2 comments
Good Afternoon,
On behalf of the Virginia Restaurant, Lodging & Travel Association and the hospitality and tourism industry, I would like to take a moment to request that the board retain the current regulations governing tourist establishment swimming pools as currently written.
All the best,
Robert B. Melvin
Director of Government Affairs
Virginia Restaurant, Lodging & Travel Association
5101 Monument Ave. Suite 206
Richmond, VA 23230
(o) 804-288-3065
We would like to offer the following suggestions for changes to 12 VAC5-460 Regulations governing tourist establishment swimming pools and other public pools. Added text is underlined, deleted text is in crosshatch font.
12VAC5-460-260. Chemical Testing Equipment.
12VAC5-460-270. Operating Records.
12VAC5-460-260. Chemical Testing Equipment.
Each swimming pool shall be provided with satisfactory equipment for the determination of hydrogen-ion concentration (pH) ranging from 6.8 to 8.0. Satisfactory equipment shall also be provided for the determination of residual chlorine content ranging from 0.0 to 10.0. For pools containing cyanuric acid, satisfactory equipment shall also be provided for the determination of cyanuric acid content ranging from 0 to 100 ppm.
12VAC5-460-270. Operating Records.
Acceptable records of the operation of the swimming pool shall be maintained. These records shall include pH levels, free chlorine residual, cyanuric acid (when used), water clarity, cleanliness, and such other things as may be required for the health and safety of the bathers. These records shall be kept on file for a period of one year
Because cyanuric acid (CYA) affects the concentration of active chlorine disinfectant (hypochlorous acid, HOCl), pools using stabilized sanitizers or any other form of CYA should also be required to have CYA testing equipment and maintain records of CYA concentrations.
The required range for chlorine was increased to 0-10 ppm to be consistent with 12VAC5-462-290.
12VAC5-460-280. Disinfection.
For minimum chlorine residuals, we would like to offer the following three options for discussion:
Option 1
12VAC5-460-280. Disinfection.
The chlorination equipment shall be operated so as to maintain a free chlorine residual
content of not less than 0.5 1.0 ppm at all points throughout the swimming pool water when there are bathers present. If cyanuric acid is used, the minimum shall be 2.0 ppm.
Option 2
12VAC5-460-280. Disinfection.
The chlorination equipment shall be operated so as to maintain a free chlorine residual
content of not less than 0.5 1.0 ppm at all points throughout the swimming pool water when there are bathers present. For pools using cyanuric acid, the minimum chlorine shall be as follows:
|
Minimum chlorine residual, ppm |
Range CYA, ppm |
|
2 |
1 to 30 |
|
3 |
31 to 60 |
|
4 |
61 to 90 |
Option 3
12VAC5-460-280. Disinfection.
The chlorination equipment shall be operated so as to maintain a free chlorine residual
content of not less than 0.5 1.0 ppm at all points throughout the swimming pool water when there are bathers present. For pools using cyanuric acid, the chlorination equipment shall also be operated so as to maintain a free chlorine residual content of not less than one fifteenth the total cyanuric acid concentration, equivalent to a CYA: free chlorine ratio that does not exceed 15:1.
The 1.0 ppm minimum without CYA and the 2.0 ppm minimum in the presence of CYA in Option 1 are from the current 2018 edition of the Model Aquatic Health Code (MAHC). Justification of these values may be found in the Annex to the MAHC.
Option 2 was taken from the Model Aquatic Health Code change request which received the majority of votes during the latest revision cycle (CR 5.7.3.1.1.2.2-0001). Since the 2021 MAHC has not yet been published, it is not known whether CDC will accept the CMAHC vote.
As for the 15:1 cyanuric acid to free chlorine ratio in Option 3, please note that the Council for the Model Aquatic Health Code (CMAHC) has a committee for investigating the effects of cyanuric acid on disinfection. The CMAHC Chlorine Stabilizers Ad Hoc Committee has published a paper (Falk 2019) that has the following conclusions:
Although we cannot directly measure HOCl concentrations with pool test kits, the HOCl concentration can be estimated using a ratio of free chlorine measured by DPD (DPD-FC) and CYA. As shown in the following table, the HOCl concentration is constant with constant CYA: DPD-FC ratio:
|
CYA, ppm |
DPD-FC, ppm |
HOCl, ppm |
|
20 |
1 |
0.02 |
|
40 |
2 |
0.02 |
|
60 |
3 |
0.02 |
|
80 |
4 |
0.02 |
The committee recommends setting a maximum CYA:DPD-FC ratio as a way to ensure a minimum HOCl concentration.
