A 100 m x 25 m detention pond is proposed for a 7.5-ha site. The detention pond is 2.0 m deep under control (pre-storm) conditions and the water-quality depth is 2.0 cm. Storage in the detention pond is to be discharged offsite via a triangular weir whose vertex is at the control elevation, and the flow rate over the weir, Q [m3/s], is given by: 5/2 Q H  0.08 where H is the height of the water surface above the vertex of the weir [m]. The average annual rainfall at the site is 120 cm, and the average runoff coefficient is 0.75. Determine the evacuation time and the average detention time in the pond.