[From the U.S. Government Printing Office, www.gpo.gov]
GEOTHERMAL NOISE LEVEL GUIDELINES 1981 IIJ GB Al 1199.7 H3 -G46 1981 GEOTHERMAL NO may 7. 19si ....,Geothermal Noise Level Guidelines "County of Hawaii -Planning Department DEPARTME1,41( OF AND* COASTAL Zoj@,,TE fiCONOMIC- DEVEW'IMENT P. 0. Box 235, INFORMATION CE.,N-r.Ep Honolulu, Hawaii 96A04 .-INTRODUCTIO,4 qM1 in granting Special Permits for the-exploration and development nof geothermal resources in the-Puna District, the Planning -Department and CouLhission found that there were potent.ial adverse impacts to the surrounding area which may result from the geothermal. ---,operations. Consequently,.stringent controls and conditions were -.,attached to the respectivepermits. The.Planning Commission -,assigned tne Planning Director the primary responsibility for the 7monitoring and enforcing of these conditions. -in light of these responsibilities and the .numerous noise. @related complaints received from residents-of the Puna District -concerning certain geothermal drilling operations,, the Planning -Department has developed the following.guidelines to determine -acceptanle noise levels for both -geothermal exploration and @production. -!rhese noise levels are intended to provide the Planning Director 'with the necessary guidance to review and assess geothermal operations on a case. specifi*c ijasis to determine whetner a: noise nuisance exists or not. Based on this review, should the Planning Director find that the acceptaola noise levels are being exceeded and that the residents are being significantly adversely impacted by that noise, he can: (1) invoke more stringent noise mitigative procedures and/or mitigative devices; or (2) cease futher geothermal activity in accordance with the appropriate provistions of the Special Permits. BACKGROUND In reviewing the available literature, there are numerous guidelines which may possibly be applied to the noise problem resulting from geothermal operations. These guidelines are summarized in Table 1 below: TABLE 1 ACCEPTABLE NOISE LEVEL STANDARDS NOISE LIMIT MEASUREMENT POINT GENERAL STANDARDS U.S. ENVIRONMENTAL Outdoor: 55 dBA Ldn Nearest inhabited PROTECTION AGENCY Indoor: 45 dBA Ldn residence U.S. DEPARTMENT OF Outdoor: 65 dBA Day Residence HOUSING AND URBAN 55 dBA Night DEVELOPMENT State Department Res: 55 dBA Day Property Line of Health Community 45 dBA Night Noise regulations Bus/Apt 60 dBA Day for Oahu 50 dBA Night Ag/Ind 70 dBa -2- r GEOTHERMAL, STANDARDS U.S. GEOLOGICAL Uutdoor: 65 dBA Lease Boundary or 0.5 SERVICE (Federal Milq whichever is Geothermal leases) greater SONOMA COUNTY, Outdoor: 65' dBA Day Nearest Residential CALIFORNIA Use 45 dBA Night -LAKE COUNTYO Outdoor: 55 dBA Ldn Nearest resident ial CALIFORNIA recepter These noise standards were generally developed for urban or suburban situations and, in -the case of all but the Oahu standar da, ior the mainland environment os well. Consequently, a factor which inust be considered in' viewing these various standards is the difference in the reduction of sound levels between residences.in. Hawaii and in the mainland resulting from different construction techniques and requirements. For.examplu, in establiL;hing their community noise exposure criteria, the Federal Environmental Protection Agency used an estimated ditterential of IF, dBA between outdoor and indoor noise levels. The U.S. Department of Housing.and Urban Development, on the other butid, used an estimated 20 dBA differential oetweeii indoor -and outdoor nuise, However, because of the differences in construction betwuen thelmainland and Hawaii, the actual reduction .of outdoor noise levels of local residences is anticipated to be closer to 9 dBA with estimates ranging from a low of 4 dBA to a high of 15 dBA. Furthermore, because of the rural nature of the Puna.District, it may not be reasonable to compare typical local environmen tal -3- -noise control regulations which have evolved for urban and suourban -environments. Tne typical nighttime ambient noise levels of the areas -Surrounding the geothermal exploration area are between 30'and 35 dBA 90 percent of the time. These levels are 10 to 25 dBA less than those found in quieter suburban communties. Thus, residents near the projects have become accustomed to a very quiet acoustical, --environment. The distance from noise source to listener is very great compared to most situations in heavily populated regions wh ere noise Conflicts have evoived. Thus, it is not reasonaole to attempt to .,control nuise levels at propert@ lines of the noise making operation to meet the allowable noise levles that have evolved in urban areas where relatively short distances exist to listeners. .Thermal gradients or inversions during times of stable. .