Final Presentation - Alluvial Fan Floodplains_maxcomp
1. Mark Edelman, AICP – Arizona State Land Department
Sallie Diebolt – U.S. Army Corps of Engineers
Doug Williams, AICP – Flood Control District of Maricopa County
Source: "Gigantic Alluvial Fan Being Uplift by New Fault" by Wing‐Chi Poon ‐ self‐made; along North Highway in Death Valley National Park, California, USA.. Licensed under CC BY‐SA 2.5 via Commons – https://commons.wikimedia.org/wiki/File:Gigantic_Alluvial_Fan_Being_Uplift_by_New_Fault.jpg#/media/File:Gigantic_Alluvial_Fan_Being_Uplift_by_New_Fault.jpg
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US Army Corps of Engineers
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Section 404 Clean Water Act
Permitting
Sallie Diebolt
Chief, Arizona Branch
Regulatory Division
Los Angeles District
November 5, 2015
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Reporter Richard Ellis dips his hand in the
Cuyahoga River on a boat trip in the 1960s
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August 1, 1969
“No Visible Life. Some river!
Chocolate-brown, oily, bubbling with
subsurface gases, it oozes rather
than flows. "Anyone who falls into
the Cuyahoga does not drown,"
Cleveland's citizens joke grimly. "He
decays." The Federal Water
Pollution Control Administration
dryly notes: "The lower Cuyahoga
has no visible life, not even low
forms such as leeches and sludge
worms that usually thrive on
wastes." It is also—literally —a fire
hazard.”
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Regulatory Mission
• Protect aquatic resources
• Allow reasonable development
• Fair, timely, and balanced permit
decisions
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What is Section 404?
Section 404 of the Clean Water Act (1972, as
amended)
Required for the discharge of dredged or fill
material into waters of the U.S.
Common projects are construction, maintenance,
and repair activities in the waters of the U.S.
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Regulatory Process
1) What is the scope of the project?
2) Is there geographic jurisdiction?
3) Are there regulated activities?
4) What type of permit is needed?
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Regulator’s Process
1) What is the scope of the project?
2) Is there geographic jurisdiction?
3) Are there regulated activities?
4) What type of permit is needed?
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Scope of Project
Location information
• Vicinity map
• Coordinates
• Directions to site
• Permission to access
Clearly define project area boundary
Describe all proposed activities
Single and complete project
Recent, good quality aerial photos
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Regulatory Process
1) What is the scope of the project?
2) Is there geographic jurisdiction?
3) Are there regulated activities?
4) What type of permit is needed?
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Geographic Jurisdiction
Physical and biological indicators of flow
Wetland boundary
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Geographic Jurisdiction
Rivers/Streams
Dry Washes/Arroyos
Ponds/Lakes*
Wetlands*
Constructed Canals/Laterals*
* fed by or conveys natural drainage
flows
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Two Types of Jurisdictional
Delineations
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Preliminary JD
- Non-Binding
- Assume all likely areas are jurisdictional
- No Significant Nexus Analysis
- Does not require EPA approval
- Allows projects to move forward
Approved JD
- Binding
- Definitive re non-jurisdictional areas
- Significant Nexus Analysis
- Requires EPA approval
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Clean Water Rule
Rulemaking to clarify jurisdiction under
Section 404
Current status???
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Regulatory Process
1) What is the scope of the project?
2) Is there geographic jurisdiction?
3) Are there regulated activities?
4) What type of permit is needed?
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Regulated Activities
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Any activity that results in ground-disturbing
activities (i.e., dredging or filling) within waters
of the U.S.
• Fills (e.g., for construction of buildings, parking
lots, etc.)
• Roads (culverts)
• Rip-Rap
• Grading (moving material from one area to
another within the waterway)
• Stockpiles
• Utility Lines
• Mechanized removal of vegetation
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What Is NOT Regulated Under
Section 404?
Excavation “Scoop and haul”
Fences
Driving
Herbicides
Other activities regulated by Section 402
(SWPPP)
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Regulatory Process
1) What is the scope of the project?
2) Is there geographic jurisdiction?
3) Are there regulated activities?
4) What type of permit is needed?
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Types of
Section 404
Permits
Individual
§ 404 Permit
Impacts to
Waters
of the U.S.
any amount of
wetland impacted
No § 404
Permit
Non-Notifying
Nationwide
§ 404 Permit
No
Impacts
Impact
less than or
equal to
1/10 acre
Notifying
Nationwide
§ 404 Permit (PCN)Or may affect
cultural resources
or federally listed species
Impact greater
than 1/10 acre,
but less than
or equal to
½ acre
•2–4 months +
•Jurisdictional
delineation
required
Start work today!
Obey conditions.
6 months to 1 year +
If need jurisdictional
delineation,
Corps review is
usually 2–3 months
Start work today!
No conditions!
Impact greater than
½ acre or
Regional
General
Permit
63
Certain emergency
situations
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Nationwide Permit (NWP)
Program
Corps reviews and reissues the NWP program
every 5 years
Current set of NWPs:
Issued March 19, 2012
Expire March 18, 2017
Verification letter from Corps is generally valid until
March 18, 2017
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RGP 63 Definition of
Emergency
An “emergency situation” is present where there is a clear,
sudden, unexpected, and imminent threat to
life or property demanding immediate action to prevent or mitigate
loss of, or damage to, life, health, property or essential public
services (i.e., a situation that could potentially result in an
unacceptable hazard to life or a significant loss of property if
corrective action requiring a permit is not undertaken immediately).
