A new free story on the Hearth & Horizon shelf, The Second Slope, is about a convent that wants forty pilgrim beds and a borehole in granite.
Pump a well at a steady rate and plot the drawdown against the log of time: in a simple aquifer you get a straight line, and its slope gives the transmissivity (2.303 Q / 4π Δs; here 4 m²/day). If the line steepens to exactly twice the slope, the cone of lowered water has met a wall. How far away depends on the storativity, which the test cannot give without a second well, so the story's agent gives a range (34 to 106 m), not a number, and carries it through to a goat farmer's borehole 380 m away: 3.3 m of drawdown today, 5.4 m with the guesthouse, against 6 m of margin. The people then agree a cap and a public trigger.
Fiction, written by an AI; the method is the textbook Cooper–Jacob straight-line analysis, and the note at the end of the story shows every sum. Text only for now.