FLOOD02983 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I Mr. Ben Urbonas, P.E. Page Five December 14, 1977 Mr. Ben Urbonas, P.E. Page Six December 14, 1977 where the relief storm drain will discharge its flows. My general comments on damage specifically apply here, as does the decision not to combine irrigation and drainage flows in the canal. I assume both of these guidelines have been followed, but if they have not, this recommendation should be reviewed to determine if they have been met. can adequately handle the flows from upstream. If either of these questions are answered in the negative, then leaving the open channel sized to carry the 5-year frequency is unsatisfactory. In the event the questions are answered in the affirmative, the IO-year sizing of the open channel would not be a legal necessity but should be reconsidered based on reduction of flood damage. 4. Reach 1. 2. Reach 5. The alternates discussed and recommended in this reach appear to be legally satisfactory. The damage to the home west of Bemis Street as a result of these recommended improvements should be verified to assure the engineers that the home' will not suffer any increased damage as a result of the increased detention storage behind the railroad embankment, and as a result of the relocation of the City Ditch and the filling up of the vacated City Ditch. The alternates recommended in this Reach are legally satisfactory if the apartment-townhouse development is not exposed to damage in excess of historic levels by virtue of the suggested improvements. 3. Reaches 2, 3 and 4. The side channel spill detention facility recom- mended in the upper portion in Reach 4, from onsite observation, may cause damages in excess of historic levels to at least one, or possibly more, homes abutting ontq and being at the westerly end of the present park. It is unclear from the report whether this would occur if the suggested alternate was implemented and, there- fore, this question should be satisfactorily answered before pro- ceeding any further with this alternate. In regard to the open channel in the median of Sterne Parkway, it is clear that the Citv of Littleton has created some portion of the flooding problem by the use or allowing the use of inadequate culverts at the street crossings. At the very least, all culverts at street crossings should be increased to pass the 5-year storm since that is what the capacity of the open channel appears to be. These comments also apply to the proposed extension of Sterne Parkway. Since these culverts that pass only the 2-year frequency create flooding by themselves, they are legally unacceptable. Finally, at the very least, all commercial, industrial, and residential occupants of the defined flood plain of Little Creek should be notified that they are in the flood plain. If you have any further questions, or desire any comments on any other aspect of the report, please contact either Joe or myself. Very truly yours, p_~-urq/ ;?,/~ /_ Edward J. Krisor, Jr. EJK: sc The sizing of the open channel in the median of Sterne Parkway should be reviewed again based on the fact that comments on Page 37 of the report lead me to the conclusion that sizing the channel to the lO-year frequencv eliminates damage even from the lOO-year flood. Also, it is noted that in Reach 3 the natural channel in that por- tion of the Reach will carry the lO-year storm without damaging adjacent residences. It is unclear in the report whether or not the open channel in Reach 2 can adequately accocmodate the flows coming naturally from Reach 3 and also with the improvements up- stream of Reach 4 in Reach 5 whether the open channel in Reach 4 -A-IO-