Stapleton International Airport (Stapleton) served as the primary airport for Denver prior to 1995. Westerly Creek was piped under the runways in a 108-inch pipe, yet this system was unable to convey the 100-year flood. Stapleton’s 4,700 acres, which represents the nation’s largest urban infill development project, is currently being redeveloped by the City and County of Denver and Forest City Development (Forest City).

Matrix was retained by Forest City to restore an 8,000 foot reach of Westerly Creek by creating an open channel to reduce the flood hazard to adjacent properties. The restoration included creation of riffle and pool sequences, in-stream habitat structures, meanders, and reestablishment of native riparian vegetation.  The Westerly Creek project transformed the site into an open space corridor with a broad open channel as a park amenity. 

Matrix’s work included:

  • Hydrologic Modeling:  Developed a CUHP/SWMM drainage master plan model for the entire Stapleton site. The hydrologic model routed drainage through numerous regional detention and water quality ponds to establish drainage patterns and size infrastructure for detailed cost projections and budgeting.
  • Channel Restoration Design:  Prepared construction documents for a channel restoration and flood control on Westerly Creek.  Matrix obtained 404 permits and a FEMA Conditional Letter of Map Revision (CLOMR) to enable construction to occur.
  • Natural Channel Design:  Robert Krehbiel and Jane Kopperl worked closely together to create a vegetative and hard structure restoration project including an open channel design; creation of 8 acres of wetlands; riffle and pool sequences; in-stream habitat structures; and reestablishment of riparian vegetation.
  • Water Management Structures:  Designed creative structures including outfalls, drop structures, and grade management structures as waterfall features to be interactive with the community and to enhance the natural trail system throughout the corridor.
  • Water Quality Management:  Provided engineering support in the development of a specialized, multi-layered “treatment train” approach for application to each sub-basin. The plan established a balance between onsite pretreatment needs and regional end-of-pipe water quality ponds situated in open space areas.
  • Drainage Infrastructure Design:  Prepared design and construction documents for 29th Avenue, Martin Luther King Boulevard, and regional stormwater detention facilities.

404 Clean Water Act Permitting:  Submitted an application to the U.S. Army Corps of Engineers for river restoration and received authorization to proceed under a nationwide permit.

Services included:

  • Watershed Planning
  • Infrastructure Assessment and  Master Planning
  • Hydraulic Modeling and Analysis
  • River Restoration and Channel Design
  • Channel Stability Analysis
  • Construction Documents
  • Water/Wastewater Treatment Design
  • Sanitary Sewer Infrastructure Design
  • Floodplain Mapping
  • Public Involvement