inspection of pressure lines and culverts · conditions of pressure waste-water conduits, the...
TRANSCRIPT
Inspection
inspection of pressure lines and culverts
The IKT has now completed the first project phase on “Inspection and state-registration of pressure waste-water lines and culverts”. The aim of this initial phase was that of obtaining information on the general inspectability of such conduits using the available technology, on the preconditions for use and usability of the various inspec-tion methods, and on the necessary cost and labour inputs.
Results publishedThe German version of the detailed concluding report for the first project phase [1], and also an abridged version, are available for download on the Internet at: www.ikt.de
Pumping stations and waste-water pressure lines are frequent features of drain and sewer systems. They are used in sectors of these sys-tems in which it is possible to implement drain-age by means of gravity lines only with technical difficulty and/or at high cost. This is the case, in particular, where natural topographical gra-dients are lacking, where waste-water occurs only in small amounts and/or only periodically (due, for example, to low population densities), in case of the necessity of overcoming obstruc-tions and in case of unfavourable underground circumstances as a result, for instance, of the presence of rock or of high groundwater tables.
In the German Federal State of North Rhine-Westphalia (NRW), some 90% of all drain/sewer operators (357 of a total of 396) operate pressure waste-water pipelines [2]. The total length of pressure waste-water pipes in the state is no less than 3,491 km, thus equating to just on 4% of the total public waste-water conduit system [2].
Waste-water culverts are among the “cross-ing elements” necessary when the course of pipelines encounters obstacles, such as rivers, for example. A total of 1,278 waste-water culverts are operated and maintained [2] by the 396 municipal waste-water system operators and eleven water boards in North Rhine-Westphalia. A survey of 208 system operators in NRW per-formed by IKT indicated that 131 (63%) of the operators polled have one or more culverts [3].
Assurance of permanent good functioning is par-ticularly important in the case of pressure lines and culverts. Blockages and resultant flooding (and thus hazards for the groundwater and for main drains), and also damage to connected property, may be the consequence if a pres-sure line or a pumping station fails, or if flow through a culvert becomes obstructed. Leaking conduits can result in waste-water escaping into
Searching for a pressure pipeline
Course of a culvert underneath the Rhine-Herne Canal in Oberhausen; head and tail gate
the groundwater and/or soil, and may cause cavitation in the surrounding soil, with the result that harm to the surface cannot be excluded.
The (visual) assessment of condition is one of the customary operational tasks in the field of grav-ity drains and sewers. The situation is different in the case of pressure conduits. Maintenance and inspection activities are generally restricted to pumping stations and the venting valves of the conduits. Inspections are generally not scheduled during the operating period of these lines, and they are classified as “maintenance-free” under DWA (German Association for Water, Wastewa-ter and Waste) Code 116-2 [4]. Numerous system operators are nonetheless confronted with the question of the condition of their pipelines, par-ticularly if operational problems have already occurred. A decision as to whether a conduit should continue in operation, in order to utilise possibly still existing reserves of service-life, and thus save costs, or whether the conduit should be renewed or refurbished, will need to be taken, at the latest, toward the end of the scheduled period of service. This, however, is a decision which can scarcely be made without knowledge of the condition of the conduit.
35 IKT
Inspection
the conduits using the available technology, on the preconditions for use and general suitability for use of the inspection methods, and on the necessary financial and labour input, in order to permit derivation of initial recommendations for action concerning the inspection and appraisal of the condition of pressure waste-water conduits.
The operators‘ operating experienceAs a survey of the participating system operators concerning measures for appraisal of the condi-tion of pressure waste-water conduits illustrated, inspection and maintenance activities currently relate predominantly to pumping stations, valves, etc., and to venting stations. Pressure conduits in these systems had been tested for tightness by means of hydraulic pressure testing only in individual cases, or part-sections of conduits camera-inspected, generally in conjunction with operational problems and repairs.
On the basis of the experience of the steering committee, a large number of existing pressure conduits can continue to be operated without problems occurring and without any cleaning and/or inspection activities. The precondition for this is that the conduits were constructed in accordance with the requirements and have not, for example, proven to be overdimensioned, and that flow velocity does not fall below the speci-fied minimum. Odour problems associated with pressure waste-water conduits do appear to be problematical for the overwhelming majority of operators, however. Such odour problems gener-ally occur at the outlet from pressure conduits as a result of emissions of hydrogen sulphide, which
Provisions for the assessment of condition are necessary to permit appraisal of the state of pressure pipelines. Access ports are either pre-sent only at great intervals, if at all, however, since inspections of pressure lines during opera-tion are generally not envisaged at the original planning stage. In addition, the conditions for inspection are made more difficult by bends, partial or complete filling of the conduits, and rising and falling gradients. Many system opera-tors are therefore uncertain of the extent to which inspections and/or appraisals of condition are possible, and concerning the methods avail-able for these activities.
The recently completed project was commis-sioned by the NRW environment ministry against the background of the fact that experience in the assessment of the condition of pressure waste-water conduits is virtually totally lacking.
The initial project phase was supported in terms of content by a steering committee featuring the representatives of twenty-seven system operators. Research was firstly conducted into the methods available on the market for condi-tion assessment; the civil-engineering boundary conditions of pressure waste-water conduits, the operating experience of the participating system operators and the various types and forms of damage were compiled in parallel. Test deploy-ments of selected methods on existing pressure conduits owned by the operators were then conducted by way of example. The objective of this first project phase was that of obtaining information on the general “inspectability” of
is evolved in waste-water in the absence of oxy-gen after prolonged periods of immobilisation.
Declining pump delivery heads and rates, depo-sitions, grease fouling of venting valves, valve corrosion and also, in isolated cases, damage to the conduit and/or blockages causing operation-al failures, were stated as problems occurring in the operation of pressure waste-water conduits.
When operational problems occur, the conduits approach their design service-life limit and/or greater operational reliability is desired in the case of large transmission pipelines, failure of which would cause serious consequences, sys-tem operators are frequently confronted with the question of how to determine and evaluate the condition of their conduits.
These conduits must, in principle, be replaced upon the expiry of their design service-life, in order to keep the likelihood of operational prob-lems caused by damage to a pressure conduit as low as possible. A number of operators do in fact adopt this procedure. Others continue to operate conduits which have up to now not exhibited any problems beyond the design service-life, in order thus to save costs but at the risk of incurring unforeseeable operational problems. The KVR (Ruhr Regional Alliance) guidelines [5] for pres-sure pipe and culvert lines state an average oper-ational service-life of 30 to 50 years, irrespective of their material. DWA Code 116-2 [4] states a figure of 50 to 80 years. The assumptions made by the operators are diverse, with periods of 40 to 80 years mentioned as scheduled service-lives.
36IKT
By way of preparation for possible test deploy-ments, operators who had proposed test sections from their own systems compiled the information available on their conduits. An evaluation dem-onstrated that only little data on the pressure conduits usually existed, and that in many cases neither the precise course of a conduit, nor the location and nature of bends were known. It did, it is true, prove possible to provide plans in most cases, but these contained information and data which largely failed to reflect the actual circum-stances, while it was possible to estimate the location and gradient profile of the conduits only using known reference points, such as manholes and venting valves.
Types and forms of damageA catalogue of types and forms of damage to pressure waste-water conduits was compiled in the context of a survey of the participating system operators. Evaluation demonstrated that only few damage patterns of informational value are available at present. Inspections, which could provide information on damage patterns, are not customary practice. Damage is therefore frequently only noticed when significant defects which restrict operation of the line occur, such as a ruptured conduit, for example. Such dam-age then necessitates immediate repair of the conduit, however. Further information obtained from the literature concerning types of damage
occurring in drinking-water conduits consisting of similar materials was therefore used in order to expand the data-base, with the result that an initial overview of possible damage types is available for pressure waste-water conduits.A summary of the various types of damage can be found in the concluding report [1].
Methods for determination of conditionNumerous methods for determination of the con-dition of pressure conduits are available on the market. These, however, have mainly been devel-oped specifically for inspection of oil and/or gas pipelines, or of community-heating and water sup-ply pipes and industrial piping systems. They are therefore generally orientated around steel as the pipe material, and around the common DNs, access facilities and bends encountered in such systems.
An overview of methods which can be considered in principle for determination of the condition of pressure waste-water conduits, and of their func-tioning principles, preconditions for use and costs, was drafted as part of this project. Commercially available technologies which have already proven their basic suitability for use in the context of waste-water drains/sewers and/or supply and industrial pressure conduits were primarily includ-ed in this overview:
Internal inspection methods In-conduit cameras and add-on modules Inspection robots Inspection pigs Float-in and drawn inspection methods
External inspection methods Inspections of exposed pipe wall Inspections of soil-covered pipes
Hydraulic pressure testing
Tests performed on material samples
Cracking at a flanged joint in a PVC pressure waste-water pipe at the pumping station (photo: Emmerich/Rhine municipal services)
Swollen asbestos-cement pipe in a pressure waste-water conduit (photo: Eastern Holstein municipal alliance)
Pitting corrosion in a grey cast iron pressure waste-water conduit (photo: Nuremberg Municipal Drainage and Environmental Analysis Services)
Ovality caused by point load in an HDPE pressure waste-water conduit (photo: Emmerich/Rhine municipal services)
Deformation caused by point load in an HDPE pressure waste-water conduit (photo: Emmerich/Rhine municipal services)
Section from a corroded asbestos-cement pipe in a pressure waste-water conduit (photo Emmerich/Rhine municipal services)
graphitised cast iron drinking-water pipe (photo: H.-C. Sorge)
37 IKT
Inspection
condition. Where determination of the condition of a pressure conduit is required, it is necessary to select appropriate procedures on the basis of civil-engineering boundary conditions such as material, DN, type and distances between access facilities, potentials for evacuation, the type and number of bends, and of the pressure conditions and inspection target, such as obtain-ment of information on tightness and/or corro-sion, etc., and to combine these technologies correspondingly.
