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An Overview of Direct-push Well Technology for Long-term Groundwater Monitoring

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  1. Welcome – Thanks for joining us. ITRC’s Internet-based Training Program An Overview of Direct-push Well Technology for Long-term Groundwater Monitoring ITRC Technical and Regulatory Guidance: The Use of Direct-push Well Technology for Long-term Environmental Monitoring in Groundwater Investigations This training is co-sponsored by the EPA Office of Superfund Remediation and Technology Innovation

  2. ITRC Member State ITRC (www.itrcweb.org) – Shaping the Future of Regulatory Acceptance Host Organization • Network • State regulators • Federal government • Industry • Consultants • Academia • Community stakeholders • Documents • Technical and regulatory guidance documents • Technology overviews • Case studies • Training • Internet-based • Classroom ITRC State Members Federal Partners DOE DOD EPA

  3. Characterization, Design, Construction and Monitoring of Bioreactor Landfills Direct-push Wells for Long-term Monitoring Ending Post Closure Care at Landfills Planning and Promoting of Ecological Re-use of Remediated Sites Rads Real-time Data Collection Remediation Process Optimization Advanced Training More in development……. Alternative Landfill Covers Constructed Treatment Wetlands Environmental Management at Operational Outdoor Small Arms Ranges DNAPL Performance Assessment Mitigation Wetlands Perchlorate Overview Permeable Reactive Barriers: Lessons Learn and New Direction Radiation Risk Assessment Radiation Site Cleanup Remediation Process Optimization Site Investigation and Remediation for Munitions Response Projects Triad Approach What’s New With In Situ Chemical Oxidation ITRC Course Topics Planned for 2006 Popular courses from 2005 New in 2006 Training dates/details at www.itrcweb.org Training archives at http://cluin.org/live/archive.cfm

  4. Presentation Overview Direct-push (DP) well technology overview Advantages and limitations Known regulatory barriers and concerns Questions and answers Comparative data between DP and conventionally drilled wells Case study highlights Health and safety Stakeholder and tribal concerns Links to additional resources Your feedback Questions and answers Logistical Reminders Phone line audience Keep phone on mute *6 to mute, *7 to un-mute to ask question during designated periods Do NOT put call on hold Simulcast audience Use at the top of each slide to submit questions Course time = 2¼ hours An Overview of Direct-push Well Technology for Long-term Groundwater Monitoring

  5. Keisha D. Long South Carolina Department of Health and Environmental Control Columbia, South Carolina (803) 896-4872 LongKD@dhec.sc.gov Meet the ITRC Instructors Bradley A. Call U.S. Army Corps of Engineers Sacramento, California (916) 557-6649 Bradley.A.Call@usace.army.mil William Major Navy Facilities Engineering Service Center Port Hueneme, California (805) 982-1808 William.Major@navy.mil

  6. What You Will Learn… • A description of direct-push well technology and equipment and installation requirements • Sampling considerations • Technology advantages and limitations • Known regulatory barriers and concerns • Comparisons between direct push and conventionally drilled wells • Case studies • Stakeholder concerns

  7. Why Monitoring Wells? • Used to collect ground water samples at a fixed location over time (short or long-term monitoring) • Types of wells and method of installation vary • Guidelines for well installation depend upon individual state regulations

  8. What are Direct-push (DP) Wells? • Installed by static or dynamic push • DP wells are smaller in diameter • Were initially deployed for short-term monitoring

  9. Potential for Dramatic Cost Savings !! What’s the Big Deal About Direct-push Wells? Why Should I Care?

  10. Annular Space Barrier States Annular space barrier Long-term permitted

  11. Direct-push Well Systems • Static force • Cone penetrometer • 10-30 ton truck • Sensors • Dynamic force • Percussion hammer • Truck mounted

  12. Advantages Less investigation derived waste (IDW) Work faster Work smarter Improve representativeness Landowner friendly Less costly Disadvantages Not applicable in some geologic conditions Regulatory restrictions Well diameter limitations Cross-contamination potential Potential for higher turbidity Performance of Technology Not accepted for long-term monitoring in most states Representative chemistry and field parameter measurements Inexpensive to install, replace, and abandon

  13. Systematic Project Planning Dynamic Work Strategies Real-time Measurement Technologies Faster The Triad Approach • Rapid installation and site characterization • Installation rate two to five times faster than conventionally drilled monitoring wells • DP wells can be integrated into a comprehensive dynamic characterization plan (e.g., the Triad approach) Uncertainty Management See ITRC Technical and Regulatory Guidance for the Triad Approach (SCM-1) and associated Internet-based training. More information is available at www.itrcweb.org under “Guidance Documents” and “Internet-based training”

