In order to control stormwater at the Site both during construction
and after construction activities have ended, and to keep sediment (small soil particles that are carried along in
water) on the Site and out of the Lackawanna River, a basin and other drainage
features such as check dams and swales were constructed as outlined in the USEPA/PADEP-approved
100% Design Plan for the Site (Click here for more information on the
Final 100% Remedial Design Plan). The stormwater management system consists
of several items as described below.
(Click on the name of the structure to view a picture of the
structure):
1)
Swales -
to direct the flow of water on the Site to the sedimentation basin.
2)
Check Dams
(elevated rows of rocks in the swales) – constructed
to slow the water down as it flows through the swales.
3)
Sedimentation basin –
designed
to discharge water from up to a 100-year storm without overflowing through
the emergency spillway; rainwater that falls on the Site is directed to the
basin. The sedimentation basin is designed to enable sediments to
settle out prior to
the water discharging through the skimmer since water from areas without
established vegetation that drain to the basin may carry sediment. In the
summer of 2012, the sedimentation
basin was converted to a stormwater management basin.
(Click here to read about the basin conversion.)
4)
Baffle
- a fence with fabric on it to slow down the water in the basin after it
comes down from the swales and allow additional sediment settling.
(Removed in summer 2012 as part of basin conversion.)
5)
Skimmer
- when water is released from the basin, it is released through a
skimmer which is a 4-inch plastic tube that skims the water off the top of
the basin and into a discharge pipe. The water then flows out through the
discharge channel and into Sulphur Creek. (Removed in summer 2012
as part of basin conversion.)
6)
Outlet structure –
water from the basin flows through the skimmer and into the outlet structure
which discharges the water into the discharge channel via a pipe to the
opposite side of the basin berm.
The top
of the outlet structure also has an open grate that allows water to
discharge at a much higher rate than the skimmer if it is a heavy enough
rainfall that the skimmer can’t keep up with the water coming into the
basin.
(Click here
to view a picture of water discharging from the outlet structure.)
(Note: In the summer of 2012, the skimmer was removed as part of basin
conversion.)
7)
Emergency Spillway
- a rock reinforced discharge channel for the basin that would carry
flow only if the outlet structure is blocked and can’t discharge water or if
it is more rain that what is expected in a 100-year storm.
