09-19-2002 Planning Commission Meeting

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Chuck Marohn,Pequot Lakes September 3, 2002 �..- Page 2 3. No roadway vertical grades are called out. But from the 10-foot contours, it appears the vertical grades of North Branch Trail and Pinekrist Trail should be acceptable. We do note, however, as is indicated by the ditch checks and silt fence along North Branch Trail where it comes into Township Road No. 11419th Avenue SW,that there may be some steeper grades and slopes that should be reviewed by the City in the field after initial grading for possible additional construction before final acceptance is made. 4. While it is difficult to determine as no vertical roadway grades are called out and only 10- foot contours are indicated, it does appear the sight distances at the Pinekrist Trail North Branch Trail-Outlot B; at the Pinekrist Trail-Township Road No. 11419th Avenue SW; and at the North Branch Trail-Township Road No. 11419th Avenue SW intersections should be acceptable. However, as a follow-up and somewhat related to our earlier comments in regards to the vertical grade of North Branch Trail where it comes into Township Road No. 11419th Avenue SW, the sight distance north and south along Township Road No. 11419th Avenue SW from North Branch Trail should be reviewed by the City in the field after initial grading for possible additional construction before final acceptance is made. 5. There are 15" CMP culverts shown at three locations. We did not check hydrology and hydraulic calculations as none were included nor did we calculate any ourselves to see if the 15" CMP size was appropriate. For residential development with grassed ditches, we would suspect that this size culvert should be appropriate. However, please note our following comments. The `hole' shown by the contours just north of the North Branch Trail-Township Road No. 11419th Avenue SW intersection appears to be a relatively significant local `hole'. The 15" CMP culverts under Pinekrist Trail and North Branch Trail may be acceptable for now,but depending on the drainage area to this hole and the amount of development within this drainage area, one or both of these culverts may need to be upsized. With 10-foot contours, it is difficult to determine drainage directions. However, at the Pinekrist Trail-North Branch Trail-Outlot B intersection, the grades suggest a slope to the south. Besides the east-west culvert on the north side of this intersection,there may need to be two north-south culverts installed under Pinekrist Trail with swales draining to the south along Outlot B or a temporary infiltration basin dished out within Outlot B. For residential development with grassed ditches, it generally is not a problem. However, there have been situations where a 2-foot deep roadside ditch at the low points in the road