Domestic Services Part 2 2019-2020 PDF

www.civil.eng.usm.my  At the end of this topic, student should be able CO1. Able to apply knowledge in construction to: technology in the construction of building and infrastructure. CO1 – PO1 1. Explain the aim and p...

www.civil.eng.usm.my  At the end of this topic, student should be able CO1. Able to apply knowledge in construction to: technology in the construction of building and infrastructure. CO1 – PO1 1. Explain the aim and principles of external (Engineering knowledge) drainage system; CO2. Able to suggest appropriate construction 2. Explain each type of surface drainage materials and techniques to suit various system; construction requirements. CO2 – PO1 (Engineering knowledge) 3. Explain each type of subsurface drainage system; CO3. Able to evaluate construction problems and provide technically viable solution. 4. Suggest a suitable solution for drainage CO3 – PO2 (Problem analysis) problems.  External (or exterior) drainage is a removal of excess water to a suitable outfall. must be removed from all areas such that water will Source of excess water: not be retained in surface surface runoff, depressions. subsurface & foul water Maintain the hygienic and adequate Excess water is carried in the drains disposal of foul water and to avoid to sewers, and from sewers to a flooding and other damage. suitable outfall or treatment plant. Benefit: erosion control, Fig. 1. External Excess water removal of surface water, drainage is detrimental to the turf and maintain soil’s and other plant life and structural capability and need to be removed improving trafficability. Basic exterior sewers: subsurface, surface, slope drainage, & downspout & gutter system  o water from a rainfall that does not infiltrate the soil; o excess rain or irrigation water will naturally flow to areas of lower elevation. o the excess water may remain ponded, causing poor 1. Surface Water aesthetic conditions as well as destroying turf or damaging buildings, homes and hardscapes. o surface water is considered to be clean and can be discharged direct into an approved water course or soakaway. water contaminated by domestic 3 o waste = effluent; o require treatment to render it main forms of clean before it can be discharged excess water in into an approved water course. building drainage 2. Surface water terms: o results from surface infiltration; o need to be collected from the earth to lower the water table level in the subsoil; 3. Foul or Soil Water o considered to be clean and requires no treatment and can be discharged direct into the approved water course or soakaway.  o the controlled removal of surface runoff a) Channel drain resulting from precipitation and irrigation. o it begins with shaping and smoothing the b) Catch basins and inlets land into a watershed that directs runoff to o Install gutters and downspouts on 1. Surface drainage systems ditches, catch basins, storm sewers or other homes to direct rainwater down and drainage systems. away from the home, to reduce the o without proper surface drainage, subsurface chances of saturating the soil around drainage efforts are considerably more the foundation. difficult. 4. Downspout and gutter systems 2. Subsurface drainage systems Roof drainage (gutter & 4 a) Deep open drains rainwater pipe) basic types b) Pipe drain residential c) French drain drainage systems o the removal of gravitational water o a slope drain is a pipe or lined channel from the soil. which extends from the top to the o source of subsurface water is bottom of a cut or fill slope. percolation (water moving vertically o designed to convey concentrated and laterally underground) that is runoff to protect exposed slopes from generally attributable to precipitation upstream runoff. 3. Slope drainage systems or irrigation. Slope drainage  Comprehensive Drainage System  Engineers and architects divide drainage into surface and subsurface drainages.  A complete drainage system incorporates both surface and subsurface drains.  Surface drains to remove heavy volumes of rainfall that fall in short spans of time and subsurface drains to remove water which percolates into the soil.  Soil has a natural ability to absorb just so much water.  At the point the soil becomes 100% saturated with water, it cannot absorb anymore.  With no place to go, additional rainfall accumulates on the surface resulting in flooding and erosion.  This is another reason it is critical to incorporate surface drains into any drainage plan.  A. Drain Pipe Systems 1. 