HomeMy WebLinkAboutCT 82-05; TRACT 7615 SOUTH SIDE OF TAMRACK ROAD; SURFICIAL SLOPE FAILURE; 1985-11-06CT 8J--os-.·
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SURFICIAL SLOPE FAILURE
TRACT 7615, SOUTH SIDE
OF TAMARACK, ROAD
CARLSBAD, CALIFORNIA
CONDUCTED FOR:
MOLA DEVELOPMENT
6994 EL CAMINO REAL
SUITE 208
CARLSB~D, CALIFORNIA 92008
RECEIVED
NOV 6 1985
MOLA DEVELOPMENT
SAN DIEGO
ACTION GEOTECHNICAL CONSULTANTS, INC.
w.O. 3869
October 28, 1985
• ACfION
GEOTECHNICAL CONSULTANTS INC.
October 28, 1985
Mola Development
6994 El Camino Real
Suite 208
Carlsbad, California 92008
Attn: Mr. John Millett
Gentlemen:
W.O. 3869
Subject: Surficial Slope Failure
Tract 7615, South Side·
of Tamarack Road
Carlsbad; CA.
At your request, we have inspected a surficial slope failure
at the subject site. The slope failure was observed on August
16, 1985 and is roughly 25' x 25' x 3'. Other observations
were also made:
1. Generally it appears that overwatering prevails through-
out this development, both on slope fa6es and on'itidividual
lots. Due to the vulnerability of the dominantly sandy
soils in Tract 7615, associated erosion is quick to result.
2. A subdrain observed at the base of slope below the "slump"
appeared to be silted in.
3. Slopes along Tamarack appeared to be over saturated and
water was observed flowing from the scarp of said "slump".
4. The slopes above Tamarack are planted with a dence vine
like vegetation.
CAUSE (S)
Slippage occurs most often along irregular shallow planes, essen-
. tially parallel to the slope surface and/or low near ve~tic~l
faces are exposed where prior tension cracks prevailed. The
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MOLA DEVELOPMENT
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latter are a result of clayey matrix materials
W.O. 3869
drying out to form tension cracks .. ~he lateral e~tent of such
crack alignments are goverened by the make-up of dominant soil
types i~. predominantly granuJar (short lenghts) or cohesive
(longer lengths).
The consistent source of water is from a well spaced irrigation
system of sprinkler heads above ground and possible leaks ~n
pipe joints below ground surface.
WEAK FILL -With the passage of time, thus allowing for the effects
weathering to play their role in modifying the characteristics of
the in-place materials (soil and bedrock), all materials are
sufficiently altered to confuse even the most careful analysis
of its in-place qualities. Furthermore, IIweatheringll is an
easily applied term to cover the general deterioration of in-
place soils and as it is exposed to a host of influences, namely:
daily temperature changes; moisture fluctuations; animal traffic;
artificial influences; chemical processes; vegetation root systems;
etc.
RECOMMENDATIONS
Our recommendations include the following:
1) Reduce watering.
2) Inspect, test and repair, if necessary, the irrigation
system.
3) Clear subdrain outlets to prevent build-up of hydrostatic
forces within slope.
ACTION GEOTECHNICAL CONSULTANTS, INC.
MOLA DEVELOPMENT
Page 3
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w.o. 3869
4) Repair slump by stripping vegeatation fro~ slump and
excavating 12" x 24" deep trenches parallel to slope
at two (2') foot vertical intervals across the entire
width of the slump. Within these trenches drive six
(6') foot long T-Bar fibergalss fence posts on three
(3') foot centers a minimum of four (4') feet below
bottom of trench. To the posts redwood batens may
be lashed and trenches backfilled and compacted.
Finally, landscaping should be performed to re-
store face of slope to original grade.
The above work may be accomplished by hand operations so' as
to minimize disturbance of the existing slope.
It is further recommended that representative of this firm
be present during slope repair operation in order to advise
on hitherto unforseen conditions.
This report is issued with the understanding that it is the
responsibility of the owner, or of his representative, to
ensure that the information and recommendations contained
here are called to the attention of the Architects and En-
gineers for the project and incorporated into tl1e plans
and that the necessary steps are taken to see that the
Cons tractors and Subconstractors carry out such recommen-
dations in the field.
This report is subject to review by the controlling authorities
for this project.
We appreciate this opportunity to be of service to you.
Respectfully submitted:
~a~LTANTS raJ~. .
BRUCE A. PACKARD RCE 13801 ROLAND ACUNA ~
VICE PRESIDENT -ENGINEERING STAFF GEOLOGIST ~
ACTION GEOTECHNICAL CONSULTANTS, INC.
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