Staying Out of the Trench · Why is it Important to Understand the Unique Aspects of Trenchless Construction? 1. Cost –Are we addressing the items that most impact project cost?

Staying Out of the TrenchContract Documents Address Unique

Trenchless Aspects

PRESENTER INTRODUCTION

• Joshua P. Farmer, PE• Corporate Tunneling and Drilling

Technology Leader

• Kyle E. Drumheller, PE, CCM• Trenchless Resident Engineer

Why is it Important to Understand the Unique Aspects of

Trenchless Construction?

1. Cost – Are we addressing the items that most impact project cost?

2. Schedule/Duration – Do we have enough information to reasonably

understand production?

3. Risk – Have we allowed for all appropriate/feasible methods? Have we

eliminated methods with low probability of success?

4. Stakeholder Impacts – Do we understand the true scale of known and

possible impacts to the Public, Traffic, or Environment?

5. Quality Assurance – Have we implemented contract measures and

appropriate scope to ensure construction and the final end product meets

expectations and operational needs?

Unique Aspects of Design and Oversight of Trenchless Construction

Higher Incident of Claims

Greater Production Variability; Production Drives Cost

Greater Importance of Geotech info

Method Constructability/Feasibility

Market Conditions and Equipment Availability

Stakeholder Impacts (Public/Traffic/Environmental)

Measurement and Payment (Front Loaded Costs & Float)

Monitoring

Contractor Qualifications

Construction Inspection and CA

Mitigations for the Potential Negative Impacts of these

Unique Aspects:

Approach

Scalable/Proportionate Risk Management Concepts

Contract

Claim Avoidance Strategies

Scope

Sufficient Information

Expertise in Trenchless Methods involved in the Design

Construction Admin & Inspection

Quality Assurance Program

Inspection Expertise

The Sweet Spot

Co

st

Risk Management

Risk

TransferredRisk is EliminatedScalable Risk

Management

Minimum Total

Project Cost

SECTION 3: ACT

Factors Influencing Cost - Claims

“Tunnel Construction involves the Highest Incident of Litigated and Mediated Differing Conditions Claims than Any Other Sector in Water and Wastewater Construction” • Construction Chart Book, fifth edition

• Differing Conditions Claims• Obstruction Claims• Production Delays• Annular Grout

Labor & Equipment

Rates

Production Rates

MaterialsConstruction

Cost

Cost: What Drives Trenchless Cost?

Production Rates

Project Risk

Cost Variability

Contract Risk

Ground Risk

Project Risk

Ground Conditions

Method Capability

Production Rates

Accurate Estimation of

Construction Cost

Geologic conditions

are as important as

any other factor 42%

Geotechnical Investigation

Ground Risk

Define Ground

Variability

Identify Obstructions

Understand Soil

Behavior

Geological Variability/ Complexity

For comparison:

Dallas Metroplex has 5

major soil/rock strata.

11

1

5

4

3

2

El Paso Metro Area

For comparison:

El Paso area contains…

23 different types of

geological strata groups…

showing the broad range

of subsurface conditions

that can be found when

constructing pipelines in

the area.

12

2

3 4 5

6

10

9

8

7

20

19

18

17

16

15

14

13

12

11

23

22

21

High-Risk Ground ConditionsHighly Variable

Practical Understanding of Soil Behavior

Competent

Rock

Weathered

Rock

Sand Silt Clay

Grain Size

USCS Classification

Typical Approach

FIRM

Example: hard, lean clay

SWELLING

Example: plastic clay

SQUEEZING

Example: soft to medium clay (under load)

BOULDERS

Size: Greater than 12”

COBBLES

Size: 3” – 12” (typical)

RUNNING

Example: dry sand

FLOWING

Example: saturated sand

RAVELING

Example: moist, dense sand


FIRM

Example: hard, lean clay

SWELLING

Example: plastic clay

SQUEEZING

Example: soft to medium clay (under load)

BOULDERS

Size: Greater than 12”

COBBLES

Size: 3” – 12” (typical)

RUNNING

Example: dry sand

FLOWING

Example: saturated sand

RAVELING

Example: moist, dense sand


Typical Approach

Competent Rock

Weathered Rock

Sand Silt Clay

Grain Size

USCS Classification

Competent Rock

Weathered Rock

Sand Silt Clay

Grain Size

USCS Classification

Boulders

Cobbles

Gravel

Running

Cohesive Running

Flowing(Fast Running)

Raveling

Swelling

Squeezing

Soil Behavior

Hazen’s Approach


All geotechnical

investigations

Typical Approach

PDR 30% 60% Finaldesign

Project Timeline

Hazen Approach

Desktop analysis• Geological maps

• Historical data

• < $1,000

Improved project

cost accuracyMinimum

soil borings

90%

Strategic

soil borings

(if needed)

