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Plans Mr. Arnie Fuchs September 3,2020 Foundation Inspection Page 12 14996 SW Summerview Dr Tigard, OR GEOLOGICAL SETTING AND SOILS A geotechnical site investigation was performed at this site by True North Geotechnical.According to the Limited Geotechnical Assessment for True North Project # 20-0224, the surficial soils at the site,which consist mostly of fine-grained alluvium, are underlain by Miocene-age basalt of the Columbia River Basalt group. A hand auger excavation was performed located near the deck posts to a depth of 9.5 feet below the existing ground surface (bgs). A second hand auger excavation was performed located at the foot of the retaining wall to a depth of about 7.0 feet bgs. The subsurface soils consisted of about 3 feet of medium stiff, brown and orange silty clay with sand and gravel, underlain by about 4 feet of soft, gray clay with some sand, further underlain by stiff, brown clay with trace sand until the termination depth of 9.5 feet bgs. Similar conditions were observed near the retaining wall footing before the exploration terminated at 7.0 feet bgs due to trees overhead obstructing the removal of the sampler. It is the opinion of True North Geotechnical that the observed and measured settlement at several of the deck foundations and within the rear-yard wall of the residence is likely due to the presence of soft clay layers, resulting in soil settlement and consolidation over time. It is the opinion of True North Geotechnical, the observed settlement can be mitigated by way of foundation underpinning elements and soil anchors, such as driven push piles, helical piers, and helical anchors embedded into the stiff clay with trace sand that underlies the softer layer at the site. OBSERVATIONS Vegetation around the residence consists primarily of grassy areas with some small to large shrubs. The residence does appear to have a sprinkler system on all sides of the residence. The surface grades on all sides of the residence appear adequate to drain water away from the foundation. No areas of pending water were observed on any side of the residence. Some evidence of foundation movement was observed during the inspection which is noted on the attached Foundation and Elevation Assessment Plan (SK-1). The evidence consisted primarily of grade beam cracks, doors out of plumb, and sloping floors. Relative floor elevations were provided by Ram Jack West. The floor elevations were reportedly taken on August 4, 2020 with a Ziplevel. The Ziplevel is a pressurized hydrostatic altimeter and works by measuring the difference in elevations between the base unit and the handheld unit. The basepoint was reportedly set to 0.0 inch and located near the northeast corner of the second- floor wooden deck. Negative elevations referenced are below the basepoint, and positive elevations are higher than the basepoint. The lowest point was recorded near the northeast corner of the wooden deck. The high point was recorded near the basepoint. The elevation differential between the low and high points of the residence was found to be about 6 inches_ These elevations are shown on the attached Foundation and Elevation Assessment Plan (SK-1). RECOMMENDATIONS I recommend a total of four(4) helical steel piles be installed at the 2nd floor wooden deck. Deck pile locations are shown on the Foundation and Elevation Assessment Plan (SK-1). Additionally, BOX 10393/Eugene,OR, /541,393.7363/WWW.NWENGGROUP.COM Mr. Arnie Fuchs September 3,2020 Foundation Inspection Page 13 14996 SW Summerview Dr Tigard, OR I recommend a total of nine (9) helical piles and six (6)tiebacks be installed at the retaining wall. Retaining wall pile locations are shown on the Foundation and Elevation Assessment Plan (SK- 2). The steel piling system used should have an evaluation service report (ESR) recognized by ICC-ES showing compliance with the currently adopted International Building Code (IBC). The helical steel piling system should have a minimum allowable working load of 10 kips and be capable of uniformly raising the foundation as applicable. The minimum installation torque for the helical piles is 2,300 ft-lbs. The helical tieback system should also have a minimum allowable working load of 10 kips The purpose of underpinning the foundation is to support portions of the structure that has experienced some differential settlement. The underpinning piles are designed to support the structural loads in the immediate areas where they are placed and not to prevent uplift from soil heave. Maintaining uniform moisture around the foundation is very important. The landscape grades around the