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Variance Justification Memo MEMO To: Lori Haak, City of Chanhassen From: Bruno Silikowski, Mutual Investments LLC RE: Variance Justification - Autobahn MotorPlex Site This memo supports our appeal for a change or variance to the City suggested Bluff Creek Overlay Line (BCOL). The only change that we are requesting is that instead of using the 908 foot contour elevation we use the 906 elevation. This change results in an extremely little difference in land within the BCOL (see elevation contour map) throughout the General Mills site and our land but does allow low land on our site to be used for ponding. Additionally, there is no impact on the wetland boundaries on either site. The low area on our land includes an incidental wetland. It is man-made and its genesis is a result of grading that was done on the site back in 1988-1989 timeframe (Sathre owned the site at that time, so we know this to be fact). If the appeal is agreed upon, we will only use the difference in the land for ponding purposes and it will, within 2-3 years, take on similar characteristics as the pond/wetland to the north. This area is by far the most reasonable location to place the ponding; it is the lowest point that can be used and this is where the water naturally flows. This ponding point is also the closest natural location that would allow the water coming from the railroad track to be channeled, in fact that water also flow to the area requested. This memo also demonstrates that the best place for the pond is where the incidental wetland is located, adjacent to the main wetland basin. There are many reasons but the most important are a natural water flow, better water quality entering the Bluff Creek, higher quality pond aesthetics, and significantly increased expenses for engineering work, excavating, grading, build ability, and piping. In summary, changing the BCOL from the 908 to 906 elevation is the most reasonable solution for ponding on this site. The only use for the land difference will be for ponding. Additional improvements to the BCOL could also be gifted, such as but not limited to additional plantings adjacent to existing wetland complex within the BCOL. We would coordinate with an Environmental Engineer to determine appropriate improvements to the wetland boundaries and upland to expand or enhance the existing wildlife habitat. We would propose to do this in cooperation with General Mills to provide a more comprehensive improvement plan. Sec. 20-58 General conditions for granting a variance - (I) There is undue hardship; it is not being able to use the area ofthe property where the storm water naturally flows. Reason being the area is currently within the BCOL primary line, and ponding is not allowed within the BCOL. Additional undue hardship is; that the next most logical place to put a storm water pond is along western upland slopes. This is not only a poor place to put the pond from the standpoint of water flow but also from an engineering standpoint (least structurally sound - being placed on a slope) and the storm water won't be filtered as much through the wetland before flowing into the Bluff Creek. Also, flow from existing gullies will not be able to be treated prior to it entering the BCOL. (2) The topography of this parcel makes this property quite different than the surrounding properties, bowl shaped. The overland flow on the site is largely from the east towards the west/northwest lowest. Currently, much of the flow is being directly to the incidental wetland area by actively eroding gullies. This incidental wetland area is where we are requesting a pond to be placed. (3) The variance is requested because it is the most reasonable solution to storm water ponding on this site. It would be the most structurally stable pond location, provide maximum filtering ofthe storm water and be in the place where the water is naturally flowing. (4) As stated above, the topography of this parcel makes for a natural storm water ponding location. (5) The opposite would occur, placing the ponding on this location will provide maximum filtering for the storm water thus improving the water quality entering the Bluff Creek. (6) If anything, the approval of this variance will enhance the quality of life for the surrounding neighbors, ecology and wildlife. Variance Justification on the 8200 Audubon Road Property. Storm water ponding is always a necessary challenge as a part of the development to protect downstream waterbodies and is somewhat of a peculiar problem on this site. The main body of the site slopes mostly from the east towards the West, however there is a higher area in the western portion of the site that drains back to the East creating a bowl shape where the storm water naturally settles in the lowest part ofthe property. In fact, this presents a natural place where the storm water ponding begs to be. Unfortunately, -25% of the needed storm water ponding falls within the Bluff Creek Overlay, but is still outside the defined wetland boundary, thus requiring a variance for the proposed solution. Striving to create a ponding area that provides the best rate and quality control for all runoff from this site prior to reaching the wetlands abutting Bluff Creek while using the existing topography of the land we worked with City staff and have researched three options for dealing with the storm water ponding; 1. West most pond site; engineering wise it is a volatile structure and least structurally sound because of being built on the side of a hill. Of the options, due to it's proximity to the creek it will also provide the least amount of filtering of the on site storm water discharge from the pond through the wetland before entering Bluff Creek. This pond would provide no treatment or control for the existing off site runoff from the railroad property to the South which is currently eroding two gullies across our site and into the wetland. 2. Moving the proposed ponding site as far out of the Bluff Creek Overlay as possible pushes the pond uphill constraining the available storage volume and yields less in positive control of storm water runoff rate and volume. The pond is proposed to be excavated as deep as possible given the water table of the wetland. This plan which reduces the available storage volume would require us to divert the existing water coming from the two points of the railroad property south of us directly into the wetland, hence not treating or controlling this storm water runoff prior to being dumped into the wetland. This is less than a good plan. 3. The best and most reasonable plan is to allow the storm water pond to be built at the lowest point on the property; this is where the majority of the on site water along with considerable water from the South currently flows. This proposed location uses the existing topography adjacent to the wetland to create a pond of a size that would meet the City and Watershed requirements for quality and rate control, Additionally, this would allow the water coming from the railroad property through the two existing gullies to be directed, treated, and controlled in the proposed pond before discharging to the wetland and Bluff Creek. In this proposal-75% of the pond will be located outside the BCOL. We are requesting a variance for the remaining portion of the pond that is proposed within the BCOL. We believe that within a couple of years that this pond would look like and take on the characteristics of the existing wetland/pond area directly adjacent to this same wetland complex to the North. Private entry road This site has prior approval on the entry to the property shown in the sketches and by the physical "curb cut" on the property. We examined the option of moving the entry of the road to coincide with intersection at the North end of the property. This is not a feasible location due to the high degree of sloping on that North section ofthe property, shown in the attached engineering drawing. The road plan as submitted utilizing the existing curb cut is what our plan is based on.