Expert says gas metering facility would pose little risk in Dallas Twp.

By Sarah Hite shite@timesleader.comStaff Writer

DALLAS TWP. – An expert retained by Chief Gathering LLC for a township zoning hearing Wednesday night said there would be “no effect” on the Dallas School District campus if a pipeline leak occurred at a proposed metering facility to be located within 1,400 feet of the closest school building.

Ali Reza, vice president and principal engineer for Exponent Engineering and Scientific Consulting based in Menlo Park, Calif., testified on behalf of Chief’s application for special exceptions to construct a natural gas metering station on a property located off Hildebrandt Road about 1,300 feet from the district boundary line.

Chief attorneys several months ago retained the expert in fire and explosion risk analysis to provide an overview of the proposed project.

Reza said there are several factors involved in the potential for natural gas flowing from a Chief gathering line through a metering site to the Transco interstate pipeline to leak and potentially damage neighboring structures. He said he was told to determine the risk of damage to the Dallas Middle School, which is the closest structure to the metering station at 1,461 feet, and the Fellowship Free Evangelical Church on Hildebrandt Road, which is about 900 feet away.

Reza said there would be no damage to either structure in the worst-case scenario.

He also said natural gas, which is primarily composed of methane and ethane, needs to maintain a certain percentage of concentration to become combustible. The “flammable cloud” surrounding the proposed metering station would only reach to 567 feet in one of Reza’s calculations.

He said that if all these factors were present and all the pipeline’s safeguards, including automatic shut-down valves, failed, the school and church exceed this distance and would not be damaged should the gas leak be ignited.

Reza said he was not instructed to calculate the risk of nearby houses in the area located on Fairground Road.

He said the area in which the pipeline associated with the metering station would be located fits the description of a class 1 level area, a regulation created by the federal Department of Transportation. A class 1 level, which determines the wall thickness, engineering controls and other aspects of the pipeline, would typically be implemented because there are fewer than 10 occupied structures within 220 yards of the pipeline.

Chief plans to utilize a class 4 level pipeline for the project, the highest federally regulated level.

Reza said he based his calculations on the assumption Chief would implement the highest pipeline integrity management program for its planned metering station, but the program has not yet been determined because the plans have not been approved.

Through negotiations, Chief has agreed to remove aspects of its operation from the site, including an 8,000-gallon underground tank of the flammable odorant mercaptan and a 100-foot communications tower.