Active Control Outlet Stormwater Design

Design of an Active Control Outlet
in a Stormwater Drainage Basin
Rose Degner, Paige Kimble, Brandon Perkins & Pa-Sweet Betancourt
Clemson University, Clemson, SC
October 20, 2020

Outline
• Introduction
• Background
• Rationale
• Objective(s)
• Approaches
• Literature Review
• Materials and Methods
• Results
• Recommendations
• Acknowledgements

Background - Climate Change
• Warming climate
• Atmosphere holds
more water
• More frequent and
more intense storms
Figure 1: 50 year trends in river discharge

Background - Impervious Surface Area
• Global population is growing
• Increase in development →
increase in impervious surface
areas
• Combination of larger storms
hitting a larger area of
impervious surfaces
• Flooding, erosion, and water
quality
Figure 2: Shape of flood hydrographs for surfaces
with varying imperviousness

Background - Small Solutions
• Larger infrastructures needed for extensive flooding
• Small changes on a universal scale
• Improve widespread water quality
• Reduce hydraulic stress on smaller receiving water bodies
• Improvements on stormwater basin outflow design
• Smaller ponds required
• More cost effective
• More effective land use
• One such improvement is the active outlet

Background - Nonpoint source pollution
• Nonpoint source pollution
• Pollution from many different sources
• Reaches water bodies
• US began legislating via the Clean Water Act and the National
Pollutant Discharge Elimination System
• One resultant technology: stormwater retention basin
• Designed to hold runoff

Background - Stormwater Retention Basins
• Main benefit: reduction in total
suspended solids (TSS)
• Also reduces runoff flow rate and
runoff volume
• How?
• Infiltration
• Runoff retention (and TSS
settling)
• Steady release of the water
• Some vegetative uptake
Insert picture of site

Background - Static Outlets
• Traditional design of
retention ponds - open
pipe outlet
• Hold water for
• Certain intensity of rain
• Set retention time
Insert diagram of retention pond

Background - Static Outlets
• Particulates/pollutants settle AS the water is released
• Not always effective for:
• More intense storms
• If field conditions change
• Water released to mimic pre-development flows
• Important to stay at or below this rate
• Static outlets are designed for average conditions
• Typically not releasing water in the most efficient manner

Background - Active Outlets
• When releasing water, can consider:
• Weather forecast
• Pond water level
• Outlet can be adjusted
• Off, on, partially open
• Maximize retention time
• Reduce outflow rates → reducing
• Total suspended solids (TSS)
• Hydraulic stress on receiving water body

Background - Active Outlets
• Larger applications
• Quebec, Paris, Detroit, and Vienna
• Used to avoid overloading sewer systems
• Have yet to be widely implemented on smaller scale
• Can increase efficiency in
• Water pollutant reduction
• Basin location
• Basin design
• Can be retrofitted onto pre-existing retention
ponds

Rationale
● Increased intensity of rain
○ Flooding concerns
○ Water quality concerns
● Active control outlets
○ Stormwater drainage is slightly more efficient
○ Improves stormwater quality
○ Possibly more cost effective
● Success of active control outlets on large scale
○ Important to consider efficacy of technology on a small scale

Objective
The objective of the project is to design and evaluate the impact of an
adaptive/active outlet control structure for stormwater management applications for
water quality and quantity benefit using a pond in Pelzer, SC as a case study.
“stormwater management” revise to include

Approaches
• Task 1. Discuss with Woolpert the extent of the project
• Task 2. Review scientific literature on engineering design related to stormwater
management
• Task 3. Apply adaptive control structure to retention pond for water quality control
• Task 4: Determine and assess the site properties (physical, hydrological, chemical)
and collect data (hydrology, topo)
• Task 5: Create site exhibits in GIS and input values for modeling
• Task 6. Develop a watershed study using EPASWMM program
• Task 7: Evaluate and compare the new models to pre existing models
• Task 8: Simulate Pre and post hydrologic conditions
• Task 9: Optimize and Design the active outlet control structure
• Task 10: Apply for permits

