Some concerns were expressed about the potential impact of seismic mapping scheduled to take place next month in the Harmar district and portions of downtown Marietta during Wednesday's meeting of Marietta City Council's streets and transportation committee.
Precision Geophysical, Inc., a seismic mapping firm from Millersburg, is slated to pass through town with two vibration-generating trucks between July 1 and 3.
The vehicles will be driven slowly along local streets and at regular intervals a large vibrating metal disk will be lowered to the road surface from the trucks' undercarriages. The disk creates underground seismic waves that are used to develop 2- and 3-dimensional maps exploring rock and shale formations for oil and gas companies.
The mapping route runs north along Ohio 7 into the Harmar area, turns right onto Lord Street, then travels through Barber Avenue, Elm Street and Harmar Street before crossing the Putnam Bridge onto Putnam Street.
The trucks will move along Putnam to Seventh street, then travel south to Pike Street and back onto Ohio 7 north past the city limits. "One of my constituents called and was concerned about the historic wall and drainage ditch along Lord Street," said Councilman Tom Vukovic, D-4th Ward.
The resident noted the aged wall is not in stable condition and was worried that vibrations generated during the seismic process could damage the structure.
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"There is also some concern for basements, foundations and storm sewers in the Harmar area," Vukovic said. "We have antiquated water and sewer lines in Harmar, and we're concerned the vibrations could damage those lines. And we may not see any effects immediately, but damages could show up later on."
He asked why the seismic mapping route was passing through the Harmar district.
Precision Geophysical representative Bill Peterson said the route is pre-determined by the oil and gas companies who contract for his company's services.
"They're recording data up to three miles away and down to 10,000 feet to locate underground formations, and how thick the layers of rock are beneath the surface," he said. "The seismic process is the tool we use to help map those areas."
Peterson said vibrations generated by the company's equipment would be "low-force" and would not be operating less than 100 feet from area homes.
"There's really nothing to worry about," he said, adding that, although it's not required, the company would also be carrying $9 million of liability insurance in case any damage should occur to property or infrastructure.
"But I've never seen any problems with water or sewer lines in any of the cities we've mapped," Peterson said.
A similar seismic mapping process during July 2012, by Tidelands Geological Company (TGC) of Plano, Texas, was reportedly felt in homes and businesses along their route through Marietta. But Peterson said the mapping that will occur July 1-3 will not use high force vibrations and will be much less intrusive.
Eric Lambert, project manager with the city engineering office, said residents along the Precision Geophysical mapping route who are concerned about potential property damage could create documentation by taking time-stamped photos or videos of their properties before the seismic mapping process occurs.
He said if any damage claims are filed in relation to the seismic process the photographs or video footage could help determine whether the damage actually occurred.
"We have to be fair to both sides," Lambert said. "And the more documentation people can provide the better."
Vukovic asked Lambert to make sure to photograph the wall and drainage structures along Lord Street for the city.
Although Peterson said the vibrations would not be high enough to shake houses or foundations, Lambert said if anyone is concerned they should move any heirlooms off of shelves or walls when the seismic mapping units pass through their neighborhoods.
Vukovic also asked Peterson for a list of communities where Precision Geophysical, Inc. had recently performed similar seismic mapping.
Peterson said he did not have that information Wednesday, but would obtain the list and provide it to the committee.
The vibrations created last July by vehicles from were likened to an earthquake by some taken by surprise by the large trucks moving through.