constructed wetlands final project report with final edits 4-27-11 (1)
TRANSCRIPT
Rick Hollander
Noah Posthuma
Arturo Roberto Huesca Santos
Final Project Report
NRE 501: Constructed Wetlands
Professor Christopher Ellis
School of Natural Resources and Environment
University of Michigan
April 27, 2011
Constructed Stormwater Pocket Wetland System for Site 5 – Botanical Gardens North
1
Acknowledgments
We would like to acknowledge the considerable time, attention to detail and remarkable
clarity of communication offered by Professor Christopher Ellis in advising on constructed
wetland design solutions, and providing invaluable insights and information on resources,
including a suggested a tour of the infiltration swale at West Park in Ann Arbor, and a guided
tour of the extended detention stormwater wetland in Doyle Park, Ann Arbor. In addition, the
course lectures and reading list for NRE 501 – Constructed Wetlands provided the knowledge
base for the entire project.
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Executive Summary
This report describes a stormwater constructed wetland project designed to treat runoff
for a 2-year storm in the Botanical Gardens North catchment area in Ann Arbor, Michigan. The
catchment size and configuration posed design challenges, as well as an opportunity, to create a
pocket wetland treatment train that accomplished the required treatment of the desired water
quality volume, WQv, while also allowing for a sufficient dewatering time. Such dewatering
time needed to provide for both adequate residence time for runoff to be treated as well as
sequentially lengthening inundation periods for which wetland plants could be selected that best
met environmental constraints. Finally, the selection of wetland plants, and other physical
design characteristics of the engineered solution – a four-cell pocket wetland – were chosen,
along with a maintenance plan, to provide an important amenity for the surrounding community,
ensuring support for eventual wetland construction and ongoing maintenance. Further analysis
should be conducted to determine the feasibility of creating an offline wetland structure within
the catchment in order to avoid the cost and administrative complexity of obtaining required
permits and constructing wetland mitigation for the existing stream/wetland in the catchment.
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Table of Contents
Introduction……………………………………………………………….6
Description of the catchment……………………………………………..8
Modelling WQv…....................................................................................16
Estimation of contaminant loading and removal…………………………24
Master plan………………………………………………………………..26
Plant schedule……………………………………………………………..36
Conclusions……………………………………………………………….40
References…………………………………………………………………42
Appendices………………………………………………………………...43
4
Lists of Figures, Maps, Tables, Exhibits
Figures 1 and 2: Commercial Area in the Upper Part of the Catchment (Domino’s Headquarters) and Infiltration Pond for Domino’s Parking Lot………………………………………….11
Figures 3 and 4: Upper Part of the Catchment with Stump-Sprouted Deciduous Forest Growth (American Elms), and an Artificial Pond Surrounded by Scots Pine (Pinus sylvestris)…..12
Figures 5 and 6: Upper Part of the Catchment Showing Riverine Forest (Poplars and Elms) at Plymouth Road Intersection (with Earthen Embankment Sloping Down from Plymouth Road Shoulder in Foreground in Left Picture)……………………………………………………13
Figures 7 and 8: Middle Area of Catchment (South of Plymouth Road) Showing Permanent Water Flow and Pasture Land…………………………………………………………………14
Figure 9: Lower Part of Catchment; Single-Family Residential Developments Are Present On Either Sides of the Creek……………………………………………………………………..14
Figure 10: Single-Family Residential Development in Lower Part of Catchment…………..15
Figure 11: Catchment Outlet at Dixboro Road………………………………………………15
Figure 12: Catchment Plan View with Contour Lines……………………………………….17
Figure 13: Catchment Lateral View with Contour Lines……………………………………..17
Figure 14: Plan View of Four-Cell, Pocket Wetland, Situated Within the Catchment……….28
Figure 15: Designing Pocket Wetland 1………………………………………………………30
Figure 16: Designing Pocket Wetland 2………………………………………………………30
Figure 17: Designing Pocket Wetland 3……………………………………………………….31
Figure 18: Designing Pocket Wetland 4……………………………………………………….31
Figure 19: Pocket Wetland 1 Diagram…………………………………………………………32
Figure 20: Pocket Wetland 2 Diagram………………………………………………………….33
Figure 21: Pocket Wetland 3 Diagram…………………………………………………………..34
Figure 22: Pocket Wetland 4 Diagram…………………………………………………………..35
Figure 23: Plant species selected for aesthetic value (Iris versicolor)……………………….36
Figure 24: Peltandra virginica. Rhizomatous plant suitable for wildlife food and cover……37
Figure 25: Eutrophication problems…………………………………………………………..37
Figure 26: Cattail (Typha latifolia), for Nitrogen, Nitrate, Ammonia and Phosphate ……….38
5
Map 1: Catchment Location in Ann Arbor…………………………………………………8
Map 2: Catchment Area Land Use Types. …………………………………………………9
Map 3: Catchment Area by Hydrological Soil Types, A-D………………………………..10
Exhibit 1: Win TR-55 Data description ……………………………………………………18
Exhibit 2: Hydrograph for 2-year storm for Pocket Wetland Storm Water Constructed Wetland with 6-Inch Diameter Pipe…………………………………………………………………..21
Exhibit 3: Hydrograph for 2-year storm for Pocket Wetland Storm Water Constructed Wetland with 8-Inch Diameter Pipe. ………………………………………………………………….22
Exhibit 4: Hydrograph for 2-year storm for Pocket Wetland Storm Water Constructed Wetland with 10-Inch Diameter Pipe. …………………………………………………………………23
Exhibit 5: TR-55 Model Run for 2-Year Storm for Calculation of WQv, Peak Flow Time, and Dewatering Time for Pocket Wetland Structure with 8-inch Diameter Outlet Pipe. …………………………….43
Table 1: Time of Concentration Details…………………………………………………….19
Table 2: Estimation of Contaminant Loading……………………………………………….24
Table 3: Estimation of Contaminant Removal……………………………………………… 25
Table 4: Stormwater treatment control and practices………………………………………..26
Table 5: Pond Vegetation at Various Depths ……………………………………………….37
Table 6: Species for Lower and Upper Marsh Zones, and Buffer Zone ……………………39
6
Introduction
The unique challenges and characteristics of the catchment include a long, but narrow,
catchment area, with a relatively steeply sloped catchment width, but also a low gradient of
catchment/channel length. The catchment configuration constrains the size of the treatment
structure. Moreover, the source of channel flow, as described more fully in the Master Plan
section, is primarily groundwater. These two constraints – physical configuration and water
source – are ideally suited for a treatment train, consisting of a series of pocket wetlands (C.
Campbell and M. Ogden 1999).
In addition to management of stormwater flow and avoidance of flooding, the constructed
wetland design and plant schedule must also provide for contaminant removal from runoff for
not only existing development in the catchment, but also future development in the catchment.
56% of the area is largely undeveloped, mostly forested, land.
