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Report )5 7 1 9 sw Ql ye-LAJA-4-e-ir Tee 7ZZ Ait5 7223 Doi ( N V 5 July 28, 2022 David Weekly Homes 1905 NW 169th Place, Suite 102 Beaverton, OR 97006 Attention: Max Bondar Phases 1&2 Summary Letter Geotechnical Construction Observation Services River Terrace Crossing SW Woodhue Street and SW 150th Avenue Tigard, Oregon Project: DWHomes-1-03 We are pleased to submit this letter summarizing our geotechnical construction observation services for Phases 1 and 2 of the River Terrace Crossing development west of SW 150th Avenue in Tigard, Oregon. We prepared the following geotechnical documents related to the development: • GeoDesign, Inc. 2016. Reportof g , Geotechnical Engineering Services;River Terrace Area 10; 15445, 15475, 15515, 15685, 15745, and 15915 SW 150th Avenue; Tigard, Oregon, dated December 2, 2016. GeoDesign Project: Polygon-145-01 • GeoDesign, Inc., 2017. Addendum 1;Addition to River Terrace Area 10; Wellner Property; Tigard, Oregon, dated January 12, 2017. GeoDesign Projects: Polygon-153-02 and Polygon-145-01 • GeoDesign, Inc., 2018. Addendum 2;Additional Seismic Refraction and Test Pits;River Terrace Area 10; Tigard, Oregon, dated March 13, 2018. GeoDesign Project: Polygon-145-01 • GeoDesign, Inc., 2018. Addendum 3; Prior Geotechnical Construction Observation and Updated Seismic Parameters;River Terrace Area 10; Tigard, Oregon, dated July 21, 2021. GeoDesign Projects: DWHomes-1-01 and Polygon-145-01 • GeoDesign, Inc., 2017. Memorandum; Culvert Crossings; River Terrace Area 10; SW 150th Avenue; Tigard, Oregon, dated March 22, 2017. GeoDesign Project: Polygon-145-01 • GeoDesign, Inc., 2017. Memorandum;Retaining Wall Recommendations; River Terrace Area 10;SW 150th Avenue; Tigard, Oregon, dated October 27, 2017. GeoDesign Project: Polygon-145-06 9450 SW COMMERCE CIRCLE,SUITE 300 I WILSONVILLE,OR 97070 I www.NV5.coM I OFFICE 503.968.8787 • GeoDesign, Inc., 2018. Memorandum;Storm water Pond Revised Grading; River Terrace Area 10;SW 15Oth Avenue; Tigard, Oregon, dated April 25, 2018. GeoDesign Project: Polygon-145-06 • GeoDesign, Inc., 2019. Memorandum; Lock+Load Retaining Wall Design - Revision 2; River Terrace Crossing(Area 10);SW 15Oth Avenue; Tigard, Oregon, dated February 28, 2019. GeoDesign Project: Polygon-145-06 • GeoDesign, Inc. dba NV5, 2021. Addendum 1; Updated Details and Revised Grading Plan; River Terrace Area 10;SW 15Oth Avenue; Tigard, Oregon, dated March 8, 2021. GeoDesign Project: Polygon-145-06 • GeoDesign, Inc. dba NV5, 2021. Addendum 2; Updated Wall Table;River Terrace Area 10; SW 15Oth Avenue; Tigard, Oregon, dated March 17, 2021. GeoDesign Project: Polygon-145-06 • NV5, 2021. Addendum 3; Prior Geotechnical Construction Observation and Updated Seismic Parameters;River Terrace Area 10; Tigard, Oregon, dated July 21, 2021. Projects: DWHomes-1-01 and Polygon-145-01 Construction for the River Terrace Crossing development began in July 2018, and we provided construction observation services for initial grading until March 2019. We continued to provide construction observation services for Phases 1, 2, and 3 on August 18, 2021, after which we have conducted site visits on 186 days to date, with multiple visits on some days. During construction we have observed site stripping, mass grading, utility trench backfill, retaining wall backfill, road subgrade and base rock preparation, and asphalt concrete (AC) placement. We used a Troxler 3430 nuclear density gauge to test compaction of the trench backfill, retaining wall backfill, fill for mass grading, and AC, and we observed proof rolls with on-site construction equipment. At your request, we have conducted density testing on every third lot of structural fill when prepared to finish grade. Based on our testing results and observations, we take the following exceptions to completion of Phases 1 and 2 and recommend the following: • Moisture conditioning and re-compacting the fill on Lots 49 - 56 • Removal or full grouting of clay pipe in the sidewall of Lot 80 • Removal of the top lift of backfill for retaining Walls 17.0 and 17.2 and replacement with crushed rock having a fines content of not more than 7 percent and compacted to 95 percent, as determined by ASTM D1557 • Placement of drain rock material around the drainpipe behind Wall 25.2 Members of our staff observed the geotechnical-related tasks identified above on an intermittent and on-call basis. The observations made during our site visits are summarized in daily field reports and a comprehensive list of nuclear density gauge test results, which are available for download via FTP file server and were provided to David Weekly Homes, Pacific Community Design, and other members of the design and construction teams. To the extent