Note: Descriptions are shown in the official language in which they were submitted.
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DRAIN CHANNEL SYSTEM
The invenhon here pl~s~ d relates to a drain channel system desi~nPcl in particular for
the draining of partially and fi~lly sealed surfaces.
There have been earlier approaches to the draining of partially or fully sealed surfaces
5 with the aid of a seepage system. The method employed to date involves the inct~ tion of run-
offch~nn~l~ in the sealed sections which ch~nn~l~ lead into a system of drain pipes. The major
drawback of such a system lies in the fact that, over time, the drain pipes clog up, that servicing
these pipes is an e xtremely complex matter and that the soil around these pipes tends to settle.
The German patent DE 44 03 454 C1 describes a profiled, U-shaped concrete block or
drain tile that is open toward the top and serves as the intake section. This intake section is
provided with a biological screen the function of which is to biologically filter the incorning
water. The lower, holi~olltal section of the U-block features perforations allowing the water that
enters the charme:l to seep through these pel~ldlions into the soil lm-lerne~th the drain tile. The
1 5shortcorning of tbis channel consists in very lirnited draining efficiency and the potential for a
relatively rapid se:ttling of the soil lln(l~rne~th the concrete block. Moreover, it is quite difficult
with this design to compensate for differences in the amount of water collected o- er the length of
the channel, causi~g fairly quick flooding of the channel in overload situations.
2 0 DE 28 35 124 C2 describes a pipe system for soil irrigation and draining. This system
consists of tu-o pipes, one inside the other and both partially water-permeable at least in their
bottom sections. During the installation, the outer pipe with the larger diameter is slightly
flattened so as to ,ive it an ellipsoid profile with a somewhat broader irrigation or drainage
capacity. However, a pipe of this type is only suitable for watering and dewaterinv plants, given
2 'i that the influx of larger amounts of water, as in the case of drainage systems, could easily cause
the soil to pack down.
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DE-U-94 I S 774 describes a ground cover that can be assembled from profiled, square
stone tiles. Water can seep into the grooves between the stone tiles and drain off into the ground
through lateral duct channels molded into the tiles. Here again, the problem is relatively quick
clogging of the grooves at the points of entry of the drainage water due to the silting effect.
5 Besides, stone tiles of this type cannot be assembled into a contiguous surface in a way as to
permit easy movement for instance of shopping carts or forklifts.
The inven-tion here presented is aimed at avoiding these drawbacks, providing a drain
channel system which is easy to m~int~in while minimi~ing the potential for the soil to settle.
AccordinP to the invention, this is accomplished by means of the drain charmel system
per claims 1 and 12. Desirable design enhancements of the invention are covered in the
corresponding subclaims.
A common feature of all the drainage designs in the subclaims is an open dowllw~d
channel, i.e. inverted U section which receives the surface water. Located underneath this
continuous cavity is the seepage area with a ballast bed which may have a specific grain size
distribution so selected as to inhibit alluvial sedimentation while possibly promoting biological
growth. The air permeating the cavity of the channel section permits the accumulation of aerobic
2 0 bacteria, thus creating a certain subterranean biological cleaning process much like the one that
takes place in the natural topsoil (humus). In this fashion, the biorganic growth can bind ultrafine
particles and even toxic substances which counters the clogging of the seepage area and the
surrounding soil and may even be conducive to a partial organic purification of the drain water.
The seepage area may be separated from the cavity by a dirt filter such as a metal screen, a
;2 5 geofibrous fabric or a louvered separator capable of inhibiting the introduction of ultrafine
particles in the seepage area and again promoting biorganic growth. For pressure flushing or
vacuuming of the geofabric filter during maintenance work it is desirable to provide the fabric
with a reinforcing screen backing on one or both sides to prevent damage during the cleaning
process. In this conte~ct the cavity channel should be accessible from at least one end. The
channel section that is open toward the bottom receives the water either by way of an upper
charmel section or via a reservoir, a bo~ drain or some other surface water collection system (e.g.
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a gutter). The geofabric may be mounted in the channel in removable fashion. for in~t~nce in
lon~ in~l slots, so that it can be replaced in the event it is clogged by particulate matter. It is
possible to drain off water not orlly into the seepage area but also into the ~ul,~ol li~g bed next to
the ~ h~nn~l if it consists of a suitable m~tçri~l (for inct~nre gravel).
