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Report West River Terrace Lot Location (continued) Lot# Street Address Permit# 65 13778 SW Sabrina Avenue MST2016-00239 66 13762 SW Sabrina Avenue MST2016-00240 67 13746 SW Sabrina Avenue MST2016-00241 68 13730 SW Sabrina Avenue MST2016-00101 69 13718 SW Sabrina Avenue Not available 70 13702 SW Sabrina Avenue Not available 71 13690 SW Sabrina Avenue MST2016-00242 72 13678 SW Sabrina Avenue Not available Construction for the West River Terrace residential development began in September 2015 and is ongoing. We observed stripping of Lots 55 through 59 and Lots 61 through 72 on October 1, 2015. We observed prepared lot fill from October 21, 2015 through October 23, 2016 and then from June 23, 2016 through July 6, 2016. We used a Troxler 3430 nuclear density gauge to test compaction of the fill. We observed the prepared lot subgrades on September 8, 2016. Some soft or loose areas were identified on September 8, 2016; however, they were outside the planned foundation subgrade areas. Members of our geotechnical staff observed geotechnical-related tasks identified above on an intermittent and on-call basis. The results of our site visits were summarized in daily field reports, copies of which have been provided to Polygon Northwest, Pacific Community Design, and members of the design and construction team. To the extent observed, the construction outlined above for subgrade preparation of Lots 55 through 59 and Lots 61 through 72 at the West River Terrace residential development have been completed in general conformance with the intent of the project plans, specifications, and our geotechnical recommendations. Footings for the residences on all the lots at the site can be designed and constructed in accordance with the following recommendations from our December 5, 2014 geotechnical report. Footings can be proportioned for an allowable soil bearing pressure of 2,000 pounds per square foot. A higher value may be possible, depending on the grading plan. The allowable bearing pressure is a net bearing pressure; the weight of the footing and overlying backfill can be ignored in calculating footing size. The allowable bearing pressure applies to the total of dead plus long-term live loads and may be doubled for short-term loads, such as those resulting from wind or seismic forces. Continuous wall and spread footings should be at least 15 and 24 inches wide, respectively. The bottom of exterior footings should be at least 18 inches below the lowest adjacent final grade. The bottom of interior footings should be placed at least 12 inches below the base of the floor slab. G EODESIGN? 2 Polygon-123-03:091316 For foundations designed in accordance with the recommendations provided above, total post- construction settlement is expected to be less than 1 inch and differential settlement between adjacent foundation elements is expected to be less than% inch, given the anticipated building loads for wood-framed residences. In wet weather, we recommend placing a sufficient amount of crushed rock(typically 2 to 4 inches) to prevent disturbance to the foundation subgrades. 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 subgrades from disturbance in wet weather should be selected by the contractor. Rock used to protect the subgrades 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 prior to the placement of crushed rock and/or pouring of the foundations. 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, pavements, 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. ♦ ♦ ♦ G EODESIGN= 3 Polygon-123-03:091316 We appreciate the opportunity to work with you on this project. If you have questions concerning the information provided, please call. Sincerely, GeoDesign, Inc. 0E0 PRO1c� 63114PE Reed S. Kistler, P.E. OIttGON Staff Engineer rah 14 2°�' /6/:1 6'1 EXPIRES: 12/31!17 awn M. Dimke, P.E., G.E. Principal Engineer cc: Chris Walther, Polygon Homes (via email only) Mike White, City of Tigard (via email only) RSK:SMD:kt One copy submitted(via email only) Document ID:Polygon-123-03-091316-geol-lots_55_59-61_72-rev.docx ©2016 GeoDesign, Inc. All rights reserved. G EODESIGN= 4 Polygon-123-03:091316 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, pavements, 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. ♦ ♦ ♦ We appreciate the opportunity to work with you on this project. If you have questions concerning the information provided, please call. Sincerely, GeoDesign, Inc. E,D PR0p4.,, 2 Reed S. Kistler, P.E. A ,. 