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Our licenced Professional Engineers have extensive experience in designing onsite septic systems in Ontario.
Our licenced Professional Engineers design variety of advanced, innovative, predictable, permanent, robust, cost-effective, compact, low energy, low maintenance, visually subtle, and efficient onsite septic systems for off-sewer developments in Ontario.
Our septic system designs meet requirements of Ontario Building Code and Ministry of the Environment and Climate Change, and offer the most affordable, long-lasting site-specific septic system design. Inappropriate septic system design, bad construction practices, or poor maintenance can all lead to septic system failure.
Properties in rural areas rely upon onsite septic systems for their sewage disposal. In the 1970s, the responsibility for overseeing the installation of septic system systems in Ontario was transferred from the Ministry of Health to the Ministry of Environment. Afterwards, regulations governing private onsite septic systems were then transferred from the Ministry of Environment to the Ministry of Municipal Affairs and Housing and subsequently incorporated into the Ontario Building Code.
Part 8 of the Ontario Building Code governs the design, construction, operation and maintenance of onsite septic systems up to a capacity of daily sewage flow of 10,000 litres on one individual lot. The local municipality’s Building Department examines septic permit applications for proposed construction of a septic system, issues septic permits for construction of septic systems, and does inspections for septic systems regulated under the Part 8 of the Ontario Building Code.
The Municipality / Health Unit Officials regulate the design, construction and approval of on-site private sewage systems with a design capacity of less than 10 000 litres per day.
The two main factors that dictate the size and complexity of a septic system are the maximum amount of wastewater that the building could produce on a daily basis, and soil/site conditions.
Geotechnical investigation including proper soil testing ensures the septic system meets the specific requirements of a site. Enlisting the help of a qualified and registered professional engineering firm is a key element to the successful septic system design.
Our licensed professional engineers design onsite septic systems that will work best for the property based on the specific site-specific characteristics including:
The rate at which the wastewater will be absorbed into the soil is called a "T" time. "T" time is equal to the number of minutes it takes for the water level to drop per cm in a water filled hole in the receiving soil. In sandy soil a typical "T" time is less than 10 (meaning it took less than 10 minutes for the water level to drop 1 cm in the water filled hole). But in sandy loam soil the "T" time could be 20 or more because the smaller soil particles are slowing the rate of absorption. The worst soil though is clay where the "T" time is typically well over 50 because clay particles are so fine and tightly packed.
Once the maximum amount of wastewater that the building could produce on a daily basis (Daily Sewage Flow) and the "T" time is identified, we can then figure out how large the septic system has to be. Each type of system then has a different equation to be used to figure out the size of the septic system.
Ontario Building Code Design Standards
General Requirements
Site Evaluation
(1) A site evaluation shall be conducted on every site where a new sewage system is to be installed.
(2) The percolation time shall be determined by,
(a) conducting percolation tests, or
(b) classifying the soil according to one of the following methods,
(i) the Unified Soil Classification System as described in MMAH Supplementary Standard SB-6, “Percolation Time and Soil Descriptions”, or
(ii) the Soil Texture Classification as described in Chapter 3 of USDA, “Soil Survey Manual”.
(3) Where the percolation time is determined by a percolation test, there shall be a minimum of 3 locations selected, suitably spaced to accurately evaluate the leaching bed area, with the highest percolation time of the tests being used.
Minimum Clearances
For Septic Treatment Units
Structure 1½m
Well, Lake, Pond, Reservoir, River, Spring, Stream 15m
Property Line 3 m
For Septic Distribution Piping
Structure 5m
Well with a watertight casing to a depth of at least 6 m 15m
Any other well 30m
Well, Lake, Pond, Reservoir, River, Spring, Stream 15m
Property Line 3m
On-site private septic system has two basic parts: a septic tank which receives the untreated sewage and in which solids settle out, and a leaching bed (tile bed) through which the liquid waste portion of the sewage is dispersed into the soil. The main function of the septic tank is to allow solids to settle and to let clear effluent flow to the septic tile bed. Biological reactions within the septic tank will break down some solids to liquids and gases, but the retained solids will eventually accumulate in the septic tank. Only clear liquid waste should be discharged from the septic tank to the septic tile bed. This liquid waste will then undergo further biological break-down and treatment. To ensure efficient operation of the entire septic system, it is important that the sludge, scum and solids which can accumulate in the septic tank do not enter the septic leaching bed (tile bed). The septic tank should be inspected by a licensed professional at least once every two years and the septic tank shall be pumped out when necessary.