residence should be maintained to slope away from the residence where required. The landscape grades should slope away from the foundation at a minimum of%" per foot for six (6'-0)feet. The top soil should extend a minimum of one (1'-0)foot above the bottom of the grade beam and should not extend above four(4") inches below the bottom of the siding. All new fill soil should be clayey sand with a minimum Plasticity Index(PI) of twenty-five (25). Watering the soil around the foundation is also important during dry periods to help maintain uniform moisture in the soil. This concludes this report. Observations made in this report pertain to the condition of the residence on the date of the inspection which is subject to change. No foundation warranty is expressed or implied by this report. If I can be of further assistance ,•. . ; • u have any questions about this report, please do not hesitate to contact me. R°4 GINS FS, o 4 Ir8 4 Z 7..G✓/lv ' 4,/Sincerely, ry GON 0 -we ow. EXPIRES: Sean Morrison E.I.T. Charles Steffensmeier P.E. Engineering Technician Civil Engineer Attachment: Site Plan(SK-0) Foundation and Elevation Assessment Plan at Wooden Deck(SK-1) Foundation and Elevation Assessment Plan at Retaining Wall (SK-2) Ram Jack Helical Pile Detail with 4038 Bracket at Wooden Deck(SK-3) Ram Jack Helical Pile Detail with 4038 Bracket at Retaining Wall (SK-4) Ram Jack Helical Tieback Detail at Retaining Wall (SK-5) Footing & Pile Calculations Ram Jack 4038 Bracket Shop Drawing Ram Jack 2 7/8" Helical Pile Specification P.O.BOX 10393/Eugene,OR,97440/ 541.393.7363/WWW.NWENGGROUP.COM 14996 SW SUMMERVIEW DR ` o PROPERTY x '1)� ENTRY S ---____ �Qa WOODEN DECK 1, 10'-4" \ RETAINING + N WALL \ N. � N ``\ 207' #/` ~_ _ �, SITE PLAN ( 20 gtoReo PRoFFS Aiii TREE PRESERVATION NOTES: v" . try. s1) ,/ �R y , 1.ALL HOLES ARE EXCAVATED NEXT TO THE STRUCTURE FOUNDATION NORTHH 2.THE TOTAL AREA OF EXCAVATED HOLES<25 SOFT ice ,v ; S4°F STEF0' NORTHWEST ARNIE&SHIRLY FUCHS SHEET: EXPIRES: .01 14996 SW SUMMERVIEW DR ENGINEERING GROUP TIGARD,OR SK-0 P.O. BOX 10393 SCALE: DATE: EUGENE,OR 97440 (541)393-7363 1/30"=1'-0 09/03/2020 _, FOR FINAL INSPECTION.... PROVIDE DRIVE LOG...AND ENGINEERS FINAL SUMMARY LETTER. INSPECTOR WILL WANT TO SEE PILING ATTACHMENT TO FOUNDATION BEFORE BACKFILL. SPECIAL INSPE 11uN trice,cUlRED State of Oregon S. ctural Specialty Code ❑ Concrete and Relnfo i g Steel _ ❑ Bolts installed in Co rate 14996 SW SUMMERVIEW DR D Special Moment-Restating Concrete Frame ❑ Reinforcing Steel & estressing Steel Tendons Mg O Str►actural Welding MOM i ❑ Hip-Strength E'� it}•_'- (4" 0" 0" 0" 0" 0" I ❑ Structural Masonry I WOODEN ❑ Reinforced Gypsum oncrete y2' -1 Y4" I DECK �° 4Ya' SYa" 0g®mac. ❑ Insulating Concrete 'ill I 1 i 1 )1 -5" -4 " ! CD CD ❑ Spray Applied Ftre-R sistive Materials -6" 03 \ �l Pilings, Drilled Piers and Caii3 OOR 6'-0 02 '�—_� i,. 6'-0" j, CANTILEVER X ❑ Shotcrete LIMITS ❑ Special Grading, Excavation and Filling ❑ Smoke-Control Systems ❑ Other Inspections WOODEN DECK FOUNDATION & ELEVATION '� p ASSESSMENT PLAN NORTH Ran PROF S `� LEGEND oGiN so R 2 88 r ,� 1/ — -Y" ---- FLOOR ELEVATIONS TAKEN BY RAM JACK ON 08/04/2020 I • E�" a- 0 ----HELICAL STEEL PILE (10 KIP CAPACITY) DOE rrefs % ., EXPIRES. N n R T'H W E S"' ` ARNIE FUCHS SHEET: •/�// v 14996 SW SUMMERVIEW DR S K-1 ENGINEERING GROUP TIGARD,OR P.O. BOX 10393 SCALE: DATE: EUGENE,OR 97440 (541)393-7363 3/32"=1'-0 09/03/2020A RETAINING WALL cr. 05 Y2'CONCRETE SEPAATION FOUNDATION ®06 Ti JUMP RETAINED SOIL " CONCRETE 07 SEPARATION 08 4T2 T3 R T4 T5 T6 1 Y2'CONCRETE ®9 SEPARATION O" ®10 11 •=p" ® 13 , �4'-0°j12 10'-0° 1:6° 1 Y2"CONCRETE SEPARATION Ali RETAINING WALL FOUNDATION & ELEVATION 1111, ASSESSMENT PLAN NORTH ��R¢D PRopte LEGEND NGI "49 soy ® ----HELICAL STEEL PILE(10 KIP CAPACITY) ---HELICAL TIEBACK(10 KIP CAPACITY) n!SON k mom. - --C6X8.2 x 4'-O"CHANNEL '4e JOE STHfC'el4b NORTHWEST ARNIE FUCHS SHEET: /'/ 14996 SW SUMMERVIEW DR SK-2 EXPIRES: f R/•?1i TIGARD, OR ENGINEERING GROUP P.O. BOX 10393 SCALE: DATE: EUGENE, OR 97440 i541)393-7363 3/32"= 1-0 09/03/2020 -, • - -w r_ _ / 1 SIMPSON COLUMN CAP EXISTING 6x12 TIMBER BEAM EXISTING 6x6 SIMPSON 6x6 APPROXIMATE EXTERIOR TIMBER COLUMN GRADE ELEVATION,SOIL POST BASE OR BRICK PAVING. (VERIFY EXACT 1"0 ALL ± a a CONDITIONS IN FIELD) THREAD I U 0- N -' _ i 2 z ke r 6 f DOUBLE NUT AND WASHER \ --)c--y .i 6#4 VERTICAL AND I RAM JACK NEW 3#3 HORIZONTAL I CONSTRUCTION 12" DIAMETER I BRACKET HOOPS WI PL Vex 8"x 0'-8 AND I 16"0 CONCRETE .