HomeMy WebLinkAboutCDP 99-32; JENSEN RESIDENCE; Hydrologic Analysis and Report Study; 2000-06-14OWEN ENGINEERING GROUP
Civil, Geotechnical and Structural Encintxrinc
June 14, 2000
Site: Proposed Residence
Parcel No. 1; Parcel Map Number 18236
Carlsbad, Califomia
Subject: Drainage Study and Report for Proposed Single Family
Residence
Reference: 1. Grading Plans (Sheet 2&3) Prepared by Hossein Zomorrodi; R.C.E
43235
Dear Sirs:
This report presents the results of our hydrologic analysis and drainage study for the
proposed residence located on Parcel Nxraiber 1,Parcel Map Number 18236, in the City
of Carlsbad Califomia.
The scope of our hydrologic analysis was to quantify drainage eminating from the site,
during a 50-year frequency rain event, analyzing the proposed drainage system for
capacity, and determining surface drainage flow direction.
This drainage study was performed utilizing methods of analyses that are outlined in the
County of San Diego Drainage Design Manual. Our analysis was based on topographical
and proposed finish grade information show on the current grading plan, prepared by
Hossein Zomorrodi, R.C.E 43235.
We have studied the grading plan and determined that four separate areas generate
surface drainage from the site ( See Site Plan). Based on review of the grading plans there
are two separate drainage systems consisting of 4-inch diameter P. V.C pipe that collect
and direct the majority of the drainage generated from the proposed building site. One
drainage system parallels the northem property line and the other exists along the
southem property line, both convey drainage towards the westem property boundary.
Drainage collected from these two systems will be directed into a proposed earthen
drainage swale, located at the northwest end of the subject property.
1525 Grand Ave, San Marcos, Califomia 92069 Telephone (760) 471 - 6000 Fax (760) 471-6096
14661 Myford Road, Suite C, Tustin, California 92806 Telephone (714) 734 - J993 Fax (714) 734-9732
CII r -i2
The earthen swale will be constmcted to direct drainage flows within a non-exclusive
drainage easement located at the southem property line. (See Accompanying Grading
Plan).
We have performed calculations to determine if the proposed drainage system is adequate
to convey flows generated from the 50-year rain event. Based on our calculations all
proposed drainage systems are adequate. All hydrologic and hydraulic calculations
performed for this study for are provided with this report.
The professional opinions presented in this report have been developed using that degree
of care and skill ordinarily exercised, under similar circumstances, by reputable civil
engineering and geotechnical consultants practicing in this-or similar localities. No other
warranty, expressed or implied, is made as to the professional advice included in this
letter.
Sincerely,
Owen Engineering Group
Charles J. Randle, PE
RCE 22096, CA
INTRODUCTION
This report summarizes the methods used and the issues encountered during the
Planning Study process. It also includes recommendations of the preferred alignments
along both Carlsbad Boulevard and Cannon Road. The limits of the roadways included
in the study are as follows:
CARLSBAD BLVD.- from 800' north of the intersection at Cannon Road southerly
to just south of Manzano Drive a distance of 3400'.
CANNON RD.- from the intersection at Carlsbad Blvd. easterly to just west of the
AT&SF railroad tracks a distance of 1200'.
The goal ofthis study is to provide engineering guidelines for the future improvement of
carlsbad Blvd. and Cannon Rd. The guidelines developed for these two streets should:
1) Ensure that the widened street will accommodate future traffic volumes and
tuming movements.
2) Recognize the importance of on-street parking.
3) Provide for pedestrian and bicycle safety.
4) Ensure that reasonable driveway access is maintained to serve the
properties fronting along Carlsbad Blvd.
1
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EXIST. EDGE 0F| PAVEMENT
FDR FUTURE STOECT IMPROVEMENT SEE DWO. f 331-7
CARLSBAD BOULEVARD
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INTENSITY-DUjV\TION DtiIGN CHART
TnTlTlllliitii i-i-'i'-*<M''','''''"'''"'m'f=''T ;-i" ilLiaa-Lidi-HirrifliT!i
i Equation; I = 7*44 P. D
I = Intensity (Zn./Hr.)
= 6 Hr. Precipitation (In.)
Directions for Application:
1) From precipitation naps determine 6 hr. and
24 hr. amounts for the selected frequency.
These maps are printed in the County Hydrology
Manual (10, 50 and 100 yr. maps included in the
Design and Procedure Manual).
2) Adjust 6 hr. precipitation (if necessary) so
that it is within the range of 45% to 65% of
the 24 hr. precipitation. (Not npplicable f ^
to Desert)
3) Plot 6 hr. precipitation on the right side
of the chart.
4) Draw a line through the point parallel to the
plotted lines.
