The URL can be used to link to this page

Geotech Report.pdfLIU & ASSOCIATES, INC. Geotechnicall E nginee-ring Engineering GeoF--gy September 28, X011 Mr. Richard Stuart 1109 — 12"' Avenue North Unionds. WA 98020 Dear Mr. Stuart: Subject- Geotechnicul Investigation and Desion Precast Concrete Block Wall for Driveway Stabilization Stuart Residence 1109-12 h Avenue North Edmonds. Washington. 14- A Job No. 11 -057 INTRODUCTION Earth Scie"Ice The reckon! Nvall along the west side of the paved driveway on your propcm,, located at the above address in Edmonds, W.i5hingnon, failed recently. We understand that you plan to build a precast concrete block wall to replace this failed rockery wall in order to stabilize the drivQwa-v. '�t YOUr request, we have completed -a peoteefinical investigation and performed a design for the I Z� I Z-1 proposed block wall. Presented in this report are our findings of the subsurface conditiom, in the, area and our design of the proposed block wall. PROPOSED BLOCK WALL Your contractor infornied us that removal ofthe failed rockery w y all -will require use officavy equipment .v-hicli could damage the pavement and destabilize the existing driveway and put the. safety of -%vorkers,, at risk. He reconiniends that the stones of the rockery wall be left in place. We conUlr with this assessment and recommend the rockery stones be let! in place w-herever possible, with the, voids between the rockery stones tilled with 7/8-incli crushed rock densified to a non-�, ielding state with a concrete vibrator after disturbed soil between rockery stones is removed as, much as possible, 41� 19213 Kentake Place NE - Kenmore, Washington 9802 Phono (426) 483-9134 - Fax (426) 486-2746 tt G8. September 23.20>11 Precast Concrete Block Wall— Stuart Residence L&A Job No, 11-057 Pa�,e 2 The proposed precast concrete black wall )gill be till to about 12 feet tall. A block wall of this height \\ill rewire 00 id Mesh imbedded in the backfill of the wall to achieve long-term stability. Structural fill of selected material will be required to backfill the block, :,all. A peribrated PVC pipe drain line installed ;along the base behind tlrc wall .will be required to collect surface runoff and groundwater Howl—no towards the wall, Water collected in the block wall drain line should be tightlined to discharge saheb into a storirl sewer or dispersed through a spreader pipe over a relatively flat and well -vegetated area to not cause erosion problem. SITE COND1"IIONS Surface Conditions `I'hte general location of the strbject residence site is shown on Plate 1 —Vicinity lap. It is situate on the upper portion (if a moderate to steep, avesterly-declirtin hillside. For Otn- USO in this investigation, you provided us tivAh a topographic surrey Plan of the site shown on Plane 2, According Lo this plat, a relatively fiat bench area lies in about the eastern two fifths of the site where a house and a paved driveNvay are located.'Linin�� the west side of the drivewav is a rockcry wall «-height had failed recently and is to be replaced with a precast concrete block wall. From the base of this rockery wall out about 17 to 13 fest to the west is a gently sloped bench area declined `graduall> to an existing concrete block wall less than a feat tall; Below this concrete v4all is a steep slope descending 11. about 500ero grade or more LoNv crds a relatively lcvel bench area along the west boundary cif the site. The bench area at the base of the rockery wall is dotted by scattered voting ornamental trees. The steep slope Nvest of the short con. crete wall is landscaped with flower plants ant! shrubs. with the .est boundaryarea of the; site dotted by tall mature evergreen tree. LILT & ASSOCIATES, INC. September ?8.2011 Precast Concrete Block Wall — Stuart Residence I.&A Job No. 1 t -0 i l'a�c Geologic Setting The t:reologicpian (it' the Fdnionds Fast—and Part of the Edmonds Fest rangles. W aslungto , by James P.