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HDR Presentation - StormW MgtCity of Dubuque City Council Working Session July 23, 2001 Storm Water Management Master Plan Preliminary Findings Presentation Outline Storm Water Management Overview Project Background Project Approach Project Goals Project Methodologies Alternative Selection Criteria North Fork Catfish Creek Drainage Basin Bee Branch Drainage Basin Possible Funding Sources Hydrologic Cycle Water Transported Ocean- Atmosphere · Precipitation · Runoff · Evaporation · Transpiration · Infiltration · Groundwater - Land - Ocean Storm Water Concepts Flow = A Rate in Cubic Feet Per Second (cfs) Velocity = Speed in Feet Per Second (fps) Losses = Rainfall- Runoff Storage = A Volume in Acre Feet (AF) (1 AF = 43,560 cu. ft.) Detention Retention Storm Characteristics: Intensity, Duration, Distribution, Movement, Reoccurrence Tools to Manage Storm Water Runoff Reduction · Infiltration Control · Restrict Development Timing Changes · Targeted Maintenance · Channel Improvements Storage · Detention · Retention Increase Capacity · Rainfall · Land Use · Physical Features Master Planning Process Input · Selection Criteria · Runoff rate · Geometry · Flooding Damages · Roadway Overtopping · Conveyance · Storage · Non-structural · Runoff rate · Volume Runoff · Water surface elevations · Depths · Flooding Limits · Violations Output · Phasing/ Sequencing · Capital Improvements Program · PrioritiZation · Funding Requirements Preliminary Policies Protect for Frequent Events or Rare Events Protect Only Large Basins or Small Ones Too Pass Problems Downstream or Solve Upstream Uniform Standards or Regionally Varied Uniform Maintenance or Targets Areas Retention or Detention Centralize or Decentralize Facilities Publicly or Privately Owned/Maintained Restrict or Encourage Development Include Erosion Control Practices Impose Water Quality Standards Public or Private Financing Project Background October 1998 City Selects HDR December 2000 HDR Completes Draft North Fork Master Plan April 2000 HDR Begins Master Plan May 2001 HDR Completes~ Draft Bee Branch Master Plan Project Approach ?OLICY ADMINISTRATIVE TECHNICAL LAND USE USER BASED BONDING MANUAL CRITERIA STANDARDS TECHNOLOGIES METHODOLOGIES WATER i G.I.S. MASTER PLAN MAJOR WATERSHEDS G.I.S. COMPUTER MODELS STORM WATER UT1LITY IMPLEMENTATION PERMITTING FEES PLAN DETENTION BANKING CAPITAL IMPROVEMENTS PROGRAM Project Goals Determine capacity of existing drainage system for ultimate development Develop hydraulic models on North Fork Catfish Creek and Bee Branch Identify problem areas Develop improvement plans for specific problem areas Address water quality in a qualitative nature by developing a list of possible Best Management Practices (BMPs) Identify potential funding sources for improvement plans Recommend required changes to storm water ordinance Develop preliminary policies to address storm water issues Develop preliminary drainage standards/criteria manual 10 Project Methodologies Ultimate Landuse Development HEC-HMS Hydrologic Model HEC-RAS and XP-SWMM Hydraulic Models Recommended Water Quality Best Management Practices (BMPs) Recommended Plan Development · Flooding Damages · Roadway Overtopping 11 Alternative Selection Criteria Severity of Existing Problem Public Safety Capital Cost Preserving/Enhancing Existing Property Values Development Potential Social/Economic Impacts Maintenance/Operating Costs 12 City of Dubuque Drainage Basins 13 North Fork Catfish Creek North Fork Catfish Creek Drainage Basin North Fork Catfish Creek Alternatives Evaluated - 100 Year Increase Alt Additional Storage Improve Channel Capacity atImprove Inlet at NW Arterial to No. NW Keyway Rosemont and Penn. Penn.Arterial Keyway 2 ,/ ,/ ,/ ,/ 16 North Fork Catfish Creek Northwest Arterial to Rosemont North Fork Catfish Creek Rosemont to Pe ~a North Fork Catfish Creek Penn n~a to Un~ve North Fork Catfish Alternative Evaluation Alt No. Description 1 Penn Storage NW Arterial Storage /~ Capital Cost (millions) $1.4 Comment Decreases property values at Penn/JFK Changes aesthetics at Penn/JFK $1.6 Minimum land acquisition costs Saves trees and maintains aesthetics at Penn/JFK Preserves property values at Penn/JFK Solves problems close