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REEL
RECEIVED � .
NOV 2 0 2_CIFI_C_TESTIN LABORATORIES MA:9. , DCD
426 W. CEDAR STI Since IM
Sestge•90"•Tscioma•Penf ass•PorflaW•One tab•One CmauNant•One SoMlan
March 3. 1997 Short Subdivision .__.meals?
Cartificate No.97014125 _
MS.BECKY BHRWCH
5224 BrassBeld Drive fyAec o► o. , ;U,Mty Dasat>t»k
Olympia,WA "051
Regarding Geooechnial Evaluation of Slope Stability. Lot 24, Harms Ridge, Mason County,
WadIkom
Dar Ms. EbdW—
We haw earned out the!fold adzes necessary to complete the abovaelbreooed gecteduial evalusticn.
The following letter retort will convey to you our findings and opniahs.
SITE DESCRIMON
The property under&we== is situated in the northwest sector of a development ksorra as Ilanamn
Ridge,wbidr is itseM'situsted off (to dw west of)Ffighway 101 at a point several miles Bosh of the town
of Hoodspat (actually, just beyond M kpost 322). . The Humana Ridge develgmv t does out have
ficarge into the higinray.but a accessed by way of a private rood; a is sit000d well beds lives, and
several hundred fast above, the highway, more or less on top of the ridge, and has views over the Hood
Canal to the seat,and parts of the Olympic mountain range to the north and vast. The total development
parcel is cries-crossed by slopes and gullies, and amaen a number of ooapied bouncer of raoeot
cousbuctioo. The particular paooel which b the subject of this spat uk m noted above,n the naAhwat
of the development,and totab about 4.7 acres. R is mughly trapezoidal in abspe and is bounded an the
aset by a deep pally,dqM to the NNE The pared itself dopes generally to the a"and oast,and has
been legged(see phatogrsphd,attacbed). Anna to the south.coot,and west have also been logged;to the
north t a bounded by stataotrned focal. A number of old lcAM roads provide my waling mom to
most of the development.
PROJECT DESCRIMON
S is our uodwstading thet t is proposed to short plat the testing single 4.7-axe pared into two building
tots, roughly trisogolar in share (see suarhad site plan). Ma purpose of this Andy is to detwmiae the
feasibility of siting smgie fkmmly residences an the two proposed W.
FIELD INVESTIGATION elk OTHER RESEARCH
On Thursday, January 30, 1997,the writer traveled to the site and carried an a visual araninsdori of the
two proposed lots. A walling rocmosissance was completed, and photographs (some of wbfch an
attached to this report) were taken. A number of ptevious"xcavated test pits iron discovered and
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MS.WXY EHRIJM
Certificate No.9701-4125
March 3, 1997
Page 2
exanmed. In addition, a previous sods report prepared by this company am the Hamm a Ridge
development(PT7, report to Kooley Caortrnaim, dated Jima 16. 1995)vats reviewed,as was geological
baekwo nd nfanowbon on the general ares,provided by the Geology Department of the sate Department
of Natural Resources in Olympia.
FINDINGS
The arm of the proposed plat appears to be stable and wdl drained. The parcel is,as noted is a previous
sedim,situated on a ridge to the west of Highway 101,elevation ofthe lowest(ad)and is about 500 feet,
while to the wet it rises to a high of 600 Rat(amtbwast comer). Beth the purposed lab slope faddy
uniformly to the norlheM at about 209k but Lot 2 doper steeply along its east side wham it contain the
side slope ofthe sully mentioned above. The at property lire of la 2 more or lob Mom the bottom of
the gully(sex site plan). 76e gaily side slope a also quite miPonn,but relatively steep at about 167%(or
•600). The upper.more 1rooMr sopng sections of both lots Lave boo cleared,but the side slope of the
Sully is covered wd h dam brash and hmnmrrc trey(ere photographs).
