TRANSPORTATION RESEARCH BOARD. The Renewal of Stormwater Systems Using Trenchless Technologies. Wednesday, March 6, :00-3:30 PM ET

Transcription

1 TRANSPORTATION RESEARCH BOARD The Renewal of Stormwater Systems Using Trenchless Technologies Wednesday, March 6, :00-3:30 PM ET

2 The Transportation Research Board has met the standards and requirements of the Registered Continuing Education Providers Program. Credit earned on completion of this program will be reported to RCEP. A certificate of completion will be issued to participants that have registered and attended the entire session. As such, it does not include content that may be deemed or construed to be an approval or endorsement by RCEP.

3 Purpose Discuss NCHRP Synthesis Report 519: The Renewal of Stormwater Systems Using Trenchless Technologies. Learning Objectives At the end of this webinar, you will be able to: Describe the current trenchless renewal methods and their state of the practice Differentiate between each method and when they are applicable

4 The Renewal of Stormwater Systems Using Trenchless Technologies Presented by: David C. Ward, PE, LEG Moderated by: Mohammad Najafi, PhD, PE

5 Synthesis Objectives Provide an understanding of the successful practices and associated limiting factors for using trenchless technologies to renew stormwater facilities. Characterize the decision criteria used by facility owners when choosing a renewal method. Characterize how state departments of transportation (DOTs) and local agencies are using trenchless technologies. Summarize new, emergent, and underutilized methods and technologies that might be used in highway applications and suggest further research needs.

6 Webinar Learning Objectives Differentiate between each method and when they are applicable Understand current trenchless renewal methods for stormwater systems and their state of the practice

7 Background Types of trenchless renewal methods Outline Emerging methods DOT current practices and experiences Conclusions\Summary

8 Background Why Trenchless Renewal? Facilities reaching or exceeding their design life. Structural/Functional Repairs Minimize negative impacts and maximize the cost benefits Photo: Ohio Department of Transportation

9 Trenchless Renewal Extend service life: Corrosion, abrasion, erosion, infiltration/exfiltration Structural repair/improvement Improve hydraulic capacity (sometimes) Limit surface disruption by moving work outside of travel lanes

10 Stormwater Application 12 in to 12 foot diameter Corrugated metal, concrete, plastic and brick pipe Circular and non-circular cross-sections Spot repair to thousands of linear feet

11 Trenchless Renewal versus Installation Trenchless Renewal: Upgrading, rehabilitating, repairing, and renovating the performance and increasing the design life of existing stormwater facilities using trenchless technology. Trenchless Installation: Constructing a new stormwater conveyance system to replace an existing stormwater facility along a new alignment using trenchless technology such as pipe ramming, pipe jacking, auger boring, microtunneling, or horizontal directional drilling.

12 Cured-inplace pipe (CIPP) Sliplining (SL) Modified sliplining (MSL) In-line replacement (ILR) Spray-inplace pipe (SIPP) Close-fit pipe (CFP) Types of Trenchless Renewal

13 Cured-in-place pipe (CIPP) Insertion, expansion, and curing of a flexible fabric and a thermosetting resin lining system (hot water, steam, UV). Up to 108-inch typical (120-inch has been completed) Maximum length, depending on diameter 1,000 to 2,000 feet

14 Cured-in-place pipe (CIPP) Existing Pipe Type Concrete Steel Plastic Brick Installation of a 60-inch diameter CIPP liner using the air inversion method (Courtesy: Michels Corporation).

15 Cured-in-place pipe (CIPP) ADVANTAGES CHALLENGES Small construction footprint. Excavation typically not required. Grouting not required. Minimal reduction in culvert size. No joints. Accommodates most bends. Noncircular and varying cross-sections. Flow bypass required. Typically manufactured for specifically for each project. Toxic resins associated with some variants. Capture and disposal of cure water requires additional consideration. Relative high volumes of steam and water required for some methods.

16 Sliplining (SL) Insertion of new smaller diameter pipe into the existing pipe. Typically includes grouting the annular gap. Commonly new pipe is HDPE or PVC. Up to 160-inch Lengths up to 1,000 feet

17 Sliplining (SL) Existing Pipe Type Concrete Steel Plastic Brick Sliplining a culvert (Courtesy: Advanced Drainage Systems, Inc.).

18 Sliplining (SL) ADVANTAGES Flow bypass not always required. Structural renewal. Can accommodate large radii bends. Noncircular and varying cross-sections CHALLENGES Large insertion pits and construction area typically required. Can be mitigated with use of segmental pipe. Limited to smallest diameter of existing pipe. Excavation may be required. Bulkheading and grouting of annulus requires additional considerations.

