2016-00571 - addition / remodel - Laserfiche WebLink

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i � Project Number: 016-0019-5391 Page 2 Water level measurements were made in the boreholes during and at the completion of the borings. Based on this data, water was noticed at boring B-1 at the time of our field work. Water level was about 12 feet below the present grade at boring B-1. No water was noticed at boring B-2. Water level measurements in clayey soils may not accurate as it takes longer time to stabitize. In general,water may fluctuate throughout the year depending on several factors. We understand the new addition will be a one-story with walk-out basement. The maximum plan dimensions of the addition will be 29 feet by 34 feet. The structure will be of wood frame construction supported on load bearing walls and possible interior columns. Currently, we have no information on actual foundation loadings. However, we anticipate the maximum column loads may be on the order of 50 kips and perimeter wall load will not exceed 2 kips per lineal foot. We also understand the new addition will match the existing structure. The excavations for the basement floor, south and west frost footing trenches were completed before our field work. The north and east footing lines were also excavated to about the bottom of basement floor elevation. The existing fill, and very soft peat noticed at boring B-1 should not be relied upon for new foundation support because of limited strength and compressibility potential. To remove and replace these soils will require up to 15 feet of excavation at boring B-1. Conventional excavation and refill procedure may not be desirable due to depth of excavation and wet condition. In our opinion, a deep foundation system may be suitable for supporting the proposed addition. A deep foundation system of helical compression anchors may be considered. Other deep foundations may be used, such as driven piles. However, because of relatively smaller size project, near an existing house and potential vibrations from driven pile installation, in our opinion, a deep foundation system of helical compression anchors may be more applicable at this site. Helical compression anchors have the advantage of minimal site surface disturbance. In addition,there is little or no potential negative (downdrag) load on the anchors from the compressible soils. We recommend the foundation system consist of helical compression anchors. A helical configuration consisting of three helixes of 10, 12 and 14 inches in diameter may be used. The capacity for this anchor configuration should be 15 kips per anchor. Other configurations will yield different capacity. The capacity includes a safety factor of 2.0 against soil bearing failure. The maximum final torque of each anchor should be documented to verify the capacity. fn addition, a quick load test may be performed on one or more anchors to determine the actuaf anchor capacity attained. .�s@O Engineering Consultants Inc