-Mittard, published by €;. S. Geological Survey in 1953, was referenced liar the veolo-its .and soil conditions at the residence site. According to this publication, the sa:arlicial Soil units bare mapped as a Vashota till. soil Unit (Qvt) within and around the residence: site underlain by an Advancc: Outwash Soil unit (Qva) on the steep slopc to the west of the site. The Vashon Till soil unit vtias plowed directly under glacial ice &Uin+; the most recent glacial period as the glacier advanced over an eroded, irregular surface of older 11ornacations and sediments. It is c-crnal oc eel of a mixture of unsorted clay, silt, sand, gravel, and scattcrcd cobble: and boulder. The Vashon till soil over the top two to l;aur Leet is normally weathered to a medium -dense st;ate, and is moderately permeable and compressible. The underlying fresh till sail is eery dense, and is cominonl.y° referred to as "hard pan". `1'he, fresh till deposits possess the; strength of low -`rade concrete and edit stand in steep natural lopes or nimi-make cutwi tisr as long, period, and are practically impervious to stornnvvater infiltration, If remained tandisrtarbed and well -drained, the fresh till sails can provide excellent: foundation support to Structures with lithe settlement expcetcd, The adv -race outvv<ash ~aril unit, map plod on, the hillside below the, subject residence sitc. is composed ol': tratilicd staid and 07a -vel with v=ery minor amount of silt and c lay, deposited by the meltwater of advancing glacial ic;c of the last gIaacier- Due to their 'generally granular composition, the advance outwash deposits tare rel' moderately hic-la permeability and dratini rairk well. The advance csutwash deposits haat been glacially overridden and are generally dense to very dense in their natural, undisturbed state, except the soil in the top 2 to 4 feet which is nortnally weathered tai) a lcaci:ge to meth rn-dense stat. The advance ouivvasdi deposits can stand in steep cants or natural slopes for extended period kvhen undisturbed. Vr'here exposed on slopes with poor vegetation cover and subjected to storm runoff tar groundwater seepage. the aadv<rnc ec September 28, 2011 Precast Concrete Block Wall - Stuart Residence L&A Job No, 11-057 Page 4 outsNash deposits can be gradually eroded and may slough and redeposit to a flatter inclination, The underlying fresh advance outwash deposits in their native, undisturbed state can provide good foundation -support With liatesettlernent expected !'or light to P1OderMe1VheaVV StTLIOUT,-S. Soil Condition We conducted a iubsurface exploration on a site located at 1xx - 121il'Avet we Nionli in Hinionds (hercinafter referred to as the '*Refe-,ence Site"), a short distance south of the subject residence site. Both the Reterence Site and the subject residence site are mapped within the same Vashon till sail LIDit according to the above -referenced geologic map, To[ pits, excavated on the C- , t7 Refierence Site encountered light -gray Fr"h till deposit of very -dense, gravelly, silty (inc to medium sand -, iib occasional cobble at depths Worn 0,'17 to 3.0 feet. We expect the soil condition at the subject residence site to be similar to that at theReference Site. We probe the soil condition in the gt"InLlv sloped bench area at the becte oil' the failed rockery scall bN, tnanually pushin- a steel T -bar into the OroLffl& The steel T -bar could penetrate no more than 2 and our ground probing' result, it is �.O t`eet deep. Based on the above -reverenced lleololTiC III ?:- -- ap oar opinion that the bench area at the base of the failed rGckeii- wall on which the proposed block wall is to be installed is underlain at shallow depth by very -dense fresh till soiL Groundwater Condition The fresh till deposit,,,, underlying the bench arta aL the ba.w of the failed rockery wall at shallow depth is of extremely to permeability: Sionn runoff infiltrating into the surficial more pemicable soil would perch on the surface of the undeflVing fresh tilt soil. This near-surt "ace perched grroundwater may completely dry up during the dnrer slimmer and tall nionth.s. During the wet winter and early spring. the near-sur(4L.,e perched groundwater would acMmulatc and flow laterally along the SLI&ICO of the underlyim, I rres I h Lill soil and Nvould seep into the LIU & ASSOCIATES, INC. September 28, 2011 Precast Concrete Block Wall — Stuart Residence L Job No. 11 -057 Noe 5 Z, Moderately penneable advance outwash soil where it is in contact with the till soil on the hillside, below the _subject