3900 S Bristol St - Soils Report

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J. C. Penney Company, Inc. Page 3 November 22, 1971 (Our Job No. A-71009) at footing level. . If the soils are excessively soft, it may be necessary to deepen the footing excavations and place a layer of compacted gravel for foundation support. The maximum settlement of the proposed basement will be on the order of one-half inch. Excavation of the Basement Walls If the site is properly dewatered, and the necessary space is avail- able, temporary unsurcharged embankments may be sloped back at 3/4:1 (hori- zontal to vertical) in lieu of shoring. For design of basement walls it may be assumed that properly drained backfill will impose a lateral pressure equal to that developed by a fluid with a density of 30 pounds per. cubic foot. All required backfill should be properly compacted to at least 90% of the maximum density obtainable by the ASTM Designation D 1557-70 method of compaction modified to use three layers instead of five. The required backfill should be mechanically compacted in layers and not flooded. The on-site soils consist of expansive clay materials and are not recommended for use as backfill. Preferably, backfill should con- sist of imported relatively non-expansive soils. The backfill, however,.should contain sufficient fines so as to be relatively impermeable and minimize the infiltration of surface water into the backfill. Walls below grade and the basement floor should be waterproofed. Subdrain To prevent the development of hydrostatic pressures on the basement walls and floor, we recommend that a subdrain be installed beneath the floor and behind the basement walls. The requiÂ·red subdrain could consist of a layer of filter gravel* approximately one foot in thickness beneath the floor slab. The gravel layer should be drained by subdrain pipes leading to sumpareas equiped with automatic pumping units. The drain lines should consistof perforated pipes, placed with the perforations down, in trenches extend-ing at least one foot below the filter material. The trenches should bebackfilled with filter gravel material. The drain lines should be spacedapproximately 30 feet apart within the interior of the structure. In addition, a perimeter drain should be installed around the outsideof the basement wall. The perimeter drain should be surrounded by filter material, and the filter.material should extend at least five feet above thebasement floor. However, the filter material should not extend closer than RECEIVED DEC 1 1971 City of Santo Artu Dept. Bldg. Slly. & Hou,Ing