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Kennedy/Jenks Consuhants Section 3: Hydrogeology and Groundwater Monitoring 3.1 Groundwater Zones This section discusses the current understanding of the occurrence of groundwater beneath the Title 27 ponds. This discussion is based on analysis of boring logs from the installation of all wells in the network and detailed review of quarterly water level measurements and analytical results, as applicable. At least two zones have been identified in the vicinity of the Title 27 ponds, a shallow and intermediate zone. Site-wide, there is a "deep" zone, but this is applicable to larger-scale discussions of hydrogeology beneath the entire Site. The deep zone is of more regional extent and is likely present beneath the Title 27 ponds, but occurs deeper than first encountered groundwater in this location. There are no wells in the Title 27 groundwater monitoring network that currently monitor deep groundwater. It is important to note that all wells in the Title 27 groundwater monitoring well network have been installed in first encountered groundwater, regardless of the groundwater zone in which they were completed. The exception to this is Well MW-18, which was installed in the intermediate zone as a companion well to Well MW-17 installed in the shallow zone. 3.1.1 Shallow Zone In the vicinity of the Title 27 ponds, groundwater that is shallower than approximately 75 feet below ground surface (bgs) has been considered to be in the shallow zone. Groundwater monitoring wells that historically monitored the shallow zone include: Wells MW-10, MWA 1, MWA 7, and W-2. Well MW-10 was installed in April 2002 to a depth of 21.5 feet bgs.Well MW-10 yielded two quarterly samples, was noted dry in November 2002, then sampled again when water reappeared in August 2004 (full sample) and October 2004 (partial sample). Well MWA 0 has been noted as dry since January 2005. Well MW-11 was installed in April 2002 to a depth of 40 feet bgs. It yielded five full quarterly samples and one partial sample, and was first noted as dry in August 2003. Well MW-17 was installed in June 2005 as a replacement for Well MW-11, to a total depth of 65 feet bgs. Well MWA 7 yielded 15 quarterly samples and was first noted as dry in January 2009. Well W-2 was installed in 1985 to a total depth of 50 feet bgs.Well W-2 was sampled after its installation until it went dry. Water was noted again in Well W-2 in April 2002, and yielded 13 samples over a period of several years. Well W-2 was again noted as dry in June 2005. In addition to the four wells that historically monitored groundwater, three additional monitoring wells were installed in October 2006:Wells MWA 9, MW-20, and MW-21. These monitoring wells were installed to the target "shallow" depth of approximately 75 feet. Groundwater was not encountered in any of these wells and at the request of the RWQCB they were completed as dry wells. Work Plan for Improved Detection Monitoring Program Page 5 Musco Family Olive Company, Tracy, California g�er000WmmyobWV2oio4 o0_m=mom.ng.,eWft%o27_dmWW[aaomowlreporttext-09-26.doc