289, Installation of 32 ft by 61 ft, Studies & ReportsRobertQtone & Associates,_.
Engineering Geology • Soil Engineering • Material Testing
8020 Deering Avenue, Canoga Park, California 91304 (213) 346-0565
S:rie 1956
Job No.: 2122-00
uecember:13, 1983 Log No.: 6915 .
Mr. S. M . Kim
20346 Hawthorne Blvd., #109
Torrance, CA 90503
SUBJECT: GEOTECHNICAL EVALUATION.
Swimming Pool and Paddle Tennis Court
Lot 1, Tract 22932
#8 Buggy Whip Drive
Rolling Hills., CA 90274
.INTRODUCTION
SCOPE
;In accordance with your request, a geotechnical study and
evaluation of the subject property has been conducted to
determine geologic safety and feasibility of development
of a swimming pool and tennis court. An areal geologic site
location map has been included with this report. 'The map
is a reproduction of a portion of CDMG Map Sheet 27, "Geology
of the Northeast Part of the Palos Verdes Hills, L.A. County,
1976 by George B..Cleveland.
This investigation was based upon:
1. Geologic field reconnaissance and detailed mapping conducted
December 2, 1983 in conjuction with review of records at
the County of Los Angeles Geology Section and the records
in the offices of Pacific Soils Engineering, Inc. of Harbor
City, CA.
Geology • Soils
• Concrete
• Masonry • Steel
TO:
FROM:
SUBJECT:
•
irked SeuRitt,
ENGINEERING GEOLOGIST
• URBAN GEOLOGY
• SEISMICITY
• GRADING CODE CONSULTANT
3094 ROUNDUP CIRCLE • THOUSAND OAKS, CALIFORNIA 91360 • (805) 492-8127 / 492-8027
April 22, 1982
Project #82111
Mr. Bill Stromberg
2413 Hill Lane
Redondo Beach, CA 90278
C. Michael Scullin
Engineering Geological Evaluation
Lot 1, Tract 22932
#8 Buggy Whip Drive
Rolling Hills, CA 90274
INTRODUCTION•
XMITUI
OCT 141983
CITY OF 6%0 iNG HILL
SCOPE
In accordance•. with your request, an engineering geologic study and
evaluation of the subject property has been conducted to determine
geologic safety and feasibility of development of a horse stable,
riding ring and corrals. An areal geologic site location map has
been included with this report. The map is a reproduction of a
portion of CDMG Map Sheet 27, "Geology of the Northeast Part of
the Palos Verdes Hills, L.A. County, 1976 by George B. Cleveland.
This investigation was based upon:
1. Geologic field reconnaissance and detailed mapping conducted
April 21, 1982 in conjunction with review of records at the
County of Los Angeles Geology Section and the records in the
offices of Pacific Soils Engineering, Inc. of Harbor City, CA.
TV
*age 2
April 22, 1982
Project #82111
2. Review of pertinent reports and geologic' maps of the adjacent
areas prepared by this office and others.
3. Review of the following reports by Pacific Soils Engineering,
Inc.;
(1) Preliminary Soil and Geologic Investigation Report,
WO #5838, July 6, 1965.
(2) Addendum. reports: Sept. 1, 1972; Oct. 23, 1972 and
Dec. 20, 1972, Sept. 22, 1975.
(3) Final. Compaction Report, WO'#200597, Nov. 7, 1975 and
Final Geology Report, Nov.'7, 1975.
4. L.A. County Geology Review Sheet by Mr. Robert...E. Smith,
March 26, 1982.
5. A topography map and as -graded plan at a scale of 1/16" = 1'
and.a 2' contour interval, 10/14/81, by F.J. Salmen & Assoc.
Civil Engineers, Redondo Beach, California.
.ACCOMPANYING ILLUSTRATIONS
Area Geologic Location Map•
(CDMG Special Rpt. 27, 1976)
Site Geologic Map
Page 5
Appendix
•ge 3
April 22, 1982
Project 1182111
PRINCIPALS.
Owner: Mr. Gerry Webber
#2 Buggy Whip Drive
Rolling Hills, CA 90274
Phone: (213) 377-0226
Civil Engineer:
Original Geotechnical
Engineers:.
Engineering
Geologist:
PROPOSED DEVELOPMENT
Number of Lots:
Type of Development:
Adjoining the Site:
Previous Use of Site:
Existing Condition of Site:
Sewage Disposal:
Access to Development:
F.J. Salmen & Associates
1924 S. Pacific Coast Hwy.
Suite "E"
Redondo Beach, CA 90277
Phone: (213) 316-0829
Pacific Soils Engineering,
1402 240th Street
Harbor City, CA
Phone: (213) 775-6771
C. Michael Scullin, EG170
3094 Roundup Circle
Thousand Oaks, CA 91360
Phone: (805) 492-8127
492-8027
nc.
One lot.
Residence, horse stable, riding
ring and 3 to .4 corrals.
N'ly - Residence
S'ly - Residence
E'ly - Buggy Whip Drive
W'ly - Residence and range
Residence and range
Residence, stable, riding ring
and corrals.
