HomeMy WebLinkAboutBLD2007-00493 - BLD Engineering / Geo-tech Reports - 7/11/2007 s Q. r
E N 6 I N E f N I N G\ I N [
309 WASHINGTON STREET NE • OLYMPIA WA 98501 • TEL:360 352-2477• FAX: 360 352-0179
www.vectorengineeringinc.com
RECEIVED
July 9,2007 JUL 1 1 2C01
Mr.Robert D.Fink,AICP MCCD - PLANNING
Mason County—Department of Community Development
Mason County Bldg 1
P.O.Box 279
Shelton,WA 98584
Subject: Geotechnical Report Request for Additional Information
Permit#:BLD 2007-00493
Parcel No. 12207-75-90072
Applicant:Joshua Ferreira VECTOR ENGINEERING, I N C,
Planner: K.McAboy
VEI#: 7054-009
The geotechnical report prepared by MET (Morta Engineering and Testing), P.O. Box 250,
Ocean Shores, WA 98569-0250 for a proposed residence with septic system at 230 E. Baker
Court, Belfair, WA 98528 was received and reviewed by Vector Engineering, Inc. The
Department of Community Development requested the review for the purpose assisting the
Department in determining the amount of potential for landslide activity and the proposed
development would not cause significant adverse impacts or there is adequate geological
information available on the area to determine the impacts of the proposed development and
appropriate mitigating measures. The Department of Community Development reviews all
development applications to determine if they are likely to be in or near a landslide hazard
area per Mason County Resource Ordinance (MCRO), Geologically Hazardous Areas,
Landslide Hazard Areas 17.01.100, Seismic Hazard Areas 17.01.102, and Erosion Hazard
Areas 17.01.104 approved December 27,2006.
The geotechnical report states the proposed residence will be within the south of the Hood
Canal along Alderbrook Road. A site plan was provided with the report and a description of
the size and location of the proposed drainfield and residence was provided.
Based upon preliminary review of the report, it is requested the following items are requested
or be clarified before the review of the report is complete.
Additional Information Requested
1. The report includes a discussion of geologic conditions in the general vicinity. No
discussion of upslope geomorphology and location of upland waterbodies and
wetlands was included as required by MCRO 17.01.100 E.5(1). A revised discussion
is requested.
Page 1 of 3
X:\7000 Files\7054 Mason County Geotech Reviews\7054-009 Mason Co(Ferreira)\Admin\Transmittal Letters\Geotechnical Report
BLD 2007-00493 Review Request.doc
i
�' o, r Invoice
f N 6 1 N f f R I N G \N (
309 WASHINGTON STREET NE
OLYMPIA WA 98501 Number: 7-901
TEL:360 352-2477 FAX 360 352-0179 Date: 9/10/2007
www.vectorengineeringinc.com Due Date: 10/10/2007
BILL TO: Job 7054-009 Mason_Co(Ferreira)
Mason County I
Dept of Community Development
PO Box 279
Shelton WA 98584 PO# BLD 2007-00493
SHIP TO: Project Manager: Russell
SERVICED ITEM DESCRIPTION QUANTITY RATE AMOUNT
6/27/2007 50 Proj Ad... Project Administrator 0.5 50.00 25.00
9/5/2007 31 Eng 3 Engineer III 14 80.00 1,120.00
9/7/2007 51 Admin ... Administrative Assistant 1 40.00 40.00
i
I
Terms: Payment due 30 days from the invoice date. 1%discount if payment Total $1,185.00
received 15 days from date of invoice.
Payments Applied $0.00
Credit Cards: We are now accepting MasterCard and Visa. Balance Due $1,185.00
Please call to make payment using your card.
,' Reddish bravo slay loam,I-my silt(SM) Typical IaaY e.ctiort
Head C.ftY Allowable wd bearing cap"1000 psf
2' 6 to 10%moisture dnrhe C Salb ,rambler
W 7 Preserve all trees and vegetation
230 E.Baker CL P on tM 501.60%slope
4
v - 1
Light gray very dense glacial fill(G W W) - Q
N 5 -L, with an allowable sod bearing capacity of - _-
�- 3000 to 4000 pall and a 5 to 7%moisture r-0 b 5�Slope
�1^fI mntenl
B Bottom of am footings steep •" •�
reel on the NipI31UtB�
dense prey glacial of for
NI'1rllN M-p B' \ anon, t of the
b
Nob:This icaw r span fie
raped out
on
N r--- — -\ ps dung the just
PRIOR t for the first
concrete
and also jtrat PRIOR to thte first wrtcreb
par to verify that the foundation s bail b
"\ constructed on UNDISTURBED glacial
till material and prepare onside report and
Old kwkv �{� :� verify that the 20•setback is toet as
Yid lo.d ,sue - _ indicated on the drariag.
Urmined se.aanel creek in this direction
GEOLOGIC MAP OF 7}E 81TE `� `. (11a from do propo..d residence)
� Relatively level In this area ash,therefore,
/ does not present itself as a landslide hazard.
hhi.tenody leerlitp�o.e., % gz` t
ar old ibesmdb50bBO%slope. NoeNdexeolsa erosion, 9� a
cE grand rr8eures,a other s.his --
`�q3 of instabifitIr n the area of the K
3, seasonal creek.
500'Datum
Elevation
`� 3'x 3'1
10'infiaration
Pal811 bu...md�.yw.�w.` Iren,filed with 1 to 3' f \
an the SOb III fill \�r dia.drain rock and Geed ts.ImIh 759 220700n
<
4Bd '4W w/a geote4le fitter fabnc.EW& ;ENv 4g0' min.20' n Rn Sd
' 475' pay. r -
Flew ,;495 Elev. \ d
N�
/ Sop Log Basting 25 yr
old cedar bee
_ Preserve ash trees and vegetation 2-cw
in cis 50 buffer zone - �� py.rld.rtC. i
dowdilard --50'setbedksom Soil Log a..erttwt
i YaD. ` embankmerrt edge
A per MCRO 17-01.100 Proposed
--- 5O'seflasdk iron ----� 1�� D.6(a) single story
rambler
vp/L Humid 1>ef kN3tO
...Acre' U7 ,fr o,.1W D.6(.) � i • ... a
Jf.N P dyp'+ 3; a y� 4 e Q
yrk DF WAsyi + qE S ifp
R� hC 7 Proposed Preserwe all trees and vegetatim R,' ' Q? LL m
�r 0 Septic drainfield in 1hs50'buffer zone
.r� LeMlide.a and
��Rg4S[tn"-��k%� LBardarfes__J 9v � �Q
E%PWEB 30758
`O n aFt I
Casatachnkal ErngirroiI Report per the Masan County Resource Ortfinance
3@9don 17 01.100E updated on DocartMv 27,IOOB
(1)General Geologic Conditions and Upland Geomorphology.The entire (8)Racormmrdatlon for the preparation of a detailed claar*N and
Puget Sand mgon has undergone far major gacial adratcee and moassions grading plan which specifically Identifies vegetation to be removert
with the last cycle occurring approximately 20,000 rears ago leaving gledal till a schedule of vegetation removal and repiaribn&and the method of
and mnpactsd coarse sand deposits as observed on the site. These glacim vegetation rammovaL The proposed building site is already in a dearnd area Q
were over 12 a mile high and,therefore,placed heavy pressures on the glacial wwth no rernoval of trees a major vegeaison required it is recormrarded that R3
tilts rand sally deposits under these glaciers the edstrig surface grasses and rods be scarified and rerrhwed from the site
The upiard gaornorptology consists of an 8 to 10 deep incised se teoral prior to construction If construction ocares during the miry season from
m .4
unnaed creek that flows from south to toward the hood Carol. The upland November through May.arry bare grand will need to be covered with 8 mil 11
area is relatively level with no evidence of previous slide activity such as ground viaqueen to prevent soil erosion. rn
fissures or hummocky seas. Dense forest vegetaton in the upland region
increases slope stability due to their extensive rod systerns and canopy cover (g p�for the preparation of a detailed ternporstry
which protects the soils from direct rainfat and helps to deweter the gourd —ion control plan which k1 ndfles thhe spacMc mttlgatng namasures a
Tm*the process of evapobarupirmon tmig h their rods and tee limbs. to be knpNrterled during u:(Ife1lUCtla1 to protect the slope from aroslor4
Thane was no indications of wetlands,surface or subsurface seeps or stardkhg landslides and harmful construction netlods.
