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60-604: The peninsula runs between Castro Cove and Point San Pablo , and is dominated by the steep ridges of the Potrero Hills , an escarpment that runs along the entire peninsula. The peninsula is largely owned by Chevron and is used as a safety buffer for security purposes (see Chevron Richmond Refinery ). Features located on San Pablo Peninsula include: 37°56′09″N 122°20′52″W  /  37.93583°N 122.34778°W  / 37.93583; -122.34778 This Contra Costa County, California –related article

120-840: A catalyst for converting polyethylene into substance similar to crude oil in a high-temperature process called pyrolysis and utilized in waste water treatment. In addition, fly ash, mainly class C, may be used in the stabilization/solidification process of hazardous wastes and contaminated soils. For example, the Rhenipal process uses fly ash as an admixture to stabilize sewage sludge and other toxic sludges. This process has been used since 1996 to stabilize large amounts of chromium(VI) contaminated leather sludges in Alcanena , Portugal. The majority of CCPs are landfilled, placed in mine shafts or stored in ash ponds at coal-fired power plants. Groundwater pollution from unlined ash ponds has been

180-424: A 20-acre (81,000 m ) portion was designated as an area of concern (AOC). The most contaminated, AOC is adjacent to the former wastewater outfall which has been relocated into San Pablo Bay . A California Environmental Quality Act (CEQA)-mandated mitigated negative declaration was completed and a corrective action plan was designed. The plan which includes a natural resource damage assessment will cordon off

240-478: A component in geopolymers , where the reactivity of the fly ash glasses can be used to create a binder similar to a hydrated Portland cement in appearance, but with potentially superior properties, including reduced CO 2 emissions, depending on the formulation. Another application of using fly ash is in roller compacted concrete dams. Many dams in the US have been constructed with high fly ash contents. Fly ash lowers

300-457: A continuing environmental problem in the United States. Additionally some of these ponds have had structural failures, causing massive ash spills into rivers, such as the 2014 Dan River coal ash spill . Federal design standards for ash ponds were strengthened in 2015. Following litigation challenges to various provisions of the 2015 regulations, EPA issued two final rules in 2020, labeled as

360-463: A decrease in hydraulic conductivity and cohesiveness. The effect of fly ash on soils and microorganisms in the soils are influenced by the pH of the ash and trace metal concentrations in the ash. Microbial communities in contaminated soil have shown reductions in respiration and nitrification. These contaminated soils can be detrimental or beneficial to plant development. Fly ash typically has beneficial outcomes when it corrects nutrient deficiencies in

420-453: A filler material. High fly ash content mixes contain nearly all fly ash, with a small percentage of Portland cement and enough water to make the mix flowable. Low fly ash content mixes contain a high percentage of filler material, and a low percentage of fly ash, Portland cement, and water. Class F fly ash is best suited for high fly ash content mixes, whereas Class C fly ash is almost always used in low fly ash content mixes. Asphalt concrete

480-486: A kiln at about 1000 °C. This approach has the principal benefit of reducing the amount of clay required. Another type of fly ash brick is made by mixing soil, plaster of Paris, fly ash and water, and allowing the mixture to dry. Because no heat is required, this technique reduces air pollution. More modern manufacturing processes use a greater proportion of fly ash, and a high pressure manufacturing technique, which produces high strength bricks with environmental benefits. In

540-497: A large uniformity coefficient and it consists of clay-sized particles. Engineering properties that affect the use of fly ash in embankments include grain size distribution, compaction characteristics , shear strength , compressibility , permeability , and frost susceptibility . Nearly all the types of fly ash used in embankments are Class F. Soil stabilization is the permanent physical and chemical alteration of soils to enhance their physical properties. Stabilization can increase

600-884: A report by the Environmental Integrity Project , Earthjustice , the Prairie Rivers Network, and the Sierra Club . Tennessee In 2008, the Kingston Fossil Plant in Roane County spilled 1.1 billion gallons of coal ash into the Emory and Clinch Rivers and damaged nearby residential areas. It is the largest industrial spill in the U.S. Groundwater surrounding every single one of the 16 coal-burning power plants in Texas has been polluted by coal ash, according to

