Leak Location Geosynthetic Materials in Base Liner Systems. NY Federation SWANA. May, 2014

Transcription

1 Leak Location Geosynthetic Materials in Base Liner Systems NY Federation SWANA May, 2014

2 Different ELI Surveys A. Covered Electrical Liner Integrity (ELI) Survey Dipole Method Suitable for water or soil covered surveys. ASTM D7007 ASTM D6747 B. Exposed ELI Survey Water Puddle/Water Lance Method Suitable for exposed geomembranes using water ASTM D7703/D7002 Spark Testing Method Suitable for exposed geomembranes. ASTM D7240 2

3 LANDFILL SYSTEMS

4 Subtitle D liner system Solid Waste Leachate Removal System (i.e. perforated pipe network) EPA Minimum Technical Guidance Filter Layer 12 Permeability 1x10-2 cm/sec Leachate Collection Geomembrane 30 mils if HDPE then 60 mils 24 Permeability 1x10-7 cm/sec Soil Subgrade Compacted Clay Liner (CCL)

5 Subtitle D Liner System Geosynthetic Alternatives Geocomposite: Replace filter layer and leachate collection layer. 12 GCL: Replace CCL as 24 design considerations allow and potentially reduce compaction and CQA testing. Solid Waste Filter Layer Permeability 1x10-2 cm/sec Why? Perform better than earthen materials More cost-effective to install Extend life of cell more open air space Leachate Collection Geomembrane Permeability 1x10-7 cm/sec Soil Subgrade Compacted Clay Liner (CCL)

6 Geosynthetic Products for Landfills Geomembranes Colored Surface to Reduce Wrinkles Improved anti-oxidant package Increased multi-axial flexibility to resist localized damage Geosynthetic Clay Liners Intimate contact with geomembrane Reduce wrinkles with weight of clay Geocomposites Higher Flow to quickly determine defect in primary liner Faster operation cycle for testing period 3

7 TRIPLANAR & TRI-AXIAL HIGH FLOW GEOCOMPOSITE

8 DRAINAGE LAYER OBJECTIVE Liquid / Rain Find geomembrane defects with geocomposite that has unconfined flow

9 Tri-planar and Tri-axial Geonet Structures Regulations have specified ALR in permit, determine if ALR is exceeded to bring cell back to compliance Find defects in primary liner quickly so landfill can commence operation

10 GEOSYNTHETIC CLAY LINERS GEOMEMBRANE SUPPORTED

11 GCL Product Types GSE BentoLiner - Fabric Encased GCL Nonwoven geotextile Sodium bentonite Woven or nonwoven geotextile GSE GundSeal - Geomembrane Supported GCL Sodium bentonite Geomembrane Giroud Leakage Equation and Contact Factor-C: QGM = C [ (hw / t)0.95] a0.1 hw 0.9 ks 0.74 Where C varies from 0.01 (excellent) to 1.15 (poor contact)

12 Geomembrane Supported GCL Intimate Contact Geomembrane Sodium Bentonite Spunbonded Geotextile Provides swelling and sealing of bentonite clay with the chemical resistance and impermeability of HDPE geomembrane 15 mil to 80 mil smooth or textured geomembrane Installed in a single composite mode or encapsulated mode

13 Geomembrane Supported GCL - Advantages Sodium bentonite Single product installation EPA/Regulatory acceptance as composite liner since 1994 Improved performance over GM/CCL composite liners Up to 150 times less leakage than CCLs (Thiel et al., 2001) Typically results in cost savings vs. CCL or GM/GCL system Geomembrane

14 Geomembranes

15 Raw Material Selection Resin Polymer Additives Carbon Black

16 Selecting the Right Resin Break Elongation Stress Crack Resistance Multi-axial Resistance

17 Manufacturing Process

18 Round Die Technology Example: Textured 60 mil (1.5mm) White Leak Location Liner White/Black/Green/Textured 5 mils ( mm) Standard Black 52 mils ( mm) Textured Conductive Layer 3 mils (0.076 mm) Why Co-Extrusion Manufacturing Process? Top surface can be black, white, or green Top surface may also be textured or smooth Integral conductive layer enables spark testing after installation

19 White Surfaced Geomembrane Visual CQA Damage Detection Visual Aid in Welding

20 White Surface Technology 1. Improved damage detection 2. Cooler Surface Temperature 3. Reduced subgrade desiccation 4. Reduce GCL shrinking 5. And Most Importantly 6.

