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Plans 0/28/2003 16:38 5032286222 BLAKE AND DUCKLER PAGE 0,3 u;l( FtU(,b03 224 73 24 DUNN CAR2X U1003/012 f 04f2BJ26a3 89:42 5935988705 GEDPACIFIC ENG Pty 02 • F ILE , eoP , OM innineering.Inc. • Roof -World Geotechnlcal Solutions April 27, 2003 Investigation 1 . Design • Construction s Project No. 03 -8207 R Hunt / Z (�d Z Renaissance Homes, inc ©C� I 1672 Willamette Falls Drive '/ West Linn, OR 97068 / 0 1 S Ki v ` �' J l�� FaX (503) 656 -1601 ., SUBJECT: ROCK WALL EVALUATIONS LOTS 4, 6, AND 9 ERICKSON HEIGHTS TIGARD, OREGON Reference: GeoPaclfio Engineering Inc_, Initial Rock Wall Evaluations, Lots 2 -4, 6, and 8-10, Erickson Heights, Project No, 03- •8207, dated April 9, 2003, This letter presents our assessment, findings, end conclusions for the upper rock walls on the above- referenced lots. The main purpose of this•work phase was to provide further evaluation including shallow subsurface explorations by hand, global stability analysis, and more complete evaluation of rookery Wall adequacy. FIELD WORK - Our field geologist performed shallow hand excav €lions and /or probing to further determine the fill adequacy and extent of nonengineered fill. The upper three to five feet in the upper portions of the slope were generally poorly compacted (nonengineered) till. The cross sections were modified to show the depth of poorly compacted fill and are presented on Figures 3 through 5. ANALYSES We performed a global slope stability analysis for circular failure on the tiered wails end slope on what is considered the most critical geometry of the three relevant lots, the tiered slope on Lot 6. Lot 6 has three tiers that have significantly more vertical change than the other two lots. We assumed shear parameters and unit weights based on our experience in similar soil types (Clayey SILT with some weathered basalt rook). The parameters assumed are as follows: Unit Saturated Angle of Equivalent Fluid Active Soli Type weight Unit Cohesion Internal Earth Pressure (Pcf) Weight (pet) Friction • 2H: 'IV Upslope Native soils 13q - (pcf) (degrees) _ (p 4 Compacted Fill 125 130 100 Poorly 125 130— 33 3 0 5 50 _ Compaeted Fill 100 26 So -, 7312 sW Durham Road Portland, Oregon S7224 Tel (503) 698 - Fax (603) 598 -8705 8705 04/28/2003 16:38 5032286222 BLAKE AND DUCKLER PAGE Q4 ,HMV 8 20u 3 1C1:11, :3 CAA 5u3 4V1 (JL4 llUlVN t�AkZIWt X 1 004/0,12 04/28/2003 09:42 5035988705 rEOPACIFIC EH PAGE 03 GEOPACIFIC ENGINEERING, INC. Project No, 83.8207 Erickson Heights Rock Walls VVe also analyzed the factor -of aafeiy against overturning and sliding for the uppermost wall that is supporting poorly compacted fill for the above - listed active earth pressure. The results of our attached analyses were rather consistently around a Factor -of- Safety of 1.4. CONCLUSIONS Based on our site observations, explorations, assumptions, analyses, and findings, we conclude that the existing geometry and rock wall construction on Lots 4, 6, end 9, although less than a Factor Safety of 1.6, Is sufficient such that they da not represent a hazard to the existing residences or adjoining properties. The potential for failure with Factors of Safety of 1.4 is considered low. Natural storm events are considered incapable of saturating the entire slope and significantly reducing