Introduction

The Hanford site is operating under a policy of "Zero Risk" for its engineering and construction practices relative to damaging underground utilities.  Recent utility damages during construction activities created an opportunity for Hanford's A/E Construction Management firm, Kaiser Hanford (KH), to evaluate engineering and construction practices. 

KH retained So-Deep, Inc. as an independent consultant for this purpose, specifically to evaluate KH's current practices of subsurface utility engineering and construction and to recommend enhancements in the current program.  James H. Anspach, P.G., Senior Geophysicist for So-Deep, Inc. visited the Hanford site March 8-15, 1995 for this purpose. 

Interviews were conducted with engineering, surveying, construction, mapping, and Ground Penetrating Radar (GPR) "scan" personnel at various organizational levels.  The majority of these personnel were KH employees.  A few were outside contractor forces.  The conclusions presented herein are drawn solely from information provided during these interviews during the week of March 8-15, 1995.  No other independent or direct evaluations or observations were made of the processes followed by various parties at the Hanford site to manage problems associated with underground utilities. Recommendations are presented throughout the report with the goal of identifying improvements in the ability of KH to reduce risks of utility damages during future activities on the site. Although we believe this report is comprehensive, we do not represent that it contains all means and methods available for handling problems caused by underground utilities.

It is important to note that "zero risk" during construction activities is not achievable. Furthermore, any reduction in current risk will carry associated costs. However, current risks can be reduced significantly. 

Recommendations are based on the proven premise that the quality of utility information directly influences the quality of the project. Case studies from other public and private sector projects show that current project costs may be significantly reduced by shifting some costs from current construction budget "contingencies" (current contingencies are up to 50% of the construction budget) to the design budget in order to obtain better utility data early in the project.  Savings come from reduced contractor bids, change orders, delay claims, existing utility relocations, redesign costs, and other factors.  Management of utility data can reduce future research and field data collection costs.  Finally, improved use of construction techniques may lower radiation exposure times, decrease excavation costs, and increase the ability of future detection for buried utility systems.

Hanford site employees appear to be well aware of the importance of utility damage prevention.  They also appear to be receptive and willing to improve their program.  As such, the existing utility damage prevention program at the Hanford site is already very good.  However, significant enhancements can be achieved.  The sections titled "Good Practices" and "Areas for Improvement" present line item summaries of our investigation's findings.

The mid-section of this report expands upon the line items and makes recommendations for addressing each area for improvement on a case-by-case basis. Costs for improvements are estimated when possible.  The last section of this report outlines a comprehensive plan for utility damage prevention that will foster the development of economic and safety synergies.  This plan should be considered as an alternate to implementing recommendations in a piecemeal fashion.  Although this site is scheduled for partial closure within the next twenty years, there will be significant construction activity taking place until then.  Additionally, this plan will allow for a phased cost effective approach to identifying, documenting, and managing the wealth of data that exists at the Hanford site relative to its underground utility infrastructure.  This data management may become a necessary asset for closure efforts.

Good Practices

      Records are referenced in fairly comprehensible database.

      Some recorded utilities are referenced to three dimensional survey control.

      Utility composite drawings are sometimes prepared during preliminary design.

      GPR data are correlated to recorded information by some designers if a GPR scan is done during design.

      Test holes are sometimes requested by the Construction Division prior to construction.

      GPR is sometimes performed both during design and immediately prior to construction in order to identify utilities emplaced in the interim.

      Excavation permits are almost always required.

      Marking tape is specified for new non-metallic utility emplacement.

      Excavation within 5 feet of known/suspected utility is by hand or air lance.

 Areas for Improvement

       Records are mostly as-designed, not as-built.

      Utility records are not furnished to GPR crews.

      Outside A/Es have little opportunity to find/access utility record database.

      Designer rarely asks input of field GPR crew if discrepancies occur during QA process.

      Designer may not get test hole data for design purposes.

      Utility Composite Drawing is not always available for GPR crews.

      Little effort is made to identify "unknowns" before construction.

      15-20% direct construction costs are attributable to design errors and omissions.

      Not all design proceeds with record information.

      Record research rarely done during construction when not done in design.

