The Environment Agency funded the £1.4m anti-flood measures to build a new culvert and re-direct the original stream from a local nature reserve, Mousesweet Brook. This is to help prevent the risk of flooding to the surrounding houses and businesses. Councillor Khurshid Ahmed addressed the concerns of the culvert by stating. “The existing culvert is made of brick and as a result has deteriorated over the years, reducing the flow of water and making it more prone to blockage. We want to carry out some work there to minimise the risk of flooding to nearby residents by replacing the culvert.”
Forkers Limited approached Enviromesh to design, supply and install four separate 5m high Mass Gravity Gabion Retaining Wing Walls. These were to go on either side of the culvert entrance and on both the north and south side.
WORKING ON-SITE
Site access was the main concern due to their being one main route to manoeuvre around the site. As a result, getting machinery and supplies to the north side of the wall cause a concern. Along with other contractors working on the same site, this resulted in a congested working space. Enviromesh always undertakes extra precautions and assessments to ensure the health and safety of workers. The installation team follow strict health and safety guidelines in addition to any site-specific conditions.
With a number of other contractors working at the site in a different capacity. The local restrictions in working space and access resulted in a certain amount of congestion. This required additional management in terms of communication and coordination with the other site workers.
To solve the site access issues, Enviromesh would commence works once the culvert was in situ. Rerouting of the brook during the construction period ensured a reduced amount of water in the working area.
WING WALLS
A total of four flush-faced Mass Gravity Gabion Retaining Wing Walls; using 2.7mm wire diameter mesh baskets with a 3.8mm facing mesh, coated with a grey PVC organic polymer powder coating; were installed at Mousesweet Brook. The design life for this specification is 120 years in a mild environment. Each wall was 4.5m high and varied in length from 6m to 10m. A nonwoven, needle-punched geotextile membrane placed between the gabion baskets and the 6N backfill to prevent fines washed through, causing settlement. The gabion baskets included a total of 440 tonnes of typical 6G gabion graded stone (100mm to 150mm in diameter). The key properties of the stone are that it is hard, durable and irregular in shape to ensure a good interlock. Therefore reducing the potential for movement and settlement within the wall.
WILDLIFE
Due to Mousesweet Brook being a local nature reserve, there is a high volume of Kingfishers nesting in the area. Enviromesh included this into the design of the gabion baskets. While on site the 150mm x 150mm sections were cut out of the baskets in each wing wall. These allowed for the installation of three 100mm diameter by 1000mm length nesting pipes at various heights. This allowed for a safe place for the Kingfishers to nest, away from other wildlife in the area.
