Correspondence October 20, 2008 rerracon
Consulting Engineers & Scientists
12400 SE Freeman Way, Suite 102
Portland, Oregon 97222
Phone 503 659.3281
WinCo Foods LLC Fax 503.659.1287
650 North Armstrong Place www.terracon.com
Boise, Idaho 83704
Attn: Mr. David Van Etten, Vice President
Re: WinCo Foods Store #23 — Parking Lot Improvements
7501 Dartmouth Avenue
Tigard, Oregon
Terracon Project No. 82081002
Permit # SIT - 2008 -00005
Terracon Consultants, Inc. provided geotechnical observation during construction of the parking
lot improvements for the WinCo Foods Store addition project in Tigard, Oregon. A
representative of Terracon was on -site periodically to observe the construction. Our site
observations have been documented in daily field reports, and a brief summary follows.
Subgrade and Structural Fill Observation and Testing
Where exposed, we observed and tested the pavement subgrade areas typically using a T-
handled probe. Limited areas that were observed to be loose or disturbed were re- compacted
by the contractor. An area at the southwest portion of the parking lot required overexcavation of
about 1 /2 to 1 foot of soft organic soil. At this location, the contractor placed geofabric over the
subgrade and backfilled with imported crushed rock fill. Based on our observations, it is our
opinion that the subgrade areas observed were prepared in general accordance with the project
specifications
A Terracon representative performed observation and testing of structural fill materials placed
for pavement base course and utility trench backfill materials. The base course materials
typically consisted of imported crushed rock fill. The fill was compacted with either a smooth -
drum vibratory roller or vibratory plate compactor. The utility vault at the southwest portion of the
parking lot was backfilled with screen sand with crushed rock base course placed near finished
grades. The backfill for the vault area was compacted using a hoe -pack attached to a trackhoe.
Based on our testing and observations, it is our opinion that the structural fill observed was
placed and compacted in general accordance with project specifications.
Asphalt Observation and Testing
A Terracon representative was on -site periodically for observation and testing of hot mix
asphaltic concrete (HMAC) placement. The thickness and temperature of the HMAC was
observed during placement, and the compaction of the HMAC was tested using a nuclear
Delivering Success for Clients and Employees Since 1965
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WinCo Foods Store #23 1 R!rrac ®n
Tigard, Oregon
Project No. 82081002 /Permit #SIT- 2008 -00005
October 20, 2008
density gauge. The test results are at or above the typical acceptable range of 92 percent of the
theoretical maximum density (TMD) value that was provided by the asphalt supplier.
Therefore, based on our testing and observations, it is our opinion that the HMAC materials
observed were placed and compacted in general accordance with project specifications.
We trust this letter meets your current needs. Please do not hesitate to contact us should you
have any questions.
P PROFe
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Sincerely, c %*
TERRACON CONSULT + Ifs. .9
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_ OP..EGON � o° v : .Hauck P.E.
Andrea F. Kuehnel, P.E. '9 lv Kris
Senior Engineer ���� BE v
Office Manager
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Distribution: Addressee (1) P)
WinCo Foo EiS l* d (1)
Stapley Engineers — Greg Leishman, E
Bruce W. Peterson, NCARB — Lee Lizama, AIA
City of Tigard — Building Permits — Walter Bennett IV (1)
ESI Construction — Richard Brien (1)
ESI Construction — Mike Tsu (e -mail only)
2