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

  • LAGOON SEPTIC MAINTENANCE - CONTENTS: what are the maintenance requirements for a septic lagoon system to get the maximum life, minimize odor complaints & keep the system working? Additives, cleaning, vegetation, water levels & odor complaints are discussed.
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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

Reader Question:

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.

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.

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

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 at TOILETS, DON'T FLUSH LIST

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)

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 leve 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. Also see Surface water control discussed below.

Lagoon Wastewater Treatment System Installation & Maintenance References & Guides


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