Self-Test 1

1. c. Holding tanks and privies
2. a. A plumber
3. c. Private Inspector
4. d. Recreational
5. b. The septic tank
6. a. The field piping
7. b. BOD5
8. d. Houses discharging > 22700 litres/day
9. b. Dispersal area
10. a. A soil analysis

Self-Test 2

1. a. Type 1
2. b. CAN/CSA B66-00
3. c. Septics
4. d. A filter
5. a. Dosing
6. b. Type 2
7. d. Trickling or gravity distribution
8. a. Speed levelers
9. b. Access risers
10. c. 18-36 inches
11. b. Aerobic
12. c. Trickling
13. a. A float switch
14. a. Pressure distribution
15. c. Gravelless Infiltrator®
16. b. Seepage bed
17. d. Transpiration
18. b. Alberta At Grade
19. d. BC Zero Discharge Lagoon
20. c. CTDS

Self-Test 3

1. c. Primary treatment
2. d. Secondary
3. b. De-chlorination
4. a. Sludge treatment
5. b. A sanitary landfill

Self-Test 4

1. d. Gather information from the owner
2. b. Daily design flow
3. d. 1645 litres/day
4. a. 50%
5. c. 937.5 litres/day
6. a. 2, 1, 3, 4
7. b. Hydraulic loading rate
8. c. Restrictive layer
9. d. Vertical separation
10. a. Soil horizon
11. b. Blinding layer
12. b. The clay will block flow through it
13. a. Flow through it will be too fast
14. c. Use an above grade system or a lagoon
15. a. Minutes per inch
16. a. Table II-5
17. c. Table II-7
18. a. AIS divided by trench width
19. d. Lightweight, non-woven geotextile over the gravel
20. b. 1.8 m
21. b. More than 15 cm
22. b. 15 cm
23. d. A toilet flange
24. c. 90 cm
25. c. 4” or 6”

Self-Test 5

1. b. Shorter distance between inlet and outlet pipes
2. c. Quiescent
3. d. 3 times the DDF
4. b. 75% to 50% of the total working volume
5. d. 5 years
6. a. Lower cost of pumpouts over time
7. b. [latex]\tfrac{1}{8}[/latex]”/ft ([latex]\tfrac{1}{100}[/latex])
8. d. Through the building sewer
9. b. Risers
10. b. 15 cm
11. b. 50 cm
12. c. 100 feet (30 m)
13. b. 10 feet (3 m)
14. c. 100 feet (30 m)
15. d. 3 metres (10 feet)

Competency D2

Self-Test 1

1. b. 61 cm (24 inches)
2. a. ½ inch of mercury
3. b. 67%
4. d. 150 cm (60 inches)
5. d. Flow
6. d. 8 years
7. a. Biomat
8. c. It slows the flow and gives more time for filtration
9. c. Flush bleach periodically
10. d. Frequent dosing pump failure
11. d. The formation of hydrochloric acid
12. a. Polyethylene
13. c. Plastic tanks don’t have removeable lids
14. c. Their cost and size are relatively small
15. b. Shocking the system

Let Us Know if You are Having Problems Accessing This Book

• The name of the resource
• The location of the problem by providing a web address or page description.
• A description of the problem
• The computer, software, browser, and any assistive technology you are using that can help us diagnose and solve your issue (e.g., Windows 10, Google Chrome (Version 65.0.3325.181), NVDA screen reader)

• Web form: BCcampus Open Ed Help
• Web form: Report an Error

What is a Private Sewage Disposal System?

• restrictive soil conditions and percolation rates
• insufficient field area
• proximity to property boundaries, water tables and wells

• one or more treatment method(s)
• a discharge area

Who Can Install Septic Systems?

• an ROWP is certified by the ASSTBC, usually by taking requisite courses of training delivered by accredited trainers
• a professional typically means an engineer accredited by APEGBC (Association of Professional Engineers and Geoscientists of BC)

• Planner, responsible for site and soil evaluation and planning of systems
• Installer, responsible for installation of systems
• Maintenance Provider, responsible for maintenance of systems

• Private Inspector (PI), responsible for the assessment of existing systems, typically to support real estate transactions or building permit applications.

