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The pitfalls of breaking through concrete: Grinder pump systems as an alternative for commercial establishments

By Phil Warren, SFA Saniflo Canada

Construction crews often run into challenges when it comes to breaking the floor or concrete slab to install sanitary drains. Architects should be mindful of these challenges when working with plumbing or mechanical contractors and specifying plumbing systems.

Many older hotel buildings are constructed with concrete slabs that contain post-tension cables. Core-drilling them to install drainage could compromise a building’s integrity.

For such applications, an above-floor pump system is an effective, cost-efficient alternative to time-consuming, labour-intensive of trenching. Grinder pumps systems offer a solution of time saving convenience and cost-saving benefits.

Unfortunately, when confronted with the above scenario, too many plumbing installers fail to consider the above-floor option, probably because they haven’t yet tried it. But even if you don’t know much about above-floor pump technology, we would still urge you not to discount the pitfalls of busting through concrete floors.

Below we enumerate the most important of those hazards. Before proceeding on your next floor-busting project, you may want to sit down with the general contractor, the plumber      and your customer to discuss each of these potential problems in depth… on your way to considering an alternative approach.

Red Flags to Remember

Cutting concrete undermines structural integrity: Any time even the most careful contractor cuts into a slab, the foundational integrity of the building decreases — no matter how close to a perfect cut is made. The installer may be able to patch the hole created well enough to eliminate any aesthetic objections. But is the floor as solid as it was before the cut?

We would bet not — especially if the installer fails to rebuild the floor correctly using rebar, wire mesh and a better grade of concrete. And if the building sits on ground that’s less than solid, such as sand, it may begin to settle differently after the cut.

In a multi-floor building, cutting into a slab on the second, third, fourth levels to run plumbing beneath the floor would be a huge no-no. That’s why commercial-renovation projects that require additional plumbing will typically use external soil stacks, putting the external plumbing on the outside of the building.

Think about it: If you shouldn’t cut into any of the upper levels of a building, why would you think you could safely cut into the first-level — the slab on which everything else sits?

Cutting concrete is unpredictable: Plumbing and mechanical contractors don’t always know the true depth of the concrete, whether it sits on rocks or a ledge, or whether it contains rebar or tension cables or in a heated floor. An installer can cause major damage if they accidentally cut into any above mentioned below floor options. Professional contractors understand this hazard and never begin cutting without first using an x-ray machine to determine the positioning of the cables, rebar or if there is a heated floor.

But even then, the slab was most likely designed to use a certain number of cables with a certain amount of concrete. If the installer begins removing chunks of concrete, those tension wires may begin pulling in a different direction, creating integrity problems and causing delays and extra expense.

Cutting concrete is seldom, if ever, perfect: A professional contractor may try as hard as they can to cut a perfect circle, square or rectangle into a floor for burying a sewage ejector and its waste-storage basin — but no way. That “perfect” shape will inevitably crack around the edges and fray outward in unintended directions, often well beyond the hole the contractor is digging. And once a stress crack is created, how far down does it extend into the slab, footing or into the walls?

Cutting concrete can creates leaks and seepage: Once a stress crack is generated, radon and ground-water penetration are major issues, with the latter bringing unwanted moisture and mold problems as well. You don’t need a major flood to trigger these hazards. A higher-than-usual water table because of extended wet weather, such as in the spring, could be the culprit. This can also cause an install issue when installing the ejector pit.

Even if the cracks and seepage are not large enough to jeopardize the foundation, enough wetness could infiltrate to ruin walls, floors and furnishings in a finished living area — including that beautiful new bathroom or restroom that necessitated digging through the concrete in the first place.

Cost factors: Last, but certainly not least, there’s the problem we mentioned at the outset of this article, the one that often proves to be the biggest deal-breaker of all: cost. The actual expense of cutting concrete depends on the size and complexity of the job, as well as local labour availability and rates. In some parts of the country, the per-foot rate may be $1,000 or more.

Seeing these costs, some plumbers outsource the work and are content to make little or no markup on their sub’s charges. Others, preferring to keep the job in-house, absorb the time and cost of renting the cutting and hammering tools and lugging them on and off the job site; or, if they choose to buy, the cost of maintaining and replacing these tools, as well as depreciation.

Meanwhile, with above-floor pump system, creating a new bathroom or kitchen where none exists usually takes a day, maybe two at most, to install the basic plumbing. Go the conventional, busting-through-concrete route and the installer’s crew will be on the job triple or quadruple that amount of time and likely more.

Grinder Pump Systems as an Alternative

No doubt, installing conventional plumbing requires major construction. In fact, based on the pitfalls shared above, it could be even more expensive and complicated if your customer’s space is in an older building or a high-rise, where it’s difficult to change the plumbing infrastructure.

Let’s take a closer look at grinder pump systems as an effective, cost-efficient alternative to trenching.

Pre-assembled grinding pump systems are capable of discharging wastewater from multiple fixtures in different locations. No matter how big your project is, for industrial, commercial or residential applications, above or below ground, one or two HP motors, a grinder pump offers a cost-effective alternative to trenching.

Consider Saniflo’s Sanicubic range of pre-assembled, simplex (one pump) and duplex (two pumps) systems. The Sanicubic Vortex Series features a vortex-type impeller that delivers clog-free handling of solids up to two inches in diameter. The new series is engineered for highly demanding, rugged-duty applications that involve much larger or harder objects than what is typically flushed down a toilet.

Sanicubic 2 VX

The Sanicubic 2 VX is able to discharge the waste up to 36 feet vertically using a 2-inch diameter pipe; or up to 20 feet when discharging through a 4″ pipe. Featuring easily removable circular panels on top, the unit’s IP68 enclosure permits ready access to every major component inside. The result is easier and much cleaner servicing than conventional, below-floor systems whose maintenance can entail wading into a pit full of waste.

The Sanicubic 2 VX employs an internal air pressure system for automatically cycling the unit on and off.  This technology is far more precise than a conventional float mechanism because the system is equipped with a failproof air pressure sensing mechanism system.

Three pressure switches are installed on the system’s own internal dip tube, in order to detect the water level inside the enclosure. The unit also comes equipped with a wired control panel, as well as an external audible and visual LED indicator alarm in the event that a pump experiences overload or ceases to operate.

As noted, the Sanicubic 2VX uses a specially designed pump impeller to create a vortex action as the effluent enters the grinder pump system enclosure. This technology keeps solids away from the impeller as it turns, pushing waste rapidly through the pump and to the discharge pipe. In doing so, the possibility of clogging is substantially reduced.

Next time you have a project that potentially involves busting through a concrete floor to run piping or bury an ejector pump, we hope you’ll take a few minutes to recall the red flags associated with that strategy and the far more convenient alternative. Why favour the Old School Way when there’s an easier, more effective and less expensive alternative that will leave any building owner much happier and project costs significantly lower.

About the author: Phil Warren, Managing Director and National Sales Manager at SFA Saniflo Canada, brings more than 20 years of industry experience to his position. You can reach him at [email protected].