A Look at Septic Tank Evolution
By Henry Vere
Sometimes things just work out right. Take, for example, the first recorded invention of a septic tank:
According to a 2003 British Broadcasting Corp. report, a Frenchman by the name of John Louis Mouras constructed a masonry tank into which was directed various household wastefrom a small dwelling in Vesoul, France, in the mid-1860s. In Mouras’s experiment, sewage overflowed from the tank to a then-standard cesspool. The tank was opened after 12 years and was found to be almost free of solids. Mouras patented his invention in 1881. Following the success of his invention, the septic tank was first introduced to the USA in 1883 and to England in 1895.
In the late 1800s the Massachusetts State Board of Health and other state health agencies had documented links between disease and poorly treated sewage. They recommended treatment of wastewater through sand filtration and land application of the sludge. Originally some homes began installing 55-gallon drums for collection of wastes, and that system eventually evolved into automatic siphoning two-chamber septic tanks made of steel with inlets and outlets as well as baffles to dissipate the energy and keep from disturbing the solids. By the mid-1950s, discharge of tank effluent from concrete tanks into gravel-lined subsurface drains became commonplace. Today at least 25% of homes use a septic system made of concrete, fiberglass, or plastic.
Long History
Shirley McNeill is the owner of McNeill Inc., of Andalusia, AL, a concrete septic tank manufacturer founded by her father, Grady McNeill. McNeill has found that new regulations are a driver in any changes it must incorporate in its tanks. Pressures for tank walls have now been increased to 4,000 psi. The State of Alabama also now requires that all the manholes must have risers on them for easier accessibility.
“But nothing truly major has changed with the manufacture of concrete septic tanks over the years,” says McNeill. “About the only thing that has changed has been the size. Through the years the tanks have gone from 500 gallons to 750, and now we’re at the 1,000-gallon size. A 1,000-gallon tank will usually handle a three-bedroom home.
“As for plastic or fiberglass septic tanks, I think most of the time they’re used when it involves an extremely difficult location, such as one in which a truck has little access or the space is simply too tight. Due to the housing market and the fact that land is getting harder and harder to get, they are now developing areas that are really not suitable for concrete septic tanks.”
In some of these areas, the ground will not percolate. More and more, McNeill finds locations in which “mound systems” or aboveground systems are being built. “You’ll have a large mound of dirt, and your septic tank system is installed in that mound of dirt.”
McNeill’s concrete tanks have been manufactured to virtually the same specifications for the past 54 years. “Mr. McNeill was the first person to ever build a pre-cast septic tank and install it in Covington County, Alabama,” adds McNeill. “The form design is basically the same over all these years; it hasn’t changed that much; nor have the ingredients: sand, water, gravel, and cement. We get our cement out of Freeport, sand out of Monroeville, and gravel out of Montgomery.”
Cement in powder form is pumped into the silo before tank construction begins. Once the water, sand, and gravel are added to that, it becomes concrete. Standard procedure is to pour the concrete one day and then break the forms away during the next day. The concrete takes from 12 to 18 hours to cure.
“I don’t see any rapid change in this business in the near term,” says McNeill, “though I’ll admit, gravel gets harder and harder to get. The local quarries are gone, and now we have to truck our gravel into our plant approximately 210 miles roundtrip. Our natural resources are really getting depleted, and with the rise in fuel costs this hurts us along with everyone else out there with a product to make and deliver.”
Years of Experience
Benny Pinckard, owner of Pinckard Vault and Marble Works Inc. of Troy, AL, uses gravel systems in the work he does installing onsite wastewater treatment systems, primarily for residential units. The concrete tanks seem to stand the test of time as far as he’s concerned. “With some of the newer products I think they haven’t been on the market long enough to make a true determination of whether or not they will stand the test of time.”
Another factor that Pinckard sees as working into the equation are the increases in prices for the plastic and fiberglass septic tanks that are rising along with petroleum prices. “This affects any products related to oil production,” says Pinckard. “Also, in the field lines for such items as perforated pipe, the cost factors are going up as well. This is becoming quite an issue.”