      Excavation permit appears to mostly function as a "personal liability reduction" document as opposed to a damage prevention device.

      New utilities/exposed utilities rarely recorded in as-built format.

      Errors on construction plans (as far as existing utilities) may not be    corrected.

      GPR is typically the only surface geophysical method used for utility identification.

      Marking tape is emplaced many times right at utility, rather than closer to ground surface.

      GPR depth data reliability perceived as high by designers, not by constructors.

      No feed-back to GPR crew of excavation of "utility signal" if no utility found (no utility found may occur up to 80% of total markings).

      GPR data obtained during design is primarily used for bidding purposes (amount of hand excavation) rather than design avoidance.

      GPR crew has had no formal training or instruction in GPR theory or usage.

      Utilities marked on the ground surface do not follow accepted color-coding conventions.

      Sketches of previous utility detections by scanning crews are difficult to retrieve.

Current Construction Paths

There are two separate paths that construction may take at the Hanford site.  The first path occurs when a major project undergoes an office design with resultant construction plans developed from this design.  There is usually a significant lead time on these types of projects.  The second path occurs when small or "routine" construction jobs require no formal office design, and are designed by field construction forces.  Lead times for this type of project vary, but are mostly very short notice.  There are varied constructors on site, controlled by Westinghouse, KH, Bechtel/CH2M Hill, and perhaps others.  Field Utility Detection Crews (FUDC) are currently pulled off jobs for "more urgent" jobs on a regular basis due to a lack of information about future construction activity.  Sometimes this will be unavoidable; most times it is avoidable.  Time pressures can cause a breakdown of quality and can certainly create costly inefficiencies.

Recommendation: Establish a central office where information on projects following either construction path can be funneled, as soon as they are known, in order to effectively schedule field utility detection crews. All projects involving construction, regardless of who controls them, should follow this process.  This type of operation would be similar to One-Call Centers that are established throughout the country. The difference would be  that the Center should be notified immediately upon a project being scheduled, rather than just prior to construction.  It is anticipated that this Center's capabilities will be minimal.  Costs:  There are many vendors who supply this service.  We do not recommend any one vendor.  However, Mr. Tom Huff of One-Call Concepts previously submitted a proposal to KH to operate a Center.  Costs for the operation of such a Center may be derived from this proposal.  Mr. Ron Rosencrans (715‑635‑7975), editor of Underground Focus magazine, has broad knowledge in this area.   

Current Design Procedures

Design of a construction project can be in-house (KH), controlled by other site primes (Westinghouse, Bechtel, etc.) or subcontracted to off-site A/Es (out-sourced). One of the first steps in this process is to develop a design plan.  There is an existing form used by KH designers entitled "Engineering Requirements for Final Form of Survey ACAD Files" that transmits information from the KH designer to the KH survey and mapping team.  Designers other than KH may or may not have similar forms.  A portion of this form is dedicated to determining the extent of the effort made during design for field identification of utilities.  Basically, it is up to the designer to establish the quality of utility information he desires during design. In most cases, the KH designer will gather existing utility information from some record sources. However, record sources are varied, and not all designers go to the same level of effort to gather these records.  Some records are referenced in a database that refers the designer to microfiche files retained in a central location.  Other records are retained within individual building locations.  Other records may be retained by past and current A/Es on the site.  Different designers have different opinions on the quality of the existing records.  These records may be "As-designed," or schematic, but are rarely "As-built" even if they are represented as such.  Records may be unavailable for out-sourced projects.

Recommendation:  All records need to be available to all designers, regardless of their company affiliation.  Moreover, it should be required that a competent records search be performed.  Costs: Unknown.  All projects should utilize FUDC in order to take advantage of the benefits of good quality information.  These benefits include designing around existing utilities to avoid utility relocations and distancing construction activity from existing utilities.  Recorded information alone is insufficient for this to happen on a regular basis.  Costs:  To be addressed in subsequent recommendations.  Designers should be made aware of available sources for records, their inherent quality, and the advantages of designing around existing utilities when possible or prudent.  Costs: Minimal educational costs.

