CNI Locates GPR Pre-Investigation Checklist
- Confirm Job Hazard Analysis (JHA), form review, or equal site safety review documentation (if applicable).
- Confirm and sign safety plan (if applicable).
- Perform site walk and review project scope, review work area locations. Look for visible service access points such as electrical rooms, communication rooms, fire rooms, manholes, handholes, utility boxes, visible conduits, risers, drops, meters, pedestals, transformers/switches, control valves, etc.
- Review known utilities, discuss possible unknowns, and anticipated critical targets with site contact.
- Review site when finished. Suggest any changes that should be made to the clients work area.
- Utilize job site information, available as-builts, prints/plans, and previously used equipment to locate and mark out underground facilities and unknown anomalies.
- Review of equipment capabilities and potential job-site performance impedances.
- Confirm if GPR data samples will be required for reporting.
- Confirm acceptable on-site markings/type of markings (paint, flags, other).
- Review client deliverable requirements.
CNI Locates Methods of Operations Checklist
- Trace all known utilities as reviewed during the site walk.
- Use EM Locator at visible appurtenances (manholes, valves, meters, etc.).
- Use direct connection method when possible (do not connect directly to potentially live electrical cables).
- Use induction clamp if direct connection is not possible.
- Use induction method if induction clamp and direct connection is not possible.
- After connecting or inducing with the transmitter, use the receiver to complete a full 360 degree sweep around the target line.
- Mark and trace all potential EM fields that are detected. During the sweep, measure mA levels on the receiver in order to assist in correctly identifying the target line.
- Identify the target line by tracing it to the connection point/ termination point or the next feature.
- After tracing and marking any utility, sweep parallel to the utility on both sides in order to check for laterals, t’s, services, unknown utilities, etc.
- Insert traceable rodder or sonde into known sewer, storm, and drain lines (if requested).
- Trace the rodder or sonde using an EM receiver (if applicable).
- Use the EM receiver to attempt to locate any unidentified or known utilities from features using passive modes (Power/Radio).
- Sweep using passive modes parallel to the utility on both sides in order to check for laterals, t’s, services, unknowns, etc.
CNI Locates GPR Quality Assurance Procedures Checklist
- Calibrate the GPR system to the conditions at each site per CNI Locates guidelines.
- Perform several test scans with GPR through the work area to determine the approximate maximum depth of visibility.
- Review the clarity of the scan data. Adjustments in gain, depth range, filters, and other settings may be necessary.
- Use GPR to attempt to locate any unidentified and known utilities.
- Collect scans parallel to any marked utility in order to check for laterals, t’s, services, unknowns, etc.
- Document any known utilities that could not be located (due to visibility or limitations).
- Redundancy strategy, EM used in conjunction with GPR to double check marks. Collect GPR scans across all previously located utilities to confirm locations and approximate depths. Document finding with photos and additional reporting/mapping if required.
- Sweep all areas in a grid with spacing determined by site conditions.
CNI Locates GPR Post Investigation Checklist
- Conduct a recap and review of findings with the site contact.
- Explain findings (where did the technologies work well and where were the results inconclusive due to interference and/or soil conditions)
- Discuss any limitations and possible solutions for them.
- Explain markings and depth assessments.
- Review original scope of work to confirm expectations were met/exceeded.
- Complete all necessary paperwork related to the job site.
CNI Locates Concrete Scanning Pre-Investigation Checklist
- Confirm Job Hazard Analysis (JHA), or equal site safety review documentation (if applicable).
- Confirm and sign site safety plan (if applicable).
- Review and utilize available as-builts, prints/plans, and previous equipment findings.
- Perform site walk/project scope and review scan locations. Note visible electrical rooms, PT ground pockets, visible conduits, etc.
- Ask site contact about slab construction, thickness, age, anticipated targets, etc.
- Request to view slab underneath (if possible).
- Determine whether GPR data samples will be required for reporting.
- Determine type of markings (permanent vs temporary).
- Determine client deliverable requirements.
- Review of equipment capabilities and potential job-site performance impendences.
- Review whether mark out will include depth estimates of target(s).
- Review slab on grade procedures. If the scan area includes a slab on grade area and the post scan work requires trenching, a lower frequency antenna may be used to locate targets in the subsurface material under the slab.
CNI Locates Concrete Scanning Quality Assurance Procedures Checklist
- Calibrate the GPR system to CNI Locates specification guidelines. This calibration may be estimated or have test hole performed to determine the correct dielectric of the concrete.
- Perform several line scans in the scan area to determine a rough understanding of how the structural reinforcement was placed in the concrete and the potential for other targets.
- Note the ability to see the bottom of the concrete slab. If it is not apparent, determine possible reason(s) for it not being seen.
- Review the clarity of the scan data. Adjustments in gain, depth range, filters, and other settings may be necessary.
- Scan and mark targets in the scan area.
- Collect line scan data perpendicular to reinforcement target(s).
- Mark out one line at a time, in one direction at a time.
- Mark a minimum of 3 points per object.
- Draw all lines with a straight edge.
- Use continuations arrows at the end of each line it the item continues out of the scan area.
- Check findings using angled scans, with at least 2 scans at each 45-degree angle.
- Check findings using cross polarized scans. Collect at least 2 scans at each 90-degree angle.
- Check accuracy of all markings by inserting a reference dash at the center of each marking while scanning forward.
- Mark scan boundaries for each location.
- Place CNI Locates Concrete Scanning requirements/limitations sticker in each scan area.
- Use electromagnetic receiver and transmitter to connect to exposed utilities (if possible). Follow CNI Locates electromagnetic guidelines.
- Perform passive sweep of each area with electromagnetic receiver using both power and radio modes.
- Document findings with photos and additional reporting (if required).
CNI Locates Concrete Scanning Post Investigation Checklist
- Conduct a recap and review of findings with the site contact.
- Explain findings (where did the technologies work well and where were the results inconclusive due to interference and/or slab conditions)
- Discuss any limitations and possible solutions for them.
- Explain markings and depth assessments.
- Review original scope of work to confirm expectations were met/exceeded.
- Complete all necessary paperwork related to the job site.
