HomeMy WebLinkAboutm30289-11r
DONALD R. WARREI`
ENGINEERS
930 W. SUNSET BOULEVARD
LOS ANGELES, CALIFORNIA 90012
626-0101
7ol,
F I N A L
ate 10/13/66 1
REPORT ON COMPACTION
S het l _ of. --'
Tract No. 30289 Lots Complete Tract and offsite Area
Location Diamond Bar Blvd. and Shadow Canyon Dr . , Diamond Bar, Calif.
Client Transamerica Development Company
Client's Address 2900 Brea Canyon Road; Diamond Bar, California
Engineer Dutch Holzhauer Engr. , Inc . Contractor Strecker
General: Type of Soil. Native Sand, Silt, Clay, Siltstone and Sandstone Mixtures
Imported Alone
Before placing fill the existing surface was stripped of vegetation, scarified, watered as required, and com.
pacted. Inspection of the stripped surface indicated the area to be original ground. The determination of voids
or geologic weaknesses is not included in the scope of this report. Where natural slopes existed, benches were
cut into the slopes as the fills progressed, to provide a firm bond between natural ground and the compacted fill.
The fill -vas placed in layers 6 to 8 inches in thickness, watered and compacted by
sheepsfoot rollers and controlled routing of earth -moving equipment.
Inspections and field density tests were made by the Donald R. Warren Co. during the progress of the job. The
results and estimated locations of tests and limits of compacted areas are attached as part of this report.
Special Conditions:
Reference is made to the Engineering Reports (F 65-174) related to the
development of the subject tract prepared by the Donald R. Warren Co.
and the Geologic Reports prepared by James E. Slosson and Associates.
Trees, roots, trash and debris were removed from the subject site.
All excavations made during site clearance were brought to grade
with compacted fill. No other obstructions, surface or subsurface,
were encountered.
SPECIAL CONDITIONS, Continued on Page 2 -
Recominendations: On the basis of inspection during grading, attached results of field density tests at selected
points, and results of stability tests on the soil types used, it is our opinion that the compacted areas are adequate for
design loads of 1500 pounds per square foot for residential footings, square or continuous, placed 12
inches below finished grade.
Note: A warranty is not implied, nor should one be construed.
RC-JF/DRC/gs
Respectfully submitted
DONALD R. WARREN CO.
Distribution:
5 Transamerica Development Company By AKZI—
2 - L.A. County Bldg. and Safety Div. —
1 -- Dutch Holzhauer Engr. Inc./w.certificate
1 - James E. Slosson and Assoc. Review by
DONALD R. WARREN
ENGINEMPts
Job No. F65-174
Client
Tract No.
rest
No.
Transamerica Development C
30289
an
RESULTS OF FIELD DENSITY TESTS
Date 10/13/66
Sheet 2 of
Field Moisture Field Density Maximum Density Percent
Percent Lhs./Cu. Ft. Lbs.ICu. Ft. maximum
SPECIAL CONDITIONS, Continued -
Poorly consolidated soils and alluvium were removed to firm
natural soil or bedrock prior to placing compacted fill.
Subdrains were constructed at the contact between the cleaned
canyon bottoms and the compacted fill. Elevations and types of
subdrains were determined in the field during inspection by
representatives of Dr. James E. Slosson, the tract geologist,
and Donald R. Warren Co.
Compacted fall buttresses were constructed to the estimated limits
shown on the attached figure against portions of the cut slopes
descending to the streets from Lots 2, 6, 7, 9--18, 52-56 inclusive,
and the rear portion of Lots 66--68 inclusive. Subdrains -were
incorporated into the compacted fill buttress at the contact with
the natural ground. Elevations and types of subdrains were
determined in the field.
To restrict the infiltration of landscape water into the underlying
bedded material, the level cut area of Lots 19-21, 24-»28 inclusive,
69 and 70 were undercut 30+ inches and the material was replaced
as a compacted fill blanket.
Compacted fill was placed on Lots 1--21, 24--36, 40, 41, 47-64 and
66--70 inclusive to facilitate the grading and placement of the
adjacent streets. The major portions of the lots were left at
natural grade. Compacted fill was placed in canyons, adjacent
to the streets and offsite to the tract, to bring the areas up to
an elevation to provide adequate lot drainage to the streets.
It is suggested that the following general conditions be observed
with reference to proximity of footings to the compacted edge of fill
slopes:
Vertical Height
of 1--1/2:1 Slope
Minimum Distance of Footing
from a 1 on 1--1/2 plane
Projected Upward from Toe of Slope
0 to 5 feet 3 feet
5 to 20 feet 5 feet
Over 20 feet 10 feet
Field Investigation: field density tests were taken at locations shown, according to A.A.S.H.O. Standard Test
Method T 147-49.#Bag samples of representative fill materials were obtained for laboratory tests.
and the driven --ring undisturbed sample method.
Laboratory Tests: Moisture determinations were made on sealed samples from each field test. Compaction
tests were performed on representative soils according to A.S.T.M. Standard Test 1Vfethod D 698-57T, modified
to use 25 blows of a 10-pound hammer falling 18 incltes on each of 3 layers in a 4-inch diameter cylindrical mold
of 1 /30 cubic foot volume.
DONALD R. WARREN
ENCINIER!
