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<br />• forested areas, causing contrasts in both surface color and texture. Figures 7-32 and <br />7-33 provide views of existing pipeline disturbance along the proposed project <br />pipeline route. <br />7.13 NOISE <br />• <br />The project area is located in an undeveloped, rural area that is relatively <br />undisturbed by human activities. At present, the project area is used primarily by <br />livestock and wildlife. Typically, noise level values for rural areas are 30 to 50 A- <br />weighted decibels [dB(A)] with an LSp value of 37 (Cuniff 1977). (The weighting of <br />noise levels is done to simulate levels perceived by the human ear. The LSo value is <br />the median noise level that is exceeded 50 percent of the time.) Noise monitoring <br />conducted near the Piceance Site revealed that noise levels vary between 35 and 45 <br />dB(A), depending on wind speed (BLM 1982). For the sake of comparison, the noise <br />levels required to adequately protect human health and welfare are shown in Table <br />7-8. <br />Table 7-8 Summary of EPA Noise Levels Identified as Requisite to Protect Public <br />Health and Welfare with an Adequate Margin of Safety. <br />Level Effect Area <br />LeglZ,l < 70 Hearing loss All areas <br />dB(A) <br />Ld„ < 55 Outdoor Outdoors in residential areas and farms and <br />dB(A) activity other outdoor areas where people spend <br /> widely varying amounts of time, and other <br /> places in which quiet is a basis for use. <br />LeQI_,I < 55 Outdoor areas where people spend limited <br />dB(A) amounts of time, such as school yards, <br /> play rounds, etc. <br />L~„ < 45 Indoor activity, Indoor residential areas <br />dB(A) interference, <br /> and annoyance <br />Ld„ < 45 Other indoor areas with human activities, <br />dB(A) such as schools, etc. <br />Source: EPA (1974) <br />C: <br />" The hearing loss level identified here represents annual averages of the daily <br />level over a period of 40 years. (These are energy averages, not to be confused <br />with arithmetic averages.) <br />L=alza~ Equivalent sound level fora 24-hour period <br />L~„ Day-night sound level [Noise occurring at night (10 PM to 7 AM) is considered to <br />have more of an impact than noise during daytime hours.] <br />American Soda, L.L.P. <br />Commercial Mine Plan <br />August 18, 1998 <br />7-48 <br />