NOTE: ALL PRINTED EQUIPMENT OPERATING PROCEDURES ARE CONSIDERED UNCONTROLLED UNLESS STAMPED IN RED: CONTROLLED DOCUMENT.

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1 EOP 7K OPERATION OF AEROBIC DIGESTER AND SPRAY IRRIGATION PROCEDURE 1-11 I. INTRODUCTION II. BACK FLUSHING SPRAY IRRIGATION PUMPS III. PUMPING SLUDGE IV. CLEANING BASKET STRAINERS V. APPENDIX A (8K02 Pumping Station Drawing) VI. APPENDIX B (Overview) VII. APPENDIX C (Spray Irrigation Log) VIII. APPENDIX D (Spray Irrigation Diagram) IX. APPROVALS

2 Page 2 I. INTRODUCTION In order to provide for the safe and legal disposal of waste activated sludge that is generated during the treatment of wastewater, it is necessary to operate and manage the aerobic digester and spray irrigation fields in a safe, effective, and efficient manner. The accidental discharge or application of waste activated sludge onto an area other than the spray irrigation fields or into the sludge dewatering equipment could result in a discharge permit violation. Some examples are: Sludge being sprayed over the containment areas such as the berms. This could allow digested sludge to enter creeks or adjoining lands not designated for land application of sludge. Sludge from a damaged or ruptured underground line entering the holding pond via the creek west of the 7K01 area.

3 Page 3 II. BACK FLUSHING SPRAY IRRIGATION PUMPS NOTE #1: See Appendix A for drawing diagram. NOTE #2: Because of the trash that accumulates in the aerobic digester, the intake screens on the sludge and spray irrigation pumps may become partially plugged. This can be determined by a drop in pump discharge pressure below the normal range of pounds. Short-term relief from the plugging may be achieved by back flushing the pump(s) concerned with river water. A river water line is available at the east side of the pump structure and may be used for this purpose. To accomplish this, the following steps are taken: 1. Place the selector switch for the pump motor control in OFF. 2. Close the pump discharge valve on the pump that is to be back flushed. This will be valve ADV-7, ADV-10 or ADV Connect the flexible 2" hose from the 2"-riverwater line (ADV-14) to the 2" valve coming off the pump discharge (ADV-18, ADV-17 or ADV-16). 4. Open the 2"valve ADV-16, ADV-17 or ADV Open the 2" river water valve ADV-14 so river water will flow through the pump discharge and down through the pump suction line. 6. After about 1 minute, you should observe turbulence around the pump suction pipe. This indicates the river water is flowing through the pump and washing material away from the pump intake screen. 7. Allow the river water to back flush the pump for about minutes.

4 Page 4 8. When the back flushing is complete, reverse the seven preceding steps and repeat the steps for any other pumps requiring back flushing.

5 Page 5 III. PUMPING SLUDGE To 6M08 Using SD-10 Sludge Pump See Appendix A for drawing diagram. 1. Open seal water ADV-5 to SD-10 sludge pump. 2. Close back flush valve ADV Close sludge header isolation valve ADV Close sludge header isolation valve ADV Open sludge pump SD-10 discharge valve ADV Open sludge header valve ADV Open sludge pump recirculation valve ADV-3, two full turns. 8. Place the SD-10 local pump ON-OFF-AUTO selector switch in AUTO. The pump then can be started from any DCS terminal that has the waste water treatment environment down loaded. To 6M08 Using G-SIP1 Sludge Pump See Appendix A for drawing diagram. 9. Open seal water ADV-9 to G-SIPI sludge pump.

6 Page Close back flush valve ADV Close sludge header isolation valve ADV Close sludge header isolation valve ADV Open sludge pump G-SIPI discharge valve ADV Open sludge header valve ADV Open sludge header crossover valve ADV Open sludge pump recirculation valve ADV-3, two full turns. 17. Place the G-SIPI local pump ON-OFF-AUTO selector switch in AUTO. The pump then can be started from any DCS terminal that has the waste water treatment environment down loaded. To 6M08 Using G-SIP2 Sludge Pump See Appendix A for drawing diagram. 18. Open seal water valve ADV-11 to G-SIP2 sludge pump. 19. Close back flush valve ADV Close sludge header isolation valve ADV Close sludge header isolation valve ADV-4.

