2005-9280 CN/G � -j j GEOTECHNICAL EXPLORATION, INC.
r
SOIL&FOUNDATION ENGINEERING - GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT - ENGINEERING GEOLOGY
A /
July 15, 2005
Job No. 04-8710
Dr, and Mrs. John Cowan
C/o Pacific Renovation
P.O. Box 816
Cardiff by The Sea, CA 92007
Attn. Mr. Jonathan House
Subject: Completion of Gradina Observation, Soil Testina and
Geotechnical Enaineerina
Building Pad Cowan Proposed Residence
1371 San Elijo,
Cardiff by the Sea, California
Dear Dr. and Mrs. Cowan:
As requested by Mr. Jonathan House, of Pacific Renovation, Geotechnical
Exploration, Inc., hereby confirms that rough grading for the building pad area at
the subject property has been completed. A report detailing our soil related work
and soil test results, as well as our conclusions and recommendations concerning
the subject project is in preparation. The report will be issued in the next few
weeks. A representative of our firm observed the recent rough grading operation
and tested the fill soils that were removed and recompacted during the preparation
of the building pad area of your property.
The completed grading in the building pad area consisted of removing and
recompacting on-site soils to a maximum depth not exceeding approximately 3 ft.
from finish pad subgrade. The grading was observed and/or tested between July 7
and July 8, 2005. All test results in the recompacted fill yielded relative compaction
results of at least 95 percent of maximum dry density of the soil determined per
ASTM DD1557-98. The on site soils have a low expansion potential.
7420 TRADE STREET - SAN DIEGO, CA 92121 - (858)549-7222 - FAX: (858)549-1604 - E-MAIL:geotech @ixpres.com
,0311342005 11:15 8585491604 GEI PAGE 02
GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
r HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
11 March 2005
J.E. Zane Construction Company MAY 2 6 2005 Job No. 04-8710
6507 Easy Street
Carlsbad, CA 92009 --
Attn: Mr. Joel Zane
Subject: Grading Plan Review and Rgsoonse to City's Thud Party Review
Proposed Cowan Residence
1371 San Elijo
Encinitas, California
Dear Mr. Zane:
As requested, we have reviewed the Grading Plan for the proposed project, and
also addressed the comments by the City's Third Party Review (Geopacific Inc.) of
drawing No. 9280 GR, Case No. 04-167, dated February 1, 2005. In general, we
have found the grading plans to be in general compliance with the intent of our
recommendations. However, we present some comments applicable to the
pertinent parts of the soil-foundation related aspects. Regarding the City of
Encinitas geotechnical consultant (Geopacific, Inc.) comments, we also present our
response comments.
Geopacific Inc.'s review requires supplemental data/information and or professional
clarification/statements from the project consultants, as follows:
1. Document 1, the preliminary geotechnical report, dated July 27, 2004, is a
Xerox copy, missing Figure II (Plot Plan), and appendices. Please provide a
clean copy of the report or a complete copy of Figure II.
GEI Response: A new copy of the preliminary geotechnical report, dated July
27, 2004, is attached herewith.
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858),549-1604 • E-MAIL: geotech@ixpres.com
,03+/13/.2095 11:15 8585491604 GEI -- PAGE 03
Proposed Cowan Residence Job No. 04-8710
Encinitas, California Page 2
2. ''The maximum depth of exploration reported in document 1 is 3 feet. Based
on document 2, base of foundation excavations after cut removal appears
will be greater than 4 or 5 feet. Please provide clarification as necessary".
GEI Response: The soil exploratory excavations were stopped after
observing the soils in the excavation at a shallow depth from the existing
surface confirmed that dense terrace materials had been encountered below
the topsoil layer. Since the topsoil layer will be removed and the building
pad has a cut/fill transition line, as shown in the grading plans (document 2),
we recommend that either the grading excavation provide approximately 1
foot of fill under the house foundations or that, after topsoil removal, the fill
portion be compacted to at least 95 percent of maximum dry density. If the
first option is chosen, the excavation will require approximately 21/2 feet of fill
under the pad finish subgrade elevation, or 1 foot underneath the footing
bottom. If the second option is chosen, all footing excavations will need to
be taken to firm terrace material, and the slab will be placed part on terrace
soils and part on fill compacted to at least 95 percent of maximum dry
density.
3. "Based on review of document 1, there is no list of references and appears
that document 2 has not been provided to the geotechnical consultant for
review. Please provide a geotechnical letter/report to address document 2".
GEI Response: We received the grading plan (document 2) for review after
the foundation plans were reviewed. Herein, we address our comments on
the reviewed grading plans.
4. "Retaining walls and excavations are depicted on document 2 along the
property boundaries. Please assess potential impact to adjacent properties
and provide mitigation remedial measurements as and if necessary."
464
.03,/13/.20FJ5 11:15 8585491604 GEI _. PAGE 04
Proposed Cowan Residence Job No. 04-8710
Encinitas, California Page 3
GEI Response: In areas where retaining walls require cuts up to 5 feet in
height, including footing thickness for the wall, only the upper 1 foot of soil is
supposed to be of loose relative compaction. Because of the height of the
needed cut to build the retaining walls, the contractor may, for safety
purposes only, ask for permission from the adjacent property owner to make
a temporary cut extending into the adjacent property and encroaching a
distance of no more than the 21/2 feet behind the back face of the retaining
wall or build a poured in place wall with slot vertical cuts extending no more
than 8 feet in length, leaving every other slot location uncut until the open
sections receive retaining walls. A third option would consist of using a
soldier pile and lagging retaining wall. It will be up to the general contractor
to decide which option to use. Before construction of the wall starts, removal
and recompaction of at least the 1-foot-thick topsoil layer is required before
any foundation excavations for the retaining walls are made. Very narrow
excavation voids left behind the retaining walls may be backfilled with '/z-inch
pea gravel.
5. "Will emplacements of back drains for retaining walls require encroachment
onto the adjacent properties? Please clarify".
,GEI Response: The back drain may be placed against the excavation vertical
or steep cut made at the property line if it consists of geocomposite such as
Miradrain 6000 with Quickdrain at the bottom (or equivalent). Another
option would consist of providing weep holes no farther than 5 feet apart in
the retaining walls (and above the elevation of the lower adjacent finish
grade) and protecting the walls with geofabric such as Mirafi 140 N. If the
contractor obtains written permission from the adjacent property owner, an
inclined temporary cut may be made to place a conventional perforated
subdrain system behind the retaining walls.
454
.0 VIV20.05 11:15 858549160 GEI PAGE 05
Proposed Cowan Residence Job No. 04-8710
Encinitas, California Page 4
6. "The project plans depict two cut/fill transition across the building pad. The
document 1 does not provide a clear recommendation regarding mitigation.
Please provide clarification'.
GEI Response: In numeral 2 of this letter, we discussed the options the
contractor has to take care of the cut/fill transition lines on the building pad
area.
Regarding the grading plans, the only comment that we have, in addition to the
subject discussed before in this letter, is that flow lines be also shown around the
east side of the proposed house to indicate that runoff shall drain away also from
that side of the house. Because the exterior grade is equal to the house finish pad
elevation, there is a potential for soil moisture intrusion inside the house. Drainage
flow lines should be shown on the grading plan and should provide gradient of at
least 5 percent away from the house in the nearest 2 feet. We also recommend
that this letter be incorporated as part of the grading plan specifications together
with the report dated July 27, 2004. After the discussed correction has been made,
the reviewed plans, in our opinion, are in general conformance with the
recommendations presented in our report dated July 27, 2004.
LIMITATIONS
The findings, opinions and recommendations presented herein have been made in
accordance with current generally accepted principles and practice in the field of
geotechnical engineering in the City of Encinitas. No warranty, either expressed or
implied, is made.
•03J13/20.05 11:15 858549160„1 GEI PAGE 06
Proposed Cowan Residence Job No. 04-8710
Encinitas, California Page 5
If you have any questions, please contact our office. Reference to our lob No. 04-
8710 will help expedite a response to your inquiry.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC. Q%()f ESS/0
A. Ce� ��F�
Cej
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R.C.E. 34422/G.E. 2007 Exp.`/33t
Senior Geotechnical Engineer 11
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cc: Dr. and Mrs. Cowan, and Pasco Engineering F OF
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�IAY 2 6 2005 �
REPORT OF PRELIMINARY GEOTECHNICAL
INVESTIGATION
Proposed Refold Residence
Between 1367 and 1375 San Elijo Avenue
Cardiff, California
JOB NO. 04-8710
27 July 2004
Prepared for:
Mr. Jay Refold
r
�rlr'�E11 GEOTECHNICAL EXPLORATION, INC.