• Private Inspector Residential (PIR), and
• Private Inspector Commercial (PIC)

Purpose of the SSR

Bacteria at Work

Anaerobic Bacteria

Aerobic Bacteria

Treatment Methods

• Type 1: Treatment by a septic tank and dispersal field only.
• Type 2: Treatment that produces an effluent consistently containing less than 45 mg/L of TSS and having a BOD₅ of less than 45 mg/L.
• Type 3: Treatment that produces an effluent consistently containing less than 10 mg/L of TSS and having:
  • A BOD₅ of less than 10 mg/L.
  • A median fecal coliform density of less than 400 Colony Forming Units per 100 mL.

• Systems that process sewage flow of less than 22700 litres (4989 imperial gallons) per day
• Single-family dwellings or duplexes
• A combination of sewage systems that addresses different buildings on a single parcel of land
• Structures that serve one or more parcels on strata lots or on a shared interest of land.

• Gravity distribution systems
• Pressure distribution systems, and
• BC zero discharge lagoons, evapotranspiration (ET) beds and evapotranspiration absorption (ETA) beds (all are limited to application in certain parts of the province)

Dispersal Area

• Gravity distribution, either:
  • Trickle gravity, or
  • Dosed gravity
• Uniform distribution, meaning either:
  • Pressure distribution
  • Subsurface Drip Dispersal (SDD), or
  • Alternate methods of uniform distribution, provided that they meet the standards set out in the SPM

Self-Test 1

Type 1 Septic Systems

The Septic Tank

• Solids, including seeds, peels and other hard-to-digest particles that settle to the tank bottom to form a layer known as “sludge.” Sludge is meant to accumulate and be stored in the tank until pumped out.
• Fats, soaps and oils float on the surface of the liquid to form a layer known as “scum.” Scum forms an insulating barrier above the effluent and, like the sludge, is meant to not leave the tank until being pumped out.
• The wastewater (“effluent”) layer between the scum and sludge leaves the tank through gravity piping or pumping and is directed into the dispersal system.

Package Sewage Treatment Plants

The Distribution Box

The Dispersal Dystem

Trench Systems

Gravity Distribution: Trickling Systems

Gravity Distribution: Dosed Systems

• The entire field gets a workout, rather than just the first few metres of it
• The field is allowed to “breathe” (rest) between doses, promoting aerobic bacterial action
• Freeze up of the field is less likely to occur in cold climates

Pressure Distribution

• Pressure distribution, and
• Subsurface drip dispersal

Subsurface Drip Dispersal (SDD) Systems

Alternate Dispersal Methods

• Gravelless “Infiltrator®” systems
• At Grade and raised systems
• Seepage bed systems
• Sand mounds and sand-lined trenches
• Evapotranspiration (ET) and evapotranspiration absorption (ETA) beds
• Lagoons
• Combined treatment and dispersal (CTDS)

Gravelless “Infiltrator®” System

At Grade Beds and Raised Systems

Seepage Bed Systems

Sand Mounds and Sand-Lined Trenches and Beds

ET and ETA Beds

• bed vegetation cover not well maintained to maximise evapotranspiration
• inadequate exposure to wind, or shading by trees, lowering the rate of evapotranspiration
• uneven distribution of effluent caused by gravity feeding instead of by a pump or pressure dosing
• beds too small for amount of effluent (hydraulic load).

