HCTP Slope Stabilization Project

The City of Thousand Oaks Hill Canyon Treatment Plant (HCTP) is in a canyon environment in the west-northwest section of the City of Thousand Oaks. The HCTP is located between two creeks in a natural, unimproved environment. The treatment plant's original construction required an access road to be installed along the toe of a cliff adjacent to the combined creek boundary. Farther in the canyon, the continued expansion of the treatment plant has required improvements to be placed adjacent to a cut slope on the east side of the HCTP. In 2022/2023, the City installed a post and beam retaining wall along a portion of the HCTP. During that installation, the Contractor had to cut the existing slope to a point where the long term stability of the slope material is in question. Additionally, when the original access road was constructed at the entrance to the canyon, a large rock face exists adjacent to the access road. The stability of this rock façade is in question. Over time, the rock façade has deposited material onto the access road. The City seeks professional engineering services from a qualified and experienced consulting firm to provide design and engineering services to address slope stability at two locations (please refer to Attachment A- Slope Stabilization Site Plan) . Outline potential slope stability options for consideration by the City. The work will be completed in three phases, which are to be included in the consultant's qualifications and will be considered during the RFP process: (1) Preliminary Design Report (PDR) Preparation Phase; (2) Final Design Phase development of construction documents (plans, specifications, engineer's estimate), and engineering services during the bid process; (3) Construction Phase, which entails providing engineering support services during construction of the project. At this time, only the efforts associated with the first phase are to be included in this proposal. Depending on the outcome of the PDR, the selected consultant may be aske to submit a fee proposal for Phases 2 and 3 to implement the City's selected stability solution. The services to be included in this RFP/Q shall include but not be limited to the following: coordination with City HCTP operations staff and City engineering staff; research/review the record drawings and site conditions; obtain geologic/geotechnical information of the existing slope materials and properties at the access road location (the HCTP site already has a geology/geotechnical report for the retaining wall) and provide recommendations on the proposed stabilization process, attend monthly coordination meetings as needed with the City’s Project Manager, preparation of a draft and final PDR.