Engineering Design Services for the Fassler Tank Replacement Project

REQUEST FOR PROPOSALS ENGINEERING DESIGN SERVICES FOR THE FASSLER TANK REPLACEMENT PROJECT Release Date: March 22, 2024 Proposal Submission Deadline: April 22, 2024 Contact Person: Adrianne Carr, General Manager Cc: Jonathan Sutter, District Engineer North Coast County Water District 80 Eureka Square Suite #219 Pacifica, CA 94044 www.nccwd.com http://www.nccwd.com/ REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 2 Release Date: Friday, March 22, 2024 Closing Date: Monday, April 22, 2024, 3:00 PM, late proposals will not be considered Contact Person: Adrianne Carr, General Manager Email: acarr@nccwd.com Phone: 650.355.3462 North Coast County Water District 80 Eureka Square Suite #219 Pacifica, CA 94044 Cc: Jonathan Sutter., District Engineer Email:

href="mailto:jsutter@ekiconsult.com">jsutter@ekiconsult.com Phone: 650.292.9099 PURPOSE: North Coast County Water District (NCCWD or District), the public agency responsible for water distribution in Pacifica, California, requests proposals from highly qualified and experienced engineering firms (Consultant) to prepare a detailed design of a 1.2 million gallons (MG), partially buried AWWA D110 Type I Prestressed Concrete Tank to replace an existing 0.5 MG welded steel tank located at 1186 Fassler Avenue in Pacifica, California (Site). The project involves the demolition of the existing 0.5 MG storage tank and installation of the new 1.2 MG tank, along with associated valves, piping, power, supervisory control and data acquisition (SCADA) system, and site improvements. The purpose of this solicitation is to request proposals that will enable the District to determine which Consultant to select the most qualified Proposer with the highest score from the evaluation of its proposal. BACKGROUND Constructed in 1962, the current Fassler Tank is a 0.5 MG welded steel tank (58-foot diameter by 24-foot side water depth) and is supplied by Royce and Park Pacifica booster pump stations. It is the highest tank in the southern portion of the NCCWD system with a base elevation of 709 feet. The District has determined that the Fassler Tank has reached the end of its useful life and requires replacement with a 1.2 MG capacity tank to meet operational, emergency, and fire flow requirements. NCCWD has completed a preliminary geotechnical investigation, topographic survey, and siting study for the Fassler Tank Replacement Project (Siting Study; see Attachment A). A boundary survey was completed in 2007 and reflects current boundaries and property ownership. Based on the findings of the Siting Study, NCCWD has decided to proceed with the detailed design for a 1.2 MG, partially buried, AWWA D110 Type I Prestressed Concrete Tank at the Fassler Tank site to replace the existing tank. The project will also include tank demolition and improvements to the Fassler Tank site to facilitate ongoing maintenance. The project is also anticipated to include improvements to Baquiano Trail, located along Fassler Avenue and part of the Golden Gate National Recreation Area (GGNRA) managed by the National Parks Service (NPS), to maintain safe trail access during construction. The successful firm will have relevant technical expertise and will possess the required resources and capabilities to support engineering and related disciplines to design the new 1.2 MG water storage tank. The firm will also demonstrate successful experience providing technical studies, concept designs, final designs, and support services during bid and construction phases. mailto:sdalton@nccwd.com mailto:sdalton@nccwd.com mailto:jsutter@ekiconsult.com REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 3 Please read this entire RFP package and include all requested information in your proposal. SCOPE OF WORK The following tasks describe the scope of services to be performed by the selected Consultant for the Fassler Tank Replacement Project. Task 1: Project Management And Coordination Throughout all tasks, the Consultant shall be responsible for project administration and management activities including, but not limited to, the following: • Project administration, monitoring, and coordination. • Participation in project kick-off meeting, monthly progress meetings, and design review meetings (include effort for design review meetings under Task 3). • Preparation meeting summaries for all above meetings. • Performance of quality assurance/quality control (QA/QC) reviews for the project. • Performance of project communications. • Preparation of project schedule, including monthly updates1. • Prepare monthly project progress reports and invoices. • Review California Environmental Quality Act (CEQA) compliance documentation (to be prepared by the District). Task 1 Deliverables: • Monthly progress reports and invoices • Project schedule, updated monthly • Agenda and meeting minutes for all design review meetings • Decision log updated after each meeting Task 2: Supplemental Site Investigations, Document Review, And Data Collection As part of prior planning work, the District has completed preliminary topographic surveying, a geotechnical investigation, and a siting study (see Attachment A). NCCWD will provide the relevant files from prior work efforts, including all AutoCAD files, to the selected Consultant. The Consultant shall carry out the following subtasks to provide information to advance the design. • Collect, evaluate, and review existing records, including but not limited to drawings, reports, maps, data, and other documents relevant to the project. • Coordinate with client to obtain necessary information on the proposed project description and site requirements. • Make necessary field visits to Fassler Tank site to collect data as needed. • Conduct supplemental surveying and mapping, including property boundaries, right-of- way, easements, as deemed necessary by the Consultant. At a minimum, the survey shall produce site plans which include roads and trails, elevations, existing facilities, equipment, utilities, trees, boundaries, and other information relevant to the project. • Conduct supplemental geotechnical investigations of soils and base rock as deemed necessary by the Consultant for the new water tank and other new structures and equipment pertaining to the project. REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 4 • Coordinate with various public utility agencies requesting existing utility mapping and other applicable issues for the project area. • Prepare a utility potholing plan and conduct potholing for utilities with potential conflicts. • Participate in meetings with NPS to determine their requirements for trail access during construction. Task 2 Deliverables: • Topographic survey site plan and utility base map in electronic format (PDF and DWG) • Geotechnical report in electronic format (PDF) • Potholing plan and results Task 3: Project Design And Bid Document Preparation Consultant will be responsible for all geotechnical, civil, structural, electrical, and mechanical engineering related to the replacement of Fassler Tank facilities, including ancillary piping, instrumentation, control system, and site improvements. The Consultant will be responsible for preparing and providing all necessary bid documents and drawings suitable for bidding and construction, in addition to meeting environmental permitting requirements. The design will be conducted in the following phases. Consultant will provide full-size drawings and digital files for review, conduct workshop meetings with Client staff at the 30%, 60% and 90% design milestones, and prepare 100% bid set (engineering drawings and technical specifications) for bidding and construction. Task 3.1 – Preliminary Design Report and Drawings (30% Design Submittal) The 30% preliminary design report will consist at a minimum of the following: • Confirmation of tank dimensions and elevations including tank diameter, height, floor elevation, and maximum operating level. Evaluation will be based on tank footprint, civil/site improvements needed such utility relocation and retaining wall, D110 Type I tank constructability requirements. • Develop 30% design plans showing existing utilities, proposed water tank and piping facilities, site improvements and grading. • Tank piping and appurtenance sizing. • Tank electrical and instrumentation requirements. • Site and civil improvements, including access road and trail improvements and utility relocation, if needed, to accommodate construction activities and proposed tank footprint. Evaluation of retaining wall, if needed. Evaluation of space available for precast tank contractor laydown area. Site drainage improvements. • Demolition requirements for the existing tank. • Preliminary construction sequencing plan. • Preliminary engineer’s opinion of probable construction costs (OPCC). • Evaluation of regulatory requirements for tank design