HomeMy WebLinkAbout2.a.Alternative Stormwater Management TechniquesAGENDA ITEM: Alternative Stormwater Management
Techniques
AGENDA SECTION:
ISUaSC 10 N
PREPARED BY: Andrew J. Brotzler, PE, City Engineer'
fre
AGENDA NO. 2.k
ATTACHMENTS: Fact Sheets
APPROVED BY:
RECOMMENDED ACTION: Discussion
4 ROSEMOUNT
CITY COUNCIL
City Council Work Session: January '10, 2007
EXECUTIVE SUMMARY
BACKGROUND
Over the past year, Council members may have reviewed, discussed or received mformation on newly
emerging approaches to stormwater management that are being considered or implemented with projects.
Probably the most common approach that has received a significant amount of pubhcation is ram gardens.
There are a number of additional techniques that may be considered as part of a stormwater management
system with many techniques being highlighted as part of "Green" or "Sustainable" development
strategies.
In consideration of these emerging approaches, staff has worked with Andi Moffatt and other water
resource specialists to review a vanety of approaches that may be incorporated into projects as part of a
stormwater management system. Attached for information are Fact Sheets that have been developed as
Alternative Stormwater Management Techniques to traditional methods. As noted m a number of the
attached sheets, retaining water on -site and utilizing infiltranon to manage stormwater and reduce impacts
to downstream water bodies is a common theme. In developmg these Alternative Stormwater
Management Techniques, it was noted that the City of Rosemount is very advanced with this approach
based on the required development of infiltrauon basins m newly developing areas.
At the meeting, Andi Moffatt and Phil Belfion will introduce the Fact Sheets to Council and respond to
questions. As part of the review of these stormwater management techniques, a number of factors will
need to be considered related to the implementation of all or some of the techniques. These factors may
include ordinance updates to require the implementation of alternative techniques to a bonus /incentive
system to promote the utihzauon of alternative techniques with new projects.
SUMMARY
Based on Council review and consideration of these alternative techniques, additional review and
discussion may be necessary to work towards the implementation of these techniques.
G \Storm Utilities \AltemauveTedauquesCWS1 -10 -07 doc
Benefits
Removes 70 -90% total suspend solids
Removes 40 -60% total phosphorus
Provides flood protection to adjacent
property
Potential to provide volume reduction
with infiltration design elements
Provides rate control of storm water
runoff
Prevents /reduces downstream flooding
Provides pollutant removal with minimal
annual maintenance effort
Wet Pond
(NURP Pond)
Definition: Ponding area that ains an
area of open water to capture and ore a
certain volume of runoff to provide water
quality treatment.
Purpose: Provide storm water treatment by
storing water until sediment and nutrients
are removed by gravity, absorption, or plant
uptake. The pond also provides storage of
flood waters above the normal outlet to
protect adjacent and downstream properties.
Construction Methods: Excavation of upland
areas dedicated for drainage purposes.
Maintenance Activities: Remove
accumulated sediment every 10 -20 years.
Potential Drawbacks
Reduces developable area
Safety concerns
Algae blooms may occur
Improperly designed ponds may have
limited vegetation and cause shoreline
erosion
Other Considerations: Ponds should be designed with a shallow bench to allow for maintenance
and safety
1
1
WS
Ine
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
Fair
0 Poor
Wet Ponds (NURP Ponds)
1
1
0
High
Low
Low
Benefits
Removes 70 -90% total suspend solids
Removes 40 -60% total phosphorus
Provides flood protection to adjacent
property
Potential to provide volume reduction
with infiltration design elements
Provides rate control of storm water
runoff
Prevents /reduces downstream flooding
Provides pollutant removal with minimal
annual maintenance effort
Wet Pond
(NURP Pond)
Definition: Ponding area that ains an
area of open water to capture and ore a
certain volume of runoff to provide water
quality treatment.
Purpose: Provide storm water treatment by
storing water until sediment and nutrients
are removed by gravity, absorption, or plant
uptake. The pond also provides storage of
flood waters above the normal outlet to
protect adjacent and downstream properties.
Construction Methods: Excavation of upland
areas dedicated for drainage purposes.
Maintenance Activities: Remove
accumulated sediment every 10 -20 years.
Potential Drawbacks
Reduces developable area
Safety concerns
Algae blooms may occur
Improperly designed ponds may have
limited vegetation and cause shoreline
erosion
Other Considerations: Ponds should be designed with a shallow bench to allow for maintenance
and safety
1
1
WS
Ine
Benefits
Can remove up to 100% total suspended
solids
Can remove up to 100% of total
phosphorus
Provides groundwater recharge
Reduces the volume of runoff discharged
off site
Provides rate control
Reduces /prevents downstream flooding
Assists in meeting NPDES Nondegradation
volume requirements
Definition. A depressional area t collects
and infiltrates storm water runoff uo the soil.