the global factor -of- safety to near 1.0. The homeowners should be aware that severely uncontrolled and cencentrated runoff, leaking water pipes, or other sources of potential localized slope saturation may reduce portions the upper wall factor -of- safety to near 1.0 and could cause partial failure of the uppermost rockery wall. We have Included our list of items to consider for maintenance of hillside homesltss to aid the homeowners in safeguarding against such occurrences. Within the limitations of scope, schedule and budget, GeoPaoific attempted to execute our services in accordance with generally accepted professional principles and practices in the fields of •geotechnical engineering and engineering geology at the time the report was prepared, Sincerely, GEOPAcrFIC ENGINEERING, 1Nc. , � F,N c�EO PRQ fib c >S EIN E4;,? ss, ' 1 43 .4p 0 OREGON S ?3, 1� N. e 6 -0Z A. ltd . James D. imbrie, P4E., C.E.Q. Principal Geotechnical Engineer Attachments: Figures 3 through S -- Revised Cross sections Global Slope Stability Analysis Upper Wall Stability Analysis Maintenance of Hillside Homesltes Page 2 •04/28/2003 16:38 5032286222 BLAKE AND DUCKLER PAGE Fly - 04/28/2009 18:11 FAX 503 224 t324 DUNN CARNEY 005/0.12 04/28/2E192 09 :42 5035988705 (aEOPACIFIC ENG PAGE 04 598 84 731Z SW Durham Road CeoPaciffo Portland, 1 - 97224 CROSS SECTIONS C AND D Engleccriiiminr. Tel: (503) 698 -84 5 OevaVon (kW Aho.e Na) 31 0 Pool 3 7 _ 305 — N —305 alb 300— Existing Qrgel® —300 285—. Natural Grade —295 Proposed Inlshed Grade 290-- dated p IIM8n gle plan pprowty Line -290 285 Lot 3 285 Ievetion (Fest Abgvd MAW 310— A Hou tA .-310 309-8 —305 Existing Competent Boll Elevation �? (Frain Hand Probing) ExlatIN Grade 300 Proposed FInlshad Grade Harris-McMona Ie plan —300 .ated Apr111999) 295— Natural Oracle ' • —zs6 ENO 29'0— 1 —290 Lot 4 - 285 0 10 SCALE 1"--10' Horizontal = Verrtioell Date: 03/20/03 Drawn by EJL Project: Erickson Heights Tigard, Oregon Job No: 03 -8207 FIGURE 3 '04/28/2003 16:38 5032286222 BLAKE AND DUCKLER PAGE 06 '04728/2 16 :11 FAX 503 224 7324_ ,., DUNN CARNEY 0006/012 i 84/28/2003 09:42 5035988705 (aEOPACIFIC ENG PAGE 05 7312 SW Ourt)am Road e ®P Iffy Portland, Oregon 97224 CROSS SECTIONS E AND F Enoinncrim rnc. Tel: (503) 598-8445 Elevation , tFec Mime MSIJ 310 x.310 305- `' -305 Existing competent 7,... Soil Elevation Existing Grade 300 (From Hand Probing) ~300 Props Finished Grade (Hauls- McMonaQte pion dr' 205 deChdApril log) ?.....41p - 295 Naturaal Grade OP 290 - -290 • Property t,irpa 235 285 Loth Elovatlon [RNA Above mal,J 305 F 305 PYl eltn® (;rude House r / r 300 '. -300 Proposed Finished Grade AD 29- (Harris -Mcapla plan OP dated Ap ril 19a9) - 29. Natural Gracie ♦ • -290 28 ��IV IMP .11.1111■ -285 Property Lin8 280 - . Lot 3 - —280 0 10 SCALE 1 " =10' Horizontal = Vertical Data; 03/27/03 Drarrn by; I .JL, Project :Erickson Heights Tigard, Oregon Job No: 03 -8207 FIGURE d •04!28/2003 16:38 5032286222 BLAKE AND DUCKLER PAGE 97 • : - . . ..-. _ _.: - ..von 1-Annnx rili 00.7 /012 04/28/2003 09:42 5035988795 GEOPACIFIC EN G PAGE 06 'r —.ten 7 312 SW Durham Road G ®QP (' ' i Portland, Oregon 97224 TAI: (603) 588844$ CROSS SECTIONS G AND H Engineeriva.i Elevation (Peoe Aheua M2L 300— G Proposed Finished Grade - (Harrla- MCMonegle plan G' dated Apra isieg) — 500 Exist! . grade • 295— Existing Competent • Soil Elevation .