§ 51.1 24 CFR Subtitle A (4–1–04 Edition)

APPENDIX I TO SUBPART B TO PART 51—DEFI- 3535(d)); the National Environmental NITION OF ACOUSTICAL QUANTITIES Policy Act of 1969 (42 U.S.C. 4321); and the other statutes that are referred to Subpart C—Siting of HUD-Assisted Projects in this part. Near Hazardous Operations Handling Conventional Fuels or Chemicals of an [61 FR 13333, Mar. 26, 1996] Explosive or Flammable Nature § 51.3 Responsibilities. 51.200 Purpose. The Assistant Secretary for Commu- 51.201 Definitions. 51.202 Approval of HUD-assisted projects. nity Planning and Development is re- 51.203 Safety standards. sponsible for administering HUD’s en- 51.204 HUD-assisted hazardous facilities. vironmental criteria and standards as 51.205 Mitigating measures. set forth in this part. The Assistant 51.206 Implementation. Secretary for Community Planning and 51.207 Special circumstances. Development may be assisted by HUD 51.208 Reservation of administrative and officials in implementing the respon- legal rights. sibilities established by this part. HUD APPENDIX I TO SUBPART C TO PART 51—SPE- will identify these HUD officials and CIFIC HAZARDOUS SUBSTANCES their specific responsibilities through APPENDIX II TO SUBPART C TO PART 51—DE- VELOPMENT OF STANDARDS; CALCULATION FEDERAL REGISTER notice. METHODS [61 FR 13333, Mar. 26, 1996]

Subpart D—Siting of HUD Assisted Projects § 51.4 Program coverage. in Runway Clear Zones at Civil Airports Environmental standards shall apply and Clear Zones and Accident Poten- to all HUD actions except where spe- tial Zones at Military Airfields cial provisions and exemptions are con- 51.300 Purpose. tained in each subpart. 51.301 Definitions. 51.302 Coverage. 51.303 General policy. Subpart B— Abatement and 51.304 Responsibilities. Control 51.305 Implementation. § 51.100 Purpose and authority. AUTHORITY: 42 U.S.C. 3535(d), unless other- wise noted. (a) It is the purpose of this subpart B to: SOURCE: 44 FR 40861, July 12, 1979, unless (1) Call attention to the threat of otherwise noted. ; (2) Encourage the control of noise at Subpart A—General Provisions its source in cooperation with other Federal departments and agencies; § 51.1 Purpose. (3) Encourage land use patterns for The Department of Housing and housing and other noise sensitive Urban Development is providing pro- urban needs that will provide a suit- gram Assistant Secretaries and admin- able separation between them and istrators and field offices with environ- major noise sources; mental standards, criteria and guide- (4) Generally prohibit HUD support lines for determining project accept- for new construction of noise sensitive ability and necessary mitigating meas- uses on sites having unacceptable noise ures to insure that activities assisted exposure; by the Department achieve the goal of (5) Provide policy on the use of struc- a suitable living environment. tural and other noise attenuation measures where needed; and § 51.2 Authority. (6) Provide policy to guide implemen- This part implements the Depart- tation of various HUD programs. ment’s responsibilities under: The Na- (b) Authority. Specific authorities for tional Housing Act (12 U.S.C. 1701 et noise abatement and control are con- seq.); sec. 2 of the Housing Act of 1949 tained in the Act of 1972, (42 U.S.C. 1441); secs. 2 and 7(d) of the as amended (42 U.S.C. 4901 et seq.); and Department of Housing and Urban De- the General Services Administration, velopment Act (42 U.S.C. 3531 and Federal Management Circular 75–2;

