Protecting Wildlife for the futureRegisered charity no. 222212
The aim of the project is to reinstate an online pond on the Burley Brook to provide additional wetland habitat.
As part of the desk study consultation undertaken as part of the Wild About Ponds project across Derby City, it was identified that a small online pond with a surface area of approximately 50m2 had been created on the northern bank of the Burley Brook at grid reference SK 35010 40995. (See Map 1)
Personal communication with Alf Bousie, the Principle Landscape Assistant within the Neighbourhoods department of Derby City Council, confirmed that the original pond had been dug out approximately ten years ago and recent visits had revealed that the pond had largely become infilled as a result of silt deposition.
It was agreed that the pond should be re-excavated to form a slightly larger pond than the original using a small mechanical digger. It was intended to position wooden sleepers across the brook slightly downstream of the concrete plinth which had been used originally to dam the brook but which had now slipped.
Before the commencement of any work, an ecological survey of the site was carried out to identify any nature conservation interest which had developed on the site. The results of the survey were used to inform the preparation of a method statement to minimise any potential ecological impact and retain any ecological interest which may be present.
A survey visit was undertaken on 30th March 2010.
The survey identified that the pond had become infilled through silt deposition with no standing open water present and the concrete plinth which had been used to dam the brook had slipped, thereby negating its function to restrict the flow of water.
Vegetation within the former pond area comprised largely of Creeping Buttercup, Common Nettle and Reed Canary-grass. Occasional species include Angelica, Great Willowherb and Yellow Iris. Small quantities of Brooklime and Opposite-leaved Golden Saxifrage were also present.
No amphibians or aquatic invertebrates were noted.
Prior to any excavation it is proposed to remove the plants of Brooklime, Opposite- leaved Golden Saxifrage and Angelica in order that they may be retained and re-planted on the margins of the new pond. Similarly, specimens of Reed Canary-grass and Yellow Iris will be removed, retained and re-planted.
The positioning of concrete sleepers to form a dam across the brook will be undertaken in consultation with the Environment Agency.
A mechanical mini-digger will be used to excavate a new pond in the same area as the existing infilled pond with slightly larger dimensions. The pond should have a maximum depth of approximately 1m and the work should not involve the removal of any extra sections of the northern bank of the brook. Excavated material should be used to form bunds on the west and eastern banks of the pond and the opportunity should be taken to create a range of bank profiles from shallow margins to the north (field side) to steep banks on the east and western banks.
Apart from the localised translocation of plants removed from the excavated area there should be no additional planting. This will allow for natural colonisation to take place, particularly with regard to aquatic flora which exists in the area of marshy ground located a short distance upstream of the site.
Management works to the pond site were successfully carried out during May 2010 in accordance with the Method Statement set out in the April 2010 Wild About Ponds Project Report with the exception of the positioning of concrete sleepers to form a dam across the brook. It was agreed prior to the commencement of the work to omit this part of the proposal as it was considered to be unnecessary.
Clearance of pond – May 2010
Re-planting of pond – May 2010
A number of aquatic plant species present within the area of the proposed pond site were uplifted by BTCV (British Trust for Conservation Volunteers) and stored prior to their re-planting once the excavation of the pond had been completed by digger.
A monitoring survey visit conducted on 25th March 2011 identified the presence of common frog and one clump of frogspawn together with the satisfactory establishment of aquatic plant species.
A visit on 12th March 2012 recorded the presence of 12 clumps of frogspawn during which it was also noted that silt deposition had seriously compromised the depth of water in the pond, particularly in the area where the brook fed into the water body. A range of aquatic plant species were still present including Great Willowherb (Epilobium hirsutum), Yellow Iris (Iris pseudoacorus), Soft Rush (Juncus effusus), Conglomerate Rush (Juncus conglomeratus), Floating Sweet-grass (Glyceria fluitans), Brooklime (Veronica beccabunga) and Water Figwort (Scrophularia auriculata).
Later in 2012, a visit to the site on August 23rd, identified that the pond had been virtually completely lost to silt deposition. It is likely that the loss of the pond to silt deposition had been the result of periods of exceptionally high rainfall during the summer months. The flood conditions had caused increased silt loads within the brook and had also deposited debris and plant material within the former line of the brook essentially diverting the course of the brook through the pond.
It was recommended that works should be carried out to re-instate the former line of the brook and remove silt from the pond to re-create areas of open water.
The former line of the brook was re-instated by Burton Conservation Volunteers on 11th November 2012 together the creation of a slack water inflow into the pond to minimise the amount of silt deposition in future years. Some debris and silt removal was also carried out but, during the work, it was determined that the amount of silt was too great for its complete removal by manual means.
It is therefore recommended that the remaining quantity of silt in the pond should be removed by mechanical digger during the autumn period.