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BACKGROUND The fire training tower, located at the Operations Services Center, was designed in 1987 by architect Jack Bras of Pleasanton and structural engineer Oliver Baer of Hayward, and was constructed in 1987-1988. The structure is seven stories tall, including a partially sunken basement, and is irregularly shaped with overall dimensions of 53 feet by 56 feet by 70 feet from the basement floor to the top of the structure, and consists primarily of reinforced concrete. The structure is unoccupied and is used exclusively for training purposes. One of the primary purposes of the structure is to train personnel during live fire exercises. These exercises involve burning bins of hay inside one of two "burn rooms" within the structure (one room in the basement and the other on the second floor), creating a very hot and smoky environment. The temperature within the room is allowed to reach up to 800°F before the fire is extinguished. While there are insulating panels installed on the walls and ceiling of the burn rooms intended to help protect the concrete, the concrete still gets very hot. These temperatures do not last long, but the fires are repeated several times during an exercise. Up until 2017, exercises were held an average of six times per year. In 2017, the live fire exercises were placed on hold as damage was observed at various locations within the structure and a structural assessment was needed. The observed condition in the basement and lower burn room is exhibited in Attachment 2. In August 2018, Finn Design Group, Inc. (Finn) conducted a visual observation of the fire training tower. This was the first structural assessment performed since the original construction of the tower. The inspection identified that damage occurred to the structure both as a result of its use as a fire training center (high temperature subjection) and as a result of general exposure to the elements. The assessment found damage to the concrete in and around the burn rooms that resulted from the high temperature associated with fires, and damage to the exterior as a result of, or exacerbated by water intrusion. In addition, the structural engineer recommended testing of the existing concrete strength due to a concern that the concrete could have suffered permanent loss of strength from potential exposure to high temperatures. In February 2019, BSK and Associates (BSK) and Finn performed coring and material testing of the existing concrete and determined that no loss of strength of the concrete had occurred and that all tested locations (except one) were above the 2,500 psi design strength. On the third-floor exterior slab, one set of samples was below the design strength. The set was reviewed and deemed still structurally sufficient for the original design of the building. It is believed that the low strength was potentially due to the original construction and not associated with the live fire activities performed in the building. The 2019 report recommended the following repairs be completed to resume the full use of the building and extend its useful life: • Existing spalls (floors, ceilings, and walls) should be repaired with a specialty applied mortar topping and significant cracks in the concrete should be epoxy Page 2 of 5