Another major category of goals for the constructed wetland centers on providing an
amenity for the surrounding community, which not only increases property values for
landowners in and around the catchment, but also provides for high aesthetic values as well as
habitat to attract birds and wildlife. Objectives that can achieve the “amenity” goal would
include incorporating: ornamental plants into the wetland design, plants that provide for food
and cover for animals, plants that oxygenate water but inhibit algal growth, and plants that attract
wildlife which will keep mosquito populations under control, given the proximity of residential
development to the constructed wetland (C. Campbell and M. Ogden 1999). By having the
constructed wetland be an amenity for the community, and not just an engineering solutions for
stormwater treatment, there will be continued community support for developing the wetland
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master plan and providing for ongoing maintenance. Ongoing maintenance could incorporate
educational components, as well as local residents volunteering for maintenance work.
A final, major goal will be designing the wetland for safety, which can be achieved by
including design features, such as safety benches and appropriate slopes for pool edges, as well
having a thorough, ongoing maintenance plan (C. Campbell and M. Ogden 1999).
Description of the Catchment
The project is a suburban catchment in northeast Ann Arbor, Michigan. The total surface
of the catchment is 264 acres articulated around a forested creek that starts at Domino’s
corporate headquarters, draining towards Dixboro Road into a relatively flat marsh system. The
marsh system ultimately drains into the Huron River.
Map 1: Catchment Location in Ann Arbor. Source: Washtenaw County.
8
Map 2: Catchment Area Land Use Types. Source: Washtenaw County.
9
Map 3: Catchment Area by Hydrological Soil Types, A-D. Source: Washtenaw County.
Note that Washtenaw County GIS data indicated that soil types B and D, which also
contain roads with impervious, paved surfaces, were classified as “B/D” and “A/D,”
respectively.
10
Land cover for 56% of the catchment is predominantly irregular deciduous forest with
some Scots pine trees in the upper part of the catchment, and a riverine forest on both sides of a
creek with permanent water flow. Vegetative regeneration from root and stump sprouts appears
in some areas, generating a very dense and old forest structure. This regeneration has likely
happened as a result of human disturbance, such as wild fires and fuel wood harvesting in past
decades. Other areas of the forest have a more conventional regular structure with the presence
of seedlings, saplings and mature trees – mostly deciduous species, with Scots pines scattered
throughout. Lack of silvicultural practices, such as thinning in the forest or maintenance pruning
on both sides of gravel roads to prevent forest fires may reduce resilience of these very disturbed
woods.
Figures 1 and 2: Commercial Area in the Upper Part of the Catchment (Domino’s Headquarters)
and Infiltration Pond for Domino’s Parking Lot
11
Figures 3 and 4: Upper Part of the Catchment with Stump-Sprouted Deciduous Forest Growth
(American Elms), and an Artificial Pond Surrounded by Scots Pine (Pinus sylvestris).
Figures 5 and 6: Upper Part of the Catchment Showing Riverine Forest (Poplars and Elms) at
Plymouth Road Intersection (with Earthen Embankment Sloping Down from Plymouth Road
Shoulder in Foreground in Left Picture).
12
Figures 7 and 8: Middle Area of Catchment (South of Plymouth Road) Showing Permanent
Water Flow and Pasture Land
The understory is very dense where the slope exposition is to the west or southwest, and
these forest areas are very difficult to walk through. Invasive species are also present throughout
these areas. Pasture is also present at the western side of the creek, mainly colonizing disturbed
soil after a sewage line had been installed, which runs roughly parallel to the creek, and services
either Domino’s headquarters or University of Michigan facilities. Despite being covered by
herbs and other grasses, some erosion in the form of gullies is present on this disturbed site.
The hydrological soil group under forest cover is mostly type B, but 7% of the forested
cover consists of type A soils, which contain the riverine forests. The dominant tree species in
the upper part of the catchment are Scots pine (Pinus sylvestris) and American elm (Ulmus
americana), which form a dense canopy, with 100% of soil covered by tree canopies. Natural
succession is occurring in gaps caused by the falling of dead trees, mainly Scots pine, which are
infected by a nematode. Other conifer species growing in the site include: eastern red cedar
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(Juniperus virginiana), Norway spruce (Picea abies), white spruce (Picea glauca) and green
spruce (Picea pungens). Apparently no forestry activities are carried out in the area and
colonization of forest gaps is the only method of forest regeneration. There is no major erosion
apparent in the upper part of the catchment (north of Plymouth Road); however, some severe
erosive channels or gullies were present in the earthen embankment sloping down from
Plymouth Road down to the creek.
The remaining 44% of the catchment area is commercial, streets and roads, and
residential single-family development (which contain approximately quarter-acre lot sizes).
Commercial areas cover 9% of total surface (24 acres), and consist chiefly of parking lots for
Domino’s corporate headquarters in the upper part of the catchment, as well as a University of
Michigan Computer Services facility. Streets and roads cover almost 7% of the catchment (19
acres), and residential single-family development in the lower part of the catchment covers 27%
of the total surface. All of these land uses areas contain primarily hydrological type-B soils.
Figure 9: Lower Part of Catchment; Single-Family Residential Developments Are Present On
Either Sides of the Creek.
14
Figure 10: Single-Family Residential Development in Lower Part of Catchment.
Figure 11: Catchment Outlet at Dixboro Road.
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Modeling WQv
TR-55 was used to model WQv and generate hydrographs. Hydrographs for a 2-year
storm for the chosen design, a four-cell stormwater constructed pocket wetland (see Master Plan
section below for design details), for three different scenarios for outlet pipe diameter are
presented in Exhibits 1 to 4, and Table 1, respectively. Peak flow occurs within 12-14 hours.
The total surface area of the four-cell pocket wetland is 10.045 acres. With an average water
depth over this surface area of 1 foot, WQv is 10.045 acre-feet of water.
The summary statistics for the catchment, including area of each land use sub-area,
runoff curve number by land use type, catchment time of concentration (Tc), and rainfall depth
for a 2-year storm for this catchment are presented in Exhibit 1. Note, the total catchment area is
264 acres, or 0.413 square miles, and the average runoff depth of the 2-year storm is 0.452
inches. The residential component of the catchment consists of 72 acres, with a density of 0.25
acre lot sizes. The commercial component is 24 acres, which includes the Domino’s corporate
headquarters buildings and parking lots, University of Michigan-owned commercial buildings
and parking lots, and a private, non-University-affiliated grammar/high school. The third
component, roads and streets, includes Plymouth Road and Dixboro Road, covering 19 acres.
The fourth component, the largest, is open space of 149 acres, with forest covering an area equal
to 56% of the total catchment space, and the balance being grass-covered fields.
Table 1 provides time of concentration details, including the length of the flow path from
the top of the catchment to the outlet, the length of each segment of the path by flow type, the
path slope by flow type, the Manning’s coefficient by flow type, and Tc by path segment, along
with details of the channel portion of the flow path. The total channel length is 7,547 feet, with a
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small gradient from the upper catchment to the outlet of approximately 110 feet. Figure 12
provides a plan view of the catchment with 2 foot contour lines outlining the channel path.
Figure 13 provides a lateral view of the catchment with contour lines, indicated the relatively
steep slope of the catchment width, and the shallow slope of the catchment length.
