MARC BMP Manual Training Module 2

2008-2009 Training Presentation

1. A
BMP Training Module 2BMP Training Module 2
Extended Wet Detention Basin Extended Wet Detention Basin
& Extended Detention Wetlands& Extended Detention Wetlands
Sponsored by: MARCSponsored by: MARC
Presenters: Presenters:
Andy Sauer, P.E. (CDM)Andy Sauer, P.E. (CDM)
Natalie Postel, P.E. (CDM)Natalie Postel, P.E. (CDM)

December 12, 2008

2. A
AgendaAgenda
8:30-9:20 Lecture 1: Overview of Extended Detention and Wetlands8:30-9:20 Lecture 1: Overview of Extended Detention and Wetlands

Review Module 1 and WQv definitionReview Module 1 and WQv definition

Define “Extended Detention”Define “Extended Detention”

Define Extended Wet Detention and Extended Detention WetlandsDefine Extended Wet Detention and Extended Detention Wetlands
10 minute break10 minute break
9:30-10:30 Lecture 2: Design Examples9:30-10:30 Lecture 2: Design Examples

Extended Wet Detention BasinExtended Wet Detention Basin

Extended Detention WetlandExtended Detention Wetland
15 minute break15 minute break
10:45 – 11:30 Design Activity10:45 – 11:30 Design Activity
11:30 – 11:45 Design Activity Results11:30 – 11:45 Design Activity Results
11:45 – 12:00 Lecture 3: Other considerations11:45 – 12:00 Lecture 3: Other considerations

ImplementationImplementation

Operations and maintenanceOperations and maintenance

VegetationVegetation

Lessons learned Lessons learned

3. A
Best Management Practice Best Management Practice
(BMP)(BMP)
BestBest – State of the Practice – State of the Practice

No definitive answerNo definitive answer

Past experience, testing, research, Past experience, testing, research,

Unique to siteUnique to site
ManagementManagement – Responsible Parties – Responsible Parties

Improve water quality, meet NPDES Phase IIImprove water quality, meet NPDES Phase II

Jurisdictional specificJurisdictional specific

Meet specific requirements of a regionalMeet specific requirements of a regional
PracticePractice – Action or Implementation – Action or Implementation

Practice = defined to carry out, apply, or to Practice = defined to carry out, apply, or to
do or perform often. do or perform often.

4. A
Basic BMP PrinciplesBasic BMP Principles
PlanPlan for stormwater management for stormwater management

Sustainable and “be green”Sustainable and “be green”

Provide a level of serviceProvide a level of service

Improve water qualityImprove water quality
MimicMimic natural hydrology natural hydrology

Increase initial abstraction Increase initial abstraction

Promote infiltration, retention & ETPromote infiltration, retention & ET
““Treat”Treat” the stormwater runoff the stormwater runoff

Natural processesNatural processes

Treatment trainsTreatment trains

5. A
BMP Evaluation ProcessBMP Evaluation Process
Extended detention
(40 hours) to
increase treatment
and decrease peak
flows
PLAN
MIMIC
TREAT

6. A
Detention and TreatmentDetention and Treatment
Structural BMPs Structural BMPs
detain runoffdetain runoff

Extended Detention Extended Detention
BasinsBasins
•WetWet
•DryDry

Extended Detention Extended Detention
WetlandsWetlands

Infiltration basinsInfiltration basins
Typically used as Typically used as
larger, centralized larger, centralized
facilitiesfacilities
Topeka KS
TREAT

7. A
Example siteExample site
M
ain C
hannel
B
r
i
d
g
e
Streambank
Biostabilization
Culvert
R
o
ad
w
ay
Grass Swale
Wet
Pond
Commercial
Building
Bio-
Filters
Design Documents
– APWA 5600
– BMP Manual
– Watershed
Master Plans
TREAT

8. A
Structural BMP ConsiderationStructural BMP Consideration
Pollutant removal efficiencyPollutant removal efficiency
Water quality volumeWater quality volume
Site suitabilitySite suitability
Tributary areaTributary area
Dimensions (depth, length-width ratio)Dimensions (depth, length-width ratio)
OutletOutlet
Emergency spillwayEmergency spillway
Maintenance easementMaintenance easement
Routine and non-routine maintenanceRoutine and non-routine maintenance

9. A
BMP EvaluationBMP Evaluation
General RuleGeneral Rule
W
a
te
r Q
u
a
lity
W
a
t
e
r

Q
u
a
n
t
i
t
y
Aesthetics/Amenity

10. A
BMP ManualBMP Manual

11. A
Post Development BMP Post Development BMP
SelectionSelection

12. A
BMP Selection FlowchartBMP Selection Flowchart
Level Of Service
BMP Value Rating
Water Quality
Volume/sizing
Placement,
maintenance

13. A
Water Quality Volume (WQv)Water Quality Volume (WQv)
Water Quality Volume Water Quality Volume
(WQv): The storage needed (WQv): The storage needed
to capture and treat 90% of to capture and treat 90% of
the average annual storm the average annual storm
runoff volumerunoff volume
Water Quality Storm: The Water Quality Storm: The
storm event that produces storm event that produces ≤ ≤
90% volume of all daily 90% volume of all daily
storms in a year storms in a year
Extended detention and Extended detention and
wetlands sizing is based on wetlands sizing is based on
the WQvthe WQv
WQv

14. A
2003 Kansas City Precip events
0
5
10
15
20
25
30
35
40
45
0
. 1
0
. 3
0
. 5
0
. 7
0
. 9
1
. 1
1
. 3
1
. 5
1
. 7
1
. 9
2
. 1
2
. 3
2
. 5
2
. 7
Daily Precipitation (in)
#

o
f

d
a
y
s

>

o
r
=
Kansas City Water Quality Kansas City Water Quality
StormStorm
Water Quality
Storm = 1.37 in
Young and McEnroe
(http://kcmetro.apwa.net)

