Plans r ^ 04/,28/2003 16:38 5032286222 BLAKE AND DUCKLER PAGE 03
04 /ztizoo 16:10 FAX _503 224 7324 DUNN CARUEX 121003/012
04/28/ 2083 09: 42 5635988705 6EOPACIFIC ENG Pty 02
FILE cDpy
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hutinepring.lic.
Real -World Geotechnlcal Solutions
April 27, 2003 Investigation ■ Design - Construction Support
Prrjeet No 03 -8207
Steve Hunt 17 DC7 - (9 pC 3 C)
Renaissance Homes, Irlc.
1672 Willamette Falls Drive I 0 ' 1 v 5 K 4 B
West Linn, OR 97068
Fax (503) 656 -1601
SUBJCT: ROCK WALL EVALUATIONS
LOTS 4, 6, AND 9
ERICKSON HEIGHTS
TIGARD, OREGON
Reference: GeoPaclfia Engineering Inc_, initial Rook Wail Evaluations, Lots 2 -4, 6, and 8-10,
Erickson Heights, Project No, 03 -8207, dated April 0, 2003,
This letter presents our assessment, findings, and 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 excavations and/or probing to further determine the fill
adequacy and extent of honenglneered fill. The upper three to five feet in the upper portions of the
Slope were generally poorly compacted (nonengineered) fill. 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 faqure on the tiered walls and 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
Soil Type weight Unit Cohesion Internal Earth Pressure
(Pcf) Weight (psi) Friction 2H: IV upslope
Native Solis 13p (cf (degreers) (pot)
Compacted Fill 125 130 1 pp 40 50
Poorly 126 130 33 50
Compacted Fill 100 26 60
7312 SW Durham Road
Portland, Oregon 072.20 Tel (503) 698 -8443
Fax (603) 598.8709
04/28/2803 16:38 50322_86222 BLAKE AND DUCKLER PAGE 04'
wwTFO /LVUJ to:tu raA
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04/28/2003 09:42 5035988705 r,EOPACIFIC ENG PAGE 03
GEOPAC1FIC ENGINEERING, INC.
Project No, 03.8207
Erickson Heights Rock Wails
We also analyzed the factor of afety against eve+ltuming and sliding for the uppermost wall that la
supporting poorly compacted fill for the above- iieted 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, and 9, although less than a Factor -of-
Safety, of 1.6, Is sufficient such that they do 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 concentrated 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 homesltes to aid the homeowners in safeguarding against such
occurrences.
Within the limitations of scope, schedule and budget, QeoPecitiic attempted to execute our services
in accordance with generally accepted professlort>;il principles and practices in the fields of
geotechnical engineering and engineering geology at the time the report was prepared,
Sincerely,
GEOPACiFiC ENGINEERING, INC.
1 743
/
• OREGON
AIN
c 0, 11
. James D. Imbrie, P,E., C.E.Q.
Principal Geotechnical Engineer
Attachments: Figures 3 through 5 — Revised Cross sections
Global Slope stability Analysis
Upper Wall Stability Analysis
Maintenance of Hillside Homesltes
Page 2
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.,...
7312 SW Durham Road
GeoPacifig Portland, Oregon 97224 CROSS SECTIONS C AND D
EflUhiccririti,rer° Tel: (503) 598 -8445
leVAtion
(Rim. Ahtmel S(
310
faoal - 310
_ 305—
O —305
300- - 410
Existing Grade L-300
285- Natural Grade
-205
Proposed Inlsned Grade
290- (Harrle- McMonagla plan
dated April 194m)
Propert Line -290
285
Lot 3 285
E levation
•
tr'Bet Ahgvd Mal)
310- House r
D'
—310
309-•
411 -305
Existing Competent 8011 Elevation
(Pram Hand Probing) alellr,q Grade
300 PrctPosed PinIshed Grade
(Harris-McMone re plan -300
•aced ApHI.1989
295— Natural Grade
4101fth■— ^95
290— O
x'290
28
Lot 4 285
0 10
SCALE 1"=.10'
Horizontal = Vertioel Date: 03/20/03
Drawn by EJL
L Pject= Erickson Heights
Tigard, Oregon Job No: 03 -8207 FIGURE 3
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7312 SW Durham Road
eaP Lila Portland, Oregon 97224 CROSS SECTIONS E AND F
Egroineerim,,Inc. Tel: (SOS) 698 -8446
Elevation
(Feat ACV v hMSl,)
310 i E' 310
306 -
" -305
6Iatln0 Campetent 7-.
