MEMORANDUM Project Specific:

Transcription

1 Information Only MEMORANDUM Project Specific: Policy Memo - File With TO: Robert Flaherty, Bullitt County Deputy Judge Executive FROM: Adam Connelly DATE: RE: 2006 Wet Weather Water Quality Monitoring - Summary Purpose The purpose of this memo is to document the results of the 2006 Wet Weather Water Quality Monitoring efforts. The memo will also include a preliminary analysis and suggestions as to how this effort may be applied in guiding other Phase II Storm Water efforts by Bullitt County in the months and years to come. Figure 1 Wet Weather Monitoring Locations

2 Page 2 Background Strand Associates performed Wet Weather Water Quality Monitoring on one occasion during the primary contact (recreation) season of 2006: October 16, 2005 The wet weather sampling sites were chosen from the approved 22 locations in the original monitoring plan. Due to the increase in cost for wet weather sampling, only four sites were sampled; two on Floyds Fork (FF1 and FF2) and two on Salt River (SR1 and SR2). The laboratory analysis was performed by Microbac Laboratories. Upon receipt of the results, Bullitt County was assured that all data quality expectations were properly met and all samples were analyzed within their respective holding times. It should be noted that one wet-weather sampling event was conducted in 2006 due to an overall lack of appropriately sized. As such, one wet-weather event will be rescheduled to the primary contact season of Sampling Parameters Fecal Coliform a measure of the portion of the coliform group of bacteria which are present in the intestinal tract or the feces of warm-blooded animals (including humans). A fecal coliform concentration of 400cfu/100mL or greater is considered unsafe for human contact. Total Suspended Solids (TSS) a measure of solids (sediment) in the water column that can be trapped by a specific filter. Too much TSS in the water can impact aquatic life in several ways such as by clogging fish gills, making it difficult to breath; smothering fish eggs, insects, and larvae; absorbing more heat from sunlight, which decreases dissolved oxygen; allowing less photosynthesis, and as a result, less oxygen; and so forth. Biochemical Oxygen Demand (BOD) a measure of the quantity of oxygen consumed by microorganisms during the decomposition of organic matter. BOD is typically divided into two parts- carbonaceous oxygen demand and nitrogenous oxygen demand. Carbonaceous biochemical oxygen demand (CBOD), which is what was measured, is the result of the breakdown of organic molecules such a cellulose and sugars into carbon dioxide and water. Generally, the higher the CBOD, the lower the dissolved oxygen. Dissolved Oxygen (DO) a measure of oxygen that is dissolved in the water. DO is essential for aquatic life. Low DO can be attributed to high water temperature because warmer water holds

3 Page 3 less oxygen than cooler water. It can also be attributed to too many nutrients in the stream, because they require oxygen to decompose. Excess nutrients can come from sources such as fertilizer, human and animal feces, and leaves and other organic matter. ph a measure of acidity and alkalinity on a scale on which a value of 7 represents neutrality. Lower numbers indicate increasing acidity and higher numbers increasing alkalinity. The scale is logarithmic, by which each unit of change represents a tenfold change in acidity or alkalinity. Aquatic life is typically impacted by extreme values of ph. Temperature a measure of water heat. Aquatic life native to Kentucky typically has a negative response to extreme temperatures. Results Fecal Coliform Fecal Coliform samples were regularly above the Kentucky instantaneous limit of 400cfu/100ml, which is considered unsafe for human contact. With the exception of three sampling intervals (FF2, 0-1 hr, SR1, 0-1hr, and SR2, 0-1hr) all samples contained fecal coliform concentrations above 400cfu/100 ml. Most of the samples had fecal coliform concentrations ranging from cfu/100ml with the highest concentration being 35,000 cfu/100ml which occurred on SR1 at the 12 hour sample. Such values warrant further investigation into determining the source of such regularly high fecal concentrations. Figure 2 illustrates the sample fecal coliform concentrations. Total Suspended Solids The total suspended solids concentrations at all of the sites were cyclical in nature. Figure 3 shows that nearly all of the samples taken at the first and fourth time intervals had concentrations lower than the expected limit. Typically, the samples taken at the second and third time intervals had concentrations higher than the expected limit, with the highest concentration being 420 mg/l occurring at SR2. Biochemical Oxygen Demand All of the CBOD were less than 10 mg/l. These CBOD concentrations are well below the expected limit of 30 mg/l. Figure 4 illustrates the CBOD concentrations. Dissolved Oxygen Figure 5 illustrates the Dissolved Oxygen concentrations for all of the samples. All of the samples had Dissolved Oxygen concentrations above the expected limit of 4 mg/l.

4 Page 4 ph ph values were always within the KDOW required range of 6 9. for the samples. Figure 6 illustrates the ph values Temperature Measures of stream temperature were always well below the monthly maximum allowable as determined by KDOW. These relatively low stream temperatures may have been influenced by cool air temperatures prior to the sampling event. Figure 7 illustrates these temperatures. Fecal Coliform (Log Scale) Fecal coliform conc (cfu/100ml) Sampling Results (Fecal) Limit (max) Figure 2 Bullitt County Wet Weather Sampling Fecal

5 Page 5 Total Suspended Solids Cabonaceous Biochemical Oxygen Demand TSS (mg/l) Limit Sampling Results (TSS) Figure 3 Bullitt County Wet Weather Sampling TSS CDOD (mg/l) Sampling Results (CBOD) Limit (Max) Figure 4 Bullitt County Wet Weather Sampling CBOD

6 Page Dissolved Oxygen ph DO (mg/l) Dissolved Oxygen Limit (min) Figure 5 Bullitt County Wet Weather Sampling DO PH ph Limit (Max) Limit (Min) Figure 6 Bullitt County Wet Weather Sampling ph

7 Page 7 TEMPERATURE (F) Temperature (of) Temperature Limit (max-oct) Figure 7 Bullitt County Wet Weather Sampling Temperature Conclusions & Recommendations The wet weather sampling data has provided Bullitt County with a baseline of the general quality of its waters. The data may be used in several ways to help guide future Storm Water Phase II efforts. Public outreach efforts may be targeted in specific areas, such as providing fertilizer runoff and buffer zone information to subdivisions upstream and adjacent to streams with low dissolved oxygen. The data will be used as an evaluation tool to compare samples that are taken in Year 5 at selected sites downstream of areas where Best Management Practices (BMPs) were implemented.