A rectangular excavation is $80$ m long and $40$ m wide. The groundwater level is $1$ m

below the surface; an impermeable stratum lies at a depth of $13\mathrm{.}5$ m$.$ The average

permeability of the aquifer is $5*10-4$ m$/$s$.$ The excavation is to be $5\mathrm{.}5$ m deep. The

lowered groundwater is to be at least $0\mathrm{.}5$ m below the base of the excavation.

a$)$ Find Qtot for an equivalent circular excavation. $($You may start assuming h$0=4$

m$)$

b$)$ Estimate the number of wells required for r $=0\mathrm{.}10$ m$.$ Check the value assumed

for h$0$ and improve it if required, revising Qtot.

c$)$ Locate the wells around the excavation and check the lowered water level at the

most critical point using Forchheimer$$s equation.