BC Zero Discharge Lagoons

Combined Treatment and Dispersal Systems

Self-Test 2

Media Attributions

• Figure 1. "Conventional Type 1 system" from United States Environmental Protection Agency is used for non-commercial, scientific and educational purposes.
• Figure 2. "Single compartment tank" from Coosa Riverkeeper is used for educational purposes under the basis of fair dealing.
• Figure 3. "Two-compartment tank" from Lake Leelanau Lake Association is used for educational purposes under the basis of fair dealing.
• Figure 4. "Septic tank with siphon chamber" from Integrated Publishing is used for educational purposes under the basis of fair dealing.
• Figure 5. "Siphon" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 6. "Dosing tank using pump" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 7. "Aerobic treatment unit" from United States Environmental Protection Agency is used for non-commercial, scientific and educational purposes.
• Figure 8. "Distribution box (elevation view)" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 9. "Plastic D-box" from Polylok is used for educational purposes under the basis of fair dealing.
• Figure 10. "Typical trench with components and dimensions" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 11. "Trickling disposal field" from EEPCO is used for educational purposes under the basis of fair dealing.
• Figure 12. "Siphon" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 13. "Dosing tank using pump" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 14. "Pump vault" from Infiltrator Water Technologies is used for educational purposes under the basis of fair dealing.
• Figure 15. "Pressure distribution system" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 16. "Subsurface drip dispersal system (SDD)" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 17. "Infiltrator® chamber" from Infiltrator Water Technologies is used for educational purposes under the basis of fair dealing.
• Figure 18. "At Grade bed" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 19. "Alberta At Grade bed" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 20. "Seepage bed" from Sentinel Excavating is used for educational purposes under the basis of fair dealing.
• Figure 21. "Sand mound" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 22. "ET bed" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 23. "BC zero discharge lagoon" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 24. "Combined treatment and dispersal system Onsite Sewage Inspection Industry Background" is used for educational purposes under the basis of fair dealing.

Image descriptions

• the scale at which the process occurs
• the size and complexity of the components
• the level of treatment achieved
• the chemistry and quality control used
• the end destination of the treated effluent

• Primary treatment
• Secondary treatment
• Tertiary treatment
• Sludge treatment

Primary Wastewater Treatment

Secondary Wastewater Treatment

Tertiary Treatment

Sludge Treatment

Self-Test 3

Media Attributions

• Figure 25. "Municipal wastewater treatment flowchart" by Camosun College is licensed under a CC BY-NC-SA licence.

Planning the Installation

• The full legal name of the owner(s), and contact information
• Legal description, civic address, and tax assessment roll number for the subject property
• Current or planned water source (i.e., an approved community water system, an on-site water well or freshwater body such as lake or creek)
• Current and planned uses of the property (i.e., residential only, commercial uses including home based business, or mixed commercial/residential)
• Current or planned size and use of non-residential buildings
• Current or planned water source (i.e., an approved community water system, an on-site water well or freshwater body such as lake or creek)
• Information regarding any wells located on the property, including well logs
• Current or planned residence information including:
  • Living and non-living areas of the residence
  • Number of bedrooms
  • Anticipated number of occupants
  • Water treatment devices (i.e., water softeners, filtration systems, disinfection, or similar devices)
  • Garbage grinders/in-sink garbage disposal units
  • Any other anticipated usage patterns that may affect sewage volume or constituents, which may include:
    • Frequent large numbers of guests (i.e., from social events)
    • Non-typical food processing such as canning, high volume of baking or deep frying, beer or wine making
    • Home-based businesses with associated sewage discharges
    • Hobbies with associated sewage discharges (e.g. photography, painting, pottery
• Information for the owner on their responsibilities under the SSR
• A signed declaration statement by the owner(s) including the following:
  • Identification of ownership (who are the legal owners?)
  • Confirm the accuracy of information provided
  • Understanding that system use (including the design flow) is to be per the filing submitted to the Health Authority

Determine the Daily Design Flow (DDF)

[latex]1\;300\text{ L}+(15\times3=45\text{ L})=1\;345\text{ L}[/latex]

[latex]1\;345\times1.5=2\;017.5\text{ L}[/latex]

[latex]350\times3.75=1\;312.5\text{ L}[/latex]

[latex]1\;312.5\times1.5=1\;968.75\text{ L}[/latex]

• Larger overall floor area with larger rooms than an average home
• More water use appliances than an average home
• Large parties, frequent guest use, and the probability of domestic service workers adding to the DDF

