Uxbridge planning board hears sound study for proposed 374 Hazel Street battery facility; public hearing continued to May 14

The Uxbridge Planning Board on May 7 heard a technical presentation and peer review of a sound study for a proposed energy storage facility at 374 Hazel Street and voted to continue the public hearing to May 14 at 6 p.m. while requiring the applicant to supply additional materials.

Mark Wallace, project manager for Tech Environmental, said the firm conducted eight days of baseline sound monitoring (March 7–14), screened out wind‑contaminated hours and selected an L90 quiet‑period average of 37 decibels as the baseline for compliance testing. Wallace told the board the project uses manufacturer and literature sound levels for eight storage units, two large inverters and two transformers and modeled the facility at maximum power to produce a conservative assessment.

Wallace said the state standard the project must meet is the MassDEP noise policy under 310 CMR 7.10, which treats a violation as an increase of more than 10 dB above the baseline (here, a 47 dB limit). "The town of Uxbridge does not have a noise ordinance, so we default to the MassDEP noise policy," Wallace said.

The unmitigated model reached the 47 dB threshold at the closest property lines. With an L‑shaped, tightly sealed sound barrier meeting roughly 2 lb/ft² density and other mitigation recommendations, the modeling showed predicted property‑line levels falling to about 41 dB, with a range of 27–41 dB across receptor points. Wallace noted those levels could still be audible during the quietest periods, but that the project would be in compliance with the MassDEP approach.

Christopher Menge of HMMH, who peer‑reviewed the study, told the board he found the assessment conservative and the mitigation appropriate for the nearest homes. "The expected noise levels from the facility really are well below the criteria that MassDEP has set," Menge said, but he added the peer review favored designs that sit several decibels below the regulatory +10 dB threshold rather than right at it.

Board members pressed the consultants on baseline selection. One board member noted single‑night low readings of 32–33 dB in the dataset and asked whether the board should use the single lowest reading or an averaged quiet‑hour metric. The consultants said their approach averaged the quietest hour across usable nights after removing contaminated data; they acknowledged MassDEP guidance does not prescribe a single calculation method and agreed to check prior local projects for methodological consistency.

The board requested several follow‑up items before concluding the hearing: electronic distance rings showing distances from the facility to the two nearest homes on Julia Drive (23 and 32 Julia Drive), a typical manufacturer cut sheet for the proposed sound barrier, the full revised plan package and the finalized civil drawings and safety documents. The applicant (Tom Corbett of ZP Battery DevCo) pledged to drop off a complete package and provide electronic files prior to the May 14 meeting.

The board formally moved and voted to continue the public hearing to May 14 at 6 p.m. The continuation will allow staff and board peer reviewers to confirm the baseline methodology used on prior projects, review the supplier cut sheets and verify modeled distances and mitigation details. If residents file complaints once the facility is operating, Menge explained, the Board of Health could ask MassDEP to conduct compliance measurements that compare background levels and facility‑on measurements (including an operator shutdown test).

The board also discussed fire‑safety follow‑ups that remain open: the fire department indicated a cistern requirement, but the applicant said capacity, reliability and winter operation need follow‑up with the fire chief and will be addressed in the next submittal.

Next steps: the applicant will supply the full revised submission electronically and in hard copy; the peer reviewer will confirm whether the methodology used here matches past local cases; and the board will reconvene the continued public hearing on May 14.