Rehabilitating a 105-inch Interceptor – Innovations and ... · Oakland system • Clearly define...

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

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

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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

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/

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”

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

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

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

• 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

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