Section R317-4-14 - Appendices(1) Appendix A. Septic Tank Construction. (a) Plans for each septic tank or underground holding tank shall be submitted to the division for approval. Such plans shall show all dimensions, capacities, reinforcing, maximum depth of soil cover, and such other pertinent data as may be required. Each tank shall conform to the design drawing and shall be constructed under strict, controlled supervision by the manufacturer. (i) Each precast reinforced concrete tank shall conform to the following: (A) The walls and base of each precast tank shall be securely bonded together and the walls shall be of monolithic or keyed construction.(B) The sidewalls and bottom of such a tank shall be at least 3 inches in thickness.(C) The top shall have a minimum thickness of 4 inches.(D) Each tank shall have reinforcing of at least 6 inch x 6 inch No. 6, welded wire fabric, or equivalent. Exceptions to this reinforcing requirement may be considered by the division based on an evaluation of acceptable structural engineering data submitted by the manufacturer.(E) All concrete used in each precast tank shall be Class A, at least 4,000 pounds per square inch, and shall be vibrated or well-rodded to minimize honeycombing and to assure water tightness.(F) Precast sections shall be set evenly in a full bed of sealant. If grout is used it shall consist of two parts plaster sand to one part cement with sufficient water added to make the grout flow under its own weight.(G) Any excessively mortared joint should be trimmed flush.(H) The inside and outside of each mortar joint shall be sealed with a waterproof bituminous sealing compound.(I) For early reuse of forms, the concrete may be steam cured. Other curing by water spraying or a membrane curing compound may be used and shall comply to best acceptable methods as outlined in Guide to Curing Concrete, ACI308R-01, by American Concrete Institute, Farmington Hills, Michigan.(ii) Each poured-in-place concrete septic tank shall conform to the following:(A) The top of each poured-in-place septic tank with a liquid capacity of 1,000 to 1,250 gallons shall be a minimum of 4 inches thick, and reinforced with 3/8 inch reinforcing rods 12 inches on center both ways, or equivalent.(B) The top of each tank with a liquid capacity of greater than 1,250 gallons shall be a minimum of 6 inches thick, and reinforced with 3/8 inch reinforcing rods 8 inches on center both ways, or equivalent.(C) The walls and floor shall be a minimum of 6 inches thick. The walls shall be reinforced with 3/8 inch reinforcing rods 8 inches on center both ways, or equivalent. Inspections by the regulatory authority may be required of the tank reinforcing steel before any concrete is poured.(D) A 6 inch water stop shall be used at the wall-floor juncture to ensure water tightness.(E) All concrete used in poured-in-place tanks shall be Class A, at least 4,000 pounds per square inch, and shall be vibrated or well-rodded to minimize honeycombing and to ensure water tightness.(F) Curing of concrete shall comply with the requirements in Subsection R317-4-14(1)(a)(i)(II).(iii) Each fiberglass tank shall conform to the following: (A) Each fiberglass tank shall comply with one of the following criteria for acceptance: (I) The Interim Guide Criteria for Glass-Fiber-Reinforced Polyester Septic Tanks, International Association of Plumbing and Mechanical Officials Z1000-2007. The identifying seal of the International Association of Plumbing and Mechanical Officials shall be permanently embossed in the fiberglass as evidence of compliance.(II) Manufactured to meet the structural requirements of Underwriters Laboratories (UL) Standard 1316.(III) Professionally engineered plans demonstrating compliance to tank configuration requirements of this rule including acceptable structural calculations or other pertinent data as may be required.(B) Each inlet or outlet tee shall be attached to the tank by a rubber or synthetic rubber ring seal and compression plate, or in some other manner approved by the division.(C) Each tank shall be installed in accordance with the manufacturer's recommendations.(iv) Each polyethylene tank shall conform to the following: (A) Each polyethylene tank shall comply with the criteria for acceptance established in Prefabricated Septic Tanks and Wastewater Holding Tanks, Can 3-B66-10 by the Canadian Standards Association, Ontario, Canada.(B) Each inlet or outlet tee shall be attached to the tank by a rubber or synthetic rubber ring seal and compression plate, or in some other manner approved by the division.(C) Each tank shall be installed in accordance with the manufacturer's recommendations.