Determine Site Conditions for Dispersal

• site capability standards, as found in Section II- 4.1.2
• vertical separation standards from Section II- 5.3, as well as
• the standards of Section II- 6 for the specific type of dispersal system

Determining Soil Characteristics

• Excavate a minimum of two test pits (observation holes). In some cases, two pits will not be enough to describe the soil conditions. If platy structure is found, site investigation should include a minimum of 4 observation test pits in the dispersal area and two in the receiving area to determine the extent and uniformity of the platy soil layer(s) more accurately. If soils are variable or the area is large, excavate additional test pits
• Augered (bored) holes can be used to investigate soil conditions. This may be preferred on some sites to minimize the number of test pits. A minimum of two observation test pits should be excavated to confirm the auger test results
• The test pit should be dug to a depth that provides the soil and water table information for designing the sewage system. In all cases test pit depth may be limited by refusal, i.e., rock or other layer which cannot readily be excavated. If feasible, considering the hardness of the ground, excavate to:
  • A minimum of 1.2 m depth in total
  • A minimum of 0.9 m below the proposed infiltrative surface
  • A minimum of 1.5 m below the proposed infiltrative surface, if Volume II standards specify a larger vertical separation. This would apply, for example, in the case of gravity dispersal to gravelly sand soil (the standards specify a vertical separation of 150 cm)
  • A minimum of 3 m overall depth and a minimum of 1.2 m below the planned base elevation, for a proposed BC zero discharge lagoon. If sand lenses or rock outcrops are suspected, consider investigation to greater depth
  • A minimum of 1.2 m below the base of a proposed ETA bed.

• The more clay there is in soil, the less favourable it is for a trickling gravity system because of clay’s low hydraulic conductivity.
• As well, the coarser and grainier the soil, such as gravel or sand, the less favourable it is because the effluent flows quickly through it and will not be retained long enough for proper aerobic bacterial action to take place.
• Soils that have a mixture of sand, loam and a limited amount of clay can usually be suitable for a disposal field. Again, the amounts of each constituent will influence the percolation rate through the soil and affect the hydraulic loading rate.

Percolation Test Procedure

1. Perc test holes should be made at points and elevations selected as typical in the proposed absorption field.
2. Typically, test holes are to be dug at each end of the area of the absorption field and near the centerline. Further holes could be needed, depending upon the nature of the soil, the results of the first tests and the size of the proposed dispersal area. Testing of the receiving area may also be necessary.
3. Test holes should be 30 cm (12″) square or 36 cm (14″) round and excavated to the proposed depth of the absorption field (or as instructed by the designer). It is generally easiest to dig a larger hole part way down, then dig an 18 to 20 cm (7 to 8″) deep accurately sized test hole in the base of the larger hole.
4. To make the percolation test more accurate, any smeared soil should be removed from the walls of the test holes. This is best achieved by digging the hole approximately 5 cm undersized (2″) and then enlarging the hole to the accurate size as follows: using a rigid knife, insert the blade into the top side of the hole opposite you approximately 2.5 cm (1″) deep, holding the blade with its cutting edge vertical. Pull the blade away to break out a chunk of soil, repeat about 2.5 cm (1″) apart around the hole, then repeat for another “ring” below until reaching the base. The result will be a hole with a ragged inner surface which looks like a freshly broken clod of soil.
5. The base of the hole should be cleaned of debris and be approximately flat. Use a metal scoop or similar implement. It should also be picked to present a natural surface. Note that a picking action, using a pointed tool, is needed, not a scratching action (which just produces smears that are indented).
6. Place 5 cm (2″) of clean fine gravel in the bottom of the hole. If the sidewalls are likely to collapse, use a paper basket to support the sidewalls (see note below). Place a piece of white plastic or similar provided with clear marks at 5″ and 6″ from the bottom of the test hole prior to adding the gravel. For greater accuracy a float and pointer arrangement can be set up.
7. If the soil contains considerable amounts of silt or clay, and certainly for any soil with “clay” as part of the texture description, the test holes should be pre-soaked before proceeding with the test. Pre-soaking is accomplished by keeping the hole filled with water for 4 hours or more. The water should be added carefully and slowly to avoid disturbing the soil (including the sidewall soils). The test should be carried out immediately after pre-soaking.
8. To undertake the test, fill the accurately sized test hole with water. The water should be added carefully and slowly to avoid disturbing the soil (including the sidewall soils). When the water level is 5″ or less from the bottom of the hole, refill the hole to the top. No recording of time needs be done for these 2 fillings.
9. When the water level after the second filling in step 8 is 5″ or less from the bottom of the hole, add enough water to bring the depth of water to 6″ or slightly more. Note that these measurements are from the base of the soil bottom (using the marker installed in step 6), not the gravel layer.
10. Observe the water level until it drops to the 6″ depth, at precisely 6″, commence timing. When the water level reaches the 5″ depth, stop timing, record the time in minutes.
11. Repeat steps 9 and 10 until the last two rates of fall do not vary more than 2 minutes per inch or by more than 10% (whichever is less).
12. Report the slowest rate for each hole.
13. Backfill the holes with the excavated soil and flag and label their locations so you can recognize them when creating the plan of the installation.