Job No. F 65-174
Client Transamerica Development Company
Tract No. 30289
RESULTS OF FIELD DENSITY TESTS
Test field Moisture
No. Percent
SPECIAL CONDITIONS Continued -
Vertical
Height of 2:1 Slope
0 to 20 feet
Over 20 feet
Date J-0--13-66
Sheet 3 of
Field Density Maximum Dcnsity
Lbs./Cu. Ft. Us./Cu. Ft.
Percent
Maximum
Minimum Distance of Footing
from a 1 on 2 plane
Projected Upward from Toe of Slope
3 feet
5 feet
If plans call for encroachment, It is our opinion that the footings
should be deepened to conform to the above.
Adequate measures to provide proper slope protection and drainage
should be constructed in accordance with the grading ordinance,
as the above recommendations assume full lateral support of the
compacted fill. The surfaces of the compacted fill slopes were
trimmed back or gridrolled and tests indicate a firm compacted
surface was obtained.
Basic Soil Type (without Rock)
Laboratory)
Optimum Moisture
in Percent
14.1
13.5
13.2
14.7
20.0
19.8
16.7
9.9
11.2
13.6
13.8
13.6
11.3
17.5
18.0
20.2
13.6
Maximum Density
P. c, f.
110
112
113
107
97
99
103
120
116
108
lob
109
117
102
101
97
109
Field Investigation: Field density tests were taken at locations shown, according to A.A.S.H.O. Standard Test
Method T 147-49. Bag samples of representative fill materials were obtained for laboratory tests.
and the driven —ring undisturbed sample method.
Laboratory Tests: Moisture determinations were made on sealed samples from each field test. Compaction
tests were performed on representative soils according to A.S.T.M. Standard Test Method D 698-57T, modified
to use 25 blows of a 10-pound hammer falling 18 inches on each of 3 layers in a 4-inch diameter cylindrical mold
of 1/30 cubic foot volume.
DONALD R. WARREN
ENOIN6CRi
Client Transamerica Development Company
Tract No. 30289
Test
No.
RESULTS OF FIELD DENSITY TESTS
Field Moisture
Percent
Field Density
Lbs./Cu. Ft.
Job No. F 65-174
Dttte 10-13-66
Sheet 4 of
Maximum Density
LLs./Cu. Ft.
SPECIAL CONDITIONS, Continued --
Continued - Basic Soil Type (Without Rock)
Laboratory)
Optimum Moisture Maximum Density
in Percent P. C. f.
10.0 116
15.4 107
13.0 110
14.7 107
14.9 105
13.2 ill
Percent
Maximum
It should be noted that this report is concerned only with the
compaction of fills during the rough grading of the tract; future
cutting, filling or terracing to create level pads should be done
under the inspection of a qualified soils entineer. Reference
to our Job No. F 65-174 would help materially in re-establishing
the complete file.
The results of swell tests made on samples of the soil types which
might affect foundation design, remolded to 90 percent of maximum
density at a moisture content at or below the shrinkage limit or
80 percent of optimum moisture whichever is lower and immersed in
water for 24 hours, are as follows:
Sample
No.
1
14
15
16
17
18
Soil Classification
Sandy Clay
Silty Clay
Clayey Siltstone
Siltstone
Sandy Clay
Sandy Silt Clay
Percent Swell Under
60 p.s.f. Loading
2.8
8.0
4.8
6.1
7.3
6.1
SPECIAL CONDITIONS, Continued on Page 5 -
Percent Swell Under
650 p. s .f . Loading
0.4
2.1
0.9
1.6
0.8
0.5
Field Investigation: Field density tests were taken at locations shown, according to A.A.S.H.O. Standard Test
Alethod T 147-44* Bab samples of representative fill inaterials were obtained for laboratory tests.
and the driven —ring undisturbed sample method.
Laboratory Tests: Moisture determinations were made on sealed samples from each field test. Compaction
tests were performed on representative soils according to A.S.T.M. Standard Test Method D 69UO-57T, modified
to use 25 blows of a 10-pound hammer falling 18 inches on each of 3 layers in a 4-inch diameter cylindrical mold
of 1/ 30 cubic foot volume.
DONALD R. WARRCN
ENOINE[Rs
Client Transamerica Development Company
Tract No. 3028D
Test
No.
RESULTS OF FIELD DENSITY TESTS
Field Moisture
Percent
SPECIAL CONDITIONS, Continued -
Field Density-
Lhs./Cu. Ft.
Job No. F 65--174
Date 10-13--66
Sheet 5 of
Maxunum Density Percent
Us./Cu. Ft. Maximum
Based upon the results of the swell tests, Sample No. 1 is
considered to be slightly expansive under slab loads and non --
expansive under footing loads; Sample Nos. 14 and 16 are considered
to be moderately expansive under slab and footing loads; and
Sample Nos. 15, 17 and 18 are considered to be moderately expansive
under slab loads and slightly expansive under footing loads.
The following is the recommended procedure concerning the treatment
of subgrade soils and residential footings where slightly
expansive soils exist:
1. All footings for single story residential dwellings should
bear at least 12 inches below finished grade, and continuous
footings should be used under all bearing partitions. All
footings should be reinforced with No. 4 bars running -
continuously, one in the top of the stem wall and one in the
bottom of the footing.