Design of an onsite septic system for new construction is always a challenge because of the very limited area available for the septic system due to the required minimum setbacks from the well, property lines and the proposed structure.
Advanced septic treatment systems are required when:
Septic tanks do not use oxygen as part of the septic treatment. This is known as anaerobic septic treatment. Advanced septic treatment units use oxygen to enhance septic treatment. This is known as aerobic septic treatment. Aerobic septic treatment units treat septic sewage by adding air. Aerobic septic treatment units inject and circulate air so that oxygen-dependent bacteria can thrive. The bacteria break down organic matter, reduce pathogens and transform nutrients (e.g., ammonia to nitrate). Aerobic septic treatment units often have a pre-treatment septic tank where the scum and solids are separated and stored before the effluent is passed to an aeration chamber. At the aeration chamber, air is added to the effluent, which allows the bacteria to feed on the contaminants thereby producing cleaner effluent. Generally, aerobic septic treatment units are classified based on the status of bacteria in the wastewater within the septic treatment unit. Bacteria are either suspended in the liquid or attached to some media. Aerobic septic treatment units require air compressors and in most cases pumps, and use an area bed or shallow buried septic trench for final distribution and treatment of septic sewage.
In suspended growth septic treatment units, wastewater flows from the pre-treatment tank into the aeration chamber where an air compressor and air diffuser supply oxygen and mix the liquid waste. The air keeps the bacteria “suspended” or floating in the liquid waste. It does not attach to any surface. The oxygen supports the growth of the bacteria and other micro-organisms that break down the wastewater and solids. The effluent then flows into a shallow buried septic trench or area bed. Suspended Growth Treatment Units presently used in Ontario include, Aquarobic, Biocycle, Clearstream, Norweco Singulair, and WSB.
In attached growth septic treatment units, wastewater from the pre-treatment septic tank flows into an aeration tank that contains pieces of plastic or other synthetic material. Attached growth units rely on oxygen-dependent bacteria to break down wastewater and solids similar to suspended growth units. The difference is that attached growth units let the bacteria attach, grow and thrive on the synthetic material (e.g., plastic shavings, balls, etc.). An air diffuser provides continuous aeration around the synthetic material to enhance bacterial activity and septic treatment. Some attached growth septic treatment units require an air compressor. The effluent then flows to a shallow buried septic trench or area bed. Attached growth septic treatment units presently used in Ontario include Bionest, Bio-Microbics — FAST, Nayadic, and Rotordisk.
The BIONEST septic system is an advanced generation of onsite wastewater treatment systems. It is a biological process consisting of an extended aeration fixed film reactor. Biomass (good bacteria) develops and firmly attaches to both sides of the BIONEST ribbon shaped polymer media. The high population of bacteria and the support offered by the media for their growth provide the reactor with an outstanding performance level and resistance to hydraulic shock (peak flow). Unlike activated sludge systems which require daily sludge ‘wasting”, the extended retention time in the BIONEST septic system minimizes the biological sludge production. The BIONEST septic system is designed to ensure sufficient opportunity time for the biomass to remove pollutants. The major portion of the reactor is aerated through linear air pumps and fine bubble diffusers, which provide turbulent conditions to ensure enhanced septic treatment. Multiple pumps are used to supply air to the reactor allowing for redundancy, thus ensuring continuous septic treatment even during maintenance or failure of one or more air pumps. In the remaining portion of the BIONEST reactor, a high level of dissolved oxygen further assists in the oxidation process, in a calmer environment.
