Mesquite Data Center Projects: Ordinance 5259 CUP, Generator, Noise and Cooling Rules

Principal buildings must sit at least "three hundred (300) feet" from residential uses, schools, child care facilities, hospitals and assisted living. Generators, cooling equipment, battery energy storage, transformers, substations and fuel tanks must sit at least "five hundred (500) feet" from the same uses.

The larger equipment setback shapes the site layout and often the length of duct banks, fuel lines and internal roads, so civil and electrical scope can grow on a constrained parcel. The approved site plan becomes the baseline for change orders, and the builders risk values and the subcontract scopes typically follow it.

Section 3.514 says "All diesel generators shall meet or exceed EPA Tier 4 Final emission standards." Generators need a Level 3 enclosure limiting sound to 70 dBA at 25 feet. Testing is limited to Monday through Friday, 9 a.m. to 4 p.m., for no more than four hours, with one full-load test per generator per quarter, and emergency runs must be reported to the Director within 72 hours.

Those windows apply to commissioning as well as operations, so load bank and integrated systems testing can take longer than a schedule built around nights or weekends. Tier 4 Final units with aftertreatment and enclosures add equipment value, and fuel delivery and storage on site bring spill exposure during construction and startup.

The ordinance sets property-line limits of 65 dBA by day and 60 dBA at night, with 55 dBA at night next to residential. Low-frequency limits are 55 dB at 16, 31.5 and 63 Hz. "Within sixty (60) days of issuance of a Certificate of Occupancy," the operator must submit a post-construction sound study. If the study shows the site exceeds the limits, the operator "shall immediately undertake all measures necessary to achieve compliance."

That obligation lands after the certificate of occupancy, when the general contractor may have demobilized and the warranty clock has started. Who pays for barriers, silencers or equipment changes depends on the design responsibility, the acoustic specification and the warranty terms in the contracts. A noise retrofit is typically a contract and design question rather than an insurance claim, since liability policies generally respond to property damage or bodily injury rather than the cost of meeting a performance standard. Subcontractors who return for remediation work bring their own completed operations exposure.

Section 3.514 says "Only closed-loop or recycled water cooling systems are permitted." Potable water for open evaporative or once-through cooling is prohibited, and the applicant needs written confirmation of water capacity before final site plan approval.

Closed-loop systems put more of the cooling plant's value in chillers, pumps and piping that are tested and filled on site, and leak or freeze damage during commissioning is the kind of loss builders risk underwriters ask about. The water capacity letter is also a precondition to final site plan approval, so a delay there can hold up the start of work.

The City Council approves a decommissioning plan with the CUP. If a site is inactive for 36 months, decommissioning must start within 180 days and be substantially complete within 12 months. Section 3.514 does not require a bond, letter of credit or other financial security for that obligation.

With no security in the ordinance, there is no decommissioning bond for a surety to write under this section. A CUP condition, a development agreement or a lender may still ask for one, so read each approval. Whether a surety will write any bond is subject to underwriting, and a bond is a surety obligation, not insurance.

A Mesquite campus also sits under statewide rules: SB 6 (2025) large-load interconnection standards, including backup generation able to serve at least 50 percent of on-site demand that the utility may call on in emergencies, and the Comptroller's data center sales tax exemption, which excludes property incorporated into real estate. The Governor's 2026 letters directing an audit and a pause on TCEQ data center permits are executive directives whose duration may change.

The ordinance sets no insurance limit. Its effect on the program is through scope and timing: Tier 4 Final generators and fuel, closed-loop cooling plant and restricted test windows that can stretch commissioning, plus a post-occupancy noise obligation that tests the warranty and completed operations terms. Builders risk periods, testing terms and pollution coverage typically need to reflect those items. Terms can vary by carrier guidelines and programs, subject to underwriting and the terms of the bonds and policies issued.