A new retail store is being planned for a site that contains 40 ft of soft clay (cv = 0.075 ft2/day, = 100 pcf).

A new retail store is being planned for a site that contains 40 ft of soft clay (cv =
0.075 ft2/day, γ = 100 pcf). The clay layer is overlain by 15 ft of sand (γ = 112 pcf)
and is underlain by dense sand. The groundwater table is found 5 ft below the ground
surface. The structure is expected to add an additional load of 2000 psf throughout
the clay layer. To monitor the pore pressure dissipation within the clay during
consolidation, standpipes are installed 10 ft, 20 ft, and 30 ft within the clay layer.
Determine (a) the height of the water, with respect to the base of each standpipe, and
(b) the effective stress at the depth of each standpipe, at the following times:

 Before the structure is constructed.
 Immediately after the structure is constructed.
 5 years after the structure is constructed.