Purpose: Reduce storm water runoff volume
and discharge rates.
Construction Methods: Infiltration area is
graded; soil is scarified and loosened to avoid
compaction; may include rock or sand
trenches or soil amendments to aid in
infiltration.
Maintenance Activities: Maintenance is
required to remove sediment, debris and
excessive vegetation to keep the basin
functioning as designed.
Potential Drawbacks
Land uses need to be evaluated to limit
risk of pollutant transfer to groundwater
Requires frequent maintenance to remove
vegetation and debris
Infiltration not available when ground is
frozen
Reduces developable area
Other Considerations: Works best in sandy soils; use caution if implementing in wellhead protection area.
Pretreatment should be provided prior to discharge to an infiltration basin; vegetation should be carefully
selected to avoid unsightly basins.
1
p
WSO
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
Fair
0 Poor
Infiltration Basin
High
Low
Medium
Benefits
Can remove up to 100% total suspended
solids
Can remove up to 100% of total
phosphorus
Provides groundwater recharge
Reduces the volume of runoff discharged
off site
Provides rate control
Reduces /prevents downstream flooding
Assists in meeting NPDES Nondegradation
volume requirements
Definition. A depressional area t collects
and infiltrates storm water runoff uo the soil.
Purpose: Reduce storm water runoff volume
and discharge rates.
Construction Methods: Infiltration area is
graded; soil is scarified and loosened to avoid
compaction; may include rock or sand
trenches or soil amendments to aid in
infiltration.
Maintenance Activities: Maintenance is
required to remove sediment, debris and
excessive vegetation to keep the basin
functioning as designed.
Potential Drawbacks
Land uses need to be evaluated to limit
risk of pollutant transfer to groundwater
Requires frequent maintenance to remove
vegetation and debris
Infiltration not available when ground is
frozen
Reduces developable area
Other Considerations: Works best in sandy soils; use caution if implementing in wellhead protection area.
Pretreatment should be provided prior to discharge to an infiltration basin; vegetation should be carefully
selected to avoid unsightly basins.
1
p
WSO
Photo from the City of Maplewood
Benefits
Provides some water quality treatment
Provides rate control for very small
storm events
Provides groundwater recharge
Reduces some runoff volume
Maintained gardens can be attractive
Can work in older residential areas
where no treatment is provided
Definition: Depressional landscaped area
created on a site-by-site basis t
encourages infiltration of storm eater
Purpose: Provide water quality treatment
and volume reduction through plant uptak
and infiltration.
Construction Methods: Areas are excavated
and may be filled with sand and organic
matenal. Native or garden variety plants
c. are installed to provide a visually
appealing, landscaped runoff retention an
infiltration area.
t Maintenance Activities: Annual removal of
sediment and vegetation maintenance, at
mi nimum.
G
Potential Drawbacks
Requires frequent debris removal and
vegetation maintenance
Not suitable for sites with high water
table or poorly drained soils
Limited historical data on long -term
function and maintenance needs
Does not provide flood protection or
storm water storage for large storm
events
May not function during snow melt
conditions
Other Considerations: This BMP may be a good option where residents are interested in gardening and
maintaining these areas Responsible party for ong -term maintenance needs to be carefully considered.
A
WS
SI WI(
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
Fair
0 Poor
Ram Gardens
1
1
0
1
Low
High
High
Photo from the City of Maplewood
Benefits
Provides some water quality treatment
Provides rate control for very small
storm events
Provides groundwater recharge
Reduces some runoff volume
Maintained gardens can be attractive
Can work in older residential areas
where no treatment is provided
Definition: Depressional landscaped area
created on a site-by-site basis t
encourages infiltration of storm eater
Purpose: Provide water quality treatment
and volume reduction through plant uptak
and infiltration.
Construction Methods: Areas are excavated
and may be filled with sand and organic
matenal. Native or garden variety plants
c. are installed to provide a visually
appealing, landscaped runoff retention an
infiltration area.
t Maintenance Activities: Annual removal of
sediment and vegetation maintenance, at
mi nimum.
G
Potential Drawbacks
Requires frequent debris removal and
vegetation maintenance
Not suitable for sites with high water
table or poorly drained soils
Limited historical data on long -term
function and maintenance needs
Does not provide flood protection or
storm water storage for large storm
events
May not function during snow melt
conditions
Other Considerations: This BMP may be a good option where residents are interested in gardening and
maintaining these areas Responsible party for ong -term maintenance needs to be carefully considered.
