HomeMy WebLinkAboutLetter from FEMA - Levee status 8-12-09 U.S.Department of[homeland Security
I I I I Broadway,Suitt 1200
oEvrr Rt Oakland,CA.94607-4052
FEMA0
August 12,2009 130AIJo 01Z.SUPEF?V1S0RS
Mr.Bill Connelly,Chairman Yr I Ij 2009
Btt Lower Wyandotte Board ando f Supervisors OROVILLS, CALIFORIVIA
Oroville,CA 95966
Dear Chairman Connelly:
This letter confirms the Provisionally Accredited Levee(PAL)status requested by
correspondence from Stuart Edell,Manager,Butte County Land Development Division,dated
June 18,2009 for the levees listed below.These levees are also identified on the enclosed Levee
Status table.
• Levees with ID#s 1244, 1256, 1278, 1173, 1164, 1243, 1160, 1034 and 1297 along the
Chico&Mud Creek&Sandy Gulch Flood Control Project.
The flood hazard information presented on the effective Flood Insurance Rate Map(FIRM)and in
the effective Flood Insurance Study(FIS)report for Butte County,California is based,in some
areas,on flood protection provided by these levees. Based on the information available and on the
mapping standards of the National Flood Insurance Program(NFIP)at the time that the FIS was
performed,FEMA accredited the levees with providing protection from the flood that has a
1-percent-chance of being equaled or exceeded in any given year. This 1-perccnt-annual-chance
flood is referred to as the base flood.
The Department of Homeland Security's,Federal Emergency Management Agency(FEMA)is
currently in the process of producing a countywide FIS report and Digital Flood Insurance Rate
Map(DFIRM)for Butte County,California. Providing communities with up-to-date,accurate,and
reliable flood Hazard information on DFIRMs is one of the primary goals of FEMA's Map
Modernization program. As part of this process,FEMA sent you a letter dated October 29,2008,to
provide you the opportunity to receive a Provisionally Accredited Levee(PAL)designation for
these levees. FEMA has received your signed PAL agreement dated June 17,2009. A copy of that
PAL agreement is enclosed Please note that levee ID#1316 was deleted from the PAL agreement
since it was not eligible for a PAL and that adjustment was coordinated with Stuart Edell. Based on
your response,your signed PAL agreement,with that modification,is acceptable.
The 2-year PAL period for these levees started on January 27,2009. FEMA will designate these
levees as PALS on the new countywide DFIRM for Butte County during the 2-year PAL period to
convey to map users that formal levee certification verification is underway.FEMA recommends
that levee owners and community officials undertake outreach efforts to inform affected property
owners that this verification process is underway.FEMA also encourages the purchase of flood
insurance for the area landward of the levees,even though coverage is not federally required.
All the necessary documentation to show that these levees meet the criteria of the Code of Federal
Regulations,Title 44, Section 65.10(44 CFR 65.10)must be provided by the end of the 2-year PAL
cc 1305I �.
August 12,2009
Mr.Bill Connelly,Chairman
Page 2 of 2
period. If you are unable to submit documentation by this deadline or if the submitted
documentation is determined to be inadequate,FEMA will initiate a map revision to re-designate
certain areas on the landward side of the levees as floodprone. Certification by a Registered
Professional Engineer must accompany the submitted 44 CFR 65.10 data.As an alternative,
USACE may also certify that the levee has been adequately designed and constructed to provide
protection against the base flood. You must submit a progress report to FEMA within 1 year of the
start of the 2-year PAL period to document progress toward obtaining data and documentation to
comply with 44 CFR 65.10.
Key milestones and dates are provided in the table below.
Date Milestone
10/29/2009 Date of FEMA PAL offer letter
6/17/2009 Date that community/levee owner signed the PAL A reement
6/20/2009 Date that FEMA received the signed PAL Agreement
1/27/2009 Start date of 2-year PAL period
1/27/2010 rl-year deadline for submitting pmgress report to FEMA
1/27/2011
2-year deadline for submitting all 44 CFR 65.10 data to FEMA
If you have questions or need additional information regarding flood mapping,please contact
Kathy Schaefer,Regional Engineer,by telephone at(510)627-7129
Sincerely,
Sally Ziolkowsla,Director
Mitigation Division
Enclosures:
■ Requirements of 44 CFR Section 65.10:Mapping of Areas Protected by Levee Systems
■ Signed PAL agreement
■ Levee Status table
cc: Kathleen Moghannam,Assistant Clerk of the Board of Supervisors
Honorable Ann Schwab,Mayor,City of Chico
David Burkland,City Manager,City of Chico
Stuart Edell,Manager,Land Development Div.&Floodplain Administrator,Butte County
Mike Crump,Butte Co.Director of Public Works
Ricardo Pineda,CA NFIP State Coordinator
Judy Souticre,USAGE, Sacramento District
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As part of a mapping project,it is the levee owner's or community's responsibility to provide data and documentation to
show that a levee meets the requirements of Section 65.10 of the National Flood Insurance Program(NFIP)regulations.
