During percussion drilling
(A) Ground water observations are hindered due to entry of the slurry in the soil below the
bottom of the hole
(B) Caving or mixing of strata are caused in soft soils or cohesionless soils
(C) The soil to a considerable depth below the bottom of the hole gets disturbed
(D) All the above
(A) Ground water observations are hindered due to entry of the slurry in the soil below the
bottom of the hole
(B) Caving or mixing of strata are caused in soft soils or cohesionless soils
(C) The soil to a considerable depth below the bottom of the hole gets disturbed
(D) All the above