A
WS
SI WI(
Other Considerations: System can assist in meeting
TMDL and nondegradation requirements
Benefits
Chemical floc can virtually eliminate all
nutrients from the system to meet water
quality standards
Can guarantee treatment to a required
standard
Provides groundwater recharge
Provides water quality treatment
Reduces the volume of runoff
Infiltration bed is less susceptible to
plugging and requires less maintenance
Reduces /prevents downstream flooding
Provides rate control
Infiltration may be available during frozen
ground conditions
,n
RESTORE Pond
Definition: A Regional, Enhanced
Stormwater Treatment and Outdoor
r Recreation Environment. his is a multi
receives storm
water, infiltrates the runoff into the soil,
and treats the nmoff through a
combination or detention and chemical
treatment (Iron or Alum).
Purpose: Reduce downstream nutrients
and storm water runoff volume.
Construction Methods: Chemical is
injected or sprayed into the treated
infiltration system; pumping tank and
access route are provided; 2nd cell may
include a pump to regularly treat water.
Maintenance Activities: Pump system
should be regularly maintained; tank
should be filled and treatment pond
i should be excavated to remove pollutants
and flocculants.
1
Potential Drawbacks
Permitting of chemical system may be
needed
Regular maintenance and disposal of
flocculent is needed
Systems may require frequent
maintenance
Groundwater not protected from
pollutant
WSB
nt
uality Treatment
ne Reduction
louuoD all
water Recharge
Tature Control
Requirements
'ound of Pollutant
lemoved
Annual Maintenance Cost
Key Excellent
1 Fair
0 Poor
RESTORE Pond
High
High
I Iigh
Other Considerations: System can assist in meeting
TMDL and nondegradation requirements
Benefits
Chemical floc can virtually eliminate all
nutrients from the system to meet water
quality standards
Can guarantee treatment to a required
standard
Provides groundwater recharge
Provides water quality treatment
Reduces the volume of runoff
Infiltration bed is less susceptible to
plugging and requires less maintenance
Reduces /prevents downstream flooding
Provides rate control
Infiltration may be available during frozen
ground conditions
,n
RESTORE Pond
Definition: A Regional, Enhanced
Stormwater Treatment and Outdoor
r Recreation Environment. his is a multi
receives storm
water, infiltrates the runoff into the soil,
and treats the nmoff through a
combination or detention and chemical
treatment (Iron or Alum).
Purpose: Reduce downstream nutrients
and storm water runoff volume.
Construction Methods: Chemical is
injected or sprayed into the treated
infiltration system; pumping tank and
access route are provided; 2nd cell may
include a pump to regularly treat water.
Maintenance Activities: Pump system
should be regularly maintained; tank
should be filled and treatment pond
i should be excavated to remove pollutants
and flocculants.
1
Potential Drawbacks
Permitting of chemical system may be
needed
Regular maintenance and disposal of
flocculent is needed
Systems may require frequent
maintenance
Groundwater not protected from
pollutant
WSB
nt
Benefits
Prevents /reduces downstream flooding
potential
Provides flood protection to adjacent
properties
Provides rate control of storm water
runoff
Can be designed for dual purposes
such as park areas /parking lots /athletic
fields
Dry Pond
Definition. A depressional area that
temporarily stores storm water runoff.
Purpose: Reduce risk of flooding by
temporarily storing storm water runoff.
Construction Methods: The area is
graded; outlet structure is constructed.
:Maintenance Activities: Clean out of
sediment and trash that is collected in
the basin; outlet structure can be
designed to catch trash in localized area.
May develop mud flats and look
unattractive if vegetation is not properly
selected or maintained
Vegetation may have difficulty establishing
due to frequent water fluctuations
Provides limited treatment of runoff
Sediment deposited in basin may be
resuspended in large storm events
Reduces developable area
Potential Drawbacks
Other Considerations: The length of time that an area will be inundated with water will determine the
type of vegetation and uses that may occur within the dry pond area.
1
WS
'0,000,>
IC
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
1 Fair
0 Poor
Dry Ponds
1
1
1
0
High
Low
Low
Benefits
Prevents /reduces downstream flooding
potential
Provides flood protection to adjacent
properties
Provides rate control of storm water
runoff
Can be designed for dual purposes
such as park areas /parking lots /athletic
fields
Dry Pond
Definition. A depressional area that
temporarily stores storm water runoff.
Purpose: Reduce risk of flooding by
temporarily storing storm water runoff.
Construction Methods: The area is
graded; outlet structure is constructed.
:Maintenance Activities: Clean out of
sediment and trash that is collected in
the basin; outlet structure can be
designed to catch trash in localized area.
