I.I.I.I.I. FOREW FOREW FOREW FOREW FOREWORDORDORDORDORD

Daily care and operation of a wastewater treatmentsystem plays a major role in determining the degree oftreatment attained. Plants may be properly sized andadjusted yet produce sub-standard results because of alack of operational control. Complete instructions for operating your Norwecowastewater treatment system are given in this manual. Byfamiliarizing yourself with the system and the contents ofthis manual you will be able to obtain superior treatmentresults.

Originally founded in 1906, Norweco has years ofexperience in the pollution control field. “Progress throughservice - since 1906” sums it up nicely. Norweco equipmentis currently in use in thousands of places throughout theworld - hundreds of manufacturers in the pollution controlfield, large and small alike, are now using Norwecoequipment. Norweco systems are installed and serviced only byfactory trained dealers. A quality product - serviced by alocal expert - has earned Norweco a reputation forexcellence.

II.II.II.II.II. TTTTTABLE OF CONTENTSABLE OF CONTENTSABLE OF CONTENTSABLE OF CONTENTSABLE OF CONTENTS

Norweco Operation and Maintenance ManualCHAPTER TITLE PAGE

I. Foreword . . . . . . . . . . . . . . . . . . . . . . . .Inside Cover

II. Table of Contents . . . . . . . . . . . . . . . . . Inside Cover

III. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

IV. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

V. Plant Start-up. . . . . . . . . . . . . . . . . . . . . . . . . . .4-5-6

VI. Plant Operation. . . . . . . . . . . . . . . . . . . . . . .6-7-8-9

VII. Plant Maintenance. . . . . . . . . . . . . . . . . . . . . . . 9-10

VIII. Special Instructions for TRAVALAIR™ Unit . . . . . 10

IX. Mechanical Equipment Maintenance. . . . . 10-11-14

X. Labeled Cutaway of Plant . . . . . . . . . . . . . . . .12-13

CHAPTER TITLE PAGE

XI. Equipment Lubrication. . . . . . . . . . . . . . . . . . .14-15

XII. Electrical Equipment Maintenance. . . . . . . . . . . .15

XIII. Plant Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . . .15

XIV. Visual Checklist. . . . . . . . . . . . . . . . . . . . . . . . . . 16

XV. Maintenance Schedule Check List. . . . . . . . . 17-18

XVI. Trouble Shooting. . . . . . . . . . . . . . . . . . . . . . . . . 19

XVII. Optional Equipment . . . . . . . . . . . . . . . . . . . . 20-21

XVIII. Testing and Evaluation . . . . . . . . . . . . . . . . . 21-22

IXX. Maintenance Record . . . . . . . . . . . . . . . . . . . . . 23

XX. Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

III.III.III.III.III. INTR INTR INTR INTR INTRODUCTIONODUCTIONODUCTIONODUCTIONODUCTION Norweco wastewater treatment plants operate on theExtended Aeration principle using microscopic organisms,in the presence of oxygen, to destroy organic compoundsin the sewage. Incoming wastewater passes through threeprogressive stages of treatment before being dischargedfrom the plant. In addition, a number of accessory treatmentdevices may be added to the basic system to provide evenhigher purification. These optional devices vary accordingto individual requirements and are described in the “OptionalEquipment” section of this manual. However, the basictreatment process does not change and is as described inthe following pages.PRE-TREATMENT First, incoming sewage passes through a conditioningdevice that removes untreatable objects and prevents themfrom entering the aeration chamber. Pre-treatment orconditioning may be accomplished by using a comminutor,bar screen or trash trap. Trash traps are holding tanksused to settle out untreatable objects, bar screens merelyscreen incoming sewage and comminutors grind andscreen the sewage before passing it to the second phaseof treatment.AERATION After pre-treatment, the conditioned wastewater entersthe aeration chamber of the plant where the bulk of theorganic compounds are eliminated. Norweco’s aerationchamber is designed to hold the wastewater for twenty-four hours while aerobic bacteria, present in the chamber,destroy the organic material. To obtain such completetreatment in just twenty-four hours it is necessary to providejust the right environment for the bacteria. This isaccomplished by the controlled introduction of oxygen intothe chamber. Norweco’s unique “Evenair” diffusers aredesigned just for this purpose. They are installed in thebottom of the chamber to provide even distribution of oxygeninto the aeration tank. Stimulated by the abundant supplyof oxygen, the bacteria multiply rapidly and are thoroughlymixed with the tank contents to insure complete oxidationof all organic material.CLARIFICATION After twenty-four hours in the aeration chamber the liquidflows into the settling/clarification chamber. Settling isprovided to remove activated sludge and small organicparticles suspended in the liquid so the purified effluentmay be discharged from the plant. The lower sidewalls ofthe chamber are slanted to form a hopper. As thesuspended particles settle toward the bottom they areguided into a small area in the center of the hopper by theslanted sidewalls. Here the particles are picked up by theairlift sludge pump and returned to the aeration chamberfor final treatment. This process of removing the activatedsludge and suspended particles from the liquid leaves onlya clear, highly treated water at the top of the chamber. It isthis clear, odorless liquid at the top of the tank that isdischarged from the system.IVIVIVIVIV..... INST INST INST INST INSTALLAALLAALLAALLAALLATIONTIONTIONTIONTION Norweco wastewater treatment systems are sold,installed and serviced by factory trained Norwecodistributors. They are fully trained regarding installation ofNorweco products and are able to provide all necessaryjob coordination to insure a simple, economical installation.

Norweco systems are sold as complete installationsincluding delivery, tank setting, equipment installation, start-up and service. This unusual “complete sales policy” greatlysimplifies plant installation for the owner and eliminateshidden charges for items such as freight, equipment start-up, tank installation, etc. Work that is not included with the Norweco system mustbe checked for completion by the owner before start-up ofthe plant. Plant excavation, tank pad, backfill, influent andeffluent sewer lines, electrical power to the equipment, fillingof tanks with water, finish grading, landscaping and seedingare not included with the plant. Generally, they are theresponsibility of the general contractor or excavatingcontractor and the plant owner must insure that these itemsare taken care of prior to equipment start-up. Excavation for the wastewater treatment plant shouldbe coordinated with the Norweco distributor to insure thatthe system is installed as soon as possible after completionof the excavation. Generally, the excavation should be atleast two feet wider and two feet longer than the treatmentplant and at least four inches of sand should be placed inthe bottom of the excavation. The excavation should be free and clear of all obstacleson at least two sides to permit entrance and setting ofindividual tank components. Be sure to consult your localNorweco distributor prior to plant excavation if this causesany unnecessary problems.SAND LEVELING PAD Four to six inches of sand or very fine stone should beplaced in the bottom of the excavation to provide a levelingcourse for the individual tanks in the treatment system. Thiswill permit speedy installation of the components andeliminate the excess work, time and expense required tomanually level the bottom of the excavation. The padpermits the bottom to be leveled perfectly so that all tanksand components will align at grade in the completed system.It also provides protection for the bottoms of the individualtanks and prevents any unnecessary strain on the tanksafter they have been filled with water. In special cases where soil conditions are particularlypoor it may be necessary to install a poured concrete padin the excavation. This, of course, must be determinedwith regard to your particular location.BACKFILL After the tanks have been set, the contractor must backfillbetween each tank and around the outside of all tanks. Allfill between individual tank sections must be sand or veryfine stone. Backfill around the outside of the tanks can bewith the original material. However, care must be taken toinsure that no large clumps of earth or rocks are pushed inagainst the tanks. Caution the excavating contractor totake care while backfilling in and around all tank sectionsof the wastewater treatment facility.FILLING of TANKS WITH WATER Individual tank sections and components of thetreatment facility should be filled with water as backfilling istaking place. Tanks should not be allowed to sit overnightwithout water in them because they may float if largevolumes of surface water enter the excavation. If possible,the tanks should have water in them to a level equal to thelevel of the backfill. By backfilling and filling the tanks withwater at the same time you will eliminate all unnecessarypressure on the tank and related structure.

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SEWER LINES Installation of influent (inlet) and effluent (outlet) sewer

lines are the treatment plant owner’sresponsibility. All lines must beinstalled in accordance with State andlocal codes and several precautionsshould be taken in the immediate areaof the wastewater facility. First, be sureall lines to and from the plant, as wellas other sewer lines connectingindividual elements of the plant, areinstalled on good solid fill. Loose fillthat might settle later on may create a

low spot or leak in the line. Be sure to discuss hook-up ofthe lines to the tanks with your Norweco distributor. Check

to insure that all lines are installed atthe correct location and the properelevation. Where possible, a one piecesection of cast iron should be usedfrom the tank wall to a solid section ofundisturbed earth beyond the limits ofthe plant excavation. Although incertain cases this is not possible,special precautions should be taken toinsure that the lines are on solid fill withas few joints as possible.