and construction. • Identification of any permitting agencies, if any, and their submittal requirements and prepare necessary permit applications. The 30% design submittal shall serve as the basis for CEQA compliance, which will be provided by the District outside of this scope of work. A design review meeting shall be scheduled with the District to review the comments for the 30% design submittal. REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 5 Task 3.1 Deliverables: • Preliminary Design Report in digital PDF format. • One (1) set of full-size 30% design plans and digital copies in PDF format. • 30% Design review meeting agenda and minutes. Task 3.2 – Design Development Submittal (60% Design Submittal) The 60% design submittal will consist at a minimum of the following: • Demolition and Temporary Plans identifying staging and stock piling areas, facilities to be removed, and areas to be impacted by construction activities. • Structural design of the tank. • Civil site plans identifying the elevation of the tank floor slab and final grades around the tank and necessary drainage improvements. • Piping plans including valving and connection piping details. • Tank Pipe Connection Details required based on seismic design consideration and recommendation. • Tank plans showing location of hatches, exterior and interior ladders, handrails, vent, inlet, outlet, drain, overflow, etc. • Electrical/Instrumentation and control system plans. • Erosion and sediment control plan. • Client’s standard front-end documents, bid forms, technical specifications, and other related documents for bid. • Update of engineer’s OPCC. A design review workshop shall be scheduled with District staff to review the comments for the 60% design submittal. Task 3.2 Deliverables: • One (1) set of full-size 60% design drawings, technical specifications and contract documents, and digital copy in PDF. • One copy of the 60% engineer’s OPCC and digital copy in PDF. • 60% Design review meeting agenda and minutes. Task 3.3 – Design Submittal (90% Design Submittal) • Further development of plans to incorporate the 60% design submittal comments and any environmental requirements identified as part of CEQA compliance efforts to be performed by the District. • Prepare complete and comprehensive technical specifications and contract documents. • Prepare the 90% engineer’s construction cost estimate with quantities. • Participate in the 90% review workshop with District staff to review the comments for the 60% design submittal. REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 6 Task 3.3 Deliverables: • One (1) set of full-size 90% revised design drawings, technical specifications and contract documents, and digital copy in AutoCAD and PDF. • One copy of the 90% engineer’s construction OPCC with quantities, and digital copy in PDF. • 90% Design review meeting agenda and minutes. Task 3.4 – Final Design Submittal (100% Design Submittal) • Incorporate the 90% Design Submittal Comments. • Complete and comprehensive 100% design plans and specifications. • Prepare the final engineer’s construction cost estimate with quantities. Task 3.4 Deliverables: • Four (4) full-size sets of the 100% final design for bid and digital copies in PDF. The submittal shall include full-size stamped and signed final drawings, specifications and bid documents. • Submit all digital files (AutoCAD, MS Word, MS Excel, etc.) for the project. Task 4: Bid Assistance Consultant will assist District in the bidding process for the project and provide the following: • Prepare all necessary bid documents and drawings. • Conduct pre-bid conference/site visit and prepare agenda and meeting minutes. • If necessary, prepare addenda during the bid period to be distributed by the District. • Respond to bidder’s technical questions during the bidding period. • Assist in analysis of bids received and in award of the construction contract. • Upon Contractor selection, prepare six (6) sets of Conformed Construction Documents. Task 4 Deliverables: • Pre-bid meeting agenda and minutes • Addenda (assume up to 3 addenda) • Responses to bidder’s technical questions • Bid review summary email • Four (4) full-size sets of the Conformed Construction Documents and digital copies in PDF. The submittal shall include full-size drawings, specifications and bid documents. ORGANIZATION OF PROPOSALS District requests that Proposing Firm’s proposals be organized as follows: Technical Proposal 1) Cover Letter: The Consultant shall provide a cover letter signed by the project manager and a company principal committing the Consultant to the Project and performance on the Project. 2) Introduction: Proposal will state the Consultant’s understanding of the work tasks and report produced as a part of the inspection. Proposal will state the firm's general experience, capabilities and approach or approaches generally used in inspections similar to those items addressed in this RFP. REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 7 3) Description of Firm's Experience: The Consultant shall provide a description of the firm's and any subconsultants’ experience, including a brief history, types of services provided, and experience in providing similar services as those requested in this RFP. List at least three similar projects completed in the last 10 years, including project description and details key staff members, and references of persons, firms, or agencies that the District may contact to verify the experience of the Consultant and key staff members. 4) Project Approach: The Proposal shall provide a description of the Consultant’s implementation plan with quality control procedures and proposed project schedule including a list of tasks and deliverables. 5) Project Team: Identify key personnel assigned to the project and describe their respective role(s) and responsibilities. Provide resumes for all key personnel assigned to the project in an appendix. 6) Level of Effort: The Consultant shall submit a table showing the number of hours by task for each project personnel. 7) Comments on Professional Services Agreement: The Proposal must identify any modifications to the attached Professional Services Agreement (Attachment B) the Consultant will request prior to entering into an agreement with the District. 8) Other pertinent information Fee Proposal The Consultant shall provide a fee proposal submitted in a separate PDF. The Fee Proposal shall include: • A spreadsheet which shows in detail the number of hours by task for each project personnel, the total number of hours for each task and total number of hours for each project personnel, the hourly rate for each personnel, the lump sum dollar cost for subconsultants and other direct costs, the total dollar cost for each task, and the total not-to-exceed fee for the project. • Consultant and subconsultant fee schedules that will be valid for the duration of the project. Fees paid to Consultant will be on a time and materials basis up to the negotiated maximum amount per signed contract. Any extra work deemed necessary by the Consultant must be pre-approved and authorized by the District in writing. No payment will be made on any unauthorized work performed by the Consultant or Subconsultants. TERMS AND CONDITIONS 1) Consultant questions during Proposal Process: Proposing firms are encouraged to ask questions to strengthen proposals to the District. Please email your intention to respond and provide all inquiries in writing via email to Adrianne Carr at acarr@nccwd.com and cc Jonathan Sutter at jsutter@ekiconsult.com. Questions will be accepted up to 3:00 pm Pacific Time on Friday, April 5, 2024. All inquiries and responses will be emailed to all Proposing Firms who indicate their intention to respond to the RFP. Inquiry sources will remain anonymous. 2) Proposals shall remain effective for ninety (90) days beyond the submittal date. 3) Limitation: The Request for Proposals (RFP) does not commit the District to award a contract, to pay any cost incurred in the preparation of the firm’s RFP response, or to procure or contract for services or supplies. The District reserves the right to accept or reject any or all RFP responses received as a result of this request, to negotiate with any/all qualified Consultants, or to cancel all or part of this RFP. 4) Award: The firm/entity chosen may be required to participate in negotiations and to submit such revisions of its proposals as may result from negotiations. The District reserves the right to award a mailto:acarr@nccwd.com mailto:jsutter@ekiconsult.com REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 8 contract/select a service provider without discussion based upon the initial proposals. 5) Signature: The consultant’s RFP response shall provide the following information: name, title, address, and telephone number of individuals with authority to bind the service provider and who may be contacted during the period of proposal evaluation. The consultant’s RFP response shall be signed by an official authorized to bind the consultant. 