Effects of Vacuuming Pervious Concrete on Infiltration Rate

The objectives of this research were twofold: test the infiltration rate of pervious concrete before and after vacuum cleaning, and assess infiltration variability over time. Infiltration tests were performed on a 558.2 m2 area of pervious concrete, divided into sixteen 0.35 m2 test areas in a parking area at the Science Museum of Virginia in Richmond, Virginia on five dates from November 4-December 30, 2013. Average infiltration rates (avg.= 22.8 and 36.3 L/m2/min) immediately after vacuuming were lower than those (avg.=30.7 and 41.3 L/m2/min) before vacuuming. We hypothesize that the vacuuming lifted materials towards the surface from deeper crevices of the lower profile of the pervious concrete, which clogged interstices in the upper portion of the pervious concrete, and impeded infiltration. Over time, however, average infiltration rates recovered, increasing significantly from 22.8 -44.1 L/m2/min (93% increase) from November 4 through December 30, 2013 (56 days). Ergo, over time, the infiltration capability of the pervious concrete increased as rains likely washed sediments to lower profiles and allow for increased infiltration rates, consistent with the findings of other studies. Infiltration rates on the leading edge of the pervious concrete area receiving runoff from adjacent impervious asphalt surfaces were significantly lower than those furthest away from the leading edge. In contrast to recommendations specifying that pervious concrete be regularly vacuumed monthly, we propose that annual or semiannual vacuuming of pervious concrete would allow adequate infiltration, and reduce costs significantly for pervious concrete areas located in the mid-Atlantic region.