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Hennepin Conservation District <br />Repairing Erosion Damage <br />1.0 Slope Restoration <br />Eroded areas can be restored by regrading existing material. Clean dirt fill should <br />be used where additional material is needed. The regraded surface must have a <br />uniform slope with a level gross -section; it must not have any depressions or bumps. <br />The fill should be covered with four inches of loamy topsoil for the vegetative cover. <br />Where possible, eroded areas should be regraded to slopes no greater than 1 on <br />2 (50% grade). This can be achieved by extending the regraded slope at the toe, <br />cutting the slope back at the crest, or c•,,* structing a retaining wall at the top of the <br />slope. <br />Six-inch diameter draii 1s must be installed along the toe of all affected alo .. 's and <br />behind all retaining walls. Corrugated polyethylene perforated tubing is <br />recommended. Drains shall be laid to a neat line and grade in a trench excavated <br />into undisturbed soil. There should be no void spaces between the tubing and the <br />walls of the trench after backfilling. Turn both ends to provide outlets. Except for <br />outlets, drains must be three feet below the final graded surface. A rodent guzrd <br />must be placed over all outlets. <br />Retaining walls can be used to shorten the regraded slob: . The retaining wall <br />shou'd be places: at the top of the slope and not exceed five feet in height. Six-inch <br />drains must be installed behind all retaining walls using specifications cited above. <br />Drains should be placed at the same elevation as the bottom of the expes:-d wall and <br />four feet behind the wall where possible. An engineer must be consulted for the <br />design of retaining walls needed to .nrotect structures. <br />205 Ridge Pura Bldg 12450 Wayzata Boulevard Minnotunka Minnesot 1 55343 Telephone i6l.) 544-8572 <br />I <br />