Serving the Cowichan Valley
Excavation and site work around Shawnigan Lake
Shallow bedrock, a drinking-water lake, and a community with good reason to ask where fill came from.
Bedrock outcrops east and west of Shawnigan Lake, and the till above the rock is typically under 5 metres thick or absent altogether. Several thousand residents in this Cowichan Valley Regional District electoral area draw household water from the lake, so Duncan Excavating treats fill provenance and sediment control as part of the scope.
Shawnigan Lake asks two questions of any excavation job that most places do not. What is actually under the topsoil, given how close bedrock sits here — and where is the material coming from, or going to.
Rock is the main variable. Bedrock outcrops are mapped on both sides of the lake and the confining layer above it is typically about 5 metres thick and sometimes absent, so a dig that would be routine on the valley floor can need a breaker instead of a bucket.
Rock, and how close to the surface it is
Provincial aquifer mapping records bedrock outcrops, or bedrock under only a veneer of surficial material, to the east and west of the lake. The till and marine deposits above it can reach 30 metres in places on the east side but are typically less than 5 metres thick or inferred to be absent. Water-bearing fractures in the bedrock sit at a median of around 80 metres. For excavation that means the answer to whether a footing or a trench hits rock is genuinely site-specific, and worth establishing before a machine is booked rather than after.
Why fill provenance matters more here
The regional district's plan for this area notes that several thousand residents rely on Shawnigan Lake for their household water. The area also has direct experience of the question: a contaminated-soil treatment and landfill operation was permitted at a former quarry on Stebbings Road in August 2013, the Province suspended the permit in January 2017 and cancelled it the following month, a final closure plan was approved in June 2019, closure construction was completed in the autumn of 2020, and the site remains under post-closure environmental monitoring. Nothing about that history is unusual to raise on a quote here. Knowing where imported fill comes from, and where excavated material is going, is a reasonable thing for a property owner to ask.
Anyone with a Shawnigan Lake project is welcome to request a quote, and the rock question gets answered by looking at the site.
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.
- Perimeter Drains and DitchingPerimeter drains, ditching and service trenches across the Cowichan Valley, where groundwater on the valley floor sits at a median of 2.4 metres.
Nearby service areas
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Duncan Excavating quotes excavation across the Cowichan Valley after a site visit.