HomeMy WebLinkAboutCT 05-14; LA COSTA OAKS NEIGHBORHOOD 3.1; FINAL REPORT OF TESTING AND OBSERVATION SERVICES PERFORMED DURING SITE GRADING; 2008-05-16a. I
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FINAL REPORT OF .
TESTING AND OBSERVATION
'SERVICES PERFORMED
DURING SITE GRADING •-
VILLAGES OF LA COSTA ;
THE OAKS NORTH.-
LOT 81 -1 RECREATION AREA
CARLSBAD, CALIFORNIA
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PREPARED FOR
4 REAL ESTATE -
COLLATERAL MANAGEMENT COMPANY
% MORROW DEVELOPMENT INCORPORATED
CARLSBAD, CALIFORNIA .
MAY 169 2008
PROJECT NO 06105-52-20
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.GEOCON '
INCORPORATED
GEOTECHNICAL CONSULTANTS
Proj ect No.506105-52-20
/ May 16,2008
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. Real Estate Collateral Management Company .
% Morrow Development Incorporated
. 1903 Wright Place, Suite 180
Carlsbad, California 92008
,, Attention: Mr. Tim O'Grady •'
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Subject:. VILLAGES OF LA COSTA - THE OAKS NORTH
LOT 81— RECREATION AREA
. .. CARLSBAD, CALIFORNIA
FINAL REPORT OF TESTING AND OBSERVATION
SERVICES PERFORMED DURING SITE GRADING
' Dear Mr. O'Grady: . .,
. In accordance with' your request and our proposal dated February 9, 2006, we have provided.
compaction testing and observation services during the grading of the subject site. We performed our
services during the period of August 16, 2006 through December 18, 2006. The scope of our, services
included: . .
S - • Observing the grading operations, including the removal and/or processing of to soil;
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' colluvium, alluvium, and undercutting the recreation pad where granitic rock was exposed at
grade.
Performing in-place dry density and/or moisture tests in fill placed and compacted at the site.
Performing laboratory tests, to aid in evaluating maximum dry density and optimum moisture S . content and ,shear strength of the compacted fill. Additionally, we performed laboratory tests
on samples 'of soil present at finish-grade to evaluate expansion characteristics and water-
soluble sulfate content.
Preparing an "As Graded" 'Geologic Map.
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Preparing this.final report of grading.
'-The purpose of this report is to document that the grading for Lot 81 - Recreation Area, which consists
of two sheet-graded pads, for ultimate use as a recreation area, has been performed in substantial
conformance with the recommendations of the project geotechnical report and that fill materials have
been properly placed and compacted. We understand the future use of the lower sheet-graded pad will
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6960 Flanders Drive • San Diego, California 92121-2974 • Telephone (858) 558-6900 • Fax (858) 558-6159 - -
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be for the construction of a pool, pool equipthent room, and restroom. The upper, sheet-graded pad will
be a landscaped area and structures are not planned. The grading operations for Lot 81 - Recreation /
Area were performed concurrently with other neighborhoods within The Oaks North project.
GENERAL..
The grading contractor for the project was Pinnick Construction Incorporated of Lakeside, California.
Grading plans for the project were prepared by Hunsaker and Associates and are entitled Rough
Grading and Erosion Control Plans for La Costa Oaks North Neighborhood 3.1, Drawing No. 4464A,
City of Carlsbad approval date July 12, 20077, and Precise Grading and Erosion Control Plans
for: Villages of La Costa, The. Oaks North Recreation Center,. Drawing 4464B, City of Carlsbad
approval dated March 16 2008 We used an electronic version of the grading plans as the base map for
our "As Graded" Geologic Map (Figure 1, map pocket). The: project geotechnical report is entitled.
Update Geotechnical Investigation, Villages of La Costa—The Oaks, Carlsbad, California, prepared by
Geocon Incorporated, dated August 3, 2001 (Project No. 06105-12-04).
References to elevations and locations herein were based on surveyor's or grade-checker's stakes in the
field and/or interpolation from the referenced Grading Plans. Geocon Incorporated does not provide
surveying services and, therefore, has no opinion regarding the accuracy of the as-graded elevations or
surface geometry with respect to the approved grading plans or proper surface drainage.
GRADING
Lot 81 - Recreation Area is located within the northeastern portion of Villages of La Costa - The Oaks
North development. This lOt is located north of the western terminus of San Elijo Road, and west of N
Rancho Santa Fe Road. Prior to grading, the site primarily consisted of ridge topography with tributary
drainages of shallow surficial deposits draining northeasterly. Grading for the site consisted of daylight
cuts and fills to achieve finish-grade elevations. ,
Grading began with the removal and export of brush and vegetation from the area to be graded.
