616 PECKS DR 2018-01-01 MF Import

� ' � M Everett School District W-6884 � � = 15 June 1990 Page 7 � H �u � N "O y N �1 C Z � � A second design option would be available if the owner could accept some risk of N � � settlement, and if relatively Iight building loads are expected for the proposed building � y addition in the courtyard. The upper, loose to dense, sands (uncontrolled fill) at this y N / �py location could then be partially removed and replacetl with structural fill. With this Q O N � � r approach, it is not possible to accurately estima�e�tfie settlement which may occur. As � � an increasing portion of�e�Cisting fill soils are e�rioved, the anticipated settlements would be reduced. As a minimum�we consi�d r it appropriate at this location to remove 2 feet of er.isting fill soils from beneath tF�e�ase of the proposed light footing subgrade levei. The compact the resultirn sub��e s1'i�u�be compacted to 90 percent relative density using ASTM:D 1557 as the ,�� + �.:rr� snd an�excessively soft or yielding areas at this elevation, or any zone�s hic,:; �an�7�t be compacted ta his minimum density should be overdecorate to n fnore than 4 feet below the proposed,footing subgrade elevation, ard subsequ��ackfilled to subgrade eievation with structural fill. If the base of the resulting ov -excavation is not suitable at that levet for placement�o( structural fill, quarry ��;^ spalls ould be placed to stabilize the bottom and prevent pumping� the subgrade � a d contamination of the structural fili. We wo�id recommend using�a�allowable 1 '�� ��aring pressure of 1500 psf with this o�ti_on• 1 E;:terior footings should penetrate at least 18 inches below lowest adjacent grade for �� frost protection. Interior footings neea only penetrate 12 inches below adjacent grade. I �� Footing� should have a minimum width of 18 inches. If loose or soft materials are left within the foundation area prior to concrete placement, settlements rnay significantly �-t�) increase. Therefore, it would be appropriate to have all footings inspected by the geotechnical engineer or his representative immediately prior to concrete placement. a 1�� . All footings must be founded on the prescribed bearing stratum and should not be set � � on or above soft, loose or disturbed native soils or uncontrolled fiii. Because the site soils exhibit a high silt content, site work in the presence of water or during wet weather �a�� would disturb the bearing stratum. Consequently, the contractor should avoid disturbance of those bearing soiis and limit traffic across the building pad or foundation areas during wet weather. To minimize disturbance associated with foundation or form work and reinforcement bar placement, the use of a lean concrete "mud maY' or a quarry spall or gravel working surface may be warranted. We recommend that the condition of