500 LAUREL DR 2016-01-01 MF Import

Geotechnical Engineering Study Page 19 00-2267 Three Story Addition - 500 Laurel Street, Everett January 31, 2001 should be sloped back at a gradient of 1H:1V, or flatter. Modification of these excavation slope gradients may be possible, but will be dependant on the nature and condition of the materials exposed in the basement excavation at the time of construction. If a utility trench excavation is to extend to a greater depth than four feet, the utility contractor MUST �mploy a steel trench box while installing utility pipes. This will help preserve the inte;;rity of the excavation and provide a relatively safe working environment for his workmen. Failure to use a trench box cou!d result in trench sloughing or collapse and development of a significant threat to his workers health and safety. The earthwork contractor should request that all excavations be observed by our representative to verify that conditions are as anticipated. If warranted, supplementary recommendations can then be developed to enhance stability. Such recommendations should include, but not necessarily be limited to, flattening of slopes or installation of surface or subsurface drains. It is also critical that all exposed cut, fill or trench slope faces be protected against erosion. This can typically be managed by covering the exposed face with a sandbagged or pegged-in-place impermeable plastic sheeting. In addition, we recommend that a shallow swale or ditch be dug along the toe of any excavated slope to collect the surFace water runoff. The collected water should be directed to a positive and permanent discharge, such as a nearby storm drain. Conventional Spread Footing Foundations General: As indicated earlier, it is our professional opiniun that the proposed addition can be supported on conventional spread footings bearing in the firm and competent undisturbed or redensified shallow silty sand or sandy silt soil. Altematively, if preferred, the footings may bear on at least two feet of compacted structural fill placed over properly redensified in-place silty sand or sandy silt soil. Where compacted structural fill soil is used it should extsnd for a similar horizontal distance beyond the foundation perimeters equal to, or greater than, the thickness beneath the footing. This helps to avoid the risk of a lateral shear failure occurcing beneath the footings. � I �