Topsoil, alluvium; and"colluvium were removed to expose formational. materials. Within these areas
and prior to placing fill, the exposed (overexcavated) ground surface was scarified (where possible),
moisture conditioned as necessary, and compacted. Areas of remedial grading that exposed granitic
rock were not scarified. Fill materials derived from on-site blasting, excavations, and crushed materials
were then placed and compacted in layers until the design elev4tions were attained. In addition, fill was
placed as a result of undercutting where granitic rock was exposed at grade. The undercut' on Lot 81
consisted of undercutting to a depth of approximately 1 foot below the deepest utility.
Project No:. 06105-52-20 -2- - . ' May 16,2008
Fill Materials and Placement Procedures
The on-site fill materials generally varied between angular gravels and boulders produced by blasting
of hard metavolcanic to clayey fine sands, and sandy to clayey gravels. Structural fill placed and
ompacted at the site consisted of material that can be classified into three zones:
Zone A - Material placed within 3 feet from pad grade, 6 feet from parkway grade, and within
roadways to at least 1 foot below the deepest utility consists of "soil" fill with a maximum,
particle dimension of 6-inches.
.' Zone B - Material placed within 10 feet from pad grade and below Zone A consists of "soil-
rock' fill with a maximum' particle dimension of 12 inches and on the outer 6 feet of fill slopes
and .2 feet below Zone A for fills in roadways and parkways.
Zone C - Material placed below Zone B consisted of 'soil-rock" fill with a maximum particle
dimension of 48 inches.
Placement. procedures for "soil-rock" fill consisted of spreading and compacting the, material with a D9'
or larger Caterpillar bulldozer with a maximum lift size of approximately 3 feet. Materials, placed as
"soil-rock" fill were watered heavily during spreading to help. properly fill voids with finer material
and "seat" the larger rocks. During the placement of each lift, the contractor applied compactive' effort
to the fill by wheel-rolling 'and compacting with'loaded rock trucks. '
"Soil fill" was placed in lifts no thicker than would allow for adequate bonding and compaction. The
soil' was moisture conditioned as necessary and mixed during placement and then compacted utilizing
conventional heavy-duty compaction equipment.
We observed compaction procedures during grading operations, and performed in-place density tests to
evaluate the dry density and moisture content of the' "soil" and"sdil-rock" fill material. We performed
in-place density tests in general conformance with ASTM Test Method D 2922 (nuclear). The results
of the in-place dry density and moisture content tests are summarized on Table I. In general, the in-
place density test results indicate that the fill soil has a dry density of at least 90 percent of the
laboratory, maximum dry density near to slightly above optimum moisture content at the locations
tested. The approximate locations of the in-place density tests are shown on the As-Graded Geologic
Map (Figure 1).
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We performed compaction procedures' during the grading for the Recreation Area - Lot 81
concurrently with Neighborhoods 3 1 3 2 3.3 through 3 5 and 3.7 of the Villages of La Costa - The
,Oaks North development. The results presented on Table I apply to Lot 81 - Recreation Area only. As
such, the test numbers are not in consecutive order. Any tests taken outside of the subject neighborhood
will be included in reports for other neighborhoods within The Oaks North
Project No, 06105-52-20 ' ' -' - 3 - ' ' May 16, 2008
We corrected the laboratory maximum dry density and optimum moisture content on fill soils being.
tested containing rocks larger than 3/4 inch using methods suggested by AASHTO T224-86 and others.
The values of maximum dry density and optimum moisture content presented on Table I reflect these
corrections..
We tested samples of material used for fill to evaluate moisture-density relationships, optimum
moisture content and maximum dry density (ASTM D 1557) We performed direct shear tests (ASTM
D 3080), on samples used within fill slopes. We tested samples within the upper 3 feet of finish grade
to evaluate the expansion index (ASTM D 4829) and water-soluble sulfate content (California Test
No: 417). The results of the laboratory tests are summarized on Tables II through V.
SOIL AND GEOLOGIC CONDITIONS
The soil and geologic conditions encountered during grading were found to be similar to those
described in the project geotechnical report Escondido Creek Granodiorite (Kg[e]) was exposed at
grade within cleanouts in pad undercuts and cut areas Compacted fill was placed in areas designated as
Qcf on Figure 1 In addition compacted fill placed in undercut areas is designated as Quc
The "As.Graded" Geologic Map (Figure 1) depicts the general geologic conditions observed. No soil
or geologic conditions were observed during grading that would preclude the continued development
of theproperty as planned.
