1505 112TH ST SW 2018-01-02 MF Import

DEC 22 '92 08,26 EARTH COHSULTAHTS WXY40"VIA P.2 Earth Consultants Inc. .,.n1viW ,IYO'RI,. rn..6LL.lI,M,�.,v..II15f.,.Y. December 21, 1992 11-5813 Wells Development Corporation P. O. Box 518 Bellevue, Wa. 98009 Attention: Mr. Tom WeJls Subject: Proposed Rockery Waits Vehicle EmLrsion Testing Site #31 Everett, Washington Reference: Barth Consultants, irtc. Ototahnical Engineering Study P,-5813 Dated July 27, 1992 Dear Mr. Wells: After a review of the site plan provided to us from Bush, Rood and Hitchings, we understand thst a proposed rockery wall will be constructed at the northwest side of the site, around a proposed stormwala biofiltration pond. We understand that the rockcrles will range from three and one-half to seven feel in height, and will be constructed along earthwork cuts into the existing medium dense native soils. To achieve the desired grades, maximum fills of ILtee feet will be required along the rockeries at the cast side of the proposed pond. We suggest using five - man rocks (48-54 inches) at the lower four foot sections of the rockery will, and tout -man rocks (36-48 inches) above sections of the rockery wall greater than four feet in height. We also suggest that the bottom rocks of the wall be embedded at least eight= inches below grade. The rockery will help to protect the cuts at the lop of the pond from erosion and has not been designed to retain fills greater than four feel in height. The rockery should be constructed in accordance with the attached Associated Rockery Contractors (ARC) guidelines, by a qualified rockery contractor. Due to the proposed construction of rockery walls along the top of the 3H:IV slopes, at the blofilttation pond, and the existing condition of the on -site soils encountered during the time of [[lour gllnooltlrpd' linnieal study, we recommend that the side slopes of the pond be protected from erosion I UJ LS l�r� U 1'1 IS ti"nr „f lhl lu!louiny into the design and rnnitnlclion cd Ihr pond W-On 2 2 Uldet. f erl.'..t C I: It'll