-atmospheric conditions are apparently much more intense in'rural areas than urban or in*dustrial areas. Consequently, acoustical refraction phenomena or the-bending of sound rays, becomes a major effect which must be considered. (See Appendix A on Sound Attenuation.) GUIDELINES in conjunction with the various acceptaule noise standards and the factors specifically affecting the Puna environment, the Planning Department has developed the following noise level guidelines -for geotherm'al activities: -4- Thdt the acceptaole geothermal noi.se guidelines should be'at A ..level which reasonably assures that the-Environmental Protection Agency and U.S. Department of Housing and Urban. Development ,criteria for acceptable indoor-noise levels can be met. In generdl, the EPA and the HUD community noise level criteria estimate acceptable indoor noise as being between 40 to 45 dBA -during tlie day and 32 to 35;dBA at night. These levels take 7-into account conditions for satisfactory speech communication -during the day and acceptable sleeping conaitions at nig'ht. Tables 2 and 3 provides some insight into the relative noise levels as well as other studies which provide recommended sound levels for various spaces. That the sound level measurements should take place at the affected residential receptors. 'Given the existence of the thermal and wind gradients and :consequently ground inversion conditions,.it is extremely .,difficult to predict thte source noise levels necessary to insure --compliance with the noise guidelines. Consequently, until more -information is available about the incidence and duration of the 1round inversion conditions,.measurement of the sound levels at .the residential receptors will provide a rezsonable means of reveiwing 'and assessing the impact of geothermal noise on'the -residents of the areas surrounding the geothermal operations. 3. That, in conjunction apa apprec iation of-the ott ier guidelineso -5 TABLE 2 ..Loudness and Decibels Because hearing also varies widely between --individuals. what may seem loud to one person may -not to another. Although loudness is a personal judgment. precise ineasurement of suund is made --Pc)s!;IljlL! by use of the dccibel scale. This scale. -shown beluw. measures sound pressure or energy -21ccording to international standards Sound Levels and Hurnan Response Noise Level Common Sounds Ef feet (dB) Camel deck let operation 140 Painfully loud Air laid siren 130 -Jet takeoff (200 feet) 11hunderclap 120 Maximum vocal effort DtscothoQue Auto horn 43 leet) Pile drivers 110 Gailiage truck 00 Hcovy truck (50 feet) 90 Very annoying City tiallic Hearing damage ill hours) Alarne clock (2 teal) Hai( dryer so Annoying Noisy restaurant Freeway trallic 70 lewphone use difficult Man's voice (3 feet) Ait'coind-tioning unit (70 fact) 60 Intrusive Light auto traffic 50 Oulet (100 feel) Living loom bedroom 40 oulat office Library soft wwspef o5 feet) 30 Very quiet Broadcasting studio 20 .10 Just audible 01 Waring bogins 'this decibel (dtl) table compares some common Sounds and -shows how mey tank in potential ha-s to hearing. Note thall 70 dO IS the point at which noise begins to hami:@oarani; To the ear. each dB increase seems twice as loud. TABLE 3 RECOMMENDAilONS OF SOUND LEVELS IN VARIOUS SPACES XOSTM HARRIS BERANEK BERANEK LAWRENCE VAN OS ASIIRAZ DENISOV KRYTER TOKYO USSR BERANEK DOELLE WOOD RMINGER SWEDE 1950 1953, If$7 1%2 4%2 1%2 1%7 3970 1971 1971 1971 1971 1972 1"3 dbA dbA dbA dbk-. dbA dbA' dbA dbA dbA dbA dbA dbA 4bA dbA dbA RESIDENT Home Mrooot 35-41 35 JIS-45 zs IQ 25-11 40 33 34-47 35-43 33 3"2 25 Living; Room 35-411 3$ 40 35 30-40 40 is 3&47 40 33 Apanawrd 33-43 33-40 30 35-43 Is 