Soil Elevation Existing Grade -
300- (From Hand Probing) ^300
Propoeed Finished Grade
(Hants- McMonegle plan dr.
205, dated Apo isss
-295
Natural Orada or .
290- i,
-290
• Property t,irla
2,65-f -
•
Lot 6 285
Elevation
(Foal Ahoue Mat,)
3115 -- F 305
EYlal s) Grade
House
300 -
�,. 300
NIP
Proposed Ftntshed Grade 4 r
295 (Harris- McManagie plan
dated April 1959) . --285
fi
290- Natural pt&de 410 1110,imi
-290
dill, -41111 OW
28$- d0�■' --285
. Property Line
280-' - ---.........1
Lot •
— 280
0 10
SCALE 1 " =1 0'
Horizontal = Vertical Data: 03/27/03
Driewn by; EJL,
Project: Erickson Heights
Tigard. Oregon Job No 03 -8207 FIGURE 4
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G 7312 SW Durhaim Road
11®oP c�� i Portland, Oregon 97224
rnnineedno.tnc. Tel: (503) 588 -8445 CROSS SECTIONS AND H
Elevation
(Peat Above MgL
no- Proposed Finished Grade
(Hams MCMonegto plan G'
dated April 15129) - 300
Eris ti a Oracle
295- Existing Competent
Sail Elevation 1 • -295
m
(Fro Hand Prnl,lrlg) ---- \ —
290
Natural Grade
IOW* -290
285-. 4.
•
•� -265
280 •
Property Une - 280
275-+ -
Lot 0 276
Elevation .
(P bet Above kttlil)
300
—300
20
Proposed Finished Grade -295
[Harris MoM4nagle Plan CAnt( g Grade
datrd April 1 43 House
290
■
-290
Natural Grade dB"
285 r
•� -'• -.265
280 •
...arty Ling 280
275
Lot 10 z7s
a 10
SCALE 1 "10'
Horizontal = Vertical Date: 03/27/03
Project: Erickson Heights Drawn by: FJL
Tigard, Oregon Job No; 03 -8207
FIGURE 5
061-/..28/20133__16:38 5032286222 BLAKE AND DUCKLER PAGE 08`
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B4/29/2003 10:50 5032286222 BLAKE AND DUCKLER PAGE 02
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04/28/2003 09;42 5635980705 GEOPACZFTC ENO PAGE 68
* * PCSTABLSM **
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RECEI
by
Purdue Driiversity Y {
rr, '� 3
- -Slope s Analymia -.-
Simplified Sanbu, Simplified Bishop i,` -y OF ill l RD
•
or Spencer's Method of Slices U,LE,� �t t�rt�(ON
Input Data Filename: orick6.inP
Output Filename: orick6.out
Plotr ®d Output Filename: erick6.plt
PROBLEM DESCRIPTION Erickson Heiglite Lot 6
•
BOUNDARY COORDINATES
Z TO Boufcdariee
12 Total Boundaries •
Loundary X -Left Y -Left X-- Rigklt Y -Right Soil Type
No. (kW (ft) (ft) (ft) Below Bud
1 - 00 286 1.4.00 288.00 1
2 14.00 22a,00 15.00 292.00 2
3 15.00 292,00 22.00 293,00 • 2
• 4 2 2,00 293,00 23.00 297.00 3
• 5 23.00 297,00 31.00 300.00 3
6 37..00 300.00 32.00 304.00 3
7 32.00 304.00 36.50 305.00 3
8 36.50 305,00 37.50 307.00
9 37.50 307.00 47.00 307.00 3
10 47.00 307.00 57.00 301,00 2
11 22.00 293.00 47,00 307.00 2
12 • 14.00 285,00 57.00 298.00 1
.ISOTROPIC SOIL PAA4 ETERS
3 Type(s) of Soil
Soil Total saturated Cohesion Friation Pore Pressures P_i,ez,
Type (YUC Wt. Unit Wt. Xntercept Angle Pressure Constant Surface
• N4. fpcf) (pcf) fpsf) (deg) Param. (pot) 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, Using A Ran,dom
Technique For Generating Circular Sirfac ®a, Bar Been Specified.
