[PDF Format] – This 15-page booklet describes how a septic system works and what a homeowner can do to help the system treat their wastewater efficiently.
…investigations,have, found fracking to be the common thread in more than 1,000 cases of water contamination across seven states, including dozens of cases of well failures in which the concrete or steel meant to protect aquifers cracked under high pressure.
Surface and groundwater supplies are also at risk since an estimated 10 to 90 percent of fracking fluid is returned to the surface during well completion and subsequent production, according to a 2011 public health report on natural gas operations.
Natural gas is mostly methane, and the potent greenhouse gas— it traps 21 times more heat than CO2— has been leaking from wells at twice the rate of fracking industry claims, according to a 2012 study published in the journal Nature…read more about these ten scariest chemicals Methanol, BTEX compounds, Diesel fuel, Lead , Hydrogen fluoride , Naphthalene , Sulfuric acid, Formaldehyde , Crystalline silica , Unknown chemicals. .
The following is courtousy of Michael Kelley | Mar. 16, 2012, 1:35 PM
Flickr/prizepony Methanol appeared most often in hydraulic fracturing products (in terms of the number of compounds containing the chemical).Found in antifreeze, paint solvent and vehicle fuel.
Vapors can cause eye irritation, headache and fatigue, and in high enough doses can be fatal. Swallowing may cause eye damage or death.
The BTEX compounds – benzene, toluene, xylene, and ethylbenzene – are listed as hazardous air pollutants in the Clean Air Act and contaminents in the Safe Drinking Water Act.
Benzene, commonly found in gasoline, is also a known human carcinogen. Long time exposure can cause cancer, bone marrow failure, or leukemia. Short term effects include dizziness, weakness, headache, breathlessness, chest constriction, nausea, and vomiting. Toluene, ethylbenzene, and xylenes have harmful effects on the central nervous system. The hydraulic fracturing companies injected 11.4 million gallons of products containing at least one BTEX chemical between 2005 and 2009.
A carcinogen listed as a hazardous air pollutant under the Clean Air Act and a contaminant in the Safe Drinking Water Act.
In its 2004 report, the EPA stated that the “use of diesel fuel in fracturing fluids poses the greatest threat” to underground sources of drinking water.
Hydraulic fracturing companies injected more than 30 million gallons of diesel fuel or hydraulic fracturing fluids containing diesel fuel in wells in 19 states.
Diesel fuel contains toxic constituents, including BTEX compounds. Contact with skin may cause redness, itching, burning, severe skin damage and cancer. (Kerosene is also used. Found in jet and rocket fuel, the vapor can cause irritation of the eyes and nose, and ingestion can be fatal. Chronic exposure may cause drowsiness, convulsions, coma or death.)
A carcinogen found in paint, building construction materials and roofing joints.
It is listed as a hazardous air pollutant in the Clean Air Act and a contaminant in the Safe Drinking Water Act.
Lead is particularly harmful to children’s neurological development. It also can cause reproductive problems, high blood pressure, and nerve disorders in adults.
Flickr/Molly Des Jardin
Found in rust removers, aluminum brighteners and heavy duty cleaners. Listed as a hazardous air pollutant in the Clean Air Act.
Fumes are highly irritating, corrosive, and poisonous. Repeated ingestion over time can lead to hardening of the bones, and contact with liquid can produce severe burns. A lethal dose is 1.5 grams.
Absorption of substantial amounts of hydrogen fluoride by any route may be fatal.
A carcinogen found in lead-acid batteries for cars.
Corrosive to all body tissues. Inhalation may cause serious lung damage and contact with eyes can lead to a total loss of vision. The lethal dose is between 1 teaspoonful and one-half ounce.
A carcinogen found in concrete, brick mortar and construction sands.
Dust is harmful if inhaled repeatedly over a long period of time and can lead to silicosis or cancer.
A carcinogen found in embalming agents for human or animal remains.
Ingestion of even one ounce of liquid can cause death. Exposure over a long period of time can cause lung damage and reproductive problems in women.
“Many of the hydraulic fracturing fluids contain chemical components that are listed as ‘proprietary’ or ‘trade secret.’ The companies used 94 million gallons of 279 products that contained at least one chemical or component that the manufacturers deemed proprietary or a trade secret. In many instances, the oil and gas service companies were unable to identify these ‘proprietary’ chemicals,suggesting that the companies are injecting fluids containing chemicals that they themselves cannot identify.
