Four Levels of Investigation Using Case StudiesPresented at CNY Engineering Expo

Syracuse, New YorkNovember 12, 2012

A savings of $4.62

can be realized for every

$1.00 spent on

Subsurface Utility

Engineering work.

Source: Purdue University, Purdue University Department of Building Construction Management, “Cost Savings On Highway Projects Utilizing Subsurface Utility Engineering.”

As defined by the Federal Highway Administration (FHWA), SUE is

“an engineering process for accurately identifying the quality of subsurface utility information needed for highway plans, and for acquiring and managing that level of information during the developmentof a highway project.”

To present a system of classifying the qualityof existing subsurface utility data.

To identify four levels of subsurface utility investigation.

To decrease the risk by increasing the quality of data.

Level D: Desktop Study

Level C: Traditional Topographic and Utility Survey

Level B: Active, Passive, Geophysical Methods

Level A: Non-destructive Vacuum Excavation

RIS

K

QU

ALITY

A Desktop Study

Ideal for project planning purposes

Typically integrated into conceptual design phase

Insufficient for design

Case Study: Upstate New York Hospital

Traditional Topographic and UtilitySurveying Mapping

Utilize surficialevidence and record mapping to show the location of subsurface utilities

Standard deliverable

Significant risk for the owner, the design professional, and possibly the surveyor

Example: National Retail Facility

ALTA/ASCM Land Title Survey (Level C utilities)

Unknown subsurface AT&T communications line on site

Resulted in change order

Level C may not be “good enough”

Active and passive sensing technologies Traced subsurface utilities incorporated in the topographic and utility mappingSignificantly reduces risk for the owner and the design professional

Radio Frequency (RF)Ground Penetrating Radar (GPR)Electromagnetic Induction (EM)MagnetometryClosed-Circuit TelevisionInfraredAcoustic DevicesActive Millimeter Wave

Useful for tracing knownsubsurface utilities

Operates in both a conductive (clamp on) and inductive (place over utility) mode

Utility must be of a conductive material

Somewhat subjective – inductive mode can “jump” to adjacent utilities

Economical, relatively simple to learn, easily interpretable

Provides approximate utility depths –accuracy ±1-inch per foot

Link to Video Clip collecting GPR data

Detects metallic and non-metallic, natural and man-made subsurface features

Useful for identifying unknown utilities or subsurface structures

Emits high frequency and high amplitude electromagnetic pulses that reflect off underground irregularities

Link to Video Clip of collecting GPR data

Subsurface features are detected by creating a magnetic field using an electric current with a known frequency and magnitude through a sending coil.

The currents spur a secondary current in subsurface conductors that is picked up by a receiving coil.

Changes in the subsurface conductivity can indicate buried features.

Case Study: Electromagnetic Induction

Every material has a unique magnetic property, even those not considered being “magnetic.”

Can use a single sensor to measure the total magnetic field strength.

Can use two (sometimes more) spatially separated sensors to measure the gradient of the magnetic field (the difference between the sensors).

Storm and sanitary pipe inspection

Integration with RF technology to determine pipe alignments

Piping condition

Recommend cleaning piping prior to inspection

Link to Video Clip of collecting GPR data

Identify radiant tubing encased in concrete floor slabs

Moisture inspections, typically used for roofs

Leak detection through changes in temperature of surface soils

Energy audits

Case Study: Turning Stone Casino

What if you could “see through” walls to locate and map utilities?

Ultra-high radio frequency technology

Applications for technology in development

Integrate millimeter wave technology with laser scanning technology for 3-D interior mapping

Waiting to receive images from technology developer

Expose utilities in critical areas utilizing non-destructive methods (air or water), both horizontally and vertically

Incorporated into the topographic and utility survey

Allows for adjustments in design for significant savings during construction

Potentially eliminates risk for the owner, the design professional, and the contractor

Cut to video clip

Question 1. The ASCE’s National Consensus Standard defines four quality levels for subsurface utility location.

What quality level is typically utilized for project development but may not be “good enough”?

Question 1. The ASCE’s National Consensus Standard defines four quality levels for subsurface utility location.

What quality level is typically utilized for project development but may not be “good enough”?

Answer. Level C

Question 2. Which ASCE quality level has the potential to reduce the greatest amount of risk?

Question 2. Which ASCE quality level has the potential to reduce the greatest amount of risk?

Answer. Level A (non-destructive vacuum excavation)

Question 3: Name two active and passive sensing technologies that may be used to identify subsurface utilities.

Question 3: Name two active and passive sensing technologies that may be used to identify subsurface utilities.

Answer. Radio frequency (RF), Ground Penetrating Radar (GPR), Electromagnetic Induction (EM), magnetometry, Infrared (IR), acoustic

Question 4. According to Purdue University, what is the potential savings that may be realized for every dollar spent on subsurface utility investigation?

Question 4. According to Purdue University, what is the potential savings that may be realized for every dollar spent on subsurface utility investigation?

Answer. $4.62

Question 5. What is the primary goal of subsurface utility investigation work?

Question 5. What is the primary goal of subsurface utility investigation work?

Answer. To reduce the risk for everyone involved with the project (owner, design professional, contractors, community)