SERVICES: Location of Appurtences • Pipe Dewatering & Cleaning • CCTV Inspection • Design • Bid Coordination • Electromagnetic Inspection • Contract Administration • Construction Inspection
WORK PERFORMED: 2010 – February 2011
Mr. Jack Fitzgerald
(p) 336.747.7309 • firstname.lastname@example.org
Mr. Ron Hargrove, Utilities Director
(p)336.747.7312 • (f) 336.727.8432 • email@example.com
Suite 357, City Hall, 101 North Main Street, Winston-Salem, NC 27101
SCOPE OF WORK
Hydrostructures was retained by the Winston-Salem/Forsyth County Utilities Commission to evaluate the condition of a key raw water main that provides water to the Neilson Water Treatment Plant and the Thomas Water Treatment Plant from both the Yadkin River and Salem Lake. The raw main, which was originally constructed in the late 1940’s, included approximately 54,500 linear feet of 36-inch diameter prestressed concrete cylinder pipe (PCCP) and 9,400 linear feet of 48-inch welded steel pipe. A significant portion the raw main was out of service while the Thomas Water Treatment Plant was being replaced and the Utility had a unique opportunity to inspect and evaluate the pipe and make any necessary repairs without having to take the line out of service. The evaluation portion of the project was completed in several phases. First, crews located and evaluated the condition of all key appurtenances such as access manholes, blow-off assemblies, air release valves, isolation valves, etc. At the same time, areas were identified that needed to be cleared to allow access to the main. The main was dewatered through the access manholes and blow-off assemblies. Next, the pipe was cleaned using a combination jetter/vacuum truck to remove any debris that had accumulated in the pipe. The evaluation included closed circuit television (CCTV) inspection using a robotic camera to identify any visible defects or debris within the pipe, and electromagnetic inspection to determine the location of any broken reinforcing wires within the pipe wall itself. A final report was prepared that identified nearly $900,000 in repairs to the main and appurtenances. Subsequently, Hydrostructures, P.A. was retained to design the recommended repairs. The final project included replacement of approximately 2,600 linear feet of 36-inch PCCP pipe with ductile iron pipe, replacement or repair of 35 air release valve assemblies, installation of 2 new isolation valves, and other associated repairs. To expedite completion, two separate construction contracts were awarded and all needed pipe and materials were procured by the City in advance. The project was bid in the fall of 2010, and construction was completed in February of 2011. Minor challenges included coordinating access to the utility easement through private landowners and coordinating schedules with the construction of a new water treatment plant served by the main.
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