Thursday, 23 August 2007

walk round 18th august - report by Andrew Leeke

Deerhurst Community Preservation (photos/ maps not attached!)

Meeting held on Saturday 18th August 2007

Present: Andrew Leeke
Brian Leeke
Ken Samuel
Will Morris
Tim Morris
Bill Phelps
Tansy Leeke

Object: Initial Analysis of Flood Defence Shortfall by reference to the attached plan provided by Tim Morris.

1. The flood defences commence at the southern end of the village, adjoining Ken Samuel’s slurry pit. In order to prevent the flood outflanking the bank and coming through Ken’s buildings, it may be necessary to extrapolate the bank in a southerly direction towards the telegraph pole in the middle of Ken’s field.
2. At points A and B there is an existing access from the lane into Ken’s buildings, which will form part of the new defence at this point. We discussed moving the existing floodgate to act as a new floodgate, but defence at points A and B will only be needed in the event of a very high flood, and Ken suggested that new stanks constructed here would only need to be of a relatively short height in order to achieve the overall protection height.
3. At point C is the floodgate into the village, which proved to have the following problems:3.1 It is woefully short of the existing flood bank height, and nowhere near the necessary raised height, which may involve an additional 0.8m.3.2. During the flood it was observed, in the centre, to have bowed inwards by at least 3”.It may well be that this gate is designed to flex. The possible solution discussed was to leave the floodgate in place where it does a perfectly adequate job in a normal nuisance flood, but to construct recesses for a bracing RSJ to be installed in the event of a large flood. Further, in the event of a large flood, the existing floodgate requires a much higher defence. This will entail the construction of new stanks behind the existing gate to receive a modern light-weight stank system up to the full height of the extended banks.