An appropriate procedure on cost:benefit criteria would be to firstly test conduits for tightness by means of a hydraulic pressure test and then per-form TV inspections on accessible conduits sec-tors, and also to record operational data, such as delivery flows, power take-up at the pump and pressure at the pumping station.
The work, etc., input necessary for hydraulic pressure tests varies depending on the facilities for sector isolation, the elevation profile and the potentials for venting of the particular conduit. Pressure conduits which rise continuously from the pumping station, and which are (almost) completed filled, can be tested comparatively easily. Such testing will be more difficult in the case of conduits with high and low points, and also gradients which empty toward the end of the conduit. Here, filling is more complicated, and high points with no venting facility mean that pockets of air may occur in the conduit and falsify the test. Where great elevation differenc-es exist, it may be necessary to isolate individual sectors for testing.
Despite the fact that DIN EN 1610 [6] draws attention to DIN EN 805 [7] for acceptance
Research on inspection methods, talks with manufacturers and practical deployments performed by way of example all illustrated that there is, at present, no “ideal” technology available on the market, using which inspections could be performed simply and cost-efficiently, as in the case of gravity conduits, and which would, in addition, supply adequate information on the condition of the conduit. Pressure waste-water conduits present more difficult boundary conditions than gravity conduits, due to the rarity or complete absence of access facilities, complete filling of the conduits, or at least of sections thereof, due to bends and, in addition, due to the in many cases not precisely known courses of the conduits and to the in some cases small nominal diameters (DNs).
It can be assumed that it will be possible to investigate the condition of many conduits only by means of a combination of various inspection methods, and with preparatory civil-engineering modifications involving a high technical and financial input. Conduits of diameters of 150/200 mm and above appear to be relatively easily inspectable, whereas the potentials are significantly poorer in the case of smaller diam-eters. The extent to which the necessary input is rational in each individual case will essentially depend on the operational importance of the individual conduit, and the hazard potentials its failure would present.
It remains, overall, to be ascertained that there are, up to now, no technologies available on the market which can, in general, be used for pressure waste-water conduits and/or culverts and which, simultaneously, will supply compre-hensive information for evaluation of conduit
inspection of pressure waste-water conduits, it should, nonetheless, be noted that this standard was, in principle, drafted for drinking-water conduits. The degree to which the respective detailed provisions can actually be applied to the situation in the waste-water sector must therefore be continuously assessed. The rea-sons for this are that, on the one hand, it is in many cases not possible to adhere to the civil-engineering boundary conditions assumed in DIN EN 805 in terms, for example, of acces-sibility, venting and isolation during the test. In addition, there are, on the other hand, no test criteria/limiting values for evaluation of the test result for tightness testing, since the hazard potentials relevant to the waste-water sector were not taken into account in EN 805. The question also arises of the extent to which the test pressures specified for acceptance inspec-tion of new conduits are also in fact appropriate for tightness testing during ongoing conduit operation. Lower test pressures are specified in ATV-M 143, Part 6 [8] for tests performed on gravity lines than are required for acceptance testing of new conduits in accordance with DWA A 139 [9].
Where a pressure test supplies indications of leaks, the question arises of the conduit compo-nents on which the leaks are located. Leak detec-tion using helium appears highly promising for this purpose. According to the supplier, dissolved helium is pumped with water through the con-duit and then enters the soil via any leaks, and is detected using detectors at the surface. It has not yet been possible to observe any practical deployments of this method in the context of the project, however. The extent to which leak detec-tion would also be possible using hydrophones,
Blistering Blistering Detachment of material on the pipe wall of an asbestos-cement drinking-water conduit (photo: M.J. Oomen BV)
38IKT
which register the typical sounds of escaping water, and can, for example, be floated in a ball through the conduit, or conveyed on a pig, is also questionable. Leaks in a long-distance drink-ing-water pipeline were detected in a monitored practical deployment of the SmartBall®, but the experience of the Water Research Centre (WRc, Swindon, UK) indicated that leaks in pressure waste-water conduits remain undetected if they have become covered with fouling.
TV inspections are possible, at least on a dis-tributed pattern at accessible points, in order to obtain approximate reference data concerning conduit condition. High points possibly featuring air pockets, in which corrosion can occur in the case of asbestos cement and cast-iron pressure conduits, in particular, are sites predestined for such inspections. It must be noted that purely visual inspection is of only limited informational value in the case of precisely these conduit mate-rials, however, since not all types of corrosion and/or material abnormalities are visually per-ceptible. Inspection of the course of the conduit as a whole is possible only rarely without struc-tural changes in pressure conduits, due to lack of accessibility, frequently restricted facilities for evacuation, and bends in the course of the con-duit. Optical inspection using a tractor camera is, in any case, significantly more complex than in a gravity conduit, since it is necessary to stop operation of the conduits and drain them.
The “towed video camera”, an axial camera with a suction-mount screen for nominal diameters of between DN 50 and DN 250, is drawn into a pressure conduit by means of a partial vacuum, and proved to be a technology well suited to pressure waste-water conduits. Experience gained in practical deployments appears to indi-cate that it is realistic to assume inspection of up to 750 m of conduit in a single operation using this method, depending on nominal diameter and bends. The camera proved to be extremely capable of negotiating bends. Friction between the pipe wall and the cable naturally becomes higher, the more bends a conduit features, reducing actual range as a result. An estimate should be made in advance to determine wheth-er evacuated pressure conduits will withstand a partial vacuum of up to 0.8 bar, i.e., a uniform external overpressure of the same magnitude. As in the case of the customarily used tractor cameras, it is necessary to ascertain the extent to which the types of damage relevant to the particular pipe material are visually perceptible.
propulsion unit
measuring unit
Advertisement
Towed video camera – an axial camera with suction-mount screen
Inspection robot featuring eddy-current inspection unit for internal inspections
Radar antenna on a camera tractor
39 IKT
Inspection
It may be possible to use sewer radar for deter-mination of the thickness of the remaining intact pipe wall in the case of asbestos-cement con-duits. Potential uses are correspondingly limited by the fact that the sewer radar is conveyed through the conduit in combination with a trac-tor camera. It is also possible to determine the pH of the pipe wall by means of a phenolphtha-lein test on pipe specimens, in order to obtain information on any material abnormalities. The precondition for this is that the conduit can be exposed and a pipe specimen taken, however.
Electromagnetic methods can be used, where possible, for examination of cast-iron conduits for corrosion. The primary operation currently practicable is the external examination of a con-duit, after its exposure. Pigs and robots incorpo-rating such technology are also available; these are currently suitable for use in pressure waste-water conduits only in individual cases, however, due to the high costs involved and the lack of explosion-protection provisions. According to information from manufacturers, the prototype of a robot incorporating electromagnetic inspec-tion technology, and to be tailored to the needs of pressure waste-water conduits, is currently undergoing testing. In addition, pipe specimens can also be taken and analysed in the laboratory for corrosion and other materials properties.
Instruments for measurement of deformation and/or cross-section are of interest for inspec-tion of flexible pipes, for example, and in the context of preparations for refurbishing projects. Here, inspection using a calibration pig is, for instance, conceivable; it must be ensured in advance, however, that the conduits do not include any bend radii of less than 1.5xD or other obstructions such as major fouling depos-its, for example. The laser light ring methods used in the gravity-line sector have, up to now, not featured explosion-safety provisions, and can therefore not be used with assured safety. Mechanical measuring systems which are con-veyed through the conduit by means, for exam-ple, of a rope winch or a flushing hose, are also suitable for use only to a limited degree, due to these systems‘ restricted bend capability and/or the lack of suitable access to the conduit.
Inspection employing smart pigs derived from pipeline technology is conceivable for steel, and possibly also for cast-iron conduits (electromag-netic technology), and can, in the manufacturers‘ opinion, possibly also be adapted for inspection of PE and PVC systems (ultrasonics). These machines are suitable for the waste-water sector only in exceptional cases, however, as a result of their high mobilisation costs.
It must be remembered, in the case of random-sampling examination of a conduit, that conclusions concerning overall condition are permissible only to a limited extent. The dam-aged pipe elements obtained during repairs should in all cases be kept and further analysed if appropriate.
As became apparent during this project, the precise course of pressure lines is in many cases not known. Location methods are therefore the first necessity in conjunction with leak detection and/or with the refurbishing or replacement of the conduit along the same route. Here, bend-capable foamed-plastic (“polly”) pigs carrying locating transmitters, and possibly also ground-
penetrating radar (GPR) methods, can be used, depending on factors such as installation depth, conduit material and conduit overcover (and also other factors, such as soil type, and salt and water contents). The use of pigs bearing measuring systems for determination of location is also conceivable, always assuming adequate bend-capability.
