aqua-pipe in Jersey City

Jersey City Turns to Trenchless for Water Main Rehab

aqua-pipe in Jersey CityWith its population of approximately 262,000 people, Jersey City is the second largest city in the state of New Jersey, and has the fastest population increase — 5.9 percent — of any municipality in New Jersey since 2010. Like many other American cities, Jersey City is also facing the challenges of aging water mains.

Newark Avenue is a thoroughfare of Jersey City. From the intersection of Summit Avenue to James Street, Newark Avenue required much needed work on all of its underground infrastructures on that section of approximately 4,000 ft. Inside that section is Indian Square, also known as “Little India.” This portion of Newark Avenue is vibrant with grocery stores, electronics vendors, video stores, clothing stores and restaurants and is one of the busier pedestrian areas of this part of the city, often stopping traffic for hours.

Newark Avenue and Indian Square were the scene of a lot of work in the summer of 2015. First, Newark Avenue was trenched open on 4,000 lf for the replacement of the sewer line. More trenching was done to perform much needed work on gas and electrical lines. By September, the residents and business owners were feeling the social and economic impact from the disturbance related to the construction, and the renewal of the water mains was still to be dealt with.

Newark Avenue has a 6-in. water main running from James Avenue on 3,400 lf, then the diameter goes up to 8 in. and the water main continues 600 lf up to the intersection of Summit Avenue. This water main, believed to be from the early 1900s, has shown events of breaks.

The work consisted of structurally lining 3,000 lf of 6-in. pipe providing water to 52 residences.

The work consisted of structurally lining 3,000 lf of 6-in. pipe providing water to 52 residences.

Trenchless Option

Rajiv Prakash, P.E., staff engineer at Jersey City Municipal Utilities Authority, knew that the replacement of the water main would have required digging another trench. Considering the previous inconveniences to the residents and business owners of Newark Avenue and the presence of other utilities adjacent to the water main, a traditional replacement by open-trench was not an option. He considered trenchless options for the water main renewal.
Jersey City has been a long-time user of cement mortar lining and is very familiar with this form of water main rehabilitation. However, from recent water main breaks on Newark Avenue, Prakash had considered a structural form of water main rehabilitation.

In October 2014, Prakash along with Hatch, Mott MacDonald vice president Earl Schneider, P.E., visited a jobsite in Woodbridge, N.J. The jobsite was the stage for the trenchless structural lining of water main using the Aqua-Pipe technology from Sanexen. The work consisted of structurally lining 3,000 lf of 6-in. pipe providing water to 52 residences. “This technology has great potential and we have potential applications in mind in the near future,” said Schneider when he left that site tour.

Prakash recalled that visit and he knew that Aqua-Pipe would be the answer for the Newark Avenue water main rehabilitation.

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Prakash, Schneider and Sanexen Water met to discuss the feasibility of Aqua-Pipe. The water main was running in a straight line with no evidence of severe bends. The street crossing and associated “T” connections were clearly identified; valves, fire hydrants and water services (connections) were clearly located. The liner insertion pits, 6 ft by 9 ft in size, were to be located at the “T” connections from incoming water mains from side streets, at fire hydrant 6-in. branches and at fire protection services (4-in. connections). Approximately 70 service connections were to be re-opened from inside the pipe using robotics. Newark Avenue was an excellent candidate for structural lining with Aqua-Pipe. Schneider put members of his Hatch, Mott and MacDonald team to prepare technical specifications for the structural lining of the water main.

The rehabilitation of the Newark Avenue water main was planned in two phases; Phase 1 was to cover the structural lining of 2,000 lf of 6- to 8-in. from Summit Avenue to Tonnelle Av (including the Indian Square neighborhood) while Phase 2 was to cover the remaining 2,000 lf of 6-in. water from Tonnelle Avenue to James Avenue. However, a major challenge related to the construction schedule of Phase 1 was thrown on the table.

