Outlets to the drain should be PVC pipe with the rodent screens
, and should occur every 500' unless the slope is over 1%, in
which the length can be extended.
Another application where Multi-Flow can be most beneficial is in
the railroad yard where the lack of grade can create problems with
ponding water and attendant structural problems between the track
can be very straight forward, as most of these yards already have
some type of storm sewer or culvert conduits installed which service
surface inlets throughout the yard.
These can serve as outlets for the Multi-Flow collection system.
installation would be to create a 4 inch wide trench approximately
24 inches deep midway between the track sets (but probably not more
than 20 feet in any case). The 18-inch Multi-Flow would be centered
in the trench and then backfilled with the select granular material
mentioned previously, and consolidated. It may be advisable to allow
4 to 6 inches in the top of the trench to backfill with a class
#5 gravel to allow better compaction for surface traffic.
it is advisable to maintain 1% slope in the drain lines towards
the point of outlet. Further, best performance is achieved with
total run length of 400 feet or less between outlets.
the outlet is into a culvert or drain already located in the yard
as mentioned above, an inspection port adapter provided by Multi-Flow
will allow the water to exit the Multi-Flow system and drop down
using an ABS/PVC pipe to enter the deeper drain pipe system from
the top. This is very easy to achieve and takes advantage of the
high capacity outlet system already installed.
there be no exiting system to attach to, it may be necessary to
bring the drain to a central location point and install a deeper
transport pipe (PVC) to bring the collected water to a suitable
outlet or city storm drain.
Refurbishment of existing rail beds
Because of substantial variations in existing problems, structures
and materials that may be present in refurbishing situations two
different scenarios are noted for addressing the problem. It is
obvious that the more thorough method has a much greater chance
of a satisfactory outcome.
After removal of the rails and ties, all ballast and subballast
is bladed off. The subgrade is then inspected for integrity, and
any problem areas (such as bowls created by ballast encroachment)
excavated, filled with accepted material and compacted.
Multi-Flow is then installed by trenching in the center of the
roadbed using a minimum 8 inch deep trench with a minimum width
of 4 inches. After placing the drain in the center of the trench
it should be backfilled with a select granular material(between
a #10 and #30 US standard sieve) to the top. Consolidation can
be achieved by vibratory compaction or water jetting. Outlets
to daylight should be installed transversely at intervals 200'
to 400' depending on available slope.
can then be placed and compacted followed by the tie/ballasting
Local Repairs refers to the installation of Multi-Flow drainage
systems on existing track sections as a temporary measure to keep
the track usable until a permanent fix is completed, and must
be kept operational throughout the drainage installation.
will require that the drainage system be placed at the extreme
sides of the ballast section.
this method will drain significant amounts of water from the structure,
it will probably not be as successful as installing drainage in
a new or completely reconstructed rail bed. The reasons for this
are many and varied but include the fact that it is extremely
difficult to properly define and drain the "bowls" that
have developed due to poor subgrade conditions. Further it precludes
identifying and repairing any serious deficiencies in the subgrade.
The risk of contaminating the granular backfill is also a concern.
this situation, the placement of the 6-inch Multi-Flow will be
adjacent to, but not over 2 feet from the end of the ties, running
parallel to the rail.
depth of the trench will be deep enough so that it is at least
as deep as the "bowl" of the ballast section.
granular backfill material would be installed around the Multi-Flow
until it is deep enough to intersect the clean ballast section.
should be noted that using some device (chute or boot) would be
necessary to stabilize the ballast during trenching, placement
of the Multi-Flow, and backfilling in order to prevent it from
caving into the trench.
lateral outlets should be used to empty the drain system with
spacing not exceeding 200 to 400 feet would be preferential, depending
on available space.
"bowls" that are encountered that are deeper than the
Multi-Flow system should be addressed separately by installing
a 6-inch Multi-Flow drain laterally at or below the deepest level
of said bowl. These laterals should use the standard granular
mounted equipment does exist to do this type of installation,
however it would not be cost effective on relatively short jobs.
Track mounted machines which can straddle the rail and run on
the ties are available and would be suitable for smaller problem
the Multi-Flow system offers significant strength and performance
advantages, like any construction project, the outcome is entirely
dependant upon quality installation methods and procedure.
How Artificial Drainage Works