|
rc 1117 Lone Palm Avenue, Suite
<br /> V Modesto, CA 953511
<br /> www.atcassociates.com
<br /> 209-579-2221
<br /> A S S O C I A T E S I N C . Fax 209-579-2225
<br /> ironmental,Geotechnical and Materials Engineers
<br /> In October 2004, ATC supervised the installation of four groundwater monitoring wells (JLM12,
<br /> JLM13, JLM14, and JLM15). Petroleum hydrocarbons were detected in groundwater samples
<br /> collected from JLM12 and JLM13. The direction of groundwater flow was to the southeast on
<br /> November 23, 2004. Refer to ATC's Well Installation Report, dated December 23, 2004, for
<br /> additional information.
<br /> On February 17, 2005, ATC personnel collected a grab sample from the onsite supply (OSW) at the
<br /> request of the CRWQCB prior to the destruction of OSW. On March 2, 2005, the OSW was
<br /> destroyed by explosive means. Refer to ATC's Well Destruction Report, dated April 4, 2005, for
<br /> additional information.
<br /> On July 18, 2005, an ATC geologist supervised the advancement of CPTI, CPT2, and CPT3 to
<br /> depths of 137, 78, and 91 feet below ground surface (bgs), respectively. Groundwater samples were
<br /> collected at a depth of 130 feet from CPTI; 70 feet from CPT2; and 87 feet from CPT3. Petroleum
<br /> hydrocarbons were was detected in the groundwater samples collected from CPTI and CPT3. In
<br /> August 2005, ATC supervised the installation of four groundwater monitoring wells (JLM16,
<br /> JLM17, JLM18, and JLM19). Petroleum hydrocarbons were not detected in groundwater samples
<br /> collected from these wells. Shallow groundwater flow beneath the site generally flowed in a radial
<br /> pattern towards JLM3 on August 30, 2005. Refer to ATC's Subsurface Investigation Report, dated
<br /> November 7, 2005, for additional information.
<br /> • SAMPLING ACTIVITIES
<br /> On March 1, 2006, groundwater samples were collected from monitoring wells JLM3, JLM4, JLM5,
<br /> and JLM12 through JLM19. Prior to collection of groundwater samples, the depth to water was
<br /> measured in the wells and the pH, electrical conductivity, and temperature were measured in
<br /> groundwater purged from the monitoring wells and recorded. Approximately three well casing
<br /> volumes were purged from each monitoring well prior to sampling. The wells were allowed to
<br /> recover and samples were collected from each well using disposable polyethylene bailers.
<br /> The groundwater samples collected from each well were submitted to State-certified Argon
<br /> Laboratories (Environmental Laboratory Accreditation Program Certification. No. 2359) in Ceres,
<br /> California for chemical analyses of total petroleum hydrocarbons quantified as gasoline (TPHg) and
<br /> total petroleum hydrocarbons quantified as diesel (TPHd) utilizing EPA Method 8015M; and
<br /> benzene, toluene, ethylbenzene, and xylenes (BTEX), methyl tertiary butyl ether (MTBE), ethyl
<br /> tertiary butyl ether (ETBE) di-isopropyl ether (DIPE), tertiary amyl ether (TAME), tertiary butyl
<br /> ether (TBA), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) utilizing EPA Method
<br /> 8260B. Groundwater well purge and sample logs are included in Attachment 1.
<br /> GROUNDWATER FLOW DIRECTION
<br /> Water level measurements collected from JLM3, JLM4, JLM5, and JLM12 through JLM19 (Figure
<br /> • 2) on March 1, 2006, ranged from 23.35 to 24.53 feet below the tops of the well casing elevations.
<br /> The water level data were used to develop the groundwater elevation contour map shown in Figure 3.
<br /> s:\enviromenml\28589\reports\20061QR.doe 2
<br />
|