water except for the seasonal"earned creek just mentioned an to the relatively Rio to mrstrlxAorh activities on the site,geotextile siltation fextng shall be
is
flat upland teran and the absence of%et sal conditions,the likelihood of any placed on the downhill side of the building site to prevent sell erosion of the
slide atrvity is essentially normastent ernbaknhal. In addition,gootaxtle sttabon fencing shall be placed on both
The specific soil type is a reddish brown sty loam,loertry sit ISM)mth an %des of the building pad It is remrmended that inttial mnstnxctoon take
albwabie soil bearing capacity of 1000 pet and a 8 to 10%noistre content. place during the drier times of the year from mad May to mild October and that
Below 2-12w thee is a light gray very dense glacial bN(GVVV SNf)with an alloy de the residence be weathered in by the tegnraN of November if ran is
sail basing capacity of 3000 to 4000 psf and a 5 to 7%moisture content expected all bare grand is to be protected with 8 mil vi squeen to mrrrttze
scil erosion of the building site and the resulting water runoff to be directed
Site Plan of it*Inporb"drvebpnent and geologic Moires. AWAY FROM THE SLOPE
The site pan on sheet 1 of 4 sFhows the location of the proposed%ogle story N
residence along with to proposed driveway to the 2-cir garage. (10)An analysis of both on sloe and off-site Impacts of the proposeddevelo dS5
(3)A log of exploratory test hole.On sheet 1 d 4 the pest hale bcatw and there vp be r Since the building site is mashy Ina cheered arse is appr,
the resit sit are thdiceted. these will be 25U al ay from
impact.Also,the building in eta itself rs eppwd-
n9 b9 rretety 200 to 250 entry from the nearest neighbor in the area and,tlherekxa,
(4)Area d proposed development,hazard boundaries,buffers and such things as construction noise,vibration,trea will be etc will have minimal
setback delineated on■geologic meµ Retenng to the geologic map on impact toa the neighbors. Needy re the braes will be preserved i remseptic eel
this geotechnical engrheerirg report except for Bose that are in the septic �.
sheet 1 of 4,a 110 buffer is from the unnamed creek located on the
Pno'^otd drainfield area as indicated on sheet 1 of 4. a
east and of Oho properly to the proposed building site.Also,a 20 ssYbedc will
provide adequate protection from Niles as indicated on the geologic map. The (11)3pect iratbre of anal development conditions such am,vegetattva
proposed location of the dranfeld is located r a reiatAey level area and is mumgerrera,drainage,erosion control,and buffer wldtn.AN surface $$$
also 1W away from the well as required by tie Mason County Health Dept water runoff from the rod shall be directed into a 3 wide by 3 deep by 10 i
long infiltration trench as indicated on sheet 1 of 4. The mfiltaton trench shall
(5)A minimum of one cross sectIm at a scale which adequately depkxs be at least 30 from the edge of the embarkment and whit allow the water to
the subsurface profile,and which incorporates tle details of proposed percolate back into the gourd and evertualy recharge the grand water AN r o R-
grade changes.Adeailed cross section is shown on sheet/of 4 that bee areas after mretnxmon shall be vegetated or teed to prevent sal erosion
indicates that the top two and a half leaf consist of a reddish brown silty loam, with plants that are indigenes to to area A 110 buffer shall be maintained q
loarny%t(SM)with an allowable basing capacity of 1000 pst and a 8 to 100/6 between the unnerred seasonal creek to the east and the proposed residence. yyy Z
moisture talent fodamed by a 8 to 7 foot layer of light gay very dense glacial
till(GW_SM)with an allowable sal bearing capacity of 3000 to 4000 psf in rts (12)Recammerdatlors for the preparation of structural rtdtlgatlorh a
UNDISTURBED state and a 5 to 7%khsihr moisture content details of other proposed mhtgatlon.The construction of the infitratm
fence referred to in(11)above shall be fired with geotextile fitter fabric to
(5)Description and results of slope stability analyses for both the static prevent fha 1 to Y diameter drain rock from becoming filled with sit the would
and"Ismk loading conditions and should examine worst cam failures. affect percolation of the surface water runoff bade into the grand water
The arm"A should Include the Slmpltled Blshop's Method of Circles.
As irdiceed or,engineering sheet 3 of 4 a detailed slope stability has been (13)A site map drawn to rasa shoving the property bourdades,scab,
perfor ed for both the static and dynamic cases using a modified form of the north arrow,and the location and nature of existing and proposed
Simplified Biskop's Method of Circles.The reciting facer of safety for the development on the ate.Refer to sheet 1 of 4 for the site plan. Note that
static case was 2.14 which was Beale than 1.5 and,therefore,the static slope the site plan and geologic map with the elevabon mrfour a and other geaiata
stability fates of safety was considered satisfactory. Similarly,for the dynamic has been included on the same plan.
or sasmlo the resulting factor of safety for a quas-static aalym coefficient of s
0.15 was corhputed to be 1.58. Since this is greater ten 1.10.the factor of S N
safety of 1.58 was considered satisfactory.
(7)tiestrichons on placarrernt of drainage features,septic drain fields and
compacted tills and fooerge,and buffer and saDecks front IandMide
bei areas.As indicated on sheet 1 of 4,the mfdtaton trench will need to
be lasted at least W beck from the edge of the erhbenivne t to erwe gg y
over ail stability of the slope.The septic drakhfield is located on a relatively level r7
area as indicated near ate base of to dope and shall also be located at least
100 away from the well. W
Footings shell be constructed on UNDISTURBED glacial till. This engineer shall
be called out to the job site during the excavation for the footings anq again,just
pia to the footing pax to ensure that the footings are resting on UNDISTURBED
native glacial bill.
Slope Stability Calculations (at Cross-section A-A,)
20'
Rotational Failure
Plane LNot io wale kwC
31 deg(60%slope)
1. Compute factor of safety(FS)against slipping-Static Case(Ref. "Stability Charts for Uniform Slopes"by
Radoslaw L. Michalowski, FASCE) - Stability Charts have been included with this slope stability analysis.
From Figure 3"Stability charts for uniform slopes"the following parameters are known for native glacial
till materials:
c(cohesion)=250 psf,gamma(insitu unit density)= 142 pcf, H(height of slope)=30 ft,
phi(intemat friction angle)=38 deg, then
c4gamma x H x tan(phi)]=250/(142 x 30 x tan 38)=0.075
Then for a 31 deg slope from Fig. 3:
F/tan(38)=2.74 or, F=Factor of Safety= 2.14>1.6 OKAY
2. Compute factor of safety(FS)against slipping-Quasi-Static(seismic)Case(Ref. "Stability Charts for Unfform Slopes"
by Radoslaw L. Michalowski, F.ASCE) - Stability Charts have been included with this slope stability analysis.
)
From Figure 4"Stability charts for uniform slopes"the following parameters are known for native glacial
till materials: i.
c(cohesion)=250 psf, gamma(insitu unit density)= 142 pcf, H(height of slope)=30 ft,
phi(internal friction angle)=38 deg, then
c4garmia x H x tan(phi)]=250/(142 x 30 x tan 38)=0,075
Then for a 31 deg slope from Fig.4 for a quasi-static analysis coefficient of 0.1:
F/tan(38)=2.25 or F=1.76,
For a quasi-static analysis coefficient of 0.2:
F/tan(38)= 1.78 or F= 1.39
As a result, for a quasi static analysis coefficient of 0.15,the Factor of Safety, F=(1.76+1.39)/2=1.68>1.10 OKAY
Sk4w Stability Analysis for property located
at 230 E. Baker Court,M 98528 Prepared by: Mo. Er4nee►1ng a resting,PO6 250,ocean Shores,WA 98569
— Prepared for: Joshua Ferreira (360)289-0958, (800)590-0958,(360)289-9682 fax,Smrta@,AOL.com
14120-49M Ave Ct.NW --- -- _
Gig Harbor,M 98332,(253)312-4108 cell Aug 2,2007 Analyzed by: SPM Page 3 of 4-
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BolrMry Urw Ibr Prapelly lotabd at 230 E.Baker Cart PePmd by.ltf Pd�".q.W Twang)
Belfair,W498.528,(Pa,od#1220 7758 007� P.O.Bm 250,Oaan Shaer.NM ea588-=der AACRO 17.01.100 ES(13) __ _- (800)590MM,(36D)289-9642 f)c SmoAaGO morn $CMD 1.
PreMmd for Josko FMnka Mar.21,2007
1N20-/9tl1 Are CL NW0 1V 20 w
Gig HOW NM 98332,253)312-4108 ool Roy..Ay.
