Recycling Treated Municipal Wastewater for Industrial Water Use

TM3: Recycled Wastewater System Components and Costs
Recycling Treated Municipal Wastewater for Industrial Water Use
5.3 Cost Model
A cost estimating tool was developed to evaluate the costs for a range of reclaimed
water systems to serve industries a water supply. The cost tool is based on the
conceptual system model shown in Figure 1, for those facilities on or originating on
the WWTP site. There are four major facility components to the cost model:
Treatment (includes residual disinfection)
Storage
Pump Station
Piping (transmission)
Each of these facility components is addressed in a separate module within the
spreadsheet-based cost tool. Different system configurations can be evaluated to
provide the estimated costs for a given supply water quality, quantity supplied, and
distance of the industry from the WWTP. The model provides the transmission
system costs for a specified flow and distance from the WWTP to the point of
delivery.
The cost model is predicated on treatment being provided on the WWTP site and
water delivered with the prescribed water quality at a delivery pressure of 40 psi. The
water quality delivered will depend on the treatment processes used. The base system
will deliver quality with the characteristics listed previously in Table 6. The model
does not include costs for treatment facilities at the industry site or booster pumps to
meet industry specific requirements. An industry with more stringent water quality
or pressure requirements would likely have existing facilities on their site to treat the
reclaimed water supply.
The cost model was used to develop cost curves for a range of industrial water
demands and transmission distances. Capital costs are annualized based on a 20-year
debt service and presented as a cost of service, in $/1000 gallons, in conjunction with
all major O&M costs. The cost of service provides a unit of measure that can be
compared to existing water supply costs.
An example of the cost model summary spreadsheet, shown in Table 13, provides the
assumptions used for the base system and presents estimated costs for a reclaimed
supply of 1.0 mgd (annual average) delivered 1.0 mile. As with other transmission
cost information, this assumes a peaking factor of 3, or maximum flow of 3 mgd. The
average annual flow/demand and length of transmission piping are the main input
parameters.
Other spreadsheets in the cost tool determine the capital costs for treatment, storage,
pump station, and piping and annual pumping power costs based on the flow and
pipe length input. Assumptions for unit costs of O&M items not presented in Table 12
are shown in Table 13. These include equipment maintenance, laboratory sampling
and analysis, and general administrative costs.
30 Craddock Consulting Engineers
In Association with CDM & James Crook
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