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44 <br />3. Minimum Seepage Area (total flat bottom of trenches) <br />of the purification field shall be determined by one of the fol- <br />lowing methods: <br />(a) Recommendation based upon experience data, in which <br />case requirements shall be stated on a basis of square <br />feet of absorptive area per bedroom rather than lineal <br />feet of tile. <br />(b) Results of actual percolation tests conducted on the site <br />of proposed purification field. Such tests shall be made <br />by the owner under the direct supervision of the Health <br />Department and in accordance with a standard pro- <br />cedure as recommended by the Virginia State Health <br />Department. <br />(c) Determination of absorptive area from results of per- <br />colation tests shall be in accordance with the following <br />table: <br />Average Time In Minutes <br />Effective Absorption Area (Area in <br />For Water Level to Lower <br />bottom of disposal trench) in Square <br />One Inch <br />Feet per Bedroom or per 100 gal. per <br />(d) Septic tanks shall be of poured -in-place concrete, or <br />day of estimated water use <br />10 minutes or less <br />130 <br />11-20 minutes <br />170 <br />21-30 minutes <br />210 <br />31-40 minutes <br />250 <br />41-50 minutes <br />290 <br />51-60 minutes <br />330 <br />Over 60 minutes <br />Unsuitable for subsurface drainage <br />Minimum installation <br />shall be for a two-bedroom house. <br />4. Construction shall be in accordance with the following <br />specifications: <br />(a) All trenches in a purification field shall be the same <br />width and length, and the following standards shall be <br />required: <br />1. Minimum number of lines per field ........ _. 2 <br />2. Maximum length of individual lines 100 ft. <br />3. Minimum bottom width of trench ................... 18 in. <br />4. Maximum depth of cover of tile lines .............. 24 in. <br />5. Preferred depth of cover of tile lines .............. 16 in. <br />6. Grade of tile lines ............ ...... 2" to 4" per 100 feet <br />7. Space of trenches ........................ At least 6 feet apart <br />8. Minimum filter material under tile .................... 6 in. <br />9. Minimum filter material over tile .................... - 2 in. <br />(b) Pipe used for the lines between the septic tank and <br />distribution box, on all lines within 10 feet of dwelling, <br />under paved areas and on all main laterals from dis- <br />tribution box in fields constructed on sloping ground, <br />shall be bell and spigot type of vitrified clay with water- <br />tight joints. Pipe used under driveways or other areas <br />subject to heavy loads shall be bell and spigot cast iron <br />with leaded joints. Such sections laid in the purification <br />field shall not be considered in determining the effective <br />absorption area. <br />(c) Field tile used in the purification field shall be not less <br />than 4 inches in diameter and shall be laid with 1/.1 inch <br />open joints. <br />(1) All open joints shall be protected on top by strips <br />of asphalt -treated building paper at least 10 inches <br />long and 3-6 inches wide. <br />(2) All bends used in the purification field shall have <br />a watertight joint at each end of the bend. <br />(d) Filter material shall be hard and durable, of crushed <br />stone, gravel slag, or similar material. <br />(1) Such material may vary from 1/1 to 3 inches in size. <br />(e) Grade boards, securely staked in the bottom of the <br />trench, or other means approved by the Health Depart- <br />ment, shall be provided to insure that the pipes shall <br />be laid with a grade of 2 inches to 4 inches per hundred <br />feet. <br />22.1-19. Notification of Corrections to Be Made. <br />If, upon any inspection the Health Director or his authorized <br />agent, shall find any violation of this section and/or the pro- <br />visions of the permit issued under it, he shall direct the per- <br />son, firm or corporation to whom the permit was issued, by <br />(d) Subsurface Purification Field. <br />1. Location of the purification field should be in an unob- <br />structed and unshaded area, and the distance given shall be • <br />the minimum which the disposal field can be located from the <br />following: <br />(a) Any water supply (except as noted below) ...... 50 feet <br />(b) Streams............................................................. 25 feet <br />(c) Dwellings .. .................. ......................... ...... 10 feet <br />(d) Large Trees .... ......... .. ................ _ 10 f eet • <br />(e) Property Lines .................... 10 feet <br />2. Distribution box of sufficient size to accommodate the <br />necessary field lateral lines shall be constructed at the head of <br />each purification field. <br />(a) Each field lateral line shall be connected separately to <br />the distribution box and shall not be subdivided. <br />(b) The invert of all outlets shall be level and the inlet <br />invert shall be at least 1 inch above the outlets. <br />3. Design of the septic tank shall be rectangular in shape <br />and the length shall not be less than twice nor more than three <br />times the width. The liquid depth shall be not less than four <br />feet and the freeboard or airspace shall not be less Than one <br />foot. <br />7 c <br />4. Liquid capacity of all septic tanks shall be based upon <br />the number of bedrooms contemplated in the building served <br />and shall conform to Table I herein shown. <br />TABLE h -CAPACITY OF SEPTIC TANK <br />into the septic tank and thence through the main build- <br />ing stack. <br />(d) Septic tanks shall be of poured -in-place