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7080.2450 MAINTENANCE.

Subpart 1.


All ISTS must be operated under the regulatory requirements of part 7082.0600. ISTS and all components must be maintained in compliance with this chapter and manufacturer requirements. Subpart 2, items A and B, are intended to apply to ISTS and systems that do not qualify as an ISTS, but receives sewage such as cesspools, drywells, leaching pits, or other pits.

Subp. 2.

Frequency of assessment.

The owner of an ISTS or the owner's agent shall regularly, but in no case less frequently than every three years:


assess whether sewage tanks leak below the designed operating depth and whether sewage tank tops, riser joints, and riser connections leak through visual evidence of major defects; and


measure or remove the accumulations of scum, grease, and other floating materials at the top of each septic tank and compartment, along with the sludge, which consists of the solids denser than water.

Subp. 3.

Removal of material.


All solids and liquids must be removed by pumping from all tanks or compartments in which the top of the sludge layer is less than 12 inches from the bottom of the outlet baffle or transfer hole or whenever the bottom of the scum layer is less than three inches above the bottom of the outlet baffle or transfer hole. Total sludge and scum volume must not be greater than 25 percent of the tank's liquid capacity.


Removal of accumulated sludge, scum, and liquids from septic tanks and pump tanks must be through the maintenance hole. The removal of solids from any location other than the maintenance hole is not a compliant method of solids removal from a sewage tank, and this method does not fulfill the solids removal requirement of this part or a management plan. Liquid and solids removal from clean-out pipes is allowed for holding tanks.


After removal of solids and liquids from a system installed after the adoption of a local ordinance adopted after February 4, 2008, the maintenance hole cover must be secured as described in part 7080.1970, item D. Covers secured by screws must be refastened in all screw openings.


After removal of solids and liquids from a system installed before the adoption of a local ordinance adopted after February 4, 2008, maintenance hole covers must be sound, durable, and of adequate strength as specified in part 7080.1970, item D, subitem (3), and:


be buried with a minimum of 12 inches of soil cover or, if the cover is currently at or above the ground surface or within 12 inches from final grade, be secured by a method that was deemed secure by the local ordinance that was in effect before February 4, 2008; or


meet the requirements of part 7080.1970, item D, if the cover is to be raised to be at or above the ground surface or within 12 inches from final grade.


Pump tanks must be maintained according to this part. Sludge must be removed if within one inch of the pump intake.

Subp. 4.

Toilet waste treatment devices and privies.


For primitive dwellings using toilet waste treatment devices in low dwelling density areas, septage disposal from these devices by the owner must be in accordance with local ordinances. If no ordinance exists, the septage must not be discharged to surface waters, drainageways, steeply sloping areas, or wet areas in a manner or volume that is harmful to the environment or public health or that creates a nuisance. The material must be buried or covered with soil. For site conditions not met in this subpart, the solids disposal from toilet waste treatment devices shall be according to subpart 6 by a licensed maintenance business.


When the privy is filled to one-half of its capacity, the solids must be removed. Abandoned pits must have the sewage solids and contaminated soil removed and must be filled with clean earth and slightly mounded to allow for settling. Removed solids shall be disposed of according to subpart 6.

Subp. 5.


ISTS additives, which are products added to the sewage or to the system with the intent to lower the accumulated solids in sewage, must not be used as a means to reduce the frequency of proper maintenance and removal of sewage solids from the sewage tanks as specified in this part. The use of additives does not fulfill the solids removal requirement of this part or a management plan. ISTS additives that contain hazardous materials must not be used in an ISTS.

Subp. 6.

Septage disposal.

Septage or any waste mixed with septage must be disposed of in accordance with state, federal, and local requirements for septage and other wastes. If septage is disposed of into a sewage or septage treatment facility, a written agreement must be provided between the accepting facility and the maintenance business.

Subp. 7.

Use of soil treatment site.

Activities on the current soil dispersal and treatment system or the reserve soil dispersal and treatment area as specified in part 7082.0100, subpart 3, item F, that impair the current or future treatment abilities or hydraulic performance of the soil treatment and dispersal system are prohibited. This includes, but is not limited to, covering all or part of the soil treatment system with an impermeable surface as determined by the local unit of government.

Subp. 8.

System remediation.

Any maintenance activity used to increase the acceptance of effluent to a soil treatment and dispersal system must:


not be used on a system failing to protect groundwater as defined in part 7080.1500, subpart 4, item B, unless the activities meet the requirements of parts 7080.2350 and 7080.2400;


not cause preferential flow from the soil treatment and dispersal system bottom to the periodically saturated soil or bedrock; and


be conducted by an appropriately certified qualified employee or an appropriately licensed business as specified in part 7083.0790.

Any substance added with the intent to increase the infiltration rate of the soil treatment and dispersal system must not contain hazardous substances.

Statutory Authority:

MS s 115.03; 115.55


32 SR 1347; 35 SR 1353; 38 SR 1001

Published Electronically:

January 22, 2014

Official Publication of the State of Minnesota
Revisor of Statutes