This was a presentation regarding how multi-use greenways can be designed and constructed with no adverse impact to the 100-yr floodplain. I co-presented this at the 2005 conference of the Association of State Floodplain Managers.

1. with no Adverse Impact
Colorado Examples
John Pflaum, P.E.
ASCG Incorporated
Cindy Thrush, P.E.
Urban Drainage & Flood Control District

2. Denver Metropolitan Greenways
Born from a Flood

3. Evolution Of Denver’s Greenways
 1965 Major Flood with Millions in Damages
 1969 Urban Drainage & Flood Control
District Forms
 1973 Significant Flood
 1974 Platte River Development formed
 1976 Initial Confluence Project Completed
 1976 to 1996 South Platte River Greenway
Extended North & South
 1980’s to Present – Greenways Developed
along Tributary Drainageways
 1996 to Present – Second Wave of South
Platte River Greenway Improvements
(Downtown Riverfront and Suburban
Greenways)

4. The Urban Drainage and Flood Control District
and
Public Agency Partnering

5. Who is the Metro Denver Urban Drainage
and Flood Control District?
Quasi-governmental agency established by the
Colorado State Legislature in 1969 to assist local
governments in 6 counties, 34 cities with multi-
jurisdictional drainage and flood control projects.

6. Who is UDFCD? Continued
 Governed by 20 member Board Of Directors
18 – Elected Officials
2 – Professional Engineers
 Budget is about 15 million each year, funded by
property taxes. 20 full time staff, all engineering
design, project construction and maintenance
work contracted out to private industry.

7. MAJOR AREAS OF ACTIVITY
 Drainageway Maintenance
 Capital Improvement Projects
 Master Planning
 Floodplain Management
 Flood Warning
 NPDES Permitting - Storm
Water Quality
 Criteria Development - Manuals
 Floodplain Preservation
 New Development Plan Review

8. Map of UDFCD
Boundaries
 6 Counties
 1,608 square miles
 1,600 miles of
major drainage ways

9. Denver Drainageway
Characteristics
 Semi-arid climate, 15 inches of rain per year
 Most erosion and flooding due to thunderstorms
 Only 6-8 creeks have more than 5 cfs base flow
 About 95% are natural open channels (only a
small portion contained by levies)
 Elevation: 5,280 ft – “Mile High City”
 Population 2.2 Million

10. Partnering on Trail Projects
for Over 35 Years
 Work with Cities, Counties, Park Districts
 Maintenance access trails proposed in Drainageway
Master Plans since the 70’s
 Drainageways platted in separate tracts of land
dedicated to Park Districts or HOAs
 Denver area’s network of trails is linked together
through the drainage ways
 Many projects have combined stream restoration
and trail construction/maintenance together

11. UDFCD Trail Participation Policy
 Trail must serve a maintenance access need for a
drainage way
 Right-of way, design, construction and restoration
maintenance eligible for funding
 Participation limited to 50% of the design and
construction cost for a “soft” surface trail, or 25%
of a concrete trail
 Design must be reviewed by UDFCD, either party
can manage the project

12. Planning and Designing Greenways
Planning:
 Identify watershed, jurisdictions, land ownership
 Involve public
 Continuity, connectivity, accessibility
 Resource preservation and protection
 Floodplain and geomorphology
 Buffering, vistas, views
 Education and stewardship
 Signage and way-finding
 Multiple use benefits
 Safe and maintainable

13. Planning
and Designing Greenways
Design:
 Multi-Disciplinary Team
 Public officials/representatives
 Engineers
 Surveyors
 Landscape Architects
 Ecologists
 Biologists
 Right-of-way agents

14. Trail & Greenway Routing Considerations
No Adverse Impacts To Floodplain
 Minimize Impacts to Stream Riparian Areas

15. Trail Grading to Avoid or
Minimize Floodplain Impacts

16. South Platte Greenway
at Commons Park

17. Sand Creek Greenway

18. Stream Crossings
 Bridges
 Low Flow Crossings
 Informal Boulder Step Crossings
 Must be designed to withstand flow velocities during
storm events

19. Low Flow Crossings
Appropriate for Wide Floodplain Conditions
Designed for Overtopping
 Prefab. or Reinforced Concrete Construction
 Fixed or Collapsible Handrails
 Erosion Protection at Corners
 Often Combined with Channel Stabilization Measures
Goldsmith Gulch at Bible Park Grange Hall Creek

20. Big Dry Creek Greenway

21. Cherry Creek

22. Bridges
 Span 100-yr. Floodplain
 Durability/Low Maintenance
 Safety and Rub Rails
 Concrete Deck Preferred

23. Cherry Creek

24. Centennial Bridge over
Cherry Creek
at Confluence Park

25. 16th Street Bridge over South
Platte River Downtown Denver

26. South Platte River
Greenway at
Cuernavaca Park

27. Big Dry Creek
Trail Connection

28. Underpasses
 Safe Grade Separation from Vehicles
 Often Inundated Several Times per Year
 Ramp to Street Grade Desirable
• Safe Route During Flooding
• Access Point for Public & Maintenance
 Separate Underpass Structures
• More Costly, but:
• Separated from Streamside Environment
• Can Provide Supplemental Flood
Capacity

29. Big Dry Creek Tail
Underpasses

30. Sand Creek Greenway

31. Willow Creek at
Dry Creek Road

32. Summary
Sensitive Routing – Avoid Fills

33. Be Creative to
Overcome
Problems

34. Encourage Citizen Participation

35. Celebrate your Success!
Happy Trails!