PT: Pavement Technologies

Post by JeraleeA Aug 11th, 2010
at 8:33 pm

Hi DonnaD, these are great comments. We will be sure to incorporate them in the next errata sheet and Manual version. We will definitely address the issues you have brought up with respect to wording mix-ups. Thank you for helping us improve this credit!

Regarding the terms "relatively sparse," this is what we mean. We know of many permeable pavement laboratory tests and a handful of test sections usually as non-motorized paths. There are significantly fewer practical applications that have had the benefits of systematic, effectively collected long term performance data in a broad number of locations, especially on highways and other trafficked areas. However, if you know of references for these areas that have not been addressed in the PT-2 Research section, please let us know and we will definitely incorporate this new knowledge.

Post by DonnaD Aug 11th, 2010
at 3:29 pm

Under the Permeable Pavement section there are a few points that are either incorrect or need clarification.
PT-2 page 4 under Block Pavers it notes that "infiltration rates tend to be 13-15% of total rainwater". This is incorrect - permeable interlocking pavements can infiltrate up to 100% of rainwater under most design storm conditions. The 13-15% number often refers to the "open area" or void spaces in the pavement surface. This does not correlate to the amount or rate of infiltration.
PT-2 page 6 under Potential Issues No. 1.
"Continuous maintenance is an issue." Wording here could be revised to say "Regular maintenance is recommended to maintain high infiltration rates."
PT-2 page 7 first paragraph - This paragraph's first line is problematic. One might believe you can simply lay traditional pavers or stone with wider joints and fill in the gaps with aggregate. This may be feasible for pedestrian applications, however under vehicular traffic loading, shifting of the stones would be highly likely. True permeable pavers have either special joint spacers to create wider joints, or void openings that are created when the pavement is installed. This is important to maintain interlock and support vehicular loading. Also, though the rest of the paragraph refers to turf and grid reinforcement as permeable pavement options and goes on to say they don't have the structural capacity to carry loads, it could be interpreted that the pavers in the first sentence also have this problem, which they don't - they are capable of supporting heavier vehicular loads.
In the second paragraph under "How Do Permeable Pavements Work" in the third sentence it says "The void space acts like a sponge and filter..." Actually it is the aggregate base materials and the exsiting soils that filter the pollutants, whereas the void space acts to hold the volume of water coming into the system.
Under "Existing Literature" on this same page it notes that data is relatively sparse for permeable pavements, however, there has been quite a large number of studies for all types of permeable pavements over the last 10 years. This information can be provided if needed.