HomeMy WebLinkAbout3184; CANNON ROAD WEST; INITIAL NOISE STUDY; 1999-03-169,
Investigative Science and Engineering
3511 Camino Del Rio South, Suite 302 Phone/Fax: 619-640-9379 /619-640-0763
San Diego, CA 92108-4003 wwwise-advantage.com
March 16, 1999
MAR 17 1999
Ms. Sherri Howard ENGINEERING
City of Carlsbad - Engineering Dept. DEPARTMENT 2075 Las Palmas Drive
Carlsbad, CA 92009-1576
Re: Cannon Road West Project Initial Noise Study - (ISE Report #99-007)
Dear Ms. Howard:
At the request of the City of Carlsbad, Investigative Science and Engineering
(ISE) has performed an initial site survey of riparian habitat along the proposed Cannon
Road extension alignment located in Carlsbad, California. The purpose of the study
was to determine existing noise levels and acoustic propagation conditions within the
project area and recommend mitigation based upon anticipated construction activities.
The results of that survey are presented in this letter report. -
Introduction and Definitions
Site Characterization
The Cannon Road West Project is located in the City of Carlsbad in San Diego
County, California (refer to Figure 1). This project will extend Cannon Road
approximately 2 miles east from its terminus at 1-5 to Camino Real. The Cannon Road
extension consists of two bridge crossings and traverses through and adjacent to
habitat for the federally endangered/threatened least Bell's vireo, southwestern willow
flycatcher, and California gnatcatcher.
The predominate land use of the project area is undisturbed open space.
Wetlands originating from the Agua Hedionda Lagoon and Agua Hedionda Creek are
located adjacent to the north and commercial developments are present to the west.
Elevations for the project area have been altered due to construction activities;
however, pre-construction elevations range from approximately 100 feet above mean
sea level (MSL) along the terrace over looking Agua Hedionda Lagoon down to
approximately 5 feet above MSL along the Agua Hedionda
Qb 19
Figure 1: Project Alignment Area Map (Thomas Guide Pages 1126,1127, and 1107) :
- __•(
Acoustical Definitions
Airborne sound is a rapid fluctuation of air pressure above and T below -
atmospheric levels. The loudest sounds the 'human ear can hear conformably is - -
approximately one trillion (a one with 12 zeros following it) times the écousticenergy •
that the ear can barely detect. Because of this vast range, any attempt to represent the
acoustic intensity of a particular sound on a linear scale becomes unwieldy. Because of
this, a logarithmic ratio known as the decibel (dB) is commonly employed. A sound level
of zero "0" dB is scaled -such that it is defined as the threshold of human hearing and
would be barely audible to a human of normal hearing under extremely quiet listening
• conditions and would correspond to a sound pressure level equal to the refeence level.
Most of the, sounds we hear in the environment do not consist of a single
frequency, but rather a broad band of frequencies differing in sound level. The
-.. - intensities of each frequency add to generate the sound we hear. The method +
commonly used to quantify environmental, sounds consists of determining alLof the
- - frequencies of a sound according to a- weighting system that reflects the nonlinear --
response characteristics of the human ear. This is called "A" weighting, and the decibel -
level measured is called the A-weighted sound level (or dBA). In practice, the level of a
noise source is conveniently measured using a sound level meter that includes a filter
corresponding to the dBA curve. • -
Although the A-weighted sound level ma/adequately indicate the level of
environmental noise at any instant in time, community noise levels vary, continuously.
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Ms. Sherri Howard - - -
Cannon Road West Frojet Initial Noise Study
ISE Report #99-007
-March 16-1999 -
Page '
-
-•'
Ms. Sherri Howard
Cannon Road West Project Initial Noise Study
ISE Report #99-007
March 16, 1999
Page
Environmental noise includes a conglomeration of sounds from distant sources that
create a relatively steady background noise in which no particular source is identifiable.
For this type of noise, a single descriptor called the Leq (or equivalent sound level) is
used. Leq is the energy-mean A-weighted sound level during a measured time interval.
