Storm Water Parameters: The Inside Scoop
We were recently asked about the results of one of our clients’ storm water monitoring and what those results mean. It occurred to me that while recyclers are required to monitor storm water there is not much information readily available about what causes storm water contamination, what the data means, and how you can fix a problematic result of a specific contaminant. I have prepared a brief description of each storm water parameter and how it affects the environment. Across the board, the best way to reduce the concentration of contaminants in your storm water outflow is to prevent storm water from contacting the pollutant sources. Store harmful substances indoors on a hard surface and clean up outdoor areas regularly.
Total Suspended Solids (TSS) – The TSS parameter is a way to measure particles that are suspended and transported with storm water. Sediment (particles) include dust from crushed stone, small debris and eroded soils. TSS in storm water affects its clarity and causes the water to appear cloudy or muddy. Storm water travels down drainage via creeks and streams and eventually reaches a pond or lake. When the water reaches a lake or pond the water velocity slows and the sediment is able to settle to the bottom. Sediment deposition on lake bottoms causes degraded water quality by reducing water clarity, blocking sunlight and reducing the volume of the lake or stream – causing the water body to age (fill in) more quickly. Sediment deposition in lakes and streams also increases the risk of flooding. The best way to reduce TSS is to reduce dust and areas with bare soil. A stable vegetative cover (grassy areas) not only protect the underlying soil from erosion but also slow storm water allowing TSS to settle on the site as opposed to in a lake or pond (receiving water). Keep in mind when you are purchasing crushed stone that some types of crushed stone are very dusty (53s). Purchasing stone with less dust (2s or 8s, etc.) will reduce the TSS in your storm water and improve water quality downstream.
Oil and Grease – The Oil and Grease (O&G) parameter is a measure of the amount of oil and grease present in storm water runoff. This contaminant is particularly problematic in salvage yards where there are large numbers of vehicles concentrated in relatively small areas. O&G can be observed as a film or sheen on the surface of water or as general discoloration. O&G float on the surface of water (sheen or film) and a very small quantity of oil can spread over a large amount of water. Many aquatic organisms surface to breathe. If there is a sheen or film on the water surface, some organisms’ breathing mechanism may be coated with the oil causing them to suffocate. Large numbers of small aquatic organisms dying from lack of air can greatly impact aquatic food chains causing fish and water fowl to suffer and/or die. Reducing the amount of oil and grease in storm water is accomplished by preventing storm water from contacting these products. Store fluids containers under roof on an impermeable surface, drain vehicles before storing them on your yard, and if a spill occurs, clean it up immediately using absorbents or other acceptable methods.
pH – pH is a measure of the acidity or alkalinity in water. A pH of 7 is neutral. The acceptable pH range in storm water is from 6 to 9. pH values less than 6 indicate that storm water was exposed to an acidic substance such as lead-acid batteries. pH values greater than 9 indicate that storm water was exposed to a basic substance such as cement and some types of cleaning products. Much like the other parameters discussed, the pH of storm water affects the water quality of the body of water that receives the storm water flow. The acceptable range for storm water flow (6 to 9) is the range at which most aquatic organisms can survive. Any values above or below these numbers can cause detrimental impacts to animals living in the lakes, streams, etc. Good housekeeping is the best way to prevent high or low pH values. Don’t let rain contact batteries, cleaners or other potentially harmful materials on your yard.
Carbonaceous Biochemical Oxygen Demand (CBOD) and Chemical Oxygen Demand (COD) – These sample parameters represent the oil, grease and other materials present in the storm water. As the contaminants decompose in water, dissolved oxygen is used in the breakdown process. Neither CBOD or COD points to a specific storm water contaminant, but rather the presence of one or more contaminants that during degradation have the potential to deplete dissolved oxygen. If large quantities of contaminants are present, the available oxygen in surface water bodies (lakes, rivers, streams, etc.) can be depleted to the point that fish and other aquatic life suffocate from lack of oxygen.
Metals (Aluminum, Copper, Iron and Lead) – Aluminum, copper, iron and lead are the four “salvage yard metals” that the Indiana Department of Environmental Management (IDEM) requires in storm water monitoring. These metals are all common in auto salvage and scrap yards. Grinding metallic parts and crushing can generate small metal particles that are easily mobilized by storm water and transported along with sediment to receiving waters. Large concentrations of metals in water are toxic. Metals uptake in aquatic plants and animals and are stored in body/plant tissues. Large concentrations of metals in fish are toxic to humans and other organisms that depend of fish for a food source. Yards that conduct extensive grinding, cutting or shredding have the most problematic metals concentrations based on our experience. The more of this activity you can conduct away from storm water the better.
Nitrogen, Total Kjeldahl Nitrogen (TKN) and Phosphorus – These three parameters all represent the presence of nutrients in storm water. Nitrogen and phosphorus are essential nutrients that encourage plant growth. Both are key components to fertilizers. Sanitary sewage, animal waste and vehicle exhaust are also contributors to contamination in the environment. These parameters encourage growth of plants used for food crops but also provide necessary nutrients for water plants once deposited in a lake or pond. Large amounts of nitrogen and phosphorus in lakes and ponds causes algae to bloom at increased rates and depletes dissolved oxygen killing fish and other aquatic organisms. Algal blooms block sunlight from penetrating the surface of the water preventing growth of other crucial water plants.
This is only a brief description of each of the required storm water parameters. I could probably write a whole article about each. But in general terms, if you monitor your storm water outfall(s) and a problematic result is present, it is crucial to determine what areas of your operation might have caused the elevated result. By understanding where each of the contaminants originates, it is much easier to determine the source of the problem and fix it. If you have high oil and grease, you need to tighten up your storage/handling practices or do a better job draining vehicles. If you have high TSS, you need to address the areas that are the most muddy and/or dusty – prevent erosion/transport of sediment and debris. We are more than happy to help you figure out what areas you could improve to reduce concentrations of harmful constituents in your storm water. Give us a call. See you all at the CMAR Convention in September!
This article was originally featured in the August/September 2012 issue of ARI Magazine.