HomeMy Public PortalAbout2005 - Stormwater Master Plan - Phase 4 - Mo River and Algoa StudyMissouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005
Comprehensive
Stormwater
Master Plan Update
Phase 4: Missouri
River & Algoa Study
Area Report
for the
City of Jefferson, Missouri
Prepared by:
Burns & McDonnell
Project Number 36505
9400 Ward Parkway
Kansas City, Missouri 64114-3319
Tel: 816 333-9400
www.burnsmcd.com
November 18, 2005
Mr. Pat Sullivan
City of Jefferson Community Development
City Hall
320 East McCarty Street
City of Jefferson, Missouri 65101
Comprehensive Stormwater Management Plan Update,
Phase 4: Missouri River and Algoa Study Area Report
FINAL SUBMITTAL
Burns & McDonnell Project No. 36505
Dear Mr. Sullivan,
Burns & McDonnell Engineering is pleased to present this draft submittal of
the City of Jefferson’s Comprehensive Stormwater Master Plan Update,
Phase 4: Missouri River and Algoa Study Area Report.
It has been a pleasure working with you and your staff on this project, and we
look forward to continued work with your City.
If we can be of further assistance, please do not hesitate to call.
Best Regards,
Galen Miller, P.E.
Project Manager
Enclosed: Ten Report Binders
Ten CD-ROM Electronic Reports
Missouri River and Algoa Study Area Stormwater Management Plan
City of Jefferson, Missouri
CITY OF JEFFERSON, MISSOURI
COMPREHENSIVE STORMWATER MASTER PLAN UPDATE PHASE 4:
MISSOURI RIVER AND ALGOA STUDY AREA REPORT
B&McD Project No. 36505
INDEX AND CERTIFICATION PAGE
REPORT INDEX
Section Description Page
Number
of Pages
ES Executive Summary ES-1 3
1 Introduction 1 3
2 Data Collection 4 2
3 Hydrologic Modeling 6 8
4 Hydraulic Modeling 14 8
5 Existing System Performance 22 7
6 Recommendations 29 20
7 Glossary of Terms 49 5
Appendix A XP-SWMM Runoff (Hydrologic) Results 4
Appendix B XP-SWMM Surcharging Tables 2
Appendix C HEC-RAS Results for Existing Conditions 20
Appendix D HEC-RAS Results for Future Conditions 20
Appendix E Exhibits 12
I hereby certify, as a Professional Engineer in the State of Missouri, that the information in this document was
assembled under my direct responsible charge, and is based on information and data that was available and obtained
from the sources described herein. The Engineer cannot be held responsible for added or deleted information once
distributed.
CERTIFICATION
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 i
Missouri River and Algoa Study Area Report
City of Jefferson, Missouri
TABLE OF CONTENTS
EXECUTIVE SUMMARY........................................................................................................ES-1
GENERAL INFORMATION..............................................................................................................ES-1
METHODOLOGY..............................................................................................................................ES-1
Data Collection...........................................................................................................................................................ES-1
Hydrology...................................................................................................................................................................ES-1
Hydraulics...................................................................................................................................................................ES-1
SUMMARY OF RECOMMENDATIONS...........................................................................................ES-2
SECTION 1.0 - INTRODUCTION.................................................................................................1
1.1 PROJECT TEAM..............................................................................................................................1
1.2 STUDY AREA...................................................................................................................................1
1.3 PURPOSE.........................................................................................................................................1
1.4 SCOPE OF SERVICES....................................................................................................................1
1.4.1 Information Review.................................................................................................................................................2
1.4.2 Field Investigations and Inventory...........................................................................................................................2
1.4.3 Existing System Evaluation.....................................................................................................................................2
1.4.4 Watershed Mapping.................................................................................................................................................2
1.5 INFORMATION PROVIDED BY CLIENT.........................................................................................2
SECTION 2.0 - DATA COLLECTION...........................................................................................4
2.1 DATUM AND PROJECTION INFORMATION.................................................................................4
2.2 MAPPING SOURCES......................................................................................................................4
2.3 FIELD INVESTIGATIONS................................................................................................................4
2.3.1 Major Structures (Bridges/Culverts)........................................................................................................................5
2.3.2 Minor Structures......................................................................................................................................................5
2.4 PROJECT PHOTOGRAPHS ............................................................................................................5
2.5 OTHER SOURCES OF INFORMATION..........................................................................................5
SECTION 3.0 - HYDROLOGIC MODELLING..............................................................................6
3.1 INTRODUCTION..............................................................................................................................6
3.2 WATERSHED DELINEATION.........................................................................................................6
3.2.1 Subarea Boundaries..................................................................................................................................................6
3.3 PRECIPITATION..............................................................................................................................6
3.3.1 General.....................................................................................................................................................................6
3.3.2 Rainfall Distribution................................................................................................................................................6
3.3.3 Rainfall Depths........................................................................................................................................................7
3.3.4 Rainfall Duration......................................................................................................................................................7
3.4 RUNOFF...........................................................................................................................................8
3.4.1 Soils.........................................................................................................................................................................8
3.4.2 Land Use..................................................................................................................................................................8
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 ii
3.4.3 Loss Method...........................................................................................................................................................10
3.4.4 Subarea Lag Time..................................................................................................................................................10
3.4.5 Time of Concentration...........................................................................................................................................10
3.4.6 Hydrographs...........................................................................................................................................................11
3.4.7 Conveyance Routing..............................................................................................................................................11
3.5 MODEL CALIBRATION.................................................................................................................11
3.5.1 APWA 5600 Rational Method...............................................................................................................................12
3.5.2 Conclusion.............................................................................................................................................................13
SECTION 4.0 - HYDRAULIC MODELLING...............................................................................14
4.1 INTRODUCTION............................................................................................................................14
4.2 DIGITAL TERRAIN MODEL...........................................................................................................15
4.3 STREAM NETWORK.....................................................................................................................15
4.4 CROSS-SECTION CUT-LINES......................................................................................................15
4.5 MANNING’S “n” VALUES.............................................................................................................16
4.6 BRIDGES AND CULVERTS..........................................................................................................16
4.6.1 Cross Sections........................................................................................................................................................17
4.6.2 Bridge Deck / Roadway.........................................................................................................................................17
4.6.3 Modeling Approach...............................................................................................................................................17
4.6.4 Internal Bridge Cross Sections...............................................................................................................................17
4.7 INEFFECTIVE FLOW AREAS .......................................................................................................17
4.8 EXPANSION AND CONTRACTION COEFFICIENTS...................................................................17
4.9 FLOW DATA...................................................................................................................................18
4.9.1 Profiles...................................................................................................................................................................18
4.9.2 Flow Change Locations..........................................................................................................................................18
4.9.3 Boundary Conditions.............................................................................................................................................18
4.9.4 Flow Conditions.....................................................................................................................................................18
4.9.5 Detention / Storage.................................................................................................................................................19
4.10 FLOODWAY ANALYSIS..............................................................................................................19
4.11 CALIBRATION.............................................................................................................................19
4.11.1 Previous Studies...................................................................................................................................................19
4.11.2 Stormwater Questionnaire....................................................................................................................................19
4.12 QUALITY CONTROL / DEBUGGING..........................................................................................19
4.13 Digital Models..............................................................................................................................20
SECTION 5.0 - EXISTING SYSTEM PERFORMANCE.............................................................22
5.1 Missouri River and Algoa District Study Area...........................................................................22
5.1.1 Land Use................................................................................................................................................................22
5.1.2 Hydrologic Summary.............................................................................................................................................22
5.1.3 Existing Drainage System......................................................................................................................................24
5.2 EVALUATION CRITERIA...............................................................................................................25
5.3 DRAINAGE SYSTEM PERFORMANCE........................................................................................25
5.3.1 Major Structure Modeling Results from HEC-RAS...............................................................................................26
5.3.2 Minor Structure Modeling Results - Surcharging..................................................................................................27
SECTION 6.0 - RECOMMENDATIONS......................................................................................29
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 iii
6.1 INTRODUCTION............................................................................................................................29
6.2 SURVEYOR'S OBSERVATIONS...................................................................................................29
6.3 EVALUATION OF PRIORITIES.....................................................................................................30
6.3.1 Methodology..........................................................................................................................................................30
6.3.2 Priority Definitions................................................................................................................................................30
6.4 Cost Opinions for Projects..........................................................................................................32
6.5 PROJECT 1 – Main St. & Circle Dr. (City Project).....................................................................33
6.5.1 Description.............................................................................................................................................................33
6.5.2 Recommended Improvement.................................................................................................................................33
6.5.3 Cost Opinion..........................................................................................................................................................34
6.5.4 Priority...................................................................................................................................................................34
6.6 PROJECT 2 – High Street & Benton Street (City Project)........................................................35
6.6.1 Description.............................................................................................................................................................35
6.6.2 Recommended Improvement.................................................................................................................................35
6.6.3 Cost Opinion..........................................................................................................................................................35
6.6.4 Priority...................................................................................................................................................................35
6.7 PROJECT 3 – Allen Drive (City Project).....................................................................................37
6.7.1 Description.............................................................................................................................................................37
6.7.2 Recommended Improvement.................................................................................................................................37
6.7.3 Cost Opinion..........................................................................................................................................................37
6.7.4 Priority...................................................................................................................................................................37
6.8 PROJECT 4– Delta Place & Riverwood Drive (City Project)....................................................39
6.8.1 Description.............................................................................................................................................................39
6.8.2 Recommended Improvement.................................................................................................................................39
6.8.3 Cost Opinion..........................................................................................................................................................40
6.8.4 Priority...................................................................................................................................................................40
6.9 PROJECT 5 – State Street & Marshall Street (City Project).....................................................41
6.9.1 Description.............................................................................................................................................................41
6.9.2 Recommended Improvement.................................................................................................................................41
6.9.3 Priority...................................................................................................................................................................41
6.10 PROJECT 6– Algoa District (City Project)...............................................................................42
6.10.1 Description...........................................................................................................................................................42
6.10.2 Recommended Improvement...............................................................................................................................42
6.10.3 Priority.................................................................................................................................................................42
SECTION 7.0 - GLOSSARY OF TERMS...................................................................................49
7.1 DEFINITIONS.................................................................................................................................49
7.2 ACRONYMS...................................................................................................................................52
APPENDIX A – XP-SWMM HYDROLOGIC RUNOFF RESULTS
APPENDIX B – XP-SWMM SURCHARGING RESULTS
APPENDIX C – HEC-RAS RESULTS, EXISTING CONDITIONS
APPENDIX D – HEC-RAS RESULTS, FUTURE CONDITION
APPENDIX E – EXHIBITS
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 iv
Exhibit 1 Missouri River Study Area
Exhibit 2 Hydrologic Modeling Data
Exhibit 3 Soils Data
Exhibit 4 Existing Conditions Land Use Plan
Exhibit 5 Future Conditions Land Use Plan
Exhibit 6 Existing and Future 100-year Floodplains and Hydraulic Modeling Data
Exhibit 7 XPSWMM Hydraulic Modeling Data
Exhibit 8A, 8B, 8C Surcharging in XPSWMM
LIST OF TABLES
Table ES-1 Summary of Recommendations...............................................................................ES-2
Table 3-1 Rainfall Depths for City of Jefferson, Missouri................................................................7
Table 3-2 Runoff Coefficients.............................................................................................................9
Table 3-3 Small Subshed Flow Comparison...................................................................................12
Table 4-1 Summary of Missouri River Study Area HEC-RAS Model.............................................14
Table 4-2 Data Development.............................................................................................................14
Table 4-3 Manning’s Roughness Coefficients ................................................................................16
Table 4-4 Expansion and Contraction Coefficients........................................................................18
Table 4-5 HEC-RAS Models...............................................................................................................20
Table 4-6 XP-SWMM Models.............................................................................................................21
Table 5-1 Land Use Breakdown for Moreau River South...............................................................22
Table 5-2 Hydrologic Characteristics of Moreau River South.......................................................23
Table 5-3 Existing Design Criteria, Culverts...................................................................................24
Table 5-4 Existing Design Criteria, Open Channels.......................................................................24
Table 5-5 HEC-RAS Analysis of Major Structures..........................................................................26
Table 6-1 HEC-RAS Analysis of Major Structures..........................................................................30
LIST OF FIGURES
Figure ES-1 Project Locations.......................................................................................................ES-3
Figure 3-1 SCS Rainfall Distribution...................................................................................................7
Figure 6-1 Project 1 Main St. & Circle Dr..........................................................................................43
Figure 6-2 Project 2 High St. and Benton St....................................................................................44
Figure 6-3 Project 3 Allen Dr..............................................................................................................45
Figure 6-4 Project 4 Delta Pl. & Riverwood Dr.................................................................................46
Figure 6-5 State St. & Marshall St......................................................................................................47
Figure 6-6 Algoa District....................................................................................................................48
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 ES-1
EXECUTIVE SUMMARY
GENERAL INFORMATION
Burns & McDonnell Engineering Company was authorized by the City of Jefferson, Missouri to study
areas of the Missouri River watershed within the city limits that had not been examined in previous
studies (see Exhibit 1). These included three small areas on the south bank of the Missouri River that
drain directly to the river without entering another creek, and a district known as the Algoa Area.
