1. Water Well Design August 6, 2015 AL/MS AWWA
Ralph Hayes, P.E., BCEE
Engineering Director
MSDH, Bureau of Public Water Supply

2. Water Well Design -Why drill a water well? -How to get started.
-Where to drill a water well
-Steps in drilling a water well

3. Why Drill a Water Well
--usually when someone decides they need more water, or a more dependable water supply.
Longer Run Times- if consistent run times of 12 hrs +
Average Well Life- if average well service life is high, expect failures to occur more frequently
Back up Supply- if lose water service, need supply to bring plant or factory down

4. How to Get Started MUST DETERMINE
-- How much water needed (maybe need 2 wells)
-- Where is water needed (have it close to demand point)
- What quality? ( potable or process water)

5. How to Get Started First Round Considerations
-Once preliminary considerations are resolved, the investigation begins. The question now is, can you get the amount of water needed, delivered to where it is needed, in the quality needed.

6. How to Get Started
Resources to help determine the likely availability of water………..
DEQ, with location can get other wells in area
Well Driller, can get specific data of existing wells in area
MSDH, Bureau of Public Water Supply
USGS, or USGS Retired

7. How likely is water available
Take collected data, interpolate between wells to determine “expected” well depth, static water level, well yield.

8. Sample Example
For this discussion, we will estimate the following parameters-
--500’ to bottom of aquifer
--aquifer thickness is 60 feet
--pump rate needs to be 500 gpm

9. Test Hole
A Test Hole is a pilot hole drilled to expected Total Depth (TD) of the well, expecting to penetrate the aquifer completely. Sand samples are collected and an e-log is run on the Test Hole.
Sand Sample when analyzed, help determine the slot size of the well screen.
E-log determines where the top and bottom of the screen begin and end.

10. Electric Log

11. E-log, marked up

12. Test Well
A Test Well is a small diameter (4” -6”) well and screen, set in the “sands” seen from the e-log and a pump capable of pumping gpm.
The Test Well is set and developed and pumped until a representative sample is collected and tested.

13. Sample Test Well Results1

14. Test Well
Pro- get good idea of water quality before making permanent well.
Con feet of screen might not cover entire aquifer and water quality might be different in areas not screened
Com- pump rate of gpm usually significantly less that permanent pump rate,
Chance of 500 gpm pump producing turbidity

15. Permanent Well
Ream Test Hole and set & cement casing to top of water bearing sands.
Under ream sand zone (below casing) and set screen/lap, gravel

16. Casing
Have to determine if you want Foreign or Domestic Pipe, (foreign typically cheaper).
Have to determine if you want Prime (w/mill certs) or Structural grade pipe, (Prime is more expensive).
Determine is welded or threaded joints, welded is the standard.
Specify pipe must have factory bevel, not torch cut

17. Setting Casing 1

18. Welding Casing 1

19. 2-Piece Well

20. We Drawing 1

21. Well Screen
Typical well screen is referred to “Stainless Steel Wire Wrapped Rod Base Screen”
Typical in 20’ or 10’ scetions
Slot size determined from info obtained in TH

22. Stainless Steel WW Rod Base1

23. Drill Rigs 1

24. Drill Rig

25. Mud Pits, Mud Pump 1

26. Drill Rig

27. Finished Water Wells
Various ages

29. Well w/ Generator 1

30. Tight Location 1

31. Questions ?
Ralph Hayes