� 3 Y2"x 10"SLEEVE BASE(SONOTUBE) l''''-.. HELICAL PILE (REF.TABLE 1) MIN. EMBEDMENT DEPTH = 15 FT —p— TABLE 1 PILE HELIX PILE MIN. BRACKET DIA. CONFIG. SERVICE INSTALL. LOAD TORQUE 4079 2%" 10" 10.0 KIP 2,300 FT-LBS 4_tiRE11 PROS 'J/ �p �NGINe �41 oy TYPICAL HELICAL PILE DETAIL 1a soe STEFF*t' NORTHWEST ARNIE & SHIRLY FUCHS SHEET: EXPIRES: Z Z 14996 SW SUMMERVIEW DR S K—3 ENGINEERING GROUP TIGARD, OR P.O. BOX 10393 SCALE: DATE: EUGENE, OR 97440 1541)393-7363 3/4"= 1'-0 09/03/2020 APPROXIMATE UPHILL ELEVATION, SOIL OR CONCRETE PAVING. (VERIFY EXACT CONDITIONS IN FIELD) / - CONCRETE RETAINING WALL o } v w EXTENT OF EXISTING w EXISTING FOOTING BEYOND p CONCRETE o w STEM WALL \ I CHOCT EXISTING FOOTING IP- UT FLUSHPO POCKET WITH IN FOUNDATION f WALLAS NEEDED TO INSTALL BRACKET. - _No , I APPROXIMATE DOWNHILL ELEVATION, SOIL OR CONCRETE PAVING. (VERIFY EXACT CONDITIONS IN FIELD) TABLE 1 BRACKET MUST SUPPORT THE BOTTOM OF THE FOOTING AND SHALL PILE HELIX PILE MIN. NOT RELY ON POST-INSTALLED BRACKET DIA. CONFIG. SERVICE INSTALL. ANCHORS FOR GRAVITY SUPPORT. LOAD TORQUE 4038 2%8" 10" 10 KIP 2,300 FT-LBS HELICAL PILE(REF.TABLE 1) MIN. EMBEDMENT DEPTH = 15 FT 0,013 PR01 '►" 11 �a� aGIN', s, I! i)i 4 0#488904 : _42 �� TYPICAL HELICAL PILE DETAIL ilIF:p R. a `mac- � @ RETAINING WALL FOUNDATION F3o 20' # �OE BTEFf- NORTHWEST ARNIE&SHIRLY FUCHS SHEET: E%PIRES: i 1a/ZZ 14996 SW SUMMERVIEW DR SK-4 .70 ENGINEERING GROUP TIGARD,OR P.O. BOX 10393 SCALE: DATE: EUGENE, OR 97440 1541 j 393-7363 3/4"=1'-0 09/03/2020 ' 1 X"0 x 18"ASTM-A36 ALL-THREAD w/WEDGE --\\ 2 " 0 x 0.19"WALL, (Fy=65 WASHER KSI, Fu =80 KSI)WITH (2)3q"0 SAE J429 GRADE 8 THRU BOLTS v -- o N _4O n ig 02 TYPICAL 2 3/8" 0 TIEBACK CONNECTION DETAIL APPROXIMATE UPHILL ELEVATION, SOIL OR CONCRETE PAVING. (VERIFY EXACT CONDITIONS IN FIELD) EXISTING CONCRETE WALL ____ T 8 Y2"0 HOLE THROUGH WALL (GROUTED) TABLE 1 C8x11.5 x 2'-6" PL yz"x 7"x 0'-7 PILE HELIX PILE MIN. (ASTM-A36) DIA. CONFIG. SERVICE INSTALL. LOAD TORQUE e' N 2'/" 10" 10 KIP 2,300 FT-LBS 4 a HELICAL TIEBACK N (REF.TABLE 1) N 411111 C 0 l APPROXIMATE EXTERIOR GRADE ELEVATION, SOIL MIN. EMBEDMENT DEPTH =20 FT OR CONCRETE PAVING. .0/ O (VERIFY EXACT �, p. D PROF CONDITIONS IN FIELD) `0` 6N61M�''' '1, TYPICAL 2 7/8" 0 HELICAL /) IA 01 TIEBACK ANCHOR DETAIL (� v I 'ON �4- b !. 20 4. Os odb Oe STEFO' NORTHWEST ARNIE&SHIRLY FUCHS SHEET: 14996 SW SUMMERVIEW DR 5 K-5 acq+ s: •,zZ ENGINEERING GROUP TIGARD,OR P.O.BOX 10393 SCALE: DATE: EUGENE, OR 97440 (541)393-7363 314"= 1'-0 09/03/2020 NORTHWEST PILE CALCULATION Date: 9/03/2020 • ENGINEERING GROUP Designer: Charles Steffensmeier, P.E. P.O. Box 10393 Project: Arnie &Shirley Fuchs Eugene,OR 97440 14996 SW Summerview Drive Tigard, OR 4,0.0 PRO% Design Loads: vim`' ,G*NE o Roof Live Load = 25 psf a' f .904 4, r' Roof Dead Load = 15 psf /i Tributary Length = 5 ft wesig 5�as Tributary Width = 4 ft ,7y� �41 Floor Live Load = 40 psf ��OE sTEF4�a Floor Dead Load = 15 psf EXPIRES: / Tributary Length = 5 ft Tributary Width = 4 ft Deck Live Load = 40 pcf Deack Dead Load = 15 pcf Tributary Length = 6 ft Tributary Width = 3 ft Total Weight on Pile = 289• Pile Working Loads: Pile Service Load, PTL= lbs Pile Ultimate Load,P,1T= lbs *Safety Factor of 2 Applied Minimum pile Installation torque 4,rnm - h: Required ultimate soil capacity(Quit)= lbs Pile 0= 2 7/8" Torque factor(Kt)= 9 Minimum pile installation torque, Min)_ /00 ft-lbs Bracket= 4038 Bracket Allowable Capacity= 19,700 lbs Page 1 �^ 'l '~�, � 3K�a�0 PRpFFS //9f6. s� cJl�nJ/�71r'v`C� 1 Jc. vc` , r31N F S'o R s f r ,,�'/' ; coral k ' f e � !'gTEfEt //'r /ram/ 4 Xcf t7A1i �� 0, 4/5. tyo• VZ• t3 = �o 72 /ems gy „' � ,i✓i.+r>v 4,27 Vic., '4o.✓7;57vc w ZZ a5c P 7_%- occ,z Ce-"ci - lac% /G,e Z 35 �'r✓�� / .moo G�3 ' — V Rev Revision note Date Slgnat Checl NOTES: UNLESS OTHERWISE SPECIFIED No ure ed i i 1'-3 1/2" ill 3 1/2" O.D. SLEEVE f \I i(FY=MIN. 65 KSI) r4 �9-.eill 14 mince a�•sm— \ = I11All .`af EyII;i ill] , _________HIIlimill FASTENING STRAP WITH 11 11 Ca 'Co I AND DIA. NUTSL THREADS II 11 ! I 1 ii ii i 1 11 + u u I I 1 1 2 7/8" DIA. HELICAL PILE \ -• ___T__- 4107.7B �3 1/2" 3• 3 1/2" A FRONT (VIEW liii UI / 10 / 3 1/2" ' DIA BRACKET SLEEVE MU TOP VIEW 3/8" BRACKET SEAT r NOTES. I 1 1. POLYETHYLENE COPOLYMER THERMOPLASTIC COATING PER ICC—ES AC 'd 1 228 M r I 3. MANUFACTURER TO HAVE IN EFFECT INDUSTRY RECOGNIZED WRITTEN Io ,� � QUALTY CONTROL FOR ALL MATERIALS AND MANUFACTURING 11 _� PROCESSES. quij TYP. INSTALLATION 4. ALL WELDING IS TO BE DONE BY WELDERS CERTIFIED UNDER SECTION 5 SCALE: 1"=1' OF THE AWS CODE 01.1. '4111115. THE CAPACITY OF THE UNDERPINNING STSIEM IS A FUNCTION OF MANY INDIVIDUAL ELEMENTS, INCLUDING THE CAPACITY OF THE FOUNDATION, BRACKET, PIER SHAFT, HEUCAL PLATE. AND BEARING STRATA, AS WELL 'o AS THE STRENGTH OF THE FOUNDATION BRACKET CONNECTION AND THIS or1AYAND AND ns