UNDERGROUND TANK Mod. PANETTONE CORRUGATO

One-piece underground tank in linear high density polyethylene (LLDPE) fitted with hinged inspection cover. 

Containers used for the storage of drinking water, rainwater, and other food-grade liquids. The high strength and low reactivity of linear low-density polyethylene make these tanks suitable for containing various types of fluids (see the 'PE fluid compatibility chart' available on the website (www.rototec.it).

The tanks can withstand external temperature fluctuations from –20 °C to +80 °C, are not subject to deterioration over time, and the materials used ensure maximum reliability against corrosion and oxidation. If required for installation, holes can be drilled in the tanks at designated areas. The smooth surfaces of the tanks allow for easy maintenance, while their lightweight structure ensures easy transport and installation.

• Regolamento (CE) n. 1935/2004 del parlamento Europeo e del consiglio del 27 Ottobre 2004 about materials and articles intended to come into contact with food;
• Regolamento (UE) n. 10/2011 della commissione del 14 Gennaio 2011 about plastic materials and articles intended to come into contact with food;
• Regolamento (EU) 2020/1245 della Commissione del 02/09/2020;
• Decreto Ministeriale del 21 Marzo 1973 about the hygienic regulation of packaging, containers, utensils intended to come into contact with food substances or substances for personal use;
• Regolamento (CE) N.2023/2006 della Commissione del 22 Dicembre 2006 about good manufacturing practice for materials and articles intended to come into contact with food (GMP);
• D.P.R. N. 777 DEL 23/08/1982 and subsequent amendments and updates;
• The tank is suitable for containing food within the limits specified in the Attestato di Conformità n. C1070FPMFDC22_1 DEL 25/07/2022 emesso da CSI Spa – Milano.

Strictly follow the 'INSTALLATION INSTRUCTIONS' provided by ROTOTEC.

• The tanks can only be used underground. Do not use above-ground;
• When handling the tank, carefully follow the instructions supplied by ROTOTEC.
• Carefully check the integrity of the ROTOTEC tank;
• The tank must not be installed near to heat sources;
• The tank must be positioned on a flat stable surface;
• When installing the tank, to prevent the formation of algae, make sure that no light can filter in;
• Use flexible pipes when connecting to the water mains in order to prevent stresses during tank filling and emptying;
• Do not leave the tank without its cover for any length of time;
• In the case of rainwater storage, it is advisable to install a filter chamber upstream of the tank  to prevent a build-up of grit, silt, leaves, etc. inside the tank; for storing fluids not expressly indicated in this section, contact the technical office.

Warnings:

• When carrying out any of the operations, comply with Legislative Decree 81/2008 and subsequent amendments governing health and safety at temporary and mobile construction sites.
• On arrival of the goods, carefully check the material to make sure it corresponds to the order and the project data. Any defects and/or damage due to transport must be reported immediately. Contact the company directly by telephone, fax or e-mail.
• Check that the modular tank is provided with all the standard documentation (technical data sheets, installation instructions, etc.…). Inform the company of any missing documents. A copy will be sent immediately.
• Make sure that the gaskets, pipes and all the various parts other than in polyethylene are suitable for the liquid to be contained.
• Avoid impacts and contact with sharp-edged objects that could compromise the integrity of the product.
• Only handle the tanks when they are completely empty using the lifting eyes (where provided). NEVER lift the tanks by the inlet or outlet pipes.
• For the choice of backfill material and compaction methods, refer to European Standards UNI-ENV 1046 and UNI-EN 1610.
• During the installation works, mark the boundary of the working area with suitable warning signs.

Prohibitions:

• It is absolutely forbidden to install underground tanks above ground.
• It is strictly prohibited to use the tanks for storing industrial waste or liquids containing chemical substances or mixtures that are not compatible with polyethylene (see compatibility table supplied by Rototec).
• Underground tanks are NOT suitable and must NOT be used to store diesel fuel.

• On delivery, the goods must be unloaded from the truck using suitable means capable of lifting the weight. Please contact the Rototec offices for the weight of products.
• In the case of a closed truck unloading must take place from the side using a fork lift vehicle. The forks must be long enough to protrude at least 30 cm beyond the product. Take great care not to hit the product with the tip of the forks, to avoid damaging it (Fig.1).
• In the case of an open truck unloading may also take place from above using a crane or mechanical fork lift, using steel chains, cables or straps suitable for hooking to the lifting eye bolts present on the products or wrapping them around its external diameter (Fig.1-3)
• It is possible to use the same equipment described in the preceding points to move the material, always taking care not to hit the product or drag it along the ground, and never passing or standing under and in the vicinity of the loads being moved
• To prevent the load from becoming unbalanced, always place the chains, ropes or cables symmetrically, respecting the lifting angle which must NEVER be less than 45° (Fig. 3-4)
• All loading, unloading, lifting and movement operations must be carried out ALWAYS WITH THE PRODUCTS COMPLETELY EMPTY.
• During suspended movement the product can be kept still using one or more ropes, preventing it from turning around the connection point. In the same way it is possible to turn it, for example to lower it into the excavation or in general onto the installation point (Fig.2)

N.B. The best location for the tank is specified by the qualified technician according to his own thorough technical evaluation. These installation instructions provide the guidelines to follow during installation.

