Con Ed lays 10,000 ft. of 12-in HDPE pipe.
This high density polyethylene (HDPE) pipe was approved for use after Con Ed received test results from an independent evaluation and testing program. It was installed in a 10,000-ft. section of the gas distribution main that was completed last November and created the first natural gas link to businesses and residences in the area.
"By switching to Driscopipe 6800, we're saving thousands of dollars without sacrificing pipe performance and physical properties," says Anthony Mancino, Con Ed's engineer in Central Gas Technical Operations. Test results from Springboard Laboratories, Enfield, CT concluded that the HDPE pipe met all requirements of ASTM D2513 standard. "When all data were submitted and verified, we approved its use," Mancino added.
Con Ed has used Driscopipe 8000, a high molecular weight HDPE pipe, in high-pressure systems on its gas distribution grid over the past years and other Driscopipe products for the past 20 yrs. "When this project started in 1989, Driscopipe 6800 wasn't approved for gas installations, so we turned to another supplier to find a lesser cost alternative to 8000," Mancino says. "When 12-in. Driscopipe 6800 was approved, we launched our use of it on this project."
50-Ft. Length Advantage
Phillips Driscopipe, Inc., a wholly-owned subsidiary of Phillips Petroleum Co., saved Con Ed additional costs by supplying the pipe in 50-ft. joint lengths rather than the standard 40-ft. lengths. According to Mancino this "...saved us money on heat fusing costs...since longer pipe lengths meant fewer pipe sections were required for the job and fewer joints had to be heat fused. The savings were compounded when total labor costs saved, less heat fusing, and reduced transportation costs are considered."
According to Mancino the 10,000-ft. feeder line installation will increase system integrity of the region's gas system and enable potential residential and business customers to access natural gas through Con Ed. "This project has become a reality because of the large growth of gas in both industrial and residential usage in Westchester County. This new system can accommodate a two-way feed, strengthening gas supply reliability while increasing system safety and integrity," he says.
Overcoming Community Objections
To bring natural gas to this community which lies in the rolling hills of the lower Hudson River Valley took not only technical construction knowledge but also good public relations and education as well. Con Ed, a natural gas supplier to the Northeast for more than 170 yrs., familiarized local residents with the plastic pipe and its properties.
"At first, they didn't want us to put the system in. Some people associated gas installations with problems they had seen on national television," says Mancino. "Also, they expressed concern that we were using plastic and not steel pipe for this system. We are dealing with a community which is not accustomed to large construction installations. Most residents have water wells and septic tanks instead of municipal systems, so we had to educate them about gas pipeline installation," he added.
"We went to the town board to explain that Driscopipe 6800 is as strong and as good as steel for this application. We affirmed that Con Ed has been using plastic pipe for nearly 20 yrs. and nearly 75% of all gas distribution pipe installations in the U.S. today are plastic pipe--not steel," he continued.
Installation of the system also took Con Ed through the community's state-protected, designated wetlands area, which required implementation of several precautions in installing the pipe to protect this environmentally-sensitive area. "Some portions of the installation took us right on top of the wetlands. This challenged us to impose the least possible strain on the area," Mancino said. "We set up hay bales and silt screening to protect the area from any dirt or debris caused by our installation. Also, we secured drain crossings so that any soil displaced by our installation wouldn't flow down the town's drainage system when it rains."
Construction And Installation
It took six months to obtain the necessary town, city, and state permits before construction could begin on the 10,000-ft. gas link. Felix Industries, Lincolndale, NY, a Con Ed certified contractor, was awarded the contract to install Driscopipe 6800. The company has installed several HDPE installations for Con Ed in the past and reports that Driscopipe 6800 was easy to handle, heat fuse, and install.
"We rarely experience any nicks or damage of any kind when installing this pipe because of its durable structure," says Scott Reilling, foreman of the Felix crew. "Steel is more difficult and tedious to install because it's heavier; and you don't have the same leeway of absorbing shock without damage as you do with Driscopipe."
Installation of the 1.9-mile system required digging a 3 1/2 ft. wide trench that was 4 1/2 ft. deep to accommodate the 12-in. pipe. The trench was partially filled with gravel, a polypropylene film barrier (in high drainage areas), and sand before pipe was laid. Each 50-ft. section of Driscopipe weighs approximately 900 lbs. and were heat fused by certified technicians which were approved by Con Ed. Pipe was fused on McElroy 412 heat fusion equipment.
Pipe was then laid in the trench with a Caterpillar 214 backhoe equipped with a sideboom. "The sideboom is the key to installing 12in. pipe because it the pipe parallel to the trench, ease it in, and keeps moving up and down the road," says Reilling.
Editor's Note: Driscopipe, Driscopipe 8000, and Driscopipe 6800 are registered trademarks of Phillips Driscopipe, Inc., a division of Phillips Petroleum Co., 2929 N. Central Expressway, Suite 300, Richardson, 7X 75803