ELECTRICAL POWER Underground electrical power must be brought to theplant site for hook-up of the individual treatment plantcomponents. General information as to the overallhorsepower rating of the system and related equipment,as well as other electrical needs, should be obtained fromthe Norweco distributor. In most cases, it is desirable tobring the electrical power to the plant site underground andup and out of the ground immediately adjacent to thetreatment plant. Here a master disconnect switch must beprovided to cut power to the entire facility. Ask your Norwecodistributor about the electrical requirements and be sure aproperly sized disconnect is provided. Detailed instructionsfor distribution of power from the master panel to theindividual components of the wastewater facility will beprovided by your distributor. Individual wiring diagrams ofthe control panels and other elements within the systemwill also be provided by the Norweco distributor. Have yourelectrician complete the electrical hook-up but do not havehim place any of the equipment into operation. After theelectrical hook-up is complete and the other elements ofthe plant installation are taken care of contact the localNorweco distributor and have him start-up the individualelements.GRADING, LANDSCAPING, SEEDING ANDFENCING

Finishing touches and earth workaround the sewage treatment systemare important parts of the overallinstallation. Grading, landscaping,seeding and other related items willmake a difference in the finishedappearance of the plant and also mayhave an effect on the operation of thesystem.

Grade around the treatment plant must be set up sothat surface water does not drain to the treatment plantarea or into the top of the treatment plant proper. Theelimination of surface and storm water from the sanitarysewage flow and treatment facility must be considered priorto installation. Fencing should not be overlooked when a system isinstalled. A fence protects the system from maliciousdamage and eliminates entrance by unauthorized persons.It may also eliminate an accident with domestic animals orchildren in the area. Many plant owners construct attractivered wood or lattice work fences and completely concealtheir treatment system. When the plant is located in anarea that does not require special landscaping the use of aseventy-two inch chain link fence is recommended.JOB RESPONSIBILITIES Prior to the installation of a plant a clear definition ofresponsibility should be given to all of the parties involved.It is an important factor and will affect the overall cost andtime required to install the plant. The best way to savetime, money and headaches when purchasing or installinga wastewater treatment facility is to have a meeting with allof the parties involved prior to the start of any work. Theowner should contact the engineer in charge, the generalcontractor and/or the excavating contractor, the electricianand the Norweco distributor. Exact requirements for theexcavating contractor and electrician may be obtained fromthe Norweco distributor. Have him work with the projectengineer to insure that all equipment is provided as detailedin the original plan and approved drawings.PLANT OPERATOR The owner must appoint a qualified person as theoperator of the wastewater treatment facility. During thefirst twelve months of plant operation the Norweco distributorwill make at least ten inspections of the facility to adjustequipment and service the system. The operator shouldmeet with the distributor during each visit to get a clearunderstanding of the overall system and the function ofeach element within the system. Several types of standard service policies are availableto provide regular qualified service after the initial one yearpolicy expires. However, it is still necessary to provideroutine maintenance and service of the system on a dailybasis. Day to day operation of the system will be the mainfactor involved in determining the treatment results. It ismost important and should never be overlooked when asystem of this type is installed.VVVVV..... PLANT ST PLANT ST PLANT ST PLANT ST PLANT STARARARARART-UPT-UPT-UPT-UPT-UP Start-up of a wastewater treatment system must becompleted before it will provide the results intended.Although a treatment plant is selected for a particularapplication and accessory elements are added to enhanceits operation, it must be adjusted andeach element must be set to functioncorrectly for the particular conditionsexisting in the facility it is serving.Plants may be properly sized andaccessory equipment may have theproper capacity but unless eachelement is adjusted to suit thesituation, the equipment will very likelynot do its job as well as intended.

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Aeration rates, sludge return rates and mixing velocitiesmust be adjusted within the system to provide the bestpossible treatment results. Chlorination stations must applyjust the right amount of chlorine at the right time to providethe disinfection required. Tertiary filters must be dosed withthe proper volume of effluent to provide optimum filtration.Lift stations must be adjusted to automatically dose at levelsthat will not surcharge other elements of the treatmentfacility and at intervals that will not cause unnecessary wearon the pumps and related equipment. These items andmany others like them must be considered during start-up.Each individual element of the facility must be adjusted toenable it to provide the best possible results. Norweco distributors spend a great deal of time and moneyin the care and start-up of a plant. They adjust the equipmenton a bi-weekly basis for the first eight to twelve weeks ofplant operation to insure that all phases of start-up have beencompleted. The operator must understand the role theseadjustments play in the operation of the system and recognizethe various conditions that may be encountered. The first thing that must be accomplished during start-up of a wastewater treatment facility is the properadjustment of all mechanical equipment. Blowers shouldbe rotated by hand several times to insure that they willturn freely. Then the weight and cap on the pressure reliefvalve should be removed and the blower switch turned on.If the blower is running in the proper direction, air will bepushed out of the pressure relief valve. If the rotation isbackwards, air will be drawn in the valve and it will benecessary to reverse the rotation of the motor. To do this,remove the electrical cover from the motor and reverse themotor leads as shown on the wiring diagram inside thecover. Be sure to shut off electrical power to the system atthe master control box before working on the motor. Related mechanical equipment such as comminutors,pumps and others should also be checked before beingplaced into operation.ELECTRICAL EQUIPMENT

Electrical controls for the systemmust be checked and set before thesystem is placed into operation. Shutoff the main disconnect at the powersource before testing or setting any ofthe individual electrical controls. Turn all switches to the “Automatic”or “On” position. Set the time clock tothe proper time of day. The initial timeclock setting should be fifteen minuteson and fifteen minutes off. There areninety-six individual trippers on the dialof the time clock and each tripperindicates fifteen minutes of operationin the daily cycle. Be sure to extendevery other tripper around the entirecircumference of the clock dial toinsure that the plant will have a

constant fifteen minute cycle throughout the day. Thissetting should not be altered until the daily and weeklyloading of the facility is established.SLUDGE RETURN The airlift sludge return system is used to pump settledsludge out of the hopper in the settling tank and back to theaeration tank to complete the treatment process. Duringinitial start-up of the plant the sludge return should be set

to operate at maximum capacity. Completely open the airsupply valves on the sludge return and check to see thatthe large valve in the horizontal sludge return line is open.Norweco sludge returns are capable of pumping in excessof 200% of the daily flow. Although the wide open setting isused initially it should be reduced as soon as the plantbegins to develop solids and normally will be adjusted tooperate at a considerably lower level.SURFACE SKIMMER A surface skimming system is provided with eachNorweco sewage treatment system. They are provided toremove floating particles from the surface of the final settlingtank and return them to the aeration chamber of thetreatment plant. Skimmers are useful maintenance tools,but are not considered a standard part of the system andshould not be in operation continuously. Norweco skimmershave an adjustable plastic inlet fitting that is set level about1/8 of an inch under the surface of the final settling tank.They operate on an airlift principle and draw off a thin layerof liquid from the surface of the tank. This draw off createsa minor up-flow in the tank and, if the skimmer is allowed tooperate continuously, the settling function of the final tankwill be reduced. Therefore, surface skimmers should onlybe turned on for short periods of time, as required, to removeany material that has accumulated on the surface. Thisshould be done on a daily or weekly basis. The exactfrequency should be determined by daily inspection of thesurface. Operators must remember that skimmers are nota standard part of the system and, therefore, should not becontinuously in operation.FOAM SPRAY SYSTEM Foam control spray systems are provided on all largerinstallations and most of the smaller ones, especially if theplant is expected to be underloaded or if it is to receive ahigh detergent flow. Foam spray devices, like surfaceskimmers, are a handy tool and may be used for routineplant maintenance and elimination of a nuisance. The presence of foam in an extended aeration plantindicates that the organic loading of the system is low. Anextremely high detergent flow may also cause foamingalthough this is not normally the case. Most sewagetreatment systems develop foam during their initial start-upbecause the solids level in the plant is lower than intended.Usually this foaming will subside after several weeks - oncethe solids level in the plant comes up to the anticipated level. Foam in a plant that has been in operation for sometime normally indicates loss of solids or lack of solids cominginto the plant. The foam itself has no effect on the operationof the system or its ability to treat the wastewater. However, if it develops in relatively large quantities itmay become a nuisance by accumulating on tank walls,piping and possibly even coming out the top of the tank.For this reason, a foam control spray device is provided. The foam spray pump is installed in an isolated sectionof the settling tank and it pumps clear liquid back to a seriesof spray nozzles located above the surface of the aerationchamber. A wash water outlet is installed above thedischarge of the pump so that the spray nozzles may beshut down and the outlet may be hooked up to a hose andopened to provide wash down water for the plant. Like thesurface skimmer, the foam spray system should not be inoperation on a continuous basis. It should be placed intooperation only when it is needed for wash water or whenfoam accumulates to a level where it becomes a nuisance.

