Homework #15 Distribution Date: 10-30-2023. Due Date: 11-02-2023. 1. An exploratory drill hole was made in a stiff saturated clay. The sand underlying the clay was observed to be under artesian pressure. Water in the drill hole rose to a height of 18 ft above the top of the sand layer. If an open excavation is to be made in the clay, how deep can the excavation proceed before the bottom heaves? 25 ft 18 ft 16 ft Exploratory drill hole Saturated clay Sand NOTE: Show all the calculation steps! G = 2.7 Moisture content =w=40%