ENG GEOTECH LETTER FOR STRM MNGMT FACILITYCOBALT
G E 0 S C I E N C E S
Date: Jan 21 & 22, 2020
Contractor: Stromme
Observations:
Project: Shanks SFR
Location: 730 Cary Road
Cobalt Geosciences, LLC
P.O. Box 82243
Kenmore, Washington 98028
Job No.: 2019-199
Weather: Clouds 45
At your request and authorization, Cobalt Geosciences, LLC was on site to evaluate the soil
conditions in the area of the infiltration trenches south and east of the residence.
We observed 1 to 1.5 inch washed rock placed over parallel perforated PVC pipes in the trenches
as generally shown on the civil drawings. The soils at the base of the trenches appeared to consist
of loose to medium dense, silty -fine to medium grained sand.
The trenches are approximately 8o feet in length and 2 feet by 2 feet in size filled with washed
rock. The PVC pipes are generally centered in the trenches with about 12 inches of rock below
and above the pipes.
The soils in the trenches generally appear consistent with the soils encountered in our previous
test pit excavations. Due to the presence of the washed rock, it was not possible to observe the
soil conditions throughout the trench areas.
Sincerely,
Cobalt Geosciences, LLC
T
Phil Haberman, PE, LG, LEG
Principal
PH/sc