2019.02.04 CC Packet - Laserfiche WebLink

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Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations (4) Sewage tanks must not be placed in floodways, drainage ways, or swales. Upslope drainage must be diverted away from the location of all tanks. A tank's final cover must be crowned or sloped to shed surface water. (5) Sewage tanks must not be placed in areas subject to vehicular traffic unless engineered for the anticipated load. (6) Sewage tanks must be placed on firm and evenly compacted soil and with the soil level in all directions. The bottom shall be excavated in a manner so the vertical load is borne by the tank walls and not the tank bottom. If the bottom of the tank excavation contains rocks, bedding material must be used according to manufacturer's instructions. The soil beneath the tank must be capable of bearing the weight of the tank and its contents. (7) Sewage tanks and risers must be installed according to manufacturer's requirements and in a structurally sound and watertight fashion. (8) If the top of a sewage tank is to be less than two feet from final grade, the lid of the tank must be insulated to an R-value of ten. Maintenance hole covers must be insulated to an R-value of ten. All insulating materials must be resistant to water absorption. (9) Sewage tanks placed below the level of the periodically saturated soil must employ a method to protect against flotation under periodic saturated soil conditions when the tank is empty. (10) Connections between the concrete tank and the building sewer or supply pipe must meet the requirements of American Society for Testing and Materials, Standard Specification for Resilient Connectors Between Reinforced Concrete Manhole Structures, Pipes, and Laterals, ASTM C923 (2002), or equivalent. The standard is incorporated by reference, is available through the Minitex interlibrary loan system, and is not subject to frequent change. (11) Joints of concrete tanks, concrete tank lids, and concrete risers must be sealed using a bonding compound that meets American Society for Testing and Materials, Standard Specification for Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants, ASTM C990 (2003). The standard is incorporated by reference, is available through the Minitex interlibrary loan system, and is not subject to frequent change. 13.24 Tank Assessment (1) General (A) All sewage tanks must be watertight, including at all tank and riser joints, riser connections, and pipe connections. (B) An assessment of all models of sewage tanks to be used must be conducted to determine: i. the structural integrity of the tank design; and ii. the adequacy of the manufacturing process of watertightness. (C) Sewage tanks, including riser joints, riser connections, and pipe connections must be designed, manufactured, and installed to be watertight under normal use. (2) Structural Integrity of Design Test. The structural integrity of each model of tank and all poured - in -place tanks must be verified by calculation, proof testing, or a licensed professional engineer to determine the horizontal and vertical loads that the tank can withstand when empty. Tanks must be reverified for structural integrity if the design, materials, or construction methods are modified. A licensed professional engineer shall certify in writing if different manufactured models are similar enough so that the structural integrity information for one model is valid for other models. Verifications must be submitted to the commissioner. (3) Watertightness Test (A) At least one tank per year, per model must be tested for watertightness. All poured -in -place tanks shall be tested for watertightness. Records of testing must be maintained by the manufacturer for three years and must be available to the commissioner and local unit of government if requested. Tanks must be tested and meet or exceed the applicable requirements of subitems (i), (ii), or (iii): i. When empty, a tank must maintain a vacuum of at least two inches of mercury for five minutes, without loss of pressure; 52 Washington County Development Code