Deliverables
1. Logic Flowchart for Programming - Oct. 7
2. ArcGIS Map
a. Delineation of watershed draining into pond in question (Pelzer, SC) - Oct. 14
i. Important parameters for modeling (CN, tc, area, % slope, etc.)
b. Downstream impact area of outlet - Nov. 4
3. EPA SWMM Output (Storm Water Management Model)
a. One model matching previously permitted parameters (2004) - Oct. 14
b. One model for existing conditions (2020) - Oct. 14
c. One model for proposed conditions (2020)
i. Dynamic outlet by pond depth - Oct. 14
ii. Dynamic outlet by pond depth and weather forecast - Nov. 4
4. Comparison of previous and proposed discharge values for permitting - Oct 20
a. Meets project objectives and SCDHEC regulations
b. Relates to pre-development conditions
5. AutoCAD diagram of final design and instrumentation set-up - Oct. 20
6. IDEAL Model Output (Integrated Design, Evaluation, and Assessment of Loadings) - Nov. 11
a. % removal TSS
b. Supplementary water quality benefit information to SWMM
c. Tentative
7. Prototype/Proof of Concept - Nov. 11
a. Adaptive Control Structure
b. Tentative
8. References - Dec. 1

Project Management Plan &
Timeline

Task Leader Team Timeframe
[hr/person]
Literature Review Paige Kimble Everyone 80
ArcGIS Mapping Brandon Perkins 50
SWMM Rose Degner Brandon Perkins 50
Risk Assessment Paige Kimble 20
Permitting Brandon Perkins Pa-Sweet Betancourt
Rose Degner
20
Water Quality
Modeling
Rose Degner 20
Logic Map &
Programming
Paige Kimble 40
Instrumentation Pa-Sweet Betancourt 40
AutoCAD Pa-Sweet Betancourt 20
Construction &
Implementation
Pa-Sweet Betancourt Everyone 30

Literature Review - Programming
• Writing code is out of the scope of this project
• Programming Logic Controller (PLC)
• Also called a data logger
• A data logger - a point of communication
between outlet and weather forecast
programming
• CR1000x data logger from Campbell
• Ideal for outdoor conditions
• Where is the data for the program coming from?
• How is the data received and integrated into the program
• How is that programming information used by the data logger?
CR1000x Flagship Data Logger from Campbell

Programming - Where is the data coming from?
• NOAA, or the National Oceanic and
Atmospheric Administration
• Offers multiple public models
• High Resolution Rapid Refresh (HRRR) model
• Reasonable precipitation predictions
• Experimental model
• Updated hourly
• Includes cloud coverage
• Resolution of 3-km
• Forecasts up to 12h in 1-hour increments and
can extend up to 48h in 6-hour increments
insert picture of model

• Weather Prediction Center (WPC) under NOAA also
has models
• The Quantitative Precipitation Forecasts (QPF)
• Focuses on heavy rain, snow events, and flash flooding
• Forecasts in 6-, 24-, and 48-hour increments
• The WPC also offers medium-range and short-term
forecasts
• North American Mesoscale Model (NAM)
• From the National Centers for Environmental protection
• Short-term weather forecasting
• Precipitation, lightning, temperature, kinetic energy,
etc.
• Good for large storm events, such as hurricanes
insert pictures of models

• Global Forecast System (GFS)
• Provides many land and soil variables
• Includes wind, precipitation, soil
moisture, atmospheric ozone
concentration, etc.
• Covers the entire globe
• Resolution of 18 miles
• Predicts weather up to 16 days
insert picture of model

• The forecasting model used in an active control outlet program will depend on the
area of the stormwater basin, the resolution desired, the type of forecasting
desired, and potentially even the time of year. If an area is prone to flash flooding
in the summer, it may be useful to use a QPF during that time and then switch
back to using a different model for the rest of the year. As mentioned, HRRR is
sufficient for this design project, however as new models are developed and
published, the forecasting model used can be updated for the most accurate and
relevant weather predictions. Once a forecasting model has been chosen, the next
step is receiving that forecast data in a format that the program and data logger
can understand.