Pinckard used to manufacture its own concrete septic tanks, but the company found it too much of a challenge to manage all the wastewater runoff permits involved, as all of the company’s forms had been lubricated with oil products. The company’s supplier of concrete septic tanks has been McNeill Inc.
“Septic tank design has not changed a whole lot over the years, at least not what I’ve seen aside from some modifications in design,” admits Pinckard. “But the filter systems installed in the tanks these days have really been a big plus. That may be a reason behind the lack of change in septic tank design.
“When the regulations changed and they required that we install those filter systems in the tanks, that seemed to be a big factor in the longevity of the overall systems. General working conditions involving those systems have improved with the addition of these filter systems as well. But then again, those filters involve petroleum-based plastics; therefore, their costs, again, may be tied into the cost of oil.”
Risers, Manholes, and Seals
In the past, some concrete septic tanks came with concrete, poured-in-place baffles, and some did not. In the center was one manhole so the pumper could come and empty the tank if necessary. Hand-holes at the inlet and outlet were all they had for servicing. Also, they usually didn’t have any risers to the surface—perhaps because homeowners didn’t want to either see the septic tank or be reminded of where it was.
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Photo: Xerxes |
| Although septic tank design has changed little over the centuries, the improvement
of tank filters provides additional water-quality conditions in the current systems. |
“Nowadays in Rhode Island, regulations require that there be risers in both the inlet and the outlet,” says David Kalen, program manager with the New England Onsite Wastewater Training Program that is part of the Water Quality Program Cooperative Extension at the University of Rhode Island. “The center manhole is not required anymore, but instead of hand-holes, manholes are required at both the inlet and the outlet. Other jurisdictions around the country have different regulations as well.
“Now what we do, since the 1990s, is cast-in-place rubber adapters with stainless steel clamps at the inlet and outlet. This is a very flexible joint but is very watertight as well and prevents leaking out of the septic tank as well as intrusion from any groundwater.”
When innovative and alternative systems really came to fruition in Rhode Island, one of the big requirements was watertight tanks. This pushed the industry to find ways to waterproof the joints, cast-in-place rubber adapters, and cast-in-place riser adapters.
“Instead of concrete risers, mostly what we use now in Rhode Island are cast-in-place riser adapters for I&A systems,” says Kalen. “So the pre-caster simply pours in place a plastic ring in which the installer can glue a PVC riser to. This results in a very watertight and gastight riser.”
The lid has a neoprene rubber gasket so once it’s bolted in place it is completely gastight as well. The service provider can unbolt the lids on the inlet and outlet manholes—typically four bolts to unscrew.
In Rhode Island, fiberglass septic tanks are also approved for use. With many of the state’s communities and their small home lots, even a mini-excavator cannot access the land. Kalen says that six workers can easily lift a fiberglass tank into place by hand.
“For some of our state’s pre-existing lots with narrow passageways to the backyard, the application of a fiberglass septic tank is a great fit,” says Kalen. “Also, in a place like Block Island, where the means of getting there is by ferry, fiberglass tanks are more compact and lighter for the ride there.”
Durability for Tight Spots
Ease of handling, lightness of weight, and strength all make fiberglass a good fit for tight spots. As with plastic, the cost of fiberglass tanks is tied in somewhat with the price and availability of petroleum.
G&B Fiberglass Products Co. Inc. of Banning, CA, has been producing fiberglass tanks since 1973. For residential systems tanks run from 1,000 to 1,500 gallons in size.
“I’ve had pumpers, those who clean the tanks out periodically, tell me that the fiberglass tanks look fine inside, even those tanks which have been in the ground for quite a long time,” says Steve Primack, owner of G&B Fiberglass Products Co. Inc. “They see little corrosion and report that the tanks clean out quite well. It’s telling too that all the fuel tanks for gas stations currently being installed in southern California are made of fiberglass.”
