管道修复人的圈子

美丽的海滩点缀着新泽西州的海岸线，虽然游客们在海洋边欣赏着美丽的沙子，但它会对构成社区废水收集系统的管道造成严重破坏。当连接三个海岸线社区和污水处理厂的关键力量干线开始出现故障时，大西洋县公用事业管理局 (ACUA) 就面临着棘手的困难。

最初的直径为 30 英寸的焊接钢主力主管用于从文特诺、朗波特和马盖特镇（被称为下海滩的地区）输送废水，安装于 1970 年代中期。它从下海滩地区向北延伸至处理设施。一路上，它穿过一条前市政简易机场巴德菲尔德，在一条名为 Beach Thorofare 的通航水道下方，以及大西洋城高速公路和在大西洋城和费城之间运行的新泽西运输火车线下方。

到 1990 年代，由于系统中的沙子和砂砾过多，钢管开始出现劣化迹象。“我们是一个海滩社区，”ACUA 总工程师 Tom Ganard说。“而且我们的行为会通过各种方式进入我们的系统——街道沙井、渗透、人们从海滩上下来和洗澡——而这些沙砾贯穿了整个管道。它实际上是在钢管底部穿了一个凹槽。”

Atlantic City Not Playing Games with its Wastewater System

Beautiful beaches punctuate the New Jersey coastline, but while sand is welcomed and appreciated along the ocean’s edge for visitors, it can wreak havoc on the pipes that comprise a community’s wastewater collection system. The Atlantic County Utilities Authority (ACUA) struggled with this firsthand when a critical force main line connecting three shoreline communities to the wastewater treatment plant began to fail.

The original 30-in. diameter, welded-steel force main that conveys wastewater from the towns of Ventnor, Longport, and Margate — a region referred to as Down Beach — was installed in the mid-1970s. It extends north from the Down Beach area toward the treatment facility. Along the way, it passes through a former municipal airstrip, Bader Field, under a navigable waterway called Beach Thorofare, and beneath both the Atlantic City Expressway and the New Jersey Transit train lines that run between Atlantic City and Philadelphia.

By the 1990s, the steel pipe began exhibiting signs of deterioration due to an excess of sand and grit in the system. “We’re a beach community,” said ACUA chief engineer Tom Ganard. “And we get a lot of beach sand coming into our system through various means — street manholes, infiltration, people coming off the beach and taking showers — and this grit runs through the line. It was literally wearing a groove in the bottom of the steel pipe.”

The 30-in. diameter HDPE PE 4710 pipe enters the HDD path to go under the Beach Thorofare waterway.

Photo courtesy of ACUA

After a series of failures in the line, the Authority sliplined a portion of the steel main coming from the Down Beach area up to Bader Field. But in 2017, the worst-case scenario unfolded. “I can remember exactly where I was on Sept. 23, 2017, when I got the call that you never want to get,” said Joe Pantalone, vice president of ACUA’s Wastewater Division. “That was the first main break of Bader Field.”

The ACUA acted quickly to bypass the line but it was only a temporary solution. The Authority knew it was on borrowed time and began the design and permitting process for the total replacement of a mile and half of force main. “Once we knew that we had problems in that one area, we immediately decided to replace the entire Bader Field main,” said Pantalone.

ACUA’s troubles weren’t over just yet. While in the design and permitting process, another catastrophic failure occurred in 2019, just south of the previous break. This kicked the project into overdrive, and the ACUA secured advanced permission to move forward with the total replacement it had already been planning.

The $8 million replacement project was divided into two phases: the first was the replacement of the Bader Field main line using a standard open-cut construction. This phase was completed in 2020 by Arthur R. Henry Inc. (Egg Harbor Township, New Jersey)

The second phase, which was not in failure mode but was part of ACUA’s master plan, is the portion running under Beach Thorofare, the Atlantic City Expressway, and the New Jersey Transit lines. General contractor C. Abbonizio Contractors (Sewell, New Jersey) used horizontal directional drilling (HDD) for this section, including the formidable 1,500-lf underwater segment.

