2019.02.04 CC Packet - Laserfiche WebLink

Home

Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations Sieve Size Percent Passing No.4 95-100 No.8 80-100 No.10 0-100 No.40 0-100 No.60 0-40 No.200 0-5 Clean sand must also contain less than three percent deleterious substances and be free of organic impurities. (D) The original soil mound absorption area is determined by multiplying the original soil mound absorption length by the original soil mound absorption width. The original soil absorption width is calculated by multiplying the mound distribution media bed width by the mound absorption ratio. The mound absorption ratio of the upper 18 inches of soil for new construction, or 12 inches of soil for previously developed sites, in the proposed original soil mound absorption area shall be determined according to Table VI or Table VIa. (E) The required original soil absorption width for mounds constructed on slopes from zero to one percent must be centered under the mound distribution media bed width. The required original mound soil absorption width constructed on slopes greater than one percent must be measured downslope from the upslope edge of the mound distribution media bed width and measured in the direction of the original land slope and perpendicular to the original contours. (F) The side slopes on the mound must not be steeper than three horizontal units to one vertical unit and shall extend beyond the required absorption area, if necessary. (G) Distribution of effluent over the mound distribution media bed must be by level perforated pipe under pressure according to Section 14 and Section 15. (H) The supply pipe from the pump to the original soil absorption area must be installed before surface preparation of the original mound soil absorption area. The trench excavated for the supply pipe must be carefully backfilled and compacted to prevent seepage of effluent. (1) Vegetation in excess of two inches in length and dead organic debris including leaf mats must be removed from the original soil mound absorption area. Trees must be cut nearly flush with the ground and stumps must not be removed. (J) The original soil mound absorption area must be roughened by backhoe teeth, moldboard, or chisel plow. The soil must be roughened to a depth of eight inches. Discing is allowed if the upper eight inches of soil has a texture of sandy loam or coarser. If plowed, fixrrows must be thrown uphill and there must not be a dead furrow in the original soil mound absorption area. A rubber tired tractor is allowed for plowing or discing. Rototilling or pulverizing the soil is not allowed. The original soil must not be excavated or moved more than one foot from its original location during soil surface preparation. (K) All surface preparation must take place when the upper 12 inches of soil has a moisture content of less than the plastic limit and soil conditions allow field testing of soil properties and these properties are maintained throughout the installation. (L) Prior to placement of six inches of clean sand, vehicles must not be driven on the original soil mound absorption area before or after the surface preparation is completed. The clean sand must immediately be placed on the prepared surface. (M) If rainfall occurs on the prepared surface, the site must be allowed to dry below the plastic limit and roughened as described in Section 17.3 (3)(J). (N) The clean sand must be placed by using a construction technique that minimizes compaction. If the clean sand is driven on for construction, a crawler or track -type tractor 69 Washington County Development Code