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Stormwater
Discharge Above the Performance Standard - Monday, January 25, 2010
As
required when significant rain events occur, on January 25, 2010, AGC and
SCE personnel conducted an Erosion and Sedimentation Control Inspection at
the Marjol Site. During the inspection, they noticed that the water leaving
the basin had much more sediment in it than normal. In taking the
daily turbidity reading,
(Click
here for Stormwater Sampling and Discharge information), the water was
found to have a sediment load well above the performance standard: 1785 NTUs
when it is supposed to be below 250 NTUs. Upon investigating, they observed
that the skimmer head had separated from the skimmer arm and the arm dropped
below the surface of the basin allowing sediment-laden water from the bottom
of the basin to be discharged through the outlet structure.
An additional turbidity reading was taken at the discharge point (2183 NTUs)
and a series of turbidity readings were collected in the discharge channel,
Sulphur Creek and the Lackawanna River.
At the confluence of Sulphur Creek
and the River: 119NTU, 116NTU
Sulphur Creek below the discharge:
168 NTU, 145 NTU, 112 NTU
Sulphur Creek at the discharge (rip
rap): 1840 NTU, 1918NTU
Lackawanna River below Sulphur
Creek: 132 NTU
Sulphur Creek above the discharge:
93.9 NTU, 90.0 NTU
At the discharge point from the Site
(fence): 2183 NTUs
Water samples (one for total lead and one for dissolved lead) were collected
from the discharge point and were sent to the laboratory for analysis. The
dissolved lead analysis showed a very small amount of lead in the water
(0.094 ug/L). The laboratory sample that is used to determine whether there
is contamination of the instrument or something else in the laboratory also
showed about the same small amount of lead in it, which means that there was
no detectable level of dissolved lead in the discharge water from the site.
The NPDES permit standard for maximum dissolved lead for the Site is 650 ug/L.
The total lead result was 64.4 ug/L. There is not an NPDES standard for total
lead. The very low total and dissolved lead results provide reassurance that
even though the turbidity levels were above the performance standard, there
was NOT a release of lead from the site that would affect the creek or the
river.
It is believed that the freeze/thaw in the basin caused the skimmer head to
separate from the skimmer arm. A site inspection had been performed by AGC
on January 22, 2010 and the skimmer head was attached correctly at that time
and the basin surface was frozen.
SCE repaired the skimmer on January 26, 2010. Dewatering through the skimmer
resumed once the skimmer was repaired. AGC collected the following
turbidity readings to document that the water at the surface of the basin
that was being discharged was below the 250 NTU performance standard:
At discharge pipe – 59.9 NTUs
At discharge point from the Site
(fence) – 65.1 NTUs
In basin: Range from 35.8 to 84.5
NTUs
USEPA and PADEP representatives were on Site on January 25, 2010 and
notified of the situation. Throop Borough was notified on January 25, 2010
and its Compliance Liaison was on Site on January 26, 2010. Lackawanna
County Conservation District was also notified. As is required, a
non-compliance report was submitted to PADEP on February 1, 2010. (Click
here to review the January 25, 2010 Non-Compliance Report.)
(Click here to go back to the
January 2010 stormwater calendar page.)
Page Last Modified
Tuesday October 19, 2010 03:48:15 PM
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