Client: Common Trustees Project: Assessment and Recommendation of Prickend Pond, Date: July 2012 Report: Recommendations for Restoration of Prickend Pond,
Wildfowl & Wetlands Trust (Consulting) Ltd accept no responsibility or liability for any use which is made of this document other than by the Client for the purpose for which it was originally commissioned and prepared. This document solely represents the views of Wildfowl & Wetlands Trust (Consulting) Ltd. Client: Common Trustees Project: Assessment and Recommendation of Prickend Pond, Title: Recommendations for Restoration of Prickend Pond, Issue: 1 Date: July 2012 WWT Consulting Wildfowl & Wetlands Trust Checked by: MB Slimbridge, Gloucestershire GL2 7BT, UK Approved by: EA T +44 (0)1453 891222 F +44 (0)1453 890827 E info@wwtconsulting.co.uk W wwtconsulting.co.uk Common Trustees Page 1 July 2012
Contents Contents Figures Tables Photographs 1. INTRODUCTION 2. METHODS 3. RESULTS Current site conditions and management Restoration plans and proposed actions from the Common Trustees Assessment of Current Plans Establishment of Marginal Vegetation Reducing/restricting bird feeding Re-profiling of margins Improvements to the SuDs System 4. CONCLUSIONS/DISCUSSION APPENDIX I. PHOTOGRAPHS APPENDIX II. FIGURES Figures Figure 1 Map of features and constraints at Prickend Pond, Figure 2 Possible development options for Prickend Pond, Tables Table 1 Estimated costs for design and restoration of Prickend Pond, Photographs Photograph 1 Example of bird feeding witnessed during the site visit Photograph 2 Low water levels at the pond from earlier this year (southern bank) Photograph 3 Low water levels at the pond from earlier this year (High Street end) Photograph 4 Outflow from the pond Photograph 5 Eroding pond edge Common Trustees Page 2 July 2012
1. INTRODUCTION 1.1 In June 2012, Wildfowl & Wetlands Trust (Consulting) Ltd (WWT Consulting) were contacted by Colin Yardley of the Common Trustees (CCT) to provide advice for the restoration of Prickend Pond, Common. 1.2 WWT Consulting previously provided restoration advice for a number of ponds and wetland features on the common in 2005 (WWT Consulting, 2005). Many of the recommendations provided in that report have been put into practice and improvements have been seen in the other wetlands and ponds on site. However, Prickend Pond suffers from a number of constraints and pressures leaving it in an unfavourable condition. Both the CCT and a recently created committee of local shop owners are driving for improvements to be made to the pond. 1.3 WWT Consulting was asked to review restoration plans and ideas developed by CCT and to provide expert restoration advice including any new proposals. 2. METHODS 2.1 WWT Consulting staff undertook a site visit, on the 26 th June 2012, to review the site and to photograph any key features and problems. The site was reviewed with Colin Yardley, Vice Chairman of CCT and Jonathan Harvie, warden and grounds keeper of the site. 2.2 All of the constraints at the site are reviewed in the following report with recommendations and suggested management changes that could improve the site. CCT s existing restoration plans will also be reviewed within this report to assess their suitability. 3. RESULTS Current site conditions and management 3.1 At present the site has a number of constraints and features that have a negative impact on its restoration and development. 3.2 Its location close to a road means that the majority of water entering the pond is runoff that has high nutrient and hydrocarbon levels. However, little silt appears to be getting into the ponds and the water is generally clear. No water testing has been carried out at this stage but a visual assessment of the site suggested that the water is relatively clean. One of the main conduits from the road flows through a sustainable drainage (SuDS) type system designed to treat the water before it enters the pond. At present reeds are only established at the beginning and end of the system where moisture levels are fairly constant. 3.3 Local residents enjoy feeding the resident Mallards Anas platyrhynchos and Canada Geese Goosey canadensis but continued feeding has made these species pests on the site while leftover food encourages rats to the site. Control of Feral Pigeons Columba livia and Brown Rat Rattus norvegicus is carried out on the site. The pond is an incredibly popular feature of the High Street and is heavily used as a place to sit during the day as well as somewhere to feed the birds. Photograph 1, Appendix I shows a typical example of the feeding problems on site. 3.4 Recent dry winters have resulted in low water levels throughout the year with the margins of the pond exposed. Photographs 2 and 3, Appendix I, show the pond from earlier this year when water levels were at their lowest. The pond has always been shallow and the abstraction of water by Thames Water has also had an impact on the water levels. Common Trustees Page 3 July 2012
