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1、SR XXXProject Name UNDERWATER NOISE MONITORING PLAN*TEMPLATE*Replace underlined blue italic text with project information.Blue italic text is guidance.Plain, black text is template language. All blue italic text should be replaced or omitted for final production.Prepared by:Washington State Departme
2、nt of TransportationOffice of Air Quality and Noise15700 Dayton Avenue North, P.O. Box 330310Seattle, WA 98133-9710DateINTRODUCTION (This section will be project specific)The agency name proposes to project description. See vicinity map (Figure 1). Figure 1. Vicinity map of name project.PROJECT AREA
3、 (This section will be project specific)The project is located on SR XX (Figure 1).PILE INSTALLATION LOCATION (This section will be project specific)Figure 2 indicates the location of the provide location of the structure(s) in need of pile driving. There will be a total of XX piles driven as part o
4、f the name structure(s).Figure 2. Location of name structure(s) where pile driving activity will take place.PILE INSTALLATION Provide pile installation information. For example:Hydroacoustic monitoring will be conducted for X piles struck with an impact hammer. Piles were chosen to be monitored are
5、driven in water depths that are representative of mid-channel or typical water depths at the project location where piles will be driven. Provide additional information here on the considerations taken in choosing a representative number of piles such as, bathymetry, total number of piles to be driv
6、en, substrate type, depth of water, and distance from shore. A minimum of 5 piles should be monitored. Projects driving a large number of piles, driving multiple piles diameters in differing substrates, driving different types of piles, or driving piles in widely differing depths, may warrant additi
7、onal monitoring to produce a representative sample. Hydroacoustic monitoring of type of pile driving will include: Measuring underwater background levels, Monitoring X piles, Testing sound attenuation system effectiveness. Include airborne noise monitoring as bullet here if necessary for other liste
8、d species (e.g.marine mammal haul out present, marbled murrelet nest present, etc.).Figure 3 indicates the location of the piles to be monitored and the approximate hydrophone locations for each pile being monitored. Hydrophones will be located 10 meters from each pile with a clear line-of-sight bet
9、ween the pile and the hydrophone. Additional distances measured concurrently are desirable if possible to estimate the site specific transmission loss. Include any additional distances or depths where hydrophones will be located.Figure 3. Location of the piles that will be monitored on the name stru
10、cture(s).Table 1 lists the name structure(s) to be installed, the water depth, and the number and size of piles that will be installed.Table 1 Depth, Number Piles to be Monitored StructureWater DepthStructural Components InstalledName structureX feet to X feetX - XX-inch diameter type of pile METHOD
11、OLOGYBackground underwater noise levels will be measured for a minimum of three full 24-hour cycles (i.e., 6 am to 6 am) in the absence of construction activities to determine background sound levels (Stockham et al., 2010). Following NMFS guidance (NMFS, 2009), analysis will be conducted using both
12、 data from the full range of frequencies recorded and using a high pass filter at 1000 Hz thus eliminating those frequencies below 1000 Hz which killer whales cannot hear. Data will be used to calculate 30-second Root Mean Square (RMS) values for each 30 seconds of the three 24-hour cycles measured.