Primack sees changes coming mainly in the area of increasing sizes of the tanks. “Where a 1,000-gallon tank was once adequate, now a 1,200-gallon tank is used,” says Primack. “This trend is more or less code-driven as far as sales go.
“As far as the specifications of the tanks, that’s pretty much stayed the same. It used to be sizing of tanks went by bedrooms and baths. Now here in California things seem to be driven by fixture units so that when a certain number of fixture units are specified, this corresponds with a septic tank of a certain gallon size. I’m uncertain if that’s a new trend, but it is something which has been adhered to more rigidly of late.”
G&B Fiberglass Products Co. Inc. mainly supplies tanks to California and southwestern states such as Arizona. It has also shipped its tanks to Hawaii. The two halves of the tanks are assembled once they reach Hawaii. Because housing is tight in urban areas of that state, the lightweight fiberglass is easy to place in hard-to-get-to places. It can be carried in by hand.
In its home state the company is currently hoping the real estate market strengthens in its area to boost septic sales. Primack feels that eventually things will turn around.
Keeping It Working
Art Boelke, a sales representative in the Carolinas and Tennessee for a fiberglass tank manufacturer, sees the technology with septic tanks moving away from traditional material of construction to non-permeable one-piece watertight materials such as fiberglass. “This has helped our business, and we continue to sell more tanks built from fiberglass for these applications,” says Boelke.
“This is simply due to the improvement in technology. When you have porous two-piece tanks containing septage, you are exposing the microorganism process to an influx of ground water that can reduce the bacterial digestion of waste, and you are also exposed to the possibility of leakage of septic material into the ground.
“By going to a non-porous watertight single structure you get a strong tank, and the process is not as exposed to these negative effects. We have taken material and structural technology from years of being the nation’s number-one-selling tank in the petroleum industry for storing gasoline to the wastewater industry, providing flexibility and technology as an alternative to traditional tankage.
The other thing affecting this market is the lack of federal US government funds to construct municipal waste treatment plants and expansions for municipalities. “The feds don’t have the funds to do that anymore,” says Boelke. “Therefore, many states, such as Tennessee, for instance, are now permitting onsite treatment for new commercial and residential developments.”
There are new technologies as well as new companies that design, manufacture, install, and monitor these systems for new residential and commercial developments. These systems are highly efficient and very cost-effective. Developers are becoming increasingly knowledgeable in these onsite systems.
Onsite systems are a good way to accomplish waste treatment because fiberglass tanks offer more flexibility than the traditional tanks, according to Boelke. Fiberglass tanks are lighter and less expensive in the larger tank sizes and offer many accessories to fit the various technologies and applications.
“Instead of having a municipal system for a whole town, we’re seeing that it’s much more economical for the developers to do an onsite treatment system,” says Boelke. “Some of the old technology is being refined and brought back, and it’s a whole lot less expensive than a new waste treatment plant, and it works very well.”
Boelke says he heard of a city that is being fined daily by the state because it is dumping excessive waste into creeks. “The opinion is that it’s cheaper for them to pay the fine than to build big new municipal plants,” says Boelke. “That’s not how it should be, and onsite systems will be the future’s answer.”
Non-porous Tanks
Polylok Inc., a Wallingford, CT–based company, manufactures several products for septic tanks in the onsite wastewater treatment industry, in addition to two other industries that it services, those of pre-cast concrete and the drainage industry. The company started in 1984 as a pre-cast concrete company. It saw the need for seals in the septic tank industry, and from there it evolved into a company that comes out with several new products yearly.
It has septic tank risers, covers, seals, and gaskets for tanks; devices to control the distribution to drain fields; and devices for pressure systems. “We basically supply anything for the onsite market,” says Patrick Mulhall, Polylok Inc.’s vice president of sales. “We either have the accessories or will have products coming out to meet those needs.”
