75 Years: TCPUD sewer system keeps North Shore healthy
August 15, 2013
EDITOR’S NOTE: In December, the Tahoe City Public Utility District celebrates its 75th anniversary. To honor the milestone, the district and Sierra Sun have partnered on a multi-part story series that will run periodically through Labor Day weekend. This is the fifth installment. Read parts one, two, three and four here, here, here and here, respectively.
TAHOE CITY, Calif. — Centuries ago, humans used pits, trenches and rivers to hide or take away the body's odiferous wastes. According to Jon C. Schladweiler, historian with the Arizona Water and Pollution Control Association, as early as 3200 BC, manmade sewers moved effluent into percolation fields or along street drains into waterways.
In Crete there were terra cotta lines; in Egypt there were pipes of copper.
People didn't build precursors to today's complete modern systems until the 19th century. On his website sewerhistory.org, Schladweiler credits Hamburg, Germany, with the first complete new sewerage. Tidal waters flushed the main lines once a week, and pipes were vented through roof drains of connected buildings.
North Tahoe had its first chance at a full-blown system between 1963 and 1974 when the Tahoe City Public Utility District began to install a sewer network between D.L. Bliss State Park and Dollar Hill. Lake Tahoe had been discovered, and new subdivisions were proliferating. Scientists worried that seepage from septic tanks and settling ponds would harm the lake.
The sewer collection system installed between 1963 and 1974 was designed at a time when the amount of development that would occur in the basin was unknown. The system ended up being designed for ultimate buildout, numbers that will never be seen in the basin. This overdesign of the system would turn out to be an environmental benefit.
In the same time period, the TCPUD built a treatment plant in Tahoe City and pumped the wastewater uphill to a site that would allow fluids to drain naturally through soil and rock to the Truckee River.
The site was an old cinder cone of fractured volcanic bedrock. The cinder cone arrangement was temporary, satisfying rules outlined in the new Porter-Cologne Water Quality Control Act.
In 1969 California legislators ratified the Act to regulate the discharge of waste into ground and surface waters. The act required all sewage to be exported from the Tahoe Basin.
In 1972, the Tahoe-Truckee Sanitation Agency was formed to build a conveyance line and treatment plant that would comply with the act's requirements to remove all effluent from the North and West shores as well as Alpine Meadows, Squaw Valley and Truckee.
In the final design, the effluent would be transported from Tahoe City by an interceptor pipeline along the Truckee River to a state-of-the-art reclamation plant in Martis Valley.
In 1978, the $32 million system was ready for service. Ron McIntyre, a longtime director of both the TTSA and the TCPUD, recalled that the final interceptor pipe inspection was done by T-TSA's chief inspector, Pete Meredith, who traveled for 17 miles through the 30-inch- to 42-inch-diameter pipeline lying on his back on a skateboard-like apparatus he designed and built himself.
Upon the system's first flows, Tahoe City held a party.
For the TCPUD sewer collection system and its ratepayers, it is lucky the PUD pipes and pumps were sized for a greater population, because the capacity has some important benefits, according to Tony Laliotis, the TCPUD's director of utilities.
"The overdesigned system turned out to be a huge positive," he said. "The excess size and length of the gravity mains contributes to a large storage capacity."
In an emergency, more room for storage means fewer chances for overflows.
A bulk of the PUD sewer resources go to cleaning and maintaining its lines. Some of the biggest problems are powerful tree roots that sometimes enter and block the pipes.
Earth movement from freeze/thaw cycles or earthquake tremors can fracture the pipes. Problems are detected with a closed-circuit TV camera that drives through the lines on wheels.
Unlike the T-TSA inspector of 1978, who called out his findings to an assistant standing above ground with a notebook, the camera conveys images to a computer inside a van, where an operator scans the spooky movie for aberrations.
Each year, the PUD inspects 20 percent of the lines, which means that every five years, they've examined the entire system.
Every year, half of the system is completely cleaned when a 25-foot-long PUD Vactor truck blasts 80 gallons of water per minute through the pipes at 2,500 psi.
"It's like a home pressure washer on steroids," Laliotis said.
With 130 miles of pipe and 22 pump stations, the TCPUD sends an average one million gallons of sewage per day to the T-TSA plant. Peak summer loads surpass 1.5 million gallons a day.
In today's sewer systems, there are still pits, trenches and river channels, but thanks to new technology, as well as to collective brainpower and financing, wastewater is rarely a threat.
The TCPUD collection system and its T-TSA partner pipeline and reclamation plant, continue to provide with a system that Ron McIntyre calls "an elegant design."
— Laura Read is a freelance writer and a 22-year resident of North Lake Tahoe.