Trenchless Technology

OCT 2018

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48 T R E N C H L E S S T EC H N O LO GY O C TO B E R 2018 C A L L E D T H E "G O S P E L S WA M P S" a century ago for the church-revival gatherings popular there, the southern California city of Fountain Valley later took its name from the area's large artesian wells and unusually shallow groundwater basin that quite literally gushed water fountains aer poking a stick into the ground any deeper than one foot. Heavy water demand and usage has gradually lowered Fountain Valley's high- water table by a few feet since the arrival of pioneer settlers, and yesterday's open irrigation ditches have been long since replaced by a modern water distribution system serving the 56,000 residents of the thriving Orange County commuter suburb located south of Los Angeles. Constructed during the high-growth building boom of the 1960s and 1970s, Fountain Valley 's water pipelines include more than 200 miles of asbestos-cement and coated- steel main pipelines that have largely been trouble-free over the decades — even surviving the region's massive 1994 Northridge earthquake virtually unscathed. However, Fountain Valley 's Water Division is now facing a new threat to their pipelines that even the best water distribution infrastructure cannot avoid: age. " We've been lucky to have experienced very few main pipeline leaks or breaks over the years, but statistical survival curves for our system estimate about half of our deteriorated mains will need replacing in about 10 to 20 years," says Mark Sprague, "ield service manager with the Fountain Valley Water Division. "Our goal was to keep ahead of our aging infrastructure and avoid the scenario of constantly chasing up to 30 pipeline breaks per year with our small staff and budget. That's why we brought in the Echologics team to determine the true condition of our pipeline mains using their ePulse technology." Acoustic-based Condition Assessment Technology "Fountain Valley was facing the same problem as most utilities that are grappling with an aging infrastructure: having insuf"icient data to determine which pipe segments are the best candidates for replacement, and which pipes still have plenty of service life remaining ," says Charlie Fricke, Echologics distribution manager. "Too many utilities are still relying solely on 'desktop' assessment methods based on pipe age, construction type, and leak history to make expensive pipe replacement decisions. However, historical data and statistical analysis doesn't tell you where the truly degraded pipes are located — but ePulse does." ePulse technology uses acoustic wave propagation (AWP) technology to identify sections of pipeline with reduced structural sti›ness, and estimate the average remaining structural strength or wall thickness of a pipeline. Non-invasive and non-intrusive, this technology enables rapid inspection of large areas of a water distribution network without removing the pipelines from service, avoiding service interruptions, pipeline dewatering / cleaning , or costly excavations. The ePulse technology involves inducing low-frequency acoustic pressure waves inside pipelines, measuring the pressure waves using sophisticated acoustic sensors connected externally to the pipe or appurtenances, then analyzing the acoustic data to determine pipe condition. The pressure waves cause the pipe wall to "flex" on a microscopic level, a›ecting the speed of the pressure wave detected by the acoustic sensors. Thicker pipe walls are resistant to this pipe flexing , causing the acoustic pressure wave to travel faster within pipes in good condition. In contrast, slower pressure waves indicate pipe wall degradation and internal corrosion. Using the captured ePulse acoustic data, Echologics field engineers apply advanced algorithms to calculate the average minimum wall thickness of the measured pipe segment without ever entering the pipe itself. Leak Detection Benefits "The majority of our pipelines are 6-in. and 8-in. diameter asbestos-cement pipe, but even our larger 12-in. and 16- in. diameter steel pipe transmission mains are still too small for some other condition assessment technologies that require inserting an inspection device inside the pipeline — making ePulse the best choice for us," says Sprague. " When we learned that Echologics technology was chosen for assessing and monitoring the huge water mains running down the middle of the famous Las Vegas "Strip," we "igured a solution that works for a critical water distribution system serving millions of visitors every year would also work for us." Engaged in the third year of a "ive- year condition assessment project with Condition Assessment in Fountain Valley, California Longer Life from Older AC Pipe By David Stewart Jones

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