Mr N Lancaster                                                                Our ref:            WX/2007/104925/01-L01
East Dorset District Council                                               Your ref:            3/2007/1332
Development Control                                                         Date:               26 November 2007
Council Offices
Furzehill
Wimborne
BH21 4HN

Dear Mr Lancaster   

NEW RETAIL STORE, CAR PARK, ACCESS AND ASSOCIATED WORKS AND NEW
RIVERSIDE PARK WIMBORNE CRICKET GROUND, ROWLANDS HILL, WIMBORNE, DORSET

 Thank you for consulting the Environment Agency on the above planning application and associated Environmental Impact Assessment (EIA). 

We object to the proposed development on Biodiversity and Conservation grounds due insufficient information and consideration of the impacts of the development on the local environment. This objection is in accordance in accordance with Planning Policy Statement 9 (PPS9) and is discussed below. 

We welcome the proposed amendments to the design including the modification to create a large riverside park, and avoidance of development within the floodplain. We are pleased to see the buffer of 4m retained between the ditch and the development to the north of the site.  However, we have concerns regarding the current proposal. 

EIA - Ecology (Chapter 16)  
Chalk River BAP Habitat
The main feature of the site in terms of nature conservation, as the ecology section of the EIA states, is the River Allen and its immediate corridor. Whilst the EIA recognises this it does not sufficiently recognise the value of this habitat in the appraisal, nor in terms of mitigation and enhancement opportunities. 

The River Allen is a chalk stream and is therefore recognised as a Priority Habitat under the UK Biodiversity Action Plan. As a general obligation under the UK BAP the Environment Agency and other bodies have a number of objectives to maintain and enhance the characteristic habitats, plants and animals of chalk rivers, including winterbournes. Damaged river reaches should be restored together with water quality, flows and habitat diversity. 

The UK BAP specifically identifies the need to protect chalk rivers from inappropriate development and secure the opportunities for enhancement through development, and other land use changes. 

As the EIA states, the development will not impact directly on the river or its corridor, and that habitat enhancement measures will be undertaken as part of the site re-development. However we do not feel that the significance of in-direct impacts have been properly assessed and mitigated for. We believe that there are risks from pollution continuing post development, and the maintenance of water quality control systems is crucial to ensure continued protection (see comments re drainage). 

The habitat enhancement measures of wildflower planting and the use of bat boxes and bird boxes do not specifically relate to the obligations under PPS9 and the UK BAP to enhance key BAP habitats. Therefore the enhancement measures should be developed to include wetland creation and river enhancement works. 

Water Voles
The River Allen is part of the River Stour Core Area for water voles. This means that water vole populations within this catchment are in decline and fragmented. This core area is the most vulnerable core area in the county, and populations are very vulnerable to any works. Additionally, populations would benefit from habitat enhancements locally.

The water vole is protected under Schedule 5, Section 9 (4) of the Wildlife and Countryside Act 1981 which makes it illegal to damage, destroy or obstruct access to any structure or place a water vole uses for shelter or protection. Additionally, Water Voles are a key UK BAP species, for which the Environment Agency and other bodies are tasked with protection and enhancement. As for chalk rivers, the enhancement proposals should include be developed to include water vole habitat creation.

Otters
We disagree that the use of this section of river for otters is likely to be “occasional at best”. A recently installed camera based at Walford Mill, approximately 0.5km upstream of the development site identified otters using the Allen through Wimborne on an almost nightly basis. The 2 channels through the town provide the only route for otters moving between the Stour and the wider Allen catchment. Both rivers have excellent records indicating strong otter presence. Therefore, we expect otter usage of both channels to be regular, possibly daily. Issues such as increased lighting, disturbance and habitat enhancement should be seen as critical to facilitate passage of this legally protected species. 

Invertebrates
The data from DERC indicated the presence of white-clawed crayfish, the UK’s only native crayfish species. We know as a result of annual monitoring, and previous county-wide surveys that the River Allen throughout its length holds a stable population of native crayfish. Additionally this river is one of only 4 watercourses in the county to hold this rare and legally protected species. Historically native crayfish were present on all Dorset’s chalk streams, but their presence has dwindled significantly since the introduction of non-native American Signal crayfish, and the associated crayfish plague. 

