Building Services :Drainage, Rain Water Disposal and Harvesting


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Drainage- Sub- drains, Culverts, Ditches, Gutters, Drop inlets and Catch Basins,Rain Water Disposal for individual buildings, Rain Water Harvesting with examples and illustration for 4th ,P.T.U

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Building Services :Drainage, Rain Water Disposal and Harvesting

  2. 2. sr834 CONTENTS- · Drainage- Sub- drains, Culverts, Ditches, Gutters, Drop inlets and Catch Basins. · Rain Water Disposal for individual buildings. · Rain Water Harvesting 2
  3. 3. sr834 STORM DRAINAGE SYSTEMS A storm drain is defined as that portion of the storm drainage system that receives runoff from inlets and conveys the runoff to some point where it is then discharged into a channel, water body, or piped system. It consists of one or more pipes connecting one or more inlets. A storm drain may be a closed-conduit, open-conduit, or some combination of the two. The terminology "storm sewer" which has been in general use for many years, is gradually being replaced with the term "storm drain" to differentiate between sanitary sewers and storm drains. Storm drain will be used throughout this manual. 3
  4. 4. sr834 THE PURPOSE OF A STORM DRAIN IS TO COLLECT STORM WATER RUNOFF FROM THE ROADWAY AND CONVEY IT TO AN OUTFALL. STORM DRAIN DESIGN GENERALLY CONSISTS OF THREE MAJOR PARTS: system planning which includes that gathering and outfall location; pavement drainage which includes pavement geometries and inlet spacing; location and sizing of the mains and manholes. 4
  5. 5. sr834 REQUIREMENT FOR THE STORM WATER DRAINAGE Stormdrain systems should have adequate capacity so that they can accommodate runoff that enters the system for the design frequency.z Storm drain systems should be designed with future development in mind if it is appropriate. The storm drain system for a major vertical sag point that can't overflow elsewhere until the depth of water is two feet or greater, should have a greater level of flood protection to decrease the depth of ponding on the roadway and bridges. Where feasible, storm drains shall be designed to avoid existing utilities. The recommended minimum distance is 10 feet when the storm drain system is parallel to the waterline and 1foot when the storm drain system crosses a waterline. Attention shall be given to the storm drain outfall design to insure that the potential for erosion is minimized. Drainage system design should be coordinated with the proposed staging of large construction projects in order to maintain an outlet throughout the construction project period. The placement and hydraulic capacities of storm drainage structures and conveyances should be designed to take into considerationpotential damage to adjacent property and to minimizetraffic interruptionby flooding as is consistent withthe importance of the road, the design traffic service requirements, and available funds. Storm drain placement and capacity should be consistent with local storm water management plans. 5
  6. 6. sr834 SUBDRAIN A subdrain system is an underground network of piping used to remove water from areas that collect or retain surface water or groundwater. The network can be rather small, such as might be used to drain a limited area, or fairly large to drain a sizeable number of acres. Surface water can be collected into the subdrain system by installing a surface inlet or catch basin. Groundwater is collected by allowing water into the pipe through perforations. Both surface water and groundwater can be discharged to an appropriate outlet such as a nearby storm sewer, pond, or river. Both storm drains and subdrains are installed underground to carry water away from homes and businesses. Storm drain pipes are connected to the aboveground storm drain grates and primarily carry surface water runoff through the system. Subdrain pipes are not directly connected to the storm drain grates. instead, subdrain piping contains holes that allow the intake and passage of groundwater through the underground system. Subdrain piping has been installed in some areas of the City where high groundwater tables exist. 6
  7. 7. sr834 CULVERTS A culvert is a drainage pipe used to convey a stream through a road or embankment or may carry a stream for a long distance underground to a surface discharge location. Bottomless Culvert - Three Sided Double Reinforced Concrete Box Culvert (RCBC) Bottomless Culvert Arch Corrugated Metal Pipe (CMP) Its installation does not require a large quantity of pipe. 7
  8. 8. sr834 Corrugated Aluminum Pipe Arch (CAPA) Driveway Culvert High Density Polyethylene Pipe (HDPE) Reinforced Concrete Pipe Culverts are generally short in length and open at both ends and often must withstand substantial traffic loads 8
