931 BROADWAY TEUTSCH STUDENT HOUSING 2018-03-07

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL 3.2.5 BMP C106: Wheel Wash Purpose Wheel washes reduce the amount of sediment transported onto paved roads by motor vehicles. Conditions of Use When a stabilized construction entrance (see BMP C105) is not preventing sediment from being tracked onto pavement. Wheel washing is generally an effective BMP when installed with careful attention to topography. For example, a wheel wash can be detrimental if installed at the top of a slope abutting a right-of-way where the water from the dripping truck can run unimpeded into the street. . Pressure washing combined with an adequately sized and surfaced pad with direct drainage to a large 10 x � 10-foot sump can be very effective. � Design and/nstallation Specifications 1. Applicable details are shown in Figure 3.1. A ininimum of 6 inches of asphalt treated base over crushed base material or 8 inches over a good subgrade is recommended to pave the wheel wash. 2. Use a low clearance truck to test the wheel wash before paving. Either a belly dump or lowboy will work well to test clearance. 3. Keep the water level from 12 to 14 inches deep to avoid damage to truck hubs and filling the truck tongues with water. 4. Midpoint spray nozzles are only needed in extremely muddy conditions. 5. Wheel wash systems should be designed with a small grade change, 6 to 12 inches for a 10-foot- wide pond, to allow sediment to flow to the low side of pond to help prevent re-suspension of sediment. A drainpipe with a 2-to 3-foot riser should be installed on the low side of the pond to allow for easy cleaning and refilling. Polymers may be used to promote coagulation and flocculation in a closed-loop system. Maintenance Standards 1. The wheel wash should start out the day with fresh water. 2. The washwater should be changed a minimum of once per day. On large earthwork jobs where more than 10 to 20 trucks per hour are expected, the washwater will need to be changed more - often. 3. Wheel wash or tire bath wastewater shall be controlled by pumping back on site to an approved . infiltration facility, or otherwise must be prevented from discharging into systems tributary to - state surface waters. Options include discharge to the sanitary sewer, or discharge to an approved offsite treatment system. For discharges to the sanitary sewer, permits must be obtained from the City's Industrial Pretreatment Program at(425)257-8874. Volume 11— Construction Stormwater Pollution Prevention 3-6