13、 These data will be used to calculate and plot a Cumulative Distribution Function (CDF) (NMFS, 2009). Overall average background sound levels will be reported as the 50% CDF and include a spectral analysis of the frequencies (NMFS, 2009) for a minimum of an hourly cycle. As this is an evolving scien
14、ce, please coordinate with WSDOT and NMFS about current methodology for measuring and monitoring background noise levels.All piles monitored will be tested with the sound attenuation system, on and off (presence and absence) to test its effectiveness Note: There may be circumstances where the U.S. F
15、ish and Wildlife Service determines that unattenuated pile driving (striking the pile with the bubble curtain turned off) would pose a significant risk of injury to marbled murrelets. In those situations, the Service may request that unattenuated pile driving does not occur and that hydroacoustic mo
16、nitoring be conducted to determine the extent at which certain thresholds are met instead. This will need to be determined on a case by case basis for projects that may affect marbled murrelets. To account for varying resistance as the pile is driven; the sound attenuation device will be turned off
17、for 30 second periods during the beginning, the middle third, and near the end of the drive. Pile driving should resume for a minimum of two minutes after each 30 second period the attenuation device is off. For piles that require less than 5 minutes to drive, the sound attenuation system should be
18、turned off for only two 30-second periods, one near the beginning and once near the end of the drive.Table 2 details the equipment that will be used to monitor underwater sound pressure levels.Table 2.Equipment for underwater sound monitoring (hydrophone, signal amplifier, and calibrator). All have
19、current National Institute of Standards and Technology (NIST) traceable calibration. If acoustic monitoring for a WSDOT project is conducted by a contractor and not conducted directly by WSDOT, the contractor will submit a detailed description of their qualifications, which must include a minimum of
20、 an appropriate bachelors degree and 3 years experience in noise monitoring and analysis, and monitoring plan based on this template for approval by a WSDOT acoustic specialist. The approved contractors equipment list should be listed in the table.ItemSpecificationsQuantityUsageHydrophone with 200 f
21、eet of cableReceiving Sensitivity-211dB 3dB re 1V/Pa1Capture underwater sound pressures and convert to voltages that can be recorded/analyzed by other equipment.Signal Conditioning Amplifier (4-channel)Amplifier Gain- 0.1 mV/pC to 10 V/pCTransducer Sensitivity Range- 10-12 to 103 C/MU1Adjust signals
22、 from hydrophone to levels compatible with recording equipment.Calibrator (pistonphone-type)Accuracy- IEC 942 (1988) Class 11Calibration check of hydrophone in the field.Portable Dynamic Signal Analyzer (4-channel)Sampling Rate- 24K Hz or greater1Analyzes and transfers digital data to laptop hard dr
23、ive.Microphone (free field type)Range- 30 120 dBASensitivity- -29 dB 3 dB (0 dB = 1 V/Pa)1Monitoring airborne sounds from pile driving activities (if not raining).If velocity 1m/s, Flow shieldOpen cell foam cover or functional equivalent1/hydrophoneEliminate flow noise contamination.Laptop computerC
24、ompatible with digital analyzer1Record digital data on hard drive and signal analysis.Real Time and Post-analysis software-1Monitor real-time signal and post-analysis of sound signals.Monitoring equipment will be set to X Hz to X kHz with a sampling rate of X Hz. A minimum frequency range of 20 Hz t
25、o 10 KHz and a minimum sampling rate of 24,000 Hz will be used when monitoring. Sampling rates higher than 24 kHz are preferred. To facilitate further analysis of data the underwater signal will be recorded as a text file (.txt) or wave file (.wav). The hydrophone(s) will be placed at name depth in
26、water column (this is usually mid-water) depth at distance of 10 meters from each pile being monitored. Mid-water depth is typical, but if water velocity is 1 meter/second or greater, 1-3 meters off the bottom may be recommended for near field hydrophones and greater than 5 meters from the surface m
27、ay be recommended for any far field hydrophones. A weighted tape measure will be used to determine the depth of the water. The hydrophone(s) will be attached to a nylon cord or a steel chain if the current is swift enough to cause strumming of the line. The nylon cord or chain will be attached to an
28、 anchor that will keep the line the appropriate distance from each pile. The nylon cord or chain will be attached to a float or tied to a static line at the surface. The distances will be measured by a tape measure, where possible, or a range-finder. There should be a direct line of sight between th
29、e pile and the hydrophone(s) in all cases. If water velocity will be greater than 1 meter/second, then add the following text: For background measurements when the water velocity is greater than 1 meter/second, a flow shield around each hydrophone will be used to provide a barrier between the irregu
30、lar, turbulent flow and the hydrophone. Velocity will be measured concurrent to sound measurements. If velocity is greater than 1 meter/ second, a correlation between sound levels and current speed will be made to determine whether the data is valid and should be included in the analysis. The hydrop
