NC0089109_Response to Notice_20221208

To: Landon Davidson, NCDEQ Asheville Regional Office
Daniel Boss, NCDEQ Asheville Regional Office

From: Jan Nedbal

Date: December 8, 2022

Subject: Befesa (AZP) July 2022 WET Test Failure Investigation

Following the July 2022 WET test failure of plant effluent, an investigation was initiated to determine the root cause of the toxicity. This memo is a summary of steps taken to date,
findings from the investigation, and additional actions pending.

After consulting with Robert Kelley of ETT Environmental, the laboratory that conducts the WET testing on our effluent, it was decided to have ETT perform a partial Toxicity Identification
Evaluation (TIE) on the following three samples:

The original effluent samples that failed the WET testing in early July,
A fresh sample of effluent from the FB-306 tank, the primary source of our effluent discharge, sampled on July 29, and
A fresh sample of effluent from the effluent pond (FA-300), the other source of occasional effluent discharge, also sampled on July 29.

Results of Initial TIE Work
The TIE works to identify the type of toxicant present. First, a baseline chronic multi-concentration toxicity test is performed on each effluent sample. Then the samples undergo three
separate treatments:

EDTA chelation, which removes cationic metals,
C-18 Solid Phase Extraction, which removes organics, and
Graduated pH adjustment, which can identify the presence of ammonia and certain metals.

The relative effectiveness of each treatment, compared to untreated effluent, provides information regarding the identity of the toxicant.

The original effluent samples, which exhibited only slight chronic toxicity in the test failure of early July, were found to no longer be toxic during the baseline TIE test performed
in early August. This suggests the toxicant was volatile or degrades over time.

The sample from FB-306 was found to be non-toxic during baseline testing. The sample from FA-300 was found to be toxic at concentrations of 0.9% or higher. For reference, our state-required
WET testing is performed at a concentration of 0.9%.

The subsequent treatments on the toxic FA-300 sample showed that toxicity was not caused by a metal but was caused by some type of organic. The treatments also demonstrated a slight
reduction in toxicity of the effluent sample over time, indicating volatility or degradation of the organic toxicant, consistent with findings from testing of the original effluent
samples that failed the July WET test.

Determining the Type of Organic Present
The FA-300 sample that exhibited toxicity was sent to Rogers & Callcott Environmental in Greenville, SC for volatile and semi-volatile organics testing. Results from this testing are
expected by the end of October.

Additional TIE Testing
A second sample from FA-300 was taken on September 6 and sent to ETT Environmental for additional TIE testing. The results of this testing demonstrated that FA-300 still exhibited some
toxicity, but that it had diminished significantly since the July 29 sampling. The sample was only toxic at concentrations of 5.0% and higher. An organic compound was again determined
to be the cause of the toxicity.

August and September State-Mandated Additional WET Tests
As required, additional effluent WET testing on plant effluent was conducted in August and September, which passed each time.

Conclusions
The original WET test failure in July appears to be the result of discharging effluent from the FA-300 effluent pond, which contained an organic compound that was volatile or degraded
over time. Bromoform was found to be the organic, which is believed to originate from a degreaser that was used onsite.
The primary discharge source, the FB-306 effluent tank, has been demonstrated to be free of toxicity. The toxicity of the secondary discharge source, the FA-300 pond, has been demonstrated
to no longer be toxic at concentrations lower than 5.0%.