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Sludge quantification and distribution at the Darwell Wastewater Lagoon in Lac Ste. Anne County, Alberta​

Client’s challenge: Unknown sludge build-up in cell 1 at the Darwell Wastewater Lagoon and unsure whether dredging may be necessary.
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Hydrasurvey’s solution: Conduct a lagoon sludge survey of cell 1 to determine sludge quantity and composition.
  • The hydrographic survey showed substantial sludge build-up in the northwest corner near the septage dump. Data from the survey also revealed notable sludge accumulation in the southeast corner of the cell at the crossover sump.
  • The sludge distribution data allows dredge contractors to focus resources in areas that are worse than others to ensure the cell is cleaned entirely.
  • Synthetics (rags, plastics, foreign matter) were found to be floating on the cell and washed up on shore in some locations. These objects can pose a risk to pumping and dredging equipment.
  • Excessive sludge build-up resulted in considerable vegetation growth in the sludge beach formed at the septage dump. Removal of aquatic vegetation increases treatment capacity and also reduces the likelihood of animals burrowing into the liner. 

Sludge quantification and influence of aeration on sludge blanket at Town of Fernie, BC Wastewater Lagoon ​

Client's challenge: Identify whether dredging in cells 1 and 2 was necessary and determine sludge volume and composition for dredge project budgeting.
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Hydrasurvey's solution: Hydrasurvey conducted sludge surveys in two aerated cells at the town of Fernie, BC's wastewater lagoon. 
  • The hydrographic sludge surveys determined the in-situ sludge volume, dry tonnes of sludge, sludge composition and showed the influence of the aeration system on the sludge, which allowed contractors to provide accurate pricing to dredge the cells. 
  • The hydrographic sludge survey also showed a possible restriction issue with the aeration in cell 2. A localized build-up of sludge in cell 2 appeared to be burying aeration diffusers and causing more of a sludge build-up near the cell inlet. This allowed the town to specifically assess the aeration in that particular area of the pond.