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