Section 64669.50 - Chemical ControlMunicipal wastewater used in a DPR project shall receive continuous treatment pursuant to this section prior to entering a water distribution system of a public water system.
(a) A treatment train shall consist of no less than three separate treatment processes, using no less than three diverse treatment mechanisms, for chemical reduction. The treatment train shall include the following treatment processes:(1) An ozonation process immediately followed by biologically activated carbon (ozone/BAC), unless exempted pursuant to subsection (c), that meets the criteria set forth in this section;(2) A reverse osmosis membrane process that meets the criteria set forth in this section; and(3) An advanced oxidation process that meets the criteria set forth in this section.(b) The sequence of processes required by subsection (a) in the treatment train shall be ozone/BAC followed by reverse osmosis membrane followed by advanced oxidation.(c) A continuous blending process that provides a municipal wastewater contribution (WWC) less than or equal to 0.10, may be used to substitute for the treatment in subsection (a)(1). For a continuous blending process with an approved WWC greater than 0.10, a DiPRRA shall provide treatment pursuant to subsection (a)(1) for a percentage of the municipal wastewater flow equal to or greater than: Click here to view image
(d) An ozone/BAC process shall be designed to provide no less than 1.0 log reduction of each of the following indicators: formaldehyde, acetone, carbamazepine, and sulfamethoxazole. (1) The ozonation process shall be designed to provide a ratio of the applied ozone dose to the design feed water total organic carbon (TOC) concentration greater than 1.0. A different design ratio may be used if it can be demonstrated that the ratio will achieve the reduction of the indicators carbamazepine and sulfamethoxazole at a pilot scale as part of the design of the ozonation process.(2) The BAC shall be designed with an empty bed contact time of at least 15 minutes. A different empty-bed contact time may be used if it can be demonstrated to achieve the reduction of the indicators formaldehyde and acetone at a pilot scale as part of the design of the BAC process.(e) The ozonation process and the BAC shall be individually validated to ensure that an ozone/BAC process designed pursuant to subsection (d) can reliably achieve the reductions of indicators at full-scale operation as follows. (1) The validation study shall demonstrate whether:(A) An ozonation process will provide no less than 1.0 log reduction measured across the ozonation process for each of the following indicators: carbamazepine and sulfamethoxazole; and(B) A BAC will provide no less than 1.0 log reduction measured across the BAC for each of the following indicators: formaldehyde and acetone.(2) A DiPRRA shall submit a validation study protocol for the ozone/BAC process that complies with this subsection to the State Board for review and written approval prior to conducting the validation study. The validation study protocol shall include challenge tests, using formaldehyde, acetone, carbamazepine, and sulfamethoxazole, to demonstrate that the proposed ozone/BAC process will reliably achieve the minimum 1.0 log reduction of each indicator under the proposed normal full-scale operating conditions of the ozone/BAC process. The validation study protocol shall include proposed surrogate and/or operational parameters to be used in the validation study. The ozone/BAC process shall be re-validated when the full-scale operating conditions or control strategy are inconsistent with the previous validation study conditions.(3) The DiPRRA shall submit a validation study report, including all results generated by the validation study, to the State Board as part of the engineering report prepared pursuant to section 64669.75. The validation study report shall identify the chemical control point(s) and the surrogate and/or operational parameter(s) and establish the critical limit(s) for the surrogate(s) and/or operational parameter(s) that indicate whether:(A) For the ozonation process, the minimum 1.0 log carbamazepine and sulfamethoxazole reduction design criteria are being met during full-scale operation. At least one surrogate or operational parameter shall be capable of being monitored continuously and recorded and have associated alarms that indicate when the ozonation process is not operating as designed.(B) For the BAC, the minimum 1.0 log formaldehyde and acetone reduction design criteria are being met during full-scale operation. At least one surrogate or operational parameter shall be capable of being monitored continuously and recorded and have associated alarms that indicate when the BAC is not operating as designed.