Figure 12 Catchment Plan View with Contour Lines
Figure 13 Catchment Lateral View with Contour Lines
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Exhibit 1 Win TR-55 Data description. Source: TR-55
WinTR-55 Current Data Description
--- Sub-Area Data ---
Name Description Reach Area(ac) Runoff Tc (hrs)
Curve
Number
---------------------------------------------------------------------------------------
Open Space (grass and Wetland 148.85 59
forest cover)
Commercial Wetland 23.84 92
Streets (paved and gravel) Wetland 19.17 95
Residential (0.25 acre Wetland 72.14 75
density)
Total area: 264 (ac) 1.764
Exhibit 1 continued
--- Storm Data --
Rainfall Depth by Rainfall Return Period
2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr
(in) (in) (in) (in) (in) (in)
--------------------------------------------------------------------------------
2.26 2.75 3.13 3.6 3.98 4.36
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Table 1. Time of Concentration Details. Source: TR-55
Path Flow Type
Length (ft)
Slope (ft/ft)
Surface Manning’s Coeff.
n
Area (ft2)
Wetted Perimeter
(ft)
Velocity (f/s)
Tc (hrs)
Sheet 100 0.0010 Grass 0.41 1.440Shallow Concentrated
888 0.0427 Unpaved, forest
0.074
Channel 6,559 0.0156 0.022 4.00 5.00 7.288 0.250Total 7,547 1.1884 1.764
Exhibits 2 to 4 present hydrographs and the TR-55 model run (the model run is contained
in the Appendix) to calculate for the 2-year storm for the pocket wetland structure: WQv, peak
flow time, and the time to de-water. The peak flow time is approximately 13 hours, and the
pocket wetland substantially de-waters in 48 hours, with total de-watering within 70 hours.
Three outlet pipe diameters were analyzed: a 6-inch, 8-inch and 10-inch. The desired de-
watering time is 48 hours, so that the constructed wetland has a storm water residence time that
is sufficient for contaminant removal, yet not so long as to kill wetland plants. The 8-inch
diameter outlet pipe was selected, in order to achieve a 48-hour dewatering time, which balances
the need for water treatment against the risk of financial loss associated damaging wetland
plants.
Note that a modeling simplification was used in TR-55 to model the dewatering time of
the constructed pocket wetland. As described more fully in the Master Plan section below, the
constructed wetland consists of a series of 4 pocket wetlands that are linked in a treatment train
along the channel area of the catchment to the outlet. The overall treatment structure would be
modeled in TR-55 as 4 sub-catchments, each one feeding into a pocket wetland cell (sub-
structure), which is connected by a reach to the next cell in the treatment train. Because runoff
flows sequentially from one sub-catchment cell to the next, the residence time of runoff increases
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in length going from the first cell to the next, with the fourth cell (connected to the outlet) having
the longest residence time (in other words, each cell has a different hydrograph). This increasing
residence time for the water (or dewatering time) in each sequential pocket wetland cell would
result in a different plant schedule for each cell, based upon tolerance for inundation and ability
to remove contaminants during inundation. However, the analysis in this report is based on a
modeling short-cut or simplification, in which a single catchment and treatment cell (ie, one sub-
structure) is modeled in TR-55, and connected to the outlet. The overall dewatering time for the
treatment train of 4 cells should not differ materially from the dewatering time for the single cell.
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Exhibit 2. Hydrograph for 2-year storm for Pocket Wetland Storm Water Constructed Wetland
with 6-Inch Diameter Pipe. Source: TR-55.
21
Exhibit 3. Hydrograph for 2-year storm for Pocket Wetland Storm Water Constructed Wetland with 8-Inch Diameter Pipe. Source: TR-55.
22
Exhibit 4. Hydrograph for 2-year storm for Pocket Wetland Storm Water Constructed Wetland with 10-Inch Diameter Pipe. Source: TR-55.
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Estimation of Contaminant Loading and Removal
Table 2: Estimation of Contaminant Loading
Sources for loading calculations: Claytor and Schueler (1996), Steuer et al. (1997), Bannerman 1993), Caraco (2001), Camp et al. (2004), Marsh (2010).
LOADING
Land Use Acres Phosphorus Loading Nitrogen Loading TSS Loading
pounds per acre per year per land use
pounds per acre per year per land use
tons per acre per
yearpounds per year
pounds per year
tons per year
Residential
0.5 units/acre 0.8 6.2 0.09
1 units/acre 0.8 6.7 0.11
2 units/acre 0.9 7.7 0.14
10 units/acre** 72.144 1.5 108.216 12.1 872.942 0.27 19.479
Commercial 23.84 0.7 16.69 7.1 169.264 0.08 1.907
Industrial 0.7 9.5 0.15
Roads 19.17 0.8 15.336 7 134.19 0.14 2.684
Ag/Pasture 0.7 12.4 0.15
Forest 148.846 0.2 29.769 5.5 818.653 0.05 7.4423
Total 264.0 170.0 1,995.1 31.5
____________________
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** Note lot sizes for residential units were estimated as 0.25 acres/unit; thus, assuming 10 units/acre or 0.10 acre lot sizes is conservative (ie, overestimates contaminant loading for purposes of designing phytoremediating plant schedule).
Table 3: Estimation of Contaminant Removal
For pocket wetland system for phosphorus, nitrogen, and TSS (based upon Table 14.3 below (J. Randolph 2004))
REMOVAL
Phosphorus Nitrogen TSS
pounds per acre per
year
pounds per acre per year
Tons per acre per
year
96.9 877.8 18.0
25
Table 4: Table 14.3 (J. Randolph 2004)
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Master Plan
As indicated in the Introduction section, the unique features and challenges of the catchment
include the fact that it is quite long, but also narrow and with a steeply sloped width. These
physical characteristics constrain the size of the treatment cells, and require a treatment train of
pocket wetlands, which would have the following benefits:
occupy less surface area than extended detention wetlands, pond/wetlands or a shallow
marsh system (C. Campbell and M. Ogden 1999); and,
are ideal where a high water table or groundwater maintains the wetland pools
(Maryland Department of the Environment 2009).
Visual inspection of the “headwaters” of the upper catchment confirmed that neither a pond,
stream, river, nor other above-ground body of water was the source of the channel flow in the
catchment. Instead, at the very top of the catchment, water, rather audibly, was found to be
rushing from underground, and a stream was daylighting. Hence the source of the channel flow
was confirmed to be groundwater, which is ideally-suited for a pocket constructed wetland
(Maryland Department of the Environment 2009). Furthermore, because of the restrictions on
space, and in order to take advantage of the existing contour lines, a treatment train of pocket
wetlands was used to treat the full WQv, as shown in Figure 14 below. In addition, because the
goals of the stormwater wetland include removing contaminants from runoff from both existing
commercial and residential development in the catchment, as well future additional development,
a treatment train rather than a single-cell system was chosen.
