SLIPPERY ROCK — The state’s current Marcellus Shale natural gas boom could provide many opportunities, said an industry executive.

John Applegath, vice president of the southern Marcellus Shale division of Range Resources, said Tuesday at Slippery Rock University that shale gas development in the decade has given the U.S. a 100 year natural gas supply.

“Shale is a big game changer,” Applegath said.

The Barnett Shale in Texas currently provides 5 percent of natural gas in the U.S. Applegath said the Marcellus Shale is 10 times larger than the Barnett Shale.

“That would imply that 50 percent of the U.S. natural gas could come out of the Marcellus Shale,” Applegath said.

In addition to the Marcellus Shale in Western Pennsylvania, Applegath said there also is the Upper Devonian Shale and the Utica Shale. He said that all three formations could be used at the same time.

Although drilling on well pads can be a large operation, once the drilling is done, well pads have small footprints.

“Very low impact once construction is done,” Applegath said.

Once initial wells are drilled, Applegath said, “infield” wells could be drilled later to develop more gas.

“There’s going to be activity here ... for nearly 50, 60, 70, 80 years,” Applegath said.

Applegath said the Marcellus Shale boom has contributed to a lot of job growth in the region, noting that Washington County had the third highest job growth and Butler County had the seventh in the U.S. in 2011.

He said that one well has 410 workers, with 150 different job types. Additionally, seven out of 10 hires are state residents.

The average salary for a worker in the industry is $76,036. He said the average salary has increased 16 percent per year for a few years.

“Jobs in this industry are well paying,” Applegath said.

He said job growth affects both drilling companies and ancillary industries.

Despite the growth potential, there are some concerns, particularly related to water contamination.

Applegath said that Range tries to minimize water well contamination by building a well casing that uses 3 million pounds of steel and concrete.

He said that all of the gas wells in Western Pennsylvania use 19.2 million gallons of water per day. However, mining activity in the area uses 182 million gallons per day and power generation uses 5,930 million gallons per day.

“The Marcellus Shale doesn’t really use that much water,” Applegath said.

He said the fluid used during hydraulic fracturing, a process which releases gas from shale rock, is safe. It is 99.9 percent sand and water and 0.1 percent additives, mostly friction reducers and anti-bacterials.

With so many people worried about the makeup of the fluid, Applegath said, Range was the first company to post on its website what the fluid contains.

He said that Range takes all of the water that returns to the surface after fracking, stores in steel containers and reuses it at other well sites.

“This is a fantastic reservoir,” Applegath said.

Some shale formations do not respond well when fracking fluid is reused. However, Applegath said the tests on the Marcellus Shale have shown no difference between using fresh water and reused fluid.

Applegath said, with all of the concerns, it is important for drilling to be done properly and for companies to take care of the environment and be up front with the public.

“We have to make sure we are doing things right, even if it costs us more,” Applegath said.