TO:Andrew P. Powers, City Manager
FROM:Clifford G. Finley, Public Works Director
DATE:March 25, 2025
SUBJECT: Hill Canyon Treatment Plant Stormwater Diversion Project (CI 5427)
RECOMMENDATION:
1. California Environmental Quality Act (CEQA): Adopt resolution adopting the Mitigated Negative Declaration (MND) and Mitigation Monitoring Plan for the Hill Canyon Treatment Plant (HCTP) Stormwater Diversion Project (CI 5427).
2. Approve the project design, plans, specifications and Addenda Nos. 1, 2 and 3 for construction of the HCTP Stormwater Diversion Project (CI 5427).
3. Award construction contract for HCTP Stormwater Diversion Project (CI 5427) to Toro Enterprises, Inc. of Oxnard, CA, in the amount of $1,249,500, plus a contingency of $124,950.
4. Approve Seventh Amendment to Professional Services Agreement Contract No. 12393-2020 with Dudek, Inc., of Encinitas, CA, for Construction Phase Support Services on the HCTP Stormwater Diversion Project (CI 5427) in the amount of $189,780 for a revised not-to-exceed amount of $460,219.77, plus extra services of $14,950.
5. Authorize expense in the amount of $1,579,180 ($1,249,500 construction contract, $124,950 construction contract contingency, $189,780 for construction support services and material testing, and $14,950 for extra services, from A/C #624-8250-682-8300 (Wastewater Fund – Capital Improvements, CI 5427).
6. Delegate authority to the City Engineer to approve changes in the design, plans, specifications, and working details of the project on work directives and change orders up to the project approved contingency amount.
LEVINE ACT ITEM: Yes
HCTP Stormwater Diversion Project (CI 5427)
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FINANCIAL IMPACT:
No Additional Funding Requested. $2,689,332 in carryover budget is included in the Adopted FY 2024-25 Wastewater Capital Fund for CI 5427.
BACKGROUND:
The City’s HCTP treats wastewater from the entire community of Thousand Oaks.
The HCTP is located in a canyon in the northwest corner of the City, located between two creeks in a natural, unimproved environment. On the east side of the facility, there is a canyon wall that drains into the HCTP (Attachment #1). A section of concrete drainage swale behind the block wall directs flow to drain inlets regularly maintained by HCTP staff as part of their storm preparedness activities.
The drain inlets connect to an existing 30-inch diameter pipeline that captures storm flows and drains them to the sludge drying beds where the storm water is pumped back to the headworks and is treated through the plant process. The stormwater collection and treatment are part of the zero-discharge storm flow capture program the City performs as part of its permit exemption.
Rainfall and storm flow have caused runoff from the canyon wall and hillside, resulting in substantial flows that frequently overwhelm the existing drain inlets.
These flows deposit natural debris (rocks, vegetation, mud) onto the HCTP parking areas and access roads, creating unmanaged drainage issues that require substantial cleanup and debris removal. The debris flows pose a risk to HCTP operations because the location of the debris flow can prevent chemical deliveries to the plant. Additionally, the stormwater volume from the canyon reduces the detention basin’s available storage capacity, which is needed for managing system flows during heavy rain events.
Historically, these stormwater flows were transported through the existing HCTP drainage system directly to the Arroyo Conejo Creek. However, as part of the zero- discharge stormwater permit, the flows are required to be directed to the equalization and emergency retention basins for treatment.
This project will construct a debris capture area and diversion channel on the eastern boundary of the plant to prevent the stormwater from entering the plant site. This will be accomplished by constructing elevated retaining walls and widening the drainage channel and by installing piping to redirect stormwater from the side canyon around the perimeter of the treatment plant. The diverted stormwater from the canyon will be channeled directly to the historical discharge point in the Arroyo Conejo Creek.
DISCUSSION/ANALYSIS:
City Council authorized bidding of the project on December 3, 2024. The Notice Inviting Bids was publicly advertised in the Thousand Oaks Acorn newspaper and posted on the City’s procurement website on December 6, 2024, per Public HCTP Stormwater Diversion Project (CI 5427)
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Contract Code Section 22037 and Thousand Oaks Municipal Code Section 3-