2�2007 ���'9PM PaP 1 of 1
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f N 6 ! N f f R I N 6`.. I N C
309 WASHINGTON STREET NE • OLYMPIA WA 98501• TEL:360 352-2477• FAX: 360 352-0179
www.vectorengineeringinc.com
RECEIVED
September 5,2007 SEP 1 1 2007
Mr.Robert D. Fink,AICP PLANNING
Mason County—Department of Community Development MCCD -
Mason County Bldg 1
P.O.Box 279
Shelton,WA 98584
TO BE KEPT IN THE
Subject: Geotechnical Report Acceptance
PARCEL FILE
""tt#:BL
Applicant:Joshua Ferreira
Planner: IC McAboy
VEI#: 7054-009
Dear Mr. Fink,
The geotechnical report dated March 21,2007, first revised geotechnical report dated August
2, 2007, and second revised geotechnical report dated August 24, 2007 prepared by MET
(Morta Engineering and Testing), P.O. Box 250, Ocean Shores, WA 98569-0250 for a
proposed residence with septic system at 230 E. Baker Court, Belfair, WA 98528 was
received and reviewed by Vector Engineering,Inc.
The first revised report and the second revised report clarifies several points in the original
report. The second revised report shows the proposed residence and drainfield to be 50 feet
away from the landslide hazard area.
1. The report includes an incomplete site plan, which identifies some of the important
development and geological features. More detail is needed as per MCRO 17.01.100
E.5(2).
• The response is adequate.
2. A geologic map of the site showing the area of the proposed development, including
the boundaries of the hazard, and associated buffers and setbacks was not provided.
MCRO 17.01.100 E.5(4).
• The second revised report includes the above referenced missing items. The
response is adequate.
3. A cross-section,which depicts the subsurface profile, was not provided as required by
MCRO 17.01.100 E.5(5).The cross-section provided depicted the surface only.
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X:\7000 Files\7054 Mason County Geotech Reviews\7054-009 Mason_Co(Ferreira)Wdmin\Transmittal Letters\Geotechnical Report
BLD 2007-00493 Review Acceptance 070905.doc
• The revised cross-section is adequate.
4. The report includes a slope stability analysis performed with static and seismic
loading conditions. The slope stability analysis was used on one type of soil, a dense
light gray glacial till having a drained shear strength value of 300 lbf/fl,a phi angle of
41.3°,and a dry unit weight of 133 IbI . The phi angle is higher than what was used
in other reports. No loading factor for the building appeared to be used. The report
also mentioned the existence of a topsoil of reddish brown silty loam, loamy silt. The
slope stability analysis used was not the recommended Bishop's Method of Circles.
The cross-section should be longer to include the areas outside the slide area. The
method used was a limit equilibrium version of"Simplified Wedge Failure on Planar
surface with Length L." page 775 figure 20.2 Civil Engineering Handbook, CRC
Press, 1995. It is recommended a new stability analysis be run and justification of the
soil properties be provided. MCRO 17.01.100 E.5(6).
• The revised slope stability analysis is adequate.
5. The report includes recommendations on restrictions on placement or proper drainage
features, septic drain fields and compacted fills and footings, including recommended
buffers and setbacks. No concentration of runoff is recommended and discharge of
runoff should be piped in a closed conduit install on the slope face and taken to an
appropriate spot beyond the toe. The septic drainfield should be located at the bottom
of the steep slope. The house in the report was recommended to be 20 feet away from
the top of the slope.The proposed house location appears to be in conflict with MCRO
17.01.100 D.6(a),which requires a 50-foot buffer of undisturbed,natural vegetation.
• The second revised report shows the infiltration trench more than 50 feet from the
top of the slope.The response is adequate.
• The second revised report shows the proposed septic drainfield in a portion of the
landslide hazard area to be 50 feet from the bottom of the slope. The response is
adequate.
• The second revised report shows the proposed house location 50 feet from the top
of the slope.The response is adequate.
6. No recommendations for a schedule for vegetation removal and replanting and for
method of vegetation removal other than careful limbing were provided and
preserving all trees and vegetation not in the drainfield area or in the proposed
driveway.MCRO 17.01.100 E.5(8).
• The response in the revised report is adequate.
7. The recommendation for a temporary erosion control plan needs to include specific
mitigating measures to be implemented during construction to protect the slope from
erosion, landslides and harmful construction methods. MCRO 17.01.100 E.5(9). The
report only mentions geotextile erosion control fencing.
• The response in the revised report is adequate.
8. The report needs to include recommendations for the preparation of structural
mitigation or details of other proposed mitigation MCRO 17.01.100 E.5(9).
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BLD 2007-00493 Review Acceptance 070905.doc
• The response in the revised report is adequate.
9. No specifications for final developmental conditions were found in the report as
required by MCRO 17.01.100 E.5(11). A summary of final developmental conditions
needs to be provided.
• The response in the revised report is adequate.
10. The report includes a site map drawn to scale showing the some of the property
boundaries, scale, north arrow, and the location and nature of existing and proposed
development. A more complete site map showing the entire property boundaries is
needed MCRO 17.01.100 E.5(13).
• The response in the revised report is showed the east boundary. The west
boundary also needs to be shown. Page 4 in the second revised report includes the
boundary lines of the property. The responses are adequate.
In the reviewer's opinion,the report and the revised report does provide sufficient information
to determine the project will not decrease slope stability at the site or on adjacent properties
and the risk for such occurrence would be minimal.
The conclusions presented in this report are based on Vector Engineering, Inc.' understanding
of the project requirements.Vector Engineering,Inc.warrants that its services were performed
with the level of care and skill ordinarily exercised by members of the same profession
currently practicing in the same locality under similar conditions. No other warranty or
representation,expressed or implied,is included or intended hereunder.
The invoice, the geo tech work order, the original geotechnical report, the first revised
geotechnical report,and the second revised geotechnical report are enclosed.
Please feel free to contact me if you have any questions regarding these comments. I look
forward to receiving the items including the geological assessment to review. There may be
other concerns and questions after the items are received.
Sincerely,
(Signature) (Date)
Russell W. La Force, P.E. �c,,`��oF as'S'i,TC 0
Design Engineer .A,
Vector Engineering, Inc. °C Z rn S� oZ
309 Washington Street NE a265i
Olympia, WA 98501 ��� s� ,
(360) 352-2477 `O�'tIS AIL
ENv\
,
tip �f
.,,,,
EXPIRES 05.25- oil
Page 3 of 3
X:\7000 Files\7054 Mason County Gcotech Reviews\7054-009 Mason_Co(Ferreira)\Admin\Transmittal Lctters\Geotechnical Report
BLD 2007-00493 Review Acceptance 070905.doc
6740' + ,00
NOTE:FOOTING no7NA
1lJ�LL`J11E - DIO .
:�el" ' r ..'PLANNING
INSMUS7 BE �J' /
USED N CONJUNCTION WITHTION CAs>PEAT _ .. - y`�-rRENCHEs AND Musr MAPITvr.(MIN> l 2 a0 ON SITE
SETBACK FROM ALL DRANFPONENTS ROVENOTE:ROOF TOP DRADYS N ,MUSTr �° yy ;. h,EITHER DAYLIGHT INTO THE R MUST ��77 _ lCBE USED IN CONJUNCTION WIFILTRATIONkTRENCH,.MANTAINNG 10FT.( BM-KS "..
FROM ALL DRANFJELD COMPONENTS ////��,, +` •F Gr0" ,, r F
NOTE TO HOMEOWNER OPER I ' 4r
CLEARING N THE DRANFIELD AREA TO BE DONE +^IY) �•IF'l •y i I 5r j. 'y =
UNDER THE SUPERVISION OF THE INSTALLER t-+ VVV`, i\.
MNUfUM HOME SETBACKS TO BE VFMFIED BY TW
•BUILDING DEPARTMENT SASSUW NO LIABILITY
0'(TREATER
yY
TH[S DESIGN IS NOT A VEY 1 .,� r/ �C 110
AI.L PROPERTY LINES AND DII.IINSIONS.AS SHOWN �F 3 —SO%- - - - lo.
