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Figure 1 - Pond Treatment System Basic Flow Reference Diagram

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Turk Pond Water Treatment System Description

NOTE: Figure 1 can be referenced to provide an elementary flow path for the Pond Water Treatment System. Additionally the following flow diagrams can be referenced for specific information:

Flow Diagram Description

1-51WW001 COAL PILE RUNOFF POND 1-51WW002 PROCESS WATER POND 1-51PW004 POTABLE WATER 1-51SW011 SERVICE WATER 1-51QW010 LAMELLA SETTLERS 1-51QW011 THICKENER, FILTER PRESS 1-51QW012 EFFLUENT TANK, PUMPS 1-51QW013 BACKWASH, RINSE WATER TANK 1-51QW014 BACKWASH AND RINSE PIPING 1-51QW015 MULTI MEDIA FILTERS 1-51QW016 MULTI MEDIA FILTERS 1-51QW017 MULTI MEDIA FILTERS 1-51QW019 FLOCCULENT PUMPS

1. Introduction

1.1. Purpose

The coal pile run-off pond (CPRP) and process water pond (PWP) discharge water treatment system is intended to reduce total suspended solids (TSS) to the levels required for discharging to internal outfalls 201 and 101 respectively. This is accomplished through supplemental treatment to achieve the required TSS reductions and simultaneously manage water inventory. The CPRP discharge treatment system consists of coagulation, flocculation, settling through a Lamella clarifier, and finally filtration. The PWP discharge treatment system consists of filtration only.

Typical operation of the CPRP is to provide storage (surge) capacity during rain events, such that the treatment system is not overburdened. Routine management of CPRP water levels are to ensure that free storage volume is readily available to hold run-off water from major rain events. Thus CPRP levels must be maintained at as low a level as possible (ideally empty) at all times (when practical) by discharging to the PWP, or when necessary to outfall 201. Therefore utilization of the treatment system at the start of all significant / measurable rain events, providing the required TSS reduction, must be implemented to ensure that the CPRP provides

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ample retention for subsequent major rain events and prevents the need for any potential discharge to outfall 002 or exceedences of outfall 201’s TSS limits.

Typical operation of the PWP is to supply and store water to and from plant process water users / contributors as needed. The PWP also provides surge capacity, though it is intended to operate as a net consumer of water, without the need for surplus discharge to control pond levels. However should excess PWP influent(s) ultimately require discharge to outfall 101 to manage pond levels; this flow is treated with multi-media filtration (MMF) for TSS removal to prevent exceedences of outfall 101’s TSS limits.

The treatment system for both internal outfalls (101 and 201) is combined and share common multi-media filtration equipment that can only be used for treatment of one pond waters at a time. The options to manage CPRP and/or PWP discharge within the treatment system are determined / selected based on several operational factors and provide the functionality to support the three following scenarios:

1) Treatment of CPRP discharge only 2) Treatment of PWP discharge only 3) Simultaneous treatment of both CPRP and PWP discharge

Additionally, within these three treatment scenarios, subsequent options exist for the treated effluent location of the pond(s) discharge and/or processing steps. These include the following:

Treatment of CPRP discharge only

A) For routine management of CPRP levels, CPRP discharge is sent through the Lamella clarifiers followed by multi-media filtration, with the final treated effluent directed into the PWP. This provides a high quality effluent for supplemental PWP make-up while managing CPRP levels. This option is available provided the PWP levels are low enough to accept this effluent. Based upon the overall system design (subsequently described) this treatment option is suggested for CPRP discharge flow rates ranging from 100 to 400 gpm.

B) For CPRP discharge treatment rates greater than 400 gpm that are used to supply supplemental make-up water to the PWP; the option available is to send the Lamella effluent directly to the PWP. This is accomplished by a controlled overflow of the Lamella effluent storage tank, which is directed into the PWP. This also provides a relatively high quality make-up water to the PWP, though it may be slightly higher in TSS than a filtered effluent.

C) If the level in the PWP becomes/is too high to accept treated CPRP discharge or if a decision is made to select this effluent destination, the treated water can be directed into the make-up water pond (MWP) through outfall 201 to control CPRP levels. With this option the CPRP discharge is treated through the Lamella clarifiers, then the following options are available to send the Lamella effluent to the MWP:

a. Further treatment with multi-media filtration, provided the filters are not treating PWP discharge and are available, sending the filtered effluent to outfall 201. This is the recommended treatment for flow rates up to 550 gpm.

b. Directing the Lamella effluent storage tank into outfall 201. This option is available if the multi-media filters are unavailable and/or when flow rates exceed 550 gpm.

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c. Any flow rate combinations of the two previously described options (a. and/or b.), depending on equipment availability (filters) and/or the total CPRP discharge flow rates required to manage CPRP levels. The two treated effluents are combined prior to the 201 outfall and sent to the MWP.

Treatment of PWP discharge only

Treatment of surplus PWP discharge is accomplished by multi-media filtration only. A portion of the PWP sump pump discharge is directed through the multi-media filters at a nominal designed flow rate of 300 gpm. Filtered effluent is combined with cooling tower blowdown through outfall 101 and ultimately sent into the waste water pond (WWP).

Simultaneous treatment of both CPRP and PWP discharge

With simultaneous treatment of both pond discharges; the multi-media filters can only treat discharge from the PWP. Therefore, PWP treatment proceeds as previously summarized, through the multi-media filters into internal outfall 101. Discharge from the CPRP is treated thought the Lamella clarifiers and is pumped from the Lamella effluent storage tank to the MWP through internal outfall 201.

The pond treatment system is sized based on historic rain event data to provide an adequate treatment rate, storage volume for routine rain events, and historically frequent major rain events. However, atypical high frequency major rain events may exceed the design flow of the treatment system. These rare instances are outside of the design basis and in order to quickly regain the surge capacity of the CPRP and prevent a discharge to external outfall 002, the CPRP is pumped directly to the MWP, thought internal outfall 201, via the (treatment system) bypass line. If bypassing the CPRP discharge treatment system is necessary, the TSS could be in excess of outfall 201’s permit limits, though a discharge to outfall 002 would be avoided.

2. Design Basis

2.1. CPRP Design Basis and Operation

The CPRP is sized to provide storage of rain water run-off from a 25 year rain event, approximately 9 million gallons of water. In order to maintain and restore the pond’s storage capacity from routine rain events, two sets of pumps are employed. Normal operation is with two 100% low-flow pumps each rated at approximately 200 gpm, pumping to the treatment system and into the PWP. For management of extreme rain events or emergency circumstances, two 50% high-flow pumps each rated at 3,350 gpm discharges into the plant’s MWP via a dedicated 20-inch line. To protect the integrity of the pond walls, the pond also employs an overflow weir that discharges to Bridge Creek (waters of the State), through external outfall 002.

NOTE: Any operation of the high flow pumps, bypassing the treatment system and discharging to the MWP, and/or weir overflows to outfall 002 are only employed to manage extreme and/or emergency situations. These are not anticipated to occur and are not considered standard operation.

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2.2. TSS Management – PWP and CPRP

The objective of the pond treatment system is to reduce the TSS levels in the CPRP and PWP discharge water to less than 30 mg/L. This level of TSS ensures that the permit limit for both internal outfalls, which is 30 mg/L monthly average, and 50 mg/L daily maximum, are met.

Empirical testing has demonstrated that the required TSS reduction of the CPRP discharge is achieved by a combination Lamella clarifier followed by a multi-media filter (MMF) system. Similarly, multi-media filtration alone has demonstrated the required TSS reduction for treatment of PWP discharge.

2.3. Water Treatment System Capacity

Evaluations of historical rainfall data for the region assessed the likely outcomes of varying capacities of CPRP discharge treatment systems. The analysis assumed that at the onset of a significant / measureable / typical rainfall event, defined as a rain event with rainfall totals below the 25 year rain event, plant personnel would initiate operation of the CPRP water treatment system, discharging to the PWP or when necessary to outfall 201. This is to ensure adequate pond inventory for storage of major rain event(s) run-off water, defined as a rain event with rainfall totals up to the 25 year rain event. Continuing/continuous and/or increasing rainfall in excess of the 25 year rain event and/or with events occurring at un-historically high frequencies, the design basis of the CPRP discharge treatment system’s pond inventory management capacity would be exceeded. In these instances where the CPRP level would reach six inches below the overflow weir to outfall 002, the existing high flow pumps would be placed in service thus bypassing the water treatment system. This condition is termed a “Bypass Event”, and under such a situation the 6,700 gpm high-flow pumping system, discharging to the MWP, would keep the pond from overflowing into outfall 002. This prevents a CPRP discharge to an external outfall. However the TSS levels in the bypass line exceeding the plant’s discharge permit limits, established for internal outfall 201, would be a highly probable outcome. Additionally, despite the designed capacity of the high-flow pumps to prevent weir overflows, extreme rainfall events, beyond what can be anticipated based on the available historical rainfall data analyzed, may not preclude a weir overflow (discharge to 002). Given the pond’s poor settling characteristics, in such an extreme situation, external outfall 002 would most certainly experience a permit TSS exceedence.

Based on this prefaced design philosophy and historical rain fall data analysis, a nominal 800 gpm Lamella clarification system, which is the main component for suspended solids removal in the CPRP discharge, was selected. This design treatment rate, based on the historical data analysis, would prevent CPRP weir overflow events; provided extreme rainfall events are not encountered. Two 50% capacity Lamella clarifiers (each rated at a nominal flow of 400 gpm) provide treatment of CPRP discharge to meet the nominal 800 gpm design criteria.

The MMF is provided based upon the filtration capacity needs for the PWP as part of a prior engineering study. As such, the MMF is a 3 x 50% triplex system, designed to treat a nominal 300 gpm (each filter is rated at a 150 gpm nominal capacity) with a maximum of 550 gpm. The triplex filtration system allows for one filter vessel to be backwashed online while maintaining a nominal flow of 300 gpm through the other two vessels.

When the MMF is configured for CPRP treatment where it provides final polishing of the Lamella effluent, the total effluent flow from the Lamella can/will be in excess of the designed nominal filter capacity. Under these conditions, the excess Lamella effluent flow is combined

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with the filtered water. The TSS of the combined waters is anticipated to be below the 201 outfall limit, though it will be tested to confirm this prior to discharging to the 201 outfall. Additional capacity may be available within the MMF system that may allow the treatment system to operate without a direct flow of Lamella effluent to the 201 outfall; however it will depend on the effluent quality of the Lamella as well as further onsite testing to confirm higher flow rates through the MMF will be acceptable. In either case when the MMF is utilized for CPRP treatment the designed filtration system redundancy is compromised.

3. Equipment Descriptions

3.1. Coal Pile Runoff Pond Pumping and Piping to Lamella Influent Mix Tanks / Clarifiers

3.1.1. The CPRP low flow pumps (1PP-WW0210/WW0220) are each rated at 200 gpm at 130’ TDH with a maximum flow capability of 395 gpm at 85’ TDH. This allows for approximately 790 gpm of total influent flow to the Lamella clarifiers.

3.1.2. The low flow pumps are direct drive utilizing a nominal 20 HP motor.

3.1.3. The low flow pump discharge feeds are re-directed to the 20-inch high flow pump (1PP- WW0110/WW0120) discharge line which is branched off via an 8-inch line to the inlet of the Lamella influent mix tanks. The low flow pump discharge also feeds an alternate line for coal yard water users (a future installation/usage based on plant assessment).

3.1.4. At the take-off location of the 8-inch feed line to the Lamella influent mix tanks a 20-inch isolation valve (1HV-WW4403) is placed just downstream to prevent untreated flow from going to the MWP (201 outfall). The associated 8-inch return line (treated water) from the CPRP treatment system is tied back into the same 20-inch line just downstream of the 20-inch isolation valve. The official 201 outfall TSS sample location (1HV- WW4603) is on the 8-inch return line, inside the pond treatment building, downstream of the 8-inch MMF common outlet line and Lamella effluent feed tie point.

3.1.5. A pressure transmitter (1PIT-WW9400) is located on the CPRP low flow pump common discharge header.

3.1.6. Two vee-ball style control valves (1RV-QW0112/1RV-QW0122) controls the flow independently to each Lamella clarifier trains. This allows for independent Lamella clarifier train operation.

3.1.7. The CPRP low flow pumps are operated as follows.

3.1.7.1. One pump is in service with the second pump in automatic standby.

3.1.7.2. The flow control valves to each Lamella clarifier train are automatically adjusted to maintain a flow rate set point based on feedback from each trains inlet flow transmitter (1FIT-QW0112/1FIT-QW0122). Each flow control valve controlling flow to the Lamella train fail/trip in the closed position.

3.1.7.3. The flow transmitters’ signal to the Lamella trains also controls the speed of the coagulant and flocculent chemical injection pumps to maintain respective dosage set points.

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3.1.7.4. Due to high velocities expected when the low flow pump is operated at the end of its curve, mitigation of this potential is accomplished by starting the standby pump when the total Lamella clarifier influent flow rate set point is above 300 gpm or when header pressure drops below 40 psig.

3.1.7.5. Provision are incorporated in the plant DCS logic to allow the use of one high flow pump (1PP-WW0110/1PP-WW0120) in place of the low flow pumps at total Lamella clarifier influent flow rates greater than 550 gpm.

3.1.8. Coagulant Feed (1SK-QW4100)

A coagulant feed, common to both Lamella trains, is injected upstream of two inline static mixers in the common 8-inch influent line prior to branching off to each individual influent mix tank. The total flow signal from both Lamella train flow transmitters is added to provide the total inlet flow signal that is used to pace the coagulant feed for the CPRP treatment system. There are 2 x 100% coagulant injection pumps, one duty and one standby. Estimated (average) dosage is approximately 50 ppm of an aluminum based coagulant.

PLC values used for flow pacing of the coagulant feed are:

User input values at PLC HMI Reference Variable

Coagulant dose (ppm) C_D

Coagulant specific gravity (no units) C_SG

Coagulant percent solution (%) C_P

Dosing pump output at 100% speed (ml/min) C_MX

PLC Values From Instrumentation

Lamella Train 1 Influent Flow (gpm) LT1_Q

Lamella Train 2 Influent Flow (gpm) LT2_Q

Dosing Equation [C_Q], (% speed):

(LT1_Q LT2_Q C_D 0.377 100% C_SG C_P C_MX

3.1.9. Sample points with manual isolation valves are located upstream of the coagulant injection point (1HV-QW0100) and downstream of the static mixers on each Lamella train influent line (1HV-QW0510/1HV-QW0520).

3.2. Lamella Influent Mix Tanks (1TK-QW3010/1TK-QW3020).

3.2.1. The Lamella influent mix tanks are each a 108-inch diameter by 120-inch high open top baffled mixing tank. The tanks are equipped with a 1.5 HP, 100 rpm constant speed,

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variable drive, top mounted mixer used for dispersion and mixing of the flocculent with the influent water.

Flocculent is added into each individual Lamella influent mix tank influent line at approximately 1.5 ppm as product. The flocculent is activated in a solution tank through a mix chamber with dilution water provided from the potable water header. Each flocculent feed system consists of 1 neat flocculent feed pump, 1 mixing chamber, 1 prepared solution day tank, and 1 solution (prepared flocculent) feed pump.