1.1 Excavate a hole of suitable dimensions with a flat bottom, leaving a space of at least 20/30 cm around the tank. In the presence of heavy soil (e.g. clayey subsoil) and/or groundwater, the distance must be at least 50 cm. Spread a 15/20 cm deep layer of 20 /30 mm washed gravel on the bottom of the excavation to allow the tank to rest on a uniform and level base. Excavated material must never be used as backfill.nThe excavation must be a minimum of 1 m from any structures.

2.1 Place the totally empty tank on a bed of 20/30 mm washed gravel spread at the bottom of the excavation, gradually fill the tank with water and at the same time backfill with 20/30 mm washed gravel. Continue with successive layers of 15/20 cm, filling the tank and then backfilling with gravel. Fill the tank to 3/4 of its capacity and backfill the last 40 cm with topsoil (NOT clayey/silty material, NOT excavated material). To prevent excessive pressure on the tank, NEVER use backfill material with sharp edges.

In the case of a tank with outlet pipe (e.g. aerobic trickle filters or gravity balancing tanks) seal the outlet pipe with a removable cover, then fill-backfill until half way up the tank, as indicated. After this, remove the plug and complete backfilling. Do not allow standing water to form in the excavation.

N.B. For installation in more severe conditions (groundwater, clayey soils or in sloping ground), refer to chapter 3 “Exceptional Installation”.

2.2  After the tank has been filled and the excavation suitably backfilled, gradually cover with topsoil ((NOT clayey/limey material, NOT excavated material) or with lightened material, e.g. expanded clay, to a depth of 30/40 cm, leaving the inspection covers exposed. In this way, the area concerned is suitable for pedestrian traffic, while the transit of motor vehicles within 2m of the excavation is prohibited.

When installing treatment plants, leave the tank filled with water. However, when installing a water storage tank, leave it full of water until the ground has fully settled (minimum 7 days. This period may vary based on the assessment of the designer). N.B. To render the site trafficable by motor vehicles, refer to Chapter 4 “Trafficability”.

2.3 EXTENSION INSTALLATION

If the tank is installed at a depth of 30/40 cm and the site is to remain open to pedestrian traffic, it is advisable to install the Rototec PE extension directly on the inspection holes. In the case where the tank is installed deeper than that previously indicated and therefore install more than one extension, which is an unfavourable condition and is not recommended, adhere scrupulously to the instructions reported in Chapter 4 “Trafficability”. The technician responsible for the installation will follow the instructions reported in the two paragraphs according to the installation depth.

2.4 VENT CONNECTION

a) When installing a pump, internally or externally, ALWAYS install an open-air vent, free and correctly sized, to prevent the formation of a vacuum and deformation of the tank when the pump is running. After connecting the vent, make the connections and check them.

b) In order to prevent the formation of bad smells and enable the treatment plant to function efficiently, ALWAYS connect a pipe (PVC, PP or PE) to the connection point provided for the biogas vent on the tank. Run the pipe to the highest point of the building or along the downpipes, but in any case higher than the level of the roof.

The pipe indicated on the drawing for the vent is not included in the supply.

2.5 MANHOLE INSTALLATION

The installation of manholes or covers of weight exceeding 50 kg must always be solid with the concrete slab, suitably designed for the load to support and exerting a uniformly distributed load. The slab, therefore, must NOT be constructed directly on the tank but must rest on undisturbed, load-bearing ground. DO NOT create brickwork elements that would compromise maintenance or eventual replacement of the tank.

3.1 INSTALLATION IN ZONES WITH GROUNDWATER

Installation in the presence of groundwater is not recommended as it represents one of the riskiest conditions for a storage tank. In this case, it is advisable to obtain a geotechnical report from a specialist. From the report, the installation technician will be able to define the expected pressure from the groundwater and design the backfill material and slab accordingly. In particular, he will design the backfill to have the necessary capacity for resisting the high lateral forces. The resistance capacity can be increased by inserting an electro-welded steel mesh. Construct the concrete slab at the bottom of the excavation, then spread a 10 cm thick layer of 20/30 mm washed gravel over the top to fill in the voids between the corrugations in the base of the tank. The tank filling and backfilling operations must always be carried out progressively. It is advisable, therefore, to half fill the tank and at the same time backfill with concrete and allow it to stand for 24/36 hours [points 1-2]. Then complete the tank filling and the backfill [points 3-4].