6) All material submitted in response to this RFP shall be considered the property of the District and may be used by the District for any purpose. 7) Proposals received by the District will not be returned to the Consultant. 8) Proposing Firms will not be compensated for any expenses incurred in the process for responding to this RFP or, if requested, in submitting further information or appearing for an interview. 9) Proposing Firm must provide a certificate for Worker's Compensation insurance and liability insurance for those performing onsite services, to Districts standards. EVALUATION CRITERIA The District will evaluate proposals evaluated based on the following factors with points by category as shown: • Firm Qualifications: Technical experience in performing work of a similar nature, experience working with public agencies, record of completing work on schedule, strength and stability of the firm, and assessments of client references (10 points). • Team Qualifications: Experience of and references for key team members on assignments, similar in complexity and requirements (30 points). • Demonstrated Understanding of the Project Requirements: Familiarity with available construction methods, limitations and benefits and recognition of potential project challenges (25 points). • Defined Scope and Approach: Appropriate tasks and deliverables in scope of work. The proposed schedule is responsive and realistic (25 points). • Overall Responsiveness to the RFP and quality of submission (10 points). SELECTION PROCESS District staff will evaluate each proposal against the Evaluation Criteria and bring recommendations to the Board of Directors, who will in turn make a final decision on the selection of the Consultant and authorize the District General Manager’s execution of a contract with the selected Consultant to perform the requested services. The District anticipates the following schedule for the selection process: Friday, March 22, 2024 Release of RFP Friday, April 5, 2024 Written questions due (optional) Wednesday, April 10, 2024 Responses from District Monday, April 22, 2024 RFP responses due not later than 3:00pm PST April 23-April 29, 2024 RFP Evaluation by Staff April 30-May 8, 2024 Negotiation with selected Consultant Wednesday, May 15, 2024 Award of Contract by Board of Directors Thursday, June 1, 2024 Notice to proceed (approximate) REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project 9 PROPOSAL SUBMITTAL Email submission of proposals must be received by the District not later than 3:00 pm on Monday, April 22, 2024. Proposals and all inquiries relating to this RFP should be emailed to: Andrianne Carr, General Manager acarr@nccwd.com Please cc: Jonathan Sutter, District Engineer jsutter@ekiconsult.com ATTACHMENTS Attachment A - Fassler Tank Siting Study (Brown and Caldwell, 2023) Attachment B - Sample Agreement for Professional Services mailto:acarr@nccwd.com mailto:jsutter@ekiconsult.com REQUEST FOR PROPOSALS (RFP) Fassler Tank Replacement Project ATTACHMENT A Fassler Tank Siting Study (Brown and Caldwell, 2023) Fassler Tank Siting Study Prepared for North Coast County Water Distr ic t Pacif ica, CA September 28, 2023 11020 White Rock Road, Suite 200 Rancho Cordova, CA 95670 Fassler Tank Siting Study Prepared for North Coast County Water Distr ic t Pacif ica, CA September 28, 2023 ii Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Table of Contents Executive Summary .................................................................................................................................... vi 1. Introduction ...................................................................................................................................... 1-1 1.1 Background ............................................................................................................................ 1-1 2. Fassler Tank Alternatives ................................................................................................................ 2-1 2.1 Alternative Details .................................................................................................................. 2-1 3. Tank Evaluation ................................................................................................................................ 3-1 3.1 Constructability ...................................................................................................................... 3-1 3.2 Seismic Performance ............................................................................................................ 3-7 3.3 Operation and Maintenance ................................................................................................. 3-7 3.4 Geotechnical Considerations ................................................................................................ 3-8 4. Preliminary Cost Estimates .............................................................................................................. 4-1 4.1 Estimated Construction Costs for Tank Alternatives ........................................................... 4-1 4.1.1 Estimate Assumptions ............................................................................................ 4-2 4.1.2 Alternative Specific Estimating Assumptions ........................................................ 4-3 4.1.3 Estimating Exclusions ............................................................................................. 4-3 4.1.4 Construction Cost Summary ................................................................................... 4-4 4.2 Life Cycle Cost Analysis ......................................................................................................... 4-5 5. Findings and Recommendations .................................................................................................... 5-1 5.1 Comparison of Alternatives ................................................................................................... 5-1 6. Limitations ........................................................................................................................................ 6-1 7. References ....................................................................................................................................... 7-1 Appendix A: Geotechnical Report ................................................................................................................ A Appendix B: DN Tanks Budgetary Estimate ................................................................................................ B Appendix C: Cost Estimates ......................................................................................................................... C Fassler Tank Siting Study Table of Contents iii Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 List of Figures Figure 1-1. Project location map ............................................................................................................. 1-2 Figure 1-2. Project site map .................................................................................................................... 1-3 Figure 1-3. View of tank site from end of Fassler Avenue ..................................................................... 1-4 Figure 1-4. View of tank site from Estella Drive at Fassler Avenue ...................................................... 1-4 Figure 2-1. Alternative 1: Steel proposed section view ......................................................................... 2-2 Figure 2-2. Example bent plate roof system .......................................................................................... 2-2 Figure 2-3. Alternative 2: Concrete proposed section view ................................................................... 2-3 Figure 3-1. Steel tank alternative temporary grading ............................................................................ 3-3 Figure 3-2. Steel tank alternative finished grading ............................................................................... 3-4 Figure 3-3. Concrete tank alternative temporary grading ..................................................................... 3-5 Figure 3-4. Concrete tank alternative finished grading ......................................................................... 3-6 List of Tables Table 2-1. Proposed Tank Dimensions and Elevations Summary ........................................................ 2-3 Table 3-1. Tank Construction Quantities ................................................................................................ 3-1 Table 4-1. Estimate Markups .................................................................................................................. 