The Vermont Public Service Board has released its final proposed rule for wind turbine noise.  After taking comments on the draft released a couple of months ago, the PSB chose to increase the proposed night time limit from 35dBA to 39dBA; the daytime limit remains 42dBA, three decibels lower than the current limit.

The rule now goes to the state legislature, where the Legislative Committee on Administrative Rules must sign off on them; the key question there will be whether the proposed rules are consistent with the state’s commitment to renewable energy, and whether the rules reflect the intent of the legislation that called for the PSB to develop new noise limits.  According to VTDigger, the sponsor of that bill, Chris Bray has said that “he trusts at this point that board members arrived at defensible sound limits, expressing confidence that the three-person PSB has the knowledge to come up with reasonable standards that also protect turbine neighbors from unreasonable harm.” Bray noted also that the dire predictions of wind supporters that stricter rules will preclude further development are similar to those raised when the state adopted new net-metering rules for solar power, which solar advocates decried as a death-knell for solar in Vermont; instead, solar development has boomed, mostly in areas such as brownfields, landfills, and old parking lots where the state was hoping new projects would be concentrated. “I think that’s good news,” Bray said. “Maybe two years from now we’ll look at the [wind turbine sound] rules and say, ‘This represents good news.’”

A couple of elements of the final plan should be kept in mind as this process moves forward.

First is the additional requirement that turbines be 10x their height from non-participating neighbors; this will amount to a 4000-5000 foot buffer, a distance is considered too extreme by wind proponents. There’s little doubt this distance would be necessary to meet a 35dB nighttime limit, though it’s possible that it could be slightly moderated with the higher 39dB limit (however, don’t forget that some earlier sound monitoring in VT found sound topping 39dB at times even at this distance). I would also note that in my visits in and around wind farms across the country, turbines do loom over the landscape in a surprising way, such that their presence can feel quite imposing at distances closer than a mile.

The second, and crucial, aspect of these new rules is that they do allow wind companies to make agreements with any landowner who lives closer or who would experience noise in excess of the limit. I suspect that this clause will give developers the flexibility they need to proceed with projects in areas with relatively few homes within a mile or so, which is really where they should be aiming to build anyway. Areas with many homes within easy earshot of wind farms are likely to become problematic for a critical mass of residents. Serious noise issues are relatively rare, affecting a small minority of those within earshot, though those who are affected often experience life-altering impacts; at the same time, many people are aware that they are not particularly sensitive to noise, and will be willing to live with modest or occasionally louder noise in exchange for modest compensation.  It’s a tricker proposition all around to navigate the “participating landowner” exceptions to these stricter siting standards, but it’s a reasonable choice to make if the PSB is aiming to minimize negative impacts on unwilling neighbors.

One into-the-weeds tweak in the final rules is that compliance testing will use 120 one-minute sound averages, rather than 12 ten-minute averages as proposed earlier; this may provide slightly better opportunities to capture transient peak sound levels, though as noted in March, there will always be moments of sound that are higher than the average, and often, higher than the regulatory threshold.  This is simply the nature of using averages in measuring compliance.

AEI’s coverage of the draft rules in March takes a deeper dive into the new rules and some of the contentious history in Vermont; it’s well worth a read if you missed it then.