455 W Fir Ave • Clovis, CA 93611 • (559) 449-2700
www.provostandpritchard.com
https://us-partner-integrations.egnyte.com/msoffice/wopi/files/b35a03de-27d2-4aa6-8b70- 9fd024f79cd3/WOPIServiceId_TP_EGNYTE_PLUS/WOPIUserId_131.ppeng.egnyte.com/2026 08 24 Bakersfield WWTP2 Digester Gas System Rehab Project.docx Engineering • Structural • Geostructural • Surveying • Planning • Environmental • GIS • Construction Services • Hydrogeology • Consulting Clovis • Visalia • Bakersfield • Modesto • Los Banos • Chico • Sacramento • Sonora • San Luis Obispo • Boise, ID August 24, 2026
Fernando Montes
City of Bakersfield
6901 McCutcheon Road
Bakersfield, CA 93313
Subject: Engineering for the Bakersfield WWTP2 Digester Gas System Rehabilitation Project, Project No. 26WDWW03 Bakersfield, California
Thank you for the opportunity to submit this proposal to provide engineering services. This proposal discusses our understanding of the project, recommends a scope of services together with associated fees, deliverables and approximate schedules, sets forth our assumptions and discusses other services that may be of interest as the project proceeds.
PROJECT UNDERSTANDING
The existing digester gas system at WWTP No. 2 has reached the end of its useful life and needs to be replaced.
This proposal is for the engineering design required to rehabilitate or replace the following systems:
SULFUR TREATMENT PROCESS
Rehabilitate or replace the existing sulfur treatment process vessels, media, and instruments.
1. The CSI Services Final Inspection Report from January 2026 recommends the following actions:
a. Exterior Coating
i. Spot Repair All Vessels
b. Interior Lining
i. Complete replacement Vessels 5658 and 5659
ii. Spot Repair Vessel 5657
2. We propose to perform the recommended actions, as requested by the RFP, but would like to acknowledge two areas where a rehabilitation approach may be deficient:
a. The Final Inspection Report identifies corrosion pitting in the bottom third of Vessels 5658 and 5659 ranging from 0.250 to 0.3125 inches deep. According to the name plate the tank shell has a total thickness of 0.462 inches resulting in a sound wall thickness at these locations of
0.1495 to 0.212 inches or 32 to 46-percent. We recommend that a structural analysis be completed to verify the remaining wall section is adequate. b. ASCE 7 governs seismic requirements and has undergone several revisions since the sulfur treatment process was constructed. These updates have generally served to increase the design seismic event and it is unlikely that the existing vessels and foundation system can be upgraded to meet the requirements in ASCE 7-22.
3. We are happy to work together with the City to identify the approach that best meets the needs of Plant 2.
DIGESTER GAS BLOWER SYSTEM
Replace the existing digester gas blower system including:
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4. Digester gas blower assembly including blower, motors, drive reducer, and inlet and outlet piping back to the existing manifold.
a. Blowers will maintain the same flow rate and discharge pressure. b. Existing blowers have 30 hp motors.
c. Motors to have individual safety disconnect switches.
5. Digester Gas Blower Power and Control Panels
a. The current power panel in the electrical room has a selector switch for each blower allowing for the following options:
i. Constant Speed
ii. Off
iii. Variable Frequency Drive.
b. This configuration was common practice when VFDs first entered the market to maintain operability in the event of a drive failure. Modern drives are more robust and commonly have an internal bypass to provide the same additional reliability. c. The work will include replacing the existing Schneider Altivar 21 drives with new Schneider Altivar 630 drives, eliminating the existing parallel motor starters and operational mode selector switches. The new 630s will:
i. Be controlled at the VFD control panel
ii. Contain an internal drive bypass feature
iii. Send the following signals back to the SCADA system assuming the existing wiring supports them:
1. Run Status
a. Running
b. Ready
c. Offline
2. Drive Speed
6. Local control panel.
a. Evaluate if it is possible to move the local control panel out of the classified envelope to reduce the enclosure rating from NEMA 7 to NEMA 4X to simplify operation and maintenance b. Local Control Panel will have the following controls on the panel front:
i. Switch – Hand Off Auto
ii. Switch – Lead Blower Selection
iii. Push Button – Reset
iv. Indicator Light – High Pressure Alarm
v. Indicator Light – High Discharge Temperature
vi. Indicator Light – Control On
FLARE MANIFOLD PIPING
Replace the existing flare and the low pressure and high-pressure flare gas manifold piping. Flare control.
