This paper documents the installation and performance ofN-12 pipe installed during construction of South Forbes Road in Fayette County, KY 54 in Daviess County, US 62 in McCracken County, Nicholasville Road in Fayette County, and US 68/KY 80 in Warren County. The pipe is manufactured by Advanced Drainage Systems, Inc., and is designated as ADS N-12. ADS N-12 is a corrugated high-density polyethylene (HDPE) pipe. The pipe has a corrugated exterior for increased strength and a smooth interior to provide maximum flow capacity.

The N-12 pipe requires less equipment and fewer personnel than steel or concrete pipe for installation. From visual observations at all five sites, extreme care should be taken during backfilling around the pipe above the bedding material. On US 62, KY 54, and US 68/KY 80 the pipes were not completely covered with bedding material. Cuts or tears were found inside the N-12 pipe (5 total). It appears that the tears are occurring where the sections of plastic are wrapped together to form the pipe. The rips are probably occurring due to improper backfilling and unequal loading of the pipe wall. On Forbes Road and Nicholasville Road, the pipes were completely covered with one foot of either sand or crushed stone before the excavated material was placed as backfill. This one-foot cover helps protect the pipe against backfill damage. In several installations, it was apparent the ends of the pipes at the couplings were rarely butted completely together. This permits material to be deposited in those areas. Care should also be taken during construction not to damage the plastic pipe during transportation. Due to the fact the N-12 is lightweight, the pipe has a tendency to rise or drift during backfilling. To eliminate this, the contractors bed each side equally to approximately 1/2 to 3/4 of the pipe height before compacting (depends greatly on the backfill material).

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The contents of this report reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, nor the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names and trade names are for identification purposes and are not to be considered as endorsements.