Residual Risk: NESHAP for Petroleum Refineries
Updated: Aug 29
In 1995 the Petroleum Refinery National Emissions Standards for Hazardous Air Pollutants (NESHAP) was finalized. EPA has been evaluating the risk remaining after this date and has issued a proposed regulation on September 4th, 2007 to address this residual risk. EPA has focused on 3 of the 7 sources of air emissions at refineries: wastewater treatment systems, storage systems and cooling towers.
For each of these emission sources, there are two options on the table. EPA will choose the final option based on their consideration of the relative risk reduction and cost of the options.
Below are the options being considered:
1. Wastewater Treatment Systems – Enhanced biodegradation Units (EBU) a. Option 1: No revisions b. Option 2: Add performance standard and monitoring requirements for EBUs. This includes conducting Appendix C performance demonstrations (90% treatment efficiency for Benzene) which would in turn establish a range of operating parameters where the removal efficiency can be achieved. These parameters (Mixed Liquor Volatile Suspended Solids and the food to microorganism ratio) would then be monitored weekly to demonstrate they are within range.
2. Storage Vessels a. Option 1: No revisions b. Option 2: Remove exemption for slotted guide polls. Facilities who use storage vessels with external floating roofs would need to create a barrier between the liquid surface and the atmosphere for each slotted guide pole. This could be a gasketed sliding cover, or flexible fabric sleeve seal and a gasketed cover or another similar device.
3. Cooling Towers: The existing regulation does not address Hazardous Air Pollutants (HAP) emissions from cooling towers. EPA is proposing two options to monitor for leaks of HAPs into cooling tower systems. These regulations would focus on heat exchangers “in organic HAP service” (lines containing or contacting fluids with at least 5%wt of HAPs). EPA has established similar requirements in other Maximum Achievable Control Technology (MACT) regulations. A very specific definition of leak has been proposed as well as a schedule for repair when leaks are found. The options for identifying leaks into cooling tower water are: a. Option 1: Existing sources would monitor surrogate indicators, such as chemical addition rates, to identify potential leaks of organic HAPs into cooling water. New sources would be required to conduct quarterly sampling. Corrective action would be required if leaks are identified. b. Option 2: Both new and existing sources would be required to conduct monthly sampling of cooling tower water to identify and repair leaks of organic HAPs into cooling tower water.
Number 44 part 3