� fa , —295 (From Hand Probing) -- ?� 290– `- � Natural Grade 401111141' `290 285— r is •s —285 280— a Property hone — 280 275-y Lot 0 —_. 276 Elevation (hetAbava May 300 H M' 300 29 Proposed Finished Grade 295 (Harris- MoMOnagle Alen Usti g Gredo dat,,d April 198e) House [.. 290 gob 290 Nature! Grade OA 285 • • 410.-- -.• 285 280 d�►� 0 - a. •arty Lino 280 I 275 Lot 10 275 0 10 • SCALE 1' =t 0' Horizontal = Vertical D6te: 03/27/03 Project: Erickson Helghte Drawn by: F l� Tigard, Oregon Jbb No: 03 -8207 . FIGURE 6 '04/ _16: 58286 BLAKE AND DUCKLER PAGE 08 - _ . 32 _7 1 - L��.�. fix 0008/812 i 84/28/2803 09:42 5035988705 GEOPACIFIC ENG PAGE 07 • O [0 0 v co L Q, in W ,.. o I! Q u W u_ cn Q U) .,_{ 0 O 0 H -4-J m X (I) o Q -ri t . X Q 1 W 4 - . X LO I— a I— i Q co cr J "'il I:1 � 1� \ ��� f i; N OIE 0 2E 00E O8Z 0 9 a OP Z 4) SIXV — A `04/29/2003 10:50 5032286222 BLAKE AND DUCKLER PAGE 02 UWZ6/,Z 13 :Z AA 4 Tom, MON C;AMihy _. 4008/012 UU3 E1 r 503 ZZ 04/28/2803 09;42 5035988705 GEOPACIFTC E)�Q PAGE • B 8 • • ** pcSTABLam * * - I i by Purdue University , - -Slope Stability , AnalYeia -- jp` �� Simplified Tanbu, EiMplif± 1 Bishop g=7,1=1 or Spencer's Method of Slices Input Data Filename: ericlt6 , ixp Output &'filename: erick6.out Plots ®d Output Filename: erick6.p1t PROBLEM DESCR_IPTTON Erickson Heights Lot 6 BOUNDARY COORDINATES 7 10 Top soundariee 12 Total Boundaries • • Boundary X - Left Y - Left X ltigklt Y -Might Soil Type No. (ft) (ft) (ft) (ft) Below Bud 1 - 00 286.00 14.00 288.00 a 2 14.00 200.00 15.00 292.00 2 3 15.00 292,00 22.00 293.00 • 2 • 4 22,00 293,00 23.00 297..00 3 S 23.00 297,00 31.00 300.00 3 6 31.00 300,00 32.00 304.00 3 7 32.00 304.00 36.50 305.00 3 8 36.50 305,04 37.50 307.00 3 9 37.50 307.00 47.00 307.00 3 10 47.00 307.00 57.00 507,00 2 11 22.00 293.00 47,00 307.00 2 12 14.02 288,00 57.00 298.00 1 ISOTROPIC SOIL ?AMMETERS 3 Type(s) of 'Soil Soil Total Saturated Cohesion Friction Pore Presaurm Pigz, Typm Unit Wt. Unit Wt. Xntercept Angle Pressure Constant Surface • No. (pcf) (pcf) (psf) (deg) Parar. (psf) No. • 1 130.0 135.0 200.0 40.0 .00 .0 0 2 125.0 130.0 100.0 33.0 .00 _0 0 3 125.0 130.0 100.0 26.0 .00 .0 0 A Critical Failure Surface Searching Method, !!sing A Random Technique For Generating Cil Snrfaoas, Bas Been Specified, 400 Trial Surfaces Rave Seen Generated, 200 5urfaees Initiate Prom Sa Of 2 Pointe Equally Spaced Along The Ground Surface EetWten X C 14.00 ft. and X = 22.00 ft. Each. Surface Terminates Between ,X = 39.00 ft. and X .+ 50,00 ft. Unless 1 rther Limitations Were Imposed, The Minimum Elevation At which A 9u4.face extends Is Y =285.00 ft. 5.00 ft. z,ine Segments Define Each Trial Failure Surface_ Restrictiorill ;4.N/ft amen Imposed upon The Angle Of Tnitiatian_ • �' X 10 x500 �� uu rtty caxr�� BLAKE AND DUCKLER .PAGE .03 • = K010/012 04/28/2083 99 :42 5035988705 GEGIPACIFIC ENG .PAGE 89 The Angle Has Been Reetrictod Settees The Ang1e9 Of - 30.0 And 25.0 deg. ' • Following Are Displayed The Ten Moot critical Of The Trial Failure Surface); Rxamined. They Zr e Ordered - Most Critical First. * * Safety Vectors •Are Calculated By The Modified J'anbu Method * * FBilUre Surface Specified By 6 Coordinate Points Point X -Surf Y-Surf No. (ft) (ft) • • 1 22.00 293.00 2 26.63 291.89 3 30.94 • 297.42 4 34.84 