The Erie County Water Authority (ECWA) required an expansion of a portion of its transmission main system. The primary objective of the project was to extend an existing 36-inch main over two miles. At a critical point, the pipeline route crossed the North Diversion Channel of Ellicott Creek. This section contained a wetland, a recreational bike path, and extremely poor soil conditions.
Through the design process, horizontal directional drilling (HDD) of a flexible-joint pipeline without a casing pipe was deemed to be the most economical and efficient way to cross the channel. The design team and the ECWA worked together to establish expectations and design construction parameters.
The extent of the directional drill was over 800 feet. Ductile Iron Pipe (DIP) sections for the crossing were connected and strung out on a lubricated polyethylene bedding upstream of the drill hole. The HDD for this project set a world record for distance and length for this type of operation.
Project designers successfully coped with:
- extremely poor geotechnical conditions
- groundwater elevations approximately five feet below ground surface
- installation of casing pipe under two overpasses and adjacent to every structure
- soil conditions that would have corroded the DIP, which necessitated wrapping it with polyethylene
- construction of the entire project within an archaeologically sensitive area
- extensive permitting because of the sensitive environmental conditions.
The entire project was completed more than two months ahead of the original schedule, due in part to the speed of the directional drill procedure for the creek crossing. The final project cost was also lower than the original budget.
The completed transmission main fulfills its role of increasing the stability of the water system in northern Erie County for years to come.
2006 Platinum Award
American Council of Engineering Companies (ACEC) of New York