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Report .f % 4 m? ('67 c t r� i"-d-K4/4-c) • / Engineering, lnc. Real -World Ge•technical Solutions Investigation • Design • Construction Support June 21, 2005 /-1T o' /35 Project No. 03 -8183 Attention; Andy Venture Properties, Inc. 4230 Galewood Street, Suite 100 Lake Oswego, Oregon 97035 Fax No. 503 -670 -9099 RE: SOIL EN A y a , ER'S REVIEW OF FOUNDATION EXCAVATION SUBGRADE LOTS 73 AND 103 SUMMIT RIDGE TIGARD, • EGON References: 1. GeoPacific Engineering Inc., Geotechnical Investigation, Summit Ridge Development, Tigard, Oregon, dated May 12, 2003. 2. GeoPacific Engineering Inc., Soil and Wall Engineer's Summary at Conclusion of Earthwork, Summit Ridge Development — Phase 1, Tigard, Oregon, Revised January 21, 2004 (should state 2005). GeoPacific Engineer, Jim Imbrie, visited the site to review the foundation excavation subgrades for Lots 73, 84, and 103. On Lot 73, the observed native soil is stiff and slope or retaining wall setbacks are not an issue. On Lot 84, the observed engineered fill is very stiff clay with rock and is adequately setback more than 10 feet from a 6 -foot tall rear yard rockery retaining wall. On Lot 103, the observed engineered fill is very stiff clay with rock and is adequately setback aboutl0 feet horizontal from a 9 -foot tall side yard rockery retaining wall. Some mucking may be required if the subgrade is left exposed to wet weather for a long duration, however the current subgrade is considered adequate. Based on our observations, it is our opinion that the current foundation subgrade is suitable for spread foundation support to a maximum allowable bearing pressure of 1,500 psf. Minimum reinforcement has been recommended in the above Reference 2. Our work scope pertains to a geotechnical engineer's foundation excavation review only and the conditions existing and exposed at the time of our site visit. No deck footing, patio, or other appurtenant structure subgrades were observed. Our work was performed to the current local standards of practice. No other warranty is herein expressed or implied. If you have any questions, please call. • Sincerely, GeoPacific Engineering, Inc. _ cr y i,�61N ti" ,, i . ` 1 . 14743 * T - \ OREGON James D. Imbrie, P.E., C.E.G. • -; 44f 23 1 c sc P Geotechnical Engineer 44fes D.. ogee, >7 6 _ o�. 06/21/2005 09:34 50313986705 GEOPACIFIC ENG INC PAGE 01 • GOOF CHM • Enijneerfnp,lne "`', Real -World Geotechnlcal Solutions Investigation • Design • Construction Support June 21, 2005 /15TG2oT'5 — o /35 Project No 03 -818" / g 4gYt 5.514) ,CGUff Attention; Andy Venture Properties, Inc. 4230 Galewood Street, Suite 100 Lake Owego, Oregon 97035 Fax No. 503 -670 -9099 RE; SOIL ENGINEER'S IWVIE1N OI°° FOUNDATION EXCAVATION SUBGRADE LOTS 73, 84, AND 103 SUMMIT RIDGE TIGARD, OREGON References; 1, GeoPaclfic Engineering inc., Geeteohnical Investigation, Summit Ridge Development, Tigard, Oregon, dated May 12, 2003, 2, CcoPocfio Cngineering l . Seii end Wail engineer's summary at Conclusion of Earthwork, Summit Ridge Development — Phase 1, Tigard, Oregon, Revised January 21, 2004 (Should state 2005), GcoPecifio Engineer, Jim Imbrie, visited the site to review the foundation excavation subgrades for Lots 73, 34, and 103. On Lot 73, the observed native soil is stiff and slope or retaining wall setbacks are not an issue. On Lot 84, the observed engineered fill is very stiff clay with rock and IR Adequately setback more than 10 foot from a -foot tall rear yard rockery retaining. wall. On Lot 103, the observed engineered fill is very stiff clay with rock and is adequately setback aboutl0 feet horizontal from a 9 -foot tall side yard rockery retaining wall, Some mucking may be required if the subgrade is left exposed to wet weather for a long duration, however the current subgrade is considered adequate, Based on our observations, it is our opinion that the current foundation subgrade is suitable for spread roundetion support to a maximum allowable bearing pressure of 1,500 psf. Minimum reinforcement has been recommended in the above Reference 2. Our work scope pertains to a geotechnical engineer's foundation excavation review only and the conditions existing and exposed at the time of our site visit. No deck footing, patio, or other appurtenant structure subgrades were observed Oi Ir work