Constructibility review and economic analysis for the installation of large-diameter HDPE drainage pipe

Date

2000-08

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

This thesis documents the findings from a constructibility review and an economic analysis for the installation of large diameter High Density Polyethylene (HDPE) pipe for gravity flow storm drainage. Pipes of diameter 18 in., 24 in., 30 in., 36 in., 42 in. and 48 in. have been considered in the above analysis. The constructibilty review and the economic analysis described here were performed as a part of a research project that was sponsored by Texas Department of Transportation (TxDOT). A draft specification was developed for HDPE pipe installation as the primary objective of the above research project. Deficiencies in several areas of the draft specification were figured out through a formal constructibility review approach that have been documented in this thesis. Revised recommendations are incorporated into the final specification on four areas: minimum trench width requirements, addition of cement stabilized backfill as a new backfill type, gradation requirements for granular backfill, and minimum cover requirement above the pipe crown. Large-diameter HDPE pipe is prone to flexural deflection and it withstands the load exerting on it by the structural integrity of the pipesoil system. Revised recommendations were made with a view to conduct high quality installations with HDPE pipe with suitable backfill materials. Any quality improvement though constructibility review involves extra money. Therefore, the economic analysis part of this thesis analyzed the economics of HDPE pipe installation projects with respect to installation with other traditional pipe products, such as RCP and CMP. The analysis resulted in a comparative picture between HDPE and RCP from the viewpoint of economics. However, all the cost figures used in this analysis were present value of the resources. Significant savings was estimated from using HDPE over RCP under many resource availability conditions. Despite the stringer installation requirements of HDPE pipe compared to RCP, analysis of data from real projects and hypothetical projects showed that HDPE pipe can be cheaper if some locally available suitable backfill material can be procured to the project site at a reasonable cost.

Description

Keywords

Drainage pipes -- Cost effectiveness, Underground plastic pipe

Citation