Integrated Pipeline (IPL) Raw Water Conveyance to the Bachman Water Treatment Plant Study

With recent population increases and projected growth in the North Texas area, available drinking water during drought conditions is a growing concern for water providers. In conjunction with Dallas Water Utilities (DWU), HDR evaluated alternatives to identify the best apparent method to convey 150 MGD of raw water to the Bachman Water Treatment Plant (WTP) by 2027 for drought prevention and to meet water supply requirements in North Texas. Early stages of the project involved HDR and DWU identifying ten alternatives for preliminary evaluation and developing non-cost evaluation criteria and weights for the comparison and scoring of alternatives. Benefit scores and planning-level costs were input into the cost-benefit decision tool to facilitate decision making and provide justification for the path forward. By applying the cost-benefit approach, the five most favorable alternatives were identified for further evaluation. A hybrid of two alternatives providing additional blending benefits, phased construction, and operational flexibility was also developed and included for consideration. Final evaluation of alternatives resulted in selecting the hybrid alternative, which initially included a phased implementation and involved approximately eight miles of open lake conveyance and 22 mi of up to 96-in. diameter hard-pipe conveyance, as the best conveyance method. Future project phases would require additional pipeline and a pump station. After refining the hydraulic analysis for this alternative, the project team determined that the pipeline diameter could be reduced to 90 inches; and with additional tunneling, the full 150 MGD could gravity flow to the Bachman WTP, eliminating the need for future project phases. HDR is finalizing the preliminary design on the selected alternative that includes an Implementation Plan to assist DWU with project delivery and phasing, staffing, permitting requirements, property acquisition, and project funding.