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HomeMy WebLinkAboutNC0036935_Inspection and O&M Document_20201006Pine Mountain Lakes/POA NCO036935 INSPECTION PROCEDURES WASTEWATER TREATMENT PLANT AND SEWAGE COLLECTION SYSTEMS TABLE OF CONTENTS I. STATEMENT OF PURPOSE Location of Inspection Manual II. RESPONSIBILITY A. Management B. Supervisor's Responsibility C. Employee's Responsibility III. EMPLOYEE TRAINING IV. REPORTING V. PROCEDURES VI. CHECK LIST VII. TROUBLESHOOTING I. STATEMENT OF PURPOSE The purpose of this Inspection Procedure Manual is to outline basic inspection practices pertaining to the operation of wastewater treatment plants and sewage collection systems as outlined by NCDEQ-DWR requirements and 08G WWTP Operator rules ... "Inspection of facilities. Each sewage utility shall adopt procedures for inspection of its sewage treatment facilities to assure safe and adequate operation of its facilities and compliance with commission rules. Unless otherwise authorized in writing by the commission, the sewage utility shall make inspections of collecting sewers and manholes on a scheduled basis at intervals not to exceed one (1) year, unless conditions warrant more frequent inspections and shall make inspections of all mechanical equipment on a daily basis. The sewage utility shall maintain a record of findings and corrective actions required, and/or taken, by location and date. " Location of Inspection Manual The inspection manual has been prepared for use by the operating personnel of the company. Each employee shall be provided a copy of this manual. The inspection manual is continuously being updated to cover areas relating to the safe operation of wastewater treatment plants. A current copy can be obtained by contacting the company office. Any comments or suggestions on improving the inspection manual or updating information pertaining to the safe operation of equipment is welcome and can be incorporated into future editions. II. RESPONSIBILITY A. Management The employer shall have the same responsibility for inspection of treatment facilities as for any other part of the operation. The employer shall appoint only competent personnel as inspectors, who shall be responsible for those under his or her supervision. The employer shall require his supervisor to observe and enforce all regulations. The employer shall provide adequate automotive equipment, tools, and protective devices, and insist upon their proper use and maintenance. B. Supervisor Supervisors shall have the same responsibility for inspection of facilities as any other part of their wastewater operations. Supervisors are at all times responsible for inspection of facilities. Supervisors will be held accountable for quality of effluent unless investigation shows effluent quality is due to conditions beyond the supervisors' control. Supervisors shall instruct all new employees in inspection procedures at wastewater treatment plants. Supervisors shall be responsible for the training and instruction of new employees and of employees transferred to their supervision. Supervisors shall fully understand and comply with the inspection requirements of the inspection manual. They shall also ensure the inspection procedures are understood by the wastewater operators under their supervision. Supervisors shall insist on workmen observing these procedures and shall use disciplinary measures, if necessary, to obtain compliance. Supervisors shall be responsible for the regular inspection reports of personnel under their supervision. C. Employee It is the definite responsibility of each employee to maintain accurate records as to the condition of equipment and flow conditions of the plant. It is the responsibility of each employee to report to the person in charge all conditions which might affect effluent quality or machinery reliability. It is the responsibility of each employee to acquaint himself or herself with the inspection forms and procedures used in the operation of the wastewater treatment plant as soon as possible. It is the responsibility of each employee to attend all meetings possible and to take an active part in maintaining accurate records. III. EMPLOYEE TRAINING A basic knowledge of the operational procedures of a wastewater treatment plant is required to perform any type of inspection: The inspector/operator should become familiar with the following: • Basic hydraulic layout of a wastewater treatment plant; • The biological process of sewage treatment; • Mechanical operation of blowers and pumps; • Basic electrical knowledge, with emphasis on motor controls, overload protection, and timing devices. Training is normally provided on the inspection of wastewater facilities through participation in water and wastewater seminars and the state sponsored wastewater operators' schools. IV. REPORTING National Pollutant Discharge Elimination System (NPDES) reports are