Report •
POg 23 5:52PM SR !sign LLC 5 459 - 6553 p.
eived ak . r: Au 201)4 I" :.I;;Pr1 S.tat for I f c
Rug 23 04 12:10p . Derek Brown & Assoc. (9711 233 -0071 p.2
06/23/04 NON 10:56 FAX 503 870 9147 CARLSON TESTING X001
C arlson P.O. Warn PO. °
A
T�,rd, Oregon 07281 seism. OR 97301 Rend. OR 97708
oioc n of Censer Tnpnp. Wnc. Phone (503) 6643480 Phone (503) 589 -1252 Phone (541) 3304155" Consire vicar Can FAX (50331 414T FAX (603) 509 - 1300 FAX (611)3304143
onslNe(wn b�pltedOn o^ one Related Teets
Final Summary Letter
August 23. 2004 (i°
Mr. Mark Hanson
Derek Brown 8 Associates, Inc. a-0 9500 SW Barbur Boulevard 5 �3 -
Portland, Oregon 97219 c-0 P/
Re: Final Letter of Oaotechnical Compliance
Bonita Town Home Subdivision
Southwest Fenno Creek Drive & Southwest Bonita Road
Tigard, Oregon
CGT Prbject G0302094.A
Carlson Geotechnical (CGT) served as geotechnical engineer -of- record (EOR) for the Bonita
Town Home Subdivision project in Tigard, Oregon. As geotechnical engineer, we performed a
geotechnical investigation of the site, the results of which were presented in our Report of
Geotethnkal Engineering Services dated April 24. 2003. observation ormed geotechnical
construction observation services during construction - Our
on -call, part time basis during the months of April through July 2004.
Foundation bearing surfaces were not prepared at the tf ne of residences. CGT
this report; therefore, we observe
observed any of the foundation subgrade soils for the prop
the foundation subgrades after they have been excavated to subgrade elevation, and prior to
pouring concrete.
Copies of our field reports have been forwarded to you, and are available in our office. We
performed the following observations during construction:
• Site stripping: Based an our field observations, the site was stripped of organic
topsoil in general accordance with our recommendations.
• Site grading: Based on our field observations as of our last visit dated 7120/04.
permanent slopes at the site have been graded to a 2H:1V (2 horizontal
:1 vertical) gradient or less in general accordance with our recommendations.
• Lot structural fill: Based on our observations. the lot fills placed at the site that we
observed were prepared in general accordance with our recommendations.
•
•
110g 23 5:52PM SR sign LLC 5C 469 - 8553 p, 3
eio• emu:: _- opr.� _ iiSFr Fa : =tin L_. .. 3
'Au6 23 04 12: 10p Derek Brown 6 Assoc. (971) 233 -0071 p.3
08/23/04 MO? 10:50 FAX 503 870 6147 CARLSON TESTING ■002
Final Summary Letter
Bonita Town Nome Subdivision
Tioad. Orrgon
G0302094.A
August 23, 2004
Retaining wall subgrade and backlit!: Based on our observations, the retaining
wail subgrade soils that we observed have been prepared In accordance with our
recommendations.
Based on our observations during backfidllng. the two Look and Load type walls
located at the northeastern portion of the site had been bacidifed with a
combination of Imported crushed aggregate and native sit materials. (Note: The
use of native materials as backfill was approved by David A. Halt, P.E. of David A.
Hatt Structural Engineering.) Imported crushed aggregate had been installed
within 3 feel of the back of the walls. Our density testing Indicates that this
material had been compacted to meet project specifications. Native silt materials
had been placed behind the crushed aggregate section and within the zone of get,-
grid reinforcement. We do have any records of COT performing density testing of
the sift material, with the exception of the 4-foot high retaining watt located at the
southwestern Quadrant of SW Weaver Way and Cattail South. Based on our
testing, this sift backfill section was compacted in general accordance with our
recommendations_ We understand that the slit backfll within the other retaining
wails at the site was Installed using similar equipment and methods. Consolidation
of the silt backfllls may occur if the sections of badfip were not prepared In general
accordance with our recommendations.
• Roadway structural tilt Based on our observations, the roadway tills placed at
the site that we observed were prepared in general accordance with our
recommendations.
• Roadway subgrade and base course: Based on our observations, proof rolling
and density testing (where applicable), the subgrade and base aggregate for the
roadways were prepared in accordance with project plans, specifications, and our
recommendations.
• Utility trench backfill compaction: Based on our observations and density
testing, with the exceptions noted below, the utility trench backfill that we observed
has been compacted In general accordance with proled plans, specifications, and
our recommendations.
We understand that density testing was not required for power line trench backfill
material within approximate 4.5 -foot deep trenches located parallel to existing curb
lines, which wIN bisect private driveways to the bts. We understand that this
material was compacted using similar equipment and methods as used In other
Pape 2 of 3
Carlson, Geolecttntcal
•
•
Atig 21 5:52PM SR ?sign LLC E - 469 -8553 p.4
rued ar. nL• 7 2004 l2:0001.I r: Si: t i.,n ... D -,'c❑ ; i -C
Aug 23 04 12:11p Derek Brown & Assoc. (971) 233 -0071 p.4
00/23/04 NON 10:57 FAX 503 870 9147 CARLSCN TESTING 0003
Fktar Summery Letter
Bonita Town Horne Subdivision
Tigard, Oregon
30302094.A
Augu 23, 2004
utility trench backfllling operations. Consolidation of this 4.5 -foot deep beckfill may
occur if this section of backfill was not prepared in general accordance with our
recommendations.
Roadway asphalt compaction: Based on our observations and da in general
testing,
both lifts of asphaltic concrete on site roadways have been
accordance with project plans, specifications. and our recommendations.
Based on our observations, as documented in our field report, and to the best of our knowledge,
within our scope of v. rk. the above geotechnical observations were completed in general
accordance with the recommendations provided in our report
Sincerely.
CARLSON GEOTECHNICAL
Br M. Wilcox, E.I.T.
Geotechnical Staff
1«
4.7; ITO 4
Jeanne M. Nernst, P.E.
Principal Geotechnical Engineer
Ooc IA: P.%OEOtCH PROJECTS12003 Projoc s1Bo l to Townhomes - COSURnal Latrer.00C
Carlson Gaotechnical Page 2 013