1. Improving Service to Customers by Decommissioning an Elevated Water Storage Tank Jon C. Ford P.E. – Seattle Public Utilities AWWA-PNWS Conference April 30, 2008

2. Overview Seattle Water System Description Seattle Water System Description Maple Leaf 530 Pressure Zone Maple Leaf 530 Pressure Zone Improvements Analysis Improvements Analysis Recommended Improvement Recommended Improvement

3. Seattle Regional Water System

4. Seattle Public Utilities Water System 1.3 million direct service and wholesale customers in King and Snohomish County 1.3 million direct service and wholesale customers in King and Snohomish County 188,000 retail/100 wholesale service connections 188,000 retail/100 wholesale service connections Two surface water sources, one (emergency) groundwater source Two surface water sources, one (emergency) groundwater source 1,600 mi. distribution/159 mi. transmission mains 1,600 mi. distribution/159 mi. transmission mains 15 reservoirs, 7 elevated tanks, 11 standpipes 15 reservoirs, 7 elevated tanks, 11 standpipes

5. Low Pressures in Seattle’s Water System Approximately 45 services have Peak Hourly Demand (PHD) pressure less than 20 psi (<0.1%) Approximately 45 services have Peak Hourly Demand (PHD) pressure less than 20 psi (<0.1%) Approximately 1,500 services have PHD pressure between 20 and 30 psi (0.8%) Approximately 1,500 services have PHD pressure between 20 and 30 psi (0.8%)

6. Locations of Low Pressures

7. Maple Leaf 530 PZ PHD Pressure

8. Base Case PHD Pressure – Low Pressure Area

9. Low Pressures Due to Maple Leaf Tank Elevation

10. Maple Leaf 530 PZ MDD Fire Flow

11. Base Case MDD Fire Flow – Low Pressure Area

12. Project Objectives Increase low pressures to at least 20 psi Increase low pressures to at least 20 psi Determine most cost-effective option of raising pressures above 20 psi Determine most cost-effective option of raising pressures above 20 psi Determine future of Maple Leaf Tank as water storage facility Determine future of Maple Leaf Tank as water storage facility

13. Improvement Alternatives Alternative 1 – Upgrade existing tank Alternative 1 – Upgrade existing tank Alternative 2 – New higher tank Alternative 2 – New higher tank Alternative 3 – Decommission tank Alternative 3 – Decommission tank Alternative 4 – Decommission tank plus booster pump station Alternative 4 – Decommission tank plus booster pump station

14. Comparison of Alternatives

15. Alternative Alternative 1 Upgrade Tank Alternative 2 Higher Tank Alternative 3 Decomm. Tank Alternative 4 Booster PS Minimum Head (ft) 525548545580/545 Required Improvements Seismic Upgrade Seismic Upgrade Recirculation Improvements Recirculation Improvements Soil Remediation Soil Remediation Demolish Old Tank Demolish Old Tank New Tank New Tank Soil Remediation Soil Remediation Pump Station Modifications Pump Station Modifications Booster Pump Station Booster Pump Station Watermain Improvements (for zone separation) Watermain Improvements (for zone separation)

16. Alternatives – PHD Pressure Results PHD Pressure Range (psi) Number of Parcels Base Case Exist Tank Min Level 515 ft Alt 1 Upgrade Tank Min Level 525 ft Alt 2 New Tank Min Level 550 ft Alt 3 No Tank Min Head 540 ft Alt 4 Booster PS No Tank Min Head 580 ft 0-20280000 20-304342100280 30-403935021693711 40-803,3933,0442,3612,7343,149 80-1202,0562,5483,7703,1703,153 Above 12011522 Total6,305

17. Alternatives – MDD Fire Flow Results MDD Fire Flow Range (gpm) Number of Non-Vacant Parcels Base Case Exist Tank Min Level 515 ft Alt 1 Upgrade Tank Min Level 525 ft Alt 2 New Tank Min Level 550 ft Alt 3 No Tank Min Head 540 ft Alt 4 Booster PS No Tank Min Head 580 ft 0-5001673417 500- 1,000 813598394445385 1,000- 2,000 2,5382,6972,3532,4742,799 2,000- 4,000 2,5002,6663,1312,9452,765 > 4,000285308408422337 Total6,303

18. Alternatives Comparison Net Present Value Net Present Value Benefits Benefits Increased Pressure Increased Pressure Increased Fire Flow Increased Fire Flow Decreased Risk Decreased Risk Costs Costs Capital Costs Capital Costs O&M Costs O&M Costs

