Sound TransitCapitol Hill Station

Major Public Project Noise Variance

February 11, 20106:30 p.m. – 8:30 p.m.

SCCC

University Link• 3.15-mile light rail extension

– Capitol Hill Station– UW Station

• Schedule– Construction: 6.5 years– Open for Service: 2016

• Adds 70,000 daily riders, 114,000 system wide (2030)

Expanding light rail• 16 miles and13 stations in service• 36 additional miles funded

Capitol Hill Station

• Underground station with 3 entrances

• Staging area - station and tunnel excavation at site

• Ridership: 14,000 daily boardings

• Travel time: – 3 minutes to downtown

Seattle (University St.)– 3 minutes to UW Station

Capitol Hill Site Noise Variance

• Sound Transit has applied for variance from City of Seattle

• Noise variance establishes noise limits for contractor work between 10pm - 7am weekdays, 10pm - 9am weekends, holidays

• Variance would allow up to 26 months of nighttime activity

• Daytime construction activities will comply with City’s construction noise limits.

Previous Outreach on Noise Variance

• June 17, 2009:– Initial nighttime construction plans

and noise predictions• October 8, 2009:

– Updated noise measurements– Proposed mitigation measures– Noise variance application and

process– Added trucking restrictions on 10th

• Jan 14, 2010: – Review of nighttime work– Status update on variance– Wall height on 10th Ave. increased

Why Work at Night?

• Continuous tunneling has lower risk

• Certain activities are required for tunnel worker safety

• Maximizes project safety, efficiency, duration and cost

Construction Schedule

Nighttime construction

activity

What Goes on at Night?

Type of Equipment:• Tunnel ventilation fans, pumps,

air compressors• Generator• Vehicles

– hauling and delivery trucks– muck haul trucks– front-end loaders, backhoe– loaders, excavators

• No high impact equipment (jackhammers, concrete saws,etc.) will be allowed at night

Existing Nighttime Noise Hourly nighttime average (midnight – 5 AM)

54 dba

63 dba 53 dba

54 dba

63 dba

Nighttime Noise Limits with Variance 6 dba increase from existing

60 dba

69 dba 59 dba

60 dba

69 dba

• Surround the site on all sides

• 8 to 24 feet high, plywood construction

• Help contain noise, dust, and debris

8’ wall12’ wall16’ wall24’ wall

KEY

Noise Mitigation Requirements - Walls

Stationary equipment (compressors, generators) enclosed in noise reducing material

Noise Mitigation Requirements - Equipment

• Nighttime truck operations– No tonal back up alarms– Engine idle limit of 5

minutes– No compression brakes– Muck haul bins lined with

noise dampening material– Haul trucks prohibited on

10th Ave during night hours

Noise Mitigation Requirements - Trucking

Monitoring and Responding to Complaints

• Continuous sound monitoring stations • 24 - hour construction hotline: 1-888-298-2395 • Independent response by City noise abatement

specialist • City, ST and contractor will investigate, determine how

to prevent future incidents, and respond back to caller• City review of variance after 1 year

Next Steps

• Comments from tonight’s meeting are recorded and considered in the review of the application

• City will decide whether to approve the noise variance within 60 days after public comment is received

• Contractor will prepare a detailed noise management plan to comply with variance conditions

• Tunnel construction activities begin – late 2010