Flat Branch Pond

Flat Branch

We want to be a good neighbor

Over the next year, the City of Manassas will be working to create the Flat Branch Regional Stormwater Pond.  This will be located behind the hospital at the end of Digges Road. The information on this page is in an attempt to keep you informed during this year-long project. Thank you for your patience while we create this new resource for City of Manassas businesses and residents.

If you have a particular concern during this process, please submit this form to the City.  We will respond to you as quickly as possible.  Sign up for future notifications on this project.

Flat Branch Map
Flat Branch Stormwater Pond in progress

How does the Flat Branch Regional Stormwater Pond impact you?

Those living and working in the immediate area of the site will be most impacted by the typical sights, sounds and traffic impacts of construction.  
  • The construction entrance for the project will be located at the end of Digges Road and will be the only entrance for construction traffic in and out of the site.
  • On street parking at the end of Digges Road will be prohibited during the construction period.
  • During the construction, there will be increased congestion on Digges Road and Sudley Road while trucks haul material from clearing and excavating the site. 
  • Construction is limited to from 7 a.m. to 7 p.m. Monday through Saturday, so there will be no loud activity during early morning or evening hours to help minimize the effects on those living near the site.
  • There will be no construction on Federal Holidays.
  • The construction workers and vehicles will not be permitted to park on Digges Road or in the private business parking lots along Digges Road.
  • Dust will be controlled by the City's contractor so as to have minimal impact on you and your business.
  • The City, its contractor and the Hospital will work very closely together to ensure there is little to no impact on the Hospital or its services during construction.

How does this project benefit you?


Modern stormwater management ponds are very important for offsetting the negative impacts of urbanization. Ponds reduce the speed of stormwater runoff before it enters natural channels, preserving the natural features and wildlife in a stream or river. It also helps remove dangerous pollutants which are collected by stormwater as it runs over parking lots, roads, yards and fields. In the City of Manassas, we have four major streams and this project will help protect the Bull Run watershed from sediment and pollutants. 

How does this benefit the City of Manassas?


The City of Manassas follows all state and federal regulations for stormwater.  The Virginia Department of Environmental Quality requires localities to apply for an MS4 Permit.  This permit helps regulate the presence of specific pollutants, like phosphorus and sediment in the major streams across the state. This project also provides enough phosphorus removal to help the City meet its phosphorus goals through 2018 and will go a very long way towards meeting the removal goals through 2023 and into the future.

The project is to construct a retention pond that will serve the Virginia Stormwater Management Program requirements for 70 acres of existing development, including the Hospital and parking lot expansions. Also, the project will serve an additional 230 acres of area within the City limits to credit towards the City of Manassas Stage II Municipal Separate Storm Sewer System (MS4) permit requirements. 

A little History:


The City of Manassas has taken a regional approach to providing stormwater management since the initial Virginia regulations were implemented in the late 1980’s and early 1990’s. As a part of this approach, the City has constructed multiple large stormwater management ponds which serve a large area.  This is instead of requiring every construction project in the City to control stormwater runoff on their site.

This site was originally identified as a potential location for a regional stormwater facility in 1999. When then Hospital began planning the construction of their parking lot expansion, the City and Hospital began to work together to use Hospital property to construct a regional stormwater facility.  This project benefits both NOVANT and the City of Manassas, as well as the residents and businesses of Manassas.