HomeMy WebLinkAboutGeoTech Assessment for BLD2004-00661 - GEO Geological Review - 5/14/2004 �pN STATF 0
C MASON COUNTY
A° un PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
j - 2 Shelton,Washington 98584
1864 DATE: May 10, 2004
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Grace Miller, DCD - Planner
FROM: Alan A. Tahja, P/W - Co. Hydr. Engr. WO#PLG-04
SUBJ: Geo-Tech Assessment Review NAME: Jenson SFR 64 6300 Grapeview Loop
BLD2004-00661
Grace,
The geotechnical assessment prepared for the proposed Todd Jenson Single Family Residence
(SFR)to be constructed near the 6300 block of the Grapeview Loop Road,has been received and
reviewed by Public Works.
The report appears to satisfactorily address County requirements for geotechnical assessments.
The assessment's author indicates that, in his opinion,the proposed development of the property
will not cause stability problems for either the subject property or neighboring properties, and
that a more detailed investigation(report)is not warranted. From the contents of the report, I
recommend accepting the report as satisfying the County's requirement(s)for stability
investigation and geotechnical reporting. Recommendations contained in the assessment should
be incorporated into the site's development and made conditions for permit issuance.
Adequate erosion and sediment control features need to be implemented during land disturbing
activities to protect neighboring properties and State waters from adverse stormwater runoff
impacts. The migration or release of silty water or mud from the applicant's property will be
considered a violation of County and State water quality protection regulations.
In summary,the geotechnical assessment appears acceptable, and the proposed residential
development of the property should be allowed to proceed, subject to the engineer's
recommendations.
Please feel free to contact me at County extension 461 if you have any questions regarding these
comments, or if you feel any features need further discussion or attention.
S'ncerely,
Z
Alan A. Tahj
File: H: \WP\GEO\Reviews\Jenson.doc
WORK ORDER - PUBLIC WORKS DEPT.,
(A) Date: Q : Td ears Work Order
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COST ESTIMATE _
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PLANNING
Geotechnical Assessment
6300 Block of Grapeview Loop Road
Parcel #122323100060
Mason County,WA
Prepared for
Todd Jenson
Auburn, WA
by
Geotechnical Testing Laboratory
Olympia, Washington
April 23, 2004
GEOTECHNICAL TESTING LABORATORY
TODD JENSON
30840 49TH COURT SOUTH
AUBURN,WA 98001
RE: GEOLOGICAL ASSESSMENT
6300 BLOCK OF GRAPEVIEW LOOP ROAD
PARCEL 122323100060
N47021.216' W 122°50.077'
PURPOSE
The objectives of the geological assessment are to assess the surface and subsurface conditions
prevalent at the subject site according to Mason County Ordinance 17.01.100.E4. A single-family
residence with a septic system is proposed.
74.
r. t..._ ; "..
GEOLOGIC CONDITIONS
The proposed single-family residence will be located at
approximately 6300 Grapeview Loop Road in Mason County,
Washington. The site is located approximately 2.0 miles south of
Allyn, Washington. The location of the site is shown relative to
the surrounding area on the Vicinity Map, shown on Figure 1.
Slope angles for the proposed building site are from 10 percent to
20 percent. The lot is gently sloping
(approximately 18 percent) with southeastern exposure. The site
is bounded by undeveloped forestland on the north. A residence is
to the south. Eberhart's Cove bounds the site on the southeast.
Grapeview Loop Road borders the site parcel on the west. The lot
is mostly vegetated with vegetation common to the Northwest.
No surface water was observed at the site during the site
reconnaissance. Rapid stream incision was not discerned at the
site. No deep-seated instability was observed at or around the site. '
10011 Blomberg Street SW, Olympia,WA 98512 1
Phone#: (360) 7544612 Fax#: (360)7544848
GEOTECHNICAL TESTING LABORATORY
The Soil Survey of Mason County, USDA Soil Conservation
Service (1960) has mapped the site soils as an Alderwood
gravelly sandy loam, 5 to 15 percent slopes (Ab). The
Alderwood soils typically formed from glacial advance outwash.
