Subsurface Utility Research Articles

Subsurface Utility Extraction and Characterization: Combining GPR Symmetry and Polarization Attributes

Polarization of the electromagnetic wavefield has significant implications for the acquisition and interpretation of ground-penetrating radar (GPR) data. Based on the geometrical and physical properties of the subsurface scatterer and the physical properties of its surrounding material, strong polarization phenomena might occur. Here, we develop an attribute-based analysis approach to extract and characterize buried utility pipes using two broadside antenna configurations. First, we enhance and extract the utilities by making use of their distinct symmetric nature through the application of a symmetry-enhancing image-processing algorithm known as phase symmetry. Second, we assess the polarization characteristics by calculating two attributes (polarization angle and linearity) using principal component analysis. Combination of attributes derived from these steps into a novel depolarization attribute allows one to efficiently detect and distinguish different utilities present within 3-D GPR data. The performance of our analysis approach is illustrated using synthetic examples and evaluated using field examples (including a dual-configuration 3-D data set) collected across a field site, where detailed ground-truth information is available. Our results demonstrate that the proposed approach allows for a more detailed extraction and combination of utility relevant information compared to approaches relying on single-component data and, thus, eases the interpretation of multicomponent GPR data sets.

Evaluation of subsurface utility engineering for highway projects: Benefit–cost analysis

Accurate location of buried utility infrastructures is a vital issue for utility owners, utility managers and engineers, designers, and contractors that perform new installations, repairs, and maintenance on highway projects. Unreliable information on underground utilities can result in undesirable consequences such as property damage, claims, and other social and environmental problems. Subsurface utility engineering (SUE) is becoming a significant method for reducing the potential for underground utility conflicts at the project planning phase. SUE accurately identifies, characterizes, and maps underground utilities through four quality levels. This study presents a SUE benefit–cost analysis (BCA) to encourage a better understanding of SUE and the use of SUE. Eleven main benefit factors and two cost factors are identified and estimated on twenty-two SUE projects and eight non-SUE projects from Pennsylvania Department of Transportation (PennDOT) districts. In addition, this study reveals the relationship between benefit–cost ratio and complexity levels of buried utilities.

Utility impact rating with subsurface utility engineering in project development

A lack of reliable information regarding the locations of underground utilities can not only result in property damage, construction delays, design changes, claims, injuries, and even deaths but can also cause traffic delays, local business disruptions, environmental problems, and utility service breakdowns in highway projects. The subsurface utility engineering (SUE) is an engineering process designed to reduce the potential of underground utility conflicts at the planning phase. The SUE uses new and existing technologies to identify, characterize, and map accurately the underground utilities with three major activities: designation, location, and data management. In this study, a decision-support tool called the SUE utility impact rating form, which refers to utility complexity at the construction site, has been developed to determine which projects should include SUE and the appropriate levels of SUE investigation to be used. In addition, case studies with benefit–cost ratio have been performed to verify the form.

Implementation of subsurface utility engineering in Ontario: cases and a cost model

This paper investigates a relatively new engineering service that is being introduced in Ontario: subsurface utility engineering (SUE). This service combines civil engineering, surveying, geophysics, and nondestructive excavation for the accurate mapping of underground utilities. This paper presents the results of a one-year study that investigated the use of SUE on large infrastructure projects in Ontario. The study involved performing a detailed cost analysis of nine successful SUE projects, four of which are presented in this paper. Potential cost savings were estimated for each case study and all indicated that SUE has a positive return on investment. In addition, two industry-wide surveys were conducted to investigate the effects of inaccurate utility information on projects. Results indicate that inaccurate utility information has a significant impact on project cost, schedule, and damage to existing utilities. Using the results of the case study analysis and the survey, a generic cost model for SUE was developed that relates project specific characteristics to costs that could be incurred because of inaccurate utility information. This investigation provides valuable insight to the application of a relatively new process in Canada following successful results in the United States.

Numerical characterization of surface heave associated with horizontal directional drilling

This paper presents the implementation of an artificial neural network to predict surface heave resulting from shallow subsurface utility installations conducted with horizontal directional drilling. Data gathered from a full factorial field experimentation examining the effects of drilling techniques is utilized in the network development, with the attempt to understand the relationship between construction techniques and resulting surface heave. The developed model is compared to a multivariate linear regression analysis conducted on the raw data, and a sensitivity analysis utilizing the trained network connection weights is conducted to determine which factor has the greatest effect on surface heave development. Further examination of the behavior of the system is provided through a trend analysis which studied the effect of each drilling factor on the predicted surface heave. The results indicate that a neural network would adequately model the relationship between drilling techniques and the resulting surface heave.

