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The results concerning organic constituents and water composition are presented and commentedon below.Organic constituentsThe percussion borehole HFM05 has been used before as flushing water supply well andthe concentration of Total Organic Carbon (TOC) was known to be sufficiently low. Threesamples were collected during the drilling period and the TOC concentration was in the range3.4–6.4 mg/L. The flushing water well was used without further measures (e.g. using anactive carbon filter system for reduction of organic substances as was applied when drillingKFM01A /5/).Chemical composition of flushing waterThe flushing water was sampled at three occasions during drilling. As shown in Appendix C,the chemical composition of the groundwater from HFM05 changed somewhat during thedrilling period. For example, the chloride concentration decreased from 3,980 to 2,580 mg/Lfrom the first to the third and last sample.5.4.5 Groundwater sampling and analyses during drillingOne first strike sample was collected from a packed off section of KFM06C at 531.20–546.27 mborehole length during the drilling period, cf. Table 4-1.5.4.6 Registration of the groundwater level in KFM06CTo enhance the recovery of drill cuttings from the borehole, air-flush (mammoth) pumping wasapplied during the entire drilling period. The pumping capacity was checked by registrationof the groundwater level in the borehole, below plotted versus time of the drilling period(Figure 5‐16).110KFM06C10090Waterpressure [mvp]8070605040302004-27 05-02 7 12 17 22 27 06-01 6 11 16 21 26 month-daySTART :05/04/26 06:00:00 INTERVAL: >= 1 Hour STOP :05/06/30 17:59:59Figure 5-16. Variation of the level of the groundwater table in KFM06C during drilling.42