All ha sub to the east ofthe development the boar slopes oftbe WE particularly in eras where the ndWW
slope has base undercut by the road(F6g6wrgr 101),exhibit numerous active slide tress,and an maked
by smft drams and seepage dwduqM down the slope, the subject pmpwty is dry, and in $ct the
whole development ams appears to be siNabd on tims•dmioios sods which ileum a mouth on as upper
ridge. We farad no imdiosticm of waft either on die side slopes or in the bottom of the gully. The mantle
soils across the ridge, mwsled in the ter pit ws located on the parcel, and is omnmcer wed ate and
sursoa exposures (old logging roads and doidder trail, we photographs), are I bl, in nature. The
surface sa's esaadiig to a depth of about 1 M feet are loose, reddish brawn sandy shah to sity made,
containing small gravel. Below this the soil exposed in the oat pit urea a gmysh-1 mwa,meadows to cows:,
dame sandy travel. The a sommus seepages and spriege above do highway indicate that this gravel is
rnderb n at depth by much mum slowly permeable sediments. Hamm,no ndieadom of seepage;was
found anywhere on the pared under ditcmmo. Because of the permeable nature of the surface and near.
surface soils runoff w probably slow•,no ndicadmns of erasion were evident.
Remaining vegetation consists of valid rhododmdrm various berry specie, salad,and gran iotsmugl d
with unidentified wads.
CONCLUSIONS elk RECOMMENDATIONS
1. General Cammanb
In our GPWN the pmpand plat is quite Raerble;the two proposed lots will each oaten adequate space in
Much to cmdmret a:ogle$wily residence an relatively Sently staining areas while mantammi;adequate
setbacks fiom any steep slopes. In feet this s not really an owe with regard to the nos westerly of the
two proposed dab (Loot 1) done it does not coutda any really deeply doping area. As do atltcred
topographical map of than pared slows, la 1 slopes muse or ban unifbrmly to sirs NW 7% tastes
section of Lot 2, an the other brad, camas the step wasim aide dope of the oddly,tam an adequate
setback will be required for any proposed conaroction(or ground dsahrbdmos in goow4 an this lot. The
trAtituicron 42"1
4—R8—
It ddd
OAst,1 Holly Dwefopnvcwt
1
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MS.BECKY EHRLICH
Certificate No.9701.4125
March 3, 1997
Pap 3
recanunaidations of the folbwing sections must therefore be strictly ihnplenented during site preparation
and all pro-construction excavation or grading work.
2. Buffer A Setback
In the case of proposed lot 2, a buflar seine which should be left oampktoly undisturbed should be
established to include the entire area extruding west fionh the rot property We (bottom of gully)to the I
west Of die golly sideslope. This Should be Bagged and shoem on the plan of this let;the crest is sharply
defined and Amid be easily established by inspection. The monhmanded bu for a down un the
accompanying site plan. Behind this a feeler 25-foot setback should be observed for a0 construction(see
Eke plan).
Because both lots slope across the possible building area same cutting and/or filling will be repared to
Flo-o aaawimdm situ. a the case of footi 1p;ad an fill a setback of ftva(5)feet,horizontal duti moo,
read be maintained between the outside edp of the footing web and the tap of**outalope of the pad A
sim err sdbacr do ild be observed for fboti es set in die base of a as (see susched figures). Fill
placement and compaction will be discussed in a later section.
3. Soils Chmacha istica
The soils present at the site are Witable for the ems wdm of single bmily nedde cos on shallow
fouo&bm(i.e., cootimous or spread ),provided that the tooting,ate act an em&ahubed,Hive
soils from 141ch all aganic mstmids and bone soil or debris has beer►mnoved,or on aaopacted fill. 7%
Me soils may be used as fig under structures and pavements or walks.as Img as troy an fFee of organics
and debris of any kind.
If retaining structures are to be utilized (eg., in the construction of a daylight basement)the fbklowiig
values should be used in a basis fbr design:
Lateral Barth Pressure Qr B.P.),active 35 ib&W
Lateral Forth Pressure(F.B.P.),at fast 55 Ibslft'
Codficimt of Sliding Ffwborh,Ke OA
The sae soils are Owly to be erodible when in der dismrbod condition,*wePoro the r000amandi tioos of do
lblbwiog$action mot be strictly observed during age preparation,and aft work avolving earth onovahout.
