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11 also was locally observed to be mixed with glass. At the explored locations, glass was encountered to a maximum depth of 16 ft. Where soil predominates, the surface fill materials are judged to be medium dense with localized loose and dense zones. Even where glass was not observed to be present, the sands are likely to be uncontrolled fill. Beneath the depth of alteration, the soils consist principally of alternat- ing deposits of clay and sand. A stratigraphic sequence composed primarily of lean clay was encountered at about 14- to 16-ft depth. At the six boring loca- tions within the plant area, the lean clay extends down to depths ranging from 30 to 39 ft. The clay is commonly sandy in texture and is interbedded with sand seams, layers, and lenses. The percentage of sand inclusions appears to be higher in the lower one-third of the stratum. In two of the borings (B-1 and B-5) , a 2- to 4-ft-thick sand layer was encountered near the base of the clay. The lean clay typically is stiff in consistency. Dense to very dense, silty fine to medium sand was encountered below the lean clay in all six borings. Borings 1, 4, 5, and 6, were terminated in this stratum. The surface of the silty sand was encountered at about E1 -20 ft to El -25 ft. In borings 2 and 3, the silty sand graded to a fine to coarse sand. The total thickness of sands was 11 ft in both borings. Very stiff, lean clay was encountered below the sand in borings 2 and 3. In boring 3, the lean clay extended down below 62-ft depth, the maximum depth explored. General subsurface profiles are presented on Plates 34 and 35. Glass and Glass By-Products Our observations in the five trenches that were excavated in March 1988, are shown on Plate 12. The approximate locations of these trenches also are shown on Plate 12. In the trenches, we observed extensive deposits of broken glass. The glass fragments are flat, angular pieces of glass that are typically on the order of 1/4-inch thick. Individual pieces range from fractions of an inch to 12 inches in size. In some trenches, the layers and lenses of plate glass are more than 2 ft thick. Where soil is intermixed with the glass, the soil consists primarily of sand and silt. The soil exposed in the trenches and encountered in our borings below or above the glass layers also consists primarily of fine sands and silts. 1144A/CC-11 C:'McClelland