Texas blackouts stress water & wastewater resiliency plans
As the saying goes, “Everything is bigger in Texas.” In 2017, the state was host to the wettest cyclone in the continental United States, Hurricane Harvey. Water and wastewater utilities showed tremendous resilience in the face of that cyclone.
And on Feb. 11, 2021, a 130 vehicle pile-up in Fort Worth, Texas, became a precursor and an omen for what was to come the following week.
Freezing rain and historic frigid temperatures washed over the Lone Star State. According to the National Weather Service (NWS) in Houston, the city received its first Wind Chill Warning on record during this storm. NWS Warning Coordination Meteorologist Alex Lamers also noted that Austin, Texas, experienced its greatest two-day snowfall of 6.4 inches in 70 years on Feb. 14 and 15. The Washington Post reported Dallas experienced its second-longest streak of temperatures below or at freezing in history.
“This was unlike anything we’ve seen,” said Nicholas Cook, Deer Park, Texas, Surface Water Treatment Plant supervisor. “In south Texas, it doesn’t get below freezing for multiple days. When we have a freeze, we’re used to eight to 10 hours and then it warms up and it may repeat again the next night.”
Records like those seen in Texas were experienced in Oklahoma City where the city experienced not only its second-lowest temperature on record (-14ºF) but also its longest streak below 20ºF, according to Lamers and NWS reports. Further north, Chicago experienced its longest stretch with at least 10 inches of snow on the ground since 2001.
The effects of this storm across the midwest — while precedented for northern cities and states — left prepared utilities feeling unprepared.
With record snowfall levels and temperatures streaking below freezing through much of Texas, things turned dire over Valentine’s Day weekend. The electrical grid was stretched to its limits and the Electric Reliability Council of Texas (ERCOT) began to shed power, resulting in blackouts across the state. As millions of Texans went without power to heat their homes in the freezing temperatures, water utilities began to recognize they too were at risk.
To Drip or Not to Drip
As with any major storm anticipated by utilities, resiliency plans and strategies were discussed and put into place, much like the lead up to Hurricane Harvey in 2017. At the core of these plans was a focus on maintaining power at water and wastewater plants, particularly with diesel fuel generators. However, protecting equipment from the cold was also a major consideration.
“Our typical preparation was making sure that we had fuel,” Cook said, “[and] on all of our sensors, we put heat lamps and boxes around the pressure transducers and stuff like that. And that was the majority of what we did.”
Cook said the Deer Park community kept faucets turned on for a steady drip as well because pipes and systems in his community are not winterized. After a few days of doing so, Cook and his team recognized dripping faucets were contributing to a new problem: waning water supply.
“On Tuesday at 12 o’clock, we started losing our elevated towers and between noon and 4:30, our elevated tower dropped from 135 feet down to 60 feet,” Cook said, “so we were no longer storing water. That was just in the standpipe, and that was just three hours.”
Cook’s facility is a surface water treatment plant that uses three water wells in times of emergency, and the plant is rated to handle 8 million gallons per day (mgd). But with faucets dripping, that flow was exceeded.
“One of the guys from our engineering department did the math, and estimated that based on our number of connections, if everybody was flowing a minimal flow, that we would have been using approximately 12.5 mgd,” Cook said.
South of Houston in Pearland, Texas, Public Works Director Clarence Wittwer described a similar approach. He noted that while the public felt the storm most directly for five days, he and his workers felt it for 10 days because of the handful of days spent preparing for Winter Storm Uri before it reached the area.
Similar to Cook, initial messaging considerations for the city of Pearland included asking residents to drip their water faucets; however, Wittwer and other team members caught the message before it was transmitted to ensure that portion was omitted. He said previous experience with freezing temperatures in Texas as a utility manager gave him the insights to ensure it was excluded.
Despite that change, when Wittwer witnessed drops in flow from the two massive drinking water interconnects — 48 inches and 96 inches — with the city of Houston, he knew maintaining system pressure and water for his community would be a considerable challenge.
“A little bit more than 50% of our water comes from those sources and you think, ‘That’s like the ultimate big box on resiliency! I’ve got two massive interconnects!’” Wittwer said. “Well what happens if the neighbor where you get the majority of your water from goes down? That’s what happened here.”
Diesel, Electricity & the Freeze
As the storm continued, demand for electricity to heat homes increased beyond the expectations of electricity providers. As a result, power plants shed power and initiated blackouts, which initially were intended to only be rolling blackouts. However, the demand resulted in long periods of lost power for millions of Texans across the state. Those millions of Texans also included plants like Cook’s and Wittwer’s.
“It was probably 36 hours the first time and then between 12 and 24 hours the second time that we lost power,” Cook said, adding the diesel generator at the water treatment plant was large enough to run all of the plant’s processes. “We did have to get an emergency load of diesel delivered.”
Cook said he contacted the emergency fuel supplier and was put on a priority list to receive diesel before other clients of the fueling station, but running diesel generators in freezing temperatures presents its own challenges. The fuel will gel if an additive is not mixed in, and that gelling can create issues for the generators. This is a problem that Pearland ran into because demand for that additive virtually does not exist in Southern Texas.
Recovery
By Feb. 19 and Feb. 20, both Pearland and Deer Park had begun or entered a state of recovery. Power had returned, for the most part, and water was restored, albeit with boil water notices.
Cook said one of the first orders of business was collecting and running water samples to determine how safe the water was for drinking. Lab personnel was even called into work over the weekend.
“Normally we don’t do that, but everybody was trying to get off the boil water notice as quickly as possible,” Cook said, noting the distribution team has been working to detect and repair leaks throughout the system. “We had lots of calls over two days. They turned off over a thousand connections where homeowners were calling saying, ‘Hey, we’ve got leaks.’”
By driving around town, the bigger leaks were easy to detect. In one case, water was flowing down a sidewalk, and in another, an irrigation backflow preventer was clearly broken. He said loss of flow from those leaks and others were contributors to the drop in water tower levels he noticed in the middle of the storm. However, because the drop was so significant and correlated to the same timeline as a neighboring utility, it indicated the faucet dripping was likely the bigger water loss problem.
To address leaks, Cook said Deer Park will be employing in-line pressure gauges and sensors to better understand the stresses and weaknesses in the system. The city had already begun exploring options before the storm as part of an asset management program and is continuing that pursuit.
On that same note, Wittwer said Pearland had recovered by the weekend after the event and has continued recovery efforts to find any leaks and to address after-action reports. He said one of the larger considerations is redesigning generator capacity for future projects to ensure greater resilience for any current, new and future design work. He also said the city would be looking at enclosures or other means to keep generators insulated during future cold weather events.
The one thing Wittwer said was comforting through the whole experience was the human connection. People helped out other people. Utility managers helped other utility managers. The sense of community, he said, has been a beacon of light in the recovery process.
“That was a big silver lining. To see how the people could work together when they wanted to and put business and political relationships aside and just help each other,” Wittwer said.