The NGWA Certified Vertical Closed Loop Driller (CVCLD) exam is a voluntary certification test: 75 multiple-choice questions, 2 hours, closed book, with 70% required to pass. Over half the questions (43 of 75) cover Construct the Loop Bore. To qualify you must be at least 20, have 24 consecutive months of loop-well or water-supply-well construction experience, and pass the exam.
What the CVCLD credential actually certifies
The CVCLD is a voluntary NGWA designation for drillers who construct vertical closed-loop wells, earned by passing a written exam, and it is independent from the CWD and CWD/PI credentials.
The National Ground Water Association (NGWA) created the Certified Vertical Closed Loop Driller designation as geothermal technology spread, to recognize drillers who pass a written exam on the knowledge and skills involved in constructing a loop well.
It is an independent designation, not a step within the Certified Well Driller (CWD) or CWD/PI track. If you already hold one of those, you still study this exam's own content.
Keep the credential's scope clear: this is a voluntary industry certification, not a state drilling license. Wherever you work, state and local well-construction rules still govern the actual field work.
Eligibility and application requirements
You must be at least 20 years old, have 24 consecutive months of experience constructing loop wells or conventional water supply wells, pass the exam, and submit the application forms.
The experience requirement is specific: 24 consecutive months constructing loop wells or conventional water supply wells. Loop-well construction and conventional well drilling both count, so water-well drillers moving into geothermal work are not shut out.
The application packet has three parts. A Certification Agreement Form, where you agree to the rules of NGWA's Voluntary Certification Program. A Candidate Reference Form, naming two people who can verify your experience. And a current affidavit, a signed statement that you have not been convicted of civil or criminal legal action arising from professional geothermal activities.
Exam format, passing score, and scheduling
The VCL exam has 75 multiple-choice questions, allows 2 hours, and requires 70% to pass. It is closed book, scheduled through PSI, and costs $125.
NGWA’s page identifies a 75-question multiple-choice exam. PSI’s September 2022 bulletin gives VCL a two-hour limit and a 70 percent minimum passing score.
All NGWA examinations are closed book, and you do not need NGWA approval before sitting the exam. The certification application and eligibility review remain a separate process from the exam sitting itself.
Schedule through PSI and confirm the fee and arrangements shown for your booking.
Sources: Groundwater | NGWA Geothermal driller (CVCLD) certification — NGWA certification page: eligibility, exam information, fees; PSI NGWA candidate information bulletin — Content pages 5-7, dated May 2022; VCL content table
The six tested duty areas and their question counts
Construct the Loop Bore carries 43 of the 75 questions; the other five duty areas split the remaining 32.
The distribution below is from PSI’s September 2022 bulletin. Construct the Loop Bore accounts for 43 of 75 questions. Use that allocation together with your own knowledge gaps to plan revision, while covering every listed area.
| Duty area | Questions |
|---|---|
| Develop Project Plan | 7 |
| Initiate Project Plan | 3 |
| Mobilize for the Site | 10 |
| Construct the Loop Bore | 43 |
| Decommission Wells | 8 |
| Demobilize the Site | 4 |
Sources: PSI NGWA candidate information bulletin — Content pages 5-7, dated May 2022; VCL content table
What the job task analysis tells you to study
The exam is built on a DACUM job task analysis for geothermal loop drilling, and its task names tell you exactly which activities the heavy duty areas cover.
NGWA states that the exam covers the skills and competencies reflected on the geothermal vertical closed loop drilling operations DACUM chart. The DACUM chart is a job task analysis: practitioners map the real duties and tasks of the work, and the exam tests knowledge of those tasks. It is a topic map, not a procedure manual, so it names what you must understand rather than giving you step-by-step instructions.
Within Construct the Loop Bore, the chart's task names are your checklist for the 43-question area. They include drilling the borehole, managing and disposing of drilling fluids and cuttings, collecting and analyzing geologic samples, installing temporary casing where needed, pressure testing the loop assembly both before and after installation, installing the loop assembly, placing grout through a tremie pipe, managing grout subsidence, conducting a flow test with freeze protection and sealing before leaving the site, and documenting the work.
The Decommission Wells area (8 questions) maps to tasks such as locating underground piping, pressure testing and isolating the loop, evacuating and properly disposing of loop fluid, placing decommissioning grout, cutting off and documenting decommissioned pipes, and restoring the site. The remaining areas cover planning, mobilizing, and demobilizing, which include tasks like researching site conditions, obtaining permits, verifying utility locations, and conducting tailgate safety meetings.
One caution when you cross-reference documents: the duty letters on the DACUM chart (A through J) are chart organization, not exam codes. Match topics by duty name, using the blueprint table above as your guide.
Sources: Groundwater | NGWA Geothermal driller (CVCLD) certification — NGWA certification page: eligibility, exam information, fees; PSI NGWA candidate information bulletin — Content pages 5-7, dated May 2022; VCL content table; Geothermal ground source heat pump contractors and operators (DACUM research chart) — Job task analysis, June 2017; duties A-J
One definition worth knowing cold
State exam materials define a closed-loop geothermal well system as continuous piping, partly installed in the subsurface, through which a heat-transfer fluid moves without ever leaving the piping.
North Carolina's well contractor sample questions include a definition that is useful study material for any closed-loop driller. In substance: a closed-loop geothermal well system is a system of continuous piping, part of it installed in the subsurface, through which a fluid moves without exiting the piping, and which is used to transfer heat energy between the subsurface and that fluid.
The defining idea is the intended fluid path: heat transfers between fluid inside the continuous piping and the surrounding subsurface. It does not require discharging that circulating fluid into groundwater.
This is supplementary conceptual background from North Carolina’s published sample material, not a separate NGWA exam requirement.
Practice
A paper diagram shows fluid circulating through a continuous buried pipe loop and returning to the building. The fluid remains in the pipe while heat transfers between it and the surrounding subsurface. Which feature makes this a closed-loop arrangement?
Show answer
The circulating fluid stays within continuous piping; heat is exchanged with the subsurface without discharging that fluid into it.
The supplied diagram matches the definition’s two key features: a continuous fluid circuit partly underground and heat transfer between the fluid and subsurface.
Study materials and a practical preparation sequence
Study from NGWA's listed references, weight your time toward Construct the Loop Bore, and finish with practice questions under time pressure.
NGWA names the study materials for this exam: the Guidelines for the Construction of Loop Wells for Vertical Closed Loop Ground Source Heat Pump Systems, the Lexicon of Groundwater and Water Well System Terms, and Groundwater & Wells, third edition. Additional recommended titles are listed in the certification study materials section of the NGWA bookstore.
One optional sequence, clearly labeled as study advice rather than an official requirement: first, read the DACUM task list and mark every task under Construct the Loop Bore, since that area alone is 57.3% of the exam. Second, work through the loop-well construction guideline against each task name so you can explain what each task involves and why it happens where it does in the sequence. Third, cover the smaller areas, giving Decommission Wells more attention than its size might suggest because abandoned or unfinished boreholes carry environmental consequences. Finally, use practice questions under a clock, and when you miss one, identify which task or duty area the question drew from and reread that part of your source material.
- Confirm you meet the eligibility rules before booking
- Schedule your exam sitting through PSI once your application materials are ready
- Use the free practice questions for this credential to test your recall of the duty-area topics
Sources: Groundwater | NGWA Geothermal driller (CVCLD) certification — NGWA certification page: eligibility, exam information, fees; PSI NGWA candidate information bulletin — Content pages 5-7, dated May 2022; VCL content table; Geothermal ground source heat pump contractors and operators (DACUM research chart) — Job task analysis, June 2017; duties A-J
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