They are described as having good natural surface drainage.
Typically, there is no occurrence of a high water table. Internal
drainage is described as medium. An erosion hazard may exist
if the vegetation is removed; otherwise, the soil has a low
erosion hazard in its present condition. Cementation is usually
present.
The soils at the site are mapped as Alderwood gravelly sandy loam (Ab). This site does not meet the
technical criteria of an erosion hazard area.
The Coastal Zone Atlas, Volume 9, Mason County(MA-I2) maps the site as Vashon glacial till (Q,t).
The till is a tough, dense material of low permeability. It provides excellent foundation support. The
site slope stability is described as"stable" at the building site and "intermediate" along the coast.
M
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GROUNDWATER CONDITIONS
No groundwater seepage was observed at the site. No wetland vegetation was observed at the site.
Depth to static groundwater is approximately 32 to 40 feet below the ground surface. A well log for
the area follows this report.
. 3 -
RRO
w4 _
10011 Blomberg Street SW, Olympia,WA 98512 2
Phone#: (360) 754-4612 Fax#: (360)754-4848
GEOTECHNICAL TESTING LABORATORY
DEPTH TO COMPETENT SOIL
r
Typically, dense glacial till is found from 24
inches to over 48 inches below the ground
surface. The glacial till extends to an
approximate depth of 40 feet.
PAST SLOPE INSTABILITY
Onsite trees were found straight and vertical. 1 '
Evidence of landslide activity was observed *�
along the coastal bluff. The slump is due to a
,
tree toppling.
HISTORY OF LANDSLIDE ACTIVITY
The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the site
area as Class 1. Class 1 is expressed as,
Areas believed to be stable. Slopes generally less than 15 percent, but may be
greater locally in areas too small to be shown at the map scale. Largely comprises
rolling uplands underlain by very stable material such as young glacial till, mantled
in places by a thin layer of sandy gravel or other permeable material, also includes
flood plains, deltas, alluvial fans, and some beach deposits. Class I areas
immediately adjacent to steep slopes of class 3 areas may be threatened by
potential landsliding. Normal, proper engineering practices generally are
adequate to insure stability in these areas.
POTENTIAL FOR LANDSLIDE ACTIVITY
This site has no indication or record of deep-seated instability. Even though the coastal slope exceeds
100 percent, the potential for landslide activity is not a concern for the proposed building location.
C
ems,. p '! T 6 _ <l►► 04` J
i
4,
10011 Blomberg Street SW, Olympia,WA 98512 3
Phone#: (360) 7544612 Fax#: (360)7544848
GEOTECHNICAL TESTING LABORATORY
RECOMMENDATIONS
There is no evidence of soil erosion
anywhere on the site to suggest that the
site should be included in the Erosion
Hazard Area designation. Site conditions
for the proposed development do not
warrant a more comprehensive '
Geotechnical Report. We recommend no
further action is needed unless areas of
concern are unearthed during
construction.
9
If there are any changes in the loads,
grades, locations, configurations or types
of facilities to be constructed, the
conclusions and recommendations presented in this report may not be fully applicable. If such
changes are made, we should be given the opportunity to review our recommendations and provide
written modifications or verifications, as appropriate.
Respectfully,
,j Was GEOTECHNICAL TESTING LABORATORY
9�0
�� E►� ,oaoaoow Harold Parks, L.G., L.E.G.
827 ` Senior Engineering Geologist
'sed Geo�o
H.'_RCLD PARKS
A�
10011 Blomberg Street SW, Olympia,WA 98512 4
Phone#: (360) 754-4612 Fax#: (360)754-4848
GEOTECBNICAL TESTING LABORATORY
VICINITY MAP
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10011 Blomberg Street SW, Olympia, WA 98512
Phone#:(360)754-4612 Fax#:(360)754-4848
Tito Or")and First COPY With Appircatioa Aft. ..........
sew r ntr mcol ogya c�pr WATER WELL REPORT
ZAfrd t opy-Driner s Dour BrAi! OF WASEDFO DN Permit lNo. ....
