CASE STUDY / MUNICIPAL

Municipal Lagoon Sludge Reduction: A Pond 2 Field Project

A municipal lagoon facility in central California dosed one of its lagoon cells with DRP Accelerator, an inorganic compound that carries usable oxygen to the bacteria already in the wastewater, to find out whether biological pre-treatment could reduce sludge without bringing in dredging equipment. We measured sludge depth at a fixed set of points before dosing began and again as the project went on, so the facility could see its own numbers rather than take our word for it.

One pond was already headed for dredging. We measured whether dosing could change that path for the pond next to it.

DRP Accelerator is an inorganic compound that carries usable oxygen to native bacteria already present in a wastewater lagoon, with no bacteria or enzymes added.
When usable oxygen is available, bacteria stop stripping oxygen from sulfate, the reaction that produces hydrogen sulfide (H2S) gas.
Aerobic bacteria digest fats, oils, grease and settled organic solids faster than the anaerobic bacteria that dominate an oxygen-starved lagoon.
A Sludge Judge survey at fixed, GPS-referenced points is a repeatable way to compare a lagoon's sludge depth before and after treatment.
Water depth in a lagoon can shift with irrigation drawdown, so a sludge depth survey logs water depth alongside the sludge reading.
Dosing at a lift station upstream of a lagoon lets treatment reach the wastewater before it ever enters the pond.
A field project built around a baseline survey and two follow-up surveys on the same grid produces a before-and-after comparison rather than a single reading.

Published September 9, 2026

The system

Our field project ran at a municipal treatment facility in central California. The facility treats wastewater through a system of stabilization ponds. By 2025, sludge had built up across more than one of them. Pond 1 was already expected to need mechanical dredging, and the facility flagged Ponds 2 and 3 as possible candidates for the same work. We ran the project on Pond 2, to see whether dosing could hold that pond back from the dredging path Pond 1 was already on. Pond volume, average flow and loading for Pond 2 are not recorded in the case study document we drew this project from. The document does not name the facility or its town either, and Waste Water Innovations (WWI) is still confirming the facility’s written permission to use its name, so we describe it here by location only.

The problem

Dredging takes a pond out of service and is a disruptive, mechanical project. With Pond 1 already headed that way, the facility wanted to know whether biological pre-treatment could reduce sludge inside Pond 2 enough to put off or reduce that same scope, without waiting to find out the hard way. The facility’s specific decision criteria and timeline for a dredging contract are not recorded in the case study document.

What we did

We dosed Pond 2 with DRP Accelerator, an inorganic compound that carries usable oxygen to the bacteria already living in the wastewater. We add no bacteria and no enzymes, and the program runs with no chemical additives. We applied product two ways during the project: a water-based drip at the lift station feeding the pond, and a direct supplement into Pond 2 itself, so the wastewater had oxygen available both before it reached the pond and inside the pond. Exact dose and frequency are not recorded in the case study document. No other additives were used in Pond 2 during the project period. Whether any operational or aeration changes happened elsewhere at the facility during the same window is not recorded either.

How it was measured

We measured sludge depth at eight fixed, GPS-referenced points in Pond 2 with a Sludge Judge, and returned to the same eight points for every round. We took a baseline reading, then repeated the survey partway through the project and again at the end. We also logged water depth at each round, because drawdown from irrigation use moved pond levels over the course of the project, and we wanted the sludge reading tracked separately from that variable. The indicator we followed at each point was the thickness of settled sludge at the pond bottom. The case study document reports the combined total across all eight points at each round rather than the individual reading at each point, so the combined total is the number we publish below.

Results

Total sludge depth across the eight points, added together, moved like this over the project:

Survey round	Date	Total sludge depth	Change from baseline
Baseline	May 27, 2025	105 in	n/a
6 weeks	July 8, 2025	93 in	down 11.5%
12 weeks	August 19, 2025	89 in	down 15.2%

Water levels in the pond shifted during the project because of irrigation drawdown, and we tracked that separately so the sludge reading would not be read as a water-level change. Even with that variation, settled sludge in Pond 2 measured lower at the end of the project than at the start. On the strength of this result, we recommended the facility keep dosing Pond 2 while dredging goes ahead in the other ponds, and keep dosing afterward to help hold sludge down once dredging is finished there too. We also recommended adding a dosing point at the facility’s first lift stations, upstream of the ponds, since the same oxygen delivery that worked on sludge in Pond 2 also works against hydrogen sulfide (H2S) formation and corrosion in a lift station wet well.

Limitations

This is one field project on one pond, with no untreated control pond alongside it, since the facility’s other ponds were on their own dredging track during the same window. We do not have a multi-year record for Pond 2 and cannot say what its sludge depth would have done without treatment. Irrigation drawdown moved water depth during the project, and while we tracked sludge depth as a separate reading at each point, we do not have a documented account of how much drawdown affected the survey beyond what is noted above. Results at another lagoon depend on its own loading, climate and starting sludge depth, and will differ from Pond 2’s. We do not claim that this program keeps a facility within its permit limits. Compliance depends on the whole facility, its sampling and its reporting, and a sludge program is one input to that picture.

Proof assets

The case study document: WWI’s own written case study of this field project, covering the approach, the measurement method and the results above.
The reading table above: total sludge depth across all eight points, by survey round, taken from that same document.
Photos of Pond 2 and the lift station dosing point: on file with the case study document and still to be added to this page.
Permission to name the facility: Waste Water Innovations is confirming the facility’s written permission to use its name, so this page describes it by location only for now.

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