  9. 9. sr834 DITCHES Ditches are constructed to convey water from storm runoff to an adequate outlet. A good ditch is shaped and lined using the appropriate vegetative or structural material and does not cause flooding, erosion, or sedimentation. Energy dissipating structures to reduce velocity, dissipate turbulence, or to flatten flow grades in ditches are often necessary. 9
  10. 10. sr834 Importance to Maintenance & Water Quality Efficient disposal of runoff from the road will help preserve the road bed and banks. Well vegetated ditches slow, control, and filter runoff providing an opportunity for sediments to be removed from the runoff water before it enters surface waters. In addition, a stable ditch will not become an erosion problem itself. This will help alleviate roadway flooding, reduce erosion, and thus reduce maintenance problems. 10
  11. 11. sr834 Types of ditches 11
  12. 12. sr834 Rounded V-Shaped Ditch U-Shaped Ditch COMMON DITCHs SHAPE EXAMPLES 12
  13. 13. sr834 GUTTER • THAT PORTION OF THE ROADWAY SECTION ADJACENT TO THE CURB WHICH IS UTILIZED TO CONVEY STORMWATER RUNOFF. • A COMPOSITE GUTTER SECTION CONSISTS OF THE SECTION IMMEDIATELY ADJACENT TO THE CURB Rain gutter, a narrow trough or duct which collects rainwater from the roof of a building and diverts it away from the structure, typically into a drain. Street gutter, a depression which runs alongside a city street, usually at the curb and diverts rain and street- cleaning water away from the street and into a storm drain 13
  14. 14. sr834 Street gutter Rain gutter The gutter also helps to reduce erosion, prevents leaks in basements and crawlspaces, protects painted or stained surfaces by reducing exposure to water, and provides a means to collect rainwater for later use.  A curb and gutter forms a triangular Channel that can be an effective hydraulic conveyance facility which can convey runoff of a lesser magnitude than the design flow without interruption of the traffic.  Where curbs are used, composite gutter sections can be effective at increasing gutter capacity And reducing spread on the pavement 14
  15. 15. sr834 Drop inlets  A location where storm water runoff from an open area enters the storm drain system.  Drop inlets are usually part of the public drainage system, but can sometimes be considered private. 15
  16. 16. sr834 Types and uses of drop inlets Inlet 24”x24” Yard drain Inlet(multiple grate) In driveways &parking where water is intersepted over a large area 16
  17. 17. sr834 Catch Basins A catch basin is a structure in the form of a chamber which is provided along with the sewer line to admit clear rain Water free from silt, grit, debris, etc, into the combined sewer. Catch basins allow rainwater runoff to be safely collected to prevent road and property flooding. Catch basins are designed specifically for capturing and conveying stormwater. These are small masonry chamber (75 to 90 cm in DIA. And 75 to 90cm deep)which are constructed below the street inlet to prevent the flow of grit, sand, etc, in the sever lines. When stormwater enters these basins the grit, sand etc, settle down in the bed and the storm water free from all the enters the sewer. The outlet pipe of the catch basin is fixed 60 cm above the bottom (see pics). The outlet pipe is provided with a trap to prevent the escape of odours from the sewers to the catch basins. 17
  18. 18. sr834 18
  19. 19. sr834 Catch Basin Types & Uses Catch Basin Uses Catch Basin Type 1 With Catch Basin Type 1 (Special) Concrete Medians Curbed grass medians On Curb and Gutter where it does not protrude into the travel lane Catch Basin Type 1 (Special) Concrete Medians Curbed Grass Medians Catch Basin Type 9 In Ditches Outside of the Clear Zone In Low Areas Outside of the Clear Zone 19
  20. 20. sr834 In ditches, valleys or low areas where pedestrian traffic is unlikely Not to be used in the path of vehicular traffic Catch basin type 14 Median ditches on dual lane roadways w/earth median Side ditches on controlled access highway Low areas on controlled access highways where there should be no pedestrian traffic In paved medians with concrete median barrier May be a single basin or double basin Catch Basin Type 15 20
  21. 21. sr834 On curb and gutter Roadways On valley gutter sections with the face of catch basin at the back of paved lip On curb and gutter roadways On valley gutter sections with the face of catch basin at the back of paved lip Catch Basin Type 16 In low point on curb and gutter roadway In low point on valley gutter sections with face of catch basin at the back of paved lip Catch Basin Type 17 Catch Basin Type 18 21
