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Correspondence (7) • t. October 20, 2008 rerracon Consulting Engineers & Scientists 12400 SE Freeman Way, Suite 102 Portland, Oregon 97222 503.659 3281 WinCo Foods LLC Ph 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 '/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 More Than 95 Offices Nationwide WinCo Foods Store #23 1 Frracon 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. ' �o PR OFFS � Sincerely, '< S' / O* TERRACON CONSULT ' III. .� 78792P 0, OREGON ry p" Andrea F. Kuehnel, P.E. ' Kris : . Hauck, P.E. 9,y A 1a �� Senior Engineer �� � Office Manager Distribution: Addressee 1 3 WinCo Foo E�.S�' I i (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