Court Hey Wetland Project, Knowsley

Client:Mersey Rivers Trust in partnership with Knowsley Council 
Final Value: £21,943
Start Date: Mar 2021
Status: Mar 2021

CCNW Solution

Construction of wetland 

The CCNW conservation team carried out excavation and construction of the new wetland in accordance with the specifications and design provided by Mersey Rivers Trust. Creation and enhancement within the existing natural wetland/bog area will maximise its potential for habitat diversity whilst decreasing flood risk within the park. The works created a more natural course to meander around the existing mature tree line within the wetland area of the park and link to the existing Court Hey Brook with an inflow and an outflow. 

The new wetland was excavated to approx. 25m wide in places and approx. 120m in length, to a depth between 700mm -1.2m. The newly created banks of the wetland were formed with a slope of no less than 1:5. The creation of the new wetland within the site enabled CCNW to open up the existing land drains allowing drainage waters to flow into the wetland habitat, filling it up with water. 

Removal of spoil 

All excavated materials were retained on-site and distributed to adjacent land between the footpath and the wetland. CCNW carried out minor landscaping works on this section, which included building up the levels and re-grading the sides of the wetland. These areas were left ready to apply grass seed, meadow mixes, and for re-planting. 

Construction of inflow and outfalls

CCNW carried out the installation of inflow and outfall culverts within the wetland, comprising a 15m x 225mm long pipe and Soluform bags to create a headwall around a 225mm pipe within the Brook and linked to a concrete headwall with Kee Klamp handrail position around the inflow culvert which links the newly created wetland.

At the far end of the wetland, a second concrete headwall with a left-hand angled headwall pre-fitted with flap vale was installed within the brook linked to the pipe and a standard concrete headwall with hinged grating. This will allow the free flow of water back into the brook. 

Site clearance works

CCNW carried out the removal of several small trees as part of the wetland construction and any over-hanging large branches that might have hindered the operation of machinery. Any smaller branches that hindered safe operations were removed by hand. 

The CCNW team carried out further vegetation management works within the boundaries of the wetland including the removal of some aquatic plants from the existing bog area and relocating them within the wetland. 

Mersey River Trust with help from the local Court Hey Friends’ Group Volunteers intend to plant up the newly constructed wetland with common reeds which will act as a filtration system to improve poor water quality within the brook, this will also create better biodiversity for wildlife.