- ENGINEERING INFO
- CASE STUDIES
When the Virginia Department of Transportation (VDOT) finalized plans for the Nimmo Parkway Extension in Virginia Beach, it was clear that the on-site water line would need to be relocated. Most of the line would be suitable for typical open-cut construction, but a 2,000 LF horizontal directional drill (HDD) crossing under a creek and wetlands would be necessary. Originally designed several years earlier for 20-inch HDPE (with a 16-inch ID), the City of Virginia Beach and VDOT's utility design firm, Michael Baker International, decided to add an option for 16-inch Fusible C-905® pipe to match the diameter of the connecting pipe on either side. After the bid, they also decided a second HDD of 680 LF would be better suited to cross another smaller creek.
The drilling subcontractor, Atlantic Boring, teamed with Spring & Associates for the longer, 2,000 LF shot, and completed the work on the Friday just before Hurricane Sandy hit the Tidewater area during the weekend of October 27th and 28th. It was two weeks before Atlantic Boring could return to hydrotest the pipe to 160 psi.
The second, shorter drill proved, ironically, to be the more difficult of the two. Wesley Dunks, owner of Atlantic Boring, said: "Soil borings for the shorter drill shot missed an old roadbed that crossed the bore path about 200 feet from the exit at a depth of four or five feet. The material in the roadbed was a non-cohesive gravel base that collapsed into the bore just as we were pulling the pipe through that location. Unfortunately, nothing could be done, other than dig it up and install the remainder of the Fusible PVC® pipe by open-cut methods." Once the decision was approved by the authorities, it became a matter of fighting groundwater and trenching 25 feet at a time while the pipe was fused in place.
|Pipeline Details and Project Summary|
|Project:||Nimmo Parkway Extension|
|Location:||Virginia Beach, VA|
|Length:||2,000 LF & 680 LF|
|Pipe Size:||16-inch DR21 DIPS OD|
|Owner:||City of Virginia Beach|
|Engineer:||Michael Baker International|
|Contactor:||Waterfront Marine with Atlantic Boring, Inc.|
After all the challenges wrought by jobsite condition and Mother Nature, the City was pleased with the result and glad the contractors persevered. Said Design and Construction Manager, Rich Nettleton of Virginia Beach, "Both PE and Fusible PVC® pipe were allowed, but the City chose Fusible PVC® pipe because it offers 'bolt up' capabilities to ductile iron pipe and, in addition, is unaffected by aggressive soils."