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Ms. Katie Larsen 03/29/2019 Page 2 Lyngblomsten Preliminary Plat Engineering Review The low floor/opening elevations need to be labeled on the grading plan. The EOF will need to be further reviewed once other comments are addressed. It appears the trail may be blocking the EOF from the pond and culvert should be considered under the trail. 2. The applicant shall call out the EOF elevations (with a flow arrows) on the grading plan for all catch basin low points. The EOF should be 1.0-foot below the lowest adjacent building opening elevation. EOF elevations have been added to each special low point area EOF elevations will be reviewed when low floor/opening information is added to the plan. 3. Building low floor elevations should be shown on the grading plan sheets. Building low floor elevations have been added to the grading plans. 4. The applicant should label the 10:1 safety bench on the proposed pond. 5. The applicant should provide proposed centerline street grades (either grading sheets, or in profile on street plan sheet). Profile sheets will be accomplished in the final plat phase. In the meantime, percent of slope along the gutter or centerline have been shown on the drawings 6. The SWPPP is being reviewed by the City’s Environmental Coordinator; below are our preliminary comments: a. The applicant should provide silt fence around the existing wetland. Silt fence has been provided. b. The applicant should provide silt fence along the project perimeter adjacent to Hodgson Road. Silt fence has been provided 7. The applicant should provide and label a maintenance access route to the outlet control structure. The access should be a minimum of 10-feet wide, 8.0% longitudinal slope, and 2.0% cross slope. A maintenance access route mas been provided to the pond. The maintenance route has been labeled accordingly. 8. The applicant should include riprap at storm sewer outfalls. The City’s standard detail for Rip Rap at outlets should be included in the plans. The city standard detail has been added to the set 9. The applicant should review the rear yard drainage of Lots 6-8. The current plan shows drainage onto private property. Proposed surface drainage needs to be directed westerly towards Wetland 1. Surface drainage has been diverted to the wetland 10. The applicant shall review the grades between Hodgson Road and the berms at the end of the private cul de sac. It appears that drainage is trapped in that area. The grading in this area has been reviewed and modified accordingly Two contours are shown on the grading plan between the berm and Hodgson Road. One contour is labeled with a drainage arrow flowing towards the berm. If there is a ditch being graded or connected too, it should be clear on the grading plan. In the future, the trail will be extended to the north, the grading should be representative of this. 11. The minimum allowable grade across turf areas and drainage swales is 2%. Considering the users of the homes, the driveways have been designed to each be at about 3° slope. Because the grades outside the building are 6 inches Upon further review the turf areas should be a minimum of 2% or greater to minimize the potential for standing water. 12. The grading plan needs to be adjusted at the southwest existing retaining wall. The grading plan has been adjusted 13. The applicant shall clearly label the top and bottom of the retaining wall along the pond. Retaining walls over 4 feet require a licensed engineering design and an approved fence. 14. The applicant has included the impervious surface area of the Hodgson turn lanes in the storm water calculations. However, they have not addressed how stormwater will be managed. There is no storm sewer system or ditch system shown, the applicant will need to coordinate the drainage plan with Anoka County also. Turn lane construction plans will be required with the final plat.