The URL can be used to link to this page

Home My WebLink About3184; CANNON ROAD WEST; FALSEWORK REMOVAL COMPLIANCE STATEMENT; 1999-07-01FILE RECEIVED 9 Investigative Science and Engineering J U L 13 1999 3511 Camino Del Rio South, Suite 302 Phone/Fax: 619-640-9379 San Diego, CA 92108-4003 ONG DEPARTMENT July 1, 1999 Mr. Greg Ponce Shea Homes 10721 Treena Street, Suite 200 San Diego, CA 92131 Re: Cannon Road I El Camino Real Bridge Falsework Removal Compliance Statement (ISE Report #99-028b) Dear Mr. Ponce: At the request of Shea Homes, Investigative Science and Engineering (ISE) has performed an acoustical verification study for falsework removal operations adjacent to riparian habitat along the proposed Cannon Road I El Camino Real bridge crossing located in Carlsbad, California. The verificatiOn survey was performed on -July 1, 1999. The results of that survey are presented below. Introduction and Definitions The Cannon Road West Project consists of two bridge crossings, which 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. 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//li pusilus). For the purposes of compliance, a 60 cIBA Leq noise threshold standard has been adopted during their breeding season whichoccurs from March 1 to September 1. The quantity Leq (or equivalent sound level) is the energy-mean A-weighted sound level during a measured time interval (typically one-hour). 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 L1 1 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 Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028b July 1, 1999 Page 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. IM Proposed Action The proposed action calls for the removal of the falsework (i.e., temporary support structures) holding up the El Camino Real Bridge. This falsework was necessary to provide structural rigidity to the bridge during the concrete pouring and curing phases of the project. The expected duration of this ãctivityis three days. Site Survey Results The proposed habitat in question consists of approximately 0.25 acres residing between the El Camino Real Bridge site and El Camino Real {road}. A Larson Davis Model 700 ANSI Type 2 integrating sound level meter was used to collect ambient construction noise data adjacent to the habitat frontage (refer to Figures 1 through 3, ML 1). The meter was positioned as shown. The hourly-average measured results are shown below in Table 1. Table 1: Measured Construction Levels -, Falsework Removal Operations (ML 1) I 1 -Hour Noise Level Descriptors in dBA Time Leq Lmax Lmin 8:30 59.0 78.5 44.5 62.0 56.0 52.0 9:30 59.5 78.5 47.5 63.0 56.5 51.5 10:30 57.5 75.5 44.5 60.0 55.5 52.5 Based upon the findings, the expected approximate 14 dBA of acoustical attenuation due to the presence of the berm was indicated. None of the noise levels measured due to construction activities was found to be impactive to the habitat. The predominant noise source indicated was from adjacent El Camino Real (as can be seen from the higher peak-hour traffic noise levels during the 8:30 and 9:30 hours). Conclusions I Recommendations No significant impacts due to construction noise associated with falsework removal were found. No additional recommendations for, mitigation measures were indicated. S . . .••• •'••,•- • .•••J•,' j •-;c'c. y •' - Falsework Area p 1 1)I'1ifç; I I 6 V - - 'L.L- •' -' VI cS4 ECEIVED &gative Science and Engineering. J L 02 1999 3511 Camino Del Rio South, Suite 302 Phone/Fax: 619-640-9379 / 619-640-Qj'63INEERlN G San Diego, CA 92108-4003 www.iseadvantage.Q5pARTMENT June 29, 1999 Mr. Greg Ponce Shea Homes 10721 Treena Street, Suite 200 San Diego, CA 92131 C(DFV Re: Cannon Road I El Camino Real Bridge Falsework Removal Noise Issues (ISE Report #99-028a) Dear Mr. Ponce: At the request of Shea Homes, Investigative Science and Engineering (ISE) has examined potential impacts attributable to falsework removal operations adjacent to the riparian habitat along the proposed Cannon Road I El Camino Real bridge crossing located in Carlsbad, California. A field survey of the site was performed on June 29, 1999. The results of that survey are presented below. Introduction and Definitions The Cannon Road West Project consists of two bridge crossings, which 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. Construction and operationalnoise 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). For the purposes of compliance, a 60 dBA Leq noise threshold standard has been adopted during their breeding season which occurs from March 1 to September 1. The quantity Leq (or equivalent sound level) is the energy-mean A-weighted sound level during a measured time interval (typically one-hour). 