4.13 Noise
be used in bulldozers, loaders, forklifts, and cranes, as this equipment may be required. Diesel engines may
also be used to drive booster pumps when needed to convey the sand slurry over distances greater than
10,000 feet.
Diesel engine noise levels for construction equipment are quoted in the literature as 85-90 dBA at 50 feet
from the engine. These are noise levels that may occur when the engine is under a heavy load; that is the
equipment is pushing, lifting, etc. Noise levels from the engine are less than 85-90 dBA when the
equipment is moving from one location to another without working, or when the equipment is idling. A
typical duty cycle for a piece of construction equipment includes all three phases: working, moving and
idling. Therefore, the average noise levels over a period of time would be less than 85-90 dBA.
Beach maintenance was in progress when site visits were made to the Mission Beach and Imperial Beach
receiver sites in July 1999. In both cases, the equipment in use were Case 621B wheeled loaders. Two
of the machines were equipped with buckets, one with a rake. Working noise levels for this machine were
measured, and thenambient background noise was mathematically removed, to generate an estimated noise
level of 74-77 dBA at a distance of 50 feet. Idling noise levels are estimated at 65-68 dBA at 50 feet.
These may be considered typical noise levels for all beach equipment that may be used for the project.
It is also noted that construction equipment are equipped with mandatory backup alarms, and sand
distribution requires construction equipment to change direction frequently. Therefore, the diesel engine
noise would be accompanied at some times by the backup alarms.
The diesel engines used on the dredge would be much larger than those used in construction equipment,
and the noise generated would be greater. However, the engines would be housed in structures which
would reduce the noise, and noise levels exceeding 90 dBA at a distance of 50 feet would not be
anticipated.
The diesel engine used to drive a slurry pump would also be larger than one used inconstructionequipment.
These engines normally are provided in an enclosure that will provide noise reduction. A noise level of 70
dBA at 50 feet is assumed for purposes of noise analysis (Department of the Navy 1997b).
Page 4.13-2
Regional Beach Sand Project EIR/EA
99-69\sect-04.13.wpd 7/19/00
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