Determine the Hydraulic Loading Rate (HLR), Area of Infiltrative Surface (AIS), and Linear Loading Rate (LLR)

[latex]\text{DDF (L/day)}\div\text{HLR (L/day/m}^2)=\small\text{minimum area of infiltrative surface (AIS) needed (m}^2)[/latex]

• A 3-bedroom house, with no garburator and not > 280 m² of living area applied to Table II-8 = 1300 litres/day DDF
• After a soil test, it has been determined that the soil structure and consistence from Table II-21 (shown below) is considered “favourable” for a gravity trickle dispersal system

• The percolation rate, from the percolation test, is found to be 3 minutes/inch
• The soil type, from the soil analysis, is determined to be “loamy sand”

[latex]\small\text{minimum area of infiltrative surface (AIS) needed (m}^2)= \normalsize\text{DDF (L/day)}\div\text{HLR (L/day/m}^2)[/latex]

[latex]1\thinspace300\text{ litres/day}\div30\text{ litres/day/m}^2=43.33\text{ m}^2\text{ of infiltrative surface}[/latex]

Determine the Linear Loading Rate (LLR)

[latex]\text{DDF (L/day)}\div\text{LLR (L/day/m)}=\text{minimum system contour length (m)}[/latex]

[latex]1\thinspace300\text{ litres/day}\div35\text{ litres/day/metre}=37.1\text{ metres of contour length}[/latex]

Example of Trench Length Needed

[latex]\text{minimum AIS needed}=\text{DDF}\div\text{HLR}=1\thinspace300\div30=43.33\text{ m}^2[/latex]

[latex]43.3\text{ m}^2\div0.6\text{ m}=72.2\text{ m }(236\text{ ft})[/latex]

• Trench widths are 30-90 cm (12-36 in.); on slopes greater than 15%, use/specify a trench width of 30-60 cm (12-24 in.)
• Limit laterals to 15 m (50 ft) or less
• Install trenches level, or sloping in the direction of flow at no greater than 5 cm in 30 m (0.2%)
• Space trenches a minimum 1.8 m (6 ft) from centre line to centre line (c-c)
• On slopes greater than 15%, space trenches at least 3 m (10 ft) c-c
• Provide at least 0.9 m (3 ft) between adjacent trench edges
• Do not compact the soil under or over the lateral
• Use aggregate (drain rock) in the size range of 12 mm-63 mm (½″-2 ½″)
• Install aggregate to at least 15 cm (6 in.) depth below the distribution pipe and at least 5 cm (2 in.) above the pipe
• Install cover soil to at least 15 cm (6 in.) depth
• Install at least two infiltrative surface observation ports per drainfield
• Place observation ports 10–15 cm from the distribution pipe, and near the midpoint of the lateral
• Use 100 mm (4″) or larger diameter pipe

Self-Test 4

Treatment Methods

• Type 1: Treatment by a septic tank and dispersal field only.
• Type 2: Treatment that produces an effluent consistently containing less than 45 mg/L of TSS and having a BOD₅ of less than 45 mg/L.
• Type 3: Treatment that produces an effluent consistently containing less than 10 mg/L of TSS and having:
  • A BOD₅ of less than 10 mg/L.
  • A median fecal coliform density of less than 400 Colony Forming Units per 100 mL.

