Public safety not served by stadium sites
Orting residents have been cautioned about Mr. Rainier. But King County has remained silent regarding the slushy soils beneath the Kingdome and the Ackerley site. Granted, that is typical for a county that didn't even issue warnings about hot dogs or ceiling tiles.
For potential seismic instability, it is unlikely that any place in the state is more unsafe than Ackerley/Kingdome. And even though the City of Seattle has classified their highly liquefiable soils as "Environmentally Critical," the city also has remained mum.
Two soil consulting firms, Shannon/Wilson and Hart Crowser, have warned both the county and the Public Facilities district (Mariners Stadium Board) about the weakness of the underlying conditions.
While offering no guarantees, Shannon/Wilson recommends that Mariner pilings be sunk 15 to 20 feet into the relatively firm "glacial till" that ranges from 60 to 105 feet below the Ackerley surface, and that the pilings be protected by columns of gravel.
In contrast, Kingdome pilings have no gravel protection, and their till penetration was both slight and uneven. For example, a random survey of city-held records for 76 (of the 1,000) perimeter pilings shows these penetrations into the glacial till: 5 feet: seven pilings; 4 feet: one piling; 3 feet: one piling; 2 feet: 13 pilings, 1 foot: 17 pilings; 3 to 9 inches: 35 pilings; and 0 penetration: 2 pilings.
Further, after being driven by a pile driver to 10 or 15 feet below the surface, all 76 pilings then sank, on their own, with no further pile driver blows, through the underlying slush for collapses averaging 30 to 40 feet. Those 76 pilings--and probably all 1,000--have no lateral protection from the dangerous contrast of quake motions in the 30 to 60 feet of slush and alluvium between top and bottom. Based on those figures, I have asked Mayor Rice to order an analysis of the Kingdome pilings, to determine whether the structure should be condemned.
Next door, at Ackerley, the slush is nearly twice as deep, and twice as dangerous. For both sites, Shannon/Wilson has warned that, in a serious quake, the pilings could be subject to "curvature" and "displacement." No one should be seated, on the field, or in the showers at the moment of piling "displacement."
The state law creating the Mariners funding package insisted the new stadium was required for "public safety." Not even Gary Locke can guarantee that epicenters will remain in Duvall, or that we are not in year 495 of a 500-year quake cycle.
"Public safety" is not best served at either the Kingdome or Ackerley sites. Even Orting is more cautious.
Baxter Ward, Woodinville