Links to Section 65.10 and many other documents are available on FEMA's Web site at
www.fema.sav/plan/preventlfhm/ly fnrn.shtm.
The FEMA requirements in Section 65.10 are separated into five categories:
1. General criteria;
2. Design criteria;
3. Operations plans and criteria;
4. Maintenance plans and criteria;and
5. Certification requirements.
The requirements for each of these areas are summarized below.
(A) GENERAL CRITERIA
For purposes of the NFIP,FEMA will only recognize in its flood hazard and risk mapping effort those levee systems that
meet,and continue to meet,minimum design,operation,and maintenance standards that are consistent with the level of
protection sought through the comprehensive floodplain management criteria established by Section 60.3 of the NFIP
regulations. Section 65.10 of the NFIP regulations describes the types of information FEMA needs to recognize,on NFIP
maps,that a levee system provides protection from the flood that has a 1-percent chance of being equaled or exceeded in
any give year(base flood). This information must be supplied to FEMA by the community or other party seeking
recognition of a levee system at the time a study or restudy is conducted,when a map revision under the provisions of Part
65 of the NFIP regulations is sought based on a levee system,and upon request by the Administrator during the review of
previously recognized structures. The FEMA review is for the sole purpose of establishing appropriate risk zone
determinations for NFIP maps and does not constitute a determination by FEMA as to how a structure or system will
perform in a flood event.
(B) DESIGN CRITERIA
For the purposes of the NFIP,FEMA has established levee design criteria for freeboard,closures,embankment protection,
embankment and foundation stability,settlement,interior drainage,and other design criteria. These criteria are
summarized in subsections below.
(B)(1) FREEBOARD
For riverine levees:
• A minimum freeboard of 3 feet above the water-surface level of the base flood must be provided.
• An additional 1 foot above the minimum is required within 100 feet on either side of structures(e.g.,bridges)
river-ward of the levee or wherever the flow is constricted.
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• An additional 0.5 foot above the minimum at the upstream end of the levee,tapering to not less than the minimum
at the downstream end of the levee,is also required.
Exceptions to the minimum riverine freeboard requirements above may be approved if the following criteria are met:
• Appropriate engineering analyses demonstrating adequate protection with a lesser freeboard must be
submitted.
• The material presented must evaluate the uncertainty in the estimated base flood elevation profile and include,
but not necessarily be limited to:
o An assessment of statistical confidence limits of the I-percent-annual-chance discharge;
o Changes in stage-discharge relationships;and
o Sources,potential,and magnitude of debris,sediment,and ice accumulation.
• It must be also shown that the levee will remain structurally stable during the base flood when such additional
loading considerations are imposed.
Under no circumstances will freeboard of less than 2 feet be accepted.
For coastal levees,the freeboard must be established at 1 foot above the height of the 1-percent-annual-chance wave or
the maximum wave runup(whichever is greater)associated with the I-percent-annual-chance stillwater surge elevation at
the site.
Exceptions to the minimum coastal freeboard requirements above may be approved if the following criteria are met:
• Appropriate engineering analyses demonstrating adequate protection with a lesser freeboard must be
submitted.
• The material presented must evaluate the uncertainty in the estimated base flood loading conditions.
Particular emphasis must be placed on the effects of wave attack and overtopping on the stability of the levee.
Under no circumstances will a freeboard of less than 2 feet above the 1-percent-annual-chance stillwater surge elevation
be accepted.
(B)(2) CLOSURES
The levee closure requirement is that all openings must be provided with closure devices that are structural parts of the
system during operation and design according to sound engineering practice.
(B)(3) EMBANKMENT PROTECTION
Engineering analyses must be submitted to demonstrate that no appreciable erosion of the levee embankment can be
expected during the base flood,as a result of either currents or waves,and that anticipated erosion will not result in failure
of the levee embankment or foundation directly or indirectly through reduction of the seepage path and subsequent
instability.
