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Planning Commission Case No.471-97: O'Neil Property March 28, 1997 Page 5 are typically placed in the buffer area since they need to be close to the wetland. They usually revegetate so they continue to provide a"natural"buffer for the wetland. Encroachment of buildings into buffer areas creates less problems than parking lots because the runoff is cleaner. Staff regards the encroachment of the theater building into the buffer as workable if the area between the building and the wetland is left natural, so the vegetation will continue to provide a filtering and screening effect. A portion of the restaurant development on Parcels A&B may be in the buffer, although the amount will not be known until we have a specific layout with the development stage plan. ■ Drainage The proposed drainage system is consistent with the City's local water management plan, and will provide the necessary water quality filtering before runoff enters the wetland. Increased flows into the wetland will increase water surface elevations by 0.2 feet in a 10 year storm, and 0.3 feet in a 100 year storm. The increased water elevation will not have a negative impact on adjacent structures or roads; the water will remain on the site. The City Engineer recommends that the existing 15" pipe from the wetland into the Long Lake Road storm sewer remain as is, since enlarging it would cause capacity problems downstream and there is enough room to store water in the wetland. There should not be any impacts to existing groundwater table, and little change in the current recharge potential of the area. An engineered drainage design would be submitted at the development plan stage. Residents south of the O'Neil property have expressed concerns that this development will increase existing problems with flooding in their backyards. The City Engineer reviewed this situation and responded that the localized flooding south of County Road H2 is not affected by the O'Neil property, even with development. Also, according to Al Sunderman, a groundwater specialist in the City Engineer's Office,there should not be any impacts to the existing groundwater table in the area. It is the City Engineer's view that flooding in the neighborhood is being caused by upstream drainage from the north side of Highway 10 overloading the existing storm drain system in the neighborhood. The size of the storm drains needs to be upgraded or a parallel line installed so water is diverted before it reaches the storm drain in County Road H2. • Soils The soils on the O'Neil property are classified as having moderate limitations, in the area proposed for development, and severe limitations where the wetland is located. According to the plan, "most development can occur without complex erosion or slope problems"in this category. Staff recommends that soil testing be done at the development plan stage only if determined necessary by the City Engineer. • Vegetation &Landscaping The applicant is proposing to retain the existing tree coverage outside of the developed area of the site. Staff is recommending a condition that the trees 10" in diameter or larger be inventoried at the development plan stage, and that they be preserved wherever possible. Protection of the tree coverage intended for preservation during construction would be a condition of approval. In the buffer area along County Road H2, the applicant is willing to either retain the oak woodland, supplement this area with additional tree plantings, or substitute berming and manicured landscaping, as the community desires. A decision on the type of treatment would be made at the development plan stage. The landscape plan • for the development portion of the site would also be submitted at the development plan stage.