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{{alert|This page is an edit and testing page use by the wiki authors.  It is not a content page for the Manual. Information on this page may not be accurate and should not be used as guidance in managing stormwater.|alert-danger}}
 
{{alert|This page is an edit and testing page use by the wiki authors.  It is not a content page for the Manual. Information on this page may not be accurate and should not be used as guidance in managing stormwater.|alert-danger}}
  
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[[Category:Level 1 - Best Management practices]]
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[[Category:Level 1 - Management]]
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[[Category:Level 1 - Pollutants]]
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[[Category:Level 1 - Regulatory]]
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[[Category:Level 2 - Best management practices/Credits]]
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[[Category:Level 2 - Best management practices/Design criteria]]
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[[Category:Level 2 - Best management practices/Permeable pavement]]
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[[Category:Level 2 - Pollutants/Phosphorus]]
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[[Category:Level 2 - Pollutants/Bacteria]]
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[[Category:Level 2 - Pollutants/Total suspended solids]]
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[[Category:Level 3 - Pollutants/Phosphorus/Phosphorus in runoff]]
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[[Category:Level 3 - Pollutants/Phosphorus/Managing phosphorus]]
  
<p dir="ltr" style="background-color:#d5fdf4; font-size:30px; text-align: center;" role="presentation" class="zfr3Q CDt4Ke"><span role="link" class="I4aHG"><span style="text-decoration:underline;" class="aw5Odc" data-ri="0" title="<a href=https://stormwater.pca.state.mn.us/index.php?title=Street_Sweeping_Phosphorus_Credit_Calculator_How-to-Guide donate"></span></span></p>
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[[Table of Contents test page]]
  