63114PE Staff Engineer � /,,'?., , ---- .' ORit L1 i s 0 14, t, ---;) /I L'''''*-'- Al kit 0.• $fawn M. Dimke, P.E., G.E. i Principal Engineer EXPIRES: 12/31/17 1 cc: Chris Walther, Polygon Homes (via email only) Mike White, City of Tigard (via email only) RSK:SMD:rc One copy submitted(via email only) Document ID:Polygon-123-03-090816-geol-lot_87-89.docx ©2016 GeoDesign, Inc. All rights reserved. G EODESIGN= 3 Polygon-123-03:090816 • r- GEODESIGNN FIELD REPORT Page 1 of 1 GDI Project: Polygon-123-03 Prepared By: Daniel Stai Project Name: West River Terrace Date: 9/8/16 Location: Roy Rogers and SW Jean Louise Rd Report#: 116 Arrival: 1400 Departure: 1530 Weather: Sunny, 70's Permit#: TBA Site Visit Requested By: Mike (Polygon) Met With (on site): , Mike via Phone, Strauss Reps Purpose: Evaluate Subgrade for Lots 53-72 Outstanding Issues: I FR 16& 17(10/21 & 10/22)Areas of fill with low density and high moisture contents in lots 1-9 Lots 53-72 Upon arrival, I observed foundation crews installing concrete forms for lots 56-59 and 61-64. Lots 53, 54, 60, and 65=72, had not yet been excavated to finish subgrade elevation yet. Subgrade soils generally consisted of brown silt; with to minor gravel. I used a Y2 inch diameter steel "T" probe to evaluate subgrade relative consistency for lots 53- 72. Lots 53, 54, and 60 had soil stockpiled over the majority of the lot area. I probed around the edges of the stockpiles. Lot subgrades were generally observed to be very stiff to hard. Lots 65-72 had 6 to 12 inches of loose soil on west side of lot(see attached site plan). I also observed loose utility trench backfill in some of the lots under proposed garage footings. The probe penetrated between 12 to 36 inches into the loose backfill. Strauss representative also informed me that they had over excavated up to 12 inches of loose fill in lots 55-59. Concrete forms will be extended down to account for over excavation. Based on observations, the subgrades for lots 53-72 evaluated today(excluding loose utility trenches) have been prepared in general accordance with our geotechnical recommendations. Distribution: Attachments: Site Plan (1) • Reviewed by: SMD This report presents opinions formed as a result of our observation of activities relating to geotechnical engineering or environmental services W,.rely on t ontract o comply with the plarrscand specifications throughout the duration of the project Irrespective of the presence of our representative Our work does not include supervision dr dire ' of the co clot,the carte of s employees or agents Our firm is not responsible for site safety. This field report is a DRAFT representation of our field observations,testing,an. .efimv� cornnenda Therepo .r only be considered final upon review of the GeoDesign project manager,as indicated by Initials in the"Reviewed By"section. Signature: • • 15575 SW Sequoia Parkway,Suite 100 I. Portland,OR 97224 I Off 503.968.8787 I Fpx 503.968.3068 POLYGON AT WEST RIVER TERRACE" LOT 72 HUB AND TACK CERTIFICATION NE & SE 1/4, SEC. 6, T 2 S, R 1 W, W.M. e?/�s1� 1 ,- ..„,..,..,..--,1-7 CITY OF TIGARD, WASHINGTON COUNTY, OREGON SURVEYED SEPTEMBER 1, 2016 i PREPARED FOR: / POLYGON NORTHWEST COMPANY 109 E. 13TH ST. VANCOUVER, WA. 98660 TRACT A0III . 18" N89'20'24"E 8O,OO j/ s � 1 ; a Z. 25.00 --.*-45 - itI LOT 2 72 o37°' d PI I 0 z 1 F4 CO25.E+' I L N89*20'24"E 80»C C' 1 'N. RUE LCAT IP. ii PUE 0 29' I 71 0 t, 10' ..,...L) 0 (3 REGISTERED I PROFESSIONAL .. LAND SURVEYOR OREGONa. LT o i JULY 9, 2002 TRAVIS C.JANSEN I I0 z 57751 I I 0 RENEWS: 6/30/2017 I I I, TRAVIS C. JANSEN, A REGISTERED PROFESSIONAL LAND SCALE ,2 SURVEYOR IN THE STATE OF OREGON, HEREBY CERTIFY THAT 20 0 10 20 0 I HAVE ACCURATELY SURVEYED AND STAKED THE OFFSETS an — momma TO THE FOUNDATION ENVELOPE FOR LOT 72 OF THE PLAT 1 INCH = 20 FEET GI OF "POLYGON AT WEST RIVER TERRACE" , rRAWN BY: T2 DATP: 9/8/16 f, PACIFIC COMMUNITY DESIGN .aa„ REVIEWED BY: ICJ DATE: 9/8/16 z , –029 PLANNING - ENGINEERING -SURVEYING PROJECT�`- (5t 3) 941-3484