HomeMy WebLinkAboutCT 81-21; LA COSTA VALLEY UNIT 5; GEOTECHNICAL INVESTIGATION; 1981-02-20I
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LEIGHTON and ASSOCIATES
SOIL ENGINEERI NG TESTING GEOLOGY
February 20, 1981
TO: L & M Professional Consultants; Inc.
1224 Prospect Street
La Jolla, California 92037
ATTENTION: Ms. Henri Lagatella
SUBJECT:
ENVIRONMENTAL SCIENCES
Project No. 4800670-02
Geotechnical Investi'gation
Proposed Condominium Development
La Costa Vall ey Uni t No." 5, Lots 229 through 232
Alicante Road and Altisma Way
Carlsbad, California
Gentlemen:
In accordance with your request, we have performed a geotechnical investiga-
tion of the subject property. The purpose of the investigation was to determine
the suitability of the geologic and soil conditions at the site in relation to
the planned condominium development.
Our investigation consisted of the following:
• Review of published and unpublished geologic information relevant to the
site and previous geotechnical reports for the site by Benton Engineering,
Inc.
• Geologic mapping of the site.
• Subsurface investigation consisting of logging and sampling of nine large
diameter test borings.
• Laboratory testing of samples collected during the subsurface investigation.
• Engineering and geologic analysis.
• Preparation of this report.
7290 ENGINEER ROAD, SUITE H, SAN DIEGO, CALIFORNIA 92111 (714) 292-8030
IRVINE! • \""1ESTLAKE/VENTURA • DIAMOND BAR/WALNUT. SAN BERNARDINO/RIVERSIDE· SAN DIEGO
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4800670-02
Geologic mapping was accomplished on a 20-scale topographic map of "La Costa
Condominiums ll by Pountney & Young, Inc. The.topographic base for the Geo-
technical Map, Plate 1, is a 20-scale IIGrading Plan for La Costa Condominiums"
prepared by Pountney & Young, Inc., dated January, 1981.
The subject site was graded between May and October 1970 under the supervision
of Benton Engineering, Inc. following a "Pre·liminary Soils Investigation., La
Costa Valley Un4t No.-5 11 prepared by the same firm and dated January lQ, i.197;0.
A compaction report entitled "Final Report on Compacted Filled Ground, Lots
229 to 242, inclusive, Lots 244 to 250, inclusive, and Certain Street Areas,
La Costa Valley Unit No" 511 was issued November 4, 1970 by Benton Engineering,
Inc. upon completlon of grading.
Accompanying Illustrations and Appendtces
• Figure 1 .-Index Map
• Plate 1 -Geotechnical· Map and Cross-Sections
• Appendix A -Boring Logs B-1 through B-9
• Appendix B -Results of Laboratory Testing
• Appendix C -Generalized Earthwork and Grading Spectfications.
Site Description
The irregular-shaped site, encompassing approximately 5 acres is located on
the north side of San Marcos Creek· Valley (see Index Map," Figure 1). The site
is bounded on the north by Caringa Way, on the east by Altisma Way, on the south
by Alicante Road, and on the west by ~xisting development. The property con-
sists of four, roughly equally-sized, graded lots.
Prior to grading the site was situated on a moderately sloping hillside adjacent
to a south-flowing tributary of San Marcos Creek. Grading terraced the hillside
and filled portions of the drainage course. At present the site consists of a
relatively flat terrace bounded on the south by a 30 to 40-foot high 1.5 to 1
cut and fill slope.
The eastern and southeastern slopes (primarily fill) are severely eroded with nu-
merous gullies to 10 feet in depth. Erosion of the teirace edge is ch~racterized
by gully heads and piping. .
Surface drainage on the eastern half of the site (Lots. 229 and 230) is to the
east over the existing cut slope and to the south through a concrete IIdown
drainll to Alicante Road. The western pOrtion of the site drains to a storm
drain in the southwestern corner of the site.
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480670-02
2000 o 2000
feet ----scale
GEOTECHNICAL INVESTIGATION
PROPOSED CONDOMINIUMS
LA COSTA VALLEY 'UNIT NO~ 5, LOTS 229 THROUGH 232
CARLSBAD, 'CALIFORNIA
Basis: U.S.G.S. Encinitas Quadrangle (7.5 min)
LEIGHTON & ASSOCIATES
fIGURE 1
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4800670-02
Proposed Development
It is our understanding that three-story condominium buildings with first level
parking are planned for the site. It is further our understanding that the pre-
s~nt single terrace will be regraded_ tOi!form two or three terraces which will
step down towards the south. Grading of the terraces would be accomplished by
excavation and export of soil. Slopes would be eliminated or reduced and re-
taining walls would be constructed to serve as grade separations between terraces.
Subsurface Investigation
Nine test borings ranging in diameter from 12 to 36 inches were drilled to depths
of 23 to 42 feet in order to evaluate the subsurface conditions at'the site. The
approximate boring locations are shown on the Geotechnical Map~ Plate 1. The
borings were logged during drilling and downhole logged after drilling, and repre-
sentative bulk and undisturbed 'samples collected for laboratory analysis. Logs
of the borings are pr~sented in Appendix A.
Laboratory Testing
Laboratory testing was performed on selected bulk and undisturbed samples obtained
from the test borings and included moisture-density, maximum density, expansion
index, direct she'ar and consolidation. Results of the moisture-densisty tests
-are -shown on the boring logs. The remaining test results are presented in-Appendix
B.
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4800670.-0.2
FINDINGS
1. Site Geology
The subject site.is underlain by three geologic units. From oldest to young-
est they are as follows: ' ,
• Delmar Formation (Td)
• Old alluvium Coal)
• Compacted fill (fill)
Delmar Formation: Underlies the entire site and is exposed in the cut slopes
along the eastern and southwestern corners of the site. This bedrock unit
consists of interbedded clay, silty clay, and clayey and silty sand. Bedding
within the unit is lense-shaped with individual lithologies not traceable
across the site. In general, the Delmar Formation on the site.dips 5 to 20
degrees to the southwest. The existing south-facing cut slope is considered
stable with 'respect to the exposed bedding conditions.
Old Alluvium: Encountered in B~rings B-1 thr.ough B-5. The materials consist
of dense, poorly-graded, clean, medium to coarse-grained sand and thin inter~
beds of sandy silt. Colluvial soils composed of dark brown silt and silty
clay overlying the alluvium were encountered in Borings B-2 and B-3.
Compacted Fill: Placed in the southeaste~n portion of'the site and loca~ly
along the top of the slope bounding the southern edge of the lots. The
approximate location of the fill is delineated on the Geotechnical Map, Plate
1. These materials consist ,of silt, ,silty sand, and sandy clay placed and
compacted under the supervision of Benton Engineering, Inc. in 1970.
2. Soil and Bedrock Conditions
The alluvial and fill soil and bedrock materials (Delmar Formation) encountered
at the site are generally dense, moderately to well compacted or well consoli-
dated and are considered generally favorable with respect to the proposed de-
velopment.
The compaction of existing fill soils should be further verified by additional
testing at the time of construction. Up to 2 feet of uncontrolled clay fill
is reported as having been placed on portions of Lots 229 and 230 subsequent
to previous grading operations. '
Portions of the on-site soils are clayey and expansive and will require
special foundation design where exposed at finished pad grade.
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480067Q-Q2
The bedrock materials at the site, consisting of layered sands and clays,
are generally inclined such as to vary from neutral to approximately 5 de-
grees out-of-slope with respect to south-facing cuts. As such, earth but-
tress construction would not be necessary unless the bedrock inclination .
is found during construction to be locally greater or unless a particularly
weak layer; e.g~, plastic clay, ,is encountered. However, the necessity of
some buttressing should be anticipated for south-facing cuts or excavations
for retaining walls.
3. Site Hydrology and Groundwater
Surface runoff on the eastern half of the site is directed toward the cut
and fill slopes in the southeastern corner of the site. As a result, the
runoff has created numerous pipes and gullies at the top of the slope.
