Ask the Experts Discussion Page

Following are questions posed on the Ask Our Experts Page and the corresponding answers.

Question Submitted by Anonymous, Received 03/28/02:

I have accidentally contaminated my well by allowing a hose to remain in a barrel after the hydrant was shut off. The barrel contained a saddle blanket with some mineral oil spilled on it. Now when water is drawn from the tap, it develops an oily been after sitting for a few minutes. There is no taste or other symptoms. My horses and other live stock drink the water with no hesitation. Is there safe surfactant that can be introduced into the well to counteract the surface "shine"?

Response to Anonymous, Posted 04/01/02:

Provided by TNRCC staff member: I do not (personally) know of any NSF-certified surfactant although I'm sure that some exist. Assuming that the well is a domestic/agricultural well, I'm not sure I would worry much about the sheen unless the barrel or blanket had something in it besides a little mineral oil. You may want to talk to a driller or licensed pump installer to find out what they use when cleaning up a well that has a bacterial problem. Several of the bacterial species that colonize wells have a polysaccharide slime layer and are resistant to disinfection unless a surfactant (or wetting agent) is used to help penetrate the layer. I realize that the two "contaminants" do not have the same chemical structure but the driller/pump installer may be able to help solve this problem since both the oil and slime layer are organic.

Question from R. J., Received 11/28/01:

I operate a small .1 MGD plant. We average about .04 MGD. I have a poultry company that wants to build an equipment washing station. They say they will use about 25-30k gal/month. They will use tri-phenol-r/256 as a disinfectant. Solids are to be trapped before water enter sewer system. Should this be a concern? Where would I go to find what precautions to take if any. Thanks.

Response to R.J., Posted 12/20/01:

Given the information about the chemical used as a disinfectant, I cannot tell by the brand name if this is a compound that the State of Texas regulates. If this compound is toxic in nature, according to the Material Safety Data Sheet, then the receiving plant does need to take certain precautions (please also check for any potential explosive and/or corrosive effects). If the rate at which the wastewater is being discharged to the plant is a slow bleed, versus a batch discharge, this can change the potential effects on the receiving plant. Another factor is how close to the receiving plant this facility is located. If the facility is immediately upstream of the headwork's of the plant, this may have a significantly different effect than if the facility were located far up into the "sewer shed" with potentially significant dilution before reaching the headwork's of the plant. The time of day is also an important factor. If the discharge occurs during normal working hours between 8 am and 5 pm, there may be potentially less effect on the receiving plant than if the discharge were to occur in the middle of the night. If the plant receives the discharge and the operators notice any inhibition of the microorganisms (it was not specified in the question whether this was an activated sludge type of plant), the plant may decide to halt or restrict further discharges until some bench scale studies to determine the amount of this compound the plant is able to receive without inhibition occurring. It might be a good idea to monitor the influent and effluent of the plant for the particular compound to see if any removal occurs. If the compound is measured above the minimum analytical level in the effluent, or any inhibition occurs within the plant, some biomonitoring tests of the plant effluent may be justified. If this plant is a publicly owned treatment works and there is an ordinance providing legal authority over the service area, the ordinance should be reviewed to see if there are restrictions pertaining to the discharge of this pollutant into the collection system. Please let me know if I can be of further assistance. Jill Russell, Pretreatment Team Leader TNRCC Water Quality Division, You may contact me by telephone at (512) 239-4564 or you may e-mail me at jrussell@tnrcc.state.tx.us

Question from Anonymous, Received 11/25/01:

It was brought to my attention today that water meter readers, of as June, 2001, are not allowed to change meters unless a certified water distribution employee is over seeing the project. My meter readers are not certified in water distribution and I need to know if this information is correct. The gentleman that gave me this information said he was told that since meter readers are not classified as being in water distribution that there are no classes for them to take for certifications. Can you help me with info regarding this matter? Thanks for your help.

Response to Anonymous, Posted 11/30/01:

The procedure to correctly change out a meter requires a disinfection process, therefore, a Class D Water Operator or above is required to handle or directly supervise the procedure. Obtaining a Class D Water Operator License does not require any experience. Applicants only need to complete the Unit I Basic Waterworks course, submit an application and the appropriate processing fee to the TNRCC, and pass the examination. To qualify for a Class C Water distribution License, applicants must have 2 years of water distribution experience (one year may be substituted with college or additional water operator training). Changing meters qualifies as distribution experience, but reading meters does not qualify as distribution experience. I hope this answers your question. If you need additional information or further assistance, feel free to contact Barbara Mendieta at TNRCC by email (bmendiet@tnrcc.state.tx.us) or by phone at (512) 239-6086.