2. Sewer & B. French Drain Corrugated Drain Pipe Pipe C. Half Round Drain 1. Perforated Drainage components D. Rain Gutter 2. Solid E. Channel Drain F. Catch basins & inlets Fig. 2. List of drainage components commonly G. Prefabricated drain installed in residential system areas  coils along the outer and/ A. Drain Pipe Systems or inner wall 1. Corrugated pipe Two types of drain pipe 1. Perforated systems for residential 2. Solid drainage applications smooth wall 2. Sewer & Drain (S&D) (smooth wall) pipe Perforated pipe is used for subsurface drainage, and solid pipe is used to convey water from surface and/or subsurface drainage systems.  1. Corrugated pipe Characteristics: i. Manufactured from high density polyethylene vi. Corrugated pipe is available in solid or (HDPE). perforated. ii. Available from 10 ft. lengths to coils up to vii. The perforated version is sometimes known as 1,000 ft. long. slotted drain tubing. iii. The longer the coil the fewer couplings viii. Perforated pipes are used for subsurface necessary and the less labor required. drainage applications. iv. Corrugated pipe is flexible & it can follow the ix. Coextruded dual wall corrugated pipe is a contours of the ground, change directions in variation to single wall corrugated pipe. the trench, and adapt to underground x. It is more rigid and has a smooth interior wall obstacles more easily than rigid pipe. which gives it the characteristics of Sewer & v. Labor savings and flexibility are two important Drain pipe. advantages of corrugated pipe.  1. Corrugated pipe Disadvantages of corrugated pipe: 1. Plumber’s snakes cannot be used to clean out the pipe as they get caught in the pipe’s corrugations. 2. Corrugated pipe and fittings snap together and, henceforth, are not watertight. 3. If slope is critical, the flexibility of corrugated pipe makes it difficult to obtain constant slope unless the trench bed is sloped properly. 4. Corrugated pipe has more friction loss than smooth wall sewer and drain pipe, hence reducing flow and increasing sediment deposits in the drain pipe. Corrugated pipe and Corrugated pipe with Coextruded dual wall Plumber’s snakes fittings perforation corrugated pipe 2. Smooth Wall Sewer & Drain Pipe (S&D) S&D pipe is much more rigid than corrugated pipe and manufactured from PVC, ABS and Polyethylene. Easy to maintain a continuous slope in critical areas. Will compensate for peaks and valleys in the trench bed. PVC and ABS connections can be solvent welded or glued together ensuring watertight connections. Drain snakes can be used on S&D pipe if the pipe line becomes clogged. 2. Smooth Wall Sewer & Drain Pipe (S&D) However, S&D pipe is more labor intensive and less flexible than corrugated pipe. S&D pipe is available as ASTM 2729, ASTM F810 or SDR 35. SDR 35 has a thicker wall and stronger crush strength than ASTM 2729 or smooth wall polyethylene pipe. SDR 35 pipe is more expensive than ASTM 2729 or polyethylene pipe. Another type of S&D pipes are: DWV (Drain Waste & Vent) - used in indoor sewer application.; and PVC schedule 40 - used in pressure application such as lawn sprinkler systems.  B. French Drain ▪ French drains (Fig. 3) are a type of subsurface drain, utilize a buried perforated pipe installed in a gravel bed with a filter sock or geotextile fabric envelope lining the trench. ▪ Water from the surrounding soil enters the gravel bed, flows into the drain pipe and utilizes gravity to flow towards the discharge point. ▪ Perforations in single wall corrugated pipe are slits surrounding all sides of the pipe. ▪ Perforations in smooth wall drain pipe (S&D) and coextruded dual wall corrugated pipe are small diameter holes located in rows on one side of the pipe which should always face downward to Fig. 3 French Drain prevent soil from infiltrating the pipe.  B. French Drain ▪ French drains are the most common method for evacuating excess ground water which has infiltrated into the soil. ▪ However, French drains require labor, large trenches, rock or stone, filter fabric and therefore are more expensive than surface drainage systems. ▪ Migrating soil fines will accumulate on the filter fabric or in the drain pipe, potentially inhibiting water flow and eventually clogging, limiting the life of the drain system (Fig. 4). Fig. 4 French Drain pipe  C. Half Round Drain ▪ Half Round Drain - Common type of drain ▪ Perfect for both domestic and light commercial used in Malaysia’s residential for rainwater applications, drainage. ▪ The half round rainwater system comes in 75 mm, 112 mm and 150 mm diameter if more capacity is required. ▪ Available in grey, black, brown and white to suit most environments; ▪ Light weight makes high work safer; ▪ Quick and easy to