(b) Each prefabricated or precast tank that is commercially manufactured shall be plainly, legibly, and permanently marked or stamped with:(i) the manufacturer's name and address, or nationally registered trademark;(ii) the liquid capacity of the tank in gallons on the exterior at the outlet end within 6 inches of the top of the wall; and(iii) the inlet and outlet of all such tanks shall be plainly marked as "IN" or "OUT" respectively.(c) Each inlet, outlet, or tank compartment shall meet the minimum diameter requirements for building sewers.(i) Only one inlet or outlet is allowed, unless preauthorized by the regulatory authority.(ii) An inlet and outlet shall be located on opposite ends of each tank. (A) The invert of flow line of the inlet shall be located at least 2 inches, above the invert of the outlet to allow for momentary rise in liquid level during discharge to the tank.(B) An approved tank with offset inlets may be used when approved by the regulatory authority.(iii) Each inlet and outlet shall have a baffle or sanitary tee. (A) An inlet baffle or sanitary tee of wide sweep design shall be provided to divert the incoming wastewater downward. This baffle or tee is to penetrate at least 6 inches below the liquid level, but the penetration is not to be greater than that allowed for the outlet device.(B) For each tank with vertical sides, the outlet baffle or sanitary tee shall extend below the liquid surface a distance equal to about 40% of the liquid depth. For each horizontal cylindrical tank or tank of any other shape, that distance shall be reduced to about 35% of the liquid depth.(C) Each baffle shall be constructed from sidewall to sidewall or shall be designed as a conduit.(D) Each sanitary tee shall be permanently fastened in a vertical, rigid position.(iv) Each inlet and outlet pipe connection to the septic tank shall be sealed and adhere to the tank and pipe to form a watertight connection with a bonding compound or sealing ring.(v) Any inlet or outlet device may not include any design feature preventing free venting of gases generated in the tank or absorption system back through the roof vent in the building plumbing system. The top of each baffle or sanitary tee shall extend at least 6 inches above the liquid level to provide scum storage, but no closer than 1 inch to the inside top of the tank.(d) Liquid depth of each tank shall be at least 30 inches. Depth greater than 72 inches may only be considered in calculating liquid volume required in Subsection R317-4-6(7) if the tank length is at least two times the liquid depth.(e) The maximum burial depth shall be stated on the plans submitted.(f) Any septic tank may be divided into compartments provided the tank meets the following:(i) The volume of the first compartment shall equal or exceed two-thirds of the total required septic tank volume.(ii) No compartment may have an inside horizontal dimension less than 24 inches.(iii) Each inlet or outlet shall be designed as specified for tanks, except that when a partition wall is used to form a multi-compartment tank, an opening in the partition may serve for flow between compartments provided the minimum dimension of the opening is 4 inches, the cross-sectional area is not less than that of a 6 inch diameter pipe (28.3 square inches), and the mid-point is below the liquid surface a distance about equal to 40% of the liquid depth of the tank.(g) Scum storage volume shall consist of 15% or more of the required liquid capacity of the tank and shall be provided in the space between the liquid surface and the top of inlet and outlet devices.(h) Adequate access to each tank shall be provided to facilitate inspection, servicing and maintenance, and shall have no structure or other obstruction placed over it and shall conform to the following requirements: (i) Access to each compartment of any tank shall be provided through properly placed manhole openings not less than 18 inches in diameter, in minimum horizontal dimension or by an easily removable lid section.(ii) Each access cover shall be designed and constructed in such a manner that it may not pass through the access openings, and when closed shall be child-proof and prevent entrance of surface water, dirt, or other foreign material, and seal the odorous gases in the tank. Each concrete access cover for a manhole opening shall have adequate handles.(iii) Access to each inlet or outlet device shall be provided through a properly spaced opening not less than 12 inches in minimum horizontal dimension or by an easily removable lid section.(2) Appendix B. Pressure Distribution, Pumps, Controls, and Alarms.(a) Each absorption system designed to use pressure distribution shall conform to the following: (i) Pressure distribution design shall generally be based on the Utah Guidance for Performance, Application, Design, Operation and Maintenance: Pressure Distribution Systems document with the following exceptions:(A) Design and equipment shall emphasize ease of maintenance, longevity, and reliability of components and shall be proven suitable by operational experience, test, or analysis, acceptable to the regulatory authority.