required on a quarterly or monthly basis as permit requires. NPDES reports and North Carolina `electronic' discharge monitoring reports (e- DMRs) are required on a quarterly or monthly basis as discharge permit requires. NPDES reporting data and NC reporting data shall be run by an NC certified laboratory, if onsite water testing facilities are not certified either field or conventional. When deficiencies are noted, it shall be the responsibility of the plant operator to make adjustments to maintain the best performance possible with existing equipment. The state Department of Environmenta shall be the primary enforcement authority, systems. V. PROCEDURES I Quality, Division of Water Resources and have jurisdiction over wastewater Each item of equipment in the wastewater treatment plant and collection system shall be inspected on a daily, weekly, monthly, or yearly basis as indicated in the attached "Wastewater Treatment Plant Operational and Preventive Maintenance Check List." Each system is free to prepare and customize their inspection forms for elements of the wastewater treatment process and collection system based on the following general outline to indicate current conditions and whether maintenance is necessary. Utilities should prepare and retain an inspection log that includes the signature of the employee and the date the inspection was performed. Management should ensure that copies of these inspection logs and forms are kept to present to NCDEQ-DWR investigators upon inspection or request. Following is a sample/suggested operation and maintenance schedule for Pine Mountain Lakes WWTP. It may not be a complete list of everything the operator should be observing, it will serve as a guide for setting up a schedule. The schedule will help the operator organize work in a step-by- step fashion and it will also help relief operators or new personnel who are not familiar with the plant. Most of the items are visual needs or maintenance needs that take little time if performed according to schedule. With regular attendance, the operator will develop ways to combine some of the duties. In many plants the size of Fontana Dam's, or smaller, that are looked after regularly by a conscientious operator, the scheduled items can be accomplished in one to two hours a day, allowing the balance of the time for lab and other duties. WASTEWATER TREATMENT PLANT OPERATIONAL AND PREVENTIVE MAINTENANCE CHECK LIST GENERAL OUTLINE FOR INSPECTION PROCEDURES Frequency As Operational and Preventive Maintenance Daily Weekly Monthly 3 Mo 6 Mo Yearly Necessary 1 SEWAGE TREATMENT FACILITIES SURVEY FOR THE FOLLOWING CONDITIONS: Plant Area X a. Check fence damage X b. Check plant area Building & Grounds X a. Check security measures are in place 'and current X b. Insure adequate house/grounds keeping 2 PRELIMINARY/PRETREATMENT a. Clean inlet, screens, and properly dispose of trash X X b. Check inlet flowmeter and floatwell c. Remove and dispose of rags and accumulation from comminutor and X bar screen X d. Check for rock or metal objects in comminutor channel e. Observe flow and cutting action of comminutor f. Remove scum from grit chamber, X and was down grit chamber 3 PUMP STATIONS X a. Remove debris X b. Check pump operation X c. Clean floats, bubblers, or other control devices X d. Lubricate pump e. Check exhaust fan X X f. Check dehumidifier X g. Check alarms X h. Check sump pumps Frequenc As Operational and Preventive Maintenance Daily Weekly Monthl 3 Mo 6 Mo Yearly Necessary 4 COMMINUTING DEVICES a. Check comminutor blades X b. Sharpen comminutor blades when cutting edge is worn 1/8 inch X X c. Check oil level d. Grease if called for in manufacturers instructions X 5 CHLORINATORS/DECHLORINATORS a. Check solution level in self-contained solution crock X b. Check chlorine/S02 cylinders X c. Check feed rate X d. Change chlorine/ S02 cylinders X e. Check Hypochlorinator/Dechlorinator Unit X 6 FLOW MEASURING DEVICES X a. Check and clean floats, etc. X b. Verify accuracy 7 VALVES AND GATES X a. Check to see if set correctly X b. Check electrical controls X c. Check control housing X d. Check for unprotected electrical connections 8 CENTRAL CONTROL SYSTEM a. Check timers X b. Check electrical controls X c. Check control housing X d. Check for unprotected electrical connections X 9 AERATION BASIN a. Visually check aeration system for even air distribution; no dead spots X X b. Raise and clean rags from diffusers c. Check oil level in mechanical aerator gear cases X X d. Check oil level in blower gear cases e. Check for air leaks around base and fittings of blower X X f. Check blower belts for wear and tension g. Check blower motor and bearings for excessive heat X h. Check aeration system for unusual noises or vibration X Frequency As Operational and Preventive Maintenance Daily Weekly Monthly 3 Mo 6 Mo Yearly Necessary i. Log running time for mechanical X aeration j. Check