The most important preconditions for the use of the inspection technologies examined here, and approximate cost horizons for inspection ser-vices, are compiled in the following tables in the form of an evaluation matrix; an initial estima-tion of applicability to pressure waste-water con-duits and culverts is also provided. These tables can be used as an aid to preliminary selection of an inspection method suitable for determination of the condition of a pressure waste-water con-duit. Detailed discussions of functional principles, applications and preconditions for use of these technologies can be found in the full version of the report, available at: www.ikt.de (German version)
40IKT
Table
1: In
tern
al-in
spect
ion m
ethods:
Sew
er
cam
era
s and a
dd-o
n m
odule
s – P
reco
nditi
ons
for
use
and a
pplic
abili
ty in
pre
ssure
wast
e-w
ater
conduits
and c
ulv
erts
Meth
od
In
sp
ecti
on
aim
1
Co
nd
uit
mate
ria
l
an
d n
om
inal d
iam
ete
rs1
Mo
st
imp
ort
an
t p
reco
nd
itio
ns f
or
use
2
Co
st
rate
s,
exam
ple
s3
Su
itab
ilit
y fo
r u
se i
n
pre
ssu
re w
aste
-wate
r co
nd
uit
s a
nd
cu
lvert
s4
see f
ull
vers
ion,
Sect
ion
Sew
er
ca
me
ras
an
d a
dd
-on
mo
du
les
Tra
cto
r cam
era
O
pti
ca
l in
sp
ec
tio
n
• N
ot
ma
teri
al-d
epe
nde
nt
• A
s fr
om D
N 1
00,
fr
eq
uen
tly b
end
-ca
pab
le
on
ly f
rom
DN
12
5/1
50
on
wa
rd
• In
spe
ctio
n p
ort
s in
cou
rse
of c
on
du
it
• P
ort
spa
cin
gs d
epe
nde
nt o
n b
en
ds,
nom
ina
l d
iam
ete
r, s
urf
ace
con
diti
on,
etc
. (f
rom
a fe
w m
etr
es
to s
eve
ral h
un
dre
d m
etr
es)
• S
hu
t-d
ow
n a
nd
dra
ina
ge o
f the
con
du
it
• a
pp
rox.
80
0 €
/d
• D
aily
ave
rag
e p
ract
ical
d
ep
loym
en
ts:
35
-17
5 m
/h
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• S
uita
ble
for
rand
om
insp
ectio
n o
f ac
cess
ible
zo
nes
, in
pa
rtic
ula
r
• In
spe
ctio
n f
req
uen
tly p
oss
ible
on
ly in
su
b-s
ecto
rs (
ina
deq
ua
te a
cces
s, b
en
ds)
Cu
lve
rts
:
• S
uita
ble
for
pa
rtia
l or
com
ple
te in
spe
ctio
n,
de
pe
ndin
g o
n cu
lve
rt b
end
s, g
rad
ient
s, le
ngth
, etc
.
Ge
ne
ral:
• In
spe
ctio
n le
ngt
hs
rest
rict
ed
by
con
dui
t be
nds
, g
rad
ien
ts,
etc
.;
exp
eri
en
ce in
dic
ate
s si
gnifi
cant
ly le
ss t
han
the
tra
cto
r's m
axi
mu
m r
an
ge
(ma
xim
um
insp
ect
ion
leng
th s
yste
m-d
ep
end
en
t: 2
00 t
o 1
,000
m)
• In
form
atio
na
l va
lue
of
optic
al i
nsp
ectio
n r
estr
icte
d
4.1
.1.1
Ax
ial
cam
era
wit
h
su
cti
on
-mo
un
t scre
en
Op
tic
al
ins
pe
cti
on
• N
ot
ma
teri
al-d
epe
nde
nt
• D
N 5
0 –
DN
250
• A
cces
s a
t sta
rt a
nd
en
d o
f co
ndu
it
• In
spe
ctio
n p
ort
s in
cou
rse
of c
on
du
it
in c
on
dui
ts >
1,0
00
to 1
,50
0 m
in le
ng
th
• S
hu
t-d
ow
n a
nd
dra
ina
ge o
f the
con
du
it
• P
oss
ibili
ty o
f co
nne
ctin
g a
su
ctio
n v
eh
icle
to
the
co
ndu
it
• M
axi
mu
m h
eig
ht
diff
ere
nce
in c
on
duit:
8 t
o 9
m
• a
pp
rox.
1,4
00
€/d
• D
aily
ave
rag
e p
ract
ical
d
ep
loym
en
ts:
60
m/h
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• S
yste
m ta
ilore
d to
pre
ssu
re w
ast
e-w
ate
r co
ndu
its,
with
goo
d b
en
d c
apa
bili
ty
• R
an
ge
res
tric
ted
to
ma
x. 5
00
m (
DN
50
) to
750
m (
DN
25
0);
a
ctua
l ran
ge
de
pen
den
t on
num
be
r o
f b
ends
• C
ap
ab
ility
of c
ond
uit
to w
ithst
and
pa
rtia
l va
cuum
of
app
rox.
0.8
ba
r m
ust
be
de
term
ined
Cu
lve
rts
:
• D
ep
loym
ent
con
ceiv
abl
e o
nly
in in
divi
du
al c
ase
s
Ge
ne
ral:
• In
form
atio
na
l va
lue
of
optic
al i
nsp
ectio
n r
estr
icte
d
4.1
.1.2
Sew
er
rad
ar
• R
es
idu
al w
all
thic
kn
ess
an
d b
ed
din
g
an
om
alie
s in
asb
esto
s ce
me
nt,
con
cret
e,
PV
C,
GR
P,
sto
ne
wa
re
• T
hic
kn
es
s o
f c
eme
nt-
mo
rta
r li
nin
g
in c
ast
-iro
n a
nd
ste
el
• A
s fr
om D
N 2
00
• In
spe
ctio
n p
ort
s (s
ee "
Tra
cto
r ca
me
ra")
• S
hu
t-d
ow
n a
nd
com
ple
te d
rain
ag
e o
f th
e co
nd
uit
• K
no
wle
dg
e o
f orig
inal
wa
ll th
ickn
ess/
coa
ting
thic
knes
s (s
amp
ling/
mea
sure
me
nt i
f ne
cess
ary
)
• a
pp
rox.
2,5
00
-3
,00
0 €
/d n
ot
incl
ud
ing
tra
cto
r
• a
pp
rox.
3,5
00
-4
,00
0 €
/d n
ot
incl
ud
ing
tra
cto
r
Ge
ne
ral:
• M
eth
od
of
inte
rest
fo
r n
on
-de
stru
ctiv
e in
spe
ctio
n o
f th
e p
ipe
wa
ll in
asb
esto
s-ce
me
nt
con
duits
, in
pa
rtic
ula
r
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• S
uita
ble
prim
ari
ly f
or
ran
dom
insp
ectio
n, d
ue
to li
mite
d r
an
ge
(se
e "
Tra
cto
r ca
me
ra")
Cu
lve
rts
:
• S
uita
ble
for
pa
rtia
l or
com
ple
te in
spe
ctio
n, d
epe
ndi
ng
on
cu
lve
rt b
end
s, g
radi
ent
s,
len
gth
, e
tc.
4.1
.1.3
Laser
cro
ss-
secti
on
m
easu
rem
en
t
Cro
ss
-se
cti
on
m
ea
su
rem
en
t
• N
ot
ma
teri
al-d
epe
nde
nt
• D
N 1
50
to
DN
15
00
• U
se in
com
bin
atio
n w
ith t
ract
or
(se
e "
Tra
cto
r ca
me
ra")
• S
hu
t-d
ow
n a
nd
dra
ina
ge o
f the
con
du
it
ap
pro
x. 1
.80
–
2.2
5 €
/m
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s/c
ulv
ert
s:
• M
eth
od
no
t e
xplo
sio
n-s
afe
up
to n
ow
, su
itabi
lity
for
use
in p
ress
ure
wa
ste
-wa
ter
con
duits
and
cu
lve
rts
the
refo
re d
ubi
ous
(co
mpl
ete
exc
ha
ng
e o
f a
ir n
ece
ssa
ry)
• O
the
rwis
e s
uita
ble
for
me
asu
rem
ent
s of
def
orm
atio
ns
in P
E a
nd
PV
C p
ress
ure
co
ndu
its/c
ulv
ert
s a
nd
ma
y po
ssib
ly s
up
ply
info
rmat
ion
con
cern
ing
ma
teri
al e
rosi
on
caus
ed
, fo
r e
xam
ple
, b
y a
bra
sive
da
mag
e t
o in
tern
al c
oa
ting
s a
nd
/or
by
corr
osi
on
in
cast
-iro
n co
nd
uits
• se
e a
lso
"T
ract
or
cam
era
"
4.1
.1.4
1 A
ccord
ing to m
anufa
cture
r's in
form
atio
n 2 A
ccord
ing to m
anufa
cture
r's in
form
atio
n, s
upport
ed b
y exp
erience
fro
m p
ract
ical d
eplo
yments
in s
ome c
ases
3 T
ypic
al n
et co
sts,
deliv
ery
cos
ts to
be a
dded;
acco
rdin
g t
o su
pplie
r's in
form
atio
n, c
osts
vary
gre
atly
dependin
g o
n lo
cal b
oundary
conditi
ons
and o
rder
volu
me
in in
div
idual c
ases
4 E
stim
atio
n on t
he
basi
s of
pre
conditi
ons
for
use o
f th
e m
ethods
and
civ
il-engin
eering b
oundary
conditi
ons
of pre
ssure
conduits
, su
pport
ed b
y exp
erience
fro
m p
ract
ical
dep
loym
ents
in s
ome
case
s
41 IKT
InspectionT
able
2: In
tern
al-in
spect
ion m
ethods:
Insp
ect
ion
robots
– P
reco
nditi
ons
for
use
and
applic
abili
ty in
pre
ssure
wast
e-w
ate
r co
nduits
and c
ulv
ert
s
Meth
od
In
sp
ecti
on
aim
1
Co
nd
uit
mate
ria
l
an
d n
om
inal d
iam
ete
rs1
Mo
st
imp
ort
an
t p
reco
nd
itio
ns f
or
use
1
Co
st
rate
s,
exam
ple
s2
Su
itab
ilit
y fo
r u
se i
n
pre
ssu
re w
aste
-wate
r co
nd
uit
s a
nd
cu
lvert
s3
see f
ull
vers
ion,
Sect
ion
Ins
pe
cti
on
ro
bo
ts
Ca
me
ra
Op
tic
al
ins
pe
cti
on
• N
ot
ma
teri
al-d
epe
nde
nt
• D
N 7
5 –
DN
750
• In
spe
ctio
n p
ort
s in
cou
rse
of c
on
du
it,
spac
ing
50
0 m
as
fro
m D
N 1
30,
eve
ry 1
00
m
be
low
th
is
• S
hu
t-d
ow
n a
nd
dra
ina
ge o
f the
con
du
it
ap
pro
x.