Last updated June 5th 2012 From Wikipedia, the free encyclopedia
Proppants and fracking fluids
Last updated June 5th 2012 From Wikipedia, the free encyclopedia
A proppant is a material that will keep a induced hydraulic fracture open, during or following a fracturing treatment, while the fracking fluid itself varies in composition depending on the type of fracturing used, and can be gel, foam or slickwater-based. In addition, there may be unconventional fracking fluids. Fluids make tradeoffs in such material properties as viscosity, where more viscous fluids can carry more concentrated proppant; the energy or pressure demands to maintain a certain flux pump rate (flow velocity) that will conduct the proppant appropriately; pH, various rheological factors, among others. In addition, fluids may be used in low-volume well stimulation of high-permeability sandstone wells (20k to 80k gallons per well) to the high-volume operations such as shale gas and tight gas that use millions of gallons of water per well.
Conventional wisdom has often vascillated about the relative superiority of gel, foam and slickwater fluids with respect to each other, which is in turn related to proppant choice. For example, Zuber, Kuskraa and Sawyer (1988) found that gel-based fluids seemed to achieve the best results for coalbed methane operations, , but as of 2012, slickwater treatments are more popular.
Ignoring proppant, slickwater fracturing fluids are mostly water, generally 99% or more by volume, but gel-based fluids can see polymers and surfactants comprising as much as 7 vol% of a gel-based fluid, ignoring other additives.  Other common additives include hydrochloric acid (low pH can etch certain rocks, dissolving limestone for instance), friction reducers, biocides, and emulsifiers.
Radioactive tracer isotopes are sometimes included in the hydrofracturing fluid to determine the injection profile and location of fractures created by hydraulic fracturing. Patents describe in detail how several tracers are typically used in the same well. Wells are hydraulically fractured in different stages. Tracers with different half-lives are used for each stage. Their half-lives range from 40.2 hours (Lanthanum-140) to 5.27 years (Cobalt-60). Amounts per injection of radionuclide are listed in the The US Nuclear Regulatory Commission (NRC) guidelines.The NRC guidelines also list a wide range or radioactive materials in solid, liquid and gaseous forms that are used as field flood or enhanced oil and gas recovery study applications tracers used in single and multiple wells.
Except for diesel-based additive fracturing fluids, noted by the American Environmental Protection Agency to have a higher proportion of volatile organic compounds and carcinogenic BTEX, use of fracturing fluids in hydraulic fracturing operations was explicitly excluded from regulation under the American Clean Water Act in 2005, a legislative move that has since attracted controversy for being the product of special interests lobbying.
Proppants used should be permeable or permittive to gas under high pressures; the interstitial space between particles should be sufficiently large, yet have the mechanical strength to withstand closure stresses to hold fractures open after the fracturing pressure is withdrawn. Large mesh proppants have greater permeability than small mesh proppants at low closure stresses, but will mechanically fail (i.e. get crushed) and produce very fine particulates (“fines”) at high closure stresses such that smaller-mesh proppants overtake large-mesh proppants in permeability after a certain threshold stress.
Though sand is a common proppant, untreated sand is prone to significant fines generation; fines generation is often measured in wt% of initial feed. A commercial newsletter from Hexion cites untreated sand fines production to be 23.9% compared with 8.2% for lightweight ceramic and 0.5% for their product.  One way to maintain an ideal mesh size (i.e. permeability) while having sufficient strength is to choose proppants of sufficient strength; sand might be coated with resin, or a different proppant material might be chosen altogether– popular alternatives include ceramic, glass, and sintered bauxite.
Increased strength often comes at a cost of increased density, which in turn demands higher flow rates, viscosities or pressures during fracturing, which translates to increased fracturing costs, both environmentally and economically.  Lightweight proppants conversely are designed to be lighter than sand (~2.5 g/cc) and thus allow pumping at lower pressures or fluid velocities. Light proppants are less likely to settle. Porous materials can break the strength-density trend, or even afford greater gas permeability. Proppant geometry is also important; certain shapes or forms amplify stress on proppant particles making them especially vulnerable to crushing (a sharp discontinuity can classically allow infinite stresses in linear elastic materials). 
Proppant mesh size also impacts fracture length: proppants can be “bridged out” if the fracture width decreases to less than twice the size of the diameter of the proppant.  As proppants are deposited in a fracture, proppants can resist further fluid flow or the flow of other proppants, inhibiting further growth of the fracture. In addition, closure stresses (once external fluid pressure is released) may cause proppants to reorganise or “squeeze out” proppants, even if no fines are generated, resulting in smaller effective width of the fracture and decreased permeability. Some companies try to cause weak bonding at rest between proppant particles in order to prevent such reorganisation.  The modelling of fluid dynamics and rheology of fracturing fluid and its carried proppants is a subject of active research by the industry.
Though good proppant choice positively impacts output rate and overall ultimate recovery of a well; commercial proppants are also constrained by cost. Transport costs from supplier to site form a significant component of the cost of proppants.