concrete, or <br />Capacity <br />precast concrete, or brick wall 71 /" thick with 1/�" <br />, <br />parging on inside. <br />Septic Tank <br />(1) Concrete septic tanks, poured -in-place, shall be <br />B <br />poured with a standard concrete mixture of 1-2-3 <br />D ;r <br />or 1-2-4 mix. Where the excavation is subject to <br />Gallons <br />caving, or where the water table is objectionably <br />Width <br />high, outside forms and pumping will be required <br />3 or less <br />in order to assure a watertight tank. The walls, <br />7'0" <br />top and bottom of the tank are to be not less than <br />1110" <br />4" thick, as shown on plans; top and manhole cover <br />4 <br />to be reinforced with reinforcing steel, as shown <br />81,0" <br />on plans. <br />110" <br />(2) Precast concrete tanks shall be of a design as <br />5 <br />shown on plan, and size as stated on permit, and <br />910" <br />,. made` with a standard 1-2-3 mixture. The walls <br />11,0" <br />shall be not less than 21/.1" in thickness, reinforced <br />6 <br />with No. 9 steel placed as shown on plan. <br />` <br />(d) Subsurface Purification Field. <br />1. Location of the purification field should be in an unob- <br />structed and unshaded area, and the distance given shall be • <br />the minimum which the disposal field can be located from the <br />following: <br />(a) Any water supply (except as noted below) ...... 50 feet <br />(b) Streams............................................................. 25 feet <br />(c) Dwellings .. .................. ......................... ...... 10 feet <br />(d) Large Trees .... ......... .. ................ _ 10 f eet • <br />(e) Property Lines .................... 10 feet <br />2. Distribution box of sufficient size to accommodate the <br />necessary field lateral lines shall be constructed at the head of <br />each purification field. <br />(a) Each field lateral line shall be connected separately to <br />the distribution box and shall not be subdivided. <br />(b) The invert of all outlets shall be level and the inlet <br />invert shall be at least 1 inch above the outlets. <br />3. Design of the septic tank shall be rectangular in shape <br />and the length shall not be less than twice nor more than three <br />times the width. The liquid depth shall be not less than four <br />feet and the freeboard or airspace shall not be less Than one <br />foot. <br />7 c <br />4. Liquid capacity of all septic tanks shall be based upon <br />the number of bedrooms contemplated in the building served <br />and shall conform to Table I herein shown. <br />TABLE h -CAPACITY OF SEPTIC TANK <br />5. Construction of the tank shall be such as to assure its <br />being water -tight and prevent the entrance of rain water or <br />surface drainage. <br />(a) The tank shall be constructed of sound and durable <br />material not subject to excessive corrosion or decay. <br />(b) Adequate access to each compartment of the tank, for <br />inspection and sludge removal, shall be provided by a <br />manhole or removable cover. <br />Where the top of the tank is located more than 24 <br />inches below the surface of the ground, manholes shall <br />be built up to within 12 to 18 inches of the surface. <br />(c) Inlet and outlet connections shall be submerged to in- <br />sure the least possible disturbance in the tank. <br />The inlet pipe shall extend into the tank at the flow <br />line and be connected to a tee connection extending six <br />inches (6") above and six inches (6") below the flow <br />line. The outlet tee connection shall extend six inches <br />(6") above the flow line and two feet (2') below the <br />flow line. Satisfactory venting of the tank shall be <br />provided through the inlet and main building stack. <br />The outlet shall be similarly vented to provide proper <br />ventilation of the disposal field or seepage pits back <br />• <br />Potential Capacity <br />Capacity <br />Of <br />Dimensions of Septic Tawk <br />of Home <br />Septic Tank <br />A <br />B <br />C <br />D ;r <br />No. of Bedrooms <br />Gallons <br />Length <br />Width <br />Air Space Liquid Depth <br />3 or less <br />720 <br />7'0" <br />316" <br />1110" <br />4'0" <br />4 <br />1000 <br />81,0" <br />4'0" <br />110" <br />4'0" <br />5 <br />1250 <br />910" <br />4'6" <br />11,0" <br />4'3" <br />6 <br />1480 <br />9'6" <br />4'8" <br />1'3" <br />416" , <br />7 <br />1720 <br />10'0" <br />5'0" <br />1'3" <br />4'8" <br />5. Construction of the tank shall be such as to assure its <br />being water -tight and prevent the entrance of rain water or <br />surface drainage. <br />(a) The tank shall be constructed of sound and durable <br />material not subject to excessive corrosion or decay. <br />(b) Adequate access to each compartment of the tank, for <br />inspection and sludge removal, shall be provided by a <br />manhole or removable cover. <br />Where the top of the tank is located more than 24 <br />inches below the surface of the ground, manholes shall <br />be built up to within 12 to 18 inches of the surface. <br />(c) Inlet and outlet connections shall be submerged to in- <br />sure the least possible disturbance in the tank. <br />The inlet pipe shall extend into the tank at the flow <br />line and be connected to a tee connection extending six <br />inches (6") above and six inches (6") below the flow <br />line. The outlet tee connection shall extend six inches <br />(6") above the flow line and two feet (2') below the <br />flow line. Satisfactory venting of the tank shall be <br />provided through the inlet and main building stack. <br />The outlet shall be similarly vented to provide proper <br />ventilation of the disposal field or seepage pits back <br />• <br />