27
Figure 14. Plan View of Four-Cell, Pocket Wetland, Situated Within the Catchment
As illustrated in Figures 15 to 18, the existing contour lines were used to bound the 4
pocket wetland cells. In cells 1, 3 and 4, contour lines were connected to form embankments to
bound the cells, where existing contour lines formed polygons that were too long. Following the
upper end of the suggested range for pocket wetlands identified by Campbell and Ogden, the
total surface area of the 4 pocket wetlands was capped at approximately 10 acres. Since the
WQv for the 2-year storm was calculated using TR-55 to be approximately 10 acre-feet, the
average water depth of the 4 pockets wetlands, inclusive of sediment forebays, micropools, and
high/low marsh, is 1 foot. The Maryland Department of Environment Stormwater Design
Manual was used as the guide for designing the 4 pocket wetlands, including the following
elements in each cell: sediment forebay and micropool, high marsh and low marsh zones, a
28
buffer surrounding each cell, safety bench surrounding each cell as well as the forebay and
micropool, barrel riser with trash rack in micropool, use of a broad-crested weir on the
embankment, use of a stable inflow and outflow, maintenance access, and use of a vegetated
swales (W. Marsh 2010) as the reach connecting each pocket wetland. Vegetated swales are
used to maximize infiltration (Maryland Department of the Environment 2009).
The sediment forebays and micropools were designed to be 4 feet in depth to prevent low
flow pipes from clogging and to avoid sediment re-suspension (Maryland Department of the
Environment 2009). Forebays were installed with drain pipes so that they can be drained within
24 hours. The combined surface area of the forebays and micropools was set so that at least 25%
of total WQv would be contained in the pools (Maryland Department of the Environment 2009).
The high marsh zone areas were sized so that at least 35% of the total pocket wetland surface
area would be a depth of six inches or less, and the low marsh zones were sized so
that at least 65% of the total surface area would be shallower than 18 inches
(Maryland Department of the Environment 2009).
The sediment forebays and micropools were designed with a
reasonable safety factor to manage liability issues, including a safety bench
around each pool, planted with emergent plants, such as cattails to inhibit
people from entering the pools (see Plant Schedule for further information),
and pond edges with slopes no greater than 3:1 (C. Campbell and M. Ogden
1999).
29
Figure 15. Designing Pocket Wetland 1
Figure 16. Designing Pocket Wetland 2
30
Figure 17. Designing Pocket Wetland 3
Figure 18. Designing Pocket Wetland 4
31
Figure 19. Pocket Wetland 1 Diagram
32
Figure 20. Pocket Wetland 2 Diagram
33
Figure 21. Pocket Wetland 3 Diagram
34
Figure 22. Pocket Wetland 4 Diagram
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Plant Schedule
Because the goals of the constructed wetland system include providing for an amenity for
the surrounding community, in addition to an engineered stormwater solution, the plant schedule
is designed, in part, to provide strong visual appeal, as well as providing habitat for waterfowl
and wildlife, and to control unsightly algal growth.
Species have been selected according to the water depth, and the species list provided
below in Table 5 includes plant species with phytoremediation properties to treat pollutants like
nitrogen compounds, phosphorous and total suspended solids. For aesthetic purposes, a selection
of species for the high marsh should include Iris versicolor, whose flower’s color would add
aesthetic value to the wetland. To promote wildlife cover and feed, species like Peltandra
virnica, Decodon verticillatus and Eupatorium perfoliatum have been selected for planting in
shallow waters (0-6 in). As part of the strategy design to manage nutrient load and prevent
eutrophication, floating species have been selected to reduce pond water column temperature
(Nuphar lutea and Lemna minor) as well as submerged species to aerate the water (Elodea
cadadensis). (Interstate Technology and Regulatory Council 2009)
Figure 23. Plant species selected for aesthetic value (Iris versicolor)
36
Figure 24. Peltandra virginica. Rhizomatous plant suitable for wildlife food and cover
Figure 25. Eutrophication problems
Table 5: Pond Vegetation at Various Depths. Source: (Christopher Ellis 2011)
0-6 inches (0-15 cm) 6-18 in (15-45 cm) >18 in (>45 cm)Acorus calamus (full sun, no drought)
Nuphar lutea variegate (Floating, growing to height of up to 7 feet, likes sun or shade, food/cover for wildlife)
Elodea canadensis (good for water aeration)
Peltandra virginica (sun or shade, food/cover for wildlife)
Lemna minor Lemna minor
Eupatorium perfoliatum (perennial, full sun, food for birds and pollinators)
Cattails (Typha latifolia) Cattails (Typha latifolia)
Tussock sedge (Carex stricta)
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Inorganic pollutants of main concern are heavy metals and nutrients. The primary
inorganic pollutants of concern in urban stormwater include: cadmium, copper, lead, zinc,
nitrogen, nitrate, ammonia, phosphorous and phosphate. Plant species included in the schedule
(not necessarily native) with phytoremediation capabilities are:
Figure 26. Cattail (Typha latifolia), for Nitrogen, Nitrate, Ammonia and Phosphate
Grey willow (Salix cinerea): tree species, tolerates swampy grounds, good for the forest buffer.
Flatsedge (cyperus spp): originally from Egypt; prefers up to 18 inches of depth
Additional species that can be used in the lower and upper marsh zones, and in the buffer
zone, according to the Phytotechnology Technical and Regulatory Guidance and Decision Tree
(Interstate Technology and Regulatory Council 2009), are presented below in Table 6.
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Table 6: Species for Lower and Upper Marsh Zones, and Buffer Zone (Interstate Technology
and Regulatory Council 2009)
POLLUTANT SPECIES REMEDIATION YIELD
REFERENCE
NH4 Meadow rush and salt grass(Juncus spp. and Distichlisspicata)
Decreased concentrations from 14.1 to 0.1 mg/L (near naturalbackground)
Kadlec and Knight 1996
NH4 Hybrid poplars (Populus spp.)
Decreased groundwater concentrations from 140 to 20 mg/kg in1 year
Applied Natural Sciences, Inc.1997
NO3 Meadow rush and salt grass(Juncus spp. and Distichlisspicata)
Decreased concentrations from 41 to 0.6 mg/L (below naturalbackground)
Kadlec and Knight 1996
NO3 Hybrid poplars (Populus spp.)
Decreased groundwater concentrations by over 100 mg/kgcompared to unvegetated areas
Applied Natural Sciences, Inc.1997
Total suspended solids
Bulrush and cattail (Scirpusand Typha spp.)
35 mg/L influent reduced to 5 mg/L at effluent
Kadlec and Knight 1996
Total suspended solids
Multiple wetland species(specific types notreported)
Average reduction from 40.4 to 14.1 mg/L for 2 years
Kadlec and Knight 1996
Maintenance Plan
Regardless of the treatment objective, management activities for the cells are similar and
include maintenance of water uniformity, management of vegetation, control of odor, pests and
insects, and structural integrity of berms and embankments (Interstate Technology and
Regulation Council 2003). Proper maintenance of the inlet/outlet piping will ensure that earthen
39
structures do not clog, thereby ensuring proper water level and flow. Maintenance includes
physical removal of trapped sediment, flushing of pipes and the use of high pressure water spray
for cleaning (Interstate Technology and Regulation Council 2003). Once or twice every year,
depending on the amount of sediments carried towards our wetland, the sediment forebays must
be cleaned and toxic sediments must be properly landfilled as necessary.
It will be desirable to coordinate with the City of Ann Arbor, and perhaps the Huron
River Watershed Council, for the use of volunteer coordinators for removing any trash, as well
as invasive species. Volunteer efforts have been a successful, low-cost element of the
maintenance plans nearby at Matthei Botanical Gardens in Ann Arbor.
