DWAF Drilling specifications for KNP site at Phugwane
WATER RESEARCH COMMISSION PROJECT
GROUNDWATER AND WETLANDS
K5/1337
Drilling Specifications
- Preamble
The Water Research Commission is funding a research project to investigate the dependence of ecosystems on groundwater. The project team, led by CSIR, will be working at 2 field sites to characterise groundwater discharge to the natural environment.
These sites need to have established a groundwater monitoring network. These monitoring points are to be boreholes from which can be obtained water - levels and water samples.
- Locality
The site of interest for this contract is:
1) Phugwane tributary site close to Shingwedzi camp in the Kruger National Park.
- Access
Access is possible with a standard vehicle mounted drill-rig. New access roads will not be permitted, as the site is within a Protected areas. The drill-rig will need to operate close to existing tracks but will need to be able to drive on sand in a dry river bed.
- Geology
Boreholes will be drilled into unconsolidated alluvial sand and bedrock of granite, gneiss and basalt. The formations may include the Letaba formation, the Timbavati gabbro and the Goudplaats gniess.
- Number of boreholes
It is expected that 6 boreholes will be drilled, to a final depth of 10 to 70m.
- Depth of boreholes
The boreholes are expected to be 10m x2, 20m, 30m, 40m, 60m. The final depth will be decided by the on-site hydrogeologist. The total meterage is estimated at about 170m.
- Details of borehole
7.1Hole size
The inner diameter of the final casing installed should be greater than 120mm in order to accept a 100mm sampling pump. The driller must thus ensure that the drilling diameter chosen can accept the required casing.
7.2Casing size and type
The internal diameter of the final casing must be greater than 120mm. The casing material must be PVC. Due to the risk of damage by veld-fires 2 to 3m of steel casing (with lockable cap) must be installed at surface.
7.3.Slot sizes
It is expected that screens will be required at between 2m and 10m per borehole. Slotting should be 0.5mm , ~100mm spacing and 4 sides of the casing. The on-site hydrogeologist will specify the section of the borehole to be selected for screening.
7.4End-cap
End-cap must be installed.
7.5Gravel
A crushed quartzite chip must be used as a formation stabilizer .
7.6Surface construction
The steel casing must stand 300mm ±50mm above ground. A borehole end-cap must be attached. The ground surface around the casing must be mounded to 50mm above ground surface and this mounding must extend 100mm beyond the hole created by drilling. Excess drill chippings must be removed and properly disposed of off-site of the Nature Reserve.
7.7Clean-up and general clean behaviour
As both sites are located within sensitive Nature Reserves, a high standard of clean behaviour will be required both during and after drilling. A rigorous but not over onerous EMP will be developed and put in place for drilling operations.