standard cut vs. keyhole - apwa home · 2005. 9. 21. · standard dcp stone-base 2 blow/inch...

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KEYHOLE TECHNOLOGY An O&M Infrastructure Management Tool For

the 21st Century

Utility Micro-Surgery

2005 APWA International Public Works Congress and Exposition

Tuesday, 13 September 2005

T. Mark Andraka---- Sr. Engineer

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Standard Cut vs. Keyhole

3’ x 4’

1.5’ x 1.5’

10” or 18”

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Small Hole Encapsulation Work1980- 1990 Vintage

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Infrastructure Installations and Repairs made Safely– Efficiently--

From above the hole

Photo Credit Omega Servac

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Keyhole Opportunities

Reduce Restoring Costs

Coring

Urban Microsurgery2000– Plymouth Twp. Completion of GTI Reducing Excavation And Restoration Project Phase II2001---GTI Keyhole Workshops— Phoenix AZ & Hartford CT 2003–Ongoing---- GTI Keyhole RC Project

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Pipeline & Gas Journal

“New Technologies, Close Coordination Save PECO Energy $1M”August, 2002

Mark AndrakaBrian CamfieldBill HuttonAllen Spivey

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Enhancements to Vac Technology Resulting from

PilotTeamed with SerVac/Omega & GTI

Trailer Vac Unit with Mobile Dump ValveHose Assisted Unit –One Man Soil Breakup and VacuumStorage area for PipehawkAir-Water Knife

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Standard Cut

Standard Cut3’X4’’Excavation

Excavate +/- pipe

In-hole repair process

Temporary black-top

Cut-backs

Separate Re-pave Contractor

Dumping & Transportation Fees

Up to 6 week time frame start to finish

Keyhole10”—18” Excavation No need to excavate below pipeAbove ground repair process

Core reinstated-- No cut backs Homogeneous materials Can be performed year-roundMinimal Impact to Traffic Flow and PublicJob Complete prior to crew leaving site

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Our Challenge

Enhancement and Introduction of New Technologies into Operations

Technologies accepted into work forceThe right technology for the right circumstance

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THE PECO Energy Keyhole Technology Development Project

A SerVac/Omega-GTI-PECO Coordinated Effort2003-2004

Tools & ProcessesExcavationsCore HoleNo Cut-BackOne Day Complete JobMicro-ExcavationLocatingPin-pointingLeaksFacilitiesLess Time to Complete JobLess Customer DisruptionsMore Core Business with LessTrue Two-Person TeamComplete --Start-Finish

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Pavement Coring Machines

6”, 8”, 10” or 18” Cores

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Rotary Cutter for Cores-- Different Depths & Compositions

Thin Asphalt Thick Asphalt

Thick Composite and Reinforced Concrete

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Core ReinstatementBackfill & Compact

Grout Mixture

Core Placement Finished Repair

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Excavation Tools

Air Knife / Air Spade Water Jetter

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Specialized O&M Tools

Extend

ed Ha

ndle

w/Deta

chable

Tools

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PECO Energy O&M Processes

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New and Replacement Services Installed

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Anode and Test Station Installations

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Curb Valve Installations

> Credit collection

> Safety

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… 30 Minutes Later -- Open for Traffic!

Completed repair almost invisible.

No overnight road plating

Restoration is traffic bearing in 30 minutes

No return trips to make final restoration

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What does this mean for the Road? - Improved Pavement

Performance!Size Matters! Keyhole is 80% smaller than conventional utility cut --more aesthetically pleasing with less damage to road systemPrecision core cutting avoids collateral damage to road --no backhoes, jackhammers and over cuts from concrete sawsNo temporary patching.Replaced core exactly matches composition of original roadReinstates road to original weight bearing capacity

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Post Job Process

F(Direction of Traffic Flow)

R

L Core Hole Grout Line

Test Point Holes

CMT

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Cold Weather Process

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Enhancements for MainstreamLocation Location Location

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A SolutionA New Way to Undertake Our Infrastructure O& M

Processes

Inactive Gas Service Cut-offs

Past

Future

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Soil Compaction Measuring Device Study

Presented to APWA 2005 Conference

- Daniel Vetter, P.E.Gas Technology Institute - GTI

Tuesday 13 September 2005


Outline of Presentation

Objectives

Testing Program

Tools

Results & correlations

Conclusions & Recommendations


Objectives ..