5) This line is the intensity-duration curve for
the location being analyzed.
Application Form: .
0) Selected Frequency yr.
1) Pe ' • ^24" % " ^*
2) Adjusted *Pg= ^rZ^Q
3) t^ = min.
4) I = ^in/hr.
24
in.
*Not Applicable to Desert Region
40 50 1
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION 6-
FLOOD CONTROL 50-YEAR 6-
ISOPLUVIALS
HOU ^ PRECIPITATIOE^
OF 50-YEAR G-HOUR
PRECIPlTATiQM IM TOiTilS OF ftfi liJCH
NATIONAL OCEANIC AND AT
SPECIAL STUDIES BRANCH, OFFICE OFH
U.S. DEPARTMEr T OF COMMERCE
I., .. I I. I i 1.. . • i
COUNTY OF SAN DIEGO .
DEPARTMENT OF SANITATION $•
FLOOD CONTROL 50-YEAR 24-HOUR PRECIPITATION
30»
15'
33*
-ny ISOPLUVIALS
Pt*pa
ECIAL STUDIES DKANCII, OFFICE OF II
30*
VTUSIV
OF 50-YEAR 24-HOllR
PRECIPITATIOM IN TENTHS OF AN INCH
.-d by
U.S. DEPARTMEN P OF COMMERCE
NATIONAL OCEANIC AND AT^ OSPIIERIC ADMINISTRATION
DKOLOGY, NATIONAL WEATHER SERVICE
118" 30' \5' 117
RUNOFF COEFFICIENTS (R.'SLTIONAL METHOD)
LAND USE Coefficient,
Soil Group
C
(1)
A B C D
Undeveloped . 30 .35 .40 .45
Residential:
Rural . 50 . 35 .40 .45
Single Family .40 .45 .50 . 55
Multi-Units .45 .50 .60 . 70
Mobile Hemes (2) .45 .50 .55 .65
Commercial (2)
80% Impervious
.70 . 75 .80 .85
Industrial (2) .80 .85 .90 .95
90% Impervious
NOTES:
(1) Obtain soil group from maps on file with the Department of Sanitation
and Flood Control.
(2) Where actual conditions deviate significantly from the tabulated
imperviousness values of 80% or 90%, the values given for coefficient
C, may be revised by multiplying 80% or 90% by the ratio of actual
imperviousness to the tabulated imperviousness. However, in no case
shall the final coefficient be less than 0.50. For example: Consider
commercial property on D soil group.
Actual imperviousness = 50%
Tabulated imperviousness = 80%
Revised C = |2.X 0.85 = 0.53
AUPPWntY TY
OWEN ENGINEERING GROUP
Civil, Gcolcchnical and Slrudural Engineei iiiv;
June 14, 2000
Mr. Jon Jensen
Jon A Jensen and Associates
451 South Escondido Blvd
Escondido, CA 92025
Subject: Review and Update of Applicable Geology and Geotechnical Reports
re: Parcel No. 210-120-30, Carlsbad, Califomia
Dear Mr. Jensen:
This infomiation is presented in a format which updates all of the referenced reports relative to the
development of your site.
Prior to this report, these reports addressed bluff stability and recommended setbacks relative to the
construction of the proposed dwelling at this site.
Applicable criteria for this development are summarized as followed. Where these values may
differ in the original reports, the design parameters are updated herein and are applicable to your
proposed residence.
As noted in previous reports by this office, the recommended setback from the bluff is 40 feet from
the top of the existing bluff.
Design criteria are as follows:
Item 1. Lateral pressure evaluation based on the angle of intemal friction at 32 degrees and
cohesion of 100 pounds psf
Item 2. Unit soil bearing for continuous foundations located a minimum of 18 inches below
lowest adjacent grade shall not exceed 2500 psf This is a conservative value based
on the Terza^ Unit Bearing Value Formula for this type soil The unit soil bearing
value maybe increased 500 pounds psf for each additional 12 inches of embedment
of the footing relative to the lowest adjacent grade to a maximimi of 4000 psf
Grade measurements, in the event of a basement-type structure, relate to the
measurement of the inside or lowest adjacent grade. This is not a reference to the
finished exterior pad grade.
1525 Grand Ave, San Marcos, Califomia 92069 Telephone (760) 471 - 6000 Fax (760) 471-6096
14661 Myford Road, Suite C, Tustin, California 92806 Telephone (714) 734 - 7993 Fax (714) 734-9732 ^
FILE COPY
Item 3. The soil, as tested, is nonexpansive and no special provisions for slab-on-grade or
similar considerations are required.
