SUBTITLE F: PUBLIC WATER SUPPLIES
CHAPTER II: ENVIRONMENTAL PROTECTION AGENCY
PART 671 MAXIMUM SETBACK ZONE FOR COMMUNITY WATER SUPPLY WELLS
SECTION 671.APPENDIX B THEIS EQUATION USING AVAILABLE DATA
Section 671.APPENDIX B Theis Equation Using Available Data
If pump test data is available for an unconfined/confined unconsolidated or non-fractured bedrock aquifer the lateral radius of influence can be calculated as follows:
|
r |
= |
the square root of |
uTt |
|
2693S |
Where:
|
r |
= |
radius of influence (feet) |
|
t |
= |
time well is pumped under normal operational conditions (minutes) |
|
S |
= |
aquifer storativity or specific yield (dimensionless) |
|
T |
= |
transmissivity (gallons per day per foot) |
|
u |
= |
= is a dimensionless parameter related to the well function |
|
W(u) |
= |
T(ho - h) |
|
114.6Q |
Where:
|
W(u) |
= |
well function, the well function is calculated and u is obtained from Table A. |
|
ho - h |
= |
drawdown in the piezometer or observation well (feet) |
|
Q |
= |
production well discharge rate under normal operational conditions (gallons per minute) |