amperage on mechanical aeration X 10 CLARIFIER a. Scrape sides and sloping bottom of clarifier X b. Check to see if sludge collection arm is turning X X c. Remove any floating material on top of clarifier d. Check sludge recirculation system X X e. Check scum recirculation system 11 CHLORINE CONTACT TANK X a. Remove any floating material on top of contact tank b. Remove sludge from chlorine tank when needed X c. Visual check of baffles for proper placement to ensure proper chlorine X contact time 12 TERTIARY TREATMENT X a. Clean screen on mico-strainer b. Lubricate mico-strainer X X c. Check backwash pumps d. Check backwash surge chamber pumps X X e. Check media 13 PUMPS AND MOTORS a. Check for blockages in RAS return pump X X b. Check pumps for clogging or near clogging condition X c. Clean screen at intake of suction piping of pump X d. Lubricate pump bearing X e. Check pump bearings temperature f. Drain pump lubricants, wash oil wells and bearings with kerosene X X g. Check pump bearings for wear X h. Check alignment of pump and motor flange with straight edge X i. Check motors for heating j. Replace pump packing X X k. Check pump shaft sleeves Frequency As Operational and Preventive Maintenance Daily Weekly Monthly 3 Mo 6 Mo Yearly Necessary I. Replace pump shaft sleeves X m. Examine pump wearing rings (manufacturer should specify what is X excessive) X n. Clean water seal piping X o. Inspect foot valves and check valves 14 OPERATIONAL CONTROLS X a. Observe odor, color, and foam of aeration tank b. Perform necessary operational and control tests (settle ability test, pH, X chlorine residual, etc.) X c. Perform tests as required by NPDES permit and regulatory agency 15 COLLECTING SYSTEM a. Sewer lines X X b. Manholes 16 SLUDGE WASTING/STORAGE SYSTEM a. WAS lines, pumps X b. Storage Tank System & sludge level X The utility will also make an inspection on the receipt of a report of a potentially hazardous condition made by a qualified employee, public official, or a customer. Appropriate records will be kept to identify the inspection made, deficiencies found, and action taken to correct such deficiencies. TROUBLESHOOTING Troubleshooting begins by knowing the system. The operator needs to know: 1. What each part of the system is supposed to do. 2. How each process or piece of equipment operates normally. 3. How to recognize abnormal conditions. 4. What alternatives are available when trouble develops. Briefly, to recognize when something is bad, the operator must know how it works when no trouble exists. The purpose of this section is to present a ready and quick operator's reference to process problems and their solutions. The table is arranged in columns as explained below" Condition: The information in this column shows what has been indicated or observed by the operator. Possible Cause: This shows the most likely cause of the indicated upset. Solutions: The operator should arrange the suggested solution in the order that he/she wants to try them and proceed from the easiest to the most difficult. Reference: The number appearing in this column show where the operator can find additional information. Condition Possible Cause Solution Reference Controls 1 Pump fails to start 1. Overload relays tripped; 1. Inspect see 2. Overloads trip starter coil damaged; "Motors"; call 3. Starters chatter HOA switch off; electrician alternator damaged 2. See "Motors" 2. High amperage draw 3. Clean, inspect or 3. Starter contacts replace burned; dirty contacts in contactors alternator Pumps 1 Unusual noise 1.Plugged impeller or 1. Clean 2. Overloads trip suction; reciprocating intake/screen pump pumping water remove pump instead of sludge housing and (knocking noise.) unclog impeller, 2. Plugged pump turn off pump priming line; see 1 and check above clarifier sludge 3. Broken impeller, blanket. worn wear rings; 2. Remove and see 1 above unplug line; check impeller for debris. 3. Disassemble, replace impeller; measure wear rings OBSERVATIONS PRETREATMENT 1Naiking around the plant following the normal flow route gives the operator an idea of the type of wastewater the plant has received since the last visit. Following are some of the indicators_ Odor Odors in the area niay indicate evidence of septic sew- age, scum buildup, or a strong industrial waste in tha waste - Haw are odors controlled? water. If so, a temporary solution is to wash down the entire area to remove the scum. If grease or industrial waste becornes a problem, the operator should locate the source and attempt to control it at its source through the use of existing ordinances or discussions with the contributor. Other sources of'the odor may be an accumulation of rags and other debris an the comminutor or bar- screen. Fre- quent removal (twice daily) and daily disposal by burying it I help to control the odor, Color The color of the influent tells a lot about the waste. A black color accompanied