Tanksmart offers the best qualities of concrete and fiberglass (or poly) products in one, and addresses the most significant limitations of each respective product in the process. The result is a tank solution that is really the Best Of Both.

The Limitations of Traditional Concrete:

Traditional cast-in-place or pre-cast concrete tanks have long been the chosen product because concrete is usually readily available and in most cases it provides a robust structure at a reasonable cost. The combination of cement, water and aggregates has been used for centuries to construct some of the world's most amazing structures, so why are concrete tanks challenged with interior corrosion and deterioration? Most often it's due to an improper mix design or a combination of improper mix design, poor placement process, lack of proper reinforcing and corrosive tank contents. Soil-borne sulphates can cause significant damage to concrete if it has not been properly designed at the mixing stage. Inside the tank, repeated freeze/thaw cycles, and constant exposure to chemicals found in the contents can eventually cause deterioration. A poor mix design or improper placing process can result in an inferior product, making it prone to cracks, leaks or spalling and thereby allowing tree roots to enter, harmful wastewater to leak out, or allowing contamination of the potable water inside the tank.

Liners are available in a variety of materials and applications, but they are typically costly and adhesion and maintenance of the liners is often a problem.

Pre-cast tanks are typically made of multiple components and as such have exposed and vulnerable cold joints. While those joints are typically sealed with a gasket material of some kind, studies have shown those joints to be surprisingly vulnerable. The manufacturers naturally build the thinnest tank wall possible in order to keep shipping weights to a minimum and make the best of their tank-weight/tank-volume ratios, and still meet the minimum requirements of local authorities. In spite of this effort the transportation and placement of pre-cast concrete can become costly due to the extreme weight of the tanks. The limited size options are also a result of the extreme weight of concrete.

Furthermore, the compromise in tank wall thickness usually mandates overhead vehicle load restrictions.

Generally, concrete tanks larger than 3500 (+-) gallons have to be constructed onsite with traditional, flat wall and flat top forming systems, (this can be a time consuming and labor intensive process) or with pre-cast panels (this process typically has a large number of vulnerable cold joints).

The Limitations of Traditional Fiberglass:

Over the past 50 years or so fiberglass tanks have proven that their non-corrosive characteristics are outstanding for underground applications and when properly installed they have demonstrated tremendous ability to last. This can lead to the assumption that conventional fiberglass tanks are structurally strong, but according to Public Works and Government services of Canada, as much as 80% of the structural value of an underground fiberglass tank comes from the use of proper backfill material. Even with the use of the specified (expensive and sometimes unavailable) fill material (usually pea gravel), burial depth is normally limited to about 7' of overburden. For approximately 30% to 40% more in tank cost, burial depths can be increased up to as much as 10' of overburden. In situations where the tank will be positioned under areas subject to vehicle traffic, special considerations must be given to the burial depth, type and depth of overburden, and adequately reinforced driving surfaces must be provided. Some manufacturers do not recommend any kind of vehicle traffic above the tank location and will typically void warranty if the tank incurs damage from traffic. If traffic is permitted, structural limitations dictate vehicle weight restrictions.

In the instance of a wet hole, deadman anchors and tie-down straps are also required, and ballasting the tank during installation is recommended. Typically, the anchor systems consist of concrete blocks which are placed into the excavation alongside the tank and then turnbuckles and straps (either fiberglass or steel) are used to hold the tank down in the event that the excavation should take on water. The reason pea gravel is the desired fill material is because it is free of fines and is a very stable material. It essentially creates a cast around the tank, but the inherent problem with it is that ground water and surface run-off naturally fill the excavation because the absence of fines in the pea gravel provides the path of least resistance allowing water to surround the tank. The presence of ground water makes the exposed steel fasteners and anchoring systems vulnerable to rust. If the tank is emptied for whatever reason in wet circumstances, the hydraulic uplift on the tank is enormous, and subsequent stress points at the locations of the tie-downs can cause tank deflection increasing the risk of tank wall or nozzle failure, or some part of the tie-down system becomes over-loaded, leading to failure of the anchoring system and allowing the tank to pop up through the ground surface. An alternative is to sacrifice 30% of the functional tank volume by leaving it at least 30% full at all times to provide a consistent ballast.

