1987-11-25 MN Water Analysis Report

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MINNESOTA DEPARTMENT OF HEALTH WATER QUALITY PARAMETERS VOLATILE ORGANIC CHEMICALS (VOC's) are a large group of low boiling point. carbon -containing. predomi- nantly manmade substances. VOC's are contained in a wide variety of industrial. commercial. and resi- dential products including: cleaners. degreasers. paints. solvents, inks, and petroleum distillates. VOC's do not normally occur in groundwater. Their presence usually signifies contamination from improper use. storage. disposal. spillage or leakage of solvents or petroleum products. VOC's vary widely in their toxicity and drinking water concentration standards. NITRATE AND NITRITE NITROGEN is used as one of the principal indicators of water quality. Nitrate is t..e stable form of nitrogen in oxygenated groundwater. Nitrite presents a particular health threat to infants. Sources of nitrogen include: municipal and industrial wastes. landfill leachate, animal and human wastes. nitrogen fertilizers. decomposition of organic matter and dissolution of nitrogen - containing soil and rocks. Background concentrations* in Minnesota groundwaters range from less than 0.4 milligrams per liter (mg/1) to 140 mg/l with a mean of 2.7 mg/l. A primary drinking water standard Of 10 09/1 has been established for public water supplies. AMnNIA. a compound of nitrogen and hydrogen. is generally found in low concentrations in groundwater due to oxidation to nitrate and adsorption to soil particles. High concentrations of ammonia may represent oxygen depleted water or rapid introduction of ammonia fertilizers. animal or human wastes. or leaching of solid wastes. CHLORIDE is one of the major inorganic anions in water. Chloride is very soluble and will move through groundwater with little attenuation. The presence of chloride in groundwater may be due to natural salts in soils or rocks. or leaching of chemical fertilizers. solid wastes or highway deicing salts. Background chloride concentrations in Minnesota groundwaters range from 0.3 mg/l to 490 mg/l. with a mean of 19.2 mg/1. The secondary drinking water standard (recommended guideline) for public water supplies is 2SO mg/l. SULPHATE occurs almost universally in groundwater. Rainfall may contain 10 mg/l or more sulphate. Household wastes, including detergents. may add 10 mg/l or more sulphate to sewage. The usual source in groundwater is naturally occurring sulphates of gypsum or anhydrite. Background concentrations Of sulphate in Minnesota groundwaters range from 0.5 09/1 to 1300 09/1 with a mean of 72 mg/l. The secondary drinking water standard for public water supplies is 250 mg/l. IRON is a commonly found constituent in groundwaters, primarily derived from weathering of soil and rocks. High concentrations can be due to corrosive water or leaching of wastes. Background concen- trations in Minnesota groundwaters range from less than 0.03 mg/l to 46 mg/l with a mean of 1.3 mg/l. The secondary drinking water standard for public water supplies is 0.3 mg/l. SPECIFIC CONDUCTANCE is a measure of the ability of water to conduct an electric current. This ability depends on the presence. concentration. and chemical state of ions. Uastewater and leachate typically have high concentrations of dissolved .material (ions) and therefore high specific conductance. Back- ground specific conductance in Minnesota .groundwaters ranges from 50 to 2500 micromhos per centimeter (weho/cm) with a mean of 630 ymho/cm. Spetif'.c conductance is often used to estimate total dissolved solids (TDS) by multiplying specific conductance by .6. The secondary drinking water standard for Public water supplies is SOO mg/l TDS. PH is a measure of the hydrogen ion activity of water. pH less than 7 represents acid conditions. PH greater than 7 represents alkaline or basic conditions. Background pH levels in Minnesota ground - waters range from 5.9 to 9.4 with a mean of 7.5. The se.-.ondary drinking water standard for public water supplies is 6.5 to 6.5. 'Background concentrations represent water quality values from 410 wells .end springs sampled throughout Minnesota in the Minnesota Pollution Control Agency's Ground Water Quality K,nitorinq Program.