R317-4-14. Appendices

  Appendix A. Septic Tank Construction.

  1.1. Plans for Tanks Required.

  Plans for all septic tanks and underground holding tanks 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. All tanks shall conform to the design drawing and shall be constructed under strict, controlled supervision by the manufacturer.

  A. Precast Reinforced Concrete Tanks.

  1. The walls and base of precast tanks shall be securely bonded together and the walls shall be of monolithic or keyed construction.

  2. The sidewalls and bottom of such tanks shall be at least 3 inches in thickness.

  3. The top shall have a minimum thickness of 4 inches.

  4. Such tanks 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.

  5. All concrete used in precast 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 assure water tightness.

  6. 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.

  7. Excessively mortared joints should be trimmed flush.

  8. The inside and outside of each mortar joint shall be sealed with a waterproof bituminous sealing compound.

  9. For the purpose of early reuse of forms, the concrete may be steam cured. Other curing by means of 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.

  B. Poured-In-Place Concrete Septic Tanks.

  1. The top of poured-in-place septic tanks 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.

  2. The top of tanks 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.

  3. 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.

  4. A 6 inch water stop shall be used at the wall-floor juncture to ensure water tightness.

  5. 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.

  6. Curing of concrete shall comply with the requirements in Subsection R317-4-14 Appendix A.1.2.

  C. Fiberglass Tanks.

  1. Fiberglass tanks shall comply with one of the following criteria for acceptance.

  a. 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.

  b. Manufactured to meet the structural requirements of Underwriters Laboratories (UL) Standard 1316.

  c. Professionally engineered plans demonstrating compliance to tank configuration requirements of this rule including acceptable structural calculations or other pertinent data as may be required.

  2. Inlet and outlet tees 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.

  3. The tank shall be installed in accordance with the manufacturer's recommendations.

  D. Polyethylene Tanks.

  1. Polyethylene tanks shall comply with the criteria for acceptance established in Prefabricated Septic Tanks and Wastewater Holding Tanks, Can3-B66-10 by the Canadian Standards Association, Ontario, Canada.

  2. Inlet and outlet tees 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.

  3. The tank shall be installed in accordance with the manufacturer's recommendations.

  1.2. Identifying Marks.

  A. All prefabricated or precast tanks that are commercially manufactured shall be plainly, legibly, and permanently marked or stamped with:

  1. the manufacturer's name and address, or nationally registered trademark;

  2. 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

  3. the inlet and outlet of all such tanks shall be plainly marked as "IN" or "OUT" respectively.

  1.3. Inlets and Outlets.

  Inlets and outlets of tanks or compartments thereof shall meet the minimum diameter requirements for building sewers.

  A. Only one inlet or outlet is allowed, unless preauthorized by the regulatory authority.

  B. Inlets and outlets shall be located on opposite ends of the tank.

  1. 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.

  2. Approved tanks with offset inlets may be used when approved by the regulatory authority.

  C. All inlets and outlets shall have a baffle or sanitary tee.

  1. 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.

  2. For tanks with vertical sides, outlet baffles or sanitary tees shall extend below the liquid surface a distance equal to approximately 40% of the liquid depth. For horizontal cylindrical tanks and tanks of other shapes, that distance shall be reduced to approximately 35% of the liquid depth.

  3. All baffles shall be constructed from sidewall to sidewall or shall be designed as a conduit.

  4. All sanitary tees shall be permanently fastened in a vertical, rigid position.

  D. Inlet and outlet pipe connections to the septic tank shall be sealed and adhere to the tank and pipes to form watertight connections with a bonding compound or sealing rings.

  E. Inlet and outlet devices may not include any design features 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 the baffles or sanitary tees shall extend at least 6 inches above the liquid level in order to provide scum storage, but no closer than 1 inch to the inside top of the tank.

  1.4. Liquid Depth of Tanks.

  Liquid depth of tanks shall be at least 30 inches. Depth in excess of 72 inches may only be considered in calculating liquid volume required in Subsection R317-4-6.6 if the tank length is at least two times the liquid depth.

  1.5. Burial Depth.

  The maximum burial depth shall be stated on the plans submitted.

  1.6. Tank Compartments.

  Septic tanks may be divided into compartments provided they meet the following:

  A. The volume of the first compartment shall equal or exceed two-thirds of the total required septic tank volume;

  B. No compartment shall have an inside horizontal dimension less than 24 inches;

  C. Inlets and outlets 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 approximately equal to 40% of the liquid depth of the tank.

  1.7. Scum Storage.

  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.

  1.8. Access to Tank Interior.

  Adequate access to the 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:

  A. Access to each compartment of the tank shall be provided through properly placed manhole openings not less than 18 inches in diameter, in minimum horizontal dimension or by means of an easily removable lid section.

  B. All access covers shall be designed and constructed in such a manner that they cannot pass through the access openings, and when closed will be child-proof and prevent entrance of surface water, dirt, or other foreign material, and seal the odorous gases in the tank. Concrete access covers for manhole openings shall have adequate handles.

  C. Access to inlet and outlet devices shall be provided through properly spaced openings not less than 12 inches in minimum horizontal dimension or by means of an easily removable lid section.

