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Parking Lot and Street Sweeping

General

Parking lot and street sweeping prevents sediment, heavy metals, and other pollutants from reaching receiving waters by removing them from impervious areas before they reach storm drains. Impervious areas accumulate sediment, lawn and leaf trimmings, trash, and other debris, along with heavy metals and other pollutants. As stormwater flows over these surfaces, these substances are carried along with it, polluting waterways and increasing the sediment load of the water body.

Parking lot and street sweeping is applicable on any impervious surface where a street sweeper may safely travel. Because removing smaller particles is often difficult, street sweeping should be used in conjunction with other practices, such as Permanent Seeding, Native Plants or Grassed Swale to minimize the amount of material that must be removed.

Advantages

  • Reduces the amount of sediment, heavy metals and other pollutants that reach receiving waters
  • Helps prevent storm sewers from clogging
  • Improves easthetics
  • Especially effective when used in parking lots

Disadvantages

  • Limited effectiveness on streets with parked cars
  • Waste may contain heavy metals and other pollutants

Methods

Parking lot and street sweeping may be performed by one of two mechanized methods: broom sweeping or vacuum sweeping. Broom sweepers remove larger particles and are effective on wet surfaces. These sweepers are more economical than vacuum sweepers, but release dust into the air while in use. Vacuum sweepers are more effective at removing pollutant-laden fine particles, but are generally ineffective when used on wet surfaces.

Timing

Parking lot and street sweeping should be performed as often as is practical and no less than twice a year. Increasing the frequency of the practice increases the amount of waste that is collected, and, as a result, increases the efficiency of the practice.

Sweeping removes the materials that tend to accumulate in parking lots and on streets throughout the year, such as salt, sand, and other de-icing substances, along with trash and other debris. Leaves and grass clippings should also be collected to prevent them from entering and potentially clogging storm drains. The timing of these operations is important, as sweeping too late in the spring or too early in the fall will result in less than peak loads being collected, reducing the efficiency of the practice as well as increasing the pollution potential.

Additional sweeping is recommended on surfaces with large traffic volumes, during and after construction activities, and after any other activity that causes sediment, pollutants, or other debris to accumulate on roadways and impervious areas.

Disposal

The waste that is collected by street sweepers may be separated by screening, which removes yard wastes, trash, and other debris. Leaves and grass clippings may be removed and sent to a composting facility, while trash and other debris may be recycled or sent to a landfill. Street sweepings may also be used as cover material for landfills or be landfilled themselves. However, sweepings often contain a wide variety of organic and inorganic pollutants and testing may be required to determine disposal options. As a result, street sweepings should be disposed with care.

Operation and Maintenance

  • Sweeping operations should prevent materials from being directed toward storm drain inlets
  • Holding and disposal sites for collected materials should be located so that it is not washed back into storm drain inlets
  • Sweeping should be performed prior to storm events to maximize the amount of waste collected
  • Routine maintenance should be performed on street sweepers to keep them operating properly and effectively

Method to Determine Practice Efficiency

Parking lot/street sweeping may be used to help meet the 80% total suspended solids (TSS) reduction required by the ordinance. If a street sweeping program is implemented that includes regular sweeping that is performed properly and provides for proper disposal of accumulated materials, street sweeping, when used in conjunction with other management practices, provides a TSS reduction of up to 10%.