What can we do to help Oxfordshire’s flooding issue?

Oxford’s Flood Alleviation scheme has provided a glimmer of hope for local business and property owners following severe flooding in 2003, 2007, 2012, 2013 and 2014. Oxfordshire Growth Board have recently announced the scheme has been put on an amber status, now there is a substantial financial gap in funds of £10m. Although the people of Oxford have been reassured the project will continue, allowing the construction of the four-mile flood channel, Rodney Rose, Oxfordshire County Council’s deputy leader, has invited local businesses to contribute financially to the scheme. With some expressing doubt on the willingness of local people to do so. 

The plight of Oxford and its flooding issues, as well as the problems experienced by the rest of the UK, highlights the need to incorporate Sustainable Drainage Systems (SuDS) in any development, and that strategy is at the heart of all we do.

The necessity for Sustainable Drainage Solutions (SuDS)

Oxfordshire has seen its fair share of flooding in recent years, affecting roads, railway lines, schools, businesses and homes, and with substantial urban development and bodies of water in abundance, the issue is unlikely to ease any time soon. The aspects that need to be addressed when designing new developments are the quantity of water (flooding), quality of water (pollution), biodiversity (wildlife and plants) and amenities.

Sustainable Drainage Solutions, (SuDS), should mimic nature, managing rainfall where it falls, but also need to consider the affects they may have downstream on nearing communities; the idea is not to simply transfer the flood risk elsewhere. Creating zero, or minimal, long-term detrimental damage, SUDs are considered the environmentally friendly option.

It’s quite often felt that the look of such SuDS is crucial to its initial appreciation within the community, so not only do the designers need to consider the most effective way to incorporate SuDS, they also need to be aware of its appearance, taking into account the style of the area, ensuring it fits visually.

In order to optimise the benefits of SuDS, the planning and design needs to be incorporated at the start of the development process. Fitting in sustainable drainage mid-way through a project is likely to result in the SuDS being less effective than what it could have been if it was considered holistically, creating problems down the line when the heavy rainfall begins. Additionally, continual efforts to perform a sequence of management practices, control structures and strategies ensures the recurrent benefits of efficient and sustainably drained surface water, all while minimising pollution of any local water bodies.

What do we do to help?

Our designers believe in the importance of a holistic solution for the disposal of surface and foul water, working with the client to develop sustainable drainage techniques from the beginning. To us, sustainable drainage is not an afterthought, and there is no “one size fits all”, therefore each site needs to be assessed individually. 

Implementations from Gemma Design

Here at Gemma Design, we use the very latest hydraulic design software and computer systems, combined with detailed knowledge of current design standards, to deliver integrated solutions for challenging and complex sites.

Where off-site disposal is necessary, we demonstrate a proven track record of securing consent from statutory authorities, through both Section 104 and 106 applications, and land drainage consent, for discharging to watercourses, therefore actively adhering to all local guidelines.

Disposal of foul drainage can be challenging where no existing connections are present, or the infrastructure is at a shallow depth, and in these situations, treatment is needed. Our engineers liaise with the Environment Agency to obtain approval for any on-site treatment, and with sewage undertakers for the installation of pumping stations where necessary.

As flooding becomes an increasing problem, we will continue to carry out any necessary assessments, systems and procedures to continue to develop in the most environmentally sustainable way possible.

What are sustainable urban drainage systems (SUDS) and why do we need them?

Sustainable urban drainage systems (SUDs), is a philosophy that takes into account the long term environmental factors in excess water drainage and are becoming an increasingly important part of planning proposals, with the Government stating:

“The requirement to meet housing needs must be balanced against other important considerations, such as protecting the Green Belt or addressing climate change and flooding”

Plain English Guide to the Planning System

There three main benefits of sustainable urban drainage systems (SUDs)

Although the benefits to SUDs are far reaching, the three main benefits are as follows:

1.      Flood prevention

To sustainably prevent flooding of urban areas populated by homes, carparks and other infrastructure. With an increase in localised flooding in the UK over the last decade, legislation and design guidance is moving towards increased regulations in relation to surface water drainage. Sustainable urban drainage systems are a natural approach to resolving drainage issues associated with property developments and construction sites and working to prevent future surface water flooding in populated areas following the completion of building projects.

2.      Benefiting the environment

A natural process of pollutant breakdown allows the excess water to be re-directed back into the urban watercourses without risk of damage to the habitat or its occupants.

Filter drains and bio retention basins are just two examples of how SUDs can be implemented without harsh impacts on the local aesthetics. They consist of gravel and sand to filter out pollutants before the water enters the wider environment. Permeable paving and filter strips are other examples of how little impact SUDs has on the area in which it is utilised.

As well as keeping flood risks down and providing safer habitats for wildlife, the use of SUDs allows new development of houses and business where existing sewer systems are close to full capacity.

3.      Foul drainage

The purpose of using SUDs to support existing sewerage systems is to naturally treat water close to the source and allow drainage straight into water courses, rather than over burden the sewer systems. This prevents overflowing of sewers in the event of unusually heavy rain fall.

Gemma Design’s engineers frequently liaise with the Sewerage Undertakers over the adoption of new drainage systems and proposed connections to existing systems. We also have strong links with the Environment Agency for obtaining permits where septic tanks and package foul treatment plants are required.

How Gemma Design implements SUDs

With the philosophy behind sustainable urban drainage systems central to Gemma Designs’ own philosophy as civil engineers, we use Micro Drainage software, the industry specific software that produces cost effective solutions for all surface water and foul water systems. Micro Drainage allows us to design hydraulic systems that ensure all our projects stay compliant with relevant legislation.

Gemma Design is proficient in designing systems that include an assortment of interventions such as:

·         Soakaways

·         Pipes

·         Connections with existing systems

·         Flow control

·         Adaptation liaison

·         Headwalls

·         Culverts

Gemma Design keeps informed about the changes of regulations and legislation by staying up to date with the Flood Water Management act 2010, The Sewers for Adoption (7^th Edition), Code for Sustainable Homes and BREEAM (Building Research Establishment Environmental Assessment Methodology).

For further information on the uses and benefits of SUDs please see our website, or get in touch with one of our engineers.

Gemma Design

Department for Communities and Local Government - Plain English guide to the Planning System

NetRegs - Environmental guidance for business