I have commissioned the site investigation work, the findings of the geotechnical engineers have shown that the site has land fill debris to a depth of 6 metres, with subsequent contamination of the soil. This design report will be for the proposed light industrial/commercial buildings. The buildings will be framed with cladding, of various sizes. Some will be left as a shell with basic services others will be fitted out with offices on mezzanine floors.
RemediationAs the site was previously used as a landfill site, engineers have shown that the site has land fill debris to a depth of 6 metres, with subsequent contamination of the soil. These contaminants may include chemicals such as acids, alkalis, paint works and so on, petrochemicals may also be contaminating the soil with things such as hydrocarbons and asbestos from things like fuel storage. Metals are very likely to have contaminated the soil with metals like Fe, Cu, Zn and even asbestos from iron or steel works from things like old car parts. This makes the Rutherford Way land a brownfield site.There are 3 main categories of contaminated land remediation these are removal of contaminated material, site engineering and In Situ Treatment. The removal or remediation of these contaminants is costly as professionals are needed to dispose or contain the contaminants correctly. The methods of removal of contaminate can be the traditional approach which will be through digging up and disposing the soil, this method is affective but moves the problem from one place to another also because of this transportation costs will be high. The next method of treatment is site engineering solution this will be containing the contaminants by using impermeable barriers such as membranes and capping to create a barrier between the contaminated soil and clean soil.
This can be costly to get professionals to contain the soil correctly and safely. Another form of treatment is In-situ immobilisation of a material by washing, transforming or separating the soil they all change the nature of the contaminate to make it safe. Examples of this method are bioremediation which enhances actions of microorganisms to ‘eat’ the contaminates. Soil washing when soils are washed with detergents to clean contaminates out. Vitrification, when the ground is electrocuted to reach high temperatures and make solid. All these methods are costly as the price for professionals, labour, plant and tools will need to be taken into consideration.
For the site at Rutherford Way previously used as a landfill site I recommend to use the method of bioremediation to minimise and control the current contamination of the soil on the site. This method of remediation works by using microbes and microorganisms to consume the contaminants and converting them into water and carbon dioxide. This is an environmental friendly approach to remediating the soil as it uses natural processes to get the end result of safe uncontaminated soil. However, conditions for this must be right with an adequate temperature, nutrients and oxygen. If some soil is untreated the soil can be excavated and placed over perforated piping this is when air is pumped through pipes to enhance the process. With the right microbes and microorganisms used they can get rid of petrochemical, oils, heavy metals and many more contaminants. According to: (Chudley and Greeno, 2006)Foundations – Substructure The standard type of foundation that is most commonly used to support a steel portal frame building is a pad foundation. These are constructed with concrete and reinforced with steel rebar, they are usually in a cube shape with a simple design.
However, this type of foundation isn’t suitable with the soil at the Rutherford Way site as they are simple not deep enough and don’t allow for variations in the soil.Another type of foundation that could possibly be used for this development is a raft foundation, this type of substructure is very effective at spreading the load of the superstructure around the larger base of the foundations to reduce the load per unit area being imposed on the soil making it suitable to use with low bearing soils. This is constructed of a reinforced concrete raft which is simple in design and also simple in construction. However, this form of substructure tends to be wasteful in the amount of concrete used in its construction and isn’t used often for a portal frame building but for buildings with masonry load bearing block or brick walls which the new proposal won’t use but would be a suitable foundation to use if selected.As the site has contaminated soil up to 8m a form of piles would be the most suitable form of substructure to use to support the load of the superstructure and other loads. After remediation of the soil it is still possible for some of the soil to not be able to take the loads of the foundations this then limits the types of foundations you can use in your development.
Piles are foundations which can effectively transfer the loads of the steel portal frames and other loads through the weak (previously contaminated soil) down to much stronger and stable soils capable of supporting such loads without failure. A form of pile foundation is replacement piles also known as bored piles these are constructed by a hole being bored into the ground to the required depth, then the void made being with either reinforcement of insitu concrete. This type of pile does what it says in the name the pile will replace the soil it is in. replacement foundations are typically used in cohesive soils and when the site is located close to other buildings as displacement piles, may move the neighbouring foundations causing them problems. However, on the Rutherford Way site this is not necessary as no buildings are too close, making other methods of foundations more suitable.