Nuisance pests like mosquitoes find a perfect breeding ground in permanent standing
water. In most parts of the country (including Michigan), mosquito fish (Gambusia affinis) have
proven to be very useful in controlling mosquito larvae (C. Campbell and M. Ogden 1999). The
use of insecticides is not advised due to persistence problems in wetland systems.
40
Conclusion
Stormwater wetlands may not be constructed within jurisdictional waters (including
wetlands) without first obtaining a CWA Section 404 permit and/or State of Michigan (and
perhaps county/local) wetlands and waterways permit(s). Moreover, these permit(s), if granted,
would nonetheless require mitigation. A lower cost approach to the stormwater wetland may be
to redesign it, so that the system is offline, but within the catchment (Maryland Department of
the Environment 2009). The catchment site would need to be analyzed to confirm that there is,
in fact, sufficient space to construct an offline system, and that other ecosystem damage (eg,
deforestation within the catchment, and habitat damage) can be minimized.
Assuming a multi-cell, treatment train would still be used, the structure should be
re-modeled in TR-55 to compute residence/dewatering times for each cell for a 2-year (and/or
other) storms, so that plants can be better selected that work best for varying periods of
inundation.
41
References
C. Campbell and M. Ogden. Constructed Wetlands in the Sustainable Landscape. New York: John Wiley & Sons, 1999.
Christopher Ellis. " In class lecture slides, "Constructed Wetlands 6- Plants (Revised)"." NRE 501 - Constructed Wetlands class lecture given by author. Ann Arbor: University of Michigan School of Natural Resources and Environment, 2011.
Interstate Technology and Regulation Council. Technical and Regulatory Guidance Document for Constructed Treatment Wetlands. Washington: Interstate Technology and Regulation Council, 2003.
Interstate Technology and Regulatory Council. Phytotechnology Technical and Regulatory Guidance and Decision Trees. Washington, 2009.
J. Randolph. Environmental Land Use Planning and Management. Washington, DC: Island Press, 2004.
Maryland Department of the Environment. Maryland Stormwater Design Manual, Volumes I and II. Maryland DOE, 2009.
W. Marsh. Landscape Planning - Environmental Applications. John Wiley & Sons, 2010.
42
Appendices
Exhibit 5: TR-55 Model Run for 2-Year Storm for Calculation of WQv, Peak Flow Time, and Dewatering Time for Pocket Wetland Structure with 8-inch Diameter Outlet Pipe. Source: TR-55.
WinTR-20 Printed Page File Beginning of Input Data List
TR20.inp
WinTR-20: Version 1.10
Dominos
SUB-AREA: Area (sq mi) RCN Tc
Open Space .23258 59 1.764
Commercial .03725 92 1.764
Streets .02995 95 1.764
Residential .11272 75 1.622
STREAM REACH:
Wetland Outlet Structure (name of Outlet structure)
STORM ANALYSIS:
2-Yr 2.26 in Type II 2
STRUCTURE RATING:
Structure (6-Inch Diameter Outlet Pipe)
0.00 0.000 0.00
0.25 2.107 2.50
0.50 2.159 5.00
1.00 2.260 10.00
2.50 2.538 25.00
5.00 2.943 50.00
10.00 3.620 100.00
43
A_Structure
0.00 0.000 0.00
0.25 3.715 2.50
0.50 3.808 5.00
1.00 3.989 10.00
2.50 4.485 25.00
5.00 5.209 50.00
10.00 6.417 100.00
B_Structure
0.00 0.000 0.00
0.25 5.756 2.50
0.50 5.903 5.00
1.00 6.186 10.00
2.50 6.968 25.00
5.00 8.105 50.00
10.00 9.998 100.00
ALTERNATE ANALYSIS:
Trial #2 Second possible alternative : 8-Inch Diameter Outlet Pipe
REACHES
Wetland Outlet A_Structure
Trial #3 Third possible alternative: 10-Inch Diameter Outlet Pipe
REACHES
Wetland Outlet B_Structure
GLOBAL OUTPUT:
2 0.05 YYYYN YYYYNN
44
WinTR-20 Printed Page File End of Input Data List
ALTERNATE Trial #2 STORM 2-Yr
Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
Open Space 0.233 0.097 14.07 1.82 7.82
Line
Start Time ------------ Flow Values @ time increment of 0.111 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
12.284 0.07 0.14 0.25 0.39 0.55 0.74 0.92
13.064 1.10 1.27 1.41 1.54 1.64 1.72 1.77
13.843 1.80 1.81 1.82 1.81 1.81 1.79 1.77
14.623 1.75 1.72 1.70 1.67 1.65 1.63 1.60
15.403 1.58 1.56 1.54 1.52 1.50 1.48 1.46
16.183 1.44 1.42 1.40 1.38 1.36 1.34 1.32
16.963 1.30 1.28 1.27 1.25 1.24 1.22 1.21
17.743 1.20 1.19 1.18 1.17 1.16 1.15 1.14
18.523 1.13 1.12 1.11 1.10 1.09 1.08 1.07
19.303 1.06 1.05 1.04 1.03 1.01 1.00 0.99
20.082 0.98 0.97 0.96 0.94 0.93 0.92 0.91
20.862 0.90 0.89 0.88 0.87 0.86 0.86 0.85
21.642 0.85 0.84 0.84 0.84 0.83 0.83 0.83
22.422 0.83 0.83 0.82 0.82 0.82 0.82 0.82
23.202 0.82 0.81 0.81 0.81 0.81 0.81 0.81
23.982 0.80 0.80 0.80 0.78 0.76 0.74 0.70
24.762 0.65 0.60 0.54 0.48 0.42 0.36 0.31
45
