Building a suitable endwall for drainage pipe can often be a challenge. In addition to the physical requirements–preventing erosion at the outfall location, resisting scour–appearance is a consideration in many places. And although flat walls might be easier to construct, flared or winged endwalls can help direct outflow and protect the embankment.
Needing endwalls in several locations last spring, engineers in the suburbs of Pittsburgh, PA, considered a number of options. Concrete works well but is expensive and time-consuming to install. Other treatments, such as block, stone, and ties, are easier to install but often result in maintenance problems down the road.Bob Robinson, township engineer of O’Hara Township, PA, came up with a different solution: prefabricated endwalls. “They were easier to install and a lot more economical than other endwall systems,” he comments, noting that two workers took approximately an hour to install one system. Made entirely of plastic–linear, low-density polyethylene–the endwalls simulate the appearance of stone and have a consistent appearance. The relatively new HartmanEW System, manufactured by HartmanEW Inc. in Pittsburgh, consists of four pieces: a base section that serves as the main body of the endwall and has an opening for 18-in. plastic or 15-in. concrete pipe; an additional section to adjust for height and depth requirements of the pipe; a lid section; and a ring adapter for 18-, 15-, or 12-in.-diameter pipe. An assembled unit is 3 ft. high, 5 ft. wide, and 1 ft. deep, although the height is adjustable by adding additional segments between the base and the lid section. A standard four-piece unit weighs less than 100 lb. Rob Nymick, chairman of the Center Township, PA, Board of Commissioners, purchased eight units. “There’s a big installation savings compared to concrete,” he notes. “One person can pick up the system and set it in place while the rest of the crew continues to dig the trench line and install pipe. In order to install concrete endwalls, I would have to pull three guys off the trench line.” Although the light weight is good when installing the endwall, something sturdier is needed for the long haul. The system has a hollow base that can be filled on-site with a variety of materials, from sand to concrete to scrap materials, helping to anchor the pipe.