ARE FROM INFORMATION SUPPLIED BY THE CLIENT
OR COUNTY OFFICE.WE ASSUME NO LIABILITY FOR QO \ LOO 7° /
Vau�ennwcnBYACTUL OILUrmE \J �D� � .'�'
RECENTSURVEYS. -- �I► 4co
\O,Q
ATER ERVI - KEEP 10' (MN.) FROM ALL
""AINFB;LD TRENCHES AND SEPTIC TANKS AND 1k�� 4�11 /1 - \
PIPES OR ENCASE WITH SCH 40 PIPE.ALSO PROVIDE e�, CJ J v �• 1 w-�F- r
CRUSH PROOF SLEGVE UNDER DRIVING SURFCES. �n \
* tiW I
_W W W W-
` f
1 tAA-1 JJEr-15a VM7XrArtr,1-r 1 N
I �
t:-�:U'-fT. °
PLANNING:
do Ro of) ALL SETBACKS ARE MEASURED
-- - ------ FROM THE FURTHEST
INVERT ELEVATIONS PROJECTION OF THE BUILDING
FIN. FL. = 9-7.5
STUB OUT = q5,o XWJAOFBF- v--U-06
SEPTIC IN = g4.7s 1" A' CLIENT: -
D'-10'FILL O-✓FI-v/q FE( -�I�>�
OUT = '14.93 I(Y-21-FINE OIL GRAVSAND 14120 gT�f{,)E.G�.h(lcf
21'-84'FINE GIL GRAV.SAND 611 A A
L.RT (,E, ^]2•Z5 P133 030
TH.g. SITE ADDRESS: DATE:7-1-'O
= D•-37'OR.LOAMY GRAV.SAND PARCEL NO.: D 2 .
37'-81'FINE GP-GRAV.SAND REV DATE:
TH'C' PENINSULA 5EP77CDESIGNS
Cr-14•FILL 8R4DFORD E..SJN17N
dLL TANKS .MUST HAVE R/SERS TO FIN7SX CRADE 14'-24'DR LOAMY GRAV.SAND P.O.BOX1444,GtGHARBOR WA a.— PINT -53 8512178
24'-70'FINE GR GRAV.SAND FERREIRA h117298 PG 1 OF 2
Flood Canal ,�+� +' `. Reddish txovm silly loam,burry sit(S,9 Typiol poas-ee�an Ad
7 98to 100%sod beaning morsa,r nl �+coo od ----�-
r�, � `' � sipsttbrylamw
k 23a E.Baka Ct Preserve all Veer and vegetation
� on the 50 to 60%slope --
Ught 9reY very dense glacial to(GV%LW I '
N 6 !wih en allowable soil hearing capacity d
Ito 4000 psfi and a 5 to 7%moish e b BOlL �'..,,...�.
T � Botlmlde/bdYpa alW a I I�,',• /% rest on lne GUOfSTIRilm
5'+algY�Mp g \,���C�(i�• dose PsY gleoal 07 M
li madrrxxn wppon d to
lowdsb—
N �_� Note:This engineer alias oe calhd out
R. the excavation f«the fonda ution
\ duvg
•V� .\ end abo dust PRIOR to it.first concrete
.Old loggiing pour to verify that the forxdalion is belo9 a
\ oorwtnchd on 11ND15il1RBED glacial
abid rued till material and prepare onste report and
verify that the 20'setback is met as
1 _ indicated on this drawing.
C�OLOGIC AtW .�_OF THE SffE '—___ t mwwdeeMuteloWttn the dYet9on
Relatively level in this area and,therefore, -\ (i10 hwn the prdpoeed tttleldeltp) E
does not Present itseff as a landslide hazard.
\ /Isrrg' hale,or old Olden an ft bSO BD%a�ldp~� Qi\ 0 0
'•,\'\ yip.. No evidence of sdl erasion \.
- � $�� gmvd fiswres,«abler sign \ 3
b mlahi creek,
in the area o1 the
seasonal nxcelc. \ LF4
500'Datum $$S
Elevation ,
Preserve all trees and vegetation T x T x.10'infiltration
on the 50 to 60%slope -trench(sled with 1 to J' '..} S,
din.ban rock and lined `U.
465 wl a geotextlle fitter faxic I Parcel#1220 Irmo 00T2 F'6
480 Elev.
Flev Elev Elei mirt 20' older bw
E1ev. 495 Bev d
47=9a penile
F e1 Y i"L— 29 sdbad,it. Sol Log g'
€�aR�i�tl�rJ�€Fr�1tlGlrJtl. ' "50to60% embueonsnt —
Drt A vesvey rerNarke
dlope d s j Proposed ease.."slope tanlhlsr A \
6vFN P�Oq`� • / � 1 ti��
y�C��ogwtisy�ticr�t � �� fr3¢�X�
lt
i
Propose
Septic dranfield
20NpL Preserve all trees and vegetation
on the 50 to 60%slope
cxPtaES /�9 W uj
U
GeoUchnkal Fndtrueerind Report per Nov lfaaon 2L lYM Resource Ordtnarnce
s.abn 77 of 100E updated on December 27 loot
(1)General Geolo*Conditions and upland Gisorn pf oiogy, The entire
Pugal Sand region has undergone four rtrepr glacial advances and recessions (8)Racortrnendanona for to prelowa"On of a detailed clearing and
With the last A'de Occurring appraomataly 20,000 years ago leaving glacial till Wilding Plan which specifically k iertN{s vegwdon to be renovedt
I comPected coarse sand deposits as observed on the site.These glaoers ,schedule of vegetation removal and replacing,and the method d
were over sandy
a mile high andder therefore,Placed heavy pressures on the glacial ''99"ati�"d�Proposed building site is already in a cleared area
tins and sandy deposits order these glaciers. Mato vegeatcn required it is remrrrnended that
The upland 9 Phobgy consists of an 8 to 10 deep inured seasonal the ewsbng surface grasses and rods be scarified and removed from the sde
unnamed creek that flows from south to north towed the Hood Canal. The upland Prior to cnnsrliCilm If oxhsruction occ res during the rairy season from
area is releiiv ely level with no evidence of previous slide activity such as ground November through May.any loae ground will need to be covered with 8 col
fissui or hunmocky seas. Dense forest vegetation in the upland region vsglueen to prevent soil erosion
inoasses slope st"ItY due to their extermve root systems and canopy cover
which protects the soils from direct rainfall and helps to dawdler the grand (8)Recnnenardatl«n for the prepratl«r,of a dddbd temporary
trough the Process of evapotranspiration trough their roots and tree limb,. I°alon I plan which 0-dfNs the apscNk mbgsdrg measuresThere p
Am no indoations d vvetlards,surface d subsurface seeps o standing lards to be ripple harmful construction rnha to Woted
tiro stops iron erosion'water except for the seasonal urnaned seek just meritioned Due to the reiaovely Rio to s andnh rmf l activities on the site,
flat upland terrain and the absence of wet soil conditions,the likelihood of at*Y gectextile siltation fencing shall be p
slide activity is essentially none usternt. Placed on the downhill side of the building site to prevent soil erosion d the
The specific soil type is a reddish brain silty ban,berry sit(SM)with an anent. In addition,geotextle s nation fencing shell be placed on both
allanable soil bearing capacity of 1000 psf and a 8 to 10%moisture corta i. sides of the building pad it is recormhended that initial oo.#ucb.flake
Belau 2-1/7 these is a light gray very dense glacial bit(GW-SM)with an a",P'. Place dMrhg Ne drier times of the year from mid May to mid October and that
soil beang capedty of 30DO to 4000 Psf and a 5 to 7%meisture content the residence be weathered in by the brgkrting of November, If rain is
expected all bare goad is to be protected with R mil visqueen to minimize
(2)Sits plan of the Importad davelopsrd and gsobgk feahaes. sod erCG0n of the building site and the resulting water runoff to be directed EE
The site Plan on sheet 1 of 2 show the location of the proposed single story MAY FROM THE SLOPE. J8
residerhce along with the Proposed d^'evvaY to the 2-car garage. N
(3)A d (10)M uhnYyab d both orb-sfte and ol'felb Impacts d the pPPPW
log exploratory bet hob.On sheet 1 of 3 the test hole location and dwiW0p"b'K Since the building site is mostly in a cleared area already,
the resulting soil lag are indicai. there win be minimal on-sae i
mately 200 b 2517 mheCi_Also,the hPo r in
sae itaet b.therefore,
(4)Area d away from the neaes neighbor t.the was end,err noire,
Proposed development,tgzard thoxundedes,tluffefa and stxfi things as(TJfl3tllr1lon noise,wbmtim,exhhast etc.W+11 Insure rrirlrnal
setback dell—an a geologic map.Refening to the geologic map on impact to the neighbors. Nearly all the trees wit be preserved as recommended 5
sheet 1 of 3,a 110 1ldlfaf b provided from the hx,,m d creek located on the in Nis geotachnical angineenng report except for those that are in the septic
east and of the Property t0 the proposed building site.Also,a 20 setb ie*will dra rifield area as indicated on sheet 1 of 3. ;$S
provide adequate protection from slides as indicated on the geolcW map. The (11)sl6catlons d OrW derveloprned c(xditiorha such as F fs
Proposed kxre of fbn the drat rf"d is locaied in a ralatNey level area a pec
nd is ,vagetatve d(
also tar av'aY from the well as required try the Mason Carly Heath DeM management drainage.erosion control,sod buffer widths.All sulaoe
water runoff from the roof shah be dreded into a 3'vnde by 3 deep by 10 $$
(6)A mlydnaan of ons cross secWn at a scab which adequately rieplcb Ong infitraton trench as indicated on sheet 1 of 3.This infiltration trench shall a
the subsurface profile,and which Ind«porabss the dOWl-d proposed be at least 30 from the edge of the arbahicnherf and WAN elbw the water to
perodate bade into the graurl and eventiuel Q^ R
grads changes,A detailed cross section is shown on sheet 1 r 3 that bare areas after dorl9Nlrtldn shall be ly--drags to prevaf sal erosion a?1
indicates that the top two and a half feet consist of e redden txown slty loern, vegeratsd o treed to
loamy sit ISM with an alkxvable beanng capacity of loco Ps and a 8 to 10% with Plants that are indgenCt s to the area A 110 buffer shall be maintained N N
mdshre ooreal followed by a 6 to 7 hod layer of W gray very dace glacial between the"a Pad seasonal creek to the east and the proposed residence.
