Sign off from difficult council achieved

9th April 2024

Geoenvironmental • Geotechnical • Specialist Services

What would normally be a relatively straight forward investigation, to support a project to renovate a Victorian terraced house and build a new extension to the rear, required Ground & Water to go several extra miles for its client. Overcoming inevitable environmental health hurdles placed in its way by a notoriously difficult council planning department, required diligence, patience, professionalism and persistence. This thankfully won the day for our client

Our Client

Our client was a London-based property developer.


The project comprised the renovation of an existing dwelling including small extension to the rear.

A Desk-based review indicated the site to be underlain by superficial Langley Silt Member over superficial Kempton Park Gravel Member over bedrock deposits of the London Clay Formation.

The study also revealed a primary source of contamination could impact the site from a former electrical equipment and glass manufacturer – later used as a depot/yard – which was adjacent to the property.

As a minimum, a contamination risk assessment would be required, but historically the council might insist on a full Site Investigation.


Our Challenge

The site was situated in a borough with a council well-known for creating difficulties when trying to pass through contamination risk assessments. The council regularly asks for over and above the norm, so our main challenge was to ensure we had a strong evidenced based plan and strategy to deal with whatever hurdles were placed in this project’s way; and to keep the costs at a realistic level for the client.

The Ground & Water Approach

As part of the desk study, publicly available information was searched and fortunately a full desk study, site investigation, remediation strategy and validation report for the neighbouring site that was the primary source of concern for contamination, was found.

A gap analysis on this information was undertaken, which showed the site had been suitably remediated, allowing for the risk from this source to be reduced. In conjunction with this the following was observed:

  • The presence of hardstanding and the building across the majority of the site will reduce infiltration and leachate production from surface waters. The entire garden area (albeit small in nature) was all to be paved as well, reducing the available exposure pathways to any contamination that might remain.
  • The presence of the Langley Silt Member reducing the migratory pathway between any Made Ground (if present) and the Kempton Park Gravel Member. The adjacent site investigation logs also confirmed the presence of the Langley Silt Member to depths between 1.70 – 2.00m bgl.

Following our contamination risk assessment, it was determined that no Site Investigation was required from a contamination perspective.

We determined that the client needed to provide an asbestos survey for the current building and for a discovery strategy to be implemented to ensure that as part of construction works, should any unexpected contamination be identified, it would be dealt with appropriately.

The next hurdle was getting this approved by the Environmental Health Officer (EHO), who is notorious for causing delays to projects. Whilst the Local Planning Authority must work proactively and in a positive manner with the applicant in accordance with the requirements of paragraph 38 of the National Planning Policy Framework (2021), this is often not found to be the case. The council’s EHO always provides hurdles to jump over, which is their preference rather than following industry guidance to proactively find a sustainable solution. Whilst this is tricky to overcome especially when vague minor queries are common, we meet with the EHO to allow for elaboration of the objections to find a way forward with each project we work on in this council.


The Outcome

Our quick, cost effective, site specific and highly detailed desk study allowed the client to save on the cost of a site investigation, which would usually be required by this council. Our risk assessment and discovery strategy were accepted, allowing the client to proceed with the project.

Pin It on Pinterest