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HomeMy WebLinkAbout07. Amend a consultant agreement and approve the Phase 2-Aeration Basins Diffuser Replacement Project Page 1 of 5 Item 7. CENTRAL SAN BOARD OF DIRECTORS POSITION PAPER MEETING DATE: MAY 6, 2021 SUBJECT: APPROVE PHASE 2 -AERATION BASINS DIFFUSER REPLACEMENTAND SEISMIC UPGRADES PROJECT IN THE FISCAL YEAR 2020-2021 BUDGET AND FUNDING FROM THE STEAMAND AERATION BLOWER SYSTEMS RENOVATIONS, DISTRICT PROJECT 7349; FIND THE PROJECT IS EXEMPT FROM THE CALIFORNIA ENVIRONMENTAL QUALITYACT; AND AUTHORIZE THE GENERAL MANAGER TO AMEND AN EXISTING AGREEMENT WITH HDR, INC. TO INCLUDE FINAL DESIGN SERVICES IN AN AMOUNT NOT TO EXCEED $1,856,000, INCREASING THE COST CEILING TO $5,326,000 SUBMITTED BY: INITIATING DEPARTMENT: NITIN GOEL, SENIOR ENGINEER ENGINEERING AND TECHNICAL SERVICES- PDS-ASSET MANAGEMENT REVIEWED BY: DANEA GEMMELL, PLANNING AND DEVELOPMENT SERVICES DIVISION MANAGER EDGAR J. LOPEZ, CAPITAL PROJECTS DIVISION MANAGER JEAN-MARC PETIT, DIRECTOR OF ENGINEERING AND TECHNICAL SERVICES STEVE MCDONALD, DIRECTOR OF OPERATIONS Roger S. Bailey General Manager ISSUE The Board of Directors (Board) authorization is required for the General Manager to amend an existing professional engineering services agreement in an amount greater than $200,000. May 6, 2021 Regular Board Meeting Agenda Packet- Page 36 of 239 Page 2 of 5 BACKGROUND Recently, the existing aeration system has not been able to reliably maintain a desired dissolved oxygen levels across the basins. Proper oxygen transfer is an essential element of a biological activated sludge treatment process. This has contributed to a steady deterioration (increase) in sludge volume index(SVI), which is a key secondary process operational parameter for activated sludge settleability and compaction. The increase in the SV I has in turn, led to concerns over the ability to consistently meet National Pollutant Discharge Elimination System (NPDES) discharge limitations. While Central San continues to meet NPDES discharge permit limits, further deterioration in performance of the aeration system will cause more challenges over time, which would also lead to poor settleability in the secondary clarifiers and would impact the performance of the UV disinfection system. Staff updated the Board and Engineering and Operations (E&O) Committee at several meetings, including on December 20, 2018, when authorization was granted to enter into an agreement with HDR, I nc. (HDR) for the condition assessment and preliminary design of the Steam and Aeration Blower Systems Renovations, District Project(DP) 7349 (Steam Project). This decision was made after a very competitive and formal solicitation process and selection that included four qualified consulting engineering firms. At the Board Meeting on July 16,2020, staff proposed phasing the design of the Steam Project into multiple projects. The Board also approved the first phase of the project- Electric Blower Improvements, DP 7377 (now DP 10015). Based on detailed evaluations, completed as part of the Steam Project on the aeration system and structural integrity of the aeration basins, as well as operational reliability concerns, staff now recommends proceeding with the final design of Phase 2 -Aeration Basins Diffuser Replacement and Seismic Upgrades (Aeration Project). Summary A detailed condition assessment was completed as part of the Steam Project that evaluated the condition of the aeration system (diffusers and other associated mechanical assets) and the structural integrity of the aeration basins, with an emphasis on meeting current seismic code. The condition assessment and comprehensive asset evaluations recommend diffuser replacement, mechanical asset rehabilitation/replacement, controls upgrade, concrete repairs, and structural improvements to prolong the remaining useful life of the aeration basins and improve resiliency. Aeration Basin Diffusers Based on the Steam Project condition assessment task, the existing diffusers are from the early 1970s, are reaching the end of their useful life, and require replacement. The four aeration basins contain 9,600 ceramic fine bubble diffusers located in plenum boxes on the basin floor. Diffusers convert air from air distribution piping into fine bubbles to provide oxygen to activated sludge bacteria. In 2009 and 2010 during the Aeration Air Renovations, DP 7207 and Aeration Air Renovations - Phase 2, DP 7274, plenum grout injection was completed to seal cracks and reduce air leaks, 15 percent of diffusers were replaced in-kind (1,440), new actuators valves were installed, new pressure relief valves were installed, and other miscellaneous repairs were completed.After many years of service and based on the evaluations described below, replacing only the non-functional diffusers