Different portions of the Algoa Area drain to Rising Creek, the Osage River, and the Moreau River. The
main stems of the Missouri River, the Moreau River, and the Osage River are excluded from the analyses
that were conducted for this report.
The area studied included approximately 7.98 square miles of drainage (5,107 acres). The Missouri River
and Algoa Study Area Report is part of the fourth and final phase of the City of Jefferson Stormwater
Master Plan.
The purpose of this study is to perform a hydrologic analysis of this area under existing and future
development conditions, and a hydraulic analysis of the stormwater drainage system. The results of these
analyses have allowed floodplains to be drawn for these areas, and for culvert and pipe flow demands to
be better understood.
METHODOLOGY
Data Collection
Data about the watershed was collected in a geographically referenced database, ESRI’s Geographical
Information System (GIS) mapping software. This information was used to generate the input and store
the output from XP-SWMM 2000 stormwater modeling software and the U.S. Army’s Corps of Engineers
HEC-RAS river analysis program. The GIS database serves as both an inventory of the stormwater
system and an easily accessible repository of the results of this study.
Hydrology
The watershed was classified for soil type, vegetative cover, current, and future land use and divided into
subsheds. Hypothetical storms with return periods from two to one hundred years were used to simulate
stormwater runoff and generate flow hydrographs from each subshed for both existing and future land use
conditions. A FEMA approved hydrologic modeling software, XP-SWMM2000 was used to perform
these analyses.
Hydraulics
Routing of the runoff hydrographs through culverts and pipe systems was computed, and peak flows were
evaluated in the major channels and large culverts of the watershed to calculate water surface elevations.
Floodplains were then drawn for the 100-year existing and future conditions. XP-SWMM2000, the U.S.
Army Corps of Engineer’s HEC-RAS river analysis software, and GIS were used for these tasks.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 ES-2
SUMMARY OF RECOMMENDATIONS
Recommendations were developed for those conveyance structures that posed an immediate or future
safety concern, or were identified by the City or County as priority projects. The objective of the
recommendations is to provide planning level solutions. However not all of the recommendations suggest
improvements. The large number of recently built, surcharging structures in the Algoa Area do not
warrant recommendations for replacement, but should be carefully monitored for maintenance activities
and new development in upstream areas. Many of these surcharging structures are privately owned or
owned by the state of Missouri.
Based on modeling studies and input from the City, the flooding problems identified in this study were
grouped into projects. Two of these projects are not prioritized because no recommendation for City
action is made, but they are included to suggest areas where further development must proceed
cautiously, and maintenance activities should be systematic.
Table ES-1 summarizes these projects.
Table ES-1
Summary of Recommendations
Project Location Description
Construction
Cost Priority
1 City Main St. & Circle Dr.
Upsize 190’ of pipe $100,449 HIGH
2 City High St. & Benton Dr.
Upsize 843’ of pipe $341,804 HIGH
3 City Allen Dr.
Upsize 268’ of pipe $131,749 MEDIUM
4 City Delta Pl. & Riverwood Dr.
Upsize 115’ of pipe $94,366 LOW
5 City State St. & Marshall Dr. ------ REVIEW DURING FUTURE
DEVELOPMENT
6 City Algoa Area ------ REVIEW DURING FUTURE
DEVELOPMENT
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 1
SECTION 1.0 - INTRODUCTION
In the year 2001, the City of Jefferson embarked on a program to develop stormwater master plans for
each of the City’s major watersheds. This program is based on a recognized need to upgrade existing
inadequate stormwater conveyance systems and to plan for new systems in developing areas. The
economic well being of the City depends on its ability to attract and retain business and industry as well
as residents to live in the City. Part of the City’s ability to attract business and residents depends on its
ability to provide adequate services such as drinking water, sewers, transportation and stormwater
management.
Historically, stormwater management has only been a concern when major floods occur. With increased
development and the associated increases in impervious area due to development, the volume of runoff
from rainfall and the frequency of flooding have correspondingly increased. This has caused the City to
focus its attention on the need to provide improved stormwater management facilities in all areas of the
City.
1.1 PROJECT TEAM
Burns & McDonnell Engineering was the prime contractor for this study. Central Missouri Professional
Services, Inc. conducted the field surveys.
Burns & McDonnell Engineering
9400 Ward Parkway
Kansas City, Missouri 64114
phone: (816) 333-9400
Project Manager: Galen Miller, PE
Central Missouri Professional Services
2500 East McCarty Street
Jefferson City, Missouri 65101
phone: (573) 634 3455
Contact: Keith Brickey
1.2 STUDY AREA
The areas studied for this phase of this report include the Missouri River Study Area and the Algoa Area
(see Exhibit 1). The Missouri River Study Area represents three small watersheds that drain to the
Missouri River without entering another named tributary. The Algoa Area represents a large area that is
predominantly part of an annexation that occurred in November 2003. This area drains to the Missouri
River via the Moreau River, Osage River and Rising Creek. However the main stems of these waterways
are specifically excluded from the analysis. Together, these areas represent about 7.98 square miles of
drainage area.
1.3 PURPOSE
The Missouri River and Algoa Study Area Report is part of the fourth and final phase of the City of
Jefferson Stormwater Management Plan. The purpose of this study is to model existing and future
surface conditions and the ability of the storm drainage system to convey the runoff from various events.
1.4 SCOPE OF SERVICES
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 2
This report presents a description of the services completed for the hydrologic and hydraulic modeling
under existing and future surface conditions for the Missouri River and Algoa Study Area watersheds.
The report will include supporting text, tables, figures, exhibits, computer models, computer output and
appendices to accurately present the services completed. The following major tasks are included in this
study:
1.4.1 Information Review
A comprehensive review of the existing information and studies provided an understanding of existing
conditions and the improvement plans previously proposed and/or implemented. This task involved the
assemblage, review and organization of existing mapping, records, reports, ordinances, criteria and
floodplain studies available from the City, County and other sources.
1.4.2 Field Investigations and Inventory
A survey of the watersheds and drainage system was conducted within the study area. The purpose of
this field investigation was to obtain specific information on existing piping systems, channels and
structures. Observations were recorded in a standardized format and supplemented with photographic
records. Data gathered included the following items:
• Measurement of hydraulic parameters
• Logging of information in a GIS-compatible format.
1.4.3 Existing System Evaluation
Hydrologic and hydraulic models were developed for drainage system components (structures and/or
natural and improved channels) beginning where 24 inch or larger culverts were in place. The stormwater
system was evaluated under the following two (2) conditions:
• Existing conditions with the existing storm sewer system – This plan represents
conditions as currently observed within the watershed.
• Future surface conditions with the existing storm sewer system – This plan
represents fully urbanized conditions in the watershed without changes to the existing
sewer system.
1.4.4 Watershed Mapping
The FEMA Flood Insurance Study was published October 6, 1981. Since that time, the watershed has
experienced considerable urbanization. Additionally, advances in hydrologic and hydraulic modeling, the
introduction of Geographical Information Systems (GIS) and new aerial topography allow a more
accurate representation of floodplains.
For this study new floodplains were developed for the 100-year storm event for existing and future
surface conditions. It was not within the scope of this study to prepare a FEMA map revision.
1.5 INFORMATION PROVIDED BY CLIENT
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 3
In the preparation of this report, the information provided by the Client was used to make certain
assumptions with respect to conditions which may exist in the future. While Burns & McDonnell believes
the assumptions made are reasonable for the purposes of this report, Burns & McDonnell makes no
representation that the conditions assumed will, in fact, occur. In addition, while Burns & McDonnell has
no reason to believe that the information provided by the Client, and on which this report is based, is
inaccurate in any material respect, Burns & McDonnell has not independently verified such information
and cannot guarantee its accuracy or completeness. To the extent that actual future conditions differ from
those assumed herein or from the information provided to Burns & McDonnell, the actual results will
vary from those forecast.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 4
SECTION 2.0 - DATA COLLECTION
2.1 DATUM AND PROJECTION INFORMATION
Mapping data was provided by the City in GIS format referenced to the following datum and projection
information:
Horizontal Datum: 1983 North American Horizontal Datum (NAD83)
Vertical Datum: North American Vertical Datum 1988 (NAVD88)
Coordinate System: Missouri Central State Plane (FIPS Zone 2402 - Feet)
2.2 MAPPING SOURCES
• Topography – 2-foot contour interval
• Mass Points and Break Lines
• Aerial Photography
• Planimetrics
• Soils Information – Soil mapping from the University of Missouri Spatial Data
Information Service (MSDIS)
• Land Use / Land Planning (Zoning)
2.3 FIELD INVESTIGATIONS
Elevation and location surveys of the stormwater drainage system were conducted in conjunction with
this study. Surveys collected the hydraulic data for drainage structures within the study area identified by
the Engineer, City and County Staff. Significant drainage structures were generally identified by the
following criteria:
• 24 inch diameter (or equivalent capacity) or larger.
