CONFIRMING WET WEATHER TREATMENT FACILITY HYDRAULIC DESIGN WITH PHYSICAL MODEL STUDY TONY YEE, PE JARED HUTCHINS, PE METROPOLITAN SEWER DISTRICT OF GREATER CINCINNATI BLACK & VEATCH
WET WEATHER TREATMENT FACILITY SITE Ohio WEA AWWA 2014 Technical Conference & Expo l N INTRODUCTION 2
AGENDA PROJECT BACKGROUND MODEL PLAN MODEL RESULTS 3
PROJECT BACKGROUND 4
PROJECT DRIVERS Ohio WEA AWWA 2014 Technical Conference & Expo l PROJECT BACKGROUND Mitigate highly active combined sewer overflow Located at terminus of Combined Sewer 937 Residential area Frequent odor and aesthetic issues during dry and wet weather Consent decree driven project 5
PROJECT LOCATION N Ohio WEA AWWA 2014 Technical Conference & Expo l Upper Muddy Creek Basin Project Location PROJECT BACKGROUND Ohio River Muddy Creek Basin Cincinnati Project background 6
RECEIVING WATERS Ohio WEA AWWA 2014 Technical Conference & Expo l PROJECT BACKGROUND Sewer debris discharges to creek during wet weather 7
Ohio WEA AWWA 2014 Technical Conference & Expo l CSO 522 VOLUME CONTROL FOR TYPICAL YEAR Typical Year Overflow from Existing Outfall 522 66 events, 517 MG, 635 hours of discharge PROJECT BACKGROUND Flow Rates V r 64.7 MG: 4 Overflows Per Typical Year: Typical Year, 15 min Peak: 10 year, 24 hr: Outfall capacity: Ultimate Hydraulic Capacity 106 mgd 185 mgd 434 mgd 988 mgd 1,400 mgd Regulatory Volume Capture Criteria Wide range of flows to manage 8
THE SOLUTION Ingress Drive Ohio WEA AWWA 2014 Technical Conference & Expo l Egress Drive Operations Building Existing CSO Outfall Neighbors Creek PROJECT BACKGROUND N Enhanced High Rate Treatment Site constraints dictated facility arrangement 9
INFLUENT CONTROL STRUCTURE Ohio WEA AWWA 2014 Technical Conference & Expo l Combined Sewer Inlet PROJECT BACKGROUND Dissipate energy Direct flows into facility up to peak treatment capacity, and release excess flows to creek Promote solids clean up post event for odor control No dry weather flow Grit/Dewatering Trench Grit/Stone Pit Tipping Buckets N Storm Weirs to Creek 10
INFLUENT FINE SCREENS Remove CSO debris Protect downstream equipment Ohio WEA AWWA 2014 Technical Conference & Expo l Belt Conveyor PROJECT BACKGROUND N Screenings Dumpster Fine Screens Chain and rake, ½ aperture, 92.5 mgd each 11
INFLUENT PUMP STATION Delivers flow into the EHRT facility Trench wet well design to minimize solids deposition Ohio WEA AWWA 2014 Technical Conference & Expo l PROJECT BACKGROUND Influent PS with submersible non clog pumps in trench style wet well 12
MODEL PLAN 13
SO WHAT IS THE PURPOSE? Ohio WEA AWWA 2014 Technical Conference & Expo l Manage solids and provide uniform flow distribution at diversion structure MODEL PLAN Avoid certain phenomena at Pump Station Submerged vortices Free surface vortices Preswirl magnitude and fluctuation with time Nonuniform distribution of velocity in space and time at the impeller eye Entrained air or gas bubbles Can have adverse affect on pump performance and can lead to maintenance issues HIS 9.8 2012 14
HYDRAULIC INSTITUTE STANDARD 9.8 2012 Ohio WEA AWWA 2014 Technical Conference & Expo l Prove design deviating from standard Pump station exceeds threshold capacity of standard Individual pump exceeds threshold capacity of standard Screens creating high velocity jets near pump intakes MODEL PLAN Significant cross flow velocities compared with pump bay Properly apply standard for good hydraulic performance, or prove a custom design HIS 9.8 2012 15
MODEL DOMAINS Ohio WEA AWWA 2014 Technical Conference & Expo l Influent PS Physical Model Influent Control Structure CFD Influent Control Structure Physical Model N MODEL PLAN CFD to cover high flows not feasible with physical model 16
