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In February 2008 a new record was established for the longest single HDD pull of large diameter thermoplastic pipe with the successful pull-in of 4,440 LF of 24" Fusible C-905® pipe under the Stono River near Charleston, SC. The project, completed for St. John's Water Company, followed a mile-long HDD pullin of Underground Solutions 10" Fusible PVC™ pipe that was completed in June 2007 for neighboring Beaufort Jasper Water & Sewer Authority.
Mears Group of Houston, TX performed the drill and pull-in. Anson Construction of Charleston, SC provided support to Underground Solutions, Inc. (UGSI) during pipe fusion, and performed pressure testing and reconnection of the drilled pipe to the open-cut installation. The new potable water pipeline was successfully pressure tested in late February and will be placed into service when the rest of the pipeline is completed in Spring 2008.
UGSI began fusion in mid-December 2007 on the grounds of the Charleston Executive Airport, parallel to the east runway. Prior to commencement of drilling operations, 109 fusion joints were completed with the pipe string staged almost the entire length of the airport runway. Winter wind and rain necessitated the construction of a structure around the McElroy 1648 fusion machine to provide a more controlled environment for the fusion process.
Mears Group mobilized in mid-January and completed swabbing of the borehole on February 13th. Pull-in began at 8:00 a.m. on February 15th and was completed 14 hours later. Upon exiting the bore hole on the far side of the river, the print line on the Fusible PVC™ pipe was still clearly legible.
St. John's Water Company and BP Barber became interested in Fusible PVC™ pipe after visiting the nearby Secession Effluent Force Main project in Beaufort, SC, where a record 5,120 LF of 10" DR 14 FPVC™ pipe was installed in a single pull under the Beaufort River. Following the site visit, 24" Fusible PVC™ pipe was added to the St. John's project specifications as an alternate to 30" DR9 HDPE in recognition of the greater safe pull force and smaller bore hole requirement for Fusible C-905® pipe. Steel pipe was also considered, but was heavier, more expensive, and posed long-term corrosion concerns. Estimated total project savings versus the HDPE base bid were approximately 10%.
Colleen Schild, Engineer for St. John's Water Company, commented: "Of the HDD material options, 24" Fusible PVC™ pipe offered both economic advantages and ease of maintenance for our crews. Our confidence in Underground Solutions and Fusible PVC™ was validated by the successful completion of Division 4."
Neil Smith, Vice President of Mears Group, stated: "Fusible PVC™ pipe is allowing us to establish a new frontier in HDD applications with plastic pipe. UGSI's project management and engineering support helped ensure success."
For additional project information or to arrange a visit to a project site, please contact Gary Shepherd.