6.1 Safe Drinking Water Act Compliance: MCLs, Monitoring & Violations

Safe Drinking Water Act Compliance: MCLs, Monitoring & Violations

The ABC Water Treatment outline puts "determine if water quality violations have occurred," "ensure compliance with regulatory agency standards," and "notify the public according to regulatory requirements" in the Security, Safety, and Administrative Procedures area - which carries 14 of 100 items and is 11 of 14 application level. These are not definition questions; they are "here is a situation, what does the rule require" questions.

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1. The Regulatory Structure

Congress passed the Safe Drinking Water Act in 1974, amended significantly in 1986 and 1996. EPA sets National Primary Drinking Water Regulations. Virginia holds primacy, meaning VDH's Office of Drinking Water enforces standards at least as stringent as the federal ones under the Waterworks Regulations, 12VAC5-590.

Two kinds of standards

MCLG versus MCL versus treatment technique

• Maximum Contaminant Level Goal (MCLG) - the level at which no known or anticipated adverse health effect occurs, with a margin of safety. Non-enforceable. MCLGs for known carcinogens and for pathogens are set at zero.
• Maximum Contaminant Level (MCL) - the enforceable standard, set as close to the MCLG as feasible using the best available technology, taking cost into account. This is why the MCLG for lead is zero but the action level is 0.015 mg/L, and why the MCLG for TTHM is not zero for all species but the MCL is 0.080 mg/L.
• Treatment technique (TT) - a required process, used where measuring the contaminant is not economically or technologically feasible. The Surface Water Treatment Rules, the Lead and Copper Rule, and the Revised Total Coliform Rule assessments are all treatment techniques.

Public water system categories

Rule applicability follows the category: TNC systems are subject to the acute contaminants (nitrate, nitrite, coliform) but not to the full chemical suite or the Consumer Confidence Report requirement.

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2. The Rule Families an Operator Must Recognize

Maximum Residual Disinfectant Levels

Often overlooked because they are limits on the disinfectant rather than a contaminant:

Exceeding an MRDL is a violation in the same way as exceeding an MCL.

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3. Monitoring and Compliance Arithmetic

Running annual average (RAA)

Most chemical MCLs are evaluated as the average of the four most recent quarterly samples. A single high quarter does not automatically violate - unless the result is so high that even with three zeros the average would exceed the MCL, in which case the violation is immediate.

Locational running annual average (LRAA)

Stage 2 D/DBPR changed the arithmetic in a way that matters enormously to operators. Under Stage 1, all sample sites were averaged together system-wide, so a low site could offset a high site. Under Stage 2, each monitoring location has its own running annual average, and any single location exceeding the MCL is a violation.

Worked example

A system has four Stage 2 sites. Quarterly TTHM results at Site 3 are 62, 78, 91, and 95 micrograms/L.

• LRAA at Site 3 = (62 + 78 + 91 + 95) / 4 = 81.5 micrograms/L
• MCL = 80 micrograms/L
• Violation at Site 3, regardless of what the other three sites did.

Acute versus non-acute

• Acute MCLs - nitrate (10 mg/L as N), nitrite (1 mg/L as N), total nitrate plus nitrite (10 mg/L), and the E. coli MCL. A single confirmed sample violates, and the notice is Tier 1.
• Non-acute - averaged over time, Tier 2 notice.

Monitoring frequency and reduced monitoring

Frequency depends on the contaminant, the system size, the source type, and the system's history. Reduced monitoring (for example, moving from quarterly to annual, or annual to once per three years) is available for many contaminants after a demonstrated period of results well below the MCL, at the state's discretion. Reduced monitoring is a privilege that a single detection can revoke.

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4. Violation Categories

A monitoring violation is still a violation. It appears on the CCR, it appears in the state's enforcement data, and repeated monitoring violations are among the most common reasons small systems end up under a consent order. The sample that was never taken is a certain violation; the sample that was taken and came back high may not be.

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5. Sanitary Surveys and Significant Deficiencies

A sanitary survey is an on-site review by VDH of the system's capability to deliver safe water. Frequency is generally every 3 years for community systems and every 5 years for non-community systems, with shorter intervals for systems with a history of problems and longer intervals available for outstanding performers.

The eight elements evaluated

1. Source - protection, construction, and quality
2. Treatment
3. Distribution system
4. Finished water storage
5. Pumps, pump facilities, and controls
6. Monitoring, reporting, and data verification
7. Water system management and operations
8. Operator compliance with state requirements

Note element 8: the operator's own license status and compliance are a survey element. A classified waterworks operating without a properly licensed operator is a survey finding.

Significant deficiencies

A significant deficiency is a defect in design, operation, maintenance, or a failure or malfunction of a source, treatment, storage, or distribution component that the state determines to be causing, or has the potential to cause, the introduction of contamination. Common examples at Virginia systems: unscreened or damaged storage tank vents, an overflow pipe without an air gap, an unsealed well casing or missing sanitary seal, a cross-connection, inadequate disinfection contact time, and unsecured facilities.

When a significant deficiency is identified, the system must consult with the state within 30 days and complete corrective action or be on a state-approved corrective action schedule. Failing to correct is a treatment technique violation under the Ground Water Rule and triggers public notification.

Preparing for a survey

Have ready: the current operating permit, plant records and monthly operating reports for the review period, laboratory reports, the sample siting plan, the cross-connection control program records, the emergency response plan, tank inspection reports, calibration records, valve exercising and flushing records, the service line inventory, operator licenses and CPE documentation, and the corrective action status of any prior findings. A survey goes badly not because the plant is bad but because the records cannot be produced.