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<br />the Probable Maximum Precipitation (PMP), Site Specific Study for Cherry Creek Reservoir" dated August 2003.
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<br />A W A approach vs. the NWS approach: Both approaches followed recognized PMP Procedures. The NWS Study
<br />started with the generalized PMP values from Hydro-Meteorological Reports (HMR). Their process used one regional
<br />storm and then used procedures to apply the generalized PMP values down in spatial scale to the specific watershed. The
<br />A W A approach started with observed rainfall data along the Front Range that were identified as the most extreme storms.
<br />A W A then applied the same PMP and methods and applied them to the study basin. The June 16, 1965 rainfall pattem
<br />graphic illustration on the previous page shows how A W A used GIS to transpose Colorado extreme storms into the basin.
<br />The red line in the graphic is the outline of the Cherry Creek Basin. The storms were moved into the Cherry Creek Basin
<br />and centered to allow for the most amount of rainfall to compute PMP estimates for the study. A W A also included an
<br />enveloping and smoothing process for mass storm curves that also ensures a safety factor.
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<br />CWCB project timeline: The following table represents the chronology of events and meetings that summarize
<br />participation in the scientific studies and issues surrounding Cherry Creek Reservoir. For the CWCB's study, completed
<br />in 2003, Applied Weather Associates was the study contractor. Larry Lang, CWCB Flood Protection Program Chief was
<br />the project manager, and the project administrator was Joe Busto, CWCB Flood Protection Program. Ross Williams of
<br />Applied Weather Associates provided administration support and Geographic Information Systems mapping for analysis.
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<br />CWCB Project Involvement, Meetin2s & Milestones DATE
<br />NWS completes Sit()- Specific PMP Study July 13, 1995
<br />Corps project scope meeting for EIS as part ofNEPA process in Aurora March 4,1997
<br />NWS responds to comments submitted by local governments/State of Colorado July 10, 1997
<br />NWS Antecedent Moisture Study Completed July 15, 1997
<br />State Officials/Project Advisory Committee Meeting June 28,1999
<br />NWS responds to comments March 5,1999
<br />Corps public presentations/meetings July 21,1999
<br />CWCB/Corps meeting August 20,1999
<br />CWCB - Project scope defined / Technical Meeting # 1 November 3, 1999
<br />CWCB - Project scope defined /Technical Meeting # 2 November 16, 1999
<br />CWCB - Project scope defined /Technical Meeting # 3 (NWS, Corps, State) December 13, 1999
<br />CWCB -Project scope defined/Tech Meeting # 4 (MOU abandoned review ofNWS PMP Study endorsed) January 5,2000
<br />Contractor - Cheryl Signs prepares SOW and RFP and selection process for the CWCB March 15,2000
<br />CWCB- Contract negotiations with A W A (successful bidder for the PMP Study January, 5 2001
<br />CWCB - A W A study project "Kick off' meeting February 2, 2001
<br />CWCB - A W A study project meeting March 15,2001
<br />CWCB - Contracted (Lou Schreiner-USBR, Gary Lewis-Parson's Engineering, Nolan Doesken-Colo. Climate Center) April 2, 2001
<br />CWCB - A W A study project meeting May 23, 2001
<br />CWCB - Freedom ofInformation Act request for NWS backup data used in original analysis August 8, 2001
<br />CWCB - A W A (Dr. Bob Jarrett, USGS) field tour for paleo-flood evidence in Cherry Creek Basin August 8, 2001
<br />CWCB - Project Meeting August 9, 2001
<br />CWCB - Progress Meeting with Corps Mike White October 11,2001
<br />CWCB - Letter to NWS Inviting NWS to attend project meetings October 22, 2001
<br />CWCB - Project Meeting November 1,2001
<br />CWCB -A WA Team Project Meeting December 19,2001
<br />CWCB - Letter to NWS Inviting NWS to attend project meetings January 14,2002
<br />CWCB - Project Meeting January 29, 2002
<br />CWCB - A W A Interim Report # 1 Completed/Project Meeting (Technical Review Panel comments submitted) February 19,2002
<br />CWCB - Draft contract for NWS meeting participation/technical review of A WA study idea abandoned March 2, 2002
<br />CWCB - Project Meeting (cancelled 5 foot snow storm) March 19,2002
<br />CWCB - A W A Interim Report # 2 Completed/Project Meeting (Technical Review Panel comments submitted) May 8, 2002
<br />CWCB - A W A addresses Interim Report # 2 Comments by TRP June 4,2002
<br />CWCB - CWCB staff present findings to sponsors (Aurora, Greenwood Village, Douglas & Arapahoe Counties) August 16,2002
<br />CWCB - CWCB staff present findings to Cheery Creek Basin Authoritv Annual Conference November 1,2002
<br />CWCB - Contract renegotiation and contract amendment January 5. 2003
<br />CWCB - First Final Project meeting (A WA results) April 2, 2003
<br />CWCB - Final Project Meeting (Final Technical Review Panel comments, Final NWS comments) June 19,2003
<br />CWCB - CWCB letter to Corps to use A W A results in Corps PMF study July 15,2003
<br />Corps - Response to CWCB agrees to use A W A results in PMF study August 4, 2003
<br />CWCB - Presentation of Final Report/Recommendations, approved By CWCB Members by a vote of7-0 September 22, 2003
<br />CWCB - A W A Final Report sent to communities, Corps, NWS, and state legislators and congressional delegation November 15,2003
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