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Improving Biosolids Management with Targeted Sludge Surveys

Hydrasurvey completed comprehensive sludge surveys at 22 lagoon and raw water cells across five sites in the Grande Prairie region to support in the development of a proactive lagoon management strategy. This initiative was launched to provide accurate baseline data, identify critical maintenance priorities, and support tendering efforts for desludging and dredging projects.

Overview

For each location, Hydrasurvey delivered a full suite of digital and spatial assets, including:

  • Detailed 3D sludge maps

  • GIS datasets and mobile-ready QField integration

  • xyz bathymetry files of sludge, liner, and topography

  • Dewatering polymer recommendations

  • Geotube testing

  • PFAS analysis

  • Disposal recommendations and regulatory compliance summary

Project Deliverables

Key Findings

  • Sludge accumulation across surveyed cells ranged from 11% to over 56% of total capacity.

  • Some cells exceeded Class 2 landfill acceptance criteria due to elevated contaminant levels (e.g., toluene).

  • Localized sediment accumulation near inlets posed risks for hydraulic inefficiency and plugging.

  • Biosolids in most cells were suitable for agricultural land application or landfill disposal, depending on the cell.

Maintenance Recommendations

Hydrasurvey identified and prioritized several near-term actions:

  • Desludging of anaerobic and shallow facultative cells with high sludge loading

  • Aquatic vegetation harvesting to mitigate organic loading

  • Repair of berm erosion and damaged fencing

  • Sediment dredging in areas of critical accumulation within raw water ponds

  • Development of vegetation control plans to reduce access issues and biological contributions

Disposal Strategy & Suitability

Each cell was evaluated for biosolids reuse or landfill disposal using current Alberta regulatory criteria. In most cases:

  • Land application was the preferred option due to its cost-effectiveness and environmental benefit

  • Landfilling was recommended only when specific contaminant thresholds were exceeded

  • Further third-party consultation was advised for cells with borderline contaminant profiles

Dredging Quality Management Approach

Hydrasurvey outlined quality assurance methods for both tractor-pump desludging and cutterhead suction dredging:

  • Visual inspections and dry tonnage verification by contractors

  • Post-dredge sludge surveys to confirm material removal

  • Use of flow meters, geotube monitoring, and dry-down sampling for production tracking

  • Recommendations for third-party oversight to maintain dredging standards

Innovative Field Tools

Hydrasurvey equipped the client with mobile-enabled sludge mapping via the QField app. This allowed on-site personnel to:

  • Locate high-sludge areas from any device

  • Improve dredging efficiency through spatial planning

  • Strategically apply bioaugmentation

  • Validate contractor performance during removal

Opportunities for Improvement

Hydrasurvey identified several improvement initiatives to reduce long-term sludge accumulation and improve lagoon operability:

  • Vegetation removal to enhance access and reduce biological loading

  • Sub-aquatic weed harvesting in targeted cells

  • Upgrading solids screening at influent points

  • Bioaugmentation as a lower-cost alternative to capital upgrades

  • Establishing 1–5 year sludge monitoring intervals based on site conditions

Project Impact

This lagoon management project empowered the client to:

  • Prioritize and schedule desludging projects

  • Optimize capital and operational spending

  • Meet and prepare for regulatory compliance

  • Increase lagoon lifespan and hydraulic efficiency

With Hydrasurvey’s support, the client is now equipped with actionable data, a practical maintenance roadmap, and tools to engage qualified dredging contractors confidently.