South Bethany considers aeration to improve canals
South Bethany has dredged its canals to improve navigability, briefly added water jets to try to improve water flow and considered a multi-million-dollar tidal pump project that would flush the stagnant waters to the sea, but the latest idea to improve water quality in the canals is literally full of air.
At an Aug. 27 town council workshop, resident George Junkin, who serves on the town’s Canal Water Quality Committee, and Councilman Jay Headman offered a presentation on the water quality situation in the canals, including an overview of what’s being done now and has been done in the past about the problem and what the committee is recommending the town consider in the future.
That future could include pumping air into the canals with an air diffuser system that would help oxygenate the often oxygen-deprived water and improve its flow. If the council follows the committee’s recommendation, the idea could kick off with a pilot project in two of the town’s most stagnant canals: the Petherton and Anchorage canals.
The air diffuser system – recommended to the committee by Todd Fritchman of Envirotech, who provided a ballpark estimate for its cost to the town at no charge – would, Junkin said, be “like turning the canals into an aquarium, with bubblers.”
Junkin said the visible result would be that one could see a disturbance on the surface of the canals but it would not hurt boat traffic – unlike the some implementations of the water-jet system that the town tested in the past.
To deploy the aeration system in the 1,600 feet of the Anchorage and Petherton canals would cost roughly $15,000 per canal, using a compressor that could be plugged in at utility poles on Route 1. The compressors would be no larger than a small trash can. The diffusers – about six along the length of aeration tubing in each canal – would stick up less than a foot from the bottom of the canal.
Unlike the former water-jet system, the aeration system would require no electrical system in the water itself.
Junkin said aeration systems had been shown to mix the water well and to reduce some nutrients that promote the growth of algae. The systems could oxygenate the entire canal and improve its health, mixing the water in the upper 4 to 8 feet of the canal, while allowing aerobic bacteria to decompose the muck that accumulates on the bottom of the canal.
The systems would cost the town about $750 per canal to operate for five months, which Junkin said would be the recommended operation period, as the canals suffer the worst conditions during the hot summer months and the town is operating under fiscal constraints.
“We’re not here to ask for money,” emphasized Headman. “We’re looking for possible solutions.” He said the town could write a grant proposal looking for money for the pilot program. “The town owns the canal. We can’t do anything unless the town approves,” he added.
Junkin said the committee might look for matching grants from state agencies.
Councilman Robert Youngs asked Junkin whether the aeration systems have been proven to help with water quality issues, and how effective they might be compared to the proposed tidal pump, which is considered yet-unproven technology with a big price tag attached.
Junkin said the aeration systems have been shown to work, particularly in freshwater canals and in stormwater ponds.
“The only difference is our canals are salt water instead of the fresh water in most ponds,” he said, noting that difference was the reason the committee was recommending a pilot program – to see if the systems would hold up and work well in the canals’ brackish water.
Junkin said he believes the town should consider its canals as basically the same as stormwater ponds, so stagnant in their flow to and from the Little Assawoman Bay that they require aeration to be healthy.
Mayor Gary Jayne noted the difference from the deployment of existing aeration systems in the region, though: the town’s canals are open-ended, feeding into and out of the bay. And, he emphasized, the prior water-jet system “didn’t work so well. It just stirred it up.”
“We’re not saying we should do this in all our canals,” emphasized Junkin, “but we should do a test, as we did with the water jets. We’re trying to get expert opinions on whether it would work in the saltwater canals. The opinions so far say it should work, but money is scarce for funding to try it.”
“The opinions are it’s worth trying, but we’re not there yet,” added Headman.
Studies, programs aim to improve quality
The goal of South Bethany’s Canal Water Quality Committee, which was established in 2007, is to make the canals fishable and swimmable, to educate the community on the water-quality issues, to work with state and local government on the issue, to review ordinances and create new ones to eliminate pollutants and to work with the Center for the Inland Bays.
Junkin said the problems the canals are experiencing are ones caused by population explosions. In the last half-century, the area has gone almost no impervious surface coverage to nearly 50 percent impervious surface coverage.
He said problems with water quality in the canals had started to be noticed around 1970, and a 1996 study had shown that the level of fecal coliforms and pollutants measured in assessing water safety for swimming at that time in the Anchorage and Petherton canals were as high as 20 times the acceptable standard.
With so much impervious surface, the Anchorage canal serves as a major dumping ground for much of the stormwater generated along Route 1 from central South Bethany to several blocks into Bethany Beach town limits – about 65 acres worth of stormwater, collected from the Sea Colony area and to the west, including Sea Colony West.