7. Flare manifold piping and appurtenances
a. We understand the City has begun purchasing and replacement of many of the individual components of the manifold piping including valves, flame arrestors etc. We proposed drawing in all the equipment as if it is new and coordinate with the City during the 60-percent review meeting to confirm which items will be either:
i. Removed and reinstalled,
ii. Owner furnished, Contractor installed, or
iii. Contractor furnished and installed.
8. Local control panel.
a. Replace existing control panel with a new NEMA 4X enclosure. b. Local Control Panel will have the following controls on the panel front:
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ii. Push Button – Reset
iii. Indicator Light – Pilot TC Monitor Good
iv. Indicator Light – Pilot Fuel On
v. Indicator Light – Pilot Flame On
vi. Indicator Light – Pilot Flame Fail
vii. Indicator Light – Blower On
viii. Indicator Light – Blower Alarm
SCOPE OF SERVICES
TASK SD: SCHEMATIC DESIGN
The following tasks will be completed as part of the schematic design:
a. Request recoating budgetary estimate from coating contractors in the area to perform the work as recommended in the final inspection report.
b. Request budgetary estimate for a replacement treatment system. c. Perform structural analysis on sulfur treatment tank wall thickness and provide recommendations for discussion.
d. Provide a short, sulfur treatment technical memorandum showing relative cost of alternative and results of structural analysis.
e. Attend one (1) in-person/hybrid review meeting to confirm design approach.
SD DELIVERABLES
• Sulfur Treatment Technical Memorandum (PDF format)
• Engineer’s Opinion of Probable Construction Cost (PDF Format) • SD Review Meeting Minutes (PDF Format)
TASK CD: CONSTRUCTION DOCUMENTS
The construction documents task will include the Plans, Specifications, and Engineer’s Opinion of Probable Construction Cost.
GENERAL
G01 Cover, vicinity map and sheet index
G02 Legend and abbreviations
G03 General notes, design criteria, process flow diagram CIVIL
C01 Site Plan
PROCESS
P01 Sulfur Treatment Demolition Plan and Section
P02 Sulfur Treatment Plan and Section
P03 Digester Gas Blower Demolition Plan and Section
P04 Digester Gas Blower Plan and Section
P05 Flare and Gas Piping Demolition Plan and Section
P06 Flare and Gas Piping Plan and Section
PDT01 Process Details 1 of 2
PDT02 Process Details 2 of 2
STRUCTURAL
No structural sheets currently included.
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ELECTRICAL
E01 Electrical Cover Sheet
E02 Electrical Legend, Abbreviations, And Notes
E03 Single Line Diagrams And Load Tabulation
E04 Panel Elevations And Schedules
EDT01 Electrical Details
EDT02 Electrical Details
INSTRUMENTATION
N01 Instrumentation Cover Sheet
N02 Instrumentation Abbreviations And Legends
N03 Instrumentation Abbreviations And Legends
N04 Sulfur Treatment Process and Instrumentation Diagram N04 Digester Gas Blowers Process and Instrumentation Diagram N04 Flare Process and Instrumentation Diagram
NDT01 Instrumentation Details
In addition to the drawings Provost & Pritchard will:
o Prepare preliminary technical specifications in CSI format o Prepare Engineer’s Opinion of Probable Construction Costs (EOPCC) o Submit preliminary (60%) plans, specifications, and estimate (PS&E) In-person/hybrid 60% submittal review meeting with the City o Address draft final review comments
o Prepare bid plans
o Prepare City front-end documents
o Prepare bid technical specifications
o Prepare bid EOPCC
o Submit final plans, specifications and estimate
30% CD DELIVERABLES
• 30% construction documents (PDF format)
• Updated EOPCC (PDF Format)
• 30% review meeting minutes (PDF Format)
60% CD DELIVERABLES
• 60% construction documents (PDF format)
• Updated EOPCC (PDF Format)
• 60% review meeting minutes (PDF Format)
90% CD DELIVERABLES
• 90% construction documents (PDF format)
• Updated EOPCC (PDF Format)
• 90% review meeting minutes (PDF Format)
FINAL CD DELIVERABLES
• Bid set construction documents for approval and bid (PDF Format) • Bid EOPCC (PDF Format)
TASK BSS: BIDDING SUPPORT SERVICES
This task assumes that the City will direct the bid process and review of bids with Provost & Pritchard to provide support as follows:
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BSS DELIVERABLES
• RFI Responses (PDF format)
TASK CSS: CONSTRUCTION SUPPORT SERVICES
This task assumes that the City will oversee day-to-day construction activities and Provost & Pritchard will provide support as follows:
• Attend pre-construction conference.
