A short while ago Land East Of Horndean (LEOH) was given Outline Planning Permission. This is not full permission for a developer to go ahead and build, but only approves the principal of the number of houses, the housing density and the access points with a lot more information to be provided.
One of the areas that is of significant importance on the development that will need a lot more robust survey and analysis is the concerns from Portsmouth Water to ensure the development can be safely designed and built without affecting the public water supply.
The outline planning permission has a number of conditions attached to it, several of which require very significant works by the developer to satisfy Portsmouth Water, the EA and EHDC that the works can be carried out, and very simply if they can not, then detailed approval will not be given.
To find out more about the issues and how they might be resolved I contacted Portsmouth Water and spoke to Tracey Viney, the Environment and Biodiversity Specialist, who very kindly agreed to set aside some time to discuss this in more detail and explain the issues.
Why were Portsmouth Water concerned about the development of LEOH?
Essentially there are three reasons:
- Bechsteins Bats
- Footpaths and Access
- Water Supply.
Bechsteins Bat.
This is an endangered species and Wikipedia advises that there are thought to be about 1,000 in the UK. Surveys undertaken by a number of developers in the area have confirmed that Bechsteins bats are present in a number of woodlands around Horndean and Rowlands Castle, including at the LEOH site. The bats are protected by European law and any developer needs to demonstrate that the development will not impact the population. If not, the development cannot be permitted.
There is a strategic issue here. Portsmouth Water have plans for the Havant Thicket Reservoir which is a long term and very important future water supply site which could also support the needs of adjacent water companies like Southern Water (who are currently considering desalination plants as an option). As Portsmouth Water have considered the plans for the reservoir over the last years this has included their own significant research and study into Bechsteins bats and other ecology.
At the moment there is no evidence of a maternity bat roost on the site planned for the reservoir, but they do use the site, and the risk is the displacement of the bats due to construction work, moving them onto the planned reservoir location, potentially affecting Portsmouth Waters plans.
The LEOH development removes very few trees, and none of these affect known Bechsteins bat roosts but the detailed application will need to show more information on where the bats roosts are, their feeding / commuting areas, and that sufficient open space has been set aside to protect these areas so their habitat remains sustainable. This also includes conditions such as no flood lighting which might deter the bats. The good news is that the result of this is more public open space (about 21 Hectares or 50 acres on the site in all).
You may recall the LEOH application was delayed while further studies were carried out. This gave time for a specialist consultant to capture bats, fit a radio transmitter on the bat with a glue (that drops off after a few days) and track where the bat travels. This identifies the roosts, feeding areas and flight paths. Essentially this data was then used to design in zones of no development to be left around the remaining woodland. The final report that is submitted with the detailed applications needs to show this has been fully designed in and works as a overall strategic approach to the area to ensure that Bechsteins bats are not displaced.
Footpaths
The Havant Thicket Project is not just a water resource, it will provide a community recreational facility with access for clubs to undertake sail and canoe training, fishing, bird watching hides, cycle paths, footpaths and public parking with an information centre.
To optimise the green infrastructure opportunity the reservoir development could provide there must be good public access to Horndean. Therefore the opportunity to provide improved linkage from the existing woodland and excellent path network at Havant Thicket / Staunton Country Park via LEOH should not be missed.
Over the next 12 to 24 months the final layout of the housing and roads will develop and this will introduce opportunities to plan in a network of public accesses which will join up with Horndean, the SDNP and also tie in with the existing bridge over the motorway which will connect LEOH with Cowplain.
Water Supply
This is the important one and to explain the concerns we need to understand a little about the geology of the area, how water travels through the ground and is collected by Portsmouth Water, and the control measures that would be required.
Part of the land at LEOH is clay and part is chalk. The clay is pretty impermeable and where it is thick enough caps the aquifer very well. The chalk can act as an exceptionally good filter for water as it makes its way through the ground and water from Buster Hill that fell as rain tens of years ago is only now arriving at the Havant Springs. This is a natural resource area where good, clean water literally flows up out of the ground and is collected, treated and then made available to us all.
