River Watershed “The most effective and efficient method is the TRASHCAT™ marine trash skimmer”
June 18, 1999
Conowingo Hydroelectric Facility
Darlington, MD, USA
Paul Swartz, Susquehanna River Basin Commission (SRBC), opened the meeting, jointly sponsored by the SRBC, Maryland State Department of the Environment (MDE), and Federal Energy Regulatory Commission (FERC). The significance of the meeting was that it represented the first organized public airing of the issue of floating debris.
Debris flow is flood-related and interstate in nature, said Swartz, noting that the Susquehanna River Basin is one of the most flood-prone basins in the country.
Arthur Ray, MDE, indicated that Maryland considers debris to be an issue of serious concern and recognizes the importance of the issue to Bay users and residents.
- The basin is 67% wooded, which covers about 11.5 million acres of land. Wooded land is the main contributor to the debris that enters the watershed. The basin has a high drainage density of 27,500 square miles and nearly 40,000 miles of streams.
- Debris starts to flow when flow at Safe Harbor reaches 200,000 cfs. Debris movement in streams occurs when storms come, water rises and lifts debris off the banks. The flow goes from 1ft/sec, normal, to 6-10 ft/sec during floods.
- With regard to time transport at flood levels, it is estimated that water moves 100 miles per day. It would take a piece of debris 3 or 4 days to travel from the headwaters to the Bay during a high flow. Debris is scoured from the floodplains during high flows.
- Where is debris removed? The first place is at the flood control dams and the second is at the lower river hydro dams, York Haven, Safe Harbor, Conowingo, and Holtwood.
Panel Discussion: Impacts of Debris
Marshall Kaiser, Safe Harbor Water Power Corporation, noted that so far in 1999, they had spent $130,000 and removed 9,000 cubic yards of debris.
He indicated that debris causes problems with municipal infrastructure by clogging bridges and culverts. Approximately $40,000 to $80,000 per municipality is spent each year to remove it. New York pays for debris removal on flood control facilities and on river flats. He said that $20,000 to $40,000 is spent in this manner each year.
Beaches on the Chesapeake Bay in January 1999 were an incredible mess of man-made and natural debris. Users of the Bay, watermen, are constantly faced with damaged boats, logs act as battering rams during storms, Maryland spent $30,000 on removal after fifteen communities asked for assistance.
Panel Discussions: Present Action & Future Potential for Additional Debris Removal at the Dams
Trash Cat working in Safe HarborModerator, Delegate David Rudolph, Maryland State House of Delegates (Cecil County), began the discussion asking the panelists to describe the present efforts underway at their hydro projects to remove debris before it passes downstream.
Bob Sauer, Susquehanna Electric Company, noted that the benefits of the dam are electric generation, recreation, habitat, clean energy source, and the debris management program. Eighty-five to ninety percent of the debris is natural and the rest is man-made. No debris is removed during high flows.
Sauer said their current plan for removal is to collect behind the dam except during spill conditions. Since 1993 they have found the most effective and efficient method is the TRASHCAT™ marine skimmer. It can hold 12-16 cubic yards and then it is unloaded. Man-made debris is then separated from the natural debris. He noted that Conowingo spent $87,000 last year and $120,000 in the spring alone to clean up debris. He also indicated that 3,000 cubic yards has been cleared out so far this year.
He indicated that future plans are to continue the use of the TRASHCAT™ marine skimmer, with sorting at Hopkins Cove, and downstream notification when the crest gates are opened. He said they will support regulatory agencies and keep the skimmer in operation for an extended number of hours.
Orin O’Donel, Safe Harbor Water Power Corporation, provided an overview of Safe Harbor dam operations noting the following:
- No debris is collected during high flows.
- In 1991, a TRASHCAT™ trash skimmer was purchased. It has cost $17,000 to $180,000 per year for the past six years to remove 1,000 to 2,000 cubic yards of debris. Last year after the high flows, 500 tires were pulled from the river that had to be disposed of properly.
- Collected debris is separated on-shore. In 1996, the skimmer wall failed as a result of ice jams and is now being reconstructed with a roadway so a crane/clamshell and dump truck will allow for more efficient removal, but not more material removed. The combination of the skimmer and crane will work together.
Sauder noted that a survey was done, looking at 100 projects owned by 13 utilities. Here were 9 corporate projects, he said, and they went back through five years of methods used and tried to find those most similar to the Susquehanna River Basin. Additional findings included:
- No projects recover debris during times of high flows.
- Most projects sluice debris downstream to maintain aquatic habitat.
- Only 9 projects of 600 required by FERC have debris management plans.
- Others use the UMI TRASHCAT™ trash skimmer too. Those are Duke Power, Appalachia Power, American Electric, New York City, Baltimore City, and Chicago. Most just sluice past dams, but larger projects use UMI marine skimmers.
- There is no available technology that removes debris during high flows.
- Marshall Kaiser indicated that Safe Harbor did a survey as well and came back with similar results.
In response to Moderator Delegate Rudolph’s question about other options the companies could endorse for reducing water-borne debris, Sauer noted that no new technologies seem viable at this point, but they would extend the hours of operation in which the skimmer is in use. – end –
Above comments are excerpted from minutes of meeting published by SRBC Harrisburg, PA, USA