How Bilby works
Rock excavation and blasting costs
Rock volume and a mobilisation package
Rock cost comes from estimated excavation below the inferred rock surface. Native groundworks price the rock quantity and, when the high scenario exceeds 5 m³, a blasting setup package. The threshold is a model rule, not a legal limit or a contractor’s minimum order.
What is and is not included
Native rock treatment includes the volume rate plus blasting mobilisation, neighbour inspection and vibration monitoring when triggered. Disposal and reuse are reconciled in mass handling. Terrain rock is incremental to preparation rock. The combined method uses one shared blasting package rather than charging both complete setups. The estimate does not select a permitted blasting design or guarantee that blasting is the appropriate treatment.
Estimated exposure
Depth uncertainty is important: shallow bedrock can increase rock excavation even when the visible ground is level.
| Input | Unit | Where from? |
|---|---|---|
| Required treatment depth | m | Foundation and soil profile |
| Depth to bedrock | m | Mapped/modelled estimate and range |
| Affected area or terrain cells | m² | House and selected grading |
| Rock to remove | m³ | Overlap of excavation and rock |
| Neighbour and access conditions | scope | Broad allowance; site review required |
Native and reference paths
Native rock treatment rates are SEK 350 / 475 / 600 per m³. Triggered fixed costs total 18,000 / 30,000 / 53,000: mobilisation 10,000 / 15,000 / 25,000, inspection 5,000 / 10,000 / 20,000 and monitoring 3,000 / 5,000 / 8,000. The national standalone reference instead uses fixed 25,000 / 50,000 / 100,000 plus volume × 1,000 / 1,800 / 3,000. It is a different specification, not an extra uplift on an existing native amount.
Illustrative 20 m³ treatment
With 20 m³ in all scenarios, native rock plus its triggered setup package is SEK 25,000 / 39,500 / 65,000 before whole-groundwork rounding. Expected is 20 × 475 + 30,000. The standalone reference for the same stated volume gives SEK 45,000 / 86,000 / 160,000. Disposal remains separately owned in the applicable mass-handling scope; do not add both methods.
What needs investigation
Changing pad depth, placement, foundation or depth evidence changes exposure. A nearby borehole does not prove the rock level beneath your house. Missing depth is not proof of no rock; read provisional warnings. Near buildings or sensitive structures, inspections and monitoring must be scoped with the contractor rather than inferred from these fixed allowances.
Method and evidence
Reviewed 18 October 2026: native groundworks/terrain 2026 version 2 and reference catalogue researched 16 September 2026. SGU provides geological context, not blasting rates SGU. Both sets of figures are Bilby planning assumptions, not verified blasting quotations.
The review date covers this explanation and its implemented method. Price and data dates are stated separately in the article.