The July 2021 National Planning Policy Framework requires that: ‘planning policies and decisions should ensure that new streets are tree-lined…and appropriate measures are in place to secure the long-term maintenance of newly-planted trees.’ Concrete block permeable paving offers a simple solution to these requirements, working in harmony with urban trees.
Urban trees and paving have traditionally been seen as in conflict. But this is not the case with concrete block permeable paving (CBPP), a key multifunctional sustainable drainage (SuDS) technique to reduce flood risk and make cities more liveable. CBPP offers unique opportunities to collect, attenuate and treat rainwater runoff, removing pollutants ready for irrigating trees and other planting. Recent research has demonstrated concrete block permeable paving operating efficiently with minimal maintenance over 20-years amongst extensive tree planting, without root disruption or other issues.
Local planning authorities now need to incorporate long-term sustenance and maintenance measures for trees in planning consents. Concrete block permeable paving provides a straightforward spatial solution – rather than complex legal obligations on developers – with a gradual supply of clean water to irrigate green infrastructure, integrated with SuDS, hard surfaces and urban design.
Retrofitting CBPP as a low-intervention overlay to existing road bases or other hard surfaces is an important innovation for regeneration. The permeable paving collects water across a wide area for supply horizontally into raingardens or bioretention areas with trees and other green infrastructure. Here it is stored for irrigation and biodiversity, while also delivering SuDS.
This approach is exemplified in the regeneration of Bridget Joyce Square, London. Recent inspection, around 5 years after completion, revealed that trees and other green infrastructure were healthy, substantial and particularly well-established, with the permeable paving working effectively.
Interpave would be pleased to hear from anyone considering integration of permeable paving and trees on developments to meet the new requirements (email: chris.hodson@paving.org.uk). For project case studies and guidance on all aspects of permeable paving and SuDS visit: www.paving.org.uk