In a first e mbodiment of the drain channel according to this invention, the intake area is
ess~nti~lly the same as the seepage area In this system, a drain channel incl~ s an upper
channel section which receives the water from the sealed or partially sealed surface, and a
dowllw~d-pointing bottom section with a continuous cavity which receives the surface water for
1 () instance from the upper channel section by way of intermediate openings or, at its ends, from a
box drain or holding tank or other type of reservoir or tre~tment system. The water entering the
inverted U-shaped cavity of the channel bottom section seeps into the ground in the seepage area
ntl~rne~th the channel bottom section. The seepage area can be protected from clogging by
means of the aforementioned dirt filter such as a rodent-proof and backwash-protected fabric. In
15 one design concept, the mouth of the conduit leading into the upper charmel section is raised
above the gullet bottom of the upper channel section so as to protrude beyond the water level,
serving as an overflow device. As a result, dirt entering the upper channel section will
accl~mlll~te in the gullet and only clean water will flow through the conduit into the lower
channel section underneath. This virtually prevents any clogging of the conduits between the
2 0 upper and the lower channel sections. As an alternative, or in addition, a dirt filter may be
incorporated in the conduits between the upper and lower channels. Where a box drain is used,
the mouth of the lower channel section leading into the box drain is located above the bottom of
the box drain so that the latter serves as a settling tank. Coarse dirt particles and sand will settle
in the box drain or reservoir, so that the water entering the lower charmel is relatively clean. In
2 5 addition, or as an alternative, a dirt filter may be installed between the surface-water intake and
the cavity mouth leading into the box drain.
Compared to conventional systems employing drain pipes, this invention offers the
advantage of permitting the installation of the drainage and seepage system and the water run-off
in one operation. Such systems can even be retrofitted to existing, partially sealed surfaces. They
can be installed independent of any sewerage lines. It is not necessary for the run-off to be in the
forrn of continuous drainage lines. The channels may be installed in single units, a fact which
provides great flexibility in the layout of a partially sealed surface. Furthermore, the channels
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need not be sloped.
The fact tbat the space above the seepage area cont~in~ nothing but the drain channel
itself rather than additional soil as in the case of coll~elllional drain pipes, largely elimin~t~s the
5 settling of any such soil. This may be further enhanced by bracing the lower ch~nn~l sections
against wide concrete beds or by widening the seepage area and/or by flaring the downward
lateral supports i.e. side walls.
The drain channel is preferably desi~n~d in the form of two back-to-back coaxial U-
10 profiles whose open ends point in opposite directions, the right-side-up U-profile constituting the
upper channel secl:ion, the inverted U-profile under it constituting the lower chamlel section.
Where they meet, the upper and lower channel sections are slightly widened so as to form a
larger contact surface between them as well as a bilateral ledge in the transition area which aids
in the load distribution for the lower ch~nnel while serving as a backwash barrier for the upper
15 channel. The upper and lower charmel sections preferably consist of identical U-profiles which
reduces the tooling cost in the overall channel production.
The cross section of the gullet of the upper ch~nel section is preferably asymmetric, i.e.
the gullet is offset toward one of the vertical sidewalls, while the mouth of the conduit is
2 0 positioned off-center closer to the opposite channel wall, me~ning that the mouth of the conduit
is located in the inclining section of the gullet away from the base of the gullet. Dirt entering the
upper channel secfion thus accumulates on the bottom of the gullet while the mouth of the
conduit serves as the overflow. The circular holes for the conduits are drilled through the
identical, back-to-back U-profiles after assembly so as to avoid dirt and resulting water backup
2 5 due to otherwise possible aYial or lateral mi~lignment of the holes. The flared, preferably
circular transition in the openings ensures unirnpeded water flow between the upper and lower
channel sections even in the event of minor rnic~lignment. A dirt filter may be installed as well.
The profiled sections for the upper and lower channels -- whether identical or not -- are
preferably made o:f cast concrete, polymer concrete or a synthetic material.
