Phase A - Alternatives Analysis Report - Urban Drainage and Flood ...

PHASE A – ALTERNATIVES ANALYSIS REPORTMajor Drainageway Planning Update for Hidden Lake-Bates LakeMeeting MinutesHidden Lake – Bates LakeMajor Drainageway Planning UpdateWednesday April 23, 2008, 10:30am – 12:00 pm at UDFCDAttendees:Ken MacKenzie UDFCD 303-455-6277 kam@udfcd.orgShea Thomas UDFCD 303-455-6277 sthomas@udfcd.orgBesharah Najjar Adams County 303-453-8770 bnajjar@co.adams.co.usGeorgia Simpson City of Arvada 720-898-7646 gsimpson@arvada.orgJohn Burke City of Westminster 303-430-2400 x2126 jburke@ci.westminster.co.usRobert Krehbiel Matrix Design Group 303-572-0200 robertk@matrixdesigngroup.comTim Fairbank Matrix Design Group 303-572-0200 tim_fairbank@matrixdesigngroup.comWilson Wheeler Matrix Design Group 303-572-0200 wilson_wheeler@matrixdesigngroup.comJenn Newby Matrix Design Group 303-572-0200 jennifer_newby@matrixdesigngroup.com1. PurposeKick-off meeting and determine the additional information needed to start the project.2. Project Schedule – Compressed to 7 monthsA project schedule was presented at the meeting that compresses the project into 7 months and reduces thereview periods to two weeks and allows one month to select the preferred alternative.a. May 20 – Baseline Hydrology Reportb. June 11 – Benefit-Cost Calculationsc. June 18 – Draft Phase A Reportd. July 2 – Comments Duee. July 18 – Final Phase A Reportf. July 25 – Public Meetingg. August 18 – Select Preferred Alternativeh. October 16 – Draft Phase B Reporti. October 30 – Comments Duej. November 14 – Final Phase B Reportk. November 19 – Public Meeting4. Hydrologya. Impervious values for land use will be taken from the UDFCD criteria manual. More detailed correlationof other land use types to imperviousness will require review by the District.b. Sub-Basin Size (90-130 acre goal). Areas slightly larger than 130Ac are ok. If areas less than 90Ac areused, the C T , C P and Horton’s coefficients will need to be calibrated so the flows are not underestimated.c. Sub-Basins and design points will be renumbered for the study. A table will be developed that relates thenew design points to the design points in the 1975 study for comparison of the hydrology.d. Topography. Confirm that all elevation are on NAVD ’88. (Westminster and Adams County may be onNGVD ’29 and will need conversion.5. Opportunities – Constraints Mappinga. Known Drainage Issues or Flooding Problemsi. RTD Gold Lineii. Grace Church Driveway Culvertiii. Sheridan Culvertiv. CLOMR on Hidden Lakev. Alternative to Sheridan & Wellington Proposed Detention6. Public Involvementa. A project website will be set up before the next meeting.b. Public meetings will be held after the Draft Phase A report is submitted and after the Draft Phase B reportis submitted.c. The website can be hosted by UDFCD or Matrix.d. Website will contain a list of contacts, meeting minutes, maps, project description, schedule, etc.e. Website will remain through project completion and a few months beyond.7. Next MeetingThe next progress meeting is Monday May 19 th at 2:30 PM.8. Actions Itemsa. UDFCD will look into the existence of an agreement between UDFCD and the private owners ofHidden Lake regarding flood storage.b. UDFCD will look into the possibility of modeling privately owned detention basins if there is anoperational agreement between the private owner and the local government.c. Data collection per the following list:3. Additional Information Neededa. Previous Studies:i. Phase A Report Major Drainageway Planning Study, 1975 by Hydro-Triad (UDFCD)b. Crestview Water & Sanitation District contact information for the spillway design (Westminster)c. Storm infrastructure (Arvada & Adams Co.)d. Parcel data (Westminster & Adams Co.)e. Future land use (Adams Co.)f. 2007 Aerial imagery (UDFCD)g. 2-foot contour topography (Arvada & Adams Co.)h. Digital Floodplain Data (UDFCD)i. Soils Information (NRCS)j. CUHP/UDSWM Models from Phase B Report (UDFCD)k. Storage-Discharge relationship for Hidden Lake after spillway modifications (UDFCD)