would still very likely continue to pose risk due to fouling and porosity differences between new and older diffusers as seen from the last replacement. Diffusers and Mechanical Assets Condition Assessment Findings Based on evaluations of the diffusers in two of the four basins, an estimated 50 percent of diffusers are non-functional due to fouling/clogging attributed to the number of years in service. Basin gates and downcomers require rehabilitation or replacement due to corrosion. The concrete structures are in fair condition with some locations requiring surface repairs. Seismic Evaluation Findings There are structural evaluation standards for existing structures and tanks or the 1970s aeration basins developed to assess the seismic vulnerability of aged infrastructure and these standards were developed May 6, 2021 Regular Board Meeting Agenda Packet- Page 37 of 239 Page 3 of 5 from lessons learned based on structural damage and behavior after major earthquakes, such as Loma Prieta in 1989 and Northridge in 1994. The previous codes designed for lower-than-expected ground shaking incorporate insufficient member ductility to remain undamaged after an earthquake. HDR completed a seismic evaluation using the 2019 California Building Code and California Existing Building Code, which references American Society of Civil Engineers (ASCE)41 for Existing Building Design. Structural analysis identified a need to strengthen overstressed walls and beams and repair expansion joints to wall connections. Diffusers Performance Testing Findings The existing aeration system performance has deteriorated over time. The oxygen transfer efficiency of the diffusers is 0.3 percent per feet, which is much lower than typical values observed at conventional activated sludge treatment plants of 0.6 to 1.1 percent per feet. Professor Michael Stenstrom from UCLA performed the oxygen transfer efficiency testing of the existing diffusers in 2019 (as a part of Steam Project), as well as in 1997, and 1991 as part of past projects. He found that the diffuser performance in 2019 has deteriorated significantly compared to the past diffuser performance. Staff prepared a business case evaluation (BCE) comparing replacing existing ceramic diffusers in-kind and repairing the plenum versus installing new membrane diffusers without the plenum. Staff concluded that the replacement with the latest technology membrane type diffusers without the plenum was preferable as the long-term solution. The BCE was based on capital cost, net present worth cost, as well as cost benefit ratio. Operational Concerns with Secondary Process and Permit Impacts Due to the large number of manual control valves and non-functional diffusers, required air flow distribution to maintain the desired oxygen transfer for the activated sludge process across the basin is challenging to maintain.As a result, the existing aeration system is not able to maintain a desired dissolved oxygen levels across the basin. This has contributed to a steady deterioration in settleability illustrated by an increase in the SVI and has increased concerns by operational staff over the ability to reliably meet NPDES discharge limitations in the future. Government Code Section 1090 (Section 1090) Compliance: HDR will be performing the technical work for the final design of Aeration Project, which is in compliance with Section 1090. HDR has not been precluded from continuing with the final design of the Aeration Project and associated potential subsequent engineering services during construction of the elements identified as part of the Aeration Project and other phases of the Steam Project based on the following premises: 1. The publicly advertise scope of the Steam Project for consultant selection included from its inception elements for the Aeration Project, related work as well as other phases; 2. HDR role and scope on the project during the preliminary design, BCE, and assessments were limited to technical evaluations in nature only and did not include any recommendations independent from staff; 3. HDR was not acting in a capacity similar to that of a Central San employee or staff; 4. HDR did not perform work that independently defined the scope of the subsequent contract amendments; 5. HDR did not influence the decision making of Central San regarding the subsequent work; and 6. Board Committee meetings and Board presentations were prepared, presented, and recommendations created by Central San staff. The elements identified as part of the Steam Project will be implemented in Phases: • Phase 1: New Electric Blowers - DP 10015 (Currently in Final Design) • Phase 2: Aeration Project • Phase 3: Secondary System Improvements • Phase 4: Steam System and Existing Aeration Blower Renovations May 6, 2021 Regular Board Meeting Agenda Packet- Page 38 of 239 Page 4 of 