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Compatible Land Uses at Federal Air- facilities and services which are di- fields. rected to making land available for housing or noise sensitive develop- [44 FR 40861, July 12, 1979, as amended at 61 FR 13333, Mar. 26, 1996] ment. The policy does not apply to re- search demonstration projects which § 51.101 General policy. do not result in new construction or re- (a) It is HUD’s general policy to pro- construction, flood insurance, inter- vide minimum national standards ap- state land sales egistration, or any ac- plicable to HUD programs to protect tion or emergency assistance under dis- citizens against excessive noise in their aster assistance provisions or appro- communities and places of residence. priations which are provided to save (1) Planning assistance. HUD requires lives, protect property, protect public that grantees give adequate consider- health and safety, remove debris and ation to noise exposures and sources of wreckage, or assistance that has the ef- noise as an integral part of the urban fect of restoring facilities substantially environment when HUD assistance is as they existed prior to the disaster. provided for planning purposes, as fol- (4) HUD support for existing construc- lows: tion. Noise exposure by itself will not (i) Particular emphasis shall be result in the denial of HUD support for placed on the importance of compatible the resale and purchase of otherwise land use planning in relation to air- acceptable existing buildings. However, ports, highways and other sources of environmental noise is a marketability high noise. factor which HUD will consider in de- (ii) Applicants shall take into consid- termining the amount of insurance or eration HUD environmental standards other assistance that may be given. impacting the use of land. (5) HUD support of modernization and (2) Activities subject to 24 CFR part 58. rehabilitation. For modernization (i) Responsible entities under 24 CFR projects located in all noise exposed part 58 must take into consideration areas, HUD shall encourage noise at- the noise criteria and standards in the tenuation features in alterations. For environmental review process and con- major or substantial rehabilitation sider ameliorative actions when noise projects in the Normally Unacceptable sensitive land development is proposed and Unacceptable noise zones, HUD ac- in noise exposed areas. Responsible en- tively shall seek to have project spon- tities shall address deviations from the sors incorporate noise attenuation fea- standards in their environmental re- tures, given the extent and nature of views as required in 24 CFR part 58. the rehabilitation being undertaken (ii) Where activities are planned in a and the level or exterior noise expo- noisy area, and HUD assistance is con- sure. In Unacceptable noise zones, HUD templated later for housing and/or shall strongly encourage conversion of other noise sensitive activities, the re- noise-exposed sites to land uses com- sponsible entity risks denial of the patible with the high noise levels. HUD assistance unless the HUD stand- (6) Research, guidance and publica- ards are met. tions. HUD shall maintain a continuing (3) HUD support for new construction. program designed to provide new HUD assistance for the construction of knowledge of noise abatement and con- new noise sensitive uses is prohibited trol to public and private bodies, to de- generally for projects with unaccept- velop improved methods for antici- able noise exposures and is discouraged pating noise encroachment, to develop for projects with normally unaccept- noise abatement measures through able noise exposure. (Standards of ac- land use and building construction ceptability are contained in § 51.103(c).) practices, and to foster better under- This policy applies to all HUD pro- standing of the consequences of noise. grams providing assistance, subsidy or It shall be HUD’s policy to issue guid- insurance for housing, manufactured ance documents periodically to assist home parks, nursing homes, hospitals, HUD personnel in assigning an accept- and all programs providing assistance ability category to projects in accord- or insurance for land development, re- ance with noise exposure standards, in development or any other provision of evaluating noise attenuation measures,