by a septic odor may indicate that What does a buck influent part of the wastewater is staying in level sewer lines during color and septic odor tell? low flow periods. The low flow results in solids settling out and slowing down the flow. Manholes should be inspected for the buildup of sludge and/or sand. These lines and man- holes require periodic flushing. A source of information on how to locate and flush the lines is: Handbook for Sewer System Evaluation and Rehabilitation Publication No. EP-A 430/9-75-021, December, 1975, MOD-19 Silt in fines? A reddish or brown color may indicate silt getting into the lines whiC, in turn, increases the wear on and requires mare frequent maintenance of pumps and other mechanical items, Source of the slit may be a broken line or a side sewer excavation. Visual A high-water mark greater than normal in the inlet channel may indicate a high flow during operator's absence What does a "high-water or plugging downstream in the bar.screen or comminutor. mark " indicate? These areas should be checked for proper operation. Con,- minutor blades may be dull and may riot be providing good cutting action. AERATION TANK The operator should observe the entire aeration tank surface for turbulence. Though some of his conclusions Turbulence wil I be based on past experience, the extent of surface activity will show if the contents are thoroughly mixed Now to tell if complete throughout the entire aeration tank. Watching the surface mixing is occurring. fur dead spots wi 11 tell if mixing is the same throughout the aeration tanks. An equipment modification for eliminating dead spots in the aeration tank is shown in the Case Histories section. The operator should raise or lower air usage based on Dissolved Oxygen (DO) readings. See Section 4—Operational Procedures for information on proper DO levels in the aera- tion basin. What may cause law DO? It the DO does not increase above 1.0 when all aeration equipment is operating, it may be due to plugged air lines, blower not sized right, or high strength waste. If normal air feed fails to raise DO over a 24-1 our period, a further check of the mechanical air system may be needed. Surface Foam and Scum The type of foam or scum, if any, on the aeration tank surface, and to a lesser extent, the color of the mixed liquor gives the operator a clue to how wel I the process is working. What type of foam should Fresh, Crisp, Wbite Foam: Only a modest accurnula- be present? tian of white, or at least light colored, crisp appearing foam is usually present on aeration tank surfaces when an exoelient final effluent is produced. The operator should take note of the conditions in the process and keep them within these ranges because whatever is happening is just right, Excessive, Billowing White Foam: If the aeration tanks are covered by thick billows of white sudsy foam, the opera- tor can be quite certain that the sludge is too young and that sludge age should be increased by reducing the sludge wasting rate. Operators who have -actually gone through this white foam cycle realize that not all foam is caused by detergents. What causes thick dark Thick, Scum -my, Dark Tank Foam: At the other foarn? extreme, the operator may observe a dense and somewhat greasy scummy layer of deep tan to brown foam covering the entire aeration tank surface. Such foam almost always indi- cates that the sludge is too old and possibly overoxidized. In this case, the answer is to increase sludge wasting rates. Here again, the sludge wasting rate should usual iy be increased gradually, possibly 24 percent of return rate per day, on a day -today basis while watching the graph plot to see how the changes affect the effluent and mixed liquor Sol ids. • What do hydrogen sulfide Sludge Color and Odor: At times a poor quality, ex - odors mean? tremely dark brown colored sludge, releasing hydrogen sulfide odors maybe seen in the aeration tanks. It does not take much experience to recognize this problem. The solution is to increase air discharge rates immediately to pro- vide a 2-3 rng/L DQ in the aerator. A time clock may be nec- essary tD keep the DO up. See Part I, Section 4, Aeration Basin, for a typical time clock setting. When the system is operating well, it will generally have a dark brown aeration tank color and will be accompanied by an earthy odor. If the mixed liquor solids level becomes too low, the odor will either disappear or change to that of fresh grease or lard. CLARIFi ER The operator should also observe the final effluent and the clarifier water surface to sae how the process is working. Final Effluent Appearance if the final effluent appears clear or its improving day by day, obviously the operator should continue to do what he If the effluent is clean —fine! has been doing. 