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Evaluation of Surface Infiltration Testing Procedures in Permeable Pavement Systems
Brown, R. AND Mike Borst. Evaluation of Surface Infiltration Testing Procedures in Permeable Pavement Systems. JOURNAL OF ENVIRONMENTAL ENGINEERING. American Society of Civil Engineers (ASCE), Reston, VA, 140(3):04014001, (2014).
The ASTM method (ASTM C1701) for measuring infiltration rate of in-place pervious concrete provides limited guidance on how to select testing locations. Research was conducted on three different types of permeable pavement materials (pervious concrete, porous asphalt, and permeable interlockng concrete pavers) in order to evaluate how testing sites should be selected and how results should be interpreted to assess surface condition.
The ASTM method (ASTM C1701) for measuring infiltration rate of in-place pervious concrete provides limited guidance on how to select testing locations, so research is needed to evaluate how testing sites should be selected and how results should be interpreted to assess surface condition. The ASTM method is written specifically for pervious concrete, so additional research is needed to determine the applicability of this method to other permeable pavement types. In 2009, the U.S. Environmental Protection Agency constructed a 0.4-ha (1-ac) parking lot in Edison, NJ, surfaced with three permeable pavement types in each of the head-to-head parking rows [permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA)]. An additional single parking row at the northern end of the lot was surfaced with pervious concrete (PC-N). Two methods were used to select infiltration testing locations. Randomly selected locations across each area were tested periodically (about monthly), and other measurements were made quarterly at fixed locations. For periodic monthly testing, six randomly-selected locations were tested on each of the four permeable pavement sections from December 2009 to May 2010, September 2010 to May 2012, and August 2012. Infiltration rates were significantly different across each pavement type. The surface infiltration rates of both PC sections were about twice as large as PICP, and all three were more than one order of magnitude larger than PA. Comparing the two pervious concrete sections, the 0.2-m (8-in.) thick section (PC-N) had a slower infiltration rate than the 0.15-m (6-in.) thick section (PC). The PA results were comparable to some previously published studies and much less than others because of different PA surface course design gradations. With almost three years of use, maintenance has yet to be required, although infiltration has decreased in areas immediately downgradient of contributing drainage areas and to a greater extent where disturbed soil was present. The longevity was attributed to the clogging mechanism. The primary solids source was the upgradient impermeable asphalt driving lanes. Runoff transports solids to the upgradient edge of the permeable pavement surface. The solids concentrate and collect at this location as the runoff infiltrates through the surface. As surface clogging progresses from the upgradient edge, the method of selecting a random location across the entire area typically resulted in most locations being on an unaffected area. Even when one test measured that the surface was clogged near the upgradient edge, the effect was generally diluted by averaging with the larger infiltration rates from unaffected locations. This did not produce a meaningful change in infiltration rate to suggest maintenance was needed for the entire surface area. It is recommended that future surface infiltration testing should strategically select fixed testing locations based on expected clogging patterns.