Each Lamella inlet flow transmitter provides the signal to an individual flocculent solution feed pump to pace the flocculent feed to each Lamella train independently. There are 2 x 100% flocculent solution feed systems, one dedicated to each Lamella train and one common 1 x 100% “cold” standby, that is a shared standby system with the thickener/filter press flocculent feed skid.

PLC values used for flow pacing of the Lamella flocculent feed are:

User input values at PLC HMI Reference Variable

Flocculent dose (ppm) F*_D

Flocculent percent solution (%) F*_P

Dosing pump output at 100% speed (ml/min) F*_MX

PLC Values From Instrumentation

Lamella Train 1 Influent Flow (1FIT-QW0112, LT1_Q gpm)

Lamella Train 2 Influent Flow (1FIT-QW0122, LT2_Q gpm)

(*) = 1 or 2 depending on Lamella train

Dosing Equation [F*_Q], (% speed – example for Lamella train 1):

LT1_Q F1_D 0.377 100% F1_P F1_MX

3.3. Lamella Clarifiers (1TK-QW3110/1TK-QW3120)

3.3.1. The Lamella clarification process is utilized for the removal of the suspended material (TSS) in the CPRP discharge water. Clarification in general is designed to bind the smaller particles (i.e. coal fines) in the raw (CPRP) water together to produce larger

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particles through coagulation and flocculation. This is accomplished by charge neutralization of the suspended particles through the reaction between the coagulant and the influent water and subsequent agglomeration of these particles together with the addition/aid of a flocculent. With proper contact time and mixing, the influent (smaller) particles will combine in this physical-chemical process to form larger particles with a mass high enough that it will drop out in the clarifier’s settling basin by gravity.

The clarified water (“clear” overflow) should have a significant portion of the influent TSS removed in this process and the suspended material drops out in the settling basin (“sludge” underflow) for disposal.

The Lamella clarification process also utilizes inclined plates within the settling basin to provide a significant increase in surface area compared to traditional clarifiers to enhance settling. The inclined plates decreases the particulate settling distance that needs to occur in the settling basin, allowing for a Lamella clarifier to operate at higher rise rates (velocities) and with a consequential footprint reduction than traditional clarifiers.

3.3.2. The Lamella clarifiers have a nominal minimum flow capacity of 100 gpm and a maximum total flow capacity of 800 gpm (400 gpm per train). Individual Lamella clarifier operating values are:

Nominal Flow (gpm) 400 Maximum Influent TSS (mg/L) 1000 Nominal Effluent TSS (mg/L) 30 – 50 Nominal Underflow Solids (%) 0.2 – 1.0 Surface Rise Rate (gpm/ft 2) 1.7 Plate Area (ft 2) 1884 Plate Area Rise Rate (gpm/ft 2) 0.21 Settling Basin Length (ft) 19.50 Settling Basin Width (ft) 11.75 Nominal Sludge Removal (gpm) 50 Maximum Sludge Removal (gpm) 100

3.3.2.1. The Lamella clarifier treatment system is supplied as a 2 x 50% (2 x 400 gpm) train configuration and consists of 2 inlet flow control valves, 2 inlet flow meters/transmitters, 2 influent (flocculent) mixing tanks, 2 effluent turbidity meters, 2 inclined FRP plate Lamella clarifiers, eight (8) ¾-inch settling basin sludge sample valves, and 4 underflow sludge transfer pumps (each train has a 2 x 100% (2 x 50 gpm) pump configuration).

3.3.3. Effluent discharge from the Lamella clarifier will gravity feed to the Lamella effluent storage tank or the backwash / rinse water storage tank.

3.3.3.1. An automatic control option for the Lamella effluent destination can be done utilizing the online turbidity meter analysis. A high-high turbidity alarm would provide an option for the PLC to automatically shut the block valve feeding the effluent storage tank and open the block valve in the line feeding the backwash / rinse water storage tank.

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3.3.4. The Lamella sludge transfer pumps (sludge underflow) (1PP-QW3111/3112/3121/3122) are each rated at 50 gpm. Each Lamella train has 2 x 100% capacity pumps (total sludge pumping capacity per Lamella train is 100 gpm, system total is 200 gpm). Sludge transfer from the Lamella to the thickener will be done on a timed duration and frequency basis (time the pump is on and time the pump is off) with all parameters adjustable through the PLC HMI. Sludge transfer will depend on the influent solids loading to the Lamella trains and will require operator interaction to optimize and manage this inventory.

3.3.5. A single biocide chemical addition skid (1 x 100% pump) is used for manual, intermittent treatment with biocide (initially sodium hypochlorite) to the flocculent mix tanks to prevent microbiological growth within the system. Treatment with biocide may be done online or offline as necessary.

3.4. Lamella Effluent Storage Tank (1TK-QW3400) and Pump Skid (1PP-QW3410/1PP-QW3420)

3.4.1. The primary function of the Lamella effluent storage tank is to provide storage for MMF backwash influent and rinse water to prevent cross-contamination of PWP water into CPRP water when the MMFs are used for treating Lamella effluent.

3.4.2. Tank capacity is a nominal 30,000 gallons, which supplies the required volume to backwash and rinse one MMF vessel (anticipated backwash volume of 20,250 gallons) without any influent flow to the tank.

3.4.3. Tank level transmitter (1LIT-QW1102) provides the signal for:

3.4.3.1. Permissive to start MMF backwash sequence (set point level above grade, default of 9-feet).

3.4.3.1.1. When discharge from this tank is directed to the MMFs, the tank level is automatically maintained at 9-feet above grade to ensure adequate volume for MMF backwashing.

3.4.3.2. Permissive for Lamella effluent transfer pump operation (minimum set point level above grade).

3.4.3.3. Provide a bias for the Lamella influent flow control valves to prevent a tank overflow by reducing flow rates should tank levels exceed 9-feet above grade.

3.4.4. Discharge pumping consists of 2 x 100% pumps, each rated at 1365 gpm.

3.4.4.1. Pumps are capable of supplying 900 gpm backwash and concurrent influent flow to two MMFs at 400 gpm (one MMF backwashing, two MMFs online processing 400 gpm).

3.4.4.2. Pump minimum flow protection is accomplished using an orifice plate providing sufficient flow, approximately 65 gpm, to prevent the pump(s) from overheating.

3.4.5. There is a turbidity monitor (1AIT-QW1302) on the pump discharge upstream of the recirculation tap-off point.

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3.4.5.1. Turbidity values can be used to direct flow to the backwash / rinse water storage tank on a high-high turbidity alarm.

3.4.6. Direct discharge into the PWP is accomplished through the 10-inch tank overflow line (1QW160).

3.4.7. Discharge into the MMFs is controlled by the MMF outlet flow control valve (1RV- QW0105).

3.4.8. Direct discharge to outfall 201 from the Lamella effluent transfer pumps (through 1RV- QW1802), is only possible provided the TSS sample analysis obtained from sample valve (1HV-QW4600) indicate this is acceptable.

3.4.9. Discharge to the backwash / rinse water storage tank or to the coal pile run-off pond can be done during Lamella startups, to control Lamella effluent storage tank level, or to purge the Lamella effluent storage tank if contaminated.

3.5. Multi Media Filters (MMFs) (1SK-QW3500)

3.5.1. Three (3) 84-inch diameter, 225 psi ASME code stamped MMF vessels provide solids removal for PWP discharge or Lamella clarifier effluent from the CPRP. The MMF system design basis is to treat a nominal 300 gpm of PWP water prior to discharging into the 101 outfall. However due to the anticipated infrequent usage of these filters for this service, they are also set up to provide supplemental TSS removal for the Lamella effluent; providing downstream filtration during periods of un-steady state / transitional conditions, which has been found to be necessary to consistently meet discharge TSS levels for the 201 outfall.

The MMF vessels contain filter media to remove the suspended solids. The media depths in each vessel are 18-inches of anthracite, 12-inches of filter sand, and 6-inches of garnet. MMFs provide deep bed filtration of the suspended solids allowing for staged filtration as each of the media layers provide finer particle filtration as flow moves vertically down the bed. As such, the design of the MMF allows for relatively high filtration rates with less pressure decay than typical single or dual media filtration systems. Solids that accumulate within the media produce head loss (pressure drop/decay from the filter inlet line to the filter outlet line) across the filter bed. Once the head loss through the media is high enough, the filter must be backwashed (reverse flow) at a relatively high rate to remove the accumulated solids and restore the media.

3.5.2. Normal operation, when treating PWP discharge - influent comes from the PWP sump pumps discharge, MMF outlet (filtered discharge) is sent to outfall 101, backwash and rinse water influent is supplied by the PWP sump pumps discharge, and backwash waste and rinse water outlet is sent back to the PWP. A MMF skid outlet turbidity meter is used for indication of outlet quality and should these levels trigger a high-high turbidity alarm during operation, the MMF discharge is automatically directed back to the PWP.

3.5.3. Normal operation, when treating Lamella clarifier effluent - influent comes from the Lamella effluent storage tank transfer pumps, MMF outlet (filtered discharge) is sent to the PWP or when necessary (typically during high PWP levels) discharged to outfall 201, backwash and rinse water influent is supplied from the Lamella effluent storage tank transfer pumps, and backwash waste and rinse water outlet is sent to the backwash / rinse

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water storage tank. A MMF skid outlet turbidity meter is used for indication of outlet quality and should these levels trigger a high-high turbidity alarm when discharging to outfall 201, the MMF discharge is automatically directed to the backwash / rinse water storage tank.

3.5.4. System design uses manual double block and bleed isolation philosophy of the MMF outlet water to maintain isolation of PWP water from CPRP water discharge to outfalls 101 or 201 respectively.

3.5.5. Valve position indication provides permissives for each mode of operation and transitional usage of the MMF system.

3.5.6. Chemical Feed Systems

3.5.6.1. A ½- inch female NPT tap is installed in the filter inlet line for provisions to accommodate a future chemical feed (filter aid) inlet/injection point should it be necessary.

3.5.7. Disinfection

3.5.7.1. Periodic disinfection with a sodium hypochlorite soak and backwashing can be performed if needed. A ¾-inch female NPT connection on the backwash inlet line to each filter vessel is provided to accommodate a periodic injection of sodium hypochlorite. Should disinfection be necessary, the Lamella sodium hypochlorite dosing skid can feed to the injection point. The dosing skid will feed to the injection point by portable hose connections. Once chemicals have been added the vessel can be air mixed, soaked (as/if needed), and backwashed. This is all a manual operation controlled by the User.

3.6. Backwash / Rinse Water Storage Tank (1TK-QW3600) and Pump Skid (1PP-QW3610/1PP- QW3620)

3.6.1. The purpose of the backwash / rinse water storage tank is primarily to temporarily hold the MMF backwash and rinse water when filtering Lamella effluent to prevent solids accumulation in the PWP; the initially designed location for backwash waste. The tank also provides temporary storage for Lamella effluent during upset conditions. This tank provides the normal means of returning waste / upset waters back to the CPRP.

3.6.2. Tank capacity is a nominal 40,000 gallons providing volume to hold 2 MMF vessel backwashes / rinse cycles without effluent flow from the tank. Normal operation with 300 gpm effluent from the tank provides storage capacity for typical MMF backwashing as needed.

3.6.3. Tank level transmitter will provide signal for:

3.6.3.1. Permissive to MMF skid for backwash sequencing of one vessel (set point level above grade, default value of 1-foot 8-inches).

3.6.3.2. Permissive for discharge pump operation (1-foot 6-inches above grade pump trip, 1-foot 8-inches above grade reset).

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3.6.3.3. Level control in the tank is accomplished by a defined set point in the PLC HMI to start and stop the discharge pumps to ensure a maximum free inventory in the tank at all times as practical. Discharge pumps will start at the defined level set point, initially 2-feet 6-inches and will continue to run until the low level set point, initially1-foot 8-inches is achieved. Pumps will remain in automatic standby when discharge flow is not required and will start when the set point value is achieved. PLC automatically will define the Lead/Lag pump operation or can be designated by the User.

3.6.3.4. Auto start and stop of the Lag pump will occur at tank levels of 7-feet 6-inches and 4-feet respectively.

3.6.3.5. Provide an override to close the Lamella influent flow control valves to stop influent flow should the high level alarm be active for a specified amount of time when the system is running in “1 st Stage Startup”.

3.6.3.6. Provide a bias for the Lamella Effluent Tank to Backwash Tank flow control valve (1RV-QW1902) to prevent a tank overflow by reducing flow rates should tank levels exceed the high level set point for a specified amount of time.

3.6.4. When the tank is receiving MMF backwash outlet flow (up to 900 gpm) the Lead pump will start when the level in the tank reaches 1-foot 6-inches (low level trip point)

3.6.5. Discharge pumping consists of 2 x 100% pumps each rated at 315 gpm.

3.6.5.1. Minimum flow protection is achieved by a manual recirculation with an orifice plate.

3.7. Lamella Sludge Thickener (1TK-QW3200)

3.7.1. Partially thickened sludge from the Lamella underflow is sent to the sludge thickener for holding and the continuing thickening necessary prior to feeding the sludge filter press for ultimate disposal / re-application to the coal pile. The sludge thickener is essentially a traditional clarifier without upstream coagulation of the influent. The low rise rates (settling velocities) and high detention time provided in the sludge thickener vessel allow for settling and further thickening of the Lamella sludge to acceptable concentrations for filter press operation. If gravity settling alone does not provide acceptable settling, provisions for a flocculent feed are provided and can be implemented when/if necessary. The solids that settle to the bottom of the thickener vessel are collected in the center, ultimately through a sludge scraper mechanism, and are pumped to the sludge filter press. Overflow from the thickener is sent to the online Lamella influent mix tank(s) or if overflow solids concentrations are excessive to the PWP.

3.7.2. The sludge thickener vessel is a 30-foot diameter, nominal 84,964 gallon steel tank with a 2 x 12 sloped bottom floor used to collect and thicken the settled sludge from the Lamella clarifiers.

3.7.3. FUTURE – Sludge scraper mechanism

3.7.4. 2 x 100% (2 x 50 gpm) air operated diaphragm sludge transfer pumps send settled sludge from each Lamella train underflow to the sludge thickener (4 total pumps, maximum

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sludge pumping capacity is 200 gpm). Sludge concentrations entering the thickener are assumed to be approximately 0.2 – 1.0% solids. Overflow from the sludge thickener is assumed to be less than 50 mg/L TSS. Underflow from the thickener vessels is assumed to be 2 – 5% solids.

3.7.5. The air operated diaphragm pumps are controlled by User adjustable PLC HMI set points defining the pumping duration (minutes pump is on) and dwell/deadband time (minutes pump is off).

3.7.5.1. During normal Lamella clarifier operation, the air operated diaphragm pumps are staged such that only one (total) pump is in operation at a time. Should solids management in the Lamella clarifier settling basin become inadequate with this restriction, an option on the PLC HMI is available to override this and put the Lamella in “high solids” mode, allowing up to 100 gpm of sludge flow out of each Lamella.

3.7.6. Four sample locations are provided on the bottom side shell of the thickener vessel to assess sludge concentrations and bed level.

3.7.7. Sludge level indication instrumentation (1LIT-QW0702) is provided to estimate sludge volume in the thickener vessel.

3.7.8. Flocculent addition is provided if needed to enhance settling. The flocculent is activated in a solution tank through a mix chamber with dilution water provided from the potable water header. Each flocculent feed system consists of 1 neat flocculent feed pump, 1 mixing chamber, 1 prepared solution day tank, and 1 solution (prepared flocculent) feed pump.