(f) During full-scale operation of an ozone/BAC process designed pursuant to subsection (d) and validated pursuant to subsection (e), a DiPRRA shall continuously monitor and record the surrogate and/or operational parameters, record when the critical limits established pursuant to subsection (e)(3) are exceeded, and continuously monitor the ozonation process feedwater for nitrite, according to an approved operations plan pursuant to section 64669.80.(g) A reverse osmosis membrane selected for use shall meet the following requirements:(1) Each membrane element has achieved a minimum rejection of sodium chloride of no less than 99.0 percent and an average (nominal) rejection of sodium chloride of no less than 99.2 percent, as demonstrated through Method A of ASTM International's method D4194-23 Standard Test Methods for Operating Characteristics of Reverse Osmosis and Nanofiltration Devices (February 2023), which is hereby incorporated by reference, using the following substitute test conditions:(A) A recovery of permeate of no less than 15 percent,(B) Sodium chloride rejection is based on three or more successive measurements, after flushing and following at least 30 minutes of operation having demonstrated that rejection has stabilized,(C) An influent pH no less than 6.5 and no greater than 8.0,(D) An influent sodium chloride concentration of no greater than 2,000 mg/L, to be confirmed prior to the start of testing, and(E) An applied pressure no greater than 225 pounds per square inch (psi); and(2) During the first twenty weeks of full-scale operation, the membrane produces a permeate with no more than five percent of the sample results having TOC concentrations greater than 0.25 mg/L (or an alternative surrogate parameter and corresponding limit approved by the State Board), as confirmed through monitoring no less frequent than weekly.(h) For the reverse osmosis treatment process, a DiPRRA shall propose as part of the engineering report prepared pursuant to section 64669.75 ongoing performance monitoring using at least one surrogate and/or operational parameter that is capable of being monitored continuously and recorded and have associated alarms that indicate when the integrity of the reverse osmosis membrane has been compromised. The proposal shall identify the chemical control point and the surrogate(s) and/or operational parameter(s) and establish the critical limit(s) for the surrogate(s) and/or operational parameter(s) that indicate when the integrity has been compromised.(i) During full-scale operation of the reverse osmosis treatment process, a DiPRRA shall continuously monitor and record the surrogate and/or operational parameter(s) that indicate when the integrity of the process has been compromised and record when the critical limits established pursuant to subsection (h) are exceeded, according to an approved operations plan pursuant to section 64669.80.(j) A DiPRRA shall track the TOC performance of the reverse osmosis membranes pursuant to subsections (j)(1) and (j)(2) and report findings to the State Board in the monthly compliance report prepared pursuant to section 64669.95.(1) If the combined reverse osmosis permeate TOC concentration exceeds 0.15 mg/L continuously for more than 120 hours, a DiPRRA shall investigate the integrity of the reverse osmosis treatment, perform a conductivity profile to identify the underperforming reverse osmosis vessel or reverse osmosis element, and take corrective action.(2) If the combined reverse osmosis permeate TOC concentration exceeds 0.1 mg/L continuously for more than 24 hours, a DiPRRA shall collect a grab sample of the reverse osmosis permeate and perform a 5-day total trihalomethane formation potential study.(k) An advanced oxidation process shall be designed to provide no less than 0.5 log reduction of the indicator 1,4-dioxane. The advanced oxidation process shall be validated to demonstrate that the advanced oxidation process can reliably achieve no less than 0.5 log reduction of the indicator 1,4-dioxane. (1) The DiPRRA shall submit a validation study protocol that complies with this subsection to the State Board for review and written approval prior to conducting the validation study. The validation study protocol shall include challenge tests, using 1,4-dioxane, to demonstrate that the proposed advanced oxidation process will reliably achieve the minimum 0.5 log reduction under the proposed normal full-scale operating conditions of the advanced oxidation process. The validation study protocol shall include proposed surrogate and/or operational parameters to be used in the validation study. The advanced oxidation process shall be re-validated when the full-scale operating conditions or control strategy are inconsistent with the previous validation study conditions.