Assessing Salem s Oldest Transmission Main for Seismic Resiliency

Transcription

1 Assessing Salem s Oldest Transmission Main for Seismic Resiliency ASSESSING AND DEVELOPING OPTIONS TO REDUCE VULNERABILITY OF AGING CRITICAL INFRASTRUCTURE Presented by Troy Bowers, PE Jeff Jones, PE

2 PROBLEM STATEMENT: Problem: o o Leaking 7.5 mile, 80 year old Line 1 transmission main with leaking joints vulnerable to seismic failure Need: o Inspect and evaluate Line 1 o o o Estimate remaining service life Recommend improvement/replacement options Prioritize repairs 2

3 SALEM, THE CHERRY CITY AND OREGON S CAPITOL 3

4 North Santiam River is Salem s Drinking Water Source Intake and Treatment Plant Located near Stayton Water is conveyed 11 miles from plant to Turner Via 69-inch, 54-inch and 36-inch supply mains with 75 MGD capacity 4

5 A LITTLE HISTORY OF SALEM WATER Prior to 1930 s, Salem s drinking water source was the Willamette River Early 1930 s, City takes over private water system 1936, City developed plans to tap Mountain Water from the North Santiam Pump House in the 1920 s 5

6 BACKGROUND: DRINKING WATER SOURCE North Santiam River Watershed South Santiam River is a Tributary of the Willamette River 6

7 DEVELOPING NEW MOUNTAIN WATER TRANSMISSION FACILITIES Project map from 1936 Line 1 Design Drawings Line 1 constructed in miles of Steel and reinforce concrete pipe Gravity system 7

8 MAJOR IMPROVEMENTS TO TRANSMISSION FACILITIES 69 MAIN (LINE 3) FRANZEN RESERVOIR Project map from 1936 Line 1 Design Drawings 1952, 100 MG Franzen Reservoir and control valve station 1958, 54-inch diameter Line 2 constructed 69 MAIN 2003, Portions of Line 1 replaced with 69-inch diameter pipeline 8

9 REMAINING PORTION OF 36 LINE 1 OF MOST CONCERN Water right and funding issues - remaining 69-inch transmission main on hold Reliability of remaining 7.5 miles of Line 1 9

10 Now add the Cascadia Subduction Zone Cascadia subduction zone poses a major geological hazard to Oregon Oregon s building codes were updated starting in1994 to address this threat Majority of Northwest's infrastructure constructed prior to

11 OREGON RESILIENCY PLAN Prepared by the Oregon Seismic Safety Policy Advisory Commission as authorized by the Oregon House Infrastructure interruptions may last from 18 to 36 months or more Be prepared to be self-sufficient for far longer than the commonly advised 72 hour period 11

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13 MSA AUTHORIZED IN AUGUST 2009 TO PERFORM EVALUATION MSA LINE 1 EVALUATION TEAM: Murray, Smith & Associates, Inc. (MSA) Cascade Corrosion Consulting Services, Inc. (CCCS) Bravo Environmental 13

14 LINE 1 ASSESSEMENT PROJECT SCOPE Review and evaluate existing info Excavate select areas Corrosion assessment of steel pipe sections Internal Pipeline Inspection using video Leakage testing using City SCADA system Localized leak testing using ground microphone Improvement Recommendations and prioritization Pipeline Assessment Report 14

15 APPROXIMATELY 75% OF LINE 1 IS CONCRETE 36-inch Diameter / Reinforced Concrete Pressure Pipe / 8-foot lengths Exterior appears sound / no exposed steel reinforcement / no spalling or cracking 15

16 EXTERNAL CONCRETE PIPE ASSESSMENT: UNUSUAL CONCRETE PIPE JOINT CONFIGURATION Factory installed bell end Bell end Collar Field applied grout Spigot end Grouted joints with no flexibility 16

17 CONCRETE PIPE JOINTS CONSTANTLY REPAIRED City crews keep stainless steel repair sleeves on hand 17

18 25% OF LINE 1 IS WELDED STEEL 36-inch diameter / ¼-inch thick steel Buried coated with wrapped asphaltic coal tar Above grade coated with red primer/alkyd coating 18

19 CORROSION ASSESSMENT : TEST STATIONS INSTALLED Salem crews assisted in installing six test stations George Richards of CCCS / thickness of coating and pipe walls / measuring soil properties 19

20 CORROSION TESTING At each test station excavation, perform inspections: Evaluate coating Evaluate condition of the pipe and measure thickness Measure pipe to soil potential Measure Soil ph and Redox for determining soil resistivity 20

21 CORROSION TESTING Using the test stations CCCS performed the following tests: Pipe Continuity Over-the-line potential measurements to determine areas of highest corrosion 21

22 INTERNAL PIPELINE INSPECTION Concrete pipe lining / skim coat Steel pipe / asphaltic coal tar lining / signs of deterioration and corrosion 22

23 6 PIPELINE ACCESS PORTS FOR VIDEO INSPECTION WITH WATERLINE DRAINED Two new 24-inch access ports Four existing 18-inch ports 23

24 INTERNAL PIPELINE INSPECTION COMPLETED BY BRAVO ENVIRONMENTAL Video cam mounted on a Storm Drain Tractor No. 1 (1956) No. 2 (1965) Tight fit at 18-inch access ports

25 INTERNAL PIPELINE INSPECTION Locals took an interest in the operation 25

26 14,000 OF 40,000 FEET WAS VIDEO INSPECTED Kelly Butte (1959) Moe Hill (1996) Willamette Heights (1962) South 57th Steel Pipe South Hills (1982) No. 1 (1956) Concrete Pipe South 67th (1967)

