24-hour-a-day work for the Capitol Hill light rail station construction and tunneling is a go. The City of Seattle has approved Sound Transit’s application for permission to exceed legal noise thresholds during nighttime construction. The approval will allow the agency’s contractors to run machinery 24 hours a day at the Broadway construction site between John and Denny so that the tunneling process does not need to be halted at night. From the Department of Planning and Development’s document approving the variance:
The only way to comply with sound level limits is to prohibit tunneling during nighttime hours. To do so would cause unsafe working conditions, would increase the risk of voids in the soil and subsidence of the surface above the tunnel, and would produce a hardship to the public because it would take longer and add more cost to complete the project.
Appeals of the decision must be submitted to DPD by
May 3rd April 29 (DPD originally posted an incorrect date for this deadline) At a public hearing on the variance, only one community member spoke during the public comment portion of the meeting.
The noise variance specifically covers the hours of 10 PM to 7 AM on weekdays and 10 PM to 9 AM on weekends and holidays. At all other hours, the city’s regular daytime noise laws apply. Sound Transit has says that its contractors won’t enter the phase of construction the variance is required for until 2011.
The ‘variance’ in the process refers to the amount by which the sound levels can vary from the nighttime measured average for the area. As part of the application process, Sound Transit measured noise levels at areas near the station. Here are the levels Sound Transit measured from a meeting the agency hosted on the noise variance process:
The approval of Sound Transit’s application marks the first time DPD has processed a Major Public Project Construction Variance request. The new framework for major projects was approved by the City Council last March. The rules simplified the noise variance process for major public projects but also created safeguards including
Here is the full presentation on the noise variance that Sound Transit presented at a community meeting in February:
As part of the approval, DPD also considered the noise mitigation efforts Sound Transit has agreed to engage in including the large plywood walls being installed around the construction site and the banning the use of ‘tonal’ back-up alarms (beeep beeep beeep) on vehicles operating at night.