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56-429: FCWA does not provide sanitary sewer service; this is left to the individual jurisdictions it serves. FCWA traces its history back to the 1950s. At the time, Fairfax County was a mostly rural county that was quickly becoming suburban, and was served by a number of small, privately owned water companies and private wells. This posed a problem in the first half of the decade, as hot summers and increased demand often caused

112-556: A "thermal bridge" that degrades thermal performance. Also, since steel does not have the same thermal expansion coefficient as concrete, as the wall heats and cools any steel that is not embedded in the concrete can create thermal stresses that cause cracking and spalling. To achieve better thermal performance, insulation was added in the void, and in many applications today the steel trusses have been replaced by composite (fibreglass, plastic, etc.) connection systems. These systems, which are specially developed for this purpose, also eliminate

168-668: A building's enclosure or "envelope," they can be designed to also serve as part of the building's structural system, eliminating the need for beams and columns on the building perimeter. Besides their energy efficiency and aesthetic versatility, they also provide excellent noise attenuation, outstanding durability (resistant to rot, mold, etc.), and rapid construction. In addition to the good insulation properties, sandwich panels require fewer work phases to complete. Compared to double-walls, for example, which have to be insulated and filled with concrete on site, sandwich panels require much less labor and scaffolding. The precast concrete industry

224-869: A construction site. The forms used in a precast plant can be reused hundreds to thousands of times before they have to be replaced, often making it cheaper than onsite casting in terms of cost per unit of formwork. Precast concrete forming systems for architectural applications differ in size, function, and cost. Precast architectural panels are also used to clad all or part of a building facade or erect free-standing walls for landscaping, soundproofing , and security. In appropriate instances precast products – such as beams for bridges, highways, and parking structure decks – can be prestressed structural elements. Stormwater drainage, water and sewage pipes, and tunnels also make use of precast concrete units. Precast concrete molds can be made of timber, steel, plastic, rubber, fiberglass, or other synthetic materials, with each giving

280-591: A lawsuit from a group of subscribers, who were upset that the move may increase their water rates. FCWA has since expanded its filtration capacity several times, with the introduction of new plants at Lorton and Occoquan in the 1960s, and a new plant near Herndon, Virginia in 1982, the Corbalis plant, celebrating 40 years of operation in 2022. The Griffith plant in Lorton, Virginia opened in 2006. Fairfax Water and Vulcan Materials have entered an agreement to construct

336-509: A medium-sized utility in the heart of Fairfax that, by 1955, served about 3000 homes at the time and had severe problems with water supply. Alexandria was interested in buying Alexandria Water (a privately owned system controlled by American Water Works Company ) and its Virginia Water subsidiary, citing its own water supply problems. By the end of the summer, Fairfax was ready to buy the Annandale system when they were blocked from doing so by

392-409: A precast plant), the precast concrete is afforded the opportunity to properly cure and be closely monitored by plant employees. Using a precast concrete system offers many potential advantages over onsite casting. Precast concrete production can be performed on ground level, which maximizes safety in its casting. There is greater control over material quality and workmanship in a precast plant compared to

448-710: A reservoir in Lorton, a phased project expected to be completed by 2085. Sanitary sewer A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings (but not stormwater ) to a sewage treatment plant or disposal. Sanitary sewers are a type of gravity sewer and are part of an overall system called a "sewage system" or sewerage . Sanitary sewers serving industrial areas may also carry industrial wastewater . In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. An advantage of sanitary sewer systems

504-505: A treatment plant. Force mains are typically constructed of welded steel or HDPE jointed to resist pressures within the pipe. Force mains are substantially different from pressure sewers which serve individual properties or groups of properties and provide a means of injecting sewage into a local gravity main. Effluent sewer systems, also called septic tank effluent drainage (STED) or solids-free sewer (SFS) systems, have septic tanks that collect sewage from residences and businesses, and

560-459: A unique finish. In addition, many surface finishes for the four precast wall panel types – sandwich, plastered sandwich, inner layer and cladding panels – are available, including those creating the looks of horizontal boards and ashlar stone . Color may be added to the concrete mix, and the proportions and size aggregate also affect the appearance and texture of finished concrete surfaces. Ancient Roman builders made use of concrete and soon poured

616-477: Is a huge energy consuming industry, and precast concrete products are and will continue to be more energy efficient than its counterparts. The wide range of designs, colours, and structural options that these products provide is also making it a favourable choice for its consumers. Many state and federal transportation projects in the United States require precast concrete suppliers to be certified by either