The drawing shows the Geological Plan where we are and the section runs through Butser Hill, Horndean and Havant Springs. You can see the area of Reading and London Clay meeting the chalk where we are in Horndean. Click on the image to enlarge.
It would be very simple to assess the risk if the geology was uniform but it is not. The layers of chalk and clay, were folded and then in part scraped away by glaciers and erosion over millions of years and this has created below ground paths (like pipeways) that allow water to flow very quickly from parts of Horndean to the springs at Havant & Bedhampton. Testing with tracing dye has shown that this can be very fast (54 hours). Vertical ‘Solution Features’ (we have heard the term Sink Holes used extensively) provide a number of vertical shafts to some of these pipeways. These fractures and fissures in the ground are relatively small in diameter, perhaps typically 4 to 8 inches in diameter. Where they appear at the surface the ground can be unstable.
These solution features could allow contaminants to enter the ground and get to the public water supply springs very quickly. Portsmouth Water have had experience of oil spills at Lovedean & Worlds End which have lead to the need to stop using the works. Nitrate and pesticides used in farming can also pose a risk to the public water supply.
There has been survey work on LEOH over a number of years associated with different development proposals and this has identified perhaps 30 ‘Solution Features’. Portsmouth Water are looking for these to be surrounded by a 10m diameter exclusion zone. For example, they could be designed in to form small areas of green space, locations for play equipment, grazing areas or left to grow wild.
As the plans evolve more robust survey will be required to ensure that the ground conditions are more fully understood and all solution features have been identified.
The drawing shows the location of the known ‘Solution Features’ (the coloured dots) and these will need to be properly surveyed and coordinated into the detailed plans. The area of clay and chalk can be seen on the plans.
The construction phase is also a key issue. How the foundations are built is of significant interest to Portsmouth Water, as piling operations could have an impact. It does not take a pollution incident in this sensitive area to close the springs. The simple action of drilling boreholes or piling for foundations in to the ground can cause particles to be released in to the groundwater causing turbidity. These particles can interfere with the water treatment process, slowing down the filtration process and reducing the effectiveness of disinfection. Previous drilling operations at Horndean close to junction 2 of the A3(M) have resulted in turbidity problems at the Havant & Bedhampton Springs. (Photo)
Some of the control measures will be to prohibit piling on Hazleton Farm. Parts of Pyle Farm or North of Rowlands Castle Road which are over clay are less affected by this, especially where the clay is deeper, provided the piles do not penetrate the clay in to the chalk.
The risks need to be considered not only in the construction phase (which would hopefully be well controlled) but also once occupied. The drainage for the local roads will need to go into separate pipes (storm water drainage) and pass through petrol interceptors before going into balancing ponds.
The next steps then are for the developer to agree with Postsmouth Water the additional survey work, then carry it out and then submit clear construction methodology plans which address every concern in full. If this is satisfactorily achieved then this would address the conditions for detailed planning to be granted. The main control measures for this are a presumption against building in vulnerable areas, for example within 10m of a sinkhole and a presumption against piling or any form of ground improvement (vibropiling) to prevent the water supply becoming turpid.
The detailed applications will also give further opportunity for Portsmouth Water to consider the control measures to be included as planning conditions.
The outline permission has a large number of conditions which were put forward by Portsmouth Water and the Environment Agency and which have been incorporated into the approval which must all be addressed prior to any detailed permission being given. If they are not, then EHDC will not be overruling the Water Company and the developer will need to work on their plans again to submit robust schemes which will address the risk.
Looking further forward, the proposals for the Havant Thicket Reservoir would provide a colossal water supply that would give Portsmouth Water a buffer they do not currently have and a resource that can be shared with adjacent water companies who are stretched, as well as an excellent community facility for us to use. A blog on this will be published later this week.
