The Clenz mission is simple: helping New Zealand keep our waterways clean. We believe our pristine waterways are a precious resource, and we believe we have a responsibility to care and protect them for future generations. An important part of protecting these waterways for many businesses is having effective and reliable wastewater solutions, particularly passive grease traps designed to capture FOG (Fats, Oils, and Grease) before they enter the public wastewater network.
When selecting a grease trap, do you know whether you are truly investing in a solution that will last and perform reliably? Or are you choosing a grease trap that might fail prematurely, causing headaches, environmental risks, and unexpected costs down the line?
The Importance of Structure
We often don’t consider structural integrity in our daily lives which include our homes to the bridges we cross. A structural system is essentially the method of assembling elements so they support and transmit applied loads safely without exceeding their limits. When we think about a passive grease trap, especially one installed underground, its structure is an critical consideration. These tanks aren't just passive containers; they are building elements that must withstand significant and complex loads from the surrounding soil, groundwater (hydrostatic pressure), and surface traffic for decades.
Looking at Industry Weaknesses
Unfortunately, our industry sometimes sees suppliers in the market with products that have had little thought beyond a basic "fit for purpose" assumption. This can lead to issues with poorly designed units. These two common examples reveal significant weaknesses in such products:
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Unlined Concrete Grease Traps: These have been a traditional choice, but they have a fundamental flaw: concrete is porous. Captured fatty acids break down over time, which often results in mildly acidic conditions within the trap. This acidity leads to the dissolution and erosion of the lime in the concrete and corrosion of the steel reinforcement, causing the material to break down. Industry guidelines even recommend using a tap testing rod to check for eroded or holed sections in concrete traps, confirming that internal corrosion is a known issue. Considering the Building Code requires facilities for industrial liquid waste storage to be constructed from materials "impervious both to the waste... and to water," this raises a the question: Do unlined concrete traps, which absorb grease and corrode, truly meet the building code requirement? Concrete units are expected to fail, and it's a matter of when, not if, typically succumbing to corrosion after 10 to 20 years.
- Flat-Walled Tanks: Some flat-walled tanks available have multiple issues. Some do not have the material thickness to handle constant heat above 65 degrees, potentially leading to sagging. Some even rely on backfill (like a 4-to-1 sand and cement mixture) to hold their structure and integrity underground. If the upper surfaces of these tanks are detailed as non-load bearing, the structural capacity of the side walls becomes questionable. The question is rightly posed: Should anyone be able to build a tank and call it a trade waste device without appropriate engineering?
Why Simple Calculations Aren't Enough: The Need for Engineered Design
While above-ground round tanks might allow for relatively simple calculations to determine wall thickness, underground grease traps are vastly different. They experience complex stresses coming from different directions. It is impossible to calculate all these stresses and displacements using a calculator.
This is where Finite Element Analysis (FEA) comes in. FEA is a sophisticated computer-based method to accurately design products like underground tanks. They can be used to predict their long-term performance. It accounts for the intricate ways materials behave under various loads. A new Australian Standard explicitly requires the structural design of in-ground grease arrestors to be performed by a qualified professional engineer using FEA. This analysis must consider structural integrity during handling, transport, and installation, as well as hydrostatic uplift, lateral loads, and top loads. This standard sets a design serviceable life of 20 years for passive grease arrestors, determined by FEA.
How Independent Certification & Testing Helps
Currently, there is no specific applicable general or national standard specifically for grease traps in New Zealand. Currently, the most relevant certification available is AS/NZS 1546.1, which covers on-site domestic wastewater treatment units like septic tanks and holding wells. This standard is important because it references desired performance in the Building Code.
The Building Code's functional requirement B1.2 states that buildings, building elements, and site work must withstand the loads they are likely to experience throughout their lives. Furthermore, B1.3.1 requires them to have a low probability of rupturing, becoming unstable, losing equilibrium, or collapsing. AS/NZS 1546.1 certification aligns with these crucial safety and performance requirements.
Achieving this certification is a very involved process. It includes a detailed design and testing process as well as testing products to failure and then redesigning them based on the results. It also requires careful analysis of the short-term versus long-term performance of materials like polymers, understanding how they behave under stress over time.
Certification is an important step in assuring that customers continue to receive the very best in quality through an independently certified and measure process.
The benefits to working with grease trap certification include
- Systems and process performance controls
- Products must be tracked and tested via batch certification
- Planned and implemented staff training and development
- Independently audited manufacturing and processing systems means the highest quality products for end-to-end solutions.
There is no hiding of any steps, there is no smoke and mirrors or false statements, everything is reviewed in detail and the product is independently certified.
Polyethylene: A Material Engineered for Longevity
Materials play a crucial role in structural integrity and longevity. Unlike porous concrete, polyethylene (HDPE) is a material well-suited for grease traps. It is chemically inert, non-porous, and UV stabilised. This makes it highly durable and acid-resistant, unaffected by the corrosive acids, bases, and salts found in grease traps, as well as bacteria, fungi, or aggressive soils. It doesn't require additional acid-resistant coatings that steel and concrete units often need.
Polyethylene is highly durable against dents, cracks, or breaks. Importantly, it has a projected life span of over 50 years. This stands in stark contrast to concrete units, which are expected to need replacement after 10-20 years due to corrosion. Choosing a polyethylene unit designed and manufactured to high standards means selecting a product built to last for decades.
Furthermore, products manufactured from polyethylene are significantly lightweight compared to concrete equivalents (e.g., a 2,000-gallon concrete trap weighs ~21,250 lbs, while an HDPE equivalent is ~1,350 lbs). This makes them easy to transport and install, considerably reducing installation and transport costs and avoiding the need for heavy equipment like cranes.
Investing in Long-Term Value
While concrete units might have a lower upfront cost, this is a classic example of "stepping over a dollar to get a dime". Considering the total installed cost over the lifetime of the unit reveals the true value. A concrete unit that fails after 10-20 years requires significant expense for replacement, including the costly proper disposal of hazardous material and potential loss of business revenue during downtime. An engineered, certified polyethylene unit offers a much larger advantage – these units have a lifespan of up to 50 years!
Our Commitment to Quality and the Environment
At Clenz, we are committed to providing quality, long-lasting wastewater solutions that are sustainable and environmentally-friendly. By choosing a passive grease trap you are investing in a product designed with emission reduction strategies:
- Energy Efficiency: We've upgraded to state-of-the-art machinery that consumes 40% less energy than traditional equipment.
- Renewable Power: Our facilities are transitioning to 100% solar and wind power, drastically reducing our carbon footprint.
- Waste Reduction: Innovative mould designs and precision control have cut material waste by 30%.
- Recyclable: Halgan Grease Traps are fully recyclable, feeding back into our production cycle for true circularity.
With the help of Clenz’ professional and friendly team you can make an informed decision that suits your building or development project.
Contact Clenz today for more information including a no obligation quote.
