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Final March 2004 On-Post Quarterly Groundwater Monitoring Report
Section 3 - Weather Station and Transducer Data
Fifteen wells, CS‑1, CS‑10, CS‑11, CS‑MW1‑CC, CS‑MW2‑CC, CS-MW4‑LGR, CS‑MW9-LGR, CS‑MW9‑BS, CS‑MW11A‑LGR, CS-MW11B‑LGR, CS-MW12‑CC, CS‑MW16‑LGR, CS‑MW16‑CC, CS-MW18‑LGR, and CS‑MW19‑LGR are equipped with transducers to continuously log groundwater levels. Two weather stations, one adjacent to well CS‑MW16‑LGR in the north-central region of CSSA and one in the southeast corner of CSSA adjacent to AOC‑65, record weather data including precipitation and other weather characteristics. The data are compared to identify trends in groundwater recharge. Precipitation data collected from the weather station at well CS‑MW16‑LGR between October 5, 1998, and March 10, 2004, are shown in Figure 3‑1, along with groundwater elevation data from the transducer at CS‑MW16‑LGR. Well CS‑MW16‑LGR was originally completed as an open borehole through the LGR, BS, and CC Formations. In July 2002, this well was re-completed with a 25‑foot screen interval within the LGR. Figure 3‑1 illustrates the rapid rise in groundwater elevation within well CS‑MW16‑LGR immediately following a rain event. Due to a technical malfunction of the transducer, CS‑MW16‑LGR groundwater elevation data from the June 2001 monitoring event through the September 2001 monitoring event are estimated in Figure 3‑1. On May 21, 2002, the transducer was removed from CS‑MW16‑LGR for telemetry testing and was returned to the well on June 6, 2002. Transducer data are also estimated from June 20, 2002 through July 10, 2002, due to the well construction upgrade of CS‑16 to CS‑MW16‑LGR.
Overall, groundwater levels in all three formations throughout CSSA increased an average of 27.73 feet between December 8, 2003 and March 5, 2004. During this period there were 30 rainfall events with a total precipitation of 6.35 inches. Rainfall events during this quarter occurred mainly in January and February, with 1.35 inches of rain on January 16, 2004, and 0.92 inches of rain on February 24, 2004. During the previous quarter when groundwater levels decreased 32.85 feet, there were 22 rainfall events with a total precipitation of 2.79 inches. For comparison of all events, Table 3-1 shows the total precipitation received each quarter, average groundwater elevations in each formation, and the average groundwater elevation change in each formation, whether increase or decrease.
In Figure 3-2, groundwater elevation data for the CS‑MW9 cluster wells were plotted in comparison to the daily precipitation as measured from the meteorological station at CS‑MW16‑LGR. Well CS‑MW9‑CC groundwater elevation data from December 2002 to March 2004 do not appear in Figure 3-2 because of battery failure in the transducer. This transducer will not be repaired, but a supervisory control and data acquisition (SCADA)-compatible transducer will be installed in the future. Transducer data collected from wells CS‑MW16‑LGR and CS‑MW4‑LGR are shown in Figure 3‑3. Results for well CS‑MW4‑LGR are missing from March 23, 2002 to September 3, 2002 due to a technical malfunction of the transducer, and those values have been interpolated in the chart. September 2003 to March 2004 data do not appear in Figure 3‑3, also due to battery failure in the transducer. This transducer will not be repaired due to pending installation of the SCADA-compatible transducer.