It is the 'equivalent' constant sound level that would have to be produced by a given
source to equal the fluctuating level measured.
To describe time-varying character of environmental noise, the statistical noise
descriptors LIO, L50, and L90 are commonly used. They are the noise levels equaled
or exceeded during 10 percent, 50 percent, and 90 percent of a stated time. Sound
levels associated with the LIO typically describe transient or short-term events, while
levels associated with the L90 describe the steady state (or most prevalent) noise
conditions. In addition, it is often desirable to know the acoustic range of the noise
source being measured. This is accomplished through the maximum and minimum
measured sound level (Lmax and Lmin) indicators. The Lmin value obtained for a
particular monitoring location is often called the acoustic floor for that location.
Applicable Significance Criteria
Wildlife Habitat Regulations
Construction and operational noise generated by this project is regulated by the
United States Fish and Wildlife Service (U.S.F.W.S.) and the California Department of
Fish and Game for its effect on federally endangered least Bell's vireo (Vireo be/Ill
pusillus) and the southwestern willow flycatcher (Empidonax traillll extnmus) and the
federally threatened California gnatcatcher (Polioptila california).
Resource agencies have theorized that elevated noise levels can potentially
mask songs of the least Bell's vireo which are used to attract mates and defend
territories. The San Diego Association of Governments (SANDAG) in a 1990 study
entitled "Comprehensive Species Management Plan for the least Bell's vireo"
theoretically estimated that {traffic} noise levels above 60 dBA Leq in vireo breeding
areas may sufficiently mask the vireo's song and potentially reduce the reproductive
success of this species during their breeding season that occurs from March 1 to
September 1. Since sustained noise exposure (indicated by the L90 metric) produces
greater masking effects than intermittent peak levels, this report will analyze both
effects. The SANDAG report conclusions were unclear as to the specific time interval of
the measurement, but it is typically taken as one hour. Although research is on going
regarding similar noise impacts to the southwestern willow flycatcher and California
gnatcatcher, in the absence of species-specific data, these same study results are
applied by the Service to this bird species as well.
Ms. Shem Howard
Cannon Road West Project Initial Noise Study
ISE Report #99-007
March 16, 1999
Page 4
Analysis Methodology
Existing Conditions Field Survey
Three Larson Davis Model 700 ANSI Type 2 integrating sound level meters
were used as the data collection devices. The meters were positioned at the locations
shown below in Figure 2 and the accompanying matrix.
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L 12 I
Agua
\'i ,' \.1-' t• .:• \S' %e4 I
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rJ
,27
witeo ell I Tank
i4i ,i> 'i: / c;.- • 0
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vow
Figure 2: Project Area Topography (USGS 7.5 San Luis Rey Quadrangle 1:12000)
Monitor Sta. GPS Lat GPS Lon Description
ML #1 330 08.969 N 1170 17.871 W Eastern end of alignment (ECR bridge area)
ML #2 330 08.806 N 1170 18.066 W Central point of alignment near Sta. 110+00
ML #3 330 08.282 N 1170 18.471 W Macarlo Canyon bridge crossing
ECR = El Camino Real Rd.
EPE = Estimated Position Error = 49'
Ms. Sherri Howard
Cannon Road West Project Initial Noise Study' -
ISE Report #99-007
March 16, 1999
Page 5 •
The meters were mounted on tripods roughly 5 feet above the ground and were
calibrated before and after each field deployment. Each station was programmed to - -
record and log the following noise metrics each hour: Leq-h, Lmax, Lmin, LIO, L50, and
L90. The period of deployment was approximately 48 hours (between 2/17/99 to
2/19/99)
Findings
Field Monitoring Results .
