rehabilitating a 105-inch interceptor – innovations and ... · oakland system • clearly define...
TRANSCRIPT
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Rehabilitating a 105-inch Interceptor – Innovations and
Lessons Learned
Pipe User Group | Northern California
March 13, 2018
Tim Karlstrand and Gary Warren
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Agenda
• System Overview
• Project Need
• Video
• Lessons Learned
• Technology Evaluation
• Hydraulic Analysis
• Cost Savings
• Odor Management
• Reducing Community Impacts
• Phase 1 Lessons Learned
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East Bay Municipal Utility District Overview
• EBMUD provides wastewater treatment for 680,000 of its 1.3 million water customers (“west of hills”)
• Wastewater is collected in large diameter interceptors from seven satellite communities – Alameda
– Albany
– Berkeley
– Emeryville
– Oakland
– Piedmont
– Stege Sanitary District
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Wastewater Flow Range
•Wastewater flow from satellites (MGD = million gallons per day)
– Average annual flow = 50 MGD
– Peak wet weather = 415 MGD (at MWWTP)
– Peak wet weather = 700 MGD (system-wide)
– Primary treatment = 320 MGD (max)
– Secondary treatment = 168 MGD (max)
• Significant peaking factor is a key challenge
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Wastewater Interceptor System
• EBMUD
– 29 miles of gravity interceptors
– 8 miles of force mains
– 15 pump stations
– MWWTP, plus 3 WWFs
• Satellites
– ~1,600 miles of regional collection system
– ~1,600 miles of private sewer laterals
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Background Project Need • Corrosion of the South Interceptor is active and
rehabilitation is necessary
– Due to high levels of hydrogen sulfide
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Background Capital Improvement Program
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CIP Update Four Phases of 3rd Street
• Four phases of work over 8+ years
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Project Segment Total Project
Cost 3rd St Rehab Phase 1* $9.0M
3rd St Rehab Phase 2 $24.9M
Special Structures Rehab $8.3M
Embarcadero Rehab $12.8M
Total $55.0M *3rd St Rehab Phase 1 construction estimate is $6.8M
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Video
• California Association of Sanitation Agencies (CASA)
2017 award for Outstanding Capital Project https://casaweb.org/about-us/awards-program/
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Phase 1 – 4 Project Scope
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Phase 1
Phase 2
Phase 4 (Embarcadero)
*Phase 3 not shown (Special Structures)
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Constraint Analysis
• Flow – Dry weather construction
– No pumped bypass (of interceptor flow)
– Tributary flow management
– Daily sediment deposition
• Capacity – Reliability during construction
• Method cannot significantly restrict capacity during non-work hours
– Rehabilitated pipe • New profile cannot significantly reduce capacity
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Lessons Learned Damage Repair Project
• 1993 Danby
• Rigid sheets
• Grouted in place
• No repairs needed
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Lessons Learned Wood St Projects
• 2001 Linabond
• Flexible sheets glued with “structural polymer”
• Many repairs needed due to hydrostatic failures
• 2012-15 Linabond
• Rigid sheets glued with “structural polymer”
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Technology Evaluation Overview
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• 10 methods evaluated, 5 screened as feasible
Alternative Project Installation
Post Construction
Manned Inspection
Repairs To-date
Danby Crown
SD-205A 1993 1997 None
Linabond SD-238 2000 2007
2012*, 2017**
SD-342 2012-15 n/a n/a
Ameron SD-297 1993 2015 None
Hobas Numerous Large
Diameter Numerous Some
Sekisui & Danby Spiral
Waterside Large
Diameter ? ?