15. A
Why Use the WQv to size Why Use the WQv to size
BMP?BMP?
Retain runoff long enough to get Retain runoff long enough to get
water quality benefits water quality benefits
Reducing erosive flows from Reducing erosive flows from
smaller runoff eventssmaller runoff events

16. A
Water Quality Volume Water Quality Volume
CalculationCalculation
Two methodsTwo methods

Short-Cut MethodShort-Cut Method
•Sites < 10 acresSites < 10 acres
•Only 1 predominant cover typeOnly 1 predominant cover type

Small Storm Hydrology MethodSmall Storm Hydrology Method
•Larger or more heterogeneous drainage Larger or more heterogeneous drainage
areasareas

17. A
WQv CalculationWQv Calculation
Short-Cut MethodShort-Cut Method
WQv = P*RvWQv = P*Rv

P = 24 hour Water Quality Storm (inches)P = 24 hour Water Quality Storm (inches)

Rv = Volumetric run coefficient = Rv = Volumetric run coefficient =
0.05+0.009(I)0.05+0.009(I)

I = % site Imperviousness I = % site Imperviousness

18. A
WQv CalculationWQv Calculation
Small Storm Hydrology MethodSmall Storm Hydrology Method
WQv = P*Weighted RvWQv = P*Weighted Rv
Weighted Rv = Weighted Rv = ΣΣ(Rv(Rv
ii*Ac*Ac
ii)/Total area (ac))/Total area (ac)
RvRv
ii = Volumetric runoff coefficient for cover = Volumetric runoff coefficient for cover
type (table)type (table)
AcAc
ii = Area of cover type i (ac) = Area of cover type i (ac)

19. A
Questions?Questions?

20. A
Why the term “Extended” Why the term “Extended”
Detention?Detention?
Extended: Designed to release the WQv over a period Extended: Designed to release the WQv over a period
of 40 hours of 40 hours
Allows time for more particles and associated Allows time for more particles and associated
pollutants to settle outpollutants to settle out
Reduces the downstream velocity and erosive Reduces the downstream velocity and erosive
conditionsconditions
More closely imitates natural release rates and More closely imitates natural release rates and
durationduration

21. A
Geomorphic Effects of Geomorphic Effects of
Uncontrolled Urban RunoffUncontrolled Urban Runoff

22. A
0.1
1
10
100
1000
z G q· B Ú y·
Flow Frequency for Flow Frequency for
DetentionDetention
7-yr
2/yr
20/yr
Storm Return Interval
more frequent than 1-yr

1-yr 10-yr 100-yr2-yr
Undeveloped
Developed
Uncontrolled
6/yr







F
l
o
w

23. A
40-Hour Drawdown Impacts40-Hour Drawdown Impacts
Storm Return Interval
more frequent than 1-yr

1-yr 10-yr 100-yr2-yr







F
l
o
w




Undeveloped
Developed
Uncontrolled
Developed
Controlled
0.80 psf
0.26 psf
0.1
1
10
100
1000
0.01 0.1 1 10 100
•10-year control
•1-year control
•WQv – extended
detention with 40 hr
drawdown

24. A
BMP ManualBMP Manual
Extended DetentionExtended Detention
Water Quality (40-hr)Water Quality (40-hr)

Pollutant removal throughPollutant removal through
•SettlingSettling
•Biological uptake (more for Biological uptake (more for
wetland)wetland)
•Permanent PoolPermanent Pool
•WQv = Volume above the WQv = Volume above the
permanent poolpermanent pool
Stream Sustainability (40-hr)Stream Sustainability (40-hr)

Mimic undeveloped Mimic undeveloped
conditions for full range of conditions for full range of
hydrologyhydrology

Can meet flood control Can meet flood control
objectivesobjectives

25. A
Extended Wet Detention Basin (EWDB)Extended Wet Detention Basin (EWDB)

26. A
EWDB Littoral BenchEWDB Littoral Bench
Littoral
Bench

27. A
EWDB Littoral BenchEWDB Littoral Bench
Provides water quality Provides water quality
treatmenttreatment
Mild slope serves as Mild slope serves as
safety feature around safety feature around
perimeter of permanent perimeter of permanent
pool pool
25% to 50% of 25% to 50% of
permanent pool surface permanent pool surface
areaarea
Helps control geese Helps control geese
accessaccess
Topeka, KS

28. A
EWDB Permanent PoolEWDB Permanent Pool

29. A
EWDB Permanent PoolEWDB Permanent Pool
Water quality volume Water quality volume
(WQv) mixes with (WQv) mixes with
permanent poolpermanent pool
WQv released over 40 WQv released over 40
hourshours
Minimum depth of 6-ftMinimum depth of 6-ft
Residence time of 14 Residence time of 14
daysdays
Significantly more Significantly more
water quality benefit water quality benefit
than EDDBthan EDDB
Topeka, KS

30. A
EWDB Outlet StructureEWDB Outlet Structure
Release the WQv over a period of Release the WQv over a period of
40 hours40 hours
Protected by well screens, trash Protected by well screens, trash
racks or gratesracks or grates
Located as far from inlet as Located as far from inlet as
possiblepossible
Various outlet structure optionsVarious outlet structure options

Single OrificeSingle Orifice

Perforated Riser or PlatePerforated Riser or Plate

V-notch Weir V-notch Weir
Source: Hubbard Brook LTER

31. A
Extended Detention

32. A
EWDB VegetationEWDB Vegetation
Upland area: Native Upland area: Native
grasses (preferable) or grasses (preferable) or
turf on berms and side turf on berms and side
slopesslopes
Littoral Zone: Native Littoral Zone: Native
wetland species wetland species
Recommend 3-5 native Recommend 3-5 native
speciesspecies
Soft Rush, Juncus effusus
Kansas City, MO

33. A
EWDB Siting ConsiderationsEWDB Siting Considerations
Off-line, outside of stream corridorOff-line, outside of stream corridor
EWDBs can be located within larger flood EWDBs can be located within larger flood
control facilitiescontrol facilities
Minimum 20 feet setbackMinimum 20 feet setback
Not on fill sites or steep slopes (unless Not on fill sites or steep slopes (unless
enhanced)enhanced)
Use fences and landscaping to impede access Use fences and landscaping to impede access
areas to address public safety concernsareas to address public safety concerns

