HomeMy WebLinkAbout6573-3letter-07142020.pdf15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704 • FAX (425) 449-4711
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
July 14, 2020
ES-6573.03
Richmond American Homes of Washington, Inc.
20829 – 72nd Avenue South, Suite 110
Kent, Washington 98032
Attention: Mr. Zachary Schneider
Subject: Final Report – MSE Fill Rockery
Canyon Terrace – Lots 3 to 7
12303–12333 Southeast 191st Street
Renton, Washington
Reference: Earth Solutions NW, LLC
Rockery Design and Notes
ES-6573.03, dated August 2, 2019
Dear Mr. Schneider:
In accordance with your request, Earth Solutions NW, LLC (ESNW), provided earthwork
observation, compaction testing, and geotechnical consulting services at the subject site. ESNW
previously provided the referenced rockery design for this project. As part of the preparation of
this letter, the daily field reports documenting field observations and field density testing were
reviewed.
Our services during the recent rockery construction at Lot 3 through Lot 7 included providing on-
site observations and testing on a part-time basis from June 16, 2020 to July 7, 2020. During
this time, our representatives made 11 site visits to observe earthwork activities and test structural
fill placed behind the mechanically stabilized earth (MSE) fill rockery supporting the backyards
and existing slope areas of the subject lots.
The MSE fill rockery was constructed to support the transition between finish building pad grades
and neighboring (off-site) properties. ESNW representatives confirmed support and stability
characteristics at the keyway to be suitable for support of the final rockery configuration.
Drainage behind the rockery consisted of at least 18 inches of quarry spalls and a four-inch-
diameter perforated drainpipe placed behind the rockery face boulders. In addition, a six-inch-
diameter tightline pipe servicing individual lots (storm drain system) was installed in conjunction
with the rockery construction.
Richmond American Homes of Washington, Inc. ES-6573.03
July 14, 2020 Page 2
Earth Solutions NW, LLC
ESNW representatives observed the size and quality of the rocks used for construction to be
suitable for the final heights of the rockery. ESNW observed geogrid reinforcement (Miragrid
5XT) placed behind the MSE fill portion of the rockery to be placed in general accordance with
the lengths, strengths, and frequency specified in the approved plans and our geotechnical
recommendations. The rockery batter was observed to be consistent with our geotechnical
recommendations and industry standards. Rock placement was observed to be suitable. Field
density test results of rockery backfill indicate adequate compaction of at least 95 percent was
achieved at tested locations.
Based on our observations and testing, the rockery was constructed in general accordance with
the approved plans and our geotechnical recommendations.
We trust this letter meets your current needs. If you have any questions, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
B. Tyler Scalise Keven D. Hoffmann, P.E.
Assistant Field Supervisor Senior Project Manager
07/14/2020