Well Rehabilitation Project FY 26, Well Nos. 5718-1 and 5725-1

The Coachella Valley Water District’s (CVWD) Well Rehabilitation Project FY 26, Well Nos. 5718-1 and 5725-1 Project (Project) will rehabilitate two existing domestic wells to comply with the adopted Hexavalent Chromium (Cr-6) Maximum Contaminant Level (MCL). The wells currently exceed the Cr-6 MCL of 10 micrograms per liter (ug/L). Currently, wells 5718-1 and 5725-1 have Cr-6 concentrations of approximately 16 µg/L and 10.7 µg/L, respectively. The rehabilitation of these wells will eliminate the need to design and construct a new treatment plant(s) to comply with the adopted Cr-6 MCL. The rehabilitation and construction of the existing wells will be as follows: 1. Mobilize equipment to the well sites. 2. Remove the vertical turbine pump and associated components. a. Remove pump house. b. Inspect pump, motor, column pipe and line shaft. c. Provide inspection report and recommendation for repair. 3. Perform a Casing Inspection Log (CITM), well video survey, caliper log, and deviation survey. 4. Mechanically brush the inner well casing and screen to remove deposits from the inside walls and screen slots with a wire-line brush tool. 5. Perform well video survey. 6. Install a test pump with access tube for spinner survey and discrete zone water sampling tools (pump bowls set to approximately 350 feet). 7. Perform 4-hour pumping test on the entire well at varying rates. a. Perform spinner survey at each well b. Well 5718- 1: Collect discrete zone samples. Coordinate with CVWD to collect samples for water quality testing. c. Well 5725- 1: Collect discrete zone. Coordinate with CVWD to collect samples for water quality testing 8. Remove test pump equipment from well. 9. Fill bottom of well with clean gravel. a. Well 5718-1: Fill bottom of well with clean gravel to an estimated 1,250 feet below ground surface using tremie pipe and 5 ppm chlorine solution. Install a 10 foot thick bentonite layer from 1,250 feet to 1,240 feet below ground surface. b. Well 5725-1: Fill bottom of well with clean gravel to an estimated 1,220 feet below ground surface using tremie pipe and 5 ppm chlorine solution. Install a 10 foot thick bentonite layer from 1,220 feet to 1,210 feet below ground surface. 10. Reinstall test pump equipment 11. Perform 4-hour pumping test on the entire well at varying rates. a. Coordinate with CVWD to collect discharge water samples for water quality testing. 12. Perform water level recovery test. 13. Remove test pump and temporary discharge assembly. 14. Perform post-rehabilitation well video survey. 15. Select and place orders for permanent pumping equipment. 16. Disinfect the well and install permanent pumping equipment. 17. Re-install pump house, demobilize, and clean up the well site. The rehabilitation of the existing wells is anticipated to begin in or around December 2025 and last approximately 270 calendar days. The surrounding land uses consist of residential, open space, and roadways. Other domestic water wells in the pressure zone will be utilized during Project construction to avoid disruption of service to customers. The Project is not located within or adjacent to a conservation area associated with the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP). The sites are not subject to the CVMSHCP development mitigation fee because they are previously developed.