34-47 U42 Role) 35-411 JIS-411 15-4 35-45 M is )"1 35-54 30-4 43 COMMERCIAL Restaurant W$S 53 is 40-60 *50 40-35 55 4.1-32 45-0 45-50 so Pn%oft Oftv 4@j so 3"s 1141 3"1 2541 44-4$ is IS-47 34-41 40-41 46 40 Gent" Office 45-1$ 406$1 40 3S-65 3044 35-0 x -4-32 45-si 65-55 Transportation 35-55 40 INDUSTRIAL Workshop Lisht 40-60 3.1-61 SS-63 Heavy 60-90 70 63 66-60 60-75 70 IDUCATION1 claisroare 35-40 is is 3"Q 30 )1-41 JIS 40 1947 is 15-45 38 3 Laboratory 1 40-30 40-30 40-30 47-" 45-50 42. Library 40-45 40 42-41 33-45 M 35-4S 40 36"7 40643 40-43 42 HEALTH Hospital 33-40 40 42 20-35 31 1"s 40 :j 3447 40 40,45 311 23-3 RECREATION Sairr-poa 45-60 30-60 sr.'"s Go 30 35-45 Go 60 46 G)mrwasium $5 40-30 33--60 41-S$ 46 AUDITORIUM AssemNy Hag 35-40 35 15-40 40-4s 30-40 3S 30-42 35-43 15-45 C'!=:,;h 315-40 40 40 3" is 23-35 40 is 34-42 3@-,;-) 151-40 )S-42 Canzer. Hja 3(@-33 30-33 .13-11 25-15 jo zs_il Z-js .11-30 :s-J5 30-35 J4 Court Room 40@45 40 40-4j 40-41 is 44 41. 3.4-40 35-40 [email protected] sw" 25-30 30 23-30 20-30 20 25-35 23 11.34 1-4-34 30 30 T% S14 -@o 23-10 30 30 :5-33 30 25-35 26 1.1-34 X-is is U-36 4w. 211-30 2J-30 2JI-35 23 21-14 is 23 %Ix fl:.2 TIscAa 3$-40 40 40 33 3S-45 40 40 40 3.1-40 is Le; T%ca:cr 30--)s 33 wis 2S 3" 33 30-34 10-33 34 OUTSIDE Rural Suburb 40-50 4$ Urban Beti. Arcils SOURM EPA. fqrarmwoti on Loveto q1&%*"a#,ww moo# ... (1974). the acceptable noise levels for geothermal development are as follows: a. That a general noise level of 55 dBA during daytime and 45 dBA at night not be exceeded except as allowed under b. For the purposes of these guidelines, night is defined as the hours between 7:00 p.m. and 7:00 a.m.; b. That the allowable levels for impact noise be 10 dBA above the generally allowed noise level should not be exceeded more than 10% of the time within any 20 minute period; C. That the noise level guidelines be applied at the existing .residential receptors which may be impacted by the geothermal operation; and d. That sound level measurements be conducted using standard procedures with sound level meters using the "A" weighting and "Slow" meter response unless otnerwise stated. SOME CONCLUDING NOTES The guidelines for allowable geothermal noise levels are intended to provide an interim basis for assessing geothermal activites. As more information is obtained and a better -understanding of both the noise levels and their impacts on the -environment and the climatic conditions affecting the Puna area, ..these guidelines should be amended. It is conceeded that there are problems associated with the proposed guidelines which will eventually require their amendment or the.adoption of long term guidelines as more information becomes .." navailable. For example, one problem with respect to noise ;measurements at the receptor as opposed to the source is -.distinguishing between noise sources once multiple geothermal ..operations come on line. Accurate measurements of the various. operations will have to be made to provide some baseline data. However, with the inversion conditions, it may be impossible to correctly ideatify the separate noise sources at the receptor. _.Another problein is tne cumulative impact. of noise from multiple sources. Sound levels incre'as.e on@a logarithmic basis when adde d together. That isr if there are two sources each with a 50 dBA @sound level, and if both are operating at the same timer th.e resultant suinidlevei will be approximately 53 dBA. Consequentlyr there is the potenLial case where all of the operators individually meet the noise guidelines, yet cumulatively, exceed it. Consequently, us part of the overall analysis of the impacts of geothermal activiLies in Puna, a noise monitoring program will be implemented when the well drilling, testing, and production -commence. This program should coordinate noise complaints with :noise measurements, meteorological conditions and the type df operation which occured at the well site. This data could then be used to determine if there is justification to invoke more stringent :noise mitigative procedures and/or devices, to reduce or increase the allowable residential receptor noise level guidelines as may be -appropriate, ana to establish Inaximuin source noise level guidelines. -7- -,APPENDIX A -SOUND ATTENUATION -As sound waves niuve through the atmospherej the energy of the @waves are weakened (attenuated) as the distance from the source Ancreases. The facturs affecting the amount or ievel of attenuation -include the distance -traveled, the frequency of the sound waves, 'th'e relative humidity, temperature and w.