5505 BROADWAY RECORDS STORAGE ONLY 2016-01-01 MF Import

Battermann Geotechnical Consulting 1•,� �� July 25, 2007 r►rr► :. .r:� PLLC Project No. 06048 Mr. Robert Halverson 3519 Wetmore Avenue,Apt. B Everett,WA 98201 Subject: Addendum to Subsurface Exploration and Geotechnical Engineering Report Halverson Property 56xx Broadway Everett, Washington The following addendum letter is a supplement to our Subsurface Exploration,Geologic Hazards, and Geotechnical Engineering Report for the Halverson Property dated October 4, 2006. Where in conflict,the recommendations in this letter supersede the recommendations contained in that report. The original plan for development of a single family residence on this site required the construction of a 20 to 25 foot high retaining wall in order to provide a building pad high enough on the property that an access driveway off of Broadway Avenue was feasible. In the intervening months,it is our understanding that you have had meetings with both your neighbors to the north and with the City of Everett. The current proposal is to develop a building pad by construction of a structural fill that will also benefit and extend onto the neighbors property. From a geotechnical engineering standpoint,this is a much preferred alternative than construction of the large wall. Battermann Geotechnical Consulting,pile is in full support of the grading plan to fill the old erosional ravine between the two properties with structural fill. The recommendations in this addendum letter address the geotechnical engineering considerations necessary to complete the proposed grading. The existing fill soils and loose,slope colluvial soils will need to be removed from the areas to receive structural fill.The non-organic portions of these materials may be re-used in the new structural fill. The subgrade soils shall be in a medium dense condition prior to placing new fill. The existing culvert under Broadway Avenue should be extended beyond the planned toe of the new structural fill body. The new culvert should be bedded on a layer of pea gravel and then may be filled over during the placement and compaction of the new fill. The culvert should be set to discharge on a rock splash pad comprised of minimum 12 inch diameter quarry spall rock that is embedded into native subgrade so the top surface of the rock is at existing grade. The rock pad should be a minimum of 4 feet wide and 6 feet long. Construction of the new fill should start at the toe of the slope and work up the slope. The fill shall be placed horizontally. Fill soils should be placed in lifts not to exceed 10 inches thick. Each lift shall be compacted to a minimum of 95 percent of the modified Proctor value of the fill soil. Density testing should be performed to verify suitable compaction of the fill soil. As the BGC, PLLC 14267 209th Avenue NE Woodinville, WA 98077 (425) 273-5062