(A) A system designed according to this part is considered a Type III system. A system in soils with a loading rate of less than 0.45 gallons per day per square foot may be installed on previously developed Sites as a Type III system. The system must:
(1) Employ design flow values in § 52.12.
(2) Meet or exceed technical requirements in § 52.14(G)(1).
(3) Meet or exceed the requirements of § 52.16(B).
(4) Meet or exceed the requirements of § 52.16(C)(1), (2), (3), (7), (8), and (9).
(5) For previously developed Sites, if the Site cannot accommodate a soil treatment and dispersal system sized in accordance with Table IX in Minn. Rule 7080.21501 or Table VI, a smaller soil treatment and dispersal system is allowed to be constructed if it employs flow restriction devices that do not allow loadings in excess of those in Table IX in Minn. Rule 7080.21501 or Table VI.
(B) Absorption areas sized smaller than a Type I system must employ flow restriction devices that do not allow Absorption Area loadings in excess of those in Table IX in Minn. Rule 7080.21501 or Table VI. This provision does not apply to the Original Soil, Clean Sand Absorption Area of a Mound System.
(C) Type III 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.
(D) Type III systems will not be allowed in areas where a new system or modifications to a new system are not feasible if failure occurs.
(E) Type III 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 III system.
(F) Graywater systems.
(1) Graywater Systems shall be classified as a Type III system and must meet or exceed the following requirements:
(a) Employ 60% of the flow values in § 52.12.
(c) Meet or exceed the requirements of § 52.17.
(d) Meet or exceed the requirements of § 52.16(B) and (C).
(e) Meet the requirements of divisions (F)(2) and (3) of this section.
(2) Toilet waste must not be discharged to a Graywater system.
(3) The Liquid Capacity of a Graywater Septic Tank serving a Dwelling must be based on the number of Bedrooms existing and anticipated in the Dwelling served and shall be at least as large as the capacities given in Table VIII.
Table VIII - Minimum Septic Tank Capacity for Graywater Systems
Number of Bedrooms | Tank I | Tank 2 |
Two or less | 1,000 | 500 |
Three | 1,000 | 500 |
Four to Five | 1,000 | 1,000 |
Six to Seven | 1,000 | 1,000 |
Eight to Nine | 1,500 | 1,000 |
Ten or More | Septic tank shall be sized as: (2,000 + ((# of Bedrooms -9)*150)). | |