Type of Development Proposed

The category selected should most accurately reflect the proposed development on site.

The property can be considered as either Residential (properties used as dwellings such as housing) and Non-residential (properties used for industrial, commercial, agricultural, infrastructure, schools, community centres such as village halls, doctors, churches and leisure centres). Using these definitions of Residential and Non-residential property, there are nine categories based upon the type of development planned on site, which are;

• Extension to existing residential property less than 250m² (for residential use only)
• Extension to existing property greater than 250m² (for either residential or non-residential use)
• New single property (for either residential or non-residential use)
• New multiple properties with new access road(s) (for either residential or non-residential use)
• New impermeable ground areas (for paved areas of land such as car parks, hard standing and all other types of use not involving buildings)
• Extension to existing basements (for either residential or non-residential use)
• Extension with basements extensions (for either residential or non-residential use)
• Change of property use (for either residential or non-residential use when the building and impermeable area remains unchanged)
• Non-Residential Buildings (Public / Private Sector buildings for non-residential use such as schools, community centres, workshops, industrial commercial, agricultural and infrastructure uses)

If nothing else is proposed 'New impermeable ground areas' should be selected.

Type of Development Surface

The type of development surface affects the water quality requirements of the proposed SuDS solution. The category selected should most accurately reflect the proposed development. There are three categories for residential and five categories for non-residential developments based upon increasing risk of pollution of the surface water runoff.

Residential Developments

• Roofs and paved areas with no vehicle access or sources of pollutants (Lowest risk)
• Roofs, residential roads and parking areas (Moderate risk, pollutants associated with vehicles on smaller roads)
• Residential roads and parking areas (Moderate risk , pollutants associated with vehicles on smaller roads)

Non-Residential Developments

• Roofs and paved areas with no vehicle access or sources of pollutants (Lowest risk)
• Roofs, roads, parking areas or commercial zones (Moderate risk, pollutants associated with vehicles on smaller roads)
• Roads, parking areas or commercial zones (Moderate risk , pollutants associated with vehicles on smaller roads)
• Roofs, industrial areas, loading bays, refuse areas or highways (High risk , pollutants associated with larger vehicles trucks from industrial sites)
• Industrial areas, loading bays, refuse areas or highways (High risk , pollutants associated with larger vehicles from industrial sites)

Impermeable area of existing site

The following surfaces should always be considered to be impermeable:

• Roofs, excluding green roofs and brown roofs
• Hard surfaces at ground level

For permeable hard surfaces at ground level evidence will be required to show they are permeable (e.g. porous asphalt)

Impermeable area after development

Total impermeable area of the whole site once development has been implemented.

The following surfaces should always be considered to be impermeable:

• Roofs, excluding green roofs and brown roofs
• Hard surfaces at ground level

For permeable hard surfaces at ground level evidence will be required to show they are permeable (e.g. permeable block paving or porous asphalt)

Postcode

Postcode is mandatory. It can be entered either by selecting the 'Get Postcode' button once a grid reference is entered. Alternatively the postcode can be entered manually.

Impermeable area after development

Total impermeable area of the whole site once development has been implemented.

The following surfaces should always be considered to be impermeable:

• Roofs, excluding green roofs and brown roofs
• Hard surfaces at ground level

For permeable hard surfaces at ground level evidence will be required to show they are permeable (e.g. permeable block paving or porous asphalt)

Impermeable area after development

Total impermeable area of the whole site once development has been implemented.

The following surfaces should always be considered to be impermeable:

• Roofs, excluding green roofs and brown roofs
• Hard surfaces at ground level

For permeable hard surfaces at ground level evidence will be required to show they are permeable (e.g. permeable block paving or porous asphalt)

Brownfield runoff rate

The Brownfield runoff rate represents the total runoff from the site assuming the site is 100% impermeable.

Percentage betterment

An optional percentage improvement to the post-development runoff rate from the site.

Achieved by providing an additional volume of storage at the site, which reduces the rate of runoff to less than the pre-development conditions

Grid Reference

The grid reference should be entered in Ordnance Survey National Grid format as eastings and northings.

e.g. for County Hall in Lewes the grid reference is

Include leading zeros if applicable

EA Surface Water Map

The Environment Agency flood map allows consideration of the interaction of surface water flooding and flow paths in relation to the site.

The SuDS Tool does not consider flood risk to the site. Additional assessments should be carried out to assess the risk of flooding to the proposed development site and if appropriate, a site specific flood risk assessment should be provided.