tanks and bird droppings contribute to the stew of pollutants that pour
into the ocean during and after storms on the Outer Banks, but measures
to remediate the toxic flow could prove to be costly and politically
draft report on a stormwater pilot project almost a decade in the
making details episodic elevated levels of bacteria from fecal
contamination at Nags Head and Kill Devil Hills beaches in the vicinity
of nine ocean outfalls – large pipes maintained by the state Department
… results from monitoring of outfalls from this study, conducted over a
wide range of storm events, clearly indicate that Enterococcus sp.
levels along beaches impacted by outfall discharge consistently exceed
water quality standards throughout and well after a storm event,” the
document said. “Furthermore, the impact of the Enterococcus sp.
contamination appears to extend to distances in exceedance of 100
meters up and down the beach from outfall pipes.”
N.C. Department of Environmental Quality, or DEQ, paid for report,
called the “Ocean Outfall Master Plan.” Done in conjunction with the
Coastal Studies Institute in Wanchese and the UNC Institute of Marine
Sciences in Morehead City, the report is currently undergoing review.
The Raleigh-based engineering firm Moffatt & Nichol submitted a
draft to DEQ, which sent it back with comments. Others involved with
the project have also submitted comments.
& Nichol will incorporate those comments into the report, which
will then be the subject of meetings along the Outer Banks. The final
report is expected within a month or two, said Johnny Martin, coastal
and hydraulic engineer at the engineering company.
is, he noted, the first large-scale study of its kind in the state,
although the large majority of state-maintained ocean outfalls are in
the final report is submitted, we’ll review it thoroughly and determine
next steps,” said Tom Reeder, an assistant secretary at DEQ.
runoff on the Outer Banks can contain high levels of bacteria from
human and animal waste, but it also can carry pollutants from
fertilizer, pesticides and petroleum products like oil and gas.
Although sewage treatment systems are few on the Outer Banks, their
discharges are not released through pipes going to ocean beaches.
state has been sampling swimming waters at ocean and sound beaches
since 1997, said J.D. Potts, manager of the Recreational Water Quality
Program at the state Division of Marine Fisheries. About 10 years ago,
permanent signs warning swimmers against possible pollution were posted
at all the ocean outfalls on the Outer Banks.
said that bacterial contamination is generally highest after rainfall.
But since it’s harder to detect when water is flowing from the mostly
submerged pipes on the Outer Banks, he said, the agency decided it was
safer to have a permanent posting at the drainage pipes warning
swimmers to stay 200 feet away.
“We’re hoping people pay attention to the signs,” he said, “because we recognize at times there is a risk.”
said the recreational waters are tested every Monday or Tuesday between
April 1 and Oct. 1 at 240 sites throughout the state for excessive
levels of enterococci, an indicator bacteria for pathogens found in the
intestines of warm-blooded animals. When unsafe levels are found in
samples, a swimming advisory will be issued and a sign will be posted
until the levels fall. The bacteria increase the risk of
diarrhea, vomiting and skin infections.
year, there has been only one ocean swimming advisory issued briefly in
Dare County, Potts said. The location, 100 feet north of
Jennette’s Pier, was likely affected by pier fishing, not storm
drainage, he said.
state testing is not done directly from ditches where stormwater
collects from the watersheds, Potts said. Samples are taken about 10
feet from the outfalls. Bacteria levels, he said, would be higher in
data indicate that while beach closings are a result of sampling
conducted at the outfalls, there are water quality issues throughout
the town’s watersheds,” the report said. “These must be considered when
selecting the appropriate measures to improve beach water quality.”
of the issue with bacteria in stormwater, according to the report, can
be blamed not only on animal waste, but on the thousands of septic
tanks that have been permitted in this resort community, at least some
of which may be in poor condition or in locations with high water
Flythe, Dare County’s environmental health supervisor, said about 45 to
60 septic permits are issued each month, based on conditions, among
others, that require certain distances from other properties and the
mean high water mark. Inspections take place before the permit is
issued and after repairs. But otherwise, he said, it is up to the
property owner to monitor the condition of the system.
report lauded the town of Nags Head for the septic-tank initiative it
launched in recent years that involves voluntary citizen participation
in inspection and maintenance of septic tanks in town. So far,
Kill Devil Hills has not adopted a similar program. But town manager
Debora Diaz said she has made the board of commissioners aware of the
the final document is presented, the board will review and consider the
recommendations for Kill Devil Hills,” Diaz wrote in an e-mail. “The
board is interested in learning more about the Septic Health Initiative
program that Nags Head began a number of years ago.”
Head officials are also closely following the development of the
report, noted Cliff Ogburn, the town manager. “The Town has always been
interested in water quality and it continues to pay close attention to
information that will help us develop policies and programs to protect
the environment,” he wrote in an e-mail.
hope to leverage this information along with the other resources
available to us, including the water quality monitoring data from the
Town’s Septic Health program, to see what actions we might consider
moving forward to continue to facilitate the proper functioning of
septic systems and
mitigate any potential impacts to groundwater and surface water
quality. This remains one of our most important goals as a
community. We will address the challenges of managing this
environment as best we can.”
is clear that, in general, leaking septic tanks contribute loads of
bacteria to stormwater, especially when it rains. “At mean
groundwater table levels, the portions of the study area where
groundwater is in the range of 0-3 feet below the surface are largely
concentrated in more developed areas, which is problematic because that
is where the highest concentrations of on-site septic systems are
located,” the report stated.
times of high groundwater levels, groundwater passes up through the
septic layer and can be seen at or above ground level as standing water
throughout significant portions of the study area.
only does this pose a health concern, but it also is an indication of a
need for stormwater drainage,” the report continued. “This upward
movement through the ‘septic layer’ and out to the surface may be an
important dynamic in the high concentrations of fecal indicator
bacteria in stormwater runoff events.”
