The improvement of Prickend Pond: a plan

Transcription

1 The improvement of Prickend Pond: a plan The Trustees of Chislehurst Commons are publishing this plan in seeking the widest possible consultation There are misunderstandings about Prickend Pond which need to be scotched. Firstly, it is not a spring-fed natural pond. It is a depression in the ground resulting from gravel digging in the early years of the 19 th century. Secondly, it is not topped up by mains water. It depends on rainwater from the drains on surrounding roads. To this extent it is little more than a large soakaway, although fortunately the water does not soak away, any loss being largely due to evaporation. Thirdly, it rarely receives any water from the slightly higher pond, alongside Ashfield Lane, Rush Pond. This too, is entirely dependent on run-off from local roads and is therefore at the mercy of the weather. It rarely reaches a level sufficient to overflow through the underground connecting pipe to Prickend Pond. The low level of both ponds is a recurrent problem. Fourthly, some of the resident wildlife is not welcome. The Trustees of the Commons pay 600 a year for control of the rats and the feral pigeons. Frustratingly, while we are spending good money on culling them for good reasons of public health, members of the public are busy feeding them. While it is entirely acceptable that small children come to feed the ducks, it is not acceptable that whole loaves are scattered on the bank and in the water by adults who ignore our pleas for restraint. They are not only encouraging the rats and the pigeons, but what is left uneaten rots and sours the water. Then there is an alien species, the Canada geese, which thwart our attempts at marginal planting and leave their messy droppings all round the banks. In 2010 we planted around 400 bur reeds, every one of which the geese gobbled up within a week. Despite these problems there is ample evidence that Prickend Pond is, in most people s eyes, the most attractive feature of the High Street and therefore the Trustees feel duty bound to do all they can to conserve and enhance it, especially as the Chislehurst Town Team, supported by the Chislehurst Society, the Commons trustees and local traders, is making valiant efforts to improve the High Street as whole. The problems The most obvious problem is the lack of water. Our records show that for many years past the summer months usually saw a substantial drop in water level. Climate change has exacerbated the problem. During this year, even the record rainfall during the spring and early summer was insufficient to keep the pond topped up once the rain abated. Concern is also expressed that the island is getting smaller. Archive photographs indicate that the island has been at its present size for at least 25 years. However, were it not being held together by the roots of the mature willow trees, erosion certainly would make it become even smaller. The particularly worrying problem is that the island is too small to allow the natural regeneration of the trees. Inevitably, the run-off from local roads is polluted with heavy metals and hydrocarbon compounds. This mix serves to enrich the water to the extent that algal blooms sometimes appear in prolonged spells of hot weather. In light of the main source of the water it is surprising that the pond is not

2 even more polluted; in fact, the water is clear, rather than turbid and is usually well oxygenated. Fortunately, little silt reaches the pond. There is not much that can be done to soften the appearance of the north bank (nearest the Queens Head) and the east side (nearest Green Lane) where there is a concrete edge and an asphalt path, so our efforts at planting may have to continue concentrating on the southern and western sides. The corner of the pond nearest to the High Street (west side) has an unsightly area of granite chippings retained by a revetment of horizontal chestnut poles. It is below this section of bank that there is the greatest unattractive exposure of gravel when the water is lowest. The predations of the rapacious geese have foiled our attempts at increasing the diversity of plant species around the pond. The one plant to defeat them so far has been flag iris (Iris pseudacorus). There are other species which may be tough enough to withstand them, which we plan to try. Our efforts aimed at stopping the wholesale dumping of bread have failed so far, but we must not give up. We are already engaged in reducing the rat and feral pigeon populations and we are studying the feasibility of culling the geese. Solutions and the plan The Trustees have based the following plan on a project carried out by students of Greenwich University and a study commissioned from the consulting arm of the Wildfowl and Wetlands Trust (WWT). The aim is to contribute to the Chislehurst Town Team s endeavour to make the High Street a vibrant and attractive place for residents, businesses and visitors by making the pond an even more interesting and popular feature than it already is. To this end our detailed proposals are as follows. The ditch Most of the water entering the pond flows down the ditch, which a few years ago we widened and planted with Common Reed (Phragmites australis), which has some effect in cleaning the water. Since we made our alterations the plant species have become more diverse and now include Purple loosestrife (Lythrum salicaria) Great willherb (Epilobium hirsutum) and Monkeyflower (Mimulus guttatus). The reeds are thriving at the two ends of the ditch, where the water is resident longest. By introducing steps or shelves at points along the ditch we would increase the residency time of the water and enable more reeds to grow. However, we would have to take care that more shelves did not impede the water flow to such an extent that the volume reaching the pond is substantially reduced. We propose that this work be done in the first year of the project, that is, in the autumn of Re-profiling the banks Making the banks along the southern and western sides slope more gently towards the water, with the new surface grassed, would have two principal advantages. Firstly the pond would be made somewhat smaller, thus taking more advantage of the available water. Secondly we would create a wet soil area suitable for marginal planting. Here we would lay pre-vegetated coir fibre rolls (rather like Swiss rolls of coconut matting planted with seedlings). The plants would be carefully selected for their likely distastefulness to the geese, for example: Flag iris (Iris pseudacorus), Common reed (Phragmites australis), Soft-rush (Juncus effusus), Lesser pond sedge (Carex acutiformis), Great pond s edge (Carex riparia) and Reed canary-grass (Phalaris arundinacea).

