upper campbell corridor meeting
TRANSCRIPT
Upper Campbell
Corridor Meeting
Wednesday, August 28, 2013
6:30 – 8:30 PM
2
Welcome and Introductions
Supervisor Liz Archuleta
District 2
Coconino County
3
Opening Remarks
Lucinda Andreani
Coconino County
4
Tonight’s Goals
Review and Discuss Proposed 60% Plans
Review FLO2D Analysis Results
Review Next Steps
Opening Remarks
5
60% Designs
Reminder - Integrated Design Critical
Watershed Restoration on Forest and Lined
Channel from Forest Boundary to Upper
Campbell Ditch
Forest Measures Contingent on Neighborhood
Measures and Vice-Versa
Project Delivers Significant Flood Mitigation
for Entire Campbell Area & Also Beneficial to
Addressing Paintbrush Corridor
Significant Benefit to County Infrastructure
6
Design Assumptions
5 Year, 24 Hour Design Storm Accounting for 2 Years of Soil and Vegetative Recovery
Water Quantity is +/- 500 Cubic Feet Per Second
Water Velocity is +/- 8 Feet Per Second
Create No Adverse Impacts
Stay Within Existing Right-Of-Way
Re-Vegetate Measures on Forest and County Right-of-Way
60% Designs
7
Basis of Design – Two Sections
On-Forest Measures
Natural Channel Design, Inc.
Forest Boundary to Upper Campbell
Ditch
Shephard-Wesnitzer, Inc.
60% Designs
8
60% Design:
On-Forest Measures
Natural Channel Design, Inc.
Watershed Restoration Measures
On Forest
9
On-Forest Measures -
Key Considerations
Retain as Many Trees as Possible but Ensure
Full Value of Alluvial Fan Restoration
All Disturbed Areas will be Ripped, Seeded
and Mulched
Flows in Excess of Design Storm Will Flow in
Historic Flow Corridor
Private Properties Will See Flood Water from
Storms Greater than Design Storm; However,
First 500+ CFS is in the Channel and NOT on
Private Property
10
11
Pre-Final Design:
On-Forest Measures
12
Alluvial Fan Restoration
13
Transition Channel from Terminal
Fan to USFS Boundary
14
Tree Clearing and Excavation
Limits near Neighborhood
Middle fan in Thames, spreading water during flows
Log rundown and fan in Lenox.
17
Log Sill Across Fan
18
Log Run-Down Structure:
Brandis/Thames Watershed
19
Terminal Trench:
Brandis/Thames Watershed
20
Transition Channel Connects
to Neighborhood Channel
21
60% Design: Forest Boundary to
Upper Campbell Ditch
Shephard-Wesnitzer, Inc.
Forest Boundary to Upper Campbell Ditch
22
Off Forest Flood Mitigation –
Key Considerations
Reduce Impacts to Trees on Private Property
Adjacent to Right of Way – Moved Channel South by
14 Feet; Trees in ROW Will be Removed
Deliver Full Value of Channel Capacity
Provide Continued Historic Access Via Existing
Driveways by Using Box Culverts
Use Turf Reinforcement Mat to Reduce Erosion and
Enhance Re-Vegetation
23
60% Design: Forest Boundary
to Upper Campbell Ditch
24
60% Design
25
60% Design
60% Design
26 27
27
Turf Reinforcement Mat Lined
Channel
EXISTING CONDITIONS
PROPOSED CONDITIONS
28
Alice Drive Crossing
29
Driveway Box Culverts
Turf Reinforcement Mat
Brandis/Thames Watershed
30
31
Culvert Transitions
FLO2D Analysis Results
Chris Dusza, Civiltec Engineering, Inc.
FLO2D
Results
Any Frequency
5-Year, 100-Year, Etc.
Any Location
USFS
Private
Downstream
Every Grid Cell
Maximum Depth
33
No Adverse Impact Criteria
(NAI)
“An Approach by which the Action of Any Community
or Property Owner, Public or Private, will Not
Adversely Affect the Property Rights of Others”
Floodplain Management Initiative Developed by the
Association of State Flood Plain Managers
Does Not Mean No Development
Means that Any Adverse Impact that is or would be Caused
by a Project – or the Cumulative Impact of Projects – Must
be Mitigated
34
No Adverse Impact Criteria
(NAI)
Board of Supervisors Adopted NAI Criteria for
County Projects in the Schultz Flood Area Only, on
April 2, 2013
Does Not Apply to Private Property Owners or
Work in Other Parts of the County, Only County
Mitigation Projects in the Schultz Area
Criteria Based on FLO-2D Modeling of
Differences Between Pre- and Post-Mitigation
Water Depths and Velocities
35
No Adverse Impact Criteria
(NAI)
Water Depth
No More than .1 Foot increase at 5 Year Storm
No More than .5 Foot Increase at 10 Year Storm
No More than 1 Foot Increase at 100 Year Storm
Water Velocity
No Increase Less than 1 Foot/Second or 10% of
the Pre-Project Condition
36
37
FLO2D Results –
Five Year Storm Existing Condition
38
FLO2D Results –
Five Year Storm With Measures
39
FLO2D Results –
Five Year Storm Difference
40
FLO2D Results –
Ten Year Storm Existing Condition
41
FLO2D Results –
Ten Year Storm With Measures
42
FLO2D Results –
Ten Year Storm Difference
43
FLO2D Results –
100 Year Storm Existing Condition
44
FLO2D Results –
100 Year Storm With Measures
45
FLO2D Results –
100 Year Storm Difference
46
Adverse Impact Conclusions
No Adverse Impacts at the 5, 10 or 100 Year
Storms
Significant Reduction in Flood Impacts Resulting
from Five Year Design Storm Measures from Forest
Boundary and Downstream, Including County’s
$4M+ Infrastructure Investment
Reduces Impacts to Paintbrush Corridor and
Therefore Provides Opportunity to Reconsider Flood
Mitigation for this Highly Impacted Corridor
Excess Flows Go Where They Go Now
47
Moving Forward…
Lucinda Andreani
Coconino County
48
Total Preliminary Costs: $1,600,000 to $1,900,000
Benefits Entire Corridor
No Adverse Impacts
Project Meets Feasibility Criteria
49
Complete Utility Relocation Plans & Initiate Relocation in
September
Complete Engineering Plans, Costs and FLO-2D Analysis
Secure Any Necessary Temporary Construction Easements
Approvals
September 2013
Preliminary Construction Timeline – Weather Permitting,
Begin Construction On and Off Forest this Fall and Complete
Construction Spring 2014
Next Steps . . .
50
Resources
Please Direct All Questions and
Comments To:
Schultz Flood Hotline: (928) 679-8390
Schultz Flood Email:
51
Thank You!
Breakout Sessions
to Review Preliminary Plan Sets