Operational feedback from the Lamella sludge transfer pumps (number of pumps in operation and Lamella train pumping to the thickener) provides the signal to the flocculent solution feed pump to pace the flocculent feed to the thickener and opens the appropriate feed inlet valve. The flocculent feed is provided by a 1 x 100% flocculent solution feed system and one common 1 x 100% “cold” standby that is a shared standby system with the Lamella trains’ flocculent feeds. The flocculent system feed piping branches off to the outlet line from each Lamella train sludge transfer pump discharge. The feed line also has a second branch off to provide flocculent for a potential future use to the filter press inlet.

PLC values used for flow pacing of the thickener flocculent feed are:

PLC user input values at the HMI Reference Variable

Flocculent dose (ppm) FT_D

Flocculent percent solution (%) FT_P

Dosing pump output at 100% speed (ml/min) FT_MX

PLC Values

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Lamella Train 1, Transfer Pumps in Operation LT1_STP_ON

Lamella Train 2, Transfer Pumps in Operation LT2_STP_ON

Sludge flow per pump (gpm) S_Q (50 – Normal) (100 – High Solids Mode)

Dosing Equation [FT_Q], (% speed – example for Lamella train 1):

(LT1_STP_ON S_Q FT_D 0.377 100% FT_P FT_MX

3.8. Sludge Filter Press (1FL-QW3000)

3.8.1. A sludge filter press is utilized to de-water the pre-thickened sludge from the thickener for ultimate disposal / re-application on the coal pile. The filter press will provide the means to transform the sludge slurry into a friable solid suitable for transport. The filter cake produced from the filter press is discharged to a roll-off dumpster and filtrate (overflow water) is sent to the effluent storage tank or the PWP. Operation of the filter press is largely accomplished through relays provided in the Siemens control cabinet located on the filter press mezzanine. The User will determine when a filter press run is necessary and will initiate the press sequencing through the PLC HMI. Detailed operating and system descriptions for the filter press are found in the Siemens vendor manuals.

3.8.2. The filter press has a 95 cubic foot capacity and produces approximately 3,200 pounds of a 20% moisture filter cake per run.

3.8.3. Filter press feed pump skid has 2 x 100 % air operated diaphragm pumps each rated from 25 to 175 gpm depending on discharge head pumping thickened sludge (underflow) from the thickener to the press. The PLC controls the operation of these pumps when the press is in operation.

3.8.3.1. Until the sludge scraper mechanism is installed in the thickener, the interim operation of the filter press feed pumps will be automated to continuously recycle sludge within the thickener tank to prevent solids accumulation at potential “dead” zones in the tank when sludge is not being transferred from the thickener to the filter press.

3.8.4. Filtrate water will typically be sent to the Lamella effluent storage tank, though a manual option is available to route filtrate to the PWP.

3.8.5. A pressure transmitter (1PIT-QW0302) on the filter press inlet line provides a signal to pace a future flocculent feed (if found necessary) and provide operation information to the User to evaluate filter press operation.

3.8.6. A locally mounted high pressure washer is available to clean filter press as needed.

3.8.7. Dumping of filter cake is into a roll-off dumpster.

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3.8.8. Center core blow back is sent to the roll-off dumpster.

3.8.9. A provision for a future flocculent addition is provided to improve sludge press operation, should the sludge characteristics change and/or other future operational issues reveal that this may be necessary.

The proposed automated flocculent addition would only feed when the filter press sequence is in “stage 1”. Should an additional flocculent feed be necessary past the “stage 1” sequence, operations would need to set up the flocculent system for a manual addition.

The flocculent is activated in a solution tank through a mix chamber with dilution water provided from the potable water header. Each flocculent feed system consists of 1 neat flocculent feed pump, 1 mixing chamber, 1 prepared solution day tank, and 1 solution (prepared flocculent) feed pump.

Operational feedback from the filter press feed pumps (discharge pressure) provides the signal to the flocculent solution feed pump to pace the flocculent feed to filter press. The flocculent feed is provided by a 1 x 100% flocculent solution feed system, that is shared with the thickener flocculent feed application, and one common 1 x 100% “cold” standby that is a shared standby system with the Lamella trains’ flocculent feeds

PLC values needed for flow pacing of the flocculent are:

PLC user input values at HMI Reference Variable

Flocculent dose (ppm) FT_D

Flocculent percent solution (%) FT_P

Dosing pump output at 100% speed (ml/min) FT_MX

PLC Values

Discharge Pressure (1PIT-QW0302, psig) PR_FPF

(Proposed) Dosing Equation [FT_Q], (% speed):

(-PR_FPF 0.38 92.2 FT_D 0.377 100% FT_P FT_MX

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4. Operation

NOTE: In this section User refers to either plant laboratory or operations personnel

4.1. When flow is anticipated and/or required to discharge from the CPRP and/or PWP to control pond levels, the User begins the process of bringing the treatment system online through the PLC control system interface (HMI)

4.2. User checks the PLC HMI for alarms and/or other issues that would prevent a startup of the system. User clears alarms and/or addresses issues and then begins the process of starting up the system.

4.2.1. Alarms and/or issues that cannot be resolved are communicated to the plant laboratory staff and/or plant management as appropriate and the process to address these items is initiated.

4.3. User designates the treatment mode on PLC HMI “Main Page” from the following options.

4.3.1. CPRP treatment

4.3.2. PWP treatment

4.3.3. Dual treatment (treatment of both CPRP and PWP waters)

4.4. Once a treatment system mode is designated the User then has the option to select the treatment scheme for each mode. The options available are:

4.4.1. CPRP Treatment

4.4.1.1. MMF treatment discharging to the PWP

4.4.1.2. MMF treatment discharging to outfall 201

4.4.1.3. MMF treatment and Lamella effluent combined discharge to outfall 201

4.4.1.4. Lamella effluent direct discharge to PWP

4.4.2. PWP Treatment

4.4.2.1. Discharge to outfall 101

4.4.2.1.1. This is the only option for this treatment mode and is automatically selected when this mode of operation is designated by the User

4.4.3. Dual treatment

4.4.3.1. CPRP discharging to outfall 201, PWP discharging to outfall 101

4.4.3.2. CPRP discharging to PWP, PWP discharging to outfall 101

4.5. CPRP Treatment

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4.5.1. Selecting this option puts the system into CPRP treatment mode.

4.5.2. The PLC HMI displays selections buttons for the User to select one of the following on the “Main Page” to designate the treatment system option:

(1) MMF treatment discharging to the PWP (2) MMF treatment discharging to outfall 201 (3) MMF treatment and Lamella effluent combined discharge to outfall 201 (4) Lamella effluent direct discharge to PWP

NOTE: For discharge of the Lamella effluent tank directly to outfall 201 the User can select the third option and input a MMF maximum outlet flow rate set point (on the HMI “Set Points” screen) to 0 gpm.

NOTE: Prior to a direct discharge of the Lamella effluent tank to outfall 201 a TSS sample analysis is required from the effluent transfer pump discharge sample valve (1HV-QW4600) indicating that the TSS levels are acceptable to discharge to outfall 201. These results must be logged prior to a 201 outfall discharge

Once a treatment option has been designated by the User, the startup process for the Lamella clarifiers can be initiated.

4.5.3. Initial Startup

4.5.3.1. User checks PLC HMI “Main Page” once a treatment option is selected. If the system displays “Ready” this allows User to walk down the system and line-up / confirm any valves, equipment, etc. necessary to bring flow into the treatment system as appropriate for the option selected. System valve line-up for the options presented in section 4.4.1 is provided in section 5.1.

The following process permissives are necessary to display the “Ready” status on the PLC HMI for initial startup in CPRP treatment mode:

Description Tag Number Position/Status

CPRP High Flow Bypass Block Valve 1HV-QW4403 Closed

CPRP Supply to Treatment System 1HV-WW4303 Open Block Valve Treatment System Return to Outfall 1HV-QW4503 Open 201 Header Block Valve

Coagulant Feed System 1SK-QW4100 Ready

Flocculent Feed System 1SK-QW4000 Ready

PWP Sump Discharge to MMF 1HV-QW8000 Closed Double Block A

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Description Tag Number Position/Status

PWP Sump Discharge to MMF 1HV-QW8200 Closed Double Block B MMF Outlet to 101 Outfall Double 1HV-QW7400 Closed Block A MMF Outlet to 101 Outfall Double 1HV-QW7600 Closed Block B

PREREQUISITE: System turbidity meter online, cleaned, calibrated, and ready for service

4.5.3.2. Once the correct flow path (valving) and equipment status is confirmed and logged by the User, the chemical feed systems are checked and the appropriate set points and dosages for coagulant and flocculent are input into the PLC HMI in the “Chemical Feed” page.

4.5.3.3. The User can input a total Lamella clarifier influent flow rate set point or specify individual Lamella train influent set points, in “gpm” into the PLC HMI in the “Lamella” page.

4.5.3.3.1. Inputting a total Lamella clarifier influent flow rate set point, the number of Lamella trains in service is controlled by the PLC under the following ranges:

“Initial” Operation Flow Required # of Range Lamella Trains (gpm) in Service Train-1 Train-2 100 – 200 1 Lead Standby 200 – 800 2 Lead Lag

The PLC will cycle Lamella trains lead-lag-standby designation following each shutdown or they can be designated at the discretion of the User.

4.5.3.3.2. Inputting individual Lamella train influent flow rate set points, each Lamella can operate independently at the flow rates designated by the User.

4.5.3.4. Once the User inputs a Lamella influent flow rate set point greater than 100 gpm, the PLC then moves the system from “Ready” to “1st Stage Startup”. When the system is in “1st Stage Startup”:

4.5.3.4.1. Lamella clarifier effluent water is automatically routed to the backwash / rinse water storage tank.

4.5.3.4.2. Discharge from the backwash / rinse water storage tank is directed to the CPRP.

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4.5.3.4.3. The PLC HMI will display an option to “Move Into 2 nd Stage Startup”

4.5.3.5. Once the User determines that the Lamella clarifier(s) effluent turbidity values (or TSS sample results) observed/obtained from the 8-inch Lamella train overflow lines (Lamella train 1 and 2 turbidity meters and sample point locations 1AIT-QW0512 and 1HV-QW1610, 1AIT-QW0522 and 1HV-QW1620 respectively) indicate it is acceptable to send water to the Lamella effluent storage tank, the User will select “Move Into 2nd Stage Startup”. Initially the User will monitor this process and determine when acceptable turbidity values are achieved and makes the decision to direct flow to the Lamella effluent storage tank. An option for automatic routing of Lamella effluent based on turbidity values is available on the PLC HMI, but should not be implemented until sufficient operation experience with the system is obtained to confirm the turbidity values are acceptable to support this operation.

4.5.3.5.1. If unacceptable Lamella clarifier(s) effluent turbidity continues to where backwash / rinse water storage tank levels continue to increase up to the high level alarm point, this information needs to be communicated to the plant laboratory supervisor and/or plant management as appropriate. If acceptable effluent turbidity values cannot be obtained within a reasonable period of time (such that CPRP levels are at risk of not providing sufficient run-off water volume storage), these individual(s) must then make a decision to continue with treatment or bypass the TSS removal system to manage CPRP levels.

4.5.3.6. Once the system has moved into “2 nd Stage Startup”:

4.5.3.6.1. Effluent/overflow water from the Lamella clarifier(s) is sent to the Lamella effluent storage tank.

4.5.3.6.2. Discharge from Lamella effluent storage tank is routed to the backwash / rinse water storage tank or directly to the CPRP depending on the level in the backwash / rinse water storage tank or at the discretion of the User.

4.5.3.6.2.1. Since flow is not monitored from the Lamella effluent transfer pumps when discharging through the 8-inch line to the backwash / rinse water storage tank, control of these pumps will be based on level control in the Lamella effluent storage tank. The pump will start at a specified tank level and stop at a specified tank level.

4.5.3.6.3. The PLC HMI “Main Page” will display the selection button “Startup Complete – Proceed with Discharge Treatment Option *”

(*) = One of the options presented in section 4.5.2.

4.5.4. To be able to select “Startup Complete – Proceed with Discharge Treatment Option *” the following must be determined and/or confirmed by the User depending on the treatment option selected:

4.5.4.1. For CPRP discharge treatment options (1), (2), or (4) presented in section 4.5.2:

User determines that stable operations and turbidity readings observed from the effluent transfer pump discharge turbidity meter (1AIT-QW1302) and/or bench top

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turbidity analysis have been achieved and are acceptable to complete the startup process. The User logs the operational values (turbidity, flow, etc.) as appropriate and proceeds with one of these operational options.

4.5.4.2. For CPRP discharge treatment option (3) presented in section 4.5.2:

A TSS sample must be obtained and analyzed from the effluent transfer pump discharge sample valve (1HV-QW4600). The results of the TSS analysis must show acceptable levels for continuous discharge into outfall 201; as the MMF system will startup in “Alternate Outlet to PWP/Recirculation” mode such that a combination of MMF outlet flow with the Lamella effluent will not be possible until the MMF system moves from “Alternate Outlet to PWP/Recirculation” to “Discharge” mode. These results are logged and communicated with the plant laboratory supervisor and/or plant management. Once this communication has taken place, the authoritative plant personnel can determine that the system can continue with this treatment option or if alterative operation is needed. If a decision to proceed with alternate operation is made, the User logs this communication and alternate operation is determined by the plant staff as appropriate.

4.5.5. MMF treatment discharging to the PWP:

4.5.5.1. MMF treatment to the PWP is to be the default treatment method utilized for routine CPRP level management. This mode of operation however is constrained by what flow rate the system can continuously manage as the Lamella clarifiers treatment rate could potentially exceed the MMFs treatment capacity, and that pond and tank level management is limited based on the discharge flow rate (return to the CPRP) of the backwash / rinse water transfer pumps. As such, this mode of operation is suggested when routine CRPP level management can be successfully obtained with discharge flow rates (total Lamella influent flow) of less than 400 gpm. Therefore if higher flow rates are necessary to where high pond or tank levels or unacceptable MMF performance is observed at the flow rates necessary for CPRP level management, an alternate treatment mode must be selected. This option can also be used if the Lamella effluent turbidity levels are too high for direct continues discharge to the PWP where accumulation of solids and/or unacceptable water quality would ultimately be detrimental to PWP operation.

4.5.5.2. In this mode of operation:

The Lamella effluent transfer pumps discharge is directed to the MMFs to supply MMF inlet, backwash inlet, and rinse water. Pump discharge is also directed to the backwash / rinse water storage tank when necessary to maintain the flow path through the Lamella clarifier(s) should the MMF outlet flow rate required to maintain the PWP level set point (automatically reduced MMF outlet flow rate) result in high Lamella effluent storage tank levels.

MMF outlet water is directed into the PWP.

MMF backwash outlet and rinse water is directed to the backwash / rinse water storage tank.

The backwash / rinse water storage tank effluent is directed back to the CPRP to

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maintain tank level.

The Lamella influent flow rate is controlled by a User defined flow rate set point, which initially should be less than 400 gpm. Higher flow rates may be possible once additional operation of the system is achieved and it is found that the system can successfully handle the higher flows.