cut and join; ▪ No painting and minimal maintenance required. Fig. 5. Half Round Drain  D. Rain Gutter ▪ A rain gutter or surface water collection channel is a component of water discharge system for a building’s roof (Fig. 6). ▪ Gutters prevent water ingress into the fabric of the building by channeling the rainwater away from the exterior of the walls and their foundations. ▪ Many materials have been used to make guttering: cast iron, asbestos cement, UPVC (PVCu), cast and extruded aluminium, wood, copper, and bamboo. Fig. 6. Rain gutter  E. Channel Drain ▪ A.k.a. as trench drain, linear drain, line drain, slot drain, or strip drain. ▪ It is linear surface drains connected together to a length appropriate for the specific installation (Fig. 7). ▪ Runoff water collected in the drain is discharged to bottom or end outlets, or catch basins all of which are connected to drain pipe. o available in ▪ Act as perimeter drain at the edge of the slope. different materials: concrete, steel, ▪ Ideal applications for channel drains are hardscapes plastic. or large flat work areas of concrete, asphalt, brick, o grates are available pavers, etc. in cast iron, steel, brass and plastic ▪ [hardscape generate more runoff than landscapes due to lack of water absorption]. Fig. 7. Channel Drain  F. Catch basins and inlets ▪ Catch basins and inlets used in conjunction with a drain pipe system – to remove large amounts of surface water from an affected area. ▪ Typically used in low areas of turf landscapes, hardscapes, driveways, parking lots, etc. ▪ Catch basins and inlets are traditionally available in sizes from 3” round to 48” square and different materials including concrete, brick, and plastic basins, cast iron, steel, brass and plastic grates. ▪ A catch basin should be used in areas where debris Fig. 8. Catch basin like mulch, leaves, sand, silt or grass clippings are & inlet prevalent  G. Prefabricated drain system ▪ Prefabricated drain systems are typically rectangular with a narrow profile and available in 4” through 60” depths. ▪ They are a type of subsurface drain and used in both natural and synthetic turf applications to collect and convey water away from the problem areas. ▪ Compared to French drains, their narrow cross-section allows them to be installed in more narrow trenches without significantly disrupting natural turf areas (Fig. 9). Fig. 9. Prefabricated drain system  G. Prefabricated drain system ▪ A prefabricated drain system usually consists of a cuspated plastic core which is completely wrapped in a geotextile fabric. GEOTEXTILE FABRIC ▪ The fabric may be glued to the core or sewn. ▪ The geotextile prevents intrusion of fine soils into the drainage core. ▪ Water passes through the fabric and flows through the core to the discharge point. ▪ The geotextile filters the fine-grained soil particles leading to the development of a stable filter cake. Fig. 10. The component in prefabricated drain  Others types of drains Swales: ▪ Natural surface drain swales are the least expensive method of Swales removing undesired surface water run off. The fabric may be glued to the core or sewn. Terraces : ▪ The primary purpose of terracing is to move surface runoff water from sloping areas. Bench terraces and tile outlet terraces are the two types of terraces that have been used in turf drainage. Terraces Water passes through the fabric and flows through the core to the discharge point. Culverts: ▪ Culverts can be installed under flat work, gravel or dirt to allow water to pass under an obstruction. Culverts  A. Good Design Practice B. Basic Components Surface Drainage System C. Roof Drainage System D. Channel Drain E. Catch Basins & Inlets Fig. 11. The Outline  A. Good Surface Drainage Design Practice ▪ A drainage system has 3 major phases: ▪ This capacity can be calculated using the collection (catchment), conduction, and dispose following formula: (discharge) of drainage water. Annual rainfall (in mm) x Roof surface area (in m2) ▪ The design process is simply a continuation of: = Roof catchment capacity. 1. what size the catchment (collection) system needs to be, ▪ Conducting system (gutters) - channels all 2. what size and type the conducting system around the edge of a sloping roof to collect and needs to be, transport rainwater to the downspout. 3. what format the disposal/discharge system should take. ▪ Disposal/discharge system – 2 widely used components for disposal are Flo-Well and Pop- ▪ Catchment system – collection of rainwater. Up emitter. ▪ Roughly speaking, 1 mm of rain over a m2 of roof ▪ Rainwater or surface water should not be = 1 L of water. discharged to a septic tank/ waste water treatment system.  