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Health And Safety Hazards For Sewage Treatment Plant Construction Essay

Paper Type: Free Essay Subject: Construction
Wordcount: 3214 words Published: 1st Jan 2015

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All tanks and chambers above the safe flood level and the highest flood level of the nearby rivers/drain and design to what flood return period. There any buried pipelines or cables under buildings within the treatment facility and it is clearly indicated on the layout drawings. The layout of temporary diversion and location of temporary treatment facilities. The location of the screening bins is a far from process plant but easily accessible and the basis of sizing the bins area is lorry loading? There are lifting devices provided and they are vehicle working load and they are found in open air before the uv process and can lift about 1500kg.

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1.2 Access Road

The facility is located not near to a public road to allow immediate access to the plant/facility The ingress and egress routes to and from the plant are suitable for desludging tankers The entrance and exit gate is not nearby the public road .Road access should be provided adjacent to the equipment or crane extended to the nearest road. If fixed crane beam extends over the road, there is the minimum vertical clearance shall be 5.5m. Adequate signage provided. Head clearance for tanker trucks entering the gate provided and the clearance height is none as there is no obstruction. Sufficient turning radius on the roads to enable access and maneuverability for tankers and heavy vehicles. Location of sludge desludging area is suitable for tankers to access and empty the sludge into the chamber.

1.3 Handrails/Guardrails and Access Ladders

Safety handrails or grating been installed at walkways and around open holes at the plant. Toe plates and kick plates shall be fitted along the outer edges of all walkways or ladders and shall be part of the structure and not the floor panels. Toe plates shall extends 100mm above the top level of the floor panels. Floor panels shall be sized so that each panel does not weight more than 50 kg. Hand railing provided at all places where there is potential of falling around al tanks and other places where falling height is greater than 1.5m. Staircases provided where height is greater than 300 mm. Fixed ladder to access working areas for purposes of servicing, maintenance or normal operation works.

1.4 Precaution Against Damp

All wall mounted equipment is fitted with spacers to provide minimum gap of 5 mm. All holes in equipment is sealed against the ingress of water. Any items exposed to weather or water shall be free of water traps and drain holes shall be provided where necessary. Electrical equipment which is not sealed against free movement of air is protected from condensation with anti-condensation heaters and thermostatically controlled.

1.5 Substation / Electricity Meter/ Lamp Post

Location of electricity meter or the substation. There is adequate street lighting provided around the plant and the number of lamp post provided is 2 .All buildings and major process units at the treatment facility are lighted adequately.

1.6 Buffer Zone

The following buffer zone requirements satisfied? 30 m minimum from fence to nearest habitable building property line within residential and commercial development 20 m minimum from the fence of treatment plant to the nearest property line within industrial development 10 m minimum from the fence of the treatment plant to the nearest habitable building property line if the proposed treatment plant is fully enclosed.

1.7 Effluent Discharge Point

Where is the location of effluent discharge point for the facility and is it clearly indicated on the layout drawings with relation to existing receiving water bodies.

1.8 Water Supply

If tankers and desludging activities take place, there is provision for stand pipes for cleaning purposes. the stand pipe is located and location for toilets for operators to change and clean themselves after work is found within the same building at the reception, near the laboratory room.

2.0 Screen Chamber (Fine And Coarse Screens)

2.1 Bar Screens

Dewatering or perforated plate or trough, provided for ease of maintenance of the screens

2.2 Mechanically Raked Screens

Automatic conveyor to transfer screenings to skips. Screen motor located above the high water level and access provided for maintenance. Provision of explosion proof floodlights. Provision of emergency stop button at a convenient and visible location .A working platform for ease of operations and maintenance. Provision of hand rail or guard (Refer to item 1.3) .Location of screening bins must be near the screen area. Bins provided should have adequate capacity and must be equipped with leachate collection tray and covers to prevent odour release. Bins should be provided with rollers.

2.3 General

Provision of staircase access with sufficient width (Refer to item 1.3) .All screen chamber sumps to be fully open at the top for good ventilation. Inlet penstock provided to isolate the inlet works for maintenance purposes. All drive units shall be weatherproof

3.0 Pump Sump

Emergency overflow pipe to by-pass the influent sewage during power failure (away from residents) and location of overflow pipe discharge. Provision of crane for maintenance purposes .Sufficient access to the pump station either from the top surface or via entry from the screen chamber .Is dry well provided with force ventilation and air outlet shall be located adjacent to pump motors to assist cooling .Lighting systems shall be interconnected with ventilation .Provision of handrails and MS grating (Refer to item 1.3). If the valve chamber is located in the sump, the opening of the valve chamber shall be enclosed with MS grating .Provision of working space or platform for ease of operation in both wet well and valve chamber .Dry well adequately lit and it should be weather proof, vapour proof and explosion proof. Miscellaneous Issue