660-560: A study by the Environmental Integrity Project (EIP). Unsafe levels of arsenic, cobalt, lithium, and other contaminants were found in the groundwater near all the ash dump sites. At 12 of the 16 sites, the EIP analysis found levels of arsenic in the groundwater 10 times higher than the EPA Maximum Contaminant Level ; arsenic has been found to cause several types of cancer. At 10 of the sites, lithium, which causes neurological disease,

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720-550: Is a stub . You can help Misplaced Pages by expanding it . Castro Cove Castro Cove is a "portion of the San Pablo Bay " in Richmond, California located between Point San Pablo and the confluence of Wildcat Creek into Castro Creek . The cove is made up of mudflats , bay mud , and intertidal salt marsh owned by Chevron USA . The cove forms an important estuarine environmental resource for San Francisco Bay . It

780-444: Is a composite material consisting of an asphalt binder and mineral aggregate commonly used to surface roads. Both Class F and Class C fly ash can typically be used as a mineral filler to fill the voids and provide contact points between larger aggregate particles in asphalt concrete mixes. This application is used in conjunction, or as a replacement for, other binders (such as Portland cement or hydrated lime). For use in asphalt pavement,

840-606: Is an important component of any stabilization project. This allows for the establishment of design criteria, and determination of the proper chemical additive and admixture rate that achieves the desired engineering properties. Stabilization process benefits can include: Higher resistance (R) values, Reduction in plasticity, Lower permeability, Reduction of pavement thickness, Elimination of excavation – material hauling/handling – and base importation, Aids compaction, Provides "all-weather" access onto and within projects sites. Another form of soil treatment closely related to soil stabilization

900-424: Is disposed of in landfills and ash ponds . Ash that is stored or deposited outdoors can eventually leach toxic compounds into underground water aquifers. For this reason, much of the current debate around fly ash disposal revolves around creating specially lined landfills that prevent the chemical compounds from being leached into the ground water and local ecosystems. Since coal was the dominant energy source in

960-415: Is generally included in the range 0.01–1 ppm for bituminous coal. The concentrations of other trace elements vary as well according to the kind of coal combusted to form it. Two classes of fly ash are defined by American Society for Testing and Materials (ASTM) C618: Class F fly ash and Class C fly ash. The chief difference between these classes is the amount of calcium, silica, alumina, and iron content in

1020-654: Is located on the western coast of the cove. The Chevron Richmond Refinery located at the south end of the inlet dumps 5.6 million gallons daily of treated industrial use waters into the Cove , Castro Creek and San Pablo Bay . From 1902 until 1987 the refinery released various contaminants in its wastewater and other run-off, which severely contaminated the Bay mud of the cove. In 1998 the California Regional Water Quality Control Board began to plan cleanup of

1080-433: Is produced, as well as the proportion of fly ash to bottom ash in the waste product. This is due to the different chemical make-up of the coal based on the geology of the area the coal is found and the burning process of the coal in the power plant. When the coal is combusted, it creates an alkaline dust. This alkaline dust can have a pH ranging from 8 to as high as 12. Fly ash dust can be deposited on topsoil increasing

1140-516: Is soil modification, sometimes referred to as "mud drying" or soil conditioning. Although some stabilization inherently occurs in soil modification, the distinction is that soil modification is merely a means to reduce the moisture content of a soil to expedite construction, whereas stabilization can substantially increase the shear strength of a material such that it can be incorporated into the project's structural design. The determining factors associated with soil modification vs soil stabilization may be

1200-553: Is the home of many endangered species including the Salt Marsh Harvest Mouse , Ridgway's rail , steelhead , and Olympia Oyster . Other benthic invertebrates, mammals, fish, and birds also live in the habitat; all the animals may have been injured by contamination, whether endangered or of least concern . Castro Cove is named after Don Víctor Castro . The cove is also a recreational, fishing, boating, and shellfishing area. The Richmond Rod & Gun Club Yacht Harbor

1260-509: Is used as a replacement for Portland cement in concrete . The use of fly ash as a pozzolanic ingredient was recognized as early as 1914, although the earliest noteworthy study of its use was in 1937. Roman structures such as aqueducts or the Pantheon in Rome used volcanic ash or pozzolana (which possesses similar properties to fly ash) as pozzolan in their concrete. As pozzolan greatly improves

