The City of Livonia, Mich., found the way to save its water system and also keep costs under control by selecting pipe that is long-lasting, leak-free and makes it possible for a highly desirable method of installation to be used.
Just a 30-minute drive from Detroit and with a population of almost 100,000, the City provides more than 16 million gals of water daily (mgd) to more than 38,000 residential, commercial and industrial customers through some 400 miles of water main pipe that varies in size from 3 to 36 in. Like many other communities today, it was faced with potentially expensive decisions concerning sections of the water system nearing the end of its useful life. Much of the system grid is well beyond its original 40-year expectation, with some pipes older than 60 years.
For many years, the iron pipes were cracking and coming apart at the joints. System failures due to water main breaks were a growing problem. The ductile iron pipe, from large trunk lines to smaller distribution branches, was also prone to constricted flow due to tuberculation that was caused by the buildup of rust and sedimentary deposits of various salts, such as iron and magnesium precipitates.
The regulating authority for water in Michigan is the Michigan Department of Environmental Quality (MDEQ). Current guidelines indicate that if a municipal water supply is to provide service to customers and for fire protection, the minimum pipe size is 6 in., while maintaining a residual minimum pressure of 20 psi at all points in the system.
Not only was the City of Livonia facing the inability to maintain pressure and flow, there was also the loss of treated water due to the leaks, plus the possibility and risk of contamination due to infiltration of groundwater and other outside materials.
“During the past 20 years, we experienced an increasing number of incident reports of broken water mains that required digging up the streets to do the repairs,” stated Livonia Mayor Jack Kirksey. “At first it was manageable. But during the past five years, the failing sections were reaching a catastrophic stage. Not only were we losing water — a valuable resource — but the cost to our taxpayers was significant. We had to find a way that would solve this problem and also be financially prudent. In other words, find the best system that would last the longest and have the most realistic cost.”
City of Livonia water managers worked with local consulting engineering firm Hubbell, Roth and Clark Inc., Pontiac, Mich., to pinpoint the best way to save the water system. They also turned to the Plastics Pipe Institute (PPI), an educational trade association representing all segments of the plastic piping industry, for information, recommendations and guidance to remedy the problem.
An analysis of the system found that nearly 23,000 ft of deteriorated water main was in need of replacement. The aging pipes were generally 6 to 8 in. in diameter and it was obvious that replacement was warranted to maintain the integrity of the system.
The consulting engineering firm assembled contract documents that were publicly advertised for potential construction contractors to bid. The documents allowed replacing the pipe with a similar iron product or with pipe made from high-density polyethylene (HDPE).
“Both HDPE and iron pipe are industry standards for water main supply and are acceptable to the City of Livonia,” explained Daniel W. Mitchell, P.E., of Hubbell, Roth and Clark. “Although Livonia specifies the use of poly-wrapped, cement-lined, ductile iron, (called DI), pipe for water main use, HDPE pipe has also been allowed in recent years. The reason for this is that the HDPE pipe enables the trenchless method of installation to be used.”
Typically, water main replacement involves excavating equipment to dig up roads and residential lawns. The pipe is then laid out, sections joined together, connections made and the trench backfilled. This method is expensive because of the labor required and also puts residents on the defensive because of the disruption, safety concerns and traffic detours.
The City’s water managers recommended using HDPE pipe because it provided the single solution to the multi-faceted problem of doing the repair. PPI-member company Charter Plastics, Titusville, Pa., HDPE pipe was selected for the replacement and upgrade.
Various methods of construction were considered. A relatively new technology known as “pre-chlorinated pipe bursting” that utilizes HDPE was identified as the most cost-effective through the bidding process. The method of installation made possible by the use of HDPE pipe involves using the old pipe as a pathway and bursting it as the new HDPE pipe is pulled through the failing ductile iron pipe. Only small entrance and exit pits are needed to accomplish the replacement and upgrade, not the extensive trench digging normally required.
Charter Plastics’ PE 3408 Ductile Iron Pipe Size HDPE pipe was used. Its solid wall design and physical characteristics allows pipelines to be relined by using trenchless pipe bursting technology. It meets AWWA requirements for polyethylene pressure pipe and also meets ASTM F714 requirements.
