What is the minimum separation distance between this potential explosion site $($PES$)$ and exposed site $($ES$)?$

$42ft$

$71ft$

$84ft$

Distance $=?$

Operating building $A$

Operating building B

$143ft$

HD $1\mathrm{.}1$ NEW $=500lbs$

HD $1\mathrm{.}1$ NEW $=100$LBS