observed and tested,the construction activities outlined above for River Terrace Crossing were conducted in general conformance with the intent of the project plans,the specifications, and our geotechnical recommendations. Footings for the residences on all lots at the site can be designed and constructed in accordance with the following recommendations. N V 5 2 DWHomes-1-03:072822 The minimum continuous wall and spread footing widths should meet governing code requirements. The bottoms of perimeter footings should extend at least 18 inches below the lowest adjacent grade. The bottoms of interior footings should be established at least 12 inches below the base of the floor slab. Footings should bear on undisturbed, firm native soil or on structural fill overlying native soil. We recommend an allowable bearing pressure of 2,000 pounds per square foot. The above value represents a net bearing pressure;the weight of the footings and overlying backfill can be ignored in calculating footing sizes. The recommended allowable bearing pressure applies to the total of dead plus long-term live loads and may be increased by one-half for short-term loads (such as those resulting from wind or seismic forces). Based on our analysis and experience with similar soil,total post-construction settlement should be less than 1 inch, with differential settlement of less than half of the total between adjacent foundation elements. In wet weather, we recommend placing a sufficient amount of crushed rock (typically 2 to 4 inches)to prevent disturbance to the foundation subgrade. The contractor is responsible for the construction sequencing and methodology for footing excavation and construction. Consequently, the actual amount of rock placed to protect foundation subgrade from disturbance in wet weather should be selected by the contractor. Rock used to protect the subgrade during wet weather should cover the foundation bearing surfaces and be compacted until "well keyed." Any foundation subgrade soil that is disturbed should be removed before crushed rock is placed and/or foundations are poured. Lateral loads on footings can be resisted by passive earth pressure on the sides of the structures and by friction on the base of the footings. Our analysis indicates that the available passive earth pressure for footings confined by structural fill or footings constructed in direct contact with the undisturbed native soil or structural fill is 350 pounds per cubic foot (pcf). Typically, the movement required to develop the available passive resistance may be relatively large; therefore, we recommend using a reduced passive pressure of 250 pcf. Adjacent floor slabs, pavement, or the upper 12-inch depth of adjacent unpaved areas should not be considered when calculating passive resistance. A coefficient of friction equal to 0.35 may be used when calculating resistance to sliding. ♦ ♦ ♦ N r 5 3 DWHomes-1-03:072822 We appreciate the opportunity to work with you on this project. If you have questions concerning the information provided, please call. Sincerely, �S� .G PR fi�cts�o NV5 ir' p r 2, REGON co Zane M. Rogers, P.E. 4f/CHAO. Q`� Project Engineer = {„..._ z EXPIRES: 12/31/22____ ll 7 , „���p PRpcF Sha . Dimke, P.E., G.E. 0 4�G I NeF,Qssro2 Pri pal Engineer j, 63114PE r cc: Patrick Espinosa, Pacific Community Design (via email only) OREGON� ' Jeff Hellings, Pacific Community Design (via email only) °ch 14 2°0 t, �'%11/N p`M1. ZMR:SMD:sn One copy submitted(via email only) EXPIRES: 12/31/23 Document ID: DWHomes-1-03-072822-geol-summary ©2022 NV5. All rights reserved. N V 5 4 DWHomes-103:072822 1 "CROSSING AT BULL MOUNTAIN" 6-777 s'w IS lveck.k-Ar L 720 `der- �72Z� HUB AND TACKCK CERTIFICATION SE 1/4 SEC. 8, T 2 5, R 1 W, W.M. CITY OF TIGARD, WASHNGTON COUNTY, OREGON 2023 -0017 SURVEYED JUNE 5, 2023 / / l PREPARED FOR: PACIFIC LIFESTYLE HOMES 11815 NE 99TH ST., SUITE 1200 VANCOUVER, WA. 98682 I 119 I �I N ? �' f Cn d'.. N 79•93, } N89'55'53"E 94.49' 1 i 20.51, a. I . t=5.11` co I 4) ^ _--7 I ( e of L w R ltl 0 ) W W TRACT A �d 120 0 Ni 0 I to f 1 21,23' - - 20__1 .04' r'`- N 4 Z L o w I 4 22,41.-' f S89.55'53"W 97.00' f ' 1 -20.55. w U Ptit A D U' W CC - 8 121 cn a c 'O `c I O O REGISTEREDI m PROFESSIONAL 6.00' UTILITY—� UTILITY ° LAND SURVEYOR I EASEMENT 122 O < OREGON a JULY 9, 2002 a TRAVIS C. JANSEN4111161 j 57751 J o RENEWS: 6/30/2025 = I, TRAVIS C. JANSEN, A REGISTERED PROFESSIONAL LAND SCALE 9. SURVEYOR IN THE STA IL OF OREGON, HEREBY CERTIFY THAT 30 0 15 30 I HAVE ACCURATELY SURVEYED AND STAKED THE ' o FOUNDATION ENVELOPE FOR LOT 120 OF "CROSSING AT BULL 1 INCH = 30 FEET 8 MOUNTAIN". .' DRAWN BY: MJL DATE:06/05/23 PACIFIC COMMUNITY DESIGN REVIEWED BY: T2 DATE:06/05/23 �06-001 PLANNING ENGINEERING SURVEYING PROJECT NO.: (503) 941-9484