3,0
00
-5,0
00 €
/d
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s/c
ulv
ert
s:
• M
eth
od
no
t e
xplo
sio
n-s
afe
up
to n
ow
, su
itabi
lity
for
use
in p
ress
ure
wa
ste
-w
ate
r co
nd
uits
an
d cu
lve
rts
the
refo
re d
ubi
ous
(co
mp
lete
exc
ha
ng
e o
f ai
r n
ece
ssa
ry)
• In
spe
ctio
n r
ob
ots
ap
pe
ar
to b
e su
itab
le f
or
cond
uits
fea
turin
g b
en
ds a
nd
gra
die
nt
len
gth
s
• In
form
atio
na
l va
lue
of
optic
al i
nsp
ectio
n r
estr
icte
d
4.1
.2
Ult
ras
on
ics
M
ea
sure
me
nt
of
wa
ll
thic
kn
ess
• S
tee
l
• D
N 1
30
– D
N 7
50
• In
spe
ctio
n p
ort
s in
cou
rse
of c
on
du
it,
spac
ing
20
0 to
1,0
00 m
, de
pen
din
g o
n c
ond
uit
dia
me
ter
• S
hu
t-d
ow
n a
nd
dra
ina
ge o
f the
con
du
it
• C
lea
n p
ipe
surf
ace
• C
om
ple
te fi
llin
g o
f th
e c
on
duit
with
pa
rtic
le-f
ree
w
ate
r
ap
pro
x.
7,0
00
-10
,00
0 €
/d
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s/c
ulv
ert
s:
• M
eth
od
no
t e
xplo
sio
n-s
afe
up
to n
ow
, su
itabi
lity
for
use
in p
ress
ure
wa
ste
-w
ate
r co
nd
uits
an
d cu
lve
rts
the
refo
re d
ubi
ous
(co
mp
lete
exc
ha
ng
e o
f ai
r n
ece
ssa
ry)
• F
or
use
onl
y in
ste
el c
on
duits
, th
ere
fore
on
ly in
fre
qu
ent
pote
ntia
ls f
or
use
• C
om
ple
te fi
llin
g w
ith c
lea
n,
part
icle
-fre
e w
ate
r in
cle
an p
ipe
diff
icul
t to
im
ple
me
nt
4.1
.2
Ed
dy
cu
rre
nt,
co
mb
ine
d w
ith
pe
rma
ne
nt
ma
gn
et
De
tec
tio
n o
f
ch
an
ges
in
wa
ll th
ick
nes
s a
nd
/or
co
rro
sio
n
• S
tee
l D
N 4
00
– D
N 7
50
• P
roto
typ
e fo
r ca
st-ir
on
co
ndu
its
DN
40
0 –
DN
60
0
• In
spe
ctio
n p
ort
s in
cou
rse
of c
on
du
it
eve
ry 3
00
m
ap
pro
x. 7
,00
0-
10
,000
€/d
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s/c
ulv
ert
s:
• M
eth
od
no
t e
xplo
sio
n-s
afe
up
to n
ow
, su
itabi
lity
for
use
in p
ress
ure
wa
ste
-w
ate
r co
nd
uits
an
d cu
lve
rts
the
refo
re d
ubi
ous
(co
mp
lete
exc
ha
ng
e o
f ai
r n
ece
ssa
ry)
• P
oss
ibly
of i
nte
rest
fo
r th
e in
spe
ctio
n o
f cas
t-iro
n c
ond
uits
onc
e t
he in
spe
ctio
n
tech
no
log
y h
as
be
en c
om
ple
ted
4.1
.2
1 A
ccord
ing to m
anufa
cture
r's in
form
atio
n 2 T
ypic
al n
et co
sts,
deliv
ery
cos
ts to
be a
dded;
acco
rdin
g t
o su
pplie
r's in
form
atio
n, c
osts
vary
gre
atly
dependin
g o
n lo
cal b
oundary
conditi
ons
and o
rder
volu
me
in in
div
idual c
ases
3 E
stim
atio
n on t
he
basi
s of
pre
conditi
ons
for
use o
f th
e m
ethods
and
civ
il-engin
eering b
oundary
conditi
ons
of pre
ssure
conduits
, su
pport
ed b
y exp
erience
fro
m p
ract
ical
dep
loym
ents
in s
ome
case
s
42IKT
Table
3: In
tern
al-in
spect
ion m
ethods:
Insp
ect
ion
pig
s – P
reco
nditi
ons
for
use
and a
pplic
abili
ty in
pre
ssure
wast
e-w
ate
r co
nduits
and c
ulv
ert
s
Meth
od
In
sp
ecti
on
aim
1
Co
nd
uit
mate
ria
l1
Mo
st
imp
ort
an
t p
reco
nd
itio
ns f
or
use
1
Co
st
rate
s,
exam
ple
s2
Su
itab
ilit
y fo
r u
se i
n
pre
ssu
re w
aste
-wate
r an
d c
ulv
ert
s3
see f
ull
vers
ion,
Sect
ion
Ins
pe
cti
on
pig
s
Ult
raso
nic
s
• M
ea
su
rem
en
t o
f w
all
th
ick
nes
s/c
orr
os
ion
(q
ua
ntit
ativ
e)
• In
sp
ec
tio
n f
or
cra
ck
ing
• S
tee
l
• P
oss
ibly
ca
st s
tee
l
• P
oss
ibly
su
itab
le fo
r use
with
P
E a
nd
PV
C
• M
eth
od
s g
ene
rally
ava
ilab
le fro
m D
N 8
0 t
o 2
00
, d
ep
end
ing
on p
roce
du
re a
nd
ma
nufa
ctu
rer
• A
ccess
po
rt w
ith fix
ed
or
tem
po
rary
pig
gin
g v
alv
e
• D
iffe
rentia
l pre
ssu
re o
f 0
.5 to
2 b
ar
ab
ove
o
pe
ratin
g p
ress
ure
fo
r p
ig p
rop
uls
ion
, p
lus
0.5
to
2
ba
r fo
r st
art
ing
of th
e p
ig (
dep
en
din
g o
n p
ig a
nd
p
ipe
ma
teri
al)
• C
on
du
it n
ego
tiab
ility
: m
inim
um
co
nd
uit
be
nd
ra
dii
ge
ne
rally
1.5
to
3-f
old
pip
e d
iam
ete
r n
ece
ssa
ry;
no
obst
ruct
ion
s ca
use
d b
y fo
ulin
g o
r im
pin
gin
g
valv
e d
iscs
, e
tc.
• U
ltra
son
ics:
com
ple
te fill
ing
of th
e c
on
du
it w
ith
cle
an
, pa
rtic
le-f
ree
wa
ter
• A
coust
ic le
ak
loca
tion
: a
min
imu
m p
ress
ure
n
ece
ssa
ry (
ap
pro
x. 3
ba
r)
fro
m a
pp
rox.
6
0,0
00
-8
0,0
00
€/d
ep
loym
en
t
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se t
est
ed o
nly
in s
teel c
on
duits
up t
o n
ow
; ra
tiona
l in
ind
ivid
ua
l case
s o
nly
, d
ue
to
hig
h c
ost
s
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.1
Str
ay m
ag
neti
c
flu
x
• D
ete
ctio
n o
f
ch
an
ges
in
wa
ll t
hic
kn
ess
a
nd
co
rro
sio
n (
qu
alit
ativ
e)
• In
sp
ec
tio
n f
or
cra
ck
ing
• S
tee
l
• p
oss
ibly
ca
st-i
ron
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se t
est
ed o
nly
in s
teel c
on
duits
up t
o n
ow
,
ratio
na
l in
ind
ivid
ua
l case
s o
nly
, d
ue
to
hig
h c
ost
s
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.2
Ed
dy
cu
rren
t
• M
ea
su
rem
en
t o
f g
eo
me
try
• D
ete
ctio
n o
f
ch
an
ges
in
wa
ll t
hic
kn
ess
a
nd
/or
co
rro
sio
n
(qu
alit
ativ
e)*
• In
sp
ec
tio
n f
or
cra
ck
ing
*
• S
tee
l
• p
oss
ibly
ca
st-i
ron
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se t
est
ed o
nly
in s
teel c
on
duits
up t
o n
ow
,
ratio
na
l in
ind
ivid
ua
l case
s o
nly
, d
ue
to
hig
h c
ost
s
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.3
Mech
an
ical
measu
rem
en
t o
f g
eo
metr
y
• M
ea
su
rem
en
t o
f g
eo
me
try
• N
ot
ma
teri
al-
dep
en
de
nt
fro
m a
pp
rox.