Designers may or may not make a utility composite drawing on their design plans.  This utility composite drawing may be solely from records, from records and FUDC, or solely from FUDC.  If a utility composite drawing is made, it may or may not be available to the FUDC at the time of their field work.  The designer may make changes to the field data when discrepancies occur between field data and record data.  The FUDC has little if any input in this process.  The FUDC are never given available utility records for their use during field work.  Ostensively, this is so their work is not prejudiced by other sources of information.  However, the interpretation of field data can be very difficult, and having records available to the FUDC at time of field work can greatly enhance their interpretive abilities.

Recommendation: Supply FUDC with all available recorded data on existing utilities.  This should include previously obtained test hole information. Plot FUDC data on the plans, then correlate records to it in order to address utilities of record that may not have been identified in the field.  Resolve discrepancies with the help of the FUDC when prudent. Costs: Minimal.

Test holes are sometimes dug during the design phase of a project, but most often just prior to construction.  If the designer had this information available to him during the beginning of the final design, he might be able to modify the design slightly to avoid conflicts and unnecessary relocations.  At a minimum, the designer would have necessary data available on depth, material type, condition, size, etc. in order to make prudent and cost effective decisions on relocation design.

Recommendation:  Excavate test holes on all potential design conflicts with utilities after preliminary design but prior to final design.  Place this information on the plans and make this information available to the designer.  Educate the designer on how to best use this information.  Document all information found in the test hole.  Reference applicable data to site survey control.  Emplace construction safeguards, such as color-coded ribbons in the backfill and permanent above ground markers. Costs: Approximately $1000 per test hole in non-hazardous areas/soils.

Current Field Utility Detection and Marking Procedures

Current utility detection methods are limited mostly to Ground Penetrating Radar (GPR) with a 500 MHz antenna.  Occasionally, a 50/60Hz detection device is used to identify power utilities.  Very occasionally, a flux-gate magnetometer is used.  No current KH crew has been formally trained in the theory or use of this equipment, or in other available methods of utility detection.  This equipment is never calibrated.  KH crews mark utility indications on the ground surface with different colors of paint. However, these colors are not in compliance with the American Public Works Association, Utility Locating and Coordinating Council's standardized color codes.  This presents confusion to excavators who are trained in these color codes outside of the Hanford site.   

For designed projects, FUDC data is surveyed to site control and retained on the design plans.  For non-designed projects, sketches by KH FUDC are usually made, but are not easily retrievable for future needs due to an inadequate filing system for this data.  Outside GPR providers do not mark utilities on the ground surface. They take data at grid spacings and interpret this data back at their office.  Their deliverable is a drawing.  This technique is typical for geologic investigations but is inadequate for utility detection purposes, both from a damage prevention and an interpretation standpoint.

GPR data as currently documented includes an estimate of depth.  Many designers rely too much on the accuracy of GPR depth data.  The nature of GPR physics limits GPR's ability to determine accurate depths, especially in a highly heterogeneous environment like the Hanford site.  This environment, which is filled with rounded boulders and cobbles, also causes many false interpretations, since a rounded cobble will appear identical to a rounded utility structure.

Recommendation:  Radiofrequency electromagnetics (extremely low frequency, very low frequency, and low frequency ranges) should be used on every project to augment the existing GPR equipment (Pipehorn, Radiodetection RD400, and Metrotech 9860 are good choices).  Costs:  Approximately $8000 per crew. One additional crew required.  Terrain conductivity, magnetics, and acoustic wave propagation techniques should be available on a project-by-project basis (The Geonics EM-31, Schonstedt GA-52B, and Fuji PL-130 are good choices).  Costs:  Approximately $20,000 per set.  A newly developed 30cm SIR antenna should be added to the existing 500 MHz antenna system.  Costs:  Approximately $4000.  If KH forces are using this equipment, they should receive both classroom and field training in its use.  Costs:  Approximately $10,000 per person.  Develop a test bed and a regular system for equipment calibration.  Costs: Minimal.  Adopt the APWA/ULCC uniform color code for utility markings.  Costs: Minimal.  Develop a better filing system/documentation for FUDC data.  Costs: Minimal.  Require all interpretation to be done on site, with ground markings concurrent with the interpretation.  Costs:  Minimal.  Use test holes to document actual depths to utilities, instead of relying upon GPR or other surface geophysical equipment. Costs:  Included elsewhere.