Testing conditions during the monitoring period were dear .with an average
barometric pressure reading of 29.85 in-Hg, an average southwesterly wind speed of I to 6
- miles per hour (MPH), and an approximate daytime mean temperature of 70 degrees
Fahrenheit / nighttime 40 degrees Fahrenheit. The results of the 48-hour: sound level
monitoring are shown below in Figures 3a, -b, and -c. The values for the energy equivalent .
sound level (Leq) and the maximum and minimum measured sound levels (Lmax and Lmin)
are given for each monitoring location.
• • -. - : - • -
A summary of the 48-hour average levels is given in Table 1. The average sound - -
level exceeded as a function of the 48-hour monitoring period is given in Figure 4.
80
10 70
60
50 CL 40
30
--4— Leq.
—0--- Lmax
—fr— Lmin
- .c .--
:t• tx• <'y• -• I, , /, - -- •
Ms. Shem Howard
cannOn Road West Project Initial Noise Study,
tS ISE Report #99-007 - -
March 16, 1999
- Page
A A # 11 U
90
70
Cl)
• 30
—•— Leq
—O-- Lmax
—fr— Lmin
.
•ç:sil c
<i,. bi• <V r9' •
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Figure 3b: Ambient Noise Levels (Central point of alignment near Sta. 110+00— ML #2) •
Ms Shern Howard I
Cannon Road West Project Initial Noise Study - -
ISE Report #99-007
March 16, 1999
- Page 7.. - -
Table 1: 48-Hour Average Ambient Sound Levels -
48-Hour Average Noise Level Descriptors in-dBA,
Site Leq Lmax' Lmin LIO L50 L90
MLI 55.7 .66.6 46.5 58.8
-
- .54.2 50.3
-
ML 2 - 54.7 67.3 42.7 - 48.8 48.8 .- 45.9
ML 3 55.8 66.5 49.8 57.1 528 50.8
Monitonna Locations
+ ML 1 Eastern end of alignment (ECR bridge' crossing)
+ ML 2: Central point of alignment near Sta. 110+00.
+ ML 3:Macario Canyon bridge croSsing.- r. . .
Measurements performed by ISE between 2/17/99 to 2/19/99 -
- -
Ms. Sherri Howard
Cannon Road West Project Initial Noise Study
ISE Report #99-007
March 16, 1999
Page 8
Measurements collected at monitoring locations ML I through ML 3 reflect
typical sound levels associated with the community setting observed and the
topography of the surrounding terrain. The following noise sources were noted during
the monitoring period:
+ ML #1: Minimal construction activity. Some onsite truck movement. Principal
noise source was traffic activity along El Camino Real.
: ML #2: Light surface grading activities away from habitat areas. Principal
noise sources was construction activities from adjacent (non-project related)
equipment to immediate south.
. ML #3: Daytime pile driving activities responsible for impulsive noise peaks.
Background sound due to distant traffic noise and aircraft overflights from
McClellan-Palomar Airport, which is approximately 1.6 miles distant.
Based upon the findings, the 60 dBA Leq threshold is currently exceeded
approximately 15% of the time at ML'S #2 and 3 and 20% of the time at ML #1. This
exceedance is directly attributable to a) traffic activity along El Camino Real at the
eastern end of the alignment, b) non-project related construction activities adjacent to
the central portion of the project alignment, and c) aircraft activity near the western end
of the alignment. It should be noted that pile-driving activities was a significant
contributor to daytime noise levels at ML #3 (western alignment end).
It was observed that over 90 percent of the time the onsite sound levels ranged
between approximately 45 to 50 dBA enabling vireo communication within the habitat
boundaries. This is contrasted against the 48-hour energy average levels (Leq's) which
were consistent at approximately 55 dBA for all sites examined. -Again, the difference
between these two levels (Leq and L90) is directly attributable to the intermittent nature
of automobile and aircraft traffic and other sources from afar.
Finally, the acoustic floor for the site, as seen by the Lmin indicator I was
moderate (ranging between approximately 42 and 49 dBA for all locations monitored)
and reflects the community noise environment of the project site.
