IMAGINE YOU’RE walking along a street filled with pastry shops, bakeries and restaurants. Delightfully tantalizing odors fill the air as you stroll along the boulevard; your senses sharpen as you “taste” the air. Unable to resist temptation any longer, you follow your nose to indulge in a treat or meal.
Now, imagine you’re a tree root winding your way through the soil. You are a feeder root (the meristem) that grows outward — one cell at a time. Any opportunity to gain nutrients and moisture gain your immediate attention.
Sewer lines buried below grade tend to collect moisture on their exterior when warm water flows through the cooler surrounding layer of soil. Violating the basic tenet that water doesn’t flow uphill, capillary attraction between closely packed soil particles wicks up the moisture, creating a vertical vapor trail. As the feeder root, your responsibility to ensure survival of the tree dictates your growth downward to the sewer line.
If there is a crack, fissure or leak from a joint, that vapor trail becomes a dinner bell not unlike your stroll along that concession-lined boulevard. Tree roots can’t resist the vapor trail and trouble is on the way for that homeowner, business or municipal sewer system.
For trees and plants with a taproot system, their root zone can extend more than twice the distance that they are tall. You’ve seen that firsthand with customers’ tree root-infested lateral connections where only the neighbors across the street have trees. In times of drought, tree roots wander much farther.
Roots don’t like to have continuously wet feet and most species can’t survive if permanently submerged. Consequently, you’ll see two distinctly different patterns of root growth in municipal mains, which have constant flow, and private lines, which have intermittent flow.
Sewer mains tend to have roots enter the top of their invert with the roots extending downward until they come in contact with the sewage flow. Once there, they branch out with thousands of tendrils, forming densely packed root bundles that float along the surface, all the while collecting nutrients and moisture while enjoying a perfect growth environment.
Individual sewer lines see intermittent flow, so there we see tree roots taking any opportunistic opening to infiltrate and collect nutrients.
Willow trees don’t mind having wet feet and are one of the more difficult root infestations to manage. Willow trees can absorb many gallons of water per day and, as a result, may go on for years absorbing water and nutrients before causing a backup within the home. As a result, we’ve seen infestations that defied cleaning with root-cutting sewer cleaning equipment. Once excavated, the root bundles completely packed the line for several yards. Once the piping has been broken away, those tightly packed roots retain the exact shape of the line.
The materials used in sewer lines have changed as materials became available: Terracotta with cement lined joints gave way to Orangeburg bituminous fiber piping; cast iron with oakum and lead joints gave way to rubber gasketed joints with claims of better root resistance, which gave way to no-hub pipe and couplings; and PVC plastic piping commanded attention with both glue or gasketed joints being permitted in various municipalities.
No doubt PVC piping that is correctly installed with solvent-weld joints offers an almost impenetrable fortress against intrusive tree roots, but given the forces you see where sidewalks and roadways are concerned, I have little doubt that when feeder roots grow to become substantially sized root structures, they will have the ability to lift and crush virtually any man-made piping material.
Mechanical pipe cleaning equipment hasn’t changed much over time. We continue to auger these lines with root-cutting heads designed to rip, tear and cut away most of the root structure. This, in turn, stimulates root growth. Lots of new feeder roots can branch from a single root, resembling fine hair. Once you clear a customer’s line that has roots, you can pretty much assume he will need annual service and offer him a preventive maintenance contract. Being able to schedule the sewer cleaning call gives all involved time to plan the trip during “normal” business hours.
Sewer line videotaping is becoming more and more popular as the equipment continues to improve. We had an opportunity for a live demonstration of General Pipe Cleaner’s Gen-Eye sewer-line video equipment a few weeks ago while chasing down an underground sewage leak that was infiltrating a neighboring basement. Not only was the color image crystal clear, the camera head emitted a signal that can be followed from above the floor with a locator. The locator also gives a fairly precise indication of the line’s depth.
Next up for consideration will be the Ridge Tool Co. Ridgid SeeSnake line of equipment. With the numerous calls we’ve had for video inspections, this will be the year for investing in the equipment.
Dave Yates owns F.W. Behler Inc., a contracting company in York, Pa. He can be reached by phone at 717/843-4920 or by e-mail at [email protected].
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