• Major structures (bridge or culvert) having tributary areas of 160 acres or greater.
• Hydraulic structures within close proximity of buildings or other significant land objects.
• Other structures of interest identified by City and County staff.
A combination of Global Positioning Systems (GPS) and total station technology was used to obtain the
required elevations for surveyed structures. Elevation information was collected using a data collector.
Additional information, such as shape, material, condition, type, etc. was recorded on standardized forms.
The data collected at the various types of drainage structures is listed below.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 5
For those structures that were not surveyed, but are part of the modeled conveyance system, openings
were measured and inverts approximated from the available topography.
2.3.1 Major Structures (Bridges/Culverts)
• Upstream channel cross-sections
• Structure opening dimension information
• Low chord and top of road elevations
• Top centerline elevation section to define weir flow overtopping the structure
• X, Y, and Z coordinate information
• Digital photographs consisting of upstream face, looking upstream, downstream face,
and looking downstream
2.3.2 Minor Structures
• Structure opening dimension information
• Overtopping elevations controlling the roadway's level of service
• Construction material and condition
• Other unusual or pertinent information
• Digital photographs
2.4 PROJECT PHOTOGRAPHS
As part of the scope of the project, digital photographs were taken of each hydraulic structure (i.e.
bridges, culverts, and inlets, etc.) studied during the project. Project photographs are included in this
report as digital files.
2.5 OTHER SOURCES OF INFORMATION
In addition to the information described above, several other sources of information were consulted
during completion of the project:
• Q3 floodplain boundaries – FEMA
• Flood Insurance Rate Maps (FIRM’s) – FEMA
• Flood Insurance Study (FIS) – FEMA
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 6
SECTION 3.0 - HYDROLOGIC MODELLING
3.1 INTRODUCTION
The hydrologic analysis for this study was done using XP-SWMM2000 stormwater management
modeling software (Version 8.52) from XP Software Incorporated. The software generates runoff
hydrographs at desired locations in the watershed for specific storm events based on the specific input
parameters for each component of the process. For this study, the RUNOFF module was used to generate
hydrographs for return periods of 2, 5, 10, 25, 50 and 100 years. Parameters used in the hydrologic
modeling include the Soil Conservation Service’s (SCS) Type II hypothetical storm generated from
rainfall frequency data for precipitation, the SCS curve number for the loss rate, the SCS dimensionless
unit hydrograph, and physical characteristics of each subshed.
3.2 WATERSHED DELINEATION
3.2.1 Subarea Boundaries
The watersheds were divided into sub watershed areas, or subsheds. These subsheds are based on
hydrologic and/or hydraulic features, such as terrain, channels, confluences, and culverts or bridges
within the Missouri River Study Area. Exhibit 2 shows the subsheds associated with the Missouri River
and Algoa Study Area watersheds. Each subshed was assigned a unique identifier in the hydrologic
model.
3.3 PRECIPITATION
3.3.1 General
Every storm event that occurs within a watershed is unique. Some storms are short and intense and
deposit a large amount of rainfall in a short period of time. Other storms have a constant rainfall intensity
that occurs over a long period of time. Because there is no means to predict the characteristics of a given
storm, a synthetic or design storm is typically used for hydrologic modeling. A design storm is simply an
assumed distribution of rainfall over a given amount of time.
3.3.2 Rainfall Distribution
For this study, a Soil Conservation Service (SCS) Type II rainfall distribution was used. The SCS
distribution was prepared for use in the United States for storms of 6 and 24-hour durations. The Type II
storm distribution is applicable to central Missouri. The distribution of rainfall is shown in Figure 4-1.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 7
3.3.3 Rainfall Depths
Technical Paper No. 40 Rainfall Frequency Atlas of the United States (TP-40) was used to determine the
rainfall depths for various storm recurrence periods and various time periods. The TP-40 based data is
shown in Table 4-1 below:
Table 3-1
Rainfall Depths for City of Jefferson, Missouri
Depth (inches)
Time 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr
5 min 0.45 0.54 0.6 0.69 0.77 0.84
10 min 0.71 0.87 0.98 1.14 1.27 1.4
15 min 0.89 1.1 1.24 1.45 1.62 1.78
30 min 1.19 1.5 1.71 2.02 2.26 2.5
1 hr 1.5 1.92 2.2 2.61 2.93 3.25
2 hr 2 2.5 2.9 3.3 3.75 4.2
3 hr 2.25 2.75 3.25 3.75 4.15 4.65
6 hr 2.65 3.3 3.85 4.45 4.9 5.55
12 hr 3.25 3.85 4.55 5.2 5.8 6.55
24 hr 3.5 4.55 5.35 6.1 6.7 7.5
3.3.4 Rainfall Duration
The design storm used in the analysis of a drainage system is the pattern of rainfall over a specific
duration for a given return period. The duration that puts the greatest demand on the system is termed the
SCS Rainfall Distribution
0%
20%
40%
60%
80%
100%
0%20%40%60%80%100%
Percent of Storm Duration
Cu
m
m
u
l
a
t
i
v
e
P
e
r
c
e
n
t
o
f
Ra
i
n
f
a
l
l
Figure 3-1
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 8
“critical storm duration” and is roughly equal to the time of concentration of the watershed. Time of
concentration, Tc, is the time at which the entire drainage area begins to contribute runoff. It may also be
defined as the time required for runoff to flow from the farthest point in the watershed to the outlet. The
“critical” duration represents the minimum time required to insure that runoff from all parts of the
drainage area is included in the peak discharge measured at the outlet. The design storm duration used in
this project was the 6-hour storm for all return periods.
3.4 RUNOFF
3.4.1 Soils
NRCS soils information used for calculating hydrologic parameters was obtained in an electronic format
from the Missouri Spatial Data Information Service (MSDIS)1. According to the source, soil scientists
manually compiled field maps on 1:24000 scale one-third-quadrangle ortho-photography in the 1927
North American Datum (see Exhibit 3).
3.4.2 Land Use
3.4.2.1 Existing Conditions
In order to determine the parameters needed for the hydrologic model, a land use map was developed for
the watershed (see Exhibit 4). Land use parameters influencing runoff were estimated from aerial
photography and field observations. The curve numbers shown in Table 4-2 were taken from TR-55,
Urban Hydrology for Small Watersheds2. Curve numbers represent antecedent moisture condition II.
1 University of Missouri, Department of Geography, Missouri Spatial Data Information Service,
http://msdis.missouri.edu/
2 U.S. Department of Agriculture, Natural Resource Conservation Service, Conservation Engineering Division,
Urban Hydrology for Small Watersheds, Technical Release 55, June 1986.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 9
Table 3-2
Runoff Coefficients
Cover Type / Land Use Curve Numbers for Hydrologic
Soil Group
A B C D
Agricultural 60 72 80 84
Brush 30 48 65 73
Commercial 89 92 94 95
Floodplain 60 72 80 84
High Density Residential 77 85 90 92
Impervious Area 98 98 98 98
Industrial 81 88 91 93
Low Density Residential 54 70 80 85
Meadow & Pasture 39 61 74 80
Medium Density Residential 61 75 83 87
Parks & Open Space 39 61 74 80
Public & Semi Public 77 85 90 92
Right of way 68.5 79.5 86 89
Steep (too steep for development) 30 48 65 73
Wooded Areas 30 55 70 77
3.4.2.2 Future Surface Conditions
Hydrologic parameters for the future surface condition were based on planning information provided by
the City and engineering judgment (see Exhibit 5). Several areas were assigned land uses equivalent to
their proposed zoning designation. Additional criteria used to fill out the future surface condition map are
as follows:
• Adjacent to state routes, a 330 foot strip on each side of roadways defined as commercial.
• Adjacent to major intersections involving state routes or major arterials, a 660 foot strip on each
side of each intersecting roadway defined as commercial while extending 660 foot in all
directions from the intersection.
• For large contiguous areas that have been developed with multiple residential properties, define
these areas as residential (low, medium or high density where appropriate).
• For existing or developing subdivision areas, define with no change for the future surface
condition.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 10
• On presently undeveloped ground, defined as undeveloped if in a flood plain, if too steep to
develop (delineated when an acre or more is steeper than 15%), or zoned as open space, park or
recreational. In all other cases, define as low or medium residential, or commercial or industrial
based on the area proposed zoning (in those areas outside of the City but within the proposed
annexation area).
3.4.3 Loss Method
The SCS Curve Number Loss Method was utilized according to the technical guidelines prescribed by the
TR-55 Manual. Based on the combinations of soils types and land use characteristics shown in Table 4-
2, a weighted runoff curve number was estimated for each subarea. This was done by subdividing each
subarea into polygons representing every combination of land use and soils type. With a curve number
assigned to each polygon, a weighted curve number was calculated for the entire subarea as follows.
Weighted Curve No. = ∑(Ai x CNi) / ∑AI
Where
Ai = area of each shape
AI = area of the subarea, acres
CNi = Curve No. assigned to a given polygon
3.4.4 Subarea Lag Time
For each subarea, a lag time was estimated using the SCS lag equation:
Where: TL = lag, hrs
L = length of mainstream to farthest divide, ft
S = potential maximum retention, in (1000 / CN – 10)
CN = SCS curve number
Y = average slope of watershed, %
3.4.5 Time of Concentration
For each subarea, a time of concentration was calculated based on the following SCS relationship:
Where: TL = lag time, hrs
TC = time of concentration, hrs
()
5.0
7.08.0
1900
1
Y
SlTL
+=
CLTT6.0=
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 11
3.4.6 Hydrographs
For each subarea, a flow hydrograph was calculated using the SCS dimensionless curvilinear unit
hydrograph method.
3.4.7 Conveyance Routing
XP-SWMM performs hydraulic flow routing for open channel and/or closed conduit systems. This
software is a modified and FEMA approved version of EPASWMM v.4.4h. The Hydraulic module
receives hydrograph input from the Runoff module and performs dynamic routing of stormwater flows
through the storm drainage system to an outfall. The program will model branched or looped networks,
backwater conditions, free-surface flow, pressure flow or surcharge, flow reversals, flow transfer by
weirs, orifices and pumps, and storage facilities.