May develop mud flats and look
unattractive if vegetation is not properly
selected or maintained
Vegetation may have difficulty establishing
due to frequent water fluctuations
Provides limited treatment of runoff
Sediment deposited in basin may be
resuspended in large storm events
Reduces developable area
Potential Drawbacks
Other Considerations: The length of time that an area will be inundated with water will determine the
type of vegetation and uses that may occur within the dry pond area.
1
WS
'0,000,>
IC
E At
Photo from Low er Columbia River Partnership
Benefits
Removes sediment and nutrients from
storm water runoff
Can be designed to infiltrate storm
water runoff
Provides limited reduction in storm
water runoff rates
Definition: A depressional area at is
events generally dry between storm and has
been amended with sand, gravel, or other
media to filter pollutants from storm water.
Purpose: Reduce pollutants and volume of
storm water by filtering the water through
sandy media.
Construction Methods: A depressional area
is graded and amended with sand, gravel, or
other media. Underdrams are generally used A
to collect and convey the filtered water away
from the area.
Maintenance Activities: Removal of sediment
and trash that is collected in the area; outlet
structure can be designed to catch trash in
localized area.
Potential Drawbacks
Expensive to replace filter media
Filtration media can clog if water is not
pretreated for coarse sediments
Requires frequent maintenance to insure
proper performance
Other Considerations: Pretreatment to trap coarse sediments should be used prior to water being
directed to the filter.
1
WJB
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key Excellent
Fair
0 Poor
Sand Filters
1
1
1
I
High
High
High
E At
Photo from Low er Columbia River Partnership
Benefits
Removes sediment and nutrients from
storm water runoff
Can be designed to infiltrate storm
water runoff
Provides limited reduction in storm
water runoff rates
Definition: A depressional area at is
events generally dry between storm and has
been amended with sand, gravel, or other
media to filter pollutants from storm water.
Purpose: Reduce pollutants and volume of
storm water by filtering the water through
sandy media.
Construction Methods: A depressional area
is graded and amended with sand, gravel, or
other media. Underdrams are generally used A
to collect and convey the filtered water away
from the area.
Maintenance Activities: Removal of sediment
and trash that is collected in the area; outlet
structure can be designed to catch trash in
localized area.
Potential Drawbacks
Expensive to replace filter media
Filtration media can clog if water is not
pretreated for coarse sediments
Requires frequent maintenance to insure
proper performance
Other Considerations: Pretreatment to trap coarse sediments should be used prior to water being
directed to the filter.
1
WJB
m�cmuµlll�� I uui�wuulr��
Pho» !tom Tr sacra _y ivLri:csota Duluth
Benefits
Provides temporary storage of storm
water
Reduces surface space requirements for
storm water storage
Design could incorporate infiltration,
depending on site conditions to reduce
runoff volume
n i group .age
Infiltration System
Definition: Holding facility designed to
retain and /or infiltrate storm water
underground prior to discharge.
Purpose: Provides temporary storage of
storm water runoff while preserving
surface space and reducing peak runoff
flow rates and flow volume.
Construction Methods: Storm water
storage may occur in pipe galleries or tanks
placed underground Often times these
systems are installed under parking areas
to minimize land requirements.
Maintenance Activities: Tanks need to be
inspected at least annually and debris and
sediment removed.
Potential Drawbacks
Poor sediment and nutrient removal; can
be improved with infiltration
Requires annual cleaning and inspection
Costly to construct
Replacement cost very expensive
Other Considerations: Pipes and tanks should be designed to prevent freezing.
O/•
Key:
0
Excellent
Fair
Poor
Underground Storage Systems
No Infiltration /With Infiltration
O/•
O
O/•
1/
t ow
High
High
WS B
Benefits
Reduces sediment and other pollutants
from runoff
Reduces volume of storm water runoff
Provides habitat and biological diversity
tated n
Filter Strips
Potential Drawbacks
O Definition: A vegetated section of and
designed to accept overland runoff and filter
water through the vegetation. e areas
occur as depressions, shallow channels, or as a
vegetation break between developed areas.
Purpose: Reduce pollutants from storm water
by filtering the water through vegetation such
as buffers and swales.
Construction Methods: The swale /strip is
graded if needed or left in its natural state.
The area is planted with suitable vegetation
natural vegetation is preserved.
Maintenance Activities: Removal of sedimen
and trash that is collected in the area; outlet
structure can be designed to catch trash in
localized area.
Vegetation should remain unmowed;
residents may not find area aesthetically
pleasing
Encroachment by landowners can become
an issue
Annual inspections should be undertaken to
review health of vegetation and to remove
debris and excess sediment
Other Considerations: Rate of sheet flow in swale should be taken into account to avoid erosion.
Mowing could occur twice per year to manage healthy vegetation.