300.55 5 38.25 304.21 B 40.18 307.00 *** 1.386 *+►* Individual data on the 12 slices Water Water 'Tie Tie Earthquake Force Force Farce Force Force surcharge -Slice Width Weight Top Bat Norm Tan I-Ior Ver Load NO. Ft (m) Lbs (kg) Lba (kg) Lbs (kg) Lbs(kg) Lbs (kg) Lba (kg) Lbs (kg) Lbs (kg, 1 .0 .0 .0 .0 _0 .0 .0 .0 .a 2 1.0 224.3 _0 .0 .0 .0 • .0 -D .0 3 3.6 .1604.1 ' _0 .0 .0 .0 .0 .0 .0 4 4.3 1626.0 .0 .0 _0 .0 .0 .0 .0 5 .1 18.2 _0 .o .0 .0 .0 .0 .0 6 1.0 516 -7 .0 .0 ,0 .0 .0' .0 .0 7 1.4 916.0 .0 .0 _0 .0 .0 . 0 .0 8 1.5 828,3 .0 .0 .0 .0 .0 .0 .0 9 1.7 699.8 .0 .0 .0 .0 .0 .0 .0 10 1.0 392.1 .0 .0 .0 .0 .0 .0 .0' 11 .8 300.2. .0 .0 .0 .0 .0 _0 .0 12 1.0 337.4 .0 .0 .0 _0 .0 .0 .0 • • • '04/29/2003 10:50 5032286222 BLAKE AND DUCKLER PAGE 04 _. u4rr tsrzuua Ad; iz rAa sus zz T:tz4 llUNN CARNEY 111011/012 114/213/2003 09 ;42 5035988705 GEOPACIFIC ENG PAGE 10 Aft values per twat of wrell All Values per foot of waft. Weight of Rock 194 pal Heel Bearing = 474.4 paf < loge psf oK Coefficient or trlollpff 0.5 To Hoeft R 168.a pet a 0 psf OK Passive Pressure 165 pet E.F.P. 60 pof Area = 4-3 112 Surolarge 0 ft e = 0.376 ft c Avowsbl0 Bearing 1500 psi B / B F,S, Ovefluming 1.5 F.S. Overturning = 1,43 . s 1,5 F.9. aI jg 1.4 ..- F.5, L_ = 1.39 < 1.5 • Hatter g : 1 H1 4 ft 1i2 1 ft 14- W21 6 1 I-1 2.9 ft 6 d1 1 ft • Y 1.67 ft 1 d„„ 1.25 ft . R '=A d2 0.03 ft A r :i.�ai t9sitn: *,rifle ' 9,4 rtg revs r11 A 'a y e i'T> a a i .7+r"i . • All values per foot of well • � o1a " �bvurtuming Moment 1250.0 tuft _ .. : i Sliding Force 750.0 pounds Y ep ; , • t . : e Verticai Weight 1423,7 pounds lb M �dm.e� a ° Resb(Ing Mpmmnt 1753.4 Ibdt o+ a:ti c_r; '.r Raelotfng %salve 990.0 pounds ��,, Resisting Sliding 711.9 pounda 1 7. 7 --- Thud 81din0 Resistanm 1041.0 pounds An Celgtlation are per f of well Overturning Moment = 50pcf - (7ft. + 1it)A2 + ((60pcf • O.9ft. • (Ilk. + 1fk.) - (7f1. / 2).46066.7 ID. - f}, 3 ticlin9 FOrC9 m 5opof • (7ft. + tft.} ^ ^2 /2 + 50pcf - 0_5ft. • (7ft. + iff_ Vertical Weight =184 pct' (5 it • (7it + 1117 - (7tt' 1 tt) " (ten ,24) • (? ft + 1 R) }= 4716.7 pounds Reelsfing Moment in 4718.7 lb ' Z.5 ft. 4 11917.3 lb -ft. Resisting Sliding . 0.8' 4718.7 to 4 2968.3 pounds Passive Resistance = 35Dpcf • (ift. + i1t.)'212 n 700.0 pounds Total Sliding Resistance = 700.0 lb ' 2954.3 TO F 9058,9 pounds 0 = ( 11917.3 lb-ft - 5066.7 lb- It) lb EC 1,0 R Area = 5ttfi2 h =7 -0rt "2 Hoc] Pretcure= 4716. 71b / 7.0ft ' (4•(5R +2 /((3 *( 5 it , + 2.lit.) - e'1.511 1536.7 Toe Pressure = 4716.7 lb /7.01e2 • ( - (6 1.452 ft.. ! ( 5 + 2 '1 ft. ))) = -1554 pet p -s• Overtumlrlg n 11917.3 Ib'ft. /11060.7 lb-ft, a 2.35 F.S. Sliding = 3050.3 lb / 1800.0 lb c LID Batter Angle - *Man (1/4) PI a 14.04 degrees • 04/29/2003 10: 50 5032286222 BLAKE AND DUCKLER •PAGE . V.' /C0 /4VUd AO�1L„„1'A0 aUJ LL4 ' 8 b 2 i/UNN (:AKN�Y t 1012 /012 t7a /taiAae� 1,1:42 5085988705 GEDpACIFIC ENG PAGE 11. GooPecific Engineering, inc. 7312 SW Durham Reed Portland, Oregon 97224 • Tel (503) sa43 MAINTENANCE of HILLSIDE IiOMESITe8 All homes require a certain level of maintenance for general Upkeep and to preserve the overall integrity of structures and land. Hillside hornssItea require Some additionai maintenance because they are subject to natural slope processes, such as euhoff, erosion, shallow soil sloughing, soil creep, perched