In Summer 2013, the City of Laconia, New Hampshire, located along the shores of Paugus Bay and Lake Winnipesaukee needed to replace a failing concrete box culvert on Mechanic Street and turned to Contech’s New Hampshire office for assistance. The city has routinely utilized M-294 HDPE pipe in the past but this proposed storm sewer was running under the existing road and longitudinal to it for about 500 feet and had areas with only 12” of proposed cover from the pipe to the bottom of the asphalt, well outside the minimum cover limits of 24” for AASHTO M-294 pipe. The compact wall of the 36” steel reinforced PE pipe (OD =37.1”) also helped to improve the cover limitations versus the thicker- walled M-294 pipe (OD =42 “).
The City of Laconia Department of Public Works was very pleased with the pipe selection and installation by their maintenance contractor, Busby Construction of Atkinson, NH. According to Paul Busby, President of Busby Construction, the reinforced bell and spigot joints (15 psi that exceed the joint tightness requirements) joined together very well. There were a few drains with unknown locations that were easily tapped into by the new DuroMaxx pipe as the old box culvert was removed. The Duromaxx was simple to cut with a sawzall through the 80 ksi steel ribs and the pressure rated polyethylene resin.
Paul Moynihan, P.E., DPW Director, commented, “Our DPW Project Inspectors were very impressed with the ease of handling and assembly of the 36” DuroMaxx pipe. The entire main barrel (500’) was installed in about 5 to 6 days. This efficient installation rate along with the fact that the ordering and delivery of the pipe was turned around in just over two weeks, enabled Laconia to stay on track with completing the 2,300 ft. street rehabilitation project (which included this drain replacement) on schedule”
Overall this was a highly successful installation in the tight confines of an urban street, and the pipe is designed for HS-25 live load and LRFD for as shallow as 12” of minimum cover.