Overview
An anomaly was discovered during a routine inspection on a natural gas pipeline located in the Stones River. Permanent repair was required restore pipeline integrity.

Scope of Work
Ballard was tasked with locating a natural gas line pipe, thirty inches in diameter, through the bottom soils which included rock, clays and silts and uncovering it for anomaly examination.

Innovative Solutions
The owner of the pipe was not confident that the pipe could be located accurately enough to allow for the use of the required excavation equipment or the installation of a cofferdam. Ballard had special equipment shipped in from Australia to help locate not only the pipe but the exact location of the anomalies which do not manifest as surface defects. Ballard then prepared to provide a dry environment for the pipe to be repaired. These solutions included designing a cofferdam for the middle of a reservoir and separately use a special habitat to clamp the pipe and allow the water within the habitat to be removed. In the end, Ballard worked with the owner who decided that a Plidco clamp could be installed under water in a shorter period and that they would continue to work with regulators to make this solution permanent. Ballard installed a full depth turbidity curtain which completely enclosed the area around the pipe anomaly. The soil was then excavated around the pipe using both mechanical means and suction dredging. An extensive amount of hand labor was also required. Despite poor visibility, Ballard was able to locate the anomalies and remove all the pipe coating to a white finish in preparation for the installation of the clamp. The 2,500-pound clamp was then lowered into position using a special barge layout that included a gantry crane for finite control of the process. The clamp was installed per manufacture’s recommendations and the exposed portions of the pipe were re-coated for protection from the environment. After all testing requirements had been accomplished, the pipe was buried, and demobilization commenced.

Results
Ballard worked under the constraints of the applicable environmental permits from the United States Army Corps of Engineers (USACE), U.S. Fish and Wildlife Service (USFWS), and local regulators such as Aquatic Resource Alteration Permit (ARAP) for boat traffic control and turbidity without incident. The project was completed safely and with little to no interruption of the operation of the pipeline.