05/11/2016 P&Z Packet - Laserfiche WebLink

Home Search

Ms. Katie Larsen April 06, 2016 Page 2 STORMWATER MANAGEMENT The stormwater management for the proposed Watermark Development was reviewed against the proposed Northeast Drainage Area InfoSWMM model high water elevations from March 30, 2016 and enclosed (see Attachment 1). 1. Include water re -use system layout and water fountains in plans. The re -use pump stations should not be located near storm sewer outlets. 2. Normal and critical duration high water levels are provided (attached) — please review maximum water elevations versus proposed grading. The high water elevation may not encroach onto private property. 3. Stormwater modeling needs to be submitted based on the proposed phasing plan for development. 4. Emergency overflow elevations need to be shown on the plans. 5. Low floor elevations have been reviewed against the maximum high water elevations and structures with deficiencies in freeboard requirements are noted on redlined plans. 6. Many of the proposed ponds have more than four feet of bounce; ensure proposed plan species in this zone are tolerant of extended inundation. Plantings in this area may also require a full growing season at a moderated bounce levels to ensure establishment. 7. Drain tile lines need to be re-routed and all drainage rights must be maintained per Minnesota Statutes Chapter 103E. 8. Soil amendments for filtration at pond 300 to the adjacent wetland and pond 20 to outlot J. 9. It is recommended that rear yard filtration systems be considered. 10. A stormwater management plan has not been provided and will be required for final approval. 11. Provide details for outlet control structures and pond interconnections FLOODPLAIN The proposed project has been reviewed against the currently effective FEMA Flood Insurance Rate Maps, dated December 16, 2015, and we offer the following comments: 1. The project proposes fill of, and changes to, the effective FEMA floodplain boundaries and will require a Letter of Map Revision (LOMR) from FEMA. All existing floodplain shown on the property is approximate Zone A, however because the project is proposing to develop more than 5 acres, the developer will need to provide a detailed study for the Conditional Letter of Map Revision (CLOMR) request with the final plat submittal, which would include establishing base flood elevations for the site. 2. A copy of the CLOMR application should be submitted with the final plat application. 3. The City will not issue building permits for lots affected by floodplain without an approved LOMR. WETLANDS 1. The project proposes 4.432 acres of wetland fill and 5.022 acres of wetland excavation with on -site mitigation for wetland impacts. On -site mitigation is proposed to be completed by creating 13.012 acres of new wetland, 4.842 acres of restored wetland, and 13.115 acres of created upland buffer. (Impact/Mitigation calculations taken from the KA02029-82044dn in\Docs\20160516 Engineering Review Lino Lakes-Mattamy.docx