Large-diameter corrugated HDPE pipe up to 24 inches will be used for all of the sections that require in-filling of the ditch system.
The HDPE pipe can stand up to the weight of the deep fill provided it is installed correctly with appropriately compacted backfill materials.
According to the Plastics Pipe Institute Inc. (PPI), corrugated HDPE pipe used in a ditch enclosure is usually shallow and can experience traffic loadings if installed at road crossings. Properly installed, the pipe can withstand AASHTO HS-25 loads with a minimum of 1 foot of cover for diameters up to 48 inches and 2 feet for larger diameters. If installed under pavement in colder climates, the institute recommends 2 feet of cover or half the pipe diameter, whichever is greater.
The corrugated HDPE pipe, SolfloMax from Canadian manufacturer Soleno Inc., is made with a bell with an integrated, gasketed spigot for watertight performance.
In addition to removing runners and cyclists from the road's shoulder, enclosing the roadside ditch mitigates mosquito breeding.