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SOIL&FOUNDATION ENGINEERING • GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
27 July 2004
Mr. Jay Refold Job No. 04-8710
E.M. BRYLOR COMPANY
132 N. El Camino Real, Suite 295
Encinitas, CA 92024
Subject: Report of Preliminary Geotechnical Investigation
Proposed Refold Residence
Vacant Lot located between 1367 and 1375 San Elijo Avenue
Cardiff, California
Dear Mr. Refold:
In accordance with your request, and our proposal of June 24, 2004, Geotechnical
Exploration, Inc, has prepared this report of geotechnical investigation for the
subject site. The field work was performed on July 9, 2004.
In our opinion, if the conclusions and recommendations presented in this report are
implemented during site preparation, the site will be suited for the proposed
residential structure and improvements.
This opportunity to be of service is sincerely appreciated. Should you have any
questions concerning the following report, please do not hesitate to contact us.
Reference to our Job No. 04-8710 will expedite a response to your inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
Wm. D. Hesp er, G.E. Leslie D. Ree , President
R.C.E. 26222/G.E. 396 C.E.G. 999[exp. 3-31-05]/R.G. 3391
Senior Geotech Engineer
QPV%D Fi A! ,
co
W No.396
Exp. 3/31/2006
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F�FCAUE�� OFF CE��'c'`
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL:geotech @ixpres,com
TABLE OF CONTENTS
PAGE
I. PROJECT SUMMARY 1
II. SITE DESCRIPTION 2
III. FIELD INVESTIGATION 3
IV. SOIL DESCRIPTION 3
V GROUNDWATER 4
VI. LABORATORY TESTS AND SOIL INFORMATION 6
VII. CONCLUSION AND RECOMMENDATIONS 7
VIII. GRADING NOTES 21
IX. LIMITATIONS 22
FIGURES
I. Vicinity Map
II. Plot Plan
IIIa-d. Excavation Logs
Iva-b. Laboratory Test Results
V. Retaining Wall Drainage Schematic
VI. Foundation Requirements Near Slopes
APPENDICES
A. Unified Soil Classification System
B. General Earthwork Specifications
GH
REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
Proposed Refold Residence
Between 1367 and 1375 San Elijo Avenue
Cardiff; California
Job No. 04-8710
The following report presents the findings and recommendations of Geotechnical
Exploration, Inc. for the subject project (for project location see Figure No. I).
I. PROJECT SUMMARY
It is our understanding, based on communications with Mr. Jay Refold and Mr. Joel
Zane, that it is proposed to develop the existing residential site to receive a new
single-family residence with an attached garage, swimming pool and associated
improvements (see Figure No. II for Plot Plan). The proposed structure is to be a
maximum of two stories in height and is to be constructed of standard-type building
materials utilizing a concrete slab-on-grade foundation system.
Our investigation revealed that the site is underlain by dense terrace deposit
formational materials overlain with less than 2 feet of loose to medium dense fill soil
and topsoil materials. These variable density, shallow fill/topsoil materials will not
provide a stable soil base for the proposed structure and associated improvements.
As such, we recommend that these surficial soils be removed, scarified and
recompacted to a depth of approximately 1 to 2 feet as part of site preparation
prior to the addition of any new fill or structural improvements.
With the above in mind, the Scope of Work is briefly outlined as follows:
1. Identify and classify the surface and subsurface soils in the area of the
proposed construction, in conformance with the Unified Soil Classification
System (refer to Appendix A and Figure No. III).
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Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 2
2. Recommend site preparation procedures.
3. Recommend the allowable bearing capacities for the on-site dense natural
soils or properly compacted fills.
4. Evaluate the settlement potential of the bearing soils under the proposed
structural loads.
S. Recommend preliminary foundation design information and provide active
and passive earth pressures to be utilized in design of any proposed retaining
walls and foundation structures.
II. SITE DESCRIPTION
The property is known as Assessor's Parcel No. 260-620-68-00, Lot 68 according to
Recorded Map No. 10996, in the City of Encinitas, County of San Diego, State of
California.
The rectangular-shaped site, consisting of approximately 7,454 square feet, is
located between 1367 and 1375 San Elijo Avenue in the Cardiff area of the City of
Encinitas. The property is a "flag" lot bordered on the north by a two-story, single-
family residence at a slightly lower elevation; on the south by a single-story, single-
family residence approximately 6 feet lower in elevation; on the east by a two-
story, single-family residence approximately 4 feet higher in elevation; and on the
west by a westerly-facing slope and retaining wall, a two-story, single-family
residence approximately 8 feet lower in elevation, and the north-south trending San
Elijo Avenue. The property is accessed by an east-west trending, easterly
ascending, asphalt concrete driveway along the south side of the property to the
Orr
i
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 3
west addressed as 1367 San Elijo Avenue. No structures currently exist on the
property. The lot was cleared of all vegetation prior to our field work at the site.
The property consists of a relatively level building pad with a gentle slope to the
west. Elevations across the property range from approximately 123 feet above
mean sea level (MSL) along the east perimeter of the property to 114 feet above
MSL along the west perimeter of the property. Survey information concerning
approximate elevations across the site was obtained from a topographic survey map
prepared by Baker Land Surveying, Inc., dated July 7, 2004.
III. FIELD INVESTIGATION
Four exploratory handpits were placed on the site in areas where the proposed
structure and improvements are to be located and in order to obtain representative
soil samples to define the soil profile across the property. The soil in the
exploratory handpits was logged by our field representative, and samples were
taken of the predominant soils throughout the field operation. Excavation logs have
been prepared on the basis of our observations and the results have been
summarized on Figure No. III. The predominant soils have been classified in
conformance with the Unified Soil Classification System (refer to Appendix A).
IV. SOIL DESCRIPTION
Our investigation and review of pertinent geologic maps and reports indicate that
medium dense to dense formational marine terrace deposits underlie the entire site.
The encountered soil profile consists of less than 2 feet of fill soils/topsoils overlying
the formational terrace deposits.
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 4
The encountered fill soil/topsoil consists of 1 to 2 feet of loose to medium dense,
dry, gray-brown, very silty, fine to medium sand with some roots. The surficial fill
soils/topsoils are considered to be of variable density, of very low expansion
potential, and not suitable in their current condition for bearing support. Refer to
Figure Nos. III and IV for details.
The fill soils/topsoil are underlain by dense terrace deposit formational material
consisting of brown to red-brown, silty, fine to medium sand. The formational
marine terrace soils are, in general, of very low expansion potential and have
excellent bearing strength characteristics. Refer to Figure Nos. III and IV for
details.
V. GROUNDWATER
No groundwater was encountered during the course of our field investigation and
we do not anticipate any significant groundwater problems to develop in the future,
if the property is developed as proposed and proper drainage is maintained.
It should be kept in mind that any required grading operations may change surface
drainage patterns and/or reduce permeabilities due to the densification of
compacted soils. Such changes of surface and subsurface hydrologic conditions,
plus irrigation of landscaping or significant increases in rainfall, may result in the
appearance of surface or near-surface water at locations where none existed
previously. The damage from such water is expected to be localized and cosmetic
in nature, if good positive drainage is implemented, as recommended in this report,
during and at the completion of construction.
On properties such as the subject site where dense, low permeability soils and/or
formational materials exist at shallow depths, even normal landscape irrigation
SHY.
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 5
practices or periods of extended rainfall can result in shallow "perched" water
conditions. The perching (shallow depth) accumulation of water on a low
permeability surface can result in areas of persistent wetting and drowning of
lawns, plants and trees. Resolution of such conditions, should they occur, may
require site-specific design and construction of subdrain and shallow "wick" drain
dewatering systems.
