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ISO 5667-22-2010 pdf free download
ISO 5667-22-2010 pdf free download.Water quality — Sampling — Part 22:Guidance on the design and installation of groundwater monitoring points
Qualité de I’eau — Echantillonnage — Partie 22: Lignes directrices pour Ia conception et I’installation de points de contrOle des eaux souterraines.
4.2.4 Hydrogeological considerations
The depth to the water table influences the choice of drilling method, casing and screen materials. For the drilling technique, some materials may behave differently when saturated or unsaturated, and the drilling penetration rate and strata stability may be affected. When drilling with a percussive rig, there may be a requirement to add water or flush to aid the recovery of drill cuttings.
Some casing materials are limited by the length that can be suspended in a borehole before failure occurs. usually at the joints. Many plastics have some buoyancy in water WhiCh means that the suspended length can be increased in a saturated borehole compared to a dry one.
Artesian conditions affect the drilling method, the headworks design, and the installation method. Special precautions should be taken where artesian heads are expected, as uncontrolled release of water could affect the environment or create a health and safety risk. Where artesian conditions are likely, specialist drilling advice should be sought.
Locating the water table and understanding its likely fluctuations are necessary to establish the depth and length of the screen. The location of the screen should be linked to the objectives and should be cut or preferably manufactured to size. Casing and screen sections come in standard lengths, typically 1 m or 3 m; if necessary, these can be cut to size on site.
In genera), monitoring zones are located within permeable horizons and need to be accurately located, In multi-layered aquifer systems and where contamination is present, care is required to prevent different permeable horizons from becoming connected during drilling or installation. The drillers awareness of the objectives prior to the start of work benefits data recording during drilling and ensures that important changes in lithology and water strike information are not missed. The hydraulic properties of the strata affect the filter pack and screen design, the choice of development technique and the potential for loss of flush during rotary drilling, and may affect the choice of drilling technique. A guide to material selection Is given In 4.5. Where the groundwater chemistry could be hazardous to health, additional health and safety requirements may be necessary. Groundwater conditions may also affect the choice of backfill and these should be considered before finalizing material selection.
The presence of separate phases (LNAPLs and DNAPLs) in the monitored horizon influences the design of the screen, the choice of casing material, and the drilling technique. The presence of non-aqueous phase liquid (NAPL) and its implications for screen design are discussed In 4.5.4. In the presence of free-phase organics, the casing should withstand corrosion by NAPL.
The presence of free-phase contaminants also has implications for health and safety, and for contaminant migration during drilling. The contaminants likely to be encountered affect the choice of material (suitability in terms of sorption, contaminant release, risk of corrosion), the drilling method, and the health and safety assessment. Contaminated spoil and groundwater require special handling, storage, and disposal.ISO 5667-22-2010 pdf free download.
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