Conveyance elements (channels, pipes, etc.) were given a value for the Manning’s roughness coefficient,
which is a measure of the roughness of the element and is used in both XP-SWMM and HEC-RAS to
calculate flows and water surface elevations. These ‘n’ values were selected using field observations,
project photos, aerial photos, and engineering judgment. Additionally, selected channels were idealized
and modeled with trapezoidal or 8-point cross-sections within the Hydraulic module. Where trapezoidal
cross sections were used to represent both channel and overbank a composite ‘n’ value was derived from
a preliminary 100-year storm processed in HEC-RAS.
Overland flow channels were used above all closed conduits to eliminate ponding and facilitate the
movement of surface flow downstream allowing for more conservative peak flows. Each overland flow
channel simulated a cross sectional shape appropriate for its location. This cross sectional shape could
represent a roadway sag over a culvert, a gutter section, a backyard swale, or a side yard swale between
properties.
3.5 MODEL CALIBRATION
The Missouri River and Algoa Study Area encompasses a collection of small watersheds that flow to the
Missouri River, the Moreau River, or the Osage River. None of these streams is gaged, so it is not
possible to calibrate the models to known flows. There are no past studies that examined any of these
areas, and because this study area is a disjoint collection of small watersheds, the USGS Regression
equations are unsuited to evaluate XP-SWMM’s validity. The range of drainage areas for which the
USGS equations are valid is 0.13 to 14,000 square miles for rural areas, and 0.28 to 38.9 square miles for
urban areas in Missouri. The largest subsheds available from this study range from 0.31 to 0.80 square
miles (except for the Algoa area) which places the available watersheds and subsheds at the very bottom
of the valid range. Because “Errors increase appreciably when any of the basin characteristics used in the
equations are near or beyond the range limits,”3 the USGS equations are seen as not reliable for use for
this study.
3USGS Fact Sheet 015-01, The National Flood-Frequency Program—Methods for Estimating Flood Magnitude and
Frequency in Rural and Urban Areas in Missouri, 2000, March 2001
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 12
3.5.1 APWA 5600 Rational Method
A collection of subsheds with less that 200 acres was chosen randomly for this comparison. These
subshed areas were selected and analyzed using the Storm Drainage Design Manual of the City of
Jefferson and the APWA Section 5600’s rational method for calculating peak flows. The Rational
Method 10-year and 100-year peak flows were then compared to the XP-SWMM 10-year and 100-year
peak flows. The results are listed in Table 4-4.
Table 3-3
Small Subshed Flow Comparison
Area
Number Acres
Rational
10-year
flow
(cfs)
SWMM
10-year
flow
(cfs)
10-year
Percent
Difference
Rational
100-year
flow
(cfs)
SWMM
100-year
flow
(cfs)
100-year
Percent
Difference
MZ57052 0.97 2.5 4.2 68% 3.1 7.2 128%
ME00022 2.95 4.2 6.1 48% 5.2 11.6 123%
MZ57510 4.23 12.9 16.1 25% 16.1 27.3 70%
MZ57010 4.46 18.9 28.6 51% 23.6 45.4 92%
MZ57053 5.55 14.0 26.5 89% 17.5 45.0 157%
MZ57559 6.81 13.4 20.4 52% 16.8 36.5 117%
ME58501 7.92 11.5 19.5 69% 14.4 32.0 123%
ME58092 11.58 22.4 15.4 -31% 28.0 27.8 -1%
ME58013 15.29 26.8 30.0 12% 33.5 52.1 55%
MZ57071 15.96 43.7 51.3 18% 54.6 87.1 60%
MZ57549 17.25 31.4 36.7 17% 39.3 66.5 69%
ME00014 17.40 28.8 28.8 0% 36.0 51.9 44%
ME00021 23.62 41.8 31.2 -25% 52.3 57.4 10%
ME58087 29.26 117.4 65.2 -44% 146.7 103.0 -30%
MZ00003 31.94 75.6 81.1 7% 94.5 142.4 51%
ME00033 33.95 55.8 25.4 -55% 69.8 47.1 -33%
ME58023 39.25 63.3 61.9 -2% 79.2 110.4 39%
ME00189 49.45 80.4 74.0 -8% 100.4 130.0 29%
Average difference 16% Average difference 25%
There are large individual variations, but the average differences are +16% for the 10-year flows and
+25% for the 100-year flows. Because the Rational Method is a much simpler method for calculating
flow, these types of variations are expected. However, these comparisons are useful in monitoring the
SWMM models. In the course of this evaluation, a large number of checks were made between the
collected variables and the actual numbers in the study models, such as soil type, slope, land use, conduit
statistics, etc., and these helped to verify the accuracy of the model building procedure.
When the results are ordered by size it can be seen that the Rational Method tends to understate runoff
from smaller areas and overstate runoff from larger areas. This lends credibility to the SWMM models
developed for this study because this is an expected result from the Rational Method.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 13
The subsheds analyzed for this study were aggregated into bins of roughly similar size to eliminate the
expected scatter. When a logarithmic regression curve is plotted with these points, there is a very good fit
with a high correlation coefficient.
3.5.2 Conclusion
Although it is never desirable to proceed without gage data for calibration, it was done here, as it is
commonly done elsewhere due to the scarcity of gaged streams. Lacking this validation, the process of
checking different methods against one another is useful because it allows the model builder to
demonstrate that the model results are consistent with generally accepted practices in calculating these
statistics.
The Rational Method comparisons showed pretty good accuracy and expected trending when large and
small areas were compared.
There were more checks performed for the other models constructed for previous phases of this study,
and in each instance the model results were found to be valid. Because this study examines neighboring
areas with similar geographic and hydrologic characteristics, and uses similar methodology, the same
software, and the same modeler, the integrity of the results of this study are seen to be valid with only
Rational flows for comparison.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 14
SECTION 4.0 - HYDRAULIC MODELLING
4.1 INTRODUCTION
The HEC-RAS program (Version 3.1.2) was used to calculate water surface profiles for steady, gradually
varied flow in natural and improved open channels. The model was also used to evaluate the effects of
various obstructions such as bridges, culverts, weirs and structures within the floodplain of the modeled
stream. HEC-RAS estimates water surface elevations in a river reach based on flows from the hydrologic
block (RUNOFF) of XP-SWMM. This section discusses the procedures used for this project and
guidelines developed during previous studies for developing HEC-RAS models. This section describes in
detail data development, model development, model-input parameters, data format, naming conventions,
and calibration.
Table 5-1 summarizes some of the watershed characteristics incorporated into the HEC-RAS model.
Table 4-1
Summary of Missouri River Study Area
HEC-RAS Model
Number of Reaches Modeled 7
Total Miles of Stream Network Modeled 6.45
Total Number of Cross-Sections 175
Average Cross-Section Spacing (ft) 195
Total Number of Hydraulic Structures Modeled 14
Number of Culverts Modeled 11
A summary of input parameters is presented in Table 5-2 and developed as follows:
Table 4-2
Data Development
Model Parameter
Data Development
Method Requirements
Stream Network ArcView/GIS and HEC
GeoRAS
Stream network shapefile with stream reach
identifiers
Cross-Sections ArcView/GIS and HEC
GeoRAS TIN, cross-section cut-line shapefiles
Flow Lengths ArcView/GIS and HEC
GeoRAS
Channel and overbank (left and right) flow
path shapefiles
Channel Manning’s “n”
Values
ArcView/GIS and
Manual Input
Assigned by engineer and adjusted during
calibration, aerial photos
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 15
Table 4-2
Data Development
Model Parameter
Data Development
Method Requirements
Overbank Manning’s
“n” Values
ArcView/GIS and
Manual Input
Land surface shapefiles created from aerial
photos
Roadway Crossings
Field Survey,
ArcView/GIS and
Manual Input
Roadway profile and bridge or culvert opening
Expansion and
Contraction Coefficient Manual Input Photos, contour and cross-section shapefiles
Boundary Conditions Manual Method and
HEC-RAS Normal depth calculations
Ineffective Flow Areas Manual Input Photos, contour and cross-section shapefiles
Channel Bank Stations ArcView/GIS and
Manual Input Cross-section shapefiles
Exhibit 6 shows the basic structure of the hydraulic model as well as the newly established floodplains.
4.2 DIGITAL TERRAIN MODEL
A digital terrain model (DTM) was developed from the mapping data provided by the City. The DTM’s
purpose for this study was to allow computer software to extract channel centerlines and cross section
data. Using HEC-GeoRAS, the information contained in the mapping was extracted from the DTM and
imported into the HEC-RAS model.
4.3 STREAM NETWORK
The stream network was derived from the hydrography information contained in the City data. In effect,
the stream network represents the channel centerlines of the streams modeled in HEC-RAS.
4.4 CROSS-SECTION CUT-LINES
Placement and alignment of cross sections are determined by engineering judgment. The maximum
spacing between cross sections is 500 feet. Additional cross sections are added at bridges and culverts.
As prescribed in the HEC-RAS Hydraulic Reference Manual4, four cross sections are associated with each
hydraulic structure as follows:
4 HEC-RAS River Analysis System Hydraulic Reference Manual, United States Army Corps of Engineers
Hydrologic Engineering Center, Version 3.1, November 2002
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 16
• Cross Section 1 is placed approximately 4 times the opening width downstream of the
structure.
• Cross Section 2 is placed at the downstream face of the structure, just outside of the roadway
embankment.
• Cross Section 3 is placed at the upstream face of the structure, just outside of the roadway
embankment.
• Cross Section 4 is placed approximately 1 times the width of the opening upstream of
structure.
Cross sections were delineated from left to right looking in the downstream direction and were drawn so
that each end projected beyond the maximum extent of the 500-year floodplain. Cross section stations
reflect the distance in feet from confluence.
4.5 MANNING’S “n” VALUES
Manning’s “n” values are empirical coefficients used to relate surface conditions to conveyance friction
losses in the HEC-RAS model. Table 5-3 below shows the relationship between land cover and
Manning’s “n” values. Typically, roughness coefficients used for this study were taken from the HEC-
RAS Reference Manual.
Table 4-3
Manning’s Roughness Coefficients
Land Cover Manning's “n” Value
Urban residential (high/low density) 0.060
Urban commercial 0.050
Pavement 0.013
Floodplain; no brush 0.035
Floodplain; brush and trees 0.090
Dense trees 0.11 to 0.15
Light brush and trees 0.060
Grass, no brush 0.035
Crops 0.035
4.6 BRIDGES AND CULVERTS
For this study, 14 culverts were modeled in accordance with the recommended procedures outlined in the
HEC-RAS Hydraulic Reference Manual and summarized below.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 17
4.6.1 Cross Sections
Cross-sections 1 and 4 were located sufficiently upstream and downstream from the structure to represent
undisturbed flow in the channel. Cross-section 2 was located just downstream of the bridge face outside
of the roadway embankment. And finally, Cross-section 3 was located just upstream of the bridge face
beyond the limits of the roadway embankment.
