Drilling guideline

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The route to successfully and correct implementation of water supply projects.

When a request for a water supply project is received the following route is strongly recommended to achieve the required and most cost benefit results: Please take note and adhere to the following: Do not advertise or implement the project before the availability of the required water has been confirmed,

STEP 1: Collection of available information. The first phase should be completed by the implementing agents.

Collect all available information to determine the budget that will be required for the groundwater source development. This information includes the following: Population to be served, Total daily abstraction required to solve the water needs (Level of supply 25, 60, 100 l/c/d etc.).

  1. Determine the boundaries of the study area (Project boundaries),
  2. Check and download all available information for the designated Project area from the GRIP-Website: www.hriplimpopo.co.za
  3. Compile a list of all the borehole numbers found on the GRIP Website within the designated project area and request additional information from GPM (015 297 3338) and/or from groundwater Consultants through GPM,
  4. Forward the selected or designated project boundaries to GPM (015 297 3338) and/or groundwater Consultants through GPM and request a search for any additional boreholes not yet reported to GPM,
  5. Request from GPM (015 297 3338) the name of the institution to whom these borehole numbers were allocated to,
  6. Contact these institutions and request them to search for additional information on the borehole numbers allocated to them but not yet reported on,
  7. From all the collected information identify all the tested boreholes with a recommended operational pumping rate. Calculate the available daily abstraction from these recommended operational rates, but as a minimum for motorized equipment, only use those yielding more than 14m3 per day (0.5l/s for a 8-hour duty cycle or 0.2l/s for a 24-hour day). If no tested boreholes could be identified use boreholes that have listed yield (blow yield, etc.),
  8. Compare the calculated available volume with the required volume and determine the shortfall or surplus water,
  9. Use the provided co-ordinates of the boreholes used in the above calculation and plot them on a map to verify their positions in order to ensure that they don’t include re-drills or are too close (within 300m) to other selected boreholes,
  10. When the demand is met, appoint a groundwater consultant to verify the water levels and depths listed and if similar to the data provided by GPM, implement the project. If not consider re-testing of these selected boreholes,
  11. From the list of identified boreholes, their equipment, their recommended operational yields and/or blow yields of non-recommended boreholes, compile a list of boreholes with apparent adequate yields to meet the demand,
  12. Should no possibility for testing of existing boreholes exist only then should a groundwater consultant be appointed to investigate the possibilities for utilizing groundwater sources,

STEP 2: Appointment of groundwater consultants

Request quotations or cost estimates from groundwater Consultants:

  1. The appointment of a groundwater Consultant can be made prior to collecting of available information (STEP-1) but due to the availability of information (GRIP) this can be done by the implementing agents,
  2. When requesting a cost estimate, divide it into the following six phases,
    1. Phase 1-Data collection, Liaison, site visit, verification of information etc.-This phase could confirm that no further drilling is required,
    2. Phase 2-Testing of existing boreholes – The information obtained from the testing results could also confirm that no further drilling will be necessary,
    3. Phase 3-Geological and Geophysical investigation. This phase should include the reporting on the possibilities of obtaining water within the supplied boundaries or alternative areas (Possible drilling targets outside the designated project boundaries or a more regional approach),
    4. Phase 4-Drilling of additional boreholes. The Consultant can include the contractor’s cost as per approved DWAF-Tender rates for the specific area, and appoint the contractor accordingly. The contractor should preferably receive a separate order or appointment on condition that the Consultant verify and sign certificate to approve quantities utilized,
    5. Phase 5-Testing of new boreholes. The Consultant can include the contractor’s cost as per approved DWAF-Tender rates for the specific area, and appoint the contractor accordingly. The contractor should preferably receive a separate order or appointment on condition that the Consultant verify and sign the certificate to approve the quantities utilized,
    6. Phase 6-Final Reporting. A technical report with conclusions and recommendations of which a copy must be provided to GPM for the purpose of updating of the regional database. This phase could include groundwater modeling.
  3. With the request for quotations or cost estimates, it is important to provide accurate quantities in order to obtain a representative budget. From information available (Water levels, depths drilled etc.) within the designated project area, the boreholes required to obtain the demand, the depths to drill, casing to be installed etc. can be calculated and accurate cost estimates determined for Geohydrological Consulting, Drilling and Testing contractors,
  4. The consultant can be appointed as per phase provided above with a report on the results and recommended actions on completion of each phase or for the entire project with a final report on completion of the project,
  5. Appointing Consultants and collecting information will ensure funds are not wasted on collecting information that is already available. Proper supervision will also ensure boreholes are constructed to the required standard and recommended for a correct daily abstraction to minimize failure and maintenance cost but maximizes sustainability.

STEP 3: Possible cost saving decisions.

Consider the following during the implementation of projects,

  1. Often projects are implemented within villages where the chemistry of borehole water has been analyzed and known to be of poor quality. This should immediately be identified and noted from the “information collection phase” prior to the appointment of consultants and/or contractors. Alternative areas or geological structures with better quality water should be investigated rather than drilling more unusable boreholes,
    1. Un-equipped, strong boreholes with poor water quality does exist and the possibility of installing purification plants should be investigated,
    2. Mixing the water from two different boreholes i.e. one with poor quality and one with good quality could result in a supply suitable for human consumption. In many instances, the reason for water classified as Class 3 or worse is due to specific elements. (Borehole “x” is recommended for 50 000 liters per day but is Class 3 due to a high Nitrate count of 28mg/l but has a Chloride value of 45mg/l, borehole “y” is recommended for 25 000 liters per day and is Class 4 due to a high Chloride value of 1250mg/l but has a Nitrate count of 1mg/l. Mixing will reduce the Nitrates to 19mg/l (Class 2) and the Chloride value to 447mg/l (Class 2),
    3. When strong boreholes with poor water quality are drilled, it should not always be removed from the list for equipping. In some villages, boreholes with totally unsuitable water quality are still being used as it is the only water available. These boreholes could be replaced by boreholes with much better quality water although the water quality might still be above the acceptable limit for human consumption. A good example of such a case is at Matoks village where the borehole in use had a Nitrate count of 380 mg/l whereas a stronger newly drilled borehole had a Nitrate count of 35mg/l. The latter was equipped to replace the old hole as it had a 90% better quality although it was still classified as Class 4 water)
  2. The testing of existing boreholes often reduces project costs. Even if the existing boreholes are not high yielding, the information obtained is valuable for the phases to follow. (During a project conducted at the Mecklenburg village, a broken hand pump was located on a geological structure interpreted from the AstraSAT imagery and a decision to test this borehole proofed to be correct and very valuable. This is currently the strongest borehole supplying water to the village (This hand pump was constant yield tested at 16l/s and recommended to supply 340 m3 per day),
  3. Attempts to obtain good yielding boreholes failed at many villages but new project are often implemented at these villages again. Most of these villages are situated within a low yielding geological environment and in such cases a regional approach should be followed to investigate potentially better looking geological targets further away.
  4. Many good geological structures occur all over the province and in many instances pipelines are often build or planned alongside these or parallel to these features. Pipelines should rather be perpendicular to these structures to supply villages within areas of low groundwater potential. (A fault or water bearing linear structure also transport water(can replace the pipe line) and can save money through drilling a borehole closer to each village alongside this feature instead of building a pipe line alongside this structure for kilometers – (Tshipese fault etc.)