HomeMy WebLinkAbout1600_Grant_September_23.pdfCobalt Geosciences, LLC
P.O. Box 82243
Kenmore, Washington 98028
Date: September 23, 2021 Project Townhomes Job No.:
Contractor:Location: 1600 Grant Weather: Sunny 58
At your request and authorization, Cobalt Geosciences, LLC was on site to evaluate the backfill
behind a new hydrant at 1600 Grant Avenue South.
We arrived and observed a backfilled area behind a concrete thrust block in water line areas near
the east end of the site. We observed approximately 3 feet of compacted 5/8 minus gravel behind
the block.
No. Depth Location Dry Density %Moisture %Compaction Proctor Value
1 0.5’ 3’ from block 123.5 6.9 97.4 126.8 at 8.2
The density testing yielded results above 95 percent compaction of the modified proctor value
(ASTM D 1557 Test Method). Conditions can change over time. We should review final
conditions of all backfill using a proofroll prior to pavement placement.
Sincerely,
Cobalt Geosciences, LLC
Phil Haberman, PE, LG, LEG
Principal