bur(GNLSM)with an albAeble soil bearing capacity of 3000 to 4000 pelf In i6
UNDISTURBED state and a 5 to 7%insitu moisture comer (12)is 0 otRecomher proposdalloneed
for Uw preparation of stn coon f t e mfilt«
dlebib d other prgaoeed rnftlgetl«t The construction d the infiltration
(6)Descriptor and results Of slope stability-Wyss for both the stall, farce referred to in(11)above shell be lined vIN geofmotile filter(edit to
and sel is loading conditions and should examine worst case tailors. prev"the 1 to Y darleter drain rock from becoming fified with silt that Wald I
The anatysle should Include the Sknplffled 9bhop's Method of Clrcbs. affect Percolation of the surface water moot batik into the grand wet,
As irdigtad on engineering sheet 3 of 3 a detailed slope stability has been
Pedonmed for both the static and Crynartic cases using a modified form of the (13)A site map dkswe to scale shoMng the property boundatas,scab, l
Simplified Bishop's Method of arcles. The resultrg factor a safely for the north arrow,and the locator and nature of adtlng and proposed j
stair rase Was 2.14%4 h was greater than 1.5 and,therefore,the static slope dweloprnerd on the site. Refer to sheet 1 of 3 for the site plan. Nate that
stab ilty Paclo of safely was considered satisfactory. Simlarty,for the dynamic the sae plan and geologic M3P with the elevation contours end other gealata m
Or seismic 0 i 5 was the Ong factor of safety for a tic sta analysis oneffidad of has been included on the same plan. 8
oomµled to be 1,58. Since tls is eater than 1 1 the factor Of
safety Of 1.58 was considered satisfactory.
Y
(7)Reabictiorhe on piecemerd ofdrahhage features,septic drain fields and
8ry
compacted flta and foodrgs,and buffer and setbaclm iron IWWWIde
hh®rd area.As irhdrtded on sheet 1 of 3,the infiltration trench wig mead to
be located at least 30 back from the edge of the arbwkn,,l to ensue I¢`3
over all stability of the slope. The sePtic draidheld is lasted on a relatively level
area ate indicated near the base of the slope ad shall also be located at leas
100'away from the Weil.
Footrgs s eU be constructed on UNDISTURBED glacial tig. This engineer shall W
be called out to the job site during the excavation for the footings and,again,just
Pnor to the foobng Pour to ensure that the footings are resting on UNDISTURBED
native glacial till. 11
Slope Stability Calculations (at Cross-section AA
20'
15�
Rotational Failure
Plane tied
NPha=31 deg(60°,6 slope)
1. Compute factor of safety(FS)against slipping-Static Case(Ref: "Stability Charts for Uniform Slopes"by
Radoslaw L.Michalowski, FASCE) - Stability Charts have been included with this slope stability analysis.
From Figure 3"Stability charts for uniform slopes"the following parameters are known for native glacial
till materials:
c(cohesion)=250 psf, gamma(insitu unit density)= 142 pcf, H(height of slope)=30 ft,
phi(internal friction angle)=38 deg, then
c4gamma x H x tan(phi)]=2501(142 x 30 x tan 38)=0.075
Then for a 31 deg slope from Fig. 3:
Frtan(38)=2.74 or, F=Factor of Safety= 2.14>1.5 OKAY
2. Compute factor of safety(FS)against slipping-Quasi-Static(seismic)Case(Ref: "Stability Charts for Uniform Slopes"
by Radoslaw L. Michalowski, FASCE) - Stability Charts have been included with this slope stability analysis.
From Figure 4"Stability charts for uniform slopes"the following parameters are known for native glacial
till materials:
c(cohesion)=250 psf, gamma(insitu unit density)= 142 pcf, H(height of slope)=30 ft,
phi(internal friction angle)=38 deg, then
c4garmna x H x tan(phi)]=25U(142 x 30 x tan 38)=0.075
Then for a 31 deg slope from Fig.4 for a quasi-static analysis coefficient of 0.1:
Fftan(38)=2.25 or F= 1.76,
For a quasi-static analysis coefficient of 0.2: !
F1tan(38)= 1.78 or F= 1.39
As a result,for a quasi static analysis coefficient of 0.15,the Factor of Safety, F=(1.76+1.39)12=1.68>1,10 OKAY
i
—Slope Stability Analysis for property located
at 230 E. Baker Court,WA 98528 Prepared by: Morta Englnaaring d Tasting,Poe 250,ocean snores,M 98569
Prepared for: Joshes Fartstrs (360)289-OW, (800)590-09`a8,(360)289-9682 fax,Smorta@AOL.Mm
:1::
14120-49th Ave Ct.NVJ i
Gig Harbor,VA98332,(253)312-4108 cep
Aug.
2,2007 AnWTzed by SPM Pape 3 of 3
i
i
Slope Stability Calculations (at Cross-section AA
20'
/ Rotational Failure
Plane Not to scale(NITS)
/ Alpha=31 deg(60%slope)
1. Compute factor of safety(FS)against slipping-Static Case(Ref. "Stability Charts for Uniform Slopes"by
Radoslaw L. Michalowski, F.ASCE) - Stability Charts have been included with this slope stability analysis.
From Figure 3"Stability charts for uniform slopes"the following parameters are known for native glacial
till materials:
c(cohesion)=250 psf, gamma(insitu unit density)= 142 pcf, H(height of slope)=30 ft,
phi(internal friction angle)=38 deg, then
c4gamma x H x tan(phi)]=250/(142 x 30 x tan 38)=0.075
Then for a 31 deg slope from Fig. 3:
F/tan(38)=2.74 or, F=Factor of Safety= 2.14>1.5 OKAY
2. Compute factor of safety(FS)against slipping-Quasi-Static(seismic)Case(Ref: "Stability Charts for Uniform Slopes"
by Radoslaw L. Michalowski, FASCE) - Stability Charts have been included with this slope stability analysis.
From Figure 4"Stability charts for uniform slopes"the following parameters are known for native glacial
till materials:
c(cohesion)=250 psf, gamma(insitu unit density)= 142 pcf, H(height of slope)=30 ft,
phi(internal friction angle)=38 deg, then
c4garnma x H x tan(phi)]=2501(142 x 30 x tan 38)=0.075
Then for a 31 deg slope from Fig.4 for a quasi-static analysis coefficient of 0.1:
a
F/tan(38)=225 or F= 1.76, �
For a quasi-static analysis coefficient of 0.2:
F/tan(38)= 1.78 or F= 1.39
As a result,for a quasi static analysis coefficient of 0.15,the Factor of Safety, F=(1.76+1.39W=1.58>1.10 OKAY
Slope Stability Analysis for property located at 230 E. Baker Court, M 98528 — -- — Prepared by: Morta Engineering 6 Testing,POB 250,Ocean Shores,VA 98569
Prepared for: Joshua Ferreira (360)289-0958, (800)590-0958,(360)289-9682 fax,Smorta@,AOL.com
14120-49th Ave Ct.NW _
Gig Harbor,Wq 98332,(253)312-4108 cell Aug.2,2007 Analyzed by: SPIV
Page 3 of 4
f M 6 1 N E E f I N 6'��I N C
309 WASHINGTON STREET NE • OLYMPIA WA 98501• TEL:360 352-2477• FAX: 360 352-0179
www.vectorengineen.nginc.com
RECEIVED
August 10,2007 AUG 13 2007
Mr.Robert D.Fink,AICP MCCD - PLANNING
Mason County—Department of Community Development -
Mason County Bldg 1
P.O.Box 279
Shelton,WA 98584
Subject: Geotechnical Report Second Request for Additional Information
Permit#:BLD 2007-00493 rzi�
C r'
Parcel No. 12207-75-90072 —
Applicant:Joshua Ferreira
Planner: K McAboy -
VEI#: 7054-009
Dear Mr. Fink,
The geotechnical report dated March 21,2007 and revised geotechnical report dated August 2,
2007 prepared by MET(Morta Engineering and Testing), P.O. Box 250, Ocean Shores, WA
98569-0250 for a proposed residence with septic system at 230 E. Baker Court, Belfair, WA
98528 was received and reviewed by Vector Engineering,Inc.