to the source Best hydraulic improvement 3 Penn and NW Arterial Storage $2.4 Additional costs with no appreciable improvement in hydraulics Decreases property values at Penn/JFK Changes aesthetics at Penn/JFK * Recommended Alternative 2o Bee Branch Drainage Basin 2! Bee Branch Drainage Basin West 32nd Street Subarea West 32nd Street Drainage SubArea Alternatives Evaluated - 1 00-Year Multiple One Large West 32nd Street Detention Site Alt No:UpstreamUpstream Detention Detention Site Purchase Sites Upper Carter Blvd Excavate Berm Homes W32-1 at/ v/ v/' W32-2 v/ ~/' V/ W32-3 ~/' ~" V/ W32-4 ~t/ v/' ~/ W32-5 ~/' v/ v/ v/ West 32nd Street Drainage SubArea Detention Site Alternatives West 32nd Street SubArea Alternative Evaluation Alt No. Description W32-1 Multiple storage sites; $5.3 excavate West 32nd cell W32-2 Multiple storage sites; $4.0 berm West 32nd cell W32-3 Upper Carter storage site; $4.7 excavate West 32nd cell W32-4 Upper Carter storage site; $3.5 berm West 32nd cell Capital Cost (millions) Comments Upper Carter storage W32-5' site;excavate and berm $4.7 West 32nd cell * Recommended Alternative Maximum hydraulic benefit Maximum storage at West 32nd cell and Upper Carter Limits flow to capacity of West 32nd cell outlet 2-3 3-4 Remaining Bee Branch Drainage Subareas Remaining Bee Branch Drainage Subareas Detention Site Alternatives Kaufmann Subarea Grandview and Kaufmann Detention Site Alternative Kaufmann Ave~u~ 6rLina~e Subarea /~:u-¥ ~OOI Pote~ial ~o~a~r D~entlon Cell Location ) ~, Bee Branch Findings 16th Street Detention Cell is not a restriction Capacity of Bee Branch sewer is approximately a 7-year return period Inlet capacity to the Bee Branch sewer is adequate to provide full capacity of sewer The principal restriction to flood flows occurs at the railroad tracks Flood volumes from Windsor, Kaufmann, Locust and West 32nd Street converge upstream of the railroad tracks Delaying volume in upstream detention is effective in reducing flooding depths Except for West 32nd Street Subarea, detention areas are not effective Improving West 32nd Street Subarea is effective in reducing flooding above 24th Street;therefore targeted solutions from 24th Street to Mississippi River 32 Bee Branch Drainage Basin Flood Minimization Alternative Improvements Structural Alternatives ~ Open channel floodway ~ Relief storm sewer ~ Create upstream detention ~ Utilize open space upstream detention ~ Flood proofing ~ Pressure sewer system ~ Expand 16th Street Detention capacity ~ Divert West 32nd Street Subarea to the Little Maquoketa ~ Deep storage/pumping tunnel Non-Structural Alternatives Educate/outreach Flood warning System Floodplain buyout Do nothing 33 Bee Branch Drainage Basin Open Channel FloodWay Alternative Open Channel Floodway Features Phase I- 16th Street Cell to 24th Street Only option which reduces 100-year flooding for the lower reach 900 square foot channel; 4,500 feet long; within a 150 foot wide corridor Requires railroad bridge and three road bridges Saves approximately 99% of the homes and businesses in the 100-year flood plain Requires purchase or relocation of approximately 70 homes and businesses Estimated opinion of probable construction cost is $17.1 million 35 Open Channel Floodway Feature Phase II- 16th Street Cell to Garfield 900 square foot channel; 2,500 feet long within a 150 foot wide corridor Requires one railroad bridge and one road bridge Saves approximately 44% of the homes and businesses in the 100-year flood plain Requires purchase or relocation of approximately 13 homes and businesses Estimated opinion of probable construction cost $6.9 million 36 Relief Storm Sewer Features 16th Street Cell to 24th Street Parallel storm sewer to existing Bee Branch storm sewer Only provides protection for a 1 O-year design storm Minimal land acquisition Major utility conflicts Only minimal improvements to flooding depths for 100-year storm Estimated opinion of probable construction cost: One (1) additional conduit - $18.7 million Five (5) additional conduits - $93.5 million 37 Possible Funding Sources General Obligation Bonds Special Assessments Storm Water Utility Federal Congressional Grants Hazard Mitigation Grants'(FEMA) Flood Mitigation Assistance (FEMA) Tax Increment Financing 38