OC Laboratory

Event CoordinatorEvent Vice-Coordinator
Melodi Clark
Surveillance Lab Manager
Wastewater Chemist III
City of Columbus



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2025 Laboratory Event Description  *UPDATED 2/14/25

2025 Laboratory Judging Sheets *Coming Soon
The judging sheets are provided primarily for event coordinators and judges information only. They are not part of the procedures or the rules of the event. They are for reference only and do not govern; the event descriptions govern. They are updated periodically and are subject to change at any time, without notice. They may not be used in any form of protest or question. There may be actions that are penalties that are not explicitly listed as an example on the penalty sheet.

Laboratory Event Tutorial*NEW
Tutorials should be used as an overall suggestion not 100% accurate
Bench Sheet and CalculationsEquipment PurchaseTables
Chlorine Bench Sheet*NEWDiscount Codes for Hach purchases (20% off) *NEW

US - LABTEST
Canada – LABTESTCA

Table Layout (New Layout Coming Soon)
Photo is two set ups back to back. New WEFTEC  setup will be tables in a row – left to right – at an angle.  Like an arrowhead.



Phosphate Bench Sheet*NEW


Calculations for the PO4 and CL2 solution/concentration












**These videos are for informational purposes only and may not necessarily be a clean run.

Ask A Question

Questions accepted up until  9/23/25.  Questions can be asked at the pre-competition meeting on Monday, September 29, 2025 in Chicago, Illinois.

QuestionAnswerDate
Approximately when might we see the new Lab Event procedure? We know you are working hard on it, but it would be very helpful to have an ETA, just so we don't have to keep checking the site every few days. Thank you!We should have it up by end of next week 1/24/251/14/25
Can you explain/demonstrate the math formula used to calculate the PO4 and CL2 solution/concentration?Click here for the written calculations.1/26/25
The procedure mentions two tables, one with the spectrophotometer. Are both tables the same size, (dimensions)? Or will both analyses be performed on one table and the spectrophotometer will be a standalone on the other table?

We will using the lab tables that we have had for the past lab events.  There will be 2 tables so each test can performed on its own table with the spec on 1 of the table to perform the readings. The table dimensions are 96”L x 30”W x 36”H.

1/28/25
The equipment list includes trays for glass ware and waste containers. Is this equipment located on table #2?  

The trays will be on the opposite table from the where the Hach DR3900 spec is located.

1/28/25
For lab supply ordering/setup - The material list notes you need 1x 4L bottle of DI water and one 10L carboy for dispensing the DI water, but the table layout indicates 2x 4L bottles of DI water. Will the DI water be in a carboy for easier dispensation or will we need to order 2x 4L DI bottles to pour directly out of?

The 2 4L bottles will be dumped into the 10L carboy for ease of use.

1/29/25
Will there be a "OPS Challenge Kit" available for purchase through HACH? The vendor booth at WEF said there would be, but I'm not seeing anything about it posted and our sales rep hasn't heard anything either. We'd like to order ASAP so we can get practicing.

There is no kit from Hach but they have provided these discount codes that can be used every time you order it gives you 20% off.

US - LABTEST

Canada – LABTESTCA

1/30/25
Is there going to be a new table layout, it still shows the old layout

Yes there will be a new table layout coming soon.

1/30/25

1.  Will the DR3900 be turned on during setup? 

2.  Will the tap water be in a carboy the same as the DI water? 

3.  Will there be a 500 ml wash bottle with tap water to enable rinsing or will it be from the 4l container or carboy? 

1.  Yes it will be turned on

2.  Yes there will be 2 carboys 1 with DI water and 1 with Tap water. They will be labeled.

3.  No the tap water will go into a 250 ml beaker for use.  *UPDATED*		1/31/25
UPDATED 2/7/25
1.  For the Chlorine Standard Additions, are we pulling from the chlorine ampoule standard, or the standard solution created in the first part?

2.  How many 500 mL wash bottles are on the table?   The instructions say 2 DI wash bottles, but the questions above say there will also be a Tap wash bottle? 		1.  You are pulling form the standard solution created in the first part of the Chlorine procedure.

2.  I have updated my answer. The tap water will come out of a 250 ml beaker not a 500 ml wash bottle.

2/7/25
1.  How many DI carboys will be on the table? In the layout provided in the description it shows two of them, however, questions have made it seem as though there will only be one. 

