TECHNICAL PROVISIONS WEST VISTA WAY SEWER - PHASE 1 C.I.P. No. 8077

bulgefetaUrban and Civil

Nov 29, 2013 (3 years and 9 months ago)

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City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


165

TECHNICAL PROVISIONS


WEST VISTA WAY SEWER
-

PHASE 1

C.I.P. No.
807
7



Replace Section
30
6
-
8 MICROTUNNELING

with
the fo
llowing

new part:


PART
7

-

MICROTUNNEL CONSTRUCTION



SECTION
7
00


MICROTUNNELING

(STEEL CASING)


7
00
-
1

GENERAL
.

7
00
-
1.1

Scope
.


The
Contractor shall perform all Work to provide buried piping, specials and appurtenances shown,
specified and required for the construction of complete and operable pipelines using the
microtunneling method of installation.


The Work of this Section shall in
clude the construction of sanitary sewer pipelines by a typical pipe
jacking method using a
specific
remote controlled tunneling operation
named microtunneling
to
install the pipeline to the alignments and grades shown on the Drawings. Remote controlled
t
unneling operations shall apply to the trenchless pipe installation method of microtunneling or
remote controlled pipe jacking where the carrier
or casing
pipe is typically installed directly behind
the microtunneling boring machine (MTBM) and where the

MT
BM provides support to the
face at all
times.


This Specification is intended to define in general terms

in which

the Work
is
to be accomplished.
The Contractor shall have sole responsibility for the means and methods utilized to install the sewer
pipelin
e to the lines and grades shown and for preventing settlement or heave, all within the
tolerances specified herein and subject to review by the Agency. In such case, the Contractor shall
demonstrate to the Agency that the proposed means and methods shall
complete the Work in
accordance with the Specifications, this
Part 7
, Applicable Codes, and the Construction Schedule.


The Contractor shall provide all items required to complete the Work by microtunneling including,
but not limited to, the microtunneling
/jacking system, spoil transportation and separation, hoisting,
lifting, safety and control equipment.


Jacking and receiving shafts have been sited and
shown diagrammatically
on the Plans
with general
consideration to
overhead and underground utility conf
licts, driveway access, traffic impacts, a
maximum manhole spacing of
65
0 feet, and relationship to the geologic contact line
; all without
warranting that such siteing and diagrammatic sizing has mitigated conflicts with existing facilities or
optimized th
e selected means and methods for construction.


The Contractor shall determine the
exact size and configuration of the shafts to satisfy its selected means and methods and existing
site conditions.


Alternate shaft construction locations may be allowed as
specified herein and in
Section
701


JACKING AND RECEIVING SHAFTS
.




700
-
1.2 Definitions.


City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


166

Annular Space
:

The open volume created by the difference in the radial distances as measured
from the outside radius of the jacking pipe

or casing

to the excavate
d hole along the entire pipeline.
The distance includes the MTBM's over cut.


Carrier Pipe
: A pipe, installed in casing, which conveys sewage.


Casing (
P
ipe):

A pipe, typically made of steel, used to support a tunnel in which the product or
carrier pipe

is later inserted.


Compression Ring/Packer
:


A wood ring fitted between the end bearing area of the bell and spigot
to help distribute applied loads more uniformly. Packers are also referred to as compression rings.


Co
nta
c
t
Grouting
:


Grou
tin
g
outsid
e
of
th
e cas
in
g
pip
e
t
o
fill
voids and assure that
inti
mate
contact
for
l
oad
transfer
b
etwee
n
the
cas
in
g
pipe
a
nd th
e
native
h
ost
material ha
s
been achieved.


Controls
: The system that synchronizes excavation, removal of excavated material, and jacking of

pipe to maintain overall balance to provide complete and adequate ground support at all times.


Cutter

H
ead
: Any rotating tool or system of tools on a common support which excavates at the face
of a bore.


Earth Pressure Balance Machine
: An earth pressu
re balance type of microtunneling or tunneling
machine in which mechanical pressure is applied to the material at the face and controlled to
provide the correct counter
-
balance to earth pressures in order to prevent heave or subsidence.


Emerge
nc
y
Recovery

Shaft/Pit
:

A vertical
excavat
ion
required for
the
removal or repair of the trench
les
s
construction equipment.

T
h
e

location of an
emergency s
h
aft
is determined by construction
nece
ss
ity
and typica
ll
y will

not h
a
ve permanent
civil
s
tructures con
s
tructed
in the
s
h
aft.


Face:


The
locati
on where excavat
i
on
i
s
taking place
and
initial
s
upport ha
s
not
yet
b
ee
n installed
in
whole
or
part
.


Fu
ll
Face Control:


Co
mplete
and
unint
errupted
mechanical support
of
th
e excavated
Face.


Geologic Contact Line
: An inter
face between two geological strata.


Guidance System
: A system that relates the actual position of the MTBM to a design reference,
often a laser beam transmitted from the jacking shaft along the centerline of the pipe to a target
mounted in the shield.


I
n
adverte
nt Return
:


The
l
oss
of
drillin
g
fluid
,
including
s
lu
rry
a
nd
lu
brication
,
from
th
e s
lu
rry or
l
ubr
i
cation
sys
tem.

A common
form of
inadv
e
rtent r
e
turn
,
where the
fluid

r
eac
h
es
the
s
urface
or
waterway,
i
s commo
nl
y ca
ll
ed a
"Frac
-
out."


Intermediate J
acking Station (IJS):


A fabricated steel cylinder fitted with hydraulic cylinders
,

which
is incorporated into a pipeline between two pipe segments. Its function is to distribute the jacking
forces over the pipe string on long drives.


Jacking Frame
: A
structural component that houses the hydraulic cylinders used to propel the
microtunneling machine and pipeline. The jacking frame serves to distribute the thrust load to the
pipeline and the reaction load to the shaft wall or thrust wall.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


167


Jacking Pipe
:

A specialty pipe that is engineered and manufactured with a smooth outer wall and
watertight joints.


The pipe is specifically designed to be “direct
-
jacked” through the ground and may
also serve as a carrier or product pipe.


Jacking/Access Shaft
: Excav
ation from which trenchless technology equipment is launched and
driven.


Jacking Shield
: A fabricated steel cylinder from within which the excavation is carried out either by
hand or machine. Incorporated within the shield are facilities that allow it
to be adjusted to control
line and grade.


Laser:

An optical system projecting a beam onto a target to provide guidance reference for the
excavation.


Lubricant (
Lubrication
)
:

A fluid, normally bentonite and/or polymers, used to reduce
skin friction on
t
he j
acking pipe and fill the annular space

between the jacking pipe and the native unexcavated
material.


Lubrication/Grout Port
: An engineered opening through the jacking pipe/casing sidewall with a one
-
way valve installed in the pipe wall to allow the l
ubricant/grout to flow into the annular space and
prevent the return flow of the lubricant/grout into the installation system or the inside of the jacking
pipe/casing.


Maximum Allowable Jacking Force
:

The largest jacking load that the jacked pipe or casi
ng can
accept allowing for an appropriate factor of safety.


Maximum Anticipated Jacking Force
:

The largest theoretical jacking force required to advance the
pipe and machine from one location to another.


Microtunneling:

A remotely controlled, guided pi
pe
-
jacking process that provides continuous support
to the excavation face. The microtunneling process provides ability to control excavation face
stability by applying mechanical and fluid pressure to counterbalance the earth and naturally
occurring hydr
ostatic pressure.


Microtunnel Boring Machine (MTBM):

A remotely controlled, steerable, laser guided microtunnel
boring machine consisting of an articulated boring machine shield and a rotating cutting head.


Obstruction:

A
hard object with principal dim
ension greater than
6
-
inches
that lies either fully or
partially in the direct path of the MTBM
,
prevents its progress

and

has a
n

unconfined compressive
strength (UCS)
equal to or greater than
30,000 psi
.


Obstruction Removal by Surface Drilling
:

A contin
gency activity which may be implemented to
remove obstructions
by mobilizing a drill rig
to drill or core

vertically from the ground surface down to
and through
an

obstruction to an elevation below the path of the MTBM.



Obstruction Removal Shaft:


A vert
ical
excavat
ion
required for the removal
of
a
n obstruction.

T
h
e

location of the

s
h
aft
is determined by construction nece
ss
ity
and typica
ll
y will

not h
a
ve permanent
civil
s
tructures con
s
tructed in the
s
h
aft.


Overcut:

The radial distance between the excav
ated hole and the outside radius of the MTBM.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


168


Pipe Jacking:


Construction of a
pipeline by hydraulically jacking
consecutive
sect
i
on
s
of

jacking
pipe through
the
ground behind a shield or TBM
.


Pipe String:


The succession of
joined individual
pipes

b
e
in
g

u
sed
to
advan
ce
t
h
e
excavation
equipment and support
the tunnel.


Principal Dimension
: The largest of the three dimensions of an object.


Product Pipe (Carrier Pipe):

As it relates to this Work, a pipe for conveyance of sewage.


Receiving/Exit Shaft
: E
xcavation shaft into which the trenchless technology equipment is driven
towards and recovered from.


Repair /
Recovery Shaft
:

A vertical
excavat
ion
required for the removal or repair of the trench
les
s
construction equipment.

T
h
e

location of an
emergenc
y s
h
aft
is determined by construction
nece
ss
ity
and typica
ll
y will

not h
a
ve permanent
civil
s
tructures con
s
tructed in the
s
h
aft.


Slurry
: A fluid,
a water/bentonite medium

in non
-
cohesive soils and a water or water/polymer
medium in cohesive soils, which
is used for the transportation of excavated materials and to balance
the naturally occurring hydrostatic pressure during microtunneling. Slurry may or may not contain
the materials being transported.


Slurry Chamber:

Located behind the cutting head of a
s
lurry microtunneling machine. E
xcavated
material is mixed with slurry in the chamber for transport to the surface.


Slurry Line:

A series of hoses or pipes that transport tunnel muck and slurry from the face of a slurry
microtunneling machine to the gro
und surface for separation and return it to the cutter face.


Slurry Pressure Balance Machine:

A microtunneling system which uses a low pressure fluid to
stabilize the ground and balance hydrostatic water pressure at the face of the tunnel and to transpor
t
the excavated spoil to the surface.


Slurry Separation
: A process where excavated material is separated from the circulating slurry.


Spoil
: Earth, rock, and other materials removed during tunneling.


Surface Settlement Points
: Survey Control Points t
o be established at the ground surface, below
the ground surface, or on manmade structures along the pipe alignment used for monitoring surface
settlement due to subsurface excavation.


Thrust Block:

An engineered structure located between the jacking fr
ame and the shaft wall
intended to spread the jacking force developed by the hydraulic cylinders over a larger surface area.


Thrust Ring
: A fabricated ring that is mounted on the face of the jacking frame. It is intended to
transfer the jacking load fro
m the jacking frame to the thrust bearing area of the pipe section being
jacked.


Trenchless Technology Equipment
: Equipment used to install the product pipe without the use of a
trench cut from the point of origin to the destination. The equipment inclu
des, but is not limited to,
tunneling and drilling.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


169


Water Jetting
: Cleansing mechanism of the
cutter head

where high
-
pressure water is sprayed from
nozzles in the
cutter head

to help remove

cohesive soils.



7
00
-
1.
3

Design

Requirements.


Line and
G
rade:


The casing pipe shall be installed within 2
inches

in horizontal alignment and 1
inch

in vertical elevation.

The casing pipe shall not be located outside of the permanent easement.
Ther
e

shall be no reverse fall and no ponding of water.


Geotechnical R
eport
:

Tunnel and shaft design shall rely upon the conditions identified within the
Geotechnical

Report.


Jacking System:


The installed jacking system capacity shall exceed the maximum anticipated
jacking

forces by at least
5
0%.


The Contractor shall de
termine the maximum anticipated
construction loads, including maximum anticipated jacking force, and incorporate the anticipated
loads in the jacking pipe design.

The jacking pipe load capacity shall
exceed the maximum
anticipated jacking forces by at lea
st
5
0%.


Intermediate Jacking Stations (IJS)
:

The implementation of IJS shall be avoided in all situations and
shall only be implemented with prior authorization from the Engineer.


Lubrication System:


All jacking activities requires the use of a lubri
cant designed for the anticipated
ground conditions.

Lubrication shall be injected at the tail of the MTBM.


Dewatering:


Dewatering to lower the ground water shall not be permitted within 100 feet of the

microtunnel alignment

until after all microtunnel
activities have been completed
.

Sump pumping at
the bottom of the shaft is permitted for the removal of

storm

water, incidental, and construction
water.


Excavations:


E
xcavations
in excess of

4 feet s
hall not be perm
itted within 100 feet of the

microtunn
el alignment until after the microtunnel work is completed.

Potholing for utilities

and
excavation for instrumemtation

is

perm
itted.



700
-
1.
4

Allowable Settlement Heave.


Allowable Settlement/Heave
: Shall be as specified in Section
704


INSTRUMENTATION

AND
MONITORING.



700
-
1.
5

Surveys.


A professional surveyor licensed by the State of California and employed by the Contractor shall
conduct all surveys.



700
-
1.
6

Reference
Codes
and Standards.


Cal/OSHA, California Code of Regulations, Title 8, Indust
rial Relations, Chapter 4, Division of
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


170

Industrial Safety, Subchapter 4, Construction Safety Orders; and Subchapter 20, Tunnel Safety
Orders.


Occupational Safety and Health Administration (OSHA) Regulations and Standards for Underground
Construction (29 CF
R Part 1926, Subpart Section 1926.800, final rule dated June 9, 1989).



700
-
1.
7

Quality Assurance


Subcontracted
work does not qualify a
s
experience
.

Requirement
s
shall
b
e
at the time
of
bid
and
remain in
force
though completion of the project.



Contra
ctor’s Experience:


The Contractor performing the
microtunneling

work shall:

Have
successfully completed two microtunneling projects with jacking pIpe between 24 inches ID and 48
inches OD; Have successfully completed two microtunneling projects with the
same type of casing
pipe material as required for this project; Have successfully completed two microtunneling projects
in similar ground conditions

as measured by

soil type
, N
-
values

and hydrostatic head, as anticipated
on this project; Have successfully
completed a microtunnel drive length
s

of at least
600 feet
.


