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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Chapt", 2-Storm Water Pollution Pr.Vtllltion PlBn <br /> <br />so that any soil disturbing activity such as: clearing, stripping, excavation, backfill, stock piling <br />(topsoil or other fill material), and paving will be inside of the limit. The limit of disturbance should <br />also include roads for construction vehicles unless those roads are paved (or stabilized) and have <br />measures to reduce tracking of sediments. When drawing the line try to leave room for the control <br />structures which may be required (this may be difficult. but you can always redraw the limit of <br />disturbance after you design the control structures). The limit of disturbance should be a closed <br />boundary line around the entire disturbed area. There can be "islands" of undisturbed area inside <br />the limit of disturbance, for example, a tree or group of trees which are to be preserved. These <br />islands should be encircled with a limit of disturbance. <br /> <br />Drainage Patterns <br /> <br />In addition to the slopes anticipated after grading, and areas of soil disturbance your Storm Water <br />Pollution Prevention Plan site map should also indicate the drainage patterns of the site after the <br />major grading activities. <br /> <br />The suggested method for showing this is with a topographic map of the site which indicates <br />drainage basin boundaries and drainage channels or pipes. A drainage basin for the purposes of tb" <br />Storm Water Pollution Prevention Plan is an area of the site in which water, sediments and <br />dissolved materials drain to a common outlet (such as a swale or storm drain pipe) from the site. <br />There can be one or more drainage basins on a site. Drainage boundaries are closed lines which <br />start and end at the common outlet. Drainage boundaries typically follow the high points on a site <br />including hill tops, ridges, roads, etc. Drainage areas do not overlap. To determine the drainage <br />basin boundaries, ask yourself where will rain falling on this portion flow off of the site. Areas that <br />drain to different points are in different drainage areas. Drainage boundaries can be changed by <br />grading and structural controls. The site map should indicate the drainage boundaries after the <br />major grading has occurred or structural controls installed. It may be necessary to change the <br />drainage boundaries after you select your structural controls. If you do not provide a topographic <br />site map, use arrows to indicate which direction water will flow. Show the areas where there will <br />be overland flow and the location of swales or channels. If there is a new or proposed <br />underground storm drain system on the site then this should be indicated on the Storm Water <br />Pollution Prevention Plan site map as well. It is recommended that the pipe diameter and slope also <br />be included on the site map. <br /> <br />Please note that the Storm Water Pollution Prevention Plan site map is not complete until you have <br />indicated the locations of the major control structures and the areas where stabilization is expected <br />to occur. These items are discussed in Section 3.3.4. <br /> <br />September 1992 <br /> <br />2-7 <br />