HomeMy WebLinkAbout947400033 Geotech Assessment (2005)s. A
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.:... - Environmen#al sneering • Geo#edznkal Engineering • Vv'etland Consulting
26 Tune 2005
Project No. ACLDS-06fi057
Aquacultwre Systems, tree. Y ',
P.0.13ox 417 ~ `~
Sequim, Washington 98382
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Attention: Mr. Steve Falter ~ € ~:-' ~
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Stebjec~t: Retaining wall Assessment j
Lot 33, Discovery ~1+ Village ~ ,
Tax Parcel # 447400033
Jefferson CcH~nty, Washington
Mr. Tager,
At your regt~ ALKAI Cortsttltants, LLC (ALICAI} has performed a geotechnical assessme~rt of tim constructed
retaining wall at the subject lat. ALKAI understamis that Ibis ash is being required for building permit
approval on the subject lot. .
The retainiisg watt ~ located an the eastern portiost of the lot where it traverses the lu'llslope. The wall is part of a cut
and fill on the lot to develop a level bwlding an~ea. A schematic cress section of the wall is shpwst in Figwe 1. The
wall serves ~ retain fill on the downhill portion of the devekped area. A'[,KAI understands that the fill is a maximum
of 4 feet thick and extends approoxim~tety 20 fi:et back behind the watt. The wall runs nortTt to south and measures
approxis~aately 4 feet high alai l 00 feet bag. The wal l cxinsists of two rows of ecology blocks mat~tefaetured by Fred
dill Materials. Wiffi the exception of tapering bbdrs ax each cad, each block measures 6 feet wide by 2 feat high by 2
feet thick and weighs 4,400 pads. The wait is battered back itnho the hillside at apQroBCimately I :6 {horino-ntal to
vertical} ratio. The wall has beesz barckfiilled to a relatively flat level to the full height of the wall. The wall aatd ~a .
baakfilI sbpe ~radualty to the north.
ALICAI understands that the design of the wall adopted engineering design recommerulations prepared by Kraxaa &
Associates fpn sinu7ar wails within the Discovery Bay Vijlsge Developmea#, ALKAt u~ds t1nR the wall was
keyed into the very dense native sods. These subgrade sails were inspected by an AX.KAi representative on i l
October 2004 and wen found tD be acceptable as subgrade for the wall. (sec attached Field Report No. 1) ALKAI
understands that drainage was installed ax the bay of ~ walls to pr+eveat the buildup of groundwater behind the
walls. The draie~age system consisted of approximately 0.5 feet of pea gravel placed at the bottom of the wall, with a
geotextik fabric that was placed fiat over the pea gravel. Then, 4-etch wrapped ADS drain pipe was placed on the
gewtextik and ffi~ another sheet of the geotextile fabric was place above the pipe. An additional I feet of pea grave!
was placed above the pipe. The remaining barl~ll behind the wall consisted of native granular soils, o~nsisting of
well-graded gtronre! with sr'h and sand $ackfeA was cooed construction equipment trio from a D-7 doper. The
drain p#pa is sloped to discharge ~ the north end of the wall.
The cxmstructed retaining well and associaoed baclefill was inspected by an ALKAI gecatechnical engineer on 241une
2005. Observatioats indicate that the wall was adequately designed and constructed m function as a 4 foot high
retaining structure, 13acki3Il soils were probed and wean determined to be dense in the area of the proposed structure
near the south end of~dte wail. Elackfill soils were wed to be loose m medium dense behind the naardt end of
the wall.
9b6S PROVOST ROdwNW, Stti17C X048 • SH.VERDAi,$, wASHt1~MGrOTi 98383 P:ektNlc: (360) 6'13~24lJ Fw7r: (360) 613-2AOt
< No. AcLOS-~cosr
R Wall +t, i ~t 33 f)lsoavay Bay YAhge
25iata:2Q03
Pag`N°''-
ALKAI understands that Aquacuhure System inc. intends to construct s siagie family residence oa tLc pad and that
the east end of the residence will be located approximately ! 0 from the t~ of the a~ retaining wall, as
shoriu in I?i~ttre 1. Based oa ALXAI's understanding of the construceed wall and observations made during anti aim
G~struction, tltc proposed residence locatiaa appears to be feasibh: using a shaliaw foundatitm system adjacent b
this retaining wail, provided iltat She recommendations providedui our ~ report {Pretim~arY Geolagiatl
Assesuncnt, Discovery Bsy Developnieut, Discovery Bay Village, ,lefkrson Courtly, Wa~itington, dated 13
September 20Q4) are implemented, snecifical{j+ pertaining t4 minimum footing. depth {IS inches} sect discharge of
drainag4 systems (away from slopes and disturbed soils).
Should you have any questions or cottce~rns, wlucdt Sava trot been snddressed, or if we tmry be of additional assistance,
please call our ol=!ice at {3bQ) 6I3-24Q7.
Since:elY:
li
Jay C. Davenport, P.E.
Senior Cmotechtdcal Eag
A~
Figure l
Field Report 1
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At.KAI Consultants. LLC 9465 • Provost goad NW. ScSte 204 B ~ Sllverdpt~ Wasl~ir~gfion 98383 • :_."'--
Ph.: (360) 613-Z4p7 • feu: {360) 613-2408
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t~~•~~l CQNSUL~'ANTS, LLC.
~- ><n~errg • ceo«at »t~ear>~g • vv~,a ~~
F1~LD 12Lt~RT
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DATE:10/l 1/i34 CONTRACTOR ems, LLC.
PROJECT #ACL 0+#-Glfl2 LOCATiUN: Disco Ba , OVA
PROJECT: Dino Ba JURISDICTION: rsfferson , WA
The undersigned arrived at 12:00 p.m. to monibr sde vxork Ecology bock retainin+~ walls were being cgnstructed on bts 33,
34, and 35. Observed subyrade for 3 fwt of the 5 bock waNs. The tdning two wags wF~ be observed at 8 titer date. The
wad observed this date were the 75 loot, 80 foot, and 150 foot long retying wad. Subgrade probed firm and unyieic~ng
witf t approxitnataly 3 t4 4 inches peee~atign vrith 112 Inch T-prob. One iocaiit~ area of the 80 bat r+s~ining wall pry
approximately 1.5 feet near the cut for the drain pipe. This area does not appear to pose a significant threat to the waH due to
the relatively short height of the waq. The waq iS proposed to be t m 2 bkxks high wkh drain rode and pipe behind the waq in
this step.
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Sbtf eeotog;st; Senior t3•obgieC .~
9+65 Arouost Road NW. Suite a04B • riveraate, Washington 9$383 + (360) b13-24x7 • Fax: (360} 613-2408