Programming - How is the data received and
integrated into the program?
• The weather forecasts that NOAA provides can be automated so that the forecast
is pulled from NOAA’s website with a programming code. These forecasts are
provided as a radar image, but can be received by a program as a grib file. A grib
file is a file format for the storage and transport of gridded meteorological data
(Reading GRIB Files, n.d.). The National Digital Forecast Database (NDFD) also
provides a code to decipher the grib file, known as degrib. These lines of code are
public and can be found on NOAA’s website. Thus, through this publicly available
national database, both the weather forecast in a grib file and degrib, the code to
decipher this file, can be written into a program.

Programming - How is the data received and
integrated into the program?
• Once the weather forecast has been obtained in a format that the program can
read, subcodes can be written to specify what to do with the forecast information
and any other information that is or may be collected at the site. This code can
also be written to update the forecast after a certain amount of time, such as
every fifteen minutes, so that the system can constantly be getting current
weather reports. The program being able to read the forecasting data is not
enough, however. This information ultimately needs to be sent to the data logger
so that the data logger can either open or close the stormwater basin outlet.

Programming - How is the programming
information used by the data logger?
• File and data transfer happens all the time, often without many people noticing.
When interacting with a website, for example, a computer browser will use a
protocol, HTTP, to send and receive data to and from the server that hosts that
website. A data logger can effectively be thought of as a server with its own
unique IP address. The protocol used to move files to data loggers is FTP or File
Transfer Protocol. FTP is one of the oldest and simplest protocols in use and it
allows a user to download files from or upload files to a server (Martindale, 2020).
In the case of the program written by Woolpert to gather the forecasting
information, the program is stored on a server located in an office in Dayton, OH
and it interacts with the data logger that will be located in Pelzer, SC using FTP.

Programming - How is the programming
information used by the data logger?
• So, in addition to the lines of code for getting a grib file from a weather forecasting
model, and degribbing that data, additional lines of code are written to use FTP to
send this information to the data logger. In the end, the data logger will receive
the forecasting information from the server and the real time water level from the
water level sensor. The logic program running on the data logger will then
determine if the outlet needs to be opened or closed and send the appropriate
signal to the outlet. This almost instantaneous exchanging of information between
the program and the data logger along with the logic that the program is based on
is the foundation of an active outlet control system.

Instrumentation Options
Types of valves:
• Butterfly Valve
• Globe Valve
• Ball Valve
• Pinch Valve
• Gate Valve
Types of actuators:
● Electric
● Pneumatic

Valve: Butterfly
- Butterfly valves opens, closes and regulates a fluid passage by
reciprocating about 90° with a disc type opening and closing
member
Advantages:
- Simple structure, small volume, light weight
- Small flow resistance and opening/closing time
- Low pressure drop, high pressure recovery
Disadvantages:
- Flow adjustment range is small, open 30% → flow rate 95%
- Difficult to clean
- Difficulty with slurries
- Potential for cavitation and choke

Valve: Pinch
- Pinch valves have a full-bore design. This means they can
intrinsically allow unrestricted flow and ensure complete
stoppage.
Advantages:
- Very clean, excellent drainage
- Inexpensive
- Minimal turbulence
- Low weight
- Low maintenance
Disadvantages:
- Cannot be used in high temperature applications
- Cannot be used in high pressure applications
- Cannot be used with Gas media

Valve: Ball
- Ball valve consists of a large sphere with a central hole equal to
the inside diameter of the pipe in mounted
Advantages:
- Maintains and regulates high volume - Does not require lubrication
- Superior ease of operation - Low maintenance cost
- HIgh pressure and high temp flow - Low purchase cost
Disadvantages:
- Cannot be used in high temperature applications
- Cannot be used in high pressure applications
- Cannot be used with Gas media

