A small community with $20,000$ residents and has a landfill to manage its solid wastes. Assuming the waste generation rate is $3\mathrm{.}0$ lb solid waste per capita per day, the landfill is expected to have a remaining life expectance of $15$ years. If this town decide to build a large furniture factory that will produce $20$ tons of solid wastes per day, what will its life expectance be$?$