Noise in a HUD environmental review

Subpart B of 24 CFR part 51 holds the noise standards that the Department of Housing and Urban Development (HUD) applies to its assistance. It sorts a site into one of three zones by its day-night average sound level (DNL), and the two higher zones bring special approvals, environmental review and sound attenuation. New construction, rehabilitation and existing buildings are treated differently.

Who the rule binds

Part 51's standards "shall apply to all HUD actions except where special provisions and exemptions are contained in each subpart" (24 CFR 51.4). The policy on new construction applies to "all HUD programs providing assistance, subsidy or insurance for housing, manufactured home parks, nursing homes, hospitals", and to programs that assist or insure land development, redevelopment or other facilities and services that open land to housing or noise sensitive development (24 CFR 51.101(a)(3)). It leaves out flood insurance, interstate land sales registration, research demonstration projects without new construction or reconstruction, and the emergency and disaster assistance it describes (24 CFR 51.101(a)(3)).

A responsible entity under 24 CFR part 58 "must take into consideration the noise criteria and standards in the environmental review process" and "shall address deviations from the standards in their environmental reviews" (24 CFR 51.101(a)(2)(i)). Parts 58 and 50 each list part 51's criteria and standards among their related authorities (24 CFR 58.5(i)(1), 50.4(k)). HUD program staff shall determine a proposed project's acoustical suitability at the earliest possible stage (24 CFR 51.102(b)).

What it asks

New construction. The policy is quoted below (24 CFR 51.101(a)(3)).
Existing buildings and rehabilitation. Noise alone does not bring denial of HUD support for buying or reselling an otherwise acceptable existing building, though HUD weighs it as a marketability factor (24 CFR 51.101(a)(4)). For major or substantial rehabilitation in the Normally Unacceptable and Unacceptable zones, HUD "actively shall seek to have project sponsors incorporate noise attenuation features" (24 CFR 51.101(a)(5)).
Goals. An exterior DNL of 55 decibels and an interior DNL of 45 are HUD goals (24 CFR 51.101(a)(8), (a)(9)).
The measure. DNL "is the 24-hour average sound level, in decibels, obtained after addition of 10 decibels to sound levels in the night from 10 p.m. to 7 a.m." (24 CFR 51.103(a)), counted from all sources. For loud impulsive sounds, 8 decibels are added, on an interim basis, to the DNL those sounds alone produce, unless the C-weighted DNL is used (24 CFR 51.103(b)). The standards usually apply 2 meters (6.5 feet) out from the building that houses the noise sensitive use, toward the predominant source (24 CFR 51.103(c)(1)).
The zones. The table of site acceptability standards in 51.103 sets three. Acceptable is a DNL not exceeding 65 decibels, with no special approvals or requirements. Normally Unacceptable is above 65 but not exceeding 75. Unacceptable is above 75. The last two carry special approvals, environmental review and attenuation (24 CFR 51.103(c)).
Attenuation. Approvals in the Normally Unacceptable zone require, for buildings with noise-sensitive uses, at least 5 decibels of added attenuation where the DNL is above 65 and not above 70, and at least 10 where it is above 70 and not above 75. In the Unacceptable zone the attenuation measures themselves need approval (24 CFR 51.104(a)(2)).
Review in the Normally Unacceptable zone. A project requires a Special Environmental Clearance, a term the subpart does not define, except that an Environmental Impact Statement (EIS) is required for a project in a largely undeveloped area, or where HUD's action would likely encourage incompatible land use in that zone (24 CFR 51.104(b)(1)(i)). The Program Assistant Secretary must then also concur (24 CFR 51.104(b)(1)(ii)). An area is largely undeveloped "unless the area within a 2-mile radius of the project boundary is more than 50 percent developed for urban uses and infrastructure (particularly water and sewers) is available and has capacity to serve the project" (24 CFR 51.104(b)(1)(ii)).
Review in the Unacceptable zone. "An EIS is required prior to the approval of projects with unacceptable noise exposure" (24 CFR 51.104(b)(2)). A project in or partly in the zone goes for approval to the Certifying Officer for an activity subject to part 58, or to HUD's Assistant Secretary for Community Planning and Development. Either may waive the EIS "in cases where noise is the only environmental issue and no outdoor noise sensitive activity will take place on the site"; a review under part 50 or part 58 is still made (24 CFR 51.104(b)(2)).
The exception. Where program objectives are found unachievable on sites meeting the 65 decibel standard, the Acceptable zone may, case by case, be shifted to 70 if all six listed conditions are satisfied, among them that noise is the only environmental issue (24 CFR 51.105(a)).
How the level is found. HUD field staff "shall make maximum use of noise data prepared by others when such data are determined to be current and adequately projected into the future" (24 CFR 51.106(a)). The section names airport, highway and military analyses, each usable on the conditions it prints (24 CFR 51.106(a)(1), (a)(2), (a)(3)). Compliance "shall, where necessary, be determined using noise assessment guidelines, handbooks, technical documents and procedures issued by the Department" (24 CFR 51.106(b)). Measurements may be performed where an assessment finds the site borderline, questionable or controversial (24 CFR 51.106(d)). Noise exposure shall be projected, as far as possible, to conditions expected at least 10 years after the project's or action's date (24 CFR 51.106(e)).

What it means for the Phase I and the consultant

ASTM E1527-21, the standard for the Phase I Environmental Site Assessment, is about releases of hazardous substances and petroleum products (E1527-21, 1.1, 1.1.1). Its list of matters outside its scope does not name noise and says it is not complete (E1527-21, 13.1.5), and nothing in its records review, site visit or interviews asks for a sound level.

A Phase I may hold the setting: its site visit covers public thoroughfares beside the subject property and the current uses of adjoining properties and the surrounding area (E1527-21, 9.4.3, 9.4.5, 9.4.8).

The rule turns on other facts: the DNL at the stated point, projected forward; the kind of work; how developed the area within 2 miles is; and whether noise is the only environmental issue. The zone, the need for measurements, and every approval and waiver rest with HUD or the responsible entity.

What the rule says

HUD assistance for the construction of new noise sensitive uses is prohibited generally for projects with unacceptable noise exposures and is discouraged for projects with normally unacceptable noise exposure.

24 CFR 51.101(a)(3), edition revised as of April 1, 2025

This page is general reference for environmental professionals. It does not review any project. The regulation is the authority, and the determinations of HUD or of the entity responsible for the review govern.