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672-418: Is a pumped sewer that may be necessary where gravity sewers serve areas at lower elevations than the sewage treatment plant, or distant areas at similar elevations. A lift station is a sewer sump that lifts accumulated sewage to a higher elevation. They may also be used to prime an inverted siphon used to cross underneath rivers or other obstructions. The pump may discharge to another gravity sewer or directly to

728-426: Is also used for the roll ways of some rubber-tyred metros . Modular paving is available in a rainbow of colors, shapes, sizes, and textures. These versatile precast concrete pieces can be designed to mimic brick, stone or wood. Underground vaults or mausoleums require watertight structures that withstand natural forces for extended periods of time. Storage of hazardous material, whether short-term or long-term,

784-407: Is an increasingly important environmental issue, calling for containers that not only seal in the materials, but are strong enough to stand up to natural disasters or terrorist attacks. Seawalls , floating docks, underwater infrastructure, decking, railings, and a host of amenities are among the uses of precast along the waterfront. When designed with heavy weight in mind, precast products counteract

840-607: Is complicated by making provisions to receive lateral flows without accepting undesirable infiltration from inadequately sealed junctions. Some sewers have tall vent pipes to release foul gases well up away from people. Common names for these pipes are stink pipe, stink pole, stench pipe and sewer ventilation pipe. Sanitary sewers evolved from combined sewers built where water was plentiful. Animal feces accumulated on city streets while animal-powered transport moved people and goods. Accumulations of animal feces encouraged dumping chamber pots into streets where night soil collection

896-432: Is distinguished from precast concrete by the finer aggregate used in the mixture, so the result approaches the natural product. Precast concrete is employed in both interior and exterior applications, from highway, bridge, and high-rise projects to parking structures, K-12 schools, warehouses, mixed-use, and industrial building construction. By producing precast concrete in a controlled environment (typically referred to as

952-701: Is essential that each structural component be designed and tested to withstand both the tensile and compressive loads that the member will be subjected to over its lifespan. Expanded polystyrene cores are now in precast concrete panels for structural use, making them lighter and serving as thermal insulation. Multi-storey car parks are commonly constructed using precast concrete. The constructions involve putting together precast parking parts which are multi-storey structural wall panels, interior and exterior columns, structural floors, girders, wall panels, stairs, and slabs. These parts can be large; for example, double-tee structural floor modules need to be lifted into place with

1008-459: Is largely dominated by Government initiated projects for infrastructural development. However, these are also being extensively used for residential (low and high rise) and commercial constructions because of their various favourable attributes. The efficiency, durability, ease, cost effectiveness, and sustainable properties of these products have brought a revolutionary shift in the time consumed in construction of any structure. Construction industry

1064-481: Is required to prevent inappropriate connection of cellar, yard, and roof drains to sanitary sewers. The probability of inappropriate connections is higher where combined sewers and sanitary sewers are found in close proximity, because construction personnel may not recognize the difference. Many older cities still use combined sewers while adjacent suburbs were built with separate sanitary sewers. For decades, when sanitary sewer pipes cracked or experienced other damage,

1120-506: Is that they avoid combined sewer overflows . Sanitary sewers are typically much smaller in diameter than combined sewers which also transport urban runoff . Backups of raw sewage can occur if excessive stormwater inflow or groundwater infiltration occurs due to leaking joints, defective pipes etc. in aging infrastructure. Sewage treatment is less effective when sanitary waste is diluted with stormwater, and combined sewer overflows occur when runoff from heavy rainfall or snowmelt exceeds

1176-410: Is the most common form of concrete reinforcement. It is typically made from steel, manufactured with ribbing to bond with concrete as it cures. Rebar is versatile enough to be bent or assembled to support the shape of any concrete structure. Carbon steel is the most common rebar material. However, stainless steel, galvanized steel, and epoxy coatings can prevent corrosion. The following is a sampling of

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1232-446: Is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams , and wall panels, floors, roofs, and piles. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site. Recently lightweight expanded polystyrene foam is being used as the cores of precast wall panels, saving weight and increasing thermal insulation . Precast stone

1288-460: Is typically 8 inches, but their designs are often customized to the application. In a typical 8-inch wall panel the concrete wythes are each 2-3/8 inches thick), sandwiching 3-1/4 inches of high R-value insulating foam. The interior and exterior wythes of concrete are held together (through the insulation) with some form of connecting system that is able to provide the needed structural integrity. Sandwich wall panels can be fabricated to

