819 N BROADWAY WASHINGTON STATE UNIVERSITY 2018-05-11

BMP C203: Water Bars Purpose A small ditch or ridge of material is constructed diagonally across a road or right-of-way to divert stormwater runoff from the road surface, wheel tracks, or a shallow road ditch. Conditions of use Clearing right-of-way and construction of access for power lines, pipelines, and other similar installations often require long narrow right-of-ways over sloping terrain. Disturbance and compaction promotes gully formation in these cleared strips by increasing the volume and velocity of runoff. Gully formation may be especially severe in tire tracks and ruts. To prevent gullying, runoff can often be diverted across the width of the right-of-way to undisturbed areas by using small predesigned diversions. • Give special consideration to each individual outlet area, as well as to the cumulative effect of added diversions. Use gravel to stabilize the diversion where significant vehicular traffic is anticipated. Design and Height: 8-inch minimum measured from the channel bottom to the ridge top Installation Specifications • Side slope of channel: 2:1 maximum; 3:1 or flatter when vehicles will cross. • Base width of ridge: 6-inch minimum. • Locate them to use natural drainage systems and to discharge into well vegetated stable areas. • Guideline for Spacing: Slope % Spacing(ft) < 5 125 5 - 10 100 10 - 20 75 20 - 35 50 > 35 Use rock lined ditch • Grade of water bar and angle: Select angle that results in ditch slope less than 2 percent. • Install as soon as the clearing and grading is complete. Reconstruct when construction is complete on a section when utilities are being installed. • Compact the ridge when installed. • Stabilize, seed and mulch the portions that are not subject to traffic. Gravel the areas crossed by vehicles. February 2005 Volume ll— Construction Stormwater Pollution Prevention 4-65