HomeMy WebLinkAboutBLA Three Fingers Letters - BLA Plot / Site Plans - 12/3/1995 -z 1 Z3_ --15-
Morta Engineering & Testing
Date: December 3, 1995
To: Skeets and Sharon Wilson
26214 S.E. 252°d St.
Ravensdale,WA. 98051
(206)432-0305 Res.
From: Steven P. Morta, P.E. rjJ �l Z
P.O. Box 250 Z
Ocean Shores,Wa. 98569
(360) 289-0958 Bus/Fax.
Subject: Geotechnical Engineering Assessment of Lots 1,2,3 and 4 Located at the
West End of the Second Finger of the Three Finger Subdivision in Mason
County,Washington (Case No: SEP95-0250 Three Fingers, E1161 Wilson
Way, Grapeview)
Introduction
On December 1, 1995, Steven P. Morta P.E., of Morta Engineering and Testing inspected the
above site to perform a geotechn ical engineering assessment of Lots 1 through 4. A site vicinity
map has been included in the appendix along with a detailed plat map of the 4 Lots. The area was
inspected in the middle of the day after several days of continuous rains. This then was an
excellent opportunity to inspect the site for erosion and any potential landslide conditions.
Description of the Site
Partial clearing of the area has taken place in preparation for potential building sites on each of the
lots. There are a few old growth stands of timber approximately 200 to 250 years old with some
scattered stands of 8 to 12" diameter Madrona trees. As shown on the plat map the lots are
somewhat pie shaped with a cul de sac located on the northeast corner of the plat map. This cul de
sac is located 80 to 90 feet above sea level. From here the ground slopes 20 to 25 %toward the
west-southwest direction approximately 400 feet on Lots 1 and2 and slopes 25 to 35 %toward the
south-southwest direction on Lots 3 and 4 approximately 300 feet.
Soil Type below the Surface
An examination of existing cuts on the side of the slope indicates that there's 4 to 5 feet layer of
loamy gravel with silt followed by a hardpan layer of compacted clayey silt with gravel. In a few
isolated spots there was some minor soft spots due to saturated silt and clay but was not enough to
affect the stability of the site.
Slope Stability Assessment
If there were any longterm slope movement this would manifest itself with trees having curved tree
trunks commonly known as "pistol grip" trunks because of their shape. No curved tree trunks
were seen in the area. After carefully walking the area there was nothing to indicate that the
ground is moving or has moved in the past such as fissures in the ground or differential ground
movement. After the recent heavy rains there was only slight soil erosion with no noticeable
landslides taking place. Along some areas of the slope such as on the west end of Lot 1 and the
south end of Lot 4 some bulldozing has taken place to provide access to the lower areas of the
property. These areas resisted erosion and landslides after the heavy rains. However, it is
recommended that these areas be consolidated with a vibratory compactor.
Soil Erosion Control
Areas near the cul de sac have been seeded with grass for soil erosion control and aesthetic
purposes. Grass seeding on Lots 1 and 2 have helped to provide some ground cover to reduce soil
erosion. Minor channeling of water was observed in some areas but for the most part the grass
was taking root and holding the soil inplace as intended.
On the north boundary line of Lot 1 water was seen traveling down the north side of the new
access road toward the sound. To reduce the effect of erosion 6 to 10 inch in diameter smooth
cobbles were placed in the small stream bed to slow down the velocity of the water. Due to the
impermeability and consolidation of the soil the water was essentially flowing over the surface with
little to no erosion. At the time of the observation there was little to no siltation of the stream.
On the east boundary of Lot 4 along a new access road a similar small stream of water was
observed flowing down the slope ending in a 7 foot drop into the sound. It is recommended here
that the road be sloped so that surface water runoff will flow directly into this channel rather than
flowing across an unprotected section of the slope face. In addition this channel should be lined
with rockery or with a perforated 6 inch diameter flexible drain pipe to help slow the flow as it is
traveling toward the sound and thereby reducing sedimentation. Prior to the water reaching the
marine bank, the water needs to be channeled into a minimum 8 inch diameter flexible tightline that
runs over the edge of the bank and onto a concrete splash plate below before entering the sound.
The objective here is to minimize erosion of the marine bluff and at the same time provide adequate
drainage of the area.
It is planned that the sanitary sewer will be pumped up hill away from the area eliminating the need
for drain fields on the slopes which reduces the likelihood of slope failure due to excessive water.
