HomeMy WebLinkAboutNotice of Hazardous Site Conditions - PLN General - 3/26/2014 cOONrp MASON COUNTY (360)427-9670 Shelton ext.352
DEPARTMENT OF COMMUNITY DEVELOPMENT (360) 275-4467 Belfair ext. 352
BUILDING•PLANNING•FIRE MARSHAL (360)482-5269 Elma ext. 352
lxsa Mason County Bldg. III, 426 West Cedar Street
PO Box 279, Shelton, WA 98584 www.co.mason.wa.us
March 26, 2014
Michael and Kathy Eacrett
80 E Buckingham Lane
Grapeview WA 98546
NOTICE OF HAZARDOUS SITE CONDITIONS
PARCEL NUMBER: 12108-11-00010
SITE ADDRESS: 80 E Buckingham Ln., Grapeview
Dear Mr. and Mrs. Eacrett,
On March 19, 2014, Mason County staff observed a threatened patio and recent collapsed drainpipe,
tree roots, and eroding slope materials fallen to the concrete bulkhead that are potential violations of
the Mason County Resource Ordinance, Landslide Hazard Areas 17.01.100. Corrective measures to
address these issues will require the preparation of a geologic study by a qualified professional and
submittal of permits for work to stabilize the area and prevent further damage to nearby properties.
A Mason Environmental Permit (MEP) with a geotechnical report is required to be submitted prior to
conducting any land clearing activities or stabilization of slopes exceeding 40 percent. A qualified
person, as defined in the Mason County Resource Ordinance, must prepare the geotechnical report for
the properties, provide the study to the landowner, who then submits the document and permit
applications to Mason County.
You will now need to submit the following:
A. An application for the MEP can be found at our Home Page address:
http://www.co.mason.wa.us/forms/Community_Dev/environmental_permit.pdf
B. Applicable code provisions from the Mason County Resource Ordinance Pg. 49 to 58:
http://www.co.mason.wa.us/code/Community_Dev/resource_Ord_j u ne_2009.pdf
C. Fees: Geotechnical Report Review - $255.00
Mason Environmental Permit (MEP) - $380.00
Planning Inspection fee- $255.00
I anticipate receiving your response to this letter about the deteriorating site conditions
at the subject property site; and the submittal of the Mason Environmental Permit,
Geotechnical Report, site plans, and necessary fees by April 24 to May 1, 2014.
If you have questions regarding the compliance requirements, please contact me at(360) 427-9670
ext 365, or by mail at P.O. Box 279, Shelton WA 98584. Thank you for anticipated cooperation.
Sincerely,
AIlan Borden
Senior Planner
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April 7,2014
Mike Eacren
80 E Buckingham sane
Grapeview,Washington 99546
RE: Geotechnical Addendum for Property Located at 80 E Buckingham Lane,Grapeview,
Washington—Project Number 0977
Dear Mr.Eacrett,
Envirotech Engineering(Envirotech)completed a site visit,field inspection and conclusions for the single
family residential property at the referenced location. Specifically, this addendum is in response to a
recent landslide that occurred on the shoreline bluff that encompasses both the referenced property and
the neighboring property to the east.
The most recent geotechnical site inspection was conducted on April 3, 2014 in order to observe the
landslide with relation to the development. The original geotechnical report, dated October 5, 2009, was
prepared by Envirotech. Information pertaining to the project was provided by the property owners.
Information collected from site observations,and previous field testing was completed by Michael Staten.
with Envirotech.
The recent earth movement is a small-scale, shallow translational debris landslide typical in this region,
especially along steep shoreline bluffs. The underlying very dense glacial till soils, as observed in the
landslide scarp,mitigate potential large deep-seated landslides.
Per our original geotechnical report, unstable slopes were delineated along the face of the shoreline bank
and extend 10 feet from the top of bank. This is a conservative estimate, and the unstable upslope area is
more likely to be in the range of 2 feet to 6 feet from the crest of the bluff'
Landslides are generally a result of a complicated interaction between one or a combination of gravity,
water and earthquakes_ Secondarily, Iandslides may be propagated or mitigated by soil characteristics,
vegetation,and man-made disturbances.
Envirotech concludes that earth movement along the shoreline bank is an existing inherent hazard to both
properties, and could occur at anytime for a distance of up to 10 feet behind the top of slope. Due to the
very steep conditions, gravity alone and seimic activity have both been shown in our slope stability
analysis to delineate the bank as potentially unstable. However, there is no doubt that the induction of
water to the slope decreases the factor of safety to an already unstable bank.
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Cell: 360-689-6045
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Currently, the scarred area of the recent landslide is the most stable portion of the bank because the
overburden soils have been removed leaving behind a more stable geology. The areas adjacent to both
sides of the scar have a higher propensity to unravel. Evidence of old landslides are present on and near
the subject property, sections of the bluff along both properties may slide in the future, and are unrelated
to the most recent landslide.
We conclude that our recommendations provided in our original report concerning future house and
staircase development have not been affected due to the recent landslide. Envirotech should be consulted
if mitigation is desired_ Complete mitigation to provide a factor of safety deemed safe would be
expensive_ This includes pile and lagging walls or removal of the upper bank in order to create a gentle
slope_ Economical enhancements such as drainage mitigation and vegetation management may be
performed to increase the factor of safety,but cannot guarantee that future landslides will not occur_
If you have any questions or need any further assistance concerning this letter, please contact Michael
Staten at 360-275-9374_
Sincerely,
Envirotech Engineering
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