This calm zone ensures that no solids escape the reactor and that the final effluent is extremely clear. The BIONEST septic system incorporates a recirculation loop that makes the system a multi-pass process bringing performance to a very high level. Filtration units utilize trickling filter technology. Wastewater flows to a pre-treatment septic tank. Wastewater then flows from the pre-treatment septic tank into the filtration unit that is filled with materials such as peat moss, sand or a synthetic medium. As the wastewater trickles or percolates down through the filtration unit, a bacterial slime grows and thrives. Typically, trapped air fills the voids in the medium and encourages aerobic conditions where bacteria break down the sewage as it slowly moves through the filter medium. The effluent then flows to a shallow buried septic trench or an area bed for final distribution and treatment in the soil. Filter beds can be made verifiable by installing underdrains, which would keep the sand free-draining and aerobic. High-quality effluent from filter beds, peat or foam filters can then be placed in a “shallow area septic bed” for low-risk disposal. The shallow area septic bed technology, used in Ontario since 1994, affords a two-stage filtration septic treatment train. The “roughing filter” of sand, peat or foam removes ~95% of the organics and >99% of E. coli.
The second “polishing filter” is the fine sand layer in the shallow area septic bed that removes the remaining E. coli for a total of 99.9993% removal before entering the natural environment. The soil and the groundwater are both protected, and health risks are minimized. The double safeguard of septic filtration treatment followed by filtration disposal is similar to the preferred “multiple-barrier” approach to drinking water safety. The multi-barrier approach or defence in depth has been an approach which has long been used by the drinking water industry to provide safe and secure supplies of drinking water. The single biomat barrier in soil based septic systems does not provide the safety of the multiple-barrier approach.
Synthetic Media Filter Septic Treatment Units presently used in Ontario include Waterloo Biofilter and Orenco AdvanTex. The Waterloo Biofilter is an aerobic trickling filter that uses an absorbent synthetic filter material developed by researchers at the University of Waterloo and first installed in Ontario in 1991. Septic tank effluent is applied intermittently to the top of the filter media.
The synthetic media is a support for microbiological growth, and these microorganisms are responsible for the aerobic breakdown of the wastewater. The core of the Waterloo Biofilter system is a synthetic, absorbent filter medium that is configured as a free draining, attached growth, biological trickling filter to treat sewage and process wastewaters.
This patented, engineered Waterloo Biofilter medium is consistent in its physical properties and has been optimized to:
The absorbent Waterloo Biofilter filter medium creates an ideal environment for microbial attachment. Beneficial bacteria colonize the interior surfaces of the absorbent Waterloo Biofilter filter medium where they are protected from predators, desiccation, and freezing. These microbes degrade and oxidize organic pollutants, coliform bacteria, ammonium, and other contaminants as the wastewater is retained in the absorbent Waterloo Biofilter filter medium by capillarity. Air passively circulates throughout the absorbent Waterloo Biofilter filter medium providing an aerobic treatment environment without the need for forced aeration. This attached growth process (also referred to as a fixed film process, intermittent filter, packed bed media filter, or percolating filter) outperforms activated sludge or suspended growth (suspended sludge) processes with lower energy requirements, fewer moving parts, simpler operation, less maintenance, and a better ability to handle shock loads of chemical addition or hydraulic overloads. Waterloo Biofilter is proven in frigid -50°C temperatures, treating cold sewage with influent temperatures as low as 3°C. Compared to other media-based trickling filters, the Waterloo Biofilter does not slough off microbes in the form of aerobic sludge, maintains high treatment levels even in very cold climates, has longer retention times, and can accept much higher organic and hydraulic loads without plugging. Waterloo Biofilters consistently provide tertiary, sand filter quality effluent (< 10 mg/L cBOD & TSS) that is clear and odourless. Highly treated effluent is easily and safely dispersed back into the soil via small, shallow disposal beds or trenches, or can be reused onsite for purposes such as irrigation, truck washing or toilet flushing.
