Southwest Section AWWA 2018 – Baton Rouge, LA How to Make the Most of Your CIP: Using a Risk Based Approach for Prioritizing Water Treatment Plant Renewal Chad M. Simmons, P.E., BCEE – Freese and Nichols Brett Buff, P.E. – North Texas Municipal Water District Southwest Section AWWA 2018 – Baton Rouge, LA

location Wylie WTP 2

NTMWD Service area NTMWD serves >1.6M people across 90 communities with 6 WTPs Wylie WTP single site with 4 WTPs Plant 1 constructed in 1950’s and Plant 4 in early 2000’s 3

Wylie water treatment system Raw Water 3 Plant 3 Current capacity = 770 MGD Future capacity = 840 MGD Plant 4 Plant 1 -1950’s (70 MGD); rapid mix, clariflocculators, filters, chem feed, ozone Plant 2 – 1980’s (280 MGD), 8 trains, rapid mix, flocculation/sed basins, filters Plant 3 – 1990’s, (280 MGD), 8 trains, rapid mix, flocculation/sed basins, filters Plant 4 – early 2000’s, (140 MGD), 4 trains, rapid mix, flocculation/sed basins, filters Chem Feed: ammonia, caustic, chlorine, chlorine dioxide, ferric sulfate, fluoride, lime, ozone, polymer Plant 2 Plant 1 4

Use a Risk Based Approach to: Determine what to fix and when Purpose Use a Risk Based Approach to: Determine what to fix and when Develop a prioritized list of capital projects Integrate improvements in the existing CIP Preserve required capacity

Refine Asset Management approach drivers Aging infrastructure Refine Asset Management approach Desire to incorporate system renewal into CIP Business approach using Risk Management in infrastructure renewal

Methodology Asset inventory Develop scoring system Perform site visits at Plants I, II, III, IV Apply condition and criticality score Prioritize improvements Prepare cost estimates Combine improvements into prioritized projects Incorporate into CIP

Facilities evaluated Plants I-IV, Raw Water Pump Stations and piping from Lake Lavon to High Service Pump Stations Raw Water Pump Station and Conveyance Piping Rapid Mix, Flocculation, Sedimentation, Filters Disinfection Facilities, Clear Wells High Service Pump Stations Yard Piping (>24” and select smaller process lines) Chemical Feed and Storage Backwash Reclamation Sludge Handling Electrical and Instrumentation Flow Meters

Risk = ƒ (Condition x Criticality) Risk based assessment Risk = ƒ (Condition x Criticality) What is the Likelihood of Asset Failure? What is the Consequence of Asset Failure? Asset age Asset material Performance of asset Maintenance history Water quality/System impact Capacity affected Redundancy Outage duration

Condition Scoring (Vertical Assets) DESCRIPTION New, perfect condition 25 Good condition, no improvements recommended to maintain function 50 Fair condition, improvements recommended to improve performance or efficiency 75 Poor condition, improvements recommended to maintain reliability 100 Imminent failure, rehabilitation or replacement required New Bulk Storage Tanks 25 Paint Stripping 50 Small Cracks, Spalling 75 Aging Infrastructure 100 Inoperable, No Replacement Parts

Criticality Scoring (Vertical Assets) Capacity Affected (20%) Redundancy (20%) ≤ 35 MGD Lost (<5%) = 10 Full Backup = 20 36 - 69 MGD Lost (7-9%) = 30 Partial Backup = 50 70 - 139 MGD Lost (9-18%)= 50 140 - 279 MGD Lost (18-36%) = 70 ≥ 280 MGD Lost (>36%)= 100 Shared, Not Redundant = 80 Dependent = 100 Water Quality/System Impact (40%) Outage Duration (20%) Mild Impact = 20 ≤ 2 Days = 10 Operational Hindrance = 50 3 - 15 Days = 40 Major Impact = 80 16 - 29 Days = 70 Mandatory = 100 ≥ 30 Days = 100 Redundancy recognizes role of parallel and spare units or equipment Water quality recognizes imperatives vs benefits. Fluoride not necessary to treatment or water quality whereas filters are the most important barrier in the treatment process and are mandatory