3.2 INSTALLATION IN ZONES WITH CLAYEY/LIMEY SOIL

Installation in areas with a mainly clayey/silty substrate and/or with limited drainage capacity is another unfavourable condition. A geotechnical report prepared by a specialist is advisable in this case also. From the report, the installation technician will be able to define the expected ground pressure (high in the case of clayey/silty soil) and design the backfill accordingly. In particular, the bottom of the excavation must be covered by a bed of 20/30 washed gravel and the sides of the tank backfilled with 20/30 m gravel to aid drainage. For tank filling and backfilling, see para. 2.1. A drainage system must also be provided at the bottom of the excavation.

3.3 INSTALLATION NEAR TO SLOPING GROUND

When the tank is to be installed near to a slope or on sloping ground, the tank must be protected by a reinforced concrete retaining wall, appropriately designed by a specialist, in order to balance the lateral thrust of the ground and to protect the area from possible infiltration. For tank filling and backfilling, see  para. 2.1.

4.1 LIGHT TRAFFIC - Class B125-EN124/95 - Max 12.5 tons

To render the site suitable for the transit of light vehicles, a self-supporting reinforced concrete slab, designed in relation to the load, must be constructed. The perimeter of the slab must be larger than the excavation to prevent the weight of the slab from bearing on the tank itself. It is also advisable to construct a concrete slab (for example 15/20 cm thick) at the bottom of the excavation, over which a 10 cm thick layer of 20/30 mm washed gravel must be spread to fill in the voids between the corrugations in the base of the tank. The self-supporting slab in reinforced concrete and the bottom concrete slab must always be designed by a qualified professional. The tank filling and backfilling operations must always be carried out progressively as specified in para. 2.1. The self-supporting slab is necessary to distribute the load of the covering topsoil, even when the tank is installed at a depth > 40 cm, as indicated in paragraph 2.3.

4.2 (A) HEAVY TRAFFIC - Class D400-EN124/95 - Max 40 tons

To render the site suitable for the transit of heavy vehicles, a reinforced concrete containment structure cast on-site with a suitable self-supporting concrete cover slab must be provided. The perimeter of the slab must be larger than the excavation in order to distribute the load on the containment walls and not on the tank itself. Then spread a 10 cm thick layer of 20/30 mm gravel at the bottom of the containment structure to fill in the voids between the corrugations in the base of the tank. The containment structure and cover slab must be designed by a qualified professional in relation to the expected loads. The tank filling and backfilling operations must always be carried out progressively as specified in para. 2.1

4.2 (B) HEAVY TRAFFIC - Class D400-EN124/95 - Max 40 tons

To render the site suitable for the transit of heavy vehicles, a self-supporting reinforced concrete slab ( ≥ 25 cm) must be constructed. The perimeter of the slab must be larger than the excavation to prevent the weight of the slab from bearing on the tank itself.

It is also advisable to construct a concrete slab (for example 15/20 cm thick) at the bottom of the excavation, over which a 10 cm thick layer of 20/30 mm washed gravel must be spread to fill in the voids between the corrugations in the base of the tank.

The filling and backfilling operations to 3/4 must always be carried out progressively as specified in para. 2.1. After the tank has been filled and the excavation backfilled, gradually cover the last quarter of the excavation with lean concrete and bars (Ø 10-12). Create the self-supporting slab over these, using a double layer of electro-welded mesh (Ø 8) with spacers.

ROTOTEC S.p.A. hereby guarantees its Water Division and Purification Division tanks for underground and abovegroud installation, made of linear high density polyethylene (LHDPE) using the rotational moulding technique, for a period of 2 years for manufacturing defects and a period of  25 years against full-depth corrosion.

This guarantee shall apply on condition that the articles are kept in a state of regular use, are subjected to periodic maintenance and are installed according to the methods indicated. The manufacturer will be in no way liable in the event of incorrect installation.

The guarantee will cease to be valid in the following cases:

1. If the underground installation methods are not strictly adhered to.
2. If the product is modified without the prior authorisation of the manufacturer.
3. In the case of non-compliant use.

The guarantee does not cover:

1. Installation costs.
2. Damage due to lack of use.
3. Damage to third parties.
4. Damage resulting from loss of the contents.
5. Transport costs.
6. Reinstatement of the site.

Rototec guarantees that all materials fully comply with the characteristics and conditions specified in the order confirmation and in the certificates/technical data sheet issued by the technical office.

Rototec will not be held liable for applications, installation, inspections or any operations undertaken at the buyer’s location or the final installation site.

Any products with defects resulting from carelessness, incompetence or negligence during use or due to incorrect installation or maintenance by unauthorised or unqualified personnel, or damage caused as a result of circumstances that cannot be traced back to manufacturing defects, are not covered by the guarantee.

Rototec will not be held liable for injury or damage either directly or indirectly deriving from incorrect installation, use or maintenance of the products sold.

Rototec products are supplied with technical data sheets, certification according to current standards and underground installation and maintenance instructions.