Not an Either/Or Proposition

Both the onsite system and the municipal sewage treatment system have their place

Question:

Would you explain the many different reasons why onsite septic systems are better for the environment than municipal treatment plants, and also the advantages of onsite septic systems?

Answer:

First, there should be no conflict between the use of onsite sewage treatment systems and municipal sewage treatment systems. This statement assumes onsite sewage treatment systems are properly designed, properly installed and properly maintained. It also assumes the same is true for municipal sewage treatment systems.

Many problems concerning the use of onsite systems arise because some individuals believe municipal treatment is the answer to all sewage treatment problems. This seems to happen often where waterfront properties are concerned.

ON THE LAKESHORE

As an example, a federally supported study was made of a lake in Minnesota having eutrophication (excess fertility) problems. Many weeds and algae were growing in the lake. (Eutrophication is defined in the Encarta Dictionary as “the process by which a body of water becomes rich in dissolved nutrients from fertilizers or sewage, thereby encouraging the growth and decomposition of oxygen-depleting plant life and resulting in harm to other organisms”).

A similar definition of eutrophication was probably used to evaluate this lake’s problems. Since sewage was mentioned as a cause, septic systems were judged to be the problem. A sewer line was constructed, at high cost, to a municipal treatment system, several miles away.

The research study continued to take lake water samples to evaluate the fertility. The samples showed eutrophication did not decrease with the elimination of onsite systems. The conclusion was that excess fertility was caused by nutrients being washed in from gardens, leaves, grass clippings, street runoff, and green lawns fertilized and mowed down to the water’s edge.

The onsite systems on those lakeshore properties could have remained in place doing an adequate job of sewage treatment.

In the October 2009 issue of Pumper, an article told of sewage problems in a small rural Iowa municipality with about 40 homes. The most economical solution to their sewage treatment problem was installation of properly designed onsite sewage treatment systems.

CLUSTER SYSTEMS

In this case, economics was the deciding factor. Onsite sewage treatment systems were less costly to install and maintain than a municipal sewage treatment system. And the onsite systems will do an excellent job of properly treating the sewage from these homes.

A benefit of individual onsite systems is that effluent is distributed over a large area. Each system might be on a half-acre or larger lot. The sewage tank effluent is treated by a soil treatment system on each lot. The disease-causing bacteria are destroyed as the water percolates downward. The percolating water carries a small amount of nitrates, but far less than the amount commonly applied to the lawn where the system is located.

A number of years ago, a study was made by a federal agency to determine the effect of individual sewage treatment systems on the water table in an area with sandy soils. The Anoka Sand Plain, north of Minneapolis, was the study area. The research identified nitrogen from an onsite system separately from the nitrates used in commercial fertilizer applied to lawns.

The study showed a small amount of nitrate was leaching down to the water table. The nitrate was identified as coming from lawn fertilizer and not the onsite sewage treatment systems.

There is a definite trend today for cluster onsite systems being designed and installed, collecting sewage tank effluent from a large number of homes built on relatively small lots. This effluent is applied to a relatively small area compared to an individual soil absorption system on each lot. In my opinion, the cluster systems will have a potential for causing an increase in nitrates in the ground water.

The reason for cluster systems is basically economic: Less area is needed for the total housing development. There is, however, the benefit that individual homeowners do not have any responsibility for maintenance of their onsite system.

POPULAR MISCONCEPTION

When an individual onsite system fails because of excessive water use or lack of maintenance, there is the “popular” misconception the system is causing pollution of the ground water. While there is a health hazard from sewage surfacing from a failing onsite system, there is no pollution moving downward. Actually, less liquid moves downward from a failed onsite soil treatment area. The biomat has become thicker because of more sewage solids in the effluent, likely caused by a septic tank that hasn’t been cleaned and pumped as needed.

The thicker biomat is doing a better job of slowing effluent flow into the underlying soil. In fact, the effluent flow has been slowed so much that some is coming to the surface. The failed onsite system is not causing groundwater pollution, as is commonly claimed by the misinformed.

When a municipal sewage treatment system discharging treated sewage into a nearby stream fails, the discharge is immediately causing pollution. Granted, this rarely happens today. But the potential is there.

An onsite system must be properly designed using accurate information about site soil conditions. The system must be installed according to the design specifications. The homeowner must use the system properly and provide adequate maintenance. In my opinion, such a system has a longer life for adequate sewage treatment than most municipal systems. The onsite system is also an environmentally sound sewage treatment system.

BETTER OVERSIGHT

Both the onsite system and the municipal sewage treatment system have their place. And both of the industries must recognize this fact.

I am pleased with news that more states review and update their onsite sewage treatment system rules. More states have educational seminars and workshops for onsite sewage treatment professionals. With sound rules and better-informed onsite professionals, onsite systems are designed, installed and maintained better.

I hope onsite sewage treatment systems are being acknowledged more often today as the most appropriate answer to many sewage treatment problems.



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