MVWD Crews Fix Another Major Line Break

By VERNON ROBISON

The Progress

Line crews at Moapa Valley Water District (MVWD) scrambled to make repairs on a major water distribution pipeline on Wednesday afternoon, Nov. 30. The line burst open in a remote area between Glendale and Logandale. The 24” ductile iron pipe is the main line supplying most of Logandale and Overton.

The alarm indicating a major leak in the system went off at 1:25 pm on Wednesday. It was initially received by MVWD Serviceman Mica Leatham who was on call.

Leatham said that he immediately checked the district’s electronic Supervisory Control and Data Acquisition (SCADA) system and noticed a drastic increase in flow.
“We had suddenly gone from a flow of 500 gallons per minute to 3,000 gallons per minute,” Leatham said. “So we knew we had a big problem.”

Earlier in the day, a representative from an outside entity had been doing an inspection on a fire hydrant located in Logandale. The inspector had reportedly shut off flow through the hydrant too quickly which caused a pressure spike known as a water hammer. That spike is thought to have been the initial cause in the break.

But the line was already identified as a weak point in the system, according to MVWD Line Crew Supervisor Kiley Bradshaw. That section of pipe running nearly 12 miles from the Moapa tank, through the Muddy River narrows and on down to Wells Road in Logandale, has seen four leaks open up in the past year, he said.
“We have identified that the problem is not with the pipe’s manufacture, but rather in the way that pipe was installed,” said Bradshaw.

The pipe was installed in 1995. When installed correctly, ductile iron pipe should have a life cycle of at least 50 years, usually much more, Bradshaw said. But apparently a miscalculation was made on the corrosiveness of the soil in certain areas. Rather than covering the entire pipeline in the heavy plastic sleeve that keeps it protected from corrosion, it was left uncovered in large spans.

“The pipe through that whole area was exposed to the corrosive soil,” Bradshaw said. “That material will rust it out quick. The pipes just rust from the outside in and eventually you get breaks.”

A break to this crucial line can cause a major problem for water customers downstream. While there is a much smaller 12-inch line running parallel through the narrows which provides some redundancy, it doesn’t carry enough capacity to meet the demand of the lower valley communities. That leaves a set of three large storage tanks as the only source of water for the lower valley when this main line breaks. And in a pinch, those tanks can run low pretty fast, Bradshaw said.

“We were lucky this time because it is winter and the demand for water is relatively low,” he said. “The difference between winter and summer usage is about 2.5 million gallons per day. So if this happens in the height of summer things can run short pretty quick.”

Since the problem with the 24-inch line was identified last year, the district has begun to make plans to replace it. But with constantly escalating costs for such a big project, it will take some time to round up the funding.

In the meantime, district management has already taken several measures to prepare for and mitigate the situation.

One of those measures has been to build a significant inventory of parts needed to repair the line. MVWD General Manager Joe Davis has instructed staff to order enough parts to fix several breaks on that line at any given time. When a repair is made, the staff immediately orders replacement parts to keep them in stock.

“Joe has done a good job of keeping things supplied for us in a worst case scenario,” said Leatham. “We had all the parts we needed ready to go. There was no need to order anything which, in the current supply chain environment, might have delayed things quite a bit.”

In addition, beginning last June, MVWD crews have been installing a network of interconnects between the 24-inch line and its smaller 12-inch parallel pipe. That way, if the line breaks again, water can be easily routed around the broken section of pipe. Then water can continue to maintain levels in the Logandale tank.

“If we don’t have those interconnects, then the whole 24-inch line is down,” said Bradshaw. “And that is what feeds most of the lower valley. Without them, we would just have to go off the tanks for as long as that lasts.”

Leatham said that as soon as the alarm went out last week it was all hands on deck at MVWD.
“We have such good chemistry here and everybody knows what needs to be done and jumps in to do it,” he said. “It’s great when you’ve worked with guys for so long and everybody is just willing to stay and help out, even though it is cold and you’re all wet and you know it is going to be a long night.”

It took until about 11 pm on Wednesday night to get repairs made. Most of the nine person crew was able to go home at that point. But a couple of people had to stay behind until about 2 am to go through a long and careful process of charging the line back up again safely.

Thanks to these efforts and the careful preparations that had been made, no outages resulted from this major break.
“That is the way we like it,” said Bradshaw. “The best way is for our guys to be working late into the night while the folks in Logandale and Overton are sleeping peacefully, not even knowing anything happened.”

Joe Davis summarized an important message that the public could take from this scenario in two words: Don’t panic!
“This showed that with the interconnects, we have the capacity to feed water to the tanks in the lower valley under normal usage,” Davis said. “But we have seen in the past, if people get word of a problem in the water system, they panic and start to horde water in preparation of an outage. When that happens it is like a self-fulfilling prophecy and it draws down the tanks. Pretty soon everyone is out of water. But if everybody just continues with normal usage, it gives us time to make the repairs and everything is fine.”

Davis said that if future breaks occur, in times of higher water demands, customers may get a notice telling them to avoid outdoor watering for a time. If the public will simply comply with those requests without panicking, it could avert a more major outage, he said.