2.  On the phosphate analysis sheet, in the space "unknown" is this the 10, 15, 20, or 30 concentration and then the space "calculated unknown" would be the result of the first sample multiplied by 5, correct? 

1.  There will be 2 carboys


2.  Yes you are correct the unknow will be one of the 10, 15, 20 or 30 and the calculated unknown will be the unknown multiplied by 5.

2/11/25
1.  Will the wash bottles be filled before the run? 

2.  In the description and previous questions it states that in the second round of chlorine testing you add in 0.1, 0.2, 0.3 to 10mL of DI water from the standard solution you mix in the beginning. However, running this way yields no residual and in the video it shows the standard additions coming from the chlorine beaker containing the standard from the ampule. Which beaker is the correct one to be pulling for the additions, the chlorine beaker containing the ampule or the standard solution mixed at the beginning?

1.  Yes they will be filled before by the lab coordinators

2.  The beaker containing the what you poured out of the ampule is where you pull for the second round of chlorine testing.


How close do we have to get to the nominal concentrations to get bonus time? 

Within 10% of target = 60 seconds back. Within 10-20% of target = 20 seconds back. Greater than 20% of target no time back2/11/25

1. For the 2ppm phosphate standard, the procedure indicates rinsing the 100mL volumetric flask and 100mL graduated cylinder 3x with DI, then rinsing 1x with the unknown standard. Wouldn't rinsing last with this standard potentially introduce contamination and an artificially inflated dilution concentration?

2. When rinsing the Cl2 glassware, the procedure indicates rinsing 3x with tap water (from a 250mL beaker) and 3x with DI for everything used in the event.   This equates to around 48 rinses per run before any dilutions can be created. Is it possible we could investigate removing the tap water rinse?

3. When rinsing the Cl2 sample cells after the first set of readings, does the sample cell need to be rinsed with tap water 3x and DI water 3x as previously stated? If not, how many times does it need to be rinsed with DI water? 

4. Will we be required to label any of the TNT or Cl2 sample vials? 

5. Will we be required to label the 100mL volumetric flasks? 

1.  This is standard lab practice to rinse with the standard. It will not artificially inflate the dilution concentration.

2.  The procedure as written will be followed.  If after going through competitions we feel things need changed, we will do so.

3.  The Cl2 sample cells needs to be rinsed in between each new sample that is being poured into it. The cell should be rinsed 3x with DI water in between each new sample being poured into the Cl2 sample cell.

4.  No.

5.  Yes

2/11/25

For phosphate sample with unknown concentration, do we need to rinse the STD beaker with DI water, the dilution or both? Or do we not rinse at all.  

No the beaker is not rinsed.2/11/25

1.  Labeling step 5: Does the DI beaker need to be rinsed prior to adding DI water to it? 

2.  Phosphate sample with unknown concentration step 1e: Does the "STD" labeled beaker need to be rinsed prior to transferring the solution to it? If so, DI rinse and/or solution rinse? 

3.  Phosphate Standard Solution step 3 b: Does the solution B need to mixed 5 times like it was for the initial sample with unknown concentration? 

1.  Yes rinse 3 times with DI water

2.Yes it needs rinsed with solution once before filling with the solution.

3.  Yes it needs mixed 5 times inverted at a 90 degree angle.


2/12/25

In one of the previous questions it is mentioned that we need to label the 100ml volumetric flask, what do they need to be labeled as? 

For the phosphate 100 ml flask should be labeled 2 mg/L PO4 for the Chlorine 100 ml flask it should be labeled 1 mg/L Cl22/12/25

What will the volumetric flasks be labeled? 

For the phosphate 100 ml flask should be labeled 2 mg/L PO4 for the Chlorine 100 ml flask it should be labeled 1 mg/L Cl22/12/25

1.  Can we label the beakers during set up? 

2.  Can we unscrew phosphorous test tubes during set up? 

1.  No this can’t be done during set up

2.  No this can’t be done during set up		2/12/25
1.  Are we able to place pipette tips on the pipettes themselves during set up? 

2.  We rinse the tap beaker with tap water then DI water then fill with tap?..... 		1.  No this can’t be done during set up.

