| PERMPAVE Software: Specifying HydroSTON Pavers |
|
The PERMPAVE software program will take you through a series of frames. You will be required to sequentially select: 1. your analysis objective (3 options) 2. your type of traffic application (6 options) 3. the type of paver you want to use: SELECT POROUS PAVERS A popup will now appear at the bottom of the page for: * * Change default value of surface infiltration rate to 4500 l.s/ha * * Set paver thickness to type of traffic application: 80 (HydroSTON 80) - all applications except Industrial Pavements 60 (HydroSTON 60) - Hard Landscapes and some Residential Pavements 50 (HydroSTON 50) - Hard Landscapes and some Residential Pavements HydroSTON 50 and HydroSTON 60 are suitable for pavements closed to vehicle traffic. Use HydroSTON 80 for applications subject to vehicle traffic. Consult HydroSTON permeable pavement brochure for further details. Continue through the PERMPAVE program frames as directed. The 10 year equilibrium value and paver thickness are the only values that require changing when selecting HydroSTON pavers. Note, however, that HydroSTON 80 pavements require 4 mm joints with 1-3 mm crushed rock joint filling. HydroSTON 50 and 60 pavements can be installed with or without joints. PERMPAVE will generally specify 1-3 mm joint material. Special HydroSTON 1-3 mm Joint Filler is supplied by HydroCon in 20 kg bags and 1 tonne bulk bags. EXPLANATION Water permeability tests of samples of HydroSTON 80 pavers conducted in January 2008 by NATA accredited BEMAC Laboratories of Rydalmere, NSW, gave an average test result of 272 mm/min. Tests were undertaken according to test method AS 4456.16 2003.(Test Report) Permeability of 272 mm/min is equivalent to 45,370 l.s/ha (4.54 l.s/m2). BEMAC describes HydroSTON pavers as "free draining" and "outstandingly porous". Taking 45,370 l.s/ha as the tested permeability of HydroSTON pavers in new condition, and assuming (after Borgwardt - see below) that the 10 year equilibrium permeability will fall to 90% of the permeability rate in new condition, we can be conservatively assume an 10 year equilibrium rate of 4,537 l.s/ha. Borgwardt reports an exponential drop in infiltration rate over time that approaches an asymptotic value as fine material accumulates in joint materials. He typifies the effect in the figure below.  Accumulation of fine material in the top layer of a porous paver and in the joints may eventually reduce the infiltration rate to an equilibrium level between 75-90% below the initial infiltration rate. Dierkes et. al. report on field tests carried out in 2001 on a parking area of a supermarket in Stadtlohn, Germany, with a very high daily rate of vehicle use. The pavement, which consists of porous concrete pavers similar to HydroSTON pavers, was constructed in 1986. Infiltrometer testing gave an infiltration rate, 15 years after installation, of 440 l.s/ha in the central area of the carpark ranging upwards to 2000 l.s/ha towards the perimeter. Dierkes et. al. also report on a newly developed machine cleaning process, which if undertaken regularly can ensure that porous pavements retain life time infiltration capacities. The cleaning procedure was applied to a schoolyard in Germany constructed in 1996 with two layer porous pavers. Tests showed that the infiltration capacity of the pavement after cleaning ranged from 1500 and 5250 l.s/ha, substantially above the required level for permeable pavements in Germany of 270 l.s/ha. ___________________ Dierkes, C., Benze, W., Wells, J. (2002): Sustainable Urban Drainage and Pollutant Source Control by Infiltration. 6th Regional Conference on Urban Stormwater, Stormwater Industry Association, Orange, 22-26 April 2002 [PDF 2.54MB]. Reprinted in Waterfall - Journal of the Stormwater Industry Association, Issue 16, Spring 2002, pp 14-18 Borgwardt, S. (2006) Long Term In-Situ Infiltration Performance of Permeable Concrete Block Pavement, 8th International Conference on Concrete Block Paving, San Francisco, November 2006 [PDF 235KB] |