Typically it sells to the manufacturers of concrete, plastic, or fiberglass tanks as well as plumbing wholesale supply houses throughout the US. The company, on average, comes out with seven new products per year. Its filters and other products have all been extensively and independently tested.
“But the onsite wastewater industry is growing,” says Mulhall. “As more and more states and provinces are requiring the use of effluent filters, this really comes into play.
“Ontario, for example, just brought out a requirement for mandatory effluent filters on its septic systems as well as septic tank risers to grade. Those are two products we sell quite a few of.”
In the United States more and more states require that an effluent filter be used and also that the tanks have risers to grade so such tanks can easily be serviced, according to Mulhall. Many times Polylok Inc. helps with the process of accomplishing the new rule changes.
“Everyone ends up having a voice or say in some of these rules,” adds Mulhall. “Proposed rules often contain language which ends up changing several ways before being enacted and then finally made into law.”
For the future, Mulhall sees onsite systems more and more as the standard model. “Not everyone can be hooked up to the sewer. It’s expensive. Also, if everyone was hooked up, you simply would not be able to afford the cost of running and maintaining everything. The cost-benefit perceived to be there with municipal systems has turned out simply not to be there; it’s too costly.”
Large Tank Requirements
Fiberglass tanks have grown in popularity and usage to fill the significant onsite industry market for tanks in large-flow, large-capacity systems in commercial and industrial applications. Fiberglass underground storage tanks were first developed in the 1960s as a solution to rusting/leaking steel storage tanks. Fiberglass is a common term used for a resin-based laminate reinforced with glass fibers. Fiberglass, it may be noted, is often used as reinforcement in concrete as well.
When the topic of septic tanks is discussed, frequently the focus is on the smaller residential tanks, 1,000 gallons to 1,500 gallons in size, according to Tom Tietjen, vice president of sales and marketing with the Xerxes Corp. of Minneapolis, MN. Xerxes is among the largest manufacturers of fiberglass tanks in the world. “Fiberglass tanks are in service for all different types of uses,” says Tietjen. “If you filled your vehicle with gas this morning, you most likely pumped that fuel out of a fiberglass tank.”
Tietjen points out that fiberglass tanks are especially effective for residential cluster treatment systems. Instead of the homes each handling the waste treatment on their lots with tanks and drain fields, the waste may be routed to a neighborhood plant. For a piece of property with no municipal connections, a developer can place a small treatment plant in the corner of his development to treat all the wastewater generated.
Industry applications for large-flow systems include the use of fiberglass tanks for hotels, casinos, truck stops, or any such establishments outside the reach of municipal sewer lines. ”All of these types of commercial facilities also need treatment processes,” adds Tietjen. “This is an especially large and growing market segment; fiberglass tanks are able to be produced in one of our four plants and shipped directly to job sites without field assembly necessary, which would be required for other types of tanks this large.
“Because fiberglass tanks can be factory-manufactured and delivered in sizes up to 65,000 gallons, they provide the perfect solution. A one-piece fiberglass tank can be delivered to the job site ready for installation."
The larger tanks are well suited for the increased flow rates of commercial systems, such as a hotel or casino, handling much more than a residential system and single tank would. Where a three-bedroom home may have a 1,500-gallon septic tank, a restaurant or hotel might have a number of 20,000-gallon to 30,000-gallon tanks as part of the treatment process that has become much more sophisticated as well.
“These types of systems typically don’t run into a traditional drain field,” says Tietjen. “They often have a much more sophisticated treatment process, often requiring multiple vessels including recirculation tanks.”
Tietjen also emphasizes that fiberglass tanks are especially well suited for avoiding leaks into the environment or from having groundwater from the outside leak into them. “These are the same tanks used to store a variety of hazardous materials such as gasoline storage, where no amount of leakage is acceptable. Also, they are so durable and long-lasting that they can outlive the commercial operation where they were installed.”
Henry Vere writes on scientific subjects.
OW- November/December 2007
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