Laserfiche WebLink
Groundwater Monitoring Plan 3 <br /> Regional groundwater flow in this area has been reported to the north, northwest, and northeast <br /> (San Joaquin County Flood Control and Water Conservation District, 1999). Groundwater flow <br /> direction at the facilities has not been established to date. <br /> 2.2 Local Geology and Hydrogeology <br /> Shallow soil encountered at the Lathrop facility in the upper 10 to 15 feet consist primarily of <br /> interbedded unconsolidated fine-grained sands composed of silty sand, clayey sand, and poorly <br /> graded sand. A hardpan layer was observed at approximately 12 to 16 feet below ground surface <br /> (bgs), and may not be laterally continuous. Groundwater is present at approximately 21 feet bgs, <br /> and static borehole groundwater levels were observed between 18 and 19 feet bgs (Brown and <br /> Caldwell,June 2001). <br /> At the French Camp facility, soil within the upper 31 to 37 feet consist of interbedded <br /> unconsolidated fine-grained sands composed of silty sands, clayey sands, and/or poorly graded <br /> sands), silts, and sandy clay. Groundwater is present at approximately 29 feet bgs, and static <br /> borehole groundwater levels were observed between 26 and 28 feet bgs. <br /> 3.0 MONITORING WELL INSTALLATION AND SAMPLING <br /> This section describes the field sampling activities associated with the monitoring well installation <br /> activities at both the Lathrop and French Camp facilities. <br /> 3.1 Site Preparation and Health and Safety <br /> Site-specific Health and Safety Plan (SSHP) that details safe working practices will be prepared and <br /> will be on-site during investigation activities. <br /> Groundwater monitoring well installation permits will be obtained from the San Joaquin County <br /> Public Health Services Environmental Health Division (EHD) prior to drilling. The proposed will <br /> locations will be marked and Underground Service Alert (USA) will be notified at least 48 hours <br /> prior to drilling. Each boring will be hand augered to a minimum of 5-feet bgs to avoid damaging <br /> shallow subsurface utilities. The actual well locations may be adjusted to accommodate field <br /> conditions. <br /> 3.2 Soil Borings and Monitoring Well Installation <br /> Three groundwater monitoring wells will be placed around the stockpile area at each facility as <br /> shown in Figures 2 and 3. As noted previously, the actual locations will depend on access <br /> restrictions posed at the site and the location of underground utilities. Based on preliminary <br /> information, the depth to groundwater is approximately 28 feet bgs at the Lathrop facility, and 32 <br /> feet bgs at the French Camp facility. <br /> P:\wp\jobs\20587\CAO GW Workpla .doc—DCN 12495 January 2002 <br />