Citation:

Brown, R., M. Borst, J. Rivard, H. Kazemi, J. Gray, AND L. Kurtz. Techniques to Determine Maintenace Frequency of Permeable Pavement Systems with Time Domain Reflectometers (TDRs. Presented at World Environmental & Water Resources Congress (EWRI 2013), Cincinnati, OH, May 19 - 23, 2013.

Impact/Purpose:

This abstract will highlight the results of installing time domain reflectometers (TDRs) beneath permeable pavement strips to predict when maintenance is needed at a field application in Louisville, KY.

Description:

As the surface clogs in permeable pavement systems, they lose effectiveness and require maintenance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being conducted using multiple time domain reflectometers (TDRs) beneath the surface to remotely monitor surface infiltration. These instruments are used to measure the relative amount of infiltrating water. As clogging progresses to a TDR location, more runoff infiltrates over the TDR producing a significantly larger response compared to the responses from direct rainfall only. Placement is critical to adequately evaluate surface clogging and develop guidance for maintenance. This research is refining earlier work at EPA’s Edison Environmental Center to establish placement strategies and evaluate clogging dynamics at a field application in Louisville, Kentucky. The Louisville and Jefferson County MSD is installing permeable pavement systems in parking lanes as 2.4 m (8-ft) wide strips that range in length from 16.8 to 36.6 m (55 to 120 ft). TDRs were installed at two strips in December 2011, and will be installed at additional controls in October 2012. Contributing drainage area size and composition influence sediment load making the ratio of drainage area to working width of permeable surface an important design parameter to predict the rate of surface clogging. TDR responses from rainfall events at the first two installed controls support the hypothesis that surface clogging progressed from the upgradient edge. Manual surface infiltration measurements were conducted at each site at least quarterly and immediately before and after maintenance activities. These measurements supported (1) changes in TDR response with the progression of surface clogging and (2) evaluation of whether maintenance restored infiltration capacity. This presentation will describe how TDRs were used to provide guidance for maintenance scheduling.

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