3105 PINE ST 2018-01-01 MF Import

Voth Brothers Construction, Inc. E-1201-1 , _ October 20, 1980 Page 4 Subsurface !» Ouc test borings indicate the site is immediately underlain by a surficial layer of loose to medium dense silty sand and ,� sandy silt with some gravel and organics. This surficial layer is about 2.5 to 4 feet thick. Beneath this surficial soil layer the borings encountered a very dense gray glacial till to the full depth of our exploration. Glacial till is a heterogeneous mixture of gravel, sand, silt and some clay, deposited 12,000 to 14,000 years ago during � the advance of the Vashon Glacier over the Puget Sound Basin. The ice was a lobe of a larger continental ice sheet which cov- ered the majority of Western Canada. During the greatest �axtent „ of the Vashon Stade, a glacier covered most of the Strait of Juan de Fuca and the entire Puget lowland. The maximum ice � � thickness has been estimated at 3,000 to 4,000 feet. This con- siderable weight of the ice consolidated all the underlying sedi- " ments. � . Near surface groundwater was encountered as perched water , above the impervious glacial till in the test pits from our pre- � , vious study. During drilling of the borings for this study, water was encountered at a depth of about 17 to 18 feet. On Sep- tember 21� 2980 groundwater was measured at a depth of about � 17.5 feet and 15.4 feet in Borings B-2 and B-4, respectively. , DISCUSSION AND RECOMMENDATIONS I • ,., General � . As described earlier in th� previous section, the site is basically underlain by glacial till at relatively shallow " depths. These dense overconsolidated stratam should provide ade- quate bearing for the proposed structures supported on conven- tional footings bearing on undisturbed dense glacial till at the •- basement level. The single-story section of the proposed facil- ity may be supported on the undisturbed medium dense silty sand to sandy silt below the topsoil layer. The surficial loose _ soils are not suitable for support of building loads. Building loads must, therefore, be extended beneath these materials. The following sections of this report present more detailed - recommendations for various geotechnical engineering aspects of the project which should be incorporated into the project design and construction. This report has been prepared for specific - application to this project in accordance with generally accept- ed geotechnical engineering practices for the exclusive use of Voth 8rothers Construction, Inc. and their representatives. No _ other warranty, expressed or implied, is made. Earth Consultants, Inc � _.