- ENGINEERING INFO
- CASE STUDIES
The beauty and tranquility of the northwest Florida Gulf Beaches has been attracting increasing numbers of vacationers and full-time residents from the all over the world for decades. Along with this welcome influx come increased demands on the utility infrastructure to support the ever-expanding population.
WRP, Inc., a water utility created to jointly serve South Walton Utility Company, Inc. and Destin Water Users, needed to construct a 16-mile water transmission main to deliver 9.2 MGD of water from the northern Rockhill Wellfield to the coastal areas of its service districts. The alignment for this transmission main required traversing multiple creeks, wetlands, a major roadway, several developed areas, and a three-mile sub-aqueous crossing of Choctawhatchee Bay. To accommodate the various pipeline conflicts, horizontal directional drill (HDD) construction was utilized in addition to conventional open-cut and marine trenching.
|Pipeline Details and Project Summary|
|Project:||General Bill Brown Wellfield Water Transmission Main|
|Location:||Freeport/South Walton, FL|
|Length:||16 miles total - 12,000 LF of HDD, 17 bore sections|
|Pipe Size:||30-inch DIPS - 30-inch DR25 DIPS Fusible C-905® PVC for HDD|
|Pressure Test:||150 psi|
|Installation:||Open Cut/HDD/Marine Trench|
|Owner:||WRP, Inc.(South Walton Utility Company, Inc. & Destin Water Users)|
|Engineer:||Polyengineering, Inc., James Brannon, P.E|
|Contractor:||Hemphill Construction, Jackson, MS|
|HDD Contactor:||Gator Boring & Trenching, Inc., Pensacola, FL|
James Brannon, P.E., Polyengineering, Inc., Dothan, AL, Engineer of Record for the project, indicated: "HDD construction was a key component to this pipeline design. Not only did it provide us with a means of accommodating the various alignment obstacles, it also significantly reduced the time required to install the various sections." The base design called for primarily DI pipe material, with Fusible PVC® pipe specified in an HDD section located in the vicinity of gas main anode beds. Fusible PVC® pipe and equivalent ID sized HDPE were also allowed as alternate materials for other HDD sections of the alignment.
After competitively bidding the project in late summer of 2011, Hemphill Construction of Jackson, MS was selected as the successful low bidder. Hemphill's selected alternative bid included 30-inch DR25 DIPS Fusible C-905® PVC pipe for the HDD sections of the project. "The lower total installed cost for pipe material, installation, and fittings associated with the Fusible PVC® pipe contributed to the lower total cost of our alternative bid proposal," commented Ricky Eiland, Utility Division VP with Hemphill Construction.
Construction was started on the project in January of 2012. Gator Boring and Trenching of Pensacola was the HDD subcontractor selected for the project. A total of 17 HDD sections were installed on the project, ranging in length from 400 LF to 2,000 LF. "This project presented many challenges from a HDD perspective. The smaller pipe OD and higher tensile strength of Fusible PVC® pipe helped us to successfully complete all of these bores," remarked Eric Lyons of Gator Boring.
During pressure testing, a key benefit of Fusible PVC® pipe was demonstrated. Relative to other thermoplastic pipe materials, such as HDPE, Fusible PVC® pipe does not require rest periods and additional make-up water to account for expansion. All bore sections were individually pressure tested to 150 psi. "The reduced amount of time required for each pressure test was a definite positive," commented Tim Murrah, Hemphill Construction Project Superintendent.
The entire water transmission main was successfully completed and put into service in the early spring of 2013, ahead of schedule. The application of Fusible PVC® pipe for the HDD sections of this project contributed to the overall project success. "The ability to utilize HDD construction and Fusible PVC® pipe for HDD sections of the project enabled us to accomplish portions of the project that would have been significantly more difficult and expensive with conventional open-cut construction methods," said Alicia Keeter, WRP, Inc. Project Manager. "From the Utility's perspective, we see the additional benefit of the being able to utilize standard DI fittings for connection and maintenance of the system in the future as having tremendous value," she added.
The successful and professional execution of this project was based upon detailed design engineering, cutting edge construction methods, proven pipeline materials, specialized construction expertise, and project management knowledge. The end result was a challenging water transmission main being designed, procured, constructed, and completed on time and within budget.