25.542 0.26 0.22 0.19 0.16 0.13 0.11 0.10
26.321 0.08 0.07 0.06 0.05
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Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
Commercial 0.037 1.470 12.96 12.83 344.39
Line
Start Time ------------ Flow Values @ time increment of 0.111 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
7.612 0.05 0.06 0.07 0.08 0.09 0.10 0.11
8.391 0.12 0.14 0.15 0.16 0.18 0.19 0.21
9.171 0.23 0.25 0.27 0.29 0.31 0.34 0.36
9.951 0.39 0.41 0.44 0.47 0.50 0.53 0.57
10.731 0.61 0.66 0.71 0.77 0.84 0.92 1.01
11.511 1.11 1.25 1.45 1.81 2.44 3.38 4.59
12.291 6.09 7.81 9.53 10.98 12.02 12.63 12.83
13.071 12.69 12.24 11.58 10.74 9.76 8.74 7.83
46
13.851 7.07 6.41 5.83 5.33 4.87 4.46 4.09
14.630 3.77 3.49 3.24 3.01 2.81 2.64 2.48
15.410 2.34 2.22 2.11 2.01 1.93 1.84 1.77
16.190 1.70 1.63 1.58 1.52 1.47 1.42 1.37
16.970 1.33 1.29 1.25 1.22 1.18 1.16 1.14
17.750 1.11 1.10 1.08 1.06 1.04 1.03 1.01
18.530 0.99 0.98 0.96 0.95 0.94 0.92 0.91
19.310 0.89 0.88 0.87 0.85 0.84 0.82 0.81
20.090 0.80 0.78 0.77 0.76 0.74 0.73 0.72
20.869 0.71 0.70 0.69 0.68 0.67 0.66 0.66
21.649 0.65 0.65 0.64 0.64 0.63 0.63 0.63
22.429 0.62 0.62 0.61 0.61 0.61 0.61 0.60
23.209 0.60 0.60 0.59 0.59 0.59 0.58 0.58
23.989 0.58 0.58 0.57 0.56 0.54 0.52 0.49
24.769 0.46 0.42 0.38 0.34 0.29 0.25 0.22
25.549 0.18 0.15 0.13 0.11 0.09 0.08 0.07
26.329 0.06
Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
Streets 0.030 1.729 12.92 12.02 401.19
Line
Start Time ------------ Flow Values @ time increment of 0.111 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
5.792 0.05 0.06 0.07 0.08 0.08 0.09 0.10
6.571 0.11 0.12 0.13 0.14 0.15 0.16 0.17
7.351 0.19 0.20 0.21 0.22 0.23 0.24 0.25
47
8.131 0.27 0.28 0.29 0.30 0.32 0.33 0.35
8.911 0.37 0.38 0.40 0.43 0.45 0.47 0.50
9.691 0.53 0.55 0.58 0.61 0.63 0.66 0.69
10.471 0.73 0.77 0.81 0.86 0.91 0.97 1.04
11.251 1.11 1.20 1.30 1.42 1.60 1.89 2.39
12.031 3.18 4.23 5.53 7.07 8.67 10.09 11.14
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Line
Start Time ------------ Flow Values @ time increment of 0.111 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
12.810 11.77 12.02 11.94 11.55 10.95 10.19 9.29
13.590 8.31 7.41 6.65 6.01 5.44 4.95 4.51
14.370 4.12 3.76 3.46 3.19 2.94 2.73 2.54
15.150 2.37 2.22 2.09 1.98 1.87 1.78 1.70
15.930 1.62 1.55 1.49 1.43 1.38 1.33 1.28
16.710 1.24 1.20 1.16 1.12 1.08 1.05 1.02
17.490 1.00 0.98 0.96 0.94 0.93 0.91 0.89
18.270 0.88 0.87 0.85 0.84 0.83 0.81 0.80
19.049 0.79 0.78 0.77 0.75 0.74 0.73 0.72
19.829 0.71 0.69 0.68 0.67 0.66 0.65 0.64
20.609 0.63 0.62 0.61 0.60 0.59 0.58 0.57
21.389 0.57 0.56 0.56 0.55 0.55 0.54 0.54
22.169 0.54 0.53 0.53 0.53 0.52 0.52 0.52
22.949 0.51 0.51 0.51 0.51 0.50 0.50 0.50
23.729 0.50 0.49 0.49 0.49 0.48 0.48 0.47
48
24.509 0.45 0.43 0.40 0.37 0.33 0.30 0.26
25.288 0.23 0.19 0.16 0.14 0.12 0.10 0.08
26.068 0.07 0.06 0.05
Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
Residential 0.113 0.515 12.98 11.80 104.65
Line
Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
11.858 0.16 0.53 1.20 2.15 3.44 5.06 6.86
12.575 8.53 9.89 10.88 11.50 11.80 11.76 11.49
13.292 11.01 10.32 9.51 8.74 8.08 7.49 6.97
14.009 6.51 6.09 5.69 5.33 5.01 4.72 4.46
14.726 4.22 4.00 3.81 3.63 3.48 3.34 3.21
15.443 3.10 3.00 2.90 2.81 2.73 2.65 2.58
16.160 2.51 2.45 2.38 2.32 2.26 2.20 2.14
16.877 2.09 2.04 2.00 1.97 1.93 1.90 1.87
17.594 1.84 1.82 1.79 1.77 1.75 1.73 1.71
18.311 1.68 1.66 1.64 1.62 1.60 1.59 1.57
19.029 1.55 1.53 1.51 1.49 1.47 1.45 1.43
19.746 1.41 1.39 1.37 1.35 1.33 1.31 1.29
20.463 1.27 1.26 1.24 1.22 1.21 1.19 1.18
21.180 1.17 1.16 1.15 1.14 1.13 1.12 1.12
21.897 1.11 1.10 1.10 1.09 1.09 1.08 1.08
22.614 1.08 1.07 1.07 1.06 1.06 1.06 1.05
23.331 1.05 1.05 1.04 1.04 1.03 1.03 1.03
49
24.048 1.02 1.01 1.00 0.98 0.95 0.90 0.85
24.765 0.78 0.71 0.63 0.55 0.48 0.41 0.35
25.482 0.30 0.25 0.21 0.18 0.15 0.13 0.11
26.199 0.09 0.08 0.07 0.06
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Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
Wetland 0.413 Upstream 0.453 12.98 37.52 90.95
Line
Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
5.916 0.06 0.07 0.08 0.08 0.09 0.10 0.11
6.633 0.12 0.13 0.14 0.15 0.16 0.17 0.18
7.350 0.19 0.20 0.23 0.27 0.29 0.31 0.33
8.067 0.35 0.37 0.39 0.42 0.44 0.46 0.49
8.784 0.52 0.55 0.58 0.61 0.65 0.69 0.73
9.501 0.77 0.82 0.86 0.91 0.96 1.00 1.05
10.219 1.11 1.16 1.22 1.29 1.36 1.44 1.53
10.936 1.63 1.74 1.86 2.00 2.16 2.34 2.55
11.653 2.84 3.29 4.17 5.69 8.02 11.11 15.04
12.370 19.65 24.54 29.05 32.70 35.32 36.89 37.52
50
13.087 37.26 36.28 34.72 32.64 30.19 27.70 25.41