The factors to be addressed in such analyses include,but are not limited to:
• Expected flow velocities(especially in constricted areas);
• Expected wind and wave action;
March 2007 PAGE 2
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• Ice loading;
• Impact of debris;
• Slope protection techniques;
• Duration of flooding at various stages and velocities;
• Embankment and foundation materials;
• Levee alignment,bends,and transitions;and
• Levee side slopes.
(11)(4) EMBANKMENT AND FOUNDATION STABILITY
Engineering analyses that evaluate levee embankment stability must be submitted.
The analyses provided shall evaluate expected seepage during loading conditions associated with the base flood and shall
demonstrate that seepage into or through the levee foundation and embankment will not jeopardize embankment or
foundation stability.
An alternative analysis demonstrating that the levee is designed and constructed for stability against loading conditions for
Case IV as defined in U.S.Army Corps of Engineers(USACE)Engineering Manual 1110-2-1913,Chapter 6,Section II,
may be used.
The factors that shall be addressed in the analyses include:
• Depth of flooding;
• Duration of flooding;
• Embankment geometry and length of seepage path at critical locations;
• Embankment and foundation materials;
• Embankment compaction;
• Penetrations;
• Other design factors affecting seepage(e.g.,drainage layers);and
• Other design factors affecting embankment and foundation stability(e.g.,berms).
(11)(5) SETTLEMENT
Engineering analyses must be submitted that assess the potential and magnitude of future losses of freeboard as a result of
levee settlement and demonstrate that freeboard will be maintained within the minimum freeboard standards set forth in
B(1).
This analysis must address:
• Embankment loads,
• Compressibility of embankment soils,
• Compressibility of foundation soils,
March 2007 PAGE 3
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• Age of the levee system,and
• Construction compaction methods.
A detailed settlement analysis using procedures such as those described in USACE Engineering Manual EM 1100-2-1904
must be submitted.
(13)(6) INTERIOR DRAINAGE
An analysis must be submitted that identifies the source(s)of such flooding;the extent of the flooded area;and,if the
average depth is greater than 1 foot,the water-surface elevation(s)of the base flood. This analysis must be based on the
joint probability of interior and exterior flooding and the capacity of facilities(such as drainage Iines and pumps)for
evacuating interior floodwaters. Interior drainage systems usually include storage areas,gravity outlets,pumping stations,
or a combination thereof.
For areas of interior drainage that have average depths greater than 1 foot,mapping must be provided depicting the
extents of the interior flooding,along with supporting documentation.
(B)(7) OTHER DESIGN CRITERIA
In unique situations,such as those where the levee system has relatively high vulnerability,FEMA may require that other
design criteria and analyses be submitted to show that the levees provide adequate protection. In such situations,sound
engineering practice will be the standard on which FEMA will base its determinations. FEMA also will provide the
rationale for requiring this additional information.
(C) OPERATIONS PLANS AND CRITERIA
For a levee system to be recognized,the operational criteria must be as described below. All closure devices or
mechanical systems for internal drainage,whether manual or automatic,must be operated in accordance with an officially
adopted operation manual,a copy of which must be provided to FEMA by the operator when levee or drainage system
recognition is being sought or when the manual for a previously recognized system is revised in any manner. All
operations must be under the jurisdiction of a Federal or State agency,an agency created by Federal or State law,or an
agency of a community participating in the NFIP.
(C)(I) CLOSURES
Operation plans for closures must include the following:
• Documentation of the flood wanting system,under the jurisdiction of Federal, State,or community officials,that
will be used to trigger emergency operation activities and demonstration that sufficient flood warning time exists
for the completed operation of all closure structures,including necessary sealing,before floodwaters reach the
base of the closure;
• A formal plan of operation,including specific actions and assignments of responsibility by individual name or
title;and
• Provisions for periodic operation,at not less than 1-year intervals,of the closure structure(s)for testing and
training purposes.
March 2007 PAGE 4
(C)(2) INTERIOR DRAINAGE SYSTEMS
Interior drainage systems associated with levee systems usually include storage areas,gravity outlets,pumping stations,or
a combination thereof. FEMA will recognize these drainage systems on NFIP maps for flood protection purposes only if
the following minimum criteria are included in the operation plan:
• Documentation of the flood warning system,under the jurisdiction of Federal,State,or community officials,that
will be used to trigger emergency operation activities and demonstration that sufficient flood warning time exists
to permit activation of mechanized portions of the drainage system;
• A formal plan of operation,including specific actions and assignments of responsibility by individual name or
title;
• Provision for manual backup for the activation of automatic systems;and
• Provisions for periodic inspection of interior drainage systems and periodic operation of any mechanized portions
for testing and training purposes;no more than I year shall elapse between either the inspections or the
operations.
