Author: John Dowling is a senior project engineer with international project delivery specialists, PM Group’s food sector and a member of Engineers Ireland. John has more than 13 years’ experience working across the food and dairy sector

Irish milk output is expected to increase 50 per cent by 2020 due to the lifting of the milk quota system earlier this year. This milk is manufactured into value added consumer products and ingredients such as cheese, yogurt and infant formula. As the last major investment in the Irish dairy industry was in the 1970s there is now a requirement to build large multi-product milk processing plants. This article will address the key consideration required by clients, engineers and project management companies embarking on the development of a multi-product milk processing facility. It will cover the essential areas including design fundamentals, expandability and future-proofing, master-planning, layout design principles including process, utility, amenities and support functions.

Definition of facility requirements

As with all projects the definition of facility requirements (also often called the Statement of Requirements or SOR) is a key activity at the start of the project. When designing a large facility it is important to identify clearly with the client what the project drivers and priorities are. Typical project drivers and priorities are safety, capital cost, good manufacturing practice (GMP) and hygienic design, project schedule, quality etc. Capital cost can be the basis on which decisions are made on whether a project will proceed or not. GMP and hygienic design are very important for a dairy facility as product recalls are expensive and more importantly can severely damage a brand or reputation. The quality of the build and the plant’s longevity are major factors as clients want their plants to be around for at least 30 to 40 years. Leadership in Energy and Environmental Design (LEED) certifications are not that common yet in the food industry in Ireland but are worth considering during the early phases of a project. Define at the start which products are to be manufactured e.g. powder, cheese, butter and what the output capacity of the plant will be. This is key to determining the size of major equipment like dryers, evaporators, cheese vats which in turn impact on the building size and layout. On completion of the SOR the concept stage of the project where typical layouts can be developed can begin.

Site layout considerations

There are a number of options when it comes to layout. The layout philosophy should be based on the requirements of the facility. There are three main options that can be applied to different dairy processes but the one selected depends on the size and shape of the overall site. A linear flow plant is the ideal as this has raw material/raw milk in at one end and feeds directly into processing, then packaging and then goods out and the process is in a continuous line. The administration block, labs and utility building can be separate from the production plant. This type of layout allows space for future expansion on a phased basis. Another option is an 'L' shaped flow, which is similar to linear but may need to fit into a narrower site. This style of layout has the same functionality to expand. The administration block, labs and utility building can again be separate from the production plant and all have the ability to expand in the future. If the size of the site is a constraint then a 'U' shaped flow may work better. This layout option is not ideal in terms of future expansion, but does suit a site with a small footprint.

Safety considerations in plant layout

During the early design and concept stage safety should always be a key driver. Personnel access, platform design, escape routes, machine access, operability and process safety are an example of some of the main considerations. Carrying out regular Design Risk Assessments (DRAss) ensure that all aspects of safety are considered during the design phase. In the Republic of Ireland the statutory role of Project Supervisor Design Process (PSDP) is key to ensuring that safety is considered, risks are mitigated against (possibly engineered out) and safety is designed in. As the process design progresses a Hazard and Operability study (HAZOP) is required in order to evaluate and identify any problems that represent risk to personnel or equipment, or prevent efficient operation. HAZOPs are carried out by a suitable trained person(s).

Layout principles and sustainable master-planning

Once the products have been defined and it’s clear what will be produced, space planning and designing of the facility around its process can start. The layout should have suitable expandability and it should be future-proofed to allow for installation of future lines needed for product changes or new products to react to market conditions. Having fallow space on the site allows for this but comes at a cost. At this stage consideration needs to be given to whether the building is single storey or multi-storey. By going multi-storey the overall footprint can be reduced but equipment also dictates this. Spray dryers have to be installed in multi-storey buildings, where wet processing or cheese production can be in single storey buildings. Something that is often an oversight is the construction grid. The grid is very important for the detailed design of the building as you want to avoid columns as much as possible within the building. Typical grids would be 12m x 12m, 12m x 24m or 6m x 6m. Master-planning is a very worthwhile exercise at this stage. It can be difficult to take a long-term view of how the site will develop over the next five to 10 years and is akin to crystal ball gazing. But the exercise does focus the mind of senior management and helps them to plan for the future e.g. five-year plan for the building. Expandability and masterplanning are linked somewhat and the final master plan is a road map for the site for the future.

