Serving the Cowichan Valley
Excavation in Mill Bay and Cobble Hill
Two electoral areas, two very different depths to rock, and a map that will not tell you which one a property sits on.
Near-surface bedrock less than 1 metre down is mapped across most of the Malahat Ridge area, while the same provincial study found unconsolidated deposits reaching 60 metres thick in a buried bedrock valley. Duncan Excavating prices Mill Bay and Cobble Hill work from the site rather than from the map.
This page covers two communities that share a problem. Bedrock is close to the surface across most of the area, except where it is not — and the difference is dozens of metres, over short distances, with no reliable way to tell from the road.
Depth to rock is the whole question. Breaking rock uses a hydraulic breaker on a larger machine rather than a bucket, which is a different rate and a different schedule, so a site visit here is worth more than anywhere else in the service area.
How close the rock actually is
Provincial mapping of the Malahat Ridge aquifer states that near-surface bedrock, less than 1 metre below surface, has been mapped within the majority of the aquifer area. The bedrock is fractured crystalline rock — volcanics of the Bonanza Group and intrusives of the Island Plutonic Suite — and the confining layer above it ranges from about 1 to 24 metres but is typically around 5 metres, and may be absent. A separate detailed study of the wider Shawnigan and Mill Bay area found unconsolidated deposits up to 60 metres thick and a bedrock surface described as highly irregular. Both statements are true of this area at the same time, which is precisely why a quote here follows a site visit.
Two electoral areas, two sets of farmland rules
Mill Bay sits in Electoral Area A and Cobble Hill in Electoral Area C, and the Agricultural Land Reserve share differs sharply between them — about 9 per cent of Area A against about 43 per cent of Area C. That matters for anything involving fill or soil removal, because a Notice of Intent to the Agricultural Land Commission applies on reserve land and does not on the rest. Both areas fall under the same Cowichan Valley Regional District building bylaw, which requires a permit to construct or structurally repair a retaining wall and requires professional engineer certification for fill slopes steeper than 1:2.
Anyone planning groundwork at Mill Bay or Cobble Hill is welcome to request a quote, and what is under the topsoil gets checked before a number is given.
Excavation services
- Footings and FoundationsExcavation and backfill for footings and foundation walls across the Cowichan Valley, cut to surveyor's levels and planned around a winter water table.
- Driveways and CulvertsRural driveways, turnarounds and culvert crossings across the Cowichan Valley, including the access permits that apply on provincial and municipal roads.
Nearby service areas
Ready for a quote on excavation in Duncan?
Duncan Excavating quotes excavation across the Cowichan Valley after a site visit.