sketch of a two-pond lagoon system for animal waste - UTAH SMALL ANIMAL WASTE LAGOONS AND PONDSSeptic lagoon system maintenance requirements

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Lagoon septic system maintenance requirements

This article describes the maintenance needed for septic wastewater lagoon systems, such as the use of additives (don't), lagoon septic system tank cleaning, how to maximize the life of a lagoon septic system, maintaining the required septic lagoon water levels, periodic removal of sludge from the septic lagoon, mowing & vegetation around a septic lagoon, and how to correct an odor complaint traced to a lagoon septic system.

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Lagoon Wastewater Treatment System Inspection & Maintenance

Article Contents

Reader Question: how do I evaluate the septic lagoon ponds & how to I maintain them

I had a question for you regarding inspection of lagoon/oxidation ponds. If I have a four septic tanks that are connected in series and that have a disposal system to four lagoon/oxidation ponds. How should I go about evaluating the ponds.

What procedure should I take. If you may provide me assistance with this I would greatly appreciate it. Thanks, G.A. 3/26/2014


LAGOON SEPTIC SYSTEMS provides basic design specifications for septc wastewater treatment lagoon systems by combining recommendations from several authorities.

Below is lagoon septic system maintenance advice adapted from from the septic lagoon design and maintenance sources listed in our References & Lagoon Septic System document citations below.

After finding that on single wastewater lagoon design and maintenance guide incorporated all of the helpful suggestions provided by multiple experts, we have combined recommendations from several sources in the information given below.

Watch out: aside from the importance of proper sewage lagoon maintenance to keep the sewage treatment system working properly, there are two essential health and safety concerns:

Lagoon security fencing must be maintained and kept intact to prevent entry by children or other animals.

The lagoon structure and banks must be maintained against erosion to prevent sewage escape to the environment where it may overflow into waterways or contaminate local drinking water.

Sewage Lagoon overflow hazards and lagoon fencing requirements are described in more detail at


Septic System Additves & Treatments for septic lagoon systems

No starter bacteria or other additives are necessary to put a new lagoon into use. However, it is desirable to have the excavated area fully saturated and the lagoon prefilled with enough water for the solids to stay in suspension.

Do not add enzymes, yeast, nor other treatments to the septic tank or to the lagoon itself to "improve bacterial action" - it won't help, it may damage the system, and such treatments are illegal in many jurisdictions.


Planting around a Lagoon Septic System

Grass, preferably short grasses such as bluegrass, should be planted from the design high waste wastewater level up over the dike top and on the lagoon dike slopes to prevent erosion of the dike. Overhanging vegetation at the lagoon edges should be cut back to 6" or less.

Alfalfa and long rooted grasses that might damage the ingegrity of the septic lagoon are not allowed on the lagoon side slopes. Similarly, weeds, cattails, reeds, and other wetland plants are not allowed to grow on the lagoon sides and when they occur they must be physically removed or chemically treated.

Trees, brush, shrubs etc. are not permitted on the lagoon dike nor within setback distances from the lagoon specified by some building codes such as MO Title 124 Ch. 5.

Mowing: Vegetation on the lagoon banks should be mowed often during the growing season to prevent shading and to ensure that breezes can blow across the lagoon water surface to stir in oxygen for proper bacterial action.

Algae vs. duckweed growth in a septic lagoon:

A green covering of algae on the lagoon is normal. However, if duckweed grows and shades more than half of the water surface area, it should be removed.

The ground around the lagoon area must be mowed to keep grass and other plants 6" or less in height on the slopes and on the type of the ike.

See lagoon fencing requirements discussed separately at LAGOON SEPTIC SYSTEMS

Septic tanks for Lagoon Septic Systems

The septic tank should be inspected annually to ensure that it is working properly and to determine when scum and sludge in the septic tank should be cleaned out. Consult MU publication WQ 401, Septic Tank/Absorption Field Systems, for information on septic tank maintenance and cleaning procedures.

Surface water & runoff control around septic lagoon systems

To prevent overflow or "floating out" of the lagoon system during seasonal wet periods of high water table, it may be necessary to install an intercept or curtain drain to keep surface water and groundwater out of the lagoon system itself.