-*Lnd velocity6 in general, there are three distict conditions or combinations of,factors which affect the rate of attenuation of sound. These predicted sound propagation loss conditions (Darby, 1981) which may be applied to the Puna District are summarized as follows: Condition I - Cylindrical spreading based on 3 dB loss per .doubling of distance, which is the worst case. theoretically. This condition exists when compound sound velocity gradients in the atmoshpere cause the ducting of sound. Excess attenuation is due only to the molecular and anomalous phenoinen6. -Conditiun 2 - Synerical spreading based on 6 dB loss per doubling of distance plus excess attenuation for propagation througn air only. This condition exists when sound velocity gradients exist to nbendu sound r''ays over trqes ana other obstacles. Condition 3 - Spherical spreading based on 6 dB loss per 4doubling of distance plus excess attenuation for -propagation through air (Condition 2)1 plus ground -attenuation due to the absorption and scattering caused by txees and other foliage. @The positive sound velocity gradients or ground inversions, ..@Aentioned in Conditions 2 and 3 result when sound waves are 'xefracted or oent as they travel through' the atmospher .e These inversions are normally attributed to wind or thermal gradients. .(changes in wina velocity or temperature over a unit distance) or combinations uf.both. When--these ground inversions occur# they .usually take place about one hour before sunset and continue to -about one hour after.sunrise The conditions which contribu-te to. the ground inversions usually exist in the atmosphere from ground level to about 200 feet in altitude. When there are no ground inversions and ground-to-ground sound -transmission is in a straight line, large excess attenuation often --exists due to shielding by topographic features and buildings as well as due to absorption and scatter of sound by foliage (Condition 3). if a positive sound velocity gradient exists, then the sound -rays may travel on a large-arc passing above some of the .Obstruction!;, causiny much less.excess attenuation to be present ---(Conditi-on 2). it the gradient is strong enough, it is possible that the only sound attenuation experienced by the listener is. :.similar to a free space con(Ition; i.e., the result of spreading, --imolecular absorptiun and anomalous excess attenuation (Condtion 1). in his field tests in the Puna District, Darby (Darby, 1981) -found clear evidence of retraction or the bending 'of sound rays over obstacles due to positive thermal gradients or ground inversions. More specifically, in his comparison of the measured and predicted propagation loss data, Darby found:, -9- (1) The propagation loss may vary by 15 to 20 dB during a 24-hour period for a given distance between source and -listeaer..., indicating the generation and disappearance of --sound velocity gradients which bend sound rays over trees and other foliage (Conditions I and 2). (2) Usually propagation loss was not less than Condition 2. but -there are strong indications implying that energy,in the -lower irequencies (125 and 250 Hz) do experience a compound velocity gradient at times (Condition 1). (31 Por estimating noise levels in residential areas, a .:-reasonable average value for,souna propagation loss is t6 mse Condition 2 as a worst case understanding that when there are compound sound velocity gradients, noise levels in the low frequencies may be 5 to 10 dB greater.- These predicted sound propagation loss estimates were in part confirmed by the field measurements conducted by the 'Planning Department Statf on April 7, 1981. Although limited in scope and duration, the*.