Question

As a very general guideline it is recommended that the bottom of the pit should be at least _______ above groundwater level.

(a) 0.5 m

(b) 2 m

(c) 12 m

(d) 20 m

I have been asked this question in an interview for internship.

Question is taken from Design of Septic Tanks topic in section Road Estimating, Sanitary and Water Supply Work of Civil Engineering Drawing

Answer 1

Correct option is (b) 2 m

Best explanation: As a very general guideline it is recommended that the bottom of the pit should be at least 2 m above groundwater level, and a minimum horizontal distance of 30 m between a pit and a water source is normally recommended to limit exposure to microbial contamination.[1]However, no general statement should be made regarding the minimum lateral separation distances required to prevent contamination of a well from a pit latrine. For example, even 50 m lateral separation distance might not be sufficient in a strongly karstified system with a down gradient supply well or spring, while 10 m lateral separation distance is completely sufficient if there is a well developed clay cover layer and the annular space of the groundwater well is well sealed.