Drainage Analysis. Appendix F

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1 Drainage Analysis Appendix F

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13 Golden View Drive Elizabeth Street LMORE CREEK Ricky Road Rabbit Creek Road LITTLE RABBIT CREEK East 156th Avenue MOA Project # Golden View Drive Intersection & Safety Upgrades ³ Bridgeview Drive NORTH BRANCH SOUTH FORK LITTLE RABBIT CREEK East 162nd Avenue East 164th Avenue SOUTH BRANCH SOUTH FORK LITTLE RABBIT CREEK Prominence Pointe Drive Ransom Ridge Road East 172nd Avenue Kallander Avenue NORTH BRANCH LITTLE SURVIVAL CREEK Bluebell Drive SOUTH BRANCH LITTLE SURVIVAL CREEK LITTLE SURVIVAL CREEK SOUTH FORK LITLE SURVIVAL CREEK Legend Stream POTTER BRANCH Romania Drive Bulgaria Drive Project Area Model Basin Impervious Area Existing Impervious Area per Model Basin Draft Design Study Report March

14 Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

15 Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

16 Design Rainfall Hyetograph SCS Type 1 Base Storm 1 Factor 2 Total 1 year 24 hour year 24 hour year 10 year Time (hr) 3 P t /P 24 Total Rainfall Total Rainfall (hr) (in) (in/period) (in) (in/period) Table 6-1, Watershed Management Services Drainage Design Guidelines, March Figure 2-2, Municipality of Anchorage Design Criteria Manual, January Table Applied Hydrology, Chow/Maidment/Mays, Rainfall (in) year 24 hour 10 year 24 hour Time (hr) Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

17 Subcatchment Summary - SCS Input Parameters Area (AC) % imp Impervious fraction SCS (89, 91) Pervious fraction Landscaped SCS (86, 89) Pervious fraction Wetland SCS (30, 30) Pervious Fraction Vegetated Upland SCS (70, 77) Sum check (1.00) Impervious Area Hydrologic Soil Group Curve Number Project Outfalls B % C B % C B % D B % C B % D B % C B % C B % C B % D B % C B % C B % C B % C/D B % C B % D B % C/D B % D B % C B % C B % C/D B % C B % C B % C B % C Lag Time (min) Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

18 Subcatchment Summary - Peak Runoff Results Existing Conditions Subcatchment Area 1-yr 24-hr 10-yr 24-hr UNIT (Acre) (cfs) (cfs/ac) (cfs) (cfs/ac) B B B B B B B B B B B B B B B B B B B B B B B B Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

19 Existing Time of Concentration Calculations Basin Characteristics Sheet Flow Undeveloped Shallow Ditch Shallow Basin ID area acres Rainfall Intensity Composite T c (min) length (ft) slope % n T t (min) check length nl/s^0.5<100 length (ft) slope % k T t (min) length (ft) slope % k T t (min) B % % % B % % % B % % % B % % % B % % % B % % % B % % % B % % % B % % B % % % B % % % B % % B % % % B % % % B % % % B % % % B % % % B % % % B % % % B % % % B % % % B % % % B % % B % % Pipe Channel Curb Shallow Basin ID length (ft) slope % n hydraulic radius, R (ft) T t (min) length (ft) slope % k T t (min) B % B % B % B % B % B B % B B % B B B B % B B B B B % - - B B B B B B Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

20 Golden View Drive Elizabeth Street ELMORE CREEK Rabbit Creek Road LITTLE RABBIT CREEK MOA Project # Golden View Drive Intersection & Safety Upgrades ³ Ricky Road East 156th Avenue Bridgeview Drive NORTH BRANCH SOUTH FORK LITTLE RABBIT CREEK East 162nd Avenue East 164th Avenue SOUTH BRANCH SOUTH FORK LITTLE RABBIT CREEK Prominence Pointe Drive Ransom Ridge Road East 172nd Avenue NORTH BRANCH LITTLE SURVIVAL CREEK Kallander Avenue Bluebell Drive SOUTH BRANCH LITTLE SURVIVAL CREEK LITTLE SURVIVAL CREEK SOUTH FORK LITLE SURVIVAL CREEK Legend Storm Pipe & Flow Direction Culvert & Flow Direction Open Channel & Flow Direction POTTER BRANCH Romania Drive Stream Project Area Proposed Drainage Map Bulgaria Drive Draft Design Study Report March

21 Subcatchment Summary - SCS Input Parameters Proposed Conditions Project Outfalls Area (AC) % imp Impervious fraction SCS (89, 91) Pervious fraction Landscaped SCS (86, 89) Pervious fraction Wetland SCS (30, 30) Pervious Fraction Vegetated Upland SCS (70, 77) Sum check (1.00) Impervious Area (AC) Hydrologic Soil Group Curve Number B % C B % C B % D B % C B % D B % C B % C B % C B % D B % C B % C B % C B % C/D B % C B % D B % C/D B % D B % C B % C B % C B % C B % D B % C B % C B % D B % C B % D B % D B % D B % D B % C/D B % C B % C B % C B % C Lag Time (min) Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

22 Subcatchment Summary - Peak Runoff Results Proposed Conditions Subcatchment Area 1-yr 24-hr 10-yr 24-hr UNIT (Acre) (cfs) (cfs/ac) (cfs) (cfs/ac) B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

23 Proposed Time of Concentration Calculations Basin Characteristics sheet undeveloped shallow Basin ID area acres Rainfall Intensity Composite T c (min) length (ft) slope % n T t (min) check length nl/s^0.5<100 length (ft) slope % k T t (min) B % % B % % B % % B % % B % % B % % B % % B % % B % B % % B % % B % % B % % B % % B % % B % % B % % B % % B % % B % B % B % B % B % B % B % B % B % B % B % B % % B % % B % % B % % B % % Golden View Drive Intersection and Safety Improvements MOA Project No February 2010

24 Proposed Time of Concentration Calculations ditch shallow curb shallow pipe channel hydraulic Basin ID length (ft) slope % k T t (min) length (ft) slope % k T t (min) length (ft) slope % n radius, R (ft) T t (min) B % % B % % B % % B % % B % % B % B % % B % B % % B % B % B B % % B % B % B % B % B % % B % B % % B % % B % % B % % B % % B % % B % % B % % B % % B % % B % % B % B % B % B B Golden View Drive Intersection and Safety Improvements MOA Project No February 2010