COMPLIANCE INFO_EW-5 INSTALL PERMIT PACKAGE 2/14/25

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WELL INSTALLATION AND INTERIM REMEDIAL ACTION REPORT www.arcadis.com FINAL_Forward CHCF (CDCR) Well Installation Report_10182024 13 between approximately 11 and 640 feet from the extraction well, were used to assess changes in water level to the shallow and intermediate hydraulic units during the test. The hydraulic test results are summarized in Table 9 and the response hydrograph is presented in Appendix H-1. Extraction well CDCR EW-4 exhibited a maximum drawdown of approximately 38.24 feet after 8 hours, which was approximately 0.8 foot below the top of the upper screen interval. The hydrograph indicates stabilization of the drawdown trend, indicating that the test rate was a sustainable pumping yield. Hydraulic influence was indicated in both the shallow and intermediate WBZs for monitoring wells AMW-58S, AMW-58M, AMW-22, AMW-59S, and AMW-59M, and extraction well CDCR-EW-2. A graph of the radius of influence and transducer hydrographs are presented in Appendices H-2 and H-1, respectively. The results indicated a hydraulic radius of influence up to 640 feet from the pumping well for an 8-hour pumping period. The observation well data were barometrically compensated and imported to AQTESOLV™, and curve matching to the dataset performed (i.e. the point data were fitted with a curve that best matched the entire data set). Assessment was possible for datasets from the pumping well, extraction well CDCR-EW-4, and monitoring wells AMW-58S (screened in shallow WBZ) and AMW-58M (screened in intermediate WBZ). Estimates of aquifer transmissivity and hydraulic conductivity were calculated. The test results are presented in Table 10, and AQTESOLV™ output files are presented in Appendix H-3. For the constant rate test, data curve matching was performed using Theis (1935) and Cooper-Jacob (1946) solution methods for unconfined aquifers and Hantush (1960) for leaky aquifers. The step test data were also analyzed and included as part of this hydraulic parameter assessment for transmissivity and hydraulic conductivity using the Theis (1935) step test curve solution. Typically, all hydraulic parameters derived using the pumping well were approximately one to two orders of magnitude lower than those derived from the observation wells. This indicates the influence of well losses on the pumping well dataset. The observation well hydraulic results were considered to be more representa tive of the aquifer parameters and, therefore, were preferentially used for aquifer parameter calculations. Using only the monitoring well data, the hydraulic conductivity was indicated to range between 149 and 334 ft/day (5.2 x 10-2 to 1.2 x 10-1 cm/s), with an average hydraulic conductivity of 250 ft/day (5.4 x 10-2 cm/s), which is indicative of medium to coarse sand and/or sand and gravel mixes (Kruseman and de Ridder 2000). Storativity for the monitoring wells was between 1.9 x 10-3 and 1.7 x 10-1 cm/s, with an average of 3.7 x 10-2 cm/s, which is indicative of an unconfined or leaky aquifer system. Based on the monitoring well data the aquifer transmissivity2 was indicated to range between 4,456 and 10,008 ft2/day, with an average transmissivity of 7,505 ft2/day. Hydraulic conductivity estimates were also calculated for gain size sample data (Appendix H-4) collected from depths adjacent to the screen zones of CDCR-EW-4. The grain size data were imported and assessed using HydrogeoSieve v2.1 (Devlin 2015). The hydraulic assessment data are presented in Table 11, the output files from the analysis are presented in Appendix H, and the laboratory sieve data that were used are presented in Appendix C. Hydraulic conductivity calculated from the grain size data ranged between 18.8 and 62.9 ft/day (6.6 x 10-3 to 2.2 x 10-2 cm/s), with an average of 44.7 feet/d (1.6 x 10-2 cm/s), which is indicative of fine to medium sand and sand and gravel mixes. The hydraulic conductivity estimates calculated using the grain size data are lower than the aquifer testing estimates. The aquifer testing results are considered more accurate because the soil samples are locally derived from the borehole and the aquifer test indicates the entire response of the aquifer. 2 Transmissivity equals hydraulic conductivity multiplied by saturated permeable thickness.