Site. GEOLOGICHAZARDS AND N11T1GA'r10Nr Landslide Hazard About the western Dalt of the residence site is of steep slope at 40% grade or more. The bench area at the base (if the Cailed rockery wall on �vhic.h the block wall is Lo be constructed is underlain atshalhm; depth by very -dense fresh till soil of high shear streiiL)th, On the steep slope bey-ond the -subject site to the West'. the Vashon Lill soil unit is underlain by dense to very -dense advance out�vasb soil of moderately -high to high shear strength, Both soil units have 1�igh resistance against slope failure. Therefore, The potential fior deep-seated landslides to OCCUT on the subjcci residence site or the hillside immediately below it should tie minimal., provided the recommendations, in this report are fully implemented and corn lied with during construction. I p Erosion Mvvzard The thickness ol'the surficial topsoil and weathered soil over the bench area at the base of the ('ailed rockery wall is thin. Thesovveak surficial soils are cif` low resistance -while the underIvine, :P fresh till soil is or hii2h resistance against erosion. Thcre is an outside chance that erosion may occur in the �veaker sufflicial soils over the bench area and the adjacent steep slope if they are . devoid of veoctation cover and overly saturated. Progressive erosion can lead to shallow, skill - type mudflows on the slopes. To nijtigate SUCh- erosion hazard, veuetatiori outside of construction hinits should be preserved and maintained and exposed ground should be covered with plastic tarp, arequired. for protection al, i gamst erosic. nn, Unpaved exposed finished ground resulted from construction activities should be re -seeded and re -vegetated as soon as possible. F-1 Concentrated storinwater should not be disehaqgcd uncontrolled onto the ground within the site. Storniwater over impervious surfaces, such as root"Is and paved drivvway, should be captured by LI U & ASSOCIATES, INC. September 28.2011 Precast Concrete Block Wall --Stuart Residence L&A Job -_,NTo. 11-05 i Page 6 underground drain line systern,,i connected to roof downspouts or by catch basinj installed in payed driveway. A curb or line bump should be installed along. the western edge of the exisiing, paved drivew4y� as required, tokeep runoff on the drivcwaY from spilling onto the backl'ill ol'the concrete block wall. A drain line should be installed aloe -0 the base behind the proposed block wall to collect surface runoff and groundwater flowing toNvards the block wall, Water collected in the above drain line systems should he ti_ghtlined to discharge into a storm sewer or a suitable storinwater disposal facility systcm, such as a spreader pipe system. Seismic Hazard The Puget Sound reuion is in an active seismic, zone, The residence site is underlain aL shallow depth by veiy-dense 1'resh fill deposits of very -high shcLV strength. Therefore, the potential 661 - seismic hazw-ds, such as landslides, liqllefaetion. lateral soil spreading, It) OCCUY on the situ should be minimal if the erosion mitigation, drainage control, site stabilization measure,-, rcconunended in thi-,i report are fully implefliented. The proposed block Nvall, howevc-r. should be designed liar seismic forces induced based on a 100 -year seismic event with a maximum peak ground acceleration of 0_3(g (o - gravitational accele-ration). This maxitnuni peak ,round acceleration may be a4justed for the design of the block wall according to its Jlexibilit), and the non -unison movernent of the blocks during earthquake,,. 2� RECOMMEN-DAI'l () NS General Our proposed alignment of the block wall is shown on Plate), We recommend the block wall be constructed of Keystone StanduTd blinks (8 -inch high X. 18 -inch wide x 21.5 inch deep). As .shown on Plate 4 — Concrete Block Wall Typical Section. the block wall should lia:vc geogrid mesh reinforcement embedded in its backfill, except where the wall is no more than 4 feet tall. A drain line should be provided along, the base behind the wall. 'rhe wall should bc fininded on a minimum 6 -inch laver, T`8 -inch crushed rock, leveling base, placed over firma, undisturbed. fli-11i LIU & ASSOCIATES, INC. September 2 8. 