Title: Fax Letter & Memo Wizard
Author: SLGREEN
Company: CIS Environment Agency

Jenny Barker
Cherwell District Council
Planning & Development Services
Bodicote House 
Bodicote
Banbury
OX15 4AA

Our ref:	WA/2011/109125/01-L01
Your ref:	10/01780/HYBRID

Date:		25 February 2011

Dear Ms Barker

NORTH WEST BICESTER ECO TOWN – EXEMPLAR PHASE

Thank you for your letter of consultation on this application. 

Our comments are focused on the following areas:

•	Water cycle study including water supply and foul drainage
•	Flood risk including surface water drainage
•	Biodiversity
•	Waste management
•	Contaminated land and groundwater quality

Environment Agency position

We object to this application as it fails to meet the requirements of the Eco-Town Planning Policy Statement (supplement to PPS1) and other relevant environmental planning policy.

Our reasons for this objection are outlined in detail below.  I have also included comments on elements of the scheme we are supportive of and as an appendix,        I have highlighted some minor errors within some of the submitted reports.  

It should be noted that our concerns may be overcome through revisions to the development and further information being provided.  

Water Cycle Study (WCS)
The submitted WCS is a good outline investigation.  To fully demonstrate the likely impact the exemplar development may have on the water environment, certain elements of the study need to be expanded. 

Water supply
We support the proposal to limit potable water use to 80 litres, per person, per day through the use of water efficient devices and rainwater harvesting.  This would ensure the development meets level 5 of the Code for Sustainable Homes.  We support this commitment.   

Foul drainage
The foul drainage for the exemplar site will connect to the existing Bicester sewage treatment works.  The study concludes that capacity at the works is sufficient for the exemplar but the network is likely to require upgrading and a proposal has been outlined to identify what would be required.  It is essential that a development phasing arrangement is agreed to ensure that the upgrades are implemented prior to, or in line with the development to avoid pollution.  There should be no occupation of the homes until the necessary upgrades are in place.  

Including water efficient devices within the development will reduce the volume of water going to the sewer network.  However, we recommend a margin of error is built in to the network so there is no risk of overloading in the future by any changes that may be made within the houses.  

Water quality
The Eco-town development must not result in deterioration in water quality and should take steps to ensure water quality is improved.  Further work is required on this element to ensure the likely impacts of the development is fully understood and there is confidence that it is feasible to address them.  

The process of intercepting rainfall has the potential to reduce the flow in local ditches, streams and rivers in and around the site.  We are concerned that this could lead to deterioration in the status of the waterbody this site falls within which would be contrary to the objectives of the Water Framework Directive. 

We supplied Hyder Consulting with details of the two waterbodies this site would have an impact upon, along with data on water quality in the area.  We advised Hyder in September 2010 that the Water Cycle Study should consider the potential deterioration in biology and water quality.  

In addition, there should be an outline of the steps that will be taken towards water neutrality.  This is where the total water use following development is no greater than that before development.  There is currently insufficient detail to show how this development can contribute to this aspiration.  

Recommendation : Further information is required to address our concerns to ensure the development meets the requirements of Eco-town Policy ET 17.  

In addition to considering the exemplar development, the WCS also refers to options for the Masterplan.  At this point we would like to outline our support for the options the developer is considering for foul drainage.  Nutrients are a significant issue and we would like to see an option(s) that will work towards reducing nutrient loading to the local watercourses. In particular we support the option of a small works on site discharging to balancing ponds to account for effluent polishing.

It is also encouraging to see that the exemplar site will connect to the same sewerage infrastructure as the rest of the Eco-town once it is built.

Flood risk & surface water drainage

Fluvial flood risk
A fluvial flood model has also been submitted with the application and has been used to inform the Flood Risk Assessment (FRA).   We have reviewed the model and while there are no significant issues with it, we do require some further explanation as to how the hydrology used within the model has influenced the outputs. 