Using a two-part drain channel has the advantage of considerably facilitated
transportation and on-site channel assembly. However, it is equally possible to use a single-mold
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channel the upper part of which opens up toward t_e top while its lower section opens up toward
the bottom. A drain channel of that type is ess~nti~lly H-~h~re~l Better draining efficiency is
obtained if the lcwer channel section is wider than the upper ~h~nn~l section, in that the cavity
and the seepage area lln~lPrn~th the ~ nn~l are larger than the intake area defined by the upper
5 ch~nn~l, thus ~nh~n~in~ the drainage capacity of the çh~nn~l
As described above, the water feed from the upper channel section to the lower ch~nnel
section can be obtained by means of vertical conduits extending through the partition
horizontally separating the upper from the lower channel section. However, as an ~It~rn~tive or
10 in addition thereto, a dry-well, box drain or reservoir may be installed at the end of a drain
channel for collecting the water entering the upper channel section and passing it on to the lower
channel section. In that case, the mouth of the lower channel section leading into the box drain
should be located sufficiently above the box-drain floor. The box drain, or reservoir as the case
may be, thus serves as a settling tank in which coarse dirt particles accumulate. An oil separator
15 may be installed in the area of the box drain and/or reservoir, permitting the drainage of slightly
oily surface water. In lieu of a reservoir or box drain a holding tank or water treatment system
may be connected for collecting the water entering through the upper channel section. The
function of the upper channel section can thus be temporally separated from that of the lower
channel section. It is also possible to use the upper and lower channel sections independently of
2 0 one another which significantly broadens their potential l~tili7~tion. The mouth of the lower
channel section leading into the box drain will then act as the overflow for the box drain throu h
which mouth only relatively clean water will flow. This will largely elimin~te dirt accurnulation
or clogging in the lower channel section. Preferably, a baffle is inserted in the mouth of the upper
channel section, e~ctçn~ling from the base of the gullet up to a specific height and preventin~ the
2 5 dirt accumulating in the gullet from entering the box drain. This provides for a double-screening
of coarse particles before they could enter the lower channel section.
The use of a box drain or reservoir has an added advantage in that it allows access to the
3 0 lower channel section, i.e. to the cavity in the latter, from one end for easy maintenance. Of
course, the box drain or reservoir can also be used for draining additional surfaces, for instance a
gutter or eaves. 1~he box drain or reservoir may also be equipped with an overflow leading into
the sewerage system. Providing an overflow at the appropriate level, i.e. above the lower channel
section, will prevent the water level in the lower channel from rising too high and affecting
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proper functioning of the overall drainage system.
This inven.tion is described with the aid of several examples and the st hPm~tic diagrarns
in which:
Fig. 1 shows the cross section of a two-part drain channel with a conduit b~l~eel~ the
upper and lower ~h~nnPI segments along line A-A in fig. 2;
Fig. 2 is a lateral view of a drain ç~l~nnel system including a box drain and two 2-part drain
channels connPcterl to it;
1()
Fig. 3 shows a longitu~lin~l section through a drain channel system including a drain channel
with a reservoir connected at one end, where the upper and lower channel se~Lents of the
drain charmel are separated from each other;
~5 Fig. 4 shows detail IV of the mouth of the upper channel segment of the drain channel per fig. 2
at the intalce into the box drain;
Fig. S shows a one-piece drain channel ~,vith integral upper and lower channel ses~nents;
2 () Fig. 6 shows a drain channel without the intake area; and
Fig. 7 is a cross section through a drain channel per fig. 6.
Illustrated in fig. i is a drain channel system 10 including a two-part drain channel 12 consisting
2 'i Of an upper channel section 14 and a lower channel section 16. The upper channel 14 and the
lower channel 16 are identical cast-concrete U-profile blocks. The two U-profiles 1~. 16 butt
against each other with their horizontal base 15, the said horizontal bases 15 constituting the
boundary between the intake area 18 and the downward cavity 20 of the drain channel 12. In the
longitudinal direction of the groove, the bottom contact surface 17 is provided with a rectangular
3 ~I serration serving to prevent the mortar used in the assembly from separating and floating into the
cavities while interlocking the upper and lower channel sections. Instead of a rectangular
serration, a deltoid or sinusoid serration will serve as well. Alternatively or additionally, the
serration may be provided perpendicular to the axis of the channel.
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The two top ends of the vertical legs of the upper charmel segment 14 each support an L-bracket
2~ (ledge) whose vertical legs point away from each other. This creates a frame for holding a
screening grate. 1. he upper edges of the L-brackets 22 are perfectly flush with a sealed surface
such as an asphalt layer 24 which is to be drained of water by the drain channel.
In the area of their horizontal contact base surfaces 15, the identical upper section 14 and louer
section 16 of the channel are provided with a collar 26, producing a larger contact surface
between the two ;ections 14, 16 for greater structural stability when these two segments 14, 16
are assembled. The upper channel 14 contains a gullet 28 which, in its cross section, is slightlv
1 Cl offset relative to its central axis, in this case toward the right side. Toward the left the gullet
follows an incline 29. Located in this incline 29 is the conduit opening 30 which connects the
intake area 18 ~i-th the cavity 20. The conduit opening 30 is flared toward the bottom or
horizontal base 15 ofthe upper channel section 14 into a circularly widened flange opening ~2
which matches the corresponding flange opening 32 of the identical lower channel section i6.