• Attend weekly progress meetings during construction, assumed 12 meetings. • Attend site visit for substantial completion and final walk-through. • Assist in Submittal review and response, assumed 15 submittals • Assist in RFI response, assumed 15 responses
CSS DELIVERABLES
• Submittal and RFI Responses (PDF format)
PROFESSIONAL FEES
Provost & Pritchard Consulting Group will perform the services in this Phase on a time and materials basis, in accordance with our Standard Fee Schedule in effect at the time services are rendered. These fees will be invoiced monthly as they are accrued, and our total fees, including reimbursable expenses, will not exceed our Total Estimated Fee without additional authorization.
PROPOSED FEE
TASK TYPE ESTIMATED FEE
Task SD: Schematic Design T&M $22,000
Task CD: Construction Docs T&M $158,000
Task BSS: Bid Support Services T&M $16,000
Task CSS: Construction Support Services T&M $50,000
Total Estimated Fee: $246,000
The line items shown above are estimates and are not intended to limit billings for any given Phase. Required Phase effort may vary up or down from the line-item estimates shown, however total billings will not exceed the Total shown without additional authorization. If the scope changes materially from that described above, as a result of any agency’s decision or because of design changes requested by the Owner or Engineer, we will prepare a revised estimate of our fees for your approval before we proceed.
SCHEDULE
The City has requested that the design work be completed by March 31, 2027. We have reviewed the scope and have no concerns related to completing the project as requested.
ASSUMPTIONS
1. The City will pay any fees associated with permitting, environmental documents, checking and inspection, and all other fees, permits, title company charges, and all other similar charges not specifically covered by the terms of this agreement.
2. The City will provide:
Record drawings
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3. Provost & Pritchard current CAD version, standards, and title block will be used for the design of this project.
4. The work is purely mechanical and electrical replacement and does include increasing the size, flow, volume of any of the existing processes and as a result does not include any of the following services:
a. Site survey.
i. Project drawings will be based on record drawings and site photos. b. Flow evaluations
i. New blowers and flare equipment will match design conditions for original equipment.
c. Structural
i. New equipment or pipe supports will be included as needed but do not require structural design calculations.
d. Electrical, Instrumentation, and Communication
i. New conduits and conductors will be run from the new field equipment to its respective local control panels.
ii. New wiring will be run from the blower local control panel to the new VFDs. iii. No new signal wiring will be run from the local control panels back to the PLC. iv. The project only includes SCADA improvements for the existing PLC input and output signals.
TERMS AND CONDITIONS
In order to convey a clear understanding of our mutual responsibilities under this proposal, please provide an Agreement for our review and execution. This proposal is valid for 30 days from the date above.
Provost & Pritchard Consulting Group
Brandon Stipe, RCE 75956 Keith Mortensen, RCE 75865
Principal Engineer Director of Operations
TERMS AND CONDITIONS ACCEPTED
By City of Bakersfield
Signature
Printed Name
Title Date
Brandon Stipe, RCE 75956 Keith Mortensen, RCE 75865