Schultheis gives curtain or intercept drain specifications in the document we cite.

Typically an intercept drain is 1-2 feet in width, at least 6" deep, deeper if you are intercepting groundwater, and the drain is located up-slope from the lagoon at least ten feet away.

A curtain drain trench should itself slope at least 4" in 100 ft. of horizontal run and should dispose of runoff to daylight or to a suitable destination downhill from the lagoon where water will not run back towards the protected area.

Schultheis calls for the perforated pipe holes to be placed "up" which in my [DF] opinion increase the risk of soil clogging; I'd place the peforated holes down as we do for a drainfield pipe and rely on gravel cover and geotextiles to allow water to flow in the curtain drain trench and into the piping.

Schultheis also points out that on a level site it will be necessary to use a pump to dispose of runoff-controlled water.


Lagoon Septic Life Maximizing Steps

Constructed Wetlands, San Miguel de Allende, Guanajuato Mexico, from el Charco del Ingenio botanical garden, by the author, August 2006

[Click to enlarge any image]

Above,constructed wetlands at el Charco del Ingenio, San Miguel de Allende, Guanajuato, Mexico.

In addition to the design and "don'ts" described

at LAGOON SEPTIC SYSTEMS, Schultheis and other lagoon septic experts recommend water conservation

and would subscribe to all of the "Don't Flush" advice we provide


Lagoon septic system failure or performance adequacy problems

Some sources note that for a lagoon that appears to be over-taxed, under-sized, or failing, it may be possible to rescue the lagoon by adding an additional septic tank in series with the existing tank and between the primary tank outlet and the lagoon basin.

Adding a second septic tank can increase the level of wastewater treatment.

A lagoon that was originally built too small or too deep can sometimes be “rescued” by installing a septic tank in the line between the house and the lagoon.

This will reduce the nutrient load that the lagoon bacteria must digest. In sever e cases, the contents of the lagoon may need to be pumped or dredged out. Then the lagoon should be resealed and refilled with fresh water. - Schuyltheis (1997)

Effect of Garbage Disposers on Lagoon Septic Systems

Question: OK to use a garbage disposal grinder with lagoon septic systems?

(Jan 24, 2016) Jeremy said:
If our house has a lagoon (no septic system) would we be ok installing a garbage disposal on the kitchen sink?

6 June 2015 Jean said:
I have a lagoon system and no septic tank. Is using a garbage disposal still an issue? Thank you!

These questions were posted originally


Reply: check the BOD & garbage grinder discharge volume, keep solids out of the lagoon, add a septic filter, pump the septic tank more often, or forget the garbage grinder on private septic systems.

Thanks for the question, Jean. I researched the effects of garbage grinders on lagoon septics without much luck, finding only Marais 1996, cited below.

I don't know an authoritative answer; we might get an opinion from a septic engineer who has expertise in lagoon septic designs. If you know who installed your system could you ask them and let us know what you're told? I'll also continue researching the question.

Research I've read to date (cited below) suggests that you cannot dispose of garbage grinder waste into the lagoon itself and that extra costs would be involved (at the septic tank) to keep it out. Boadi (2002) provides a specific case report of the effects of urban waste pollution in a septic lagoon that was blocked in part by garbage but it's not clear that the garbage was other than large debris (not garbage grinder waste).

Meanwhile I *speculate* that there might be an effect on a lagoon system used for private wastewater treatment when we add the load of a garbage grinder or garbage disposer because the added organic matter increases the BOD on the system. (Biochemical Oxygen Demand).

But a more scholarly approach might be to calculate the volume of additional organic loading into the lagoon and to compare that with the volume of other (presumably human) organic waste entering the system. If the additional volume is a small percentage of the design percentage, it may be thus insignificant.

Palmer & Fallowfield give some guidance for an Australian lagoon septic system design but your lagoon's design criteria may well differ.

Significant is that the authors point out that gross solids may enter a conventional [Australian] conventional sewerage system while STEDS designs specify that gross solids are excluded from the network. (Palmer & Fallowfield 1999 p. 5).

