Data Analysis Protocol for Using Resistivity Array as an Early-Warning Wastewater Pond Leak Detector

Abstract

Mineral and organic salts from beef manure in runoff alter the resistivity properties of soil and water. Typically, holding ponds are used to control runoff from concentrated animal feeding operations. The integrity of these holding ponds has come under increased scrutiny since subsurface leakage has the potential to affect soil and groundwater quality. Traditionally, leaks from holding ponds are detected by installing a series of monitoring wells at strategic locations near the pond to intercept any contaminants that reach groundwater. Monitoring wells are expensive to install, costly to sample, generate information that is difficult to interpret and can only warn of a leak after contamination of groundwater has already occurred. A method was developed to continually measure the soil quality around the perimeter of holding ponds. When a change is detected, a message can be sent to facility managers to alert them of potential problems. However, the analysis of the data generated by this new method can be difficult to interpret. A protocol was developed that has 1) a site-calibration method to tailor analysis for most geologic and geographic settings, 2) establishes statistical-based thresholds for detecting changes in soil and groundwater quality, 3) allows for detection sensitivity to be scaled, 4) provides a filter for reducing false-positive leak detections and 5) provides a consistent framework for regulatory reporting. The protocol is designed to be incorporated into automated software that can immediately notify pond managers of potential problems using currently available telecommunication technology.