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 L10, 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 Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028a June 29, 1999 Page S 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. EN Proposed Action The proposed action calls for the removal of the falsework (i.e., temporary support structures) holding up the El Camino Real Bridge. This falsework was necessary to provide structural rigidity, to the bridge during the concrete pouring and curing phases of the project. Removal of the falsework entails literally knocking down the temporary support structures and pulling them out from underneath the bridge using a single CAT dozer (model D8 or D9L). Sound emissions from this type of equipment have already been cataloged by ISE as part of our mitigation monitoring effort for the City of Carlsbad. Typical noise levels were measured as 72-dBA at 50 feet from the exhaust stack. Site Survey Results The proposed habitat in question consists of approximately 0.25 acres residing between the El Camino Real Bridge site and El Camino Real {road}. A Larson Davis Model 700 ANSI Type 2 integrating .sound level meter was used to collect ambient peak-hour traffic noise data adjacent to the habitat .frontage (refer to Figure 1, ML 1). The meter was positioned as shown below in Figure 1. The measured results are shown below in Table 1. Table 1: Measured Construction Levels - CannónRoad Bridge Monitoring (ML 1) 1:HbUr:Noise,Level Descriptors In dBA .. Site Leq Lrnax Lmin LIO L50 L90 9:30 a.m. 68.9 88.5 52.0 72.0 66.5 58.5 As can be seen from the monitoring results, the ambient sound level adjacent to the habitat is currently in excess of the 60-dBA Leq-h threshold. Maximum levels were found to exceed 88 dBA and were due to non-project related traffic activity along El Camino Real. The difference between the LIO and L90 indicators (13.5 dBA) clearly indicates the intermittence of the noise levels (which is a common occurrence with traffic related noise). Topographically, the falsework construction area lies within the depression formed by the Agua Hedionda Creek. Directly adjacent to this area is an artificial berm that is currently diverting the creek for construction purposes (refer to Figures 2 and 3). Based upon the size Of the berm and the relative placement of the falsework construction and habitat area, the. Fresnel Diffraction Method predicts a maximum attenuation (insertion loss) of 14 dBA due to the presence of the berm. Since the lei Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028a June 29, 1999 Page 3 proposed vehicle emission levels are approximately 72 dBA, noise produced by the falsework construction should not produce a significant impact on the habitat area, and in fact should be indiscernible from existing traffic noise during most phases of the operation. Conclusions I Recommendations Construction noise associated with falsework removal is not expected to produce a significant impact within the adjacent habitat area between the project bridge and El Camino Real due to the presence of an artificial berm which is currently diverting the creek for construction purposes,. A maximum attenuation level of 14 dBA is predicted between the falsework construction site and the habitat area. To verify the above findings, ISE recommends monitoring within the habitat area during falsework removal. Any variances in the above predicted noise levels would be corrected on an as-needed basis. No additional mitigation measures are recommended for this phase of construction. Should you have any questions regarding the above conclusion, please do not hesitate to contact me at (619) 640-9379. MENTk TAV Rick Tavares, REA; INCE I No. 0677 Project Principal' Investigative Science and Engineering OF CALIV: Cc: Leo Todd, Shea Homes Doug Géttinger, Ogden Environmental Shem Howard, City of Carlsbad Glen Laube, ISE Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results lSE Report #99-028a June 29, 1999 Page 4 Figure 1: Noise Monitoring Location - El Camino Real (ML 1) Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028a June 29, 1999 Page 5 Figure 2: El Camino Real Bridge Crossing - Diversion Berm/Falsework Area Mr. Greg Ponce Cannon Road Bridge Construction Monitoring Results ISE Report #99-028a June 29, 1999 Page 6 * I 1 I1 Tf- - ':'- •-;- ____ lo 5s, '- -- *i_ . . A- '.;' -•'-.•.r• . • . - -.-. .—..- - .. -.----.-. .--.. -.5 .. .. - . - .. . - . .•.rq_u_ - - - — ...-,_;_4__,_. - __ .l.,____..__._J_.__s___ --.- -'I.-- - •-12 .-- _-f'--V. -i______ - ' '-'.::.- t•l-_. r':i .-•'; ? - r-' - - -'. : - - -. - - -w--- '- - •.- _ - — ç j Figure 3: Diversion Berm Blocking Habitat Area I 1