Groundwater remediation in residential areas surrounding BRAC sites

A full-scale iron permeable reactive barrier (PRB), composed of three segments, was constructed down to a depth of approximately 40 feet below ground surface (bgs) in an off-base residential area surrounding the former Kelly Air Force Base (AFB) in San Antonio, Texas. The PRB was designed to remediate trichloroethene (TCE)- and tetrachloroethene (PCE)-contaminated groundwater so the groundwater would meet drinking water standards. The PRB was constructed by azimuth controlled vertical hydraulic fracturing (ACVHF) technology in a residential neighborhood with numerous subsurface and overhead utilities. All sections of the PRB were constructed to the design specifications of approximately 3 inches in thickness from a depth of approximately 20 feet to a total depth of 40 feet bgs. The ACVHF method of construction was chosen due to the existing utilities, the requirement to minimize disturbance to the neighborhood, and the constraints of the worksite (residential two-lane road). This article describes the construction challenges and logistics that had to be managed to satisfy site-specific constraints for installing an in situ PRB within a residential neighborhood as part of the overall site remediation strategy for the former Kelly AFB. © 2005 Wiley Periodicals, Inc.

Interoperability Issues for Underground Utilities

Interoperability issues arise when utility managers want to use both geographical information systems (GIS) and computer-aided design and drafting (CADD) for asset management. During summer 2003, the author evaluated the interoperability of CADD and GIS using a case study of the complex subsurface utility systems at the National Aeronautics and Space Administration’s (NASA) Langley Research Center in Hampton, Virginia. The evaluation included testing the CADD and GIS models and interviewing potential users and developers of the data. The evaluation concluded that the facility’s current approach to using spatial data should be modified with the result that the CADD and GIS are considered an integrated and interoperable system: The GIS supports the spatial analysis and the CADD supports the spatial model. Other issues include the choice of software, the accuracy of the spatial model, and various best management practices for spatial model development from legacy data.

Evaluation of an Emerging Market in Subsurface Utility Engineering

Subsurface utility engineering ~SUE! is a fast growing industry segment in the civil engineering arena. Subsurface utility engineering is gaining credibility as a significant tool to reduce the risk from informational uncertainty associated with underground facilities in a construction project. Subsurface utility engineering can minimize the risk primarily through mapping existing underground utility facilities, utilizing surface geophysical technologies, surveying and data management systems. This paper presents a comprehensive evaluation of SUE to facilitate a better understanding of this emerging industry by the many in the construction domain that are relatively unfamiliar with it. Topics investigated include quality levels in SUE, incorporation of SUE strategy at different stages in the construction project, and cost-benefit analysis of SUE based on 71 actual construction projects where SUE was employed. In addition, the results obtained from questionnaire surveys of State Departments of Transportation ~DOTs! and the SUE industry are analyzed, which reveal the trend of state DOTs in the use of SUE and various aspects of SUE business in private sectors.

Archaeological Survey for the Proposed Seton Home Campus Expansion, City of San Antonio, Bexar County, Texas

During November 2003, the Center for Archaeological Research of The University of Texas at San Antonio conducted an archaeological survey for a proposed 9.3-acre development at the Seton Home property in the City of San Antonio, Bexar County, Texas. The Phase I survey consisted of a 100 percent pedestrian survey and the excavation of 24 shovel tests. A portion of previously recorded site 41BX1570 was investigated with six shovel tests, delimiting the southern boundary of the site. Moderate amounts of burned limestone, burned chert, and lithic debitage comprised the prehistoric artifact assemblage. During current and previous investigations, several modern artifacts were encountered with the prehistoric deposits throughout the vertical column to the terminal excavation depth of 70 centimeters below surface. The presence of these modern artifacts, in concert with evidence of significant historic subsurface disturbance, has provided adequate data to determine this site ineligible for inclusion in the National Register of Historic Places or for listing as a State Archeological Landmark. Under the Scope of Work for the current project, archaeological monitoring of a subsurface utility line is specified. Location of the line is proposed at or near the northern property boundary separating Seton Home and St. Peter-St. Joseph Children’s Home. Site 41BX1570 will be bisected by the utility line, regardless of alternative placement in the general vicinity. The excavation of the utility trench and the monitoring of these excavations will occur during the spring of 2004. The results of this monitoring will be reported within a separate letter report. However, this report is produced to summarize the results of the pedestrian survey and serves to provide for clearance of cultural resources only in the remainder of the project area. It is recommended that construction be allowed to proceed outside of the proposed utility corridor.