1 c, The conduits 30. 32 may optionallv be provided with a dirt filter 33 such as a metal screen, a
geofabric or a louvered separator preferablv mounted in exchangeable fashion. To assure thal the
flange opening ~ ~ of the upper char~nel section 14 will always line up with the flange opening 3~
of the lower charmel section 16 it is necessary to locate the openings in mirror-symmetric fashion
relative to the central axis of the channel. As sho~n in fig. 2, the openings 30, 32 are axially (i. e.
2 0 longitudinally) positioned in the center of each channel 1~. This will ensure that an~, identicaily
shaped block can be used for the upper as well as the lower channel section. The upper channei
section 1~ and the lower channel section 16 rest on a permeable layer of soil 3~ which,
underneath the drain channel, may be loosened up once more in the seepage area 36 and mi~e!l
with a rodent-proof and backwash-protected web installed in the plane between the cavitv '0 and
2 cl the seepage area 36. A web of this t~pe mav consist of a geofabric which protects the seepage
area 36 located underneath the cavitv 20 against the deposition of fine particles and thus against
premature clogging. The geofabric may also perforrn a control function for building a biomass in
the seepage area. The geofabric itself may be wider than the separating plane bet~een the ca~, irv
and the seepage area, allowing the channel to sit on the fabric. Since maintenance work should
3 Cl include the periodic cleaning of the geofabric. the latter mav be provided with a support screen or
netting on one or both sides. This ,~ill perrnit pressure-cleanin~ of the cavity and thus of the
geofabric withoul destroying the latter. Moreover, the interrnediate layer. i.e. the geofabric. ~ill
effectively protect the cavitv 20 against debris emanating from the seepage area 36. The drain
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channel 12 is held in place on the soil layer 34 by means of concrete fills 38 which fills widen
toward the bottorn in pyramidal fashion. The concrete fills 38 e~tend all the way to the upper end
of the widened collar 26 of the upper channel section 14, thus holding the upper charmel section
14 and the lower channel 16 in place relative to each other while at the same time providing
5 vertical support for the channel by butting agai~Lst the collar 26 in the plane of contact i.e. along
the base surfaces 15 of the two U-shaped segments 14, 16. This structure prevents the soil in the
area of the drain rhannel from settling. rhe channel thus supported is surrounded with a layer of
gravel or sand 39.
As illustrated in fig. 2, the two-part drain channel 12 may be connected at one end with a box
drain 40. The other end is closed off with a cap 42, preventing anv dirt around this cap 42 from
entering the drain channel 12. Both the upper channel section 1~ and the lower channel section
16 with their intake area 18 and, respectively, cavity 20 are open toward the box drain, as sho~n
for the upper cha]mel section 14 in fig. 4, with a detail IV from fig. ~. The openings 30, 32
between the upper channel section 14 and lower channel section 16 are represented bv a broken
line. Fig. 4 is a cross-sectional view of a detail at the end of the drain channel 12 where it
transitions into the box drain 40. The water which enters the intake area 18 (fig. 1) of the drain
channel 12 travels through an opening 44 of the upper char~el se~nent 14 and into the box drain
40. Toward the bottom, i.e. toward the base of the gullet 28, the oper~ing 44 is limited by a baffle
46 which e~tends from the base of the gullet 28 (fig. 1) up to a specific level within the intake
2 o area 18. This baf~le 46 serves to prevent the debris collected in the ~ullet 28 from entering into
the box drain 40. By way of another opening 48 further down, the lo~er channel section 16
connects to the box drain 40. Preferably, a dirt filter 47 is installed between the opening 44 of the
upper channel section and the opening 48 of the lower channel section to keep dirt away from the
cavity in the lower channel section and thus to prevent the seepage area in the ground from
2 5 clo ging. The bottom side of the opening 48 is at a certain distance from the floor of the bo~
drain 40, allov~in~J the latter to serve as a settling tank collectin~ coarse dirt particles. It follows
that the cavity 20 in the lower channel section 16 receives onl~ relatively clean water from the
bo~c drain 40 and therefore does not prematurely fill up with coarse dirt and sand.
3 0 The bo~ drain 40 may further serve to feecl waste water from other zones to be drained into the
ca~vit~ ~0 of the drain channel 1~ (for instance from eaves). The box drain 40 may also be
equipped with a s-wera~e connection ~ for use in cases where the drainaoe capacit~ of the drain
channel is too limited to handle all of the incoming water.