1
5,0
00
€/d
ep
loym
en
t
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se c
on
ceiv
ab
le,
ne
cess
ary
to d
ete
rmin
e c
on
duit
ne
go
tiabili
ty (
in t
erm
s of
be
nds
and
obst
ruct
ion
s)
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.4
Aco
usti
c l
eak
locati
on
•
Le
ak
lo
ca
tio
n
• In
prin
cip
le
no
t m
ate
ria
l-de
pen
de
nt*
* a
pp
rox.
6,0
00
-1
1,0
00
€/d
ep
loym
en
t
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se c
on
ceiv
ab
le f
or
leak
loca
tion
follo
win
g tig
htn
ess
test
ing
, b
ut
rest
rict
ed
suita
bili
ty d
ue
to
ne
cess
ity o
f co
mp
lete
fill
ing a
nd a
min
imum
pre
ssu
re
• D
ete
cta
bili
ty o
f le
aks
po
ssib
ly r
est
rict
ed
by
the s
ea
ling
effe
cts
of
fou
ling
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.5
Geo
deti
c
locati
ng
•
Lo
ca
tin
g
• N
ot
ma
teri
al-
dep
en
de
nt
No
da
ta
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se c
on
ceiv
ab
le (
dep
end
ing o
n c
ost
s),
nece
ssa
ry t
o d
ete
rmin
e c
on
duit
ne
go
tiabili
ty (
in t
erm
s o
f be
nds
an
d o
bst
ruct
ions)
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.6
Cam
era
•
Op
tic
al
ins
pe
cti
on
•
No
t m
ate
rial-
dep
en
de
nt
No
da
ta
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• V
isib
ility
re
strict
ed
du
e t
o p
ropu
lsio
n u
sin
g w
ate
r, in
add
itio
n to
re
stri
cte
d
info
rma
tion
al v
alu
e o
f op
tica
l in
spect
ion
: u
se th
ere
fore
no
t re
com
me
nd
able
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3.7
Lo
cato
r tr
an
sm
itte
r (f
oa
me
d-p
last
ic p
ig
fro
m w
ast
e-w
ate
r se
cto
r)
• C
on
du
it l
oc
ati
on
•
No
t m
ate
rial-
dep
en
de
nt
Co
st e
xam
ple
: C
on
du
it
DN
80
, 4
20
m le
ng
th:
2,3
00
-3
,90
0 €
/dep
loym
en
t
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• G
oo
d b
en
d-c
ap
abili
ty t
ha
nks
to c
om
bin
atio
n o
f fo
am
ed
-pla
stic
pig
and
lo
cato
r tr
an
smitt
er,
use
th
ere
fore
poss
ible
in p
rinc
iple
• C
ost
ly,
du
e t
o n
ece
ssity
of
wa
lkin
g t
he
ro
ute
on
the
su
rfa
ce
Cu
lve
rts
:
• N
ot
suita
ble
in p
rin
cip
le f
or
civi
l-e
ngin
ee
rin
g b
oun
da
ry c
on
diti
on
s
4.1
.3
* P
ure
ly e
ddy-
curr
ent
insp
ect
ion a
pplic
able
only
in c
ase
of lo
w w
all
thic
knes
ses,
there
fore
com
bin
atio
n w
ith o
ther
insp
ect
ion tech
nolo
gie
s in
som
e ca
ses
*
* w
here
typ
ical b
ack
gro
und n
ois
e genera
ted b
y th
e c
onduit
mat
erial c
an b
e filt
ere
d o
ut
1 A
ccord
ing to m
anufa
cture
r's in
form
atio
n 2 T
ypic
al n
et co
sts,
deliv
ery
cos
ts to
be a
dded;
acco
rdin
g t
o su
pplie
r's in
form
atio
n, c
osts
vary
gre
atly
dependin
g o
n lo
cal b
oundary
conditi
ons
and o
rder
volu
me
in in
div
idual c
ases
3 E
stim
atio
n on t
he
basi
s of
pre
conditi
ons
for
use o
f th
e m
ethods
and
civ
il-engin
eering b
oundary
conditi
ons
of pre
ssure
conduits
, su
pport
ed b
y exp
erience
fro
m p
ract
ical
dep
loym
ents
in s
ome
case
s
43 IKT
Inspection T
able
4: I
nter
nal-i
nspe
ctio
n m
etho
ds: F
loat
ed-in
and
dra
wn
tech
nolo
gies
– P
reco
nditi
ons
for
use
and
appl
icab
ility
in p
ress
ure
was
te-w
ater
con
duits
and
cul
vert
s
Met
ho
d
Insp
ecti
on
aim
1
Co
nd
uit
mat
eria
l
and
no
min
al
dia
met
ers1
Mo
st im
po
rtan
t p
reco
nd
itio
ns
for
use
2
Co
st r
ate
s,
exam
ple
s3
Su
itab
ility
fo
r u
se i
n
pre
ssu
re w
aste
-wat
er c
on
du
its
and
cu
lver
ts4
see
full
vers
ion,
S
ectio
n
Flo
at-
in a
nd
dra
wn
me
tho
ds
Dra
wn
-in
m
ech
anic
al
dia
met
er a
nd
d
efo
rmat
ion
m
easu
rin
g
sys
tem
• D
ete
rmin
ati
on
of
dia
me
ter
No
t m
ate
rial
-dep
en
den
t
• M
ea
sure
me
nt
of
de
form
ati
on
(o
valit
y)
Fle
xib
le p
ipe
s
• D
N 1
50
- D
N 1
200
• F
loa
ting
/dra
win
g-i
n o
f a
flush
ing
hos
e/r
ope
win
ch
an
d/o
r in
sert
ion
of
a c
am
era
for
con
veya
nce
of t
he
me
asu
ring
inst
rum
ent;
co
rres
pon
din
g a
cces
s p
ort
s n
ece
ssa
ry
• N
o s
hap
es
(be
nds)
in th
e c
on
duit
ap
pro
x. 1
.80
-3.0
0 €
/m
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s/c
ulv
ert
s:
• M
ea
sure
me
nt c
once
iva
ble
, b
ut r
are
ly u
sea
ble
, du
e to
lack
of b
en
d-c
apa
bili
ty
• R
an
ge
res
tric
ted
due
to
cab
le le
ng
th (
ma
x. 4
00
m)
and
inse
rta
bili
ty/f
loat
-in
ca
pab
ility
of
the
co
nve
yin
g e
lem
en
t (f
lush
ing
ho
se, w
inch
, cam
era
)
4.1.
4.1
Flo
at-i
n
hyd
rop
ho
ne
(e.g
. Sm
artB
all®
)
• L
ea
k lo
ca
tio
n
• L
oc
ati
on
of
air
po
cke
ts
• In
prin
cip
le
no
t m
ate
rial-
dep
end
ent
*
• D
N 2
00
– D
N 1
60
0**
• C
om
ple
te fi
llin
g o
f th
e c
on
duit
for
lea
k lo
catio
n;
oth
erw
ise
, de
tect
ion
of
air
poc
kets
• M
inim
um
pre
ssu
re 3
-4 b
ar
• M
inim
um
flo
w v
elo
city
0.1
5-0
.5 m
/s
• C
on
du
it a
cces
sib
ility
eve
ry 1
,10
0-1
,30
0 m
fo
r p
ositi
on
ing
of
sen
sors
• N
ece
ssa
ry t
o a
ssu
re c
ond
uit
neg
otia
bili
ty
ap
pro
x. 4
€/m
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se c
on
ceiv
ab
le f
or
de
tect
ion
of
lea
ks f
ollo
win
g t
igh
tne
ss t
est/
de
tect
ion
of
air
p
ock
ets
; d
ete
cta
bili
ty o
f le
aks
po
ssib
ly r
est
ricte
d d
ue t
o se
alin
g a
ctio
n o
f fo
ulin
g
• R
est
ricte
d u
sab
ility
, si
nce
min
imu
m p
ress
ure
, min
imum
flo
w v
elo
city
an
d
com
ple
te f
illin
g n
ece
ssa
ry
Cu
lve
rts
:
• N
ot
suita
ble
in p
rinci
ple
fo
r ci
vil-
en
gin
ee
ring
bo
und
ary
co
ndi
tion
s
4.1.
4.2
Dra
wn
-in
h
ydro
ph
on
e (e
.g. S
ahar
a®)
• L
ea
k lo
ca
tio
n
• L
oc
ati
on
of
air
po
cke
ts
• In
prin
cip
le
no
t m
ate
rial-
dep
end
ent
*
• D
N 1
00
– D
N 2
70
0
• C
om
ple
te fi
llin
g o
f th
e c
on
duit
for
lea
k lo
catio
n;
oth
erw
ise
, de
tect
ion
of
air
poc
kets
• M
inim
um
pre
ssu
re >
1 b
ar
• A
cces
s p
ort
s e
very
ap
pro
x. 1
00
– 1
,00
0 m
, d
ep
end
ing
on
flow
ve
loci
ty a
nd b
end
s
No
da
ta
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
sab
ility
se
vere
ly r
est
rict
ed
: in
the
su
ppl
ier's
exp
eri
enc
e,
fou
ling
in t
he
pre
ssu
re w
ast
e-w
ate
r co
ndu
it te
nd
s to
se
al le
aks
• F
urt
he
r re
stric
ted
usa
bilit
y, d
ue t
o n
ece
ssa
ry m
inim
um
pre
ssu
re a
nd c
om
ple
te
fillin
g
• O
nly
pa
rtia
l ins
pec
tions
pos
sibl
e if
acc
ess
port
s la
ckin
g a
long
th
e c
ou
rse
of
the
con
duit
Cu
lve
rts
:
• N
ot
suita
ble
in p
rinci
ple
fo
r ci
vil-
en
gin
ee
ring
bo
und
ary
co
ndi
tion
s
4.1.
