William G. Maddox Environmental Specialist II, Valley Regional Office Department of Environmental Quality 4411 Early Road, Harrisonburg, Virginia Office: 540-574-7831, FAX: 540-574-7878 [email protected] Web: www.deq.virginia.gov Mail: P.O. Box 3000, Harrisonburg, Virginia 22801 List of Field Parameters Dissolved Oxygen pH Total and Free Residual Chlorine Temperature (Turbidity – not a common effluent limitation.) Note: Flow rate is a measurement, though not obtained using a water sample analysis. It is an effluent discharge characteristic or parameter. Regulation DEQ Mission Statement: DEQ protects and enhances Virginia's environment, and promotes the health and wellbeing of the citizens of the Commonwealth. Over 5,000 people die worldwide everyday from drinking or bathing in water containing the same contaminants that are removed at wastewater treatment plants. Regulation Clean water regulations accounted for benefits of up to $8 billion at a cost of $2.4 to $2.9 billion. Clean air regulations provided up to $163 billion in benefits, while costing taxpayers only about $21 billion. http://usgovinfo.about.com/library/weekly/aacost-benefit.htm Regulation Bureaucratic red tape, the difficulty of finding information, lengthy training in regulatory requirements, having to constantly revisit changing regulatory policy, and haphazard enforcement of the rules may be an immediate concern but… http://www.berr.gov.uk/files/file53236.pdf Regulation You have a stronger, fuller, more aware understanding of regulation than average and can see that… Your efforts support living in a clean and healthy Virginia environment, benefitting your family and avoiding health risks for you and others around you. You can help others understand this. Regulation Testing is intended to be “reliable, uniform, and accurate.” (SM, Preface) We are considering “field testing and measurement” of water at the site where the sample was taken or nearby, not testing and measurement performed in an environmental laboratory. Analysis is immediately or within 15 minutes holding time maximum. “Field testing” term originated in testing military equipment under field conditions. Field Testing Characteristics of the parameter dictate the equipment design and sampling (grab or in situ). The ideal design could obtain the same result from any such instrument of a test of a sample anywhere, every time. No ideal instrument exists. We do our best (hence method regulation, choices, and lots of care, and the dynamics of improvements). Field Test – Be Aware of Individual Variables Example - a simple contact sensor like a thermistor for temperature (or liquid in glass or thermocouples and such): Measures its own temperature, so must be in equilibrium with the media it is contacting (water – no heat flow between them) Electrical properties are important (resistance, current – THERMal resISTOR) Water is dynamic with lots of possible variations in temperature (surface, depth, aeration, movement) Field Testing – Four Basics Measure or sample for a representative result of the discharge characteristics Follow approved method Follow instrument manufacturer’s recommendations Keep good records Field Testing – You Know…. VPDES Permit Part II A 2: Monitoring shall be conducted according to procedures approved under Title 40 Code of Federal Regulations Part 136 or alternative methods approved by the U.S. Environmental Protection Agency, unless other procedures have been specified in this permit. 40 CFR Part 136… EPA Federal Register - Guidelines Establishing Test Procedures for the Analysis of Pollutants Under the Clean Water Act; Analysis and Sampling Procedures Field Testing Need initial demonstration of capability (IDC) available for each analyst/operator performing analysis. SM 1020 B.1 For once per month analysis frequency or less, establish a set time each monitoring period for sampling and analysis. If that will not provide a sample representative of the monitoring period, collect more samples/perform more analyses. Dissolved Oxygen Winkler (Azide modification) SM 4500–O B–2001, C–2001, D–2001, E–2001, F–2001. ASTM D888–09 (A) USGS/AOAC/Other 973.45B3, I–1575–78.8 Electrode SM 4500–O G–2001 ASTM D888–09 (B) USGS/AOAC/Other I–1576–78.8 Luminescence Based Sensor ASTM D888–09 (C) USGS/AOAC/Other Footnote 63 Hach Method 10360, Luminescence Measurement of Dissolved Oxygen in Water and Wastewater and for Use in the Determination of BOD5 and cBOD5. Revision 1.2, October 2011. Hach Company. This method may be used to measure dissolved oxygen when performing the methods approved in Table IB for measurement of biochemical oxygen demand (BOD) and carbonaceous biochemical oxygen demand (CBOD). Footnote 64 In-Situ Method 1002–8–2009, Dissolved Oxygen (DO) Measurement by Optical Probe. 