Report octo2 COO. 3. 2007t_10:01AM GECCompass Advisors LLC 5032416566 5032827671 No.3123 P. 5
RECEN5D
LE: VIELLE CEOTECHNICAL P.12. 2007 ; 2313 NEAlevnecla
en Y t r il7A Porilanrl, Oregon 97212
(503) 287 -0511. Fax 282 -7671
BUILDING DIVISION
October 2, 2007 Our ref; 07- 2178 „001
Matt Sievers CITY OF TIGARD
1125 Northwest Couch, Suite $40 Approved 5:i 4.1ic ete> ter` W "" I . t ic
Portland, Oregon 97209 Jnditionally Approved I ]
° ar only the work as described
07 in:
P OMIT No. _ — ()00 3.-- -_
RE: ROCKERY DESIGN • REVIEW Stye Letter to: Follow ( 1 •
1021 I SW 871i' Attach r I 1
Job A�laresv AVA.
TIGARD, OREGON ; ' 1`�s Date: /6-14-r.7
Matt: NarE: wai) A?p& it, - �a 3s. Goa a, a r.N
S Tirs.A ./2.. + 4A ss Mi ”- - AV Rey t *
p%AsNrAw.. c ce. MAY g Q. mMo✓n L
o F - nit W✓a J r •
The 3 -1/2 to 6 foot high, rockeiy wall was constructed to facea out slope at 10211
Southwest 87, in Tigard, Oregon. Our post construction design calculations for this existing
rockery are presented below.
The soils on the site were examined in the cut face exposed between the boulders. Soils
consist medium stiff Clayey Silt.
The attached calculations for rockery wall stability indicate the existing rockery has a factor
of safety greater than 1.,5 for overturning and sliding
The materials used in constructing the rockery and the rockery configuration were
evaluated. We found the wall to have been constructed 'appropriately and in substantial
accordance with following items,
• The rockeiy is built to support a out cut slope in the native medium stiff Clayey Silt.
• The rockery consists of a dry stacked rock wall. that is at lust 2 -3/4 feet thick. The
majority of the boulders used to build the rockery are a minimum of 2 foot in diameter.
Smaller diameter boulders may be used to fill gaps and promote the fit of the larger
stones. The first row of boulders are embedded at least l/4 foot in to the soil at the base
of the wall.
•
• The rockery wall is backfilled with a free draining crushed rock A 3 inch diameter
perforated plastic pipe is laid at the base of the fill behind the first row of boulders. The
drain is expected to have a maximum rate of more than 1 gallon per minute and
therefore we recommend it be directed to discharge on the site.
•
OFFICE, C('Y
oot 03 600.. 3. 2007L10:01AM OECComPass Advisors LLC 5032416566 . 5032827671 No.3123 P. 6
•
October 2. 2007 2 07- 2178.001
• The rockery wall is designed for horizontal backslope, The height of the backstope
should never be increased above 6 feet.
• The rookery boulders .are fresh black basalt. The boulders a sharp ring when they
are struck with a hammer. .•
• The rockery is constructed with a face inclination of.1H:41,
• Rockeries are not structural retaining walls and therefore they should not be relied on in
the same manner as retaining walls. Rockeries are erosion protection for slopes that axe
stable. Rockeries require periodic maintenance to repair frost and potential creep
movements. Rockeries must be protected from surface water run off.
Based on the understanding described above it is our opinioTt that the existing rockery has
sufficient stability.
Sincerely, • -'
,r� i� -
LaVIELLE GEO CHNIC:AL P.C. r •;: `' 4 7�. # ut+ r ,
( - 4e. (2- , _4,4, ,
..... ..\:, .
. . ., ,A,,4, ,; .„,,, . 4 : •
Craig C. LaVielle, ['E /GE
•
a t 02 Oct. c 3. 2007L10:01AM GECComPass Advisors LLC 5032416566 5032827671 No.3123 P. 4
■
• .
■ 10210 SW F'7ih, "Nard Or.
•
10211 SW li7th Tigard, Or. �- - r
Wall Ht. Above Grade 8 feet (H) Unit Wei hR t Basalt Bou d pct- 115 �cf
Surcharge: _ 0 Boulders Size = Minlmum2ft diem �-___
Phl Angle:' 30 deQiaea - _ _, — --- "• ._..�..
Sail Cohesion: D de ._..
Soli Unit Wei hg 110 pcf (wt)
Embedment De h 0 feet (Ed , T •' - - ""
Batter of Wall Face: 4H 1V 14 - _„
degrees + ..
Back Mo. • e: • crlxont8l _ �._ _�___ , w -. -_
Rockery Wall Width 2.76 _
wa —_.. ... , —., _ ...— •
- - - - - -• Ka for a 14 deg i
degree slope face 0.28
NAVFAC DM -7.2 pg.58 _ ; _
Resultant: _ P� _= Ka11YtgH+Ed ^2/ . 554.40 lbs.
