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Mr. Steve Wensman • February 24, 2000 Page Two • The internal street has a portion of street grade near the cul-de-sac that is approximately seven percent. This is a relatively steep grade for a business park development. However, it does fall within acceptable range provided in the City ordinance. • At this point, no drainage calculations have been submitted. These will need to be submitted, reviewed, and approved prior to final approval of this development. The preliminary grading plan does indicate that each individual lot will have a pond on it. We assume that these ponds will be sized for both quality control and rate control down to an existing condition discharge. The ponds are shown to discharge either into the proposed storm sewer along CSAH 12 or the proposed storm sewer along Tyler Street. The developer should work with the City and County to ensure that provisions are made in the necessary manhole structures to provide for these connections so that street disruption is not necessary in the future. There is a portion of the internal street and the area north of the street that is proposed to discharge to the existing ditch along CSAH 13. The run off from the portion of the street that flows this direction should be routed through the pond prior to discharge. In the future, we anticipate that CSAH 13 will be changed to an urban section instead of a rural section and this drainage will have to be accounted for in the road design. • • The preliminary plat should be provided with larger utility and drainage easements as needed for the sanitary sewer and watermain which fall outside the road right-of-way. C. Preliminary Sanitary Sewer and Watermain Plan • Sanitary sewer is proposed to be provided from the line in Tyler Street. The extension of the lateral into this plat crosses a tip of private property as it leaves Tyler Street. It will be necessary to get an easement from the owner in favor of the City of Elk River, or realign the sewer route to stay on the plat. • Watermain is proposed to be looped from the existing watermain in CSAH 12 at the east end of the plat. As is the Elk River Municipal Utilities policy, there will need to be a valve at each end of the watermain loop that falls outside of the street right-of- way and the pipe material will need to be HDPE. • Drainage and utility easements should be provided on the preliminary plat to encompass the necessary pond areas for each lot. Based on the zoning and the drainage requirement that the ponds not discharge at a higher rate than the preexisting rate. In the future, when development plans come forward for each of the lots consideration can be given to moving the ponds to a different location, at which time the City would vacate the given drainage and utility easements in exchange for different drainage and utility easements. • O:\PROJ\809220j\0240\Itr 2-24-00 SWensman.doc Howarc R. Green Company CONSULTING ENGINEERS