2. Positive drainage should be provided away from the structure.
3. Gutters and downspouts will not be required unless adverse
drainage conditions exist contrary to Item 2 above.
Where slab construction is planned, the following treatment is
recommended in addition to the foregoing:
4. House and garage slabs should be reinforced with 6 x 6 -- 10/10
welded wire fabric or equivalent reinforcing steel.
5. If conventional financing is used, a moisture barrier should
be provided beneath the slab within the living area, either in
the form of a barrier membrane such as Visqueen or a capillary
break base course having a minimum thickness of 4 inches.
If the base course is selected, the material should consist
of crushed rock of maximum one -inch size. If FHA or VA insured
financing is used, a moisture barrier will be required in
accordance with their standards.
The following is the recommended procedure concerning the treatment
of subgrade soils and residential footings where moderately expansive
soils exist:
Field Investigation: Field density tests were taken at locations shown, according to A.A.S.H.O. Standard Test
Method T 147.49. Bag samples of representative fill materials were obtained for laboratory tests.
and the driven —ring undisturbed sample method.
Laboratory Tests: Moisture determinations were made on sealed samples from each field test. Compaction
tests were performed on representative soils according to A.S.T.M. Standard Test Method D 698-57T, modified
to use 25 blows of a 10-pound Hammer falling 18 inches on each of 3 layers in a 4-inch diameter cylindrical mold
of 1 /30 cubic foot volume.
DONALD R. WARRiN
ENGINEER•
Jab No. F 65 —17 4
Client Transamerica Development Company
Tract No. 30289
Test
No.
RESULTS OF FIELD DENSM TESTS
Field Moisture
Percent
SPECIAL CONDITIONS, Continued -
Date
Sbeet 6 of
Field Density Maximum Density Percent
Lbs./Cu. Ft. Lb-s./Cu. Ft. Maximum
1. All footings for single story residential dwellings should bear
at least 12 inches below finished grade, and continuous footings
should be used under all bearing partitions. All footings should
be reinforced with No. 4 bars running continuously, one in the
top of the stem wall and one in the bottom of the footing.
2. Positive drainage should be provided away from the structure.
3. Gutters and downspouts will not be required unless adverse
drainage conditions exist contrary to Item 2 above.
Where slab construction is planned, the following treatment is
recommended In addition to theforegoing:
4. House slabs should be reinforced with 6 x 6 10/10 welded wire
fabric or equivalent reinforcing steel.'
5. Garage slabs should be reinforced with 6 x 6 -- 10/10 welded wire
fabric or equivalent reinforcing.steel and should be cast
independently of the stem wall. A positive separation of
expansion joint material should be provided between the
slab and the stem wall.
60 If conventional financing is used, a moisture barrier should be
provided beneath the slab within the living area, either in the
form of a barrier membrane such as Visqueen or a capillary break
base course having a minimum thickness of 4 inches. If the base
course is selected, the material should consist of crushed rock
of maximum one -inch size. If FHA or VA insured financing is used,
a moisture barrier will be required in accordance with their
standards.
7. The soils beneath all slabs should be wetted sufficiently to obtain
a moisture content well in excess of optimum to a depth of 18 to
20 inches below subgrade.
8. The depth of penetration of the water should be checked by a
qualified soils engineer prior to placing concrete, since the
depth of penetration is critical. The addition of detergent to
reduce surface tension would increase the rate of penetration.
Field Investigation: field density tests were taken at locations shown, according to A.A.S.H.O. Standard Test
Method T 147-49.*Bag samples of re resentative fill materials were obtained for laboratory tests.
and the riven —ring undisturbed sample method.
Laboratory Tests: Moisture determinations were made on sealed samples from each field test. Compaction
tests were performed on representative soils according to A.S.T.M. Standard Test Method 1) 698-57T, modified
to use 25 blows of a 10-pound hammer falling 18 inches on each of 3 layers in a 4-inch diameter cylindrical mold
r 1 inn .. 1.......,.1........
DONALO R. WARREN
ENGiKrews
Job No. F 65 --17 4
Client Transamerica Development Company Date 10-13-66
Tract No. 30239 Sheet 7 of
Test
No.
RESULTS OF FIELD DENSITY TESTS
Field Moisture
Percent
SPECIAL CONDITIONS, Continued -
Field Density
Lbs./Cu. Ft.
Maximum Density Percent
Us./Cu. Ft. Maximum
U
No special foundation requirements are necessary where non -expansive
soils exist.
Since the lots were left at natural grade and no specific building
areas were constructed at this time, it is recommended that upon
completion of grading of the individual pad areas, a qualified
soils engineer check each lot for the degree of expansiveness of the
soils.
TESTS,
Foilowing Pages
Field Investigation: Field density tests were taken at locations shown, according to A.A.S.H.O. Standard Test
Method T 147.49 "LBag samples of representative fill materials were obtained for laboratory tests.
and the driven —ring, undisturbed sample method.
Laboratory Tests: Moisture determinations were made on scaled samples from each field test. Compaction
tests were performed on representative soils according to A.S.T.M. Standard Test 1Jethod D 69;-57T, modified
to use 25 blows of a 10-pound hammer falling IS inches on each of 3 layers in a 4-inch diameter cylindrical mold
t 1 /Rfl...,h;n fnnt vnlnma.
