2. Maintenance & Repair

3. Renovation

4. Replacement & New Installation

1. Introduction

The increased public concern about the environment and the deteriorated condition of
our infrastructure have led to the need for rehabilitation and new installation of our
underground utilities. The traditional methods of dealing with underground utilities are
open excavation or trenching. Trenchless technology, which includes a large family of
methods, is emerging as a practical alternative to solve these problems.

When considering rehabilitation or new installation, two things need to decided: the
demands on the system and the cost associated with it. The costs associated with any
construction activity are direct costs of construction, indirect costs and the risk to the
public, and operating and maintenance costs of the completed systems. A comparison of the direct costs of construction between traditional methods and trenchless technology shows that trenchless methods may be more or less costly, depending on the situation.

The direct costs are not the only costs to be considered. The indirect costs and the
risk to the public are very important. Trenchless technology has a great advantage in this field. Some of the indirect costs associated with traditional methods are:
1) lost revenue to business along the utility line,
2) traffic delays caused by restricted roads and detours,
3) reduction of life of the repaired road, and
4) delay costs caused by court injunction to the municipality for loss of revenue to businesses. Trenchless technology reduces these problems to a minimum. The risk to the public is also greatly decreased with the absence of open trenches along the streets.

The operating and maintenance costs of a system can be decreased by using trenchless technology. Operating expenses are composed mainly of lift stations and forcemains, which can be eliminated by using gravity flow systems. The ability to drill against the grade can eliminate many lift stations. The costs of using trenchless technology do not increase with depth as dramatically as with traditional methods, making the overall costs less.

The environmental benefits of trenchless technology are noticeable when working near
rivers and streams and environmentally sensitive areas. The ability to install or
rehabilitate utilities without disrupting the surface is essential. The noise produced
using traditional methods also causes a general disruption to business and residential
areas, which can be reduced by using trenchless technology.


The requirements of the system are also effectively met. They perform just as well as
traditional methods, better in some situations. Repair and renovation of systems can not only stop leaks but increase the structural integrity of the system. If larger flows are
required, trenchless methods can remove the existing pipe and insert a larger one,
allowing for increased demands.


The services provided by trenchless technology can be divided into three main
categories:
1) maintenance and repair,
2) renovation, and
3) replacement and new
installation. The services provided and the techniques available for each category range from video inspection to sliplining to directional drilling and a great number in between.

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