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1320-514: Is used as self-leveling, self-compact backfill material in lieu of compacted earth or granular fill. The strength of flowable fill mixes can range from 50 to 1,200 lbf/in (0.3 to 8.3 MPa ), depending on the design requirements of the project in question. Flowable fill includes mixtures of Portland cement and filler material, and can contain mineral admixtures. Fly ash can replace either the Portland cement or fine aggregate (in most cases, river sand) as

1380-399: Is used in an optimal way to replace cement in concrete production, it must be processed using beneficiation methods like mechanical air classification. But if fly ash is used as a filler to replace sand in concrete production, unbeneficiated fly ash with higher LOI can be also used. Especially important is the ongoing quality verification. This is mainly expressed by quality control seals like

1440-626: The Bureau of Indian Standards mark or the DCL mark of the Dubai Municipality. In the past, fly ash produced from coal combustion was simply entrained in flue gases and dispersed into the atmosphere. This created environmental and health concerns that prompted laws in heavily industrialized countries like the United States that have reduced fly ash emissions to less than 1% of ash produced. Worldwide, more than 65% of fly ash produced from coal power stations

1500-686: The "CCR Part A" and "CCR Part B" rules. The rules require some facilities to retrofit their impoundments with liners, while other facilities may propose alternative designs and request additional time to achieve compliance. In March 2023 published a proposed rule that would strengthen wastewater limits for discharges to surface waters. Coal contains trace levels of trace elements (such as arsenic , barium , beryllium , boron , cadmium , chromium , thallium , selenium , molybdenum and mercury ), many of which are highly toxic to humans and other life. Therefore, fly ash obtained after combustion of this coal contains enhanced concentrations of these elements and

1560-880: The AOC with steel sheet piling and have the contaminated muds and sediment dredged and pumped into a disused treatment pond. In that treatment pond the toxic waste will be dried and then neutralized with a stabilizing agent like fly ash or cement. The inactive pond will then be regraded and capped with vegetation. The remediation project is scheduled for the summer of 2007. 37°57′22″N 122°24′04″W  /  37.956°N 122.401°W  / 37.956; -122.401 Fly ash Coal combustion products ( CCP s), also called coal combustion wastes (CCWs) or coal combustion residuals (CCRs), are categorized in four groups, each based on physical and chemical forms derived from coal combustion methods and emission controls: Fly ash , flue ash , coal ash , or pulverised fuel ash (in

1620-1116: The American Coal Ash Association. Coal ash uses include (approximately in order of decreasing importance): Other applications include cosmetics , toothpaste , kitchen counter tops, floor and ceiling tiles, bowling balls , flotation devices, stucco , utensils, tool handles, picture frames, auto bodies and boat hulls , cellular concrete, geopolymers , roof tiles , roofing granules, decking, fireplace mantles , cinder block , PVC pipe , structural insulated panels , house siding and trim, running tracks, blasting grit, recycled plastic lumber , utility poles and crossarms, railway sleepers , highway noise barriers , marine pilings , doors, window frames, scaffolding, sign posts, crypts, columns, railroad ties, vinyl flooring, paving stones, shower stalls, garage doors, park benches, landscape timbers, planters, pallet blocks, molding, mail boxes, artificial reef , binding agent, paints and undercoatings, metal castings , and filler in wood and plastic products. Owing to its pozzolanic properties, fly ash

1680-527: The CCPs such as arsenic, beryllium, boron, cadmium, chromium, chromium VI, cobalt, lead, manganese, mercury, molybdenum, selenium, strontium, thallium, and vanadium, along with dioxins and polycyclic aromatic hydrocarbons . There is no US governmental registration or labelling of fly ash utilization in the different sectors of the economy – industry, infrastructures and agriculture. Fly ash utilization survey data, acknowledged as incomplete, are published annually by

1740-644: The Environment issued a fine of $ 1 million to Constellation. Nearby residents filed a lawsuit against Constellation and in 2008 the company settled the case for $ 54 million. In 2014, residents living near the Buck Steam Station in Dukeville, North Carolina , were told that "coal ash pits near their homes could be leaching dangerous materials into groundwater". Illinois has many coal ash dumpsites with coal ash generated by coal-burning electric power plants. Of