Subsurface drainage with a properly designed and constructed french drain system
will be required along with continuous back drainage behind any proposed lower-
level living area or garage walls, property line retaining walls, or any perimeter
stem walls for raised-wood floors where the outside grades are higher than the
crawl space grades. Furthermore, crawl spaces shall be provided with the proper
cross-ventilation to help reduce the potential for moisture-related problems.
It must be understood that unless discovered during initial site exploration or
encountered during site grading operations, it is extremely difficult to predict if or
where perched or true groundwater conditions may appear in the future. When site
fill or formational soils are fine-grained and of low permeability, water problems
may not become apparent for extended periods of time.
Water conditions, where suspected or encountered during grading operations,
should be evaluated and remedied by the project civil and geotechnical consultants.
The project developer and the homeowner, however, must realize that post-
construction appearances of groundwater may have to be dealt with on a site-
specific basis.
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Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 6
VI. LABORATORY TESTS AND SOIL INFORMATION
Laboratory tests were performed on selected soil samples in order to evaluate their
physical and mechanical properties and their ability to support the proposed
residential structure. The following tests were conducted on the sampled soils:
1. Moisture/Density Relations (ASTM D1557-98, Method A)•
2. Particle Size Analysis (ASTM D422-98)
Laboratory compaction values establish the optimum moisture content and the
laboratory maximum dry density of the tested soils. The relationship between the
moisture and density of remolded soil samples gives qualitative information
regarding soil compaction conditions to be anticipated during any future grading
operation. In addition, this relation helps to establish the relative compaction of
existing fill soils.
The particle size analysis aids in classifying the tested soils according to the Unified
Soil Classification System and provides qualitative permeability and shear strength
information.
The expansion potential of soils is determined, when necessary, utilizing the
Uniform Building Code Test Method for Expansive Soils (UBC Standard No. 29-2).
In accordance with the UBC (Table 18-1-B), potentially expansive soils are classified
as follows:
Or.4
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 7
EXPA751to N INDEX POTENTIAL EXPANSION
20 Very low
50 Low
90 Medium
LE:: 91 to 130 Hi h
Above 130 Very high
Based on our particle-size test results, our visual classification, and our experience
with similar soils, it is our opinion that the on-site fill soils/topsoil and terrace
materials have a very low expansion potential, with an expansion index of less than
20.
Based on laboratory test data, our observations of the primary soil types on the
project, and our previous experience with laboratory testing of similar soils, our
Geotechnical Engineer has assigned conservative values for friction angle,
coefficient of friction, and cohesion to those soils which will have significant lateral
support or bearing functions on the project. The assigned values have been utilized
in assigning the recommended bearing value as well as active and passive earth
pressure design criteria.
VII. CONCLUSIONS AND RECOMMENDATIONS
The following conclusions and recommendations are based upon the practical field
investigation conducted by our firm, and resulting laboratory tests, in conjunction
with our knowledge and experience with the soils in the Cardiff area of the City of
Encinitas.
Our investigation revealed the site is underlain at depth by dense terrace deposit
formational materials, with less than 2 feet of variable density fill soils/topsoils
encountered in the proposed building area. In their present condition, these
1
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 8
surficial fill soils/topsoils will not provide a stable base for the proposed structure
and improvements. As such, we recommend that these surficial soils be removed
to depths of approximately 1 to 2 feet, be scarified, moisture conditioned, and
recompacted as part of site preparation prior to the addition of any new fill or
structural improvements.
A. Preparation of Soils for Site Development
1. Previously existing vegetation has been removed. It appears that no
significant root systems from trees and shrubbery have been left in place.
2. In order to provide a uniform, firm soils base for the proposed structure and
major improvements, the existing variable density fill soils/topsoil located in
the proposed building and improvement areas, and extending for a distance
of at least 5 feet beyond the perimeter thereof (where possible), shall be
excavated to expose firm, native formational terrace soil, or as per the
indications of our field representative. This depth is expected to be
approximately 1 to 2 feet.
The excavated loose soils shall be cleaned of any debris and deleterious
materials, watered to the approximate optimum moisture content, placed
where needed to reach planned grades, and compacted to at least 90 percent
of Maximum Dry Density, in accordance with ASTM D1557-98 standards.
Any areas that are to support proposed improvements or retaining structures
should be prepared in a like manner.
We do not anticipate that medium or highly expansive clay soils will be
encountered during grading. Should such soils be encountered and used as
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 9
fill, however, they shall be scarified, moisture conditioned to at least 5
percent above optimum moisture content, and be compacted to at least 90
percent.
3. No uncontrolled fill soils shall remain on the site after completion of any
future site work. In the event that temporary ramps or pads are constructed
of uncontrolled fill soils, the loose fill soils shall be removed and/or
recompacted prior to completion of the grading operation.
4. Any buried objects, abandoned utility lines, or particular soft soil areas, etc.,
which might be discovered in the construction area, shall be removed and the
excavation properly backfilled with approved on-site or imported fill soils and
compacted to at least 90 percent of Maximum Dry Density.
5. Any backfill soils placed in utility trenches or behind retaining walls that
support structures and other improvements (such as patios, sidewalks,
driveways, pavements, etc.) shall be compacted to at least 90 percent of
Maximum Dry Density. Backfill soils placed behind retaining walls and/or
crawl space retaining walls shall be installed as early as the retaining walls
are capable of supporting lateral loads.
B. Desinn Parameters for Proposed Foundations
6. For preliminary foundation design of new footings, based on the assumption
that new footings will be placed at least 18 inches below lowest adjacent
grade, we provide a preliminary allowable soil bearing capacity equal to 2,500
pounds per square foot (psf). This applies to footings at least 15 inches in
width. For wider and/or deeper footings, the allowable soil bearing capacity
may be calculated based on the following equation:
SHE!
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Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 9
fill, however, they shall be scarified, moisture conditioned to at least 5
percent above optimum moisture content, and be compacted to at least 90
percent.
3. No uncontrolled fill soils shall remain on the site after completion of any
future site work. In the event that temporary ramps or pads are constructed
of uncontrolled fill soils, the loose fill soils shall be removed and/or
recompacted prior to completion of the grading operation.
4. Any buried objects, abandoned utility lines, or particular soft soil areas, etc.,
which might be discovered in the construction area, shall be removed and the
excavation properly backfilled with approved on-site or imported fill soils and
compacted to at least 90 percent of Maximum Dry Density.
5. Any backfill soils placed in utility trenches or behind retaining walls that
support structures and other improvements (such as patios, sidewalks,
driveways, pavements, etc.) shall be compacted to at least 90 percent of
Maximum Dry Density. Backfill soils placed behind retaining walls and/or
crawl space retaining walls shall be installed as early as the retaining walls
are capable of supporting lateral loads.
B. Design Parameters for Proposed Foundations
6. For preliminary foundation design of new footings, based on the assumption
that new footings will be placed at least 18 inches below lowest adjacent
grade, we provide a preliminary allowable soil bearing capacity equal to 2,500
pounds per square foot (psf). This applies to footings at least 15 inches in
width. For wider and/or deeper footings, the allowable soil bearing capacity
may be calculated based on the following equation:
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 10
Qa = 1200D+700W
where
"Qa" is the allowable soil bearing capacity (in psf);
"D" is the depth of the footing (in feet) as measured from the lowest
adjacent grade; and
"W" is the width of the footing (in feet).
The allowable soil bearing capacity may be increased one-third for analysis
including wind or earthquake loads. The maximum total allowable soil
bearing capacity for properly compacted fills or natural formation is 6,000
psf.
7. The passive earth pressure of the encountered natural-ground soils and any
properly compacted fill soils (to be used for design of shallow foundation and
footings to resist the lateral forces) shall be based on an Equivalent Fluid
Weight of 300 pounds per cubic foot. This passive earth pressure shall only
be considered valid for design if the ground adjacent to the foundations
structure is essentially level for a distance of at least three times the total
depth of the foundation.
8. A Coefficient of Friction of 0.40 times the dead load may be used to calculate
friction force between the bearing soils and concrete wall foundations or
structure foundations and floor slabs.
9. The following table summarizes site-specific seismic design criteria to
calculate the base shear needed for the design of the residential structure.
The design criteria was obtained from the California Building Code (2001
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Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 11
edition) and is based on the distance to the closest active fault and soil profile
classification.
