MEMORANDUM

Date: July 23, 2014

Subject: Report of June 24, 2014 Site Visit to Clean Harbors in Deer Park, Texas

From: Alden West, EC/R Incorporated 

Lesley Stobert, EC/R Incorporated

To: Paula Hirtz, EPA/OAQPS

This memorandum summarizes the visit to the Clean Harbors facility in Deer Park, Texas that 

was conducted on June 24, 2014. The purpose of this visit was to better understand the processes 

used in the Offsite Waste and Recovery Operations (OSWRO) industry, the controls in place to 

reduce hazardous air pollutants (HAP) emissions, and the characteristics of the emission points at

this facility. This information will assist the EPA in the promulgation of amendments to the 

emission standards for the OSWRO industry. 

A background discussion of this project is provided, followed by an overview of the facility, a 

description of the off-site waste operations at the facility, and a summary of emission sources at 

the facility. The final section includes a summary of action items resulting from the meeting with 

Clean Harbors. 

The participants in the site visit included the following:

Ana Woods, Clean Harbors

Paula Hirtz, U.S. EPA/OAQPS

Lesley Stobert, EC/R Incorporated

Alden West, EC/R Incorporated

BACKGROUND

Section 112(d) of the Clean Air Act requires the EPA to develop standards for each major source 

category listed under section 112(c). These technology-based standards are often referred to as 

maximum achievable control technology, or MACT, standards. The National Emissions 

Standards for Hazardous Air Pollutants (NESHAP) for Off-site Waste and Recovery Operations 

(OSWRO) were promulgated on July 1, 1996 (61 FR 34139) and codified at 40 CFR part 63, 

subpart DD. The Clean Harbors facility in Deer Park, TX is subject to subpart DD because it 

receives certain wastes from off-site locations for storage and treatment, recovery or disposal.

Section 112 of the Clean Air Act contains provisions requiring the EPA to periodically revisit the 

technology-based standards. Specifically, section 112(d)(6) states that the EPA shall review 

these standards and revise them “as necessary (taking into account developments in practices, 

processes, and control technologies)” no less frequently than every eight years. The second stage 
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in the review process focuses on reducing any remaining (i.e., “residual”) risk according to CAA 

section 112(f). Section 112(f)(2) directs the EPA to assess the risk remaining (residual risk) after 

the application of MACT standards and promulgate additional standards as necessary to provide 

an ample margin of safety to protect public health, or to prevent, taking into consideration costs, 

energy, safety, and other relevant factors, an adverse environmental impact. On May 30, 2014, 

the EPA proposed amendments to the OSWRO MACT standards to address the results of the 

residual risk and technology review (RTR) conducted under the Clean Air Act.

A site visit of the Clean Harbors facility was conducted to better understand the current 

processes and control technologies in the OSWRO industry before promulgation of final 

amendments to the OSWRO MACT standards. As part of the RTR process, the EPA is seeking

additional information to improve the Agency’s understanding of the OSWRO processes and 

emission points, to improve the data used in site-specific emission profiles and to better 

characterize the maximum risks to surrounding populations as a result of activities at OSWRO 

facilities. Further, the May 30, 2014 proposal includes new provisions that may change the way

certain OSWRO sources are required to operate. This site visit was conducted to better 

understand the technical and operational implications of these changes based on current 

processes observed at the facility and discussions with facility personnel. 

PLANT SITE OVERVIEW

The Clean Harbors facility is located east of Houston in Deer Park, Texas. The facility is 

exclusively operated for the management of offsite-waste by incineration in a kiln. Ancillary

units at the facility include a landfill, a wastewater treatment plant, and storage/processing units. 

Types of wastes managed by the facility include Resource Conservation and Recovery Act 

(RCRA) hazardous waste, polychlorinated biphenyls (PCBs), soils regulated by the Animal and 

Plant Health Inspection Service (APHIS) of the Department of Agriculture, Drug Enforcement 

Administration (DEA)-controlled substances, infection wastes, and non-regulated wastes.

PROCESS DESCRIPTION

As noted above, the processes of interest at this site are those regulated by the OSWRO MACT

standards. The description provided below is a summary developed from materials provided 

during the site visit and from notes taken based on discussions with Clean Harbors personnel. 

When waste is first received at Clean Harbors it goes through a pre-acceptance procedure, 

including a document review and sampling, if required. Ten percent of drums (55 gal) received 

are sampled and most bulk containers are sampled, unless exempted. Examples of sampling 

exemptions include wastes that are extremely toxic or are typical/frequently received. 

Exemptions and other guidance on waste sampling and analysis are outlined in the facility’s 

waste analysis plan (WAP), which is required by RCRA. The constituents of the waste are 

predetermined by the generator and sampling is done to confirm that the specified profile is 

accurate. Characteristics of the waste that are sampled include BTU content, metals, 

polyaromatic hydrocarbons (PAHs), viscosity, water activity and PH. Containers are tracked 

using a unique bar code identifier and by monitoring the weight through each feed port to the 

kilns.
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Typical waste streams received by Clean Harbors include contaminated process wastewaters, 

oils, spent flammable solvents, organic and inorganic laboratory chemicals, paint residues, debris

from toxic or reactive chemical cleanups, off-spec commercial products, cylinders and labpacks. 