2009. In-Situ Incorporated. Dissolved Oxygen Oxygen, Dissolved Probe Container - G, Bottle and top Preservation - None required Maximum holding time - Analyze within 15 minutes. Winkler Container - G, Bottle and top Preservation - Fix on site and store in dark. Maximum holding time - 8 hours. Use APHA-type sampler (American Public Health Association specifications - Displaces three times bottle volume without aeration) …or analyze in-situ (Latin – literally “in place”) Dissolved Oxygen Guides: Verify the accuracy of the temperature monitoring device on the meter at least annually over the operating range of the meter. Show calculations of correction factors applied for each recorded temperature measurement. Be careful not to represent the temperature recorded as effluent temperature if the sample was not collected in accordance with effluent temperature monitoring procedures. Dissolved Oxygen Guides: Reactive compounds and gases (like hydrogen sulfide and other sulfur compounds) can interfere with the reading by reducing probe sensitivity for membrane probes (optical probes not affected by gases like hydrogen sulfide). Measure D.O. after all treatment, including post aeration. Keep sensor in moist environment. For the optical D.O. method, do not use organic solvents to clean the sensor but just wipe off any fouling gently with lens cleaning tissue. Dissolved Oxygen Guides: The instrument, both electrochemical and optical, senses the partial pressure of oxygen at the surface of the membrane, rather than the actual concentration of oxygen (weight/volume). The relationship between partial pressure and concentration is dependent upon atmospheric pressure and temperature when a reading is made in the air (i.e., during the air calibration procedure), whereas, the equilibrium solubility of oxygen in water is influenced by temperature, salinity, and pressure (of the gaseous phase). Dissolved oxygen Guides: For digital instruments (YSI), the software compensates for the temperature-related factors after instrument calibration and during readings (temperature measured by a thermistor). Importance of D.O. Low dissolved oxygen can impact a stream or lake from microscopic consumption of organics in wastewater treatment plant discharges by reducing oxygen sensitive animal populations. Warm water discharges can lower the oxygen content in streams and lakes as well because warm water holds less dissolved oxygen than can cooler waters. Low dissolved oxygen in streams and lakes can result in anaerobic activity byproducts that are objectionable, odorous. Oxygen levels high and low are important for treatment processes. pH Electrometric measurement. SM 4500–H+ B–2000 ASTM D1293–99 (A or B) USGS/AOAC/Other 973.41,3 I–1586–85.2 Automated electrode EPA 150.2 (Dec. 1982)1 USGS/AOAC/Other - See footnote,21 I–2587–85.2 pH Container – P (polyethylene), FP (fluoropolymer – PTFE, Teflon), G Preservation - None required Maximum holding time - Analyze within 15 minutes. pH Guides: Verify the accuracy of the temperature monitoring device on the meter at least annually over the operating range of the meter. Show calculations of correction factors applied for each recorded temperature measurement. Be careful not to represent the temperature recorded as effluent temperature if the sample was not collected in accordance with effluent temperature monitoring procedures. pH Guides: The change in the dissociation constant of water with temperature means that a temperature recording will need to go with each pH measurement. A true pH neutral point at 7 with no acid or base, pure water, only applies at 25 C. For the same pure water, at 0 C the measured pH would be 7.47 and at 60 C would be 6.51. Most pH measurement issues are due to fouled or poisoned electrolytes and a clogged reference junction. So, manufactures of pH electrodes spend a lot of effort to create and design electrodes that deal with those issues. pH Guides: Know that pH is measuring the hydrogen ion concentration altered by a combination of known and unknown effects of the meter and electrode. Calibration is the means to allow for these. The outer surface condition of the glass bulb is critical. The voltage measurement is between the two surfaces of the glass (sample solution side and conductor of electrode side). pH Guides: The electrode glass surface must come into equilibrium with the solution being measured. Each glass membrane has an imperfection in its potential-generating nature (asymmetry potential). Calibration takes care of all if electrode is cared for. One error of electrodes can be caused by light below 470 nm(is why they often have light-shielding – dark color and such). Silver metal exhibits photoelectric effect. pH Guides: Reference electrode portion has a junction or double junction that can clog, particularly in protein solutions (double junctions help prevent this). Small currents can be induced from fluorescent lighting and AC motors and such. Do not let glass electrodes go dry. Several layers of water molecules form a hydration layer on the glass membrane before potentials stabilize. pH Guides: Sealed electrodes should not be stored in DI water— Reason: the sample will accelerate the leaching of reference solution, which cannot be replaced. Alkaline buffers will dissolved the glass and shorten electrode life (store according to manufacturer). Static charges can be transferred to glass electrodes. The pH buffers contain high concentrations of phosphate. Care must be taken during calibration to avoid leaving traces of buffer on equipment or at the workplace that could contaminate water samples. Importance of pH pH affects solubility and biological availability of chemicals in water, including nutrients. pH affects life processes that require conditions within a certain range of