4.5.5.3. The MMF outlet flow control valve (1RV-QW7605) modulates based on two cascading parameters:

NOTE: In this mode of operation it is highly unlikely that low (below 9-feet) Lamella effluent storage tank levels will occur as MMF outlet flow rates should be less than or equal to the total Lamella influent flow. However should the MMF maximum outlet flow rate set point exceed the Lamella influent flow rate (this could be a possibility), the PLC will alarm/alert the User that this is the case.

(2) PWP level (1LT-WW0400A/B) – increasing PWP levels decreases the MMF outlet flow rate to maintain a level set point down to a minimum flow rate of 100 gpm. Should a high level alarm occur in the PWP in this mode of operation the MMF outlet flow control valve will close and will not re-open until a PWP level permissive is activated. Correspondingly falling PWP levels will increase the MMF outlet flow rate up to the maximum MMF outlet flow rate set point, provided Lamella effluent storage tank levels are being maintained accordingly.

4.5.5.4. Once the MMF system is put into operation to treat Lamella effluent water, the MMF system moves into “Alternate Outlet to PWP/Recirculation” mode and remains in this mode when operating within this treatment option.

4.5.5.5. Since the MMF system cannot handle an excessive amount of influent solids without producing terminal headloss rapidly, the MMF inlet turbidity is monitored by a turbidity meter (1AE-QW0305, displayed on / transmitted by 1AIT-QW0305) on the common 6-inch MMF inlet line. If inlet turbidity levels are not acceptable when in service the PLC will issue high and high-high MMF inlet turbidity alarms. A high- high turbidity alarm closes the MMF outlet flow control valve (1RV-QW0105) and requires the User to acknowledge the alarm before the MMFs can be placed back into service. Until the alarm is acknowledged all Lamella effluent flow is sent to the backwash / rinse water storage tank.

4.5.5.6. The Lamella effluent storage tank level is maintained by the MMF outlet flow control valve and the Lamella effluent storage tank to backwash / rinse tank inlet control valve (1RV-QW1902). The PWP level will dictate the MMF outlet flow rate but will be reduced as needed to maintain the Lamella effluent storage tank level.

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Additionally excess influent water (Lamella influent flow minus MMF outlet flow) will be sent to the backwash / rinse water storage tank as needed to maintain level.

4.5.5.7. The backwash / rinse water storage tank level is maintained by pumping back to the CPRP through the backwash / rinse water transfer pumps. The level in the backwash / rinse water storage tank is to be maintained to provide adequate storage for MMF backwash and rinse water. The limitations of these pumps at approximately 300 gpm should not result in accumulation within the tank and maintaining level should not be an issue with Lamella influent flows less than 400 gpm. However should levels in the backwash / rinse water storage tank not permit a MMF backwash sequence when one is called for, the Lamella influent flow rate is automatically decreased until a backwash level permissive in the backwash / rinse water storage tank is achieved. The Lamella influent flow rate set point is resumed once the backwash sequence is complete. Additionally should a high level alarm in the backwash / rinse water storage tank be active for greater than 30-minutes a common alarm is sent to the DCS and informs operations of a flow imbalance issue that will need to be resolved.

4.5.5.8. The PWP level provides the permissive to receive outlet flow from the MMF. A high level (stop MMF outlet flow) in the PWP closes the MMF outlet flow control valve and all Lamella effluent flow is sent to the backwash / rinse water storage tank. If no action is taken by the user on a high PWP level alarm discharge to the PWP thought the MMFs will automatically resume once a level permissive in the PWP (start MMF outlet flow) is met and operation continues as described in section 4.5.5.2. Therefore selecting this mode of operation automatically maintains PWP and CPRP levels.

4.5.6. MMF treatment discharging to outfall 201:

4.5.6.1. MMF treatment to outfall 201 is to be utilized when PWP levels are considered too high to accept continuous CPRP discharge and the discharge rate of CPRP water required to maintain CPRP levels is less than the MMF maximum outlet flow rate.

4.5.6.2. In this mode of operation:

The Lamella effluent transfer pumps discharge is directed to the MMFs to supply MMF inlet, backwash inlet, and rinse water. Pump discharge is also directed to the backwash / rinse water storage tank when necessary to maintain the flow path through the Lamella clarifier(s) should the MMF outlet flow result in high Lamella effluent storage tank levels.

MMF outlet water is directed into the 201 outfall.

MMF backwash outlet and rinse water is directed to the backwash / rinse water storage tank.

The backwash / rinse water storage tank effluent is directed back to the CPRP to maintain tank levels as necessary.

The Lamella influent flow rate is controlled by a User defined flow rate set point, which needs to be less than the MMF maximum outlet flow rate set point. The PLC

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will alarm/alert the User if the Lamella influent flow rate set point is greater than the MMF maximum outlet flow rate set point in this mode of operation.

4.5.6.3. The MMF outlet flow control valve (1RV-QW7605) modulates based on two cascading parameters:

NOTE: In this mode of operation it is highly unlikely that low (below 9-feet) Lamella effluent storage tank levels will occur as MMF outlet flow rates should be less than or equal to the total Lamella influent flow. Should this occur it could be an indication of process control issues and needs to be investigated.

(2) Lamella influent flow rate set point – initial value for the MMF outlet flow rate set point will be equal to this set point value, up to the MMF maximum outlet flow rate set point; provided Lamella effluent storage tank levels are being maintained accordingly.

4.5.6.4. Once the MMF system is put into operation to treat Lamella effluent water, the MMF system moves into “Alternate Outlet to PWP/Recirculation” mode and the startup process is initiated. The User navigates to the “MMF” screen on the PLC HMI to complete the startup process.

4.5.6.5. Since the MMF system cannot handle an excessive amount of influent solids without producing terminal headloss rapidly, the MMF inlet turbidity is monitored by a turbidity meter (1AE-QW0305, displayed on / transmitted by 1AIT-QW0305) on the common 6-inch MMF inlet line. If inlet turbidity levels are not acceptable when in service the PLC will issue high and high-high MMF inlet turbidity alarms. A high- high turbidity alarm closes the MMF outlet flow control valve (1RV-QW0105) and requires the User to acknowledge the alarm before the MMFs can be placed back into service.

4.5.6.6. Once the MMF system is in “Alternate Outlet to PWP/Recirculation” mode for approximately 1 – 2 retention times or until outlet turbidity values read from the turbidity instrument on the common 6-inch filter outlet line (1AE-QW2005, displayed on / transmitted by 1AIT-QW0305) stabilize the inlet pH values are noted and a sample off of the 6-inch common MMF outlet line sample valve (1HV-QW3105) is obtained. The sample is sent to the plant lab for a TSS analysis and the pH value is reported to the plant lab staff. The plant lab will report the result of the TSS analysis to the User. A pH level between 6 and 9 and TSS analysis result less than 30 mg/L is considered acceptable. A pH level greater than 9 or less than 6 is considered unacceptable. A TSS level greater than 30 mg/L is also considered unacceptable, but provisions may allow for TSS levels up to 50 mg/L to be considered acceptable pending plant lab supervisor or management approval and/or review. Any TSS

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analysis results greater than 50 mg/L is considered unacceptable. The results of the analysis are logged by the User.

NOTE: pH control is not part of the CPRP discharge treatment system, however pH limits for the 201 outfall must be in range prior to discharging to the outfall. It is not anticipated that pH will be outside of these limits when treating CPRP discharge, though should this occur, an analysis of the treatment system would need to be performed to evaluate options to control pH appropriately.

4.5.6.7. Acceptable MMF outlet water analysis results allow a User with appropriate PLC security access to place the filter into “Discharge” mode. In “Discharge” mode the MMF outlet water is sent to the 201 outfall and the PLC controls MMF operation per the operational modes described in section 4.9 and the respective PLC set points.

4.5.6.8. The Lamella effluent storage tank level is maintained by the MMF outlet flow control valve and the Lamella effluent storage tank to backwash / rinse tank inlet valve (1RV-QW1902). The Lamella influent flow rate set point will dictate the MMF outlet flow rate but will be reduced as needed to maintain the Lamella effluent storage tank level. Additionally excess influent water (Lamella influent flow minus MMF outlet flow) will be sent to the backwash / rinse water storage tank as needed to maintain level.

NOTE: While unlikely to occur, the functionality to automatically send water from the Lamella effluent storage tank to the backwash / rinse water storage tank remains as a backup to prevent tank overflows, though as stated it primarily would indicate process and /or control issues that need to be investigated.

4.5.6.9. The backwash / rinse water storage tank level is maintained by pumping back to the CPRP from the backwash / rinse water transfer pumps. The level in the backwash / rinse water storage tank is to be maintained to provide adequate storage for MMF backwash and rinse water. Should levels in the backwash / rinse water storage tank not permit a MMF backwash sequence when one is called for, the filter vessel in the backwash queue is placed on hold until a permissive level in the backwash / rinse water storage tank is achieved. If a backwash / rinse water storage tank backwash level permissive is not obtained within 60-minutes, a common alarm is sent to the DCS and informs operations of the issue.

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4.5.7. MMF treatment and Lamella effluent combined discharge to outfall 201:

PREREQUISITE: The TSS of an anticipated combination of MMF outlet water and Lamella effluent must be calculated and the results logged and communicated with the plant laboratory staff and/or plant management as appropriate. The equation to calculate the anticipated combination is as follows and requires TSS analysis from the MMF common outlet sample valve (1HV-QW3105) and the Lamella effluent transfer pump discharge sample valve (1HV-QW4600) and/or individual Lamella train effluent samples.

LETD_TSS sample obtained per section 4.5.4.2

(LETD_TSS LETD_Q* ( MMF_OUT_TSS MMF_OUT_Q BLEND_TSS LETD_Q* MMF_OUT_Q

Where:

LETD_TSS = Lamella effluent transfer pump discharge TSS, mg/L

LETD_Q* = Anticipated Lamella effluent flow to outfall 201, gpm

MMF_OUT_TSS = MMF outlet TSS, mg/L

MMF_OUT_Q = MMF outlet flow rate, gpm

4.5.7.1. MMF treatment and Lamella effluent combined discharge to outfall 201 is to be utilized when PWP levels are considered too high to accept continuous CPRP discharge and the discharge rate of CPRP water required to maintain CPRP levels is greater than the MMF maximum outlet flow rate. Selecting this option requires that a combination of MMF outlet and Lamella effluent water meets the TSS discharge level requirements for the 201 outfall. The combined effluent is sampled at the official 201 outfall sample point (1HV-WW4603).

4.5.7.2. In this mode of operation:

The Lamella effluent transfer pumps discharge is directed to the MMFs to supply MMF inlet, backwash inlet, and rinse water, to outfall 201 through the Lamella effluent transfer pump direct discharge line to outfall 201 (1QW155), and when necessary to the backwash / rinse water storage tank to maintain the flow path through the Lamella clarifier(s) should the total flow to outfall 201 result in high Lamella effluent storage tank levels.

MMF outlet water is directed into the 201 outfall.

MMF backwash outlet and rinse water is directed to the backwash / rinse water storage tank.

The backwash / rinse water storage tank effluent is directed back to the CPRP to maintain tank levels as necessary.

The Lamella influent flow rate is controlled by a User defined flow rate set point.

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4.5.7.3. The MMF outlet flow control valve (1RV-QW7605) modulates based on two cascading parameters:

(1) Lamella effluent storage tank level (1LIT-QW1102) – the PLC is designed to maintain a minimum level of 9-feet in the Lamella effluent storage tank at all times when treating CPRP discharge to provide adequate volume for MMF backwashing. Therefore if the outlet flow rate exceeds the influent(s) to the tank (Lamella effluent flow) the PLC will automatically reduce the MMF outlet flow to maintain the tank level. Should the Lamella effluent storage tank influent(s) exceed the MMF outlet flow rate resulting in increasing tank levels the excess flow is sent to directly to outfall 201. Additionally should the Lamella effluent storage tank levels continue to increase with maximum flow being sent to the MMFs and through the Lamella effluent storage tank direct discharge to outfall 201 the inlet valve the backwash / rinse water storage tank inlet valve (1RV-QW1902) is opened to provide supplemental flow out of the Lamella effluent storage tank to maintain the level.

NOTE: In this mode of operation it is highly unlikely that low (below 9-feet) Lamella effluent storage tank levels will occur as total outlet flow rates should be less than or equal to the total Lamella influent flow. Should this occur it could be an indication of process control issues and needs to be investigated.

(2) Lamella influent flow rate set point – the value for the MMF outlet flow rate set point will be equal to this set point value up to the MMF maximum outlet flow rate set point, provided Lamella effluent storage tank levels are being maintained accordingly. A Lamella influent flow rate set point greater than the MMF maximum outlet flow rate set point will direct the excess flow to outfall 201 and the MMF outlet flow rate will be set to the MMF maximum outlet flow rate set point. Lamella effluent tank level will continue to be maintained as previously described.

4.5.7.4. Once the MMF system is put into operation to treat Lamella effluent water, the MMF system moves into “Alternate Outlet to PWP/Recirculation” mode and the startup process is initiated. The User navigates to the “MMF” screen on the PLC HMI to complete the startup process.

4.5.7.5. Since the MMF system cannot handle an excessive amount of influent solids without producing terminal headloss rapidly, the MMF inlet turbidity is monitored by a turbidity meter (1AE-QW0305, displayed on / transmitted by 1AIT-QW0305) on the common 6-inch MMF inlet line. If inlet turbidity levels are not acceptable when in service the PLC will issue high and high-high MMF inlet turbidity alarms. A high- high turbidity alarm closes the MMF inlet flow control valve (1RV-QW0105) and requires the User to acknowledge the alarm before the MMFs can be placed back into service.

4.5.7.6. Once the MMF system is in “Alternate Outlet to PWP/Recirculation” mode for approximately 1 – 2 retention times or until outlet turbidity values read from the turbidity instrument on the common 6-inch filter outlet line (1AE-QW2005, displayed on / transmitted by 1AIT-QW0305) stabilize the inlet pH values are noted and a sample off of the 6-inch common MMF outlet line sample valve (1HV-QW3105) is obtained. The sample is sent to the plant lab for a TSS analysis and the pH value is reported to the plant lab staff. The plant lab will report the result of the TSS analysis to the User. A pH level between 6 and 9 and TSS analysis result less than 30 mg/L is

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considered acceptable. A pH level greater than 9 or less than 6 is considered unacceptable. A TSS level greater than 30 mg/L is also considered unacceptable, but provisions may allow for TSS levels up to 50 mg/L to be considered acceptable pending plant lab supervisor or management approval and/or review. Any TSS analysis results greater than 50 mg/L is considered unacceptable. The results of the analysis are logged by the User.

4.5.7.7. Acceptable MMF outlet water analysis results allow a User with appropriate PLC security access to place the filter into “Discharge” mode. In “Discharge” mode the MMF outlet water is sent to the 201 outfall and the PLC controls MMF operation per the operational modes described in section 4.9 and the respective PLC set points.

