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r Kennedy/Jenks Consultants r 1 Wells and soil borings have been drilled to characterize the first-encountered groundwater beneath the facility and two northern parcels. Groundwater is generally encountered at depths of less than 10 feet bgs, so wells and borings have been drilled to a maximum of 16.5 feet bgs. The well construction logs indicate the well borings were sampled with an 18-inch long split spoon sampler starting at about five feet bgs. The soil borings were drilled using a continuous coring system (Condor 2002). ' Generally, the subsurface consists of a mixture of silty or clayey layers. Well-graded sand was encountered in well GW-6 from about 11 feet bgs to the total depth of the boring but this sand layer was not observed in nearby boring KB-8, or in well GW-5 or GW-7. Poorly graded sand was encountered in monitoring wells GW-9, GW-10, GW-11, and GW-12. In many of the soil r borings, the upper eight to nine feet consisted of silty sand and in borings KB-4 and KB-6 the entire 10 feet of the boring consisted of silty or well-graded sand. The clay and silt soils logged in the soil borings were very stiff to stiff and typically had low to no plasticity. r 1, 2.2.6 Facility Hydrogeology n In the soil borings, the first-encountered groundwater was typically observed at the base of the L silty sand just above a deeper clay or silt layer. Groundwater was also observed in the clay and silt layers if sand was absent. The stabilized groundwater levels in the wells indicate that the shallow aquifer is unconfined. 2.2.6.1 Groundwater Gradient C Groundwater monitoring data collected between 2004 and 2008 indicate that the groundwater L flow direction at the facility is generally from east to west, at a gradient of approximately 0.0009 feet per foot. The small gradient magnitude is a function of the proximity to the Delta and the flat local topography. Since the installation of wells GW-8 through GW-14 in July 2009, monthly groundwater elevation contouring indicates that the groundwater flow at the facility may change direction from a northwest to southwest gradient, depending on current irrigation practices L and/or flows of the nearby Mokelumne River. Groundwater elevations measured at the existing and proposed additional wells will further our understanding of groundwater gradient and velocity at the facility. The groundwater elevations presented in Table 3 are measured relative to well apron elevations L, surveyed in August 2009. Figures 5 and 6 display the groundwater elevation gradients for the monitoring dates 18 August 2009 and 15 September 2009, respectively. Groundwater hydrographs for monitoring wells GW-1 through GW-7, for the monitoring period March 2003 through September 2009, are presented on Figure 7. Hydrographs for monitoring wells GW-8 through GW-14 are not presented because these wells were recently installed. 2.2.6.2 Facility Groundwater Quality Condor has monitored the groundwater quality at the facility on behalf of Sutter Home since 2002. Kennedy/Jenks sampled the newly installed monitoring wells GW-8 through GW-14 on 23 July, 18 August, and 15 September 2009. Groundwater data collected for monitoring wells GW-1 through GW-14 are provided in Table 3. The analytical results from the reconnaissance groundwater samples collected from the two northern parcels in Page 6 Hydrogeologic Investigation and Groundwater Sampling and Analysis Work Plan, Sutter Home Lodi Winery, Lodi, California - g:Yx 9rcuplaEianyob'A610B65005.06 sNkrMne109-repo *&W 116h ftv planWAx