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Gty of Centerville Page 3 <br />Downtown Storm Water Redamabon Project 6/8/10 <br />The pH of the water is a bit out of the desirable range for turf grass growth. There are, however <br />prescribed nutrient levels for fertilizers which can help mitigate this higher -than -desired pH. <br />Increasing the amount of iron and manganese can allow the higher pH level to be viable. It <br />should also be noted, that the current pH of the soil is in this same range and has been <br />supporting turf grass growth thus far. <br />Pond Sediment <br />One sample of the sediment was taken from the Anoka County Park pond (the one to be used for <br />irrigation). The sample was taken at a location near the middle of the pond. <br />The pond sediment was tested for two different reasons. Firstly, we wanted to know the <br />constituents of the sediment since the City has agreed to take over maintenance of the pond in <br />exchange for its use, and the make-up of the sediment can drastically affect the cost of dredging. <br />If the sediment is polluted enough, the material must be landfilled, at great expense. Even <br />though the irrigation system will be designed to ensure sediment is not lifted off the bottom, <br />there could be a public perception that if the sediment is contaminated to the point of needing to <br />be landfilled, the water must be too. <br />The standards shown below are those which elevate the sediment to the point of needing to be <br />landfilled. In brief the standards and our results are: <br />Pollutant Result (Sample 1) <br />Human Health <br />Arsenic 5-20 mg/kg Average 6.0 mg/kg <br />Copper 50 mg/kg Average 7.3 mg/kg <br />Mercury 0.020 - 0.625 mg/kg Avg. ND ng/kg <br />Pond Dredging Level 1 Threshold Level 2 Threshold <br />Arsenic 9 mg/kg 20 mg/kg 6.0 mg/kg <br />Copper 100 mg/kg 9000 mg/kg 7.3 mg/kg <br />Mercury ND mg/kg <br />pH N/A <br />Chloride N/A <br />CPAH's <br />Fiuoranthene 1080 mg/kg <br />Perylene N/A <br />N/A 8.4 Standard Units <br />N/A ND mg/kg <br />6800 mg/kg ND ug/kg <br />N/A 42.6 ug/kg <br />Conclusions — Pond Sediment <br />For human health concerns, the levels of heavy metals in the pond sediment are within <br />established ranges of those which occur naturally in soil or are tolerable without risk to human <br />health. <br />Comparing the results from our tests to the thresholds needed for pond sediments to require <br />special handling, you'll see that they are under the established limits. <br />106 <br />