condition Scoring (yard piping) CONDITION PARAMETERS & WEIGHTING SYSTEM Age (50%) Pipe Repairs (25%) Based on # Repairs in Last 10 Years < 1959 = 100 1960 – 1969 = 90 > 6 Repairs = 100 1970 – 1979 = 70 4 – 5 Repairs = 60 1980 - 1989 = 50 2 – 3 Repairs = 30 1990 - 1999 = 30 No Repairs = 0 2000 - 2009 = 10 2010 – 2015 = 0 Valve Repairs (25%)

criticality Scoring (yard piping) CRITICALITY PARAMETERS & WEIGHTING SYSTEM Capacity Affected (70%) Outage Duration (30%) Based on Percent of Total Capacity (770 MGD) Lost Based on Discussions with Field Crew and Response Time <35 MGD = 10 < 2 Days = 10 36-69 MGD Capacity Lost = 30 3 – 15 Days = 40 70-139 MGD Capacity Lost = 50 140-279 Capacity Lost = 70 >280 MGD Capacity Lost = 100 16 - 29 Days = 70 ≥ 30 Days = 100

Scoring Sheet

Low Risk Medium Risk High Risk Facility risk matrix (0-25) (26-50) (51-75) (76-85) (86-100) (0-30) Low Risk (31-50) Medium Risk (51-70) High Risk (71-100)

Plant 1 – Facility risk matrix

Plant 2 – Facility risk matrix

YARD PIPING

Cip development CIP Scheduling Considerations Existing CIP projects Combined Facilities into Prioritized Projects Prioritized Facilities Based on Risk Scores Developed OPCCs by Facility Integrated Projects into CIP Schedule CIP Scheduling Considerations Existing CIP projects Constructability Water production capacity Projected water demands Capacity required to be off-line during construction 100 MGD of excess capacity from October through June 35 MGD of excess capacity from July through September

Combined Facilities into Prioritized Projects Cip development Combined Facilities into Prioritized Projects Developed 34 CIP Projects to be implemented through 2028 totaling $229M

Project implementation schedule Plant 1 Plant 2 Plant 3 Plant 4 Plant Other Rolled up capacity and costs

Project implementation schedule

2018 Wylie WTP Complex Filter System Replacements (NTMWD 441) Chlorine Improvements HSPS 3-1 (NTMWD 480) 70 MGD Plant Expansion (NTMWD 387) HSPS 2-1 Electrical Imp. (NTD 414/603) Plant 1 Rapid Mix and Sedimentation Improvements (NTD 375) Plant Wide Electrical Repairs (NTMWD 368/FNI 11 & 13) Filter Underdrain Imp. & BAF Conversion (NTD 434)

2019 Wylie WTP Complex Chlorine Improvements Expand HSPS 3-1 (NTMWD 604) CW 3-1 (NTMWD 397) Filter Underdrain Imp. & BAF Conversion (NTD 434) 70 MGD Plant Expansion (NTMWD 387) HSPS 2-1 Electrical Imp. (NTD 603) Rockwall CW & HSPS Rehabilitation (NTMWD 608/FNI 15) Plant 2 Water (FNI 4) Plant 1 Rapid Mix and Sedimentation Improvements (NTD 375) Plant 2 Filter Repairs; Backwash and Clearwells (NTD 610 & 618/FNI 2)

Used Risked Based Approach to prioritize renewal of assets summary Used Risked Based Approach to prioritize renewal of assets Inventoried assets and conducted site visits Applied condition and criticality score Prioritized improvements Developed cost estimates Combined improvements into prioritized projects Incorporated projects within NTMWD’s existing CIP Continually revaluate implementation schedule insuring sufficient capacity

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