Agenda - Council - 04/13/2021 - Laserfiche WebLink

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820 (1) If the project includes work at or below the OHWL, the commissioner has already approved 821 or permitted the project. 822 (2) The structures are used only to correct an established erosion problem as determined by the 823 City of Ramsey. 824 (3) The size and extent of the structures are the minimum necessary to correct the erosion 825 problem and are not larger than the following, unless a professional engineer determines 826 that a larger structure is needed to correct the erosion problem: 827 (i) Retaining walls must not exceed five feet in height and must be placed a minimum 828 horizontal distance of ten feet apart; and 829 (ii) Riprap must not exceed the height of the regulatory flood protection elevation. 830 c. Repair of existing rock riprap, retaining walls, and other erosion control structures above the OHWL 831 does not require a permit provided it does not involve any land alteration under Section 117- 832 148(j)2 (Land alteration permit). 833 4. Stormwater management. 834 a. In the bluff impact zone, storm water management facilities are prohibited; except by permit if: 835 (1) There are no alternatives for storm water treatment outside the bluff impact zone on the 836 subject site; 837 (2) The site generating runoff is designed so that the amount of runoff reaching the bluff impact 838 zone is reduced to the greatest extent practicable; 839 (3) The construction and operation of the facility does not affect slope stability on the subject 840 property or adjacent properties; and 841 (4) Mitigation based on the best available engineering and geological practices is required and 842 applied to eliminate or minimize the risk of slope failure. 843 b. In the water quality impact zone, development that creates new impervious surface, as allowed 844 by exemption in Section 117-148(1) (Exemptions), or fully reconstructs existing impervious 845 surface of more than 10,000 square feet requires a storm water permit or approved storm water 846 plan. Multipurpose trails and sidewalks are exempt if there is down gradient vegetation or a filter 847 strip that is at least five feet wide. 848 c. In all other areas, storm water runoff must be directed away from the bluff impact zones or 849 unstable areas. 850 5. Development on steep slopes. Construction of structures, impervious surfaces, land alteration, 851 vegetation removal, or other construction activities are allowed on steep slopes if: 852 a. The development can be accomplished without increasing erosion or storm water runoff; 853 b. The soil types and geology are suitable for the proposed development; and 854 c. Vegetation is managed according to the requirements of Section 117-148(i) (Vegetation 855 management). 856 6. Conditions of land alteration permit approval. 857 a. Temporary and permanent erosion and sediment control measures retain sediment onsite consistent 858 with best management practices in the Minnesota Stormwater Manual; 24