Borehole Pump Testing Sample Clauses

Borehole Pump Testing. This activity provides data for an evaluation of the yield potential of the borehole and the groundwater resource from which it draws its water. The testing must be accomplished by a suitably experienced testing contractor again functioning under the direct supervision of the principal appointed entity/ team responsible for the siting of the borehole and the supervision of its drilling and construction. The following yield tests are to be undertaken under the supervision of a Geo-hydrologist to determine the sustainable yield of the boreholes and to determine the size of submersible pumps. The following points are mostly applied to production boreholes: • 3 to 4 times step drawdown tests of 90 minutes each. • 24hours constant rate pumping test. • Recovery test (>95%). • Groundwater samples to be collected in the appropriate bottle provided by a SANAS accredited laboratory. An EC/pH probe is to be used on-site to measure field parameters, and Groundwater samples are to be submitted to a SANAS accredited laboratory for Physio-chemical and bacteriological analysis according to SANS 241:2015 water quality guideline. A water sample should be collected from the end of the discharge pipeline no sooner than 15 minutes before the scheduled end of a pumping test whether this is of a calibration, stepped discharge, or constant discharge nature. This is to ensure that a water sample is collected in case testing does not proceed to include either one or both latter two types of tests. The standard amount of sample normally collected is in a clean, sterilised plastic bottle of capacity 240 ml or greater and equipped with a watertight screw-on cap. This is the standard-issue sample bottle provided by the DWAF. Depending on the analysing laboratory's requirements, however, a sample of up to two litres in volume may have to be collected. The Geo-hydrological Consultant to advise on this matter in instances where the contractor is required to collect samples, in which case the consultant to provide ampoules containing preservative chemicals if required. All other materials such as sample bottles, tie-on labels, and sample custody forms are to be provided by the contractor. Table 4-11. The period after which a constant discharge test may be considered completed. CONSTANT DISCHARGE TEST DURATION ALLOWABLE TIME ELAPSED TO BREAKDOWN 24 hours 20 hours (equivalent to 80% of total time) 36 hours 30 hours (equivalent to 83% of total time) 48 hours 38 hours (equivalent to 79% of tot...