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Clayton Group Services Page 2 Standard Operating Procedures SOP -6 - Groundwater Well Development and Surveying within the well's water column. A pump or bailer is then used to remove the dislodged material and groundwater, generally about 5 well volumes, as described below. • Over Pumping - Using this method, the well is pumped rapidly dislodging unwanted fine material. This method generally is used with Mechanical Surging. • Air Lift Pumping - Using this method, an air lift pump is operated by cycling the air pressure on and off for short periods of time. This acts to surge the well. Then, a low pressure is applied to remove fines dislodged by surging. • Well Jetting -Using this method, the well screen area is jetted with water while at the same time air-lift pumping the well. In general, a minimum of 5 well volumes of water and sediment should be removed during well development, generally either by pumping or bailing the well. However, well development (removal of water) should continue until the water is free of drilling fluids and fines as indicated by stabilized pH, temperature, and specific conductivity as well as visibly clear. The CRWQCB-LA recommends that water with less than 5 NTU of turbidity measurement be obtained to be acceptable for volatile organic compound (VOC) analysis. The County of Los Angeles Department of Public Works, Waste Management Division requires that water from the developed well must have less than 10 ppm of settleable solids. One well volume can be calculated by the equation: V=3.14xr2x(di-d2)x7.481 Where: r = radius of the well in feet d, = depth of well in feet d2 = depth to water in feet V = one well volume in gallons or For a 2 -inch well: V = 0.17Ga1/Linear Ft. x (d, - d2) For a 4 -inch well: V = 0.66Gal/Linear Ft. x (d, - d2) d 1. d2, and V are as above. S:AErirnrAPrQiASPOs\SOP-6.doc