For the substructure of the steel portal frame buildings I believe the best option would be displacement piles. This foundation type will use long columns driving into the ground to transmit the loads of the structure to a lower level of subsoil 8m deep that wouldn’t have previously been contaminated. This foundation works by being driven into the ground displacing subsoil through which it passes.
This is one of the more cost-efficient forms of piles as the process of construction is quite simple with basically a crane dropping a weight onto the pile column forcing it to go down into the soil, this process is repeated until the pile has been driven into desired depth or cannot go any further into the soil. The piles will then disrepute the loads into the ground. The actual column of the pile will usually be made from concrete with some form of steel reinforcement inside for added strength. The piles can then be joined above ground using concrete beam or pads placed above this then allows the structure to sit on top of the foundations. Frame – SuperstructureTheir a number of different frames you can use as the superstructure of a building a few of the most common are wooden frame, concrete frame and steel frame. Wooden FrameA wooden frame building is likely to be made out of timber as it’s a strong and cheap wood compared to other variety’s. This form of frame can be one such as cross laminated timber (CLT) where TLC panels just slot together around a timber frame, these panels are made in a controlled environment of site.
The structure of a timber frame can vary but will use beams normally timber and columns to support the structure, then connected together using glues and nails. However, this is unlikely to be used for an industrial building due to the materials property’s. Concrete FrameConcrete can also be used to create a frame, this will be made by pouring the concrete into formwork to mould the concrete and steel reinforcement in the concrete for added strength. The formwork may be pre-made of site and put together on site after concrete will be poured into the formwork and once dry the concrete will take the mould of the formwork.
The frame will also use columns and beams to support the structure. A concrete frame is more likely to be used for an industrial building due to its property’s and strength. Steel FrameThe last example I have given is a steel frame this is constructed by bolting the steel columns into the concrete pad, the columns can then be bolted to the steel rafters to create the roof.
One of the positives of a steel frame is that it can cover a large volume of space with minimal columns or support separating or obstructing the open space, this makes it an ideal construction method when creating industrial or commercial buildings. This is one of the most common frames for an industrial building and the type of frame I would recommend on using for your development. Some of the buildings will be fitted with offices, these will be located on mezzanine floors. The offices will be separated using stud interior walls followed with plaster board and then finished with paint. The offices will also have fully working electrics including sockets and lighting. They also may need radiators for heating only in the offices. The offices can be added to the building by creating a mezzanine floor within the structure, this is when the wasted space above is used by a 1st floor being added, it’s span won’t cover the whole surface area of the room.
This can be built similar to the superstructure using steel columns and bolted into the concrete floor, then horizontal beams to support the wooden flooring. A steel staircase will be added to reach the mezzanine 1st floor from the ground floor. As some of the buildings will be just the shell of the steel portal frame, this means the services will be capped off but accessible for the buyer/user if needed.
For the units with just a shell I recommend the steel frame to be a symmetrical pitched roof portal framed building. Some of the steel portal frame will need all services fitted in and offices located within building. For these types of units, I recommend a symmetrical pitched roof portal frame with an internal mezzanine floor. Both varieties of steel frame will have metal cladding on the exterior of the building, this will create the buildings envelope. The shell and the fitted portal frame will both need to provide a controlled environment that protects workers or occupants from the weather. The use of the building will determine the internal environment needed and what kind and specification of cladding will be needed. The walls and the roof will need cladding fitted around the building on all faces.
https://www.steelconstruction.info/Building_envelopes The walls of the frame can be cladded in an outer layer of steel sheet with weather proof paint, this layer will act as the weather proof layer making the building water tight. A cavity that contains insulation will act as the layer that helps insulate the building helping keep the warm air in and the cold air out. Then an internal leaf of steel liner sheet to make the cavity wall, this layer acts as the finishes with other finishes may also be added such as paint. Finally, metal fasteners will be added to hold the 3 main components of the cladding together and fixed in place to the bracing, columns, purlins etc.
