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Report - • ADaPT Engineering, inc. 17700 SW Upper Boones Ferry Road, Suite 100 Portland, Oregon 97224 Tel (503) 598 -8445 • Fax (503) 598 -8705 January 26, 2000 Q U Job No. OR99 -2429 — 2 Q Properties, Inc. tb. Venture Pro p , y �- 4230 Galewood, Suite 100 Lake Oswego, OR 97035 Attention: Jeff and Christy Weigel GEOTECHNICAL RECOMMENDATIONS FOR ROCKERY RETAINING WALL DESIGN EAGLES VIEW SUBDIVISION TIGARD, OREGON References: 1. Geotechnical Investigation, Columbia Geotechnical, Baggenstos Property, May 20, 1999. 2. Geotechnical Review, ADaPT Engineering, Inc., Geotechnical Review, November 2, 1999. At your request, this letter presents design calculations and specific recommendations and details for rockery retaining walls during construction at the above - referenced site. Please refer to the attached detail for incorporating into the project plans and to the accompanying calculations (Figures 1 and 2). Based on a review of the most recent plans, we understand that rockery walls are proposed along the back of Lots 98 through 106, 50, 51, and along a water quality swale located at the southwest corner of the site. The walls vary in height from one to six feet The only walls to be retaining proposed fill are along Lots 50 and 51, all other walls will be in cut. The fill walls on Lots 50 and 51 and 105 and 106 are the most difficult because they are so close to the property line, they cannot be overfilled and cut back into compact fill. This wall must be built concurrently with the fill. For this reason, select granular material, 4 to 8 inches angular rock should be utilized for at least 12 feet (equipment width) behind the wall. We have attached a hand sketch showing this difference (Figure 3). We have included our recommended detail and design calculations for an up to 7 -foot tall rockery wall. Since most of the walls are between four to six feet in height, the calculations and detail should be more than sufficient for approval. The on -site soils are considered OSHA soil type B. The wall base width should be at least 60 percent of the wall height. A seven -foot tall wall was modeled to cover any deviations in actually constructed wall height. As an alternative note to the design detail (Figure 1), a minimum of 6 inches of 4 " -0 crushed rock can be placed at the wall of the wall in lieu of 1 " -0 to increase the coefficient of friction to 0.5. We trust this information meets your need have any questions, please call. ckEO R OFES F- NGI NfER si0 S ADaPT Engineering, Inc. � ‘k 14743 / 9 • James D. Imbrie, P.E., v �REGO 9 Geotechnical Engineer �4 23, 9 § F, 4 " S D. I0 0- CP' 30 -0 1 Attachments: Figure 1 - Rock Wall Detai Figures 2.1 and 2.2 - Design Calculations Figure 3 — Specific wall sketches Cc: Jay Harris, Harris - McMonagle Associates Page 1 ROCK SIZE SCHEDULE (Eqn. = 250D + 250) LBS. ROCKERY WALL DESIGN D (FT) MIN. WT. (LBS.) TYPICAL SIZE (IN.) MAXIMUM WALL HEIGHT (H) = 9 FEET • 9 2,500 38 X 36 X 20 DRAWING NOT TO SCALE 29 X 29 X 29 36 X 30 X 20 7 2,000 28 X 28 X 28 5 1,500 34X 26X 18 LEVEL TO 2H:1V MAX. SLOPE 25 X 25 X 25 3 1,000 28 X 25 X 16 22X22X22 22 X 19 X 14 COMPACTED SILT 1 500 18 X 18 X 18 OR CLAY SOIL I ' THICK) o , ( to 24 INCHES � _ PROF —F-1- • °g o g° °° (--D NGINEE AS S / ' -IR% 0 5•° aa° ° ° p R o : p° S °p° Sa = -` �; °9.f o� 1474 1 � d C • D . °J °° p aa,°- • Ps (.