A. Good Surface Drainage Design Practice ▪ A surface water drainage system should: 1. carry the flow of rainwater from the roof to an outfall, 2. minimize the risk of blockage or leakage, 3. be accessible for clearing blockages, 4. be adequately protected from accidental damage from sources such as traffic, ground settlement and tree roots, 5. be adequately protected from accidental Fig. 12. Components for pollution by means of a discharge from foul disposal: Flo-Well and Pop-Up drains, oil spillage or other pollution emitter sources.  B. Basic Components ▪ Poor drainage causes obvious problems: standing GUTTER water, foul odor, diseased or dying plants, mud, ruined turf, and basement water. ▪ Surface drainage system should transfer the runoff water (rainwater) from roofs, paved areas and other surfaces of a premise to a suitable outlet or disposal facilities. ▪ The system involves: gutter, downpipes (down spout), drains, pipes, swales, storage and treatment facilities (if necessary). ▪ Typical surface drainage components for residential in Fig. 13: Fig. 13. Typical surface drainage components  C. Roof Drainage System (gutter & downspout) ▪ A roof drainage system is a system that is ▪ The water will then flow through the gutter and installed on the roof to divert water and debris then make its way to the downspout where it off the roof. will then absorb into the ground. ▪ The components for a roof drainage system are ▪ A gutter not only help collect water from the a gutter system and downspouts (Fig. 14). roof, but it will also protect the landscaping from soil erosion and home’s foundation from ▪ A gutter system is a component of a roof cracking. drainage system, which allows water, twigs, leaves, and other debris to collect off of the gutter roof and flow toward the downspout and onto the ground. ▪ The water from the roof drips into the gutter system, which is a long piece of material that is installed along the edge of the roofline. downspout Fig. 14. Gutter and downspout  C. Roof drainage system eaves gutter (gutter & downspout) ▪ 3 types of gutters (Fig. 15): eaves gutter, box gutter and valley gutter. ▪ Eaves gutters are located on the outside of a building. ▪ Box gutters and valley gutters are located box gutter within the plan area of the building and the intersecting sloping surfaces of a roof, respectively. ▪ The traditional material for domestic gutters and rainwater pipes is cast iron but uPVC systems are very often specified today because valley gutter of their simple installation and low maintenance costs. Fig. 15. Types of gutters A closed eave has very Open eaves is an little or no overhang overhanging eaves where (extension beyond the the rafters and siding). underside of the roof are visible from below. Fig. 16. Eaves Gutter Types  C. Roof drainage (gutter & rainwater pipe) installation ▪ Installing a roof drainage system is depending ▪ The flow into a gutter depends on the area of on types of roof (either flat or pitched roof) surface being drained and whether the surface and the size of the roof. is flat or pitched. (Tab. 16) ▪ For a flat roof, the drain will be installed onto the actual roof and then the drain will be linked together. ▪ For pitched roofs, the water will just flow into the gutter system. Fig. 17. Typical eaves details  C. Roof drainage (gutter & rainwater pipe) installation ▪ Table 17 shows the largest effective areas ▪ The Table shows the smallest size of outlet which should be drained into the gutter sizes which should be used with the gutter. which are most often used. ▪ These sizes are for a gutter which is laid level, half round in section with a sharp edged outlet at only one end and where the distance from a stop end to the outlet is not more than 50 times the water depth. ▪ At greater distances, the capacity of the gutter should be reduced. ▪ Gutters should be laid with any fall towards the nearest outlet. ▪ BS 6367: 1983 Code of practice for drainage of roofs and paved areas. C. Roof drainage (gutter & rainwater pipe) installation Rainwater pipes should discharge into a drain or gully but may discharge to another gutter or onto another surface if it is drained. gully trap Fig. 18. Rainwater pipe connection to gully C. Roof drainage (gutter & rainwater pipe) installation Rainwater pipe which discharges into a combined system: sewers that carry foul wastewater and surface water in the same pipe, should do so through an intercepting trap. intercepting traps Fig. 19. Rainwater pipe discharged into a combined system  C. Roof drainage (gutter & rainwater pipe) installation ▪ The size of a rainwater pipe should be at least ▪ Different metals should be separated by the size of the outlet from the gutter. nonmetallic material to prevent electrolytic ▪ A down pipe which serves more than one gutter corrosion. should have an area at least as large as the combined areas of the outlets. ▪ The materials for gutters, rainwater pipes and joints used should be of adequate strength and durability. ▪ All gutter joints should remain watertight under working conditions. ▪ Pipes inside a building should be capable of withstanding the airtightness test. ▪ Gutters and rainwater pipes should be firmly supported without restricting thermal movement, and Video 1. How to install gutters & downspout  D. Channel drain installation ▪ Channel drains are a variation of surface drains, Standard installation ideal in hardscapes such as patios, walkways, swimming pools, parking lots and driveways. ▪ The hardscape surface is slightly sloped in one direction or plane to the perimeter channel drain with the same principle as a gutter on the roof of a building. Fig. 20. Channel Drain Video 2. Channel Drain Installation  D. Channel drain installation Standard installation 1. Excavate a wide and deep trench to 5. Design bottom or end outlets into the channel accommodate the channel and bedding concrete run in the appropriate location and glue to the or sand. drain pipe or fittings. 2. Erect a string line at each end of the drain run 6. PVC cement end caps where appropriate. as a guide for laying the channels to the required level. 7. Using either wood, plastic or steel stakes, 1/2” or 5/8” rebar, anchor channel to the trench 3. Begin channel installation at the discharge end bed every 24” on each side of channel. of the run where the outlet(s) are located. 8. Backfill with either concrete, sand, or soil 4. Install channel end-to-end PVC cementing depending on the application. sections together. 9. Pour slab to grade and finish concrete.  Channel drain installation ▪ Figure 21 illustrates a non-vehicular traffic ▪ Figure 22 illustrates a concrete base installation in which a concrete base is not underneath the channel recommended for light required. Compact soil and a 1” sand base. traffic and heavy load applications. Fig. 21. Channel drain for non-vehicular traffic Fig. 22. Channel drain for heavy load application  Catch basins and inlets installation ▪ Catch basin – A structure with a grate on top used 3. An inlet is often installed directly on top of the to collect and divert surface runoff to an drain line (Fig. 23). Use catch basins in underground drain pipe system. At the base of the applications where it is necessary to collect catch basin is a sump or sediment trap to collect debris from runoff water in a sump area. This debris. helps minimize clogging of drainage pipes. ▪ Inlet – A grate on top of a pipe riser that allows water runoff to enter directly into a drain pipe and does not contain a sump. Installation 1. Choose an inlet or basin size according to the amount of rainfall, surface area and soil type. It may be necessary to install more than one inlet or basin to accommodate excessive runoff or a combination of low spots. 2. Locate low spot or any area where excess water will accumulate. Fig. 23. Catch basin & inlet  Catch basins and inlets installation 4. Dig a hole deep enough for overall height of 10. Ideally, the catch basin outlet should be basin and grate. equipped with an elbow facing down to prevent debris from washing into the outlet drain line 5. Install basin in hole on top of a firm base. (Figure 7-3). 6. Work from the discharge point back to the grate. 11. For hardscape installations, the grate should be installed and taped over prior to pouring 7. Excavate the base of the trench with a minimum concrete or backfill to prevent debris from 1% to 2% slope to ensure drain pipe slopes to the entering drain. discharge point. 12. The tape is removed immediately after 8. Connect pipe to the basin. Backfill trench and area around basin. installation. In landscape installations, straw bales or fabric can be used to protect the 9. Ideally, the catch basin incoming drain line grate during construction. should be at an elevation equal to or higher than the outlet drain line.  Catch basins and inlets installation Installation (cont’d) 13. Grates should be recessed below grade a 17. Basins should be installed on top of compacted minimum of 1/8” for non-traffic installations gravel, sand or concrete. and 1/4” for traffic installations. 