Question $1$

Seepage is occurring through the sandy layer underneath the concrete dam shown in Figure $1.$

Figure $1$

The following was recorded on site and laboratory:

Upstream water level $(H_1)=20m$

Downstream water level $(H_2)=5m$

Thickness of the sandy layer $=1\mathrm{.}5m$

Length of dam $(L)=66m$

Diameter of soil specimen $($tested in the lab for permeability$)=150mm$

Length of the specimen $=300mm$

Porosity $=39\%$

Water collected in $22$ seconds $=83ml$

Pressure head $($Constant$)=19\mathrm{.}2cm$

Specific gravity of sand $=2\mathrm{.}66$

Determine:

a$)$ Rate of seepage per unit length of the dam $($in $\frac{m^3}{h}\frac{r}{m}).$

b$)$ Seepage velocity in $\frac{m}{s}.$

c$)$ Quantity $($in liters$)$ of seepage per day if the dam is $410m$ long.