Brine and Tanks in Gemlik Olive Processing Plants

Olive processing plant safety in Gemlik: process and calendar

Safety in an olive processing plant cannot be planned without knowing how the process works. In Gemlik this process is written down: Gemlik Olive is a designation of origin registered in the name of the Gemlik Commodity Exchange, and its geographical boundary covers the districts of Gemlik, İznik, Orhangazi and Mudanya. The TÜRKPATENT registration certificate (No. 76) describes the production method in detail and contains information that matters for OHS:

• Harvest: Starts at the end of October or early November and ends at the end of December; the olives are picked by hand.
• Brine method: After washing, the olives are put into concrete pools or polyethylene, polyester or fibreglass tanks. The brine concentration is adjusted to 8–12% with a Baumé hydrometer. To keep the olives in the brine, the tanks are covered with boards and pressure is applied. Fermentation takes about 6–9 months, or about 5 months with aerated fermentation. Salinity is checked every 2–3 days.
• Dry-salting method: The olives are layered in drums, one layer of olives and one of salt; salt equal to 10–14% of the olives' weight is used. The drums are turned upside down and shaken every 2–3 days; this stage lasts at least 3–4 months. For oiled dry-salted olives, maize or sunflower oil is used in the packaging.
• Packaging: Tins, plastic, doypacks, glass or vacuum packs.

Gemlik Olive is fermented naturally without alkaline treatment. The inspection calendar in the registration certificate places the processing stage in the November–April period; in other words, the busiest time for plants is the winter months. Because there is no OIZ (organised industrial zone) in Gemlik, plants are spread across the district centre and olive-growing villages; we describe our service model in the area on our Gemlik OSGB page.

The olive brine tank: working on top and at the edge

The olive brine tank is a piece of equipment visited every 2–3 days throughout the processing season. Salinity measurement, checking the pressure and topping up the brine are often done from the top or the edge of the tank. This creates three risks:

• Falls from height: Climbing onto tall tanks with portable ladders and balancing at the edge. Annex 1 of the Regulation on Workplace Buildings and Annexes requires suitable guardrails on the open edges of platforms and working landings and in places with a risk of falling from height. For rows of tanks that are climbed often, a fixed walkway platform with guardrails is always safer than a portable ladder.
• Falling into a tank or pool: Open tank mouths and concrete pools at floor level carry a risk of drowning for anyone who falls in. Cover unused openings, mark pool edges and prevent entry by people who are not on duty.
• Lifting heavy pressure weights: Board covers and pressure weights are lifted at the tank edge, reaching and bending. Split the weights into smaller pieces, use a lifting aid if possible and set a two-person working rule.

Moving the measuring point outside the tank, for example by taking the sample from a valve at the bottom of the tank, is a simple engineering solution that reduces the number of times people climb on tanks. For the general rules on work at height, see our article what is work at height.

Gas and confined space risk in the fermentation tank

In natural fermentation, yeasts and bacteria produce carbon dioxide. Carbon dioxide is colourless, odourless and heavier than air; it can build up at the bottom of tanks, inside half-empty tanks, in below-ground pools and at low points of poorly ventilated halls with many tanks. The gas that builds up displaces oxygen. A person entering an oxygen-depleted atmosphere may lose consciousness without noticing any warning sign.

The jobs with the highest fermentation tank gas risk:

• Entering a tank or pool emptied at the end of the season to clean it
• Reaching or climbing into a tank to retrieve a tool or cover that has fallen in
• Valve or pump work in below-ground pools and pits

Each of these jobs should be planned as confined space work: a written entry permit, gas measurement from outside and at different heights before entry (oxygen first), forced ventilation, an attendant waiting outside and a rescue plan ready. For the order of measurement and choice of instrument see our article on confined space gas measurement, and for the permit system our article on working in confined spaces. A filter mask does not supply oxygen; nobody enters a tank where oxygen deficiency is possible wearing a filter mask. We explain this distinction in our article on gas mask filters.

In enclosed halls with many tanks, consider installing fixed carbon dioxide or oxygen detectors and a general ventilation system, depending on the risk assessment. The regulation requires maintenance and repair of mechanical ventilation systems to be carried out by authorised persons once a year (Annex 1 item 17).

