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Stormwater Discharges Above the Performance
Standard Post-Construction
(August 27, 2010 to October 16, 2010)
I n
addition to being part of the 100% Design Plan for the Site, the
stormwater management system at the Marjol Battery Site is
maintained and monitored under a permit (NPDES permit) issued by the
State of Pennsylvania (Gould Electronics Inc. and SCE Environmental
are co-permittees on the NPDES permit for the Site.) The 100% Design
Plan called for stormwater discharge monitoring from the Site to be
discontinued at the end of construction because at that point the
potential for lead to be discharged from the Site was removed.
However, the state permit for the Site will remain active until
vegetation is established at the Site., On January 27, 2011, PADEP
clarified its requirements for basin discharge monitoring while
there is limited site activity, BMPs are in place and the permit is
still active. (Click
here to review PADEP’s response letter.)
The
letter stated that stormwater discharge monitoring is not required
on “non-working” (days when there is no earth moving activities).
Note that Gould has elected to continue monthly sampling for total
and dissolved lead, even though the potential for lead contamination
had been removed now that the remedy is complete.
Prior to receiving the January 27, 2011 letter from PADEP, Gould
followed the same protocols for sampling the basin discharge that
were in place during construction.
(Click here for an explanation of the procedures in place during
construction.) After Substantial Completion was achieved on
August 27, 2010, there was a period of discharge above 250 NTUs that
is further described below.
(Click here
to go back to the Stormwater Management System page.)
STORMWATER DISCHARGE INFORMATION SEPTEMBER 30, 2010 to OCTOBER 16, 2010
INCLUDING DISCUSSIONS ON DISCHARGES ABOVE THE PERFORMANCE STANDARD
A
substantial rain event, one that has a 2% chance of occurring in any year
(commonly referred to as a 50-year storm)
occurred
September 30 to October 1, 2010 delivering approximately 4.98 inches of rain to
the Marjol Battery Site and the surrounding
area (based on weather information from the Avoca, PA airport).
According to
the Jermyn gauging station, approximately 5.52 inches of rain fell in 24 hours.
Gould inspected the site several times throughout the rain event and did not
observe any major erosion issues on the site. The sedimentation basin functioned
as designed throughout the rain event. Gould monitored the flow in the discharge
channel and the turbidity level at the discharge point throughout the rain
event. Early in the storm, the turbidity level remained below the turbidity
standard of 250 NTUs, but as the heavy
rains continued, the flow across the Site and into the sedimentation basin
increased such that turbidity readings in the afternoon on September 30, 2010 and on October 1, 2010 were above the turbidity standard.
Subsequent rain events occurred throughout the period from October 4 through 16,
2010. In order to
gain capacity in the basin and in an attempt to keep up with the inflow of stormwater
run-off into the basin, discharge from the basin was allowed in a controlled
manner through the skimmer even though the turbidity levels were above the
standard on some days.
Water samples
(analyzed for total and dissolved lead) were collected at the discharge point
on days when turbid discharge took place. The dissolved lead results
(through October 8, 2010) were all below the
laboratory detection limit of 1.0
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead results were at or
below 50.2
µg/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.
USEPA, PADEP, and
Throop Borough were regularly kept informed by e-mail on stormwater management activities during the
period from September 30 to October 17, 2010 and with PADEP’s concurrence,
Gould submitted a formal report to PADEP, once the analytical data for the series of storm
events had been received, on October 27, 2010.
(Click
here to review the September 30 to October 16, 2010 Stormwater Discharge Report.)
See below for a description of the daily stormwater management activities for the period from September 30, 2010 through
October 16, 2010:
September 30
to October 1, 2010 - The regional storm event that occurred September 30 to October
1, 2010 delivered approximately 5.5 inches of rain to the Marjol Battery
Site and the surrounding area (based on rainfall information from the USGS
gauging station in Jermyn, PA).
Gould monitored the flow in the discharge channel and the turbidity
level at the discharge point throughout the rain event. Early in the
storm, the turbidity level remained below the turbidity standard of
250 NTUs (turbidity was 67.1 NTUs at 7:45
am), but as the heavy rains continued, the flow across the Site and into the
sedimentation basin increased such that turbidity readings at 1:50 pm on
September 30, 2010 and at 8:05 am on October 1, 2010 were far above the
turbidity standard (2,446 NTUs and 1,167 NTUs respectively).
Water samples
(analyzed for total and dissolved lead) were collected at the discharge point
during September 30 and October 1, 2010 turbidity exceedances. The dissolved lead result
was 0.26
µg/L
on September 30, 2010 and 0.36
µg/L
on October 1, 2010. The NPDES permit standard for maximum
dissolved lead for the Site is 650
µg/L.
The total lead result was 50.2
µg/L
on September 30, 2010 and 25
µg/L
on October 1, 2010. There is not an NPDES standard for
total lead.
Although the discharge water was turbid, it was not feasible to
stop the discharge because the basin is not designed to hold all of the
water from a storm like this one without discharging and water would have
overflowed through the emergency spillway. It was safest to allow the
discharge to continue through the outlet structure rather than allow the
water level to build up and overtop the emergency spillway because even
though the spillway is armored with stone, a lot of water passing over it
could cause erosion or failure of the berm.