1:}M11111 If not, something needs to However, H it appears turbid or contains noticeable be dome. solids, trouble may be just around the corner. Visual observations and control tests will help to show what needs to be done. Final Clarifier Surface Sludge hulking: Operators who have experienced true Appearance classic sludge bulking find it all too easy to remember and identify. It will usually show up as a uniform sludge blanket that lies a few inches below the surface of the entire clarifier. and may even cause the mixed liquor solids to pour out over the final effluent weirs. It may be due to shock loadings and inefficient aeration devices; however, classic sludge building usually is caused by improper operational control rather than by inadequate plant capacity - How is sludge bulking This type of bulking, which is practically always assoc 1- co.ntrolled? ated with y.Oung sludge, usually can be eliminated by reduc- ing sludge wasting rates and changing return sludge rates_ If a centrifuge is used to find RAS concentrations, the goal should be to adjust the return rate to equal the concentration found in the settlometer settling test after 2-3 hours of settl- ing. This concentration can be found by multiplying the mixed liquor concentration by 1,000 and dividing by the volume settled after 2-3 hours. Adjust the return rate either up by 20 percent to cause the desired change and recheck after 24 hours. 14 this causes improvement, keep going in this direction. If not, move return in other direction. Sludge blanket in the clarifier should be watched for improvement too. Some sludge may still be lost in the effluent, but the goal is to bring the sludge quality back into a good range. If the plant has the capability, contact stabilization might also be tried if the condition does not improve in 10-14 days_ For further information, see EPA Bulletins 330l9-74-001 a, b, c, d, and e and Operator Pocket Guide to Activated Sludge, Part 11, listed in the References Section Of this manual. How does solids washout Sludge Solids Washout: Excessive sludge washout differ from sludge bylking? over the final effluent weirs, when the upper surface of the siludge blanket is more than three feet below the clarifier water surface and when sludge settles properly in the lab- oratory tests, should not be confused with classic Sludge bu I k i ng. Solids washout is generalay caused by hydraul is over- loading, improper clarifier inlet port arrangernents, or faulty final effluent weir locations or a combination of these. Clumping: At times, large masses of sludge, possibly four inches (0.1 1 meter) in diameter, may be seen rising, then bursting, and finally spreading over the clarifier surface. This has sometimes been called "clurnpIng," This may also indi- cate a need to scrape the sides of sloping clarifiers that do not have mechanical sludge removal_ Ashing: At other times, smaller sludge particles usually sleep brown to gray in color, may rise and then spread over the tank surface. Some operators call this "ashing." What happens when the Th is problem occurs when sludge age is too aid and it sludge age is too old? can usually be el iminated by increasing sludge wasting rates. Reducing air discharge rates to the rninimum levels that will stiI I maintain aerobic conditions in the aeration tanks may also be helpful. >Vhat factors make Straggler Floc: At times, small, almiost transparent straggler floc worse? very light fluffy, buoyant sludge particles (1/8 to 1/4 inch, 3-6 mm in diameter) may rise to the clarifier surface near the outlet weirs. This condition is usually worse in a shadow clarifier and may be especially noticeable at high return sludge flow rates. When this type of straggler floc is observed while the final effluent is otherwise exceptionally clear, and if it is present even during relatively low discharge periods, sludge age should be increased. Since this type of straggler floc usually occurs at relatively low mixed liquor solids concentrations and is usually worse during the early morning hours, it may be reduced by cutting back an sludge wasting rates 1 G-20 percent, This wi II increase sludge age. Return sludge and air discharge rates are controlled by re- sults calculated from other control tests. What is pin floc? Pin Floc: Very small compact pier floc, usually less than 1/32 of an inch (0,8 mm) in diameter, may be observed sus- pended throughout moderately turbid final clarifier tank con- tents, This is a strong indication that sludge age is too high and the sludge has become overcxidized. This results from high return rates which Ouse the sludge to make too many passes through the aeration in a days time. How does settlometer The settlometer test will confirm this if rapidly -settling, test confirm grin .floc? discrete sludge particles appear as individual "grains" or gran- ular rather than clumping together. The sludge tends to accumulate rather than compact while forming a settlumeter sludge blanket. In essence, granular sludge particles are fall- ing through a