/ CONCLUSIONS AND RECOMMENDATIONS
1.0 General
1.1 Based on observations and test results, our opinion .i the. soil' engineering. nd the geologic
engineering aspects of the grading to which this report pertains has been performed in /
substantial conformance with the recommendations of the previously referenced project
geote,chnical investigation. Soil and geologic conditions encountered during grading that
differ from those expected by the project soil reports are not uncommon Where such
conditions required a significant modification to the recommendations of the project soil
reports they have been described herein No soil or geologic conditions were observed
during grading that would preclude the continued development of the property as planned
2.0 Finish Grade Soil Conditions .
2.1 Observations and labratory test results indicate that the prevailing soil conditions within the
upper approximately 3 feet of finish grade is considered to be .'non-expansive" (expansion
index [El] of less than 20) as defined by 2007 California Building Code (CBC)
Section 18023.2. Table 2 presents soil :classifications based on the expansion index. A
Project No 06105-52-20 4 May 16 2008
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majority of the soil encountered is planned to posses a "very low' expansion potential
Table IV presents a summary of the indicated expansion index of the prevailing subgrade
soil conditions. -
TABLE2
SOIL CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (El) Soil Classification
0-20 Very Low,
21-50 Low
51-90 Medium
91-130 High
Greater Than 130 Very High
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2.2 We performed laboratory tests on samples of the site materials to evaluate the percentage of
water-soluble sulfate content. Results from the laboratory water-soluble sulfate content tests
are presented in Table V and indicate that the on-site materials at the locations tested possess
"negligible" sulfate exposure to concrete structures as defined by 2007 CBC Section 1904.3
and ACT 318. The presence of water-soluble sulfates is not a visually discernible
characteristic; therefore other soil samples from the site could yield different concentrations.
Additionally, over time landscaping activities (ie., addition of fertilizers and other soil
nutrients) may affect the concentration.
2.3 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, if
improvements that could be susceptible to corrosion are planned, further evaluation by a
corrosion engineer should be performed.
2.4 Although rocks larger than 6 inches were not intentionally placed within the parking' areas,
undercut fill, and the upper 3 feet of pad grade, some 'larger rocks may exist at random
locations. In addition, excavations deeper than the undercut depths may require special
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30 Future Grading
3.1 Additional grading performed at the site should be performed in conjunction with our
observation and compaction testing services. Grading plans for any future grading should be
reviewed by Geocon Incorporated prior to finalizing. Trench and wall backfill materials
should be compacted to a dry density of at least 90 percent of the laboratory maximum dry
density near or above optimum moisture content. This office should be notified at least 48
hours prior to commencing additional grading or backfill operations.
Project No. 06105-52-20'. - 5 - May 16, 2008
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10 Slopes ,.
ti The project slopes consists of cut and fill slopes constructed at .inclinations-of 2:1
(horizontal: vertical) or flatter with maximum heights of approximately 20 feet. Slopes
should be planted, drained, and maintainedto reduce erosion. Slope irrigation should be kept
to a minimum to just support the vegetative cover. Surface drainage should not be allowed to
flow over the top of the slope. . .
5.0 Subdrins r -
5.1 "A canyon subdrain was installed at the general loctioh'shown on the "As-Graded" Geologic
Map (Figure 1). In addition: the subdrain was "as-built" for location and elevation by
the project civil engineer. The subdrains consist of a 6-inch diameter PVC, Schedule 40,
perforated pipe placed incrushed aggregate surrounded by Mirafi 140N (or equivalent) filter.
fabric. The drains were typically placed at least 15 feet below finish grade and constructed at,
a flow gradient of at least 1 percent .
5.2 During construction, the canyon subdrain was tied into the permanent' storm drain system
during improvement phases of development by the'master developer.
6.0 Seismic Design Criteria
6.1 We used the computer program Seismic Hazard Curves and Unform Hazard Response
Spectra, provided by the USGS to calculate the seismic design criteria. Table 6. summarizes
site-specific design, criteria obtained from the 2007 CBC, Chapter 16 Structural Design;
Section 1613 Earthquake Loads The short spectral response has a period of 0.2 second
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TABLE 6
2007 CBC SEISMIC DESIGN PARAMETERS
Parameter .
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Value IBC-06 Reference
Site Class , ' C Tabl 1613.5.2
Spectral Response Class B (short), Ss 1.083g Figure 1613.5(3)
Spectral Response - Class B (1 sec), Si ' 0.408g Figure 1613.5(4)
Site Coefficient, Fa , 1.000 Table 1613.5.3(1)
Site Coefficient, F ' 1.392 Table 1613.5.3(2)
Maximum Considered Earthquake
Spectral Response Acceleration (short), 5MS
1.083g' Section 1613.5.3 (Eqn 16-37)
Maximum Considered Earthquake
. 0.568g Section 1613.5.3 (Eqn 16-38) Spectral Response Acceleration— (1 sec), SM1
5% Damped Design
Spectral Response Acceleration (short), SOS:
. 0.722g Section 1613.5.4 (Eqn 16-39)
5% Damped Design
Spectral Response Acceleration (1 sec), ' 0.379g SectiOn 1613.5.4 (Eqn 16-40)'
Project No. 06105-52-20 - 6 -
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6.2 Conformance to the criteria for seismic design in Table 6 does not constitute any kind of
guarantee or assurance that significant structural damage or ground failure will not occur if a
maximum level earthquake occurs. The primary goal of seismic design is to protect life and.
• not to avoid damage, since such dèsin may be economically prohibitive.