4.5.7.8. The Lamella effluent storage tank level is maintained by the MMF outlet flow control valve, the Lamella effluent transfer pump discharge to outfall 201 flow control valve, and the Lamella effluent storage tank to backwash / rinse tank inlet valve (1RV-QW1902). The Lamella influent flow rate set point will dictate the MMF outlet flow rate as described in section 4.5.7.3 (2), but will be reduced if needed to maintain the Lamella effluent storage tank level. Additionally excess influent water (Lamella influent flow minus MMF outlet flow) will be sent to outfall 201, and if necessary to the backwash / rinse water storage tank to maintain level. Since flow to the backwash / rinse water storage tank is considered an atypical operation, and could be indicative of more fundamental operational issues, the PLC will track how long the backwash / rinse water storage tank inlet valve is open and send a common alarm to the DCS to alert operations of this issue once a User defined time has elapsed

4.5.7.9. The backwash / rinse water storage tank level is maintained by pumping back to the CPRP from the backwash / rinse water transfer pumps. The level in the backwash / rinse water storage tank is to be maintained to provide adequate storage for MMF backwash and rinse water. Should levels in the backwash / rinse water storage tank not permit a MMF backwash sequence when one is called for, the filter vessel in the backwash queue is placed on hold until a permissive level in the backwash / rinse water storage tank is achieved. If a backwash / rinse water storage tank backwash level permissive is not obtained within 60-minutes, a common alarm is sent to the DCS and informs operations of the issue.

4.5.8. Lamella effluent direct discharge to PWP:

4.5.8.1. Lamella effluent discharge to the PWP is to be utilized when CPRP discharge treatment does not require filtration to remove additional TSS and Lamella effluent TSS levels are consistently low enough not to impact PWP operation. In this mode of

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operation the Lamella effluent storage tank high and high-high level alarms are temporarily set to 100% and the Lamella effluent transfer pumps run at minimum flow at 100% recirculation (all discharge valves are closed and water is recirculated through 1QW174). These pumps run in this mode to allow for a continuous turbidity reading on the Lamella effluent transfer pump discharge to monitor effluent quality. In this mode of operation the Lamella effluent storage tank overflows through the 10- inch overflow line (1QW160) into the PWP.

4.5.8.2. The PWP level provides the permissive for this mode of operation. A high level in the PWP opens the inlet valve to the backwash / rinse water storage tank. Discharge to the PWP will automatically resume once a level permissive in the PWP is met and operation continues as described in section 4.5.8.1. Therefore selecting this mode of operation automatically maintains PWP and CPRP levels.

4.5.9. Once CPRP discharge flow is established to the PWP, the MMFs, or into outfall 201, the User checks the sludge transfer pump set points on the PLC HMI and makes appropriate adjustments to these values as needed to initially manage solids inventory within the Lamella.

4.5.10. The PLC controls the Lamella influent flow control valves, the number of Lamella trains in service, chemical feed systems, and sludge transfer pump operation to automatically maintain their respective set points.

4.6. PWP Treatment

4.6.1. Selecting this option puts the system into PWP treatment mode.

4.6.1.1. Discharge to outfall 101 is automatically selected as the operational option.

4.6.2. In this mode of operation:

A portion of the PWP sump pumps discharge is directed to the MMFs to supply MMF inlet, backwash inlet, and rinse water.

MMF outlet water is directed into the 101 outfall.

MMF backwash outlet and rinse water is directed back to the PWP.

MMF outlet flow rate is controlled by a User defined flow rate set point

4.6.3. User checks PLC HMI “Main Page”. If system displays “Ready” this allows User to walk down the system and line-up any valves necessary to bring flow into the treatment system as appropriate for the mode of operation required. System valve line-up is provided in section 5.2.

The following process permissives are necessary to display the “Ready” status on the PLC HMI for initial startup in PWP treatment mode:

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Description Tag Number Position/Status

MMF Outlet to 201 Block Valve-A 1HV-QW7700 Closed Position MMF Outlet to 201 Block Valve-B 1HV-QW7900 Closed Position MMF Outlet to 101 Block Valve-A 1HV-QW7400 Open Position MMF Outlet to 101 Block Valve-B 1HV-QW7600 Open Position PWP Sump Discharge to MMF Block 1HV-QW8000 Open Valve-A PWP Sump Discharge to MMF Block 1HV-QW8200 Open Valve-B MMF Backwash Outlet to BWP Block 1HV-QW5000 Open Valve MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Block 1HV-QW5100 Closed Valve-A MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Block 1HV-QW5100 Closed Valve-A

4.6.4. Once the correct valving is confirmed and logged by the User, the User will define the discharge flow rates from the PWP necessary to manage PWP levels and begin the process of bringing the treatment system (MMFs) online.

PREREQUISITE: Turbidity and pH meter online, cleaned, calibrated, and ready for service

4.6.5. User navigates to the “MMF” screen on the PLC HMI and inputs an appropriate MMF outlet flow rate set point, in “gpm”, necessary to manage PWP levels. Flow is directed to the MMF from the PWP sump discharge header.

4.6.6. The MMF moves into “Alternate Outlet to PWP/Recirculation” mode and the startup process is initiated.

4.6.7. Since the MMF system cannot handle an excessive amount of influent solids without producing terminal headloss rapidly, the MMF inlet turbidity is monitored by a turbidity meter (1AE-QW0305, displayed on / transmitted by 1AIT-QW0305) on the common 6- inch MMF inlet line. If inlet turbidity levels are not acceptable when in service the PLC will issue high and high-high MMF inlet turbidity alarms. A high-high turbidity alarm closes the MMF inlet flow control valve (1RV-QW0105) and requires the User to acknowledge the alarm before the MMFs can be placed back into service.

4.6.8. Once the MMF system is in “Alternate Outlet to PWP/Recirculation” for approximately 1 – 2 retention times or until outlet turbidity values read from the turbidity instrument on

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the common 6-inch filter outlet line (1AE-QW2005, displayed on / transmitted by 1AIT- QW0305) stabilize the inlet pH values are noted and a sample off of the 6-inch common MMF outlet line sample valve (1HV-QW3105) is obtained. The sample is sent to the plant lab for a TSS analysis and the pH value is reported to the plant lab staff and logged. The plant lab will report the result of the TSS analysis to the User (as appropriate). A pH level between 6 and 9 and TSS analysis result less than 30 mg/L is considered acceptable. A pH level greater than 9 or less than 6 is considered unacceptable. A TSS level greater than 30 mg/L is also considered unacceptable, but provisions may allow for TSS levels up to 50 mg/L to be considered acceptable pending plant lab supervisor or management approval and/or review. Any TSS analysis results greater than 50 mg/L is considered unacceptable. The results of the analysis are logged by the User.

NOTE: pH control for the PWP is described in the PWP acid feed system description.

4.6.8.1. If the TSS and/or pH analysis is not acceptable, the User will continue to monitor the outlet turbidity and inlet pH levels with the filter in “Alternate Outlet to PWP/Recirculation” mode and after 30-minutes sampling is repeated. If the second set of TSS sample analysis and/or pH values indicate an unacceptable outlet water quality these results are communicated by the plant lab to the laboratory supervisor and/or plant management as appropriate. These individual(s) must then make a decision to continue to recirculate the filter system or find alternate ways to manage PWP levels.

4.6.9. Acceptable outlet water analysis results allow a User with appropriate PLC security access to place the filter into “Discharge” mode. In “Discharge” mode the MMF outlet water is sent to the 101 outfall and the PLC controls MMF operation per the operational modes described in section 4.9 and the respective PLC set points.

4.6.10. When discharge flow rates to the 101 outfall are anticipated to significantly decrease and/or are no longer necessary the filter can be placed into “recirculation”, “standby”, or “offline” modes as needed.

4.7. Dual treatment (treatment of PWP and CPRP discharge)

4.7.1. Selecting this option puts the system into Dual treatment mode.

4.7.2. The PLC HMI displays selections buttons for the User to select one of the following options on the “Main Page”:

(1) CPRP discharging to outfall 201, PWP discharging to outfall 101 (2) CPRP discharging to PWP, PWP discharging to outfall 101

NOTE: Individual treatment of either CPRP or PWP waters can be accomplished under this mode by inputting flow rate set points to 0 gpm for the respective pond treatment system that is chosen to not be in service.

4.7.3. User checks PLC HMI “Main Page”. If system displays “Ready” this allows User to walk down the system and line-up any valves necessary to bring flow into the treatment system as appropriate for the mode of operation required. System valve line-up is provided in section 5.3.

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The following permissives are necessary to display the “Ready” status on the PLC HMI for Dual treatment mode:

Description Tag Number Position/Status

CPRP High Flow Bypass Block Valve 1HV-QW4403 Closed Position CPRP Supply to Treatment System 1HV-WW4303 Open Block Valve Position Treatment System Return to Outfall 1HV-QW4503 Open 201 Header Block Valve Position

Coagulant Feed System 1SK-QW4100 Ready

Flocculent Feed System 1SK-QW4000 Ready

Lamella Effluent Tank Discharge to 1HV-QW4800 Closed MMF Block Valve-A Position Lamella Effluent Tank Discharge to 1HV-QW4900 Closed MMF Block Valve-B Position MMF Outlet to 201 Block Valve-A 1HV-QW7700 Closed Position MMF Outlet to 201 Block Valve-B 1HV-QW7900 Closed Position MMF Outlet to 101 Block Valve-A 1HV-QW7400 Open Position MMF Outlet to 101 Block Valve-B 1HV-QW7600 Open Position PWP Sump Discharge to MMF Block 1HV-QW8000 Open Valve-A PWP Sump Discharge to MMF Block 1HV-QW8200 Open Valve-B MMF Backwash Outlet to PWP Block 1HV-QW5000 Open Valve MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Block 1HV-QW5100 Closed Valve-A MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Block 1HV-QW5300 Closed Valve-B

4.7.4. Once the correct valving is confirmed and logged by the User, the User will define the discharge flow rates from the PWP and CPRP necessary and begin the process(es) of bringing the treatment system(s) online to treat these flows.

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PREREQUISITE: Turbidity and pH meter online, cleaned, calibrated, and ready for service

4.7.5. CPRP discharging to outfall 201, PWP discharging to outfall 101

4.7.5.1. This mode of operation is to be utilized when both CPRP and PWP levels are high enough that discharge to their respective internal outfalls is necessary to reduce pond levels. This mode of operation would likely be implemented following a major rain event that occurred during a time when PWP usage was minimal (plant outages, etc.).

4.7.5.2. In this mode of operation:

The Lamella effluent transfer pumps discharge is directed to outfall 201 through the Lamella effluent transfer pump direct discharge line to outfall 201 (1QW155).

The Lamella influent flow rate is controlled by a User defined flow rate set point.

A portion of the PWP sump pumps discharge is directed to the MMFs to supply MMF inlet, backwash inlet, and rinse water.

MMF outlet water is directed into the 101 outfall.

MMF backwash outlet and rinse water is directed back to the PWP.

MMF outlet flow rate is controlled by a User defined flow rate set point.

4.7.5.3. CPRP treatment – in Dual treatment mode

4.7.5.3.1. User completes the Lamella initial startup procedure as described in sections 4.5.3.3 through 4.5.3.6.

4.7.5.3.2. Once the system has moved into “2 nd Stage Startup” per section 4.5.3.6, the PLC HMI “Main Page” will display the selection button “Lamella Startup Complete – Proceed with Discharge to Outfall 201”

4.7.5.3.3. For a User with appropriate PLC security access to be able to select “Lamella Startup Complete – Proceed with Discharge to Outfall 201”, a TSS sample must be obtained and analyzed from the effluent transfer pump discharge sample valve (1HV-QW4600). The results of the TSS analysis must show acceptable levels for continuous discharge into outfall 201. These results are logged and communicated with the plant laboratory supervisor and/or plant management. Once this communication has taken place, the authoritative plant personnel can determine that the system can continue with this treatment option or if alterative operation is needed. If a decision to proceed with alternate operation is made, the User logs this communication and alternate operation is determined by the plant staff as appropriate.

4.7.5.4. PWP treatment – in Dual treatment mode

4.7.5.4.1. PWP discharge treatment proceeds per the procedure presented in sections 4.6.5 – 4.6.10.

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4.7.5.5. Since the Lamella effluent and backwash / rinse water storage tanks are not necessary for MMF backwashing, control of their respective transfer pumps will be based on tank levels. The pump will start and stop at specified tank levels.

4.7.6. CPRP discharging to PWP, PWP discharging to outfall 101

4.7.6.1. CPRP discharging to the PWP when in dual treatment mode is provided for added flexibility in the system. However this option should be very seldom used and primarily is only included if there were issues with the performance (high TSS) of the Lamella that prevented discharge into outfall 201 and discharge from the CPRP was necessary to maintain pond levels.

4.7.6.2. PWP treatment would proceed as described in section 4.7.5.4.

4.7.6.3. In this mode of operation the Lamella effluent storage tank high and high-high level alarms are temporarily set to 100% and the Lamella effluent transfer pumps run at minimum flow at 100% recirculation (all discharge valves are closed and water is recirculated through 1QW174). These pumps run in this mode to allow for a continuous turbidity reading on the Lamella effluent transfer pump discharge to monitor effluent quality.

4.7.6.4. The PWP level provides the permissive for this mode of operation. A high level in the PWP sends a common alarm to the DCS and opens the inlet valve to the backwash / rinse water storage tank.

4.8. MMF Operation When Switching Between CPRP and PWP Treatment Modes

Presently a discharge of PWP water into CPRP water is not allowed due to the design of the plant pond system outfalls and permit limitations. To prevent this from occurring when transitioning the MMFs from CPRP treatment (Lamella effluent water) to and from PWP treatment the following procedural summary must be followed.

4.8.1. Initial and/or transitional use of the MMFs from PWP filtration to CPRP treatment:

4.8.1.1. All MMF vessels are to be backwashed with backwash inlet supplied by the Lamella effluent transfer pumps.

4.8.1.2. Backwash outlet is directed to the PWP.

4.8.1.3. Rinse water is supplied by the Lamella effluent transfer pumps.

4.8.1.4. Rinse water outlet is directed to the PWP.

4.8.1.5. Following the completion of the backwash sequencing of all of the MMF vessels, MMF inlet is supplied by the Lamella effluent transfer pumps.

4.8.1.6. Filter outlet is directed to the PWP for a minimum of 2 vessel retention times.

4.8.1.7. Once 2 vessel retention times are met, filter outlet can be directed to the 201 outfall if necessary.

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4.8.1.8. Continuing MMF operation is summarized as:

4.8.1.8.1. MMF inlet is supplied by the Lamella effluent transfer pumps.

4.8.1.8.2. MMF backwash inlet is supplied by the Lamella effluent transfer pumps.

4.8.1.8.3. MMF backwash outlet is directed to the backwash / rinse water storage tank.

4.8.1.8.4. MMF rinse water is supplied by the Lamella effluent transfer pumps.

4.8.1.8.5. MMF rinse water outlet is directed to the backwash / rinse water storage tank.

4.8.2. Initial and/or transitional use of the MMFs from CPRP treatment to PWP filtration:

4.8.2.1. No special procedure is necessary as CPRP discharge to the PWP is allowed. Operation is standard as follows:

4.8.2.1.1. MMF inlet is supplied by the PWP sump pumps

4.8.2.1.2. MMF outlet is directed to the PWP/101 outfall (recirculation/discharge)

4.8.2.1.3. MMF backwash inlet is supplied by the PWP sump pumps.

4.8.2.1.4. MMF backwash outlet is directed to PWP.

4.8.2.1.5. MMF rinse water is supplied by the PWP sump pumps.

4.8.2.1.6. MMF rinse water outlet is directed to the PWP.

4.9. MMF Operational Modes Summary

4.9.1. “Discharge”

PREREQUISITE: MMF system outlet TSS sample has been analyzed by the lab and it is less than 30 mg/L and inlet pH levels are between 6 to 9. An outlet TSS sample result up to 50 mg/L may allow the filters to be placed into “discharge” mode however it requires approval from plant laboratory supervisor and/or management.

