guidance notes_swimming pools bs

8/14/2019 Guidance Notes_Swimming Pools BS

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GUIDANCE NOTES

Swimming Pools - Building Services

CONTENTS1 Introduction

2 Design

3 Pool Water Quality

4 Filtration

S Water Circulation and Distribution

6 The Internal Environment

7 EleCtrical Services

SPlumbtng and Drainage

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10 The Plant Room

11 Management and Operation

12 References

One of a seriespropared to give clear, concise, comprehensive and up-to-date information onthe planning, design and management of sports buildings. They are ntended to promote valueformoney alliedwith quality n all new and refurbished sports and recreational acilities.o Sports Coufld: nber 994 (

This documentI contains j pages


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SWIMMING POOLS - BUILDING SERVICES

1. Introduction 2. Design

Good building services are essential for high quality indoorswimming pools. Building services account for 35-50% of

the total cost of most modern pools - from the most basicpools serving a small local community o major leisurepools with many separate water areas and features.

A safe, comfortable and attractive internal environment isessential in order o attract and sustain high levels of use.The challenge is substantial: a large internal volumecontaining thousands of gallons of warm water which isconstantly being agitated and requires continual chemicaltreatment to deal with pollution from large numbers ofbathers demands high levels of environmental service tomaintain satifactory conditions. This means that theseelements need to be taken into account at the earliestpossible stage of he design.The design, location, plant space and distribution of thevarious building services elements should be important actorsin the general design and planning of he facility. Due to therelative complexity of the installations it is also critical thatoperation, maintenance and energy are also given earlyconsideration when the management and operationalplanning for the facility is done. Achieving the buildingservices hat meet the requirements of a particular facilityandoperational strategy willnecessarily nvolve some compromises,and udgments based on priorities and assessment of criticalfactors. This guidance note addresses hose ssues.

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Swimming pools make serious demands in terms of thedesign, construction, operation and maintenance of thebuilding services. Design comes first, and is critical to asuccessful facility

The starting point for the design of any acility should be acomprehensive assessment by the client body of the scaleof pool wanted, taking into account existing provision,projected use, future plans, etc. This information can thenbe used to estimate the bathing load and pattern of use,which in turn establishes he requirements that theenvironmental service systems in general, and the poolwater reatment system n particular, willneed to satisfy.

Design BriefAdesign brief should be produced by he client body thatis responsible or the proposed pool. It should provide abroad description of requirements and set out the principalparameters of the design. It is important that the designbrief highlights the main factors that will govern thedetailed design of the various building services elements,including the pool water reatment. These should include:

the size and type ofpool(s) and water eatures to beincluded;

the anticipated bathing load and patterns ofuse;

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Figure 1: Typical Large Pool Mechanical Services Schematic

Fresh

Reaction Sandvessel filter

Ozone injection

)vessel

Ozone gasgenerator


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the desired pool water quality parameters includingtemperatures);

details ofany specific equirements or chemicaltreatment, filtration, circulation, dilution, ventilation, etc;

environmental quality parameters or all areas; proposed main plant areas and ocations, etc; details of mains supplies and connections of fuel,

electricity, drainage, etc;

the nature of he ncoming water supply - hard or soft,for example;

plant operation and maintenance; energy.

Pool Water Pollution

Pool water s being polluted to some extent, primarily bybathers, the whole time it is being used. Whatever thesource and type of pollution, it should be minimised atsource, and dealt with by appropriate water treatmentwhich should ensure that pool water s clear and presentsno special risk of nfection.

The substances which can be introduced o pool waterfrom bathers' bodies fall into three categories:

tissues and excretions urine, sweat, mucus, saliva, hair,skin scales and faecal matter;

dirt -many types, organic and inorganic; cosmetics powders, creams, lotions, oils, etc.

3. Pool Water Quality

The most critical element in providing a good swimmingpool environment is pool water quality. This is affected bypollution (including bacteria and viruses), the byproducts ofdisinfection, and mineral salts - both naturally present andadded as part of he water reatment regime.Much of he information in this section is derived from thePool Water Guide (see Reference section, page 9), which isthe standard text on the subject.