That human waste is contributing to the problem was confirmed by tests done at the Institute of Marine Science.
blessing is that bacterial contamination of beaches is typically
short-lived, thanks mostly to ocean currents and the volume of water in
the ocean that dilutes the concentration. But standing water – the
impetus for the stormwater study in the first place – is another story.
goes way back to Sen. (Marc) Basnight in 2007, when we had a series of
rainfall events,” recalled Nancy White, director of the Coastal Studies
Institute in Wanchese. “People just went crazy and they inundated his
office with telephone calls.”
Basnight, a native of Manteo, was at the time the leader of the state Senate.
parking lots and roads, especially on the northern Outer Banks, had
been flooded by rain, and the increasingly wretched water not only
didn’t drain away, it worsened with each storm. For weeks, people had
to navigate through huge pond-sized puddles in their neighborhoods or
try to pass through fetid rivers of floodwater on roadways.
was determined that the only entity with responsibility for stormwater
management in the county was NCDOT, which was responsible for
maintenance of drainage outfalls.
it was agreed that it was necessary to find out the volume and
bacterial load of the runoff going through the outfalls.
CSI was actively involved in collecting data for the study and was
supposed to analyze the results to determine ways to remediate the
stormwater and its pathogen content. For two years starting in 2007,
stormwater in outfalls was tested by the coastal scientists.
are 900,000 to 1 million gallons flowing through each pipe for every
inch or two of rainfall,” White was quoted in a 2009 article in The
Virginian Pilot. “There’s tens of thousands of cells of bacteria in
every liter of water. The hard part is figuring out where the bacteria
is coming from.”
when about $12 million of the original $15 million appropriated for the
stormwater project was diverted to cover construction costs for
Jennette’s Pier, the role of CSI was diminished, White said, including
work on the study. “I’m not directly involved,” she said this
part of the state effort to reduce the stormwater bacteria, a pilot
study of a “best management practice” was launched at the Conch Street
outfall in Nags Head that involved installation of a filter system
known as the AbTech Smart Sponge. Designed to capture the majority of
the bacteria before the water reached the ocean, the system was
enclosed within a concrete vault under the parking lot and directed
water through two rows of 60 bacteria-attracting filter packs. Total
costs for the device, including construction and a one-time replacement
of filters was $1.3 million, Martin said.
remainder of funds, about $1.7 million, was split between CSI, Moffit
& Nichol and IMS for the outfall report, data collection and
the sponge technology, used successfully in Rhode Island, proved to be
ineffective on the Outer Banks, partly because the water flows were
much higher. “Higher tides impeded flows to be efficiently transmitted
through the device,” Martin explained. “When tides were low, measurable
treatment was achieved.”
to the report, the filters were repeatedly clogged by sediment and at
times ended up increasing the levels of bacteria discharging from the
pipe compared with water going into the pipe. Possible remedies
suggested in the report included use of better – and less expensive –
filters and installing a pumping system to better control groundwater
of the watersheds feeding into the outfalls in both towns were analyzed
– size, drainage, permeable land, pathogen loading, number of septic
tank repairs – and recommendations were made for managing the
stormwater and controlling contamination from septic tanks and animal
waste. The report offers several possible solutions:
- Detention basins or shallow marsh systems that allow bacteria removal and provide flood control.
- Sand filters at or above ground to treat large drainage areas.
- Infiltration systems for treatment in limited spaces.
- Pumping system to manage groundwater levels.
- Bio-retention areas that can provide high rates of bacteria removal.
- Catch basin inserts like the Smart Sponge filters at Conch Street.
- Alum injection and UV disinfection systems that can remove high levels of bacteria.
- Multi-chamber treatment units for small drainage areas.
- Electrocoagulation treatment systems that are fully automated and remove high levels of bacteria.
- Deepwater ocean outfalls that could expand capacity for future stormwater improvements.
challenges are inherent in each option, whether high cost,
inappropriate use with a high water table, unavailable land, intensive
maintenance requirements or questionable effectiveness.
of the things that makes the Outer Banks so challenging is there’s not
a lot of room between elevation of the beach road and the high tide
levels,” Martin said. “Part of the issue is there is such a high water
matter what method, if any, is chosen to address stormwater and clean
beaches on the Outer Banks, there is a looming issue not dealt with in
the draft report that will only exacerbate the challenge -- rising seas.
sea level does rise, then we would expect that the issue would be more
problematic,” Martin said. “But I think any sort of effect from
sea-level rise is a long way off.”
article is provided by Coastal Review Online, an online news service
covering North Carolina's coast. For more news, features, and
information about the coast, go to www.coastalreview.org.)