Recommendation : Further information is required to support the fluvial model conclusions in order to ensure the baseline flood risk can be confirmed. 

Without prejudice to any further comments we may need to make pending the final outcome of the model review, we are supportive of the FRA objectives which identifies that all development will located in Flood Zone 1 (low risk) and therefore the risk of fluvial flooding will not be increased.  

As a precautionary measure, we recommend that the internal floor levels of all buildings are set no lower than 300mm above the 1 in 100 year climate change flood level.  This will ensure the development is resilient to any future changes in flood risk.  It is not clear from the details of the application whether this is feasible within the current design parameters of the development. 

Surface water drainage
It is proposed that surface water will discharge via soakaway wherever feasible and the remaining runoff managed through attenuation features with a controlled discharge to local watercourses. 

We welcome the commitment within the drainage strategy to limit surface water discharges from the site to the Greenfield runoff rate of 40 l/s for all rainfall events up to and including the 1 in 100 year (including a 30% allowance for climate change).

Both the FRA and the drainage strategy (including Appendix F of the drainage strategy) have concluded that a certain number of properties will be able to drain via soakaway.  However, there have been only 3 drainage tests carried out and these conclude (in Appendix C of the FRA) that there is variable infiltration potential across the site.   We are concerned that the size of the attenuation features relies on those property numbers being drained by soakaway but there is no clear explanation or evidence to show that level of soakaway is feasible.  If the required volume of storage needs to be increased, the size of the attenuation features may need to increase and we are concerned that there will not be sufficient space to allow this within the current layout. 

Although the proposed discharge rate is to be limited to Greenfield rates, Section 3.2.7 of the drainage strategy states that the overall volume of water being discharged from the site will increase as a result of the development (i.e. more water will be discharged from the site than existing but spread over a longer period of time), a volume has not be stated.  This presents a risk of increasing flooding downstream, particularly at the confluence of the River Bure (to which the site will discharge), the Pingle Stream and Langford Brook.  

Any increase in the rate or volume of water leaving the site should be avoided or mitigated on site through storage, re-use and infiltration.

The roadside soakaways and those serving properties have only been designed to accommodate a 1 in 10 year storm.   While this is in accordance with part H of Building Regulations it does not adhere to the best practice guidance of PPS25 that indicates any above ground flooding should be avoided for events up to the 1 in 30 year return period.  Designing to a minimum of 1 in 30 year standard reduces the risk of flooding, manages rainfall at source and increases groundwater recharge.  It must also be demonstrated how surface water will be safely contained or managed for these parts of the site up to the 1 in 100 year storm event (including a 30% allowance for climate change).  We note overland flow paths have been shown in Appendix A for more extreme events in excess of the 1 in 100 year event.

Recommendation : There is currently insufficient information to demonstrate that surface water can be safely managed on site without increasing flood risk elsewhere.  Further details are required to address our concerns to ensure the development meets the requirements of Eco-town Policy ET 17 and PPS25. 

Sustainable Drainage (SuDS)
We are very disappointed to see the inclusion of sub-surface attenuation in the form of tanks as part of the design.   This is referred to in the drainage strategy and flood risk assessment (including Appendix F) and on Drawing 8013-UA001881-UP23D-01 on Page 142 of the Design and Access statement.  

Although tanks will attenuate surface water, they do not deliver any further benefits that other SuDS features can - including ground-water recharge, water quality improvement, habitat creation and amenity value. They also have the disadvantage of traditional drainage systems as they are below ground, which can lead to maintenance difficulties and hide any potential blockages and failures within the system.  We would not wish, or expect, to see tanks within the drainage system of an exemplar environmental development on a greenfield site of this size and would like to see them replaced.  
 
We also note the proposal, shown on Page 139 of the Design and Access Statement includes decking and walkways over a number of the SuDs ponds. This also can hinder maintenance through the accumulation of litter, debris and silt.  We advise that access to the ponds be limited to the edge so not to obstruct maintenance access.  
 
