Real-Time Rainfall and Infiltration Rates in a Pervious Concrete Test Bed

This research examined the infiltration rates on the surface of a pervious concrete (PC) test slab in Beaumont, Texas, and the infiltration rate into the soil below the underground aggregate storage bed. The site has very slow infiltrating clayey soils, and the trials are intended to provide information on the efficacy of using green stormwater infrastructure (GSI) in similar areas. The slab and associated storage bed measured 10 ft by 20 ft, with a total depth of 22 in. An analysis of the void ratio of the aggregate bed provided a relationship between the water depth in the aggregate bed with the soil infiltration rate. Furthermore, the relationship between the water depth in the bed was studied for a combined PC and rain garden (RG) system. The surface PC infiltration rate measurement was carried out using a single ring infiltrometer and for the newly placed slab was on average 1,450 in./h. The soil infiltration rate was measured with a real-time water level sensor with an associated rain gauge. The soil infiltration rate was estimated to be 0.01 in./h. With the combined PC/RG system the rate of the draindown of the water level in the pervious concrete storage bed at times doubled for larger storms, indicating that the rain garden may have aided in its effectiveness, possibly by evaporation or other processes.