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CITY OF COPPERAS COVE, TEXASAAggeennddaa IItteemm NNoo..
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331122--00008844
[email protected]
SUBJECT: Presentation and discussion with direction to staff regarding the Final Draft of the City’s Drainage Master Plan Phase 2.
1. BACKGROUND/HISTORY
The Drainage Master Plan Phase 1 was completed in 2014 by Lockwood Andrews and Newnam (LAN). This master plan identified the 10 highest priority sites throughout the City. These top 10 projects were presented to the Bond committee and 6 of these projects were placed in the Drainage component of the 2014 Bond. A contract was executed with Freese and Nichols (FNI) in March 2015 to perform the Drainage Master Plan Phase 2 (DMP2) study.
2. FINDINGS/CURRENT ACTIVITY
FNI has completed the DMP2 study and identified a total of 30 projects in areas that will need improvements. These projects include the 4 top ten projects identified in the Phase 1 Study that were not included in the 2014 Bond as well as 26 additional projects that have been identified in this study. The study provides a CIP for each of the projects identified in the study. This DMP2 will be presented to the Planning and Zoning Commission on December 22 for recommendation of the Ordinance to adopt the DMP2 to City Council. The ordinance for adopting the DMP2 will be presented to City Council in January 2016. FNI will make a presentation to go over the draft DMP2 and receive any comments City Council will have.
3. FINANCIAL IMPACT
4. ACTION OPTIONS/RECOMMENDATION
This is City Council’s opportunity to provide further comment on the Drainage Master Plan Phase 2.
5. ENCLOSURES A. Presentation by FNI
CITY OF BUDA
Innovative approaches ... practical results ... outstanding service
• Two phase master plan to identify and prioritize City drainage problems
– PHASE 1 completed in 2014
• Goal: identify 10 highest priority sites throughout City
• Top six resulted in 2014 Drainage Bond Projects, which are under design
– PHASE 2 completed in 2015
• Developed approach for prioritizing and addressing other noted problems and future problems
BACKGROUND
• Developed conceptual solutions
• Developed a database for City’s future use
PROJECT OVERVIEW
• PHASE 2 Projects: – Total of 30 projects
– Phase 1 projects that were not included in bond package
– Problem areas included flooding, erosion, and maintenance
• Evaluated existing conditions by: – reviewing past studies – documented flooding concerns – site visits – GIS data
– limited modeling
PROBLEM AREA IDENTIFICATION
LIST OF PROJECTS Final Rank Project ID ProjectName Description
1 GC4 Garlic Creek Culvert 3 Flood Early Warning System (FEWS)
1 OC2 FM 967 Onion Creek Bridge Flood Early Warning System (FEWS)
3 GCT2 Garlic Creek Tributary Under FM 967 Upsize crossing
4 BV2 West Lifshultz Area Flooding Channel, ditch, culvert improvements
5 AB2 Hillside Terrace Neighborhood Flooding Channel improvements
6 AB1 Park 35 South Channel Erosion Channel repairs (grading and drop structures)
6 GC2 Garlic Creek Culvert 2 Channel construction and culvert improvements
8 OC1 Cole Springs Roadway Flooding Flood Early Warning System (FEWS)
9 OC3 Garison Road Area Flooding New stormdrain and channel improvements
9 OTS5 Old Town South Lift Station Access Road Upsize crossing
