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Home My WebLink AboutSpecial Inspection Field Test & Inspection Report 2000-8-24 Au~ 25 00 07:03a Ri~ '08/25/2000 06:34 541b84~. Valle~ Builders Inc 541 367 1638 K & A ENGlNEERINC f'.2 PAGE 02 K & A Engineering. Inc. P.O. 80110524, Eugene, OR 97440 521 Markel St., Suite D, Eugene, OR 97402 (541) 684-11399 Voice (541) 684.9358 FAX August 24, 2000 Greg laf10n River Valley Builders P.O. Box 2041 Corvants, OR 97339 rY 36/7 Subject Building Pad EvaJuaUon I ' Ambleside Meadows, Lots #15'4 and 113 Springfield. Oregon ' ~ Dear Mr. Larkin: ~ /)lL. 2--~ 7/"3 tit j; K & A Engineering, Inc. Is pleased to have this opportunity to provide an evaluation of the suitability of the subject building lots tor construction of foundations for single-family resIdences. Both of these lots have been excavated and prepared for the construction 01 standard cast-in-place concrete strip footings, spread footings, and stem walls. These recommendations are made In accordance with "Excavation and Foundation Requirements for New Strutures on Individual Lets" .establis~d by the City or SprIAgf,~ld~ 1 , " .'. ~ i. ':; ~ . 't'; ; i. . PURPOSE, SCOPE, AND LIMITATIONS The geotechnical engineering services summarized herein ari provided 10 assist River Valley Builders In properly preparing the subject building siles for foundation construction. These services include engineering recommendations to avoid construction on unsuitable soils and quality control of compacted fills only. The scope of our services does not include construction safety precautions, techniques, sequences, or procedures, except as specifically recommended in this.report. Our services should not be interpreted as an environmental assessment of sile conditions. This geotechnical in'Jesllgatlon. analysis. and recommendations meet the standards of care of competent geotechnical engineers providing slmilll' services at the time these services were provided. We do not warrant or guarantee these reconvnendations, site surface, or subsurface conditions. LOT 154 General lot 154 is located on the south side of Ambleslde Drive. 1l1e existing ground surface slopes to the street below at a grade of approximately 10%. Vegetation consists of native grasses. The ground surface (prior to excavation) Is even and uniform across the lot, with no evidence of slidIng. sprirl)S, excessive erosion, or I Ambleside Meadows Subdivision -1" Addition Rug 28 00 0?:19a 08/25/200e 14:18 Riv Valle~ Builders,Inc 541367 1638 541GP Ja K & A ENGlNEERJ~ F-2 PAGE 02 K & A EngIneering, Inc. 2. Soil Unit 3 (SU3) - 1 Vz to 2-feet of grely, damp, finn to stiff, moderately plastIc sills. This soil unit was found near the south end of the excavation, midWay between the east and wes1l1nes ct excavation. 3. Soli Unit 1 (SU1) - 1 Yz to 2-feet of dark brown, mOist 'inn to stiff slits of medium plasllclty. These salls are likely to have a moderately high liquid limit and a moderate to high shrink,lsweU potential, This soil unit was in the areas not occupied by SU2 or SU3, and is identical to the soR unit found on lot 154. Immediately underneath the soil is bedrock (rock unit RU2) consisting of an Undifferentiated tuffaceous sedimentary rock. Unlike the rock unit at lot 154, this malenal appeared to be highly stained and decomposed. The rock has decompOSed to an orange-brown, dense, silly-sand. This untt Is classified as EECO.' ThIs matenal Is stable, non-expansIve, and suitable for placement of foundation loads. Groundwater There Is some evidence or groundwater seepage In the cut for the foundation pad because of the highly-stained state of the decomposed be<tock, However, the residual (decomposed rock) solis have a moderate permeability. Sln1ace Water There is no evidence at surface water concentrated flows or surlace anomalies that might collect SUrface water. Excavation and FoanlfatIon SIte Preparation The soli units above the bedrock were excavated and wasted off-site. All loose soil and rock debris were removed. As much as 2 to 3-feet of angular 6-lnch minus quarry shot-rock was placed at the northeas1 comer where a significant amount of SU2 was removed, and 1 to 1 1,4 -feet of quarry rock was placed elsewhere on the north 'h of the excavation to bring the subgrade to a proper elevation. Finally, four to 6-lnches of a well- graded, angular, crushed aggregate (1 Y~inch minus) was placed on ths enUre bUilding pad and compacted. The density of the crushed aggregate was tested and found to average 102% of maximum relative dry density as determined by ASTM D698. RECOWHdENDATIONS We recommend that the foundation excavation and preparation be approved by thslocal bUllc1lng oHlclal for construction of conventional cast-in.place concrete foundations. In addttlon, we make the following recommendations: 1. Crawl spaces and footings should be drained to the storm water drain system as per standan:l City Specifications, . 