Final Geotechnical Letter, BLD20140317, 15911 74th Pl W, Edmonds.pdfI
July 15, 2016
Mr. Leroy Saunders
c/o Mr. Laurey Tobiason
Tobiason & Company, Inc.
20434 10h Place SW
Seattle, WA 98166-4106
Re: Final Geotechnical Inspection Letter
New Single Family Residence
15911 - 74" Place West
Edmonds, WA
Permit #: BLD20140317
Dear Mr. Saunders,
Geotechnical Er sneers, Geologms
& Envi-0-timerital Specialists
This is our final letter summarizing the geotechnical inspections for the project. Geotechnical
inspections were conducted by GEO Group Northwest from October 8, 2015 through March 31,
2016 and 71 field reports were generated. The field reports were provided to the City of
Edmonds, the property owner - Mr, Leroy (Dean) Saunders, and the general contractor - Murphy
Building Company. In accordance with the special inspections requested by the City of
Edmonds, our inspections consisted of following:
I Monitoring of the site excavation: The site appeared stable during site excavation. Site
excavation occurred for the house foundation, the catchment retaining wall at the back of
the lot and for the construction of the Ultra block retaining walls along the north and west
sides of the lot.
2. Soil preparation and compaction: The house foundation and rear catchment, retaining wall
are supported on pipe piles and the subgrade was acceptable. Soils supporting the north
and west block retaining walls were confirmed to be firm and acceptable for supporting
the walls. The driveway subgrade soil was confirmed to be satisfactory. Compaction of
fills was observed for the driveway utility crossings, below the garage slab and below the
front patio slab and confirmed to be satisfactory based on probing.
13240 NE 201h Street, Suite 10 Bellevue, Washington 98005
Phone 425/649-8757 Fax 435/649-8758
July 15, 2016
15911 - 74,h Place West, Edmonds
Geotechnical Final Letter
3. Retaining wall construction: Construction of the Ultra block retaining walls along the
north and west sides of the lot was observed and the wall construction appeared
satisfactory.
4. Pipe pile installation: The installation of the pipe piles was monitored and the specified
pipe pile driving refusal criteria was verified. Based on our observations the piles were
installed in accordance with the plans and specifications.
3. Footing/retaining wall drain installation: We observed the installation of perforated 4-inch
diameter PVC footing drains behind the Ultra block retaining walls, behind the rear
catchment concrete retaining wall and around the perimeter of the house. The footing
drain was bedded in washed rock and the washed rock protected by geotextile filter fabric.
A drainage zone of 5/8 inch crushed rock was installed behind the Ultrablock retaining
walls.
6. Wet Season Monitoring: Temporary erosion and sediment control was monitored during
the wet season (October thru March): Site inspections were performed following storm
events and on a weekly basis durinc,?-I the wet season. Site erosion control measures were
installed and regularly maintained by the general contractor and no offsite erosion control
issues were observed.
Based on our site observations it is our opinion that the geotechnical aspects of the project were
completed in conformance with the geotechnical recommendations for the project.
GEC} Group Northwest, Inc.
July 15, 2016
15911 - 74'h Place West, Edmonds
Geotechnical Final Letter
0
Please contact us if you have any questions.
Sincerely,
GEO GROUP NORTHWEST, INC.
X7
Al I
William Chang, P.E.
Principal
N
cc: Mr. Bob Murphy, Murphy Building Company (rcm@murphybuilding.com)
Patrick Lawler, City of Edmonds (Patrick.lawler@edmondswa.gov)
Kristin Johns, City of Edmonds (Kristin.johns@edmondswa.gov)
JoAnne Zulauf, City of Edmonds (JoAnne.zulauf@edmon-dswa.gov)
GEO Group Northwest, Inc.