1. 1. Sheet Pile wall
   2. Core wall + Sheet pile wall or Cut off wall
   3. Core wall + Cut off trench
   4. Core wall + Impervious blanket at the upstream surface
   5. Flattening the downstream face
   6. Rockfill toe on the downstream
   7. Horizontal drainage / filter on the downstream side
   8. Providing coarse section on the downstream face of the dam

There are three possibilities:

1. Only pervious soil is available:

1. Pervious dam body and base is impervious
2. Pervious dam body and base is pervious
3. Pervious dam body and base is pervious to a limited extent and impervious onward

2. Only impervious soil is available:

1. 1. Impervious dam body and base is also impervious
   2. Impervious dam body and base is pervious

3. Pervious and impervious both types of soil are available:

1. Pervious dam body, base is pervious upto some extent and impervious onwards
2. Pervious dam body and base is pervious
3. Pervious dam body and base is impervious

Design of dam filters

Terzaghi's rules for design of dam filters

Perform sieve analysis test on the material from dam body and filter base materials and draw gradation curve for both.

1. D15 (f) / D85 (s) < 5
2. D15 (f) / D15 (s) > 4 upto 20
3. D50 (f) / D85 (s) > 25
4. Filter material should be well graded
5. Gradation curves for both materials should be approximately parallel
6. All materials should pass sieve of 3" and not more than 5% passing sieve no. 200