11 GC5 Whispering Hollows Street / Residence Flooding Pond and outfall channel modifications
12 GC1 Garlic Creek Culvert 1 Flood Early Warning System (FEWS)
13 AB6 Green Meadows Channel Erosion and Slope Stability Erosion repairs and armoring
14 AB5 Green Meadows Outfall Outfall repairs and downstream channel improvments
15 OC5 Old San Antonio Rd Ditch Improve driveway culverts and aromoring
15 OTS1 Old Town South Culvert 1 Upsize crossing
17 GC3 Cullen Blvd. Water Utility Station Install driveway barrier and flap valves
18 BV4 Sequoyah Subdivision Flooding Upsize crossings, minor channel repair
19 BV6 Chatlift Area Flooding Channel construction and culvert improvements
20 AT1 Antioch Tributary Culvert Upsize crossing
21 BC1 Brushy Creek Culvert 1 Flood Early Warning System (FEWS)
21 BC2 Brushy Creek Culvert 2 Flood Early Warning System (FEWS)
21 BC3 Brushy Creek Culvert 3 Flood Early Warning System (FEWS)
21 OC4 Onion Creek Low Water Crossing Flood Early Warning System (FEWS)
25 AB3 Apple Blossom Home Flooding Channel realignment/construction
26 RB1 Interstate Drive Culverts Upsize crossing
27 BV7 Ashford Park Outfall Pipe repair and outfall protection
28 AB4 Dacy Lane Low Water Crossing Culvert improvements and FEWS
28 BV5 IH-35 Frontage Road Flooding Minor grading and outfall repair
30 OC6 Ash/Main St. Intersection Flooding Install curb and gutter and raised sidewalk
Innovative approaches ... practical results ... outstanding service
CIP DEVELOPMENT
• Developed proposed improvements
• Looked for overlap with the City’s Transportation Master Plan
Innovative approaches ... practical results ... outstanding service
PROPOSED IMPROVEMENTS
• Channel Widening/Realignment
• Buyouts
OPINION OF PROBABLE PROJECT COSTS
• Project cost included:
PROJECT PRIORITIZATION
PROJECT PRIORITIZATION
PROJECT PRIORITIZATION
2 Street Flooding 11
4 Properties at Risk 8
4 Project Cost 8
Score
Projects
Establish
Criteria
Number of Structures
> 5 8
Structures at Risk
Major Arterial 4
Minor Arterial 3
+3 points if sole route for ingress/egress for properties
Street Flooding
Project Cost
> 5 10
PROJECT PRIORITIZATION
Score
1 OC2 FM 967 Onion Creek Bridge 10 0 4 8 4 5 317 1 GC4 Garlic Creek Culvert 3 10 0 4 8 4 5 317 3 GCT2 Garlic Creek Tributary Under FM 967 10 0 4 7 4 5 309 4 BV2 West Lifshultz Area Flooding 4 7 8 4 7 0 301 5 AB2 Hillside Terrace Neighborhood Flooding 0 10 8 5 0 5 295 6 GC2 Garlic Creek Culvert 2 10 0 4 3 4 5 277 6 AB1 Park 35 South Channel Erosion 0 7 6 6 4 5 277 8 OC1 Cole Springs Roadway Flooding 3 0 8 8 0 5 272 9 OC3 Garison Road Area Flooding 6 4 4 7 0 5 269 9 OTS5 Old Town South Lift Station Access Road 6 4 4 7 0 5 269 11 GC5 Whispering Hollows Street / Residence Flooding 0 10 8 4 4 0 260 12 GC1 Garlic Creek Culvert 1 7 0 4 8 0 5 256 13 AB6 Green Meadows Channel Erosion and Slope Stability 0 10 6 7 4 0 254 14 AB5 Green Meadows Outfall 3 0 4 8 4 5 240 15 OC5 Old San Antonio Rd Ditch 0 4 6 4 4 5 237
Establish
Criteria
DELIVERABLES
• Database Training
GIS MAP AND DATA LINK
Innovative approaches ... practical results ... outstanding service
LIVING DATABASE
SUMMARY REPORT
DATABASE ATTRIBUTE TABLE
PROJECT HIGHLIGHT (BV2)
PROJECT HIGHLIGHT (GC5)
FLOOD INFORMATION
• How big were the Halloween Events
• Design standards
WHAT IS THE 100-YEAR STORM?