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• 7.0 Foundations .1 '
S 7.1 c The proposed structures 'can be supported on conventional foundations consisting of
S continuous strip footings and isolated spread footings. Continuous footings for the building
should be at least 12 inches wide and should extend at least 18 inches below lowest adjacent
S pad grade. Isolated spread footings shoulcibe at least 24 inches wide and should extend at
5 least 18 inches below lowest adjacent pad grade. Steel,, reinforcement for continuous footings
should consist of at least four No. 4 steel reinforcing bars placed horizontally in the footings,
• two near the top and two near the bottom. The steel reinforcement for spread footings should
5 be designed by the project structural engineer. Figure 2 presents a typical wall/column .
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footing dimension detail. . ', •.
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7.2 i The minimum reinforcement recommended herein s based on soil characteristics only (El of
90 or'Iess) and is not intended to replace reinforcement required for structural considerations. . n
73 The recommended allowable bearing capacity for foundations designed as recommended
herein is 2,000 pounds per square foot (psf). The values presented herein arefor dead plus
'S Jive loads and may be increased by one-third when considering transient loads due towind or
.'.. seismic forces.
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S , 7.4 Foundation excavations should be observedby the geotechnical engineer, (a representative of
Geocon Incorporated) prior to the placement of r'einforcing steel to check that the exposed
• ',soil conditions are similar to those expected and that they have been extended to the
• appropriate bearing.' strata. If unexpected soil conditions are encountered, foundation
• modifications may be required. ..
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' : 75 ' Special subgrade presaturation is not deemed necessary prior to placing concrete; however,/
the exposed foundation and slab subgrade :soil should be moisturized to maintain a moist'
' ' I condition as would be expected in any such concrete placement. . 7.6 Where improvements are planned near the top of a slope steeper than 3:1 (horizontal:
vertical),, special design consideration are recommended due to the tendency for lateral soil
'to movement occur. Improvements that are relatively rigid or brittle such as concrete,
flatwork or masonry walls may experience some distress if'located near the top of a slope, it
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Project No. 0610552-20 ' ., ' , .' _7- ' , ' May46, 2008 5
is generally not economical to mitigate this potential. It may be possible, however, to
incorporate design measures which would permit some lateral soil movement without
causing extensive distress Geocon Incorporated should be consulted for specific
recommendations:
8.0 Concrete Slabs-On-Grade
8.1 Concrete slabs-on-grade should be at least 5 -inches thick as stated in the referenced report.
Minimum slab reinforcement should consist of No..3 steel reinforcing bars placed 18 inches
on center in both horizontal directions and positioned within the upper, one-third of the slab.
The concrete slabs-on-grade should be underlain by at least 4 inches of clean sand and,
where moisture sensitive floor coverings are planned, 'a visqueen moisture inhibitor placed at
the midpoint of the sand should be, provided.
8.2 Crack-control joints should be spaced at intervals not greater than 12 feet and shOuld be
constructed using sawcuts or other methods as soon as practically possible following
concrete placement. Crack-control. joints should extend a minimum depth of one-fourth the
slab thickness. Construction joints should be designed by the project structural engineer.
8.3
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Exterior slabs not subject to vehicle loads .should be at least 4 inches thick and reinforced
with 6x6-W2.91W2.9 (6x6-616) welded wire mesh. The mesh should be placed within the
upper one-third of the slab. Proper mesh positioning is critical to future performance of the:
slab. It has been our experience that the mesh must be physically pulled up into theslab after,,
concrete placement. The contractor should take extra measures to provide proper mesh
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' placement. Prior 10 , construction of slabs, the subgrade should be compacted to at least
- 90 percent of the laboratory maximum dry density near to slightly above optimUm moisture.
8.4' Soil can lift flatwork due to the lightly loaded areas of exterior walkways and patio areas.
Additionally, structures can settle due to wall and column loads These vertical differences
caused by lifting or settlement will likely vary over the area covered by the flatwork, causing
differential slab movements that could result in either a safety hazard or outwardly-opening -
doors hanging up on elevated walkways that abut the structure. Therefore, exterior walkways
- and patio areas where doors open outward abutting the structure with little tolerance of -
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vertical movement should be doweled into the structure at entrances and at joints to prevent
differential movement of such flatwork.
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8.5 • The recommendations of this report are intended to reduce the potential for cracking of slabs -
due to differential settlement of.deep fills or fills of varying thickness. However, even with
the incorporation of the recommendations presented herein, foundations, stucco walls, and'
Project No. 06105-52-20 - 8 - '
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• May 16, 2008
slabs-on-grade placed on such soil conditions may exhibit some cracking due to soil
0 movement and/or shrinkage. The occurrence of concrete shrinkage cracks is independent of
the supporting soil characteristics. Their occurrence maybe reduced and/or controlled by
limiting the slump of the concrete, proper concrete placement and curing, and by the -
placement of crack-control joints at periodic intervals, in particular, where re-entrant slab
corners occur. -
M. If detention basins, bioswales, retention basins, or water infiltration devices are , being
considered, Geocon Incorporated should be retained to provide recommendations pertaining
to the geotechnical aspects of possible impacts and' design. Distress may be caused to'
planned improvements and., properties 'located hydrologically downstream. The distress
depends on the amount of water to be detained, its iresidence time, soil permeability, and
other factors. We have not pei'formed a hydrogeology study at the site. Downstream
properties may be subjected, to seeps, springs, slope instability, raised groundwater,
movement of foundations and slabs, or other impacts as a result of water infiltration.
