$3-3$ To construct a $28,000m^3$ embankment, material from a borrow site with an average wet unit weight of $17\mathrm{.}8k\frac{N}{m^3}$ and water content of $10\mathrm{.}0\%$ is considered. The Standard Proctor test results on a representative sample of silty sand from the borrow site is presented below. The specification requires a minimum of $95\%$ relative compaction.

$($a$)$ Recommend a range of water content to achieve the proper compaction.

$($b$)$ Estimate the degree of saturation for the laboratory obtained maximum dry unit weight assuming a specific gravity of $2\mathrm{.}75$ for the solids.

$($c$)$ What would be the minimum volume of the borrow material that needs to be imported to construct the embankment?