19. Storage Analysis Storage Component Description Needed in Maple Leaf 530 Pressure Zone? Operational Maintains supply when pumps are shut off No (gravity feed) Equalizing Needed when sources cannot meet demand No (availability > demand) Fire Suppression Provides specific duration of fire flow No (available in Lake Forest Park Reservoir) Standby Provides emergency supply when sources unavailable Only during severe emergencies

20. Benefits Components Increased Pressure Increased Fire Flow Decreased Risk Value from customers’ time savings (hygiene and appliance use) Value from customers’ time savings (hygiene and appliance use) Calculated for pressure increases raising pressure up to 40 psi Calculated for pressure increases raising pressure up to 40 psi Value from reduced risk costs (death, injury, property damage) Value from reduced risk costs (death, injury, property damage) Calculated for fire flow increases up to planning-level flow requirement Calculated for fire flow increases up to planning-level flow requirement Value from reduced risk costs (outages) Value from reduced risk costs (outages)

21. Supply Sources to Maple Leaf 530 Pressure Zone

22. Benefits Comparison (5% Discount Rate, 100-yr return) Benefit Alternative 1 Upgrade Tank Alternative 2 Higher Tank Alternative 3 Decomm. Tank Alternative 4 Booster PS Increased Pressure $1,722,400$4,188,100$3,603,700$4,378,700 Increased Fire Flow $344,700$1,037,500$860,500$977,100 Storage $100,000 $0 Total Benefits $2,167,100$5,325,600$4,464,200$5,355,800

23. Benefits of Increased Pressure Value ($/ERU/Yr) is area under curve $151/ERU/Yr

24. Benefits of Increased Pressure (5% Discount Rate, 100-yr return) Alt 1 Alt 3 Alt 2 Alt 4

25. Planning-Level Fire Flow Requirements (Available Flow at 20 psi Residual Pressure) Single Family: 1,000 gpm Single Family: 1,000 gpm Multi-Family: 2,000 gpm Multi-Family: 2,000 gpm Schools: 2,250 gpm Schools: 2,250 gpm Commercial: 4,000 gpm Commercial: 4,000 gpm Downtown/Industrial/Major Institutions: 8,000 gpm Downtown/Industrial/Major Institutions: 8,000 gpm

26. Reduced risk of deaths and injuries and property damage Reduced risk of deaths and injuries and property damage Fire Flow Benefits Calculation

27. Benefits of Increased Fire Flow (5% Discount Rate, 100-yr return) Alt 1 Alt 3 Alt 2 Alt 4 Alt 1 Alt 3 Alt 4 Alt 2

28. Storage Analysis Storage Component Description Needed in Maple Leaf 530 Pressure Zone? Operational Maintains supply when pumps are shut off No (gravity feed) Equalizing Needed when sources cannot meet demand No (availability > demand) Fire Suppression Provides specific duration of fire flow No (available in Lake Forest Park Reservoir) Standby Provides emergency supply when sources unavailable Only during severe emergencies

29. Maple Leaf 530 Pressure Zone Storage Analysis Operational & Equalizing Storage – not needed Operational & Equalizing Storage – not needed Fire Suppression Storage – provided in Lake Forest Park Reservoir Fire Suppression Storage – provided in Lake Forest Park Reservoir Standby Storage – need reduced by source availability: Standby Storage – need reduced by source availability: Roosevelt Way RCBV – 6,000 gpm Roosevelt Way RCBV – 6,000 gpm Roosevelt Way PS – 3,000 gpm Roosevelt Way PS – 3,000 gpm View Ridge High Service Pump – 2,000 gpm View Ridge High Service Pump – 2,000 gpm Roosevelt Turbine – 800 gpm Roosevelt Turbine – 800 gpm

30. Standby Storage Benefit Calculation Value = Risk Cost = Probability of Service Outage x Consequences of Service Outage Value = Risk Cost = Probability of Service Outage x Consequences of Service Outage Probability: 0.02/yr (outage event exceeding MDD) Probability: 0.02/yr (outage event exceeding MDD) Consequence: $280,000 per episode Consequence: $280,000 per episode Value = 0.02/yr x $280,000 = $5600/yr Value = 0.02/yr x $280,000 = $5600/yr PV = $100,000 PV = $100,000

31. Storage and Supply Availability to Maple Leaf 530 Pressure Zone Lake Forest Park Reservoir provides storage Lake Forest Park Reservoir provides storage Gravity feed through Roosevelt Way RCBV/PRV Gravity feed through Roosevelt Way RCBV/PRV Capacity > PHD Capacity > PHD Storage volume (60 MG) Storage volume (60 MG) Backup sources available Backup sources available Roosevelt Way Pump Station Roosevelt Way Pump Station View Ridge High Service Pump View Ridge High Service Pump Roosevelt Turbine Roosevelt Turbine

