Here is a SCENARIO 
"
Water Wise Analytics (WWA) is a successful and growing organisation carrying out water quality testing and analysis. WWA is based at a purpose-built facility within an industrial unit, on the edge of a large town with good access to main roads. There are 30 workers at WWA, mainly consisting of scientists and technicians working in four different labs. In addition, the organisation has a fieldwork team. Most days the fieldwork team are out at various sites. Their role is to inspect water sources and take water samples from numerous locations, bringing these back to the labs for testing. WWA also has a range of office-based support services, including an administration team, IT support, human resources, and a health and safety team. There are 4 purpose-built labs, each specialising in different types of testing and analysis. Lab 1 identifies contaminants in water samples, and where required produces a water treatment plan. This will be done when the water source needs to be treated so that it is fit for purpose. Lab 4 is a microbiology lab specialising in testing for Escherichia coli (E. coli 0157). Each lab has a range of equipment relevant to the type of work carried out, including workbenches with stools, chemical storage cupboards under the workbenches, fume cupboards, autoclaves, incubators, and microscopes. Each lab also has its own changing rooms and toilets. The scientists and technicians are highly trained in their specific work. All scientists and technicians receive detailed health and safety induction training about their own safe laboratory working procedures. 

Laboratory 1 (Lab 1) 

In this lab, workers are testing water samples and working on water treatment plans. The treatment plans often require sodium hypochlorite to be added to water systems at an appropriate dose, and the lab workers carry out tests to determine the dosing regime required. These tests involve adding measured amounts of sodium hypochlorite to water samples. The sodium hypochlorite is supplied in 5 litre containers that are a manageable size to handle in the lab, and allow relatively small amounts of sodium hypochlorite (typically 100 - 200mls) to be dispensed safely into measuring cylinders. Today, worker B finds that the 5 litre container that is kept in the lab’s cupboard is empty, and visits the stores to collect another. At the stores, worker B is informed that sodium hypochlorite is now being purchased in a 20 litre container which is better value for money. The stores’ manager shows worker B the advert in the supplier’s catalogue (see supporting document 1), and seems pleased that they have managed to save the organisation money. They tell worker B that, in future, the 20 litre container will be delivered straight to the lab, so fewer trips to the stores will be needed. Worker B, who is now running late on the day’s work schedule, returns to Lab 1 with this much larger container. They feel quite hot after carrying the 20 litre container, so push up the sleeves on their lab coat before putting on their PPE. Remembering their induction training worker B does not want to decant any of the sodium hypochlorite into an unlabelled container, as this is not good practice. Instead, they lift up the container and start to pour the required amount directly into the measuring cylinder on the workbench. Unfortunately, the sodium hypochlorite comes out of the container very quickly, spilling down the side of the measuring cylinder and onto the workbench. Worker B tries to stop the measuring cylinder from falling over, and in doing this partly loses their grip on the large container of sodium hypochlorite. There is now sodium hypochlorite all over the workbench, the equipment, and on the forearms of worker B. Their colleagues grab the spill kit and rush to assist worker B, and deal with the spillage. The next day when Lab 1’s manager returns from annual leave, they see the accident report on their desk. They are concerned that there will be lots of questions raised about the safe working methods in Lab 1. They quickly look at the existing hazardous substance risk assessment for this task, and the safety data sheet (SDS) for sodium hypochlorite (see supporting document 2). The lab manager is thankful that the company-wide control system is now in place for hazardous substances. This also means that they can confirm that all workers at WWA received training in the safe handling of chemical and biological agents earlier in the year. However, that makes it more surprising to the manager that this accident happened.