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HOPPER MAINTENANCE Final settling tanks in the treatment plant are designedto remove activated sludge and organic material from thecontents of the plant. They are, as their name indicates,settling chambers where the tank contents are held aboutfour hours to permit all solid material to settle to the bottomof the chamber. The lower area of the tank is designed toform a hopper. Sidewalls are slanted into the center of thetank to provide a small area where the sludge willaccumulate. Here the settled sludge is picked up by theairlift sludge return pump and pumped back to the aerationchamber for final treatment. Activated sludge in the plant has a tendency to be stringyand sticky during its initial development. Once it reaches alevel of maturity it is relatively easy to settle and separatefrom the liquid. Because of its sticky characteristics initiallyit does not do a good job of settling in the hopper portion ofthe tank and it is necessary to gently scrape the hoppersidewalls with a squeegee. Plant hoppers should bescraped at least daily during the start-up phase of operation.Several weeks later when the solids level in the plantreaches maturity it may be possible to scrape the hoppersat less frequent intervals. This, however, should bedetermined by observation of the plant. Although scrapingmay be required at less frequent intervals the hopper shouldnever be left unscraped for longer than a week.DIFFUSERS (Mixing Rates) It is necessary to continuously mix the contents of theaeration tank with the incoming raw sewage to insure thatthe activated sludge within the system is brought intoconstant contact with the incoming sewage. The amountof air being introduced and the distribution of the air alongthe sidewall of the tank will determine the degree of mixingwithin the aeration chamber. Individual diffuser bar assemblies must be “balanced”to aerate evenly with other diffuser bars in the tank. To“balance” the mixing rate adjust the individual air controlvalves on each drop pipe leading to the individual diffuserbars. Do not use the control valves to reduce the amountof air being introduced! Air reduction should beaccomplished separately by adjusting the time clock.Remember, individual air control valves should be usedonly for minor adjustments. Each air control valve on the air header should be placedin the open position when the plant is first started. Observethe surface of the aeration chamber and the roll of thecontents to determine if individual diffusers are getting toomuch air or not enough. Where the mixing is most violentthe air valves should be turned down until even mixing isobtained. Before doing this be sure that the air valves inthe area where mixing is least active are completely open.Adjustment of the individual valves should be made at thetime of equipment start-up so the tank roll is even alongthe length of the aeration chamber. After this has beendone the actual aeration rate may be established.CYCLE OF OPERATION Twenty-four hour time clocks are used to cycle operationof the equipment and obtain proper aeration rates. Theplant time clock has ninety-six individual tripper prongs andeach prong represents fifteen minutes in the overall twenty-four hour period of operation. Initially it is set to operatefifteen minutes on and fifteen minutes off. This is just atemporary setting - in most cases the time cycle will be

adjusted during the bi-weekly visits so that optimumtreatment may be obtained. For example, in the case of atreatment facility serving a school, the unit may begin torun continuously in the early morning (4:00-5:00 A.M.) andrun nonstop through 7:00-8:00 P.M. Then intermittentoperation may be continued throughout the night at fifteenminutes to a half hour out of every hour. Secondary orweekend time clocks may also be employed to switchcontrol over to another unit that will change the aerationrate. The ultimate time cycle and aeration rate must bedetermined by working closely with each individual systemand adjusting it to best serve its particular facility. Somesystems may have changing flows and not reach theirultimate cycle for months or, in some cases, even years. Ifthis is the case it is especially important to observe andadjust the aeration rate as required by the wastewater load. Individual adjustment of each element in the wastewatertreatment facility must be based on the performance of theplant during the start-up cycle.VI.VI.VI.VI.VI. PLANT OPERA PLANT OPERA PLANT OPERA PLANT OPERA PLANT OPERATIONTIONTIONTIONTION An Extended Aeration Wastewater Treatment plant ismade up of two basic elements and a third element, pre-treatment, is normally added. There are also a number ofaccessory items that may be employed but the basicelements must always be installed to provide adequatetreatment. The added element, pre-treatment, is the first devicethe sewage enters. Pre-treatment may be provided by usinga trash trap (holding tank), comminutor (sewage grinder)or a bar screen (sewage straining device). Any of theseelements may be employed - they are all designed toaccomplish the same task. That is, to pre-treat or conditionthe wastewater before it enters the aeration chamber ofthe treatment plant. Trash traps are holding tanks that are designed to trapfloating material and they have a space at the bottom sothey will trap solid material before it enters the aerationtank. Normally they are sized to provide about 15% of therated treatment plant capacity. Comminutors are sewage grinders that shred the solidmaterial in the raw wastewater flow into small particles.They are equipped with an electric motor and hardenedsteel cutters that reduce the solids in size as they passthrough the comminutor. The third type of pre-treatment device is a bar screen.It is made up of a series of bars arranged in parallel to traplarge objects that may be in the wastewater flow. Barscreens are usually installed with a comminutor to protectit from large untreatable or metal objects that might damagethe cutters. Bar screens may be used by themselves,however, they require manual cleaning and disposal of thescreenings on a daily basis. Because of this maintenancefactor they are normally not used alone. Aeration is the next step in the treatment process.Incoming wastewater enters the aeration chamber whereit is held for twenty-four hours. During this period the organicmaterial is intimately mixed with the activated sludge andoxygen is introduced to support the life of the bacteria. Thebulk of the organic elements are eliminated in this chamberin the first three to five hours, the remainder of the twenty-four hour period is used to oxidize the remaining organicmaterial and to eliminate excess activated sludge produced.

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Final clarification (settling) is the third stage in thetreatment process. After being aerated for twenty-four hoursthe liquid flows into the settling chamber where it is heldabout four hours. The settling tank is a still chamber thatallows the activated sludge and organic material to settleto the bottom. Only clear, odorless liquid is left at the top ofthe system where it can be discharged from the plant. Whenthe sludge settles to the bottom it is pumped back to theaeration chamber by an airlift pump. This pumping actionsupplies a constant flow of activated sludge to the incomingraw sewage and returns the partially treated particles tothe aeration chamber for final treatment. Plant operation on a day to day basis is primarily a goodhousekeeping policy that insures all equipment is kept cleanand operational. Plant odor and appearance usually tell whatresults are being obtained. A good chocolate brown color inthe aeration chamber, no odor and at least twelve inches ofclear water on the top of the settling tank indicates goodoperation. This is a general guideline and actual treatmentresults must be obtained by testing the plant effluent (see the“Testing and Evaluation” section of this manual). Visual inspection of the effluent is another fast way toevaluate the performance of the system. Effluent shouldbe clear and odor free and should not contain anysuspended material. Evaluations based on the appearanceof the system and its effluent may be easily determined bya seasoned operator who is familiar with the conditionsand performance of the plant.OVERLOADING Some wastewater treatment plants receive morewastewater than they were intended to treat. They may behydraulically overloaded or organically overloaded.Obviously the best solution for adjustment of a plant that isoverloaded is to expand it to a point where it is capable ofhandling the extra load. Although extreme overloadingmakes expansion of the facility a necessity, manywastewater systems are overloaded and are adjusted toprovide respectable treatment results. If the plant is notoverloaded to a large degree it may be adjusted to introducemore oxygen and return more sludge. An organic overloadmakes it necessary to supply more oxygen and mixing. Itmay even require installation of an aerated sludge holdingtank and drying beds to dispose of excess sludge. On theother hand, hydraulic overloading is nothing more than toomuch liquid going through the system. It causes a washout of the activated sludge and reduces the retention in thesettling tank to a point where it is unable to adequatelysettle out the solids. Hydraulic overloading may beeliminated by adjusting the sludge return to obtain moresettling. If either type of overload is too great it will beimpossible to correct and expansion of the system will bethe only solution. All Norweco systems have a built in safetyfactor to enable them to handle reasonable overloads.UNDERLOADING Most wastewater treatment plants, at one time or another,will receive less organic material or liquid flow than theywere originally designed to receive. Usually the underloadis nothing more than a low flow period from the sewagesource. But, in some cases, it may be caused by anunintentional underloading of the system. For example, amobile home park may plan to ultimately serve 200 units,the full size system may be installed and yet it may be oneor even two years before the park is fully developed. During

this period the facility may be underloaded, that is it maynot receive the flow it was designed to handle. This type ofunderloading may be a nuisance because of foaming in theaeration chamber and the sludge may be stringy and sticky.Usually an underloaded system can be adjusted to providesatisfactory results. The aeration rate and time cycle of theplant should be reduced and constant use of the squeegeeto scrape the hopper will probably be necessary. In most situations underloading is only a temporaryproblem and the sewage flow will change. For this reason,it will be necessary to observe the operation and appearanceof the system and readjust its individual elements to bringthe plant operation up on a progressive basis.SLUDGE PROBLEMS As stated before, the purpose of the final clarificationtank is to settle out and separate the solids that pass throughfrom the aeration tank. To accomplish this the contents ofthe clarification chamber must remain relatively still. Sludgein a newly started or underloaded system may be stringyor sticky. As it settles to the bottom of the clarificationchamber it may accumulate on the sidewalls and slantedwalls of the hopper. If the sludge is not soon removed it willbuild up and become a semi-solid mass that will fill thelower portion of the hopper. When this happens the masswill stop the normal movement of sludge and gas will beginto form. As the gas builds up it will float chunks of sludge tothe surface where they will accumulate as a scum layer.To eliminate this problem the plant hoppers should bescraped every day during the first few weeks of operation.The hopper begins about three to five feet below the surfaceand it should be gently scraped in a slow, easy, downwardmotion to help move the sludge toward the bottom where itwill be picked up by the sludge return pump. Care must betaken not to stir up or agitate the sludge because it mayfloat to the surface. If this happens, the sludge must bedipped out and placed back into the aeration chamber. In addition to sludge build-up there may be otherassociated conditions that need attention. For example, asludge return may be discharging clear liquid while there issludge in the bottom of the hopper. This can happen if softsludge is allowed to pack in the bottom of the hopper exceptfor a narrow channel that runs down through the sludgemass to the pump intake. Clear liquid from the surface willbe pulled down the channel and through the pump withoutdisturbing the sludge mass. For this reason a visual checkof the sludge return may not be sufficient and slow gentlescraping with the squeegee may be necessary. Another possible condition is a plugged sludge return.When the sludge return is adjusted to pump less than 1/3of a pipe full it may allow sludge to pack around the bottomof the hopper and pump intake. If this happens the sludgemay build up inside the pump tube until it completely stopsthe pumping action. This problem may be corrected bybackwashing the sludge return. Backwashing is a simple operation where the air andsludge flow are forced out the inlet end of the pump.Procedures for backwashing the sludge return are given inthe “Sludge Return” section of this manual. Caution:Backwashing stirs up the liquids in the tank and increasesthe solids level near the surface! For this reason, airliftsludge return pumps should not be backwashed unlessthey are completely plugged and cannot be reopened byincreasing the return rate.