Drawing 7163 01 shows overly large headwalls on the SuDs ponds.   This seems unnecessary over engineering which again will detract from the environmental quality these features can deliver.  

Recommendation : Some elements of the drainage scheme are not compatible with the high environmental credentials this development aims to meet.  A revised design should be submitted to show how this development follows the best practice guidelines of PPS25.  

Ground Water flooding
Section 2.4.3 of the FRA identifies that parts of the site may be at high risk from groundwater flooding and that mitigation measures will be required to manage this risk.   However, it does not identify which parts of the developments will be at risk, quantify the level of risk or detail the mitigation required beyond generic examples. 
 
Without understanding and mitigating this risk the development could be susceptible to prolonged periods of flooding.  Any mitigation must be designed with consideration of other environmental factors such as avoiding surface water and fluvial flood risk, and not depleting groundwater levels.   
 
The conclusion of the FRA, at Section 5.1, is misleading as it states the risk from groundwater flooding is low, this is only the case if suitable mitigation is provided. 

Recommendation : Further information should be submitted to show how the development can avoid the risk of groundwater flooding as required by Eco-town Policy ET 18 and PPS25. 

Bridges – flood risk
Drawing 7153 01 shows a design for the proposed watercourse crossings.  To ensure no obstruction to the flow of the watercourse and maintain a natural watercourse corridor we would wish to see bridges on this site be of clear span design and not culverted as shown on the plan. 

The culvert is shown to be undersized, impinging on the natural banks of the watercourse.  This will restrict flows on the watercourse especially during flood events, increasing flood risk upstream. The large heavily engineered headwalls also reduce the aesthetic value of the watercourse corridor through what is meant to be an environmentally sensitive development.  
 
The erection of flow control structures or any culverting of a watercourse requires the prior written approval of the Environment Agency under s.23 of the Land Drainage Act 1991 or s.109 of the Water Resources Act 1991.  As we have concerns with the current design, we may refuse this consent. 

Recommendation : A revised design should be submitted to address our concerns to ensure there is no increase in flood risk as required by Eco-town Policy ET 18.  

Biodiversity
The assessment of risks to nature conservation are inadequate by virtue of being incomplete and the mitigation measures do not ensure the achievement of net biodiversity gain.
 
In addition to Eco-town policy requirement to achieve a net biodiversity gain, PPS9 requires that planning decisions should be based on up to date information about the environmental characteristics of their areas, including biodiversity resources.

Although there has been a significant range of ecological surveys to support the development, a number of these were completed too late to substantially influence the design of the scheme. Critically, wintering bird surveys were not undertaken prior to the submission of this application, and given the nature and characteristics of the site (open farmland) it is highly likely that the wintering bird community forms an important part of the biodiversity interest of the exemplar site and wider masterplan area. 
The results of the wintering bird survey must therefore be integral to the assessment of the impacts on the local biodiversity resource, and also to the appropriate design of mitigation measures, and is therefore pertinent to support the overall conclusion of net biodiversity gain. 
 
In addition, there is no clear balance sheet of biodiversity losses and gains which allows for an informed judgement as to whether a ‘net biodiversity gain’ is indeed being provided.  

Given the loss of substantial areas of farmland, and the inability to provide compensation for those species which are dependent on open landscapes within the development, the Biodiversity Strategy emphasises the importance of the hedgerow network and the stream corridors in mitigating impacts and in achieving net gain. 
However, although there are some additional water features proposed in the stream corridors, linked to the SUDs scheme, these are not of a scale which is likely to provide significant enhancement for biodiversity, especially as the extent to which these are likely to be ephemeral, semi-permanent or permanent wet features is very unclear. 

The context of these wet features includes proposals for wet grassland, herb-rich grassland and tree-planting, but there is no clarity on how the right hydrological conditions for wet grassland are to be secured, and how the achievement of biodiversity gain is to be realised given the high proportion of the green space which appears to be accessible to residents for amenity purposes and therefore subject to disturbance. 