Microtunneling Project Superintendent::


The Microtunneling Project Superintendent shall have a
minimum of five years experience in the installation of pipelines using Microtunneling methods; sha
ll
have a minimum of five projects, with each project consisting of at least 500 feet of pipe using
Microtunneling methods; shall have successfully completed two microtunneling projects with pIpe
installed between 24 inches ID and 48 inches OD; shall have
successfully completed two
microtunneling projects with the same type of pipe

material as required for this project; shall have
successfully completed two microtunneling projects in similar ground conditions

as measured by

soil
type
, N
-
values

and hydrostat
ic head
, as to tho
se anticipated on this project
.


MTBM Operator’s Experience:


The MTBM Operator shall have a minimum of f
our

years experience
in the installation of pipelines using Microtunneling methods; shall have a minimum of
eight

projects,
with each

project consisting of at least
6
00 feet of pipe using Microtunneling methods shall have
successfully completed two microtunneling projects with pipe between 24 inches ID and 48 inches
OD
; shall have

successfully completed two microtunneling projects with
the same type of

casing
pipe material as required for this project
; shall h
ave successfully completed two microtunneling
projects in similar ground

conditions

as measured by

soil type
, N
-
values

and hydrostatic head
, as to
those anticipated on this project
;

shall have o
perated a MTBM similar to the one proposed for this
project
.


Microtunneling

Engineer:


The
Microtunneling

Engineer shall be a
P
rofessional
E
ngineer licensed by
the State of

California.

Experience shall include
microtunneling

design calculati
ons on five

Microtunneling

projects within the last five years.



Surveyor:


The
Surveyor shall be a
P
rofessional
S
urveyor licensed by the State of California; with

experience in underground surveying.


Experience shall include the transfer of points and

l
ine
from
the surface to below ground surface on five tunnel projects within the last five

years.



700
-
1.
8

Submittals.


The contractor shall submit the following in accordance with
Section
2
-
5.3


Submittals.



City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


171

General:

Submit the following within five wor
king days following the Notice to Proceed: Organization
Chart showing the Project Superintendent, Shield and Tunnel Equipment Operators, and Site Safety
Officer and the Project Surveyor(s).

A b
rief description and sketches of the tunneling system
illustra
ting the design, layout, and operation of each system component including

e
xcavation
method, mucking removal system, guidance and controls, personnel access, and utilities. Address
as a minimum all tunnels.


Experience records
: Contractor shall submit in
accordance with
Section 700
-
1.
7


Quality
Assurance
.


The experience record shall include name of project, the agency that contracted for the
project, names of contact including all contact information, jacking pipe material, jacking pipe
outside diameter,
soil conditions, longest drive planned and completed, and total footage planned
and completed.


MTBM Launch and Retrieval Plan:

Contractor shall submit its operating plans for MTBM launch
commencing with any modification to the designed shoring and ending
with first pipe jacked into the
ground.

The launch plan shall
stabilize the ground

so that no more than 1.0 cubic yards of ground
enter the shaft and

there is

no
measurable

ground movement on the surface directly above the
tunnel; shall prevent
water from

enter
in
g
the
s
haft
at a rate greater
th
an
5 gallons per minute
; shall
prevent MTB
M from deviating from acceptable line and grade
.


The
o
perating plans for retrieval
shall commence

with any modification to the
desi
g
ned
shoring

and
end

with first pipe jacke
d
penetrating into the receivin
g

shaft.

The plan shall stabilize the ground so
that
no
more

than
1.0
cubic yards of ground enter
s

th
e s
haft

and
no
measurable
ground
movement
occurs
on
the
surface
directly
above
the tunnel
; shall
prevent water from
enterin
g the shaft at a
rate
greater
than
5 gallons
per minute
.


Jacking
Pipe Information:


The Contractor shall submit Jacking P
ipe
Capacity C
alcu
l
ations stamped
and signed
by
a
licen
sed
Ca
li
fornia

P
rofessional
E
ngineer (PE)
;

Drawings

showing
dimensions u
se
d
in
jacking
pipe
capacity calcu
l
ations and

specifically
identifying the
Factor of Safety
;
Jacking
force
ca
l
culations shall
spec
ifically identify
source of equation
,
so
urc
e

of friction
factor
,
friction factor, and
the
Factor of Safety.

All e
quation
s

and factor
s

shall
be
from a widely accepted
industry
source.



Maximum Anticipated Jacking Loads
:

The
Contractor shall
submit
calculations stamped and signed
by a licensed California

P
rofessional
E
ngineer (PE) which
determine
the maximum anticipated
construction
lo
ad
s,

including jacking forces
,
and
certify

that the
anticipated
l
oads
are
within the limits
of, and consistent with the manufacturer’s jacking pipe design and installation recommendations.

Any
jacking pipe
that
has

a special
manufacturing property
e
.
g
.
pi
pe
stiffne
ss
or

jacking
capacity,
shall
have
a
different
colored stripe
red
,
blue
,
green
markin
g

for

each
non
-
sta
ndard
property on the
inside
and outside such
that
the pipe
ca
n

be
readily
id
entified
on
the
surface or when
placed in the
ground.


Standard
s
h
all

be the most prevalent pipe
o
rdered
as
measured by
pipe ID
.



Lubrication
L
og
:


The Contractor shall submit a Lubrication Log which
s
hall include
date
,
s
hift
,
number
of batches mixed
,
and operat
or.


The
Lubrication
L
og
shal
l
include
by
pipe
number
,
th
e
volume
,
injection
pressure
,
a
nd

the
operator
.


Pipe
Lay

Schedule
: The Pipe Lay Schedule

s
hall include

e
ach
pipe
on every drive
i
s
to
be marked
with consecutive
numb
e
r
s
in
s
id
e
and

outside as it
i
s
placed for
j
ack
ing
beginning with

the number 1.
Specials sha
ll be marked as follows
:

t
he Special A
s
hall
be marked with the sequential
pipe number
followed b
y
the
letter
"A" and the Special
"B
"
shall be marked with the sequential pipe
number
followed by
th
e
letter
"B
" (e
.
g
.
if the
IJS is
to
be l
ocated
between pip
e
s

18 &
19
,
the Spec
ial
"A"
sha
ll
b
e
numbered 18
-
A
and
the
Special "B
"
19
-
B
.
).

All
m
arkings shall be acceptable
to
E
ngineer.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


172


Microtunneling Process Monitoring and
Contingency

Plans:


The Contractor shall submit monitoring

and contingency
plans
which inc
lude
:

Slurry and lubrication sampling measurements and frequency
for pH, sand

content,

and
viscosity limits, gel strength, and density for each soil type
;
Equipment
recovery method
s

including tunneling, shaft sinking, groundwater

control, and water
-
tight
tunnel
initial support methods.


Obst
ruction

removal methods and descriptions, which shall include
ob
struction

removal shafts, obst
ruction

removal by surface

drilling

and associated contingencies.

Laser operational

parameters observed, measured,
and record
ed to determine if

the laser has
moved or if heat distortion is affecting the guidance.


Jacking operational parameters observed,
measured, and recorded to determine if

jacking forces are increasing rapidly and reasonable
concern exists for

completing the
drive.


Slurry and lubrication operational parameters observed,
measured, and recorded

to determine if an inadvertent return may be
occurring
.


Plan shall include a

minimum of a four hour shutdown in the case of an inadvertent return occurring.


An
inadver
t
ent
return action plan including cleanup methods, emergency telephone

numbers, sources of equ
ipment
and materials needed for
containment and cleanup,

and corrective actions including reducing
operating pressures.


Jacking Reports:


Jacking reports shall

b
e submitted for each shift and shall

include, at a minimum,
the

Date, Project Name, Time of Measurement, Observations for Settlement and Heave,
Resetting
or adjusting the laser and the affect to lane and grade
,
Printed name of operator and signature
,
Numbe
r of each pipe installed and length of pipe
,
Start and end time for each pipe joint
,
Position of
IJS in the installed pipeline
,
Start and finish times for each crew each day.


Jacking reports shall
also
include, at a
minimum
, the following information for
three

recording points
of measurements for each pipe segment up to and including 10 feet

long.

The first recording point
shall be within one foot of the start, second recording

point shall be ne
ar the midpoint, and third
recording point shall be within on
e foot of the

end.

For pipe segments longer than 10 feet add one
recording point at the midpoint

between the first and second recording points and add one recording
point at the

midpoint between the second and third recording points for a total of five re
cording

p
oints.


For each of the record and provide the units of measure for p
osition of

the

MTBM in relation
to design line and grade
, m
aximum jacking force exerted by the main jacks

m
aximum jacking force
exerted by each IJS
, p
osition
of
s
teering jacks
, i
nclination
and
roll of the
cutter
h
ea
d
, t
orque on
cutter head
, f
ac
e
pres
s
ure
of

slurr
y
, v
elocity and
volume
of
sluny
per time unit
, e
arth pressure
,
j
acking distance
and speed
,
w
ater jetting op
e
rating parameters including maximum pre
ssure,
volume
,
and

opera
ting
duration
.


If
an
automated data recording
sys
tem is available on the microtunneling
system

supplied
,
it
shall
be
operated
for
the duration of the project.


Construction Method and Sequence of Operations
: Contractor shall provide a description of the
proposed method of construction and the sequence of operations to be performed during
construction. This submittal shall include the following:


A general description and schedule of the microtunneling procedure including, but not limited
to, shaft constr
uction, set
-
up of microtunneling equipment, method of spoil removal, spoil
disposal, disposal location, methods of protection and maintenance of project site, and
groundwater control
methods.


Preprinted machine specifications or a letter from the microtu
nneling machine manufacturer
demonstrating that the selected machine(s) is capable of progressing through the anticipated
soil conditions including, but not limited to, similar soil type, soil strength as measured by "N"
City of Vista
, C.I.P. No. 807
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173

values,

and hydrostatic head.


Wor
king Drawings/Work Plan
:


Layout of jacking and receiving

shafts, jacking equipment within the
shaft, and above ground equipment at each shaft location. Orientation of the manhole within the
shaft shall be included.

Shop drawings of tunnel machine, inclu
ding configuration of cutter head
and overcut tolerances. Cutter

head drawing shall confirm that the machine is capable of ingesting
the principal dimension as defined by an
obstruction.

Shaft

ventilation system details.


Pipe
lubrication system details
and proposed materials to be used for lubrication, including proposed
materials if saline water is encountered as defined by manufacturer's preprinted material.


Electrical
system, lighting system, and onsite power generation.


Grade and alignment control
system details
,
operating parameters, and monitoring requirements
.


Groundwater
C
ontrol
P
rovisions of
T
unneling
M
achine
.


Details of slurry system and soil separation
methods including proposed slurry formulations and calculations of the system capacity to

handle
flows at all proposed distances and changes of elevations to and from the tunneling machin
e.

Submit Material Safety Data Sheet (MSDS) for slurry additives.


Use NSF 060 or equal, Clean
Water
-
approved materials only.


Jacking
S
ystem
D
etails
:


Submi
t jacking system details,
intermediate jacking stations and their
proposed spacing, method of operation, thrust capacity and sleeve details, plus method of control to
prevent the maximum allowable jacking force from being exceeded.


Lubrication System
:
Des
cription of lubrication mix equipment and procedure for lubricating the pipe
during jacking operations, including estimated volume for the anticipated soils.


Submit materials to
be used for lubrication

and mix formulations
, including materials if saline w
ater is encountered.
Submit Material Safety Data Sheet (MSDS) for lubricant additives.


Use NSF 060 or equal, Clean
Water
-
approved materials only.

Demonstrate that the lubrication delivery system shall have
sufficient pressure and volume for lubrication t
o perform as intended and prevent inadvertent
returns.

Include pressure gauge and volumetric gauge locations.

Submit a sample lubrication log
sheet.


Contact Grout:


For jacked pipes in excess of 30
-
inches in outside diameter t
he Contractor shall
furnish

an
annular space grout mix, equipment

description
, and procedure for grouting the casing
pipe in place after completion of the tunneling process. Include system drawing, grout formulation,
pressure

gauge locations
,
volumetric monitoring procedures,
MSDS,

test procedures, and
theoretical injection pressure
calculations.


Casing Pipe

/ Jacking Pipe
:


Contractor shall submit t
heoretical jacking force calculations and pipe
material calculations
.

The j
acking force calculations shall be stamped and signed by a

licensed

Califo
rnia
P
rofessional
E
ngineer (PE).


Contractor shall determine the maximum anticipated
construction loads, including jacking forces, and
ensure that the anticipated loads are implemented
in
accordance with
the manufacturer's design of the pip
e
.


The pipe manufacturer's submittal shall
be signed and stamped by a PE. The PE signing and stamping for the pipe manufacturer shall be
registered in the US. The submittal shall include calculations showing maximum allowable jacking
force including Fac
tor of Safety.
A d
rawing of
the
casing

pipe / jacking pipe

with
the
lubrication/grout
ports shown. Ports are to be located such that they are alternating left and right 15 degrees off
vertical as measured from the crown
and not more than 10 feet between
ports as measured along
the crown.


Intermediate Jacking Stations
:
Intermediate Jacking Stations (IJS) are required if the maximum
anticipated jacking force exceeds 80% of the maximum allowable jacking force or the main jacks do
City of Vista
, C.I.P. No. 807
7

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4002


174

not exceed the anticipated
jacking force by at least 20%. Submit IJS details including number of
stations, location, and jacking force, if IJS are required.


Contingency Plans
:


Submit a

proposed contingency plan for potential situations that may occur
during tunneling operations s
hall be provi
ded for the following scenarios:


1.

Spoils do not settle/separate with the equipment on site.


2.

The MTBM hits an obstruction.


3.

The target laser is distorted by heat and/or humidity or has been knocked out of alignment.
The Contractor shall des
cribe which operational parameters are
observed/measured/recorded so that it can be determined if the above are occurring or
have just occurred.


4.

The jacking pressures start to move up rapidly and reasonable concern exists for
completing jacking operations

to the reception shaft.


5.