Several of the larger gullies extend to the base of the slope. The severe
gullying appears confined primarily to the cut slopes exposing silt and sand
of the Delmar Formation on the easternmost portion-of the site. Piping at
the top of the slope is more extensive within the fill materials. Where
runoff is controlled in the western portion of the site the effects of erosion
are minimal.
The southern slope is drained-by concrete terrace nr bench-drains with a 20-
foot vertical separation. The bench drains do not extend to-the east-fating
slope.
No groundwater was encountered durjng the subsurface investigation. Grading
may expose relatively permeable sand of the Delmar Formation or alluvium.
If irrigation water is-allowed into these materials, the southerly dip of
the formational ~and may allow migration of the water to the existing south-
facing:cut slope creating a potential for seepage.
The interbedded sand and clay bedrock conditions (pervious and impervious
layers) at the site-are expected to cause lateral as well as downward migra-
tion of groundwater subsequent-to development. Installation of well-designed
back-drainage systems will be necessary for retaining walls and it should be
anticipated that pDrtions of cut-slope faces_will become wet and will remain
saturated after development unless replacement fill, buttress construction
-or other remedial measures are undertaken.
Faulting and Seismicity
The two principal seismic considerations for most properties are surface
rupturing of earth materials along fault traces and damage t9 structures
and foundations due to seismically-induced groundshaking. No active or po-
ten.tially active faults are known to transect the site. The potential for
damage due to fault surface rupture is considered nil.
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480.o.67Q-0.2
The two faults considered most likely to produce significant groundshaking
at the site are the Elsinore "and the Coronado Banks faults. The seismic
effects of "ground shaking can be mitigated by adherence to the provisions
of the Uniform"Buil9ing Code or Structural Engineers Assoc.iation of California.
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4800670-02
CONCLUSIONS
1. From a geotechnical standpoint it is our opinion that the site is suitable
for the proposed development provided the recommendati"ons contained in the
following sections of the report are incorporated.within the design and
construction of·the project •
. 2. No active or potentially active faults are known to transect the site.
The primary seismic hazard is groundshaking due to the effects of an
earthquake on major active faults in the region •.
3. Existing fill soils encountered in ·our. test borings were found to bemod~r
ately to well compacted. Fill compaction should, however, be further verified
by inspection and, if necessary, testing at the time of construction.
4. South-facing cuts or excavations for retaining walls should· be evaluated for
stability during construction and in the event of adverse geologic conditions
may require stabilization by earth· buttressing or other remedial measures.
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4800670-Q2
RECOMMENDATIONS
1. Site Earthwork
Site earthwork should proceed in accordance with the provisions of the
General Grading and Earthw~rk Specifications presented in Appendix C.
Excavations of the on-site soils can be accomplished using conventional
earthmoving equipment. As excavation proceeds in the existing fill areas
of the site; evall:Aation and, if necessary, testing of the existing fill and
under lyi ng natural .ground should be performed by the geotechni ca 1 consu 1-
tanto If unsatisfaGtory conditions are exposed (although not. anticipated),
overexcavation and recompaction beyond and planned excavation depths should
be performed as directed by the geotechnical consultant.
-The moderate to deep erosion gullies existing tn the slope areas of the
site will likely be removed by proposed excavation. The grading plans,
once completed, should be reviewed to verify that gulley areas will be
removed., and if the gullies are not completely removed by planned excavations,
. remedial grading will be necessary.
After removal of brush from the project area, site soils are, in general,
considered suitable as fill material. All excavations for slopes or retain-
ing walls should be inspected by the geotechnical consu1tant and where adverse
geologic/soil cond·itions are exposed, earth buttressing or other remedial
measures should be performed as directed by the geotechnica1 consultant. The
grading plans should be reviewed in advance of grading to evaluate areas where
the 1i-kelihood of buttress construction is greatest. Typical buttress details
are presented in Appendix C.
It may be desirable to stockpile the more sandy soils encountered during ex-
cavation for use as wall or trench backfill materials.
2. Slopes!
Cut and fill slopes should be constructed no steeper than 2 horizontal to 1
vertical~ Fill slopes should be compacted by sheepsfoot rolling or over-
building and cutting' back. Appropriate surface drainage 'features and land-
scaping should. be p~ovided_to ~~nim~~ _any potential for erosion.
3. Foundatio'ns
.8 Footings
Conventional shallow footings are recommended for support of the pro-
posed Gondgminiums. ~Qntinuous a~d individual footings sho~ld be a
minimum of 12 inches wide and 18 loches deep and may be deslgned !o~
an allowable soil b~aring pressure of 3000 pounds per square foot:Wlth
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4800670-02
a one-third increase for all loads includiR,g wind or seismic. Where
expansive soils occur within the upper 3 feet of graded building areas,
footings should be reinforced and/or deepened to minimize the po~entiaf
for distress resulting from expansive, soil pressures.
I: Floor Slabs-On-Grade'
Floor slabs~on-grade shpuld be a minimum for four inches thick (nominal),
and in living areas, should be underlain by a sand blanket (2-inch thick
minimum) and a plastic membrane. Floor slabs to be placed over expansive
subgrade soils should be reinforced by welded wire mesh and the subgrade
moisture should be increased, if necessary, such that the moisture con-
tent is equal 'to or greater than optimum, prior to concrete placement.
I Identification of Expansive Soils
Expansive soils where occuring within the upper 3 feet of building areas
after'grading~ should be tested for swell potential and evaluated by the
geotechnical consultant. Specific foundation'recommendations on a build-
ing by buil,d'ing basis should be detennined based on evaluation of the
test results.
I, Footings Near Slopes'
hooti.ngs near slopes should be set back from the top of the slope or
de'epened such that the bottom outside edge of the footing will be a mini-
mum of 8 feet (measured horizontally) from the slope face.
I ,Passive Resistance
The allowable passive pressure for resisting lateral structure movement
may be assumed to be equivalent to the pressure ,of, a fluid weighing 300
pounds per 'cubic foot. The coefficient of friction between concrete and
soil may be assumed to be 0.35 for resistance to horizontal movement.
4. Retaining Walls
Retaining walls free to deflect at the top and resisting lateral earth pres-
sures from on-site soils should be designed for an equivalent fluid soil pres-
sure of 40' pounds per cubic foot for level backfill and 60 pounds per cubic
foot for 2 to 1 sloping backfill cond·itions.' Walls restrained from movement
at the top (e.g. basement walls) should ,be designed for an equivalent fluid
pressure of1'50~~,pounds per cubic foot for level backfill and 65 pounds per
cubic foot'for 2 to 1 sloping backfill. Any additional surcharge pressures
should be added to these values.
Wall foundations may be design~d for. the allowable soil bear-ing values pre-
sented previ ous" y for bu 11 d i hgfounda t ions.
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4800670:::-02
Walls should be properly drained with graded filter material and perforated
pipe placed behind the wall to prevent butldup_of hydrostati'c water pres-
sures. Basement walls should be fully waterproofed.
5. Pavements
Pavement design should be performed on the basis of R-value testtngof ex-
posed subgrade soil conditions once the site has been brought to rough
grade.
This opportunity to be of service is sincerely appreciated. If you have any
questions, please call.
MRO/DLH/gb
Respectively:.
A1~£~
Martin R.··Owen, RCE 23155
Chief Geotechnical Engineer
~~~
Dennis L. Hannan, CEG 953
Chief. Engineering Geologist
Distribution: (5) Addressee .
(2') Pountney & Young, Inc.
(1) Ho~er Delawie Associates, AlA
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APPENDIX A
LEIGHTON and ASSOCIATES
INCORPORATED
GEOTECHNICAL BORING LOG
I Date_---=-1-o~j~6j-8-0.,_·-. __ Drill Hole No. -----------'---B-1 Sheet 1 of 1 -.:;:...--
Project No. 4800670-02 Project Name L & M La Costa Valley Unit No.5 I Drilling Co. Morrison Drill ing Type of Rig, ___ B_uc_k_e __ t_A_u~ge_r_--__ ---
Hole Diameter 2411 Drive Weight __ --'-.......... ---------------'-Drop-----in.