• 1 in 100 chance of rainfall/streamflow being exceeded during
any rainfall event in a given year • 1% Annual Exceedance Probability • 26% chance will happen during a 30-year period • Time between events varies
on data from 1940-1975
HALLOWEEN 2013 RAINFALL TOTALS
HALLOWEEN 2015 RAINFALL TOTALS
Table 2-3. Depth-Duration-Frequency Table for Austin and Travis County
Depth of Precipitation (in inches)
Recurrence Interval (year)
5 min* 15 min 30 min 1-hr 2-hr 3-hr 6-hr 12-hr 24-hr
2 0.48 0.98 1.32 1.72 2.16 2.32 2.67 3.06 3.44
5 0.62 1.26 1.71 2.28 2.89 3.13 3.56 4.07 4.99
10 0.71 1.47 1.98 2.68 3.42 3.71 4.21 4.81 6.1
25 0.84 1.76 2.36 3.28 4.2 4.55 5.14 5.9 7.64
50 0.94 2.01 2.68 3.79 4.88 5.28 5.94 6.86 8.87
100 1.05 2.29 3.04 4.37 5.66 6.11 6.85 7.96 10.2
250 1.21 2.73 3.57 5.26 6.86 7.38 8.24 9.67 12
500 1.33 3.11 4.02 6.06 7.94 8.51 9.47 11.2 13.5
* The 5-min rainfall depths were calculated using the 5-min rainfall intensity values from Table 2-4.
RAINFALL DEPTH
Table 2-3. Depth-Duration-Frequency Table for Austin and Travis County
Depth of Precipitation (in inches)
Recurrence Interval (year)
5 min* 15 min 30 min 1-hr 2-hr 3-hr 6-hr 12-hr 24-hr
2 0.48 0.98 1.32 1.72 2.16 2.32 2.67 3.06 3.44
5 0.62 1.26 1.71 2.28 2.89 3.13 3.56 4.07 4.99
10 0.71 1.47 1.98 2.68 3.42 3.71 4.21 4.81 6.1
25 0.84 1.76 2.36 3.28 4.2 4.55 5.14 5.9 7.64
50 0.94 2.01 2.68 3.79 4.88 5.28 5.94 6.86 8.87
100 1.05 2.29 3.04 4.37 5.66 6.11 6.85 7.96 10.2
250 1.21 2.73 3.57 5.26 6.86 7.38 8.24 9.67 12
500 1.33 3.11 4.02 6.06 7.94 8.51 9.47 11.2 13.5
* The 5-min rainfall depths were calculated using the 5-min rainfall intensity values from Table 2-4.
RAINFALL DEPTH (HALLOWEEN 2013)
9.69
9.72
Table 2-3. Depth-Duration-Frequency Table for Austin and Travis County
Depth of Precipitation (in inches)
Recurrence Interval (year)
5 min* 15 min 30 min 1-hr 2-hr 3-hr 6-hr 12-hr 24-hr
2 0.48 0.98 1.32 1.72 2.16 2.32 2.67 3.06 3.44
5 0.62 1.26 1.71 2.28 2.89 3.13 3.56 4.07 4.99
10 0.71 1.47 1.98 2.68 3.42 3.71 4.21 4.81 6.1
25 0.84 1.76 2.36 3.28 4.2 4.55 5.14 5.9 7.64
50 0.94 2.01 2.68 3.79 4.88 5.28 5.94 6.86 8.87
100 1.05 2.29 3.04 4.37 5.66 6.11 6.85 7.96 10.2
250 1.21 2.73 3.57 5.26 6.86 7.38 8.24 9.67 12
500 1.33 3.11 4.02 6.06 7.94 8.51 9.47 11.2 13.5
* The 5-min rainfall depths were calculated using the 5-min rainfall intensity values from Table 2-4.
