Stump Grinding Volume, Chip Yield, and Backfill

A stump has a root flare and buttress roots that spread well beyond the trunk, and the grinder has to take them -- so a two foot stump is a three foot grind, and because volume goes as the SQUARE of the diameter that is well over twice the material at the same depth. The multiple is reported here for exactly that reason: it is the number that separates a bid from a loss. DEPTH IS SET BY THE OBJECTIVE rather than by habit. Six to eight inches is enough to put turf over; replanting in the same spot needs considerably more, and a stump ground to turf depth and then planted into is a tree planted in a bed of chips. CHIPS SWELL, and then they settle. Ground material occupies one and a half to two times its in-place volume, so the hole cannot hold what came out of it and the excess is hauled or spread -- and the part that goes back settles substantially as it decomposes, which is why a hole backfilled level is a depression a season later. The topping volume is reported for that reason: it is a second visit that belongs in the price or in the conversation. AND CHIPS ARE NOT SOIL. They are high in carbon, and the microbes decomposing them take nitrogen out of the surrounding soil to do it, so a new tree planted into a chip-filled hole competes for nitrogen with the decomposition of the last one. Replanting in the same location means removing the chips and replacing them with soil, which is a different job from grinding and should be priced as one. A volume estimate from a geometry the reader measures. It does not locate utilities, which is the thing that matters most before a grinder starts and which requires a locate; it does not address the surface protection, the debris containment, or the damage a grinder does to adjacent turf, roots, and hardscape. It does not assess whether the roots beyond the grind will be an issue -- large lateral roots of a removed tree decay and can leave voids and settlement well outside the ground area -- or address stump removal by excavation, which is a different operation with different quantities. The utility locate, the site conditions, and the operator's own judgment govern.

in-place volume = pi/4 x the GROUND diameter squared x the depth, where the ground diameter includes the root flare and is wider than the visible stump; chips = that times the swell factor; the hole holds its own in-place volume and the rest is excess; and the backfill settles by an entered fraction, which is the topping needed later.

The stump grinding volume relations by name, with chips swelling to 1.5 to 2 times their in-place volume. Depth is set by the objective: 6 to 8 in for turf, deeper for replanting. Chips are high in carbon and tie up nitrogen, so replanting in the same hole means replacing them with soil. IT DOES NOT LOCATE UTILITIES, which is what matters most before a grinder starts. The utility locate, the site conditions, and the operator's judgment govern.

Two cylinder volumes and a swell factor; no production data is reproduced.

Estimate. AHJ and licensed professional govern.

Field names used by the API: stump_diameter_in, grind_diameter_in, grind_depth_in, swell_factor, settlement_fraction, stump_only_volume_ft3, in_place_volume_ft3, flare_multiple, chip_volume_ft3, backfill_volume_ft3, excess_volume_ft3, topping_volume_ft3

• The ground diameter is entered it includes the flare and is wider than the visible stumpthe operator's judgment
• No utility locate which is the thing that matters most before a grinder startsthe utility locate
• Lateral roots beyond the grind are not addressed they decay and can leave voids well outside the ground areathe site conditions