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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