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Ms. Michele McPherson • July 19, 2001 Page Two • The main entrance into this development off of Tyler Street should have a full median to prohibit left turns out of Outlot C. The traffic analysis indicates that 175 feet will be necessary for cars to queue up for left turn movements at peak times. The intersection should have 20 feet minimum width coming into the project and a left turn and right turn straight-through combination exiting the project. The left turn should line up opposite the left turn out of the North Star Corridor parking lot. • It is questionable whether or not the public square "round-about" just into the project should be allowed in this area given the relatively high volumes of traffic that will likely want to use this intersection. We believe this "round-about" will cause a major traffic concern. • At this point, there has been no detailed discussion with the developers relative to the width of the public roads internal to the project. Obviously; they would like them as narrow as possible to help to build the image they are trying to portray. From the City's standpoint, we need them wide enough to operate efficiently and safely for the traffic movements anticipated. B. Drainage • No revised drainage plans have been submitted. The last drainage plans we reviewed were dated March 13, 2001. At that point in time, we questioned some • of the calculations as being too conservative in the amount of runoff anticipated. We also questioned whether or not there was any runoff from the perimeter of the site. Currently, there is no accounting for runoff that may drain into the site. Revised drainage calculations need to be submitted, reviewed, and approved. • The current drainage system as laid out on the preliminary grading plan does not allow much room for error between working or isolated flooding at various points throughout the development. For instance, the westerly holding pond has a high water level of approximately 888.3. There are numerous catch basins located throughout the site that are literally inches above this elevation, which means in the hundred-year rainfall event, not only the pond will be full, but also much of the storm drainage system will be full to within inches of the catch basin grate. If the drainage calculations are off slightly or the storm is slightly more severe than a hundred-year event, water could be forced out of the catch basins at various locations throughout the site. • Both retention ponds shown in the development would currently require fencing according to City policy. The westerly pond is shown to have a double-tiered retaining wall on two sides and a triple-tiered retaining wall on the other two sides. The easterly pond is shown to have a double-tiered retaining wall around the south, east, and west sides and a single-tiered retaining wall along the north side. By City policy, if there is not a reasonable way for someone to get out of the ponding area, the area must be fenced. • There are several places throughout this development where additional storm sewer should be provided to eliminate storm water from running off of the sites • onto the public streets. Howarc R. Green Conoany 0:\PROJ\812620J_Elk River Station\0240\LtTVElTtprignn.egGINEERS