Biodiversity and development

As part of Wiltshire Council's ongoing efforts to improve its infrastructure to increase efficiency, minimise pollution potential and, reduce its carbon footprint, we are offering to fund the upgrade of the sewage systems of private homeowners. Wiltshire Council and Wessex Rivers Trust are collaborating to improve water quality in the Hampshire Avon catchment using a government grant.

It is thought that our many rural sewage systems may be significantly contributing to the water pollution and excess nutrients in our catchment. This is because they are simply designed to separate liquid and solid waste and release wastewater into the surrounding soil where it is 'treated' by bacteria. However, septic tanks do not remove excess nutrients from human waste and where septic tanks have either been sited in an inappropriate area, start malfunctioning, or are now being affected more by flooding, these nutrients eventually enter our precious waterways.

Excess nutrients create imbalances in our rare chalk stream ecosystems, encouraging algal growth. This leads to a damaging process called eutrophication, which starves the waters of both light and oxygen. This, in turn, is preventing the conservation of our protected sites from being achieved. Improved sewage systems have been developed and now form part of the solution of nutrient enrichment. Moreover, upgrading your septic tank now could save you difficulties when it comes to selling your property due to an Environmental Agency law that came in as of 2023 related to GOV.UK: Environment Agency - General binding rules: small sewage discharge to a surface water (opens new window).

Package Treatment Plants

Package treatment plants (PTPs) are an improved rural sewage treatment device which not only separate waste but also treat it with bacteria inside the system. More PTP systems are being designed to also remove nutrients, with the aim of releasing clear and safe water which is clean enough to discharge straight into a waterway. Moreover, there are other devices that can be fitted in series with these PTPs as tertiary treatment which produce an even better environmental standard of water quality.

There are various types of PTPs that can be used. Some use aeration to treat the waste, whilst others purely rely on their bacterial communities growing on internally rotating paddles to do the job.

Which system is recommended for your property and whether tertiary treatment can also be fitted will be determined by our third party professional consultants who will perform initial assessments.

The scheme

This initiative offers to cover 100% of the capital costs to upgrade old septic tanks and other sewage systems to newer and more efficient package treatment plants. It also offers the possibility of adding tertiary treatment if recommended (particularly if the plant drains to watercourses), to help improve the water quality of the wastewater even more. The new systems to be installed are approved and certified by British Water. All works will be in line with relevant planning and building regulations and environmental permitting.

A large benefit of entering into this scheme, apart from having the works paid for, is that the project will be managed on your behalf, saving you both time and money.

How to apply

To register interest for the scheme, residents should submit the Septic tank upgrade sign up form: Revamp your tank! (opens new window). It is important that you identify accurately where your property is located, for Wiltshire Council to determine if you are eligible for the grant. Your form will be assessed and Wiltshire Council will endeavour to inform you of the outcome within 6 weeks.

If you are accepted into the scheme, we will be in touch about the next steps.

The pre-requisites to being eligible for this scheme are:

• the property must be within the Hampshire Avon catchment and in Wiltshire
• must be close to a watercourse, connected to the Avon or one of its tributaries
• the applicant must be the homeowner or have the homeowner's permission

Revamp your tank: frequently asked questions

New developments, large and small, can have a significant effect on:

• our natural environment
• implications for important habitats
• wildlife species that they support
• the ability of people to experience and enjoy nature

It is vital to maintain and enhance wildlife corridors:

• rivers
• streams
• hedgerows
• wooded areas allow wildlife species to move between different habitat areas, enabling their populations to be more resilient to change

Published in March 2012 requires that planners and developers should aim to conserve and enhance the natural environment through the planning system. These pages offer advice on the measures you can take to ensure that your development meets the requirements of European and domestic legislation that protects our natural environment.

All new development should contribute proportionately to the enhancement of biodiversity and create habitat wherever possible, from small measures such as the installation of nest boxes to the design and integration of large Sustainable Drainage Systems (SUDs) and even landscape-scale schemes of several hectares.

At the design stage of any development, the existing ecology of the site and surrounding area must be taken into consideration. Ecological assessment of the proposed location will identify existing habitats and species present on the site and any potentially damaging effects on them, as a result of the proposed development.

Does my application need to be supported by ecological information?

For all applications use the guidance form (opens new window) to understand if your application needs to be supported by an ecology survey.

Ecological surveys and assessments should be:

• carried out by suitably experienced, trained and qualified ecological consultants holding, where relevant, protected species licences
• carried out at appropriate times of year in suitable weather conditions - surveys conducted outside optimal times may be unreliable
• carried out to published guidelines and methodologies

Writing ecological surveys to inform the planning decision

Consideration should also be given to how the proposed development fits into the existing landscape, including:

• adjacent parks
• open spaces
• designated sites
• gardens

All of these make a valuable contribution to green infrastructure and wildlife corridors in urban areas and the likely effects of development should not be overlooked.

It is important to note that an absence of evidence of a species does not necessarily mean that the species is not there, or that its habitat is not protected. Once an assessment of existing ecology has been carried out, the potential to enhance wildlife value within the new development should be evaluated.

Do you have great crested newts on your site? Would you be eligible for district level licensing (DLL)?

