4.13 Noise
South Carlsbad North
The closest residences to this receiver site are 550 to 750 feet from the beach area. Most of the beach
area where sand would be distributed is not directly visible because of the topography. Line of site
construction equipment noise would be more than 20 dBA less at the residences than at the beach, and
would not likely be discernable above the traffic noise from Carlsbad Boulevard. The noise impact would
not be significant. There is no potential impact at this site from dredge or booster pump noise.
Batiquitos, Leucadia, and Solana Beach - Bluff Receptors
Sensitive noise receptors at these three sites are residences located on bluffs above the receiver sites.
Ambient surf noise levels at these homes are estimated at 63-66 dBA Leq. The topography and slightly
greater distance from these homes to the sand replenishment area, when compared with the beach front
homes at South Oceanside, Moonlight Beach, etc., would maximum reduce noise levels to approximately
70 dBA for short peak noises, and 60 dBA Leq for an hourly average.
Impacts would be similar to those at the sites with beach front homes. The peak construction noise event
would be a diesel engine under load, sounding a backup alarm while close to a house. This event would
be heard by residents. The average noise change would be noticed because of a difference in character
from the ambient surf noise, and because the overall average noise level would be anticipated to increase
2 to 4 dBA. At nighttime, when work would occur within 200 feet of a residence, the change in noise
environment could be anticipated to disturb the sleep of some residents. While closing the windows would
reduce the noise level, the change in the volume and character of the noise may disturb sleep as much as
an increase in noise would. The nighttime construction noise would be an adverse impact. However, the
impact would be less than significant because residents would be notified at least one week in advance of
the work near their homes, and the work would last no longer than three consecutive days within a distance
where the noise might cause a sleep disturbance.
The approximate minimum distance from the dredge to bluff top sensitive receivers is 4,000 feet, which
would occur at the Batiquitos receiver site. At that distance, noise attenuation from a point source would
be approximately 43 dBA. With a 90 dBA source noise at the dredge, the resulting noise level at bluff top
residences would be approximately 47 dBA. With the normal prevailing onshore wind, noise levels may
seem slightly greater. However, a noise level of 47 dBA would be much less than the normal ambient noise
level from wave activity on the beach, and noise from the dredge would not be expected to be audible.
Regional Beach Sand Project EIR/EA
Page 4.13-5
99-69\sect-04.13.wpd 7/19/00
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