|
| |
|
Stormwater Sampling and Discharge System –
During Construction (May 2008 to August 27, 2010)
During
construction activities, there was the concern about the possibility of lead
attached to soil particles being washed into the sedimentation basin and
discharged from the Site. Several precautions were taken to monitor for
this and prevent the release of lead from happening:
-
BMPs Installed – BMPs (best management practices) such as silt
socks, silt fence, and a sedimentation basin with baffle and skimmer
were installed to minimize the release of soil particles from the Site.
-
Turbidity readings Collected at Discharge Point - The water
discharged from the basin was sampled using a turbidity meter.
(Turbidity is the amount of soil particles in the water.) The turbidity
standard in the 100% Design Plan is 250 NTUs. The turbidity standard
for discharge from the Marjol Battery Site was put in place at the
request of Throop Borough as a real-time measurement that could be used
during construction activities to determine if immediate action needed
to be taken versus waiting for analytical results. Since lead sticks to
soil particles, if there was low turbidity in the discharge water, then
there would be, at most, a minimal amount of lead in the water being
discharged.
(Click
here for an explanation of the Turbidity Standard.)
-
Collect lab data on stormwater – Samples of the discharge water are
taken at least monthly and during turbid discharge events and were
analyzed for total and dissolved lead to confirm that discharge from the
Site did not have elevated lead levels.
(Click here for a
picture of water discharging from the basin at the discharge point along
the perimeter fence.)
The 100% Design Plan called for stormwater from the clean areas of
the Site to be collected in the sedimentation basin. Sediment that
was carried along with the stormwater would settle out in the basin,
and stormwater collected in the basin would be released to Sulphur
Creek under a permit issued by the State of Pennsylvania. During
construction of the Final Remedy at the Site, the drainage system
was designed so stormwater falling on contaminated areas of the Site
did not flow into the basin, but was retained within the
contaminated areas by berms.
If there
was not enough space for all of the water to be held within the contaminated
areas, however, the design provided for the potentially contaminated water
to also drain to the sediment basin. Since lead sticks to the sediment, as
long as the sediment was kept on the site by allowing it to settle out of
the water in the basin, the water could be safely discharged to the river.
This sediment could then be excavated and placed into the Containment Area
before the final cap was installed. Removal of sediment from the
sedimentation basin occurred in April 2010. In this way, the water was
managed so that the lead remained on the site by controlling where the
sediment went. But several times turbid water was discharged from the
basin. Since overflow from the CA went into the basin, and water from the
basin went into Sulphur Creek, it was possible for lead from the Site to end
up in Sulphur Creek. That’s why it was important to analyze water samples
for dissolved lead whenever the turbidity standard was exceeded in water
leaving the site during construction activities. This was done, and the
results showed 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.
(Click here to go back to the
Stormwater Management System page.)
|
| |
Page Last Modified
Wednesday January 12, 2011 02:12:02 PM
|
