1.7 Road drainage system
The main purpose of a road drainage system is to remove the water from the road and its sur-roundings as fast as possible. The road drainage system contains two parts: dewatering and drain-age. Dewatering simply means the elimination of rainwater from the surface of the street (porous asphalt). Drainage on the other hand takes care of all the other infrastructural elements to make sure the road construction is dry. The pavement or wearing course is the top layer of a road. One of the functions of the pavement is to deliver a waterproof covering for the inner road structure. This can be reached if the pavement is resistant and has no cracks on its surface. The wearing course must also have a suitable cross fall to lead water (from rain, melting snow or ice) instantly away from the road surface on sides of the road. (DMRB VOL4)
Dewatering contains following elements:
– cross fall
– resistant road surface materials, waterproof top layer
A typical drainage system consists of following elements, French drain:
It is a pipe, buried in the ground, (pipe has holes in it that must face downwards, in order to filtrate water and also make sure no dust, collected with water will get into the pipe). Trench drain is dog-ged to minimum 1200mm(BS), and the pipe is placed on the bedding material, in the trench. Above piper, there is requirement to layer trench with special materials, like aggregate to help water per-colate.
The suggested cross fall is going to depend on the road nature and on the material used for the top layer. On a straight highway cross fall will settle between 3 and 5 %. On asphalt the recommended cross fall is 3 %, and for gravel roads it raises up to 5%. (BS 345-442)
Description of road drainage
Drainage system design is determinated in regulations included in DMRB, vol4, which I will take un-der account when specifying the road drainage. (dmrb, 2013)
After own research and analysis, I have decided that best drainage solution for access road to the side, would be parallel pipe od average size of 150 mm diameter. The pipe will be placed in the ground under several layers of sand and gravel. These layers will make role as a filter. The main purpose of the filter course in road drainage is to cut the capillary rise to the road structural courses above of it. Filter course material should be well graded with a maximum grain size of 31.5mm and should be non-frost-susceptible. (DMRB VOL4)
The brief above is my own AUTOCAD drawing of drainage system, followed information’s included on WLC Moodle. This image shows all the layers required for drainage filtration and it also contains accurate sizes of drain pipe and filtration layers.
2.1Sustainable Urban Drainage System
One of the tasks that have been set by my client is to consider a sustainable grey and rainwater system that can be used on the farm shop. Clever solution to that could be an installation of Sustainable Urban Drainage System (SUDS). In urban areas where many surfaces are sealed by buildings and paving, natural infiltration is limited. Instead, drainage networks consisting of pipes divert surface water to local waterways. In some cases, this has influence on the downstream flooding and decomposition in river water quality caused when sewers are overloaded by surface water leading to a release of dirty/not filtrated water into rivers. Sustainable drain-age systems aim to improve these problems by storing or re-using surface water at source, by decreasing flow rates to watercourses and by improving water quality. These technologies allow us to come up with many clever ideas for South Hill Farm regarding saving up and collecting water.
Advantages of SUDS
There is an increasing agreement in society that we need a more sustainable approach to handle surface water. Sustainable drainage systems imitate natural drainage processes to decrease the consequence on the quality and quantity of runoff water from developments and provide comfort, economic and biodiversity benefits. SUDS can also deliver additional benefits.
2.1.1Types of SUDS
Over recent decades, we have learned how urban drainage is developing and how can it adopt to new range of water management of urban water and surface water runoff. Newly built-up devel-opments need to be drained to eliminate surface water. Traditionally this has been accomplished by usage of gullies and underground pipe systems designed to carry the water away as quickly as possible. Nowadays new technologies allow us to for several different options of creating surface and underground water drainage system. As I have mentioned before, we have decided to collect rain water on South Hill Farm, however, I will allow myself to present different options available of the market.
Retention ponds are smart solutions for water level decrease and treatment. They are designed to support emergent and submerged water vegetation along their shoreline, which includes plants pleasant for view. Every runoff from rain is held and treated in the pool. The holding time pro-motes pollutant removal by sedimentation process and the opportunity for biological mechanisms to reduce nutrient concentrations.
These are shallow, broad and vegetated trenches, designed to store water flow. These can be used as transportation of runoff to the next stage of the water treatment and can be designed to promote infiltration where soil and groundwater conditions allow.
