Effluent Treatment and Disposal

7. Effluent Treatment and Disposal

7.1 Design Standards

1. a disposal field,
2. a treatment mound,
3. an open discharge system,
4. a lagoon, or
5. a sand filter or sand filter and disposal field.

The types of effluent disposal systems indicated must comply with the specified design criteria.

Modified designs of these systems or alternative systems may be granted approval to be installed with the submission of sufficient documentation, testing data, and any other information deemed necessary along with a request for a site specific variance to the Technical Administrator prior to the installation of the system.

1. a disposal field,
2. a treatment mound, or
3. a sand filter, or sand filter and disposal field.

Percolation Test means a test performed to determine a rate at which soil will absorb water.

See Pg. 41, Article 7A.1.4
See Pg. 94, A.6. Percolation Test Procedure in Appendix "A"

Soil Texture Classification means a classification of soil set out in Pg. 42, Article 7A.1.5. in the Standard of Practice, having a soil composition determined by Grain or Particle Size Analysis.

The percolation test or soil texture is a key measurement required for sizing a soil treatment and absorption system.

The best criteria to use in sizing a system is to use both the percolation test and soil texture while also considering the soil structure.

See Pg. 114, Soil Tests

7.1.3. Where a percolation test is used the effluent loading rates shall be calculated as set out in Article 7A.1.4.

Intent: A percolation test is used to determine the rate that the soil will accept water. The results of this test provide some system sizing criteria. Other criteria will also need consideration when sizing a system, such as soil structure, soil texture, type of clay, seasonal high water table and water quality, for example: Sodium Adsorption Ratio.

See Pg. 89, Table A.4.A. in Appendix "A" for more information on loading rates in litres per m2 or (gallons per sq. ft.) as related to the results of percolation tests.

7.1.4. When a particle or grain size analysis test is used to establish a soil texture classification determined in Table 7A.1.5.A., the effluent loading rates shall be determined by Article 7A.1.5.

Intent: A soil grain size analysis is used to determine a soil texture classification that can be related to the hydraulic conductivity of the soil or the rate that the soil will accept water. The results of this test provide some system sizing criteria. Other criteria will also need consideration when sizing a system, such as soil structure, soil texture, type of clay, seasonal high water table and water quality, for example: Sodium Adsorption Ratio.

Soil Texture Classification means a classification of soil set out in Pg. 42, Article 7A.1.5. determined by the results of a Grain or Particle Size Analysis.

Soil texture has a significant influence on the rate at which long term acceptance of effluent into the soil will occur.

Grain or Particle Size Analysis means a standard hydrometer method of establishing percentage of sand, silt or clay particles in a soil sample.

See Pg. 121, Particle or Grain Size Analysis Test in Appendix "B"

1. not faster than 5 minutes per 25 mm (1 in.) as determined by a percolation test using water or, 5 Litres per square metre per minute, and
2. not slower than 60 minutes per 25 mm (1 in.) as determined by a percolation test using water or, 0.042 Litres per square metre per minute.

Soils that allow the effluent to move through it quickly do not properly treat the effluent. Conversely soils that do not allow the effluent to easily move through it will soon plug up as it is difficult to treat the organic content in the sewage which then plugs the soil.

See Pg. 65, Article 10.2.2 in the Standard of Practice.
See Pg. 94, A.6. Percolation Test Procedure in Appendix "A"
See Pg. 114, Percolation Test in Appendix "B"
See Pg. 181, Fig. DF 1A in Appendix "B"
See Pg. 133, Location of Disposal Fields in Appendix "B"
See Pg. 147, Treatment Mounds in Appendix "B"

1. 1500 mm (5 ft.) in a disposal system supplied with effluent from a septic tank and no other treatment, or
2. 900 mm ( 3 ft.) in
   1. a disposal field supplied with effluent from a Class 1 packaged sewage treatment plant or a sand filter,
   2. a treatment mound, or
   3. an open bottom sand filter.

Intent: Depending on the level of initial or primary treatment, the effluent must travel a corresponding distance through the soil to complete treatment.