Question from Anonymous, Received 11/27/01:

What is the best way to incorporate a value below the detection limit when calculating a monthly average? For example, a plant collects four weekly effluent BOD samples during a month that the lab reports at the following values: 5 mg/l, 4 mg/l, 3 mg/l and "ND" (not detected). How do you calculate the average to report on the DMR? I have seen people use the detection limit, typically 2 mg/l for BOD, or zero for the ND value. I don't believe either of these is correct. By definition, ND means it is less than the detection limit and, to paraphrase Bobby Bare, "there ain't no zeroes." You do not want to omit a value as that would make your average look worse than actual plant performance (this is particularly critical when your permit limit is 5 mg/l and the detection limit is 2 mg/l). My approach has been to use one half the detection limit for an ND value, but I'm wondering how other people handle this. Response to Anonymous, Posted 11/28/01:

I have seen both of the methods used that you described, the detection limit and 1/2 the detection limit. I first determine how the data is to be used and its sensitivity. It is sometimes better to err on the side of the conservative, i.e.: to use the detection limit. I checked with the other lab personnel and they say the TNRCC B.O.D. guru (Terry Mills), says to use the detection limit. Most of time I see people using the 1/2 of the detection limit method. I have never used zero. You are right--there "aint no such thing". This has always been a question that has generated a lot of discussion. If the data is to be used for permit compliance it may be best to ask the inspector. But then I have done that and have gotten more than one answer.

Question by Anonymous, Received 11/26/01:

Are cities regulated by OSHA? Why or why not?

Response to Anonymous, Posted 11/27/01:

The question as to whether cities fall under the regulations of the Occupational Safety and Health Administration (OSHA), which is a Division of the U. S. Department of Labor, comes up periodically. A somewhat cursory review of their Internet Site - http://www.osha.gov - did not yield a definitive answer to the question, so we contacted the local OSHA Office. The local OSHA official stated that "municipalities are exempt from the standards." The why or why not simply has to do with the way the enabling legislation and the applicability rules are structured. The important thing for us to remember, however, is that the OSHA Standards will be taken as the "standard of care" in the courts. This means that our efforts to protect our employees from harm (in cases where wrongful injury or wrongful death is charged) will be judged alongside the OSHA Standards. For this reason, prudent managers will still want to comply with the OSHA standards.

Question from M. H., Received 11/25/01:

How do I obtain a water and wastewater license to distribute? How many hours are required for a Class B? How many for a Class C? Are there online classes to take? Do I have to have an apprentice card?

Response to M. H., Posted 11/27/01:

In Texas, there are separate Water Distribution and Wastewater Collection licenses. One may obtain a Class D Water Operator's License with no experience after completing the twenty hour Basic Water Operations Course and successfully completing the TNRCC licensing examination. The Class C Water Distribution license requires that one have a minimum of two years of experience and that they have completed sixty classroom training hours - namely the Basic Water Operations Course and the Water Distribution Course plus one elective course (which may be either Water Laboratory, Water Utility Safety, or Water Utility Calculations). The Class B Water Distribution license requires that one have a minimum of five years of experience in the field, and that they have completed one hundred hours of classroom training - namely the Water Distribution, Water Utility Safety, Pump and Motor Maintenance and Valve and Hydrant Maintenance Courses plus one elective (which may be either Water Utility Management, Water Utility Calculations, Chlorinator Maintenance or Water Laboratory.) The Class III Wastewater Collection license requires that one have a minimum of five years of experience in the field, and that they have completed one hundred hours of classroom training - namely the Basic Wastewater Operations, Wastewater Collection, Water Utility Safety and Pump and Motor Maintenance Courses plus one elective course (which may be the Water Utility Management, Water Utility Calculations or Pretreatment Facility Inspections Course). There are no online classes available at this time to our knowledge. The term "apprentice" is not common to the water utilities industry. The beginning or entry license is either the Class D License or the Class I License.

