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Home My WebLink About3184; CANNON ROAD WEST; BRIDGE CONSTRUCTION MONITORING RESULTS; 1999-06-02I' Investigative Science and Engineering 3511 Camino Del Rio South, Suite 302. Phone/Fax: 619-640-9379 /619-640-0763 San Diego, CA 92108-4003 www.ise-advantage.com June 2, 1999 Mr. Greg Ponce Shea Homes 10721 Treena Street, Suite 200 San Diego, CA 92131 Re: Cannon Road I El Camino Real Bridge Construction Monitoring Results (ISE Report #99-028) - Dear Mr. Ponce: At the request of Shea Homes, Investigative Science and Engineering (ISE) has examined potential impacts attributable to concrete pumping operations adjacent to the riparian habitat along the proposed Cannon Road / El Camino Real bridge crossing located in Carlsbad, California. A field survey of the site was performed on May 27, 1999. 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 El Camino Real Bridge crossing area is the subject of this report. 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, pie-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 /4' '• -'4 4- :. A ) -, -(lv gi -4; nhAli '-': M6, - Y SIR 4-4c- Figure 1 Project Alignment Area Map (Thomas Guide Pages 1126, 1127, and 1107) 4- Acoustical Definitions 4-I Airborne sound is a rapid fluctuation of air pressure above and 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 acoustic energy 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 k 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 reference 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 all of 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 may adequately indicate the level of environmental noise at any instant in time, community noise levels vary continuously 4. Environmental noise includes a conglomeration of sounds from distant sources that - Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028 June 2, 1999 Page 3 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 dunng 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//il pusillus) and the southwestern willow flycatcher (Empidonax trailill extrimus) 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. ' . Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028 June 2, 1999 Page Analysis Methodology Existing Conditions Field Survey A Larson Davis Model 700 ANSI Type 2 integrating sound level meter (ML #1) and a Larson Davis 800B ANSI Type 1 one-third-octave band analyzer were used as the data collection devices. The meters were positioned at the locations shown below in Figure 2 and the accompanying matrix. ' / '..J .' .1 S. II :. .: -. . . •. .. \ . Y'•. S S. N 5S ..• S Ar -__ . N '' ;).. ! •' . V r - . 7$intorosa .-.:..:./I(' .çjt SS\\ - Construction Monitoring Location ML 1 ' Country 30 , /49Uo. 31 I/Fly Ne/MN 0 1/2 1 MILE Iit,o 1000 0 1000 2000 3000 4000 FEET / .112 I Figure 2: Project Area Topography (USGS 7.5 San Luis Rey Quadrangle 1:12000) Monitor Sta. Eng, Sta. No. : GP Lát •• • GPS Lon Description ML #1 n/a 330 08.952 N 1170 17.895 W ECR bridge crossing ECR = El Camino Real Rd. EPE = Estimated Position Error = 49' Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028 June 2, 1999 Page Monitoring Location #1 was placed within the habitat area directly adjacent to the subject construction area. The meter was mounted on a tripod roughly 5 feet above the ground and was calibrated before and after the field deployment. The Larson Davis 800B was hand-held and utilized to monitor each piece of equipment observed at this location as well as the measured attenuation of the supplemental noise mitigation. Monitoring location #1 was programmed to record and log the following noise metrics each hour: Leq-h, Lmax, Lmin, LIO, L50, and.L90. Findings Field Monitoring Results During the monitoring period, construction activities were primarily affiliated with the pouring of cement to create the bridge deck of the Cannon Road I El Camino Real bridge. Equipment observed at this location consisted of multiple cement haulers, which would deposit their load into a cement "hopper" located adjacent to monitoring location #1. The cement haulers worked in a continuos cycle, entering and exiting the project site via El Camino Real. Additional equipment being utilized during this monitoring period included a single CAT dozer (model D9R), a Bidwell cement "smoother", and a model 9038 turbo forklift. Testing conditions during the monitoring intervals were clear with an average barometric pressure reading of 30.00 in-Hg, an average westerly wind speed of 0 to 5 miles per hour (MPH), and an approximate mean temperature of 70 degrees Fahrenheit. The results of the sound level monitoring are shown below in Table 1. The values for the energy equivalent sound level (Leq), the maximum and minimum measured sound levels (Lmax and Lmin), and the statistical indicators L10, L50, and L90, are given for monitoring location #1. Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results lSE Report #99-028 June 2, 1999 Page 6 Table 1: Measured Construction Levels - Cannon Road Bridge Monitoring (ML 1) I 1 -Hour Noise Level Descriptors in dBA Site Leq Lmax Lmun LIO L50 L90 6:30 a.m. 63.0 72.0 49.5 66.5 61.0 55.0 7:30 a.m. 65.0 71.0• 54.5 67.5 64.5 59.0 8:30 a.m. 65.0 76.5 51.0 67.5 64.5 59.5 9:30 p.m. 64.0 74.0 52.5 67.0 64.0 57.0 10:30 p.m. 62.5 59.0 51.5 66.0 62.5 55.5 11:30 p.m. 63.5 70.5 52.0 66.0 63.5 57.0 12:30 p.m. 64.5 74.0 52.5 66.5 64.0 59.0 1:30 p.m. 62.5 69.5 52.5 65.5 62.0 57.0 Measurements collected at monitoring location ML I reflect typical sound levels associated with the community setting observed and the topography of the surrounding terrain. Monitoring location #1 showed a slight exceedance of the 60-dBA Leq threshold throughout the duration of the monitoring period due to the elevation of the concrete pump extension arm above the habitat canopy. The highest noise levels occurred during the 7:30 to 8:30 monitoring hour and were directly attributable to the increased peak-hour traffic volume along adjacent El Camino Real. Sound levels of operational equipment measured utilizing the LID 800B analyzer indicated levels approaching 85 dBA adjacent to the concrete pumper and loading area. Levels near the active pour (i.e., adjacent to the Bidwell machine and ejection nozzle) were slightly lower and ranged between 70 to 75 dBA. In anticipation of these exceedances, additional acoustical mitigation and onsite monitoring was implemented by Shea Homes in order to reduce impacts as much as possible (see Figures 3 and 4). A secondary plywood noise wall directly adjacent to the concrete pump housing and diesel power plant was used. This mitigation, combined with the steep slope adjacent to the habitat, reduced the ambient level just outside the noise wall to approximately 65 to 68 dBA. A further reduction due to the primary noise wall yielded an additional 3 to 5 dBA within the habitat itself. Consequently, the background noise level (L90) within the habitat area did not exceed 59.5 dBA thus enabling vireo communication even within the affected areas. Conclusions Additional mitigation measures proposed by ISE and implemented by Shea Homes was found to adequately minimize construction noise impacts associated with the May 27, 1999 bridge deck pour. No residual impacts were noted.. Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028 June 2, 1999 Page Should you have any questions regarding the above conclusion, please do not hesitate to contact me at (619) 640-9379. Sincerely, , Rick Tavares, REA, INCE Project Principal No Investigative Science and Engineering Cc: Leo Todd, Shea Homes Doug Gettinger, Ogden Environmental Sherri Howard, City of Carlsbad Glen Laube, ISE Figure 3: Additional Mitigation Effort for Concrete Pumping Operations (El Camino Real Bridge Crossing) dW Tii -T - .•;-_. If: - - t r