18. To avoid standing water in the basin, drill 14. Basin or inlets may be encased in concrete for holes in the basin bottom. This will allow heavier load applications. excess water to leach out. A gravel base is recommended for this application. 15. In asphalt or hot mastic applications the basin should be encased in concrete for strength 19. Finish grade should slope a minimum 1% to 2% and to prevent distortion. to the grate. 16. PVC primer and medium body fast set PVC solvent cement should be used to cement all components. Tape should be used to connect corrugated pipe to components. Catch basins and inlets installation Video 3. Catch basin & inlet Installation  A. Drain Types B. French Drain Subsurface Drainage System C. Prefabricated Drain system Fig. 24. The Outlined D. Flo-Well and Pop-Up Emitter  A. Drain Types ▪ Subsoil drainage systems are provided to drain away subsurface water in order to: 1. increase the stability of the ground and 4. increase soil strength by reducing the footings of buildings by inducing a more moisture content. stable moisture regime and reducing ▪ Classification of subsoil drain systems: foundation movements due to the variations in the soil moisture content; 1. French drain; 2. mitigate surface water ponding and 2. Prefabricated drain; waterlogging of soils by lowering water tables; 3. Flo-Well & pop-up emitter. 3. alleviate ground water pressures likely to cause dampness in below-ground internal parts of buildings or damage to foundations of buildings, other structures, or pavements; and/or  A. Drain Types The types of subsoil drains commonly used: Fig. 25. Types of Subsurface Drain  A. Drain Types ▪ Subsoil drains may be installed on flat ground, in a sag or depression, or on sloping ground. (a) Basic system: a trench with fill or filter material (commonly sand or gravel). A.k.a. rubble drain. (b) Geotextile filter: (c) Pipe drain: the addition of a the addition of a pipe to promote more geotextile lining to rapid drainage. A.k.a. French drain. This prevent external fine is the most common type of subsoil drain. soil particles being The pipe is perforated to allow easy washed into the filter entry of water and can be rigid or material and clogging flexible. it.  A. Drain Types (d) Pipe Drain with Capping to Exclude Surface (e) Geotextile Around Pipe: Water: two further variations – an impervious cap for The pipe is wrapped in geotextile to situations where the drain is intended to prevent piping and loss of filter collect only subsurface flows, and bedding material. material for cases where the base of the excavation is unsuitable as a pipe support.  A. Drain Types filter material (soil) geotextile (f) Geocomposite (g) Geocomposite Drain in Narrow Drain in Shallow (h) Soil Filter Layer to Avoid Trench Trench Clogging of Geotextile: Geocomposite drains of various an external layer of filter material configurations and manufacture can be provided around the geotextile provided. These are usually of plastic encompassing the filter material. wrapped in geotextile and various This might be used where there is proprietary systems are available. a likelihood of fine particles or deposits, e.g. iron precipitates, clogging the geotextile.  B. French Drain Installation ▪ The most reliable way to eliminate undesirable, ▪ Slotted pipes are better than pipes with small free-standing water is to install French drains round holes because they tend to reduce the with slotted pipes, filter fabric and gravel. amount of fine soil particles that get into the pipe. ▪ The old way of installing French drains is to do it without the gravel and the fabric. ▪ Without the gravel and the fabric, however, the drain can clog up with sand and soil over time. ▪ The best practice for installing French drains is to use perforated drainage pipes, which allow water to enter or exit through small openings along the pipe. ▪ The perforations (openings) can be circles or slots. Fig. 26. French Drain Installation  B. French Drain Installation 1. Dig a trench along the outside of your footing. 2. Lay the pipe on the virgin soil. It is very The trench should be at least 2 feet wide, and important that the pipe always be sloped from a can be as deep as 6 feet for a basement or as higher starting point to an ending point of lower shallow as 2 feet for a slab-on-grade home. elevation, so gravity can force the water out. 3. The grade should always slope away from the home to ensure that the water is directed away from the walls of the home. 4. Cover the pipe with at least 12 inches of washed gravel. 5. Lay filter fabric over the gravel to prevent any soil from clogging the pipe. 6. Back-fill the foundation with top soil back to its Fig. 27. The Trench original grade height.  