Non-Destructive Testing & Assessment of Concrete Structures Case Study: St. Mary Dam Low-Level Conduit

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1 Non-Destructive Testing & Assessment of Concrete Structures Case Study: St. Mary Dam Low-Level Conduit Presented By: Clayton Weiss, P.L.(Eng.) ESRD Operations Infrastructure, Oldman Basin

St. Mary Dam - Background Constructed 1946-1951, 65 years old,

(426 m easy access via catwalk left side at 3m), 6m (20 )

2 St. Mary Dam - Background Constructed , 65 years old, high risk Low-level concrete riparian conduit, 646 meters long (426 m easy access via catwalk left side at 3m), 6m (20 ) inside Dia., m thick walls, sub-grade under 50 meters fill.

3 Management & Optimization of Aging Infrastructure Challenge: approaching end of theoretical design service life. How to determine actual remaining life, justify need for high priority funding? Extreme high costs to repair or replace. Limited funding, many competing high priority projects: What is the Level of Risk??!! Dictates when is action is required PROVE IT Design & Construction will take many years due to size and unique challenges start planning now.

4 Management & Optimization of Aging Infrastructure Current monitoring strategy: Standard Methods: Visual surface inspections, crack monitoring, leakage/seepage monitoring, Schmidt hammer testing. Very effective and essential to continue, but has limitations: Limited to surface only, no way to identify and map internal defects Limited precision, requires confirmation & quantitative data No early warning of internal degradation.

5 Management & Optimization of Aging Infrastructure How to increase level of scrutiny beyond the surface, and gather quantitative data, including: Directly measure internal quality and overall uniformity of the concrete Identify red flag defects. i.e. voids, delamination, honeycombing Confirm actual rebar arrangement (concerns regarding 1940 s construction standards). More inputs for identifying Level of Risk

6 Non-Destructive Testing Methods - Options? - 1) Schmidt Hammer Test lower precision for internal defects, needs confirmation - 2) Hammer Sounding - lower precision for internal defects, subjective, needs confirmation - 3) Ultra-Sonic Pulse Velocity (UPV) Used to assess structural integrity of concrete members in bridges, and to map extents of defects. Limitation requires 2-sided access, not possible in the case - 4) Impact-Echo Scanning LOW COST, FAST - collect ASTM approved measurements of thickness in concrete and identify and map location and extents of defects ex. Cracks, Delaminations, Voids, Honeycombing. Limited to 1 meter thickness, requires only 1-sided access YES - 5) Ground Penetrating Radar LOW COST & FAST - Identify and map first layer of rebar - YES - 6) Coring and Laboratory testing by far the most detailed, complete & precise information, but HIGH COSTS and LONG TIMELINES in concrete of questionable quality, destructive testing can be risky until condition is first assessed with methods such as #4 and #5 above.

7 Evaluate New Methods for Monitoring & Assessment of Concrete Structures Pilot Project: Evaluate the Effectiveness of Non-Destructive Testing Techniques as a useful Infra. Management Tool augment existing methods. May, 2013 Request for Proposals for Non-Destructive Testing, Impact Echo and GPR Awarded to AMEC Materials Group, Calgary. July, 2013 Field Testing program begins

8 Field Testing Program GPR Rebar Locates - 5 Sample Locations

9 Field Testing Program GPR - 5 Sample Locations

10 Field Testing Program GPR - 5 Sample Locations Results Red Flag concerns/deficiencies Reinforcing bar highly variable pattern/orientation, vertical and horizontal spacing far too wide, not close to conforming to current standards Not installed as per record drawings, record information incorrect!! Very deficient in spacing, orientation, consistency, and cover

11 Field Testing Program Impact-Echo - Sample Locations

12 Field Testing Program Impact-Echo - Sample Locations

13 Field Testing Program Impact-Echo - Sample Locations

14 Field Testing Program Impact-Echo - Results Sound Concrete Suspect/Low Quality Concrete Defective Area

15 Field Testing Program Impact-Echo - Results Defective Concrete Multiple Defective Areas

16 Field Testing Program Impact-Echo - Results Summary of Results Strong correlation with visual and hammer sounding results, >50% areas sampled were red flag concerns Sound/Good: 50% Suspect or Defective: 50% Delaminated Areas: 56% Interpretation? Next Steps? Consultant recommended collecting Core Samples for Lab Analysis to calibrate readings, Impact-Echo Proof-of-Concept, increase confidence Also Collect additional Lab data: Compressive Strength & Hardened Density, Air entrainment, Permeable void analysis Alkali-aggregate reactivity

17 Confirmation of Non-Destructive Tests - Core Sampling & Laboratory Analysis Jan., Cores Collected & Analyzed at AMEC s Lab» 3 diameter, Min. depth 200 mm

18 Concrete Coring for Lab Analysis

19 Concrete Coring for Lab Analysis

20 Concrete Condition Core Laboratory Findings and Conclusions Overall, highly variable concrete with many reasons for concern: Consistently High/Good Compressive Strength, Avg. >50 Mpa Absorption and Permeable Voids Good Consolidation Air Content Very Poor, not air-entrained, Evidence of stress due to prolonged moisture, sulphate attack, weakening structure, Poor No evidence of Alkali-aggregate reactivity, Good Evidence of expansive distress, physical defects including cracking, delamination and voids consistent with Impact Echo findings, Poor Rebar orientation, spacing and depth of cover Very Poor

21 Evaluation of Methods - Conclusions Ground Penetrating Radar Rebar Location Method Effective method for mapping rebar and cover, confirming asconstructed records, id new deficiencies. No other equivalent substitute method Fast Real-Time Results, Cost Effective

22 Evaluation of Methods - Conclusions Testing Results: Strong correlation between A) Existing Visual & Hammer Surveys, B) Impact Echo and C) Actual lab test results

23 Evaluation of Methods - Conclusions Evaluation of Method - Impact Echo Testing Method: Reliable, Effective, Immediate Results in Real Time, No Waiting, Low Cost, much cheaper than core & lab test Low Impact No Destruction and can quickly access tight spots Confirmed results from current/past methods, i.e. areas of defect Expanded scrutiny into interior of concrete, confirmed thickness Provided quantitative data to add credibility and confidence to conclusions i.e. Current Level of Risk, Remaining Service Life Limitations - Not a standalone solution for concrete evaluation, but is complementary & adds value to a comprehensive program.

24 Conclusions When used in combination with existing surface monitoring, spot core sampling and lab tests for calibration, Impact Echo and GPR are very fast, cost effective testing methods for concrete structure assessment and early detection of problems. Not a standalone solution, limitations must be understood Particularly valuable for buried sub-grade structures Adds credibility to current monitoring program and directly supports maintenance & Capital Planning processes.

25 Next Steps Expand scope of testing & evaluation: Gather more data from more locations, including bottom and top of conduit with access issues Uniformity? Areas of more severe defect, first point of failure? Risk? Continue to refine service life estimates, support Capital Planning Process Track change over time Retain a Structural Engineer to analyze the data in detail, 3 rd party opinion on current level of risk and remaining life

26 Questions?? and Thank You: Mr. Shaun Radomski, M.Sc., P.Eng. Materials Engineer AMEC Environment & Infrastructure Calgary, AB Clayton Weiss, P.L.(Eng.) ESRD Operations Infrastructure, Oldman Basin

Inspection & Maintenance of Concrete Facilities By Cheyenne Wohlford CCS GROUP, LLC

Inspection & Maintenance of Concrete Facilities By Cheyenne Wohlford 1 Introduction Most Grain Elevators were built between 1950 and 1960 with a life expectancy of 30 years. Operational changes since 1960