RAINFALL DEPTH (HALLOWEEN 2015)
Innovative approaches ... practical results ... outstanding service
0.1
1.0
10.0
2-yr
50-yr
15 min 30 min 60 min 2 hr 3 hr 6 hr 12 hr 24 hr
RAINFALL INTENSITY
ROADWAY NETWORK
City of Buda1
Hays County2
Country Lane, Local 25-yr Frequency Event HW Elevation < 6" Above Roadway
Collector 25-yr Frequency Event HW Elevation < 6" Above Roadway
Major Collector 100-yr Frequency Event HW Elevation < 6" Above Roadway
Minor/Major Arterial 100-yr Frequency Event HW Elevation < 6" Above Roadway
TxDOT3
Minor Arterials and Collectors
Small Bridges 25-yr Frequency Event HW Elevation < Roadway
Major River Crossings 50-yr Frequency Event HW Elevation < Roadway
Principal Arterials Culverts and Small Bridges 25-yr Frequency Event HW Elevation < Roadway
Major River Crossings 50-yr Frequency Event HW Elevation < Roadway
Freeways (main lanes) 50-yr Frequency Event HW Elevation < Roadway
DESIGN CRITERIA COMPARISON
Local Flooding Entity Type Roadway Type Criteria
City of Buda1
Infrastructure Capacity All
25-year design storm frequency 100-year event flows must be contained within the ROW
Street Flow
Collector Residential/Neighborhood Minimum Clear Width = 12 ft
Other Minimum Clear Width = 12 ft (each direction)
Arterial 4 lanes one way/8 lanes divided Minimum Clear Width = 24 ft (each direction)
Other Minimum Clear Width = 12 ft (each direction)
Hays County2 Infrastructure
Local 10-year design storm frequency
Minor Collector 15-year design storm frequency
Major Collector 25-year design storm frequency
Minor/Major Arterial 25-year design storm frequency
All 100-year event flows must be contained within the ROW
TxDOT3
Minor Arterials and Collectors 10-year design storm frequency
Principal Arterials 25-year design storm frequency
Freeways (main lanes) 50-year design storm frequency Interstates and
Controlled Access Highways
Other 10-year design storm frequency
Other Highways and Frontage Roads
Depressed Roadways 25-year design storm frequency
Other 5-year design storm frequency
Street Flow
Minor Highways Minimum Clear Width = One lane (each direction)
Major Highways (2 or more lanes in each direction) Minimum Clear Width = All inside lanes
Interstates and Controlled Access Highways Minimum Clear Width = All inside lanes plus 1/2 the width of outer lane
DESIGN CRITERIA COMPARISON
TYPICAL ROADWAY CONVEYANCE
WHAT IF IT RAINS MORE THAN 1”?
1”
3”
4”
$2 M $3 M $4 M $1 M $0.0 M
$1.9M
$2.5M
$3.0M
$3.5M
$4.1M
$4.7M
$5.1M
EXPECTED ANNUAL DAMAGE
Expected Annual Damages
100- VS. 500-YR (1% VS. 0.2% AEP)
Innovative approaches ... practical results ... outstanding service
FLOOD DEPTH AND WIDTH
Kim Patak, P.E., CFM, CPESC, ENV SP
Freese and Nichols, Inc.
[email protected]
SUBJECT: Presentation and discussion with direction to staff regarding the Final Draft of the City’s Drainage Master Plan Phase 2.
1. BACKGROUND/HISTORY
The Drainage Master Plan Phase 1 was completed in 2014 by Lockwood Andrews and Newnam (LAN). This master plan identified the 10 highest priority sites throughout the City. These top 10 projects were presented to the Bond committee and 6 of these projects were placed in the Drainage component of the 2014 Bond. A contract was executed with Freese and Nichols (FNI) in March 2015 to perform the Drainage Master Plan Phase 2 (DMP2) study.
2. FINDINGS/CURRENT ACTIVITY
FNI has completed the DMP2 study and identified a total of 30 projects in areas that will need improvements. These projects include the 4 top ten projects identified in the Phase 1 Study that were not included in the 2014 Bond as well as 26 additional projects that have been identified in this study. The study provides a CIP for each of the projects identified in the study. This DMP2 will be presented to the Planning and Zoning Commission on December 22 for recommendation of the Ordinance to adopt the DMP2 to City Council. The ordinance for adopting the DMP2 will be presented to City Council in January 2016. FNI will make a presentation to go over the draft DMP2 and receive any comments City Council will have.
3. FINANCIAL IMPACT
4. ACTION OPTIONS/RECOMMENDATION
This is City Council’s opportunity to provide further comment on the Drainage Master Plan Phase 2.