A 2004 study of the Anchorage canal’s forebay, Junkin said, shows that the system “does as well as can be expected, but there’s so much water going into it that that bay’s not big enough to do the job they want it to do.” The canal’s catch basins don’t actually filter the water, either. They just hold it and feed it into the canals.
The forebay is considered only 28 percent efficient. “It collects sediment but not much else,” Junkin said. The town recently dredged the canal to improve boating access, but even clearing it of silt did not improve the water quality.
Headman also pointed out that stormwater that drains on the west side of Route 1 goes straight into the canals, most all of it untreated.
The town has been participating in a water-quality program with the CIB. Headman noted that the program’s studies had always indicated the poorest quality in the Anchorage and Petherton canals, which are far removed from Snap Gut, where the bay water enters and exits the canal system.
Particular concerns focus on dissolved oxygen (DO) levels. From May through October, they’re below 4 ppm - too low for most marine life to survive. For example, hard clams can survive at 4 ppm, blue crabs until 3 ppm, spot at even 2 ppm, but perch require 6 ppm. Higher temperatures reduce DO levels, meaning there’s always less DO during the summer, resulting in the fish kills seen in canals throughout the Inland Bays watershed each summer.
Algae also grows better in summer, supported by nitrogen/phosphorous that flows into the canals and bays, and that further reduces DO – particularly between midnight to 8 a.m., when algae exhales carbon dioxide rather than producing oxygen.
With continuous DO monitoring locations now established in the canals, Junkin pointed out that the Petherton canal had the worst quality in 2008, while the Snap Gut area was the only one where bacteria levels weren’t too high. The canals were essentially stagnant elsewhere.
One active part of the canal water-quality program is the area’s oyster gardening program, with the CIB helping to oversee some 110 floats of baby oysters maintained by owners of water-front property, including the canals. It has proven so popular that there’s a waiting list to join the oyster gardening program.
Oysters can provide tremendous benefit in filtering water, but even the popular program isn’t considered a cure-all. “It won’t cure the problems, but it is being used elsewhere,” said Junkin. “It demonstrates that oysters can grow in this kind of environment, and they do filter the water.”
Canals essentially stagnant
Still, the South Bethany canals are need of a freshening up that no amount of oyster spat can provide.
The 2005 canal flushing study for the proposed tidal pump project showed the “residence times” of the water – how long it stays in the canals – was in some cases above 120 days, including at the east ends of the town’s easternmost dead-end canals. Other canals nearer to Snap Gut held the same water for just a few days.
“Essentially, there is no flushing,” said Junkin. “They’re acting like stormwater management ponds with no aeration like stormwater ponds are supposed to have.”
The proposed tidal pump project – at a cost of $5 million initially and about $20,000 per year to operate – could flush all the water in the town’s canals in a couple days. It would call for two large pipes feeding into the ocean from a series of feeder pipes leading into each of the town’s canals, through which the canal water would flow into the ocean and the ocean water into the canals. But the costs alone have kept the idea in the planning stages.
“DNREC made it clear they were not in a position where they would support us,” said Junkin.
The water-jet aerators tested from 2000 to 2002 were deemed a failure. Since they couldn’t spray up in the air lest they disturb boat traffic, they were deployed horizontally, which allowed them to increase the DO at the bottom of the canals but kept the average DO levels of the water the same. They also had a high cost to operate.
The town is getting some help with the water quality issue from state and federal officials, most recently demonstrated as the Anchorage Canal Stormwater Drainage Assessment Project got under way last month.
With a $35,000 grant from the U.S. Army Corps of engineers and assistance from DelDOT engineers and the CIB, the group is on the sixth task of a 10-task assessment of the problems.
The next element of the assessment is the drafting of a strategy, with the target for a final paper in December. The overall goal is to capture the pollutants in the stormwater “before it gets some place.” The elements involve include reducing pollutants before they enter the canals, as well as retrofit strategies and education.
South Bethany takes the lead
Jayne emphasized on Aug. 27 that while South Bethany’s problems with canal water quality have been much talked-about, “The situation with water quality in our town is no different than in any other town, no worse than Fenwick, for instance, or Bethany Beach.
“Dewey has no canals, but the stormwater goes into the Inland Bays, washing down the roads and through catch basins. When there’s a heavy rain, you can stand on the beach in Dewey and see a big circle out there.”
The lack of stormwater systems when the area’s geography was altered by the dualization of Route 1 has shaped the issue beyond a quick fix.
“We’re in the middle of stormwater on one side and the bay on the other side, and we’re in the middle, trying to do the best we can when we’ve got these two influences we can’t do anything about,” Jayne said.
“If we were to do anything and everything we can do in town here, we’d still have the bay and the stormwater. But we have got to do what we can, what is feasible, because it’s the right thing to do.”