Former bus depot, Mill Lane
A depot with fuel tanks becomes 46 homes with gardens (sample project).
Borehole BH01, former bus depot, Mill Lane (sample)
Drilled on 14 May to 8.00 m with a cable percussion rig. Ground level 42.10 m. Logged by R. Okoye (sample).
Depth (m)
Layer as logged
Samples and tests
What it means for the site
0.00–0.30 m
Topsoil
Dark brown sandy topsoil with grass roots.
S1 at 0.10 m: metals and an asbestos screen
Fit to reuse in the new gardens if the lab results stay below the screening levels (sample).
0.30–1.80 m
Made ground
Grey-black ash, brick, clinker and broken concrete. Diesel odour from 0.90 m.
S2 at 0.90 m: hydrocarbons, PAHs and metals. Gas reading 85 ppm
Hydrocarbons above the level for homes with gardens. Dig out or cover with clean soil before building (sample).
1.80–4.50 m
Clay
Firm brown silty clay, mottled grey. Water struck at 3.20 m , rose to 2.60 m in 20 minutes.
S3 at 2.50 m: no odour, kept for testing
A tight layer that slows anything in the made ground on its way down to the gravel.
4.50–7.20 m
Sand and gravel
Wet orange-brown sand with flint gravel.
Monitoring well screened from 4.50 to 7.00 m; water sampled every month
The groundwater that feeds the brook downstream. We check that it stays clean (sample).
7.20–8.00 m
Mudstone
Weathered grey mudstone. End of hole at 8.00 m.
None
Bedrock, nothing to report. The hole above the well was sealed with bentonite.
Topsoil Made ground Clay Sand and gravel Mudstone ▽Water struck ▼Water level after 20 minutes
Depths in metres below ground level. The core is drawn to scale; the rows say what the drill found and what it means for the new homes planned on the site (sample log).
What happened next
Risk assessment
Hydrocarbons in the made ground were above the levels for gardens; the clay and groundwater were clean (sample).
Strategy
Dig out made ground under gardens; clean cover of 600 mm; membrane under two plots near the old tanks.
Verification
Cover depths checked in 46 hand pits, one per garden (sample).
Condition
Discharged in March, eleven months after the first desk study (sample).
Send us the site address
We check the old maps and the planning record before we reply, so the quote fits the site. Most quotes go out within two working days (sample).