Brief summary

This pilot project undertook a relatively small series of tests.

A geotextile layer within permeable paving construction may be required for a number of reasons including strength to withstand high loadings, poor ground conditions, or the need to prevent the migration upwards of fine sediments.   There is little information available in the literature from comparative studies where parallel testing of permeable paving systems both with and without a geotextile layer have been undertaken.  Since permeable paving systems are increasingly used to meet both hydrological and water quality requirements, if the geotextile is of no benefit to water quality improvements, developmental cost savings should result.
Three different categories of pollutant were applied to panels of block paving (see photo); a suite of five heavy metals; motor oil, and; street dust.

Testing used an accelerated timescale in which the estimated load of pollutants for each of the periods (1, 2 and 7 years) was applied with one year of rainfall (1200mm) over a period of approximately 100min.  The results after 10 years of simulation showed high metal removal rates for all five metals applied (75-95% removal).   No significant difference between the rigs with a geotextile compared to those without could be detected.

Results from the oil test rigs were similar for the first two periods but the overall removal rate declined over the ten years (equivalent) of application. On average, the rig with a geotextile removed 82% of the oil applied, whereas the rig without a geotextile removed 76% but there was significant variation in the results and insufficient information to conclude whether the geotextile is beneficial.

Start date

Late 2009

Finish date

Mid 2010

Organisations involved

Marshalls PLC.  University of Abertay Dundee

Contact

j.mullaney@abertay.ac.uk; Chris Jefferies, c.jefferies@abertay.ac.uk; Euan Mackinnon, euan.mackinnon@marshalls.co.uk