• Stormwater Structures
• Stormwater Sampling and Discharge 
• Containment Area Overflow
• Stormwater Discharge Above the Performance Standard - January 25, 2010
• Calendar with Daily Stormwater and Sediment Data and Information

STORMWATER STRUCTURES

In order to control stormwater at the Site both during and after construction activities 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
(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 hold water from a 100-year storm; rainwater that falls on the Site is directed to the basin where sediment will settle out prior to the water being discharged since water from areas without grass yet that drain to the basin may carry sediment. Once the remediation at the Site is complete and grass is growing, the basin is converted to a stormwater management basin.

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. 

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.

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.  (Click here to view a picture of water discharging from the outlet structure.)
    

 

STORMWATER SAMPLING AND DISCHARGE

The 100% Design Plan calls for stormwater from the clean areas of the Site to be collected in the new temporary sediment basin. Sediment that is carried along with the stormwater settles out in the basin, and stormwater collected in the basin is 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 is designed so stormwater falling on contaminated areas of the Site does not flow into the basin, but is retained within the contaminated areas by berms.

CONTAINMENT (CAP) AREA OVERFLOWS

As a result of heavy rains in July and August, 2009, water overflowed the Containment (cap) Area (CA) (which has contaminated material in it) into a drainage feature (the South Swale) outside of the CA and into the basin on July 31, August 10, and on August 12, 2009. While every effort has been made to keep this type of overflow from occurring, the possibility of it happening was considered in the design, and so the overflow water flowed into the sediment basin as it is supposed to do where the lead contaminated sediment could settle out before the water is discharged. Tests conducted after the overflows show that the discharges were well below the limits that were set by the State to protect the Lackawanna River.

When each of the overflow incidents has occurred, the skimmer in the basin has been raised (if it wasn’t already) to prevent the flow of water from the basin through the discharge channel. Water in the basin was tested for turbidity and when it was below the performance standard, the skimmer was lowered to allow water to discharge.  After the overflow in July, the basin water was also tested for total and dissolved lead. Any sediment and battery casings that have floated onto the CA berm and into the swale were removed and placed back into the CA. XRF analysis (an XRF is a portable instrument used for testing lead concentration in substances such as soil) for lead has been performed on the berm and in the swale to see if the overflow contaminated any previously clean areas.

If the soil lead levels were above the cleanup level, then soils on the berm and swale were excavated and placed into the CA. The excavated areas were rechecked with the XRF to be sure lead levels were below the cleanup standard.

After the first overflow, a meeting was held to discuss how to better control an overflow if it happened again. In order to get more room to hold the contaminated water so that it would not go off-site, it was decided to pump the contaminated water from the CA to a strip pit that was previously excavated – Area B – instead of back into the CA as the practice had been. Area B will be tested near the end of the project and will be re-excavated if necessary with any contaminated material being placed in the CA and solidified. Subsequent efforts after the overflows focused on making sure that the pumps were ready when rain occurred during the night and that the pumps could handle all of the water. While the overflows are not what we would like to see, the important point is that the lead is being contained within the site as it is supposed to be while we are managing the water as best we can with the unfavorable weather we have been having.

Reports with the details of the overflows have been submitted to EPA and DEP. Click on the links below to review the reports. 

Report on July 31, 2009 Overflow                                Report on August 10 and 12, 2009 Overflows

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 (a measurement of the cloudiness of the water which is caused by sediment) 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 is 64.4 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.

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

EPA and DEP 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 Non-Compliance Report.)