2. final gradlno should direct surface draInage away from the structure to the street. and 3. RoOf draInage should be collected and piped to the storm drain system. Thank you forthis opportunity to be of service. Please cal if you have any questions. ~ ~ Michael Remboldt, P.E. PrinCIple Engineer, K & A Englneer1no, Inc. ..: .....-- ~.. /IF 1"~~ ~~ ~~~ ~~ D~NNIS ~~: IiXPIREsI "'-/-r. II ~ I Respectfully. Ambleslde Meadows Meadows lots 154 and 113 Page 3 of 4 August 24, 2000 Rue; 25 00 0?:03a 08/25/2000 e6:34 Riv' Yalle~ Builders Inc 541 ~6? 1638 541r ~J8 K & A ENGlNEEP p.3 PAGE In K & A Engineering, Inc. concentrated surface drainage. We observed excavation 01 this lot on August 11, 2000. Excavation and placement of compacted. engineered fill was completed and Inspected on August 24, 2000. Lithology SOlis on this site consist of approximately 2 to Meet of dark brown, moist, firm to stiff slits of medium plasticity (sOil unit SU1). These soils are likely to have a moderately high liqUid limit and a moderate to high shrink/swell potential. Immediately underneath the soli is bedrock (ROCk Unit RU1) consisting of an undifferentiated tuffaceous sedimentary and volcanic conglomerate. This rock unit Is an Interesting conglomerate of mulll-colored martne siltstone fragments in a matr1x of grayiSh-whne volcanic tuff, Sman marine fossils were observed in this unit. The rock unit appears have a relatively low degree Of weaflerlng, a relative low shear strength. low permeability (Le. few local discontinuities), and a moderate unit weight It was visually classified as BOBO.2 This rock unit appears stable and suitable for foundatiOn loads. Groundwater. There is little evidence of significant groundwater seepage in the cut terUle foundation pad. The rock Is not stained and appeared to have a low moisture content The overlying soil unit was slightly below the plastic limit. SlII1ac:e Wa\8r There Is no evidence of sOOaes water concentrated flows or surface anomalies Ulat might collect surface water. Excantlon and Foundation Site Preparation The soli unit above the bedrock was excavated aro wasted off-site. The pad was stepped with a lower level a\ the north side of the excavation. All loose soli and rock debriS were removed. ApproxImately 1 to 2-'88t of angular 6-toch minus quarry shot-rock was placed in the front (north side) of the excavation \0 bring the subgrade to a proper elevation. Finally, four to 6.inches of a well.graded. angular, crushed aggregate (1 l/2-inch minus) was placed.on the entire building pad and, compa~d. lThe density 01 the crushed aggregate was tested and found to average 103% Of maximum relativ~ dry density as detennined by ASTM 0698. .. . LOT 113 GenIII'Il L0119 is located on the south end of the cul-de-sac at.361h St.. The existing ground surface slopes to the street below at a grade of approximately 5%. vegetation consists of native grasses. The ground surface (prior to excavation) Is even and uniform across the lot, with no evidence of sllding, springs, excessive erosion. or concentrated surface drainage, We observed excavation of this lot on August 22, 2000. Excavation ana placement of compacted, engineered fill was completed and Inspected on August 24.2000 Uthalogy Soils units on thiS site consist of: I 1. Soil Unit 2 (SU2) - Appml<i~ly 2 to 4-feet of a hard tan silty fill placed In the obliteration of an old road. This material was located on the east 113 of the lat, These soils are of an unknown origin Bnd do not appear to be suitable 'Pr construction due to uncertain density non-uniformity. 2 Unified Rock Classification. See Attached, Ambleside Meadows Meadows lots 154 and 113 Page 2 of 3 August 24, 2000 AlJg 25 00 0?:04a I Ri. Vall:e~ 541G8 . I Builders Inc 541 36? 1638 . K~. ~~NGINEER:~ . . - 68/25/213013 06: 34 UNIFIED ROCK CLASSIFICATION' Table 1 - DEGREE OF WEATERING I 1...Bf~~ . \..' .'. .~. .. !ij.I~~~.. :._ - I~~ _. . parOy Decomposed Completely Slate Decomposed (POS) State (CDS) stained State (SITS) I i .C I Ta~le 2 . ESTIMATED STRENGTH I ~~!IJ~.-ndll11lii.li6~m~~ "Rebounds" "Pits" I "Dents" "Craters" Moldable (Elastic) (Tensional) (Compression) (Shears) (Friable) (RQ) {PO) i (DO) (CO) (MQ) >15,000 psj1 8000-15000 pSI' 3000-8000 psi' 1000-3000 psP <1000 psi' >103 Mpa' 55-103 M~' 21-55 Mpa1 7-21 Mpa1 <7 pS~2 A B leD E I I Table 3 - DISCOtfflNUlnES , ~Jj" Solid Solid I (Random (Preferredi Breakage) Brvakage)! (SRB) (SPB) Micro Fresh state (MFS) Visually Fresh S1als (VFS) A o E 8 ol'.! : .l.~~:~: _:J. I ~~4" :,~.t;!~J'wU .~"')l.: i~" 1.:~\(.I.,t:.!.!~:"~: :-.~'J,.. ~ A B Solid (Latenl Planes 01 Separation) (LPS) C Nonlntersecting Open Planes (2-D) Intersection Open Planes (3-D) D E > 160 pc' >2.559fcc A Table 4 ~ UNIT WEIGHT 150-160 ~ 140-150 pef 130-140 pet 2.4-2.55 Q/ec 2.25-2.40 wee 2.10-2.25 glee B leD i Classification Nomenclature: II A-E! I A-E l Strength Discontinuity A-E I WeIght <130 pcr <::2.10 glee E I A-E , Weathering I Douglas A. WlIIiamson. Bulletin of the Assoc. of Engineering Geologists. Vol. XXI No. 3/. pp. 345-354, 1984. 2 Approximate Unconfined CQl11presslve .trenoltl p.? PAGE 07