Outflow structure shall be fencedOutflow structure shall be fenced

34. A
Questions on Extended Wet Questions on Extended Wet
Detention Basin (EWDB)?Detention Basin (EWDB)?

35. A
Extended Detention Wetland (EDW)Extended Detention Wetland (EDW)

36. A
EWD Permanent PoolEWD Permanent Pool
Permanent pool extends throughout wetlandPermanent pool extends throughout wetland

37. A
Extended Detention Wetland Extended Detention Wetland
(EDW)(EDW)
Forebay

38. A
EDW ForebayEDW Forebay
Same function as Same function as
EWDB EWDB
Should hold at least Should hold at least
10% of the WQv10% of the WQv
Separated from the Separated from the
wetland by a earth wetland by a earth
weir, gabion or loose weir, gabion or loose
riprap wallriprap wall
Topeka, KS

39. A
EDW MarshEDW Marsh
Marsh
Pollutant removal through plant root systemsPollutant removal through plant root systems
Shallower than EWDB permanent poolShallower than EWDB permanent pool

40. A
EDW MicropoolEDW Micropool
Micropool
Reverse slope pipe under the surface of the micropool is
used to prevent clogging

41. A
EDW MicropoolEDW Micropool
Prevents outlet clogging Prevents outlet clogging
Allows further settling of Allows further settling of
sedimentsediment
Should have a capacity of Should have a capacity of
at least 10% of WQvat least 10% of WQv
Surrounded with a safety Surrounded with a safety
bench bench

42. A
EDW Outlet Structure, Outfall, EDW Outlet Structure, Outfall,
and Emergency Spillwayand Emergency Spillway

43. A
EDW VegetationEDW Vegetation
Vegetation should cover 50-75% of surface areaVegetation should cover 50-75% of surface area
3-5 native species are recommended3-5 native species are recommended
Select species based on stress tolerance and ability Select species based on stress tolerance and ability
to handle variations in water availabilityto handle variations in water availability
Consult local expertsConsult local experts
Topeka, KS
Lenexa, KS
Topeka, KS

44. A
EDW Siting ConsiderationsEDW Siting Considerations
Off-line, outside of stream corridorOff-line, outside of stream corridor
Perform water budget analysis to ensure Perform water budget analysis to ensure
permanent poolpermanent pool
Soils should be suited for wetland speciesSoils should be suited for wetland species

Hydric soils with high phosphorous affinityHydric soils with high phosphorous affinity
Not on fill sites or steep slopes (unless Not on fill sites or steep slopes (unless
enhanced)enhanced)
Use fences and landscaping to impede Use fences and landscaping to impede
access areas of public safety concernaccess areas of public safety concern

Outflow structure shall be fencedOutflow structure shall be fenced

45. A
Extended Wet DetentionExtended Wet Detention
versusversus
Extended Detention WetlandsExtended Detention Wetlands
SimilaritiesSimilarities

Water quality volume mixes with Water quality volume mixes with
permanent poolpermanent pool

40 hour drawdown of water quality 40 hour drawdown of water quality
volume (WQvolume (WQ
vv))
Differences Differences

Depth of permanent pool (18 inches in Depth of permanent pool (18 inches in
wetland vs. 6 to 12 feet in basin)wetland vs. 6 to 12 feet in basin)

Vegetation types and planting Vegetation types and planting
configurationsconfigurations

46. A
AdvantagesAdvantages
andand
DisadvantagesDisadvantages

47. A
EWDB AdvantagesEWDB Advantages
Settling of suspended Settling of suspended
solids solids
Pollutant uptake by pond Pollutant uptake by pond
vegetationvegetation
Flood control via peak Flood control via peak
discharge attenuationdischarge attenuation
Control of channel erosion Control of channel erosion
by reducing downstream by reducing downstream
flow velocitiesflow velocities
Creation of wildlife habitatCreation of wildlife habitat
Recreational and aesthetic Recreational and aesthetic
benefitsbenefits
Topeka, KS

48. A
EDW AdvantagesEDW Advantages
Settling of suspended solids Settling of suspended solids
Pollutant uptake by wetland Pollutant uptake by wetland
vegetationvegetation
Flood control via peak Flood control via peak
discharge attenuationdischarge attenuation
Control of channel erosion Control of channel erosion
by reducing downstream by reducing downstream
flow velocitiesflow velocities
Creation of wildlife and Creation of wildlife and
aquatic habitatsaquatic habitats
Recreational and aesthetic Recreational and aesthetic
benefitsbenefits
Some groundwater rechargeSome groundwater recharge

49. A
EWDB DisadvantagesEWDB Disadvantages
Potential safety concerns Potential safety concerns
Additional maintenance due to Additional maintenance due to
sediment removal, floating sediment removal, floating
trash, scum, and algal bloomstrash, scum, and algal blooms
Potential odor problemsPotential odor problems
Need conditions to sustain Need conditions to sustain
permanent poolpermanent pool
Resident waterfowl can Resident waterfowl can
become a source of fecal become a source of fecal
coliform and nutrientscoliform and nutrients
Vector issues may result in Vector issues may result in
additional maintenance additional maintenance
requirementsrequirements

50. A
EDW DisadvantagesEDW Disadvantages
Require more space, due Require more space, due
to shallower depth of to shallower depth of
water storage water storage
Additional maintenance Additional maintenance
due to vegetation due to vegetation
overgrowthovergrowth
Requires larger drainage Requires larger drainage
area to sustain permanent area to sustain permanent
poolpool
Vector issues can result in Vector issues can result in
increased maintenance increased maintenance
requirementsrequirements
Site limitations in urban Site limitations in urban
areasareas