  
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Image:Stormwater BMPs.png|500px|thumb|alt=imagemap for stormwater BMPs|<font size=3>Stormwater Best Management Practices. Mouse hover over an '''i''' box to read a description of the practice, or click on an '''i''' box to go to a page on the practice.</font size>
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circle 30 125 30 [[Infiltration|Infiltration basins, infiltration trenches, dry wells, and underground infiltration systems capture and temporarily store stormwater before allowing it to infiltrate into the soil. As the stormwater penetrates the underlying soil, chemical, biological and physical processes remove pollutants and delay peak stormwater flows.]]
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circle 270 125 30 [[Bioretention|Bioretention (rain garden) is a terrestrial-based (up-land as opposed to wetland) water quality and water quantity control process. Bioretention employs a simplistic, site-integrated design that provides opportunity for runoff infiltration, filtration, storage, and water uptake by vegetation.]]
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circle 600 125 30 [[Trees|Tree trenches and tree boxes (collectively called tree BMP(s)), the most commonly implemented tree BMPs, can be incorporated anywhere in the stormwater treatment train but are most often located in upland areas of the treatment train. The strategic distribution of tree BMPs help control runoff close to the source where it is generated. Tree BMPs can mimic certain physical, chemical, and biological processes that occur in the natural environment.]]
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circle 690 150 30 [[Permeable pavement|Permeable pavements allow stormwater runoff to filter through surface voids into an underlying stone reservoir for temporary storage and/or infiltration. The most commonly used permeable pavement surfaces are pervious concrete, porous asphalt, and permeable interlocking concrete pavers (PICP). Permeable pavements have been used for areas with light traffic at commercial and residential sites to replace traditional impervious surfaces in low-speed roads, alleys, parking lots, driveways, sidewalks, plazas, and patios.]]
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circle 920 125 30 [[Stormwater and rainwater harvest and use/reuse|A stormwater harvesting and use system is a constructed system that captures and retains stormwater for beneficial use at a different time or place than when or where the stormwater was generated. A stormwater harvesting and use system potentially has four components: collection system (which could include the catchment area and stormwater infrastructure such as curb, gutters, and stormsewers), storage unit (such as a cistern or pond) treatment system: pre and post (that removes solids, pollutants and microorganisms, including any necessary control systems), if needed, and the distribution system (such as pumps, pipes, and control systems).]]
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circle 1130 125 30 [[Green roofs|Green roofs consist of a series of layers that create an environment suitable for plant growth without damaging the underlying roof system. Green roofs create green space for public benefit, energy efficiency, and stormwater retention/ detention. Green roofs occur at the beginning of stormwater treatment trains. Green roofs provide filtering of suspended solids and pollutants associated with those solids, although total suspended solid (TSS) concentrations from traditional roofs are generally low. Green roofs provide both volume and rate control, thus decreasing the stormwater volume being delivered to downstream Best Management Practices (BMPs).]]
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circle 30 325 30 [[Dry swale (Grass swale)|Dry swales, sometimes called grass swales, are similar to bioretention cells but are configured as shallow, linear channels. They typically have vegetative cover such as turf or native perennial grasses. Dry swales may be constructed as filtration or infiltration practices, depending on soils. If soils are highly permeable (A or B soils), runoff infiltrates into underlying soils. In less permeable soils, runoff is treated by engineered soil media and flows into an underdrain, which conveys treated runoff back to the conveyance system further downstream. Check dams incorporated into the swale design allow water to pool up and infiltrate into the underlying soil or engineered media, thus increasing the volume of water treated.]]
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circle 270 325 30 [[Wet swale (wetland channel)|Wet swales occur when the water table is located very close to the surface or water does not readily drain out of the swale. A wet swale acts as a very long and linear shallow biofiltration or linear wetland treatment system. Wet swales do not provide volume reduction and have limited treatment capability. Incorporation of check dams into the design allows treatment of a portion or all of the water quality volume within a series of cells created by the check dams. Wet swales planted with emergent wetland plant species provide improved pollutant removal. Wet swales may be used as pretreatment practices. Wet swales are commonly used for drainage areas less than 5 acres in size.]]
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circle 600 325 30 [[High-gradient stormwater step-pool swale|Stormwater step pools address higher energy flows due to more dramatic slopes than dry or wet swales. Using a series of pools, riffle grade control, native vegetation and a sand seepage filter bed, flow velocities are reduced, treated, and, where applicable, infiltrated. The physical characteristics of the stormwater step pools are similar to Rosgen A or B stream classification types, where “bedform occurs as a step/pool, cascading channel which often stores large amounts of sediment in the pools associated with debris dams”. Stormwater step pools are designed with a wide variety of native plant species depending on the hydraulic conditions and expected post-flow soil moisture at any given point within the stormwater step pool.]]
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circle 820 325 30 [[Vegetated filter strips|Vegetated filter strips are designed to remove solids from stormwater runoff. The vegetation can consist of natural and established vegetation communities and can range from turf grass to woody species with native grasses and shrubs. Because of the range of suitable vegetation communities, vegetated filter strips can be easily incorporated into landscaping plans; in doing so, they can accent adjacent natural areas or provide visual buffers within developed areas. They are best suited for treating runoff from roads, parking lots and roof downspouts. Their primary function is to slow runoff velocities and allow sediment in the runoff to settle or be filtered by the vegetation. By slowing runoff velocities, they help to attenuate flow and create a longer time of concentration. Filter strips do not significantly reduce runoff volume, but there are minor losses due to infiltration and depression storage. Filter strips are most effective if they receive sheet flow and the flow remains uniformly distributed across the filter strip.]]
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circle 1040 325 30 [[Iron enhanced sand filter (Minnesota Filter)|Iron-enhanced sand filters are filtration Best Management Practices (BMPs) that incorporate filtration media mixed with iron. The iron removes several dissolved constituents, including phosphate, from stormwater. Iron-enhanced sand filters may be particularly useful for achieving low phosphorus levels needed to improve nutrient impaired waters. Iron-enhanced sand filters could potentially include a wide range of filtration BMPs with the addition of iron; however, iron is not appropriate for all filtration practices due to the potential for iron loss or plugging in low oxygen or persistently inundated filtration practices.]]
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circle 1130 325 30 [[Filtration|Sand (media) filters have widespread applicability and are suitable for all land uses, as long as the contributing drainage areas are limited (e.g., typically less than 5 acres). Sand filters are not as aesthetically appealing as bioretention, which makes them more appropriate for commercial or light industrial land uses or in locations that will not receive significant public exposure. Sand filters are particularly well suited for sites with high percentages of impervious cover (e.g., greater than 50 percent). Sand filters can be installed underground to prevent the consumption of valuable land space (often an important retrofit or redevelopment consideration).]]