4-1 Table 4-2. Construction Cost Estimate Summary .................................................................................. 4-4 Table 4-3. Capital Cost and NPV Summary ............................................................................................ 4-5 Table 5-1. Summary Comparison of Alternatives .................................................................................. 5-1 Fassler Tank Siting Study Table of Contents iv Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 List of Abbreviations BC Brown and Caldwell District North Coast County Water District ft foot/feet ft2 square foot/feet MG million gallons N/A not applicable NPV Net Present Value O&M Operations and maintenance OF Overflow SCADA supervisory control and data acquisition TM Technical Memorandum yd3 cubic yard(s) Fassler Tank Siting Study Table of Contents v Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. vi Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Executive Summary This technical memorandum (TM) summarizes findings and recommendations of a siting study for the North Coast County Water District’s (District) Fassler Tank Replacement Project. The proposed project includes replacing the existing welded steel tank with a new tank of 1.2 million gallons (MG) storage capacity along with associated valves, piping, power, supervisory control and data acquisition (SCADA) system and site improvements. The approach to the siting study considered placement of the proposed tank in relation to the property boundaries, recently mapped by the District’s surveyor, and the site’s challenging topography. A number of iterations were performed to optimize the placement and configuration of the tank alternatives, including temporary and finished grading and associated earthwork volumes. Brown and Caldwell’s (BC) structural team performed a foundation analysis for the steel alternative based on design criteria and recommendations from the geotechnical team and representatives from DN Tanks provided input on the proposed layout of the concrete alternative. The two alternatives were evaluated and compared based on several criteria including constructability, operation and maintenance (O&M), seismic performance, geotechnical considerations, and capital and lifecycle costs. Based on the findings in this TM, BC recommends the District proceed with detailed design and construction of a 1.2 MG, partially buried prestressed concrete tank at the Fassler site. The concrete option will result in a longer duration project, but overall provides a lower visual impact to the residents and very low maintenance costs over the life of the tank. The rising costs of steel since 2020 combined with the application of the Wasser coating system and substantial earthwork to build a larger steel tank into a hillside make the prestressed concrete tank more economical in the short and long-term. Fassler Tank Siting Study Executive Summary vii Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. 1-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 1 Introduction The Fassler tank is the District’s highest priority tank for replacement based on recommendations in the Potable Water Hydraulic Modeling Evaluation (EKI Environment & Water, Inc., March 2021). Brown and Caldwell (BC) was retained to evaluate replacement of the 500,000 gallon steel tank with a 1.2 million gallon (MG) steel or concrete tank with ultimate goal of identifying a preferred project to recommend for design. 1.1 Background Constructed in 1962, the current Fassler Tank is the highest tank in the southern portion of the system at an elevation of 709 feet (ft). Fassler Tank is a welded steel 0.5 MG tank (58 ft in diameter by approximately 27 ft high) and is supplied by Royce and Park Pacifica booster pump stations. The District has determined that Fassler Tank has reached the end of its useful life and requires replacement with a 1.2 MG capacity tank. Recently, Fassler tank was evaluated as part of the Fassler Tank Cost Evaluation (BC, 2021) which compared replacing Fassler with a 1.2 MG steel tank in its current location with a location adjacent to Frontierland Park at the same elevation. The evaluation concluded there was no clear benefit to relocating the tank; however, recommended that the District evaluate replacement of Fassler with a concrete alternative as a potential cost savings. The existing Fassler Tank is located at 1186 Fassler Avenue in Pacifica, California. The site is at the dead end of a service road off Fassler Avenue running parallel to Baquiano Hiking Trail. See the project location map in Figure 1-1. The property boundary is called out on the Project Site map, see Figure 1-2. The existing Bevco electrical building is located at the southwest corner of the site. Additionally, there is an existing cell tower located in the southeast corner of the site that could either be protected in place during construction or relocated by the lessee but would remain post construction of the replacement tank. The evaluation herein is based on March 2023 survey by LCC Engineering & Surveying. Fassler Tank Siting Study Section 1: Introduction 1-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Figure 1-1. Project location map Fassler Tank Siting Study Section 1: Introduction 1-3 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Figure 1-2. Project site map Visual impacts to neighboring residents are anticipated to be minor, as the trees screen the existing tank from view; however there is potential that the top of the replacement tank will be visible. Figure 1-3 is a photo taken from the closest residential neighborhood to the site, at the end of the paved portion of Fassler Avenue. Figure 1-4 is a photo taken at the corner of Estella Drive and Fassler Fassler Tank Siting Study Section 1: Introduction 1-4 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Avenue. The red boxes in both Figure 1-3 and Figure 1-4 are the approximate location of the existing Fassler Tank. Figure 1-3. View of tank site from end of Fassler Avenue Figure 1-4. View of tank site from Estella Drive at Fassler Avenue Although it is not in close proximity to neighboring residents, the current topography of the sloped site combined with the single entrance on the southeast corner of the site, any replacement project may create access challenges and increased construction traffic for the off-hauling of excess dirt. 2-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 2 Fassler Tank Alternatives The following section presents the various alternatives and criteria under which they are evaluated. The following Initial alternatives were identified considering material (steel vs. concrete) and depth of bury: • Alternative 1: Replace and upsize with welded steel • Alternative 2: Replace and upsize with prestressed concrete tank pushed into the uphill slope • Alternative 3: Replace and upsize with prestressed concrete partially buried tank and retaining wall to hold back the uphill slope After a preliminary discussion with DN Tanks, BC focused on one alternative for a prestressed concrete tank. This new alternative 2 is a hybrid of initial alternatives 2 and 3 above: partially buried and pushed into the uphill slope of the site. Thus, the alternatives evaluated in this Tank Siting Study include: • Alternative 1: Replace and upsize with welded steel • Alternative 2: Replace and upsize with prestressed concrete tank (partially buried and pushed into the uphill slope) Each alternative is also evaluated for the following: • Seismic performance • Constructability • Operation and maintenance (O&M) • Geotechnical considerations • Construction costs • Life cycle costs The capacity of 1.2 MG is set for each alternative, but dimensions may differ owing to some flexibility in operations of the proposed Fassler tank. Based on recent input from District staff, the proposed Fassler tank can operate with a water surface depth as low as 14 ft (Elevation 723) and as high as 28 ft from bottom (Elevation 737). 