51. A
Break 10 minuteBreak 10 minute
Questions?Questions?

52. A
Lecture 2Lecture 2
Design of EWDB & EDWDesign of EWDB & EDW
Discuss key design featuresDiscuss key design features
Introduce calculations for each major Introduce calculations for each major
componentcomponent
Perform example calculationsPerform example calculations

53. A
Extended Wet Detention BasinExtended Wet Detention Basin
Key Design FeaturesKey Design Features
Water quality storage volumeWater quality storage volume
Permanent poolPermanent pool
Outlet structuresOutlet structures

OrificeOrifice

Perforated riser or plate Perforated riser or plate

V-notch weirV-notch weir
Pool shapePool shape
Basin shapeBasin shape
ForebayForebay
Littoral benchLittoral bench
VegetationVegetation
Topeka, KS

54. A
Design ExampleDesign Example
26 acre drainage 26 acre drainage
Land useLand use

1.6 acres of flat 1.6 acres of flat
roofsroofs

8.8 acres of parking 8.8 acres of parking
lotlot

3.3 acres of narrow 3.3 acres of narrow
streetsstreets

12.3 acres of silty 12.3 acres of silty
soilsoil

53 % impervious53 % impervious
Outlet Structure Outlet Structure
designed for 40 hour designed for 40 hour
release of WQvrelease of WQv
New Development Site

55. A
Water Quality Storage VolumeWater Quality Storage Volume
i.i.Tributary area = 26 acresTributary area = 26 acres
ii.ii.Calculate water quality storage volumeCalculate water quality storage volume
EWDB Design Procedure Form

56. A
Water Quality Storage VolumeWater Quality Storage Volume
ii.ii.Calculate Water Quality Storage Calculate Water Quality Storage
Volume (WQv)Volume (WQv)
Two methodsTwo methods

Short-Cut MethodShort-Cut Method
•Sites < 10 acresSites < 10 acres
•Only 1 predominant cover typeOnly 1 predominant cover type

Small Storm Hydrology MethodSmall Storm Hydrology Method
•Larger or more heterogeneous Larger or more heterogeneous
drainage areasdrainage areas

57. A
Water Quality Storage VolumeWater Quality Storage Volume
Short-Cut MethodShort-Cut Method
WQv = P*RvWQv = P*Rv

P = 24 hour Water Quality Storm (inches)P = 24 hour Water Quality Storm (inches)
P = 1.37 inches (Kansas City)P = 1.37 inches (Kansas City)

Rv = Volumetric run coefficient = 0.05+0.009(I)Rv = Volumetric run coefficient = 0.05+0.009(I)

I = % site imperviousness I = % site imperviousness

58. A
Water Quality Storage VolumeWater Quality Storage Volume
Small Storm Hydrology MethodSmall Storm Hydrology Method
WQv = (P)*(Weighted Rv)WQv = (P)*(Weighted Rv)
Weighted Rv = Weighted Rv = ΣΣ(Rv(Rv
ii*Ac*Ac
ii)/Total area (ac))/Total area (ac)
•RvRv
ii = Volumetric runoff coefficient for cover type = Volumetric runoff coefficient for cover type
(table)(table)
•AcAc
ii = Area of cover type i (ac) = Area of cover type i (ac)

59. A
Rv TableRv Table
TABLE 7
VOLUMETRIC COEFFICIENTS FOR URBAN RUNOFF FOR
DIRECTLY CONNECTED IMPERVIOUS AREAS
(CLAYTOR AND SCHUELER 1996)
Rainfall Rainfall
(inches)(inches)
Flat roofs and Flat roofs and
large unpaved large unpaved
parking lotsparking lots
Pitched roofs and Pitched roofs and
large impervious large impervious
areas areas
(large parking lots)(large parking lots)
Small Small
impervious impervious
areas and areas and
narrow narrow
streetsstreets
Silty Silty
soils soils
HSG-BHSG-B
Clayey soils Clayey soils
HSG-C and HSG-C and
DD
0.750.75 0.820.82 0.970.97 0.660.66 0.110.11 0.200.20
1.001.00 0.840.84 0.970.97 0.700.70 0.110.11 0.210.21
1.251.25 0.860.86 0.980.98 0.740.74 0.130.13 0.220.22
1.371.37 0.870.87 0.980.98 0.750.75 0.140.14 0.230.23
1.501.50 0.880.88 0.990.99 0.770.77 0.150.15 0.240.24
Note: a reduction factor may be applied to the Rv values for disconnected
surfaces, consult the BMP hydrology section

60. A
Water Quality Control Volume Water Quality Control Volume
Cover TypeCover Type RvRv Area (acres)Area (acres)
Flat roofsFlat roofs 0.870.87 1.61.6
Parking lotsParking lots 0.980.98 8.88.8
Narrow streetsNarrow streets 0.750.75 3.33.3
Silty soilSilty soil 0.140.14 12.312.3
( )
å
å
=´
´+´+´+´
=´
´
= inP
AreaTotal
AcRv
WQv
ii
749.037.1
26
3.1214.3.375.8.898.6.187.

61. A
Water Quality Storage VolumeWater Quality Storage Volume
Convert WQv from inches to ac-ft by converting Convert WQv from inches to ac-ft by converting
inches to feet and multiplying by the tributary inches to feet and multiplying by the tributary
areaarea
= (0.749in)*(1ft/12in)*26ac

62. A
Permanent PoolPermanent Pool
Permanent Pool

63. A
Permanent PoolPermanent Pool
Average pool depth 4 to Average pool depth 4 to
6 feet (not to exceed 6 feet (not to exceed
12 feet)12 feet)
A portion of the pool A portion of the pool
must be at least 10 feet must be at least 10 feet
if the pool is to contain if the pool is to contain
fish fish
At least 5.5 acres of At least 5.5 acres of
tributary area per ac-ft tributary area per ac-ft
of permanent poolof permanent pool
At least 10.3 acres of At least 10.3 acres of
tributary area per acre tributary area per acre
of pool surface areaof pool surface area
14 day residence time14 day residence time

