Bacterial Pollution in Poquoson

1
Bacterial Pollution in Poquoson

• Actions to find the sources.
• Tom Meree 12 February 2007

2
High Pollution Areas

• The following chart shows where the highest
  pollution in Poquoson is near population
  densities.
• Data is for a given sampling point averaged over
  1986 to 2006 (21 years). Many readings are much
  higher than the average. The are about 50
  locations measured each month in Poquoson waters.
• The only pollution measured is fecal coliforms
  not nutrients, sentiments or hazardous materials.

3
(No Transcript)
4
Pollution Over Time

• The trend for bacterial pollution has increased
  slightly in Back River and Bennetts Creek and
  stayed about the same in the Poquoson River over
  the last 21 years.
• The installation of City wide sewers has not
  decreased bacterial pollution.
• Levels of concern are 49 for oyster harvesting
  and 400 for beach swimming.
• In 2006, there were 12 samples over 400 in
  Poquoson creeks.

5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
When Pollution Occurs

• The next chart shows pollution levels by the
  orange squares for 2005 and 2006. The red dots
  show days of heavy rain and the three floods of
  2006 are shown. The blue diamonds show the
  amount of sewage pumped from Poquoson each day.
• Higher pollution is usually preceded by a heavy
  rain or flooding. Sometimes there is a heavy rain
  or flooding and there is not high pollution. It
  seems that the source may have been cleaned
  out.
• One can see that usually when there is flooding
  or heavy rain, the sewage flow from Poquoson goes
  up. This is probably due to infiltration into
  the sanitary sewer system.

9
(No Transcript)
10
Consequences of Pollution

• Pollution impairs the health of the Bay and puts
  the public at risk.
• Since the high fecal coliform levels in our
  waters are apparently coming from the land after
  heavy rains or flooding, there may be higher
  concentrations of fecal coliforms on land. If
  true, this is not healthy for people on land
  either.

11
Some Possible Causes of Pollution

• Sewer system overflows / leakage.
• Septic system leaching / flooding.
• Ponds concentrating pollutants.
• Animal waste.
• Boats at marinas.
• Probably a combination of the above varying for
  different rain and flooding conditions.
• Need to test to determine source to be able to
  prioritize cleanup actions!

12
Sewer System

• The sewer system has been observed to overflow
  during extreme flooding (Isabel, Ernesto,
  NorEasters).
• Sewer system has infiltration as shown by
  increased sewage pumping volumes and system
  pressure during heavy rains and flooding.
• Is there leakage out at the higher system
  pressure? There are not consistently high
  pollution levels following periods of high sewage
  pumping, so the sewer system may not be the
  principal cause.
• Leaking sewage water can be seen by either
  putting marker dye in the sewage or by looking
  for washing machine chemicals. The City does
  some testing but more testing is needed.

13
Septic Systems

• In Poquoson, there are 59 or fewer septic systems
  still in known use.
• Septic tanks are supposed to be emptied and
  filled when disconnected. So pollution from
  septic systems should have decreased.
• The City Public Works checks properties for
  proper hookup and leaks when there is another
  reason to check. The City should aggressively
  check for improper sewage discharges.

14
BMP Ponds

• Almost all of the BMP (Best Management Practice)
  ponds in Poquoson are designed for sediment
  capture and water volume retention, not bacterial
  treatment. Do these ponds concentrate and
  nurture fecal coliforms?
• Heavy rains and extreme flooding could then
  easily flush contaminated BMP water into the Bay.
• Also our ditches with stagnant water could
  contribute.
• It would be easy to test by sampling in several
  seasons for fecal coliforms.

15
Animal Waste

• Animal waste is thought by some to be a principal
  contributor. But it is not clear that animal
  waste is present in the quantities needed for the
  high pollution readings we see.
• We can test for this source by a process called
  speciation. Speciation is where individual
  samples are examined to see which species of
  animal the fecal coliform comes from. For our
  purposes, it would be important to know only
  whether the waste is human or animal.

16
Boats At Marinas

• There are two large marinas on Bennetts Creek
  and the sampling point between them has a high
  average fecal coliform reading.
• There have been people living on board their
  boats at both marinas.
• But the fecal coliform sample at this point is
  often below 10. The samples are much higher
  after flooding or heavy rainfall, so the fecal
  coliform pollution from the boats is probably not
  a major contributor to the peak pollution levels
  at this one sampling point.

17
Action

• The City needs to get the Va Dept of Health, Dept
  of Environmental Quality and Hampton Roads
  Sanitation Department fully involved to take
  advantage of their expertise.
• Test BMP ponds and stagnant ditches for fecal
  coliforms and other pollutants.
• After intense rains or floods
• Sample areas around highly polluted areas to
  determine source.
• Do a speciation of a limited number of samples
  to determine whether human or animal waste is the
  primary cause of high pollution readings.
• Continue to search for sewer system leaks and
  improper hookups. Evaluate methods to prevent
  sewer system overflows during flooding
  conditions.