turbid liquor rather than compacting and squeezing out a clear.final effluent. When final clarifier characteristics are confirmed by the settlometer test, the sludge wasting rate should be increased while return sludge flaw is adjusted to meet other control test demands. RETURN ACTIVATED The Return Activated Sludge (RAS) condition should St- UDG E be observed as Gt discharges into the aeration basin. A good RAS has a brown color, no offensive odor and good settling in the clarifier prior to pumping to the aeration tank. What are the causes of A black and odorous sludge indicates that it has turned a septic RAS? septic. Two passibIa causes are an excessively Iow rate of sludge return and not enough air supplied to the aeration basin. The first results in the sludge remaining in the clarifier too long and since -it doesn't receive aeration, the sludge turns septic.. The aeration basin should be checked for dissolvers oxygen to see if low DO (less than 0.5) is the cause. Is the pump operating Sludge should be returning from the clarifier all the time correctly? unless it is necessary to shut it off to waste and then only for short periods of lime (1-2 hours maximum). Material that Wows into the clarifier may plug the suction lire. This re- quires nodding out or blowing back with air or water. Air lift pumps may not operate because the air line con- trol valve vibrates shut. Valves should be checked each time the operator passes them. Handles and sterns should be ad- justed so they are tight and not knocked out of adjustment by humping or vibration. Is-retuen sludge measured? The meter or measuring dev toe for return sedge should be read and a record kept on rate of return as well as total pumped each day. Float type meters need to be checked daily to be sure nothing interferes with free operation of the float. Grease and sticks sometimes cause the float to stay In one place regardless of the flow, causing false readings. Weirs that measure flaw must be kept clean. Grease, weeds, trash, or thick sludge that collects on the weir edges will cause falsely high readings. The weirs should be checked and cleaned daily. WASTE SLUDGE Many small plants were never provided with a way to waste sludge nor a place to waste it to. Several suggestions are made in later portions of this manual to solve this problem. Watch the wasting Other plants have methods of wasting either on a batch operation closely. basis or continuously to an aerobic digester or to a holding tank. It Is generally the best practice to waste only while the operator is on site to watch the operation. It is important to calculate the amount needed to be wasted and than to be sure not more than that amount is drawn out. When waste valves are left open overnight it is too easy to either waste M too much or something plugs the line up and nothing is wasted. Valves, meters; and pumps used in the wasting proce- dure should be checked at least every other hour when in use. TOTAL SLUDGE LOSS Sometime, the operator may corne to the plant and find that all or most of the solids have been washed out or wasted cops! from the punt. The two most probable causes are hydraulic washout due to high flows or accidentally leaving a valve open. Getting back in operafion_ Jn either case, it will be necessary to start over end build new anvated sludge. Several options are available: Beg 1. Check with a neighboring activated sludge plant and see if some return sludge can be hauled in and dumped in the aeration basin. By using 5,000 gallons of return sludge at a concentration of 10,000 mg{L in an aeration tank holding 50,000 gallons an instant MLSS of 7,000 rng/L would resat. Borrow 2. If the plant has an aerobic digester or holding tank, some of these solids could be transferred to the aera- tion tank, The tugs will not be as healthy but it will cause the process to come back faster than start- ing from "scratch." Start from "scratch" 3. If it is necessary to start from nothing, it can be done by setting the return rate at maximum for 2-3 days and stopping wasting until the proper level of solids are built up. There will probably be foaming in the aeration tank and chemicals may be needed to keep it down. Also, a lawn sprinkler can be set up to spray aver the surface of the tank, It may take 8-12 days to get hack to normal. Return rates should be cut back at about 10 percent per day after the first 3 days. No wasting should be done until Back to normal. One other problem might result in sludge loss and this may he due to "taxis'" or poison materials coming to the plant. Metal wastes, high organic content, or law or high pH are same of the possible causes. The sludge may lose its ability to settle and go out over the weirs. The source must be found immediately and stopped. This requires the help of regulatory people usually. Plant startup may be done in any of the above ways after the problem is found and corrected.