OWASA: Wa­ter main break com­pli­cated by sys­tem’s age, com­plex­ity

The Herald Sun - - Front Page - BY TAMMY GRUBB tgrubb@her­ald­sun.com

It’s not clear why a crit­i­cal Or­ange Wa­ter and Sewer Au­thor­ity pipe broke Mon­day on Jones Ferry Road, but the util­ity’s board learned Thurs­day how dif­fi­cult it was to stop the 9.4 mil­lion-gal­lon leak.

It could take about a month for an in­de­pen­dent re­view of the cause and the re­sponse to the emer­gency, said Mary Darr, OWASA di­rec­tor of en­gi­neer­ing and plan­ning.

They are “very sorry” for the bro­ken pipe and how it af­fected the com­mu­nity, Ex­ec­u­tive Di­rec­tor Ed Ker­win said dur­ing a meet­ing Thurs­day of the OWASA Board of Di­rec­tors.

“While it is not pos­si­ble to pre­dict all wa­ter main breaks, we are do­ing and we’ll do more in the fu­ture to min­i­mize the im­pact and risk of such fail­ures,” Ker­win said.

“Our team is cer­tainly com­mit­ted to earn back the trust and con­fi­dence of this com­mu­nity in the ser­vices we pro­vide,” he said. “We know how es­sen­tial they are, and we know we have a lot of work to do to earn that trust and con­fi­dence back.”

Se­cu­rity cam­era footage showed the 16-inch pipe broke

around 6 a.m. Mon­day in front of OWASA’s build­ing, spew­ing wa­ter down the hill and fill­ing Jones Ferry Road. Em­ploy­ees no­ticed it when they ar­rived for work about 15 min­utes later, of­fi­cials said.

The break left more than 80,000 cus­tomers in the Chapel Hill-Carrboro area with lim­ited wa­ter and a boil-wa­ter ad­vi­sory for over 24 hours. It also forced UNC and UNC Health Care to can­cel classes, di­vert emer­gency calls and post­pone elec­tive surg­eries. The Chapel Hill-Carrboro City Schools sent stu­dents home for two days.

BRO­KEN AND COR­RODED

Af­ter eight hours, crews stopped the leak and found a big hole at one end of the 77-year-old cast-iron pipe, said Todd Tay­lor, OWASA gen­eral man­ager of op­er­a­tions. A long crack ran down the side, and a cam­era in­spec­tion re­vealed “quite a bit of cor­ro­sion” around an older tap in the pipe, he said.

The pipe had an ex­pected lifes­pan of 80 to 100 years, Darr said.

The util­ity, which nor­mally keeps 6.4 mil­lion gal­lons in stor­age, lost that and more over the next 18 hours, be­cause the bro­ken pipe drained four wa­ter tow­ers, Tay­lor said. The drain­ing wa­ter pushed back through the plant on its way through the bro­ken pipe.

Cus­tomers were asked to cut their wa­ter use by roughly 25 per­cent, Tay­lor said, and Chatham, Hills­bor­ough and Durham piped in an­other 3.6 mil­lion gal­lons of wa­ter. The treat­ment plant’s un­der­ground “clear­well” tank also helped keep wa­ter flow­ing, he said.

“Dur­ing this whole event, we were pump­ing a tremen­dous amount of wa­ter out into the sys­tem just to keep up with the de­mand of cus­tomers and the leak that was go­ing on at the time,” Tay­lor said.

MORE PROB­LEMS UN­COV­ERED

But the search for the leak was stymied by the rush of wa­ter over the hill, which ob­scured the shut­off valves. Crews went far­ther down the line to turn off other valves, but that did not stop the leak, Tay­lor said.

The next step was rerout­ing the wa­ter away from valves near the break.

“Plan B was also in­ef­fec­tive,” Tay­lor said. “What we found out was some of them were in­op­er­a­ble, some of them were bro­ken, some we couldn’t lo­cate very well, and this plan also did not work as far as iso­lat­ing the break.”

They moved far­ther from the plant, fi­nally shut­ting off the wa­ter around 2 p.m. Mon­day. A pri­vate con­trac­tor was hired to co­or­di­nate the re­pair while OWASA searched for the leak to save time.

The Mof­fat Pipe crew dug a hole 12 feet to 14 feet deep and re­moved a storm drain to reach the pipe, which lay ad­ja­cent to two other large pipes. Only about 99 per­cent of the main leak was iso­lated, Tay­lor noted.

The leak and stress from the re­pair caused other pipes to break in Carrboro, he said, but the stor­age tanks reached 6.9 mil­lion gal­lons by mid­night Mon­day. Crews were still clean­ing up the mess Thurs­day evening on Jones Ferry Road.

The boil-wa­ter ad­vi­sory was lifted at 4 p.m. Tues­day, af­ter all 43 wa­ter sam­ples taken from across the sys­tem tested clear, Tay­lor said. They took 25 more sam­ples Tues­day morn­ing as a backup, he said.

Crews worked through the day Wed­nes­day to com­plete the re­pair and re­place soggy soil with fresh, Darr said.

Among other con­cerns, OWASA board mem­bers wanted to know more about the faulty valves. Tay­lor said the valves should be tested once ev­ery five years – 400 valves ev­ery three months. He did not know the last time the Jones Ferry Road valves were tested.

RE­PLAC­ING PRI­OR­ITY LINES

The break “def­i­nitely is go­ing to in­flu­ence” how OWASA pri­or­i­tizes its wa­ter mains, Darr said. A new model for find­ing high-risk and high-con­se­quence pipes is al­ready un­der­way, she said. They also will ex­am­ine how to iso­late prob­lems in big­ger pipes more quickly.

OWASA’s com­pli­cated, ag­ing net­work of pipes and valves has been in­stalled over the past 70plus years as the com­mu­nity and the needs have grown, Darr said. About 20 per­cent of OWASA’s 380 miles of pipes are at least 40 years old; the av­er­age age is 31, Ker­win said last year.

Darr said quite a few large wa­ter lines need re­plac­ing, and high-pri­or­ity projects are be­ing added to the long-term con­struc­tion bud­get.

OWASA spends roughly half of its $40 mil­lion bud­get on equip­ment and build­ings. This year’s bud­get funds about 60 projects, in­clud­ing $5.5 mil­lion for wa­ter main up­grades – part of a fiveyear, $24 mil­lion plan to re­place 16 miles of pipe.

OWASA’s rev­enues come largely from wa­ter and sewer fees.

Mon­day’s break was the sec­ond time in less than two years that a bro­ken pipe dis­rupted the util­ity’s wa­ter ser­vice. Darr noted there may be some sim­i­lar­i­ties be­tween Mon­day’s break and the one in Fe­bru­ary 2017.

That wa­ter main break shut off ser­vice to res­i­den­tial and busi­ness cus­tomers for more than 24 hours. An in­de­pen­dent re­port blamed hu­man and sys­tem er­rors for that in­ci­dent, which started with a flu­o­ride over­feed at the Jones Ferry Road wa­ter plant.

In that case, the 44year-old pipe was ly­ing 3 feet un­der­ground and less than a foot above a san­i­tary sewer pipe. Ex­ter­nal force and fluc­tu­at­ing wa­ter pres­sure was blamed for bend­ing the pipe, caus­ing it to break.

JU­LIA WALL jwall@newob­server.com

Em­ploy­ees of the Or­ange Wa­ter and Sewer Au­thor­ity work at the in­ter­sec­tion of West Main Street and Greens­boro Street in Carrboro on Mon­day, af­ter a ma­jor wa­ter main break oc­curred out­side of OWASA’s Jones Ferry Road wa­ter treat­ment plant.

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