Planning / Highway Department Storm Water Plan

The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

What is Storm Water?

Storm Water is water from precipitation (such as rain or snowmelt), over-irrigation from sprinklers, wash water from hoses or hydrants, any other water that flows over the ground surface and enters a drainage way. This water picks up debris, sediment, nutrients, bacteria, and other pollutants that eventually flow, untreated, into creeks, streams and rivers. Impervious surfaces such as sidewalks, driveways, rooftops, and streets prevent storm water from soaking into the ground and therefore produce runoff.

Why does Pennington County have a Storm Water Management Program?

As a result of federal regulations, referred to as the Phase II Storm Water Rule, storm water discharges from small Municipal Separate Storm Sewer Systems (MS4s) are required to obtain a storm water permit for their system. Pennington County was issued such a permit.

As part of the storm water permit, Pennington County is required to develop and implement a Storm Water Management Program. The program must address and implement the following control measures:

  1. Public education and outreach;
  2. Public participation/involvement;
  3. Illicit discharge detection and elimination;
  4. Construction site storm water runoff control;
  5. Post-construction storm water management; and,
  6. Pollution prevention/good housekeeping for municipal operations

Storm Water Management Plan

Please take a few minutes to answer some questions regarding stormwater in Pennington County.

Stormwater Survey

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Storm Water Plan - Construction & Best Management Practice

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

Do you need a Pennington County Construction Permit?

All land-disturbing activities, including clearing, grading, stockpiling, and excavation that disturb 10,000 square feet or more requires a Pennington County Construction Permit. 

Do you need a National Pollutant Discharge Elimination System (NPDES) Storm Water Construction Permit?

All land-disturbing activities, including clearing, grading, and excavation that disturb 1 or more acres are required to be covered under the South Dakota Department of Environment and Natural Resources NPDES construction storm water permit prior to land disturbance.

What is a BMP?

A BMP (Best Management Practice) is a method used to prevent or control storm water runoff and the discharge of pollutants, including sediment, into local waterbodies.  Silt fences, inlet protection and site-stabilization techniques are typical BMPs on a construction site.  BMP and final stabilization requirements can be found in the Pennington County Storm Water Quality Manual.

Storm Water Plan - Erosion & Sediment Control for Construction Sites

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

What is Erosion and Sediment Control?

Erosion and sediment control practices are used to prevent runoff from occurring at construction sites with disturbed soils.  These practices may include silt fencing, wattles, and erosion mats and are often referred to as Best Management Practices or BMPs.  Pollutants that can leave a construction site include sediment, sanitary waste, debris, oil and grease, chemicals, and concrete wash water.  Implementation of BMPs at construction sites can significantly reduce runoff from occurring.  Sediment is the largest source of pollution from construction sites.

Why is Erosion and Sediment Control Important?

Construction activities without proper erosion and sediment controls can contribute large amounts of sediment and pollutants to streams, creeks, rivers and lakes.  Sediment can cloud the water and make it difficult or impossible for aquatic plants to grow.  It can also destroy aquatic habitats.  In addition, the U.S. Environmental Protection Agency makes it illegal to discharge sediment-laden water and/or construction-related pollutants to storm sewers or waterways.  By keeping sediment and other pollutants out of streams, creeks, and rivers, you can maintain water quality for drinking, recreation, wildlife, and aquatic life.

Soil Erosion and Sediment Control Tips:

  • Design site to infiltrate stormwater into the ground and keep out of storm drains and drainage ways.
  • Keep sediment on site.
  • Maintain all BMPs to ensure their effectiveness throughout the life of the project.
  • Minimize the amount of exposed soil on the site.
  • Protect defined channels immediately with measures adequate to handle the storm flows expected.
  • Reduce the velocity of stormwater both onto and away from project area.

Storm Water Plan - Illicit Discharge Detection and Elimination

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

What is an Illicit Discharge?

An illicit discharge is considered to be anything entering the storm drains or system that is NOT storm water.

Examples of illicit discharges include dumping or spilling of materials, such as oil, grease, paint or other sources of pollution, into the storm drains, culverts, drainage ways or ditches.

Reporting Procedure

If you notice something that may be considered an illicit discharge, please call 605-394-2186 to report the problem.

Notification of Spills

As soon as any person responsible for a facility or operation, or responsible for emergency response for a facility or operation, has information of any known or suspected release of materials which are resulting or may result in illicit discharges or pollutants discharging into storm water, the Storm Drain System, or Waters of the State, said person shall immediately notify emergency response agencies of the occurrence via emergency dispatch services. 