Ctient Trans Amsrica o r-tober,
Tr -,ct; No 30?_r39 ` f ' t 20 l
JLT ; Q F F: H-LD D-'•:':- ITY T ",'I':
Test Date of
No. Test
F' e.a I,c' st,._ hlEx. Dencity Percent
erc rat ',,bs. C' Ft Lbs C:,i Ft M,,X-! mum
479 12/24/65 18.2 100 107
480 12/24/65 14.,5 107 112
481 12/24/65 16.1 107 110
482 12/27/65 15.7 102 3.12
483 1.2/27/65 15.2 110 112
484 12/27/65 12.6 112 116
485 12/07/65 11.5 111 116
486 12/27/65 12.0 107 116
487 12/27/65 14.4 110 116
488 12/27/65 13. 1 101 3.07
489 12/28/65 15.2 1o8 113
49o_ 12/28/65 12.9 110 113
491 12/28/65 10.0 105 113
492 12/28/65 13.3 101 log
493 12/28/65 13.8 105 107
494 12/28/65 23.2 90 97
495 12/28/65 15.2 98 107
496 1/03/66 13.6 lo6 110
497 l/o3/66 13.1 105 110
498 1/03/66 16.7 105 110
499 1/03/66 13.1 lo4 110
500 1/03/66 18.1 96 97
50 1/03/66 15.7 99 107
5 1/03/66 18.2 100 107
50 1/03/66 22.0 87 97
5o4 1/03/66 12.5 107 llo
505 1/03/66 20.0 100 lob
5o6 1/03/66 20.0 99 lo6
507 1/03/66 14.8 108 109
508 1/03/66 16.o log 110
509 1/03/66 14.7 101 lob
510 1/o3/66 12.7 105 lob
511 1/021/66 13.1 lo4 116
512 1/04/66 12.2 102 log
513 1/01i/66 17.1 95 103
514 1/04/66 18.5 102 113
515 l/o4/66 15.7 1o6 110
516 1/04/66 16.7 101 107
517 1/04/66 16.7 100 107
s
s
9
C1. 4 ent Tram: America
Tr-: ct N,D -____3p 2 3
Test DDtt-, ry_
No. Tt'at
D(Mn 1 l.i ti . i.rr nr
i:'ne;in(.ers
Jib
UG t t OctoberL, 1966
Sher t 21 )f
Rr;SULT5 OF F-E'LD D.-,J,.:ITY TITS
D ns,t;- Percent
erct nt Ub s,/C_.. Ft . Lb 'Ct Ft MaxLmum
518 1/o4/66 10.11 105 98
519 1/o4/66 16.E 101 107
108
90
935201/o4/66 13.8 - 100
521
522
1/o4/66
1/04/66
21.5
12.1
90
105
97
116
93
go
523
524
1/021/66
1/04/66
16.7
10.5 l99 110
112
go
97
525 1/oli/66 15.5 log 116 94
526 1/o4/66 10.5 104 110
110
95
527 1/o4/66 11.4 106 96
528 1/o4/66 11.7 log 110 99
529 1/o4/66 16.7 102 110
116
93
975301/o4/66 16.3 112
110 91t5311/o4/66 14.9 103
532 1/05/66 13.1 log 110 99
533 1/05/66 15.7 1-05 110 95
534 1/05/66 16.0 108 13-0 96
535 1/05/66 20.9 101 109 93
536 1/05/66 14.8 lob log 99
537 1/05/66 20.3 100 110 91
538 1/05/66 19.5 90 97 93
94539
540
1/05/66
1/05/66
18.3
16.1
91
97
97
103 92+
541 1/05/66 16.9 98 103 95
542 1/05/66 16.1 87 97
107
90
965431/05/66 16.8 103
544 1/05/66 16.5 go l97 96
545 1/05/66 16.7 99
546 1/05/66 20.6 90 97 93
547 1/05/66 19.5 89 97 92
548 1/05/66 18.6 100 107 93
549 1/05/66 14.8 107 103
116
99
945501/05/66 1.2.7 109
551 1/05/66 14.1.E 103 113
12.0
91
985521/05/66 12.7 118
116 95553
554
1/05/66
1/05/66
15.1
li.6
110
115 120 96
555 1/06/66 10.1 118 1-20 98
556 1/06/66 11.7 116 120 97
557 1/o6/66 17.1 98 103 95
r
t
ran-.- c =mot' October,, 1966_..
H 4 ULTS U*., F-_i;_aD 1; , IT i T...."T.';
Lt t _ t..t•f- F . 1:. ._:`-- ti.<.-- .1-.._ _ e f"1',.
fs} M -t Pt tlti C 11 jfj
558 1/o6/66 20.9 92 99 93
559 1/o6/66 19.3 107. log 98 .
