Report 03 /01/05 TUE 13:11 FAX 503 670 9147 CA1(LbUN 1t*.t .
Carlson Geotee: _iical Main °ffic°� Bend. Rend Office
P.O. Box 23814 ,...., Hudson Awe , NE P.O. Banc 791e
A G 2 otech Ot Cartson Tasting. Inp. (503) 684.3 Phone (503) 89-1252 Phone (54 ) 330 -9155
Goffichnir�l Consulting Phone
Construction Inspection and Related Tasts FAX (503) 670-9147 FAX (503) 589.1309 FAX (541) 330-9163
Final Summary Letter
June 14, 2004
/V. STz.c63 3
Mr. Mark Hansen �
Derek L. Brown & Associates, Inc. / c' 7> -(-1 L.. v{
9500 SW Barbur Blvd., Suite 220
Portland, Oregon 97219
Re: Final Letter of Geotechnical Observations
Hawks Beard Townhomes
SW Hawks Beard Street
Tigard, Oregon
CGT Project G0202050.A
Carlson Geotechnical (CGT) served as geotechnical 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 investigation 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-time 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 construction, 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 silt 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 rock on May 2, 2003. The roadway
03/01/05 TUE 13:12 FAX 503 870 9147 t:AXL,viv izai imi
Hawks Beard Townhomes
Tigard, 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 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, ` .a: `'.;
CARLSON GEOTECHNICAL : • ; t'•=
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