Proposed amendments to Chapters 4, 5, 6, 7, 8, 10, 31, 86, and 87 of Title 11 of the Mesa City Code pertaining to Battery Energy Storage Systems. The amendments include, but are not limited to: adding definitions for Battery Energy Storage System, Battery Energy Storage System Facility, Augmentation, and Nameplate Capacity; modifying land use tables to add Battery Energy Storage System and Battery Energy Storage System Facility; establishing development and other standards specific to Battery Energy Storage System Facilities. (Citywide) Ordinance No. 5976

Summary

Ordinance No. 5976, effective February 11, 2026, amends multiple chapters of the Mesa City Code to formally define and regulate Battery Energy Storage Systems (BESS) and BESS Facilities, which were previously prohibited. The legislation establishes criteria for classifying BESS as either a principal or accessory use: a principal use BESS Facility has a nameplate capacity of 5,000 kilowatts (5 megawatts) or greater and is permitted only in General Industrial (GI) or Heavy Industrial (HI) zoning districts with a City Council-approved Planned Area Development (PAD) Overlay. Accessory use BESS (under 5 MW, serving on-site functions) are permitted in various other districts without a PAD.

Key Development & Operational Standards:

• Separation Requirements: A minimum of 1,000 feet from residential zoning districts/uses, 400 feet from churches, parks, schools, or other sensitive uses, and 150 feet from commercial/industrial buildings (measured from the site screening wall).
• Fire Safety: Compliance with 2024 International Fire Code, NFPA 855, UL 9540, UL 9540A, including modular array limits (300 feet length/depth) and specific fire apparatus access roads (20-foot-wide every 300 feet, 26-foot-wide for larger arrays).
• Site Screening: Opaque walls/fences 1 foot above tallest equipment, made of high-quality materials, articulated every 40 feet.
• Operational Requirements: Mandatory initial and five years of annual sound studies to ensure noise levels do not exceed baseline at sensitive receptors, and a preliminary emergency response and decommissioning plan.

Two existing BESS Facilities (one near Signal Butte/Elliot Rd, operator Aypa; one near 202/24 Freeways, operator NextEra) are granted "Legal Procedurally Conforming Use/Structure" status, exempting them from rezoning but requiring full compliance with all other new standards. Violations carry civil penalties from $150 to $2,500 and can lead to criminal misdemeanors for habitual offenders.

Citizen Impact

This ordinance significantly impacts residents by establishing strict safety and compatibility standards for large-scale battery energy storage systems, which were previously unregulated. The 1,000-foot separation requirement from residential areas aims to protect homes from potential fire, noise, and visual impacts. Residents will benefit from enhanced emergency response planning and ongoing noise monitoring for these facilities, ensuring their health and safety are prioritized as Mesa expands its energy infrastructure.

Confidence

high