(B) Electrical disconnects shall be provided that are appropriate for the installation and shall have gas-tight junction boxes or splices. Each electrical component used in an onsite wastewater system shall comply with applicable requirements of the State of Utah Electrical Code.(C) Each component shall be constructed and installed to facilitate ease of service without having to alter any other part.(ii) Before final approval for operation, each pump, control and related apparatus shall be field tested and found to operate as designed. (A) When a duplex pump system is designed, controls shall be provided that an alarm shall signal when one of the pumps malfunctions.(B) Where multiple pumps are operated in series, controls shall be installed to prevent the operation of a pump or pumps preceding a station that experiences a high level alarm event.(C) Controls shall be capable of controlling all functions incorporated or required in the design of the system.(I) The control panel for each pressure distribution system shall include a pump run-time hour meter and a pump event counter or other acceptable flow measurement method.(II) The control panel shall be installed within sight of the access risers. An other location may be approved by the regulatory authority.(III) Supporting hydraulic calculations and pump curve analysis shall be submitted to the regulatory authority with the design.(3) Appendix C. Soil Exploration Pits, Soil Logs, Soil Evaluations. (a) Soil conditions shall be obtained from a soil exploration pit dug to a depth of 10 feet in the absorption area, or to the ground water table if it is shallower than 10 feet below ground surface. If an absorption system excavation will be deeper than 6 feet, the soil exploration pit shall extend to a depth of at least 4 feet below the bottom of the proposed absorption system excavation. Each soil exploration pit shall be constructed in a manner to reduce potential for physical injury. One end of each pit should be sloped gently or "stair-stepped" to permit easy entry if necessary.(b) The soil log shall contain the following information.(i) A signed statement certifying that the log was evaluated and recorded in accordance with this rule.(ii) The names of all qualified individuals per Rule R317-11 conducting the tests.(iii) The location of the property.(iv) The location of the soil exploration pit on the property.(vi) A description and depths of the soil horizons throughout the soil exploration pit to include: (A) soil texture and structure using the USDA system of classification;(B) estimated volume percentage of coarse fragments defined as: (I) "Gravel" means a rock fragment from 0.1 inches to 3 inches in diameter;(II) "Cobble" means rock fragment from 3 inches to 10 inches in diameter;(III) "Stone" means a rock fragment greater than 10 inches in diameter;(C) the presence and abundance of mottling defined as:(I) "Few" when less than 2% of the exposed surface is occupied by mottles;(II) "Common" when from 2% to 20% of the exposed surface is occupied by mottles; and(III) "Many" when more than 20% of the exposed surface is occupied by mottles;(D) depth to groundwater or bedrock, if encountered, and maximum anticipated groundwater table; and(E) any other pertinent information.(c) Soils shall be evaluated using the USDA Soil Texture Classification method. The soil horizon with the lowest loading rate shall be used in calculating the required absorption area.(4) Appendix D. Percolation Method.(a) Each percolation test shall be completed by an individual certified per Rule R317-11 and shall be conducted in accordance with the instructions in this appendix.(b) When a percolation test is conducted, the test shall be conducted at a point and elevation selected as typical of the area in which the absorption system shall be located.(c) Percolation test results shall be submitted on a signed "Percolation Test Certificate". The test certificate shall contain the following:(i) A signed statement certifying that the test was conducted in accordance with this rule.(ii) The names of all individuals per Rule R317-11 conducting the test.(iii) The location of the property.(iv) The location of the percolation test on the property.(v) The depth to the bottom of the percolation test hole from the existing grade.(vi) The final stabilized percolation rate of each test in minutes per inch.(vii) The date of the test.(viii) Any other pertinent information.(d) Each percolation test shall be conducted at the owner's expense and in accordance with the following:(i) A percolation test may not be conducted in any test hole that extends into ground water, bedrock, or frozen ground. Where shrink-swell clays, fissured soil formations, or saprolite is encountered, each test shall be made under the direction of the regulatory authority.