The use of recommended fill material is critical to the long-term success of the installation. The amount of pea gravel required is subject to the size of excavation required to meet OHS (Occupational Health and Safety) compliance. OHS requires a slope of 1:1 on the excavation embankment in stable soil conditions, and as much as 1:2 (or as required to be made safe) in unstable soil conditions. Most tank manufacturers will offer some guidance on minimum required amounts, but most often the calculations are based on vertically cut banks and not on OHS compliant excavation practices. In order to properly place the backfill material there must be provisions made for personnel to enter the excavation. The cost (and sometimes availability) of the correct type and amount of fill material is often prohibitive. If proper fill material is not used, the warranty will be void, the structural integrity of the tank is seriously compromised and tank failure is almost certain.

Additional load and haul costs are typically associated with fiberglass tank installations as the originally excavated material has to be dealt with in some way, and significant amounts of fill need to be brought onto the site.

The Limitations of Traditional Poly:

While some great mamufactured products are readily available in  smaller volume tanks, traditional poly tanks (sized 2000 gallons plus) simply are not designed to withstand overburden without being crushed.

The Tanksmart Advantage:

The Tanksmart solution addresses all of these limitations by using quality fiberglass and poly components as a liner on the inside of a steel reinforced shotcrete tank structure that is typically 1 ½” to 3” thicker than most pre-cast tanks. The most significant benefits of fiberglass or poly are the rust-proof, non-corrosive properties which provide the most desirable tank interior on the market, and the steel reinforced shotcrete tank provides the most exceptional monolithic structure in the tank industry.

The use of shotcrete increases the value of concrete use because shotcrete is spray applied concrete, and as such it has some qualities that give it significant value in a tank application. Because shotcrete uses a considerably drier mix, and the water-cementious material ratio is lower than that of poured concrete, it is known to cure up to 50% stronger than pre-cast or conventional cast-in-place concrete and typically has a compressive strength of 4000 to 8000 psi (28 to 55 MPa). The velocity of the application produces other major benefits along with higher compressive strength, reduced shrinkage means minimized cracking and therefore lower permeability. Upon the completion of shotcreting the tank and placement of the backfill, (which is the material from the original excavation) the concrete is in ideal conditions to cure to maximum strength. In other words a shotcreted tank is stronger, less porous and less prone to cracking. In addition, by using a spray applied process for placing the concrete, the end result is a monolithic concrete structure with no vulnerable section joints typical in other pre-cast or cast-in-place concrete processes.

Tanksmart tanks share these significant common advantages with a variety of traditional products:

• Rust-proof
• Long-lasting
• Interior constructed using NSF 61 approved materials
• No taste in potable water
• No smell
• Structurally strong
• Impermeable
• No corrosion maintenance required
• No heavy lifting equipment required during installation
• Wide variety of size options

Tanksmart tanks have the following uniquely inclusive advantages:

• Structurally pre-engineered and stamped
• Burial depth restrictions do not exist
• Traffic load limitations do not exist
• Special backfill is not required for structural integrity
• Anchoring systems are never needed
• Ballasting during installation is never required
• Site specific conditions can be accounted for in the design
• Tank design can be engineered to accommodate any site specific loading requirements
• Will not float out of wet excavations
• No exposed steel parts such as bolts, turnbuckles or cables to rust and corrode away
• Expedient onsite construction
• Monolithic structure leaves no exposed, vulnerable joints
• High sulphate resistant shotcrete
• Thicker tank wall than standard pre-cast tanks
• The most structurally robust design in the industry
• Constructed to engineered specifications
  
• The rigid liner eliminates liner adhesion issues
• Fittings and pipe connections installed onsite as needed
• Pipe connections at the tank are firmly encased in concrete
• Can be installed in limited space applications where large, fully manufactured one-piece tanks would not have access
• Can be constructed open-ended to any required length for sub-surface drainage, culverts or tunnels