When PG&E goes to de-energize all power lines to the entire of City of Manteca for as long as five days when severe wildfire danger in the Sierra foothills warrants it, the move could end up elevating the fire risk in Manteca.
That’s because the wildfire season coincides with the heaviest water use period in Manteca when both treated surface water and well water — both needing electricity to operate — are at their highest demand. City wells no longer are put into use during the winter season as water use plummets.
And while municipal wells are equipped with backup generators the South San Joaquin Surface Water Treatment Plant that supplies the lion’s share of municipal water to Manteca is not.
South San Joaquin Irrigation District General Manager Peter Rietkerk Wednesday noted redundancy for power — which would have cost millions of dollars — was not built into the treatment plant as the cities of Manteca, Lathrop, and Tracy never intended to rely on it as their sole water source.
Once PG&E cuts off power, the plant 15 miles northeast of Manteca near the base of Woodward Reservoir will stop treating water. Rietkerk said the only treated water that would be available is in a storage tank at the treatment plant and — in Manteca’s case — three large storage tanks located on Atherton Drive near Woodward Avenue, on West Yosemite Avenue by the wastewater treatment plant, and Lathrop Road near Union Road.
If power is cut on a high demand day — typically when temperatures are in the high 90s or past the 100-degree mark — the treated water supply available to the three cities could be gone in less than a day.
Manteca would be forced to rely exclusively on municipal wells that have backup generators.
That creates two issues.
The three water tanks help pressurize the municipal water system. All three water tanks are filled directly from lines coming from the SSJID main water transmission line that runs through the northern part of the city to Lathrop where it crosses the San Joaquin River at Mathney Road on its way to Tracy.
Low water pressure may be an inconvenience for residents taking a shower, washing their hands or irrigating lawn but when it comes to water drawn from fire hydrants it can seriously compromise firefighting efforts.
The second issue was underscored during the 1996 Western North America blackout when 2 million people in six western states including Manteca residents lost power during an extraordinary high demand during a sustain period of 105-degree plus days in August of that year. While most of those impacted had power restored in two hours Manteca went without power for close to seven hours.
At the time Manteca only had wells running that were relying on backup generators. People headed outdoors to try to use sprinklers and water hoses to stay cool. Fire personnel at the time were fretting dropping water pressure — that was nearing the point before power was restored — of being so anemic that it would severely hamper firefighting efforts in the event of a structure fire.
The outage was nowhere near the five days PG&E is telling the city to prepare for this wildfire season because they can’t isolate Manteca from other communities in the foothills when they de-energize the transmission lines that slice through the city’s heart. When PG&E cut off power under similar circumstances in mid-October of last year to more than 118,000 customers, electricity in most areas was not restored for two to three days
Manteca Fire Chief Kyle Shipherd Wednesday said it will be a top priority to work with Public Works Director Mark Houghton to see what the limitations are and how taxed the water system would be in terms of available water and pressure critical to combat a fire.
Shipherd is spearheading emergency planning for potential pre-emptive PG&E power cutoffs that — had the utility’s policy been in place two years ago — would have triggered three prolonged forced blackouts based on weather and wildfire conditions.
The city would still be able to run the wastewater treatment plant but all traffic lights and street lights would go dark.
It is highly likely the city may have to suspend all landscape watering during the duration of a PG&E move to de-energize the entire city. Given automatic timers are needed for most grass watering those systems wouldn’t go on.
However for the city to communicate any necessary change in water consumption due to public health and safety concerns would be problematic given the city’s website would be down and use of apps on smartphones and such would be limited as the devices need to be recharged. Television would not work. That would basically leave battery operated radios as the best alternative. It is not likely very many households have battery operated radios.
To contact Dennis Wyatt, email dwyatt@mantecabulletin.com