Seepage pits
N'ly of Crest Road on Buggy
Whip Drive, E'ly. of Crenshaw
p;
PHYSIOGRAPHIC SETTING
Geomorphic Province:
Landform:
Topographic Relief:
•Page 4
April 22, 1982
Project #82111
Peninsular Ranges
Upper portion of a lateral
canyon
Highest:
Lowest:
1110'±
1050'±
Maximum Relief of Site: 60°±
Average Natural Slope: 2:1 to 10:1
Average Proposed Cut Slope: Retained vertical or 2:1
Maximum Thickness of Fill: 1' to 8'±
Thickness of Topsoil: .. 2' to 3'±
Thickness of Colluvial Soils: 3' to 7'±
Drainage: NW'ly to the ravine and thence
NE'ly
Rainfall:... 12 inches mean annual during
32 year base period: 1932-1964
Climate: Mediterranean • . .
Vegetation: , Mustard, rye grasses, sage,
evergreen and landscaping
Infiltration: Low
Erosion Hazard: Low except where water is
concentrated
Ito
•
0 al
R^PNY OµA Va)sl
CARWG V1V�AN W'
& % i 119
pt 4,t a.
T0*
;i.
4
73j
•
ENGINEERING GEOLOGY
•age 6
April 22, 1982
Project #82111
GENERAL SETTING
The subject site is located on a north and west facing ravine head
of a lateral canyon that drains NW'ly into a north-northeast trending
canyon. The site drainage is northerly to the ravine and thence
northwesterly toward the canyon. The site is within a northeasterly
trending ridgetop of the Palos Verdes Hills, situated within Rolling
Hills, California.
The subject site has been developed as a single family residence.
The site was initially cut and filled as part of a,..grading'permit
that was geotechnically inspected, tested and approved by Pacific
Soils Engineering, Inc., WO #200597, their final approval of
grading and retaining walls Nov. 7, 1975. This report from this
office covers the grading for the horse stable, riding circle and
corrals. •
EARTH MATERIALS
The subject site is underlain by artificial fill (Af), thick adobe
soils (ts), Colluvium (Col), and the Altamira Member (Tma) of the
Monterey Formation of Middle to Upper Miocene Age.
ARTIFICIAL FILL (Af)
The surface of the site contains 1' to 8'± of engineer compacted
:1 St artificial fill throughout most of the building site area. This
?
Sage
pril 22, 1982
Project 1182111
fill was approved by Pacific Soils Engineering, Inc. (see geologic
map:)..` The slope below the stable and the riding ring is composed
of fill containing clay and clayey sand matrix with shale cobbles
and angular fragments. The. fill matrix is dark brown, medium
brown and black, moist and has caving characteristics. The fill
for the riding ring was compacted but not engineered nor tested.
TOPSOIL (ts) and COLLUVIUM (Col)
Topsoil, two tothree feet thick is located throughout the site
and colluvium up to 7' thick underlies the natural slope areas
of the site. The soils are black clayey silt or silty clay. It
is generally moist, firm, soft and contains angular cobble size
fragments of the' bedrock. The engineering parameters of the
topsoil and colluvium are provided by the soil engineer in the
Pacific Soil Engineering reports. It appears to be moist, com-
pressible, plastic and has expansive potential. The slope areas
exposing this soil are located in the corral area.
•
BEDROCK (Tma)
The site is underlain by the Altamira Member of the Monterey
Formation. The bedrock on this site contains siltstone and shale,
gray and rust brown, thin bedded; moist and firm. Interbeds of
siliceous, tuffaceous and diatomaceous shale; gray, rust to buff
brown, and white colored; moist, and very firm to tight with some
black chert. Some of the siliceous interbeds are extremely hard
and blocky.
Some minor fine grained sandstone interbeds are
•age 8
April 22, 1982
Project #82111
occasionally •found. The diatomaceous shale and very hard siliceous
and porcelaneous shale appear to be the predominate bedrock beneath
this site. It is vertically jointed, blocky and breaks along
joints into flat slabs.
GEOLOGIC STRUCTURE
The Cabrillo Fault is located approximately a mile to the northeast
and the Palos Verdes Fault is approximately 4 miles northeast of
the site. The property is involved within a southwesterly dipping
block. The trends are consistently N10-70W and dip southwesterly,
at 12° to 35°. The bedding planes underlying the stable structure
and cut slope dip favorably into the slope. The area geologic -
map by George Cleveland indicates southwesterly dips of 5° to 16°
adjacent to the site. These correlate with the 15° - 20° dips
SW'ly mapped by Pacific Soils Engineering, Inc. during their pre-
liminary investigation and grading. Some dip reversals were noted
beneath the engineered fill below the residence: No shears were
found in the exploration; however, there is some vertical jointing
within the shale interbeds. No landsliding was found within the
site area. A topsoil slump was noted by Pacific Soils adjacent
to the riding ring. The lot area appears favorable due to the
bedding dipping favorably into the slope, the hard tight resistant
bedrock and the engineered fill, stability fill and engineered
retaining walls in the residence area. However,.mudflow potential
within the top soils and colluvium is moderate to high on the
natural slope as is the case throughout the Palos Verdes hills.
•age 9
April 22, 1982
Project 182111
GROUNDWATER .
