HomeMy WebLinkAboutCT 01-09; LA COSTA TOWN SQUARE COMMERCIAL; GRADING & HYDRAULIC REVIEW; 1991-07-10Geotechriical 'Geologic. Environmental
5741 Palmer Way. 's Carlsbad, California 92008) • (760) 438-3155 • FAX (760) 931-0915
/ .. July 10, 1991.
W.O. '1047-SD
RICK ENGINEERING COMPANY
1959 Palomar Oaks Way, ,
Suite '200
Carlsbad, California' 92009
Attention: Mr. Ray Martin
Subject,: ' Review of Grading and, Hydraulic Structures for'
,Desilting Basins,. La Costa Twn Center
Gent1inen:
As. requested by Rick EngIneering Company,. GeoSoils, Inc. has
'reviewed the I11=40' "scale grading plans for: the La Costa Town
Center.
The purpose of this review was to evaluate the grading and hydraulic
structures for proposed detention/desilting basins. This review is
based on updated mass grading plans for La Costa Town Center,
prepared by 'Rick Engineering Company.
Review of, the mass grading plans indicate that basins will be
Constructed in.close proximity to fill slopes. It. is our.
understanding that 'these basins are permanent structures. We
recommend therefore, 'that the deténtion/1esiltation basins be, lined
with either concrete or other 'low perine4ble material to hinder the
migration of water in the subsurface.
Review of the desilting' basin riser & deiatering detail, located on
Sheet 2: of' the mass grading plans, shows one inch (111) aggregate
placed 'adjacent to the riser and anchor block. In order to mitigate
the potential for piping. around the 'anchr block and outlet pipe it
'is recommended that a two , foot minimum 1width of compacted fill be
RECEIVE
OCT 12
RICK • ENGINEERING COMPANY
. . (
JULY 10, '1991
W.O. 1047-SD
'.
,' ' PAGE 2
placed between the basin. 'riser and aggregate .' (Figure :1).
Alternately, a concrete cut off wall, extending at least 12 inches
beyond the limits of the aggregate could' b used.
During the life ,of the desilting basin, 'it" .can be 'anticipated that
successive rainfall events will, result in'iltation of the aggregate
material. This might ultimately clog the aggregate surrounding the
perforated drainpipe. We
,
recommend thatl a maintenance program be
established to ensure proper . function of' tie basin.
If you have any questions regarding this Ireview or if we can be of.,
'further service, please, do' not hesitate t' contact this' office.
Very truly yours,
Geosoils, Inc. '
Robert G. Crisman ., Vitia Singhaet, GE 782
'Staff Geologist . •Geoltechnica1 Engineer
cc: Addressee SIN
M.A.G. Properties, Mr-. Fred
Z3 782 Rick Engineering*, Mr. D
Rick Engineering,- Mr. enn
is CC Up. 12-31-93
OFG
i'.
GoSoils. Inc.
ANCHOR
BLOCK
COMPACTED'
OUTLET -
PIPE - S
not to scale
FIGURE 1
rSCHEMATIC DRAIN DETAIL
GeoSols,Inç. DATE 7/911 rc IWO. NO 1047 SD
1 BY
Soil Mechanics • Geology *'Foundation Engineering
-----
Geotechnical -'Geologic • Environmental
5741 Palmer Way •, Carlsbad, California 920081 • (760) 438-3155 • FAX (760) 931-0915
RECEIVED
OCT02 199?
LAUWIO D[SIIili OR
/ ..May 16, .1991
W.O, 1047-SD
M.A.G PROPERTIES
7690 El Camino Real, Suite 209
Car'Isbad,:Californla 92009
Attention: Mr. Fred MoreyH
Subject: Discussion of Plan Check Notes .
La Costa Town Center
Dear Mr. Morey:.. .
As requested, GeoSoils, Inc. has preparec this report. in response to
plan check notes provided by the' City of Carlsbad' Engineering
Department. ,' These notes are, the result of a plan check' of the
111=40' scale mass grading plans for, the Ia Costa Town Center.
The purpose of this report is to respond to and, provide:details
pertinent to these 'plan check. notes,on the mass grading plans for
the La Costa Town center, prepared by Rick Engineering Company.
