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Pioneering Spirit in Colorado Consolidated Mutual Water Company Gets Ahead of the Game with Pipe Bursting By Jim Rush Celebrating its 85 th anniversary in 2011, the Consolidated Mutual Water Company (CMWC) in Lakewood, Colo., is continuing the pioneering spirit of the company founders who banded together to provide water for the growing population in the West. Serving a population base of approximately 85,000 people in the communities of Lakewood, Wheat Ridge and unincorporated portions of Jefferson County, CMWC is in the midst of a pipe replacement program that is saving the community money while increasing water quality and reliability. Beginning in 2010, CMWC began a systematic program to replace aging water pipes using the trenchless replacement technique of pipe bursting. Even though the program has been in place a short time, the results are already evident. CMWC is increasing its pipe replacement program in terms of footage installed per year with less cost and disruption to customers. Other utilities, including the neighboring communities of Denver, Aurora and Golden, have taken notice as well. In fact, CMWC has hosted some 1,000 visits to its jobsites over the past two years to see if the success can be replicated elsewhere. Background As the City of Denver grew in the early 20 th century, so too did its suburbs. To the west of town, water was obtained by drilling deep wells that came with considerable costs. To help allay these costs, residents banded together and formed “mutual water companies” that provided wells, pumps and distribution piping. In 1926, four of these companies — the Oaks Mutual Water Company, the Glen Creighton Mutual Water Company, 22 Water Utility Infrastructure Management November/December 2011
the Wadsworth Mutual Water Company and the North Wadsworth Mutual Water Company — merged to form the Consolidated Mutual Water Company. Through the years, CMWC expanded through additional mergers to its present service area of approximately 27 square miles and 400 miles of distribution. Instead of using the deep wells, which were not considered sustainable, CMWC acquires 70 percent of its water through the City and County and Denver. To help offset the effects of rationing and ensure adequate water supply to sustain growth, CMWC acquired surface water rights and constructed the Maple Grove Reservoir and Treatment Plant, which were completed in 1957. These facilities now provide approximately 30 percent of the water supply. The CMWC piping network comprised mostly cast-iron pipe installed in the 1940s and earlier that was reaching the end of its useful life. The pipe was suffering from corrosion and tuberculation, which resulted in water main breaks and water quality issues. In the past, CMWC had relied on open trench replacement of water mains, which resulted in disruption to residents and businesses in addition to the high cost of surface restoration. Mike Queen, president of CMWC, estimates that open trench replacement cost the utility an average of $112 to $115 per foot. Looking for a Better Way After Queen was invited to view a pipe bursting program in Florida, he was intrigued by the process and initiated a pilot project in Colorado. After evaluating and testing bursting equipment and piping products, CMWC decided to proceed with a pipe bursting program to replace approximately 25,000 linear feet of water mains beginning in April 2010 targeting areas with antiquated and undersized lines. In total, CMWC crews replaced 27,000 linear feet of pipe in 2010. While many cities hire specialty contractors for pipe bursting projects, CMWC elected to use its own crews. “We’ve always done our own pipeline installation, so we’ve always had our own construction crew. And it is the opinion of the Board, and mine too, that if we’re going to own it and maintain it, we might as well install it so that we know what we are getting. We met with the construction crew prior to starting the pipe bursting program and said ‘this is the direction we’re going, we need you on board,’ and everybody bought into it,” Queen said. CMWC purchased a TT Technologies 800G static pull pipe bursting system and McElroy fusion equipment to install DR 18 Fusible C-900 PVC pipe from Underground Solutions. CMWC enlisted the technical Cast iron pipe installed in the 1940s was being replaced to increase system reliability and water quality. Advanced Water Treatment Technology Pipe replacement isn’t the only area of innovation at the Consolidated Mutual Water Company. CMWC recently upgraded its Maple Grove Treatment Plant. The plant upgraded its capacity to 15 mgd (expandable to 18 mgd) and uses GE’s ZeeWeed Ultrafiltration membrane as part of its primary and secondary treatment process. The membrane is a pressure-driven barrier to suspended solids, bacteria, viruses, endotoxins and other pathogens used to produce water with very high purity and low silt density. It can serve as a treatment for surface water, groundwater, and biologically treated municipal effluent (membrane bioreactor and tertiary treatment). It can also serve as a pre-treatment before reverse osmosis and other membrane systems. Plant operator Chuck Conway said that turbidity regulations were the primary driver installing the membranes as the Maple Grove Plant. The plant uses the ZeeWeed 1000 system membrane for primary treatment and 500 system membrane for secondary treatment. A full-scale ZeeWeed treatment facility is comprised of a given number of modular components: modules, cassettes, and trains. A module is the basic building block and the heart of a ZeeWeed system. Each module contains thousands of horizontally strung membrane fibers that have millions of microscopic pores in each strand. Water is filtered by applying a slight vacuum to the end of each fiber which draws the water through the tiny pores and into the fibers themselves. The pores form a physical barrier that allows clean water to pass through while blocking unwanted material such as suspended solids, bacteria, pathogens and certain viruses. Modules are joined together to form a cassette, which is the smallest operable unit of the filtration system. Each cassette can have a variety of module configurations depending on the amount of water that the cassette is required to treat. Multiple cassettes are joined to form what is known as a process train. The train is a production unit containing a number of cassettes immersed in a membrane tank. Multiple process trains form a ZeeWeed treatment plant. Feed water flows into the membrane tanks and treated water is drawn through the membranes during Production by applying a vacuum to the inside of the membrane fibers. The water removed by permeation is replaced with feed water to maintain a constant level in the tank. The particles that are rejected by the membrane pores remain in the process tank and are periodically removed by a process called a Backwash (BW). During a backwash, filtered water is reversed through the membrane fiber to dislodge any particles that may be physically lodged in the membrane fiber. Simultaneously, aeration scours any solids that are attached on the surface of the fibers. To prevent fouling of the ZeeWeed membranes operators are required to perform regular maintenance cleans (MC). Maintenance cleaning begins by draining the membrane tank and soaking the membranes in a cleaning solution for several minutes. The solution is then drained and chemical residues are flushed from the membranes before the system resumes normal operation. November/December 2011 Water Utility Infrastructure Management 23
Page 2 and 3: For more information visit www.uimo
Page 4 and 5: CONTENTS November/december 2011 COV
Page 6 and 7: 36 34 Teaming Up for Water Delivery
Page 8 and 9: CONTRIBUTORS Pamela A. Malone serve
Page 10 and 11: FROM THE PUBLISHER’S DESK CWC and
Page 12 and 13: NEWS WEFTEC 2011 Attracts Strong Cr
Page 14 and 15: NEWS MEETINGS U.S. Conference of Ma
Page 16 and 17: NEWS LEAK DETECTION Wachs Water Ser
Page 18 and 19: W A S H I N G T O N R E P O R T Mob
Page 20: For more information visit www.uimo
Page 25 and 26: Water Utility Infrastructure Manage
Page 27 and 28: Background Utility: Douglasville-Do
Page 29 and 30: screen. The ratio of productive, sc
Page 31 and 32: There are common issues across util
Page 33 and 34: P3 Implementation in Canada Public-
Page 35 and 36: Tampa Bay Water, Veolia Water North
Page 37 and 38: eports. Future reviews, validation
Page 39 and 40: The consequences of failure usually
Page 41 and 42: PROFESSIONAL INDEX Company Website
Page 43 and 44: Uniting the Trenchless World Presen

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