No free flowing water or seeps were found within the site investi-
gation nor during the Pacific Soils Engineering Inc. investigations.
No water table noted within the data reviewed of the site area.
Thick grasses were noticeable throughout the adjacent lot indi-
cating moisture retention within the adobe topsoils.
CONCLUSIONS
FEASIBILITY OF DEVELOPMENT
The subject site is considered geologically 'safe and feasible for
the proposed residential development, stable, riding ring and
corrals.
FAVORABLE ENGINEERING GEOLOGIC CONDITIONS
1. The underlying bedrock within the site area contains bedding
planes that dip into the natural terrain and are self-supporting
or are stabilized by a stability fill and retaining walls.
2. Groundwater problems are not in evidence nor anticipated.
3. Liquefaction, ground lurching and differential compaction
hazard potential is considered low in the subject building
site areas.
4. Earth materials can be readily excavated with modern earth -
moving equipment.
v;�'+ .: e'er-.... ' •��, t'Y-,�v a.� S ram''-a-�ri .:yy` .�i.s..Luer..w
•:j4.:+.:++ice"'{
416 10
April 22, 1982
Project #82111
UNFAVORABLE ENGINEERING GEOLOGICAL CONDITIONS
1. Thick (adobe) fills, fill, and slopewash soils mantle the site
and appear to have expansive potential and compressible
characteristics.
2. The topsoil and colluvium materials within the rear slope
corral area have a potential for surface mudflow.
GEOLOGIC GUIDELINES AND CONSIDERATIONS
1. Expected ground shaking from possible future earthquakes
is summarized in Table III.and in the following seismic
parameters:
Acceleration
0.2?g
Period . Duration
0;30 seconds 19 seconds
The repeatable high ground acceleration used for design pur-
poses would average 65 percent of the (peak) acceleration.
Low to moderate strong ground motion is anticipated.at the
site during the lifetime of the structures and buildings
should be designed to withstand it according to the building.
code criteria for'seismic design.
2. The roof drainage and yard drainage should be conducted in
improved devices to drain southerly and westerly into the
rubble ravine and thence down the ravine into the riding ring
desilting basin. The concrete culverts and the riding ring
�ge 11
Aril 22, 1982
Project #82111
will act•as a desilting basin that will protect the adjacent
properties.
3. We suggest that the (3) exiting 4" pipes (Section B-B' on the
site plan) be extended toward the desilting basin with a•,
T-joint and perforated stand pipes be constructed in case
basin siltation. '
of
4. The easterly portion of the riding ring should be regraded, to
tilt back toward the toe of landscaped slope with : a swale'
draining southerly into a pipe.. inlet to drain onto the rubble
rip -rap in the basin. Likewise, the access road, from the
stable to the riding circle. should be graded to drain to the
existing drain'swale southerly of the riding circle and thence
down toward the outlet of the concrete culvert.
The outlet of the concrete culvert should be filled with rock
rip -rap similar to the desilting basin inlet. The, culvert
splash pad and velocity reducers do not have a curtain wall
to reduce the undermining due to headward erosion. Conse-
quently, the rip -rap is considered necessary.
•
6. The desilting basin slopes and the rear slope areas should be
planted with fire retardant and water resistant plants or
forage grasses for the horses. The lesslandscape watering
of the rear slope, the longer it will perform without mudflow.
Studies have indicated that the average hillside homeowner in .
the L.A. Basin area uses the equivalent of 75" to 120" of
7.
� ge 12
Aril 22, 1982
Project #82111
rainfall per year per lot in their normal landscape water.
application. With the annual rainfall added to these totals,
the local mediterranean climate ischanged to a rain forest
condition. Such abuse to natural or engineered slopes results
in mudflows. Limited, watering in the summer and no watering
during rainy seasons will generally satisfy water resistant
plants.
The mudflow slump mapped by Pacific 'Soils Engineering, Inc.
has been partially removed and partially covered by fill in
the riding ring area and is not,considered anymore of a
potential hazard than any of the natural slope area.
8. The stable, riding ring and corral areas are considered geo-
logically safe as long as the drainage provisions suggested
above are constructed along with the existing drainage control
already existing and slopes are landscaped or planted. We
. feel that the horse development is safe for its intended use
and should not be a hazard to adjacent properties. The riding
ring area will act as a desilting basin and will provide a
better flood control capability than if left in the natural
state. It should provide much more safety against flood hazard
potential than before.
9. The riding ring-desilting basin slopes are composed ofcom-
pacted fill. However, it was not an engineered compacted fill
and consequently is considered as a non-structural fill. Any
err
Page 13
pril 22, 1982
roject #82111
subsequent conversion to a structural use would require the
removal, keying and recompaction under the supervision of a
soil engineer. The fill was compacted satisfactorily for the
existing purposes intended.
FINAL CONCLUSION
The subject site is considered geologically favorable for the
horse stable, riding ring and corrals providing that the slope
planting and the above guidelines are considered in site design
and construction. This office assumes no responsibility for the
footing and stable construction nor the residential development
done under'. inspection by others.