5 The major elements of the scope of the Aeration Project is described below: The Aeration Project will develop the final design drawings and specification for structural upgrades, mechanical assets rehabilitation/replacement, concrete repairs, diffuser system replacement or upgrades, demolishing the existing air plenums, and installation of with state of industry systems such as membranes. This project will also be replacing some of the air piping, reconfigure the aeration basins (a.k.a. A/N Tanks)to maximize the use of unused channels to optimize the activated sludge process using available volume and tankages, as well as implementing instrumentation and controls upgrades to improve air flow distribution to match process oxygen demands. California Environmental Quality Act (CEQA) Staff has concluded that the project is exempt from CEQA under Central San's CEQA Guidelines Section 15301, since it involves repairs, maintenance and minor alterations to an existing sewage facility with no increase in capacity; and Section 15302, since it involves replacement of existing public facilities at the same location and with the same purpose. Any capacity increases are for non-growth inducing, wet weather purposes. Approval of this project will establish the Board's independent finding that this Project is exempt from CEQA. ALTERNATIVES/CONSIDERATIONS Alternative 1: Status Quo - Do Nothing Alternative, replacement in-kind of only non-functional diffusers (-50 percent of existing diffusers) overtime during preventative maintenance shutdowns. Replacing only non-functional diffusers is considered high-risk due to fouling and porosity differences between new and existing diffusers that may result in compatibility issues. Alternative 2: Exclude some elements of the project, such as the mechanical rehabilitation/replacement, controls upgrade, concrete repairs, or structural improvements. The mechanical replacement, diffusers, and the concrete repairs are needed immediately. Seismic upgrades should be completed during the renovation of the diffuser system and the demolition of the air plenums. Performing the seismic upgrades later would be more expensive and most likely result in re-doing the mechanical systems. These alternatives are not recommended. FINANCIAL IMPACTS The total anticipated cost for the final design of the Aeration Project is $1,056,000, which includes bidding services. The current cost ceiling of HDR's Steam Project agreement is $3,470,000. If the Board approves the additional $1,856,000, this will result in a new HDR contract value or cost ceiling of $5,326,000, as shown in the table below. Services Fees Board Approval Original Agreement with HDR for Steam Project $2,590,000 December 20, 2018 Phase 1 - Electric Blower Improvements DP $880,000 July 16, 2020 10015 - Final Design and Bidding Services Current HDR Agreement $3,470,000 Phase 2 -Aeration Basins Diffuser Replacement & Seismic Upgrades Project- Final Design and $1,856,000 Bidding Services Total Contract Value with Amendment $5,326,000 There are adequate funds within the current budget of the Steam Project, DP 7349 to fund the Aeration May 6, 2021 Regular Board Meeting Agenda Packet- Page 39 of 239 Page 5 of 5 Project- Final Design and Bidding Services. The total estimated construction cost is $22,900,000, which equates to roughly 8.1 percent of the design fee for HDR. A future amendment to the agreement is anticipated if the Phase 2 project is awarded for construction. COMMITTEE RECOMMENDATION The Engineering and Operations Committee reviewed this matter at its meeting on April 20, 2021 and recommended approval. RECOMMENDED BOARD ACTION Staff recommends the following: 1. Find that the Project is exempt from CEQA; 2. Approve Phase 2 -Aeration Basins Diffuser Replacement and Seismic Upgrades Project in the Fiscal Year 2020-21 Budget and funding from the Steam and Aeration Blower Systems Renovations, District Project 7349; and 3. Authorize the General Manager to amend an existing professional engineering services agreement with HDR, Inc. to include final design for Phase 2 -Aeration Basins Diffuser Replacement and Seismic Upgrades Project in an amount not to exceed $1,856,000, increasing the agreement cost ceiling to $5,326,000. Strategic Plan re-In GOAL TWO: Environmental Stewardship Strategy 1—Achieve 100% compliance in all regulations, Strategy 2—Anticipate and prepare for potential regulatory changes GOAL FIVE: Infrastructure Reliability Strategy 1—Manage assets optimally to prolong their useful life, Strategy 2—Execute long-term capital renewal and replacement program GOAL SIX: Innovation and Optimization Strategy 1—Implement the Central San Smart Initiative, Strategy 2—Improve and modernize operations through technology and efficiency measures May 6, 2021 Regular Board Meeting Agenda Packet- Page 40 of 239