13044
Title
11 Primary Clarifier Shutdown
Shutting down a clarifier involves taking the scum collector and sludge collection units offline. Also, the sludge transfer piping and standby primary sludge pump is re-valved to drain the offline clarifier.
SOP Identification Number
SOP Identification Number:
1100_Shutdown
Purpose and scope
Purpose and scope:
Clarifiers are typically shut down for process control or maintenance. The SOP is generally the same for both reasons.
Health & Safety Warnings
Health & Safety Warnings:
- Watch for open tanks, vaults and channels when covers are removed. Install cones at opening if covers are to remain off.
- Potential confined space entry at primary sludge pump vault.
Cautions
Cautions:
- Ensure that adjustments to valves, drives, pumps, etc., all correspond to the clarifier being taken offline.
- Do not over tighten valves.
- Allow sludge collector to run long enough to give the clarifier being taken offline long enough for solids to settle.
- Make sure the Primary Sludge Pump check valve rises after the pump is put into HAND. This will indicate if the pump is draining the clarifier. If the check valve does not rise, check the suction and discharge valve positions to ensure they are open. If the valves are open, the drain lines may be blocked and need to be flushed.
- Monitor influent flows to the clarifier(s) that remain online in order to prevent negative impacts to system processes.
- Don’t allow sludge collector to run until the clarifier is “dry” as it could damage the equipment.
- Watch for scum build up after the scum collector is taken out of service.
- Ensure that information is recorded to the log book.
Potential Interferences
Potential Interferences:
- Plugged drain lines.
- Imbalanced influent flows to the online clarifiers and resulting impacts to system processes.
Personnel Qualifications
Personnel Qualifications:
Operator I, knowledge of primary treatment processes and SCADA controls.
Equipment, Supplies, Required Tools
Equipment, Supplies, Required Tools:
Valve keys or other tool to open and close valves.
Quality Control/Quality Assurance Activities for the Procedure
Quality Control/Quality Assurance Activities for the Procedure:
- Record activity to log book.
- Self-check of clarifier being taken out of service with associated equipment and systems that are affected.
- Monitor levels and flows in on-line clarifiers for overflows or flushing.
- Monitor off-line clarifier for decreasing liquid levels.
Videos
Procedure
Procedure:
Primary clarifiers may be shut down for process control or for maintenance. Typically, the SOP is the same for both purposes.
Steps 1 – 2 take place “upstairs” at the Primary Clarifier Deck.
1. Isolate the Channel:
a. Identify the influent slide gate locations associated with the primary clarifier to be taken out of service {tag nos. 1101VLV1181B, 101VLV1182B, 101VLV1183B, 101VLV1184B, 101VLV1185B}. Depending on the primary clarifier to be taken out of service, there will be a minimum of two gates or a maximum of three gates. Install slide gates to the primary clarifier influent channel at those locations. Slide the gates fully into place. If the level begins to drop and flow over the weirs has discontinued within the first 15 minutes, the gates have been successfully installed and influent flows are closed to that clarifier..
b. Identify the two influent valves {tag nos. 1101VLV1181 & 1101VLV1181A, 1101VLV1182 & 1101VLV1182A, 1101VLV1183 & 1101VLV1183A, 1101VLV1184 & 1101VLV1184A, 1101VLV1185 & 1101VLV1185A} associated with the primary clarifier to be taken off line. Remove aluminum grates to gain access to the valves. Manually close the valves with the T-handle valve key. Turn clockwise until they stop – this could take up to 100 turns. Close 100%, but do not over tighten the valves.
2. Take Scum Collector Out of Service:
a. If the single drive unit clarifier #1 {tag no. 1101MTR1724} is to be taken out of service, go to Step 2.d.
b. If both clarifiers on dual drive unit #2/#3 or unit #4/#5 {tag nos. 1101MTR1725 & 1101MTR1726} are to be taken out of service, go to Step 2.d.
c. If the clarifier to be taken out of service is on a dual drive and the other clarifier is to remain in service, skip Step 2.d and go to Step 2.e. For example, if #2 is taken off line but #3 remains online, go to Step 2.e.
d. Locate the control box at the south east corner of the clarifier. Turn the local control switch from AUTO to the OFF position if the skimmer is in the upright position. If the skimmer is in a cycling mode, wait until the skimmer has completed the cycle. Skip Step 2.e and go to Step 2.f.
e. Locate the control box at the south east corner of the clarifier. Turn the local control switch from AUTO to the OFF position if the skimmer is in the upright position. If the skimmer is in a cycling mode, wait until the skimmer has completed the cycle. Slide the coupling along the shaft so the teeth are separated. Turn the local control switch from OFF back to the AUTO position.
f. After the channel is isolated, continue to run the Sludge Collector for approximately 30 minutes. This allows most of the sludge to settle before it is pumped to solids handling.
g. When levels in the clarifier are only about a foot deep, start the sludge drain cycle. Due to the hydraulics of the sludge removal system, pumping is required once the level reaches about 12 inches.
Steps 3 - 7 take place “downstairs” at Gallery #2.
