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Granby and sable ditch major drainageway plan (MDP)

Located in rapidly developing Aurora, Colorado, the 2700-acre Sable and Granby Ditch Watershed has not been independently studied since the 1990s. Spanning from the downstream end of Buckley Air Force Base to roughly I-225 and E 30th Avenue, this watershed is home to several Aurora Public Schools, the new Citadel Development, several houses of worship, community facilities, commercial and retail facilities, and Aurora residences, as well as housing redevelopment opportunities at several vacant or underutilized parcels. 

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Focusing on updating the watershed and floodplain, the Granby and Sable Ditch MDP Project will include coordination with sponsors Urban Drainage and Flood Control District and the City of Aurora, as well as stakeholders from Aurora's business owners and citizenry. To hear more about this project as we move forward, please check out the "Meetings" tab below, which will be updated regularly with new information and upcoming meetings.

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To mitigate current flooding and prevent future flooding, this study and master plan will provide updated baseline hydrology, a CLOMR/LOMR, hydrographs for watershed and subwatershed, HECRAS and CUHP modeling, alternatives analysis for flood mitigating Capital Improvement Projects (CIPs), hydraulic analysis, conceptual design, and integration into the City’s Digital Stormwater Master Plan.

GOals

  • ​Define the 100-year floodplain

  • Update Aurora's floodplain layer and prioritization tool for stomwater planning in Aurora

  • Update the floodplain for the watershed

  • Identify and analyze outfalls for Aurora Parks

  • Update hydrology for the watershed

  • Update Aurora's Digital Stormwater Master Plan

  • Identify ways to mitigate flooding in the area

  • Identify Capital Improvement Projects in the watershed

  • Provide conceptual design for the preferred alternative for mitigating flood in the area

Critical issues

  • Databases currently show Granby Ditch ending at Colfax, and this study will extend the boundary

  • Aurora Public Schools and Buckley Air Force Base may have private or P3 developments that impact the imperviousness in the watershed

  • Updating the watershed will impact Aurora's CIP list

  • Current flooding shown upstream of the current "end point" of the watershed (at Colfax)

  • Updating existing and future conditions in stormwater modeling will impact future stormwater planning to plan for development and densification in the area

  • Inlets at Colfax are undersized, which results in overtopping of Colfax

  • Flooding has occured at Hinkley High School, although no structures were impacted

  • High Line Canal and various ponds are located within the watershed and should be analyzed for flood impacts

Project Sponsers

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Project Schedule

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Next public meeting

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Subject: Granby/Sable Public Meeting

When: October 23, 2019

Time: 6:30 PM - 7:30 PM

Where: Aurora Municipal Center, 15151 East Alameda Parkway, Aurora, CO 80012 - The Aurora Room (Conference Room)

  • Project Maps
    Grandby Sable Watershed Map Approximate Watershed Limits
  • Meetings
    Subject: Granby/ Sable Public Meeting When: Wednesday, October 23, 2019 6:30 PM-7:30 PM (UTC-07:00) Mountain Time (US & Canada). Where: Aurora Municipal Center – Aurora Room; 15151 East Alameda Parkway, Aurora, CO 80012
  • Reports
    The Draft Granby Sable MDP Alternatives Analysis, dated November 2019, can be downloaded by clicking the following link: Draft Granby Sable MDP Alternatives Analysis The Draft Granby Sable MDP Conceptual Design, dated February 2020, can be downloaded by clicking the following link: Draft Granby Sable MDP Conceptual Design The Final Granby Sable MDP Report, dated June 2020, can be downloaded by clicking the following link: Granby Sable MDP Report NOTE: These are very large files and may take several minutes to download.
  • Additional Info & Useful Links
    City of Aurora Digital Stormwater Master Plan 1977 Granby and Sable Ditch FHAD (Gingery Assoc) 1990 Granby and Sable FHAD (Kiowa Engineering) 1990 Granby and Sable Drainageways MDP, Phase A (Kiowa Engineering) 1991 Granby and Sable Drainageways MDP, Phase B (Kiowa Engineering) 2001 Granby and Sable Ditch (Muller Engineering) 2006 Granby Ditch Inlet I-225 and Colfax (Muller Engineering) 2009 Sable Ditch Detention Pond and Floodplain Study (Muller Engineering) 2010 Sable Ditch Detention Pond Colfax and Jasper Part I (Muller Engineering) 2010 Sable Ditch Detention Pond Colfax and Jasper Part II (Muller Engineering)
  • Contact
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