The revised report included several items for which no further response is necessary. Other
items are still needed. The completed items are:
1. The report includes an incomplete site plan, which identifies some of the important
development and geological features. More detail is needed as per MCRO 17.01.100
E.5(2).
f
• The response is adequate.
2. A cross-section,which depicts the subsurface profile,was not provided as required by
MCRO 17.01.100 E.5(5).The cross-section provided depicted the surface only.
• The revised cross-section is adequate.
3. The report includes a slope stability analysis performed with static and seismic f
loading conditions. The slope stability analysis was used on one type of soil, a dense {
light gray glacial till having a drained shear strength value of 300 lHM2,a phi angle of `
41.3°, and a dry unit weight of 133 lb/ft. The phi angle is higher than what was used fk
in other reports. No loading factor for the building appeared to be used. The report
also mentioned the existence of a topsoil of reddish brown silty loam,loamy silt. The
Page!of 3
X:\7000 Files\7054 Mason County Geotech Reviews\7054-009 Mason_Co(Ferreira)\Admin\Transmittal Letters\Geotechnical Report
BLD 2007-00493 Second Requestdoc
. 1
2• The report includes an incomplete site plan, which identifies some of the important
development and geological features. More detail is needed as per MCRO 17.01.100
E.5(2).
3. A geologic map of the site showing the area of the proposed development, including
the boundaries of the hazard, and associated buffers and setbacks was not provided.
MCRO 17.01.100 E.5(4).
4. A cross-section,which depicts the subsurface profile, was not provided as required by
MCRO 17.01.100 E.5(5).The cross-section provided depicted the surface only.
5. The report includes a slope stability analysis performed with static and seismic
loading conditions. The slope stability analysis was used on one type of soil, a dense
light gray glacial till having a drained shear strength value of 300 lbf l,a phi angle of
41.3°, and a dry unit weight of 133 lb/ft. The phi angle is higher than what was used
in other reports. No loading factor for the building appeared to be used. The report
also mentioned the existence of a topsoil of reddish brown silty loam, loamy silt. The
slope stability analysis used was not the recommended Bishop's Method of Circles.
The cross-section should be longer to include the areas outside the slide area. The
method used was a limit equilibrium version of"Simplified Wedge Failure on Planar
surface with Length L." page 775 figure 20.2 Civil Engineering Handbook, CRC
Press, 1995. It is recommended a new stability analysis be run and justification of the
soil properties be provided. MCRO 17.01.100 E.5(6).
6. The report includes recommendations on restrictions on placement or proper drainage
features, septic drain fields and compacted fills and footings, including recommended
buffers and setbacks. No concentration of runoff is recommended and discharge of
runoff should be piped in a closed conduit install on the slope face and taken to an
appropriate spot beyond the toe. The septic drainfield should be located at the bottom
of the steep slope. The house in the report was recommended to be 20 feet away from
the top of the slope. This appears to be in conflict with MCRO 17.01.100 D.6(a)
which requires a 50 foot buffer of undisturbed,natural vegetation.
7. No recommendations for a schedule for vegetation removal and replanting and for
method of vegetation removal other than careful limbing were provided and
preserving all trees and vegetation not in the drainfield area or in the proposed
driveway.MCRO 17.01.100 E.5(8).
8. The recommendation for a temporary erosion control plan needs to include specific
mitigating measures to be implemented during construction to protect the slope from
erosion,landslides and harmful construction methods. MCRO 17.01.100 E.5(9). The
report only mentions geotextile erosion control fencing.
9. The report needs to include recommendations for the preparation of structural
mitigation or details of other proposed mitigation MCRO 17.01.100 E.5(9).
i
10. No specifications for final developmental conditions were found in the report as I
required by MCRO 17.01.100 E.5(11). A summary of final developmental conditions
needs to be provided.
11. The report includes a site map drawn to scale showing the some of the property
boundaries, scale, north arrow, and the location and nature of existing and proposed
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XA7000 Files\7054 Mason County Geotech Reviews\7054-009 Mason_Co(Ferreira)\Admin\Transmittal Letters\Geotechnical Report
BLD 2007-00493 Review Requestdoc
development. A more complete site map showing the entire property boundaries is
needed MCRO 17.01.100 E.5(13).
In the reviewer's opinion, the report does not provide sufficient information to determine the
project will not decrease slope stability at the site or on adjacent properties and the risk for
such occurrence would be minimal.
The conclusions presented in this report are based on Vector Engineering, Inc.' understanding
of the project requirements. Vector Engineering,Inc.warrants that its services were performed
with the level of care and skill ordinarily exercised by members of the same profession
currently practicing in the same locality under similar conditions. No other warranty or
representation,expressed or implied,is included or intended hereunder.
Please feel free to contact me if you have any questions regarding these comments. I look
forward to receiving the items including the geological assessment to review. There may be
other concerns and questions after the items are received.
Sincerely,
—RuwaN• �'cSW� 9 ?,00`7
(Signature) (Date)
Russell W. La Force, P.E.
Design Engineer
Vector Engineering, Inc.
309 Washington Street NE
Olympia, WA 98501
(360) 352-2477
Ii
I
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XA7000 Filcs\7054 Mason County Geotech Reviews\7054-009 Mason_Co(Ferreira)\Admin\Transmittal Letters\Gcotcchnical Report
BLD 2007-00493 Review Request doc
6 1Ca 1' Reddish brown silly loam,loanry silt(SM) -
Mod Caf W � -Movable soil tearing capacity:7000 pef
2' 6 to 10%moisture content angle say-am
�J1 3 Preserve all bees and vegetation O•�.Ji�:
2MEBetwct on the SO to 60%slope `�p;,�•�.�� -
4' Light grey 1e7 dense gladal III(G V-SM) c'"•^�•"'. -
_�-with an allowable soil beanng capeaty of
N S —- 3000 to 4000 psfl and a 510 7%mofsaxe 6010 BO *p -
6 I a content. i
Bottom foo of.( tishalls shall
\n rest on the gic.]tRto
T ��j�\��� � dense gray gledel Gtl fo(
VIdNIY Map 6 lou deb—support of theg•1J / C
. \ Nde:This engineer Shal be rated out
N —� .\ during the excavation for the fouMafion
and also just PRIOR to the first concrete
\ pour to verify that the to ndaUon is being O
u
\ corrstnxded on UNDISTURBED g1wal
fit material and prepare onsite report and
Old kgoing vYA - `.4y3:, verify'Mat Me 20'setbadr is met as
ydd red indicated on this drawing.
- �_ Unner"ed seasonal creek
in
GEOLOGIC MAP OF TFE SfTE \ (t m the proposedresdenca)
Relatively level inthis area arid.therefore
does not present itself as a landslide hazardNo wividaim .
IeT-o" Learnt _— A,
tees,
or old dldee m ge 50 b 60%slope.1' No evidence of Sal erosion, .•Q
b,C gravid ft.—,or other signs 't
of instability in the area of the
o aeasonal seek. S 8
% F S
� Elevation �{�q,, � ■ ...
