Agda Pkt 2025.03.10 Joint SA PFA

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Page 2 of 5 City of Redwood City 1017 Middlefield Road, Redwood City, CA. 94063 Tel: 650-780-7000 www.redwoodcity.org On December 21, 2021, Public Works staff identified a sinkhole near the County of San Mateo’s metering station at 1513 Veterans Boulevard. Upon investigation, it was discovered that the sinkhole resulted from a collapse in the 30-inch north sanitary sewer main. The collapsed main prompted a thorough condition assessment of the north and south sanitary sewer lines. In 2022, emergency work was performed to replace the existing sanitary sewer main connecting the north and south lines, labeled “Emergency Work 2022” in Figure 1 in the Analysis Section, below. In March 2023, Public Works staff noticed cracks along the road surface at the intersection of Veterans Boulevard and Chestnut Street, indicating damage to the 33-inch south sewer main. A CCTV condition assessment confirmed both the north and south sanitary sewer lines were in failing condition. The City Manager was notified of the damage on April 3, 2023 by Public Works staff and authorized the emergency permanent repair of both sewer segments underneath the Union Pacific Railroad tracks. Engineering and Transportation Department staff developed a phased replacement plan for the two large diameter sanitary sewer lines. Phase 1 of the emergency repairs began on March 26, 2024. It replaced 384 feet of the north and 94 feet of the south sewer main segments between the Union Pacific Railroad tracks and Chestnut Street as shown in Figure 1, below. On October 28, 2024, the City Council accepted Phase 1 of the Emergency Veterans Sanitary Sewer Repairs and Replacement Project. As Phase 1 neared completion, more sinkholes were discovered downstream along the north sanitary sewer main between Chestnut Street and Hansen Way. Because repairs on the north sanitary sewer main were not in the proposed scope of work for Phase 2, Engineering and Transportation Staff requested authority from the City Manager’s Office for additional emergency sewer line repair along the north main. This additional work, titled the supplemental 2024 Emergency Veterans Boulevard Sewer Replacement Project, was added to the proposed scope of work for Phase 2. Phase 2 of the Emergency Veterans Boulevard Sewer Main Repairs and Replacement Project replaced 570 feet of the south sanitary sewer main on Veterans Boulevard from Chestnut Street to the manhole at the intersection of Veterans Boulevard and Hansen Way. The supplemental 2024 Emergency Veterans Boulevard Sewer Replacement Project removed and replaced 315 feet of the existing north sanitary sewer main, slip-lined (a trenchless pipe repair involving inserting a smaller diameter pipe into an existing, damaged pipe) 165 feet of existing sanitary sewer main, and installed 130 feet of a new 36-inch bypass main through Hansen Way connecting the north and south mains. Phase 3 will include the north and south sanitary sewer main segments on Veterans Boulevard between Hansen Way and Walnut Street, given the available budget and clear termination point at the manhole at the intersection of Veterans Boulevard and Hansen Way. The scope of work will involve abandoning the north main from the termination point at Hansen Way to Walnut Street and upsizing the parallel south main. By abandoning the north main, Public Works staff are better able to maintain and operate a single sewer main along Veterans Boulevard. Phase 3 is currently in design and is expected to go out to bid in March 2025. Phase 3 of the Veterans Sanitary Sewer Replacement Project is anticipated to begin construction in early Fall 2025. 6.B. - Page 2 of 5 63