1344-644: The Jim Bridger Building in Williston, North Dakota, was precast in Minnesota with air, electrical, water, and fiber utilities preinstalled into the building panels. The panels were transported over 800 miles to the Bakken oilfields, and the commercial building was assembled by three workers in minimal time. The building houses over 40,000 square feet of shops and offices. Virtually the entire building

1400-703: The UK for a variety of applications including agricultural buildings, grain stores, silage clamps, slurry stores, livestock walling and general retaining walls. Panels can be used horizontally and placed either inside the webbings of RSJs ( I-beam ) or in front of them. Alternatively panels can be cast into a concrete foundation and used as a cantilever retaining wall. Precast concrete building components and site amenities are used architecturally as fireplace mantels, cladding, trim products, accessories and curtain walls. Structural applications of precast concrete include foundations, beams, floors, walls and other structural components. It

1456-461: The buoyant forces of water significantly better than most materials. Prestressing is a technique of introducing stresses into a structural member during fabrication and/or construction to improve its strength and performance. This technique is often employed in concrete beams, columns, spandrels, single and double tees, wall panels, segmental bridge units, bulb-tee girders, I-beam girders, and others. Many projects find that prestressed concrete provides

1512-481: The construction, safety, and site protection of roads, airports, and railroad transportation systems. Products include: box culverts , 3-sided culverts, bridge systems, railroad crossings, railroad ties, sound walls /barriers, Jersey barriers , tunnel segments, concrete barriers, TVCBs, central reservation barriers, bollards, and other transportation products. Precast concrete can also be used to make underpasses, surface crossings, and pedestrian subways. Precast concrete

1568-427: The developed world, sewers are pipes from buildings to one or more levels of larger underground trunk mains, which transport the sewage to sewage treatment facilities. Vertical pipes, usually made of precast concrete , called manholes , connect the mains to the surface. Depending upon site application and use, these vertical pipes can be cylindrical , eccentric , or concentric . The manholes are used for access to

1624-408: The differential thermal expansion problem. The best thermal performance is achieved when the insulation is continuous throughout the wall section, i.e., the wythes are thermally separated completely to the ends of the panel. Using continuous insulation and modern composite connection systems, R-values up to R-28.2 can be achieved. The overall thickness of sandwich wall panels in commercial applications

1680-498: The effluent that comes out of the tank is sent to either a centralized sewage treatment plant or a distributed treatment system for further treatment. Most of the solids are removed by the septic tanks, so the treatment plant can be much smaller than a typical plant. In addition, because of the vast reduction in solid waste, a pumping system, rather than a gravity system, can be used to move the wastewater. The pipes have small diameters, typically 1.5 to 4 inches (4 to 10 cm). Because

1736-405: The expected service life of the repair. Another popular method for replacing aged or damaged lines is called pipe bursting , where a new pipe, typically PVC or ABS plastic, is drawn through the old pipe behind an "expander head" that breaks apart the old pipe as the new one is drawn through behind it. These methods are most suitable for trunk sewers, since repair of lines with lateral connections

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1792-433: The help of precast concrete lifting anchor systems . Precast concrete is employed in a wide range of engineered earth retaining systems. Products include commercial and residential retaining walls , sea walls , mechanically stabilized earth panels, and other modular block systems. Sanitary and stormwater management products are structures designed for underground installation that have been specifically engineered for

1848-590: The hydraulic capacity of sewage treatment plants . To overcome these disadvantages, some cities built separate sanitary sewers to collect only municipal wastewater and exclude stormwater runoff, which is collected in separate storm drains. The decision to build a combined sewer system or two separate systems is mainly based on the need for sewage treatment and the cost of providing treatment during heavy rain events. Many cities with combined sewer systems built their systems prior to installing sewage treatment plants, and have not subsequently replaced those sewer systems. In

1904-572: The investment cost for simplified sanitary sewers can be about half the cost of conventional sewers, the requirements for operation and maintenance are usually higher. Simplified sewers are most common in Brazil and other developing countries. In low-lying communities, wastewater is often conveyed by vacuum sewer . Pipelines range in size from pipes of 125 millimetres (4.9 in) in diameter up to 280 millimetres (11 in) in diameter. Vacuum sewer systems use differential atmospheric pressure to move

