Available Now: 2023 Schedule of Hazmat & RCRA Training

Question of the Week: Using a Mass Balance Approach for RCRA Tanks

Posted on 5/24/2011 by James Griffin

Q. Does a hazardous waste storage tank need to be emptied every 90 days (or 180 days), or can a ”mass balance approach” be taken?
A. EPA stated in the January 11, 1982 issue of the Federal Register (47 FR 1250) that generators must remove all wastes from the tank within 90 days from the time he first places waste in the “empty” tank. The discussion goes on to say that the tank is considered empty “when its contents have been drained to the fullest extent possible…but it is not expected that 100% of the wastes will always be removed.” 
The EPA recognized that tank systems do not always allow for complete drainage due to flanges, screens, or siphons. Therefore, as general guidance, the EPA stated that a tank is considered empty when “the generator has left the tank’s drainage system open until a steady, continuous flow has ceased.”
In October 12, 2006, the EPA was asked whether a “mass balance approach” was acceptable in proving that no waste was accumulated in a storage tank for more than the applicable time limit. In their answer, the EPA stated that their interpretation of 40 CFR 262.34(a)(1)(ii) does allow for this mass balance approach. 
The conclusion is that tanks can be operated in one of two ways: in a “batch process or in a continuous flow process.”
The batch process refers to when a tank would receive a “batch” of hazardous waste, or subsequent batches, and the tank is fully emptied within 90 days from the date the first drop of hazardous waste was placed in the tank. 
The continuous flow process is when a tank receives hazardous waste on an ongoing basis. In this scenario, the EPA discusses a “mass balance approach.” The “key parameters” for this approach take into account things such as: the daily throughput of hazardous waste, the time period the waste resides, and the volume of the tank. 
The EPA considered that under a continuous flow process where periodically emptying the tank is impractical, a generator could comply with the 90-day accumulation limit by measuring the volume of hazardous waste that flows into and out of the tank and showing that an amount of hazardous waste at least equal to the volume of the tank flows through during each 90-day period. This is called a“mass balance approach.”
Another important thing to note is that it is the generator’s responsibility to prove the continuous flow process does not allow waste to accumulate more than 90- (or 180-) days and meets all the requirements applicable to the tank. The EPA discusses examples of ways to prove this, such using equipment to monitor material entering and leaving the tank and recording the results. 

Tags: hazardous, RCRA, waste

Find a Post

Compliance Archives

Lion - Quotes

The instructor took a rather drab set of topics and brought them to life with realistic real-life examples.

Tom Berndt

HSE Coordinator

I can't say enough how pleased I was with this course! Everything finally makes sense.

Kim Graham

Lab Manager

Our instructor was very dynamic and kept everyone's interest. Hazmat shipping can be a dry, complicated topic but I was engaged the entire time.

Kimberly Arnao

Senior Director of EH&S

Lion provided an excellent introduction to environmental regulations, making the transition to a new career as an EHS specialist less daunting of a task. Drinking from a fire hose when the flow of water is lessened, is much more enjoyable!

Stephanie Weathers

SHE Specialist

I really enjoyed this training. Even after years on both sides of the comprehension coin, I find myself still learning! The quality of the delivery exceeded much of the training I have received in the past.

Neil Ozonur

Safety Officer

Lion's online training is more comprehensive, has better slides, and is a superior training experience than what I would get from other trainers.

Robert Brenner

District Environmental Manager

I like the consistency of Lion workshops. The materials are well put together and instructors are top notch!

Kevin Pylka

Permitting, Compliance & Environmental Manager

I used the IT support number available and my issue was resolved within a few minutes. I don't see anything that could have made it better.

Danny Province

EHS Professional

Very well structured, comprehensive, and comparable to live training seminars I've participated in previously. I will recommend the online course to other colleagues with training requirement needs.

Neil Luciano

EHS Manager

The instructor did an excellent job presenting a very dry subject; keeping everyone interested and making it enjoyable.

Marc Bugg

Hazardous Waste Professional

Download Our Latest Whitepaper

This guide will help you identify 25 of the most -cited errors in RCRA training, recordkeeping, hazardous waste ID, container management, universal waste, and laboratories.

Latest Whitepaper

By submitting your phone number, you agree to receive recurring marketing and training text messages. Consent to receive text messages is not required for any purchases. Text STOP at any time to cancel. Message and data rates may apply. View our Terms & Conditions and Privacy Policy.