HomeMy WebLinkAboutDEV 2016-0056; 7603 ROMERIA ST; FINAL SOILS REPORT; 2020-03-03K.F. Stephens, Inc. File No. 1098E2-19 February 4, 2019
The grading was performed for the purpose of scarifying the surface and placing Class II Base
material under the slab of the existing level building pad for the construction of the proposed
residential structure.
SECTION No. 2. SOIL CONDITIONS
Soils used in the fill were those generated from the on-site grading operation and imported from
off site.
Soils encountered during grading were substantially the same as those encountered in the
Preliminary Soils Investigation dated October 22, 1971, prepared by Benton Engineering, Inc.,
Project No. 71-10-18F, and in our Update to Preliminary Soils Investigation and Report of
Compacted Filled Ground dated March 1, 2017, Addendum I dated July 31, 2017 and Addendum
II dated May 1, 2018.
EARTHWORK
Preparation: Prior to placement of fill, the areas to receive fill were scarified, watered and
compacted to 90 percent.
Placing and compacting fill: Fill soil was placed, watered and mechanically densified in the areas
indicated on attached Plate No. 1. A D-5 ripped each lot down 12", the soils were moisturized and
the sub grade recompacted. A representative of our firm tested and recorded the results. Class II
was brought in to each lot and compacted with D-5. Class II base material was verified to be a
minimum of 12 inches in depth for each house pad. A representative of our firm tested and
recorded the results. The sub grade passed all tests as required and the 12" section of Class II
passed all tests as required.
Field density test results: To verify compaction, field density tests were performed in
accordance with applicable American Society of Testing and Materials (ASTM) test methods.
Test method ASTM D1556-82 was used at the indicated locations.
SECTION No. 3. SUMMARY AND RECOMMENDATIONS
Based on the work and tests described hereinbefore and work description set forth in Section 1,
'Scope', we conclude:
1. The filled ground has been compacted to 90%.
2. The placement of fill has been accomplished in accordance with the grading
specifications and with current standard practices.
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K.F. Stephens, Inc. File No. 1098E2-19 February 4, 2019
3. Spread footings will have a minimum allowable bearing value of at least 1500
pounds per square foot. The allowable bearing value will be considerably more
for footings larger than 12 inches wide and/or 12 inches deep. If loads heavier
than 1500 pounds per square foot for continuous footings are anticipated, we
should be contacted for an increased bearing value.
4. The soils are considered to be highly to critically expansive as stated in the
Benton Engineering report dated April 2, 1973. From our field observation and
lab testing, we found the sites to be highly expansive with an expansion index of
104. Due to the possibility of critically expansive soils referenced in the Benton
report, we are amending our recommendations to the following:
5. The following foundation depth is a minimum due to the expansive nature of the
soil and must be used in order to prevent possible damage to the proposed
structures from adverse effects of expansive soils. These recommendations for
footings and slabs are based upon the soil type only and do not take into
consideration the structural requirements.
■ Use continuous exterior perimeter foundations (including door openings).
They should be founded a minimum of 30 inches below lowest adjacent
grade with a minimum width of 12 inches.
■ Interior footing depth should exceed 24 inches below top of slab or 24
inches below lowest adjacent grade for raised floor construction with a
minimum width of 12 inches.
■ Reinforce continuous concrete foundations as a beam with at least one #5
bar positioned 3 inches above the bottom of footing and one #5 bar
positioned 1 inch below top of foundation or top of finish floor.
6. Concrete Slab-On-Grade should be designed by the project's structural engineer
based on anticipated loading conditions. Soil Testers recommends that
conventional reinforced concrete SOG for this project be founded on 6 inches of
Class II Virgin Aggregate Base (With approximately 2% +/-of optimum moisture
content and 90% compaction, relative to the lab maximum dry density, ASTM D
1557), overlying a 12 inch thick zone of adequately placed and compacted
structural fill. We also recommend that a moisture barrier be provided by a
membrane, visqueen 10 mils in minimum thickness or equivalent, be placed at top
of well compacted Class II Aggregate Base, and midway between 4 inches of
moist clean sand.
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K.F. Stephens, Inc. File No. 1098E2-19 February 4, 2019
Floor slabs, as a minimum, should be 5 inches thick with #4 reinforcing steel at
16" on-center each way. Reinforcement should be placed at mid-height of the
slab. The final slab thickness and reinforcement should be determined by the
structural design engineer. Control joints should be provided in accordance with
the recommendations of the structural design engineer.
As an alternative, post-tensioned, PIT, slabs designed by a qualified structural
design engineer may be considered. Geotechnical recommendations for the design
of PIT SOG will be provided upon request.
7. We observed the placement of the subdrains, the fabric around the pipe and the
waterproofing behind the retaining walls.