MODEL ACCEPTANCE CRITERIA Ohio WEA AWWA 2014 Technical Conference & Expo l Influent Control Structure Even flow distribution Sediment collection prior to screens MODEL PLAN Influent Pump Station Wet Well Free surface vortices Subsurface vortices Swirl angles Velocity distribution No industry standard on physical model acceptance criteria for diversion structures 17
MODEL TEST SCENARIOS Ohio WEA AWWA 2014 Technical Conference & Expo l Test Condition Prototype Conditions Event Q (mgd) CFD Testing ICS Physical Model IPS Physical Model 1 25% of annual flows 30 X X 2 Firm treatment capacity 106 X X X 3 Ultimate treatment capacity 185 X X X 4 Typical yr 24 hr 421 X X 5 2 yr 24 hr 643 X X MODEL PLAN 6 5 yr 24 hr 873 X X 7 10 yr 24 hr 1,053 X 8 25 yr 24 hr 1,321 X 9 100 yr 24 hr 1,482 X 18
Ohio WEA AWWA 2014 Technical Conference & Expo l INFLUENT CONTROL STRUCTURE MODEL DEVELOPMENT MODEL PLAN Fabrication drawing checks 19
Ohio WEA AWWA 2014 Technical Conference & Expo l MODEL PLAN INFLUENT CONTROL STRUCTURE MODEL OVERVIEW 20
MODEL RESULTS 21
CFD RESULTS VELOCITY Ohio WEA AWWA 2014 Technical Conference & Expo l 185 mgd 1,482 mgd Baseline N Mod 1 Mod 2 Eddy formation and turbulent, non uniform flow 22
Ohio WEA AWWA 2014 Technical Conference & Expo l PRELIMINARY DESIGN ENHANCEMENTS N Mod 2: Flow Guiding Baffle Mod 1: Flow Turning Vanes MODEL RESULTS Two modifications proposed at ICS 23
Ohio WEA AWWA 2014 Technical Conference & Expo l PRELIMINARY DESIGN ENHANCEMENTS MODEL RESULTS Mod 1: Flow Turning Vanes Modification 1 to improve flow distribution at 90 degree bend 24
Ohio WEA AWWA 2014 Technical Conference & Expo l PRELIMINARY DESIGN ENHANCEMENTS Mod 2: Flow Guiding Baffle MODEL RESULTS Modification 2 to block flow to Screens 1 & 2 25
CFD & PHYSICAL MODEL RESULTS Ohio WEA AWWA 2014 Technical Conference & Expo l Screen 1 Screen 2 Screen 3 Screen 1 Screen 2 Screen 3 MODEL RESULTS CFD results validated with physical model 26
Ohio WEA AWWA 2014 Technical Conference & Expo l CFD & PHYSICAL MODEL RESULTS SCREEN FLOW Prototype Conditions with Mod 1 Flow Split Through Screens Test Condition Event Q (mgd) Screen 1 Screen 2 Screen 3 1 25% of annual flows 30 2 Firm treatment capacity 106 44% > 35% 31% > 32% 25% > 33% 3 Ultimate treatment capacity 185 49% > 40% 32% > 31% 19% > 29% 4 Typical yr 24 hr 421 55% > 31% > 14% > MODEL RESULTS 5 2 yr 24 hr 643 69% > 41% 36% > 29% 4% > 29% 6 5 yr 24 hr 873 76% > 42% > 19% > 7 10 yr 24 hr 1,053 80% > 32% > 12% > 8 25 yr 24 hr 1,321 82% > 32% > 13% > 9 100 yr 24 hr 1,482 77% > 47% 33% > 30% 10% > 23% All screen flows meet specification 27
Ohio WEA AWWA 2014 Technical Conference & Expo l BASELINE PHYSICAL MODEL RESULTS GRIT Q Q Q MODEL RESULTS 30 mgd 106 mgd 185 mgd Challenge area identified at 90 degree bend 28
Ohio WEA AWWA 2014 Technical Conference & Expo l MODIFIED PHYSICAL MODEL RESULTS GRIT N Q Q Q Q Q Q MODEL RESULTS Baseline 185 mgd Mod 2 185 mgd Mods 1 & 2 185 mgd Mod 3 185 mgd Challenge area identified at 90 degree bend 29
MODEL FINDINGS STONE PIT Ohio WEA AWWA 2014 Technical Conference & Expo l Large gravel to small cobbles passed the stone pit Consider replacing standard pit with modified trench for improved performance Consider armoring columns MODEL RESULTS Q 30
Ohio WEA AWWA 2014 Technical Conference & Expo l FURTHER PHYSICAL MODEL RECOMMENDATIONS Q Q Q N Q N MODEL RESULTS Stone Chamber Smoothed 90 deg Bend Screen Channel Slope Further enhancements possible for solids management & flow equalization 31
Tony Yee Project Manager 513 244 5180 anthony.yee@cincinnati oh.gov Jared Hutchins Project Engineer 513 936 5137 hutchinsjc@bv.com www.bv.com