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URS
<br /> Mr. Ross Atkinson
<br /> Regional Water Quality Control Board—Central Valley Region
<br /> May 20, 2011 Page 4 of 10
<br /> In addition, San Joaquin County Public Works Department provides an online groundwater map
<br /> showing the gradient and depth to groundwater for the spring(April)or fall(October)seasons for
<br /> selected years from 1998 to 2010 at the following website: http://www.simap.org/groundwater/. The
<br /> gradient for all dates are either to the northeast or to the east-northeast at the location of the World
<br /> Enterprises site.
<br /> Analytical Results
<br /> Soil. The results for total petroleum hydrocarbons and semi-volatile organics were found to be below the
<br /> reporting limit of the analyses. Acetone at 5.8J micrograms per kilogram(µg/kg) was the only
<br /> constituent detected for the VOC analysis. Table 3 summarizes the soil sample metals results.
<br /> Groundwater. The following inorganic parameters were analyzed each quarter from December 2006
<br /> (4Q06)to March 2011 (1Q11): TDS, aluminum, arsenic, barium, cadmium, chromium, cobalt,copper,
<br /> iron,manganese, lead,mercury,nickel, silver,selenium, thallium,vanadium, and zinc.
<br /> The following eight inorganic constituents were identified in the RWQCB letter dated
<br /> February 20, 2007, at concentrations above RWQCB's water quality goals: TDS, aluminum, arsenic,
<br /> barium, iron, lead, manganese, and nickel. The following bulleted items summarize the results of these
<br /> eight constituents for the quarterly monitoring activities to date.
<br /> ® TDS was detected within 54 of the 54 samples (18 events for 3 monitoring wells). For MW-1,
<br /> the highest concentration was 1,730 milligrams per liter(mg/L) (4Q06). For MW-2,the highest
<br /> concentration was 2,520 mg/L(4Q08 and 4Q09). For MW-3, the highest concentration was
<br /> 1,220 mg/L(4Q09).
<br /> ® Aluminum was detected within 6 of the 54 samples. For MW-1, aluminum was detected during
<br /> 3 of the 18 events with the highest concentration of 0.459 mg/L(4Q08); for MW-2, it was
<br /> detected during 2 of the 18 events with the highest concentration of 0.462 mg/L (4Q08), and for
<br /> MW-3, it was detected during 1 of the 18 events with the highest concentration,of 1.44 mg/L
<br /> (4Q08). Three of the 54 samples were found to be above the report limit of<0.2 mg/L where all
<br /> of the samples collected during the 4Q08 event were above the reporting limit.
<br /> ® Arsenic was detected within 23 of the 54 samples. For MW-1, arsenic was detected 18 of 18
<br /> events with the highest concentration of 0.0358 mg/L(4Q06). For MW-2, it was detected 4 of
<br /> 18 events with the highest concentration of 0.00576)mg/L (4Q06). For MW-3, it was detected
<br /> I of 18 events with the highest concentration of 0.00326 mg/L (4Q06).
<br /> ® Barium was detected within 54 of the 54 samples. For MW-1,the highest concentration was
<br /> 0.763 mg/L (4Q06). For MW-2,the highest concentration was 1.77 mg/L(4Q06). For MW-3,
<br /> the highest concentration was 0.209 mg/L (4Q08).
<br /> ® Iron was detected within 36 of the 54 samples. For MW-1, iron was detected 17 of 18 events
<br /> with the highest concentration of 3.62 mg/L(4Q06). For MW-2, it was detected 18 of 18 events
<br /> with the highest concentration of 26.2 mg/L (4Q08). For MW-3, it was detected 1 of 18 events
<br /> with the highest concentration of 1.05 mg/L (4Q08).
<br /> H:AWprocess\25532\WorldGuterpriseAClosureA05201].doc
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