Elevation Top 0 0 e Re • or atum I f H 1 -+74 I f D MSL
I 0
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~ -:-:-'::": .. '.~~ -.: :#' ..... " •. .e ........... .. "-. .... '.-;-=.::.:..: ' .. -It ..... !,. ,-" · .... ~ .. '-.
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• t .' ,t.t ,t. B:
I 5 j:' ;~ N30W ", '~: , .. : 12W
.... t, .. ". : .. --"
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-=;==:=-B: _ . N85W
I --12S
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SM
GEOTECHNICAL DESCRIPTION
Logged By LV
Sampled By ___ -=L::..::V~ ______ _
fILL: Light gray.,.brown, damp, dense, very fine
silty sand
SM-NATURAL GROUND: Dark gray-brown, moist, dense,
SP very fine silty sand to fine sand
ML Lenses of gray, moist, silt to slightly sandy
$ilt
SP Gray-brown, mottled orange, damp, dense, fine
sand, friable
I J.~~ : . . .' : ...
•• -r-o ~~.,.~~~,-.,~~~--+---H---+----+---··-r~S~P-r~L~i-97h~t-g-r-a-y--7b-r-ow-n-,--d~a-m-p-,~d~e-n-s-e-,-m-e-d~i-u-m-f~i~n-e-s-an-d~;
I -:'~":-, ~:~: with occasional 2" diameter gravel. _.
15-Q":o; .. , " ' .. ' Grades to fine, medi urn sand @ 151 I = . :\)\~.; Becomes interbedded in coarse sand @ 15' -20'
.... " ., . . .. . . B'
I ....;::. : .:: N ~E
••• " .J.) -' ... ,: "." SW • • • .. , .. II{ ... 20 --.. ~ ; •. ',
1 ,' .. ~' .....; .' .-
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-••• 4. · '. . I
., ,
-
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. SP-Light· gray":'brownjorange-brown, slightly moist sc to moist, slightly gravelly, medium sand with
some clay bi"nder ..
Total Depth: 23 Feet
No groundwater encountered
No caving
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1--=:::-, ===='::::::::::::1 :::::1 1:::::::=' ::::::::::::::::::::::::==========================~;::::=t
l:~~GHT9N 9ng A$.SOCIATES
GEOTECHNICAL BORING LOG I Date __ ~10;..L./-,-6<...:/8:...:0~· .----Drill Hole No. B-2 --=-..;=-----Sheet 1 of 2 ------
Project Name L & M La Costa Valley Unit No.5 Project No. 4800670-02 I Drilling Co. Morrison Drill ing Type of Rig. __ Bu_c_k_e_t-Ar:.~'g::...e_r ____ ----_--,---
Hole Diameter 24" Drive Weight 2,300# to 25 1 ,1,450# to 50 1 Drop 12, in. I Elevation Top of Hole ±75 I Ref. or Datum MSL
. ." ..~ . .n~ o G) ,g ~o· .,.. ~ +oJ Ill' ..... '"0 ..... III 11)"""'" s:: as CI) .t: bO :3' G) ~ 0 S::lf..I .3 G),...... ~u p.. 0 .~.g!! ~ ~ G) U III +J o~ U • Logged By LV cd...:! ... f-op..~,.... Qp.. ..... s::.....,.CI) J.t +oJ ~~Q) '-' 00 ~.
GEOTECHNICAL DESCRIPTION
I
C) ~ ~ p.. ~' ,;: U '8::> Sampled 8y ___ -=L:..:V_-------
~on.==t====~==~;=~==+==Q===t====4=CI)='-'=4==================================~====~rl .:,,<+.7-: <D SM FI LL: Li ght gray.,. brown, damp, dense, s i 1 ty I -:?:::>':. ~ 8 112.7 6.0 fine sand
ML Dark gray ... brown, moist, medium dense, fine
sandy silt -' -I
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5~~~~---+--~--~----~--~---+--------------------------~-----------+i j:'=':':::-: SM .... Dark brown, moist, dense, silty fine sand
:~'. ML to ftne s'andy s·t1 t .. 3 7 105.8 15.2
J : :.-: : ::. :>:.
.~':;::::,
_,0" •• "0 .... -,:',: :, :::: I
.. II,.." ..
I .. ~ 10-,,: ," ':' ...... . ... . .
I
...,..,...,...,
-'.~
, "
-~ -':'::::;: 115-:~" ~.:
I -~ ......
-~' .. ~",
_ I v-vv..' .. , · --.., -,:,,::-:', · . . I
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20---.. ............ ""· .
, , .. ~.
-.~
'--', ---. , -' "",,' · .....
~ -.' , """""""" .........
I 25 _ ~,~:.
, ..
.~ , .'
I --------= I 30
---
4 6 112.5 10.3 CL" Brown, mottled lightblue-gray-brown, moist,
5 8 102.5 22.8
6 6 103.5 19.9
7 , ~ 103. 2 18. 6
CL
stiff, silty, sandy clay
Yellow, mottled blue, green, gray, red-brown, ,
moist, very stiff, silty, sandy clay
··'cr.'::' Light brown, mottled yellow, moist, stiff to
SC dense, silty, sandy clay-clayey sand
ML NATURAL/TOPSOIL: Dark brown, moist, stiff silt
with orange chips, old rootlets
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GEOTECHNICAL BOIUr-.;G LOG I Date 10/6/80 Drill Hole No. B-2 Sheet 2 of 2
Project Name L & M La Costa Valley Unit No.5. Project No. 4800670-02 I Drilling Co. Morri son Dri 11 ing Type of Rig. __ .!::B.!::.u::::.ck~e:::...:t~A!.!:!.u..::s.g!::..er!--_______ _
Hole Diameter 2411 Drive Weight 2,300# to 25 I, 1 ,450# to 50 I Drop 12 in. I Elevation Top of Hole ±75 I Ref. or Datum MSL
GEOTECHNICAL DESCRIPTION
I 30-
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: -. -..... ~ ., . . -..
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8 20 109.5 13.9 SP
Logged By LV
Sampled By ____ ~L~V~ ___ ~ _______ __
Li ght gray, rno i st, . dense, rned i.urn fi ne sand
Total Depth: 31 Feet
No groundwater encountered
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LEIGHTON. flng ASSOCIATES 1
GEOTECHNICAL BORING LOG I Da te_--.:!:-l 0~/~6:L./~80:::..-___ _ Drill Hole No. B-3 ---=~---
I
Project Name L & M La .costa Valley Unit No.5 Project No. 4800670-02
Sheet 1 of 2 ------'--
~-------------~~-------------------~~~~=------Drilling Co. Morri"son Drill ing Type of Rig~_B_u.:..;:c_k_et~" ....;.A.:..;:u.:...lg....;.e~r ________ · ______ _
Hole Diameter 24" Drive Weight2,300# to 25', 1,450# to 50' Drop 12 in. ----'---I Elevation Top of Hole ±79' Ref. or Datum MSL
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SM
1 7 114.3 9.1
GEOTECHNICAL DESCRIPTION
Logged By LV
Sampied By LV ------~--------------
FILL: Medium gray-brown, moist, medium dense,
silty fine sand -
!'"
" . ' ... 2 8 103.2 16.9 SM Orange-brown, moist, very dense, slightly
clayey, silty, fine to medium sand ---:-;-::-.' ".-. ':---:--r" ' 5~~"~:'~,~,~,+----+-~~~~--~-----+---+--~-----------------------~--~--------~ ~ " "" ML-Gray-brown, mottled orange, moist, very dense,
-:' "'::', SM" slightly clayey, fine, sandy silt-silty sand
, ," '" 3 9 118.5 11.3"" -.~' . '.-.. '. '.
-.' '" .~: . . ,~. -'.' ,', . ",~ 10--f~:"",',-·.-.. ~. !---I--++---r----ll----+,S=M-:-_-f Medium brown, mottled blue, gray, orange, olive, -
ML moist, very dense, silty fine sand-fine sandy" --" ,,--., -.--
-
15-_-
--
---
4
5
7 111.8 14.1 silt
9 103.3 21.0
ML Medium brown, mottled blue, olive, gray, red,
moist, very stiff, fine,sandy,clayey silt
...