Tunneling operations cause settle
ment

or heave beyond the maximum allowable tolerance
per Section
704

INSTRUMENTATION AND MONITORING
.


6.

The MTBM "freezes" within a typical pipe reach during jacking opera
tions.


7.

The inflow of surfa
ce or groundwater exceeds the allowable inflow during shaft pentrations.



Injury or Illness Prevention Plan (
IIPP
)
:

Submit the Contractor’s
safety plan for personnel
conducting the tunneling or jacking operations and appurtenance installation
.


The plan
will be
retained on file for informational purposes only. No review will be furnished.

The Contractor shall be
solely responsible for all site safety and compliance with all job site safety requirements.


Survey
P
lans
:


Submit survey plans
including, but
not limited to, Settlement Surveying and
Monitoring Plan
,

Building and Structures Assessment Plan
,

Instrument locations
,

Initial Survey
,
Periodic Tunnel (MTBM Position) Surveys,
Final Survey.


Jacking Operations Log
: The Contractor shall
p
rovide a sample
of logging reports and daily reports
prior to beginning microtunneling
; t
ranscribe to paper and submit to the Agency at the end of each
shift the jacking operations log, which shall include, as a minimum

the

p
osition of the tunneling
machine in relation t
o design line and grade
, the n
umber of each pipe installed and length of pipe
,
the p
osition of IJS in the installed pipeline including exerted jacking force
, the m
aximum jacking
forces exerted on the pipe at each section
, the
starting

and finish times for
each crew shift each day
,
the p
osition of steering jacks
. i
nclination and torque of cutter head
, f
ace pressure of slurry
, h
ydraulic
pressure
,

v
olume of pipe lubricant used, its viscosity and pumping pressure
, o
bservations of
settlement or heaving.


If an a
utomated data recording system is available on the microtunneling system supplied it is to be
operational and the Contractor is to submit a sample of all information available for recording,
variations in sampling frequency, and available formats. All aut
omated data is to be provided to
Agency

on a daily basis in the requested format(s) at no additional charge to the
Agency
.


Contemporaneous Log:

The Contractor shall provide a contemporaneous log of all line and grade
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


175

checks, resets, and adjustments which

shall be independent of the “Jacking Reports”. The log shall
include:

1.

Date, time, pipe number, and person making adjustment.


2.

Measurements from immediately before adjustment.


3.

Measurements from immediately after adjustment.


4.

Survey data if adjustment is
performed based upon survey data.


5.

Daily verification of design slope and position.


6.

Date, time, pipe number, and person resetting line and grade control.


Contractor's Qualifications
: The qualifications shall be in accordance with
the
REFERENCES AND
QUAL
IFICATIONS

submittal with the Proposal Forms.


Review of Contractor's submittals
: The Agency's review shall not relieve the Contractor of any
assigned responsibilities. Submittal review period shall conform to Green Book requirements.


Right
-
of
-
way Submi
ttals
: Work to be performed within the C
ity of Vista

right
-
of
-
way requires C
ity

approval.



700
-
1.
9

Project Conditions.


Subsurface Information
: Contractor shall refer to the subsurface information detailed in
Appendix C


Geotechnical
Investigation.


T
he Contractor shall provide adequate ventilation in the tunnel and shafts at all times. Air quality
shall be tested in the shaft and tunnel immediately prior to each change in shift as well as prior to
personnel entry, and periodically thereafter as requi
red by law.


The Contractor shall provide adequate lighting in the tunnel shaft and around equipment being
utilized and shall thoroughly insulate any separate power and lighting circuits.



700
-
1.
10

Safety.


The Agency has obtained from the State of Cali
fornia, Department of Industrial Relations, Division of
Occupational Safety and Health Administration (Cal/OSHA) an underground classification for these
tunnels.


Refer to Appendix “
M

.


The Contractor shall conform to the Cal/OSHA Permit
requirements and
perform Work in conformance with all applicable laws and regulations.


The Contractor shall submit the safety plan for the Agency's information only. The Contractor is
solely responsible for safety on the project site; therefore, the submitted plan shall
not be subject to
approval by the Agency. At a minimum, the plan shall include:


1.

Safety plan for shaft access and exit, including ladders, stairs, walkways, and hoists.


2.

Protection against improper electrical, mechanical and hydraulic equipment
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


176

operations
.


3.

Protection against improper and unsafe lifting and hoisting equipment, practices, and
operation.


4.

Ventilation and lighting details.


5.

Monitoring for hazardous gases.


6.

Protection against flooding and means for emergency evacuation.


7.

Protection of shaft i
ncluding traffic barriers, accidental or unauthorized entry, and
falling objects.


8.

Safety supervision responsibilities.



700
-
2 PRODUCTS.

700
-
2.1 Materials.


Jacking Pipe
: Non
-
Pressure Jacking Pipe shall be specifically designed for microtunneling and
conform to appropriate specifications:


Steel
Casing
Pipe
: ASTM A139 Grade B, API 2B.

Joints shall be “Permalok” or approved equal. A
material submittal is required per Section
2
-
5.3 Submittals.


Outside Diameter
:

30

inches (
minimum
)


Carrier Pipe
: S
hall be in accordance with
Section
702
-
2.1 Materials
.



700
-
2.2 Lubrication.


Lubrication shall consist of bentonite and/or polymers and water. Contractor shall bear
the
expense
of obtaining water from a potable water source. Polymers shall be non toxi
c and shall not be used
until the MSDS is submitted and approved.

All products shall be NSF
-
60 compliant.



700
-
2.3 Slurry


The slurry shall consist of bentonite and/or polymers and water as appropriate for the soil type. The
Contractor shall bear the ex
pense of obtaining water from a potable water source. The polymers
shall be non
-
toxic and shall not be used until the
MSDS is submitted and approved. All products
shall be NSF
-
60 compliant.



700
-
2.
4

Equipment
.


The
C
ontractor shall be responsible for co
mpliance with the following requirements.


General:

The microtunneling system selected shall be specifically designed for excavating,
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


177

transporting and separating the soil materials that routinely could be encountered or expected along
the alignment of the

proposed sewer.


Microtunnel Boring Machine (MTBM):

Use equipment that is
manufactured for the specified tunnel
diameters,
capable of handling the various anticipated ground conditions. In addition, the MTBM
shall:


Be capable of maintaining the tunnel
face under wet, dry and adverse soil conditions and
preventing loss of ground through the machine. The MTBM must provide satisfactory support
of the excavated face at all time.


Be articulated to allow steering.


Incorporate a suitable seal between the MT
BM and the leading pipe.


Provide protection to the electric and hydraulic motors and operating controls against water
damage.


Use bi
-
directional drive on the cutter head wheel, and/or adjustable fins or other means, to
control roll.


Employ pressurized f
ace tunneling machines that exert a controllable pressure against the face,
during both excavation and shutdown periods, to support the excavation face, prevent groundwater
inflows, and prevent loss or heave of ground. A closed
-
face cutter

head designed t
o minimize loss
of ground shall be provided. Use pressurized face tunneling machines capable of controlling the
volume of excavated material removed at the tunnel face and coordinating the machine advance
rate to avoid over
-
excavation.


Automated Spoil Tr
ansportation
: Provide a MTBM that includes an automated spoil transportation
slurry system that balances the ground water pressures by the use of a slurry pressure balance
system. System shall be capable of adjustment required to maintain face stability
for the particular
soil condition encountered on the Work and shall monitor and continuously balance the ground
water pressure to prevent loss of slurry or uncontrolled ground water inflow.


The
Contractor shall

m
anage the pressure at the excavation face b
y use of the slurry pumps (which
may operate at variable speeds), pressure control valves, and a flow meter.


The Contractor shall i
nclude a slurry bypass unit in the system to allow the direction of flow to be
changed and isolated, as necessary.


The Cont
ractor shall furnish

a spoil transportation system that has the capability for removal of soil
in balance with excavation and advance.


Slurry Separation Equipment
: Provide a slurry separation system that is capable of the following:


Provide adequate sep
aration of the spoil from the slurry so that slurry with a sediment content
within the limits set by the Contractor's Work Plan can be returned to the cutting face for
reuse. Use a mechanical separation plant, including scalping screens, shaker screens, d
e
-
sanding and de
-
silting cones, and centrifuge if needed as deemed necessary by the project
plan. Appropriately contain spoil at the site prior to disposal.


City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


178

Use the type of separation process suited to the size of the tunnel being constructed, the soil
type being excavated, and the workspace available at each jacking shaft location for operating
the plant.


Carefully monitor the composition of the slurry to maintain the slurry weight, gel strength, and
viscosity limits defined by the Contractor's Work Pl
an.


Pipe Jacking Equipment:

Provide a MTBM operation that includes a pipe jacking system with the
following features:


Main hydraulic cylinders mounted in a jacking frame located in the jacking shaft used to push
the MTBM and pipe through the ground.


Ja
cking system that successively pushes the MTBM along with a string of connected pipes
towards a receiving shaft.


Sufficient jacking capacity to push the MTBM and the pipe string between the shaft locations
identified on the Shop Drawings.


Measures and re
cords hydraulic extension rates (inches/minute or mm/minute)
which are
synchronized with the excavation rate of the MTBM, as determined by the soil conditions.


Uniform distribution of jacking forces on the end of the pipe by use of thrust ring and packers
.

A pipe lubrication system that at all times lowers the friction developed on the surface of the
pipe during jacking.


Remote Control System
: Provide a MTBM that includes a remote control system with the following
features:


Allows for operation of the
system without the need for personnel to enter the tunnel. Has a
display available to the operator, showing the position of the shield in relation to a design
reference together with other information such as roll, pitch, complete guidance system, valve
p
ositions, thrust force, cutter head torque, rate of advance and installed length.


Integrates the system of excavation and removal of spoil and its simultaneous replacement by
pipe. As each pipe section is jacked forward, the control system synchronizes a
ll of the
operational functions of the system.


Active Direction Control
: Provide a MTBM that includes an active direction control system with the
following features:


1.

Controls line and grade by a guidance system.


2.

Is equipped with a high intensity laser
(maximum legal limit).


3.

Is capable of maintaining line and grade to the tolerances specified in Section
700
-
3.3

Installation.


4.

Provides active steering information that is monitored and transmitted to the operating
console. As a minimum, this information

shall include location of the laser beam on
the target and location of the cutter head.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


179


5.

Provides positioning and operation information to the operator on the control console.


6.

Provides a reference laser, or other approved device that indicates visually i
n the
jacking shaft that the directional control laser has not been accidentally moved.


Safety Equipment
: Provide all appropriate safety equipment as necessary for the Contractor's
method and operation of construction and as required by all applicable La
ws and Regulations.


Lubrication System
: Shall include pressure gauge accurate to 1 psi, volumetric gauge accurate to 1
cubic foot, and shut
-
off valve on the pump or at the point of injection.


Obstruction Removal by Surface Drilling
:

A contingency activ
ity which may be implemented to
remove obstructions by mobilizing a drill rig to drill or core vertically from the ground surface down to
and through an obstruction to an elevation below the path of the MTBM. Surface drilling systems
shall be capable of dr
illing or coring through hard material with an unconfined compressive strength
(UCS) of up to 60,000 psi.



700
-
3 EXECUTION.

700
-
3.1 Jacking and Receiving Shafts.


The Contractor shall be responsible for constructing jacking and receiving shafts for mic
rotunneling
in accordance with the requirements of Section
701


JACKING AND RECEIVING SHAFTS
.


The MTBM shall not be launched until the receiving shaft is complete and operational ready to
receive the MTBM.



700
-
3.2 Work Area Preparation
a
nd Maintenance.


The Contractor shall provide the Agency and its agent(s) access to the entire site, including shaft,
tunnel, and MTBM control cabin, when occupied by their personnel.


The Contractor shall be responsible for the following conditions:


Means and methods o
f tunneling and pipe jacking operations and safety of the Work, the
Contractor's employees, the public, and adjacent property, whether public or private.


Clean working conditions inside the jacking operation area, including removal of spoil, debris,
equip
ment, and other material not required for operations. Contractor shall not store pipe on
any City streets unless the Agency grants permission in writing. Contractor shall see that
streets are cleaned each day with a
street sweeper, Section
7
-
8 Work Site

Maintenance
.


Organization of microtunneling surface equipment for each drive in such a manner as to
enable proper operation at all times, to minimize impacts to property owners, and to maintain
traffic control patterns as specified in the
Section
7
-
10.1

Traffic and Access
.


Power generation equipment and any other equipment operating on or with fuel or lubrication
oils shall be provided with suitable oil and gas containment basins made of plastic lining and
sand bags to ensure no loss of oil to drains or

water courses or to contaminate the ground.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


180



700
-
3.3 Installation.


Locate Existing Utilities:


Prior to the initiation of shaft construction or tunneling operations the
Contractor shall determine the exact location of all existing utilities and substr
uctures which may
affect or be affected by its operations.


Alignment Establishment
: The Contractor shall be responsible for adherence to the following
requirements and conditions:


Retain a Professional Surveyor licensed in the
S
tate of California to sur
vey the control points
identified in the Contract Documents, exclusive of Agency provided control points indicated on
the drawings. Surveyor shall check baseline and benchmarks at the beginning of the Work
and report any errors or discrepancies to the Age
ncy.


Use the baseline and benchmarks shown on the Plans to furnish and maintain reference
control lines and grades for the sewer pipe construction. Use these lines and grades to
establish the exact location of the pipeline excavation, and structures.


D
etermine by exploratory excavation the horizontal location and invert elevation of all points of
connection prior to the initiation of all pipeline construction and tunneling activities.


Establish and be responsible for accuracy of control for the constr
uction of the entire Work,
including Access Shaft locations, structures, excavation, pipe alignment, and grade.


Establish control points sufficiently far from the tunnel operation not to be affected by ground
movement.


Check the primary control for the m
icrotunneling system against an aboveground undisturbed
reference at least once each week or not greater than
200
-
foot intervals of pipeline
constructed.


The Contractor shall submit the raw survey data within one (1) working day and
the surveyor’s certifi
ed plotted survey within (2) working days.


The Contractor shall provide the Engineer with access to the tunnel to perform its own
independent survey if determined necessary, at the sole discretion of the Engineer.

