Agenda - Planning Commission - 02/02/2017

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Subpart 10.B. was added to ensure that isolated cliffs and rock outcrops such as Robinson's Rocks in Gray Cloud Island Township are protected. These features, which are often nearly vertical, would otherwise not be captured by the bluff definition. The proposed definition also clarifies that a bluff is a "natural topographic feature" to differentiate natural features, which the rules seek to protect, from man-made features. The various bluff protection standards do not apply to man-made features such as highway and railroad embankments, road ditches, and reclaimed slopes. A variety of bluff -related definitions are used to define the specific spatial extent of a bluff, the scope of required bluff protections, and to improve the ability of local governments to administer the rules. When determining the limits of a bluff it is important to clearly define where the bluff begins and ends. The following definitions were developed to aid in this determination. These definitions will be used to map bluff features when reviewing development proposals and for accurate delineation by surveyors "in the field": • A bluffline, which is a line delineating the top of the bluff. Proposed Minn. R. 6106.0050, subp. 10. More than one bluffline may be encountered proceeding landward from the river. Id. • The toe of the bluff is a line along the bottom of a bluff, requiring field verification, such that the slope above the line exceeds 18 percent and the slope below the line is 18 percent or less, measured over a horizontal distance of 25 feet. Proposed Minn. R. 6105.0050, subp.77. • The top of the bluff is a line along the top of a bluff, requiring field verification, such that the slope below the line exceeds 18 percent and the slope above the line is 18 percent or less, measured over a horizontal distance of 25 feet. Proposed Minn. R. 6105.0050, subp. 78. While bluff mapping software can estimate the general location of bluffs, field verification by a land surveyor is needed to identify blufflines. The location of the bluffline is particularly important in determining the placement of a structure on a lot and determining the height of a structure. See e.g. Proposed Minn. R. 6106.0120, subps. 2 and 3B (regarding the height of structures in relation to the bluffline and bluffline setback requirements). The toe of bluff and top of bluff definitions are derived from the state shoreland rules. Minn. R. 6120.2500, subps. lb and lc (2015). However, the proposed MRCCA rule uses a 25-foot horizontal segment instead of the 50-foot horizontal segment used in the statewide shoreland rules. Cf. Minn. R.6120.2500, subp. lb (2015) and Proposed Minn. R. 6105.0050, subp. 11. The 25-foot horizontal segment was used to provide a finer resolution of these features systems within the MRCCA, which is more heavily developed than the typical shoreland district. The concept of the bluff impact zone is the bluff and area around the bluff that will be protected by the proposed MRCCA rules. As illustrated in Figure 9, the bluff impact zone includes the bluff and land within 20 feet (from the top, sides, and toe) of the bluff. Proposed Minn. R. 6105.0050, subp. 9. The bluff impact zone is based on the definition used in the shoreland rules but includes the sides and toe of the bluff as protected areas. Cf. Minn. R. 6120.2500, subp. lc (2015) and Proposed Minn. R. 6106.0050, subp.9. 27