The new storm water drainage system being installed here is using large diameter corrugated high-density polyethylene (HDPE) pipe to replace an old clay tile pipe system.
According to the Plastics Pipe Institute Inc. (PPI), this project represents the next step in the Georgia Department of Transportation’s (GDOT) initial consideration of 60-inch diameter HDPE pipe for these types of projects. PPI is the major trade association representing all segments of the plastic pipe industry.
“The GDOT has long approved the use of corrugated HDPE pipe in smaller sizes up to 48 inches in diameter for culverts and under-road drainage systems,” stated Tony Radoszewski, president of PPI. “Just as other state DOT’s have done, Georgia has consistently been expanding the approval of HDPE pipe products.”
Located southeast of Macon, GA, and with a population of 9,700, Fort Valley embarked on rehabilitating its storm sewer system in September 2013. The $8.5 million project consists of replacing the terra cotta pipe, curb and gutter and sidewalk along SR 49 between SR 96 and the CSX Railroad. In addition, the drainage system extending from SR 49 to near College Street and the culvert near the intersection of SR 96 and US 341/SR 7 is also being replaced. The project is scheduled to be completed by the end of April 2014.
For the initial run, 1,180 linear feet of 60-inch diameter NFlow corrugated HDPE pipe from Southeast Culvert Inc., Winder, GA, was used. “In addition to the favorable flow rates and strength, the pipe also has the ability to stand up to a wide range of pH values,” stated Dan Currence, P.E. director of engineering for the PPI’s CPPA division. “In this area of Georgia the soil pH has been recorded as low as 3.40. This extremely acidic soil would negatively affect other pipe materials such as concrete and steel.”
Burial depth of the pipe ranged from 10 to 20 feet along the pathway using GDOT Class II material for backfill and a graded aggregate bed. Properly installed corrugated HDPE pipe can withstand AASHTO HS-25 loads with at least one foot of cover for pipe 48-inches and smaller, or two feet of cover for larger diameter pipe. This allows for driveways, access roads, parking lots, and similar structures to be built above the system. The 60-inch pipe also meets the specifications of AASHTO M294 for dual-wall corrugated HDPE pipe.