Same day return to service
Bitumen lining removal and application of water quality lining in 1960s-era cast iron water pipe in Saint John, New Brunswick
In September 2013, the Tomahawk pipe cleaning system by Envirologics Engineering Inc. played a key role in a successful, same-day return to service, six-inch cast iron water main rehabilitation project in Saint John, New Brunswick. Tomahawk was required to remove the internal corrosion buildup and old bitumen liner to ensure the long-term bond and leak-free performance of the applied spray in place pipe (SIPP) liner.
Trenchless Solutions from Moncton, New Brunswick, was the general contractor and has several years of experience cleaning and lining deteriorated metal water mains. Trenchless Solutions is a certified applicator of the 3M Scotchkote Pipe Renewal Liner 2400 product. 3M representatives were also on site to evaluate Tomahawk’s performance as this was their first exposure to the method.
“The Tomahawk System proved its capability to remove pre-existing, internal, bitumen coating from cast iron water mains. The process left behind a clean, dry pipe that enabled a successful application of 3M Scotchkote Pipe Renewal Liner 2400.”
Shawn Sweeney, 3M Water Infrastructure Solutions
The Saint John project was part of an annual program to renew its water distribution pipe network. The project called for the application of a water quality lining to restore the pipe’s hydraulic capacity, improve water colour and taste, and to prevent future corrosion. During the course of the project, a 435-foot section of pipe was discovered to have an old bitumen liner after initial cleaning. An attempt was made to remove the bitumen but was unsuccessful.
Trenchless Solutions then contracted Envirologics to remove the bitumen from the 435-foot pre-cleaned pipe along with a second 357-foot section. Once on-site, Tomahawk quickly removed the corrosion and bitumen from the 435-foot pipe in 2 ½ hours. The pipe was left in a clean and dry state, ready for lining. The results generated excitement by those watching including a lining crew member who claimed this to be “the cleanest pipe” he had ever seen.
On the following day, the 357-foot section was cleaned by Envirologics in under 3 ½ hours. This pipe had not been precleaned thus requiring both tuberculation and bitumen removal. It was cleaned and lined under “same day return to service” conditions since no service bypass was in place. The water main was taken off line, cleaned, inspected, lined, flushed and reinstated by evening under a “boil water advisory”. The advantages of same day return to service include lower project cost and timing along with a significant reduction in the duration and amount of street level disruption. City of Saint John staff members expressed their approval of several of Tomahawk’s features. The system is closed meaning no internal pipe deposits are exposed to the public and all waste is captured for ease of disposal. The process is a dry cleaning method eliminating non-revenue water consumption and disposal of wet waste. Envirologics’ Tomahawk Scout is an airstream-driven, CCTV camera with an integrated abrasive deflector and was deployed to target-clean remaining patches of bitumen in real time, much to the delight of the viewing audience. This is the only known process to effectively remove bitumen from water mains, eliminating the expense of dig and replace.
“The Tomahawk is an effective trenchless system that quickly removes tuberculation and bitumen lining from cast-iron pipes. The pipe is left clean and dry, ready for lining.”
John Campbell, City of Saint John Engineering
Trenchless Solutions was also pleased with the cleaning results. The pipe was left dry without the need for extensive swabbing. The Scout was again deployedto aerodynamically draw out debris andwater from joints and service connections.The joints and service connections wereleft undamaged and the quality of liningwas superior due in part to how clean anddry the pipe was left.
This project was validation of Tomahawk’scapability to remove tuberculationand bitumen from cast iron watermains in a “same day return to service”environment. Envirologics believes thereis a large market for cost-effective, waterquality, non-structural liners. Cast ironand steel pipes that have been protectedby bitumen liners are often in excellentcondition and do not require a more expensivestructural solution. The ability torehabilitate and return the water main toservice in the same day will only increasethe market opportunity.