TO:Andrew P. Powers, City Manager
FROM:Clifford G. Finley, Public Works Director
DATE:November 14, 2023
SUBJECT: Unit W Wastewater Interceptor Improvements (CI 5445) RECOMMENDATION:
1. Authorize staff to advertise the Unit W Wastewater Interceptor project (CI 5445) for construction bids.
2. California Environmental Quality Act (CEQA): A Mitigated Negative Declaration was approved for this project by City Council on February 22, 2022.
FINANCIAL IMPACT:
No Additional Funding Requested. Minimal staff time and costs required to advertise for bids are included in the Adopted FY 2023-24 Wastewater Fund Budget. $1,700,000 is included in the Adopted FY 2023-24 Wastewater Capital Fund Budget and $1,616,377 was carried over from FY 2022-23 to FY 2023-24 for CI 5445, for a total available budget of $3,316,377. The estimated total project cost for CI 5445 is $3,374,000. Additional funding for construction costs will be requested at the time of construction contract award depending on bids received.
BACKGROUND:
The Hill Canyon Treatment Plant (HCTP) is located at 9600 Santa Rosa Road and provides tertiary-level wastewater treatment for the community. As part of the overall wastewater collection and treatment system, large-diameter wastewater interceptor pipelines were installed to transport the wastewater from the community and deliver it to the HCTP. The Unit W Wastewater Interceptor is a gravity collection pipeline that originates near The Oaks Mall and transports a large volume of wastewater along the Arroyo Conejo Creek to the HCTP (Attachment #1).
The Unit W pipeline was installed in the 1960s and improvements have been made over the decades. In the lower portion of the interceptor, the original 1960s Unit W pipeline consisted of a 30-inch diameter pressurized pipeline with two major wastewater access structures (Structure W-1 and Structure W/F). The structures enable the wastewater interceptors to be accessed by staff.
Unit W Wastewater Interceptor Improvements (CI 5445)
November 14, 2023
8 5
2 This project will review the existing condition of the two pipelines towards the south headworks at the HCTP, a distance of approximately 5,000 feet. The project also includes installing new access holes and a temporary wastewater bypass pipeline to HCTP headworks so closed-circuit television (CCTV) work can be performed on the inside of the wastewater pipelines. In addition, three of the existing isolation valves are non-functional due to mechanical failure. Replacement of these valves can be challenging from a permitting and feasibility standpoint, so they have been included as part of this project. The valves are buried in the canyon and therefore must be excavated to be replaced. Due to the length of the pipelines on the Unit W alignment and the limitations of the CCTV equipment, this project will install five to seven access tee fittings at key locations. The 42-inch pipeline will have two to three access points installed, and the second parallel pipe will have three to four access points installed. The access points will be installed when the flows are transferred to the other existing pipeline. Once the access points are completed and no longer needed on this project, they will be closed and left in place for future use.
This condition assessment of the project is the first phase of a two-phase project. Once this project is completed and the internal pipeline CCTV information is obtained, staff will determine the need for a second phase of this project, which is a separate future capital project under CI 5681.
On August 27, 2019, AECOM Technical Services, Inc. (AECOM), a professional engineering firm, was selected through a competitive Request for Proposals (RFP) process to prepare an asset assessment of a portion of the Unit W Pipeline Project. In May 2020, a first amendment was approved, which extended the contract date. A second amendment was approved by City Council on January 26, 2021, to add $178,500 for design services. The third amendment was approved in October 2021 to extend the agreement to June 30, 2022. A fourth amendment was approved in June 2022 to add $13,249 for additional design services. A fifth amendment was approved in May 2023 to extend the agreement to December 31, 2024. A sixth amendment was approved by City Council on July 11, 2023, to add $31,000 for value engineering and design clarifications/modifications.
On January 24, 2023, City Council authorized staff to advertise the project for construction bids. Bids were opened on March 1, 2023, and were higher than anticipated. Because of the high construction bids, staff recommended that City Council reject all bids at the April 4, 2023, City Council meeting. Staff consulted with the contractors who submitted bids and determined there were operational questions as well as regulatory requirements that were not clear on the plans. Staff worked with the design consultant to make changes to the plans and specifications to clarify and address the issues raised by the prospective contractors.
Unit W Wastewater Interceptor Improvements (CI 5445)
November 14, 2023
8 5
2 DISCUSSION/ANALYSIS:
Staff worked with the design consultant to implement design and construction document clarifications and value engineering that are intended to result in cost savings for the project. The project plans and specifications have been modified accordingly. The project plans and specifications were completed by the design consultant in early November 2023, and are available for review upon request to the Public Works Department by e-mail at [email protected] or by phone at (805) 449-2400.
Staff recommends advertising the project for bids. Once bids are received, staff will make a recommendation at a future City Council meeting for award of the construction contract. In the meantime, staff is procuring the three long lead plug valves necessary for the project, so they are delivered in time for the construction of the project in 2024.
The tentative schedule for completion of the project is as follows:
Bidding Dec. 2024 – Jan. 2024
Award of construction contract Winter 2024
Start of construction Spring 2024
Construction completion Fall 2024
The estimated project costs are as follows:
Design and Engineering (previous) $ 300,000
Phase 1 Construction Estimate (including contingency) $3,074,000 Total Estimated Cost $3,374,000
The overall project cost (including contingencies, design services during construction/testing, and project management) is estimated at $3,374,000. Additional appropriation at the time of construction award will be requested if necessary, depending on the actual bids received.
As part of the design efforts on the project, the consultant prepared the Mitigated Negative Declaration in accordance with the CEQA guidelines. City Council adopted the Mitigated Negative Declaration and Mitigation Monitoring Program for the project on February 22, 2022.
Regulatory permits were previously obtained by Padre Associates, Inc. for the work on this project. Padre Associates, Inc. was retained by the City to prepare the necessary environmental documents needed to secure the regulatory permits Unit W Wastewater Interceptor Improvements (CI 5445)
November 14, 2023
8 5
2 from the Regional Water Quality Control Board, the US Army Corps of Engineers, and California Fish and Wildlife. The regulatory permits are in place and will be included in the Contract Documents for the prospective contractor.
This project meets City Council’s Top Ten Priorities #6, “Public Works + Infrastructure Investments.”
Community Outreach: This project will be limited to work in the canyon adjacent to the HCTP where the Unit W pipelines are located and is not expected to impact any neighboring residences. The work will be at the south end of the plant and will have limited impact to plant operation. Construction related impacts to hiking trail users will be minimal.
CIP PROJECT PRIORITY (as outlined in FY 2023-24 and FY 2024-25 CIP Program Budget)
Priority Two – Necessary, but not essential, and there could be consequences if deferred.
COUNCIL GOAL COMPLIANCE:
Meets the following City Council goal:
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
Attachment:
Attachment #1 – Vicinity and Location Maps
DPW: 850-20\cg\pw\ev\Council\2023\111423\CI 5445\ HCTP Unit W Wastewater Interceptor Improvements staff report.docx