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Thread: [IowaAPA] FEMA DFIRM -- New A Zones

  1. #1
    Laura Carstens
    Guest

    [IowaAPA] FEMA DFIRM -- New A Zones

    The City of Dubuque has received a draft Digital Flood Insurance Rate Map (DFIRM) from FEMA that includes several new A zones.

    The new DFIRM significantly expands the number of properties designated as being in a flood plain in the city limits. There are approximately 70 structures in the current flood zones. The proposed new A zones would include approximately 1,806 properties, with an estimated 1,741 structures.

    We are interested to learn if any other cities or counties in Iowa are encountering similar changes in their DFIRMs with respect to new, substantial A zones.

    If your DFIRM did not change, we'd like to know that, too.

    We look forward to hearing from you. Thanks!

    Laura Carstens




    Laura Carstens
    Planning Services Manager
    50 W. 13th Street
    Dubuque IA 52001
    Phone: 563-589-4210
    Fax: 563-589-4221

  2. #2
    Burke, Bill
    Guest

    RE: [IowaAPA] FEMA DFIRM -- New A Zones

    The same thing (errors) occurred on the Lansing FEMA maps. In this case, the FEMA consultant I talked with acknowledged using 1960's era 20 foot contour mapping-no wonder.
    Also, I have found several such map differences in communities in Wisconsin which I work with.
    Bill Burke AICP

    From: IowaAPA (AT) yahoogroups (DOT) com [mailto:IowaAPA (AT) yahoogroups (DOT) com] On Behalf Of Laura Carstens
    Sent: Tuesday, November 03, 2009 10:52 AM
    To: IowaAPA (AT) yahoogroups (DOT) com
    Subject: [IowaAPA] FEMA DFIRM -- New A Zones

    The City of Dubuque has received a draft Digital Flood Insurance Rate Map (DFIRM) from FEMA that includes several new A zones.

    The new DFIRM significantly expands the number of properties designated as being in a flood plain in the city limits. There are approximately 70 structures in the current flood zones. The proposed new A zones would include approximately 1,806 properties, with an estimated 1,741 structures.

    We are interested to learn if any other cities or counties in Iowa are encountering similar changes in their DFIRMs with respect to new, substantial A zones.

    If your DFIRM did not change, we'd like to know that, too.

    We look forward to hearing from you. Thanks!

    Laura Carstens



    [cid:image001.jpg (AT) 01CA5C7F (DOT) 484B5920]
    Laura Carstens
    Planning Services Manager
    50 W. 13th Street
    Dubuque IA 52001
    Phone: 563-589-4210
    Fax: 563-589-4221

  3. #3
    The City of Newton (IA) had the same experience. They took former Zone B areas, expanded them and then made them Zone A. There was one area in particular that they were so far-off that we were eventually able to get them to pull the zone back. It was a very frustrating process with eventually led to the involvement of some politicians.

    Newton did not have a BFE completed for the City. The FEMA consultants/technicians doing the DFIRM were using topography maps and aerial photographs to make their determination. In this one particular location, if a site visit had been completed, it would have been quite clear that the need for the very large designated zone was not necessary. Unfortunately, a site visit on the part of FEMA or their contractor was never completed.


    If you are interested, I would be glad to scan some of the correspondence between the City and FEMA for you to take a look at. Feel free to email me at erinc@newtongov.org if you have any questions.

    Erin R. Chambers, AICP
    City Planner, City of Newton
    1700 N 4th Ave W
    Newton, Iowa 50208
    641-792-6622
    erinc@newtongov.org

  4. #4
    Laura Carstens
    Guest

    RE: [IowaAPA] FEMA DFIRM -- New A Zones

    Thanks, Bill.

    >>> "Burke, Bill" <bburke (AT) davyinc (DOT) com> 11/3/2009 12:15 PM >>>

    The same thing (errors) occurred on the Lansing FEMA maps. In this case, the FEMA consultant I talked with acknowledged using 1960's era 20 foot contour mapping-no wonder.
    Also, I have found several such map differences in communities in Wisconsin which I work with.
    Bill Burke AICP

    From: IowaAPA (AT) yahoogroups (DOT) com [mailto:IowaAPA (AT) yahoogroups (DOT) com] On Behalf Of Laura Carstens
    Sent: Tuesday, November 03, 2009 10:52 AM
    To: IowaAPA (AT) yahoogroups (DOT) com
    Subject: [IowaAPA] FEMA DFIRM -- New A Zones

    The City of Dubuque has received a draft Digital Flood Insurance Rate Map (DFIRM) from FEMA that includes several new A zones.

    The new DFIRM significantly expands the number of properties designated as being in a flood plain in the city limits. There are approximately 70 structures in the current flood zones. The proposed new A zones would include approximately 1,806 properties, with an estimated 1,741 structures.

    We are interested to learn if any other cities or counties in Iowa are encountering similar changes in their DFIRMs with respect to new, substantial A zones.

    If your DFIRM did not change, we'd like to know that, too.

    We look forward to hearing from you. Thanks!