The geological services that I rendered in this investigation were
performed to the best of my ability, utilizing my best professional
and ethical judgment at the time the work was performed. Conclu-
sions and recommendations presented in this report are professional
opinions, based upon current available data and do not constitute
a warranty.
aWe appreciate being of service to you. If you have any questions,
please do not hesitate to call.
d
a
Respectfully submitted,
CP. /mI e
C . MICHAEL SCULL IN
Engineering Geologist, EG170 cc: (6) Bill Stromberg
(1) File
II •
PACIFIC SOILS I R R INEERiNG, INC.
1402 W. 240TH STREET, HACITY. CALIFORNIA 90710
TELEPHONES: (213) 325-7272 OR 775-6771
Mr. Kirk Gillette •
1506 Crenshaw Blvd.
Torrance, California 90501
•
U ►(H:Vbc....VVI`I I i Vrr we
17921 Sky Park Circle (Suite G)
Irvine. Ca. 92707
• (714) 557-9450
VENTURA COUNTY OFFICE
1429 Thousand Oaks Blvd. (Suite 208)
Thousand Oaks, Ca. 91360
(805) 495-6513
(805) 495-6514
November 7, 1975
Work Order 200597
Subject: Final Geologic Report for.
Lot 1, Tract No. 22932;
#8 Buggywhip Drive
City of Rolling Hills, California
Reference: ' Final Soils Engineering Report on above subject property
dated November 7, 1975 by Pacific Soils Engineering, inc.
(Work Order 200597).
Dear Sir:
This transmittal, prepared in conformance with the grading codes of the City of
Rolling Hills, presents this firm's geologic opinions relative to recent grading on
the subject property. Recommendations of a geologic nature made prior to and
during grading have been incorporated into construction. That is, unsuitable soils
were removed prior to compacted fill placement and an equipment width stabilization
fill was placed along the north margin of the site. •
From the foregoing it is the opinion of this office that the lot is geologically acceptable
for residential construction.
Attached hereto is a grading plan displaying pertinent geologic data. This map was also
utilized for preparation of the referenced soils report which is a companion to this report.
Respectfully submitted,
PACIFIC SOILS ENGINEERING, INC.
By. MI H EL F. MILLS
Engineering Geologist Associate
, Distr.: (6) addressee
MFM:SSN/andi
Reviewed by:
ETT,,Vicresident
•
1
1
Site Address
Location
GEOLOGIC REVIEW SHEET
•
COUNTY OF LOS ANGELES
DEPARTMENT OF COUNTY ENGINEER - FACILITIES
ENVIRONMENTAL DEVELOPMENT DIVISION
ENGINEERING GEOLOGY SECTION
738-2161•
F NF
. SHEET /
BUoWhip. /Ori/N4'.• 1S/7 ar17,'.f"-' ❑
/Je,i /9 * I, i'.//if
Developer/Owner Mr ( L4 / sore'
t% I %rioril ? sspr
Paci i ►C So - G.
Soils Engineer Paed t t Sol 1 - Er'? /r.1 et" rer)
PLAN CHECK .NO. OR DATE OF REPORT(S)
Engineer
Geologist
Review of: • -
Grading Plan No.r��
Building Plan No
Geologic Report Dated
Soils Report Dated
Other
Action: *,
❑ Plan is approved
Remarks:
Prepared by
❑
Plan approved subject to conditions below
DISTRIBUTION:
Plan Check
❑• Dist. Engineer
❑ Developer -Owner
❑ Site Engineer
0 Geologist
❑ Soils Engineer
in Geol. Sect. File
Grading Section
Plan is not approved for reasons below
Oi Submit plans for recheck '
...it ❑ Sec. 309 Code requirements
s �v , he- S C ►� h� al) pee,
met {not met)
it 4he cave« :1 ibe ro pse4
Ir'acljn . 'Thhe eolo psi avJ .so; 1 c h• i>r c-er.
s1o8,JI ,a ke v-ec.ommenc•aCf►on•s on e bads
co r 4he 9ro ASed •c/e ae o men
Reviewed by
Sec.308(b) 3c & e code requirements •
met (not met)
s-,,,ot-4 •
/.•
J•
•
, . ' . % �f �', • '
Date's '.' f
_.�__...._.. _
• •
• • u."4.' '2"," • '.9,1
• "•-•
..... • .... . • tr.
••.!•••••!.. fr,•••, or.•••00.04•• • •!•-•• •
••• • • 1.
(:,;!/3 In :107'0 r..1
••
• • a....*/
Teita: 69-6225
Xavor :-.Puwenburgh
7 7;enr2. noad
271
JUN 1 9 1984
city OF BR0JiNG )11.11$
Dear Mayor Lee'awenburgh:
7n "Sovr,- 1983, I applied or approval of the PPddle
Curt in my backyard .oroperty. Since then, ev=y
o...N-gms`4a1 :Prnb1P.P1 has berm invst4ca4-ed 'or
• .-t 8 ront',.s. This investigation has included resear
by tez .:: of :Professional hydraulic geologists,
enal.-:sgIrs, drainage svFttem experts, including thr,
Co-nty Enainf,,er! All hav, insDected, surveye!',
o.nd ar.,:oro-9d cf the said property. They all have claired
tho 7 wr:tton renortc to the City of P.r)lling 17-771s that
ary 7,.ro*:).7.er is insignificant. Need:ass tc say, the plannir7
.onz•r and the architectural commi-ztee have also bn
3u7olied with the information and have also a7:1-provd.
