Precast Concrete Catchpit / Silt Trap Quantity Calculator
Precast concrete catchpit with integral silt sump below outlet invert, to BS 5911-3:2014, with BS EN 124 frame and cover. Computes excavation, monolithic base, chamber rings, cover slab, granular surround, and silt storage capacity.
Slug · catchpit · v1.0
Paid tier
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Precast Concrete Catchpit / Silt Trap — a worked example, measured four ways
The same assembly at default dimensions, rendered as a Bill of Quantities under each measurement standard. Switch the standard to see how the bill changes. Change the inputs in the calculator to compute your own.
CESMM4 · 13 items · units sum, nr, m³, m²
| Code | Description | Unit | Quantity |
|---|---|---|---|
| A.4.1 | Provisional sum (Prime Cost): Frame & cover, D400 loading, 600mm clear opening, with 150mm adjustment rings | sum | 1 |
| A.4.1.fix | Fixing only: Frame & cover, D400 loading, 600mm clear opening, with 150mm adjustment rings | nr | 1 |
| E.4.3.5 | Excavation for foundations, maximum depth 2-5m | m³ | 68.85 |
| E.5.3 | Disposal of excavated material off-site | m³ | 4.81 |
| E.6.3.2 | Filling, imported selected granular material, Class 6N to SHW | m³ | 0.4 |
| E.6.2.1 | Filling, excavated material | m³ | 64.04 |
| E.6.5.1 | Filling, imported sub-base, Class 6N per SHW 601 Table 6/1 row 6N | m³ | 0.38 |
| L.5.2 | Granular surround to pipe, 20mm single-size aggregate | m³ | 0.86 |
| K.1.6.2 | Precast concrete catchpit / silt trap to BS 5911-3, 1200mm internal diameter, depth to outlet invert 2.5m, with integral silt sump 750mm below invert (silt capacity ~848L) | nr | 1 |
| K.1.3.1 | Precast concrete chamber ring to BS 5911-3, 1200mm internal diameter, 500mm depth | nr | 4 |
| K.1.5.1 | Precast concrete cover slab to BS 5911-3, 1500mm outer diameter, 600mm clear opening | nr | 1 |
| K.8.1 | Galvanised step irons cast into precast rings, 300mm centres | nr | 7 |
| E.7.2 | Geotextile filter, 200 g/m², including laps | m² | 6.84 |
Procurement take-off: the total quantity to order of each material, from the same compute. Supplier-neutral, so you buy anywhere.
- Disposal4.81 m³
- Excavation Foundation68.85 m³
- Fill General64.04 m³
- Fill Selected0.4 m³
- Fill Sub Base0.38 m³
- Geotextile Filter6.84 m²
- Manhole14 nr
- Manhole1 sum
- Pipe Surround0.86 m³
Illustrative example at default dimensions · engine ref 7f9967 · not a tendered quantity