Good update Guy but those that read these bloggs and attended the last planning meeting will be aware of mine and that of others concerns regarding Water supply wildlife habitat and serious road usage affected by this massive concreting over of these large green and open spaces and the effect it will have on Horndean dwellers . Clearly this is Not a done deal. And I feel and sense Guy that you are now seeing what we objectors had concerns about. Like Linden Homes and the promised car parking for new yet to be ready surgery and spar shop and post office, it hasn’t happened. Will this be the same at Hazleton and Pyle Farms ? Time will shortly tell but at least HPC and EHDC have the concerns of Portsmouth Water Company to deal with , not like us mere meanies . Steve s
Hi Guy have now heard that 3 parking spaces are to be lost in the car park yet to be finished by Linden Homes, another developers promise not delivered, this car park as I said some months ago will not cope with usage for the yet to be finished new surgery, Spar and Piost Office, the entry and exit point is an accident waiting to happen and if the 700 plus school plus industrial units ever get built this car park will be gridlocked just as the Havant Rd will be. Regards Steve s
Good morning Steve, as we have debated a number of times here in the absence of a better (or least worse) location for our housing needs the next step is to make sure that the site that is developed is done so to ensure the minimum impact on the community and the best community facilities we can get. The local Councillors are putting in a lot of time and effort to look after our interests here, and have been for the last 2 years. You may not have read the article on the development panel which goes into some detail of the issues we are also looking at including biodiversity, footpaths, highways, schooling and more.
I know you dont want LEOH to happen, and have no problem with different views, but please tell us what the alternative options are on the alternative sites? Our population is growing and we are living longer. The housing increase works out at a 1.5% increase in house numbers each year. Come on Steve, either tell us what the better plan is to provide our housing needs or come on board and help us make sure the issues are addressed well for the community.
I hope to put up an article on the Gales Car Park shortly with the new proposed plans.
Guy.
Guy it’s all about doing it right, now, it’s all about getting it right for the people who are going to be affected the most, that’s what is most important, if we are having to accept this massive concreting over because you and your colleagues keep saying we need more houses based on your government facts at least get the job done correctly and stop leaving us locals to live with the fall out like Hambledon Rd Wimpey site, Clanfield, Gales Brewery , you spent most of your time pushing these developments through and then the rest of your time trying to put right what you couldn’t get right in the beginning. Don’t let any building start until everything agreed is guaranteed and then maybe you won’t waste your time and ours sorting out the failings of what the builders should have done in the first place. Steve s
Steve, local Councillors are spending a lot of time making sure the Section 106 agreement is as favourable as it can be for the community. Currently the Parish Council is looking at the community facilities we will get and what they will include. We are pressing HCC for details on the school, when it will start to be built to ensure provision is made at the right time. We are working with Solent LEP to get the best opportunities for jobs and employment for our community and residents. The combined value of the community facilities, school etc we will be getting is about £10 Million. There are several blogs on this and perhaps it is time to listen to what we will get from the new development and support us in getting it?
Hi Guy hope you had a great Christmas. Sitting here listening and reading about the north of England being flooded and wondering what it would be like, very difficult to imagine how these people, families, old people, children, animals are able to cope. I just really hope we, the planners, the council and parish workers employed for us all, for our benefit, have got it right and can 100% state that the concreting over of Hazleton and Pyle Farms will not cause flooding in the surrounding areas. I would like to bet (and I hope I loose) that the area does get flooded and water supplies to the 300,000 does get contaminated.
If the councillors and planners and developers can give us that 100% assurance it would go some way for us to accept this massive development and sleep easier but if it can’t , well there’s another story?
What do you think Guy?
Steve, the flooding in Yorkshire is truly awful. Unfortunately most of the areas affected are in flood planes where it is also very likely.
We do have areas that regularly flood – the Lavant, a below ground river that passes through Rowlands Castle does rise above ground from time to time. There are established flood plain areas where building is just not going to ever be considered. If you look at the rejected SHLAA sites you will find a load there.
I think you are getting surface water flooding and contamination of the aquifer mixed up together – the risk with the aquifer is disturbing the sinkholes.
Southern Water, Portsmouth Water and The Environment Agency are ok with development provided the developers provide extensive survey and design in the sinkholes. As I think I have said to you a few dozen times here, if they are not happy with the plans when they are submitted to discharge the planning conditions then the condition won’t be signed off.
This includes Southern Water and the surface runoff.
How is Porchester?
Don’t know , how is Porchester?
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