Reworld says engineering changes and repeated tests put Bristol waste‑to‑energy plant within Connecticut noise limits

Reworld, the company that operates the Bristol waste‑to‑energy facility (renamed from Covanta in 2024), told a Connecticut public hearing that it has made a series of engineering modifications and commissioned multiple noise studies after residents complained of an intermittent low‑frequency “pulsing” sound.

The company representative known in the hearing transcript as Mr. Drew described how the plant converts municipal solid waste into steam and electricity and outlined steps taken since the first health‑district contact in October 2023. "So they sustainably manage waste. Waste that otherwise would have went to a landfill," Mr. Drew said, explaining the plant's process for combustion, steam generation and metal recovery. He said the plant handles about "220,000 tons per year" and receives roughly "200" truck deliveries a day.

Why it matters: Residents told the Bristol health district they were hearing a low‑frequency tone and a rhythmic pulsing. Those complaints triggered state and city noise‑limit reviews; the outcome affects whether the facility must undertake further engineering changes or operational restrictions to meet Connecticut's noise regulations.

Reworld told the hearing it first hired NCE to perform a diagnostic noise study in December 2023 and later paid for additional engineering work, including matching induced‑draft (ID) fan motors and designing acoustic inserts. Mr. Drew said the company replaced one ID‑fan motor in February 2024, installed initial inserts in June 2024, and later ordered modified inserts. The company also replaced a semi‑dry scrubber vessel during a March 2025 outage and installed new flue‑transition pieces on both units in spring 2025. "We installed them in, I believe, very early June, of 2024," he said of the initial inserts, and later described the scrubber installation as completed in March 2025.

Noise testing and technical dispute: Noise Control Engineering (NCE), which performed the company's December 2023 and follow‑up tests, concluded in its June 2025 compliance testing that measured off‑site levels met the applicable limits. Corey Nichon, introduced in the record as Corey Nichon (senior engineer, Noise Control Engineering), testified about equipment, standards and interpretation of Connecticut's regulations. "So a weighted is... how humans hear the world," Nichon said when explaining A‑weighting and why broadband metrics are used for regulatory comparisons. He described detecting a 125‑hertz tone and a beat (pulse) phenomenon the team attributed to two ID fans running at slightly different tonal frequencies.

Nichon described applying the state regulation's provision for a "prominent discrete tone," which (he testified) requires a 5‑decibel reduction to the standard broadband limit when a tone meets the statutory test at a receiving location. He summarized the regulatory baseline the team used: residential nighttime limits of 51 A‑weighted decibels and daytime of 61 A‑weighted decibels, and said that when the prominent‑tone reduction applies the effective nighttime ceiling becomes 46 dB.

The Bristol Health District engaged its own consultant (ATI) and issued a notice of violation in August 2024; NCE reviewed ATI's work and provided peer‑review comments to Reworld. Nichon testified that NCE found methodological gaps in the ATI report (for example, missing information on measurement durations, equipment calibration, and clear statement of which broadband metric was being compared) and that those gaps affected interpretation. He said NCE advised Reworld and then retested after the company's engineering changes.

Test chronology and results: NCE's sequence as described at the hearing is: diagnostic measurements (December 2023), compliance testing (June 2024) after initial retrofits, and a later compliance test (June 2025) after additional plant modifications. Nichon testified that the June 2025 compliance testing—conducted at the same off‑site receptor points used earlier—found no prominent discrete tones meeting the state's definition and that measured A‑weighted broadband levels at off‑site receptors were below the applicable limits. "We found that there were some problems in scribe tones... [but] even though they were prominent discrete tones and we applied the reduction, it still is underneath the level," Nichon said of earlier testing; for the latest test he said, "there were no prominent discrete tones calculated to be found." Reworld stated it spent an estimated couple hundred thousand dollars in the first year for consultants and retrofits and about $2,000,000 on the 2025 outages and replacements.

What was debated: Experts at the hearing agreed on basic measurement standards (ANSI/ASTM equipment and ASTM/ISO protocols were discussed) but differed on interpretation of how Connecticut's "prominent discrete tone" provision affects compliance comparisons. Nichon described applying the 5 dB reduction to the broadband limit for each receptor location where the tone test met the state's definition; the health district's report applied a different analytical approach, creating the technical dispute that the parties discussed and that NCE peer reviewed.

Remaining context and next steps: Reworld and NCE told the hearing that the company remains engaged with the health district and willing to allow agency consultants on site. The hearing officer kept the record open briefly for additional filings and asked litigants to file written closing arguments. No formal regulatory determination was entered during the session transcribed; the agency process (and any enforcement or mitigation obligations) will depend on the health district's review and any subsequent findings or remedies.

Ending note: At the hearing closing the officer directed written briefs on the technical and legal issues and provided an agency contact email (phho.dph@ct.gov) for follow‑up correspondence.