In July of 2005 an angler reported a fish kill on the river Tolka at Clonee to the ERFB
The ERFB sent out fisheries environmental officers.
On site inspection reviled a discharge pipe leading from a abattoir close by.
The area around this pipe was chemically burned and the water was discolored
The area was absent of flora and fauna downstream from this point.
This was a point source pollution event. (1)
Upstream approx 5M there was small fish alive but were absent downstream
They proceeded to take samples of water in a standard method
During this process it was noticed that a smell of noxious gases was increasing
A shortness of breath and a skin /eye irrigation by the officers ...view middle of the document...
Photos of the area
This photo shows where the pipe in red which was collecting surface water only to the river was contaminated by a leakage of effluent, normal conditions allowed the waste to flow from WWTP by the blue outlet. BOTH PIPES NOW ENTER THE NEW SEWAGE SYSTEM SUPPLY.
This photo shows where the water is taken from the river and returned via WWTP after factory use.
The samples would have been fixed on site and further anyalis by labrotory was needed
As viewed above the river had normal conditions before the pollution entered the river. From the pipe the neat discharge mixed with the river and an instance reaction occurred removing oxygen from the river. However within 120 m the amount had reduced by 7 fold. The samples only provide information for this area.
BOD (5) AND THE DEAD ZONE
This is the amount of oxygen depletion in the river caused by the pollutant. The chemical NH4 entered the river and mixed with H2O and formed NH3 and H3O.
However the H3O wants to become H2O and return to normal but this reaction removes oxygen (o2) from the water in the area as there is too much hydrogen present. It took 7km for all the H30 to be converted back and return to normal conditions. With the loss of such high levels o2 it caused this fish kill and other bio life’s to die. –
Fresh water guidelines
– >0.1mg/l indicates sewage
– EU surface water regs 0.2-4mg/l
– Freshwater fish regs <0.005-0.2mg/l
– Drinking water <0.5mg/l
– Surface water regs <50mg/l
– Drinking water regs <50mg/l
– Surface water regs <5-7mg/l O2
– Freshwater fish regs <3-6mg/l O2
– Salmonoid Water regs <5mg/l O2
The chemical oxygen demand above shows normal conditions and as in the BOD the river diluted the chemical 10 fold this time. The reaction with water and the chemical helped deal with this spillage.
Ph rose as expected but fast flow mixture shows reduction . mixing helps reduce levels
This chart shows the solids in the water samples .Normal conditions and the discharge from the pipe, However the chemical caused a larger release of solids into the river at any fast flow area. Dead matter and debris would account for this.
This chart shows the amount of Phosphate let into the water. The amount in the pipe was only just above the limits allowed 0.1- 2.0 mg/L. The river dealt with this very quickly and levels were back to normal quickly. The levels of phosphate in the river before the pollutant would indicate small amounts of phosphate in river. This was...