HomeMy WebLinkAbout- - PA 0918 Supplemental Memo - 8/3/2010CITY COUNCIL
SUPPLEMENTAL MEMORANDUM
MEETING DATE: AUGUST 3, 2010
SUBJECT: REQUEST FOR REHEARING OF PLANNING APPLICATION PA -09-18: MASTER PLAN
FOR A MIXED USE, 53 -UNIT, 4 -STORY, SENIOR HOUSING AND 4,980 SQ. FT. RETAIL
COMMERCIAL PROJECT AT 845 BAKER STREET
DATE: JULY 28, 2010
FOR FURTHER INFORMATION CONTACT: MEL LEE, SENIOR PLANNER
(714) 754-5611 (mlee@ci.costa-mesa.cams)
Attached for your reference is the noise study prepared for the Baker Street Lofts Project
at 801 Baker Street referenced in Mayor Pro Tem Wendy Leece's rehearing request.
41-1-
Mtl LEE, AICP
Senior Planner
Attachment: 1. Noise Study
Distribution: City Manager
Asst. City Manager
City Attorney
Dev. Svs. Director
Public Services Director
Transportation Services Manager
City Clerk (2)
Staff (4)
Planning Staff (8)
File (2)
Eric A. Nelson
1234 E. 17th Street
Santa Ana, CA 92701
KIMBERLY B DT, AICP
Development Svs. Director
Jan R. Hochhauser, AIA
Hochhauser Blatter Architecture + Planning
122 E. Arrellaga Street
Santa Barbara, CA 93101
Arthur M. May, AIA
Senior Vice President
USA Properties Fund
2440 Professional Drive
Roseville, CA 95661-7773
Larry McElwain
Architectural Development Manager
USA Properties Fund
2440 Professional Drive
Roseville, CA 95661-7773
Michelle Keldorf
USA Properties Fund
3950 Paramount Blvd., Suite 101
Lakewood, CA 90712
Peter Buffa
2824 Nevis Circle
Costa Mesa, CA 92626
File: 080310PA0918Su Memo Date: 072810 Time: 8:30 a.m.
NOISE STUDY
Baker Street Lofts
Costa Mesa, California
Prepared for:
RED MOUNTAIN RETAIL GROUP
Prepared by:
PCR SERVICES CORPORATION
March 2007
r
TABLE OF CONTENTS
Page
1. INTRODUCTION.....................................................................................................................1
1.1
Purpose............................................................................................................................I
1.2
Project Description..........................................................................................................1
2. NOISE ANALYSIS..............................................................................:....................................3
2.1
Noise Descriptors............................................................................................................3
2.1
City of Costa Mesa Requirements..................................................................................3
2.2
Existing Noise Environment...........................................................................................4
2.3
Sound Insulation Requirements......................................................................................5
3. NHTIGATION MEASURES.....
3.1
Exterior Construction......................................................................................................7
Red Mountain Retail Group
PCR Services Corporation
P ag,
Balzer Street Lofts
March 2007
F
LIST OF FIGURES
'Figure
PaLye
Figure1 Project Site Plan...........................................................................................................2
Baker Street Lofts
Red Mountain Retail Group March 2007
PCR Services Corporation
Page
LIST OF TABLES
Table Page
Table 1 Measured Ambient Noise Levels at Project Site ...........................................
Baker Street Lofts
Red Mountain Retail Group March 2007
PCR Services Corporation
Page
1. INTRODUCTION
1.1 PURPOSE
The purpose of this noise study is to:
a. Measure and quantify the existing ambient noise environment at the proposed Project
site;
b. Evaluate the sound attenuation requirements of the proposed Project exterior building
envelope with respect to the City of Costa Mesa's Noise Study requirement as stated
in SoBECA Urban Plan adopted April 4, 2006 (Page 19); and
c. Recommend, if needed, noise mitigation measures required to meet the interior sound
level standard of 45 dBA CNEL as specified under SoBECA Urban Plan.
1.2 PROJECT DESCRIPTION
Red Mountain Retail Group proposes to construct the Baker Street Lofts (Project) in the
City of Costa Mesa: The proposed Project would add 21 -unit multi-level residential lofts above
the existing single -story commercial building. The project site plan, shown on Figure 1 on page
2, is bounded by Baker Street to the north, Century Place to the east, and the 73 Freeway running
diagonally to the southwest.