Parameter Value Reference
Seismic Zone Factor, Z 0.40 Table 16-I
Soil Profile T,,-- S� Table 16-3
Seismic Coefficient, Ca 0.40Na Table 16-0
Seismic Coefficient, Cv 0.56N, Table 16-R
Near-Source Factor, Na 1.00 Table 16-5
Near-Source Factor, N„ 1.07 Table 16-T
Seismic Source T e B Table 16-U
10. Our experience indicates that, for various reasons, footings and slabs
occasionally crack, causing brittle surfaces such as ceramic tiles to become
damaged. Therefore, we recommend that all conventional shallow footings
and slabs-on-grade contain at least a minimum amount of reinforcing steel to
reduce the separation of cracks, should they occur.
10.1 A minimum of steel for continuous footings should include at least four
No. 4 steel bars continuous, with two bars near the bottom of the
footing and two bars near the top. A minimum clearance of 3 inches
shall be maintained between steel reinforcement and the bottom or
sides of the footing.
10.2 Isolated square footings should contain, as a minimum, a grid of three
No. 4 steel bars on 12-inch centers, both ways, with no less than three
bars each way.
10.3 Interior floor slabs should be a minimum of 4 inches actual thickness
and be reinforced with No. 3 bars on 24-inch centers, both ways,
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 12
placed at midheight in the slab. Slabs at the main floor level shall be
underlain by a 2-inch-thick layer of clean sand (S.E. = 30 or greater)
overlying a moisture retardant membrane over 2 inches of sand. Slab
subgrade soil shall be verified by a Geotechnical Exploration, Inc.
representative to have the proper moisture content within 48 hours
prior to placement of the vapor barrier and pouring of concrete.
We recommend the project Civil/Structural Engineer incorporate isolation
joints and sawcuts to at least one-fourth the thickness of the slab in any floor
designs. The joints and cuts, if properly placed, should reduce the potential
for and help control floor* slab cracking. It is recommended that concrete
shrinkage joints be placed no farther than approximately 20 feet, and also at
re-entrant corners. However, due to a number of reasons (such as base
preparation, construction techniques, curing procedures, and normal
shrinkage of concrete), some cracking of slabs can be expected.
NOTE: The project Civil/Structural Engineer shall review all reinforcing
schedules. The reinforcing minimums recommended herein are not to be
construed as structural designs, but merely as minimum safeguards to
reduce possible crack separations.
Based on our laboratory test results and our experience with the soil types on
the subject site, the dense natural soils and properly compacted fill soils
should experience differential angular rotation of less than 1/240 under the
recommended allowable loads. The maximum differential settlement across
the structure when founded on properly compacted fill or dense natural
formation should be on the order of 1 inch.
Proposed Refold Residence
Cardiff, California Job No. 04-8710
Page 13
11. As a minimum for protection of on-site improvements, it is recommended
that all nonstructural concrete slabs (such as patios, sidewalks, etc.), be
founded on properly compacted and tested fill or dense native formation and
underlain by 3 inches of leveling clean sand, with No. 3 bars at 18-inch
centers at the center of the slab, and contain adequate isolation and control
joints. The performance of on-site improvements can be greatly affected by
soil base preparation and the quality of construction. It is therefore
important that all improvements are properly designed and constructed for
the existing soil conditions. The improvements should not be built on loose
soils or fills placed without our observations and testing.
Any rigid improvements founded on the existing loose surface soils can be
expected to undergo movement and possible damage and is therefore not
recommended. Geotechnical Exploration, Inc. takes no responsibility for
the performance of the improvements built on loose or inadequately
compacted fills. Any exterior area to receive concrete improvements shall be
verified for compaction and moisture within 48 hours prior to concrete
placement.
For exterior slabs with the minimum shrinkage reinforcement, control joints
shall be placed at spaces no farther than 15 feet apart or the width of the
slab, whichever is less, and also at re-entrant corners. Control joints in
exterior slabs shall be sealed with elastomeric joint sealant. The sealant shall
be inspected every 6 months and be properly maintained.
12. Driveway pavement, consisting of Portland cement concrete at least 51/2
inches in thickness, may be placed on properly compacted subgrade soils.
The concrete shall be at least 3,500 psi compressive strength, with control
joints no farther than 15 feet apart. Pavement joints shall be properly sealed
_"SFM
1
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 14
with the permanent joint sealant, as required in sections 201.3.6 through
201.3.8 of the Standard Specifications for Public Work Construction, 2003
Edition. Depending upon the lateral slab support of the drive, restraining
steel dowels may be required in areas that are not sufficiently restrained.
Subgrade soil for the driveway shall be compacted to at least 90 percent of
Maximum Dry Density.
13. If a swimming pool is planned, the swimming pool shall be founded entirely in
cut formational terrace soils. The soils surrounding the swimming pool shall
be of low-expansion potential.
The swimming pool deck area shall be provided with adequate surface
drainage including positive surface drainage and/or functional area drains. In
addition, the control and isolation joints shall be sealed with elastomeric joint
sealant. The sealant shall be inspected and maintained periodically by the
owner.
C. Floor Slab Va or Transmission
14. Vapor moisture transmission through floor slabs can cause problems 'for
moisture-sensitive flooring materials. The common practice in Southern
California is to place vapor retarders made of PVC, or of polyethylene. PVC
retarders are made in thickness ranging from 10- to 60-mil. Polyethylene
retarders, called visqueen, range from 5- to 10-mil in thickness. The thicker
the plastic, the stronger the resistance against puncturing.
15. Although polyethylene (visqueen) products are most commonly used,
products such as Vaporshield possess much higher tensile strength and are
more specifically designed for and intended to retard moisture transmission
Proposed Refold Residence
Cardiff, California Job No. 04-8710
Page 15
into concrete slabs. The use of Vaporshield or equivalent is highly
recommended when a structure is intended for moisture-sensitive floor
coverings or uses.
16. The vapor retarders need to have joints lapped and sealed with mastic or
manufacturer's recommended tape for additional protection. To provide
some protection to the moisture retarder, a layer of at least 2 inches of clean
sand on top and 2 inches at the bottom shall also be provided. No heavy
equipment, stakes or other puncturing instruments shall be used on top of
the liner before or during concrete placement. In actual practice, stakes are
often driven through the retarder material, equipment is dragged or rolled
across the retarder, overlapping or jointing is not properly implemented, etc.
All these construction deficiencies reduce the retarder's effectiveness.
17. The vapor retarders are not waterproof. They are intended to help prevent
or reduce capillary migration of vapor through the soil into the pores of
concrete slabs. Other waterproofing systems must supplement vapor
retarders if full waterproofing is desired. The owner should be consulted to
determine the specific level of protection required.
D. Retaining Walls
18. The active earth pressure (to be utilized in the design of any cantilever
retaining walls, utilizing on-site or imported very low expansive to low
expansive soils [EI less than 50] as backfill) shall be based on an Equivalent
Fluid Weight of 38 pounds per cubic foot (for level backfill only). For
2.0:1.0 sloping backfill, the equivalent fluid weight shall be not less than 52
pcf utilizing low expansive backfill. Any on-site clayey soils shall not be used
as wall backfill material, except as capping material in the upper 1 foot.
r
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 16
In the event that a retaining wall is to be designed for a restrained condition
(such as for basement retaining walls), a uniform pressure equal to 8xH
(eight times the total height of retained soil, considered in pounds per square
foot) shall be considered as acting everywhere on the back of the wall in
addition to the design Equivalent Fluid Weight. The soil pressure
produced by any footings, improvements, or any other surcharge placed
within a horizontal distance equal to the height of the retaining portion of the
wall shall be included in the wall design pressure.
Any loads placed on the active wedge behind the wall shall be included in the
design by multiplying the' load weight by a factor of 0.32. For restrained
walls, use a factor equal to 0.52. The retaining wall and/or building retaining
wall plans shall indicate that the walls shall be backfilled with very low to low
expansive soils (EI=less than 50).
19. Proper subdrains and free-draining backwall material or geofabric drainage
shall be installed behind all retaining walls (in addition to proper
waterproofing) on the subject project. Geotechnical Exploration, Inc. will
assume no liability for damage to structures or improvements that is
attributable to poor drainage. The architectural plans shall clearly indicate
that subdrains for any lower-level walls shall be placed at an elevation at
least 1 foot below the bottom of the lower-level slabs. At least 0.5-percent
fall shall be provided for the subdrain. The subdrain shall be placed in an
envelope of crushed rock gravel up to 1 inch in maximum diameter, and be
wrapped with Mirafi 140N filter or equivalent (see Figure No. V).