The roof cladding will very similar to the wall cladding maybe even the same just different finishes in colour. http://www.cwct.co.uk/design/options.htmExample of CladdingPrimary services will be brought onto the site from the road wayElectricity, gas and mains drainage are available on the nearby main road.Drainage – Drainage pipes are usually laid under the road so your plans and designs must suit the existing drainage plan and be able to connect to it this is a factor you will need to consider when designing your buildings and layout. These drains will usually start from the building going into gully’s or allocated drainage areas, from there an underground drain pipe usually made from clay or plastic will transport the drainage water to the main drain pipes in the road, these main road pipes will then lead the water to a sewer or treatment site, where the water will be cleaned to use again.
Water supply – Clean water will start its journey from a reservoir where all the clean water will be stored once filtered and treated. The water will then be pumped from the reservoir to underground water main pipes usually in the roads, from the mains a service line pipe connects the water to the building, a water metre will be in that pipe to monitor water use and so the water companies know how much water you are using. Everything past the water metre is the building owners responsibility and the water metre and everything past that is the water companies responsibility. Electricity – Electricity will traditionally come from the national grid. It tends to start its journey at a nuclear power station, hydroelectric plant, solar farm, wind farm and a variety of other sources of energy. Once the energy has been created and transformed into electricity the electricity will run through wires to the step-up transformer, this transformer raises the pressure so it can travel long distances. The electric current then runs through power lines to a substation where the pressure is then lowered.
There will be a substation close to the site as the land sits on a commercial/light industrial area. The electricity then goes to either a pole transformer or a transformer box and the pressure is then lowered again. From here the electricity then goes to the building to a service box which measures how much electricity you use. According to: (Electricity-guide.org.
uk, 2018)Gas – gas will traditionally come from drilling deep into the earth where pumps will then extract the natural gas from the ground to the earths surface. The gas then travels through pipes underground called gas mains. Pipes leading of from the mains then transport the gas through pipes to a building where they will reach a metre that measures how much gas you use. Primary services distribution in the buildingsAs some of the buildings on the site will be just the shell of the building this means all services will be capped off with easy access to the building if required. However a number of the buildings will be fitted out with services and offices this then requires they must have all services in the building working to be used.Drainage – There will be a number of different drainage points in the buildings. The first being surface water drainage this will be collected from the roof using gutter systems which will lead to drains and drains in the pavements and roads which will collect the water. Fowl or waste water will come from things such as sinks and basins and waste water that does not contain excreta.
Soil water comes from urinals and toilets with water that does contain excreta. Both foul and soil will connect to a soil and vent pipe that works by letting gasses vent out of the top and the drainage water drain away down pipes to an inspection chamber that will connect the pipes together, the pipes will then lead to mains sewer work.Water supply – The fully fitted buildings will need both a cold water and hot water supply in the building, this will be used for things such as sinks using cold and hot water, also water to the toilet will be needed to be able to flush it. Ducts with plastic pipes inside will be placed into the hard-standing floor normally 750mm below ground to avoid freezing. These pipes will connect to the mains water supply that is already available from existing mains in the roads.
The ducts and pipes will then come to the surface where toilets and sinks will be, either sticking out of the ground and capped off for the shell buildings or more plumbing work connecting the utility’s such as sinks and toilets so they are fully functioning.Electricity – In the buildings with offices they will be fitted out with fully functioning electrics. These will include things like lighting in the main building and lighting in the offices on the mezzanine floor, electric sockets, fire alarm system, security systems, phone line and internet.
The lighting in the building will be run of electricity this means wires will be needed to connect the lights and switches, things such as cable trays will be used to tidy up the wiring. These cable trays may be connected to beams and columns inside the building with further sheet materials and finishes added to cover up the wiring completely. This technique of hiding and tidying up the wires may be used for most of the electrical wires inside the buildings.
In the offices this method isn’t likely to work as a separate environment is needed to work in, it is likely the wiring will be hide vertically behind the plaster board in the stud walls of the offices. A distribution board or an industrial fuse box will be used in the buildings as a circuit breaker and a main switch capable of turning off all electricity in the building.Gas – Gas will be capped off in both the shells and the fully fitted buildings with offices as gas isn’t usually required in industrial buildings. However, if the buildings do require a gas supply throughout the building the gas shall pass through copper pipes. Inside the offices the environment will be different to the open industrial working space, this means the offices will need to be heated. The heating in offices will come from radiators.