0'x 3'x 10'infiltration qbf \
Preserve all bees and Wegetetion\�\ - trench filed with 1 to 3' Puae1�7207758 OD72
� -
on the 50 to 60%sty �r dia.drain rock and lined \ 52
'I 485' w/a geotextile fiber fabric. \ FI
4W
47S Elev. Bev. .4W '. min.20
Bev. Ebv. ,`,4W Bev. \. t a iG
y 7
SON Log E*stkV 25 yr __ b
old Ceder tree
->
_ Preserve AN beet and"gib ion 2,r a
50 to 60% n Cue 50'buffer zone �- g� Driveway anf+erne
i dovwavard
- 50 setbad from- - _- Bd Log eaeurer4
slape embankment edge
A per MCRO 17 01 100 Proposed I �\
SO selatlt ham y„�yM,
P/2y07 from toe utarMetile rarnber r
Harerd MCRG
•....�,' 17.01.100 D.6(a) ' 3 - - --- Deddcal
viTl P M7 ♦ tranefom
WAS:f7h r.� Proposed Preserve all bees and vegetation $. _
Sepbc dra0eld in des 50 buffer zone I 14 4tiy, R "vj
y `V
terwea.Nerd 4ey
30758�
Qv,�Q:IST£C�r'R'L ul
C{S�ONAL
Ex PIPEa / / 1g
Geotechnka1 E»pineadnq Report per the Mason County Resource Ordinance
Section f 7,01.100E updated on December 27,2OD6
(1)GanerN Geologic Conditions and Upland GeomorWrology.The entire (S)Recortxrendatlons for the preparation of a detailed clearing and
Rio Sand regon has undergone by major glacial xNatces and recessions gradirg plan wnkh specifically identifies vegetation to be reaoved,
with the last cycle—rig approxin-ety 20,000 years ago leaving glaoal till a schedule of vegetation renio cal and replarkkg,and the method of 3
and compacted coarse sand deposits as observed on this site.These glaciers vegetation nrnoval.The proposed hilding site is already in a cleared area
were over 1/2 a rude No and,therefore,placed heavy pressures on the gaciai with no removal of trees or mator vegeabon required it is recormnanded that
lids and sally deposits under these glaciers the exstirg surface grasses and rods be scarified and rerttoved from the site ! �!
The upland geomorphology consists of an 8 to 10 deep incised seasonal prior to construction. it construction ocaies dump the rainy season from
urnared creek that flows from south to north toward the Hood Canal. The upland Novem th ber ough May,arty bare ground will need to be covered with 6 mil
area is relatively level with no evidence of previous slide activity such as ground visqueen to prevent soil erosion. .�.
fissures or hurry"areas. Dace forest vegetation in the upland region
increases slope stabilKy due m their extensive rod systems and canopy cover (0)Recornmendatloos for the preparation of a detailed ternporary
which protect the soils from direct rainfall and helps to dewater the grand erosion control plan which klerrbfies the speclflc mitigating reassures L
trough the process of evapotranspiration through their rods and tree limbs. to be InrpWrwftd during construction to protect the slope iron erosion,
There was no indicators at wetands,surface or subsurface seeps or standing landslides and hamkul construction methods.
water except for the seasonal unnamed creek just nxer>tiened.Due to the relatively Prior to co stnocton acWbes on the site,geotextile siltation fencing shall he a
flat upland Leman and the absence of wet soil conditions,the likelihood of any paced on the dowrihill side of the buiding site to prevent soil erosion of the
slide activity is essentially nonexistent emhsrkmark In addition,gerkexhle siltation fencing shall be placed on both
The specific sod type is a reddish brown silly loam,berry sift(Sid)with an sides of the building pad it is moormerdsd that irobal mretrtudion take
allowable soil bearing capacity of 1000 pst and a 8 to 10%moisture content. pace dung the trier times of the year from mid May to mid October and that
Below 2-1rZ there is a fight gray very dense glacial till(G1 V W with an allowbie the residence be weathered in by the begirrting of November. if rain is
soil bearg capacity of 3000 to 4000 psf and a 5 t0 7%moisture content expected all bare grand Is to be protected with 6 mil visqu sen to min it ize E
soil erosion of the building site and the resutNhg water nndf to be directed g
(2)Ski Man of the Important dewlopnsrk and geologic features. MAINY FROM THE SLOPE. o
The site pan on sheet 1 of 4 shows the loratbn of sue proposed single story i
residence along with the proposed driveway to the 2-car garage. (10)An analysis of both asks and oft4lta Impacts of cis proposeddeve Si a
(3)A leg of expioretny test tole.On sheet 1 d 4 me test hole location and bhere 11 be Since the bulb is mostly b �see al
there will be minimal dfFete impact.Also,the bin site itself is
apprm-
the resutrg soil log are kxicaled. matey 200 to 250 away from the nearest neighbor in the area and therefore,
such things as mnstrumon noise,vibration.axhaust etc will have mr maJ g '�
(4)Ana of proposed devOw ell,hazard boundaries,buffers and inpad to this neighbors. Nearly all the trees will be preserved as recorurended �
setback delineated on a geologic map.Relering to the geologic map m in this geoledhr"engineering report except for these that are in the septic
sheet 1 of 4,a 110 butter is provided from the lrnanhed creek located on the drainfield arw as indicated on sheet 1 of 4. g
east and of
property to the proposed building site.Also,a 20 setbadk will
provide the
protection from slides as indicated on the geologic map.The (11)Speef cation of final developrne t conditions such as,vegefaW e
proposed location of the drainfield is located in a relativeey level area and is rna agansrk,drainage,erosion control,and buffer wkkhs.Al surface
also 100 away ham the well as required by the Mason Canty Health Dep. water runoff from the roof shall be drech5d into a 3 wide by 3 deep by 10 R
bug infiltration branch as indicated on Sheet 1 of 4.This infiltration trench shall
(5)A mkkmum of ors cross section at a scale which adequately dapkts be at least 3C from 0e edge of the errhbarhkrnent and will alloy the water to a 9
the subsurface proft,and which Incorporates to detels of proposed percolate back into the grand and a erkuaily recharge thhe grand water.Al t n 13
Wade charges.A debated cross section is showrh on sheet 1 of 4 the bare areas after construction steel be vegetated or treed to prover[soil erosion
indicates that the top two and a half feet consist of a reddish brown silty,loam, with parks that are indigenous to the area A 110 buffer shell be meirtained
Barry,siht(SK wth an allowable bearing capacity of 1000 pet and a 8 to 101/6 between tie unarmed seasonal creek to the east and the proposed residence. Z
moisture content followed by a 6 to 7 bat layer of high gray very dace rgaeal
ill(GIµW with an allowable sail bearing capacity of 3000 to 4000 psf in its (12)Recommadi tlors for the preparation of strrctaal nAt{peton or
UNDISTURBED state and a 5 to 7%insibu moisture content details of other proposed mitigation The construction of the infiltration
twice referred to in(11)abae shall be lined with gectextile,filter fabric to
(6)Description and results of slope stability andysu for both the stalk pre oil the 1 to W dameer drain rod(from becoming filled with silt that would
and seismic loading conditions and should examine wont case failures. aced percolation of the surface water mrot bad(rotor the grand water.
The analysis should Irclude the Sirnplffled Blehop's Medhod of Circles.
As indicated on engineeing sheet 3 of 4 a detailed slope stability has been (13)A its map drawn to scale showing the property boundaries,scale,
pertonad for both the static and di r irm cases using a modified form of the nand arrow,and the bombe and nabs of existing and proposed
Snplifiad Bidhop's Method of resultingrcles.The resulting favor ofsafety for the development m the site.Refer to sheet 1 of 4 for t pan.hhe site Note that
static rase was 2.14 wh ish was
greater than 1.5 and,therekne.to afffic slope the she plan and geologic map with the elevation contours and other geodata
stability factor of safely was considered satisfactory Smiady,for this dynamo has been included on the sarre plan. Q
or seismic the resitting fades of safety for a quasi-static arabysis coef6dak of
0.15 was computed to be 1,58. Since tis is graster tan 1,10,the factor of 4 H
safety of 1,58 was mredemd satisfactory
(7)Resiekbore on pacarrert of drainage features,septic drain fields and PA R
canpectsd lab and footings,and buffer and setoedce from ladellde
hazard arems.As irxi®ted on sheet 1 of 4,to tmfikatron trench will reed to ,
be located at leas 30 back from the edge of the embanWient to ensure gg yy
over am stability of the slope.The septic drainfield is located on a relatively level N
am as indicatod near the base of the slope and shall also be located at leas
100 away from the well Wit:
Footings shall be mufnuded on LMNSTURBED glacial bfi.This engineer shall I
be called out to the pb site dung the excavation for lie footings and again,just rL
prior to the footing o"to ensure Ihat the footirgs are resting on UNDISTURBED
native glacial till
lea tar a 1Ba lea
Q 4
R
p�N
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m
Bouldwy Lkw M Property Located at 230 E.Baker Cart pied M MET(MWU F gW—.g-4 T-drV)
Ballet,WA 98528,(Parcel ff.1220 7759 0072) PO.Boa 250,Ooeen Srwres,Vf 9&SM50
A4CR017.01.100 ES 13 _ (e00)590-09M,(350)2W9ee2 fax,Snwna@AOL w,n fiob 1• �.
Prepaad for. Jeellru Fatah Ap.21,:9 — a W a V Sr
14120-49N Me CL NW 2 � 1. p Ole FMItor,NJ19e332,253)3124109 cal Rev Aug.24,20a!