3.5 The pond is an open system with a single overflow water level control. This is set at quite a high level and rarely overflows. Detritus from the pond currently gathers at this exit point and is skimmed from the pond on a regular basis by the full time maintenance staff (Photograph 4, Appendix I). 3.6 Attempts have been made to increase the amount of marginal vegetation though these have been hampered by the resident Canada Goose population which has grazed on the seedlings. Only three small patches of Yellow Flag Iris Iris pseudacorus have persisted, in areas away from the main feeding areas (Figure 1, Appendix II, points 3, 4 and 11). This side of the pond is perhaps the most promising as marginal vegetation has started to establish and there is minimal disturbance from people and geese as the footpath is narrow and unclear. The opposite side of the pond has hard concrete edges that are maintained by Bromley Borough Council. These show some signs of deterioration and have been known to crumble but they are maintained when problems occur (Photograph 5, Appendix I). 3.7 There are a number of large carp in the pond, of various species. The Environment Agency had previously removed some specimens but was unable to take all of the carp as many were hybrid species. A small number of Rudd Scardinius sp. are also present in the pond having been believed to be absent at the time of the previous WWT Consulting visit. 3.8 At the centre of the pond is a small island with some mature Willow Salix sp. trees present. Some concerns had been raised that the island was being eroded and reducing in size. However, historical photographs suggest that over the last 20 years there has been little reduction in size. The island is used by the ducks and geese as a roosting area and one pair of Canada Geese successfully used the island as a nesting spot this year. Other breeding birds on site include Mallard and Moorhen Gallinula chloropus. The Moorhen pair present made use of a bird house currently located adjacent to the island. Restoration plans and proposed actions from the Common Trustees 3.9 Following the previous consultation with WWT Consulting, the CCT have developed a number of potential restoration plans that it is hoped would restore the pond to an attractive and accessible feature. These include; Development of marginal vegetation around the pond, in particular in areas where it is starting to establish; Reduce the amount of bird feeding at the pond and restrict it to one area; Create a boardwalk or footpath area; Re-profile some of the steeper banks to create areas that would become wet during times of high water; and Increase the amount of vegetation in the SuDS system by trying to increase the residence time of the water. Assessment of Current Plans Establishment of Marginal Vegetation 3.10 The development of marginal vegetation is key to making the pond attractive and a more natural environment. It is recommended that any attempts to increase the amount of marginal vegetation are concentrated on the southern edge of the pond, away from the hard landscaped edge and the area most heavily used for bird feeding. Common Trustees Page 4 July 2012
3.11 Previous attempts to introduce marginal vegetation on this side of the pond have used logs to create enclosures which have then been back-filled and planted (points 3 and 4, Figure 1, Appendix I). This has had mixed success with one enclosure (point 4) developing a mixed stand of vegetation while only Yellow Flag Iris has persisted in another (point 3). The enclosure at point 3 is likely to have suffered from both grazing (by wildfowl) and shading from mature Willow trees on the bank. 3.12 Marginal vegetation is an excellent natural barrier to geese and, once established, will prevent geese from leaving the pond and accessing the banks. 3.13 To develop the vegetation on this side of the pond WWT Consulting would recommend the following actions; 1. Removal and thinning of large Willows. Where possible pollarding should be used to allow trees to remain in situ; 2. Creation of back-filled enclosures using either Coir rolls to form a barrier or logs as employed previously. Material for back-filling could come from re-profiling of either the southern bank or the section nearest the High Street, and 3. Plant the back-filled areas with a range of marginal and emergent wetland plants. Very few plants are able to withstand the pressure of grazing from wildfowl so it is vital that goose proof fencing and netting is employed. Details of costs and product specifications are given in Table 1. 3.14 The same methods could be used around the island in the centre of the pond to create a marginal fringe that would protect the island from erosion and also go some way to preventing geese from using the island as a breeding and roosting area. 3.15 Suitable plants that are more likely to survive pressure from wildfowl include; Cuckoo Flower Cardamine pratensis, Hemp-agrimony Eupatorium cannabinum, Meadowsweet Filipendula ulmaria, Greater Pond Sedge Carex riparia, Reed Canary-grass Phalaris arundinacea and Brooklime Veronica beccabunga. Reducing/restricting bird feeding 3.16 Bird feeding at the site is largely unavoidable as it is one of the main uses of the pond and one of the main reasons people visit the pond. Given that there is little opportunity to stop feeding altogether it is advisable that attempts are made to restrict the areas where feeding is carried out and to educate visitors about using appropriate food. 3.17 WWT Consulting would recommend the following actions to reduce the amount of bird feeding at the pond; 1. Try to restrict feeding to the northern and eastern edges of the pond along the concrete paths. Development of the site to introduce more marginal vegetation and other features should prevent people from feeding in other areas; 2. Create signage and interpretation boards that encourage the benefits of using grain instead of bread for bird feeding. This can also replace the sign warning about rats in the pond, and 3. Introduce grain dispensers that provide food. These can be simple coin operated machines that dispense a small amount of grain on deposit of a small amount of change (e.g. 20p). 