The frequency and severity of storms impacting coastal Virginia have increased significantly in recent years. This has created a chronic flooding problem in many areas along the Chesapeake Bay, the largest natural estuary in the U.S., particularly in Virginia Beach.
Of the 16 coastal storms of record in Virginia Beach, 10 have occurred in the last 20 years. During one six-week period in 2016, Virginia Beach experienced 35-inches of rainfall from three storms, or more than two-thirds of the region’s average annual rainfall.
In an effort to prepare the community against the threat of extreme weather, the City of Virginia Beach created the Eastern Shore Drive Drainage Improvements Project. As part of the project team, WSP USA is providing multiple services, including hydrologic and hydraulic modeling, infrastructure improvement alternatives evaluation, preliminary through final design, preparation of construction bid documents, environmental permitting, public participation services, and construction support.
“WSP is closely evaluating historical and projected trends in rainfall precipitation, sea level rise and extreme weather to anticipate future conditions and develop a flexible, innovative, comprehensive and future-ready infrastructure improvement plan,” said Glenn Bottomley, who is serving as WSP’s project manager for the first phase of the Eastern Shore Drive Drainage Improvements. “This plan will require a $40 million multi-phased construction program that integrates the city budgeting constraints and prioritizes the phases that provide the greatest degree of flood protection and benefits.”
“The project will provide a safer environment for citizens of Virginia Beach and an enhanced quality of life by protecting against extreme weather impacts,” added Tom Gay, lead project engineer for WSP. “The resilient infrastructure improvements will also allow the community to quickly recover from significant storm events that are greater than the design storm level of protection.”
The recently installed automated tide gates, constructed under the first phase of the project, prevented structural flooding during a storm in 2019.
The project watershed is located at the confluence of the Atlantic Ocean, Chesapeake Bay and Lynnhaven River. The proximity to this dynamic coastal environment results in frequent flooding with structural damage due to elevated tides from tropical storms, hurricanes and nor’easters.
“The flat, low-lying topography typically associated with areas along the Southeast and Mid-Atlantic United States coasts can worsen flooding due to heavy rainfall from major storm events and intense summer thunderstorms,” Bottomley said. “Flooding damage occurs from tidal flooding alone and combined rainfall and tidal events further compound the flooding problem.”
In addition, rising sea levels and increased precipitation have exacerbated flooding issues and observed trends indicate that sea levels will continue to increase into the future. Significant emphasis is being placed on protection of homes, businesses, city facilities and roads against flood waters from rainfall and tidal events, as well as quicker recovery following significantly higher than design storms.
By addressing anticipated risks associated with sea level rise and increased precipitation, WSP is helping create a community that is Future Ready™—thinking beyond the conventional to prepare for the changes and challenges the world will face, and improving the overall quality of life through information, thoughtful solutions, and approaches that will have a positive impact on the environment.
The objectives of the project’s system of innovative resilient infrastructure improvements are to provide:
- protection against adverse impacts of extreme weather,
- protection against sea level rise and increased precipitation,
- a safe environment for citizens and staff,
- an enhanced quality of life,
- protection against adverse economic impacts,
- protection against property and asset damage, and
- stakeholder coordination and consensus building.
The project is well on its way towards making an impact on the community. The preliminary alternatives evaluation phase has been completed and recommendations for construction phasing were developed. In addition, the first phase of construction is complete and has provided automated tide gates to protect the community against elevated storm tides. Future phasing will provide pump stations to protect against rainfall.
This project is advancing a standard for the design of future stormwater pump stations and automated tide protection in Virginia Beach.
“Pump stations are being designed to be consistent with the city’s preferred facility configuration, which WSP helped establish by developing design guidelines under a separate effort,” Bottomley said.
The innovative system includes three interconnected stormwater pump stations and allows for the normal tidal ebb and flow in the watershed’s main drainage canal, providing bypass pumping for rainfall runoff around the tide gates when closed. This prevents flooding from rainfall runoff being trapped upstream from the closed tide gate.
The gate closure-pumped bypass concept provides sustainable protection against future sea level rise. Elevating roads are also part of the comprehensive plan to protect the community against critical flooding elevations.
Construction is currently under way for the second phase, which includes storm drain collection system improvements and tide control in various locations throughout the project drainage area. Final detailed design is also progressing for three of the five overall project sections.
WSP collaborated with city officials to refine their design policies and the configuration of protection systems for resilient infrastructure projects. This included refining design criteria, applying hydraulic modeling techniques, and taking the lead on establishing pump station system guidelines.
“WSP collaborated with multiple adjacent projects and took the lead in coordinating stormwater resilience protection for the overall watershed,” Gay said. “We took the lead and provided peer review of other consultants' proposed projects in the area for the overall watershed.”
Communicating the engineering evaluation and the preferred alternatives with the residents, businesses, elected officials, and civic groups also required close collaboration.
Some of the most extensive collaboration occurred with multiple city departments, especially with the siting of three proposed stormwater pump station and tide prevention facilities in a developed urban area, including a pump station site located at a city park.
“This required an expansive alternatives analysis and multiple coordination meetings with the Parks & Recreation Department to develop a pump station facility layout that will minimize impacts on the city park and address enhanced aesthetics to integrate the facility into the park surroundings,” Gay said.
Setting an Example
The work WSP is doing for the Virginia Coastal Resilience Project was a featured topic of papers that Bottomley and Gay prepared for two recent water and environment events hosted by the American Society of Civil Engineers (ASCE).
In planned presentations to the Environmental and Water Resources Institute World Environmental & Water Resources Congress, Bottomley discussed “Smart Stormwater Pump Station Systems for Coastal Resilience in Virginia.” At the Environmental and Water Resources Institute Watershed Management Conference, Gay’s paper discussed “Hydraulic Modeling and Alternatives Evaluation for Storm Drainage Improvements in a Dynamic Coastal Environment.”
“It is rewarding to be able to develop solutions that will protect residences and businesses from flooding and allow them to recover quickly after significant storm events,” Gay said. “It has been a privilege and a challenge to be involved in this type of work in one of the areas that is more heavily impacted by sea level rise.”
“It has been satisfying to be a part of Virginia Beach’s efforts to identify the threats of extreme weather and sea level rise and establish an implementation plan that will allow the city to face the resiliency challenges of the future,” Bottomley added. “In conjunction with my last 20 years of service to Virginia Beach, it is rewarding to continue to be a trusted advisor to the city and to strive to establish a higher quality of life for its citizens and bring the WSP vision of Future Ready to our client and the community.”