2 011 11recast Concrete Block Wall — Stuart Residence L Job No. H -057 Paso 7 C7 bearing soil. Loose and disturbed soils, if any, within the keyway trench should be over - excavated and replaced with compacted structural rill. A vertical drainage blanket, consisting or clean 7/8 -inch crushed rock. at ]cast 12 inches thick horizontally, should be placed against the back of the blocks. This drainage blanket should be hydraulically connected to the wall drain line at the base. Compacted structural fill should be tised to backfill the wall beyond the vertical drainage blanket, Z:7 Design Soil Parameters The proposed precast concrete block wall varies from Linder 2 fieet to about 12.0 IM tall. We recommend that the wall be designed for a hilly drained condition In accordance with the lbllo�ving soil perimeters. - The block wall should be designed for as minlITILLM factor• Of 1.5 ayain,--.t s-liding, failure, 1.7 against overaiming flailure and 2.0 auainst l'oundation bearing failure Linder the static loading condition. The Ptioct Sound re ,ion is in an active seismic zone and the block wall should also be desigried Linder the seismic loading condition l'or a 100 -year seismic event- The peak ground acceleration l'or such an event in the Puget Sound region is about 0.3g, (g am gravitational acceleration), The block wall, however, are built with interlocking concrete blocks with some flexibility, and the blocks do not move in unison during carthquakes, Therelbre, Fier design of the block wall under the seism -c loading condition, the ground acceleration may be reduced to 0.2g. The block Nvatl should desi6med for a factor of safety, of at least 1.1 against sliding failure, 1,15 against LI U` & ASSOCIATES, INC. Reinforced Retained Foundation T,Qvefing Soils Soils Soils Rock Base I Init Weight, r.. pef 1130 125 1-25 Anl,,,le of Internal Friction: 36 3 4 34 40 �, degrees Cohesion, C'. psf 0 0 0 The block wall should be designed for as minlITILLM factor• Of 1.5 ayain,--.t s-liding, failure, 1.7 against overaiming flailure and 2.0 auainst l'oundation bearing failure Linder the static loading condition. The Ptioct Sound re ,ion is in an active seismic zone and the block wall should also be desigried Linder the seismic loading condition l'or a 100 -year seismic event- The peak ground acceleration l'or such an event in the Puget Sound region is about 0.3g, (g am gravitational acceleration), The block wall, however, are built with interlocking concrete blocks with some flexibility, and the blocks do not move in unison during carthquakes, Therelbre, Fier design of the block wall under the seism -c loading condition, the ground acceleration may be reduced to 0.2g. The block Nvatl should desi6med for a factor of safety, of at least 1.1 against sliding failure, 1,15 against LI U` & ASSOCIATES, INC. September 28- 2011 Precast Concrete Block Wall — Stuart Residence L&A Job No. 11-057 Page 8 C� overturninay failure and 1.5 against lbundation bearing failure under the seismic loading Wall Drainage A nunimurn 6 -inch, perforated, rigid, PVC drain line wrapped in a non -woven filter fabric sock should be laid in the kc-,,vay trench behind the base.-COLIrsc blocks, embedded in the CrWshcd rock - base course. The bottom of keywUy trench and the drain line should have sufficient slope (0.5 percent rnininium) to ocnerate flow by gravity. The drain pipe should be tightlined from a low point at about the inid-length of the wall to discharge into a spreader pipe system over a well- egetaLcd area on the slope below. A vertical drainage blanket, constructed of clean 71/8 -inch crushed rock, Nvith a hoTizontal thickness o(' at least 12 inches, should Lv placed against the back cel' the blocks. This vertical drainaze blanket should be livdraullcally connected to the drain line at the base behind the wall. The wall backfill behind the vertical drainage blanket should consist oCconwacted structural fill, Spreader Pipe Dispersion System Water collected in the block wall drain line should be, tigh , dined to discharge into a storm scw-er. If no storm sewer istivalfable, then water in the block wall drain line may be dispened through a spreader pipe system over a relatively level and area at least 15 feet awav from the block wall. A typical section of this spreader pipe