Usually, project limits are established that are quite narrow.  This results in three problems.  First, an inadequate number of GPR scans are made, which makes data interpretation difficult.  Second, many utility indications are necessarily called "unknowns" and little investigative effort is made to identify them, either in the detection stage or the subsequent excavation stage.  Rarely is there any feedback to the FUDC on what is found during excavation, unless a utility is not indicated and it is damaged. Third, slight alignment/design changes in the office may result in planned excavation or slope stabilization to take place outside of the original project limits.

Recommendation: Expand the initial project limits for utility detection.  Expend the effort to identify "unknown" signals/utilities at time of design, or lacking available time, at least during construction or test hole excavation.  Costs:  One additional person.

Construction Practices

All utilities are required to be hand-dug five feet either side of their position as marked on the ground by either the FUDC or from record information.  This requirement is presented to potential constructors at the pre-bid conference.  Constructors inflate their bids to cover this requirement.  Unfortunately, up to 80% of "utilities" as marked on the ground are not utilities.  FUDC are rarely present during this phase.  Therefore, when no utilities are found, there is no training/learning feedback as to why the signal was interpreted as a utility.  Additionally, if FUDC were present during this test pit stage, and material was discovered early in the test pit process that would account for a utility interpretation (such as a cobble or scrap construction material), the area could be quickly scanned to see if that material was the source of the utility indication.  If so, continued hand excavation would be unnecessary.

Recommendation:  Excavate test holes during the construction phase using non-destructive vacuum excavation techniques, when possible, to lessen this bid item.  The costs of excavating (the same utility as exposed during the design phase) a small hole to expose the utility for safety during construction should be less than the costs incurred and bid by the contractor to excavate a massive ten foot pit.  Costs:  Approximately $300 per test hole.  Have FUDC available during this activity for experience feedback and for re-evaluation of signal interpretation.  Costs:  One additional person with equipment.   If test holes are done during design, this step would be unnecessary during construction. We highly recommend the test holes be provided to designers during the design phase.

When construction proceeds on the basis of a field design, there is rarely an opportunity to correlate the FUDC findings with existing record information for errors or omissions.  Sometimes, the necessity for a project to proceed immediately will preclude this quality assurance check.

Recommendation:  Whenever possible, review field work against available record information before releasing the project for construction activity.  Costs:  One person per three field crews.

Construction activity will expose utilities. These utilities may be shown incorrectly on the design drawings or not shown at all.  There is little effort made to correct information on the design drawings, the existing utility record information, or other sources of erroneous information.

Recommendation:  Document all utilities found during construction to site survey control.  Correct other documents when found in error.  Costs:  One survey crew.

New utilities' construction follows the design plans as closely as possible.  Inevitably, changes are made during construction.  These changes are usually documented on a plan sheet, but may not be changed on the original design document or CADD file.

Recommendation:  As-built all new utilities to site project control.  Total stations/automated data collectors may be more efficient than GPS systems.  Costs: One survey crew with equipment.  Equipment estimate is $50,000.

Non-metallic utilities are proliferating.  A marker tape is usually specified to be emplaced at a point eighteen inches above the actual facility.  This marker tape serves a dual purpose if it is electrically continuous:  it allows future detection from the surface by radiofrequency electromagnetic means, and it alerts the excavator to the presence of the utility by giving prior warning during excavation.  However, this marking tape is frequently cut and not electrically spliced back together, defeating its one purpose.  Also, electrically continuous marking tape is not as efficient a conductor as may be necessary in deep or utility congested environments.

Recommendation:  Replace the electrically continuous tape with less expensive non-conductive marking tape in future construction.  Emplace a #12 insulated wire with the new utility (wrapped loosely around the utility, placed inside the utility, or at least in close proximity to it).  Require future excavators to splice the wire if broken.  When possible, bring the ends of the wire to the surface and affix a label.  Record the presence of the wire and the location of its terminus points in a retrievable location. Costs: Minimal.  Permanent above-ground markers referencing such data as depth, size/type of line, etc. can be placed at ground surface during any new installation or exposure and subsequent backfill of existing installations.  Costs: Minimal.

