The Pennsylvania Supreme Court has denied an appeal filed by a citizen advocacy group challenging four unconventional natural gas well sites operated by Apex Energy LLC near Pittsburgh, capping a fight that has lasted roughly two years.

In a decision on Tuesday, the high court denied Protect Penn-Trafford’s (PT) petition for allowance of appeal in a one-page order. The group had argued that Apex was barred from storing oil and gas wastewater under Penn Township zoning laws. It also argued that the operations would negatively impact the environment.

The township zoning board approved special exemptions for the sites in 2017, clearing a path for development. However, the advocacy group appealed to the Westmoreland County Court, which upheld the exemptions.

Late last year the Pennsylvania Commonwealth Court found that Protect PT failed to present evidence to support its claims, and with Tuesday’s order, the state Supreme Court won’t review that decision.

The state has issued nearly 50 unconventional drilling permits in Penn Township, about 25 miles southeast of Pittsburgh. Apex, which is headquartered in Wexford outside the city, has sparred with township officials in the past.

In 2016, the township denied the company’s request for a conditional use permit to construct  a multi-well pad, saying in its decision that the company failed to prove that its operations would “not violate the environmental rights of the citizens.”

Facing a lawsuit as state regulators oversee the industry, the township eventually settled and Apex, which operates primarily in southwest Pennsylvania, agreed to special development conditions.