Septic Tank Installation

• Larger surface area (higher surface area-to-volume ratio)
• Longer distance between inlet and outlet pipes (higher length-to-width ratio)
• For two compartment tanks, letterbox openings in the compartment divider

• For a daily design flow of up to 9100 L/day, the tank should have a working volume of at least 3 times the DDF
• For a DDF of more than 9100 L/day, the working volume should be at least 15000 L + (DDF in litres × 1.34) or as otherwise determined by a design professional

• To improve oil and grease removal
• To improve suspended solids removal
• To increase interval between pump outs
• To improve flow equalization where large surge flows are expected, such as from sewage sump pumps in basements.

Tank Placement

Flotation Prevention

Tank Venting

Tank Access

• Any components that need to be accessed or removed should have handles or disconnect fittings located within 15 cm of the riser or access lid.
• Access lids should be exposed and readily accessible. They should be flush with finished grade or above (2.5 cm above is preferred).
• Access lids should be secure, either requiring special tools for removal, or provided with a lock.
• Removable access lids (including any job-built access components) should be capable of supporting at least 150 kg without collapse.
• Risers should be at least 50 cm internal diameter, or 60 cm when over a divider or if needed to access a pump etc.
• For tanks that are installed deeper than normal (over 90 cm of fill over the tank lid), larger access risers with a minimum diameter of 76 cm are preferable.
• Pump chambers will also require access. Provide two risers if one will be largely filled with the pump, connections, and float switches.
• The inlet pipe to the pump chamber should be accessible for visual inspection by the maintenance provider, or for collecting effluent samples for laboratory testing.
• Extend access risers to finished grade and slope the ground away from the riser lid
• Insulate the riser in cold climates

Backfilling

Tank Testing

Distribution Box Installation

Horizontal Separation

Commissioning the System

• Set float switches or transducers, and test the system operation, including alarms
• Set the pump control panel (timers, data loggers and programmable controls) and test operation
• Test pumps, fan, and blower operation, and measure the voltage and run amperage
• Check the force mains, including the pressure effluent collection mains, for leaks
• Flush all lines in the treatment and pumping systems, transport lines and dispersal system
• Test back-flow preventers (i.e., check valves).
• Test and adjust the D-box and outlet controls (gravity system with D-box).
• Test the pressure distribution residual pressures (a.k.a. “squirt test”). This may include the final pressure distribution system, and treatment system distribution piping (i.e., sand and textile media filters). Adjust valves, as required, to equalize pressure. Record distal pressures (squirt heights).
• Test and record pump discharge flow rate or draw down. Record pump run amperage.
• Record the initial control panel settings, system operating parameters, and the start-up data logs. Note any changes to the design or operational settings.
• Complete a general review of the system operation to verify that it is operating as intended, and in accordance with the manufacturer’s specifications
• Perform baseline monitoring if applicable (e.g., record water table levels in observation standpipes, collect and test samples of water from drainage system).
• Put the sewerage system into service. Ensure that the breakers, switches and valves are in operating position, the tank lids are secure and that the site has been left in a safe and tidy condition.

Self-Test 5

Media Attributions

• Figure 26. "Typical gravity distribution trench" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 27. "Typical trench installation with observation port" by Camosun College is licensed under a CC BY-NC-SA licence.
• Figure 28. "2-compartment septic tank" by Camosun College is licensed under a CC BY-NC-SA licence.