4.6.2 Bridge Deck / Roadway
Bridge Deck/Roadway information was acquired from the topographic survey. Where survey data proved
to be insufficient, the data was supplemented with information from the base mapping.
4.6.3 Modeling Approach
Typically, the highest energy answer between Energy (Standard Step) and Momentum method was
selected for low flow calculations. For high flow calculations, the Pressure and/or Weir method was
used. As an exception, perched bridges and culverts were modeled using Energy methods. It should be
noted that this approach to bridge modeling was a general philosophy, but not a hard and fast rule. The
results from each bridge were evaluated, and engineering judgment was used to obtain reasonable results.
4.6.4 Internal Bridge Cross Sections
As general rule, internal bridge cross sections were not modified. However, some revisions to internal
cross sections may have been necessary. Specifically, when Cross Sections 2 and 3 were not cut
perpendicular to the bridge face, the deck / roadway would be obscured by the cross-sections. With weir
area (roadway) obscured, HEC-RAS uses the cross section points as the weir. As a result, the calculated
head on the weir is often overestimated. Where this conservatism was of particular concern, the internal
bridge cross section was modified so that the all of the roadway points were used for weir flow.
4.7 INEFFECTIVE FLOW AREAS
Ineffective flow areas were determined using cross-section plots, contour information and photos.
Ineffective flow area examples include:
• Floodplain areas significantly below the top of the channel bank not hydraulically
connected to the channel downstream
• Floodplain areas within hydraulic shadow of roadway encroachments caused by
contraction and expansion of flow through bridge or culvert openings
• Floodplain areas within hydraulic shadow of other obstructions or irregularities in the
stream valley floodplain
4.8 EXPANSION AND CONTRACTION COEFFICIENTS
Expansion and contraction coefficients were estimated based on the ratio of effective flow area in the
floodplain occurring at stream valley cross-sections, roadway crossings, and dams. Table 5-4 lists typical
coefficients used in the model. For roadway crossings, expansion and contraction coefficients were
applied to the first two cross-sections upstream and one cross-section downstream of the structure.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 18
Table 4-4
Expansion and Contraction Coefficients
Transition Type Expansion
Coefficient
Contraction
Coefficient
Gradual 0.3 0.1
Roadway Crossing 0.5 0.3
Abrupt 0.8 0.6
Data from HEC-RAS Hydraulic Manual
4.9 FLOW DATA
For this study, one-dimensional, steady state flows is used as a basis for hydraulic modeling. The peak
flow rates at points of interest in the watershed are estimated using the Runoff module described in
Section 4 of the report.
4.9.1 Profiles
Peak flow rates from the 2, 5, 10, 25, 50, and 100-year storms were used in the hydraulic analysis.
4.9.2 Flow Change Locations
At a minimum, HEC-RAS requires a flow rate to be established at the top of each reach. Theoretically,
flow rates increase continuously along a reach because of lateral inflow of runoff. While it would be
impossible to account for continuous increases in flow rate, it is appropriate to increase the flows at
particular cross section locations. These locations in the hydraulic model are reflective of hydrograph
calculations in the hydrologic model.
4.9.3 Boundary Conditions
Because all of the streams modeled are controlled by the stream or river they discharge to, boundary
conditions are set to normal flow conditions.
4.9.4 Flow Conditions
Floodplain information was calculated for two types of land uses: existing conditions and future surface
conditions as discussed in Section 3.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 19
4.9.5 Detention / Storage
Because HEC-RAS is a steady state model it cannot inherently model attenuation created by ponds, lakes,
and some highway embankments. Attenuated flow locations were modeled in XP-SWMM, and the
results were incorporated into HEC-RAS.
4.10 FLOODWAY ANALYSIS
Floodway limits were not determined as part of this study.
4.11 CALIBRATION
Due to the lack of any physical data (such as gage records) indicating high water elevations for a known
flow recurrence interval, true calibration (as defined in the scientific community) could not be performed.
Therefore, a comparative analysis was completed using several available sources of information.
4.11.1 Previous Studies
Several previous hydrologic and hydraulic studies have been performed in and around the City of
Jefferson including the FEMA FIS for Cole County and the City of Jefferson. These studies were
reviewed and pertinent information used.
4.11.2 Stormwater Questionnaire
A stormwater questionnaire distributed in July of 2001 for Phase I of this study proved to be helpful as
well. Using GIS, the results of the questionnaires could be plotted on the mapping with the floodplain.
Results of the model generally corroborated the problem areas revealed by the questionnaire. Clusters of
reported flooding indicated major areas of concern caused by obstructions or undersized channels.
Scattered areas of reported flooding were more indicative of localized problems such as downspouts and
clogged drainage systems. A thorough discussion and analysis of this survey is available in the Phase I/II
study5.
4.12 QUALITY CONTROL / DEBUGGING
Once the HEC-RAS models were calibrated, a final examination of the input parameters was made using
the Check-RAS program distributed by FEMA (Version 1.1).
According to the documentation accompanying the program: Check-RAS is a program designed to check
the reasonableness of the data found in HEC-RAS. Geometric, steady flow, and output data are three
types of data used to verify that hydraulic estimates and assumptions made in the model appear to be
justified and are in accordance with the assumptions and limitations of the HEC-RAS program and
applicable FEMA requirements.
Check-RAS allows users to examine a variety of parameters from HEC-RAS data files, as well as
generate, view, and print reports, which include tables and messages. Using the HELP message database
can reference additional information about the messages identified.
5Burns & McDonnell, Comprehensive Stormwater Master Plan Update Phases 1 & 2, October 2003
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 20
Although the HEC-RAS program provides several messages, CHECK-RAS differs from HEC-RAS in
several ways. Only, CHECK-RAS does the following:
• Categorizes floodplain modeling into five distinct areas of checks
• Provides a summary table and messages for each area of check
• Assesses the suitability of roughness coefficients and transition loss coefficients
• Assesses the suitability of starting water-surface elevations
• Assesses bridge and culvert modeling
• Provides a detailed floodway analysis
• Compares important parameters among multiple profiles
• Proposes solutions through the use of the Help screens
Each Check-RAS warning was reviewed and evaluated for applicability. Necessary changes were made
to the HEC-RAS model.
4.13 Digital Models
Table 4-5
HEC-RAS Models
Plan Geometry Flow Description
Existing Conditions Missouri River
Area – Existing
Conditions
Existing
Conditions
Flow
P4.p01 P4.g01 P4.f01
Model represents
flows for existing
land use conditions
and the existing
conveyance system.
Future Surface
Conditions
Missouri River
Area – Existing
Conditions
Future Surface
Conditions
Flow
P4.p02 P4.g01 P4.f02
Model represents
flows for future
land use conditions
and the existing
conveyance system.
Table 4-6
XP-SWMM Models
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 21
Name Study Area Description
MoRiv&AlgoaEX.xp
Missouri River
and Algoa
District
Existing Conditons model for 2, 5, 10,
25, 50, and 100-year storms.
MoRiv&AlgoaFU.xp
Missouri River
and Algoa
District
Future Conditons model for 2, 5, 10,
25, 50, and 100-year storms.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 22
SECTION 5.0 - EXISTING SYSTEM PERFORMANCE
5.1 Missouri River and Algoa Study Area
The Missouri River and Algoa Study Area (see Exhibit 1) is made up of areas of the Missouri River
watershed within the city limits, including an area identified as the Algoa Area (see Exhibit 1). Different
parts of the Study Area drain to the Missouri River, Moreau River, Rising Creek, and Osage River.
5.1.1 Land Use
Portions of the study area are city neighborhoods that are fully developed in residential or commercial
use. These areas are along the Missouri River on either side of the Capitol Building. Although there is
redevelopment occurring at the site of the old prison, the hydrologic characteristics do not change, and no
changes are expected between current and future land use in these areas.
Other parts are near-rural and subject to future industrial development, primarily in the Algoa Area. The
Algoa Area is already home to several large industrial and several large public facilities, but these account
for only about 35% of this area (about 1,250 acres)—there remains 2,300 acres available for development.
Because of this, future land use for this area shows a large increase in the industrial classification with an
accompanying increase in stormwater runoff.
The land use classifications used to calculate the hydrologic parameters that drive this study are shown
below in Table 5-1, and in Exhibits 4 and 5.
Table 5-1
Land Use Breakdown for Missouri River & Algoa Study Area
Land Use Designation
Total Area
(acres)
Percent of
Watershed
Existing Surface Conditions (observed from aerial photography)
Agricultural 2023.732.80%
Brush 862.314.00%
Commercial 277.64.50%
High Density Residential 19.40.30%
Impervious 61.61.00%
Industrial 543.18.80%
Low Density Residential 97.91.60%
Medium Density Residential 629.610.20%
Meadow & Pasture 415.26.70%
Right of Way 329.55.30%
Wooded 906.314.70%
Table 5-1
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 23
Land Use Designation
Total Area
(acres)
Percent of
Watershed
Future Surface Conditions
Commercial 575.210.30%
Floodplain 1112.819.90%
High Density Residential 19.40.30%
Impervious 32.60.60%
Industrial 2181.239.10%
Low Density Residential 731.30%
Medium Density Residential 753.313.50%
Meadow & Pasture 29.60.50%
Right of Way 278.75.00%
Steep 106.11.90%
Wooded 423.67.60%
5.1.2 Hydrologic Summary
A summary is on the next page of the major hydrologic characteristics of the watershed. The differences
between existing and future flows highlights the places in the watershed where the most development is
expected, and the unit flows are a useful measure for assessing the validity of the model. The table shows
the model outflows from the larger outfalls in the study area (shown in Exhibit 7).
