soil observation/testing-1991 - Laserfiche WebLink

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1 .. . ' � �. � I��I`� . ... . � �,.�:�,�': . . PREREQUISITES FOR SOUN� ENGINEERING PRACTICE � In order to properly evaluate the foundation soiis at a building site, it is imperative fot our fi�m to know exactly where the building will be placed, its size, and the elevation of the foUndation elements. Without this information, a judgement regarding the adequacy of the preparatory' foundation earthyvork is not possible. This project data is especially critical in situations when the excavation exte�ds below Lhe foo'ting � grade and compacted fll will be required to attain building elevations. In these sitU�Eioris, the excavation would require lateral oversizing to provide suitabfe lateral distribUtion of tNe footing loads. � Offset batter boards or the building lines stakes provide the best on-site verification of the build- ing location and size. It must be recognized that Twin City Testing and Enginceri�g Laborato�y, Inc. does not practice in the field of surveying. We, the�efore, must �ely on staking by otl�ers. If Twin City Testing is required to perform the survey, we will retain a licensed surveyor and in- voice our client for the amount per our cu��eni fee schedule. Provision of the building foundation . plans is also important so that we may properly perform our engineering judgements. If the construction is redesigned or otherwise moved subsequent to ou� work, we should be i�formed so our firm can assess if additional engineering observation is required or suggest souhd engineering alternatives. We cannot be responsible for any soil found�tion system if the structure has been relocated with �espect to the excavation subsequent to our observations. GENERA� OVERSIZE REQUIREMENTS Because of the lateral distribution of foundation pressures with depth, lateral oversizing is re- qui�ed in an excavation where unsuitable soils extend below plan footing grade. tlie lateral oversize scheme p�ovides compacted fill material beyond the exterior footing limit3 where fil) is required below footing elevation. The degree of lateral oversizing is depende�t upot� the sur- rounding soil's ability to resist lateral movement. Although we generally �ecommend the lateral � ovenize be at least 2' plus the depth of fill below bottom of footing elevation, each project must be evaluated separately. For example, in extremely compressible swamp or organic soifS,th�over- size should be increased to 5' plus twice the depth of excavation below footing grade. due to the variations in the required oversize, an engineering judgemertt must be made to establish the neces- . . sary extent of the oversizing. Diagrams illustrating typical oversiiing dimensions �� included � below. SG- 118(5-II2 ) � � tuuin c�tY testinq �.�«�«,