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Minnesota Pollution <br />Control Agency <br />Subsurface Sewage Treatment <br />Systems and Building, Structures <br />and Lot Improvements <br />Setbacks and Other Restrictions <br />This factsheet is offered to assist Subsurface Sewage Treatment Systems (SSTS) designers and local units of government in <br />the sometimes difficult decision on the needed separation distance or other restrictions between Buildings, Structures or <br />other Lot Improvements (BSLI) and a SSTS. <br />Purpose of setbacks <br />The purpose of a setback to BSLI is as follows: <br />1. That construction of the SSTS does not damage the superstructure or in -ground structural integrity of an existing <br />BSLI. <br />2. That construction of the BSLI does not damage an existing SSTS or future area of a proposed soil dispersal system. <br />3. That the location, use or operation of the BSLI does not hinder the use, operation and maintenance of the SSTS. <br />4. That the location, use, operation or maintenance of the SSTS does not hinder the operation of the BSLI. <br />5. That personal and/or public health and safety is protected. <br />Setback requirements <br />If a BSLI is implicated in just one of the items in one through five above, it is considered a "structure" as defined in Minn. <br />R. 7080.1100, subp. 80(A). The distance between a "structure" and a SSTS is a minimum of 10 feet from sewage tanks and <br />a minimum of 20 feet from the absorption area of the soil dispersal system (Minn. R. 7080.2150, subp. 2(E) - Table VII). <br />In some instances, a BSLI which does not qualify as a "structure" may need to have some other requirement placed (i.e., <br />restriction) for justifiable reasons to accommodate unforeseen issues not covered under items one through five. <br />Mandatory situations <br />There are some situations in which there is very little discretion in determining the regulatory requirements between a SSTS <br />and a BSLI as described below: <br />1. In no instance should the soil dispersal unit be covered by an impermeable surface which cuts off oxygen into the <br />soil, even if aerobic effluent is being discharged. <br />2. Sewage tanks must not be place in areas receiving traffic from heavy equipment, unless the tank is designed for the <br />anticipated load. <br />3. No lot improvement shall damage or prohibit use of the secondary (back-up) soil dispersal site. <br />4. A setback is required from all occupied structures. <br />Types of lot improvements <br />There are many types of lot improvements which need to be considered when assessing if a suitable setback distance or <br />other restriction is imposed. A list of some common lot improvements are listed below: <br />• dwellings with basements <br />• dwellings with frost footings <br />• dwellings without a foundation (mobile homes) <br />• attached and unattached garages with frost footings <br />• unattached garages or buildings with slab -on -grade foundations <br />• attached and unattached decks with frost footings <br />wq-wwists4-47 August 2011 <br />Minnesota Pollution Control Agency • 520 Lafayette Rd. N., St. Paul, MN 55155-4194 • www.pca.state.mn.us <br />651-296-6300 • 800-657-3864 • TTY 651-282-5332 or 800-657-3864 • Available in alternative formats <br />