Cost-to-Benefit Testimonial for Bio Dredging

Wastewater Lagoon Sludge Reduction and Cost Savings in Wyoming

Proper maintenance is essential for keeping wastewater treatment lagoons operating efficiently and protecting downstream receiving waters.

According to Mark Court, Registered Wastewater Technician with the Wyoming Association of Rural Water Systems, one of the most important components of lagoon treatment is maintaining an active microbial population capable of breaking down organic material and stabilizing wastewater.

Over several years of inspecting wastewater lagoons throughout Wyoming, Court observed a recurring challenge: excessive sludge accumulation.

The Importance of Microbial Activity in Wastewater Lagoons

Wastewater lagoon performance can be affected by many factors, including temperature, organic loading, dissolved oxygen, hydraulic conditions, and sludge accumulation.

A healthy microbial community is an important part of the biological treatment process.

Microorganisms help:

  • Break down organic material

  • Stabilize wastewater

  • Reduce biodegradable sludge

  • Support biological treatment

  • Improve overall lagoon performance

  • Help facilities maintain discharge compliance

During follow-up inspections at several Wyoming wastewater systems, Court reported improvements in lagoon appearance and reductions in accumulated sludge after microbial products were introduced.

“The small amount of money that has been spent on microbial products has saved systems much more in dredging costs.”

Mark Court
Registered Wastewater Technician

City of Cody Wastewater Lagoon Case Study

The City of Cody, Wyoming, provides an example of the potential financial impact of biological sludge reduction.

Based on Court's historical calculations, the wastewater lagoon system was approaching the need for mechanical dredging in 2004.

At that time, the estimated cost of dredging ranged from approximately:

$946,519 to $1,114,575

After several years of microbial treatment and observed sludge reduction, a 2009 estimate placed the projected dredging cost between:

$513,707 and $642,134

Based on those historical estimates, delaying and reducing the need for dredging represented an estimated savings of approximately:

$432,818 to $472,441

Additional Infrastructure Savings

The potential savings extended beyond the direct cost of lagoon dredging.

Court reported that sludge reduction may also have helped the City of Cody avoid or postpone other major expenses, including:

  • Engineering associated with a dredging project

  • Construction of an additional wastewater lagoon

  • Rehabilitation of filtration infrastructure

  • Cleaning or replacement of underdrain piping affected by accumulated sludge

At the time of the testimonial, the estimated cost of constructing an additional pond was approximately $250,000.

Court also estimated that a major overhaul of the filtration system could have added approximately another $250,000.

Biological Treatment of Sludge in Underdrain Piping

According to Court, microbial treatment also helped break down accumulated organic sludge within the lagoon's underdrain piping system.

Reducing this material biologically helped the facility avoid a potentially extensive filtration-system rehabilitation project.

This provided an additional example of how controlling sludge accumulation can affect more than lagoon capacity alone.

Delaying Mechanical Lagoon Dredging

One of the most significant benefits reported in the Cody wastewater lagoon program was the ability to postpone mechanical dredging.

At the time Court prepared his analysis, dredging had already been delayed by approximately five years, and he believed the treatment program could potentially extend that period further.

Based on the conditions and cost estimates available when the testimonial was written, Court estimated that the City of Cody had realized potential savings in the range of:

$932,812 to $972,441

He also projected that, if dredging could be postponed until approximately 2020, total avoided or deferred costs could potentially reach $1.75 million to $2 million, including anticipated inflation.

These figures represent historical estimates made at the time and should not be interpreted as current dredging prices or guaranteed savings.

Biological Sludge Reduction as a Lagoon Management Strategy

Mechanical dredging can be a major expense for small and rural wastewater utilities.

A biological lagoon-management program may help reduce biodegradable organic solids and extend the period between major dredging projects when site conditions are appropriate.

Potential benefits can include:

  • Reduced sludge accumulation

  • Increased usable lagoon capacity

  • Delayed mechanical dredging

  • Lower sludge removal and disposal costs

  • Reduced infrastructure maintenance

  • Improved biological treatment

  • Support for regulatory compliance

For wastewater utilities facing increasing sludge depths, proactive monitoring and biological treatment can become important components of a long-term lagoon solids-management strategy.

Mark Court
Registered Wastewater Technician
Wyoming Association of Rural Water Systems