Date: Fri 26-Sep-1997

Publication: Bee

Author: ANDYG

Quick Words:

Iroquois-pipeline

Full Text:

Portion Of Iroquois Pipeline To Be Replaced In Sandy Hook

BY ANDREW GOROSKO

An inspection of Iroquois Gas Transmission System's natural gas pipeline has

found a flaw in the pipeline where it runs beneath Route 34 in Sandy Hook.

Work crews have been doing preliminary excavation work where the pipeline

passes beneath Route 34 west of Great Quarter Road and east of Jordan Hill

Road.

To correct possible problems, the section of pipeline beneath Route 34 will be

removed Monday and replaced with a new section of pipe, according to Anita

Flanagan, an Iroquois spokeswoman.

The flawed pipe section doesn't pose any immediate public safety hazards, she

said.

On Monday at about 9:30 am, a main pipeline valve near the intersection of

Church Hill Road and Walnut Tree Hill Road will be closed to seal off a

section of the Iroquois pipeline. When the valve is closed, a section of

pipeline will be emptied of its gas, allowing the pipe replacement project

about six miles away under Route 34 to proceed.

When the pipeline section is vented of gas, residents living within 600 feet

of the valve may hear a loud noise similar to a jet engine. As the pipeline is

being emptied of natural gas, people will notice a smell of gas in the air

lasting for about 30 minutes, depending on weather conditions.

Natural gas, which is lighter than air, will rise into the air and dissipate

rapidly. An odorant which is added to gas to give it its characteristic smell,

however, lingers in the air, resulting in the odor after the gas is released

into the atmosphere.

Before the pipeline is vented of the gas, the pressure and volume of the gas

within the pipeline will have been reduced.

Because Iroquois is dedicated to pipeline safety, the company is taking a very

conservative approach in the repair project, according to Ms Flanagan. The

375-mile-long pipeline stretches from Long Island, beneath Long Island Sound,

through Connecticut and New York State to the Canadian border.

Iroquois detected the imperfection in the pipeline beneath Route 34 through

the use of a tool known as a "smart pig." The tool was sent through the

pipeline propelled by gas pressure. The tool electronically scans the inner

and outer surfaces of the pipeline and finds pipe sections which aren't

completely smooth, Ms Flanagan said.

A recent "pig run" through the 24-inch-diameter pipeline indicated there was

an imperfection in the pipe section beneath Route 34.

After such an imperfection is located, a visual inspection typically is made

to verify the data collected by the smart pig, according to Ms Flanagan. Such

an inspection typically is done by excavating the soil around the pipe. But

because the pipe section is located in a 30-inch-diameter concrete casing

beneath a state highway, a conventional inspection can't easily be performed,

according to Iroquois.

To expedite the project, Iroquois will completely remove and replace the pipe

section to reduce traffic disruptions and reduce service interruptions to its

customers, according to Ms Flanagan. The new section of gas pipeline will be

placed within the protective outer casing.

The exact nature of the problem is unclear, so Iroquois officials believe the

best approach is to remove the affected section and replace it with a new

section rather than attempt maintenance work on the flawed pipe in the field,

Ms Flanagan said. Doing such field maintenance would take several days rather

than the one day needed for pipe replacement, she added.

"This is very unusual.... This one is a puzzler to us," she said. "Once the

section of pipe has been removed, it will be sent for (metallurgical)

laboratory testing to determine the nature of the anomaly and possible reasons

for its presence."

The pipeline replacement work on Route 34 will involve use of heavy equipment.

Police will be posted at the site to control traffic when heavy equipment is

moved across the road, Ms Flanagan said.

The pipe replacement project which must be done in one work session is

expected to last 12 to 16 hours, meaning work will be completed Monday night

or early Tuesday morning.

The area excavated to install the new pipeline section will be physically

restored, according to Ms Flanagan.