4.9.1.1. MMF outlet is discharged to the 101 or 201 outfall as specified by the User depending on the mode of operation (“PWP” or “CPRP” treatment modes respectively).

4.9.1.2. MMF outlet flow rates when treating Lamella effluent water vary depending on the operational option selected but are firstly based on maintaining a level in the Lamella effluent storage tank to provide adequate volume for backwashing. MMF outlet flow rates when treating PWP discharge are controlled by a User input set point in “gpm” into the PLC HMI. The filter outlet flow control valve (1RV-QW0105) located on the common MMF inlet line modulates based on feedback from the MMF outlet flow meter (1FE-QW2105) on the common MMF outlet line to maintain the MMF outlet flow rate set point.

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4.9.1.3. The number of filter vessels in service is controlled by the PLC under the following ranges:

“Initial” Vessel Operation Flow Required # Range of Filters in (gpm) Service 1 2 3 100 – 175 1 Lead Standby-A Standby-B 175 – 300 2 Lead Lag-A Standby-A 300 – 550 3 Lead Lag-A Lag-B

The PLC will cycle filter vessels in service following backwashing and/or based on a User input time to ensure filters do not stagnate and/or have excessive service time.

Individual vessel flow rates are determined by a division of the total flow indicated on the outlet flow meter by the number of vessels in service.

4.9.1.4. Backwashing is controlled by the PLC and can be automatically initiated based one of the following:

1) Outlet turbidity set point 2) Single filter vessel influent to effluent differential pressure set point 3) Single vessel throughput 4) Time based 5) Manually initiated by the User

4.9.1.4.1. Automatic initiation of backwashing can be disabled by the User on the PLC HMI “MMF” screen. If automatic initiation of backwashing is disabled the backwash conditions described in section 4.9.1.4 remain active and will “lock” the filter out of service rather than initiating a backwash sequence. The User will need to manually initiate a backwash sequence in order to put the vessel back into service.

4.9.2. “Alternate Outlet to PWP/Recirculation”

4.9.2.1. MMF outlet is directed to the PWP through the branch line off of the MMF outlet header to the trench drain.

4.9.2.2. MMF alternate outlet/recirculation flow rates when treating Lamella effluent water vary depending on the operational option selected but are firstly based on maintaining a level in the Lamella effluent storage tank to provide adequate volume for backwashing. MMF alternate outlet/recirculation flow rates when treating PWP discharge are controlled by a User input set point in “gpm” into the PLC HMI. The filter outlet flow control valve (1RV-QW0105) located on the common MMF inlet line modulates based on feedback from the MMF outlet flow meter (1FE-QW2105) on the common MMF outlet line to maintain the MMF outlet flow rate set point.

4.9.2.3. The number of filter vessels in service is controlled by the PLC under the following ranges:

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“Initial” Vessel Operation Flow Required # Range of Filters in (gpm) Service 1 2 3 100 – 175 1 Lead Standby-A Standby-B 175 – 300 2 Lead Lag-A Standby-A 300 – 550 3 Lead Lag-A Lag-B

PLC will cycle filters vessels in service following backwashing and/or based on a User input time to ensure filters do not stagnate and/or have excessive service time.

Individual vessel flow rates are determined by a division of the total flow indicated on the outlet flow meter by the number of vessels in service.

4.9.2.4. Backwashing is controlled by the PLC and can be automatically initiated based one of the following:

1) Outlet turbidity set point 2) Single filter vessel influent to effluent differential pressure set point 3) Single vessel throughput 4) Time based 5) Manually initiated by the User

4.9.2.4.1. Automatic initiation of backwashing can be disabled by the User on the PLC HMI “MMF” screen. If automatic initiation of backwashing is disabled the backwash conditions described in section 4.9.2.4 remain active and will “lock” the filter out of service rather than initiating a backwash sequence. The User will need to manually initiate a backwash sequence in order to put the vessel back into service.

4.9.3. “Standby”

4.9.3.1. Filters are not receiving or discharging flow

4.9.3.2. PLC is active and filters are backwashed automatically with PWP water based on a User input time. Backwash discharge is directed back to the PWP. The PLC will cycle filter vessel backwashing to ensure filters do not stagnate and/or have excessive idle time.

4.9.4. “Offline”

4.9.4.1. Filters are not receiving or discharging flow

4.9.4.2. PLC is active and filters are backwashed manually with PWP water by the User. Backwash discharge is directed back to the PWP. The PLC will not cycle filter vessel backwashing. User will need to manage filter out-of-service time and backwash appropriately to ensure filters do not stagnate and/or have excessive idle time. PLC will continue to be utilized to perform the backwash sequencing.

4.9.5. Backwashing

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4.9.5.1. Backwashing of the MMF is necessary to remove the solids that have accumulated within the filter bed over the service run. Excessive solids accumulation on the filter media results in headloss across the vessel(s) and/or poor filter outlet quality.

Backwashing involves primarily an air scour, backwash to achieve a 30 – 50% media bed expansion, and a rinse down step. Only one filter vessel is allowed to backwash at a time and a filter cannot be backwashed when the MMFs are in “Alternate outlet to PWP/Recirculation” mode. If the MMF system is running in “Alternate outlet to PWP/Recirculation” and a backwash of one of the vessels is necessary, backwashing will take priority and MMF outlet flow is temporarily suspended during the backwash sequence when backwash outlet flow is discharged from the vessel. If more than one filter requires a backwash per one/multiple triggers of the presented options/trip points, it will be queued and is backwash based on its place in the queue. Queue priorities are: Lead, Lag-A, Lag-B, Standby-A, Standby-B.

NOTE: All backwash “trigger” set points for the items listed in sections 4.9.1.4 and 4.9.2.4 will have initial values but primarily will be determined upon commissioning and/or adjusted over time as needed.

NOTE: All backwash “sequencing”, timing, and other applicable set points will have initial values but primarily will be determined upon commissioning and/or adjusted over time as needed.

4.9.6. Backwash permissives

4.9.6.1. CPRP treatment mode:

Description Tag Number Position/Status

9-ft or set point Lamella Effluent Storage Tank Level 1LIT-QW0102 value Backwash / Rinse Water Storage Tank 1-ft 8-in or set 1LIT-QW0202 Level point value

4.9.6.2. PWP or Dual treatment mode(s):

Description Tag Number Position/Status

1LT- Greater than set PWP Level WW0400A/B point value MMF Backwash Outlet to BWP Block 1HV-QW5000 Open Valve MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Block 1HV-QW5100 Closed Valve-A MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Block 1HV-QW5300 Closed Valve-B

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4.9.7. Backwash sequencing

NOTE: Time ranges are estimates; initial values will be determined following commissioning.

Step Process Time Purpose 1 Drain Down TBD Provide void space for air scour in the top of the vessel 2 Air scour 5 – 15 min. Agitate media and loosen sediment in media layers 3 Settle 3 – 10 min. Allow media to settle back in filter vessel 4 Refill TBD Prevents air surge / hammer prior to backwashing 5 Backwash 10 – 30 min. Remove sediment from filter media 6 Settle 3 – 10 min. Allow media to re-classify 7 Rinse TBD Allow filter effluent quality to stabilize

Backwash steps can also be held or adjusted at any time during the backwash sequence by the User through the PLC HMI should it seem that additional time is needed for a particular step. The backwash sequence can also be stopped at any time and restarted or reset as appropriate.

A low backwash flow alarm set point is active during the backwash step (step 5) (initially < 400 gpm) that stops the backwash sequence and restarts step 5 after a 10- minutes. If (3) restarts are encountered during a single vessel backwash sequence this filter vessel is “locked” out of service until a complete backwash sequence can be performed. A common trouble alarm is sent to the DCS.

4.9.8. Backwash steps

4.9.8.1. Backwash air scour

4.9.8.1.1. Air flow for the air scour step is required at approximately 200 cfm at 7 – 8 psi. Air flow is supplied from the 2-inch air scour inlet line. Air flow is introduced for approximately 5 – 15 minutes and is User adjustable on the PLC HMI. Air flow through the MMF vessel during the air scour is vented to atmosphere.

4.9.8.2. Backwash flow

4.9.8.2.1. Backwash water is introduced through the common MMF backwash inlet line at 400 – 900 gpm to achieve a 30 – 50% media bed expansion. Media expansion during backwashing can be observed through the upper sight glass on the side of the filter vessel. If proper media expansion is not observed during backwashing the backwash inlet flow can be increased by changing the set point on the PLC HMI as needed. If proper media expansion is not observed up to the maximum flow rate of 900 gpm the filter may be experiencing mechanical issues.

Backwash water is fed to the MMF system through the 8-inch discharge line off of the Lamella effluent transfer pumps or the branch off of the PWP sump pumps discharge line depending on the system’s operational mode. Backwash inlet flow rates are controlled by a User input set point in “gpm” into the PLC

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HMI. The backwash inlet flow control valve (1RV-QW1405) modulates based on feedback from the backwash inlet flow meter (1FIT-QW1605) on the common backwash inlet line to maintain the backwash inlet flow rate set point. Backwash effluent water (outlet) from the vessel is sent to the backwash and rinse water tank or to the PWP depending on the operational mode, tank level permissives, or can be manually directed to the PWP by the User if necessary.

The required backwash flow rates to accomplish the required media expansion is, to a certain extent, dependent on the water temperature. As such, an option for temperature compensated/biased backwash flow rate adjustment is available in the PLC. Initially backwash flow rates will be set manually to observe bed expansion and can be adjusted as additional operational experience is obtained. Backwash duration should be approximately 10 – 30 minutes.

The following are recommended flow rates for determining proper backwash flow rates based on water temperature ranges.

Temperature Flux Rate Flow (°F) (gpm/ft 2) (gpm) 40 – 50 11.8 454 50 – 60 14.2 547 60 – 70 16 616 70 – 80 18.5 712 80 – 90 20.7 797 90 – 100 22.9 882

4.9.8.3. Rinse / Filter-to-waste

4.9.8.3.1. Following backwashing the filter vessel is rinsed down to remove any excessive solids in the bed and/or lines and allow the filtered outlet water to stabilize to a certain degree to prevent inadvertent filtered outlet turbidity spikes. Filtered water (outlet) from the vessel that was just backwashed during the rinse step is sent the backwash / rinse water tank or to the PWP depending on the operational mode, tank level permissives, or can be manually directed to the PWP by the User if necessary. Rinse flow rates are controlled by a User input set point in “gpm” into the PLC HMI. The backwash inlet flow control valve modulates based on feedback from the backwash inlet flow meter on the common backwash inlet line to maintain the rinse flow rate set point.

4.9.9. Out of Service

4.9.9.1. When no flow is required to be processed through the MMF and they are anticipated to be offline for 3 – 7 days or longer, the MMF system will need to be protected from excessive biological growth within the filter media. This is to prevent excessive maintenance, unavailability, or accelerated / irreversible media fouling of the system. Ideally the filter vessels should be kept full of water and backwashed on a weekly or greater basis when out of service. However depending on plant operation(s) and length of time the filters are/will be out of service, extended media layup procedures may need to be developed.

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NOTE: Prevention of biological growth within the filter media when not in service can be difficult to predict and numerous factors (water temperature, organism growth rates, nutrient levels, etc.) affect this process. Therefore biological growth can occur within periods of less than 3 days or greater than 7 days and likley operational experience will need to factor into the biological control plan. Additionally since it can be difficult to completely “dry” out the media during an extended out of service period, periodic disinfection and/or alternate biological control may need to be considered. Should a “drained and dry” extended layup procedure be implemented it will likely be necessary to fully backwash and/or disinfect the media prior to returning it to service.

Typically routine backwashing can prevent biological growth within the media. To accomplish this two modes of “automatic” filter operation can be selected, “standby” or “offline”. In “standby” mode the filters are out of service and are automatically backwashed periodically to prevent biological growth. In “offline” mode the filters are backwashed manually by the User to prevent biological growth.

Should routine backwashing become ineffective and/or it becomes necessary to supplement the biological control within the media, periodic disinfection can be accomplished with the addition of sodium hypochlorite. This can be fed from the Lamella clarifier’s biocide injection skid into each individual filter vessel’s backwash inlet line. These will be temporary hose connections from the biocide dosing skid to the injection point. The filters will need to be out of service and filled with water. They can then be dosed with the appropriate level of hypochlorite to manage any potential biological activity. The best way to accomplish this is to dose the hypochlorite into the vessel and allow it to soak for approximately 0.5 – 4 hours depending on the anticipated growth. Then perform a standard backwash to remove the chemicals, this can be followed by a second backwash to reclassify the media as/if necessary.

4.9.10. Common MMF system valve position summary

O = Fully Open X = Fully Closed M = Modulating S = Standby (only used during backwashing) NA = Not Applicable BW = Backwash

Operation Description Valve ID Discharge Recirculation Standby Offline Backwash Fail/Trip Common inlet block 1HV-QW0105 O O O O O Inlet control valve isolation block-A 1HV-QW0205 O O O O O Inlet control valve isolation block-B 1HV-QW0305 O O O O O

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Operation Description Valve ID Discharge Recirculation Standby Offline Backwash Fail/Trip Inlet control valve bypass block 1HV-QW0405 X X X X X Common backwash inlet block 1HV-QW1905 O O O O O Backwash control valve isolation block-A 1HV-QW2005 O O O O O Backwash control valve isolation block-B 1HV-QW2105 O O O O O Backwash control valve bypass block 1HV-QW2205 X X X X X Filter inlet flow control 1RV-QW0105 M M X X NA X Backwash inlet flow control 1RV-QW1405 S S S S M X Filter outlet 1BV-QW2205 O X X X NA X Recirculation outlet 1BV-QW2305 X O O O NA O Backwash outlet 1BV-QW2405 S S S S O X

4.9.11. Filter vessel valve position summary

Note: All actuated valves on the filter vessels in this section’s table are equipped with limit switches to indicate valve position and operate as air to open, spring to close.