Question from B.D., Received 10/31/01:

We had an outside lab test done on a retained sample. The test was oil & Grease, the method used was EPA 1664 the sample was extracted with hexane, and the hexane extract when evaporated left a white crystalline substance in the flask. These white crystals have contributed to gravimetric weight gain that has led to high oil & Grease value. What method test can be done to identify this third substance? Is there another method for testing oil & Grease to EPA standard? What is this substance?

Response to B. D., Posted 11/19/01:

Sorry we took so long to respond. We had to consult outside help. Thanks Debbie!! The white substance is most likely a salt. In any procedure for oil and grease, the solvent, be it hexane or freon, is passed through a salt (i.e. sodium sulfate) to "dry it" or remove any water that may be held in the emulsification layer that forms between the sample and the solvent. The water is caught by the salt and the solvent passes through. If a large amount of water is passed through the salt it will dissolve the salt and carry it down to the dish or flask. When the water evaporates the salt crystals are left behind. Care must also be taken by the analyst so that when he or she is draining the hexane or freon through the salt that it is not done so rapidly that salt crystals are carried over the sides of the filter with the excess solvent. To determine if the crystals are salt, add a couple of drops of water and if it dissolves it is probably salt. If there is a lot of crystals, dissolve it in about 50 mL of deionized water. The deionized water should have a measurable conductivity if the crystals are salt. The best way to prevent too much water going on to the salt if you have a large layer of emulsification between the sample and the solvent is to change out the salt often. Don't let the salt in the filter become overwhelmed by the emulsification. Salt is cheap and its better to change it often. Samples from grease traps are notorious for developing thick emulsification layers. I have seen some pretty thick layers with food processing wastes.

Question from Anonymous, Received 11/16/01:

Back in June the TNRCC sent out a survey for operators to complete. It was stated that 2 credit hours would be given if this was completed. How can I verify that credit?

Response to Anonymous, Posted 11/19/01:

That survey was part of a Job/Task Analysis being conducted by TNRCC for Groundwater and Water Distribution personnel. You can verify whether you actually received the two hours of operator certification credit by contacting the TNRCC Operator Certification Section at (512) 239-6133 for water or (512) 239-0176 for wastewater.

Question from Anonymous, Received 11-15-01:

The TEEX Wastewater manuals state that TNRCC can take enforcement action in the case of an accidental discharge or an unauthorized discharge. What are the distinguishing differences between an accidental discharge and an unauthorized discharge?

Response to Anonymous, Posted 11-16-01:

Generally, the term "unauthorized discharge" is understood to include any discharge not authorized in one's discharge permit. It is a broad term that includes accidental discharges as well as a discharge knowingly caused by an operator or a facility owner. Enforcement action for accidental discharges would not be taken if an investigation determined that the circumstances that caused the discharge were beyond the control of the operator or owner. An example of this type of discharge would be an unauthorized discharge caused by "an act of God" or by the acts of someone else (a terrorist for example). Remember however, that an accidental discharge can lead to enforcement action in cases where the operator or owner failed to exercise due diligence to prevent the event that caused the discharge.

Question from B.K., Posted 11/12/01:

Regulations on Lazy River I.D. in Spring,Texas? Lazy River I.D. charges deposits that are not refunded until you disconnect your service. I heard that a law was passed that utility companies would not be able to hold a deposit that long or something pertaining to deposits. Plus once customer disconnects the interest amount is kept by the Company not the customer. I've looked all over Texas, P.U.C., Water Commission, and just can not find what I'm looking for. Help me please? If not try to point me in the direction I need to find my Answer. Thanks.

Response to B.K., Posted 11/13/01:

The answer to your question depends upon whether the Lazy River I.D. is a utility that is regulated under Chapter 291 of the Texas Administrative Code. Those rules apply to “Any person, corporation, cooperative corporation, affected county, or any combination of those persons or entities, other than a municipal corporation, water supply or sewer service corporation, or a political subdivision of the state, except an affected county, ….” The 291 rules require (in part) that “Each utility shall pay a minimum interest on all customer deposits at an annual rate at least equal to a rate set each calendar year by the Public Utility Commission of Texas in accordance with the provisions of Texas Civil Statutes, Article 1440a. Payment of the interest to the customer shall be made annually if requested by the customer, or at the time the deposit is returned or credited to the customer's account. Inquiries about the appropriate interest rate to be paid each year a deposit is held may be directed to the Water Utilities Division of the commission.” To determine whether the Chapter 291 rules apply in your particular instance, we would suggest that you contact Mr. Doug Holcomb with the Texas Natural Resource Conservation Commission (TNRCC) at (512) 239-1000.