13.804 23.40 21.64 20.08 18.68 17.40 16.24 15.19
14.521 14.24 13.39 12.62 11.92 11.30 10.73 10.23
15.238 9.78 9.37 9.00 8.67 8.37 8.09 7.84
15.955 7.60 7.37 7.16 6.96 6.77 6.59 6.42
16.672 6.26 6.10 5.95 5.81 5.68 5.56 5.45
17.389 5.35 5.26 5.18 5.11 5.04 4.97 4.91
18.107 4.85 4.79 4.73 4.68 4.62 4.57 4.51
18.824 4.46 4.40 4.35 4.30 4.25 4.19 4.14
19.541 4.09 4.03 3.98 3.93 3.87 3.82 3.77
20.258 3.71 3.66 3.61 3.55 3.50 3.46 3.41
20.975 3.37 3.34 3.30 3.27 3.24 3.22 3.19
21.692 3.17 3.15 3.14 3.12 3.10 3.09 3.08
22.409 3.06 3.05 3.04 3.03 3.02 3.01 2.99
23.126 2.98 2.97 2.96 2.95 2.94 2.93 2.92
23.843 2.91 2.90 2.89 2.87 2.83 2.78 2.70
24.560 2.59 2.45 2.28 2.09 1.89 1.68 1.49
25.278 1.30 1.12 0.96 0.82 0.70 0.60 0.51
25.995 0.44 0.38 0.32 0.28 0.21 0.14 0.10
Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
Wetland 0.413 Downstream 0.452 0.62 19.95 3.85 9.34
Line
Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
8.375 0.05 0.06 0.06 0.07 0.07 0.08 0.09
51
9.092 0.09 0.10 0.11 0.11 0.12 0.13 0.14
9.809 0.15 0.16 0.17 0.18 0.19 0.20 0.21
10.526 0.23 0.24 0.26 0.27 0.29 0.30 0.32
11.243 0.34 0.37 0.39 0.41 0.44 0.48 0.52
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Line
Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
11.960 0.57 0.65 0.76 0.92 1.12 1.38 1.70
12.677 2.07 2.47 2.89 3.31 3.72 3.73 3.74
13.394 3.75 3.75 3.76 3.77 3.78 3.78 3.79
14.111 3.79 3.80 3.80 3.80 3.81 3.81 3.81
14.828 3.82 3.82 3.82 3.82 3.82 3.83 3.83
15.546 3.83 3.83 3.83 3.83 3.83 3.84 3.84
16.263 3.84 3.84 3.84 3.84 3.84 3.84 3.84
16.980 3.84 3.84 3.84 3.85 3.85 3.85 3.85
17.697 3.85 3.85 3.85 3.85 3.85 3.85 3.85
18.414 3.85 3.85 3.85 3.85 3.85 3.85 3.85
19.131 3.85 3.85 3.85 3.85 3.85 3.85 3.85
19.848 3.85 3.85 3.85 3.85 3.85 3.85 3.85
20.565 3.85 3.85 3.85 3.85 3.85 3.85 3.85
21.282 3.85 3.85 3.85 3.85 3.85 3.85 3.85
21.999 3.85 3.85 3.85 3.85 3.85 3.85 3.85
22.716 3.85 3.85 3.85 3.85 3.85 3.85 3.85
23.434 3.84 3.84 3.84 3.84 3.84 3.84 3.84
52
24.151 3.84 3.84 3.84 3.84 3.84 3.84 3.84
24.868 3.84 3.84 3.84 3.84 3.84 3.84 3.84
25.585 3.84 3.83 3.83 3.83 3.83 3.83 3.83
26.302 3.83 3.83 3.83 3.82 3.82 3.82 3.82
27.019 3.82 3.82 3.82 3.82 3.82 3.81 3.81
27.736 3.81 3.81 3.81 3.81 3.81 3.81 3.80
28.453 3.80 3.80 3.80 3.80 3.80 3.80 3.80
29.170 3.80 3.79 3.79 3.79 3.79 3.79 3.79
29.887 3.79 3.79 3.78 3.78 3.78 3.78 3.78
30.605 3.78 3.78 3.78 3.77 3.77 3.77 3.77
31.322 3.77 3.77 3.77 3.77 3.77 3.76 3.76
32.039 3.76 3.76 3.76 3.76 3.76 3.76 3.75
32.756 3.75 3.75 3.75 3.75 3.75 3.75 3.75
33.473 3.75 3.74 3.74 3.74 3.74 3.74 3.74
34.190 3.74 3.74 3.73 3.73 3.73 3.73 3.73
34.907 3.73 3.73 3.73 3.73 3.72 3.72 3.72
35.624 3.72 3.72 3.72 3.72 3.72 3.70 3.65
36.341 3.61 3.56 3.52 3.47 3.43 3.39 3.34
37.058 3.30 3.26 3.22 3.18 3.14 3.10 3.06
37.775 3.02 2.99 2.95 2.91 2.88 2.84 2.80
38.493 2.77 2.73 2.70 2.67 2.63 2.60 2.57
39.210 2.54 2.50 2.47 2.44 2.41 2.38 2.35
39.927 2.32 2.29 2.26 2.24 2.21 2.18 2.15
40.644 2.13 2.10 2.07 2.05 2.02 2.00 1.97
41.361 1.95 1.92 1.90 1.88 1.85 1.83 1.81
42.078 1.78 1.76 1.74 1.72 1.70 1.67 1.65
42.795 1.63 1.61 1.59 1.57 1.55 1.53 1.51
43.512 1.50 1.48 1.46 1.44 1.42 1.40 1.39
44.229 1.37 1.35 1.33 1.32 1.30 1.29 1.27
44.946 1.25 1.24 1.22 1.21 1.19 1.18 1.16
45.663 1.15 1.13 1.12 1.11 1.09 1.08 1.06
53
46.381 1.05 1.04 1.03 1.01 1.00 0.99 0.97
47.098 0.96 0.95 0.94 0.93 0.92 0.90 0.89
47.815 0.88 0.87 0.86 0.85 0.84 0.83 0.82
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Line
Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
48.532 0.81 0.80 0.79 0.78 0.77 0.76 0.75
49.249 0.74 0.73 0.72 0.71 0.70 0.69 0.69
49.966 0.68 0.67 0.66 0.65 0.64 0.64 0.63
50.683 0.62 0.61 0.60 0.60 0.59 0.58 0.57
51.400 0.57 0.56 0.55 0.55 0.54 0.53 0.53
52.117 0.52 0.51 0.51 0.50 0.49 0.49 0.48
52.834 0.48 0.47 0.46 0.46 0.45 0.45 0.44
53.552 0.44 0.43 0.42 0.42 0.41 0.41 0.40
54.269 0.40 0.39 0.39 0.38 0.38 0.37 0.37
54.986 0.37 0.36 0.36 0.35 0.35 0.34 0.34
55.703 0.33 0.33 0.33 0.32 0.32 0.31 0.31
56.420 0.31 0.30 0.30 0.29 0.29 0.29 0.28
57.137 0.28 0.28 0.27 0.27 0.27 0.26 0.26
57.854 0.26 0.25 0.25 0.25 0.24 0.24 0.24
58.571 0.24 0.23 0.23 0.23 0.22 0.22 0.22
59.288 0.22 0.21 0.21 0.21 0.20 0.20 0.20
60.005 0.20 0.19 0.19 0.19 0.19 0.19 0.18
60.722 0.18 0.18 0.18 0.17 0.17 0.17 0.17
54
61.440 0.17 0.16 0.16 0.16 0.16 0.16 0.15
62.157 0.15 0.15 0.15 0.15 0.14 0.14 0.14
62.874 0.14 0.14 0.14 0.13 0.13 0.13 0.13
63.591 0.13 0.13 0.12 0.12 0.12 0.12 0.12
64.308 0.12 0.11 0.11 0.11 0.11 0.11 0.11
65.025 0.11 0.11 0.10 0.10 0.10 0.10 0.10
65.742 0.10 0.10 0.10 0.09 0.09 0.09 0.09
66.459 0.09 0.09 0.09 0.09 0.08 0.08 0.08