groundwater, etc, If not properly controlled. these processes could adversely affect your or neighboring properties, Although surface processes are usually only capable of causing minor damage, if left unattended, they oouid pvesbly lead to more serious Instability problems. The primary source of problems on hillsides is Uncontrolled surface water runoff and blocked groundwater seepage which can erode, saturate end weaken soil. Therefore, It is important that drainage and erosion control features be implemented on the property, end that these features be maintained In operative Condition changed on the basis of qualified 'professional advice ). By employing simple precautions, you men help properly maintain your hillside site and avoid most potential problems. The following is an abbreviated list of common Do's and Don'ts recommended fvr maintaining hillside homesites. - AQ t.ist 1_ Make sure that roof rein drains are connected to the street, local storm drain system, or transported vie enclosed conduits or lined ditches to suitable discharge points away from structures and improvements. In no case, should rain drain water he discharged onto slopes or in an uncontrolled manner. Energy dissipation devices should be employed at discharge points to help prevent erosion. 2. Check your roof diming, aUttsr6 and spouts to make sure that they are clear. Roofs are cepnbie of producing a substantial flow of water. Blocked gutters, etc., can cause water to pond or run off in such a way that erosion or adverse oversaturafion of soil can occur. a, Make sure that drainage ditches and /or berms are kept dear throughout the rainy season. If you notice that a neighbor's ditches are blocked such that water is directed onto your property or in art uncontrolled manner, politely inform them of this condition, 4, Locate and check all drain inlets, outlets and Weep holes from foundation footings, retaining walls, driveways, etc. on a regular basis. Clean out any of these that have become clogged with debris. 5. Watch for wet spots on the property. These may be caused by nature' seepage or indicate a broken or leaking water or sewer line_ in either event, professional advice regarding the problem should be obtained followed by corrective action, if necessary, 6. Do maintain the ground surface adjacent to lined ditches so that surface water is collected in the ditch. Water should not be allowed to collect behind or Flow under the lining. Pont List 1. Do not change the grading or drainage ditches on the property without professional advice. You could adversely slier the drainage pattern across the site and cause erosion or soil moverhent 2. Do not allow water to pond on the property. Such water will seep into the ground causing unwanted saturation of soil. 3. Do not allow water to flow onto slopes in an uncontrolled manner, once erosion or oversaturetion occurs, damage can result quickly or without warning. • 4. Do not let water pond against foundations, retaining walls or basements. Such Walls are typically designed for fully - drainaed conditions. 5_ Do not connect roof drainage to subsurface disposal systems unless approved by a geotechnlcal engineer. G. Do not Irrigate to no unreasonable or excessive mariner. Regularly check irrigation systems for leeks- Drip systems are preferred on hillsides,