was performed to the current local standards of practice, No other warranty is herein expressed or implied. If you have any questions, please call. Sincerely, GeoPacific Engineering, Inc. 4 .40 PR» Q ' 14743 r, OREGON James D. Imbrie, I- C,Is °G, 44 ° ea, t� �� Caeatechnical Engineer . aI q . r � • [UV/ iv,J[niw No. 0336 P. 1 • s� o t � �[hgjpC,Cenpinc���a .eaI -World Gs 4 - technicel &®lotions Investiigat5oa4 a Design Construction Support October 31, 2005 pp Project Rio. 03 -8183 EC E U A � A E Matt Hammack ;`� Landscape Oregon Inc. NOV 1 2005 12200 SW Myslony Rd. • Tualatin, OR 97062 CITY OF TIGARD Fax: 503 692 - 0768 BUILDING DIVISION RE; CORNERSTONE WALL DESIGN SU BAIT RIDGE DEVELOP' ENT e LIT 103 TIGARD, OREGON Reference: GeoPacific Engineering Inc., Geotechnical Engineering Report, Summit Ridge Development, Washington County, Oregon, dated May 12, 2003. Enclosed are our recommended design and construction details for the Cornerstone segmental retaining wall proposed in the rear of Lot 103 (12994 SW Black Walnut Street) of the Summit Ridge Development. Based on the plan provided we understand the wall was planned to be a maximum of 7 feet in retained height. The preliminary plan (see Figure 1) and our site visit indicates the wall was planned a distance of 8 to 9 feet from the existing rockery retaining wall near the west property line and then parallel to and 40 feet from the back of the house. The slope below the wall was planned at a 2H :1V. The walls will support primary engineered fill. Following a review of the proposed plans and our site visit on October 28, 2005, we recommend the wall locations be revised such that the face of the south wall by a distance of 36 feet from the back of the house and the face of the west wall be a distance of 4 feet east of the western side of the house (see Figure 1). These recommendations have two beneficial effects. First, the additional surcharge as a result of the proposed retaining walls are decreased and located farther from the existing rockery wall to the west and the existing 2:1 slope to the south. Second, the revised wall locations provide a 4' flat bench at the base of the walls resulting in additional factor of safety for bearing support and global stability. The enclosed wall design is for an 8ft wall to compensate for the 1 to 2 feet of soft soils encountered near the southwest corner of the proposed wall. These soft soils must be removed to stiff, competent soil prior to wall construction. The engineered walls were designed using F100 Cornerstone blocks (8 "x18 "x12 "). Retaining walls should be embedded a minimum of 1 foot below finished grade. Subgrade soils should consist of stiff native soils or engineered fill and the walls should be founded on a crushed rock leveling pad a minimum of 6 inches thick. The walls should be battered to 4.5 degrees, which corresponds to manufacturer's recommendations. • The reinforced backfill one may consist of crushed rock (3/4 " -0 aggregate), reject rock, or recycled concrete with a maximum cleat size of 1.5 inch and no more than 15% fines end compacted to at least 95% of Standard Proctor (ASTM D698). To avoid bulging of the wall facing, large equipment should not be used within 2 feet of blocks and compaction against the back of wall should be P�9a spy 9urharn and — Ponaand, Oregon 97226 P ®l (M) 6904A45 Tan a 598 -8705 No. Mb r'. 2 Project No. 03 -8183 Summit Ridge - Cornerstone Wall achieved using a hand held vibratory plate compactor. Block infill should consist of % " -0 crushed rock. Geogrids should be spaced according to the attached wall details. The bottom geogrid should be placed between the second and third block and subsequent geogrids should be spaced every two blocks vertically up to and including the geogrid between the sixth and seventh block. Above this point, geogrids should be spaced every three blocks vertically. To provide an adequate factor of safety against the top two blocks overturning, a 3 foot geogrid should also be placed beneath the top block. Geogrid length should be equal 80% of the retained height of the wall (not including embedment depth). Geogrid length is measured from the face of wall. Geogrid should consist of Miragrid 3XT or approved equivalent geotextile with a minimum ultimate tensile strength of 3,000 lbs /ft. The grids should be rolled out