ARCHIVED REPORTS_XR0007128 - Laserfiche WebLink

Home Browse Search

~ WASHINGTON TE PnO+ (206) 985 ?GCO OREGON CALIFORNIA 12 TO NEVADIDAHOA 4 ' 23 K TIME OIL C O . , 7 e T' 2737 WEST COMMODORE WAY SEATTLE,WA 98199-1233 PRODUCTS TPO BOX 24447 SEATTLE,WA 98124-0447 TIME TEST` / E �/ April 26, 2000 Mr Harlin Knoll San Joaquin County Public Health Services Environmental Health Division P O Box 2009 Stockton, California 95201 RE Submittal of First Quarter 2000 Groundwater Monitoring Report for Jackpot Food Mart, 14000 E Highway 88, 1_ockeford, California (Property No 04-049) Dear Mr Knoll, At the request of the San Joaquin County Public Health Services Environmental Health Division (PHS/EHD), an additional environmental investigation was implemented at the subject site in December 1994 to evaluate the extent of hydrocarbon-impacted soils and to determine whether or not groundwater had been Impacted A total of four groundwater monitoring wells were installed during this investigation In July 1996, six additional groundwater monitoring wells were installed on and off of the subject site to assist In defining the extent of groundwater impacts Based on the results of the investigations, Time Oil Implemented groundwater monitoring Please find enclosed Science & Engineering Analysis Corporation's(SECOR's) "Quarterly Monitoring Report, January — March 2000' dated April 24, 2000 This document presents analytical results and field observations collected during First Quarter 2000 groundwater sampling First Quarter 2000 Groundwater Sampling Results On February 17, 2000, samples were collected from each of the groundwater monitoring wells (MW-1 through MW-10) at the subject site by a representative of SEC04R Prior to purging, the depth to water in each well was measured to evaluate elevation, flow direction, and gradient As noted in the attached report, groundwater w:th a southwesterly flow direction and a gradient of 0 03 ft/ft was encountered in the wells at depths of 67 07 feet to 80 00 feet below ground surface Free product was encountered in MW-1 (4 79 feet) The locations of the wells are identified on Figure 2 of the attached report Since the November 1999 sampling event, groundwater elevation increased in MW-3 by 0 35 feet while it decreased in the remainder of the wells by 0 10 feet to 4 84 feet These changes resulted in an overall average decrease in groundwater elevation of 1 05 feet across the site Changes In groundwater elevation are most Iikeiy a result of seasonal vanation Groundwater gradient and flow direction remained consistent with previously collected data Table 1 in the attached report summarizes groundwater elevation data collected to date Analyses identified elevated concentrations of hydrocarbons and/or MTBE in the samples collected from MW-3 (1,150 ppb TPH-g, 144 ppb benzene, B5 6 ppb toluene 51 ppb ethylbenzene, 82 ppb xylenes and 1 4 ppb MTBE) MW-4 (760 ppb TPH-g, 91 8 ppb benzene 1 2 ppb toluene, 55 5 ppb ethylbenzene, 6 1 ppb xylenes, and 10 1 ppb MTSE), and MW-9 (124 ppb TPH-g, 5 2 ppb benzene, 0 7 ppb ethylbenzene, and 4 6 ppb xylenes) lower concentrations of hydrocarbons were found In the samples collected from MW-5 (88 ppb TPH-g and 0 9 ppb MTBE) MW-6 (62 ppb TPH-g and 1 2 ppb xylenes), MW-7 (0 7 ppb toluene and 1 0 ppb xylenes), MW-8 (64 ppb TPH-g and 1 0 ppb xylenes) and MW-10 (82 ppb TPH-g, 0 9 ppb toluene, and 2 9 ppb xylenes) Hydrocarbons were not detected In the sample collected from MW-2 No sample was