TO:Andrew P. Powers, City Manager
FROM:Nader Heydari, Public Works Director
DATE:May 12, 2026
SUBJECT: Hill Canyon Treatment Plant Biosolids Conveying and Storage Improvements Project (CI 5683)
RECOMMENDATION:
1. Approve First Amendment to Professional Services Agreement (Contract No. 14088-2025) with HDR Engineering, Inc. (Ventura, CA), for additional design plans and specifications for the Hill Canyon Treatment Plant Biosolids Conveying and Storage Improvements Project (CI 5683), in an amount of $442,700, plus extra services of $44,270, for a total not-to-exceed amount of $592,350, including previously authorized extra services of $9,580, and extending the term to June 30, 2027.
2. Authorize expense in the amount of $486,970 ($442,700 agreement, plus extra services of $44,270) from A/C #624-8250-682-8300 (Wastewater Fund – Capital Improvements, CI 5683).
3. Find that this action is not a project as defined under the California Environmental Quality Act.
LEVINE ACT ITEM: Yes
FINANCIAL IMPACT:
No Additional Funding Requested. $500,000 is included in the Adopted FY 2025-26 Wastewater Fund Capital Budget, with $898,895 in carryover budget for a total budget of $1,398,895. The total estimated cost of the overall project is estimated at $8,000,000, with this Phase 1 portion being $3,500,000. Additional funding for Phase 1, as well as future phases of the project will be requested as part of the upcoming biennial budget process, and at the time of construction contract award, depending on the bids received.
HCTP Biosolids Conveying and Storage Improvements Project (CI 5683) May 12, 2026
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BACKGROUND:
The Hill Canyon Treatment Plant (HCTP) operates 24 hours a day, seven days a week, providing tertiary-level wastewater treatment for the Thousand Oaks community. On average, the facility treats eight million gallons of wastewater daily through a comprehensive process that includes screening, grit removal, primary and secondary clarification, aeration with nutrient removal, multi-media filtration, and disinfection. The resulting high-quality effluent is beneficially reused for agricultural irrigation and landscape watering.
As part of the wastewater treatment process, biosolids are generated and must be processed and removed from the facility (Attachment #1). The dewatered biosolids are transported off-site for composting and beneficial reuse. Currently, biosolids are dewatered at HCTP using specialized equipment and conveyed via a single conveyor system to a storage hopper for loading into trucks or trailers. Depending on operational needs and seasonal conditions, the material is either transported directly off-site or placed in drying beds for additional dewatering prior to hauling.
This process occurs continuously to support plant operations.
The existing biosolids conveyance system, which transports material from the screw presses to the storage hopper, is over 20 years old and represents a single point of failure. In addition, the current hopper is undersized for existing biosolids production, requiring staff to make manual adjustments during truck loading operations and limiting overall efficiency.
The proposed project will improve system reliability and operational efficiency by adding a redundant conveyance system from the Dewatering Building, installing a larger storage hopper capable of accommodating a full truckload, and providing direct conveyance to the drying beds. These improvements will allow truck loading operations to be reserved for off-site hauling during periods when drying beds are not available, such as during the wet season. The project is intended to enhance redundancy, improve automation, and increase biosolids handling capacity to support continuous 24/7 operations. By reducing the need for manual intervention and continuous monitoring, these improvements will allow staff to focus on higher priority plant operations.
On September 9, 2025, City Council approved a Professional Services Agreement with HDR Engineering, Inc. (HDR), in the amount of $95,800 for preparation of a condition assessment and a preliminary design report (PDR). The PDR was the first part of a larger overall scope of design and engineering work that was included in the Request for Proposals (RFP). HDR completed the PDR in February 2026.
HCTP Biosolids Conveying and Storage Improvements Project (CI 5683) May 12, 2026
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DISCUSSION/ANALYSIS:
The PDR was completed using a thorough evaluation of the existing biosolids handling system and comparison with industry standards and similar facilities. The PDR further identified the need to expand the project scope to address operational limitations and system deficiencies. The full proposed expanded project scope of the project is estimated at $8,000,000, and includes the addition of redundant screw conveyors, a larger storage hopper, and improvements to the truck loading and scale alignment system to support more efficient and reliable operations.
