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TECHNICAL MEMORANDUM <br />Page 4 <br />June 3, 1992 <br />SAC31583.AC.ZZ <br />made. The conclusions and recommendations contained in this technical memorandum were <br />based on the applicable standards of the consulting profession at the time this memorandum <br />was prepared. <br />CH2M HILL is responsible for the conclusions, opinions, and results of. engineering analyses <br />contained in this report as they pertain to the specific project and locations discussed herein. <br />If conclusions or recommendations based on these data are made by others, such conclusions <br />or recommendations are not the responsibility of CH2M HILL. <br />Field Exploration <br />The field exploration consisted of four soil borings drilled between April 29, 1992, and May <br />1, 1992. Figure 1 shows the approximate location of these four borings, designated as BH -1 <br />through BH -4. Pitcher Drilling Company of Palo Alto, California, was subcontracted to drill <br />the soil borings. CH2M HILL personnel specified the locations, depths of borings, and <br />sampling intervals, and observed the drilling and sampling operations. <br />The borings were 4 -7/8 -inch diameter and extended to depths ranging from 42.5 to 101.5 <br />feet. The borings were advanced using mud rotary drilling methods with a truck -mounted <br />Failing 750 drill rig. As each boring was completed, the hole was grouted to the surface <br />using a neat cement grout. The borings were grouted from the bottom upward using a 2 - <br />inch drill pipe as a tremie. <br />Relatively undisturbed samples were obtained using a 3 -inch outside diameter Shelby tube <br />sampler (ST samples) or Pitcher Barrel sampler (PB samples). The Pitcher Barrel sampler <br />was used to obtain samples of very stiff clay where the Shelby tubes could not be pushed. <br />This sampling was performed in general accordance with procedures for Thin -Walled Tube <br />Sampling of Soils as described by the American Society of Testing and Materials (ASTM), <br />Standard D1587. Disturbed soil samples were obtained from the borings using a 2 -inch <br />outside diameter split -spoon sampler, driven as described for the Standard Penetration Test <br />(SPT), ASTM Standard D1586. <br />Soil recovered during the drilling program were visually classified by a CH2M HILL <br />engineer in general accordance with ASTM D2487 and D2488. The soil names on the <br />E <br />