The document discusses a stormwater rehabilitation project in Charlotte, North Carolina called the Hill Street SDIP. It describes using XPSWMM software to model existing stormwater conditions, including validating the model with a significant past storm event, and modeling a 100-year storm. The model showed most of the existing stormwater infrastructure to be deficient. Proposed improvements included realigning and upsizing 4.1 miles of storm systems and 459 drainage structures, as well as 4000 feet of utility relocations, to reduce flooding risks.

1. Danee McGee, PE, CFM
Stormwater Rehabilitation and XPSWMM
Crystal Williams, PE, CFM, LEED AP
Cameron Long, PE,

2. Stormwater Improvement Projects
Charlotte Mecklenburg Stormwater Services
2 | Stormwater Rehabilitation and XPSWMM October 29, 2015
• Process:
• Survey
• Existing Conditions
• City Design Standard
• Alternative Analysis
• Selected Alternative
• Design
• Real Estate
• Bid
• Construction
Goal: To provide a storm drainage system that is safe, clean, and cost effective

3. Hill Street SDIP
Existing Conditions
3 | Stormwater Rehabilitation and XPSWMM October 29, 2015

4. Hill Street SDIP
4 | Stormwater Rehabilitation and XPSWMM October 29, 2015
• Urban Environment
• Drains 25% of
downtown Charlotte
• Existing Environmental
Concerns
• Extensive Existing
Utilities to avoid or
relocate
• Existing systems
underneath buildings

5. Hill Street SDIP
Urban Environment
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6. • XPSWMM was determined to be the best option
for modeling this system due to the limited open
channels, and highly urban nature of the
watershed.
• XPSWMM is a dynamic hydraulic and hydrologic
modeling software that combines 1D calculations
for pipe flow with 2D overland flow calculations
in order to fully understand the project
area storm system and flooding issues.
Hill Street SDIP
Existing Conditions – Modeling Software
6 | Stormwater Rehabilitation and XPSWMM October 29, 2015

7. Hill Street SDIP
Existing Conditions – Creating the Model
7 | Stormwater Rehabilitation and XPSWMM October 29, 2015
• Base Model
• Load in TIN surface
• Set Rain Data and Area (SCS Method or Rain on Grid)
• Load in Grid Extents (everywhere you want water to flow), set Grid cell size and
orientation.
• Set Land Use/Roughness

8. Hill Street SDIP
Existing Conditions – Creating the Model
8 | Stormwater Rehabilitation and XPSWMM October 29, 2015
Inlets and Pipes– Linked to Surface

9. Hill Street SDIP
Existing Conditions – Creating the Model
9 | Stormwater Rehabilitation and XPSWMM October 29, 2015
• Channels
• Pull Cross Sections
directly from
Surface
• Link Channel to
Surface
• 1D/2D Interface
• 1D/2D Connections

10. Hill Street SDIP
Existing Conditions – Creating the Model
10 | Stormwater Rehabilitation and XPSWMM October 29, 2015
Buildings (& roof drainage)

11. • Interactive Interface
• Depths
• Velocities
• Flows
• Exporting
• Tables
• Profile
• Videos
• Images
Hill Street SDIP
Existing Conditions –Viewing the Results
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12. • A significant storm event occurred on August 5, 2011 where photos and
videos of the flooding in the project area were taken and provided
• Rain data was obtained from nearby rain gauge, and the storm event was
run through the Existing Conditions XPSWMM Model for Hill Street
• The “validation” storm event produced results similar to field observations
Hill Street SDIP
Existing Conditions – Validation Storm
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13. Hill Street SDIP
Existing Conditions – Validation Storm
13 | Stormwater Rehabilitation and XPSWMM October 29, 2015

14. Hill Street SDIP
Existing Conditions – Validation Storm
14 | Stormwater Rehabilitation and XPSWMM October 29, 2015

15. Hill Street SDIP
Existing Conditions – 100yr6hr Storm
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16. 16 | Stormwater Rehabilitation and XPSWMM October 29, 2015

17. Hill Street SDIP
Existing Conditions – Deficiencies
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• 75% of pipes are deficient
• 40% of channels are
deficient
• 100% of culverts are
deficient
• 40% of inlets are deficient
• 70% of buildings are
potentially flood-prone

18. Hill Street SDIP
Proposed Conditions
18 | Stormwater Rehabilitation and XPSWMM October 29, 2015
Realign New
Storm System
Realign New
Storm System
System Improvements to
Reduce Flooding/Repair
Infrastructure
Increase Pipe
and Culvert Size
for System
Realign New Storm
System Along
Morehead St.
Convert Open System
to Closed System
Utility Repair/ Relocate
Throughout Project
Add Inlets Along
Morehead St. and
Throughout Project

19. Hill Street SDIP
Proposed Conditions
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• Based on nearly 20 different criteria for pipes,
channels, inlets, etc., the following improvements
are necessary:
 4.1 miles of Proposed Storm System
 459 Proposed Storm Drainage Structures
 Approximately 4000 LF of Utility Relocations

20. Hill Street SDIP
Proposed Conditions – 100yr6hr Storm
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21. Questions?
21 | Stormwater Rehabilitation and XPSWMM October 29, 2015