CONTENTS ARE THE QUALITY OF THE INSTALLATION OF THE PILE. YOUR ACHIEVABLE CONFIDENTIAL AND THE EXCLUSNE PROPERTY CAPACITY COULD BE HIGHER OR LOWER THAN THOSE USTED DEPENDING N ; , 1 OF RAM JACK SYSTEMS DISTRIBIION, LLC. ON THE ABOVE FACTORS. NO PUBLICATION, DISTRIBUTION OR COPIES MAY BE MADE WITHOUT THE EXPRESSED 6. RAM JACK ENGINEERING HANDBOOK FOR ALLOWABLE VALUES AND/OR SIDE VIEW WRITTEN CONSENT OF RAM JACK SraILMS CONDITIONS OF USE CONCERNING MATERIAL PRESENTED IN THIS DOCUMENT. DISTRIBUTION, U.C. ALL RIGHTS RESERVED UNDER COPYRIGHT LAWS. UNLESS OTHERWISE SPECWED� • DIMENSIONS ARE IN INCHES • TOLERANCES: ANGLE *1' ""4038 PILE BKT, ?SDI la AFST s[AL[ 3 PLACE DECIMALS t .010 sll� A-SIZE TITLE BLOCK 2 OF 7 1 V2""1' A2 PLACE DECIMALS ± .02 JACK° • REMOVE ALL BURRS AND SHARP EDGES DRAWN 10-2-08 CHARLES T.MARVIN t 1 • PARENTHETICAL INFO FOR REF ONLY f . HOLE TOLERANCES C»a DARIN WILLIS .013 + 125 + .251 + APPIL DARIN WILLIS ..151 .250 -ao, .500 a0, ,SSML 4035 HELICAL PILE BRACKET .501 +Au! .751 +am 1.001+a1Z my EWOI» _ ,.. .7 m, 1.000 °°, Hu m, e»MLI» 40 3 8-0 2-0 7 1 2 . 875"0 HELICAL PILES AND ANCHORS — UPSET CONNECTION ,� _ �I _—�----- IFINC gum =__ 0 a7 O a I , o 0 0 0 o o Jli „A„ A" I "A" I LEAD SECTION HELIX EXTENSION EXTENSION MECHANICAL TORQUE RATING - 6,000 FT-LB LEAD SECTION TABLE HELIX EXTENSIONS ULTIMATE CAPACITY(TENS/COMP) - 54.0 KIP" ALLOWABLE CAPACITY(TENS/COMP)-27.0 KIP" CAT.# "A" "B" "C" "D" CAT# "A" "BASED ON A TORQUE FACTOR(Kt) = 9 6125 5'-0 8" 8605-8 5'-0 8" 6140 5'-0 8" 10" 8605-10 5'-0 10" 6142 5'-0 10" 12" 8605-12 5'-0 12" 3Yz" 6143 7'-0 10" 12" 8607-10 7'-0 10" it t 6147 7'-0 8" 10" 12" 6148 , r-o 10" 12" 14" EXTENSIONS = 6188 I 10'-0 10" 12" 14" CAT# 4) N O 7/8"0 HOLES TO *MULTI-HELIX ARE SPACED 3 DIAMETERS 8605 5'-0 ACCEPT 3/4"0 OF THE LOWEST HELIX. 8607 T-0 THRU BOLTS 8610 10'-0 NOTES: _ 2'/8"O.DPILING 1. POLYETHYLENE POLYMER THERMOPLASTIC COATING PER ICC-ES AC 228.(GALVANIZED AND UNCOATED PILES AVAILABLE UPON REQUEST) CONNECTION 2. LEAD AND EXTENSION SECTION LENGTHS ARE NOMINAL. DETAI L 3. SHAFT MATERIAL IS 27/8" O.D., 0.217"WALL, MINIMUM Fy=65 KSI AND Fu=80 KSI,ASTM -A500. 4. HELIX BLADE MATERIAL IS HOT ROLLED, MINIMUM Fy=50 KSI AND Fu80 KSI CARBON STEEL.PLATE THICKNESS IS AVAILABLE IN 3/8"AND Yi'THICKNESSES. 5. NOMINAL SPACING BETWEEN HELICAL PLATES IS THREE TIMES THE DIAMETER OF THE LOWEST , HELIX. 6. MANUFACTURER TO HAVE IN EFFECT INDUSTRY RECOGNIZED WRITTEN QUALITY CONTROL AND �� ASSURANCE FOR ALL MATERIALS AND MANUFACTURING PROCESSES. 7. MANUFACTURER SHALL BE ISO CERTIFIED. 8. ALL WELDING IS TO BE DONE BY WELDERS CERTIFIED UNDER SECTION 5 OF THE AWS CODE mct.w.tms.0.2 o,,uooNo.:smTnem Rom., 9. ALL COUPLING BOLTS TO BE 3/4"ID,SAE J429 GRADE 8 BOLTS.(SAE J429 GRADE 5 IF GALVANIZED). SCALE DRAWNSv DATE: 07111,„ $„E�,�, 9li'"VC SR l REED SEP 1 10EIV 2n?0 September 2, 2020 CITY OF TIGARD BUILDING DIVISIO!,,aelgi Ram Jack West TRUE NORTH PO Box 11701 Eugene, OR 97440 Attn: Ms. Carley Weise Subject: Limited Geotechnical Assessment 14996 SW Summerview Dr. Tigard, Oregon 97224 True North Project#20-0224 Dear Ms. Weise: At your request, True North Geotechnical Services (True North) is providing you with this report summarizing our limited geotechnical assessment for the proposed installation of drilled helical pile underpinning at the above-mentioned address. PROJECT UNDERSTANDING We understand that settlement of up to 51/4 inches has been observed in the southern parts of the home. The most extreme settlement occurs under the posts supporting the second-level deck and nook area. Cracking and lateral shifting has also been observed in the concrete wall retaining the slope south of the home, We understand that four (4) helical piles have been proposed to lift and stabilize the affected deck posts, as well as nine (9) helical piles and six (6) helical tie-backs to stabilize the retaining wall. Ram Jack will attempt to recover as much of the home's settlement as possible, and will stabilize the foundation in place. SITE CONDITIONS Regional Geology According to DOGAMI-published geologic mapping of the site area (Madin, 2004),the surficial soils at the site, which consist mostly of fine-grained alluvium, are underlain by Miocene-age basalt of the Columbia River Basalt group. The location of the existing residence with respect to existing site features and local geology is shown on the Vicinity Map— Figure 1. Surface Conditions A site reconnaissance was performed by True North on August 25, 2020. The subject property is in the Bull Mountain neighborhood of Tigard, Oregon,which is defined by the hilly, sloping topography of Bull Mountain. The home itself is two stories, roughly rectangular, with a south-facing daylight basement and second-level deck. South of the home, the slope is retained by an approximately 67 linear-foot concrete retaining wall ranging from 1 to 4 feet tall. The ground surface surrounding the home slopes to the southeast, with elevations ranging from approximately 430 feet above mean sea level (AMSL) in the northwest to 420 ft AMSL in the southeast and down to about 390 feet AMSL below the retaining wall at the base of the property. 