64. A
Permanent Pool Volume (PPermanent Pool Volume (P
vv))
Method 1Method 1
Based on the time required for algae to uptake Based on the time required for algae to uptake
sufficient phosphoroussufficient phosphorous
VV
P1P1 = (C * A = (C * A
TT * R * R
1414) / 12) / 12

C = Runoff coefficient = 0.3 +0.6*I or APWA C = Runoff coefficient = 0.3 +0.6*I or APWA
section 5602.3 section 5602.3

I = Fraction of impervious area I = Fraction of impervious area
RR
1414 = 14-day wet season rainfall = 14-day wet season rainfall
AA
tt = total tributary acreage = total tributary acreage

65. A
Permanent Pool Volume (PPermanent Pool Volume (P
vv))
Method 2Method 2
Based on the time required for suspended Based on the time required for suspended
solids to settlesolids to settle
VV
P2P2 = (V = (V
BB/V/V
RR * S * S
DD * A * A
ii) / 12) / 12
VV
BB/V/V
RR = ratio of design water quality volume = ratio of design water quality volume
to runoff volume (should be at least 4 for to runoff volume (should be at least 4 for
adequate TSS removal)adequate TSS removal)
SS
DD = mean storm depth = mean storm depth
AA
ii = impervious tributary acreage = impervious tributary acreage

66. A
Permanent Pool Volume (PPermanent Pool Volume (P
vv))
Method 1Method 1
Kansas City
From APWA section 5602.3
= (0.6*26*2.2)/12
= 0.3+0.6*.53

67. A
Permanent Pool Volume (PPermanent Pool Volume (P
vv))
Method 2Method 2
~93%
V
B/R
=5
Figure 24

68. A
Permanent Pool Volume (PPermanent Pool Volume (P
vv))
Method 2Method 2
= (5.0*0.6*13.7)/12
Kansas City
5.0
0.6
13.7
3.43
Correction: Step 1 should refer to Figure 24

69. A
Permanent Pool Volume (PPermanent Pool Volume (P
vv))
1.1.Use the larger volume calculated in the Use the larger volume calculated in the
previous steps and add 20% for sedimentationprevious steps and add 20% for sedimentation
2.2.Average pool depth: 4 to 6ftAverage pool depth: 4 to 6ft
3.3.Surface area = VSurface area = V
PP / Z / Z
PP
= 3.43*1.20

70. A
Outlet StructureOutlet Structure
V-notch Weir
Single Orifice
Perforated Riser or Plate

71. A
Outlet StructureOutlet Structure
Outlet sized to release Outlet sized to release
WQWQ
vv (ac-ft) within 40 (ac-ft) within 40
hourshours
Locate outlet as far Locate outlet as far
away from inlet as away from inlet as
possiblepossible

Avoid short-circuitingAvoid short-circuiting
The facility must The facility must
bypass 1% storm eventbypass 1% storm event
Provide at least 1ft of Provide at least 1ft of
freeboard above WQfreeboard above WQ
VV
stage stage

72. A
Single Orifice OutletSingle Orifice Outlet

73. A
Single Orifice OutletSingle Orifice Outlet
i.i.Depth of water quality volume at outlet (ZDepth of water quality volume at outlet (Z
WQWQ))
ZZ
WQWQ = 3 feet = 3 feet
ii.ii.Average head of WQv over invert of orifice, Average head of WQv over invert of orifice,
HH
WQ WQ (ft)(ft)
HH
WQWQ = 0.5*Z = 0.5*Z
WQWQ
iii.iii.Average water quality outflow rate, QAverage water quality outflow rate, Q
WQWQ (cfs) (cfs)
QQ
WQWQ = (WQ = (WQ
VV * 43,560) / (40 * 3,600) * 43,560) / (40 * 3,600)

74. A
Single Orifice OutletSingle Orifice Outlet
= 0.5*3.0ft
= (1.62*43,560)/(40*3600)

75. A
Single Orifice OutletSingle Orifice Outlet
iv.Set orifice coefficient
(Co) depending on
orifice plate thickness
uD
o
must be greater than
4 inches in the following
step
uC
0
= 0.66 if plate
thickness is < D
o
uC
0
= 0.80 if > D
o

76. A
Single Orifice Outlet Single Orifice Outlet
v.v.Orifice diameter (DOrifice diameter (D
oo) must be greater than 4 ) must be greater than 4
inches, otherwise use weir or riserinches, otherwise use weir or riser
( )WQoWQo H * g * 2 * * C / Q * 2 * 12 D p=
g=32.2 ft/sec
2
π = 3.14

77. A
Single Orifice OutletSingle Orifice Outlet
D
o
=12*2*(0.49/(0.66*π*(2*32.2*1.5)
0.5
))
0.5

78. A
Perforated Riser or Plate Perforated Riser or Plate
OutletOutlet
Photo taken by Larry Roesner
Photo taken by Larry Roesner

79. A
Perforated Riser or Plate Perforated Riser or Plate
OutletOutlet

80. A
Perforated Riser or Plate Perforated Riser or Plate
OutletOutlet
Calculate outlet area per row of Calculate outlet area per row of
perforations (Aperforations (A
oo))
AA
oo (in (in
22
) = WQ) = WQ
vv / (0.013 * Z / (0.013 * Z
WQWQ
22
+ 0.22 * Z + 0.22 * Z
WQWQ – 0.1) – 0.1)
Assuming a single column, calculate Assuming a single column, calculate
the diameter of a single perforation for the diameter of a single perforation for
each roweach row
DD
11 = (4 * A = (4 * A
oo / / π)π)
1/21/2

If DIf D
11 is greater than 2 inches add more is greater than 2 inches add more
columnscolumns n
c
= 4

81. A
Perforated Riser or Plate Perforated Riser or Plate
OutletOutlet
= 1.62/(0.013*3.0
2
+0.22*3.0–0.1)
= (4*2.4/π)
1/2
3.0
2.4
1.75
1
1.75
NA
9