-
-
20~----~--~--~--+-----1-----+---+--~---------~---~--~----~--~--~ ML ~1edi urn brown, "mattl ed gray, moi st, hard,
----
-f---
------
25--
30
--. _ ..
-" ... :. ..
" . -'::' .' ' , . '., . '.
clayey silt
6 8 113.9 10.9 -
7 11 109.7 18.0
SP Yellow, moist, dense, fine to medium sand -"
LEIGHTON and ASSOCIATES
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GEOTECHNICAL BORING LOG
Drill Hole No. B-3 Sheet . 2 of 2 ----~~-------~--
I Project Name_,;;=L_&=--:..,M:.....;:;..La.:.-..,:C--=.o..:..s..:..ta::..-V...:..,a..:..11.:,..e..;::.y_Un_'_·t_N_O_. _5 ____ ----,-Project No. 4800670-02
Drilling Co. Morrison Drill ing Type of Rig~~B'-=u~c.:..:.ke=-t:......:...A:.:::u.:::!..g..:..er:..--____ -'-'-___ _
I Date_-1-0-1-6/-8-0----
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24" Drive Weight-",-1.z..,4.;,.":5;...:0",,,,#_t",,-o:::..-..:5;...:0~' _________ Drop 12 in. Hole Diameter
Elevation Top of Hole Ref. or Datum 'MSL
III
CJ II) ..c: ,...... • ..t ~ .f.l .f.l. ..c:bO :l p.1I) ~.s .f.l II) II) • .-4
Q e:.: J.4 .f.l Cl <
30
---
-
--~ -
35 --
~ ----"-' ~
~
::.:::: .. : ....
-... ::. ,ta.:.
.! .. !.: .. ' ... :-: " .. -,. ... '.
_ .. f., ,f. I. 'f • -:.:'".: .. '. : : .. " .' .-
40-l:-.,!: tk;: .... ~~"":':.' : . .... ... ·:::.t"::; ::
~
. >.
0 .f.l .f.l 1I).f.l .• ..t Z III 0 III ,...... J.4 s:: II) ~ 0 t::~ ::Sll),-..
.011) o Po. .11) 0 .f.l.f.JcM" ::s~ .-tJ.4 QP. 1IIs::'-' E-<~ I:QII) . '-' • .-4 0
~ >.. ~u
til .f.4 Q
8 10 113.9 10.9
.
III"""
III en cd • ~u u.
~tIl
• .-4 ::i ~'-'
GEOTECHNICAL DESCRIPTION
Logged By LV
Sampled By ___ .:::..LV.:..--_--------'''--
ML Medium brown, mottled blue, red and gray, moist,
hard, sl ight1y sandy, clctyey silt -
CL NATURAL: Red-brown, moist, very stiff, silty
clay, colluvium
SP Red-brown, moist, dense, medium to coarse sand with some gravel, old alluvium, cross-bedded,
channeled
~ .......,..,...
9 8 109.7 18.0 CL-Dark blue-gray-brown, moist, slightly stiff,
-+----=:;~~-+_~--I:----I-----l.~ p 1 ast i c cl ay .
-
-
45-
-
-
-
-
-
-
-
-
-'
.-
-
-
-
-
-
Total Depth: 42 Feet
No groundwater encountered
No caving
.l:.~IGHT~.~. art~ .• A-§SOCIATES
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GEOTECHNICAL BORING LOG
Date __ --~1Q~/~6~L~8~0--------Drill Hole No. 8-4 ----==--.:.-----Sheet'1 of 1 ----
Proj ect Name_--=L--.:&~M.!..-::L.::::.a.--:C=-=o:..:s:...:t:.:::a_V::..:a:..:l-.:.l~eYL....:.U:.:n:...:i-=t_N:.:.;o::..:.:........:.5 _______ Proj ect No. 4800670 ... 02
Drilling Co. Morrison Drill ing Type of Rig:...--.-:.B::..:u:.::c:..:..;k:.::e..::.t.-:.A.:.:u::..;;gL:::e~r ________ _
Hole Diameter 2411 Drive Weight 2,300# to 25', 1,450# to 50' Drop 12 in.
Elevation Top of Hole ±80 I Ref. or Datum MSL
o
GEOTECHNICAL DESCRIPTION
Logged By LV
Sampled By ___ -=L:..;.V ______ ..,.--
ML FILL: Light gray, damp, medium stiff, fine
--+-.:-,:-.. -.. -:-+----+--w--+--
2
---+--5-.......a.----sandy s i 1 t
_'.:.:':::,::' 1 5 11.8 1.9 SP NATURAL: Medi.um brown~ damp, dense, fine sand
.: ' '. ..
4 111.8 16.1 SC-Gray, mottled orange, moist, stiff, fi'ne clayey
-.:..,...:...:.. : CL sand-sandy clay
·~B: 5 ,': ':' ..... : H":"o-r'~' I-.-++--+----f--+-S-P+L-i-g-ht-g-r-ay-,-s-=-l-i g-h-t-:::'l-y-d-a-m-p-, -d-e-n-s-e-, -s-l-i g-h-t-l-y----+-I
-: .... .::'.: 3 7 08 9 3 6 silty, fine to medium sand, friable ... ' . 1. '. .. I' .". -" . ,. ,' .
• ,:. -;!I' •••••• : -,.~:' .. ' .. "
.. ': .. '" " , ' -.... "".,' '"."
" ,,' .~,,"
101-." "f, a.' It: ... " , ~: .... ' ,-,,: It" -,," . , . ,
:" :.:. '0·" . ,,' . ., -.......... .
-'0' ,,'.
, '. "" 4. " -~:" ., "::." ' :.:,," , .. ' ... :,
" .. :" , ..
<D.
4 7
-
\
SP Red-brown, damp, dense, medium to coarse sand,
some fine gravel; cross-bedded, friable -
-
-", .... :: .... . -',,, " .. .. .• ' 1-, ',." 15-1~~1---+--+1---r----1----~--+-------------------------~---------~ 6" to It Channel cuts in clay
---
-
---
5 6 107.8 21.5 CL-Pale olive-blue, moist, stiff, fat clay, massive
CH
·1 --
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20--=-
-. -'.---. . .
-'.-'-,-' . . . . ------'-. .
6 5 111.4 16.5 CL Pale olive ... blue, moist, stiff, medium, sandy
clay
25-;==~~·~'---+--+r~·b,,~--I----~~+---~--~~~~~----------------~~ ~' ,-0"" '" Total Depth: 25 Feet
-
-
-
-
30 .
No groundwater encountered
No caving
, _~EIGHT9N . ~fld I\~SOCIATES
-
GEOTECHNICAL BORll\G LOG II Date __ ~1_0..L..1"""7!.-/8_0,----_ Drill Ho 1 e No . __ "-B--.:-5=--___ Sheet 1 of 2
Pro j ect Name_~L=__=&~M......:L::..:a~ . .-..:C:..:.o-=-s..:.:ta=-.i:y~a:..:.l..:..l e::..y~. -=U~n...:..i.::..t ....:N-'-'"O=-=.~5_--'-__ -_1 Pro j cc t No. .4800670-02 II Drilling Co. "Merri~on ·DrN 1 i:ng Type of Rig' __ 2.Bu~c~k~et!:!...£Al!:!u!.:;j.g£er,-----_------
Hole Diameter 2.41,1 Drive Weight 2,,3QO# to .25\ .1,450}f to 50' Drop_~12",,----_in •
II Elevation Top of Hole +86 ' MSL Ref. or Datum
I
1 0 ...0.-' . .
II
II
I
I
II
II
II
II
II
II
II
II
II
-"-~--. . --. '''~'
I-
15-f---.
j-:; --;-' .. .;
-.:--::,:;:' .
-.
2n-:: ~u --:-:-.:* -_.' -.\ ...... -----'. ~ .. : ..
Ir -., 2;,r-...
