HomeMy WebLinkAboutBLD2011-00037 Geotechnical Report • •
Jan.23,2012
Page 1 of 3
Morta Engineering & Testing, PLLC
To: Loren and Diane Falk
2682 Dosewallips Rd
$�Irror)Heedspe4, WA 98304 g8'330
(360)770-7701 cell,throgmorton475Cgmail.com
Subject: FINAL GEOTECHNICAL ENGINEERING REPORT for the Property Located at
2682 Dosewallips Road, Brinnon, WA 98320 (Permit #BLD11-00037, Parcel
#602285001, Permit# MLA-09-00039, Knudsen Plat Large Lot#1, T26N,RO2W,
Sec 28,W.M.)
Ref: "Geotechnical Engineering Report for 2682 Dosewallips Rd, Brinnon, WA"
Prepared by Morta Engineering and Testing,PPLC,dated Feb. 12,2010
Introduction
On Monday, January 23, 2012 this geotechnical engineer that prepared the report as referenced
above inspected the site at the above address. This engineering report summarizes the results of
this inspection. Digital color photographs were also taken while onsite for documentation
purposes.
Foundation for the Manufactured Home
This geotechnical engineer used a 3' long x %" diameter steel geoprobe to verify that the
reinforced 4" thick concrete slab was poured on undisturbed native silty glacial till soils as
required on page 2 of 4 item (7) of the referenced geotechnical report above. Prior to the
concrete pour, a 6" layer of granular structural fill was placed over the entire building footprint
and compacted into place followed by a 2" layer of compacted sand for leveling purposes. Four
24" wide concrete runners reinforced with#4 longitudinal rebar was poured inplace underneath
each of the four steel I-beams that supports the 27' x 65' double wide. There were no signs of
foundation settlement such as perimeter CMU block cracking or ground fissures or no sloughing
of soils around the structure and,therefore,the poured foundation was found to be adequate.
Roof Runoff
The four roof downspouts were connected into two infiltration trenches, one trench at each end
of the manufactured home. An overflow PVC pipe was connected on the downhill side of both
infiltration trenches so in case there was heavy extended rainfall, that the overflow would sheet
flow near the top of the slope and, thus, minimize any soil erosion of the slope face. Even after
extended rainfall, there was no evidence of any overflow indicating that the roof runoff was
percolating back into the ground to help recharge the aquifer below. A 3' x 3' x 7' infiltration
1018 E.Wishkah St., Aberdeen,Washington 98520
(360)289-0958 Bus,(360)861-8493 Fax,(800)590-0958 Toll Free
Smortanaol.com
• I
Jan.23,2012
Page 2 of 3
Morta Engineering & Testing, PLLC
trench was also constructed for the 30' x 35' shop building. All constructed infiltration trenches
were considered satisfactory.
Setback of Foundation from North Slope
The required minimum setback from the 70 to 90% north slopes was specified to be 15 feet as
stated on page 1 of 4 in the geotechnical engineering report as referenced above. This engineer
verified that this 15' minimum setback was, indeed,satisfied and in most cases the setback of the
foundation from the 70 to 90%slopes was greater than 15' and more like 25 to 30'.
Septic Drainfield
Originally, the septic drainfield was going to be located between the residence and the north
slope. However, a better location was found between the residence and the south uphill side of
property where a relatively level area was prepared. Four(4) 60' long septic drainfield trenches
were placed in this area and can accommodate a two bedroom home such as the 27' x 65'
manufactured home. This geotechnical engineer determined that the new location was
satisfactory since it was placed much further away from the steep downhill slopes on the north
side of the residence.
Retaining Wall
On page 1 of 4 of the geotechnical engineering report,a 5' high 2 to 3' diameter riprap retaining
wall was called out. During the onsite visit, this geotechnical engineer determined that this
retaining wall was not necessary since the slope was less than 40% and very stable. A steel
pointed geoprobe determined that the native silty glacial till soils were very dense and compacted
and that the likelihood of a slope failure on the south side of the residence was minimal. The
homeowner plans on constructing a drainage ditch at the base of the uphill slope to prevent any
uphill runoff from flowing toward the residence. Even after heavy precipitation, there did not
appear to be any runoff from the south slope since most of the runoff percolated back into the
silty glacial till soils and,thus,reducing the likelihood of any soil erosion.
Bails of straw was spread throughout the uphill southeast slope face to help prevent any soil
erosion and to stabilize the soils to allow natural ground cover vegetation to establish itself
during the upcoming spring and summer months.
3' Diameter HDPE Culvert
This geotechnical engineer inspected both the inlet and outlet ends of the 3' x 20' high density
polyethylene (HDPE) corrugated pipe that was placed underneath the driveway as indicated on
page 1 of 4 of the engineering drawings. Additional 1 to 1-1/2 foot diameter rip-rap was placed
at both ends of the pipe to prevent scouring of the native silty glacial till soils. No soil erosion or
sloughing of the embankment was observed. Also,there was adequate cover over the HDPE pipe
1018 E.Wishkah St., Aberdeen,Washington 98520
(360)289-0958 Bus,(360)861-8493 Fax,(800)590-0958 Toll Free
Smorta@aol.com
f f • •
Jan.23,2012
Page 3 of 3
Morta Engineering & Testing, PLLC
to protect against deformation from heavy traffic. As a result, this engineer considered the
placement of the 3' diameter culvert satisfactory.