82. A
Perforated Riser or Plate Perforated Riser or Plate
OutletOutlet
Use number of columns to determine exact Use number of columns to determine exact
perforation diameterperforation diameter
DD
perfperf = (4 / = (4 / ππ * A * A
oo / n / n
cc))
1/21/2
Using a 4” center to center vertical spacing Using a 4” center to center vertical spacing
and Zand Z
WQWQ, determine number of rows (n, determine number of rows (n
vv))
nn
vv = Z = Z
WQWQ / 4 / 4
n
v
= 5

83. A
Perforated Riser or Plate Perforated Riser or Plate
OutletOutlet
= 1.62/(0.013*3.0
2
+0.22*3.0–0.1)
= (4*2.4/π)
1/2
3.0
2.4
1.75
1
1.75
NA
9
= (4/π*2.4/1)
1/2
= (Z
WQ
*12in)/4

84. A
V-Notch Weir OutletV-Notch Weir Outlet
Dr. Robert Pitt Source: Hubbard Brook LTER

85. A
V-Notch Weir OutletV-Notch Weir Outlet
= 0.5*3.0ft
= (1.62*43,560)/(40*3600)

86. A
V-Notch Weir OutletV-Notch Weir Outlet
Calculate required v-notch weir angle Calculate required v-notch weir angle
(calculator in radians)(calculator in radians)
θ = 2 * (180 / π) * arctan (Qθ = 2 * (180 / π) * arctan (Q
WQWQ/(C/(C
vv * H * H
WQWQ
5/25/2
))))
CV = V-notch weir coefficient = 2.5CV = V-notch weir coefficient = 2.5
If calculator is set to degrees useIf calculator is set to degrees use
θ = 2* arctan (Qθ = 2* arctan (Q
WQWQ/(C/(C
vv * H * H
WQWQ
5/25/2
))))
Source: Hubbard Brook
LTER
θ

87. A
V-Notch Weir OutletV-Notch Weir Outlet
If θ is <20º set θ to 20ºIf θ is <20º set θ to 20º
Calculate top width of v-notch weir Calculate top width of v-notch weir
(W(W
VV))
WW
vv = 2 * Z = 2 * Z
WQWQ * Tan ( * Tan (θ / 2)θ / 2)
Source: Hubbard Brook
LTER
θ

88. A
V-Notch Weir OutletV-Notch Weir Outlet
= 2*(180/π)*arctan(0.49/(2.5*1.5
5/2
))
Since Since θθ < 20º set < 20º set θθ to 20º to 20º
= 2*3.0*tan(8º/2)

89. A
Pool ShapePool Shape
3W
W

90. A
Water BudgetWater Budget
Recommended to Recommended to
ensure permanent ensure permanent
poolpool
Chapter 13 the Chapter 13 the
NRCS NRCS Engineering Engineering
Hand BookHand Book
outin
QQ
time
storage
-=
D
D

91. A
ForebayForebay
Volume (VolVolume (Vol
FBFB) should be at least 10% of WQv) should be at least 10% of WQv
Depth (ZDepth (Z
FBFB) should be at least 3feet) should be at least 3feet
Sides and bottom paved or hardenedSides and bottom paved or hardened
Surface area (ASurface area (A
FBFB):):
AA
FBFB = Vol = Vol
FBFB / Z / Z
FBFB

92. A
ForebayForebay
= 0.10*1.62
= 0.16/3.0
Topeka KS

93. A
Littoral BenchLittoral Bench
Serves as a planting Serves as a planting
surface and safety surface and safety
feature around feature around
perimeter of permanent perimeter of permanent
pool pool
25% to 50% of 25% to 50% of
permanent pool permanent pool
surface areasurface area
At least 10 feet wide At least 10 feet wide
with a max slope of 6:1with a max slope of 6:1
6 to 12 inches below 6 to 12 inches below
permanent pool water permanent pool water
surface surface

94. A
Littoral BenchLittoral Bench
( )
( )
π
43,560A
2π
43,560A
W
Pool
LB
LB
=
Width of Littoral Bench (W
LB
):

95. A
Littoral BenchLittoral Bench
Min=0.25*0.82, Max=0.5*0.82
Min= (0.21*43560)/(2π*(0.82*43560/ π)
1/2
)
Between W
LB
Min and W
LB
Max

96. A
VegetationVegetation
Plant berms and Plant berms and
sloped areas with sloped areas with
native grasses native grasses
Littoral bench should Littoral bench should
be planted with native be planted with native
wetland specieswetland species
Plant trees and shrubs Plant trees and shrubs
around perimeter of around perimeter of
site site
Appendix A in BMP Appendix A in BMP
manualmanual

97. A
Questions?Questions?

98. A
Extended Detention WetlandExtended Detention Wetland
Key Design FeaturesKey Design Features
Permanent Permanent
poolpool

Low marshLow marsh

High marsh High marsh

Forebay Forebay

MicropoolMicropool
Outlet structureOutlet structure
Water budgetWater budget
Wetland shapeWetland shape

99. A
Extended Detention WetlandExtended Detention Wetland
Permanent Pool VolumePermanent Pool Volume
Use Method 1 or Method 2 – same as in Extended Use Method 1 or Method 2 – same as in Extended
Wet Detention Basin DesignWet Detention Basin Design
Choose larger volume as permanent pool volume.Choose larger volume as permanent pool volume.