It is important that existing vegetation in the area be preserved as much as practically possible to
help hold the soil in place. Any bare areas other than where the building pad is going to be
constructed should be seeded with indigenous grasses that thrive in a cool, damp marine
environment. To provide additional soil erosion protection ground cover vegetation should be
planted to supplement the natural growth in the area.
Minimum Setback from Marine Bluffs
Along the south sides of Lots 2,3 and 4 exists a marine bluff that varies in height from 7 to 80 feet
high. The 1-to-1 setback rule applies in this case, i.e., the setback from the edge of the bluff is
defined as the height of the bluff For example, if the height of the bluff is 50 feet then the set back
at that point has to be a minimum of 50 feet. At the time of the onsite inspection access to the base
of the bluff was not possible due to high tide conditions. The primary purpose of observing the
base of the bluff was to determine the amount of undermining, if any, is present. A new wooden
stairway leading to the base of an 8 foot high bluff showed that the base consisted of a highly
compacted clayey silt with gravel hardpan with a 3 foot wide dense gravely layer. Little to no bank
erosion was observed.
Sundecks, uncovered porches and steps may be constructed within the setback zone as long as the
structure is no more than 30 inches high not counting railings used for safety reasons.
Allowable Soil Bearing Pressure
Due to the gravely content of the soil and the known hardpan 4 to 5 feet below the surface the
recommended maximum allowable soil bearing pressure is 2000 Ibs/sq-ft. For Lots 1 and 2 where
the bluff is a minimum the concrete foundation wall on the water side should be at least 4 feet
below the surface, if the home is built on the side of the slope. This will provide adequate support
for the home. Prior to the concrete footing pour the soil needs to be compacted to 95% of
maximum density per the latest moisture-density specifications of ASTM D 1557. This means if
the soil is too wet to be compacted then it will either need to be dried out or if this is impractical
then a foot of material will need to excavated out and replaced with suitable structural fill material
and consolidated to 95% compaction. A geotechnical engineer will need to inspect the
consolidation of the soil to ensure that it meets the 95% compaction prior to pouring of any
concrete.
Conclusions and Recommendations
The geotechnical inspection of Lots 1 through 4 was performed after several days of rains with no
indications of ground fissures or slope failures. As long as the surface water runoff and ground
water is directed into properly prepared channels as described above the likelihood of slope
instability is minimized. In addition compaction under the concrete foundations is essential in
maintaining stability.
A 4 to 5 foot layer of compacted sandy gravel with silt covers the area with hardpan underneath.
This provides a relatively stable site for residential construction. As long as the recommendations
arc followed in this geotechnical engineering report there should be very little to no slope
instabilities.
If you have any questions regarding this report do not hesitate to call me at(360) 289-0958.
� l P. AID Respectfully Submitted
wp� W Morta Engineering and Testing,
30758 3��1' Steven P. Morta, P.E.
FG7
�31 Professional Gcoteclm►cal Engineer and Owner
JDNAL��V
CDORES.t/14 7
LAW OFFICES OF
LUNDGAARD & AITKEN
ROBERT E. LUNDGAARD 2400 BRISTOL COURT S.W. TELEPHONE
H. JOHN AITKEN SUITE B AREA CODE 206
943-8440
OLYMPIA, WASHINGTON 98502
August 22, 1989
D N � M
Grace Miller U
Planner
Mason County Department AUG ��!
of General Services 1989
P.O. Box 186 GENE
Shelton, Wa 98584 P,qL SEF?VICS
Re: Stanley Closson - Track III of Stadium Beach
Our File No. 16341
Dear Ms. Miller:
The survey of the above property has now been completed and a
boundary line adjustment agreement is being prepared. The
neighbors to the Closson property, Mr. and Mrs. Belisle, have
verbally agreed to sign the boundary line agreement on condition
that Mr. and Mrs. Closson construct a retaining wall satisfactory
to Mason County. My clients are willing to construct such a
retaining wall.
Wayne Krause of the Mason County Building Department has
indicated that he cannot draw up the specifications for the
retaining wall until the new boundary line has been marked on the
property. That line has now been marked on the property and I
have contacted Mr. Krause to request that he draw up the
specifications.
As soon as the new boundary line adjustment agreement can be
signed by all parties, and the specifications for the retaining
wall obtained from the building department, my clients will
immediately arrange for the construction of the wall.
