$2\mathrm{.}1$ A certain mine intends to start a bord and pillar mining panel and thereafter perform pillar extraction on the same panel. On surface there is a farmer$$s water borehole. Design panel layout to ensure that the water table in the overburden is preserved. $(10$ marks$)$

Given: Bord width of $6$m and pillar width of $18$ m$.$ Depth below surface $140$m$.$ Thickness of dolerite sill $20$m intersected at $60$m$.$ Goaf angle $300,$ k$-$ratio $1\mathrm{.}5.$