Best Management Practices (BMPs) – Contractor Storm Water Protection

• Always cover dumpsters with a rollback tarp or lid.
• Areas around dumpsters should be swept daily.
• Perimeter controls should also surround dumpsters and all Port-a-Potties.
• If dumpsters or Port-a-Potties are kept in street, encroachment permits are required.

Perimeter Controls
• Gravel bags, silt fences, and straw wattles are acceptable perimeter controls, and must be used to surround the entire site to control run-on and run-off.
• Avoid running over perimeter controls with vehicles or heavy equipment, as they can damage the materials.
• Keep extra absorbent materials and/or a wet/dry vacuum on site to quickly pick up unintended spills.
• Sites must also be checked and maintained daily.

Materials Storage
• All building materials and fuel stored on the site must be contained and covered.
• It is illegal for contractors to wash out paint brushes in the street or dump any residues in the storm drain.
• Paint brushes and spray guns must be contained and disposed of properly.

Building Materials/Staging Areas
• Construction materials must be stored on site at all times unless an encroachment permit has been obtained.
• Building materials should always be covered when not in use to prevent run-off cause by wind or rain.

Basement/Sump De-watering
• Water collected in basements or detention basins due to natural groundwater seepage or rain events must be allowed to evaporate or be pumped to trucks with holding tanks for offsite disposal.
• Pumping this water onto the street or an adjacent property is an illegal discharge prohibited by law.

Tracking Controls
• All entrances and exits on the site must have coarse gravel or steel shaker plates to limit offsite sediment tracking.
• Public roads must be swept to remove any dirt or sediment tracked offsite.

Concrete Tucks/Pumpers
• Pumpers must be surrounded by perimeter controls, such as gravel bags.
• Plastic sheets also must be placed beneath concrete pumpers, at all times, and residual materials must be cleaned up.
• Washout areas must be used whenever cleaning trucks.

Washout Areas
• The disposal of “wet” construction materials (i.e. paint, stucco, and concrete) should be handled in the washout area.
• Use a berm and/or plastic sheet to collect and contain liquids and prevent run-off in nearby areas.
• The washout area must be checked and maintained daily to ensure compliance.
• Washout liquids must be disposed of properly.
• Washout areas should be adequately covered and protected during rain events.

Dirt and Grading
• Mounds of dirt or gravel should be stored on site.
• These materials must also be covered each day with a tarp, visqueen, or other form of protection.
• Visqueen and/or tarps must be available and on site to cover 125% of exposed areas during the rainy season (October 1st – April 30th).

Earthmoving Equipment
• All earthmoving equipment should be stored on site.
• Maintenance should also be conducted on the site, and tracks and trails left by equipment leading to and from the site should be cleaned up immediately.

Storm Drains
• Storm drains must be protected at all times with perimeter controls, such as gravel bags or straw wattles.
• Sediment accumulation should be removed frequently.

For questions or additional information, please contact the Clean Water Program at 858-704-3652 or through email at

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