Will methane gas from the capped landfill migrate to the new Highway Department facility if voters choose the Bowditch Road site? Some highway employees who will be working in the facility are concerned about it. Their boss, Mark Ketcham, superintendent of highways, said at last month's public forum that no one can make a 100-percent guarantee that no gases will enter the facility. The town's consultant, David Glass of Dvirka & Bartilucci Consulting Engineers, stated that the certainty that no gases will enter is as close to 100 percent as is possible.

Rob Gorcoff, highway worker, is skeptical. "They are their [the Town's] engineers, they'll say what they want them to say." Mr. Gorcoff's concerns regarding the methane at the capped landfill are based, in part, on an incident at the Town's Menantic Road recycling facility in which a town worker was hurt.

2002 well pit incident

A well pit, built before Mr. Ketcham's tenure, was used as a water source for the recycling facility, and largely consisted of two cesspool rings stacked on top of each other and a pump system. The well pit was located adjacent to the transformer building, the small building behind the compacting machines. The pump had lost its prime on July 8, 2002 and worker Bill Melanson climbed down.

"I went down into the pit to start the pump, climbed down about 20 feet. I couldn't breathe. I came up, caught my breath and went back down a second time. I still couldn't breathe," he said this week. Mark Ketcham remembered that Mr. Melanson was "overcome" by the gases on that second descent. Several emergency agencies responded. Gas testing equipment "red-lined" upon exposure to the gases in the pit. Mr. Melanson said that he was "checked out" by an ambulance crew then recovered without hospitalization. But he thinks he was lucky. "I could have died if I'd stayed down there any longer." Mr. Melanson thinks that building on the Bowditch Road site would be a "foolish mistake" based on his experience.

Methane is an odorless, colorless gas that is dangerous when it displaces oxygen or is exposed to a flame. Methane can be explosive when present in air at concentrations between five and 15 percent. Below five percent methane, called the lower explosive limit or LEL, the gas concentration is too lean to burn; more than 15 percent methane (the upper explosive limit) and the gas mixture does not have enough oxygen to combust. The methane at the bottom of the pit may have been too rich to combust. Gas meters may be calibrated to different combustible gases but those used for methane detection are usually set to sound an alarm if 10 to 20 percent of the LEL is present.

The Health Department ordered that the hazardous well pit be filled. Mr. Ketcham wanted to recover the pump equipment, but no one was allowed back in the pit, which was immediately filled, pump and all, with sand from Highway Department supplies on site.

According to Mr. Ketcham, the Menantic Road recycling center was built on top of older landfill that was covered by asphalt pavement over twenty years ago. The asphalt pavement serves as a cap for the old landfill, a cap that is not vented. Any remaining gases generated by the decomposing garbage beneath the parking lot dissipates into the air through uncovered soils adjacent to the parking lot.

The DEC required no further closure measures until the 2002 incident, which prompted the DEC to order the installation of test wells in the area. Mr. Ketcham has the paper work for a state grant "on my desk" to install three gas monitoring wells, two on the south and one on the north side of the recycling area. "The DEC does not think that venting is needed, just monitoring," Mr. Ketcham said. Mr. Ketcham also noted that methane was not a problem during construction of the cell phone tower behind the former well pit.

Long Island landfill incidents

Highway workers are also concerned about the risk of methane explosions in buildings near landfills, which have occurred at other Long Island facilities. When asked about this at the public forum, Mr. Glass replied that landfill incidents occurred about 20 years ago, but he wouldn't characterize these events as explosions.

Methane gas migrated from the Port Washington Landfill, an industrial waste disposal site, during the winters of 1979-1981 causing minor explosions in furnace areas of homes 100 to 500 feet from the landfill. Active and inactive gas venting systems were installed and monitored and the site was later placed on the National Priorities List of the Superfund program. During this same period (1979-1980), gases migrated from Islip's Blydenburgh Road Landfill and entered the basements of nearby homes. Two homes were abandoned and purchased by the town due to explosive levels of methane. In 1983, the Town of Islip installed a gas control system that it updates regularly to retain its assessment of posing "no apparent public health risks." At other large landfills on Long Island, like the one in Babylon, methane created problems in buildings constructed directly on top of closed landfill caps.

