North Paintbrush

Corridor Meeting

Thursday, February 20, 2014

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

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60% Designs

Reminder - Integrated Design Critical

Watershed Restoration on Forest and Off

Forest Conveyance Through the Neighborhood

to Lower Campbell Avenue Ditch

Forest Measures Contingent on Neighborhood

Measures and Vice-Versa

Project Delivers Important Flood Mitigation to

the Highly Impacted North Paintbrush

Corridor

6

Design Assumptions

5 Year, 6 Hour Design Storm Accounting for ~2 Years of Soil and Vegetative Recovery

Design Peak Flow Rate is 258 Cubic Feet Per Second

Create No Adverse Impacts

Stay Within Existing Right-Of-Way and New Easements on Private Property

Re-Vegetate Measures On and Off Forest

Provide Fencing Along Easements

60% Designs

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60% Designs

Design Through Neighborhood Reflects Feedback

from Initial Corridor Meeting & Individual Meetings

All Easements Secured From Private Property

Owners & Now Securing Mortgage Releases

Engineering Identified Need for Additional Sediment

Reduction

Less Alluvial Fan Area On Forest

South to North Conveyances Occur on Flat Grades

Reduce Future Maintenance Need & Cost

8

Basis of Design – Two Sections

On-Forest Measures

Natural Channel Design, Inc.

Forest Boundary to Lower Campbell

Ditch

Civiltec Engineering, Inc.

60% Designs

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60% Design:

On-Forest Measures

Allen Haden

Natural Channel Design, Inc.

10

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 260+/-

CFS is in the Conveyance and NOT on Private

Property

Paintbrush On–Forest Measures

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Middle Fan in Thames, Spreading Water During Flows

Log rundown and fan in Lenox.

Log rundown and fan in Lenox15

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Log Sill Across Fan

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Log Run-Down Structure:

Brandis/Thames Watershed

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Terminal Trench:

Brandis/Thames Watershed

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Transition Channel Connects

to Neighborhood Conveyance

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60% Design:

Off-Forest Measures

Chris Dusza, P.E.

Civiltec Engineering, Inc.

21

Off Forest Flood Mitigation –

Key Considerations

Limited Right of Way Available for Improvements

Multiple Road and Driveway Crossings

Utility Considerations and Conflicts

Easements Needed from Multiple Property

Owners

Need for Additional Sediment Reduction and

Storage

Coordination of Corridor Improvements with ILM

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60% Design: Forest Boundary to

Lower Campbell Ditch

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TRM Channel

60% Design: TRM Channel

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TRM Channel

Wupatki Trails

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60% Design: Gabion-Concrete

Channel

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Gabion-Concrete Channel

Lower Campbell Avenue

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60% Design: Pipe

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60% Design: Sediment Reduction Site

29

FLO2D Analysis

Chris Dusza

Civiltec Engineering, Inc.

FLO2D

Results

Any Frequency

5-Year, 100-Year, Etc.

Any Location

USFS

Private

Downstream

Every Grid Cell

Maximum Depth

30

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 Mitigated31

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

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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

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345 yr./6 hr. Storm - Existing Condition

355 yr./6 hr. Storm – Post Measures

3610 yr./6 hr. Storm - Existing Condition

3710 yr./6 hr. Storm – Post Measures

38

FLO2D Results –

Five Year Storm Existing Condition100 yr./6 hr. Storm - Existing Condition

39100 yr./6 hr. Storm – Post Measures

Adverse Impact Conclusions

No Adverse Impacts at the 5, 10 or 100 Year

Storms

Important Reduction in Flood Impacts Resulting

from Five Year Design Storm Measures from

Forest Boundary and Downstream

Reduced Impact to the Paintbrush Corridor and

Therefore Provides Opportunity to Construct Flood

Mitigation for this Highly Impacted Corridor

Excess Flows Go Where They Go Now

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Moving Forward…

Lucinda Andreani

Coconino County

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Total Preliminary Costs: $2.9 Million to $3.2 Million

Benefits Entire Corridor

No Adverse Impacts

Secured Easements

Project Meets Feasibility Criteria

43

Secure Cost Share Approval from NRCS

Secure Final Approvals from Utilities

Complete Engineering Plans

Secure Any Necessary Temporary Construction

Easements

Approvals – FCD Board of Directors, NRCS & USFS

Target - April 1, 2014

Preliminary Construction Timeline – Weather

Permitting, Begin Construction On and Off Forest in

Early April and Complete Construction by June 30th

Next Steps . . .

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Resources

Please Direct All Questions and

Comments To:

Schultz Flood Hotline: (928) 679-8390

Schultz Flood Email:

schultzfloodmitigation@coconino.az.gov

Schultz Flood Website:

www.coconino.az.gov/schultzfloodinform

ation

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Thank You!

Breakout Sessions

to Review Preliminary Plan Sets