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Minnesota Stormwater Manual

Composition, characterization, and management of street sweepings
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Street sweepings are materials such as sand, salt, leaves and debris removed from city streets, parking lots and sidewalks to prevent these materials from being washed into storm sewers and surface waters, and to improve the appearance of public roadways. For a discussion of potential benefits associated with street sweeping, see Overview, water quality benefits, and other co-benefits of street sweeping.

To see references for material on this page, link here.

Sources of materials in street sweepings

The primary sources of materials in street sweepings include the following.

  • Automobiles and other vehicles. These are important sources of hydrocarbons associated with fluids (e.g. oil, gasoline, antifreeze) and metals associated with vehicle parts (e.g. brake linings, tire wear). These materials, particularly metals, are typically released at higher rates as vehicle speed increases and as the extent of stopping increases.
  • Vegetation. Trees and grass adjacent to impermeable surfaces are important sources of organic materials to impervious surfaces that are swept. These organic materials are important sources of phosphorus and nitrogen, may contribute to oxygen demand, and may act as source areas for bacteria.
  • Atmospheric deposition. Deposition is an important source of inorganic solids. This includes deposition from near-source and distant-source areas. These solids may be important sources of pollutants attached to the solids, including metals, PAHs, and a range of emerging chemicals (e.g. pesticides, microplastics).
  • Local sources. This includes a wide range of sources that may have significant impacts locally. Examples include active construction sites (sources of sediment), industry (sources of organics), and contaminated sites (e.g. salvage yards, vehicle operations facilities, waste management facilities).
  • Trash and debris. With streets that are frequently swept, trash is typically not an important source of pollutants. However, in some areas where inputs of these are high, or where sweeping is infrequent, thus allowing the materials to break down, trash and debris can be important contributors of certain pollutants, such as microplastics.
  • Exposed and poorly managed soils. Soil, when exposed, poorly managed, or on steep slopes, can be an important source of sediment. Unless the soil is associated with another source (e.g. metals in high transportation areas), eroded soil transported to impervious surfaces is not an important source of other pollutants.
  • Irrigated lawns. Lawns that are over-watered can be important sources of bacteria, organic material, and phosphorus if the source water contains polyphosphates.
  • De-icing materials and sand applied for traction. In cold climates, de-icing materials are important sources of chloride, sodium, and phosphorus. Sand applied for traction is an important source of sediment.

Composition and characteristics of street sweeping materials

The composition and characteristics of street sweepings depends on multiple factors, including but not limited to the following. The discussion describes typical conditions.

  • Source area (land use). Concentrations of metals, PAHs, and other organics, including many emerging chemicals, are higher in medium and high intensity developed land uses, such as industrial, heavy commercial, and high transportation areas, compared to lower intensity developed areas, such as residential areas. Sources of nutrients associated with organic material are greatest in residential areas.
  • Type of sweeper.
  • Time of year.
  • Buildup period/interval.
  • Soil. An important factor affecting the occurrence and distribution of pollutants in sweeping material is particle size. Concentrations of metals and organics that bind with inorganic sediment increase as particle size decreases. Thus, soil can locally play an important role in the composition of material accumulating on impervious surfaces, particularly when soils are exposed (e.g. active construction sites) or poorly managed (e.g. compacted or exposed soils, or soils on steep slopes).

Concentrations of potential pollutants in sweeping material

We conducted a limited literature review of chemical data for street sweepings. The data are summarized in the adjacent table.

Metal concentrations are below Tier 1 Soil Reference Values (SRV), with only lead (25%), arsenic (35.6%), and cadmium (50.8%) median concentrations being 25 percent or more of the SRV. Maximum concentrations of lead and arsenic exceeded the Tier 1 SRV in one study each. Median metal concentrations were below the soil leaching value (SLV), with maximum arsenic concentration exceeding the SLV in one study. Generally, concentrations of metals in street sweepings are not significantly different from concentrations in green wastes and green/food composts.