Site selection considerations and permitting

To avoid ending up with a site that doesn’t work now or for the future, a site selection exercise should be completed. Consideration should be given to the site aspect/slope and its suitability for the proposed layout. Are the ground conditions suitable for the extensive facility to be built on it? When considering a dairy facility the transportation infrastructure needs to be well developed to be able to facilitate the amount of traffic associated with a large processing facility. Utility supply (water, electricity, gas) is extremely important and dairy plants are high users. The availability of a gas supply opens up the opportunity for a Combined Heat and Power (CHP) plant. The level of waste water treatment required on the site and whether there is a municipal treatment plant available are also important considerations. Permission shouldn’t be overlooked during the design phase as it can lead to schedule and ultimately design problems. Things to consider are planning, building codes, fire codes, environmental impacts, effluent discharge licence and environmental impact statements. It is good to have early liaison with government agencies to understand local requirements.

Layout design development

When developing the layout design it’s important to consider it from the process point of view. Warehousing and logistics considerations also have a major effect on a building’s footprint. Once these two key areas are finalised, it is possible to develop layouts for the utilities, services and ancillary functions. The size and type of process equipment dictates the building size and this is particularly the case where spray dryers can require a 30 to 40 meter dryer tower. The recommended approach is an 'inside out design' whereby the building is designed around the process. Process flow considerations are critical as there may be restrictions around powder conveying distances and pumping distances which dictate how building blocks are set up. Good manufacturing practice is now standard across the dairy industry and ensures safe quality foods for the consumer. In designing the layout the location of high, medium and low care areas need to be optimised. This can be achieved by keeping high care areas together where possible, otherwise there can be issues for operators having to continually gown up and gown down. It’s accepted that there is separation between wet and dry areas and the design should allow for lean movement of people and goods within the facility. When considering warehousing and logistics a good starting point is to work out storage requirements for raw ingredients, packaging material and finished goods. The key term here is Days on Hand (DOH). This will affect the size of a raw material warehouse, number of tanker bays, number of silos and size of finished goods warehouse. In a dairy there will be in-process storage requirements so chill stores (4ºC), freezers (-18ºC) and tempering rooms need consideration. It is now possible to develop the layout for the utilities, services and ancillary functions. The utilities design will depend on the site selected and whether there is mains water or water from a well on site, availability of natural gas etc. Typical ancillary functions are facilities (canteen, toilets, lockers, offices and laboratories), roads, truck and car parking, site security, weighbridges etc.

BIM/3D

With the widespread adoption of Building Information Modelling (BIM) in the design and construction industry by clients, consultants, vendors and contractors it is even more feasible to achieve effective and efficient project delivery. For the design of a complex process like a dairy plant, BIM can be a very useful design tool and allows for the plant to be fully designed in 3D before it goes to the installation stage. BIM can be utilised to model all structures, equipment, piping, HVAC and electrical containment integrating the process and packaging elements. This has significant design benefits including clash detection and is a very powerful co-ordination tool used to complete design reviews as well as facilitating client approvals and for early continuous constructability reviews. One significant drawback can be integration issues where different vendors are using different software

Constructability in design

It is important to consider the constructability during the design phase. By preparing a construction execution plan you can get buy-in from all stakeholders (process vendors, contractors, project team etc.). You need to consider site set-up and location of compounds and where you have a brownfield site you also need to consider construction versus operations separation. A preliminary construction schedule can be developed and monitored during all stages of design.

John Dowling was part of the PM Group team that carried out the project management, design and the construction management of Glanbia’s Belview facility. Belview is the largest single capital investment (€180 million) in Ireland by an indigenous Irish company and can process up to three million litres of milk per day into a range of specialised milk powders and nutritional ingredients. PM Group was awarded the European Construction Institute (ECI) 2015 Large Scale Project of the Year Award for the Belview project. A recent lecture by John Dowling for the Engineers Ireland Agricultural and Food Division and Project Management Division, is available to view below: