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recharge to the local aquifer is considered insignificant. The proposed project will not significantly impact the groundwater. 2 · FINDINGS The mitigation measures contained in the Mitigation Monitoring Program as Mitigation Number 22 through 28 have been required in, or incorporated into, the project and those mitigation measures mitigate or avoid the significant environmental effects identified in this EIR and outlined above. Substantial evidence supporting this finding is contained in the record at pages 4-30 through 4-34 of the Revised Draft EIR and Technical Appendices, Volume I, Appendix E, p. 15. D. NOISE 1 · ENVIRONMENTAL EFFECTS Helistop A helistop is to be included in the development. The loudest types of helicopters that will likely use the facility are the Augusta 109 and the Sikorsky S-76 helicopter. Three other types of aircraft which could use of the facility are the Boelkow 117, the Bell 206L, and the McDonnell Douglas 500. The project noise level of the loudest of these aircraft, the Augusta 109, is between 91 and 92 dB at a 1,000 foot approach. When the approach attitude is 450 feet, projected noise levels would increase by about 5 dB. Operation of the helipad will contribute to neighborhood noise levels when in operation. Short-Term Construction Noise Construction noise will occur as a result of the development of the proposed project. Although construction noise represents a short-term impact on ambient noise levels, construction equipment and construction activities can generate high noise levels. Construction equipment noise comes under the control of the Environmental Protection Agency's Noise Control Program (Part 204 of Title 40, Code of Federal Regulation). On the construction site, the use of pile drivers presents the greatest intensity potential for construction noise impacts. Noise associated with the use of pile drivers, however, could reach as high as 105 dBA at 50 feet. These noise levels are based upon worst-case conditions. Actual noise levels on the site could be much less. These noise impacts, while significantly loud, represent a short-term noise impact. Due to the preliminary stage of the project, however, it is not possible to determine whether the use of pile drivers will be necessary for this project. If pile drivers are not needed, the noise levels produced will be substantially less than pile driving equipment. 14