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circle 170 525 30 [[Stormwater ponds|Stormwater ponds are typically installed as an end-of-pipe BMP at the downstream end of the treatment train. Stormwater pond size and outflow regulation requirements can be significantly reduced with the use of additional upstream BMPs. However, due to their size and versatility, stormwater ponds are often the only management practice employed at a site and therefore must be designed to provide adequate water quality and water quantity treatment for all regulated storms.]]
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circle 265 525 30 [[Stormwater wetlands|Stormwater wetlands are similar in design to stormwater ponds and mainly differ by their variety of water depths and associated vegetative complex. They require slightly more surface area than stormwater ponds for the same contributing drainage area. Stormwater wetlands are constructed stormwater management practices, not natural wetlands. Like ponds, they can contain a permanent pool and temporary storage for water quality control and runoff quantity control. Wetlands are widely applicable stormwater treatment practices that provide both water quality treatment and water quantity control. Stormwater wetlands are best suited for drainage areas of at least 10 acres. When designed and maintained properly, stormwater wetlands can be an important aesthetic feature of a site.]]
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circle 600 525 30 [[Pretreatment|Pretreatment practices are installed immediately preceding one or more structural stormwater BMPs. Pretreatment reduces maintenance and prolongs the lifespan of structural stormwater BMPs by removing trash, debris, organic materials, coarse sediments, and associated pollutants prior to entering structural stormwater BMPs. Implementing pretreatment devices also improves aesthetics by capturing debris in focused or hidden areas.]]
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circle 820 510 30 [[Sediment control practices|Sediment control practices are designed to prevent or minimize loss of eroded soil at a site. Typical sediment control practices focus on 1) physical filtration of sediment by trapping soil particles as water passes through a silt fence, drop inlet screen, fiber roll, etc., 2)settling processes, that allow sediment to fall out of flows that are slowed and temporarily impounded in ponds, traps, or in small pools created by berms, silt fencing, inlet protection dikes, check dams, etc.]]
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circle 1040 500 30 [[Erosion prevention practices|Erosion prevention practices include 1) planning approaches that minimize the size of the bare soil area and the length of time disturbed areas are exposed to the elements – especially for long, steep slopes and easily erodible soils, 2) diverting or otherwise controlling the location and volume of run-on flows to the site from adjacent areas, 3)keeping concentrated flows in ditches stabilized with vegetation, rock, or other material, and 4)covering bare soil with vegetation, mulch, erosion control blankets, turf reinforcement mats, gravel, rock, plastic sheeting, soil binder chemicals, etc.]]
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circle 1235 525 30 [[Pollution prevention|Pollution prevention (P2) is a “front-end” method to decrease costs, risks, and environmental concerns. In contrast to managing pollution after it is created, P2 reduces or eliminates waste and pollution at its source. P2 includes a variety of residential, municipal, and industrial practices.]]
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Image:Updated MPCA_Small_Site_Graphic.JPG|Image map test
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circle 55 152 15 [[Protection of existing trees on construction sites]]
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circle 55 291 15 [[Construction stormwater best management practice - stockpile management|Stockpile management]]
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circle 55 378 15 [[Construction stormwater best management practice - construction materials management requirements|Construction materials management]]
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circle 55 447 15 [[Construction stormwater best management practice - construction materials management requirements|Construction materials management]]
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circle 55 564 15 [[Sediment control practices - Perimeter controls for disturbed areas]]
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circle 55 714 15 [[Sediment control practices - Storm drain inlet protection]]
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circle 55 813 15 [[Construction stormwater best management practice – Concrete, paint, stucco and other washout guidance]]
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circle 383 817 15 [[Sediment control practices - Vehicle tracking BMPs]]
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circle 388 527 18 [[Protection of existing trees on construction sites]]
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circle 395 634 18 [[Sediment control practices - Storm drain inlet protection]]
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circle 545 579 18 [[Construction stormwater best management practice – Concrete, paint, stucco and other washout guidance]]
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circle 624 433 18 [[Construction stormwater best management practice - construction materials management requirements|Construction materials management]]
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circle 667 753 18 [[Sediment control practices - Vehicle tracking BMPs]]
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circle 784 677 18 [[Construction stormwater best management practice – Stormwater Pollution Prevention Plan]]
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circle 838 805 15 [[Sediment control practices - Perimeter controls for disturbed areas]]
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circle 939 358 18 [[Construction stormwater best management practice - construction materials management requirements|Construction materials management]]
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circle 1004 421 18 [[Construction stormwater best management practice - stockpile management|Stockpile Management]]
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circle 1035 660 15 [[Protection of existing trees on construction sites]]
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circle 1110 136 15 [[Construction stormwater best management practice – Stormwater Pollution Prevention Plan]]
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circle 1182 557 15 [[Construction stormwater best management practice – Site stabilization]]
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circle 1132 711 15 [[Construction stormwater best management practice – Site stabilization]]
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circle 1297 450 18 [[Protection of existing trees on construction sites]]
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rect 449 170 507 185 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_5_Stormwater_Pollution_Prevention_Plan_(SWPPP)_Content#5.24 The SWPPP must describe methods to minimize soil compaction and preserve topsoil. Minimizing soil compaction is not required where the function of a specific area dictates compaction.]
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rect 409 327 459 342 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_8_Erosion_Prevention_Practices#8.4 Permittees must stabilize all exposed soil areas, including stockpiles. Stabilization must be initiated immediately to limit soil erosion when construction activity has ceased on any portion of the site and will not resume for a period exceeding 14 calendar days. Stabilization must be completed no later than 14 calendar days after the construction activity has ceased. Stabilization is not required on certain temporary stockpiles but must provide sediment controls at the base of the stockpile.]
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rect 310 397 368 412 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_12_Pollution_Prevention_Management_Measures#12.2 Permittees must place building products and landscape materials under cover (e.g., plastic sheeting or temporary roofs) or protect them by similarly effective means designed to minimize contact with stormwater. Permittees are not required to cover or protect products which are either not a source of contamination to stormwater or are designed to be exposed to stormwater.]
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rect 107 514 165 529 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_12_Pollution_Prevention_Management_Measures#12.5 Permittees must properly store, collect and dispose solid waste in compliance with Minn. R. ch. 7035.]