202 E Evergreen Blvd Suite B,Vancouver,WA 98660 - 360-558-0005 www.tnorthgeo.com True North Geotechnical Services The proposed foundation repair plan and the location of our explorations with respect to the existing home are shown on Figures 2 — Repair Plan and Figure 3 —Site Plan, respectively Subsurface Conditions The purpose of our explorations was to evaluate subsurface conditions and provide geotechnical recommendations for design and construction of the proposed foundation repair. Subsurface conditions at the project site were evaluated by advancing two (2) hand auger explorations near the deck posts, and one (1)exploration at the foot of the retaining wall (see Figure 2— Repair Plan and Figure 3 — Site Plan). The hand auger excavations located near the deck posts, designated HA-1 and HA-2, advanced to depths of 9.5 feet below the existing ground surface (bgs). The hand auger excavation located at the foot of the retaining wall, designated HA-3, advanced to a depth of about 7.0 feet bgs. An interpreted hand auger boring log is included at the end of this report. Directly below the ground surface at HA-1 and HA-2, the subsurface soils consisted of about 3 feet of medium stiff, brown and orange silty clay with sand and gravel, underlain by about 4 feet of soft, gray clay with some sand, further underlain by stiff, brown clay with trace sand until the termination depth of 9.5 feet bgs. Similar conditions were observed in HA-3, before the exploration terminated at 7.0 feet bgs due to trees overhead obstructing the removal of the sampler. Based on the site topography and the layout of the home and wall, it is our opinion that the observed upper soft clay may constitute fill placed during the original grading of the subdivision. These observations appear consistent with our site reconnaissance, as well as the soils observed in nearby well logs for adjacent properties. Static groundwater was not observed in our excavation. CONCLUSIONS AND RECOMMENDATIONS Based on the results of our literature review and surface and subsurface evaluations, the existing deck and wall foundations are both underlain by a 3.5 to 4.5-foot thick layer of soft clay with sand in the upper 10 feet of the soil profile. It is our opinion that the observed and measured settlement at several of the deck foundations and within the rear-yard wall of the home is likely due to the presence of this soft clay layer, resulting in soil settlement and consolidation over time. In our opinion, the observed settlement can be mitigated by way of foundation underpinning elements and soil anchors, such as driven push piles, helical piers, and helical anchors embedded into the stiff clay with trace sand that underlies the softer layer at the site. Underpinning Pile Design Recommendations Driven and/or helical piles may be used to carry the deck foundation loads. Driven piles will derive their capacities primarily from skin friction and end bearing resistance in the native stiff clay encountered below approximately 7.5 feet bgs at the deck and below approximately 5 feet bgs at the wall foundations, and helical piles will derive capacities from plate bearing resistance in the same soils. We understand that Ram Jack Drilled Helical Pile or Driven Pier foundation elements are being proposed,which will be installed in accordance with the manufacturer's recommendations and criteria as outlined in the ICC-ES Report 1854. Ram Jack West—14996 SW Summerview Dr. September 2,2020 Project#20-0224-1 Page 2 of 5 True North Geotechnical Services We anticipate the underlying native stiff clay with trace sand can be expected to support an allowable (assuming a factor of safety of 2.0)vertical compressive load of at least 15 kips per driven pile or drilled helical pile installed. The installation force used to advance a driven push pile can be directly correlated to the ultimate capacity of the pile, and will be observed and recorded during installation. Torque required to advance a helical pile can be correlated to soil shear strength and helical pile capacity, and will be observed and recorded during installation. Based on commonly accepted empirical correlations, we estimate the allowable load can be achieved