Elizabeth River Crossing, Section I - Replacement
Norfolk, Virginia

Client: Hampton Roads Sanitation District (HRSD)

Our firm was responsible for the planning, design, and construction administration of a 30-inch diameter replacement force main crossing the Elizabeth River. The project consists of a 1,700-foot horizontal directional drilled (HDD) crossing of the Elizabeth River with a nominal 30-inch diameter high-density polyethylene (HDPE) pipe. On the north side, the HDPE pipe connects to an existing HRSD force main via approximately 900 feet of 30-inch diameter ductile iron pipe along an urban street, which is heavily congested with utilities, in Norfolk's downtown business district. On the south side, the HDPE pipe connects to an existing HRSD force main via approximately 350 feet of 30-inch diameter ductile iron pipe, which crosses property owned by the Virginia Department of Transportation.

The Preliminary Engineering Report identified an alignment for the replacement force main, and recommended installation by horizontal directional drilling. Due to the tight radius of the proposed HDD installation, as dictated by the available entry and exit points and the depth of the existing river channel, high-density polyethylene (HDPE) was selected as the pipeline material, using 36-inch outside diameter SDR 11 pipe. The use of an HDD crossing, compared to a conventional crossing, eliminated potential environmental concerns associated with the disturbance of contaminated river sediments.

The project involved significant other work including the "land" pipe installation and its connection to the existing force main. In particular, the available pipeline corridor on the north side of the river presented challenges with utility conflicts, traffic control, and street closure. The project was separated into three contracts - one for the land installation of pipeline, another for the subaqueous installation, and the last for the tie-in connection to the existing HRSD force main at each end. The total construction cost of the project was approximately $2.1 million.