Monitoring of Membrane Structures using Unmanned Aerial Vehicle Assisted Photogrammetry

Abstract

High-value assets demand rapid inspection and structural assessment methodologies to ensure maximum availability and operational capabilities. In the case of large structures (e.g. aircraft wings, dams, vertical tanks, elevated highways), the ability to add non-contact measurement capabilities to unmanned aerial vehicles (UAV) has resulted in new options in structural health monitoring and assessment. Large floating covers over anaerobic lagoons in wastewater treatment plants are a type of significant structure that will benefit from the development of this form of non-contact technique. Large membranes are used as floating covers at the anaerobic lagoons at Melbourne Water’s Western Treatment Plant (WTP), Werribee, Victoria, Australia. A critical function of this high value asset pertains to the harnessing of the biogas gas emitted by these lagoons. Without these covers, the biogas will be released into the environment as a damaging greenhouse gas and the opportunity to generate electricity from the biogas will be lost. Therefore, a proactive inspection and management strategy is required to ensure the integrity of the cover and its continued operation. Demonstration of the UAV assisted photogrammetry surveys conducted over the floating cover at the WTP will be the subject of this paper. The results from monthly surveillance of the covers will be discussed. It will be shown that this is a proactive technique that facilitates quantification of the state of deformation of the floating cover due to the dynamics under the covers. These dynamics are attributed to the inflow of the raw sewage, accumulation of bio-gas, “scum-berg” formation and its movement, the effects of wind or a combination of these factors.