with helical piles with an installation torque resistance of approximately 3,000 foot-pounds. In general, we recommend that piles of either type be installed to a depth of at least fifteen (15) feet in order to ensure end bearing in medium stiff native soils to achieve the above-mentioned compressive load, although the actual final depth of the piles will be determined during the installation process. Spacing and/or the location of the driven piles or drilled helical piles should be determined by the structural engineer. Lateral Resistance: Lateral loads can be resisted by passive earth pressure on the existing building foundation elements. A passive earth pressure of 200 pcf per foot of embedment may be used, assuming a factor of safety of 1.5 due to the amount of movement required to mobilize resistance. Due to anticipated disturbance as a result of the pile installation that may reduce the effective footing surface upon which the passive resistance may be relied upon, additional lateral passive resistance may also be achieved by way of encasing the newly installed foundation elements in new concrete (i.e. grade beams) and using the same recommended passive earth pressure. For footings and walls in contact with the native fine-grained soils,we recommend using a coefficient of friction equal to 0.35 when calculating resistance to sliding. Pavements or the upper 12-inch depth of adjacent unpaved areas should not be considered when calculating passive and/or frictional resistance. These values do not include a factor of safety. Helical Anchor Design Recommendations Drilled helical tieback anchors may be used to carry the wall loads. Helical tieback anchors will derive their capacities primarily from plate bearing resistance in the underlying native clayey silt. We understand that Ram Jack Drilled Helical Tieback elements are being proposed, which will be installed in accordance with the manufacturer's recommendations and criteria as outlined in the ICC-ES Report 1854. Lateral Loads:The two possible conditions regarding the ability of the wall to yield include the active and at-rest earth pressure cases. The active earth pressure case is applicable to a wall that is capable of yielding slightly away from the backfill by either sliding or rotating about its base. The at- rest earth pressure case is applicable to a wall that is considered to be relatively rigid and laterally supported at the top and bottom and therefore is unable to yield. The structural engineer must decide whether the repaired retaining wall will be allowed to yield or held rigid with the new anchors. Based on our observations during our site visit, we are assuming that the backfill area is roughly horizontal and will be completely drained. For that case, yielding walls can be analyzed using an Ram Jack West—14996 SW Summerview Dr. September 2,2020 Project#20-0224-1 Page 3 of 5 True North Geotechnical Services active earth pressure on the basis of a hydrostatic pressure distribution and an equivalent fluid unit weight of 40 psf per foot of depth. Correspondingly, non-yielding walls can be analyzed using an at-rest earth pressure on the basis of a hydrostatic pressure distribution and an equivalent fluid unit weight of 60 pcf. To account for seismic loading, the earth pressures should be increased by at least 40%. The resultant of the additional seismic force can be assumed to act at a distance of 0.6H measured up from the base of the wall, where H equals the overall height of the wall. Helical Anchor Capacity: Lateral resistance may be obtained by means of helical tieback anchors at the base of the wall. In general, helical tieback anchors drilled at an inclination of about 15 to 20 degrees from horizontal and extending to lengths of at least 10 feet or more. Helical anchors will derive their capacities primarily from plate bearing resistance in the medium stiff to stiff silty clay expected to be located behind the wall. We anticipate the underlying native medium stiff silty clay can be expected to support an allowable (assuming a factor of safety of 2.0)tensile load of at least 10 kips per drilled helical anchor installed. Torque required to advance a helical anchor can be empirically correlated to soil shear strength and helical anchors capacity. We understand the installation data will be observed and recorded during installation. For helical anchors, based on the criteria presented in ICC-ES Report 1854, an allowable load of 10 kips can be achieved with an installation torque resistance of approximately 2,000 psi. In general, we recommend that the anchors be installed to an embedment length of at least twenty (20) feet at an angle