Fieldwork Team
The Fieldwork Team meet up in their office to allocate the work for the day. The fieldwork manager (FWM) has a list of samples that need taking or collecting, and sites where inspections are required. There are three members of the Team who have been in the role for several years. Due to an increased workload, three new workers have been recruited to the Fieldwork Team; they have just finished their training and are about to start going out to sites on their own. Fieldworker A is one of these new recruits; they came to this job straight from university, and are very eager to go out to sites on their own in their company car. Work is allocated to the experienced fieldworkers and the two other newly-trained fieldworkers. The only work that is left to do during the day involves taking samples from various natural springs and boreholes. Most of these sampling points are located down tracks, away from main roads in isolated rural locations and on farmland. The FWM is concerned that this work is too much for new fieldworker A’s first job on their own. Fieldworker A is very keen and states that they are aware of where the sampling points are. They are familiar with these sites, having been out with one of the experienced workers, and because they go cross-country running in these areas several times a week. The FWM is convinced by fieldworker A, but insists that fieldworker A must phone them at 14:00 to update the FWM on their progress. Happy with this, fieldworker A takes the details of the sample collections needed on their mobile phone and gathers what they need, including safety equipment, before leaving for the first sampling point. 

Fieldwork manager 

The FWM is pleased that fieldworker A can take the samples today, as the FWM needs to speak to the contractors, Find & Dig (F&D), about a large job starting next week. F&D are contracted by WWA when an excavation is needed in order to locate, inspect, and sample water sources. The job next week is at Marshes Road, and once excavated, the FWM will go out to inspect and take samples along with a colleague. In the meantime, the FWM needs to email F&D’s manager to check that all the arrangements are in place (see supporting document 4). 

Fieldworker A

 Meanwhile, fieldworker A arrives and parks as close as possible to the first site where they need to take a sample. They have started with the site furthest away from the facility, and intend to work their way through the jobs back towards Lab 1, delivering all the samples when they have finished. At this first site they will have to walk about 1km to the sampling point. Fieldworker A starts walking down a rough track. After a few minutes’ walk the path has ended and fieldworker A is walking across a rocky terrain covered in slippery moss and grass. The sampling point is further up the hill in front of them, in a small, wooded area. As they keep walking it starts to rain. Fieldworker A is used to rain from their cross-country running, so carries on walking. After a few minutes, fieldworker A arrives in the wooded area and starts looking for the natural spring. After some time, fieldworker A still cannot find the sampling point. They get their phone out to check the location again from the job details. They notice that it is now 14:30, but they do not have a phone signal. Eventually, they find the natural spring and take a sample. As they come out of the wooded area it is raining even harder and it is very dark. As they clamber over the rocky terrain they slip, falling to their knees. Fortunately, they only bruise their knees. When fieldworker A gets back to the car, they check their phone; they have a very weak phone signal, but they have several missed calls from the FWM. 

Find & Dig (F&D) 

A week later, November 6 is a very cold morning when F&Ds’ workers arrive at the site on Marshes Road. Worker X is going to begin with operating the hand-held percussive breaker (breaker), so they put on the required PPE including hearing protection and eye protection, as well as steel toe-capped boots. Meanwhile, worker Y is unloading the breaker and setting it up ready for worker X. Workers X and Y are concerned that worker Z will be absent this morning, as worker Z is the most experienced member of the team, having spent many years working for several organisations that do this type of work. Workers X and Y feel under pressure as they know that workers from WWA will be coming to the site soon. Workers X and Y will share the use of the breaker equally to remove as much of the road material as possible. After this, they will change to hand digging as they get close to the water pipe. Around 11:15 the WFM from WWA arrives on site, and has to wait for the digging to be completed before they can inspect the water pipe and take samples back to the lab for testing. 

Important contract for Laboratory 4 (Lab 4) 

Eighteen months ago, WWA won a major contract to carry out bathing water quality testing, on behalf of the national environmental regulator. Water samples from inland and coastal bathing locations are regularly collected and analysed in Lab 4 (the microbiology lab) at WWA. The analysis is done to determine the level of any harmful biological agents, in particular E. coli 0157. The results produced by WWA are published on a public information website for anyone to access. This is a high-profile project; there has recently been a lot of public attention due to health problems experienced by people swimming in a small number of these bathing waters. There are currently many posts on social media from swimmers who have become unwell after swimming at Green Valley Lake. The shareholders at WWA are increasingly concerned that the organisation’s involvement in this work is attracting bad publicity for WWA, and this is on the agenda of the forthcoming shareholders’ meeting. As part of this contract, Lab 4 receives a constant stream of weekly samples from each of the 300 bathing water locations. The lab workers are very aware of the need for hand hygiene and wear gloves to handle each 100ml bathing water sample. Each sample is passed through a specific membrane filter that traps the E. coli 0157. The filter is then placed on a Petri dish that contains a special growing medium (agar). After incubation at 36°C for approximately 24 hours, the E. coli 0157 is visible as blue or violet colonies on the agar. The number of colony forming units (cfu’s) per 100mls of water sample are counted. These results are reported on the public information website. Lab 4’s workers are very experienced, and although the pace of work is intense, they take great care and pride in their work, and so minimise the opportunity for contamination from water samples. 

