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' Aucuct 28, 1991 BAI_RI Q CHANG ASSOCIATES File No. 1525-69 The optimum moisture content for near surface site soils is 16.5% based on the moisture to dry density relationship curve developed in the laboratory. The in-situ moisture for the upper .P-/ 5 feet of on-site soil is about 4% to 8% over the optimum. Generally, it is necessary t reduce the soil moisture in order to achieve proper compaction. However, it may not a problem if the on-site soil is improved by lime treatment. The moisture to dry density relationship curve for the lime treated soil should be performed prior to site preparation. Presented below are general recommendations for site preparation and grading in normal weather condition. Special recommendations for site grading in wet weather condition are presented in the next section of this report. a. Abandoned underground obstructions, if any, should be excavated and removed. The voids created by these excavation and removal should be backfilled in accordance with the following recommendations for structural fill. b. All areas to be graded should be cleared of debris and stripped of vegetation and organic material. We estimate this will require the removal of 2 to 5 inches of near surface material. The material generated from site stripping may be placed in landscaping areas, however, they should not be incorporated into structural fill. C. There are trees on the site which may require removal. The root system of these tree stumps should be thoroughly grubbed and the cavity-created by the removal should be cleared of all loose material and dished to provide access for compaction equipment. d. The top 2 feet of the near surface material underneath the proposed Mini Market building should be overexcavated and thoroughly mixed with sufficient quantity of lime. The limits of lime treatment area should extend a minimum of 5 feet beyond the building footprint. If lime treating the pavement subgrade area is selected, the treatment area should extend to the entire site, and the treatment thickness should be at least 12 inch below the finished subgrade soil. e. The optimum amount of lime required for effective swell reduction is determined by laboratory test. Thorough processing the soil is essential to achieve uniform mixing of the additives. Also, adequate number of field testing should be performed to verify the end result. f. The subgrade of all dished areas, areas to be overexcavated, areas to receive fill, and building pads at grade should then be scarified to a minimum depth of 12 inches and Pate 6 of 17