Dallas Wastewater Plan Delivers Dynamic Decision-Making Tool

The City of Dallas Comprehensive Wastewater Collection System Assessment Update was recognized with an Engineering Excellence Gold Medal from ACEC Texas and advanced to the American Council of Engineering Companies’ national competition.

Municipalities and water planning organizations are not strangers to master planning – the concept of evaluating and assessing water or wastewater infrastructure and determining future needs for updates and expansion to meet customer needs and operational demands. Most entities have separate models – hydraulic or risk, for example – but they are rarely merged into one tool, and many are compiled using proprietary software that is difficult to maintain.

Water/Wastewater master planning has served Dallas Water Utilities (DWU) well in some respects – an ordered list of projects to continually improve infrastructure. However, past plans were lacking in cohesiveness from other City departments, real-time data related to flow projections and rainfall, and new project developments that would ultimately impact the City’s infrastructure improvements. In addition, Dallas serves nearby customer cities with infrastructure needs that further impacted the system and called for a comprehensive tool to encompass a larger set of priorities and concerns.

Freese and Nichols created a hydraulic modeling and planning team that developed a solution for DWU – a CIP Prioritization Tool with capabilities for future updates, all while using off-the-shelf software. Overall, the project addressed population growth, regulatory compliance, aging infrastructure and organizational challenges plus new development and redevelopment areas within the City of Dallas and 11 wholesale wastewater customers.

DWU now has a dynamic resource for wastewater collection system planning and improvements, plus the ability to update it over time. This allows the City to evaluate, respond and budget for the most critical wastewater system needs based on current data and changing conditions over the next 25 years and beyond.

Innovative Application in Wastewater Collection System Planning

This project goes beyond traditional master planning and combines hydraulics and condition assessment into an off-the-shelf, usable software tool​​​​​​​ with the ability for updates. This shift in modeling is the future of master planning and a game-changer for DWU – no longer are they referencing a static list of projects to guide their infrastructure improvements. Instead, DWU now has a 25-year master plan based on extensive data and the ability to update priorities as conditions change.

The project’s dynamic CIP Prioritization Tool is innovative and unique. The Freese and Nichols team completed hydraulic water modeling in InfoWorks ICM and identified areas of growth based on population and predications from Dallas’ Planning and Urban Development Group. The process also encompassed aspects of Risk-Based Assessment (condition and criticality) combined with a number of other criteria, such as pipe age, material, inspection results and work order history.

Next, the team merged model data to create a CIP Prioritization Tool using InfoAsset Planner, which incorporated hydraulic components and facilitated decision making through a decision tree-based system to determine how projects should be selected and ordered.

This innovative integration of condition risk assessment and capacity analysis into a resulting dynamic CIP Prioritization Tool serves Dallas and its large customer base well through educated decision making for infrastructure improvements and budgetary considerations across many departments.

Design Considerations and Project Complexity

Prompted by the Texas Commission on Environmental Quality’s Sanitary Sewer Overflow Initiative, Dallas had a primary need for an updated wastewater collection system master plan every 10 years.

The model was built on historical monitoring data from 52 permanent flow meters that evaluate the wastewater collection system’s ability to convey dry- and wet-weather flows. An additional 28 monitoring locations (bringing the total to 80 flow meters) were recommended to further isolate the location of large inflow and infiltration contributions.

Master Plan Highlights

  • Model calibrated to within 5% of dry-weather flows and within 10% of wet-weather flows for 80 meters
  • Sensitivity analysis of several options for design storm, both in size and application
  • Coordination with wholesale customers to obtain hydraulic model results and improvement plans
  • Alternatives analysis of peak-flow conveyance and storage and optimization of existing conveyance capacity
  • Workshops conducted with DWU to review optimization of alternatives for capacity improvement alternatives in high-density corridors
  • Planning tool for identifying capacity improvement projects
  • Development of model update and maintenance protocol, as well as a manual for using the CIP prioritization tool

Elevating the Value of Master Planning

The new CIP Prioritization Tool provides Dallas with the ability to dynamically determine necessary projects as essential to wastewater collection system operations and maintenance. As a result, DWU can focus budgeted CIP dollars on projects that are truly needed based on priority versus completing projects that are “next on the list.”

From a holistic viewpoint, using the new dynamic tool for regular updates or projects is an innovative and different way of thinking. This approach allows CIP dollars to address existing problem areas and make improvements sooner in order to reduce the potential of negative impacts. In a dynamic sense, generating projects based on real-time, data-driven tools is a proactive approach to collection system planning as opposed to addressing project improvements when issues occur.

A New Platform for Proactive Wastewater System Management

The City of Dallas’ rapid growth and expansion called for a better way to address aging infrastructure and new system requirements. Freese and Nichols’ solution – a dynamic CIP Prioritization Tool for use over the next 25 years – met DWU’s project goals and more.

DWU’s operation and service to wastewater customers is now more efficient – projects are clearly identified using accurate data and line conditions. Validation is also present in model accuracy that coincides with flow meter data. This tool has transformed the way DWU manages budgetary allocations by providing a clear path for decision making, and DWU now receives cost savings by keeping projects in service versus opting for new construction in some cases.

With the new CIP Prioritization Tool, Dallas now has a dynamic tool at their fingertips to review data, input new findings and formulate decisions for wastewater infrastructure projects based on relevant and timely information. Further, the tool provides the backup needed for proposed projects and resulting benefits, with decisions based on current conditions to identify where dollars are best spent, all while facilitating a proactive – instead of reactive – approach to decision making.