El documento desde el punto de vista jurídico

The Sustainable Drainage Systems (SuDS) stormwater management approach is an engineering concept, replacing traditional drainage strategies, to mitigate flooding in urban areas. Traditionally, its purpose is to manage stormwater runoff from

impermeable surfaces so that the risks posed to the natural environment are eliminated, minimised or mitigated (Woods-Ballard et al., 2007). The SuDS

stormwater management approach also aims to enhance the natural environment, for the benefits of both human and wildlife, as far as possible (Woods-Ballard et al., 2007).

Aside from flood prevention, the SuDS approach can treat stormwater at source, on site and regionally, to ensure better water quality upon its eventual release, thus reducing diffuse pollution from entering into natural waterbodies (Woods-Ballard et al., 2007; Ellis, 2013). The SuDS approach can prevent, reduce or mitigate flooding and improve water quality using naturally occurring methods such as attenuation, evapotranspiration, infiltration and retention (Woods-Ballard et al., 2007; Ellis, 2013; Uzomah et al., 2014).

The SuDS approach has three main objectives: to manage the quantity of urban run- off, to control the quality of urban run-off, and to enhance amenity and biodiversity of the concerned area (Woods-Ballard et al., 2007; Ellis 2013; Scholz et al., 2013; Department for Environment, Food and Rural Affairs, 2014; Uzomah et al., 2014). Overall, quantity, quality, amenity and biodiversity govern all SuDS designs and implementations.

The key documentations on the SuDS approach are all published by an umbrella organization, the Construction Industry Research and Information Association (CIRIA), and they are widely used in the industry as standard SuDS design practises. The following are some of the key CIRIA SuDS documents:

• R156 – Infiltration drainage: manual of good practice (Bettes, 1996), • C521 – Sustainable urban drainage systems: design manual for Scotland

and Northern Ireland (CIRIA, 2000),

• C582 – Source control using constructed pervious surfaces: hydraulic, structural and water quality performance issues (Pratt et al., 2002), • C609 – Sustainable drainage systems – hydraulic, structural and water

quality advice (Wilson et al., 2004),

• C625 – Model agreements for sustainable water management systems (Shaffer et al., 2004),

• C635 – Designing for exceedance in urban drainage, good practice (Balmforth et al., 2006),

• C697 – The SuDS manual (Woods-Ballard et al., 2007),

• C687 – Planning for SuDS, making it happen (Dickie et al., 2010),

• C712 – The benefits of large species trees in urban landscapes: a costing, design and management guide (Armour et al., 2012),

• C713 – Retrofitting to manage surface water (Digman et al., 2012). The document “C697 – The SuDS manual” (Woods-Ballard et al., 2007) sets out all the key SuDS issues and it is often used as the industry standard source of

information in any SuDS design works. Therefore, details of the SuDS approach in this section are mostly provided by the SuDS manual.

There are other similar concepts of stormwater management in existence. The three most familiar are Best Management Practises, also known as BMP, Low-Impact Development, also known as LID, and Water-Sensitive Urban Design, also known as WSUD. Both Best Management Practises (more recently it is being referred to as stormwater control measures (Uzomah et al., 2014)) and Low-Impact Development are concepts developed in USA, whereas Water-Sensitive Urban Design is used in Australia and Netherlands predominately (Rijke et al., 2008).

In the United States, the main driver for stormwater management is the Clean Water Act. It was created in 1972 and modified in 1987 to take account of stormwater runoff (Carey et al., 2012). This is where the term Best Management Practices was first mentioned (Carey et al., 2012). Initially, BMPs are techniques created to tackle point source industrial wastewater discharges (Carey et al., 2012) but since

stormwater runoff was understood to carry substantial environmental threats, BMPs were incorporated within the National Pollutant Discharge Elimination System

(NPDES) Stormwater Program, which was derived after the amendment to the Clean Water Act in 1987 (Carey et al., 2012).

The Best Management Practises stormwater management techniques cover non- structural and structural practises and processes which aim to minimise, eradicate or prevent pollutants from stormwater runoff reaching the receiving waters (Fletcher et al., 2014) and focuse on water quality and flood improvements. Overall, they are techniques designed to manage stormwater sustainably.

The Low-Impact Development stormwater management approach details planning and design management concepts that aim to sustainably control and manage stormwater using Best Management Practices techniques (Hoyer et al., 2011). The Low-Impact Development concept was derived prior to the SuDS approach, but both are similar because they aim to manage surface stormwater runoff using spatially distributed Best Management Practises techniques, such as stormwater wetlands, permeable pavements and ponds. The aim for both LID and SuDS is to utilise these BMP techniques in order to mimic the natural drainage pattern and return the

hydrology of the site to as close to its natural hydrology as possible (Young et al., 2009; Fletcher et al., 2014; US Environmental Protection Agency, 2014).

The Water-Sensitive Urban Design water management approach is broader than SuDS because it deals with the entire water cycle and integrates the management of it into urban design and planning, whereas the SuDS approach only looks at the management of predominately surface stormwater (Ashley et al., 2013). Water- Sensitive Urban Design has three main objectives: firstly, with regards to potable water – it aims to ensure a sustainable supply; secondly, with regards to wastewater – it aims to work to improve the treatment; and thirdly, with regards to stormwater – it aims to ensure the recycling and reuse of stormwater as much as possible (Rijke et al., 2008; Hoyer et al., 2011; Ashley et al., 2013).

In the UK, the management of wastewater and stormwater are directed by the Water Framework Directive (Xenarios & Bithas, 2007; Joint Nature Conservation

Committee, 2010). Groundwater management is also governed by the Water Framework Directive (Joint Nature Conservation Committee, 2010). The focus of this research is solely on surface stormwater management; therefore, only the surface stormwater management capacity of the Water-Sensitive Urban Design approach was examined.

Australia is prone to severe droughts (Coutts et al., 2012). Consequently, the Water-Sensitive Urban Design approach has a strong emphasis on minimising the use of treated drinking water imported into urban areas by capturing and reusing rainwater as much as possible (Rijke et al., 2008; Healthy Waterways, 2011; Coutts

et al., 2012; Stephenson, 2013). As for the Netherlands, the emphasis in implementing Water-Sensitive Urban Design is to mitigate flooding caused by

increased urbanisation and climate change, and improve the country’s water quality, as demanded by European legislation (Rijke et al., 2008).

European legislation, especially the Water Framework Directive, drive the UK’s approach to stormwater management (Joint Nature Conservation Committee, 2010). Additionally, the SuDS approach was introduced into the existing planning regime in England in early 2015 (Milne, 2014; Johnston, 2015). This was in response to requirements documented in the Schedule three of the Flood and Water

Management Act 2010 (Flood and Water Management Act, 2010). The 2010 Act came about after Sir Michael Pitt’s 2007 flood review (Pitt, 2007).

Overall, SuDS, BMP, LID and WSUD are very similar in many aspects. Technological advances and lessons learned can be applied across all four

approaches but the environmental legislation and climate in the UK are different from USA, Australia and Netherlands. Therefore, the SuDS approach is the preferable stormwater management approach to be employed in this country to enable its waterbodies to achieve the WFD’s “good surface water status” by 2027 (Joint Nature Conservation Committee, 2010).