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 24
Table 5-2
Hydrologic Characteristics of Missouri River and Algoa Study Area
Total Drainage Area (ac) 7735.4
Total Drainage Area (sq mi) 12.09
Number of Subsheds Modeled 218
Average Subshed Size (ac) 35.5
SCS Composite Curve Number Existing 76.52 Future 81.68
10-year Event 100-year Event
Outfall
* Area (ac) Existing Future
Increas
e
Existin
g Future
Increas
e
Peak Flow Rate (cfs) 360.15 363.43 639.92 647.29 1 200.72 Unit Discharge (cfs/ac) 1.79 1.81 0.9% 3.19 3.22 1.2%
Peak Flow Rate (cfs) 233.12 235.57 376.03 381.79 2 88.24 Unit Discharge (cfs/ac) 2.64 2.67 1.1% 4.26 4.33 1.5%
Peak Flow Rate (cfs) 380.126379.596678.68 678.541 3 140.09 Unit Discharge (cfs/ac) 2.71 2.71 -0.1% 4.84 4.84 0.0%
Peak Flow Rate (cfs) 185.19 195.17 339.83 356.91 4 206.81 Unit Discharge (cfs/ac) 0.90 0.94 5.4% 1.64 1.73 5.0%
Peak Flow Rate (cfs) 332.24 548.92 472.42 754.04 5 286.72
Unit Discharge (cfs/ac) 1.16 1.91
65.2%
1.65 2.63
59.6%
Peak Flow Rate (cfs) 1465.26 2226.04 2433.64 3270.33 6 5119.00
Unit Discharge (cfs/ac) 0.29 0.43
51.9%
0.48 0.64
34.4%
Peak Flow Rate (cfs) 349.92 651.35 580.87 994.06 7 515.33
Unit Discharge (cfs/ac) 0.68 1.26
86.1%
1.13 1.93
71.1%
*See Exhibit 7
5.1.3 Existing Drainage System
Within this Study Area there are 12 hydraulic structures modeled in HEC-RAS and 181 'links' (culverts or
pipe runs) modeled in XP-SWMM. These links comprise about 4.7 miles of stormwater conduits 24
inches and larger. The link names do not correspond exactly with the surveyed conduit names because of
modeling constraints. Therefore the GIS and XP-SWMM files furnished to the City and County must
sometimes be used to find the locations and statistics associated with each.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 25
5.2 EVALUATION CRITERIA
The design criteria for system performance currently observed by the City of Jefferson is based on land
use or zoning. These criteria have been taken from the Storm Drainage Design Manual6 and are as
follows:
Table 5-3 – Existing Design Criteria for Enclosed Systems and Culverts
Land Use / Zoning Designation
Return Frequency the System Must
Accommodate
Residential 10 yr
Commercial 25 yr
Industrial 25 yr
Government and Institutional 25 yr
Floodway in 100-yr Floodplain 100 yr
Table 5-4 – Existing Design Criteria for Open Channels
Land Use / Zoning Designation
Return Frequency the System Must
Accommodate
Residential 25 yr
Commercial 25 yr
Industrial 25 yr
Government and Institutional 25 yr
All Others 10 yr
Floodway in 100-yr Floodplain 100 yr
For various reasons these design criteria cannot be the sole criteria for evaluating the system. Much of
this study examines older elements of the stormwater conveyance system as well as portions of it that are
outside the City limits and were not subject to City regulation when built. In addition, these are design
criteria, meant to be applied to new construction. Hence evaluating the performance of the system is
more complicated than simply flagging elements that do not pass the runoff from the applicable event.
5.3 DRAINAGE SYSTEM PERFORMANCE
The drainage system was evaluated as two separate parts: enclosed system and open channels. An
enclosed system was defined as multiple, connected pipes. As such, all of the elements considered as
enclosed systems were in the upper reaches of the watersheds and were modeled in XP-SWMM. These
enclosed systems then discharged into open channels and were modeled in HEC-RAS. This combination
of modeling techniques was used because XP-SWMM models enclosed systems better than HEC-RAS,
and HEC-RAS better represents extended open channel systems.
6 Storm Drainage Design Manual, Public Works Department, City of Jefferson, Missouri, 1985.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 26
5.3.1 Major Structure Modeling Results from HEC-RAS
Table 5-5 summarizes the major structures analyzed in the Missouri River Study Area with HEC-RAS.
The table provides a brief description of the structure, its length and a listing of the hydrologic conditions
examined. “Existing” indicates the flow at each structure with the current ground cover and land uses
observed in the watershed. “Future” is the future flow predicted to occur as the watershed develops. The
table also provides an indication of whether modeling predicts overtopping of the structure for three key
runoff events. These structures can be located in Exhibit 6 and the results can be examined more closely
in the HEC-RAS model digital files furnished with this report.
The City's design criteria require that structures in residential streets convey a 10-year event without
overtopping. Bridges and culverts on commercial streets must convey a 25-year event without
overtopping.
Table 5-5
HEC-RAS Analysis of Major Structures
10-yr Event 25-yr Event 100-yr Event
Struct
. No.
City or
County
Descriptio
n
(dimension
in feet)
Lengt
h (ft)
Hydrologi
c
Condition
Flow
(cfs)
Overto
p (ft)
Flow
(cfs)
Overto
p (ft)
Flow
(cfs)
Overto
p (ft)
Existing 151 0 171 0 215 0.29 ME-
002
City,
commercial 6.0 CMP 22 Future 335 0.53 395 0.62 499 0.75
Existing 165 0.38 193 0.67 239 1.01 ME-
003
City,
commercial 6.0 CMP 140 Future 358 1.56 424 1.77 531 2.05
Existing 1407 0 1807 0 2539 0 ME-
005
City,
commercial
2 - 12.0 x
18.0 RCB 720 Future 1515 0 1923 0 2706 0
Existing 1407 0 1803 0 2524 0 ME-
006
City,
commercial
2 - 15.0 x
12.0 RCB 464 Future 1512 0 1918 0 2691 0
Existing 457 0 561 0 769 0 ME-
007
City,
commercial
8.0 x 7.0
RCB 168 Future 666 0 776 0 941 0
Existing 1457 0 1858 0 2548 0 ME-
008
City,
commercial Bridge 12
wide Future 1557 0 1966 0 2683 0
Existing 220 0 453 0 584 0 ME-
009
City,
commercial
8.0 x 8.0
RCB 117 Future 510 0 591 0 692 0
Existing 1481 0 1864 0 2532 0 ME-
010
City,
commercial Bridge 23'
wide Future 1766 0 2029 0 2664 0
Existing 1508 0 1888 0 2556 0 ME-
011
City,
commercial
2 - 15.0 x
12.0 RCB 109 Future 1810 0 2131 0 2697 0
Existing 1551 0 1910 0 2578 0 ME-
012
City,
commercial Bridge 28'
wide Future 2247 0 2643 0 3305 0
Existing 187 0 237 0 342 0 ME-
013
City,
commercial
7.0 x 7.0
RCB 107 Future 193 0 244 0 352 0
Existing 364 0 460 0 647 0 ME-
014
City,
commercial
10.0 x 23.0
Stone Arch 50 Future 364 0 460 0 647 0
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 27
The analysis suggests that the following structures lack sufficient capacity to current design standards:
• ME-002 goes under a dirt road that provides access below the Algoa landfill west of
Shamrock Road
• MR-003 is under a dirt road that provides access to the fields west of Shamrock Road and
south of Algoa Road.
5.3.2 Minor Structure Modeling Results - Surcharging
The performance of the pipes that make up the minor systems is reported in Appendix B and in the GIS
and XP-SWMM files furnished digitally with this report. In Appendix B the occurrence and depth of
overtopping and the time of surcharging in minutes is reported. The locations of these pipes are shown in
Exhibit 8 and the GIS files.
5.3.2.1 Overtopping
The depth of overtopping was determined by modeling an aboveground channel above each pipe so that
runoff was allowed to travel downstream when pipe capacities were exceeded. Four types of overland
channels were modeled: street and gutter flow; flow over a sag in the road above a culvert; flow between
houses through a side yard swale; and the flow through backyard swales. The overtopping elevation, the
slope, and the sides of each of these trapezoidal channels is estimated for each different type and location.
Due to the accuracy and resolution of elevations and topographic data these overland channels and depths
only approximate actual conditions, but are still useful measures of performance. The model suggests
that six percent of the links fail to pass the existing 10-year flow without overtopping, and in the future
conditions scenario ten percent will overtop.
5.3.2.2 Surcharging
Surcharging is an important parameter to examine when evaluating the capacity of stormwater systems,
but it is not a completely straightforward process to obtain or to report. Broadly speaking, surcharging
occurs when a pipe begins to run full, so the overland flow reported in Appendix B indicates surcharging.
However it is also useful to report the amount of time that a pipe is in the surcharged condition. If a pipe
is surcharged for an hour, then it presents a quite different warning flag than one that is only surcharged
for a few minutes.
In order to measure this in XP-SWMM the overland links are removed and the duration of surcharging is
directly reported. The weakness of this model is that without the overland path, the water can remain at a
node when it could be traveling downstream, so the succeeding channels and pipes do not receive the
same peak flows as they do in the more complete model.
The statistics reported from this model are length of surcharged time for ten-year and twenty-five-year
events for existing and future conditions.
Both overland depth and duration of surcharging are reported in Appendix B and in the GIS database
files associated with those links. Additional information is available directly from the XP-SWMM model,
such as animated graphics and more technical measures. Exhibit 8 shows the surcharged pipes.
However, the elements shown as surcharged are only those that meet the following criteria: if residential,
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 28
they have more that 0.5 feet of depth at either end of the overland channel or are surcharged for more that
30 minutes in the 10-year event. If commercial or industrial, then they must have more than 0.5 feet of
depth at either end or surcharge for more than 30 minutes in the 25-year event. These threshold
parameters are somewhat arbitrary and are only for the purposes of graphic representation in the exhibit.
It should be noted that there are elements that report a depth of flow in the overland channel (from the
first model), but do not show a surcharged time (from the second model). This apparent inconsistency
occurs because not all of the water is transmitted downstream at the same time in both models, so peak
flows, depths, and times are not expected to match perfectly.
The recommendations made in Section 6 factor in field investigations by the Engineer, complaints, staff
feedback, special conditions, and the age and condition of the system; hence these surcharge statistics
simply offer a fuller picture of the performance of the minor system.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 29
SECTION 6.0 - RECOMMENDATIONS
6.1 INTRODUCTION
The recommendations made in this section are generated from a combination of model results,
observations (Engineer, City, County, and Surveyor), and reports from City officials and citizen
questionnaires.
Most of these recommendations are structural and are intended to fix problems that already have some
urgency with respect to structure flooding, erosion, or street flooding. Some of these have arisen because
of the aging infrastructure and associated problems. There are other issues that exist because of the
increasing urbanization in the watersheds, both from increased runoff and floodplain encroachment.
Also noted in this section are sites that are currently at or beyond their capacity, but for which no
recommendation is made for improvement. These sites are either recently constructed or are on private or
State property. They do not appear to be safety hazards nor do they place occupied buildings at risk.
6.2 SURVEYOR'S OBSERVATIONS
The need for maintenance of each surveyed structure was noted by the Surveyor. A numerical rating of 1
(no maintenance), 2 (routine maintenance), or 3 (critical maintenance) was given to each structure.
Comments were appended to about half of the structures (although many comments concerned
connections or structural details) in the GIS database, and one or more digital photographs are available
for examination for each structure.
It should be noted that because the Surveyors examined only portions of the system visible from
aboveground, and because their ratings may not agree with the ratings of an experienced maintenance
person, then the Surveyors' judgment of "no maintenance" may not be meaningful in all cases.
The structures that received a numerical rating of 2 or 3 are shown below in Table 6-1:
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 30
Table 6-1
Surveyors Maintenance Comments
Node ID Type of
Maintenance Surveyor's Comments
MZ57007 3 Pipe is over 1/2 filled with concrete.