67.176 0.08 0.08 0.08 0.08 0.08 0.08 0.08
67.893 0.07 0.07 0.07 0.07 0.07 0.07 0.07
68.611 0.07 0.07 0.07 0.07 0.07 0.06 0.06
69.328 0.06 0.06 0.06 0.06 0.06 0.06 0.06
70.045 0.06 0.06 0.06 0.06 0.05 0.05 0.05
70.762 0.05 0.05 0.05 0.05 0.05
Area or Drainage Rain Gage Runoff ------------ Peak Flow ------------
Reach Area ID or Amount Elevation Time Rate Rate
Identifier (sq mi) Location (in) (ft) (hr) (cfs) (csm)
OUTLET 0.413 0.452 19.95 3.85 9.34
Line
Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
8.375 0.05 0.06 0.06 0.07 0.07 0.08 0.09
9.092 0.09 0.10 0.11 0.11 0.12 0.13 0.14
9.809 0.15 0.16 0.17 0.18 0.19 0.20 0.21
10.526 0.23 0.24 0.26 0.27 0.29 0.30 0.32
11.243 0.34 0.37 0.39 0.41 0.44 0.48 0.52
11.960 0.57 0.65 0.76 0.92 1.12 1.38 1.70
55
12.677 2.07 2.47 2.89 3.31 3.72 3.73 3.74
13.394 3.75 3.75 3.76 3.77 3.78 3.78 3.79
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Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
14.111 3.79 3.80 3.80 3.80 3.81 3.81 3.81
14.828 3.82 3.82 3.82 3.82 3.82 3.83 3.83
15.546 3.83 3.83 3.83 3.83 3.83 3.84 3.84
16.263 3.84 3.84 3.84 3.84 3.84 3.84 3.84
16.980 3.84 3.84 3.84 3.85 3.85 3.85 3.85
17.697 3.85 3.85 3.85 3.85 3.85 3.85 3.85
18.414 3.85 3.85 3.85 3.85 3.85 3.85 3.85
19.131 3.85 3.85 3.85 3.85 3.85 3.85 3.85
19.848 3.85 3.85 3.85 3.85 3.85 3.85 3.85
20.565 3.85 3.85 3.85 3.85 3.85 3.85 3.85
21.282 3.85 3.85 3.85 3.85 3.85 3.85 3.85
21.999 3.85 3.85 3.85 3.85 3.85 3.85 3.85
22.716 3.85 3.85 3.85 3.85 3.85 3.85 3.85
23.434 3.84 3.84 3.84 3.84 3.84 3.84 3.84
24.151 3.84 3.84 3.84 3.84 3.84 3.84 3.84
24.868 3.84 3.84 3.84 3.84 3.84 3.84 3.84
25.585 3.84 3.83 3.83 3.83 3.83 3.83 3.83
26.302 3.83 3.83 3.83 3.82 3.82 3.82 3.82
27.019 3.82 3.82 3.82 3.82 3.82 3.81 3.81
56
27.736 3.81 3.81 3.81 3.81 3.81 3.81 3.80
28.453 3.80 3.80 3.80 3.80 3.80 3.80 3.80
29.170 3.80 3.79 3.79 3.79 3.79 3.79 3.79
29.887 3.79 3.79 3.78 3.78 3.78 3.78 3.78
30.605 3.78 3.78 3.78 3.77 3.77 3.77 3.77
31.322 3.77 3.77 3.77 3.77 3.77 3.76 3.76
32.039 3.76 3.76 3.76 3.76 3.76 3.76 3.75
32.756 3.75 3.75 3.75 3.75 3.75 3.75 3.75
33.473 3.75 3.74 3.74 3.74 3.74 3.74 3.74
34.190 3.74 3.74 3.73 3.73 3.73 3.73 3.73
34.907 3.73 3.73 3.73 3.73 3.72 3.72 3.72
35.624 3.72 3.72 3.72 3.72 3.72 3.70 3.65
36.341 3.61 3.56 3.52 3.47 3.43 3.39 3.34
37.058 3.30 3.26 3.22 3.18 3.14 3.10 3.06
37.775 3.02 2.99 2.95 2.91 2.88 2.84 2.80
38.493 2.77 2.73 2.70 2.67 2.63 2.60 2.57
39.210 2.54 2.50 2.47 2.44 2.41 2.38 2.35
39.927 2.32 2.29 2.26 2.24 2.21 2.18 2.15
40.644 2.13 2.10 2.07 2.05 2.02 2.00 1.97
41.361 1.95 1.92 1.90 1.88 1.85 1.83 1.81
42.078 1.78 1.76 1.74 1.72 1.70 1.67 1.65
42.795 1.63 1.61 1.59 1.57 1.55 1.53 1.51
43.512 1.50 1.48 1.46 1.44 1.42 1.40 1.39
44.229 1.37 1.35 1.33 1.32 1.30 1.29 1.27
44.946 1.25 1.24 1.22 1.21 1.19 1.18 1.16
45.663 1.15 1.13 1.12 1.11 1.09 1.08 1.06
46.381 1.05 1.04 1.03 1.01 1.00 0.99 0.97
47.098 0.96 0.95 0.94 0.93 0.92 0.90 0.89
47.815 0.88 0.87 0.86 0.85 0.84 0.83 0.82
48.532 0.81 0.80 0.79 0.78 0.77 0.76 0.75
49.249 0.74 0.73 0.72 0.71 0.70 0.69 0.69
57
49.966 0.68 0.67 0.66 0.65 0.64 0.64 0.63
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Second possible alternative
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Start Time ------------ Flow Values @ time increment of 0.102 hr ------------
(hr) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs)
50.683 0.62 0.61 0.60 0.60 0.59 0.58 0.57
51.400 0.57 0.56 0.55 0.55 0.54 0.53 0.53
52.117 0.52 0.51 0.51 0.50 0.49 0.49 0.48
52.834 0.48 0.47 0.46 0.46 0.45 0.45 0.44
53.552 0.44 0.43 0.42 0.42 0.41 0.41 0.40
54.269 0.40 0.39 0.39 0.38 0.38 0.37 0.37
54.986 0.37 0.36 0.36 0.35 0.35 0.34 0.34
55.703 0.33 0.33 0.33 0.32 0.32 0.31 0.31
56.420 0.31 0.30 0.30 0.29 0.29 0.29 0.28
57.137 0.28 0.28 0.27 0.27 0.27 0.26 0.26
57.854 0.26 0.25 0.25 0.25 0.24 0.24 0.24
58.571 0.24 0.23 0.23 0.23 0.22 0.22 0.22
59.288 0.22 0.21 0.21 0.21 0.20 0.20 0.20
60.005 0.20 0.19 0.19 0.19 0.19 0.19 0.18
60.722 0.18 0.18 0.18 0.17 0.17 0.17 0.17
61.440 0.17 0.16 0.16 0.16 0.16 0.16 0.15
62.157 0.15 0.15 0.15 0.15 0.14 0.14 0.14
62.874 0.14 0.14 0.14 0.13 0.13 0.13 0.13
63.591 0.13 0.13 0.12 0.12 0.12 0.12 0.12
64.308 0.12 0.11 0.11 0.11 0.11 0.11 0.11
58
65.025 0.11 0.11 0.10 0.10 0.10 0.10 0.10
65.742 0.10 0.10 0.10 0.09 0.09 0.09 0.09
66.459 0.09 0.09 0.09 0.09 0.08 0.08 0.08
67.176 0.08 0.08 0.08 0.08 0.08 0.08 0.08
67.893 0.07 0.07 0.07 0.07 0.07 0.07 0.07
68.611 0.07 0.07 0.07 0.07 0.07 0.06 0.06
69.328 0.06 0.06 0.06 0.06 0.06 0.06 0.06
70.045 0.06 0.06 0.06 0.06 0.05 0.05 0.05
70.762 0.05 0.05 0.05 0.05 0.05
59