of approximately 15 degrees below horizontal in order to ensure end bearing in stiff native clay soils and achieve the above-mentioned tensile load, although the actual final length of the anchors will be determined during the pile installation process. Spacing and/or the location of the anchors should be determined by the structural engineer. Load Testing Proof tests are generally performed on a specified number of the total number of production piles to confirm the contractors design and provide information regarding the ability of the production piles to withstand the design loads without experiencing excessive movement or creep. As mentioned, the pressure required to advance driven piles can be directly correlated to the pile capacity, and will be observed and recorded during installation. In our opinion, if the driven pile installation capacities and depths are in line or exceed those recommend in this report, pile load testing shall not be required. If any of the piles do not meet our recommended capacities and depths, we recommend proof tests be performed on the specific piles to a minimum of 150 percent of the design load. A successful proof test will sustain the test load for at least one time-log cycle up to 10 minutes with less than 0.04 inches of movement. If such a test is not successful, the load is held up to an hour. The maximum deflection at the design load must also be less than the maximum allowable deflection as designated by the structural engineer. Proof load testing criteria should be included in the project specifications. Ram Jack West—14996 SW Summerview Dr. September 2,2020 Project#20-0224-1 Page 4 of 5 True North Geotechnical Services LIMITATIONS • We have prepared this report for use by the owner and other members of the design and construction team for the underpinning of the existing residence at the above-mentioned address. The opinions and recommendations contained within this report are not intended to be, nor should they be, construed as a warranty of surface or subsurface conditions, but are forwarded to assist in the planning and design process. We have made observations based on our explorations that indicate the soil conditions at only those specific locations and only to the depths penetrated. These observations do not necessarily reflect soil types, strata thickness, or water level variations that may exist in other locations. If subsurface conditions vary from those encountered in our site exploration, True North should be alerted to the change in conditions so that we may provide additional geotechnical recommendations, if necessary. The future performance and integrity of the underpinning work will depend largely on proper initial site preparation, drainage, and construction procedures. Observation by experienced geotechnical personnel should be considered an integral part of the construction process. The conclusions and recommendations contained in this report are based on our understanding of the currently proposed underpinning work, as derived from written and verbal information supplied to us by you. When the design has been finalized, we recommend that we review the design and specifications to see that our recommendations have been interpreted and implemented as intended. If design changes are made, we request that we be retained to review our conclusions and recommendations and to provide a written modification or verification. Within the limitations of scope, schedule, and budget, our services have been executed in accordance with the generally accepted practices in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. CLOSING We appreciate the opportunity to be of service to you. If you have any questions, or if we can be of further assistance to you, please contact us at (360) 558-0005. Respectfully Submitted, ,��O PROPS_ 414GINEE9 'c 85828PE 9! ____ 20 OREGON "- 4 LE'NBER 6 y � �OTNY J. NO Exp. 12/31/20 Timothy J. North, P.E. Principal Engineer Attachment: Figure 1 —Site Geology and Vicinity Map. Figure 2—Repair Plan Figure 3—Site Plan Key to Boring Symbols and Terminology Hand Auger Logs HA-1. HA-2 and HA-3 Ram Jack West—14996 SW Summerview Dr. September 2,2020 Project#20-0224-1 Page 5 of 5 TRUE NORTH TABLE Al •GEO0ECHNlCAI _ Key to Test Pit and Boring Terminology and vtiow 2D2 E Evergreen Blvd Suite B,Vancouver,WA 360-558-0005-tlm@tnorthgeo.com MAJOR DIVISIONS SYMBOLS TYPICAL DESCRIPTION GRAPH LETTER p oo o 00 G W Well-graded Gravels,Gravel-Sand Mixtures, Clean Gravels t 0 00 0 c Little or No Fines Gravel and Gravelly Soils (Little or No Fines) GP Poorly-graded Gravels,Gravel-Sand Mixtures, rn m Little or No Fines rO N 0 More Than 50%Coarse en N N