�` I : c ; 'ecc�3 ° \ STABLE TEMPORARY CUT 4±1 MIN. WT °` ` ' (SLOPE ANGLE VARIES) OR .... EGON i 250D +250 F ° ° ✓ O H 3 o,.C I R'- vi FS D. 1M ° °� _:`ji = °_ 4 "-0 CRUSHED AGGREGATE, u _ ° � LIGHTLY COMPACTED IN 12 EXP. 6 - 30 - 991 0 1 - ,° °o�,.°, INCH LIFTS F 0.35H I - 'aGd ► °O0‘ 1 1/2 "-0 CRUSHED AGGREGATE -_ ao WITH NO MORE THAN 7% FINES PASSING THE No. 200 SIEVE, 12 IN. MIN. 1 ,° ° p ° LIGHTLY TAMPED G+ o, 6 IN. : �, 4 a O d' ¢ �4d • ..- 4 IN. DIAM. MIN. PERFORATED PLASTIC PIPE 1 44 ■ . i SCHEDULE 40 or ADS HIGHWAY GRADE KEYWAY ' 0.4H MIN. FOR OSHA STABLE ROCK, 0.5H MIN. FOR OSHA 'TYPE A" SOILS, AND . CONSTRUCTION NOTES 0.6H MIN. FOR OSHA 'TYPE B" SOILS , 1. For walls supporting engineered fill, the fill should be overbuilt and the wall constructed against an excavation into already compacted fill. 2. Keyway subgrade and embedment depth should be verified by ADAPT ENGINEERING, INC. 3. Rocks should have a cubical, tabular, or semi - rectangular shape that roughly matches the space created by the previous rock course. Rocks should be laid flat with the long dimension oriented perpendiclular to the wall and extending towards the excavation face. Rocks should be staggered such that each rock bears on at least two rocks below and vertical joints are discontinuous. Rock placement and wall integrity should be checked (by builder) by lightly hammering on the top of each rock with excavator bucket. 4. Minimum rock sizes should be determined using the ROCK SIZE SCHEDULE above, where D is the distance from the base of the rock to the top of the wall. Rocks should be no smaller than 500 lbs. 5. Voids greater than 6 inches wide where there is no contact between adjacent rocks should be chinked with a small rock. 6. Backfill behind the rocks should consist of an average 12 -inch -wide sheet of 4 "-0 crushed aggregate with no more than 7% fines passing the U.S. Standard No. 200 sieve. Backfill should be placed in lightly compacted to an unyielding state in 12 inch lifts as each course of rocks is placed. ADaPT Engineering, Inc. 17700 SW Upper Boones Ferry Road FIGURE 1 Portland, Oregon 97224 All values per foot of wall All Values per foot of wall. Weight of Rock 144 pcf I Weight ( #) Distance (ft.) I Resisting Moment (#-ft) ' Coefficient of friction 0.5 W1 1152.0 1.333 1536.0 Passive Pressure 375 pcf W2 1915.2 3.000 5745.6 E.F.P. 55 pd W3 1152.0 4.667 5376.0 ' Surcharge 0 ft. W4 388.8 3.333 1296.0 Horizontal Force 0 pounds W5 388.8 2.667 1036.8 at d3 distance 0 ft. Allowable Bearing 2500 psf SUMS ) 4996.8 - I 14990.4 F.S. Overturning 1.5 F.S. Sliding 1.5 Batter 4 :1 H7 7 f H2 1 ft L1 0.5 ft. w'4, 12 4 ft. L3 0.5 fl ' d1 0.5 ft d2 1.8 ft. H3 1.4 ft . H4 0.5 ft. wo Batter Angle 14.04 degrees All values per foot of wall 1 I Yol Overturning Moment 4693.3 #-ft. Sliding Force 2668.1 pounds Vertical Weight 4996.8 pounds Resisting Moment 14990.4 #-ft. Iv,: W Resisting Passive 1523.0 pounds Resisting Sliding 2498.4 pounds Total Sliding Resistance 4021.4 pounds X i - KM Re ure 9a74ra ' � oveoo vvvaeov� Y fIl r Lirrimia..