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<br /> November 1 l,2011
<br /> MSE Project No.: 11-0195
<br /> File No.: OOOl39-11000-1 �
<br /> City of Orono Permit No.: 2011-01336 MSE
<br /> Mortariess Systems Eogineering
<br /> To: Mr. AI Seran AnSRWDesignFiim
<br /> Subject: Response to Memorandum (Project Review Comments) by Stantec dated 1 1-3-
<br /> 11, Proposed Segmental Retaining Wall (SRW), Seran Residence, 4099
<br /> Highwood Road, Orono, MN
<br /> Reference: Design Cross Section, Seran Residence, 4099 Highwood Road, Orono, MN, by
<br /> MSE, dated October 24, 2011
<br /> , Menzorandum(Project Review Comments)by Stantec, dated 11-3-11
<br /> ' Mortarless Systems Engineering, Inc. (MSE) has prepared this letter responding to the subject
<br /> project review comments of the reference Menaoranduna. Specifically, MSE is responding to
<br /> comment items 3, 5 and 6.
<br /> With regard to comment item 3.,the proposed SRW has a design bearing pressure of<1300 psf. It
<br /> is MSE's understanding that many governing codes, including the 2007 IBC, do not require soil
<br /> investigations when loads are less than 1500 psf, and allow for a presumptive allowable bearing
<br /> capacity of 1500 ps£ As such,MSE believes a geotechnical report is not required.
<br /> With regard to comment item 5., global stability, the overall stability of the soils surrounding(but
<br /> not including)the reinforced soil mass of an SRW, is typically a concern when the proposed design
<br /> of an SRW includes large loads(> 1500 ps fl and/or surcharges imposed on relatively steep sloping
<br /> conditions. The proposed subject SRW geometries include flat grades on top of the walls, with no
<br /> surcharging, and predominantly flat grades in front of the walls, with some 3:1 (H:V)grades in the
<br /> short bend areas. [ It should be noted that grades are determined perpendicular to the wall face.] As
<br /> such, with consideration of the proposed loading (<1500 psf bearing pressure), and relatively flat
<br /> geometries,MSE believes a global stability analysis is not required.
<br /> With regard to comment items 6. a. thru c., MSE has obtained and visually observed a sample of
<br /> the proposed backfill material. Per ASTM D2488, Standard Practice for Description and
<br /> Identification ofSoils(Visual-Manual Procedure),the proposed backfill soil can be classified as a
<br /> brown silty fine to coarse sand with trace clay and fine gravel. Additionally, it may be assumed
<br /> based on this classification, and design reference charts (see Soil Mechanics, NAVFAC Design
<br /> Manaral 7.1, 1982), that the proposed backfill soil has a peak effective friction angle of at least 34
<br /> degrees. As such, MSE believes the proposed backtill meets or exceeds design specifications
<br /> for gradation,plast'c-� -and�<strength.
<br /> ���ESS�O� �
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<br /> President �*\ �I*�'
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<br /> �lF�f MINN�SO
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<br /> 325 Alliance Place NE,Rochester,MN 55906-3975� phone 507.535.3526 fax 507.529.2879 e-mail info@mortarless.net
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