Phasing Geotechnical Investigation

Alternatives to gathering soil borings only

River

River

Horizontal Directional Drill

(1000 ft)

Subsurface

Tool:

Electrical

Resistivity Scan

Subsurface

Tool:

Electrical

Resistivity Scan

Great Miami River

Great Miami River

Top View

Profile View

Force Main

Borings

Subsurface

Tool:

Electrical

Resistivity Scan

Top View

Profile View

Subsurface

Tool:

Electrical

Resistivity Scan

Top View

Profile View

Rerouted Force

Main

Understanding Your Tolerance for Risk

What is Risky Depends on Your… Point of View…

Risk TolerancePrioritization of Goals

Minimize

Impact to

Traffic

Protect Existing

Surface

Structures and

Infrastructure

Maintain

Abbreviated

Schedule

Reduce and

Control Costs

1 2 3 4

Method Feasibility – Starts with CapabilitiesWhat are the most important factors impacting Trenchless Constructability?

Jack & Bore/Auger Boring

(J&B)

Stand Up Time

This Graph shows Rock Mass Stability and the anticipated stand-up time for rock during tunnel excavation. However, for every subsurface condition that has cohesion, there is some stand up time

Dry Sand

Tun

nel

Exc

avat

ion

Sta

nd

up

Tim

e (

hrs

)

10-1 hrs

10-2 hrs

10 hrs

101 hrs

102 hrs

Soil Cohesion/Joint Spacing

Wet Sand

Silt Clay Gravel/Cobbles PWR Rock

UTILITY HAND TUNNELING

Pipe Jacking with Shield & Hand Mining

AUGER BORING

Jack and Bore & Pilot TubeOPEN FACE TBM

ExcavationOpen Face Technologies

Method Selection

Microtunneling(MTBM)

Utility Hand Tunneling

(UHT)


(J&B)

HorizontalDirectional

Drilling(HDD)

Pipe Jacking with Shield

(PJ/S)

PilotTube Auger

Boring Methods(PTAB)

Tunnel Boring Machine

Tunneling(TBM)

Pipe Ramming

(PR)



(UHT)


(J&B)


Drilling(HDD)

Open Cut


Tunneling(TBM)

Pipe Ramming

(PR)

PilotTube Auger


• Selection Criteria

Project Requirements

Site Conditions

Soil Behavior

Construction Risks



(UHT)


(J&B)


Drilling(HDD)


(PJ/S)

PilotTube Auger



Tunneling(TBM)

Pipe Ramming

(PR)



(UHT)


(J&B)


Drilling(HDD)

Open Cut


Tunneling(TBM)

Pipe Ramming

(PR)

PilotTube Auger


Selecting the Right Method

Marsh Ln.220 LF 36”

~ 22 ft. Deep

54”

Project Conditions:

Culverts

Gravity Main

200’+ Segment

Length

Low Clearance Line & Grade Accuracy

Access Issues

Running Sand +

High Groundwater +

Worker Safety



(UHT)


(J&B)


Drilling(HDD)


(PJ/S)

PilotTube Auger



Tunneling(TBM)

Pipe Ramming

(PR)



(UHT)


(J&B)


Drilling(HDD)

Open Cut


Tunneling(TBM)

Pipe Ramming

(PR)

PilotTube Auger


Selecting the Right Method

When you are a hammer…Risk should Influence Final Design

• So why would we ever:

• be prescriptive

• restrict means and methods, or

• limit the bidder pool?

MEASUREMENT AND PAYMENT

Consider Utilizing Additional Milestones with Liquidated Damages

• Project Dependent

• Monitor Float Use

• Accurate Progress Schedule Review

Basis of Payment Coordinate Contract

Concise Requirements

Cost-Loaded Schedule

Schedule of Values


Mobilization and Refurbishment Costs of Tunneling Equipment Higher than Typical Construction

• Refurbishment of TBM to Benefit of Owner

• Implement Contract tools to address cost substantiation


• Must Answer: What is the best way to achieve end goal?