5. ENCLOSURES A. Presentation by FNI
CITY OF BUDA
Innovative approaches ... practical results ... outstanding service
• Two phase master plan to identify and prioritize City drainage problems
– PHASE 1 completed in 2014
• Goal: identify 10 highest priority sites throughout City
• Top six resulted in 2014 Drainage Bond Projects, which are under design
– PHASE 2 completed in 2015
• Developed approach for prioritizing and addressing other noted problems and future problems
BACKGROUND
• Developed conceptual solutions
• Developed a database for City’s future use
PROJECT OVERVIEW
• PHASE 2 Projects: – Total of 30 projects
– Phase 1 projects that were not included in bond package
– Problem areas included flooding, erosion, and maintenance
• Evaluated existing conditions by: – reviewing past studies – documented flooding concerns – site visits – GIS data
– limited modeling
PROBLEM AREA IDENTIFICATION
LIST OF PROJECTS Final Rank Project ID ProjectName Description
1 GC4 Garlic Creek Culvert 3 Flood Early Warning System (FEWS)
1 OC2 FM 967 Onion Creek Bridge Flood Early Warning System (FEWS)
3 GCT2 Garlic Creek Tributary Under FM 967 Upsize crossing
4 BV2 West Lifshultz Area Flooding Channel, ditch, culvert improvements
5 AB2 Hillside Terrace Neighborhood Flooding Channel improvements
6 AB1 Park 35 South Channel Erosion Channel repairs (grading and drop structures)
6 GC2 Garlic Creek Culvert 2 Channel construction and culvert improvements
8 OC1 Cole Springs Roadway Flooding Flood Early Warning System (FEWS)
9 OC3 Garison Road Area Flooding New stormdrain and channel improvements
9 OTS5 Old Town South Lift Station Access Road Upsize crossing
11 GC5 Whispering Hollows Street / Residence Flooding Pond and outfall channel modifications
12 GC1 Garlic Creek Culvert 1 Flood Early Warning System (FEWS)
13 AB6 Green Meadows Channel Erosion and Slope Stability Erosion repairs and armoring
14 AB5 Green Meadows Outfall Outfall repairs and downstream channel improvments
15 OC5 Old San Antonio Rd Ditch Improve driveway culverts and aromoring
15 OTS1 Old Town South Culvert 1 Upsize crossing
17 GC3 Cullen Blvd. Water Utility Station Install driveway barrier and flap valves
18 BV4 Sequoyah Subdivision Flooding Upsize crossings, minor channel repair
19 BV6 Chatlift Area Flooding Channel construction and culvert improvements
20 AT1 Antioch Tributary Culvert Upsize crossing
21 BC1 Brushy Creek Culvert 1 Flood Early Warning System (FEWS)
21 BC2 Brushy Creek Culvert 2 Flood Early Warning System (FEWS)
21 BC3 Brushy Creek Culvert 3 Flood Early Warning System (FEWS)
21 OC4 Onion Creek Low Water Crossing Flood Early Warning System (FEWS)
25 AB3 Apple Blossom Home Flooding Channel realignment/construction
26 RB1 Interstate Drive Culverts Upsize crossing
27 BV7 Ashford Park Outfall Pipe repair and outfall protection
28 AB4 Dacy Lane Low Water Crossing Culvert improvements and FEWS
28 BV5 IH-35 Frontage Road Flooding Minor grading and outfall repair
30 OC6 Ash/Main St. Intersection Flooding Install curb and gutter and raised sidewalk
Innovative approaches ... practical results ... outstanding service
CIP DEVELOPMENT
• Developed proposed improvements
• Looked for overlap with the City’s Transportation Master Plan
Innovative approaches ... practical results ... outstanding service
