1817.3.1 Assessment of the building and the subsurface conditions.
BC § 1817.3.1
The engineer shall assess the condition of the existing building, and the subsurface conditions of the construction site and adjacent property, to an extent sufficient for determining acceptable method(s) of support, including underpinning or alternate methods of support. As necessary, the assessment shall be based on visual observations, calculations, review of the geotechnical report prepared for the project in accordance with Section 1803.6 and review of other available documentation. The investigation shall include, as necessary, but need not be limited to, the following items: 1. An evaluation of the vertical load path of the building as it relates to the location of the proposed underpinning or alternate method of support.
2.An evaluation of the lateral load path of the building as it relates to the location of the proposed underpinning or alternate method of support.
3.Calculations of the vertical and lateral loads at the foundations to be underpinned or supported by an alternate method of support.
4.A determination of the type and condition of the above grade elements to be supported or potentially affected by the work.
5.A survey of deviations from plumb or horizontal position of the building.
6.Identification of conspicuous structural defects, including but not limited to: bowing, significant cracking, structural degradation or unusual slenderness. A detailed description of such items shall be provided, with photographs and mapping if possible.
7.A determination of acceptable thresholds for maximum vertical and lateral movement, maximum permissible vibrations, the required monitoring and the protocols for exceedances.
8.A determination of the type and condition of the foundation elements to be supported or potentially affected by the work.
9.A test pit at each substantial change in foundation type or building geometry. Records of the test pits shall include the following: a. A description of the construction materials and condition of the footing, foundation wall and/or foundation system. b. The bottom elevation of the wall(s) and/or footing(s). c. The classification of the soil or rock the foundation bears upon. d. Photographs and sketches of the test pit.
10.An assessment of the allowable bearing pressure of the soils supporting the existing foundation(s) per Section 1806.
11.An assessment of potential reductions to the allowable bearing pressure due to the proposed excavation.
12.The lateral earth, surcharge, and water pressures that will be present on the elements of the proposed underpinning or alternate method of support.
13.An analysis of the subsurface conditions and their potential impacts on the underpinning or alternate method of support work such as, but not limited to: high water table and need for dewatering, loose soils, potentially running soils, presence of boulders, or other factors that could impact the design or construction of the underpinning or alternate method of support.
14.An assessment of the allowable bearing pressure of the soils supporting the underpinning or alternate method of support during the installation sequence and in the permanent condition.
15.An assessment of the anticipated settlement during the underpinning or alternate method of support, and soil and foundation work.
16.Any additional information requested by the commissioner. (Am. L.L. 2023/077, 6/11/2023, eff. 6/11/2023) Editor's note: For related unconsolidated provisions, see Appendix A at L.L. 2023/077.