9.0
9.1
9.2
9.3
Pool/Spa Recommendations
The proposed swimming' pool/spa should be reinforced and designed by. a structural
enginer. The soils have an expansion index category of medium. The corresponding lateral'
pressures used for the design should be equivalent to fluid pressure of at least 40 pcf. The
swimming pool/spa also should be designed for any possible surcharge loading 'if such
nearby loading is a lateral distance from the top of the pool equal to the depth of the pool.
The bottom of the swimming poolispa should not be supported by different types of earth
materials. A layer of common bearing material is needed to provide support for the pool/spa.
If a formational cut/fill 'condition is present on the bottom of the pool/spa,, the bottom of the
excavation should be overexcavated at least 3 feet and recompacted up to rough grade. The
bottom of the excavation should be scarified, moisture conditioned, and compacted prior to
the placementof fill soils. Geocon Incorprated should observe the bottom of the excavation
to verify the geologic conditions.
Surface drainage around the pool/spa should be designed to prevent water from ponding and
seeping into the ground. Surface water should be collected and conducted through non-
erosive devices to the street, storm drain, or other approved water course or disposal' area..,
Leakage from the proposed pool/spa' will create an artificial groundwater condition that will,
likely create instability problems. 'Therefore, all plumbing and the pool/spa should be
absolutely leak free. , 0
Project-No. 06105-5,2-.20
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• 9.4 The deck for the swimming pool/spa should be cast separately of the swimming poollspa,
and water stops should be provided between the bond beam and the deck. Jointing for
• concrete flatwork should. be provided in accordance with the recommendations 'of the
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American Concrete Institute. All joints should be sealed with an approved flexible sealant to
5 reduce the potential for introduction of surface water into the underlying soils.
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5 9.1 Retaining Walls' and Lateral-loads .
• 9. 1..l Retaining walls not restrained at the top and having a level backfill surface should be
5 designed for an active soil pressure equivalent to the pressure exerted by a fluid density
S of 35 pounds per cubic foot (pci). Where the backfill will be inclined at no steeper than 2:1
5 (horizontal: vertical), an active soil pressure of 50 pcf should be used. These soil pressures
• assume that the backfill 'materials within an area bounded by the wall and a 1:1 plane,.
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' extending upward from the base of the wall possess an expansion index of 50. or less. For
those lots with finish-grade soils having an expansion index' greater than 50 and/or where
backfill materials do not conform to the above criteria, Geocon Incorporated should be
consulted for additional recommendations.
9.1.2 Unrestrained walls are those that are allowed to rotate more than 0.001H (where H equals the S. height of the retaining portion of the wall) at the top of the wall. Where walls are restrained
from movement at the top, an additional uniform pressure' of 7H psf should be added to the
above active soil pressure. For retaining walls subject to vehicular loads within a horizontal
S distance equal to two-thirds the wall height, a surcharge equivalent to 2 feet of fill soil
5 . . should be added.
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, 9.1.3' Retaining walls should be provided with a drainage system adequate to, prevent the buildup'
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' of hydrostatic forces ,and waterproofed as required by the project architect. The use of
drainage openings through the base of the wall (weepr holes) is not recommended where the
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- seepage could be'a, nuisance Or, otherwise adverselyaffect the property adjacent to the base
of the wall. The above recommendations assume a properly compacted free-draining backfill
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material (El of 50 br less)with no hydrostatic forces or imposed surcharge load. 'Figure 3
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' presents a typical retaining wall drainage detail. If conditions different than those described
' are expected, or. if specific drainage details are desired,. Geocon Incorporated should be
'contacted for additional recommendations. . .
5 9.1.4 In general, wall foundations founded in properly compacted fill or formational materials
I , ' should possess a minimum depth and width of one foot and may be designed for an
. I , ' allowable soil' bearing pressure of 2,000 psf, provided the soil within 3 feet below the base of
the wall has an expansion index of 90 or less. The proximity of the foundation to the top of a
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S Project No. 06105-52-20 '- 10- ' May 16, 2008
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• slope steeper than 3:1 could impact the allowable soil bearing pressure. Therefore, Geocon
S Incorporated should be consulted where such a condition is expected.