19 Modified sliplining (MSL) Construction of a new liner for existing pipes 48-inch-diameter or larger and noncircular shapes. Includes spiral wound lining, pipe panels, pipe segments, and split-can liner. Personnel accessible size (48-inch or larger up to 14 feet). Length about 1,000 feet for spiral wound, no limit on other variants. Commonly grouted annular space.

20 Modified sliplining (MSL) Existing Pipe Type Concrete Steel Plastic Brick Spiral-wound liner (Courtesy: Contech Engineered Solutions, Inc).

21 Modified sliplining (MSL) ADVANTAGES Flow bypass not always required. Structural renewal. Smaller construction footprint. Noncircular and varying cross-sections. Accommodates some bends. Grouting not always required. CHALLENGES Specialized equipment needed for some products. Excavation may be required at some bends. Typically manufactured for specifically for each project.

22 In-line replacement (ILR) In situ replacement of the existing pipe. Common methods include pipe bursting, pipe reaming, pipe eating, and pipe ejection/extraction. Pipe bursting Split and push outward Mainly replacing plastic pipe, up to 36-inch and 1,000 feet Pipe removal Reaming/crushing into small pieces or pushing/pulling intact pipe sections out of the ground. Pipe reaming (HDD - limits), Pipe eating (microtunneling - limits), Pipe ejection (thrust capacity of original pipe, length, diameter, backfill, etc.)

23 In-line replacement (ILR) Existing Pipe Type Unreinforced or lightly reinforced concrete Steel Plastic Completed pipe bursting of a CMP (Courtesy: Hammerhead Trenchless Equipment).

24 In-line Replacement (ILR) ADVANTAGES Structural renewal. Can upsize existing pipe size. Accommodates some bends. CHALLENGES Flow bypass typically required. Larger construction footprint. Excavation may be required. Can damage adjacent structures and improvements. Not suitable for all soil conditions. Can exaggerate line and grade defects.

25 Spray-in-place pipe (SIPP) Sprayed cementitious or polymer liner for existing pipes. Includes lining for structural and non-structural renewal. Clean pipe and bypass flows Diameters 3 to 276 inches Lengths up to about 1,500 feet

26 Spray-in-place pipe (SIPP) Existing Pipe Type Concrete Steel Brick Example of cementitious SIPP (Courtesy: Centri-Pipe).

27 Spray-in-place pipe (SIPP) ADVANTAGES Small construction footprint. Noncircular and varying cross-sections. Can incorporate reinforcement. Larger diameter can be accommodated. Protects against corrosion. CHALLENGES Flow bypass required. Specialized equipment and training required. Surface preparation is critical.

28 Close-fit pipe (CFP) Installation of a new liner using the fold and formed, drawdown, rolldown, or similar process. Deformed and reformed, up to 60-inch diameter, no bends. Folded and formed, up to 30-inch diameter, up to 30 degree bends. Maximum length about 2,500 feet.

29 Close-fit pipe (CFP) Existing Pipe Type Concrete Steel Plastic Brick Deforming the HDPE pipe in a reduction dye (Courtesy: City of Fort Collins).

30 Close-fit pipe (CFP) ADVANTAGES Annular grouting not required. Structural renewal. Accommodates some bends. CHALLENGES Flow bypass required. Infiltration sealed Larger construction footprint. Limited to circular cross-sections.

31 Emerging Methods Variations of ILR using pipe ramming Pipe crushing steel wedges inside rammed casing Pipe swallowing engulf existing pipe and use second piece of equipment to break pipe to facilitate removal (Courtesy: HammerHead Trenchless Equipment).

32 Emerging Methods Geosynthetic cementitious composite mats Personnel accessible pipes Similar to invert paving Flexible cement impregnated cloth with a PVC backing. Secured and hydrated Steel-reinforced composite system Personnel accessible pipes Continuously wrapped, high strength, steel wires embedded in a spin-cast or spray-applied cementitious or polymeric matric sandwiched between two epoxy-impregnated, fiberreinforced polymer sheets.

