Observation

Most of the candidates were able to:

• List the types of sewer;
• Sketch the sanitary appliances.

However, some of them could not describe the waste collection points: cesspool, soakaway and septic tank.

The required responses to question 3 are given below.

(a)   
(i)  DEFINITION OF SEWER
       A sewer is a large sewage collection channels where drains from building discharge  into.                                                                                                                                                                             
(ii)   TYPES OF SEWER:

• Public sewer,
• Private sewer.                                           

(b)       
(i) Cesspool: is an underground collection point usually used where the site condition
makes construction of septic tank and soak away impossible. It is a large
concrete/brick  tank water tight with inlet pipe but no outlet pipe. It is evacuated by
sewage trucks when filled.

(ii) Septic tank: this is design to retain sewage for a period adequate to allow solids to
settle to the bottom of the tank where they decompose. The tank has inlet and outlet
unlike cesspool. It is discharge into soakaway when it is filled.

(iii) Soakaway: are sewage collection points which are dug in permeable soil so that the
water that comes into it is absorbed into the soil. The soakaway is usually filled with
large  broken stones to allow for percolation of waste water into the soil.                             

                                                                                                                               
(c)     Sketch of the following sanitary appliances:
(i) Kitchen sink;