3 ms·
The water table in Seattle is very high, about 4 feet in that area. So at the point of the blockage they are under 40 feet of water. Every ~33 feet of water is
by cincinnatus 13y ago
The water table in Seattle is very high, about 4 feet in that area. So at the point of the blockage they are under 40 feet of water. Every ~33 feet of water is an extra atmosphere of pressure.
- InclinedPlane 13y agoThe tunnel is not filled with water though. See abduhl's answer for the correct response.
- msandford 13y agoThe finished tunnel isn't filled with water because it's lined with concrete. The unfinished tunnel might be filled with water if it wasn't for the pressure that the TBM maintains at the cutting face.
- avn2109 13y agoNot "might." Absent face pressure, the tunnel would definitely be filled with water. This is precisely why they've gone to the trouble of inventing slurry face TBM's and building a recirculating slurry plant on the topside. Hard rock TBM's are much cheaper because they can get away without doing any of that.