4.0 Grit Chamber

Provision of working platform along the grit channel. Provision of handrails or guardrail at exposed sumps or elevated working areas (Refer to item 1.3). Provision of grit storage bin or skip with rollers, perforated tray and covers . Easy access to the grit removal facility by dump trucks and sufficient maneuver space (Refer item 1.2). To provide a chute to remove the grit into the skips. To provide sufficiently big grit chamber for ease of maintenance. To provide a drain pipe to drain water into the pump sump to avoid ponding. Provide steps into the chamber (pump). Misc Issues

5.0 Grease Chamber

Provision of working platform along the grease chamber .Provision of hopper to collect scum and grease. Provision of handrails or guardrail at exposed sumps or elevated working areas. (Refer to item 1.3) Provision of grease storage tank with rollers and with drain pipes and valves at the bottom of the tank for removal of settled solids .Easy access to the grease removal facility by dump trucks and sufficient maneuver space. (Refer to item 1.2) .Staircases must not be beneath the walkway (staircase need to be away from walkway) Miscellaneous Issue

6.0 Blower Room/Control Panel Or Room

Provision of acoustic enclosures for blowers including acoustic door .Provision of exhaust fan with silencer to circulate air around the blower room. Toilet facilities to be isolated from the blower room due to heat and noise hazards. Provision of lifting davit for maintenance of the blowers. Provision of rotating strobe light at the control room to indicate malfunction of blower or other equipment.Provision of adequate space for blower removal or installation during maintenance. Water storage tank to be located in such a way that water will not splash on the control panels. Control panels in the Blower/Control Panel room is to be isolated from the blower room .Allow at least 900 mm access space even when cabinet doors and the like are open. Miscellaneous Issue

7.0 Balancing Tanks

Sufficient walking or working space along the tanks .Provision of handrails or guards if the tanks are elevated. (Refer to item 1.1 on handrail and guard rail)Miscellaneous Issue

8.0 Primary / Secondary Clarifier

9.0 Biological Treatment System

10.0 Sludge Thickener

Provision of adequate walking or working space .Provision of potable/clean water for regular cleaning of the overflow weir .Provision of force main type of pipe from the thickener to the sludge holding tank .Desludging pipe provided to be situated above ground All sludge holding tanks to be on sloped flooring

11.0 Sludge Holding Tank .

Adequate access for desludging tanker. (Refer to item 1.2 on access road) Provision of desludging pipe (if the sludge holding tank is elevated) appropriately positioned. Sufficient walking or working space along the sludge holding tank. (Refer to item 1.3). Provision of handrails or guards if the sludge holding tank is elevated. (Refer to item 1.1 on handrail and guard rail) .Provision of desludging pipe either by force main or gravity flow. All sludge holding tanks to have isolating facilities. Each sludge holding tank to have separate feeding pipes with individual isolating valves. The top level of holding tanks to be approximately 6 inches above ground should the tank be below ground level. Overflow pipe from sludge holding tank to the aeration tank to be of sufficient diameter to prevent possibility of the pipe choking.

Miscellaneous Issues

The key components of the wastewater-treatment plant each play an important role in the treatment process. The bar screens, primary and secondary clarifiers, aeration basins, and disinfection and effluent pumping station all must be in proper working order. Damage to any one of these components could result in inadequately treated wastewater. Wastewater-treatment facilities plan for natural disasters, but protecting the plant from attack has not been a high priority. Many facilities now are considering ways to improve their security. Experts have identified the headworks, where the wastewater first enters through the collection system, as particularly vulnerable to attack. Restricting or blocking the flow of the wastewater into the facility could cause backups throughout the collection system, creating a public health hazard.

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In St Martin, the wastewater facility access road connecting it to a main highway. There is the concerned that access to and within the treatment plant could be blocked by hurricane or storm-tide conditions. There is a guard at the main entrance. Nonetheless, the property is still vulnerable to acts of nature and terrorism. The impediment of movement to and from St Martin’s property would cause major problems with both response and evacuation.

The sewage system uses pumping stations when gravity is insufficient to move waste. One expert explained in the Andress report, “One pumping station has the capacity to pump 25 thoun gallons of wastewater per day.” Another expert added that, “Destroying or disabling a pumping station could cause the collection system to overflow raw sewage into the streets, and into surface waters, and back up sewage into homes and businesses…. The remoteness and geographic distribution of pumping stations, and their lack of continuous surveillance, make them particularly vulnerable.”

With approximately 60 miles of sewer pipes and more than 2 pumping stations, St Martin vulnerabilities are spread throughout 14 municipalities. An overflow of raw sewage could threaten the health of humans, wildlife and the environment of Southern St Martin.

According to GAO, wastewater facilities increasingly are using control systems, such as the Supervisory Control and Data Acquisition network. These systems monitor and control operations from a central location. Misuse of the SCADA could cause too-high or too-low levels of chemicals to be introduced into the treatment process, reduction in biological treatment levels or the collection system to be shut down remotely.

