News

Pix Brook Bank Reinforcement
May 23, 2019

Background

The landowner of a length of the Pix Brook approached RAB to seek advice on a failing riverbank.  The bank had suffered from erosion and was formed of a near vertical, unstable slope.  The bank supported a car park that was adding to the problem due to the weight of the car park and parked vehicles.

gabions

In order to try and improve the situation, the landowner installed stone filled gabion baskets along the riverbank.  However, the gabions were incorrectly installed, bulging and effectively reduced the channel capacity.  Additionally, the gabions had not been consented by the local authority.

The Challenge

The landowner asked RAB to design a solution to the satisfaction of the local authority and obtain an Ordinary Watercourse Land Drainage Consent.

Key to meeting the requirements of the local authority were the restoration of the channel capacity and a hard-engineered solution to stabilise the bank.  Removing the gabions would potentially increase the risk of collapse due to the height (>2.5m) of the bank at that location. As such, attention to detail was crucial for a successful outcome.

The Solution

PilesThe proposed river restoration solution aimed to integrate heavy engineering with soft engineering, while improving amenity in the area. As such, the selected solution included the installation of steel sheet piles in combination with soil erosion control measures (Geoweb and Geojute) which would allow vegetation to be re-established.

The sheet piles were used to support the bank during construction, provide robust retention of the land behind and also to protect the health and safety of site users in the long-term. In addition, the car park was reinstated into a greenfield amenity area with bollards at the entrance to prevent parking. RAB tendered the construction work with Greenford Ltd being the successful contractor.  RAB acted as the Project Manager and Supervisor under the NEC4 Engineering and Construction Contract on behalf of the client. The proposed restoration works were completed successfully, with the reinstated bank looking much healthier whilst offering a long-term engineering solution to the stability of the Pix Brook.

The design and site supervision were undertaken by Alexandros Tsavdaris, RAB Senior Flood Risk Engineer, with Ray Pickering, RAB Director of Flood Risk Management as Project Director.

Alex & Ray