Water Utility Rebuilds System After Disaster

Rapid response and cooperation with neighboring utilities helped Napa quickly restore water service after a major earthquake.
Water Utility Rebuilds System After Disaster
Napa Water Division General Manager Joy Eldredge, on the Third Street bridge over the Napa River.

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The magnitude 6.0 South Napa earthquake struck Northern California in 2014, killing one person, injuring 200, destabilizing hundreds of buildings, buckling pavement, shearing water pipes and damaging other critical water infrastructure. Despite the devastation, the City of Napa Water Division quickly rolled into action with the assistance of neighboring utilities to stabilize the system and restore services — all within a week.

“It’s an interesting town,” says Water Division General Manager Joy Eldredge, who has been with the utility since 2006. “It’s the largest community in Napa Valley and is only an hour’s drive from San Francisco, yet it’s surrounded by vineyards and has a rural feel.”

The city’s water system harkens back to 1883 and now incorporates 370 miles of pipe, nine pump stations, 12 storage tanks and three water treatment plants.

The water delivery system consists of pipes ranging from 4 inches in diameter up to 42 inches for the largest transmission mains. They’re made of a variety of materials, including welded steel, cast iron, ductile iron, asbestos cement, reinforced concrete pipe and newer PVC. The oldest parts of the system are roughly 70 years old.

The city derives its water from three sources, and also purchases recycled water from the Napa Sanitation District, an independent special district that provides wastewater services to the city and other customers.

An emphasis on improvement

Most of Napa’s new development involves infill housing and subdivisions, so water system work tends to favor upsizing and improvement. In 2012, the utility replaced almost 7,500 feet of transmission main with 24-inch PVC. In 2013, the utility employed horizontal directional drilling to replace and upsize a number of under-highway mains to improve water circulation.

Although the effort is in its early stages, water system mapping is being gradually converted from AutoCAD using Esri ArcGIS as part of the city’s asset management plan.

System maintenance represents a high priority. Although crew members use acoustic leak detectors to pinpoint water loss, leaks are usually easy to spot.

“The pipes are buried between 3 and 5 feet belowground, the minimum coverage required to protect them,” says Eldredge. “At that depth and with dry soil, if there’s a leak, someone will report it quickly — either staff or citizens.”

Distribution system crews handle most pipe repairs. They’re adept with anything from clamps, transmission couplings and sleeves to welding in larger sections of pipe to replace mains damaged by lateral fissures and splits.

The earthquake hits

Those skills proved valuable two years earlier when the earthquake turned the water system into a temporary sieve. The quake hit town on Sunday, Aug. 24, 2014, at 3:20 a.m.

“The epicenter of the quake was out of town in American Canyon,” says Eldredge. “But the earthquake radiated and hit some geological formations so that our community was hardest hit. It came up in the west side of town, opening up streets and creating two new faults.”

Eldredge arrived at utility headquarters at about 6:45 a.m. Electrical service had been interrupted and she required a flashlight to hunt through the darkness.

“Our bookshelves were intact, but every book had been thrown on the floor,” she says. “Somewhere on the floor was the binder for our emergency plan — although most of our planning was for floods, which occur every five to seven years.”

Computers were removed from the office and set up at the designated emergency operations center at the utility’s corporate yard. Cellular and landlines were intact, although incoming calls sometimes overwhelmed city phone circuits.

Quick inspection by utility crews revealed that all dams, water treatment facilities and transmission mains were operational.

Ramping up pressure

To avoid water contamination, the treatment plants were ramped up from 18 to 32 mgd to feed the leaks and maintain positive pressure.

In some areas where the SCADA system was providing no feedback due to electrical outages, crews also put boots to the ground to investigate. Crews found that the roof of the city’s million-gallon Browns Valley water storage tank had been damaged by the shock, which had created 6-foot waves inside the tank.

“The roof was made of corrugated metal and redwood support beams,” says Eldredge. “A wooden splinter became jammed in a valve, which was stuck in the open position, and the tank drained into the system in just a few hours.”

Crews were also dispatched to provide a generator for one pumping station affected by the power outage.

“We wanted to be sure that a second pumping station could take over if the generator failed,” says Eldredge. “We quickly outfitted it with variable-frequency drives so that it could effectively feed the zone if the first one failed.”