(2) The DiPRRA shall submit a validation study report, including all results generated by the validation study, to the State Board as part of the submittal of the engineering report prepared pursuant to section 64669.75. The validation study report shall identify the chemical control point(s) and the surrogate(s) and/or operational parameter(s) and establish the critical limit(s) for the surrogate(s) and/or operational parameter(s) that indicate whether the minimum 0.5 log 1,4-dioxane reduction design criterion is being met. At least one surrogate and/or operational parameter shall be capable of being monitored continuously and recorded and have associated alarms that indicate when the advanced oxidation process is not operating as designed.(l) During full-scale operation of the advanced oxidation process designed and validated pursuant to subsection (k), the DiPRRA shall continuously monitor and record the surrogate and/or operational parameter(s) established pursuant to subsection (k)(2) and record when the critical limits established pursuant to subsection (k)(2) are exceeded, according to an approved operations plan pursuant to section 64669.80.(m) The design and operation of the entire treatment train used to comply with the requirements in this Article and connected facilities such as storage tanks, detention basins, reservoirs, related pipelines, and water conveyance shall provide continuous mixing of the flow along the path of flow between the terminus of the wastewater collection system and the entry point to the drinking water distribution system sufficient to attenuate a one-hour elevated concentration of a contaminant in the municipal wastewater by a factor of ten. Mixing that occurs between the wastewater treatment plant inlet chamber and the DPR project finished water may be used to meet this requirement.(n) The DiPRRA shall establish a TOC chemical control point and a control point monitoring location that provides representative sampling of the advanced treated water prior to distribution. To determine compliance with subsections (n)(1) through (n)(4), TOC shall be monitored continuously and the TOC concentration shall be recorded no less than once every fifteen minutes. TOC of wastewater origin in excess of 0.5 mg/L shall be prevented from entering the distribution system. The TOC concentration at the TOC chemical control point shall not exceed the TOC critical limit as follows: the TOC concentration shall not exceed a TOC critical limit equal to 0.5 mg/L in the advanced treated water prior to distribution, unless adjusted pursuant to subsections (n)(1) and/or (n)(2). (1) When DPR project water is being blended prior to distribution with an untreated source of water previously approved by the State Board or a finished water previously approved by the State Board in accordance with sections 116525 through 116550 of the Health and Safety Code, the TOC concentration in the advanced treated water prior to blending shall not exceed a TOC critical limit equal to 0.5 mg/L divided by the WWC. The TOC critical limit must always be based on the current WWC.(2) Attenuation of elevated TOC concentration of limited duration with mixing in a reservoir downstream of the advanced treatment may be used to temporarily increase the TOC critical limit in section (n) and/or subsection (n)(1). The magnitude and duration of proposed alternative TOC critical limit must be justified by hydrodynamic modeling, tracer testing, and the diluent capacity of the reservoir, to demonstrate that the TOC of wastewater origin is no more than 0.5 mg/L in the water entering the distribution system. The proposed alternative TOC critical limit, hydrodynamic modeling, and tracer testing must be reviewed by an independent advisory panel pursuant to section 64669.120.(3) If the TOC critical limit pursuant to section (n), subsection (n)(1) or subsection (n)(2) is not met, the DiPRRA shall take action to immediately discontinue delivery of non-compliant DPR project water to any distribution system. The DiPRRA shall notify the State Board and each public water system directly receiving DPR project water within 24 hours of knowledge of a failure to meet the TOC critical limit.