District 1 City Councilmember Lisa Herbold offered some information about the status of the West Seattle Bridge including the nature of what kind of concrete is required and what is involved in making it.

Earlier this week—March 23rd—marked just over two years since the closure of the West Seattle Bridge. I want to take a moment to acknowledge how difficult this has been for residents and businesses on the peninsula and Duwamish communities.  Getting the bridge open as soon as possible remains a high priority for all of us.

Concrete

The need to obtain the specialized concrete that can hold more than 20 million pounds of force and sustain that strength for decades, has been the key issue impacting the schedule.

The return of concrete mixer drivers to work at some companies has provided an opportunity to source concrete needed to guide and anchor steel cables needed for the West Seattle Bridge repair. I appreciate the willingness of concrete mixer drivers to return to work, despite the strike not being resolved.

Of the companies that mixer drivers have resumed work at, only Cadman can provide the specialized concrete required for the bridge. In mid-week, SDOT let me know that the next step was to receive a concrete mix design from Cadman, which will need to be certified by the Materials Lab at SPU.

The concrete mix design was received yesterday from Cadman and it is now at the Materials Lab (at Seattle Public Utilities) for certification.  I checked with SPU about the certifications process, and how long it might take.

Regarding the process, the Materials Lab “receives a package of proposed concrete mixes from our Contractor.  In that package are proposed concrete mix proportions, certifications, material test results and product information that Materials Laboratory staff compares with the City of Seattle Standard Specifications, as well as project specific specifications, to determine if the proposed mix(es) are compliant and suitable for the proposed purpose.  There are several possible outcomes of this review, from outright rejection to unconditional acceptance. It is not uncommon to return the submittal and ask for more information before final disposition of the proposed mix(es) is made.  Concrete mixes are not approved until the SPU Materials Laboratory is comfortable that they comply with all applicable standards and that they can be mixed, transported and placed to achieve project design criteria and provide lasting service.”

The Materials Lab noted they received the proposed concrete mix design late yesterday.  They helpfully noted the need to expedite review.  They have let me know that they expect to have the review for the proposed mix done in fairly short order.  I appreciate their recognition of the importance of this project and willingness to prioritize this work.

They also emphasized they are working with the project structural engineer in the review for concurrence.