Handbook of Civil Engineering Calculations

Time, doys

Sl Values

ft m gpm Us

2 0.6 450 28.4

4 1.2

6 1.8

8 2.4 8.2ft 2.5m

10 3.0

FIGURE 7. Drawdown-recovery curves for a gravity well. (Babbitt, Doland,

and Cleasby.)

TABLE 1. Coordinates for the Drawdown-Recovery Curve of a Gravity Well

(1) I (2) I (3) I (4) I (5) I (6) I (7) I (8) I (9) I (10)

Time Time Time

after 2.95 x after 2.95 x after 2.95 x Col 6

pump Iog 10 pump Iog 10 pump Iog 10 minus

starts, re _ , re _ starts, re _ , re _ , stops, re _ , re _ , col 9 =

hr ^x~r° ^" ° h r (^7) x~r' Vw~^ h r (^7) x~r' ~w~^ dr
0.25 5 4 5.1 0 5 4 78 4 8. 5 6 26 3 7. 2 1. 3
0.50 7 6 5.4 5 6 6 87 2 8. 7 1 8 45 5 7. 9 0. 8
1.00 10 7 6. 0 7 8 95 0 8. 8 3 0 58 7 8. 2 0. 6
6 26 3 7. 2 9 0 1,02 0 8. 9 4 2 69 4 8. 4 0. 5
24 52 6 8. 0 10 2 1,08 5 8. 9 5 4 78 4 8. 5 0. 4
48 74 5 8. 5
Conditions: rw = 1.0 ft; he = 50 ft. When Q = 1 ft^3 /s and rx = 1.0 ft. (he - Hx) = 8.0 ft. When Q = 1
ft^3 /s and rx - 60 ft, (he - hx) = 3.0 ft. Specific yield = 0.25; &, as determined in step 1 of example, =
0.0027; and he - (he^2 - 1.79g/*)°-^5 = 6.8.
Pumping
stopped-
Drowdown
curve
Recovery
curve
Residual drawdown
Static water level
Pumping
begun
450gpm
Drawdown
to
water,
ft
Drawdown
8.0 ft
Recovery
8.2 ft