Figure 2: Typical Small Pool - Mechanical Services Diagram

Fresh airsuppiy

Of hese, the biggest problem is generally the urea in urineand sweat. This reacts with disinfectant in the pool waterto produce combined chlorine (or bromine) - the maincause of eye and skin irritation and irritant fumes in the airabove he pool.

Many bacteria and viruses (collectively, micro-organisms)are introduced into the pool by bathers. The majority areharmless; even those that can cause disease (calledpathogens) present no significant risk in a properlydisinfected and managed pool. As an important check,though, microbiological testing of the pool water shouldbe done egularly.

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Monitoring sensor

*Some radiators hav e thermostatic vaives,AUcons have thermostatic valves with remote sensors


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Chlorinated isocyanurates hese granules or tablets arean alternative means of providing chlorine-baseddisinfection Cyanuric acid is present in the pool wateralongside he residual chlorine. It s recommended that thelevels should t,e: free chlorine residual 2.5 to 5.0mg perlitre; cyanuric acid less than 200mg per litre (ideally 50 to100mg per litre)

Bromine There are number of disinfectant systems whichutilise bromine as he main disinfectant agent.

Liquid bromine disinfects in a similar way to chlorine. It isrecommended that the total bromine residual should bemaintained between 1.5 and 3.5mg per litre (ideallybetween 2.0 and 2.5mg per litre). The combined bromineresidual should be no more than half he free bromine.

A solid bromine donor- bromochlorodimethylhydantoin(BCDMH) - is available in tablet form. There has been

considerable debate over the years about reports of skinirritation and rashes associated with this, so designers andoperators should be vigilant, ensure that the recommendedguidelines are adhered to, and provide adequate dilutionwith fresh water. The recommended level of total activebromine residual with this system is between 4 and 6mg perlitre; dimethylhydantoin hould not exceed 200mg per itre.

Another system nvolves sodium bromide and hypochlorite.The recommended bromine residual levels are as for liquidbromine; a bromide reserve should be maintained between9 and 1 5mg per itre.

Ozone This system s different n that it purifies the wateras it passes through he plant room, but does not provide achemical residual in the pool water tself. So conventionaltreatment (usually with hypochlorite) s applied as well - but

this can usually be controlled at a lower evel than chlorinealone. Ozonation is comparatively expensive, but can deliverhigh quality pool water.

pH Value

The degree of acidity or alkalinity (basicity) of water ismeasured in terms of its pH value. A pH value of 7 isneutral; values below 7 indicate increasing acidity, valueshigher than 7 increasing alkalinity. Disinfectant activity is

significantly affected by pH. All chlorine disinfectants,ozone + chlorine, and BCDMH work best towards thebottom of he recommended range of pH 7.2-7.8. Brominedisinfectants operate best in the pH range 7.8 to 8.2

The control of pH is generally by the addition of acid oralkali, depending on the type of disinfectant and thesource water. Alkaline disinfectants (sodium and calcium

hypochlorite) normally require an acid (generally sodium

bisulphate, carbon dioxide or hydrochloric acid) to controlpH. Acidic disinfectants (chlorine gas, liquid bromine,chlorinated isocyanurates) normally require the addition ofan alkali (usually sodium carbonate).

Some combinations of source water and disinfectant willresult in a pool water not requiring any pH adjustment; it salways good practice to choose a disinfectant with thesource water in mind, and to adjust pH only enough tobring it within the recommended ange. Any furtheraddition of chemicals to control pH will be of no benefitand may be detrimental to water quality.

Balanced WaterA balanced water is technically one that is neither scaleforming nor corrosive. For the majority of pools, however,

Figure 4: Typical Ozone Pool Water Treatment


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the water will generally be adequately balanced f he pH ismaintained within the recommended range. The othermain factors affecting water balance are alkalinity,hardness and dissolved solids.