31、hone calibration(s) will be checked at the beginning of each day of monitoring activity. Prior to the initiation of pile driving, the hydrophone will be placed at the appropriate distance and depth as described above. The inspector/contractor will inform the acoustics specialist when pile driving is
32、 about to start to ensure that the monitoring equipment is operational. Underwater sound levels will be continuously monitored during the entire duration of each pile being driven. Peak levels of each strike will be monitored in real time. Sound pressure will be measured in Pascals which are easily
33、converted to decibel (dB) units (e.g. 1000 Pascals = 180 dB). During three 30-second periods distributed throughout the drive while the pile is being driven with an impact hammer, the bubble curtain will be turned off near the beginning, middle and end of the drive. If piles are likely to be driven
34、in less than 5 minutes add the following text: For piles that require less than 5 minutes to drive, the bubble curtain will be turned off for only two 30-second periods, one near the beginning and once near the end of the drive. Prior to, and during, the pile driving activity, environmental data wil
35、l be gathered, such as wind speed and direction, air temperature, humidity, surface water temperature, water depth, wave height, weather conditions, and other factors that could contribute to influencing the underwater sound levels (e.g. aircraft, boats, etc.). Start and stop time of each pile drivi
36、ng event and the time at which the bubble curtain or functional equivalent is turned on and off will be recorded. The chief inspector will supply the acoustics specialist with a description of the substrate composition, approximate depth of significant substrate layers, hammer model and size, hammer
37、 energy settings and any changes to those settings during the piles being monitored, depth pile driven, blows per foot for the piles monitored, and total number of strikes to drive each pile that is monitored.SIGNAL PROCESSINGPost-analysis of the sound level signals will include determination of the
38、 maximum absolute value of the instantaneous pressure within each strike, Root Mean Square (RMS) value for each absolute peak pile strike, mean and standard deviation/error of the RMS for all pile strikes of each pile, rise time, number of strikes per pile and per day, number of strikes exceeding 20
39、6 dBpeak, number or percent of individual strikes exceeding 183 dB Sound Exposure Level (SEL) and 187 dB SEL, SEL of the pile strike with the absolute peak sound pressure, mean SEL, and cumulative SEL (cumulative SEL = single strike SEL + 10*log (# hammer strikes) and a frequency spectrum both with
40、and without mitigation, between a minimum of 20 and 10,000 Hz for up to eight successive strikes with similar sound levels. Calculation methodology is provided in Appendix A. When possible the single strike SEL for each hammer strike will be estimated and then these values will be accumulated for th
41、e cumulative SEL value (See Appendix A).Background sound levels will be analyzed by calculating 30-second RMS values and plotting these values on a CDF. The average background sound level will be estimated using the 50% CDF (See Appendix B). ANALYSISAnalysis of the data from the San Francisco-Oaklan
42、d Bay Bridge Pile Driving Demonstration project (PIDP) indicated that 90 percent of the acoustic energy for most pile driving impulses occurred over a 50 to 100 milliseconds period with most of the energy concentrated in the first 30 to 50 milliseconds (Illingworth and Rodkin, 2001). The RMS values
43、computed for this project will be computed over the duration between where 5% and 95% of the energy of the pulse occurs. The SEL energy plot will assist in interpretation of the single strike waveform. The single strike SEL associated with the highest absolute peak strike along with the total number
44、 of strikes per pile and per day will be used to calculate the cumulative SEL for each pile and each 24-hour periodIn addition a waveform analysis of the individual absolute peak pile strikes will be performed to determine any changes to the waveform with the name type of noise attenuation device. A
45、 comparison of the frequency content with and without noise attenuation will be conducted. Units of underwater sound pressure levels will be dB re: 1 micropascal and units of SEL will be re: 1 micropascal2sec. REPORTINGAn analysis of the change in the waveform and sound levels with and without the n
46、ame type of noise attenuation device operating will be conducted. A draft report including data collected and summarized from all monitoring locations will be submitted to the Services within 60 days of the completion of hydroacoustic monitoring. The results will be summarized in graphical form and
47、include summary statistics and time histories of impact sound values for each pile. A final report will be prepared and submitted to the Services within 30 days following receipt of comments on the draft report from the Services. The report shall include:1. Size and type of piles.2. A detailed descr
48、iption of the name type of noise attenuation device, including design specifications.3. The impact hammer energy rating used to drive the piles, make and model of the hammer.4. A description of the sound monitoring equipment.5. The distance between hydrophone(s) and pile.6. The depth of the hydrophone(s) and depth of water at hydrophone locations.7. The distance from the pile to the waters edge.8. The depth of water in which the
