Beaverdam Creek Dam Modifications & Transfer Pump Station

Key Accomplishments

Johnston Construction Company

• The overall project included phased demolition and reconstruction of the existing spillway, construction of reinforced concrete spillway walls, slabs, a labyrinth weir, spillway chute and stilling basin, outlet works improvements, dam embankment modifications, and construction of a new transfer pump station.
• JCC performed concrete construction associated with approximately 20.45 cubic yards of concrete weir boxes and approximately 404.38 cubic yards of conventional concrete for small structures, along with work associated with the valve and meter chamber, outlet extension, control tower, and transfer pump station.
• JCC completed specialized control tower concrete restoration consisting of approximately 200 SF of Type 1 repairs, 50 SF of Type 2 repairs, 1,018 SF of Type 3 repairs, 100 LF of Type 4 repairs, and 100 LF of Type 5 repairs, together with pre-repair inspection and repair documentation.
• The work required extensive coordination with Loudoun Water, Gannett Fleming, Thalle Construction Company, and other project trades through multiple water-diversion phases while maintaining the reservoir’s water-supply function and protecting the existing dam, reservoir, and surrounding waterways.
• Johnston Construction Company completed a major civil construction package for the Beaverdam Creek Dam Modifications and Transfer Pump Station project in Loudoun County, Virginia. The project was undertaken for Loudoun Water and designed by Gannett Fleming, Inc., with Thalle Construction Company serving as the Prime Contractor. The existing Beaverdam Creek Dam is an approximately 55-foot-high, 1,176-foot-long earth embankment supporting Beaverdam Creek Reservoir.
• JCC’s subcontracted work included concrete construction for weir boxes and small structures, valve and meter chamber equipment, outlet extension equipment, control tower modifications, transfer pump station equipment, and concrete repair work. The scope included approximately 20.45 cubic yards of concrete work associated with weir boxes and approximately 404.38 cubic yards of conventional concrete work associated with small structures.
• JCC also performed work associated with the spillway valve and meter chamber, outlet extension, and transfer pump station. The overall project incorporated a concrete spillway valve and meter chamber with piping, flow-metering equipment, valves and related appurtenances; modifications to the existing outlet works; and a new transfer pump station consisting of a concrete sump with submersible pumps and an attached concrete valve chamber with check valves, isolation valves, instrumentation, and controls.
• Construction required careful planning because Beaverdam Creek Reservoir remained in service for water-supply purposes throughout the project. Work areas extended upstream of, within, and downstream of the existing dam spillway. Multiple phases of temporary water diversion, cofferdam construction, dewatering, and flood-protection measures were required so construction could proceed without compromising dam safety or adversely affecting Beaverdam Creek Reservoir, Beaverdam Creek, or Goose Creek.
• The project also required coordination of multiple trades and subcontractors throughout the various diversion phases because the entire dam could not be made available for construction at one time. JCC coordinated its concrete, control tower, outlet works, and transfer pump station activities with the overall phased construction program while existing reservoir operations continued.
• The Project Was Completed On 27th August, 2019

Concrete Services Division

• Concrete Services Division, LLC performed the concrete construction package supporting Johnston Construction Company’s work on the Beaverdam Creek Dam Modifications and Transfer Pump Station project in Loudoun County, Virginia.
• CSD’s scope included concrete forming, placement, finishing, curing, accessory labor, dowel placement, and related concrete construction for the spillway valve and meter chamber, transfer pump station, outlet works extension, weir boxes, electrical building, pipe supports, and control tower improvements.
• Major structural concrete work included slabs, walls, top slabs, footings, wing walls, beams, baffle walls, pipe supports, foundations, and other components required for the project’s new water-control and pumping structures.
• CSD performed concrete work for the West and East Weir Boxes, the electrical building footing, foundation and slab, concrete pipe supports, backfill concrete beneath structures, and a new control tower pipe pad.
• CSD completed specialized concrete restoration within the existing control tower, including pre-repair concrete inspection and approximately 200 SF of Type 1 repairs, 50 SF of Type 2 repairs, 1,018 SF of Type 3 repairs, 100 LF of Type 4 repairs, and 100 LF of Type 5 repairs.
• The work was performed as part of a complex dam-modification project requiring phased water diversion and careful coordination while Beaverdam Creek Reservoir remained in service for water-supply purposes throughout construction.
• Concrete Services Division, LLC completed the concrete construction package associated with Johnston Construction Company’s work on the Beaverdam Creek Dam Modifications and Transfer Pump Station project in Loudoun County, Virginia. The project was undertaken for Loudoun Water and designed by Gannett Fleming, Inc., with Thalle Construction Company serving as the Prime Contractor and Johnston Construction Company performing a major civil subcontract package.
• The overall project involved extensive modifications to the existing dam and reservoir infrastructure. Improvements included demolition and reconstruction of portions of the spillway; new reinforced concrete spillway walls, slabs, labyrinth weir, chute and stilling basin; construction of a new spillway valve and meter chamber; rehabilitation of the existing control tower and outlet works; dam embankment improvements; and construction of a new transfer pump station and electrical building.
• CSD’s concrete work supported numerous structures throughout the project. Its scope included forming and concrete-placement activities for the spillway valve and meter chamber, including the sump slab, structural slabs, walls, top slab and pipe supports. Concrete construction associated with the transfer pump station and outlet works extension included structural walls, slabs, footings, wing walls, beams, baffle walls and other concrete components identified in the subcontract.
• Additional concrete work included the East and West Weir Boxes, pipe supports, backfill concrete beneath structures, and construction of the electrical building footing, foundation and slab. CSD’s subcontract included the labor and equipment associated with formwork installation and stripping, concrete placement and finishing, curing, concrete accessories and joint work, winter-protection labor, and dowel placement.
• The Project Was Completed On 27th August, 2019