1997-4931 G/CN
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FINAL COMPACTION REPORT
FOR THE GIFTED PRE-SCHOOL (NEW FACILITY)
ENCINITAS, CALlF0RNIA
FOR
THE GIFTED PRE-SCHOOL
2210 ENCINITAS BOULEVARD
ENCINITAS, CALIFORNIA 92024
w.O. 2193-B/D/E-SC
JANUARY 28, 1999
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Geotechnical. Geologic. Environmental
5741 Palmer Way . Carlsbad, California 92008 . (760) 438-3155 . FAX (760) 931-0915
January 28, 1999
W,Q,2193-B/DIE-SC
The Gifted Pre-School
2210 Encinitas Boulevard
Encinitas, California 92024
Attention:
Ms, Susan Ryan
Subject:
Final Compaction Report for the Gifted Pre-School (New Facility), Encinitas,
California
Reference:
"Preliminary Geotechnical Evaluation, The Gifted Pre-School, New Facility, City of Encinitas,
California," W.O. 2193-A-SC, dated April 2, 1997, by GeoSoils, Inc.
Dear Ms, Ryan,
This report presents a summary of the geotechnical testing and observation services
provided by GeoSoils, Inc, (GSI) during the rough earthwork construction and
improvements phase of development at the subject site. Site work within the site and/or
adjacent areas commenced on March 25, 1998 and was generally completed on January
15,1999,
PURPOSE OF EARTHWORK
The purpose of grading was to prepare two relatively level building pads for the
construction of new classroom and office space, including a parking area at the north end
of the property, Cut and fill grading techniques were utilized to attain the desired graded
configurations, Existing topsoils and near surface weathered alluvium were removed to
suitable bearing material then recompacted to grade within the front (south) building pad
as specified in the referenced report, The rear (north) pad was cut to grade, exposing
suitable bedrock materials, The grading plans for this project, prepared by Rinehart
Engineering, Inc" undated, are included with this report as a base map for Plate 1, the
Compaction Test Location Map,
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ENGINEERING GEOLOGY
Earth Materials
Subsurface geologic conditions exposed during the process of rough grading were
observed by a representative of GSI. Materials encountered consisted of claystone,
siltstone (bedrock), silty sand (older alluvium) and clay (existing fill), Earth materials
observed were generally consistent with materials described in GSI (1997).
Structure
A gentle, south dipping contact between older alluvium and underlying bedrock was
observed to daylight in the removal bottom between the north and south building pad,
This transition was treated in accordance with GSI recommendations and is not considered
an adverse condition. Evidence of active faulting or other adverse geologic structures was
not encountered onsite during grading,
GROUNDWATER
Naturally occurring groundwater was not encountered during rough grading of the school
site pad and should not affect the proposed building construction provided that the
recommendations contained in this report and/or provided by GSI are incorporated into
final design and construction and that prudent surface and subsurface drainage practices
are incorporated into the construction plans.
Perched groundwater conditions may not be precluded from developing in the future due
to excess irrigation, altered site drainage or damaged utilities. Should manifestations of
perched conditions (Le., seepage) develop in the future, this office could assess the
conditions and provide mitigative recommendations as necessary, Subdrainage was
provided for the wall supporting the northern parking area,
EARTHWORK CONSTRUCTION
Earthwork operations have been completed in general accordance with the City of
Encinitas grading ordinance and the guidelines provided in the field by this office.
Observations during grading included removals and overexcavation along with general
grading procedures and placement of compacted fills by the contractor.
The Gifted Pre-School
New Facility, Encinitas
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Rough Grading
Preparation of Existing Ground
1.
Deleterious material such as concentrated organic matter and miscellaneous debris
were stripped from the surface and disposed of beyond the limits of grading for the
subject area, prior to placing any fill.
2,
Loose surficial materials (Le., existing topsoils, colluvium, older alluvium and
existing fills) were removed to expose competent bedrock in all areas to receive fill.
3,
In order to provide for more uniform support of the south pad, this area was
overexcavated to a minimum depth of 5 feet below pad grade, then brought to
grade with compacted fill.
4,
Subsequent to completing removals, areas to receive compacted fill were scarified
to a minimum depth of 12 inches, moisture conditioned to at least optimum
moisture content, and then compacted to attain a minimum relative compaction of
90 percent. These areas were then brought to grade with fill compacted to a
minimum 90 percent relative compaction.
6.
