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Why Developing?. Restore aquifer, following damage due to drilling Reduce head loss by increasing permeability Increase well efficiency Reduce drawdown and cost of extracting groundwater Restore/Rehabilitate well due to gradual clogging and biofouling. How to reduce head loss?.
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Why Developing? • Restore aquifer, following damage due to drilling • Reduce head loss by increasing permeability • Increase well efficiency • Reduce drawdown and cost of extracting groundwater • Restore/Rehabilitate well due to gradual clogging and biofouling.
How to reduce head loss? Head loss in aquifer Head loss near screen Head loss through screen
Why is it important? • Most sensitive area, where flow converges and is the fastest • Where we still have means to modify the aquifer
Ultimate Goals • Make the pores as big as possible so water is free to flow. Results: • more flow • lower costs of operation (reduced drawdown = less energy to lift the water = reduced hydro bill)
Other goals • Removes fines • Water quality • Minimize abrasion on equipment (extend life of pumping and piping equipment) • Creates zone of Autofiltration
Development Methods • Overpumping • Surging • Air Lift • Jetting • Explosive (rock aquifer)
Overpumping Drawdown during operation Increased gradient Drawdown during development
Simple No special equiment No reverse flow No agitation of soil particles Low energy impact Low efficiency Requires removal of fines Overpumping Pros Cons
Simple technology Low Cost Flow bypass Low level of impact Relatively Low efficiency Requires removal of fines Surging Pros Cons
Efficient Method Combine removal of fines Easy to adjust/control energy level Requires “sophisticated” Equipment (e.g. compressor) Requires good understanding of aquifer conditions Does not target specific screened zones Air Lift Pros Cons
Most Efficient Method Easy to adjust/control energy level Easy to target specific screened zone Enhance movement of particles “deep” into the aquifer. Screens designed for jetting (V-wire) Requires “sophisticated” Equipment (e.g. compressor) Requires good understanding of aquifer conditions Requires removal of fines Jetting Pros Cons
Wrap Up • Development is very important • Immmediately following well completion • As part of the maintenance of the well • Development is very complex and need to be designed properly to be efficient