Contents. Critical Analysis Assessing Vulnerability October, Overview/Purpose of Criticality Analysis Criticality Analysis

Transcription

1 Critical Analysis Assessing Vulnerability October, 2016 Murray, Smith & Associates, Inc. Washington APWA Conference Spokane, WA 1 Contents Overview/Purpose of Criticality Analysis Criticality Analysis Facility Pipe Valve Criticality in Design Summary 2 1

2 Water System Resiliency Infrastructure resilience is the ability to reduce the magnitude and/or duration of disruptive events. The effectiveness of a resilient infrastructure or enterprise depends upon its ability to anticipate, absorb, adapt to, and/or rapidly recover from a potentially disruptive event. -Dr. Heather Smith, Global Water Forum, Purpose of Criticality Analysis Consequences of Failure Strength of the system with components off-line Impacts to pressure and supply Distribution network redundancy Valve Criticality and Redundancy Supply and boosting facility firm capacity and connectivity Storage connectivity Prioritization of previously identified projects 4 2

3 Two-part Approach Mass balance Treatment (Source) Pump station Typically assumes largest out of service Storage Hydraulic modeling The largest supply is not always the critical supply Pipe Criticality: Strength of the pipeline network Valve Criticality: Availability and redundancy of valves to isolate breaks, or failed isolation valves Supply and facility criticality 5 Mass Balance Approach Required in Master Planning Treatment redundancy Well supply redundancy Booster station redundancy Availability of storage 6 3

4 Hydraulic Model Approach - Pipelines Pipe Criticality the importance of any single pipe segment in the network Closes each pipe in the system and evaluates the results Finds Functional dead-ends, needed looping Needed tie-ins Service to critical customers 7 Hydraulic Model Approach - Valves Valve Criticality Evaluates consequences if a valve fails to close Isolates each valve in the system and reports number of valves required, demand isolated Indicates valve redundancy Indicates difficulty of isolating a valve in the field and the impact to pressure and supply 8 4

5 Criticality Process Criticality Goals Identify level of desired resiliency Extent of evaluation Single component Entire facility Analysis of dead-ends Context of decision Age of facilities Capital project prioritization Operational flexibility Redundancy Cost 9 Supply and Boosting Criticality Supply Treatment Boosting Well production Automatic on/of capability SCADA Standby Power 10 5

6 Supply Criticality Firm capacity: largest pump out of service Booster station largest pump Largest well pump supply to a zone Typically a spreadsheet analysis Begin with lowest level firm capacity supply Determine if firm boosting capacity is adequate to deliver supply 11 Firm Capacity Analysis 12 6

7 Well Requirements 13 Facilities Criticality Well supply redundancy Booster station redundancy Automatic on/off and backup power Storage Supply and Storage Criticality 14 7

8 Alternate Supply Analysis Timing of reservoir levels at 100%, 75%, 50%, & minimum RESERVOIR 100% FULL (HOUR) 75% FULL (HOUR) 50% FULL (HOUR) MIN FULL (HOUR) AWBREY OUTBACK_ OUTBACK_ OUTBACK_ OVERTURF_EAST OVERTURF_WEST PILOT_BUTTE_ PILOT_BUTTE_ PILOT_BUTTE_ ROCK_BLUFF_ NA 129 TOWER_ROCK COLLEGE_ COLLEGE_ Alternate Supply Analysis TANK DRAWDOWN WITH REDUCED SUPPLY 16 8

9 Alternate Supply Analysis TANK DRAWDOWN WITH REDUCED SUPPLY & EMERGENCY INTERTIE 17 Criticality - Storage Storage is required to provide supply and pressure under high demand and emergency conditions Storage provides for systems in the event of emergencies through the use of standby storage. Requirement often two days of average demand Fire flow and equalization Often delivered to the network through a single pipeline Storage requirements may sometimes be reduced or offset by additional supply Storage supply is linked with redundancy in distribution network (critical pipe analysis) Evaluation of storage to serve system demands must also be hydraulic (Can the needed rate of flow be delivered without excessive head loss through the network) 18 9

10 Hydraulic + Mass Balance - Well and Booster Stations Firm pumping capacity The largest pump out of service MDD for zones served by storage The greater of MDD + Fire or PHD for closed zones Automatic on/off and standby power Spatially critical supply facilities Network weakness connecting two parts of a pressure zone Network weakness connecting storage to demand 19 Closed Zone (no reservoir) 20 10

11 Closed Zone (no reservoir) 21 Closed Zone (no reservoir) 22 11

12 Criticality Process Hydraulic Criteria Develop hydraulic performance criteria Identify the target demand scenario(s) Average day Maximum day Peak hour Fire flow Pressure criteria 20 to 30 psi Extent of pressure drop or disconnection Pressure loss: Service pressure drops below criteria limits Disconnection: The pipeline serves a networked area, and has no parallel. Typically at pressure zone boundaries, or extremities of the system. Number of customers impacted Amount of demand 23 Criticality Process Valve Criteria Number of valves required to isolate a failed valve Valve on distribution main Valve on transmission main Demand isolated by valve closure Impact of critical customer to isolate failed valve 24 12

