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Effective April 28, 2015 Chapter Four Subsurface Sewage Treatment System Regulations <br />SECTION 20 TYPE IV SYSTEMS <br />20.1 General. <br />A system designed according to this part is considered a Type IV System. This system must: <br />(1) Employ design flow values set forth in Section 12. <br />(2) Meet or exceed applicable technical requirements of Section 13, Section 14, and Section 15. <br />(3) Meet or exceed the requirements of Section 16.2. <br />(4) Meet or exceed the requirements of Section 16.3except as modified in this part. <br />(5) Meet or exceed the requirements of Table IX. <br />(6) Meet soil dispersal requirements of Section 17, except that the reductions in Section 17.2(3)(D)) are <br />not applicable. <br />20.2 Previously Developed Sites. <br />Type IV systems may be used on previously developed sites only when a Type I or Type II system cannot be <br />installed or is not the most suitable treatment. <br />20.3 Type IV Systems Allowed. <br />Type IV systems will be allowed for undeveloped lots only when two Type I or Type II soil treatment and dispersal <br />areas have been identified on the lot, in addition to the area utilized by the Type IV soil treatment and dispersal <br />area. The lot must be able to accommodate long-term sewage treatment in addition to the area utilized by the Type <br />IV system. <br />Table IX <br />TREATMENT COMPONENT PERFORMANCE LEVELS AND METHOD OF DISTRIBUTION BY <br />TEXTURE GROUP'. <br />Texture Grou 2 <br />All Sands and <br />Sandy Loam, <br />Clay, Clay Loam <br />Vertical <br />Separation (inches) <br />Loamy Sands <br />Loam, Silt <br />Loam <br />12 — 173 <br />Treatment Level A, Uniform Distribution, Timed Dosing <br />3 <br />Treatment Level B Uniform <br />Treatment Level B, <br />18 - 35 <br />Distribution, Timed Dosing <br />Uniform <br />Distribution <br />Treatment Level <br />—36+3 <br />A-2 or B-2 <br />Uniform , <br />Treatment Level A-2 or B-2, Uniform <br />Distribution, <br />Distribution, Treatment Level C <br />Treatment Level C <br />' The treatment component performance levels correspond with those established for treatment components <br />under the product testing requirements in Table III of Minnesota Rules, 7083.4030. <br />2 With less than 50 percent rock fragments. <br />3 Additional vertical separation distance is required as determined in Section 16.3(3). <br />20.4 Soil Loading Rates. <br />The absorption area and mound absorption ratio must be sized according to Table VI or Table VIa. <br />78 Washington County Development Code <br />