  Appendix B. Pressure Distribution, Pumps, Controls, and Alarms.

  1.1. Design.

  The 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. Electrical components used in onsite wastewater systems shall comply with applicable requirements of the State of Utah Electrical Code.

  C. All components shall be constructed and installed to facilitate ease of service without having to alter any other part.

  1.2. Pumps, Controls, and Alarms.

  Prior to final approval for operation, all pumps, controls and related apparatus shall be field tested and found to operate as designed.

  A. When duplex pump system is designed, controls shall be provided that an alarm will 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.

  1. The control panel for all pressure distribution systems shall include a pump run-time hour meter and a pump event counter or other acceptable flow measurement method.

  2. The control panel shall be installed within sight of the access risers.

  a. Other locations may be approved by the regulatory authority.

  3. Supporting hydraulic calculations and pump curve analysis shall be submitted to the regulatory authority with the design.

  Appendix C. Soil Exploration Pits, Soil Logs, Soil Evaluations.

  1.1. Soil Exploration Pit Construction.

  Soil conditions shall be obtained from soil exploration pit(s) 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. In the event that absorption system excavations will be deeper than 6 feet, soil exploration pits shall extend to a depth of at least 4 feet below the bottom of the proposed absorption system excavation.

  A. Soil exploration pits 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.

  1.2. Soil Logs.

  A. The soil log shall contain the following information.

  1. A signed statement certifying that the logs were evaluated and recorded in accordance with this rule.

  2. The names of all qualified individuals per Rule R317-11 conducting the tests.

  3. The location of the property.

  4. The location of the soil exploration pit on the property.

  5. The date of the log.

  6. 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. other pertinent information.

  1.3. Soil Evaluation.

  Soils shall be evaluated using the USDA Soil Texture Classification method.

  A. The soil horizon with the lowest loading rate shall be used in calculating the required absorption area.

  Appendix D. Percolation Method.

  1.1. Percolation Test Requirements.

  Percolation tests shall be completed by an individual certified per Rule R317-11 and shall be conducted in accordance with the instructions in this appendix.

  A. Typical Areas.

  When percolation tests are conducted, such tests shall be conducted at points and elevations selected as typical of the area in which the absorption system will be located.

  B. Percolation Test Certificate.

  Percolation test results shall be submitted on a signed "Percolation Test Certificate". The test certificate shall contain the following:

  1. A signed statement certifying that the tests were conducted in accordance with this rule.

  2. The names of all individuals per Rule R317-11 conducting the tests.

  3. The location of the property.

  4. The location of the percolation tests on the property.

  5. The depth to the bottom of the percolation test hole from the existing grade.

  6. The final stabilized percolation rate of each test in minutes per inch.

  7. The date of the tests.

  8. Other pertinent information.

  C. Specific Requirements.

  Percolation tests shall be conducted at the owner's expense and in accordance with the following:

  1. Conditions Prohibited for Test Holes.

  Percolation tests may not be conducted in test holes that extend into ground water, bedrock, or frozen ground. Where shrink-swell clays, fissured soil formations, or saprolite is encountered, tests shall be made under the direction of the regulatory authority.

  2. Soil Exploration Pit Prerequisite to Percolation Tests.

  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.

  3. Test Holes to Commence in Specially Prepared Excavations.

  All percolation test holes should commence in specially prepared larger excavations, preferably made with a backhoe, of sufficient size that extend to a depth approximately 6 inches above the strata to be tested.

  4. Type, Depth, and Dimensions of Test Holes.

  Test holes shall be dug or bored, preferably with hand tools such as shovels or augers, etc., 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.

  5. Preparation of Percolation Test Hole.

  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.

  6. Saturation and Swelling of the Soil.

  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 of time. 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.

  7. Placing Water in Test Holes.

  Water should be placed carefully into the test holes by means of a small diameter siphon hose or other suitable method to prevent washing down the side of the hole.

  8. Percolation Rate Measurement, General.

  Necessary equipment 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.

  9. Percolation Test 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 whenever 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 approximately 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 indicate 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.

  i. 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.

  10. Test Procedure for Type 1 and Type 2 Soils.

  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 indicate 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.

  i. If no stabilized rate is achieved, the smallest drop shall be used to make this calculation.

  11. Calculation of Percolation Rate.

  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.

  12. Using Percolation Rate to Determine Absorption Area.

  The minimum or slowest percolation rate shall be used in calculating the required absorption area.

  Appendix E. Tank Operation and Maintenance.

  1.1. Maintenance of Septic Tanks.

  A. Septic tanks 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 will 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 indicated 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 will generally require 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 indicate 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 approximately 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 damaged inlet or outlet fittings in the septic tank is essential for effective operation of the system.

  G. Effluent screens or filters.

  Remove the 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 all maintenance of the septic tank and absorption system should be kept by the owner of that system.

  J. The functional operation of septic tanks 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 your 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 necessitate 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.

  1.2. Maintenance of Other Tanks.

  A. Other Tanks.

  Any measurable amount of sludge or scum present in other tanks should be removed.

  B. If a screen is present, it should be rinsed and cleaned over the opening of the septic tank.