560 1/o6/66 17.2 98 103 95
561 1/o6/66 18.5 97 103 94
562 1/o6/66 16.1. 103 log 94
563 1/o6/66 17.0 101 112 go
564 1/o6/66 17.5 107 112 96
565 l/o6/66 11.1 103 log 9L}
566 1/1o/66 13.3 100
103
103
110
97
567 1/lo/66 12.7 94
568 1/lo/66 17.7 97 107 91
569 1/lo/66 16.8 lo4 113 92
570 1/lo/66 11.5 104 107 97 S
571 1/lo/66 15.7 1-03 112 92S
572 1/1o/66 16.8 lo4 113 92
573 1/lo/66 11.0 log 119 92S
574 1/10/66 11.4 105 108 93
575 1/lo/66 13.4 105 l08 96
576 1/1o/66 12. 113 119 94
577 1/io/66 15.4 97 lo4 93
578 1/lo/66 12.0 98 104 93
579 1/lo/66 12.1 101 108 94
580 i/lo/66 13.1 ill 119 93
581 1/lo/66 13.4 102 108 95
582 1/11/66 1-0. 0 100 loll- 97
583 1/li/66 17.4 101 108 97
584 l/11./66 10.5 96 104 2
935851/11/66 5.4 102 110
586 1/11/66 10.5 112 116 97
587 1/11/66 5.9 107 118 91
588 1/11/66 8.8 107 116 92
589 1/11/66 12.1 112 118 95
590 1/11/G j 13..0 110 116 95
591 1/12/66 10.1 log 11-6 94
592 1/12/66 10.5 111 116 96
593 1/12/66 12.6 f 114 117 97
594 1/12/66 1.1.4 108 116 93
595 1/12/66 8.8 107 110 97
596 1/12/66 12.5 114 118 97
597 1/12/66 20.3 98 107 92
4"If AA6N
671'
7-
jw
211 roe t
dill+. f,FC3LUGISi`: '- 1
3W
Beach Leighton & Assoej:ltes
SOUTH BEACH BOULEVA(IO • LA FIAanA, CALIFORNIA 90G31 • (213 G94-1826 • (714) 5261337
June 2, 1971
9`r4 Our Project No. 1324
TO: Diamond Bar Development Company
Attention:- Air, Ben Molina
FR0,14: . F. Beach Leighton & Associates
SUBJECT: Preliminary Geologic Investigation' of Tract 30289, Equestrian Estates, Diamond Bar, County of Los Angeles
Introduction
This report summarizes the engineering geologic aspects of Stage IandStagelIofageologic -soils study of the subject property. The soils
engineering portion is being provided by Moore & Taber.
The chief purpose of Stage 1 was to isolate the lots about which geologicquestionshavebeenraisedinpreviousgeologicreports. Stage II consisted
of subsurface exploration primarily concentrated in one area where questionshadbeenraisedbypreviouswork.
This report treats these questions concerning daylighted bedding and theexistenceofslumps, creep and landslide material. The area probed in Stage IIliesalongCross -Section AL -AL' (see accompanying Revised Index Hap of Lots)
Existing graded areas are not within the purview of this investigation,
as rough grading has been approved by the previous consultants and the County - of Los Angeles and no major question marks or problems have come to our atten-
tion.
Accompanying Illustrations and Supporting Data
Revised Index Map of Lots (attached to back of report)
Revised Cross -Section AL -AL' (40-scale)
Preliminary Geologic Map (Sheet 4 of 5 and 5 of 5 spliced together)
Boring Logs 1L through SL
IELO OFFICES: AgorrralThousind O.rls Laguna Hills San E:rnardino213) 809-2472 17141 83a 3G11 17141 884-1838
Transamerica - Eques 'ian Estates - Phase II Tune 2, 1971
Chief Steps in Stage I
1. Field reconnaissance
2. Collation.and tabulation of all reports received on the subject tract,
3. Transfer of geologic data collected by others to the 40-scale grading
plans; these data were color keyed.
4. Geologic review of lot by lot reports and other reports received.
S. Preparation of an index map showing those lots with no significant ,
additional subsurface exploration. -lots with additional subsurface
exploration, lots approved by the County of Los Angeles, and lots
previously treated by others that were not included in the scope of
this report.
Chief Steps of Stage II
1. Staking of backhoe trench locations and boring locations in field
and field measurements of cross-section line AL -AL' to update this
profile and base it on existing conditions.
2. Preparation of seven backhoe trenches.
3. Drilling of five holes (total depth 44 feet) - (three borings were
drilled in Lot 31 concurrently with this subsurface exploration).
4. Logging of pits and borings within the holes and the backhoe trenches;
the latter were reviewed by Mr. Doug Brown of Moore & Taber.
S. Collection and testing of soil samples by Moore & Taber. Samples
were collected by Moore & Taber and this.office.
6. Revision of Cross -Section AL -AL' to show detailed geology and pit
and boring locations.
7. - Preparation of stability analysis by Moore & Taber from Cross -Section
AL -AL' in Lot 20 and in Lots 32-33.
F.Alvach I-eiglilon & Associates, Inc.
Transamerica - Equestrian Estates - Phase II .Tune 2, 1971
SUMIN1ARY OF F:INDINGS, STAGES I AND II
Stage I
1. Previous geologic reports were reviewed to determine the extent of
the questions asked by others concerning specit-4•lots within the
tract.
2. No major questions have been raised by others on Lots 2-7, 24-26,
38, 40, 41 48, 50 and 60-61 (16 lots). Based on the information
provided in the previous reports, a geologic review of building
plans or grading plans is all that is geologically anticipated
unless these plans incorporate re -grading of the pads to the extent
that it will be contrary to previous recommendations, which may
result in an unstable condition.
