Initial Safety Consideration and Assessment Report: WWTP Design

This report focuses on the initial safety considerations and assessments for a wastewater treatment plant (WWTP) design. It begins by outlining safety, health, and environmental (SHE) considerations, emphasizing the identification of hazards and risks to workers and the environment. The report then delves into COSHH (Control of Substances Hazardous to Health) assessments and HAZID (Hazard Identification) studies, detailing their roles in identifying and mitigating potential risks. The Dow fire and explosion index is also discussed as a method for ranking risks related to fire and explosion. Mitigation strategies are presented, including the use of PPE (Personal Protective Equipment), gas detection systems, and recommended vaccinations. The report also covers staff training, safety signs, and emergency procedures, including evacuation plans. References to relevant literature are included. The report emphasizes the importance of a comprehensive safety plan to protect personnel and the environment within a wastewater treatment facility.

Running head: Initial Safety Consideration and Assessment
4.0 Initial Safety Consideration and Assessment

1Initial Safety Consideration and Assessment
4.1 Safety, Health, and Environmental Consideration
The safety, health, and environmental (EHS or SHE or HSE) impacts can be known as
systematic process procedure or tools that are used to identify the process impact on the health
and safety of workers as well as the environmental impact of the process (Koller et al., 2000).
The aim of this section is to investigate and identify the hazards and risks from substances and
equipment on workers and the environment. It can be performed through COSHH assessment,
HAZID study, and risk assessment for the wastewater treatment plant (WWTP), where the
purpose of HSE study is to mitigate any risk or hazard to protect the human, animals, and
environment.
4.2 COSHH Assessment and Environmental Impact
The COSHH assessment is concerned about identifying the hazards and risks from
substances that generated or used during the treatment of wastewater for human and environment
(Koller et al., 2000). The COSHH assessment is identified in Appendix 6.
4.3 Process Safety Study (HAZID)
Hazard identification (HAZID) study is an effective and professional tool to define,
assess, and mitigate the potential risk and hazard by providing recommendations. The assessment
of any hazard event is based on provided risk matrix (see Appendix 6) in terms of Severity (S),
likelihood (L), and risk rating (RR) (Koller et al., 2000). In addition, the expander, application,
and explanation of HAZID guide work can be shown in Appendix 6. The (HAZID) study of the
wastewater treatment can be presented also in Appendix 6.
4.4 DOW fire and explosion
DOW fire and explosion is a method developed by the Dow Chemical Company that can
be used for ranking the risk related to fire and explosion within a particular process. The analysts
are responsible for calculating the hazards and the explosion index with the use of material
characteristics and process data (Nezamodini, Rezvani & Kian, 2017). It is one of the popular
safety measure methods that has been designed to support in quantifying the risk or expected
damage from the potential for or explosion events in the real-time by the users and identification
of equipment that help in escalating the incident and communicating the fire and explosion risk
potential to the management of the Safety team.
4.5 Mitigating Strategy
Wastewater Treatment plants produce or require the use of toxic and/or combustible
substances. Chlorine and ammonia are commonly used substances to treat the Hydrogen Sulfide
(H2S). H2S is a deadly toxic gas, which is present in untreated wastewater that contains raw
sewage and also can be generated as a byproduct of sludge treatment processes. Methane gas is
produced as a byproduct of raw sewage and sludge digestion. Parts Per Million (ppm) monitors

2Initial Safety Consideration and Assessment
are typically used to alert workers and safety personnel if these toxic gases reach ppm levels
above the safe exposure levels as shown in Table 8.
Fire detections system consists of smoke detecting elements that are scattered all over the
plant, especially near the equipment that have a higher possibility of a fire breakout (e.g.
Digester, Biogas Holder and Thermal Hydrolysis reactor). If the smoke detectors detect smoke, a
loud fire alarm will be triggered notifying the workers to evacuate the plant and meet at the
proper assembly point as shown in the plant layout.
Wastewater treatment plants are designed to treat all municipal waste, the process of
waste treatment results in the byproduct of combustible and toxic gases. Toxic and combustible
gases that are produced on cite can accumulate in working areas or confined spaces, decreasing
oxygen amounts and making those areas extremely dangerous, these areas must be monitored on
a continuous basis to protect both personnel and the plant. Hazardous Gases that are found in the
plant can be shown in Table 8:
Table 1: Combustible and toxic gases that are found in the wastewater treatment plant
Combustible Gases Maximum Safe
Limit
Toxic Gases Maximum Safe limit
Methane (CH4) 1 ppm Hydrogen Sulfide
(H2S)
5 ppm
Pentane (C5H12) 120 ppm Carbon Monoxide
(CO2)
20 ppm
Hydrogen (H2) 100 ppm
A gas detection system is used in the wastewater treatment plant to monitor the whole
plant and detect any dangerous gases that are present to prevent the breakout of a fire or causing
harm to the workers. The wastewater treatment plant is fitted with a Fixed Gas Detection alarm
system, this system is integrated in the Building management system. Gas detection elements are
scattered all over the plant especially in working areas and confined spaces, these elements are
wired to a main screen in the control room. The main screen shows the levels of oxygen and if
there are any toxic gases present. If there are dangerous, gases present over the safe limit (see
table 8), an alarm will be triggered and the workers will evacuate the plant.
#.# Personal Protective Equipment
#.# General PPE
The workers on the site of a wastewater treatment need to consider wearing personal
protective equipment (PPE). The employees on the wastewater treatment site need to be aware
about how important the PPE is for them and how important it is to be safe on the site. The
workers need to be trained on how to use the PPE the right way and to make sure hands are
washed immediately with soap and water after removing the PPE.