.. ~ -
_..-....-':--":.: ...... : .... ;.: B' •
" . __ GOW
_ lOS
-II 30 ,-= I
15 4 10il 125.3 11.9
I I
GEOTECHNICAL DESCRIPTION
Logged By _____ L._V _______ _
Sampled By __ --:=.LV.!...----------
FILL: Light gray, damp, medium dense clayey to
silty fine sand ·Becomes dense to ver.y dense NATURAL: Pale yellow-gray, damp, very dense
fine to medium sand with some silt binder
gravel at contact .
ML-Violet mottled red-brown, damp, very hard clayey
SM silt with streaks of fine silty sand; massive
@ 27' red-brown silt layer 3" thick
~~IGHTQN9nQ. l~~SOCIA TES
...
-
-
I Date __ AI0!a/..4..7~/8~0!.--__ _ Sheet 2 of 2 --='---
Pro j ect Name_-=-L.-:&~M:.-=::..La=--C:...::o...:.s...:.t.:.:.a _V:...::a.:.....l...:.l..::.:ey=!.........:U:.:.n:..;;.i-=t-N:.:.;o=-:.:...-=5----~--Project No. 4800670-02
GEOTECHNICAL BORING LOG
Drill Hole No. 8-5 --.,.=:.--=------
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Drilling Co. Morrison Drill ing Type of Rig, __ -=B..=.u.::.ck:,:.:e::.,:t::.-;,..A:.=u.i2.9.::.er:--------
Hole Diameter 24" Drive Weight 1450# Drop 12 ---~~----------------
in.
+86' Elevation Top of Hole Ref. or Datum . MSL
. ~ ,n'-" II) 0 ~ ~ a>~ GEOTECHNICAL DESCRIPTION
0 a> Z 0 . -r! II) •
..c: ,-... .r! '"d a> II) 0 II) ,-.. J.t ~ CIS. tJ)
~ ~. ..c:bO ::3 ~p.. ~l.f.I ::3a>,-.. ~.
p.a> §<.3 ..." .0 a> 0 a> 0 ~ ~ o'@ u~ Logged By LV a> a> -r! ;j...-4 ...-4J.t Q P-II) ~'-'
Q t=.: J.t ~ £-4~ ala> '-' -r! 0 ...-4tJ)
t!) .~ ~ ·~u -r! ::) Sampled By LV
<: CIS c.. J.t tJ) Q g'-'
~ ML Olive-gray mottled red, brown, purple, moist
---nard, sandY. clayey silt
-5 39 120~2 . 15.3 --
........ 'O:: .. : hori:2 SM Medi urn .brown··, damp, very dense silty. very fine
-'O: •••• '.: ••• '. sand ,,'O .. '" ·oo • 'O.. ,
-:. ;: .:-... :-,:
~ .. ~ hOri2 35 .... ~ f'''' ML-., . Blue_ gray,_mois_t,_ very dense, silt -very fine .. :.: -: :'.: .. 50 -Sp
i\'\:: 6 10" 121.4 ·14.3 sand
: .. :,:: : ',: :: :':/:':".:
/ Total Depth: 39 Feet
40_ No groundwater encountered
No caving
]
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-
-
-
-
-
-.'
-
----
-
I I I II I -
kF'~IiTQN a'1p. A~SOCIATES
II Date 10/7/BO ------~~--~--
GEOTECHNICAL BORING LOG
Drill Hole No. B-6 -------Sheet 1 of '2 ------II Project Name L & M La costa Valley Unit No.5 Project No. 4800670-02
Drilling Co. Morrison Drill ing Type of Rig Bucket Auger ------~----------------~---
Hole Diameter 24" Dri ve Weight 2,300# to 25 1
, 1,450# to 50 1 Drop 12 in. II Elevation Top of Hole +B5 1 Ref. or Datum MSL
,II
II
II
.11
II
II
I
I
I
I
I
I
I
I
I
I
. >. ~..--III 0 .j.J .j.J Q).j.J GEOTECHNICAL DESCRIPTION :.
0 Q) 'M III •
,.c: ..--. 'M ] Z III 0 III ..--f..l s:: (ljCf.)
.j.J .j.J. ,.c:bll Q) ~ 0 s::~ ::3Q)..--~.
.oQ) p..Q) p,o .j.J ::;3~ o~ Q) 0 .j.J .j.J 0\° u~ Logged By. LV CI) CI) CIS....:l .,..j ~f..l OP, 1Ils::'--'
CI e:,. f..l +J E-<~ CQ Q) '-J 'M 0 ~Cf.)
t!) .j.J (Ij 0.. >. °u . 'M ::) Sampled By LV
<t: Cf.) f..l :::E t5$'-' 0
o ML-FILL,: Blue-gray, moist, stiff, silty clay' to
CL clayey silt CD 1 3 111.7 13.B
~==~--~~~~--~~--~~~--~~----------------------CL Olive-blue, moist, 1l1edium stiff, silty clay ---2 2 107.6 17.0 -----
5 .:: :<:';' ~ NATURAL: 1" thick, dark brown, moist, soft,
--r-:":'~ -' ... ..:.-.• ...:...: •. =+---!--I.J---I--~~--I. clay; old top so i 1
_ ..--3 2 113.7 15.1 ~ 1-~ Medium brown, moist, dense, fine sand
~ -'--CL. OJi"ve-gray, moist,.soft to medium stiff, silty
lO-j~ clay
Jr--==:
j:'~' 15~~ J,,~
.~
\ .;
-~". "'~ -"'---: .~ ., ...
-.,' "
" ·"0· 201-" --:7: , _ .. , ,
.~ , .. .!....--• l
-: ...... ~;-t
-:~
-0 -!-.
25~--.:.::':· , . '~ -. . . . -' -".:. '. . '''-'-;'':'' . . .
-~.' . '."
-~'. . ' ..... :
3n .
9 16 110.2 1B.4 CL Pale blue-green, moist, very stiff, slightly
silty clay; massive
+-----If----I ML-Pale violet mottled orange and red, moist, very
5 17 127.3 13.5
CL hard, s;·lty clay -clayey silt with streaks of
silty sand
SOCIATES
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Date 10/7/S0
GEOTECHNICAL BORING LOG
Drill Hole No._--=B:--;::..6----Sheet 2 of 2
---~~---------Project No._~4.::..;SO:...:0~6.:.....70.:.....-...;.0,;;:..2_--Project Name L & M La Costa Valley Unit No.5
Dri 11 ing Co. _....:.M:...:.:o=..,:r..,:.r..,:.i.=.s..::..o:.:,.n .....:D=..,:r.....:i:....:l..;,.l..;,.i :.:,.ng"'--_________ T.ype of Ri g, __ .=.B..::u.::.c:.:,.ke=-t::......:..A.:.::u~g.::.er.:.--____ ----
in. Drop 12 Hole Diameter 24" Drive Weight 1,450# to 50' ----------Elevation Top of Hole !a5' Ref. or Datum MSL
30 .:~"B:
--: ::, '" :: " E-W
~""2S , ;--r;-:'
I., : t • ...,. -;.
_ ; .I •• : ~.;,
~ to of: t. -0 ----.... -..:..!--: -:, ~" ":' -'
35 ,' ... " ., -~;~' . . ".:~' .. ~ ...... I
--------. 40--
SM
6 45 114.5 17.S SM
GEOTECHNICAL DESCRIPTION
Logged By LV
Sampled By LV
Dark red, damp, very dense; slightly silty fine
sand; massive
Medium brown, mottled gray and orange, moist
very hard, silty fjne sand; massive
ML-Dark blue-gray, moist, ve~y hard, silty. fine
SP sand; massive
Total Depth: 41 Feet
No groundwater ·encountered
No caving
.-
I Date Sheet 1 of 1 -=---10/]/BO
GEOTECHNICAL BORING LOG
Dri 11 Hole No ._--=8_-:..-7 ___ _ -----------------
I Project Name L & M La Costa V~lley Unit No.5 Project No. 4B00670-02
Drill ing Co. Morri son Dr; 11 i ng Type of Rig._--=B:.:::u..=.c:..:,:ke:::..;t::.....:..;A:;::u.;;z.ge=.;r:.-.-------------
in. Hole Diameter 1211 Drive Weight 2,300# to 25' Drop 12 I Elevation Top of Hole 'tao' Ref. or-=-Da~t:..:um:;:.::.~::...M--=;:5:.::.L---------..:.--
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I
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I
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I
II
I
-----
.~ .. . " .....