Stage II
1. Bedding planes daylight in the natural slope of Lots 20 and 21 below
the graded pad areas and above the Equestrian Easement. Bedding
attitudes in this portion of the slope N10-45°E and dip 7-8'W.
Bedding attitudes at the top of the slope in the vicinity of Lot 20
become flatter with depth (see Cross -Section AL -AL' and Preliminary
Geologic Map) .
2, Moore & Taber has prepared a stability analysis of this portion of
the slope and reportedly the analysis indicates a favorable factor
of safety (1.5 or greater) for this portion of the slope.
3. Soil and weathered bedrock locally exist to a maximum depth of 4 to
5 feet. Caliche stringers paralleling bedding generally exist at
this depth.
4. The bedrock sequence is generally consistent throughout the length
of the slope, which has been reviewed'(see'Cross-Section AL -AL').
Units of sandstone and siltstone are traceable in the subsurface.
Locally, clay seams exist which are parallel to bedding.
5. No deep-seated slump -creep was exposed in the drilling program. A
gnarled zone was mapped in the borings but is the result of regional
uplift rather than downslope landsliding.
6. Ground water was exposed in Boring 4 approximately 24 feet below
natural ground. (See Cross -Section AL -AL'). Reportedly, subdrainage
has been provided below the existing fill in this area.
7. Bedding planes do not daylight in the natural slope below Steeple --
chase Lane in the vicinity of Lots 32 and 33.
F. Beach 1xinizlon & Associales, Inc.
Transamcric.a - hqucstri=in Estates - Phase I1 tune 2, 1971
S. Bedding planes did apparently daylight in the natural slope now
buried by controlled fill placed by others in Lots 32 and 33.
9. A questionable landslide exists at the western margin of Lots 32
and 33. (See Cross -Section AL -AL').
10. No rock creep was exposed on the periphery of the graded building
pad of Lot 70.
11. It is not believed geologically necessary to comment or to probe
Lots 9--11,`66-68 or the other graded portions -of the tract, since no
specific questions have been asked,about these areas, and grading has
been approved by former consultants and the County of Los Angeles.
4-
F. lieach Lcighion & Acsociales, Inc.
Transamerica - Equesti a Estates - Phase II June 2, 1971
CONCLUSION AND RECOIDIENDATIONS
Conclusion
Based on the findings of the Stage II investigation, major questions raised
by others can be analyzed geologically and soils engineering -wise by a prudent
subsurface exploration program. 'Once the major questions have been answered,
then lot by lot reports required by the County of Los Angeles can incorporate
these findings and be based on the individual building and/or grading plans.
Recommendations
1. The subsurface exploration program for Stage 11 should be continued
in the other areas of the tract where major questions have been
raised. These questions should be analyzed and evaluated by the soils_
engineer and geologist.
2. The questioned landslide along the western tract boundary should be
evaluated since Moore & Taber has indicated the final stability
analysis of the natural slopes below Steeplechase can not be fully
completed until this slide has been evaluated.
Respectfully submitted,.
L wrence R. el
Engineering Geologist (EG 5$4)
cbe
Distribution: 2-
Diamond Bar Development Co. (1)
Attention: Mr. Ben Molina
Moore & Taber (1)
Attention: Mr. Doug Brown
See Abl)rcviation List :a:ttachcd)
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INDEX MAP
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LOTS
6-1-71
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LOTS REQUIRING NO SIGNIFICANT ADDITIONAL SUBSURFACE
EXPLORATION, PROVIDED FUTURE BUILDING PLANS DO
NOT INCLUDE ADDITIONAL GRADING
LOTS REQUIRING ADDITIONAL GEOLOGIC AND SOILS
INVESTIGATIONS
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EXPLORATION (QUESTIONS BY OTHERS)'
LOTS PREVIOUSLY TREATED BY OTHERS AND NOT k
INCLUDED IN THIS INVESTIGATION`"
F-F LOTS APPROVED BY THE COUNTY OF LOS ANGELES
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Borings Total 5) -
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Total 8;_.one old pit Lot 22)
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TABLE OF CONTENTS
1. INTRODUCTION Page 1
2. CONCLUSIONS Page 1
3. RECOMMENDATIONS Page 2
TECHNICAL SECTION
1. REGIONAL GEOGRAPHY Page T1
2. LOCAL GEOGRAPHY Page T1
3. STRUCTURAL GEOLOGY Page T2
4._ DRAINAGE
A. Surface Page T2
B.Subeurface Page T3
5. VEGETATION Page T4
6. EARTH MATERIALS
A.Fill Page T4
B.Soil Page T4
C.Bedrock Page T4
7. MASS MOVEMENT Page T5
TO: Transamerica Development Company
2900 South Brea Canyon Road
Diamond Bar, California
FROM: James E. Slosson and Associates
Consulting Geologists
15373 Valley Vista Boulevard
Sherman oaks, California
SUBJECT: Geologic Report for Lot # 16, Tract #30289,
a portion of Equestrian Estates. Diamond
Bar, California.
The purpose of this report is to render infor-
mation concerning geologic conditions in the vicinity of
Lot # 16. Consideration will be given to: 1) the general
stability of the site and 2) basic consideration for the
design and construction of a single family dwelling on the
site.
