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Trench & Flowable Fill Calculator

Calculate the net volume of concrete, slurry, or flowable fill (Controlled Low-Strength Material / CLSM) required to backfill utility trenches, sewer line cuts, and conduit encasements with automatic buried pipe displacement deduction.

Interactive Trench Calculator

ENGINEERING SCHEMATIC
Excavated Continuous Trench Pour
Volume (V) = Area × Depth 1 Cubic Yard = 27 Cubic Feet
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Pro Contractor Recommendation: Trench pours conform to hand-dug or backhoe trenches. Add 15% waste contingency due to uneven trench sidewall blowouts and irregularities.
Trench Dimensions
Buried Pipe / Conduit Displacement (Optional)
%
Net Fill Concrete / Flowable Fill Required
20.28 cu yds
(547.5 cu ft / 15.50 m³)
Mixer Truck Loads
3 trucks
Based on 9 cu yd standard ready-mix drums
Pipe Volume Deducted
2.91 cu yds
Displaced by conduit / utility line
Pre-Mixed Bags (80 lb)
913 bags
or 1217 bags (60 lb)

What is Flowable Fill (CLSM)?

Flowable fill (Controlled Low-Strength Material or slurry) is a self-leveling cementitious backfill material used in place of compacted soil or stone in utility trenches:

  • Zero Compaction Required: Flows around utility pipes and conduits effortlessly without mechanical vibratory tamping, eliminating trench settlement depressions under roads.
  • Excavatable Strength: Engineered with low compressive strength (50 to 200 PSI) so that future utility repair crews can easily re-excavate with standard backhoes.
  • Rapid Placement: Discharged directly from ready-mix trucks into trenches, allowing pavement patching to proceed within hours.