'54
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 17
E. Slopes
20. A representative of Geotechnical Exploration, Inc. must observe any
steep temporary slopes during construction. In the event that soils and
formational material comprising a slope are not as anticipated, any required
slope design changes would be presented at that time.
21. Where not superseded by specific recommendations presented in this report,
trenches, excavations and temporary slopes at the subject site shall be
constructed in accordance with Title 8, Construction Safety Orders, issued by
Cal-OSHA.
22. The soils that occur within the proximity of the rim or face of even properly
compacted fill or dense natural ground cut slopes often possess poor lateral
stability. The degree of lateral and vertical deformation depends on the
inherent expansion and strength characteristics of the soil types comprising
the slope, slope steepness and height, loosening of slope face soils by
burrowing rodents, and irrigation and vegetation maintenance practices, as
well as the quality of compaction of fill soils. Structures and other
improvements could suffer damage due to these soil movement factors if not
properly designed to accommodate or withstand such movement.
23. Rigid improvements such as top-of-slope walls, columns, decorative planters,
concrete flatwork, swimming pools and other similar types of improvements
can be expected to display varying degrees of separation typical of
improvements constructed at the top of a slope. The separations result
primarily from slope top lateral and vertical soil deformation processes.
These separations often occur regardless of being underlain by cut or fill
64 Ilk M
Proposed Refold Residence
Cardiff, California Job No. 04-8710
Page 18
slope material. Proximity to a slope top is often the primary factor affecting
the degree of separations occurring.
Typical and to-be-expected separations can range from minimal to up to 1
inch or greater in width. In order to minimize the effect of slope-top lateral
soil deformation, we recommend that the top-of-slope improvements be
designed with flexible connections and joints in rigid structures so that the
separations do not result in visually apparent cracking damage and/or can be
cosmetically dressed as part of the ongoing property maintenance. These
flexible connections may include "slip joints" in wrought iron fencing, evenly
spaced vertical joints in block walls or fences, control joints with flexible
caulking in exterior flatwork improvements, etc.
In addition, use of planters to provide separation between top-of-slope
hardscape such as patio slabs and pool decking from top-of-slope walls can
aid greatly in reducing cosmetic cracking and separations in exterior
improvements. Actual materials and techniques would need to be
determined by the project architect or the landscape architect for individual
properties. Steel dowels placed in flatwork may prevent noticeable vertical
differentials, but if provided with a slip-end they may still allow some lateral
displacement.
24. Shallow footings of proposed structures, walls, fences, swimming pools, etc.,
when founded 8 feet and farther away from the top of slopes, may be of
standard design in conformance with the recommended load-bearing value.
If the proposed foundations and footings are located closer than 8 feet inside
the top of slopes, they shall be deepened to 1.5 feet below a line beginning
at a point 8 feet horizontally inside the slopes and projected outward and
1
Proposed Refold Residence
Cardiff, California Job No. 04-8710
Page 19
downward, parallel to the face of the slope and into firm soils (see Figure No.
VI).
F. Site Drainage Considerations
25. Adequate measures shall be taken to properly finish-grade the building site
after the structures and other improvements are in place. Drainage waters
from this site and adjacent properties are to be directed away from the
foundations, floor slabs, footings, and slopes, onto the natural drainage
direction for this area or into properly designed and approved drainage
facilities. Roof gutters and downspouts should be installed on the structure,
with the runoff directed away from the foundations via closed drainage lines.
Proper subsurface and surface drainage will help minimize the potential for
waters to seek the level of the bearing soils under the foundations, footings
and floor slabs. Failure to observe this recommendation could result in
undermining and possible differential settlement of the structure or other
improvements on the site or cause other moisture-related problems.
Currently, the Uniform Building Code requires a minimum 2-percent surface
gradient for proper drainage of building pads unless waived by the building
official. Concrete pavement may have a minimum gradient of 0.5-percent:
In addition, appropriate erosion control measures shall be taken at all times
during and after construction to prevent surface runoff waters from entering
footing excavations or ponding on finished building pad areas.
26. Planter areas, flower beds and planter boxes shall be sloped to drain away
from the foundations, footings, and floor slabs at a gradient of at least 5
percent within 5 feet from the perimeter walls. Any planter areas adjacent to
the buildings or surrounded by concrete improvements shall be provided with
Or�
Proposed Refold Residence
Cardiff, California Job No. 04-8710
Page 20
sufficient area drains to help with rapid runoff disposal. No water shall be
allowed to pond adjacent to the buildings or other improvements. Planter
boxes shall be constructed with a closed bottom and a subsurface drain,
installed in gravel, with the direction of subsurface and surface flow away
from the slopes, foundations, footings, and floor slabs, to an adequate
drainage facility. Sufficient area 'drains and proper surface gradient shall be
provided throughout the project. Roof gutter and downspouts shall be tied to
storm drain lines.
G. Genera/ Recommendations
27. Following placement of any concrete floor slabs, sufficient drying time must
be allowed prior to placement of floor coverings. Premature placement of
floor coverings may result in degradation of adhesive materials and loosening
of the finish floor materials.
28. In order to minimize any work delays at the subject site during site
development, this firm should be contacted 24 hours prior to any need for
observation of footing excavations or field density testing of compacted fill
soils. If possible, placement of formwork and steel reinforcement in footing
excavations should not occur prior to observing the excavations; in the event
that our observations reveal the need for deepening or redesigning
foundation structures at any locations, any formwork or steel reinforcement
in the affected footing excavation areas would have to be removed prior to
correction of the observed problem (i.e., deepening the footing excavation,
recompacting soil in the bottom of the excavation, etc.)
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 21
VIII. GRADING NOTES
Any required grading operations shall be performed in accordance with the General
Earthwork Specifications (Appendix B) and the requirements of the City of Encinitas
Grading Ordinance.
29. Geotechnical Exploration, Inc. recommends that we be asked to verify the
actual soil conditions revealed during site grading work and footing
excavation to be as anticipated in this "Report of Preliminary Geotechnical
Investigation" for the project. In addition, the compaction of any fill soils
placed during site grading work must be tested by the soil engineer. It is the
responsibility of the grading contractor to comply with the requirements on
the grading plans and the local grading ordinance. All retaining wall and
trench backfill that will support structures or rigid improvements shall be
properly compacted. Geotechnical Exploration, Inc. will assume no
liability for damage occurring due to improperly or uncompacted backfill
placed without our observations and testing.
30. It is the responsibility of the owner and/or developer to ensure that the
recommendations summarized in this report are carried out in the field
operations and that our recommendations for design of this project are
incorporated in the structural plans. We shall be provided with the
opportunity to review the project plans once they are available, to see that
our recommendations are adequately incorporated in the plans.
31. This firm does not practice or consult in the field of safety engineering. We
do not direct the contractor's operations, and we cannot be responsible for
the safety of personnel other than our own on the site; the safety of others is
the responsibility of the contractor. The contractor should notify the owner if
Proposed Refold Residence Job No. 04-8710
Cardiff, California Page 22
he considered any of the recommended actions presented herein to be
unsafe.
IX. LIMITATIONS
Our conclusions and recommendations have been based on all available data
obtained from our field investigation - and laboratory analysis, as well as our
experience with the soils and formational materials located in this area of Cardiff.
Of necessity, we must assume a certain degree of continuity between exploratory
excavations and/or natural exposures. It is, therefore, necessary that all
observations, conclusions, and recommendations be verified at the time grading
operations begin or when footing excavations are placed. In the event
discrepancies are noted, additional recommendations may be issued, if required.
The work performed and recommendations presented herein are the result of an
investigation and analysis that meet the contemporary standard of care in our
profession within the County of San Diego. No warranty is provided.
This report should be considered valid for a period of two (2) years, and is subject
to review by our firm following that time. If significant modifications are made to
the building plans, especially with respect to the height and location of any
proposed structures, this report must be presented to us for immediate review and
possible revision.