5 -.\:.: .. ::.:. .~ .. : ...... : .. :::
--
III G) -g
.f.J
"" .f.J ~
-hori~
-__ '8:
1 0'-1§::;:~ ... $ .... ~.'::' 50E
'lOS -----I--B: -EW -55
-
-----
20-.::::::::--=--------
--
. ~
0 +J +J G)+J ,,·rf '
G)z I/) 0 I/) r:-. J-I s:: ~ 0 s::tH ::SG)r" ,.oG) ou. 'G) U .f.J +J o~ ::Sr-:f MJ-I o'p.. 1/)s::\oJ f-o~ I:QG) • \oJ ·rf 0
t:l. ~ ~u
(/) .J-I 0
1 6 104,.3 22.6
2 9 104.7 1B.6
3 20 109.1 19.2
4 17
9"
5 27111.B 18.8
6 32 121.6 15.7
~r" III • as{/)
M' ul.!
M{/)
·rf ::i ~\oJ
CL
GEOTECHNICAL DESCRIPTION
Logged By 'LV
Sampled 8y ___ ....:L:.;V:---------
FILL: Medium brown mottled gray-brown moist
stiff clay to silty clay 1 to 2" diameter
rocks in upper 11 (10-15%)
CL-NATURAL: Gray-brown, moist, dense, fine sandy
5C clay to clayey sand ~ ,-
ML-Gray moist, hard, fine sandy silt to sandy clay
CL -
ML @ 10" 111 thi ck bed of 1 ami nated si 1 t
Dark red-brown, moist, hard, fine sandy silt
@ 13-15' medium sand beds 1-3" thick
ML Dark red brown-maroon, moist, hard, sandy clayey
silt; massive
-
25-+~~~-+--~-+----~--~·~,~--~--~~~------~------~----~ Total Depth: 25 Feet
-
-
-
-
30..
No groundwater encountered
No caving
L~IGHTON :a'l~ "SSOCIATES
I ' GEOTECHNICAL BORING LOG
" Date_-----.:1:.:0;.L.I..:....7/!...:8::.,:0=----Drill Hole No._..::.B_-.:...8 __ -~_ Sheet 1 of_I=--_
I Project Name ___ L_&_M_L_a_C_o~s_t-a_V_a_l_l_e-=-y_U_n_i_t_N_O_. _5 ______ Project No. 4800670-02
Drilling Co • __ ..;...M..;...o..:..rr:-i;....:s..;...o-n-Dr:-i-l-l..;...i.:..:.n9>!.------Type of Rig. __ ....:B:..:u:..:c:.:..:k..::.e.:...t ....:.A..;::u:..;;c9..::.e..:....r _________ --'-_
I
Hole Diameter 2411 Drive Weight 2,300# to 50' Drop 12 in. ~-------~-~~-------~--~
Elevation Top of Hole ±88' Ref. or Datum MSL
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". : .. : . N20W ;":~:10W
- : : ,;. .' ':~~ liori ~ ..... · . -' .. , · .-...... ,.-
~". -... ~
~ .... '
5-"~ '" ....... • .t .. :----;--...
--B:
- -N60E ~
--.-
1 0 ~~-----,,--*"-:~" .. : -: ..... * ..... ,
-~'" : ~ .. <; :::~ Hori ~
---
15---------------20--B:
25-
-
-
30 I
N7'OW
5S
1 13 104.8 19.4
2 20 118.5 13.9
3 17 109.8 19.7
10
4 f)1i 119.5 14
, I
GEOTECHNICAL DESCRIPTION
Logged BY ____ LV~------'--
Sampled By ____ L_V_~ _____ _
ML NATURAL: Gray moist, very stiff, very fine
sandy silt
ML-' Medium brown, mottled gray, moist, very stiff
SM hard, fine silty sand to sandy silt
ML Dark gray-brown mottled blue-gray and brown
fine sandy silt with gypsum
gypsum seam
SM Dark orange-brown, moist, very dense, slightly
clayey silty sand
ML Dark orange-brown hard fine sandy silt; massive
SP Dark gray moist very.dense silty medium sand;
cemented
Total Depth: 24 Feet
No groundwater encountered
No caving
!-.E1Gl1TQN anA .. ~~SOCIATES
GEOTECHNICAL BORING LOG
2 I Date 8/28/80 ----~~~--------
Drill Hole No. B-9 Sheet 1 of ----~~----------I Project Name ____ L_a __ Co_,s_t_a_v_a'_'_e_y_Un_l_·t_N_O_., _5 _________ -----Project No. 4800670 ... 02
Drilling Co. Anderson Drill ing Type of Rig Watson 60 Spin Auger
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Hole Diameter 36" Drive Weight_1...:.,:.-2_0_0#:..-__ -------------~--'-. Drop 12
Elevation Top of Hole ~31 Ref. or Datum MSL
GEOTECHNICAL DESCRIPTlON
Logged By SRH --~~~---------
Sampled By SRH ----------~----------
o SC FIll: Gray-green, stiff sandy day to clayey
--+---+---+--++--+---J-----'-r'........ sand, dry
-
-
-
5-
-
-
-
10-
-
-
-
15-
-
-
-
-
?6-
-
-
-
-
25-
20
1 12"
12
2 J2'f"
12
3 J2'f"
13
4 12"
SC FILL: Red-brown dense clayey fine sand, damp,
Fe oxide stains
SC FIll: Gray-brown, clayey silty sand, dense,
moist
SP FILL: Yellow-brown to gray-brown, silty fine
sand, dense, moist
.'
CL FIll:' li'ght brown, sandy sti'ff clay, damp
5 .. ' 'C1: FILL: Green-gray slightly sandy clay, stiff,
~ ____ -I-_-+--__ -.J---~-........... '-....... moist, lenses of orange-brown coarse sand
SC FILL: Yellow-brown, clayey sand, dense, damp. -Interbedded with gray sandstone -
in.
1-.
I -SP FILL: Gray-whlte, sl1ty, flne sand, dense, dry
3~
'. ,kEIG A~SOCIATES
1 Date ____ ~8~/~28~/~8~0 __ ~ __ _
GEOTECHNICAL BORING LOG
Drill Hole No ._~Br!...--,>!9------_ Sheet 2 of 2
1 Pro j ect Name __ L=.:a=--.:C:..:::o=-st..::.:a=--.:V:..::a~1..:.:1 e::.!y~U;..:n..:..i t=--.:.N:..:=.o...:..o_5::..-________ -,...-Project .. No. 4800670-02
Drilling Co. Anderson Drill i .. n....;g::..-_____ Type of Rig Watson 60 Spin AU'ger
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Hole Diameter ___ 3_6_" _______ Drive weight.~~ __ ~~ __________________ Drop----~---ino
Elevation Top of Hole
30 6 i~1I
J
-
Ref. or Datum
.,
GEOTECHNICAL DESCRIPTION
Logged By SRH
Sampled By SRH
SP FILL: Gray-white, silty fine sand, dense, dry
SP-FILL: Orange-brown, slightly clayey, ;coarse,
SC silty; sand, medium dense, damp
* ~----~--~~4+--~--~4-~'I---+--~~~~--~--~~--~----~~~~~~~----41 NATURAL: 'Gray to dark brown, soft, slightly
sandy clay, moist.
Grading into gray-brown:clayey dense sand
@ ~ 34' 35'
40~ SP . Orange-brown coarse sand, medium ·dense, cramp.
Rocks~ ~II to 111 in diameter.
