HomeMy WebLinkAboutFDP201700008 Correspondence 2019-07-03NATIONAL FLOOD INSURANCE PROGRAM
FEMA PRODUCTION AND TECHNICAL SERVICES CONTRACTOR
Ms. Carolyn A. Howard, P.E.
Draper Aden Associates
2206 South Main Street
Blacksburg, VA 24060
Dear Ms. Howard:
July 3, 2019
IN REPLY REFER TO:
Case No.: 19-03-1243P
Communities: Independent City of Charlottesville
and Unincorporated Areas of
Albemarle County, VA
Community Nos.: 510033 and 510006
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This responds to your request dated May 30, 2019, that the Department of Homeland Security's Federal
Emergency Management Agency (FEMA) issue a revision to the Flood Insurance Rate Map (FIRM) for
Albemarle County, Virginia, and Incorporated Areas and the Independent City of Charlottesville, Virginia.
Pertinent information about the request is listed below.
Identifier: Meadow Creek
Flooding Source: Meadow Creek
FIRM Panels Affected: 51003CO278D and 51003CO286D
The data required to complete our review, which must be submitted within 90 days of the date of this letter,
are listed on the attached summary.
If we do not receive the required data within 90 days, we will suspend our processing of your request.
Any data submitted after 90 days will be treated as an original submittal.
FEMA receives a very large volume of requests and cannot maintain inactive requests for an indefinite period
of time. Therefore, we are unable to grant extensions for the submission of required data for revision requests.
If a requester is informed by letter that additional data are required to complete our review of a request, the
data must be submitted within 90 days of the date of this letter.
LOMC Clearinghouse, 3601 Eisenhower Avenue, Suite 500, Alexandria, VA 22304-6426 / PH: 1-877-FEMA MAP
Compass, under contract with the Federal Emergency Management Agency, is a Production
and Technical Services provider for the National Flood Insurance Program
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If you have general questions about your request, FEMA policy, or the National Flood Insurance Program,
please contact the FEMA Map Information eXchange (FMIX), toll free, at 1-877-FEMA MAP
(1-877-336-2627). If you have specific questions concerning your request, please contact your case reviewer,
Ms. Ekta Amar, P.E., CFM, by e-mail at eamar@leonardjackson.net or by telephone at (231) 408-8046, or
the Revisions Coordinator for your state, Ms. Ellie Pitney, by e-mail at pitneyej@cdmsmith.com or by
telephone at (303) 383-2318.
Sincerely,
Benjamin Kaiser, P.E., CFM
Revisions Manager
Compass PTS JV
Attachment:
Summary of Additional Data
cc: Mr. Antony W. Edwards, CFM
N.D.S. Manager
City of Charlottesville
Mr. Frank V. Pohl, P.E., CFM
Engineer, Albemarle County
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Case No.: 19-03-1243P
NATIONAL FLOOD INSURANCE PROGRAM
FEMA PRODUCTION AND TECHNICAL SERVICES CONTRACTOR
Case No.: 19-03-1243P
Summary of Additional Data Required to Support a
Letter of Map Revision (LOMR)
Requester: Ms. Carolyn A. Howard, P.E.
Communities: Independent City of Charlottesville and Community Nos.: 510033 and 510006
Unincorporated Areas of
Albemarle County, VA
The issues listed below must be addressed before we can continue the review of your request.
1. Our review of the submitted MT-2 Form 1, entitled "Overview and Concurrence Form" revealed that
the digital signature of Mr. Frank V. Pohl, P.E., CFM, Engineer, Albemarle County is not clickable
to verify. Please provide an updated signature or digital signature that can be verified easily.
Refer to attached document.
2. Our review of the submitted existing conditions hydraulic model revealed the following issues. Please
submit a digital copy of the existing conditions model that has been revised to address the following
items.
a) Our review revealed that there are several untitled plans in the submitted hydraulic HEC-
RAS model. Please remove all extra plans and submit only the final plans to review. The
plans needed are the duplicate effective (from LOMR 16-03-1697P) and existing conditions
(corrected effective) multiple profile and floodway plans. Please remove all other plans.
Please also mention the vertical datum such as North American Vertical Datum of 1988
(NAVD 88) in the HEC-RAS description box for all the models. So noted and revised.
b) Our review revealed that the water -surface elevation (WSEL) profiles that correspond to the
10-percent-annual-chance flood and 2-percent-annual-chance floods cross each other at
Cross Sections 12.8 and 12.75. Also, there is no 2-percent-annual-chance WSEL computed
at Cross Section 12.7. In addition, the WSEL profiles that correspond to the 1-percent-
annual-chance (base) and 2-percent-annual-chance floods cross each other at Cross Section
14.8. Please revise the existing conditions model to properly reflect the WSELs for each
flood event. So noted and revised.
c) Please check the location of the bank points at Cross Section 13.05 in the hydraulic model.