We found limited datasets containing information for organic chemicals, but there are several studies where organics were sampled and results described in the paper (Obrien, 2014; Lloyd et al., 2018; Miller et al., 2016; Sutherland et al., 2012; Walch, 2006). In general, diesel range organic (DRO) and total petroleum hydrocarbon (TPH) concentrations are elevated in street sweepings. Proper composting results in degradation of these compounds below levels of concern. Polycyclic Aromatic Hydrocarbons (PAHs) are elevated in street sweepings, with occasional exceedance of Tier 1 SRVs for PAH equivalents. Composting will not effectively lead to degradation of middle- and heavy-molecular weight PAHs.

Storing, screening, using, and disposing sweeping material

There is limited guidance in the literature on management of street sweepings. This page summarizes information found in the literature and may be useful as guidance for managing sweepings.

Storage

  • Storage should be
    • at the site where the sweepings are generated (e.g. at a parking area that was swept);
    • at a location, such as a Department of Public Works (DPW) yard, that is under the control of the governmental entity doing the sweeping or has contracted for the sweeping; or,
    • at other locations with prior written approval from the local governing authority.
  • Street Sweepings should be protected from wind and rain to the extent necessary to prevent dust, erosion, and off-site migration.
  • Street Sweepings should not be stored within the 100 foot buffer zone of a wetland or within wetland resource areas including bordering vegetative wetlands and riverfront areas.
  • Street Sweepings should not be stored within 500 feet of a ground or surface drinking water supply.
  • Storage of the Street Sweepings should incorporate good management practice and result in no public nuisance.
  • Street Sweepings should be used within one year of collection.

References

Screening street sweepings

Three waste streams are generated during the screening phase - solid waste, organic debris, and sediment.

Solid waste, such as paper, auto parts and other trash, should be removed from all street sweepings prior to use. Solid waste screened from the street sweepings should be disposed of at a permitted solid waste facility. Leaves, twigs and other organic matter should also be removed when good engineering practice indicates this is necessary to produce a material that is suitable for the intended use. The organic material may be composted. If the compost is to be reused, ensure it has been properly cured or aged. This ensures the removal of pathogens and degradation of light and medium molecular weight organic compounds. For guidance on compost maturity, including links to guidelines for composting, link here.

A 3/4-inch mesh will screen out much of the debris from collected street sweepings prior to mixing. If a municipality chooses to rinse the sweepings to remove the fine particles and debris so that the sand may be reused on roads during the following winter, contact local authorities for additional guidance and discharge requirements.

Screened materials should be stored following the guidelines described above.

Using and disposing sweepings

A fact sheet by the Minnesota Pollution Control Agency outlines management options for reuse of street sweepings. Much of the discussion in this section comes from this fact sheet. Note this fact sheet was last updated in 2010.

Street sweepings are not considered hazardous material and do not require testing, but they are not suitable for unrestricted use, even after screening. Sweepings cannot be disposed at the following:

  • playgrounds;
  • children’s play areas;
  • residential yards;
  • areas where human contact occurs on a continuous basis;
  • areas near drinking water wells;
  • wellhead protection areas for public drinking-water supplies; and
  • sites with karst features, including sinkholes, disappearing streams and caves.

Prior to reuse, trash, leaves and other debris must be removed from the sweepings. This removal is often accomplished by screening, but other methods may also be used. Dispose of trash and debris removed from the sweepings by

  • recycling, such as aluminum cans;
  • composting, such as leaves; or
  • sending to a Municipal Solid Waste Landfill (MSW) immediately after being screened.

Street sweepings that are not screened for trash and debris are considered industrial solid waste and must be disposed of at a permitted solid waste facility that can accept the waste. Unscreened street sweepings must also be stored in accordance with solid waste storage standards (Minn. R. 7035.2855).

If street sweepings are screened prior to being stockpiled, they are exempt from Minnesota solid waste storage standards. Street sweepings can be reused in any of the following ways without MPCA approval, provided that all solid waste has been screened from the sweepings.

  • Mix with new salt/sand mixture for winter application to roads, parking lots or sidewalks
  • Use as daily cover material at a permitted solid waste landfill, provided that the landfill is approved to use street sweepings as Alternate Daily Cover (ADC).
  • Use as material in commercial and industrial development projects, road restoration or construction projects.

