STORMWATER DISCHARGE ABOVE THE PERFORMANCE STANDARD - MARCH 30 and 31, 2010
Over 1.5
inches of rain was received on March 30, 2010. The skimmer had been flipped
to prevent water from leaving the basin. (Click
here for Stormwater Sampling and Discharge information) When SCE and
AGC representatives checked the Site in the evening during the rain event,
there was flow coming from the discharge pipe due to a leak in the skimmer
arm. AGC took a turbidity reading at the discharge point and the result was
77.5 NTUs at 7:30 pm. (Turbidity is a measurement of the cloudiness of the
water which is caused by sediment.) The basin had filled up to the point of
almost going over the baffle, so AGC representatives flipped the skimmer to
allow water to discharge from the basin. Shortly after flipping the
skimmer, AGC checked the turbidity at the discharge point. The turbidity
was 330 NTUs at 8:45 pm. The turbidity level is supposed to be below 250
NTUs for discharge, so AGC flipped the skimmer back into the closed position
to stop water from flowing into the discharge channel. There continued to
be some flow in the channel due to the leak in the skimmer arm.
On March
31, 2010, a turbidity reading was collected at the discharge point at 8:45
am. The turbidity result was 330 NTUs.
A
turbidity reading of 324 NTUs
was
collected at the discharge point at 9:30 am after additional BMPs (hay
bales) were added in the channel outside the fence. Turbidity at the
confluence of the discharge channel and Sulphur Creek was checked as well.
Two turbidity readings were taken at this location: one was 152 NTUs and the
other was 158 NTUs. This demonstrated that while compliance with the
performance standard was not achieved at the discharge point, it was met
before the water entered Sulphur Creek. As requested by AGC, SCE plugged
the skimmer orifice inside the outlet structure around the skimmer orifice
plate. Once the plug was in place, flow into the discharge channel was
reduced by approximately 90%. AGC observed that by approximately 1 pm, all
flow in the discharge channel had stopped.
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 result was 4.4 ug/L. The NPDES permit standard for
maximum dissolved lead for the Site is 650 ug/L. The total lead result
was 33.9 ug/L. There is not an NPDES standard for total lead, but the
total lead result will be compared to the turbidity levels and then to
the dissolved lead result. 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.
The
skimmer and orifice were repaired during the week of April 5, 2010, to
prevent further leaks into the structure.
EPA,
DEP, and Throop Borough were notified of the turbid discharge. As is
required, a non-compliance report was submitted to PADEP on April 6, 2010.
(Click
here to review the Non-Compliance Report.)
