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San Joaquin County Community Environmental Setting,Impacts,and Mitigation Measures _ <br /> Development Department Noise <br /> Table 1.1-5. Construction Noise <br /> Entered Data: _ <br /> Construction Condition:Site leveling <br /> Source 1: Scraper-Sound level(dBA)at 50 feet' = 85 <br /> Source 2:Bulldozer-Sound level(dBA)at 50 feet' = 81 _ <br /> Source 3: Heavy Truck-Sound level(dBA)at 50 feet' = 84 <br /> Average Height of Sources-Hs(feet) = 10 <br /> Average Height of Receiver-Hr(feet) = 5 — <br /> Ground Type(soft or hard) = Soft <br /> Calculated Data: <br /> All Sources Combined-Sound level(dBA)at 50 feet = 88 <br /> Effective Height(Hs+Hr)/2 = 7.5 <br /> Ground factor(G) = 0.62 <br /> Distance between Source and Geometric Attenuation Ground Effect Attenuation Calculated Sound Level — <br /> Receiver(feet) (dB) (dB) (dBA) <br /> 50 0 0 88 <br /> 100 -6 -2 81 <br /> 200 -12 4 73 - <br /> 300 -16 -5 68 <br /> 400 -18 -6 65 _ <br /> 500 -20 -6 62 <br /> 600 -22 -7 60 <br /> 700 -23 -7 58 _ <br /> 800 -24 -7 57 <br /> 900 -25 -8 56 <br /> 1000 -26 -8 54 — <br /> 1200 -28 -9 52 <br /> 1400 -29 -9 51 <br /> 1600 -30 -9 49 _ <br /> 1800 -31 -10 48 <br /> 2000 -32 -10 46 <br /> 2300 -33 -10 45 — <br /> 3000 -36 -I1 42 <br /> Note: This calculation does not include the effects,if any,of local shielding from walls,topography,or other <br /> barriers which may reduce sound levels further. <br /> Based on 40%utilization factor resulting in Lro being 4 dB less than L.;calculations based on FTA 1995. <br /> Residences are located within about 500 to 1,500 feet of construction and _ <br /> reclamation areas. Although the noise ordinance exempts construction activities <br /> from noise ordinance limits between the hours of 6:00 a.m. and 9:00 p.m.,this <br /> analysis indicates that residences in the project area could be exposed to <br /> construction or reclamation noise exceeding the daytime noise standard between — <br /> the hours of 9:00 p.m. and 10:00 p.m. and noise exceeding the nighttime standard <br /> between the hours of 10:00 p.m. and 7:00 a.m. This impact is therefore <br /> considered to be significant. Implementation of the Mitigation Measure N-1 — <br /> would reduce this impact to a less-than-significant level. <br /> DeSilva Gates Quarry Project <br /> Draft Environmental Impact Report 3.J-10 <br /> JSS 05105.05 <br />