Children's Center Noise Monitoring Monday, October 08, 2012

Transcription

1 Monday, October 08, 2012

2 Tuesday, October 09, 2012

3 Wednesday, October 10, 2012

4 Thursday, October 11, 2012

5 Friday, October 12, 2012

6 Monday, October 15, 2012

7 Tuesday, October 16, 2012

8 Wednesday, October 17, 2012

9 Thursday, October 18, 2012

10 Friday, October 19, 2012

11 P. (206) F. (206) Etruria St, Suite Seattle, WA Memo To: Troy Stahlecker, University of Washington, Project Manager From: Joel Esselstrom, SSA Acoustics, Senior Technician Date: October 25, 2012 Re: UW Lander Hall Construction Noise Monitoring: Week 4-5 SSA Acoustics, LLP Dear Troy, This memo addresses the noise impact from the UW Lander Hall project construction activity to the UW Children s Center. This memo summarizes our current observations and data collected for the two week period between October 8, 2012 and October 19, The results include two long term measurements: one taken at the edge of the play area under the cover of the overhanging roof in the middle of the play area, and the other on the inside of the Children s Center in the commons area near the exterior window to the east. The results are limited to data recorded during the Children s Center hours of operation, which are 7:00 a.m. to 6:00 p.m. The Lander Hall and Children s Center sites both fall under Major Institution (MI) zoning. This type of zoning differs to sub zonings for noise compliance purposes. Both sites are considered commercial. The noise limits below are summarized from section Please refer to the exact noise ordinance for more complete information. Seattle Noise Ordinance: Chapter III Environmental Sound Levels Exterior Sound Level Limits The limit for a commercial noise source to a commercial receiver is dba (Leq) at the property line. During a measurement interval, the Lmax may exceed the Leq by no more than 15 dba Sound Created by Construction and Maintenance Equipment The exterior sound level limits established in Section , as measured from the property line of the real property of another person or at a distance of feet from the construction noise source, whichever is greater, may be exceeded during the following times by the following: Within Commercial zones, between 7 a.m. and 7 p.m. on weekdays, limits may be exceeded by 25 dba for equipment on construction sites. Therefore, the ordinance requires that construction noise not exceed Leq dba at the Children s Center property lines, since the property line is approximately feet from the Lander Hall site, and noise level is limited at the property line or any person on the property at feet, whichever is greater. The code does not specify a different Lmax limit for construction activity. However, we assume that the Lmax limit increases with the Leq for construction activity.

12 Page 2 of 2 Since our outdoor monitor is placed adjacent to the playground and not at the north property line, we will establish an equivalent noise limit that factors in the increased noise reduction from the increased distance. We calculate that construction noise will only be 6 dba louder at the north property line of the Children s Center given the increase in proximity. Therefore, construction noise will not exceed the dba noise limit at the property line if it does not exceed 79 dba at the play area monitor location. Given that the Children s Center is simply classified as a commercial property, the noise ordinance does not factor in any additional level of sensitivity for a day care. Therefore, we recommend setting a goal of dba for construction noise at the outdoor play area in order to achieve an acceptable noise environment for children. This was also established as our goal for the previous year of noise monitoring for the UW ECC project. Weekly Site Observation: We visited the site at 2:00 a.m. on October 25, At this time, there was no audible construction activity inside or outside the Children s Center. A noise level of 54 dba was measured with a handheld sound level meter at the outside measurement location for a short duration. We also documented the interior noise level of the Children s Center during our site visit, which was dba for a short duration. At this time children were napping and interior noise was seemingly very low. Weekly Data Summary: After reviewing the outdoor noise data, there was only one day (October 10 th )where the Lmax was exceeded in the play area. These occurred during the hour intervals of 8:00 a.m., 11:00 a.m., and 3:00 p.m. This may or may not have been caused by construction noise. Interior noise levels seem to be driven by interior noise sources and activity within the Children s Center. Through some construction noise will be audible at times; it is having very little effect on interior noise levels. This concludes our findings based on the data collected for week 4-5. The measured results are attached in the tables following this memo. Please contact us if you have any questions or require additional information. Sincerely, SSA Acoustics, LLP Joel Esselstrom Senior Technician