27 CONCRETE PIPING Kelly Butte (1959) Moe Hill (1996) Willamette Heights (1962) South 57th South Hills (1982) No. 1 (1956) Joint separating No. 2 (1965) South 67th (1967)

28 STEEL PIPING South Hills No. 2 (1982) Lining is failing No. 2 (1965) South 67th (1967)

29 PIPELINE LEAK TESTING AND DETECTION Leakage Testing SCADA system showed average loss of 0.94 MGD over 19 day period Leak Detection American Leak Detection / concrete pipe alignment Ground microphones Surface water along the pipe alignment was tested for chlorine South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

30 ANALYSIS, FINDINGS, REHAB OPTIONS, RECOMMENDATIONS, AND PRIORITIES South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

31 SUMMARY OF FINDINGS: CONCRETE No. Structurally 1 in good condition Pipe joints cracked and failing grout Ground No. water 2 infiltrating Chlorine detected in road ditches indicating chronic leakage Many leaking concrete pipe joints appear at roadway and railroad crossings South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

32 SUMMARY OF FINDINGS: STEEL Exterior appeared to be in good condition Buried No. 1 coal tar coating appears intact Minor damage from tree roots, irrigation piping, or previous excavation No. 2 Interior surface has moderate to extensive corrosion Corrosive soil conditions throughout the pipe sections surveyed. South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

33 SUMMARY OF CORROSION ASSESSMENT Pipe Continuity: Confirmed through most of the steel portions except at Geren Island Pipe-to-Soil Potential: o o No. 1 Analysis showed areas of high probability of corrosion to occur No. 2 Western section of steel piping showed 90% probability of corrosion activity Soil Resistivity, ph and Redox: Western section of steel piping susceptible to failure due to seasonal soil corrosion or oxidation reduction corrosion South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

34 CONCLUSIONS AND RECOMMENDATIONS Line 1 appears to have reached the end of its service life Line 1 is vulnerable to failure during a seismic event, due primarily to the No. 1 grouted concrete pipe joints Installation of an external corrosion protection system to preserve the steel pipe is recommended No. 2 Recommendations include a combination of trenchless pipe rehabilitation systems and pipe replacement Rehabilitation methods to be further evaluated during pipe design South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

35 PIPE REHABILITATION OPTIONS: NSF Structural Lining Technology: o o o o Sliplining methods with PVC, HDPE, or FRP No. 1 InsituMain by Insituform, installed similar to cured-in-place pipe (CIPP)systems No. 2 InsituGuard by Insituform, installed similar to sliplining methods Fiber Reinforced Polymer (FRP) systems such as QuakeWrap, applied by hand South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

36 PIPE REHABILITATION OPTIONS (CONT.) Non-Structural Lining: o o Conventional cured-in-place pipe (CIPP). No. 1 Cement Mortar and Epoxy Lining Pipe Replacement/Realignment: o o No. 2 Pipe replacement through long stretches of agricultural land potentially less costly than trenchless rehabilitation Reroute Line 1 through the City of Stayton, locating it within the public right-of-way South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

37 ASSESSMENT AND RECOMMENDATIONS South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

38 LEAK DETECTION: RURAL FARM LAND South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

39 LEAK DETECTION: CITY OF STAYTON South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

40 LEAK DETECTION: STAYTON AND GEREN ISLAND South Hills No. 2 (1982) No. 2 (1965) South 67th (1967)

41 REHABILITATION PRIORITY METHODOLOGY Five criteria used for determining priority areas of pipeline rehabilitation Relative Weight Fixed Weight Description 10 5 Risk to Life 9 5 Risk to Property 6 5 High Leakage Rate 6 5 Impact to Public: Economic, Traffic Disruption, etc. 5 5 Good Accessibility for Pipe Rehabilitation No. 2 Work (1965) South 67th (1967)

42 REHABILITATION PRIORITY ANALYSIS Two screening matrices with variable Rate and Fixed Criteria were used (variable rate matrix shown) Description South Hills No. 2 (1982) South 67th (1967)

43 REHABILITATION PRIORITY COMPARISON Description South Hills No. 2 (1982) South 67th (1967)

44 REHABILITATION: Prioritized List of Work Order of Priority Proposed Work Components 1 Line concrete pipe located under buildings and homes 2 Line concrete pipe located under roadways and adjacent to railway 3 Line remaining concrete pipe 4 Steel pipe section under railway Interior lining and exterior cathodic system 5 Exposed steel pipe under waterways Interior lining and exterior cathodic protection 6 Steel pipe interior lining 7 Steel pipe with coating damage in Pioneer Park (Stayton)- Exterior cathodic protection 8 Western section of steel pipe near dairy farm Exterior cathodic protection 9 Above ground and remaining steel piping Exterior corrosion and cathodic protection 44

45 SUMMARY Assessment provides the City with a thorough understanding of their supply main s condition Rehabilitation priorities allow the City to best manage risk, invest limited financial resources, and sustain useful function of Line 1 until City is able to replace it Recommended additional assessment work on Line 1 includes further analysis of the steel pipe for cathodic protection Recommended further examination of trenchless pipe rehabilitation options applicable to large diameter potable water transmission mains 45

46 SUBSEQUENT WORK AND CURRENT STATUS In 2013, isolation valves where cut into Line 1 and Line 2 Cutting in 54-inch butterfly valves City is considering No. 2 their rehabilitation South Hills No. 2 (1982) (1965) and replacement options for Line 1 Cutting in 36-inch butterfly valves with custom fabricated transition couplings

47 QUESTIONS? Presented by Troy Bowers, PE Jeff Jones, PE