  22. 22. sr834 Catch pits should be provided in the following sections- • When the sewers are laid at very small gradient, and the velocity of flow is less than self cleansing velocity. At such situations as the solids present in the sewage will not move and go on accumulating and will require continuous cleaning and maintenance of the sewer, which can be reduced by providing catch basins. • When the drains are passing along the water bound macadam road or in sandy area and the market(where lot of defuse is dropped in drains).Because in such areas if all the solids moving in the sewage are allowed to enter the sewage, they will choke the sewer line. The catch basin collects the solids from the storm water. These solids are to be removed at frequent intervals for the proper functioning of the catch basins, otherwise they will block the passage of storm water to the sewers, resulting in the flooding of streets . 22
  23. 23. sr834 Rain water disposal for individual buildings Heavy rainfall and long periods of rainfall can lead to problems with flooding. To reduce the likelihood of flooding the Building Regulations require all rainwater from new developments to be discharged by means other than mains drainage. This can include soakaways, storage tanks or into watercourses. The most common form of rainwater disposal is directly into the ground through soakaways, but storage tanks are becoming more popular as a form of rainwater harvesting. 23
  24. 24. sr834 Rain Water Harvesting Rainwater harvesting is the accumulation and deposition of rainwater for reuse before it reaches the aquifer. Rainwater harvesting is the process of intercepting storm-water runoff and putting it to beneficial use. Rainwater Harvesting is the collection of water that would otherwise have gone down the drain, into the ground or been lost through evaporation. Ground water resource gets naturally recharged through percolation. But due to indiscriminate development and rapid urbainzation, exposed surface for soil has been reduced drastically with resultant reduction in percolation of rainwater, thereby depleting ground water resource. Rainwater harvesting is the process of augmenting the natural filtration of rainwater in to the underground formation by some artificial methods. "Conscious collection and storage of rainwater to cater to demands of water, for drinking, domestic purpose & irrigation is termed as Rainwater Harvesting." 24
  25. 25. sr834 Why harvest rainwater ? • To arrest ground water decline and augment ground water table • To beneficiate water quality in aquifers • To conserve surface water runoff during monsoon • To reduce soil erosion • To inculcate a culture of water conservation This is perhaps one of the most frequently asked question, as to why one should harvest rainwater. There are many reasons but following are some of the important ones. 25
  26. 26. sr834 Advantages of rain water harvesting Rainwater harvesting provides an independent water supply during regional water restrictions and in developed countries is often used to supplement the main supply. It provides water when there is a drought, can help mitigate flooding of low-lying areas, and reduces demand on wells which may enable ground water levels to be sustained. It also helps in the availability of potable water as rainwater is substantially free of salinity and other salts. 26
  27. 27. sr834 By harvesting and using rainwater we can: Increase water availability for on-site vegetation Reduce on-site flooding and erosion Reduce water bills and groundwater pumping Extend the life of landscaping (rainwater is usually low in salt content and relatively high in nitrogen) 27
  28. 28. sr834 There are generally two methods of harvesting rainwater- 1.Passive Rainwater Collection Passive rainwater collection is the act of slowing down rainwater and letting it infiltrate on site rather than channeling it into the storm drain system. A passive system uses earthworks to control surface water flow and uses the soil as the storage container. Intercepted rainwater can be collected, slowed down and retained or routed through the site landscape using microbasins, swales and other water harvesting structures. Redirecting the roof downspout into a landscaped area is an example of pasive rainwater harvesting. 28
  29. 29. sr834 Active rainwater collection systems integrate a storage container, a tank or cistern, into the system to catch rainwater runoff for later use on the property. These tanks can be installed above or below ground. Above ground systems usually rely on gravity to disperse the water and serve smaller areas. The in ground system requires a pump but can provide water throughout the site. In either case active systems bring a great advantage -- water can be stored and used when the soils are dry (instead of while the ground is soaked from the same rain that filled your tank). Active systems are also more complex than passive systems, cost more and require more maintenance. ActiveRainwater Collection 29
