The type of wastewater treatment system specified is contingent upon the soil inventory onsite – soils dictate the type of system required.
Primary Treated Effluent Systems
Conventional two compartment septic tank and a septic field.
Secondary Treated Effluent
Useful when there is less than 5 feet of suitable soil for the effluent to travel through. Min of 3 feet.
Sand Treatment Mound
Useful in high water or shallow restrictive soil layer conditions.
LFH At-grade Treatment Systems
Requires secondary treated effluent and to be installed in a forested area.
Proper soil analyzation is critical to the success of your septic system. A recent publication by Onsite Installer magazine listed the number one cause of failed systems to be improper soil identification. Over the last decade, Daniel has devoted most of his time to studying the soil inventory in most areas of Alberta. This gives customers security that their septic design will be designed correctly for the soils at their sites.
The Maximum depth of a trench is 3 feet. For Primary treated effluent (wastewater from a septic tank) the code requires a minimum of 5 feet of suitable soil below trench bottom to effectively treat the effluent. For Secondary treated effluent (from a treatment plant or a mound) the code requires at least 3 feet of suitable soil below trench bottom to treat the effluent. In cases where there is approximately 3 feet of soil or less, as measured from native ground surface to a restrictive layer a pressurized sand treatment mound is typically prescribed.
For further information view the Alberta Municipal Affairs website: Homeowner Information - Advice for Selecting a Private Sewage System.
This type of septic system comprises a conventional two compartment septic tank and a septic field.
The sewage from the home travels through the plumbing of the facility and enters the first compartment of the septic tank. This is where the solids within the wastewater are allowed to settle to the bottom of the tank (sludge) and the greases and soap residual can float to the top of the wastewater and creates a scum layer. This first compartment of the septic tank is crucial to being sized correctly for the facility so that there is sufficient retention time to allow the solids to settle and greases to float. Physical separation is the only treatment process that occurs in the first compartment of a septic tank. Very limited biological digestion occurs in the septic tank, as it is an anaerobic environment. This compartment needs to hold the expected volume of wastewater from the home for a minimum of 24 hours to allow the settling/floating process to occur, to protect the soils from becoming plugged with solids and grease.
At this time Alberta requires ALL wastewater from homes to be sent to a holding tank or septic tank. There is no differentiation between black water (toilet water) and grey water (laundry/shower water). Although grey water contains less solid waste than black water; it still contains viruses, and bacteria that can pose a human health risk.
The middle section of the working chamber contains the cleanest effluent. The effluent travels downstream to the second compartment (dose chamber/tank) for further settling and to be contained until a specific volume can be dosed out to the soil based treatment area. Once the wastewater from the home has been retained for a minimum 24 hours, it is considered to be primary treated effluent. Final treatment of the effluent takes place in the soils.
Primary treated effluent can be distributed to the soils via a trench type system when the site and soil conditions at the site allow. This includes traditional pipe and washed drain media type systems and chambers (plastic domes) as well. The distribution of the effluent can be either by gravity or pressure distribution. Pressure distribution is highly recommended as it ensures all of the usable soil inventory receives wastewater each time the pump cycles. Another benefit is the trench bottom area may be reduced as the code allows loading rate factors if pressure distribution is incorporated into the design and provided the soils can have an increased loading rate.
Various manufacturers have treatment plants that treat the sewage prior to discharging it into the soil based treatment area. Secondary treated effluent is of a higher quality than primary effluent. This means it contains less solid matter and less organics, and therefore reduces treatment demands on the soils. Some types of soils require secondary treated effluent only. The two major types of treatment plants are as follows:
* ALL Secondary treated effluent requires pressure distribution + timed dosing with data logging capabilities. Examples of various secondary treatment plants available in Alberta can be provided by D&S upon request.
A finished sand treatment mound. Here the landscaper has included some rock gardens and trees to tie the treatment mound into the final landscape design.
LFH At-grade septic field installation. Photo compliments of Gray line Contracting Ltd
LFH At-grade during and after construction... nicely blended into the landscape. Photo compliments of Alaqua Projects Inc.
The Forest Floor website
Since humus forms are comprised of a group of soil horizons located at or near the surface, which have formed from organic residues (separate from or mixed with ... There are two groups of organic horizons– those that are formed in relatively well-drained conditions (LFH) and those that are formed in poorly drained... more