City Council Agenda
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Memo to: |
Manteca City Council |
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From: |
Michael Selling, Assistant Director of Engineering/City Engineer |
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Prepared by: |
Elba Mijango, Associate Engineer; Somporn Boonsalat, Deputy Director of Engineering |
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Date: |
May 12, 2026 |
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Subject: |
WQCF Capacity Projects (CIP 23002, 23003, 23004 & 23005) |
Recommendation:
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Adopt a resolution approving Amendment No. 1 to the Agreement for Professional Services with Carollo Engineers, Incorporated (C2024-163) in the amount of $343,163 for a total not-to-exceed amount of $1,334,233; approving Amendment No. 4 to the Agreement for Professional Services with Pacific Advanced Engineering, Incorporated (C2022-156) in the amount of $150,000 for a total not-to-exceed amount of $1,240,200; approving a $2,363,050 increase to the Project Contingency to cover unforeseen issues encountered during construction for a total not-to-exceed amount of $3,613,050; and authorizing the City Manager or designee to take all appropriate actions necessary to carry out the purpose and intent of the resolution.
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Background:
In March 2022, Stantec and Herwit Engineering completed a capacity assessment study (“Study”) for the Water Quality Control Facility (“WQCF”). The Study identified 10 interim improvements needed to optimize the WQCF treatment process.
On October 13, 2022, the City of Manteca (“City”) entered into a Professional Services Agreement C2022-156 (Attachment 6) with Pacific Advanced Civil Engineers, Inc. (“PACE”) to provide design services for 4 of the 10 projects: Replace Internal Mixed Liquor Recycle Pumps (“CIP 23002”), Fix Flow Split to North Plant Aeration Basin (“CIP 23003”), Add New Independent Mixing System to Zone B (“CIP 23004”), and Add Process Aeration Control to Improve Monitoring and Control of Denitrification (“CIP 23005”) (collectively the “Project”)
On June 20, 2023, the City approved Amendment 1 to PACE’s Professional Service Agreement for additional tasks associated with the re-design of the north and south aeration basin systems to increase treatment capacity (Attachment 7).
On February 20, 2024, the City approved Amendment 2 to PACE’s Professional Service Agreement for additional tasks associated with an Arc-Flash assessment of the WQCF’s electrical system (Attachment 8).
On September 3, 2024, the City approved the following for the Project:
- A construction contract to C. Overaa & Company, Incorporated (“Overaa”) in the amount of $11,475,000
- An agreement for professional services with Carollo Engineers, Incorporated (“Carollo”) for construction management and inspection services (“CMIS”) in the amount of $991,070 (Attachment 5)
- A Project contingency of $1,250,000
On May 5, 2025, the City approved Amendment No. 3 to PACE’s Professional Service Agreement for additional tasks associated with engineering support during construction (Attachment 9).
The Project construction commenced in October 2024 and is currently 90% complete. To date, Overaa has been authorized to implement the following changes during construction totaling $1,203,060:
- Addition of a static mixer to the south aeration basin (“SAB”)
- Additon of another opening on the SAB influent channel
- Modifying the SAB interior basin walls to improve flow through each basin
- Adjusting the 24-inch pipeline to avoid underground conflicts
- New programming to allow for remote operation of the aeration blowers
- Additional electrical and instrumentation improvements requested by O&M staff
There is now only $46,940 of the Project contingency remaining.
During the Project start-up and testing the following existing issues were identified:
- Leaks at the south primary effluent launders
- Existing conduits causing foam entrapment
- Secondary clarifier flow distribution preventing passage of foam
- North Influent Pumps need to be upsized
Staff is recommending a $2,363,050 increase to the Project contingency for a total not-to-exceed amount of $3,613,050 to address these remaining issues.
Staff has completed negotiations with Carollo for additional CMIS in the amount of $343,163 and PACE for additional design support in the amount of $150,000. The Project is scheduled to be completed this year.
Fiscal Impact:
Staff recommend Council approve the following:
1. Approve the additional Project contingency in the amount of $2,363,050
2. Approve Amendment No. 1 with Carollo in the amount of $343,163
3. Approve Amendment No. 4 with PACE in the amount of $150,000
There is sufficient funding for the following Capital Improvement Program Projects between the Sewer Operations & Maintenance Fund (Fund 640) and Sewer Improvement Fund (Fund 650).
- CIP 23002 Flow Split Repair North Plant
- CIP 23003 Internal Mixed Liquor Recycle Pump Replacement
- CIP 23004 Process Aeration Control Both Plants
- CIP 23005 Zone B Mixing Both Plants
The Project expenses are as follows:
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Description |
Amount |
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Overaa |
$11,475,000 |
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Project Contingency |
$ 1,250,000 |
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Carollo Agreement |
$ 991,070 |
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PACE Agreement |
$ 1,090,200 |
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Other Project Expenses |
$ 2,800 |
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Additional Project Contingency (this agenda item) |
$ 2,363,050 |
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Carollo Amendment No. 1 (this agenda item) |
$ 343,163 |
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PACE Amendment No. 4 (this agenda item) |
$ 150,000 |
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Total Project Expenses |
$17,665,283 |
The Project funding is as follows:
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Description |
Fund 640 |
Fund 650 |
Amount |
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CIP 23002 |
$1,381,800 |
$1,005,483 |
$ 2,387,283 |
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CIP 23003 |
$4,578,000 |
$1,000,000 |
$ 5,578,000 |
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CIP 23004 |
$2,688,000 |
$1,000,000 |
$ 3,688,000 |
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CIP 23005 |
$5,012,000 |
$1,000,000 |
$ 6,012,000 |
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Total Funding |
$17,665,283 |
Documents Attached:
1. Attachment 1 - Resolution
2. Attachment 2 - Location Map
3. Attachment 3 - Carollo Amendment No. 1 (this agenda item)
4. Attachment 4 - PACE Amendment No. 4 (this agenda item)
5. Attachment 6 - Carollo Original Agreement (C2024-163)
6. Attachment 7 - PACE Original Agreement (C2022-156)
7. Attachment 8 - PACE Amendment No. 1 (C2022-156-A1)
8. Attachment 9 - PACE Amendment No. 2 (C2022-156-A2)
9. Attachment 10 - PACE Amendment No. 3 (C2022-156-A3)