All of the information, conclusions, and recom-
mendations contained herein are to be considered profes-
sional opinions based on observations in the field and
from the literature.
CONCLUSIONS
During grading of Tract #30285, Lot #116 was inspect-
ed by the Engineering Geologist and Soils Engineer. Recom-
mendations of the consultants were followed and the Los An-
geles County grading requirements were satisfied. Lot #1_6
is a feasible building site for a single family dwelling.
2-
pith development of Tract #30289 Lot #16 has been made
stable and should remain so if the following recommenda-
tions are considered.
RECOMMENDATIONS
1. structures should be provided with eave
trough drains which will direct water via
paved surfaces or pipe to the street.
2. All graded surfaces where the soil cover
is removed should be provided with impermeable
blanket seals.
3. Any west facing cuts made to provide a
building surface should be designed at 4:1
or stabilized.
4. Any proposed structure(s) should have their
footings designed to withstand some possible
differential settlements within the founda-
tion materials.
5. All internal drains should be connected in
accordance with Los Angeles County code re-
quirements. No cesspools should be allowed.
6. Any swimming pool design should be reviewed
by both the Engineering Geologist and the
Soils Engineer.
7. The foundation design of the structure(s)
should be reviewed by the Soils Engineer
and the Engineering Geologist.
B. Any proposed grading should be reviewed and
approved in accordance with Los Angeles
County code requirements. This should in-
clude the review and approval by the Engin-
eering Geologist and the Soils Engineer as-
signed to the tract.
3-
9. The drainage from the canyon traversing
Lot 416 should be diverted via drainage
devices, such that no ponding behind or
undermining of any proposed structure(s)
will occur. The drainage should not flow
over graded surfaces where the natural soil
cover has been removed, except via paved
surfaces.
Michael E. 8ryan
gineer'
1-2-
logiat
s on
supervising Engineering Geologist
une 3, 1966
cc: Donald R. Warren Company
Dutch Holzhauer Engineering, Inc.
NOTE: See attached Technical Section, Tl-T5,
for detailed geologic data.
Tl-
Technical Section
Technical Section of the Geologic Report for Lot #16,
Tract +F30289, a portion of Equestrian Estates, Diamond
Bar, California.
REGIONAL GEOGRAPHY
Lot #16 is situated within Tract #30289 of the
Equestrian Estates Tract, Diamond Bar, California. The
community of Diamond Bar, California is located in the
northern portion of the Puente Hills approximately 10
miles southeast of Pomona, California. This community
may be reached from Los Angeles via the San Bernardino
Freeway south to Holt Avenue, thence proceed southwest
on 5th Street, which turns into Brea Canyon Road. The
nearest main thoroughfare to Tract #30289 is Diamond
Bar Boulevard, which can be reached via Brea Canyon Road.
Diamond Bar Boulevard trends approximately north -south
along the western boundary of Tract #30289. The tract
is bounded on the north, south, and east by pndeveloped
land under the same ownership. Tract #30289, including
Lot #16, and the surrounding lands were previously used
for cattle and sheep grazing.
The Puente Hills are bounded by the Pomona Val-
ley on the northeast, the San Jose Hills on the northwest,
the Los Angeles Basin on the southwest, and the Santa Ana
Mountains on the southeast. Physiographically, the Puente
Hills are composed of northeast -southwest trending major
ridges and intervening valleys. A trellis drainage pat-
tern is illustrated as the tributary canyons meet the
major drainage courses at right angles. This pattern
is typical in areas which have been affected by folding
and tilting. The Puente Hills have been subjected to
intense folding and faulting in the past. The major
drainage courses were established subsequently along rock
contacts, in less resistant rock units and, in some cases,
structurally weakened zones. The most outstanding struc-
tural features in the area are the Whittier and Chino
faults, trending northwest -southeast, indicating a struc-
tural relationship between the Puente Hills and the Santa
Ana Mountains.
LOCAL GEOGRAPHY
Lot #16 is situated in the southwest portion
of Tract #30289 approximately 415 feet southeast of the
intersection of Steeple Chase Lane and Shadow Canyon
T2-
Drive. It is bounded on the west by Steeple Chase Lane.
The physiography of Tract #30289 correlates well with the
physiography of the Puente Hills. Tract *30289 is situated
on the west slope of a major north -south trending ridge
paralleled by Brea Canyon to the west. Minor ridges and
stream canyons trend at right angles to this major ridge.
Lot #16 is situated across a northwest trending minor
stream canyon. The north portion of the lot is occupied
by a minor ridge. The natural slope of this ridge has a
gradient of 12fdegrees.
The rock strata generally dip gently toward Brea
Canyon (northwest) and vary from 6 to 19 degrees. Numerous
landslides and slump -creep features existed within Tract
30289 prior to grading. Rock flowage and soil creep have
given the ridges a rumpled look and appearance of having
flowed. Natural slopes within the tract dip from 10 to
30 degrees. Flat topped ridges capped by resistant sand-
stone beds are a common feature.
STRUCTURAL GEOLOGY
The general structure in the area of Tract #30289
consists of a northwest dipping homocline. Within Lot #16
this homoclinal structure has been somewhat complicated by
an ancient slump -creep feature. The materials affected by
this feature have been contorted and crenulated. However,
the average dip and strike of bedding planes conforms with
the general local structure. The slump --creep feature will
be discussed in detail under the heading "mass movement".