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and in advising local agencies about time in the decision process. Every at- noise abatement strategies. The guid- tempt shall be made to insure that ap- ance documents shall be updated peri- plicants’ site choices are consistent odically in accordance with advances with the policy and standards con- in the state-of-the-art. tained herein. (7) Construction equipment, building (b) Notice to applicants. At the earliest equipment and appliances. HUD shall en- possible stage, HUD program staff courage the use of quieter construction shall: equipment and methods in population (1) Determine the suitability of the centers, the use of quieter equipment acoustical environment of proposed and appliances in buildings, and the projects; use of appropriate noise abatement (2) Notify applicants of any adverse techniques in the design of residential or questionable situations; and structures with potential noise prob- (3) Assure that prospective applicants lems. are apprised of the standards contained (8) Exterior noise goals. It is a HUD herein so that future site choices will goal that exterior noise levels do not be consistent with these standards. exceed a day-night average level (c) Interdepartmental coordination. of 55 decibels. This level is rec- HUD shall foster appropriate coordina- ommended by the Environmental Pro- tion between field offices and other de- tection Agency as a goal for outdoors partments and agencies, particularly in residential areas. The levels rec- the Environmental Protection Agency, ommended by EPA are not standards the Department of Transportation, De- and do not take into account cost or partment of Defense representatives, feasibility. For the purposes of this and the Department of Veterans Af- regulation and to meet other program fairs. HUD staff shall utilize the ac- objectives, sites with a day-night aver- ceptability standards in commenting age sound level of 65 and below are ac- on the prospective impacts of transpor- ceptable and are allowable (see Stand- tation facilities and other noise gen- ards in § 51.103(c)). erators in the Environmental Impact (9) Interior noise goals. It is a HUD Statement review process. goal that the interior auditory envi- [44 FR 40861, July 12, 1979, as amended at 54 ronment shall not exceed a day-night FR 39525, Sept. 27, 1989; 61 FR 13333, Mar. 26, average sound level of 45 decibels. At- 1996] tenuation measures to meet these inte- rior goals shall be employed where fea- § 51.103 Criteria and standards. sible. Emphasis shall be given to noise These standards apply to all pro- sensitive interior spaces such as bed- grams as indicated in § 51.101. rooms. Minimum attenuation require- (a) Measure of external noise environ- ments are prescribed in § 51.104(a). ments. The magnitude of the external (10) Acoustical privacy in multifamily noise environment at a site is deter- buildings. HUD shall require the use of mined by the value of the day-night av- building design and acoustical treat- erage sound level produced as the re- ment to afford acoustical privacy in sult of the accumulation of noise from multifamily buildings pursuant to re- all sources contributing to the external quirements of the Minimum Property noise environment at the site. Day- Standards. night average sound level, abbreviated [44 FR 40861, July 12, 1979, as amended at 50 as DNL and symbolized as Ldn, is the 24- FR 9268, Mar. 7, 1985; 61 FR 13333, Mar. 26, hour average sound level, in decibels, 1996] obtained after addition of 10 decibels to sound levels in the night from 10 p.m. § 51.102 Responsibilities. to 7 a.m. Mathematical expressions for (a) Surveillance of noise problem areas. average sound level and day-night av- Appropriate field staff shall maintain erage sound level are stated in the Ap- surveillance of potential noise problem pendix I to this subpart. areas and advise local officials, devel- (b) Loud impulsive . On an in- opers, and planning groups of the terim basis, when loud impulsive unacceptability of sites because of sounds, such as explosions or sonic noise exposure at the earliest possible booms, are experienced at a site, the

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day-night average sound level produced apply at a location 2 meters (6.5 feet) by the loud impulsive sounds alone from the building housing noise sen- shall have 8 decibels added to it in as- sitive activities in the direction of the sessing the acceptability of the site predominant noise source. Where the (see Appendix I to this subpart). Alter- building location is undetermined, the natively, the C-weighted day-night av- standards shall apply 2 meters (6.5 feet) erage sound level (LCdn) may be used from the building setback line nearest without the 8 decibel addition, as indi- to the predominant noise source. The cated in § 51.106(a)(3). Methods for as- standards shall also apply at other lo- sessing the contribution of loud impul- cations where it is determined that sive sounds to day-night average sound quiet outdoor space is required in an level at a site and mathematical ex- area ancillary to the principal use on pressions for determining whether a the site. sound is classed as ‘‘loud impulsive’’ (2) The noise environment inside a are provided in the Appendix I to this building is considered acceptable if: (i) subpart. The noise environment external to the (c) Exterior standards. (1) The degree building complies with these standards, of acceptability of the noise environ- and (ii) the building is constructed in a ment at a site is determined by the manner common to the area or, if of sound levels external to buildings or uncommon construction, has at least other facilities containing noise sen- the equivalent noise attenuation char- sitive uses. The standards shall usually acteristics.

SITE ACCEPTABILITY STANDARDS

Special approvals and require- Day-night average sound level (in decibels) ments

Acceptable ...... Not exceeding 65 dB(1) ...... None. Normally Unacceptable ...... Above 65 dB but not exceeding 75 dB ...... Special Approvals (2) Environmental Review (3). Attenuation (4). Unacceptable ...... Above 75 dB ...... Special Approvals (2). Environmental Review (3). Attenuation (5). Notes: (1) Acceptable threshold may be shifted to 70 dB in special circumstances pursuant to § 51.105(a). (2) See § 51.104(b) for requirements. (3) See § 51.104(b) for requirements. (4) 5 dB additional attenuation required for sites above 65 dB but not exceeding 70 dB and 10 dB additional attenuation re- quired for sites above 70 dB but not exceeding 75 dB. (See § 51.104(a).) (5) Attenuation measures to be submitted to the Assistant Secretary for CPD for approval on a case-by-case basis.