Methane is a fact of landfill life. Initially, decomposition in a landfill proceeds aerobically (using oxygen) producing such products as carbon dioxide and sulfur dioxide. When the oxygen is used up, anaerobic decomposition (without oxygen) yields methane, a gaseous hydrocarbon that is the principal component of natural gas. Methane is lighter than air and rises through permeable landfill materials but is stopped by impermeable caps. Venting of these caps allows the gas to escape, preventing a build-up of gas pressure. When these measures are not taken, excess gas pressure can force gases to move laterally through the soil as occurred in Port Washington and Islip.

Capped landfill gas levels

The landfill began as an active sand and gravel pit when the Menantic Road area was receiving garbage in the 1980s and earlier. When Shelter Island complied with the 1991 consent order from the DEC calling on the closure of Long Island landfills, the original quarry hole was only partially filled. As such, it is an irregularly shaped land area consisting of a ridge on the north and east sides descending into a sunken valley. During the capping of the landfill, a "hump" of sand, as Mr. Ketcham described it, was piled at the top of the landfill ridge, into which gases can rise. The 2.9-acre rubberized liner was placed on top of the entire landfill area in 1994, covering the ridge and sunken area. A venting system of four T-vents, eight-inch PVC pipe with slotted caps on the ends of the "T," was installed along the ridge and into slits cut in the rubber cap. The T-vents continuously release gases generated by decomposition of the garbage as required by state closure guidelines.

In addition to the vents, a gas monitoring well was installed for semi-annual tests of combustible gases. This well is located approximately 20 to 25 feet from the proposed Highway barn footprint. Combustible gases from this well are field sampled every June and December by personnel from Friend Laboratory Inc. of Waverly, New York. The combustible gases, measured in percent of the LEL of methane, have been decreasing over time, most recently from 13 percent of LEL in June 2003 to 5 percent of LEL in December 2003 and bottoming out at 0 percent in the August 2004 sampling.

Additional testing of soil gas was implemented by the Town of Shelter Island as part of the Bowditch Road Highway barn proposal. Seven locations were sampled a total of 10 times last April and May. Shallow soil probes, penetrating a maximum of about three feet, were inserted in five locations: (1) along the edge of the landfill cap, (2) at the southeast corner of the footprint of the proposed building, (3) near the footprint adjacent to Bowditch Road, (4) along the eastern boundary north of the cap, and (5) to the east on Peder Larsen's property. All shallow soil probe gas samples registered 0 percent of LEL for combustible gases.

Combustible gases were detected from the two sampled T-vents during six out of ten sampling events, indicating that the landfill is still cooking as expected. One sample measured a full 100 percent of LEL, but other detectable levels ranged from 40 to 88 percent. No combustible gas levels were detected during the four samplings on May 4 and May 12.

The DEC monitors all closed landfills for 30 years. If gas levels increase, the DEC will request that further measures be taken, such as updating or increasing venting systems. "The DEC is a tough organization," Mr. Ketcham said. He added that with their scrutiny "it's kind of hard to screw up these days," and create gas problems like those in Port Washington and Islip, which occurred prior to the DEC's landfill program.

Although the town's consultants believe that landfill gas will not migrate to the proposed building site, several measures will be built into the structure as a precaution. The building will be constructed on a slab foundation -- eliminating the possibility of gases entering a basement. An impermeable liner will be placed under the entire slab of the building. Finally, a gas monitoring system, with back-up power, will continuously sample the interior air to detect methane at concentrations well below the lower explosive limit.

Mr. Gorcoff believes that now, as in the past, the town is not looking out for the best interests of the highway workers. "They've never treated the Highway Department good. Now the small guys -- Gina [Sherman] and me -- we're gonna get the blame if the new barn doesn't pass." Mr. Gorcoff has asked Mark Ketcham to "Back your men."

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