•
7 -1.0 no ..:nder'.and -.env t'n.e oitv cou,—;1 draas
cs• ::+•7 S . r
anc:„. L have suffered tremendoas loss of t....no and
hrs ser=a:-.a
0:1”s -0,-
71: • • IT': In 4 E7.: S
te.7:71
4
s.
- •
T am :sou.:. job this hasbeen.
T can"- hei o •L.':a _ a.' :. .._:o _rca :nfa:... ly
I cannot c:.ve up my c tru:lcl e beci?,'.:tie I sincre_y fool
.. ... ri'_ o_; e.. C Cam iTTr `7 .'0 :{ t .. on....i- ti lr C'nT:. La Y e . Cl6.0. t _o::,
.- :lave in Ps L..:d ..C.- C:..c: ex f:j . to back
T'erhans he council member Dr.. c.5jects 4-o my
project due to fear of drairaae .problems. If so, I.belic.ve
that the worries can be ameliorated by realizing that
his drainage Water source is from Johns Canyon .?O%.C' , `
wl_c^ is over. fifty feet from my prover_ ty,._,retinated.
The South Bay, rn _neering Company will orov.. e for the
next meeting, sc_tec :zled June 23, 1984, a t000craphical
map of the elevation, showing, the exact circumstances of
the area in .total, of 48 Bossy ,'hip Dr'_ve, Rolling
California, 90274. In addition, another map displaying the
proposed drainage systems for the Paddle Tennis Court will
shown. Totally avoiding Dr. Beinsheimer's property,
no drainage problem can result.
Pease try to sympathize with the situation and help me
arrive at a final conclusion, without further delay. I
have waited patiently and anxiousl y for a very long time.
Isn't, this entire matter, suite a minor matter, receiving
much too much deliberation b_y the council? I await hopefully
for a goo_. outcome.
yours truly
...„41000
Iiiipp...--
. _ Juggy ',+Thip .Drive
Rolling Hills, California 90274
j2 acre lot;
SlK/c?C
cc: William D. < iba no:c, ^sc.
Robert Stone :i Associates of Geologists, Mr. r'ichael Soul
Los Angeles ^__lttn _v of .'ngi neers, Mr. Xennet': Harvey
South Bay Engineers, Mr. Dour. McHatt_e
C.;;-v Manager, Ron 'f'.ol edy:c
C. KtLdweE Scux
ENGINEERING GEOLOGIST
• URBAN GEOLOGY
• SEISMICITY
• GRADING CODE CONSULTANT
TO:
FROM:
SUBJECT:
SCOPE
•
C. KtickneQ SCUQLIL
ENGINEERING GEOLOGIST
• URBAN GEOLOGY
• SEISMICITY
• GRADING CODE CONSULTANT
3094 ROUNDUP CIRCLE • THOUSAND OAKS, CALIFORNIA 91360 • (805) 492-8127 / 492-8027
April 22, 1982
Project #82111
Mr. Bill Stromberg
2413 Hill Lane
Redondo Beach, CA 90278
C. Michael Scullin
Engineering Geological Evaluation
Lot 1, Tract 22932
#8 Buggy Whip Drive
Rolling Hills, CA 90274
INTRODUCTION
5C/F3710
OCT 14,983
CITY OF a‘u4.L;NGHI-LLS
By. .._._. ' (
In accordance with your request, an engineering geologic study and
evaluation of the subject property has been conducted to determine
geologic safety and feasibility of development of a horse stable,
riding ring and corrals. An areal geologic site location map has
been included with this report. The map is a reproduction of a
portion of CDMG Map Sheet 27, "Geology of the Northeast Part of
the Palos Verdes Hills, L.A. County, 1976 by George B. Cleveland.
This investigation was based upon:
1. Geologic field reconnaissance and detailed mapping conducted
April 21, 1982 in -conjunction with review of records at the
County of Los Angeles Geology Section and the records in the
offices of Pacific Soils Engineering, Inc. of Harbor City, CA.
Page 2
April 22, 1982
Project #82111
Review of pertinent reports and geologic• maps of the adjacent
areas prepared by this office and others.
3. Review of the following reports by Pacific Soils Engineering,
Inc.;
(1) Preliminary Soil and Geologic Investigation Report,
(2)
(3)
WO #5838, July 6, 1965.
Addendum. reports: Sept. 1, 1972; Oct. 23, 1972 and
Dec. 20, 1972, Sept. 22, 1975.
Final Compaction Report, WO #200597, Nov. 7, 1975 and
Final Geology Report, Nov.'7, 1975.
4. L.A. County Geology Review Sheet by Mr. Robert E. Smith,
March 26, 1982.
5. A topography map and as -graded plan at a scale of 1/16" = 1'
and,a 2' contour interval, 10/14/81, by F.J. Salmen & Assoc..
Civil Engineers, Redondo Beach, California.
