HIRA Report August 2004 - Sea Defences

- Fri 23rd Jul 2004

Sea Defences Work Explained to Large Audience

Over forty people turned out last month to hear presentations by John O’Flynn (Environment Agency) and Lee Fairclough (Havant BC), on the work for which their organisations are responsible to prevent flooding on the Island, in the event of unexpected high tides and storm conditions at some time in the future.

The flood defence work, the responsibility of the Environment Agency, relates to overtopping of the defences in the harbours and the storm erosion works; the responsibility of HBC relates to the southern coast of the Island.

John explained the concept of the 1 in 20, 50, 100 or 200 year events as being indicators of how robust the defences have to be to protect against those combinations of tide height, wind strength and direction and low atmospheric pressure that could give rise to those rare events.

He commented that historic records seem to indicate that the tidal rise was about 2 mm per year but this figure did not possess a high degree of certainty due to the lack of very accurate data on which to base it. To allow for the effects of ‘global warming’, people were now working on the basis of as much as 6mm per year.

Current designs are working towards levels of protection up to 50 years ahead (a rise of 300 mm, 1 ft.) and the 1:200 year event. Such an event, if it occurred, would be expected to last for two or three high tides, i.e. a period of about 24 hours and so it would not necessarily cover the duration of a single high tide event. Allowance will be made to increase heights if current sea level rise predictions are exceeded.

To allow for this degree of protection around the Eastoke peninsula, where work is expected to start next month and finish in the spring, the overtopping protection on the walls will require rises in current sea wall height averaging between 30 and 60 cm. Some points will be higher, depending on the condition of the individual sections as they now exist.

The main problem is to protect those properties that have gardens fronting the water. Up to 2 metres of garden may be lost and the walls will consist of steel piles fronted by rock slopes to break up the wave energy. The possibility of incorporating a footpath along the top of the bank was discounted, as it was not within the remit of the Environment Agency to deal with such matters. This would not of course prevent people from walking along the beach, when the tide is out, as is presently the case.

While English Nature are still putting conditions on all these works, e.g. not allowing significant encroachment onto the foreshore, their insistence on like for like replacement of foreshore used for such works is now apparently not being enforced. This should be good for the arguments about not repairing the sides of the Billy Trail, on the West coast of the Island.

Recapping the main outcome of the presentation:

Work is about to start on the Eastoke scheme, (est. cost £1.6M

The Selsmore/Mengham design is being finalised and should be finished in 2/3 years,(est. cost £1.3M

The Northney scheme discussions are now starting.(est. cost £1.2M)


After a break for coffee and some very nice cakes, Lee Fairclough of HBC talked about the South coast of the Island.

He described the considerations that had been given to the various options. He explained why the present scheme was the preferred option on the basis of longevity of effectiveness, least damage to the environment and retention of the essential nature of the sea front ambience. The main emphasis was now on improvements in the effectiveness of the defences in the area of the Nature reserve and whether to extend the use of rock groins. The idea of offshore rock islands is considered undesirable because they would be much too obtrusive with the high tidal range existing locally.

He had been of the opinion that rock groins were unpopular but several comments from the audience countered this view, pointing out the way they provided safe havens and were always occupied by groups sitting in the voids they provide. He said these comments somewhat changed his view of their acceptability.

Essentially the present method of replenishment by reuse of land drifted material, dredgings from the harbour entrance and new material when possible, would continue. There was a comment from the audience that the materials used were not entirely effective and this was confirmed by Lee. It was agreed that a larger particle size (e.g. cobbles) was preferable but that these were hard to obtain. It was the intention to use more appropriately sized material and to put in rather larger quantities on the next major replenishment exercise.

On discussions on improving the sandiness of the beach, it was agreed that this was a difficult problem. I still feel that if a stable section of beach were selected, it would be worth the experiment of improving a few hundred metres and monitoring the effects.

At the end of the meeting most topics raised by the audience had been dealt with and those present now understand the various issues better.

HIRA would like to thank John and Lee for their presentations and for giving up their time for the benefit of Islanders.

Waste Disposal

About a year ago I visited the re-cycling plant in Portsmouth. Last month I visited the first of the new ‘Energy from Waste’ plants being built to solve the waste problems of the County. Energy from waste means a big incinerator that generates a small amount of electricity.

The recycling plant takes all the ‘green bin’ waste and mechanically and manually sorts that into re-useable paper, steel and aluminium cans etc and other waste which has no recoverable value.

Up until now that residue has gone into landfill as has all the normal household waste resulting from the weekly collections. At Chineham (Basingstoke) which is the first plant to operate (the other two at Portsmouth and Marchwood, coming on stream later this year) all the residual waste from the sorting process and the normal domestic waste will be burnt and only the final residue will be landfill.

All landfill sites, bar one, in Hampshire will be closed and we will finally have a coherent waste disposal process.

Many people have been concerned about the fact that incinerators are being re-introduced, but the process is now as clean as it is possible to be. Apart from ‘lighting the fire’, no additional fuel is used, all the fuel input being the waste. The waste is loaded into the grate and dries out as it approaches the combustion zone. Combustion takes place at very high temperatures, thus eliminating the undesirable contents of the waste.

The flue gas is then washed with lime milk to neutralise all the acidic elements of combustion of plastics, for example, and the cooler gas (150 degree C) is then passed through fabric filters to remove all particles greater that 10 microns. The final output is then passed up a large chimney to the air. This output meets all environmental standards for emission.

All the waste is dried and separated (steel and glass) and the residue is land-fill or, in future, probably used as building aggregate for roads etc.

I believe this will solve our waste problems and eliminate the horror of large landfill sites, as far as domestic waste is concerned. As people will see from the press recently, other aspects of waste disposal are likely to prove far more worrying in the future.

Summer Holidays

The HIRA Committee does not meet in August, so our next meeting will be on September 14th. Our next public meeting will be the AGM in October. We expect to have a stall at the Carnival and at the Church Fete and would be pleased to see existing and potential members. We also hope to collect subscriptions during part of the intervening period. Have a good summer holiday.

Tony Higham.

Main contacts:

Chairman: Paul Fisher 92461412

Membership: Fred Gibson 92466995

Notice Board: Lois Neale 92469339

Reporter: Tony Higham 92464723.

By forum user, PaulFisher