Mandatory Compliance


You Have to Comply...


The 1972 amendments to the Clean Water Act (CWA), prohibit the discharge of any pollutant into navigable waters of the United States from a point source unless the discharge is authorized by a National Pollutant Discharge Elimination Systems (NPDES) permit.  It was first thought that pollution primarily came from industrial activities but over time it became evident that storm water runoff from construction sites was also a significant contributor to water quality problems.


Construction sites generally can contribute 10 to 20 times more sediment than agricultural lands and 1,000 to 2,000 more times than forestlands. During a short period of time, construction sites can contribute more sediment than can be deposited over several decades, causing physical and biological harm to our Nation’s waters.


Phase I of the NPDES storm water program addresses runoff from construction sites disturbing 5 acres or more of land.  On March 10, 2003, Phase II went into effect, requiring construction sites disturbing 1 or more acres of land to now adhere to the NPDES permit.


Both Phase I and II or the NPDES storm water program require that construction sites implement Storm Water Pollution Prevention Plans (SWPPP) addressing appropriate Best Management Practices (BMP’s) to minimize discharge of pollutants from the site.  One such BMP is the utilization of a concrete washout containment area to control all concrete waste materials generated, including the washwater.


Best Management Practices (BMP's)


California has emerged as a leader in being proactive in its education and enforcement of BMP’s and two authorities have emerged within for the implementation of various BMP’s related to construction; Caltrans and the California Stormwater Quality Association (CASQA).  Both entities have similar BMP guidelines relating to concrete washout containment and specifically address Concrete Waste Management (WM-8) and Liquid Waste Management (WM-10), and their key points are summarized below.


Concrete Waste Management WM-8


This BMP is implemented when concrete is used as a construction material or slurries containing Portland cement concrete (PCC) are generated from saw cutting, etc. 

  • DO NOT wash out concrete trucks into storm drains, open ditches, streets or streams.
  • Slurry residue SHOULD NOT be allowed to enter storm drains or watercourses, should be vacuumed and disposed of in accordance with WM-10.
  • Concrete washout from concrete trucks can be washed into concrete pumper trucks and discharged into
  • Designated washout area or properly disposed offsite.
  • Temporary concrete washout facilities SHALL BE constructed with sufficient quantity and volume to
  • contain all liquid and concrete waste generated by washout operations.
  • Plastic lining material should be a minimum of 10 mil polyethylene sheeting and should be free of holes,
  • Tears, or other defects that compromise the impermeability of the material.
  • Washout facilities must be cleaned, or new facilities must be constructed and ready for use once the washout is 75% FULL.


Liquid Waste Management WM-10


  • Contain liquid wastes in a controlled area, such as a holding pit, sediment basin, roll-off bin, or portable tank.
  • Containment devices must be structurally sound and leak free and contain all liquid wastes.
  • Containment devices must be of sufficient quantity or volume to completely contain the liquid waste generated.