 <br /> <br />Adding an insulated elbow for the air discharge that will direct the warm air discharge <br />from the generator room downwards towards the ground. For the best results the ground <br />under the elbow should not be a hard reflective surface such as asphalt or concrete; but <br />should be lawn or landscaping. The noise attenuation for this elbow is supported by data <br />from ASHRAE for the insulated elbows of the appropriate dimensions. <br /> <br /> <br /> <br /> The noise attenuation for the GT-201-5100 critical grade exhaust muffler was increased <br />from 30 dBA to 35 dBA. An examination of data from GT for this model of muffler <br />indicates that 35 dBA is the more accurate attenuation factor. <br /> <br /> <br /> <br /> A change was made in how noise attenuation factors were assigned for the air intake <br />noise that would be experienced at the nearest residential property to the west. The <br />“building factor” was reduced by 7 dBA and this same amount was added to the “noise <br />control” category. This change reflects the fact that the noise reduction from the air <br />intake plenum belongs more properly in the “noise control” category than in the <br />“building factor” category but has no effect upon the overall noise impacts. <br /> <br /> <br /> <br />The revised report corrected a misprint for the” Building factor” noise attenuation for air <br />intake impacts at the south residential property line. The figure of -10 dBA should not <br />have been in the table. The dBA impacts remain unchanged as the total for all noise <br />attenuation (Build Factor + Noise Control) does not change (it is -17 dBA in both <br />reports). <br /> <br /> <br /> <br />One error does remain in the revised “Receiving Property-South” table: The dBA impact <br />at the south residential property for exhaust noise should have been calculated as 31 dBA <br />not the 36 dBA shown in the table. However, due to the fact that noise levels add <br />logarithmically there will be no change in the total impact level of 45 dBA. <br /> <br />The emergency generator, with the additional mitigation measure of an insulated hood for the air <br />intake will meet the City’s 45 dBA standard. <br /> <br />The applicant provided calculations of RF emissions that would be received by a person at <br />ground level. Their calculations follow standard formulas. The RF power density calculations <br />performed indicate the maximum power exposure for a person standing at ground level and <br />indicate that the maximum power density for a person would be less than 1.3% of the FCC <br />standards for the general public. The results are consistent with the reported output power of the <br />antennas. <br /> <br /> <br />CONCLUSIONS <br /> <br />The information in the applicant’s proposal is sufficient to determine that the NIER impacts of <br />the project fall well within Federal and City regulatory limits. The applicant detailed noise <br />mitigation measures that will enable the proposal to meet the City’s noise ordinance and stricter <br />limits agreed to as part of the CUP process. No additional conditions need to be applied to <br />mitigate either the project’s sound pressure levels or its NIER emissions. <br /> <br />