7 Page Open sludge pump G-SIP2 discharge valve ADV Open sludge header valve ADV Open sludge header crossover valve ADV Open sludge pump recirculation valve ADV-3, two full turns. 26. Place the G-SIP2 local pump ON-OFF-AUTO selector switch in AUTO. The pump then can be started from any DCS terminal that has the waste water treatment environment down loaded. To The Spray Fields NOTE 1: See Appendix A for drawing diagram. NOTE 2: Any or all of the three existing pumps may be used to pump sludge to the spray irrigation fields. A minimum of 2 pumps are required when spraying sludge. 27. Open seal water valves ADV- 5, 9 and Close sludge header isolation valve ADV Close sludge header isolation valve ADV Close back flush valves ADV-16, 17 and Open sludge pump discharge valves ADV-7, 10 and Open sludge header valve ADV-8.

8 Page Open sludge header crossover valve ADV Open sludge valve ADV Ensure ADV-13 valve is closed. 36. Place the local pump ON-OFF-AUTO selector switches in AUTO. The pumps can be started from any DCS terminal that has the waste water treatment environment down loaded. 37. Start and run a minimum of 3 surface aerators before spraying. This will ensure adequate suspension of the solids in the liquid to be sprayed. 38. Go to the spray field and open the inlet valve to each of sections that are going to be sprayed (refer to Appendix D). 39. Ensure the pump seal water is open to the pump. 40. Start the pumps. The normal operating range header pressure is psig. 41. Go to each section being sprayed and ensure all sprinklers are working properly. 42. Adjust each nozzle to ensure that the sludge spray pattern remains inside the berm or containment areas. 43. Check the pump discharge pressures hourly to ensure the pump intake screen or strainer baskets have not become plugged.

9 Page Check the sections of field being sprayed frequently to ensure all sprinklers are working properly and run-off is not taking place. 45. Check catch basins to ensure they are not obstructed to ensure runoff will be collected and returned to the WWT system. 46. Collect a daily sludge sample from the pump discharge and take to 7K01 lab for % total solids analysis (refer to EOP 7K for solids analysis). The NPDES permit requires a daily log for recording gallons sprayed each day, percent solids, field conditions and weather conditions. Refer to Appendix C for an example of the spray irrigation log.

10 Page 10 IV. CLEANING BASKET STRAINERS Strainer A CAUTION: The following additional PPE is required when cleaning the basket strainers. rubber gloves See Appendix A for drawing diagram. 1. Place the local motor control switches to all three sludge pumps in OFF. 2. Close header valve ADV Open valve ADV-16 to relieve any pressure on the basket strainer. 4. Slowly remove the two hold down bolts on the strainer housing lid. 5. Remove the dirty basket strainer from the housing. 6. Take the dirty basket to the water spigot located on pump platform and wash off trash. 7. Place the cleaned strainer basket back into the housing. 8. Install a new gasket under the strainer housing lid if needed. 9. Replace housing lid and tighten hold down bolts. 10. Close valve ADV-16.

11 Page 11 Strainer B CAUTION: The following additional PPE is required when cleaning the basket strainers. rubber gloves See Appendix A for drawing diagram. 11. Place the local motor control switch to all three sludge pumps in OFF. 12. Close header valve ADV Open valves ADV-17 and ADV-18 to relieve any pressure on the basket strainer. 14. Slowly remove the two hold down bolts on the strainer housing lid. 15. Remove the dirty basket strainer from the housing. 16. Take the dirty basket to the water spigot located on pump platform and wash off trash. 17. Place the cleaned strainer basket back into the housing. 18. Install a new gasket under the strainer housing lid if needed. 19. Replace housing lid and tighten hold down bolts. 20. Close valves ADV-17 and ADV-18.

12 Page 12 V. APPENDIX A (8K01 Pumping Station Drawing) SEAL FLUSH WATER ADV-3 ADV-3 ADV-1 To 6M08 To Spray Fields ADV-4 ADV-2 W.A.S. from 7K01 NORTH ADV-5 SD-10 ADV-6 ADV- 16 ADV-7 ADV-8 AEROBIC DIGESTER ADV-9 STRAINER BS-A STRAINER BS-B G-SIPI ADV-10 INLET SCREEN TO THE PUMP WELL ADV-17 ADV-11 G-SIP2 ADV-12 ADV-18 ADV-13 ADV-15 AEROBIC DIGESTER ADV-14 ADV-19 To Polishing Basin 2 River water line from 7K01 yard ADV-20 To Aeration Basin

