Fitting an MTD into a Developed Neighborhood – Challenges and Solutions
Salem Village, a developed neighborhood in Virginia Beach, currently discharges to a volume-control wet pond with an 18.2-acre drainage area. The neighborhood was constructed before current stormwater management regulations requiring water quality treatment. The North Landing River watershed has a total phosphorus (TP) Total Maximum Daily Load (TMDL) and the City of Virginia Beach (CVB) has a TP reduction goal of 775.1 pounds per year, as required by Virginia Department of Environmental Quality (DEQ). To help meet these water quality requirements, the CVB tasked AECOM with designing a phosphorus-reduction solution using a filtering Manufacturer Treatment Device (MTD) within the public park located in the Salem Village neighborhood. The proposed design involves installing a diversion structure with a weir in an existing 42-inch stormwater pipe to divert the first inch of runoff to an underground filtering MTD, which then discharges to a downstream wet pond. AECOM collaborated with the CVB to ensure the design met criteria such as feasibility, phosphorus removal efficiency, maintenance needs, life cycle costs, and overall cost-effectiveness. This collaboration aimed to improve water quality and benefit local waterways. One significant advantage of underground filtering MTDs is their small footprint, allowing built-out communities to maximize available surface space for outdoor recreational uses. Although housing the MTD and its components underground allows for valuable surface space to be preserved, MTD construction is often limited to tight working spaces within urban environments and considerations to vibrational impacts, geotechnical investigations, traffic management and work access in the design phase must be carefully planned and measured. A key challenge identified when planning the Salem Villages MTD system was its contributing drainage area and large diameter stormwater main that needed to be intersected. A high water table and flat topography both impacted the design and performance of the MTD. A diversion structure that was able to direct the one-inch storm to the filtering MTD while not increasing the hydraulic grade line in the upstream system was a critical design component. This project aims to demonstrate a composed approach to the design of a filtering MTD to meet phosphorous reduction goals for the Salem Village neighborhood and identify the considerations necessary to ensure long-term performance of the system.
Author Bio
Thomas Bio: Graduated from Old Dominion University in 2022, I am a civil engineer specializing in water infrastructure solutions within AECOM's water group in Virginia Beach. Since joining the company, Thomas worked on a diverse range of projects, including infrastructure advancements at wastewater treatment plants, stormwater management design, asset management solutions, & flood mitigation strategies. Outside of work, Thomas is an avid sports fan and enjoy gardening as a hobby. Kerstin Bio: Project Manager at AECOM, specializing in Stormwater Design and Program Management. With a strong background in managing complex projects, Kerstin has consistently delivered innovative solutions to enhance stormwater infrastructure and sustainability. Outside of work, she is dedicated to supporting military veterans as they transition to civilian life. This passion for helping others underscores Kerstin's commitment to making a positive impact both professionally and personally.
