page 1 nts perspective on excavation/penetration vision – service - partnership introduction...

NTS Perspective on Excavation/Penetration

Vision – Service - Partnership

Introduction

• Several months ago and again in recent weeks Ambassador Linton Brooks, NNSA has expressed a Zero Tolerance for unplanned electrical events and specifically those involving striking energized underground utility installations during excavation/penetration activities.

• The Nevada Test Site developed a Zero Tolerance approach to unplanned events relative to excavation/surface penetration (E/P) activities several years ago and continue to enhance the process. This discussion is designed to share what efforts work and do not work relative to mitigating the hazards to personnel and equipment during excavation/or penetration work.



Topics

• Background

• What doesn’t work

• Compensatory Measures

• Mitigating the hazards

• Non-Permit Required E/P Activities (safe work practices)

• Permit Authorities

• Compliance with OSHA Standard

• Non-intrusive survey equipment, use and limitations

• Opportunities for improvement



Excavation/Surface Penetrations

• Background

– Less than adequate performance at NTS in 2004

– Six Excavation/Penetration (E/P) incidents in a two month period

– Task team formed to develop path forward

– Improved performance until Sept 2006

– NTS surface grading incident Sept 2006

– NNSA electrical incidents with emphasis on incidents involving striking energized utilities



DOE Complex ORPS Review2004 – 2006 CYTD

• 199 Excavation Reportable Incidents

• 86 Penetration Reportable Incidents

• 7 Excavation/Penetration Reportable Incidents

• Causal Factors– Electrical wiring or utility lines not well marked or accurately reflected on

site maps and drawings

– Inadequate as-builts a major causal factor

– Failure to use locating equipment

– Procedural non-compliance



What Does Not Work



Saw Cut Concrete Floor Incident

110 Volt Stub Up

3.5 inch saw cut

Reviewed wrong drawing and walk down failed to observe the electrical stub up



U1A Surface Laid Cable Incident

480 Volt SLC

Non-Qualified employee moved cable causing arching and loss of power



U1A Surface Laid Cable

SLC connections to trailer



Shoshone Peak SLC

SLC dives under

surface and reappears at

panel



Area 5 Environmental Cleanup Incident

4.5 feet below Grade Abandoned Utility Line



Area 5 Sketch of Identified Utilities



Surface Grading Incident Sept 2006

Substation

208 volt electrical installed >30 years ago at a depth of 3.5 inches



Surface Grading Incident

208 Volts encountered at 3.5 inches below grade

Surface grader severed energized line and tripped 2 breakers in the fleet maintenance building



2004 Compensatory Measures

• Close scrutiny review of all E/P activities for 6 months pending implementation of corrective actions

• Elevated permit signature authority up to the Assistant General Manager

• Established accountability via permitting authorities

• Defined E/P safe work practices

• Implemented new safety rule & trained personnel

• Audited the process improvements for effectiveness



Mitigating the Hazards



Area 23 Fire Storage Tent Electrical Tie-in

Field marking and CAD mapping

Non-intrusive survey using GPR and Metrotech

Hand digging and vacuuming

24 inch deep electrical utility installation



Work Planning Considerations

• Determine methods before work. Use conservative approach.

• Use a registered professional engineer when designing excavations greater than 20 feet in depth.

• LOTO, Confined Space and Radiological Requirements must be considered.

• Prohibit excavations or surface penetrations in areas known or suspected to be contaminated with explosives, unexploded munitions, or military ordnance.



Non‑Permit Required Excavation/Penetration Activities

Exercise Caution When Using These Safe Work Practices• Hanging pictures, boards, etc.,.

• In “green field” or undeveloped areas

• In the middle bottom portion of masonry block (concrete masonry unit [CMU]

• In masonry block walls not to exceed 3/4 inch to 1 inch in depth to facilitate sign mounting and other attachments to these structures.

• In shotcrete or similar underground control applications In underground mining operations in undisturbed material or gravel surfaces.