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rect 258 665 308 680 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_9_Sediment_Control_Practices#9.2 Permittees must establish sediment control BMPs on all downgradient perimeters of the site and downgradient areas of the site that drain to any surface water, including curb and gutter systems. Permittees must locate sediment control practices upgradient of any buffer zones. Permittees must install sediment control practices before any upgradient land-disturbing activities begin and must keep the sediment control practices in place until they establish permanent cover.]
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rect 243 765 293 780 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_9_Sediment_Control_Practices#9.7 Permittees must protect all storm drain inlets using appropriate BMPs during construction until they establish permanent cover on all areas with potential for discharging to the inlet.]
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rect 39 882 98 896 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_12_Pollution_Prevention_Management_Measures#12.9 Permittees must provide effective containment for all liquid and solid wastes generated by washout operations related to the construction activity. Permittees must prevent liquid and solid washout wastes from contacting the ground and must design the containment so it does not result in runoff from the washout operations or areas. ermittees must properly dispose liquid and solid wastes in compliance with MPCA rules. Permittees must install a sign indicating the location of the washout facility.]
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rect 447 900 506 914 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_9_Sediment_Control_Practices#9.11 Permittees must install a vehicle tracking BMP to minimize the track out of sediment from the construction site or onto paved roads within the site.]
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rect 1254 237 1309 252 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_20_SWPPP_Availability Permittees must keep the SWPPP, including all changes to it, and inspections and maintenance records at the site during normal working hours by permittees who have operational control of that portion of the site.]
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rect 1218 797 1268 812 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_8_Erosion_Prevention_Practices#8.4 Permittees must stabilize all exposed soil areas, including stockpiles. Stabilization must be initiated immediately to limit soil erosion when construction activity has permanently or temporarily ceased on any portion of the site and will not resume for a period exceeding 14 calendar days. Stabilization must be completed no later than 14 calendar days after the construction activity has ceased. Stabilization is not required on constructed base components of roads, parking lots and similar surfaces.]
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rect 1209 863 1268 878 [https://stormwater.pca.state.mn.us/index.php?title=MN_CSW_Permit_Section_23_Discharges_to_Special_(Prohibited,_Restricted,_Other)_and_Impaired_Waters#23.9 Permittees must immediately initiate stabilization of exposed soil areas, as described in item 8.4, and complete the stabilization within seven (7) calendar days after the construction activity in that portion of the site temporarily or permanently ceases.]
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'''Information'''
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<div class="mw-collapsible-content">'''
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*[https://stormwater.pca.state.mn.us/index.php?title=Information_on_soil Information on soil]
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*[[Compost and stormwater management]]'''</div>
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<font size=5>Reporting phosphorus and TSS reduction credits from street sweeping</font size>
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[[File:Selbig graph.png|400px|thumb|alt=graph of P removal with street sweeping|<font size=3>Research conducted by Bill Selbig (USGS) shows that streets, when cleaned of leaf litter prior to a storm, can significantly decrease phosphorus loads in stormwater runoff ([https://www.usgs.gov/centers/umid-water/science/using-leaf-collection-and-street-cleaning-reduce-nutrients-urban?qt-science_center_objects=0#qt-science_center_objects Link to study])</font size>]]
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At this time, the MPCA has not developed guidance for how to credit reductions in phosphorus or total suspended solid loading associated with enhanced street sweeping. We anticipate developing this guidance in 2022. In developing  this guidance, consider the following.
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*Baseline: Credits toward permit compliance, such as compliance with <span title="The amount of a pollutant from both point and nonpoint sources that a waterbody can receive and still meet water quality standards"> [https://stormwater.pca.state.mn.us/index.php?title=Total_Maximum_Daily_Loads_(TMDLs) '''total maximum daily loads''']</span>, can only be applied toward enhanced street sweeping. This is sweeping that results in pollutant reductions above pollutant reductions associated with sweeping that occurred at the <span title="The year from which stormwater practices can be credited toward meeting a total maximum daily load (TMDL) wasteload allocation (WLA)"> '''[https://stormwater.pca.state.mn.us/index.php?title=Baseline_year baseline year]'''</span>.
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*Accounting for seasonality: The image on the right illustrates the seasonal nature of phosphorus loading in areas where leaves and other organic sources are a source of phosphorus. Most models and other methods of estimating annual loads do not consider this seasonality and most likely significantly underestimates annual phosphorus loading. Accurate representation of impacts from enhanced street sweeping will require adjusting initial (baseline) calculations of loading. The MPCA is discussing appropriate methods for accounting for this seasonality.
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*Downstream BMPs: Enhanced street sweeping potentially impacts loading to and performance of downstream BMPs. The MPCA is discussing if adjustments in downstream loading and/or adjustments in BMP performance are needed to accurately determine changes in phosphorus loading in areas where enhanced street sweeping is implemented.
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[[Ecosystem Function of vegetation in stormwater management]]
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==Habitat==
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===Pollinators & Insects===
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===Reptiles===
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==Nutrient Cycling==
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===Primary Producers===
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===Terrestrial Food Chain===
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===Aquatic Food Chain===
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==Soil Regeneration==
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<p dir="ltr" style="background-color:#d5fdf4; font-size:30px; text-align: center;" role="presentation" class="zfr3Q CDt4Ke">
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<a href="https://stormwater.pca.state.mn.us/index.php?title=Street_Sweeping_Phosphorus_Credit_Calculator_How-to-Guide">
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Donate
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</p>
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<p dir="ltr" style="background-color:#d5fdf4; font-size:30px; text-align: center;" role="presentation" class="zfr3Q CDt4Ke">
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<a href="https://stormwater.pca.state.mn.us/index.php?title=Street_Sweeping_Phosphorus_Credit_Calculator_How-to-Guide">
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<span role="link" class="I4aHG">
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<span style="text-decoration:underline;" class="aw5Odc" data-ri="0">Donate
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</span>
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</span>
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</a>
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This page provides recommendations for managing and storing snow collected from impervious surfaces. The recommendations focus on protection of surface waters (lakes, rivers, wetlands), except where otherwise noted.
 