SECTION No. 4. LIMITATIONS
UNIFORMITY OF SOIL CONDITIONS:
The values presented in this report are based on our evaluation of the observed, exposed soil
conditions. We have assumed that the soil conditions in the remaining portions of the site can be
interpolated without significant deviation in physical properties. We have made a conscientious
effort to select representative test locations and to provide enough tests for a statistically
adequate population in excess of current standard practices. However, parameter values may be
substantially different in other areas due to unforeseeable variations in the soils. Also, the
parameters are affected in time by the moisture-expansion (volume)-pressure changes that
seriously affect the tested values.
ENGINEERING INTERPRETATION:
We are available for consultation and should be made aware of any pertinent condition or
problem. Our conclusions will be re-evaluated and any problem or potential problem solved
with a minimum effort and cost before it gets out-of-hand.
TIME LIMITS:
This report presents conclusions and findings that are valid as of this date. Changes on this site
and adjacent property including grading, improvements, drainage, erosion, etc. may directly
affect the findings, conclusions and recommendations presented herein. Subsequent alterations
or conditions may invalidate these recommendations and values. The values in this report will
probably remain applicable for one year provided the site conditions remain unaltered. After this
period, we should be contacted to inspect the site and review this report so that we may verify its
validity.
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K.F. Stephens, Inc. File No. 1098E2-19 Februa1y 4, 2019
WARRANTY:
Certain risks are involved with geotechnical and soil engineering work, which should be
recognized by those involved. We have performed our services in accordance with current
standard practices and procedures. These practices and procedures are those presently utilized
by members of our profession in this region. We do not express or imply a warranty or
guarantee regarding these services.
OUTSIDE RESPONSIBILITY:
It is the responsibility of the client (firm or person to whom this report is submitted) to ensure
that the information presented herein is made available to the concerned parties. In addition, it is
the client's responsibility to make certain that any construction reflects any applicable
requirements and conforms with the current codes of jurisdictive governmental agencies.
PROJECT CONCEPT:
We should be notified of any changes in the proposed structures, construction, or site grading, or
project concept so that any addendum or modifications to this report may be provided as
necessary.
SOIL TEST METHODS:
Summary of the
GRADING SPECIFICATIONS USED
for
Proposed Residential Building Site
7603 Romeria Street
City of Carlsbad
Maximum Density & Opt Moisture
Density of Soil In-Place
ASTM D1557-78
ASTM D1556-82
Soil Expansion
Shear Strength
Gradation & Grain Size
Capillary Moisture Tension
LIMITING SOIL CONDITIONS:
Minimum Compaction
Expansive Soils
Insufficient Fines
Oversized Particles
UBC STANDARD 29-2
ASTM D3080-72
ASTM Dl 140-71
ASTM D2325-68
90% for "disturbed" soils. (Existing
fill, newly placed fill, plowed ground, etc.)
85% for natural, undisturbed soils.
95% for pavement sub grade within 2' of finish grade and
pavement base course.
Expansion index exceeding 20
Less than 40% passing the #4 sieve.
Rocks over 1 O" in diameter.
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K..F. Stephens, Inc. File No. 1098E2-19 February 4, 2019
Page L-1
LABORATORY TEST RESULTS
The maximum dry densities and optimum moisture contents of the fill materials as determined by the
A.S.T.M., D1557-78, Method A, which uses 25 blows of a 10 pound rammer falling from a height of 18
inches on each of 5 layers in a 4 inch diameter 1/30 cubic foot compaction cylinder, are presented as
follows:
Soil Type
1 Grey, silty, clayey,
fine sand
2 Grey, silty, fine to coarse
sand with gravel (Class II Virgin Base)
Maximum
Dry Density
lb./cu.ft.
121.8
138.6
Optimum
Moisture
Content dry wt.
14.4
6.4
K.F. Stephens, Inc.
Page T-1
TEST SOIL
NO. TYPE
1 1
2 2
3 2
4 2
5 2
6 2
7 *
f.g. = finish grade
DEPTH
OFFILL
ATTEST
IN FEET
f.g.
base
base
base
base
base
base
File No. 1098E2-19
TABLE OF TEST RESULTS
A.S.T.M., Dl556-82
FIELD
MOISTURE
%
19.4
4.3
4.2
6.1
4.7
4.4
6.4
DRY
DENSITY
P.C.F.
110.0
134.4
131.9
130.1
126.7
135.4
138.3
*Maximum density provided by material supplier
MAXIMUM
DRY
February 4, 2019
DENSITY PERCENT
P.C.F. COMPACTION
121.8 90.3
138.6 96.9
138.6 95.2
138.6 93.9
138.6 91.4
138.6 97.7
142.9 96.8