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Report 03/01/05 TUE 13 :1l FAX 503 670 9147 e:Akelaun ataaan u Carlson Geotechnical OB° ° _ _ ° _ Geotechnical Banc 2 406 FA Ol1 Ave., NE • Bend P.O. Banc 7918 A a te c on of Carlson ul Telling, Ina. PI (� 684 Phone (543) 589.1252 Phone (1) 33 0 - 8Geotechnical Consulting C0f18trucyon Inspection and Related Teals FAX (503) 6749147 FAX (543) 589 -1309 FAX (541) 3349169 Final Summary Letter June 14, 2004 /i 5 1 2_0-0 3 - CPC 3 3 Mr. Mark Hansen d 9/ 44 Aj Derek L. Brown & Associates, Inc. 9500 SW Barbur Blvd., Suite 220 Portland, Oregon 97219 Re: Final Letter of Geotechnical Observations Hawks Beard Townhomees SW Hawks Beard Street Tigard, Oregon CGT Project G0202050.A Carlson Geotechnical (CGT) served as geote chnrcal Engineer -of- Record (EOR) for the Hawks Beard Townhomes project, located at the intersection of SW 130 Avenue and SW Hawks Beard Street in Tigard, Oregon. We performed a geotechnical tnvestigation of the site, the results of which were presented in our report of Geotechnical Engineering Services dated December 10, 2002, and performed geotechnical observation during construction. Our observations were completed on an on-call, part-lime basis between the dates of November 19, 2002 and July 17, 2003. This letter concerns observations and testing performed on Lots 1-6 since the final summary letter dated November 19, 2003 was sent out • Site Stripping: Prior to constriction, the site contained surface vegetation in structural areas. Roadways and lots were stripped of vegetation between November 19 and 25 2002. Based on our field observations, the site was stripped of organic topsoil in general accordance with our recommendations. • Subgrade Conditions: After stripping had been completed, the site subgrade soil was cement treated for planned construction activities in the winter. Based on our field observations, the subgrade soil has been prepared in general accordance • with our recommendations. • Roadway Fill Placement and Compaction: Up to 2 feet of fill was placed and compacted on roadways in the southeast corner of the site. CGT conducted 6 in- place relative compaction tests on the native brown sift fill. Based on our field observations and in place density testing the native sift fill for roadways was placed and compacted in general accordance with our recommendations (92 percent of ASTM D- 1557). • Roadway Aggregate Base Rock: CGT conducted 12 In -place relative compaction tests on the roadway aggregate base rode on May 2, 2003. The roadway 03/01/05 TUE 13:12 FAX 503 670 9147 VA9LbuNr r Ira, ._____. _ Hawks Beard Townhomes Tiga►d, Oregon June 14. 2004 aggregate base rock was prepared in general accordance with the recommendations given by the City of Tigard (95 percent of AASHTO T -99). • Roadway Pavements: Asphalt was placed on the South Alley, North Alley, Hazelwood, Briarwood, Woodridge, Huntington, and Hawks Beard on May 13, 2003. CGT conducted 17 in-place relative compaction tests on the asphalt Test results ranged from 91 to 93.1 percent of ASTM D -2950. • Lots: Based on our field observations, lots 8 through 13, and lots 1 through 3 were cut and are on native silt. The remaining 53 lots are on structural fill up to 3 feet deep. Based on our observations and in -place relative compaction testing, lots 1 through 62 have been prepared in general accordance with our recommendations. • Foundation Bearing Surfaces: Foundation bearing surfaces were not prepared at the time of this report; therefore, we have not observed any of the foundation subgrade soils for the proposed residences. ... ; . •• - :,--- - - ; ... .. - : . : pouring—eonerete. We understand that the City of Tigard will not require individual lot foundation subgrade observations. • Utility trench backfill compaction. CGT conducted 28 in -place relative compaction tests on utility trench backfill material for the sanitary sewer and storm sewer trenches. Based on our density testing, the utility trenches backfill has been compacted in general accordance with the recommendations given by City of Tigard (95 percent of AASHTO T -99). Based on our observations, as documented in our field reports, and to the best or our knowledge, within our scope of work, the above geotechnical summaries accurately reflect our observations. Our services were provided on an on -call basis, in which we relied on the contractor to contact our office for the scheduling of our services. We cannot be held contractually responsible for those items, if any. that we did not observe or test. Sincerely, = ' -= - CARLSON GEOTECHNICAL ; ':.t: '; ; Y 1'v�G�r11GW "' -.�.,- U1 .AI, • •technical Staff • tito n n e M. 'eme P.E. + : .5: ty.3� cxe pal G; 'technical Engineer Doc ID P :IGEOTECHIPROJECTS12002 PrajedsiHavvics Beard Tawnhornes - cos 1Final Letter.DOC Carlson Geotechnical Page 2 of 2