HomeMy WebLinkAbout8.2 Attch 4 Salter & Assoc Noise Study C h a r l e s M S a l t e r A s s o c i a t e s I n c
23 March 2006
Shandy Cole
Fountainhead Montessori
shandy ar,fountainheadmontessori.or�
Subject: Montessori School at 6665 Arnador Plaza -- Dublin, CA
Proposal for Acoustical Consulting Services
Dear Sandy:
We understand that the existing Montessori preschool located at 6901 York Street has
been forced to relocate from its current address so that the building may be used by the
school district for adult education classes. The new preschool building is located in an
office complex adjacent to the [-680 freeway on ramp. The City of Dublin has required
that an acoustical report be prepared to assess any potential noise impact the preschool
may have on the neighboring office buildings. To assess this impact, we conducted
acoustical measurements at both locations. This letter summarizes our analysis of the
projected noise from the preschool to the surrounding office buildings.
In summary, we would not expect the preschool outdoor activities to create a noise
disturbance at the adjacent office building for the following reasons:
I. The traffic noise levels far exceed the noise generated by children playing.
2. The children are playing outside a small percentage of the day.
ACOUSTICAL,CRITERIA
The City of Dublin Noise Ordinance prohibits the generation of unreasonable noises.
These are defined as "any loud or disturbing, or unnecessary, or unusual, or habitual
_ noise or any noise, which annoys or disturbs, or injures or endangers the health, repose,
peace or safety of any reasonable person of normal sensitivity present in the area."
MEASUREMENTS
On 21 March 2006, we deployed a sound level meter at the adjacent office building to
6665 Amador Plaza. The meter recorded noise levels between the hours of 9:00 a.m. to
12:00 p.m. The ambient noise level was 72 dBA consistently for those three hours.
The noise level is controlled by vehicular traffic along highway I-680.
ATTACHMENT 4
Shandy Cole
23 March 2006
Page 2
The selected time of measurement corresponds to the anticipated time the children
would be outside for recess play. During this time, we visited the existing preschool to
record actual noise levels of children at play outside. We set up a sound level meter
approximately 50 feet from the centroid of activity and measured the noise for 15
minutes to get an average noise level. The average noise level of children at play was
64 dBA with individual events such as yelling ranging from 71 dBA to 77 dBA.
ANALYSIS
The edge of the new project playground is approximately 50 feet from the facade of the
adjacent office building. For this analysis, we assume that children are uniformly
distributed about the playground during recess. The centroid of these children would be
an additional 50 feet from the building. The increased distance between the center of
the children playing and the fayade reduces the expected noise levels at the office
building. Our calculations indicate that noise levels of children playing could be
reduced as much as an additional six decibels to 58 dBA.
The proposed project site noise levels exceed the average noise produced by children at
play by up to 14 decibels. In acoustics, a noise level that is 10 decibels below another is
almost inaudible. Therefore, the noise of children playing would approach inaudibility
compared to the noise from traffic along the highway.
The preschool currently has set times that children are playing outside. These times are
as follows:
8:30 a.m. To 9:00 a.m.
11:00 a.m. To 11:45 a.m.
12:45 pan. To 1:45 p.m.
4:00 p.m. To 5:00 p.m.
We do not expect the play schedule to change after preschool relocates. The future
noise from children playing compared to the existing traffic noise is negligible.
Therefore, we do not anticipate the preschool outdoor activities impacting the adjacent
office building.
This concludes our comments on the subject project.
CHARLES M. SALTER ASSOCIA'rES, INC.
AA1—
Eric A. Yee
Principal Consultant
EAY/eay
P:\CSA_Projects\y2006\06-0146_EAY_Fountain Head Morrtessori\Coiresp Out\23mar_eay_report pd£doc