City of Grand Prairie Open Ditch Inventory & Assessment

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City of Grand Prairie, Texas
Our team was selected by the City of Grand Prairie to provide professional engineering services to inventory, assess, and develop an open ditch maintenance program for more than 35 miles of ditch systems. This evaluation included an analysis of the general condition and capacity of 15 ditch networks within the city and provides an organized and prioritized plan for future maintenance and improvements to these systems.
Our staff used handheld GPS devices (capable of sub-meter horizontal accuracy) and other tools to inventory pipes and drainage assets, measure ditch geometry and slopes approximately every 110 feet, and document the condition of the ditch networks within public right-of-way and easements. Additionally, more than 3,000 driveway culverts and other crossing structures that affect flow or ditch capacity were inventoried. Photographs were collected of each structure and ditch to further document existing conditions.
The resulting GIS database was then used to analyze the relative performance of each system within the study limits, ranking each based on capacity analysis and maintenance prioritization. Our engineers noted that many of the problem areas studied were constructed prior to current design standards and the advent of today’s hydrologic and hydraulic modeling capabilities or were constructed prior to the adoption of city ordinances which required the high level of design and analysis expected today. Therefore, the assessment focuses on improvements which will bring the infrastructure into compliance with current standards.
A conceptual improvement plan was prepared for each area, using consistent design methods, level of service, and unit cost data. Using factors such as the relative severity of flooding, overall condition, and improvement costs, the areas were ranked mathematically to provide a recommended order for addressing problem areas within the city. The final report includes “heat maps”, or visual representations of the areas that need capacity improvements the most. The report will be used in discussions with residents and city officials to develop a multi-year improvement plan.