They are set really far apart and seem far outside the natural channel location. Please update
the bank points as per the stream channel shown on the work map and aerial imagery.
So noted and corrected.
d) Our review revealed that floodway encroachment Method 1 was performed on the 2-percent-
annual-chance flood profile in the multiple profile run of the existing/corrected effective
model. Please remove floodway encroachments from the 2-percent-annual-chance flood
profile. All recurrence intervals in the multiple profile run should be without any floodway
encroachments. The floodway encroachment should be done for base flood profile only as
per FEMA requirements and in a separate floodway analysis plan that should model only
natural (unencroached) and encroached base profiles. So noted and corrected.
LOMC Clearinghouse, 3601 Eisenhower Avenue, Suite 500, Alexandria, VA 22304-6426 / PH: 1-877-FEMA MAP
Compass, under contract with the Federal Emergency Management Agency, is a Production
and Technical Services provider for the National Flood Insurance Program
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e) Our review revealed negative surcharges between the natural base (unencroached) and
encroached profiles at Cross Sections 13.05, 12.9, 12.85, 12.8, and 12.75 in the submitted
Attached are revised models; existing conditions floodway analysis for Meadow Creek. Please revise the floodway
please note analysis to eliminate all negative surcharges and ensure that surcharges remain between 1.0
surcharges are due to foot and 0.0 feet at each cross section. Additionally, it appears that a floodway was not
hydraulic jumps in the system. computed at Cross Sections 12.7 and 12.75. There is no floodway width showing up in the
existing conditions hydraulic model at these cross sections. Please have a look at these cross
sections and ensure that the floodway is computed properly at all the cross sections and
surcharges are within acceptable limits as mentioned above.
Attached is the revised f) The topwidth in the existing conditions hydraulic analysis at Cross Section 14.3, 337 feet,
topographic work map for does not match the approximate topwidth of 303 feet shown on the topographic work map
your review. entitled "Topographic Work Map," prepared by Draper Aden Associates, dated February
13, 2019. Please submit a revised hydraulic analysis or a revised work map as appropriate
to resolve this discrepancy. Please ensure that the revised floodway delineation at Cross
Sections 13.05, 12.9, 12.85, 12.8, 12.75, and 12.7 is also updated as per the updated
encroachment stations as asked above.
Attached is the revised g) Please update the geometry at Cross Section 14.2 in the existing conditions hydraulic model
topographic work map for as per the above -referenced work map and ensure that the base floodplain and 0.2-percent-
you r review. annual -chance floodplain topwidth on the work map is consistent with the hydraulic model.
3. The above -referenced topographic work map does not provide some of the essential information
required to complete our review of this request. The LOMR16-03-1697P, effective March 22, 2017,
Attached is the revised superseded the effective Flood Insurance Rate Map (FIRM) panel delineations for the revision area.
topographic work map Please update the effective delineations on the work map to be consistent with the effective LOMR
for your review. delineations rather than the FIRM panel dated February 4, 2005. Please use boldly colored lines for
the delineations rather shading so that features below the shading are not covered up. Revised and
effective delineations should be shown in different colors and line types to easily distinguish between
them. Also, ensure that the revised base and 0.2-percent-annual-chance floodplains and floodway
delineations graphically tie in with the effective delineations smoothly at the upstream and
downstream ends of the revision area. Please submit a revised topographic work map, certified by a
registered Professional Engineer (P.E.) that shows all applicable items listed in Section C of
Application/Certification Form 2, entitled "Riverine Hydrology & Hydraulics Form."
Enclosed is the 4. Please provide an updated digital Computer -Aided Design (CAD) drawing that reflects the updated
updated CAD file. topographic work map as asked for above. Please ensure the digital data are spatially referenced and
cite what projection (coordinate system, example: UTM/State Plane) was used, so that the data may
be used for accurate mapping.
So noted and 5. Our review of the submitted annotated FIRMs revealed that they are not submitted on the effective
revised. FIRM panels that have been updated by LOMR 16-03-1697P, effective March 22, 2017. Please
submit annotated FIRMs that are based on the effective LOMR FIRM panels and show the revised
delineations in different colors to clearly distinguish between the effective and revised delineations.
So noted. 6. The submitted draft newspaper notice received on May 30, 2019, will be reviewed after the existing
Thank you. condition hydraulic model and work map are finalized. Please do not publish the newspaper notice
until it is approved by us.
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Case No.: 19-03-1243P
Please send the required data to:
LOMC Clearinghouse
Attention: LOMR Manager
3601 Eisenhower Avenue, Suite 500
Alexandria, VA 22304-6426
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For identification purposes, please include the case number referenced above on all correspondence.
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Case No.: 19-03-1243P