HomeMy WebLinkAboutRS_Geotech_Report__v1_20181127Robert M. Pride, LLC Consulting Engineer
May 19, 2014
Mr. Darrell Offe
Offe Engineers
13932 SE 159th Place
Renton, WA 98058
Re:Geotechnical Assessment
Proposed Short Plat
NE 6th Street & Ilwaco Place
Renton, Washington
Dear Mr. Offe,
This report provides subsurface soil information regarding discharge of storm water on
this new short plat development located on the west side of Ilwaco Place and south of
NE 6th Street in Renton. It is understood that this short plat of eight new residences will
include a storage pond at the northeast corner of this site.
This rectangular property measures 295 x 161 feet and is relatively flat. There is an
existing residence and garage on the northwesterly side of this property (568 Hoquiam
Avenue). Field exploration included the excavation of four auger borings as shown on
the attached Drawing No. 1. Summary logs of these test pits are attached to this report.
Based on our site investigation and geologic research the upper loose topsoils are
underlain by dense to very dense glacial till soils. Shallow groundwater is perched on
top of these dense glacial deposits that will prevent onsite infiltration into the subsoils.
Onsite storm water will be directed into the pond at the NE corner of the site for
eventual discharge to the storm system. Foundations for the new residence should
extend down 18 inches onto the medium dense to dense native soils using a soil bearing
value of 2000 psf. Please call if there are any questions.
Robert M. Pride
Principal Geotechnical Engineer
dist:(1) addressee
rmp:JayMarc6thSt1
Robert M. Pride, LLC Page 1
13203 Holmes Point Drive NE Kirkland, WA 98034
SUMMARY LOGS OF TEST PITS
HA-1 Located in proposed pond area at the NE corner of site
0.0 to 0.8ft Topsoil – Silty Sand; dark brown, loose, moist;
0.8 to 2.7ft Silty Sand; brown, medium dense, moist to wet;
2.7 to 3.5ft Silty Sand; grey brown, very dense, wet; glacial till; groundwater at 2.0
feet;
HA-2 Located on Lot 7
0.0 to 0.8ft Topsoil; dark brown, loose, moist;
0.8 to 2.8ft Silty Sand; orange brown, loose, moist;
2.8 to 3.5ft Silty Sand; grey brown, very dense, wet; glacial till; groundwater at 2.6
feet;
HA-3 Located on Lot 1
0.0 to 0.6ft Topsoil; dark brown, loose, moist;
0.6 to 2.5ft Silty Sand with gravel; orange brown, loose, moist;
2.5 to 3.0ft Silty Sand; grey brown, dense, wet; weathered glacial till; groundwater at
2.6 feet;
HA-4 Located on Lot 5
0.0 to 0.3ft Topsoil; dark brown, loose, moist;
0.3 to 2.0ft Silty Sand with gravel; light brown, medium dense, moist to wet;
2.0 to 3.0ft Silty Sand; grey brown, very dense, wet; glacial till; groundwater at 2.0
feet;
Robert M. Pride, LLC Page 2
13203 Holmes Point Drive NE Kirkland, WA 98034