Peat Filter Septic Treatment Units presently used in Ontario include Premier Tech — Ecoflo and Puraflo. The Ecoflo Biofilter is a trickling filter that uses peat to treat wastewater. The Ecoflo Biofilter consists of an open-bottomed fibreglass shell full of harvested peat. Effluent from a septic tank is delivered by pump or by gravity (depending on relative elevations) to the top of the peat media. Wastewater percolates downward through the peat and then through the infiltration zone, which consists of 200 mm of clear stone & 300 mm of clean sand. After moving through this infiltrative zone, wastewater infiltrates into the native soils. The peat acts both as a place for aerobic bacteria to anchor and treat wastewater as it passes through the filter and as a physical filter. Some limited chemical reactions are also achieved. Aeration of the unit is passive, i.e. there are no blowers or fans to enhance air movement through the peat. The peat must be replaced approximately every 8 years.
Sand Filter Treatment Units presently used in Ontario include Orenco.
Advanced septic treatment systems are very effective in treating septic sewage. With cleaner effluent leaving these advanced septic treatment systems, the size of the soil component (leaching bed) that is needed to complete the septic treatment is smaller than for those using septic tanks only. Advanced septic treatment systems could use one of two small leaching bed systems that are currently approved or authorized in Ontario: shallow buried septic trench and area bed. Advanced septic treatment systems can be used with a variety of above ground and in-ground distribution options and offer several unique final distribution options.
Advanced control panels, auto-dialer alarm systems, and remote monitoring service make operation of the septic system simple and efficient.
Effluent Filter
An effluent filter installed at the outlet of the septic tank, dramatically improves the quality of effluent being discharged to the leaching bed, effectively extending its life. The addition of an effluent filter to all systems is strongly recommended. Sewage enters the first chamber of the septic tank through an inlet baffle or tee. Most of the larger particles settle out and the effluent enters the second chamber. The second chamber (much smaller than the first) further enhances the settling process. If flows are heavy at times, solids can pass through both compartments and enter the leaching bed. The effluent filter minimizes this. Effluent filters in accordance with NSF/ANSI 46, “Evaluation of Components and Devices Used in Wastewater Treatment Systems” must now be sized to filter out particles of 1.6 mm [1/16”] and have a minimum area of 550 cm²[85 in²], in addition to being installed in accordance with the manufacturers requirements.
Effluent filters:
Pumps and Siphons
Area Bed
An area bed is an infiltrative zone similar to that of a filter bed. Area beds have very small footprints, are only allowed in conjunction with alternative septic treatment units providing tertiary level septic treatment.
Area bed generally consists of a clean stone layer 250 mm thick underlain by a sand layer 200 to 300 mm thick. The sand layer may vary in depth and size depending on the septic treatment unit being used. Some advanced septic treatment systems have open bottoms that sit right on top of the stone layer while others have distribution network of PVC laterals placed in the stone layer for effluent distribution. Typically, effluent from the advanced septic treatment system will flow by gravity to an area bed. However, some septic systems have a pump as an integral part of the septic system, and sometimes a pump is added to overcome an elevation difference between the advanced septic treatment system and the area bed. The header and distribution pipes within area beds must be designed and built in such a way that they can be detected by one of the following:
Landscape design should not interfere with the natural functioning of a septic system. A balanced combination of oxygen and organisms will maintain healthy soils necessary for the septic system.
Shallow Buried Septic Trench
A shallow buried septic trench is an alternative to a conventional leaching bed. Shallow buried septic trenches may only be used when the wastewater has been treated to tertiary standards. A shallow buried septic trench consists of small-diameter PVC laterals running through open-bottom plastic chambers. The laterals are perforated at regular intervals on the top of the pipe. Effluent from the advanced septic treatment system is pumped under pressure through distribution pipes at regular intervals (time-dosed). When the dosing pump is activated, wastewater is forced along the entire length of the lateral and sprayed upwards where it hits the chamber and trickles down into the soil. By sizing the pump correctly, the entire footprint of the septic system is dosed at the same time, ensuring much more efficient distribution and use of the soil absorption system. This pressurized distribution allows for small doses to be evenly distributed along the entire length of the septic trench and greatly enhances the soil’s ability to receive and treat the effluent.