1800-566: The Ghatghar dam project in Maharashtra, India. Due to the spherical shape of fly ash particles, it can increase workability of cement while reducing water demand. Proponents of fly ash claim that replacing Portland cement with fly ash reduces the greenhouse gas "footprint" of concrete, as the production of one ton of Portland cement generates approximately one ton of CO 2 , compared to no CO 2 generated with fly ash. New fly ash production, i.e.,

1860-515: The UK)— plurale tantum : coal combustion residuals ( CCRs )—is a coal combustion product that is composed of the particulates that are driven out of coal-fired boilers together with the flue gases . Ash that falls to the bottom of the boiler's combustion chamber (commonly called a firebox) is called bottom ash . In modern coal-fired power plants , fly ash is generally captured by electrostatic precipitators or other particle filtration equipment before

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1920-561: The United Kingdom, fly ash has been used for over fifty years to make concrete building blocks . They are widely used for the inner skin of cavity walls . They are naturally more thermally insulating than blocks made with other aggregates. Ash bricks have been used in house construction in Windhoek, Namibia , since the 1970s. There is, however, a problem with the bricks in that they tend to fail or produce unsightly pop-outs. This happens when

1980-722: The United States for many decades, power companies often located their coal plants near metropolitan areas. Compounding the environmental issues, the coal plants need significant amounts of water to operate their boilers, leading coal plants (and later their fly ash storage basins) to be located near metropolitan areas and near rivers and lakes which are often used as drinking supplies by nearby cities. Many of those fly ash basins were unlined and also at great risk of spilling and flooding from nearby rivers and lakes. For example, Duke Energy in North Carolina has been involved in several major lawsuits related to its coal ash storage and spills into

2040-411: The United States. Seventy-five percent of the fly ash must have a fineness of 45 μm or less, and have a carbon content, measured by the loss on ignition (LOI), of less than 4%. In the US, LOI must be under 6%. The particle size distribution of raw fly ash tends to fluctuate constantly, due to changing performance of the coal mills and the boiler performance. This makes it necessary that, if fly ash

2100-425: The ash. The chemical properties of the fly ash are largely influenced by the chemical content of the coal burned (i.e., anthracite , bituminous , and lignite ). Not all fly ashes meet ASTM C618 requirements, although depending on the application, this may not be necessary. Fly ash used as a cement replacement must meet strict construction standards, but no standard environmental regulations have been established in

2160-532: The bricks come into contact with moisture and a chemical reaction occurs causing the bricks to expand. In India, fly ash bricks are used for construction. Leading manufacturers use an industrial standard known as "Pulverized fuel ash for lime-Pozzolana mixture" using over 75% post-industrial recycled waste, and a compression process. This produces a strong product with good insulation properties and environmental benefits. Fly ash particles have proved their potential as good reinforcement with aluminum alloys and show

2220-525: The burning of coal, produces approximately 20 to 30 tons of CO 2 per ton of fly ash. Since the worldwide production of Portland cement is expected to reach nearly 2 billion tons by 2010, replacement of any large portion of this cement by fly ash could significantly reduce carbon emissions associated with construction, as long as the comparison takes the production of fly ash as a given. Fly ash properties are unusual among engineering materials. Unlike soils typically used for embankment construction, fly ash has

2280-399: The concrete's final strength and increase its chemical resistance and durability. Fly ash can significantly improve the workability of concrete. Recently, techniques have been developed to replace partial cement with high-volume fly ash (50% cement replacement). For roller-compacted concrete (RCC)[used in dam construction], replacement values of 70% have been achieved with processed fly ash at

2340-403: The demand for virgin materials that would need quarrying and cheap substitution for materials such as Portland cement . About 52 percent of CCPs in the U.S. were recycled for "beneficial uses" in 2019, according to the American Coal Ash Association. In Australia about 47% of coal ash was recycled in 2020. The chief benefit of recycling is to stabilize the environmentally harmful components of

2400-442: The exhaust gases and is collected by electrostatic precipitators or filter bags. Since the particles solidify rapidly while suspended in the exhaust gases, fly ash particles are generally spherical in shape and range in size from 0.5 μm to 300 μm. The major consequence of the rapid cooling is that few minerals have time to crystallize, and that mainly amorphous, quenched glass remains. Nevertheless, some refractory phases in