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• density of 300 pcf is recommended for footings, shear keys, or thrust blocks poured neat •,
against properly cOmpactedfill. The allowable' passive pressure assumes a horizontal surface
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• extending at least 5 feet or three times the surface generating the passive pressure, whichever
is greater. The upper. 12 inches of material not protected by floor slabs or pavement should
not be included in the design for lateral resistance. A friction coefficient of'0.35 may be used
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. for resistance to sliding between soil and concrete. This friction coefficient may be combined
with the allowable passive earth pressure when determining resistance to lateral loads.
• 10.0 Slope Maintenance
1 - 10.1 . Slopes that are steeper than 3:1 (horizontal: vertical) may, under conditions that 'are both
difficult to prevent and predict, be susceptible to near-surface (surficial) slope instability.
The instability is typically limited to the outer three feet of the slope and usually does. not
• directly impact the improvements on the pad areas above or below the slope. The occurrence
• of surficial instability is more prevalent on fill slopes and is generally preceded by a period
of heavy rainfall, excessive irrigation, or the migration of subsurface seepage. The
disturbance and/or loosening of the surficial soils, as might result from root growth, soil
' 'expansion, or excavation for irrigation lines and slope planting, may also be a significant
S . contributing factor to surficial instability. Therefore, to the maximum extent practical;
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Disturbed/loosened surficial soil should be either removed or properly recompacted,
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Irrigation systems should be periodically inspected and maintained to eliminate leaks
I and excessive irrigation, and '
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Surface drains on and adjacent to slopes should be periodically maintained to
preclude ponding or erosion. Although the incorporation of the recommendations
5 .. should reduce the potential for surficial slope instability, it will not eliminate the
' possibility and, therefore, it may be' necessary to rebuild or repair a portion -of the
project's slopes in the future.
• 11.0 Site Drainage and Moisture Protection • , •
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• 11.1 Adequate drainage is critical to reduce the potential for differential soil movement, erosion,
- and subsurface seepage. Under no circumstances should water be allowed to pond adjacent
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• to footings. The site should be gra4d and maintained such that surface drainage is directed,
- away from structures and the top of slopes into swales or other controlled drainage devices.
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• Project No. 06105-52-20 - - 11 - - • May 16, 2008
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S Roof and pavement drainage should be directed into conduits that carry runoff away from the
S proposed structure. ' 0
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. 11.2 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks for early detection of water infiltration and detected leaks should be
5 repaired promptly. Detrimental soil movement could occur if water. is allowed to infiltrate
the soil for ,a prolonged period of time.
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5 11.3 If detention basins, bioswales, retention 'basins, or Water infiltration devices aide being
considered, Geocon Incorporated should be retained to provide recommendations pertaining
0 to the geotechnical'aspects of possible impacts and design. Distress may be caused to
0 planned improvements and properties located hydrologically downstream. The distress':
. depends on the amount of water to be-detained, its residence time, soil permeability, and
other factors. We have, not performed a Ffydrogèology study at the site. Downstream
properties may be subjected to seeps, springs, slope instability, raised groundwater,
0 5 0 'movement of foundations and slabs, or other impacts as -a result of water infiltration. Water , 0
5 0 infiltration devices installed within the area of the CMU walls should be constructed do
S ' ' prevent water from intruding into the compacted fill.
5 0 11.4 Landscaping planters adjacent to' paved areas are not recommended due to the potential for 0
5 surface or irrigation water to infiltrate the pavement's subgrade and base course. We
5 0 recommend that subdrains to collect excess irrigation water and transmit it to drainage .
5 .. structures, or impervious above-grade planter boxes be. used. In addition, where landscaping'.
is planned adjacent to the pavement, we r)ecommend construction of a cutoff wall along the
edge of the pavement that extends at least 6 inches below the bottom of the base material.
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LIMITATIONS
The conclusions and recommendations contained herein apply only to our work, with respect to
' grading, and represent conditions, on the date of our final observation on December 18, 2006. Any
subsequent grading, should be done in conjunction 'with our observation and testing services. As used
/ herein, the term "observation" implies' only' that we observed the 'progress of the work with which we
agreed to be involved. Our services did not' include the evaluation or identification of the potential
presence of hazardous or corrosive materials. Our conclusions and opinions as to whether the work
essentially complies with the job specifications are: based on our observations, experience and test
results. Subsurface conditions, and 'the accuracy of tests used to measure such conditions, can vary
S ' greatly at any time. We make no warranty, express'or implied, except that our services were performed
S in accordance with engineering principles generally accepted at this time and location. -
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S Project No. 06105-52-20 . 0 — 12 — . May 16_2008
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S We, will accept no responsibility for any 'subsequent changes., hanges made to the site by others, by the,
S uncontrolled actiOn of water, or by the. failure of Others to properly repair damages caused by the
uncontrolled action of water. The findings and recommen4tions of this report may be 'invalidated'
5 wholly or partially by changes outside our control. Therefore, this report is subject to review and
should not be relied upon after a period of three years.
