Beyond an Average Day - How Much Water Should You Store?


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Beyond an Average Day - How Much Water Should You Store?

  1. 1. Beyond an “Average Day” How Much Water Should Be Stored Dan Barr, PE Burgess & Niple, Inc.
  2. 2. Introduction <ul><li>A comprehensive, innovative, and straightforward storage and pumping analysis that will help determine: </li></ul><ul><ul><li>Distribution system capabilities during critical conditions </li></ul></ul><ul><ul><li>Current and future storage/pumping requirements </li></ul></ul><ul><ul><li>Determine and test proposed solutions </li></ul></ul><ul><ul><li>District by district requirements </li></ul></ul><ul><ul><li>Combines many storage concepts into one analysis. </li></ul></ul><ul><ul><li>Incorporates minimum turnover requirements </li></ul></ul><ul><ul><li>No mysterious factors or multipliers </li></ul></ul>
  3. 3. Analysis Components <ul><li>This analysis determines the minimum required storage volume for each of the following components: </li></ul><ul><ul><li>Operational (balancing and turnover) </li></ul></ul><ul><ul><li>Fire Protection </li></ul></ul><ul><ul><li>Outages </li></ul></ul>The Three Components of Storage
  4. 4. Analysis Data Requirements <ul><ul><li>Water demands by district is ideal </li></ul></ul><ul><ul><li>Existing system storage volumes </li></ul></ul><ul><ul><li>Existing pumping capacity </li></ul></ul>
  5. 5. Emergency Outages <ul><li>This component deals with situations when the source(s) for each district is out of service. </li></ul><ul><ul><li>Assumptions for determining minimum outage volume: </li></ul></ul><ul><ul><ul><li>The minimum number of hours the system must operate on storage alone </li></ul></ul></ul><ul><ul><ul><li>The demands during the outage </li></ul></ul></ul><ul><ul><li>The system’s emergency management plan must coordinate with these assumptions </li></ul></ul>
  6. 6. Emergency Outage Equations <ul><li>Minimum Storage Volume </li></ul><ul><ul><li>Demand (gpm) x Outage Requirement (hours) x 60 (minutes/hour) = Required Volume (gal) </li></ul></ul><ul><li>In Millions of Gallons Per Day </li></ul><ul><ul><li>Demand (mgd) x 1,000,000 gal/mil gal x Outage Requirement (hours) / 24 (days/hours) = Required Volume (gal) </li></ul></ul>
  7. 7. Fire Protection <ul><li>This component is sized by determining the design fire in each district. </li></ul><ul><ul><li>The design fire is an assumption based on a number of factors </li></ul></ul><ul><ul><ul><li>Local fire department requirements </li></ul></ul></ul><ul><ul><ul><li>Organizations like ISO, Inc. that publish public fire protection data </li></ul></ul></ul><ul><ul><ul><li>Ohio Fire Code </li></ul></ul></ul><ul><ul><li>Begin analysis after choosing design fire </li></ul></ul><ul><ul><ul><li>How much of required fire flow rate can be delivered by system pumping </li></ul></ul></ul><ul><ul><ul><li>What portion of the design fire will need to be delivered by system storage </li></ul></ul></ul>
  8. 8. Fire Protection Equations <ul><li>Capacity Available for Fire Protection </li></ul><ul><ul><li>Firm Pumping Capacity (gpm) – Maximum Day Demands (gpm) = Pumping Capacity available for fire protection (gpm) </li></ul></ul><ul><li>Required System Storage </li></ul><ul><ul><li>[Design Fire Flow Rate (gpm) – Available Pumping Capacity (gpm)] x [Design Fire Duration (hours)] x (60 minutes/hour) = Required System Storage (gal) </li></ul></ul>
  9. 9. Operational Storage <ul><li>This component includes storage volume utilized for: </li></ul><ul><ul><li>Daily turnover of the tank </li></ul></ul><ul><ul><ul><li>Tank turnover is used to keep stored water fresh </li></ul></ul></ul><ul><ul><ul><ul><li>Current industry practice and the Ohio EPA’s recommendation: </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Turnover 20% to 40% of the tank every day </li></ul></ul></ul></ul></ul><ul><ul><li>Maximum hour balancing </li></ul></ul><ul><ul><ul><li>Storage required to supply demands over the system’s pumping capacity </li></ul></ul></ul>
  10. 10. Operational Equations <ul><li>Turnover </li></ul><ul><li>Storage Volume (gal) x Turnover Target Percentage (%) = Required System Storage (gal) </li></ul><ul><li>Balancing </li></ul><ul><li>Maximum Hour Demand (gpm) – System Pumping Capacity (gpm)] x 8 hours x 60 (minutes/hour) = Required System Storage (gal) </li></ul>
  11. 11. Total Required Storage Volume Per District <ul><li>After calculating the three component volumes (emergency outage, fire protection and operational storage) determine the total required volume by: </li></ul><ul><ul><li>Adding all three components </li></ul></ul><ul><ul><li>Adding operational component to the larger of the two volumes for outage and fire protection </li></ul></ul><ul><ul><li>Sizing the required tankage on the largest of the three components </li></ul></ul><ul><li>Final parameter: </li></ul><ul><ul><li>Determine if the district has enough average daily demand to turn over the required storage </li></ul></ul>
  12. 12. Maximum Sustainable Storage <ul><li>(5)x(average daily demand) = Maximum Sustainable Storage for 20% turnover. </li></ul><ul><li>(4)x(average daily demand) = Maximum Sustainable Storage for 25% turnover. </li></ul>
  13. 13. Final Steps <ul><li>Determine remedies for deficiencies discovered during the process. </li></ul><ul><ul><li>Problems can be solved by a combination of: </li></ul></ul><ul><ul><ul><li>Increased pumping capacity </li></ul></ul></ul><ul><ul><ul><ul><li>May solve fire flow problem economically </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Power or mechanical failures could occur </li></ul></ul></ul></ul><ul><ul><li>Increased storage volume </li></ul></ul><ul><ul><ul><li>Increases emergency outage capacity without fear of mechanical or power-related failures </li></ul></ul></ul><ul><ul><ul><li>Expensive, might have siting issues </li></ul></ul></ul><ul><ul><li>Reduced demands </li></ul></ul><ul><ul><ul><li>Usually not possible unless customers can be shifted to another neighboring pressure district </li></ul></ul></ul>
  14. 14. Common Situations <ul><ul><li>Too much storage </li></ul></ul><ul><ul><li>Too little storage </li></ul></ul><ul><ul><li>Storage in the wrong place </li></ul></ul>
  15. 15. Questions? <ul><ul><li>Preformatted spreadsheet with calculations available </li></ul></ul><ul><ul><li>Contact: </li></ul></ul><ul><ul><li>Dan Barr, PE </li></ul></ul><ul><ul><li>[email_address] </li></ul></ul>