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Going green to save green
Purple pipe could slash water & wastewater costs
WATER1 6-01-09
HIME ROMERO/The Bulletin Manteca residents in new neighborhoods could one day water their lawns with recycled wastewater to reduce both their wastewater and water bills.
Managing editor of the
Manteca (Calif.) Bulletin
Every time you flush the toilet you’re flushing money down the drain.
Not only is the three gallons or so of drinking water expensive but making waste water clean enough to meet ever tightening state standards before it is discharged to the San Joaquin River is actually more expensive.
It is one reason why Manteca Mayor Willie Weatherford wants to see that water put to use in the city to avoid future expensive upgrades for releasing treated wastewater back to the San Joaquin River as well as reduce the use of expensive – and scarce - treated drinking water to irrigate lawns.
The way to accomplish that goal is to require new developments to have dual water systems – municipal water for domestic and back yard use and purple pipe water for front yard landscaping as well as landscaping in retail and industrial projects.
Purple pipe is used to convey treated wastewater that is considered perfect for irrigating landscaping and many crops due to its high nitrogen level and over components that help stimulate healthy vegetation growth but also creates problems when it is mixed with river water.
“Sewer bills are based on domestic water use and the biggest use of water for homes is landscaping,” Weatherford said.
Reducing the amount of domestic drinking water used for landscaping extends the supply of water to serve more people. And switching to land disposal for treated wastewater allows the city to avoid ever tightening standards for river releases. Manteca is currently wrapping up a $50 million-plus wastewater treatment plant of which a large chunk was spent for retrofitting to meet new river discharge standards. In addition, Manteca is investing more than $40 million in the surface wastewater treatment plant. Purple pipe deployment of treated wastewater would stretch the effective capacity and of the city’s two largest investments significantly.
The mayor’s route to making Manteca green to save it green as in money is slightly different than some of his council colleagues. Councilman Vince Hernandez has long championed the use of alternative fuel-powered vehicles wherever possible to avoid reliance on foreign oil as well as to battle air pollution.
In the end, both routes get Manteca to the same point which is saving money.
There are already purple pipes in place to ferry irrigation water to the Big League Dreams sports complex and Retail Stadium Center once the city submits a permit request to the Central Valley Regional Water Quality Control Board to start using treated wastewater for that purpose. Currently, some of the city’s treated wastewater is used to irrigate alfalfa and corn for use as silage by leasing some of its land to a farmer.
The purple pipe idea for residential projects may be advanced first by the private sector. A Bay Area firm is working on plans for a large subdivision in southwest Manteca that would include 200 acres of wetlands irrigated by treated wastewater plus possibly purple pipe for front yard landscaping of the homes that are built.
Manteca – along with Lathrop and Tracy – is already getting surface water treated at a plant completely powered by solar energy thanks to the South San Joaquin Irrigation District. That has reduced power costs to run the plant by 15 percent.
Manteca is exploring the use of wind turbine and solar panels to power part at the wastewater treatment plant where the annual power bill is $1.1 million.
Actually, Manteca started going green more than 15 years ago with the idea of saving money first and helping the environment as a close second.
The switch to a separate collection system that diverts yard waste to a compost company and recyclables to another firm has helped keep garbage bills steady by avoiding burying yard waste and recyclables in expensive landfills.
Nearly 10 years ago, the city had an energy audit done with a firm making upgrades that came from part of the money the city was saving. It was what prompted Manteca to become one of the first cities in the Northern San Joaquin Valley to switch to LED lights in traffic signals. They also switched to more efficient pumps for wells and took over the PG&E streetlight system with the goal to save money by reducing energy use. The PG&E purchase also allowed it to improve service as well as significantly reduce costs.

To contact Dennis Wyatt, e-mail