[44 FR 40861, July 12, 1979, as amended at 49 FR 12214, Mar. 29, 1984]

§ 51.104 Special requirements. in Normally Unacceptable Noise Zones require a minimum of 5 decibels addi- (a)(1) Noise attenuation. Noise attenu- tional sound attenuation for buildings ation measures are those required in addition to attenuation provided by having noise-sensitive uses if the day- buildings as commonly constructed in night average sound level is greater the area, and requiring open windows than 65 decibels but does not exceed 70 for ventilation. Measures that reduce decibels, or a minimum of 10 decibels of external noise at a site shall be used additional sound attenuation if the wherever practicable in preference to day-night average sound level is great- the incorporation of additional noise er than 70 decibels but does not exceed attenuation in buildings. Building de- 75 decibels. Noise attenuation measures signs and construction techniques that in Unacceptable Noise Zones require provide more noise attenuation than the approval of the Assistant Secretary typical construction may be employed for Community Planning and Develop- also to meet the noise attenuation re- ment, or the Certifying Officer for ac- quirements. tivities subject to 24 CFR part 58. (See (2) Normally unacceptable noise zones § 51.104(b)(2).) and unacceptable noise zones. Approvals

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(b) Environmental review requirements. § 51.105 Exceptions. Environmental reviews shall be con- (a) Flexibility for non-acoustic benefits. ducted pursuant to the requirements of Where it is determined that program 24 CFR parts 50 and 58, as applicable, or objectives cannot be achieved on sites other environmental regulations issued meeting the acceptability standard of by the Department. These require- 65 decibels, the Acceptable Zone may ments are hereby modified for all projects proposed in the Normally Un- be shifted to Ldn 70 on a case-by-case acceptable and Unacceptable noise ex- basis if all the following conditions are posure zones as follows: satisfied: (1) Normally unacceptable noise zone. (1) The project does not require an (i) All projects located in the Normally Environmental Impact Statement Unacceptable Noise Zone require a Spe- under provisions of § 51.104(b)(1) and cial Environmental Clearance except noise is the only environmental issue. an EIS is required for a proposed (2) The project has received a Special project located in a largely undevel- Environmental Clearance and has re- oped area, or where the HUD action is ceived the concurrence of the Environ- likely to encourage the establishment mental Clearance Officer. of incompatible land use in this noise (3) The project meets other program zone. goals to provide housing in proximity (ii) When an EIS is required, the con- to employment, public facilities and currence of the Program Assistant Sec- transportation. retary is also required before a project (4) The project is in conformance can be approved. For the purposes of with local goals and maintains the this paragraph, an area will be consid- character of the neighborhood. ered as largely undeveloped unless the (5) The project sponsor has set forth area within a 2-mile radius of the reasons, acceptable to HUD, as to why project boundary is more than 50 per- the noise attenuation measures that cent developed for urban uses and in- would normally be required for new frastructure (particularly water and construction in the Ldn 65 to Ldn 70 zone sewers) is available and has capacity to cannot be met. serve the project. (6) Other sites which are not exposed (iii) All other projects in the Nor- to noise above Ldn 65 and which meet mally Unacceptable zone require a Spe- program objectives are generally not cial Environmental Clearance, except available. where an EIS is required for other rea- The above factors shall be documented sons pursuant to HUD environmental and made part of the project file. policies. (2) Unacceptable noise zone. An EIS is [44 FR 40861, July 12, 1979, as amended at 61 required prior to the approval of FR 13334, Mar. 26, 1996] projects with unacceptable noise expo- sure. Projects in or partially in an Un- § 51.106 Implementation. acceptable Noise Zone shall be sub- (a) Use of available data. HUD field mitted to the Assistant Secretary for staff shall make maximum use of noise Community Planning and Develop- data prepared by others when such ment, or the Certifying Officer for ac- data are determined to be current and tivities subject to 24 CFR part 58, for adequately projected into the future approval. The Assistant Secretary or and are in terms of the following: the Certifying Officer may waive the (1) Sites in the vicinity of airports. The EIS requirement in cases where noise noise environment around airports is is the only environmental issue and no described sometimes in terms of Noise outdoor noise sensitive activity will Exposure Forecasts, abbreviated as take place on the site. In such cases, an NEF or, in the State of California, as environmental review shall be made Community Noise Equivalent Level, pursuant to the requirements of 24 CFR abbreviated as CNEL. The noise envi- parts 50 or 58, as appropriate. ronment for sites in the vicinity of air- [44 FR 40861, July 12, 1979, as amended at 61 ports for which day-night average FR 13333, Mar. 26, 1996] sound level data are not available may