The
Contractor shall provide up to four

(4) hours of access to facilitate the independent survey, and
the costs for such access shall be considered included within the unit prices for
microtunneling.


Tolerances:

The Contractor shall adhere to the following requirement and conditions:


Record

the exact position of the MTBM at 50
-
foot intervals or a minimum of once per shift to
ensure the alignment is within the specified tolerances. Make the survey at the MTBM to allow
immediate correction of misalignment before allowable tolerances are excee
ded. The tunnel
guidance system may be used; however, select times to measure and record this information
after the air temperatures have stabilized throughout the pipe to ensure accurate readings.

The Contractor shall submit cumulative line and grade rec
ords
,

on a daily basis
,

that include
the daily before and after shift checks, daily adjustments, pipe number adjustments, and
survey adjustments. If an offset is used, the offset shall be duly noted.


City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


181

When the excavation is off line or grade, return to th
e design line and/or grade over the
remaining portion of the drive and at a rate of not more than 1
-
inch per 25 feet.


If allowable tolerances are exceeded, Contractor shall pay all costs for correction (redesign,
reconstruction, re
-
inspection). If redesi
gn is required, the Contractor shall obtain the services
of a Professional Engineer registered in the State of California for the redesign. The installed
pipe must be capable of meeting the design flow shown on the Plans. Plans showing the
changes shall
be submitted to the Agency for review.


Perform a
closed
-
loop
verification survey with a transit or total station of the installed pipe from
shaft to shaft after removal of the MTBM

in accordance with Section
700
-
3.7

Quality Control
.

Document measured co
nformance to design line and grade of the pipe together with locations
and deviation (distance and direction) of any out
-
of
-
tolerance locations. Comply with the
tolerance
requirements of
this Sub
-
Section.


Tunneling and Jacking of Pipe
: The Contractor s
hall adhere to the following requirements and
conditions:


Conduct tunneling operations in accordance with applicable safety rules and regulations and
use methods that include due regard for safety of workers, and protection for adjacent
structures, utilit
ies, and the public.


Keep tunnel excavation within the rights
-
of
-
way indicated on the Contract Drawings, within the
lines and grades designated on the Contract Drawings, and within the tolerances of
this Sub
-
Section.


Locate equipment powered by combustib
le fuels at suitable distances from shafts and protect
equipment to prevent the possibility of explosion and fire in shafts or the pipe.


Synchronize the rate of advance of the MTBM with the rate of spoil removed to avoid over
-
excavating.


Make the excavat
ion of a minimum sufficient size to permit pipe installation by jacking with
allowance for injection of the lubricant into the annular space. The annular space shall not
exceed
0.75
-
inch.


Maintain an envelope of lubricant around the exterior of the pipe
during jacking and excavation
operation to reduce the exterior friction and possibility of the pipe seizing in place.


Contractor shall not employ water

or polymer slurry

jetting of the ground to advance the pipe
without prior written approval of the Agenc
y.


Water jetting shall only be authorized while
tunneling within cohesive soils.


The Contractor shall
include a plan and mix designs for water
and polymer slurry jetting activities within its Contingency Plan submittal.

A
polymer slurry mix
shall be uti
lized in lieu of water
when operating within soils that have a clay content of less
than 20%.


The Contractor, at its option, with the Engineer’s acceptance
continue
microtunneling activities
24 hours/day, 7 days/week should jacking forces begin to exceed

80% of the maximum
allowable design forces.


If the pipe "freezes" and the MTBM and/or pipeline is unable to be moved, a recovery access
City of Vista
, C.I.P. No. 807
7

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4002


182

shaft may be permitted with the location subject to review by the Agency
.


The
microtunneling
bid price shall include

all costs associated with recovery of the MTBM, including but not limited
to permits, shaft construction, demolition and replacement, and utility relocation. Recovery
shaft construction shall be performed in accordance wit
h the requirements of Section
70
1

JACKING AND RECEIVING SHAFTS
.


In the event a section of pipe should be damaged during the jacking operation or joint failure
occurs, as evidenced by visible ground water inflow or other observations, use one of the
following procedures to correct the d
amage, as directed by the Agency, and at no additional
cost to the Agency:


Slightly damaged pipe that passes leakage test and maintains pipe barrel and joint structural
integrity, may, if access is possible, be repaired in place with a method approved by
the pipe
supplier and if the proposed technique is accepted by the Agency.


Severely damaged pipe, or pipe where joint failure is evident, shall be removed from the
excavation by surface excavation, except as noted above, or by jacking it through the
excav
ation and removing it at the receiving shaft. The removed pipe, after inspection and
found to be without defect, may be jacked a second time by being placed into the same pipe
string at the jacking shaft.


Obstructions During Microtunneling
:

The Contract
or shall be responsible for meeting the following
conditions:


Reference is made to the
Appendix C

Geotechnical
Investigation
.


Alluvial material consisting of
loose to medium dense, saturated, silty to clayey sand and granitic bedrock will be encountered

at
the elevations of the proposed micro
-
tunneled alignment
.


Nested cobbles may be present within the
alluvial materials.


The Contractor shall r
emove, clear or otherwise make it possible for the microtunneling system and
pipe to progress past or through

objects in accordance with the Contractor's submitted contingency
plan

as follows:


The Contractor’s system shall be capable of excavating through
all
soils and
hard materials,
cobble
, in
-
situ granitic rock, floaters and boulders
, alluvium, clay, sandy cl
ay gravel, which are
not defined as “obstructions”
.


Core stones
,

un
-
weather
ed and in
-
situ granitic rock,

floaters, cobbles and bo
u
lders left behind
during ancient erosion processes,

with a UCS in excess of 30,000 UCS

may be encountered
within the existing

tunnel alignment.

Provisions for the removal
these obstructions

shall be
incorporated into the Contractor’s contingency plans and shall

be paid for in accordance with

listed Alternate Unit Price Bid Items or
applicable provisions of Section
3

CHANGES IN

WORK
of the
Supplementary General

Provisions.


No additional compensation
will be paid
for removing, clearing, or otherwise making it possible for
the MTBM to progress past objects
which
are not obstructions
.



Should the construction of a
n obstruction

re
moval

shaft be required to
clear the alignment of

an
obstruction
, payment shall be made in accordance with the

listed
Alternate Unit Price Bid Item for
MTBM
Obstruction Removal

Shaft.

Payment for obstruction removal shafts shall
only
be paid if the
object

meets the definition of an obstruction
.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


183


It is anticipated that
many obstructions can/will

be removed in the course of the shaft
’s construction
.

Site specific utility relocations and a
dditional effort
(hammering, drilling, expansive

fracturing
, etc.)
,

wh
ich may be
required

to clear large or embedded
obstructions
,

shall be paid for in accordance with
applicable provisions of Section
3

CHANGES IN WORK

of the Supplementary General Provisions.

Such payment shall be in addition to the Alternate Unit Price Bi
d Item

for

Obstruction Removal
Shaft

.

Any demolition, removal and/or r
estoration of
existing a
sphalt concrete, PCC, landscaping
and planting improvements shall be included within the Alternative Unit Price Bid Item

for
Obstruction Removal Shaft
.


Should

obstruction removal by surface drilling be required to clear the alignment of an obstruction,
payment shall be made in accordance with the listed Alternate Unit Price Bid Item
s

for

O
bstruction
Removal by Surface D
rilling


and

Mobilization for Obstructio
n Removal by Surface Drilling

.


Payment shall only be made if the object meets the definition of an obstruction.


Payment for obstruction removal shafts

and
obstruction removal by surface drilling

shall be
subject
to the following requirements:


The Contr
actor shall n
otify the Agency immediately upon encountering an object that stops the
forward progress of the Work.


Upon written authorization by the Agency, proceed with removal of the object by means of
obstruction removal procedures in accordance with t
he Contractor's
contingency plan

and
Section
701

JACKING AND RECEIVING SHAFTS
.


The Contractor s
hall not carryout excavation within 5 feet of the front of the boring head
,

without the Agency's knowledge.


The proposal of alternative methods for removing,
clearing or otherwise making it possible for the
microtunneling system to progress past objects that does not allow for the visual observation and
measurement of the nature of the object to be made shall not be considered for additional payment.


The Cont
ractor shall grout the exterior annular space
outside of

initial ground support
system
with a

lean (1 part cement to 6 parts water) cement mix for all
jacked pipes in excess of 30
-
inches in
outside diameter
.



700
-
3.4 Noise Monitoring
a
nd Abatement.


Impl
ement measures necessary to mitigate noise impacts caused by the Work.
Comply with

Section
7
-
8.3 Noise Control
.
The following noise monitoring and abatement requirements are
specific to the microtunneling operation when the Contractor's power generation

and slurry
sep
aration equipment are operating:



1.

Monitor the ambient noise at the corner of the occupied building closest to the
generator and slurry separation equipment.


2.

Provide equipment with enclosures or construct portable sound barriers to minimi
ze
noise impact.


3.

Provide a generator with a "residential" silencer and acoustic enclosure.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


184


4.

Provide equipment with equipment mufflers, as needed, to mitigate the noise produced
from construction.


5.

Contractor may be required to rearrange equipment to minim
ize noise impact.


Shaft construction shall be exempt from the
above

req
uirements.



700
-
3.5 Disposal of Muck
a
nd Excess Material.


Remove muck and excavated material from the project site in accordance with the requirements of
Section
7
-
8


WORK SITE MA
INTENANCE
.


Locate and acquire a site for the legal disposal of muck and excess excavated material and dispose
of same in accordance with all applicable Laws and Regulations. Defend, indemnify, hold harmless
the Agency for all claims, demands, penalties,
fines, damage, loss, causes of action, proceedings,
liability, costs and expense including attorney's fees for failure to dispose of same in accordance
with all applicable Laws and Regulations.


Wet

tunnel spoils and excess tunnel process water shall be
tr
ansported exclusively
within
completely water tight sanitary
-
type end dumps only specifically designed for the transport of liquids
and wet materials
.


Transport within end dumps or
water trucks are

not permitted.



700
-
3.6 Site Cleanup.


Unless otherwise

shown or specified,
the
Contractor shall restore to their original condition all
existing surface improvements damaged or removed as a result of microtunneling operations.



700
-
3.7 Quality Control.


Perform a CCTV inspection of the completed
carrier / p
roduct
pipeline. Refer to
Section
702
-
3.3

Installation

of Carrier Pipe in Tunnel.


Perform a closed
-
loop verification survey with a transit or total station of the installed pipe from shaft
to shaft after removal of the MTBM in accordance with Section
70
2
-
3.3

Installation

of Carrier Pipe
in Tunnel
.

Document measured conformance to design line and grade of the pipe together with
locations and deviation (distance and direction) of any out
-
of
-
tolerance locations. Comply with the
tolerance requirements of
Section
702
-
3.3

Installation

of Carrier Pipe in Tunnel
.

Each length of
casing pipe shall be surveyed at two (2) points which shall be within two feet of each joint.



SECTION 701


JACKING AND RECEIVING SHAFTS


70
1
-
1 GENERAL.

70
1
-
1.1 Scope.


Perform a
ll work necessary for excavating, sheeting, shoring and supports shown, specified and
required to construct jacking and receiving shafts, and other shafts as needed to complete the
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


185

Work
.


Groundwater extraction (dewatering) shall not be performed within 1
00 feet of microtunneling shafts
or microtunneling activities until after all microtunneling has been completed.

All shafts, therefore,
shall be constructed utilizing methods, which do not rely on dewatering activities.


All microtunneling shafts shall b
e sealed and water
-
tight.
Maintain watertightness of all shafts as
required for proper operation of the tunneling equipment and its effects on the tunneling system.

Acceptable excavation support systems include interlocking sheet piles, auger excavated sh
afts with
CMP shoring, caisson, secant pipes and slurry walls.



Design, furnish, install, and maintain support systems, including all bracing and associated items
necessary to retain safe excavations and to control ground movements within specified limits
. Upon
completion of required tunnel construction, completely remove support systems as specified, and
restore shafts and staging sites.


Saw


cut and remove pavement; provide fences and signs for construction staging areas; design
and construct shaft exc
avations and excavation support systems; dispose of materials; control and
dispose surface water, ground water, and construction water; and restore site.


Assume sole responsibility for sizing the shaft excavations and construct shafts adequate for all
str
uctures required. Further, the allowable work area shall meet specifications of the Traffic Control
Plan, and shaft excavations shall conform to right
-
of
-
way requirements and width limitations. The
Agency shall have the right to approve shaft excavation
size.


Construct shafts as sited on the Contract Drawings unless the Agency approves otherwise. The
Contractor shall be responsible for all costs associated with relocation of shafts.


Relocate, support, or bypass all identified utilities required in the
performance of the work at no
additional cost to the Agency.



701
-
1.2 Quality Assurance.


Permits and Regulations
: Contractor shall:


Obtain all applicable permits for earthwork, work in roads, right
-
of
-
way, etc., as required by
local, state and federal

agencies.


Perform excavation work in compliance with applicable requirements of governing authorities
having jurisdiction.


Reference Standards and Codes
:


ASTM A 36, Specification for Structural Steel.


OSHA Standard, Title 29, Code of Federal Regulatio
ns, Part 1926, Section .650 (Subpart P
-

Excavations).


CAL/OSHA State of California Administrative Code, Title 8, Industrial Relations, Chapter 4,
Subchapter 4, Construction Safety Orders.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


186


Subsurface Information: Contractor shall refer to the subsurface

information detailed
in
Appendix C


Geotechnical Investigation.


Initial Survey of Existing Improvements
:
The Contractor shall

perform a sufficient level of surveying
detailing the area

around the shafts prior to beginning shaft design, demolition, excav
ation or shaft
construction,

so that all existing improvements can be returned to their original location and
elevation.
The survey shall also identify all adjacent underground utilities, which may need to be
protected and/or relocated to facilitate the wo
rk.

At a minimum all structures within 50 feet of the
shaft perimeter and all surface and subsurface improvements within 25 feet of the shaft perimeter.




701
-
1.3 Submittals.


