Planning board approves minor equipment changes for three Charlton battery storage lots; debate focuses on fire water capture and decommissioning sureties

The Town of Charlton Planning Board voted to accept field modifications to three battery energy storage projects — Lot F and Lot G on Larry’s Way and a site‑plan modification at 288 Sturbridge Road — after developers described an equipment substitution that reduces the container footprint but keeps overall capacity unchanged.

Tom Corbett of ZeroPoint Development (also identified as Superior Devco in the record) told the board the originally proposed Power Titan 1 model is no longer procurable; the manufacturer recommended the Power Titan 2 model and a medium‑voltage substation (MVS) skid that consolidates inverter/transformer functions. Corbett said the new packaging reduces the number of battery containers on each site (from eight to five in the examples presented) while keeping the same rated system capacity for the project’s application to the grid.

Corbett said the new battery containers are about 20 feet long by a bit over 8 feet wide (versus the older layout of about 26 feet by 5½ feet), and the MVS houses power conversion equipment on a single skid. He said wiring within the fenced areas will be underground, containers are not human‑habitable, and the neutral‑ground reactor and meter/recloser remain on pads. Corbett said cooling and battery chemistry remain consistent with prior filings: lithium‑iron‑phosphate cells (LFP) with liquid cooling inside the battery containers and fans at the DC conversion bays; mineral oil is used in pad‑mounted devices.

Board members and attendees pressed the applicant on fire‑safety measures and on how to manage potential contaminated runoff if water is used during emergency response. Multiple speakers referenced Energy Safety Response Group (ESRG) guidance and Electric Power Research Institute (EPRI) data showing responders collect and test water run‑off after battery fires. Corbett and others told the board that while deluge capability and piping were previously included in permits, ESRG and industry practice increasingly caution against pumping water into containers; instead the fire department uses water to cool neighboring equipment and limit spread. Planning members asked for confirmation that the fire department and conservation commission would sign off on any municipal water access or on a plan to capture fire water on site to prevent runoff into Katy Brook and nearby wetlands.

The board also pressed for documentation: model and manufacturer numbers for the Titan 2 units and for the new MVS, updated SDS (material safety data) sheets, property owner authorization letters for each parcel, and a decommissioning plan and surety that explicitly covers hazardous‑waste cleanup and wetland remediation. Corbett said manufacturers and bonding markets offer environmental/hazardous surety riders, typically costing roughly 1–3% of the decommissioning estimate; however he also said some surety forms contain clauses that exclude hazardous cleanup unless caused directly by the principal. Planning staff and a board member said that clause is a problem and requested legal review.

Practical site details addressed during the discussion: the applicant said typical minimum container separation (per prior permits) is 10 feet and that the new layout tightens the fence line but reduces the overall footprint. Corbett said noise analysis shows the new systems are about 15 decibels quieter at factory settings than earlier models and that modeled container noise at nearby receptors would be substantially lower than earlier equipment (he referenced example modeled levels near 80–81 decibels for the new system versus 91–96 decibels in older systems, depending on the model). He said expected lead time for the replacement equipment is availability by January and that project timelines are tied to a state incentive that requires systems be connected by Jan. 1, 2027.

After discussion, the board took three separate approvals by voice vote: accept the field modification for Lot F (contingent on final documentation and fire department sign‑off), accept the field modification for Lot G (same conditions), and approve the site‑plan modification for the 288 Southridge Road parcel. In each case the motions specified that final permits and building‑department approvals remain contingent on town staff and fire department review and on receipt of the requested technical documentation.

Board members emphasized they expect full documentation in the planning files before any energizing or occupancy: final manufacturer/model numbers and cut sheets; SDS/MDS sheets; confirmation of fire‑department sign‑off for on‑site water access or for an alternate captured‑runoff plan; a decommissioning estimate prepared or stamped by a professional engineer; and either an environmental surety or an explicit bonding instrument that covers hazardous‑waste cleanup and wetland remediation. Planning staff said the board will return to any item not settled in follow‑up and that decommissioning bond language will be reviewed by counsel.