100. A
Extended Detention Wetland Extended Detention Wetland
(EDW)(EDW)
6-18 in
0-6 in
4-6 ft
4-6 ft

101. A
20%
40%
20%
20%
Permanent PoolPermanent Pool
Design Volume AllocationsDesign Volume Allocations

102. A
= 4.1*0.2
= 4.1*0.2
= 4.1*0.4
= 4.1*0.2
Permanent PoolPermanent Pool
Design Volume AllocationsDesign Volume Allocations

103. A
Forebay ConsiderationsForebay Considerations
Pre-sedimentation at entry to EDWPre-sedimentation at entry to EDW

Capacity to contain 5 years of Capacity to contain 5 years of
sedimentsediment
Separated from EDW with berm, Separated from EDW with berm,
gabion, or riprapgabion, or riprap

104. A
EDW ForebayEDW Forebay
Use VUse V
ForebayForebay from step II and SA from step II and SA
ForebayForebay from step III to from step III to
find forebay depth (Zfind forebay depth (Z
ForebayForebay))
ZZ
ForebayForebay = V = V
ForebayForebay/SA/SA
ForebayForebay
Depth should be 4-6feetDepth should be 4-6feet

105. A
EDW ForebayEDW Forebay

106. A
Micropool ConsiderationsMicropool Considerations
Prevents clogging of outlet Prevents clogging of outlet
4-6 feet deep4-6 feet deep
Should be surrounded by a safety shelfShould be surrounded by a safety shelf

107. A
EDW MicropoolEDW Micropool
Using the same method used to calculate the Using the same method used to calculate the
forebay:forebay:
ZZ
MicropoolMicropool = V = V
MicropoolMicropool/SA/SA
MicrpoolMicrpool
Depth should be 4 to 6 feetDepth should be 4 to 6 feet
Safety bench should be Safety bench should be ≥ 12 feet≥ 12 feet

108. A
EDW EDW
Water Quality OutletWater Quality Outlet
Depth of water quality volume above permanent Depth of water quality volume above permanent
poolpool

Consider survivability of plant species Consider survivability of plant species

Maximum depth should be 2 feet or lessMaximum depth should be 2 feet or less
Single Orifice, Orifice Plate or Standpipe, and V-Single Orifice, Orifice Plate or Standpipe, and V-
notch outlet examples in Manualnotch outlet examples in Manual
Sized for 40 hour drawdownSized for 40 hour drawdown

109. A
ShapeShape
Flowpath length (L) to permanent pool width (W) Flowpath length (L) to permanent pool width (W)
ratio must be greater than 3:1ratio must be greater than 3:1
Place berms or high marsh wedges at 50-foot Place berms or high marsh wedges at 50-foot
intervals perpendicular to the flow direction to intervals perpendicular to the flow direction to
increase dry weather flowpath lengthincrease dry weather flowpath length
Wedge-shaped, narrowest at the inlet and widest Wedge-shaped, narrowest at the inlet and widest
at the outletat the outlet
L
W

110. A
VegetationVegetation
Wetland vegetation should occupy 50-75% of surface Wetland vegetation should occupy 50-75% of surface
areaarea
Develop a landscaping plan, which places appropriate Develop a landscaping plan, which places appropriate
species in each EDW zone and the surrounding area species in each EDW zone and the surrounding area
For plantings, use soil from an existing wetland or a For plantings, use soil from an existing wetland or a
designed wetland planting mixdesigned wetland planting mix
Kansas City, MO

111. A
Questions?Questions?
15 minute break15 minute break

112. A
Design ActivityDesign Activity
UMKC Rain Garden Project

113. A
Activity Activity
Design an extended wet detention basin to capture Design an extended wet detention basin to capture
runoff from a 42 acre drainage area with mixed land runoff from a 42 acre drainage area with mixed land
use. Size the permanent pool and WQv of the basin use. Size the permanent pool and WQv of the basin
using a v-notch outlet structure that will release the using a v-notch outlet structure that will release the
WQv over a period of 40 hours.WQv over a period of 40 hours.

114. A
Activity - Design an EWDBActivity - Design an EWDB

115. A
Activity ResultsActivity Results

116. A
Lecture 3Lecture 3
Other ConsiderationOther Consideration
Vegetation Vegetation
Operations and maintenance Operations and maintenance
ImplementationImplementation

PlanningPlanning

DesignDesign

ConstructionConstruction
Lesson’s learned Lesson’s learned

117. A
Vegetation
Process

Design

Review

Standards

Construction

Adaptive Management &
Maintenance
Buy-in

Project Sponsor

Public/Stakeholders
Education

Aesthetics

Establishment

Benefits and challenges
Success

Realistic

118. A
VegetationVegetation
Use plants listed in the BMP Manual Appendix A Use plants listed in the BMP Manual Appendix A
“Recommended Plant Materials for BMPs”“Recommended Plant Materials for BMPs”
Narrow down from this list by:Narrow down from this list by:

Treatment only, habitat creation / biodiversity, Treatment only, habitat creation / biodiversity,
aesthetics?aesthetics?
•If treatment is most important, then a wetland seed If treatment is most important, then a wetland seed
mix may be sufficient. mix may be sufficient.
•If habitat creation and biodiversity is desired, specific If habitat creation and biodiversity is desired, specific
species with habitat benefits are recommendedspecies with habitat benefits are recommended

Evaluating site conditions - soil quality, climate, Evaluating site conditions - soil quality, climate,
wetness, pollutionwetness, pollution
•Hardier plants would work better in areas with poorer Hardier plants would work better in areas with poorer
site conditionssite conditions

119. A
VegetationVegetation
Narrow down from this list by (cont):Narrow down from this list by (cont):

Speaking with local nursery or botanistsSpeaking with local nursery or botanists
•What plants are available for purchase?What plants are available for purchase?
•Which plants have the best survivability?Which plants have the best survivability?
•Which plants would be best candidates for wet areas, Which plants would be best candidates for wet areas,
variable moisture, poor soils, etc.?variable moisture, poor soils, etc.?

Visit at natural wetland in the areaVisit at natural wetland in the area
•What plants are naturally favored in local area?What plants are naturally favored in local area?
•Are there specific invasive species that need to be Are there specific invasive species that need to be
managed?managed?