1960-407: The length and width desired, within practical limits dictated by the fabrication system, the stresses of lifting and handling, and shipping constraints. Panels of 9-foot clear height are common, but heights up to 12 feet can be found. The fabrication process for precast concrete sandwich wall panels allows them to be produced with finished surfaces on both sides. Such finishes can be very smooth, with

2016-431: The liquid to a central vacuum station. Sanitary sewer overflow can occur due to blocked or broken sewer lines, infiltration of excessive stormwater or malfunction of pumps. In these cases untreated sewage is discharged from a sanitary sewer into the environment prior to reaching sewage treatment facilities. To avoid such overflows, maintenance is required. Blockage prevention campaigns or regulations (e.g. requiring

2072-452: The lowest overall cost, considering production and lifetime maintenance. The precast concrete double-wall panel has been in use in Europe for decades. The original double-wall design consisted of two wythes of reinforced concrete separated by an interior void, held together with embedded steel trusses. With recent concerns about energy use, it is recognized that using steel trusses creates

2128-552: The material into moulds to build their complex network of aqueducts , culverts , and tunnels. Modern uses for pre-cast technology include a variety of architectural and structural applications – including individual parts, or even entire building systems. In the modern world, precast panelled buildings were pioneered in Liverpool , England , in 1905. The process was invented by city engineer John Alexander Brodie . The tram stables at Walton in Liverpool followed in 1906. The idea

2184-425: The mid-20th century or later generally have built separate systems for sewage (sanitary sewers) and stormwater, because precipitation causes widely varying flows, reducing sewage treatment plant efficiency. In the UK, the term "foul sewer" was also in use for a sanitary sewer. Precast concrete Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which

2240-606: The numerous products that utilize precast/prestressed concrete. While this is not a complete list, the majority of precast/prestressed products typically fall under one or Since precast concrete products can withstand the most extreme weather conditions and will hold up for many decades of constant usage they have wide applications in agriculture. These include bunker silos, cattle feed bunks, cattle grid , agricultural fencing, H-bunks, J-bunks, livestock slats, livestock watering trough, feed troughs, concrete panels, slurry channels, and more. Prestressed concrete panels are widely used in

2296-410: The only option was an expensive excavation, removal and replacement of the damaged pipe, typically requiring street repavement afterwards. In the mid-1950s a unit was invented where two units at each end with a special cement mixture in between was pulled from one manhole cover to the next, coating the pipe with the cement under high pressure, which then cured rapidly , sealing all cracks and breaks in

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2352-575: The panels to reduce on-site construction time. The carpenters, electricians and plumbers do need to make some slight adjustments when first becoming familiar with some of the unique aspects of the wall panels. However, they still perform most of their job duties in the manner to which they are accustomed. Precast concrete sandwich wall panels have been used on virtually every type of building, including schools, office buildings, apartment buildings, townhouses, condominiums, hotels, motels, dormitories, and single-family homes. Although typically considered part of

2408-445: The pipe. Today, a similar method using epoxy resin is used by some municipalities to re-line aging or damaged pipes, effectively creating a "pipe in a pipe". These methods may be unsuitable for locations where the full diameter of the original pipe is required to carry expected flows, and may be an unwise investment if greater wastewater flows may be anticipated from population growth, increased water use, or new service connections within

2464-601: The population to be served over the anticipated life of the sewer, per capita wastewater production, and flow peaking from timing of daily routines. Minimum sewer diameters are often specified to prevent blockage by solid materials flushed down toilets; gradients may be selected to maintain flow velocities generating sufficient turbulence to minimize solids deposition within the sewer. Commercial and industrial wastewater flows are also considered, but diversion of surface runoff to storm drains eliminates wet weather flow peaks of inefficient combined sewers. A force main or rising main

2520-702: The precast concrete products industry produces utility, underground, and other non-prestressed products, and is represented primarily by the National Precast Concrete Association (NPCA). In Australia , The New South Wales Government Railways made extensive use of precast concrete construction for its stations and similar buildings. Between 1917 and 1932, it erected 145 such buildings. Beyond cladding panels and structural elements, entire buildings can be assembled from precast concrete. Precast assembly enables fast completion of commercial shops and offices with minimal labor. For example,

2576-405: The purpose of further processing into non-contaminating liquids and soil products. Products include: aeration systems , distribution boxes, dosing tanks, dry wells , grease interceptors , leaching pits, sand-oil/oil-water interceptors, septic tanks , water/sewage storage tanks, wet wells, fire cisterns, and other water and wastewater products. Precast concrete transportation products are used in