Image descriptions

Testing the Septic Tank

Water Test

• Water is its densest at about 4°C (just above freezing), so water put into a tank at 10 to 20°C (typical of groundwater) and left in the tank overnight at freezing temperatures will drop the level in the tank a substantial amount (about 0.2% or 11 litres in a 5600 L tank). A "loss" of 11 litres (0.2%) in the risers will look like a leak.

Vacuum Test

Testing the Dispersal System

• A filtered (screened) vault with the inlet at the centre of the clear zone
• A maximum pumping rate of 190 L/min (50 USGPM).
• A maximum drawdown of 10% of the tank working volume.
• An alarm reserve volume of at least 50% of the daily design flow (DDF), measured to the tank lid base (without backup into building).

Maintenance Plan

• An operation manual for the system
• A schedule for maintenance and monitoring including prescribed maintenance tasks
• A statement of the allowable average flow for any 30-day period
• Contact information and emergency contact information for the AP who filed the system, the installer, a maintenance provider and the electrician
• Information and advice for the system owner, and
• Sign off by owner that they have received and understood the requirements of the plan

Pump Outs

• Total solids accumulations are more than ⅓ of the internal height of the tank
• The scum layer reaches the top of outlet T in a one compartment tank
• The scum layer reaches the top of inlet T in a two-compartment tank
• Any obvious carry-over of solids to the second compartment
• Premature effluent filter clogging
• An increase in TSS or FOG (fats, oils and grease) noted in downstream components

Vegetation and Dispersal Systems

• Reducing effective rainfall (the amount of rain that actually soaks into the soil)
• Maintaining soil structure and organic matter content in the long term
• Reducing temperature extremes, and particularly reducing risk of freezing

Biomat: Good, Bad, or Both?

Soil clogging layer at and below the infiltrative surface to soil or to sand or other media. The layer of biological growth, organic compounds (including polysaccharides and polyuronides produced by bacteria in the mat) and inorganic residue that develops at the wastewater soil interface and extends up to about 25 mm into the soil matrix. The term is used loosely to include all soil “clogging” affects, including pore size reduction, alteration of soil structure and gas production by the micro-organisms. Also referred to as Biocrust, Clogging Mat, and Clogging Zone.

A black, jelly-like permeable layer forms in the soil just below or around the drain field trenches where the septic effluent is discharged. This layer is what is referred to as biomat, clogging mat, biocrust, or clogging zone, and it plays an important role in the processing of pathogens and biological solids. Without biomat, the septic system would be releasing partially treated effluent into the soil thereby resulting in pollution of groundwater and any nearby wells, ponds, and streams. As the wastewater from the septic tank is fed into the soil absorption system for further treatment, bacteria grow under the distribution lines where they meet the soil or gravel. This biological mat forms on the sides and bottom parts of a leach field trench, helping to reduce the infiltration rate of water into the soil and thereby giving bacteria more time to treat the water before it is released, which translates to a “good thing.” Biomat is made up of live and dead anaerobic bacteria and their by-products which attach themselves to the soil particles. These microorganisms usually rely on the organic matter in the effluent for sustenance and therefore biomat is often referred to as the actual site for treatment of effluent. In a new system, biomat will start forming at the trench bottom where the effluent discharges from and then it will slowly grow along the trench walls. Because biomat is not as permeable as soil, effluent will trickle along the trench looking for a place with little or no biomat and this helps to slow down the infiltration of wastewater. Biomat slows down the flow rate of wastewater thereby giving it time to filter out viruses and other pathogens.