K hruunle, 1
IC
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
4
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
A
IAA
Key: Excellent
1 Fair
0 Poor
Vegetated Swales
1
1
1
1
Medium
Low
Medium
Benefits
Reduces sediment and other pollutants
from runoff
Reduces volume of storm water runoff
Provides habitat and biological diversity
tated n
Filter Strips
Potential Drawbacks
O Definition: A vegetated section of and
designed to accept overland runoff and filter
water through the vegetation. e areas
occur as depressions, shallow channels, or as a
vegetation break between developed areas.
Purpose: Reduce pollutants from storm water
by filtering the water through vegetation such
as buffers and swales.
Construction Methods: The swale /strip is
graded if needed or left in its natural state.
The area is planted with suitable vegetation
natural vegetation is preserved.
Maintenance Activities: Removal of sedimen
and trash that is collected in the area; outlet
structure can be designed to catch trash in
localized area.
Vegetation should remain unmowed;
residents may not find area aesthetically
pleasing
Encroachment by landowners can become
an issue
Annual inspections should be undertaken to
review health of vegetation and to remove
debris and excess sediment
Other Considerations: Rate of sheet flow in swale should be taken into account to avoid erosion.
Mowing could occur twice per year to manage healthy vegetation.
K hruunle, 1
IC
Benefits
Alternative for difficult locations
Removes coarse sediment
Removes floatables
In-line Tre
Structures
Definition: Structure system connected
directly with the storm sewer system totrea
storm water. Includes products such as
DramPac, HydroKleen, Stormceptor, and
Vortechnics.
Purpose: Remove floating pollutants and
suspended solids from runoff.
Construction Methods: Often precast
concrete installed with storm sewer system.
Maintenance Activities: Regular and annual
maintenance with vacuum truck.
Potential Drawbacks
Poor nutrient removal
Requires frequent maintenance with
vacuum truck
Maintenance agreement needed for
privately installed systems
Other Considerations: There are many manufacturers of these systems; consideration should be given
to the system that will work best for the location. Manufactures starting to include nutrient removal
systems, but these systems are costly and require additional maintenance
WS
lnotial
Water Quality Treatment
Volume Reduction
r
Rate Control 1
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
Fair
0 Poor
In -Line Treatment
Structures
I
O
O
O
O
Low
High
High
Benefits
Alternative for difficult locations
Removes coarse sediment
Removes floatables
In-line Tre
Structures
Definition: Structure system connected
directly with the storm sewer system totrea
storm water. Includes products such as
DramPac, HydroKleen, Stormceptor, and
Vortechnics.
Purpose: Remove floating pollutants and
suspended solids from runoff.
Construction Methods: Often precast
concrete installed with storm sewer system.
Maintenance Activities: Regular and annual
maintenance with vacuum truck.
Potential Drawbacks
Poor nutrient removal
Requires frequent maintenance with
vacuum truck
Maintenance agreement needed for
privately installed systems
Other Considerations: There are many manufacturers of these systems; consideration should be given
to the system that will work best for the location. Manufactures starting to include nutrient removal
systems, but these systems are costly and require additional maintenance
WS
lnotial
Benefits
Reduces storm water runoff discharged
downstream
Provides groundwater recharge
Assists in maintaining bituminous road
edge in rural section road construction
Reduces need for storm sewer system
construction
Residents maintain right -of -way in same
manner as traditional neighborhood
concrete Definition: Flat, at-grade "curb"
r Purpose: Allows storm water to sheet flo
off from street into adjacent e to allo
infiltration Provides "hard
I edge" to bituminous rural section roads.
Construction Methods: Bituminous rural
section road with concrete ribbon as "curb
`I Maintenance Activities: Typical street
I. maintenance and management.
Section
Potential Drawbacks
Infiltration in adjacent swales may not
occur during snow melt conditions
Parking may occur on grassy areas
Not suitable in areas where there is no
space for swales or ditches to convey
storm water runoff
WSB
Water Quality Treatment
Volume Reduction 1
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
1
Cost Per Pound of Pollutant
Removed
A nnual Maintenance Cost
Key: Excellent
1 Fair
0 Poor
Rural Street Curb Section
1
1
1
1
Low
Low
Low
Benefits
Reduces storm water runoff discharged
downstream
Provides groundwater recharge
Assists in maintaining bituminous road
edge in rural section road construction
Reduces need for storm sewer system
construction
Residents maintain right -of -way in same
manner as traditional neighborhood
concrete Definition: Flat, at-grade "curb"
r Purpose: Allows storm water to sheet flo
off from street into adjacent e to allo
infiltration Provides "hard
I edge" to bituminous rural section roads.