The HDPE pipe was joined by heat fusing the sections together in the field using a McElroy 412 self-contained fusion machine. This method was faster and more efficient to do than welding or clamping iron pipe and it created a single, monolithic pipeline, free of potential leaks even though it was blocks long in some areas. McElroy Mfg., Tulsa, Okla., is also a PPI member company.
“We were putting in a total of more than 27,000 ft, which means a savings of more than $200,000 just for the pipe, not including cost associated with the labor and time that would be needed to handle and install the much heavier iron pipe. The end-result is that we were able to do this without raising the rate for water,” Kirksey said.
Once the process began, it went very quickly. Most homes were reconnected to the system within three to four hours. The project started in April 2008 and finished that October.
Hubbell, Roth & Clark’s Dan Mitchell summarized the initial steps. “The City knew it had a problem, and [Major Kirksey] along with the City Council and others established a budget they felt they could afford to address the problem. The staff was asked to prioritize the worst areas for a capital improvement program that would be within the budget. Once a scope of the project had been identified, the City solicited for engineering services in order to design, prepare bid documents and administer the construction of approximately 27,000 ft of new main — 23,000 ft as replacement main and 4,000 ft of new main for looping purposes.”
After making the decision to replace the failing water system, the City’s concern turned to the destruction of both public and private property usually required when an underground system — water, gas, sewer and conduit — is installed. The City didn’t want residents to face a hardship from ripped up streets and sidewalks.
Because HDPE pipe is somewhat flexible, strong and durable, it provides the ability to horizontally directional drill the pipe in close spaces — just a small hole about 3 ft wide to start each run. From that starting point, the crew was able to snake the pipe through the old ductile iron pipe. This reduced the cost and eliminated the need to open-cut. Plus the pipe has fusion-welded joints for zero leakage, it’s corrosion-resistant for a long life and it meets AWWA standards for potable water applications.
If the traditional open-trench method was used to install the new pipeline, it would have been necessary to set up road barriers or detours, making navigating the streets difficult and dangerous while further upsetting drivers and pedestrians.
According to the PPI executive director Tony Radoszewski, “The popularity of using polyethylene (PE) pipe in municipal water systems has continued to grow. Officials on the state, town, city, county and federal levels find it to be an economical and environmentally-sound solution with proven longevity and reliability to replace aging pipe systems.”
“What Mayor Kirksey and his team did for Livonia is no different than any other leader can do,” Radoszewski observed. “By investigating alternative technologies, a major problem was solved, plus the community and construction workers were protected from unnecessary turmoil and dangers.
“Too often we hear or read about a construction project that was the site of a disaster after a backhoe hits a gas pipeline while digging a trench. Or a trench caves in, burying workers. From 2000 through 2006, there were 271 deaths related to trench work, according to the latest United States Bureau of Labor Statistics.
“Mayors, city managers, public works directors and consulting engineers realize that digging trenches that upend and endanger lives is unnecessary now,” he stated. “The technology and products now exist that permit a more safe, practical and economical way to install a water system.
“We are facing serious challenges when it comes to crumbling underground infrastructure — namely water and sewer pipes — and billions of dollars have been specified for water and sewer infrastructure projects,” he continued. “Decisions about materials used and how repairs or expansions are done are vital to us all. The choices about to be made will have an impact on us now and for generations to come.”
On Feb. 20, a large contingent of mayors met with President Obama, members of his Cabinet and Vice President Biden to discuss cities’ role in implementing the American Recovery and Reinvestment Act (ARRA) and how to get billions of dollars allocated by the stimulus plan flowing to cities.
“Pipe systems made from high-density polyethylene do not rust and are leak-free — the two biggest problems facing water utilities today. Our city’s gas utilities almost exclusively use HDPE pipe for these very reasons,” Radoszewski said. “Furthermore, HDPE pipe systems are ‘green’ in every sense of the word. They are sustainable, use less energy to manufacture and ship, many times they are less expensive than traditional materials like concrete and metal and with superior joints, they are better at protecting natural resources. “
Kirksey had some advice for other mayors: “The use of HDPE pipe is a progressive step that all other cities should consider to reduce costs and disruption of daily life during the project and to improve their water infrastructure with a long-life product.”
Steve Cooper is a freelance writer who frequently reports on the water industry.