Land & groundwater

The commonest expensive mistake on brownfield land is treating a laboratory exceedance as a problem in itself. Contaminated land in England is assessed as a source–pathway–receptor linkage: lead at 900 mg/kg under a slab that is staying put, with no exposure pathway, is not a risk requiring remediation, and we have argued that successfully with three local authorities in the last two years. Digging it out anyway costs money and lorry movements and achieves nothing.

Where a linkage does exist we would rather design around it than excavate it. A capping layer, a gas membrane properly detailed at the service penetrations, or a change to the garden layout will each usually cost less than a dig-and-dump, and dig-and-dump has an embodied carbon cost that nobody used to count and planning authorities increasingly do.

Groundwater work is where the timescales bite. An Environment Agency permit or a hydrogeological risk assessment for a discharge can take three months to determine and longer if the submission is incomplete. We handle the pre-application discussion, and we will tell you at the outset if we think the abstraction or discharge you are planning is unlikely to be permitted.