Vertical Separation means the depth of unsaturated soil between the bottom of an effluent disposal component and the highest seasonal water table.

The effluent must travel through a distance of unsaturated soil to complete treatment. Treatment does not occur in saturated soil.

Where nitrate and or phosphate pollution is a concern because of shallow unconfined aquifers, additional separation or further treatment prior to the effluent entering the soil may be required to meet the requirements of article 1.2.1

See Pg. 39, Article 7.2.1
See Pg. 45, Article 7A.2.1
See Pg. 53, Article 8.2.1.(1)
See Pg. 59, Article 9.2.1
See Pg. 59, Article 9.2.2
See Pg. 65, Article 10.2.1
See Pg. 178, Fig. Vertical Separation in Appendix "B"
See Pg. 136, Raised Disposal Fields in Appendix "B"
See Pg. 133, Location of Disposal Fields in Appendix "B"
See Pg. 147, Treatment Mounds in Appendix "B"
ee Pg. 160, Open Discharge in Appendix "B'

7.2 Installation Standards

See Pg. 38, Article 7.1.6 for vertical separation requirements
See Pg. 178, Fig. Vertical Separation in Appendix "B"

7.2.2. Where percolation tests are required, a minimum of 2 tests shall be done at the disposal site in accordance with Appendix A.6. Percolation Test Procedure.

Intent: A percolation test is a standardized test procedure to determine a rate that the soil will accept water. The results of this test procedure provide some system sizing criteria.

See Pg. 89, Table A.4.A in Appendix "A"
See Pg. 114, Percolation Test in Appendix "B"

7A. Disposal Fields - General

7A.1 Design Standards

1. Article 7A.1.4., or
2. Article 7A.1.5.

See Pg. 126, Disposal Fields - General in Appendix "B"
See Pg. 135, Split Disposal Fields in Appendix "B"

1. supplied with effluent from a Class 1 packaged sewage treatment plant may have
   1. a 30% reduction in the area of weeping lateral trench bottom required in Article 7A.1.1., or
   2. a 50% reduction in the area of weeping lateral trench bottom required in Article 7A.1.1. when pressure distribution of effluent is used in accordance with Article 7A.1.9.,
2. supplied with effluent from a sand filter may have
   1. a 30% reduction in the area of weeping lateral trench bottom required in Article 7A.1.1., or
   2. a 50% reduction in the area of weeping lateral trench bottom required in Article 7A.1.1. when pressure distribution is used in accordance with Article 7A.1.9.,
3. supplied with effluent from an open bottom sand filter may have the required area of weeping lateral trench bottom in Clause 7A.1.3.(b) reduced by of the area of the sand filter, or
4. supplied with effluent from a septic tank may have a 20% reduction in the area of weeping lateral trench bottom required in Article 7A.1.1. when pressure distribution is used in accordance with Article 7A.1.9.

Reductions in disposal field sizing are enabled by providing additional treatment of the waste in sand filters and treatment plants. The higher quality effluent has less BOD₅ and TSS resulting in less loading of organic material and suspended solids on the soil interface in the disposal field. This lighter loading means the soil organisms quickly break down the organic loading on the soil. Without a substantial clogging mat being formed by the organic matter long term loading rates are significantly higher than in a disposal field receiving septic tank effluent.

Reductions in field size are also enabled by using pressure distribution laterals that provide the entire disposal field with effluent doses that are applied in a thin layer. In this way every dose of effluent is applied to the entire area of the soil in the disposal field utilizing all the soil microorganisms and maintaining healthy aerobic conditions. In this way the effluent is broken down and treated quickly. Higher long term loading rates are achieved.

Although not explicitly required, pressure distribution laterals should always be used when applying effluent from a sand filter or treatment plant. With high quality effluent, a clogging mat is not formed to slow the effluent before entering soil and may overload the first parts of the system for a long time reducing aerobic conditions and the treatment of pathogens.

See Pg. 31, Sentence 5.1.1. (d) regarding minimum septic tank size for systems using pressure effluent distribution.