Backhoe excavation is sometimes a very cost effective method.  Its disadvantages include sheeting/shoring requirements and large volumes of earth moving.  Both of these disadvantages can result in utility damages.  For instance, several past damage reports indicated the cause of damage was cobbles rolling down the sides of an excavation and impacting a fragile pipe.  Also, as more volume is excavated, the probability of an undiscovered utility existing within that volume is higher. Mechanical excavation devices generally generate large forces that can damage utilities.

Recommendation:  Review all construction for the applicability for "Trenchless Technologies." (Dr. Tom Iseley, P.E. at Purdue University is an expert in this technology 317‑274‑8720).  Expose utilities before using trenchless technology.   Utilize non-destructive excavation techniques such as air/vacuum systems for bulk removal of soil when prudent.  This might include utility congested areas or areas around known fragile or "critical" utilities.  The possibilities of robotics to operate these types of systems should be considered in hazardous areas.  Costs for conventionally operated Vacuum excavator fabrication:  $250,000.

 All construction at the Hanford site requires an excavation permit.  This permit allows departments, individuals, and organizations to review the excavation plan prior to its implementation.

Recommendation:  Utilize this tool to serve as a final checklist of utility damage prevention procedures.  Costs:  Minimal.  A critical element of the excavation permit should be certification of "as-built" utility locations by competent registered professionals. Costs:  Covered elsewhere.

Mapping and Data Management

There does not appear to be a central repository for underground utility data at the Hanford site.  Many different storage vehicles seem to exist.  This makes future management of data extremely expensive and inefficient.  This expense and inefficiency will result in higher probabilities for utility damages.  There are many inaccurate sources of information now.  It will only get worse.  Different groups within the Hanford site are trying to develop low-cost but effective data repositories.

Recommendation:  Future utility damage prevention can be greatly enhanced by developing a system to manage data.  The existing CAGIS system and the proposed SIMR system may effectively accomplish this task.  The key requirements for a utility damage prevention system are the following:

      Applicable state or site survey standards.  Typically, the basis for the system should be established or confirmed by GPS technology.

      Ability to delineate project limits,

      Ability to reference data by date,

      Ability to delineate data quality,

      Ability to overlay new construction limits over existing control grid,

      Ability to widely but securely control access to the system.

 Initial Costs:  See KH SIMR Strategic Plan.

 A Comprehensive System for Utility Damage Prevention

The following outlines a comprehensive system for utility damage prevention.  The basis for this system is the application of subsurface utility engineering technologies and data management to construction projects.  Case studies of projects and programs using comprehensive subsurface utility engineering show overall efficiencies in design, reduced construction contingencies, reduced utility relocations, and reduced contractor bid prices. These savings more than offset the costs of implementing such a program.  Attached to this report is a list of subsurface utility engineering references that can produce actual cost savings figures.  Also attached is a list of public domain sources of information regarding subsurface utility engineering.

In order to better understand how subsurface utility engineering works, it is important to first recognize the four quality levels of utility information.

      Quality Level "D" - Existing Records:  Results from review of available records.  Gives overall "feel" for congestion of utilities, but is highly limited in terms of comprehensiveness and accuracy.  For projects where route selection is an option, this Quality Level is useful when combined with cost estimates for utility relocations following applicable "clear zone" and other accommodation policies.

      Quality Level "C" - Surface Visible Feature Survey:  QL "D" information for existing records is augmented using surface visible feature survey and digitizing data into CADD.  The danger here is that much of the data is "digitized fiction."  It is not unusual to find a 15-30% error and omission rate in QL "C" information.

      Quality Level "B" - Designating:  Two-dimensional horizontal mapping.  This information is obtained through surface geophysical methods.  It is highly useful for design basis information for conceptual design, and for proceeding prudently to QL "A".  It should not be used for design basis vertical information, or where exacting horizontal tolerances are expected.

      Quality Level "A" - Locating:  Three-dimensional horizontal and vertical mapping.  This information is obtained through vacuum excavation of test holes at points of conflict.  This is the highest level of accuracy of subsurface utility engineering data.  It provides horizontal and vertical design basis information for engineering, construction, maintenance, remediation, condition assessment, and related efforts.