• Maintenance to, or replacement of (when in the same location), fully or partially embedded/exposed posts



Non-Permitted Required E/P Activities (Cont)

• Penetration in concrete slabs/pads, curbs, gutters and sidewalks that does not exceed 3 inches in depth.

• In pre‑cast tilt‑up concrete walls to mount signs and facility accessories.

• Penetration in drywall, sheetrock, or similar construction material where the drill bit, or equivalent, is fitted with a device to prevent full penetration.

• Penetration in drywall, sheetrock, or similar construction material with a utility knife, or equivalent.



Non-Permitted Required E/P Activities (Cont)

• Penetration in drywall, sheetrock, or similar construction material with a blunt, non-conductive object.

• Use of laminate trimmers with cutting bits adjusted to prevent full penetration in drywall or similar construction materials to facilitate removal of large sections.

• Penetration in new construction activities where process knowledge and/or construction drawings confirm the absence of utilities.

• Penetration on building surfaces where the wall, ceiling, or floor openings can be fully observed and all potential utilities or other obstructions are indisputably visible or marked on the penetration zone.



E/P Evaluation Activities

• Walk down and visual examination of the area.

• Review of design drawings and sketches that are available from the Design Engineering Department.

• Review of as‑built drawings that are available from the Archives and Records Center.

• Contact with external telecommunications companies for telecommunication utilities that might be installed in the area of the planned work.

• Contact with “USA North” local (also known as “Call Before You Dig”), when performing excavation or penetration activities offsite.

• Conduct survey with utility locating instruments

• Do not rely on drawing as a sole source for utility locating.



Permit Authorities

• Designated by Department Manager

• Designate the PA for excavation/penetration activities.

• Maintain a roster of the names or positions that are assigned these responsibilities.

• Not delegate responsibility without approval of the Department Manager.

• Put the delegation in writing using the standardized memorandum.

• Enforce the requirements



Excavation/Penetration Roles & Responsibilities (R2)

• The Permitting Authority (PA) coordinates E/P activities with organizations

– Utilities - Water

– Utilities - Power

– Facilities Maintenance (sanitary sewer, storm drains)

– Natural Gas

– Telecommunications

– Radiological Control

– Safety and Industrial Hygiene (for beryllium, asbestos, and lead)

– Environmental Services



Excavation/Penetration R2 (Cont)

• Requests that the applicable organization(s) field mark the location of the hazards.

• Marks the “Excavation‑Penetration Permit, to show which organizations were coordinated with.

• Require the appropriate non‑intrusive examinations be performed to identify any additional possible hazards. These activities are performed during the discovery process and during the initial walk down.



Excavations Within 5 feet of Utility

• Take the following actions after all underground utilities that are within a 5’ radius of the excavation are “energy safe.”

– Hand dig (with shovels and/or air knifes) using pot holing techniques when within 3 feet laterally or vertically of identified location.

– Once identified, continue the excavation with hand digging to further expose the utility as necessary. If this activity is being conducted under an “Electrical Energized Work Permit,” then the permit will include the following controls:

– No person is allowed to come into contact with the mechanical equipment while excavating other than the equipment operator.

– The operator remains in the equipment at all times while the excavation device (e.g., bucket) is in contact with the below‑grade material.

– The operator removes the excavator device from the excavation and places the device on the surface away from excavation before egress from the equipment.

– Use appropriate personal protective equipment that is consistent with the underground energy source.



Excavations Within 5 feet of Utility (cont)

• Take one of the following actions if it is found that any underground utilities that are within a 5’ radius of the excavation contain hazardous energy:

– Render the utilities “energy safe” before starting work.

– Ensure that asbestos‑containing Transite® pipe materials are not disturbed.

– Ensure that underground installations are protected, supported, or removed as necessary to safeguard employees.

– Suspend work if changes or additions to the utility system are discovered during excavation. Work is not restarted until the changes or additions are addressed in the work package and the “Excavation‑Penetration Permit.”



Excavations Within 5 feet of Utility (cont)

• Where utility markings are within 5 feet or proposed excavation/boring, the utility shall be pot holed.