�e measurements confirmed the existence of the ground inversion conditions. more specifically, sound levels truin the Barnwell drilling operation were measurea in the Leilani Estates Subdivision which can only be explained by the Condtion'l estimates of sound propagation loss (Mo Iore/Nishimura, 1981a). _10- APPENDIX B DEFINITIONS ...The following definitions shall apply: -VA.Weighted sound Level" means a standardized decibel scale whose sensitivity varies with frequency the same way as the human ear' and which reflects man's responsiveness to sound. "Attenuation" weanS the lessening or weakening of sound pressure levels. -"Day - Night Sound Level (Ldn')" is the sound pressure level measure- ment which tak4s account of the fact that sounds are generally -more annoying at night. it is calculted like Leq but with 10 dBA added to sound levels occuring between 10:00 p.m. and.1:00 a. m. '"Daytime" means the time period from 7:00 a.in. to 7:00 p.m. of the same day "Decibel" ineans one-tenth of a bel. A unit of sound level.. A. dB an abbreviation for decibels. B. dBA an abbreviation for A-weighted souna,level expressed in decibels Sound Level (Leq)" is the sound pressure le.ve@l which over a given peri6d of timL- would contain the same noise energy as the time varying sound level being described; ie., the average energy of fluctuating noise levels. "Excessive Noise" means any sound or sequence of dounds to which an individual is exposed and which exceeds the allowable noise level more tnan 10 percent of the time in any 20-minute period. For the purpose of this definition, any sound having a duration :2ess than one second shall be assumed to last one second. .-,"Impulse Noise" means any sound with a rapid rise and decay of sound. pressure level, lasting less than one second, caused by sudden ..contact between two or more surfaces, or caused by a sudden release of pressure, including but not limited to any hammeringr pile driving, and explosion. "Fast" meter response shal 1 be used to weasure these types of noise. Nighttime" means the time period from 7:00 p.m. to 7:00 a.m. of the following day. --"Noise" means any sound that may produce adverse-physiological,or -psychological effects and/or interfere with individual or group ,activities such as but not limited to communication, work, iesti, recreation or sleep. -mNoise Level" means the weighted sound level. -wSound" means a fluctuation in air pressure which stimulates the -human nervous syst,ems through the ear, eardrums, and connecting' -nerves. OSound Level Meter" means an instrument or combination of. instruments, which meets or exce.eds the requirements fbr*Type I or Type II sound level meter as specified in American National Standard Ins titute (ANSI) Specification for Sound Level Meters S1.4-1971 or IEC 179 or IEC 123 or their.most recent approved .revisions. "Sound Pressure Level (Decibel)" means 2-0 times the logarithm to the base 10 of the ratio of the meaured sound pressure to the reference sound 'pre*ssure of 0.0002 cynes per square cen timeter or 20 micropascals. -12- Reference -1. B & K Instrumetits, Inc.; "Community Noise measurements" 2. B & K Instrumentsp Inc.; "Sound..Measurementw 3. Burgess, John C.; Hawaii Energy Resource overview, Volume 1; OPotential Noise Issues of Geothermal Development in Hawaii"; .June 2980 4. Darby, Rondid A.; "Evaluation of Predicted Noise Levels in Residential Areas.Near-Drilling and Testing for Geothermal Wells at Puna, 11dwaii, Report to Thermal Power Company, March 1981 5.@ Keyes, Dale L; The Urban Institute uLand Development and the .-Natural Environment: Estimating Impacts"; April 1976 6. Moore, William and Nishimura, Brian; County of Hawaii Planni ng Department Memorandum, "Moditoring Geothermal Drilling Activity, Barnwell Special Permit No. 471";-April 1981'(a) -7. Moore, William and Nisnimura, Brian; County of Hawaii Planning DeDartment Memorandum, "Geothermal Noise Level Standards and -Recortunendations"; April 1981(b)' 8. Reynolds, Robert L. and Sanderland, Donald L.; County of Lake, Caiifornia, Air Pollution Control District, Personal Communication; may 1981 -9. Shiraishi, Bernard and Anamizu, Thomas, State of Hawaii, Department of Health, Noise and Radiation Branch, Personal -Communication, April 19di 10. State of Hawaii, Public-Health Department Chapter 44B, Department of Health; wCommunity Noise Control for Oahun; April 1976 -13 3 6668 '14102 9803