Volume 8 – Mechanical and Electrical Services - Malaysia Geoportal

Chapter 3 GROUND WATER FACILITIES
The best method of measuring the draw down is using the draw down meter.
On completion of pumping test, it is necessary to record the water level so that draw down can be
checked. If the water level fails to recover fairly close to the original SWL (Standing Water Level)
after the period of time similar to the duration of pumping, it is suggested that the recharge is not
sufficient to meet the demand.
3.12.4 Testing low yield bores
Low yield bores such as stock and domestic can be tested by any of the following methods. However
it should be recognised that test pumping is the most accurate method:
- Bailer test
- Airlift test
- Single stage pumping
Single stage pumping, the process is performed or conducted by inserting a submersible or shaft
driven pump in a bore. A minimum test period for single stage test is between 6 to 12 hours. It may
be necessary for the driller to do few trial pumping runs, and preset the pumping equipment so that
it will start at and maintain the required rate. Continuity pump test can be carried out up to 72
hours.
For further details, the SOP (Standard Operation Procedure) of the particular drilling equipment
should be referred to.
3.12.5 Testing high yield bores
Pumping water for a week is necessary. It is essential to do multistage of pump test water levels and
discharge rate and the time taken for each measurement are recorded through the test.
3.13 PUMPING DESIGN AND INSTALLATION
Low pressure pump- A centrifugal pump provides high volume flows suited to large diameter holes.
It will not provide the pressures necessary for deeper well.
Centrifugal pump requires little maintenance. The stuffing box or gland will require adjustment and
re-packing. The bearings will require greasing and the impeller may also be subjected to wear.
Medium pressures screw pump provide positive displacement pumps, pumping at medium pressures.
Helical screw pumps require adjustment of the gland and, at longer interval, replacement of the
rotor and drive link parts.
High pressures- multi stage pump, larger diameter impellers provide greater output. Adding stage
provides greater pressure. Pumps that have to overcome greater vertical head have more stages
than pumps working against lesser heads.
3.14 OPERATION AND MAINTENANCE MANUAL
Detailed specifications, diagrams, instructions and recommendation are provided in manufactures
manuals and bulletins. Most suppliers provide manuals which are an important reference when
inspecting the equipment and gives instruction on service/ maintenance requirements. Drillers should
ensure that they have all equipment manuals on site for easy reference in case of problems or when
ordering replacement parts.
March 2009 3-9