GIS-Based Data Management and Visualization for Stormwater Asset Management and Planning

The Chagrin River-Lake Erie Direct Tributaries (CHALET) Stormwater Master Plan (SWMP) Study advanced the Northeast Ohio Regional Sewer District's efforts to protect Lake Erie, critical infrastructure, and over one million residents by addressing flooding, erosion, and water quality problems associated with stormwater runoff in the Cleveland Metropolitan area. Regional assets that receive and convey stormwater were evaluated throughout the 86-square-mile drainage area using a combination of field inspections and hydrologic and hydraulic (H&H) models. Field geomorphic inspections of waterways and stormwater basins were conducted through streamlined technology. Fifteen subwatershed models of the study area were also developed to identify flooding problems. Condition ratings for assets within the regional stormwater system (RSS) were then developed using standardized GIS data processing that integrated field inspection and modeled flooding results. Areas with poor ratings were grouped to define problem areas, and cloud-based GIS access facilitated the development and evaluation of alternative improvement projects. The resulting CHALET SWMP delivered a prioritized list of construction projects and operation and maintenance activities to reduce flooding and erosion risks and enhance stream health throughout the region. This presentation will focus on how inspection data and modeled flooding results were classified following the District's standards, integrated, and shared among the project consultant team to systematically compare risks across the study area and develop improvement plans. This process will be illustrated by focusing on one of the resulting 47 problem areas. This case study demonstrates how structural, hydraulic, and sedimentation and debris risks were flagged throughout the RSS and holistically considered when developing improvement projects. Key technologies that facilitated data collection, asset performance evaluation, and alternative development will also be highlighted. During the data collection process, culverted streams were inspected using closed circuit television, while stormwater basins and open channel streams were inspected through the ArcGIS Survey123 platform. These inspections produced numerous videos and photographs that were shared back with the District and hosted on their ArcGIS Online (AGO) platform. These inspections resulted in condition assessments with ratings for structural integrity and sedimentation and debris. These ratings for basins and streams were added into the GIS dataset used in the subsequent performance evaluation. In addition to the inspection data, open channel spherical imagery was collected throughout the study area. These 360-degree views of the streams were linked to a GIS dataset so that the consultant team could easily verify inspection results and develop improvement projects. This Google Street View-like tool proved invaluable for increasing the efficiency of desktop-based analysis, thus minimizing the need for return trips to the field. The CHALET SWMP team developed 15 H&H stormwater models using PCSWMM. These models drew on field inspections, flow monitoring, and spherical imagery. The PCSWMM models were used to predict flooding with the planning focus being, when feasible, to develop solutions that would avert flooding at the 100-year design storm event. Hydraulic condition ratings for RSS assets (culverted stream, basins, crossings, and streams) were based on the flooding depths of nearby buildings, roads, driveways, and other transportation assets. Using the District's standards, a condition rating related to flooding depth and a criticality rating related to asset importance were assigned to each building and transportation asset. More important buildings and roads, such as hospitals and highways, had higher criticalities than less important assets, such as residential garages or local streets. Condition ratings and criticalities of the RSS and associated buildings and transportation assets were combined to develop business risk exposure (BRE) scores in a comprehensive GIS dataset. Assets with high criticalities and poor condition ratings for structural integrity, hydraulic performance, and/or sediment and debris resulted in the highest BRE scores. Problem areas were delineated where multiple assets in close proximity had high BRE scores. Improvement alternatives were then developed for each area. Standardizing GIS data management of inspection results, generation of condition ratings, assignments of criticalities, and calculation of BRE scores supported data-driven performance evaluations and solution development. One problem area in the Euclid Creek East subwatershed serves as a case study for how comprehensive data management facilitated evaluating asset performance and improving regional stormwater management. Along this portion of Euclid Creek East Branch, inspections identified debris accumulation at a basin inlet, a failed crossing, and high criticality buildings near an eroding stream bank. Modeling predicted flooding of local roads. When considered together through the GIS database operational performance evaluation, this portion of the East Branch was flagged for problems stemming from hydraulic performance, structural integrity, and debris accumulation, and a problem area was defined. A set of baseline recommendations and two alternatives addressing flooding were created. The alternative that reduced the risk most effectively and efficiently was then recommended to the District in the SWMP. With standardized GIS data delivery, recommendations from this SWMP, in addition to the District's three previous SWMPs, can now be integrated and shared with internal District stakeholders, enabling the District to comprehensively present problem areas and recommendations across their entire service area. ArcGIS Online and the Enterprise Portal offer a dynamic and interactive method for effectively sharing SWMP recommendations. Results from this data-driven planning process now serve to prioritize nomination of improvement projects to the District's design and construction plan or for advanced stormwater planning.