Ordinance Language Data Center Accountability for the Citizens of Dubuque County

ARTICLE VII — PERFORMANCE STANDARDS

Sec. 16-701. Noise and Vibration.

Consistent with the Dubuque County Regional Comprehensive Plan, Chapter 10, which directs sustained action to reduce or eliminate the long-term risks to people and property from hazards, the following noise and vibration standards apply:

• A.Baseline Study. Before the application is complete, and before any site disturbance, a pre-construction noise study prepared by a professional engineer with expertise in acoustics, including low-frequency analysis, shall establish Baseline Ambient Sound at representative monitoring locations along all Property Lines, selected by the County's independent expert to capture the points most susceptible to noise, across all operational times of day and night and across representative seasonal conditions, expressly including harvest-season agricultural operations, with compliance comparisons made against season-matched baseline data. Seasonal baseline data are used solely for season-matched comparison under subsection (B) and shall never increase the limits of subsection (C). Field measurements for the baseline study shall be performed by, or in the physical presence of, the County-selected acoustic expert, with full-spectrum octave-band and narrow-band analysis, expressly including all proposed cooling systems, electrical substations, on-site power generation, and Data Center Accessory Uses, and with special consideration for infrasound (below 20 Hz) beyond standard dB(C) measurement. The applicant shall fund, at submission, the County's retention of an independent acoustic expert with infrasound expertise to review the study and report to the County.
• B.Primary Operating Standard. Operations shall not cause sound levels at any Property Line to exceed Baseline Ambient Sound by more than three (3) dB, in dB(A) or dB(C), at any hour. Any exceedance is a violation unless expressly authorized as a condition of approval.
• C.Numeric Backstop. Sound attributable to the facility, measured at every Property Line, shall not exceed forty (40) dB(A) and fifty (50) dB(C) at any hour of any day, determined by comparison of facility-on and facility-off conditions using the baseline methodology. Where Baseline Ambient