(ii) Since the appropriate percolation test depth depends on the soil conditions at a specific site, the percolation test shall be conducted only after the soil exploration pit has been dug and examined for suitable and porous strata and ground water table information. Percolation test results should be related to the soil conditions found.(iii) Each percolation test hole should begin in a specially prepared larger excavation, preferably made with a backhoe, of sufficient size that extend to a depth about 6 inches above the strata to be tested.(iv) Each test hole shall be dug or bored, preferably with hand tools such as shovels or augers, and shall have horizontal dimensions ranging from 4 to 18 inches, preferably 8 to 12 inches. The vertical sides shall be at least 12 inches deep, terminating in the soil at an elevation 6 inches below the bottom of the proposed onsite wastewater system. In testing individual soil strata for deep wall trenches and seepage pits, the percolation test hole shall be located entirely within the strata to be tested, if possible.(v) Each percolation test hole shall be properly prepared. Carefully remove any smeared soil surfaces to provide an open, natural soil interface into that water may percolate. Remove all loose soil from the bottom of the hole. Add 2 to 3 inches of clean pea gravel to protect the bottom from scouring or sealing with sediment when water is added. Caving or sloughing in some test holes can be prevented by placing in the test hole a wire cylinder or perforated pipe surrounded by clean pea gravel.(vi) Adequate saturation and swelling of the soil shall be completed. It is important to distinguish between saturation and swelling. Saturation means that the void spaces between soil particles are full of water. This can be accomplished in a relatively short period. Swelling is a soil volume increase caused by intrusion of water into the individual soil particles. This is a slow process, especially in clay-type soil, and is the reason for requiring a prolonged swelling period.(vii) Water should be placed carefully into the test hole using a small diameter siphon hose or other suitable method to prevent washing down the side of the hole.(viii) Necessary equipment for measuring the percolation rate should consist of a tape measure with at least 1/16 inch calibration or float gauge, and a time piece or other suitable equipment. All measurements shall be made from a fixed reference point near the top of the test hole to the surface of the water.(ix) Each percolation test shall follow a consistent procedure. The hole shall be carefully filled with clear water and a minimum depth of 12 inches shall be maintained above the gravel for at least a four hour period by refilling when necessary. Water remaining in the hole after four hours may not be removed. Immediately following the saturation period, the soil shall be allowed to swell not less than 16 hours or more than 30 hours. Immediately following the soil swelling period, the percolation rate measurements shall be made as follows:(A) Any soil that has sloughed into the hole shall be removed and water shall be adjusted to 6 inches over the gravel.(B) Thereupon, from the fixed reference point, the water level shall be measured and recorded at about 30 minute intervals for a period of four hours. (I) If 6 inches of water seeps away in less than 30 minutes, a shorter time interval of 15 minutes between measurements may be used.(II) If 6 inches of water seeps away in less than 15 minutes, a shorter time interval of 5 minutes between measurements may be used.(III) Eight consecutive time intervals shall be recorded unless two successive water level drops do not vary more than 1/16 of an inch and show that an approximate stabilized rate has been obtained.(C) The hole shall be filled with 6 inches of clear water above the gravel after each time interval.(D) In no case may the water depth exceed 6 inches above the gravel.(E) The final water level drop shall be used to calculate the percolation rate. If no stabilized rate is achieved, the smallest drop shall be used to make this calculation.(F) Precautions shall be taken to prohibit water or soil from freezing during the test procedure.(x) The percolation test procedure for Type 1 or Type 2 soils shall follow a separate procedure. The hole shall be carefully filled with clear water to a minimum depth of 12 inches over the gravel and the time for this amount of water to seep away shall be determined. The procedure shall be repeated and if the water from the second filling of the hole at least 12 inches above the gravel seeps away in 10 minutes or less, the test may proceed immediately as follows:(A) Water shall be added to a point not more than 6 inches above the gravel.