Full Excavation Under Watching Brief
By Jennifer Holmes

Full Excavation Under Watching Brief

case study: Watching Brief on excavation project for commercial developer

Japanese Knotweed Ltd (JKL) was contracted by a commercial client to provide a Watching Brief service for full excavation and removal of what we estimated would be over 963 tonnes of contaminated soils.




the site

The land consisted of various plots north and south of a public footpath that were previously used for industrial purposes. The client’s ecologist report had identified Japanese knotweed on the land which our surveyors then outlined as four stands of knotweed.

The challenges

This was a site with several challenges and considerations. Precautions were needed to be included in the risk assessment regarding a public footpath running through the site which either it had to be temporarily closed off or fencing erected around the sites. The knotweed had previously been treated as well as disturbed, so it was difficult to estimate the extent of the underground rhizomes. Bonsai growth was notable evidence of the previous treatment. Additionally, our site assessment showed there were underground services running through the site, mainly gas pipes, and several trees in the knotweed areas that the client had felled, all of which required navigating.

our solution

Before works could commence JKL delivered a toolbox talk to the site team to explain the process, procedures, health and safety aspects and biosecurity measures they should follow, and, they must all sign up to the specific RAMS provided. Because of depth of excavation – due to the deep rhizome growth, a 4-metre root barrier was required. All underground services had to be capped off before we could carefully excavate around them to enable us to fit the root barrier. Contaminated soils were removed from site and disposed of at a licensed landfill.

What is a Watching Brief?

A Watching Brief is a collaboration between JKL as experts in the field, and the client who may have the equipment for the project but not the qualified teams to carry it out. Before any watching brief contract begins the client will inform us of their requirements and expectations, and the team that will be carrying out the excavation. We equally require information on the type of machinery they plan to use to ensure it’s fit for the job and in line with our recommendations.

Read the full case study for all details of our Watching Brief service.


Read the full case study to see why Watching Brief is a great option for developers