DRAINAGE
Surf ace
The major portion of the surface runoff in the
vicinity of Lot #16 will be in the form of concentrated
flow draining via the stream canyon traversing the lot.
This water will be intercepted and diverted to the north-
west via Steeple Chase Lane. Steeple Chase Lane will con-
duct the water to a storm drain system within Brea Canyon.
During the 50 year storm of November, 1965 field observa-
tions indicated that water draining via the minor stream
canyon through Lot #16 was small in quantity, but not in-
significant. It is therefore recommended that this drain-
age course be considered during future grading and con-
struction on this site. This water course should not be
T3-
obstructed in such a way as to cause ponding behind or un-
dermining of any proposed structures. It should be diver-
ted around the building surface in such a way that the wa-
ter will not flow over graded surfaces where the natural
soil cover has been removed, except on paved surfaces.
Although excellent surface drainage appears to
exist all around the lot, extensive alkali (mineral) depos-
its near the surface indicate some past downward percola-
tion of surface water. Evidence observed in the field in-
dicates easy erodibility of existing rock materials within
the area.
The lot could be exposed to water draining from
the roof of any structure anticipated for the lot. Thus,
cave trough drains which, in turn, drain directly to the
street are recommended. Any graded surfaces where the na-
tural soil cover is removed and that will be exposed to sur-
face water are susceptible tb infiltration by surface water.
This includes those portions of building surfaces not en-
tirely covered by the structures or a paved surface. Im-
permeable blanket seals (compacted fill) would aid in re-
ducing surface water infiltration in these areas.
Subsurface
No active springs were noted on Lot #16 or within
Tract #30289. However, extensive evidence of past ground
water percolation is common. Slides and creep features
noted within Tract #302B9 indicate water retention or per-
colation. These features (slides, creep) usually occur in
the presence of excessive moisture. Abundant alkali (min-
eral) deposits along bedding planes indicate past percola-
tion of ground water.
The buttress fills to the west of the lot above
Steeple Chase Lane have been provided with subsurface
drains. The purpose of the subdrains mentioned above is
to,primarily, prevent the collection of moisture between
the compacted fill and bedrock interfaces. Thecae subdrains
should be more than adequate to handle the subsurface wa-
ter in the vicinity of Lot #16. However, due regard must
be taken to insure that excessive water does not pond on
the surface of Lot #16 and then in turn infiltrate into
the fill or bedrock (see recommendations).
T4-
VEGETATION
The regional vegetation consists of varying
amounts of wild grasses (oats, mustard, etc.), live oak,
California holly, chapparal, sage, sumac, and poison oak.
wild grasses compose the majority of vegetation within
Lot 4016. There are a few small live oak trees within the
lot boundaries.
EARTH MATERIALS
Fill
The north and south termini of two compacted
fill buttresses occupy the west boundary of Lot #16 above
Steeple Chase Lane. These fills were benched mnd keyed
into competent bedrock and tested and approved by the Soils
Engineer. The fill materials are composed of silt and
sand of the La Vida member of the Puente formation.
soil
A dark brown, adobe
at an average thickness of 1
tion is found in the bottom
the lot.
Bedrock
soil overlies the entire lot-
to 5 feet. The thickest sec -
of the stream canyon traversing
The bedrock within Lot #16 consists of siltstone
and shale of the La Vida member of the Puente formation of
upper Miocene age. Two different types of siltstone are
noted within the La Vida member: 1) a brown -gray to gray,
soft, micaceous siltstone and 2) a white to gray, platy
siltstone. Thin interbeds of tuffaceous material were
noted along bedding planes and within fractures. Within
Tract #30289 these units are contorted and crenulated indi-
cating ancient plastic reaction to stress. Abundant secon-
dary alkali (mineral) deposits suggest percolating water
conditions.
Within Lot #16 these rock units are highly con-
torted due to an ancient slump -creep feature. The bed-
rock as a whole (also within the slump -creep feature) has
an average downsiope dip of`:13fdegrees to the west (see
cross section). This average dip is steeper than the aver-
age slope gradient thus there are no daylighted bedding
planes associated with the lot.
T 5-
T;_ area Jesi 'nated C.3C on thf- geologic map
featurc-s illustrt,ting roc:: creep,
tc a mayim,-1-o depth cf 30 feet within this
i :_. :' ,e ;;tar.isnu, c -pth to which the disturbed mater-
i=' itliin Lot z 16 is interpreted to be 15 to 20
pith the construction of the buttress above
Sh-ar': C.,n;ren Drive and along Steeple Chase Lane and the
imoroved drainage brought about by design and construction
c r it is felt that this material has been ade-
ru to _,-:rubi3 izEC] for residential development. The recom-
menas_ dionF; concerning drainage contained in the front of
this report should be followed, since the introduction of
excessive water into the disturbed materials must be avoid-
ed.
It is further recommended that any proposed struc-
tures have their footings designed to withstand some pos-
sible differential settlements within the foundation mater-
ials.
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M•4P Tr. 30289
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LEGEND -
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V.L- Strike and dip of beds J
1 Contorted beds
Inferred fault
Inferred concoct
Direction of movement
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