2017-05-10 CC Packet - Laserfiche WebLink

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atyofCenterwIle Page 4 Downtown Storm Water Redamatbn Project 6/8/10 Balifield Soil Two samples of soil were taken from the outfield areas of the LaMotte Paris balifields (the ones to be irrigated). Soil samples from the balifield areas were taken primarily to establish background levels of certain pollutants. This will help us as we monitor the operation of the system moving forward. For instance, if the grass begins to have trouble, we can again take soil samples and determine if the levels of a certain compound are elevated over what they were before we began irrigating. Then we can address that particular problem rather than having to guess which pollutant is the issue. Additionally, if there was a human health concern, we'd be able to know whether or not it is directly related to the irrigation system. The idea being that if the levels of contaminants in the soil at the time the issue arises are no different than they were before the irrigation project was installed, it would be difficult to point the finger at the system. Below are some excerpts from various authorities outlining the background levels of certain contaminants in typical soils or the levels which can be tolerated without risk to human health. From the MN Department of Health Website: Levels of arsenic in soil from 5 ppm up to 20 ppm (5-20 mg/kg) are generally viewed as safe, even if contact with arsenic at these levels continues for many years. If the level of arsenic in soil is within this range, the potential for any health effect is very small. In fact, contact with arsenic in soil even somewhat above these levels will likely have no health effects. However, if levels do exceed this range, another risk assessment may be done that looks specifically at the site being evaluated to determine what level will be safe for that particular situation. From the U.S. Department of Health and Human Services, Public Health Service; Agency for Toxic Substances and Disease Registry (ATSDR). Copper is a reddish metal that occurs naturally in rock, soil, water, sediment and air. Its average concentration in the earth's crust is about 50 parts copper per million parts soil (ppm or mg/kg). Copper also occurs naturally in plants and animals. It is an essential element for all known living organisms including humans and other animals. From the U.S. Department of Health and Human Services, Public Health Service; Agency for Toxic Substances and Disease Registry (ATSDR). Normal soil levels [of Mercury] range from 20 to 625 parts of mercury per billion parts of soil (20-625 ppb; or 20,000-625,000 ng per kilogram of soil). A part per billion is one thousand times bigger than a part per trillion. From the PACE Turfgrass Research Institute, below are desired ranges for Chloride and pH. Chloride <400 mg/kg pH 6.5 - 7.5 standard units 107