CCN Newsletter - Autumn 2001 - Page 10

JULY—SEPTEMBER 2001: During Columbia's typical hot steamy summer, construction crews installed new water mains along the hilly, tree-lined terrain of Makeway Drive and Westbury Drive. Several streets in Earlewood, an expansive North Columbia community of over 2,000 residents, are scheduled for waterline upgrading. Oconee Street is next (October 2001), followed by Keenan and adjacent streets just off scenic Sunset Drive. The City's new waterline upgrading project involves a "horizontal directional drilling" technique.

Photos by Katherine J. Trimnal, CCN Newsletter

CITY ADOPTS STATE-OF-THE-ART WATERLINE UPGRADING METHOD
HORIZONTAL DIRECTIONAL DRILLING

Construction crewmen worked throughout the long, hot summer on Earlewood streets, replacing corroded insufficient 1-1/2" waterlines with new-on-the-market 6" and 8" pipes. The pressure rated High Density Polyethylene (HDPE) pipes are an integral part of the city's preferred waterline replacement system—horizontal directional drilling. Gone are the days of digging 4-foot deep trenches across residents' driveways and yards, while dodging drivers along busy neighborhood streets. The new non-invasive, subterranean drilling project being tested in the Earlewood Community involved Makeway Drive, Westbury Drive (both now completed) and Oconee Street (scheduled for October 2001). The cost of the capital improvement project for the three streets: $306,000. The next directional drilling waterline replacement is scheduled for Keenan Drive and streets around "the loop" in Earlewood, between Sunset Drive and Earlewood Park. The high-tech Earlewood Neighborhood waterline replacement project was contracted through the City of Columbia Engineering Department to GH Smith Construction Company and directional boring subcontractor, Bore-Tek.

The following technical information on directional drilling was, provided by John Hornsby, Civil Engineer I, City of Columbia Department of Engineering — Tel (803) 733-8232:

During the design phase of this (Earlewood) project, the City set out to find an alternative to the conventional open cut method of installing water lines. The open cut method involves excavation of a48" deep longitudinal trench to install the pipe. Because this method is highly disruptive and there is limited space for construction along the effected streets, the City of Columbia decided to utilize a new technology called directional drilling.

The basic process of directional drilling involves boring a pilot hole in the desired location for the water line with precisely guided rods. These rods are then used to enlarge the hole and pull the pipe through. The accuracy of directional drilling allows for the pipe to be put in without disturbing existing utilities or surface structures. Because the drilling equipment can reach long distances, excavation is limited mainly to the ends of the boring runs and service connections.

In addition to the new installation method, the City is using a new type of pipe; pressure rated High Density Polyethylene, or HDPE. The new strength and flexibility of this pipe is conducive to directional drilling. Because sections of the pipe are fusion welded together, the joints are as strong as the pipe itself. This makes it highly resistant to leakage and joint failure.

For the Earlewood project, directional drilling has allowed the City to install waterlines in places, such as under trees and roads, which were not accessible by standard installation methods. Reducing the amount of traffic hazards and open trenches has maximized safety of residents during construction and minimized disturbance to the residents."

ACKNOWLEDGEMENT: THANKS TO PHONG HOANG, CITY OF COLUMBIA ENGINEERING DEPARTMENT, FOR HIS CREATIVITY, VISION AND ASSISTANCE IN DEVELOPING THE NEW LOGO & DESIGN OF THE CCN NEWSLETTER.