3. Start Primary Sludge Drain Cycle:
a. Log in to a SCADA workstation and select the Sludge Pump Room screen and locate the skimmer control. Move over toggle switch graphic for that clarifier and click the left button. The switch should indicate that the skimmer control for that clarifier is OFF.
b. At the SCADA workstation, select “Skipped” for the actuated Rotork Primary Sludge Valves that are associated with the primary clarifier being taken out of service {tag nos. 1102OPS1677, 1102OPS1677A, 1102OPS1677B, 1102OPS1677C, 1102OPS1677D, 1102OPS167E7, 1102OPS1677F, 1102OPS1677G, 1102OPS1677H, 1102OPS1677I}.
c. Turn the local actuated Rotork Primary Sludge Valve switch to the STOP/CLOSED position by turning the valve handles clockwise so they are perpendicular to the piping {tag nos. 1102OPS1677, 1102OPS1677A, 1102OPS1677B, 1102OPS1677C, 1102OPS1677D, 1102OPS167E7, 1102OPS1677F, 1102OPS1677G, 1102OPS1677H, 1102OPS1677I}. The valve handles should now face outward into the gallery walkway, indicating that they are not in their normal position.
d. Manually open the two drain valves that are located below the actuated Rotork valve and are associated with that clarifier {tag nos. 1102VLV1679, 1102VLV1679A, 1102VLV1679B, 1102VLV1679C, 1102VLV1679D, 1102VLV1679E, 1102VLV1679F, 1102VLV1679G, 1102VLV1679H, 1102VLV1679I}.
e. Re-Valve the Standby Primary Sludge Pump: Primary sludge piping is gray and located above the drain piping. Drain piping is white and located below the primary sludge piping.
i. Remove the grates from the Primary Sludge Pump vault for the pump that is currently on stand-by. Suction piping is located in the vault. Manually open the suction drain valve located on the lower white piping {tag nos. 1102VLV1679J & 102VLV1679K}. Manually close the suction sludge transfer valve located on the upper gray piping {tag nos.1102VLV1100 & 1102VLV1200}. Replace the grates.
ii. At the overhead discharge piping, manually open the discharge drain valve located on the lower white piping {tag nos. 1102VLV1100D & 1102VLV1200D}. Manually close the discharge sludge transfer valve located on the upper gray piping {tag nos. 1102VLV1100A & 1102VLV1200A}.
iii. At the local control panel, switch the stand-by pump to HAND and start the pump {tag nos. 1102PMP1100 & 1102PMP1200}. The check valve should rise to indicate you are successfully draining the clarifier. If the check valve does not rise, check the suction and discharge valve positions to ensure they are open. If the valves are open, the drain lines may be blocked and need to be flushed.
iv. At the SCADA workstation, locate the pump switch graphic and click the left button to HAND control. Locate the VFD speed control and set to 80% of range.
v. Periodically monitor the sludge level in the clarifier to determine when the pump should be turned off. Generally, it takes approximately 5 - 7 hours to drain a primary clarifier.
Steps 4 – 5 take place “upstairs” at the Primary Clarifiers.
4. Remove an aluminum cover from the primary clarifier so the water level can be monitored. IF THE COVER IS TO REMAIN OFF, INSTALL SAFETY TRAFFIC CONES AROUND THE OPENING. The water level should drop. If it doesn’t, check the clarifier influent slide gates that were closed in Step 1 to ensure that they are fully seated.
5. Take Sludge Collection Unit Drive Offline: Extended operation of the collector after the primary clarifier has been drained could damage the equipment. While the sludge collector drive is still in operation, inject 10 (typical) pulses of grease to each grease fitting sprocket. This insures a smooth start up of the unit, even if the clarifier remains out of service for more than a week.
a. If the single drive unit for clarifier #1 {tag no. 1101MTR1721} is to be taken offline, go to Step 5.d.
b. If both clarifiers on dual drive unit #2/#3 or #4/#5 {tag nos. 1101MTR1722 & 1101MTR1723} are to be taken out of service, go to Step 5.d.
c. If the clarifier to be taken out of service is on a dual drive and the other clarifier is to remain in service, skip Step 5.d and go to Step 5.e. For example, if #2 is taken off line but #3 remains online, go to Step 5.e.
d. Turn the switch to the OFF position.
e. Turn the local control switch to the OFF position and then to the REVERSE position. Press the Jog switch button. Slide the coupling along the shaft so the teeth are separated. To put the other coupling back into service, turn the local control switch to Forward and OFF. Slide the coupling back until the drive sprocket is fully engaged. Turn the local control switch to AUTO and then to the FORWARD position.
Step 6 takes place in the Operator’s Office
6. Record Data to Operator’s Log Book: Record primary clarifier shutdown activities to the log book with other entries for the day. Include the following in the entry:
a. Operator(s) that performed the Primary Clarifier Shutdown SOP.
b. Which primary clarifier was taken off-line and the approximate time that the process began.
c. Reason for shutdown (routine maintenance or process control).
d. Duration of sludge drain cycle.
e. Note the approximate time that the SOP was completed.
f. Note any unusual conditions with flows, levels, odors or other process issues.
g. Note any damage, wear, or required maintenance on equipment.
