1. One Company. Unlimited Potential.
Months 6-12
One Company. Unlimited Potential.

2. AUSTIN
BRYAN / COLLEGE STATION
DALLAS
HOUSTON
KATY
ROSENBERG
SAN ANTONIO
THE WOODLANDS

3. Services

4. Floodplain Management
Definition
Floodplain Management is a decision-making process that aims to achieve the wise use of the nation's floodplains.
Environmental Impacts
Health and Safety
Economics
Resiliency
Sustainability
Considerations

5. Floodplain Management
Reality
Insurance
Technology &
Engineering
Regulatory
Science
&
Research

6. Atlas 14 Update
What is NOAA Rainfall Atlas
100 Year Flood: 1% annual chance exceedance
Statistical fact:
1-(0.99)^30 = 27%
chance of a home in the 100-year floodplain will flood over a 30-year mortgage
1-(0.998)^30 = 6%
chance of a home in the 500-year floodplain will flood over a 30-year mortgage
Atlas 14 is an ongoing study used to analyze historical rainfall data in order to update statistical hypothetical rainfall events in Texas.

7. Atlas 14 Update Progress Atlas 14 replaces TP-40 – 1961
Texas is the last state to be updated

8. Atlas 14 Update What’s changed from 1961
Average record length of gauge now over 50 years
Oldest data set from 1836 (Ft. Snelling/Minneapolis St. Paul Airport)
Results
Shows higher intensity during short storms
More regional relationships

9. Atlas 14 Update

10. Atlas 14 – Next Steps Adopted by local agencies Change regulations
Update FEMA maps – Incorporate new technology
Update is scheduled to be completed in October as NOAA Atlas 14 Volume 11 Version 2
Each jurisdiction will be able to analyze the data and determine practical applications for their location through engineering reviews.

11. COH Chapter 19 Update
Changes Effective September 1st for both sets of City of Houston Regulations
Chapter 19 Ordinance – Floodplain Regulations
500-year storm basis for new regulations
Increases 51,000 acres (13% of overall city)
Floodplain mitigation for fill in 500-year
Minimum Slab elevations go from 100 year + 1’ to 500 year + 2’

12. COH Chapter 19 Update

13. COH Chapter 19 Update

14. COH Chapter 9 Chapter 9 of Infrastructure Design Manual Detention
No reduced detention rate for redevelopment
COH is extending their detention review to ETJ projects
COH detention rates will default to higher storage volume if more than one jurisdiction (HCFCD, TxDOT) is involved
Fill Placement
Removing 1-acre Threshold – must demonstrate no impact to sheet flow for all development

15. Harris County Updates Non-Conforming Subdivision (NCS)
NCS developed prior to county extreme sheet flow regulations
Conforming Subdivision (CS)
CS meets criteria set in August 2009 regarding extreme even sheet flow
CS performance in Harvey (less than 1% of permitted structures flooded)
New Development
CS - Move forward as existing regulations with only new requirement that homes be set at minimum 500-year elevation
NCS – cheat sheet

16. Harris County Updates

17. COH County Updates

18. Open House – Regulation Updates