The foundation micropiles are now complete and the next phase of work to stabilize the building foundation has started. Wysong Construction is installing a shoring system in the basement using heavy wood timbers to temporarily support the building while they install new concrete pile caps under the existing building footings. Once the shoring is installed, Wysong will carefully excavate under the existing footings, install reinforcing steel(rebar), and place new the concrete pile caps. The new pile caps will also be connected to the micropiles by encasing them in the concrete cap. When completed, the entire building weight will be transferred to the new pile caps and micropiles that are embedded in the bedrock 60 feet below the surface. The top of the building is now covered in a heavy plastic sheeting referred to as shrink wrap because as it was installed, it was heated to make it taut. This cover will provide weather protection for the structural reinforcement work that is underway at the top of the building. The multi-phase reinforcement includes brick removal, a new concrete beam that will tie the perimeter of the roof dome together and new structural steel members to strengthen the upper portions of the structure. Inside the building, the abatement work is complete up to the 2nd floor. Shotcrete, a system of applying concrete through a hose at high velocity, will be used to strengthen the interior perimeter of the building. The existing wood framed walls and ceilings have been removed already on the 1st and 2nd floors to expose the interior brick surfaces. Rebar is being installed next to the brick and attached at regular intervals with high strength epoxy. A minimum of 8" thick shotcrete will be applied to interior walls from the basement to the top of the 3rd floor. All work is progressing on schedule.
Hayward Baker and Wysong Construction continue to install piles around the exterior building perimeter and in the basement area. Over 120 of the total 248 piles have been installed so far. Historic materials have been removed on the first and second floor. Diani Building Corp. will move up to the 3rd floor next week and start removals on the upper floors of the building. Channel Coast Construction has sealed off the 1st floor to remove all lead-based and asbestos containing materials as they demolish interior walls, ceilings and flooring. The hazardous materials abatement will be done throughout the building during the next two months. The second tier of scaffold will be erected around the upper dome next week followed by the clay tile roof removal. All of this removal work at the upper dome area is required for the major structural upgrades that must be done at the top of the building which will include a new concrete perimeter beam and structural steel reinforcement. Similarly, the interior wall demolition will allow access to the original building walls that must be reinforced to resist seismic forces. Starting from the foundation piles, the process of stabilizing the building from the ground up is underway.
Diani Building Corp. started historic material removals this week inside the building and at the 4th floor roof area. Every door, door trim, window trim, and baseboard is assigned an IIN (item identification number), which is used to track the piece from removal to reinstallation. In addition to the IIN, all historic material is photographed before removal to document its condition. The removal process requires extreme care and handling of these materials that are almost 100 years old. All of the materials are being stored off-site in secured locations. The original wood doors will be restored and re-fitted for new hardware before they are returned to project next year. The terra cotta caps have been removed around the perimeter of the roof. They are also treated has historic material and they will be re-installed later in the project. The first scaffolding on the project is now in place around the exterior of the upper dome area. The clay tile roof will be removed starting next week as the first step in dismantling the entire roof dome which will allow the seismic repair and upgrade work to begin. The original clay roof tiles will be blended with new replacement tiles to restore the roof to its original condition when all of the repairs and upgrades are complete. Micro pile installation will start around the exterior of the building next week. 64 micro piles have been installed so far in the basement.
40 micro piles have been installed so far under the building foundations. We are averaging 4 to 5 piles per day. The drilling conditions have been fairly consistent with the bedrock at 40 to 50 feet below the building. The challenge has been to clean up the large quantity of muddy water from the drilling operation that accumulates quickly in the basement area. Wysong Construction is pumping the muddy water into holding bins and using small Bobcat excavators to haul the mud out of the basement. The micro pile installation is expected to be complete by mid-October.
The two remaining trees closest to Palma Ave. are being cut down. Jim Wilkins, president of the Atascadero Historical Society has big plans for the larger trunk wood. He plans to have the wood milled into various pieces of usable lumber to be used on projects that will enhance the Historical Society grounds and the City Hall Project. Some of the wood is to be made into collectible souvenirs which will be sold to offset the expenses incurred to move and mill the wood. The Atascadero Historical Society's proceeds from the August 9, 2011 Tuesday in the Park BBQ will be utilized to begin the milling process so please join them by purchasing dinner tickets.