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Fig. 3 shows ano1her design version of a drain channel system with a two-part drain channel the
end of which leacls into a reservoir 5 l . Components physically or functionally identical to those
in the preceding figures bear the same reference nurnbers. The drain channel system 54
illustrated in fig. 3 is identical to that in fig. l, 2 and 4 except that no openings 30, 32 are
provided between the upper channel segment 14 and the lower channel segment l 6. The water
entering the upper channel section l 4 thus flows into the reservoir 5 l by way of an opening7 ~4 at
the channel end and preferably through a dirt filter 47. The bottom 50 of the reservoir S l is at a
considerable dist~mce d from the mouth 48 of the lower channel section l 6. Thus, any water
entering via the upper channel section l 4 is cleaned in the reservoir 51 much like in a settlinc
tank until it overflows via the end opening 48 into the cavity 20 of the lower ch~nnel section
from where it seeps into the ground as indicated by the arrows. At the far end from the reservoir
51, the cavity 20 is provided with a vent SS which allows the water to flow unimpeded from the
reservoir ~1 into -the cavity 20 of the lower channel section. A similar vent may be pro~,-ided in
the embodiment per fig. 2 as well. as long as there are no conduits or openings bet -een the u?per
and lower channel sections or where these openings do not permit adequate venting.
Fig. ~ shows anolher design version of a drain charmel whose upper and lower char~nel sections
are integrated into a single H-profile. Components physically or functionally identical to those in
the preceding figures bear the same reference numbers. rhe drain channel 58 essentially consists
of an H-profile 6() whose upper two legs 62 are closer together than the two vertical do~hn~arc
2 0 legs 64 below the horizontal base 66 which separates the inflow area 18 from the cavity ~0. B~
virtue of the fact that the lower two legs 64 are spaced farther apart. by a distance e. than the
upper vertical legs 62, the width of cavity 20 is substantially greater than that in the embodimlems
described earlier. In the drain channel 58 as well. the gullet 28 is asymmetric. i.e. offset to the
right. while the conduit 30 from the intake area l 8 to the cavity 20 e~tends throul7h the lert-har.d
2 5 incline 29 of the gullet 28. A dirt filter is preferably provided in this case to prevent the see?age
area from clogging. This particular design offers very good drainage perforrnance, it is
positionally very stable due to its wide stance and it can be installed with a minimum of
additional hold-down provisions. It lends itself especially well to situations where a lo~--profiie
drain channel is needed. for instance due to limited vertical space between the subsoil and Ihe
surface to be drained.
.~11 of the r~bo- e designs according to this invention have the advantage that. after removai or he
grate, the entire intake area l8 and thus the gullet is accessible from the top over its full ~~icth.
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permithn~ easy cleaning. If a box drain or reservoir is used, the cavity 20 as well is easily
accessible through the end opening 48 facing the box drain 40, permitting ap~lo~iate
m~intt n~nce on its part. During operation the opening 48 may be closed offwithL a plug. Even
without broad oultrigger mounts, all of the embo~limPnts minimi7~ any settling of the ground. A
5 widened lower channel section as per fig. S may also be incorporated in a two-part channel per
fig. 1 to 4. Of course, in that case the profiles of the upper and lower channel sections will not be
identical.
11~ ThLe openings 30, 32 between the upper and lower channel segments may be provided with a
screen as protection against coarse debris and ~nim~l~
All channel components may be fabricated from concrete, synthetics, metal or other popular
structural materials and compounds. The upper and lower channel sections may be produced
11~ from different materials.
For draining water from an overhead system such as eaves it may suffice to use a drain channel
with tbLe upper channel section, e.g. ch~nnel section 14 in fig. 1, left off. A drain channel of that
type thus consists merely of the lower channel section 16, albeit withL a closed rather than partly
2 1~ perrneable base 15. In that case, the channel is preferably connected at its end to the surface or
overhead drain gutter. A channel of this type may still be used in conjunction with intake drain
channels accordiI;Lg to the exarnples described above, in order to provide greater drainage
efficiency of the overall system.
2'~ Fig. 6 and 7 show a drain channel 70 with a subterranean channel body 72 having an open cavity
20 facing downward. At its end, the channel connects via a mouth 73 to a box drain 74. By wa
of a feed 76 the box drain 70 connects to a surface-water feed-in device. A dirt filter 47 is
preferably installed between the feed 76 and the mouth 73. Alternatively, the dirt filter, in this
case 49, may also be mounted directly at the mouth. The mouth 73 is located above the base 78
3 1) of the bo~ drain by a distance d. As can be seen in fig. 7, the space above the chanrLel body 72 is
a layer of asphalt 80.
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In general, the dr~in ~h~nnel~ of all the above design versions will be produced in the form of
axially connectable ch~nnel modules.