Check municipal codes to ensure all plant materials Check municipal codes to ensure all plant materials
are approved for the areaare approved for the area

120. A
Wetland Species

121. A
Nuisance Species

122. A
Nuisance Species

123. A
Native versus Non-native Native versus Non-native
PlantsPlants
Native plants are Native plants are
recommendedrecommended

Larger root systemLarger root system

Increase infiltrationIncrease infiltration

More drought More drought
toleranttolerant

Disease resistantDisease resistant

Adapted to Adapted to
environmentenvironment

124. A
Native Plants-Advantages and
Disadvantages
Advantages
Indigenous to the area and able to thrive in the local climate with
less maintenance.
Deep roots enhance stormwater infiltration into the soil.
Able to withstand flooding events as well as extended dry
periods.
Reduces flow velocity of stormwater runoff.
Wide range of application (restoration of native prairie, woodland,
wetlands, & riparian areas)
Attracts wildlife and improves biological diversity.
Requires little to no fertilizer or chemical maintenance
Requires less water to survive.
Provides attractive and natural vegetative scenery.
Disadvantages
Can be difficult to establish if some circumstances.
Can be expenses if planted from nursery stock plugs.
Can be considered “weedy” by some people.

125. A
Vegetation – Design
Consideration
Local and regional planning initiatives
Public involvement/public relations
Visibility-Aesthetics
Height of vegetation
Financial (funding source, budget, property values)
Regulatory requirements
Function/risk
Utility-stormwater management
Recreation

126. A
Vegetation ResourcesVegetation Resources
Appendix A in the MARC BMP manualAppendix A in the MARC BMP manual
Local nurseriesLocal nurseries
www.kansasnativeplantsociety.orgwww.kansasnativeplantsociety.org
www.grownative.orgwww.grownative.org
http://plants.usda.gov

127. A
Other Sources
Tallgrass Restoration Handbook for Prairies Savannas and
Woodlands (Packard & Mutel, 1997)
The National List of Plant Species that Occur in Wetlands-
Region 3 (USFWS, 1988)
The Flora of Missouri (Steyermark, 1963; 1996)
Steyermark’s Flora of Missouri, Volume I, II,…; Yatskeievych;
1999…)
The Flora of the Great Plains (McGregor et. al.)
Ecologist; Landscape Architect

128. A
Vegetation Examples Vegetation Examples
BanksBanks

Butterfly Milkweed, Butterfly Milkweed,
Asclepias tuberosaAsclepias tuberosa
Littoral BenchLittoral Bench

Blunt SpikerushBlunt Spikerush, ,
Eleocharis obtusaEleocharis obtusa
Clarence A. Rechenthin @ USDA-NRCS PLANTS Database
Robert H. Mohlenbrock @ USDA-NRCS PLANTS Database

129. A
Vegetation – Other Design
Consideration
Setting

Urban

Rural
Built Environment

Commercial

Residential

Mixed Use
Stormwater Utility – Stormwater Management
Recreation
CONTEXT

130. A
Vegetation – Installation &
Maintenance
Installation

Oversight

Contractor Experience

Plant availability
Maintenance Measures

Has a maintenance program/budget been established?

What type of adaptive management will be implemented?
•Burning or mowing
•Herbicides
•Transplanting

Who will do the management-establishment?
•Lawn maintenance crews
•Native Landscape specialists

131. A
General MaintenanceGeneral Maintenance
Event Inspection (> 0.5 inches)Event Inspection (> 0.5 inches)

Inspect facility operation, especially outlet structureInspect facility operation, especially outlet structure

Remove trash & debrisRemove trash & debris

Document potential problemsDocument potential problems
Monthly InspectionMonthly Inspection

Inspect & repair erosionInspect & repair erosion

Water plant material during dry periods (1Water plant material during dry periods (1
stst
Year) Year)

Perform routine plant maintenance (pruning, weeding, etc.)Perform routine plant maintenance (pruning, weeding, etc.)
Semi-Annual InspectionSemi-Annual Inspection

Remove and replace dead or diseased vegetationRemove and replace dead or diseased vegetation

Re-landscape/re-mulch any area areasRe-landscape/re-mulch any area areas
Annual InspectionAnnual Inspection

Inspect inlet & outlet structure conditionInspect inlet & outlet structure condition

Record assessment of planted species & evidence of invasive Record assessment of planted species & evidence of invasive
plant speciesplant species

Perform comprehensive safety inspectionPerform comprehensive safety inspection

132. A
Other MaintenanceOther Maintenance
ConsiderationConsideration
Maintenance access - 15 Maintenance access - 15
feet wide strip around feet wide strip around
the perimeter of the sitethe perimeter of the site
May need to harvest May need to harvest
excess plantsexcess plants
Erosion issuesErosion issues
Sediment removal from Sediment removal from
forebay when 50% fullforebay when 50% full
Sediment removal from Sediment removal from
micropool and marsh micropool and marsh
area when 10 to 15% fullarea when 10 to 15% full

133. Design Phase
– Erosion and
sedimentation
controls
– Post-construction
BMPs
– Flood control
improvements
Construction Phase
– Inspect and maintain
BMPs for construction
activities
– Construct Post
Construction BMPs
– Maintain agreements for
post-construction BMPs
DesignerDesigner
Planning Phase
– Environmental Site
Assessment
– Select Post
Construction BMPs
– Flood Control Study
– Establish Long-term
Maintenance Agreements
Review Team
Planning
Engineering
Parks & Recreation
Environmental Specialists
Attorney Review Team
Planning
Engineering
Parks & Recreation
Environmental Specialists
Operations & Maintenance
Review Team
Planning
Engineering
Code Compliance
Inspectors
Plat
Approval
Occupancy
Permit
Building
Permit

134. A
Upcoming Training SessionsUpcoming Training Sessions
Module #3 – Rain Gardens & BioretentionModule #3 – Rain Gardens & Bioretention

Date: January 23, 2009Date: January 23, 2009

Location: Helzberg Auditorium, KCPLLocation: Helzberg Auditorium, KCPL
Module #4 – Extended Dry Detention & Infiltration Module #4 – Extended Dry Detention & Infiltration
(Pervious Pavements)(Pervious Pavements)

Date: February 20, 2009Date: February 20, 2009

Location: Helzberg Auditorium, KCPLLocation: Helzberg Auditorium, KCPL

135. A
Questions?
Comments.
Suggestions.