    Laura Carstens




    Laura Carstens
    Planning Services Manager
    50 W. 13th Street
    Dubuque IA 52001
    Phone: 563-589-4210
    Fax: 563-589-4221

  5. #5
    Cyburbian The One's avatar
    Registered
    Mar 2004
    Location
    Where Valley Fever Lives
    Posts
    7,146

    Hmmm.....

    I'm not in Iowa, but......

    Are the newly shown Zone A's being converted from previous shaded zone x areas? If so, were these previous shaded zone x areas in place due to provisionally accredited levees? Are the levees now being decertified (like those along the Colorado River)?

    I think the biggest problem area in Western Arizona with similar issues is near the community of San Luis. 1,000's of homes in a shaded zone x that may now be within a zone A or D after Colorado Levees are decertified. I just checked and their PAL agreement with FEMA is set to expire in 16 days having two+ years of notice helped provide the residents with the time needed to buy the lower priced insurance policies and to be considered as pre-existing policy holders.
    Skilled Adoxographer

  6. #6
    Laura Carstens
    Guest

    Re: [IowaAPA] FEMA DFIRM -- New A Zones

    The largest of the new A zones, impacting 1,400 properties, has never been on a FIRM in any kind of zone.

    We have a levee/floodwall system along our Mississippi Riverfront that we are in the process of certifying with the help of the U.S. Army Corps of Engineers in accordance with our PAL with FEMA. The levee provides Zone X coverage for a large portion of our downtown, industrial waterfront areas, and commercial recreational areas.



    Laura Carstens
    Planning Services Manager
    50 W. 13th Street
    Dubuque IA 52001
    Phone: 563-589-4210
    Fax: 563-589-4221


    >>> Cyburbia Forums Gateway <gateway.iowaapa (AT) cyburbia (DOT) org> 11/3/2009 3:47 PM >>>


    I'm not in Iowa, but......

    Are the newly shown Zone A's being converted from previous shaded zone
    x areas? If so, were these previous shaded zone x areas in place due to
    provisionally accredited levees? Are the levees now being decertified
    (like those along the Colorado River)?

    I think the biggest problem area in Western Arizona with similar issues
    is near the community of San Luis. 1,000's of homes in a shaded zone x
    that may now be within a zone A or D after Colorado Levees are
    decertified. I just checked and their PAL agreement with FEMA is set to
    expire in 16 days having two+ years of notice helped provide the
    residents with the time needed to buy the lower priced insurance
    policies and to be considered as pre-existing policy holders.


    --
    The One

    Stephen King's inspiration:
    While browsing through an attic with his elder brother, King uncovered
    a paperback version of an *H. P. Lovecraft *collection of short stories
    that had belonged to his father. The cover art-an illustration of a
    monster hiding within the recesses of a hell-like cavern beneath a
    tombstone-was, he writes, "the moment of my life when the dowsing rod
    suddenly went down hard ... as far as I was concerned, I was on my way."
    ------------------------------------------------------------------------
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  7. #7
    Cyburbian The One's avatar
    Registered
    Mar 2004
    Location
    Where Valley Fever Lives
    Posts
    7,146

    Ok...

    Assuming the levee certification is successful, the previously shaded zone x should remain a zone x for the area protected by the now certified levee and depicted as such on the new maps. If the levee certification is unsuccessful, the previously shaded zone X area could be shown as Zone D or A on the new maps.

    A truly new zone A area not associated with the levee system may be related to some other flood consideration.

    Are the maps showing new Zone A areas labeled as preliminary DFIRMS for your jurisdictional review and comment?
    Skilled Adoxographer

  8. #8
    Paul Dekker
    Guest

    RE: [IowaAPA] FEMA DFIRM -- New A Zones

    The City of Urbandale has a similar experience with the draft DFIRM
    issued in June (still "pending"). Existing Zone A's were impacted by
    substituting "new" topographic information with 10-foot contour
    intervals (I think) for the City's old, but 2-foot contour maps that had
    been utilized by FEMA for all prior FIRMS and which continues to be used
    for one waterway with a detailed study.

    Engineering consultants retained by the City in the early 1980's used
    the same topographic information, supplemented by field measurements of
    culverts and limited cross-sections, to largely affirm the Zone A
    boundaries of the FEMA maps.

    The "new" topo used by FEMA's consultant on the DFIRM, because of its
    far less-precise contour interval, takes in substantially more
    structures and some additional properties-not because of better flood
    studies or information substantiating flood risks that hadn't previously
    been identified, but because of less precise mapping. The DFRIM has
    MUCH better horizontal control, given that the old FIRM's had none, but
    it's "false accuracy".

    There was also one new Zone A established that takes in numerous
    properties, that hadn't previously been identified. It's reasonable
    that the Zone A was identified, since its basin is equal to that of
    other Zone A's, BUT it also utilized imprecise topo information that
    grossly overstates the flood hazard. The area was developed with
    engineered channels sized to carry the 1% storm, but the Zone A was
    established as if everything had remained pre-development in terms of
    the stream, but post-development in terms of runoff (and disregarding
    storm detention).