  30. 30. sr834 The concentration of contaminants is reduced significantly by diverting the initial flow of run-off water to waste. Improved water quality can also be obtained by using a floating draw-off mechanism (rather than from the base of the tank) and by using a series of tanks, with draw from the last in series. The stored rainwater may need to be analyzed properly before use in a way appropriate to ensure its safe use The quality of collected rainwater is generally better than that of surface water. Contamination is always possible by airborne dust and mists, bird feces, and other debris, so some treatment may be necessary, depending on how the water will be used. Quality of harvested water 30
  31. 31. sr834 Rainwater harvesting systems can be installed with minimal skills. The system should be sized to meet the water demand throughout the dry season since it must be big enough to support daily water consumption. Specifically, the rainfall capturing area such as a building roof must be large enough to maintain adequate flow. The water storage tank size should be large enough to contain the captured water System setup 31
  32. 32. sr834 Rainwater harvesting can be harvested from the following surfaces Rooftops: If buildings with impervious roofs are already in place, the catchment area is effectively available free of charge and they provide a supply at the point of consumption. Paved and unpaved areas i.e., landscapes, open fields, parks, stormwater drains, roads and pavements and other open areas can be effectively used to harvest the runoff. The main advantage in using ground as collecting surface is that water can be collected from a larger area. This is particularly advantageous in areas of low rainfall. Waterbodies: The potential of lakes, tanks and ponds to store rainwater is immense. The harvested rainwater can not only be used to meet water requirements of the city, it also recharges groundwater aquifers. Stormwater drains: Most of the residential colonies have proper network of stormwater drains. If maintained neatly, these offer a simple and cost effective means for harvesting rainwater. From where to harvest rain 32
  33. 33. sr834 Rainwater harvesting diagram 33
  34. 34. sr834 A rainwater harvesting system comprises components of various stages - transporting rainwater through pipes or drains, filtration, and storage in tanks for reuse or recharge. The common components of a rainwater harvesting system involved in these stages are illustrated here. COMPONENTS OF A RAINWATER HARVESTING SYSTEM 1. Catchments: The catchment of a water harvesting system is the surface which directly receives the rainfall and provides water to the system. It can be a paved area like a terrace or courtyard of a building, or an unpaved area like a lawn or open ground. A roof made of reinforced cement concrete (RCC), galvanised iron or corrugated sheets can also be used for water harvesting. 34
  35. 35. sr834 2. Coarse mesh at the roof to prevent the passage of debris. 3. Gutters: Channels all around the edge of a sloping roof to collect and transport rainwater to the storage tank. 4. Conduits- Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area to the harvesting system. Conduits can be of any material like polyvinyl chloride (PVC) or galvanized iron (GI), materials that are commonly available 35
  36. 36. sr834 5. First-flushing A first flush device is a valve that ensures that runoff from the first spell of rain is flushed out and does not enter the system. This needs to be done since the first spell of rain carries a relatively larger amount of pollutants from the air and 36
  37. 37. sr834 (i) Charcoal water filter A simple charcoal filter can be made in a drum or an earthen pot. The filter is made of gravel, sand and charcoal, all of which are easily available. (ii) Sand filters Sand filters have commonly available sand as filter media. Sand filters are easy and inexpensive to construct. These filters can be employed for treatment of water to effectively remove turbidity (suspended particles like silt and clay), colour and microorganisms. In a simple sand filter that can be constructed domestically, the top layer comprises coarse sand followed by a 5-10 mm layer of gravel followed by another 5-25 cm layer of gravel and boulders. 6. Filter The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is a chamber filled with filtering media such as fibre, coarse sand and gravel layers to remove debris and dirt from water before it enters the storage tank or recharges structure. Charcoal can be added for additional filtration. 37
  38. 38. sr834 38
  39. 39. sr834 Broadly rainwater can be harvested for two purposes: Storing rainwater for ready use in containers above or below ground Charged into the soil for withdrawal later (groundwater recharging) 39
  40. 40. sr834 THANK YOU! 40