The firm of Geotechnical Exploration, Inc. shall not be held responsible for
changes to the physical condition of the property, such as addition of fill soils or
changing drainage patterns, which occur subsequent to issuance of this report and
the changes are made without our observations, testing, and approval.
C '6
Proposed Refold Residence
Cardiff, California Job No. 04-8710
Page 23
Once again, should any questions arise concerning this report, please feel free to
contact the undersigned. Reference to .our Job No. 04-8710 will expedite a reply
to your inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
Wm. D. He �er, .E. 4D7RP.-
Les , President
R.C.E. 26222/G.E. 396
Senior Geotechnical Engineer C.E.G. 999[exp. 3-31-051/R.G. 3391
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Refold Residence
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Job Name: Proposed Refold Residence
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Job Number: 04-8710
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�� Job Number: 04-8710
PASCO ENGINEERING, INC.
535 NORTH HIGHWAY 101, SUITE A
SOLANA BEACH, CA 92075
(858) 259-8212 WAYNE A. PASCO
FAX (858)259-4812
R.C.E. 29577
March 30, 2005 PE 1317
Parks& Recreation Department
City of Encinitas
505 So. Vulcan Avenue
Encinitas, CA 92024
To John Franken:
This letter is in response to your plan check comments concerning 1371 San Elijo Ave,
Encinitas, CA(Dwg. No. 9280-G) dated January 18, 2005. In those comments, your
recommendation was to hold back the driveway walls as to not obstruct future street
improvements of curb, gutter, and sidewalk along San Elijo Ave.
After a discussion with Masih Maher, we will not be proposing a revision to the existing
driveway grades. Consequently, the walls along the sides of the driveway will be
necessary. In the situation of a dedication along San Elijo Avenue in the future by the lot
to west, the walls on the sides of the driveway could be removed based on changes to the
existing driveway grades and other improvements along San Elijo Avenue.
Please call if you have any questions.
Regards,
`,n1
Brian Ardolmo I x�
Senior Designer " ' '
HYDROLOGY CALCULATIONS
For
JAY REFOLD AND DEBRA REFOLD
APN: 260-620-68
CITY OF ENCINITAS, CALIFORNIA
Prepared For
Jay Refold &Joel Zane
6507 Easy Street
Encinitas, CA 92024
PE 1317
rt! JAN 18 2005
Fs
PREPARED BY:
PASCO ENGINEERING, INC.
535 N. HIGHWAY 101, SUITE A
SOLANA BEACH, CA 92075
FE
(858)259-8212 OQRO
ti�Q� yN
E A.. p q �!�
DATE: 1\30\05
REVISED: Lu No. 29577 m
FXP.3131107
c�vl�
� �sP
GJ o
&& s
WAYNE PASCO, RCE 29577 DATE
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TABLE OF CONTENTS
SECTION
DISCUSSION...............................................................................A
CONCLUSION..............................................................................B
PRE-DEVELOPMENT HYDROLOGY CALCULATIONS.......................0
POST-DEVELOPMENT HYDROLOGY CALCULATIONS .....................D
GRASSY SWALE TREATMENT BMP FLOW BASED
CALCULATION...........................................................................E
APPENDIX.................................................................................F
Runoff Coefficients
Statement of Impervious Surface
Hydrology Map Rainfall Isopluvials
Hydrology Node Maps
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A. INTRODUCTION
The purpose of this report is to analyze and compare the storm water runoff produced
from a 100-year storm event in the pre- and post-developed condition of the San Elijo
Avenue Development proposed project site. The subject property is located at 1371 San
Elijo Avenue, Encinitas, California and is geographically located at N33°02'00"
E117°17'00" as shown below in the Vicinity Map. The project site is bound by entirely
by residential development and San Elijo Avenue to the east.
I .5
5
• I
t4
i
.Yi1T TJ JL.J_�
Pre-Developed Conditions
The existing condition of the project site consists of one vacant parcel at San Elijo
Avenue. The parcel consists of a graded pad with berms and vegetated cover. The north
and south side of the parcel is adjacent to single family residences. The east and west side
is adjacent to other single family residence. The site is gently sloped from east to west. A
3-foot and 4-foot high retaining wall to the east and west exists on neighbors property.
The retaining walls separate adjacent neighbors building pads from the proposed
development parcels building pad. The neighbors building pad to the east is 5 feet higher
than the proposed developed parcel. The neighbors building pad to the west is about 10
feet lower. An 11 foot wide ac paved private driveway, from San Elijo Avenue, serves
the residence. The driveway also serves an existing residence to the east and west. The
existing driveways maximum grade is 20%.
The site drains over a slope from east to west and then south to the existing paved
driveway. There is a small amount of runoff that exits the parcel at the northwest corner.
This runoff has eroded the slope of the westerly neighbor property and silt deposits are
present around the building pad. This runoff will be redirected to the proposed grassy
swale treatment bmp and eliminate the existing erosion that occurs today. Other drainage
sheet flows onto the parcel from uphill neighbors as shown on the hydrology node map
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(See Appendix). An on-site berm along the westerly boundary allows drainage to exit the
site onto the ac paved driveway. All drainage eventually reaches San Elijo Avenue. The
runoff coefficient used for existing conditions is 0.63 (based on Table 3-1 of the San
Diego County Hydrology Manual, See Appendix). The calculated existing 100-year peak
storm water runoff is 1.14 cfs.
Post- Development Conditions
The proposed project design consists of the construction of a new single family residence.
The existing 1 I foot wide ac paved driveway serving the residence will be widened to 20
feet. This driveway already serves another parcel to the east and west. Existing drainage
onto the site from the parcel to the east will be collected on-site in swales and directed to
a grassy swale treatment bmp along the westerly boundary. All other proposed runoff
from the site will be directed to the grassy swale treatment bmp. The grassy swale will be
used for flow based treatment. The proposed drainage facilities, to be constructed during
building construction will collect and convey drainage from the project site and discharge
in the same location as pre development conditions.
80'h percentile storm runoff produced by the developed site will be treated in a grass lined
swale along the westerly boundary as shown on the grading plans. The swale shall have
be I foot deep and 4 foot wide. The total length of the grassy swale treatment bmp will
accommodate the required flow based treatment. (See Section E)
The runoff coefficient used for proposed on-site conditions is 0.68 (based on calculation
for runoff coefficient as shown the San Diego County Hydrology Manual, See
Appendix). The calculated proposed 100-year peak storm water runoff is 1.18 cfs.
Methodology and Results
The hydrologic model used to perform the hydrologic analysis presented in this report
utilizes the Ration Method (RM) equation, Q=CIA. The RM formula estimates the peak
rate of runoff based on the variables of area, runoff coefficient, and rainfall intensity.
The rainfall intensity (I) is equal to:
I= 7.44 x P6 x D-0.641
Where:
I =Intensity(in/hr)
P6 = 6-hour precipitation(inches)
D = duration(minutes—use Tc)
Using the Time of Concentration (Tc), which is the time required for a given element of
water that originates at the most remote point of the basin being analyzed to reach the
point at which the runoff from the basin is being analyzed. The RM equation determines
the storm water runoff rate (Q) for a given basin in terms of flow (typically in cubic feet
per second (cfs) but sometimes as gallons per minute (gpm)). The RM equation is as
follows:
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Q = CIA
Where:
Q= flow (in cfs)
C = runoff coefficient, ratio of rainfall that produces storm water
runoff(runoff vs. infiltration/evaporation/absorption/etc)
I = average rainfall intensity for a duration equal to the Tc for the
area, in inches per hour.
A= drainage area contributing to the basin in acres.
The RM equation assumes that the storm event being analyzed delivers precipitation to
the entire basin uniformly, and therefore the peak discharge rate will occur when a
raindrop that falls at the most remote portion of the basin arrives at the point of analysis.
The RM also assumes that the fraction of rainfall that becomes runoff or the runoff
coefficient C is not affected by the storm intensity, I, or the precipitation zone number.
In addition to the above Ration Method assumptions, the conservative assumption that all
runoff coefficients utilized for this report are based on type"D" soils.
The pre and post-development runoff coefficients were calculated based upon the
methodologies presented in the June 2003 revision of the San Diego County Hydrology
Manual. The calculations used to determine the coefficients utilized in the hydrologic
model for the proposed project site are included in the appendix E of this report.
