MANASOTA & PEACE RIVER BBDs Meeting Notebook 10-21-09.docx

N150
Polk County NAVD88 Vertical Control Densification
Project Type Cooperative Funding
AOR(s)
Water Supply, Flood Protection, Water Quality, Natural Systems
Basin(s) General Fund (District), Alafia River, Hillsborough River, Peace River
Cooperator(s)
Polk County
Project Manager OWENS, JIM
Task Manager(s)
Status Ongoing
Description
The establishment of an accurate and easily accessible vertical control survey network is an important component in
the development of updated Federal Emergency Management Agency Flood Insurance Rate Maps (FEMA FIRM). The
District, in cooperation with the National Geodetic Survey and the Florida Department of Environmental Protection, has
completed the Distict-wide vertical control densification. This project will further enhance the existing vertical control
network to support FEMA FIRM mapping, topographic data collection and modeling activities. The newly-established
vertical control network will allow the District and local governments to transition from the older and less accurate
vertical control survey network known as the National Geodetic Vertical Datum of 1929 to the more accurate North
American Vertical Datum of 1988 (NAVD88) system. In Polk County this includes running level loops and establishing
bench marks based on NAVD88 along state and county roadways. This project will enable the surveying community to
make an orderly transition to NAVD88 and will allow Polk County to be on the same vertical datum as the District and
to comply with the federal surveying and mapping requirements. This project will densify the NAVD88 vertical control in
Polk County within the District's jurisdiction and will compliment the District's NAVD88 migration project.
Benefits
Densification of benchmarks will support the development of Watershed Management Plans for Polk County thus
contributing to flood protection, natural systems, water quality and water supply. Polk County participates in the
National Flood Insurance Program administered by FEMA and requires that all finished floor elevations be above the
100 year floodplain. This project is a key component in meeting this requirement. Also, the establishment and
implementation of the NAVD 1988 will enable more accurate elevations and mapping throughout the District, and the
conversion to the modern vertical datum will allow the ability to establish accurate and reliable elevations using Global
Positioning System (GPS) technology. Polk County is a participant in FEMA's Community Rating System and has a
Class 8 rating.
Costs
The cost of contractual services for this project is $200,000. The District is the lead on this project and will be
reimbursed by Polk County for $100,000. The District's cost is split between the Alafia River Basin ($15,000), the
General Fund ($15,000), the Hillsborough River Basin ($10,000), and the Peace River Basin ($60,000) based on
approximate area. Additional costs are associated with staff time required to manage the project.
Additional Information
This project will be administered by the District. The vertical control network survey work will be completed by FDEP
and NGS. All control network data produced by this project will be made available through Internet access via LABINS
web site and the NGS web site.
020 - Peace River Basin 345