Many remote systems can still be worked manually but the personnel must be available when the time comes. In the case of the St Martin, the buildings on the property have a limited fire-protection infrastructure. The main control room in the operations building, with all the electrical equipment that controls the wastewater operations, is not even protected by a halon system. There are smoke detectors, but when activated, the alarm must be called in manually to 911 dispatcher

Wastewater-treatment facilities present additional concerns to first responders. Regardless of the disinfecting agent used, there still will be hazardous materials on site. Laboratories also are likely to be on site, which should always raise a red flag. SARA Title III requires all hazardous materials to be inventoried on three separate forms. The forms, OCC-51A (small quantities), OCC-51B (small quantities in a laboratory) and OCC-51C (large quantities), must be filed with the location’s fire and police departments. These forms also list the locations of each hazardous material and how many people work in that building. Additionally, Materials Safety Data Sheets for each chemical should be kept on site for use in the event of an emergency.

As with any industrial facility, power is a concern to first responders. Wastewater-treatment facilities use electricity to collect and treat wastewater and discharge the clean effluent. There is a trend toward using alternative sources to generate this electricity. Methane gas produced during the anaerobic digester process can be used to generate part of the plant’s electricity. Methane gas adds to the list of hazardous materials and make for potential confined-space and high-angle rescues. Both scenarios present additional dangers that must be planned for during any risk analysis.

All the wastewater operations are redundant, so the entire facility can continue to operate at a reduced capacity if part of the system breaks down or is in need of maintenance. Of its five primary clarifiers, six aerations basins and six secondary clarifiers, any number can be shut down temporarily as long as one of each is running. Problems would arise if an entire component were disabled and sewage were restricted or blocked the flow of wastewater through the facility.

The clarifiers, aeration basins,, pumping stations and sewage pipes are all permit-required confined-spaces as defined by Occupational Safety and Health Administration. These areas create hazards to both employees and rescue workers. Wastewater-treatment facilities should have policies in place as guidelines for their employees to operate under when working in these areas.

First responders are not responsible for the daily operations of a wastewater-treatment facility and have little or no control over how the utility is run. They are, however, tasked with responding to emergency incidents that arise in the course of their operations. Performing a risk analysis helps understand what types of emergencies they are likely to encounter and where those are likely to be.

An incident at a wastewater-treatment facility is likely to involve multiple agencies. In addition to the fire department, personnel and resources from law enforcement agencies, environmental authorities and public health care facilities may be called on to work together. The likelihood of a successful outcome will be greater if there is communication and coordination between these entities beforehand. Information gathered from a risk analysis should be shared among those likely to be involved. Ultimately this information should lead to training drills and tabletop exercises.

Wastewater Treatment Workers

Wastewater treatment workers treat sewer and storm water to remove impurities and then release the water to rivers, oceans, or recycled irrigation and landscaping networks. Operators in waste water plants use mechanical equipment, treatment tanks, and chemicals to clean the water. This variety of processes can pose a mixture of hazards to workers.

Because there is so much water involved in the treatment process, slips, trips, and falls are the main hazard for waste water treatment workers. Practice good housekeeping by sweeping up or squeegeeing water puddles. Mark areas that are prone to puddling. Fix leaks promptly. Use flooring surfaces that provide traction. Wear shoes that have a non-slip sole.

Confined spaces are a serious concern at water treatment facilities. Exposures to a low oxygen environment or high levels of hydrogen sulfide, methane gas, or ammonia can cause serious illness or death. Survey the areas for explosion potential from flammable gas and water engulfment in times such as heavy rain and flooding. Survey the entire facility for areas with limited egress and other hazard potential. Use proper confined space procedures, personal protective equipment (PPE), and ambient air and personal monitoring to ensure your safety.

Engulfment and/or drowning in treatment tanks are hazards at treatment plants. Put guard rails around all open water sources. Keep rescue equipment such as floats and hooks available near all tanks. If you will be doing work at height over an unguarded tank, consider fall protection gear and keep a coworker nearby to monitor you. When you lift grates over waterways and tanks for access, cordon off the area and place hazard warning signs to prevent accidental falls.

Water treatment plants have pumps and valves for moving water and many moving parts such as screens, belt presses, and conveyors remove debris and move sludge. This equipment can cause caught/crush hazards if you place a hand, arm, or foot too near a moving part. Guard all moving machinery and watch for these hazards while you work. Operating this equipment in a wet environment requires maintenance and repair work, so use good work practices. Electrical safety is key when working in a wet environment, so work carefully. Also follow lockout/tagout procedures to guard against accidental equipment startup while you are working on it.

Chemicals and biological hazards abound in water treatment. Use material safety data sheets (MSDS) to understand the properties, exposure limits, PPE, and emergency actions for your treatment chemicals. Good housekeeping controls odor and pests. Practice good hygiene by wearing gloves and washing your hands frequently. Decontaminate your clothing or change before you go home from work. Speak to your doctor and consider vaccination for some of the hazards that you may encounter.

Waste water treatment can be a challenging work environment. Plants often operate continuously, so shift work and emergency work are common. Long work shifts wearing PPE can be tiring. To deal with the work load and job demands, get the rest you need and maintain your overall health. Outdoor work can expose you to cold, heat and the sun, so dress in comfortable layers and use sunscreen.


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