The area of proposed wet grassland in the stream corridor of the Bure tributary also shows an orchard, which is incompatible with wet grassland, emphasising concerns that the mitigation and enhancement is not thoroughly thought through, nor secure. 

The use of underground storage tanks as part of the SUDs network also reduces the scope for it to provide multiple benefits, and the design of extensive decking over storage ponds further reduces their biodiversity value.

Without a more robust design of a mosaic of wet features in the stream corridor, carefully designed to allow some access but with areas which are less permeable to people and are therefore less disturbed, it is not clear how the stated claim for net biodiversity gain can be secured in the Exemplar site.  The achievement of this net gain is also predicated in the Biodiversity Strategy on the future management of the habitats to be established, but although the Strategy sets out options to achieve this management, none of this has been secured nor demonstrated to be viable. 

Recommendation : the development should be re-designed to show how biodiversity will be protected and enhanced and to ensure a robust mechanism for achieving biodiversity net gain for the whole development can be delivered as required by Eco-town Planning Policy ET 16 and PPS9.   The applicant should provide a more convincing rationale for demonstrating that there is a commitment and a means to ensuring the right management is to be funded and achieved.
  
Development close to watercourses
An adequate buffer between the development and watercourse is essential to support biodiversity and link spaces to allow wildlife to move between suitable habitats.   

The buffer between the watercourse and the exemplar development is currently shown to be inadequate.
 
The stream corridors in the Exemplar site are an essential component in the Biodiversity Strategy for securing net biodiversity gain.  They have also been identified as being of particular importance for bats (and contain active badger setts). The current design shows built development, a NEAP and access routes in close proximity to the Bure which all serve to reduce the potential for the stream corridor to achieve the objective of net biodiversity gain. 

The development claims 40% GI, with 20.5% claimed as ‘enhancement’ to provide biodiversity net gain, which in principle we support.  However, the design does not demonstrate an imaginative use of the stream corridor to provide the multiple benefits of GI to biodiversity, flood risk management and amenity which will allow all these objectives to be achieved successfully.  This is due in part to the relatively constrained size of the river corridors which show substantial permeability for amenity and access routes. This is compounded by the narrow buffers provided to the other linear features on site, the hedgerows, which puts greater emphasis on the stream corridors in providing the stated net improvement. 

Of particular concern is the requirement for the stream corridor to provide a dark foraging and transit route for bats – although this is acknowledged as an important design element, the proximity of the development and the lack of clarity in the lighting strategy as to whether access routes through and across the corridor may be lit, provides no confidence that this objective can be achieved. 

Recommendation : A revised scheme should be submitted to allow for a more supportive environment for wildlife which contributes to a net biodiversity gain as required by Eco-town Policy ET 14 and ET 16 and PPS9.  

Bridge design - biodiversity
Culverting of the River Bure will have a damaging impact on nature conservation and landscape, in particular it deteriorates the river and bankside habitat while interrupting the wildlife corridor.  In certain cases on small watercourses appropriately sized culverts may be the only reasonable option, but the River Bure corridor in the exemplar site is an incised valley which is also a key component of the GI and critical to the achievement of biodiversity gain.  

The current proposal for a box culvert with concrete wingwalls and earth embankments severs this corridor, compromising its value for wildlife movement in general and in particular disrupting the flight path corridor for bats, an attribute recognised as important by the developers. The current design also detracts significantly from the natural landscape characteristics of the stream corridor. 

Recommendation : The culverts should be replaced by a clear span bridge which allows the integrity of the river corridor to be maintained to enhance local biodiversity, and with appropriately designed lighting to ensure a dark flight path is maintained below it for bats as required by Eco-town Policy ET 16 and PPS9.  

Waste
We support the use of a Site Waste Management Plan (SWMP) linked to a Sustainable Resource Management Plan and the high recycling targets outlined. 
We accept that some materials may need to be placed in landfill, provided that this is the best environmental option. 

