Committee approves rehabilitation of National City Well 3; staff says work could pay for itself within a year

The Engineering and Operations Committee on May 7 approved staff’s recommendation to rehabilitate National City Well Number 3 and to reallocate capital funds to pay for immediate work. Staff awarded the low responsive bid to Lane Christensen Co. for $310,959.79 and requested $67,760 from fiscal-year 2024–25 capital contingency and $243,199.79 from the street improvement project to cover the cost.

The authority’s operations staff reported that Well 3, part of the National City well field and supplying roughly 10% of Sweetwater Authority’s water portfolio, had shown a steady decline in production from about 700 gallons per minute to roughly 450 gpm. Operators had partially throttled the pump to avoid drawing air and risking pump damage. Chester (presenting staff) said the well had been rehabilitated in 2022 for a mechanical vibration issue, and staff’s investigation suggests mineral scaling and gravel-pack clogging have reduced flow since then. "We put Well 2 on, produces a little bit less, about 20 gallons per minute less, in its absence," Chester said when describing operations while Well 3 was offline.

Staff issued a request for qualifications and received two bids; Lane Christensen submitted the low responsive quote. Staff said the rehabilitation scope includes pulling the well, mechanical cleaning, a chemical treatment intended to remove iron and mineral scale in the gravel pack, and a video survey before and after work. Staff cautioned there is no guaranteed post-cleaning flow; the contractor can follow procedures to increase the chance of improvement, but the final flow rate will be known only after the well is returned to service.

Engineers presented an estimate of potential water supply savings: if cleaning raises Well 3 output from 450 gpm to 600 gpm, the increased production would amount to about 242 acre-feet annually. Staff calculated that, at San Diego County Water Authority replacement cost and estimated power/chemical costs, producing that volume locally rather than purchasing it elsewhere yields significant savings; staff said the project could pay for itself in roughly 347 days under the assumptions used in their analysis. Committee members asked about prior cleaning work, warranties and inspection intervals; staff said previous cleaning focused on mechanical issues and that chemical treatment for the gravel pack was not part of the 2022 scope. The committee approved the motion by roll call; Director Castaneda, Director Cox and Director Martinez voted yes and the motion passed unanimously.