The important concept to grasp is that whenever utility data is portrayed on plans, in GIS systems, or in CADD systems, the quality level of that utility information should be known. Furthermore, accountability for that information should be clearly identified.

The system envisioned for the Hanford site is subject to change but basically is as follows:

A request for utility information comes into the One-Call Center.  This request could be from a designer or a constructor.  The request is evaluated for time frame response and type of project.  If response is on an emergency basis, a FUDC is dispatched with whatever existing records/utility information as can be provided on short notice.  Excavation on any project should not proceed until the FUDC signs off on the excavation permit.

For Construction (field design) projects, the following procedures are used:

A response time is negotiated with the constructor. A field meeting may be necessary prior to the work.

The FUDC uses appropriate surface geophysical techniques within the project limits.  Utility indications are marked on the ground surface.  A sketch of the utility indications is made. These sketches should be referenced in some manner for future retrieval by FUDC personnel. If time permits, applicable ground markings can be surveyed and retained in the GIS database.

The construction foreman or other applicable person decides on which excavation technique should be used to expose utilities before construction (e.g. hand dig or air/vacuum excavation) and schedules this work with the One-Call Center or performs this work with his own forces.  Utilities are exposed.  On a case by case basis, probably best handled through the excavation permit, exposed utilities should be upgraded to Quality Level "A" through survey to site control and retained in the GIS system.  Newly emplaced utilities are as-built (Quality Level "A") and retained in the GIS system.

For design projects, the following procedures are used:

A meeting is held with the designer to determine project limits, project purpose, etc.

The work load is scheduled between available FUDCs and project assignments are made.

The FUDC uses appropriate surface geophysical techniques within the project limits.  Utility indications are marked on the ground surface.  A sketch of the utility indications is made.  Project limits may need to be field delineated through survey, if sufficient accurate features are not available for reference.

Utility marks and project limits are surveyed to site control.  After plotting, existing records are correlated to the field work and discrepancies resolved in the project database.  Utility data is coded as to its Quality Level.

The designer uses this data to develop the construction footprint as much as possible to avoid utility conflicts.  Where conflicts exist or where more data on existing utilities is desired, the designer requests Quality Level "A" utility information.

Quality Level "A" data is obtained through appropriate excavation techniques.  Discrepancies in the Quality Level "B,C,or D" data are resolved and documented on the plans/database.  This information is supplied to the designer so possible adjustments in design to avoid utility relocations can be made, or so that utility relocation plans can be developed.  Construction safeguards, such as color-coded ribbons and permanent markers are put in place at the time of acquiring the Quality Level "A" data.

Before construction, the available utility information is shared with bidders.  Ideally, such information will be placed directly on the bid documents. 

During construction, utilities are re-exposed for excavation safety purposes using appropriate techniques considering cost and safety.

Any new utilities discovered during construction are investigated by the FUDC as to function and location.  These utilities, if left in place, are upgraded to Quality Level "A and/or B".  If any utilities are relocated, or if new utilities are constructed, their locations will be As-built to Quality Level "A" standards and retained in the GIS database.

All of the above work involved in gathering data and assigning Quality Levels is performed under the direction and seal of a registered professional.

The costs associated with putting a system as outlined above into place are very dependent upon scopes of work and construction workload.  However, it is more than likely that there will be actual cost savings, if project budgets are considered as a whole, rather than broken into discrete design and construction phases.  Additional personnel/equipment costs would be less than the total of each line item because of the varied skills of the personnel.  These personnel would be able to identify utilities, survey the ground markings, operate the vacuum excavation equipment, and survey the exposed utilities.

Summary

The existing utility damage prevention program at Hanford has many good features upon which to build a superior program.  Coordination of all site excavating and cooperation of all involved parties is essential.  Development of a data repository, with Quality Levels of utility information clearly delineated, will greatly reduce future data retrieval costs and increase utility safety.  All available opportunities to upgrade utility quality on an as-needed basis should be taken.  Utility damage prevention starts at the same time any construction is contemplated.  Planning, design and construction activities all play a large role.  Safety and economic benefits accrue more value when comprehensive subsurface utility engineering is applied at appropriate times within a project's schedule.

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