Construction Methods: Bituminous rural
section road with concrete ribbon as "curb
`I Maintenance Activities: Typical street
I. maintenance and management.
Section
Potential Drawbacks
Infiltration in adjacent swales may not
occur during snow melt conditions
Parking may occur on grassy areas
Not suitable in areas where there is no
space for swales or ditches to convey
storm water runoff
WSB
Photo from lower Columbia R, ei Parmcl ship
Benefits
Reduces volume of storm water runoff
Reduces impervious surfaces
Increases infiltration in areas that
previously had been paved
Pavers and Green
Parking Lots
Definition: Permeable or able
surfaces that can replace asphalt and
t concrete.
Purpose: Reduce impervious surfaces and
decrease storm water runoff volume.
Construction Methods: Construct granular
road base and place paver type materials
over top as parking lot or roadway surface.
Maintenance Activities: Mowing and
t, vegetation maintenance; may require
e irrigation.
Potential Drawbacks
Not recommended for high traffic areas
Wheelchair access may be limited
Potential snow and ice removal issues
Require regular maintenance such as
mowing, cleaning, and watering
Expensive to construct and maintain
1
WS
G 4 aocuuee Ina
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
1 Fair
0 Poor
Pavers and Green Parking
Lots
1
1
1
I
1
Low
High
High
Photo from lower Columbia R, ei Parmcl ship
Benefits
Reduces volume of storm water runoff
Reduces impervious surfaces
Increases infiltration in areas that
previously had been paved
Pavers and Green
Parking Lots
Definition: Permeable or able
surfaces that can replace asphalt and
t concrete.
Purpose: Reduce impervious surfaces and
decrease storm water runoff volume.
Construction Methods: Construct granular
road base and place paver type materials
over top as parking lot or roadway surface.
Maintenance Activities: Mowing and
t, vegetation maintenance; may require
e irrigation.
Potential Drawbacks
Not recommended for high traffic areas
Wheelchair access may be limited
Potential snow and ice removal issues
Require regular maintenance such as
mowing, cleaning, and watering
Expensive to construct and maintain
1
WS
G 4 aocuuee Ina
Benefits
Reduces storm water runoff volume
from impervious surfaces
Reduces costs for storm sewer and
ponding
1
Porous Pavement
Definition- Pavement that has the Lability
to infiltrate water.
Purpose: To reduce storm water runoff
t volume from impervious surfaces.
t
Construction Methods: Special pavement
mix and subgrade. Pavement must not be
over compacted during construction.
Maintenance Activities: Requires frequent
sweeping.
Potential Drawbacks
Requires frequent inspection and
maintenance such as sweeping or
vacuuming
Use of sand and salt for de icing needs to
be restricted
Increased pavement cost
Needs to be used in tandem with other
rate /volume control practices
Other Considerations: Works best in low traffic areas Research shows a 75% failure rate within five
years due to improper installation or maintenance.
WS B
i wrn ram. l
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cosl
Key: Excellent
Fair
0 Poor
Porous Pavement
1
1
1
1
1
Low
High
High
Benefits
Reduces storm water runoff volume
from impervious surfaces
Reduces costs for storm sewer and
ponding
1
Porous Pavement
Definition- Pavement that has the Lability
to infiltrate water.
Purpose: To reduce storm water runoff
t volume from impervious surfaces.
t
Construction Methods: Special pavement
mix and subgrade. Pavement must not be
over compacted during construction.
Maintenance Activities: Requires frequent
sweeping.
Potential Drawbacks
Requires frequent inspection and
maintenance such as sweeping or
vacuuming
Use of sand and salt for de icing needs to
be restricted
Increased pavement cost
Needs to be used in tandem with other
rate /volume control practices
Other Considerations: Works best in low traffic areas Research shows a 75% failure rate within five
years due to improper installation or maintenance.
WS B
i wrn ram. l
Benefits
Diverts water from the municipal storm
system
Reduces runoff from individual sites for
small storm events
Allows residents to use water for lawn or
gardening, thus reducing municipal
water use
Rain Barrels
Definition. An artificial reservoir for storing
rainwater from residential or commercial
Purpose: To capture rainwater for private
use and reduce storm water runoff.
Construction Methods: Purchase and place
rain barrel at end of roof gutters.
Maintenance Activities: Minimal; occasional
cleaning of barrel.
Potential Drawbacks
Not recommended for human
consumption
Systems may require seasonal
maintenance
Requires insect control
Uncovered barrels pose threat for small
children and small animals
Other Considerations: This can generally be an encouraged practice through education rather than
regulation.
WS B
If
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key Excellent
1 Fair
0 Poor
Rain Barrels
0
1
1
1
0
Low
Low
Low
Benefits
Diverts water from the municipal storm
system
Reduces runoff from individual sites for
small storm events
Allows residents to use water for lawn or
gardening, thus reducing municipal
water use
Rain Barrels
Definition. An artificial reservoir for storing
rainwater from residential or commercial
Purpose: To capture rainwater for private
use and reduce storm water runoff.
