Based on the data presented, Gullardo&Aswiates supports the following rerom=ndattOns • Since the surrounding groundwater has abeady beers impacted by saline water emanating from the adjacent Tactor Sausage site currently under investigation by the Centml Valley Regioned 1K'ater Qualdy Control Board(CVRWQCB), `md the fact that the irnparcted soil detected beneath the )GYestern Oil& spreading site property consists mainly of blebs of Sema-viscous asphalt that are probably not Likely to leach down unto the deeper ' groundwater zone suspected to be at a depth below 40 feet bgs, Gallardo &Associates u requests that San Joaquin County Environmental Health Division consider granting site Iclosures