ACCOMPANYING ILLUSTRATIONS
Area Geologic Location Map
(CDMG Special.Rpt. 27, 1976)
Site Geologic Map
Page 5
Appendix
Civil, Engineer:
Original Geotechnical
Engineers:
Engineering
Geologist:
PROPOSED DEVELOPMENT
Number of Lots:
Type of Development:
Adjoining the .Site:
Previous Use of Site:
Page 3
April 22, 1982
Project #82111
Mr. Gerry Webber
#2 Buggy Whip Drive
Rolling Hills, CA 90274
Phone: (213) 377-0226
F.J. Salmen & Associates
1924 S. Pacific Coast Hwy..
Suite "E"
Redondo Beach, CA 90277
Phone: (213).316-0829
Pacific Soils Engineering, Inc.
1402 240th Street
Harbor City, CA
Phone: (213) 775-6771
C. Michael Scullin, EG170
3094 Roundup Circle
Thousand Oaks, CA 91360
Phone: (805) 492-8127
492-8027,
One lot.
Residence, horse stable, riding
ring and 3 to 4 corrals.
N'ly - Residence
S'ly - Residence
E'ly - Buggy Whip Drive
W'ly - Residence and range
Residence and range
Existing Condition of Site: Residence, stable, riding ring
and corrals.
Sewage Disposal: Seepage pits
Access to Development: N'ly of Crest Road on Buggy
Whip Drive, E'ly of Crenshaw
PHYSIOGRAPHIC SETTING
Geomorphic Province:
Landform:
Topographic Relief:
Maximum Relief, of Site:
Average Natural Slope:
Average Proposed Cut Slope:
Maximum,Thickness of Fill:,
Thickness of Topsoil:
Thickness of Colluvial Soils:
•
Drainage:
Rainfall:,,
Climate:
Vegetation:
Infiltration:
Erosion Hazard:
Page 4
April 22, 1982
Project 182111
Peninsular Ranges
Upper portion of a lateral
canyon
Highest: 1110'±
Lowest: 1050'±
60'±
2:1 to .10:1
Retained vertical or 2:1
1' to 8'±
2' to 3'± .
3' to 7' ±
NW'ly to the ravine and thence
NE'ly
12 inches mean annual during
32 year base period: 1932-1964.
Mediterranean
Mustard, rye grasses, sage,
evergreen and landscaping
Low
Low except where water is
concentrated
•
I�11
°22.30"
CARTOGRAPHY DRAFTED BY
VIVIAN W. MUSTON
CNA& tNIAte Sit. 21
(71a.+a. I l g7lo. y
ono'
111
C Oql a1��'•
tlrl, •
��
•
C�
Page 6
April 22, 1982
Project #82111
ENGINEERING GEOLOGY
GENERAL SETTING
The subject site is located on a north and west facing ravine head
of a lateral canyon that drains NW'ly into a north-northeast trending,,
canyon. The site drainage is northerly to the ravine and thence'
northwesterly. toward the canyon. The site is within a northeasterly
trending ridgetop.of the Palos Verdes Hills, situated within Rolling
Hills, California.
The subject site has been developed as a single family residence.
The site was initially cut and filled as part of a grading permit
that was geotechnically inspected, tested and approved by Pacific.
Soils Engineering, Inc., WO #200597., their final approval of
grading and retaining walls Nov. 7, 1975. This report from this
office covers the grading for the horse stable, riding circle and
corrals.
EARTH MATERIALS '
The subject site is underlain by artificial fill (Af), thick adobe,
soils (ts), Colluvium (Col), and the Altamira Member (Tma) of the
Monterey Formation of Middle to, Upper Miocene Age.
ARTIFICIAL FILL (Af) '
The surface of thesite contains 1' to 8'± of engineer compacted
artificial fill throughout most of the building site area. This
Page 7
April 22, 1982
Project #82111
fill was approved by Pacific Soils Engineering, Inc. (see geologic
map'.)...The slope below the stable and the riding ring is composed
of fill containing clay and clayey sand matrix with shale cobbles
and angular fragments. The fill matrix is dark brown, medium
brown and black, moist and has caving characteristics. The fill
for the riding ring was compacted but not engineered nor tested.
TOPSOIL (ts) and COLLUVIUM (Col)
Topsoil, two to three feet thick is located throughout the site
and colluvium up to 7' thick underlies the natural slope areas
of the site. The soils are black clayey silt or silty clay. It
is generally moist, firm, soft and contains angular cobble size
fragments of the bedrock. The engineering parameters of the
topsoil and colluvium are provided by the soil engineer in the
Pacific Soil Engineering reports. It appears to be moist, com-
pressible., plastic and has expansive potential. The slope areas
exposing this soil are located in the corral area.
BEDROCK (Tma)
The site.is underlain by the Altamira Member of the Monterey
Formation. The bedrock on this site contains siltstone and shale,
gray and rust brown, thin bedded, moist and firm. Interbeds of
siliceous, tuffaceous.and diatomaceous shale; gray, rust to buff
brown, and white colored; moist, and very firm to tight with some
black chert.
and blocky.
Some of the siliceous interbeds are extremely hard
Some minor fine grained sandstone interbeds are
Page 8
April 22, 1982...