3Initial Safety Consideration and Assessment
The most recommended PPE on wastewater treatment plants are goggles, protective face
masks, liquid- repellent coveralls, water proof gloves and rubber boots. All these recommended
PPE measures need to be worn by all the workers all together as each of them has a duty to
prevent sewage contact as it is shown in table 9 (Centers for Disease Control and Prevention,
2015).
Table 2: Table showing the purpose of PPE in industry (Centres for disease, control and prevention, 2015)
PPE Purpose
Goggles Protecting the workers eyes from any sewage
materials to the eyes.
Protective face shield To protect the workers from the sewage, by
covering the face which covers the nose and the
mouth.
Liquid- repellent coveralls To protect the whole body of the workers
including the clothes, except the face from the
sewage contact.
Water proof gloves To protect the employees hands from sewage.
Rubber boots To prevent the workers feet from sewage.
#.# Portable gas detectors
They are a handheld device that a worker must carry with him in the plant at all times. It
measures the air quality and it detects any hazardous gases that can be life threatening. When a
hazardous gas is detected the device beeps to notify the worker that there is a hazardous gas
present. If the device beeps the worker should leave the area immediately.
#.# Recommended Vaccinations for workers:
The recommended vaccinations for sewage or human waste workers must be created in
consultation with the health authorities. Tetanus vaccinations are important and should be up to
date. Moreover, vaccinations for Typhoid fever, Hepatitis A & B, and Polio must also be
considered. However, the health and safety risks of the workers varies among different locations.
So, it is best to consult a local health and safety expert to give a specific health and safety plans
(Centers for Disease Control and Prevention, 2015).
#.# Staff Training
Safety training involves providing instructions to the workers in relation to the risks and
dangers associated with the wastewater treatment plant in South Wales. The Occupational Safety
and Health Administration (OSHA) need to be taken into consideration while providing the
training and health risks related to toxic gases such as hydrogen sulphide and methane that need
to be provided as these gases are present in the plant (Michaels, 2016). The safety issues related
to monitored and evaluated by the worker on a regular basis, thus, risk monitoring and evaluation
training need to be provided to the employees prior to commencement of the project that will help
in mitigating risks and hazards.

4Initial Safety Consideration and Assessment
#.# Safety Signs
Safety signs and symbols are the basic requirements of the Safety Assessment program
that include placing safety signs in the wastewater plant for easy identification and warning to the
workers that are exposed to hazards in the plant. These assist in effective communication of the
vital instructions and reinforcing the safety message that needs to have adhered in case of
emergencies. Training to the workers about the signs and symbols of safety need to be given on a
priority basis that will help to mitigate any risk or hazards that are prone to occur in such a
hazardous workplace.
#.# Emergency procedures
An emergency procedure should be implemented in order to effectively manage the
adverse event that may occur in order to prevent or minimize environmental damage or damage
to human lives. It involves the documentation of a systematic process that involves response and
recovery from any harmful events that are related to the emergency. The capability of the
wastewater facility staff to respond to an emergency rapidly will help in the prevention of any
unnecessary complication and, thus, help in protecting the health and safety aspect. Thus,
communication of the response to each employee is crucial in this case.
#.# Evacuation plan
The wastewater plant is an unpredictable workplace that may pose a risk at any time
without any signs or signals; therefore, it is important to have an evacuation plan that will help in
the systematic and comprehension exit of all the staff in the plant in a smooth and quick manner.
Special training will be given to all the employees irrespective of their function about this plan
and all safety measures need to have adhered during the plan in order to maximise the response.

5Initial Safety Consideration and Assessment
References
Michaels, D. D. (2016). RE: Occupational Safety and Health Administration (OSHA) Draft
Weight of Evidence Guidance Document (OSHA-2016-0004).
Nezamodini, Z. S., Rezvani, Z., & Kian, K. (2017). Dow’s fire and explosion index: a case-study
in the process unit of an oil extraction factory. Electronic physician, 9(2), 3878.