DWU Major Rehab of Raw Water Facilities

Lake Ray Hubbard is the preferred raw water source for the Eastside Water Treatment Plant (ESWTP), Dallas Water Utilities’ (DWU) largest WTP. Raw water from Lake Ray Hubbard is conveyed through Forney Pump Station (PS), making the reliability of Forney PS critical in meeting system-wide water demands. Forney PS contains six 1000 HP Raw Water Pumps with a total capacity of 300 MGD. Two of the six pumps are variable speed, and the other four are constant speed. 

This project began as a Raw Water System Master Plan for DWU that covered a large geographic footprint, ranging from Lake Fork to Fishing Hole Lake near Bachman WTP. We evaluated the condition and risk of over $1B of DWU's raw water assets and developed a comprehensive prioritization mechanism to determine a risk-based capital improvement plan (CIP). This raw water system CIP covers the next 20 years and is based on criteria developed specifically for DWU. 

Garver was contracted to complete final designs of the highest priority improvements from this master plan, which included Lake Ray Hubbard Intake, Forney PS, and Forney Dam. Specialized investigations, evaluations, detailed engineering designs, bidding assistance, and construction support services were provided to continue the initial raw water rehabilitation project. The goal of continued evaluations was to collect additional data in the field on each raw water pump and its ability to effectively convey raw water to ESWTP. 

To provide the best value design to DWU, we conducted wire-to-water testing to determine pump efficiency and make recommendations for pump replacement. These investigations showed that a new pump design and implementation of recommended energy efficiency measures would result in increased pump efficiencies that could save DWU up to $125,000 in annual energy costs.  

We also tailored key performance indicators (KPIs) to meet the needs of DWU staff. Pumping KPIs will be programed into the WTP SCADA system for monitoring and trending, allowing pumps to operate in the preferred operating range daily.  

We also completed final designs to address major rehabilitation items as well as performance limiting factors noted during assessments and additional investigations. Along with significant improvements at Lake Ray Hubbard Intake, Forney PS improvements included: replacement of three raw water pumps, magnetic speed drives, and motors; replacement of all suction and discharge valve assemblies for raw water pump trains; HVAC improvements to optimize airflow through the pump station; controls improvements to allow for better monitoring and proactive maintenance of the pump station; and other miscellaneous rehabilitation items. Final designs were completed in December of 2021, and the project is currently halfway through construction with anticipated completion by summer of 2024.