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Preparing for next big one

Manteca & Lathrop coordinate flood safety plans

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Preparing for next big one

Manteca Community Emergency Response Team volunteers including Ken Sanders, left, and William Matthews, underwent training in 2011 on the best and quickest way to fill sandbags.

HIME ROMERO/Bulletin file photo


POSTED August 15, 2013 1:50 a.m.

The next time a levee breaks in the Manteca-Lathrop area the response will be even better coordinated than it was during the devastating floods of January 1997.

Elected city leaders in both communities have entered into an agreement with San Joaquin County to interweave flood safety plans and to make sure response time is as quick as possible to evacuate residents. The agreement will make the reclamation districts in the region eligible for state funds to upgrade levees.

Plans have been in place since the 1997 emergency that forced the evacuation of more than 2,000 people south of Manteca and put another 10,000 people in Lathrop and Weston Ranch on stand-by notice of possible evocation.

During the 1997 flood several command centers were established as waters forced emergency crews to retreat to a second location at Nile Garden School and then move to the Powers Avenue fire station. The agreement establishes the Robert Cabral Agricultural Office in Stockton as the command center for coordinating the execution of flood evacuation safety plans.

Officials had to scramble to secure evacuation centers that included schools and the Boys & Girls Club. Plans that are in place and those that are being modified will take the guess work out of evacuation centers and emergency steps needed to protect residents from advancing floodwaters.

Sixteen years ago, state emergency officials were bracing for the worse when levees south of Manteca started failing.

A “boil” – so named for water that bubbles up on the wrong side of a levee meaning water is undermining it – broke on the Stanislaus River levee.

Secondary levees south of Woodward Avenue and those at the Mossdale bend on the San Joaquin River showed signs they were nearing failure.

The disaster scenario was quickly drawn up. Failure of the San Joaquin River levee where new boils seemed to be popping up every hour could send water rushing north to Weston Ranch where it would reach the first homes in that south Stockton neighborhood within seven hours.

The same break could inundate nearly a half of Lathrop.

The assessment of the potential damage from the secondary levee south of Woodward Avenue failure was somewhat better. The Office of Emergency Service envisioned a break sending water rushing toward the Highway 120 Bypass that has been designed for conversion into an emergency levee. Once there, it would pour through the McKinley Avenue undercrossing and spread out threatening the Manteca-Lathrop wastewater treatment plant, a large chuck of the Airport Way corridor and could possibly send two to three inches of water into the Sierra High neighborhood.

The orders went out: Plug the McKinley Avenue undercrossing of the Highway 120 Bypass with tarp covered dirt and do the same for the Louise Avenue undercrossing of Interstate 5 in Lathrop. Caltrans crews also would be ready to close the Lathrop Road undercrossing of I-5 at a moment’s notice.

Meanwhile, Weston Ranch residents were advised to prepare for a possible evacuation. Thousands of families did just that loading up pickup trucks, cars and rental trucks with as much of their personal belongings as possible. For several days, Weston Ranch residents were ready to flee.

It was touch and go for 72 hours before thousands of California Conservation Corps workers teamed up with volunteers to sand bag boils – areas oozing mud on the land side of the land side of levees – were able to gain the upper hand.

It had all started in November and December of late 1996. Mother Nature had dumped a near-record 180 percent of snow-fall on the Stanislaus River’s upper watershed by mid-December. The same was true on other rivers feeding into the San Joaquin including the Stanislaus. New Melones was at 95 percent of capacity since it rarely had an early run-off.

Then a series of storms dubbed “The Pacific Express” slammed Northern California on New Year’s Day dumping an inordinate amount of warm rain.

If a similar scenario were to occur today, more than 500 homes in southwest Manteca near Airport Way and Woodward Avenue would be in danger as would most of Lathrop except River Islands and all of Weston Ranch.

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