Andrew G. Heydinger
Published: 1998
Total Pages: 124
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An investigation was conducted to evaluate prefabricated edge drain (PED) construction procedures and to assess the condition of PEDs installed in Ohio between 1988 and 1993. The research included a survey of department of transportation engineers in other states and Ohio Department of Transportation (ODOT) design and construction engineers. The condition of PEDs installed in Ohio was evaluated at six sites throughout Ohio by excavating short sections of PEDs for visual inspections and permittivity testing. A video borescope with a 25-ft (7.6-m) long fiber optic cable was used to investigate the in situ condition of the PED. Permittivity testing of the PED fabric was conducted in the field on PED samples removed from the excavations. Specifications for installing PED vary considerably among the states using PED. ODOT current specifications require placing the PED on the outside of the trench and using a granular backfill. Problems that have been reported include deformation of the PED core, compression of the filter fabric into the core, blinding and clogging of the filter, sedimentation of the core and blockage of drainage outlets. In most cases, the problems were considered minor. The problems cited above were observed at all six sites during the video borescope inspections. In spite of problems with the filter fabric, the permittivity of the filter fabric was not significantly reduced. The problems with PED result in reduced drainage capacity. However, the PEDs are effective in providing drainage provided the drainage outlets are not blocked. Construction specifications should be observed to minimize problems. Maintenance personnel should inspect drainage outlets on a regular basis to ensure that the outlets are not blocked.
