Design standards No. 13 : Embankment Dams. Chapter 16 - Cutoff Walls

Construction of conventional rolled earthfill cutoff trenches can be a prohibitively expensive operation, depending on the required depth and on existing natural groundwater conditions. The recent trend has been toward application of cutoff walls in control of seepage for embankment dams. Cutoff walls can be constructed by a variety of methods that do not require foundation dewatering and greatly reduce the amount of excavation from that required for a rolled earthfill cutoff. This chapter is intended to present general design considerations for the most widely used types of cutoff walls currently accepted as viable alternatives to the more conventional rolled earthfill cutoff trenches. This chapter provides general considerations for the design and construction of the most commonly employed types of cutoff walls currently used in embankment dam applications. Detailed design criteria have been included when appropriate. However, in keeping with the purpose of this chapter, emphasis has been placed on providing general considerations and information that will assist the designer in developing of the most cost-effective design for a given site.