I wanted to send a quick note to let you know the latest information about settlement in Pioneer Square.
We have told you about our settlement monitoring system that we installed as part of the SR 99 Tunnel Project. As we publicly announced last Friday, STP surveyors detected over one inch of ground settlement near the pit Seattle Tunnel Partners is building to access and repair the tunneling machine. We have also seen settlement on the Alaskan Way Viaduct and some of the buildings that we are monitoring; the amount of settlement lessens in the surrounding area.
Most of the settlement we’ve detected has been uniform, which usually means little to no damage to buildings and utilities. Engineers have been walking through the Pioneer Square neighborhood since we first learned of the new settlement. They have not seen any signs of new damage so far. An inspection team that includes an architect with historic building experience has been conducting interior building surveys since Monday and will continue over the next couple of weeks. If you have seen any recent changes in your building, such as new cracks or lengthening of cracks, sticking doors and windows or utility problems, please email us so we can set up an appointment.
Additionally, we have stepped up our monitoring frequency. Deep survey control points are checked approximately every other day and buildings and various points on the ground are surveyed once a day. Since Dec. 1, STP has not seen any appreciable change in settlement. Based on this, it appears that additional settlement is not occurring, though we will continue to closely monitor the situation.
At this time, Seattle Tunnel Partners is maintaining their dewatering system – and water levels remain static. However, they have stopped excavation until we can verify the new data. We will let you know when excavation resumes.
As for the crack in King Street, Seattle Tunnel Partners checked the site with ground-penetrating radar Thursday afternoon. While we are still awaiting the report, no voids were detected under the pavement.
If you have concerns about your building, property or utilities, please do not hesitate to call our hotline at 1-888-298-5463 or email us at firstname.lastname@example.org.
Todd V. Trepanier, PE
Alaskan Way Viaduct Replacement Program