Sewage Lagoon Sludge Removal (Phase I)
ASI Water (ASI) was contracted to complete the compliance sampling for the semi-annual sewage lagoon discharge, on behalf of an industrial client. Based on indicator parameters in the lab analysis, ASI noted that the lagoons may have reached the sludge retention capacity. ASI proposed an investigation to determine the best path forward to assess the depth of solids in the lagoons and determine any potential impact on the operability of the two lagoons at the manufacturing plant.
The following tasks were completed:
- Bathymetric survey using single-beam standard echo sounder;
- Collection of sludge samples from both lagoons to determine the percent solids; and,
- Sludge removal using a floating dredge and Geotube technology.
ASI’s Geo-physical division assessed the sediment deposition using its Odom Hydrotrac (single-beam survey standard echo sounder) to produce the bottom profile of the lagoons. When compared to the Ministry of Environment and Climate Change (MOECC) Certificate of Approval (CofA), ASI found that the lagoons were operating at approximately 130% of the designed capacity and required to be cleaned out.
Considering the flexible timeline and lay-down space available at the site, ASI proposed an economical method of sludge removal and dewatering utilizing a floating dredge, polymer injection and Geotubes. ASI collected composite sludge samples from both lagoons to determine the best polymer to aid in dewatering. The east lagoon was selected first from the results of the sludge survey. Dredging of the east lagoon was completed in six (6) days, removing a vast majority of the sludge (approximately 450m3), thus increasing the lagoon capacity and restoring the operation in compliance with environmental approvals.
The sludge removal methodology allowed for the lagoon dredging to be phased in order to accommodate the Client’s capital budget process. ASI coordinated and managed all aspects of the project, including sub-contractors, meeting the Client’s schedule and budget while showing performance improvement in the lagoon.
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