Data & Records Management, Calculations, Forms, Reports
Data & Records Management, Calculations, Forms, Reports:
- Update log book.
- Update maintenance records (if applicable).
- Report any maintenance or attention that is required.
Limits/Criteria for Data/Results
Limits/Criteria for Data/Results:
- Consistent treatment results during and after clarifier shutdown.
- Solids are removed from off-line clarifier.
Equipment
Equipment:
EQUIPMENT | TAG NUMBER |
Clarifier #1 & #2 Slide Gate | 1101VLV1181B |
Clarifier #2 & #3 Slide Gate | 1101VLV1182B |
Clarifier #3 & #4 Slide Gate | 1101VLV1183B |
Clarifier #4 & #5 Slide Gate | 1101VLV1184B |
Clarifier #5 & #2 Slide Gate | 1101VLV1185B |
Primary Clarifier #1 Channel Influent Valve South | 1101VLV1181 |
Primary Clarifier #1 Channel Influent Valve North | 1101VLV1181A |
Primary Clarifier #2 Channel Influent Valve South | 1101VLV1182 |
Primary Clarifier #2 Channel Influent Valve North | 1101VLV1182A |
Primary Clarifier #3 Channel Influent Valve South | 1101VLV1183 |
Primary Clarifier #3 Channel Influent Valve North | 1101VLV1183A |
Primary Clarifier #4 Channel Influent Valve South | 1101VLV1184 |
Primary Clarifier #4 Channel Influent Valve North | 1101VLV1184A |
Primary Clarifier #5 Channel Influent Valve South | 1101VLV1185 |
Primary Clarifier #5 Channel Influent Valve North | 1101VLV1185A |
Primary Clarifier Sludge Collector Drive #1 | 1101MTR1721 |
Primary Clarifier Sludge Collector Drive #2 & #3 | 1101MTR1722 |
Primary Clarifier Sludge Collector Drive #4 & #5 | 1101MTR1723 |
Primary Clarifier Scum Collector Drive #1 | 1101MTR1724 |
Primary Clarifier Scum Collector Drive #2 & #3 | 1101MTR1725 |
Primary Clarifier Scum Collector Drive #4 & #5 | 1101GBX1726 |
Clarifier #1 Actuated Valve – Sludge Transfer | 1102OPS1677 |
Clarifier #1 Actuated Valve – Sludge Transfer | 1102OPS1677A |
Clarifier #2 Actuated Valve – Sludge Transfer | 1102OPS1677B |
Clarifier #2 Actuated Valve – Sludge Transfer | 1102OPS1677C |
Clarifier #3 Actuated Valve – Sludge Transfer | 1102OPS1677D |
Clarifier #3 Actuated Valve – Sludge Transfer | 1102OPS1677E |
Clarifier #4 Actuated Valve – Sludge Transfer | 1102OPS1677F |
Clarifier #4 Actuated Valve – Sludge Transfer | 1102OPS1677G |
Clarifier #5 Actuated Valve – Sludge Transfer | 1102OPS1677H |
Clarifier #5 Actuated Valve – Sludge Transfer | 1102OPS1677I |
Clarifier #1 – South Drain Plug Valve | 1102VLV1679 |
Clarifier #1 – North Drain Plug Valve | 1102VLV1679A |
Clarifier #2 – South Drain Plug Valve | 1102VLV1679B |
Clarifier #2 – North Drain Plug Valve | 1102VLV1679C |
Clarifier #3 – South Drain Plug Valve | 1102VLV1679D |
Clarifier #3 – North Drain Plug Valve | 1102VLV1679E |
Clarifier #4 – South Drain Plug Valve | 1102VLV1679F |
Clarifier #4 – North Drain Plug Valve | 1102VLV1679G |
Clarifier #5 – South Drain Plug Valve | 1102VLV1679H |
Clarifier #5 – North Drain Plug Valve | 1102VLV1679I |
Primary Sludge Transfer Pump #1 | 1102PMP1100 |
Primary Sludge Transfer Pump #1 – Suction Transfer Valve | 1102VLV1100 |
Primary Sludge Transfer Pump #1 – Discharge Transfer Valve | 1102VLV1100A |
Primary Sludge Transfer Pump #1 – Suction Drain Valve | 1102VLV1679J |
Primary Sludge Transfer Pump #1 – Discharge Drain Valve | 1102VLV1100D |
Primary Sludge Transfer Pump #2 | 1102PMP1200 |
Primary Sludge Transfer Pump #2 – Suction Transfer Valve | 1102VLV1200 |
Primary Sludge Transfer Pump #2 – Discharge Transfer Valve | 1102VLV1200A |
Primary Sludge Transfer Pump #2 – Suction Drain Valve | 1102VLV1679K |
Primary Sludge Transfer Pump #2 – Discharge Drain Valve | 1102VLV1200D |