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�. - % %% Sinkhole , Geotech, Inc. � Geotechnical &Structural Consulting 21859 State Road 54, Lutz, Florida 33549 ' foundation needs to meet a more satisfactory level, also providing a future support as a ' preventative from settling of the underpinned area. ' WHEN SHOULD UNDERPINNING BE USED? ! There is a variety of reasons when underpinning should be used. When buildings are on unpredictable land, there is often a possibility�the foundation will become unstable. In this ' situation, underpinning may be necessary. Here are a few examples of situations that would require underpinning: • Structure is not even: re-leveling the structure ' ' � Cosmetic/structural cracks: closing of wide cracks caused by excessive settlement i • Soils have changed or cavities were created: bypass weak soil layers • Soils have not been completely idi ntified before construction began: pre- ' construction underpinning , • The foundation may no longer be sti ong or stable enough for support of the ' structure: foundation augmentation • The structure's purpose may have changed: meeting the weight increase on the foundation ' • Structure needs additional foundation capacity to footings or mats with too little bearing capacity (building movement or ground consolidation is excessive) • Distressed or undermined Structure needs support: a catastrophic event (e.g. I ' erosion,landslides,burst pipes, mine subsidence, etc.) • Adding load capacity to an existing foundation system to accommodate a seismic retrofit or addition of new structure,building stories, etc. ' • Cost considerations: homeowner prefer�ence to secure the foundation . . ' The plan for the Southeast Property Acquisitions LLC Properry utilized 27 underpinning points. The underpin piers were hydraulically driven down into the underlying soils to ' refusal or a pressure that was appropriate to avoid damaging the structure based the condition of the foundation at each location. The pier depth ranged from 7 (piers no. 11, 15, 16, & 19) feet to 28 feet (piers no. 20 &22). ' ' The jacking of each pier was monitored and terminated at a pressure that was appropriate to avoid damaging the structure based the condition of the foundation at each location. All , piers were jacked to a pressure of up to 2,000 to 3,000 psi, which provides more than 24,000 pounds of foundation support per pier. When the piers reached the ultimate support depth, each underpin bracket was secured to the pressure pier with a 5/8' pin. The ' jacking depth and pressures of each individual pier are presented in tabular form in the appendix of this report. � i ' I j Southeast Property Acquisitions LLC Property ' ' Pro'ect No.:SGT-P1507-9167 J iPage 2 of 3 'I ' i