Construction Methods: Purchase and place
rain barrel at end of roof gutters.
Maintenance Activities: Minimal; occasional
cleaning of barrel.
Potential Drawbacks
Not recommended for human
consumption
Systems may require seasonal
maintenance
Requires insect control
Uncovered barrels pose threat for small
children and small animals
Other Considerations: This can generally be an encouraged practice through education rather than
regulation.
WS B
If
Benefits
Provides some water quality benefits
Reduces runoff volume from rooftops
Reduces energy costs for building
Reduced "heat island" effect in urban
areas
GrItt Roofs
Definition: Vegetated roof designed to
mitigate the effects of urbanization on water
Purpose: Reduce runoff and heat generated
by buildings.
Construction Methods: Roof must be
specifically designed and engineered to bear
the structural load of the plants and soil.
Maintenance Activities: Plant maintenance is
needed to establish the roof. Long -term
maintenance is contingent upon design but
should outlast conventional roofs by 20
years.
Potential Drawbacks
Structures must be constructed to
accommodate green roof
Construction is costly
Maintenance is higher than with
traditional roof
Other Considerations: A leak detection system is recommended as undetected leaks can be costly.
WS
L
F
y
A
3
Volume Reduction
II I
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutdnt
Removed
Annual Maintenance Cost
Key Excellent
1 Fair
0 Poor
Green Roofs
1
1
1
0
1
Low
High
High
Benefits
Provides some water quality benefits
Reduces runoff volume from rooftops
Reduces energy costs for building
Reduced "heat island" effect in urban
areas
GrItt Roofs
Definition: Vegetated roof designed to
mitigate the effects of urbanization on water
Purpose: Reduce runoff and heat generated
by buildings.
Construction Methods: Roof must be
specifically designed and engineered to bear
the structural load of the plants and soil.
Maintenance Activities: Plant maintenance is
needed to establish the roof. Long -term
maintenance is contingent upon design but
should outlast conventional roofs by 20
years.
Potential Drawbacks
Structures must be constructed to
accommodate green roof
Construction is costly
Maintenance is higher than with
traditional roof
Other Considerations: A leak detection system is recommended as undetected leaks can be costly.
WS
Benefits
Creates an aesthetically pleasing BMP
for ponds, infiltration areas, swales, etc.
Creates habitat in developed areas
Assists in reducing erosion
Reduces presence of invasive species
such as thistles, ragweed, and others
Vegetation Went
and Maintenance
Definition. Maintenance activities that are
needed to encourage desirable t growth
in buffers, along ponds, in avvaica, and in
infiltration areas.
Purpose: To establish desirable vegetation
within certain BMP's to provide habitat,
reduce erosion, and improve storm water
treatment.
Construction Methods: Seeding and
monitoring growth.
Considerations: Development of vegetation performance standards can be considered.
Potential Drawbacks
Requires annual maintenance
Cost and responsible party for
maintenance needs to be considered
Prescribed burning should be conducted
by trained professionals
Maintenance Activities: Annual inspection
and maintenance activities such as mowing,
prescribed burning, and spot treating with
herbicide are needed to establish and
maintain healthy, effective, and attractive
vegetated BMP's.
WS
&A suntan
Water Quality Treatment
Volume Reduction
Rate Control
Groundwater Recharge
Temperature Control
Land Requirements
Cost Per Pound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
Fair
0 Poor
Vegetation Establishment
and Maintenance
1
1
1
1
1
Low
Medium
Medium
Benefits
Creates an aesthetically pleasing BMP
for ponds, infiltration areas, swales, etc.
Creates habitat in developed areas
Assists in reducing erosion
Reduces presence of invasive species
such as thistles, ragweed, and others
Vegetation Went
and Maintenance
Definition. Maintenance activities that are
needed to encourage desirable t growth
in buffers, along ponds, in avvaica, and in
infiltration areas.
Purpose: To establish desirable vegetation
within certain BMP's to provide habitat,
reduce erosion, and improve storm water
treatment.
Construction Methods: Seeding and
monitoring growth.
Considerations: Development of vegetation performance standards can be considered.
Potential Drawbacks
Requires annual maintenance
Cost and responsible party for
maintenance needs to be considered
Prescribed burning should be conducted
by trained professionals
Maintenance Activities: Annual inspection
and maintenance activities such as mowing,
prescribed burning, and spot treating with
herbicide are needed to establish and
maintain healthy, effective, and attractive
vegetated BMP's.
