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CITY OF EVERETT STORMWATER MANAGEMENT MANUAL 6. The mixing,production,and pouring areas should be paved. A sump drain in these areas is probably not advisable due to potential clogging problems, but could be used in a curing area. Sweep these areas to remove loose aggregate and recycle or dispose of properly. 7. Use storm drain covers or similarly effective containment devices to prevent runoff from entering the stormwater drainage system. Accumulations of dirty runoff must be disposed of properly. Contact the City's Surface Water Management Section(425)257-8800 for information about water quality treatment BMPs for these types of operations. Visit Ecology's Web site for accepted water quality treatment at: <http://www.ecy.wa.gov/programs/wq/stormwater/index.html>. The use of any treatment BMP must not result in the violation of groundwater or surface water quality standards. A3.2 Concrete Pouring, Concrete Cutting, and Asphalt Application at Temporary Sites Description of Pollutant Sources: This activity applies to businesses and public agencies that apply asphalt or pour or cut concrete for building construction and remodeling,road construction,sidewalk, curb and gutter repairs and construction, sealing of driveways and roofs,and other applications. These activities are typically done on a temporary site-to-site basis where permanent BMP measures do not apply. Concrete pouring activities can not only severely alter the pH of receiving waters,but slury from aggregate washing can harden in storm pipes,thus reducing capacity and creating flooding problems. Pollutants of concern include toxic hydrocarbons,toxic organic compounds, oils and greases, heavy metals,suspended solids,and pH. Pollutant Control Approach: Train employees on proper procedures,sweep or shovel aggregate chunks,collect accumulated runoff and solids,and wash equipment in designated areas. Required BMPs The following BMPs or equivalent measures are required of all businesses and agencies doing concrete pouring and asphalt application at temporary sites: I. Employees must be educated on the pollution hazards of concrete and asphalt application and cutting. 2. Loose aggregate chunks and dust must be swept or shoveled and collected(not hosed down a storm drain)for recycling or proper disposal at the end of each workday,especially at work sites such as streets,driveways,parking lots,sidewalks,curbs,and gutters where rain can readily pick up the loose material and carry it to the nearest stormwater conveyance. Small amounts of excess concrete,grout,and mortar can be disposed of in the trash. 3. Storm drain covers or similarly effective containment devices must be placed over all nearby drains at the beginning of each day. Shovel or vacuum slurry and remove from the site. All accumulated runoff and solids must be collected and properly disposed of(see BMP S.2 in Chapter 4 for disposal options)at the end of each workday, or more often if necessary. 4. Exposed aggregate washing,where the top layer of unhardened concrete is hosed or scraped off to leave a rough finish,must be done with a mechanism for containment and collection of the discarded concrete slurry(such as the storm drain covers mentioned above). The easiest way to contain the washwater will be to direct the washings to a hole in the ground where the water can percolate into the ground and the solids later covered with soil. 5. Cleaning of concrete application and mixing equipment or concrete vehicles on the work site must be done in a designated area where the rinse water is controlled. The rinse water must either be collected for proper disposal or put into a hole in the ground where the water can percolate away and the solids later covered with soil or recovered and disposed of or recycled. Volume IV—Source Control 3-17