The site, a 365m2 driveway to a private residence in Beaconsfield, located atop a hill, slopes by 4% (1:25), causing problems with water run-off collecting fines from the existing bound gravel creating severe silting of the drainage system and surrounding hard/soft landscaped areas.
The brief was to implement a sustainable natural stone solution that would cope with rainfall, be aesthetically pleasing, and be more practical to walk and park on.
During site investigations a series of trial bores revealed a subgrade of sandy clay, suitable for a 'Type B - Partial Infiltration' permeable paving system (BS 7533-13:2009).
Following the removal of the top 120mm layer of existing bound gravel, the 70-90mm bedding layer of SteinTec tuffgrit bedding was installed. The new porphyry driveway was laid on top of this by hand in traditional bogen interlocking arc pattern. SteinTec tuffgrit was then brushed into joints, followed by two passes with a 350kg vibrating plate compactor.
The construction has provided a low cost, durable, fully interlocked permeable unbound pavement able to withstand frequent heavy turning traffic whilst providing SuDS-compliant drainage.
Since construction, despite heavy rainfall, water run-off has been reduced by approximately 80-90% and water now reaching the existing drainage system is clear, having passed through the tuffgrit jointing and bedding layers.