  14. Adaptable to New Sampling Technologies • DP wells can be integrated with real-time measurement systems such as Membrane Interface Probes (MIPs) • The ability to acquire data in real time enhances application of Triad

  15. The primary regulatory issue concerning direct-push wells is that most states require a minimum annulus size for a monitoring well. This requirement cannot be met by the direct-push installation technique. Regulatory Issues

  16. Regulatory Concerns • Well permitting • Annular space • Well seal • Filter pack • Data acceptability • Water level data • Chemical data

  17. Examples of State Regulatory Concerns • Many states require individual variances each time a DP well installation is proposed • Florida • Casings > 4 inch and minimum grout thickness of 1 inch have limited DP installations • Illinois • Only temporary (< 1 year) installations allowable • Indiana • Using a 4-inch drive point is not acceptable • Oklahoma • Borehole requirements restrict DP use

  18. DP Technology – Overview of This Part of the Training • DP well installation • Construction • Development • Sampling • Hydraulic conductivity – comparability • Advantages/disadvantages

  19. Well Types Conventional hollow-stem auger well DP well with pre-pack screen DP well with exposed screen PVC well casing Bentonite or cement grout Bentonite seal Natural aquifer material Sand filter inside SS mesh Slotted screen Sand filter Expendable drive point

  20. DP Installation Techniques • Two general installation categories • Protected-screen • Exposed-screen • Both involve • Drive rods – typically steel • Expendable metal drive points

  21. Installation – Protected-Screen During installation After retracting drive casing • Within the drive rod • Requires seal and filter pack • Well screen protected from damage and clogging • Generally similar to conventional well installation PVC well casing Borehole with drive casing removed Drive casing Bentonite/ QuickSeal sleeve Dry Hydrated Polyethelene sleeves Compressed Expanded Foam bridge Prepack screen Expendable drive point

  22. Installation – Exposed-Screen DP well with exposed screen • Potential damage/ clogging of screen • Potential cross-contamination issues • Requires careful well development • Faster installation • Less expensive • Does not allow annular seal Natural aquifer material Expendable drive point

  23. Construction Materials • Well configuration and materials similar to conventional wells • Common casings • Schedule 40 or 80 PVC threaded or flush-jointed casings • Common sizes • ¾, 1, and 2-inch • Screens

  24. Construction Materials (continued) • Filter-pack • Pre-installed • Grout barriers • Plastic • Foam • Seal • Pre-installed • Tremie pipe

  25. Well Development • Installation alters borehole wall and adjacent formation • Development • Improves well/aquifer hydraulic connection • Removes fines from filter pack • Reduces sediment in water samples Before After

  26. Development Techniques For direct-push wells • Over pumping (purging) • Mechanical surging • Water jetting

  27. Development Pumping

  28. Sampling DP Wells • Similar to conventional wells • Purge and sample • Purge 3 to 5 casing volumes • Ensure groundwater parameters stabilize • Collect sample • Low-flow purge and sample • Similar to above, however purge at slower flow rate • No purge sampling – passive diffusion bags or snap samplers

  29. Hydraulic Conductivity Study • Participants • Stephen Bartlett (University of Connecticut) • Dr. Gary Robbins (University of Connecticut) • Dr. Mike Barcelona (Western Michigan State University) • Wes McCall (Geoprobe) • Dr. Mark Kram (Naval Facilities Engineering Service Center) • Objective • Compare hydraulic conductivity (K) measurements in DP and hollow stem auger (conventional) wells • Test Location • Port Hueneme, California

  30. Hydraulic Conductivity Study Activities • 296 pneumatic slug tests • Pumping tests • Unsteady state • Constant head steady state • Geology • Fluvial-deltaic • Sand and gravel • Fully submerged screens

  31. Variability in Hydraulic Conductivity (K) – DP Versus Conventional Wells Hydraulic Conductivity (K) (cm/sec) 0.04 0.03 0.02 0.01 0.00 ¾-inch, ASTM pre-pack, DP well 2-inch, ASTM pre-pack, DP well ¾-inch, off-shelf pre-pack, DP well ¾-inch, no filter pack, DP well 2-inch, ASTM filter pack, conventional well

