2. (15) A 10-story steel-frame office building with a 200ftx 200ft foot print is to be built on a site underlain by alluvial sand and silts. These soils are fairly uniform and probably have good engineering properties. The building will have one 15ft deep basement and probably be supported on either a mat foundation located 5ft below the bottom of the basement, or a deep foundation extending 60ft below the bottom of the basement. The ground water table is about 25ft below the ground surface and the bed rock is several 100ft below the ground surface. There is no accessibility problem at this site. a. How many exploratory borings will be required, and to what depth should they be drilled? b. What type of drilling and sampling equipment would you recommend for this project? (From Chapter 3 of the text book)