All processing of original ground in areas to receive fill, shown on Plate 1, was
observed by a representative of GSI,
Fill Placement
Fill consisted of onsite and import materials which were placed in thin lifts, approximately
four to eight inches in thickness, brought to at least optimum moisture content and
compacted to attain a minimum 90 percent relative compaction. Compaction test results
on fills are presented in the attached Table 1. Import materials primarily consisted of
base rock for pavement areas,
Slopes
Graded Slopes
In general, graded slopes constructed under the purview of this report should perform
satisfactorily with respect to gross and surficial stability, provided that these slopes are
properly maintained,
The Gifted Pre-School
New Facility, Encinitas
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Temporary Slopes
Temporary construction slopes may generally be constructed at a gradient of 1:1
(horizontal to vertical) or flatter in compacted fill, and %:1 (horizontal to vertical) in suitable
bedrock material (provided adverse geologic structures are not present, as determined by
a GSI staff geologist), Utility trenches may be constructed in accordance with guidelines
presented in Title 8 of the California Code of Regulations for Excavation, Trenches and
Earthwork with respect to Type B soil (compacted fill) and stable rock (bedrock),
Construction materials and/or stockpiled soil should not be stored within 5 feet from the
top of any temporary slope, Temporary/permanent provisions should be made to direct
any potential runoff away from the top of temporary slopes.
IMPROVEMENTS CONSTRUCTION
Retaining Wall Construction
Wall foundation excavation was observed by this office and found to be in general
conformance with GSI recommendations, Based on the location of the wall relative to the
limits of compacted fill, a special foundation design, consisting of a deepened shear key
founded in bedrock, was provided by the project structural engineer. Observation and
testing of retaining or building wall backfill was not requested or provided by this office,
Utility Trench Backfill
Native onsite soils and import soils were used as backfill for the fire service trench and
storm drain trench. The required compaction was achieved by mechanical means, The
minimum compaction required was 90 percent of the laboratory standard (ASTM D-1557),
Subgrade and Aggregate Base Testing
The exposed subgrade was tested to a depth of 12 inches. Our tests indicate that the
subgrade materials meet or exceed the minimum requirement of 95 percent relative
compaction of the laboratory standard (ASTM D 1557) for pavements, curb and gutter, and
drive approaches, Our tests indicate that the aggregate base materials meet or exceed the
minimum requirement of 95 percent relative compaction of the laboratory standard (ASTM
D 1557).
The Gifted Pre-School
New Facility, Encinitas
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FIELD TESTING
1,
Field density tests were performed using the sand cone method (ASTM 0-1556-90)
and nuclear method (ASTM 0-2922), Test results are attached as Table 1 at the end
of this report, The approximate locations of field density tests are shown on the
Compaction Test Location Map, Plate 1, which utilize the 1"=20' scale grading plan
prepared by Rinehart Engineering, Inc., as a base map. Storm drain, subgrade and
base testing is presented in Table 1 only,
2,
Field density tests were taken at periodic intervals and random locations to check
the compactive effort provided by the contractor, Based on the operations
observed, test results presented herein are considered representative of the fills
observed under the purview of this report,
3,
Visual classification of the soils in the field as well as random laboratory testing was
the basis for determining which maximum dry density value to use for a given
density test.
4,
Testing was performed on a part time basis.
LABORATORY TESTING
Moisture-Density Relations
The laboratory maximum dry density and optimum moisture content for each major soil
type was determined according to test method ASTM 0-1557-91, The following table
presents the test results:
. . .. ... ... ....
MAX/MI.I.1IDRYDENSIT'lH ..
.....................:tPCFi ........ .
. .. .. .
.. .. .... ... .H. ..H. ... .
...OPTIMUMMq/sTpRE ... .
....... .....CONTENT"......................
16.6
A - Olive brown sandy CLAYEY SILT
B - Brown sandy CLAYEY SILT
114.0
115.5
15.0
C - Brown silty SAND
D - Olive brown CLAYEY SAND
120.0
112,0
12,0
14.0
Baserock
139.0
7.0
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Expansive Soils
Expansive soil conditions have been evaluated for the site. Representative samples of soil
near pad grade were recovered for classification and expansion testing, Expansion Index
(E.I.) testing was performed in general accordance with Standard 18-2 of the Uniform
Building Code,
Representative expansion indices indicate that site soils near pad grade, within the subject
lots, are low expansive (E.I < 50). Test results of 25 and 45 were determined for the south
and north pads, respectively,
RECOMMENDATIONS - FOUNDATIONS/WALLS
Foundation and retaining wall recommendations presented in GSI (1997) are considered
valid and applicable with respect to planned
ADDITIONAL DEVELOPMENT CRITERIA
Graded Slope Maintenance and Planting
Water has been shown to weaken the Jnherent strength of all earth materials. Slope
stability is significantly reduced by overly wet conditions, Positive surface drainage away
from graded slopes should be maintained and only the amount of irrigation necessary to
sustain plant life should be provided for planted slopes. Over watering should be avoided
as it can adversely affect site improvements, Graded slopes constructed within and
utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial
slope stability enhanced by establishing and maintaining a suitable vegetation cover soon
after construction, Compaction to the face of fill slopes would tend to minimize short-term
erosion until vegetation is established. Plants selected for landscaping should be light
weight, deep rooted types that require little water and are capable of surviving the
prevailing climate.