Wastes are received in many forms, including solids (in drums, buckets, boxes or containers), 

sludges (in tank trucks, bins, vacuum boxes or drums), liquids (in drums or other containers, tank 

trucks, rail tank cars or bins), and gases (in metal cylinders). Waste is stored and processed in a 

variety of ways depending on its composition and state of matter. In general, bulk containers 

(i.e., roll-off boxes) are stored outside and smaller containers are stored inside. 

Clean Harbors operates several process tanks that consist of steel and/or concrete lined pits or 

tanks used for various waste processing operations, including repackaging of waste, mixing to 

achieve the optimal composition for incineration (e.g., high BTU content wastes mixed with low 

BTU content wastes), and waste feed to the incinerator using a clamshell bucket. Three waste 

mixing pits are located in a building designed as a permanent total enclosure, which is vented to 

an incinerator. 

Clean Harbors operates a tank farm for storage of liquid wastes. Wastes designated for unloading

to a storage tank are first analyzed for compatibility with the existing material in the tank. All 

storage tanks are equipped with fixed roofs and nitrogen blankets to suppress emissions. Vapors

originating from normal pressure fluctuations in the tank are routed through a liquid knock-out 

pot to an incinerator; a carbon bed is also installed for back-up emission control. All storage 

tanks are equipped with rupture discs to relieve emergency pressure buildup and high 

level/overflow alarms to prevent overfilling. Clean Harbors provided a list of all storage and 

process tanks, including tank ID, capacity, dimensions and other information. 

The incineration system consists of two units, Train I and Train II. Train I has a thermal capacity

of 180 MMBtu/hr and consists of a 3.6 meter diameter rotary kiln, a horizontal afterburner, and a 

liquids burner. Train II has thermal capacity of 213.5 MMBtu/hr and consists of a 4.4 meter 

diameter rotary kiln, a rotary reactor, and a vertical afterburner. Diesel fuel, used oil, or natural 

gas is supplemented if there is not adequate BTU content to operate the incinerator. After 

incineration, the exhaust gas flows through a saturator to rapidly cool the gas and minimize 

dioxin formation. Each train is equipped with back-end pollution control systems, including 

packed tower condensers, a venturi scrubber, a wet electrostatic precipitator and a selective 

catalytic reduction system.

Clean Harbors operates an onsite landfill for disposal of residual waste from the incineration 

process. A wastewater treatment plant is also operated to manage aqueous byproducts from backend emission control units, including saturators and scrubbers.

EMISSION SOURCES

Emission sources at Clean Harbors include tanks, containers, fugitives, transfer systems, and 

control devices.

Storage tank emissions can occur from the evaporation of liquid wastes placed in the tank. The 
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storage tanks at Clean Harbors are equipped with fixed roofs and nitrogen blankets to reduce 

evaporation of tank contents to the atmosphere. Tanks are also equipped with vents that provide 

relief from fluctuations in tank pressure resulting from normal operating conditions such as 

filling/emptying and changes in atmospheric temperature. Vapors released by the 

pressure/vacuum valves are routed through a liquid knock-out pot to the secondary combustion 

chamber of one of the hazardous waste incinerators. The incinerator is considered a control 

device under the OSWRO MACT standards. Storage tanks at Clean Harbors are also equipped 

with emergency relief valves that release tank vapors to the atmosphere if excessive pressure or 

vacuum develops. In the event of an emergency, all tank pumps can be shut off from the main 

control room or by a field operator. 

Emissions from containers can occur if the container is leaking or if the cover of a container is 

removed for sampling or other purposes. All containers at the facility, including drums and bulk 

containers, are controlled by a cover and closure device (e.g., a lid on a drum or secured tarp on a 

roll-off box). 

Process tanks are another source of emissions at the Clean Harbors facility. The building 

surrounding the three mixing/material processing pits (T-1001-1, 2 and 3) is designed as a 

permanent total enclosure (PTE). The building is vented to an incinerator, and a carbon bed 

absorption unit serves as a backup air pollution control device if both incinerators are out of 

service. The main doors of the building are opened when necessary to add or remove waste. 

During the site visit, a noticeable odor was observed in this area indicating the presence of 

chemical vapors. There are additional processing pits for operations other than mixing, such as 

receipt of bulk solids and clamshell feed to the incinerator. No emission controls are identified

for these additional pits in the information provided by Clean Harbors. 

Clean Harbors operates numerous valves, pump seals, flanges, open-ended lines, and other 

equipment components that could leak hazardous vapors to the atmosphere. Clean Harbors 

complies with the RCRA air emission standards for equipment leaks (40 CFR part 264 subparts 

BB and CC).

Transfer systems are a potential source of emissions at Clean Harbors and are subject to the 

OSWRO MACT standards. Transfer systems operated at the facility include pumps and 

conveyors. 

As mentioned, Clean Harbors operates a wastewater treatment plant (WWTP) to manage 

aqueous byproducts. The WWTP is not subject to RCRA or OSWRO standards because it 

exclusively treats waste generated onsite. Based on a review of the Title V operating permit for

Clean Harbors, the facility is subject to the process wastewater provisions of the Hazardous 

Organic NESHAP (HON) at 40 CFR part 63 subpart G. 
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ACTION ITEMS

 EPA agreed to resend the ICR to Clean Harbors, including to Ana Woods who is currently 

the environmental coordinator for the site. 

 EPA requested HAP emissions from OSWRO operations at the facility, including the latitude 

and longitude of their operations. Clean Harbors agreed to send this information by the end 

of the public comment period. 

 EPA agreed to send the link to the website for the OSWRO proposal and a link to the site 

where Clean Harbors can access and revise their modeling data.