• Critical infrastructure mandates allowable settlement through permitting

• Desired frequency of information collection

• Variety of Available Methods• PK Nail Grid

• Subsurface

• Multi-Point Borehole Extinsometers (MPBX)

Factors Influencing Quality Assurance – Settlement Monitoring

• Tunneling Project in Virginia• Several critical road crossings

• 6 lane divided private roadway

• Specifications Require PK Nail Grid

• Acceptable method of monitoring

• Contractor States Issue with Traffic and Area Construction

• Subsurface Monitors Implemented in lieu of PK Grid

Lessons Learned – Settlement Monitoring

Factors Influencing Quality Assurance – Contractor Qualifications

• Single biggest risk mitigation is QUALIFIED Contractor

• For high risk/exposure projects pre-qualification provides jump start to risk management

Contractor Qualification

• By Specification

• Advantage: Does Not Limit who can Submit a Bid

• Risk: Potential for Bid Protest

• Risk: Does not Allow Unpublicized Vetting

Contractor Prequalification

• By RFP

• Advantage: Advertises Project in Advance

• Advantage: Fully Vet – Financial & Experience

• Risk: Potential for Increased Bid Costs

• Risk: Increased Project Schedule & Design Cost

Contractor Experience can be Critical

Construction ContractContractor Qualifications vs Prequalification

Unclassified

Understand there is still a Limited Reliance on “Soils Info”

It is not a procedure to indemnify the Owner

Guaranteed Bore is in direct conflict with EJCDC

Geotechnical Baseline Report (GBR)

Risks are outlined in detail and borne by the Owner

All deviations to the baseline are paid with predetermined costs

Increased Risk to Owner is expected to be offset by Lower Bid Price

Baseline (Interpretive) Statements in Contract

Ensure there is no difference in interpretation of the range of conditions

No Warranty on Quantity or Location, only condition type

Balance Risk with Contingencies

Contractor’s Don’t Absorb Risk, They Price It!

1. Differences in Expectations of Ground Conditions = Differing Site Conditions Claims

2. If we Accept that the Risk is Monetized

3. How do we Best Handle Soils Information and the Construction Contract?

Construction Contract Managing Soils Information

Example: Obstructions

Definitions• What is an Obstruction?

• Stoppage of Tunneling Progress Procedures

Allowances • Obstruction Removal Standby Time

• Obstruction Removal Shaft

Construction Contract Remedy Clauses & Contingency Allowances

Obstruction Risk Tools

Allowances

Prevent paying for unrealized risk

Estimated Cost

without Risk

Bid Price

Risk Profit

What the Owner Sees

What the Contractor Plans

ProfitContractor Continues to Shed Risk:

Risk

Subcontractors

Work Packages/Subs

Claims Owner/Claims

To Avoid Paying For Unrealized Risks“Contractors Don’t Absorb Risk, They Price It”

To Avoid Paying For Unrealized Risks“Contractors Don’t Absorb Risk, They Price It”

Estimated Cost

without Risk

Bid Price

Risk Profit

What the Owner Sees

What the Contractor Plans

ProfitContractor Continues to Shed Risk:

Risk

Subcontractors

Work Packages/Subs

Claims Owner/Claims

Unrealized RiskUnrealized Risk = Profit

• Lack of Direct Observation• How can I know what I can’t see?

• Intuitive Understanding of Geotech

• Understanding Drive Specifics• Critical Document Packets

• Proactive Claim/Issue Resolution• Phase Specific Reporting• Graphical Tracking Tools• Defined Transitions Between Field Staff

Factors Influencing Quality Assurance – Inspection Philosophy

Lessons Learned – Inspection Philosophy

Proactive Graphical Tracking Tools

Raleigh, NC


Raleigh, NC



Raleigh, NC



Raleigh, NC


Require ALL Critical Submittals Prior to Launch

Work Sequencing

Minimize Risk

LESSONS LEARNED

• Avoid overspending/underspending during design and investigation

• SCALED approach to geotechnical investigation

• Risk strategies appropriate for Owner’s risk tolerance

• Ensure qualified Contractors are performing the Work

• Pre-Qualify when appropriate

CONCLUSIONS

CONCLUSIONS

• Ensure General Conditions are adequate for trenchless construction

• Definitions of Key Terms

• Contingency Allowances

• Work Hours

• Experienced field staff is essential• Proactive inspection

• Geotechnical working knowledge

• Effective issue resolution

Joshua P. Farmer, PE – [email protected]

Kyle E. Drumheller, PE, CCM – [email protected]

QUESTIONS

mailto:[email protected]

mailto:[email protected]

BULLPEN SLIDES

INTRODUCTIONThree Main Categories of Unique Trenchless Characteristics

Cost• Higher Claim Rates

• Increased Production Variability

• Increased Reliance on Geotechnical Investigation

• Permitting

• Allowances

Impacts• Public vs Private

• Environmental

• Traffic

• Duration

• Footprint

• Constructability

• Feasibility

Quality Assurance• Contractor

Qualifications

• Settlement Monitoring

• Inspection Philosophy