PROPOSED IMPROVEMENTS
• Channel Widening/Realignment
• Buyouts
OPINION OF PROBABLE PROJECT COSTS
• Project cost included:
PROJECT PRIORITIZATION
PROJECT PRIORITIZATION
PROJECT PRIORITIZATION
2 Street Flooding 11
4 Properties at Risk 8
4 Project Cost 8
Score
Projects
Establish
Criteria
Number of Structures
> 5 8
Structures at Risk
Major Arterial 4
Minor Arterial 3
+3 points if sole route for ingress/egress for properties
Street Flooding
Project Cost
> 5 10
PROJECT PRIORITIZATION
Score
1 OC2 FM 967 Onion Creek Bridge 10 0 4 8 4 5 317 1 GC4 Garlic Creek Culvert 3 10 0 4 8 4 5 317 3 GCT2 Garlic Creek Tributary Under FM 967 10 0 4 7 4 5 309 4 BV2 West Lifshultz Area Flooding 4 7 8 4 7 0 301 5 AB2 Hillside Terrace Neighborhood Flooding 0 10 8 5 0 5 295 6 GC2 Garlic Creek Culvert 2 10 0 4 3 4 5 277 6 AB1 Park 35 South Channel Erosion 0 7 6 6 4 5 277 8 OC1 Cole Springs Roadway Flooding 3 0 8 8 0 5 272 9 OC3 Garison Road Area Flooding 6 4 4 7 0 5 269 9 OTS5 Old Town South Lift Station Access Road 6 4 4 7 0 5 269 11 GC5 Whispering Hollows Street / Residence Flooding 0 10 8 4 4 0 260 12 GC1 Garlic Creek Culvert 1 7 0 4 8 0 5 256 13 AB6 Green Meadows Channel Erosion and Slope Stability 0 10 6 7 4 0 254 14 AB5 Green Meadows Outfall 3 0 4 8 4 5 240 15 OC5 Old San Antonio Rd Ditch 0 4 6 4 4 5 237
Establish
Criteria
DELIVERABLES
• Database Training
GIS MAP AND DATA LINK
Innovative approaches ... practical results ... outstanding service
LIVING DATABASE
SUMMARY REPORT
DATABASE ATTRIBUTE TABLE
PROJECT HIGHLIGHT (BV2)
PROJECT HIGHLIGHT (GC5)
FLOOD INFORMATION
• How big were the Halloween Events
• Design standards
WHAT IS THE 100-YEAR STORM?
• 1 in 100 chance of rainfall/streamflow being exceeded during
any rainfall event in a given year • 1% Annual Exceedance Probability • 26% chance will happen during a 30-year period • Time between events varies
on data from 1940-1975
HALLOWEEN 2013 RAINFALL TOTALS
HALLOWEEN 2015 RAINFALL TOTALS
Table 2-3. Depth-Duration-Frequency Table for Austin and Travis County
Depth of Precipitation (in inches)
Recurrence Interval (year)
5 min* 15 min 30 min 1-hr 2-hr 3-hr 6-hr 12-hr 24-hr
2 0.48 0.98 1.32 1.72 2.16 2.32 2.67 3.06 3.44
5 0.62 1.26 1.71 2.28 2.89 3.13 3.56 4.07 4.99
10 0.71 1.47 1.98 2.68 3.42 3.71 4.21 4.81 6.1
25 0.84 1.76 2.36 3.28 4.2 4.55 5.14 5.9 7.64
50 0.94 2.01 2.68 3.79 4.88 5.28 5.94 6.86 8.87
100 1.05 2.29 3.04 4.37 5.66 6.11 6.85 7.96 10.2
250 1.21 2.73 3.57 5.26 6.86 7.38 8.24 9.67 12
500 1.33 3.11 4.02 6.06 7.94 8.51 9.47 11.2 13.5
* The 5-min rainfall depths were calculated using the 5-min rainfall intensity values from Table 2-4.
RAINFALL DEPTH
Table 2-3. Depth-Duration-Frequency Table for Austin and Travis County
Depth of Precipitation (in inches)
Recurrence Interval (year)
5 min* 15 min 30 min 1-hr 2-hr 3-hr 6-hr 12-hr 24-hr
2 0.48 0.98 1.32 1.72 2.16 2.32 2.67 3.06 3.44
5 0.62 1.26 1.71 2.28 2.89 3.13 3.56 4.07 4.99
10 0.71 1.47 1.98 2.68 3.42 3.71 4.21 4.81 6.1
25 0.84 1.76 2.36 3.28 4.2 4.55 5.14 5.9 7.64
50 0.94 2.01 2.68 3.79 4.88 5.28 5.94 6.86 8.87
100 1.05 2.29 3.04 4.37 5.66 6.11 6.85 7.96 10.2
250 1.21 2.73 3.57 5.26 6.86 7.38 8.24 9.67 12
500 1.33 3.11 4.02 6.06 7.94 8.51 9.47 11.2 13.5
* The 5-min rainfall depths were calculated using the 5-min rainfall intensity values from Table 2-4.