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Dirt and mud from backfilling around the tanks shouldnever be allowed to enter the system. If mud gets in it willmix with the sludge and form a heavy, solid, sludge mass.The sludge return pumps will not handle heavy mud - itmay completely clog the airlift. To determine if mud has entered the system place theend of the squeegee into the bottom of the hopper. Gentlylift it back out and check the edge of the blade for mud. Itsdepth and density may be determined in the same manner.If mud has entered in any quantity it will be necessary topump the tank and remove the mud from the hopper. If mud enters the system special care must be taken toinsure that air lines are not clogged. If mud enters the airlines the operator must remove and clean the air piping.Remember to readjust all air valves after doing any service.EVEN AERATION All plants must be adjusted to provide even aeration(mixing) of the tank contents. This is done by “balancing”the air flow of individual diffuser bar assemblies until themixing is even throughout the aeration chamber. Eachdiffuser bar assembly has a separate air control valve thatmust be adjusted to balance the air flow. Even mixing must be maintained to insure that shortcircuiting of the sewage flow does not occur and that nosludge accumulates in the bottom of the aeration chamber.An even aeration rate will keep all sludge in constantsuspension and will constantly bring the organic materialinto contact with the activated sludge. Providing an even,circular mixing pattern will also reduce the possibility thatsewage may enter the clarification chamber before it hasbeen retained in the aeration tank for a sufficient period oftime. Although the wastewater flows from one end to theother in the aeration tank, in reality, it will flow in a spiralpattern and be retained for a considerable length of timebefore getting to the outlet end of the aeration tank.SLUDGE RETURN The sludge return is an airlift pumping device that usesair produced by the blower to pump settled sludge back to

the aeration chamber. Individual airliftsare equipped with air control valves topermit adjustment of the pumping rate.Liquid sludge valves are also providedand should be left in the full openposition unless the operator isbackwashing the system. Sludge returns should be inspecteddaily to insure that they are returningat least 1/3 of a pipe full. This is theminimum amount that can be pumpedwithout increasing the chance ofplugging the airlift. Any adjustmentabove 1/3 full may be used if itimproves plant operation. Sludge returns may becomeplugged if the hopper has not beenproperly maintained. When thishappens the airlift sludge return mustbe backwashed. To backwash thesludge return first adjust the air supplyvalve to the full open position. Nowshut off the liquid sludge valve in thehorizontal line of the sludge return.

This will force air out of the intake end of the pump andblow out any stoppage. If backwashing does not work itmay be necessary to supply additional air by shutting offother air supply valves in the plant. Do not use this methodunless normal backwashing fails. Be sure to adjust all airand sludge valves back to their original position oncebackwashing has been completed. A constant return of activated sludge to the inlet of thetreatment plant is an important function in the operation ofthe system. This constant pumping of sludge improves thecontents of the settling tank by removing solids and providesa constant supply of activated sludge to incoming sewage. Inspect the sludge return rate and condition of the sludgebeing returned on a daily basis. If the sludge is held in thebottom of the hopper too long it may loose its chocolatebrown color and appear dark or in extreme cases evenblack. If this condition exists, increase the sludge returnrate and step up the scraping schedule of the hopper sothat the sludge will not remain in the bottom of the settlingtank too long. If the returned sludge is light or clear itnormally indicates that it is not being returned as it shouldbe and is accumulating in the settling hopper. Increase thefrequency of scraping if this occurs.SURFACE SKIMMER Surface skimming devices are provided as a standardpart of each Norweco system. Although they are notrequired they are a very handy maintenance tool and shouldbe used on a regular basis. Like sludge returns, skimmers operate on the airliftprinciple. They are used to draw floating material off thesurface of the settling tank and return it to the aerationchamber. Norweco skimmers are equipped with anadjustable plastic intake that is set 1/8 of an inch under thesurface of the water. Skimmers should not be usedcontinuously. They should only beturned on when necessary to removefloating material from the surface ofthe clarifier. Once the surface is cleanthey should be shut off until morematerial has accumulated on thesurface. Occasionally a skimmer maybecome clogged. If this happens itmust be backwashed just like asludge return. To backwash thesurface skimmer, shut off the air supply valve and removethe plug at the top of the tee in the vertical airlift assembly.Inflate a plumber’s stopper below the tee in the airlift line.Be sure to place a cover over the skimmer inlet because itwill force liquid out the intake and it may spray up into theair a short distance. The easiest way to do this is to placea sheet of plywood on top of the grating above the skimmerinlet. Next open the skimmer air supply valve to the fullopen position. Any stoppage should be blown out the intakeof the skimmer line by the reverse air flow. Now shut theair off again and remove the plumber’s stopper. Replacethe plug in the top of the tee and readjust the air supplyvalve. If the backwashing was successful the skimmer willresume normal operation. If not, the stoppage may be insome other portion of the line and it will be necessary toclean out the skimmer lines.

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FOAM SPRAY SYSTEM Spraying systems to control foaming in the aerationchamber are usually installed with extended aeration sewagetreatment plants. They consist of a spray pump mountednear the surface of the final clarification chamber and a seriesof piping and spray nozzles arranged above the surface ofthe aeration chamber. The pump draws clear liquid out ofthe settling chamber and sprays it down on the surface ofthe aeration chamber to knock down the foam before it hasan opportunity to accumulate. Norweco spray pumps are

wired into the controls of the blower sothey operate only when the blower isrunning. However, they can becontrolled manually to simplifymaintenance of the plant. Foam spray systems should not bekept in operation unless foaming in theplant is creating a nuisance. A washwater outlet is installed at the top ofthe pipe coming up from the spraypump. It is there to provide hose downwater for sidewalls and piping in theplant. A valve is installed between thewash water outlet and the spray

nozzles so the operator can shut off the liquid flow to thenozzles and supply additional water to the outlet forwashdown purposes. Norweco spray nozzles are machined from solid brassand have a tapered orifice to reduce clogging. Manyoperators use the wash water outlet and hosing facilitiesmore often than the spray system. Like the surface skimmer,spray systems should not be used except when necessary.Foam on the surface of the aeration chamber indicates lightloading of the plant or a lack of solids in the plant. However,if the foam is not creating a nuisance it is not necessary toeliminate or reduce it by utilizing the spray system. Chemical defoaming agents are available but they areexpensive and not recommended for general use. Iffoaming becomes a problem in a plant that does not havea foam control pump it is generally more economical toinstall a spray system than it is to purchase defoamingagents and related chemical feed equipment.POWER FAILURES Although electrical power should be supplied to the planton a continuous basis there may be an occasional powerfailure caused by lightning or a break in the line. When powerhas been off to the plant or any element within the plant theelectrical controls should be individually checked. First, checkthe main fuse box at the power source. Replace any of thefuses that appear to be blown. If the equipment does notresume operation when this has been done the individualelectrical controls must be checked. Replace the fuses thatappear to blown, reset the breakers and push the reset buttonon each of the starters. If the equipment does not resumeautomatic operation contact your Norweco distributor.VII.VII.VII.VII.VII. PLANT MAINTEN PLANT MAINTEN PLANT MAINTEN PLANT MAINTEN PLANT MAINTENANCEANCEANCEANCEANCEPRE-TREATMENT When a bar screen is used for pre-treatment it must becleaned at least once a day. Norweco bar screens areequipped with overflows, and will continue to pass sewageeven if they are clogged. However, it is important to insurethat they are kept clean at all times. Therefore, the operatorshould clean the bar screen at least once a day and dispose

