Analysis of Instrumentation Selection and Placement to Monitor the Hydrologic Performance of Permeable Pavement Systems and Bioinfiltration Areas at the Edison Environmental Center in New Jersey

Abstract

Infiltration is one of the primary functional mechanisms of green infrastructure stormwater controls, so this study explored selection and placement of embedded soil moisture, water level, and temperature sensors to monitor surface infiltration and infiltration into the underlying soil for permeable pavement systems and bioinfiltration areas at the Edison Environmental Center in Edison, NJ. In 2009, the U.S. Environmental Protection Agency constructed a 0.4-ha (1-acre) parking lot surfaced with three permeable pavement types (interlocking concrete pavers, porous concrete, and porous asphalt) and six bioinfiltration areas. The six bioinfiltration areas were designed with three different ratios of drainage area to bioinfiltration surface area (5.5:1, 11:1, and 22:1). A series of time domain reflectometers (TDRs), piezometers, and thermistors were installed at various depths in the profile in each control and in the underlying soil. A drain gauge (passive capillary lysimeter) was installed in one bioinfiltration area. The ongoing objective for this research is to develop instrument lists, placement strategies, and data analysis techniques to determine when a deviation in the control’s typical performance occurs to then establish when maintenance or replacement is required. Initial results with TDRs installed in the gravel storage layer of permeable pavement systems have shown that these sensors can measure a different response when water enters the surface as direct rainfall versus rainfall combined with runoff from a contributing drainage area. This change in response represents a condition where the permeable surface upgradient of the TDRs has become clogged, so it also receives surface runoff from the contributing area.