ARCHIVED REPORTS_XR0004984 - Laserfiche WebLink

Home Browse Search

v o M . A S S O C I A T E S I N C On June 16 through 19, 2003 ATC supervised four soil borings advanced utilizing cone penetrating testing (CPT) methods to approximately 160 feet bgs Soil and groundwater samples were collected from the four cone penetrometer soil borings and submitted for analysis On July 21, 2003, ATC conducted a 5-hour groundwater pumptest by extracting groundwater at a generally constant rate from the domestic well on site The extracted groundwater was sampled near the beginning and end of the test, and stored temporarily onsite in a 5,000-gallon polyethylene tank The details and results of the CPT borings and groundwater extraction test are described in ATC's Summary Report of Additional Subsurface Investigation, Pacific Coast Recreation, 3755 Munford Avenue, Stockton, California, to be submitted under separate cover SAMPLING ACTIVITIES On March 25 and 26 2004 A C personnel collected groundwater samples from monitoring 1 wells MW 1 through MW 10 a91he locations of the wells are shown on Figure 2 Prior to ) 1 collection of groundwater samples, the depth to water, pH, electrical conductivity, and temperature were measured in groundwater purged from the monitoring wells and recorded A minimum of three well casing volumes were purged from each monitoring well prior to sampling The wells were allowed to recover and samples were collected from each well using disposable polyethylene bailers After the groundwater samples were collected, dissolved oxygen was measured in each well The groundwater samples collected from each well were submitted to State-certified Argon Laboratories Inc (ELAP Cert No 2359) in Ceres, California for chemical analysis of TPHg utilizing EPA method 801513, benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA method 802113, and methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE) di-isopropyl ether (DIPE), tertiary amyl ether (TAME), tertiary butyl ether (TBA), 1,2- dichloroethane (1,2-DCA), 1,2-dibromoethane (EDB), ethanol, and methanol utilizing EPA method 8260B Groundwater well purge and sample logs are contained in Attachment I ANALYTICAL RESULTS Groundwater samples collected from wells MWI, MW2, MW3, MW6, MW8, and the domestic well DW contained the highest concentrations of TPHg and BTEX Groundwater samples collected from wells MW4, MW7, and MW10 also contained detectable concentrations of TPHg and/or BTEX constituents Detectable concentrations of TPHg ranged from 160,000 parts per billion (ppb) in MW2 to 130 ppb in well MW10 Detectable concentrations of benzene ranged from 21,000 ppb in MW2 to 15 ppb in well MW4 The groundwater samples collected from wells MW5 and MW9 contained no detectable concentrations of TPHg or BTEX Groundwater samples collected from wells MW1 through MW10 contained no detectable concentrations of oxygenate fuel additives although many of the reporting limits were elevated due to dilution • factors Analytical results of groundwater samples are summarized in Table 2 Laboratory data sheets and cham-of-custody documentation are contained in Attachment 2 f S IEnviromenta11163931REPORTs11gr-2004 doc 3