A cooling system is planned for the Iroquois Gas Transmission System at 840 Oronoque Road, as part of a system-wide project to increase natural gas supply in New York.

The Planning and Zoning Board unanimously recently approved a coastal area management site plan for the project . The board added the condition that a licensed Connecticut surveyor survey the property.

The report assesses a project’s impact on coastal waterways, in this case, the Housatonic River. Project Director Robert Perless said the property is about 600 feet from the river, and said there would be no drainage to or impact on the river.

According to City Planner David B. Sulkis, the project, as a utility, is exempt from zoning, but not from a coastal area management review. A building project typically requires site plan approval.

In his report, Sulkis wrote, “The project does not appear to have any adverse impact on coastal resources.”

Iroquois previously came before the zoners on Feb. 19, 2008, for a review of its plans to construct two 10,300-horsepower compressor units at 840 Oronoque Road, which the board then approved as a formality because the project is regulated by the Federal Energy Regulatory Commission. That project was constructed in 2008 and operational in 2009.

According to the Iroquois website, the Milford cooling station is part of a larger project designed to increase capacity of the existing natural gas pipeline by 125 million cubic feet per day of natural gas to be delivered to New York utilities.

In the latest project, Iroquois plans to add horsepower to compression and gas cooling units at its compressor stations in Athens and Dover, N.Y., and Brookfield. The project adds 12,000 horsepower to each New York location, and 24,000 horsepower at the Brookfield site. Milford is receiving just gas cooling equipment.

Perless told the board the project was filed on Jan. 31 with FERC. The website states the anticipated FERC approval is early 2021 with construction to start in spring 2023 and to finish by Nov. 1, 2023.

According to the plans, the project will add a 60-foot by 45-foot cooling unit that is 15 feet high with associated equipment and accessory structures at the existing Milford compression station. The unit will be constructed on a new concrete pad, approximately 2,280 square feet in size, along with placement of fill, a gravel perimeter, a new driveway and related infrastructure.

The project will result in increased stormwater runoff, but this water will be retained within the existing detention pond.

In response to a board inquiry about the sound levels generated by the machinery, Michael Kinik, Iroquois director of engineering services, said, “FERC gives us strict guidance,” and said the average level day and night would be about 55 decibels.

“FERC wouldn’t grant us our certificate if we were exceeding that,” said Kinik.

Following construction, FERC requires a noise survey and if Iroquois is out of compliance, the company will be forced to fix the problem, said Kinik.

In response to another question, Perless said the majority of the natural gas used in the Northeast comes from fracked wells, commenting, “It’s hard to say exactly what percentage it is, but I would say it is the majority.”

Perless said this project adds 125,000 dekatherms, which on a peak day, is a little less than 10 percent of the company’s volume. A dekatherm is the energy content of 1,000 cubic feet of natural gas.

“On a non-peak day, they may utilize none of it. But primarily you’ll see this gas flow on the coldest of days in winter,” said Perless.

He said the project is being built for Con Edison and the National Grid. According to their websites, Con Edison serves New York City and Westchester, while National Grid serves Massachusetts, Rhode Island, and New York.

When asked about potential gas leaks, Kinik said the pipeline is welded, so there is really no possibility of leaks. He said the only real spots for leakage is where there are mechanical connections and at facilities. He said the pipeline is inspected annually for leaks and there are gas leak detectors within the buildings.

Kinik further said this project would not increase the potential for leaks because it is not adding pressure in Milford. He said in Milford as the capacity drops, the system would only raise pressure back up to the operating pressure. He said the maximum allowable operating pressure is 14,400 pounds.

“At Milford we are only adding the cooling. Upstream of Milford at three other sites, we are adding compression,” said Kinik.

The project includes a hydrocarbon abatement system, which are two small units next to the existing compressor building, said Kinik.

He said when the operating staff does maintenance, they have to relieve the gas out of the line. He said the standard practice today is to vent that gas into the atmosphere. With these units, the gas will be injected back into the pipe, resulting in less methane emissions at the site, said Kinik.