Question 11

a) 1. The disposal system is blocked.
    2. disposal area is insufficient.

b) To ensure that the installation remains as
    laid, is to leave the pipeline and tank full of water to prevent flotation.


c) Removing water from a trench or excavation.

d) 1. Well-point dewatering
    2. via a Diaphragm pump
    3. via a centrifugal pump
    4. Automatic sump pump
    5. Diverting the water.

e) To find the ground water level. This method can also be used with a pump to lower the ground water level in the vicinity of a trench, creating a reverse flow from the trench to the well points.

f)  1. A fixed point from which levels and distances may be taken. The datum will usually be fixed in relation to a bench mark.
    2. The level of the lowest point of the internal surface of a pipe or channel at any cross-section and related to the datum level.
    3. The highest seasonal surface of groundwater expressed as a distance below ground level.
    4. The density of a soil (required information when installing disposal fields or soakage holes)