Many suburban neighborhoods have retention ponds to manage stormwater runoff volume and mitigate any potential pollution from this runoff.
Over time, these ponds can fill with sediment and other debris, thereby reducing their capacity and effectiveness.
Another unwanted problem is that these increasingly shallower ponds can become inundated with algal growth during the summer.
Few options, however, are available to restore retention ponds to their original depth and capacity.
One commonly used method is to drain the pond before digging out the accumulated material.
This, unfortunately, is a messy and time-consuming process, and it often requires restoring the landscaping around the pond.
In addition, many ponds aren't easily accessible by heavy equipment and the volume of material to be disposed of can be excessive.
Another more environmentally friendly method is to use divers and suction pumps to remove and transfer the sediment to a geotextile (permeable fabric) container where it can dry. Over time, the sediment will dewater, thus reducing the volume of material. When dry, the sediment can either be hauled away, or even better, it can be used as landscaping material or simply graded and reseeded with grass.
This sediment removal/dewatering method was employed by the Hilliard Public Service Department this past summer and fall at the Carrington ponds adjacent to Britton Parkway.
Sediment first was removed from the north pond this past summer and left in geotextile containers to dewater, thereby reducing the amount of material to be managed and maintaining the aesthetic value of the pond while avoiding the cost of landscaping. When dry, the geotextile containers were opened and the remaining sediment solids were excavated and loaded into trucks for transport to an approved disposal/recycling facility.
Based on the success of the north pond, approximately 50 percent of the sediment was removed from the larger south pond this past month and the geotextile bags currently are dewatering. The containers should be removed in the next few weeks, and the remaining pond sediment will be removed in the spring followed by site restoration and seeding.
Thus, this project is another example that Hilliard is working hard to become a model community for sustainable practices.
Greg Smith is a senior research scientist at Great Lakes Environmental Center in Columbus and a member of the Hilliard Environmental Sustainability Commission.