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,) .' ; question of envelopment I think, but I am not sure of the statement being made here wi1hout additional information being indicated. 6. Page 2, paragraph 2. Where did you get1he statement 1hat "The ratio for the Cherry Creek PMP study is "...roughly seven..."? From what you indicated earlier in this paragraph, I take it that this is the ratio of PMP to 100 year precipitation but I am not sure of this or what area size and duration (I assume it is 6- and or 24- durations and point data) your looking at for this . reference. You can check table 6 of the NWSSS report for likely much of the supporting data in this regard. However, you seem to question this factor as being extremely large and indicate the need to for justification. I see that Mr. Fenn ofNWS states in the NWSSS report on page 6, section 3, paragraph 2, the last sentence, that "the maximum point values at 6-, and 24- hours from this study exceed the largest I OO-year return period precipitation in the Cherry Creek Drainage by roughly seven times." Now from table 6 of the NWS&S work and what I read from Mr. Fenn's statement that this "seventimes" factor really refers to observed Cherry Creek storm depths divided by the I OO-year, 6 hour point frequency value. I get 24.0/3.45 = 6.96 which is close to "seven times. It looks like the NWSSS work, table 6 for PMP to 100-year point 6-hour comparison purposes is 21.1/3.45 or only a ratio of 6.12 but of course for this comparison the point PMP value is that associated with a critical PMP storm over the Cherry Creek basin having a critical storm area size of around 400 square miles. My point here is that this large ratio is really driven by observed precipitation and not the value ofPMP as you seem to state. That's the justification you seek in A W A's comment here. ~ Additional CWCB Summarv Comments: I believe that A W A has met the minimum requirements except that nothing is indicated regarding the review of the Antecedent Moisture Study of7/l5/l997 that was to be addressed under the Scope of Work. A rewrite of this task should be accomplish to better support and make A W A comments understandable. Task 2: Verification of the NWS HMR 52 Runs and Use of Grass: The information regarding the HMR 52 runs provided in both 1he text and Appendix B appears to have met the minimum Scope of Work requirements. For those unfamiliar with the input! output files shown in Appendix B, some addition explanation would be worthwhile. Information needs to be provided as to the "Use. of Grass" in this study. Task 3: Sensitivity Studv of variable im{lactinl!: Site-S{lecific PMP's: I am in agreement with much of what has been indicated by A W A under this task. A large portion of what has been reviewed by A W A is in present agreement with what forms the basis and serves as a foundation in the development ofPMP estimates. There are modifications and in some cases new worthwhile ideas and thoughts shown that I highly encourage A W A and others to further develop (isohyetal pattern development and orientation, and barrier effects). I hope that in coming months that A W A and associates will be able to develop a more thorough analysis of the information they have presented in certain areas of their investigations and be able to present at least a potential impact (flood flow) of these modifications to what is currently derived from use ofNWSSS results.