MZ57045 3 Channel & pipe are extremely clogged
MZ57046 3 Pipe is half full of debris
MZ57541 3 Manhole cover is broken
MZ57563 3 Pipe has been silted over
ME58065 3 P-3 is smashed & full of mud, area around is a sink hole
ME58513 3 Silted in
MZ57011 2 Bottom is showing rust
MZ57012 2 Bottom is showing rust
MZ57015 2 (none)
MZ57016 2 Pipe out of ground
MZ57017 2 Looks like where pipe pi's
MZ57075 2 (none)
MZ57570 2 Needs to be cleaned
MZ57582 2 (none)
ME58005 2 Ditch need to be cleaned out to uncover pipe
ME58015 2 Structure need to be cleaned out
ME58040 2 Ditch needs to be cleaned out
MZ57530 2 Pipe is underwater
MZ57576 2 Needs to be opened up
ME58066 2 Area around box is collapsing in
MZ57l061 2 Pipe is blocked
6.3 EVALUATION OF PRIORITIES
6.3.1 Methodology
The improvements suggested as part of this study will be discussed and ranked based on the estimated
level of service, potential flooding, frequency of flooding, and engineering judgment. Rather than a
numerical ranking suggesting an order for which improvements should be made, a ranking of high,
medium, low, or future priority will be used to prioritize the projects. This will provide the City the
flexibility to evaluate and fund projects as the need arises.
6.3.2 Priority Definitions
6.3.2.1 HIGH Priority
A HIGH priority is assigned to those areas meeting one of the following:
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 31
• Habitable buildings are located in the floodplain and flooding is frequent.
• Flooding could pose an immediate threat to public safety.
• Opportunities for proactive, non-structural measures will be lost if not initiated
expeditiously.
6.3.2.2 MEDIUM Priority
A MEDIUM priority is assigned to those areas meeting all of the following criteria:
• There is a flooding problem that does not involve a habitable building located in
the floodplain.
• There is a flooding problem that does not pose an immediate threat to public
safety.
• The required level of service for a bridge or culvert on a major roadway is
expected to be exceeded.
6.3.2.3 LOW Priority
A LOW priority is assigned to those areas meeting either of the following criteria:
• The required level of service for a bridge or culvert on a minor roadway is
expected to be exceeded.
• A stormwater issue exists due to erosion or yard flooding.
6.3.2.4 FUTURE Priority
A FUTURE priority is assigned to the areas meeting one or all of the following:
• Modeling indicates no flooding problem for existing conditions.
• Modeling indicates a possible problem (generally a decrease in the level of
service) as the upstream tributary area becomes urbanized.
• A low water crossing exists in an area subject to increasing urbanization and its
eventual replacement should be considered.
6.3.2.5 REVIEW During Future Development
There are parts of the system that exhibit surcharging (pipe-full or bank-full flow) or minimal overland
flow, but are not a hazard. However, these areas may be sensitive to upstream development or
degradation of the system, and are included in the Recommendations section of the report and are meant
to serve as warning flags for future planners.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 32
A REVIEW DURING FUTURE DEVELOPMENT priority is assigned to the areas meeting all of the
following:
• The system is surcharging in this location.
• There is no hazard to occupied dwellings.
• There is little or no degradation in the level of service of roadways.
6.4 Cost Opinions for Projects
In the following recommendations a cost opinion is included with most projects. An attempt was made to
present realistic costs in 2005 dollars. The costs of concrete and steel have both risen considerably in the
last year, and it is impossible to predict what they will happen to these prices in the future.
The costs of RCP and structural concrete were estimated generously, and to arrive at these numbers, it
was assumed that demolition of existing structures would be required, that additional excavation and
hauling, bedding, backfill, compaction, finish grading, seeding, and purchase and transportation of the
pipe or RCB. Judgments were made for traffic control and utility relocation, and a healthy contingency
amount was added to each estimate.
The estimated cost to Remove and Replace portions of the roadway so that culverts can be installed
includes pavement removal and disposal; new base material, grading and compaction; curbs and gutters;
and 6” of asphalt concrete.
The estimates and projections prepared by Burns & McDonnell relating costs are based on our
experience, qualifications and judgment as a professional consultant. Because Burns &McDonnell has no
control over weather, cost and availability of labor, material and equipment, labor productivity,
construction contractor's procedures and methods, unavoidable delays, construction contractor's methods
of determining prices, economic conditions, government regulations and laws (including the
interpretation thereof), competitive bidding or market conditions and other factors affecting such
estimates or projections, Burns & McDonnell does not guarantee that actual rates, costs, performance,
schedules, etc., will not vary from the estimates and projections prepared by Burns & McDonnell.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 33
6.5 PROJECT 1 – Main St. & Circle Dr. (City Project)
6.5.1 Description
There is severe damage from flooding reported at the second house on Circle Drive (see Figure 6-1).
There are two houses located in a local sump, and about 15 acres drains through this small system. A 24-
inch pipe transitions to a 20-inch pipe which feeds larger downstream pipes. At this transition (to the
smaller pipe), there is a grated drop inlet in the complainant's back yard, and this makes these residences
susceptible to flooding from the grate inlet whenever the pipes surcharge. In the 25- event, this
surcharging lasts for about an hour.
There is no hydraulic problem with the downstream infrastructure. The 20-inch pipe opens up to a 3-foot
x 2.7-foot, then a 4-foot x 3-foot box culvert, and then a 360-foot long run of 3.5-foot corrugated metal
pipe that discharges into an open channel. However, it is reported that the inlet on the east side of Circle
Drive is caving in.
The basic problem is that there is an opening for water to leave the system in a sump and the next pipe
downstream from this grate inlet is undersized.
6.5.2 Recommended Improvement
The backyard inlet (MZ57545), and inlets on both sides of Circle Drive (MZ57075 and MZ57074) should
be replaced. The 20-inch pipe (MZ65) should be upsized to a 24-inch pipe, and the pipes connecting the
street inlets (MZ64) and the junction box (MZ63) can also be replaced with 24-inch pipes.
The pipes and inlets along Main Street appear to be properly sized and should not have to be replaced.
However there is a buried junction (MZ57073) leading to a steep slope into the backyards that will have
to be examined in the design phase of this project.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 34
6.5.3 Cost Opinion
Description Quan. Unit
Unit
Price Total Cost
Main St. & Circle Dr.
Remove Existing Pipe 190 LF $10.50 $1,995
Excavation 426 CY $4.92 $2,096
Bedding 64 CY $40.00 $2,560
Material to be hauled off site 39.2 CY $9.70 $380
Backfill and compaction 341 CY $28.15 $9,599
RCP 24" 190 LF $25.00 $4,750
Inlet Structures 4 EA $5,090.00 $20,360
R&R Pavement 69.2 SY $43.00 $2,976
Finish Grading 570 SY $4.00 $2,280
Hydromulching 5100 SF $0.44 $2,244
Subtotal $49,240
Erosion Control 2 % $985
Mobilization / Demobilization 5 % $2,462
Traffic Control 2 % $985
Utility Relocation 2 % $985
Subtotal $54,656
Contingency 25 % $12,310
Construction Total $66,966
Engineering, Surveying, Geotechnical,
Permitting & Construction Management 50 % $33,483
PROJECT TOTAL
$100,44
9
6.5.4 Priority
A HIGH priority is assigned to this project because of the history of home flooding.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 35
6.6 PROJECT 2 – High Street & Benton Street (City Project)
6.6.1 Description
There are reports of house flooding, yard flooding, street flooding, and erosion problems in this
neighborhood (see Figure 6.2). The modeling suggests that there is surcharging and overland flow due to
undersized pipes throughout the system.
6.6.2 Recommended Improvement
To correct the problem the modeling suggests that the upper part of this small system (the pipes labeled
MZ33, MZ34, and MZ20) could be replaced with 30-inch pipes to adequately increase capacity. In the
lower part the pipes labeled MZ35 and MZ36 are currently 24-inch and 36-inch diameter pipes, and could
be replaced with 42-inch pipes.
It should be noted that the smaller, collector pipes that also comprise the system but were not analyzed in
detail will need to be examined for inclusion in this project.
6.6.3 Cost Opinion
Description Quan. Unit Unit Price Total Cost
High St. & Benton Dr.
Remove Existing Pipe 843 LF $12.98 $10,942
Excavation 2546 CY $4.92 $12,526
Bedding 527 CY $40.00 $21,080
Material to be hauled off site 273 CY $9.70 $2,651
Backfill and compaction 1828 CY $28.15 $51,458
30" RCP 679 LF $40.20 $27,296
42" RCP 164 LF $58.90 $9,660
Inlet Structures 5 ea $5,090 $25,450
R&R pavement 366 SY $43.00 $15,738
Finish Grading 2680 SY $4.00 $10,720
Hydromulching 24150 SF $0.44 $10,626
Subtotal $198,147
Erosion Control 2 % $3,963
Mobilization / Demobilization 5 % $9,907
Traffic Control 3 % $5,944
Utility Relocation 5 % $9,907
Subtotal $227,869
Contingency 25 % $56,967
Construction Total $284,836
Engineering, Surveying, Geotechnical,
Permitting & Construction Management
20 % $56,967
PROJECT TOTAL $341,804
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 36
6.6.4 Priority
A HIGH priority is assigned to this project because of complaints and the potential for structure flooding
in several places.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 37
6.7 PROJECT 3 – Allen Drive (City Project)
6.7.1 Description
The modeling suggests that there is substantial overland flow in both the existing and future 10-year
storm events (see Figure 6-3). Damage to property is problem for at least one homeowner, but depths of
water in Allen Court and Cole Drive could be hazardous. According to the stormwater survey, yard
flooding and street flooding occur frequently in this area.
6.7.2 Recommended Improvement
According to the model, all of the surcharging and overland flow can be eliminated if two downstream
pipes (MZ67 and MZ69, currently 30-inch and 36-inch pipes) are replaced with 42-inch pipes. There is
nothing reported by the Surveyor with respect to condition, so if the rest of the pipes and inlets are in
satisfactory condition, then this partial replacement of the system should solve the problem.
6.7.3 Cost Opinion
Description Quan. Unit Unit Price Total Cost
Allen Dr.
