Milestone Reservoir

The next phase of Loudoun Water’s Potomac Water Supply Program is to convert the first of four Luck Stone quarries into a raw water storage facility. Milestone Reservoir will sit on a 20-acre site north of the Washington & Old Dominion (W&OD) trail and east of Goose Creek. The Reservoir will provide one billion gallons of raw water storage capacity to supply the Trap Rock Water Treatment Facility (TRWTF) during periods of low flow in the Potomac River. The Reservoir will be filled with raw water from the Potomac River. The project is expected to be complete in 2028. Loudoun Water is utilizing an alternative project delivery method – Construction Management at Risk (CMAR) – for this project. Clark Construction Group, LLC has been selected to serve as the CMAR. The construction contract was awarded in the fourth quarter of 2023 and work is now underway.

The pump station, used to pump water from the Reservoir to the TRWTF, will be situated on a parcel at the confluence of Sycolin Creek and Goose Creek. Formerly owned by NOVA Parks, Loudoun Water acquired this site in conjunction with our partnership that prioritizes our shared community-oriented and public service missions. NOVA Parks will retain a recreational easement, intended to continue public access opportunities in the areas outside of the critical infrastructure uses related to Loudoun Water’s operations. The project includes a 40 MGD deep shaft pump station with intake tunnels connecting the shaft and quarry, raw water transmission lines, a pump station building, and miscellaneous improvements such as fencing, access roads, stormwater facilities, surface site improvements, and rock stabilization. Project details include the following:

Pump Station
  • One 270-foot deep, 30-foot finished inside diameter pump shaft
  • Three 10-foot diameter intake tunnels, 700 to 850 feet in length
  • 40 MGD pump station
Raw Water Transmission Mains
  • 36-inch and 42-inch transmission mains
Other Improvements
  • 30-foot diameter tunnel plug between quarry reservoir and an active quarry
  • Stormwater facilities
  • Rock slope stabilization
  • Water and sewer connections
  • Surface site improvements

Community Impacts (The W&OD Trail will NOT be closed for this project)

Crossing of the W&OD Trail by Contractor: 
  • Contractor will have daily crossings of the W&OD Trail starting in December 2023 until installation of a temporary culvert is completed by March 2024.
  • Contractor may require crossing of the trail in Q3 2024 to facilitate work at the bypass vault. 
  • Contractor will be installing raw water pipelines across the trail and will be using a phased trail relocation approach to maintain access for users to the trail. Work is anticipated from Q4 2024 through Q2 2025.
  • Contractor will use signage, flaggers and orange barrels for point of entry/exit.
Clearing & Grubbing Two Creek Trail Area (TCTA) Site:
  • Contractor will be clearing trees on the TCTA Site from December 2023 to February 2024. Impacts to trail users are not anticipated but work may be visible from the trail.
Construction Blasting and Noise Impacts:
  • Contractor will be blasting and excavating the TCTA site from Q3 2024 to Q4 2024.
  • Other blasting will occur throughout construction but will be further underground with limited (if any) impact to the public.
  • Contractor will stage flaggers at Cochran Mill by STAR Concrete and at the bridge over Goose Creek to hold pedestrian traffic before blasting goes off.
  • Contractor will make sure the trail is clear between the two points of blockage, once the All clear is signaled, Clark will then open the trail for pedestrians.
Project Status: 
In Construction