4. Between points C and D the flood bank is partly on Pippa Leeke’s garden and partly on Ken Samuel’s land. The flood bank appears perfectly sound and requires only to be raised to the new height.
5. From point D to E the bank is on Ken Samuel’s land. Ken does not want clay from elsewhere to be deposited on his land while he has clay of his own which he wants to have moved and which should be sufficient for the purpose, or part of the purpose, with the rest being made up from the clay from elsewhere. It would be best to incorporate, if possible, this requirement into the arrangement with ‘Keyway’ (or some other commercial enterprise) so that there is an integrity of construction of the whole bank by the same organisation.The bank next to the Springett’s corner is a problem area, especially as there is no access for a JCB. The bank at this point is particularly robust, however, and should not prove a problem. At point E – the flood bank passes onto Reg Ward’s land and forms the access to his house and to Peter Lord’s house. Peter Lord has expressed the intention of raising his house, and the curtilage around it, by three feet. This would mean that raising the flood bank at this point would simply match in. The opinion was expressed that it would not be possible to take a bank around Abbots’ Court and Odda’s Chapel, or to protect David Baker’s house, but this is a matter for further discussion.
6. At point F is the floodgate protecting the entrance from the west of the village. This is set up higher than the floodgate at point C, but is, nonetheless, again woefully short and the same arrangement needs to be put in place as at point C.
7. Between point F and the church is, possibly, the weakest point on the flood defence system. The village sits on sand and gravel, and, therefore, as the flood rises the pressure increases and causes seepage under the clay banks. There are no clay banks in the churchyard, and in the July flood there was both overtopping and considerable seepage between point F and the church.This is a very sensitive area, as there will be considerable opposition to disturbance of consecrated ground. A temporary flood bank was made during the flood, and this is, for the moment, simply being tidied between F and the Wellingtonia tree, but overtopping of the churchyard was taking place almost up to the church. This will have to be addressed. There are two problems. Firstly, the water has physically to be stopped from over-topping and, secondly, the seepage has, if possible, to be impeded. The options are:7.1. A clay bank to be imposed over the churchyard on the existing land.7.2 The pathway (since, hopefully, there are no graves thereunder) may be excavated to a considerable depth and backfilled with clay, and the pathway itself elevated to the new level so that it forms part of the flood bank.While acknowledging that this is sensitive area, and that the Church Authorities and English Heritage will wish to impose conditions, it is premature to consider the matter any further pending the appropriate engineering advice. There will be an engineering solution to maximise flood protection at this point and, until we know that, and how it impacts upon the churchyard, it is not right to raise the matter with the interested parties. The object of Deerhurst Community Preservation must be to achieve the best engineering solution, and this situation (the necessity to carry out works on consecrated ground) is not without precedent. At present, seepage through the churchyard is dealt with by the pumps, but in a mega flood, seepage is an issue and may overwhelm the pumps. Ways of slowing it down must be considered.
8. From the church to point G at the rear of Will Morris’ grain store is land, which, in the past, has been naturally high enough to preclude flood ingress. (We are now on Will and Tim Morris’ land, and, as can be seen from the photograph, much of this is where the water entered the village.)Between G and H is a part of the flood bank not renewed by Britannia, but constructed by Arthur Bevan using local soil. Though of poorer quality than the remainder of the banks, it did not move in the recent floods, and there will be an engineering solution for this section, principally by increasing the height and depth.
9. At point H are the pumps, and the following points arose in connection with them:9.1.There are two submersible pumps contained in the pump chamber powered from a 3-phase electricity supply. Each pump pumps 30L per second, which translates to 48,000 gallons per hour. The combined pumping of the two pumps is, therefore, considerably lower than the previous second hand colliery pump, which, in best working order, moved 70,000 gallons per hour.9.2. The pumps are submersible and in a chamber which is large enough for them to be replaced with larger pumps. We need - for the ordinary nuisance flood - a pumping capacity at least as good as we had previously, and the two pumps should, therefore, be replaced with much larger pumps (twice the size, if possible).9.3. In addition, it is quite foreseeable that a flood will coincide with a power cut and we, therefore, need a 3-phase generator to put in place during power cuts.9.4.There is a need to raise the pumps. The Environment Agency says that they continue to pump at the same rate, but it was felt that, as the flood increases in height, they are pumping against greater and greater pressure.9.5.The water arrives at the pump from the centre of the village via a piped system into an open ditch. Save as mentioned at 12 below, this was considered adequate for the purpose.
10. Between points H and I the flood bank is accessible and needs, simply, to be raised and strengthened, particularly by the Christmas trees. Point I is the present northern end of the flood defence, and water is clearly capable of outflanking it. A new bank is, therefore, needed from point I up the side of Barn Lane to the oak tree. This is Ken Samuels’ field, and both the ditch and the gate close to point H will need to be moved. A gate for a field used by cattle must be in a corner, and this is, therefore, a matter that will need to be resolved with Ken.It will also be helpful for an access to the pumps to be created at this point, so that ancillary pumps can be added when needed.
11. We discussed the water that comes down Barn Lane from higher ground. Presently, it comes down the southern side of the lane in a ditch and crosses under the road in a pipe at point I All of this needs to be enlarged, as water from Barn Lane was a problem during the last flood, and it is important to divert it before it gets into the village and causes extra pumping problems.
12. Lastly, we moved to Will and Tim’s gateway to observe that the village drain passes through a pipe between X and Y on the photograph. It passes under the field to point Z where massive pipes were installed by Britannia taking it to the open ditch and thence to the pumps. Will believes it is only the short section of the initial pipework that needs to be enlarged as, between Y and Z, the pipework is 9” and should be adequate. A few other points came up during the meeting:(A) There was water ingress into the church during the flood, albeit only in the heating wells.(B) We need a Schedule of Costs incurred, both on 22nd July and subsequently in restoration, so that this can be presented as an interim bill to the Environment Agency, Fire Brigade, or whoever.(C) Churchyard stanks – water reached 2” from the top of the extra board added by Norman MacPherson.(D) Telephone pole pipe from riverflow measuring station needs to be closed off outside village.(E) Extra manhole needs to be created outside the churchyard stanks to relieve the pressure on the manhole by David Gardner’s house.(F) Access to all parts of the banks from inside the village, where possible, should be arranged.(G) We discussed deposit of additional clay at regular intervals around the inside of the flood banks, to be used in an emergency for shoring up.(H) Bill Phelps agreed to interview villagers with a view to producing a definitive record of what happened on 22nd July 2007.

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