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 11 5.2 CDCR Extraction Well Hydraulic Testing Hydraulic tests were conducted at newly installed extraction wells CDCR -EW-3 and CDCR-EW-4. The tests included a step test and constant rate test at each extraction well location. Field data sheets associated with the hydraulic tests are included in Appendices D-2 through D-4, and data analysis of the hydraulic tests is included in Appendix G for extraction well CDCR-EW-3 and Appendix H for extraction well CDCR-EW-4. 5.2.1 CDCR-EW-3 Hydraulic Testing Data Analysis Step and constant rate hydraulic tests were conducted on extraction well CDCR-EW-3, which is screened across permeable sections of the shallow and intermediate WBZs on the CDCR property (Table 1, Figures 1 and 2). Step testing was performed by extracting groundwater from extraction well CDCR-EW-3 at incrementally increased flow rates while also recording changes in water levels from the well. The step testing results are presented in Table 2 and on Figure 3 and field data sheets are presented in Appendix D-2. Step testing was conducted at rates of 5.1, 10.0, and 20.3 gpm. Additionally, a fourth step was added to the data analysis using hydraulic response data derived from the constant rate test. The step test analysis indicated a specific capacity between 1.8 and 3.7 gallons per foot of drawdown (Table 2). The specific capacity trend was consistent (Figure 3), indicating that the aquifer had not been stressed as part of testing and maximum well capacity had not been reached. This suggested that a maximum well capacity greater than 24.2 gpm could be achievable. Based on extrapolation of the drawdown curve, a pumping rate of 30 gpm could theoretically be achievable, with a well pumping water level predicted at approximately 2.5 feet above the upper screen interval. Constant rate testing was then conducted with extraction well CDCR-EW-3 pumped at a rate of 24.1 gpm for approximately 8 hours and groundwater recovery monitored overnight. The hydraulic test design is presented in Table 4, and field data sheets are provided in Appendix D-3. A monitoring well network of 10 wells, located between approximately 11 feet and 1,535 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 6 and the response hydrograph is presented in Appendix G-1. Extraction well CDCR-EW-3 exhibited a maximum drawdown of approximately 16.0 feet after 8 hours, which was approximately 4.5 feet above the top of the upper screen interval. The hydrograph indicates that stabilization of the drawdown trend occurred, indicating that the test rate was a sustainable pumping yield. Hydraulic influence was indicated in both the shallow and intermediate WBZs in monitoring wells AMW-61S and AMW-61M, AMW- 60M, AMW-50M, and AMW-22. A graph of the radius of influence and transducer hydrographs are presented in Appendices G-2 and G-1, respectively. The results indicated a hydraulic radius of influence up to 580 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(s) 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-3, and monitoring wells AMW-61S (screened in shallow WBZ) and AMW-61M (screened in intermediate WBZ). Estimates of aquifer transmissivity and hydraulic conductivity were calculated. The test results are presented in Table 7, and AQTESOLV™ output files are presented in Appendix G-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.