In the event of a release of non-hazardous materials, said person shall notify the Planning Director and the South Dakota Department of Environment and Natural Resources no later than the next business day.  Verbal notice, in person or by phone, shall be confirmed by written notice, addressed and mailed to the Pennington County Planning Department (900 Concourse Dr., Suite 160, Rapid City, SD 57703), and postmarked within three (3) business days of the verbal notice. 

If the discharge of prohibited materials emanates from a commercial or industrial establishment, the owner or operator of such establishment shall also retain an on-site written record of the discharge and the actions taken to prevent its recurrence.  Such records shall be retained for at least seven (7) years.

Storm Water Plan - Pollution Sources

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

As water flows over roads, sidewalk, driveways and other impervious areas, it picks up debris, chemicals, sediment and bacteria. Storm water is not cleaned before it reaches creeks and streams. Storm water is considered non-point source pollution. Non-point source pollution originates from many different places or a widespread area. Everyone contributes to this type of pollution when disposing of fertilizers, pesticides, oils, greases, pet wastes and trash improperly.

If you need to dispose of household hazardous materials, please contact Rapid City’s Material Recovery Center at 605-355-3496.

Examples of Non-point Source Pollution

  • Antifreeze and Metals
  • Bacteria and Pathogens – improperly treated sewage and animal wastes
  • Chemicals and Cleaners
  • Litter and Debris
  • Nutrients and Pesticides – fertilizers, decaying lawn debris, detergents, sewage and animal wastes
  • Oil and Grease
  • Paint
  • Sediment – construction activities, farming, logging, mining and runoff from neighborhoods and businesses
drain

Example of pollution in a storm water drainage area.

Storm Water Plan - Pollution Prevention

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

How You Can Help

Many household chemicals used everyday may be toxic to creeks and streams. The United States Environmental Protection Agency estimates that the average household in the United States generates 20 pounds of hazardous waste from their households every year.

If you need to dispose of household hazardous materials, please contact the Rapid City Solid Waste Division at 605-355-3496.

Common Hazardous Wastes Found in the Home

  • Automotive
    • Antifreeze
    • Batteries
    • Brake Fluid
    • Degreasers
    • Fuel
  • Home Improvement
    • Cleaners
    • Glues
    • Paint, Paint Stripper and Paint Thinner
    • Sealers
    • Tar
    • Varnish
  • Household Items
    • Aerosol Products
    • Batteries
    • Drain Cleaner
    • Fluorescent Lights
    • Mothballs
    • Solvents
    • Thermometers (with mercury)

Storm Water Plan - Storm Drain System

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

Where do Storm Drains Go?

It is a common fallacy that stormwater is treated. Storm drains connect to a system of pipes and culverts that drain directly to a creek or stream, without treatment. Storm drains were created to prevent flooding and transport water off of impervious surfaces such as driveways and roads. When pollutants, such as leaves, oil, paint and sediment are disposed of in storm drains, they can carry pollutants directly to the creek or stream and become clogged.

Pollutants from storm drains contaminate creeks and streams and can have adverse affects on plants, animals, fish and people. In order to help people understand that storm drains transport water and pollutants directly to nearby creeks and streams, Pennington County will begin labeling all of the storm drains within urbanized areas.

Storm Water Plan - Urbanized Areas

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The Storm Water Management Plan is jointly managed by the Planning Department and Highway Department.

Municipal Separate Storm Sewer Systems (MS4)

What is a MS4?

A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains):

  1. Owned and operated by a state, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, storm water, or other wastes, including special districts under state law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the Clean Water Act that discharges to waters of the United States;
  2. Designed or used for collecting or conveying storm water;
  3. Which is not a combined sewer;
  4. Which is not part of a Publicly Owned Treatment Works as defined at 40 CFR §122.2; and,
  5. Determined by the Environmental Protection Agency from census data (Urbanized Areas).

What is an Urbanized Area?

An Urbanized Area is an area that contains a population greater than 1,000 people per square mile. Urbanized Areas are determined by the Census Bureau.

The Urbanized Areas located within Pennington County include four major areas: Rapid Valley, Green Valley Estates, Colonial Pine Hills and Universal Drive.

Please take a couple of minutes to answer some questions regarding stormwater in Pennington County.

Stormwater Survey