(C)(3) OTHER OPERATION PLANS AND CRITERIA
FEMA may require other operating plans and criteria to ensure that adequate protection is provided in specific situations.
In such cases,sound emergency management practice will be the standard upon which FEMA determinations will be
based.
(D) MAINTENANCE PLANS AND CRITERIA
For levee systems to be recognized as providing protection from the base flood,the following maintenance criteria must
be met:
• Levee systems must be maintained in accordance with an officially adopted maintenance plan,and a copy of this
plan must be provided to FEMA by the owner of the levee system when recognition is being sought or when the
plan for a previously recognized system is revised in any manner.
• All maintenance activities must be under the jurisdiction of a(n):
o Federal or State agency;
o Agency created by Federal or State law; or
o Agency of a community participating in the NFIP that must assume ultimate responsibility for
maintenance.
• The maintenance plan must document the formal procedure that ensures that the stability,height,and overall
integrity of the levee and its associated structures and systems are maintained:
• At a minimum,the maintenance plan shall specify:
o Maintenance activities to be performed;
o Frequency of their performance;and
o Person by name or title responsible for their performance.
March 2007 PAGE 5
(E) CERTIFICATION REQUIREMENTS
Data submitted to support that a given levee system complies with the structural requirements set forth in B(1)through
B(7)above must be certified by a Registered Professional Engineer. Also,certified as-built plans of the levee must be
submitted. Certifications are subject to the definition given in Section 65.2 of the NFIP regulations. In lieu of these
structural requirements,a Federal agency with responsibility for levee design may certify that the levee has been
adequately designed and constructed to provide protection against the base flood.
March 2007 PAGE 6
Letter of Agreement and Request for Provisionally Accredited Levee(PAL)Designation and Agreement to
Provide Adequate Compliance with the Code of Federal Regulations,Title 44,Section 65.10(44 CFR 65.10)
PAL Aareement Form for Butte County,California
We,the undersigned,have received a letter from FEMA dated October 28, 2008 with an enclosed "Levee Status
Map"and "Levee Status Table"and two enclosed documents titled "Title 44 of the Code of Federal Regulations
(CFR), Section 65.10(44 CFR 65.10)"and"Requirements of 44 CFR Section 65.10:Mapping of Areas Protected
by Levee Systems."We understand that FEMA is in the process of providing an updated Flood Insurance Rate Map
for Butte County California and that the flood hazards around levee(s)identified on the Levee Status Map and
Levee Status Table with unique levee 1D numbers 1244, 1256, 1278, 1173, 1164, 1243, 1160, 1034, 1316 &
1297, will be rernapped to reflect that these levees have been designated a PAL.These levees are also known as the
levees constructed by the Corps of Engineers in their project entitled, "CHICO&MUD CREEK&SANDY
GULCH FLOOD CONTROL PROJECTT",from the Big Chico Creek diversion to the Union Pacific railroad.
To the best of our knowledge,the levees identified above meet the criteria of 44 CFR 65.10 and have been
maintained in accordance with an adopted operation and maintenance plan.For.Scenario A(non-USACE Program)
levees,this must be evidenced by an attached Operation and Maintenance flan and records of levee maintenance
and operation,as well as Test Records of Mechanized Interior Drainage System. We hereby submit to FEMA
within 90 days of the date set forth below our agreement to provide FEMA with all the necessary information to
show that the applicable Ievees identified above comply with 44 CFR 65.10. We understand that this
documentation will be provided before 90 days of the date set forth below. Providing the information described in
44 CFR 65.10 will allow FEMA to move forward with the flood mapping for Butte County. We fully understand
that if complete documentation of compliance with 44 CFR 65.10 is not provided within the designated time frame
of 24 months,FEMA will initiate a revision to the Flood Insurance Rate Map for Butte County to redesignate the
area as flood prone.
Levee Owner Representative(signature): Date:
Levee Owner Representative(print name):
Levee Owner Title/Organization (print):
Community CEO(signature): Date:
Community CEO(print name): Gregory G.Iturria
Community Name(print). Butte County
City of Chico(signature): Date:
City of Chico(print name):
Required Attachments for Scenario A anon-USACE Program)Levees only:
• Operation and Maintenance Plan and Records
■ Test Records of Mechanized Interior Drainage System
Provisionally Accredited Levee(PAL)Agreement Form 1 of 1
ATTACHMENT B