You've been tasked with siting a new well in a confined aquifer that already has several operating wells. Drilling logs indicate that the aquifer is primarily sand and gravel with ar average thickness of approximately 200 ft. You have specific capacity data from several drilling logs in the area (table 1), as well as data from a 48-hour single well pump test that was previously performed at well AG-1 several years ago (table 2). At the end of the single well test, simultaneous drawdown measurements were taken in several monitoring wells surrounding the pumping well (table 3). Estimate the transmissivity and storativity of the aquifer, along with a realistic range of uncertainty around those numbers. Table 1: Specific capacity data for nearby wells WELL BOREHOLE PUMPING STABILIZED DIAMETER DRAWDOWN 24 inches 16 inches 8 inches MW-1 AG-1 HH-1 Table 2: Single-well pump test on AG-1 at 500 gpm Time (min) Drawdown (ft) 12.4 13.2 13.7 14.0 14.3 14.5 14.7 14.8 15.0 15.1 15.9 16.4 16.7 17.0 17.2 18.0 18.5 18.8 19.1 19.3 19.8 20.1 20.9 21.4 21.8 1 2 3 4 5 6 7 8 9 10 20 30 40 50 60 120 180 240 300 360 540 720 1440 2160 2880 RATE 1200 gpm 800 gpm 25 gpm 48 ft 33 ft 1 ft Table 3: Synoptic data after 24 hours of pumping AG-1 Distance from pumping well (ft) TIME OF OBSERVATION 1 day 18 hours 3 hours 68 110 232 298 321 Observed Drawdown (ft) 10.4 9.0 7.2 6.9 6.2
You've been tasked with siting a new well in a confined aquifer that already has several operating wells. Drilling logs indicate that the aquifer is primarily sand and gravel with ar average thickness of approximately 200 ft. You have specific capacity data from several drilling logs in the area (table 1), as well as data from a 48-hour single well pump test that was previously performed at well AG-1 several years ago (table 2). At the end of the single well test, simultaneous drawdown measurements were taken in several monitoring wells surrounding the pumping well (table 3). Estimate the transmissivity and storativity of the aquifer, along with a realistic range of uncertainty around those numbers. Table 1: Specific capacity data for nearby wells WELL BOREHOLE PUMPING STABILIZED DIAMETER DRAWDOWN 24 inches 16 inches 8 inches MW-1 AG-1 HH-1 Table 2: Single-well pump test on AG-1 at 500 gpm Time (min) Drawdown (ft) 12.4 13.2 13.7 14.0 14.3 14.5 14.7 14.8 15.0 15.1 15.9 16.4 16.7 17.0 17.2 18.0 18.5 18.8 19.1 19.3 19.8 20.1 20.9 21.4 21.8 1 2 3 4 5 6 7 8 9 10 20 30 40 50 60 120 180 240 300 360 540 720 1440 2160 2880 RATE 1200 gpm 800 gpm 25 gpm 48 ft 33 ft 1 ft Table 3: Synoptic data after 24 hours of pumping AG-1 Distance from pumping well (ft) TIME OF OBSERVATION 1 day 18 hours 3 hours 68 110 232 298 321 Observed Drawdown (ft) 10.4 9.0 7.2 6.9 6.2
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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Transcribed Image Text:# Analyzing Well Data for Aquifer Management
You've been tasked with siting a new well in a confined aquifer that already has several operating wells. Drilling logs indicate that the aquifer is primarily sand and gravel with an average thickness of approximately 200 ft. You have specific capacity data from several drilling logs in the area (Table 1), as well as data from a 48-hour single well pump test that was previously performed at well AG-1 several years ago (Table 2). At the end of the single well test, simultaneous drawdown measurements were taken in several monitoring wells surrounding the pumping well (Table 3). Estimate the transmissivity and storativity of the aquifer, along with a realistic range of uncertainty around those numbers.
## Table 1: Specific Capacity Data for Nearby Wells
| WELL | BOREHOLE DIAMETER | PUMPING RATE | STABILIZED DRAWDOWN | TIME OF OBSERVATION |
|------|-------------------|--------------|---------------------|---------------------|
| MW-1 | 24 inches | 1200 gpm | 48 ft | 1 day |
| AG-1 | 16 inches | 800 gpm | 33 ft | 18 hours |
| HH-1 | 8 inches | 25 gpm | 1 ft | 3 hours |
## Table 2: Single-Well Pump Test on AG-1 at 500 gpm
| Time (min) | Drawdown (ft) |
|------------|---------------|
| 1 | 12.4 |
| 2 | 13.2 |
| 3 | 13.7 |
| 4 | 14.0 |
| 5 | 14.3 |
| 6 | 14.5 |
| 7 | 14.7 |
| 8 | 14.8 |
| 9 | 15.0 |
| 10 | 15.1 |
| 20 | 15.9 |
| 30 | 16.4 |
| 40 | 16.7 |
| 50 | 17.0 |
| 60 | 17.2 |
| 120 | 18.0
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