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quantities of groundwater. At least three Pleistocene-age buried river channels of the ancient Mokelumne River system have been identified to be present in the subsurface beneath Lodi (Shlemon, 1971). The oldest channel occurs at a depth of approximately 250 feet below ground surface (bgs) and is located within the Turlock Formation. A second channel has been identified at a depth of approximately 90 feet bgs and is located within the older Quaternary Alluvium. A third channel has been identified at a depth of about 40 feet bgs and is contained within the younger Quaternary Alluvium. These channel deposits reportedly dip to the west (Shlemon, 1971). Each of these buried river channels form significant aquifers beneath the city of Lodi (Henshaw, 2001). The direction of groundwater flow in the regional aquifers beneath the Lodi area is predominantly to the south, away from the Mokelumne River. Regional water level data indicate that the Mokelumne River is a very significant source of groundwater recharge to the regional aquifer system in the Lodi area(Eastern San Joaquin Groundwater Basin Management Plan, 2004). 3.2.2 Local Hydrogeolog A review of available soil boring logs for monitoring wells and water well drillers logs for municipal water supply wells indicate that the sediments beneath the LNC facility and the northern portion of Lodi consist primarily of a heterogeneous, interbedded mixture of unconsolidated gravels, sand, silts, and clays to a depth of at least 120 feet bgs (Figures 5 and 6). Several sand intervals have been identified from past investigations that appear to be relatively continuous beneath the northern portion of Lodi, although the thickness and permeability of the sand intervals vary significantly(Figure 6). These sand intervals generally tend to coarsen and thicken northward, towards the Mokelumne River and become thinner and finer-grained towards the south, away from the Mokelumne River. M ain\D:AEnvironmentaI\LN CV\10152007.wpd 10