When Sound Transit contractors arrived at 20th & McGraw back in June to install a dewatering well for the light rail tunnel below, the work was intended to last a matter of days. Today, six months later, ST announced plans to remove the pumps, generators and tanks that have closed down the street. From ST spokesman Roger Pence:
On Monday, Dec. 10, the pumps will be turned off and crews will begin removing equipment — the above-ground pipes, generators, control panels, and so forth. No Parking signs will go back up on McGraw to allow room for the trucks and equipment necessary to remove the pipe on the north side of the pavement.
On Tuesday, Dec. 18, the drilling subcontractor will arrive to begin decommissioning the wells — cutting them off below grade and filling them with grout, and then backfilling the holes.
There will be a break in the work over Christmas week, but beginning the first of the new year, the paving contractor will begin replacing all the concrete street pavement panels that were cut to put the system in place. That work will require that the no-parking signs go back up. McGraw is the route for school buses (going westbound) and the contractor will allow the buses to go through without having to detour.
Landscape restoration will be the last step.
The plan comes with a word of warning: working underground is always unpredictable, so call me maybe.
In other construction noise news, jack hammering continues to be heard near Eaton Place. While the cross-passage construction that rattled so many windows last summer is complete, some of the temporary “propping” shotcrete (spray-on concrete) for that work is still being demolished.
And since leaky concrete is in the news these days, some may be wondering why water is being pumped out of the tunnels in the first place. The tunnels do in fact have an exterior waterproof lining keeping groundwater out. However, portions of the tunnel walls had to be removed to create the emergency cross-passages — and for that work water had to be pumped away from the exterior walls. This was done both with pumps inside the tunnel and with the surface well at 20th & McGraw.
Light rail service is schedule to begin at UW Station in late 2016.