406 SE EVERETT MALL WAY BASE FILE 2018-01-02 MF Import

Auto Mall Associates flay 16, 1986 E-2976 Page 7 with cement treatment or reinforcement such as geotextile or Tensar grids. We will be glad to provide the design for these conditions. The rock should be hard, sound, durable, free of seams and cracks, and broken in cubical ;hapes. The rock density should be at least one hundred sixty-five (165) pcf. Six -man rock should weigh at least four thousand (4000) pounds. Four -man rock should weigh at least twenty five hundred (2500) pounds. The face of the rockery wall should be sloped no steeper than approximately 1:5 (H:V). Each row of rock should be well seated and thoroughly tamped and driven into place having as few voids as possible. Tlie rockery derives its support partially from friction between individual rocks, therefore, point contact of rocks should be avoided wherever possible. Succeeding layers of rock should be placed so that rocks overlap each other. The filter rock behind the wall should consist of crushed angular rock with a three inch maximum size. The filter layer should not be less than twelve (12) inches in thickness. To reduce transportation of fines through the filter layer, a filter cloth should be placed between the excavated surface and the filter rock material. A perforated drain should be placed at least six inches below the bottom course of rocks. We recommend that the placement of all rockeries be performed under the observation of a representative of Earth Consultants, inc. We will be available to meet with you and your rockery contractor to discuss these matters in more detail. Please note that a rockery is not intended to function as an engineered structure to resist lateral earth pressures, as a retaining wall would be. The primary function of a rockery is to cover the exposed excavated surface and thereby retard the erosion process. In addition, some lateral support is provided by virtue of the weight of the rock. However, since this support depends on the contact areas and characteristics between individual rocks, it is virtually impossible to predict or provide for a specific lateral resistance. With the above suggested procedures, the requirements for maintenance can be reduced, however, provisions for future maintenance must be made. If any movements occur, they must be promptly corrected. Site Drainage No groundwater was observed in our test pits. However, it has been our experience that groundwater levels change significantly Earth Consultants, Inc.