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Page 12 of 20 <br /> Storm Water Management System Assessment <br /> Orono Truck Station <br /> Table 4—Survey Measurements West Pond <br /> Rod Reading Approximate Elevation <br /> Location:OR-1 <br /> 152665.567,438197.848,838.386 <br /> Top of Sediment from Ice 1.0 NA <br /> Bottom of Sediment from Ice 2.6 NA <br /> Depth of Silt 1.6 ft <br /> Location:OR-2 <br /> 152674.771,438167.812,838.797 <br /> Top of Sediment from Ice 1.0 NA <br /> Bottom of Sediment from Ice 1.8 NA <br /> Depth of Silt 0.8 ft <br /> Note: No benchmark elevation was available <br /> It appears an average of 1.2 feet of sediment has accumulated on the bottom of the basin. No standing <br /> water was observed in the west pond and the sediment deposition could be described as mud or slush like. <br /> Evaluation <br /> The East pond has been in operation for 12 years and during that time appears to have been functioning <br /> properly. However, the maturity and prevalence of cattails in the east pond is an indication that the <br /> permanent water level in the East pond is below 2 feet. The design permanent water level of the east pond <br /> could not be determined from the 2005 technical memorandum or from the survey provided by Hennepin <br /> County Property Services. The 2005 technical memorandum noted no sediment accumulation in the East <br /> pond, and it is assumed no removal of sediment has occurred since the pond's construction in 2002. The <br /> West pond was already in place at the time the East pond was constructed. It is unknown how long the <br /> West pond has been in use. No record of maintenance activity in the West pond was available, and it is <br /> assumed no removal of sediment has occurred in the West pond. <br />