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Report 557 5 5 A/ 62c/4: L1 41$ 7 — ) /O'/ • Construction Inspection Pe ction & Related Tests Carlson Testing,.. Inc. l - - • ._.. Geotechnical Consulting P.O. Box 23814 , �. Tigard, Oregon 97281 April 22, 1 998 Phone (503) 684 -3460 FAX (503) 684 -0954 CTI #97-G1396 . F _ n j • Matrix Development Corporation ' f O J 6900 SW Haines Street - Suite #200 tir4 /O Tigard, Oregon 97223 -2514 PARTIAL FINAL REPORT OF EARTHWORK OBSERVATION AND TESTING APPLEWOOD PARK II LOTS 15 THRU 29, 39, 45 THRU 48, 56 THRU 59, & 77 THRU 79 TIGARD, OREGON Carlson Testing Inc. (CT!), has conducted on -call inspection services for the earthwork at the above residential development located off SW Hall Blvd. and SW Settler ST. in Tigard, Oregon. Although not all of the lots within the subdivision are ready for final inspection, the developer has requested this letter summarizing our observations and testing during construction of the above referenced lots. The attached plan indicates the lots being reviewed for the partial final letter. This letter provides recommendations for foundation design and soil guidelines during construction of the single - family homes on the lots in question. SITE PREPARATION AND FILL PLACEMENT Based on our field observations and density test results, no engineered fill has been placed on any of the lots with the exception of Lot 77. From our conversation with Matrix Development, we understand the subject lots were left near original grade. CTI visited the site on April 21, 1998, to review the existing soil conditions. From our observations, the majority of the lots are covered with approximately 12 to 24 inches of uncompacted trench spoils, strippings and /or water softened soils. HOUSE EXCAVATION GUIDELINES The surface of the lots in question are covered with an roughly 12 to 24 inches of uncompacted or water softened material. If the developer wishes to warrant the excavation depth to suitable foundation bearing soil, we recommend that a minimum depth of 2 feet be used. Some slightly deeper excavations may be required in isolated areas. If excavated material is spread around the lot and is expected to support appurtenant structures such as deck footings and sidewalks, it should be placed, compacted, and tested as engineered fill. FOUNDATIONS The proposed one- to three -story residential buildings will likely be founded on shallow spread footings bearing on competent native soils or engineered fill. Spread footing design and construction should generally conform to UBC Chapter 18 and /or Chapter 4 of the CABO One and Two Family Dwelling Code, except where we specifically recommend otherwise. For protection against frost heave we recommend that spread footings on nonexpansive soils have a minimum final embedment depth of 12 inches for exterior grades on level ground; however, it is likely that footing excavations will be significantly deeper to achieve adequate bearing soil due to the soft surface soils. The recommended minimum widths for continuous wall footings are tabulated on the following page: CTI #97-G1396 Applewood Park II Page 2 Minimum Width for No. of Stories Continuous Footing (floors supported) (in) 1 -story 12 2 -story 15 3 -story 1 g The allowable bearing pressure can be taken as 1,500 lb /f for footings bearing on competent native subsoils or engineered fill. The recommended maximum load is 15 kips for column footings. For heavier column loads and masonry chimneys, a Soil Engineer should be consulted. The coefficient of friction between on -site soil and poured -in -place concrete may be taken as 0.35 for native soils and 0.40 for engineered fill. The maximum anticipated total and differential footing movements are 1 inch and 3 /4 inch, respectively, over a span of 20 feet. If requested, CTI can provide inspection services to verify that suitable foundation subgrade is exposed prior to placement of concrete. • CTI #97-G1396 Applewood Park II Page 3 CLOSING AND LIMITATIONS Our reports pertain to the materials tested /inspected only. This letter should be made available to each builder in the development; however, information contained herein is not to be reproduced, except in full, without prior authorization from this office. This letter should not be construed to relieve or lessen the responsibility of the contractor or owner's site representative for this site work, but is provided for the minimum required governmental assurance. Our support was given on an as- needed basis as requested. If conditions are encountered during foundation excavation which differ from this report, then the developer (Matrix Development), the contractor (Schmidt Excavating) and CTI should be allowed to review the condition before corrective actions are taken. Corrective work performed by the builder without notifying the above parties will be interpreted as an acceptance of the conditions encountered. Respectfully submitted, CARLSON TESTING, INC. F - NG NE s si o 4 4. � 9 14743 OREGON 4N 23..89 • ` ` D. 10 ���• (.7y). —3c7— Brian D. Leach, E.I. James D. Imbrie, P.E. Engineering Associate Principal Engineer cc: City of Tigard Schimdt Excavating • 10 , _ 1- 4i I �__ SS7 u D U _ ii I n r 4 _ —.._ — - - -- -- 1'c \ -- - - -- I I — J u - : __ S. W. 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