 
'''NOTE''': This page only provides a general overview of snowmelt dynamics, instead focusing on snow storage. Numerous references are included throughout this page and the reader is referred to those for more detailed information. This manual also has a page on [[Cold climate impact on runoff management]] which provides a comprehensive discussion of cold climate considerations for managing urban stormwater and stormwater practices, including information on snowmelt runoff and snow management.
 
 
==Dynamics of snowpack melt==
 
Snow packs experience multiple freeze-thaw cycles through the winter and early spring. This results in partial melting and channelization of meltwater in the snowpack. Soluble pollutants are preferentially transported with this meltwater and accumulate near the base of the snowpack, while particulates are filtered during these partial melts. This accounts for the high release of soluble pollutants in the early phases of the melt.
 
  
Oberts (2010) described a three stage melt process in urban areas.
 
*The first melt stage involves melting from paved areas. If this snow and ice contains deicers, the resulting meltwater is very saline water and also carries accumulated road pollutants into drainage systems and local receiving waters. If snow from these paved areas is collected and moved to a storage location, meltwater from these storage piles may contain high levels of soluble pollutants such as chloride, phosphorus, and some metals, as well as elevated biochemical oxygen demand.
 
*The second melt stage involves the gradual melt of snow piles adjacent to road surfaces. This melt is similar to initial melting in stored snow piles, where initial chemical concentrations of soluble pollutants is relatively high, while sediment-bound pollutant concentrations are low.
 
*The final stage of the snowmelt is the melt of pervious areas, such as grassed lawns. Chemical concentrations are typically lower but may be dominated by sediment and sediment-bound pollutants if the melt occurs quickly, as would occur with warm temperatures and/or rain falling on the snowpack.
 
  
{{:Characteristics of snowmelt}}
 
 
==Water quality and chemistry of snow and snowmelt runoff==
 
The quality of runoff from melted snow is affected by the dynamics of snowmelt. The following information was extracted from the literature.
 
*Initial meltwater is acidic and contains a higher percentage of soluble pollutants compared to later meltwater. The initial melt may comprise only 30% of the total volume but contain 60-90% of the total phosphorus and nitrogen released from the entire melt. Johannessen and Henriksen (1978) found in both laboratory and field studies that about 40 to 80% of 16 pollutants were released from experimental snowpacks with the first 30% of the liquid melt. Pollutant concentrations in the initial melt are typically 2 to 2.5 times greater than those in the remaining snowpack.
 
*Street loads of sediment and toxic materials are at an annual peak at the onset of winter melt and early spring rainfalls.
 
*The last period of melting contains lower concentrations of pollutants and is dominated by particulates and associated pollutants.
 
 
Water quality of snowmelt differs from non-winter runoff.
 
*Data from Capital Region Watershed District (CRWD) indicates total phosphorus concentrations are similar (medians of 0.325 and 0.304 mg/L for snowmelt and non-snowmelt runoff, respectively), but concentrations are more variable in winter runoff (mean concentrations of 0.412 and 0.289 mg/L, respectively).
 
*CRWD data shows higher concentrations of dissolved phosphorus in snowmelt compared to non-winter runoff (0.119 and 0.053 mg/L, respectively). Thus, dissolved phosphorus comprises about 35% of total phosphorus in snowmelt but only about 20% of total phosphorus in non-winter runoff.
 
