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1 vv, z, B1-\T11v10J.\J{TrrE1{ & 1-\~Boc1i~TE33111c. Efl.VIRONMENTAL ENGINEERS AND CONSULTANTS P.O. BOX FRANKLIN, TN MURFREESBORO RD., SUITE 310 FRANKLIN, TN FAX W. Z. BAUMGARTN ER, JR., P.E., DEE, CHMM. REM MICHA ELE TANT, P.E. J. CLAIBORNE THORNTON, Ill. P.E. Supervisor Compliance Determination Unit Air Quality Division Minnesota Pollution Control Agenct 520 Lafayette Rd. North St. Paul, NMN November 6, 2009 JASON K. Wl"lNJNGHAM. P.E. GRAHAM P McREDMOND, P.E. DANIEL PREBONICK WC. BARRON BRANDON WALSH Subject: Noise Monitoring Plan for American Iron & Supply Company (Northern Metals), 2800 Pacific Street North, Minneapolis, MN (for Permit Number ) As required by the Minnesota Pollution Control Agency (MPCA) Permit Number we are submitting this Noise Monitoring Plan for the subject facility, in accordance with Minn. R , Measurement Methodology. The measurements will be made to conformifthe measured levels comply with the sound level limits in Minn. R , Noise Standards. Questions on technical noise measurement issues were discussed with Ms. Anne Claflin, Noise Specialist at the MPCA, as part of the preparation of this Plan. Our Associate firm, Bowlby & Associates Inc., has had noise studies as its focus since I 991. Dr. William Bowlby Ph.D., P. E. is editor of Sound Procedures.for Measuring Highway Noise: Final Report, which is incorporated by reference into Minn. R , Incorporation by Reference. The actual measurements will be done by Mr. Clay Patton, who has 18 years experience under Dr. Bolwbty s direction and supervision. L Area Description Winel-Om Park - The map to the right shows the general location of the facility (labeled "A"). It is bordered on the east by the Mississippi River, on the., north by 31 Ave. N., on the west by N. Pacific Street, lh and on the south by 28 Ave. N. 16IhAveNE Co O.m

2 Across the river, as shown in the aerial photo below, is a largely residential area, which is mostly Class l per Minn. R , Subpart 2 (Noise Area Classifications). The closest residences are nd nl on N. Marshall Street (County Road 23) between 22 and 23 Avenues North, and they back up to the river. There are eight detached residences, an apartment building (with a ''garden" level and two fully above-ground upper levels), and two small commercial buildings. The apartment building has no apparent outdoor use areas, with a parking lot separating the building from the river bank. Bordering this residential area on the south is Gluek Riverside Park, and, on the north, another small park area. The facility's river frontage is approximately 1,600 feet long. The residential area's river frontage is approximately 880 feet long and is roughly centered on the center of the facility's frontage.

3 The land use to the north, west and east ofth~ facility appear to be commercial or industrial, which are Class 3 per Minn. R , Subpart 2. We have reviewed the aerial photos, shown below, and confirmed with the facility's management that there are no Class I land uses on the west side of the river near the facility.

4 II. Noise Monitoring Plan Measurement date and time: The measurements will performed on December 8, 2009, weather permitting. Back-up dates will be December 9 and 10 in case of precipitation, high winds, or winds from the east, northeast or southeast (which would reduce the levels compared to those measured during winds from the other directions). The facility operates between 7 a.m. and 6 p.m. The measurement will be made during the daytime hours. Because of concerns about background noise from the neighboring Class 3 properties, the facility owner has agreed to shut down operations during the lunch period. This is to allow us to measure "source" noise for the one-hour period before lunch, to measure background for minutes during lunch and then measure "source'' noise for a one-hour period after lunch. The measurement descriptors will be the L l 0 ( 1 hour) and the L50 ( 1 hour). III. Minn. R Measurement Methodology Subpart 1. Measurement location. Measurement of sound must be made at or within the applicable NAC at the point C)f lmman activity which is nearest to the noise source. All measurements shall be made outdoors. The measurement will be made on the north end ofgluek Park immediately south of the residential properties on N. Marshall Street. This location is directly across the river from the subject facility and almost in line with the center of the facility's river frontage. This site is preferred over one of the residential backyard, because it will not require permission to access private property and will be less likely for local noise sources such as dogs, or mechanical air handling systems, to influence the measurements

5 Should there be a problem with this location on the day of measurements, two back-up sites will be considered. The first is the small park area to the immediate north of the residential area, while the second is the rear parking lot of the apartment building. Advance permission will be sought from the apartment owner. One concern about the apartment site would be the movement of vehicles into and out of the lot, which would cause noise interference, requiring the measurements to be paused and then resumed. No measurements are planned at the Class 3 land uses adjacent to the facility. These commercial and industrial land uses are not noise-sensitive, and are likely to be generating their own noise, which would make it impossible to get valid measurements of the subject facility's levels on their properties. Ill. Subpart 2. Equipment specifications. All sound level measuring devices must meet Type 0, LIL or S specifications under American National Standards Institute Sl We will use one of the following sound level measuring devices, all of which meet ANSI S Type II or better: Norsonic 121 Rion RL-32 or Larson Davis LxT. We will support the microphone on a tripod and place a windscreen on top of the microphone during the measurements. IV. Subpart 3. Calibration. All sound level measuring devices must, at a minimum, be externally field calibrated before and after monitoring using a calibration device of known frequency and sound pressure level. We will calibrate the sound level measuring device in the field before and after each measurement using a calibrator recommended by the measuring device manufacturer. If calibration shifts by more than 0.5 db, we will repeat the measurement. V. Subpart 4. Measurement procedures. A. Measurements must be made at least three feet off the ground or surface and away from natural or artificial stroctures which would prevent an accurate measurement. Microphone height will be between 4 and 5 feet above the ground, and will be at least 10 feet away.

6 B. Measurements must be made using the A-weighting and.fast response characteristics of the sound measuring device as spec(fied in American National Standards Institute SJ We will measure using A-weighting and fast response. C. Measurements must not be made in sustained winds or in precipitation i1- hich results in a d(fference of less than ten decibels between the background noise level and the noise source being measured. We will monitor weather conditions prior to the measurement trip and during the measurements. We will measure wind speed and direction with a handheld wind speed indicator, and will obtain temperature and humidity data from local weather services. We will not measure if winds equal or exceed 11 mph, if winds are from the east, northeast or southeast, or if there is precipitation. We will measure background noise while the facility is shut down for lunch. If there is a difference of less than ten decibels between the background noise level and the 'total'' sound level, (background plus facility), we will adjust the total level using the procedure in MPCA 's "A Guide to Noise Control in Minnesota: Acoustical Properties, Measurement, Analysis and Regulation. " D. Measurements must be made using a microphone which is protected.from ambient conditions which would prevent an accurate measurement. As noted above, we will use a windscreen on the microphone, will not measure during high winds or precipitation, and will measure the background sound levels during the facility's lunch period. VL Subpart 5. Data documentation. A summary sheet.for all sound level measurements shall be completed and signed by the person making the measurements. At a minimum, the summary sheet shall include: A. date; B. time; C. location; D. noise source; E. wind speed and direction; F. temperature; G. humidity; H. make, model, and serial number of measuring equipment; I..field calibration results; J. monitored lei els; and

7 K. site sketch indicating noise source, measurement location. directions, distances, and obstructions. We will use the data sheet in the MPCA Guide, or equivalent, and will record the needed information. We will then present the results in a letter report. If you have any questions, please do not hesitate to call on me. Sincerely, ASSOCIATES, INC.