Therefore, not only is the River Allen a nationally important chalk stream BAP habitat, it also contains one of the few remaining populations of native crayfish in the south of England. 

For these reasons, the sensitivity and impact of the river and it’s associated protected crayfish, should be increased to be adverse at a national level, and to be of moderate/major significance. 

Pollution impact on the River Allen, as suggested above, could be adverse at a national/regional level and of moderate/major significance. 

We disagree with the assessment in paragraph 16.104. The presence of native crayfish in the river may well represent a significant effect due to on-going management of surface water run-off and maintenance of the drainage infra-structure. This is a nationally significant species and the effects of a pollution incident would be moderate/major. 

Drainage and Flooding
The EIA identifies that during construction there is a potential surface water run-off pollution risk to the River Allen, and the underlying groundwater that is considered to be a moderate risk. Mitigation is proposed during construction that includes the advance use of attenuation tanks, surface water drainage trenches and silt traps. Additionally, Environment Agency guidance will be followed for Pollution Prevention. An infiltration discharge SUDS system will be used. These are all important factors that will help reduce impacts during construction on the important receptor that is the River Allen. 

However, these mitigating factors are not included within the summary table of significance, which suggests that the significance of these impacts is negligible and that mitigating measures are not necessary. We note that these measures are included in the table of significance for the completed development. 

We do not agree that the residual impacts of the effects on pollution risk to surface and ground water quality are negligible, as the use of attenuation tanks, silt traps and interceptors are only effective if they are regularly cleaned and maintained. In this case, the attenuation tanks will be below ground. Will they be accessible and will they need to be regularly maintained? Will the interceptors to be incorporated into the car park areas and service yard be regularly cleaned and maintained? We would recommend that the attenuation is kept above ground in an open SUDS system including constructed wetlands, or that a final level of ‘polishing’ is incorporated into the design that includes an open ditch and wetland system within the riverside park. This would ensure that surface water discharge is run through an additional filtration mechanism before it enters the River Allen. 

Lighting
The river corridor on the western boundary is described as being dark, with the main lighting being provided from the small retail units of Crown Mead. During construction and for the completed development, the specialist lighting assessment should ensure that there is no increase in light levels to the river corridor. As discussed in the comments for the ecology chapter, there are sensitive receptors of national importance that could be impacted from increased lighting and disturbance. This should include the very careful consideration of where boundary lighting is positioned during construction, and the deign of lighting and position in relation to the river corridor, post development.
 

Habitat Mitigation and Enhancements
We welcome the inclusion of a riverside park, and recognise that the applicant has increased the available land for this purpose. However, the landscaping proposals for this park should be more innovative and creative, focussing on opportunities to enhance the wetland interest of the site, and of the river and it’s associated legally protected species. The development should design the drainage to provide certainty in terms of pollution control through additional surface water run-off filtration, before discharge to the river, in a way the enhances the park area and increases wildlife habitat. 

This can be done in the following ways: 

1.      Re-look at the drainage plan. Are there mechanisms to reduce surface water run-off from the site e.g. the use of a green roof on the building? This would significantly reduce the volume of water to be managed through underground tanks, provide a creative opportunity to provide an interesting wildlife habitat and reduce the carbon footprint of the building. It may also contribute to the mitigation of landscaping impacts.

 

2.      Re-consider the proposal to contain attenuation in underground storage tanks. This misses an opportunity to create additional wetland habitat, and increases the risk of pollution incidents through poor management of inaccessible tanks and petrol interceptors. We would prefer to see the attenuation managed through a series of long ponds (outside of the floodplain limit of 18.2m) designed to be a significant landscape feature. Alternative drainage arrangement could reduce volumes of water requiring attenuation. This would enable proper management of the water on the site, in a sustainable way. It would also contribute towards the landscaping of the site in a very positive way and create additional flood refuge habitat for water voles. If this is not possible, the surface water discharge should be passed through an open ditch and pond system before it is discharged to the river, to provide a final ‘polishing’ effect. This would also help create some additional wetland habitat within the floodplain to support the river corridor habitat.