system is shoN,n on Plate 5. The spreader pipe systeni ,,hould be composed of 6 -inch diameter by at le=ast 30 -(bot long, perforated, rip -id. PVC pipe, set level ai about 2 to 5 feet above the ground surface., This perforated PVC pipe should be supported on and anchored to 22 -inch -diameter, .schedule 80 (2,375 -ii ch outside diameter by 0.218 -inch Nvall). steel pipe piles, spaced at iio more than 9 Ceet on centers, driven at least 5 feet into the ground, as shown on Plate 6. The above -grade portion of the tightline firorn the block wait drain tine. traversinly down the slope and connected to the spreader pipe, should also be C LIU & ASSOCIATES, INC. September 2S; 2) 011 Precast Concrete Block Wall — Stuart Residence L& A Job iso. 11 -05 7 Page 9 supported on and wichored to 2 -inch steel pipe pites. All steel member of the support system should be painted or gyalvandzed for long-term corrosion pi-owetiOn' Water discbOrged through the spreader pipe will evaporate into the ambience, absorbed by the root systern of the vegiation on the slope, and with a small ftaction inriltrate into the guound, Water fioNving out of the spreader pipe will be at such low velocity it would not cause any erosion problem on the slope, Wall Rachfill Backfill behind the vertical drainage blanket of the block wall should consist of con)pacted st-rucLuTal rill. Structural fill should be composed of clean, granular soils free of orgailics and debris. with particles no larger than three: inctics. Onssite clean till or advance outwas'h sol) meeting the above requirements may be used as sMICLUral fill. Structural fill should have a moisture convent within one percent of its optimum moisure content at the time of placement. The optimum moisture coriteni,.; the water content in the soil that enables the soil to be compacted to the highest dry density for a given compaction OTOM Imported material to be used as SIRICtural fill, should be clean, granular soils containing no more Lhan 5 perecat by weight finer than the No. 200 sieve based on the fraction. of the material passing No. 4 sieve. Structural fill should be placed in tills no more than 10 inches thick in its loose State, with each lift compacted to at least 92'Ma of the maxinium dry density determined by A', -','I'M D1557 (Modified Proctor N-lethod). Setback of Block Wall Since the failed rocker} wall is to be left in place �,N�herever possible. The alignment of the proposed concrete block wall will have to be set at about 8 fleet atom the too of the rockery wall in order to accon-n-nodate the -eoorid rnesh to he embedded in the wall backfill. This NvIll put the z C wall tip (o about 18 feet from the edge of the existing paved driveway and will be. about 10 feet LIU & ASSOCIATES, INC. September 28.201 1 Precast Conexete Block Wall — Stuart Residence 1,&A Job No. l 1-057 Page 10 from the top of slope at 40�/�Y or more grade west of the existing concrete block wall. The residence site, including the bench area west of failed rockety NVIIIII on wfich the proposed block wall is to be b u i It, i,,; underlain by very -dense fresh till soil at sh I allo�N, d I epth I underlain I b I v dense to ,v -en! -dense advance outwash soil, Both types oaf soils are of 'hio, i she'191 strength acid are highly resistant against slope 1`4ililTeS. Therefore, it is our opirt on that the 10 feet setback from the top of the adjacent steep slope of 40% or more grade should be adequate to maintain long-term. stability of the proposed block ivall- STABILITY ANALYSES AND DESIGN OF BLOCK WALL S "'RWall version 1'212 computer program, developed by National Concrete Masonry Association, was used in our stability analyses ol'the Precast concrete 1-.,Ioek wall. The results of the analyses are presented under APPENDIX attached to this report. Our dcsiggn of the precast concrete block wall is shovm on the 1`61 lowing plates attached hereto: Plate 3 —Block Wall I _avout Nan Platte 4 — Concrete Block 1Vall Typical Section Plate 5 — Spreader Pipe System Plate 6 - G- eogrrid.