Operation BW BW BW BW BW BW Step 2 Step Step BW Step Step Step Step 1 Air 3 4 5 6 7 Valve Valve ID Service Drain scour Settle Refill Backwash Settle Rinse Standby Vessel 1 (1TK-QW3510) Vessel Inlet 1BV-QW0415 O X X X X X X X X BW Outlet 1BV-QW0515 X X X X X O X X X Rinse Inlet 1BV-QW0615 X X X X X X X O X BW/Refill Inlet 1BV-QW0815 X X X X O O X X X Rinse Outlet 1BV-QW0715 X X X X X X X O X Vessel Outlet 1BV-QW0915 O X X X X X X X X Air Inlet 1BV-QW1015 X X O X X X X X X Drain Down 1BV-QW1715 X O X X X X X X X Vent 1BV-QW1915 X O O O O X X X X Vessel Inlet 1HV-QW0815 O O O O O O O O O BW Inlet 1HV-QW2515 O O O O O O O O O BW/Rinse Outlet 1HV-QW1215 O O O O O O O O O Air Inlet 1HV-QW1715 O O O O O O O O O Drain Down 1HV-QW2615 O O O O O O O O O Vessel Outlet 1HV-QW1615 O O O O O O O O O Vent 1HV-QW2715 O O O O O O O O O

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Operation BW BW BW BW BW BW Step 2 Step Step BW Step Step Step Step 1 Air 3 4 5 6 7 Valve Valve ID Service Drain scour Settle Refill Backwash Settle Rinse Standby Drain 1HV-QW1815 X X X X X X X X X Vessel 2 (1TK-QW3520) Vessel Inlet 1BV-QW0425 O X X X X X X X X BW Outlet 1BV-QW0525 X X X X X O X X X Rinse Inlet 1BV-QW0625 X X X X X X X O X BW/Refill 1BV-QW0825 Inlet X X X X O O X X X Rinse Outlet 1BV-QW0725 X X X X X X X O X Vessel Outlet 1BV-QW0925 O X X X X X X X X Air Inlet 1BV-QW1025 X X O X X X X X X Drain Down 1BV-QW1725 X O X X X X X X X Vent 1BV-QW1925 X O O O O X X X X Vessel Inlet 1HV-QW0825 O O O O O O O O O BW Inlet 1HV-QW2525 O O O O O O O O O BW/Rinse 1HV-QW1225 Outlet O O O O O O O O O Air Inlet 1HV-QW1725 O O O O O O O O O Drain Down 1HV-QW2625 O O O O O O O O O Vessel Outlet 1HV-QW1625 O O O O O O O O O Vent 1HV-QW2725 O O O O O O O O O Drain 1HV-QW1825 X X X X X X X X X Vessel 3 (1TK-QW3530) Vessel Inlet 1BV-QW0435 O X X X X X X X X BW Outlet 1BV-QW0535 X X X X X O X X X Rinse Inlet 1BV-QW0635 X X X X X X X O X BW/Refill 1BV-QW0835 Inlet X X X X O O X X X Rinse Outlet 1BV-QW0735 X X X X X X X O X Vessel Outlet 1BV-QW0935 O X X X X X X X X Air Inlet 1BV-QW1035 X X O X X X X X X Drain Down 1BV-QW1735 X O X X X X X X X Vent 1BV-QW1935 X O O O O X X X X Vessel Inlet 1HV-QW0835 O O O O O O O O O BW Inlet 1HV-QW2535 O O O O O O O O O BW/Rinse 1HV-QW1235 Outlet O O O O O O O O O Air Inlet 1HV-QW1735 O O O O O O O O O Drain Down 1HV-QW2635 O O O O O O O O O Vessel Outlet 1HV-QW1635 O O O O O O O O O Vent 1HV-QW2735 O O O O O O O O O Drain 1HV-QW1835 X X X X X X X X X

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4.10. Abnormal Operations

4.10.1. Contaminated Lamella effluent storage tank

During/Following a significant process (Lamella clarifier) upset, should analysis or instrumentation indicate that the TSS (and/or turbidity) in the entire volume of the Lamella effluent storage tank is too high for treatment within the MMF or to discharge into outfall 201; the contents of the tank must be purged to the CPRP. To accomplish this, the User can select the “Contaminated Lamella Effluent Storage Tank” selection button on the PLC HMI “Lamella” screen, and the contents of the Lamella effluent storage tank are discharged directly to the CPRP.

Selecting this option closes the Lamella train outlet to effluent storage tank valves (1BV- QW0312/0322) and opens the Lamella train outlet to backwash / rinse water storage tank valves (1BV-QW0412/0422), sending all Lamella effluent directly to the backwash / rinse water storage tank. The MMF outlet flow control valve (if operating in CPRP treatment mode) (1RV-QW0105) and the Lamella effluent to outfall 201 flow control (1RV-QW1802) valves close. The User must manually close the Lamella effluent tank to backwash tank inlet block valve (1HV-QW5800*) and open the Lamella effluent tank to CPRP block valve (1HV-QW5700*), allowing for a direct flow path from the Lamella effluent transfer pumps to the CPRP.

(*) = Permissive position for the User to be able to select the “Contaminated Lamella Effluent Storage Tank” option. Selecting this option without these permissives met, the PLC HMI will display “Permissives not met” and will not proceed with the purge.

4.11. Lamella Sludge Processing (temporary operation)

4.11.1. TSS that has been removed from the CPRP discharge during the clarification process and the residual treatment chemicals (coagulant and flocculent) are ultimately disposed of through re-application to the coal pile. This occurs through a three step process (Lamella) clarification (initial TSS removal from the CPRP discharge), thickening (concentrating settled solids from the Lamella), and pressing (dewatering concentrated solids).

Lamella clarification was covered in previous sections. Thickening occurs in the Lamella sludge thickener tank (1TK-QW3200), described in section 3.7 and pressing occurs in the filter press (1FL-QW3000), described in section 3.8.

4.11.2. Initially the Lamella sludge thickener will not be equipped with a scraper mechanism to collect solids that have settled within the vessel. During the interim when operating the vessel without a scraper, to mitigate potential “dead” zones in the bottom of the vessel that may accumulate settled sludge, the filter press feed pumps will remain in operation when the system is processing water from the CPRP and recycle sludge through the tank. The filter press feed pumps will cycle water from the bottom of the Lamella sludge thickener vessel to the top continuously when the filter press is not in service, in an effort to keep the sludge moving and prevent un-even settling and/or “dead” zones within the vessel that may go anaerobic. When the filter press is in service the recycle valve (1BV- QW2002) closes and all of the filter press feed pump discharge is sent to the filter press. A 3-way solenoid valve regulates the pressure (flow) for the filter press feed pumps to

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accommodate both modes of operation in the interim (recirculation, high flow/low pressure and filter press feed, variable flow/variable (high) pressure).

4.11.3. To manage sludge inventor in the Lamella clarifiers, the User will need to adjust the sludge transfer pump operation as needed. This is largely dependent on the Lamella influent solids loadings (influent TSS and chemical feed(s)) and operational experience. Sludge transferred from the Lamella underflow is sent to the Lamella sludge thickener from the sludge transfer pumps through an (temporary) open ended tee connection discharging approximately 4 to 5-feet below the top of the thickener vessel.

4.11.4. Overflow from the thickener vessel is directed to the Lamella influent mix tanks, depending upon which Lamella train(s) are in operation.

4.11.5. Should TSS levels in the thickener overflow seem excessive and/or sludge settling seem unacceptable, a flocculent can be fed into the individual sludge transfer pump feed lines as needed. These set points are adjustable in the PLC HMI “Chemical Feed” page.

4.11.6. Once sufficient solids have collected / concentrated in the sludge thickener the User has several options available to determine if it is acceptable to begin a filter press run.

(1) Analyze a TSS sample from one of the 4 bottom/side sample ports (ideal sample port sample location may require some trial-and-error / operational experience to evaluate the optimal or best representative sample location). A TSS sample in the 1 – 5% range will typically indicate acceptable solids concentrations to begin a filter press run.

(2) Analyze a settled solids density sample (V/V) from one of the 4 bottom/side sample ports (ideal sample port sample location and V/V settled sludge results analysis may require some trial-and-error / operational experience to evaluate the optimal or best representative sample location and analysis results for an acceptable filter press run).

(3) Sludge level indication provided by the vessel level instrumentation (1LIT-QW0702) (ideal sludge bed levels observed to determine an acceptable filter press run may require some trial-and-error / operational experience).

(4) Treatment system operating flow rates / operating conditions / operational experience / etc. that necessitate filer press operation to manage solids inventories and maintain pond levels.

4.11.7. Once the User determines that a filter press run can begin, the User will navigate to the “Filter Press” page on the PLC HMI. If the status on the PLC HMI “Filter Press” screen indicates “Ready” the User can select the option “Begin Filter Press Run”. Signal/Status from the filter press skid will largely provide the permissives for the “Ready” status on the PLC HMI, though one operational permissive that the User must check/verify/complete is the status of the filter press feed valve (1HV-QW2700), which must be open. Once the User selects this option the filter press run is started and the sludge recirculation valve closes and the filter press skid steps through it sequencing until the filter press run is complete.

4.11.8. Status from the filter press skid is sent to the PLC and indications of the press sequencing and completion will be displayed on / transmitted by the PLC HMI “Filter Press” screen. Once a filter press run is complete the PLC HMI will display “Press Complete”. The

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User will then need to begin the process of separating the filter press plates, dumping the dewatered sludge into a roll-off dumpster.

4.12. Filter Press Operation

4.12.1. Detailed filter press operation is covered in the Siemens O&M manual

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5. Operation valve line up (standard operation)

NOTE: Valve positions for the MMF system and vessels provided in sections 4.9.10 and 4.9.11

5.1. CPRP Treatment

O = Fully Open Treatment Options X = Fully Closed 1. MMF treatment discharging to the PWP M = Modulating 2. MMF treatment discharging to outfall 201 Z = Varies Depending on Operation 3. MMF treatment and Lamella effluent combined discharge to outfall 201 * = Permissive Status 4. Lamella effluent direct discharge to PWP

Treatment Option 1st Stage 2nd Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 3 4 Position CPRP High Flow Bypass Block 1HV-WW4403 X* X* X* X* X* X* X* CPRP Supply to Treatment System Block 1HV-WW4303 O* O* O* O* O* O* O* Treatment System Return to Outfall 201 Header Block 1HV-WW4503 O* O* O* O* O* O* O* CPRP Low Flow Pump to Treatment Header Block 1HV-WW4103 O O O O O O O CPRP Low Flow Pump to Future User Block 1HV-WW4203 X X X X X X X Lamella Train 1 Inlet Block 1HV-QW0310 O O O O O O O Lamella Train 1 Inlet Flow Control 1RV-QW0112 X M M M M M M X Lamella Train 2 Inlet Block 1HV-QW0320 O O O O O O O Lamella Train 2 Inlet Flow Control 1RV-QW0122 X M M M M M M X Coagulant Inlet Block 1HV-QW0200 O O O O O O O

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Treatment Option 1st Stage 2nd Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 3 4 Position Lamella Train 1 Flocculent Inlet Block 1HV-QW0610 O O O O O O O Lamella Train 2 Flocculent Inlet Block 1HV-QW0620 O O O O O O O Lamella Train 1 Thickener Overflow Inlet Block 1BV-QW1012 Z Z Z Z Z Z Z Lamella Train 2 Thickener Overflow Inlet Block 1BV-QW1022 Z Z Z Z Z Z Z Lamella Train 1 Sludge Transfer Pump A Suction 1HV-QW0911 O O O O O O O Lamella Train 1 Sludge Transfer Pump B Suction 1HV-QW0912 O O O O O O O Lamella Train 2 Sludge Transfer Pump A Suction 1HV-QW0921 O O O O O O O Lamella Train 2 Sludge Transfer Pump B Suction 1HV-QW0922 O O O O O O O Lamella Train 1 Sludge Transfer Pump A Discharge 1HV-QW1511 O O O O O O O Lamella Train 1 Sludge Transfer Pump B Discharge 1HV-QW1512 O O O O O O O Lamella Train 2 Sludge Transfer Pump A Discharge 1HV-QW1521 O O O O O O O Lamella Train 2 Sludge Transfer Pump B Discharge 1HV-QW1522 O O O O O O O Lamella Train 1 Outlet to Effluent Storage Tank 1BV-QW0312 X X* O* O O O O X Lamella Train 1 Outlet to Backwash / Rinse Water Storage Tank 1BV-QW0412 O O* X* X X X X O Lamella Train 2 Outlet to Effluent Storage Tank 1BV-QW0322 X X* O* O O O O X

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Treatment Option 1st Stage 2nd Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 3 4 Position Lamella Train 2 Outlet to Backwash / Rinse Water Storage Tank 1BV-QW0422 O O* X* X X X X O Lamella Effluent Storage Tank Outlet Block 1HV-QW3800 O O O O O O O Lamella Effluent Transfer Pump A Suction Block 1HV-QW3910 O O O O O O O Lamella Effluent Transfer Pump B Suction Block 1HV-QW3920 O O O O O O O Lamella Effluent Transfer Pump A Discharge Block 1HV-QW4110 O O O O O O O Lamella Effluent Transfer Pump B Discharge Block 1HV-QW4120 O O O O O O O Lamella Effluent to 201 Block 1HV-QW4700 O O O X X O X Lamella Effluent to 201 Flow Control 1RV-QW1802 X X X X* X* M X* X MMF Lamella Inlet Double Block A 1HV-QW4800 O O O O O O X* MMF Lamella Inlet Double Block B 1HV-QW4900 O O O O O O X* MMF Lamella Inlet Double Block Bleed 1HV-QW7000 X X X X X X O Lamella Sludge Thickener Tank Underflow Block 1HV-QW1900 O O O O O O O Filter Press Feed Pump A Suction Block 1HV-QW2010 O O O O O O O Filter Press Feed Pump B Suction Block 1HV-QW2020 O O O O O O O Filter Press Feed Pump A Discharge Block 1HV-QW2510 O O O O O O O Filter Press Feed Pump B Discharge Block 1HV-QW2520 O O O O O O O

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Treatment Option 1st Stage 2nd Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 3 4 Position Lamella Sludge Thickener Recycle Block 1BV-QW2002 Z Z Z Z Z Z Z Filter Press Feed Block 1HV-QW2700 Z Z Z Z Z Z Z Filter Press Filtrate to Lamella Effluent Storage Tank Block 1HV-QW3500 Z Z Z Z Z Z Z Filter Press Filtrate to Trench Block 1HV-QW3400 Z Z Z Z Z Z Z PWP Sump Discharge to MMF Double Block A 1HV-QW8000 X* X X X* X* X* X PWP Sump Discharge to MMF Double Block B 1HV-QW8200 X* X X X* X* X* X PWP Sump Discharge to MMF Double Block Bleed 1HV-QW8100 O O O O O O O MMF Outlet to 201 Double Block A 1HV-QW7700 O O O X* O* O* X* MMF Outlet to 201 Double Block B 1HV-QW7900 O O O X* O* O* X* MMF Outlet to 201 Double Block Bleed 1HV-QW7800 X X X X X X X MMF Outlet to 101 Double Block A 1HV-QW7400 X* X X X* X* X* X MMF Outlet to 101 Double Block B 1HV-QW7600 X* X X X* X* X* X MMF Outlet to 101 Double Block Bleed 1HV-QW7500 O O O O O O O MMF Backwash Outlet to PWP Block 1HV-QW5000 X X X X* X* X* X MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block A 1HV-QW5100 O O O O* O* O* O

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Treatment Option 1st Stage 2nd Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 3 4 Position MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block B 1HV-QW5300 O* O O O O* O* O* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block Bleed 1HV-QW5200 X X X X X X X Lamella Effluent Tank to Backwash Tank / CPRP Double Block A 1HV-QW5400 O O O O O O O Lamella Effluent Tank to Backwash Tank / CPRP Double Block B 1HV-QW5600 O O O O O O O Lamella Effluent Tank to Backwash Tank / CPRP Double Block Bleed 1HV-QW5500 X X X X X X X Lamella Effluent Tank to Backwash Tank / CPRP Control Valve 1RV-QW1902 X X O M M M M O Lamella Effluent Tank to Backwash Tank Inlet Block 1HV-QW5800 O O Z O* O* O* O Lamella Effluent Tank to CPRP Block 1HV-QW5700 X X Z X X X X Backwash / Rinse Effluent Storage Tank Outlet Block 1HV-QW6200 O O O O O O O Backwash / Rinse Effluent Transfer Pump A Suction Block 1HV-QW6310 O O O O O O O Backwash / Rinse Effluent Transfer Pump B Suction Block 1HV-QW6320 O O O O O O O Backwash / Rinse Effluent Transfer Pump A Discharge Block 1HV-QW6510 O O O O O O O Backwash / Rinse Effluent Transfer Pump B Discharge Block 1HV-QW6520 O O O O O O O