It is our sincere hope that with the progress that is being made
that your department will defer issuing any citation.
Very truly yours,
LUNDGAARD & AITKEN
— - le-'-;�-'ozeode 1***'
OBERT E. L AARD /%
Attorney at Law
REL:smj
cc: Client
TO: FILE
TELEPHONE CALL BETWEEN MR.BELISLE AND GRACE MILLER
August 8, 1989
Mr. Belisle called to inform the County of his position at this
time in reference to the Closson property. The Closson ' s lawyer,
Bob Lungard , had a survey crew out on Saturday, August 5, 1989.
Name - Ace survey out of Gig Harbor. They based their survey find
on the Lovitt survey of the bottom lot. The discrepancy between the
Lovitt survey and the Holman survey of Mr. Belisle ' s lot was 2' .
This determined that Mr. Belisle' s survey showed he had two more
feet because of his survey. The Clossons had claimed Mr. Belisle
had taken 7 ' of their property with his survey. Now with the survey
find completed , it is closer to 2' and only on the upper- portion
of the property.
(i"gwu t 7, 1989. Bob Lungard , the Closson ' s lawyer, called Mr .
Belisle. Mr . Belisle told him that he would give up 1 ' 3" of his
property( 1/2 way up and to the top of the lot ) if the Clossons will
retain the bank with a proper bulkhead . That 1 ' 3" which he is
willing to bargain over is a split discrepancy( half of ) what the
survey found and what he is willing to give up in order to have
the bank repaired with a retaining wall .
Grace Miller ,Planner
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December 18, 1995
To: Jerry Hauth/Alan Tahja
From: Randy Neff
RE: Geo-tech assessment for the Three Fingers Short Plat
Hi Guys:
I am submitting to you a geo-tech assessment for the Three
Fingers Group. Please review and comment on this assessment.
j
for all the help.
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LAW OFFICES OF
LUNDGAARD & AITKEN
ROBERT E. LUNDGAARD 2400 BRISTOL COURT S.W. TELEPHONE
H. JOHN AITKEN SUITE B AREA CODE 206
943-8440
OLYMPIA, WASHINGTON 98502
September 13, 1989
Roger BeLisle
c/o Marc Wagner
ACE
P.O. Box 2136
Gig Harbor, Wa 98335
Re: Closson/BeLisle Boundary Line Dispute
Our File No. 16341
Dear Mr. BeLisle:
Marc Wagner called and indicated that you wanted a letter from me
confirming the boundary line agreement with my clients Stanley
Closson and Clara Wood.
My clients are agreeable to a boundary line revision of the
common boundary line between your respective lots as follows:
Commencing at the SW corner Sec. 13, T21N, R2W WM.
Thence NO2° 04 ' 30" E 5261 . 97 feet to the NW corner
Sec. 13, T21N, R2W WM. Thence S. 440 16 ' 05" E 5975 . 86
feet to a number 5 rebar set by Daniel F. Holman to
mark the Northeast corner of lot 4 of Stadium Beach
tract, which is the true point of beginning. Thence
S. 02 34 ' 09" W 424. 63 feet to a 1 1/4" threaded bolt
with 2 3/8th" nut being the terminus of this boundary
line revision. Said line being a revision of the
Northerly 424. 63 ' of lots 3 and 4 of the unrecorded
plat of Stadium Beach.
My clients will be responsible for the cost of filing the
boundary line adjustment and the placing of four points along the
line from Holman' s pin on one end to the 1/4" threaded bolt at
the other end of the property line. My clients are also anxious
to construct the retaining wall to standards acceptable to Mason
County. Mason County will not issue a building permit for that
work until the boundary line adjustment application has been on
file. Normally, Mason County would not process a building permit
until the boundary adjustment had been completed. It could take
six to eight weeks to get approval of the boundary line
Roger Belisle
September 13, 1989
Page 2
adjustment, so the county will attempt to issue the building
permit while the boundary line adjustment is being processed.
This will give us an opportunity to complete the work within the
90 day period that you requested.
It is my understanding that you will sign the boundary line
adjustment upon receipt of this letter.
If there are any other matters that have not been covered, please
do not hesitate to contact me or have an attorney contact me.
Very truly yours,
LUNDGAARD & AITKEN
7
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ROBERT E. LUND RD
Attorney at L
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