Landscape Maintenance
Only the amount of irrigation necessary to sustain plant life should be provided, Over
watering the landscape areas could adversely affect proposed site improvements, The
slope areas should be planted with drought resistant vegetation. Consideration should be
given to the type of vegetation chosen and their potential effect upon surface
improvements (i.e, some trees will have an effect on concrete flatwork with their extensive
root systems),
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New Facility, Encinitas
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From a geotechnical standpoint, leaching is not recommended for establishing
landscaping. If the surface soils are processed for the purpose of adding amendments
they should be recompacted to 90 percent minimum relative compaction.
. .
Drainage
Positive site drainage should be maintained at all times. Drainage should not flow
uncontrolled down any descending slope, Water should be directed away from
foundations and not allowed to pond and/or seep into the ground, Pad drainage should
be directed toward the street or other approved area, Roof gutters and down spouts
should be considered to control roof drainage, Down spouts should outlet a minimum of
three feet from proposed structures and/or in accordance with the recommendations of the
design civil engineer.
Additional Site Improvements
If in the future, any additional improvements are planned for the site, recommendations
concerning the geological or geotechnical aspects of design and construction of said
improvements could be provided upon request. Proposed pools or other appurtenant
structures should consider that excavation difficulties will likely be encountered in some
areas where dense bedrock may be encountered,
Additional Grading
This office should be notified in advance of any additional fill placement, regrading of the
site, or trench backfilling after rough grading has been completed, This includes any
grading, utility trench and retaining wall backfills. All excavations should be observed by
one of our representatives and conform to CAL-OSHA and local safety codes,
REGULATORY COMPLIANCE
Removals, processing of original ground, cuts and fills have been observed and
compaction testing performed under the purview of this report have been completed using
the selective testing and observations services of GeoSoils, Inc. Earthwork was found to
be in general compliance with the Grading Code of the City of Encinitas, California. Our
findings were made and recommendations prepared in conformance with generally
accepted professional engineering practices and no further warranty is implied nor made.
This report is subject to review by the controlling authorities for this project. GeoSoils, Inc.
is not responsible nor liable for work, testing or recommendations performed or provided
by others,
The Gifted Pre-School
New Facility, Encinitas
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The opportunity to be of service is sincerely appreciated. If you should have any
questions, please do not hesitate to call our office.
Respectfully submitted,
GeoSoils, Inc.
~ //-
~~-
Robert G, Crisman
Engineering Geologist,
RGC/ARK/JPF/mo
Attachments:
Distribution:
(4) Addressee
The Gifted Pre-School
New Facility, Encinitas