2.1 Alternative Details Alternative 1: Welded Steel Due to property boundary and topography constraints, the proposed steel tank presented is the largest diameter tank that would fit within the existing property given grading requirements. A structural evaluation was performed to size the steel tank alternative in accordance with American Waterworks Association Standard D100-11 for Welded Carbon Steel Tanks for Water Storage. Resulting dimensions for Alternative 1 are summarized in Table 2-1 and schematically illustrated in Figure 2-1. Additionally, this tank type has to be entirely above grade. Fassler Tank Siting Study Section 2: Fassler Tank Alternatives 2-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Figure 2-1. Alternative 1: Steel proposed section view This study assumes that this steel tank alternative would have an exterior bent plate roof. Typically, the rafters are the most difficult tank component to abrasive blast, coat and maintain and by selecting this style roof, the rafters would be relocated from the roof interior to the exterior of the tank. This results in a smooth surface on the underside of the roof with the rafters on the exterior where the service condition is less severe, leaving the coating system to protect the interior roof structure and the cathodic protection system to further protect the immersion zone. Figure 2-2 is an example of a steel tank exterior bent plate style roof. Figure 2-2. Example bent plate roof system Fassler Tank Siting Study Section 2: Fassler Tank Alternatives 2-3 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Alternative 2: Prestressed Concrete For the purposes of this evaluation, BC assumes a D113 Type 1 prestressed concrete tank with DN Tanks as the builder, similar to the District’s Sheila tank currently in construction. Thus, BC collaborated with DN tanks for preliminary tank sizing options for Alternative 2 based on the site constraints and capacity requirements. To reduce the visual impact, a flat roof design option (sloped for drainage) is selected. It is known that DN requires a 10 ft clearance from the tank outer wall to perform the prestressed bar wrapping. Due to the flexibility with which the District can operate Fassler tank, Alternative 2 is partially buried 7 ft with a bottom floor elevation of 703 ft. Resulting dimensions for Alternative 2 are summarized in Table 2-1 and illustrated in Figure 2-3. Figure 2-3. Alternative 2: Concrete proposed section view Table 2-1. Proposed Tank Dimensions and Elevations Summary Fassler Replacement Storage Tank Value (Elevation) Alternative 1a: Steel Alternative 2: Concrete Capacity, MGa 1.2 1.2 Tank floor elevation, ft (709.5) (703) Inside diameter, ft 86 80 Outside wall diameter, ft 86.5 82 Side water depth (OF elevation), ft 28 (737.5) 34 (737.0) Freeboard (above OF), ft 6 3.75 Total wall height, ft 34 (743.5) 37.75 (740.75) Knuckle, ft 3 N/A Roof rise, ft 2.7 2 Total structure height, ft 39.7 (748.7) 39.75 (742.75) Total exposed height above finished gradeb, ft 39.7 33.75 a. Tank dimensions assume bottom 6 inches of storage is unusable b. Finished Grade Elevation = 709 ft Fassler Tank Siting Study Section 2: Fassler Tank Alternatives 2-4 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. 3-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 3 Tank Evaluation BC evaluated two 1.2 MG tank alternatives for replacing the Fassler Tank; constructed of either welded steel (Alternative 1) or prestressed concrete (Alternative 2). The following sections summarize the evaluation completed for the tank alternatives. 3.1 Constructability BC reviewed constructability factors for the proposed alternatives, including construction duration and required earthwork. The following sections summarize these considerations. Both tanks are relatively straightforward to construct, with no unusual construction requirements. The estimated construction duration for the steel tank is approximately 4-5 months, compared to 6 to 9 months for the prestressed concrete tank. Both alternatives require a substantial amount of earthwork and will require use of the access road and residential streets to off-haul the excess dirt. BC developed preliminary layouts and completed a cut-and-fill analysis for the tank alternatives. Table 3-1 presents the net cut volume required for each option. Figures 3-1 and 3-3 illustrate the temporary grading plans for each alternative, while Figures 3-2 and 3-4 show the final grading plans. Table 3-1. Tank Construction Quantities Alternative Net Cut Volume (yd3) Retaining Wall Max Height Area (ft2) Alternative 1: Welded Steel 2,014 22’ 2,500 Alternative 2: Prestressed Concrete 4,240 N/A N/A yd3 = cubic yard(s) ft2 = square foot/feet The evaluation assumes the welded steel tank would be constructed at existing grade (elevation 709). As shown in Table 3-1, a temporary/permanent soil nail wall with maximum height of 22 ft will be required for the welded-steel tank alternative. The dimensions and placement of this alternative was selected based on the constraints of the property line and required grading for the soil nail wall. The owner of Associated Construction and Engineering, Inc. (a steel tank builder) reviewed the proposed layout from a constructability perspective and took no exceptions, as truck turnaround is not required for tank build. Substantial earthwork is required for the concrete tank alternative because it is partially buried to finished floor elevation of 703 ft and requires a 10 ft clearance for the prestressed wrap machine. However, no temporary retaining wall is required for Alternative 2 as the hill can withstand a 1:1 slope for the duration of construction to build the prestressed concrete tank alternative. A constructability team at DN Tanks reviewed the site for access and took no exceptions to the steep grades on the access road (max slope 16%). After construction, a finished grade elevation of 709 will be re-established and the prestressed concrete tank would serve as a permanent retaining wall for the uphill side. Fassler Tank Siting Study Section 3: Tank Evaluation 3-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Both scenarios assume that the resulting net cut volume of earthwork below will be hauled offsite by the Contractor. It is unknown whether the access road will need to be improved prior to construction. Thus, costs for improvement are not included in either alternative. The corrective deed describing the easement for this property, provided by the District and dated May 15, 2007 states that new construction and activities that would disturb vegetation or ground within the easement will require notification of and coordination with the National Park Service (NPS). Both alternatives involve grading within the easement and thus will require NPS coordination. Tree removal and restoration within the easement area has been included in the cost estimate. 86'-0" TANK PAD ELEV = 709 BOTTOM OF TEMP GRADING = 707 TANK WALL RETAINING WALL FOOTING 10'-0" 710 715 720 725 730 735 740 710 715 720 725 71 0 71 5 72 0 72 5 1. 0: 1 1.0:1 1.0:1 END OF RETAINING WALL FOOTING END OF RETAINING WALL FOOTING PLAN NORTH 0 1 2 SCALE = 1" = 30' Path: C:\bcpw\d2875218 Filename: 158938 Fig 3-1 StlTnk TG.dwg Plot Date: 9/1/2023 8:39 AM CADD User: Tait Lambert BC PROJECT NUMBER DESIGNED: CHECKED: DRAWN: FIGURE NUMBER 158938 ---- T. LAMBERT ---- STEEL TANK ALTERNATIVE TEMPORARY GRADING FIGURE 3-1 86'-0" TANK PAD ELEV = 709 TANK WALL RETAINING WALL 10'-0" 705 703 704 706 700 697 698 699 701 702 END OF RETAINING WALL FOOTING END OF RETAINING WALL FOOTING MAX HEIGHT OF RETAINING WALL = 22'-0" EXTENT OF SOIL NAIL WALL, WALL HEIGHT > 10'-0" 708 708 ELEV = 708.5 ELEV = 707 EXTENT OF SOIL NAIL WALL PLAN NORTH 0 1 2 SCALE = 1" = 20' Path: C:\bcpw\d2875218 Filename: 158938 Fig 3-2 StlTnk FG.dwg Plot Date: 8/11/2023 10:15 AM CADD User: Tait Lambert BC PROJECT NUMBER DESIGNED: CHECKED: DRAWN: FIGURE NUMBER 158938 ---- T. LAMBERT ---- STEEL TANK ALTERNATIVE FINISHED GRADING FIGURE 3-2 1. 0: 1 1.0:1 1.0:1 1. 0: 1 1.0:1 705 710 715 720 725 730 705 710 715 720 725 730 735 740 705 710 715 720 705 70 571 0 10'-0" CLR Path: C:\bcpw\d2875218 Filename: 158938 Fig 3-3 ConcTnk TG.dwg Plot Date: 9/15/2023 4:32 PM CADD User: Tait Lambert BC PROJECT NUMBER DESIGNED: CHECKED: DRAWN: FIGURE NUMBER 158938 ---- T. LAMBERT ---- CONCRETE TANK ALTERNATIVE TEMPORARY GRADING FIGURE 3-3 PLAN NORTH 0 1 2 SCALE = 1" = 20' ELEV = 702 80'-0" FINISHED FLOOR ELEV = 703 BOTTOM OF TEMP GRADING = 702 2. 0: 1 2. 0: 1 2.0:1 2.0:1 720 725 730 735 720 725 730 735 740 745 Path: C:\bcpw\d2875218 Filename: 158938 Fig 3-4 ConcTnk FG.dwg Plot Date: 8/11/2023 9:51 AM CADD User: Tait Lambert BC PROJECT NUMBER DESIGNED: CHECKED: DRAWN: FIGURE NUMBER 158938 ---- T. LAMBERT ---- CONCRETE TANK ALTERNATIVE FINISHED GRADING FIGURE 3-4 PLAN NORTH 0 1 2 SCALE = 1" = 20' ELEV = 709 80'-0" FINISHED FLOOR ELEV = 703 Fassler Tank Siting Study Section 3: Tank Evaluation 3-7 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 3.2 Seismic Performance Seismic performance was considered in this evaluation for both steel and prestressed concrete tanks. Both tank types are required to be designed for loads determined in accordance with ASCE 7. Under ASCE 7, both types of tanks are to be designed for the same design earthquake for a particular site. Since both tank types are designed using current state of the art design principles for each type of material, and for the same design earthquake event, it is anticipated that both tanks will perform as designed in the event of seismic activity, meaning there is no advantage to either material based on seismic performance. 