Construction and Operation Standards
10. (1) The following are prescribed as standards for the construction and installation of a Class 4 sewage system: 1. The septic tank shall conform to the requirements of section 6. 2. The working capacity of the septic tank shall in no case, be less than 2,700 litres and, i. where the septic tank system is to be used in connection with a private dwelling having the number of bedrooms itemized in Column 1 of Table 2, shall be not less than the number of litres set out opposite thereto in Column 2, or ii. where the septic tank system is to be used in connection with structures other than a private dwelling having five bedrooms or less, shall be not less than twice the daily sewage flow for daily sewage flows of 3,600 litres or less and not less than three-quarters of the daily sewage flow plus 4,500 litres for daily sewage flows in excess of 3,600 litres. 3. The septic tank shall be of such construction and design as will permit the collection and holding of sewage therein to a depth of not less than 120 centimetres except that a depth of not less than ninety centimetres is permissible where excavation in rock is necessary or to avoid rupture or displacement of the tank due to ground water pressure. 4. The septic tank shall be constructed in such a manner that any sewage flowing through the tank shall pass through at least two compartments for settling sewage. 5. The working capacity of the second compartment of a septic tank shall be approximately 50 per cent of the working capacity of the first compartment. 6. Partitions separating the septic tank into compartments shall extend at least fifteen centimetres above the liquid level at the outlet and there shall be one or more openings through or above the partition which openings shall have a total area of at least three times the area of the inlet pipe and be located between the ceiling and a level fifteen centimetres above the liquid level at the outlet to provide for the free flow of air between compartments. 7. Sewage may pass from one compartment to another of the septic tank system by means of either, i. a fixture similar to that described in Standard CAN3- B66 for outlet devices, or ii. through two or more openings through the partition located in a horizontal line and evenly spaced across the width of the partition, centred at approximately 40 per cent of the liquid depth below the surface of the liquid, and having a total area of between three and five times that of the cross-sectional area of the inlet pipe. 8. Where the total length of distribution pipe required by subsection (3) is 150 metres or more, the sewage system shall have a pump or siphon, contained in a separate compartment that may be part of the tank structure, so designed and constructed that it will be capable of discharging from the compartment, within a time period not exceeding fifteen minutes, a volume of tank effluent not less than three-quarters of the total interior volume of the distribution pipe. 9. No person shall locate or permit the location of a septic tank closer to an item set out in Column 1 of Table 3 than the horizontal distance set out opposite thereto in Column 2. (2) The following are prescribed as standards for the construction of a leaching bed used in connection with a Class 4 sewage system: 1. No person shall locate or permit the location of the leaching bed, i. in an area that has an average slope that exceeds one unit vertically to four units horizontally, ii. in soil that has a percolation time greater than fifty minutes or less than one minute, iii. so that a distribution pipe installed therein or any part thereof is closer to an item set out in Column 1 of Table 4 than the horizontal distance set out opposite thereto in Column 2, iv. where the effluent from the leaching bed would cause impairment of the ground water, or v. in or on an area subject to flooding that may be expected to cause damage to the leaching bed or a public health nuisance by impairing the operation of the leaching bed. 2. The surface of the leaching bed shall be shaped to shed water and, together with the side slopes of any raised portion, shall be protected against erosion in such a manner as to not inhibit the evaporation and transpiration of waters from the soil and to not cause plugging of the distribution pipe. 3. The leaching bed shall not be covered with any impervious material. 4. The leaching bed shall be protected from compaction or any stress or pressure that may result in the impairment or destruction of any pipe or tile in the leaching bed. (3) The following are prescribed as standards for the construction of a leaching bed, constructed by means of absorption trenches, that is used in connection with a Class 4 sewage system: 1. The leaching bed serving a private dwelling having the number of bedrooms set out in Column 1 of Table 5 shall have a distribution pipe having a total length not less than that set out opposite such number in the column headed by the design percolation time for the soil in the leaching bed. 2. The leaching bed serving a building or structure other than a private dwelling shall have a total length of distribution pipe not less than the value determined by the formula, L = QT/200 where L is the total length of distribution pipe expressed in metres, Q is the total daily sewage flow in litres and T is the design percolation time in minutes, but in no case shall the total length of distribution pipe be less than forty metres. 3. The absorption trenches shall be, i. not more than thirty metres in length, ii. approximately the same length, iii. at least 0.5 metres in width, iv. between 0.6 and 0.9 metres in depth, v. centred at least 1.6 metres apart, vi. set at an elevation such that the bottom of the trench shall be at all points at least 0.5 metres above high ground water table and at least 0.9 metres above the maximum elevation of rock or soil with a percolation time of greater than fifty minutes, and vii. backfilled, after installation of distribution pipe in accordance with paragraph 4, with porous soil so as to ensure that after the soil settles the surface of the leaching bed will not form any depressions. 