Diani Building Corp. has completed the historic building component marking. They will start to remove these items next week and prepare the building interior for abatement work, which is the next phase before actual interior demolition begins. Alpha Fire Protection completed the dry stand pipe repair and the Atascadero Fire Department approved the installation. The fire sprinkler system has been shut down and it will be removed as part of the interior demolition work. Alpha will install a new fire sprinkler system that provides complete coverage of all building areas in the new construction phase.
Micro pile installation started in the basement area on July 13th. Hayward Baker and Wysong Construction are focused on installing the new piles under the existing foundations that support the center or rotunda area of the building. Some of the greatest building loads are concentrated in this area because the highest part of the building sits on these foundations which includes the grand dome roof. The sequence of micro pile installation is based on carefully re-supporting the building foundations without risking any building movement during the foundation phase.
Diani Building Corp. is now inside the building marking all historic building components that will need to be removed and saved. Some of these components include the original wood base, wood doors, and wood widow trims. All of these items will be carefully cataloged, removed, stored, and re-installed in the new construction phase. Alpha Fire Protection has started to repair the dry standpipe system to insure there is proper fire protection during construction. Alpha, Scott Murray Plumbing ,Taft Electric and Santa Margarita Construction will remove piping, mechanical and electrical systems through out the building and basement once demolition gets underway in August.
Click here for Micropiles Technical Summary
The test pile installation was completed this week and load tests started. The purpose of this testing is to insure the micro piles will support the weight of the building, which is their primary function in the Historic City Hall Restoration Project. The new piles are taking the downward force of the building which is compressing or pushing down on them. The load tests this week are simulating this downward force using an hydraulic ram that can create the weights that the building piles will be put under. In fact this ram put more than twice as much force on the piles and this is part of the testing requirement. The highest compression force used this week was 392,000 pounds which was put on the pile with 16 feet embedment into the bedrock. This means the test pile supported over 200% of its’ design capacity and more than exceeded Hayward Baker’s expectations . The testing will be complete by July 15th. Hayward Baker and Wysong also mobilized in the basement area this week to prepare for the start of the pile installation under the main building foundations. We completed pre-construction meetings with Scott Murray Plumbing from Salinas and Republic Elevator from Goleta as we prepare to mobilize more contractors on the project.
Hayward Baker completed the micro piles for testing in the northwest corner of the project site this week. They continue to install the test piles in the southeast corner. The deepest pile drilled so far has gone down 95 feet with 39 feet going into solid bedrock. Soil and bedrock conditions have been consistent with the exploratory borings done by Earth Systems Pacific as part of the soils report they completed in 2004. The drilling effort has been difficult at times because the bedrock is dense and this is ultimately positive for the project. It means the micro piles will be securely anchored into the bedrock below. There have been more deliveries of material and equipment to support the micro pile installation, which is a preview of the months ahead as more contractors mobilize on the project. Diani Building Corp. from Santa Maria and Taft Electric from Solvang are moving into their field offices which are located in the same building as Bernards Construction Management.
Hayward Baker Geotechnical Construction mobilized on the project this week. They are a subcontractor to Wysong Construction who is doing all of the foundation work. Hayward Baker will be drilling and installing over 250 micro piles under the existing building foundations. This is the first step in stabilizing and reinforcing the existing foundations. Several pieces of equipment have been set up around the site including the yellow cement tank you can see from the Palma Ave. side of the project. Hayward Baker will use a small, compact drilling rig that can fit in the basement to bore 8” diameter holes into the bedrock below with some holes as deep as 85 feet down. As the holes are completed, cement grout is pumped down the 7” steel pipe that is in the center on the bore hole, which fills the pipe and the hole. The first phase of work will be drilling and installing test micro piles in two exterior locations on the site, one in the northwest corner and one in the southeast corner.
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