400 Trial Surfaces Rave Been Generated.
200 Surfaces Initiate Prom Ea Of 2 Points Equally Spaced
Along The Ground Surface Betwten X e 14.00 ft.
and X = 22,00 ft.
Each .Surface Terminates 19etween ,X = 39.00 ft.
and X K 50„00 ft.
Unless Further Litnitattprxs Were Imposed, The Minimum Elevation
At whieb A su Extends 15 Y =295,00 ft,
5.00 ft. Line Segments Define Each Trial Failure Surface_
Rescrictionsa NAve $een imposed Upon The Angle of Initiation_
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The Angle Has Been Restricted BetWeen The Anglen Of -30.0
And 25.0 deg. '
Following As Displayed The Ten MooG critiea7. of The Trial
1railure Surfaaep Bxamined. They Are Ordered - most. Critical
First.
* ' Safety Fectors.Are Calculated By The Modified J•anbu Method * *
P8i7.ure Surface Specified By 6 Coordinate Points
Point X -Surf Y-Surf
No. (ft) (ft)
1 22.00 293.00
2 26.63 294.89 '
3 30.94 ' 297.42
4 34.134 300.55
5 38.25 304,21
•
5 40.18 307.00
*** 1.386 *0.*
Individual data on the 12 abeam
Water water Tie Tie Earthquake
For Force Force Force Force Surcharge
,Ui,ce Width Weight Top Sat Norm Tan Hor V'er Load
No. Ft(m) Lbs(kg) Lbe(kg) Lbs(kg) Lbs(kg) Lb9(kg) Lbe(kg) Lba(kg) Lbs
(kg)
.o
1 . . .0 .0 _0 .0 .0 .o
2 1.0 224.3 _0 .0 .0 .0 .0 .D
.0
3 3.6 1604.1 _0 .0 .0 ,0 . 0 _0
•
.0
4 4.3 1626.0 .0 ' _0 _0 .0 .0 .0
•
.0
5 .1 18.2 .0 .o .0 .0 .0 .0
.0
•
6 1.0 516.7 .0 .0 ,0 .0 .0 .0
.0
7 1.4 926.0 .0 .0 _0 .0 .0 .0
_0
8 ],.a 828.3 .0 - .0 .0 .0 .0 .0
.0
9 1.7 694.8 .0 .0 .0 .0 .0 .0
.0
10 1.0 392,1 .0 .0 .0 .0 .0 .0
.0
11 .8 300.1 .0 .0 .0 .0 .0 _0
.o
12 1.9 337.4 .0 .0 .0 _0 .0 .0
.0
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All Values per fort vrwWl All Values oat foot of waft.
Weight of Rock 134 psi Heel Bearing = 474.4 pet .c 1500 pet QK
Coarfialant or elc498 0,5 To Bearing A 158,2 pef a 0 psf OK
Passive Pressure 165 pcf
E.P.P. 66 pot Area = 4.5 ft
Surcharge O ft 0 m 0,376 ft c B/ 6
Ailowablo Beuring 1500 pal
F,$. Overturning 1.5 F.S.Overtumin
F.S. suing 1.5 9 = 1,43 5 1,5
F.5, Sl idlns) = 9. 39 < 1.5
sstror a :1
H1 4 ft
FJ2 1 ft
R1 2.5 ft 1f
d1 _ ux ,' 1
1 ft
Y 1.67 ft 1 + A
den 1.25 ft �-%
d2 o.es ft 4 ..f r o
e>s gnA1e 0, degrees nt ;; a >in
` t.