Questions from Anonymous, Received 10/24/01:

What is the fraction of water usage in urban areas (in Texas) by households and by industry? How much revenue is collected in total by municipal water utilities in Texas?

Response to Anonymous, Posted 10/25/01:

Once again referring to the 1997 data on the Texas Water Development Board Site referenced below, the breakdown for the various water usage categories shown would yield the following: Municipal - 22.3%, Manufacturing - 9.9%, Power - 2.1%, Irrigation - 61.9%, Mining - 1.6%, and Livestock - 2.2%. We have not been able to locate data regarding the revenue generated from the various end users. You may be interested in a recent water rate survey completed by the Texas Municipal League. The survey reflects water/wastewater rates charged by many of the TML member cities. They can be reached at (512) 719-6300.

Question from Anonymous, Received 10/20/01:

How much water in total is provided by municipal water utilities in Texas?

Response to Anonymous, Posted 10/22/01:

We've not yet been able to find data on water usage in Texas for the year 2000. We did locate a chart that reflects historical water use data for 1980 through 1997 on the Texas Water Development Board's Internet Site ( http://www.twdb.state.tx.us/data/water_use/tex_hist.htm). That chart indicates that a total of 3,429,392 acre feet of water was used for municipal purposes in Texas in 1997. This comprises about 22% of the 15,391,103 acre feet total water usage for the State that year. For comparison, irrigation utilized 9,529,808 acre feet - or about 62% of the total. The expression one acre foot is simply the volume of a one acre area with water one foot deep over the area, and contains 325,828.8 gallons of water.

Question from B. D., Received 10/18/01:

What is the formula to find the volume in US gallons for a rectangular tank that contains Grit Trap waste?

Response to B. D., Posted 10/18/01:

The formula to determine the volume of a rectangular tank, in gallons and without regard for what the content may be, is the length (in feet) times the width (in feet) times the depth (in feet) times 7.48 (gallons per cubic foot) equals the volume in gallons. For example, "how many gallons are in a tank that is 8' wide, 15' long, and 6' deep?" would be solved as: 8 X 15 X 6 X 7.48 = 5,385.6 gallons.

Question from J. I., Received 10/08/01:

What is the formula I would use to estimate water loss when a water main is broken? I would assume that (1) line size, (2) line pressure, (3) length of time line was broken, and (4) a guesstimated fractional percentage of loss in the pipe would all be factors; but what would the formula be?

Response to J. I., Posted 10/11/01:

You seem to have a good grasp of what is involved in calculating the water loss. According to a Texas Water Development Board (TWDB) publication "Guidebook to Reducing Unaccounted-for Water", the formula is 2.8 times the area of the hole (in square inches) times the square root of 148 times the pressure (in pounds per square inch - psi) equals gallons per minute. For example, let's assume we have a hole that measures 1/8" X 1 1/4" in size, and that the line pressure is 50 psi. First we calculate the area as 0.125" X 1.25 = 0.156 square inches. We then plug the numbers in our formula thusly: 2.8 X 0.156 X Sq. Root of 7400 (148 X 50) - which is 86.02 = 37.57 gallons per minute. To continue, if the duration of the leak is estimated at 45 minutes, then the estimated water loss would be about 1690.65 gallons.

Question from B. D., Received 10/09/01:

I have a grease trap recycling plant using heat and centrifuging to separate the water from the grease. Before discharging, I find the TSS is enormously high. How do I get the TSS down to normal levels?

Response to B. D., Posted 10/10/01:

The answer to your question about solids removal depends on the type of solids in the waste stream. If the suspended solids are settleable, then some type of clarification (or settling) basin - prior to the heat/centrifuge treatment - should be effective in reducing the suspended solids. This would, however, generate a separate waste stream (the separated solids or "sludge") that would need to be treated and disposed of properly. Once stabilized, the solids could very likely be disposed of in a landfill in your area.

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