Shop drawings for shaft excavations, excavation support systems, and other rel
ated information as
requested by the Agency. A Professional Engineer registered in the State of California who has a
minimum of five years experience in the structural design of earth retaining structures shall prepare
and seal the shop drawings. Submit
the following in accordance with the requirements of
Section
2
-
5.3

Submittals

and Section
2
-
5.
3.3 Shop Drawings
.


Provide name and qualifications of Contractor's engineer responsible for excavation support system
design.


Use submitted construction metho
d to install excavation support system design.


In shop drawings and design calculations, indicate arrangements of supports and construction
sequence for proposed support system(s). Show the elevation of struts, braces, or other supports
as related to the

depth of excavation at intermediate stages of construction. Provide details of
working slab, drains, and sump construction. Indicate sizes, shapes, and material specifications for
all support elements including lagging, if used. Calculations shall incl
ude estimates of likely
deflections or deformations of the support system and shaft bottom, along with maximum tolerable
values. Coordinate design and calculations with the no dewatering requirement.


For break
-
in and
break
-
out plans, indicate support ins
talled to transfer loads and maintain
excavation support and stability of the excavation when commencing tunneling operations and when
holing out in receiving shafts.


Thrust block design and details, including jacking force capacity.


For quality control
procedures, address materials testing requirements, proof
-
test and performance
test requirements for tiebacks, and excavation monitoring provisions.


Provide a site plan for each excavation indicating the location, excavation dimensions, site grading,
and
site development details for the excavation and all work areas, and the proposed limits of
disturbance surrounding each excavation.


Provide protection for adjacent facilities and utilities. Address all utilities within 25 feet and all
structures within 5
0 feet of excavations.


Furnish buoyancy calculations prepared by a P
rofessional
E
ngineer registered in
California
,
which

demonstrate that
the
shaft will not float out of the
ground.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


187


Show site drainage and groundwater control details with measures to con
trol, treat, handle, and
dispose of surface water runoff, groundwater, and construction water. Provide details of working
slab, subdrains, and sump construction.


Provide details of materials handling, stockpiling, and disposal sites for excavated materia
ls.


Monitor system to evaluate stability, safety, ground movements, and any nearby facilities and
structures that could be affected by the work.


Provide plans indicating removal of excavation supports and site restoration details. Submittal shall
clearl
y identify materials required to be left in
-
place following construction and shall be subject to
approval of the Agency.


Provide plans for environmental controls
, including SWPPP provisions
.


Provide copies of all documentation, releases, and permits requ
ired herein and necessary to
complete the work. Documentation, releases, and permits include, but are not limited to, imported
materials, material disposal, utility disturbances, and affected properties.


Submittals for work to be performed within C
ity of

Vista
right
-
of
-
way require
s

review
by
the City of
Vista.



701
-
1.4 Design Criteria.


The Contractor's Engineer shall comply with the following design criteria:


Shafts shall be designed to facilitate installation without lowering the ground water table.

Shafts shall be sealed and watertight,


Design shaft excavation support systems and working slabs to withstand earth pressures,
unrelieved hydrostatic pressures, bottom heave, equipment loads,
buoyant forces,
applicable
traffic and construction loads, and

other surcharge loads to allow for the safe construction of
the tunnel or jacked pipe without movement or settlement of the ground beyond specified
tolerances, and to prevent damage to, or movement of, adjacent structures, streets, utilities or
the newly
installed pipeline or structures. Design excavation support systems compatible with
the geologic conditions reported in
Appendix C

Geotechnical

Investigation.


Design the support system to minimize horizontal and vertical movements, and to protect
adjace
nt utilities from damage. Design support system to maintain the stability of the
excavation and to provide a factor of safety of at least 1.5 against sliding and against bottom
heave.


Design a working slab for each jacking shaft bottom to provide stable
support for guide rails,
thrust blocks, and other construction operations.


Locate shafts approximately where indicated on the Contract Drawings unless otherwise
approved by the Agency.


Provide temporary safety railing and fencing around shaft excavations
. Provide traffic control
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


188

around working areas and shafts as shown on the
Traffic Control Plans
.


Design excavation support systems in accordance with all applicable CAL/OSHA and OSHA
requirements.


Agency's review of the Contractor's plans and methods of

construction shall not relieve the
Contractor of the responsibility to provide and to maintain an adequate support system
achieving the specified requirements.



701
-
1.5 Materials
T
ransportation, Handling and Storage.


Material Storage:

Stockpile satis
factory excavated materials at locations approved by the Agency,
until required for backfill or fill. Place, grade, and shape

stockpiles for proper drainage.
Dispose of
excess soil material and waste materials as specified herein.



701
-
2 PRODUCTS.

701
-
2.1 Materials.


General:

All timber and structural steel used for the supporting systems, whether new or
used

shall
be sound and free from defects which may impair their strength.


Structural Steel:

Structural steel shall conform to ASTM A 36 or higher
strength, unless approved
otherwise.


Timber:

All timber shall be of structural grade with a minimum allowable flexural strength of 1,500
pounds per square inch (psi).


Shotcrete:

Shotcrete shall conform to the requirements of ACI 506.2. Minimum design
compressive
strength shall be as required but not less than 4,000 psi.



701
-
3 EXECUTION.

701
-
3.1 Shaft Size and Location.


Shaft Location:

The shaft location and function shall be as shown on the Plans, unless otherwise
approved by the Agency. Propose
d shafts at locations other than shown on the Plans shall comply
with the following conditions:


Alternate or additional shaft locations shall be defined as alternate jacking/receiving shaft
locations proposed by the Contractor. Intermediate shafts, recov
ery shafts, and obstruction
removal shafts shall be as defined in Section
700 MICROTUNNELING
.


Alternate shaft locations proposed by the Contractor shall not be located so the sole vehicle
access to adjacent property is closed. Locate shafts to minimize
public inconvenience and
impacts to existing facilities.


Shaft Size:

The Contractor shall be solely responsible for sizing the shafts. Shaft size shall be
adequate for construction of any permanent structures indicated on the Plans and shall provide
ade
quate room to meet the Contractor's operational requirements for tunnel construction and for
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


189

backfill. Contain shaft excavations within the public right
-
of
-
way and limit width by the allowable
work area shown by the Contract Drawings.


The Contractor shal
l obtain all approvals, permits and bear all costs related to constructing

the
shaft
s

including, but not limited to, traffic control, utility relocation, construction and
site
restoration.
A licensed
C
ivil
E
ngineer in the State of California shall sign an
d submit to the Agency for approval
revised traffic control
plans
, if necessary.



701
-
3.2 Unauthorized Excavation.


All excavations outside the lines and grades shown, together with the removal and disposal of the
associated material, shall be at Contrac
tor's expense, and in accordance with
Section

306
-
1.3

Backfill and Densification
.


Fill and compact to at least 95% relative compaction with select backfill or approved slurry backfill all
unauthorized excavations at Contractor's expense.



701
-
3.3 Utili
ty Conflicts / Relocation.


The Contractor shall be ultimately responsible for determining a plan of action, subject to the
approval of the Agency, for protecting and relocating, bypassing or supporting all identified and
unidentified utilities required to

construct the jacking and receiving shafts necessary to complete the
work.
The Contractor shall protect or relocate, as may be required, all
identified utilities at no
additional cost to the Agency.
Shafts may be located within
highly congested
areas of

utility
crossings. The shafts may be altered slightly from their planned locations dependent on the
Contractor's plan to
construct

the shafts and as allowed by the permits.


Utility relocation shall be in accordance with
Section
5
-
4

RELOCATION
.



701
-
3.4 Shaft Construction
,

General.


Shafts shall be constructed without dewatering or lowering the ground water table.


Shafts shall be sealed and watertight and
shall be constructed of materials that prevent water inflow.

Shafts with total water inflows o
f less than 5 gallons per minute before tunneling commences and
again after launch shall be considered watertight.


Shaft construction methods shall always ensure the safety of the work, Contractor's employees,
Agency's employees and inspectors, the public
, and adjacent property and improvements, whether
public or private.


Provide shaft excavations with a gravel base and a concrete working slab equipped with a sump to
pump out construction water and storm water.


Before beginning construction at any locati
on of this project, adequately protect existing structures,
utilities, trees, shrubs, and other existing facilities. Design excavation support systems to limit
deformations that could damage adjacent facilities including utilities and structures. The rep
air of, or
compensation for, damage to existing facilities, shall be at no additional cost to Agency.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


190


All welding shall conform to the applicable provisions of ANSI/AWS D1.1.


Install support system monitoring provisions as necessary to assure proper perf
ormance of the
work, to monitor the support system and the excavation, and to adhere to Shop Drawings. Monitor
performance of excavation support system for both horizontal and vertical deflections daily during
excavation, and at intervals not to exceed se
ven calendar days following the completion of
excavation work. If monitoring data indicates that deflections have exceeded estimated values, the
Agency shall be notified immediately.


Install excavation support systems in accordance with approved Shop Dra
wings.


If settlement or deflections of supports or shaft bottom indicate the support system requires
modification to prevent excessive movements, the Contractor's structural engineer shall redesign
and resubmit revised shop drawings and calculations to
the Agency at no additional cost.


Stockpiling of excavated material within the public right
-
of
-
way shall not be permitted.


The working slab may be left in place for manhole support, if the Agency approves the foundation
prior to placement of the slab and

no subsequent disturbance to the foundation occurs.


Shafts

shall be constructed with the shoring extending not more than 4 feet above the ground
surface

upon completion
.


Watertight gaskets and entrance seals are required for launch. Exit seals are requi
red if
groundwater could enter the shaft through the exit penetration. Penetration of the shaft wall is
restricted to allowing an additional 5 gallons per minute of
water during launch or retrieval. After
launch or retrieval total inflows must be reduced b
ack to less than 5 gallons per minute.



701
-
3.
5

Internal Bracing Support System.


The internal bracing support system shall include whalers, struts, and/or shores.


Provide struts with intermediate bracing as needed to enable them to carry maximum design

load
without distortion or buckling.


Include web stiffeners, plates, or angles as needed to prevent rotation, crippling, or buckling of
connections and points of bearing between structural steel members. Allow for eccentricities
caused by field fabricat
ion and assembly.


Install and maintain all bracing support members in tight contact with each other and with the
surface being supported.


Preload bracing members by jacking struts to 50 percent of the design load if necessary to control
shoring movement.



Preload bracing members in accordance with methods, procedures, and sequence as described on
the Shop Drawings. Coordinate excavation work with installation of bracing and preloading. Use
steel shims and steel wedges welded or bolted in place to main
tain the preloading force in the
bracing after release of the jacking equipment pressure. Install support and preload immediately
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


191

after installation and prior to continuing excavation.


Use procedures that produce uniform loading of bracing members withou
t eccentricities or over
-
stressing and distortion of members of system.



701
-
3.
6

Shaft Contruction Methods
.


Corrugated
Metal
Pipe
(CMP) in Drilled
Shaft:


CMP or steel
pipe
shall
be placed in a vertically
drilled
hole.

The drilled
hole
shall
be
within
design
tolerances
of vertical alignment,
diameter
,
and
designed depth.

Drilled
hole
shall
be
of sufficient size
to allow placing
of CMP without
damaging the
CMP.

CMP shall be true and
round
within design
tolerances
and of sufficient
length
to
line
entire

hole.

CMP shall
be
within
de
sig
n
tolerances of
plumb
.


Annular space shall
be
filled with grout of
sufficient strength and
flow
-
ability to provide

100%
contact to ground and CMP.

Grout shall
be
within
design tolerances
for strength.

Temporary ground su
pport shall
be provided
as
designed
.


The shaft
bottom
shall
be
an
integral
part of
the
entire shaft
design.

Shaft shall
not be

drained until
annular grout and
bottom plug have
reached
required
strength.


Interlocking
Sheet Piles
:


Interlocking
sheet
pile

shafts are to
have interlocking
grooves
that
are
demonstrated
to

suffic
iently
seal the shaft to inflowing ground conditions
.

The shaft
bottom
shall
be
an
integral part of the
entire shaft
design
.

Shaft shall
not b
e
drained
until
grout and
bottom
plug
ha
ve reached required strength
.

All steel subsurface ground support materials shall be removed
except for those
l
y
in
g

directly below the installed jacked pipe.


Contractor shall submit other construction method or combination of construction methods require
d
for completion of the shafts. Other methods may include interlocking sheet piles, interlocking grout
columns, tremie shaft bottoms, and soil mixing.



701
-
3.
7

Concrete Slurry Backfill
.


Jacking and receiving shaft
backfill shall be concrete “Trench Bac
kfill” 100
-
E
-
100 from Table 201
-
1.1.2A in subsection
201
-
1.1.2 Concrete Specified by Class and Alternate Cla
s
s
.



701
-
3.
8

Removal of Support System
.


Remove sheeting and bracing from excavations when complete. Perform removal in a manner that
avoids inj
ury to the work, existing street, adjacent utilities or structures. Removal shall be equal on
both sides of excavation to ensure no unequal loads occur on pipelines and manholes.


Defer removal of sheeting and bracing, where removal may cause soil to come

into contact with
concrete, until concrete has cured a minimum of 7 calendar days.


Remove all elements to the maximum extent practical.

In no case shall any elements be left in
place within 10 feet of the finished ground surface.



701
-
3.
9

Restoration
.


Site Restoration
:

Restore the work area disturbed by construction activities and repair any damage
City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


192

caused to existing utilities, to its original, or better, condition. Restore paved areas to original or
better condition.



701
-
3.1
0

Environmental Contr
ols
.


Ground Water Control:

Shafts shall be sealed to prevent the infiltration of ground water.


The Contractor shall be prepared to r
emove
any ground
water from excavation as fast as it
may
collect.


Provide and maintain pumps, sumps, suction and discha
rge lines, power supply and other system
components necessary to convey water away from excavations.


Surface Water Control:

Divert surface water runoff from the shaft and protect the shafts from
infiltration or flooding by surface water
.



E
quipment
and

materials shall

not

be stored on public streets or public property without written
permission from the Agency. Store materials and equipment only in
the
Contractor's laydown areas
and within the limits of the shaft excavation.



701
-
3.1
1

Well Removal
Procedures.


In accordance with California Department of Water Resources "California Well Standards


Bulletin
74
-
90"
and County of San Diego requirements,
destroy instrumentation wells, and groundwater
monitoring wells required for construction of shafts.

