1. 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.

2. Head loss through screen Head loss near screen Head loss in aquifer How to reduce head loss?

3. Why is it important? 1Most sensitive area, where flow converges and is the fastest 1Where we still have means to modify the aquifer

4. Ultimate Goals 1Make the pores as big as possible so water is free to flow. Results: 1more flow 1lower costs of operation (reduced drawdown = less energy to lift the water = reduced hydro bill)

5. Other goals 1Removes fines 1Water quality 1Minimize abrasion on equipment (extend life of pumping and piping equipment) 1Creates zone of Autofiltration

7. Development Methods 1Overpumping 1Surging 1Air Lift 1Jetting 1Explosive (rock aquifer)

8. Overpumping Increased gradient Drawdown during operation Drawdown during development

9. Surging

10. Air lift

11. Jetting

13. Overpumping Pros Cons 1Simple 1No special equiment  No reverse flow  No agitation of soil particles  Low energy impact  Low efficiency  Requires removal of fines

14. Autofiltration

15. Surging Pros Cons 1Simple technology 1Low Cost  Flow bypass  Low level of impact  Relatively Low efficiency  Requires removal of fines

16. Air Lift Pros Cons 1Efficient Method 1Combine removal of fines 1Easy to adjust/control energy level  Requires “sophisticated” Equipment (e.g. compressor)  Requires good understanding of aquifer conditions  Does not target specific screened zones

17. Jetting Pros Cons 1Most Efficient Method 1Easy to adjust/control energy level 1Easy to target specific screened zone 1Enhance movement of particles “deep” into the aquifer. 1Screens designed for jetting (V-wire)  Requires “sophisticated” Equipment (e.g. compressor)  Requires good understanding of aquifer conditions  Requires removal of fines

19. 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