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Section 1 Introduction and Background respectively. Additional soil descriptive,physical, and chemical properties are provided as Appendix A of this report, for further reference. 1.2.2 SHALLOW GROUNDWATER OCCURRENCE Groundwater elevation data were obtained froin both the existing WWTF groundwater monitoring program (MW-1 through MW-3)and from the California Department of Water Resources (DWR). This information was subsequently imported into a geographic information system(GIS) in order to graphically evaluate groundwater elevations and flow direction within the project area. Figure 1 illustrates groundwater elevation contours for the fourth quarter of 2005 and represents the typical reported groundwater flow direction in the vicinity of the treaiinent ponds,which has historically been towards the southwest. Figures 2 and 3 represent groundwater elevation obtained from the DWR for periods extending from January through June and July through December 2005, respectively. These figures indicate that regional groundwater flow direction is predominantly towards the south and south southeast, approximately 45 to 90 degrees to that of historic groundwater contours in the vicinity of the treatment ponds. It should be noted however,that the spacing of existing monitoring wells MW-1, MW-2, and MW-3 are such that accurate interpretation of groundwater flow direction may not be possible. Additionally,the well completion details for the DWR monitoring program is not known and therefore reported groundwater elevations may not be representative of first recoverable groundwater in the area. Variations in the depth to first recoverable gr urndwater was similarly assessed using the existing WWTF groundwater monitoring network and a DWR well,which was reportedly located within 1100 feet of the disposal fields(Figure 5). Based on these sources of information the depth to groundwater at the wastewater treatment pon s and disposal fields is expected to occur between approximately 100 to 130 feet bgs and similar to that reported by ENGEO for monitoring wells constructed just to the east of the WWTF and at a proposed disposal area expansion site. Additionally,these monitoring data(WWTF ells) indicate that the depth to groundwater can vary seasonally and up to approximately 5 feet. As such,these seasonal variations in groundwater elevations should be accounted for when designing the new monitoring wells. March 2006 Lockeford CSD 1.2 Groundwater Monitoring Well Installation Workplan