Klargestor Separators

Sediment Management and Aquatic Restoration Concept Overview

Further to the queries received from local residents in relation to Goodwin’s Pool, I am happy to provide the following reassurances in relation to how our site impacts on that pool:

SW Outfall & Goodwin’s Pool

David Wilson Homes (DWH) can confirm that we have consent from the LLFA at Cheshire East Council to discharge the Black Firs development’s surface water drainage into the Congleton Anglers Association Pond (also known as Goodwins Pool). These works also include the construction of a new headwall (outfall) into Goodwins Pool.

Goodwins Pool – DWH can confirm that we have been in communication with the Congleton Anglers Association (CAA) for over 12 months and as part of a separate agreement between DWH and CAA we have agreed to undertake silt removal works within the Goodwin’s Pool to enhance the ecological value of the pond and to improve oxygen levels within the water.  Our contractors Ebsford Environmental carried out the de-siliting works in November 2017 and these works are now complete.  We can confirm that there has been a loss of fish within the pond as a result of these activities and whilst the exact numbers cannot be determined it was unavoidable and expected that there would be a loss of fish.  As a gesture both David Wilson Homes and Ebsford have agreed to contribute financially to CAA for the cost of re-stocking of fish to the pond.  The CAA are scheduled to hold a meeting between club members on the 22nd February and DWH’s financial contribution will be discussed at the meeting and we await further comment.

Environment Agency – The EA visited Goodwin’s Pool on the 19th February to undertake a survey of the fish levels.

Outfall – We can confirm that DWH’s contractor (MV Kelly) have commenced with installation of the surface water outfall connecting the new development with Goodwins Pool.  To facilitate these drainage works MV Kelly have installed a pump system to discharge surface water into the pond.  We can confirm that Silt-Mitigation measures have been installed to prevent silt from entering the pond, these measures include the installation of 3 number settlement tanks (designed to capture the silt) and ensure that the surface water entering the pond is as clean as it can be.  The outfall works are programmed to be complete by the 2nd March.

Silt-Mitigation Measures – There are 2 phases to the silt mitigation measures that are designed to ensure the prevention of silt and sediment from entering Goodwins Pool.

The first phase is the ‘Construction Phase’ – these measures will be put in place and maintained for the duration of build activities on site.  These measures include:-

  • Installation of temporary gulley bags to the road gullies (designed to capture silts that enter the road gullies)
  • SuDs Pond (on-site) – As part of the approved SW drainage strategy we are to install a new attenuation pond on site.  The pond contains an inlet and outlet.  We will be installing ‘sedimats’ at both the inlet and outlet of the pond.  The sedimats are designed to capture silts and sediment that may have entered the on-site attenuation pond.
  • Silt Trap Interceptor – It is proposed that a Silt Trap Interceptor will be installed between the attenuation pond and the outfall into Goodwins Pool.  The interceptor is designed to capture fine silts that before they reach the final outfall (Goodwins Pool).  The interceptor is also designed to collect at ‘oils’ that enter the surface water system from motor vehicles.

Sedimat ‘link’: https://www.hy-tex.co.uk/docs/biodegradables/sedimat/b_sedimat_01.pdf

Second Phase (Post Construction) – Upon completion of the development, all the roads will be final surfaced and the volume of contruction debris will be significantly reduced.

  • Temporary Gulley bags – to be removed
  • Landscaping within the pond will be established – The planting of grasses and reeds within the pond not only provide an aesthetic function they also are designed to provide an infiltration medium to ensure silts and sediment are collected within the pond and provide nutrients to the grasses.

Management – During the construction phase of Black Firs development, DWH will be responsible for ensuring that the surface water drainage is installed to the approved standards.  DWH will also be responsible for silt management to ensure that silt control and mitigations measures (as above) have been installed and are being maintained.  These will involve weekly checks by the Site Manager.

Long term Management – Once all properties are occupied DWH will hand over the open space areas which include the surface water outfall to a Management Company.  The management company will be responsible for the long term maintenance and management of these areas once the development has been completed. All residents on site will contribute financially via an agreed Service Charge.

DRAINAGE DESIGN EXTRACT – On site attenuation pond (SuDs) and outfall

Apologies for the level of detail above and attached, but I wanted to provide full reassurance that all works are authorised and are being carried out properly and professionally.

Should the Parish Council have any further queries in this regard, please do not hesitate to ask.

Regards

Andrew

Andrew Taylor BSc (Hons) DipTP MRTPI
Planning Director
Barratt & David Wilson Homes North West