Green-tech products incorporated into Derbyshire flood scheme

roject: Cuttle Brook Flood Alleviation Scheme

Location: Sunnydale Park, Derby

Client: Derby City Council

Main Contractor: NT Killingley

Products/Services Supplied: Green-tech Coir Log Roll Bank Stabilisation, Tree Guards, Stakes and Belting

Green-tech products incorporated into Derbyshire flood scheme to bring environmental and biodiversity improvements

Sunnydale Park is a local nature reserve and recreational area which forms part of a green corridor linking the Derby suburb of Littleover with the surrounding countryside. As part of the park, Cuttle Brook runs from a culvert down into a pond that was created in the 1980s as part of Derby’s original flood alleviation scheme.

Funded by Derby City Council with support from DEFRA and the European Regional Development Fund, a £1.176m scheme was approved to further reduce the level of flood risk in the local area, improve water quality in Cuttle Brook itself, and provide additional environmental and biodiversity improvements in the park.

The plan was to create additional flood embankments around the park and increase the amount of water that can be stored by adding a second pond that the brook initially runs into. Additional wetland area was added to include native wetland plants and reedbeds.

Over 3000 square metres of wetland will help to attract shrews, frogs, toads, newts and dragonflies. It will also help improve the water quality in the brook and ponds by filtering out sediment and pollutants. The resulting increase in wildlife, fish and invertebrates will then help to support a wider range of species such as birds, batts, amphibians, and reptiles.

Additional lowland meadow and new tree planting gives welcome aesthetic and biodiverse benefits, providing a valuable habitat for birds, bees, and insects.

Green-tech involvement:

The creation of the new wetland areas involved a great deal of re-shaping and stabilisation of the banks along the brook and around the ponds. Long-established Chesterfield based landscaping business, NT Killingley was appointed to handle the landscaping, and with a 17-year working relationship with Green-tech, we were asked to supply the necessary materials.

The ponds and water course consist of shallow riffles to help oxygenate the water, deeper pools to provide cooler water, along with wide shallow margins to provide warmer water and areas for plants to grow.

For the banks of the brook and ponds, Green-tech supplied nearly 300 metres of pre-established coir rolls, each pre-planted with 18 plants, including carex acutiformis (lesser pond sedge), juncus inflexus (hard rush), lythrum salicaria (purple loosestrife), iris pseudacorus (yellow iris), and Phalaris arundinacea (reed canary grass).

The gtCoir Log Rolls are perfect for establishing natural marginal vegetation around lake edges, streams, and riverbanks. The compressed coir fibre is encased in a woven coir netting and is available either pre-planted as in this case, or unplanted for nature to take its course. Available in 3m lengths, and 200 or 300mm diameter, they provide a stabilising barrier to be built up against, providing both erosion control and rapid vegetation establishment.

For the extended reed beds, 150 metres of coir plant pallets were laid, pre-vegetated with phragmites australis (common reed), that can grow up to 6m tall. Very similar to the Log Rolls, the pallets are compressed into mats 2x1m and can be supplied pre-seeded or natural.

As part of the wetland improvements, the flood basin was planted up with additional trees, resulting in more than were there before the improvement works. Green-tech is the UK’s largest supplier of landscape products, and tree stakes, guards, and belting are some of the biggest selling product lines, not only helping the trees become established, but also protecting them from some of the more herbivorous wildlife. Completed at the end of 2021, the improvement scheme at Sunnydale Park has resulted in an overall Biodiversity Net Gain and been supported by Derbyshire Wildlife Trust.

Alasdair Innes, Green-tech Specification

"This was a lovely project to be involved with, and to visit one year later to see everything becoming so well established is great to see. There was certainly plenty of wildlife about with an abundance of butterflies and dragonflies, and it will only look better as it becomes more established."