Submit documentation of well destruction to the
Agency for review prior to submission to the local permitting agency.


The top 5 feet shall be concrete. The pavement surface shall match existing adjacent surface
material.



701
-
3.1
2

Safety.


The Contra
ctor shall be solely responsible for safety. Place security fencing around the Contractor's
work area with appropriate signage and lighting. Construct a suitable guardrail barrier around the
periphery of the shaft, meeting applicable safety standards. P
roperly maintain the barrier throughout
the period the shaft remains open. Repair broken boards, supports, and structural members.


The Contractor shall completely cover shaft openings with steel plates and perimeter fencing
or other
suitable
security b
arrier
s

where no construction activity exists or
shafts are left

unattended by the Contractor's personnel.



701
-
3.1
3

Restoring and Resurfacing Existing Roadways and Facilities.


The Contractor shall restore pavement or roadways damaged by construction op
erations.



701
-
3.1
4

Disposal of all Materials.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


193


The Contractor shall haul away from the project site material removed from the excavations that
does not conform to the requirements for fill and also shall dispose of that material in compliance
with ordi
nances, codes, laws and regulations at no additional cost to the Agency. The Contractor
shall utilize highway legal trucks for the export of material from the project site and to a site secured
by the Contractor. No earth moving equipment or special cons
truction equipment, as defined in
Section 565, of the California Vehicle code shall be allowed for hauling material on public streets.


Wet tunnel spoils and excess tunnel process water shall be transported exclusively within
completely water tight sanitar
y
-
type end dumps specifically designed for the transport of liquids and
wet materials
.

Transport within end dumps or
water trucks are

not permitted.



SECTION 702


PIPE INSTALLATION IN TUNNEL (CARRIER PIPE)


70
2
-
1 GENERAL.

70
2
-
1.1 Scope.


The work spec
ified in this section shall consist of installing carrier pipe into the initial support system
(casing pipe or tunnel).


The work shall include all expenses, materials, incidentals and equipment necessary to deliver and
install on line and grade, all carri
er pipe segments into the constructed tunnel.



702
-
1.2 S
tandards, Codes, Specifications and Reports
.


Unless otherwise stated in the contract documents, Contractor shall comply with the following
standards, codes, specifications and reports.


American So
ciety of Mechanical Engineers (ASME).


Boiler and Pressure Vessel Code (BPVC).


Section VIII, Rules for Construction of Pressure Vessels, Division 1.



702
-
1.
3

Contractor Submittals
.


Contractor shall have a Civil or Structural Engineer registered in the
State of California prepare and
seal shop drawings

and calculations of static and dynamic loads

for installation of carrier pipe in the
tunnels.

The submittal shall identify the maximum installation jacking

force

or tensile force (for
pulling)

to be appli
ed during installation.

The casing spacers design shall be included in the
Engineer’s submittal.


Contractor shall submit

in accordance with Section
2
-
5.3

Submittals

all shop drawings and
submittals before any Work specified in the respective Shop Drawin
g and/or Submittals takes place.


Contractor shall submit detailed fabrication shop drawings of carrier pipe to be installed. In addition,
the Contractor shall include the following installation information:


City of Vista
, C.I.P. No. 807
7

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194

Carrier
P
ipe

Manufacturer’s written recommend
ations including

carrier pipe
transportation,
handling, installation, support, stulling, and blocking procedures. Include method of joining
pipe sections together.

The Contractor is required to follow the recommended procedures.


Method of grade control
to ensure final line and grade of the carrier pipe.


Carrier pipe laying schedule for the tunnels showing carrier pipe lengths, deflections, and
fittings to meet the actual excavated tunnel alignment. Demonstrate that proper clearances
exist for carrier p
ipe installation.


Details for installing the carrier pipe in the tunnel. Drawings
identifying
casing spacers

details,
floatation protection,
rails
,
stiffeners

and bell restraint to prevent “over
-
belling” of carrier pipe
.
Description of methods and equip
ment for installing and testing carrier pipe, installing carrier
pipe in shaft securing it in place, and placing backfill around carrier pipe.


Calculations

and/or appropriate certifications

from the
casing spacer
manufacturer certifying
that the
casing sp
acers
are designed and arranged in a manner capable of supporting the unit
weight of the carrier pipe per linear foot without failure, under the project conditions.
Each
length of carrier pipe shall be supported by a minimum of two casing spacers. The max
imum
casing spacer
separation shall not exceed 8 feet.


Quality Control Submittals
: Contractor shall submit the following:


Description of experience demonstrating required qualifications for installing similar type of
carrier pipe in tunnel. Submission
of project name and details, contact, and telephone number
for last three projects contracted within the last 5 years, including all projects contracted with
this Agency.


Certification from the carrier pipe manufacturer that proposed carrier pipe transpor
tation,
internal and external carrier pipe supports, stulling details,
casing spacer
details to prevent
flotation and to prevent deformation by temperature, and backfilling procedures are in
accordance with manufacturer’s printed recommendations and shall
not damage carrier pipe.
Calculations demonstrating that carrier pipe shall not be damaged during backfilling operations
due to hydrating temperature, flotation, or the fluid pressure of backfill. Calculations shall be
prepared and sealed by a Civil or S
tructural Engineer registered in the State of California.


PVC and HDPE carrier pipelines shall be filled with wate
r to minimize the

potential
for
deformation and
floatation from the heat of hydration and
buoyant
forces imparted on the
carrier pipeline dur
ing backfill.



702
-
1.
4

Quality Assurance.


The Contractor shall be responsible for the installer’s proper handling, transporting, placing,
installing, testing, and placing of backfill for all aspects of carrier pipe installation. The Contractor
shall b
e responsible for the installer’s demonstrating experience installing the carrier pipe in tunnels.


Tolerances
:
The carrier pipe t
olerances shall comply with the followings criteria:


Variation from Design Centerline: Plus or minus 1
-
inch maximum except a
t shafts.


City of Vista
, C.I.P. No. 807
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195

Variation from Design Grade: Plus or minus ½
-
inch maximum from indicated invert elevations

with no reverse fall

or ponding of water
.


Allowable rate of change
: Allowable rate of change shall not exceed:


Horizontal: Maximum of 1
-
inch in 30 fee
t.


Vertical: Maximum of 1
-
inch in 40 feet.


Clearance:


Carrier Pipe shall be installed within the casing pipe with a minimum clearance of 2
-
inch
e
s as measured between the inside casing wall and the
furthest

projection of the carrier pipe’s
out sidewall
or bell.


Safety Factor:


Carrier Pipe shall have a minimum factor of safety of 3.0 for backfill fluid pressure.


Casing Spacers shall have a minimum factor of safety of 2.0.



702
-
2 PRODUCTS.

702
-
2.1 Materials.


Timber for stulls, braces, and blocking

shall be Construction Grade Douglas Fir, and especially
selected for straightness. Timber need not be new but used lumber shall be of the same grade and
species specified for new lumber and shall be sound, and free from defects which might impair the
ser
viceability of the piece. Timber shall be stored where it can be easily inspected. Timber with
excessive knots, bark, holes, splits or other defects shall not be used.


Blocking shall be precast concrete, treated timber, or other non
-
degradable material.


Redwood skids shall not be allowed on this project.


The Contractor shall provide non
-
conductive casing
spacers
in any tunnel with a conductive initial
support system, and maintain separation of the carrier pipe, as shown on the Drawings. Casing
spacers

shall hold the carrier pipes securely within the tunnel and shall be fully restrained with
runners and/or wheels to support the pipes and facilitate carrier pipe installation. Casing
spacers
shall be designed and arranged in a manner, certified by the
ma
nufacturer that

shall be capable of
supporting the carrier pipe without failure during installation
, shall provide for the minimum thickness
of backfill after adjustment for line and grade control and shall not restrict the complete backfill of the
annular

space.

Casing spacers shall not have a riser or leg located at the invert or crown.

Legs and
risers shall be symmetrical about the vertical axis.


Carrier pipe shall be 2
0
-
inch PVC C905 DR 41 only.

Joints maybe either integral bell and
spigot or extru
ded with plain ends and butt
-
fused joints.


If e
xternal bell restraint or fitting restraint harnesses
are used for the installation of the carrier pipe in
the casing, they
shall be designed for PVC pipe, manufactured of ductile iron conforming to ASTM
A536
, coated with
shop primer
, consisting of a split serrated restraint ring with individually activated
gripping surfaces for the plain end of the pipe and a split bell ring fastened into a harness by an
array of restraining rods. The harnesses shall be EBAA

Iron, Inc. “Megalug”, Smith
-
Blair “Bell
-
Lock
Serrated Joint Restraints” or approved equal. The materials selected for joint restraint shall be
submitted per Section
2
-
5.3 Submittals.


City of Vista
, C.I.P. No. 807
7

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196

If

d
ouble nuts”
are used
on the external bell restraint or fitting r
estraint harnesses, the external bell
restraint harness shall be modified to grip the pipe on both sides of the bell and double nuts shall be
used on the restraining rods to prevent movement of the in the joint in either longitudinal direction.



702
-
3 EX
ECUTION.

702
-
3.1 Work Preparation.


Tunnel shall be inspected and accepted by the Agency prior to installation of carrier pipe.


A special inspection shall be required before the installation of carrier pipe by means of casing
centralizers to ensure the

casing is free from irregularities in roundness, casing welding
irregularities, and misaligned casing joints. These deficiencies shall be corrected and approved by
the Agency prior to the installation of the carrier pipe.


Carrier pipe installation sha
ll not commence until the Agency indicates tunnel and shaft excavations
have been stabilized and all deformations of the initial supports have been successfully controlled.


Install temporary drainage pipes and panning to control water infiltration that sh
all be detrimental to
the placement of cellular concrete or backfill concrete and any piping required for contact grouting
and air vents for the drainage and panning elements. When no longer needed, these drains shall
be grouted after the installation of
pipe and cellular concrete or backfill concrete.


All foreign material, including water, shall be removed from the tunnel to provide the minimum
thickness of cellular concrete or backfill concrete indicated on the Shop Drawings.


All utilities shall be rem
oved prior to the installation of carrier pipe in tunnel except for drainage
facilities and other provisions to control groundwater inflows.


Carrier pipe installation shall not commence until the Agency confirms in writing that tunnel
preparation and clea
n
-
up have been properly completed.



702
-
3.2 General Requirements.


Temporary ventilation, lighting, and other utilities in the tunnel shall be maintained throughout the
tunnel during installation of the carrier pipe and all subsequent operations.


Tunnel

groundwater inflows shall be controlled by means of cutoff grouting.


The carrier pipe shall be installed in the tunnel as indicated on the Shop Drawings and accepted
submittals for carrier pipe installation. The carrier pipe shall be installed without s
liding or dragging
in a manner that would damage the carrier pipe or its coatings and linings. Any damage to the
carrier pipe or its coatings and linings during transport and installation, for any reason, shall be
repaired to the satisfaction of the Agenc
y or replaced with a new section of carrier pipe at no
additional expense to the Agency.


The carrier pipe in the tunnel shall be supported utilizing spacers to prevent buckling, ovalling,
misalignment, and flotation in accordance with the recommendations
of the carrier pipe
manufacturer, and accepted submittals.


The Contractor shall implement bell restraint in accordance
with the manufacturer’s recommendations in order to prevent the “over
-
belling” of the joints during
City of Vista
, C.I.P. No. 807
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197

installation into the casing pipe.


Each section of carrier pipe shall be installed to the required line and grade without encroaching on
the minimum annular space indicated on the Shop Drawings. The spacing shall be sufficient to
preclude damage to the carrier pipe due to excessive deflect
ion or misalignment of carrier pipe.


The Contractor shall ensure that each carrier pipe section is firmly secured during placement of
backfill.


The carrier pipe shall be securely held in position in such manner as not to interfere with the
required work
at the joints.



702
-
3.3 Installation of Carrier Pipe in Tunnel.


Before installation of any section of carrier pipe, any foreign matter shall be removed from all joint
surfaces and from the entire outer surface of the carrier pipe, to leave thoroughly cl
ean surfaces for
bond of backfill.


The use of sledges for driving or hammering in such a manner as to injure any joint shall not be
allowed. Care shall be taken to prevent the carrier pipe from being in any way subjected to heavy
shocks. Sharp kinks, sc
ars, bends, or other injuries from hammering or other causes shall be cause
for rejection wherever, in the opinion of the
Engineer
, the presence of such deformation
may

cause
damage to the carrier pipe or joints.


The use of dogs or equivalent devices weld
ed to the carrier pipe for the purpose of forcing it into
position shall not be permitted.


Appropriate joint restraints
at each joint
shall be employed by the Contractor

to prevent the over
-
insertion or over
-
belling of the carrier pipe during installation

in the casing pipe.


After carrier pipe installation and backfilling is complete, the Contractor shall inspect carrier pipe in
accordance with
Section
500
-
1.1.5

Television Inspection

for damage and repair any damage to
the carrier pipe at no additional c
ost to the Agency. The Contractor shall provide the
Agency

with a
color
MPG format DVD and software FLEXIDATA/PIPE LOGIX
and a log sheet

or report

for each
pipe run.


Repair methods shall be submitted to the Agency for review prior to performing the rep
airs.


The Contractor shall perform Exfiltration Tests conforming to the requirements of
Section
306
-
1.4.2
Water Exfiltration Test.



SECTION 703


ANNULAR LOW DENSITY CELLULAR CONCRETE


703
-
1 GENERAL.

703
-
1.1 Scope.


This Section shall consist of speci
fications for the backfilling of the internal annular space located
between the casing pipe and the installed carrier pipe. All work, equipment, labor, materials and
incidentals to perform the tasks described in this specification section are included.

City of Vista
, C.I.P. No. 807
7

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198



703
-
1.2 Standards, Codes, Specifications and Reports.

