Sheet one
SWIMMING POOL FILTRATION LTD. 0141 641 1168
Operational procedures required for the swimming pool and medium rate filtration plant
This is the action that should be taken if your pool is SUSPECTED of a Cryptosporidium outbreak.
Proposed operational procedure for pool water sample collection for a suspected Cryptosporidium outbreak in swimming pools.
FIRST ACTION
1Close the pool to the public.
2The appropriate person appointed to collect the pool water samples for testing, (See sheet two) will be required at poolside to run pool water through a 1 micron filterover an 8 hour period at 1litre/per minute.
(A small rig including a water meter, a 60litre/hr. restrictor, a 1 micronfilter, a small sump pump andassociated pipe work and valves.)
Types of one micron filter used.
Method Basics
The protocol for this method has been described in detail by Uk's Drinking water Inspectorate and the US EPA.
The method is based on concentrating the (oo) cysts from water using specalised filters.There are two commercially available filters thathave beenapproved for Cryptosporidiumdetection, the EnvirocheckFilter from Pall and the Filta Max from Idexx.CityAnalysts canprocesssamplesthathave been concentratedusing either filter. Ifhowever it is not possilbe to filter the sample a 10 Lgrab sample canbe sent to the laboratory for analysis.
Once filtered the (oo) cysts are then eluted from the filter and isolated by immunomagnetic separation. This technique captures the(oo) cysts on antibody coated magnetic beads allowing thesample interferants to bediscarded.
The final stage in detection is staining and microscopy. The(oo) cysts are fixed onto slides and stainedtwice usingFITC labelled anitbodyto the oocyst wall protein andDAPI stain which stains the nucleic acids in the (oo)cysts.
The sample should be gathered from approximately 500mm below pool surface at a rate of 1litre per minutetwo thirds of the pool length away from the pool inlet.
3A 10litre sample should be gathered in a proper container from the backwash water on each filter.
4Samples should then be taken to the appropriate accredited laboratories for testing.
5Now is the time to do an in-depth inspection of swimming pool filtration plant daily, weekly, monthly and yearly routine monitoring reports.
6For example this should include:
1aPool chemical testing records.
2aPool test kit.Calibration certificates.
3aPool bacs testing records.
4a Pool mains water consumption (pool water meter readings)
5aFilter flocculation. (How much is used per day)
6aFilter internal inspection and reports.
7aPool chemical monitoring and dosing systems.
8aFilter pressure inlet and outlet gauges. Calibration certificates.
9aCirculation flow meter.Calibration certificates.
10aRecord of pool and poolside manual cleaning routine.
11aBalance tank cleaning and disinfecting records.
12aInformation required, Pool turnover, pool volume, water flow rate through filters. Backwash flow rates through filters,
13aWhat determents when filters should be backwashed and at what time of day is this work carried out and the records for the backwashing.Pressure gauge readings before and after backwashing.
SECOND ACTION
7If the testing proves positive, the above information will be required.
8Provided the filters contain graded filter media i.e. 16/30 etc. Slow down the filtration rate to 12.5 m³/m²/hour. The slower the water passes through the filters the more effective the filter becomes; you will collect approximately90% in the first turnover as to 10% if the flow rate is twice as fast.
9If two flocculants are added one with a negative charge and one with a positive charge we can remove particles down to about 0.5 microns the most effective way to remove the cryptosporidium oocysts.
10If you only use one floc you can increase the amount as per the recommendations.Backwash as required.
11Super chlorination should not be carried out as a normal practice, especially in indoor pools as this can create other problems in the atmosphere. The chlorine level can be increased to the normal higher level.
12The most effective way to remove bio film and the stressed oocysts is with use of stabilised chlorine dioxide in the form of T.C.D.O.
13To help eliminate dead spots in a badly designed swimming pool, the addition of several sump pumps strategically placed will help overcome dead spots. If you have a balance tank add a sump pump.
14 Water sampling for crypto should be carried as per sheet two.
15 If the pool surrounds require a deep clean now would be the time to carrie it out. The pool should be swept and vacuumed thourghly.
16 The filter internals should be inspected and purged if required.
Sheet two
Operational procedures required for the swimming pool and filtration plant
Water Testing for Cryptosporidium
The water authorities are normally called in to collect water samples; we have been present on a number of occasions when this has happened. Their experience in mains drinking water will be second to none, but in swimming pools we have a closed water circulation system with warm water, the circulating pattern in pools will differ depending on their design and the equipment used. Ninety percent of the pollutants are in the top six inches of the pool water, the normal design nowadays is level deck pools where ninety percent of the pool water enters a balance tank.
Water samples should be collected by an experienced swimming pool filtration engineer,Someone that can differentiate between water flow patterns, dead spots and who understands/knows swimming pool filtration systems.
When the pool is closed to the public the following can commence.
The Plantroom
1Collect 5 litres of water from the strainer box on the circulating system that is in use. Collect 1kilo of filter media within 100mm of the surface from each filter. (If the filters are fitted hydraulically correct, then from the first filter.)
2Collect 10 litres of pool water from the backwash pipe one minute after the backwash water starts going down the drain, if filter system hydraulics are incorrect take the sample from the filter that is collecting the most dirt. If the backwash pipe is on a closed system take the sample from the bulk air line.
3Collect another 10 litres from the rinse valve system before the water returns to the pool. If the filter does not have a rinse valve take the 10 litre sample from the filter drain valve.
Pool Side
4A system that is capable of circulating at 60 litres per hour and passing the water through a one micron filter should be used at poolside. A water meter should be fitted so an accurate measurement of the amount of water passing through the one micron filter can be determined.
5The above system water suction pipe should be placed two thirds of the way along the length of a standard shallow end water inlet and a deep end water outlet pool, 500mm below water level. Other pools with water inlet and outlet designs the sampling should be left to the discretion of the swimming pool filtration engineer. The water sample system should run for a minimum of 8 hours i.e. 480 litres
6Using the same type of equipment as above but with the one micron filter removed, 10 litres of sample water should be collected from any dead spots in the pool circulation. Or use sump pumps to eliminate the dead spots.
7Using the same type of equipment as above with the one micron filter the balance tank water should be sampled over a period of 8 hours i.e. 480 litres. A sump pump should be used to agitate the water. (If the balance tank is not hydraulically correct then this will be the pools worst dead spot.)
8Filters with pea gravel below the laterals, infilling the dished end of the filter will require specialised treatment.