3.3 Operation and Maintenance O&M will differ depending on the selected tank material. The following sections present O&M considerations for welded-steel and prestressed concrete tank options. For either material, the District would inspect on a 5 to 10 year cycle using divers for the interior inspection while the tank is filled. Typically, the District would have the divers vacuum the tank bottom about every 10 years since tanks accumulate fine inert sediment even when filled with very low turbidity potable water. Should a major nearby seismic event occur, the District likely would carry out a specialty interior inspection. Alternative 1: Welded Steel Future steel tank maintenance includes an interior and external coating for corrosion, and internal inspections and cleanings. The coastal climate of this site will increase the rate of corrosion with a steel tank alternative. Based on the District’s experience, the Wasser Coating system is preferred as it performs well in cold, coastal environments. The system includes a moisture cured polyurethane zinc rich primer (MC Zinc 100) followed by a moisture cured polyurethane intermediate coat (MC Mio Mastic 100) followed by an aliphatic polyurethane topcoat (MC Luster 100). Additionally, Wasser products will cure at low temperatures. If the coatings are applied within the recommended film thickness ranges, a welded-steel tank at this site would need exterior recoating about every 20 years. Interior recoating would occur on the same interval, about every 20 years. The protective coating should be applied under the following techniques for the best results: 1. The welded seams are ground until smooth, then the surface area of the tank is abrasive-blasted per Society for Protective Coatings standards. 2. After surface preparation, the contractor applies the new liquid coating either using sprayers or rollers. 3. The coating then air dries and cures. For the interior, an internal coating system (ICS #5) is recommended and includes a zinc rich primer, an epoxy intermediate coat, and epoxy topcoat. Additionally, to further protect the internal coating system, replacement of the cathodic protection system at each recoating interval is recommended. Alternative 2: Prestressed Concrete Prestressed concrete tanks do not require any coatings, interior or exterior, for corrosion control. Any coating of a concrete tank is solely for aesthetic purposes, such as painting the tank to blend into the surrounding landscape. To be consistent with Sheila tank, a coating is assumed to be not necessary for the concrete tank alternative. While the Fassler tank may not generally visible to any Fassler Tank Siting Study Section 3: Tank Evaluation 3-8 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 nearby residents, many people frequent the nearby Baquiano Hiking Trail and regularly pass by the tank; thus, power washing approximately every 10 years is good practice to keep the exterior clean. 3.4 Geotechnical Considerations The proposed site is geotechnically suitable for the project. The design should incorporate appropriate seismic, foundation, and retaining structure design to accommodate geotechnical conditions. The tank design will call for the use of appropriate seismic design factors, which can be found in Table C of the Geotechnical Investigation Report by Miller Pacific Engineering Group dated August 1, 2023 (Appendix A). The tank will have to utilize a shallow foundation due to the relatively shallow depth of weathered bedrock at the site. However, the foundation footings should be deepened to reduce the potential for differential settlement. For the steel tank alternative, taller retaining walls over 10 ft in height should consist of shotcrete- faced walls supported with soil-nails or rock anchors where cuts are planned. The required length of soil nails for higher walls should be checked against the property boundaries. Conventional cast-in- place reinforced concrete walls could also be used, however; these would require even more grading. Upslope retaining structures are also recommended to reduce the required amount of grading above the tank as well as the off-haul and disposal of material. For a geotechnical standpoint, embedding the concrete tank alternative deeper is beneficial and would have uniform support on the weathered bedrock throughout the footprint. Harder rock may be encountered and should be defined in the contract documents and a line item bid for a small amount of rock excavation. Temporary cut slopes with a slope of 1:1 will be required during construction until either retaining walls can be constructed and backfilled, or the tank itself can be backfilled at no more than an 8 ft differential from the uphill to downhill sides. Permanent backfill slopes should be no steeper than 2:1. 4-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 4 Preliminary Cost Estimates BC developed Class 5 cost estimates for the alternatives in accordance with Association for the Advancement of Cost Engineering International (AACE). A Class 5 estimate is defined as a Conceptual Level or Project Viability Estimate. Typically, engineering is from 0 to 2 percent complete. Class 5 estimates are used to prepare planning level cost scopes or evaluation of alternative schemes, long range capital outlay planning and can also form the base work for the Class 4 Planning Level or Design Technical Feasibility Estimate. Expected accuracy for Class 5 estimates typically ranges from -50 to +100 percent, depending on the technological complexity of the project, appropriate reference information and the inclusion of an appropriate contingency determination. In unusual circumstances, ranges could exceed those shown. The high contingency costs associated with a Class 5 estimate represent the undeveloped design; the design team will refine and reduce the contingency as the project design advances. BC assumed a 50 percent contingency for both tank alternatives. The estimated costs presented in the following sections are current for Northern California summer 2023 construction and assume an allowance for escalation to the construction mid-point: winter 2024. Cost estimates developed for future design phases when the construction schedule is more firmly established will further adjust cost escalation for inflation. 4.1 Estimated Construction Costs for Tank Alternatives BC calculated construction costs for all three alternatives. Table 4-1 presents assumptions for developing construction and capital costs. Table 4-1. Estimate Markups Item Value Contingency (%) 50 Accuracy range (5%) -50 to +100 Overhead and profit (%) 10 Sales tax (%) 9.875 Insurance (%) 2 Bond (%) 1.5 Escalation (%) 8/year to midpoint of construction Net Present Value (NPV) term (years) 60 Fassler Tank Siting Study Section 4: Preliminary Cost Estimates 4-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Overhead and Profit Capped at 10% this covers payroll and accounting, estimator’s wages, home office rent, advertising and owner profit. Sales Tax This is the tax that the contractor must pay according to state and local tax laws. The percentage is applied to both the material and equipment the general contractor purchases as well as the cost for rental equipment. The percentage is based on the local rates in place at the time the estimate was prepared. Insurance This percentage comprises builders risk, liability, and vehicle insurance. There are many factors which make up this percentage, including the contractor’s track record for claims in each of the categories. Another factor affecting insurance rates has been a dramatic price increase across the country over the past several years due to domestic and foreign influences. Consequently, in the construction industry we have observed a range of 0.5 to 1 percent for Builders Risk Insurance, 1 to 1.25 percent for General Liability Insurance, and 0.85 to 1 percent for Vehicle Insurance. Many factors affect each area of insurance, including project complexity and contractor’s requirements and history. Instead of using numbers from a select few contractors, BC believes it is more prudent to use a combined 2 percent to better reflect the general costs across the country. Consequently, the actual cost could be higher or lower based on the bidder, region, insurance climate, and the contractor’s insurability at the time the project is bid. Bond Based on historical and industry data, this can range from 0.75 to 3 percent of the project total. There are several contributing factors including such items as size of the project, regional costs, contractor’s historical record on similar projects, complexity and current bonding limits. BC uses 1.5 percent for bonds, which we have determined to be reasonable for most heavy construction projects. Escalation In addition to contingency, it is customary for projects that will be built over several years to include an escalation to midpoint of anticipated construction to account for the future escalation of labor, material and equipment costs beyond values at the time the estimate is prepared. For this project, the anticipated rate of escalation is 8 percent per annum, and is assumed to be bid in 2024. 