of any screenings that have accumulated. Screenings maybe disposed of by burying them or storing them in a sealedcontainer for pick-up by a sanitary disposal service. When a comminutor has been provided for pre-treatmentthe cutters should be cleaned daily to insure maximumefficiency. Check the cutting efficiency and lubricationsystem once each month. The number of hours it has beenin operation and the care it has received will determine ifand when an overhaul is needed. Do not open thecomminutor for inspection of internal parts unless there isdefinite evidence of internal trouble. The rotor assemblymay be removed for inspection or cleaning. If the comminutor becomes noisy or begins to vibrate itmay indicate improper adjustment of the cutters. It mayalso indicate a worn bearing in the unit or a worn gear inthe gear box. If the cutters are clean and free of debris andthe operation is noisy or vibrating, contact the local Norwecodistributor for service. When a trash trap is used for pre-treatment it should bechecked at least twice a year. Remove the inlet and outletcovers to be sure nothing is obstructing the flow in and outof the tank. Do not clean them unless the sludge or scumlayer is within three inches of the bottom of the outlet tee. The sludge layer thickness can be measured with theplant squeegee or any device that can be used to feel outthe bottom of the scum mat. Force the squeegee downthrough the mat and raise it until resistance from the bottomis felt. The distance to the bottom of the outlet device canbe found with the same tool. A rough white towel wrapped around the squeegeehandle and lowered into the bottom of the tank will showthe depth of the bottom sludge layer. Lower it behind theoutlet baffle to avoid scum particles. Wait several minutesand carefully remove the squeegee - the sludge depth willbe shown by the particles clinging to the towel. Never wash the tank or use disinfectant on the insideafter the trash trap has been cleaned. Do not try to improveoperation of the trash trap by adding a disinfectant orchemical. Although some products are sold to clean oractivate trash traps, most contain chemicals that causesludge bulking and increase the alkalinity within the tank.AERATION Mixing in the aeration chamber should be inspected daily.To check the mixing, simply observe the top surface of thechamber to see if air is rising evenly along one side andthe tank roll is constant and evenly distributed. Also checkthe daily cycle on the time clock at least once a week tosee that it is set to the proper time of day. “Evenair” diffuser bars should be removed and inspectedonly if the mixing in the tank is uneven. It may be possibleto correct uneven mixing by adjusting individual valves onthe air header. This should only be done to balance the airflow. It should not be necessary once the plant is inoperation unless someone has readjusted the valves. Ifthe mixing is uneven and the valves are properly adjustedthere may be a stoppage in one of the air lines or diffuserbars. If so, they should be removed and cleaned. If a foam spray system has been provided, the nozzlesshould be checked weekly to be sure they are not clogged.This routine check will not be necessary after plant start-up unless the spray system is being used. Individual air valves should be checked for leaks twicea year. To check a valve for leaks, simply spray it with alight coat of leak detector.

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The aeration chamber should also be checked andcleaned on a regular basis. Sidewalls above the liquid levelshould be hosed down every week or as required. Thecolor and odor of the chamber should be inspected daily.Daily observation by a qualified operator will enable him toquickly evaluate the condition of the system.SETTLING Inspect the sludge return daily to see that it is returningat least one-third of a pipe full. Also check the surfaceskimmer inlet adjustment and return rate on a daily basis.The skimmer inlet should be set 1/8 of an inch under thesurface and the return rate should be at least 1/3 of a pipefull. Turn the skimmer on if floating solids have accumulatedsince the previous day. Let it run long enough to collectand return the floating particles to the aeration chamberand then shut it off. Inspect the effluent weir weekly to see that it is level andskimming along both surfaces. Use the squeegee providedwith the plant to scrape the hopper in the lower portion ofthe settling tank. This should be done each day unless visualinspection of the plant permits less frequent scraping. Neverallow the hopper to go unscraped for longer than one week. The inlet screen on the spray pump should be inspectedand cleaned twice a year. If the spray system is not in use,this item should be omitted from the maintenance schedule.CORROSION PROTECTION All metal surfaces on the plant and accessory equipmentshould be wire brushed and painted as required. Operatorsshould go over the entire system and touch up paint onceeach year.VIII.VIII.VIII.VIII.VIII. SPECIAL INSTR SPECIAL INSTR SPECIAL INSTR SPECIAL INSTR SPECIAL INSTRUCTIONS fUCTIONS fUCTIONS fUCTIONS fUCTIONS forororororTRATRATRATRATRAVVVVVALAIR™ UNITALAIR™ UNITALAIR™ UNITALAIR™ UNITALAIR™ UNIT Norweco Travalair™ wastewater treatment plants aredesigned to automatically collect the settled sludge in thehopper of the final clarification chamber. The Travalair unitmoves automatically from end to end scraping the hopperand, at the same time, a surface skimming system installedas an integral part of the Travalair unit, continuously andautomatically cleans the surface of the tank. A squeegeeis connected to the lower portion of the Travalair unit and itscrapes the slanted sidewalls of the hopper to eliminatesludge in the bottom of the tank. This exclusive featureeliminates daily hopper scraping as required withconventional systems. The drive unit for the Travalair system is mounted onthe Travalair unit and travels on the track connected to thetop of the treatment plant. The scraper blades and skimmer

inlet fittings of the Travalair unit areadjusted during the initial installationand it should not be necessary toreadjust them after the system hasbeen placed into operation. The air supply valves for theindividual sludge return and surfaceskimmer systems should be adjustedso that each airlift is pumping at least1/3 of a pipe full. Individual liquid

sludge control valves are provided for the skimmer andsludge returns. They should be used for backwashing anyof the individual airlifts whenever necessary. The air supply and power hose reels located at oppositeends of the track are maintenance free and require noperiodic maintenance or lubrication.

The Travalair mobile unit is motor driven and with theexception of periodic lubrication it requires no maintenance.Fill the gear box on the gear motor twice a year with 90weight gear lube. Bearings in the gear motor areprelubricated and sealed and require no further lubrication.The wheels on the mobile unit and both drive wheelsunderneath it should be lubricated once a month. Thereare two grease fittings on the drive bar and one for eachwheel on the unit. Use a grease gun and good gradelubricant (GED6A2C5 or equal) to refill all six fittings at thirtyday intervals. Tension on the drive wheels may need to be periodicallyadjusted. To determine if additional tension is necessary,inspect the tension spring under the adjustment handle atthe back of the mobile unit every thirty days. The tensionspring should be depressed 50% to insure adequate tension. End walls in the hopper are not scraped by the Travalairunit. For this reason, they have been designed with a muchsteeper angle so that sludge will not accumulate on them.Plant operators should use the squeegee to scrape bothend walls in the tank at least once a week.IX. MECHANICAL EQUIPMENTIX. MECHANICAL EQUIPMENTIX. MECHANICAL EQUIPMENTIX. MECHANICAL EQUIPMENTIX. MECHANICAL EQUIPMENTMAINTENMAINTENMAINTENMAINTENMAINTENANCEANCEANCEANCEANCEBLOWERS Positive displacement blowers are used to supply air tothe individual elements within the treatment facility. Theblowers contain two impellers mounted on parallel shaftsand they rotate in opposite directions. As one impellerpasses the inlet of the blower, it traps a quantity of air andcarries it around to the outlet where it is discharged. Timinggears are installed on the end of each shaft to regulate theposition of the impellers and maintain the clearances theyneed to insure maximum efficiency. Always be sure thepulley on the blower is properly aligned with the motor pulleyso that no undue stress or wear is placed on the blower.MOTORS Electric motors are used to drive the individual blowerunits. When they are well maintained they normally do notrequire repair. However, if a problem does develop with amotor, fast, dependable service can be obtained from thelocal Norweco distributor. All dust should be cleaned awayfrom the ventilating openings in the motor shell at leastonce a month. At the same time be sure to check the pulleyon the motor shaft to see that it is aligned with the blowerpulley and properly tightened.AIR FILTER An inlet air filter/silencer is installed on each blower unitin the treatment plant. It is installed on the inlet of the blowerto filter the air and trap foreignobjects that might enter theblower. To enable the blowerto produce the air intended,the filter must be kept cleanat all times. Check the filterelement once a month andclean it as necessary. The best way to clean anair filter is to purchase asecond one and rotate operation of the filters. This willpermit the operator to install a clean filter and keep theplant in operation while the dirty element is soaked inkerosene and cleaned.

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PRESSURE RELIEF VALVE A pressure relief valve is installed in the air dischargepiping of the mechanical unit. The relief valves are weightedtype valves that lift up to discharge air if the pressure in thesystem becomes too great. The proper number of weightsare placed on the system when it is installed and they shouldnot be removed or changed. Remove and oil the inside ofthe relief valve cap once a month to insure free operationof the valve.AIR VALVES Inspect the air valves in the treatment plant daily to besure they are properly adjusted. After the plant andequipment is adjusted and running as intended each valvein the system should be marked so that it is easy todetermine if the valves are correctly set.DIFFUSERS “Evenair” diffuser bars in the treatment plant should beinspected once a year. Disconnect the union at the top ofthe individual air drop pipes and lift out the entire assembly.Check to be sure that all fittings are in place and properlytightened and that each air opening in the diffuser assemblyis clean and free of any foreign material.SLUDGE RETURN Inspect the airlift sludge return daily to be sure it is returningat least 1/3 of a pipe full. Any return rate above the one-thirdmark may be used if it improves operation of the plant. Sludgereturns should pump continuously - the plant should neverbe in operation unless the sludge return is operating.SURFACE SKIMMER Check the skimmer inlet fitting weekly to see that it isset level 1/8 of an inch under the surface of the water. Itshould not be set deeper because it will pump too muchliquid and be less effective. Skimmers should return onlyabout 1/3 of a pipe full. Turn them on long enough to removesolids from the surface of the settling tank but do not letthem run on a continuous basis.FOAM CONTROL SPRAY SYSTEM The spray system should be inspected weekly to insurethat all equipment is operational. Check the spray pumpfirst, turn the pump selector switch to the “Hand” position.All of the spray nozzles should begin spraying. While theyare on, inspect them individually to be sure they are notclogged. Remove and check the pump inlet strainer onceevery six months. If the spray system is not in use omitthis item from the maintenance schedule.EFFLUENT WEIR The final effluent weir in the settling/clarification chamberof the treatment plant should be cleaned each day. Anysludge or grease particles that have accumulated alongthe edge of the effluent weir should be removed with thesqueegee or a dip net. The degree of settling obtained inthe clarifier is, to a large degree, dependent upon the sizeand adjustment of the weir. Inspect the weir at least oncea week to be sure that it is level and skimming evenly alongthe entire length on both sides. To adjust the weir, loosenthe bolts on the side of the weir plate. It is not necessary topump the tank down or use special tools for this adjustment.Once a year the weir should be wire brushed and paintedas required.