Shallow buried septic trenches are typically installed in the natural soil close to the surface of the ground, allowing plant roots and bacteria in the soil to take up additional nutrients. Shallow buried septic trenches can be installed as one row or several rows to meet minimum septic trench length standards as required by the Ontario Building Code. This method is versatile because the septic trench can follow an irregular pattern (e.g., around trees). The footprint of a shallow buried septic trench system is much smaller than a conventional septic system, because the soil is not relied upon to complete very much treatment. In addition, shallow buried septic trenches may be installed in native soils with a T-time up to 125 min/cm. Shallow buried septic trench system is appropriate for sites with a high water table, shallow depth to bedrock or tight soils.
Ontario Building Code Requirements for Shallow Buried Septic Trench Construction
Reduce the use of phosphate-based detergents, soaps and cleaners since phosphorus in detergents, soaps and cleaners doesn’t break down in a septic system. When the phosphorus leaches into nearby bodies of water, it can promote algae growth and can impair water quality and fish habitat.
CAN/BNQ 3680-600 Canadian national standard is based on the methodology of standard NSF 40 for onsite residential septic treatment technologies. Similar to standard NSF 40, the CAN/BNQ 3680-600 standard includes a six-month period with limitations and frequent sampling; this period is followed by an additional six months of less frequent sampling to verify the reliability of the septictreatment system during the four seasons of the Québec climate.
Effective January 01, 2017. CAN/BNQ 3680-600 replaced the criteria for septic treatment units set out in the 2012 Ontario Building Code, and the list of septic treatment units found in Supplementary Standard SB-5 which are deemed to meet these Ontario Building Code requirements. To be certified under CAN/BNQ 3680-600 and maintain a valid certification, all septic treatment units shall, in addition of the certification Standard, comply with the Protocol (Policies) BNQ 3680-900 defining all the terms and conditions required to maintain a product’s certification. Once a year, the BNQ will refer to the manufacturer’s database to select randomly a number of 10 sites to be inspected and sampled. The entire process is managed by the BNQ.
During the visit, the independent assessor shall first ensure that the septic system is functioning correctly and is receiving design flows and loads. 24h composite sampling will be performed by a local accredited laboratory. The septic system manufacturer should be free to choose a representative of their choice to accompany the laboratory technician and the independent assessor. If the septic system is not functioning correctly and the device or component responsible for the malfunction is not manufactured by the septic system manufacturer, the assessor shall advise in writing only the owner of the malfunction. In all other cases, the assessor shall advise in writing both the owner and the manufacturer
Effluent from 80% of the sites inspected shall comply with the performance standard applicable for the said septic system. If not, a resampling is performed for the non-complying results. If the 80% of compliance is still not reached, another series of samples from septic systems that obtained substandard results shall be drawn. If the results of these new analyses confirm initial results obtained and more than 20% of the septic systems remain substandard, another set of new site inspection/sample equal to twice as many sites as initially will have to be carried out. In this case, it is mandatory that 80% of the sites be compliant. All costs are entirely at the septic system manufacturer’s expense. Manufacturer of the septic system shall be kept informed of all results coming out of this process and, when applicable, informed in writing of any non-conformities and corrective measures required to assure the compliance of the septic systems under investigation. Manufacturer of the septic system shall introduce appropriate changes and advise certification and regulatory entities in writing. Some cases of nonconformity may require an additional audit visit and testing.
In cases where the non-conformity is caused by occupant overloading or abusing the septic system and that the owner does not agree to a modification to the septic design, the manufacturer of the septic system shall notify the regulatory agency that shall be responsible to require compliance. Tests are conducted according to the procedures specified in the Certification Requirements for CAN/BNQ 3680-600 and compliance to the requirements (80%) is part of the conditions for certificate renewal every 2 years. Failure to successfully pass the field performance audit process could lead to certification revocation and consequently automatic de-listing of the septic system from BNQ official public listing.