See Pg. 44, Article 7A.1.9
See Pg. 57, Article 9.1.3

(a)

• where
  • Square Metres = trench bottom area in square metres not including trench walls
  • Litres per Day = expected sewage volume in litres/day
  • Percolation Rate = percolation rate in minutes/25 mm, or

(b)

• where
  • Square Feet = trench bottom area in square feet not including trench walls
  • Gallons per Day = expected sewage volume in gallons/day
  • Percolation Rate = percolation rate in minutes/inch.

Note: A Table of loading rates, square roots of percolation rates, and calculations using this formula is provided for convenience in the Appendix A.4.A.

Note: The percolation tests form only part of an acceptable site evaluation. Additional evaluation of the soil type, Sodium Adsorption Ratio (S.A.R.), clay content and type of clay (Table A.3.B. and Table A.3.C.), depth to impervious layer or water table, terrain, and other factors, must also be conducted.

See Pg. 89, Table A.4.A. in Appendix "A"

Typical examples:

Example: (Metric)

• 4 bedroom house = 2040 Litres per day
• Percolation Rate = 36 mins. per 25 mm
• Square Root of the Percolation Rate = 6
• Square metres of disposal field trench required = 149.92

Example: (Imperial)

• 4 bedroom house = 450 Gallons per day
• Percolation Rate = 36 mins. per inch
• Square Root of the Percolation Rate = 6
• Square feet of disposal field trench required = 1584.66
• Lineal ft. of weeping lateral using 2 ft. trench = 792.3 ft.

See Pg. 129, Sizing the Disposal Field Trench Bottom Area in Appendix "B"
See Pg. 149, Sizing the Infiltration Area in Appendix "B"

1. Clay, not suitable without further testing,
2. Silty Clay, not suitable without further testing,
3. Silty Clay Loam, not suitable without further testing,
4. Sandy Clay, not suitable without further testing,
5. Clay Loam, 10.78 L per square metre (0.22 gal per sq. ft.),
6. Silt, 12.25 L per square metre (0.25 gal per sq. ft.),
7. Sandy Clay Loam, 13.72 L per square metre (0.28 gal per sq. ft.),
8. Silt Loam, 13.72 L per square metre (0.28 gal per sq. ft.),
9. Loam, 17.15 L per square metre (0.35 gal per sq. ft.),
10. Sandy Loam, 22.05 L per square metre (0.45 gal per sq. ft.),
11. Loamy Sand, 30.87 L per square metre (0.63 gal per sq. ft.), and
12. Sand, not suitable without further testing.

Intent: Soils classed as not suitable without further testing for a disposal field in this table may have an infiltration rate that will accommodate a disposal field. Further testing such as a percolation test, soil structure, and determining the absence of expandable clays may indicate the soil can accommodate a disposal field.

See Pg. 37, Article 7.1.4
See Pg. 179, Fig. 7A.1.5.A. Soil Texture Classification Triangle in Appendix "B"

See Pg. 121, Particle or Grain Size Analysis Test in Appendix "B"
See Pg. 129, Sizing the Disposal Field Trench Bottom Area in Appendix "B" See Pg. 149, Sizing the Infiltration Area in Appendix "B"

To use these loading rates, divide the volume of sewage per day by the given loading rate. (Gallons per day divided by the gallon per sq. ft. loading rate for the soil texture.)

Example of sizing using soil texture loading rates:

4 bedroom house, Silt loam soil.

Example: imperial measures
450 gals per day
loading rate for silt loam = .28 gals. per sq. ft.
450 ÷ 0.28 = 1607.14 sq. ft.

1607.14 sq. ft. of trench bottom area is required for the four bedroom home on silt loam soil.

If 2 foot wide trenches are used 803.6 lineal ft. of disposal field trench is required.

Example: metric measures
2040 litres per day
loading rate for silt loam = .13.72 L per sq. m.
2040 ÷ 13.72 = 148.69 sq. meters

148.69 sq. meters of trench bottom area is required for the four bedroom home on silt loam soil.

