Draft

February 5, 2009

Ref: PF/NPDES/PER

The blast furnace recycle system consists of two thickeners (i.e., one for each furnace), a 

cooling tower and a pump house for recirculating treated process water for reuse at the 

blast furnaces. Periodic blowdown from or lake water make-up to this system occurs

throughout the day in order to maintain a hydraulic balance within the recycle system. 

The blowdown is discharged to the plant’s dirty industrial wastewater (DIW) sewer 

system for further treatment at the Secondary Wastewater Treatment Plant (SWTP) prior 

to discharge to surface waters of the State. In the event the recycle system experiences 

elevated concentrations of cyanide, a steady-state blowdown can be directed to an 

alkaline chlorination system to destroy the cyanide before discharge to the SWTP.

The sinter plant has its own dedicated treatment plant that receives all of the gas cleaning 

blowdown from the sinter plant and minor quantities of filtrate from the mechanical 

dewatering of BOF sludge. Excess moisture is added to this system by virtue of the 

process and is blown down to the Reclamation Services Building (RSB) for treatment. 

After pH adjustment (we try to maintain a pH of about 9.3) and the addition of 

flocculation/coagulation polymers, the wastewaters are directed to the final thickener for 

preliminary clarification. The effluent of the final thickener discharges to the Dirty

Industrial Wastewater (DIW) sewer system for further treatment at the SWTP. 

The basic oxygen furnace recycle system consists of two thickeners that treat the gas 

cleaning process waters prior to recycling back to the gas cleaning system or blowdown 

to the DIW sewer system for further treatment at the SWTP.

The continuous casters (2) are equipped with scale pits for the removal of suspended 

solids and oil. The hot forming mills (two plate mills and the hot strip mill) are also 

equipped with scale pits and oil skimming equipment. The facilities recycle a portion of 

the scale pit effluent water for use in the production process and the balance is discharged 

to the DIW sewer system for further treatment at the SWTP.

Wastewaters generated from the hot dip (galvanizing) coating line are filtered prior to 

discharge to the DIW in order to remove particulate zinc. Waste pickling acids are either 

used on site to neutralize wastewaters, sold for off-site recycling or disposed of by deep 

well injection. Pickling rinsewaters and fume scrubber blowdowns are combined with 

pretreated wastewaters from the cold rolling operations and directed, via the DIW sewer 

system, to the SWTP for final treatment.

Contaminated groundwater from the ore dock area is recovered and used as a 

replacement for lake water in the gas cleaning systems of either the Sinter Plant or the

Blast Furnaces. As noted above, the blowdowns from these systems receive initial 

treatment at the generation site and secondary treatment at the SWTP.

Most of the facility’s wastewaters receive primary treatment at their source and final 

treatment at the SWTP. Final treatment includes pH adjustment, oil separation, 
flocculation/coagulation and clarification prior to discharge through several open channel 

conveyances before reaching the East Branch of the Little Calumet River. Sludges 

generated by the SWTP will be disposed on-site in a permitted Type 1 solid waste landfill

(to be constructed). Any leachate generated by the landfill will also undergo preliminary

treatment prior to discharge to the DIW and SWTP. 

The SWTP effluent is routed through two lagoons prior to discharge through internal 

Outfall 011 and final Outfall 001 into the East Branch of the Little Calumet River. The 

lagoons are equipped with aerators for temperature control. Lake Michigan water can 

also be added to the Outfall 011 discharge during warm weather months for additional 

temperature control.