If sweepings are used as cover or fill, they must meet the following requirements.

  • Separation distances
    • 200 feet from lakes, rivers, streams, wetlands, intermittent streams, tile inlets, and karst features
    • 3 feet from groundwater
    • 3 feet from fractured bedrock
    • 50 feet from potable water supplies
  • Seed or cover
    • Within 7 days on slopes greater than 3:1
    • Within 14 days on slopes between 10:1 and 3:1
    • Within 21 days on slopes flatter than 10:1

Other entities (e.g. states, cities) have similar information about managing street sweepings, with some differences from Minnesota. Below are links to documents describing how sweepings are managed in other locations.

The following table summarizes potential management options for sweeping material.

Street sweeping management options
Link to this table

Disposal option Description
Disposed at solid waste landfill Street sweepings are gathered, stockpiled, and hauled to a municipal solid waste landfill or private disposal site.
Garbage/debris to landfill Street sweeping material is screened and garbage/debris (non-recyclable or non-organic trash materials) are separated and landfilled.
Reuse: Compost Street sweeping material is screened and organic materials (e.g., fall leaves) are composted.
Reuse: Recycling Street sweeping material is screened and recyclable materials (e.g., metal, paper, glass, aluminum cans) are disposed via recycling.
Reuse: Alternate daily cover (ADC) Street sweeping material is screened for removal of recyclable materials, organic materials, and trash. The remaining fines/dirt are used as alternate daily cover (ADC) at landfill sites.
Reuse: Fill dirt Street sweeping material is screened for removal of recyclable materials, organic materials, and trash. The remaining material is used in commercial or industrial development, road restoration, or construction projects. The fill is intended to be used for an engineered purpose.
Reuse: Subgrade material Street sweeping material is screened for sand, which is used as subgrade material.
Reuse: Aggregate in concrete or asphalt Street sweeping material is screened for removal of recyclable materials, organic materials, and trash. The remaining material can be used as aggregate for concrete or asphalt.
Reuse: Winter application Street sweeping material is screened for removal of recyclable materials, organic materials, and trash. The screened sand is mixed with salt/sand mixture for winter application to roads, parking lots or sidewalks.
Reuse: Bulking agent Street sweeping material is screened for removal of recyclable materials, organic materials, and trash and remaining material is used as a bulking agent for wastewater sludge or septage disposal. The mixed material is disposed in a permitted lined or unlined sludge or septage landfill.
Reuse: Spill cleanups Street sweeping material is screened for removal of recyclable materials, organic materials, and trash. Street sweepings that have been determined to be non-hazardous may be used as absorptive material to contain or to absorb hazardous materials in emergency situations.
Reuse: Waste to energy Street sweeping material is screened for removal of recyclable materials, organic materials, and trash. The larger trash and organic materials (e.g., vegetation) can be used in a waste to energy facility to produce electricity.

Testing street sweepings

Testing is not required for the uses described above. You may choose to test sweepings if the following conditions apply.

  • You suspect the sweepings may fail hazardous waste criteria
  • Local testing requirements exist for using the material

If you are testing to determine water, phosphorus, or organic content for use with phosphorus credit calculator, see Methods for sampling street sweeping material - Standard Operating Procedures.

Results of survey on managing street sweepings

We conducted a survey of stakeholders who conduct street sweeping, mostly at the municipality level. Survey questions included the following.

  • Which of the following best describes how do you manage your sweepings?
    • Not screened; landfilled
    • Screened; Sweepings are screened and the organic portion utilized
    • Depending on season or other factors we screen sometimes and not other times
    • Other
  • If you utilize the organic portion, how is it used?
    • Composted and used as cover (e.g. at landfills, construction sites, etc.)
    • Composted and made available for residents
    • Given or delivered to another entity (e.g. a composting facility)
    • Other uses
  • If you were to significantly increase the amount of organic material you collect from sweeping, how big a challenge would managing the material be?
    • A big challenge
    • Somewhat of a challenge
    • Not a challenge
    • I'm not sure

Results

References

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This page was last edited on 22 September 2022, at 16:16.