Ohio AWWA SW District MeetingWater Distribution System Planning Friday, Oct. 14, 2011 Dan Barr, PE and Mark Upite, PE Burgess & Niple, Inc.
Introduction• Do I have any problems in my system?• How do I know what’s not working?• How complete is my mapping?• Are main breaks a problem?• What is adequate storage?• How do I know what to replace first? You need a plan!
Information Required for Planning• Piping Network - GIS, CAD, Hard Copy• Customer Demands - GIS, Evenly distributed, Billing Records with Address Locater in Esri’s ArcMap (Geocoding)• Ground Elevations - GIS, LIDAR, USGS 7.5 Min Map• Pump, Control Valve, and Tank Information - Pump Curves, Valve Type/Status, Tank Geometry/Elevations
Additional Information for Planning• Population Forecasts• Hydrant Data• Isolation Valve Data• Customer Meter Locations
Model BenefitsThe best plans start with a water distribution systemmodel. • A model is a computer simulation of the system. • Predicts pressure and flows under varying conditions. • Can determine what the existing and future needs are to optimize system performance.
Model Creation and Data EntryInsert Pipes, Contours/Surface, Background MappingClean Up Junctions, Verify Cross Connections, Assign Elevations
Geospatially Locating Demands- Incorporate GIS Meter Locations or Utilize Geocoding to Develop Locations- Use Billing Records to Apply ADD to Meter Location- Allocate Meter Location and Values to Nearest Junction- Evenly Distribute Unaccounted For Losses
Global Edit Demands- Now a ADD Scenario is Setup, Create Scenarios for MDD and PHD- Typical MDD is 1.5 X ADD- Typical PHD = 2 X MDD- Use Historic WTP Production or Master Meter Records if Available- Modify Pumps/Booster Pumps/Tank Levels/etc.
Calibration & Fire Flow Tests Field Data is Needed to Calibrate the Model.
Model Update – Darwin Calibrator- Field Data is Compared Against Model Output- Algorithms are Run Millions of Times and Pipe Friction is Adjusted for EachPipe Until Field Data and Model Output Converge.
Model Update – CalibrationThe City should be able to trust the model with million dollar waterline decisions!Decisions made with the model can save a City millions!
Fire Flow Capacities and Durations will be Dependent Upon:Insurance Insurance Service Office (ISO), Factory Mutual Insurance Company (FM Global)Local Code Building and ZoningLocal Authority (Has power to supersede both above) Fire Chief/Fire Marshall
Example of Residential Fire Flow Trouble Spot and Evaluation of Cost Effective Solution : Exist fire flows meet insurance and local code. However, the Fire Marshall wants all hydrants in a particular residential area to have a minimum of 1,000 gpm at max day demand while maintaining 20 psi residual pressure.
Storage AnalysisA comprehensive, innovative, and straightforwardstorage and pumping analysis that will helpdetermine: Distribution system capabilities during critical conditions Current and future storage/pumping requirements Determine and test proposed solutions District by district requirements Combines many storage concepts into one analysis. Incorporates minimum turnover requirements No mysterious factors or multipliers
Storage Evaluation Spreadsheet Distribution System Storage Requirements Sample Your Your Your Your Your Criteria (unit) District District 1 District 2 District 3 District 4 District 5Average daily demands (gpm) 100Peak day demands (gpm) 200Peak hour demands (gpm) 300Booster pump firm capacity (gpm) 200Design fire flow (gpm) 3,500Design fire duration (hours) 3Design fire flow supplied by storage (gpm) 3,500 0 0 0 0 0Total fire flow storage capacity required (gal) 630,000 0 0 0 0 0Balancing storage required (gal) 48,000 0 0 0 0 0Desired emergency outage duration (hours) 6Emergency outage required capacity assuming average daily demands (gal) 36,000 0 0 0 0 0 Subtotal 630,000 0 0 0 0 0 Required storage capacity (gal)Desired turnover percentage 20% 20% 20% 20% 20% 20%Required storage volume for desired turnover (gal) 126,000 0 0 0 0 0Total additional capacity required for turnover (gal) 78,000 0 0 0 0 0 Total 708,000 0 0 0 0 0 Required storage capacityCurrent storage capacity (gal) 1,000,000Difference (gal) 292,000 0 0 0 0 0Deficiencies will display in redMaximum sustainable storage capacity (gal) 720,000 0 0 0 0 0