33 DOT Current Practice and Experience Synthesis goal to answer questions regarding: Relative Frequency of Use Decision process to use trenchless renewal Method selection process Relative use and satisfaction with the methods Costs and degree that costs are tracked

34 DOT Current Practice and Experience Synthesis Literature search Questionnaire Interviews

35 Experience

36 Experience with Trenchless Renewal 40 Respondents

37 Breadth of Experience 37 Respondents 60% have experience with 2 or fewer methods 40% have experience with 3 or more methods

38 Methods and Frequency Used

39 Frequency Various Methods are Used 36 Respondents Does not consider the number of projects performed.

40 Experience with Various Methods 37 Respondents

41 Relative Frequency Methods are Used 37 Respondents

42 Satisfaction with Methods Used

43 Relative Satisfaction 36 Respondents 100% = Always 0% = Never

44 Increasing Trenchless Renewal Use

45 Experienced Agencies 37 Respondents Typical cost information Agency experience with applicable methods (case studies) Decision criteria used by facility owners Limiting factors to the applicability of specific methods Emergent technologies

46 Non-experienced Agencies 4 Respondents

47 Reasons agencies elect not to use trenchless

48 Experienced Agencies 37 Respondents Existing pipe condition Reduction in hydraulic capacity Economics/Costs

49 Non-experienced Agencies 4 Respondents Reduction in hydraulic capacity not acceptable Limited organization experience Preference for new construction Uncertainty regarding design life/performance of trenchless methods Condition of existing pipe

50 Method Selection

51 Standardized Process (Y/N) 4 Respondents (Yes) and 34 Respondents (No) Experience In-house expert/consultation Own equipment/crews

52 Reasons for Using Trenchless Renewal

53 Reasons for using trenchless renewal 34 Respondents Height of fill (cover) over the structure Limiting surface disruption Perceived economic/cost benefit Faster than open-cut Temporary or permanent deferral of constructing a larger replacement pipe

54 Temporary and Structural Renewal 35/36 Respondents Trenchless renewal is commonly (70%) considered to be a permanent repair rather than a temporary repair to defer replacement. Trenchless renewal is commonly (74%) considered to be a structural repair

55 Defects Commonly Mitigated and Satisfaction

56 Defects Mitigated 36 Respondents Corrosion Leaks/infiltration Loose or open joints Crack, breaks, or splits

57 Satisfaction Mitigating Defects 38 Respondents

58 Costs

59 Frequency Cost Overruns Occur 32 Respondents

60 Sources of Claims Two most common reasons for claims: Difference in existing pipe condition Differing groundwater/soil conditions Fourteen Comments: Existing pipe condition and/or size different than anticipated (three respondents) Differing site conditions (two respondents) Additional liner thickness required Wrong method selected for conditions Difficulty with the annular void filling No claims on trenchless renewal projects (6 respondents)

61 Conclusion/Summary

62 Webinar Learning Objectives Differentiate between each method and when they are applicable Understand current trenchless renewal methods for stormwater systems and their state of the practice

63 Summary Trenchless renewal methods are commonly considered to be permanent (70 percent) rather than as a temporary repair to defer replacement. Trenchless renewal is also commonly considered to be a structural repair (74 percent). 89 percent of respondents overwhelmingly relied on previous experience, in-house experts, or the fact that they had their own equipment and experienced crews to decide on which trenchless method to use.

64 Summary The four most common reasons for using trenchless renewal were identified as: Height of fill (cover) over the structure, Limiting surface disturbance, Perceived economic/cost benefit, and Faster than open-cut.

65 Summary The three most common reasons for DOTs with trenchless renewal experience for not using trenchless renewal when it is technically feasible were identified as: Condition of existing pipe, Reduction in hydraulic capacity not acceptable, and Economics/costs.

66 Summary The surveyed DOTs have the most experience with sliplining (SL) (89 percent), cured-in-place pipe (CIPP) (62 percent) and spray-in-place pipe (38 percent). The respondents are generally satisfied with SL (88 percent) and CIPP (90 percent). The reported satisfaction rates for the other methods may not be representative because they are not frequently used.

67 Summary The respondents are generally satisfied or very satisfied with the ability of trenchless renewal to mitigate the common defects, such as corrosion, leaks/infiltration, loose/open joints, and cracks/breaks/splits. The most common cause of cost overruns and claims is changed or differing conditions associated with the existing pipe (59 percent). Sixty-four percent of respondents indicated that cost overruns were generally less than 10 percent of the original project cost.

68 Today s Speakers Mohammad Najafi, Center for Underground Infrastructure Research and Education, University of Texas at Arlington, najafi@uta.edu David Ward, Shannon & Wilson, Inc., dcw@shanwil.com

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70 Receiving PDH credits Must register as an individual to receive credits (no group credits) Credits will be reported two to three business days after the webinar You will be able to retrieve your certificate from RCEP within one week of the webinar

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