Figure 7A.1.5.A. Soil Texture Classification Triangle

 

Note: Plotting the percentage of sand and clay provides the remaining percentage of silt.

See Pg. 179, Fig. 7.A.1.5.A. in Appendix "B" for a full page view of Figure 7.A.1.5.A.

Soil Texture Classification means a classification of soil set out in Table 7A.1.5 having a soil composition determined by Grain or Particle Size Analysis using a standard hydrometer method of establishing percentage of sand, silt or clay particles in a soil sample.

Grain or Particle Size Analysis means a standard hydrometer method of establishing percentage of sand, silt or clay particles in a soil sample.

The results of a Grain or Particle Size analysis will provide the percentages of Sand, Silt and Clay in the soil sample.

To use the table:
1. Apply the percentages of Sand to the bottom of Table 7A.1.5.A. and draw a vertical line up through the table,
2. Apply the percentages of Clay to the left side of Table 7A.1.5.A. and draw a horizontal line across the table.

Where the vertical and horizontal lines cross indicates a Soil Texture Classification that may be used with Article 7A.1.5. to obtain the maximum effluent loading rate in litres per m2 (gallons per square foot) per day of effluent to a weeping lateral trench bottom.

See Pg. 117, Soil Texture in Appendix "B"

Delivering a volume flush enhances distribution and assists in preventing freezing. Better distribution enhances treatment and extends the life of the system. In large systems splitting or sequential dosing should be considered.

See Pg. 104, Capacity of Effluent Chambers in Appendix "B"
See Pg. 135, Split Disposal Fields in Appendix "B"
See Pg. 182, Fig. DF 1B in Appendix "B"
See Pg. 184, Fig. DF 5 in Appendix "B"
See Pg. 185, Fig. DF 6 in Appendix "B"
See Pg. 187, Fig. DF 9 in Appendix "B"
See Pg. 188, Fig. DF 10 in Appendix "B"
See Pg. 189, Fig. DF 11 in Appendix "B"
See Pg. 191, Fig. DF 13 in Appendix "B"

7A.1.7. A disposal field shall not use serial distribution as a method to distribute effluent to weeping lateral trenches.

Intent: The effluent should be distributed to each lateral evenly. The effluent should not be allowed to flow through one weeping lateral trench to another weeping lateral trench at a lower elevation.

See Pg. 47, Article 7.A.2.7
See Pg. 134, Sloping Ground Systems Using Distribution Boxes in Appendix "B"

See Pg. 135, Sloping Ground Systems Using Bi-Level Crosses, in Appendix "B"

See Pg. 185, Fig.DF 6 in Appendix "B"
See Pg. 187, Fig. DF 9 in Appendix "B"
See Pg. 188, Fig. DF 10 in Appendix "B"

1. appropriate pressure head and capacity considering
   
   1. maximum static lift measured from the minimum effluent tank level to the level of the perforated distribution piping,
   2. pipe friction based upon a Hazen Williams coefficient of smoothness of 150, and
   3. orifice pressure head requirements,
      Note: Pipe friction loss tables can be found in the Appendix A.1.C. tables. Use these tables to determine the size of main effluent supply piping and distribution headers.
      
      
2. a minimum pressure head of 1500mm (5 ft.) at the most remote orifice with not more than a 10% flow variation between any orifices in an individual system,
3. distribution lateral piping sized as specified in Table A.1.A.,
4. orifices in the distribution laterals
   
   1. having a minimum diameter of 3.2 mm (1/8 in.),
   2. evenly spaced at a distance not greater than 1500mm (60 in.),
      
5. a volume per flush not exceeding 20% of the expected volume of sewage per day, and
   

   Intent: Numerous light applications of effluent provide better treatment conditions. The volumes per flush should be evenly spaced over a 24 hour day.
   

6. a screen to prevent particles greater than 3.2 mm ( in.) from entering the pump and being discharged into the distribution laterals, when distributing effluent from other than a packaged sewage treatment plant or sand filter.

A pressure effluent distribution system can be used in disposal fields and is required in Treatment Mounds and Sand Filters.

