Agenda - Public Works Committee - 03/31/2015

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Public Works Committee Meeting Date: 03/31/2015 Submitted For: Len Linton, Engineering/Public Works By: Len Linton, Engineering/Public Works Title: Consider the Surface Water Management Plan Update 5. 2. Purpose/Background: State Statute requires Cities to prepare a Surface Water Management Plan (SWMP). The City of Ramsey has prepared several plans since the law went into effect. The attached document represents the latest update to the Surface Water Management Plan for the City. The current plan was prepared in 2008 and was scheduled for updating in 2015. The Lower Rum River Watershed Management Organization (LRRWMO) adopted their Third Generation Plan in 2012 which triggered the need to update Ramsey's Surface Water Management Plan. The Minnesota Pollution Control agency issued a revised Municipal Separate Storm Sewer System (MS4) permit in 2013. The City applied to the LRRWMO for received an extension for updating the SWMP so that the revision would include the Third Generation and MS4 permit requirements. The MS4 permit requires that the City have controls in place for regulating the discharge of stormwater. These controls include the SWMP, City Code and Best Management Practices (BMPs) to guide development. The BMPs are collected in a document called a Surface Water Pollution Prevention Plan (SWPPP). The SWPPP is being updated. The updated SWPPP will be included in the final SWMP before it is adopted by City Council. The following paragraphs were in the case presented to the EPB. The Lower Rum River Watershed Management Organization (LRRWMO) adopted their Third Generation Rules in 2012. The state regulations require that all local Storm Water Management Plans be updated within 2 years of adoption of revised Watershed Management Organization Plans. The Minnesota Pollution Control Agency was in the process of revising the Permit for the Municipal Small Separate Stormsewer Systems (MS4) and the Construction Stormwater Permit when the LRRWMO plan was adopted. The Cities of Ramsey, Anoka and Andover all applied for an extension of the deadline from the LRRWMO for revising their SWMPs until after the MS4 Permit was adopted so that required ordinance changes could be made once instead of several times. The extensions were approved. The changes contained in the MS4 Permit, Construction Stormwater Permit and LRRWMO covered the following areas: 1. Lowering the size of a project requiring a permit from 5 acres to 1 acre. 2. Requiring infiltration on site of the first 1" of runoff from all new impervious surfaces. 3. Limiting discharge from the site for the 2 year, 10 year and 100 year storms to the existing rate for each storm. 4. Reducing the amount of Total Suspended Solids and Total Phosphorus in runoff leaving the site. These goals can be achieved through the following measures: 1. Construction of infiltration or water reuse practices on site such as infiltration trenches, rain gardens, tree trenches or water re -use practices. 2. Constructing detention facilities that retain the peak flow and discharge it at a slower rate. 3. Construction of wet ponds that provide adequate time for settling of the Total Suspended Solids and Total Phosphorus and prevent resuspension with the next storm event. Timeframe: