1. FLOOD STUDY Rockland County, NY
FEMA REGION II
April 13, 2011

2. Agenda Introductions and Roll Call Objectives
Map Modernization (MapMod) Program Overview
Rockland County MapMod Update
Milestones
Questions & Feedback

3. 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 II
Project 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

4. 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

5. 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

6. 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, 2011
894.0’
NAVD 88
894.9’
NGVD 29
Elevation in NGVD 29
Elevation in NAVD 88
896.0’
896.9’
Datum Conversion of Rockland County

7. Vertical Datum Conversion Factors
FLOODING SOURCE
CONVERSION FACTOR (NGVD 29 TO NAVD 88) (FT)
Antrim Creek
-0.90
Brian Brook
-0.89
Cedar Pond Brook
-0.98
Crumm Creek
-0.96
Demarest Kill
-0.97
East Branch Hackensack River
East Branch Saddle River
-0.93
Golf Course Brook
-0.91
Hackensack River
Hudson River
-0.99
Hungry Hollow Brook
-0.94
Lake Deforest
Mahwah River
-0.88
Mill Creek
Minisceongo Creek
Montebello Creek
Muddy Creek
Nakoma Brook
-0.83
Nauraushaun Brook
North Branch Pascack Brook
Pascack Brook
-0.95
Pine Brook
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
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
Tributary to Cedar Pond Brook
-0.97
West Branch Hackensack River
West Branch Saddle River
Willow Tree Brook
-0.90

8. Rockland County-wide Paneling Scheme
Some of the communities that did not have maps
might get new maps with special flood hazard zones
Some of the communities may be covered
with more than one panel
Paneling scheme created
from 1:24,000 USGS quads
Town of Stony Point

9. Local Communities Roles & Responsibilities of Local Communities:
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 Communities:
Review & Comment on these preliminary FIRMs & FIS
FEMA & NYSDEC will be conducting CCO meetings early summer
Flood Risk communications with residents

10. 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

11. Post-Preliminary Process

12. Mitigation Plan in NY Update

13. Resources New York State - NFIP Coordinator:
New York State Office of Emergency Management:
FEMA:
Floodsmart, the official site of the National Flood Insurance Program (NFIP):
Risk Assessment, Mapping and Planning Partners:
NFIP Reform:

14. Questions & Feedback
PowerPoint Presentation & fact sheet & FIS & FIRMs & additional information will be posted
Contact Information
New York State Department of Environmental Conservation (NYSDEC)
William Nechamen, CFM Kelli Higgins-Roche, CFM Arvind Goswami, PE
URS - Mapping Partner
John Dromsky-Reed, PE, CFM
x 350
FEMA Region II
Alan Springett Richard Einhorn
26 Federal Plaza,
New York, NY