Alkalinity The total alkalinity ofpooi water s a measure ofthe alkaline salts dissolved in it. The higher the alkalinity,the more resistant water is to changes in its pH value -generally a good thing. The recommended range is 75 to250mg per litre.

Hardness The total hardnes of pooi water s a measure ofits calcium and magnesium salts. Calcium hardness isparticularly relevant to swimming pools: if it s below about40mg per Iitre,the water may be corrosive. Therecommended minimum value is 75mg per litre; althoughthere is no theoretical upper limit, values over 500mg perlitre are unlikely to be ofany benefit.

Total dissolved solids (TDS) This is the sum weight of allsoluble material in the water and its measurement s usefulas a warning of potential overloading or lack of dilution ina swimming pool. It should therefore be monitored andmaintained at a maximum of 1000mg per litre above thatof he source water with an absolute maximum of 3000mgper litre. In general TDS can only be controlled by dilution,usually via filter backwashing but the fewer chemicals thatcan be used, he better.

Sulphate As high levels of sulphate can attack cementand grout, its concentration should be separatelymonitored and 360mg per itre should not be exceeded. If

sulphate levels cannot be maintained below this,sulphate-resistant Portland cement and epoxy grout mayhave to be used.

4. Filtration

Maintaining the clarity of pool water s critical for safetyand comfort. Clarity is reduced by turbidity (colloidal orparticulate matter in suspension in the water). It isimportant to determine the source ofany turbidity- n caseit can be dealt with directly - but the remedy s likely to beadequate iltration.

Sand filters - rather than the cheaper cartridge and pre-coat or diatomaceous earth filters - are recommended forall non-domestic swimming pools. Because filter efficiencyfalls off rapidly at velocities of over 30m/h, medium ratefilters (1 1-30m/h) are recommended. High-rate filters (31-5Dm/h) cannot handle colloids effectively; low-rate filters(up to lOmIh) tend to harbour bacteria.

Regular, effective backwashing cleaning ilters by reversingthe flow of water hrough the filter bed and dischargingthe water to waste) is essential iffilters are to operateefficiently. It should be carried out strictly n accordancewith manufacturers' nstructions, at least once a week.

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It is recommended that a minimum of two filters areprovided wherever possible, to increase flexibilityand toprovide some standby capacity during maintenance.

Filters in public poois are generally of the vertical,downward-flow ype, but both horizontal and dual-flow(downward and upward flow) types have been usedsuccessfully. Mild steel with a corrosion protection lining isthe most common material for filter tanks, but stainlesssteel, glass fibre and concrete have all been usedsuccessfully.

The addition of coagulants assists the removal of dissolvedand colloidal material by producing a flocculate which ismore easily rapped on a filter. Aluminium sulphate (alum),polyaluminium chloride (PAC), sodium aluminate, ironchlorides and iron sulphates have all been successfully sedas coagulants n swimming pools.

5. Water Circulation andD St r but on

Water circulation and distribution are critically important inpool water quality.

Turnover PeriodThe time taken for an amount equivalent to the totalvolume of pool water to circulate through the pooi andtreatment plant is known as the turnover period. Thechoice of turnover period for a pool (or part of any pool)should be one of the earliest design decisions once thepool type, size, shape and bathing load are agreed. Theshorter the turnover period, the more frequently andthoroughly the water s being reated.

Recommended maximum turnover periods for various pooltypes and areas are: diving poois 4-6 hours competition pools (25-50m long) 3-4.5 hours

conventional pools (up to 25m long) 2.5-3 hours leisure poois up to 0.5m deep, 0.5 hours;0.5-1 m deep, 0.5-1 hour;1-1.5m deep, 1-1.5 hours;

over 1 .5m deep, 2-2.5 hours.

Circulation

It is very important that treated water s distributed to allparts of the pooi and that polluted water is removedeffectively, especially from areas most densely populated bybathers. Pool circulation systems which allow substantialproportions of water to be taken from the surface can beparticularly efficient, as the pollution is generally greatest atthe water surface.


