CITY OF SAN MATEO
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CITY OF SAN MATEO
Agenda Report
City Hall
330 W. 20th Avenue
San Mateo CA 94403
www.cityofsanmateo.org
Agenda Number: 14 Section Name: {{section.name}} Account Number: 82-4681 File ID: {{item.tracking_number}} TO: City Council
FROM: Alex Khojikian, City Manager
PREPARED BY: Public Works Department
MEETING DATE: November 20, 2023
SUBJECT:
Central Park Tennis Court Garage Structural Improvements – Contingency Increase RECOMMENDATION:
Approve an increase to the contingency reserve for the construction contract with Angeles Contractor, Inc. for improvements to the Central Park Tennis Court Garage in the amount of $90,000 for a new contingency total amount of $115,000; and authorize the Public Works Director to execute the change orders within the contingency amount.
BACKGROUND:
The Central Park Tennis Court Garage has served the San Mateo downtown community for over sixty years. It is a concrete structure that has 132 underground parking spaces on a single level and six tennis courts on the roof level. In 2020, waterproofing improvements were made to extend the life of the garage until 2030 that requires performing annual assessments to track seasonal movement in the structure. The assessment performed in June 2023 confirmed significant movement and identified damage to specific girder locations, cracking at columns and spalling at perimeter piers. The City engaged ZFA Structural Engineers to produce construction documents to address the damage and on September 18, 2023, City Council awarded a construction contract in the amount of $241,870.66 to Angeles Contractor, Inc. for the repairs. A 10% contingency of $25,000 was established for the project at that time.
Construction began in October 2023 and the following unknown conditions were exposed:
•Additional spalling with exposed rebar was identified at 50% more locations since the assessment in June 2023. •Existing rebar in the repair areas is found to be minimal or non-existent. •Existing concrete at the repair areas have become brittle.
The additional spalling and rebar corrosion is a result of previous damage caused by movement and moisture through the decades. The extent of this damage was not visible during the June 2023 assessment and was revealed during concrete patching and repair. Although the waterproofing project in 2020 prevented additional moisture from recent weather, the structure appears to have been saturated for most of its useful life resulting in the deterioration of the rebar and concrete.
These conditions necessitated additional analysis by the project’s structural engineer who deemed the following additions to the scope of work for the repair would be necessary for continued use of the facility:
•Installation of structural posts have been increased from three (3) to eleven (11), located in areas that require immediate attention.
•Temporary shoring underneath the tennis court surface is required at each post location during installation. •Commissioning of a specialty contractor to provide an x-ray scan of the existing steel reinforcement at the eleven (11) post locations prior to installation is requested by the structural engineer.
Based on the project narrative supplied by the structural engineer, staff recommends increasing the contingency in an amount of $90,000 to cover the costs for the work in addition to the original scope that has been identified and for any
CITY OF SAN MATEO
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other additional work that may be discovered through the construction period such as:
•Additional repairs to concrete areas that have shifted during construction. •Additional posts, beams, and shoring as required by the structural engineer due to movement during construction. •Removal or alteration of existing live and dead loads at the tennis court level.
The scope of repairs will be limited and based on maintaining the integrity and increasing the use life of the structure for seven (7) years. The garage structure is scheduled to be removed and the tennis courts relocated in 2030 as part of the Central Park Master Plan. Work is projected to be completed at the end of November and the garage re-opened for parking in December 2023.
BUDGET IMPACT:
There is sufficient funding available in the Downtown Parking Improvements (461001) project for the recommended contingency increase.
ENVIRONMENTAL DETERMINATION:
This project is categorically exempt from CEQA as an “existing facility,” because it consists of the operation, repair, maintenance, permitting, leasing, licensing, or minor alteration of existing public or private structures, facilities, mechanical equipment, or topographical features, involving negligible or no expansion of existing or former use. (CEQA Guidelines Section 15301.)
NOTICE PROVIDED
All meeting noticing requirements were met.
ATTACHMENTS
Att1 – Project Narrative
STAFF CONTACT
Steve Wu, Project Manager II
[email protected]
(650) 522-7345