V-BELT & PULLEYS Pulleys on the motor and blower connected by a v-beltare used to drive the unit and provide the air required forthe treatment process. The pulleys should always be keptin perfect alignment to eliminate unnecessary wear on thev-belt and bearings. To check the pulleys for alignment,place a straight edge against the front face of the motorpulley and let it extend over and against the front of theblower pulley. Slide the straight edge down so that it isresting on top of the motor and blowershaft. If the pulleys are properlyaligned the straight edge will touch allfour points along the front face of thepulleys. If they are improperly alignedthey can be adjusted by loosening themounting bolts on the back of themotor and shifting the motor until theyalign. Check the pulleys for properalignment once a month and, at thesame time, inspect the v-belt for wear.Once a week check the v-belt to insurethat it is not slipping. To do this, shut the motor off and letthe unit come to a complete stop. Now turn the unit onmomentarily. If the v-belt is loose, the blower pulley will notbegin to turn until after the motor pulley has turned severalrevolutions. If this happens the motor mounts must beloosened and the motor must be moved away from theblower to obtain more belt tension. Naturally, when this isdone it will be necessary to recheck the pulleys for properalignment. Most plant operators find it convenient to keepa spare v-belt on hand so they can replace the belt whennecessary without interrupting operation of the plant. Onespare belt is supplied with each Norweco system and itshould be kept in a convenient place for the operator. Newv-belts have a tendency to stretch slightly and wear duringthe first few weeks of operation. Therefore, operators mustalways check for v-belt slippage in any new system.WASH WATER SYSTEMS Norweco plants that are equipped with foam controlsystems have a wash water outlet located on the dischargepiping of the spray pump. The foam control spray pump islocated near the surface of the final tank and has a verticaldischarge line that runs near the top of the treatment tank.At this point it turns and goes through the wall to the aerationchamber and spray nozzles. Thewash water outlet is installed near theelbow where the vertical pipe turns toenter the aeration tank. A conventionallawn or garden hose may be hookedto the outlet and a shut off valve isprovided between the outlet and thespray nozzles so the liquid flow mayall be diverted to the wash watersystem. Most plant operators find itconvenient to connect a garden hose to the wash wateroutlet and use it daily to hose down the tank walls, piping,baffles and other elements within the system. When thespray system is not in use it is still possible to wash thesystem by turning on the spray pump and shutting off thevalve to the spray nozzles. Plant operators shouldremember that liquid obtained from the wash water outletis partially treated wastewater and should not be usedexcept for internal cleaning purposes. It is not potable waterand must not be used for anything except routine hosing ofplant components.

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SLUDGE HOLDING TANKS Sludge holding tanks are used when the level of solidsin the aeration chamber gets too high. Holding tanks areprovided only as a temporary holding facility to retain excesssludge during high flow periods. Sludge may be divertedfrom the return sludge line to the sludge holding tank byshutting off the valve in the normal sludge return line andopening the valve on the auxiliary piping leading to thesludge holding tank. Be sure to open the valve on theauxiliary piping before closing the valve on the normalsludge return line. If the valves are not opened and closedin this manner the entire sludge flow will be shut off for ashort period of time and will cause the airlift to backwash.

As mentioned before, backwashingstirs up the settling chamber andshould not be done unless required toopen an airlift line. Sludge holding tanks may beinstalled as aerated or non-aeratedtanks. Aerated holding tanks haveauxiliary piping from the air header ofthe treatment plant proper as well asthe sludge return. When this is thecase, be sure the aeration of the sludge

tank is well distributed and keeps the tank contents inconstant suspension. Non-aerated sludge holding tanksshould be checked once a month to determine if the levelof sludge within the tank is too high. When the sludge in anon-aerated holding tank fills more than 1/2 of the chamber,the tank should be pumped. The sludge level within thetank may be determined by probing with the squeegee.STAND-BY UNIT Stand-by mechanical equipment is provided on all largetreatment plants and in many cases, the smaller ones aswell. Norweco stand-by equipment is a complete secondset of motors, blowers and electrical controls supplied toprovide a duplicate set of equipment for operation in caseof a mechanical or electrical failure. Plant operators shouldperform maintenance on the stand-by equipment at thesame intervals specified for the primary unit in the treatmentplant. Most systems are wired to alternate automaticallyand it is generally accepted that the best way to obtain longequipment life is to permit the units to alternate operation.COMMINUTORS Daily care for a comminutor is outlined in the “PlantMaintenance” section of this manual. In addition, they mayoccasionally require mechanical maintenance. Normally, itis most economical and convenient to have the mechanicalmaintenance performed by a Norweco distributor. Monthly inspections of the cutting efficiency andlubrication system should be made. Lubrication is coveredseparately in the “Lubrication” section of this manual.Occasionally a comminutor will require a complete overhaulbut this should not be attempted by anyone other than aNorweco distributor unless they have had prior experiencewith the equipment. The operator should not open thecomminutor for inspection of internal parts unless he is surethe trouble is inside the unit. The rotor assembly may beremoved for inspection or cleaning. Plant operators should clean the cutters daily and adjustand sharpen the stationary and rotating cutters as needed.

To adjust the stationary cutter proceed as follows:1.Remove the rotor assembly.2.Rotate the screen by hand until one rotating cutter

edge engages the stationary cutter.3.Insert a feeler gauge in the vertical space between

the cutter bar and the edge of the stationary cutternearest the rotating screen. This space should not bemore than 0.002 inches.

4.Loosen the socket head screws on the bearinghousing arm until they are finger tight but the cuttershould not move freely.

5.Insert the 0.002 inch feeler in the upper vertical spacebetween the rotating cutter bar and the stationarycutter. Force the stationary cutter bar snugly againstthe feeler strip. Repeat this procedure with the loweradjustment screw.

6.Tighten the socket head screws that hold the stationarycutter to the bearing housing arm.

7.Rotate the screen by hand until all of the rotatingcutters have passed through the stationary cutter.Repeat operation #3 on each of the remaining rotatingcutter bars and be sure that no vertical gap is morethan 0.002 inches.

Never sharpen the turned faces of the rotating orstationary cutter bars. Only the sides of the bars or teethshould be sharpened. To sharpen, grind only the surfaceson the front of the cutters with a fine carborundum wheel.It is recommended that a spare stationary cutter and fourrotating cutters be kept on hand at all times to permitreplacement of dull cutters without interrupting operationof the comminutor for an extended period. The rotating cutter bars have double life and can beremoved from the screen and turned end for end so theunused side faces the front. Once both edges are dullthey must be resharpened.XI.XI.XI.XI.XI. EQ EQ EQ EQ EQUIPMENT LUIPMENT LUIPMENT LUIPMENT LUIPMENT LUBRICAUBRICAUBRICAUBRICAUBRICATIONTIONTIONTIONTIONBLOWERS Check the oil level in the blower once every thirty days.To do this, open the small brass petcock on the back of theblower and remove the square pipe plug on the top of theblower gear housing. With the unit idle, pour oil slowly intothe pipe plug opening until it begins to drip from the openpetcock. Leave the petcock open untilthe oil has stopped running out. Thiswill avoid overlubrication. Too muchoil causes heating and oil leakage.Remember to close the petcock afterchecking the oil level or filling the unit.Use only SAE40 lubrication oil in theblower gear housing. Bearings at the gear end of theblower are lubricated by splash fromthe gears but the bearings at the driveend are packed with grease prior toshipment. Replace the grease with a good grade, hightemperature, ball bearing grease (drop temperature of 275ºF or better) at regular thirty day intervals. If the unit is fittedwith a grease cup, remove the grease drain plug on thebottom of the bearing housing and turn the cap graduallyuntil fresh grease appears at the drain. If the unit is fittedfor a pressure gun, do not pack the bearings too tightly.Remember to replace the drain plugs.

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MOTORS Norweco motors, used to drive the blowers, are pre-lubricated for the life of the unit. Operators should clean allthe dust away from ventilating openings on the motor everythirty days and check the motor mounting fasteners to besure they are tight. If trouble with a motor does occur theoperator should contact his Norweco distributorimmediately. The distributor will isolate the problem andprovide fast, dependable service for the unit.COMMINUTOR One lubrication fitting is located on the upper bearingcover of the comminutor. It should be filled with greaseevery six months. Use the grease gun supplied with theunit and be sure to apply a good grade, waterproof, mineralbase, ball bearing grease (Lubriplate 130-AA or equal). The motor section of the gear motor should be lubricatedonce every five years. Remove the end plate from themotor and apply the grease by hand. A good grade, hightemperature grease (GED6A2C5 or equal) should be used.The inboard motor bearing is located adjacent to the gearbox and is lubricated with oil splash from the gear section. Check the gear motor every thirty days to see if oil needsto be added. Be sure the unit is at a complete stand stillwhen adding oil to the gear motor. Remove the fillerbreatherbushing from the top of the filling elbow and the level plugat the side of the unit. Use a funnel to pour oil in the fillerelbow until it begins to run out of the level hole. There maybe a slight time lag from the time the oil is poured into thefiller hole until it becomes level with the surface of the unitso be sure to fill the unit slowly. Replace the level andbreather plugs and tighten them securely when the properoil level has been reached.PRESSURE RELIEF VALVE

Pressure relief valves are installedon the discharge piping from theblower to eliminate the possibility ofpressure build up. The valves aresimple in construction and require verylittle attention. They should be keptclean and checked periodically tomake sure rust or dirt does notinterfere with their free operation. Atleast monthly the relief valve weightand cap should be removed from thevalve body (lift straight up) and theinside of the cap and outside of the

body should be covered with a light coat of oil to insurefree operation of the valve.VALVES All air and sludge valves in the treatment plant shouldbe checked twice a year for leaks. Naturally, any leak inthe sludge return valves can be detected by visualinspection. Air valves, however, may need to be sprayedwith leak detector. Although leak detector is commerciallyavailable, a rich solution of soapy water will do the job. Anyvalve that is leaking should be disassembled and repackedwith grease or, in the case of the small air valves for thesludge return and surface skimmer, it may be necessary toinstall a new rubber washer. Be sure to note all valvesettings before repacking so they can be quickly readjustedafter the maintenance is complete.