A small house with a maximum daily septic sewage flow rate of about 1,000 liters / day, and if that septic system is being installed in sandy soil (which has a high absorption rate) then the septic system could be quite small and be installed at a cost of a few thousand dollars. On the other hand, a big house with a maximum daily sewage flow rate of 9,000 Liters / day and hard clay soil (which can only absorb 4 liters, per square meter, per day) then the cost could be over $50,000 because a tertiary septic system may need to be installed.
The Ontario Building Code - Septic Tanks
8.2.2.3. Septic Tanks
(1) The minimum working capacity of a septic tank shall be the greater of 3 600 L and,
(2) Every septic tank shall be constructed in such a manner that any sanitary sewage flowing through the septic tank will pass through at least 2 compartments.
(3) The working capacity of the compartments required in Sentence (2) shall be sized such that,
(4) Where multiple septic tanks are to be used to meet the requirements of Sentences (2) and (3), the septic tanks shall be connected in series such that,
(5) Partitions separating the septic tank into compartments shall extend at least 150 mm above the liquid level at the outlet, and there shall be one or more openings through or above the partition.
(6) The openings required between compartments referred to in Sentence (2) shall have a total cross-sectional area of at least three times the area of the inlet pipe and be located between the top and a level 150 mm above the liquid level at the outlet to provide for the free flow of air between compartments.
(7) sanitary sewage shall pass from one compartment to another of the septic tank as follows:
(8) A septic tank shall be of such design and construction as will permit the collection and holding of sanitary sewage in it to a depth of not less than 1 000 mm, except that a depth of not less than 900 mm is permitted where the excavation is in rock, or to avoid rupture or displacement of the septic tank due to ground water pressure.
(9) Except as provided in Sentences (10) and (11), every septic tank shall be installed in such a manner that the access openings are located not more than 300 mm below the ground surface.
(10) Where the top of the septic tank is located more than 300 mm below the ground surface, it shall be equipped with risers that extend from the access opening of the septic tank to within 300 mm of the ground surface.
(11) Where risers are used they shall conform to the requirements of CSA B66, "design, Material, and Manufacturing Requirements for Prefabricated Septic Tanks and Sewage Holding Tanks", and shall have adequate access openings to allow for regular maintenance of the septic tank.
Our fee to prepare a typical residential septic design with stamped engineering drawings and plans to obtain septic permit is $1,295+HST.
The septic contractor may have to contact Municipality / Health Department Officials to determine their requirements and if they need inspectors on site for the test pit investigation / assessment and number of test pits and arrange for septic test pit digging equipment based on site accessibility.
Our service area includes all the regions. Counties in Ontario including Toronto (City of Toronto), Hamilton (City of Hamilton), Region of Durham which includes Oshawa (City of Oshawa), Pickering (City of Pickering), Clarington (Municipality of Clarington), Ajax (Town of Ajax), Whitby (Town of Whitby), Brock (Township of Brock), Scugog (Township of Scugog), and Uxbridge (Township of Uxbridge), Region of Halton which includes Burlington (City of Burlington), Halton Hills (Town of Halton Hills), Milton (Town of Milton), and Oakville (Town of Oakville), Region of Peel which includes Brampton (City of Brampton), Mississauga (City of Mississauga), Caledon (Town of Caledon), Region of York which includes Vaughan (City of Vaughan), Aurora (Town of Aurora), East Gwillimbury (Town of East Gwillimbury), Georgina (Town of Georgina), Markham (City of Markham), Newmarket (Town of Newmarket), Richmond Hill (City of Richmond Hill), Whitchurch - Stouffville (Town of Whitchurch-Stouffville), Bradford-West Gwillimbury (Town of Bradford West Gwillimbury) and King (Township of King), Kawartha Lakes (City of Kawartha Lakes)
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Land & Building Experts
PEO COA # 100205934
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