Permeable Block Paving Driveway, Exeter, Devon.
Welcome to the daily permeable block paving driveway blog of Kerry Jackson, proprietor of Jackson’s Landscape Design, JLD, the home of quality garden design, landscaping, composite decking, artificial grass, patio design and paving and driveways.
This blog post shows the daily life of our permeable block paving driveway build in Exeter, Devon. It includes plans, before images and daily photos from commencement to completion together with detailed descriptions of the entire process.
What is Permeable Paving?
Permeable paving is a range of sustainable materials and techniques for permeable pavements with a base and subbase that allow the movement of stormwater through the surface. In addition to reducing runoff, this effectively traps suspended solids and filters pollutants from the water
Why have a Permeable block driveway?
As urban and industrial areas throughout the country have continued to expand, the total area of impermeable surfaces such as roofs, roads, pavements and car parks has increased. This means that rainfall cannot infiltrate naturally into the ground quickly enough and put our already overloaded drainage systems to an even greater test. The aging traditional drainage systems are high maintenance and no longer able to cope.
Rainwater which would normally recharge groundwater or wetlands is now washed directly into water courses via conventional drainage systems. With global warming leading to increased levels of rainfall, our ageing drainage systems are no longer able to cope with high volumes of storm water run off. This leads to flash flooding and increased pollution.
During periods of dry weather heavy metals, hydrocarbons, oil, rubber and other pollutants are deposited on impermeable surfaces. When it rains these pollutants are washed into drainage systems and end up further downstream in rivers where they damage wildlife habitats.
The Environment Agency report on the Autumn 2000 floods in the UK, entitled “Lessons Learned-Autumn 2000 Floods” concluded that an estimated 1.85 million homes,185,000 commercial properties and 5 million people in the UK are now at risk from flooding.
The Environment Agency’s publication “Policy and practice for the protection of floodplains” states that: “Inappropriate development within floodplains should be resisted where such development would itself be at risk from flooding or may cause flooding elsewhere.” To minimise any increased surface run off, new developments must be carefully located and designed. Where appropriate, storm water source control measures, which also improve water quality, should be incorporated into the development proposal.
What are the benefits of a permeable driveway?
The solution to flooding problems is the use of more sustainable methods of stormwater drainage which take into account quantity, quality and social issues. These are now referred to as SUDS (Sustainable Urban Drainage Systems). SUDS are made up of a number of structures, which include:
• Permeable pavements
• Swales and filter strips
• Basins and wetlands
• Infiltration devices are more sustainable because they:
• Deal with runoff close to where it falls
• Manage potential flooding at its source
• Protect or enhance water quality
• Provide a habitat for wildlife in urban areas
• Protect water resources from accidental spills and pollution
• Allow new development in areas where existing sewerage systems are at full capacity, enabling new development
within existing areas
• Are sympathetic to the environmental setting and the needs of the local community
• Encourage natural groundwater recharge. The inclusion of a permeable paving surface as part of a SUDS solution will not only increase the likelihood of planning
proposals being approved but may also offer the developer a 10-15% cost savings over traditional methods due to a
significant reduction in drainage costs (pipes, manholes, petrol interceptors etc). Machine laying the paving blocks also
How to install a permeable driveway.
Sub-base: 20mm aggregate at a depth of 200mm
After putting the required 200mm depth of stone in position in layers of 100mm, it needs to be re-orientated using either a tamdem roller or a plate vibrator.
Bedding layer: 3mm laying course material
The bedding layer should be screeded over the 20mm.
When the blocks are placed to the chosen pattern they should be plate vibrated, before the 3mm grit is brushed into the joints until they are completely filled.
All joints must be filled to the top with 3mm grit. Joints,which are not fully filled can lead to possible movement of the blocks after use. JLD recommend that after a few weeks use that any joints, which have settled and are not full, are topped up with grit. Joints should be kept filled at all times. You will need approximately 1 ton of grit for every 100m2 of 80mm paving.
How we installed a permeable block paving driveway in Devon.
Logix concrete shuttering system.
Pins are hammered securely into the sub grade and the appropriate levels are taped to the pins, a string line is wrapped around each pin at the top of tape.
The telescopic fork lift is used to load out the edging kerbs.
A 7m3 concrete lorry carrying RC35 semi dry concrete is backed onto the driveway.
The semi dry concrete is off loaded to the correct height while the driver watches the hand signals given.
Once the concrete has been fully off loaded the edging blocks are installed flush with the line and levelled, the rear of the block is haunched with concrete and a plastic float finishes the concrete.
A small boat level is used to correct each and every block paving edging kerb.
The 45 degree batter of the haunching to the front and rear of the kerbing is consistent and tidy, this eliminates any concrete waste as acts as a strong edging base.