4. Erosion Central
All Permaout ink Acss emst be laid bast at an inclination of not more than IH:IV,and protected at We
owing Possible time by the estab idwas t of vepg ing Vegetation shoaled consist of lawnmateaanos
indigenous species wherever possible:des"seed p maaton the slopes should be protected by coverag
them wish Properly sensed dear plastic sheet'shg. If gro nd-ooverag shrubs such in oeegon grips are
planted straw ankh may be substituted fir the plastic sheeting. Slopes steeper than this(up to HOV)
must be protected by the hue of rockeries. Now that rookeries off I- than filar(4) fast in 6e' Ile easy
fihor vision
4 .9
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Wale ant
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frowns•Caraann.SrMain
MS.BECKY RUJIMICH
cort;licaoe IVo.9701-4M
Mamh 3, 1997
Page 4
require a separate budding Permit.and be subject to certain building codes. A typical rockmy canes-section
is attached.
Ann downslope from construction activity should be protected by do placement of A chase fjdie work
is bring done daring the miry season. Similarly, if the we&a being done during rainy weather runoff
must be prevented firm entering the disturbed area by the placement of diversion drains or other device
such w bales of straw,or sand lisp.
5. Full Placement
AN structural fill(.e.that under buii%p or roadways)mad be coopatxad,and should not contain easree
materials each as Imp cobbles. Fill which will support fbotisgs anus be compacted to at best 95%of
optinwm dry density as per AS7M D-1557;it should be placed in loose lifts ornat ninro stem 12 finches it
thidmses, and each lift should be tested for compaction bAn the nest is placed. Fill under waft and
driveways mast be compacted In mat less than 90%of op" dry density. Outzlopea composed of fig
must not exceed 2HA V unless the soil is either reinflorced by the use of a geogrid or supported by a
retaining structure.
Fill may curly be placed an aarflsow which have firs ben thoroughly Palm d. This nhsane that an
vagetsbas and organic material most be removed; if fill is placed on a surf►ce which elopes at an
inciimaN of morn than 5%der surf me must first be keyed as shown in the attached figure. !hider no
circumstances shag structural till be placed on a slope greater than 15%.
6. Landslide Hazard
Cavan the flmerh mom roils which domlsaw acron the area,the absence of any significaum erasion feature;
and/or tips of groundwater seepages,and the mostly gentle and Babb slopea,we do not believe this parcel
to be especially at risk ficm landslide due to natural om ms. Provided that the moaanmddicm of the
previous section on woman control are strictly implemented we believe the risk of Irhdslide at this site to be
minimal.
7. Drainage
The site soils am of suitable fbr the disposal of stare water runoff by the utilization of
reteotimAnfikraticn devices. The design of such f1scalities floes beyond the scope of this study. Storm
water r toff must be controlled however,and should not be allowed to discharge onto unprotected ground
surf6ow.and undo no ch cunstancea should k be directed auto the gully or ks sidestope.
S. Stmunary
In summary,it ls our qm m die,provided all of the Moom mamdstios of the previous mob ms are WmdY
implemented,throe a no geotecnieal reason why der Proposed Plat, ON we understand k, ahoml jaot be
aibwedtoproceed. fillort w.nom -za�J
Appri
DwNop mam
ncF1_ Iti1FR3t' b
PicMc TislN1B Labott><afss
.cona�np.arr.„arrr
MS.BECKY EHRLICH
Certificate No. 9701-4125
March 3. 1997
Page 5
LIMITATIONS
Thin rgimt has been prepared m accordance with Seoeeapp accepted mommenag p+gagphai and prectiaas.
We make no wamoty,edher eapraased or zWhed. The opiniens expressed we based on the resorts dour
urvneigaticns, and observable oondkioos at the sibs. They shoM not be applied to atlrer, entrmmdiog
properties. If conditions are encountered which appear to diBter Does than described o this report we
should be i mw&atay notiiled so that va may review the sitwtion.
This report is for the mibrmetwo of our dients.Gerald and Becky Ebruch,cell, >LY and
tranaoitml to any third Party by any mesas. coo" hr &r a wahorrt the written anthonatioo of
Pactfic Tatting Laboratories is prohibited•
We would like to thank you fen having selected our omVwY to provide yen wlh albeerirg aervioes.
Plase contact the writer at(206)589-1804 should you have questions coocuft any of the 000taMs of
this letter.
Reviewed by. Kurt W.Groesdr,P.B.,Director,Camtrudian Services
Sincerely
Alastair Laoisde /T
Senior Geotedeical Soma,construction Services
s�he�ubdiyiriort
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25• Setback
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Shoving Slopes
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T p° K Scale: 1' a 1001
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