An aquifer has a gradient of 0.00115 , a hydraulic conductivity of 1,000m/day, and a porosity of 0.23 . Consider 3 monitoring wells, each located at the vertex of an equilateral triangle. The distance between any pair of wells is 300m. The head at each well, referenced to some common datum, is as follows: well 1,100m; well 2 , 100.3m; well 3,100.3m. a) Calculate the average linear velocity of the groundwater in m/day b) If the front edge of a plume is perfectly straight, how long in days would it take to travel to well 1 after first arriving (simultaneously) at wells 2 and 3 , assuming a retardation factor of 2