2009-04-28_PWETC_AgendaPacket - Laserfiche WebLink

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1 L Introduction 2 One part of the City's Comprehensive Surface Water Management Plan (CSWMP), is for 3 staff to provide a brief annual report. to summarize development changes, capital 4 improvements, and other water management related issues that have occurred over the 5 past year. In the past, this has been completed as a part of the SWPPP Annual Report. In 6 the interest of providing a more in depth discussion of the storm water issues that staff 7 has worked through during the course of the year, we are providing this as a separate 8 document: This will allow us to include more information and. enable us to better plan 9 for future storm water needs. 10 City staff keeps track. of the majority of the rainfalls that occur within the City.. This is I l accomplished through a gauge at the Maintenance Building. We have included this I2 information at the end of this report. 13 The report includes the following sections; CSWMP Problem Area Updates, 2008 New 14 Problem Areas, 2008 City Projects, 2008 Redevelopment Projects, and Other Drainage 15 Concerns. 16 II, CSWMP Problem Area Updates 17 Five problem areas were identified as a part of the 2003 CSWMP. Over the past 4 years 18 we have been able to address some of these areas through additional study or construction 19 projects. Some of the issues that were identified have been resolved. while others have 20 developed new concerns. We now have nine problem areas. What follows is a summary 21 of the status of these problem areas. 22 A. Area 1- Avon- Brenner. 23 Over the years, the City has made a number of improvements in this area to address street 24 flooding and increase the pollutant removal efficiency within the Charlie Pond 25 subwatershed of Lake Owasso: Changes in subwatershed boundaries, the addition of the 26 Valley Park ponds, new outlets, and larger pipes have all played a role in improving the 27 drainage for the area. 28 As recently as 6 years ago there were I3 vacant lots in this neighborhood. In the last 6 29 years, 7 of these-lots have been developed as single family homes. 6 of these lots are 30 located along the south side of Brenner Avenue west of Millwood Avenue. As these lots 31 continue to be developed, renewed neighborhood concern has been expressed about the 32 need for additional storm water improvements for this subwatershed. One of these vacant 33 lots is between 812 and 800 Brenner Avenue and has a low area that drains into the 34 City's system. To determine the role that this lot plays in the updated overall storm water 35 system, a new XP-SWMM model was created by URS in 2006. 36 Action to date: 37 This analysis allowed us to evaluate the performance of the system during intense storm 38 events and. determine how incremental improvements would impact the elevation of 39 flooding within rear yards, low areas, and intersections in this neighborhood. As a result 40 of this analysis, the following improvements were constructed in 2007: 41 Brenner Street 42 Runoff from the wetland on the vacant lot west of 800 Brenner was redirected to 43 storm sewer which flows directly to Lake Owasso, allowing for additional capacity in City of Roseville 2008 Storm Water Anneal Report Page 2 of 14