4. Distribution pipe used in the construction of a leaching bed shall be, i. of not less than three inch diameter trade size for gravity flow systems or one and one-quarter inch diameter trade size for pressurized systems, ii. placed or installed on a layer or covering at least 0.15 metres in depth and 0.5 metres in width comprised of stone that is either nineteen millimetre clear aggregate, washed to be free of fine material, or clean gravel screened to be between nineteen and fifty-three millimetres in size, iii. placed or installed with a uniform downward slope from the inlet with a drop of not less than thirty millimetres and not more than fifty millimetres for each ten metres of its length, iv. where it is open-jointed distribution pipe, installed in such a manner that there is an open space of not less than six and not more than twelve millimetres between each pipe or tile and that the upper half of every open space is covered with tar paper so as to prevent soil, gravel or other foreign matter from entering the distribution pipe through the open space, and v. covered with stone of the type used below the distribution pipe to a height of at least fifty millimetres above the top of the distribution pipe, which stone is then completely covered with untreated building paper, pea gravel, straw or other like material in such a manner as to prevent soil from entering the stone. 5. A leaching bed comprising absorption trenches may be constructed in imported soil provided that, i. there is unsaturated soil having a percolation time not less than one minute and not more than fifty minutes, to a depth of at least 0.25 metres over the area covered by the leaching bed and extending for at least fifteen metres beyond the outer distribution pipes in any direction in which the sewage entering the soil will move laterally, ii. where soil is added to meet the requirements of subparagraph i it shall be stabilized against erosion, iii. where the soil meeting the requirements of subparagraph i has percolation time greater than fifteen minutes, any soil added to it, except porous soil added as backfill above the stone layer in which the distribution pipe is located, has a percolation time not less than 75 per cent of the percolation time of the soil meeting the requirements of subparagraph i, iv. the site to which the soil is added is generally clear of vegetation, v. the soil that is added is compacted in layers so as to avoid uneven settlement of the distribution pipes, vi. the surface of the soil that is added to form the leaching bed and is above the level of the surrounding ground is extended horizontally at least one metre beyond the centre line of any pipe or the end of any absorption trench or part thereof before sloping to ground level, vii. the sides of the added soil are sloped to ensure stability but are not steeper than one unit vertically to two units horizontally, viii. any distribution boxes, header lines, absorption trenches and distribution pipe are constructed or installed only after the soil that has been added to the site has been compacted in accordance with subparagraph v, and ix. the distances set out in Column 2 of Table 4 are increased by two metres for each metre that the surface of the leaching bed is raised above ground level. 6. Soil added to meet the requirements of subparagraph i of paragraph 5 or to form the leaching bed, shall be regarded as part of the sewage system for the purposes of section 5. (4) A leaching bed used in connection with a Class 4 sewage system may be constructed as one or more filter beds if, (a) the requirements of subsection (2), paragraphs 4 and 6 of subsection (3) and subparagraphs i to v, viii and ix of paragraph 5 of subsection (3) are met; (b) the daily sewage load to the leaching bed does not exceed 5,000 litres; (c) the effective area of the surface of the filter medium in each filter bed is at least ten square metres and not more than fifty square metres; (d) where the leaching bed is serving a private dwelling with the number of bedrooms set out in Column 1 of Table 6, the area of the filter medium in the leaching bed is not less than that set out opposite the appropriate number of bedrooms in the column for Class 4 sewage systems; (e) where the daily sewage flow to the leaching bed does not exceed 3,000 litres, the area is such that the loading on the surface of the filter medium does not exceed 75 litres per square metre per day; (f) where the daily sewage flow to the leaching bed exceeds 3,000 litres, the area is such that the loading on the surface of the filter medium does not exceed 50 litres per square metre per day and the leaching bed is comprised of more than one filter bed, each of similar size and adjacent to each other; (g) where there is more than one filter bed in a leaching bed, the filter beds are separated so that there are at least five metres between the distribution pipes of each filter bed and those of all other filter beds; (h) the surface of the filter medium to which the sewage is applied is at least 0.5 metres above the high ground water table and at least 0.9 metres above the maximum elevation of rock or soil with a percolation time greater than fifty minutes; (i) the stone layer in which the distribution pipe is set is continuous over the surface of the filter medium to which the sewage is applied; (j) the lines of distribution pipe are evenly spaced over the surface of the filter medium to which the sewage is applied at a spacing not exceeding 1.2 metres; (k) the distance between, (i) the edge of the stone layer in which the distribution pipe is set, and (ii) the end of any distribution pipe and the center line of the outermost distribution pipe, shall, where there is more than one line of distribution pipe, be approximately one-half of the distribution pipe spacing but, in any event, shall not be less than 0.2 metres or more than 0.6 metres; (l) the filter medium has a minimum depth of 0.75 metres below the stone layer and is clean sand comprised of particles ranging in size between the limits of, (i) an effective size of 0.25 millimetres with a uniformity coefficient not less than 3.5, and (ii) an effective size of 2.5 millimetres with a uniformity coefficient not greater than 1.5, and having a uniformity coefficient not greater than 4.5; (m) the base of the filter medium extends at a thickness of at least 0.25 metres over an area meeting the requirements of the formula: A = QT/850 where A is the area of contact in square metres between the base of the filter medium and the underlying soil, Q is the daily sewage flow in litres and T is the percolation time of the underlying soil; (n) the filter bed is overfilled with porous soil so as to ensure that after the soil settles the surface of the bed will be shaped to shed rain-water. (5) The following are prescribed as standards for the operation of a Class 4 sewage system: 1. The owner of the sewage system shall arrange for the servicing and maintenance of all components of the sewage system as required to ensure its continued proper operation. 2. If the sewage system is a Class A sewage system, the owner shall at least once in every twelve months in which the system is used have it inspected by a person licensed to carry out servicing and repairs. R.R.O. 1990, Reg. 358, s. 10. class 5 sewage systems — holding tanks