Valve: Gate
- Gate valves work by inserting a rectangular gate or wedge into the path
of a flowing fluid
Advantages:
- Used as shut off valve - Inexpensive
- Available in large sizes - Bi-directional
- suitable for use with slurries and viscous liquids
Disadvantages:
- Low pressure limitations - Difficult to repair
- slow open/close time - Seat and disk erosion can occur
- Poor throttling characteristics

Valve: Globe
- Globe valves have a spherical body shape with the two halves of the
body being separated by an internal baffle.
Advantages:
- Can be fast-acting
- Precise control
- Can be used in high-pressure systems
Disadvantages:
- High head loss - Not good for clean or sterile application
- Low coefficient of flow - Cantilevered mount of disk to stem
- Heavier than other valves

Actuator: Electric
- An actuator requires a control signal and a source of
energy. The control signal is relatively low and in this
case would be electric voltage or current.
Advantages:
- Fast and accurate - Very fast development times for new models
- Possible to apply sophisticated control
techniques to motion
- Relatively inexpensive
Disadvantages:
- Gear backlash limits precision - Problems of overheating in stalled conditions
- Inherently high speed with a low torque
- Brakes are needed to lock them into position

Pneumatic Actuator
- A pneumatic actuator requires a control signal and a
source of energy. The control signal is relatively low
and in this case would be pressurized air
Advantages:
- Low cost
- Ease at reversion movement
- High speed of moving
- Ecological purity
- Explosion and fire safety
Disadvantages:
- Compressibility of air
- Problems of overheating in stalled conditions
- Impossibility to receive uniform air output
- Difficulties in performance at slow speed and
constant speed of the working bodies movement
- Requires good preparation
- Brakes are needed to lock them into position

Greenville County Regulations
TSS & basin design criteria
Coming soon...

1. ArcGIS ArcMap 10.8
2. Lucidchart.com
3. EPA SWMM 5.1
1. Basin Delineation &
Characterization
2. Programming Logic
3. Risk Assessment
4. Modeling
Materials Methods

ArcGIS ArcMap 10.8
• ArcMap is used to display geographic information as a
collection of layers and other elements in a map view
• The data frame provides a geographic window that allows the
user to display and work with geographic information as a
series of map layers
• These layers can also be used to store data relevant to the
project such as:
• Soil Data
• Digital Elevation
• Geometric Values (Area, Length)
• ArcMap also has the ability to perform geoprocessing
operations to assist in calculating necessary input values for
modeling https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.arcgismastery.com%2Fp%2Farcgis-desktop-
arcmap&psig=AOvVaw3Wk727VIKA7mCInVKKbb3i&ust=1602257572321000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCPjCquCopewCFQAAA
AAdAAAAABAD

Basin Delineation
● Basin delineation exhibits are used for overall
visualization of all stormwater drainage being deposited
into the pond via overland flow or pipe network
(through yard inlets/junction boxes)
○ 2004 delineation based on 2004 Woolpert area
values
○ Current conditions delineation
● The layers present in this view include:
○ Landsat 8 Basemap Imagery: Provides satellite view of
the area of study
○ USGS Topo Map: Provides topographic information for
delineation of basin & subcatchments
○ Digital Elevation Model: Provides point coverage
elevation data that is compiled into a raster file which
displays a connected elevation cover of the land (light
green=low elevation to red/white=high elevation) used for
delineation of the basin/subcatchments
○ Basin .shp file: Shows delineation of basin for area of
study (also provides area through geometric calculation)

Land Cover
● Land cover exhibits are used to show the land cover
classifications of the basin that will be used in the
determination of subcatchment curve numbers
○ 2004 land cover based on previous delineation
○ Current conditions land cover
the area of study
○ Land Cover .shp file: Shows land cover classification of
basin area (also provides areas through geometric
calculations)
study

