Confluence Park – Looking Back at the Safety-Related Success of the First Designed In-River Whitewater Park in the U.S. The whitewater river park at Confluence Park was constructed in 1974 - becoming the nation’s first designed park constructed in an active river. The whitewater course was totally re-designed by the author and rebuilt in 1995. Located within a very urbanized area and regulated floodplain, the structures making up the features act to form a diversion and stabilize this formerly degrading river channel. While the park is one of the most heavily utilized – particularly by novices – there have been no known drownings or serious injuries within this steep-gradient whitewater park. The various features of the park employ a number of design techniques and philosophies that have proven successful over the past almost 40 years. The safety related aspects of the park will be discussed and questions and discussion will be encouraged. Rick Mclaughlin is an engineer at the Mclaughlin Whitewater Design Group – a Division of Merrick & Company. He has been the design engineer on a number of whitewater and multi-purpose recreational projects since the early 1980s. Some of these include the current configuration of Confluence Park, the 1996 Olympic Whitewater Venue, a large river restoration, diversion, and whitewater project on the American River, a very large scale river restoration and whitewater project in Columbus Georgia and a fish passage and whitewater course in Delta Colorado.

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Confluence Park, Denver CO
Looking Back at the Safety-Related Success of the First
Designed In-River Whitewater Park in the U.S.
Presented to the:
April 2014

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Safety

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Safety

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Safety

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Safety
Union Avenue Boat Chutes, Sheridan, CO
One of the Most
Dangerous Venues in
Colorado
High Flows (not the problem)

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Initial Conclusion
 Is yours the same as a nationally recognized expert?

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Presentation Outline
Confluence Park Safety
Performance
Safety Criteria
 Criteria from the 1980s
 New Objectives and Criteria
Safety Features at
Confluence Park

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Confluence Park Safety Record
 No known fatalities or serious injuries since 1976
 Canoe Crunching and raft catching “holes” eliminated in
1995
 No changed hydraulic conditions in these 38 years of
operations
 Stepped Dam added in 1996 eliminated dam related
safety issues - even in this heavily used reach.
 Boated by intermediate kayakers in the 10-year flood
event.

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Copyright © 2012 Merrick & Company - All rights reserved.
Presentation Outline
Confluence Park Safety
Performance
Safety Criteria
 Criteria from the 1980s
 New Objectives and Criteria
Safety Features at
Confluence Park

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Design Criteria for Recreation Structures
http://www.udfcd.org/downloads/down_critmanual.htm
http://cwcb.state.co.us/technical-resources/floodplain-
stormwater-criteria-manual/Pages/main.aspx

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Emphases of Existing UDFCD Manual
 Avoidance of Overly Retentive Hydraulics
 Portages
 +/- Design Suggestions
 Signage/Barriers

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Emphases of Existing UDFCD Manual
Overly Retentive Hydraulics

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Emphasis of Existing Manual
Signage/Barriers
Wide Ties and Polyester - Not Good
Barriers - Not good

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Emphasis of Existing Manual
Signage/Barriers
No Standardized
Messages or
Graphics
(This sign – Not
Good)

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Other Recommendations in Existing Manual
Confluence Park Design included these:
 .Issues as previously outlined
 Maximum drop height of 4 feet. If more, a physical
hydraulic model may be necessary.
 Determine characteristics to be compatible with public
safety and recreational boating.
 Assess stability of the structure.
 Portage paths.
 Obtain peer review on the preliminary design.
 Allow for follow-up rock adjustment after completion,
especially for boat chutes.

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 Use a Froude number, Fr, less than 1.5 at the toe of the
drop.
 Consider the slope of the downstream face of a sloping
drop; 10(H) to 1(V) is common.
 Provide boat chute with pilot rocks for routine boat
passage of drop.
 Use grouted sloping boulder or appropriately sized large
ungraded sloping boulder structure.
 Warning Signs
Other Recommendations in Existing Manual
Confluence Park Design did not include These:

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Emphasis of Existing Manual
Summary:
 Criteria and suggestions have demonstrated
value and are still of upmost priority.
 But over the past decade we have learned a
lot more and the criterion are dated just like
these kayakers.

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Updates
Additional “Suggestions”
Global Objectives:

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Proposed Updates
Additional “Suggestions”
Two-Dimensional Modeling
• Complex Situations
• Typical Applications

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Proposed Updates
Additional “Suggestions”
Summary of Other Suggestions:

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Proposed Engineering Related Criteria
Obvious?

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Safety is More Challenging than Ever
Aesthetics & Permitting
(Grout - Bad)
Innovative techniques to
reduce grout have been
successful, but ???
Pinned Boulder Technique used on the 2013 World Freestyle
Championships, Nantahala River , North Carolina

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Photos: USBR
Multiple Slot Baffled
Safety is More Challenging than Ever
Integration with Fish Passage

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Safety is More Challenging than Ever
Diversion and Floodplain Objectives
 At the New Whitewater River Park in Boise, ID: Surfers
and Kayakers play in and around Gate and Intake
Apparatus

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Safety is More Challenging than Ever
Accommodating a Wide Range of Users

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Safety is More Challenging than Ever
Limited Budgets

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Presentation Outline
Confluence Park Safety
Performance
Safety Criteria
 Criteria from the 1980s
 New Objectives and Criteria
Safety Features at
Confluence Park

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Safety Features of Confluence Park

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Man-Made Jetty
Design: Durable Construction Techniques

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Thank You
Richard McLaughlin, PE
McLaughlin Whitewater Design Group
www.mclaughlinwhitewater.com
rick@mclaughlinwhitewater.com
303-964-3333