Agenda - Planning Commission - 10/06/2016

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Review File:Brookfield 8th Addition Preliminary Plat Exhibits Engineering Review September 16, 2016 Page 3 of 4 C 1.2 1. Provide minimum 0.1 foot drop through each storm structure. 2. Revise access drive to existing lift station. Provide minimum 16 foot wide paved access drives to both east and west sides of lift station with 10 foot clearance from infrastructure. 3. Nyloplast catch basin for lift station is not acceptable. Storm sewer structures for City facilities must be concrete. 4. The lift station detail does not provide positive drainage away from the structure. The slabs must be raised to provide positive drainage to the street or a larger easement must be provided on Lot 1, Block 1 so that drainage will flow to the north. C 2.1 1. This sheet must be placed after sheet C2.2 in the set. 2. This sheet is missing key components required by the MPCA Construction Stormwater Permit. Review the permit and add the required elements. 3. Add a note to the inspection section: "Daily (after rain) and weekly inspection logs must be emailed to the City. The complete logs must be submitted to the City prior to finalizing the project. The City must grant approval for submittal of the Notice of Termination for the project." C 2.2 1. This sheet must be placed before sheet C2.1 in the set. 2. Columns for quantities and unit of measurement must be added to the table. 3. The MPCA will be assigning a TMDL for dissolved oxygen to Trott Brook. Information in the SWPPP will need to be revised to reflect this change. Detail Sheets 1. Add typical section for 1681h Circle with dimensions, grades, and pavement section. 2. Remove detail STO-10. It is for larger pipe than is used on this project. 3. Remove Nyoplast 30" drain basin detail (see note for sheet C 12). 4. Add the MnDOT 5 sheet detail set for Pedestrian Ramps. A ramp will be required where the trail meets the street. Stormwater Calculations A stormwater summary report was provided. The elevations on the grading plan do not match the Hydrocad Model. Drainage area 3 empties into an existing wetland that was modeled with the previous phase of Brookfield. The model must be updated to reflect the runoff from the back of the houses. The LRRWMO requires volume reduction (infiltration) on all projects. The benefit from the off-line filtration system is not called out in the report. The City uses the Walker spreadsheet to check for water quality treatment volume. Our analysis is not complete at this time. We will provide the results of our analysis when it is complete.