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DAB 303 - Municipal Separate Sewer System Permit

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The City of Colorado Springs is required to comply with the Municipal Separate Storm Sewer System (MS4) permit issued to the City by the Colorado Department of Public Health and Environment (CDPHE). The Permit regulates the discharge of stormwater runoff from the City’s municipal separate storm sewer system to local waterways through Best Management Practices (BMPs).

Stormwater management BMPs are control measures taken to mitigate changes to both quantity and quality of urban runoff caused through changes to land use and are required during construction and post-construction periods. Generally BMPs focus on water quality problems caused by exposed soils during construction and by an increase in impervious surface due to land development. BMPs are designed to reduce stormwater volume, peak flows, and/or nonpoint source pollution through evapotranspiration, infiltration, detention and filtration or biological and chemical actions.

In order to comply with the requirements imposed by the the Colorado Discharge Permit System (CDPS) permit, the City of Colorado Springs has adopted comprehensive stormwater management City Codes, and a Drainage Criteria manual Vol. II, which includes policies, procedures and Best Management Practice (BMPs) to manage the pollution from construction sites and postdevelopment.

Erosion and Stormwater Quality Plans are required for the following:

  • Excavation or Fill ≥ 500 CY, or
  • The grading of a site with land disturbance of 1 or more acres, or
  • Grading on any property with a natural slope in excess of 8%, or
  • Any combination of the above 3, or
  • Any grading or other disturbance of land in an area zoned Hillside Area Overlay Zone under City Code Section 7.3.504, or
  • Any grading or other disturbance of land in an area zoned Streamside Overlay Zone under City Code Section 7.3.508.E.1.F.

In addition, the City Engineer may require Erosion and Stormwater Quality Control Plans for minor land disturbing activities if deemed necessary.

Understanding the Differences

Erosion control practices are used to prevent erosion from occurring at construction sites with bare soils. Practices include mulch, erosion blankets, temporary and permanent seeding, and minimized or phased land clearing.

Sediment control practices are used to capture eroded sediments and keep them on-site and away from surface waters. Practices include silt fences, sediment basins, check dams, and erosion logs.

An example of a Porous Landscape Detention (PLD) Basin, also known as a raingarden. The PLD is a recommended BMP for stormwater management.

BMP Installation Sequencing

  1. Install temporary vehicle tracking at the construction entrance.
  2. Install all BMPs prior to any grading or excavation activities. This includes installing BMPs for storm inlets along the street frontage, perimeter control and protecting adjacent seeded or sodded lots.
  3. Stabilize stockpiles with BMPs to prevent sediment from reaching the street. Stockpiles may not be located in the street.

Construction BMP Maintenance

The builder/owner is responsible for maintaining and repairing all temporary BMPs on the lot throughout construction. This includes immediate rock, mud and soil removal from all streets that are a result of the project.

During final grading BMPs may be removed in order to complete final grading and sodding of the lot although the builder/owner is still responsible for any discharge leaving the site. If sodding of the lot is delayed, the contractor will be required to install BMPs until the sod can be installed.

Permanent BMPs require a maintenance agreement with the City of Colorado Springs ensuring the owner and all future owners will self-inspect annually and maintain their permanent BMP and gives the City the authority to maintain the BMP at the owner’s expense if the owner fails to do so. The City also inspects the permanent BMPs every 3 to 5 years.

Builder/Owner Responsibilities

The builder/owner is responsible for the installation, adequacy, and on-going inspection and maintenance of all lot specific erosion and sediment control devices, including inlets affected by their lots, as well as curb inlets along the street frontage. It is critical that sediment not be allowed to discharge to the local storm sewer system. The builder/owner is responsible for actions of all subcontractors, utility crews and delivery personnel at the work site as they relate to stormwater and erosion control.

City Inspections

It will be the policy of the City of Colorado Springs to encourage and enforce compliance with grading, erosion and stormwater quality control requirements by working with owners, contractors, builders, and developers during the design and implementation phases of a project to incorporate proper construction BMPs.

Additional Information

Colorado Department of Public Health and Environment

Urban Drainage and Flood Control District

Stormwater on