10.306. A total of 11 bids were received and publicly opened on February 5, 2025.
The bid results are as follows:
Bidder Bid
1. Toro Enterprises, Inc. (Oxnard, CA) $1,249,500.00
2. Environmental Construction, Inc. (Woodland Hills, CA) $1,490,164.00
3. R-HELP Construction Co., Inc. (Newbury Park, CA) $1,530,045.00
4. Los Angeles Engineering, Inc. (Covina, CA) $1,644,000.00
5. Pacific Hydrotech Corporation (Perris, CA) $1,665,200.00
6. J Vega Engineering Inc. (Oxnard, CA) $1,666,444.00
7. J.R. Filanc Construction Company, Inc. (Escondido, CA) $1,739,139.00
8. Blois Construction, LLC (Oxnard, CA) $1,750,347.00
9. Estate Design and Construction Inc. (Los Angeles, CA) $1,833,287.00
10. MMC Inc. (La Palma, CA) $1,954,000.00
11. Bosco Constructors, Inc. (Chatsworth, CA) $2,421,128.70
The lowest bid received was from Toro Enterprises, Inc. (Toro), in the amount of $1,249,500. The bid is lower than the engineer’s estimate of $1,500,000. The bid package submitted by Toro has been reviewed and found to be in order, and the bid protest period has elapsed with no formal protests received. Toro has completed similar projects successfully for the City in the past. Staff recommends awarding the construction contract in the amount of $1,249,500 to Toro, plus a contingency of $124,950.
The estimated overall project cost breakdown is as follows:
Design and Environmental Support (previously approved) $ 270,439.77 Design and Engineering Contingency (previously approved) $ 23,957.23 Engineering & Project Management Support (prev. approved) $ 100,000.00 Construction Contract (this action) $ 1,249,500.00
Construction Contingency (this action) $ 124,950.00 Construction Phase Design Support Services (this action) $ 189,780.00 Const. Phase Support Services Extra Services (this action) $ 14,950.00 Permitting and Inspection Fees (future action) $ 50,000.00 Total Estimated Cost $ 2,023,577.00
The construction phase is anticipated to start by Spring 2025 and is expected to be fully completed by early 2026.
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The project plans and specifications were completed by Dudek, Inc. (Dudek) and approved by City staff in Fall 2024. They are available for review upon request to the Public Works Department by e-mail at [email protected] or by phone at (805) 449-2400.
Design Support Services During Construction
Dudek is the project engineer of record and will provide design support services during the project's construction. These support services will include responding to requests for information, reviewing material submittals, preparing the final project punch list, and preparing record drawings upon completion. The services will also include field observation and material testing/inspection throughout the construction period. In addition, Dudek will provide environmental/biological services during the preconstruction and construction phases of the project. This is required per the project environmental document to ensure the requirements of the environmental permits are met, including biological monitoring and permit compliance documentation during and after project construction. Staff recommends approval of the Seventh Amendment to Contract No. 12393-2020 with Dudek for $189,780 (Attachment #2) for a revised not-to-exceed amount of $460,219.77 plus extra services of $14,950.
Environmental Review
As required under the provisions set forth in Section 15063 of CEQA Guidelines, an Initial Study was prepared for the HCTP Stormwater Diversion Project (CI 5427). The Initial Study was prepared by Dudek and evaluates the potential effects of this project on the environment. Although the Initial Study determined that the project could have a potentially significant impact on the environment for certain receptors, the project design will reduce the impacts, and feasible mitigation measures have been identified that would either avoid or reduce impact to a level of insignificance or less than significant with mitigation. This project is within the HCTP's boundary, but a small section of grading is needed for the necessary improvements. Additionally, an oak tree located within the treatment plant boundary will be removed for the required drainage improvements, which will be replaced in accordance with the City’s required 3:1 oak tree removal replacement ratio and the draft MND.
The draft MND was prepared and published in August 2023 and included a 30-day public comment period. Once the public comment period for the draft MND ended, staff responded to all written comments that were received. A Final MND and Mitigation Monitoring Reporting Plan has been prepared for the proposed project in compliance with the provisions set forth in Section 15070 of the CEQA Guidelines (Attachment #3). The work location is near Conejo Open Space Conservation Agency (COSCA) property, and therefore coordination with COSCA HCTP Stormwater Diversion Project (CI 5427)
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occurred during the environmental review and will continue throughout construction.
Staff recommends City Council adopt a resolution adopting the MND and Mitigation Monitoring Plan for the HCTP Stormwater Diversion Project (CI 5427) (Attachment #4).
This project meets City Council’s Top Ten Priorities #7, “Public Works + Infrastructure Investments.”
Community Outreach: This project will be limited to work at the HCTP and is not expected to impact any neighboring residences. The work will be on the east end of the plant and will have a limited impact on plant operations. Construction- related impacts to hiking trail users will be minimal.
CIP PROJECT PRIORITY (as outlined in FY 2023-24 and 2024-25 CIP Program Budget)
Priority One – Addresses health and safety, legal and regulatory requirements, or a top City Council Priority.
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.
COUNCIL GOAL COMPLIANCE:
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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 – Seventh Amendment to Contract No. 12393-2020 with Dudek, Inc.
Attachment #3 – Final Mitigated Negative Declaration
Attachment #4 – Resolution Adopting MND for CI 5427, including Mitigation Monitoring Program
Documents Provided Under Separate Cover:
#1 – Project Plans and Specifications
DPW: 850-20\ev\Council\032525\CI 5427\HCTP Stormwater Diversion Project staff report.docx