COCOLALLA — Do not be alarmed if you hear a noise similar to a jet engine on Wednesday.

TransCanada Corp. will be conducting hydrostatic testing on natural gas pipeline starting at around 2 p.m., according to Selkirk Fire Rescue & EMS.

A hydrostatic test involves removing natural gas from the pipeline and replacing it with water. The pressure in the pipeline is then increased beyond normal daily operating pressure, according to TransCanada. If there is a problem with the pipeline, water will escape and leaks will identify places were the pipeline needs to be repaired or replaced.

The venting location is at Gas Transmission Northwest’s mainline valve located on at the corner of Southside School and Berry Hill roads, Selkirk Fire said in a post to its Facebook page.

The venting stack is, as the crow flies, 1,465 feet from Southside Elementary School.

“Even at that distance, the noise will be very loud,” Selkirk Fire said the social media post.

The hydrostatic test, also known as a blowdown, is expected to last one and half to two hours.

“The hope is to start as soon as school lets out and to finish about 4-5 p.m., before landowners come home after work,” Selkirk Fire said.

TransCanada will verify that the school is vacated and landowners within a half-mile radius of the blowdown location will be notified by mail of the testing.

“The blowdown process is safe but very loud and is consistent with pipeline safety and environmental laws. Natural gas is non-toxic, lighter than air and readily dissipates into the atmosphere. GTN’s goal is to inform and protect the affected public, private landowners and their animals prior to and during the blowdown,” Selkirk Fire said.

Bonner Dispatch will be notified of the testing and they will in turn notify law enforcement, fire districts and other emergency responders. Calls to 911 are expected due to the noise the testing generates.

“A temporary Flight Restriction is also filed with the FAA to prevent low flying aircraft from flying over the venting location during the blowdown,” Selkirk Fire said.

Keith Kinnaird can be reached by email at [email protected] and follow him on Twitter @KeithDailyBee.