Plant Building Design – External

Plant Building Design – External

Plant design refers to the overall designing of a manufacturing enterprise/facility. The objectives of designing & constructing a sanitary food handling facility are to minimize harborages and to eliminate the entrance of pests and other sources of contamination.

Food Processing plants are quite different from the non-food processing ones, the main difference lies in areas of equipment, selection and sizing, working space design and these differences are due to storage life of foods is relatively limited and strongly affected by temperature, pH, water activity, maturity, prior history, and initial microbial contamination levels. Very high and verifiable levels of product safety and sterility have to be provided as foods are highly susceptible to microbial attack and insect and rodent infestation. Food processing generates wastes with high BOD loads which need special treatment before releasing it to environment.

Plant Designing: Premises and Surrounding

Objective for sanitary building are to minimize harborages and infestations of vermin (e.g., rodents, insects, birds, other pests), mold and mildew, and microorganisms and potential for contamination with environmental chemical pollutants.

It is imperative that an adequate pest control management program is in place for food processing and handling facilities. And proper records and documentation of a pest control program is important to the success of an overall sanitation program. Focus area’s being location of plant, site condition, preparation & maintenance, exterior lighting, driveways & receiving areas

  1. Location: Ideally, the food processing facility should be located away from sources of contamination e.g., chemical plant, sewage treatment facility, salvage yard, livestock housing, cow pasture, or body of water). In case source of contamination are found to be located near the plant, special precaution should be taken to avoid odors & contaminants from entering the yard or the facility.
  2. Site condition, preparation & maintenance: When preparing a new site for construction the site should be thoroughly cleaned of any potentially toxic materials and graded for appropriate drainage and prevention of standing or pooled water. Storm sewers should be designed and located to allow for adequate runoff and paving should be used to minimize dust. Trees and shrubbery should be no closer than 30 feet from the building, and grass coverings should end 30 inches from the building walls. To discourage rodents, gravel buffer should be established between the building and landscaping.
  3. Exterior Lighting: Exterior lighting attracts insects and hence location of these fixtures is of critical importance for preventing insects from entering the facility. The location of fixtures, especially when positioned over doorways, needs special attention. Lighting should be mounted on poles or standards, be at least 30 feet from buildings, and the light directed towards doorways and entrances. Lighting fixtures should be shielded with a non-breakable, transparent material.
  4. Driveways and receiving areas: Receiving area is the last line of defense in protecting the building, care should be taken to make sure that such areas are designed to minimize contamination and intrusion from pests. Asphalt driveways should be avoided, as this material may attract rodents. Driveways leading to receiving areas should be appropriately paved and constructed for adequate drainage. Drains should be designed with catch baskets for debris, and hose stations should be provided to facilitate cleaning and maintenance.

Plant Designing: Exterior Building

The primary objective of sanitary design in building construction should be to design and construct a building that is cleanable. Other objectives are to minimize contamination and adequately seal food processing and handling areas from sources of contamination. Simple and inexpensive preventative measures can be incorporated into building construction with regard to vermin proofing the building.

  1. Loading Docks, Platforms, and Receiving Rooms: Receiving areas and rooms should be enclosed as much as is practicable as an improperly designed and constructed receiving room will provide an attractive harborage for birds, rodents, and insects. Loading docks should be at least 3 feet above ground with the underside lined with a smooth, galvanized metal or similar material with a 12-inch over-hang to prevent rodents from climbing into the building. If overhangs should be constructed, then they should be sloped rather than flat, to be free of roosting and nesting areas for birds. Properly installed rapid open/close doors or air curtains should be used to discourage entrance of insects and birds.
  2. Exterior Walls: Building materials used for exterior walls vary in their need for preventative maintenance with regard to re-caulking of joints. For example, a poured concrete wall, needs less maintenance than other materials because it does not have seams. Low-density concrete block (e.g., cinder block), commonly used in domestic building, should be avoided unless an adequate sealer is used to avoid moisture intrusion and penetration of mold and mildew. Concrete block walls should be sealed at the base and capped at the top. Corrugated metal siding is the least desirable material for wall construction in a food handling facility. If used, it is imperative that it be adequately caulked along the base and at the seams.
  3. Roofs: The roof should be designed and built so it can be kept clean, especially where there is the possibility of product spillage or deposition on the roof. Food related dust (e.g. Flour, powdered milk, or grain) can accumulate on the roof and is an invitation to birds and insects. Smooth membrane type roofs are often the most desirable type of roof for food processing facilities. Tar and gravel roofs are usually not recommended as they tend to attract dust and are very difficult to clean and maintain.
  4. Openings into buildings: Any openings into buildings, including doors, windows, ventilation ducts, and other openings must be appropriately sealed and protected. Openings into the roof such as exhaust fans for air handling systems, ventilation ducts, and plumbing vent pipes must be sealed, and appropriately flashed and screened. Windows are discouraged in food processing operations as they present sanitation problems due to glass breakage and overall maintenance considerations. If used, windows should be designed to be flush with the inside wall and be permanently closed. Sills should be sloped away from the wall at not less than a 45-degree angle to prevent birds from nesting or dust from collecting.

Plant design specifies the equipment to be used, performance requirements for the equipment, interconnections and raw material flows in terms of flow charts and plant layouts, the placement of equipment, storage spaces, shop facilities, office spaces, delivery and shipping facilities, access ways, site plans and elevation drawings, required instrumentation and controls, and process monitoring and control interconnections, utility and waste treatment requirements, connections and facilities, the rationale for site selection, the basis for selecting and sizing critical pieces of equipment, ways in which the design was optimized and the engineering basis for such optimization.

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