Final treatment and dispersal must be according to applicable design requirements in chapter 7080, except as modified in this part. Code of Federal Regulations, title 40, parts 144 and 146, prescribe additional design regulations applicable to certain systems designed under this chapter. At a minimum, flow amounts to be used for the purposes of this part must be derived from part 7081.0110.
MSTS components must meet the setbacks in Table II.
|Minimum Setback Distances (feet)|
or Sealed Privy
|Water supply wells||*||*||*|
|Buried water lines||*||*||*|
|System site boundaries||10||10|
|The ordinary high water level of public waters||***||***|
*Setbacks from buried water pipes and water supply wells are governed by chapters 4714 and 4725, respectively.
**If setbacks are reduced through local administrative processes, the system shall not be located under or within the structure.
***Setbacks from lakes, rivers, and streams are governed by chapters 6105 and 6120.
The site proposed to support the soil treatment and dispersal system must:
have the upper 12 inches of the absorption area:
be original soil;
have a soil loading rate of greater than zero as listed in Table IX or IXa, in part 7080.2150, subpart 3, item E; and
be above the periodically saturated soil or bedrock;
meet the area size requirements in subpart 5 and setbacks in subpart 2 and all easements;
not be a wetland or floodway;
not be in an area in which surface runoff from precipitation will concentrate (concave hillslope); and
allow the system to be placed on contour.
Inspection pipes must be located to adequately assess the hydraulic performance of the entire soil dispersal system.
Effluent loading rates to the soil must be determined in:
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 subpart 7, for proper hydraulic functioning, and for concentration reduction of nitrogen and phosphorus, if applicable.
Additional set-aside land area of 100 percent of the size determined in subpart 6 is required for systems whose absorption area receives effluent meeting treatment level A or B in part 7083.4030 or designed in accordance with part 7080.2400. Additional land area of 50 percent of the size determined in subpart 6 is required for systems whose absorption area receives treatment level C in part 7083.4030. The reserve land area must be identified and protected for future use if necessary. Replacement MSTS proposed on sites that cannot meet this requirement are allowed to be exempted by the local unit of government.
For treatment of effluent by soil to meet the performance criteria in part 7081.0080, subpart 4, item C, the soil treatment and dispersal systems must meet the requirements of item A, B, or C.
For soil treatment and dispersal systems that receive treatment level A-2, B-2, or C effluent as described in part 7083.4030, the soil treatment zone requirements must meet part 7080.2150, subpart 3, item C. The required three-foot vertical separation must be maintained during operation after accounting for groundwater mounding.
For soil treatment and dispersal systems that receive treatment level A or B effluent as described in part 7083.4030, the soil treatment zone requirements must meet part 7080.2150, subpart 3, item C, unless it is modified in Table XI of part 7080.2350, subpart 2, with a minimum vertical separation of two feet. The required vertical separation must be maintained during operation after accounting for groundwater mounding.
An observation well to measure the height of the periodically saturated soil beneath the operating system must be installed and monitored according to the operating permit.
Phosphorus mitigation methods must be employed to achieve compliance with part 7081.0080, subpart 4, item E, if natural processes are found inadequate.
All information required in this part shall be submitted for review and approval by the local unit of government prior to system construction, including all applicable information delineated on a map.
32 SR 1400; 35 SR 1353; 38 SR 1001; 40 SR 689
October 31, 2016
Official Publication of the State of Minnesota
Revisor of Statutes