32. Costs Comparison (5% Discount Rate, 100-yr return) Alternative 1 Upgrade Tank Alternative 2 Higher Tank Alternative 3 Decomm. Tank Alternative 4 Booster PS Tank Capital Costs $4,550,000$6,650,000$0$0 Pump Station Capital Costs $0$50,000$105,000$1,100,000 Watermain and Valve Capital Costs $0$0$0$1,119,300 O&M Costs (PV) $200,000$400,000$0$200,000 Total Costs $4,750,000$7,100,000$105,000$2,419,300 Costs with Demolition $4,750,000$7,100,000$1,105,000$3,419,300

33. NPV Comparison Alternative 1 Alternative 1 NPV = -$2,582,900 NPV = -$2,582,900 Alternative 2 Alternative 2 NPV = -$1,774,400 NPV = -$1,774,400 Alternative 3 Alternative 3 NPV = $4,359,200 NPV = $4,359,200 Alternative 4 Alternative 4 NPV = $2,936,500 NPV = $2,936,500 B/C ratio = 0.46 B/C ratio = 0.75 B/C ratio = 42.5 B/C ratio = 2.21

34. NPV Comparison

35. Tank Decommission vs. Demolition No longer needed as water system facility No longer needed as water system facility Value as antenna tower Value as antenna tower Costs of demolition and soil remediation Costs of demolition and soil remediation Possible landmarks issue Possible landmarks issue Communication to customers Communication to customers

36. Recommendation Recommend Alternative 3: Decommission Maple Leaf Tank and serve the Maple Leaf 530 Pressure Zone directly from the 550 Pipeline Recommend Alternative 3: Decommission Maple Leaf Tank and serve the Maple Leaf 530 Pressure Zone directly from the 550 Pipeline

37. Conclusions Decommissioning the Maple Leaf Tank increases pressures and fire flow Decommissioning the Maple Leaf Tank increases pressures and fire flow Supply redundancy provides for minimal outage risk Supply redundancy provides for minimal outage risk Decommissioning still preferred alternative if demolition costs are included Decommissioning still preferred alternative if demolition costs are included

38. Alt 3 PHD Pressure – Low Pressure Area

39. Alt 3 MDD Fire Flow – Low Pressure Area

40. Questions?

41. Benefits Benefits from Increased Pressure Benefits from Increased Pressure Benefits from Increased Fire Flow Benefits from Increased Fire Flow Benefits from Maple Leaf Tank Standby Storage Benefits from Maple Leaf Tank Standby Storage

42. Benefits from Increased Pressure Based on Queen Anne PS Analysis Based on Queen Anne PS Analysis Value determined for 1 psi increase Value determined for 1 psi increase Value decreases as pressure increases Value decreases as pressure increases No value for increases beyond 40 psi No value for increases beyond 40 psi

43. Benefits from Increased Fire Flow Based on Planning-Level Requirements Based on Planning-Level Requirements Reduction in risk costs: Reduction in risk costs: Death Death Injury Injury Property Damage Property Damage Risks decrease with increased fire flow (up to requirements) Risks decrease with increased fire flow (up to requirements)

44. Storage Benefits Standby Storage only Standby Storage only Maple Leaf Reservoir nearby (unlike Queen Anne) Maple Leaf Reservoir nearby (unlike Queen Anne)

45. Costs Comparison CostAlternative 1Alternative 2Alternative 3Alternative 4 Tank Upgrade$3,300,000-- Tank Demolition--$1,000,000-- Tank Replacement--$4,400,000-- Tank Recirculation Improvements $200,000 -- Future Tank Recoating (PV)$700,000 -- Soil Remediation$350,000 -- Subtotal Tank Costs$4,550,000$6,650,000$0 Booster Pump Station$1,000,000 Pump Station Valve Modifications --$50,000$100,000 SCADA Reprogramming-- $5,000-- Subtotal Pump Stations$0$50,000$105,000$1,100,000 New Watermains-- $489,300 New Valves-- $630,000 Subtotal Watermains$0 $1,119,300 Total Capital Costs$4,550,000$6,700,000$105,000$2,219,300

46. NPV Sensitivity to Discount Rate

47. NPV Sensitivity to Pressure Benefit

48. Decommissioning - How Do We Make It Happen? Cheryl Capron, Senior Water System Operator Seattle Public Utilities PNWS-AWWA Conference April 30, 2008