RAINFALL DEPTH (HALLOWEEN 2013)
9.69
9.72
Table 2-3. Depth-Duration-Frequency Table for Austin and Travis County
Depth of Precipitation (in inches)
Recurrence Interval (year)
5 min* 15 min 30 min 1-hr 2-hr 3-hr 6-hr 12-hr 24-hr
2 0.48 0.98 1.32 1.72 2.16 2.32 2.67 3.06 3.44
5 0.62 1.26 1.71 2.28 2.89 3.13 3.56 4.07 4.99
10 0.71 1.47 1.98 2.68 3.42 3.71 4.21 4.81 6.1
25 0.84 1.76 2.36 3.28 4.2 4.55 5.14 5.9 7.64
50 0.94 2.01 2.68 3.79 4.88 5.28 5.94 6.86 8.87
100 1.05 2.29 3.04 4.37 5.66 6.11 6.85 7.96 10.2
250 1.21 2.73 3.57 5.26 6.86 7.38 8.24 9.67 12
500 1.33 3.11 4.02 6.06 7.94 8.51 9.47 11.2 13.5
* The 5-min rainfall depths were calculated using the 5-min rainfall intensity values from Table 2-4.
RAINFALL DEPTH (HALLOWEEN 2015)
Innovative approaches ... practical results ... outstanding service
0.1
1.0
10.0
2-yr
50-yr
15 min 30 min 60 min 2 hr 3 hr 6 hr 12 hr 24 hr
RAINFALL INTENSITY
ROADWAY NETWORK
City of Buda1
Hays County2
Country Lane, Local 25-yr Frequency Event HW Elevation < 6" Above Roadway
Collector 25-yr Frequency Event HW Elevation < 6" Above Roadway
Major Collector 100-yr Frequency Event HW Elevation < 6" Above Roadway
Minor/Major Arterial 100-yr Frequency Event HW Elevation < 6" Above Roadway
TxDOT3
Minor Arterials and Collectors
Small Bridges 25-yr Frequency Event HW Elevation < Roadway
Major River Crossings 50-yr Frequency Event HW Elevation < Roadway
Principal Arterials Culverts and Small Bridges 25-yr Frequency Event HW Elevation < Roadway
Major River Crossings 50-yr Frequency Event HW Elevation < Roadway
Freeways (main lanes) 50-yr Frequency Event HW Elevation < Roadway
DESIGN CRITERIA COMPARISON
Local Flooding Entity Type Roadway Type Criteria
City of Buda1
Infrastructure Capacity All
25-year design storm frequency 100-year event flows must be contained within the ROW
Street Flow
Collector Residential/Neighborhood Minimum Clear Width = 12 ft
Other Minimum Clear Width = 12 ft (each direction)
Arterial 4 lanes one way/8 lanes divided Minimum Clear Width = 24 ft (each direction)
Other Minimum Clear Width = 12 ft (each direction)
Hays County2 Infrastructure
Local 10-year design storm frequency
Minor Collector 15-year design storm frequency
Major Collector 25-year design storm frequency
Minor/Major Arterial 25-year design storm frequency
All 100-year event flows must be contained within the ROW
TxDOT3
Minor Arterials and Collectors 10-year design storm frequency
Principal Arterials 25-year design storm frequency
Freeways (main lanes) 50-year design storm frequency Interstates and
Controlled Access Highways
Other 10-year design storm frequency
Other Highways and Frontage Roads
Depressed Roadways 25-year design storm frequency
Other 5-year design storm frequency
Street Flow
Minor Highways Minimum Clear Width = One lane (each direction)
Major Highways (2 or more lanes in each direction) Minimum Clear Width = All inside lanes
Interstates and Controlled Access Highways Minimum Clear Width = All inside lanes plus 1/2 the width of outer lane
DESIGN CRITERIA COMPARISON
TYPICAL ROADWAY CONVEYANCE
WHAT IF IT RAINS MORE THAN 1”?
1”
3”
4”
$2 M $3 M $4 M $1 M $0.0 M
$1.9M
$2.5M
$3.0M
$3.5M
$4.1M
$4.7M
$5.1M
EXPECTED ANNUAL DAMAGE
Expected Annual Damages
100- VS. 500-YR (1% VS. 0.2% AEP)
Innovative approaches ... practical results ... outstanding service
FLOOD DEPTH AND WIDTH
Kim Patak, P.E., CFM, CPESC, ENV SP
Freese and Nichols, Inc.