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Mr. Scott Harlicker August 9, 2001 Page Four preclude access to the pond since there is no way for a small child to exit from the pond. We also question how maintenance will be accomplished in this pond since the double retaining wall around the entire perimeter seems to preclude maintenance access to the pond itself or the area between the two retaining walls. We question the construction material for these retaining walls. The normal water level in all these ponds would be at the base of the lowest retaining wall. The high water level in these ponds would overtop the lowest retaining wall. It is our experience that modular block walls will not withstand exposure to this type of water. Are these walls to be poured in place, or will some other measure be taken to counteract the exposure to water? 3. The drainage pond on the west side of Tyler Street also has a double retaining wall around its entire perimeter. There is no outlet shown from the pond nor was this area included in the drainage calculations. Also, there is no way possible to build this pond as shown on the grading plan. There is a grading difference of over ten feet across this pond. Plus, it is built immediately adjacent to an existing wetland. Either one side of the retaining wall • is ten feet above natural ground, or the other side is 16 feet into the ground. 4. We still question the overall storm drainage design for this development. As I have indicated in my past memos, when the ponds reach the hundred-year flood elevation of 887.3, there will be a number of catchbasins in this system where water will be surcharged to within one foot of the casting. As you are aware, in all developments we require an emergency overflow route to be provided so that in the event of a larger frequency storm or back-to-back storms the route for stormwater flow can be determined such that no buildings will be endangered. In this development, if the emergency overflow route needs to be utilized because of a larger frequency storm or back-to-back storms, a major portion of the roadway system will be flooded and access may actually be cut off to the eastern part of the development. The attached drawing indicates the area according to the grading/drainage plan that would be flooded in the event that the emergency overflow route needs to be utilized. C. Utility Issues 1. No design analysis has been provided to indicate to determine whether an eight- inch water main loop through the development can deliver sufficient water necessary for domestic consumption and fire fighting capabilities. In addition to the water main loop shown through the public street area, additional water main loops need to be provided through the buildings themselves in order to strategically place hydrants for fire fighting capabilities throughout the development. • Howarc R. Green Corn pang CONSULTING ENGINEERS