Consider the Surface Water Management Plan Update

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.

 

The SWMP was reviewed by the EPB at their March meeting.  They were in general agreement with the content of the SWMP. The  SWMP will be reviewed by the Public Works Committee tonight.  It will be the subject of a Public Hearing before  the Planning Commission at their April meeting.with particular emphasis on the changes to City Code related to land use.  The Public Hearing is required when considering changes to City Code.  The SWMP will be brought to the City Council at the April 21 meeting for review and approval.

The plan will we sent to the LRRWMO and the Metropolitan Council for concurrent review the first week of May.  The LRRWMO has 60 days to review and approve the plan, the Metropolitan Council has 45 days for review.
The document will be updated as necessary after the comments are received then brought back to City Council for adoption.  This is anticipated to be the first meeting in August.

The City of Ramsey is bordered on the east by the Rum River and on the south by the Mississippi River.  The City has many wetlands, lakes and streams with in it's borders. Managing the discharge of storm water from developed sites is a critical component of preserving the water quality of the wetlands, lakes, streams and rivers in and adjacent to the City.  The Surface Water Management Plan provides a frame work for allowing development while maintaining surface water quality.

The changes to the document include:

• Updating City Code references to the current system
• Updating the Stormwater management requirements for new construction
  • Infiltrate first 1” of runoff from new impervious surfaces
  • Provide rate control and water quality treatment for the 2, 10 and 100 year return events.
  • Provide reduction for Total Suspended Solids and Total Phosphorus concentrations in stormwater leaving the site.
  • Update the reference storms to use the Atlas 14 publication.  The LRRWMO adopted use of the Atlas 14 and required the member cities to adopt this standard.
• Remove references to wetland buffers for new construction.  The City completed a Wetland Management Plan with the 2008 SWMP.  The implementation of the Wetland Management Plan was postponed by City Council Action.
• Update the Stormwater Models to include developments constructed after 2008 and use Atlas 14 for rainfall events.
• Update the tables and figures to include the new model results.

Staff has performed the update to the plan as part of their normal duties.   The Stormwater Utility Fund covers part of staff salaries. The  plan lists Capital Improvement Projects that will need to be brought back individually for review and approval.

Staff recommends the Committee approve the Surface Water Management Plan and forward it to City Council for approval.

Motion to approve the Surface Water Management Plan and forward it to City Council for approval.