• Non-Destructive means of excavation are used when in doubt of depth or location of buried object. Vacuuming, hand digging, etc.



OSHA Compliance Standard

• 29 CFR 1926.650 – Excavations. “ Underground installations. (1) The estimated location of utility installations such as sewer, telephone, fuel, electric, water lines, etc, that reasonably may be expected to be encountered during excavation work, shall be determined prior to opening an excavation.” (2) When excavation operations approach the estimated location, the exact location of the installation shall be determined by safe and acceptable means.

• 29 CFR 1926.417 – Subpart K (Safety Related Work Practices) General Requirements. Protection of Employees. No Employer shall permit employee to work in such proximity to electric power circuit unless the employee is protected from electric shock.

• 29 CFR 1910.335- Safeguards for Personnel Protection. (a) Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment.



Other Guidance Documents

• ANSI Standard A10.12-1998 (R2005)

• Compliance is voluntary

• Standard duplicates underground installations language stated in 29 CFR 1926.



Non-Intrusive Survey

• Performing non‑intrusive examinations.

– Ensure that equipment used for non‑intrusive examinations is properly calibrated and used per the manufacturer’s instructions.

– Be trained in the use and know limitations of the non‑intrusive examination equipment.

– Implement the protective measures identified by the PA on the “Excavation‑Penetration Permit.”

– Non-intrusive instruments estimate location, exact locations determined by potholing



Non-Intrusive Examination Methods

Method

Type of Material

LocatableType of Material Not

LocatableEffective Locating

Depth Depth EstimationSoil or Backfill

EffectsDiscrimination

Multiple Materials

Ground Penetrating Radar

Metallic, Plastic, Concrete

Effectiveness depends on size versus depth

Metal: 1” (2.54 cm) diameter for each footdepth; 6” (15.24 cm) diameter for each foot over 12ft. (3.65 m)

Yes.Variable; depends on soil homogeneity

Yes.Wet sandy soils best; saturated clay soils limit depth penetration

Very good discrimination of multiple targets

EM-61 Metal Detector

Metallic or pipes with metallic reinforcement

Nonmetallic 3’ (7.62 cm) diameter pipe at 6.5ft. (1.95 m) depth; up to 12ft. (3.6 m) for large diameter pipes

Yes.Accuracy +15% under ideal conditions

None unless backfill contains metallic debris

Poor discrimination of multiple targets

Metrotech 810 RF (83 kHz) Conductive and Inductive Tracing

Copper: excellentAluminum: very goodSteel: goodCast Iron: poorConductive better than inductive

Nonconductive Inductive: 10ft. (3.04 m) under ideal conditionsConductive: 10 ft. (3.04 m) under ideal conditionsLocation depth affected by conductor and soil type

Yes.Accuracy +10% under ideal conditions to depths of 3 ft. (.91 m)

Yes.Moisture compact soils best; poor tracing in dry sandy soils or alkaline iron content soils

Good discrimination of multiple targets in conductive mode

Metrotech 50/60 Hz Locator

Underground power lines/E&I cables

Pipes without flowing electric current

10mA current at 3 ft. (.91 m) depth for 50% meter deflections; 6 ft. (1.82 m) maximum effective locating depth

None Yes.Same as Metrotech 810

Poor discrimination; affected by nearby conductors and most nearby metal structures



Non-Intrusive Instruments



As-built Comparisons



Non-Intrusive Surveying



3-D Image Data



Pipe Image



Alaska Pipeline



Opportunities for Improvement

• Perform work safely

• Improve reliably of confirmation of presence or absence of utilities

• Upgrade utility location survey instrumentation

• Establish training and task qualification program

• Incorporate use of mock-ups to improve proficiency

page 1 nts perspective on excavation/penetration vision – service - partnership introduction...

Documents

nts perspective

nts surface grading

panel slide

loss of power slide

abandoned utility line

nnsa electrical incidents

excavationor penetration

electrical stub