Laserfiche WebLink
Create sump catch basins at each inlet to the pond which drain to the pond. <br /> Excavate the existing pond to native material. <br /> Fill the pond with granular material to elevation 906.0 (elevation of the existing water in the110 <br /> pond) <br /> Connect sump manholes to surge and rate control manhole next to highway ditch <br /> This eliminates standing water. However, it does not eliminate the detention function of the area; <br /> therefore, the existing"hole"would remain. A sump inlet would be provided at the current <br /> discharge point of the two storm sewer system to remove larger sediment particles. This option <br /> allows the pond to be filled an additional 1.5 to 2 feet. This puts the bottom of the pond around <br /> elevation 906.0 which is near existing normal water elevations. The surcharge manhole would <br /> control the water that gets into the highway drainage system. If water cannot flow through the <br /> small 6-inch orifice opening,it would surge out of the manhole and into the detention area. For the <br /> most part the water quality function of the pond would be lost. However, with proper maintenance <br /> of the sump catch basins, an additional water quality pond should not be required. <br /> Project Cost. $27,000 <br /> Benefits: <br /> Cheap option <br /> Easy to construct <br /> Pond Bottom is near existing normal water elevation. <br /> Non-Benefits <br /> Higher maintenance since sump manholes would need to be cleaned annually. <br /> Does not get rid of the existing hole for the pond. <br /> Will have short term ponding during rainfall events. • <br /> Option 3. New Pipes -No Surge Manhole <br /> Remove existing storm sewer and raise the storm sewer which eliminates the need for sump <br /> manholes. <br /> Excavate the existing pond to native material. <br /> Fill the pond with granular material to elevation 904.6(elevation of the outlet in the highway <br /> ditch) <br /> Connect a 12-CMP standpipe to the highway storm sewer to discharge the pond into the <br /> existing system. <br /> This eliminates standing water by raising the storm sewers so the discharge elevation is above the <br /> invert of the outlet pipe in the highway ditch(904.58). However,it does not eliminate the detention <br /> function of the area; therefore, the existing"hole" would remain. The detention pond would be <br /> modified to treat the runoff by use of a CMP standpipe which should compensate for lost water <br /> quality treatment of the site. The pond bottom would be set at elevation 904.6 which is the invert <br /> of the outlet pipe in the highway ditch. Only difference between this option and option 1 is the <br /> maintenance of the sump inlets is eliminated. <br /> Project Cost. $88,500 47q } 4 01) : 1 1 <br /> Benefit(s): <br /> No annual sump maintenance <br /> 1111 <br /> 3 <br />