Analysis ComponentsThis analysis determines theminimum required storagevolume for each of thefollowing components: Operational (balancing and turnover) The Fire Protection Three Components Outages of Storage
Analysis Data Requirements Water demands by district is ideal Existing system storage volumes Existing pumping capacity
Emergency OutagesThis component deals with situations when thesource(s) for each district is out of service. Assumptions for determining minimum outage volume: – The minimum number of hours the system must operate on storage alone – The demands during the outage The system’s emergency management plan must coordinate with these assumptions
Emergency Outage EquationsMinimum Storage Volume Demand (gpm) x Outage Requirement (hours) x 60 (minutes/hour) = Required Volume (gal)In Millions of Gallons Per Day Demand (mgd) x 1,000,000 gal/mil gal x Outage Requirement (hours) / 24 (days/hours) = Required Volume (gal)
Fire ProtectionThis component is sized by determining the design fire ineach district. The design fire is an assumption based on a number of factors – Local fire department requirements – Organizations like ISO, Inc. that publish public fire protection data – Ohio Fire Code Begin analysis after choosing design fire – How much of required fire flow rate can be delivered by system pumping – What portion of the design fire will need to be delivered by system storage
Fire Protection EquationsCapacity Available for Fire Protection Firm Pumping Capacity (gpm) – Maximum Day Demands (gpm) = Pumping Capacity available for fire protection (gpm)Required System Storage [Design Fire Flow Rate (gpm) – Available Pumping Capacity (gpm)] x [Design Fire Duration (hours)] x (60 minutes/hour) = Required System Storage (gal)
Operational StorageThis component includes storage volume utilizedfor: Daily turnover of the tank – Tank turnover is used to keep stored water fresh Current industry practice and the Ohio EPA’s recommendation: - Turnover 20% to 40% of the tank every day Maximum hour balancing – Storage required to supply demands over the system’s pumping capacity
Operational EquationsTurnoverStorage Volume (gal) x Turnover Target Percentage (%) = Required System Storage (gal)BalancingMaximum Hour Demand (gpm) – System Pumping Capacity (gpm)] x 8 hours x 60 (minutes/hour) = Required System Storage (gal)
Total Required Storage Volume Per DistrictAfter calculating the three component volumes(emergency outage, fire protection and operationalstorage) determine the total required volume by: Adding all three components Adding operational component to the larger of the two volumes for outage and fire protection Sizing the required tankage on the largest of the three componentsFinal parameter: Determine if the district has enough average daily demand to turn over the required storage
Maximum Sustainable Storage• (5)x(average daily demand) = Maximum Sustainable Storage for 20% turnover.• (4)x(average daily demand) = Maximum Sustainable Storage for 25% turnover.
Final StepsDetermine remedies for deficiencies discoveredduring the process. Problems can be solved by a combination of: – Increased pumping capacity May solve fire flow problem economically Power or mechanical failures could occur Increased storage volume – Increases emergency outage capacity without fear of mechanical or power-related failures – Expensive, might have siting issues Reduced demands – Usually not possible unless customers can be shifted to another neighboring pressure district
Common Situations Too much storage Too little storage Storage in the wrong place
Asset ManagementManage assets based on weighted parameters:• Age• Material• Criticality• Capacity• Service History• Pavement Plan
Conclusion and Summary• Planning is key for current and future system infrastructure. • Data is required. • Model will prioritize capital improvements. • Proper sizing of storage is vital for proper operation and avoiding further issues. • Asset Management is key to maximize infrastructure life-cycle.