§ 52.20 TYPE IV SYSTEMS.

   (A)   A system designed according to this part is considered a Type IV System. The system must:

      (1)   Employ design flow values in § 52.12.

      (2)   Meet or exceed applicable technical requirements of §§ 52.13, 52.14, and 52.15.

      (3)   Meet or exceed the requirements of § 52.16(B).

      (4)   Meet or exceed the requirements of § 52.16(C)(A) and (B).

      (5)   Meet or exceed the requirements of Table IX, and Table XII in Minn. Rule 7080.23504 or Table X.

   (B)   Type IV systems can be used on previously developed Sites only when a Type I or Type II system cannot be installed or is not the most suitable treatment.

   (C)   Type IV systems will not be allowed in areas where a new system or modifications to a new system are not feasible if failure occurs.

   (D)   Type IV systems will be allowed for undeveloped Lots only when two Type I or Type II soil treatment and dispersal areas have been identified on the Lot, in addition to the area utilized by the Type III soil treatment and dispersal area. The Lot must be able to accommodate Long-Term Sewage Treatment in addition to the area utilized by the Type IV system.

Table IX

Treatment Component Performance Levels and Method of Distribution by Texture Group1.

 

Vertical Separation (inches)	Soil Texture Croup Found in Table IX in Minnesota Rules, Chapter 7080.21501
	1-5	6-9	10-11
12 - 17	Treatment Level A, Pressure Distribution, Timed Dosing
18 - 23	Treatment Level B, Pressure Distribution, Timed Dosing		Treatment Level B, Pressure Distribution
24 - 36	Treatment Level B, Pressure Distribution, Timed Dosing	Treatment Level B, Pressure Distribution

 

1 The treatment component performance levels correspond with those established for treatment components under the product testing requirements in Table III of Minn. Rule 7083.4030.

   (E)   A Type IV system's Absorption Area must be sized according to Table XII-Loading Rates for Determining Bottom Absorption Area for Trenches and Seepage Beds for Effluent Meeting Treatment Level A and B and Absorption Ratios for Determining Mound Absorption Areas Using Detailed Soil Descriptions, as found in Minn. Rules 7080.23504 or by using Table X if not using detailed soil descriptions.

Table X

LOADING RATES FOR DETERMINING BOTTOM ABSORPTION AREA FOR TRENCHES AND SEEPAGE BEDS FOR EFFLUENT MEETING TREATMENT LEVELS A AND B AND ABSORPTION RATIOS FOR DETERMINING MOUND ABSORPTION AREAS USING PERCOLATION TESTS.

Percolation Rate (Minutes Per Inch)	Soil Loading Rate (gdp/ft2)	Mound Absorption Ratio
< 0.1*	-	-
0.1 - 5*	1.60	1
0.1 - 5 (Soil Texture Group 3)	1.0	2
6 - 15	1.0	1.3
16 - 30	0.78	2
31 - 45	0.78	2.4
46 - 60	0.6	2.6
> 60	0.3	5.0