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5.2. PWP Treatment

O = Fully Open X = Fully Closed M = Modulating Z = Varies Depending on Operation * = “Ready” Permissive

Discharge Fail/Trip Description Valve ID Ready to 101 Position MMF Lamella Inlet Double Block A 1HV-QW4800 X* X* MMF Lamella Inlet Double Block B 1HV-QW4900 X* X* MMF Lamella Inlet Double Block Bleed 1HV-QW7000 O O PWP Sump Discharge to MMF Double Block A 1HV-QW8000 O* O* PWP Sump Discharge to MMF Double Block B 1HV-QW8200 O* O* PWP Sump Discharge to MMF Double Block Bleed 1HV-QW8100 X X MMF Outlet to 201 Double Block A 1HV-QW7700 X* X* MMF Outlet to 201 Double Block B 1HV-QW7900 X* X* MMF Outlet to 201 Double Block Bleed 1HV-QW7800 O O MMF Outlet to 101 Double Block A 1HV-QW7400 O* O* MMF Outlet to 101 Double Block B 1HV-QW7600 O* O* MMF Outlet to 101 Double Block Bleed 1HV-QW7500 X X MMF Backwash Outlet to PWP Block 1HV-QW5000 O* O* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block A 1HV-QW5100 X* X* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block B 1HV-QW5300 X* X* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block Bleed 1HV-QW5200 O O

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5.3. Dual Treatment

O = Fully Open Treatment Options X = Fully Closed 1. CPRP discharging to outfall 201, PWP discharging to outfall 101 M = Modulating 2. CPRP discharging to PWP, PWP discharging to outfall 101 Z = Varies Depending on Operation * = “Ready” Permissive

Treatment Option 1st 2nd Stage Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 Position CPRP High Flow Bypass Block 1HV-WW4403 X* X X X X CPRP Supply to Treatment System Block 1HV-WW4303 O* O O O O Treatment System Return to Outfall 201 Header Block 1HV-WW4503 O* O O O O CPRP Low Flow Pump to Treatment Header Block 1HV-WW4103 O O O O O CPRP Low Flow Pump to Future User Block 1HV-WW4203 X X X X X Lamella Train 1 Inlet Block 1HV-QW0310 O O O O O Lamella Train 1 Inlet Flow Control 1RV-QW0112 X M M M M X Lamella Train 2 Inlet Block 1HV-QW0320 O O O O O Lamella Train 2 Inlet Flow Control 1RV-QW0122 X M M M M X Coagulant Inlet Block 1HV-QW0200 O O O O O Lamella Train 1 Flocculent Inlet Block 1HV-QW0610 O O O O O Lamella Train 2 Flocculent Inlet Block 1HV-QW0620 O O O O O Lamella Train 1 Thickener Overflow Inlet Block 1BV-QW1012 Z Z Z Z Z

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Treatment Option 1st 2nd Stage Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 Position Lamella Train 2 Thickener Overflow Inlet Block 1BV-QW1022 Z Z Z Z Z Lamella Train 1 Sludge Transfer Pump A Suction 1HV-QW0911 O O O O O Lamella Train 1 Sludge Transfer Pump B Suction 1HV-QW0912 O O O O O Lamella Train 2 Sludge Transfer Pump A Suction 1HV-QW0921 O O O O O Lamella Train 2 Sludge Transfer Pump B Suction 1HV-QW0922 O O O O O Lamella Train 1 Sludge Transfer Pump A Discharge 1HV-QW1511 O O O O O Lamella Train 1 Sludge Transfer Pump B Discharge 1HV-QW1512 O O O O O Lamella Train 2 Sludge Transfer Pump A Discharge 1HV-QW1521 O O O O O Lamella Train 2 Sludge Transfer Pump B Discharge 1HV-QW1522 O O O O O Lamella Train 1 Outlet to Effluent Storage Tank 1BV-QW0312 X X* O* O O X Lamella Train 1 Outlet to Backwash / Rinse Water Storage Tank 1BV-QW0412 O O* X* X X O Lamella Train 2 Outlet to Effluent Storage Tank 1BV-QW0322 X X* O* O O X Lamella Train 2 Outlet to Backwash / Rinse Water Storage Tank 1BV-QW0422 O O* X* X X O Lamella Effluent Storage Tank Outlet Block 1HV-QW3800 O O O O O Lamella Effluent Transfer Pump A Suction Block 1HV-QW3910 O O O O O

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Treatment Option 1st 2nd Stage Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 Position Lamella Effluent Transfer Pump B Suction Block 1HV-QW3920 O O O O O Lamella Effluent Transfer Pump A Discharge Block 1HV-QW4110 O O O O O Lamella Effluent Transfer Pump B Discharge Block 1HV-QW4120 O O O O O Lamella Effluent to 201 Block 1HV-QW4700 O O O O X Lamella Effluent to 201 Flow Control 1RV-QW1802 X X X M X* X MMF Lamella Inlet Double Block A 1HV-QW4800 X* X* X* X* X* MMF Lamella Inlet Double Block B 1HV-QW4900 X* X* X* X* X* MMF Lamella Inlet Double Block Bleed 1HV-QW7000 O O O O O Lamella Sludge Thickener Tank Underflow Block 1HV-QW1900 O O O O O Filter Press Feed Pump A Suction Block 1HV-QW2010 O O O O O Filter Press Feed Pump B Suction Block 1HV-QW2020 O O O O O Filter Press Feed Pump A Discharge Block 1HV-QW2510 O O O O O Filter Press Feed Pump B Discharge Block 1HV-QW2520 O O O O O Lamella Sludge Thickener Recycle Block 1BV-QW2002 Z Z Z Z Z Filter Press Feed Block 1HV-QW2700 Z Z Z Z Z Filter Press Filtrate to Lamella Effluent Storage Tank Block 1HV-QW3500 Z Z Z Z Z Filter Press Filtrate to Trench Block 1HV-QW3400 Z Z Z Z Z PWP Sump Discharge to MMF Double Block A 1HV-QW8000 O O O O O PWP Sump Discharge to MMF Double Block B 1HV-QW8200 O O O O O PWP Sump Discharge to MMF Double Block Bleed 1HV-QW8100 X X X X X

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Treatment Option 1st 2nd Stage Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 Position MMF Outlet to 201 Double Block A 1HV-QW7700 X* X* X* X* X* MMF Outlet to 201 Double Block B 1HV-QW7900 X* X* X* X* X* MMF Outlet to 201 Double Block Bleed 1HV-QW7800 O O O O O MMF Outlet to 101 Double Block A 1HV-QW7400 O* O O O* O* MMF Outlet to 101 Double Block B 1HV-QW7600 O* O O O* O* MMF Outlet to 101 Double Block Bleed 1HV-QW7500 X X X X X MMF Backwash Outlet to PWP Block 1HV-QW5000 O O O O* O* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block A 1HV-QW5100 X* X* X* X* X* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block B 1HV-QW5300 X* X* X* X* X* MMF Backwash Outlet to Backwash / Rinse Water Storage Tank Double Block Bleed 1HV-QW5200 O O O O O Lamella Effluent Tank to Backwash Tank / CPRP Double Block A 1HV-QW5400 O O O O O Lamella Effluent Tank to Backwash Tank / CPRP Double Block B 1HV-QW5600 O O O O O Lamella Effluent Tank to Backwash Tank / CPRP Double Block Bleed 1HV-QW5500 X X X X X Lamella Effluent Tank to Backwash Tank / CPRP Control Valve 1RV-QW1902 X X O Z Z O Lamella Effluent Tank to Backwash Tank Inlet Block 1HV-QW5800 O* O Z O O Lamella Effluent Tank to CPRP Block 1HV-QW5700 X* X Z X X Backwash / Rinse Effluent Storage Tank Outlet Block 1HV-QW6200 O O O O O Backwash / Rinse Effluent Transfer Pump A Suction Block 1HV-QW6310 O O O O O Backwash / Rinse Effluent Transfer Pump B Suction Block 1HV-QW6320 O O O O O

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Treatment Option 1st 2nd Stage Stage Fail/Trip Description Valve ID Ready Startup Startup 1 2 Position Backwash / Rinse Effluent Transfer Pump A Discharge Block 1HV-QW6510 O O O O O Backwash / Rinse Effluent Transfer Pump B Discharge Block 1HV-QW6520 O O O O O

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5.4. Valve Status and Response

Action on Fail/Trip Description Valve ID Status Fail to open Fail to close Lamella Train 1 1RV-QW0112 X Local Alarm Common Alarm Inlet Flow Control Lamella Train 2 1RV-QW0122 X Local Alarm Common Alarm Inlet Flow Control Lamella Train 1 Thickener 1BV-QW1012 X Local Alarm Local Alarm Overflow Inlet Block Lamella Train 2 Thickener 1BV-QW1022 X Local Alarm Local Alarm Overflow Inlet Block Lamella Train 1 Common Alarm – Closes Outlet to Effluent 1BV-QW0312 X Local Alarm Lamella influent control valve Storage Tank (1RV-QW0112) Lamella Train 1 Outlet to Backwash 1BV-QW0412 O Local Alarm Common Alarm / Rinse Water Storage Tank Lamella Train 2 Common Alarm – Closes Outlet to Effluent 1BV-QW0322 X Local Alarm Lamella influent control valve Storage Tank (1RV-QW02) Lamella Train 2 Outlet to Backwash 1BV-QW0422 O Local Alarm Common Alarm / Rinse Water Storage Tank Common Alarm – Trips Lamella Effluent to 1RV-QW1802 X Local Alarm Lamella effluent transfer 201 pumps Common Alarm and PLC Filter inlet flow moves into “recirculation” 1RV-QW0105 X Common Alarm control mode if flow is > 0 gpm on outlet flow meter Common Alarm and PLC Common Alarm and PLC “locks” out vessel that was “locks” out vessel that was Backwash inlet backwashed if flow on the 1RV-QW1405 X queued for backwash, one flow control backwash inlet flow meter is > failed backwash sequence is 0 gpm, further PLC action logged based on operating mode Common Alarm and PLC Common Alarm and PLC trips Filter outlet 1BV-QW2205 X moves into “recirculation” 1RV-QW0105 mode Common Alarm and PLC trips Recirculation outlet 1BV-QW2305 O 1RV-QW0105 if flow on outlet Common Alarm flow meter is > 0 gpm

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Common Alarm and PLC logs Common Alarm and PLC trips one failed backwash sequence, Backwash outlet 1BV-QW2405 X 1RV-QW1405 if backwash PLC closes 1RV-QW1405 if inlet flow is > 0 gpm backwash inlet flow is > 0 gpm Lamella Effluent Tank to Backwash 1RV-QW1902 O Common Alarm Local Alarm Tank / CPRP Control Valve Thickener Underflow 1BV-QW2002 X Local Alarm Local Alarm Recirculation

6. Alarms / Set points

6.1. Alarms

Common Alarm – Signal sent from PLC to plant DCS Local Alarm – Alarm condition displayed on / transmitted by PLC HMI only

Alarm Levels and Actions

Low- High- Parameter Unit Low Action Low Action High Action High Action Common Alarm – Lamella Inf. Stand by pump Local Local Flow gpm 80 started if off 100 Alarm 850 Alarm NA Lamella Mixer Run Trip Local Alarm Common Alarm – Further action Lamella based on Train Eff. Local option(s) Turbidity NTU NA NA NA NA 25 Alarm 50 selected Removes MMF backwash Lamella Eff. sequence Local Local Common Tank Level ft permissive Alarm Alarm Alarm Common Alarm – Directs flow to Lamella Eff. Local Backwash Tank Turb. NTU NA NA NA NA 25 Alarm 50 Storage Tank Lamella Eff. Tank Local Alarm – Discharge Trips duty pump Local Local Pressure psig and starts standby Alarm Alarm Local Alarm Common Alarm – Removes MMF backwash BW Tank Local sequence Level ft Alarm permissive

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BW. Tank Local Flow gpm Local Alarm Alarm BW Tank Local Alarm – Discharge Trips duty pump Local Local Pressure psig and starts standby Alarm Alarm Local Alarm Local Alarm – Thickener Stops transfer Local Local Common Level ft pump(s) Alarm Alarm Alarm Filter Press Local Alarm – Feed Trips duty pump Local Local Pressure psi and starts standby Alarm Alarm Local Alarm MMF Inlet Local Common Turbidity NTU NA NA NA NA 100 Alarm 250 Alarm

Common Alarm and PLC moves into MMF Outlet Common “recirculation” Turbidity NTU NA NA NA NA 25 Alarm 50 mode Common Alarm Common and PLC moves Alarm and PLC into moves into “recirculation” Common Common “recirculation” Inlet pH 6.3 mode 6.8 Alarm 8.2 Alarm 8.7 mode MMF Vessel Local Local Common Outlet Flow gpm 75 Common Alarm 100 Alarm 175 Alarm 200 Alarm Common Common Alarm Alarm and PLC and PLC restarts suspends backwash step 5, backwash, one one failed failed MMF backwash backwash Backwash sequence is Common Common sequence is Flow gpm 400 logged 450 Alarm 900 Alarm 1000 logged PLC places Local Alarm vessel and PLC places MMF Vessel into vessel into Differential backwas backwash Pressure psid NA NA NA NA 15 h queue 25 queue

MMF Vessel Common Backwash Alarm and PLC Sequence “locks” vessel Failures NA NA NA NA NA NA 3 out of service

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7. PLC control set points

Parameter Unit Minimum Maximum Initial PWP Stop MMF inlet flow ft Start MMF inlet flow ft MMF treatment level ft Lamella System Influent Flow gpm 100 800 Train 1 Influent Flow gpm 100 400 Train 2 Influent Flow gpm 100 400 Coagulant Dose ppm 0 200 Coagulant Specific Gravity NA NA Coagulant Dosing Pump Max ml/min Flocculent Dose ppm 0 10 Flocculent Solution % Flocculent Dosing Pump Max ml/min Train 1 Sludge Pump On minutes Train 1 Sludge Pump Off minutes Train 2 Sludge Pump On minutes Train 2 Sludge Pump Off minutes Lamella Effluent Tank Backwash Permissive Level ft Backwash / Rinse Water Storage Tank Backwash Permissive Level ft Maximum High Level Time minutes Multi-Media Filter (MMF) Total Outlet Flow gpm 100 800 550 Vessel Idle Time hours 12 600 72 Vessel Standby / Backwash Timer hours 0 720 72 Vessel Maximum Throughput gallons NA 100,000 4,200 MMF Backwashing Flow gpm 400 900 575 Drain Down Time minutes TBD TBD TBD Air Scour Time minutes 0 60 5 Settle Time minutes 0 60 TBD Refill Time minutes TBD 60 TBD Backwash Time minutes 5 60 10 Settle Time minutes 0 60 TBD Rinse Time minutes 0 240 10 Rinse Flow gpm 100 300 230 Sludge Thickener

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Parameter Unit Minimum Maximum Initial Sludge Level ft Rake Torque ft-lbs Filter Press TBD

8. Reserved for future use

9. Reserved for future use

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