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Ben Urbonas - Urban Drainage and Flood Control District Paula Lundquist - Jefferson County Bob Deeds - City of Littleton Larry Lang - Colorado Water Conservation Board Bruce Buttner - Olsson Associates David Krickbaum - Olsson Associates 6. There is an existing detention pond west of Kipling Street, between Ken Caryl Avenue and Chatfield. Paula will look for plans that will identify the location of the outfall for this pond. 7, The next meeting will be on March 31, 2004, 9:00 at Olsson Associates' office. Alternatives, costs and pros and cons of the alternatives will be discusses, I I I I I I I I I . I I I I I I . I I 0\. Massey Draw and SJCD Update Project Meeting Minutes March 2, 2004 Page 2 of 2 OLSSON ASSOCIATES EN G IN E E RS' PLAN N E RS' SClE NTIS T5' SURVEYORS MEETING MINUTES 4. Larry Lange noted that a new bridge, downstream of C-470, has been identified in the Chatfield Recreation Plan. The design flows for the new bridge have been based on the size of the existing culverts under C-470. He asked what the flows will be from the masterplan update. Based on the Urban Drainage and Flood Control District (UDFCD) 1985 memorandum, the flows at C-470 will be about 3000 cfs. A copy of the memorandum was given to Larry. 143 Union Blvd. Suite 700 Lakewood, CO 80228720-962-6072 Massey Draw and SJCD (South) Update OA Project No. 02-2003-1321 March 2, 2004 5. Problem areas along the study reaches were identified and discussed. Generally, the problems that have been observed include channel and bank erosion. Low flow grade control will be evaluated in these areas. Massey Draw and the North Tributary of Massey Draw may not have adequate capacity downstream of Carr Street. Opportunities for regional detention will be explored to attenuate the flows downstream of Carr Street. Attendees: Discussion Items: 1. Olsson Associates (OA) received an e-mail from Larry Mugler, in response to the February 18, 2004 meeting minutes, encouraging the use of the future land use map currently adopted by the county. It was confirmed by the sponsors that that is the intent. Although the community plan for South Jefferson County will be updated later this year, the study area is essentially built out and the changes to the community plan are anticipated to be minor, with insignificant impacts on the hydrology. cc: Attendees via e-mail Russ Clayshulte via e-mail Paul Winkle Kent Wiley Larry Lang via e-mail Gene Reetz John Liou Bill Kieck via e-mail Melissa Chew via e-mail Tim Carey via e-mail Larry Mugler via e-mail Rick McLoud via e-mail Scott Franklin via e-mail Sean Warren via e-mail Justin Werdel via e-mail Alecia Cope via e-mail 2, The discrepancies between the watershed areas from the original masterplan and the areas delineated by OA for the update have been reconciled, The original masterplan did not include the North Tributary for SJCD (South), whereas the update does, When this is taken into account, OA's area for SJCD (South) is 3% greater than that used in the original masterplan. OA's delineation of the North Tributary for Massey Draw is slightly different than that used in the original masterplan, Therefore, OA's area for the north tributary is 16% greater than that used in the original masterplan, however, the total area for Massey Draw is 2% smaller. Ben asked that these differences be noted in the report. A table was distributed comparing the areas from the original masterplan and the update. 3. The hydrologic modeling is progressing. Ben suggested that the impervious values could be reduced. Commercial and industrial area could be reduced from 95 to 85%, multi-family could be reduced form 75 to 70%, and open space areas could be reduced to 0%. OA and Ben will meet separately to review and discuss calibration of the model to approximate the discharges from the original master plan,