Permeable paving & roads
These are porous surfaced asphalt that allows water to infiltrate across entire surface. The water can be temporarily stored before infiltration to the ground, reused, or discharged to a watercourse or other drainage system. Surfaces with an aggregate sub-base can provide good water quality treatment.
Reed beds & Wetlands
A reed-bed, also known as a constructed wetland, is an engineered pool, which is similar to pond. They are constructed with gravels and sands which are usually planted with the common river reed. Water usually drains below the gravel level and suitable plants help water to remove pollu-tants from water.
Challenging climate changes, has led us to consider rain water collection. Relatively small tanks are placed in garden of individual and water can infiltrate through to the tank and then reused in sev-eral ways.
2.1.2Surface water arrangement for the site
Following the Water Environment and Water Services (WEWS) (Scotland) Act 2003, which make establishment of low and determinates hot to protect the water environment. Looking at latest requirements, call of environment defence and my own research, the best solution for sustainable site is to reuse rain water collected in a tank on the site. Water tank will be placed on the side of the farm shop, under the ground. Water that infiltrates through the ground and stored in the tank, can be reused for flushing toilets, washing hands, and other domestic tasks. Water will not be drinkable unless chemically cleaned and on such a scale as this would not be cost efficient or bene-ficial.
This commonly found table, shows average usage of water in households.
The brief included in Graded Unit, given by Julie, specifies that building should be sustaina-ble. There are several ways to keep this building sustainable. One of these could be water storage mentioned above. It can help to save money on water bills (if a water metre has been fitted). Could prevent flooding as you will be utilising and storing the water. It is easy to maintain and is environmentally friendly. Another way to keep construction sustainable is its orientation. South hill farm shop and coffee shop will be facing south east to gain solar power. Reason to that is because Sun rises on east and is on its highest position on south, then it sets on west. So, sunshine will cov-er south facing objects. Complex shape of the building will help it to maximise solar influence. The reason that this is so essential to a sustainable design is due to the use of thermal mass storing natural heat within materials such as brick or blockwork in the building.
The picture below, shows, how much sunshine can the building absorb.
Source of image:(http://tuznajdziesz.pl/produkty/artykuly/gdzie-montowac-kolektory-sloneczne-czy-lokalizacja-kolektorow-slonecznych-ma-wplyw-na-wydajnosc-inst-593/, 2013)
3 Materials used for framed building
Steel and wood products (timber, glulam) are the world’s most important engineering and construction materials. It is used in every aspect of our lives in construction environment. That is why, I have decided to use mainly these materials for constructing framed building on South Hill Farm. Below is short description about sustainability of these materials and their main properties.
Steel is very friendly to the environment. It is completely recyclable, when recycled, loses none of its essential properties. Has great durability and compared to other materials, requires rel-atively low amounts of energy to produce. Pioneering lightweight steel construction helps to save energy, resources and time when erecting. Steel industry has made enormous efforts to limit envi-ronmental pollution in the last decades. Producing one tonne of steel today requires just 40% of the energy it did in 1960. Dust emissions have been reduced by even more.
Wood (glulam) is a renewable building resource, but being renewable is not the same thing as being sustainable. Renewability is a single attribute, just like recyclability is a single attribute. Wood can no more be classified as a sustainable material based on a single attribute than can steel or any other building material.
Steel does not absorb water, so not only it solves issues with structural movement due to changes in moisture content or humidity, but eliminates or greatly reduces other dampness relat-ed issues such as rotting. When timber gets wet, it swells and when it dries, it shrinks, which can cause small cracks in the construction figure. If wood is considered for the primary framing materi-al, or even for components of the structure such as exposed wood beams or timber frame trusses, the shrinkage of the wood and the related cost of the special specifying required must be consid-ered. Following this option, we have to take under consideration that this wood will require regular conservation, which is costly, takes a lot of effort and the building may need to be closed during this maintenance, so shop will be losing money due to lack of customers.
The majority of glulam structures will perform their intended function for their service life with minimal maintenance. However, for this to occur, all the factors that influence the durability of the glulam need to be properly considered. Durability is one of the key performance factors used to assess the suitability of a timber species for a specific application. The durability rating of a species is based on the natural ability of the heartwood of that species to resist decay and insect pests. Wood is also elastic, which can benefit, when it is fixed.