pH. Certain compounds are more toxic at lower pHs (metals more soluble). Total Residual Chlorine (TRC) Field TRC measurements have a number of EPA- approved methods. Most common are DPD and amperometric methods discussed here. TRC Amperometric direct SM 4500–Cl D–2000 ASTM D1253 DPD–FAS SM 4500–Cl F–2000. Spectrophotometric, DPD SM 4500–Cl G–2000. TRC Container - P, G Preservation - None required Maximum holding time - Analyze within 15 minutes. TRC Guides: DPD method most widely used. Protect DPD powder reagents from temperature extremes (keep between 50 – 70 F). Avoid excess agitation and exposure to sunlight when sampling. Rinse sampler container with several volumes of sample before collection to help eliminate any possible chlorine demand on the sample container. Source Chlorine Analysis Technical Information Series, Daniel L. Harp, – Booklet No. 17, HACH TRC Guides: Testing can have oxidizing agent interferences – chlorite, chlorate, bromine, oxidized manganese and such (most methods subject to interferences from turbidity, color, inorganic and organic compounds and sample buffer capacity. Photometer zeroing compensates for some color and turbidity. Check DPD reagent buffering capacity annually. Temperature Thermometric SM 2550 B–2000 USGS/AOAC/Other - See footnote.32 (Footnote 32 ‘‘Water Temperature–Influential Factors, Field Measurement and Data Presentation,’’ Techniques of Water-Resources Investigations of the U.S. Geological Survey, Book 1, Chapter D1. 1975. USGS.) Temperature Container - P, FP, G Preservation - None required Maximum holding time - Analyze. Temperature Guides: Many technologies exist to measure temperature. DEQ normally will see the liquid in glass thermometer, the thermistor, and the dial-type thermometers (bimetallic). DEQ supports not using mercury thermometers for field testing. Annual verifications or units purchased and being used within the expiration dates are needed. Verification is against an NISTtraceable thermometer over the operating range of the unit (multiple check temperatures), with records on site indicating the information with the reference thermometer certification and that that certification is up to date as well. Temperature Guides: Do not report held samples’ temperature as “effluent” temperature (common error). Analyze effluent temperature immediately and/or in situ. Common means of measurement is by an instrument that measures the temperature of itself, so no heat exchange should be occurring between the unit and the sample (needs to be stable). Record Keeping – From the Permit Records Records of monitoring information shall include: The date, exact place, and time of sampling or measurements The individual(s) who performed the sampling or measurements The date(s) and time(s) analyses were performed The individual(s) who performed the analyses The analytical techniques or methods used; and The results of such analyses. Record Keeping Guides: The test method references on site should be up to date for all records (often see up-to-date references mixed with older ones – very commonly seen). E-documents are to be as accessible on site as would be hard-copy paper documents. Record Keeping Guides: Use no faulty field test equipment for permit-required monitoring records (temptation is to use it if can and then get it fixed later). Critical equipment should have spares available. If pH electrode reading too slow – do not use it to record a pH. If DPD reagent expired, do not use it (same with buffers). May be good past dates, but cannot know. For recording errors – line through once and initial. Use indelible ink for writing. Record Keeping Guides: Exact sample location is to be exact (correct in all details) - often see inexact location records. Keep separate sample times and analysis times (common problem) unless in situ. Thermistor verification check tags are often missing from meters and should not be (verification by name, the date, and any correction factors for tags). Record Keeping Guides: Detailed field equipment maintenance records are important for a number of reasons – help preserve assets - in an enforcement action they may become critical. The wastewater field involves discharging toward neighboring properties. YOU ARE NOT ALONE. Record Keeping Guide (IMPORTANT): Keep accurate records. Plant conditions can change rapidly. Do not try to write a book in a 1 mm X 1 mm form space, or a book all on one page. Record Keeping Guides: When a letter of explanation is required for an exceedance, and the cause of a problem is not known, often the permittee states the result must have been a sampling or analysis error. Another cause or two might be – using this reasoning – an unknown substance discharged, temporarily affecting the result, or an unknown interferent with the test may have discharged temporarily. Record Keeping Guides Keep an up-to-date O & M Manual on site for field testing information. What records the manual states are suggested to be kept and what actually are kept can be world’s apart. Test methods often out of date, and equipment used out of date. Record Keeping Guide: If a problem occurs and a helpful record keeping was found insufficient for any reason, start keeping it. Case-specific record keeping can be GREAT for you (e.g., spare meter operations check).