2014-04-09 CC Packet - Laserfiche WebLink

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l emo 7. FEMA standards are that models use normal depth as the downstream boundary condition. The backwater condition from the receiving waters is then drawn in the FIS profile as a level line on the downstream end until it meets the modeled profile. Please use normal depth as the model boundary conditions, if practical. 8., There are a number of warning messages that appear when the model is run in XP -SWMM. Many of the conduit lengths are less than the default minimum conduit length parameter in the model. 9_ There are warning messages in the output file for storage nodes where the area decreases between stages. These nodes are SJ3BR3 060, SJ3MT 046, SJ3MT SJ3MT SJ3MT 099, SJ3P1 007 and SJ3P1 008_ Please review and revise if necessary. 10. Please specify which vertical datum (NGVD29 or NAVD88) was used for the model input data and results. 11. Please note that the model will have to be checked for map-model agreement for water surface elevations before incorporation into the final maps. The model documentation indicates that the XP- SWMM results do not match the InfoSWMM elevations used to generate the floodplains. The final model results (whether XP -SWMM or EPA -SWMM) must match the mapped floodplain elevations. 12. The current Zone A floodplain mapping does not extend all the way downstream to Peltier Lake. As the differences in elevation between the Zone A modeling and the effective elevations appear to be significant, the tie-in point may be Peltier Lake. 13. For purposes of the FIS, the modeled and mapped lengths along the profile baseline must agree within 25 feet. Calculated link lengths from GIS were compared to the modeled link lengths, and the following links had length discrepancies that could not be explained by the presence of storage areas: CJ3MT 013, CJ3MT 014, CJ3MT 001, CJ3MT 029, CJ3P1 003 and CJ3MT 012. (Typically, XP -§WMM storage areas along the profile baseline are shown in profile as areas of constant water surface elevation; they are measured from the map as their length is not represented in the model; these areas are added manually to the profile after the model results are exported.) 14. Please verify the link length of CJ3BEL 013, as the model data, GIS attributes, and calculated GIS lengths all disagree. 15. There are areas of disconnected flooding: two near node SJ3P1 007, one near node J3P1 006, one near node J3MT 017, three near SJ3P1 016, one near node SJ3MT 021, one near J3MT 012, one near SJ3MT 013 and one near SJ3MT 036_ Please clarify whether these should be shown as separate ponding areas with stillwater elevations, connected to the floodplain, shown as a separate profile and connected with ditches/culverts that contain the 100 -yr flood, or deleted entirety. 16. There is a gap in the flooding along the link between J3MT 029 and J3MT 030 that does not appear to be due to a culvert, please adjust the delineation. 17. Please submit the floodplain and floodway delineations on a topographic workmap with the vertical datum used, signed by a professional engineer. DIEM AM ero.�uw. sincc,e. Documentl