perpendicular to the face of the wall and not along the wall face. Adequate drainage behind and beneath the wall is critical to wall performance. A minimum 12 -inch thickness (measured horizontally) of free - draining gravel, or drain rock, should be placed between the back of the wall facing units and backfill soils. A subsurface drain consisting of 4 -inch diameter, perforated, Schedule 40 PVC or ADS Highway Grade pipe embedded in a clean, free - draining gravel ordrain rock, should be placed behind the bottom of the wall as shown on Figure 2. The drainpipe and surrounding drain rock should be wrapped in non - woven geotextile (Mirafi 140N, or approved equivalent) to minimize the potential for clogging and/or ground loss due to piping. Water collected from the drains should be directed to the storm system or other suitable outlet. Based on the attached calculations, the proposed walls will have adequate factors of safety against sliding, overturning, bearing capacity failure, internal failure, and facing failure provided that our recommendations for wall construction are followed. Concrete masonry unit blocks and geogrids should be installed per the manufacturer's instructions. GeoPacific should perform a special inspection for the construction of the designed Cornerstone walls including subgrade and backcut inspection, overexcavation requirements, embedment, wall batter, geogrid placement, and backfill compaction. We trust this information meets your needs. Please call if you have any questions. Sincerely, GeoPaciiflc Oneering, Inc. 4. ka �N o ts s 4o t o 1474.3 James D. lmbrie, RE., C.E.G v' 1- -o .. Geotechnical Engineer Attachments: Figure 1 - Retaining Wall Plan Figure 2 -- Cornerstone Wall Typical Detail (8 ft) Design Calculations - 8 ft Static Conditions 8 ft Seismic Conditions Page 2 • _ . _ _ . . . — . .. 'VII. UJOU r. 1 41 sr.;i 7312 SW Durham Road REAONN ,sawl4 Penland, Or on egon 224 T11NG WALL PLA . 1 nItagralrfa6 Tel 503.598.6445 Fax 503.596.8705 • • . 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Not 'to scale Note: The location of ail geoteohnical information is approuirnato Date: 10/31/05 Drawn by: PBR E , Project: Summit Ridge - Lot 103 i Job Kb: 03-8183 RGURE I _ Tigard, Oregon .. _ -.._ it V. VJVU I. Y I _ ' 47- 7312 SW Durham Road COR ER T •i `i 1I�L 11 II ad®ll, ° <_ 110.0 Portland, Oregon 97224 , ,7- - t -- ----- --- r Tel 503 590.8445 Fax: 503.598,8705 � �9C��(� ®��' 8� ° il A GEOTEQHN ICAL . ` .� REPORT 9S REODU1RF BEFORE THE F ©C3TI 1 Q �(�iPEC�TEQN IS APF'RQ1 fit.' { . Wlinirnuin S'•' Low : Permeability Soil r s I Cornerstone '� ...Ir. e - - - ll r 1, K! E' F100 Units 3 Feel Geogrid 0 .� S� a eee_oe_ ey Reinforced Dackfill Zone - Crushed 1 . d Y `3 Rock, Reject Rock or Recycled Concrete I 1 gif Compacted to 95t' of Standard Proctor 1 I IMO PrAMIM .4 '�i r'a Geo;rid Min.Len = (0.8)H 1 ( rmr ` __________= evee Compacted E ,t j Engineered bill 8' Maximum ' , y 1, Weil Weight (1•1)4 ' ?c; k i Unit Drainage Fill 1 " (; 3/4" Crushed Rock `` � q r� r I ; �, ;' ;'ia 12 Inch Min i r 4 , � r ° I ',. Limit of Excavation ' (Contractor Responsible x. .om e_ee_____me moo =m I for Stable Backcut) .; Geogrid Type e {Y1ir€lgdd 3XT ' �- ?iv ti or Approved Equivalent x y, 1+, ' "t.. 0 •1 4FtMin � + ; ..,, ----- - - - - - - - - - ------- j K^r c> e 1 Fl Min _.� ' - - �` 4' Drain � � � 1 Y , ,, „ .u rr •. ,:� 1. Approved e_ r.. + _ • , Drain Rock I Unreinforced Concrete or Crushed Rock NOTES: Leveling Pad Not to Scale 1, Wall Height (H) is the retained height (not including embedment). 2, Minimum wall embedment is 12 inches for walls up to 0 feel in retained height. 3. Unit core fill, leveling pad, and any additional drainage materials shall consist of 3/4" - 0 crushed aggregate. 4. Backfill in reinforced zone to consist of crushed rock, reject rock or recycled concrete with maximum clast size of 1.5" and I no more than 15% fines and approved by the geotechnical engineer. 0 Geotechnical En ineer should review sub trade soils and t slo . e be ': t .,. Geogri s must be of appropnate type and length pert e design calculations. Date: 10/31/05 t 7. Finish grade must provide positive drainage. i , Drawn by: PER I �..RC .ut?s..'.... :� �..r,:..r +1�.-- u.i�:s._- �aarnie cm•�ss�m, 1 I Project: Summit Ridge - Lot 103 r I 1 i i Project No. 03 =8183 j FIGURE 2 Tigard, Oregon , i