There are now a few different ways to apply for a licence from Natural England to do development or other work that may affect great crested newts and find out how much you may need to pay:

• Swindon and Wiltshire has a GOV.UK Protected sites and species Guidance - Great crested newts: district level licensing scheme (opens new window), a quicker and simpler option compared to obtaining a GCN mitigation licence
• Applying for a GCN mitigation licence (opens new window)
• Or via an ecologist who is a registered consultant under our low-impact class licence scheme

Benefits of DLL

• better conserves great crested newts
• is simple to use
• offers developers certainty in terms of costs and timescales
• means developments that have been through planning will not be held up by protracted post-planning licensing
• results in lots of high value, secure ponds for newts which are managed and monitored for the long term

More information

In autumn 2019, Natural England ran a series of webinars with the Chartered Institute of Ecology and Environmental Management (CIEEM) to provide more information on district level licensing:
YouTube: CIEEM Webinar: District Level Licensing for Great Crested Newts (opens new window) - scheme overview
YouTube: CIEEM Webinar: District Level Licensing for Great Crested Newts - eDNA Survey and Data Collection (opens new window) - evidence base #1
CIEEM Webinar: DLL - Species Distribution Modelling (District Level Licensing) (opens new window) - evidence base #2
YouTube: CIEEM Webinar - DLL: Habitat Delivery for this Natural England-led Scheme District Level Licensing NE-led scheme (opens new window)
YouTube: CIEEM Webinar District Level Licensing - How to apply (opens new window)

Data open to all

As part of the district level licensing project, Natural England completed the largest ever survey of its type for great crested newts across England, funded by the Ministry for Housing, Communities and Local Government (MHCLG). Read their gov.uk blog (opens new window) to find out more.

Other things of interest

Read more about Natural England's Geography in Government Award for their species distribution modelling for the district level licensing project (opens new window).

Avoidance of potential impacts should be a major factor in the design of the proposal and such measures should be outlined within the Design and Access statement.

Consideration should be given as to how this might be achieved, e.g. by moving the site boundary or by altering the construction method.

Mitigation will only be considered where potential impacts cannot be avoided. The relevant industry guidance for species-specific mitigation can be searched for via the CIEEM (opens new window) website.

Where necessary, mitigation should be proposed to reduce the unavoidable impacts of the development on the ecology of the site. Mitigation should be designed in accordance with established best practice, although innovative mitigation designs will be welcome providing they can demonstrate a high level of confidence that they will succeed. For further information read avoidance, mitigation and compensation of impacts to biodiversity.

Instigating best practice on site for all but the smallest developments will require the production of a Construction Method Statement (CMS), which would normally be secured through a planning condition of any permission granted. The CMS will describe how each element of the proposal is to be carried out and what measures are taken at each stage to ensure the protection of biodiversity both within the site and in the surrounding area, and where it is possible that an impact may occur off site as a result of on site processes. For more on construction method statements read writing a construction method statement to support a planning application.

Habitat enhancement (as required by the National Planning Policy Framework) should be specifically designed, to help meet targets set out in Wiltshire's Biodiversity Action Plan (BAP), for the latest Biodiversity Delivery Plan for Wiltshire please visit the Link2Nature (opens new window) web page. It should name the habitats/species it is designed to benefit and give justification as to its appropriateness. The consultant ecologist should input into the design of habitat enhancement which should be submitted as part of the planning application for approval by the local planning authority's planning officer and ecologist.

Core Policy 50 of the Wiltshire Core Strategy requires all development to demonstrate no net loss of biodiversity and for major applications the expectation is that development will deliver a net gain. The National Planning Policy Framework (NPPF) also encourages applications to deliver measurable net gains (para 175 d) and the government has signalled its intention to bring forward legislation to require development to deliver 10% net biodiversity gain. This is covered in its response to the Net Gain consultation (opens new window) and in the Environment Bill 2020 which is currently at the Commons committee stages. Natural England has prepared version 4.0 of the Biodiversity Metric. At the current time therefore, the council expects all applications to demonstrate no net loss of biodiversity and where appropriate to deliver a net gain.

In addition, applicants should make themselves aware of advice and policies in Neighbourhood Plans, for example the Corsham Batscape Strategy. Applications in the Trowbridge Community Area extending towards Westbury must also comply with the  Trowbridge Bat Mitigation Strategy SPD (PDF) [5MB] (opens new window) which has specific habitat requirements in relation to the Bath and Bradford on Avon Bats SAC.

Wiltshire Council will pay our third party contractors directly.

You will only need to coordinate with our third party contractors once the project starts and arrange site visits, dates and access for works etc. All other project management and payment will be cared for.

They are designed so that the liquid and solid waste is separated, with the liquid being released into the surrounding soil (a drainage field) where it can be assimilated ('eaten') by the bacteria naturally occurring in the soil. However, sometimes septic tanks have been placed too close to surface water bodies, or they become affected by groundwater or, increasingly, surface water flooding. In this way, the effluent they release can reach rivers and streams as pollution. Moreover, if a septic tank malfunctions, it may also release untreated effluent.

Package treatment plants (PTPs) not only separate the waste, they also biologically treat them to produce bacteriologically safer and clearer water. This is why they are legally allowed to discharge straight into a water course, whereas septic tanks are not. The PTPs being used in this scheme are also designed to remove some excess nutrients from the wastewater, which cause pollution if released. In addition, if tertiary treatment is used in series with a PTP, this results in the highest water quality standards being reached.

This is a scheme designed to benefit both the environment and the homeowner. As well and having the substantial cost of replacing your system covered entirely, and having the project managed on your behalf, the funding will also cover a 1 year service plan. These benefits are, of course, additional to helping to reduce pollution inputs into our waterways.

Roughly 25 years if it is well maintained.

If your system is well maintained and service according to the manufacturer's guidelines, it should not smell. Foul odours will be a symptom of an issue.

Yes. A sewage plant requires the addition of oxygen into the water which is added through an air blower or air compressor. This can produce a humming sound.

Each system varies in energy consumption, and the type of system opted for will be recommended by specialised engineers. As an example, the energy running costs may be around £0.20-0.80 per day.