A trench 1 mile long is to be excavated to an average depth of 8′. The trench base is 4′. Vertical sides are 5′. The top 3′ of the trench are sloped at 1:1. What is the total amount of cubic yards excavated from the trench?

A trench 1 mile long is to be excavated to an average depth of 8′. The trench base is 4′. Vertical sides are 5′. The top 3′ of the trench are sloped at 1:1. What is the total amount of cubic yards excavated from the trench?