Fishace Ecological Engineering

The Earth Centre site is in the valleys of the rivers Don and Dearne in the Magnesian limestone country to the west of Doncaster. The area - once of great beauty, to which it is rapidly returning - was severely damaged over the last 150 years by coal mining and other industries. For the past ten years (since the mines closed) the site and its immediate surroundings have been the subject of widespread remediation and regeneration by Doncaster Council and, more recently, the Earth Centre itself with generous financial assistance from English Partnerships, the Forestry Authority, the Countryside Commission and many smaller organisations. Despite the former industrial activity, there are extensive areas of natural grassland, woodland and water on the 400-acre site, some of which is designated as Sites of Scientific Interest (SSIs), or Special Scientific Interest (SSSIs).

As an essential element of earth sciences, it is recognised that water is a significant aspect of The Earth Centre project. The 320 acre site embraces the River Don, the River Dearne, the Sheffield & South Yorkshire Navigational canal, two recently constructed wetland areas and an Aquaculture Centre.

3.2 Aquaculture Centre

The site comprises of damaged former colliery land interlaced with fine ecologically diverse habitats embracing woodland, rivers, wetlands and magnesium limestone outcrops. Three major water courses traverse the land namely The River Don, The River Dearne and the Sheffield & South Yorkshire navigational canal with dispersed pockets of wetland habitat throughout the site. Quite by chance the location is positioned approximately 700 metres south-east from the site of a series of 18th Century fish ponds at the village of Skitholme now buried under the large coal waste area adjoining the west bank of the River Dearne. The 5.6 hectare Phase One North sector of the site it was previously utilised for coal tipping and slurry ponds. The existing soil structure beneath the floodplain comprises of 3.0m of made ground consisting of grey sand, gravel, ash, silt, clay and other fragments of building materials. The area of the Hatchery and the Nursery Ponds where situated in the central devlopement area on the north bank of the River Don.

3.3 Circle Tip

Located at the western end of the site, between the river Don and the South Yorkshire navigational canal is the (or Red Rose Field) . The area was formerly part of the coal spoil tip for Denaby Main colliery, where most of the discarded material was removed during the reshaping of the Hull / Barnsley tip to the north of the site. The Circle Tip now area forms part of the river Don flood defenses. This has left the site contaminated with heavy metals and coal spoil and has reduced the potential productive or recreational usage of the area. The wetlands cover an area of 4.7 hectares. and consisting of ten ponds, shallow water areas and open mud for waders, also three islands have been created and planted with trees. The wetland is surrounded by grassland which was previously cut for hay. The landscaping was carried out over the winter of 1994/5 and the seeding of aquatic plants over the same period with the introduction of pot grown plants in the summer of 1995. This will provide invaluable information as to the most effective method of establishing a plant community in a newly created wetland site. The objective is to create a self sustaining system where it can be shown that wetlands can be be productive and effective in eco-sensitive wetland systems and show that 'conservation can and does pay'. Plants grown here will be utilised in other areas of the site and some will be retailed. Fish from the production facilities in the central area of the site where grown on in the ponds and harvested on a regular basis, sold as food fish to the restaurant on site and for retail sales for stocking fisheries. Accompanied tours are organised to the wetland area and in the future there will be a self guided trail taking in the wetlands, riverbanks and the forestry area to the west of the wetlands.

Consequently there exists a rich variety of habitat embracing biodiversity, conservation, and educational awareness of these aquatic features.

3.4 Water Quality

The analysis of water source quality formed a base model to identify certain pollutive elements and by the introduction of eco-treatment processes achieve optimum standards for fish culture.

Water quality sample statistics River Don water quality analysis (source Yorkshire Water Authority)
3.4.1 The River Don sample point at Mexborough Power Station
Samples taken from 01/01/93 to 31/12/93

Element Units Minimum Maximum
Lead total UGH/L 4.49 11.1
Water temperature Celsius 5.0 18.5
Oxygen Dissolved % saturated 53.0 105.0
Oxygen Dissolved MG/L 5.0 13.4
pH pH 6.03 7.63
BOD Total MG/L 2.1 10.1
Suspended Solids MG/L 7.0 131.0
Nitrate MG/L 3.05 12.36
Ammonia Unionised MG/L 0.0001 0.051
Chloride MG/L 61.80 249.0
Phosphate MG/L 0.12 2.14
Magnesium Total MG/L 11.6 25.3
Anionic detergent MG/L 0.08 0.36
Cadmium Total UG/L 0.1 0.508
Copper Total UG/L 5.32 13.3
Zinc Total UG/L 26.0 65.0
Chromium Total UG/L 2.06 7.27
Iron Total UG/L 535.0 1210.0
Nickel Total UG/L 25.6 92.4

River Dearne water quality analysis
3.4.2 The River Dearne sample point at Pastures Bridge
Samples taken from 01/01/93 to 31/12/93

Element Units Minimum Maximum
Lead Total UG/L 1.69 10.7
Water temperature Celsius 3.0 18.0
Oxygen Dissolved % saturated 56.0 100.0
Oxygen Dissolved MG/L 5.4 12.8
PH pH 6.09 7.82
BOD Total MG/L 2.7 11.1
Suspended Solids MG/L 5.0 248.0
Nitrate MG/L 5.65 14.45
Ammonia Unionised MG/L 0.0001 0.0101
Chloride MG/L 67.0 286.0
Phosphate MG/L 0.13 2.46
Magnesium total MG/L 12.2 46.4
Anionic detergent MG/L 0.07 0.33
Cadmium total UG/L 0.1 0.288
Copper total UG/L 5.52 19.9
Zinc total UG/L 20.0 49.0
Chromium total UG/L 1.0 4.34
Iron total UG/L 551.0 3910.0
Nickel total UG/L 9.01 16.0

3.5 Summary of water quality analysis

The Rivers Don & Dearne has been historically polluted since the onset of the 19th Century Industrial Revolution. Up to a period of seven years ago the rivers where evaluated as Class 4 (poor quality) water courses. Presently they exist as Class 3 rivers and expected further improvement will attain a Class 2 (fair quality) status by 1996. Both rivers contain a high incidence of iron and other heavy metals due to mine water seepage. To accurately assess river bed pollution and the safe disposal of basal dredgings further analysis of river sedimentation is required. Aquacultural design considerations for the centre was given to the following points:

1. Higher normal levels of heavy metals including Arsenic, Cadmium, Copper, Nickel, Zinc and water soluble Boron in the existing ground.

2. A 1.5 metre rise in flood water from the River Don based on a one in hundred year flood event.

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