4 . -
Alt values per foot or wall 1414 _ '
cunning Mom ent 125ito Ittft fi n %:
Sliding Force 750.0 pounds �� ''
Vertical Weight 1433,7 pounds 143 �''LM a1rQ s l a
Ros ating Mpm�nt 179x.4 loft o1 1
1
• Roslatf tg Passive 330.0 pounds I `I
Resisting Sliding 711.9 pounds i1
Thlii Batting Rosict*ryCQ 1 041.0 pounds
All calculations are per foot of wall
Overturning Moment = Sopd * (7ft. + 1ft)K2 / 2 + ((S0pcf • 0,6ft. ' (rft, + 11},) - (7ft. + it) / 2)446066.7 le. - ft,
sliding POro9 n 50por' (7ft. -f 1ft.)""2 + 50pcf' 0-5ft.' (7ft, + ift.
Ver ool Weight =134 par* (5 ft' (7ft + tft) - (71t+ 1 ft) " (1en 4.2) ' (7* + 1 ft))= 4716.7 pouhd6
Reelsting Moment n 4715.7 lb' 2.5 ft, 411917.3 lb
Resisting Sliding 4 0.8.4718.7 lb 235$,3 poutuio
Passive Resistance = 350pcf' aft. + eft -r2 / 2 a 700.0 pounds
Total Sliding Resistance - 700.0 lb 4 280.3 to A aa5e,a pound&
e = (11917.3 !b-ft - 5066.7 Ib -ft)) 4716.7 lb c 1,3 ft
Area= 5ft +2'1 ft 7 - 0ft.2
Heel Pressure 4716.7 lb / 7.0t • (4 t (5 ft + 2 - 1 ft.) / ((3' (5 ft, r 2 1 1t) - 8 ' 1.5 ft. )) = 1535.5 pet
Toe Pressure = 4716. 7lb /7.0ff"2•(1- (8•1.462 ft. /(5 2'1ft))) 15,0 per
P.S. Overturning p 4 19'17,3 1b41./ 5ose•7 lb-ft, c 2.35
F.8. Sliding = 3058.3 lb / 1800,0 lb c 1.70
Satter Angle - arctan (1 / 4) ` 180/ PI a 14.04 degrees
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r.i
GeoPecific Engineering, inc.
7312 SW Durham Road
Portland, Oregon 97224 • Tel (503) 59&8445
MAINTENANCE OF HILL,SIDiE MOMESIT®8
All homes require a certain level of maintenance for general upkeep and to preserve the overall integrity of structures and
land. Hillside horpee1tas require some eddttionel maintenance because they are subject to natural slope processes, such
as runoff, erosion, shallow soli sloughing, soil creep, perched groundwater, eta, If not properly controlled, these
processes could adversely affect your or neighboring properties, Although surface processes are usually only capable of
causing minor dernege, if left unattended, they oould possibly lead to more serious Instability problems.
Tne primary source of problems en hillsides is Uncontrolled surface water runoff and blocked groundwater seepage which
can erode, saturate and 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 (unless changed on the basis of qualified
'professional advice). By employing simple pr80autions, you coin 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 for maintaining hillside
homesites,
PO List
t _ Make sure that roof rein drains are connected to the street, !omit storm drain system, or transported via enclosed
conduits or lined ditches to suitable discharge points away from structures and improvements. in no case, should rain
drain water be discharged onto slopes or in en uncontrolled manner. Energy dissipation devices should be employed
at discharge points to help prevent erosion,
2_ Check your roof drains, goiters and spouts to make sure that they are clear. Roofs are capable of producing a
substantial flow of water. Sleeked gutters, etc., cen cause water to pond or run off in such a way that erosion or
adverse oversaturation of soil can occur.
3, Make sure that drainage ditches and /or berms are kept clear 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 Wells, 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 natural eaepage 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,
e. 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.
Jjon't List
1. Do not change the grading or drainage ditches on the property without rofessional advice.
the drainage pattern across the site and cause erosion or soli moverhe Y ou could adversely alter
2. Do not allow water to pond on the property. Such water will seep into the ground causing unwanted saturation of soli.
3. Do not allow water to flow onto slopes in an uncontrolled manner. once erosion or ovarseturation 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 -
dnained conditions.
5_ Do not connect roof drainage to subsurface disposal systems unless approved by a geotechnlcal engineer.
6, Do not Irrigate in an unreasonable or excessive manner. Regularly check irrigation systems for leaks. Drip systems
are preferred on hillsides,