Leach field and dispersal field types and technologies

Septic systems are specifically designed for the site and soil conditions of the project.

Every septic system is different. As such, it is important to consider all (or as many as possible) aspects of the site conditions when developing new or replacement septic systems. This page discusses the dispersal field component of the septic system. Simply click below if you would like to read about other aspects of the septic system, such as the septic tank or key maintenance items. 


Following the site investigation phase, a suitable septic system dispersal field type needs to be selected. Some factors that our engineers consider are soil type & depth, topography, parcel size, design flow, wastewater strength, regulatory restrictions & regulations, and owner & installer preference. Scroll below to read about the benefits and setbacks from various types of leach fields. If a dispersal field type you've heard of isn't mentioned, let us know and we can discuss its applicability to a practical application. 

Standard conventional gravity leach field

Tried and true for appropriate sites

Probably the most commonly known leach field type is the tried and true conventional gravity trench. For sites with plenty of space, suitable soil depth and type, and without significant constraints, conventional gravity leach fields are most appropriate. 


Treatment train:

The typical treatment train of a gravity leach field for a dwelling: dwelling raw sewage gravity flow to a septic tank gravity flow leach field that is dispersed by gravity flow. Some common distribution types to multiple leach lines include pop-over serial distribution, drop box serial distribution, distribution box, interconnected grid.


Constraints addressed: 

Our engineers address site constraints by use of gravity leach fields by the following ways. Consideration is given to setbacks (creeks, buildings, driving surfaces) from the beginning site reconnaissance phase. During soil investigation it is important to consider all possible available area if insufficient soil depth or type is found in one area. Often unsuitable area is found in one location, then investigation is done in another area, finding suitable soil depth/type.


Lifecyle cost:

Cost is always a consideration, but lifecyle cost is the real consideration. As in every septic system maintenance is important. To have the lowest lifecyle cost on any engineered work it is important to properly maintain the work. Click here to read about septic system maintenance. 

Pressure distribution leach field

A great dispersal technique for appropriate sites.

Sometime slopes, soil type, soil depth, site geometry constraints limit the ability to install a conventional leach field. In some cases a pressure distribution leach field is the solution. While the technology used is only slightly more than a conventional leach field, major rewards & advantages are seen from the use of pressure distribution. 


In most cases, a pressure distribution leach field is essentially a conventional trench with pressure flow. The main benefit of a pressure distribution leach field is the even effluent distribution to the entire leach field. What's the big deal you wonder? Even effluent distribution allows for very predictable use of the entire leach field. This allows for justification for use of steep slopes, less than ideal soil type and depth, and overall a significantly more predictable leach field.

More dispersal field types explanations coming soon

Check back soon, we're currently updating our website. Soon you'll be able to see more explanations of different septic system leach field types. In the meantime, give us a call to find out more.

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