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Council weighs pilot deep-well drilling at Martin’s Flat; city staff say geology is promising
Summary
Engineers presented Hanson/Loosch findings that Martin’s Flat has favorable geology for a deep production well into Navajo Sandstone; a pilot borehole and zone testing could cost $1.8–$2.0 million and additional costs would follow to complete a production well.
Cedar City engineering staff recommended moving forward with more aggressive testing at Martin’s Flat after a consultant identified the site as one of the better subsurface locations in Cedar Canyon.
Jonathan Stathis of the city engineering department summarized the geology and prior test work. A 2023 test borehole reached about 818 feet and encountered bedrock (Entrada Formation); consultants Hanson & Loosch estimate that drilling to roughly 2,000–2,100 feet would penetrate about 400 feet into the Navajo Sandstone, a more porous formation that typically yields higher quantity and better-quality water.
Stathis said the 2023 test well produced about 250 gpm on a small test pump and that prior tubing/casing and open-hole conditions complicated testing. He recommended a planned sequence: drill a larger pilot hole (roughly 12¼-inch) to about 2,000 feet, conduct zone testing in both the Entrada and the Navajo zones, then—if quantity and quality are acceptable—ream and complete a production-sized bore and install a production pump.
Costs and tradeoffs: Consultants’ cost estimates for the pilot/drill-only phase were roughly $1.8 million; a production pump, motor and associated piping and site work could add about $1.5 million (estimates in the presentation). Stathis said the pilot cost does not include reaming to final pump diameter; that would add further expense. Water-quality results from the existing test log showed total dissolved solids (TDS) above 800 mg/L and elevated aluminum and iron in the shallower zones; Hanson & Loosch expect TDS and constituents to improve in the deeper Navajo Sandstone but recommended laboratory testing of deep samples before committing to production.
What the council discussed: Council members asked about pipeline and connection logistics; staff said the proposed well site is a few hundred yards from existing city pipeline and that crossing Coal Creek and under the highway would be needed in the preferred alignment. Staff noted that the city already holds surface water rights and some rights north of the Hurricane Fault that could be converted for use if the well proves viable.
Budget context and next steps: Council staff noted about $1.9 million previously budgeted for a Martin’s Flat production well; that sum could cover the drill pilot and a portion of completion work. Stathis told the council the recommended next step is to issue an RFP for drilling the pilot hole and return with firm bids and a schedule. Council members directed staff to place the item on next week’s action agenda for a vote of support to proceed with the procurement step.
