CONCRETE & STONEWORK
Sustainable Drainage Urban flooding from rainwater runoff and surcharging sewers is a growing problem with climate change . In response , concrete block permeable paving is becoming far more widespread as a uniquely flexible sustainable drainage systems ( SuDS ) technique . It provides an inherent drainage system with no additional land take for water storage , treatment or conveyance , and eliminates pipework , gulleys and manholes – therefore costing less than conventional drainage and paving .
Essentially , this technology shares the same impressive performance as conventional modular concrete paving products , being slip resistant , durable , strong and sustainable . The difference with permeable paving is enlarged joints , filled with a permeable aggregate , and the materials used below the blocks , which are specifically selected to accommodate water without clogging . Concrete block permeable paving is unlike – and not to be confused with – permeable materials , which behave very differently .
Gradual Supply of Clean Water But there is more to permeable paving than just flood protection . Over decades of successful use , the technology has demonstrated a wide range of other benefits and multifunctionality . Concrete block permeable paving offers a real opportunity to trap vehicle pollution from water runoff and offers designers the exciting potential of a gradual supply of treated water that can be integrated with landscape design to promote biodiversity .
It also provides clean water at the head of the ‘ SuDS management train ’ enabling safe , open SuDS features on the surface , downstream . Concrete block permeable paving can be laid level – and still avoid puddles and potholes – or adapt to slopes . It provides a safe , firm surface for everyone , including wheelchair users and people pushing prams , unlike gravel and other loose materials . It is also the preferred option around trees , rather than tree grilles , according to BS8300-1 ( 2018 ).
Sustainable Regeneration One important innovation , particularly for regeneration , is the retrofitting of permeable paving as an overlay , making new use of existing , conventional road bases or other hard surfaces below and their embedded carbon . These lowintervention , thin overlays create attractive , safe and sustainable shared-surfaces . They can be particularly effective when used to supply a gradual flow of clean water horizontally into raingardens , bioretention areas or tree pits , nurturing trees and other green infrastructure .
Green infrastructure will be a major influence on the public realm in future , with ever more investment in urban tree planting announced by national and local government , supported by policies at all levels . For example , the July 2021 ‘ National Planning Policy Framework ’ states that : ‘ Planning policies and decisions should ensure that new streets are tree-lined and that opportunities are taken to incorporate trees elsewhere in developments ’.
Permeable Paving and Trees in Harmony However , measures need to be put in place to nurture and allow trees to mature , generally for decades , enabling them to actually deliver their real potential – including net carbon storage , urban cooling through shading and evapotranspiration , biodiversity and public wellbeing . So , the NPPF also requires that : ‘ appropriate measures are in place to secure the long-term maintenance of newly-planted trees , and that existing trees are retained wherever possible ’.
Local planning authorities will now need to incorporate long-term tree maintenance measures in their planning consents . Here , permeable paving , providing irrigation and essential air supply ( with CO2 release ) to growing tree roots , so avoiding surface damage by roots , offers a straightforward spatial solution . Although urban trees and paving have traditionally been seen as in conflict , this is not the case with concrete block permeable paving which works in harmony with green infrastructure .
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