It is our understanding t1iat the'primary areas of concern with
regard to the plan check. are'':-,
1) 'Undercutting of 'transition lots and lots where blasting is
required. .
Details on perimeter fill slope keys.
Subdraihs and their points of discharge.
Anticipated remedial grading.
M.A.G. PROPERTIES .. MAY 16, 1991
W.O. 1047-SD PAGE 2
The above indicated concerns 'will be adrëssed in the following
discussions in the order as they appear aove.
Lot Undercuttin
It is our 'recommendations that undercutting of pads should not
necessarily be performed 'during' theL mass, grading phase of
development unless ultimate design plans showing: building locations,
foundations, utility locations and 'deptIs etc. are available for
review. Specific recommendations would b6 provided once these plans
are made available. . .
It is anticipated that the. recommenced overexcavation depths
described below should, be sufficient forl the proposed development,
'however, these recommendations are subje'ct to modification'by this.
office based on a review of ultimate projct design.
For lot undercutting or capping of transilion lots it is, recommended,
that the cut, and portions:of the- f.i4 area be overexcavated a
minimum of five feet and brought to grad4, with compacted fill, this,
is to "provide a uniform 'bearing materi:al .and greater 'insulation
against the contrasting properties ,of tr;nsition materials involved
(i.e. expansion and: seismic 'acceleratior)'. , Rock _fills should be I -
capped with a minimum five foot thick soil fill
Pad areas where blasting "is anticipted should be undercut
approximately 5 feet and, brought to grade ]with compacted fill. This
should be accomplished in order to provide an adequate. fill
thickness below footings, facilitate excavation for foundations and
trenching for utilities.
Foundations for any structur'should be 6ntirely in uniform bedrock
or compacted fill. Placing highly should be avoided
in the upper five () feet, of the building pads, if possible.
GeoSoils, Inc..
M.A.G. PROPERTIES
. . " . . 1M 16., 1991. W.O. 1047-SD
;. . ..
Slope Benching
Side-hill fills should have
a
n
.
e
u
j
p
m
n
t
-
w
i
d
t
h
k
r
a
t
t
h
e
i
r
t
o
e
'
excavated'through all surficj
a
'
l
s
o
i
l
a
n
i
n
t
o
c
o
m
p
e
t
e
n
t
m
a
t
e
r
i
a
l
a
n
d
tilted back in the hill (GS-1, GS-2 and GS-
5
)
.
A
s
t
h
e
f
i
l
l
i
s
elevated, it should be be
n
c
h
e
d
t
h
r
o
g
h
s
u
r
f
i
c
i
a
l
s
o
i
l
and slopewash, and into competent
b
e
d
r
o
c
k
.
.
o
r
'
o
t
h
e
r
'
m
a
t
e
r
i
a
l
d
e
e
m
e
d
suitable by the Soil Engineer.
'
Perimeter Fill Slope Keys
, Keys for perimeter fill 'slope
s
a
l
o
n
g
L
a
C
s
t
a
A
v
e
n
u
e
,
w
i
l
l
r
e
q
u
i
r
e
a
key roughly .25 feet wide.and.
7
f
e
e
t
i
n
d
e
p
t
h
f
o
r
s
l
o
p
e
h
e
.
i
g
h
t
s
o
v
e
r
.
20 feet. Perimeter slop 'keys, e9os
i
n
g
v
o
l
c
a
n
i
c
r
o
c
k
' are anticipated to be 15(±) feet'w
i
d
e
a
n
d
a
m
inimum' of 3 feet into dense bedrock. Perimeter slope keys f
o
r
f
i
i
i
'
. s]opes on Sheets 6 and 9 are
anticipated to expose vóT'c
a
n
i
c
r
o
c
k
.
T
y
p
i
c
a
l
- stabilization type backdrains would be recommende
d
f
o
r
a
l
l
p
r
i
m
e
t
e
r
f
i
l
l
s
l
o
e
k
e
y
s
.