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There are hree main systems for removing surface water -level-deck, overflow or scum channels, and skimmers. Themost efficient of these is level-deck (able to handle up to100% of the circulation flow via surface removal) and theleast efficient skimmers (typically handling 5-10% of total

flow via the surface). In order to ensure that the waterremains at the correct level at all times, a balance tank,together with an automatic make-up water supply tank, isusually required.

Pool water inlets should be arranged to ensure that eachtakes its required proportion of flow and that inletvelocities do not exceed 1 .5 to 2m/s. Outlets must bearranged so that there is no risk of bathers being drawntowards them or trapped.Sufficient pumping capacity must be provided to ensurethat the required pool turnover period is achieved when

filters are dirty and providing maximum resistance.Sufficient standby pumping capacity should be provided toallow full circulation to continue when one of the mainpumps is not running. The pumping system should becapable of reduced flow rates when the pool isunoccupied, and must be able to provide the required lowrate for backwashing.

6. The Internal Environment

Trends towards higher water temperatures can be linkedto a number of problems including higher energy costs,increased water and air pollution, discomfort for staff,deterioration of the building abric, etc and this has ledto the following recommendations for maximum poolwater emperatures.27C (80.5F) competitive swimming and diving, fitness

swimming, training

28C (82.5F) recreational, adult teaching, conventionalmain pools

29C (84F) children's teaching, leisure pools

30C (86F) babies, young children, disabled.

Ventilation and AirCirculation

The pool hall ventilation system is normally the primary (oronly) means of removing contaminants rom the poolatmosphere and controlling the pool hall air quality,temperature and humidity. It is generally recommendedthat air is well distributed over the whole area of the poolhall and that air movement within the occupied zone ismaintained within acceptable limits for bather comfort.Extracting air at low level adjacent to sources ofcontamination and evaporation may be beneficial.

The ideal ventilation rate for a pool, taking into accountvarying external conditions, bather loads, evaporation,water quality, etc is very difficultto estimate and will, by

Maintaining a satisfactory environment in the pool hall,and all the other areas of the building, is essential for thecomfort of users. It also ensures a reasonably extendedworking life for the pool building. Heating and ventilationneed to take nto account a wide range of actors such asbathing oad, water emperature and quality, materials andinsulation of the pool hall envelope, plant location,integration with the building structure, and capital,operating and ife-cycle costs.

Temperature and HumidityThe air temperature of he pool hall needs to be maintainedat a comfortable level -primarily for bathers, although staff,instructors, lifeguards and spectators also needconsideration. Pool water emperature and air temperatureand humidity need to be controlled so that user comfort ismaximised and evaporation from the pool surfaceminimised. Typically this balance s best achieved with poolair temperature at or up to 1 degree C above pool watertemperature, and a relative humidity of 50-70%. Airtemperatures should not, n general, exceed 30C.

The ideal water emperature will obviously depend on the

activity, but it s not practicable o vary water emperaturesto suit every change in use of a particular pool area. So it sessential that optimum water temperatures are selectedand controlled for each pool.

Figure 5: Typical AirDistribution

B. Low-level extract

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A. High-level extract


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9. Energy ManagementSwimming pools are an almost unique building type: theyoperate at high temperatures and humidities throughout theyear. This creates potentially very high heating loads, so poolbuildings should be very well insulated (ideally, at least 50%better than current general building regulations) and wellsealed from both the outside and any surrounding areas.

Heating the ventilation air will generally be a substantialheat load due to the relatively high ventilation volumesinvolved, so simple heat exchange devices (for exampleplate heat exchangers or round-around coils) should beprovided whenever possible to maximise energy reclaimfrom exhaust air.

