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<br />For each of these ditches, the critical flow location must be <br />determined and protected against scouring and channel breaching <br />with riprap (see Ponds and Impoundments). Ditches A, B, D, and E <br />are of particular concern since these ditches carry runoff from <br />undisturbed areas. The following stipulation is proposed. <br />Ditches A and B east, D, and E must be checked for <br />reaches where supercritical flow or hydraulic jumps <br />occur and protection provided at that point. <br />Ditches A, B, C, and D all outlet into relatively minor <br />drainages. There is a potential for erosion damage occuring <br />since the natural drainage patterns have been augmented in these <br />areas. Therefore the following stipulation is proposed. <br />The applicant must commit to monitoring drainages <br />below ditch A, B, C, and D outlets for erosion damage <br />and repairing same within 30 days after such damage is <br />Identified. <br />Culverts <br />There are six culverts shown on Figure 2 and another (Bush <br />Draw culvert) mentioned in the text. Cross Sections are not pro- <br />vided for culvert installations nor are complete design specifi- <br />cations made available. The applicant used Manning's equation <br />Q 1,486 A R 2~3 S 1~2 <br />n <br />to calculate culvert capacity. <br />Manning's equation is not acceptable for culvert design <br />because culvert capacity in most cases is determined by inlet or <br />outlet conditions rather than by friction losses with in the cul- <br />vert. <br />-75- <br />