2019.02.04 CC Packet - Laserfiche WebLink

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Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations (C) The top and bottom of the distribution medium must be level along the contour. Sidewalls must be as vertical as practical and not intentionally sloped. (D) The minimum depth of soil cover, including topsoil borrow, over the distribution medium is 12 inches. (E) Trenches or seepage beds must be backfilled and crowned above finished grade to allow for settling. The top six inches of the backfill must have the same texture as the adjacent soil. (F) Trenches and seepage beds in which the distribution media is in contact with soils that are sand, loamy sand, fine sand, or loamy fine sand or soils with a percolation rate of 0.1 to 5 minutes per inch must employ one or more of the following measures: i. Employ pressure distribution according to Section 14.4; ii. Divide the total dispersal area into multiple units that employ serial distribution, with each dispersal unit having no greater than 15 percent of the required bottom absorption area; iii. Have a vertical separation distance of at least five feet. 17.3 Mounds (1) Mound System Requirements. To qualify as a mound system, the system must meet or exceed the following requirements: (A) Employ flow values in Section 12. (B) Meet or exceed applicable technical requirements of Section 13, Section 14, and Section 15. (C) Meet or exceed the requirements of Sections 16.2 and 16.3. (2) Location of Mounds (A) The upper 18 inches of the original soil mound absorption area must have a minimum loading rate of 0.45 gallons per day per square foot and a mound absorption ratio greater than zero, but no more than 2.6 in Table VI or Table VIa. The upper 18 inches of the absorption area must also be above the periodically saturated soil or bedrock. (B) For previously developed sites, the upper 12 inches of the original soil mound absorption area must have a mound absorption ratio of greater than zero in Table Vlor Table VIa. The upper 12 inches of the absorption area must also be above the periodically saturated soil or bedrock. (C) Setbacks must be according to Table V. Setbacks must be measured from the original soil absorption area. (D) On slopes of one percent or greater and where the original soil mound absorption ratio is 2.6 or greater in Table VI or Table VIa, mounds must not be located where the ground surface contour lines that lie directly below the long axis of the distribution media bed represent a swale or draw, unless the contour lines have a radius of curvature greater than 100 feet. Mounds must never be located in swales or draws where the radius of curvature of the contour lines is less than 50 feet. (E) In no case shall mounds be placed on slopes greater than 12 percent. (3) Mound Design and Construction (A) The mound distribution media bed area consists of bottom area only and must be calculated by dividing the design flow by 1.0 gallons per square foot per day. (B) Mound distribution media bed width is determined according to Section 16.3 (13) and must be no wider than ten feet. (C) Clean sand must be used to elevate the mound distribution media bed and must consist of sound, durable material that conforms to the following requirements: 68 Washington County Development Code