See Pg. 31, Sentence 5.1.1. (d) regarding minimum septic tank size for systems using pressure effluent distribution.

See Pg. 40, Article 7A.1.3. for possible reductions in weeping lateral trench bottom area when using pressure effluent distribution.

See Pg. 69, Table A.1.A. in Appendix "A".
See Pg. 98, Weeping Lateral Piping in Appendix "B".
S ee Pg. 138, Pressure Distribution
S ee Pg. 192, Fig. PDL 1 (pressure distribution)
See Pg. 194, Fig. PDL 3 (squirt test)

7A.2. Installation Standards

1. 1.5 m (5 ft.) from a property line,
2. 15 m (50 ft.) from a water source,
3. 15 m (50 ft.) from a water course,
4. 9 m (30 ft.) from a basement, cellar or crawl space,
5. 1 m (3.25 ft.) from a building that does not have a basement, cellar or crawl space, and
6. 1 m (3.25 ft.) from a septic tank or packaged sewage treatment plant.

Note: The 9 m (30 ft.) requirement to a cellar, basement or crawl space is intended to protect excavations below grade from accumulating migrating effluent. A crawl space that is not below grade, or where the level of the ground surface at the disposal area is below the level of the crawl space, would not require 9m (30 ft) clearance and could be treated as a building without a basement.

The horizontal distances required in this article are required to protect water sources in the event of failure of the systems and in recognizing that lateral flow of effluent can travel considerable distances before treatment is complete due to the layers of soil being formed in horizontal layers. The separations in the soil layers provides a path in which effluent can flow in saturated conditions. Under these conditions pathogens and nutrients are not effectively removed.

See Pg. 178, Fig. Vertical Separation in Appendix "B"
See Pg. 133, Location of Disposal Fields in Appendix "B"
See Pg. 38, Article 7.1.6. for Vertical Separation Requirements

1. the weeping lateral trenches are lined on the bottom and sides with a minimum of 300 mm (1 ft.) of a soil having a percolation rate in excess of 5 minutes per 25 mm (1 in.), or

   Intent: The trenches, when lined with loam or sandy loam soil having a percolation rate of 5 to 10 minutes/ 25mm (1 in.) will slow the rate the effluent enters the native soil, preventing saturated flow through the soil and allowing for it to be treated.

   Note: A disposal field shall not be installed in soils that have a percolation rate in excess of 60 minutes per inch as limited by Article 7.1.5.

2. sufficient test data is provided indicating that between a water table and the lowest point where effluent is discharged into the soil, there is a layer of soil over the entire area which
   1. has a minimum thickness of 300 mm (1 ft.), and
   2. has a percolation rate slower than 5 minutes per 25 mm (1 in.).

When using lined trenches due to fast percolation rates in the surrounding soil pressure distribution laterals should also be used to avoid the possibility that effluent will channel its way through the soil layer due to heavy loading at the start of the trench.

Soil used to line the trench should be a loamy sand which is the coarsest soil on which effluent can be applied as identified in 7A.1.5. Or alternatively the soil that is to be used to line the trench can be tested with a percolation test when in place or at the location it is obtained from.

The soil used to line the trench should not contain any significant amount of clay so that the soil does not become excessively packed when placed in the trench.

The purpose of the lined trench is to slow, not stop the movement of the effluent.

See Pg. 137, Lined Trenches For Porous Soils in Appendix "B"
See Pg. 138, Pressure Distribution, Coarse Soils
See Pg. 181, Fig. DF 1A in Appendix "B"
See Pg. 182, Fig. DF 1B in Appendix "B"

1. be not more than 900 mm (3 ft.) deep,
2. be not less than 450 mm (18 in.) or more than 900 mm (3 ft.) in width when using weeping lateral trench media,
3. be not less than 300 mm (12 in.) or more than 900 mm (3 ft.) in width when using chambers in weeping lateral trenches,
4. have a nominally level bottom,
5. include a void space created by
   1. a chamber, or
   2. weeping lateral trench media at the bottom of the trench filling the entire width of the trench to a depth of 300 mm (1 ft.), and
      
      
6. be provided with a minimum of 900 mm (3 ft.) of earth between it and another weeping lateral trench.