 

3.      Propose habitat enhancements to the currently fairly uninteresting bank of the River Allen alongside the site. Options to consider should include bank re-profiling to create better, wider wetland margins, and adjacent pond features that tie in with the surface water drainage system, and again help reduce the risk of pollutants entering the river. These features would also provide improved habitat for water voles, otters and crayfish.

 

4.      Propose habitat enhancements in-river to enhance habitat for crayfish in-particular and improve the chalk stream habitat generally. This could include some in-stream features alongside the currently hard wall of the Crown Mead shopping centre. This would provide biodiversity enhancements to crayfish, brown trout and may also help deliver some landscape enhancements.

 

5.      A construction and environment management plan must be submitted to EA and agreed before any works on site progress. This must clearly identify the sensitive ecological receptors described above and outline measures to mitigate impacts.

 

6.      Areas not to be impacted directly through the development must be clearly fenced off from contractors and machinery before any works commence on site.

 

Residual Effects.
As described above, We are concerned about the residual effect of the drainage design. How will maintenance of the attenuation tanks, petrol interceptors and oil filters be assured? The risk of failure is certainly present and the impact would be major. 

Another effect of a supermarket on site and associated waste management may mean an increase in the local brown rat population. This could have a negative effect on any remaining water vole population, and may prevent the restoration of water voles to this stretch of river. We suggest that the applicant are responsible for a sensible and on-going rat control management plan in this location.

 

Summary
The EIA has not sufficiently identified the most sensitive receptors on site, and the mitigation and enhancement proposals do not go far enough in delivering an improved scheme. 

We do not agree that the table of significance addresses all the relevant issues. Management of surface water drainage should be an on-going issue, with the consequence categorised as major adverse impact if management fails. 

Additional Comments on the EIA and Planning Documents 

Flood Risk Assessment
The final Flood Risk Assessment (FRA) includes on 'old' proposed drainage plan (Rev. A), instead of the latest proposed drainage plan (Rev. B) which has been included in Technical Appendix 13 of the ES.  We recommend the LPA request the applicant submit an updated 'final FRA' to include the correct proposed drainage plan (Rev. B).  Additionally the Micro Drainage Summary Sheets differ between the FRA and Technical Appendix 13 of the ES; again we recommend the LPA request the FRA and/or Appendix 13 be updated appropriately.

The FRA includes a plan showing the proposed drainage. We have not checked this plan in any detail but advise it be checked, especially the proposed manhole cover levels - manhole S19 has a cover level approximately 2m above existing ground level.

There are flood defence assets (which form part of the Wimborne Flood Alleviation Scheme) within the application site boundary.  The proposed development  (permanent and temporary works) must not affect our ability to access the flood defences, or the wider river corridor to carry out routine inspection and maintenance activities.  In due course, as part of the land drainage consenting process, we will require additional details of the proposed Riverside Park adjacent the River Allen.

Design and Access Statement
We note that Paragraph 5.7.1 refers to PPS24 under the Flooding title. We assume that this should refer to PPS25.
 

Sustainable Construction
We strongly recommend that the proposed development includes sustainable design and construction measures. In a sustainable building minimal natural resources and renewables are used during construction, and the efficient use of energy is achieved during subsequent use. This reduces greenhouse gas emissions and helps to limit and adapt to climate change.  Running costs of the building can also be significantly reduced. There is an ideal opportunity to maximise the use of sustainable construction and technologies in the design to minimise the impact of the development.

Water Efficiency
Water efficiency measures should be incorporated into this scheme. These should include, for example, water butts, rainwater recycling and the use of water-efficient internal appliances and systems. It would assist in conserving natural water resources and offer some contingency during times of water shortage.

 

If you are minded to approve this application prior to the submission of further information to address the issues raised above, I would ask that we are re-consulted in order that further representations can be made. 

Please contact me if you have any queries.
 

Yours Sincerely

MR MICHAEL HOLM
Planning Liaison Officer 

Direct dial 01258 ######
Direct fax 01258 ######
Direct e-mail 

cc Barton Willmore Planning Partnership

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