Good design usually depends on getting the right relationship between buildings and the spaces that surround them; landscape design can make or break a development scheme. Good landscaping can actively enhance, complement, soften or even obscure development as necessary.
The landscape of North Norfolk gets its unique identity from the natural setting and historical development. New development should respect, respond and enhance this unique landscape character. New development should share common characteristics with its locality and reinforce local identity as well as providing well designed, accessible landscapes and public open spaces.
Designers often refer to green and blue infrastructure as key elements of landscape which will influence the proposal. Green Infrastructure (GI) is a planned and managed network of multifunctional green spaces which can provide a healthy and rich environment. These can include:
- Gardens, including communal green spaces within housing areas
- Green corridors
- Brownfield and greenfield sites
- Urban parks and gardens
- Registered commons
- Village and town greens
- Children's play space
- Natural and semi-natural habitat for wildlife
- Playing fields
- Pocket parks
- Country parks
- Nature reserves
- Sites of Special Scientific Interest
- Scheduled Monuments.
Blue infrastructure would include features such as:
- Rain gardens
- Filter strips
- Attenuation pounds
- Retention pounds
A space within a development is likely to be made up of structural planting, paths, lawns, hardstanding areas, drainage, trees and boundary treatments. These elements will be expensive to change once in place so it is important to get them right from the start. Landscape design should be an overall driving aspiration, considered as a central part of the design strategy.
Trees and vegetation are vital components for liveable, healthy places and provide many health, environmental and economic benefits particularly when considered at an early stage of the design process. Good landscape design should create a living, changing place, and the maintenance of these features can be even more important than that of the buildings. Landscaping should therefore be robust enough to survive and have a proper management strategy in place.
- Landscape should not be treated as a luxury or an afterthought. The role of plants, tress, surfacing, drainage and other elements should be agreed upfront and later expressed through detailed design work.
- Landscaping should take account of time. It can include long-lasting elements such as main routes and major tress, alongside transient elements such as daffodils. Both contribute to placemaking.
- Planting can be achieve quickly and can have a dramatic impact on place and the process of change.
- Dead plants and cracked paths can have a very negative impact. It is vital to ensure the right mix and species and materials are chosen for a particular area.
Understanding the site topography, including natural draining paths, existing water bodies and potential infiltration areas are important for new developments.
Design principles for water management include:-
- Clustering similar land uses as this can ensure that the level of treatment is consistent and more efficient.
- Maximising permeable areas through the use of green infrastructure and permeable paving to help reduce runoff and re charge the groundwater, subject to ground conditions.
- Allocate sufficient space for SuDS - 5-10% of the site is a reasonable initial estimate.
- Rainwater harvesting may be integrated at the individual building scale. Other common practices include the provision of green roofs and walls which hold back water while also providing amenity and biodiversity benefits. Constraints also need to be considered, such as the underlying geology and soil types.
Attempts to reconnect the water cycle should also be made. Opportunities to reuse water should be considered. While these can be done on an individual building scale basis, they become more economically viable when done at a site wide scale.
Wherever possible sustainable drainage systems and permeable surfaces should be incorporated along new streets, subject to discussions with the Council and suitable ground conditions.
The concept behind SuDS (sustainable urban drainage systems) is to copy the natural environment as far as possible and to smooth the flow of surface water run-off by reducing the peaks and troughs caused by rainfall events. As a general rule, the rate of surface water run-off after development should be the same as if the site had not been developed.
SuDS are a requirement of the NPPF on major developments of 10 dwellings or more, or equivalent mixed use developments. The government therefore expects developers to ensure that sustainable drainage systems for management of run-off are put in place unless demonstrated to be inappropriate.
On minor development national policy also expects new development to give priority to the use of SuDS. The applicant will need to consider the viability of any SuDS proposals as part of their drainage assessment of the site. Drainage systems such as swales and attenuation ponds, alongside more hard landscaped features such as drainage channels can form attractive and playful streetscapes and these SuDS solutions must be considered early in the design process.
Choosing the right SuDS system
A feasibility study should be undertaken early in the planning of the development as the choice of SuDS techniques will depend on a number of factors such as:
- the presence of pollutants in the run-off;
- the size of and drainage strategy for the catchment area;
- the hydrology of the area and infiltration rate of the soil (North Norfolk’s Strategic Flood Risk Assessment provides some information and recommendations regarding the suitability of SuDS in a numbers of areas of the District);
- the location of Groundwater Source Protection Zones or contaminated land.
Adoption and Future Maintenance
The applicant will need to provide life maintenance/management plan of the drainage system for the lifetime of the development (100 years for residential development). This plan will need to be approved by the LPA. In the early stages of design, consideration should be given to the arrangements for adoption and future maintenance of the system. This is likely to influence the design just as much as technical considerations. It is recommended that maintenance should be the responsibility of a publicly accountable body, which will often necessitate the payment of a commuted sum or a legal agreement, possibly backed up by the deposit of a financial bond. The adopting organisation should approve the design before construction commences.
- Green roofs or rainwater harvesting: These can reduce flow rates and improve water quality. Green roofs can reduce the peak flow and the total volume discharged, and improve water quality. In addition, they can improve insulation and increase the lifespan of the roof. Rainwater harvesting involves the collection of the rainwater on site and its use as a substitute for mains water, for example in watering a garden or for flushing toilets.
- Permeable pavements: The need for surface water drains and off-site sewers can be reduced or eliminated where run-off is encouraged to permeate through a porous pavement, such as permeable concrete blocks, crushed stone or porous asphalt.
- Swales and basins: These features provide temporary storage for storm water, reduce peak flows to receiving waters, facilitate the filtration of pollutants (deposited and incorporated into the substrate) and encourage microbial decomposition, as well as allowing water infiltration directly into the ground.
- Infiltration trenches and filter drains: Infiltration trenches comprise stone-filled reservoirs to which storm water run-off is diverted, and from which the water gradually infiltrates into the ground. Their longevity is enhanced by incorporating a filter strip, gully or sump pit to remove excessive solids at the inflow.
- Ponds and wetlands: Although these can be designed as wet or dry ponds, or wetlands, they are most likely to also contribute to visual amenity and biodiversity where they include a permanent water body. Ponds or wetlands can be designed to accommodate considerable variations in water levels during storms, thereby enhancing flood-storage capacity. As well as contributing to biodiversity, with careful design such areas can also provide public open space.