--vg I ( ( J jer .......„,,,,, II -+ j • :•1� l I ...new sea �o elll s -11 agg F f---i 11111ir x I . ( _ oscasum..o uoyass .sour sws v[ -ll =II- IIT15_.rjli"ra .. *- 0GNEE,Q ss /° ti c / OREGON dg �� .(0 3oc�1 o.� F- 2A All Values per foot of wall. Toe Bearing = 1526.1 psf < 2500 psf OK Heel Bearing = 472.6 psf > 0 psf OK Area = 5.0 ft Section Modulus = 4.2 ft e= 0.439 ft c8 /6 F.S. Overturning = 3.19 > 1.5 OK F.S. Sliding = 1.51 > 1.5 OK All Calculations are per foot of wall Overturning Moment = 55pd • (7ft. + 1 ft.) "2 / 2 Sliding Force = 55pcf • (7ft. + 1ft. + 1.4ft. + 0.5ft.) "2 / 2 W1= (7ft. +1ft.) "2 /(2 1152.0 pounds W2 = ((7ft. + 1ft. - 1.35ft) • (4ft. - ((7ft. + 1ft.) / 4))) • 144pcf = 1915.2 pounds W3 =( 7ft.+ 1ft.) "2'144pcf /(2'4)= 1152.0pounds W4 = 0.5 • 1.35ft • 4ft. • 144 ft. = 388.8 pounds W5 = 0.5 • 1.35ft. • 4ft. • 144 ft. = 388.8 pounds Total Vertical Weight = 1152.0 + 1915.2 + 1152.0 + 388.8 + 388.8 = 4996.8 pounds Distance @W1 = 2 +1ft.)/(3 1.333ft. Distance © W4 = ((4ft. - ((7ft + 1ft.) / 4)) / 2 + ((7ft. + 1ft.) / 4) = 3.000 ft. Distance @ W3 = 4ft +(( 7ft +1ft.) /(3'4))= 4.667ft. Distance @ W4 = ((7ft. + 1) / 4ft.) + (4ft. / 35 = 3.333ft. Distance @ W5 = 4ft. • 2/3 =2.667 ft. Resisting Moment @ W1 = 1152.0# • 1.333ft. = 1536.0# -ft. Resisting Moment @ W2 = 1915.2# • 3.000ft. = 5745.6# -ft. Resisting Moment @ W2 = 1152.0# • 4.667ft. = 5376.0# -ft. Resisting Moment @ W2 = 388.8# • 3.333ft. = 1296.0#-ft. Resisting Moment © W2 = 388.8# • 2.667ft. = 1036.8# -ft. Total Resisting Moment = 1536.0# -ft. + 5745.6# -ft. + 5376.0# -ft. + 1296.0N-ft. + 1036.8# -ft. = 14990.4 #-ft. Resisting Sliding = 0.5 • 4996.8# = 2498.4 pounds Passive Resistance = 375pcf • (1ft. + 1.4ft. + 0.5ft.) "2 / 2 = 1523.0 pounds Total Sliding Resistance = 1523.0# + 2498.4# = 4021.4 pounds e= (0.5 ft. + 4 ft.+ 0. 5ft.) /2 -( 1 4 #- ft.- 4693.34-ft.)/4996.8#= 0.439 Section Modulus = (0.5ft. + 4 ft. + 0.5 ft.) "2 / 6 = 4.2 ft "3 • Area =0.5 ft. +4ft. +0.5 ft. = 5.0ft "2 • Toe Pressure = 4996.8 # /5.0ft "2• (1 +(6'0.439 ft. I( 0.5 ft. +4 ft. +0.5 ft. )))= 1526.1psf Heel Pressure = 4996.8 # /5.0f1 "2• (1- (6 ft. /(0.5 ft. +4 ft. +0.5 ft. )))= 472.6psf F.S. Overturning = 14990.4 #-ft. / 4693.3 #-ft. = 3.19 F.S. Sliding = 4021.4 # / 2668.1 # = 1.51 d2 = (7ft. + 1ft.)/ 4 = 1.75 ft. H3= 4ft. /4= 1.35 ft. H 0 . 5 ft./ 4 ) + ( 0 . 5 ft.' 4 /(((( (1) "2 + ( 4 ) "2) "0.5)'4))) +0.5ft. /(((1) "2 +( "2) "0.5)•4)) =0.5ft. Batter Angle = arctan (1 / 4 ) • 180 / PI = 14.04 degrees vil PROF J okGINE /o 14743 / OREGON v 4N ,9 9 � �4'N ES2 D. • IMe ik\ -� 30 -0 i • • . . . 4c1. (--- \ .: .; - : .. Alai ,.. ..„.• , o,(,...- - ... . ,.. L (0? /r " ?- - � -- J J ` ` • • j 1 � ����;; :. C.G. • 3. S ' -4_•. 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