Secondary treatment plants are an upgrade to the conventional septic tank. Basically they treat the sewage inside of the tanks and reduce the strength of the effluent by 85% which allows it to be discharged into a smaller septic field area.
This type of system is specified for ecologically sensitive areas or areas that have poor soil conditions or high water tables.
The Pro Flo system is the type of secondary treatment plant that we recommend to our clients. Within 24 hours of the sewage entering the tank the product is purified to the point that it is a crystal clear liquid that could be used for the underground irrigation of plants, trees or lawns.
This system is very easy to operate, is NSF 40 compliant and is a class 1 treatment plant. Like any secondary treatment plant, this plant requires annual maintenance by a certified technician. The Pro Flo system is the most economical to maintain which make it a superior product to specify.
A conventional septic tank is the concrete vessel below the ground near the house. It is here that all the wastewater and materials that are flushed down the drain are deposited.
In a conventional septic tank there are 2 compartments. The first section is the Working Compartment (aka Trash Tank) and it is here where the solids in the wastewater settle to the bottom (Sludge) and the greases and fats float to the top (Scum) which leaves grey water in the middle. This process of separation plus the biological digestion of bacteria collectively support a major portion of the sewage treatment. The grey water which is the cleanest (in the middle of the tank) is allowed to migrate into the next compartment via a plumbing system. This keeps all solids contained within the Working Tank.
The second compartment is the Dose Tank. This is where the effluent is either pumped or siphoned out to the septic field. This tank may only use 30% of the total gallonage of the entire septic tank. Very little biological breakdown occurs in this compartment. The Dose tank will have a high water alarm set up to notify the homeowner if the pump or siphon system fails. This is mandatory and has saved many homes from a sewage backflow issue occurring in the basement.
It is critical that the septic tank be sized properly to meet or exceed the peak daily flow rates created by the household. An undersized or poorly maintained tank will not be capable of processing the effluent within the Working Chamber. This means that suspended solid materials will be forced into the Dose Chamber and sent to the septic field. This results in plugging and overloading the soil structure and eventually saturating and flooding the system. We recommend over sizing the septic tank as it is the main processing component in the septic system.
Since the new regulations came into force, gravity or syphon tanks and gravity fed septic fields are almost non existent. The code requires an inline filter on all septic tanks which are almost impossible to install without critical failures on a gravity system. Gravity fed septic fields receive all the sewage water (effluent) by being dumped into one area. This part of the field becomes waterlogged and plugged and the effluent migrates slowly along the trenches until it can be displaced. This system is prone to failure on today’s modern homes as the water usage is significantly higher than it was on Grandpa’s 1000 sf farm house.
The effluent is pumped out of the Dose Tank and through an in line filter system using a high capacity pump. The effluent flows through PVC piping system to the excavated field area. The entire surface area of the field receives an equal dosage of effluent which compared to a conventional gravity fed system, eliminates overloading the first section of any lateral. These types of septic fields are more efficient in processing the effluent due to the consistent effluent distribution.
The At Grade design is identical in component structure to the Pressure Distribution System except that the laterals are not buried into the ground. This system works well for the following applications: areas that have marginal soil structure for effective effluent treatment and areas which do not want the natural trees removed to accommodate a conventional buried septic field. Very easy access to all field components for repair or maintenance.
The mound has the same components as the Pressure Distribution system or the At Grade system. The laterals are constructed on top of a thick sand layer which is imported and placed in the field location. This septic system is used where the natural soil structure will not support a septic field operation. It can accommodate a higher daily effluent flow rate into a surface area that is smaller than a conventional field.