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be evaluated from NEF or CNEL anal- erage sound level used on an interim yses using the following conversions to basis to determine site suitability for DNL: non-impulsive sounds apply to the LCdn. (4) Use of areawide acoustical data. DNL≈ NEF+35 DNL ≈ CNEL HUD encourages the preparation and use of areawide acoustical information, (2) Sites in the vicinity of highways. such as noise contours for airports. Highway projects receiving Federal aid Where such new or revised contours be- are subject to noise analyses under the come available for airports (civil or procedures of the Federal Highway Ad- military) and military installations ministration. Where such analyses are they shall first be referred to the HUD available they may be used to assess State Office (Environmental Officer) sites subject to the requirements of for review, evaluation and decision on this standard. The Federal Highway appropriateness for use by HUD. The Administration employs two alternate HUD State Office shall submit revised sound level descriptors: (i) The A- contours to the Assistant Secretary for weighted sound level not exceeded Community Planning and Development more than 10 percent of the time for for review, evaluation and decision the highway design hour traffic flow, whenever the area affected is changed symbolized as L10; or (ii) the equivalent by 20 percent or more, or whenever it is sound level for the design hour, sym- determined that the new contours will bolized as Leq. The day-night average have a significant effect on HUD pro- sound level may be estimated from the grams, or whenever the contours are design hour L or L values by the fol- 10 eq not provided in a methodology accept- lowing relationships, provided heavy able under § 51.106(a)(1) or in other trucks do not exceed 10 percent of the cases where the HUD State Office de- total traffic flow in vehicles per 24 termines that Headquarters review is hours and the traffic flow between 10 warranted. For other areawide acous- p.m. and 7 a.m. does not exceed 15 per- tical data, review is required only cent of the average daily traffic flow in where existing areawide data are being vehicles per 24 hours: utilized and where such data have been DNL≈ L10 (design hour)—3 decibels changed to reflect changes in the meas- DNL ≈ Leg (design hour) decibels urement methodology or underlying noise source assumptions. Requests for Where the auto/truck mix and time of determination on usage of new or re- day relationships as stated in this sec- vised areawide data shall include the tion do not exist, the HUD Noise As- following: sessment Guidelines or other noise analysis shall be used. (i) Maps showing old, if applicable, (3) Sites in the vicinity of installations and new noise contours, along with producing loud impulsive sounds. Certain brief description of data source and Department of Defense installations methodology. produce loud impulsive sounds from ar- (ii) Impact on existing and prospec- tillery firing and bombing practice tive urbanized areas and on develop- ranges. Noise analyses for these facili- ment activity. ties sometimes encompass sites that (iii) Impact on HUD-assisted projects may be subject to the requirements of currently in processing. this standard. Where such analyses are (iv) Impact on future HUD program available they may be used on an in- activity. Where a field office has deter- terim basis to establish the accept- mined that immediate approval of new ability of sites under this standard. areawide data is necessary and war- The Department of Defense uses day- ranted in limited geographic areas, the night average sound level based on C- request for approval should state the weighted sound level, symbolized LCdn, circumstances warranting such ap- for the analysis of loud impulsive proval. Actions on proposed projects sounds. Where such analyses are pro- shall not be undertaken while new vided, the 8 decibel addition specified areawide noise data are being consid- in § 51.103(b), is not required, and the ered for HUD use except where the pro- same numerical values of day-night av- posed location is affected in the same

