10102 242ND PL SW.PDF10102 242ND PL SW
OEOTECH
CONSULTANTS, INC.
Rick Good
10102 - 242"d Place Southwest
Edmonds, Washington 98020
Subject: Geotechnical Engineering Reconnaissance
Breakfast Nook Underpinning
10102 - 242nd Place Southwest
Edmonds, Washington
Dear Mr. Good:
13256 Northeast 20th Street, Suite 16
Bellevue, Washington 98005
(425) 747-5618 FAX (425) 747-8561
January 6, 2014
JN 14001
via email
The undersigned associate visited the subject site in April 2013. The purpose of this visit was to observe the
existing site conditions, excavate a shallow hand auger holes, and to develop opinions regarding the
settlement of the existing southern breakfast nook and underpinning options. The recommendations and
conclusions presented in this report are professional opinions based on the visual observations made during
our site visit and on previous experience with similar projects. We excavated a shallow hand auger test hole
during our visit, but no deep subsurface explorations were conducted for our work.
• We were provided with three preliminary plan sheets for the proposed remodel/underpinning (Sheets S0.1,
S1.1, and S2.1 by CG Engineering). Based on these plans, we understand that the breakfast nook to the
south of the a modest attic addition with dormers additional story will be added to the existing residence over
the majority of the footprint of the house. The only anticipated excavations will be for any underpinning work
to the residence.
If the scope of the project changes from what we have described above, we should be provided with revised
plans in order to determine if modifications to the recommendations and conclusions of this report are
warranted.
SITE CONDITIONS
The nook is attached to the southern side of the house and the areas around the house and nook are level.
Overall topography slopes gently to the south from the street. The site is developed with a single story, single
family residence. The existing house has a crawlspace. The nook foundation is very shallow -y12 inches. No
obvious settlement in the main house was indicated by our observation of the existing foundation, but the nook
appears to have settled a couple inches in a short span away from its attachment to the main house.
Our understanding of the subsurface conditions at the site is based on the observations made during our
recent site visit and on experience gained from other projects in the site vicinity. During our visit, we
excavated a shallow hand auger test hole on the western side of the nook. The test hole was directly adjacent
to the existing foundation. The hand auger holes was advanced to 4 feet below the existing grade and
revealed loose, slightly silty sand fill over topsoil beneath the existing nook footings. Medium -dense to dense
native sands were encountered at approximately 4 feet.
CONCLUSIONS AND RECOMMENDATIONS
Our explorations at the site found loose fill soils beneath the existing nook foundation levels. Based on the
soil conditions, we would recommend that the nook be underpinned to halt settlement but supporting the nook
building loads by pipe piles driven into the dense native soils at depth beneath the subject site. We offered
overexcavation (concrete plinth) options, but we understand that you prefer the pin pile underpinning.
A 2-inch-diameter pipe pile driven with a minimum 90-pound jackhammer to a final penetration rate of 1 inch
or less for one minute of continuous driving may be assigned an allowable compressive load of 2 tons. Extra-
Rick Good JN 14001
January 6, 2014 Page 2
strong (schedule 80) steel pipe should be used. The site soils should not be highly corrosive. Considering
this, it is our opinion that standard "black" pipe can be used, and corrosion protection, such as galvanizing, is
not necessary for the pipe piles. Subsequent pipe sections should be connected together using threaded or
slip couplers, or by welding. If slip couplers are used, they must fit snugly into the ends of the pipes. This can
require that shims or beads of welding flux be applied to the couplers.
Brackets, pile caps, or grade beams may be used to transmit loads to the piles. A minimum of two piles
should be used in isolated pile caps, in order to prevent eccentric loading on individual piles.
Lateral loads may be resisted by passive earth pressure acting on the vertical, embedded portions of the
foundation. For this condition, the foundation must be either be directly against relatively level, undisturbed
soil or surrounded by level fill. We recommend using a passive earth pressure of 350 pounds per cubic foot
(pcf) for this resistance. If the ground in front of a foundation is loose or sloping, the passive earth pressure
given above will not be appropriate. We recommend a safety factor of at least 1.5 for the foundation's
resistance to lateral loading, when using the above ultimate passive value. Due to their small diameter, the
lateral capacity of vertical pipe piles is negligible.
It is difficult to accurately estimate the length that the piles will need to be driven to achieve the recommended
refusal rate. However, we do recommend that the piles be driven to a minimum embedment of 6 feet below
the existing grade. It is likely that the piles will extend deeper than this minimum length.
There are no slope stability issues at the site with regards to this addition. Cuts for the proposed pile
installation will be less than 4 feet deep and may be made vertically at that depth.
REVIEW OF PLANS
We have completed a general review of the geotechnical aspects of the provided plans and specifications for
the underpinning (Sheets S0.1 through S2.1 by CG Engineering). In our judgment, the plans conform to the
recommendations in this geotechnical engineering report. If all of the recommendations and conditions of the
geotechnical engineering report are satisfied during construction and use of the project, the proposed project
will not increase the potential for soil movement. We acknowledge appointment as Special Inspector for this
piling on this project, and by copy of this letter, request that we be kept informed of the progress of
construction so we are able to make the necessary observations, as required by the Edmonds, in a timely
manner.