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B. CONCLUSION
Based on the information and calculations contained in this report it is the professional
opinion of Pasco Engineering, Inc. that the storm drain system as proposed on the
corresponding Grading Plan will function to adequately and safely intercept, contain and
convey Qloo to the appropriate points of discharge.
\\ServeNob files\Hydrology& Hydraulics\1317 HYDRO REPORT.doc
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C. PRE-DEVELOPMENT HYDROLOGY CALCULATIONS
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HYDROLOGY STUDY for COWAN RESIDENCE
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RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2001,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2002 Advanced Engineering Software (aes)
Ver. 1.5A Release Date: 01/01/2002 License ID 1452
Analysis prepared by:
Pasco Engineering Inc.
535 N. Hwy 101, Suite A
Solana Beach, Ca 92075
858-259-8212
************************** DESCRIPTION OF STUDY **************************
* Pre Development
* 100 Year Storm Calculations
**************************************************************************
FILE NAME: 1317.DAT
TIME/DATE OF STUDY: 14:57 01/05/2005
--------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.500
SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.85
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
*USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL*
HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING
WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR
NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)
2. (Depth)* (Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
FLOW PROCESS FROM NODE 3.00 TO NODE 2.00 IS CODE = 21
----------------------------------------------------------------------------
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA) :
USER-SPECIFIED RUNOFF COEFFICIENT = .6300
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH = 110.00
UPSTREAM ELEVATION = 139.00
DOWNSTREAM ELEVATION = 128.00
ELEVATION DIFFERENCE = 11.00
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URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 4.119
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
TIME OF CONCENTRATION ASSUMED AS 6-MINUTES
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.856
SUBAREA RUNOFF(CFS) = 0.59
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.59
FLOW PROCESS FROM NODE 2.00 TO NODE 1.00 IS CODE = 51
----------------------------------------------------------------------------
»»>COMPUTE TRAPEZOIDAL CHANNEL FLOW««<
»»>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)««<
ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 113.00
CHANNEL LENGTH THRU SUBAREA(FEET) = 210.00 CHANNEL SLOPE = 0.0714
CHANNEL BASE(FEET) = 4.00 "Z" FACTOR= 5.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 0.33
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.093
*USER SPECIFIED(SUBAREA) :
USER-SPECIFIED RUNOFF COEFFICIENT = .6300
S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.86
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.41
AVERAGE FLOW DEPTH(FEET) = 0.08 TRAVEL TIME(MIN.) = 1.45
Tc(MIN.) = 7.45
SUBAREA AREA(ACRES) = 0.17 SUBAREA RUNOFF(CFS) = 0.55
TOTAL AREA(ACRES) = 0.33 PEAK FLOW RATE(CFS) = 1.14
END OF SUBAREA CHANNEL FLOW HYDRAULICS:
DEPTH(FEET) = 0.10 FLOW VELOCITY(FEET/SEC.) = 2.63
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 1.00 = 320.00 FEET.
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 0.33 TC(MIN.) = 7.45
PEAK FLOW RATE(CFS) = 1.14
END OF RATIONAL METHOD ANALYSIS
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D. POST DEVELOPMENT HYDROLOGY CALCULATIONS
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****************************************************************************
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2001,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2002 Advanced Engineering Software (aes)
Ver. 1.5A Release Date: 01/01/2002 License ID 1452
Analysis prepared by:
Pasco Engineering Inc.
535 N. Hwy 101, Suite A
Solana Beach, Ca 92075
858-259-8212
************************** DESCRIPTION OF STUDY **************************
* Post Development
* 100 Year Storm Calculations
**************************************************************************
FILE NAME: 1317.DAT
TIME/DATE OF STUDY: 15:01 01/05/2005
------------------------------------------------------------------------
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
--------------------------------------------------------------------------
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.500
SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.85
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
*USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL*
HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING
WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR
NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150
GLOBAL STREET FLOW-DEPTH CONSTRAINTS:
1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)
2. (Depth)* (Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 2.00 IS CODE = 21
----------------------------------------------------------------------------
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA) :
USER-SPECIFIED RUNOFF COEFFICIENT = .6300
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH = 110.00
UPSTREAM ELEVATION = 139.00
DOWNSTREAM ELEVATION = 128.00
ELEVATION DIFFERENCE = 11.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 4.119
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*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
TIME OF CONCENTRATION ASSUMED AS 6-MINUTES
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.856
SUBAREA RUNOFF(CFS) = 0.59
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.59
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 1.00 IS CODE = 51
----------------------------------------------------------------------------
»»>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
»»>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)««<
ELEVATION DATA: UPSTREAM(FEET) = 128.00 DOWNSTREAM(FEET) = 113.00
CHANNEL LENGTH THRU SUBAREA(FEET) = 210.00 CHANNEL SLOPE = 0.0714
CHANNEL BASE(FEET) = 4.00 "Z" FACTOR = 5.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 0.33
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.101
*USER SPECIFIED(SUBAREA) :
USER-SPECIFIED RUNOFF COEFFICIENT = .6800
S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.88
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.44
AVERAGE FLOW DEPTH(FEET) = 0.08 TRAVEL TIME(MIN.) = 1.43
Tc(MIN.) = 7.43
SUBAREA AREA(ACRES) = 0.17 SUBAREA RUNOFF(CFS) = 0.59
TOTAL AREA(ACRES) = 0.33 PEAK FLOW RATE(CFS) = 1.18
END OF SUBAREA CHANNEL FLOW HYDRAULICS:
DEPTH(FEET) = 0.10 FLOW VELOCITY(FEET/SEC.) = 2.56
LONGEST FLOWPATH FROM NODE 3.00 TO NODE 1.00 = 320.00 FEET.
END OF STUDY SUMMARY:
TOTAL AREA(ACRES) = 0.33 TC(MIN.) = 7.43
PEAK FLOW RATE(CFS) = 1.18
END OF RATIONAL METHOD ANALYSIS
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HYDROLOGY STUDY for COWAN RESIDENCE
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E. GRASSY SWALE TREATMENT BMP CALCULATIONS
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Grassy Swale Treatment BMP
Cross Section for Triangular Channel
Project Description
Project File c:\haestad\academic\fmw\1317.fm2
Worksheet Grassy Swale Treatment BMP
Flow Element Triangular Channel
Method Manning's Formula
Solve For Discharge
Section Data
Mannings Coefficient 0.030
Channel Slope 2.0000 %
Depth 1.00 ft
Left Side Slope 2.000000 H :V
Right Side Slope 2.000000 H :V
Discharge 8.19 cfs
1.00 ft
1
VN
H 1
NTS
01/07/05 Academic Edition FlowMaster v5.17
04:28:15 PM Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1
Grassy Swale Treatment BMP
Worksheet for Triangular Channel
Project Description
Project File c:\haestad\academic\fmw\1317.fm2
Worksheet Grassy Swale Treatment BMP
Flow Element Triangular Channel
Method Manning's Formula
Solve For Discharge
Input Data
Mannings Coefficient 0.030
Channel Slope 2.0000 %
Depth 1.00 ft
Left Side Slope 2.000000 H :V
Right Side Slope 2.000000 H :V
Results
Discharge 8.19 cfs
Flow Area 2.00 ft2
Wetted Perimeter 4.47 ft
Top Width 4.00 It
Critical Depth 1.01 ft
Critical Slope 0.019119 ft/ft
Velocity 4.10 ft/s
Velocity Head 0.26 ft
Specific Energy 1.26 ft
Froude Number 1.02
Flow is supercritical.
01/07/05 Academic Edition FlowMaster v5.17
04:27:55 PM Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1
HYDROLOGY STUDY for COWAN RESIDENCE
PE 1317
80TH PERCENTILE DESIGN FLOW CALCULTION
Q=CIA
Where,
Q=Stormwater runoff design flow
C=runoff coefficient for DCIA, conservatively assumed as 0.95
1=8e percentile storm flow criteria, 0.16 inches per hour for San Diego County
A=DCIA(acres) = 0.1Oac
Q=(0.95)*(0.16 in/hr)*(O.I Oac)
Q=0.015cfs
GRASS SWALE SCOUR CALCULATION
v=0.20 ft/s (See Next Page) <1.0 ft/s checks okay for scour
TREATMENT SWALE CAPACITY CALCULATION
Q,..aY 8.19 cfs (See Next Page)
LENGTH OF TREATMENT SWALE
L=vt
Where,
L=Length of swale
v--velocity
t=ome (9 minute treatment time)
L=(0.20ft/s)(9min.)(60s/min.)
