The dreaded lagoon, most people do not like this option when it is given to them. Most people feel that the lagoon will smell and the thought of open water is unattractive feature. The lagoon can be a person's best friend or the worst enemy to some. The positive points of the lagoon are there is no smell if the work is done correctly. The way the lagoon is designed the effluent leaves the home to the septic tank where it gets pre-treated, then passes through a filter to the bottom of the lagoon. The reason this pipe exits on the bottom of the lagoon is the gases that you would smell get trapped in the water of the lagoon keeping the system from smelling. If the water does reach the overflow point it leads to overflow chambers (most of the time) to keep the system underground. If your ground has high clay soils or massive clay, the lagoon is perfect for those types of soil. If you have a large lot the lagoon can be hidden from site and will not need much maintenance (out of site out of mind). Most commonly the lagoon is one of the most inexpensive types of systems (cheaper the better). Now the bad part of the lagoon, if you have a small lot it will be very close to the home. It requires a 6' fence around the lagoon to keep animals and kids from getting in the water, (very steep slope on sidewalls) if they get in they may not get out. Also the lagoon may be difficult to put in on rocky lots, due to the depth required to place the lagoon.
Advantages
- Space efficient compared to other systems.
- Cost efficient and easily installed.
- No odor or mosquito problems.
- Relatively low maintenance.
- Best working system, if designed properly.
Disadvantages
- 6' fence required and locking gate.
- Open water and the thought of smell may be unattractive.
The leaching chamber is the modern answer to the question, "I have limited space, what do I do now!" The chamber system allows for a nice reduction on the lateral lines from the standard system of rock. The leaching chambers range in size allowing for different design choices; the chambers come in sizes of 1', 2' and 3' wide. The chamber system can be place like the rock system allowing for equal flow and hillside distribution and long lateral lines. The chambers can be place side by side creating a chamber bed system that gives a greater reduction to the septic size. Although the chamber beds allow for the reduction in lateral size it can only be used on lots with less than a 5% slope for the system area. The chamber system only requires 6" of cover soil over the chambers and no barrier material (straw, hay, cloth lining) so it help reduce the cost of the system as well.
Advantages
- Uses less space than the rock system.
- Reduction in cover soil needed for the system.
- Easy to install.
Disadvantages
- Limited slope restrictions
- Vehicle traffic over the chambers is prohibited to prevent soil compaction.
Constructed wetland cells are a newer system that allows some unusable lots to be used. The wetland cell is primarily a lined box with plants and overflow lateral fields that consume the rest of the effluent. The system generally consists of a primary tank with a large filter, control box (maintain water level), wetland box and the overflow lateral field. The effluent leaves the home to the septic tank for pre-treatment. The filter keeps most of the solids in the tank, the effluent moves to the wetland cell where plants and evaporation remove most of the bacteria and effluent. If the box does have excess effluent it moves to the control box and then the overflow lateral field where the rest of the effluent is treated.
Advantages
- Can be placed on irregular or segmented lots.
- May be placed in areas with shallow water tables, high bedrock or restrictive horizons.
- Requires less lateral field length.
- Decorative appeal.
Disadvantages
- Requires a higher level of maintenance.
- May be more costly
- Unknown lifespan of system.
The rock system is the most common type of septic system available (septic installers are very familiar with this system). The rock and pipe system operates very easily; the effluent leaves the home to the septic tank where it receives pre-treatment and moves to the first distribution box (if non-pumped system). If the system is an equal flow distribution type then the effluent will go to all the lines at one time spreading the effluent over the entire field allowing for faster absorption. If the system is a hillside distribution type, then the effluent will go to the first box and then the first line. Once the first line fills to the maximum level the effluent will move to the next box and the next line. This will continue until the end of the lines or the effluent is absorbed.
Advantages
- Can be used on either level or sloping lots.
- Most common type of septic system.
- May be used with all types of distribution boxes.
- Can be curved around hillsides to allow for installation.
Disadvantages
- Typically uses the most space of all the systems.
- Requires more topsoil to cover the system then others.
- Must have a minimal soil depth of 18" for a shallow installation of this type of septic system.
A mound system is a soil absorption system that is elevated above the natural soil surface in suitable / unsuitable soil conditions. The main components of the mound system are the septic tank or pre-treatment unit, the dosing tank or pump tank and the elevated mound system. The mound system works like this, the effluent passes from the home to the septic tank where it receives pre-treatment and goes through a filter to the pump tank. Once the pump tank is at the appropriate level the pump will turn on and pump the effluent out to the mound system. The mound system is a series of pipes with small holes in them allowing the effluent to spread around the entire mound a one time, this allows for faster evaporation and cleaning of the effluent.
Advantages
- The mound may be used in high ground water table areas, bedrock, high clay soils and high pan restrictions.
- Very space efficient compared to other septic systems.
- Can be used in most climates.
- Almost an underground system. (Can be hidden from view)
- Relatively low maintenance.
Disadvantages
- Cost, Higher cost than other systems.
- Requires a pump tank and pump added to the system.
- Regular inspection of the pumps and controls is necessary.
- System may be difficult to design.
A curtain drain is a drain used to intercept water moving though the soil. The term "perimeter drain" describes a curtain drain that surrounds an area, making a complete circuit. Perimeter drains are sometimes installed around septic systems in order to remove outside water influences from the septic area to prevent a septic system from failing. The determination to use a curtain drain stems from the mottling in the soil found at the time of the site evaluation. Mottling is a term describing a change in the soil; spots or blotches of different color or shades of color interspersed with the dominant color of soil. This means little gray color mixed into the darker color soil and shows that water stays in the soil.