Laserfiche WebLink
t <br /> • Pressure washing combined with an adequately sized and surfaced pad <br /> with direct drainage to a large 10-foot x 10-foot sump can be very <br /> effective. <br /> • Discharge wheel wash or tire bath wastewater to a separate on-site <br /> treatment system that prevents discharge to surface water,such as <br /> closed-loop recirculation or upland land application,or to the sanitary <br /> sewer with local sewer district approval. <br /> • Wheel wash or tire bath wastewater should not include wastewater <br /> from concrete washout areas. <br /> Design and Suggested details are shown in Figure 4.1.2. The Local Permitting <br /> Installation Authority may allow other designs. A minimum of 6 inches of asphalt <br /> Specifications treated base(ATB)over crushed base material or 8 inches over a good <br /> subgrade is recommended to pave the wheel wash. <br /> Use a low clearance truck to test the wheel wash before paving. Either a <br /> belly dump or lowboy will work well to test clearance. <br /> C <br /> Keep the water level from 12 to 14 inches deep to avoid damage to truck <br /> hubs and filling the truck tongues with water. <br /> A' <br /> I <br /> Midpoint spray nozzles are only needed in extremely muddy conditions. <br /> Wheel wash systems should be designed with a small grade change, 6-to <br /> 1-inches for a 10-foot-wide pond,to allow sediment to flow to the low <br /> side of pond to help prevent re-suspension of sediment. A drainpipe with a <br /> 2- to 3-foot riser should be installed on the low side of the pond to allow <br /> for easy cleaning and refilling. Polymers may be used to promote <br /> coagulation and flocculation in a closed-loop system. Polyacrylamide <br /> ; V (PAM)added to the wheel wash water at a rate of 0.25 -0.5 pounds per <br /> 1,000 gallons of water increases effectiveness and reduces cleanup time. If <br /> PAM is already being used for dust or erosion control and is being applied <br /> by a water truck, the same truck can he used to change the wash water. <br /> Maintenance The wheel wash should start out the day with fresh water. <br /> Standards <br /> The wash water should be changed a minimum of once per day. On large <br /> earthwork jobs where more than 10-20 trucks per hour are expected, the <br /> wash water will need to be changed more often. <br /> a <br /> r <br /> j <br /> Vohuue 11—Construction Storn imler•Pollrrlion Prevention-Augusl 2012 <br /> 4-10 <br />