Red Mountain Retail Group Baker Street Lofts
March 2007
PCR Services Corporation
Page
. y
� «>
_a _ Mountain Retell Group, zzGoogle Earth, _
Ee]
Si Plan S owbig
Noise Monitoring Locations
:
_r _,
2. NOISE ANALYSIS
2.1 NOISE DESCRIPTORS
The decibel (dB)' is a conventional unit for measuring the amplitude of sound because it
accounts for the large variations in sound pressure amplitude and reflects the way people
perceive changes in sound amplitude. When describing sound and its effect on a human
population, A -weighted (dBA) sound levels are typically used to account for the response of the
human ear. The term "A -weighted" refers to a filtering of the noise signal in a manner
corresponding to the way the human ear perceives sound.
Community noise levels usually change continuously during the day. The equivalent
sound level (Leg) is normally used to describe community noise. The Lea is the equivalent
steady-state A -weighted sound level that would contain the same acoustical energy as the time -
varying .A -weighted sound_ level during the same time interval. For intermittent noise sources
such as music, the maximum noise level (Lma.,) is normally used. The Lmax sound level
represents the maximum noise level measured during the measurement.
Another noise metric, commonly used for land use planning and is also used by the City
of Costa Mesa, is the Community Noise Equivalent Level (CNEL). The CNEL adds a 5 dBA
penalty to noise occurring during evening hours from 7:00 P.M. to 10:00 P.M., and a 10 dBA
penalty to sounds occurring between the hours of 10:00 P.M. to 7:00 A.M. to account for the
increased sensitivity to noise events that occur during the quiet late evening and nighttime
periods. Thus, the CNEL noise metric provides a 24-hour average of A -weighted noise levels at
a particular location, with an evening and a nighttime adjustment, which reflects increased
sensitivity to noise during these times of the day.
2.1 CITY OF COSTA MESA REQUIREMENTS
The SoBECA Urban Plan requirement with respect to noise study for the Project is stated
as follows:
• The residential interior noise levels shall be 45 CNEL or less; and
All sound levels, measured in decibel (dB), in this study are relative to 2x10-5 N/mz
Red Mountain Retail Group Baker Street Lofts
March 2007
PCR Services Corporation
Page
Noise Study
• The residential exterior noise levels in private open space areas shall be 65 CNEL or
less. The residential exterior noise standards; however, are not applicable to multi-
family residential development such as the Baker Street Lofts.
• The City of Costa Mesa Noise Ordinance (Section 13-281) provides interior noise
standard of maximum noise level of 55 dBA (for nighttime hours between 10 P.M.
and 7 A.M.). The standard also states that for noise consists of music, the noise
standard shall be reduced by 5 dBA. As applicable to this Project, the maximum
interior noise level due to music shall be 50 dBA.
2.2 EXISTING NOISE ENVIRONMENT
The existing noise environment at the proposed Project site is comprised primarily of
auto traffic on the adjoining 73 Freeway, nearby local streets including Baker. Street; adjacent
commercial operations including the existing nightclub (The Shark Club) on the abutting
property (841 Baker Street), as shown on Figure 1. To quantify the existing noise. environment,
long-term noise measurement was made from Saturday February 17 to Tuesday February 20,
2007. The ambient noise measurement extended through the weekend to include noise levels
from operation of adjoining nightclub, which normally operates on weekend during the late
nighttime hours.
2.2.1 Measurement Procedures
Noise measurements were conducted using Larson -Davis 820 Precision Integrated Sound
Level Meter (SLM). The Larson -Davis 820 SLM is a Type 1 standard instrument as defined in
the American National Standard Institute (ANSI) SIA. All instruments were calibrated and
operated according to the applicable manufacturer specification. The microphone was placed at a
height of 5 feet above the roof elevation of the existing commercial building with direct line -of -
sight to the 73 Freeway, Balser Street, and the nightclub. The sound level meter was setup to
collect the hourly average noise level (Leq) used to calculated the 24-hour CNEL and the
maximum noise level (Lmax) to document noise generated by the nightclub (during the late night
hours).
2.2.2 Measurement Results
Table 1 on page 5 presents the existing noise environment in the project vicinity. Based
on field observation and measured sound data, the existing noise environment in the vicinity of
the project site is controlled mainly by auto traffic and noise from the adjacent nightclub
especially during the late night hours when the nightclub is in operation. As indicated on Table
1, the Project site is currently exposed to exterior noise level up to. 68.4 CNEL,
Baiter Street Lofts
Red Mountain Retail Group
March 2007
PCR Services Corporation
Page
/D
Date / Time
Saturday 2/17/07 —
12 A.M. to 12 A.M.
Sunday 2/18/07 —
12 A.M. to 12 A.M.
Monday 2/19/07 —
12 A.M. to 12 A.M.
Tuesday 2/20/07 —
12 A.M. to 10 A.M.
Table 1
Noise Study
Measured Ambient Noise Levels at Project Site
Nighttime L.,,,
24-hour CNEL
Mainly due to nightclub operation
(dBA)
(dBA)
Notes
68.4
75 to 83
Nightclub Open
(10 P.M. Fri. to 3 A.M. Sat.)
