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Downtown Project Goals:
- Repave the roadways.
- Repair the sanitary sewer system.
- Make drainage improvements.
- Upgrade pedestrian curb ramps to current standards
Public Engagement: Development of the project will include a significant public outreach and engagement process to help determine the scope of the project. This includes participation of a Design Advisory Committee. Community members will have opportunities to participate in a public engagement process, through stakeholder meetings, public workshops and City Council Meetings. Throughout the engagement process, design engineers will develop conceptual plans that consider stakeholder feedback.
Updated Timeline: The project schedule has been accelerated to every extent possible, with work possibly beginning the week of April 20, 2020. The estimated completion date is the end of August 2020. (Updated April 7, 2020).
Phase I: This phase of the project will focus on repairing the sanitary sewer system - a much needed investment in aging infrastructure and the protection of groundwater and environmental sustainability. This phase will also include repaving and upgrading pedestrian curb ramps to current standards.
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Three Methods of Repair
Harris, and Associates, the City's contractor on the project, conducted a survey, inspection, and assessments of the existing sanitary sewer mains and have identified several major deficiencies including cracks, broken and collapsed pipes, sags, and offset joints. To address these deficiencies, Harris, and Associates proposes three different methods for the rehabilitation of the pipelines taking into account the condition of the existing pipeline, type of repair needed, and impact on the downtown business area.
- Cured-in-Place Pipe method (CIPP) consists of inserting a polyester liner into the existing sewer main. Prior to performing CIPP, any defects in the pipe that requires correcting will be repaired by excavating down to the pipe and performing a spot repair. Watch a video about CIPP.
The CIPP method will be used on Gardner St, Corte Madera (between Gardner and Lower Alcatraz), Throckmorton (between Miller and Madrona) and where the sewer crosses under buildings.
- Trenchless Pipe Bursting consists of inserting a cone-shaped tool into the existing pipe, fracturing the existing pipe and pulling a new pipe through the existing pipe. Existing lateral connections will be reinstated after the new pipe is installed in place by an open trench. Watch a video about pipe bursting.
Engineers anticipate that the Pipe Bursting method will be applied to Throckmorton (between Corte Madera and E. Blithedale).
- Open Trench Pipeline Replacement consists of replacing the existing sewer main through excavation and backfill. This method is the most disruptive and only used where other methods are infeasible.
Open Trench work will take place on West Blithedale Avenue and Corte Madera Avenue.
- Timing: Construction will be phased, so that the impacts are concentrated in one segment of roadway at a time – usually 3-7 days in any one location. Construction will generally take place Monday-Friday, from 8 am to 5 pm. There may be some night work, depending on the construction phasing and community needs.
- Service Connections: During the sewer lining process, service connections will be temporarily closed off for a few hours. Every service lateral will be fully opened and back in service by the end of each workday.
- Odor: For locations that will be treated with the CIPP method, downtown community members may detect a chemical odor. This is the smell of styrene, a component of the resin used to saturate the sewer liner. This odor will quickly dissipate once the installation process is complete. Please click here for additional information.
- Additional anticipated impacts include some parking restrictions, traffic, temporary disruptions to delivery schedules and access, dust and noise. The City project team is committed to mitigating construction impacts and will work with individual businesses to make sure they are informed in advance of the work, and accommodations are made whenever possible to lessen disruptions to daily operations.
- Construction Tool Kit - Check out this resource for downtown businesses during construction.
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Engineering Design: Harris & Associates
Traffic Engineering: Parisi Transportation Consulting
Public Engagement: Plan to Place
Landscape Architect: RHAA
Construction Management: TBD
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