B. French Drain Installation Video 4. French Drain using Video 5. French Drain using Corrugated Pipe Perforated S&D Pipe  C. Prefabricated Drain Installation o Prefabricated Drain Systems (Fig. 28), are an alternative to French drains. o Sometimes called vertical or strip drains. o Ideal for heavy use areas such as athletic fields and golf courses. o Limited usage in residential area. o For subsurface drainage, the drain should not be covered with soil. Instead, cover it with sand to the surface. Fig. 28. Prefabricated o Proper installation will prevent unhealthy turf Drain directly above the subsurface drain lines.  C. Prefabricated Drain Installation 1. The sod is cut and removed from the trench. 5. Excavated soil should not be used as backfill unless it has minimal silt or fines. The use of 2. Drainage trenches should be deep enough to excavated soil for backfill prevents drainage of allow appropriate soil cover over the drain to the surface and sod. See backfill specifications establish healthy turf and a minimum 2” space below. below aerifier lines. The drain should be at a depth to collect the ground water desired. 6. The temporary wood stakes are removed. 3. The drain is placed in the trench and may be 7. The sand is flooded with water, not tamped, to centered using temporary wood stakes. On promote proper compaction. hillsides, the drain is placed on the uphill side of the trench. 8. For surface water installations, the trench is topped off with sand to bring the backfill up to 4. The trench is backfilled with select sand the top of the trench, allowing for sod. backfill. If soil from the trench is a porous Subsurface installations can be topped off with granular media, the trench may be backfilled soil and sod. with soil excavated from the trench. 9. The sod is then placed back over the trench.  D. Flo-Well and Pop-Up Emitter o Consists of 2 units: (1) Flo-Well unit; and (2) Pop-up emitter. o Both are used as discharged points. o Flo-Well is a dry well, collect, retain, and direct storm water on-site. o Pop-up Emitters acts as the discharge point of a drainage system, allow water captured through drainage system to be released in water-safe locations like curbside drains. o The pop-up emitter is opened by the hydrostatic pressure of water flowing through the drain pipe and as flow diminishes the emitter closes. Fig. 29. Flo Well Installation  D. Flo-Well and Pop-Up Emitter o Pop-up Emitters have a flat profile and are spring-loaded to automatically close during dry weather, preventing damage from lawnmowers and keeping pests out of the drainage system. Fig. 30. Pop-up Emitter D. Flo-Well and Pop-Up Emitter Video 6. Flo-Well and Pop-Up Emitter Installation ▪ Soakaways are used to manage surface water at its source, and serve as an alternative option to draining off (dispose) surface water via a stream or sewer system. ▪ A soakaway is a hole dug into the ground, filled with rubble and coarse stone which allows Fig. 31. A 3D Illustration of surface water to percolate back into the earth Soakaway close to where it falls. ▪ As part of a full drainage system it is an efficient and low environmental-impact way of dealing with surface water (also called runoff, rain water or storm water). ▪ There will be a pipe leading into the soakaway, from the area where there is excess water, like a gutter from a roof, a driveway drain or a French drain. Fig. 32. A Soakaway Installation ▪ Soakaways are probably the most common form ▪ A soakaway must always be the first choice but of surface water disposal and are usually must not be used: suitable for areas less than 100m². 1. Within 5m of a building or road, 2.5m of a ▪ Soakaways are generally formed from square or boundary or in an area of unstable land in circular pits, filled with rubble or lined with dry ground where the water table reaches the jointed masonry or perforated concrete ring bottom of the soakaway at any time of the units. year. ▪ For soakaways serving areas greater than 25m² 2. Near any drainage field, drainage mound or reference should be made to BS EN 752-4, or other soakaway so that the overall soakage BRE Digest 365 Soakaway design. BRE Digest capacity of the ground is exceeded and the 365 is the most commonly used document. effectiveness of any drainage field impaired; ▪ Percolation tests should be carried out to determine the capacity of the soil. 3. Where the presence of any contamination in the runoff could result in pollution of groundwater source or resource. ▪ Soakaways must be at least 5 meters from any habitable building. Fig. 32. Cross section of a Drainage System Including a French Drain and Soakaway