(1) OWNER:- x...... ...... ... .P.. 4. Pt.......
_...... {ti$.9$Q04
(2) LOCATION OF WELL.: cou ty....._M4.3-Q0.__......_. ................................. ._._........�
1!ear nj and dfatanoe from sectim or subdivision corner Guylt Lnt 3- Abutting
(3) PROPOSED US$ Domestic 0 Industrial ❑ llanlmpal❑ (10 WE+ LOG:
hriratlop ❑ rest Wen a Other ❑ wsc+w�bW�ncam dtarmw alas of,natarist a",tncaar,and
after ft- ofaSMSJ►+Weidisatawm-*a"for�each dat morw tore material matbw
(4) TYPE OF WORK: iowner's number oe D n°f well
) ••---._. ll[A?1�RIAI. IRON TO
New well 01 Method:Dos 0 Bond 0 Tn pnn-i 1--- 0 1—
Da.vened ❑ cow O Drivels0
Re imadhimad❑ ftomry O Jetmd O HardpAn
(5) DIMENSIONS: Diameter of well �lemur �.
Drilled,......93 -_A. Depth at camplsted well 93 ••
(6) CONSTRUCTION DETAIIAC -
Clnsin6 installed:_6"_•Dmos.In,—Q n.ID_9 3 9L
Thread"p N_ _••Diem.farm. 9L to—&
Welded •Omni.free►.__. ._m b_ fx.
Perfasationm Yr❑ mole
Type of perforator arai
SIZX of ptrforatiom --_-_. in.by fps
_•---.._ Perforations aces,_ .. a.to_.._. _ _ft.
•---__sees.._ ptrtoradOOa Garb--.. _.!t.b 9L
peaftraucas beam ___ _it.tf _. f t.
Screens: Yes❑ NOW
maentacbmn's ftesb<
Madel 1fo
Diem_ Sot dw__-_--- ham_..._ .ft.10____9L
Diam. _____sees Stet Misr
Gravel packed: Yes❑ No at size ce sraval: -----
Gravel placed fiorb _...— ft.to
Surface seal: Yss(3 146 0 TO vim dery -18 9L -—
msterial veld to
Did am strata "amain mwablf —at"1 Yes❑ I%Q
T"m as waterl—. —Depth of strata— _
Method of wallas atram aif:—.—... —
(7) PUMP: ----
"s: ..—_- _.._.HP---
FEB 19OU
(9) WATER I"MS:
static ler.I ._.... 3 4_....._._.__.... ft bibs top ee well Daa 1-22-80 p�:,t•�_.!' t.'
Artedan press".--^. u: per aaaare meh ow iy-4;•-t ''t'• .
Artestm water is mntroxLed by—
(9) Will, TmTS. Iowa wa"belosw s'mme"t�Tt.a to waft started_ Jan 15 ,„_ 80 ces„yki—Jan 19 ly_�.0
Was a pump test medal Yee 0 No a V yarn by —
Yfeid• tSal.ymin.with ft_drawdown alter fats. WELT. Den. AZIS STATEMENT`
. Tbfs well was drilled under my Jurisdiction and this report m
trier to the best ad espy knowledge and belief.
Reeovsq data (time taken as zero when pimp tttrbad Off) (wstar Meat
mea=d from well top to water ltrel) -
Time water Lrvel rime L Water ea a firm,
st ?Mwe W6W Laud xw�iiN..._.Y__....�_.
{F+eao or eoepoiaUomtiobl (Type or prinU
Address—
P.O. Sox 3G, Allyn, _w a._96524
.........
Dow..... of test� -.+.... .....----.-__.........-..........
Bailer test.-1�._.y1/pds.with leer..ss.drawdsw drm (Won Ocular►
Arse.lan now._ _____ _.._ =. amw—
Temper t tr.of watw-._.._.._Wes a dmnN I a.a ell a.eat V t o No 0 [ieeose No_ _..- �.._ .._..._..._._Date........J a n,e_N--• I9.9 0.
MR ADDITIONAL ORLTA IF NRC1g511ARY)
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ECY 050-1-20