49. Overview Operations input to asset management process Operations input to asset management process Compensating improvements Compensating improvements New procedures New procedures Operational testing Operational testing Retirement Retirement

50. Operations Input to Asset Management Process How the tank and zone are actually operated How the tank and zone are actually operated Reliability and condition of existing components Reliability and condition of existing components Identify all functions of tank Identify all functions of tank Venting & surge protection Venting & surge protection Holds positive pressure in zone if pumps fail Holds positive pressure in zone if pumps fail Smooths diurnal demand on source Smooths diurnal demand on source Provides opportunity to boost Cl2 residual Provides opportunity to boost Cl2 residual

51. Compensating Improvements Pressure relief? Pressure relief? Booster chlorine capability replaced? Booster chlorine capability replaced? More instrumentation? More instrumentation? Upgrade, add, replace pumps? Upgrade, add, replace pumps? Variable output to match demand Variable output to match demand Hot standby power Hot standby power Upgrade, add, replace flow control valves? Upgrade, add, replace flow control valves? Adjust valve speed Adjust valve speed

52. New Procedures Revise minimum and maximum zone operating pressures Revise minimum and maximum zone operating pressures Hydraulic modeling Hydraulic modeling Response to high and low pressure alarms Response to high and low pressure alarms When do we shut down gravity supply and switch to pumps? When do we shut down gravity supply and switch to pumps? Revise SCADA graphics & programming Revise SCADA graphics & programming Train the operators Train the operators

53. 3-Part Operational Testing PRV Loop PRV Loop Close pump discharge line and start pump Close pump discharge line and start pump Pressure Zone Test Scenarios (Tank off-line) Pressure Zone Test Scenarios (Tank off-line) Most likely to go wrong? Most likely to go wrong? SCADA glitch - valve opens too far SCADA glitch - valve opens too far Power fail – pump stops Power fail – pump stops Peak Season Test Peak Season Test Are we absolutely sure we won’t need this tank anymore? Are we absolutely sure we won’t need this tank anymore?

54. Operational Test Objectives Verify new 6” PRV loop will function as needed Verify new 6” PRV loop will function as needed Verify an existing off-site 4” PRV functions as needed Verify an existing off-site 4” PRV functions as needed Document location & effect of discharge flow to environment. Document location & effect of discharge flow to environment. Revise settings so that new 6” PRV opens first. Revise settings so that new 6” PRV opens first. Verify high & low psi alarm settings are ok Verify high & low psi alarm settings are ok

55. Test Plan Objectives Objectives Prior to Test Prior to Test Customers ready for pressure change Customers ready for pressure change Customer service reps aware of pressure changes & dirty water from testing Customer service reps aware of pressure changes & dirty water from testing Fire department aware pressure surges may trigger false alarms Fire department aware pressure surges may trigger false alarms SCADA & new operating procedure ready SCADA & new operating procedure ready All compensating improvements completed All compensating improvements completed

56. Test Plan Preset the system Preset the system Reservoir levels Reservoir levels Valves positioned Valves positioned Field staffing Field staffing At PRVs to observe & document At PRVs to observe & document At tank inlet to put back on line quickly At tank inlet to put back on line quickly

57. Test Plan Step by step procedure Step by step procedure Establish supply to zone Establish supply to zone Tank inlet closed Tank inlet closed Slowly boost supply to force PRVs open Slowly boost supply to force PRVs open Verify they’re working Verify they’re working Slowly back off supply to close PRVs Slowly back off supply to close PRVs Adjust pressure settings and alarm settings Adjust pressure settings and alarm settings

58. Retirement Disconnect Disconnect Inlet/Outlet Inlet/Outlet Where? Where? Abandon in place or remove? Abandon in place or remove? Overflow? Overflow? Drain? Drain?

59. Retirement Decommission components Decommission components Cathodic protection Cathodic protection Electrical Electrical SCADA SCADA Sampling system Sampling system Demolish or mothball? Demolish or mothball? Mothballing requires regular inspections Mothballing requires regular inspections

60. Questions?

61. Benefits of Increased Fire Flow Annual Benefit Alternative 1 Upgrade Tank Alternative 2 Higher Tank Alternative 3 Decomm. Tank Alternative 4 Booster PS Avoided Death & Injury Risk $10,650$34,649$28,735$33,370 Avoided Property Damage Risk $6,717$17,624$14,621$15,859 Total Annual Benefits $17,367$52,273$43,356$49,229