Serious about Septic Tanks

Inconsistent enforcement and bad apples spoil the bunch.

By Dean A. Frank, P.E.
Dean Frank is Director of Technical Services at NPCA.

For a long time now, septic tanks have been seen as the bread and butter of the precast concrete industry. However, unless things change soon, this may no longer hold true.

There is a perception among some in the regulatory and onsite wastewater communities that it is impossible to produce a watertight, structurally sound precast concrete septic tank. However, as most of you know, this simply is not true. You also know that a properly manufactured, installed and maintained precast concrete septic tank is the best solution for onsite wastewater treatment. Unfortunately, the misperceptions in the regulatory and onsite wastewater communities are the product of a few bad apples that have damaged the reputation of the industry. These misperceptions are further compounded because regulators have not in the past, nor do they now, consistently specify and enforce conformance to appropriate standards.

Making this situation more urgent is the fact that manufacturers of fiberglass and polyethylene tanks are eager to supply tanks to those who have lost faith in precast concrete tanks. So, it’s time to get serious about septic tanks.

What’s important?
Four things are essential to the proper function of a septic tank. The tank must be watertight, it must be structurally capable of withstanding the loads it will encounter when handled and installed, it must be installed correctly and it must be maintained properly. Tank producers are generally in control of the first two criteria (unless of course the installer happens to damage the tank during installation), and they should try to influence the second two.

In the past, the watertightness issue was commonly misunderstood, although people are gradually becoming mindful that tanks must be watertight. The first problem is leakage out of the tank. Some people wonder why leakage is such a big deal considering that the tank contents are emptied into the drainfield, maybe only a short distance away. The answer is because the tank does not function properly if it leaks. If the liquid level is lowered within the tank, the scum layer lowers with it, which can then clog any number of components downstream from the tank and cause the system to fail when the liquid level rises again.

Wastewater leaking from the tank cannot be treated properly and can short-circuit into the groundwater prematurely. Septic tanks are pretreatment devices. The drainfield is a specially designed gravel and soil system that contains bacteria that provides final treatment of the effluent and allows it to drain into the ground in a designated location and in a controlled manner. Thus, since the soil in the drainfield provides the final treatment of the wastewater, wastewater that doesn’t reach the drain field in the first place doesn’t receive proper treatment.

The second problem associated with watertightness is infiltration of groundwater into the tank. If infiltration occurs, the tank can get overloaded. Solids that are intended to remain in the tank can be inadvertently washed into and clog downstream components. These solids and/or excess water can cause premature failure of the drainfield.

It should be obvious why structural integrity is important. The ability of a tank to support itself and the loads imposed on it not only are important for safety reasons but for the watertightness aspect of the tank as well. Septic tanks are no longer considered a temporary solution to wastewater treatment until sanitary sewer lines can be installed. These tanks should last as long as the homes or businesses they support.

Changes are coming – like it or not
Producers of precast concrete septic tanks are at a crossroads. Regulations are looming that will require watertightness and adequate structural capacity. It is only a matter of time before these regulations will affect all producers of precast concrete septic tanks.

The precast concrete industry has already taken steps to help ensure that tanks perform as required. In 1998, the National Precast Concrete Association partnered with the National Onsite Wastewater Recycling Association (NOWRA) to produce the “Septic Tank Manufacturing Best Practices Manual” and a companion video that highlights the necessary steps for producing and installing watertight, structurally sound septic tanks. Although there is some debate by a few tank producers about its suggested manufacturing practices, the manual is highly regarded for promoting the use of precast and helping precast concrete remain the preferred tank material. Since publication, many regulatory agencies have modeled their regulations after this best practices manual, which subsequently promotes – rather than denies – the use of precast concrete septic tanks in these jurisdictions. Presumably many more regulatory agencies will follow in this regard.

What should tank manufacturers do?
Precast concrete septic tank manufacturers can do three things to help the industry thrive:

Produce. Producing a good-quality, watertight, structurally sound, durable tank is the first step in the process of helping the industry thrive. The fact is that the majority of producers are quality conscious, but they must compete with the minority who are not.

Verifying watertightness and structural capacity is the next step. Tanks are typically designed either by engineering calculations or by performance testing of the final product. If a producer does not have documentation of either of these, he should seriously consider getting it. Many resources and companies are available to help with both design and testing.

Further, discussions within the regulatory community indicate the possibility of widespread requirements for watertightness testing of tanks after they have been installed. Wouldn’t it be best to know that a tank is capable of passing such a test before it leaves the plant, rather than after it has been installed?

Promote. Manufacturers of precast concrete septic tanks should promote the use of standards that result in tanks that perform correctly and remain serviceable for the expected lifetime of the residence(s) or commercial projects that the tanks support. These standards should be promoted to regulators so that all manufacturers, regardless of the material composition of their tanks, must meet the same minimum level of performance criteria.

It is critical that these standards be uniformly and consistently specified and enforced by regulators. However, this is not likely because regulators may not be able to enforce these standards on their own. Thus, the industry must police itself. It’s far better for the precast concrete industry do this policing rather than some other entity – possibly one that is not favorable to precast.

Standards should also be promoted to other precast tank manufacturers as well as applied to manufacturers of tanks made of other materials. This would keep precast concrete septic tank manufacturers from competing among themselves and meet the needs of the regulators and end users, and keep competing materials from continuing to gain market share and ultimately eliminate the use of precast concrete for septic tanks.

Provide. If you were to buy a product from any of the big home-improvement stores, chances are it would come with installation and operating instructions. Likewise, the performance of a septic tank is heavily dependent on proper installation and operation, so it would be best to provide this information to the installer and the end user. At a minimum, installation instructions should include: handling, bedding and setting requirements; and an outline of the conditions for which the tank was designed, including the maximum depth of burial and vehicular loading. The end user should be educated on the proper use and maintenance of the entire system. Although a tank producer typically is not directly in control of installation and operation, instructions for these tasks would influence the installer and owner and potentially help the tank perform properly and reduce the number of callbacks the producer receives.

We’re all in this together
Issues regarding septic tanks affect more than just the manufacturers and components. They affect both the health and finances of the homeowners and businesses – and even their neighbors – that rely on their proper function. As populations grow and expand into unsewered areas, this issue will continue to grow and expand with it.

As an industry we must work together to set standards for the proper production, installation, operation and maintenance of precast concrete septic tanks. Failure to do so will adversely affect the future of this important business. So, it’s time to get serious about septic tanks.