Erosion Protection on the River Leith, Thrimby, Network Rail - Salix Solutions

Network Rail had identified an erosion and scour risk at the toe and embankment of one of their assets on the River Leith, near Thrimby, Cumbria.

Train passing above the River Leith

RockLock in action Erosion protection on the River Leith for Network Rail

RockLockTM providing erosion protection

Rock Rolls providing erosion protection

Erosion control work with train passing

RockLock in action

RockLockTM providing erosion protection

Rock Rolls providing erosion protection

Salix were requested to work with Network Rail to provide an environmentally sensitive solution to address the issue.

The solution consisted of using Salix’s RockLock^TM – a combination of Rock Rolls and ground anchors to provide an ultimate fixing solution in high-energy environments. Given the flow velocities, ground anchors help to prevent the movement of the Rock Rolls.

RockLock^TMrequires significantly less material than traditional alternatives such as gabions, rip rap, and block stone. In this instance, a single 250mm surface layer of RockLock^TMwas installed. The RockLock^TMsolution resulted in an overall reduction in time and cost of construction, whilst providing a carbon footprint reduction compared with traditional alternatives.

The small stone grading found within Rock Rolls and Rock Mattresses allows for greater sediment accretion, vegetation establishment, and colonisation by benthic invertebrates compared with larger stone. As sediment accretes and vegetation establishes through, this helps to provide a continuation of the river habitat corridor.

Rock Rolls and Mattresses utilise a UV-stabilised virgin HDPE net containing a 40-80mm stone. Virgin HDPE has an estimated design life of up to 100 years.

Further up the rail embankment, TerraLock^TM was installed to stabilise the slope and provide geotechnical stability from shallow slips. The VmaxC350 Turf Reinforcement Mat was used in this instance, allowing vegetation to establish through the Vmax while providing long-term bank stabilisation and erosion protection.

Products Used

Rock Mattress installed Lockwood Reservoir with built in lifting strops

Pre-filled Rock Mattresses

Rock Mattresses are a robust and permanent revetment for use around reservoirs, shorelines, lake edges, streams and river banks. They are cost-effective revetments that are suitable alternatives to rock rip rap and gabions…

VMax³ C350

VmaxC350 is a permanent Turf Reinforcement for reinforcing soils. The VmaxC350 incorporates a coir fibre layer to provide instant erosion protection, whilst the three-dimensional grid provides significant long-term protection.

Rock rolls provide an instant flexible solution to many scour problems

Pre-filled Rock Roll

Rock Rolls are a robust and permanent revetment for use around reservoirs, shorelines, lake edges, streams and river banks. They are cost-effective revetments that are suitable alternatives to rock rip rap and gabions in many scour applications.

Details

Client: Network Rail
Location: River Leith, Thrimby
High Energy Rivers, Rail, Rivers & Water Courses

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

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 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

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

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

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

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