  32. Conclusions • Short duration pneumatic slug tests (<3 seconds) are feasible for high K formations • K for DP and conventional wells is statistically different but comparable in magnitude • Study results documented in Navy technical report • TR-2252-ENV “Comparison of Hydraulic Conductivity Determinations in Direct Push and Conventional Wells,” Oct 2004

  33. Advantages Less investigation derived waste (IDW) Work faster Work smarter Improve representativeness Landowner friendly Less costly Disadvantages Not applicable in some geologic conditions Regulatory restrictions Well diameter limitations Cross-contamination potential Potential for higher turbidity Advantages and Disadvantages

  34. Advantage – Less Investigation Derived Waste (IDW) • Minimal cutting wastes • Fewer well development wastes • Overall, less investigative derived waste (IDW) to manage • Reduced exposure to contaminated soil • Reduced costs

  35. Advantage – Work Faster • DP wells can be installed faster • Installation rate two to five times faster than conventional wells • Site characterization can be completed faster

  36. Systematic Project Planning Dynamic Work Strategies Real-time Measurement Technologies Advantage – Work Smarter The Triad Approach • New work strategies like the Triad approach improve • Quality • Cost effectiveness • Time to complete • DP wells integrate well with dynamic work strategies component of Triad Uncertainty Management ITRC Technical and Regulatory Guidance for the Triad Approach (SCM-1) available at www.itrcweb.org under “Guidance Documents” and “Sampling, Characterization, and Monitoring.”

  37. Advantage – More Representative • Representative chemistry and field parameter measurements • Case studies discussed later • Hydraulic conductivity similar to conventional wells • University of Connecticut/ Port Hueneme study • Overall representativeness improved due to greater affordability of DP wells – install more of them

  38. Advantage – Landowner Friendly • Generally smaller drilling equipment • Minimal environmental disturbance • Improved landowner relations • Less time on site

  39. Advantage – Less Costly • Less expensive to install, replace, and abandon • DP wells can be installed at a cost savings ranging from 23% to 65%

  40. Disadvantage – Not Suitable for Some Geologic Conditions • Depth of penetration is controlled by the reactive weight or hammer type • Geologic conditions requiring caution • Large particle size • Cobbles or gravels • Consolidated • Bedrock • Cemented soils • Dense sands

  41. Disadvantage – Regulatory Restrictions • Not accepted for long-term monitoring in most states • Annular space requirement • Filter packs • Sealing • Other requirements

  42. Disadvantage – Well Diameter Limitations • Wells limited to a maximum diameter of 2-inches • This may preclude consideration of DP wells in some situations • May also be a disadvantage if geophysical logging is required

  43. Disadvantage – Cross Contamination Potential • Improperly installed well (DP or conventional) may allow aquifer cross-contamination • During DP well installation • No outer casing • No drilling mud • Completed DP well • DP wells installed with the “exposed screen” method have no annular seal

  44. Limitation – Potential for Higher Turbidity Drive cap • DP wells installed with the “exposed screen” method have no filter pack • No filter pack may result in higher turbidity in fine-grained soil conditions • Properly developed DP wells installed with the “protected screen” method are not subject to this problem Coupling Casing Coupling Screen Wellpoint Source: Ohio EPA Technical Guidance, Feb 05

  45. Evaluating Application of DP Wells • The initial evaluation should consider the following • Do state and local regulations allow use of DP wells? • If not, can a variance be obtained? • Are geologic conditions suitable in the study area at the depths of interest? • Do I need wells greater than 2-inches in diameter?

  46. Questions and Answers

  47. ESTCP Sponsored Study – Background • Environmental Security Technology Certification Program (ESTCP) • DoD environmental programs • $3.9B total in FY04 • $3.0B in compliance and environmental restoration • Direct-push wells – commonly used throughout DoD

  48. Objectives of Direct-push Well Performance Comparison Study • Compare groundwater samples • Analyte concentrations • Address long-term monitoring performance • Five test sites • 13 quarterly sampling events • Compare spatial variability of co-located duplicate • Hollow-stem auger wells • DP wells

  49. DP Well Study Advisory Committee Directed DP Well Study Design • Site selections • Individual and well cluster designs • ½” to 2” DP wells; prepack and no prepack • 2” and 4” conventional hollow-stem auger wells • Well installation methods – static and dynamic force • Geologic cross-section • Test duration for long-term monitoring and seasonal effects • Data QA/QC • Statistical analysis and pertinent comparisons

  50. CRREL Hanscom AFB Dover AFB NFESC(Port Hueneme) Tyndall AFB Demonstration Locations Phase I