Preservation of Trees and Vegetation
As called on page 1 of 4 of the February 12,2007 geotechnical engineering report,the trees and
vegetation that were not located on the immediate building site were preserved to help hold the
silty glacial till soils in place especially during periods of high winds and saturated soil
conditions from extended heavy rainfall.
This engineer observed a couple of trees that had bowed trunks but the remaining trees had near
vertical tree trunks. Typically, bowed trunks indicate that the slopes may be moving downhill
over a long period of time. However, since only a couple of trees were bowed, more than likely
they had been disturbed when they were saplings and just grew this way instead of the ground
moving below them.
Conclusions
It is the conclusion of this geotechnical engineer that after observing the site on Monday,
January 23, 2012 that this engineer's plans and recommendations and addendums were followed
to this engineer's satisfaction. Also, it is to be noted that the 25' x 25' 2-garage as shown on
page i of 4 will be constructed at a later date closer to the residence and will have its own 3' x 3'
x 5' infiltration trench to take care of the roof runoff and would be very similar to the existing
infiltration trenches for the residence and the shop.
If you have any questions regarding this final geotechnical engineering inspection report do not
hesitate to contact this engineer at(360)289-0958 or by e-mail at smorta@aol.com.
Respectfully Submitted, A 2 4 ZUf2
,ASS24VDC/ff/(446 . 1y0
5� •
PwAsy,• 9
Steven P.Morta,P.E. co •
p .p 30758 p 4
I Expires: - 7'-?id/7 I
1018 E.Wishkah St., Aberdeen,Washington 98520
(360)289-0958 Bus,(360)861-8493 Fax,(800)590-0958 Toll Free
Smorta@aol.com
• •
Jan.24,2012
Page 1 of 1
Morta Engineering & Testing, PLLC
To: Loren and Diane Falk
2682 Dosewallips Rd
Heedspert, WA.98332 98'320
(360)770-7701 cell,throgmorton475gmail.com
Subject: FINAL STORMWATER REPORT for the Property Located at 2682 Dosewallips
Road, Brinnon, WA 98320 (Permit#BLD11-00037,Parcel#602285001,Permit#
MLA-09-00039,Knudsen Plat Large Lot#1,T26N,RO2W,Sec 28,W.M.)
Ref: "Geotechnical Engineering Report for 2682 Dosewallips Rd, Brinnon, WA"
Prepared by Morta Engineering and Testing,PPLC,dated Feb. 12,2010
On Monday,January 23,2012 this geotechnical engineer inspected the stormwater facility at the
above location per the geotechnical engineering drawings dated February 12, 2010. All
infiltration trenches for the 25' x 65' manufactured home and the 30' x 35' shop were installed
per the approved engineering drawings. An additional 3' x 3' x 10' infiltration trench filled with
1 to 3" diameter drainrock was constructed for the manufactured home so that there is an
infiltration trench at each end of the residence. The 25' x 25' 2-car garage will be constructed at
a later date and will have its own 3' x 3' x 5' infiltration trench for the roof runoff.
The 3' x 20' I-IDPE culvert that was placed underneath the driveway as indicated on page 1 of 4
of the geotechnical engineering drawings was installed per this engineer's plans and
recommendations. Additional 1 to 1-1/2' diameter rip-rap was placed at both the culvert inlet
and outlet by the owner to prevent scouring of the native dense silty loam granular soils. No soil
erosion or sloughing was observed indicating that the culvert is channeling the unnamed creek in
the proper direction as planned.
At the entrance onto the property off of the Dosewallips Road, additional ditching was required
to ensure that the surface water runoff from the neighboring property to the south was flowing
into the Dosewallips ditch line instead of over the Falk's driveway entrance. This engineer
observed that all surface water flows were now directed into the 24"diameter culvert that directs
this runoff underneath the Dosewallips Road.
Finally, after the site inspections, this geotechnical engineer concluded that the stormwater
system was properly installed per this engineer's recommendations and plans dated August 20,
2007 and revised on February 12,2010.
If you have any questions regarding this final geotechnical engineering inspection report do not
hesitate to contact this engineer at(360)289-0958 or by e-mail at smortana aol.com.
Respectfully Submitted, 1 4p ,t�ti't4ownsi� G JAN 3 0 2012 �
,
Steven P. Morta, P.E. /, T , hi!'
JEFFERSON COUNTY P"/
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DEPT.OF COMMUNITY DE\'EEOPMF"'T 140. .. ��
307588 <1
1018 E. Wish kah St., Aberdeen,Washington 98520 SStONALE�C`
(360)289-0958 Bus,(360)861-8493 Fax,(800)590-0958 Toll Free
Smorta@aol.com
I Expires: l l ..26'4?I