College Place staff recommend targeted redevelopment to salvage Well 8 after drilling left fine sediment clogging screen

City of College Place officials on Tuesday heard from RH2 Engineering consultant Steve Nelson that Well 8 produced muddy, low flows during testing after drilling and appears “undeveloped” because fine sediment coated the installed well screen.

Nelson, who has worked on the city’s other wells, told the council the borehole reached about 800 feet and that the drilling encountered more interbedded siltstone than at earlier wells. “Much of the screen that was installed was still clogged with fine sediment from the drilling,” Nelson said. “It was never fully developed out of the well.”

The finding followed a temporary pumping test that produced about 50 to 200 gallons per minute (gpm) with substantial drawdown and little improvement after four hours of continuous pumping. Nelson said a recently received downhole video showed sediment still lodged in the screen and in the annular space outside the screen, which he said is impeding flow. He recommended detailed well-development work using specialized high-frequency pneumatic tools and pumping to dislodge and remove the fine material so the city can accurately measure the aquifer’s yield.

Why it matters: the city budgeted for Well 8 as part of its water-supply program. Public works staff and council members framed the decision as whether to invest additional funds to attempt to salvage an expensive drilling investment or to stop and look for other sites.

Nelson said the city has spent about $1.2 million to date on the Well 8 project and that consultants’ current estimates to perform substantial development, run new pumping tests and re-video the well are on the order of $100,000. He described the additional work as costly but within the original budget allocated for the well: “The cost estimate that I'm getting is in the hundred thousand dollar range, and that is to do the well development, run pumping tests, and get another video scan after the well development is done.”

Council members asked about viability thresholds. Nelson and city staff said the well’s present performance (roughly 50–200 gpm) is far below the city’s planning target and that a post-development yield around 700 gpm would make the site useful as at least a supplemental source. Nelson warned that even after development the aquifer itself might limit production, and that the work is needed to determine the true capacity.

City administrator Robert McAndrews and Public Works staff said they intend to ask a contractor experienced with these sediment-clogged basalt/rock completions to perform the development. Nelson said Gregory Drilling (the driller) performed only limited development hours and did not have the specialized tools or experience to fully develop the well; he said Shannon & Wilson and Holt Services were consulted and have proposed approaches and timelines. Holt Services’ representative (Janet Wilson) was referenced as available to start in about three to four weeks.

Council members also discussed contingency planning while the city tests Well 8. Mike Rosatello said the city is pursuing additional grant and state capital requests to backfill funding needs and that staff will begin parallel work to secure water-right “squares” for alternate well sites near Martin Airfield so the city isn’t left years behind if Well 8 fails to meet yield needs.

Council direction and next steps: staff said they will pursue a contract amendment or a new contract (through RH2 or a partner firm) for focused well development and additional testing, and will continue parallel water-right and siting work for a potential new well site. No formal council vote was recorded on Tuesday; staff will return to the council with contract documents and cost estimates if they proceed.

Ending: Council members stressed balancing the sunk cost already spent with the risk the well may not reach planning yields. Several members supported targeted development to determine the well’s usable capacity and asked staff to keep the council informed about costs, expert contractor selection and any needed budget adjustments.