Case Study

Case Studies – Celtic Technologies

Client: Celtic Technologies

Project: Gladstone Street, Warrington

Services: Japanese knotweed removal: – reduced excavation and installation of a root membrane.

The Challenge: The challenge was to treat approximately 1,000m2 of aboveground Japanese knotweed growth, mainly along the upper bank of a former railway line.

The proposed development of the site involved constructing three blocks of flats on the higher ground, with a car park and water attenuation system on the lower land, i.e. in the knotweed area. The client wanted a cost effective and quick solution to the Japanese knotweed problem.

Our Solution: The proposed approach was to fully excavate the knotweed growth on the higher ground under the proposed flats and undertake a reduced excavation and installation of a root barrier membrane along the former car park area. The site would then be monitored to ensure no regrowth.

A cut and fill option was used for the reduced knotweed excavation method as land at one end of the knotweed area required lowering, while it required raising at the other end due to the requirements of the water attenuation system. Only a small amount of excess excavated material was removed offsite.

A horizontal root barrier was installed across the knotweed reduced excavation area and was covered with sand. A vertical root barrier was installed along the bank of the knotweed area to stop any knotweed growth migrating into the area of the new flats. The area is now part of a monitored programme to ensure no re-growth occurs.