Planning - On-site Wastewater Treatment Systems

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An on-site wastewater treatment system consists of four major components: the building sewer (pipe exiting home), the septic tank, the drainfield (or absorption system) and the soil. The septic tank separates the solids from the liquids before the liquid (or effluent) enters the drainfield. The absorption system then disperses the effluent into the soils. Microorganisms in the soil provide further treatment by removing constituents such as nitrates, phosphates, bacteria and viruses.

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At a minimum, taking these four steps to maintain an on-site wastewater treatment system may prolong the life of the system:

  • Conserve water.
  • Flush responsibly.
  • Pump the septic tank.
  • Take care in what goes down the drain.
The solids from household wastes accumulate in the septic tank and are more commonly called "sludge". With continued use, this sludge volume continues to increase over time. If the sludge volume reaches the outlet tee, it begins to enter the drainfield. The sludge will eventually plug the outlet pipe of the septic tank and/or plug the drainfield soils, therefore, decreasing the soils’ infiltration ability. A soil’s infiltration ability is its ability to filter the effluent’s contaminants, such as nutrients and pathogens. Once the drainfield is plugged with solids, it loses its effectiveness in treating wastes, which include nutrients and pathogens. These untreated nutrients and pathogens can potentially contaminate nearby surface and groundwater sources.

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How to Conserve Water

  • Take short showers instead of baths.
  • Leave faucets off while brushing your teeth or shaving.
  • Wash dishes and clothes only when you have a full load.
  • Fix leaking faucets and toilets.
  • Replace older dishwashers, toilets, washers and shower heads with high-efficiency models.

Take care in what you put into your drains.

The following lists include items that should not be put into your OWTS:

Do Not Flush:
  • Cat litter
  • Cigarette butts
  • Condoms
  • Cotton swabs
  • Dental floss
  • Diapers
  • Feminine hygiene products
  • Paper towels
Do Not Flush or Pour Down Drains
  • Antifreeze
  • Non-household chemicals
  • Cooking oil
  • Gasoline
  • Grease
  • Motor oil
  • Paint or paint thinners
  • Pesticides

Household cleaners should be used in moderation so that they do not interfere with the biological processes that take place in an on-site wastewater treatment system.

Restrict the use of a garbage disposal or do not have one at all.

On-site Wastewater Systems - Do's and Don'ts

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Do:

  • Use water efficiently.
  • Use household cleaners in moderation.
  • Avoid putting grease and fat down the drain.
  • Keep records of repairs, pumping, inspections and any other pertinent maintenance actions.
  • Learn the location of your on-site wastewater treatment system.
  • Put a fence or other barrier to prevent damage to your on-site wastewater treatment system, if necessary.
  • Have the septic tank pumped periodically.
  • Take immediate action to correct problems when they arise.

Don't:

  • Drive over or park on any part of an on-site wastewater treatment system.
  • Use an on-site wastewater treatment system as a trash can.
  • Build anything over an on-site wastewater treatment system or cover the system with a hard surface such as concrete or asphalt.
  • Allow surface drainage of any kind to runoff over a drainfield.
  • Discharge water softener backwash or sump pump effluent into the septic tank.
  • Allow rain gutters or storm drains to discharge into or on top of an on-site wastewater treatment system.
  • Plant water-loving or deep-rooted plants over the system.
  • Allow sump pump effluent to enter the septic tank and/or drainfield.

On-site Wastewater Systems - Operating License Information

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What is the Operating License Fee? 

The Operating License fee is $20.

When is a new License required?

A new Operating License is required:- Prior to the sale or transfer of the property of a lot that contains an OSWTS.- At the time of Building Permit application submittal for a structure on a lot that contains an OSWTS. This includes any alteration or replacement of a structure served by an OSWTS*.- At the time of any change of designation request submittal (see PCZO § 103 – Definitions)*.- For any Commercial or Industrial OSWTS, every three (3) years.*Exemption. An Operating License is not required if a License has been issued within the previous six (6) years and the number of bedrooms is not increased.- Pennington County may require different frequencies for which an Operating License is required:

  • For non-residential structures.
  •  For unique, unusual or alternative OSWTS.
  • When the OSWTS is inadequate for the current use or size of the structure it serves, as determined by Pennington County.
  • When the property is located in close proximity to surface water or within the aquifer recharge area or overlay district.
  • For any other reason that Pennington County considers necessary to protect public health, the environment or prevent a nuisance.

Who performs the Observation required for the Operating License?

The Observation Form is completed and submitted by the certified Liquid Waste Pumper the property owner chooses. However, a property owner can request that Pennington County Personnel be present during the observation at no additional cost.

On-site Wastewater Systems - Sale, Transfer or Change

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Sale or Transfer of Property

The property owner or his/her agent must notify the Planning Department prior to the sale or transfer of property.  At that time, County Planning will determine if the On-site Wastewater Treatment System (OSWTS) on the property has a current Operating License.  If a valid license has not been issued, an Operating License shall be required prior to the sale or transfer of property. It will be the responsibility of the property owner containing an OSWTS to provide evidence to a prospective buyer or transferee, prior to closure, of compliance with Pennington County Zoning Ordinance § 331.

Change in Designation of Property

If a property owner requests any alteration or modification in the specified zoning, change in use (i.e. Conditional Use Permit) or change to platting for a parcel or property a valid Operating License is required prior to approval of the change in designation.

On-site Wastewater Systems - Service Provider Information

Certified Installers and Liquid Waste Pumpers