AIR FILTERS Inlet air filter/silencers are installed at the inlet of eachblower to reduce the noise level and clean the incomingair. They must be kept clean so they will not createresistance to the free air flow into the blower. The wiremesh screen on the air filter should be coated with oil aftereach cleaning. It is recommended that plant operators keepan extra filter on hand so that it can be placed into servicewhile the dirty unit is being cleaned. To clean the wire screenin the filter, remove it from the filter body and place it in acontainer of kerosene. After it has soaked for a day or twoblow it dry with an air gun and recoat the mesh with oil.Inspect each air filter every thirty days for cleaning.XII. ELECTRICAL EQUIPMENTXII. ELECTRICAL EQUIPMENTXII. ELECTRICAL EQUIPMENTXII. ELECTRICAL EQUIPMENTXII. ELECTRICAL EQUIPMENTMAINTENMAINTENMAINTENMAINTENMAINTENANCEANCEANCEANCEANCE Generally, maintenance of the electrical apparatusshould be performed by an electrician. If any of the electricalequipment malfunctions, contact the Norweco distributorand he will have his electrician repair the equipment. Electrical leads should be checked once a year to besure they are not frayed or subject to undue vibration. Inaddition, the time clock should be checked once a week tosee that it is set to the proper time of day. At the same time,all circuit breakers, fuses and resets should be inspected.Circuit breakers should be reset as necessary and blownfuses should be replaced by the operator as required.CAUTION: Shut off all electrical power at the power sourcebefore replacing fuses or inspecting electrical wiring. REMEMBER: Repair and replacement of electricalequipment should be done by a qualified electrician. If youdo not have an electrician available your Norweco distributorwill provide the service needed!XIII.XIII.XIII.XIII.XIII. PLANT SHUT DO PLANT SHUT DO PLANT SHUT DO PLANT SHUT DO PLANT SHUT DOWNWNWNWNWN Occasionally it is necessary to shut down a wastewatertreatment system for an extended period of time. Forexample, plants serving schools located in rural areas areoften shut down for the entire summer period. Recreationalareas such as campsites may be shut down during thewinter months in colder regions of the country. Any plantthat will be shut down for longer than seventy-two hoursshould receive special care. When the shut down will befor a relatively short time, such as a week to two, it is onlynecessary to flush the inside of the blower unit with a 50-50 mixture of kerosene and oil. To do this simply removethe air filter from the top of the blower unit and pour themixture into the top of the blower while rotating it by hand.Be sure to reinstall the air filter. Do not leave the top of theblower open or exposed during the shut down period! Ifthe shut down is to be extended, several additionalprecautions should be taken. Remove the blower unit and chlorine pump and storethem in a dry place. In the case of plants installed in colderregions, it is also recommended that individual drop pipesand diffuser bar assemblies be removed so that they willnot be damaged if the contents of the tank freeze. Naturally,any shut down whether short or extended, requires flushingof the blowers with kerosene and oil. Always rotate theblower several times by hand before placing the systemback into operation. If the system has been down for anextended period it will be necessary to readjust theequipment and go through the procedures outlined in the“Start-up” section of this manual.

15

NOITIDNOC ECNARAEPPA STNEMMOC TNEMTSUJDA

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16

XIVXIVXIVXIVXIV..... VISUVISUVISUVISUVISUAL CHECKAL CHECKAL CHECKAL CHECKAL CHECK

METI YLIAD YLKEEW YLHTNOM IMES -YLLAUNNA YLRAEY

kcehclausivhguorhtoG X

neercsrabnaelC X

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sllawedistnalphsaW X

rododnarolocrofnoitareakcehC X

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17(Continued)

CAUTION: Shut off all electrical power before working on mechanical or electrical equipment.XVXVXVXVXV..... MAINTEN MAINTEN MAINTEN MAINTEN MAINTENANCE SCHEDULEANCE SCHEDULEANCE SCHEDULEANCE SCHEDULEANCE SCHEDULE

XVXVXVXVXV..... MAINTEN MAINTEN MAINTEN MAINTEN MAINTENANCE SCHEDULEANCE SCHEDULEANCE SCHEDULEANCE SCHEDULEANCE SCHEDULE (Cont.)

METI YLIAD YLKEEW YLHTNOM -IMESYLLAUNNA YLRAEY

tnemngilayellupkcehC X

retlifrianaelC X

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sgnittesevlavriakcehC X

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levelliorewolbkcehC X

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Note: Replace and lock all panels, covers and gates after performing maintenance on the plant.

18

XVI.XVI.XVI.XVI.XVI. TRTRTRTRTROUBLE SHOOOUBLE SHOOOUBLE SHOOOUBLE SHOOOUBLE SHOOTINGTINGTINGTINGTINGCAUSE CORRECTION

Motor overloadedFuses blownPower failureTimer cycled offBroken v-belt

Push reset buttonReplace fusesHave electrician checkTurn timer onReplace belt

BLOWER NOT WORKING

OveraerationLack of solidsPlant start-up

Reduce time cycleReduce time cycleNormal - continue operation

EXCESSIVE FOAMING

Clogged air lineClogged diffuserValves not properly adjusted

Clean air lineClean diffusersAdjust valves

UNEVEN AERATION

Clogged spray nozzlesClogged pump screenSpray pump not runningSpray line valve shut off

Clean nozzlesRemove pump and clean screenRepair pumpOpen valve

SPRAY SYSTEM NOT WORKING

Skimmer not workingSludge return not workingExcessive solids in hopperExcessive grease

Turn skimmer onBackwash sludge returnScrape hopperClean grease trap

FLOATING SOLIDS

Sludge return too lowSludge return cloggedPlant overloadedExcessive flow through tank

Increase sludge return rateBackwash sludge returnCheck hydraulic and organic loadingReduce sludge return rate. Shut offspray system and skimmer

SOLIDS IN EFFLUENT

SLUDGE RETURN NOT PUMPINGClogged sludge returnClogged air line to sludge returnAir valve out of adjustmentBlower not running

Backwash sludge returnClean air lineOpen sludge return air valveSee “Blower not working”

Empty solution tankPump not runningPump pluggedPump not primed

Fill tankRepair pumpClean pumpPrime pump

CHLORINATION NOT WORKING

Blower not runningClogged skimmerClogged air line to skimmerAir valve out of adjustmentInlet fitting out of adjustment

See “Blower not working”Backwash skimmerClean air lineOpen skimmer air valveAdjust inlet fitting

SURFACE SKIMMER NOT SKIMMING

Blown fusesJammed cuttersImproper cutter adjustmentWorn cuttersExcess solids in casingLow voltage

Replace fusesClean cuttersAdjust cuttersReplace cuttersClean casingHave electrician check

COMMINUTOR NOT WORKING

LIFT STATION NOT PUMPINGClogged pumpPump not workingPump overloadedPower failureControl failure

Remove and clean pumpRepair pumpPush reset buttonHave electrician checkHave electrician check

