SEMSWA has adopted and revised the Grading, Erosion, and Sediment Control (GESC) Manual and the Stormwater Management Manual for work in the City of Centennial.

• SEMSWA Stormwater Management Manual – The Stormwater Management Manual provides requirements for the planning, design, construction, and operation of stormwater facilities within the City of Centennial.
  • Update/Amendment History: Complete SMM updated January 2017, Chapter 14 (Stormwater Quality) updated July 2019.  20/10 calculator updated October 2020.
• SEMSWA Grading, Erosion, and Sediment Control (GESC) Manual – The Grading, Erosion, and Sediment Control (GESC) Manual, as amended, was adopted by the SEMSWA Board of Directors (Resolution 23-02) in January of 2023, effective February 17, 2023 for use within the City of Centennial portion of the SEMSWA Service Area. The current version replaces the June 2019 version.

The following documents may be required for some land development projects in the City of Centennial; please refer to your presubmittal notes or contact a SEMSWA Land Development Engineer to determine if any of these are required for your project.

• SEMSWA Addendum to City of Centennial Public Improvement Agreement
• Engineers Cost Estimate for Stormwater Public Improvements
• Permanent Drainage Easement Agreement
• Permanent Floodplain and Drainage Easement Agreement

The drainage checklists were formulated for use in the City of Centennial from Chapter 4 of the SEMSWA Stormwater Management Manual.

The Construction Design Checklists were formulated for use in the City of Centennial to ensure a complete set of Construction Drawings.

• Open Channel Design Checklist
• Street, Inlet, and Storm Sewer Design Checklist
• Bridge Design Checklist
• Conduit Outlets Design Checklist
• Culvert Design Checklist
• Detention Basin Design Checklist

The Permanent CM Standard Details below were adopted to be used in the City of Centennial and shall be used to comply with the criteria in the\ SEMSWA Stormwater Management Manual.  CAD .dwg files are available upon request.

• CM Materials Specifications (December 2020)
• Bioretention/Rain Garden (January 2020)General Details (January 2020)
• Grass Buffer (January 2020)Grass Swale (GS) (January 2020)
• Extended Detention Basin (EDB) and Modified EDB (January 2020)
• Sand Filter Basin (SFB) (January 2020)

The Design Engineer for land development projects in the City of Centennial will prepare an Operations and Maintenance (O&M) Site Plan to accompany the Operation and Maintenance Agreement for all post construction water quality facilities using the SEMSWA provided checklist.   

All O&M documents will be recorded with Arapahoe County Clerk and Recorder.

• Operations & Maintenance Agreement
• Operations & Maintenance Site Plan Checklist 
• Standard Water Quality Control Measure Facility Details

Standard Operating Procedure documents have been prepared for each SEMSWA Standard Water Quality Post Construction Control Measure to assist with inspection and maintenance protocols. 

• Extended Detention Basin Standard Operating Procedures 
• Grass Buffer - Grass Swale Standard Operating Procedures
• Bioretention - Rain Garden - Porous Landscape Detention Standard Operating Procedures
• Sand Filter Basin Standard Operating Procedures

Please view our City of Centennial Permitting Page