METHODS FOR DEWATERING. PRESSURE RELIEF,. AND SEEPAGE CUTOFF
1- 1. General.
a. Tempomry dewatering systems. Dewatering and control of groundwater during construction may be accomplished by one or a combination of methods described in the following paragraphs. The applicability of different methods to various types of excavations, groundwater lowering, and soil conditions is also discussed in these paragraphs. Analysis and design of dewatering pressure relief and groundwater control systems are described in chapter 4.
b. Permanent dminuge systems. The principles and methods of groundwater control for permanent structures are similar to those to be described for construction projects. A method often used for permanent groundwater control consists of relief wells (to be discussed subsequently in detail) installed beneath and adjacent to the structure, with drainage blankets beneath and surrounding the structure at locations below the water table as shown previously in figure 1-2. The water entering the wells and drainage blanket is carried through collector pipes to sumps, pits, or manholes, from which it is pumped or drained. Permanent groundwater control may include a combination of wells, cutoffs, and vertical sand drains. Additional information on the design of permanent drainage systems for buildings may be found in TM 5-818-1/AFM 88-3, Chapter 7; TM 5-818-4/AFM 88-5, Chapter 5; and TM 5-818-6/AFM 88-32. (See app. A for references.)