\-lesh Schedule Plate 7 Silt Fence Detail Plate 8 General Notes. and Plate 9 — General Notes CONSTRUICTION RE( -,'ON] MEN DATIONS' Site Preparation and General Gtrading Vegetation within constiuction Imihs ofthe block wall and wall backfill should be cleared and roots thoroughly grubbed. Topsoil atid surficial weak soils within the block �valt and wall LI .T & ASSOCIATES, INC. September 28, 20 11 Precast Concrete Block Wall — Stuart Residence 1.&A.loh No. 11-03 r Pao I I backfill should be stripped do -vv -n to denSe undisturbed till soil, Over -excavation down to fitrin bearing soil should be backfilled with conipactcd structural fill. Temporary Erosion Control zl1 silt fence should be erected along the downhill side of' the construction area. as required, to keep sediment fironi being k-,.ashed down to adjacent properties. "I'lic detail of the silt fence is presented on Plate 7. The bottom of the filter fabric should be anchored in a trench filled with gravel. A layer of clean quarry spalls should be placed over areas of frequent construction trallic, as required. to protect subgrade soil froth disturbance by construction traffic. Areas of frequent conSIMC6011 traffic should be protected �vith a laver of 2 -to -4 -inch rock spalls. f.,.xcavated spoil soil Lmsuitable for use as structural fill ;hould be hauled out of the site as soon as possible. Spoil soil to be temporal): Stockpiled on site and exposed _ground should be covered with plastic tarp and securelN vvcighted do,.va with sandba-cvs for erosion Protection. Ke-,ivay. Trench The keNivav trench 6(ir the block Nvaill shotdd he cut into native, undisturbed, firm bearing soil, capable of rendering an allowable bearing pressure of at least 3,000 psf. The soil exposed at bottom of the keyway trench should be compacted to a non-yieldinU state with a vibratoT compac(or, Over-cxcavation of' unsuitable weak soils at bottom of ked-wav trench should be backrilled wftdi compacted structural fill, A niiniTnurn 6 -inch laver of 7F8 -inch -minus crushed rock leveling basc. compacted to a non -yielding state, should be placed over the subgrade soil to iapport the, block wall, The base-coLLrsc blocks are to be placed on this crushed rock base with art einbeclmenl at ],east 8 inches below the adjUCM I'mish grade in front of the block wall. 'rho r, precast concrete blocks should be stacked thj itly against one aTiother. - LIU & ASSOCIATES, INC. September 28. 2011 Precast Concrete Block Wall -- Stuart Residence 1,&_A Joh No, I I -Q57 Noe 12) Geogrid Nlesh Each layer of geogrid mesh should be laid (in level backfill surface, with one end secareiy anchored between txvo Tow's of blocks, stretched tight. and the other end stale -ed down prior to the placement of the next lift ofwall backfill. Overlaps of ge0grid mesh in the direction of the %v'all alit nment should he at Icast 12 inches, overlaps in the direction perpendicular to the vaall alignment should not be allowed. Permancnt Erosion Control Areas disturbed and devoid of vegetation by construction activities should be seeded, vegetated and landscaped as soon as possible for erosion protection. The seeded and vegetated areas should be covcred with a layer of clear plastic tarp, is required, until the -vegetation is Ball",, established. CLOSURE ti�,'cars: pleased tea beoCscrvicett)vt-)uort this pr(ijet. Please feel free to callus if you have an, qtiestluiiS regarding this report or need further consultation. Y�iurs very truly, LTT ' j4w ASSOCIATES. INC. J; S, (Julian) Lia, Ph6l7, P.P. Consulting Gcotechnical Engineer c;1 Attachnients, 1. Plates I throuvil 9 2. APPENDIX — Precast Concrete Block Wall Stabilit`-- Analyses LIU & ASSOCIATES, INC. I VICINITY MAP lKX0& ASSOCIATES, INC. STUART RESIDENCE 1109 - 12TH AVENUE NORTH ueom�hnicai 'eoQmowin0Geology ' Earth 3cieoc�e EDMONDS, WASHINGTON 0 ---------- JOB NO, 11-057 1 DATE 911712011 PLAT E - w4l'W m 1;20t 9 0 V �X 4 �1 0-CY, T LILA & ASSOCIATES, INC. Geo tecimca-I.Engiveering - Engineering Ge�.oqy _Earth Science ' X*T 0 SITE PLAN STUART RESIDENCE 1109 - 12TH AVENUE NORTH EDMONDS, WASHINGTON 11-057 1 DATE 911712011 1 PLATE v- ' zi LILA & ASSOCIATES, INC. Geo tecimca-I.Engiveering - Engineering Ge�.oqy _Earth Science ' X*T 0 SITE PLAN STUART RESIDENCE 1109 - 12TH AVENUE NORTH EDMONDS, WASHINGTON 11-057 1 DATE 911712011 1 PLATE E s n 0 +4, CSI IH 9*0 3 Ji 13 t k 4 �- 11 19 I 3� sH ' $ P-1 v t E � �f" (�} :. '9 � d i � l k !r T�\' i .: # zi .9 s f� scl - n ilk= / Y T"Od 3LVAldej -Z -J / CONCRETE BLOCK WALL LAYOUT PLAN L11i & ASSOCIATES, INC. STUART RESIDENCE 1109 - 12TH AVENUE NORTH GeotechniGal Enginee.ing Engineesin} Geology • Earth Soenoe EDMONDS, WASHINGTON JOB flo. 11-057 DATE _9/22201. 