Report (41) CONSULTANTS Y/GEO [CG�/�
NORTHWEST
TECHNICAL MEMORANDUM
DATE: October 10, 2016 '��d PR�,cFs
FROM: Brad L. Hupy, PE, GE - Principal Engineer
Britton W. Gentry, PE, GE -Principal Engineer
To: Don Durst - D R Horton a��� ,�,
RE: Summit Ridge ' W.
Lot 150 & 157 Side Yard Retaining Walls
GCN Project: 1062 Expires 6/30/2017
Lots 150 and 157 are located on the north side of Black Walnut Street on the west and east
ends of the street that is within the development. Native soil on the west side of Lot 150 and
the east side of Lot 157 is retained by short retaining walls.The wall on Lot 150 has not yet
been constructed. The wall on Lot 157 was recently completed.
I visited the site on October 9 to determine the soil conditions that will govern the wall design.
The soil at the base of the wall in Lot 150 is weathered rock. There is 1-112 to 2 feet of soil
above the rock that will need to be retained. The slope above the retaining wall is inclined
upward at (2H:V (horizontal to vertical). Provided exposed wall height is no more than 2 feet (3
units) the retaining wall can be constructed as non-engineered landscaping structure. The wall
is stable with respect to sliding and overturning and will perform as intended.
The recently constructed wall on the east side of Lot 157 varies from about 1/2 foot tall near at
the front of the lot to 4 feet at the elevated back yard. I observed the excavated lot condition
on May 25, 2016 when observing footing subgrade and drainage conditions. I noted in May
that the excavation for footings included removing several feet of rock. I probed behind the
constructed wall On October 9 , 2016 to confirm the earlier observation. Probing confirmed that
the wall does in-fact retain intact rock. The wall is stable with respect to sliding and
overturning and will perform as intended.
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