- ENGINEERING INFO
- CASE STUDIES
The amount of recoverable oil from North Dakota's Williston Basin region continues to exceed expectations. Spanning over 200,000 square miles in North Dakota and Montana, the Bakken formation has created a burgeoning oil industry resulting in an explosion of commercial and residential growth. Cities such as Williston, Watford City, and Ray are facing water infrastructure that is overwhelmed by the increased demand. As the need for water grows quickly, the communities race to address the shortage of supply. While building larger and additional pipelines with conventional open-cut methods is part of the solution, many communities are upgrading the existing infrastructure using trenchless installation techniques.
|Pipeline Details and Project Summary|
|Consulting Eng.:||Interstate Engineering; Williston, ND|
|Contractor:||Lakeshore Toltest; Chicago, IL|
|Distributor/Fusion:||Dakota Supply Group|
|Services:||(formerly Fargo Water); Fargo, ND|
|Pipe Burst Length:||4,880 LF 6" DR18 and 10,000 LF of 8" DR18 Fusible C-900®|
The City of Ray sought to upgrade an undersized and aging 4-inch and 6-inch cast iron (CI) potable water system. The design engineer, Interstate Engineering, evaluated several methods to increase hydraulic capacity while minimizing cost and disruption. Given the influx of out-of-state contractors with varied skillsets, Interstate let the market forces deliver the best value to its client. Accordingly, it bid the project open-cut versus pipe bursting, requiring that the 4-inch and 6-inch CI pipelines be upgraded to 6-inch and 8-inch DR18 AWWA C900 PVC pipe. Contractors had the option to bid PVC for the open-cut and Fusible PVC® pipe or HDPE pipe for the pipe burst.
Nine bids were received. Five contractors selected open-cut, with four selecting pipe bursting. The average bid for open-cut was $2 million. The average bid for pipe bursting was $1.68 million. Hence, pipe bursting saved nearly 20% versus open-cut on an average bid basis. The low bidder, Chicago-based Lakeshore Toltest, bid 30% lower with pipe bursting versus the lowest open-cut option.
Toltest selected 8-inch DR18 Fusible C-900® pipe for the bursting material. The decision took into consideration the savings of the overall installation cost, including the pipe, fittings, and labor. Fusible PVC® pipe utilizes standard, off-the-shelf fittings that contractors and utilities prefer over HDPE fittings. HDPE fittings are typically more expensive special order items that require special training to use.
Construction began in late summer of 2012. Dakota Supply Group (formerly Fargo Water), which has fused over 200,000 LF of Fusible PVC® pipe in North Dakota, completed the fusion services with multiple trips from its North Dakota-based offices. After several add-ons, the pipeline was completed in the summer of 2013.
Interstate Engineering has designed many pipe bursting projects in the same region and is a major proponent of trenchless technology. Lonni Fleck, project engineer, said: "Trenchless technology in Ray allowed the City to replace more water main infrastructure than has ever been performed with the open-cut method. This is important in the western North Dakota market, where construction costs are rising at a higher rate than I've ever seen before."
For additional information, please contact Patrick Laidlaw, P.E. at Underground Solutions at 801-699-2804.