These enhancements address the existing single point of failure, operational inefficiencies, and limited storage capacity necessary to improve system reliability, support continuous 24/7 operations, and reduce the need for manual intervention.
Due to the increased costs, the project will be split into three phases:
Phase 1 – installation of a redundant screw conveyance system from the dewatering building plus improvements to the truck loading and scale alignment system.
Phase 2 and 3 – installation of a larger storage hopper capable of accommodating a full truckload of biosolids, and providing direct conveyance to the drying beds
Staff recommends City Council approve the First Amendment with HDR Engineering, in an amount of $442,700, plus extra services of $44,270, for a total not-to-exceed amount of $592,350, including $9,580 in previously authorized extra services, and extending the term to June 30, 2027, for final design and engineering of the project, including the development of construction-ready plans and specifications and bid-phase services (Attachment #2). Completing design for all three phases of the project at this time will ensure a comprehensive engineering package with no scope gaps, proper interoperability between all phases and components of the project, and also reduced overall design cost.
The preliminary project schedule is as follows:
Final Design and Engineering Spring 2026 – Winter 2027
Bid and Award (Phase 1) Summer 2027 – Fall 2027
Construction (Phase 1) Fall 2027 – Spring 2029
Bid and Construction (Phase 2) 2028 – 2029
Bid and Construction (Phase 3) 2029 – 2030
HCTP Biosolids Conveying and Storage Improvements Project (CI 5683) May 12, 2026
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The estimated project cost is as follows:
Preliminary Design Report (prev. authorized) $ 95,800 Extra Services (prev. authorized) $ 9,580
Design and Engineering – 1st Amendment (this action) $ 442,700 Extra Services (this action) $ 44,270
City Furnished Materials/Supplies (future) $ 5,000 Construction – Phase 1 (future, including contingencies) $2,902,650 Construction – Phase 2 (future, including contingencies) $4,500,000 Total Estimated Project Cost for CI 5683 $8,000,000 Community Outreach: This project will be limited to work at HCTP and is not expected to impact any neighboring residences.
This project meets City Council’s Top Ten Priorities #8 and #9, “Environmental Sustainability” and “Public Works Infrastructure Investments.” CIP PROJECT PRIORITY (as outlined in FY 2025-26 and FY 2026-27 CIP Program Budget)
Priority Three – Nice to do and would contribute to quality of life, but not essential.
LEVINE ACT (California Government Code § 84308):
This item is subject to the Levine Act. City Councilmembers who have received a campaign contribution of more than $500 (aggregated) within the preceding 12 months from a party or their agent/representative, or a financially-interested participant involved in this proceeding may do either of the following: (1) disclose the contribution on the record and recuse themselves from this proceeding; or if applicable (2) return the portion of the contribution that exceeds $500 within 30 days from the time the official knew or should have known about the contribution, and participate in the proceeding.
All parties and their agents/representatives must disclose on the record of this proceeding any aggregated contribution of more than $500 made to any Councilmember within the preceding 12 months. Councilmembers are prohibited from accepting, soliciting, or directing a campaign contribution of more than $500 (aggregated) from a party, their agent/representative, or a financially-interested participant during a proceeding and for 12 months following the date a final decision is made. In addition, a party, their agent/representative, or a financially- HCTP Biosolids Conveying and Storage Improvements Project (CI 5683) May 12, 2026
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interested participant is prohibited from contributing more than $500 (aggregated) to a Councilmember during a proceeding and for 12 months following the date a final decision is made. The completed Levine Act Form for HDR is included in Attachment #2.
COUNCIL GOAL COMPLIANCE:
Meets the following City Council goals:
C. Operate City government in a fiscally and managerially responsible and prudent manner to ensure that the City of Thousand Oaks remains one of California's most desirable places to live, work, visit, recreate, and raise a family.
F. Provide and enhance essential infrastructure to ensure that the goals and policies of the Thousand Oaks General Plan are carried out and the City retains its role and reputation as a leader in protecting the environment and preserving limited natural resources.
PREPARED BY: Paul Weinstein, Associate Analyst
Attachments:
Attachment #1 – Vicinity and Location Maps
Attachment #2 – First Amendment to Contract No. 14088-2025 with HDR DPW: 850-20\ev\Council\2026\051226\CI 5683\Biosolids Conveying and Storage Improvements staff report.docx