    Within detailed study areas, there is some imprecise mapping because the
    "hard copy" boundaries were overlaid on the DFIRM without any "rubber
    sheeting" to account for discrepancies between the accurate horizontal
    scaling of the DFIRM and very imprecise scale of the "hard copy" FIRM.
    (The old FIRM's are not only at a very small scale, but imprecisely
    drawn so that map-scaled dimensions between fixed points deviate by 10%
    or more from actual, verifiable dimensions. The DFIRM's are close to
    the actual, verifiable dimensions BUT when the old "hard copy" zone
    boundaries were overlaid onto the DFIRM they weren't adjusted to account
    for the DFIRM's change in horizontal accuracy, to maintain the same
    relationship between zone boundary and fixed points that existed on the
    FIRM.) Optimally, accurate topography would have been used instead of
    overlaying the old zone boundaries at all, so flood limits wouldn't run
    uphill, etc. but if the old lines HAD to be used they should at least
    have been adjusted.

    Urbandale wasn't allowed to "object" since no new Base Flood Elevations
    were issued for the community, and was therefore limited to "comment".
    "Comment" were filed per the above in July (use the City's 2-foot
    contours/engineering studies in lieu of the 10-foot contours etc), with
    no response received to date.

    Optimally, the State's LiDAR would be used to the maximum extent
    possible, which would VASTLY improve the DFIRM over anything prior, even
    without any new studies, in my opinion....



    Paul Dekker



    Director of Community Development

    3600 86th Street

    City of Urbandale, IA 50322-4057



    515-331-6721

    515-278-3927 (Fax)

    PDekker (AT) Urbandale (DOT) org

    http://www.urbandale.org/



    ________________________________

    From: IowaAPA (AT) yahoogroups (DOT) com [mailto:IowaAPA (AT) yahoogroups (DOT) com] On Behalf
    Of Laura Carstens
    Sent: Tuesday, November 03, 2009 10:52 AM
    To: IowaAPA (AT) yahoogroups (DOT) com
    Subject: [IowaAPA] FEMA DFIRM -- New A Zones



    The City of Dubuque has received a draft Digital Flood Insurance Rate
    Map (DFIRM) from FEMA that includes several new A zones.



    The new DFIRM significantly expands the number of properties designated
    as being in a flood plain in the city limits. There are approximately
    70 structures in the current flood zones. The proposed new A zones
    would include approximately 1,806 properties, with an estimated 1,741
    structures.



    We are interested to learn if any other cities or counties in Iowa are
    encountering similar changes in their DFIRMs with respect to new,
    substantial A zones.



    If your DFIRM did not change, we'd like to know that, too.



    We look forward to hearing from you. Thanks!



    Laura Carstens









    Laura Carstens

    Planning Services Manager

    50 W. 13th Street

    Dubuque IA 52001

    Phone: 563-589-4210

    Fax: 563-589-4221

  9. #9
    Laura Carstens
    Guest

    Re: [IowaAPA] FEMA DFIRM -- New A Zones

    Yes, the Zone X will remain as a protected area.

    Yes, the maps showing new Zone A areas are labeled as preliminary DFIRMS for
    your jurisdictional review and comment.





    Laura Carstens
    Planning Services Manager
    50 W. 13th Street
    Dubuque IA 52001
    Phone: 563-589-4210
    Fax: 563-589-4221


    >>> Cyburbia Forums Gateway <gateway.iowaapa (AT) cyburbia (DOT) org> 11/3/2009 5:22 PM >>>


    Assuming the levee certification is successful, the previously shaded
    zone x should remain a zone x for the area protected by the now
    certified levee and depicted as such on the new maps. If the levee
    certification is unsuccessful, the previously shaded zone X area could
    be shown as Zone D or A on the new maps.

    A truly new zone A area not associated with the levee system may be
    related to some other flood consideration.

    Are the maps showing new Zone A areas labeled as preliminary DFIRMS for
    your jurisdictional review and comment?


    --
    The One

    Stephen King's inspiration:
    While browsing through an attic with his elder brother, King uncovered
    a paperback version of an *H. P. Lovecraft *collection of short stories
    that had belonged to his father. The cover art-an illustration of a
    monster hiding within the recesses of a hell-like cavern beneath a
    tombstone-was, he writes, "the moment of my life when the dowsing rod
    suddenly went down hard ... as far as I was concerned, I was on my way."
    ------------------------------------------------------------------------
    The One's Profile: http://www.cyburbia.org/forums/member.php1989
    View this thread: http://www.cyburbia.org/forums/showthread.php?t=39281



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  10. #10
    Cyburbian Queen B's avatar
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    I am not in Iowa either but the City of Salina, KS is experiencing the same thing. They have a significant number of homes being put in the Zone A. If they don't get levy accredidation then almost the entire city proper will be in.


    Being the good CFM that I am, I checked to make sure we were out of the floodplain. But alas in the new maps we are in. We have done some extensive "landscaping" and intend to file a LOMA as soon as the new maps are adopted.
    It is all a matter of perspective!!!

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