Leak reports were being handled through a dedicated phone line. In a typical year, the utility experiences between 80 and 110 leaks. By 9 a.m. on Sunday, 120 had been reported.

“The phone was ringing off the hook,” says Eldredge. “We were putting leak reports onto a spreadsheet and trying to get street addresses because in some cases we were getting multiple reports of the same leak — the corner of Cypress and Mannering might be reported as two distinct leaks. We had everything plotted on a whiteboard, but realized that we needed to be closer to the action and sent staff into the field to determine how many breaks we were dealing with.”

For much of Sunday, the utility prepared for the arrival of crews from the California Water/Wastewater Agency Response Network (CalWARN) and other mutual aid utilities with which Napa had agreements. The utility quickly established 12-hour shifts for crews and ordered fuel, replacement parts, repair materials and backfill.

The cavalry arrives

“The relief crews came through the gate like the cavalry on Monday morning,” Eldredge says. “By then we had determined that we were dealing with 90 actual leaks. Napa crews wanted to get into the trenches and work, but we found out they were much more effective as management because they were familiar with the system and knew where to find valves, for example.”

The utility christened eight crews who went into production mode. Mutual aid crews flushed the system and provided traffic control and prep work, while CalWARN crews excavated and fixed leaks. Napa crews supervised, delivered replacement parts and took water samples. Private contractors were assigned to backfill the excavations.

The rigid cast iron pipes installed in the 1940s experienced the most significant breakage.

“We were able to fix a lot of leaks with clamps, but a few were full circumferential shears that required replacing entire sections of pipe,” Eldredge says.

With the large number of water samples collected for testing throughout reconstruction, the crowded incubator began to overheat.

“Instead of crowding more vials into the incubator, we switched to something like an ice cube tray with smaller samples, so that we could test more samples faster,” Eldredge says.

Repaired by Labor Day

Even as leaks were being fixed, new leaks began to surface. With the participation of all the crews, however, 120 leaks were repaired in a single week, allowing relief workers to go home on Friday and allowing exhausted Napa crews to enjoy at least two days of the long Labor Day weekend.

“We experienced some aftershocks, and for the next six months we experienced another 120 leaks, most of them in the same area that was hardest hit,” Eldredge says. “Our crews worked a lot of overtime right through Thanksgiving.”

While the transmission mains originally appeared unscathed, the asbestos cement pipes developed major leaks in November and December of that year.

“Most of these occurred at the collar where two sticks come together,” Eldredge says. “When the ground shifted and the pipes moved, the rubber gasket rolled out. Once that happened, water pressure eroded the lips of the pipes.”

The effects of the earthquake continued to be felt in 2015. For example, in one of the city’s low-pressure zones, a break in a 20-inch transmission main precipitated six other breaks in subsequent hours on mains that were likely weakened by the quake.

Today, the utility is playing catch-up on some of the maintenance tasks that were necessarily delayed by the massive repair effort.

“We’re probably doubling up on hydrant flushing this year alone, using two crews instead of one,” Eldredge says. “We’re now seeing a more normal leak pattern and we’ve achieved an overall system water loss of less than 5 percent. With the diligence of our crews, we have a very tight system.”


A picture is worth a thousand ... dollars?

For a water utility dealing with the aftermath of an earthquake, taking photographs might be the last thing on someone’s mind. For City of Napa Water Division General Manager Joy Eldredge, however, photography proved to be an invaluable tool following the South Napa earthquake of August 2014.

“We were advised to take photos of leak sites, leak damage and repairs to help create a record of all work done in order to receive compensation from FEMA following declaration of a disaster,” Eldredge says. “You need to document, document, document everything you’ve done in order to get maximum reimbursement.”

The utility carefully accounted for all work performed by its own crews, relief crews and contractors, recording all expenses related to the recovery. While documenting disaster recovery requires significant effort, Eldredge notes that it helped the utility to balance budgets later. Two years following the earthquake, the Napa Water Division continues to receive reimbursement payments that resulted from successful applications to the disaster agency.

“It would be almost impossible to re-create what happened four months after the event, when you present your paperwork to FEMA,” says Eldredge. “Pointing to a patched-up spot on the street isn’t a great way to demonstrate the work you’ve done.”



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