(B) Thereupon, from the fixed reference point, water levels shall be measured at 10 minute intervals for a period of one hour. (I) If 6 inches of water seeps away in less than 10 minutes, a shorter time interval of 5 minutes between measurements may be used.(II) Six consecutive time intervals shall be recorded unless two successive water level drops do not vary more than 1/16 of an inch and show that an approximate stabilized rate has been obtained.(C) The hole shall be filled with 6 inches of clear water above the gravel after each time interval.(D) In no case shall the water depth exceed 6 inches above the gravel.(E) The final water level drop shall be used to calculate the percolation rate. If no stabilized rate is achieved, the smallest drop shall be used to make this calculation.(xi) The percolation rate is equal to the time elapsed in minutes for the water column to drop, divided by the distance the water dropped in inches and fractions thereof.(xii) The minimum or slowest percolation rate shall be used in calculating the required absorption area.(5) Appendix E. Septic Tank Operation and Maintenance. (a) Each septic tank shall be emptied before too much sludge or scum is allowed to accumulate and seriously reduce the tank volume settling depth. If either the settled solids or floating scum layer accumulate too close to the bottom of the outlet baffle or bottom of the sanitary tee pipe in the tank, solid particles may overflow into the absorption system and eventually clog the soil and ruin its absorption capacity.(b) A septic tank that receives normal loading should be inspected as stated in Section R317-4-11 to determine if it needs emptying. Although there are wide differences in the rate that sludge and scum accumulate in tanks, a septic tank for a private residence requires emptying every three to five years. Actual measurement of scum and sludge accumulation is the only sure way to determine when a tank needs to be emptied. Experience for a particular system may show the desirability of longer or shorter intervals between inspections.(c) The tank should be completely emptied if either the bottom of the floating scum mat is within 3 inches of the bottom of the outlet baffle or tee or the sludge level has built up to about 12 inches from the bottom of the outlet baffle or tee, or the scum and sludge layers together equal 40% or more of the tank volume. All scum and solids should be washed out and removed from the tank.(d) If multiple tanks or tanks with multiple compartments are provided, care should be taken to ensure that each tank or compartment is inspected and emptied.(e) Septic tank wastes contain disease causing organisms and shall be disposed of only in areas and in a manner that is acceptable to local health authorities and consistent with state rules.(f) Immediate replacement of any damaged inlet or outlet fitting in the septic tank is essential for effective operation of the system.(g) Remove any effluent screen or filter in a manner that prevents solids from passing to the absorption system. Wash the filter over the inlet side of septic tank. Replace the cleaned filter back into the outlet tee.(h) When the tank is empty, the interior surfaces of the tank should be inspected for leaks or cracks using a strong light.(i) A written record of any maintenance of the septic tank and absorption system should be kept by the owner of that system.(j) The functional operation of a septic tank is not improved by the addition of yeasts, disinfectants, additives or other chemicals; therefore, use of these materials is not recommended.(k) The advice of the regulatory authority should be sought before chemicals arising from a hobby or home industry or other unusual activities are discharged into a septic tank system.(l) Economy in the use of water helps prevent overloading of a septic tank system that could shorten its life and require expensive repairs. The plumbing fixtures in the building should be checked regularly to repair any leaks that can add substantial amounts of water to the system. Industrial wastes and other liquids that may adversely affect the operation of the onsite wastewater system should not be discharged into such a system. Paper towels, facial tissue, disinfectant wipes, newspaper, wrapping paper, disposable diapers, sanitary napkins, coffee grounds, rags, sticks, and similar materials should also be excluded from the septic tank since they do not readily decompose and can lead to clogging of both the plumbing and the absorption system.(m) Any measurable amount of sludge or scum present in any other tank should be removed. If an effluent screen or filter is present, it should be cleaned over the inlet side of the septic tank.Utah Admin. Code R317-4-14
Amended by Utah State Bulletin Number 2016-1, effective 1/1/2016Amended by Utah State Bulletin Number 2023-14, effective 6/29/2023