Provide the Inter-Agency with an evaluation of the currently available soil compaction measuring devices as an alternative to the Nuclear Density Gauge [NDG].

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Objectives ..

Why replace the NDG?

Operator must be trained and licensed

Company must have EPA approval

Storage, transport and disposal of unit must be monitored


Objectives ..

Why replace the NDG?

EPA initiative to investigate alternative devices

FHWA research plans to develop alternative compaction control devices.


Objectives .. Why replace the NDG?

Not the best device in cuts. Readings near trench walls are affected by sidewall boundaries

“Offsets may be required .. if the material has concrete, some coal, and ferrous soils . . The gauge requires an offset if measurements are taken inside a trench…” Troxler Manual, model 3440

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0

10

20

30

40

50

60

0 5 10 15Distance from side wall (inch)

% I

ncr

ea

se i

n m

ois

ture

co

nte

nt

.

4-inch probe

8-inch probe

12-inch probe

The Nuclear Density Gauge


Sand Backfill0

6

12

18

24

30

36

0 10 20 30

Moisture Content [%]

Keyh

ole

Dep

th (in

ch)

NDG Moisture

Oven Moisture

The Nuclear Density Gauge


Soil Compaction-Measuring Devices

Testing Program

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Determine Backfill Properties

0

10

20

30

40

50

60

70

80

90

100

0.0010.0100.1001.00010.000100.000Sieve Opening (mm)

% Pa

ssin

g

NJ-Sand

IL-Sand

Silty-Clay

Stone-Base


Determine Compaction Properties

ControlBackfill Moisture in all Test layers


In-Process Devices (Q/C)

Soil Compaction Supervisor(SCS)

Utility DCP

GeoGauge

Clegg Hammers

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Post-Compaction Devices (Q/A)

Standard DCP

PANDA Meter


These devices were evaluated with respect to the Control Devices:

Nuclear Density Gauge

Sand-Cone Apparatus

and the Ag. Moisture Gauges


Tests in Bellhole Sections

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Tests inTrench Sections


Tests inKeyhole Sections


Soil Compaction Supervisor (SCS)

Easy–Minimal trainingEase of use-Training

WorkerOperator skill

NoneASTM Standard

FairDurability

GoodPortability

Pre-set SystemCalibration of Device

NoMoisture Readings

Max. Attainable Compaction (Pass/Fail)

Measurement

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Soil Compaction Supervisor (SCS)

GoodOutput Consistency

N/ASurface Readings

Up to 30 inchesDepth of Reading

YesKeyhole Application

No effectTrench Boundary

Stores in memory(needs enhancement)

Data Storage

QC [continuous during compaction]

QC–QA Application


Utility DCP

Easy –Minimal trainingEase of use-Training


NoneASTM Standard

GoodDurability

GoodPortability

NoCalibration of Device

NoMoisture Readings

Penetration (blow count)Measurement


Utility DCP

FairOutput Consistency

Unreliable in top 3 in. in sand

Surface Readings

Up to 8 inchesDepth of Reading

Needs extension rodKeyhole Application


Manual recordingData Storage

QCQC–QA Application

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Utility DCP

11Stone-Base

22 Silty-Clay

4-6Sand

Acceptance Criteria (*)

Soil Type

(*) - Acceptance Criteria is for 90% Modified Relative Compaction

- Previous device calibrations in sand had acceptance criteria of 6


GeoGauge

Easy-Minimal trainingEase of use-Training


ASTM 6758ASTM Standard

GoodDurability

GoodPortability

calibration plateCalibration of Device

NoMoisture Readings

Soil Stiffness & Young’s Modules

Measurement


GeoGauge

FairOutput Consistency

Sensitive to surface stiffnessSurface Readings

9 inches as per manufacturer[not confirmed in tests]