.',
Should you have any questions regarding this report, or if we may be of further service, please contact
the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Michael C. Ertwine ' , Shawn Weedon 51 , Senior Staff Geologit , '
-' GE 2714
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MCE:SW:dmc
Of ESS/ fEss
Addressee 19
o (e-mail) Real Estate Collateral Management Company
% Morrow Development Incorporated. No. 2714
Attention: Mr. Kevin Sullivan 0 Exp. 06/30/09
OFC
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S Project No. 06105-52-20 5
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428 .. --- VILLAGES OFLACOSTA-THE OAKS NORTH LOT78__/
- LIII [I LOT 81 -RECREATION AREA
EXIST Off 69 43o - - CARLSBAD, CALIFORNIA
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454 //-/ / / / V • . ''j _/ / / / -. ouip \ . N . Quc FILL • . . '1 / / / .7 / / •.- 7 6 I / / / . - 'PADS. p N N A AREA I 1 / / / / .- .- ' / 456 •.' 7 . / -- -. '! \ N N 0.1 '\ N p, \ i 'I . / / ,/ / ./ / / - .• -c\ / -
\ \ \ N • N e ........ ESCONDIDO CREEK GRANODIORITE
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:'-- // / /// ,/ 6 7 -- 7 - • N' \\N —N - N \-NN \'-- .. ........ APPROX. LOCATION OF GEOLOGIC CONTACT
,450 / / / / 61 77 - \ 9 \ \UN (Dotted Where Buried)
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\ \ 5, \ \\ \ \ APPROX. LOCATION OF IN PLACE DENSITY TEST / ._p,I__ ,• - -- -'5' 7 - .' / - — -- - \ .. . \ \ 'i., '\ ' I FG Finish Grade ST SlopeTest
/ - - •/S1
/ _ - _. , OIT N ') \ ' \ \ , APPROX. LOCATION OF SUBDRAIN
- - -
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-
- \\ - N - A 46 ........ APPROX. ELEVATION OF SUBDRAIN (feet) 0/ - N ' N
x,srs -ORAIN .. \ ' ,00 [J APPROX. ELEVATION AT BASE OF FILL (feet) PER 429 7 84,50
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744905 -', — - - - ' INCORPORATED (GO
LOT 212
66 • 7- - -' / N -... . -- \\ 'N ... 5- . I GEOTEO-INICAI CONSULTANTS
MAP 15318 I, -- i'\ -\.. •. I fl \ N '- 696O FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121-2974
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PHONE 858 558-6900 FAX 858 558-6159
FIGURE I AS - GRADED GEOLOGIC MAP DATE 05-16.2008
LADRILIONO
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WALL FOOTING
CONCRETE SLAB
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VISQUEEN .':- .,. .•
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*SEE REPORT FOR FOUNDATION WITDH AND DEPTH RECOMMENDATION -
WALL / COLUMN FOOTING DIMENSION DETAIL • GEOCON
• INCORPORATED . GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE SAN DIEGO, CALIFORNIA 92121- 2974
5 ' PHONE 858 558-6900 - FAX 858 5586159
58 FKJAML
VILLAGES OF LA COSTA - THE OAKS NORTH
LOT 81 -RECREATION AREA
• CARLSBAD, CALIFORNIA
DATE 05-16-2008- IPROJECT 0.06b05-52-20 -FIG.2 . COLFOOTZDWG/o,,I U-
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GEOCON VILLAGES OF LA COSTA THE OAKS NORTH ay 11' INCORPORATED LOT 81 RECREATION AREA GEOTECHNICAL CONSULTANTS
CARLSBAD CALIFORNIA - 6960 FLANDERS DRI\E - SAN DIEGO, CALIFORNIA 92121-2974
S PHONE 858 558-6900 - FAX 858 558-6159 A ••
AE / AML DATE 05 16 2008 PROJECT NO.06105 52 20 FIG 3 . RWO
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, TABLE
SUMMARY OF FIELD DENSITY TEST RESULTS
• Elev. Plus Field .Field Field, Rçq'd.
or 3/4" Adj. Adj. Dry Moist. Rel. Rel.
Depth Cuve Roëk MDD OMC Dens. Cont. Comp. Comp.
