Application of an Automated Early-Warning Leak Detector for Earthen Wastewater Holding Structures Using Non-invasive Geophysical Instrumentation

Abstract

Abstract. Wastewater generated during animal production contains contaminants that can degrade soil and groundwater quality as well as impact human health. Typically, wastewater is stored in earthen-holding ponds until it can be properly disposed. Monitoring wells are the principal tool used for detecting subsurface leakage. There are implicit difficulties when using monitoring wells for detecting wastewater pond leakage. An alternative to monitoring wells based on resistivity array (RA) technology was developed to improve early detection and mitigate soil and groundwater contamination. The objectives of this paper are to explain the development of the technology sensitivity, discuss the advantages compared to monitoring wells and then illustrate the application of the technology based on the advantages. To improve early detection, monitor multiple sides of a pond using one array and eliminate many physical site limitations, correction geometric factors (GF) were developed. These GF were generated using georeferenced probe locations and applied to non-collinear arrays to correct for angular discontinuities. Next, a near-surface data analysis protocol was developed that had user-set thresholds to allow scaling of instrument sensitivity. The protocol used a statistically-based process for calibrating the reference data for a wide range of geological and geographical settings. This protocol allowed the RA technology to be automated to continuously monitor for leakage and when thresholds are exceeded, send an alert message to managers of potential problems. These advantages provide substantial improvements for protecting soil and groundwater quality from wastewater pond leakage.