4.1.1 Estimate Assumptions As the design progresses through different completion stages, it is typical for the estimator to make assumptions to account for details that may not be evident from the documents. The following assumptions were used in the development of this estimate and apply to both Alternative 1 and 2. 1. The tank vendor quotes are located near the bottom of the estimate totals page to avoid adding the overhead, profit and contingencies markups to the tank cost. 2. The estimate includes an 8 percent annual markup for construction beyond 2023. 3. Site work includes onsite pavement replacement. 4. The existing cell tower onsite will remain and be protected in place during construction. 5. The electrical prices are the same for both alternatives. Fassler Tank Siting Study Section 4: Preliminary Cost Estimates 4-3 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 4.1.2 Alternative Specific Estimating Assumptions The following assumptions are specific to each alternative evaluated. Alternative 1: Steel BC has developed a construction cost estimate for a welded steel tank based on the following assumptions: 1. The tank will have an external bent rafter roof style. 2. The tank will be at-grade with an 8 ft-wide temporary and permanent access path. 3. The new tank will be painted on the exterior walls. 4. The vendor quote for tank coating is located near the end of the totals page of the estimate. This was done to avoid adding the overhead, profit, and contingencies markups to the tank cost. The tank coating quote is based on the Wasser system for the exterior and Tnemec system for the interior coating (meeting ICS #5 standards). 5. The permanent retaining wall will be a soil nail wall. 6. An allowance is included for replacing the existing vaults, valves, and site piping. 7. Deep foundation (i.e., piles or piers), horizontal slab extension, or keyway is not included. If required due to additional information provided by the geotechnical engineer, this budget will need to be re-evaluated. Alternative 2: Concrete BC has developed a construction cost estimate for a prestressed concrete tank based on the budgetary estimate letter dated July 27, 2023 by DN Tanks (Appendix B) and the following assumptions: 1. The tank will be uniformly backfilled. 2. No soil or excessive live loads are present on the tank roof. 3. The roof will be a free-spanning concrete low profile (flat) roof. 4. The bottom elevation of the tank will be partially below grade and pushed into the hillside. 5. No temporary retaining wall will be required during construction, and the tank wall will serve as a permanent retaining wall following construction. A 10 ft path around the tank will be needed during construction. 6. An allowance is included for replacing the existing vaults, valves, and site piping. 7. Deep foundation (i.e., piles or piers), horizontal slab extension, or keyway are not included If required due to additional information provided by the geotechnical engineer, this budget will need to be re-evaluated. 8. The DN Tanks quote has the following exclusions which are inclusions to this estimate: The figures above exclude site work, subgrade preparation, baffle walls, all piping and mechanical equipment, electrical, instrumentation, and SCADA. 4.1.3 Estimating Exclusions The following are not included in this estimate. 1. Different or unusual site materials/subsurface conditions particularly as it relates to upslope areas impacted by temporary excavation. 2. Hazardous materials remediation and/or disposal. 3. Client O&M and labor costs for the project. Fassler Tank Siting Study Section 4: Preliminary Cost Estimates 4-4 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 4. Utility agency costs for incoming power modifications. 5. Relocation of cell site utilities. 6. Permits beyond those normally needed for the type of project and project conditions. 7. Impacts from COVID-19 including additional labor and management hours required to meet social distancing, personal protection, and cleaning routines, additional costs of protective equipment, supply chain impacts, and material shortages. 8. Dewatering. 9. Temporary facilities to maintain NCCWD system operations, including temporary storage tanks and piping. 4.1.4 Construction Cost Summary Table 4-2 summarizes the cost estimates for the tank alternatives. Table 4-2. Construction Cost Estimate Summary Item Value Alternative 1: Steel Alternative 2: Concrete Mobilization/demobilization $250,000 $130,000 Earthwork $238,000 $528,000 Sitework and demo $720,000 a $110,000 Allowance for utilities and appurtenancesb $189,000 $222,000 Electrical and instrumentation $290,000 $290,000 Contractor Subtotal before contingency and markups $1,690,000 $1,280,000 Contingency (50%) $840,000 $640,000 Contractor Subtotal before markups $2,530,000 $1,920,000 Overhead and tax markups $378,000 $287,000 Tank $1,200,000 $2,500,000 Tank coatingc/painting $914,000 $150,000 Insurance, bond, and escalation markups $1,200,000 $1,160,000 Grand Total $6,223,000 $6,020,000 AACE Class 5 accuracy range (-30 to +50%) $4,350,000-$9,330,000 $4,210,000-$9,090,000 Cost per gallon ($/gallon), (-30 to +50%) $3.63-$7.78 $3.50-$7.57 a. The sitework and demo cost for alternative 1 is higher than for alternative 2 due to the cost of the retaining wall and tank foundation needed for this alternative. b. Allowance for appurtenances include handrails, exterior and interior ladder, roof equipment/access hatch, vents, additional roof sleeves, sample taps, additional hatches, piping, and mechanical equipment. c. This is the cost of the initial interior and exterior tank coating during construction. Note that a welded steel tank would likely need exterior and interior recoating every 20 years. Fassler Tank Siting Study Section 4: Preliminary Cost Estimates 4-5 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 4.2 Life Cycle Cost Analysis BC developed life-cycle costs for the two tank alternatives, considering both capital costs and recoating costs. Table 4-3 presents the capital cost and NPV. Appendix C presents detailed construction cost estimates and NPV calculations. Table 4-3. Capital Cost and NPV Summary Item Alternative 1: Steel Alternative 2: Concrete Construction cost $6.2M $6.0M Engineering/permitting/administration/CM $1.4M $1.4M Capital cost $7.6M $7.4M Recoating cost (20-year interval) $1.4M N/A NPV (60-year LCC) $13.8M $7.4M The NPV assumes that the prestressed concrete tank alternative will have an exterior paint applied. Repainting of the prestressed concrete over the life of the tank will be required, but the effort is not comparable to a performance recoating of a steel tank ($100,000 vs $1 million). Thus, repainting costs for the prestressed concrete tank are not included and it is assumed that the NPV for the prestressed concrete tank is equal to the capital cost. Other maintenance costs (e.g., exterior pressure washing and periodic vacuum sediment removal) are not considered in the NPV calculation. Fassler Tank Siting Study Section 4: Preliminary Cost Estimates 4-6 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. 5-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 5 Findings and Recommendations The following sections include the siting study conclusions and recommendations for future Fassler Tank replacement design. 5.1 Comparison of Alternatives Relative comparisons between each alternative have been evaluated with respect to seismic performance, constructability, O&M, geotechnical considerations, construction cost estimate and life cycle cost analysis are summarized in Table 5-1. Table 5-1. Summary Comparison of Alternatives Criteria Alternative 1: Steel Alternative 2: Concrete Seismic performance + + Constructability + - O&M - + Geotechnical considerations - + Construction cost estimate - + Life cycle cost analysis - + The advantages and disadvantages of both alternatives are listed below: Alternative 1: Steel Advantages: • Shorter construction duration • Less earthwork and less off-haul material • Smaller construction footprint, potentially less impact to the community Disadvantages: • Higher capital/maintenance costs (i.e. tank recoating every 20 years) • Permanent retaining wall, higher design costs • Taller tank and greater visual impact Alternative 2: Concrete Advantages: • Lower capital/maintenance costs • Partially buried tank, lower visual impact • No retaining wall required for construction Fassler Tank Siting Study Section 5: Findings and Recommendations 5-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Disadvantages: • Significant earthwork and off-hauling of excess material • Longer construction duration Based on the evaluation presented herein, BC recommends the District proceed with detailed design and construction of a 1.2 MG, partially buried prestressed concrete tank at the Fassler site. The concrete option will