Slips in the olive plant and the effect of salt

Brine overflows, leaks, washing water, olives dropped on the floor and the oil used in preparing oiled dry-salted olives keep the risk of slipping high all year round in an olive plant. The regulation requires workplace floors to be sound, as level as possible and non-slip, and channels collecting waste water to be covered (Annex 1 items 26, 57). These measures work on site:

• Sloped floors where water does not collect, and drainage channels with grates
• Non-slip floor coverings in wet areas
• Spilled brine and olives cleaned up immediately; the person responsible and the frequency written down
• Safety shoes or boots with non-slip soles; for choosing the class see safety shoe classes
• Speed limits for forklifts and pallet trucks in wet areas

Salt has another effect: corrosion. Salt water wears out guardrails, stair treads, cover hinges and electrical installations. Sockets, panels and light fittings in wet, salty environments should be selected with a protection rating suited to the environment, and main and sub-distribution panels should have residual current devices (Annex 1 item 8). For details see our article on earthing and residual current devices. The general framework of slip prevention is in our article on preventing slips, trips and falls.

Salt, dry-salting drums and manual handling

In brine preparation, salt sacks are carried by hand; in the dry-salting method, turning and shaking the drums every 2–3 days is repetitive, heavy manual handling that goes on for months. Measures:

• Keep drum size and full weight at a level that can be turned by hand, or use a device or tipping mechanism for turning.
• Bring salt sacks to the station on pallets; raise the pallet to waist height to reduce lifting from the floor.
• Share the turning work among employees; avoid the same person doing this job for the whole shift.
• Salt water irritates the eyes and skin; cracks and sores can form on hands in prolonged contact with brine. Use suitable gloves and eye protection, and provide eye washing facilities where there is a risk of brine splashes.

For lifting technique and load limits see our article on manual handling and lifting technique, and for task sharing and rotation our article on repetitive movements and assembly line ergonomics.

The olive packaging line

Olive packaging involves taking the processed olives from the brine pool or dry-salting containers, grading them, filling them into jars, tins, doypacks or vacuum packs and palletising them. The main risks and measures:

• Conveyors and grading machines: Entrapment in rotating rollers and drums. Moving parts should be covered with guards, and the machine stopped and isolated from its energy source to clear jammed olives or to clean; see LOTO lockout and tagout.
• Filling and sealing machines: Hands caught at lid and tin sealing stations. An interlock that stops the machine when the guard is opened, and an accessible emergency stop button.
• Glass and tins: Cuts from broken glass and sharp tin edges. Cut-resistant gloves and a written broken glass procedure.
• Noise: Especially on tin lines. We plan measurements with authorised laboratories and enter the result in the risk assessment.
• Stacking: Forklift-pedestrian separation in the palletising and loading area.

For the general guarding principles of food machinery, see our article on safety in food machinery.

Season planning: what to do before the harvest

The plant's busiest period is also when seasonal workers start. Before the harvest begins:

1. Check platforms on top of tanks, guardrails, ladders and tank covers; repair salt corrosion.
2. Prepare the confined space entry permit form, the calibration of the gas detector and the rescue equipment.
3. Complete the periodic inspection of forklifts and pallet trucks; the maximum period for this equipment is one year.
4. Have the electrical installation and panels inspected.
5. Complete seasonal workers' pre-employment examinations and induction training before their first working day. If some workers do not speak Turkish, plan the training using the methods in our article on language and OHS training for foreign employees.
6. Update the emergency plan to include the tank area and a confined space rescue scenario.

Verify your plant's hazard class from the NACE code for your activity; for the method, see our article on how to find your hazard class.

In our OHS specialist and risk assessment services, we observe the brine and dry-salting processes step by step and tie the measures for the tank area, confined spaces and the packaging line to the season calendar. Other risks in the food sector are on our food page.

Frequently Asked Questions

What should be done before entering a brine tank?

The tank should be emptied and ventilated as far as possible, a written entry permit issued, and gas measurements taken from outside at different heights, starting with oxygen. While someone is working inside, an attendant should be outside and rescue equipment should be ready.

What gas forms during olive fermentation?

In natural fermentation, yeasts and bacteria produce carbon dioxide. Carbon dioxide is heavier than air and builds up at the bottom of tanks and at low points, displacing oxygen. This is why a tank that looks empty can also be dangerous.

How are slips prevented in an olive plant?

Sloped floors and drainage with grates, non-slip floor coverings, immediate cleaning of spilled brine and olives, and shoes with non-slip soles should all be applied together. Forklift speed should also be limited in wet areas.

What training should seasonal workers receive?

Each seasonal worker is given at least 2 hours of face-to-face, hands-on induction training before starting work; basic training is then completed within 3 months of starting at the latest. Rules for working on top of tanks and in confined spaces should be part of the induction training.