Note: A cover of 12 inches of soil over the top of the gravel and effluent pipe has been found to usually provide adequate protection from frost in many areas of Alberta.

See Pg. 126, Disposal Fields - General in Appendix "B"
See Pg. 127, Weeping Lateral Trenches in Appendix "B"
See Pg. 128, Chamber Type Disposal Fields in Appendix "B"
See Pg. 180, Fig. DF 1 in Appendix "B"
See Pg. 168, Fig. Tanks 2 in Appendix "B"

1. be laid nominally level at a maximum depth of 600 mm (2 ft.) measured from the top of the pipe to the ground surface, and
2. be installed with the top of the pipe at the top of the void space.

See Pg. 126, Disposal Fields - General in Appendix "B"
See Pg. 127, Weeping Lateral Trenches in Appendix "B"

See Pg. 128, Chamber Type Disposal Fields in Appendix "B"
See Pg. 180, Fig. DF 1 in Appendix "B"

See Pg. 133, Level Ground Systems in Appendix "B"
See Pg. 183, Fig. DF 2 in Appendix "B"
See Pg. 183, Fig. DF 3, in Appendix "B"
See Pg. 183, Fig. DF 4 in Appendix "B"
See Pg. 189, Fig. DF 11 in Appendix "B"

See Pg. 135, Sloping Ground Systems Using Bi-level Crosses in Appendix "B"
See Pg. 187, Fig. DF 9 in Appendix "B"
See Pg. 188, Fig. DF 10 in Appendix "B"
See Pg. 168, Fig. Tanks 2 in Appendix "B"

1. have an internal dimension not exceeding 300 mm (12 in.),
2. provide relatively equal distribution to all outlets, and ?
3. be readily accessible for inspection and service.

Intent: To ensure relatively equal distribution to all weeping laterals. The maximum internal dimension minimizes the impact on even distribution in the event of soil movement or frost heave tipping the box. Accessibility is required to confirm distribution during service.

See Pg. 184, Fig. DF 5 in Appendix "B"

See Pg. 134, Sloping Ground Systems Using Distribution Boxes in Appendix "B"

1. the disposal field may be installed on sloping ground,
2. the invert of the outlet piping to the next drop box shall be
   1. above the top of the weeping lateral pipe outlet, and
   2. a minimum of 25 mm (1 in.) below, the invert of the inlet piping to the drop box, and
3. the drop box serving each weeping lateral pipe shall have provision for preventing effluent from entering the weeping lateral pipe.

Intent: A drop box system is a form of an anaerobic effluent disposal system. It is intended to be used primarily in very porous soil structures where the creation of a restricting layer of biomat is desired. This biomat reduces the infiltration rate of effluent into the soil. This design is used to reduce infiltration rates where desired.

A drop box cannot be used as a "distribution box" for distributing effluent evenly to weeping lateral trenches.

See Pg. 134, Sloping Ground Systems Using Drop Boxes, in Appendix "B"
See Pg. 186, Fig. DF 7 in Appendix "B"
See Pg. 47, Fig. DF 8 in Appendix "B"

1. a roadway or driveway,
2. a paved area,
3. a vehicle parking lot,
4. any structure, or,
5. under a vegetable garden.

7A.3 Requirements for Materials

1. be materials that maintain structural integrity and will not be degraded by the environment created in the disposal field trench,
2. consist of 12 mm (½ in.) to 50 mm (2 in.) particle size material,
3. be able to withstand vertical and horizontal loads from backfill equal to a minimum of 1 m (3.25 ft.) of earth cover,
4. not contain more than 5% fines, silt or clay,
5. provide a minimum of 30% void volume under compression conditions equal to the weight of 1 m (3.25 ft.) of earth cover, and
6. be covered to prevent migration of soil particles into the void space around the media by
   1. 75 mm (3 in.) of a non-oil-seed straw, or other equivalent fibrous material, or
   2. a filter fabric.