 
'''Recommended references'''
 
*Bratt, Anika R., Jacques C. Finlay, Sarah E. Hobbie, Benjamin D. Janke, Adam C. Worm, and Kathrine L. Kemmitt. 2017. Contribution of Leaf Litter to Nutrient Export during Winter Months in an Urban Residential Watershed Environ Sci Technol 51(6):3138-3147. doi: 10.1021/acs.est.6b06299.
 
*Oberts, Gary L. 2000. Influence of Snowmelt Dynamics on Stormwater Runoff Quality. Metropolitan Council, St. Paul, MN. Watershed Protection Techniques. 1(2): 55-61
 
 
==Recommendations for snow storage==
 
This section provides guidance and recommendations for identifying appropriate snow storage areas, storing snow in those areas, and operations and maintenance of snow storage areas.
 
 
===Siting recommendations===
 
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<table class="infobox" style="border:3px; border-style:solid; border-color:#FF0000; text-align: right; width: 450px; font-size: 100%">
 
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<th><center><font size=3>'''Methods for identifying baseflow contribution'''</font size></center></th>
 
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<td>
 
*Consult local groundwater maps and/or reports if they are available. Examples include [https://www.dnr.state.mn.us/waters/groundwater_section/mapping/status.html county geologic atlases] and hydrologic maps produced by the Unites States Geological Survey. Although these maps typically provide information at a watershed or regional level, they can generally be used to identify the importance of baseflow to major receiving waters, though they cannot typically be used to quantify baseflow.
 
*Compare water table (groundwater) elevations to surface water elevations on topographic maps. This method is relatively easy to use if groundwater elevation data exists, but it is subject to inaccuracies as water levels fluctuate and cannot be used to quantify baseflow.
 
*Utilize existing reports from local studies. Examples include using information from remediation studies. These reports are reasonably accurate if the study was conducted near the receiving water but cannot be used to quantify baseflow.
 
*Baseflow separation methods are accurate but data intensive unless monitoring data exist for the receiving water. [https://www.youtube.com/watch?v=w7E0B7MVZXs Link here for a video on computing baseflow using baseflow separation.] These methods can be used to quantify baseflow contributions.
 
*Solutes and tracers can be used to identify the occurrence of baseflow, but are difficult to use when quantifying baseflow.
 
*Water balance methods can be used if adequate climatological data exist. These methods can be used to quantify baseflow.
 
*Models can be used but are typically data intensive. Modeling can be used to quantify baseflow.
 
For more information, see [https://d1wqtxts1xzle7.cloudfront.net/50777458/j.1752-1688.1999.tb03599.x20161207-15697-mvzei8-with-cover-page-v2.pdf?Expires=1635451433&Signature=VaAljDv~sR3LJbGJP0tcoq1yqhiu9BeirvTBcx2Bi-~2GldRWVUiPgP93KakHu1s9AGRoIrurBvlI2wZ5ih22NA9DZrN0lxjBK1OhF2u4D6RN9dGdAmnDHaFL48S60WVjVQsA5lI3D6CY1MzZO4E~yjDZ57OAN5X8OLpcGaxd~iIhXg7vK~O3TnCgTHWAp43DwkDQeedoCJtMqBNKz4X2F9T5mhAKnVoyJsj6vuSq5MkTMMq4MIQN8bA6AQ1a9VjXIK36YDZszkTA0tEmKV70fwub4kYw2wUA2XSDaoe65TB4sqdfuDudVjN8aXt-LFKekjwH6W~k1T1vfhqbjCVag__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA], [https://hess.copernicus.org/articles/19/2587/2015/hess-19-2587-2015.pdf], [https://www.hec.usace.army.mil/confluence/hmsdocs/hmsum/4.8/subbasin-elements/selecting-a-baseflow-method], [https://pubs.usgs.gov/sir/2012/5034/sir2012-5034.pdf], [https://water.usgs.gov/watercensus/file/Miller-et-al-2015.pdf], [https://www.tandfonline.com/doi/pdf/10.1623/hysj.2005.50.5.911], [https://www.ijstr.org/final-print/july2017/Comparative-Analysis-Of-Methods-Of-Baseflow-Separation-Of-Otamiri-Catchment.pdf].
 
</td>
 
</tr>
 
</table>
 
</div>
 
 
*Identify receiving waters and assess the risk to them. Although identifying the contribution of baseflow to receiving  waters can be challenging, it is important if meltwater will infiltrate and recharge groundwater. Potential receiving waters include the following.
 
**Streams and rivers with a significant baseflow component
 
**Streams and rivers with low baseflow component
 
**Lakes and wetlands with a baseflow component
 
**Lakes and wetlands with limited baseflow
 
**Groundwater
 
*Consult with your local community or municipality for technical guidelines on snow site management and operations.
 
