Multi-Flow drainage systems are your best choice for draining paved surfaces. They are being used with excellent results along highways, city streets, runways, and under parking lots.

The rapid increase in Multi-Flow usage is part of a larger trend toward more artificial drainage under paved surfaces due to a more complete understanding of the relationship between good drainage and pavement life span. Cities and states are continually seeking to make pavements last longer in an effort to stretch budgets further.

A case for drainage under or along paved surfaces

Drainage dramatically extends the life of pavement. A recent FHWA survey reveals:

4 reasons why saturation contributes to premature pavement failure:

  1. Saturated bases and subbases quickly soften and lose load capacity.
  2. As vehicles move across the surface, a pumping action is triggered that washes fine particles from the soil creating voids.
  3. In cold climates, saturated soils expand when they freeze, causing frost heaves.
  4. Some soils expand when wet, distorting the surface shape.

Water can permeate the subbase or the base from three different sources

  1. High water table especially during periods of higher than average precipitation.
  2. Water moving laterally resulting from impermeable subsurface features
  3. Water entering from the surface. Paved surfaces are surprisingly permeable.

FHWA studies show that water permeates pavement at a surprising rate.

Typical infiltration rates:

  • Asphalt 33% to 50%
  • Concrete 50% to 67%

Why choose Multi-Flow for your pavement drainage?

Whether it is for new construction or addressing an existing problem, Multi-Flow is a wise choice because 1. tt does a better job, 2. it is convenient, 3. it will last, and 4. it will save money.

1. It does a better job – Illinois DOT research (1991-1994) has concluded panel shaped drain systems can collect excess water in 60% of the time. Kentucky DOT studies (1994-1997) have confirmed those findings and have documented the extended life expectancy and cost savings of well drained pavements.

Subsurface drainage systems must be able to collect water and transport water. Multi-Flow excels in both regards:


2. It is convenient – At least three factors make Multi-Flow a product that engineers, contractors and public works departments love to work with.

Shape – Because of its panel shape, Multi-Flow can be installed in a narrow trench. A rock wheel or chain trencher can cut a narrow trench for installation. The result is less excavated material to haul away, less backfill to haul in, less time spent, and of course, less expense. In repair situations, it also results in less damage to existing pavement.

Connectors – Not only are Multi-Flow connectors easy to use, there are a lot of them. Any configuration that is appropriate for a given site can be carried out using one or more of the 60 Multi-Flow connectors.

For example, airport runways demand exceptional drainage due to heavy loading, and lack of elevation. Custom manufactured connectors make it possible to install Multi-Flow in multiple layers adjacent to the runway, providing unparalleled drainage performance.

Flexibility – Multi-Flow is easily bent making it convenient to work with, suitable for making tight turns, and easily joined to connectors.


3. It will last

There are two primary reasons why Multi-Flow systems significantly outlast other drainage options.

Strength – Multi-Flow is designed to withstand heavy loads. Able to tolerate loads well in excess of 6,000 psf, Multi-Flow is not going to collapse due to heavy surface loads in shallow installations or due to earth weight in deep installations.

Longevity– The Multi-Flow system includes a heavy effective geotextile filter. This high quality fabric acts as an excellent secondary filter, keeping Multi-Flow’s flow channels clean and open. Clean coarse sand acts as a very effective primary filter. Due to its shape, Multi-Flow is easily encased in sand, assuring a long life. When placed in a 4 inch wide trench Multi-Flow is readily protected in this way. This would be difficult if not impossible using French drain methodology.

4. It will save money – A completed Multi-Flow system typically costs about half as much as a comparable French drain system. Add to that its longer life and Multi-Flow begins to look very attractive! Now factor in the cost of replacing the pavement prematurely and Multi-Flow is a system you cannot afford to live without.