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<br /> A S S O C I A T E S I N C
<br /> Groundwater Flow Direction
<br />' Water level measurements were collected from wells MW1 through MW10, and CW on March
<br /> 6, 2003 Water levels ranged from 24 13 to 27 72 feet below the tops of the well casing
<br /> elevations, representing an average increase in the water table elevation of approximately 0 23
<br />' feet since December 2002 The water level data were used to develop the groundwater elevation
<br /> contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in
<br /> the uppermost aquifer beneath the site flowed towards the northeast The average hydraulic
<br /> gradient on March 6, 2003 was calculated to be 0 007 ft/ft or approximately 34 ft/male A
<br /> summary of groundwater monitoring data is presented in Table 1
<br />' REMEDIATION SYSTEM MONITORING ACTIVITIES
<br /> Vapor Extraction System Monitoring
<br /> The installation and startup of the vapor extraction system located at the site is detailed in ATC's
<br />' Remediation System Installation Report for the Farmer Property, 610 North Hunter Street,
<br /> Stockton, California, dated April 8, 2003 After the modifications described in the Remediation
<br /> System Installation Report were made to the system, ATC started the vapor extraction system on
<br /> December 19, 2002 During this reporting period, ATC personnel monitored the vapor extraction
<br /> system on January 3, 10, 17, and 24, February 13, 21, and 28, and March 14, 21, and 27, 2003 The
<br /> vapor extraction system was off-line from March 11 through March 26 due to an electrical short
<br /> circuit
<br /> Parameters monitored in the field included vapor extraction flow rates, induced vacuum responses
<br />' at on-site wells if applicable, hydrocarbon vapor concentrations with an organic vapor monitor,
<br /> groundwater extraction rate, total groundwater discharged to the City of Stockton sewer service,
<br />' and total hours of system operation Field monitoring data is contained in Attachment 3
<br /> On January 24, February 28, and March 27, 2003, ATC collected vapor samples from wells VW1
<br /> and V W2 and from the influent and effluent vapor streams of the vapor extraction system The
<br /> samples were transported under chain-of-custody documentation to SunStar Laboratories, Inc
<br /> (ELAP #2250) in Tustin, California and were analyzed for VOCs by EPA method TO-14
<br /> On January 10, February 13, February 28, and March 21, 2003, ATC collected water samples from
<br /> the groundwater treatment and discharge component of the vapor extraction system Water
<br /> I samples were collected from the influent and effluent of the groundwater treatment system and
<br /> transported under chain-of-custody documentation to Argon Labs for analysis An influent water
<br /> sample was not collected on March 21, 2003 because the vapor extraction system was off-line from
<br /> March 11 through March 26 due to an electrical short circuit The water samples were analyzed for
<br /> TPHg by EPA method 8015, BTEX by EPA method 8020, and MTBE, TAME, ETBE, DIPE,
<br /> TBA, 1,2-DCA, and EDB by EPA method 8260
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