Gould and Throop Borough were in communication throughout the rain event to
discuss stormwater management activities at the Site.
With the
September 30 - October 1, 2010 storm event over (and therefore no additional
flow going into the basin), the skimmer in the basin was flipped on Friday
afternoon, October 1, 2010, to stop discharge from the sedimentation basin
and a flocculent (Pond Clear) was added to the basin to allow the sediments
to settle out.
October 2 and
3, 2010
– There was no discharge from the sedimentation basin.
October 4,
2010
- On Monday, October 4, 2010, at approximately 2 pm, due to the elevated
water levels in the basin and the continuing and forecasted rain at the
Site, it was determined that if the basin was not permitted to discharge
through the skimmer the water level in the basin would rise to the top of
the outlet structure and discharge at a higher flow rate through the top of
the outlet structure. Therefore, in order to gain capacity in the basin and
in an attempt to keep up with the inflow of stormwater run-off into the
basin, the skimmer was flipped to allow discharge from the basin in a
controlled manner even though the turbidity levels were still above the
standard. The turbidity level at the discharge point after 15 and 30 minutes
was 297 and 310 NTUs, respectively.
At 3:27 pm, a
turbidity reading of 314 NTUs was obtained.
Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.025
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 12.5
µg/L. There is not an NPDES standard for
total lead.
October 5, 2010 - On Tuesday, October 5, 2010, at 8:10 am, a
turbidity reading of 287 NTUs was obtained.
Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.17
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 10.6
µg/L. There is not an NPDES standard for
total lead.
October 6, 2010 - On Wednesday, October 6, 2010, discharge
continued through the skimmer. At 9:00 am, a
turbidity reading of 256 NTUs was obtained.
Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.4
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 9.8
µg/L. There is not an NPDES standard for
total lead. Flow through the top of the outlet
structure was occurring when the 9:00 am turbidity reading was obtained.
October 7, 2010 - On Thursday, October 7, 2010, discharge
continued through the skimmer. At 8:30 am, turbidity readings of 251 and
283 NTUs were obtained.
Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.56
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 9.3
µg/L. There is not an NPDES standard for
total lead. The water level dropped to a point
of 6 to 8-inches below the outlet structure by 8:30 am.
October 8, 2010 - On Friday, October 8, 2010, discharge
continued through the skimmer. At 8:10 am, a turbidity reading of 188 NTUs
was obtained. Based on this reading, the basin was allowed to continue to
discharge. An additional turbidity reading was taken at 1:20 pm; the result was
178 NTUs. Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.4
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 5.8
µg/L. There is not an NPDES
standard for total lead. The basin continued to discharge over the
weekend.
October 9 and 10, 2010 - Discharge from the sedimentation basin
continued over the weekend.
October 11, 2010 - On Monday, October 11, 2010, discharge
continued through the skimmer. At 9:00 am, a turbidity reading of 95.5
NTUs was obtained. No samples were taken for total and dissolved lead.
October 12, 2010 - A rain event occurred overnight with a total of
0.76 inches over 6 hours. This information was obtained from a USGS rain gauge
located in Jermyn, PA approximately 9 miles northeast of the site. At 7:35
am, a turbidity reading of 346 NTUs was obtained. Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.15
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 15
µg/L. There is not an NPDES
standard for total lead. The skimmer was
flipped to discontinue discharge from the sedimentation basin and a flocculant
(i.e., Pond Clear) was added to the sedimentation basin to allow the sediments
to settle out.
October 13, 2010 – There was no discharge from the
sedimentation basin in order to allow time for the flocculants to help settle
out the sediments.
October 14, 2010 – The skimmer remained in the "no
flow" position until 3:00 pm. The water level was just below the
baffle near the outlet structure. As rain was forecasted and
received (approximately 0.34 inches) the water was allowed to
discharge to allow capacity for flow into the basin. Turbidity
readings were 324 NTUs at 3:15 pm, 312 NTUs at 3:30 pm, and 287 NTUs
at 3:35 pm. Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at 3:15 pm. The dissolved lead result was 0.024
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 14.7
µg/L. There is not an NPDES
standard for total lead.
October 15, 2010 – Discharge through the skimmer
continued to be allowed in order to gain additional capacity in the
basin and to allow the sediment basin to function with the baffle
and silt curtain. A turbidity readings of 300 NTUs was collected at
8:15 am. Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.037
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 12
µg/L. There is not an NPDES
standard for total lead.
October 16, 2010 – Discharge through the skimmer
continued to be allowed in order to gain additional capacity in the
basin and to allow the sediment basin to function with the baffle
and silt curtain. A turbidity readings of 260 NTUs was collected at
11:25 am. Water samples
(analyzed for total and dissolved lead) were also collected at the discharge point
at this time. The dissolved lead result was 0.023
µg/L. The NPDES permit standard for maximum
dissolved lead for the Site is 650 ug/L. The total lead result was 10
µg/L. There is not an NPDES
standard for total lead.
A report
on stormwater management discharge for the period from September 30 through
October 16, 2010 was submitted to PADEP on October 27, 2010. (Click
here to review the September 30 to October 16, 2010 Stormwater Discharge Report.)
(Click here to go back to the
Stormwater Management System page.)
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