Download - Bachman Interceptor - Microtunneling
BACHMAN INTERCEPTOR
A SUCCESSFUL 48-INCH
MICROTUNNEL AROUND AN URBAN LAKE
PRESENTERS
� Erick Steitle – DWU Project Manager
� Troy R. Hotchkiss, P.E. – Project Engineer
� Ashok Varma, P.E. – Project Principal
UCTA
NORTH TEXAS CHAPTERMay 19, 2016
INTRODUCTION
GENESIS-HISTORY� Bachman Dam Rehabilitation
� Comprehensive Wastewater Collection System Assessment
� Overlapping Priorities & Infrastructure Renewal Needs
� Schedule
PRESENTATION OVERVIEW
� Project Challenges
� Public Relations Campaign
� Design Considerations, Bidding Constraints
� Third Party Construction Management Services
� Results and Takeaways
UCTA
PROJECT NEEDS
BACHMAN DAM
� Aged Interceptor under right
arm of main dam embankment
� Conventional pipe trench/fill
may contribute to leakage
EXISTING PIPELINE CONDITION
� Age – 50-years
� Materials - RCP
� Deflected, corroded
CAPACITY
� Exist. pipe capacity = 25-mgd
� Forecast 2040 flow = 33-mgd
UCTA
PROJECT CONSTRAINTS
LAND USE
� Bachman Lake and Park
� Bachman Hike/Bike Trails
� Bachman Rec. Center
� Unique “Urban Forest Setting”
EXISTING INFRASTRUCTURE
� FAA Air Traffic Controls
� Existing Overhead Power
� UG Power, Gas, Telecom
� Unknown Private Lines
� Conventional pipe trench/fill
may contribute to leakage
UCTA
PROJECT ISSUES AND CONSTRAINTS
� Right-of-Way
� Stakeholder coordination
� Public impacts
� Hydraulic analysis
� Traffic volume
� Utility conflicts
� Environmental constraints
� Constructability
� Geotechnical
� Permitting
� Long range planning
UCTA
APPROACH TO
COMMUNITY COORDINATION
� Early detection, identification and
prioritization of risks
� Better control and project execution
� Micro tunneling and open cut work
� Proactive public relations strategy
� Coordination with Parks Department
� English and Spanish public notices
� Multiple public meetings
� Coordination with contractor
� Led to minimization of risks
� Opportunities for successful delivery
� Outcome = Success
� Minimal complaints from public
UCTA
GROUND CONDITIONS
STAGED GEOTECHNICAL
INVESTIGATION
� Desktop Study
� Wide-spaced borings
� Borings at shaft locations
� Piezometers and Slug Tests
MIXED FACES
� Soft Rock lower 1,000-LF +/-
� Running Sands/Gravels
majority of alignment
� Clayey Sands / Sandy Clay
pockets suspected
GROUNDWATER
� Next to Lake + Sandy Ground
= HIGH GROUNDWATER
UCTA
DEVELOPMENT OFCONSTRUCTION CONTRACT
� By other than open cut
� Used for road /railroad Crossings
� Very little owner control
� Local = Hand mining
� Business as usual
� Local construction capabilities
� Agency expertise and experience
� Is project big enough for “tunneling”?
AT THE SPEED OF LIGHT UCTA
BIDDING OF MICROTUNNEL CONSTRUCTION
� Provided detailed specifications� Included microtunnel methods
� Provided for tree protection
� Assured protection of public
� Attracted competitive bids� Three bidders
� Bids were close to engineer’s OPCC
� Bids were within DWU’s budget
� Final construction cost was within
budget
Project considered a success UCTA
SPECIAL CONTRACT REQUIREMENTS
� ASCE Standard 36-01 microtunnel guide
� Earth pressure balance microtunneling
� High groundwater impact
� Public safety
� Impact on park and community
� Risks recognized:
“If, in the sole opinion of and at the full risk attributable
to the CONTRACTOR, the work may be safely
accomplished by alternative methods on the same or
better schedule, the CONTACTOR may submit a
request to use alternative tunneling methods.
Requests for alternative construction techniques
prepared in accordance with Section 01640 and
detailing the means and methods of performing the
work will be reviewed by the OWNER on a case-by-
case basis.”
UCTA
SPECIAL CONTRACT REQUIREMENTS
� Tunnel safety considered (S-35)
� ANSI/ASSE A10.16-2009 – Safety
Requirements for Tunnels, Shafts, and
Caissons
� Protection of public considered (S-36)
� ANSI/ASSE A10.34-2001 (R2005) –
PROTECTION of the Public on or Adjacent
to Construction Sites
UCTA
THIRD PARTY
CONSTRUCTION MANAGEMENT
� Submittal review by all parties
� DWU , PARD and FAA, stakeholders
� Limited project issues and risks
� MS One Drive sharing technology
� Instantaneous information sharing
� Planned coordination & communication
� Better decisions
� Verified contractor’s execution of the work
� Contractor oversight
� Better quality assurance and control
� Minimization of risks to the owner
UCTA
PROJECT SUMMARY
• Schedule
– Completed in 586 continuous working days
– Within allotted time as extended
– Acceptance on 3/25/2016
• Budget
– Budget cost = $15,291,612
– Final cost = $15,273,856
• Coordination:– Major effort and continuing focus
• Management
– City involved in design & construction
UCTA
TAKEAWAYS FROM A SUCCESSFUL PROJECT
� Holistic planning
� Alignment study and early Stakeholder buy-in
� Detailed technology evaluation
� Microtunneling solution
� Had to be resolute
� Assumption of appropriate risks
� Use of 3rd party CM
� Focus on community impacts
� Public relations
� Stakeholder coordination
UCTA