Subdrains
Subdrain locations are indica
t
e
d
o
n
t
h
e
1
4
4
0
'
'
a
s
-
b
u
i
l
t
m
a
s
s
g
r
a
d
i
n
g
plans prepared by Rick Engi
n
e
e
r
i
n
g
.
S
u
b
r
a
i
n
s
a
r
e
o
u
t
l
e
t
t
e
d
i
n
t
o
storm 'drain' inlets, assuming '
t
h
e
C
i
t
y
'
o
.i Carlsbad will not allow drains to outlet onto theH'str
e
e
t
s
u
r
f
a
d
e
s
.
S
u
b
d
r
a
i
n
s
s
h
o
u
l
d
c
o
n
f
o
r
m
to schematic diagrams GS-1,-"G
S
-
-
3
a
n
d
:
G
S
-
4
,
a
p
p
r
o
v
e
d
b
y
t
h
e
s
o
i
l
s
engineer.
Reinedial'Grading
Buttress Slopes.-
.
Generally the sedimentary bedr
o
c
k
u
n
i
t
s
e
x
h
i
b
i
t
g
e
n
t
l
e
(
2
t
o
,
5
(
±
)
'degree) dips to the west
a
n
d
s
o
u
t
h
w
e
s
t
e
r
l
y
f
a
c
i
n
4
c
u
t
s
l
o
p
e
s
exposing sedimentary rock is
a
n
t
i
c
i
p
a
t
e
d
.
!,Specifically, the' slopes on Sheets 3 and 4 of the gra
d
i
n
g
p
l
a
n
s
a
i
j
e
a
n
t
i
c
i
p
a
t
e
d
t
o
r
e
q
u
i
r
e
stabilization due to adver
s
e
"
b
e
d
d
i
n
g
p
i
n
e
s
a
n
d
e
x
p
o
s
u
r
e
o
f
a
sandstone/claystone contact.
.
N.A.G. PROPERTIES
W.O. 1047-SD MAY 16, 1991
PAGE 4
Cut slopes exposing. the contact between'sedimentary,'and volcanic
bedrock may also require stabilization. The slope descending from
the proposed alignment of Rancho Santa Fje Road (Sheets 7 and 8)' is
anticipated to require 'stabilization. Te cut portion of the slope
on Sheet 6 is anticipated 'to' require stabilization as álaystone
bedrock may be exposed froni Stations 51± to. 155±. Typically,
stabilization fills should be a consisterk width of at least 15 feet
frop top to bottom. Stabilization fills should be' provided with
backdrainage as' presented in the referenced report.
Cut slopes exposing volcanic bedrock are not anticipated to' require.
buttressing or stab ilizàtión, unless continuous fractures or shears
are encountered. Also, overblastingcan'weaken the rock, material,
necessitating stabilization. :
All cut slopes" should be mapped by a 'eo1ogist from this office
during grading to allow for. amendments to recommendations,. 'should
exposed conditions.' alteration of the design on
'stabilization.
If you have any questions concerning this report, please do not
hesitate to contact' this office.
Very truly vour
GeoSojIs, Inc.
Robert G. Crisman Vitha Sin anet,. GE 782
Staff Geologist Geojechnical Engineer'
ei 0 Me alfe, 11.4 2
Principal Geologist
RGC/VS/TEM/ni 782
cc EXP. 12-31-93
Enclosures: Reference List
Plates GS-1 through GS-5,
GeoSoils, Inc.
REFERENCES
GeoSoils, Inc., December I7,:.'19901 Reviewj of 111 =40' Scale Grading
Plans La Costa •Town Center j ::La Costa. Ai.enue and Rancho Santa Fe
Road, Carlsbad, California,
GeoSoils, Inc., December 13, 1990, AntiOiaed.Subdrain Locations, La
Costa Town' center, Carlsbad, California,, ip. enc.
GeoSoils, Inc., June 2, 1990, Preliminary c.eotechnical Study Update,'
Parcels S.E. 13,' and. 25 Acres Easterly of La Costa' 'Avenue and
Mission Estancia, La Costa, City of,Car1s1ad, California, 28pp.
GeoSoils, Inc., 1982, preliminary Geologic and Soils Engineering
Investigation, parcels S.E. 13 and 14 in La Costa, City of' Carlsbad,
California.
