Field notes
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Critical speed and reed frequency: why your drive has a skip band
A vertical turbine on a drive has four frequencies that matter. Where a skip band comes from, what margin your evidence earns, and the…
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Private wells and municipal wells: what changes, and what does not
A domestic well and a 1,000 gpm municipal well share the same physics but not the same obligations. What private well owners and small…
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What a water district should get from every drilling, pump and rehabilitation contractor
The deliverables a water district should require from drilling, pump and rehabilitation contractors, and the manufacturers’ data that belongs in every well record.
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Casing, screen and gravel pack: how a water well’s construction decides how long it lives
Casing, screen and slot size, filter pack, seal depth and development set a water well’s yield, sanding and plugging rate for forty years. What…
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SGMA annual reporting: what a GSA actually needs from a district’s well records
Each spring GSAs report extraction, elevation and storage change to DWR from member districts’ wells. What the SGMA annual report needs and where the…
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How to read a pump curve: BEP, operating range, VFD speed and the affinity laws
How to read a well pump curve: head, efficiency and horsepower curves, BEP and the preferred operating region, VFD speed in Hz and rpm,…
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When to rehabilitate a water well — and what waiting costs
Well rehabilitation timing is an economics problem: when a well has plugged far enough, which method suits which fouling, and what waiting costs.
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How to read a pump efficiency test: wire-to-water efficiency, kWh per acre-foot and what the numbers cost
A pump efficiency test gives three numbers that matter: wire-to-water efficiency, kWh per acre-foot and the dollars recoverable. The arithmetic and the benchmarks.
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Specific capacity: the first number to watch on any water well
Specific capacity (gpm per foot of drawdown) is the earliest honest sign a water well is plugging. How to measure it, compare it fairly…