4.3
Dra
wn
-in
car
rier
-u
nit
wit
h r
ing
la
ser
gyr
osc
op
es
and
po
siti
on
en
cod
ers
(e
.g.
Duc
tRun
nerT
M)
• L
oc
ati
ng
• In
prin
cip
le
no
t m
ate
rial-
dep
end
ent
• D
N 4
0 –
DN
120
0
• F
loa
ting
-in o
f a s
teel
ca
ble
fo
r su
bse
que
nt d
raw
ing
-in
of t
he
me
asu
ring
inst
rum
en
t
• C
on
du
it n
ego
tiab
ility
: m
inim
um b
en
d r
ad
ii in
con
dui
t m
ust
be
1.5
to 3
-fo
ld p
ipe
dia
me
ter;
als
o, n
o
ob
stru
ctio
ns c
au
sed
by
fou
ling
de
pos
its a
nd
/or
imp
ing
ing
va
lve
dis
ks, e
tc.
ap
pro
x. 4
,00
0 €
/d
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s/c
ulv
ert
s:
• M
ea
sure
me
nt c
once
iva
ble
, g
ive
n c
orr
esp
on
din
g b
end
-cap
abi
lity
for
the
in
stru
men
t
• In
spe
ctab
ility
prim
aril
y d
epe
nde
nt
on
abi
lity
to f
lush
in s
teel
ca
ble
• C
on
du
it's
cap
abi
lity
to w
ithst
and
load
s e
xert
ed
by
ste
el c
ab
le in
ben
ds
mus
t be
in
vest
iga
ted
, pa
rtic
ula
rly
in th
e ca
se o
f asb
est
os-
cem
en
t con
du
its
4.1.
4.4
* pr
ovid
ed t
ypic
al b
ackg
roun
d no
ise
gene
rate
d by
the
con
duit
mat
eria
l can
be
filte
red
out
** s
uita
ble
for
use
betw
een
DN
200
and
DN
600
, w
ith r
estr
ictio
ns
1 Acc
ordi
ng to
man
ufac
ture
r's in
form
atio
n 2 A
ccor
ding
to m
anuf
actu
rer's
info
rmat
ion,
sup
port
ed b
y ex
perie
nce
from
pra
ctic
al d
eplo
ymen
ts in
som
e ca
ses
3 T
ypic
al n
et c
osts
, del
iver
y co
sts
to b
e ad
ded;
acc
ordi
ng t
o su
pplie
r's in
form
atio
n, c
osts
var
y gr
eatly
dep
endi
ng o
n lo
cal b
ound
ary
cond
ition
s an
d or
der
volu
me
in in
divi
dual
cas
es
4 Est
imat
ion
on t
he b
asis
of
prec
ondi
tions
for
use
of t
he m
etho
ds a
nd c
ivil-
engi
neer
ing
boun
dary
con
ditio
ns o
f pre
ssur
e co
ndui
ts, s
uppo
rted
by
expe
rienc
e fr
om p
ract
ical
dep
loym
ents
in s
ome
case
s
44IKT
Tabl
e 5:
Ext
erna
l-ins
pect
ion
met
hods
: Met
hods
for
insp
ectio
n of
exp
osed
pip
es -
Pre
cond
ition
s fo
r use
and
app
licab
ility
in p
ress
ure
was
te-w
ater
con
duits
and
cul
verts
Met
ho
d In
spec
tio
n a
im1
Co
nd
uit
mat
eria
l an
d n
om
inal
d
iam
eter
s1
Mo
st im
po
rtan
t p
reco
nd
itio
ns
for
use
2 C
ost
rat
es,
exam
ple
s3 S
uit
abili
ty f
or
use
in
pre
ssu
re w
aste
-wat
er c
on
du
its
and
cu
lver
ts4
see
full
vers
ion,
S
ectio
n
Insp
ectio
n of
exp
osed
pip
es
Ele
ctro
mag
net
ic
insp
ecti
on
sy
stem
s (e
.g. S
LOF
EC
TM)
• D
etec
tion
of
chan
ges
in w
all
thic
knes
s an
d/o
r co
rro
sio
n (q
ualit
ativ
e)
• S
teel
, cas
t iro
n
• fr
om a
ppro
x. D
N 5
0
• U
ncov
erin
g of
the
pipe
sec
tor t
o be
insp
ecte
d
• P
ossi
bly
nece
ssar
y to
rem
ove
anti-
corr
osio
n co
atin
gs, d
epen
ding
on
mat
eria
l and
thic
knes
s
• K
now
ledg
e of
the
cond
uit m
ater
ial a
nd o
rigin
al w
all
thic
knes
s ne
cess
ary
for c
alib
ratio
n of
the
mea
surin
g in
stru
men
t
appr
ox. 2
,000
€/d
Pre
ssu
re w
aste
-wat
er c
ond
uits
:
• M
etho
d su
itabl
e in
prin
cipl
e fo
r use
with
cas
t-iro
n an
d st
eel p
ress
ure
was
te-
wat
er c
ondu
its
• Li
mite
d in
form
atio
nal v
alue
of r
ando
m-s
ampl
ing
insp
ectio
n
Cu
lver
ts:
• U
ncov
erin
g of
cul
vert
norm
ally
not
pos
sibl
e, d
ue to
the
obst
acle
s tr
aver
sed
4.2.
1.1
Ult
raso
nic
m
easu
rin
g
syst
ems
(e.g
. DS
M G
O)
• M
easu
rem
ent o
f wal
l th
ickn
ess
(dis
tribu
ted
mea
sure
men
t of p
ipe
wal
l)
• fo
r st
eel,
cast
iron
, PE
, in
ter a
lia
• N
ot d
epen
dent
on
DN
• U
ncov
erin
g of
the
pipe
to b
e in
spec
ted
• P
ossi
bly
nece
ssar
y to
rem
ove
anti-
corr
osio
n co
atin
gs, d
epen
ding
on
mat
eria
l and
thic
knes
s
• K
now
ledg
e of
the
cond
uit m
ater
ial a
nd o
rigin
al w
all
thic
knes
s ne
cess
ary
for c
alib
ratio
n of
the
mea
surin
g in
stru
men
t
appr
ox. 5
0-90
€/h
(M
easu
ring
inst
rum
ent:
ap
prox
. 8,0
00 €
)
Pre
ssu
re w
aste
-wat
er c
ond
uits
:
• M
etho
d su
itabl
e in
prin
cipl
e fo
r use
with
cas
t-iro
n an
d st
eel p
ress
ure
was
te-
wat
er c
ondu
its
• E
xtre
mel
y re
stric
ted
info
rmat
iona
l val
ue d
ue to
onl
y di
strib
uted
insp
ectio
n us
ing
ultr
ason
ic p
robe
Cu
lver
ts:
• U
ncov
erin
g of
cul
vert
norm
ally
not
pos
sibl
e, d
ue to
the
obst
acle
s tr
aver
sed
4.2.
1.2
Ult
raso
nic
m
easu
rin
g
syst
ems
(e.g
. Wav
emak
erT
M)
• D
etec
tion
of e
xten
sive
co
rro
sio
n a
nd
crac
kin
g (in
spec
tion
of
cond
uit s
ectio
ns)
• S
teel
, cas
t iro
n
• D
N 2
5 –
DN
100
0
• U
ncov
erin
g of
the
cond
uit a
t int
erva
ls o
f 1 to
50
m,
depe
ndin
g on
con
duit
mat
eria
l, in
clud
ed s
ocke
ts,
flang
es, w
elds
, ben
ds, e
tc.
• K
now
ledg
e of
the
cond
uit m
ater
ial a
nd o
rigin
al w
all
thic
knes
s ne
cess
ary
for c
alib
ratio
n of
the
mea
surin
g in
stru
men
t
appr
ox. 2
,000
€/d
Pre
ssu
re w
aste
-wat
er c
ond
uits
:
• M
etho
d no
t pra
ctic
able
, due
to n
eces
sity
of u
ncov
erin
g pi
pe s
ectio
ns a
t sho
rt
inte
rval
s, r
ange
of u
ltras
onic
sig
nal i
n th
e ca
se o
f bitu
men
-coa
ted
cond
uits
is
estim
ated
at 1
to 5
m, f
or e
xam
ple
Cu
lver
ts:
• U
ncov
erin
g of
cul
vert
norm
ally
not
pos
sibl
e, d
ue to
the
obst
acle
s tr
aver
sed
4.2.