result in a longer duration project, but overall provides a lower visual impact to the residents and very low maintenance costs over the life of the tank. The rising costs of steel since 2020 combined with the application of the Wasser coating system and substantial earthwork involved in building a larger steel tank into a hillside make the prestressed concrete tank more economical in the short and long-term. Prior to design, it is recommended to conduct additional site investigations including: • Tree survey • Additional geotechnical borings across the site • All discharge points located (drain, overflow, storm drain) • NPS mitigation requirements 6-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 6 Limitations This document was prepared solely for North Coast County Water District in accordance with professional standards at the time the services were performed and in accordance with the contract between North Coast County Water District and Brown and Caldwell dated September 2, 2022. This document is governed by the specific scope of work authorized by North Coast County Water District; it is not intended to be relied upon by any other party except for regulatory authorities contemplated by the scope of work. We have relied on information or instructions provided by North Coast County Water District and other parties and, unless otherwise expressly indicated, have made no independent investigation as to the validity, completeness, or accuracy of such information. Fassler Tank Siting Study Section 6: Limitations 6-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. 7-1 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Section 7 References Brown and Caldwell, Fassler Tank Evaluation, 2021 EKI Environment & Water, Inc., Potable Water Hydraulic Modeling Evaluation, March 2021 Fassler Tank Siting Study Section 7: References 7-2 Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. Fassler Tank Siting Study A Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 Appendix A: Geotechnical Report Fassler Tank Siting Study Appendix A A Use of contents on this sheet is subject to the limitations specified at the end of this document. Fassier Siting Study Final 092823 This page intentionally left blank. Mailing Address:  Phone Number: (415) 382-3444  Physical Address: P.O. Box 2802  Fax Number: (415) 382-3450  504 Redwood Blvd., Suite 220 Novato, California 94948-2802 Novato, California 94947 GEOTECHNICAL INVESTIGATION NORTH COAST COUNTY WATER DISTRICT FASSLER TANK REPLACEMENT PROJECT PACIFICA, CALIFORNIA August 1, 2023 Project 2281.002 Prepared For: North Coast County Water District c.o. Brown and Caldwell 201 North Civic Drive, Suite 300 Walnut Creek, California 94596 Attn: Ms. Davina Carboni CERTIFICATION This document is an instrument of service, prepared by or under the direction of the undersigned professionals, in accordance with the current ordinary standard of care. The service specifically excludes the investigation of radon, asbestos, toxic mold and other biological pollutants, and other hazardous materials. The document is for the sole use of the client and consultants on this project. Use by third parties or others is expressly prohibited without written permission. If the project changes, or more than two years have passed since issuance of this report, the findings and recommendations must be reviewed by the undersigned. MILLER PACIFIC ENGINEERING GROUP REVIEWED BY: (a California corporation) Emily Carreno Scott Stephens Staff Geologist Geotechnical Engineer 2398 (Expires 6/30/25) GEOTECHNICAL INVESTIGATION NORTH COAST COUNTY WATER DISTRICT FASSLER TANK REPLACEMENT PROJECT PACIFICA, CALIFORNIA TABLE OF CONTENTS 1.0 INTRODUCTION ................................................................................................................ 1 2.0 PROJECT DESCRIPTION ................................................................................................. 1 3.0 SITE CONDITIONS ............................................................................................................ 1 3.1 Regional Geology ........................................................................................................... 1 3.2 Surface Conditions ......................................................................................................... 2 3.3 Field Exploration and Laboratory Testing ....................................................................... 2 3.4 Subsurface Conditions ................................................................................................... 2 3.5 Groundwater .................................................................................................................. 2 3.6 Seismicity ....................................................................................................................... 3 3.6.1 Active Faults in the Region ...................................................................................... 3 3.6.2 Historic Fault Activity ............................................................................................... 3 3.6.3 Probability of Future Earthquakes ........................................................................... 3 4.0 GEOLOGIC HAZARDS EVALUATION ............................................................................. 4 4.1 Fault Surface Rupture .................................................................................................... 4 4.2 Seismic Shaking ............................................................................................................. 4 4.3 Landsliding and Slope Stability ...................................................................................... 6 4.4 Liquefaction Potential and Related Impacts ................................................................... 7 4.5 Seismic Induced Ground Settlement .............................................................................. 7 4.6 Lurching and Ground Cracking ...................................................................................... 7 4.7 Erosion ........................................................................................................................... 7 4.8 Seiche and Tsunami....................................................................................................... 8 4.9 Expansive Soils .............................................................................................................. 8 4.10 Settlement/Subsidence .................................................................................................. 8 4.11 Flooding ......................................................................................................................... 8 5.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................. 9 5.1 Conclusions .................................................................................................................... 9 5.2 Seismic Design .............................................................................................................. 9 5.3 Site Grading ................................................................................................................... 9 5.3.1 Surface Preparation .............................................................................................. 10 5.3.2 Excavations ........................................................................................................... 10 5.3.3 Materials ................................................................................................................ 11 5.3.4 Compacted Fill ...................................................................................................... 11 5.3.5 Permanent and Temporary Cut Slopes ................................................................. 11 5.4 Foundation Design ....................................................................................................... 12 5.5 Retaining Wall Design .................................................................................................. 13 5.6 Concrete Slabs-on-Grade ............................................................................................ 14 5.7 Underground Utilities .................................................................................................... 15 5.8 Site Drainage and Erosion Control ............................................................................... 15 5.9 Pavements ................................................................................................................... 15 6.0 LIMITATIONS .................................................................................................................. 16 7.0 SUPPLEMENTAL GEOTECHNICAL SERVICES ........................................................... 16 8.0 LIST OF REFERENCES .................................................................................................. 17