Drilling fluid & borehole volume calculator
For HDD: borehole volume in gallons, spoil in cubic yards, the annular space around your product pipe, and a planning estimate for how much drilling fluid to have on hand.
The fluid number is a planning estimate, not a mix spec — how much you actually pump swings hard with soil: reactive clays and open sand or gravel drink far more than the borehole volume. Size your tank and bentonite off the high end and carry extra.
Common questions
It is a cylinder: volume equals pi times the radius squared times the length. In field units, gallons ≈ 0.0408 × diameter (inches) squared × length (feet). A 300 foot bore reamed to 6 inches holds about 441 gallons, or roughly 1.47 gallons per foot.
Plan on more than the hole itself — commonly 2 to 3 times the borehole volume in stable clay or loam, and considerably more in sand, gravel, or fractured ground that keeps taking fluid. Size your tank and bentonite off the high end, since running out mid-pull is how a bore gets stuck.
The space left around your product pipe once it is in the hole — the borehole volume minus the volume the pipe takes up. It is the number you use when you are grouting or backfilling the annulus, or estimating fluid returns during pullback.
About one borehole volume of cuttings, since that is the ground you removed. That 300 foot, 6 inch bore is roughly 2.2 cubic yards of spoil — before it swells and mixes with fluid, which is why the slurry you actually manage is a good bit more.
A common rule is a final hole about 1.5 times the product outside diameter, so a 2 inch conduit is reamed to around 3 inches, and a larger bundle proportionally bigger. Bigger holes pull easier but use more fluid and make more spoil, so it is a trade-off you set per soil and pullback length.
TrackOver's FiberOps tracks daily footage, 811 mark-outs, permits, splices, and a bore log with the depth-of-cover an inspector asks for — plus crew-readable route maps built from your KMZ designs.