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Table 1
FIELD DENSITY TEST RESULTS
TEST DATE TEST RELATIVE . TEST SOIL
NO. COMPACTION METHOD . TYPE
(%)
1 03/27/98 PARKING AREA 91.0 20.4 103.6 90.0 5C A
2 03/27/98 PARKING AREA 94.0 19.7 102.9 90.0 NO A
3 03/27/98 PARKING AREA 97.0 21.7 102.3 90.0 NO A
4 03/27/98 PARKING AREA 98.0 21.3 104.3 90.0 NO B
5 03/27/98 PARKING AREA 99.0 18.8 103.8 90.0 NO B
6 03/27/98 PARKING AREA 100.0 16.9 1 06.4 92.0 NO B
7 03/27/98 PARKING AREA 101.0 16.9 104.1 90.0 5C B
8 03/27/98 PARKING AREA 102.0 17.9 106.0 92.0 NO B
9 03/27/98 PARKING AREA 99.0 17.5 105.5 91.0 NO B
10 03/30/98 PARKING AREA 5G 16.4 107.2 92.0 NO B
11 03/30/98 PARKING AREA SG 16.8 106.5 92.0 NO B
12 03/31/98 SOUTH BUILDING PAD 91.0 13.1 109.6 91.3 NO C
13 03/31/98 RTHWEST BUILDING PAD 92.5 12.6 110.1 91.7 NO C
14 03/31/98 SOUTHEAST BUILDING PAD 93.5 13.6 110.5 92.1 NO C
15 03/31/98 RTHEAST BUILDING PAD 93.5 13.2 108.8 90.7 NO C
16 03/31/98 SOUTH BUILDING PAD 94.5 12.9 108.7 90.6 SC C
17 04/02/98 SOUTH BUILDING PAD FG 17.0 104.3 90.0 NO B
18 04/02/98 SOUTH BUILDING PAD FG 14.4 109.4 94.0 NO B
19 04/08/98 CENTER BUILDING 94.0 18.7 104.3 90.3 NO B
20 04/08/98 CENTER BUILDING 95.0 19.1 104.5 90.4 NO B
21 04/08/98 CENTER 3UILDING 95.5 19.7 104.0 90.0 NO B
22 04/08/98 CENTER BUILDING 96.0 19.3 104.5 90.5 NO B
23 04/08/98 CENTER BUILDING FG 18.7 106.0 91.7 NO B
24 04/15198 SOUTH PARKING SG 17.5 107.6 93.0 NO B
25 04/15/98 PARKING LOT SG 16.0 111.2 96.0 NO B
26 04/16198 SOUTH PARKV1EW SG 16.8 109.6 95.0 NO B
27 04/16/98 AREA SG 13.2 111.3 92.0 NO C
LEGEND:
SG-SUBGRADE
FG- FINISH GRADE
SC- SAND CONE
NO- NUCLEAR DENSOMETER
W.O. 2193-B-SC
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Table 1
FIELD DENSITY TEST RESULTS
TEST
NO.
SO-1 4/23/98
SO-2 4/23{98
SO-3 4/23/98
SO-4 4/23/98
SO-5 5/8/98
FS-1 11/17/98
SOUTH PARKING
LOT
LOT
LOT
TRENCH BACK FILL
SOUTH FIRE SERVICE
LEGEND:
FG- FINISH GRADE
SC- SAND CONE
NO- NUCLEAR OENSOMETER
The Gifted Pre-School
Excel: e:1210012193d
'ELEVATION MOISTURE DRY . RELATIVE.. TEST SOIL
.. CONTENT COMPACTiON
OR DENSITY METHOD TYPE
DEPTH(ft,) (%) (pcf) (%)
-2.0 18.4 107,1 92.0 NO B
-1.0 16.2 104.3 90.0 NO B
-2.0 18.6 107.8 93.0 NO B
-1.0 16.6 107.7 93.0 NO B
FG 17.2 105.1 92.2 SC A
88.0 14.9 101.2 90.3 NO 0
W.O,2193-D-SC
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Table 1
FIELD DENSITY TEST RESULTS
TEST
NO.
DATE
RELATIVE TEST SOIL
COMPACTION METHOD TYPE
(%)
SG 14.9 107.0 95.1 ND D
SG 17.2 109.2 95,8 ND A
SG 18.2 109.0 95.6 ND A
SG 17.9 109.2 95.8 NO A
SG 17.0 109,6 96,1 NO A
SG 16.8 109.2 95.8 ND A
1 11/20/98 DRIVEWAY APPROACH
2 12/19/98 SIDEWALKIENTRANCE
3 1/13/99 N. PARKING
4 1/13/99 N. PARKING
3 1/14/99 S. E. PARKING
4 1/14/99 N.E. PARKING
1 1/15/99 NORTH SIDE ENTERANCE FG 7.5 133.6 96.1 NO BASE
2 1/15/99 NORTH SIDE ENTERANCE FG 7.0 134.5 96.8 ND BASE
3 1/15/99 NORTH SIDE ENTERANCE FG 7.9 136.8 98.4 NO BASE
4 1/15/99 EAST SIDE DRIVEWAYS FG 7.8 136.2 97.9 ND BASE
5 1/15/99 EAST SIDE DRIVEWAYS FG 8.1 135,5 97.5 ND BASE
6 1/15/99 EAST SIDE DRIVEWAYS FG 7.2 134.6 96.8 ND BASE
LEGEND:
FG- FINISH GRADE
SG - SUBGRADE
ND- NUCLEAR DENSOMETER
The Gifted Pre-School
Excel: e:121oo12193e
W.O. 2193-E-SC
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GeoSoils, Inc.
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