11830 19TH AVE SE 2016-01-01 MF Import

� Seahorse hestaurant 18 March 1988 W-5583 Page 6 the ASTM:D 1551). Due to the silty nature of the site soils, prerolling and ' compaction can only be done when the soils are at or very near optimum moisture. The optimum moisture is that which allows the greatest soil density under a given compactive effort. Prerolling and cornpaction of wet soils may reduce them to a mud and require extensive removal of the disturbed soils with increased cost. The � need for and advisability of prerolling may need to be assessed in the field should construction proceed in wet weather. Due to the presence of "perched" ground water and the proximity of the lake which is a source of ground water recharge, equipment movement during clearing may turn the upper site soils into mud. Care should be exercised to minimize disturbance which would result in difficult site conditions during grading and construction. Any soft, wet or significantly organic areas disclosed by prerolling should be excavated as necessary to reveal, firm, non- organic soils and backfilled with structural fill as described subsequently. The bulk of the near-surface site soils are silty an,! consequently highly moisture- sensitive. These silty soils are highly prone to disturbance when in wet site conditions. To reduce site disturbance, the contractor should minimize traffic above prepared subgrade areas, and direct surface and ground water away from the work areas. In very wet conditions, the use cf a working surface of quarry spalls or sand and gravel may be required to protect the subgrade, especial ly from vehicular traffic. Structural Fill All fi11 p7aced in the building areas as well as under parking lots and sidewalks and for the backfill of utility trenches should be placed in accordance with the reconenendations herein for "structural fill". Prior to the placement of str•uctural fill, all surfaces to receive fill should be prepared as previously recommended. Structural fi11 should then be placed in loose lifts not exceeding 8 inches in thickness. Individual lifts should be compacted to a uniform density of at least 90 percent of the modified Proctor maximum density (ASTM:D 1557). We recommend that a representative from aur firm be present during the placement of structural fill to observe the work and perform a representative number of in-place density