Different types of steel are produced according to the mechanical and physical properties required for their application. Various grading systems are used to distinguish steels based on these properties, which include density, elasticity, melting point, thermal conductivity, strength, and hardness (among others). To make different steels, manufacturers vary the type and quantity of alloy metals, the production process, and the manner in which the steels are worked to produce particular products. The fact that steel can be manufactured, adjusted to customer needs, gives it many advantages, for example, avoiding spending extra costs, for specified chemical components or unnecessary amount in thickness, (for smaller constructions).
3.2Choice of materials for frame building
Considering materials mentioned above, the most suitable choice for this building will be steel framed structure because properly designed and constructed steel structures provide long-term durability. Building codes and industry standards require that steel structures be designed to toler-ate corrosion or to be protected against corrosion where corrosion may spoil strength or servicea-bility. Barrier coatings (such as paint) are available to coat and protect the steel surface isolating it from water and oxygen. Without water and oxygen, the steel cannot corrode. (from WLC moodle).
Picture commonly found from https://www.google.co.uk/search?biw=1280&bih=869&tbm=isch&sa=1&ei=XMTpWrqKA9D4kwWD-5P4Dw&q=steel+framed+building&oq=steel+framed+building&gs_l=psy-ab.3…0.0.0.55184.108.40.206.0.0.0.0.0..0.0….0…1c..64.psy-ab..0.0.0….0.wqYuURK1D7E#imgrc=id9mApQLQcA7FM: updated 2.05.2018.
For roofing of the building, will be used glulam beam, which self-weight is 19.4kg/m2, (from https://www.bc.com/manufacturing/boise-glulam/, web updated 2.05.2018). Glulam beam is glue laminated timber that can be manufactured and shaped to personalised requirements. Beams are manufactured in a variety of widths and depths with lengths up to 50 meters, which meets conditions of South Hill Farm construction. I will use Marley Thrutone slates that are rated A+ in the BRE Green Guide and they meet strength requirements to BS EN 492. Sizes of tiles are 600mmX300mm and weight is 200gramms per each, (information from the provider).
Picture commonly found from https://www.mbmfp.co.uk/products/engineered-timber-systems/custom-glulam-beams/, updated 2.05.2018.
Steel frames will be simply bolted to the wood framed roof. Also, the roof will stay exposed from the inside so clients can enjoy the view of natural materials like glulam beams.
Picture commonly found http://www.fforest.co.uk/products/glulambeams/default.htm, updated 2.05.2018.
For cladding I will use individual panels from tylormaxwel.com made of natural stone including quartzite, gneiss, limestone, sandstone or slate joined to a cement base that is reinforced with a light metal or fibre glass mesh at the base. Each piece is Z-shaped in order to hide the joints from view. It is very simple to install and doesn’t need specialised labour.
My own AUTOCAD drawing referring to WLC notes showing steel frame connection to the cladding.
Table showing weight of materials used for construction
South Hill Farm shop and café requires basement of approximately 500m^2. In order to de-sign and detail the basement with all particular qualities, I am going to take under account BS8102, Euro Codes and Construction Industry Research and Information Association (CIRIA). Basement can provide extra space for activities, valuable storage room, kitchen for the café or even stuff room.
The design of basements requires consideration of large number of factors and regulations re-quirements. Basement design involves the selection of combination of construction and environ-mental control system that, together provide the necessary control of the external environment to enable the required internal environment to be achieved.
image (euro code, 2011)
4.2 Ground water
After examination of ground condition, I can spot that ground water appears at level of 180cm and rises to 170 within 20 min. That allows me to contemplate several options of flood prevention of the excavated site. There are number of techniques by which ground water exclusion are ob-tained:
o Freezing ground water may cost a lot of money and time due to enormous number of holes required to be drilled around the excavation area. However, there are particular cir-cumstances in which freezing is the only reasonable method to regulate ground water. For example, when soil is too weak to allow drilling tunnel, like the one for railway station in Paris near Seine river.
o Forming resistant barriers by filling with cement, clay suspension. This technique is consid-ered in water bearing rock formation, where the use of high pump capacity or digging well does not calculate.
o Chemical consolidation for regulation of ground water in excavation is appropriate for sandy gravels and fine grading sands. Commonly used chemical material for chemical con-solidation is sodium silicate. When sodium silicate is mixed with other chemicals, strong and flexible silica gel can be formed.
o Ground water control by compressed air is often recommended in the case, when envi-ronmental concerns are met. Precisely when ground water is kept near reservoir for drink-able water. Therefore, usage of solid materials like cement is banned. Compressed air technique is commonly used for controlling ground water in excavations of shafts and tun-nels.