Project #82111
occasionally.found. The diatomaceous shale and very hard siliceous
and porcelaneous shaleappear_ to be the predominate bedrock beneath
this site.It is vertically jointed, blocky andbreaks along.
joints into fiat slabs.
GEOLOGIC STRUCTURE
The Cabrillo Fault is located approximately a mile to the northeas
and the Palos Verdes Fault is approximately 4 miles northeast of
the site.. The property, is involved within a southwesterly dipping
block. The trends are consistently N10-70W and dip southwester,ly,.
t.12° to 35°. The bedding planes underlying the stable structure..
and cut slope dip favorably into the slope. The area geologic:'.
map by George Cleveland indicates southwesterly dips of 5° to 16°.
adjacent to the site. These correlate with the 15° - 20° dips
SW'ly mapped by. Pacific Soils Engineering, Inc. dur.ing their pre-
liminary investigation and grading.' Some dip reversals were noted
beneath .the engineered fill below the residence. No shears were
found in the exploration; however, there is some vertical jointing
within the shale interbeds. No landsliding was found within the
site area. A:topsoil slump was noted by Pacific Soils adjacent
to the riding ring. The lot area appears favorable due to the
bedding dipping favorably into the slope, the hard tight resistant
bedrock and the engineered fill, stability fill and engineered
retaining walls in the residence area. 'However, mudflow potential
within the top soils and colluvium is moderate to high on the
natural slope as is the case throughout the Palos Verdes hills._
Page 9
April 22, 1982
Project #82111
GROUNDWATER
free flowing water, or seeps were .found within the site investi-,
gation,nor during. the Pacific Soils Engineering Inc. investigations.,
No water table noted within the data reviewed, of the site area..
Thick grasses were noticeable throughout the
adjacent lot indi-
cating moisture retention within the' adobe topsoils.
CONCLUSIONS
FEASIBILITY OF DEVELOPMENT
The subject site is consideredgeologically 'safe and feasible for
proposed residential development, stable, riding ring
FAVORABLE ENGINEERING GEOLOGIC CONDITIONS
The underlying bedrock within the site area contains bedding
planes that dip into the natural terrain and are self-supporting
or are stabilized by a stability fill and retaining walls.
Groundwater problems are not in evidence nor anticipated.
Liquefaction, ground lurching and differential compaction
hazard potential is considered low in the subject building
site areas.
Earth materials can be readily excavated with modern earth-
moving equipment.
Page 10
April 22, 1982
Project 1182111
UNFAVORABLE ENGINEERING GEOLOGICAL CONDITIONS
.Thick (adobe) fills,, fill, and slopewash soils mantle the
and appear to have expansive potential and compressible
characteristics.
The topsoil and colluvium materials within the rear slope
corral area have a potential for surface mudflow:
GEOLOGIC GUIDELINES AND CONSIDERATIONS
1. Expected ground shaking from possible future earthquakes
is summarized in Table III .and in the following seismic
parameters:
Acceleration Period Duration
0.27g 0;30 seconds 19 seconds
The repeatable high ground acceleration used for design pur-
poses would average 65 percent of the (peak) acceleration.
Low to moderate strong ground motion is anticipated,at the
site during the lifetime of the structures and buildings
should be designed to withstand it according to the building,
code criteria for seismic design.
,The roof drainage and yard drainage should be conducted in
improved devices to drain southerly and westerly into the
rubble ravine and thence down the ravine into the riding ring
desilting basin. The concrete culverts and the riding ring
Page 11
April 22, 1982
Project #82111
will act•as a desilting basin that will protect the adjacen
properties.
:!';We suggest that the (3) exiting 4" pipes (Section B-B'
site plan) be extended toward the desilting basin with a'
T-joint and perforated stand pipes be constructed in,case .:.of
basin siltation.
The easterly portion of the riding ring should be regraded to
tilt back toward the toe of landscaped slope with a swale',
draining southerly into a pipe.. inlet to drain onto the rubble
rip -rap in the basin. Likewise, the access road from the
stable to the riding circle should be graded to drain to the
existing drain swale southerly of the riding circle and thence
down toward the outlet of the concrete culvert.
The outlet of the concrete culvert should be filled with rock"'
rip -rap similar to the desilting basin inlet. The culvert
splash pad and velocity reducers do not have a curtain wall
to reduce the undermining due to headward erosion. Conse
.quently, the rip -rap is considered necessary..
11. 6. The desilting basin slopes and the rear slope areas should be
planted with fire retardant and water resistant plants or,
forage grassesfor the horses. The less landscape watering,
of the rear slope, the longer it will perform 'without mudflow..
Studies have indicated that the average hillside homeowner. in.?..�`
'the L.A. Basin area uses the equivalent of 75" to 120" of
Page 12
April 22, 1982
Project #82111
rainfall per year per lot in their normal landscape water
application. With the annual rainfall added to these totals,.:
the local mediterranean climate is changed to a rain forest.,
condition. Such abuse to natural or engineered slopes results
in mudflows. Limited watering in the summer and no watering
during rainy seasons will generally satisfy, water resistant
plants.
The mudflow slump mapped by Pacific Soils Engineering, Inc.
has been.partially removed and partially covered by fill in.
the riding. ring area and is not,considered anymore of
potential hazard than any of the natural slope area.
