Soft engineering solutions presented by Salix, such as Coir Rolls, Rock Rolls and shear stress turf, represent a major cost saving over traditional hard revetments
Salix assisted with providing a solution for a new commercial development, providing simultaneous erosion control and environmental benefits.
This solution provided a continuation of the habitat whilst also achieving the requirements for erosion protection.
Salix were involved with an embankment restoration project, the supply and install of Shear Stress Turf, Coir Rolls and Rock Rolls, at River Stour Kidderminster. The opportunity arose from a new commercial development.
The project consisted of regrading the banks of an urban section of the river Stour, where Salix materials were supplied.
Due to the nature of the enclosed site and the requirement for flood defence along the River Stour through Kidderminster, there is limited ability to restore this river habitat, however these habitats have a high ecological value and provide important habitat for fish and invertebrates.
The design philosophy for the project was to provide effective erosion protection, whilst ensuring flood capacity was retained and to increase the ecological value of the watercourse.
Riverside planting in an urban watercourse requires prudent choice of plants, which may be tolerant to shade and high energy water environments. Pre-established coir rolls increase planting success, as the plants are mature which helps to reduce risk of plant failure. Adequate toe protection was required to protect the vegetation from high flows during peak events.
The face of the embankment was vegetated using Salix’s pre-grown Shear Stress Turf to ensure that soon after installation the vegetated embankment would be robust enough to thrive in periods of high flows which have the potential to occur quickly.
Rock Rolls and Coir Rolls are used in conjunction on the project to provide mature vegetation, whilst also protecting the bank from erosion. Plants were pre-established in 300mm diameter biodegradable Coir Rolls, placed behind Rock Rolls.
The plants had to be sufficiently robust to survive periods of high flows. Salix’s pre-established coir rolls are planted are typically grown for 8-12 months, providing mature native vegetation to increase success. Himalayan Balsam is present in the area, so mature vegetation helped to reduce the dominance of invasive species.
The Shear Stress Turf was planted with a riverbank mix, consisting of a species rich seed mix.
The Rock Rolls utilise a 40mm to 75mm graded stone, providing robust erosion protection whilst allowing vegetation to establish. The small stone also increases the abundance and diversity of benthic invertebrates due to the larger surface area for them to colonise compared with traditional alternatives. The plants found within the coir rolls will colonised the wider area, including the rock rolls, providing greater ecological value.
The high erosion control performance of the solution meant that a bioengineered solution was suitable as a direct alternative to rip rap. This saved the need for tonnes of imported material whilst creating sustainable and ecologically valuable solution. The shear stress turf provides long term erosion protection and vegetation establishment while permanently reinforcing vegetation.
The various soft engineering solutions presented by Salix represent a major cost saving over traditional hard revetments.
Your staff are always friendly, knowledgeable and helpful and we have always been pleased with the service and the quality of the wetland plants and planting services. Technical knowledge on erosion control is also excellent. Keep up the good work!Living Water Ecosystems Ltd
Excellent overall performance – very approachable and offered a good sustainable solutions to rectify a significant erosion scour to the river foreshore without comprising the existing flood defence. Carried out work to agreed timescale and budget. Certainly would value their future input.Environment Agency, Leeds
We have worked with Salix on a number of projects throughout East Anglia over the last 6 years, and we have always found them to be highly professional and competent. We have used their services as suppliers of quality wetland plants, with a traceable provenance, and as contractors to both supply and plant the wetland plants. In addition we have always relied on the technical advice and knowledge of David Holland, in particular, to help answer queries from our clients regarding wetland planting schemes we have been involved in, this is an added value part of their service, for which we are grateful.UPM Tilhill
HydraCX gave an immediate impression the embankment was grassed, making it more visually pleasing to our travelling customers. The rapidity of grass growth was exceptional and it added additional strength to the slope surface.Network Rail
Atkins has worked with Salix on a number of projects, collaborating on design concept, trialling and implementation. We have found their experience valuable in delivering cost effective and environmentally functional solutions.Atkins
We used HydraCX for the first time on a Network Rail project in Chipping Campden. We wanted to establish vegetation growth as quickly as possible on a slope with poor ground conditions without the need for importing topsoil due to possession time constraints. HydraCX provided an excellent growing medium for rapid germination.Carillion Rail
We invited Salix to re-landscape the watercourse through a design and build project. The works to the watercourse were completed within two weeks of starting on site and, despite a number of prolonged heavy rain events both during and after the works, the pre-established coir rolls and pallets all began putting on new growth within a matter of days providing the watercourse with instant channel vegetation and protection to the toe of the banks. The VMax reinforcement used to stabilise the slopes has also prevented any erosion to the sandy soil beneath and has allowed the rapid establishment of grass which wouldn’t have otherwise been possible.South Ribble Council