How long must monthly monitoring data be kept on file?

Monthly monitoring data must be retained for a minimum of three years. This retention period is aligned with the regulatory requirements that aim to ensure compliance and facilitate monitoring of underground storage tank (UST) systems. Keeping this data on file allows operators and inspectors to maintain a historical record of any monitoring activities, which is critical for identifying patterns, troubleshooting issues, or addressing any incidents of non-compliance.

The three-year timeframe provides an adequate window for reviewing the performance and integrity of the UST system while also striking a balance between record-keeping and the administrative burden on operators. Retaining data for shorter or longer periods may not adequately meet the regulatory standards or the needs for effective monitoring, potentially impacting the environmental safety and operational efficiency of UST systems.