Y � Lco7-0&49 3
K Sw1
Food C11W _nf +• :� Reddish brown silty loam,loamy"I(SM)
- Allavable soil bearing capacity:1000 psf
7 ` 8 to 10%moisture comer.
7
230 E.asks Ct
Lghl gray very dense glacial till(GW-SM) S n*story nantbla
N IF .I —with an allowable sal bearing capacity of ----
I 3000 to 4000 psft and a 5 to 7%moisMa Preserve all trees and vegetation �-
I'yIII lT �I ndent on the 50
w to 60%slope ,-
o1 all footings are to rest on the UNDISTURBED Y �'
g l 50 to 60%amps dense gray glacial UI for m--scgpon of the laedation.
u TYPIL11 Claa4aaWan Ad �'
>r
N
Unnamed creek in this direction ^�`
ITYT,wErtalna ft Racism(
Garraral Gaaogk Cordplota.The entire Puget Sound adarg
fo«major glacial advances and recession vrh the�ocanirg Found.RacornyndaUory.p is mourn tendad that the feurdagen E
aPpro-matefy 20,D00 years ago leawrg glacial fill and compacted coarse UNDfSTt1RHm hard light gray glacial till for rradmtm suppot and tlsa Ihe�be placed on 9
N' sand deposits as observed on the site.Thasa glaciers war,mar 12 a mile be at least 18'witle.Is geolednicat engine«to inspeq the f000ng fonmvo pq pq t m •
high"ther,fore,dated heavy pressuraS on the glacial fills and sandy cont«ele pour to ensure that the bottom of footing is resting m undisturfied,,.dialtill Salo.o. deposits uder these glaciers. 2 a
. Bp-Mc 8-11 pig y ( ) C—eft aRecarmnend a minim m of 3500 pai concrete.i.e.,5-12 neck.d oemerd par yant. I dD
soil bean ryq"Reddish broom N barn.loam silt SM wdh an Ample Stomp Shan not exceed 4-at the bme of the pour.
in rig c�an1Y of I—psf and a 8 to 10%moisture tatter.Belau 2-12•
i capacity
iit a light gray wary derue glacial tilt(G WSM)with an ahowble,soil been, I a T1te septic drainflea is 1«alad at least 100•away rmm the mrmpmNy weY. g�
crtpaoly d 3000 to 4000 psf and a 5 to 7%moisture coM-t Pnmay and reserve drainficas et the bottom of Its 50 a 6p%
500'Datum CArtsid«Bd satisfactory. slopes am
Elevation Groundwabr Condition.Them were no ndication,d sort"«subs«face a
groundwater such as Seeps or standing water due to the dens,last Hoer SMGck.If is recpnmended that cite setback hom the bade d the house to the top of the slope 5
whidt has the capab4iry to soak up la ct
rge a ldonts d water especially due to be at least 29. gr
the roof systems d the D«glas Firs and Aid—in the area. -
485'
El- Landaltd.A v� cUvky.Tftere was no evidence d oat or new lard vide Tns and 4kw old cedllg it a on the 50 m 60%slope and there was n o le a arhvdy, o-datloo.Reserve all trees and vegat9b Win the hainfield area«_ leaning ptstd braum bee sciirp In the fieca�iity to nave beetivaen
'.Elate as cede lose � whiUt woWd have indicated Proposed dmeway since they roof syakms has the
'�•Bev. • were observed in the area. %IOPe moverrterd. 9�vd(resumes or escaryrtprs 40 and 60 pell«u d water a day hom tla gmund and.by ytrmafinnbing,sy g kavern/gof thethe Um that health of the Imes ay maintai maintained °f�•at most the err a F,
a potential
l sfide r The main geologic faMom bat designates bks area as i
2— a paental slide area are the 50 to 60%slopea. Tarpenry Ems-Com.1 ptan.tt Is recon Sol Laoe b ded that tootfirimc,the m icl WI Log. frsrtdrg be placed on the dam hill side d the brldtling eik to mktimze cite
\ brown sr Atypical sod log is b erved for
at the tap d/2'f sheet vrbv a reddish nmdf leaving the site. arnocrX M
_ i sltry berry sip observed i«Irx first 2-12'followed by a kgM gray
A DMwN ar•isloe and ery dense glacial tiN(GtµSA11 wph a 3000 to 4000 psf soil bearing mpaciry Orrapa and Qfhlta lnrpacb.There are no oreite«oRspe
(SYMh YeerArR) and a 5 l0 7%rttasture rnratt. d the primary and reserve draiem as remain d Uteir as long as the lorafim
view to lots far tell of garthis pr,sanf location as Indicated in Ua plan
A Cmaa�acdal.A detailed crps iiecum of the engineering drawing.
�.. above as cross-s-bon A-A. ROPe9ed busing spa s shown
- �Daav'aaprrm Condltbns.The final deveapmerrt ronditiory ere m>sidered
. Slops 5LbUlty,Anaysb.Adetailed slope "
fne 50 to 60°6 oha stability ay for of analysis was part on i
slopes and deterrrdrod that flat factor of sakry agawt sliding was Locadon of the DmknU cis.The location of the ck nfields are t«akl«ed setisfaa
1.98 and 1 18 for$alit and dynamo(earthquake)cases.respectively and was incfi='n the drawing to the left as long as the rewmmendati«o are ldlowed n bus
considered satisfaday. gedetllnical engineering report. "2 Elechital i Ff
transformer DmInage Feawns.It is remnvranded that the surface water riff from the
CL$, plow—,"be ducted irty a 6'diemelar blade dwc aghtline bat takes the w V
Septic d—field d�dleWa water an the way dawn to the bottom d the slope and away from dxx t J f N P.,{� +• �,¢a r
Wall.A mmnvkry well is being shared and a located over I W away hen the 4!f 5 �pF ASy�vY �'9 ' l 4 rciv.p",r�
septic dnalnfield as indicated in the drawfrg to the left d this page. C 'r Co
V Bsa iart NAIt
Q 0758 E
:? trite
Slope Stability Calculations (at Cross-section A-A)
25'
9(W)
Native Soil
� ls\\p p�aoel rvoi to ---
6p [ scale(NTS)
a�Fot�+,Nl
�Al�=31 deg(60%slope) No(m
1. Compute factor of safety(FS)against slipping-Static Case(Ref: "Geotechnical and Foundation Engineering-
Design and Construction", by Rebert W Day, 1999, page 10,28
FS=Resisting force/Driving force
=[c'L+K x Tan(phi')]/[W x sin(alpha)]
=[c'L+(W x cos(alpha)-u x L)tan(phi')]/[W x sin(alpha)]
where: FS=Factor of Safety against sliding(dimensionless parameter)
c'=drained shear strength of the slide plane(c'—300 psf for dense light gray glacial till
phi'=angle of internal friction for dense light gray glacial till—41.3 degrees
L=length of the slip plane surface(feet)=60 ft
N=normal force, i.e.,the force acting perpendicular to the slip surface[(N=W x cos(alpha)]
W=total weight of the failure wedge(i.e.,W=gamma times the area of the wedge), Ibs
for a unit length of slope=(133 pcf)(60 ft x 17 ft)/2=67,800 lbs=67.8 kips
u=average pore water pressure along the slip surface(psf)=0 psf for glacial till
alpha=slip surface inclination(degrees)=31 degrees
FS={(.30 x 60)+[67.8 x cos(31)-(.0 x 60)]tan(41.3))/[67.8 sin(31)]=(18.0+51.1)/34.9=1.98>1.5 OKAY
2. Compute factor of safety against slipping for the Dynamic(seismic)Case, (Ref: Robert W Day, page 10.64)
seismic factor=b=.3(equivalent to 0.3 g's of ground acceleration)
FS=[c'L+(W x cos(alpha)-b x W x sin(alpha)-u x L)x tan(phi')]/[W x sin(alpha)+b x W x cos(alpha)]
={(.30x60)+[(67.8x cos(31)-.3x67.8xsin(31)-.0x60)]tan(41.3))/[67.8xsin(31)+(0.3x67.8xcos(31)]
=[18.0+(58.1 -10.5-0.0)x.88]/(34.9+17.4) = 59.9/52.3=1.15>1.0 OKAY
i
Slope Stablltty Analysis for property located
at 230 E. Baker Court, Belfair, WA 98528
(Parcel# 1220 7759 0072)
Prepared for. Johsua Ferreira i
14120-49th Ave CL NW !
Gig Harbor,WA 98332
i
Prepared by: Morta Engineering&Testing,POB 250,Ocean Shores,WA 98569 }
360 289-0958 800 590-N58 360 289-9682 fax Srnorta@,AOL.com !
{
Mardi 21,2007 Analyzed by: SPM I Page 2 of 2