TO:Andrew P. Powers, City Manager
FROM:Nader Heydari, Public Works Director
DATE:June 9, 2026
SUBJECT: Purchase of Secondary Clarifier Drive Unit
RECOMMENDATION:
1. Approve budget appropriation in the amount of $67,500 from A/C #624-8250- 685-8900 (Wastewater Fund - Fixed Asset Replacement) to A/C #624-8250-685- 8400 (Wastewater Fund - Equipment Over $10K).
2. Authorize expense in the amount of $67,439.16 from A/C #624-8250-685-8400 (Wastewater Fund - Equipment Over $10K) for a secondary clarifier drive unit from WesTech Engineering, LLC (Salt Lake City, UT).
3. Find that this action is not a project as defined under the California Environmental Quality Act.
LEVINE ACT ITEM: Yes
FINANCIAL IMPACT:
$67,500 Increase to the Adopted FY 2025-26 Wastewater Fund Budget fully offset by Fixed Asset Replacement. $67,500 increase to the Adopted FY 2025- 26 Wastewater Fund Budget is requested for the replacement drive unit for a secondary clarifier. This purchase is fully offset by $67,500 in fixed asset replacement.
BACKGROUND:
The City’s 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, multimedia filtration, and disinfection. The resulting high-quality effluent is then beneficially reused for agricultural irrigation and landscape watering.
Purchase of Secondary Clarifier Drive Unit
June 9, 2026
1 5
2 7
As part of the secondary treatment process, HCTP utilizes secondary clarifiers to separate biological solids from wastewater following the aeration process.
Secondary clarifiers are critical process units that allow activated sludge to settle and separate from the process effluent before the water proceeds to tertiary filtration and disinfection. The clarifiers also return activated sludge back into the treatment process to maintain biological treatment performance.
DISCUSSION/ANALYSIS:
HCTP relies on multiple interconnected treatment processes operating continuously to maintain compliance with wastewater treatment requirements and ensure reliable plant operations. Secondary clarification is a critical component of the activated sludge treatment process and is necessary to maintain proper solids separation prior to tertiary filtration and disinfection.
The drive unit in one of the secondary clarifiers recently began to fail, creating an operational concern that requires prompt action to minimize the potential duration of process interruption at the facility. Operating for an extended period with one clarifier unavailable increases operational risk, particularly during periods of higher hydraulic loading, process upsets, maintenance activities, or emergency conditions. Restoring the clarifier to full operational status without delay is necessary to maintain treatment reliability and operational flexibility at HCTP.
The clarifier manufacturer, WesTech Engineering, LLC, verified that the replacement drive unit is proprietary equipment manufactured exclusively by WesTech Engineering, LLC and that no alternative manufacturer or distributor is authorized to supply the equipment. Therefore, the equipment purchase qualifies as a sole source procurement. The sole source designation was reviewed and approved by the City’s Purchasing Division and is maintained on file. As a result, competitive quotations were not solicited.
Staff recommends City Council approve the additional budget appropriation and authorize expense for the replacement drive unit to ensure continued reliable wastewater treatment operations at HCTP.
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.” Purchase of Secondary Clarifier Drive Unit
June 9, 2026
1 5
2 7
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- 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 signed Levine Act Disclosure Form from WesTech Engineering, LLC is included as Attachment #1.
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: Tim Mooney, WWTP Superintendent
Kim Sherman, Utilities Analyst
Attachment:
Attachment #1 – Levine Act Disclosure Form for WesTech Engineering, LLC DPW:290-10\ks\Council\2026\060926\Purchase of Secondary Clarifier Drive Unit staff report.docx