2632-571: The sewer pipes for inspection and maintenance, and as a means to vent sewer gases. They also facilitate vertical and horizontal angles in otherwise straight pipelines. Pipes conveying sewage from an individual building to a common gravity sewer line are called laterals. Branch sewers typically run under streets receiving laterals from buildings along that street and discharge by gravity into trunk sewers at manholes. Larger cities may have sewers called interceptors , receiving flow from multiple trunk sewers. Design and sizing of sanitary sewers considers

2688-446: The surfaces painted, stained, or left natural; for interior surfaces, the finish is comparable to drywall in smoothness and can be finished using the same prime and paint procedure as is common for conventional drywall construction. If desired, the concrete can be given an architectural finish, where the concrete itself is colored and/or textured. Colors and textures can provide the appearance of brick, stone, wood, or other patterns through

2744-795: The treatment and removal of pollutants from sanitary and stormwater run-off. These precast concrete products include stormwater detention vaults , catch basins , and manholes . For communications, electrical, gas or steam systems, precast concrete utility structures protect the vital connections and controls for utility distribution. Precast concrete is nontoxic and environmentally safe. Products include: hand holes, hollow-core products, light pole bases, meter boxes, panel vaults, pull boxes, telecommunications structures, transformer pads, transformer vaults, trenches, utility buildings, utility vaults , utility poles, controlled environment vaults (CEVs), and other utility structures. Precast water and wastewater products hold or contain water, oil or other liquids for

2800-551: The use of grease interceptors by some customers) may also be necessary. The maintenance requirements vary with the type of sanitary sewer. In general, all sewers deteriorate with age, but infiltration and inflow are problems unique to sanitary sewers, since both combined sewers and storm drains are sized to carry these contributions. Holding infiltration to acceptable levels requires a higher standard of maintenance than necessary for structural integrity considerations of combined sewers. A comprehensive construction inspection program

2856-504: The use of reusable formliners , or, in the most sophisticated applications, actual brick, stone, glass, or other materials can be cast into the concrete surface. Window and door openings are cast into the walls at the manufacturing plant as part of the fabrication process. In many applications, electrical and telecommunications conduit and boxes are cast directly into the panels in the specified locations. In some applications, utilities, plumbing and even heating components have been cast into

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2912-591: The waste stream is pressurized, they can be laid just below the ground surface along the land's contour. Where it is impossible or impractical to discharge sewage from a property into a gravity sanitary sewer, a pressure sewer may provide an alternative means of connection. A macerator pump in a pumping well close to the property ejects sewage through a small diameter high pressure pipe into the nearest gravity sewer. Simplified sanitary sewers consist of small-diameter pipes, typically around 100 millimetres (4 in), often laid at fairly flat gradients (1 in 200). Although

2968-552: The wells to run dry. The Alexandria Water Company , which served Alexandria, Virginia and its immediate suburbs, had opened a treatment plant on the Occoquan River near Occoquan, Virginia in 1954, but even that wasn't enough, and both the county government and the city of Alexandria were looking for a solution to the problem together. Fairfax became interested in buying the Annandale Water Company ,

3024-492: Was fabricated in Minnesota. Reinforcing concrete with steel improves strength and durability. On its own, concrete has good compressive strength, but lacks tensile and shear strength and can be subject to cracking when bearing loads for long periods of time. Steel offers high tensile and shear strength to make up for what concrete lacks. Steel behaves similarly to concrete in changing environments, which means it will shrink and expand with concrete, helping avoid cracking. Rebar

3080-409: Was impractical. Combined sewers were built to use surface runoff to flush waste off streets and move it underground to places distant from populated areas. Sewage treatment became necessary as population expanded, but increased volumes and pumping capacity required for treatment of diluted waste from combined sewers is more expensive than treating undiluted sewage. Communities that have urbanized in

3136-955: Was not taken up extensively in Britain. However, it was adopted all over the world, particularly in Central and Eastern Europe as well as in Million Programme in Scandinavia. In the US, precast concrete has evolved as two sub-industries, each represented by a major association. The precast concrete structures industry, represented primarily by of the Precast/Prestressed Concrete Institute (PCI), focuses on prestressed concrete elements and on other precast concrete elements used in above-ground structures such as buildings, parking structures, and bridges, while

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