The stable, riding ring and corral areas are considered geo-
logically safe as long as the drainage provisions suggested.
above are constructed along with the existing drainage control
already existing 'and slopes are landscaped or planted. We
feel that the horse development is safe for its intended use
and should not be a hazard to adjacent properties. The riding
ring area will act as a desilting basin and will provide a
better flood control capability than if left in the natural,
state. It should provide much more safety against flood hazard
potential than before.
The riding ring-desilting basin slopes are composed of com-
pacted fill. However, it . was not an engineered compacted fill
and consequently is considered as a non-structural fill. Any,
Page 13
April 22, 1982
Project 482111
subsequent conversion to'a structural use would require the
removal, keying and recompaction under the supervision of a
soil engineer. The fill was compacted satisfactorily for the
existing purposes intended.
FINAL CONCLUSION
The subject site is considered geologically favorable for thee.
horse stable, riding ring and corrals providing that the slope
planting and the above guidelines are considered in site design
and construction. This office assumes no responsibility for the
footing and stable construction nor the residential development
done under inspection by others.
',The. geological services that I rendered in this investigation were,
performed to the best of my ability, utilizing my best professional
and ethical judgment at the time the work was performed. Conclu-
sions and recommendations presented in this report are professional
opinions, based upon current available data and do not constitute,.
We.appreciate being of service to. you. If you have any questions,
please do not hesitate to call.
Respectfully submitted,
C.,MICHAEL SCULLIN
Engineering Geologist, EG170
cc: (6) Bill Stromberg
(1) File
PACIFIC SOILS ENGINEERING, INC.
1402 W. 240TH STREET, HARBOR CITY, CALIFORNIA 90710
TELEPHONES: (213) 325-7272 OR 775.6771
Mr. Kirk Gillette
1506 Crenshaw Blvd.
Torrance, California 90501'
Subject: Final Geologic Report for.
Lot 1, Tract No. 22932;
#8 Bu.ggywhip Drive
City of Rolling Hills, California
Reference: ' ' Final Soils Engineering Report on above subject property
dated November 7, 1975 by Pacific Soils Engineering, Inc.
(Work Order 200597). '
ORANGE COUNTY OFFICE
17921 Sky Park Circle (Suite G)
Irvine, Ca. 92707
(714) 557.9450
VENTURA COUNTY OFFICE
1429 Thousand Oaks Blvd. (Suite 208) ,
Thousand Oaks, Ca. 91360
(805) 495.6513
(805) 495.6514
November 7, 1975
Work Order 200597
Dear Sir:.
This transmittal, prepared in conformance with the grading codes of the City of
Rolling Hills, presents this firm's geologic opinions relative to recent grading on
the subject property. Recommendations of a geologic nature made prior to and
during grading have been incorporated into construction. That is, unsuitable soils
were removed prior to compacted fill placement and an equipment width stabilization
fill was placed along the north margin of the site.
From the foregoing it is the opinion of this office that the lot is geologically acceptable
for residential construction. '
Attached hereto is a grading plan displaying pertinent geologic data. This map was also
utilized for preparation of 'the referenced soils report which is a companion to this report.
Respectfully submitted, '
PACIFIC SOILS ENGINEERING, INC.
By:
MIHAEL F. MILLS
Engineering Geologist Associate
Distr.: (6) addressee
MFM:SSN/andi
Reviewed by:
ETT, Vicq/President
641
GEOLOGIC REVIEW SHEET
COUNTY OF LOS ANGELES
DEPARTMENT OF COUNTY ENGINEER - FACILITIES SHEET / OF
ENVIRONMENTAL DEVELOPMENT DIVISION
ENGINEERING GEOLOGY SECTION
738.2161• . . DISTRIBUTION: „
SiteN Address BV4 0 W !7 // t , A ' /'iye.. L S / Tr- �j' a ' Plan Check
o M// Location /rt J / / J/j ❑
172. Dist. Engineer
Developer/Owner Mt (1 ; Piing / ,- e v ❑ Developer -Owner .;
Engineer . tr ./5,Q/ r on /I Sot t ❑ Site Engineer
Geologist Pa G i lie t 50 i I T ti q, w-I v,,srcN-1 0 Geologist
Soils Engineer PQ C d T l e Soli- - E nil (.1 . f .-.,-,,,,pi).
g❑ Soils Engineer
PLAN CHECK NO. OR DATE OF REPORT(S) ' ' m Geol. Sect. File
m Grading Section:
NF�
Grading Plan No._Irs-c% A
Building Plan No.
❑ Geologic Report Dated
❑ Soils Report Dated
❑ Other
Action: r
❑ Plan is approved ® Plan is not approved for reasons below
Plan approved subject to conditions below
it4he avea — , e roposeEl
zi
racl,l;r, "ThInd .7o) 1 eir►�.er,
Shou.lo1 make ''reoommer daPI;d.,s Cr) 411e ba.sl
OSel 410 went.
4 he, r
Prepared by
Reviewed by
t.
El Submit plans for recheck '
Sec. 309 Code requirements
met (not met)
Sec.'308(b) 3c & e code requirements;.',
met (not met)
%)Lam 24, (f ra,
Date //e