Depth of Reading

NoKeyhole Application

affected by side wallTrench Boundary

Stores DataData Storage


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GeoGauge

No correlationStone-Base

45Silty-Clay

30Sand

Acceptance Criteria (*)

Soil Type

(*) - Acceptance Criteria is for 90% ModifiedRelative Compaction

- Previous studies by FHWA showed acceptance values from 25 to 36 for A-3 and A-4 subgrade.


Clegg Hammers

Easy –Minimal trainingEase of use-Training


ASTM D-5874ASTM Standard

PoorDurability

MediumPortability

Factory calibratedCalibration of Device

NoMoisture Readings

Clegg Impact Value (IV)Measurement


Clegg Hammers

MediumOutput Consistency

Sensitive to surface stiffness

Surface Readings

About 8 inchesDepth of Reading


No effect Trench Boundary

Manual displayData Storage


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Clegg Hammers

914Stone-Base

6 8 Silty-Clay

5 6 Sand

Clegg Hammer20-Kg

Clegg Hammer10-Kg

Soil Type

(*) - Acceptance Criteria is for 90% Modified Relative Compaction.

- Previous studies on device presented a calibration with soil CBR ratio.


Standard DCP

Easy-Require data plottingEase of use-Training


ASTM D-6951ASTM Standard

GoodDurability

MediumPortability

NoCalibration of Device

NoMoisture Readings

Penetration (blow count)Measurement


Standard DCP


Not recommended for top 6 inches in sand

Surface Readings

Full depth (up to 3 ft)Depth of Reading



Manual recording (can be Automatic)

Data Storage

QA [Full depth]QC–QA Application

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Standard DCP

2 blow/inchStone-Base

5 blow/inchSilty-Clay

1.1 blow/inchSand

Acceptance Criteria

Soil Type

(*) - Acceptance Criteria for 90% Modified Relative Compaction

- Previous studies by Mn-DOT in granular base recommended 0.75 inch/blow (1.33 blow/inch)


The Panda

Extensive trainingEase of use-Training

TechnicianOperator skill

(French Standard)ASTM Standard

GoodDurability

MediumPortability

Factory calibratedCalibration of Device

NoMoisture Readings

Tip Resistance & Penetration

Measurement


The Panda


Not recommended for top 6 inches in sand

Surface Readings

Full depth (extension rods)

Depth of Reading



Stores in memoryData Storage

QA [Full depth]QC–QA Application

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Summary

QC devices are the tools needed for layer-by-layer compaction control of restored utility cuts.

The output of the devices provide a measure of soil densification.

The acceptance criteria were determined based on for 90% Modified Compaction at optimum moisture contents.


Acceptance criteria can be achieved bycontrolling the moisture, lift thickness to 6-9 inches, and by using the appropriate compaction tools.

The Utility DCP, the 10-kg Clegg Hammer, and the SCS were the three QC devices that had the best qualities for utility restoration work.

Summary


Recommendations – Utility DCP

Improve drop height and handle design

Add-on drop weight

Storage and downloading capabilities

Easy user interface for location information

Add-on moisture measurement

Handle extension for use in small-hole excavations

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Recommendations – Clegg Hammer

Redesign of guide tube and improve cable connections

Improve movability: Carrying case and cart

Add storage and downloading capabilities


Add-on moisture measurement

Handle extension for small-hole excavations


Recommendations – SCS

Include numerical readout to define acceptance values

Increase sensor depth range

Add button and/or light for new holes

Improve compactor type identification

Modify data storage


Add-on moisture measurement capability


Questions?


standard cut vs. keyhole - apwa home · 2005. 9. 21. · standard dcp stone-base 2 blow/inch...

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