1_ 1 PLATE 3 -Z .3 7C3 �z A Nl� I 8 LII & ASSOCIATES, INC. Gootechnic-al Engifiming - Engin ring g Geology - Earth Setence TYPICAL SECTION - CONCRETE BLOCK WALL STUART RESIDENCE 1109 - 12TH AVENUE NORTH EDMONDS, WASHINGTON JOB NO, 11-067 1 DATE 9128/2011 1 PLATE Nl� 8 LII & ASSOCIATES, INC. Gootechnic-al Engifiming - Engin ring g Geology - Earth Setence TYPICAL SECTION - CONCRETE BLOCK WALL STUART RESIDENCE 1109 - 12TH AVENUE NORTH EDMONDS, WASHINGTON JOB NO, 11-067 1 DATE 9128/2011 1 PLATE `f4>! . p plc. TlC� d�T L N e IIZI14 a -I ALT pipe 6 MIN. � qc p 4 g d Et 4- Ti6qTLItle S''' , 1 e' p d L) FPO KT TOP vi SPREADER PIPE SYSTEM MLI & SSS TE , INC; STUART RESIDENCE 1109 -12TH AVENUE NORTH Geutedmica? Ee inrinEr eering Geoiogy • Eanh Sc(em;t �3. m �._ _ EDMONCiS, WASHINGTON ,SOB NC. 11-067 DATE 91181201 � FILTER FABRI-IC— S,ccu'RED TO 2' \ 2" '44 GA, FABRIC EQUAL 2' X 2' WOOD OR COUIVALENT 0 cu PLACE 3/4'-1,5' WASHED GRAVEL 74N THE TRE NKCH AND ON' BOTH SIDES OF FII. `ER FAB-7;L'C FFNCE I-!',' TH7" SURFACE CG N TIRA C T D.R EVE R ViLL t-JAINTAP4IN REPLACE PRD,,F,r, E N' CON'T'RDI- �S! RAW BALES M INSURE , i- SIU Geaechricaj Enqteering - Engineoring Geology - Earth $--'Onco FILTER FABRIC KZ�TERIAL IN COMINCUS RULLS, US-- STAPUES OR WTPZ' RTM%S TO Al fACH FABR11C I'D %�IRE, FIESH' FSUF`Pi- r- J� -IRT FENC"E TO SUFFORT Flt, -,F -R FAWIC- 'E— A BURY BOTM!I" MATE-ki,'iL Lj E X 2' W,573D' EQU7VALD',,� CT iTY INSPECT ON,7-ECUIRI-T) 011N ,:LL EROSION C0N-PL"iL. 1- DTHER WORK CAN BFC171`41' SILT FENCE DETAIL STUART RESIDENCE 11019 - 12TH AVENUE NORTH EDMONDS, WASHINGTON 3 NO- 11-057 F -DATE 9/18/2011 1 1. SCOPEOFWORK Contractor shall provide material, equipment, labor and 'tools to complete the Precast concrete block wall in accordance with the alignment, lines and grades shown on the drawings by Liu & Associates, Inc. 2. SITE CONDITIONS Contractor shall visit site and familiarize himself with site conditions, and shall verify existing grades, dimensions and elevations in the field. Contractor shall report any discrepancy from the design drawings to Engineer (Liu & Associates, Inc,) before proceeding with wall construction, Contractor shall exercise extreme care not to damage any underground utilities, existing structures, driveway, house, landscape, etc, Damage to the above shall be repaired and restored to their original girial condifions or better at Contractor's expense, 1 MATERIAL 3-1 precast -Concrete Blocks for block wall shall be of Keystone Standard blocks. They shall be dry cast, concrete blocks, in accordance with WSDOT 6-13.3(4), Items 3 and 4, with a min. 28 -day compressive strength of 4,000 psi. Water absorption of the blocks shall not exceed 8% and shall not exceed I% above the water absorption content of the lot of blocks produced and successfully tested for the freeze -thaw test specified in WSDOT Specifications 6-13.3(4), Item 4, Certificates of compressive strength and water absorption content tests of each lot of precast concrete blocks shall be submitted to Engineer (Liu & Associates, Inc,) for approval at least two weeks before start of wall construction, Finish and appearance of precast concrete blocks shall be in accordance with ASTrV1 Standards 01372. Exposed faces shall be free of chips, cracks or other imperfections. The color of blocks shall be concrete. gray. 3.2 Crushed Rock Leveling Base and Dminngg Blanket inch crushed rock,- shall consist of clean, durable, frae-draining, 718- 3.3 Non -Woven Filter Fabric Liner shall be 140NS by Mirafi Ind, or approved equal. 3.4 Str �icturz��IFIII for block wall backfill shall be clean granular soil free of organics, debris, and other deleterious substances and with particles no larger than 3 inches. 3.vP Wall Drain Line anti�Spreader Pine shall be of 6 -inch diameter, rigid, perforated, P ' 11 ' - W t Jgl watertight joints and wrapped in a non -woven filter fabric sock, 16 Wall Drain Line shall be of 4 -inch diameter, rigid, unperforated, PVC pipes. 