3.18 Restricting feeding to these areas would hopefully reduce the amount of food left on the ground, as people would have to feed birds over the water. Making alternative food sources available would Common Trustees Page 5 July 2012
also reduce the amount of bread that is left on the ground a problem that was observed during the site visit (Photograph 1). 3.19 Should Canada Geese continue to be a major problem at the site then it is possible to obtain a licence for the removal of the species as a pest. Detailed information is given as a separate attachment. Re-profiling of margins 3.20 Re-profiling of the bank was discussed for two areas. The first is the area marked in Figure 1, nearest the High Street with the second on the southern bank of the pond, at point 9. 3.21 Changing the area closest to the High Street could help to give a more natural appearance and, hopefully, improve the aesthetic appeal of the area. At present this section is heavily grazed by the Canada Geese and is the main focal point for bird feeding activity. Re-profiling at the area around point 9 would make this side more accessible (with the introduction of a specific path or boardwalk) and would also provide material that could be used for any back-filling activities on the site. 3.22 In addition to re-profiling of the banks, plans to construct specific pathways or boardwalks were discussed. Boardwalks and platforms are excellent ways to manage pedestrian traffic as well as providing opportunities for people to feel close to water and immersed in habitats. A combination of a boardwalk and a platform could work very well over the area nearest the High Street as this could provide a focal point for visitors and help to protect any newly created marginal vegetation on a re-profiled section of bank. 3.23 Re-profiling would be a major undertaking at the pond and it is vital that local people that use the site are aware of any planned changes. Signage could be erected at the site and a public consultation held to canvass opinions and ensure that local people are aware of the proposed changes and have an opportunity comment on the process. 3.24 WWT Consulting would recommend the following actions as part of any proposals to re-profile the banks: 1. Draw up concept designs of the site to include visualizations of how the site will look after any development works for use at public consultations/meetings; 2. Complete detailed designs to include specification of boardwalks and/or platforms; 3. Carry out re-profiling works and construction works, ideally, during winter when visitor numbers are lower and disturbance to breeding birds will be minimal; 4. Create areas of marginal vegetation around boardwalks and platforms using the methods discussed earlier; and 5. Create information boards and interpretation boards giving details of natural history features and historical information about the pond and common. Improvements to the SuDs System 3.25 One of the main inflows to the site is treated via a linear ditch that contains Common Reed Phragmites australis at both the start and end of the ditch. At present it is likely that the residency time of water flowing through the ditch is relatively short resulting in poor conditions for reeds and marginal vegetation. 3.26 During the visit, plans to create a series of steps along the length of the ditch were discussed. This is an ideal way to increase the residency time of the water in the system but care should be taken as this is one of the main sources of water into the pond. At present the system does have some functionality and is an attractive part of the site. Increasing the amount of marginal vegetation at the Common Trustees Page 6 July 2012
