1. FEMA and Stream Restoration
Hatchet Grove Tributary
Conditional Letter of Map Revision
& Letter of Map Revision
Process

2. Project Overview Two Projects – Private and Public
Prestonwood Country Club
Golf course redesign and stream restoration
Town of Morrisville
Construction of Morrisville Park and stream restoration
One Stream – FEMA regulated
Hatchet Grove Tributary – Zone AE w/ FW
Tributary to Crabtree Creek in Wake County, NC

3. Project Overview
Prestonwood Country Club

4. Project Overview Prestonwood Country Club Background
Maintenance & Drainage Issue
Alternative Analysis for drainage problems
Functionality and appearance of stream was undesirable for golf course design
Withers & Ravenel partnered and completed the engineering design
Redesign & Restoration
Relocated 3,500 LF of stream
Five of the six existing golf cart bridges were replaced by two bridges
Stream Restoration funded by EEP

5. Project Overview
Morrisville Community Park

6. Project Overview Morrisville Community Park
Provided engineering design services for the Town of Morrisville’s proposed park
Ball fields
Tennis Courts
Play Ground & Picnic Area
Greenway Trail – TWO BRIDGE CROSSINGS!
Introduction of Stream Restoration
Funding –vs- Mitigation Credit
Town used the site as dedicated mitigation for EEP
Other Benefits
Aesthetics
Maintenance
Safety

7. Project Overview Hatchet Grove Tributary Crabtree Creek
Prestonwood Golf Course
Morrisville Community Park
Hatchet Grove Tributary
Crabtree Creek

8. Project Overview

9. Procedure Hatchet Grove Tributary: Stream Restoration
Designed new stream cross section to contain the 2-year design storm at bank-full and targeted to contain the 100-year design storm within the floodplain bench

10. Project Overview Hatchet Grove Tributary: Stream Restoration
Channel and profile design was completed – sized two bridges on golf course and two bridges on greenway

11. Results
100-year water surface elevations for the proposed conditions were lowered for the majority of the stream
Increases under 1’ occurred at six out of the 55 cross sections
Conditional Letter of Map Revision approved May 2003

12. Project Overview

13. Project Overview

14. Letter of Map Revision (LOMR)
Hatchet Grove Tributary: As-Built
Obtained As-Built survey of stream restoration and bridges
Incorporated survey data into approved CLOMR model
Realigned cross sections as needed for final stream alignment
Updated new bridge locations on golf course

15. Letter of Map Revision (LOMR)
Hatchet Grove Tributary: As-Built

16. Letter of Map Revision (LOMR)
Hatchet Grove Tributary: As-Built FEMA Study
The As-Built model was finalized and the FEMA submittal for the LOMR was prepared.

17. RESULTS Hatchet Grove Tributary: As-Built FEMA Study
100-year water surface elevations for the LOMR are 0.39 ft lower on average than the Effective model and 0.11 ft lower than the CLOMR model
Increases under 1’ occurred at eight of the cross sections
Letter of Map Revision submitted April 2005