17 Geogrid Mesh shall be as specified on the drawings or approved equal; 3.8 aRL!ftader Pipe shall be of A35, Schedule 80, galvanized, steel pipes d nto d required embedment with a jackhammer. 19 9 -bolts and nuts shall be galvanized for long-term' corrosion protection. 4. TEMPORARY/PERMANENT EROSION MITIGATION 71171 - 4,1 Protect and maintain vegetation outside of construction area, Install a silt fence along the downhill 8; e of construction area. Protect exposed areas of frequent. construction traffic with a minimum 6 -Inch layer of 2 -to -4 -inch rock spall, as required. Cover temporary spoil soil stockpile with plastic tarp securely weighted down with sand bags. 4,2 Disturbed areas devoid of vegetation cover shall be re -seeded, re -vegetated and landscaped as soon as possible for erosion protection. Seed mixture shall consist of 40% Kentucky Bluegrass, 30"/0 Creeping Red Fescue and 30% Perennial Rye. Seeded area shall be covered with clear plastic sheets until vegetation is fully established. GENERAL NOTES - CONCRETE BLOCK WALL, LIU & ASSOCIATES, INC. STUART RESIDENCE 1109 - 12TH AVENUE NORTH Geotechnical Engineering - Engineering Geology, Earth Science EDMONDS, WASHINGTON JOB NO, 17-097 1 DATE 9I18/2011 I P]FirE C60KTit_We_rl QPM (7L_ATr__S) 5. INSTALLATION 5.1 Stones of failed rockery shall be left in place wherever possible. Voids between stones shall be filled with 718 -inch crushed rock and densified to a non -yielding state with a concrete vibrator, 5.2 Contactor shall be responsible for cut bank stability. Keyway trench for block wall shall be excavated down to firm, undisturbed, native soil capable of rendering an allowable bearing pressure of 3,000 psf, Over -excavation to remove loose/weak soils shall be backfilled with compacted structural fill- Exposed soil at bottom of keyway trench shall -be compacted to a non -yielding state with a vibratory compactor prior to laying the crushed rock base course, 6.3 Bottom of keyway trench and wall drain line shall have sufficient slope (0.5% minimum) to direct water into the drain line and to generate flow by gravity. The wall drain line shall be tightlined to discharge into the spread pipe system. 5A Concrete blocks shall be fightly stacked with the rows of blocks inter -connected with Teflon pins, The cores of blocks shall be filled with 71a -in crushed rock and tamped to an unyielding state, 5-5 Structural fill, crushed rock base and vertical drainage blanket shall be placed in lifts no more than 10 inches in loose state, With each lift compacted to at least 92% of the maximum dry density determined by ASTM D1557 (Modified Proctor method), 5.6 Each layer of geogrid mesh shall be laid on level ground, anchored between rows of blocks with Teflon pins, stretched tight, and staked down, prior to placing the next lift of structural fill. Overlaps for geogrid mesh shall be at least 12 inches in the direction of wall alignment, and shall not be allowed in the direction perpendicular to wall alignment 5.7 Disturbed ground shall be seeded and vegetated as soon as possible, and shall be covered with clear Plastic sheets as required for erosion protection, 5.8 Construction of concrete block wall shall be inspected by a geotechnical engineer, Placement and in- situ density tests of structural fill shall be monitored and tested by a geotechnical engineering technician. Inspection fees shall be paid for by the Owner, but Contractor shall provide timely notice to inspe--bon agency for required construction inspection and testing, 5.9 Contractor shall remove debris and clean up site after completion ofwork. 6. INDEMNIFICATION 6.1 Contractor shall be solely responsible for construction safety and histher methods, techniques, sequences or procedures used for the constructon, and shall take necessary measure to maintain stability of cut banks during construction to prevent bodily injury or property damages, 6.2 Contractor shall indemnify and save harmless the Ohvner and Engineer from cost and liability for injury or death to persons and from damage to property Contractor, his agents, employees or subcontractors, Geotel,hnliial Ergif,.eeding , Engineering Geoiogy � Earth sciw.C6 GENERAL NOTES - CONCRETE BLOCK WALL STUART RESIDENCE 1109 - 12TH AVENUE NORTH EDMUNDS. WASHINGTON