KEY PROJECT COMPONENTS:

• 1”=500’ Maps

• Data Set Creation for In/Out by Elevation

• Data Conversion from NAD27/NGVD29 to   NAD83/NAVD88

• Contours and spot elevation update ands review

• Metadata

TVGA at the Town of Clarence’s request developed Maps to assist the Town in protesting the most recently releases of the FEMA Flood Insurance Rate Maps (FIRM). 

Utilizing the existing topographic information, provided to the Town by TVGA under a previous assignment, TVGA updated the surface data to the FEMA datum in use of NAD 1983/NAVD 1988.  This was completed by running a batch program within the photogrammetric software KLT Atlas to adjust the spot elevations and breaklines.  Contours were then generated at 1’ and 2’ intervals.

After obtaining the new FEMA FIRM’s from the FEMA mapping consultant, TVGA technicians overlaid the FEMA data for AE Floods Zones and BFE data on the existing Town of Clarence topographic data set.    This data was the re-scaled to 1”=500’ to coincide with the FEMA Maps.  12 sheets were created based on updating the area North of Roll Rd and the areas along Gott Creek and Ransom Creek.  Update text scale and layer information on each of the twelve (12) sheets.

TVGA provided the Town with draft plots of each map for review comment.  Based on the Town’s mark-ups of the draft plots, TVGA will create digital polygons of the areas in question.  Two separate polygon layers were created, one for those areas excluded from the flood plains by elevation and those that are included in the flood plain by elevation.