Anticipated Construction Noise Levels
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-
Construction at the project site is slated to occur between the hours of 7 am.
and 3 p.m. Monday through Saturday. Typical construction noise levels generated by
operational equipment at the project site is given below in Table 2. The equipment type,
equipment source level range (from quiet to poorly maintained), the maximum expected
number of equipment to be utilized, and the worst-case cumulative effect (i.e., all
equipment on at once and in one stationary location) are provided. The levels shown
are consistent with observed construction equipment utilized onsite. - -
Ms. Sherri Howard - -
Cannon Road West Project Initial Noise-Study -
V ISE Report #99-007 -
V
March 16, 1999 V
Page 9 1
TABLE 2 Anticipated Construction Activities and Typical Noise Levels
Construction Phase / Source Level @ 50 Max. Number Cumulative Effect in
Equipment Type Feet (dBA) Expected dBA
Grading
V
V
t
Earth Mover V 80-92
V
VV 5 V 86-98 V
-
V Bulldozer 75-95 - 2 V 78-98 V
V
V V - Compactor . 72-75 i V 72-75 . V•
V
V Water Truck 82-95 1 V
- 82-95 V
V Dump Truck 82-95 20- * V
V 95-108 V
-
Bridge Construction (2 Bridges) V
V
V V
V
Crane . - 75-88
-
2 78-91 V V
- V• V
V Pile Driver 94-105 V V 94-105
V Loader V 72-74 72-74 V V
Bulldozer 75-95 V
V
V
•
V
• - V 7595
Concrete Pumper 82-84 1 1.82-84
Haul Trucks . 82-95 •
V 88-101
V
Road Construction 71 1 -
V
V Bulldozer V V 7595 j V
V 7595
VV
V
V Blade Scraper 80-92 .
,V
V 80-92 V V
- Paving Equipment 86-88 1 86-88 -
V
- Compactor V - 72-75 V 3 V - - 76-79 -
Water Truck V 82-95 1 V V 82-95 V V
V
V. V
•V Haul Trucks 82-95 V 6 - 89-102 V
Source: EPA PB 206717: Environmental Protection Agency, 12/31/71, "Noise from Construction
V
V
Equipment and Operations" V
V
-, - •
V
Recommendations
-- V. V - ._ -
Ambient noise levels at the project site were found to average approximately 5 V
V
dBA below the established U.S.F.W.S. impact threshold level Vfor mixed construction
V
operations occurring within the project area. Ambient noise levels currently exceeded
V V
the 60 dBA Leq level approximately 15% of any given time interval. These V
exceedances were found to be directly attributable to traffic activity_.. adjacent- to the
project site, aircraft activity, and adjacent non-project related construction activities
• V
Ms. Sherri Howard
Cannon Road West Project Initial Noise Study
ISE Report #99-007
March 16, 1999
Page 10
Anticipated construction activities at the project site have the potential to create
adverse noise conditions (especially if performed close to the habitat boundary).
Properly mitigated, they can be performed during the vireo-breeding season (i.e., March
1 to September 1) with no significant impacts. Therefore, the following mitigation
measures are recommended:
Grading or other operations close to the habitat boundary should utilize
equipment with shielded exhaust stacks (i.e., modified exhaust stacks that point
away from the habitat area). A plywood shielding enclosure readily constructed
on-site would suffice to this end.
If Item #1 is not implementable (as would be the case for non-standard
equipment) then a temporary plywood noise barrier should be constructed near
the working area. The preferable design would be to mitigate close to the
source for stationary equipment, and close to the habitat for mobile equipment.
Idling of equipment near habitat should be kept to a minimum.
Construction phasing (i.e. operational placement and duty cycle) should be
done to minimize excessive equipment usage in any given area.
Should you have any questions regarding the above conclusion, please do not
hesitate to contact me at (619) 640-9379.
Sincerely,
ivrs
Rick Tavares 1I( No. 067 5
Project Principal I*L Exres . 1*1
Investigative Science and Engineering
Cc: Doug Gettinger, Ogden Environmental
Glen Laube, ISE