Test No. Date Location (ft) No: (%) (pc (%) (pcf) (%) (%) (%)
710 08/16/06 Unit Rec Area; Lot 81 . 438 4 50 138.4 7.5 125.1 8.7 90 90
711 08/16/06 Unit Rec Area; Lot 81 442 4 50 138.4 7.5 125.8 9.4 91 90
712 08/16/06 Unit Rec Area; Lot 81 447 4 40 136.0 8.4 122.3 9.2 90 90
716 08117/06 Unit Rec Area; Lot 81 445 4 30 133.5 9.2 124.7 9.9. 93 90
717 08/17/06 Unit Rec Area; Lot 81 . 450 4 30 133.5 9.2 125.9 10.4 94 90
718 08/17/06 Unit Rec Area; Lot 81 455 4 30 133.5 9.2 , 123.0 9.3 92 90
1205 10/30/06 Unit Rec Area; Lot 81 453 18 20 141.5 6.8 128.5 7.0 91 90
1208 10/31/06. Unit Rec Area; Lot 81 455 18 40 144.1 6.0 132.8 6.1 92 90
1209 10/31/06 Unit Rec Area; Lot 81 452 18 30 142.8 6.4 129.0 7.1 90 90
1210 10/31/06 Unit Rec Area; Lot 8l .. . 448 ,. 18 30 -142.8 6.4 128.7 6.5 90 .90
1211 10/31/06 UnitRec Area; Lot 8l 451 18 30 142.8 6.4 134.2 9.1 94 90
1212 10/31/06 .UnitRec,Area; Lot 8l . 455 18 10 140.2 7.2 127.7 9.8 -91 90
1213 10/31/06 Unit Rec Area; Lot 8l . 460 • 18 20 141.5 6.8 127.9 7.7 90 90
1214 .10/31/06 Unit, Rec Area; Lot 8l . 457 18 40 144.1 6.0 134.7 6.5 93 90
1238 1.1/07/06 UnitRecArea; Lot 81 438 18 20 141.5 6.8 129.4 8.1 - 91 .90 • -
1254 11/13/06 iJnitRec Area; Lot 81 - • .. . - 447 18 20 141.5 6.8 130.3. 6.7 - 92 . 90
SZ 1276 11/15/06 Unit Rec Area; Lot 81 - 462 3 10 131.2 8.8 118.7 - 10.1 - .90 90
SZ 1277 -11/15/06 Unit Rec Area; Lot 81 467 4 0 126.0 12.0 117.2 • 14.2 93 . -90
Si 1278 11/15/06 UnitRecArea;Lot81 - 473
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4 30 133.5 - 9.2 , 122.5 11.1 92 90
• ST 1279 11/15/06 Unit Rec Area; Lot 81 .
r478 4 30 133.5 9.2 120.4 9.0 90 90
1295 • 11/17/06 Unit Rec Area; Lot 81 454 18 30 142.8 6.4 131.6 6.8 92 90
FO 1456 12/18/06 Unit Rec Area; Lot 81 . • 458 18 10 140.2 7.2 128.1 7.5 91 90
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Project No. 06105-52-20 , - • .
May 16, 2008
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TABLE
- EXPLANATION OF CODED TERMS
-TEST SUFFIX . V
A, B, C.....Retest of previous density test failure, following moisture conditioning and/or recompaction.
- STRIKE-OUT -
Fill in area of density test failure was removed and replaced with properly compacted fill soil. --
- PREFIX CODE DESIGNATION FOR TEST NUMBERS
FG - FINISH GRADE . MT - MOISTURE TEST ST - SLOPE TEST
SZ - SLOPE ZONE
-CURVE NO.
Corresponds to curve numbers listed in the summary of laboratory maximum dry density and optimum moisture content test results table for
selected fill-soil samples encountered during testing and observation. V
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- ROCK CORRECTION
For density tests with rock percentage greater than zero, laboratory maximum dry density and optimum moisture content were adjusted for rock
content. For tests with rockcontent equal to zero, laboratory maximum dry density and optimum moisture content values are unadjusted.
- - TYPE OF TEST S V
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SC: Sand Cone Test (ASTM b1556)
NU: Nuclear Density Test (ASTM D2922) • . ..
OT: Other 5 S • .
- ELEVATION/DEPTH
Test elevations/depths have been rounded to the nearest whole foot. .
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Project No. 06105-52-20 V • S - May 16, 2008
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Sample No
Moisture Content (%) Dry Density (pci) Expansion Index Expansion Classification
Before Test After Test I
El AQ 7.6 13.1 118.7 0 - Very Low
Sample No , Description Maximum Dry Density (pci) Optimum Moisture
Content (% dry weight)
3 Dark brown Clayey, fine to coarse SAND 4-29.0 9.6
4 Grayish brown Clayey, fine to coarse SAND 126.0 11.0
18 Light reddish brown Silty to Clayey fine to coarse SAND 138 9 7.6
Sample No.'Dry Density (pci) Moisture Content (%) Unit Cohesion (psi) Angle of Shear Resistance (degrees)
4 1143 ilL 490 38
Sample No. - .Water-Sluble Sulfate (%)' Sülfat Exposure .
Jv
EI-AQ ' 0.006 . Negligible '
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- TABLE VI
. •SUMMARY OF FINISH-GRADE EXPANSION INDEX TEST RESULTS LOT 81 - RECREATION AREA .
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. VILLAGES OF LA COSTA —THE OAKS NORTH. .
-• NEIGHBORHOOD 3.2
- •i.••••S•••S•ç•i•Q••Sii•••SS•iS••i••SS••Q••.
TABLE V .
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
- CALIFOR NIA TEST NO. 4,117 -
Sample Location Sample at Finish-grade Expansion Index Expansion Classification
.0 Very Low Lot 81 . EIAQ -,