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COBALT Cobalt Geosciences,LLC
GEOSCIE P.O.Box82243
Kenmore,Washington 98o28
May 11,2021
Clyde Corbin
Cllvdecorbin68(&comcast.net
RE: Limited Geologic Evaluation
Proposed Residence
Parcel No.322127500110
Mason County,Washington
In accordance with your authorization, Cobalt Geosciences, LLC has prepared this letter to
discuss geologic hazards and development suitability of the referenced property.
Project and Site Description
The site is located at 1o5i NE Tahuya River Road in Mason County, Washington. The site
consists of one irregularly shaped parcel(No.322127500110)with a total area of 5.23 acres.
The site is undeveloped (excerpt for a narrow access road) and vegetated with grasses, bushes,
blackberry vines,ferns,ivy,and variable diameter trees.
The site slopes downward from west to east at variable magnitudes with total relief of about 110
feet. The site is nearly bisected in the east-west direction by a steep slope area. The slope has
relief of about 70 feet and magnitudes of about 40 to 8o percent (in most areas). The areas east
and west of the steep slope have magnitudes of about o to 30 percent and local relief of 20 feet
each.
The site is bordered to the north and south by residential parcels.To the west by NE Tahuya River
Road,and to the east by the Tahuya River and other parcels.
The proposed construction includes a W. residence and driveway located in the southwest
portion of the property. Site grading may include cuis on to 7 feet or more if a daylight basement
is proposed.
Area Geology
The Geologic Map of the Lilliwaup Ouadranglg,indicates that the site is near the contacts between
ice Contact Deposits and Alluvium.
Alluvium is located in the vicinity and channel of the adjacent river (east of the steep slope) and
consists of coarse gravels, sands, and variable layers/thicknesses of silt, clay, and organic debris.
These materials typically include loose heterogenous mixtures and layer of other soil materials
deposited in river or stream channels.
The Ice Contact Deposits can include relatively dense sands and gravels as well as till-like diamict.
In this area,the soils range mostly from cobbly gravels and till-like materials. These soils would
become relatively dense below a weathered zone.
www.cobaltgeo.com (2o6)331-1097
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August 3,2022 -
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Limited Geologic Evaluation
Closure
The information presented herein is based upon professional interpretation utilizing standard
practices and a degree of conservatism deemed proper for this project. We emphasize that this
report is valid for this project as outlined above and for the current site conditions and should not
be used for any other site.
Sincerely,
Cobalt Geosciences,LLC
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8/1/2022
Phil Haberman,PE,LG,LEG
Principal
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Attachments
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Cobalt Geosciences,LLC
Proposed Residence LIDAR P.O.Box 82243
♦` Parcel No. 2212 00110 IMAGE Kenmore,WA 98028
• • 3 75 (2o6)331-1097
7GEOSC I EN CES Mason County,Washington FIGURE 2 www.cowtgeo.com
cobaltgeoOgmail.com