Seismic surveys to begin in Dunbar Township in autumn

| Saturday, March 9, 2013, 12:01 a.m.

Seismic surveys will begin in autumn in Dunbar Township to determine the best locations for Marcellus shale gas drilling operations.

Dunbar Township supervisors told residents on Thursday night that testing will begin in October to allow Chevron to select drilling sites.

McDonald Land Services will send letters to property owners who agreed to the surveys, notifying them of the procedures.

The survey will take place in six phases in mid-October until the survey is complete, according to a letter from McDonald Land Services.

“Activity over the entire survey may last over many months,” the letter stated.

The letter explained what residents can expect.

During the first step, Pathfinder will take an initial access survey to locate all items of interest that will be avoided on each property, including pipelines, wells, natural springs, wetlands, buildings, ponds, etc. Pathfinder will then survey source and receiver locations.

“If allowed by permit and only if necessary, areas with heavy brush will be cleared: however, heavy timber will be untouched,” the letter read.

Surveyors will travel to each property in pickup trucks and will drive between properties in small all-purpose utility vehicles while using GPS and/or other equipment to survey source and receiver locations. Each position will be marked with a numbered wooden lathe, and colored ribbons will be used to mark the path from point to point that the crew will follow. The ribbon flagging serves as a visual aid for navigation of field personnel during operations.

“They will be trying to find the best locations for natural gas drilling,” said Dunbar Township Supervisor Chairman John Tabaj. “That is why the surveys will be done.”

During the third phase, Omni Energy Services will use small rubber-tracked drilling rigs to drill and load sound source holes. The holes will be loaded with a small charge, then back-filled with gravel in accordance with state Department of Environmental Protection regulations.

A third company, CGGVeritas, will complete the fourth through sixth steps, according to the letter.

“Receiver equipment will be delivered by a helicopter via long lines to each location on the properties in fluorescent orange duffel bags, containing geophones and receiver boxes,” the letter stated. “Geophones are listening devices that receive the reflection of the sound signal, storing it in the receiver box.”

The source will be detonated one at a time, creating reflective sound waves. In the event that drilled source holes cannot be used exclusively in an area, it will be necessary to use Vibroseis trucks for source locations. In that case, the trucks will travel along specific roads to introduce the reflective sound waves through a series of vibrations.

Once the operations portion of the project for a permit is concluded, the property will be cleared of any remaining equipment and materials.

“We are committed to conducting this survey safely and with respect for your property,” the letter read.

A permitted agent will be available at 724-439-3500 to address any questions or concerns associated with the seismic survey.

Cindy Ekas is a freelance writer.

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