There are many energy efficiency devices and techniqueswhich can be applied to pool nstallations - thermal wheels,heat pumps, desiccant heat recovery, combined heat andpower units - together with various other heat recoverymeasures. It is important that these are carefully andseparately evaluated over the projected life cycle of thebuilding services installation - taking into account factorssuch as the management and maintenance implications -before selection of he most appropriate for any facility.It will normally be necessary o run the pool ventilationsystem for at least part of the time that the pool is notactually in use, in order to prevent condensation. The useof an effective pool cover can normally reduce thisrequirement and therefore substantially reduce energy use.The Department of the Environment's Building ResearchEnergy Conservation Unit BRECSU) are currently producinga series of publications providing advice on energyefficiency n swimming pools.

10. The Plant Room

It is essential that adequate space and access is providedfor all building services plant and equipment, to alloweffective operation and maintenance. As a guide, 25%of the water area is required for pool water treatment,plant and 15% of the total building area for heating,ventilation and electrical plant and equipment.

Water treatment plant should ideally be located as close aspracticable to the pool; sufficient external access should beprovided for possible replacement and refurbishment ofmajor plant. There must be enough safe, convenientstorage of chemicals with separate, contained storageareas for different ypes of chemical where necessary andadequate external access for delivery, etc. Some items ofplant may need to be located in clean, dry areas withspecific environmental conditions (for example electricaldistribution boards, control panels, ozone generators etc).

11. Management andOperation

The detailed management structure will depend on thesize, type and nature of the pool. But whatever the scaleof the operation, management and staff must have anunderstanding of the pool water treatment system andassociated environmental services installations. Whateverspecialist staff are employed, the ultimate responsibility orthe operation of the building is carried by themanagement team. So all management staff must be ableto monitor the operation of the building and, wherenecessary, take action to restore conditions in accordancewith the appropriate guidelines.

The manager or pool operator is responsible under the

Health and Safety at Work Act 1974 to ensure, as far as isreasonably practicable, the health and safety of employeesand others who may be affected by the undertaking. Thiswill include protecting the public who use a swimmingpool. The Health and Safety Executive/Sports Councilpublication, Safety in Swimming Pools gives detailedguidance n this area.

12. References

POOL WATER TREATMENT ADVISORY GROUP POOLWATER GUIDE The treatment and quality of swimmingpool water

HEALTH &SAFETY EXECUTIVE/ SPORTS COUNCIL Safety inswimming pools

Chartered Institution of Building Services Engineers (CIBSE)Lighting guide LG4 - sportsSports Council Guidance Notes

Swimming pools - changing and elated amenities in publicindoor swimming pools

Swimming pools - improvements and alterationsto existing small poolsSwimming pools - small public ndoor

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Sports Council Guidance Notes DisclaimerThis guidance note is one of a series produced by theSports Council. It is intended to provide helpful dataguidance which the reader can file for permanentreference.

Applicants for Lottery funding are advised, however, thatthese guidance notes and the guidelines contained hereinhave been prepared as a basic guide only. Applicants, theirrepresentatives or advisers, should not view the guidelinesas a substitute for obtaining comprehensive expert or

professional advice in relation to their applications orLottery unding.

These guidelines and the Sports Council policies on lotteryfunding applications are subject to change from time to

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time, including variations required to comply withGovernmental directions on the application of lotteryfunds. The Sports Council reserves the right to amend,supplement and/or discontinue at its absolute discretion,for whatever reason, any or all of the guidelines set out nthis publication.

While every effort has been made to ensure the accuracy ofthe guidelines and other nformation contained within thispublication, the Sports Council, its servants or agents shallnot at any time, in any circumstances, be held responsibleor liable to any applicant or any other party in respect ofany loss, damage or costs of any nature arising directly orindirectly from reliance placed on the guidelines within thispublication or any other guidelines or policies issued by heSports Council.

A ull ist of guidance notes and other sports council publications is available 3.00 ISBN: 1 872158 gg 4from the nformation centre:The Sports council16 Upper Woburn PlaceLondon WC1H OQPTel: 0171-388 1277 Fax: 0171-383 5740 Sc/387/3.SM/2/95

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