The Sierra Madre Planning Commission on April 17, 2025 reviewed a draft rewrite of the city's noise ordinance and directed staff to refine enforcement language, harmonize hours across related code sections, and return with recommendations from its contractor and the police chief before scheduling a first reading.

The draft, prepared with help from Rincon Consultants, replaces the existing ambient-based limits with clearer numeric standards, adds low-frequency (DBC) criteria and a vibration threshold, and expands the ordinance's exemptions and measurement guidance. Commissioners praised the technical work but pressed staff and the consultant for clearer, enforceable procedures and device recommendations before the commission advances the ordinance to a public hearing.

Bill Vosti, program manager for Rincon, told the commission the rewrite aims to give code enforcement and planners "standards that are can be enforced" and to make the rules "easier to understand for code enforcement, planners and citizens." He described the key technical shifts: replacing relative "above ambient" limits with presumptive numeric limits keyed to the receiving land use; proposed daytime and nighttime numeric levels (for example, a commonly cited residential daytime number of about 60 dBA); a separate measurement metric, DBC, to capture low-frequency bass; and a vibration metric (a 72 vibration-decibel threshold drawn from Federal Transit Administration guidance) to address structure-shaking events.

Vosti and staff explained several implementation details. Construction thresholds in the draft use an industry metric of 80 dBA as an 8-hour exposure limit (a Federal Transit Administration reference). Because DBC data are less widely available than DBA data, the DBC provision in the draft is written as an increment above ambient (for example, 8 dB above ambient) rather than a single fixed number; that approach requires an on-site ambient reading before an event or activity begins. Vosti said ANSI-calibrated meters (Type 1 or Type 2) are the appropriate tools and noted the practical differences: "Type 1 meters are the most accurate, but Type 2 is what most people use in the field," and code text was drafted to require calibrated, standard meters and common settings (such as LEQ averaging and slow response) to increase consistency.

Commissioners focused heavily on enforceability. Commissioner Simcock said, "I'm very thankful that we added the DBC criteria," but asked how officers would measure ambient DBC if a loud party starts without prior notice. Director Lynn reported staff had already discussed enforcement with the police chief and the community services coordinator; Lynn said the chief asked the commission to discuss not only possible enforcement methods but also whether some draft provisions would be enforceable in practice: "Chief did brought up the question regarding enforcement and... he wanted the commission to discuss." City staff said they were not aware of recent administrative citations for noise and that typical practice is an initial warning followed by administrative citation procedures if the warning is not heeded.

Commissioners and staff asked the consultant to narrow and simplify the draft in several ways before the ordinance is advanced: reduce complexity by favoring simpler daytime/nighttime thresholds rather than a dense matrix of receiving-land-use categories; harmonize the ordinance's stated time windows with other code provisions (for example, construction-hours rules and an existing city landscape-equipment ordinance the council adopted previously); clarify whether the special-events exemption should be limited to city-approved events (such as Wistaria, the Fourth of July and city-permitted filming) or extended to privately organized events; and return with a recommended measurement interval (staff and Rincon had used a 15-minute LEQ averaging period in the draft but discussed reducing it) and precise meter models and procedures the city should require for enforcement.

On specific technical points the commission discussed: the DBC provision is intended to capture low-frequency bass that can rattle windows and building contents even when conventional DBA metrics show compliance; vibration language aims to address ground- or structure-borne motion (for which the draft proposes a 72 vibration-decibel threshold based on FTA/railroad literature); and the construction exemption language in the draft references a widely used 80 dBA/8-hour standard for heavy equipment. Commissioners repeatedly emphasized that measurement procedures (meter types, settings, averaging periods and sampling locations) must be practicable for city enforcement officers.

Staff and commissioners gave the following directions (no final ordinance adoption occurred at the meeting): ask Rincon to return with specific device and procedure recommendations and to work with the police chief on enforceability; harmonize hours in the noise draft with other municipal code sections and with the city council's recently adopted landscaping-equipment ordinance; treat special-event exemptions as applicable to city-approved events unless the commission directs otherwise; and delay any first-reading of an adoption ordinance until enforcement recommendations and police input are available. Planning staff said their recommendation at the meeting was that the commission review the draft, suggest amendments, and direct staff to schedule a public hearing, but commissioners asked staff to complete the enforcement and harmonization follow-ups first.

The commission did not take a formal vote on the ordinance text during the April 17 meeting. Staff said it will revise the draft to reflect the commission's direction and return with a new draft and proposed process plan for a public hearing and future action.

Next steps: staff will work with Rincon and the police department to refine measurement and enforcement language, harmonize hours and cross-references to other code sections, and bring a revised draft back to the Planning Commission for further consideration and a public hearing.