*Estimate how much snow disposal capacity is needed for the season so that an adequate number of disposal sites can be selected and prepared. Plan on snow storage capacity equal to 20-30 percent of the snow volume from the source area.
 
*Determine potential pollutants of concern from the snow source areas
 
*Considering potential pollutants of concern, when practicable, designate snow storage areas in locations that enable runoff to be directed to stormwater BMPs for treatment prior to discharge to a receiving water, including groundwater.
 
 
{| class="wikitable"
 
|-
 
| colspan="8" style="text-align: center;"| '''Pollutants of concern for different land uses'''
 
|-
 
! Land use !! Sediment !! Phosphorus !! Nitrogen !! Metals !! Organics !! Chloride !! BOD
 
|-
 
| Residential ||  || X || X ||  ||  ||  || X
 
|-
 
| Commercial || X ||  ||  || X ||  || X ||
 
|-
 
| Industrial || X ||  ||  || X || X || X ||
 
|-
 
| Transportation || X ||  ||  || X || X || X ||
 
|-
 
| Park ||  || X || X ||  ||  ||  || X
 
|-
 
| Parking lot ||  ||  ||  || X ||  || X ||
 
|}
 
 
*Snow storage should be avoided in the following situations.
 
**Within a floodplain
 
**Within 100 feet of active karst or areas where fractured bedrock is within 50 feet of the land surface
 
**Within setback distances from receiving waters
 
**On permeable soils (Hydrologic Soil Group A) where infiltration is not recommended or is prohibited under the Minnesota Construction Stormwater General Permit
 
**In sanitary landfills, quarries, and gravel pits
 
**In sections of parks or playgrounds that will be used for direct contact recreation after the snow season
 
**In a receiving water (e.g. lake, river, wetland)
 
*Prioritize potential sites based on the following selection criteria.
 
**Upland sites are preferred
 
**Slopes should be less than 6 percent, with slopes less than 2 percent preferred
 
**Site that can be used indefinitely are preferred, particularly if the site can be engineered to minimize environmental impacts
 
**Preference is for storage on permeable material that meets typical stormwater design standards found in the Minnesota Stormwater Manual (e.g. 3 feet separation to seasonal high water table)
 
 
===Site recommendations===
 
*Storage
 
**Snow should not be stored in stormwater treatment BMPs.
 
**Snow may be stored above a vegetated filter strip
 
**Do not locate snow storage areas on top of drain inlets.
 
**Where applicable, locate storage areas outside of jurisdictional snow storage ROWs (usually 15-20 feet off of roadway).
 
**Avoid siting snow storage on compacted or poorly draining soils (D soils), unless the meltwater is diverted to a treatment BMP that can treat the water quality volume.
 
**For snow that may contain elevated levels of pollutants (e.g., commercial parking lots or roads), site snow storage on an impervious surface that drains to a stormwater treatment BMP.
 
**Employ concave landscaped areas rather than mounded landscapes for snow storage.
 
**Locate snow storage areas to maximize solar exposure and away from primary roadways to the greatest extent feasible
 
*Site
 
**Clearly identify the boundaries of the snow storage area to be visible under winter conditions.
 
**When storing snow in close proximity to sensitive receiving waters, construct a berm around the perimeter of the snow storage area to contain the snowmelt or construct a vegetated filter strip between the receiving water and the snow storage area.
 
**When storing snow in landscaped areas, plant with native and adapted species tolerant of snow storage (perennials that die back annually and shrubs/trees that can bend with weight, but not break).
 
**For unpaved snow storage areas where snowplowing equipment will operate, the snow storage area should be covered with gravel or plowed to maintain 12 inches of packed snow to reduce soil disturbance and soil compaction.
 
**Snow storage areas should be maintained to reduce erosion and to ensure easy removal of accumulated pollutants or sediments such as sand, road dirt, trash and salts.
 
**A silt fence, earthen berm or equivalent barrier should be placed securely on the downgradient side of the snow disposal site. These types of structures can be used to direct meltwater and surface runoff to settling ponds or detention basins and to minimize the possible seepage of contaminants into groundwater. If earthen berms or channels are used to contain or direct the flow of melt water they should be stabilized to prevent soil erosion during high flows.
 
**Plant stockpile areas with salt-tolerant ground cover species
 
*Meltwater
 
**When feasible, route meltwater to an appropriate stormwater treatment BMP. This is highly recommended if downstream receiving waters are sensitive to or impaired for pollutants of concern in the stored snow.
 
**Provide appropriate pretreatment when routing meltwater to a downstream BMP. This may be achieved within the storage area if the storage area provides adequate storage volume to trap sediment left behind by melting snow
 
**Meltwater should cross a gravel or erosion resistant buffer zone between the filter berm and surface water.
 
**Sites which do not drain to treatment BMP should be contained by a snow fence, filter berm, small detention basin and buffer zone ( between the filter berm and storm sewer). An example of such a site might be a gravel parking lot which has sewer drainage.
 
