2019.02.04 CC Packet - Laserfiche WebLink

Home

Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations (11) Sewage tank effluent concentrations to the soil dispersal system must not exceed a BOD concentration of 170 mg/L, a CBOD5 concentration of 125mg/L, a TSS concentration of 60 mg/L, or an oil and grease concentration of 25 mg/L. (12) The distribution media must not be in contact with soils that have any sand soil texture containing 50 percent or more rock fragments or any soils that have a percolation rate of less than 0.1 minutes per inch. (13) The contour loading rate for soil dispersal systems must be between 1 and 12 gallons per lineal foot per day 16.4 Nitrogen BMP. At a minimum, systems designed under this Chapter with a design flow of greater than 2,500 gallons per day, which impact water quality of an aquifer, as defined in Minnesota Rules, Chapter 4725.0100, subpart 21, must employ best management practices for nitrogen reduction developed by the Commissioner to mitigate water quality impacts to groundwater. 16.5 Final treatment and dispersal for MSTS: (1) General. Final treatment and dispersal must be according to applicable design requirements of this Chapter, except as modified in this Section. Code of Federal Regulations, Title 40, Parts 144 and 146, prescribe additional design regulations applicable to certain systems. At a minimum, flow amounts to be used for the purpose of this Section must be derived from Table I or II in Section 12 of this Chapter. (2) Setbacks. MSTS must meet all setbacks in Table V. (3) Minimal Soil and Site Conditions. The site proposed to support the soil treatment and dispersal system must: (A) Have the upper 18 inches of the absorption area: i. Be original soil; ii. Have a soil loading rate of greater than zero as listed in Table VI or Table VIa, in Section 16.3; iii. Be above the periodically saturated soil or bedrock; (B) Not be a wetland or floodway; (C) Not be in an area in which surface runoff from precipitation will concentrate (concave hillslope); and (D) Allow the system to be placed on contour. (4) Inspection Pipes. Inspection pipes must be located to adequately assess the hydraulic performance of the entire soil dispersal system. (5) Soil Absorption Area Sizing (A) Effluent loading rates to the soil shall be no greater than loading rates prescribed in: i. Table VI, or Table VIa in Section 16.3, if the absorption area receives treatment level C effluent as described in Minnesota Rules 7083.4030. ii. Section 21. (6) If the absorption area receives effluent not as described in Section 16.5 (5)(A), the absorption area shall be increased by 50 percent of the amount derived in Table VI or VIa, and zoned for dosing and resting. (7) System Geometry, Lawn Area Sizing, and Groundwater Mounding. The system geometry and lawn area sizing shall be sized to prevent groundwater mounding from violating the unsaturated zone beneath the soil system according to Section 16.5 (9) for proper hydraulic functioning, and for concentration reduction of nitrogen and phosphorus, if applicable. (8) Reserve Land Area. Additional set -aside land area of 100 percent of the size determined in Section 16.5 (5) to 16.5(7) is required for systems whose absorption area receives effluent meeting treatment level A or B in part Minnesota Rules, 7083.4030 or designed in accordance with Section 21. Additional land area of 50 percent of the size determined in Section 16.5 (5) to 16.5(7) is 64 Washington County Development Code