General
: Unless otherwise stated in this specification or in related work section specification, the
Contractor shall comply with the following standards, codes, specifications and reports:

ACI 523.1R

Guide for Cast
-
In
-
Place Low
-
Density Concrete

ACI 523.3R

Guide for Cellular Concretes Above 50 pcf and for
Aggregate Concretes Above 50 pcf with Compressive
Strengths Less Than 2,500 psi

ASTM C 94

Standard Methods for Ready Mixed Concrete

ASTM C 138

Standa
rd Test Method for Unit Weight, Yield,

and Air
Content (Gravimetric)

of concrete

ASTM C 150

Specifications for Portland Cement

ASTM C 495

Standard Test Method for Compressive Strength of
Lightweight Insulating Concrete

ASTM C 567

Standard Test Method for U
nit Weight of Structural
Lightweight Concrete

ASTM C 618

Specifications for Fly Ash and Raw or Calcified Natural
Pozzolan for Use as a Mineral Admixture in Portland
Cement Concrete

ASTM C 796

Standard Method of Testing Foaming Agents for Use in
Producing C
ellular Concrete Using Preformed Foam

ASTM C 869

Standard Specification for Foaming Agents Used in
Making Preformed Foam for Cellular Concrete.



703
-
1.3 Definitions.


Low Density Cellular Concrete
: Lightweight hardened cementious material made from the
combination of concrete and a foaming agent with an oven
-
dried weight and compressive strength
as specified herein.


Casing Pipe
: As defined in Section
700 MICROTUNNELING
.


Manufacturer:

Cellular concrete foaming agent manufacturer's representative.


Ca
rrier Pipe
: The finished pipe which will be used to convey sewage; See Section
702 PIPE
INSTALLATION IN TUNNEL.



703
-
1.4 Design Criteria.


The Work specified in this Section shall include backfilling the annular space between the carrier
pipe and the c
asing pipe with low
-
density cellular concrete.


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, C.I.P. No. 807
7

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199


703
-
1.5 Contractor Submittals.


Pre
-
Construction Submittals
: Submit the following within five working days from the Notice to
Proceed:


Submit Qualifications of the grout Contractor and Manufacturer. Th
e Contractor shall have a
minimum of 5 years of experience in similar type of grouting work. The Manufacturer shall
provide letters of recommendation from three previously successful jobs of a similar nature.


Product Data for each type of cellular concre
te proposed for use
. Submittal shall include for each
mix design:


1.

Type, brand, source, and amounts of cement, Pozzolans, admixtures, and other
additives.


2.

Source and amount of water.


3.

Representative samples of materials for materials testing and mix prop
ortion testing.


4.

Combined grading of each mix design.


5.

Specific gravity of all materials.


6.

Results of required tests.


7.

A certificate of compliance signed by the supplier identifying the type of fly ash and
stating that the fly ash is in accordance with AST
M C 618 and these specifications.
Supporting test data shall be furnished when requested by the Agency.


8.

Water/Cement Ratio vs. compressive strength test results


9.

Material specifications and instructions for Concrete Admixtures use


10.

Air content, unit wei
ght, and compressive strength test results for proposed mix design


11.

Calculations and/or manufacturer’s certifications which demonstrate and identify the
maximum placement pressures
required to complete the backfill and prevent foam
collapse.


12.

Allow at leas
t 20 working days from the date of the original submittal to the mobilization
of equipment or purchase of materials, as appropriate, to allow for review and at least
one resubmittal of each item.


Equipment:

Equipment submittals shall include:


Manufactu
rer's specifications and operation instructions for conveyance equipment


Pumps


Foam generators and ancillary equipment

City of Vista
, C.I.P. No. 807
7

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200


The Contractor shall provide the Work Plan for placing low density cellular concrete including
sequence of work, type(s) of equipment,

location of equipment, placing procedures (i.e., batching,
mixing, and pumping procedures), concrete conveyance provisions, pump line arrangement
(including moving and breaking), communications provision, methods for monitoring mix, testing
procedures, an
d cleanup procedures. The work plan shall also detail the methods and sequence of
maximizing placement of cellular concrete fill into the voids between the casing pipe and the carrier
pipe. The work plan shall include pumping pressures, pumping rates, vo
lumes to be placed per day,
injection locations, and sequence of placement and pumping.


The Contractor shall control the density of backfill material and fill PVC & HDPE carrier pipelines
with water as required to prevent floatation during backfill operat
ions. When applicable t
he
Contractor shall submit drawings showing the spacers

or restraints

being used to prevent the carrier
pipe from floatation along with certification from the carrier pipe supplier that proposed spacer
details to prevent floatation
are in accordance with their recommendations and shall not damage the
carrier pipe.


The Contractor shall s
ubmit shop drawings showing how the cellular concrete backfill will be
terminated at the ends of the tunnel.


The Contractor shall submit details a
nd testing results for cellular concrete backfill trial mixes.


The Contractor shall submit
w
ritten documentation from the Manufacturer indicating that they have
reviewed the project requirements, materials, equipment, procedures, trial mix tests, and fina
l mix
design, and approve the proposed procedures for final mixing and placement.


The Contractor shall complete backfill operations across each tunnel reach in one continuous
backfill lift, unless otherwise accepted by the Engineer.

If multiple lifts are

requested by the
Contractor, the Contractor shall include, with its request, the p
roposed method to determine the
limits of cellular concrete backfill to verify as a minimum that the invert and crown are filled and to
determine the limits of each successi
ve backfill lift.


The Contractor shall provide Test Reports and Certifications. Submittals shall include:


Mill test reports for cement


Certificates of compliance for each load of cement and Pozzolan


Certifications of compliance for all admixtures


A d
elivery ticket with the information stated in Section 16 of ASTM C 94; excluding actual
scale weights of materials shall be furnished to the Agency with each batch of concrete before
unloading at the site.


A printout of the actual scale weights for all lo
ads batched shall be submitted to the Agency at
the end of each working day.


Daily reports and records of concrete placement including, but not limited to, volumes placed,
stationing of placement, injection locations, pressures, unit weight and air conten
t testing results,
time of placement, and designation of cylinder samples prepared that day.


City of Vista
, C.I.P. No. 807
7

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201

The Contractor shall submit the control valve arrangement to the Agency for review at least 15 days
prior to commencing cellular concrete backfilling operations.


The Contractor shall submit results of Trial Mixes and Field Trials. Data shall include batch
proportions of all components, test results, and field measurements.



703
-
1.6 Quality Assurance.


Qualifications
: Qualifications shall include the following:


The Contractor shall be capable of developing a mix design, and batching, mixing, handling
and placing low
-
density cellular concrete under tunnel conditions. The Contractor shall have
furnished and placed low density cellular concrete on at least three
tunnels of the general type
and the size specified herein which have been in successful operation and shall have a record
of experience and quality of work using low density cellular concrete that is satisfactory to the
Agency.


As an alternative, the Cont
ractor may employ a manufacturer's representative to supervise
supplying and placing of cellular concrete. The manufacturer's representative shall be
capable of complying with the qualifications specified for the Contractor and shall be
acceptable to the
Agency. The manufacturer's representative shall supervise all cellular
concrete operations including training the Contractor's personnel, mixing designs, and
placement of cellular concrete in the tunnel.


The Contractor's superintendent who is responsible

for installation of cellular concrete shall
have previous experience on at least three similar previous projects under similar ground and
tunnel conditions or the cellular concrete supplying and placing shall be under the s
upervision
of the Manufacturer o
r by the Manufacturer’s approved applicant.


The Manufacturer shall provide engineering field services to review the project and the
material application prior to any preparation to approve the applicator, the material used, the
equipment, and the procedu
res to be used; to approve setup before production of cellular
concrete; and to observe during initial application. The Manufacturer shall submit, in writing,
approvals of proposed material, equipment, application procedures, applicator, and setup
before
production.


A tentative mix shall be designed and tested in accordance with ASTM C 796 for each
consistency intended for use. These results will be compared with field test results to confirm
consistent properties are obtained in the field. Preliminary
testing for each mix shall be as
follows:


Two sets of compression test cylinders (three inches by six inches), three cylinders per set,
shall be made from each proposed cellular concrete mix. One set of three cylinders shall be
tested at an age of seven
days and the other set shall be tested at an age of 28 days. Cellular
concrete test specimens shall be made, cured, stored, and tested in accordance with ASTM C
495.


Determination of total air content of each proposed cellular concrete mix in accordance
with
ASTM C 796.


City of Vista
, C.I.P. No. 807
7

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202

Determination of unit weight of each proposed cellular concrete mix in accordance with ASTM
C 567.


Field Tests
: Field tests shall comply with the following:


Field control tests, including unit weight (wet density), air content test, an
d the making of
compression test cylinders, shall be performed by the
Agency.


The frequency specified herein for each field control test is approximate. A greater or lesser
number of tests may be made, as required by the Agency.


Test specimens shall be
collected within the tunnel at or near the connection where the
cellular concrete is being injected.


A system of valves in the line transporting the cellular concrete, which will allow easy access
for collection of test specimens without disconnecting the

line from the outlet, shall be provided
at or very near the point of injection.


Unit weight (wet density) test shall be made from the first batch mixed each day, after a
change in mix design, from each batch of cellular concrete from which compression te
st
cylinders are made, and at a frequency of not less than one per hour. Unit weight shall be
determined in accordance with ASTM C 567. Unit weight at the point of placement shall be
within plus or minus five percent of the unit weight established for th
e mix design being placed.

Adjust mix as required to obtain the specified unit weight.


An air content test shall be made from the first batch mixed each day and from each batch of
cellular concrete from which concrete compression test cylinders are made.

Air content at the
point of placement shall be the difference between the wet density at the point of placement
less the wet density at the point immediately before the addition of preformed foam. Air
content shall be determined in accordance with ASTM
C 138 except there shall be no vibration
or rodding of the sample.


One set of four test cylinders (three inches by six inches) shall be made for each shift when
cellular concrete is placed. One additional set shall be made from each additional 100 cubic
yards or major fraction thereof, placed in any one shift. Two cylinders from each set shall be
compression tested at an age of 28 days; one cylinder shall be tested at an age of seven days.


Compressive strength of cellular concrete shall be considered sa
tisfactory if both of the
following requirements are met:


Average of three consecutive compressive strength tests equal or exceed the specified
unconfined compressive strength.


No individual compressive strength test (average of two cylinders) shall be b
elow the specified
unconfined compressive strength by more than 20 percent.


The 28
-
day strength test shall be the average of the compressive strengths of two cylinders
made from the same concrete sample and tested at 28 days.


Test cylinders shall be cast

in the field, cured and stored in the laboratory, and tested in
accordance with ASTM C 495.

City of Vista
, C.I.P. No. 807
7

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4002


203


Each set of compression test cylinders shall be marked or tagged with the date and time of
day the cylinders were made, the location in the work where the cellula
r concrete represented
by the cylinders was placed, batch number, wet density unit weight, and the air content.



703
-
2 PRODUCTS.

703
-
2.1 Materials.


Cement:

Conform to the requirements of ASTM C 150.


Water:

Potable water free from deleterious amount
s of alkali, acid, organic materials, or other
impurities that would adversely affect the setting time, strength, durability, or other quality of the
cellular concrete. If warm water is used to preform the foam, it shall not exceed 80 degrees
Fahrenheit (
°F).


Admixtures
: Admixtures may only be used when specifically approved by the foaming agent
supplier in writing.


Foaming Agent
: Foaming agent shall comply with ASTM C 869 when tested in Accordance with
ASTM C 796. The type and manufacturer shall be:




Mearl Geofoam Liquid Concentrate manufactured by The Mearl Corporation, Roselle Park
;

NJ.



Foam Liquid Concentrate manufactured by Cellufoam Concrete Systems



or

approved equal.



703
-
2.2 Mix Design.


Low density cellular concrete mix shall be designed in

accordance with the requirements of this
Section, ACI 523.1R, ACI 523.3R, and the additional requirements herein. Mixes shall be adjusted
in the field as necessary to meet the requirements of these specifications. The Manufacturer shall
approve all chan
ges to the mix designs.


Minimum seven
-
day and 28
-
day compressive strength (ASTM C 495) shall be 300 and 500 pounds
per square inch (psi), respectively.


Unless otherwise specified, each cellular concrete mix shall be designed and controlled within the
fol
lowing limits:


As the point of placement, the wet density unit weight of the cellular concrete shall be not less
than 50 pcf and shall be within 5 pcf plus or minus of the density of the approved cellular
concrete mix.


Preformed foam shall be generated b
y combining controlled quantities of air, water, and foaming
agent under pressure. Foam shall retain its stability until the cement sets to form a self
-
supporting
matrix. The resulting cellular concrete shall have essentially closed cell and low water ab
sorptive
characteristics. The concentration of foam agent shall be in accordance with the Manufacturer s
recommendations.


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, C.I.P. No. 807
7

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204

The admixture content, batching method, and time of introduction to the mix shall be in accordance
with the manufacturer s recommend
ations for minimum shrinkage and for compliance with these
specifications. Admixtures may be used when specifically approved by foaming agent material
manufacturer and shall be in accordance with their recommendations. No calcium chloride or
admixture co
ntaining chloride other than impurities from admixture ingredients shall be acceptable.


All proposed changes to the mix design shall be submitted to the Agency for approval prior to
implementation.



703
-
3 EXECUTION.

703
-
3.1 General Requirements.


Follo
wing placement of the carrier pipe, completely fill the annular space between the carrier pipe
and the casing pipe to maximum extent possible with cellular concrete backfill in accordance with
these specifications.


Provide the necessary means and methods
to fill voids between the casing pipe and the carrier pipe,
to the maximum extent possible.


Place low
-
density cellular concrete as specified herein. Make cellular concrete using preformed
foam process equipment approved by the Manufacturer and the Agency
.


Methods for completely filling the annular space between carrier pipe and the casing pipe shall be
subject to approval by the Manufacturer and the Agency.


Inform the Agency at least 72 hours in advance of the times and places where placement of cellula
r
concrete is anticipated.


Prior to backfill the Contractor shall e
liminate standing water where low density cellular concrete is to
be placed.


The Contractor shall complete backfill operations across each tunnel reach in one continuous
backfill lift, un
less otherwise accepted by the Engineer.



703
-
3.2 Batching and Mixing.


General Requirements
: Conform to the requirements of approved submittals and the Manufacturer
s recommendations.


