The average winter precipitation in Manchester is $85$ mm per month.

For the chemical plant you are working at$,$ this equates to an average rainwater flowrate of $5$ L s$\mathrm{ –}1$ on rainy days to be transported to a nearby water treatment plant.

i$.$ An asphalt-lined, square drainage channel $($width $=25$ cm$),$ is in place. For a normal flow depth of $15$ cm$,$ what slope is required?

ii$.$ There is a serious fire at your chemical plant, containment of which requires $600$ L min$–1$ of water. Will all the used firewater be contained and transported within the same drainage system?