Soils
● Soils exhibits are used to show the soil types and
hydraulic classifications in the watershed that will be
used in the determination of subcatchment curve
numbers
○ 2004 soils based on previous delineation
○ Current conditions soils
the area of study
○ Soils .shp file: Shows the soil types and hydraulic
classifications in the basin area (also provides areas
through geometric calculations)
study

Subcatchments
● Subcathment exhibits are used for overall visualization
of all subcatchment divisions within the Pelzer Pond
Basin
○ 2004 subcatchments based on previous basin
delineation
○ Current conditions subcatchments
○ Landsat 8 Basemap Imagery: Provides satellite view of the
area of study
○ Digital Elevation Model: Provides point coverage elevation
data that is compiled into a raster file which displays a
connected elevation cover of the land (light green=low
elevation to red/white=high elevation) used for delineation of
the basin/subcatchments
○ Subcatchments .shp file: Shows delineation of subcatchments
(divided by node method) within basin (also provides area
through geometric calculation)
○ Basin .shp file: Shows delineation of basin for area of study
(also provides area through geometric calculation)

Link Node
● Link Node exhibits are used to show the existing inlet structures
and the pipe linkages connecting them to each other and the
pond
○ 2004 links and nodes based on previous delineation
○ Current conditions links and nodes
○ Landsat 8 Basemap Imagery: Provides satellite view of the area
of study
○ Digital Elevation Model: Provides point coverage elevation data
that is compiled into a raster file which displays a connected
elevation cover of the land (light green=low elevation to
red/white=high elevation) used for delineation of the
basin/subcatchments
(divided by node method) within the basin (also provides area
○ Node .shp file: Shows the location of inlet structures (white) within
the basin
○ Link .shp file: Shows the piping (green) connecting the inlet
structures to each other and the pond (also provides length through
geometric calculation)
○ Basin .shp file: Shows delineation of basin for area of study (also
provides area through geometric calculation)

Tc & Slope
● Tc & Slope exhibits are used to show the existing inlet structures and the
pipe linkages (as well as length) connecting them to each other and the
pond
○ 2004 Tc & Slope based on previous delineation
○ Current conditions Tc & Slope
○ Landsat 8 Basemap Imagery: Provides satellite view of the area
of study
○ Digital Elevation Model: Provides point coverage elevation data
that is compiled into a raster file which displays a connected
elevation cover of the land (light green=low elevation to
red/white=high elevation) used for delineation of the
watershed/subcatchments
(divided by node method) within the basin (also provides area
○ Node .shp file: Shows the location of inlet structures (white) within
the basin
○ Tc_Slope .shp file: Shows the overland flow path (orange) from
highest, furthest elevation in the subcatchment from the inlet
structure to the inlet structure (also provides length through
geometric calculation; provides slope input elevation using
endpoints)
○ Basin .shp file: Shows delineation of basin for area of study (also
provides area through geometric calculation)

Current/Proposed Model Inputs from ArcMap

Materials and Methods - Programming Logic
• Many inputs to consider in programming
• Ex. current water level, precipitation forecasts, and local regulations on how
long water can be held in pond
• Logic flowchart was made to visualize
• On/off system was assumed
• Flowchart can be expanded for partially opening valve

Logic
Flowchart
Figure: Flow chart demonstrating
the logic of active outlet system

Materials and Methods - Risk Assessment
To be completed
Would this be better in materials and methods or in the literature
review?

EPA SWMM 5.1
• Water quantity and quality
modeling for urban watersheds
• Models stormwater runoff by
the curve number method

Modeling an Autonomous Outlet
By Depth
1. Find freeboard threshold depth of
collection pond
2. Manipulate Control Options by
If/Then Statements
3. Set time to open/close orifice

Modeling an Autonomous Outlet
By Forecasting
1. Open outlet properties and set tide
gate to “YES”
2. Create a rain gage time series
3. Find runoff at each time increment
4. Calculate volume of water in the
pond at each time increment
5. Manipulate tailwaters time series by
storage capacity and forecasted
runoff
High tailwaters
Low tailwaters

Active Control Outlet Stormwater Design

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