How to Prolong the Biomat Lifetime (Extend the Life of the Dispersal System)

• Proper maintenance. Taking good care of a septic system will help to avoid many issues including ponding in the leach field area due to the overgrowth of biomat. The AP Maintainer designated for the system will ensure that routine maintenance in the official Maintenance Plan is performed.
• Avoid hydraulic overload. Hydraulic overloading is one of the main causes of the overgrowing of biomat. Through the force of gravity, effluent is distributed somewhat evenly across the drain field area from where it slowly sips through the trenches and back into the groundwater. As has already been established, biomat slows down this process which is a good thing. In an ideal scenario, this process continues day in day out. However, when too much water is sent into the disposal field at one time, the field will become waterlogged. When the field gets too wet, the rate of breaking down organic matter reduces greatly and the waste products that are produced by the bacteria get more time to settle. This ultimately leads to unprecedented growth of biomat. To avoid this, it is a good idea to avoid sending too much water to the septic tank all at once. If there are lots of people living in a household, space out showers instead of taking all of them in a row. Also, spread out laundry across the week instead of doing a huge load of laundry in a single day.
• Septic tank filter system. Septic tanks filters help trap suspended solids from going into the drain field. Because the bacteria rely on organic waste for sustenance, giving them too much food around the clock will increase their numbers exponentially and will, in turn, increase their waste which will increase the rate at which the biomat grows. Proper maintenance of filters avoids this.
• Don’t flush harmful products. When harmful products are flushed, they can deplete the number of bacteria in the septic tank as well as in the dispersal system. This will mean that organic waste will not be properly digested in the tank and much of it will end up in the field. When too much of the suspended solids flow into the field, they contribute to the excessive growth of biomat. To avoid this, do not flush anything apart from human waste and tissue paper. Installing washing machine filters can also help to prevent fibres from clogging the effluent filter in the tank. Additionally, avoid any substance that might harm bacteria. These include:
  • bleach and disinfectants
  • antibacterial soaps
  • antifreeze
  • chlorinated backwash from hot tubs, swimming pools, R/O units, water treatment filters, etc.

Conclusion

Additives

Media Attributions

• Figure 1. "Pumper truck" by Mitchell Schultheis is under a CC BY-SA 3.0 licence.

Slow or Stopped Drainage

“Ponding” over the Dispersal Field

Contaminated Drinking or Surface Water

Overall Troubleshooting

Damaged Concrete Septic Tanks

• Poor installation techniques: improper bedding and compaction can cause the tank to settle unevenly and develop cracks
• Manufacturing defects: These can sometimes occur and may not be visible upon pre-installation inspection
• Mechanical damage: rough handling when being installed or heavy traffic over the installed tank can cause it to crack or collapse
• Corrosion: the anaerobic process inside the tank emits hydrogen sulfide gas, and when this mixes with oxygen from the air, hydrochloric acid is produced. This forms at and above the waterline and causes the concrete to spall or flake off over a prolonged period. This continues until the tank wall is so badly compromised that repair or replacement is required.

Concrete Tank Repair

Damaged Plastic and Fiberglass Septic Tanks

• A manufacturing flaw
• An event in handling, such as a puncture from a forklift
• An installation event, such as improper backfill, uneven compaction under it, or being dropped from a crane

Polyethylene Tank Repair

Fibreglass Tank Repair

Damages to a Distribution Box

Damages to Field Piping

Self-Test 1

Tips for Using This Textbook

• Search the textbook.
  • If using the online webbook, you can use the search bar in the top right corner to search the entire book for a key word or phrase. To search a specific chapter, open that chapter and use your browser's search feature by hitting [Cntr] + [f] on your keyboard if using a Windows computer or [Command] + [f] if using a Mac computer.
  • The [Cntr] + [f] and [Command] + [f] keys will also allow you to search a PDF, HTML, and EPUB files if you are reading them on a computer.
  • If using an eBook app to read this textbook, the app should have a built-in search tool.
• Navigate the textbook.
  • This textbook has a table of contents to help you navigate through the book easier. If using the online webbook, you can find the full table of contents on the book's homepage or by selecting "Contents" from the top menu when you are in a chapter.
• Annotate the textbook.
  • If you like to highlight or write on your textbooks, you can do that by getting a print copy, using the Digital PDF in Adobe Reader, or using the highlighting tools in eReader apps.

Webbook vs. All Other Formats

Self-Test 1

Self-Test 2

Self-Test 3

Self-Test 4

Self-Test 5

Self-Test 1