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CC SR 20250218 03 - Landslide UpdateCITY COUNCIL MEETING DATE: 02/18/2025 AGENDA REPORT AGENDA HEADING: Regular Business AGENDA TITLE: Consideration and possible action to receive an update report on the Abalone Cove Landslide Hazard Abatement District’s (ACLAD) Deep Dewatering Well Plan. RECOMMENDED COUNCIL ACTION: (1)Receive and file an update on ACLAD’s Deep Dewatering Well Plan including the number of wells and instrumentation to be installed using the City’s $1.6 million loan; as well as annual operations and maintenance costs. FISCAL IMPACT: There is no fiscal impact associated with receiving and filing an update to ACLAD’s Deep Dewatering Well (DDW) Plan. On July 2, 2024, the City Council approved a loan to ACLAD in the amount of $1.6 million budgeted in the Capital Infrastructure Program (CIP) Fund, which is sufficient to implement much of the DDW Plan, according to ACLAD’s estimates. VR Adopted Budget on June 18, 2024: $0 Additional Appropriation Approved on July 2, 2024: $1,610,000 (ACLAD) and $1,917,500 (KCLAD) Account Number(s): 330-400-0000-7201 (CIP Fund – Debt Issued) VR ORIGINATED BY: Ramzi Awwad, Director of Public Works REVIEWED BY: same as above APPROVED BY: Ara Mihranian, AICP, City Manager ATTACHED SUPPORTING DOCUMENTS: A.July 2, 2024 City Council Meeting on Financial Assistance Loan Agreements Between KCLAD and ACLAD (Page A-1). https://rpv.granicus.com/MetaViewer.php?view_id=5&clip_id=4604&meta_ id=120784 B.February 4, 2025 City Council Meeting on ACLAD Draft DDW Plan (Page B-1). rpv.granicus.com/MetaViewer.php?view_id=5&clip_id=4724&meta_id=125 141 1 BACKGROUND: On July 2, 2024, the City Council approved a loan of $1.6 million for the Abalone Cove Hazard Abatement District (ACLAD) for improvements and repairs to existing dewatering wells (not DDW) of approximately $1 million and surface drainage improvements of $610,000. (Attachment A) Since that time, ACLAD has been focusing on surface drainage improvements using their existing budget. On January 21, 2025, the City Council directed Staff to work with ACLAD to develop a DDW Plan within ACLAD’s jurisdictional boundary that would be financed by the City at a not to exceed cost of $5 million, including $1.6 million from the City Council authorized loan, with the balance in the form of a loan or grant as determined by the City Council at a future date. On January 28, 2025, staff facilitated a conference meeting with two ACLAD Board Members; the ACLAD geologist, Scott Kerwin of WSP Global, Inc.; the City Geologist firm Cotton, Shires and Associates (CSA); and the City’s project engineer/geologist for the landslide project, Geo-Logic Associates, Inc. (GLA). As a result of the conference, ACLAD developed a concept ACLAD DDW Plan acceptable to CSA and GLA in concept. On February 4, 2025, staff presented the concept DDW Plan to the City Council that ACLAD Board Members believe up to 10 DDW could be installed in the amount of the City’s loan at $1.6 million (Attachment B). That evening, the City Council directed Staff to work with ACLAD to further define the DDW Plan by affirming the recommended number of DDW, defining the recommended geologic data collection instrumentation and associated costs, and developing cost estimates for operations and maintenance of the plan. DISCUSSION: On February 12, 2025, staff facilitated another conference with ACLAD Board Chair; Scott Kerwin, CSA, and GLA. As a result of the conference, ACLAD further defined the concept ACLAD DDW Plan, with concurrence from CSA and GLA. The DDW Plan is conditioned upon sequential implementation with data collected from each step that would be used to inform revisions and subsequent steps of the DDW Plan. Scope The DDW Plan consists of eight to ten new DDWs at depths of approximately 250 feet, along with two monitoring wells. The DDWs consist of slotted PVC pipe and a pump installed above the slip plane which extracts water from all levels in the well. The monitoring wells consist of grouted in-place water pressure gauges (vibrating wire piezometers that measure changes in wire tension) at multiple levels to measure water pressure pushing up on the slip plane. An initial measurement is recorded as an existing condition for comparison to measurements after pumping. 2 Figure 1 shows the priority order of the DDWs and the approximate locations. The locations, which are approximate and subject to revisions in the field, were selected based on the following criteria: • Proximity to historically most productive ACLAD dewatering wells • Gaps in dewatering areas • Expected survivability of wells based on nearby geologic expressions • Access for well drilling and associated equipment • Availability of drainage infrastructure or relative ease of installation thereof As the ACLAD DDW Plan is implemented, staff will report the effect of the plan on land movement to the City Council. Data from Global Positioning System (GPS) surveys measuring movement of nearby points, hydraulic pressure gauge changes, and surface expressions will be used to assess effectiveness of the ACLAD DDW Plan. Figure 1: ACLAD DDW Plan Subject to Field Modifications and Revisions During Implementation Schedule Because data from each DDW installation will be used to inform modifications to the subsequent DDW, the DDW Plan is likely to unfold over a few months. The City has procured project management/construction management services to assist ACLAD with implementation of their DDW Plan, as approved by the City Council on February 4, 2025 (the cost of which is not to exceed $100,000). 3 Budget ACLAD estimates the cost of each DDW to be between approximately $140,000 and $200,000; and each monitoring well to be approximately $125,000. Although the total estimated installation cost of the ACLAD DDW Plan may exceed the currently approved loan amount of $1.6 million, staff recommends that the City Council defer additional funding at this time because there is sufficient funding to implement much of the DDW Plan, according to ACLAD’s estimates. Staff will provide the City Council with updates on expenditures and initial results of the ACLAD DDW Plan. ACLAD estimates the annual operations and maintenance cost to be approximately $550,000 for Fiscal Year 2025-26. ACLAD Loan Update On August 20, 2024, the City received the signed loan agreement from ACLAD in the amount of $1.6 million and this amount remains the FY 2024-25 CIP budget and is available for disbursement (no disbursement of funds have occurred to date). The loan has a 12-year term with a 2.5% interest rate, and the first estimated payment is scheduled for December 2025, based on the amount disbursed to ACLAD. Based on the preliminary discussions with ACLAD, they plan to request an extension for the first payment since no amount has been disbursed yet in FY 2024-25. ADDITIONAL INFORMATION: At the February 4, 2025 City Council meeting, Councilmember Lewis requested staff to work with ACLAD and provide additional financial information on ACLAD’s 10-year history, including inflows and outflows transactions. Staff will collect the requested financial data from ACLAD and include the information in the March 18, 2025 staff report. CONCLUSION: In response to the City Council’s direction ACLAD’s DDW Plan of eight to ten new DDWs at depths of approximately 250 feet, along with two monitoring wells with water pressure gauges. ACLAD estimates the cost of each DDW to be between approximately $140,000 to approximately $200,000; and each monitoring well to be approximately $125,000. ACLAD estimates the annual operations and maintenance cost to be approximately $550,000 for Fiscal Year 2025-26. The City Council is being asked to receive and file this update report on ACLAD’s DDW Plan. ALTERNATIVES: In addition to Staff recommendation, the following alternative actions are available for the City Council’s consideration: 4 1.Direct staff not to disburse the loan funds for ACLAD’s DDW Plan thus requiring the loan to be used on the original scope of work detailed earlier in this report. 2.Take no action. 3. Take other action, as deemed appropriate. 5