5. Statement of purpose
• The primary purpose is to analyze a stormwater drainage network
using EPA SWMM in comparison with the Rational Method used in
design. The pre and post developed conditions of the 23.6 acre site
have been analyzed.
• The secondary purpose is to propose alternative solutions for the
conveyance of runoff using the analysis from EPA SWMM.
6. Hypothesis
• EPA SWMM will result in a smaller discharge than the rational method
for both conditions because it accounts for infiltration and
evaporation.
7. Data collection
• Data provided by DeForest Engineering.
• CB drainage areas, lengths, and slope.
• Slope information.
• Land use areas.
• No groundwater flow (No USGS data for this area).
8. Methods
• ”As built” drawings used for analysis.
• Stormwater network:
• Stormwater network using HDPE pipes, curb inlets, head walls, and grassy
swales.
• EPA SWMM:
• Rainfall from NOAA (same storm as rational method: 10-yr 30 min)
• Infiltration using G-A
• Same peak flow geometry as rational method
• Evaporation from NOAA
• Compared pre- and post- developed conditions at same discharge
point.
9. Soil and
Rainfall
information
Clay sand, hydrologic group D
G-A parameters
from Table 4-7 of
SWMM manual
Suction head:
9.41 inches
Hydraulic
conductivity:
0.02
NOAA rainfall for 10-yr 30-min:
1.91 inches
14. Sources (will integrate citations into
presentation)
• Expert System for Calibrating Swmm C. Baffaut and J. W.
Delleur, Member, ASCE
• Automatic Calibration of the U.S. EPA SWMM Model for a Large
Urban Catchment Janet Barco; Kenneth M. Wong; and Michael K.
Stenstrom, F.ASCE
Editor's Notes
New 23.6 acre subdivision in North Louisiana by DeForest Engineering LLC.
I was one of the designers for this project in 2018.
Original design used the rational method to determine peak and total discharges to determine detention basin size.
Analysis of stormwater system using EPA SWMM.