21 Avoid Wrinkling Not just for aesthetics Not just aging or smoking, but prolonged exposure to sun Wrinkling is caused by expansion & contraction of HDPE from daytime / nighttime temperature changes Minimize risk of damage to liner during placement of cover soils due to wrinkles

22 Why Wrinkles Matter 1. Decreased intimate contact with subgrade decrease shear strength and increased potential leakage Giroud Leakage Equation and Contact Factor-C: QGM = C [ (hw / t)0.95] a0.1 hw 0.9 ks 0.74 Where C varies from 0.01 (excellent) to 1.15 (poor contact) 2. Creation of flow barriers and ponding Reduced effectiveness of the drainage system 3. Differential wrinkles or fishmouths increase difficulty and decrease integrity of geomembrane seam welding 4. Stress concentrations when they fold over or collapse 5. Once in place and covered they do not go away; entombed

23 Wrinkling Fix them or Live with them? Fix Them: Difficult to remove from the liner They shift and move, never recede and will return They can be entombed in cover soil They are hydraulically connected Live with them: Conductive surface integral with insulating layer (core HDPE) Otherwise most intimate contact required to provide a sensitive leak location test

24 Wrinkle Reduction Solutions Solutions: Creams no geosynthetic innovation yet Minimize wrinkles by limiting installation timeframe i.e. dusk or dawn Surgery: Cut the wrinkles and weld Minimize with white surfaced geomembrane Utilize spark test to locate all defects on exposed conductive liner; wrinkles and seams Utilize ELIS over cover soil to locate large defects, even on wrinkles and seams White Surfaced Leak Location Liner

25 CONVENTIONAL LINER INSTALLATION

26 Conventional Liner Install 26

27 Burn holes.. 27

28 Why do they Leak? 28

29 Spreading procedure as specified? What does a CQA Technician do? Geomembrane protected? CQA Tech Observe and Document Drainage aggregate within spec? Behave independently Provide Documentation that what was built is in conformance with the approved plans and specifications CQA Firm has no contractual obligation to the contractor works for the owner and/or regulator 29

30 Post-Installation Damage Dynamic fast moving conditions Liner puncture from: Dropping tools Equipment puncture Cover soil application Grade stakes Oversize particles 30

31 Leakage Increases With Head Pressure Showing ~4 mm diameter leak Plus 7 pinholes Responsible for ~30 gpad under ~2m head pressure NYSDEC 20 gpad ELIS already required In conjunction with Exposed liner test finds all defects 31

32 Occurrence of Liner Defects Survey Data - Liner Defect Occurrence, Nosko (1996) Preliminary Construction Phase Final Construction Phase Post-Construction/Early Operation 32

33 Rowe and Beck are researching wrinkles further 33

34 Do you care if it leaks? 34

35 Leak Location Liner

36 LEAK LOCATION LINER EXPOSED SPARK TEST

37 Exposed Liner Methods Using Water Water Puddle ASTM D 7002 Water Lance ASTM D 7703 Advantage: GSE Leak Location liner does not rely on water in the leak detection layer in order to perform leak survey. 5

38 Exposed Liner Method with Spark Testing Power Source Grounding Pad Test Wand Advantage: Conductive liner does not rely on water in the leak detection layer in order to perform leak survey

39 Spark Testing Near Fusion Welds False Positives: Created when electrical current passes through the weld Alerts as though a leak was found Conductive Flap Current 39

40 Exposed Flap Isolation Conductive Conductive Isolated Current 40

41 Leak Location Liner Covered Electrical Liner Integrity (ELI) Survey

42 Leak Detection - ASTM Test Methods ASTM D Standard guide for Selection of Techniques for Electrical Detection of Leaks in Geomembranes ASTM D (2011) - Standard Practice for Leak Location using Geomembranes with an Insulating Layer in Intimate Contact with a Conductive Layer via Electrical Capacitance Technique (Conductive Geomembrane Spark Test) ASTM D7002 / D Standard Practice for Leak Location on Exposed Geomembranes Using the Water Puddle / Water Lance Systems ASTM D Standard Practices for Electrical Methods for Locating Leaks in Geomembranes Covered with Water or Earth Materials

43 Leak Location Liner System - 2nd Generation 43

44 Basic Dipole Survey Method Ideal Conditions Electricity flows like water towards a hole Specialized equipment shows the direction the electricity is flowing Readings are taken in a grid pattern 44

45 Below Geomembrane Conductivity not a Concern Poor conductivity with subgrade can be local Dry subgrade, dry GCL, or a drainage net Air gaps from wrinkles and bridging 45

46 Above Geomembrane Solved by Water Dry cover soil Solved by Water Large Particles with air gaps Solved by Water Drainage Net Breaks Conductivity - Solved by Water 46

47 SKB Lansing Landfill Project 47

48 SKB Lansing Landfill Project 48

49 SKB Lansing Landfill Cross-Section Sandy Cover Soil 4 ft. (1.2 meters) Geocomposite Leak Location Liner GCL Subgrade 49

50 SKB Lansing Landfill Project 50

51 SKB Lansing Landfill Project 51

52 Geosynthetic Environmental Products Geomembranes Colored Surface to Reduce Wrinkles Increased multi-axial flexibility to resist localized damage Geosynthetic Clay Liners Intimate contact with geomembrane Reduce wrinkles with weight of clay Geocomposites High Flow to quickly determine if a leak is present Faster operation cycle for testing period 3

53 Contact Information GSE Environmental Technical Manager Northeast USA & Canada M: E: W: 55

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