ROXBURY, NJ - The creation of malodorous hydrogen sulfide at Fenimore Landfill is a big problem, but Roxbury residents shouldn't worry too much about mercaptan or other smelly gases possibly being generated at the site, said a state official in a letter to a concerned resident. 

Ed Putnam, an assistant director in the state Department of Environmental Protection (DEP) Site Remediation Program, said the DEP views any release of mercaptan to be inconsequential compared with the huge amounts of hydrogen sulfide (H2S) that were wafting from the site and are now being collected and burned off.

Putnam was responding to a Feb. 19 letter from Roxbury resident Aaron Markworth, who said he was concerned that mercaptan might be coming from the site and causing health problems. Mercaptan, like H2S, has a noxious odor. It is added to odorless natural gas so people are aware of gas leaks. 

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"In the past couple of weeks there have been increased complaint reports of gas odors from Fenimore of different and varied types," wrote Markworth. "The hydrogen sulfide rotten egg odor of the past has been added to with rotten cabbage, skunk, garbage, natural gas and burning smells associated with mercaptans. I myself have noticed it numerous times driving down Mountain Road, especially late in the evening."

Markworth said he was worried about "chronic health effects from mercaptan exposure" and the lack of testing (of both the air and water at the site) for the substance. He also said he was concerned that "specific testing for mercaptans was never done because of perceived low concentrations" and the DEP's assumption the equipment now burning away the hydrogen sulfide being captured at Fenimore would also remove mercaptans."

In his response, Putnam pointed to a "fact sheet" published by the DEP in March 2014. The document said the state is not testing for mercaptan and sulfide compounds "because the concentrations of these compounds are present in landfill gas at significantly lower concentrations than H2S. Any trace amounts of other sulfur compounds emitted from the landfill would have been controlled to a similar high efficiency as H2S by the oxidizer.”

In his letter, Markworth accused the DEP and township of being “irresponsible” for assuming that the “only gas odor culprit is hydrogen sulfide” and he suggested that the mercaptan might be interfering with the functioning of air monitors around the landfill that are supposed to alert the state, township and residents about high H2S levels.

“The department doesn’t consider mercaptans to be of concern considering the levels of H2S that are present at the landfill,” wrote Putnam. He said problems with the monitors were determined to be caused by electrical interference during cold weather. Putnam said the “slightly elevated levels” of mercaptan being found by the monitors might not be from the landfill at all but coming, instead, from furnaces in the area

“If it were related to mercaptans from the material Strategic Environmental Partners (SEP) brought to the site, we would expect to see these readings during the summer too; and we do not,” wrote Putnam.

Markworth also told the DEP he was worried about marcpatan being released in runoff from the site and eventually entering the wells of residents. “Although Fenimore is being capped, the landfill still has no underliner and if the material stays wet from underground water seepage, hydrogen sulfide and mercaptans will continue to be produced and could escape,” he wrote.

Putnam responded that Markworth's fear about the runoff (leachate) appears to be related to the dump material that’s been at the site for decades. Municipal waste dumping at Fenimore ceased in the late 1970s and the site remained dormant until about three years ago when SEP, proposing to level it and install solar panels, began accepting construction debris as fill.

“The cap that DEP installed covers only the SEP material, since that material is the source of the H2S and our actions at the site were to abate the H2S odors,” wrote Putnam. “The cap includes an impermeable layer that not only prevents H2S gas from escaping but also prevents any rainwater from entering the material; which prevents any leachate from forming.”