1 . J
43 ~l ___ -+ ___ ~~~--~---~--+~~~~~--------------------H ~ Total Depth: 43 Feet II -j" No groundwater encountered
1
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-
-
-
-
-1 -
1
1
-
-
-
-
"
I~-~==~I'~==~~~~~~~~~~
LEIGHTON and' A~SOCIATES
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I APPENDIX B
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I ~aJ~
I LEIGHTON and ASSOCIATES
INCORPORATED
MAXIMUM DENSITY TEST RES
SOIL TYPE SOIL OPTIMUM MAXIMUM OR LOCATION DESCRIPTION MOISTURE(%) DRY DENSITY(PCF)
B-2 @ 81 Dark brown silty fine sand 12.0 124.0
B-2 @ 15 1 Brown mottled blue silty, sandy 12.5 118.5 clay
B-6 @ 11 Slue-gray silty clay/clayey silt 12.5 121.0
EXPANSION INDEX TEST RESULTS
SAMPLE INITIAL COMPACTED DRY FINAL VOLUMETRIC EXPANSION EXPANSIVE
LOCATION MOl STURE (%) DENSITY (PC F) MOISTURE(%) SWELL(%) INDEX -~.-CLASSIFIGATION
B-1 @ 21 6.7 107.5 20.3
.. -Low to
4.4 44 Moderate.
B-2 @ 8 1 4.4 107.0 18.4 1.7 17 Low
8-6 @ 11 11.1 100.7 26.3 5.8 58 r40derate
Project No: 4800670-02 Leighton & Associates Plate No: 8-1
o-J ,
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I .
300 0 . I
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2~0 0 . ,
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2000 I
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1
1500
, ,
I ,
1000
I
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Boring Depth
8. .. 2 6 {:_7l
8 ... 3 3l -41.
Project NO,I 4800670-02 .
3 4 04,a,n)
DIRECT SHEAR SUMMARY
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1000 1500
NORMAL STRESS. PSF
Symbol Friction
Anoli
8 3QO
e 28°
Leigh.1pn & A~~f>C.!ates
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2000 21)00 3000
Cohesion Remarks
200 psf"
400 spf
Plate No.1 8-2
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0.05
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CONSOLIDATION -PRESSURE CURVE
PRESSURE (Kips per Square Foot)
0.1 0.5 1.0 5.0 10.0
0.1 0.5 1.0 5.0 10.0
o Indicates Sample .Indicates Sample
After Saturation
50.0
50.0
I At Field Moisture
L--. ______ ----.----------'
Plate No.: B-3 Project No.: 4800670-02
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I APPENDIX C
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I [1]M
I LEIGHTON and ASSOCIATES
INCORPORATED
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GENERAL GRADING AND EARTHWORK SPECIFICATIONS
1. Scope
al This section contains general spec{fications for work relating to the
fo 11 owi ng constructi on.:
Site Clearing and Gr.ubbing
Preparation of Subgrade in Areas to be Filled
Placement of Fill
Subdrains
Trench Backfill
b} The owner shall employ a qualified soil engineer to inspect and test
. the fill as placed to verify the uniformity of compaction to the ~pec
ified density requirement. The soil engineer shall advise the owner
-and, grading contractor immediately if any unsatisfactory soil related
conditions exist and shall have the authority to reject the compacted
fill ground until such time as corrective measures necessary are taken
to comply with the specifications. It shall be the sole responsibility
of the grading contractor to achieve the specified degree of compaction.
2~ Clearing, Grubbing and Preparing Areas to be Filled
a) All brush, vegetation, rubbish and desiccated top clay soil shall be
removed, piled, or otherwise disposed of so as to leave the areas to
be filled free of vegetation, debris and desiccated top clay soil.
Any soft and swampy spots in the canyon areas shall be corrected by
draining or by removal of the unsuitable materials.
b) The nat~ral ground which is determined to be satisfactory for the sup-
port of the filled ground shall then be plowed or scarified to a dePth
of at least six inches (6") and until the surface is free from ruts,
hummocks, or other uneven features which would tend to prevent uniform
compaction by the equipment to be used. The scarified ground should
be compacted to at least 90 percent of-the maximum laboratory density.
Where undisturbed bedrock is exposed at the surface, scarification and
recompaction may not be required.
c) Where fills are made on hillsides or exposed slope areas, the existing
top unstable materials should be removed. If existing slopes are
steeper than 5 horizontal to 1 vertical, horizontal benches shall be
cut into firm and competent undisturbed soil or bedrock in order to
provide both lateral and vertical stability. (See benching detail
page VIII of this Appendix.)
d} All areas to receive controlled fill, ;-nc1uding all removal areas and
toe-of-fi11 benches, shall be inspected and approved by the soil
engineer and/or engineering geologist prior to placing controlled com-
pacted fill. ..
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3. Fill Materials and Special Requirements
The fill soils shall consist of select materials approved by the project
soil engineer or his representative. These materials may be obtained
from the excavation areas and any other approved sources and by blending
soils from one or more sources. The material used shall be free from
organic vegetable matter and other deleterious substances, and shall not
contain rocks or lumps of greater than eight inches in diameter within a
distance of ten feet from any finished compacted surface. If excessive
vegetation, rocks, or soil with inadequate strength or other unacceptable
physi ca 1 characteri sti cs are encountered, these shall be di sposed of •.
During grading operation, if potential problem soils are found, these
soils shall be tested to determine their physical characteristics. Any
special treatment recommended shall become an addendum to these specifica-
tions. Boulders greater than eight inches but less than or equal to two
feet in diameter should be uniformly distributed in the compacted fill
areas but no closer than ten feet from final grade and should be sur-
rounded with sufficient amounts of compacted finer-grained materials. No
nesting will be permitted. Boulders greater than two feet in diameter
shall be placed in approved disposal areas no closer than ten feet from
final grade and shall be placed in windrows in such a manner that voids
will not exist around boulders. (See rock disposal detail, page ix of
this Appendix.) Continuous inspection by ,the project soil engineer is
required during rock disposal operations.
4. Placing, Spreading and Compacting Fill Materials
a) The suitable fill material shall be placed in approximately level
layers which, when compacted, shall not exceed six inches. Each
layer shall be spread evenly and shall be thoroughly mixed during the
spreading to insure uniformity of material and moisture in each layer.
b) When.the moisture content of the fill material is below that specified
by the soil engineer, water shall be added until the moisture content
is near optimum as specified by the soil engineer to assure thorough
bonding during the compacting process.
c) When the moisture content of the fill material is above that speci~'
fied by the soil engineer, the fill material shall be aerated by
blending and scarifying or other satisfactory methods until the mois-
ture content is near optimum as specified by the soil engineer.
d) After each layer has been placed, mixed, and spread evenly, it shall
be thoroughly compacted to not less than 90 percent of maximum density
in accordance with ASTM D1557-70 (five layers). Compaction shall be
accomplished with sheepsfoot rollers, multiple wheel pneumatic-tired
rollers or other approved types of compaction equipment. Rollers
shall-be of such design that they will be able to ,compact the fill
material to the specified density.
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5.
e) Special mixing and watering effort may be required where diatomaceous
materials are encountered to achieve the recommended moisture content
and density.
f) Fill slopes shall be compacted by means of sheepsfoot rollers or
other suitable equipment. Compacting of the slopes shall be accom-
plished by backrolling the slopes in increments of three to five feet
in elevation gain qr by other methods producing satisfactory results.
Relative compaction shall be at least 90 percent to the finished ~
slope face.
g) The soil engineer and/or his designated representative shall observe
the placement of fill and shall take sufficient tests to provide an
opinion on the uniformity and degree of compaction bei.ng obtained.
