Well Drawdown and Specific Capacity
Drawdown, specific capacity (GPM per ft), and recommended pump-setting depth, with a marginal-well flag below 0.5 GPM/ft. Per AWWA A100 and USGS OFR 02-197.
Formula and source
Drawdown (ft) = pumping water level - static water level. Specific capacity (GPM/ft) = discharge / drawdown. Recommended pump setting (ft) = pumping level + offset (default 20 ft below the pumping level).
AWWA A100 (Water Wells) standard; USGS well-testing methods (USGS Open-File Report 02-197).
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