Fraction Retained on No.4 GM Silty Gravels,Gravel-Sand-Silt Mixtures -o 2 p Sieve Gravels with Fines > 0 , Z (Significant Percentage of Fines) •C GC Clayey Gravels,Gravel-Sand-Clay Mixtures L Lo O a>o . l;..... Ur m cs fn SW Well-graded Sands,Gravelly Sands, Clean Sands Little or No Fines (1.) i- m Sand and Sandy Soils (Little or No Fines) . Poody-graded Sands,Gravelly Sands, ce 0 0 Ce More Than 50%Coarse S p Little or No Fines Fraction Passing No.4 SM Silty Sands,Sand-Silt Mixtures Sieve Sands with Fines (Significant Percentage of Fines) SC Clayey Sands,Sand-Clay Mixtures ML Inorganic Silts and Very Fine Sands,Rock aFlour,Silty-Clayey Fine Sands,Clayey Silts y o Z Liquid Limit Less / A C+L Inorganic Clays of Low to Medium Plasticity, •p C Silts and Clays than 50 percent Gravelly Clays,Sandy Clays,Silty Clays cn S' o , I N OL Organic Silts and Organic Silty Clays of Low 2 coco .2 - Plasticity 1— d O Inorganic Silts Micaceous or Diatomaceous (r y ( O MH Fine Sand or Silty Soils N d� N• o Liquid Limit Greater Silts and Clays than 50 percent CH Inorganic Clays of High Plasticity,Fat Clays EL- i OH Organic Clays of Medium to High Plasticity. ii/,,ii,' Organic Silts ( . l' • ♦ ♦ ♦ • + • * + * • pT Peat,Humus,Swamp Soils ♦ ♦ ♦ ♦ • ♦ ♦ * * + Topsoil '�j�jt Humus and Duff Layer Fill Highly Variable Constituents Relative Density of Coarse-Grained Soils 7C7C Consistency of Fine-Grained Soils Relative Density N -Blows per Foot Relative Density N -Blows per Foot Very Loose 0-4 Very Soft 0 -2 Loose 4- 10 Soft 2 -4 Medium Dense 10-30 Medium Stiff 4-8 Dense 30-50 Stiff 8- 15 Very Dense 50+ Very Stiff 15-30 Hard 30-50 Key to Sampler Type Symbols Very Hard 50+ G X II Grab SPT Shelby Dames & Rock Tube Moore Core Project Name Ram Jack West-14996 SW Summerview Dr HAND AUGER LOG HA-1 Project Location Project No. TRUE NORTH 14996 SW Summerview Dr,Tigard,OR 97224 20-0224-1 •GEOiECNNICAE• • Equipment Operator Date Started WOW" 3"AMS Auger SMP 08/25/2020 Logged By Checked By Date Completed 202E Evergreen Blvd Suite B,Vancouver,WA SMP TJN 08/25/2020 360-558-0005-tim@tnorthgeo.corn 0 O C T •O O E o 6 a.) H Z N N U (/) U _c n a m E 0 Soil 3 Notes and Lab a)o cn <o op Description iJ: Data 6"silty,sandy topsoil with gravel and organics • Medium stiff,brown and orange silty CLAY with sand and gravel;low 1 ♦ plasticity;fine sand;sub-angular gravel;moist.(POSSIBLE FILL) G s-1 • ♦ CL 2— ♦ • • 3— • • ♦ Soft,gray CLAY with some sand;low plasticity;fine sand; moist. 4 G S-2 • (POSSIBLE FILL) • • 5 — • • CL • 6— ♦ • • 7— • • G S-3 Stiff,brown CLAY with trace sand;low plasticity;fine sand; moist. 8 CL 9— 1 O Excavation terminated at 9.5 feet bgs.Groundwater not encountered. Backfilled with excavated soils. 11- 12- 13- 14- 15 • Project Name Ram Jack West-14996 SW Summerview Dr HAND AUGER LOG HA-2 Project Location Project No. TRUE NORTH 14996 SW Summerview Dr,Tigard,OR 97224 20-0224-1 • Equipment Operator Date Started 3"AMS Auger SMP 08/25/2020 Logged By SMP Checked By TJN Date Completed 08/25/2020 202 E Evergreen 5• SuRt o Vancouver.WA 360.6358-8-0005•tim@Vwrthgeo.com �! C) >, o o E w, J >, O • m o o cn 0 a) Q E E U Soil - 73 Notes and Lab o cOO c i 0 D Description : LE Data 6"silty,sandy topsoil with gravel and organics ♦ Medium stiff, brown and orange silty CLAY with sand and gravel;low 1 — ♦• plasticity;fine sand;sub-angular gravel;moist.(POSSIBLE FILL) • CL 2— ♦ • • • 3— • • Soft,gray CLAY with some sand;low plasticity;fine sand; moist. 4- • (POSSIBLE FILL) • •• • • CL • 6— ♦ ♦ • 7— ♦ • ►/ Stiff, brown CLAY with trace sand;low plasticity;fine sand; moist. 8— CL 94— Excavation terminated at 9.5 feet bgs.Groundwater not encountered. 10 — Backfilled with excavated soils. 11- 12- 13- 14- 15— Project Name Ram Jack West-14996 SW Summerview Dr HAND AUGER LOG HA-3 1 Project Location Project No. TRUE NORTH 14996 SW Summerview Dr,Tigard,OR 97224 20-0224-1 •c EcrECNNicnL— Equipment Operator Date Started mil► 3"AMS Auger SMP 08/25/2020 Logged By Checked By Date Completed 202 E Evergreen Blvd Suite B,Vancouver,WA SMP TJN 08/25/2020 360-558-0005-tm5lnorthgeo.com 0 0 E C c—, J >, O 0) 0 o cA U a) a E E Fic Soil ' Notes and Lab o U) cn co 0D Description I' Data 6"silty,sandy topsoil with gravel and organics ♦ Medium stiff,brown and orange silty CLAY with sand and gravel;low 1 — • CL plasticity;fine sand;sub-angular gravel; moist.(POSSIBLE FILL) • Soft,gray CLAY with some sand;low plasticity;fine sand; 2— ♦ moist.(POSSIBLE FILL) • 3— • cL • • 4— • • 5 Stiff, brown CLAY with trace sand;low plasticity;fine sand; moist. 6— % CL 7— Excavation terminated at 7.0 feet bgs.Groundwater not encountered. Backfilled with excavated soils. 8- 9- 10 - 11- 12- 13- 14- 15