base of the system would hopefully increase the amount of treatment without decreasing the amount of water reaching the pond. 3.27 WWT Consulting would propose maintaining the treatment system in its current state and testing the water inputs and outputs to fully assess its functionality before any major changes are made. In the future sedimentation could become a problem and it may be necessary to add a sediment trap into this feature, this would be an easier option than having to de-silt the pond should sedimentation become a problem. 4. CONCLUSIONS/DISCUSSION 4.1 Figure 2, Appendix II, shows a simple concept plan for the site that forms the basis of the costs given in Table 1. For the benefit of the costing it is assumed that re-profiling will take place in both locations with two areas of boardwalk and a platform introduced. Where possible, prices per metre or per area have been given to allow for scaling of any developments. 4.2 Fencing of marginal areas has been identified as one of the key features of any restoration. The recommended product is called Gameflex and can be purchased from Collins Nets (www.collinnsnets.co.uk). This is best secured using metal pins as outlined in Table 1. This is a black coloured plastic mesh that has been successfully used at WWT sites. It is recommended that areas of vegetation are fenced on all sides to prevent grazing. 4.3 WWT Consulting can provide site supervision for all stages of the restoration/development plans and a program of site visits can be agreed should development take place. 4.4 Construction costs are difficult to estimate at this stage as quotes are usually requested once a detailed design has been completed. Should detailed design be carried out, WWT Consulting can recommend a number of potential contractors suitable for the boardwalk and platform construction. It is understood that re-profiling work would be likely to be carried out by a contractor known to the Common Trustees. 4.5 All of the estimated costs supplied are subject to change. Should detailed design or further consulting services be required then WWT Consulting would look to produce detailed quotes to specific packages of work as outlined by the Common Trustees. The costs presented here are inflated by the assumption that a long stretch of boardwalk is introduced and also that coir rolls are employed to create the areas of marginal vegetation. A reduction in the length of the boardwalk or coir rolls used would reduce the overall cost. Common Trustees Page 7 July 2012
Table 1 Estimated costs for design and restoration of Prickend Pond, Description of Service or Product WWT Consulting Design and Consultation Costs WWT Consulting cost for concept plan development and production of materials for public consultation WWT Consulting cost for detailed design of re-profiled areas, boardwalks and platform, along with a planting plan for marginal areas WWT Consulting cost for site supervision during construction (cost per visit) Material Costs for Restoration/Improvements Unit Cost Estimated Total Cost N/A 1,170 N/A 2,325 Coir rolls 93 per metre 13,206 Fencing to protect plants - Orange Barrier Fencing Alternative fencing to protect plants - Gameflex Netting 500 1mx50m = 25 115 1mx100m = 55 128 Fencing pins 2 per pin 200 Plants 60p per plant 1,296 Boardwalk 100-200 per metre 19,500 Platform N/A 10,000 Interpretation Boards Construction Costs Total Costs for Consultation and Materials approx 800 per board 1,600 49,925 Notes These are estimated costs - full detailed quotes would be provided prior to any work commencing These are estimated costs - full detailed quotes would be provided prior to any work commencing These are estimated costs - full detailed quotes would be provided prior to any work commencing Total cost based on coir rolls being used to surround the island and along the southern edge of the pond to create areas for back- filling. Alternative methods could be used such as the log enclosures already employed Assumed fencing perimeter of 230m to fence the area along the south bank and also around the island. This is the orange barrier fencing which is slightly cheaper but is rather unsightly Assumed fencing perimeter of 230m to fence the area along the south bank and also around the island. This is the black barrier fencing which is slightly more expensive but is less obtrusive Assumed a pin every 2m to hold the fence in position, more may be required (or fewer). Metal pins are the most expensive but are recommended as they are durable and can be reused for multiple purposes Assumed planting density of 6 plants per m 2. Assumed that a length of boardwalk is used in the re-profiled area and along the southern edge of the pond. Cost based on a pond dipping platform installed at a school. Includes an estimate of construction costs This is an average cost for a board. The final amount can vary quite alot depending on materials used and styles. Detailed quotes would be provided during the detailed design phase No costs have been provided as Common Trustees have a contact for this work. Details of recommended contractors can be supplied should specialist or alternative contractors be required Assumed that Gameflex fencing has been used Common Trustees Page 8 July 2012
APPENDIX I. Photographs Common Trustees Page 9 July 2012
Photograph 1 Example of bird feeding witnessed during the site visit Photograph 2 Low water levels at the pond from earlier this year (southern bank) Common Trustees Page 10 July 2012
Photograph 3 Low water levels at the pond from earlier this year (High Street end) Photograph 4 Outflow from the pond Common Trustees Page 11 July 2012
Photograph 5 Eroding pond edge Common Trustees Page 12 July 2012
APPENDIX II. Figures Common Trustees Page 13 July 2012
Figure 1 Map of features and constraints at Prickend Pond, Common Trustees Page 14 July 2012
Figure 2 Possible development options for Prickend Pond, Common Trustees Page 15 July 2012