 
===Inspection and maintenance===
 
*Before and after winter, clean the designated snow storage area of accumulated sand, trash, and debris, and inspect any associated drainage outlets or conveyance facilities for damage or erosion.
 
*Before and after winter, repair any damage or erosion that may have occurred to the snow storage area from snow removal equipment or other snow storage activities.
 
*Restore the soil if needed. Regrade if channelization from snowmelt or flowing water has occurred. Reseed with appropriate vegetation.
 
*Assess and if necessary, rehabilitate the infiltration capacity of the storage area and confirm conveyance facilities are functional.
 
*Monitor the quality of snowmelt
 
 
===References for snow disposal and storage===
 
*Alaska Department of Environmental Conservation, Division of Water. [https://dec.alaska.gov/water/wastewater/stormwater/snow-disposal/snow-disposal-guidance/ Snow Disposal Site Selection Guidance]
 
*Carlson, Robert F., David L. Barns, Nathanael Vaughan, Anna Forsstrom. 2003. [http://www.dot.state.ak.us/stwddes/research/assets/pdf/fhwa_ak_rd_03_04.pdf Synthesis of Best Management Practices for Snow Storage Areas]. University of Alaska, Fairbanks. Department of Civil and Environmental Engineering. Alaska Department of Transportation and Public Facilities Research & Technology Transfer. FHWA-AK-RD-03-04. September.
 
*Lake Tahoe Stormwater Management Program. 2014. [https://tahoebmp.org/bmphandbook.aspx?AspxAutoDetectCookieSupport=1 Snow Storage]. Chapter 4-2c.
 
*Massachusetts Department of Environmental Protection Bureau of Water Resources. 2020. [https://www.mass.gov/doc/2020-snow-disposal-policy-and-guidance/download Snow Disposal Guidance].
 
*Municipality of Anchorage. 2017. [http://anchoragestormwater.com/ Management and Design Criteria Manual]. Volume 1, Chapter 8.
 
*Pace Partners. [https://www.pacepartners.com/wp-content/uploads/2018/06/salt-storage-and-snow-disposal-bmps-1.pdf Stormwater Best Management Practices Salt, Sand and Deicer Storage & Snow Disposal].
 
*Reinosdotter, K. 2007. [https://www.diva-portal.org/smash/get/diva2:998901/FULLTEXT01.pdf Sustainable Snow Handling]. Doctoral Thesis. Luleå University of Technology.
 
*Urban Drainage and Flood Control District. 2010. [https://mhfd.org/wp-content/uploads/2019/12/S-10-Snow-and-Ice-Management.pdf Snow and Ice Management]. Urban Storm Drainage Criteria Manual Volume 3.
 
*Wheaton, S.R. and W.J. Rice, 2003. [http://anchoragestormwater.com/Documents/siting_design_ops_snowdisp_sites.pdf Siting, design and operational controls for snow disposal sites]. In Proceedings - Urban Drainage and Highway Runoff in Cold Climate, March 25-27, 2003, Riksgränsen, Sweden, pp.85-95.
 
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Revision as of 17:11, 1 July 2022

Warning: This page is an edit and testing page use by the wiki authors. It is not a content page for the Manual. Information on this page may not be accurate and should not be used as guidance in managing stormwater.

Table of Contents test page


Reporting phosphorus and TSS reduction credits from street sweeping

graph of P removal with street sweeping
Research conducted by Bill Selbig (USGS) shows that streets, when cleaned of leaf litter prior to a storm, can significantly decrease phosphorus loads in stormwater runoff (Link to study)

At this time, the MPCA has not developed guidance for how to credit reductions in phosphorus or total suspended solid loading associated with enhanced street sweeping. We anticipate developing this guidance in 2022. In developing this guidance, consider the following.

  • Baseline: Credits toward permit compliance, such as compliance with total maximum daily loads, can only be applied toward enhanced street sweeping. This is sweeping that results in pollutant reductions above pollutant reductions associated with sweeping that occurred at the baseline year.
  • Accounting for seasonality: The image on the right illustrates the seasonal nature of phosphorus loading in areas where leaves and other organic sources are a source of phosphorus. Most models and other methods of estimating annual loads do not consider this seasonality and most likely significantly underestimates annual phosphorus loading. Accurate representation of impacts from enhanced street sweeping will require adjusting initial (baseline) calculations of loading. The MPCA is discussing appropriate methods for accounting for this seasonality.
  • Downstream BMPs: Enhanced street sweeping potentially impacts loading to and performance of downstream BMPs. The MPCA is discussing if adjustments in downstream loading and/or adjustments in BMP performance are needed to accurately determine changes in phosphorus loading in areas where enhanced street sweeping is implemented.