Monitoring

Monitoring can include everything from continuous emission monitoring (CEM) to keeping records of complaints received. Monitoring can be quite expensive. Even if the equipment used for monitoring is not expensive, there is always a frequency of monitoring that must be met, and doing the monitoring takes staff resources that, for a large facility, can be substantial.

One of the most promising emission monitoring techniques recently developed is called parametric emission monitoring system (PEMS). PEMS uses a multivarient computer code to correlate data from parametric monitors on an emission source with measurements from a portable leased CEM system. During initial installation, information from all available parametric monitors is provided to the computer. The PEMS code then evaluates which of the parameters are independent and identifies those parameters. Long‐term monitoring is then limited to the independent parameters. The PEMS code then correlates parameter changes with emission changes – following testing in which the PEMS predicted emissions are compared to CEM data, the CEM system is removed, and PEMS provides emission estimates. Since parametric monitors such as fuel flow and temperature are usually much more reliable than CEM monitors, the availability of the PEMS is usually much higher than that of a CEM system. Operating costs also are lower, because daily calibrations and other CEM maintenance requirements are not necessary.

Opacity Monitoring

Opacity compliance must be addressed in virtually every Title V permit. Opacity limits are found both in agency prohibitionary rules, in NSPS, and in conditions for individual pieces of equipment. Several levels of opacity measurement can be considered, including the following:

• Continuous opacity monitoring systems (COMS)
• EPA Method 9 opacity monitoring
• EPA Method 22 opacity monitoring
• Complaint reporting and response

1. Continuous opacity monitoring systems. COMS are optical monitors at the top of a stack or vent that measure the attenuation of a light beam through stack gases. They provide a continuous reading of opacity that is recorded electronically. Although reliable, they require periodic cleaning of the optical elements to ensure that readings are of gas opacity and not extraneous contamination. Also, they are generally not able to distinguish between PM and water vapor. Opacity due to water vapor is not considered a violation, so this equipment limitation can be important. One technique for distinguishing between PM opacity and water vapor is to install the opacity monitor at a point in the stack where the temperature is above the condensation temperature of any moisture.
2. EPA Method 9 opacity monitoring. EPA Method 9 monitoring is visual monitoring of emissions from a point source by a qualified observer or “smoke reader”: The certification is a course and examination offered by agencies or commercial schools, and to remain certified, a person must be recertified every six months. Monitoring consists of 24 observations of 15 seconds duration and comparison of the opacity of the emissions to a standard gray scale. It is considered a violation if average opacity of the 24 measurements exceeds the standard.For Method 9 to be used as a compliance demonstration, a facility must have a certified “smoke reader” available, and readings must be taken at intervals specified in permit conditions. Typically two employees are certified so that readings can be taken even when one of the certified persons is unavailable. One cement kiln that utilized Method 9 for demonstrating opacity compliance had 18 certified smoke readers on staff to ensure that readings were possible at any time during the 24‐hour operation of the kiln. Notwithstanding, certified readings can only be taken during daylight hours when there is no precipitation (40 CFR Part 60).Only COMS and Method 9 observations can be used to quantify opacity for comparison with a specified standard. The additional methods described below are qualitative.
3. EPA Method 22 opacity monitoring. EPA Method 22 is also a visual observation method, but it does not require a certified smoke reader. Method 22 suggests that observers be familiar with the techniques in Method 9, but asks only that an observer note the percentage of time visible opacity from emissions is observed during the observation period. The observation period must be at least six minutes in duration. The visible opacity must be sustained for the period specified in the applicable regulation to constitute a notable incident, and the requirement is that these incidents be documented, responded to, and reported (40 CFR Part 60, USEPA 1992). An alternate to Method 9 is also available using laser radar (LIDAR 1980).
4. Complaint reporting and response. The simplest method of opacity monitoring is to make a commitment to keep records of any opacity complaints received by a facility and to respond to those complaints with corrective action to eliminate observed opacity. Documentation of the corrective action taken must also be maintained. The record of complaints and corrective action is then provided to the agency as part of periodic reporting.

One method commonly used to check opacity is a combination of Method 22 and the complaint recording and response. The plant manager or other staff regularly drives around the plant to see if there are any visible emissions. For a continuously operated plant, one plant manager conducts this inspection upon arrival at the plant each day.

Record Keeping

Record keeping must be used to provide documentation of monitoring that has been conducted. For material balance compliance demonstrations, record keeping of material used and the composition of the material is the essence of the demonstration. For methods that use a surrogate parameter, or activity data, along with an emission factor to demonstrate compliance, records must be kept of the activity, such as fuel use or operating hours.

A standard condition for both construction and Title V permits is that permitting agency staff or their representatives have authority to enter the premises of the facility at “any reasonable time,” and without prior notification, to inspect both monitoring methods and the records that demonstrate compliance.

Records need not be hard copy. Magnetic or other electronic recording is acceptable provided it can be displayed and audited. In some instances, agencies have required that data be available electronically from agency offices, so that compliance can be verified at any time. Although this requirement is unusual, it is well within the state of the art of current monitoring and data transfer systems.

The discipline of good record keeping is essential to demonstrating compliance with a Title V permit. Use of ditto marks or photocopying of record‐keeping pages in a log indicate poor record‐keeping discipline, and often are indicators of record‐keeping errors. One advantage of electronic record keeping is that repeated records can be copied, and then appropriate changes made to update the inputs.

Periodic checking of records by a person unfamiliar with the operation can quickly identify entries that are understandable only to the equipment operator or person making record‐keeping entries. The records, including the signature or initials of the person making the entries, must be understandable to others.

Reporting

For Title V permit holders, periodic reports must be provided on the results of compliance monitoring. Reporting for Title V permits is required either every six months or annually. Reports are public records and can result in enforcement actions if noncompliance is reported.

Good Conduct Provisions

For any compliance monitoring that is included in a Title V permit, a good conduct provision should be considered. Such provisions have been included in NSPS. They specify that initially periodic monitoring be done frequently; if no noncompliance is monitored, the frequency of monitoring decreases. Several steps of decreases can be included, and if during any monitoring subsequent to the decrease in frequency noncompliance is observed, the monitoring steps back to a more frequent interval and begins the process again. This good‐conduct provision provides an incentive for the facility to stay in compliance, thereby limiting the expense of periodic monitoring.