How Sludge Surveys Reduced Dredging Costs by $98,000

Background Effective lagoon management is crucial for wastewater and stormwater facilities, as maintenance costs can quickly escalate without accurate data. Dredging is one of the most significant expenses lagoon owners face. However, many facilities rely on rough estimates or outdated assumptions to guide dredging decisions, leading to inflated costs and inefficiencies. Hydrasurvey has demonstrated that sludge surveys can drastically reduce dredging costs by providing precise sludge distribution and volume data. This case study highlights a sample lagoon project to illustrate the potential savings.

Initial Pricing Without Sludge Survey Data: Three dredge contractors provided pricing for a sample lagoon cell based on general assumptions and industry norms. To ensure comparability, the following variables were excluded from the cost calculations:

• Mobilization
• Dewatering
• Disposal
• Aeration

The pricing was solely for sludge removal and yielded the following results:

• Low price: $96,000
• High price: $243,000
• Average price: $133,000

These estimates were based on incomplete information about the lagoon’s sludge distribution and volume, forcing contractors to factor in significant contingencies to cover potential unknowns.

Pricing With Sludge Survey Data Hydrasurvey conducted a sludge survey of the same lagoon cell, providing contractors with detailed data, including:

• Sludge distribution maps
• Total sludge volume
• Sludge dry tonnes

Using this data, contractors revised their bids for the project, maintaining the same scope assumptions:

• Low price: $25,000
• High price: $40,000
• Average price: $34,000

Key Results By integrating sludge survey data into the dredging planning process:

• The average price dropped by $98,000, representing a 74% reduction in estimated dredging costs.
• Contractors reduced their pricing contingencies, as the sludge survey data removed uncertainty about the project scope.
• Lagoon owners gained confidence in the accuracy of the estimates and the fairness of the pricing.

Conclusion

This case study highlights the substantial cost-saving potential of sludge surveys. By investing in detailed sludge distribution and volume mapping, lagoon owners can:

1. Eliminate unnecessary contingencies in contractor pricing.
2. Optimize budgeting for maintenance projects.
3. Improve the predictability of long-term lagoon management costs.

Hydrasurvey’s innovative sludge survey approach not only delivers operational insights but also transforms financial outcomes for lagoon owners. In this example, the cost of a sludge survey—a fraction of the dredging savings—proved to be an invaluable tool for responsible and efficient lagoon management. By adopting this data-driven approach, lagoon owners can achieve significant savings while ensuring the sustainability of their operations.