1.2
1 Acc
ordi
ng to
man
ufac
ture
r's in
form
atio
n 2 A
ccor
ding
to m
anuf
actu
rer's
info
rmat
ion,
sup
port
ed b
y ex
perie
nce
from
pra
ctic
al d
eplo
ymen
ts in
som
e ca
ses
3 Typ
ical
net
cos
ts, d
eliv
ery
cost
s to
be
adde
d; a
ccor
ding
to s
uppl
ier's
info
rmat
ion,
cos
ts v
ary
grea
tly d
epen
ding
on
loca
l bou
ndar
y co
nditi
ons
and
orde
r vo
lum
e in
indi
vidu
al c
ases
4 E
stim
atio
n on
the
basi
s of
pre
cond
ition
s fo
r us
e of
the
met
hods
and
civ
il-en
gine
erin
g bo
unda
ry c
ondi
tions
of p
ress
ure
cond
uits
, sup
porte
d by
exp
erie
nce
from
pra
ctic
al d
eplo
ymen
ts in
som
e ca
ses
45 IKT
InspectionT
able
6:
Ext
ern
al-in
spect
ion m
eth
ods:
Meth
ods
for
insp
ect
ion o
f so
il-co
vere
d p
ipes
– P
reco
nditi
ons
for
use
and a
pplic
abili
ty in
pre
ssure
wast
e-w
ate
r co
nduits
and c
ulv
ert
s
Meth
od
In
sp
ecti
on
aim
1
Co
nd
uit
mate
ria
l
an
d n
om
inal
dia
mete
rs1
Mo
st
imp
ort
an
t p
reco
nd
itio
ns f
or
use
2
Co
st
rate
s,
exam
ple
s3
Su
itab
ilit
y f
or
use i
n
pre
ssu
re w
aste
-wate
r co
nd
uit
s a
nd
cu
lvert
s4
see f
ull
vers
ion,
Sect
ion
Ins
pe
cti
on
of
bu
rie
d p
ipe
s
Aco
usti
c
leak l
ocati
on
(g
round m
icro
phone)
• L
ea
k l
oc
ati
on
• In
prin
cip
le
no
t m
ate
ria
l-de
pen
de
nt
• In
prin
cip
le
no
t d
ep
end
en
t o
n D
N
• M
inim
um
pre
ssu
re o
f 1
to
10
ba
r, d
epe
ndin
g o
n
pip
e m
ate
rial
• C
om
ple
te fill
ing
of
the
co
ndu
it
ap
pro
x. 2
70
€/2
h,
for
eve
ry f
urt
he
r ho
ur
ap
pro
x. 7
5 €
/h
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• S
uita
bili
ty d
ub
iou
s, d
ue
to
a n
um
be
r o
f fa
cto
rs, su
ch a
s in
terf
ere
nce
fro
m
pu
mp n
ois
e, a
nd a
lso
th
e n
ece
ssa
ry m
inim
um
pre
ssu
re a
nd
co
mp
lete
fill
ing
• In
th
e s
up
plie
r's e
stim
atio
n, fo
ulin
g in
pre
ssu
re w
ast
e-w
ate
r co
ndu
its t
en
ds
to
sea
l le
aks
Cu
lve
rts
:
• N
ot
poss
ible
, d
ue t
o p
ass
age
un
de
r o
bst
ruct
ions
in t
he
co
ndu
it ro
ute
4.2
.2.1
Leak lo
cati
on
usi
ng d
isso
lve
d
heliu
m
• L
ea
k lo
ca
tio
n
• In
prin
cip
le
no
t m
ate
ria
l-de
pen
de
nt
• In
prin
cip
le
no
t d
ep
end
en
t o
n D
N
• F
aci
lity
for
conn
ect
ion
of a
me
teri
ng
sys
tem
(e
.g.
flan
ge
in t
he
pum
pin
g s
tatio
n)
• M
inim
um
pre
ssu
re o
f 1
ba
r, w
ith c
orr
esp
on
din
g
com
ple
te f
illin
g o
f th
e p
ipe
se
ctio
n to
be in
spect
ed
ap
pro
x. 5
,30
0 –
6
,30
0 €
fo
r le
ak
loca
tion o
n a
1 k
m
con
du
it
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• L
ea
k lo
catio
n u
sin
g d
isso
lve
d h
eliu
m a
pp
ea
rs to
be p
oss
ible
an
d p
ract
icab
le;
the
pre
con
diti
on
is fill
ing o
f th
e c
ond
uit
sect
ion
s w
ith h
eliu
m-e
nri
che
d w
ate
r (p
on
din
g a
t th
e e
nd
of th
e p
ress
ure
co
nd
uit
ma
y be
nece
ssa
ry)
Cu
lve
rts
:
• R
est
rict
ed s
uita
bili
ty,
de
pe
nd
ing
on
th
e o
bst
acl
e t
rave
rse
d (
e.g
. ri
ver)
, m
ust
be
a
ntic
ipate
d
4.2
.2.2
Th
erm
og
rap
hy
• L
ea
k lo
ca
tio
n
• C
on
du
it l
oc
ati
on
• In
prin
cip
le
no
t m
ate
ria
l-de
pen
de
nt
• In
prin
cip
le
no
t d
ep
end
en
t o
n D
N
• T
em
pe
ratu
re d
iffe
ren
ces
ge
nera
ted
by
pre
ssu
re
con
du
it/le
aks
ne
cess
ary
• O
nly
su
itab
le f
or
cond
uits
no
t lo
cate
d in
built
-up
a
rea
s
• N
ece
ssity
for
most
pre
cise
poss
ible
kn
ow
led
ge
of
the
co
ndu
it ro
ute
, a
nd a
lso
of
fact
ors
su
ch a
s so
il ty
pe
an
d v
ege
tatio
n
Walk
ing
of
the
ro
ute
w
ith a
ha
nd
-he
ld
cam
era
: 1
,500
€/d
O
verf
ligh
t
(ae
rial s
urv
ey)
:
> 9
,000
€/d
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• L
ea
k lo
catio
n m
ay
be
po
ssib
le,
bu
t pre
sup
pose
s va
ria
tions
in s
oil
mo
istu
re
con
ten
t ca
use
d b
y le
ak;
co
nditi
on
s m
ad
e m
ore
diff
icult
in m
an
y ca
ses
by
lack
o
f kn
ow
led
ge
of
the p
reci
se c
on
du
it ro
ute
• C
on
du
it lo
catin
g a
pp
ea
rs n
ot
to b
e p
oss
ible
, d
ue
to
on
ly s
ligh
t te
mp
era
ture
d
iffe
ren
ces
be
twe
en
the
wa
ste-w
ate
r a
nd
the
soil,
an
d a
lso
in m
an
y ca
ses
to
lack
of kn
ow
led
ge
of th
e p
reci
se c
on
du
it ro
ute
s
Cu
lve
rts
:
• N
orm
ally
no
t po
ssib
le, d
ue
to
pa
ssa
ge u
nde
r o
bst
ruct
ions
in th
e c
on
du
it ro
ute
4.2
.2.3
Gro
un
d-
pen
etr
ati
ng
rad
ar
• C
on
du
it l
oc
ati
on
• D
ete
ctio
n o
f
be
dd
ing
an
om
ali
es
• In
prin
cip
le
no
t m
ate
ria
l-de
pen
de
nt
• In
prin
cip
le
no
t d
ep
end
en
t o
n D
N
• P
ed
est
ria
n/v
eh
icle
acc
ess
ibili
ty o
f th
e a
rea
to
be
inve
stig
ate
d
• S
uita
bili
ty d
ep
en
de
nt
on
num
ero
us
bo
und
ary
co
nditi
on
s (s
uch
as
soil
typ
e, w
ate
r co
nte
nt,
g
rou
nd
wa
ter
tab
le,
salt
conte
nt,
te
rrain
su
rface
),
an
d m
ust
be
est
imate
d b
y su
pp
liers
in e
ach
in
div
idu
al c
ase
In
div
idua
l ra
da
r a
nte
nn
a:
2,5
00
– 3
,00
0 €
/d;
Co
mp
lex
me
asu
rin
g
tech
no
log
y*:
12
€/m
²
Pre
ss
ure
wa
ste
-wa
ter
co
nd
uit
s:
• U
se c
on
ceiv
ab
le,
bu
t as
ma
ny
bo
un
da
ry c
ond
itio
ns
of th
e s
ub-s
urf
ace
zo
ne
(a
nd
all
cond
uit
rou
tes,
in p
art
icu
lar)
sho
uld
be
kno
wn
, in
ord
er
to e
xclu
de
p
oss
ibili
ty o
f in
corr
ect
inte
rpre
tatio
ns
• C
on
du
it lo
catin
g c
om
ple
x (m
ove
me
nt
at
righ
t-a
ng
les
to t
he p
ipe
axi
s)
Cu
lve
rts
:
• S
uita
bili
ty d
ep
en
de
nt
on
pe
dest
rian
/ve
hic
le a
cce
ss to
th
e o
bst
acl
e t
rave
rsed
(s
ee
"P
ress
ure
wa
ste
-wa
ter
con
du
its"
for
furt
he
r n
ote
s)
4.2
.2.4
* E
xam
ple
: "D
etect
ino"
gro
und-p
enetr
atin
g r
adar,
featu
ring fiv
e r
adar
ante
nnas,
refe
renci
ng
func
tion
and e
lect
rom
agnetic
senso
rs
1 A
ccord
ing to m
anufa
cture
r's in
form
atio
n 2 A
ccord
ing to m
anufa
cture
r's in
form
atio
n, s
upport
ed b
y exp
erience
fro
m p
ract
ical d
eplo
yments
in s
ome c
ases
3 T
ypic
al n
et co
sts,
deliv
ery
cos
ts to
be a
dded;
acco
rdin
g t
o su
pplie
r's in
form
atio
n, c
osts
vary
gre
atly
dependin
g o
n lo
cal b
oundary
conditi
ons
and o
rder
volu
me
in in
div
idual c
ases
4 E
stim
atio
n on t
he
basi
s of
pre
conditi
ons
for
use o
f th
e m
ethods
and
civ
il-engin
eering b
oundary
conditi
ons
of pre
ssure
conduits
, su
pport
ed b
y exp
erience
fro
m p
ract
ical
dep
loym
ents
in s
ome
case
s
46IKT
and cost. In addition, the experience of the system operators participating indicates that pressure lines can be operated without problems occur-ring and without further examination throughout the design service-life, and beyond this in some cases, if odour problems caused by hydrogen sulphide are set aside. The efficiency of pressure waste-water conduits vis-à-vis gravity lines is also revealed in their daily operation. Functional prob-lems are discovered significantly earlier than in the case of gravity lines, particularly if delivery rates are MID-monitored and assessed against delivery pressures at the pumping station, machine speeds and energy consumption.
