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Mantta-Quarterly Groundwater Monitonng _ Page 3 <br /> 3.0 GROUNDWATER GRADIENT <br /> SRK retained the services of Cella Barr Associates to provide elevations at the top of well heads <br /> relative to a known datum, and the locations of the wells relative to on-site structures This <br /> information is provided on Figure 1 (located in the pocket at the back of this report). Static <br /> water levels were measured on April 6, 1992 using a Solmst Water Level Indicator Copies of <br /> the static water levels are provided in Table 1 <br /> TABLE 1: Static Water Levels <br /> ' November 1991 and April 1992 <br /> Now n9w 24,1M Apni& <br /> SRS SRIF ; <br /> Sim ]- 39 <br /> MWi-MM M'�� M Km �� M�� fi <br /> FstatLcater Level 2345 23 75 2375 2120 2152 <br /> Well Depth 38 39 39 38 39 <br /> Screened Interval 23 -38 24 - 39 24 - 39 23 - 38 24 -39 <br /> r NOTES <br /> Static Water Levels Measured from top of well casing using a Solinst Water Level Indicator <br /> Using the above information, the groundwater gradient was determined through an orthographic <br /> ' construction known as a 3-point Problem (Davis, G H , 1984, Structural Geology of Rocks and <br /> Regions John Wiley & Sons, pp 210) Solving a 3-point Problem requires elevation control for <br /> at least three points that lie on a common plane, in this case the groundwater surface The <br /> jelevation control was obtained by subtracting the static water levels (measured from the top of <br /> well casings) from the elevations of the well heads (referenced to the USGS Bench-Mark D-83, <br /> Brass Cap on the top step of Legion Hall, south side of Yosemite Avenue, 1-1/2 blocks east of <br /> Main Street Elevation 38 051 feet) It should be noted that the groundwater elevations vaned <br /> by only a few tenths of feet With this in mind, the groundwater gradient trends N17E, with a <br /> true dip of 2°NE <br /> ' 4.0 GROUNDWATER SAMPLING <br /> Three addittonal well Ldsing volumes were purged from with of the SRK monitoring using the <br /> 4-inch submersible pump and braided PVC tubing The analytical groundwater samples were <br /> collected from the end of the PVC tubing in laboratory grade sampling containers These <br /> samples were collected after the pH, temperature, and conductivity had stabilized "Stabilized" <br /> is defined as three consecutive readings within 15% of one another Copies of the Field <br /> Groundwater Purging/Sampling Logs are provided in appendix A Copies of the Geologic Logs <br /> and Monitoring Well Construction Diagrams are provided to Appendix B <br /> 3250 22\a-trlvw 22 Sleffen Robertson and Kirsten <br />