Blasting may be needed to install Rock Springs sewer line

Matthew Lane • Jul 22, 2007 at 12:00 AM

KINGSPORT - Kingsport officials have notified the Tennessee Department of Environment and Conservation blasting may be needed to install a sewer line to a new 330-home development in the Rock Springs community.

Kingsport residents Danny and Darin Karst, members of a local group of developers, have begun site work on a 161-acre development off Rock Springs Road called The Edinburgh. The development aims to include around 330 one- and two-story homes in a variety of ways (single-family, patio, townhouses and condos), in various sizes (2,500 to 3,500 square feet) and in different price ranges (from $250,000 to $350,000).

Danny Karst said 12 of the first 27 lots in the development have sold. Two homes are under construction, with four more beginning over the next three weeks. Water and sewer have been installed to the first phase along with 2,600 linear feet of roadway.

The Karsts donated 14 acres of the land to Kingsport City Schools to be used as the site of a new 500-student elementary school. Preliminary plans also call for around 1.5 acres of commercial space at the front of the development.

Last year Kingsport annexed the property with plans to install $2.1 million in water line upgrades and new sewer line to the development. Because of this work, the city created a five-year annexation plan to bring in property leading up to the development and the surrounding area.

Kingsport intends to install 9,015 feet of gravity sewer line parallel to Rock Springs Branch, which is a method used by cities and contractors across the county, said City Engineer Hank Clabaugh.

"The policy is to follow a creek bed. We've got to stay near the stream to keep that gravity flow and without using pump stations," Clabaugh said. "It's done like this across the country."

Kingsport filed notice of the sewer line work April 5. However, after reviewing the land around the stream, Clabaugh said the city determined blasting may be needed to install the sewer line. The preferred method would be hammering and/or open cut excavation, but the application states blasting would be used in situations deemed necessary.

"It's a standard construction process. You need to use blasting when you get in solid rock. For water lines, they're typically around 3 foot deep. A lot of times you can put a hammer on the end of a backhoe and beat the rock," Clabaugh said. "On a sewer line, sometimes you get 10 feet deep, and that's when blasting is needed."

Clabaugh said the blasting should not have an impact on the stream or the nearby houses, and residents would not feel the blast, but they would be able to hear it. If blasting is needed, a contractor would measure how far away the nearest house would be, then size the amount of powder based on the depth of the sewer line and the distance to the house.

"Initially we thought we might hammer it, but after we talked to more contractors and since we're on a tight deadline to get sewer out to the school, they said if we hammer it, it would take three times as long and cost 10 times as much," Clabaugh said. "If we get in the creek with a backhoe and start hammering at rock, sitting in the stream for days ... that's not environmentally friendly having a backhoe leaking oil into the stream."

The TDEC application also states the sewer line would cross Rock Springs Branch and its tributaries 18 times and be encased with concrete and have a clay cap and riprap on top of the concrete.

"Any portion of the stream bank disturbed for any reason other than crossing the creek with the sewer line would be stabilized with grass matting, coconut rolls and other natural stabilizers," the application states.

"This project is nothing out of the ordinary. I can list project after project where any trunk line is laid right down the creek and blasting has been used," Clabaugh said. "That's just the way it is."

The revised permit ran in the Times-News on July 6, and persons have 30 days from that date to submit written comments or request a public hearing of TDEC.

Clabaugh said construction on the sewer line could start as soon as mid- to late September, but more likely in October.

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