ENG SPECIAL INSPECTIONSCOBALT Cobalt Geosciences, LLC
GEOSCIENCES
P.O. Box 82243
Kenmore, Washington 98028
Date: September 30, 2019 Project: 86xx 244th Street SW Job No.: 2019-199
Contractor: LDP Location: Edmonds WA Weather: Sun 55
Observations:
At your request and authorization, Cobalt Geosciences, LLC was on site to observe main access
roadway subgrade conditions prior to permeable pavement base course placement.
We observed firm and unyielding pit run and other imported soil materials (crushed rock with
fines) approximately 12 to 18 inches below finish grade in the access roadway area. We
understand that clean angular rock and permeable pavements will be placed at a later date.
The subgrade is suitable to support new permeable pavements at this time. There is no evidence
of soft or loose soils, pumping soils, or unstable areas.
We collected a sample of the sand and gravel soils that were used as subgrade preparation. From
our discussion with the project civil engineer, we understand that these soils must have a Cation
Exchange Capacity of at least 5 meq in order to meet the criteria for pre-treatment. Analytical
testing of this sample yielded a CEC value of 5.4 meq and an organic content of 1.8 percent.
We will return upon request.
Sincerely,
Cobalt Geosciences, LLC
T
Phil Haberman, PE, LG, LEG
Principal
PH/sc
COBALT Cobalt Geosciences, LLC
GEOSCIENCES
P.O. Box 82243
Kenmore, Washington 98028
Date: June 26, 2019 Project: 86XX 244th Street SW Job No.: 2019-199
Contractor: LDP Location: Edmonds WA Weather: Sun 70
Observations:
At your request and authorization, Cobalt Geosciences, LLC was on site to observe clearing and
grubbing of topsoil and other features on site.
We discuss the construction schedule with the contractor and observed bare soils throughout the
site. All roots were removed and the site has been cleared to native soils.
We will return upon request.
Sincerely,
Cobalt Geosciences, LLC
ar
T
Phil Haberman, PE, LG, LEG
Principal
PH/sc
COBALT Cobalt Geosciences, LLC
P.O. Box 82243
G E 0 S C I E N C E S
Kenmore, Washington 98028
Date: July 10, 2019 Project: 86XX 244th Street SW Job No.: 2019-199
Contractor: LDP Location: Edmonds WA Weather: Sun 70
Observations:
At your request and authorization, Cobalt Geosciences, LLC was on site to general condition of
backfill as well as subgrade preparation for the main access roadway. The roadway subgrade was
cut into the medium dense till and subsequently filled up to subgrade with sand and gravel (pit run)
and local crushed rock.
We have previously reviewed the provided geotechnical report by Liu and Associates and the native
soils in the roadway area are consistent with those described in his report. The imported fills above
the native soils are permeable and suitable to support new roadways as well as provide some
infiltration capabilities.
We will return upon request.
Sincerely,
Cobalt Geosciences, LLC
T
Phil Haberman, PE, LG, LEG
Principal
PH/sc