Current oxidation lagoon design criteria provide for a five compartment lagoon with a 30 day detention primary compartment for BOD reduction followed by four 7.5 day compartments in series for pathogen reduction. - Palmer & Fallowfield (1999

These same authors describe a four-year septic tank sludge removal program for STED / lagoon septic designs as having been specified by the SA Health Commission (South Australia).

My opinion is that this is somewhat an arbitrary rule since septic tank size and wastewater loading volumes surely vary substantially from site to site.

See SEPTIC TANK PUMPING SCHEDULE for more empirically based approaches to deciding when to pump and clean the septic tankl. Keep in mind that even if you add a septic outlet filter and proceed to install a garbage grinder, you'll probably have to pump the septic tank more frequently as a result.

Watch out: If your garbage grinder's solid waste can be confined in the septic tank your system might meet the gross solids waste exclusion and the BOD criteria. But to do that, considering that garbage grinders produce a very fine slurry of kitchen waste, you'll need a high quality filter on the septic tank outlet, adding maintenance and cost to your system.

OPINION: given that good design is probably want to exclude grinder waste from the lagoon itself, and that keeping it out of the lagoon will add cost and maintenance requirements to your septic system, my view is that for private onsite wastetwater disposal it makes more sense to simply separate food waste in the kitchen ahead of the entire drain and waste system, simply disposing of it as solid garbage or food waste.

That makes sense even if you simply build a non-mainteained compost pile away from the septic system itself.

See GARBAGE GRINDERS vs SEPTICS for more about this argument.

We might find additional comments in some Lagoon Septic / Constructed Wetland Design research as well.

Research on the Effects of Garbage Disposer / Grinder Waste on Septic Lagoon Performance & Life

Odor complaints attributed to a Lagoon system

It is normal for a pr operly sized lagoon to have a musky odor during war mer weather after prolonged periods of cloudy weather , ice cover or temporar y over - loading.

If odors become of fensive, they may be con - trolled by broadcasting agricultural sodium nitrate or ammonium nitrate at a rate of 2 pounds per day over the surface of the lagoon until the lagoon turns green and the odor goes away .
- Schuyltheis (1997)


Wastewater Operating Levels in a Septic Lagoon

Maximum wastewater level: The wastewater level in a septic lagoon is described by a design high-water line in normal operations. In proper operation the lagoon will be operated so as to prevent the wastewater level from passing the one-foot freeboard required from the liquid level top to the top of the dike.

When wastewater levels are too high the property owner or maintenance manager should contact a septic pumping companyu to remove sufficient wastewater from the basin.

Minimum wastewater level: the lagoon wastewater level should be maintained at a minimum of two feet to assure proper operation. When water levels fall below that level water must be added.

As is done when starting-up a wastwater septic lagoon system, additional water may be added by the direction of rainwater, roof, or surface runoff temporarily into the lagoon. But do not leave those water sources permanently connected or the lagoon liquid levels will be too high or will overflow.

Periodically it will be necessary to remove solids from the lagoon, using the services of a professional engineer, registered health specialist, or master or certified pumper in accordance with federal, state or local regulations, e.g. in Nebraska, Title 124.

The lagoon should be equipped with a depth gauge giving visual indication of the liquid level at minimum operting depth (two feet) and the maximum design depth relative to the bottom or floor of the lagoon.

Typically (using NE code) the maximum operating depth for a septic wastewater lagon is 5 feet.

Water Requirements for Lagon Septic Systems:

During wet weather, you can prefill by temporarily diverting runoff from a roof or footing drain into the lagoon.

During drier weather, you may need to prefill by pumping water from the house water well or nearby pond.

Do not allow the lagoon’s compacted earthen liner to dry out. After this initial prefill, the lagoon will gradually be filled by the incoming effluent from the home.

Overflows from a Lagoon Septic System: Never allow the lagoon wastewater to leave your property, even during wet weather.

Grass planting on the lagoon banks and surround preventg erosion that can cause loss of lagoon water and also help dispose of effluent.

Sewage Lagoon Maintenance Inspection Checklist

The following lagoon inspection checklist items are adapted from the Australia Department of Health citation as well as others found at LAGOON SEPTIC DESIGN & MAINTENANCE REFERENCES


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