Operationally and cost-optimised provisions for determination of condition, rather than general-ised periodic inspections, therefore appear ration-al in the case of pressure waste-water conduits. The IKT has, jointly with the participating system operators, drafted a three-stage procedure:
Determination of conduit condition: recommendations for actionThe appropriate and rational scope of investiga-tion, and the investigation targets for pressure conduits, taking account of cost:benefit aspects, have been discussed on a co-operative basis with the steering committee of participating system operators on the basis of the information concern-ing the preconditions for use and costs of currently available methods, and the experience gained in test deployments. Generalised and regular inspec-tion of all pressure conduits, as is customary in the case of gravity lines, is consequently deemed to be unreasonably complex and expensive. The market can thus be said not to provide the technologies necessary to permit inspection of all conduits at rational expense. There are, for conduits of less than 100 mm diameter, scarcely any potentials for determination of condition, while inspection of larger-diameter conduits is possible only to a lim-ited degree, and/or at extremely high complexity
Stage 1: Data acquisition concerning the pressure-conduit systemAs a first stage, all available data on the pressure conduits operated should be compiled and con-tinuously updated. An obvious procedure here is to collate and record information on, for example, year of manufacture/installation and planned ser-vice-life, material and nominal diameter, informa-tion concerning any operational problems, damage and/or repairs which have occurred, and also data concerning catchment area and waste-water yield.
Stage 2: Risk assessmentThe best option for the second step is a risk assessment for every conduit, to permit a decision concerning whether, and to what extent, inspec-tions are necessary. Risk classifications of “Low”, “Medium” and “High” can be derived via estima-tion of the probability of occurrence of damage/operational failure and of the consequences/sever-ity of damage. The risk levels which are tolerable,
47 IKT
Inspection
and those at which provisions for minimisation must be initiated, must then be ascertained on the basis of the operator‘s safety requirements.
Stage 3: Provisions for determination of conditionPriorities, and the scope of any further provisions to be applied to the pressure conduit system, can be defined during the next stage, on the basis of the operator‘s risk assessment. There is always, in principle, a greater need for action in the case of high-risk conduits than in the case of medium-risk conduits.
The detailed recommendations for action can be found in the report – available for download at: www.ikt.de (German version)
OutlookDiscussion of the project results with the par-ticipating system operators confirmed the great need for more extensive investigations into the topic of “Determination of the condition of pres-sure waste-water conduits”. Five main focuses were established:
1. The recommendations for action elaborated during this project provide for the initiation of inspection provisions of a type and scope based on a risk assessment orientated around the probability and effects of damage to/fail-ure of/operational problems in pressure waste-water conduits. Up to now, however, there has been a lack of reliable evaluation criteria to permit substantiated determination of failure risks for estimation of the probability of dam-age/operational failure of such conduits.
2. The technologies currently available, including those intended for other types of conduit (gas systems, pipelines, etc.), do not permit eco-nomically rational use in pressure waste-water conduits. There is therefore an immense need for development of systems for the determina-tion of the condition of pressure waste-water conduits. It may be possible to combine methods already in widespread use in the waste-water sector, such as tractor cameras and foamed-plastic pigs, with more extensive inspection techniques used in the industrial sector. The use of new technologies is of inter-est in this context not only for determination of condition during conduit operation, but also
for the planning and tendering procedures for renewal and repair projects. Here, suitable requirement profiles for the (further) develop-ment of inspection methods have been drafted in close co-operation between system opera-tors and technology suppliers.
3. Tightness tests can be performed on pressure waste-water conduits only with significantly greater difficulty than on gravity lines as a result, for example, of the lack of facilities for access and/or venting. There are no dedicated technical codes and rules for the inspection of existing soil-covered pressure waste-water conduits. DIN EN 1610 [6] merely draws atten-tion, for the purpose of project acceptance, to the inspection procedures set down for drink-ing-water conduits in DIN EN 805 [7]. The extent to which this inspection method can be applied to existing pressure waste-water conduits at all, and the appropriate inspection criteria and limits, requires clarification.
4. The action chart developed does not, up to now, include any recommendations for the stipulation of intervals for determination of condition. Operational planning (estimation of expenditure) is significantly dependent on this, however. The extent to which general principles for the specification of intervals for determination of condition, or even guide figures for these intervals, can be developed, remains unclear at present.
5. Knowledge of the refurbishing/repair methods available on the market, and of their precondi-tions for use and their costs, is needed. The costs and the use of provisions for the deter-mination of the condition of pressure waste-water conduits should, on the one hand, be lower and simpler than those for repair and for renewal. Preparations for a repair/refurbishing project may, on the other hand, necessitate separate determination of condi-tion, such as, for example, measurements of deformations in the existing conduit.
Results available in the InternetThis article discusses only extracts from the research project. Both an abridged and a detailed complete version of the concluding report can be downloaded from the Internet at: www.ikt.de (German Version)
The AuthorDipl.-Ing. (FH) Kathrin SokollIKT - Institute for Underground Infrastructure
References[1] Harting, K.: Inspektion und Zustandserfas-
sung von Abwasserdruckleitungen und –dükern - Phase I, IKT - Institute for Under-ground Infrastructure, Gelsenkirchen, February 2011
[2] Bosseler, B.; Birkner, T.; Sokoll, O.; Brügge-mann, T.: Umsetzung der Selbstüberwa-chungsverordnung Kanal (SüwV Kan) bei kommunalen Netzbetreibern und Was-serverbänden in NRW. IKT - Institute for Underground Infrastructure, Gelsenkirchen, December 2003
[3] Bosseler, B.; Gronau, U.: Erfahrungsbericht – Reinigung und Inspektion von Dükern, Untersuchung im Auftrag des Ministerium für Umwelt und Naturschutz, Landwirtschaft und Verbraucherschutz des Landes NRW; IKT - Institute for Underground Infrastructure, Gelsenkirchen 2002
[4] DWA-A 116-2: Besondere Entwässerungsver-fahren, Teil 2: Druckentwässerungssysteme außerhalb von Gebäuden. DWA, Hennef, May 2007
[5] Leitlinien zur Durchführung dynamischer Kostenvergleichsrechnungen (KVR-Leitlin-ien), Länderarbeitsgemeinschaft Wasser (LAWA), 2005
[6] DIN EN 1610: Verlegung und Prüfung von Abwasserleitungen und -kanälen. Beuth Verlag, Berlin, October 1997
[7] DIN EN 805: Anforderungen an Wasserver-sorgungssysteme und deren Bauteile außer-halb von Gebäuden. Beuth Verlag, Berlin, March 2000
[8] DWA-M 143-6: Dichtheitsprüfungen beste-hender, erdüberschütteter Abwasserleitun-gen und -kanäle und Schächte mit Wasser, Luftüber- und Unterdruck - Inspektion, Instandsetzung, Sanierung und Erneuerung von Abwasserkanälen und -leitungen. DWA, Hennef, June 1998
[9] DWA-A 139: Einbau und Prüfung von Abwasserleitungen und -kanälen. DWA, Hennef, June 1998
48IKT
ABOUT IKT
Published: May 2012
Circulation: 3.000 copies
Protective charge: 19,95 e
The initial funding for setting up the institute has been provided by the Ministry for the Environment of the State of North-Rhine Westphalia, Germany‘s largest federal state.
However, IKT is not owned by the Government. Its owners are two associations which are
again non-profit organizations of their own:
a) IKT-Association of Network Operators: Members are more than 120 cities, among them Berlin, Hamburg, Cologne and London (Thames
Water). They hold together 66.6% of IKT.
b) IKT-Association of Industry and Service: Members are more than 60 companies.
They hold together 33.3% of IKT.
You can find information on projects and services at:
www.ikt.de
IKT - Institute for Underground Infrastructure is a research, consultancy and testing institute specialized in the field of sewers. It is neutral and independent and operates on a non-profit basis. It is oriented towards practical applications and works on issues surrounding underground pipe construction. Its key focus is centred on sewage systems. IKT provides scientifically backed analysis and advice.
IKT has been established in 1994 as a spin-off from Bochum University, Germany.
IKT – Institute for Underground Infrastructure
Exterbruch 145886 GelsenkirchenGermany
phone: +49 209 178060fax: +49 209 17806-88email: [email protected]
IKT is located ca. 30 min. off Düsseldorf International Airport.