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' rWt0g1cal7ecknccsInc Page 5 Groundwater Monitoring Report ' Project No 770 2 February 7,2005 ' As req laboratory analytical required under AB2886 the laborato anal ical data and Geo Well files were submitted ' electronically to GeoTracker on December 30, 2004 - confirmation numbers 7627121567 and 5393635392 Geo Well files for 3rd quarter 04 were also submitted on December 30, 2004 — confirmation number 8605193912 2.0 FINDINGS AND DISCUSSION The results of the groundwater monitoring event indicate the following • The reversal of groundwater direction by 180' in the deeper aquifer for the April and May ' 2003 sounding events is anomalous to the historical data The deeper aquifer has been monitored by three wells (MW-104, MW-105 and MW-106) since June 2002 and the other events all displayed an easterly trend to groundwater direction It is noted that the ' gradients for these two events were higher than normal suggesting that off site production is influencing the aquifer A receptor well survey was completed for the site in January 2001 and two agricultural wells were identified approximately 1600 feet west of the site ' (see Map 1, Table i — Appendix D) If these wells were operated during the months in question, it is possible that the Marci site was within the cone of depression created by the well pumping The shallow aquifer did not reverse during this period and this may be M due to the domestic wells to the southeast of the site that may be screened shallower than the agricultural wells and exert a primary influence on the water table that is easterly • Diesel range petroleum hydrocarbons were detected in eight of the site's eleven monitoring wells • Well MW-5 contained 18,000 µg/1 diesel and this represents a significant decrease in ' magnitude from the last event, but similar to other previous events Well MW-5 remains the most severely impacted well S �y • Well MW-4 also experienced a marked increase in diesel concentrations since the June e,, �� 2004 event (from 4 6 to 3500 µg/l TPH-D) 1r ' • Gasoline range petroleum hydrocarbons (TPH-G) were detected in MW-5 (68-µg/1) and MW-7 (62-µg11) in this monitoring event Several wells have had at least one event in which TPH-G was detected • Trace amount of benzene is present in well MW-7 (0 79-µg/1) for this monitoring event, similar to concentration found in previous events ' • Deep wells MW-104 and MW-106 did not contain contaminant concentrations above the laboratory reporting limits TPH-diesel was detected (94 µg/1) in MW-105, sinular to other events when diesel was detected ' ' • The groundwater samples were analyzed for 1,2-dichloroethane and 1,2-dibromoethane in accordance with SJC/EHD's April 27, 2004 directive No well contained these contaminant concentrations above the laboratory reporting limit (0 5 ug/1) ' • Oxidation-Reduction Potential (ORP) measurements show that several monitoring wells are within the reaction depleted water caused by biodegradation of the contamination r