See Pg. 98, Weeping Lateral Piping in Appendix "B"
See Pg. 127, Weeping Lateral Trenches in Appendix "B"
See Pg. 180, Fig. DF 1 in Appendix "B"
See Pg. 181, Fig. DF 1A in Appendix "B"

1. be placed across the full width of the trench and be
   1. a 300 mm (1 ft.) layer of gravel having a particle size of 12 mm (½ in.) to 40 mm (1½ in.), or
   2. a 150 mm (6 in.) layer of clean sand covered by a 150 mm (6 in.) layer of gravel having a particle size of 12 mm (½ in.) to 40 mm (1½ in.), and
2. not contain more than 5% fines, silt or clay.

Note: The requirements of Article 7A.3.1. also apply.

See Pg. 98, Weeping Lateral Piping in Appendix "B"

See Pg. 127, Weeping Lateral Trenches in Appendix "B"
See Pg. 180, Fig. DF 1 in Appendix "B"
See Pg. 181, Fig. DF 1A in Appendix "B"

1. not smaller than nominal 25 mm (1 in.) and not larger than nominal 50 mm (2 in.) in size,
2. washed free of iron, fines and dust,
3. compacted to the elevation of the invert of the piping, and
4. covered with a filter fabric prior to back filling the trench with earth.

Note: The requirements of Article 7A.3.1. also apply.

Intent: Materials such as gravel or tires are accepted materials that meet the requirements of Article 7A.3.1. Other materials may also be acceptable provided they meet the criteria of 7A

See Pg. 98, Weeping Lateral Piping in Appendix "B"
See Pg. 127, Weeping Lateral Trenches in Appendix "B"
See Pg. 180, Fig. DF 1 in Appendix "B"
See Pg. 181, Fig. DF 1A in Appendix "B"

1. be smooth, rigid plastic piping, and
2. be certified for a pressure application by a testing agency recognized by the Standards Council of Canada, or acceptable to an Administrator.

See Pg. 93, Table A.5.A. Piping Materials in Appendix "A"
See Pg. 69, Table A.1.A. , Pressure Distribution Lateral Tables in Appendix "A"

7B Chamber System Disposal Fields

7B.1 Design Standards

1. may be calculated using 1.6 times the actual width of the chamber, and
2. the calculated width shall not exceed 900mm (36in.).

Note: The excavation for a trench using chambers should be equivalent to 1.6 times the width of the chamber to provide an area of disturbed earth equivalent to a gravel filled trench.

For example: A system requires 875 square ft. of trench bottom absorption area.

Gravel trenches - 438 ft long x 2ft wide = 876 square ft.

Chamber system - 438 ft. long x15 in. (or 1.25 ft.) (actual chamber width) X 1.6 = 876 square ft..

See Pg. 49, Article 7B.1.3
See Pg. 128, Chamber Type Disposal Fields in Appendix "B"

Example:

system requires 900 sq. ft of trench bottom area,

Length of 2 ft. wide trench using gravel filled trenches = 450 lineal feet.

Length of 15 inch (1.25 ft.) wide chamber = 450 lineal feet.

(1.25 x 1.6 x 450 = 900 sq. ft.)

7B.2 Installation Standards

See Pg. 128, Chamber Type Disposal Fields in Appendix "B"
See Pg. 184, Fig. DF 5 in Appendix "B"
See Pg. 185, Fig. DF 6 in Appendix "B"

1. splash pans supplied by the manufacturer,
2. a minimum of 100 mm (4 in.) of gravel in the most upstream 3 m (10 ft.) portion of all weeping lateral trenches or other area that receives effluent, or
3. other suitable means to dissipate the hydraulic energy of the effluent it is receiving and prevent erosion or disturbance of the trench bottom.

Intent: To prevent erosion or disturbance of the trench bottom by the effluent that spills into the chamber rather than being piped the entire length of the chamber lateral.

See Pg. 128, Chamber Type Disposal Fields in Appendix "B"

7B.3 Material Requirements