2460-457: The existing moisture content, the end use of the soil structure and ultimately the cost benefit provided. Equipment for the stabilization and modification processes include: chemical additive spreaders, soil mixers (reclaimers), portable pneumatic storage containers, water trucks, deep lift compactors, motor graders. Fly ash is also used as a component in the production of flowable fill (also called controlled low strength material, or CLSM), which

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2520-445: The federal standard for drinking water . Fly ash can contaminate surface water through erosion , surface runoff , airborne particles landing on the water surface, contaminated ground water moving into surface waters, flooding drainage , or discharge from a coal ash pond. Fish can be contaminated a couple of different ways. When the water is contaminated by fly ash, the fish can absorb the toxins through their gills. The sediment in

2580-416: The flue gases reach the chimneys. Together with bottom ash removed from the bottom of the boiler, it is known as coal ash . Depending upon the source and composition of the coal being burned, the components of fly ash vary considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO 2 ) (both amorphous and crystalline ), aluminium oxide (Al 2 O 3 ) and calcium oxide (CaO),

2640-527: The fly ash must meet mineral filler specifications outlined in ASTM D242 . The hydrophobic nature of fly ash gives pavements better resistance to stripping. Fly ash has also been shown to increase the stiffness of the asphalt matrix, improving rutting resistance and increasing mix durability. Coal and shale oil fly ashes have been used as a filler for thermoplastics that could be used for injection molding applications. More recently, fly ash has been used as

2700-400: The following elements or compounds found in trace concentrations (up to hundreds of ppm): gallium , arsenic , beryllium , boron , cadmium , chromium , hexavalent chromium , cobalt , lead , manganese , mercury , molybdenum , selenium , strontium , thallium , and vanadium , along with very small concentrations of dioxins , PAH compounds , and other trace carbon compounds. In

2760-581: The heat of hydration allowing thicker placements to occur. Data for these can be found at the US Bureau of Reclamation. This has also been demonstrated in the Ghatghar Dam Project in India . There are several techniques for manufacturing construction bricks from fly ash, producing a wide variety of products. One type of fly ash brick is manufactured by mixing fly ash with an equal amount of clay, then firing in

2820-735: The improvement of physical and mechanical properties. In particular, the compression strength, tensile strength, and hardness increase when the percentage of fly ash content is increased, whereas the density decreases. The presence of fly ash cenospheres in a pure Al matrix decreases its coefficient of thermal expansion (CTE). It may be possible to use vacuum distillation in order to extract germanium and tungsten from fly ash and recycle them. Fly ash, in view of its alkalinity and water absorption capacity, may be used in combination with other alkaline materials to transform sewage sludge into organic fertilizer or biofuel . Fly ash, when treated with sodium hydroxide , appears to function well as

2880-502: The leakage of ash into the water basin. The recycling of fly ash has become an increasing concern in recent years due to increasing landfill costs and current interest in sustainable development . As of 2017 , coal-fired power plants in the US reported producing 38.2 million short tons (34.7 × 10 ^  t) of fly ash, of which 24.1 million short tons (21.9 × 10 ^  t) were reused in various applications. Environmental benefits to recycling fly ash includes reducing

2940-420: The main mineral compounds in coal-bearing rock strata . The use of fly ash as a lightweight aggregate (LWA) offers a valuable opportunity to recycle one of the largest waste streams in the US. In addition, fly ash can offer many benefits, both economically and environmentally when utilized as a LWA. The minor constituents of fly ash depend upon the specific coal bed composition but may include one or more of

3000-409: The pH and affecting the plants and animals in the surrounding ecosystem. Trace elements, such as, iron , manganese , zinc , copper , lead , nickel , chromium , cobalt , arsenic , cadmium , and mercury , can be found at higher concentrations compared to bottom ash and the parent coal. Fly ash can leach toxic constituents that can be anywhere from one hundred to one thousand times greater than

3060-493: The past, fly ash was generally released into the atmosphere , but air pollution control standards now require that it be captured prior to release by fitting pollution control equipment . In the United States, fly ash is generally stored at coal power plants or placed in landfills. About 43% is recycled, often used as a pozzolan to produce hydraulic cement or hydraulic plaster and a replacement or partial replacement for Portland cement in concrete production. Pozzolans ensure

