Knowledge of the land key to a safe and efficient septic system
June 15, 2006:
Septic system problems can be minimized by making sure a system meets the needs of the farm and is a good match for the environment around it, say those on the forefront of on-farm environmental stewardship in Alberta.
"Ask the experts, and they will tell you that any given septic system is as unique as the land it services," says Therese Tompkins, program director with the Alberta Environmental Farm Plan (AEFP) Company, which delivers the Environmental Farm Plan (EFP) program in the province. "Soil quality, land gradients and the number of people living on the property are all factors to consider when deciding the kind of septic system to install."
An ongoing survey administered by AEFP reveals that household wastewater management is considered one of the top five environmental challenges among producers. An EFP is a free, voluntary assessment of an agricultural operation’s environmental strengths and weaknesses.
Pressure-fed and gravity-fed systems are the two common choices when it comes to septic system discharge, says Joe Petryk, a senior field inspector with Alberta Municipal Affairs. "With gravity-fed systems, the sewage flows out of the tank and into a lower-elevation field, which takes the effluent underground through a series of pipes and allows it to be absorbed by the infiltration area within the field.
"Pressure-fed systems, meanwhile, use a pump set in the effluent chamber that forces effluent throughout the treatment field. Because the effluent doesn’t mass in one place, we generally recommend pressure-fed systems."
Making sure the septic tank size is adequate for the farm’s needs is another crucial consideration, says Petryk. "To get a general idea of the size of tank required, multiply the number of bedrooms by the number of people per bedroom and then multiply the result by 340. For example, two persons in a two bedroom home would be two multiplied by two multiplied by 340 to equal the number of litres required."
Making the right decision on what kind of treatment system to use depends largely on soil profile. Currently, the Private Sewage Standard of Practice accepts a "soils percolation test" or a "soils particle or grain size analysis test" done by a lab to arrive at the acceptable effluent loading rate of a field or mound. Of the two tests, the latter is usually more accurate, says Petryk.
Open discharge systems are the easiest septic systems to maintain, says Petryk. "If a landowner already has an existing septic tank system, then management largely involves keeping track of solid waste build-up and deciding how often to pump it out."
In some instances, when a site is faced with several design constraints, the only option may be to install a holding tank. These tanks are available in various sizes and store the sewage until the tank is full. The sewage then needs to be removed from the tank by a sewage pump truck and disposed of at an approved disposal site, usually a municipal lagoon. In some cases, land spreading is allowed under the approval process established by Alberta Environment.
In subsurface fields, wastewater is discharged and the aerobic treatment of wastewater takes place, says Petryk. They are generally most appropriate in loamy soil conditions. Treatment mounds are best used in situations where the subsoil is not suitable for absorbing effluent.
Lagoons are best for land with poor soil. Lagoon maintenance involves monitoring the collection pit at the bottom of the lagoon to make sure solid waste isn’t building up too high, says Petryk.
Septic systems are an important consideration in the overall sustainability of a farm or ranch, says Tompkins. More information on septic systems is available in a feature article with Joe Petryk in the AEFP Journal, AEFP’s Web magazine, at www.albertaEFP.com. Information is also available at the Alberta Municipal Affairs Web site at www.municipalaffairs.gov.ab.ca/ss_index.htm or by calling toll-free 1-866-421-6929.
Through the Agricultural Policy Framework (APF), the Government of Canada provides major funding to the EFP program in Alberta, with the Government of Alberta providing additional in-kind support services to help the agricultural sector develop and implement Environmental Farm Plans.
Additional support has been provided by the Agriculture and Food Council, through the Agriculture Environmental Stewardship Initiative, the Alberta Environmentally Sustainable Agriculture Council and various ministries of the Government of Alberta. Contributions have also come from more than 100 local municipalities, businesses and agricultural organizations.