2.  Yes this is normal lab practice for this test.		2/12/25
Instructions say to pipet from the chlorine standard beaker into the 3 cells. When we do this, we can not replicate the results from the tutorial video however when we use the Cl2 beaker we get the results of the video. Please explain.  This question was asked a little differently but the answer is still the same.  The beaker containing the what you poured out of the ampule is where you pull for the second round of chlorine testing that go into the 3 cells.2/13/25
Instructions for chlorine standard additions, #4 say to add powder pillows to four sample cells. Are we adding a pillow to the blank? No, you do not add the pillow packet to the blank.  *UPDATED*2/14/25
*UPDATED 2/17/25

What exactly can't we do in setup? Setup instructions are not listed in the procedure. Ex. remove powder pillows, pipette tips, test vials, etc. from their respective bags/boxes. 

The procedure has been updated to include setup instructions.

2/14/25
When will we be getting a full table layout of what we’ll have on both tables?The table layout will be available after the South Carolina event which is March 9th.2/18/25
When will the new Table Layout be posted? The table layout will be available after the South Carolina event which is March 9th.2/18/25
1. Can I use DI wash bottle to fill Volumetric flask or do I have to use the DI beaker with DI water in it to transfer into Volumetric flask?

2. Can I use the 10L carboy to fill the graduated cylinder with DI water, if not can I use the wash bottle or is the DI beaker with DI water only used for filling?

3. After phosphate unknown sample is done do I need to repeat all the rinsing instructions for the know sample or is the initial rinse from the unknown sample sufficient for the run? 

4. If DI beaker is used to fill, do I need to re rinse every time after beaker is empty and refilling is needed? 		1.  Yes

2.  Yes

3.  Yes you need to repeat the rinsing.

4.  No		2/18/25

1. Since there will be two carboys on the table, will the two 4L bottles of deionized water and the one 4L bottle of tap water still remain on the table? 

2. For clarification, this question was previously answered differently twice: Should we rinse the STD-labeled beaker with the unknown phosphate sample, deionized water, or both?

3. Is there an update on the table layout, and will the tables be the same size? 

1.  No they will be removed for the event

2.  Rinse the STD beaker 3x with DI water and 1x with the unknown phosphate sample.

3.  The table layout will be available after the South Carolina event which is March 9th.		2/18/25
The above questions clarify that the Chlorine Standard Additions in the second part of the Chlorine procedure must be made using the ampoule "Cl2" beaker. Under #2 of the Chlorine Standards Addition section of the rules, it still states, "...add 0.1 mL of the chlorine standard from the STD beaker to one of the cells..." These two statements are contradictory. Therefore, will you update the rules to reflect that we must pull from the "Cl2" beaker for the Chlorine Standard Additions in the second part? The procedure has been updated to say pull from the “CL2” beaker for the standard additions.2/18/25

Question #1 - Do all glassware used for the stock solution and standard solutions need to be dried after being rinsed with D.I. water? 

Question #2 - We know that the 2025 lab event will include two chemical analyses, Phosphate and Total residual chlorine. Both TDS and TSS analyses no longer part of this event? Can you clarify why a 50g calibration mass, and an analytical balance are on the material list? 

1.  No they don’t need dried.


2.  These are on the list for future use in this event when we add more items into the event in the next few years.		2/18/25
1. The 2 mg/L PO4 standard procedures mention using the graduated cylinder to measure and add your calculated aliquot of unknown sample to add to the volumetric. Will the pipettes not be used for this step? Or is the volume supposed to be taken from the unknown sample and added to the graduated cylinder via pipette before adding to the volumetric? Will it be allowed to pipette directly into the volumetric to ensure accuracy of the standard? 

2. What type of bottle and how much volume of unknown sample will be provided? The procedure mentions mixing the standard and the table diagram shows where it starts, but I can’t find a mention of what type of bottle this is.  		1.  You are measuring 20 mls of the unknown.  You can pour it directly into the graduated cylinder or use a pipette to transfer the 20 mls it is up to you.


2.It will be in a volumetric flask.		2/20/25
Question #1 - Do all glassware used for the stock solution and standard solutions need to be dried after being rinsed with D.I. water?
Question #2 - We know that the 2025 lab event will include two chemical analyses, Phosphate and Total residual chlorine. Both TDS and TSS analyses no longer part of this event? Can you clarify why a 50g calibration mass, and an analytical balance are on the material list?
1.  No they don’t need dried.

2.  These are on the list for future use in this event when we add more items into the event in the next few years.
2/21/25