Agenda - Council - 10/27/2015 - Laserfiche WebLink

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alleviate this problem in Pond P21208, we recommend constructing an outlet culvert outlet under 161st Avenue may adequately address the problem flooding experienced there. The problem in Pond P21210, which is upstream from the residential nuisance flooding area, may be corrected by either expanding the infiltration basin storage or by re -grading the emergency overflow spillway at a lower elevation to alleviate the potential flooding threat. We recommend that the undeveloped part of the WMISS watershed, lying immediately west of the COR, treated in a similar fashion as the COR. If a separate outfall can be created for this area, it could work in an almost identical fashion. If a separate outfall cannot be obtained, a large regional pond network is recommended. If the ponding alternative is taken, the regional pond network would need to store 100 percent of the runoff at a safe level prior to out letting into the COR system. This would ensure that the COR is not threatened by continued development upstream. Finally, the Highway 10 corridor is appears to have some pond overflow problems that are only associated with using the ditches as storage. We believe that the best fmancial and hydrological solution to alleviate these problem areas is to coordinate with MNDOT on any future TH 10 improvements. Any improvements to TH 10 are likely to involve new corridor stormwater management and funding. General Figures 28 through 30 are typical SSA output files for a single pipe/pond corridor. These are intended to illustrate the output potential of the model and software. If similar output files were created for every aspect of the entire system, this report would be too cumbersome. The 2008 Plan provided Geographic Information System (GIS) data that allows the City to model virtually any pipe, pond or ditch within Ramsey. It is extremely important that each area be re-evaluated at the time of final design to confirm the criteria used in this study and to make any changes that a proposed development may dictate. Special consideration must be given to areas that develop differently than shown in the Comprehensive SWMP, especially when a higher runoff coefficient is likely to result from development. All storm sewer facilities, especially those conveying large quantities of water at high velocities, should be designed with efficient hydraulic characteristics. Special attention should be given during final design to those lines that have extreme slopes and create high hydraulic heads. The Best Management Practices (BMPs) recommended by the MPCA and adopted by the City shall be followed as development or redevelopment occurs. C. Recommendations The following recommendations are presented for the City Council's consideration based upon the data compiled in this report: 1. The SWMP as presented herein will be adopted by the City of Ramsey. 2. The recommended corrections for flood prone areas will be made as described herein and made a part of the storm water management system, where feasible. 3. Standard review procedures will be established, where feasible, to ensure all development within the City is in compliance with proper erosion control practices. Section X October 21, 2015 Page 69