Item 4. The foundation system along the westeriy perimeter of the dwelling may include end
bearing caissons placed on fonnation material, located approximately 5 to 8 feet
below grade. Unit soil bearing on formation material shall not exceed 6000 psf
The caisson system is an option. The proposed perimeter grade beam/foundation
will adequately support the proposed structure
Caisson distribution and spacing shall be a part of the structural evaluation and the
dwelling and its foundation system. Note: this is only a recommendation and is not
a requirement for the dwelling "bluff setback" as 40 feet.
Item 5. All slab on grade systems will require a sub-base material to consist of compact
dense free draining soil and/or gravel. Sub-slab materials, within the living areas,
will require the placement of at least 6 mil visqueen and 2 inches of sand as a
leveling course. Concrete slab-on-grades are recommended to be a minimum of 4
inches of thickness and contain reinforcing steel as will be directed by the structural
engineer. A minimum would be a 6 gauge welded wire mat or as directed by the
structural engineer.
The above items are specifically directed to the criteria necessary to design of this building. The
construction procedures shall be observed during embankment construction, or prior to foundation
concrete placement. This inspection will be to insure that the foundation dimensions, locations are
per this report and the associated restrictions imposed by these referenced reports which are
considered a part of this document and per project plans and specifications.
Site drainage must confoim to criteria established to address bluff protection. All drainage shall be
directed away from the dwelling foundations. All drainage to the public right-of-way (roadway)
shall be in conformance with applicable standards (City of Carlsbad, Califomia).
This report is an update to the attached report dated March 16, 1998.
Limitations
Professional judgements presented herein are based partly on our evaluation of the available
technical information that was reviewed, partly on our understanding of the proposed construction,
and partly on our general experience in the civil and geotechnical field.
The recommendations and civil engineering basis of design were based on the assumption that the
soil conditions present at the site do not deviate considerably from those presented in the referenced
reports and investigations performed by others (see references). If variations or undesirable
geotechnical or soil conditions are encountered during construction, the engineering geologist and
civil engineer should be notified immediately and consulted for further recommendations. We do
not guarantee the performance of the project in any respect.
This firm does not practice or consult in the field of safety engineering. We do not direct the
contractor's operations, and cannot be responsible for the safety of other than our own personnel
on the subject site; therefore, the safety of others is the responsibility of the contractor. The
contractor should notify the owner if he considers any of the recommended actions presented herein
to be safe.
Sincerely,
Owen Engineerin
C. J. Randle, P.E.
RCE 22096 CA
References
1. Geotechnical Update, Carisbad Beach Lot, APN 210-120-30, Carisbad Drive,
Carisbad, Califomia; 1966, by Geotechnics, Inc., Project No. 0319-001-00, dated
September 3, 1996.
2. Geotechnical Investigation and Bluff Retreat Study. Parcel No 210-120-39,
Carlsbad, Califomia; 1991, by ICG, Inc., Job No. 04-8529-001-00-00, dated March
28,1991.
3. Geotechnical Investigation and Bluff Refreat Study, Parcel No. 210-120-31,
Carisbad, Califomia; 1989, by ICG, Inc., Job No. 05-8109-001-00-00, dated
November 6, 1989.
4. California's Battered Coast; 1985, Califomia Coastal Commission Meeting,
Professional Papers and Publication, San Diego, Califomia, September, 1985 San
Diego Association of Geologists.
5. Supplemental Geotechnical Investigation, Proposed Coastal Protection Measures for
the 2+1- acre coastal site, Carlsbad, Califomia; 1984, by Converse Consultants,
Project No. 83-2299-02, dated September 20,1984.
6. Geotechnical Investigation, Proposed Coastal Protection Measures for Ecke Site,
Carls bad, Califomia; 1984, by Converse Consultants, Project No. 83-02299-01,
dated February 1,1984.
APPENDIX A
UNIT SOIL BEARING VALUES
TERZAGHI'S BEARING CAPACITY EQUATION
CONDITIONS
Friction Angle ^ = 32-deg
Cohesion c := lOO psf
Maximum Density y:=120 pcf
Footing Width B:=lft z .= 1-ft, 1.5 ft.. B
Footing Depth D =66 in
Effective Overburden Pressure q :=r D q=660'psf
TERZAGHI VARIABLES
(see table 4-1 of Foundation Analysis and Design, Joseph E.
Bowles)
For strip round square
SJ. 1.0 1.3 1.3 S(, -1
S.^ 1.0 0.6 0.8 8.^:=]
N Factors
(For the following values, see Terzaghi bearing-capacity values)
N^;=44.90 N„;=29.5 N.,:=27.8
Bearing Capacity Allowable Bearing Capacity
q^jt(z): = c N^.S^+q-Nq+0.5-r.z.N.^.S^ SF: = 4 q^(z)
SF
z qult(2) ^a(^)
- = I ——=25628 ~—=6407 psf psf