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XVII.XVII.XVII.XVII.XVII. OPTION OPTION OPTION OPTION OPTIONAL EQAL EQAL EQAL EQAL EQUIPMENTUIPMENTUIPMENTUIPMENTUIPMENTTERTIARY TREATMENT Tertiary treatment or “third stage” treatment is providedafter primary and secondary treatment of wastewater andmay be accomplished in a number of ways. Wastewaterplant effluent may enter an effluent lagoon that is sized tohold the liquid for five to seven days or even up to thirtydays. In extreme cases it may even be necessary to providea ninety day impoundment lagoon so that no effluent willbe discharged from the treatment facility during extremelydry periods. Tertiary treatment may also be accomplishedby using a sand filtration device. They are designed tofilter treatment system effluent through sand beforedischarging it to the receiving stream. Micro strainers havealso been used. They are mechanically operated devicesthat automatically strain the final effluent. Generally theymust be installed in a heated building and therefore, arelimited to use on large systems. Of the above listed devices, the most commonly usedare the smaller effluent lagoons and surface sand filters.Both are widely used and of the two, generally surface sandfilters are preferred because of the land loss involved inconstruction of an effluent lagoon. Many elements comeinto play when selecting a tertiary treatment device - thesize and condition of the receiving stream, use ofsurrounding land, location with respect to urban areas andothers. For this reason, tertiary treatment equipment mustbe selected on an individual basis for each job. Normallythe agency in control and the design engineer will worktogether to arrive at a satisfactory tertiary device.SLUDGE HOLDING TANKS Sludge holding tanks are sometimes provided withwastewater treatment plants. They are installed to storeexcess sludge until it can be disposed of or returned to thetreatment plant during low sludge periods. Normally, sludgeholding tanks are sized to provide 10% of the ratedtreatment plant capacity and are equipped with air diffusionequipment. As such, they are called aerated sludge holdingtanks and will provide odorless sludge storage anddigestion. Conventional non-aerated tanks are usually moretroublesome and not widely used. In either case, the sludge holding tanks are fed byauxiliary piping connected to the sludge return line in thetreatment plant. Plant operators must monitor thesuspended solids in the plant and when the solids levelgets too high they should divert the sludge return flow tothe holding tank to adjust the solids level down to a normallevel. All Norweco systems with sludge holding tanks aredesigned to provide extra capacity in the treatment plantblowers so that the sludge holding tank may be aerated ona continuous basis without reducing the air supplied to thetreatment facility. In addition, the holding tanks are equippedwith overflows to permit the sludge to return to the aerationchamber of the treatment plant. If drying beds have beenprovided, airlifts are also installed in the sludge holding tanksso that excess sludge may be pumped to the drying beds.Sludge need only be wasted to the holding tank when thesludge level in the treatment plant gets too high. Normallyan extended aeration treatment plant should have a mixedliquor suspended solids that ranges between 2,500 and5,000 parts per million. As long as the solids in the plantstay in this range, it should be easy to obtain reliable

treatment. However, if the solids level gets above 5,000parts per million, sludge should be diverted to the holdingtank until the suspended solids in the aeration chamberdrop to 2,500-3,000 parts per million.SLUDGE DRYING BEDS Beds for drying excess sludge are almost alwaysprovided for plants that have sludge holding chambers.Sludge drying beds are sized to provide one square foot ofdrying surface per 100 gallons of treatment plant capacity.The beds are made up of twelve to eighteen inches of filtermedia with underdrains and the sludge is taken out of theholding tank and placed in thin layers on top of the beds.The liquid drains out of the sludge and down into theunderdrains which lead back to the inlet of the treatmentfacility. The beds have precast or poured-in-place concretewalls and allow twenty-four inches of storage space abovethe surface of the sand. Usually two beds are providedand used alternately. After the sludge layer on top of thebed is dry and has built up to the point where more sludgecannot be stored, the beds are cleaned and the dried sludgeis disposed of. Sludge drying beds are not used on a regularbasis. Normally, excess sludge can be diverted from theplant to the sludge storage tank on a regular basis anddigested there without being disposed of. However, if thesolids level in the plant requires sludge wasting on a regularbasis for any period of time, it may be necessary to removesludge from the storage tank and place it on the dryingbeds. Most privately owned or operated systems have sludgedrying beds to be used by the plant operator as needed.Public systems, operated by governmental agencies, areoften not equipped with beds because enough equipmentis already available to adequately handle and dispose ofthe sludge.RISERS Precast or poured-in-placeconcrete risers are sometimesprovided for wastewater treatmentsystems, or individual elementswithin the system, to extend thesidewalls to grade. They hold backsurface water or are used to retainthe grade around treatmentsystems that are sitting too low.They may be installed as extensionsof individual sidewalls within asystem or as one large retaining wall around the entiretreatment facility. Although risers have been used widelyin the past, it is generally felt that pumping stations to liftthe wastewater are a better answer to plants that are settoo low or have high surface water. Risers, particularly thekind that are extensions of the treatment plant wall, generallymake it more difficult to maintain the equipment andtherefore, pumping stations are preferred.LIFT STATIONS Wastewater pumping stations or “lift stations” are oftenused ahead of or behind a wastewater treatment system.They are used to pump the incoming sewage up to thetreatment plant if it is sitting higher than the inlet sewer orto lift the plant effluent to a point of discharge higher thanthe treatment facility outfall. Because of the degree ofreliability needed with wastewater pumping stations, two

20

alternating pumps are installed, andeach one is individually capable ofhandling the wastewater flow.Automatic electrical alternators areused so that each time a pump runsan automatic switchover insures thatthe next time a pump comes on it willbe the stand-by pump. By alternatingthe pumps in this manner, it is possibleto obtain extended equipment life andhave a back up pump ready foroperation with the primary pumpduring high flow periods.

A number of different types of pumping stations havebeen used. Norweco manufactures a complete line ofpumping stations - six different models utilizing two entirelydifferent styles of pumps are available. A number ofaccessory devices are available with each model and theNorweco line covers virtually every wastewater pumpingapplication that might be encountered. The size, style and type of station used is normallygoverned by the pumping application, volume, location andreliability needed within the system. Naturally, eachNorweco station is sold as a complete installation includingequipment, tanks and installation with a single sourcewarranty and service policy.FLOW METERS Flow meters are provided to record the wastewatertreatment flow on a continuing basis. Norweco flow metersare simple in construction and provide the accuracy andreliability that is needed to be able to put the recorded datato valuable use. Many operating cycles in the wastewaterfacility are derived from records of the flow. Flow recordsallow the plant operator to compare performance of thesystem with the flow characteristics. Time clock settings,aeration rates and other related elements are based uponthe performance of the system and performance is usuallya direct function of system loading. Complete Norweco flowmeters and recorders are available to record and totalizethe volume of wastewater flow on a continuous basis.

CHLORINATION Chlorination stations are used to disinfect final effluentas it leaves the wastewater treatment plant. Chlorine, ahighly oxidizing agent, kills any bacteria that may be in thetreatment plant effluent. Generally, the type of chlorinedevice to be used is selected on the basis of the quantity ofchlorine required, its cost and the size of the treatmentfacility being served. Chlorine itself may be applied in agaseous, liquid or dry form. Gas chlorination equipment isgenerally more expensive than theother two types. For this reason gaschlorination systems are usually usedon larger wastewater treatmentplants. Chlorine solution, which canbe as strong as 18%, or dry chlorinetablets are easier to handle and theequipment is less expensive initially.Therefore, these two forms areusually used on smaller treatmentsystems. However, chlorine in a liquid or dry form costsmore per pound of available chlorine. Because of this, gaschlorine is almost always used on larger systems thatconsume higher quantities of chlorine and liquid or drysystems are limited to use with smaller systems that havelimited chlorine needs. Chlorine contact chambers are provided to mix the finaleffluent with the chlorine. They keep the chlorine andeffluent in contact for at least thirty minutes. Contactchambers are built as a baffled tank that is installed in thefinal outlet line. Here the chlorine is introduced at the inletend of the tank and the baffles insure complete mixing ofthe chlorine with the final effluent. The tank itself is sizedso that the flow will be retained in the contact tank for atleast thirty minutes during normal flow periods and fifteenminutes during peak flow periods. Complete gas, liquid ordry chlorination stations are available from Norweco andreplacement chlorine may be obtained from the Norwecodistributor as needed.

XVIII.XVIII.XVIII.XVIII.XVIII. TESTING & EVTESTING & EVTESTING & EVTESTING & EVTESTING & EVALALALALALUUUUUAAAAATIONTIONTIONTIONTION The effluent from the treatment facility should be inspected daily for odor and clarity. At the same time, plant operatorsshould check the condition of the contents of the aeration and settling chamber in the treatment plant. The appearance, odorand color of the aeration chamber, clarification chamber and return sludge should be noted. At least once a week, the plantoperator should conduct a relative stability, dissolved oxygen and chlorine residual check. The tests are simple and theequipment and chemicals needed for each individual test may be obtained from the Norweco distributor. Plant operatorsshould also test on a bi-weekly basis the influent and effluent BOD and the influent mixed liquor and effluent suspended solids. Individual test kits and chemicals for each of the above tests as well as complete sewage test kits are available through theNorweco distributor. The individual test kits and the overall test kit are complete and will enable the plant operator to evaluatethe performance of the system on a regular basis. Naturally, each kit is supplied with instructions for the individual tests andall of the supplies and equipment necessary to conduct the tests are included. The following chart may be used to maintain a test record for your wastewater treatment facility. It provides not only acomplete chronological record of the tests, but also a good reference that will enable the operator to make evaluations ofvarious conditions within the system on the basis of actual test results.

21

(Additional Copies Free of Charge)22

WASTEWATER TREATMENT TEST RECORD

TNEULFFE

RODO

YTIRALC

KNATNOITAREA

RODO

ROLOC

KNATGNILTTES

RODO

ROLOC

EGDULSNRUTER

RODO

ROLOC

YTILIBATSEVITALER

NEGYXODEVLOSSID

LAUDISERENIROLHC

DNAMEDNEGYXOLACIGOLOIB

TNEULFNI

TNEULFFE

SDILOSDEDNEPSUS

TNEULFNI

ROUQILDEXIM

EGDULSNRUTER

TNEULFFE

FOR WEEK OF _______________ FOR WEEK OF _______________

SUN MON TUE WED THU FRI SAT SUN MON TUE WED THU FRI SAT

IXX.IXX.IXX.IXX.IXX. MAINTEN MAINTEN MAINTEN MAINTEN MAINTENANCE RECORDSANCE RECORDSANCE RECORDSANCE RECORDSANCE RECORDSETAD TNEMTAERT-ERP NOITAREA NOITACIFIRALC NOITACIRBUL SEIROSSECCA STNEMMOC

23