13 Page 13 VI. APPENDIX B (Overview) LAND APPLICATION OF SLUDGE BY SPRAY IRRIGATION ARK is permitted to dispose of waste activated sludge by land application through the use of a spray irrigation system. The land area over which the sludge may be applied consists of three fields comprising about 95 acres. A number of factors determine when sludge may or may not be "sprayed." Among these are temperature, precipitation, condition of the fields, condition of the equipment, odor levels, and wind direction. Refer to ARK s NPDES Discharge Permit # AR located in the 7K01 control room. Part III, Pages 1-5, pertain to the land application of sludge. All land application of sludge will be done under the direction of the Utilities Environmental Team. The WWT Biologist or a member of the Utilities Environmental Team should address any questions, problems or concerns. Sludge is normally applied to the fields from early spring to late fall depending on the weather conditions. Sludge must be applied at rates that saturate the soil without significant harm to the vegetation or cause excessive runoff. Each individual nozzle will flow approximately ~ 35 gpm, depending on the sludge pump discharge pressure. If you spray a section that has 16 nozzles for one hour you will have sprayed ~ 34,000 gallons. (mg sprayed) (8.34 lbs/gal) (sludge concentration in ppm) 2000 lbs/ton = Tons Applied Good management practices must be followed in order to saturate the ground without over-spraying to the point of significant smothering of the grass. This requires frequent monitoring of the spray fields. With enough time and experience, an operator will learn how long each of the different sections can be sprayed, depending on the weather and field conditions at any given time. Due to the varied landscape of each section some spots will dry faster than others. At times it will be necessary to valve out individual nozzles so a section can be sprayed. Most sections will have 4 8 spray nozzles. MAINTAINING SOLIDS LEVEL IN AEROBIC DIGESTER The percentage of solids in the digester should range between 1.0 and 5.0. Greater than 5% sludge causes the sludge to be too thick for land application. Less than 1.0% sludge wastes the storage space in the digester. Normal waste sludge percentage is ~ 1.5%. The sludge wasting rate is determined by the sludge age and concentration in the aeration system.

14 Page 14 The aeration basin total suspended solids should be maintained ~ 5000 ppm or 0.5% and the volatile suspended solids should be maintained ~ 4000 ppm or 0.4%. Sludge wasting rates can be determined by calculating the aeration basin BOD loading. For every pound of BOD treated ~ 0.5 pounds of new bacteria is formed. Example: If you are treating 10,000 lbs. per day of BOD then you generating around 5,000 pounds of new bacteria. In the winter months when sludge cannot be land applied and no storage space is available for wasting sludge, the sludge concentration may rise significantly in the aeration system. It is not uncommon for the aeration total suspended solids to reach the ppm range during the winter months. SPRAY FIELD MAINTENACE During the summer months it will be necessary to have the spray fields mowed as needed. SPRAY FIELD LIMING We will apply lime to the spray fields if the soil ph is < 5.7. SUMMER TIME SPRAYING In the summer months when the temperature and evaporation rates are high, each section can normally be sprayed 1-2 times per week. Each section can be sprayed for 1 3 hours, which would be ~ 90,000 gallons of sludge at a flow rate of 500 gpm. Each section should be checked frequently to ensure that over spraying is not occurring. SPRING AND FALL SPRAYING In the early spring and late fall months when we normally get most of our precipitation, land application of sludge will be greatly reduced. By isolating individual nozzles, each section can normally be sprayed for 1 hour which would be ~ 30,000 gallons of sludge. Each section should be checked hourly to ensure that over spraying is not occurring. The following consideration and actions shall be taken when applying sludge to the land by spray irrigation (spraying). No spraying will be done if any of the following conditions exist:

15 Page 15 Ambient air temperature is below freezing. Ground is frozen or covered with snow. Precipitation is occurring or imminent. Fields that are saturated.

16 Page 16 VII. APPENDIX C (Spray Irrigation Log) The Spray Irrigation Log can be found on the Utilities web site by clicking on the link below. Spray Irrigation Log

17 Page 17 VIII. Appendix D (Spray Irrigation Diagram) #1 SPRAY FIELD TO FIELD #2 1S 1N 2S 2N 3S 3N 4S 4N FROM AEROBIC DIGESTER PUMPS FROM AERABIC PUMPS TO #3 FIELD

18 Page 18 #2 SPRAY FIELD TO # To East side # 3 Field

19 Page 19 #3 Spray Field West Side DRAIN DRAIN 41 From Field # DRAIN 40 DRAIN DRAIN 38

20 Page 20 #3 Spray Field East Side AIR MONITORING BUILDING 44 DRAIN FROM FIELD #2 46 DRAIN VALVE 45 DRAIN VALVE

21 Page 21 IX. APPROVALS ESRC Approval Date: 8/16/11 Version Approved: 1-11 Process System Representative: (if applicable) Jim Ramsey Area Manager: S.G. Case