Remove Existing Pipe 357 LF $13.27 $4,737
Excavation 1428 CY $4.92 $7,026
Bedding 370 CY $40.00 $14,800
Material to be hauled off site 81 CY $9.70 $786
Backfill and compaction 926 CY $28.15 $26,067
42" RCP 357 LF $59.00 $21,063
Inlet structure 1 EA $5,090.00 $5,090
Outlet structure 300 SF $10.00 $3,000
Finish Grading 1520 SY $4.00 $6,080
Hydromulching 13700 SF $0.44 $6,028
Subtotal $82,569
Erosion Control 2 % $1,651
Mobilization / Demobilization 3 % $2,477
Traffic Control 1 % $826
Utility Relocation 5 % $4,128
Subtotal $91,651
Contingency 25 % $22,913
Construction Total $114,564
Engineering, Surveying, Geotechnical,
Permitting & Construction Management
15 %
$17,185
PROJECT TOTAL $131,749
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 38
6.7.4 Priority
A MEDIUM priority is assigned to this project because of the depth of street flooding.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 39
6.8 PROJECT 4– Delta Place & Riverwood Drive (City Project)
6.8.1 Description
At the upstream end of this small system there is a 4 foot x 4 foot box culvert (MZ57) with a collapsed
inlet. The box culvert empties into a 15 foot long improved open channel (MZ117) that leads to a 30 inch
corrugated metal pipe (MZ56). Modeling predicts that this last link surcharges in the 10-year event and
that the stormwater flows overland during events greater than the 25-year storm.
However modeling may not be predicting the true extent of the problem as the homeowner on the east
side of this small system reports yard flooding more than ten times in ten years, and water has gotten into
the house through a low walkout door on the back side of the house.
This excessive flooding is probably due to the obstructed box culvert and the lack of a well defined swale
that would convey the water downstream.
6.8.2 Recommended Improvement
This small system should be replaced from the uphill inlet to the far side of Delta Place with 36 inch pipe.
This will give the City an opportunity to bury the open channel portion of the system, establish an inlet
with proper elevation, headwall, and grading, and provide a side yard swale so that it can handle flow
when the system becomes obstructed or when larger storms than the design storm occur.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 40
6.8.3 Cost Opinion
Description Quan. Unit Unit Price Total Cost
Delta Place
Remove Existing Pipe 230 LF $14.05 $3,232
Excavation 774 CY $4.92 $3,808
Bedding 174 CY $40.00 $6,960
Material to be hauled off site 48 CY $9.70 $469
Backfill and compaction 540 CY $28.15 $15,201
36" RCP 230 LF $50.50 $11,615
Inlet structure 3 ea $5,090.00 $15,270
Finish Grading 816 SY $4.00 $3,264
Hydromulching 7350 SF $0.44 $3,234
Subtotal $63,052
Erosion Control 5 % $3,153
Mobilization / Demobilization 1 % $631
Traffic Control 2 % $1,261
Utility Relocation 2 % $1,261
Subtotal $69,357
Contingency 25 % $17,339
Construction Total $86,697
Engineering, Surveying, Geotechnical,
Permitting & Construction Management
10 %
$8,670
PROJECT TOTAL $95,366
6.8.4 Priority
A LOW priority is assigned to this project because the problem is primarily yard flooding.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 41
6.9 PROJECT 5 – State Street & Marshall Street (City Project)
6.9.1 Description
The modeling suggests that this system exceeds the desired capacity for events greater than the 10-year
storm event, as indicated by surcharging (see Figure 6-5), however no complaints have been reported.
This would not necessarily be a problem, except that there is no alternative pathway for water to drain
from the site. There is a difference of about twelve feet between the elevation of State Street and the area
drain in this sump, but only about two feet of elevation before ponding water can enter the basement of
the warehouse.
6.9.2 Recommended Improvement
This site is sensitive to obstruction from silt and debris and should be inspected regularly.
6.9.3 Priority
A REVIEW DURING FUTURE DEVELOPMENT priority is assigned to this project because the
system is surcharging in this location.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 42
6.10 PROJECT 6– Algoa Area (City Project)
6.10.1 Description
Surcharging occurs in the 25-year event at a number of locations in the Algoa area. Most of these sites
are private or state owned facilities and were not subject to City regulation when they were built. See
Figure 6-6, or see Exhibits 8B and 8C for a larger view of these sites.
6.10.2 Recommended Improvement
Future development should not add any demand to these conveyances that are already at or beyond their
capacities.
6.10.3 Priority
A REVIEW DURING FUTURE DEVELOPMENT priority is assigned to this project because the
system there is surcharging in this location.
Missouri River and Algoa Study Area Stormwater Master Plan
City of Jefferson, Missouri
November 18, 2005 49
SECTION 7.0 - GLOSSARY OF TERMS
7.1 DEFINITIONS
10-year Event - An event (such as rainfall or runoff) having a 10% (1/10) probability of being
exceeded in any given year.
25-year Event - An event (such as rainfall or runoff) having a 4% (1/25) probability of being
exceeded in any given year.
50-year Event - An event (such as rainfall or runoff) having a 2% (1/50) probability of being
exceeded in any given year.
100-year Event - An event (such as rainfall or runoff) having a 10% (1/100) probability of being
exceeded in any given year.
Design Criteria - Guidelines upon which planning and engineering decisions and judgments are
based.
Design Storm - A precipitation event that, statistically, has a specified probability of occurring in
any given year (expressed either in years or as a percentage).
Detention Facility - Any structure, device or combination thereof, that functions to accept inflow
from surface runoff and discharge it at a controlled rate less than the peak inflow rate.
Development - Any activity that alters the surface of the land that generally creates additional
impervious surfaces including, but not limited to, pavement, buildings and structures.
Drainage - Interception, collection and removal of excess stormwater from an area into another area
or into a receiving water body.
Enclosed Drainage System - A drainage system consisting of essentially continuous pipes and/or
box culverts below the ground surface.
Erosion - The removal of soil particles by the action of flowing water.
Excess Runoff - Direct surface runoff that cannot be accommodated satisfactorily by the existing or
planned drainage system.
Flood Control - Preventing the entry of stormwater into an area from another area, or from a stream
or other water body.
Floodplain - The area surrounding a watercourse that is inundated with floodwater.
Flood Routing - An analytical technique used to compute the effects of system storage and system
dynamics on the shape and movement of a flood wave.
Floodway - A tool or concept used by local communities for flood plan management. The area of
the 100-year flood plain is divided into a floodway and floodway fringe. The floodway is the
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channel of the stream plus any adjacent flood plain areas that must be kept free of encroachment
to that the 100-year flood can be carried without substantial increases in flood height. Minimum
Federal standards limit such increases to 1.0 foot, provided hazardous velocities are not exceeded.
Freeboard - The vertical difference in elevation between the hydraulic gradient and a referenced
point. Examples are the difference between the maximum water surface level behind a dam and
the top of a dam, or the difference in elevation between the water surface at a culvert beneath the
roadway and the surface of the roadway.
Head - The difference in depth of a liquid at two given points; a depth generally expressed in feet.
HEC-RAS - United States Corps of Engineers Hydrologic Engineering Center’s program for
modelling water surface profiles in open channels, River Analysis System.
Hydraulic Gradient - The elevation of the surface of the water in the drainage system at any point.
Hydrograph - A graph of runoff rate, inflow rate or discharge rate, versus time.
Hydrologic Soil groups - A soil characteristic classification system defined by the U.S. Soil
Conservation Service in which a soil may be categorized into one of four soil groups (A, B, C, or
D) based upon infiltration rate and other properties.
Impervious Surface - Any surface that does not readily permit water to infiltrate. Examples are
roofs and concrete or asphalt-paved surfaces.
Improved Channel - Any channel whose characteristics are changed by either grading or
construction of lining materials.
Interception - Rainfall that is caught by foliage, branches, leaves, and other aboveground objects.
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Lag - The time interval from the center of mass of excess rainfall to the peak rate of runoff.
Level of Service - The return period for which a drainage system, or an individual element of that
system, has adequate hydraulic capacity.
Master Planning - A “systems” approach to the planning of facilities, programs and management
organizations for comprehensive control and use of stormwater within a defined geographical
area.
Natural Channel - An existing channel that has not been appreciably altered by grading, lining or
changing its course.
Open System - A drainage system consisting of open channels, either natural or improved, with only
comparatively short lengths enclosed by pipes or culverts.
Pervious Surfaces - Surfaces that absorb water such as undeveloped areas, fields, yards and other
unpaved areas.
Reach - A specific length of the storm drainage system between two points. For example, a reach
may consist of a single culvert or may consist of several connected pipes or channel sections.
The term "line" may also be used synonymously within the report.
Receiving Waters - Streams, lakes, bays, etc., into which stormwaters are discharged.
Return Period - A statistical term for the average frequency that a given event may be expected to
occur, although it does not imply that the event will occur regularly at even intervals. It can also
be defined as the reciprocal of the probability of an event. For example, a storm having a 10-year
return period statistically can be expected to occur once in a period of 10 years, a probability of
occurrence of 0.10, or 10%. However, the event may occur at any time, and two such events may
actually occur on successive days.
Sediment - Soil particles eroded by flowing water; either in suspension in that water or as deposited.
Storm Drainage System - Natural or constructed facilities and appurtenances, such as ditches,
natural channels, pipes, culverts, bridges, improved channels, street gutters, inlets and detention
facilities, which serve to collect and convey surface drainage.
Storm Sewers - Usually, enclosed conduits that transport excess stormwater runoff toward points of
discharge (sometimes call “storm drains”).
Stormwater Management - Encompasses both “control” and “developmental” activities in which
there is physical interaction with stormwater (a broader interpretation includes activities of an
institutional nature – financing, staffing, etc.).
Stormwater Storage - Temporary storage of excess runoff on, below, or above the surface of the
earth for the purpose of attenuating excess runoff.
Time Of Concentration - The time period necessary for surface runoff to reach the outlet of a sub-
basin from the hydraulically most remote point in the tributary drainage area.
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Travel Time - The sum of the time intervals for overland flow, sewer or gutter flow, and pipe and
channel flow from the hydraulically most remote point in the tributary to the discharge point of
interest.
Watershed - All land draining to the storm drainage system at any given point. This term is used
synonymously with the terms tributary area, drainage area, drainage basin, catchment area,
subwatershed and subarea.
Water Surface Profile (Existing) - the “Existing” water surface profiles represent flooding
conditions based on current land use conditions within the study area.
Water Surface Profile (Future) - the “Future” water surface profiles represent flooding conditions
based on future land use conditions within the study area.
7.2 ACRONYMS
APWA - American Public Works Association
cfs – Cubic feet per second
CMP - Corrugated metal pipe
CMPA – Corrugated metal pipe arch
DTM - Digital Terrain Model
EPA – Environmental Protection Agency
FEMA - Federal Emergency Management Agency
FIS - Flood Insurance Study
GIS - Geographic Information System
HEC – Hydrologic Engineering Center (U.S. Army Corps of Engineers)
MDNR – Missouri Department of Natural Resources
MoDOT – Missouri Department of Transportation
NFIP - National Flood Insurance Program
RCB – Reinforced Concrete Box
RCP – Reinforced Concrete Pipe
SWMM – Storm Water Management Model
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TIN - Triangulated Irregular Network
USACE - Unites States Army Corps of Engineer