Concrete, Stucco, Plaster and Grout

Concrete, stucco, plaster and grout that enters creeks and other waterways is harmful to aquatic life. The lime found in these materials easily dissolves in water, just like sugar. This lime is so alkaline (high in pH) that it is deadly to the fish and critters that live in our creeks. Concrete waste can also block or obstruct storm drain pipes and cause local flooding. For these reasons, it's very important to use Best Management Practices (BMPs) in order to prevent these materials from entering storm drains, ditches, and creeks.

Remember that you are responsible for the actions of contractors and other people assisting with the work.  Be sure to discuss the BMPs below with workers to avoid illicit discharges and enforcement actions, such as fines, civil penalties and stop work notices, by local, state and federal agencies.

Working with Concrete, Stucco, Plaster and Grout

1.  Planning Ahead

• Avoid mixing up or ordering more concrete than you will use.
• Schedule work for dry weather whenever possible and store materials in a dry location.
• Store cement and plaster bags under cover, away from drainage areas.
• Educate employees, subcontractors and suppliers on concrete waste management.

2.  Cleaning Up

• Avoid cleaning concrete equipment where wastewater could enter a street, gutter, storm drain, ditch or stream.
• The preferred method of disposing of wastewater from equipment cleaning is to use a concrete washout that contains the wastewater and material. A concrete washout is a tarp-lined (minimum 10 mil) basin made from a pit in the ground, lumber or straw bales that allows waste water to evaporate. The remaining dry concrete waste can be disposed of in the trash or recycled.
• If you have a small project and there's no rain in the forecast, you can allow the wastewater from equipment cleaning to soak into dirt areas provided the area is large enough to contain and infiltrate all the wastewater. Remember that this wastewater has a high pH and could be harmful to the plants in your yard.
• If possible, recycle wash water by pumping it back into the concrete delivery truck for reuse or disposal at the concrete batch plant.
• When cleaning up after driveway or sidewalk construction, wash dust onto dirt areas, NOT into the street or storm drain.
• Saw-cut and grinding slurry must not be allowed to enter storm drains or waterways. Use a vacuum to collect wastewater and dispose of it properly or divert the slurries to dirt areas.

3.  Recycling

• After breaking up concrete or asphalt, recycle the pieces at a crushing company (Napa Recycling (707) 255-5200 or Upper Valley Recycling (707) 963-7988).  Small amounts of dry waste may be disposed of in the trash.

4.  Report Illicit Discharges

• Please report illicit discharges to your local Stormwater Agency by calling the appropriate Stormwater Hotline below.