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Correspondence 1‘ S Fr - Geo Engineers October 24, 1995 Consulting Engineers and Geoscientists Offices in Washington, PacTrust Oregon. and Alaska 15115 Southwest Sequoia Parkway, Suite 200 Portland, Oregon 97224 Attention: Mr. Ken Grimes Rockery Evaluation Pacific Corporate Center - Portland Clinic Tigard, Oregon File No. 2361 - 011 -P36 The primary functions of a rockery are to retain small local slumps and to prevent slope surface erosion. If properly designed and constructed a rockery will also increase the stability of a slope. This was the intent of our previous rockery design for the project (dated August 8, 1994). As stated in our memorandum to Mr. Jim Funk at the City of Tigard dated October 18, 1995, these designs are appropriate for the Pacific Corporate Center from Carmen Drive north to Bonita Road. These designs allowed for permanent wall heights up to 12 feet high battered at a 1H:5V. However, it is possible to construct temporary rockeries to heights greater than 12 feet at this site. As you requested in your facsimile dated October 20 we have evaluated rockeries with a temporary exposed height of up to 16 feet adjacent to the Portland Clinic at the Pacific Corporate Center. We understand that this height will be necessary for a period of a few months during construction of the Portland Clinic, and that after a few months backfill can be placed against the lower four feet of the exposed rockery and the exterior wall of the Portland Clinic. This will result in a permanent exposed rockery height of 12 feet, as per our previous recommendations. In order to achieve an adequate factor of safety for the temporary 16 foot exposed wall height, we recommend the following design features be added to our original rockery details: GeoEngineers. Inc. 7504 SW Bridgeport Road Portland, OR 97224 Telephone (503) 624 -9274 Fax (503) 620 -5940 • Printed on recycled paper. --. —. - PacTrust October 24, 1995 Page 2 1) The minimum rock dimensions should conform to the following: Rock size (in) Distance below top of rockery (ft) 66" 17 57" 15 • 50" 13 44" 11' The distances include an allowance for one foot of embedment below the ground surface. As per our 8/8/94 recommendations 2) The rockery should be battered at 1 H:4V. ` a / In addition, the exterior wall of the Portland Clinic should be designed for the lateral earth pressure of a 56 pcf equivalent fluid and wall backfill should consist of granular material with less than 5% passing a # 200 sieve. These values apply to wall cuts which expose soils with the strength of medium stiff silts or better, as encountered in our explorations at the site. . O ► We hope these recommendations satisfy your needs at this time. If you have any questions, please do not hesitate to give us a call. Yours very truly, . • ���D PR OF Fs�, ,G I N z GeoEngineers, Inc. �•► 16,073 OREGON 14 21. ON RONOON‘v Don Rondema, P.E. Geotechnical Engineer I Expires 12/31/9C 1 Scott V. Mills, P.E. Principal DLR:SVM: Document ID: 23610111.rky • cc: Mr. Dennis Woods Mackenzie Engineering G e o E n g i n e e r s File No. 2361 -011 -P36 09/30/96 MON 14:51 FAX 503 820 5940 GEO ENGINEERS tj001 5 17 ertY q Geo Engineers MEMORANDUM Portland TO: David Williams - Mackenzie Engineering Jim Funk - City if Tigard fax # 684-7297 FROM: Don Rondema, P.E. DATE: September 26, 1996 SUBJECT: Pacific Corporate Center - Portland Clinic This memo documents our evaluation of the proposed setback from the ascending slope located along the northeast corner of the proposed Portland Clinic. Based on my conversations with you and the sketch you provided it appears that an approximately 10 feet high 2.5H:1V slope ascends from the northeast corner of the building. This slope has a high factor of safety against shallow slope failures when protected from erosion. We understand that erosion control will be provided over the slope surface. We also understand that a perimeter foundation drain is to be located along this side of the building, and that it will be connected to a suitable discharge. We also understand that drain rock will be installed at the ground surface adjacent to the building to collect surface runoff and that this too would be routed to a suitable discharge. Based on this understanding and our experience with site soil conditions it is our opinion that this slope configuration meets the intent of UBC section 1806.4.2 and would qualify for approval under section 1804.6.6. If you have additional questions please do not hesitate to give me a call. PRO, / - a 4+1- .73 ` '9 9 • OREGON ti O °Cti'21, NO O RONO ��r P Expires 12/31/ 1 • • 09/26 16:45 1996 FROM: 503 620 5940 TO: 2473 PAGE: 1 09/26/96 THU 16:11 FAX 503 620 5940 GEO ENGINEERS 4-44 MACKENZIE g1001 Ceo= _ Engineers ngin rs MEMORANDUM Portland TO: David Williams - Mackenzie Engineering 1'2$''12$5 FROM: Don Rondema, P.E. DATE: September 26, 1996 SUBJECT: Pacific Corporate Center - Portland Clinic This memo documents our evaluation of the proposed setback from the ascending slope located along the northeast corner of the proposed Portland Clinic. Based on my conversations with you and the sketch you provided it appears that an approximately 10 feet high 2.5H: 1 V slope ascends from the northeast corner of the building. This slope has a high factor of safety against shallow slope failures when protected from erosion. We understand that erosion control will be provided over the slope surface. We also understand that a perimeter foundation drain is to be located along this side of the building, and that it will be connected to a suitable discharge. We also understand that drain rock will be installed at the ground surface adjacent to the building to collect surface runoff and that this too would be routed to a suitable discharge. Based on this understanding and our experience with site soil conditions it is our opinion that this slope configuration meets the intent of UBC section 1806.4.2 and would qualify for approval under section 1804.6.6. If you have additional questions please do not hesitate to give me a call.