TRENCHLESS WATER MAIN REHABILITATION DESIGN CONSIDERATIONS. V. Firat Sever PE, PhD Project Manager and Senior Engineer. August 28, 2014 Columbus, Ohio

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1 TRENCHLESS WATER MAIN REHABILITATION DESIGN CONSIDERATIONS V. Firat Sever PE, PhD Project Manager and Senior Engineer August 28, 2014 Columbus, Ohio

2 Water Main Investment Needs Source: AWWA Buried No Longer: Confronting America s Water Infrastructure Challenge

3 Water Quality Water quality degrades in distribution systems Most rehabilitation methods substantially increase water quality Issues with cement linings exposed to soft water or premature curing of polymers

4 Water Loss

5 Structural Integrity Avoid failure Depends on the lining type Class II and III (AWWA) linings are semi-structural Class IV linings are fully structural

6 Catastrophic Failure Image source: Washington Post

7 Not-So-Catastrophic Failure

8 Hydraulic Capacity

9 Basis of Water Main Rehabilitation Preserve/improve water quality Prevent water loss in the distribution system Prevent structural (catastrophic) failure Improve hydraulic capacity

10 Improved Asset Management Condition assessment/rehabilitation plan WERF s 10 step approach for water/wastewater facility asset management

11 Why Pipes Deteriorate? Age Pipe materials Soil conditions Installation quality Groundwater table Conveyed fluid Deleterious chemicals in soil/groundwater Traffic and other loads Age based decisions ignore these effects!

12 Issues w/ Open Cut Replacement Design life = 70 years (high end) Replacement rate = 0.5 % or typically less Economic cost Impact damage Social cost Feasibility

13 Trenchless Rehab Cost Factors Host pipe condition Soil properties Traffic Pipe size Market conditions Design standards Number of valves, fittings, service connections Contractor availability/bid competitiveness Groundwater

14 Cement Mortar Lining Oldest method of water main relining May provide structural support with steel fiber reinforcement Issues with soft waters Image Source: Cement Lining Corp International

15 CIPP Source of Images: Insituform Technologies

16 Slip-lining

17 Spray-on Linings (Polymer) Image courtesy of WRc - UK Image courtesy of Hydra Tech Engineered Products, LLC

18 Lining Thickness Uniformity

19 Trenchless Replacement Where rehabilitation unfeasible due to host pipe conditions Upsizing needed hydraulic capacity issues Competitive pricing Methods include pipe bursting and pipe eating Replacement pipe materials include HDPE, PVC, DI Source of Image: TT Technologies

20 AWWA M28 Rehabilitation of Water Mains Structural Class Description Examples Class I Linings Class II Linings Class III Linings Class IV Linings Non-structural serves as barrier to preserve water quality Close-fit semi-structural linings. Could span holes, gaps. Semi-structural. Could withstand buckling. Fully structural. Essentially pipe within pipe. Cement mortar, thin applied (1 mm) spray-on polymer (e.g. epoxy, polyurethane) Thick applied spray-on polymer, cement mortar? Thick applied spray-on polymer, thin wall slip-liners CIPP, slip-lining

21 Buckling Pipe wall collapse Critical if there is a hole on the host pipe and pressure is low Fracture due to excessive bending Number one reason for small diameter cast iron pipe failure (O Day, 1986) Skallerud et al

22 Flexible vs. Rigid Pipe contd. Shearing Forces Shearing Forces

23 Lined Pipe Can be a complex system of rigid host and flexible liner (e.g. HDPE installed in cast iron) Adhesion/Contact mechanics Host pipe condition Site specific

24 Adhesion Stronger = better?

25 Pipe Bending

26 Epoxy Lined Pipe

27 Failure Mode of Plastics RULE OF THUMB = USE 50 PERCENT OF SHORT TERM MODULUS OF ELASTICITY FOR DESIGN LIFE PERFORMANCE

28 Water Loss

29 Hydraulic Capacity After Lining

30 Experimental Results

31 Method Selection Criteria Trenchless Rehab (Lining) Trenchless Replacement Open cut Replacement Project Objective Feasibility Cost (direct and social) Service Connections/Valves System Hydraulics Host Pipe Condition Other (e.g. contractor availability, bonding, insurance, regulatory) Prepared for Teaching & Educational Purposes Only; 31

32 Material Selection Criteria CIPP Cement SIPP (Polymer) Project Objective Feasibility Host Pipe Condition Cost Close fit Slip liner FRP HDPE PVC HDPE PVC Service Connections /Valves Prepared for Teaching & Educational Purposes Only; No Other Use Permitted

33 Installation Access Pit

34 Installation Bypass

35 Installation Bypass contd.

36 Hydraulic Modeling Analyze pre/post rehabilitation system hydraulics Prioritize rehabilitation Pressures Water quality Fire flow

37 Hydrant Flow Test

38 Mapping/GIS Pipe size: 6 inch Material: CIP Epoxy Lined (2013)

39 Regulatory Most water main linings on the North American market achieved NSF 61 OEPA approves trenchless water main rehab

40 Conclusions Rehabilitation by relining: Will preserve/improve water quality Will improve structural integrity Will prevent water loss Can save significantly Hydraulic capacity?

41 Conclusions contd. Hydraulic capacity: Depends on the host pipe and initial design conditions Will likely improve existing capacity Will likely reduce design capacity High strength linings w/ high DR preferable Structural Integrity: Complex Need to analyze host pipe, site, soil, etc. Class I,II, III might serve the needs There is no silver bullet - sound engineering needed!

42 Questions? V. Firat Sever, PhD, PE Senior Engineer/Project Manager American Structurepoint (O) (M)