WS
&A suntan
Figure 11-3
Conceptual Greenway Corridor Plan
CSAH 43/ Akron AGAR
Legend
Gi Candor
Benefits
Reduced size of storm water ponds
Reduced runoff volume through
reduction of Impervious surfaces
Ground water recharge potential
Reduced fuel and energy needs
Land Use Management
Definition: Manage land use in a ay that
will be most effective in treating storm water.
Purpose. Utilize techniques to age and
within the City to treat storm water runoff.
Examples:
Rural section streets
Building "up" and not "out"
Incorporate ponding into opens pace
and greenways
Methods:
Consideration through an AUAR type
process.
Get early "buy -in" from stakeholders.
Need to continuously evaluate successes
and challenges.
Potential Drawbacks
Less developable acreage
More dense development
Construction costs increases
Potential for increased inspection and
maintenance
S6
uality Treatment
me Reduction
ate Control
[water Recharge
rature Control
Requirements
>ound of Pollutant
Removed
Annual Maintenance Cost
Key: Excellent
1 Fair
0 Poor
Land Use Management
1
1
1
1
High
Site
Site
Dependent
Dependent
4
Iw
Figure 11-3
Conceptual Greenway Corridor Plan
CSAH 43/ Akron AGAR
Legend
Gi Candor
Benefits
Reduced size of storm water ponds
Reduced runoff volume through
reduction of Impervious surfaces
Ground water recharge potential
Reduced fuel and energy needs
Land Use Management
Definition: Manage land use in a ay that
will be most effective in treating storm water.
Purpose. Utilize techniques to age and
within the City to treat storm water runoff.
Examples:
Rural section streets
Building "up" and not "out"
Incorporate ponding into opens pace
and greenways
Methods:
Consideration through an AUAR type
process.
Get early "buy -in" from stakeholders.
Need to continuously evaluate successes
and challenges.
Potential Drawbacks
Less developable acreage
More dense development
Construction costs increases
Potential for increased inspection and
maintenance
S6
WATER QUALITY TRADING
ASSESSMENT HANDBOOK
am ENS tnwnlmes
_Mra411
Benefits
Can finance BMP's through "trading"
excess pollutant credits
Credits can also be purchased to meet
downstream TMDL load allocations (i.e.
Lake Pepin)
Buying and Selling Pollution
Load Credits
t, Definition: Trading pollution control
responsibility among sources.
Purpose: Reduce the overall cost of attaining
water quality goals by completing a transaction
between a pollutant buyer and seller.
Administrative Methods: If a treatment BMP has
been approved by agencies, the City could sell
credits or buy "outside" pollution control within
the City's major subwatershed.
Possible Application: The City implements
BMP's, such as the RESTORE Pond, and sells
pollution credits created by pond to upstream
polluters who cannot meet water quality
requirements.
Potential Drawbacks
Uncertainties due to no history of
successful market test in Minnesota
In states where markets have been
established the administrative processes
have been onerous
Other Considerations: The details of this type of system need to be worked out in cooperation with
the MPCA as part of the impaired waters program.
4
WS
Summary of
Alternative
Stormwater Management Techniques
WSL
Water Quality Treatment
uouanpag amntoA
[opuoD alga
a&egaay la4empunol5
lolluoD aanleaadway
sluamazmbaj purl
Cost Per Pound of Pollutant
Removed
Q
0
u
G
u
Fil
lsop aaueualuleyV lenuuv
Key: Excellent
1 Fair
O Poor
Comparison Relative to each BMP
Wet Ponds (NURP Ponds)
1
1
0
High
Low
Low
Infiltration Basin
High
Low
Medium
Ram Gardens
1
1
0
1
Low
High
High
RESTORE Pond
High
High
High
Dry Ponds
1
1
1
0
High
Low
Low
Sand Filters
1
1
1
1
High
High
High
Underground Storage
Systems
(No Infiltration
With Infiltration)
p/•
O/•
O/•
1/•
Low
High
High
Vegetated Swales
1
1
1
1
1
Medium
Low
Medium
In -Line Treatment Structures
1
0
0
0
0
Low
High
High
Comparison of BMP vs
Rural Street Curb Section
1
1
1
1
1
Low
Low
Low
Pavers and Green Parking
Lots
1
1
1
1
1
Low
High
High
Porous Pavement
1
1
1
1
1
Low
High
High
Ram Barrels
0
1
1
1
0
Low
Low
Low
Green Roofs
1
0
1
0
1
Low
High
High
Vegetation Establishment
and Maintenance
1
1
1
1
1
Low
Medium
Medium
Land Use Management
1
1
1
1
1
High
Site
Dependent
Site
Dependent
The rankings described on this page and on the fact sheets are meant for general
informational purposes only and are not meant to apply to any specific application.
Effectiveness of each practice will vary based on specific application, location, land
soils, and design.
use,
Anoem[ei