Mixing:

Mixing requirements are as follows:


All cellular concrete

shall be mechanically mixed to produce a uniform distribution of the
materials with a suitable consistency and the specified limiting requirements. Excessive
mixing shall be avoided in order to reduce the possibility of changes in unit weight and
consist
ency and separation.


In batch mixing operations, follow the manufacturer's recommendations regarding the order of
charging the mixer with the various ingredients. The as
-
cast unit weight shall be monitored, as
well as the method of placement, such as mec
hanical or pneumatic pumping, and any unit
City of Vista
, C.I.P. No. 807
7

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205

weight changes that may result from these methods.


For continuous mixing operations, provision shall be made for reasonably uniform and
continuous rate of addition of all mix components at appropriate positions i
n the mixing
machine and in the correct ratio, to assure uniformity and the specified limiting requirements at
the point of placement.


Alternative methods for batching and mixing cellular
concrete shall be considered by

and must
be acceptable to the Agenc
y.



703
-
3.3 Placing Cellular Concrete.


All void space outside of the carrier pipe shall be completely filled with low
-
density cellular concrete.

Force cellular concrete into all irregularities around the tunnel to completely fill the tunnel arch
crown
and annulus with low
-
density cellular concrete to the maximum extent possible. Place cellular
concrete in accordance with approved submittals.


Use vertical construction joints at bulkheads unless approved otherwise by the Agency.


At the start of cellula
r concrete backfilling operations, extend the discharge pipe from the placing
equipment to the point of lowest elevation of the section of tunnel being backfilled.


A high
-
end vent is required and shall rise at least 2 feet above the casing crown and not m
ore than 3

feet. The vent shall overflow at least 1 cubic yard.


Backfilling of the annular space between the carrier pipe and the casing pipe
may
be accomplished
by placing cellular concrete in multiple lifts. Monolithic placements shall be acceptable,
provided the
Contractor can demonstrate that the placement techniques shall not induce movement or
deformation of the carrier pipe.

In no case shall the maximum depth of grout installed per day
exceed 36
-
inches of maximum height or the maximum height calcu
lated to prevent collapse of the
foam.


Pressure gauges of appropriate range for monitoring the low
-
density cellular concrete injection
pressures shall be located in the line transporting the cellular concrete at the point of injection.
Pressure shall no
t exceed 15 psi at the point of injection unless lower pressures are required to
prevent movement or deformation of the carrier pipe

or to prevent a collapse of the foam
.


Volume of cellular concrete injected shall be measured, recorded, and compared with
the
anticipated volume per foot of tunnel backfilled.


Sample are to be taken at the point of injection.


Provide a means of direct communication between the injection point and the pump operator.



703
-
3.4 Protection and Clean
-
Up.


Take all necessary pre
cautions to protect and preserve the carrier pipe from damage. Spills shall be

minimized and shall be cleaned up immediately. Any damage to the carrier pipe caused by, or
occurring during, the backfilling operations shall be repaired by a method approved

by the Agency at
City of Vista
, C.I.P. No. 807
7

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4002


206

no additional cost to the Agency.


During backfilling work, provide for adequate disposal of all wastes. Minimize cellular concrete spills
and clean up immediately after backfilling. Remove and properly dispose of all waste resulting fr
om
backfilling operations.



SECTION 704


INSTRUMENTATION AND MONITORING


704
-
1 GENERAL.

704
-
1.1 Scope.


This Section specifies the requirements for installing
settlement monuments

to monitor ground and
structural movements during shaft and tunnel excav
ation. The Work shall include furnishing,
maintaining, monitoring and removing all
mounments
associated with the construction work shown
in the Drawings and as necessary to safely complete the Work.



704
-
1.2 Submittals


Contractor shall submit the follo
wing items:


Proposed schedule for installation of survey control points as required per this spec section.


Description of the survey control point installation procedure as required per this spec section.


Detailed drawings indicating the layout and des
ignation of all ground surface survey control
points required per this spec section.


Description of the proposed methods for monitoring the survey control points required per this
spec section.


Reports of Surface Monitoring Point data to the Agency withi
n four hours after data collection
.




704
-
1.3 Qualifications


Qualifications for Surveyor
: Contractor shall employ a Land Surveyor licensed in the State of
California with experience surveying for the detection of structural or surface deformations to
i
mplement the requirements of this section.



704
-
1.4 Quality Assurance


Installation
: Provide notice to the Agency not less than one working day before
settlement
monument
installation. Label all
monuments
with an identifying
monument
number.


Installat
ion Tolerances
: Install Surface Monitoring Points within two degrees of vertical for the entire
length of the casing.


Should actual field conditions prevent installation of
monuments
at the location and elevations
City of Vista
, C.I.P. No. 807
7

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4002


207

specified herein, obtain prior acceptanc
e from the Agency for new
monument
location
s.



Subsurface Information
: Contractor shall refer to the subsurface information which is
detailed in
Appendix C


Geotechnical Investigation.



704
-
2 PRODUCTS

704
-
2.1 Materials


Sand:

Shall conform to ASTM C
778 for 20
-
40 sand.


Cement Grout
: Shall be Type II Portland cement and water in accordance with ASTM C 150.



704
-
2.2 Surface Monitoring Points


Where the ground surface consists of sidewalk, street, railroad, or vegetation, the Surface
Monitoring Point
s shall consist of a grouted re
-
bar anchor inside a casing. The top, flush with the
ground surface, shall be protected to prevent personal injury or damage to the device. A drill rig
shall drill vertically a 6
-
inch hole, approximately four feet deep. Th
e top 6 inches of the hole shall be
cased to protect the instrument. A four
-
foot long 4
-
inch diameter casing shall be installed vertically
in the hole and the annular space grouted. The grout shall be weaker than the soil that was
removed. A #8 re
-
bar,
approximately 5 feet long, shall be installed with one foot buried in the
ground below the bottom of the hole. The Contractor shall ensure the functionality of the instrument
to measure subsidence.


Where a vertical object rises more than 6 feet above the

ground surface, and is within 25 feet of the
tunnel centerline, the survey shall include three
-
dimensional documentation of the vertical nature of
the object.


The Surface Monitoring Points shall be surveyed following installation, with a second survey
co
mpleted before commencing tunneling. The second survey shall not be started until all Surface
Monitoring Points have been installed and the first survey completed by at least one working day.



704
-
3 EXECUTION

704
-
3.1 General


Provide the Agency access
to
monument
locations and provide Agency with Contractor
-
collected
monitoring data.


Perform subsidence monitoring as described herein.


The
monumentation
specified is the minimum required. The Contractor shall install additional
surface monitoring points

as necessary to control the work and provide a safe working environment,
and shall do so at no additional cost to Agency.


Contractor shall install
surface monitoring points
at the locations specified, or as directed or
approved by the Agency a minimum of

seven calendar days prior to start of shaft excavation unless
otherwise specifically stated in the specifications.


City of Vista
, C.I.P. No. 807
7

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4002


208

Locate conduits and underground utilities in all areas where subsurface geotechnical
instrumentation is to be drilled and installed. Repai
r damage to existing utilities resulting from
surface monument
installations at no additional cost to the Agency.


Monument
holes shall be subject to the same permitting and drilling requirements as those for
geotechnical exploration boreholes. Contractor

shall obtain necessary permits for each such
instrument and conform to the permit requirements during drilling, installation, monitoring, and
abandonment. Conduct drilling operations using appropriate methods that are consistent with
geologic conditions
presented
in
Appendix C


Geotechnical Investigation
.



704
-
3.2 Surface Monitoring Points


Establish a grid of Surface Monitoring Points on the ground surface for the purpose of monitoring
ground subsidence resulting from tunnel excavations as required by
the Agency and as specified
herein.


Establish Surface Monitoring Point arrays oriented perpendicular to the tunnel centerline at
approximately
200
-
foot intervals

with the first and last array within 50 feet of each shaft.


A minimum
of three arrays shall
be installed for each tunnel reach.

Each array shall consist of three control
points: one on the tunnel centerline; and two 7
-
feet either side of tunnel centerline. Review Surface
Monitoring Point locations in the field during construction with the Agency

and modify locations if
required.


Provide up to 10 additional Surface Monitoring Points at locations to be determined in the field by
the Agency, at no additional cost to Agency.


Determine the elevation of each Surface Monitoring Point to an accuracy

of
+

0.01 foot.


Determine the elevation of each control point prior to commencing tunnel excavation and survey
each control point at 2
-
working day intervals following commencement of tunnel excavation.


Continue taking survey readings weekly for a peri
od of two months following completion of tunnel
excavation, or as directed by the Agency.



704
-
3.3 Instrumentation and Monitoring


Contractor shall carry out operations to minimize settlement and/or heave of the ground. Repair, at
Contractor's sole cos
t, all damage due to settlement, consolidation or heave from any construction
induced activities.


Contractor shall submit a settlement surveying and monitoring plan with a contingency plan if
settlement or heave reach
es

the prescribed Response Values, f
or review prior to construction. The
plan shall identify the location of all instruments and survey points, reference benchmarks, survey
schedules and procedures and reporting formats.


Submit, for the Agency's review prior to construction, a Building and

Structures Assessment Plan.
Provide pre
-
construction and post
-
construction assessment reports for buildings and structures
located within a distance of 50 feet from the proposed pipe centerline and shafts. Include
photographs or a video of any existing
damage to structures in the vicinity of the sewer alignment in
City of Vista
, C.I.P. No. 807
7

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4002


209

the assessment reports.


Add inclinometers for each shaft that has a sensitive structure (2 locations with houses next to a
shaft) and where the loads are unbalance
d

on opposite sides (4 locati
ons).


Add utility settlement points for utilities within 25 feet of a shaft or where there is less than 6 feet of
separation between the existing utility and the new installation.


In the event of movement of the ground surface, structure or utility being

detected or damage
recorded, the Agency may order that the Work be stopped and secured. Before proceeding,
Contractor shall correct any problems causing or resulting from such movement entirely at no
additional cost to the Agency. If ground settlement o
r heave occurs
,

which might affect the accuracy
of temporary or permanent benchmarks, monitor and immediately report such movement to the
Agency.



704
-
3.4 Survey


Contractor shall adhere to the following requirements concerning survey oversight:


Initial

Survey:

Record the horizontal coordinates and elevations (with accuracy of 0.01 feet) for each
survey point location. Reference survey points so that they may be accurately re
-
established if lost
or destroyed.


Interim Surveys:

Take readings at least o
nce per week unless otherwise required. Report on
readings from the various instruments and survey points to the Agency on the same day the
readings are taken. Commence readings at the commencement of shaft sinking. Take initial
readings one week before

any other excavation or construction is started. Continue to monitor
weekly and for at least 4 weeks after completion of any tunnel section.


Final Survey:

At the end of all construction operations, make a final survey of all control points
established

for instrumentation and observation. Submit final readings to the Agency upon
completion of the survey.



704
-
3.
5

Monitoring


Initial Readings
: The Contractor shall take initial readings of all
settlement monuments
to establish
a baseline and provide
the Agency with these data.


Frequency:

The Contractor shall monitor required instrumentation and provide the Agency with
these data. As a minimum, the Contractor shall use the following schedule:


Instrument Type

Active Zone

w楴h楮‱MM ft

of phaft bxcav
at楯i


or qunne氠bxcavat楯i

併ts楤i Act楶e wone

purface jon楴or楮i mo楮瑳

bvery O tork楮i aays

teek汹/jonth汹
1


oeport楮i:

qhe Contractor's sub浩mted data sha汬 楮i汵leI but are not 汩浩med toI the fo汬ow楮i:

††††††††††††††††††††
††††

1

Weekly until movement substantially stops and monthly thereafter
.

City of Vista
, C.I.P. No. 807
7

Dwg. No.
4002


210


Data sheets containing a cumulative hist
ory of readings, including weather conditions and proximity
of the excavation to the instrument location at the time of each reading.


A plot of measured values versus time, including a time history of construction activity likely to
influence such reading
s.


Interpretation:

The Contractor shall create interpretations of monitoring data for the Contractor's
purposes. Data or interpretations shall not be published or disclosed to other parties without
advance written permission of the Agency. The Agency m
ay provide the Agency's interpretations of
the data to the Contractor at the Agency's option.


Final Disposition
: In accordance with California Department of Water Resources "California
Well
Standards


Bulletin 74
-
90
"
,

Contractor shall destroy all Instrum
entation Boreholes as required for
construction of the Work. Contractor also shall submit documentation to the Agency for review prior
to submission to the local permitting agency.


The Contractor also shall adhere to the following requirements:


Surface
Monitoring Points:

Remove all
monumentation
during the cleanup and restoration work or
as required by the Agency.



704
-
3.
6

Resp
o
nse Values


Response Values are a percentage of

the Maximum Allowable Movement.

The movement may be
either plus or minus. P
lus movement is defined as “heave” and minus movement is defined as
“settlement”.


The “Threshold Value” is 60% of the maximum allowable movement.


The “Contractor Response Value” is 80% of the maximum allowable movement.


The “Shutdown Valve” is 100% of

the maximum allowable movement.


The Contractor shall abide by the following Response Values:



Maximum Allowable Movement +/
-

Instrument Type

AC Water

Agency

Utility

Surface Monitoring Point

0.00 inch

1.00
i
nch

0.50 inch



When a giv
en response value is reached, the Contractor shall respond in accordance with the
following:


Threshold Value
. The Contractor shall meet with the Agency to discuss his means and method to
determine what changes, if any, shall be made to better control gro
und movement.
Monument
readings shall be required on a daily basis until five consecutive working days of readings below the
Threshold Value.


Contractor Response Value
. The Contractor shall actively control ground movement in accordance
City of Vista
, C.I.P. No. 807
7

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4002


211

with the approv
ed plan to prevent reaching the Shutdown Value.

Monument r
eadings shall be
required on a daily basis until five consecutive working days of readings below the Threshold Value.


Shutdown Value
. Contractor shall stop all Work immediately. The Contractor s
hall meet with the
Agency to develop a plan of action before the Work can be resumed.



704
-
3.
7

Restoration of Existing Facilities


Contractor shall restore all facilities to like condition before resuming work at no additional cost to
Agency.


City of Vista
, C.I.P. No. 807
7

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4002


212












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