Stormwater pollution prevention tips: Parking/storage area maintenance, part I

Parking lots and storage areas can contribute trash, suspended solids, hydrocarbons, oil and grease, heavy metals and other substances to receiving water via polluted runoff or nonstormwater discharges.

The California Stormwater Quality Association's Industrial and Commercial Handbook offers the following tips for properly maintaining parking and storage areas to prevent stormwater pollution. For more information, visit


  • Keep parking and storage areas clean and orderly. Remove debris in a timely fashion.
  • Allow sheet runoff to flow into biofilters (vegetated strip and swale) and/or infiltration devices.
  • Use sand filters or oleophilic collectors for oily waste in low quantities.
  • Arrange rooftop drains to prevent drainage directly onto paved surfaces.
  • Design lot to include semipermeable hardscape.
  • Discharge soapy water remaining in mop or wash buckets to the sanitary sewer through a sink, toilet, clean-out or wash area with drain.

Controlling litter

  • Post "No Littering" signs and enforce anti-litter laws.
  • Provide an adequate number of litter receptacles.
  • Clean out and cover litter receptacles frequently to prevent spillage.
  • Provide trash receptacles in parking lots to discourage litter.
  • Routinely sweep, shovel and dispose of litter in the trash.

Surface cleaning

  • Use dry cleaning methods (e.g., sweeping, vacuuming) to prevent the discharge of pollutants into the stormwater conveyance system if possible.
  • Establish frequency of public parking lot sweeping based on usage and field observations of waste accumulation.
  • Follow the procedures below if water is used to clean surfaces:
    • Block the storm drain or contain runoff.
    • Collect and pump wash water to the sanitary sewer or discharge to a pervious surface. Do not allow wash water to enter storm drains.
    • Dispose of parking lot sweeping debris and dirt at a landfill.
  • Follow the procedures below when cleaning heavy oily deposits:
    • Clean oily spots with absorbent materials.
    • Use a screen or filter fabric over inlet, then wash surfaces.
    • Do not allow discharges to the storm drain.
    • Vacuum/pump discharges to a tank or discharge to sanitary sewer.
    • Appropriately dispose of spilled materials and absorbents.

Next week, part II of these tips will address surface repair, spill response and other subjects.

This article originally appeared in the 04/01/2005 issue of Environmental Protection.

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