Alleviating Neighborhood Flooding – Real-World Design
In August 2022, GKY and Associates, Inc. (GKY) submitted the Salters Creek Watershed Study report to the City of Hampton. GKY employed a combined 1D/2D model using PCSWMM to quantify existing condition flooding and then identified potential improvement projects to reduce that flooding. The study identified fifteen specific improvement projects to reduce the depth and frequency of flooding for a total cost of $16.5 Million in 2022 dollars. The study identified Gloucester Street neighborhood floods under existing conditions and recommended drainage improvements. Its outfall improvements were vital in lowering the hydraulic grade line in the area. The existing drainage infrastructure and existing topography (particularly the grading of individual lots) present challenges that sometimes cannot be solved with bigger pipes and culverts in the right-of-way. As multiple computer runs indicated, some areas flood due to lot grading and topography—not because the pipes are undersized. The City of Hampton contracted GKY to produce construction plans for Gloucester Street Drainage Improvements, Phases 1 and 2. The city identified several areas within the Gloucester Street neighborhood where citizens experienced recurrent flooding and asked GKY to investigate possible solutions. A topographic survey was conducted covering approximately 10,500 linear feet of public right of way. GKY designed drainage retrofits to increase stormwater conveyance and alleviate parcel flooding in the neighborhood. The low relief and extremely flat topography in the project area presented numerous challenges in designing standard-size inlets, curb and gutter, and large-diameter pipes. In addition, utility conflicts presented major hurdles. GKY employed real-world design to overcome these shortcomings, such as modified paved ditches, drop inlets, manholes, parallel or elliptical pipes in lieu of a single large diameter pipe, Class V RCP where the cover was limited, and regrading portions of the road. This presentation demonstrates real-world design in alleviating neighborhood flooding.Author Bio
Dr. Iyer is a Senior Water Resources Engineer with GKY and Associates in their Newport News, Virginia, office. He has over 40 years of professional and research experience in the field of water resources planning, development, management, and engineering. Dr. Iyer’s experience spans natural water system modeling, watershed management, hydrologic, hydraulic, bridge scour analysis, and stormwater management. Dr. Iyer is a PE, Certified Floodplain Manager (CFM), and Fellow of ASCE (F.ASCE). He serves on the board of directors for the Virginia Lakes and Watershed Association (VLWA). He is also an active participant of ASCE EWRI Task Committees.
