Wastewater treatment plant effluent lagoon survey
Combining our expertise in both bathymetric and aerial survey using unmanned vehicles, 12P Consulting recently completed a waste water treatment plant (WWTP) lagoon survey for a Victorian Water Authority. The lagoons had previously been dredged of sludge and the water authority wanted to confirm the maximum capacity of the lagoons. Typically these types of settlement lagoons contain aerators, baffles and sensors that are guyed in place using steel rope making it difficult to navigate with a remote controlled survey boat. With the aerators switched off, we were able to capture the maximum area possible using a combination of manual driving and automatic mission planning. The automatic mission planning was achieved using the Surfbee remote controller by driving a safe perimeter that was clear of any hazards and then filling in the perimeter with a 5m grid.
Due to the shallow nature of parts of the lagoon owing to a bedrock shelf, some areas exceeded the minimum draft of the boat (30cm). To mitigate data loss in these areas, the entire lagoon footprint was scanned using LiDAR and RGB photogrammetry sensors. The lagoon waterline extent and level was determined using GSNSS survey techniques (with site calibration to a local PM) which then allowed interpolation between the waterline (zero depth) and the closest point captured by the survey boat.
The resulting point cloud below the waterline was sufficient to create an accurate bed contour map of the lagoon with the addition of the above water ground surface capture with our Matrice 300RTK drone.
Aerial site scan with ground contours calculated
Boat trace showing depth and location
Fully processed lagoon survey with bed contours
