DPU Stabilizes Water Pressure On North Mesa

DPU crews work closely with Curb Services, a Los Alamos County contractor, to get pressure-regulating devices rebuilt in the water supply system on North Mesa. Courtesy/LAC

Los Alamos Daily Post

The water situation on North Mesa made some residents ask questions. Mainly, what’s up with the erratic pressure and is there enough water to satisfy the needs of future developments?

According to Department of Public Utilities (DPU) officials, the short answer is there is no water supply problem.

Furthermore, Deputy Manager Clay Moseley said, “We can definitely support more development. There will need to be an upgrade in some of the system piping infrastructure out there to support the new development, but that has been known since the concept was (first) proposed.”

The longer answer, he added, is that DPU is aware of the pressure issues, which became more evident when the Barranca Mesa #2 tank was taken offline for upgrades and painting.

“To take that tank offline, we had to reconfigure the supply system with valves to serve Barranca Mesa entirely through the feed lines from the Arizona Tank, which also serves both North Mesa and Barranca Mesa,” Moseley said. “The system capacity to do that is completely adequate (with ample excess capacity), but over the years, operators had open and closed both valves and pressure-regulating devices (PRVs) in such a way that two different pressure zones were crisscrossing, causing confusing pressure readings at locations such as Loma Linda, LAMS (Los Alamos Middle School), and the upper part of Barranca Mesa. This is where people have been experiencing fluctuating pressures since January/February, when we started all of the reconfigurations.”

Barranca Mesa Tank #2 is filled with pumps, he added, so it’s always a steady level of full, whereas other tanks, Barranca Mesa Tank #1 and the North Mesa Tank (Hawk Tank), are filled with system pressure through the PRVs, which must be functioning within a fine margin of pressure ranges.

“When Barranca Mesa Tank #2 was taken offline, we had all sorts of pressure issues from the increased demand through those two pressure zones feeding the mesas,” Moseley said. “We spent a lot of time chasing down the cross-over points and finally got them isolated from each other, but then we also had to spend a lot of time and work on repairing and upgrading the PRVs that control the pressures to the mesas – they see constant use and abuse, and it was time to invest in some pretty serious O&M (operations and maintenance) on them, which is no small task. We have only just completed this last task and are still making the fine-tuned adjustments to the system to perfect the pressure-to-use settings, which has been looking quite good over the past couple of weeks. We are also starting the engineering process to evaluate and incorporate yet another system improvement – altitude valves – to ensure we always have a more steady-state pressure situation with constantly full tanks.”

Moseley said since the PRVs are back to full functionality, things have been stable. Plus, when Barranca Mesa Tank #2 comes back in service it will add more pressure and supply resilience, redundancy and stability.

The upgrades being done to Barranca Mesa #2 Tank that required it to be offline include getting repainted and installing updated controls and communications. Moseley said the tank was put into operation in the 1950s and some of its parts were original.

It is expected to be back in operation in the next two to four weeks.

“There are a few final bugs to iron out, which is pretty customary for such a large project,” he said.
As far as what, if anything, residents on North Mesa could consider doing in response to the water pressure issue, Moseley said, “There is no need for residents to make any changes to water consumption.”

He explained since the repairs to the PRVs were done and the cross over points were found and taken out of the pressure equation, things are much more stable and there aren’t any wild fluctuations that bring DPU crews out.

“When the daily timeframe for maximum demand kicks in, starting each morning around 5:30 a.m., presumably when the schools, County Parks, and residents start irrigating (along with people getting ready for school and work), the system pressure regulating devices respond normally now to meet the pressure demands,” he said.

Moseley described this as “a big investigative project,” that DPU does prepare for in its budgets.

“We do a lot of budget analyses prior to setting each year’s operation and capital projects budgets,” he said. “In operations, we know we are going to need to spend money on O&M that is both planned and unplanned. There is a year-to-year pattern that we factor into each year’s budgets. The current budgets have the capacity to cover the costs of the O&M repairs to those big PRVs that control the flow to the mesas.”

Moseley said the project was something DPU had to investigate, observe, analyze, then decide to hire an expert to come in. DPU crews can perform certain procedures and repairs, but this particular project called for a major overhaul.

“It’s like when the transmission or motor on your car finally does something that makes you realize that you have to do something big to get it fixed,” he said. “In utilities operation, we pretty much plan on doing at least half a dozen of these types of unplanned O&M repair jobs each year. We have to plan for the ‘known unknowns.’ Taking Barranca Tank #2 did help us uncover perhaps a couple of other unknowns that we’ll be addressing as well, but again, it’s pretty standard stuff …”

All this effort appears to be paying off; Moseley said the pressure issues that have been dealt with since March have vanished these past two weeks.

DPU crews work closely with Curb Services, a Los Alamos County contractor, to get pressure-regulating devices rebuilt in the water supply system on North Mesa. Courtesy/LAC

DPU crews work closely with Curb Services, a Los Alamos County contractor, to get pressure-regulating devices rebuilt in the water supply system on North Mesa. Courtesy/LAC


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