Moment Arm: feet Ar = 1/3 H = - ~ _
2.00 ft
Orivin. Forces: „., PeAr 1,101140 ft-lbs ..-
ResIsti Fo rced: iR1 = wt(H +Ed)wldth(F1/4) 2,848.25 ft -lbs. -
_ Factor of Sa fety Aga Inst Over Tumin' = RF%PaAr = .. 2.87 OK -
ii, • —, - h / .- - MI ..i • . — ;
Soil - Passive Case: • ' �_, Kp I tan"2(45+phl/2),= . .. 2.50
- Pp , (wtEd"22ffp)= 0.00 lbs. _ ____ ..,_.-
oil Friction Coefficient; Fc .c tan (friction angle } . " __, 0.45 - -- -- _ .
Friction: _ j > ±Ed)wi(w1dthL _ �
IBase
853 88
- Total Slldng Resistance at Base of Wall: Pp +Fti= ` 853.88 Ibs. _
Factor of Safety Against Sliding: P FRi�/Reauttant - = _� _ 1.54 OK '
Boulder to Boulder Soil Frfctlon Coefficient •Fc a ta (friction__angle , 7 -"
Base Friction: I I Hwt(wfdth)Fc a _ 677.50 _ •
Resultant w/ Surcharge Acting on let Boulder. 311.85 _
. Factor of Safety Against Slldin■: FO/kesultant r 1 :85 OK
•
- ._ _.. .
•
1
4.-
!
MAX. SLOPE
- t 15' t
EXIST. CREEK ,, v _ I
0 0 o '
; V 0 U 0V ° t 4
NON- WOVEN o ° •
GEOTEXTILE FABRIC n .0 0 •
H = 4' MAX.
c c . • D MIN. ROCK SIZE = D/2
STABLE EXCAVATION SLOPE IN DENSE SOIL ° ° 1. MN. WEIGHT OF ANY
(CONTRACTORS RESPONSIBILITY) ) 7C > d• ROCK IN WALL = 250M
c c
(3 ,-u n l�
QUARRY SPACES: PLACED, AS NECESSARY, SUCH
THAT OPENINGS BETWEEN ROCKS ARE FILLED. o ° •
d Q o o 11 11 /�
COMPACT IN I2 LIFTS WITH 0 O
MIN. OF 4 PASSES BY HAND- o ° OG ° 0 o . 0� C \/// � . 4
OPERATED TAMPER. COMPACT • O' O t ) • c 0 I
TO AT LEAST 92% OF MODIFIED
PROCTOR MAX. DRY DENSITY
(ASTM D- I557). BACKFILL
COULD BE PLACED d
COMPACTED AS ROCKS ARE
PLACED. POND BOTTOM
BACKFILL: CLEAN, WELL- GRADED, SAND AND GRAVEL
OR CRUSHED ROCK, 2" MAX. SIZE, 40 -60% GRAVEL,
LESS THAN 5% FINES (PASSING U.S. STD. NO. 200 SIEVE).
FINES SHALL BE NON - PLASTIC.
ALL LOOSE SOIL AT ROCKERY FOUNDATION SHOULD BE
OVEREXCAVATED AND REPLACED WITH COMPACTED
BACKFILL AS DESCRIBED ABOVE. THE EXCAVATION
SHALL BE KEPT FREE OF WATER. THE PREPARED
ROCKERY FOUNDATION SHOULD BE EVALUATED BY A
SOILS ENGINEER PRIOR TO PLACEMENT OF ROCK
RETAINING WALL DETAIL
SCALE : NTS
CITY OF TIGARA - SITE PLAN REVIEW '
BUILDING PERMIT NO.: ( - 1 --- .3 0 07 --000 3 ct
PLANNING DIVISION: j
Required Setbacks: Approved ❑ Not Approved
Side: S reef Side: CITY OF TIGARD -SITE PLAN REVIEW
Front. Gara e:
Visual Clearance: A g roved Rear: BUILDING PERMITNO: — 7 � 7
PP ❑ Not Approved
Maximum Building eight feet ❑ Approved ❑ Not Approved
CWS Service vider Le equired: ❑ Yes ,81 No
Street Trees: A PPro" ed ❑ Not Approved
Protected Trees: •
R ceiv B
l By : Date: pt f 0 7 Notes: Date
E
8
NGINEERING DEPARTMENT:
Actual Slope:..,_ % B Approved ❑ Not Approved
Site Plan: / 0- Approved ❑ Di pproved 13' • By: L.... � Date: /b / �- b 131 Notes:
7 r 0 , ..._
11111 , imp
..ig -,:. 108.06 .
lo 20 3"' 1
11 0 0 LOT 4
8
pp
= � - S. •
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lc ). III
I
85.78' 4
8.01' P4.1 .
8 5/ LOT 5 c (..) INE le i
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