2109 MCDOUGALL AVE 2018-01-02 MF Import

Geotechnical Engineering Evaluation 2109 McDougall Ave, Everett -Cobb February 14, 2007 RMI File No. 34206 Page 5 Permanent drainage systems should be installed for retaining walls (and subsurface walls). We recommend that these drainage systems consist of an 18-inch wide zone of clean (less than 3 percent fines), free -draining granular material placed along the back of the wall. Pea ,ravel is an acceptable drain material, or drainage composite may be used instead. We recommend that we be retained to evaluate the proposed wall drain backfill material for its suitability. The granular material should be placed up the back of the wall to within I foot of the ground surface. The top I foot should be a layer of compacted, low permeability soil to limit surface water infiltration and should be separated from the underlying free -draining material by a layer of plastic sheeting or building paper. A rigid perforated or sloped PVC drainpipe, having a minimum diameter of 4 inches, should be embedded in pea gravel or some other free -draining material and wrapped in a non -woven filter fabric at the base of the wall along its entire length. This drainpipe should discharge into tightlines leading to an appropriate collection and discharge point. Surface water drains and roof drains should not be connected to wall or fooling drains until there is at least I foot elevation difference below the fooling drains. Closure This report is issued with the understanding that it is the responsibility of the owner or his representative to ensure that the information and recommendations contained in this report are called to the attention of all concerned parties and incorporated into the plans and that the necessary steps are taken to see that the contractors or subcontractors carry out such recommendations in the field. We suggest that we provide observation of the earthwork phases of development. This should include grading, foundation construction and drainage installa,ton. Although we expect site geology, soil types, conditions, and distributions to be as discussed herein, some variations in subsurface conditions could occur. Should conditions other than those discussed above be encountered, the geotechnical consultant should be notified for review and comment. Additional or alternative recommendations may be required. USE OF THIS REPORT This report is the property of RMI ASSOCIATES LLC and has been prepared for Mr. Eric Cobb and his agents for use in planning and design of this project on this site only. The data and report should be provided to prospective contractors for their bidding and estimating purposes, but our report, conclusions and interpretations should not be construed as a warranty of subsurface conditions. At the tinne of this RMI ASSOCIATES LLC