Subdrains
a) All materials used in the construction of the subdrain systems shall
be of the required types and sizes shown on the drawings or approved
by the soil engineer. Canyon subdrains shall be constructed as shown
on the attached drawing, Canyon Subdrain Construction (page vii of
this Appendix). '
b) All drain lines shall be installed to conform to the grades and align-
ment shown on the drawing. Modifica~ions of the subdrain layout as
may be required in the field must be approved by the soil engineer and
civil engineer.
c) The subdrain pipe (perforated and nort-perforated) shall be approved
by the soil engineer. If the diameter pipe called for on the drawing
is not available in the material chosen by the contractor, the next
size larger pipe available shall be used in its place at no additional
cost to the owner.
d) Prior to backfilling, the locations of all drains shall be surveyed
by the civil engineer. It is imperative that the subdrain outlets
be kept clear during grading to avoid damage to the exposed pipe.
e) The fill operation shall be continued to six-inch compacted layers,
as specified above, until the fill has been brought to the finished
slopes and grades as shown on the accepted plan.
6. Trench Backfills
a) Trench excavations for utility pipes shall be backfilled under engi-
neering supervision.
b) After the utility pipe has been lain, the space under and around the
pipe shall be backfilled with clean sand or approved granular soil
to a depth 9f at least g~~ foot over the top of the pipe. The sand
backfill shall be uniformly jetted into place before the controlled
backfill is' placed over the sand.
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c) The on-site materials, or other soils approved by the soil engineer,
shall be watered and mixed as necessary prior to placement in lifts
over the sand backfill.
d) The controlled backfill shall be compacted to at least 90 percent of
the maximum laboratory density as determined by the ASTM compaction
method described above.
e) Field density tests and inspection of the backfill procedures shall
be made by the soil engineer during backfilling to see that proper
moisture content and uniform compaction is being maintained. The
contractor shall provide test holes and exploratory pits as required
by the soil engineer to enable sampling and testing.
7. Geologic Inspections
a) Graded slopes are to be periodically inspected by the engineering
geologi.st to provide an opinion on the stability of excavated slopes.
b) Inspection of excavations other than cut slopes may be required to
refine geologic parameters related to fault hazards, landslide
hazards, or other geotechnical hazards that may be indicated.
c) Surcharged cuts are to be inspected by the engineering geologist prior
to placement of the surcharge fill prism.
d) Canyon c1eanouts will be inspected by the engineering geologist prior
to subdrain placement or placement of fill •.
e} Buttress keys Will be inspected by the engineering geologist prior to
placement of the buttress fill.
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nop J CAL HIlTfRESS SECT J O~\S
Gener:!.l Buttress Fill Section
4U diameter outlet pipes at 100'
horizontal intervals
f
20' max. typo
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l' Clr
b = 1 max
30" compacted
fill blanket as
needed
Subdrain -See "Buttress
Subdrain Detail"
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I 1~ I D and W DETERl\IINED ,BY DESIGl\
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Small Buttress Section
'--15'1
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4" diameter outlet pipe at 100'
horizontal intervals
H = 20 ft. max
l' c1T
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30" compacted fi 11
blanket as needed
Subdrain -See "Buttress Subdrain Detail"
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J\ .... __ #. L-,<" \.J' \ I ....... ,,, .. ...,
411 min. diam. solid outlet
pipe spaced at 100' hori:;:ontal
intervals.
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A
Gradient
A
compa c t e,d
fi 11
J.I in". " 3 f t 3 per 1 in. f /
Filter Haterial / ...
Tilin. approved
perforated pipe
( per for 3 t ion 5 d 0 \; n )
minimum 2% £rzcient
to outlet.
Bench inclined toward
drain
Typical benching
T~mporary fill level
METHOD B t.fETHOD A
~{i n.
12"
cover ----~
compacted backfill
~r~'(::.: 6" ~ti n. s e 1 e c t bedding
~" . backfill
Ii 2" ~~i ~J T IL lHn. 4" clinm. approved
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solid outl~t pipe
DETAIL A-A
Filter matcrizl to meet follo~ing
·specification or approved equal:
Sieve Size Percentage Passing
1·' ............... 100
3/4" ••••••..••••• 90-100
3/8" ••••••••••••• 140-100
No.4 ••...•••.•.•• 25-40
No.8 •..••.••••••• 18-33
No.30 •••••••••••• 5-1 5
No.50 •••••••••••• 0-7
NG.200 ••••••.••.• 0-3
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Approved Pjpe Ty~)e$:
1. Schedul~ <10 Poly-Vinyl-
Chloride
2. CorrugatC'd ~lctal Pipe l-tg:l.
6" AC dipped
3. Al"ur.linum Corl"llj:!:ltcd Pipe
1000 psi AC <11 pped
4. Acrylonitrile }\lltacJincnne Styrene
Schedule .10, 900 psi
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CANYON SU SDRA IN DETA II.S
-----
Compacted
Fill
Surface of firm
-;:-earth material
//
Typical benching
1/1
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Remove unsuitable
material
'-__ ../ J..--.J
'-/ Incline toward drain
See detail below
1-1ethod A -------,-----.~
..---Hin. 9ft 3 peT 1 in. ft.
of approved filter
material ,.
'.., T , .. ~ . . ..
't • • . ~ , • ,
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Min. 4" diara. approve,d
perforated pipe
(perforations down)
Nethod B
:: :'.' : . '.' 6" S e 1 c c t g r a nu 1 arb c d din g
14" I T compacted to 90~ r.lLlX. dens. I" 1>1 in.
Min.
DETAIL
Filter material to meet following
specification or approved equal:
Sieve Size Percenta~e Passing
No.50 ..••••.••••• 0 -7
No.200 ••••••••• r.O-3
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~pproved Pipe Types:
1. Schedule 40 Poly-Vinyl-
Chloride
2. Corru!!3ted ~\ctal Pipe 14ga.
6"AC dipped
3. Aluminum Corrug:lted ripe
1000 psi AC dipped
4. Acrylonitrile But:1diennc
Styrene Schedule 40, 900p~i
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I BENCHING DETAIL
TOE OF SLOPE ~ SHOWN ON GRADING PLAN lOP OF FlL L SLOPE
VARIABLE FILL
'ILOPE HEIGHT.
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PROJ ECTED._
1:1 MIN.
NATU RAL
SLOPE
---
..--..--..-..... ..-
..-.-~\.. -
-.,.---.... -, --
_ .,.. '\ ~J~ \ r __.... --4' T Y P.
_ -c \.1.P--.... -B NCH _ "\ '"' 'O\.. \. .-.---I.~ E .... -" U~c:,U\ ,......=:. __ -_-_. _________ --I~EIGHT
_ ,-~_t.\.1. ..... 0-Nt." ,.. .... ~, '/ , ,J . (VAR I E~ rl-I------J 5 ~ TY P. -1
BENe H· WI DTH
viii
LEIGHTON and ASSOCIAT£S
INCORPORATI:D
BUILDl NG
FINISH GRADE
ROCK DISPOSAL DeTAil
(BOULDERS GREATER THAN TWO
FEET IN DIAMETER)
CLEAR AREA FOR FOUNDATIONS.
/UTllITIES1AND POOLS'
0-:-0 0-0
o O~
4'
f
~
o J ~ LIS' "-.
"" WINDROW
r ""--,-
TYPICAL WINDROW DETAIL {EDGE VIE~
,------HORIZ. PLACED
JO~ OR BELOW DEPTH
OF DEEPEST UTIUTY
T RENCH WHICH EVER D.EEPf
CLEAN (S.E > 30)·
. G RANULAR SOil
fLOODED TO FILL
VOl DS
\------CO~ PA CTE D FJ L L --'----,----_+_~
~----------------IS' --~--~------~
PROFIL E VI EY.'
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TRANSITION. LOTS
CUT LOT
Original Ground
--_I-
-----en _--. or ere r -. ~ ..,.... ---_ eo\\u'J\U"" .---1opsO\\ t _----
-"....
"....---Overexcavate and recomp.oct
Unweathered bedrock or material
approved by soil engineer
CUT -FILL LOT
----.-'-~ ..,....-----
Ground
-"....-Co m p oci e d fi·1I __ - -C'( e e t> _ ~ __ ----Il-L'--L-L+L--L.,.....L...,....'--'
_--ot ",--. -. {{\' -_ - -~ \\l~\\l . .,c::..-------~ Overexcovafe and recompact _\ CO _
nSo\' .--,Or _-• --Unweafhered bedrock or material
approved by 50il engineer
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