68,2
72 to 82
Nightclub Open
(10 P.M. Sat. to 3 A.M. Sun.)
65.5
64 to 71
Nightclub Closed
(10 P.M. Sun to 3 A.M. Mon)
e
61 to 67
Nightclub Closed
(10 P.M. Mon to 3 A.M. Tue)
° Measurement was less than 24 hours.
Source: PCR Services Corporation, 2007
During the late night hours (between 10 P.M. and 3 A.M.) when the nightclub is in
operation (i.e.,- Friday and Saturday nights), the maximum noise level (Lmax) of 83 dBA was
recorded at the Project site., which is up to 22 dBA higher than the nights when the night club is
closed (i.e., Sunday and Monday nights).
2.3 SOUND INSULATION REQUIREMENTS
In order to meet the SoBECA Urban Plan interior noise limit of 45 dBA CNEL the
proposed building exterior envelope must provide a minimum of 24 dBA exterior/interior noise
reduction. This translates to a minimum Sound Transmission Class (STC) STC 34 rating for
exterior construction including; building fagade, windows, doors, and roofs.
The City noise standard of 45 CNEL interior noise level is normally adequate for general
environmental noise sources, such as traffic or other continuous and steady state noise sources
(e.g. building mechanical equipment). However; as mentioned in the previous section, the
Project site is also exposed to short term but significant noise levels due to operation of the
adjacent nightclub. The nightclub nighttime operation noise level was measured up to 83 dBA at
the future site of the proposed residential building. The high noise level generated by the
nightclub during the late night hours could be a potential noise impacts to interior environment
of the proposed Project. Furthermore, the nightclub related activities, as reported by Red
z Sound Transmission Class, STC, is a single number acoustic rating for building construction, indicating the
noise reduction performance. The higher STC rating represents a higher acoustic performance or higher noise
reduction
Red Mountain Retail Group Baker Street Lofts
PCR Services Corporation March 2007
Page
Noise Study
Mountain Retail Group, noise generation is primarily from musical instruments, bands and
broadcast stereo systems with low bass (low frequency). As such the Project should also comply
with the City of Costa Mesa Noise Ordinance Section 13-281 (described in Section 2.1 above),
that is, reduce the exterior noise from the adjacent Shark Club (83 dBA maximum noise level) to
the interior of the residential units (50 dBA maximum noise level). The Project exterior
walls/windows and doors construction, therefore, should provide sound attenuation, of no less
than 33 dBA or minimum STC 43 rating.
Red Mountain Retail Group Balser Street Lofts
March 2007
PCR Services Corporation
Page /;
3. MITIGATION MEASURES
3.1 EXTERIOR CONSTRUCTION
The following mitigation measures are recommended to meet the City's sound insulation
requirements. As the project is in preliminary design phase, final construction materials are not
yet selected. Therefore, mitigation measures are specified in terms of acoustic performances.
1. West and North Facades of Residential Units facing the Shark Club:
a. Wall — Minimum STC 43. Typical exterior wall construction, such as stucco
on wood studs and gypsum wall panels, would meet STC 43. If other type of
wall system is use, project design specification shall include acoustic data
indicating the specified system meet minimum STC requirement.
b.W indows — Minimum STC 43 rating. Project design specification shall
include manufacturer's acoustic data indicating the specified window
assemblies meet minimum STC requirement.
c. Doors — Minimum STC 38. Acoustic rated assembly. Project design
specification shall include manufacturer's acoustic data indicating the
specified door assemblies meet minimum STC requirement.
2. East and South Facades of Units not facing the Shark Club:
a. Wall — Minimum STC 34. Typical exterior wall construction, such as stucco
on wood studs and gypsum wall panels, would meet STC 34. If other type of
wall system is use, project design specification shall include acoustic data
indicating the specified system meet minimum STC requirement.
b.W indows — Minimum STC 34 rating. Project design specification shall
include manufacturer's acoustic data indicating the specified window meet
minimum STC requirement.
c. Doors — Minimum STC 29. Solid core wood or insulated metal door with a
full set of acoustics seal would meet this requirement.
Red Mountain Retail Group Baker Street Lofts
March 2007
PCR Services Corporation
Page 13