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Sequential Approach
Avoid
Minimize
Mitigate
Document Compliance with permit terms
and conditions
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Compensatory Mitigation
Comply with the Mitigation Rule
Mitigation Banks
In-lieu fee programs
Prescott Creeks Preservation Association
Arizona Game and Fish Department
La Paz County Endangered Species Fund
Superstition Area Land Trust
Tucson Audubon Society
Permitee-responsible mitigation
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Plan Ahead!
Designate team member responsible for
Section 404 matters – have Section 404
agenda item in meetings
Early and continuous resource
assessment
• Identify jurisdictional waters
• Establish resource values (cultural,
biological)
• Avoid and minimize impacts where practical
• Continuously reassess project direction for
Section 404 impacts
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Arizona Regulatory Branch
3636 N. Central Ave., Suite
900
Phoenix, AZ 85012-1939
602-230-6949 (General)
splregulatoryaz@usace.army
.mil
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52. Flood Control District of Maricopa County
MISSION: Reduce county resident’s risks of injury,
death, and property damage due to flooding
Major Activities
o Floodplain & Watershed Studies
o Floodplain Regulation
o Flood Hazard Mitigation
• Structural
• Non-structural
o Operations & Maintenance
• Dams, channels, levees, and basins
54. Alluvial Fan Characteristics in
Maricopa County
Low Slopes
Water Flood
Dominated
Distal From Mountain
Front
Limited Aerial Extent
(small)
Relatively Small Peaks
(high Q/area)
Low Flood Volumes
(flashy)
Transitions to Sheet
Flow
57. Hayden & Pinnacle Peak 1993 & 2013
North Scottsdale
TP will insert 2
photos
58.
59. Need for Solutions for Rawhide Wash
• Largest Flood Hazard in
Study Area
• High risks to people and
properties
• Feasible solutions that
could:
• Mitigate the hazards
• Reduce the risks
• Benefits > Costs
61. Rawhide Wash Flood Hazards
• High Flows (9600 cfs)
• Active Alluvial Fan
o Flow paths can change
o High uncertainty
o Structural solution is required
to:
- Mitigate the flood hazard
- Revise the floodplain maps
(FEMA)
Add Photo of
Rawhide
Apex
62. Why is Rawhide Wash Hazardous?
Active Alluvial Fan = Wash is Unpredictable
63. Rawhide Wash:
Floodplain & Regulatory Aspects
1. Flood insurance required (mortgaged houses)
• Approximately 4,000 properties in floodplain
• Flood insurance premiums
o Annually $1.6 Million
o Over 50-year period estimate $155 Million
2. Development requirements
• Elevate houses
• Construct infrastructure to address Rawhide Wash flows
64. 1. Mitigate the Alluvial Fan Flood
Hazard
• Ensure flow path certainty
• Control sediment
2. Reduce the floodplain
• Revise from AO to AE
• Removes >2,000 acres from the
floodplain
3. Facilitate Economic Development
• More land to develop
• Less expensive to develop
Rawhide Wash Goals:
65. No Action Alternative
• Accept the risk
• 4,000 properties remain in
floodplain
• High costs to Future and
Existing Property Owners
– Flood Damages
– Flood Insurance
– Development Costs
66. NO ACTION
• 6500 acres/4000 properties
remain in floodplain
• 500 structures at high
potential flood risk
• High costs to Property Owners
– Flood Insurance
– Existing & Future
– Development Costs
• Cost Estimate: $224 Million
67. BUILD
• Build structures to reduce the risk
& size of floodplain
– Addresses uncertainty
– Levee, floodwalls, basin, and grade
control structures
– Floodplain would be remapped to
remove floodplain for about 3,400
properties/3000 acres
• Moderate costs
– Cities & County
– Future Developers
68. Flood Control Mitigation Solutions
Two Options: Convey or Detain Flood Water
• Conveyance
o Natural Washes
o Channels
o Levees
o Storm Drains
o Flood walls
Note: Bold and underlined are the options being considered for Rawhide
69. Flood Control Mitigation Solutions
Two Options: Convey or Detain Flood Water
• Detention
o Basins
o In-line
o Off-line
o Dams
Note: Bold and underlined are the options being considered for Rawhide
Street view of basin above
In-line Detention Basin
70. Basin to Reduce Flow
• Considering two potential
general locations
• Offline basin
o Low or frequent flows
remain in wash to sustain
vegetation
o Flood flows go into basin
Jomax Road
Happy Valley
Road
Pima
Road
71. Basin to Reduce Flow
• Flows would be less than
the current peak
discharge of 9,600 cfs
• Flows contained between
levees and floodwalls
o Fewer levees may be
needed
o Fewer walls may need to
be reconstructed
Joax Road
Happy Valley
Road
Pima
Road
74. Recommendation Development
. Collaborative process
Continuous input on how
problems are fixed
• Identify potential solutions
o Non-structural
o Structural
o Floodplain redelineations
Acceptable
Fiscally
Responsible
Compatible
75. Developing Safety on Alluvial
Fans
Few trees in
area are gone
January 19, 1997
Location of bank
January 2, 1964
Deepen foundation
footings
Elevate structures
