Civil Engineering Reference
In-Depth Information
100 mg / L) nitrate concentrations. Other major sources may include liquid wastes and
bacterial fixation of atmospheric nitrogen.
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EVALUATION OF WATER SUPPLY ALTERNATIVES
Water supply is the most fundamental requirement of an urban community. As such,
water can be considered a least cost commodity. It isn't a question of
whether
people
will choose to purchase water, only how much it will cost, and the magnitude of the
other consequences. Water supply planning must consider both cost and non-cost fac-
tors in selection of a preferred plan. Cost factors include capital, operation, mainte-
nance, and replacement costs, and rate impacts. Non-cost factors may include
reliability, environmental impacts / benefits, public acceptance, drought resilience, water
budget impacts, groundwater quality impacts, responsiveness to future regulatory
changes, compatibility with phased construction, institutional complexity, funding
complexity, and ease of implementation. A rating system can be employed to evaluate
and rank the various water supply alternatives (Table 8-5).
TABLE 8-5. Sample Water Supply Alternative Ranking Criteria
Alternative
Criteria
1
2
3
Ability to meet water supply objectives
Capital cost (ability to fund)
Ability to phase construction
Rate impacts
Ease of implementation
Balanced water budget
Reliability
Drought resilience
Groundwater quality protection
Surface water quality protection
Response to environmental regulation changes
Response to drinking water regulation changes
Environmental impacts
Accommodates land use objectives (accommodates
or constrains growth)
Impacts to other stakeholders
Totals
Note:
Alternatives are rated based on a 1-3 or 1-5 scale for each criterion, then totaled at the bottom of each
column. Weighting factors can also be used to amplify certain criterion, if desired.