For the HDD portion, the Abbonizio crew did a smaller 8-in. diameter pilot hole drilled to establish the bore path direction. At the point where it comes out of the ground, the crew reattached a larger-diameter bore — in this case, a 42-in. drill —and then pulled it back through the same path, making the hole the size needed for the HDPE pipe replacement. Then, the new pipeline was pulled through the opening.

C. Abbonizio subcontracted the HDD portion to Michels Corp., a family-owned and operated energy and infrastructure construction company headquartered in Brownsville, Wisconsin. The drill rig was a Uni 250×400 with a pulling force capacity of 250,000 lbs and a torque capacity of 40,000 ft-lbs.

The directional boring was completed in June 2021 and only took a few days. The accuracy of the drill was nothing short of amazing. “They literally hit the survey stake that was more than a thousand feet away that they had put in the ground at the exit point,” said Ganard. “Now, the pipe just needs to be connected to the current system on both sides.

“One of the benefits of using directional drilling is that it minimizes disruption to not only marine activity on the waterway but also the channel bed, water, and aquatic plants and animals in the bay. “The whole project is working in an environmentally sensitive area,” Ganard noted. “So, the fact that we could do the directional drilling really saved a lot of environmental disturbance that could be related to a construction project.” After installation, the pipe was approximately 80 ft below the Beach Thorofare.

“The entire process amazed me,” said Nicholas Listner, with the engineering department of C. Abbonizio. “More specifically, watching them track the pipe as it was drilled was definitely the most interesting part for me. There was a team guiding the drill head from an office. They knew where the pipe was at all time — both the location and the elevation.”

The HDD path for the HDPE pipe under the Atlantic City Beach Thorofare waterway.

Photo courtesy of ACUA

For both phases of the Down Beach force main replacement project, HDPE pipe was the material of choice. The 30-in. HDPE DIPS has an outside diameter of 32 in.

“We knew HDPE was a good solution for [this project] where we’re running at 60 psi,” Ganard said. “We had used it approximately 20 years earlier in another portion of our system, and when we inspected it, we did not see any signs of wear. We were comfortable that this pipe would have much better characteristics for what we’d be putting through it.”

According to the Plastics Pipe Institute, Inc. (PPI), the pipe can be used in methods of underground installation such as HDD or open cut. PPI is the major North America trade association representing the plastic pipe industry.

“A recent industry survey showed that HDPE pipe continues to be the most common type of pipe used in trenchless installations,” offered Camille George Rubeiz, P.E., F. ASCE, senior director of engineering for the Municipal and Industrial Division of PPI and is also the co-chair of the HDPE Municipal Advisory Board. “Properly designed, installed and fused, HDPE has a 100-year design life, zero allowable leakage, largest internal diameter and is the best water piping solution for open cut and trenchless installations. Plus, it has a larger flow capacity per PPIPACE.com, C coefficient of 150 — up to 50 percent higher C than others, corrosion and tuberculation resistance, lowest initial cost and lowest life cycle cost.

“The prevention of infiltration was one of the key benefits of the pipe here in Atlantic City. But a critical factor was also taken care of and that was because of the HDPE pipe’s inherent resistance to salt water. Plus, it has resistance to water hammer, fatigue, ground movements, freezing temperatures and earthquakes.”

According to Listner, several HDPE pipe companies were used on this project. The pipe was produced by Performance Pipe (Plano, Texas), a division of Chevron Phillips Chemical Company LP. A McElroy Mfg. Inc. (Tulsa, Oklahoma) Trackstar 900i butt fusion machine was used to join the straight pipe ends. The 45- and 11.5-degree bends were manufactured by GF Central Plastics LLC. (Shawnee, Oklahoma). Electrofusion couplings were produced by Integrity Fusion Products Inc. (Peachtree City, Georgia)

“The Down Beach force main replacement project is a massive undertaking that will resolve decades of challenges with a deteriorating steel pipeline. But for ACUA, it’s much more than that. “No one pays attention to the Wastewater Division until there is a failure,” said Pantalone. “This shows the community that we are diligent in our reinvestment into our infrastructure, we stopped the bleeding as quickly as we could, and we didn’t stop there. We really went the extra mile to carry out what we are pledged to do by replacing the entire main.”