Crawling through several hundred feet of an active storm sewer pipe can help make up your mind about approving it. When Jeff Martin, P.E., materials engineer for the Kansas City, Mo. (KCMO), public works department, got a look at high-density polyethylene (HDPE) pipe from the inside out, he was convinced.
Martin and members of the KCMO Standards Committee visited HDPE installations in neighboring Johnson County, Kan., where HDPE pipe has been used for several years. They inspected pipe with diameters greater than 36 inches that had been in the ground for more than five years. The team crawled through hundreds of feet of 10-year-old pipe up to 48 inches at a shopping mall, and walked through hundreds of feet of 5-year-old, 60-inch-diameter HDPE at a residential subdivision. The pipes and joints were in excellent condition.
After the inspection, the committee received further information on HDPE's benefits in storm-sewer applications. A majority of members present agreed to allow its use, and Section 2602 of the specification was amended to include corrugated HDPE pipe.
“This approval is something I've been open to, and it had been in the works for a long time,” said Martin.
Dan Currence, P.E., regional engineer at Advanced Drainage Systems in Hilliard, Ohio, said new faces at KCMO were key to the long-awaited acceptance. “With the newer faces came new attitudes and minds open to where the future of this industry is going,” said Currence.
Prior to working in Kansas City, assistant city engineer Greg Rokos, P.E., had worked for the state, which recently had approved use of HDPE pipe. The city followed the state's lead by specifying that all HDPE pipe must comply with the Plastics Pipe Institute's third-party certification testing.
“The fact that we had already been written into the state's spec carried a lot of weight for Greg,” said Currence. “Showing him about 3 miles of a pipe project in West Plains on Missouri Highway 63 also proved a lot to him.”
The PPI pipe certification program consists of random, unannounced inspections at manufacturers' facilities by a third-party administrator to evaluate material, dimensional, and physical performance properties as specified in American Association of State Highway and Transportation Officials (AASHTO) M294/MP7 for 12- to 60-inch pipe. If the pipe complies with all requirements and the quality control program is satisfactory, PPI will list the pipe on its Web site, and the manufacturer may mark the product with the Certified Products Seal.
“The main advantage for us to the certification of the pipe is getting a handle on the quality of the material we're putting in the ground,” said Martin. “It's impossible to go out and touch every piece of pipe that is installed on every project. But that third-party verification means that someone else has done that for us, and we're confident in the product.”
Corrugated HDPE pipe is available with soil-, silt-, and watertight joining systems. These integral joints meet stringent standards mandated by the U.S. Environmental Protection Agency in new legislation and comply with American Society for Testing Materials (ASTM) and AASHTO specifications. O-ring rubber or elastomeric gaskets, conforming to applicable ASTM standards, are used in the silt-and watertight systems.
Also vital to the new spec were pending federal regulations that may require watertight joints in all storm sewers. With advancements in HDPE pipe technology, watertight joints are more common than before. On a plant tour, Martin observed the manufacturing process and the way joints are tested. “Observing the joint test on the pipe removed any doubt about the water tightness of the pipe joints,” said Martin.
—Tanya Rouce is communications manager for the Plastics Pipe Institute.