MONKTON — The Monkton selectboard was concerned when a local household’s drinking well was found to be contaminated with the known toxin pentachlorophenal soon after a utility pole sited close to the home’s drinking supply was replaced in March 2014.
The board took action that started a chain of events resulting in a state environmental report, recently posted on the Monkton town website, that raised flags about this widely used chemical, also known as “penta.”
The sheer prevalence of these penta-treated poles is “a real reason why you want to pay attention to how you deal with them,” said Monkton selectboard Chair Stephen Pilcher.
Nationwide, said Pilcher, there are an estimated 36 million penta-treated utility poles. Around 600,000 utility poles in Vermont are treated with penta.
Like creosote, chromated copper asenate, ammoniacal copper zinc arsenate, or copper naphthenate (CuNap), pentachlorophenal (or “penta”) is used as a heavy-duty wood preservative on utility poles. All are toxic. The Environmental Protection Agency identifies penta as “likely to be carcinogenic to humans.”
In Europe, signees to the “Stockholm-Basel-Rotterdam Convention on Persistent Organic Pollutants adopted resolutions to ban penta five years after 2015, though there’s a specific exemption in that ban for allowing penta in utility poles,” Pilcher said.
Apparently more than 50 nations worldwide have signed on to this convention, including the United States, but the U.S. Senate has not ratified the convention and therefore it does not have the force of law here. 
Monkton in 2014 asked for an investigation statewide of penta-related toxic incidents and a closer look into whether or how penta-treated poles could be used safely. In response, the Public Service Board formed a working group made up of representatives from utilities, state agencies (the Agency of Natural Resources, the Department of Health, the Agency of Agriculture and the Public Service Department), the Vermont Natural Resources Council, the treated wood industry, and the International Brotherhood of Electrical Workers (whose members climb, repair, install and handle the poles). Town of Monkton also got a seat with the group.
The working group released its report in April and Monkton posted the report to its website in May.
The report found that although rare, the penta contamination at the Monkton home was not an isolated incident. There have been seven incidents in Vermont of penta contamination caused by utility poles since 2007. Three incidents, including Monkton’s and incidents in Clarendon and Bennington, resulted in contamination of a home’s water supply. Four incidents, at sites in Middlesex, Waterbury, Bellows Falls and Dummerston, resulted in toxic releases into the soil.
All incidents were mitigated.
WHY USE PENTA
Heavy-duty preservatives like penta are important to the utility industry because a treated wood pole lasts five times longer than one that is not treated, giving a useful life of 60 or more years, according to the report. 
Although utility poles can also be made out of steel, fiberglass or concrete, treated wood is much cheaper.
In Vermont, most utility poles are made out of penta-treated southern pine. Interestingly, in mitigating the penta contamination of the water supplies in Clarendon and Bennington, the utilities replaced the penta-treated poles with cedar poles, which have naturally preserving properties. In earlier times, the naturally preserving properties of black locust made it the go-to wood for building timber crib dams and fence posts — no toxic chemicals needed. 
“The utilities really want to continue using penta, and they will continue using penta until they find something better or they’re pushed off of it,” Pilcher said. “So the utilities on this workgroup worked very hard to move to a ‘let’s develop some best practices to continue using it.’”
The report focuses on how to better manage installing, removing and storing penta-treated poles and how to better mitigate contaminated areas. It recommended that:
• Utilities should implement the report’s best manage practices.
• Utilities should evaluate costs and benefits of their pole materials and treatments.
• State agencies should monitor new EPA scientific data on penta.
• Utilities and state agencies should collaborate on further study.
Of particular concern, said Pilcher, is what happens to penta-treated utility poles once they’ve outlived their original purpose.
“Speaking for the town of Monkton, we’re a little uncertain about some of the reuse provisions,” he said. “It’s a big open question when they come out of the ground should we treat them as hazardous waste or not? The utility companies tend to sort of lay them on the ground and say, ‘If you want them, you can come pick them up’ because they’ve got to get rid of them.”
Pilcher continued, “So at least there’s some more formal stuff that’s part of this study that says, ‘Oh no, at minimum you need to give them the environmental factsheet and you probably ought to get a signed consent form indicating that the recipient understands the risks associated with the product.”
Reporter Gaen Murphree is at [email protected].
Click here to read the report.
Click here to download the DEC’s environmental fact sheet on safe reuses of treated wood.
For the DEC’s handout on what to do if you suspect penta contamination in your drinking water, see Appendix 5 of the report.
Editor’s note: This story was updated to clarify the fact that the convention banning penta was signed by many nations worldwide, not just in Europe.