Stormwater Discharge Above the Performance Standard - Monday, January 25, 2010

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 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 was 64.4 ug/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.

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

USEPA and PADEP 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 January 25, 2010 Non-Compliance Report.)

Page Last Modified Tuesday October 19, 2010 03:48:15 PM