3 This would be a welcome diversification of plants in defiance of the voracious geese. As the coir rots, the plants take root naturally in the underlying soil. For the first one or two growing seasons, while the plants are becoming established, they would have to be protected by netting. It will be necessary to reduce the crowns of some of the pollarded willows in order to reduce their shading effect. At the western end (nearest the High Street) we would temporarily remove the seat. The tops of the two inspection pits would have to be lowered. The chestnut pole revetment would be removed and the existing bank material would be pushed into the pond. Again, the aim is to make the pond smaller, to make the incline less sharp and to create an area of wet soil for marginal planting with coir rolls. We judge that here the bank material would have to be augmented with imported top-soil before distributing grass seed. At present it is this part of the bank which attracts the most foot traffic and therefore, in order to give the grass as much protection as possible, plastic netting grass reinforcement would be laid, through which the grass would grow. We propose that the bank re-profiling, which is shown in the illustrations, be done during the autumnwinter of Newly sown areas would have to be fenced until the grass is established. The island A means of enlarging the island has been much discussed over recent years, particularly by the Chislehurst Town Centre Management Group, as well as the Commons Trustees. The logistical problem is that the water around the island is up to 1.5 metres deep and so it would take a great deal of material to build up the margins of the island. That is quite apart from the problem of getting to the island without taking the drastic action of draining the pond. A possible alternative would be to surround the island, or at least part of it, with anchored floating eco-islands. These comprise pre-vegetated coir cushions floating on plastic buoyancy tanks. Such floating islands are frequently used to encourage nest building by such birds as divers. In our context they would serve to make the island appear larger, although they would not allow the growth of trees. You will see below that we have costed the floating islands, but we do not propose to include them in our project at this stage, nor to address the problem of the island in any other way. Boardwalk A completely new and interesting feature would be a boardwalk extending above the marginal vegetation along part of the southern bank. This would be made from re-cycled plastic, a tough and durable material which gives a superficial impression of being wood. Some of the seats on the Common are made from it. It does not rot and is more resistant to vandalism than wood and has a non-slip surface. The boardwalk is shown in one of the illustrations. We propose including this work in the second year of the project. Construction would be carried out in-house.

4 Costs Prices are as quoted in August 2012 and include VAT. The ditch 4 no. untreated no. pre-vegetated reed Re-profiling the banks 2 no. days of contractor s per day 1, no. tonnes of top-soil, including delivery 1, no. kilos of grass seed 4.00 per kilo no. 2 x 20 m rolls standard grade 258 1, no. bags GrassProtecta fixing Marginal planting 123 no. metres of pre-vegetated coir per 3 metre length 1, no. 50 x 1metre rolls of mesh per roll no. road Boardwalk 33 no. metres of , plus 720 delivery 5, Contingency reserve at 10 per cent 1, Grand total 12, Floating eco islands These are made 2 metres square. With pre-vegetated coir cushions they cost each. Who would do the work and how would the project be financed? The earth-moving for the re-profiling of the banks would require the employment of a contractor. The removal of the seat and its concrete base and the alteration of the inspection pits might also require the services of a contractor. The rest of the work we envisage being carried out by our two keepers and our team of Friends of the Commons Volunteers. Some of the costs could be met from our own reserves, which largely come from the donations of our 500-plus Friends of the Commons; the rest would require external support. We are in the process of seeking funding from Fields In Trust and there may be other sources we might explore. Donations from individuals would, of course, be very welcome.

5 Other developments The long strip of ground between the asphalt path and the fence of the Queens Head garden needs additional planting in order to give greater variety and some seasonal colour. The public would appreciate more seating and there are several places which would be appropriate for the installation of seats. What has not been included in the plan? One suggestion was a tea hut on the bank nearest the High Street, presumably with tables and chairs set out on the grass. On a number of grounds this has been left out of the plan. Firstly there would be the practicalities of laying on services and providing staff for the hut. Secondly, such a facility might be unwelcome competition for the tea rooms which already exist on the High Street. But what must finally rule it out is Clause 15 of the 1888 Act of Parliament (which established the Board of Conservators and the scheme of management of the Commons) which forbids the erection of any permanent enclosures, sheds or buildings on the Commons. Another suggested addition, which was mooted in the WWT report, was a platform projecting over the water from the bank nearest to the High Street. This, it was thought, might have the effect of restricting bird feeding to that one area. The WWT report gave an estimated cost of 10,000 (which would be reduced by carrying out the construction work in-house). Our objections to the idea are that, firstly, it probably would not restrict feeding to that area. Every day we see parents and little children feeding the birds from the path alongside the Queens Head and it is unlikely that this would stop. Secondly, to some extent the proposed boardwalk compromises the appearance of naturalness which we would like to preserve and enhance; a platform would, we consider, be a step too far. Consultation The Trustees have already received comments on the WWT report. Now that we have concrete proposals we seek comment more widely. The plan will be placed on the Commons website and any other organisation is welcome to copy it on to their own website. Chislehurst Library has agreed to accept a display. The plan will be distributed to the Chislehurst Society, Chislehurst Town Team and Town Centre Management Group. Copies will be sent to our MP and ward councillors and all the traders on the High Street. The Commons information boards will, of course be used. Questions and comments can be sent via our website, or write to Trustees of Chislehurst Commons, Old Fire Station, Hawkwood Lane, Chislehurst BR7 5PW.

6 The gravel area will be grassed.

7 The end of the pond nearest the High Street as it was in September 2012 Artist s impression of how it would look Artwork by Trevor Root

8 Part of the southern side of the pond in September 2012 Artist s impression of how it would look

9 Part of the southern side of the pond nearest to Green Lane/Heathfield Lane, September 2012 Artist s impression of how it would look