Water is falling on a surface, wetting a circular area that is expanding at a rate of 6 mm2/s. How fast is the radius of the wetted area expanding when the radius is 170 mm

Farmer a has a deep well and needs a lot of water for her animals and crops. her neighbor, farmer b, has a shallower well. he needs less water than farmer a because his farm is smaller. in years of drought, sometimes farmer b can't get any water from his wells. what can farmer b do to decrease the likelihood of his well running dry?