City approves $41K for Nitrification Action Plan
GONZALES — City council last week approved a $41,000 expenditure to contract with LNV, Inc, to develop and implement a Nitrification Action Plan (NAP), which will help the city water works to discover if nitrification is occurring in city water and help to minimize or prevent the nitrification with a plan of action to address nitrification triggers and event indicators in the distribution system.
The contract also addresses submission of the plan to the Texas Commission on Environmental Quality (TCEQ), a revised Disinfection Contact Time (CT) Study, as well as the approval of an Alternate Combined Filter Effluent (CFE) monitoring location, in response to a TCEQ Notice of Violation in June.
The CT study is an evaluation of a water treatment plant’s disinfection process based on the concentration (C) of the disinfectant and the theoretical contact time (T) of the disinfecting chemical during the treatment process. The purpose of the CT study is to: identify the number of disinfection zones at a water plant; determine the effective contact time provided in each zone; determine if disinfection requirements are being met; and, provide parameters used to determine daily compliance with disinfection requirements.
Nitrification is a concern for public water systems because it can cause a loss of disinfectant residual and allow bacteria regrowth, which can lead to elevated levels of fecal coliform units, as well as other virus and bacteria leading to warning to boil drinking water and be detrimental to human health. Nitrification can also raise nitrate and nitrite levels, which both have established Maximum Contaminant Levels (MCL's) and are regulated by TCEQ.
The NAP created for the city will follow trends in monitoring data, steps to prevent an event and actions to wake in the case of a nitrification event.
The development an implementation of a NAP is completed through a seven-tier outline of tasks, including: Data Collection and Coordination; Establish System Normal Operating Baseline; Establish Target Monitoring Levels; Establish Action Level Values; Establish Corrective Actions; TCEQ Coordination; and On-Call Engineering Support for Water Treatment Plant and Distribution System.
- Data Collection and coordination:
Water Quality Sampling – LNV will collect and compile data on the tested water samples.
Nitrification Monitoring Plan Data – LNV will coordinate with water treatment plant staff to collect the most recent monitoring plan, sampling locations, sampling frequencies, as well as equipment and procedures used.
Monitoring Plan and Action Plan Coordination – LNV will review the city's Nitrification Monitoring Plan for sufficiency and make recommendations and modifications.
- Establish System Normal Operating Baseline:
Analyze Water Quality Sampling Data – LNV will analyze water samples to establish averages and may also use statistics to determine probability of exceeding parameters.
Establish Baseline Values – LNV will use the findings of the analysis tasks and establish a typical range of values to be expected in normal operation.
- Establish Target Monitoring Levels:
Comparison of Baseline Values to Industry Standards – LNV will compare city data collected to industry standards and typical values for similar disinfection protocols to determine in baseline values are acceptable for target values.
Target Value Determination – Based on baseline values, industry standards and previous knowledge of the city's operation procedures, LNV will use engineering judgement to establish preliminary target values.
Staff Input – After preliminary target values have been determined, LNV will coordinate with city water treatment staff to gain input and feedback as to whether the target levels are routinely achievable and revise target values as needed.
- Establish Action Level Values:
Establish Abnormal Operating Indicator Values – Based in data collection LNV will establish values indicative of abnormal or less than optimal operating conditions.
Comparison of Abnormal Indicator Values to Industry Standards – LNV will compare standards and baselines to identify current MCL's.
Action Level Value Determination – Based in baselines, target Values, industry standards and city water treatment operations, LNV will establish preliminary values.
Staff Input – After Preliminary Action Level Values have been determined, LNV will meet with water treatment staff again to determine if Action Level Values are routinely exceeded and revise target values as appropriate.
- Establish Corrective Actions:
Existing system Review – LNV will review the existing system components and determine the current state of the system and identify recent modifications.
Establish Corrective Actions – LNV will use known nitrification processes, physical characteristics of the existing system, known operating procedures and already-established water quality values to recommend preliminary corrective actions for each action level.
Staff Input – After preliminary corrective actions have been determined, LNV will meet with staff once again to determine if corrective actions are feasible and executable. LNV will also ask for suggestions for additional or alternate corrective actions that address specific operational difficulties and are more suited to staff capabilities, then make revisions as needed and incorporate them into the final NAP.
- TCEQ Coordination:
NAP Submittal, Revision and Approval – LNV will submit the NAP to TCEQ for review and approval, respond to any review comments, revise the NAP as needed, then resubmit for further review.
CT Study Submittal, Revision and Approval – LNV will submit the CT Study to TCEQ for review and approval, respond to any review comments, revise the CT Study as needed, then resubmit for further review
Request For Alternate Combined Filter Effluent (CFE) Monitoring Location Submittal, Revision and Approval – LNV will submit the request for approval on an alternate CFE monitoring location. Then respond, revise, resubmit as required, while compiling requested documentation.
- On-Call Engineering Support for Water Treatment Plant and Distribution System:
After going through the process LNV will be the city's go-to support for troubleshooting any issues that may arise during nitrification monitoring, including: revising corrective actions, determining effectiveness of corrective actions. LNV may also provide On-Call Engineering Support to trouble miscellaneous items in the plant or distribution system, such as: pumps, filters, blowers, chemical feed equipment and standpipes.
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