1330 ROCKEFELLER AVE MEDICAL OFFICE BLDG BASE FILE 2018-01-01 MF Import

i � Coffman VFT Engineers . I , �� --�� Apri125, 198R II Un� �J � � 'il ,� l�' I �J � u U APR 2 �i 1988 '--� ................... _ ciiv o� cv��r� Mr. Dennis Forsyth Publ�c '�v��is �ept. The NBBJ Group 111 South Jackson Street Seatde,Washington 98104 Project: Everett Medical Office Building Pazking Lot Everett,Washington Subjxt Retaining Wall Dear Dennis: At your request,we have invesrigaud the structural integrity of the existing ntaining wall reladve to the revised usage of the area ie back of the wall (namely, being converted to a � pazldng lot). ` As you will recall at the time the bid documents were prepazed,we had not(and still have not) seen any drawings and/or calculations for the original design of the wall. Consequendy, we indicated a strengthening method which we envisioned as a worst case (from both a dme and money point of view)subject to a more thorough investigadon aftor � contract award. � On Aprii 5, 1988, Gaffney Construcaon performed an "x-ray" evaluation of the wall reinforcement, subsequendy confirmed by exploradon through selecdve demolidon. It would be reasonable to assume that the roinforcement pattem discovaed would bc unifomi throughout the length of the wall. That reinforcement has proven to be: No. 5 Bars @ 8" o.c, vertically (flexural) with every other bar terminated 2' 6" from U�e top of the wall and No. 4 Bars @ 12" o.c. horizontally (temperature/shrinkage). The physical properties of�tie wall are: approximately 150'0" long; 12-inch thick throughout its 10' 6" height with 3 1/2-inch square drain holes @ 4' 0" o.c. (note that the drain holes have been covered by tennis court paving); the reinforcement has been placed on the tension (backfill) side of the wall with 1 1/2" of cover. A visual inspecdon by Gaffney Consavcdon has revealed no signs of distress in the wall. A soils invesdgadon performed before awazd of contract has revealed soils of a very stable and dry nature. We compared the above informaaon to the properties required by the Concrete Reinforcing Steel Institute (CRSn handbook(1984 edidon)for canalevered retaining walls using what we feel to be conservadve criteria(Class "C" soil with sloping backfill). Using this criteria the flezural steel is well W�ithin guidelines and the wall thiclmess and temperature/shrinkage steel is marginal; however, the service life and condidon of the wall lead us to conclude that they aze sadsfactory. Please note that there has been no discussion of the existing wall footing; to examine the wall foodng would require demoliaon of a portion of the exisdng tennis courts which aze not the property of this Owner. We believe that it is a sound �m o�rve vrr•eurte wo•se�me vM uim�ieu•t:oe�ezw�ir 55a SEVENiN ME•SUIiE 100•ANLMORr1GE AK 9950�•(90])2)6665