State of Technology Report for Force Main Rehabilitation, Final ...

4.1
4.0 TECHNOLOGY SELECTION CONSIDERATIONS
Aside from selecting renewal technologies on the basis of their fit to the force main’s operating conditions
(e.g., pressure, burial depth, etc.), other site-specific parameters must be considered in the selection
process. The life-cycle cost of the renewal method and its impact on extending the life of the asset are
often the primary concerns in technology selection. Other site-specific factors that should be taken into
consideration include post-renewal capacity needs, accessibility, future O&M requirements, the condition
of the host pipe, and the consequence of its failure (criticality). All of these items are explored here. As
discussed in Section 5, other technology-specific factors that play a role in technology selection are
corrosion resistance, long-term HDB, temperature derating, duration of by-pass pumping, use of nonstandard
pipe materials and dimensions, and the methods for reinstatement of fittings and connections.
Life-Cycle Costs
Renewal technology selection is guided by consideration of life-cycle costs over the remaining life of the
asset or its extended life with the renewal. In principal, the concept is to break down all costs associated
with an alternative (including the alternative of doing nothing) into a net present value for comparative
purposes by discounting future expenditures and the remaining salvage value of the asset. Present costs
would include the capital funds needed for renewal of the underground asset including engineering and
construction. Each alternative may also have a different life expectancy and different future O&M costs.
In surveying vendors of rehabilitation products, they were each asked to provide capital costs and some
guidance on the nature of future maintenance that might be required for their technology. Without
exception, all replied nothing out of the ordinary was needed for O&M. Cost data were collected to the
extent possible as outlined in Appendix A. However, the availability of this data was limited. Figure 4-1
illustrates representative cost data from a collection of bid tenders from across the US on various
trenchless installation methods (Simicevic and Sterling, 2003). These costs were collected in 2002 and
2003, so current costs will be higher, but the relative comparison is still valid.
Figure 4-1. Total Installation Cost in 2003 Dollars for Trenchless Rehabilitation Methods
(Simicevic and Sterling, 2003)
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