FLOOD STUDYRockland County, NYFEMA REGION IIApril 13, 2011

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Agenda

Introductions and Roll Call

Objectives

Map Modernization (MapMod) Program Overview

Rockland County MapMod Update

Milestones

Questions & Feedback

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Introductions and Roll Call Local – Rockland County & Communities

New York State Department of Environmental Conservation (NYSDEC)

Floodplain Management Section Chief: William Nechamen, CFM

Environmental Engineer: Kelli Higgins-Roche, CFM

Project Engineer: Arvind Goswami, PE

Mapping Partner (NY State Subcontractor) – URS

Project Manager: John Dromsky-Reed, PE, CFM

FEMA Region IIProject Officer: Alan Springett

Communications / Outreach Support: Adie Koby

Floodplain Management and Insurance Lead: Richard Einhorn & Patricia Griggs

RSC Deputy Coordinator: Tolga Yilmaz, CFM, GISP

RSC Outreach Lead: Crystal Smith, CFM

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Objectives

Objectives

• To provide an overview of Rockland County’s flood hazard mapping project status

• To promote community engagement and enhance capability to effectively manage flood risk

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Map Modernization (MapMod) Program Overview Prior to 2003, more than 70 percent of the nation’s

flood maps were at least 10 years old. In Rockland County, with few exceptions, the communities' flood maps dated back to the 1980s

Congress appropriated funds in 2003 and directed FEMA to develop and implement the MapMod program, which:

• Created county-wide digital maps

• Utilized more current data to update maps

• Developed a new platform to convert from paper to digital format

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Rockland County MapMod Update Scope of Rockland County study

• County-wide DFIRM (64 panels), including 24 incorporated communities

• 51 miles of new detailed riverine study

• Re-delineation of 74 miles of detailed studies (Rivers & Lakes) Re-delineation: Previously identified floodplains and associated detailed flood elevations paired with

updated topographic data (LIDAR) that retains the integrity of the existing Engineering analysis

• Analysis of 33 approximate stream miles Approximate Stream: The discharges for the approximate study streams were calculated using the 2006

New York regression equations for drainage points with basins >2.0 square miles. The equations were adjusted for urbanization using the USGS/Sauer method, utilizing ortho-imagery, MRLS data, and USGS mapping. For smaller basins, the rational method was used.

• The DFIRM and FIS report produced in the

FEMA Countywide format in the

North American Vertical Datum of 1988 (NAVD88) NAVD 88 = NGVD 29 – 0.9 (average)

• Preliminary DFIRMs delivered on March 31, 2011894.0’

NAVD 88894.9’NGVD 29

Elevation in NGVD 29

Elevation in NAVD 88

896.0’NAVD 88

896.9’NGVD 29

Datum Conversion of Rockland County

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Vertical Datum Conversion Factors

FLOODING SOURCE 

CONVERSION FACTOR (NGVD 29 TO NAVD 88)

(FT) 

Antrim Creek -0.90Brian Brook -0.89Cedar Pond Brook -0.98Crumm Creek -0.96Demarest Kill -0.97East Branch Hackensack River -0.97East Branch Saddle River -0.93Golf Course Brook -0.91Hackensack River -0.97Hudson River -0.99Hungry Hollow Brook -0.94Lake Deforest -0.97Mahwah River -0.88Mill Creek -0.97Minisceongo Creek -0.97Montebello Creek -0.90Muddy Creek -0.97Nakoma Brook -0.83Nauraushaun Brook -0.96North Branch Pascack Brook -0.94Pascack Brook -0.95Pine Brook -0.94

FLOODING SOURCE 

CONVERSION FACTOR (NGVD 29 TO NAVD 88)

(FT) 

Ramapo River -0.85

South Branch Minisceongo Creek -1.08

Sparkill Creek -0.99

Spook Rock Brook -0.91

Spook Rock Brook Left Channel -0.91

Stony Brook -0.84

Tributary 1 to Hudson River -0.98

Tributary 1 to Nakoma Brook -0.81

Tributary 1 to Ramapo River -0.87

Tributary 1 to West Branch Saddle River

-0.93

Tributary 2 to Ramapo River -0.84

Tributary to Cedar Pond Brook -0.97

West Branch Hackensack River -0.97

West Branch Saddle River -0.93

Willow Tree Brook -0.90

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Rockland County-wide Paneling Scheme

• Some of the communities that did not have mapsmight get new maps with special flood hazard zones

• Some of the communities may be covered with more than one panel

• Paneling scheme createdfrom 1:24,000 USGS quads

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On March 31, 2011 each community received: Preliminary Flood Insurance Study (FIS) report Preliminary Paper Flood Insurance Rate Maps (FIRMs) DVD containing digital FIRM & FIS & fact-sheet and

geographic information system (GIS) data: GIS viewer and preliminary shapefiles

Roles & Responsibilities of Local CommunitiesRoles & Responsibilities of Local Communities:: Review & Comment on these preliminary FIRMs & FIS

FEMA & NYSDEC will be conducting CCO meetings early summer

Flood Risk communications with residents

Local Communities

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Milestones December 2005: Rockland County scoping meetings

Fall 2006: Rockland County-wide Flood Insurance Study/Flood Insurance Rate Maps funded

March 31, 2011: Preliminary Rockland County Flood Maps delivered

Early Summer 2011: CCO meetings with the community officials followed by Open House meetings

Summer 2012: Letter of Final Determination (LFD)

Early 2013: Effective Flood Maps delivered

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Post-Preliminary Process

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Mitigation Plan in NY Update

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Resources

New York State - NFIP Coordinator:

http://www.dec.ny.gov/

New York State Office of Emergency Management: http://www.semo.state.ny.us/

FEMA: www.fema.gov

Floodsmart, the official site of the National Flood Insurance Program (NFIP): www.floodsmart.gov

Risk Assessment, Mapping and Planning Partners: www.RAMPP-team.com

NFIP Reform: www.fema.gov/business/nfip/nfip_reform.shtm

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Questions & Feedback www.RAMPP-TEAM.com/ny.htm: PowerPoint Presentation & fact sheet & FIS & FIRMs & additional

information will be postedContact Information

New York State Department of Environmental Conservation (NYSDEC)

William Nechamen, CFM Kelli Higgins-Roche, CFM Arvind Goswami, PE

518-402-8185 518-402-8185 518-402-8185

Wsnecham@gw.dec.state.ny.us Kahiggin@gw.dec.state.ny.us Aggoswam@gw.dec.state.ny.us

URS - Mapping Partner

John Dromsky-Reed, PE, CFM

973-785-8013 x 350

John_Dromsky-Reed@urscorp.com

FEMA Region II

Alan Springett Richard Einhorn

26 Federal Plaza, 212-680-8503

New York, NY 10278 Richard.Einhorn@dhs.gov

212-680-8557

Alan.Springett@dhs.gov