13 Hydraulic Model Approach - Software OptiCritical- Optimatics EPA Net-based Protector and VCM extension - Innovyze InfoWater extensions, GIS-based WaterCAD/WaterGEMS- Bently Data Intensive Data requirements for hydraulic models Calibrated Model GIS data for the location of system valves GIS data for the location of critical customers Data Streamlining Skeletonizing or phased analysis for practical run-time (roughly 20,000 pipes) 25 Criticality Process Model Development Develop a calibrated hydraulic model Skeletonize the model (as required) Pipe age, material, diameter Create criticality scenarios Target demands based on developed criteria Alternate supply options Identify available facilities Changes to model facilities and controls to enable automated control flexibility Validate the skeletonized model (as required) Distribution of demand Zone isolation maintained Representative elevations retained (elevation of service meters) Intended operations of facilities and controls 26 13

14 Streamline Data 40,000 pipes 8,000 pipes 27 Modeling Criticality Pipe Criticality Define location of critical customers Locate simple dead ends Group results Categorize: disconnection or low pressure Group pipe segments in series with similar hydraulic characteristics Rank the importance of critical pipe groups Validate project criticality with full model 28 14

15 Pipe Criticality Results Supply Cut Off 29 Critical Pipeline Scoring Maximum Pressure Violation- worst case pressure loss Scoring Basis Critical Customer Score (number of critical customers with criteria violation) General Customer Score (customers with criteria violation) Pressure Violation Score (Magnitude of pressure loss) Critical Pressure Loss Pipeline 10 points per critical customer, multiplied by the pressure violation 1 point per 100 equivalent people, multiplied by pressure violation score 1 point per 10 psi pressure violation, round up as long as the pressure violation is 10 psi or greater Disconnection Pipeline N/A 1 point per 100 equivalent people N/A 30 15

16 Ranked Critical Pipes Prioritization of any existing improvement Development of improvements 31 Pipeline Criticality Rank Projects Group ID Max Pressure Violation Pressure Violation Score Critical Customers Equivalent People Customer Score Total Score NH4A , NH , H27B , NH , L T33A NT Rank Critical Customer Score = 10 points per critical customer below criteria pressure multiplied by the pressure violation General Customer Score = 1 point per 100 customers, multiplied by the pressure violation score Pressure Violation Score = 1 point per 10 psi below criteria, round up if over 10 psi Total Score = Critical Customer Score + General Customer Score + Pressure Violation Score 32 16

17 Critical Project Prioritization Secondary ranking criteria Areas with limited capacity Headloss (2ft/1000 ft, 6ft/1000 ft) Velocity 5ft/sec Age/Material older pipeline segment based on age or pipe material Joint types pipeline segments with leadite joints Identified growth areas Hydraulic capacity results may inform the improvement alternative process 33 Criticality Modeling Valve Criticality Skeletonized model (as required) GIS valves Spatially located on model pipes Relocate valves on junctions Associate GIS valves to hydraulic model Run valve criticality Red and yellow valves are required to isolate the black and yellow valve 34 17

18 Valve Criticality - Demand Isolated Valves that would impact critical customers Valves that impact large customer demand Valves that require a large number of other valves to isolate The addition of a few valves may reduce the criticality of many valves 35 Valve Criticality Results Transmission: Red valves require 11 or more valves to isolate Distribution: Yellow valves require 7 or more to isolate 36 18

19 Critical Valve Database Operational value Resource requirements Prioritize valve maintenance program Identifying system improvements Limitations Complexity based on size of system Limited tools for operator reference 37 Criticality in the Design Approach Pipelines Facilities Supply and pump stations Storage tanks Surge or transient analysis 38 19

20 Pipelines New Pipe Construction Considerations: Distribution deficiencies (fire flow, pressure, velocity, headloss, etc.) Looping, redundancy, valve isolation Other utility projects (i.e. road repaving or replacement) Additional Pipe Replacement Program Considerations: Condition Age Material Cost (rehab techniques) Other water system projects How long will modern pipe materials last? 39 Facilities Vulnerability of water wells depends on the type and location of the earthquake, and the well construction and formation in which well is completed Auxiliary power (in place or portable) Standby and/or redundant treatment equipment Seismic implications for water tanks/assessing existing infrastructure Provide valves near the facilities to isolate if the piping system is damaged 40 20

21 Surge or Transient Analysis Transient caused by emergency pump shutdown (power outage) Recommended on new and modified pumping facilities Mitigation Surge chamber OR Reservoir (risk if unavailable) Combination air admission/air relief valves Surge anticipator valve Surge relief valve Check valve 41 Summary Mass balance Pump capacity Available storage Critical pipes Pressure loss Disconnection Prioritization Valve criticality Valves to isolate (manpower) Projects, maintenance priority Criticality in the Design Approach 42 21

22 Acknowledgements A Special Thanks to: City of Spokane Dawn Wirz/Murray, Smith & Associates 43 QUESTIONS? Contact: Joe Foote, PE Murray, Smith & Associates, Inc. M: 421 W Riverside Ave, Suite 762 Spokane, Washington P: E: Joe.Foote@msa-ep.com 44 22