WID Bulletin June 2002

WID Bulletin #201, June 2002
Tripps Run Bridge

VDOT's bridge construction contractor Moore Brothers Company, Incorporated is now hard at work tearing out the old causeway and temporary bridge and initiating construction of a new 100 foot span.

Contractor, subcontractor and WID staff are working together to speed the process and re-open Potterton Drive to traffic which is currently being inconvenienced by a temporary detour. Moore Brothers Vice President for Operations Richard McDonough has stated: "Our primary objective is to build the bridge and re-open the road." Thereafter, the old floating debris control boom will be replaced by the new debris deflector system and the new Tripps Run channel to the bridge will be excavated and stream banks stabilized.

Already the temporary bridge planking has been salvaged and the old stream channel culverts are being removed to give Tripps Run an unobstructed channel to prevent flooding during the construction period. A turbidity curtain has been installed below the project to contain sediment and debris during possible future storms.

WID's primary role is to be supportive by providing temporary storage and miscellaneous local help to be followed later by certain construction responsibilities in connection with the debris deflector.

The bridge will be a steel beam supported paved two-lane roadway over one hundred feet long with a center support. It will be somewhat higher than the original Causeway. It will have a pedestrian walkway on each side. The appearance will be neater since the entire Causeway will be removed including the floating debris boom. The incoming stream will be wider and will appear to be an extension of the lake.

The debris deflector will be farther upstream. It will divert storm-driven debris to a stream-side pickup area which will be cleaned out after major storms. Most existing tree screening will be preserved and opportunities for new tree and shrub plantings will be apparent after completion of construction.

The new bridge will pass a 5-year storm event of 2,900 cubic feet per second without road overtopping which is nearly a tenfold increase in the flow capacity of the old Causeway. Flood levels upstream of Potterton Drive will be reduced by about 3 feet. The Fairfax County Department of Public Works and Environmental Services has agreed to maintain the debris deflector system, responding to requests from WID.