(4) If the TOC concentration exceeds one half the TOC critical limit pursuant to section (n), subsection (n)(1), or subsection (n)(2) continuously for more than 60 minutes, a DiPRRA shall conduct an evaluation of the treatment system, initiate a source control investigation pursuant to the approved joint plan, collect samples for laboratory analysis to investigate the cause(s) of the elevated concentration, and include the results in the monthly compliance report submitted pursuant to section 64669.95.(o) If for more than 10 percent of the time the treatment train was producing water in a calendar month there is any treatment process pursuant to subsections (a) and (b) that is not operating in compliance with its associated critical limits pursuant to subsections (e), (h), or (k), a DiPRRA shall: (1) Evaluate the cause(s) of the failure to achieve the critical limit(s) pursuant to this subsection;(2) Take corrective action; and(3) Summarize the evaluation and corrective actions taken in the monthly compliance report submitted pursuant to section 64669.95.(p) Within sixty (60) days after the first 12 months of full-scale operation, the DiPRRA shall submit a report to the State Board that complies with this subsection. (1) For the reverse osmosis process, the report shall describe the effectiveness of the treatment, process failures that occurred, and actions taken when membrane integrity monitoring conducted pursuant to subsection (i) indicated that process integrity was compromised; and(2) For the ozone/BAC and the advanced oxidation processes, the report shall include: (A) Results of surrogate and/or operational parameter monitoring conducted pursuant to subsections (f) and (l);(B) A description of the efficacy of the surrogate and operational parameters to reflect the reduction criteria for carbamazepine and sulfamethoxazole for the ozonation process, formaldehyde and acetone for the BAC, and 1,4-dioxane for the advanced oxidation process; and(C) A description of actions taken, or yet to be taken, if the ozone/BAC process or advanced oxidation process were not operating in accordance with the operations plan pursuant to section 64669.80 during the first 12 months of operation.(q) A DiPRRA shall evaluate data collected on treatment byproduct precursors and treatment byproducts pursuant to sections 64669.60(b), 64669.65(b), and 64669.75(c)(2), and options for optimizing operation to minimize production of treatment byproducts. The DiPRRA shall include a plan for optimization operation to minimize production of treatment byproducts in the operations plan prepared pursuant to section 64669.80.(r) A DiPRRA may use an alternative to a treatment or treatment sequence requirement in subsections (a) through (l) and (o) if the DiPRRA: (1) Demonstrates to the State Board that the proposed alternative provides an equivalent or better level of performance with respect to the efficacy and reliability of the reduction of contaminants that pose a risk to public health, and assures an equivalent or better level of protection to public health;(2) Identifies the chemical control point(s) and the surrogate and/or operational parameter(s) and establish the critical limit(s) for the surrogate(s) and/or operational parameter(s); and(3) Receives written approval from the State Board prior to implementation of the alternative, with approval based on compliance with this subsection.(s) A demonstration pursuant to subsection (r)(1) shall include a review of the proposed alternative by an independent advisory panel pursuant to section 64669.120. The panel shall consider:(1) whether the level of public health protection being provided by an alternative to a treatment or treatment sequence is equivalent to or better than the public health protection from the required treatment or treatment sequence;(2) how the level of treatment performance and reliability for the proposed alternative will be measured;(3) how the alternative affects downstream treatment process(es) and distribution system water quality;(4) how the alternative affects the fate of wastewater contaminants and treatment byproducts through the treatment train; and(5) how the alternative affects treatment train reliability.(t) An alternative to a requirement in section (a) shall comply with the following: the treatment train with the alternative shall consist of no less than three separate treatment processes, using no less than three diverse treatment mechanisms, for chemical reduction.Cal. Code Regs. Tit. 22, § 64669.50
Note: Authority cited: Sections 13521 and 13561.2, Water Code; and Sections 116271, 116350 and 116375, Health and Safety Code. Reference: Sections 13520, 13522, 13561, 13561.2 and 13567, Water Code; and Sections 116275, 116360, 116365, 116375, 116385, 116400, 116551, 116555 and 116735, Health and Safety Code.
1. New section filed 8-6-2024; operative 10/1/2024 (Register 2024, No. 32).