* ’12 329 individual repairs, 1567 square feet of repairs. ** ’17 9 repair of repairs
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96-97” diameter
Rehabilitation Systems Slipliner Detail (complete liner)
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97-100” diameter
Rehabilitation Systems Spiral Liner (complete liner)
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Rehabilitation Systems Crown Liner Manufacturer
• Danby specified
• No known equal
• Linabond not be specified
• Higher cost
• Longer schedule
• Quality concerns by Linabond
• Lower life cycle
• Unresolved safety concern
• Ameron Arrow-Lock specified for repairs
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Rehabilitation System Evaluating Alternatives (Operations)
Alternative Operations Impacts*
Remote Plant
1. Crown Lining Medium Medium
2. Slip Lining Low Low
3. Spiral-wound Liner Medium Medium
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Rehabilitation System Evaluating Alternatives (Cost)
Item Alternative
Crown Liner Slip Lining Spiral Liner
Number of Potential Bidders
2 5-10 1
Historic Bid Spread*
40-50% 10-25% n/a
Marketplace Volatility
High Low Medium
*Actual bid range $4.9-7.5M, Engr Est $5.9M
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Platform
Rehabilitation Systems Crown Liner Detail (Ph1 Selected – Danby)
101” diameter
Lower Termination Level
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Flow Management Strategy
Extended Work Hours to Lower Cost and Community Impacts
Weir Wall
• Schematic of In-System Storage
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Flow Management and Working Hours Control Gate Location
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Flow Management and Working Hours Control Gate Layout
• District purchased standard wastewater control gate • District designing the bulkhead wall • Contractor got O&M training • District tested before rehab starts
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South Interceptor Diurnal Water Level
Platform Level Possible Work Hours
• Flow modeling in work area
PS-H Off PS-H On
Flow Management and Working Hours Remote Operations Impacts
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South Interceptor Projected Flow at IPS
Flow Management and Working Hours Plant Operations Impacts
Total Projected Flow at IPS
Projected Storage at Plant ~7 MG
Assumed Plant Base Flow Rate
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Scenario Available
Work Hours Productivity Work Hours
Wood St 4 2
3rd St 10 8
Productivity Improvement -- 300%
Potential Cost Savings -- $0.5-1 million
Potential Schedule Savings -- 1-2 months
• Extended work hours due to control gate
• Cost of control gate assembly ~$100K
Flow Management and Working Hours Comparison to Wood St Work Hours
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Safety and Odor Odor Treatment System – Study Overview
• Feed hypo from SAC Dechlor at 1 to 4 gpm
• Goal is to reduce sulfide loading and release during construction
• Collect liquid and gas sulfide data
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•Grab samples taken at S54 and S60
• Conclusions
– Clear reduction in liquid sulfides with 3 GPM hypo feed
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Avg. Sulfide (mg/L)
Baseline Week 1
Baseline Week 2
1GPM Hypo
3 GPM Hypo
S54 2.3 1.8 1.3 0.2
S60 2.5 2.2 1.9 0.4
Safety and Odor Odor Treatment System – Initial Liquid Results
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Safety and Odor Odor Treatment System – Baseline Gas Results
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Average Value During Work Times
Reduction from Baseline
4AM-4PM ppm Baseline 16.9 0% 1 GPM 13.5 20% 3 GPM 7.1 58%
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• Average during 3 GPM hypo feed -> 58% reduction in H2S
Safety and Odor Odor Treatment System – Initial Gas Results
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• Contractor operates hypo feed system
• Cost Savings: Dosing 3 gpm is $108K versus $325K for odor scrubber
• Contractor provides redundant odor control system in work area
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Safety and Odor Odor Treatment System – Contractor Scope
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Challenges/Risks Community/Business
Risk Initial Risk Level
Mitigations Residual Risk Level
Residential neighborhood construction impacts
(working hours and traffic on narrow streets)
High
• Shift work hours to daytime with control gate
• Add temporary manhole outside residential area (inside Post Office)
• Limit work hours for staging and access in residential area
• Design traffic controls to minimize traffic impacts
Low
Public upset about construction impacts (noise, light, and odor) Medium
• Clearly define contractor requirements for controlling construction impacts to threshold values
• Measure and enforce requirements
Low
Public upset about displaced street parking and towing
Medium
• Provide resident notice about no parking via mailers and changeable message signs
• Secure an alternative parking area for residents, if needed
Low
Impact to Post Office operations caused by traffic disruption High
• Add new manhole outside roadway
• Limit work hours for manholes in the path of travel for freight trucks
• Work closely with Post Office
Low
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Challenges/Risks Safety/Regulatory/Permitting
Risk Initial Risk Level
Mitigations Residual Risk Level
Manned entry into active sewer under confined space conditions with hazardous sewer gases High
• Design an odor treatment system that reduces hazardous sewer gas levels below OSHA limit
• Clearly define safety requirements
• Monitor compliance with safe work practices
Low
Sanitary sewer overflow in tributary system (Oakland) caused by contractor’s operations Medium
• Clearly define requirements to maintain free flowing condition in Oakland system
• Clearly define penalties in special provisions for sanitary sewer overflow in Oakland system
Low
Not receiving obstruction and excavation from City of Oakland on schedule
Medium • Obtain pre-approval of traffic control
plans
• Work closely with City of Oakland Medium
Criminal activity jeopardizes safety of District staff High
• Clearly define site security requirements in special provisions Medium
Worker exposure to toxic rehabilitation materials in a confined space condition High
• Only specify materials that are proven safe in a confined space condition
• Specify requirements for ventilation system
Low
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Challenges/Risks Technical/Quality
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Risk Initial Risk Level
Mitigations Residual Risk Level
Design does not provide flow management strategy that provides enough working hours for proper application
High
• Utilize flow equalization available at Plant and South Interceptor to extend working hours
• Utilize temporary bulkhead wall and control gate to extend working hours
Low
Design does not incorporate lessons learned from previous Wood St. Rehab projects High
• Utilize project team from Wood St. Rehab projects for design submittal review
• Incorporate details from Wood St. Rehab project RFIs and COs into bidding documents
Low
Design does not anticipate challenges associated with managing tributary flows Medium
• Collect best available data on tributary flows (size, peak flow rate, etc)
• Clearly define contractor’s responsibility to convey tributary flows in special provisions
Low
Rehabilitation materials are applied under unsuitable conditions High
• Only specify rehabilitation materials that are proven under active flow condition
• Require manufacturer representative assistance during application
• Apply rigorous quality assurance test procedures
Medium
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Questions