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Concrete is used as a construction material <br />. It is not possible to dispose of all concrete wastewater and washout off -site (ready <br />mix plant, etc.). <br />• Concrete trucks, pumpers, or other concrete coated equipment are washed on -site. <br />. Note: If less than 10 concrete trucks or pumpers need to be washed out on -site, the <br />washwater may be disposed of in a formed area awaiting concrete or an upland <br />disposal site where it will not contaminate surface or ground water. The upland dis- <br />posal site shall be at least 50 feet from sensitive areas such as storm drains, open <br />ditches, or water bodies, including wetlands. <br />Design and Installation Specifications <br />Implementation <br />The following steps will help reduce stormwater pollution from concrete wastes: <br />• Perform washout of concrete trucks at an approved off -site location or in des- <br />ignated concrete washout areas only. <br />• Do not wash out concrete trucks onto the ground, or into storm drains, open <br />ditches, streets, or streams. <br />• Do not allow excess concrete to be dumped on -site, except in designated concrete <br />washout areas. <br />• Concrete washout areas may be prefabricated concrete washout containers, or <br />self -installed structures (above -grade or below -grade). <br />. Prefabricated containers are most resistant to damage and protect against spills <br />and leaks. Companies may offer delivery service and provide regular maintenance <br />and disposal of solid and liquid waste. <br />If self -installed concrete washout areas are used, below -grade structures are pre- <br />ferred over above -grade structures because they are less prone to spills and leaks. <br />• Self -installed above -grade structures should only be used if excavation is not prac- <br />tical. <br />Education <br />. Discuss the concrete management techniques described in this BMP with the <br />ready -mix concrete supplier before any deliveries are made. <br />. Educate employees and subcontractors on the concrete waste management tech- <br />niques described in this BMP. <br />• Arrange for contractor's superintendent or Certified Erosion and Sediment Control <br />2014 Stormwater Management Manual for Westem Washington <br />Volume ll - Chapter 4 - Page 318 <br />