ADDITIONAL SERVICES
Geotech Consultants, Inc. shall be retained to provide geotechnical consultation, testing, and observation
services during construction. This is to confirm that subsurface conditions are consistent with those indicated
by our exploration, to evaluate whether earthwork and foundation construction activities comply with the
general intent of the recommendations presented in this report, and to provide suggestions for design
changes in the event subsurface conditions differ from those anticipated prior to the start of construction.
However, our work would not include the supervision or direction of the actual work of the contractor and its
employees or agents. Also, job and site safety, and dimensional measurements, will be the responsibility of
the contractor.
During the construction phase, we will provide geotechnical observation and testing services when requested
by you or your representatives. Please be aware that we can only document site work we actually observe. It
is still the responsibility of your contractor or on -site construction team to verify that our recommendations are
being followed, whether we are present at the site or not.
GEOTECH CONSULTANTS, INC.
=t.
Rick Good
January 6, 2014
LIMITATIONS
JN 14001
Page 3
The analyses, conclusions, and recommendations contained in this report are based on site conditions, as
they existed at the time of our site visit. If the subsurface conditions encountered during construction are
significantly different from those anticipated, we should be advised at once so that we can review these
conditions and reconsider our recommendations where necessary. Unanticipated soil conditions are
commonly encountered on construction sites. Such unexpected conditions frequently require making
additional expenditures to attain a properly constructed project.
This report has been prepared for the exclusive use of Rick Good, and their representatives for specific
application to this project and site. Our recommendations and conclusions are based on the site materials
observed and on previous experience with sites that have similar observed conditions. The conclusions and
recommendations are professional opinions derived in accordance with current standards of practice within
the limited scope of our services. No warranty is expressed or implied.
We trust that this report meets your immediate needs for the proposed development. Please contact us if we
can be of further service.
Respectfully submitted,
GEOTECH CQU%JI-TANTS, INC.
CIS
�
ti
S 01 � �02/06/14
James H. Strange, Jr., P.E.
Associate
JHS/j hs
GEOTECH CONSULTANTS, INC.
10102 242ND
EDMONDS,
OSIER
RICHARD & SHEENA GOOD
10102 242ND PL SW
EDMONDS, WA 98020
425.582.8158
CONSULTANTS
CIVIL/ STRUCTURAL ENgNEER
CG ENGINEERING
250 4TH AVE S, SUITE 200
EDMONDS, WA 98020
425.778.8500 FAX 778.5536
CONTACT: MARCO OREJUELA QUINTANA
LEGAL DESCRIPTION
LOT 22, RICHMOND PARK HOMES, ACCORDING TO THE PLAT THEREOF RECORDED IN VOLUME 13 OF
PLATS; PAGE 34, RECORDS OF SNOHOMISH COUNTY, WASHINGTON. SITUATE IN THE COUNTY OF
SNOHOMISH, STATE OF WASHINGTON.
PARCEL NUMBER
00554900002200
TOTAL LOT AREA = 9,583 SQFT
EX. BUILDING FOOTPRINT = 1,180 SQFT
PROPOSED BUILDING FOOTPRINT = NOT TO CHANGE
TOTAL IMPERVIOUS SURFACE = NOT TO CHANGE
SCOPE OF WORK
STABILIZE FOUNDATION WITH PIPE PILES
cna - 2 Corner.& Flag__N
Setbacks fired Actual
Front
Sides e/
Rear
Other
Ifeight
APPROVED AS NOTED
NGINEERING
Q Date:
J�) o Vlt,v \ M�\111�v4Sg
LV`t-mtt,
OWNER/CONTRACTOR IS RESPONSIBLE FOR
EROSION CONTROL AND DRAINAGE
i-.Ioplicant shall'repair/replace al!. damage to :A .
utilities or frontage improvements in City
right-of-way per City :standards that is caueed
i or occur, during, the permitted project.
t'o
a
PROJECT SITE
i this permn c approval Prmce$s mall be
irlotli .. allowang ,or percnittmg the
interP cu�Tently exiatin ille�
maintenance ;`f anye structure the
nonconfornung or unpe-initted building
nditlon which is outside the acoP
or site lication, regardl� °f , "ether such e
unit aPp structure or
pe ovum
building,cture °rSunchd but d ng,
gI pIan or. dravo:=1g• ��. °f a separate
condition mad' be the aubj
enforent action
EC I %V E.D
JAN
DEVELOPMENT SERVICES GU L
CITY OF EDMONDS
�G GUI l
W.14
fa-
01/08/14
DESIGN: MOQ
DRAWN: JCS
CHECK: DMT
JOB NO: 13205.10
DATE: 01 /08/ 14
W
U
W
0
W
N N
O
_! 00
iCL 0)
0
Z
N
'q*
N
N
O
e—
O
SHEET:
Q
N
a
Z
O
W
wlH
Mlfl��011