A decision tool for the selection of imaging technologies to detect underground infrastructure

Damage to underground infrastructure during construction results in undesirable consequences to contractors, project owners and citizens. These consequences include construction delays, design changes, claims, property damages, service breakdowns, disruption of neighboring business and even injuries and lost lives. Subsurface utility mapping is becoming an essential process to reduce the probability of such damages before construction starts. However, a wide variety of geophysical imaging technologies and different application conditions pose challenges in selecting appropriate imaging technologies for the successful identification of underground utilities. This paper describes a decision tool that was developed to assist in selecting appropriate imaging technologies based on site conditions. The proposed decision tool, named IMAGTECH, utilizes the deterministic parallel selection technique (DPST) as a decision framework to evaluate the input values involved in the decision problem.

Preliminary design of an underground reservoir for pumped storage

The current interest in the potential utilization of subsurface space for the storage of a wide variety of materials is responsive to the increasing pressures of environmental concerns, particularly as it applies to the development of urban or suburban space. These pressures, in conjunction with the continuing development of underground excavation technology, combine to provide a situation within which the concept of subsurface space utilization is becoming increasingly attractive relative to more conventional surface developments. Underground pumped storage is currently an economically viable alternative to the conventional above ground type of facility, and is made increasingly attractive by consideration of the reduced environmental impact, which the underground concept make possible. This paper is intended to provide an introduction to the engineering challenges of underground pumped storage, with particular reference to a limestone mine located some 671 m below the ground surface and having a volume of 9.6 million m3. To this end, the paper presents the numerical modeling and analyses to establish a powerhouse setting that would provide both a structurally stable excavation under the loading conditions imposed by the high-pressure brine, and eliminate the possibility of significant brine inflow to the excavated caverns.

Utilities in Highway Right-of-Way: Data Needs and Modeling

Each year, thousands of new utilities are installed within the rights-of-way (ROWs) of highway facilities nationwide. With the proliferation of utilities within their ROWs, it is becoming increasingly difficult for transportation agencies not only to allow more utilities but also to deliver and manage their own transportation systems in a timely and efficient manner. A geographically referenced prototype model that ties the locations of utility facilities to a state highway network and that associates the positional data with details of utility facility ownership, service or commodity type, infrastructure size, material, and other pertinent characteristics is described. The inventory model can accommodate a variety of utility-related processes within a transportation agency, including utility permits, joint use agreements, and deliverables from subsurface utility engineering contracts. Common sources of utility facility data at a transportation agency are reviewed, and a geographic information system model that represents the locations of utility facilities within the highway ROW is described.

Planning and mapping of subsurface space in Japan

The Subsurface Planning Working Group of the International Tunnelling Association organized a survey of planning and mapping of subsurface space and issued a general report summarizing from various countries in 1999. The contents and volume of the contribution from Japan were significantly reduced for want of space when it was included in the general report. For this reason, we present here the entire contents of the report from Japan for reference, though the volume was unfortunately reduced to half the original report, again for want of space. Japan is predominantly mountainous, and urban areas have developed mostly on alluvial planes at river mouths. Such topographical conditions have activated the development of subsurface spaces in Japan. Various attempts have been made to utilize subsurface spaces, e.g., road and railroad tunnels as part of traffic infrastructures, underground shopping centers, waterworks, sewerage, energy-related urban facilities, such as power-transmission lines, and large underground spaces for energy storage. This trend is expected to continue. The current state of such subsurface space utilization in Japan is summarized here, as well as the legal procedures for such construction, development procedure and database related to underground facilities and geography.

Water masses, nutrient levels and sesonal drift on the outer central Queensland shelf (Great Barrier Reef)

A series of 19 cruises in 19 months in the central zone of the Great Barrier Reef was made in 1980-1 981 to examine the seasonal thermohaline cycles and nutrient distributions. The reefs occupy the outer 60 km of the shelf and the mixing there of Lagoon Water, Coral Sea Surface Water, Shelf-break Water and Subtropical Lower Water is examined using thermohaline data. Current meters and thermistors were moored from mid-1980 to mid-1982 to obtain seasonal drift and subseasonal temperature fluctuations. Subtropical Lower Water upwells through the reef zone to create a year-round thermal contrast between Shelf-break and Lagoon Waters, and vertical density stratification reflects this temperature contrast on the shelf Salinity variations reflect monsoonal rainfall and winter evaporation; rainfall and salinity show an interannual variation. The drifts of bottom water over the outer lagoon and of surface water over the continental slope follow the isobaths poleward. In the reef zone between the lagoon and the shelf break, there is a substantial cross-isobath, onshore flow of bottom water. Surface waters exhibit no significant averaged gradients in phosphate, nitrate, nitrite or oxygen utilization aross the reef zone. Surface chlorophyll concentration is high amongst the reefs. Subsurface chlorophyll levels are similarly high inside the shelf break, and subsurface phosphate, nitrate and oxygen utilization increases markedly, seaward across the reefs, particularly near the shelf break.