The following table shows the HOCl concentrations for various CYA:DPD-FC ratios at pH 7.5:
|
CYA, ppm |
DPD-FC, ppm |
HOCl, ppm |
|
0 |
1 |
0.49 |
|
15 |
1 |
0.026 |
|
20 |
1 |
0.020 |
|
30 |
1 |
0.013 |
|
45 |
1 |
0.0086 |
The MAHC currently has a minimum 2 ppm DPD-FC when CYA is used, and a 90 ppm CYA maximum. This is essentially a 90:2, or 45:1 ratio, which results in a minimum HOCl concentration of 0.0086 ppm.
The debate has been about which ratio (or HOCl concentration) to choose. Of course there is no perfect method for drawing a line in the sand for an issue that the industry has been debating for decades. However, we believe that the strongest argument amongst the various proposals is the comparison to monochloramine.
Monochloramine was chosen as a standard because it is commonly used in drinking water treatment where contact times through water distribution systems can be very long, but it is not considered a sufficient disinfectant for pool water treatment where bather-to-bather disease transmission can occur very quickly. Monochloramine has the added advantage that there is a wealth of data for it and EPA has published standard CT values (CT = concentration x time needed to achieve inactivation) for its use in drinking water. The EPA values for Giardia were used in the comparison because this organism is relevant to recreational water and has a larger CT value than typical bacteria. Following is a table from EPA comparing the Giardia CT values for free chlorine and monochloramine.
Table from EPA LT1ESWTR Disinfection Profiling and Benchmarking, 2003 EPA 816-R-03-004
|
Pathogen |
CT Free Chlorine, ppm min |
CT Chloramine, ppm min |
|
Giardia |
45 |
750 |
The supplemental material of the Falk 2019 publication shows that a limiting CYA/FC ratio of 15:1 would ensure that the inactivation time for Giardia in a stabilized pool is at least equivalent to 1 ppm monochloramine.
When setting a CYA limit, it is important to consider both the benefits and drawbacks of using it. In 1974 Canelli studied the stabilizing effect of CYA on chlorine residuals. His data shows that the largest effects from CYA are seen at low concentrations. The data also show that a 15:1 ratio is sufficient for stabilizing chlorine residuals.
Drawing a line in the sand for setting a CYA limit in pools is difficult because it is difficult to determine how much is enough to stabilize chlorine residuals, and how much is too much for sacrificing chlorine efficacy. Chlorine stabilization data will vary with sunlight intensity and water chemistry. Likewise, chlorine kill rates will vary depending on many factors, including organism type and water chemistry.
We would like to propose that the limit should be set so that the killing power of chlorine with CYA will not be less than that of combined chlorine (e.g. monochloramine) for Giardia. In aquatic venues, the killing power of monochloramine is generally not considered sufficiently effective for pathogens like Giardia, so we should ensure that the efficacy of chlorine is not compromised by the use of CYA to the point where chlorine is less effective than monochloramine.
12VAC5-460-290. Alkalinity.
The hydrogen-ion concentration should be maintained at between 7.2 and 7.8 or above.
The maximum pH value is consistent with 12VAC5-462-290, the current MAHC and industry standards.
12VAC5-460-300. Filtration; Water Clarity.
Chemicals other than chlorine, sodium or calcium hypochlorite, lime, soda ash, sodium bicarbonate, muriatic acid, sodium bisulfate, calcium chloride, and aluminum sulfate shall not be used to treat swimming pool water without permission.
The basic chemicals needed to balance water according to the Langelier Saturation Index include those needed to adjust pH up (lime, soda ash), pH down (muriatic acid, sodium bisulfate), alkalinity (soda ash, sodium bicarbonate) and calcium (calcium chloride).
In addition to these specific changes, we would also recommend that you consider adding a section for fecal/vomit contamination response based on CDC guidance in MAHC section 6.5.3.
Thank you for your consideration of these proposed changes. Please let us know if you have any questions or require any further information.
Best regards,
Ellen Meyer
Sigura
1200 Lower River Rd NW
Charleston, TN 37310
References
Canelli, E.D., Chemical, bacterillogical, and toxicological properties of cyanuric acid and chlorinated isocyanurates as applied to swimming pool disinfection, a review, AJPH February 1974, 64(2) 155-162, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1775396/ .
Centers for Disease Control and Prevention (CDC), Model Aquatic Health Code, 2018, https://www.cdc.gov/mahc/editions/current.html .
EPA Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) Disinfection Profiling and Benchmarking Technical Guidance Manual, 2003 EPA 816-R-03-004, https://www.epa.gov/dwreginfo/long-term-1-enhanced-surface-water-treatment-rule-documents .
Falk, R.A., Blatchley, E. R., Kuechler, T. C., Meyer, E. M., Pickens, S.R., Suppes, L. M., Assessing the Impact of Cyanuric Acid on Bather’s Risk of Gastrointestinal Illness at Swimming Pools, Water 2019, 11(6), 1314; doi:10.3390/w11061314, https://www.mdpi.com/2073-4441/11/6/1314