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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
2
Agenda
• System Overview
• Project Need
• Video
• Lessons Learned
• Technology Evaluation
• Hydraulic Analysis
• Cost Savings
• Odor Management
• Reducing Community Impacts
• Phase 1 Lessons Learned
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
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
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
6
Background Project Need • Corrosion of the South Interceptor is active and
rehabilitation is necessary
– Due to high levels of hydrogen sulfide
7
Background Capital Improvement Program
CIP Update Four Phases of 3rd Street
• Four phases of work over 8+ years
8
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
9
Video
• California Association of Sanitation Agencies (CASA)
2017 award for Outstanding Capital Project https://casaweb.org/about-us/awards-program/
Phase 1 – 4 Project Scope
10
Phase 1
Phase 2
Phase 4 (Embarcadero)
*Phase 3 not shown (Special Structures)
11
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
12
Lessons Learned Damage Repair Project
• 1993 Danby
• Rigid sheets
• Grouted in place
• No repairs needed
13
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”
Technology Evaluation Overview
14
• 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
15
96-97” diameter
Rehabilitation Systems Slipliner Detail (complete liner)
16
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
18
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
19
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
20
Platform
Rehabilitation Systems Crown Liner Detail (Ph1 Selected – Danby)
101” diameter
Lower Termination Level
21
Flow Management Strategy
Extended Work Hours to Lower Cost and Community Impacts
Weir Wall
• Schematic of In-System Storage
22
Flow Management and Working Hours Control Gate Location
23
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
24
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
25
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
26
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
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
27
•Grab samples taken at S54 and S60
• Conclusions
– Clear reduction in liquid sulfides with 3 GPM hypo feed
28
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
29
Safety and Odor Odor Treatment System – Baseline Gas Results
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%
30
• Average during 3 GPM hypo feed -> 58% reduction in H2S
Safety and Odor Odor Treatment System – Initial Gas Results
• 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
31
Safety and Odor Odor Treatment System – Contractor Scope
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
32
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
33
Challenges/Risks Technical/Quality
34
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
35
Questions