Phase 1 Challenge

Originally, the construction of Phase 1 was scheduled in October as the repaving of that section of Newark Avenue was planned for early November. Indian Square is home to the largest outdoor Navratri festivities in New Jersey. Navratri is an important festival and it was opening on Oct. 16 on Newark Avenue. With the construction that took place all summer, it had been decided that Newark Avenue was to be totally reconstructed and repaved for the opening of the Navratri festival. It was mid-September when Sanexen Water was faced with that change of schedule.
The general contractor was early at work with the installation of the water by-pass and the excavation of required access pits. Sanexen Water put in extra efforts to mobilize equipment and crews earlier than planned. The water main was cleaned prior to lining. As time was of the essence, two methods of cleaning were used. One is using a combination of high-pressure water and mechanical reamer. This turned out to be slower than usual in this heavily tuberculated water main. To speed up the cleaning process, scrapers were used to aggressively remove the tuberculation from the pipe and restore it to its original diameter.

As a final preparation to installing the CIPP liner, service line plugs were robotically inserted into each residential service connections. The purpose of this operation is to prevent the resin used to cure the liner in the main from travelling up each service, resulting in a plugged service. The resin is used in excess quantity to fill the voids around the services, ensuring there is a tight adhesion and no water can infiltrate behind the cured liner. This preparation was made complicated as many of the 57 total service connections showed damages from the aggressive cleaning operation. Such service connections had to be robotically reshaped in order to make the insertion of the service line plugs possible.

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Once the interior of the main was prepared, the Aqua-Pipe liner was inserted and cured inside the main. From the inside of a refrigerated truck, a liner is injected with resin between its two layers of woven fabric. The liner is pulled from the truck into the access pit and into place inside the water main through rollers.

Once inside the host pipe, the liner was pressurized with hot water. While curing, the polymeric resin was pushed along the host main, creating adherence, filling any void or cracks. The hot water is circulated inside the liner for complete reticulation and then left to cooldown overnight. The next day, the crew performed a camera inspection to ensure the liner was properly installed. Once completed, the liner inside the main was pressure tested and met the requirements under ASTM F1216. In four days, a total of seven liners (five liners of 6-in. diameter and two liners of 8 in.) were successfully installed inside the water main of Newark Avenue.

Following this, service connections were reinstated using robotic equipment to drill through the liner and the service plug. Six services connections, damaged by the aggressive cleaning, had to be dug up for reinstatement.

As final steps, new fittings, hydrants and valves were connected by the general contractor just as if it was a full replacement. It was then chlorinated and tested before being commissioned. Work went on to backfill all access pits and excavation. On Oct. 16, the Navratri Festival opened with a fully restored and newly paved Newark Avenue with an estimated 25,000 visitors on Friday and Saturday.

Prakash was pleased with the completion of Phase 1 in the short schedule and believes that Aqua-Pipe was a good solution. “The location of the water main, the presence of other underground infrastructures, the business and social activities that are part of Newark Avenue, made Aqua-Pipe the perfect solution for a fully structural rehabilitation of the water main,” said Prakash.

The construction of Phase 2 of the structural lining of the Newark Avenue water main was scheduled to begin in early November. When Phase 2 is completed, Jersey City MUA will be the leader in structural lining installation in the state of New Jersey.

Aging of water main is a largely acknowledged concern. For many years, trenchless rehabilitation of water mains consisted of non-structural options and they provided a solution pertinent to problems and issues of the time: corrosion, brown water, etc. Despite previous non-structural lining work, the aging process has now weakened the structural capacities on many of these pipes. Now, Jersey City MUA, like other utilities, is experiencing increasing numbers of breaks and leaks on such aging water mains.

“The trenchless rehabilitation of water mains using a structural liner is an option we are now putting forward when it comes to management of our aging water mains,” said Prakash.

The structural lining of the Newark Avenue water main is a preview of many more similar projects to come in the United States.

Robert Dumais, T.Sc.A., is vice president, Eastern Region, Aqua-Pipe Sanexen Water Inc.
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