L=100ft minimum
Length of swale shown on plans is approximately 100ft (Checks Good)
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PE#1317 4:37 PM 1/7/2005
Grassy Swale Flow Based Calculation
Cross Section for Triangular Channel
Project Description
Project File c:\haestad\academic\fmw\1317.fm2
Worksheet 80th Percentile Calculation
Flow Element Triangular Channel
Method Manning's Formula
Solve For Channel Depth
Section Data
Mannings Coefficient 0.200
Channel Slope 2.0000 %
Depth 0.19 ft
Left Side Slope 2.000000 H :V
Right Side Slope 2.000000 H :V
Discharge 0.01500000 cfs
0.19 ft
1
V N
H 1
NTS
01/07/05 Academic Edition FlowMaster v5.17
04:30:56 PM Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1
Grassy Swale Flow-based Calculation
Worksheet for Triangular Channel
Project Description
Project File c:\haestad\academic\fmw11317.fm2
Worksheet 80th Percentile Calculation
Flow Element Triangular Channel
Method Manning's Formula
Solve For Channel Depth
Input Data
Mannings Coefficient 0.200
Channel Slope 2.0000 %
Left Side Slope 2.000000 H :V
Right Side Slope 2.000000 H :V
Discharge 0.01500000 cfs
Results
Depth 0.19 ft
Flow Area 0.07 ft2
Wetted Perimeter 0.86 ft
Top Width 0.77 ft
Critical Depth 0.08 ft
Critical Slope 1.969747 ft/ft
Velocity 0.20 ft/s
Velocity Head 0.65e-3 ft
Specific Energy 0.19 ft
Froude Number 0.12
Flow is subcritical.
01/07/05 Academic Edition FlowMaster v5.17
04:30:42 PM Haestad Methods,Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1
HYDROLOGY STUDY for COWAN RESIDENCE
PE 1317
F. APPENDIX
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CALCULATED RUNOFF COEFFICIENT :
C = 0.90 x(%IMPERVIOUS)+ Cp x (1% Impervious) (County Hydrology Manual)
POST DEVELOPMENT RUNOFF COEFFICIENT—PROJECT SITE:
C = 0.90 x (.69) +0.20 x (1-.69)
C = 0.68
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PE# 1317 4:37 PM 117/2005
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HYDROLOGY STUDY for COWAN RESIDENCE
PE 1317
STATEMENT OF IMPERVIOUS SURFACE
COWAN RESIENCE
TOTAL NEW IMPERVIOUS SURFACE= 1,400 SF
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ENGINEERING SERVICES DEPARTMENT
Capital Improvement Projects
City Of District Support Services
Encinitas Field Operations
Sand Replenishment/Stormwater Compliance
Subdivision Engineering
Traffic Engineering
November 28, 2006
Attn: Nationwide Mutual Insurance Company
P.O. Box 1820
La Mesa, California 91944
RE: Cowan, John and Kristi
1371San Elijo Avenue
APN 260-620-68
Grading permit 9280-G
Final release of security-labor and materials
Permit 9280-G authorized earthwork, storm drainage, and erosion control, all needed to
build the described project. The Field Operations Division has finaled the project.
Therefore, release of the security deposit is merited.
Performance Bond Bd 383803 in the amount of$29,388.74, is hereby fully
exonerated. The document original is enclosed.
Should you have any questions or concerns, please contact Debra Geishart at (760) 633-
2779 or in writing, attention this Department.
Sincerely,
Debra Geishart y Lembach
Engineering Technician inance Manager
Subdivision Engineering Financial Services
Cc: Jay Lembach,FinanceManager
Cowan,John and Kristi
Debra Geishart
File
Enc.
TEL 760-633-2600 / FAX 760-633-2627 505 S. Vulcan Avenue, Encinitas, California 92024-3633 TDD 760-633-2700 recycled paper
�►�I �I GEOTECHNICAL EXPLORATION, INC.
r �
SOIL&FOUNDATION ENGINEERING - GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT - ENGINEERING GEOLOGY
July 15, 2005
Job No. 04-8710
Dr. and Mrs. John Cowan
C/o Pacific Renovation
P.O. Box 816
Cardiff by The Sea, CA 92007
Attn. Mr. Jonathan House
Subject: Completion of Gradina Observation, Soil Testina and
Geotechnical Enaineerina
Building Pad Cowan Proposed Residence
1371 San Elijo,
Cardiff by the Sea, California
Dear Dr. and Mrs. Cowan:
As requested by Mr. Jonathan House, of Pacific Renovation, Geotechnical
Exploration, Inc., hereby confirms that rough grading for the building pad area at
the subject property has been completed. A report detailing our soil related work
and soil test results, as well as our conclusions and recommendations concerning
the subject project is in preparation. The report will be issued in the next few
weeks. A representative of our firm observed the recent rough grading operation
and tested the fill soils that were removed and recompacted during the preparation
of the building pad area of your property.
The completed grading in the building pad area consisted of removing and
recompacting on-site soils to a maximum depth not exceeding approximately 3 ft.
from finish pad subgrade. The grading was observed and/or tested between July 7
and July 8, 2005. All test results in the recompacted fill yielded relative compaction
results of at least 95 percent of maximum dry density of the soil determined per
ASTM DD1557-98. The on site soils have a low expansion potential.
7420 TRADE STREET - SAN DIEGO, CA 92121 - (858)549-7222 - FAX: (858)549-1604 - E-MAIL:geotech @ixpres.com
Job No.04-8710 Page No.2
Cowan Residence
We issue this letter so that foundation excavations and slab on grade in the building
pad area may continue.
All recommendations presented in our geotechnical investigation report for the
project remain applicable, unless superseded in writing by our firm.
LIMITATIONS
The findings and opinions presented herein have been made in accordance with
currently accepted principles and practice in the field of geotechnical engineering in
the City of Encinitas. No warranty, either expressed or implied, is made.
If you have any questions regarding this letter, please contact our off=ice. Reference
to our Job No.04-8710 will help expedite a response to your inquiry.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
CF9
Jaime A. Cerros, .E. CO
R.C.E. 34422/G.E.2007 No. 0020/07
Senior Geotechnical Engineer �\ � FQ g�3op � /
��F OF
,031131.200.5 11:15 8585491604 GEI PAGE 02
GEOTECHNICAL EXPLORATION, INC.
SOIL&FOUNDATION ENGINEERING • GROUNDWATER
HAZARDOUS MATERIALS MANAGEMENT • ENGINEERING GEOLOGY
li March 2005
I
J.E. Zane Construction Company I MAY 2 6 2005 .lob No. 04-8710
6507 Easy Street j
Carlsbad, CA 92009 �----- -
Attn: Mr. Joel Zane cEs
Subject: Grading Plan Review and Resuonse tQ City's Third Party Review
Proposed Cowan Residence
1371 San Elijo
Encinitas, California
Dear Mr. Zane:
As requested, we have reviewed the Grading Plan for the proposed project, and
also addressed the comments by the City's Third Party Review (Geopacific Inc.) of
drawing No. 9280 GR, Case No. 04-167, dated February 1, 2005. In general, we
have found the grading plans to be in general compliance with the intent of our
recommendations. However, we present some comments applicable to the
pertinent parts of the soil-foundation related aspects. Regarding the City of
Encinitas geotechnical consultant (Geopacific, Inc.) comments, we also present our
response comments.
Geopacific Inc.'s review requires supplemental data/information and or professional
clarification/statements from the project consultants, as follows:
1. Document 1, the preliminary geotechnica/ report, dated July 27, 2004, is a
Xerox copy, missing Figure II (Plot Plan), and appendices. Please provide a
clean copy of the report or a complete copy of Figure II.
GEI Response: A new copy of the preliminary geotechnica) report, dated July
27, 2004, is attached herewith.
7420 TRADE STREET • SAN DIEGO, CA 92121 • (858)549-7222 • FAX: (858)549-1604 • E-MAIL: geotech@ixpres.com