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manner under both the old and new (f) Reduction of site noise by use of noise data. berms and/or barriers. If it is determined (b) Site assessments. Compliance with by adequate analysis that a berm and/ the standards contained in § 51.103(c) or barrier will reduce noise at a hous- shall, where necessary, be determined ing site, and if the barrier is existing or using noise assessment guidelines, there are assurances that it will be in handbooks, technical documents and place prior to occupancy, the environ- procedures issued by the Department. mental noise analysis for the site may (c) Variations in site noise levels. In reflect the benefits afforded by the many instances the noise environment berm and/or barrier. In the environ- will vary across a site, with portions of mental review process under § 51.104(b), the site being in an Acceptable noise the location height and design of the berm and/or barrier shall be evaluated environment and other portions in a to determine its effectiveness, and im- Normally Unacceptable noise environ- pact on design and aesthetic quality, ment. The standards in § 51.103(c) shall circulation and other environmental apply to the portions of a building or factors. buildings used for residential purposes and for ancillary noise sensitive open [44 FR 40861, July 12, 1979, as amended at 61 spaces. FR 13334, Mar. 26, 1996] (d) Noise measurements. Where noise APPENDIX I TO SUBPART B OF PART 51— assessments result in a finding that the DEFINITION OF ACOUSTICAL QUANTITIES site is borderline or questionable, or is controversial, noise measurements 1. Sound Level. The quantity in decibels may be performed. Where it is deter- measured with an instrument satisfying re- mined that noise measurements are re- quirements of American National Standard quired, such measurements will be con- Specification for Type 1 Sound Level Meters S1.4–1971. Fast time-averaging and A-fre- ducted in accordance with methods and quency weighting are to be used, unless oth- measurement criteria established by ers are specified. The with the Department. Locations for noise the A-weighting is progressively less sen- measurements will depend on the loca- sitive to sounds of frequency below 1,000 tion of noise sensitive uses that are hertz (cycles per second), somewhat as is the nearest to the predominant noise ear. With fast time averaging the sound level meter responds particularly to recent sounds source (see § 51.103(c)). almost as quickly as does the ear in judging (e) Projections of noise exposure. In ad- the loudness of a sound. dition to assessing existing exposure, 2. Average Sound Level. Average sound future conditions should be projected. level, in decibels, is the level of the mean- To the extent possible, noise exposure square A-weighted sound pressure during the shall be projected to be representative stated time period, with reference to the square of the standard reference sound pres- of conditions that are expected to exist sure of 20 micropascals. at a time at least 10 years beyond the Day-night average sound level, abbreviated date of the project or action under re- as DNL, and symbolized mathematically as view. Ldn is defined as:

Time t is in seconds, so the limits shown in A-weighted sound level, the quantity in deci- hours and minutes are actually interpreted bels measured by an instrument satisfying

in seconds. LA(t) is the time varying value of requirements of American National Standard

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Specification for Type 1 Sound Level Meters (a) Establish safety standards which S1.4–1971. can be used as a basis for calculating 3. Loud Impulsive Sounds. When loud impul- acceptable separation distances (ASD) sive sounds such as sonic booms or explo- sions are anticipated contributors to the for HUD-assisted projects from spe- noise environment at a site, the contribution cific, stationary, hazardous operations to day-night average sound level produced by which store, handle, or process haz- the loud impulsive sounds shall have 8 deci- ardous substances; bels added to it in assessing the accept- (b) Alert those responsible for the ability of a site. siting of HUD-assisted projects to the A loud impulsive sound is defined for the purpose of this regulation as one for which: inherent potential dangers when such (i) The sound is definable as a discrete projects are located in the vicinity of event wherein the sound level increases to a such hazardous operations; maximum and then decreases in a total time (c) Provide guidance for identifying interval of approximately one second or less those hazardous operations which are to the ambient background level that exists without the sound; and most prevalent; (ii) The maximum sound level (obtained (d) Provide the technical guidance re- with slow averaging time and A-weighting of quired to evaluate the degree of danger a Type 1 sound level meter whose character- anticipated from explosion and ther- istics comply with ANSI S1.4–1971) exceeds mal radiation (fire); and the sound level prior to the onset of the event by at least 6 decibels; and (e) Provide technical guidance re- (iii) The maximum sound level obtained quired to determine acceptable separa- with fast averaging time of a sound level tion distances from such hazards. meter exceeds the maximum value obtained with slow averaging time by at least 4 deci- [49 FR 5103, Feb. 10, 1984, as amended at 61 bels. FR 13334, Mar. 26, 1996] [44 FR 40861, July 12, 1979; 49 FR 10253, Mar. § 51.201 Definitions. 20, 1984; 49 FR 12214, Mar. 29, 1984] The terms Department and Secretary Subpart C—Siting of HUD-Assisted are defined in 24 CFR part 5. Projects Near Hazardous Op- Acceptable separation distance (ASD)— erations Handling Conven- means the distance beyond which the tional Fuels or Chemicals of explosion or combustion of a hazard is not likely to cause structures or indi- an Explosive or Flammable viduals to be subjected to blast over- Nature pressure or thermal radiation flux lev- els in excess of the safety standards in AUTHORITY: 42 U.S.C. 3535(d). § 51.203. The ASD is determined by ap- SOURCE: 49 FR 5103, Feb. 10, 1984, unless plying the safety standards established otherwise noted. by this subpart C to the guidance set forth in HUD Guidebook, ‘‘Siting of § 51.200 Purpose. HUD-Assisted Projects Near Hazardous The purpose of this subpart C is to: Facilities.’’

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