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3120-544: The potential of the ash to cause groundwater pollution is significant. In the US there are documented cases of groundwater pollution that followed ash disposal or utilization without the necessary protection having been put in place. Constellation Energy disposed fly ash generated by its Brandon Shores Generating Station at a former sand and gravel mine in Gambrills, Maryland , during 1996 to 2007. The ash contaminated groundwater with heavy metals. The Maryland Department of

3180-941: The pulverized coal do not melt (entirely), and remain crystalline. In consequence, fly ash is a heterogeneous material. SiO 2 , Al 2 O 3 , Fe 2 O 3 and occasionally CaO are the main chemical components present in fly ashes. The mineralogy of fly ashes is very diverse. The main phases encountered are a glass phase, together with quartz , mullite and the iron oxides hematite , magnetite and/or maghemite . Other phases often identified are cristobalite , anhydrite , free lime , periclase , calcite , sylvite , halite , portlandite , rutile and anatase . The Ca -bearing minerals anorthite , gehlenite , akermanite and various calcium silicates and calcium aluminates identical to those found in Portland cement can be identified in Ca-rich fly ashes. The mercury content can reach 1 ppm , but

3240-470: The setting of concrete and plaster and provide concrete with more protection from wet conditions and chemical attack. In the case that fly (or bottom) ash is not produced from coal, for example when solid waste is incinerated in a waste-to-energy facility to produce electricity, the ash may contain higher levels of contaminants than coal ash. In that case the ash produced is often classified as hazardous waste . Fly ash material solidifies while suspended in

3300-430: The shear strength of a soil and/or control the shrink-swell properties of a soil, thus improving the load-bearing capacity of a sub-grade to support pavements and foundations. Stabilization can be used to treat a wide range of sub-grade materials from expansive clays to granular materials. Stabilization can be achieved with a variety of chemical additives including lime, fly ash, and Portland cement. Proper design and testing

3360-543: The site and pressured Chevron. The water board used the authority of the Bay Protection and Toxic Clean-up Program to require Chevron to produce a sediment characterization work plan in 1998. Years of discharge or polluted water left the cove with high levels of polycyclic aromatic hydrocarbons (PAHs) and mercury contamination . Between 1999 and 2001 benthic toxicity tests found PAHs and mercury levels at up to 507 mg/kg and 13 mg/kg respectively at this site and

3420-599: The state's 24 coal ash dumpsites with available data, 22 have released toxic pollutants including arsenic , cobalt , and lithium , into groundwater, rivers and lakes. The hazardous toxic chemicals dumped into the water in Illinois by these coal ash dumpsites include more than 300,000 pounds of aluminum, 600 pounds of arsenic, nearly 300,000 pounds of boron, over 200 pounds of cadmium, over 15,000 pounds of manganese, roughly 1,500 pounds of selenium, roughly 500,000 pounds of nitrogen, and nearly 40 million pounds of sulfate, according to

3480-511: The strength and durability of concrete, the use of ash is a key factor in their preservation. Use of fly ash as a partial replacement for Portland cement is particularly suitable but not limited to Class C fly ashes. Class "F" fly ashes can have volatile effects on the entrained air content of concrete, causing reduced resistance to freeze/thaw damage. Fly ash often replaces up to 30% by mass of Portland cement, but can be used in higher dosages in certain applications. In some cases, fly ash can add to

3540-572: The water can also become contaminated. The contaminated sediment can contaminate the food sources for the fish, the fish can then become contaminated from consuming those food sources. This can then lead to contamination of organisms that consume these fish, such as, birds, bear, and even humans. Once exposed to fly ash contaminating the water, aquatic organisms have had increased levels of calcium , zinc, bromine , gold, cerium, chromium, selenium, cadmium, and mercury. Soils contaminated by fly ash showed an increase in bulk density and water capacity, but

3600-420: Was found in the groundwater at concentrations more than 1,000 micrograms per liter, which is 25 times the maximum acceptable level. The report concludes that the fossil fuel industry in Texas has failed to comply with federal regulations on coal ash processing, and state regulators have failed to protect the groundwater. The effect of fly ash on the environment can vary based on the thermal power plant where it

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