For the masterplan, we would like to see the initiatives outlined within Section 16.5.2 of the Environmental Statement, including a re-use centre and community projects investigated in more depth. 

Contaminated land & Groundwater quality
We agree with the indication that levels of contamination on the exemplar site are low and therefore unlikely to impact groundwater quality.  However, section 3.2 of the Interpretative report it states:
Furthermore boreholes BH1 and BH5 have been installed with groundwater and gas monitoring standpipes and an ongoing programme of monitoring is currently taking place over a three month period to allow the groundwater and gas levels to stabilise and to be recorded over a range of (short-term) climatic variations.
The full results of the gas and groundwater monitoring will be issued as a separate addendum to this interpretative report.
Section 6.4 of the same report concludes that no remedial action is required.  However, it is not clear how this conclusion is reached because no results for water analysis are included within that report. The interpretative report refers to a Factual Report which perhaps includes some groundwater quality data which has not been included within the application documents. 
This is particularly relevant because of the proposal to drain surface water via soakaway.  We would not want to see any infiltration through contaminated soils as this would present an unacceptable risk to groundwater quality.  The developer will need to demonstrate that this risk does not exist.  

Recommendation : the results of ongoing investigations should be submitted for consideration alongside the Factual Report referred to in the application.  
Yours sincerely

Sarah Green
Planning Liaison Technical Specialist

Direct dial 01491 828485
Direct fax 01491 834703
Direct e-mail sarah.green@environment-agency.gov.uk

cc Barton Willmore

Appendix 1
While carrying out our review of the application supporting documents, we noticed some minor errors which we recommend are revised for reasons of clarity. 
Water Cycle Study section 1.6 – current funding
This section is out of date – the current AMP period is AMP5.  PR09 funding has been determined.  Final determination summaries are available on the Ofwat website – though it is unlikely to be detailed enough to enable any definitive statements in the WCS.
 
Water Cycle Study Section 2.2 - Study Area
Consistency with watercourse names is needed, e.g. page 11&12 Pingle Stream\Pringle Brook
 
Water Cycle Study Section 4.4.2 - Drainage Areas
Point 3 contains an error. The Gagle Brook discharges into the Langford Brook and not the Bure.
    
Water Cycle Study Section 4.6.1 – Water Resources page 30 CAMS 
“No Water Available” does not mean that drought is prevalent nor does it mean that new licences will not be granted. The definition of “No water available “in the CAMS is as follows:
 
“No water available at low flows, although water may be available at higher flows with appropriate restrictions.” 
 
Therefore it is possible that new abstraction licences will be granted albeit these abstraction licences will be restricted in their use of water at times of low flows. This generally means that the licence will specify a flow level at which time the abstraction must cease until flows have recovered. However this probably does mean that water supply for the Ecotown cannot be supplied by new surface water abstractions in the local area as demand for drinking water does not cease at low flow conditions, which would therefore lead to supply deficits at times of low flows.
 
We have been working to update the CAMS for this area and propose to have a new licensing strategy available in 2012. Currently the update is not suggesting that the situation has significantly changed in this area.
 
Water Cycle Study - Local abstractions 
Those shown within the WCS are incorrect.  One has been revoked and the other deregulated.

Our records of abstractions in the area are detailed below: 

Holder | Licence number | NGR | Source type | Use | Max daily (m^3) | Max annual (m^3) | Period of use
CF Hilsdon, Manor Fm | 28/39/14/102 | 452700 225200 | Groundwater | General farming / domestic | 20 | 7,319 | All year
WV Malins, Hawkwell Fm | 28/39/14/348 | 457400 224200 | Groundwater | General farming / domestic | 48 | 17,520 | All year
J Hunter, Watergate Fm | 28/39/14/0048 | 457700 226700 | Groundwater | General farming / domestic | 24 | 8,901 | All year

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