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Methods to Use Surface Infiltration Tests in Permeable Pavement Systems to Determine Maintenance Frequency
Citation:
Brown, R. AND M. Borst. Methods to Use Surface Infiltration Tests in Permeable Pavement Systems to Determine Maintenance Frequency. Presented at World Environmental & Water Resources Congress (EWRI 2013), Cincinnati, OH, May 19 - 23, 2013.
Impact/Purpose:
This abstract will highlight the results from manual surface infiltration measurements conducted at the Edison Environmental Center's permeable parking lot.
Description:
Currently, there is limited guidance on selecting test sites to measure surface infiltration rates in permeable pavement systems to determine maintenance frequency. The ASTM method (ASTM C1701) for measuring infiltration rate of in-place pervious concrete suggest to either (1) perform tests at multiple locations as requested by the purchaser of the testing services or (2) perform three tests for areas up to 2,500 m2 (25,000 ft2) and add one additional test for each 1,000 m2 (10,000 ft2) or fraction thereof. In 2009, the U.S. EPA constructed a 0.4-ha (1-ac) parking lot in Edison, NJ, that was surfaced with three different permeable pavement types [interlocking concrete pavers (ICP), porous concrete (PC), and porous asphalt (PA)]. The surface area of ICP and PA are 494 m2 (5,320 ft2) each, and the total surface area for two sections of PC is 741 m2 (7,980 ft2). The monitoring used two methods to select infiltration testing locations. The first method, randomly selected measurement locations across the area were made monthly. The second made repeated quarterly measurements at fixed sites. For monthly testing, six randomly selected locations were tested on each surface from December 2009 to May 2010 and September 2010 to April 2012. The fixed sites used the selected location during either the second or third month of testing. Infiltration rates were significantly different across each surface. The average infiltration rates for ICP, PC, and PA were 2,080, 4,140, and 150 cm/hr (820, 1,630, and 60 in/hr), respectively. Overall, there has been no statistically significant change in infiltration rate with time for any surface, so maintenance has not been performed to date. A reason for the longevity has been attributed to the clogging dynamics. The primary source of solids was from the upgradient impermeable asphalt driving lanes. Solids associated with runoff wash onto the upgradient edge of the permeable pavement surface and concentrate and collect at this location as the runoff passes through the surface. As clogging progressed from the upgradient edge, the method of selecting a random location across the entire area typically resulted in not measuring a meaningful change in infiltration rate. Even if a test measured the site was clogged, it likely would not have been indicative that maintenance was needed to prevent bypass. To use surface infiltration tests to determine when maintenance is required, it is recommended to strategically select fixed testing locations based on expected direction of clogging.