Using microscopes

In order to count the number of cfu’s on the Petri dishes a microscope is needed. Workers in Lab 4 spend a significant proportion of their time carrying out work using a microscope. The microscopes owned by WWA are very basic, quite heavy, and are not adjustable. Typically, a worker will spend eight hours a day looking at the samples through the microscope, counting the number of colonies that have grown."

Here is a question "Posts on social media from swimmers who swam at Green Valley Lake in 
the first two weeks of June, report that many have since been ill. The 
swimmers are reporting stomach pain, but others are more unwell.
(i) Explain how these swimmers at Green Valley Lake have become ill. (15)
Note: Your answer must be based on the information in 
supporting document 3."

Below is the best information, I can provide to you for what is  in the document 3.

"
Document 3 is a supporting document for an assessment on bathing water catchment area data. There is a table showing data for two bathing water locations, Green Valley Lake and White Cliff Cove. The table includes the description of water catchment area for the bathing water location,  the size of the catchment area, the average monthly rainfall in June (based on last 20 years), the actual rainfall in June and the average temperature in June.

The data in the same table shows that Green Valley Lake is an inland waterway. . The lake is surrounded by hills. These hills are mainly used for grazing livestock. It has a catchment area of 840 m2 and an average monthly rainfall in June of 62 mm. The actual rainfall in June in week 1 was 98 mm, week 2 was 78 mm, week 3 was 57 mm and week 4 was 71 mm, and the average temperature in June was 18°C. 

White Cliff Cove is a coastal waterway. The cove is formed within coastal chalk cliffs. The majority of the land in the catchment area is farmland used for growing crops. It has a catchment area of 450 m2 and an average monthly rainfall in June of 45 mm. The actual rainfall in June was 52 mm in week 2, 36 in week 2, 48 in week 3, and 61 in week 4 and the average temperature in June was 19°C. 

The national bathing water standards for E. coli 0157 are:

Excellent: <500 E.coli (cfu/100 ml)* 
Good: <1000 E.coli (cfu/100 ml)* 
Poor: >=1000 E.coli (cfu/100 ml) * 
(*colony forming units/ 100 mls water)

Document 3 further shows two bar chart bathing water sampling results for a six-week period from mid-May to the end of June for Green Valley Lake and White Cliff Cove. The x-axis of the chart represents the week number (6 weeks in total) starting from 3rd week of may and ending with 4th week of june , while the y-axis shows the E.coli count per 100ml starting from 0 and going all the way to 4000. Each bar in the chart corresponds to the E.coli count for a specific week. Here is the detail from the bar chart. 

In the third week of May, the concentration of E. coli 0157 was 900 cfu/100ml in Green Valley Lake and 100 cfu/100ml in White Cliff Cove.
In the fourth week of May, the concentration of E. coli 0157 was 900 cfu/100ml in Green Valley Lake and 100 cfu/100ml in White Cliff Cove.
In the first week of June, the concentration of E. coli 0157 was 2000 cfu/100ml in Green Valley Lake and 320 cfu/100ml in White Cliff Cove.
In the second week of June, the concentration of E. coli 0157 was 4000 cfu/100ml in Green Valley Lake and 180 cfu/100ml in White Cliff Cove.
In the third week of June, the concentration of E. coli 0157 was 3550 cfu/100ml in Green Valley Lake and 220 cfu/100ml White Cliff Cove.
In the forth week of June, the concentration of E. coli 0157 was 3000cfu/100ml in Green Valley Lake and 200 cfu/100ml White Cliff Cove."