Discussion Post
• What must be considered when designing a dewatering system?
• Under what conditions would a slurry wall system be very effective?
• Under what conditions would a sinking caisson be effective?
• Under what conditions might you want to use cofferdams?
Problem
• Figure 9.21 is representative of soil conditions at a construction site. If you are the contrac-tor, select a dewatering method you would consider appropriate for each of the projects described below. Consider the information given in this chapter, earlier chapters and any other information that may be appropriate. Describe in detail how your system would be built and operated. Justify clearly any assumptions you make. Discuss what difficulties you may encounter and how you should plan for them. a. A circular reservoir 100 ft in diameter is to be built with a bottom slab 25 ft below present ground surface. The groundwater level must be held at least 2 ft below the slab until the reservoir is filled. b. A bridge pier with a driven pile foundation is to be built with the bottom of the pile cap 40 ft below present grade. The cap is 20 ft by 30 ft in plan view
• Repeat Problem 1 for the following projects with soil conditions as indicated in Figure 9.22. i. 1200 ft of an 18-in. sewer line is to be placed in a trench about 16 ft below ground surface. ii. A 30-ft-diameter concrete pump station is to be founded on the basalt rock at 65 ft in depth. iii. Conditions as in a, except that the pipeline is 28 ft below the ground surface.
The response must include a reference list. Using Times New Roman 12 pnt font, double-space, one-inch margins, and APA style of writing and citations.