Evaluation of Alternatives Incorporating Substantial Water Reuse

During scoping and other meetings, the public expressed an interest in an alternative with water reuse. Reuse is the intentional diversion of water that is at least partially composed of treated wastewater and subsequently treated for use. Indirect reuse indicates that there is no direct connection between a wastewater effluent discharge point and the reuse water treatment point. Potable reuse refers to water that is reused for human consumption.

Once water reuse was no longer a part of Colorado Springs’ No Action Alternative, none of the remaining SDS alternatives had a large water reuse component. As a result, Reclamation developed and analyzed several potential alternatives that included substantial water reuse. The evaluation of reuse alternatives that occurred after the No Action Alternative was modified in February of 2007 is discussed in the SDS EIS Alternatives Analysis Addendum.

Six indirect potable reuse alternatives were evaluated. Each of the reuse alternatives would involve reuse by Colorado Springs only, and not the other Project Participants.

In addition to the six new reuse alternatives, Alternative 6, the Downstream Intake Alternative, was considered a reuse alternative. The Downstream Intake Alternative includes a water intake on the Arkansas River downstream of Fountain Creek, resulting in a portion of Colorado Springs’ reusable return flows captured in the intake. The portion of Colorado Springs’ water supply that would originate from reuse in Alternative 6 would be about 16 percent.

The six new reuse alternatives considered were various combinations of Colorado Springs’ Fountain Creek reusable return flow diversions, storage of reuse water, and treatment of reuse water. In order to provide a water supply that would be protective of human health, each of the reuse alternatives would include advanced water treatment including at least a portion of the reuse water treated using reverse osmosis. Reverse osmosis would pass reuse water through a membrane that would effectively remove contaminants including salinity. Each of the reuse alternatives would also use blending of reuse water with an Arkansas River water supply from Pueblo Reservoir. This results in a water supply of about half reuse water and half Arkansas River water.

The reuse alternatives were screened using the same process used for the original seven SDS alternatives described in the March 2006 Alternatives Analysis Report. The screening process included screening for significant issues, general environmental issues, reclaimed water treatment effectiveness (new criteria added since original alternatives screening), SDS EIS purpose and need and cost screening, and scoping theme screening. Each reuse alternative passed the screening criteria for significant issues, general environmental characteristics, reclaimed water treatment effectiveness, and purpose and need screening. However, none of the reuse alternatives passed the cost screening criteria. To pass cost screening, the cost needed to be less than $25,000 per acre-foot per year of firm yield and $21,000 per acre-foot per year of average yield. The cost for the reuse alternatives ranged from $68,150 to $76,290 per acre-foot per year based on firm yield and $57,880 to $65,690 per acre-foot per year based on average yield. Additionally, none of the reuse alternatives better responded to responded to significant issues from public scoping than the existing alternatives. As a result, none of the reuse alternatives will be carried forward for detailed analysis in the SDS EIS. The evaluation of reuse alternatives is described in detail in Reclamation’s Alternatives Analysis Addendum.