/
Final Grade
Original ground
Loose Surfdce' Deposits
Suitable Suitable
Material -' 4 -.1;- - b Material
Bench where slof/"
exceeds 5:/ \ Subdrain
(See Plate GS 3)
TYPICAL TREATMENT OF
NATURAL GROUND
GeoSols; Inc. DATE 9.Z91. WO NO 1047—gnBY
Soil Mechanics ° Geology • Foundation Engineering
TOE SHOWN ON
0
IZGRADING PLAN. . . I .
---
0• . . .___-.1•• .
I
000 — I . I. Tv ni t n PROJECTED ,o
10 10' Typica I NATURAL
SLOPE
'loll
,f.
I-.-
_____
%(
2'I'I'"
Minimum 15' Minimum
BEDROCK- OR FIRM
FORMATION MATERIAL
Note : Where natural slope grad ilent is 5:1 or less,
benching is not necessary unless stripping
did not remove all compressible material..
TYPICAL FILL OVER NATURAL. SLOPE
GeoSols;Zne. DATE 5/91 WO NO 1047-SDI BY GSI
Soil Mechanics • Geology • Foundation Engineering
.---- - -.-.— .-
ALTERNATE 1
SOIL- SLOPEWASH
-1z 0 ALLUVIUM REMOVED
TO BEDROCK
\ /••'
BEDROCK
Canyonsubdrain.: 6"
S
pierforated pipe with
9 cu. ft. gravel per ft.
of drain wraped with
filter fabric.
I ALTERNATE 2
6` perforated pipe with
3 9 cu. ft. gravel per ft.
of drain wraped with
filter fabric.
5' CANYON SUBDRAIN DESIGN
AND CONSTRUCTION
GeoSofls, Inc. DATE 9491 1 W.0.NO 1047-SD(BY
S Soil Mechanics • Geology • Foundation Engineering
1
'36 I THICK FILL CAP
2%..,.
SURFACE . ' •. . '.
. . .
0 • •
0 •' .
SUR'''..
ROU t4
: . ': .' !
COMPACTED • . 7' - : •'FILL '
'D. (See drain detail).\
'0 0 -.-.---
0 • .
f l '•/ - . S
F '
c'•
"S
TYPICAL' BUTTRESS SECTION
GeoSoils, Inc. DATE 91/i (W.O.NO. 1047-SDIBY GSI
Soil Mechanics 9 Geology • Foundation Engineering
FINISHED
Buttress slope to have a bench
at every 20 to 30 feet...
Buttress key depth varies'. (see
preliminary reports)
Q . Buttress key width varies. (see
preliminary reports)
D. Backdrains and lateral drains
located at elevation 'of every
bench drain. First drain 'at
elevation just above lower lot
grade. Additional' drains may
.be'. required 'at discre'ti'on of
GeoSoils, Inc. '
4"perforated pipe ,
(or approved equivalent)
placed in I Cu. ft. per
linear ft. of', graded .'
filter material.
Pipe to ext
*Pi
full length
buttress;-
4nonperforote
piip'e lateral to
s[ope face at • J-Thbove,.._-
100' intervals J'bench
I,
"Graded filter, material to
'conform,to State. of Calif.
Dept.. Public Works standard
specifications for Clas.s 2
permeable material
FlLL1SLOEE..
11
"—CLEAR ZONE
S
'-EQUlPMENT WIDTH-)
r O3 0O000°Q
Soil shall be pushed
over rocks and flooded
into voids. Compact
around and over' each
windrow. S
Stack boulders end to end.
Do 'not pile upon each other.
N,FlLL SLOPE
C.) .0° •.O
'(Stagger rows N
o 0 . o o ,
'N 15'
3'minimum 'Ninimum
7>i15'MIj
- I
'• N, / / \ / - '
FIRM GROUND /. / N
ROCK DISPOSAL DETAIL
GèoSoils; Inc. DATE igi W.O. NO 1047-SD IBY GST
:1 ;
,°.-,,,• r' Soil Mechanics • Geology ° Foundation Engineering.