Source:(civil engineering technology moodle, 2017)
Best solution for dewatering ground in this case, will be sump pumping, where groundwater is allowed to enter the excavation where it is then collected in a sump and pumped away by robust solids handling pumps. Sump pumping can be effective in many circumstances. Is easy to fix in the excavation, economical and low technology required.
(ground-water engineering ldt, 2016)
4.3Types of basements
These are large arched basements of major public buildings such as castles date from Roman times. Later medieval church crypts had more complex intersecting cupolas with piers at relatively close centers.
Houses with a crawlspace have enough room underneath to crawl, but certainly not to stand up. This is so that you can get access to plumbing pipes or other utilities usually and also to provide a more stable foundation for the house than having no basement.
Full basements are the most common basement type they are high enough that you can stand up in them. They usually form good living spaces provided the ceiling height is high enough for com-fort.
Most city center commercial constructions and many industrial buildings include the facility such as basements. These basements may be of significant depth where they are used for underground parking facilities. In commercial developments or congested city areas, basements usually occupy the whole site area to maximize the use of valuable land space below ground. This type of base-ment could be used as a great solution for the farm shop. There is large space required for storage kitchen and other facilities.
Image (cira, 2013)
4.4Types of foundation
There are three main methods of construction of a basement:
• Continuous bored piles,
• Diaphragm walls,
• Secant piles.
Contiguous bored piles
Bored piles are fitted as close to each other as possible to form the continuous wall before the ex-cavation takes place. The accuracy of placing the piles depends upon the type of pile and the method of placing, but piles will imitate to the final shape of design structure or basement.
image (WLC moodle, 2016)
Secant piles are time of retaining wall. These are piles that cut into each other, forming continuous wall. Firs are drilled into the ground and filled with weak concrete female piles. Then in between them are drilled stronger, male piles, which are reinforced and made of stronger concrete.
(WLC moodle, 2016)
4.5Choice of construction technique (also see CAD drawing)
Taking under consideration many different ways of constructing the basement, also taking under an account type of soil on South Hill Farm, I have come to conclusion that the best solution for basement will be diaphragm wall. These walls are commonly used in clay and sand with gravel are-as. The resulting wall is substantially watertight. Guide walls are spaced to be the final wall thick-ness apart are first constructed by the main contractor. Between these walls a trench is excavated to the required depth by the specialist contractor. As excavation continuous, the sides are pre-vented from falling in by keeping the excavated area filled with bentonite slurry. This is a 3–6% mixture of a form of diatomaceous earth in water.
● installation is free from vibration and excessive noise
● walls are constructed with minimum disruption to adjacent areas
● these walls form a dual purpose: they avoid the need for any temporary sheeting to the excavation and they become the final structural wall of the permanent works. (Some form of in-ternal facing is usually needed for cosmetic purposes)
● diaphragm walls are substantially watertight
• The excavation is carried out using a heavy self-guided mechanical grab suspended from a large crawler crane.
• As the excavation proceeds, support fluid was added into the excavation to maintain the stability of the surrounding ground and to prevent a collapse. This takes space on a site as fluid has to be stored, when not in use.
image (bacsol, 2016)
BS 8102: 2009 Code of practice for guard of structures against water from the ground, brings us categories of basement waterproofing required. Since basement has to be durable and last for years, it has to be also water resistance. I will provide the construc-tion with several solutions regarding protection materials from water.
There are three different main types of water protection:
This type of construction relies completely on a continuous fence of a waterproofing membrane, which can be on the external faces of walls and floors, sandwiched within the construction, (between layers) or on the inner faces of walls (picture below). Membranes are not usually fixed to floor surfaces and left uncovered as they lack the essential wearing qualities. If applied to tops of slabs, a protective slab will have to be combined over the membrane, to hold it in place. In this type of construction, the building itself is not specifi-cally designed to be watertight and effectively it may be designed to the requirements of BS EN 1992-1-1.
(euro codes, 2011)
image (euro codes, 2011)
Type B construction normally takes the form of a reinforced waterproof concrete box without need of applied membranes. The box is designed to BS EN 1992-3 so that crack control minimises the risk of water penetration. Limits on crack widths depend on the wa-ter table and/or intended grade of use. Where the water table and risk is classified
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